CN209927073U

CN209927073U - Cavity length measuring device of dielectric cavity

Info

Publication number: CN209927073U
Application number: CN201920335972.4U
Authority: CN
Inventors: 陈昌林; 吕欣怀
Original assignee: Jiangsu Hongkai Sensing Technology Co Ltd
Current assignee: Jiangsu Hongkai Sensing Technology Co Ltd
Priority date: 2019-03-15
Filing date: 2019-03-15
Publication date: 2020-01-10
Anticipated expiration: 2029-03-15

Abstract

The application discloses chamber length measuring device in dielectric medium chamber, chamber length measuring device in dielectric medium chamber includes: a sensor, a demodulation device; the sensor comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity, a first reflection point, a second reflection point, a conductor reflection surface and a dielectric cavity; the conductor reflecting surface can move or deform to cause the cavity length of the dielectric cavity to change; the distance between the first reflection point and the second reflection point is influenced by the change of the distance between the second reflection point and the conductor reflection surface; when the distance between the first reflection point and the second reflection point is unchanged and the distance between the second reflection point and the conductor reflection surface is changed, the resonant frequency of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the distance between the second reflection point and the conductor reflection surface is determined based on the change amount of the resonant frequency.

Description

Cavity length measuring device of dielectric cavity

Technical Field

The application relates to a measuring technology, in particular to a cavity length measuring device for measuring a dielectric cavity based on a microwave principle.

Background

The measurement technology has various types such as pressure measurement, displacement measurement, strain measurement, tilt angle measurement, force measurement, and the like depending on a measurement object, and a high-precision measurement result is a target pursued by the measurement technology, and for this purpose, an open type hollow coaxial cable-fabry perot resonator sensor based on an open type hollow coaxial cable-fabry perot resonator is proposed.

The open type hollow coaxial cable-Fabry-Perot resonant cavity sensor measures the cavity length variation of the hollow coaxial cable-Fabry-Perot resonant cavity by using two strong reflection points, and can realize wide-range high-precision measurement. However, the demodulation accuracy and the resolution of the cavity length of the hollow coaxial cable-fabry-perot resonant cavity sensor need to be improved, so that the sensor is not suitable for measuring pressure intensity and the like based on strain or diaphragm deflection measurement. In addition, the hollow coaxial cable-fabry-perot resonator sensor adopts a contact structure, so that certain sliding friction force or rolling friction force can be generated, and a great error can be caused on the sensor with extremely high sensitivity requirement.

Disclosure of Invention

In order to solve the above technical problem, an embodiment of the present application provides a cavity length measuring device for a dielectric cavity, which may be a contact structure or a non-contact structure, and can implement high-precision measurement of the cavity length of the dielectric cavity.

The cavity length measuring device of dielectric cavity that this application embodiment provided includes: a sensor, a demodulation device; wherein,

the sensor comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity, a first reflection point, a second reflection point, a conductor reflection surface and a dielectric cavity; the first reflection point is arranged at a first position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the second reflection point is arranged at a second position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the conductor reflection surface is arranged at a third position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, relative movement does not occur between the first reflection point and the second reflection point, and the reflectivity of the first reflection point and the reflectivity of the second reflection point are larger than or equal to a preset threshold value; a dielectric cavity is arranged between the second reflecting point and the conductor reflecting surface, and the dielectric in the dielectric cavity is a conductor or an insulator and is solid, liquid or gas; the conductor reflecting surface can move or deform to cause the cavity length of the dielectric cavity to change; the refractive index of the intra-cavity medium of the dielectric cavity may change, resulting in a change of the cavity length of the dielectric cavity;

the demodulation device is connected with the sensor, and comprises a demodulation main board and a coaxial cable and is used for analyzing microwave signals in the open type hollow coaxial cable-Fabry-Perot resonant cavity to obtain the resonant frequency/resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, wherein the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is the distance between the first reflection point and the second reflection point, and the distance is influenced by the change of the distance between the second reflection point and the conductor reflection surface; when the distance between the first reflection point and the second reflection point is unchanged and the distance between the second reflection point and the conductor reflection surface is changed, the resonant frequency of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, the distance between the second reflection point and the conductor reflection surface is determined based on the change amount of the resonant frequency, and the distance between the second reflection point and the conductor reflection surface is the cavity length of the dielectric cavity.

In an embodiment of the present application, the sensor further includes a housing, or a housing plus an inner rod, where the housing is an outer conductor of the sensor, and the inner rod is an inner conductor of the sensor; wherein,

one end of the open type hollow coaxial cable-Fabry-Perot resonant cavity is connected to a radio frequency coaxial cable adapter, and the radio frequency coaxial cable adapter is connected to the demodulation main board through a coaxial cable; or one end of the open type hollow coaxial cable-Fabry-Perot resonant cavity is directly connected to the demodulation main board;

the other end of the open type hollow coaxial cable-Fabry-Perot resonant cavity is connected with the end surface of the outer shell and the conductor reflecting surface by conductors, the end surface of the inner rod is connected with the conductor reflecting surface by an insulator or a conductor with the resistivity more than or equal to a preset threshold value, and under the condition, the second reflecting point is the end surface of the inner rod conductor region; or the end surface of the inner rod is connected with the conductor reflecting surface by a conductor, the end surface of the shell is connected with the conductor reflecting surface by an insulator or a conductor with the resistivity more than or equal to a preset threshold value, and in this case, the second reflecting point is the end surface of the conductor area of the shell; or the end surfaces of the outer shell and the inner rod and the conductor reflecting surface are connected by an insulator or a conductor with the resistivity more than or equal to a preset threshold value, and the end surfaces of the outer shell and the inner rod are on the same section, in this case, the second reflecting point is the end surfaces of the outer shell and the inner rod; or the end surfaces of the outer shell and the inner rod and the conductor reflecting surface are connected by an insulator or a conductor with the resistivity more than or equal to a preset threshold value, and the end surfaces of the outer shell and the inner rod are not on the same section, under the condition, the second reflecting point is between the end surface of the outer shell and the end surface of the inner rod.

In one embodiment of the present application, the cavity length measuring device is a reflective cavity length measuring device in which:

one end of the sensor is connected with a radio frequency coaxial cable adapter, and the radio frequency coaxial cable adapter is connected with the demodulation main board through a coaxial cable; or one end of the sensor is directly connected to the demodulation mainboard, namely one end of the sensor can be connected to the demodulation mainboard through the first radio frequency coaxial cable adapter, and can also be directly connected to the demodulation mainboard; or the demodulation mainboard is directly connected to a coaxial radio frequency adapter penetrating through the shell wall, and the coaxial radio frequency adapter is provided with a conductor inserted into the shell;

the other end of the sensor is a second reflection point and a conductor reflection surface.

In one embodiment of the present application, the cavity length measuring device is a transmissive cavity length measuring device in which:

one end of the sensor is connected with a first radio frequency coaxial cable adapter, the shell wall of the sensor is connected with a second radio frequency coaxial cable adapter, one end of the demodulation mainboard is connected with the first radio frequency coaxial cable adapter through a coaxial cable, and the other end of the demodulation mainboard is connected with the second radio frequency coaxial cable adapter through a coaxial cable; or,

one end of the sensor is connected with a first radio frequency coaxial cable adapter, and one end of the demodulation main board is connected with the first radio frequency coaxial cable adapter through a coaxial cable; the shell wall of the sensor is directly connected with the demodulation mainboard, namely the shell wall can be connected with the demodulation mainboard through a second radio frequency coaxial cable adapter and can also be directly connected with the demodulation mainboard; or,

one end of the sensor is directly connected to the demodulation main board, namely one end of the sensor can be connected with the demodulation main board through the first radio frequency coaxial cable adapter and can also be directly connected with the demodulation main board; the shell wall of the sensor is connected with a second radio frequency coaxial cable adapter, and the second radio frequency coaxial cable adapter is connected with the demodulation mainboard through a coaxial cable; or,

one end of the sensor is directly connected to the demodulation main board, namely one end of the sensor can be connected with the demodulation main board through the first radio frequency coaxial cable adapter and can also be directly connected with the demodulation main board; the shell wall of the sensor is directly connected with the demodulation mainboard, namely, the shell wall can be connected with the demodulation mainboard through a second radio frequency coaxial cable adapter and can also be directly connected with the demodulation mainboard.

In one embodiment of the present application, when the cavity length measuring device is a transmission-type cavity length measuring device, the cavity length measuring device has at least the following modes: a positive feedback loop mode, a loop-free mode; wherein,

in the positive feedback loop mode, the demodulation main board includes: a directional coupler, a waveform amplifier, a frequency counter/frequency spectrograph;

in the loop-free mode, the demodulation main board is a vector network analyzer, or a microwave generating source plus a scalar network analyzer, or a microwave time domain reflectometer, or a demodulation circuit board for demodulating a frequency spectrum.

In one embodiment of the present application, the positive feedback loop mode comprises: a microwave positive feedback loop and a positive feedback loop based on a photoelectric oscillator; wherein,

in the microwave positive feedback loop, comprising: the demodulation main board comprises a coaxial cable loop, a microwave directional coupler, a microwave amplifier or a microwave power separator, wherein all devices in the demodulation main board are connected through the coaxial cable loop;

in the optoelectronic oscillator based positive feedback loop, comprising: the high-speed optical fiber demodulation device comprises a high-speed photoelectric demodulator, a laser or light emitting diode light source, an optical fiber loop, an optical fiber coupler, a microwave amplifier or an optical amplifier, a microwave directional coupler or a microwave power separator, wherein all devices in the demodulation main board are connected through the optical fiber loop.

In one embodiment of the present application, the sensor has therein: the shell or the shell is provided with an inner rod and a conductor reflecting surface; wherein the housing is formed of a continuous conductor, the inner rod is formed of a continuous conductor, the conductor reflecting surface is formed of a continuous conductor, and the continuous conductor is: a single conductive part, or a plurality of conductive parts connected together, or a conductor plating on an insulator, the conductive part being made of a conductive material at least comprising: metal, non-metal; the non-metals include at least: graphite, or carbon fiber, or conductive ceramics;

the shape of the conductor reflecting surface is a solid structure, a plane structure or a curved surface structure; the shape of the conductor reflecting surface is a pore structure, or a circular structure, or a long-strip-shaped structure, or formed by splicing a plurality of conductors, or formed by splicing a conductor and an insulator; the conductor reflecting surface is made of a single conductor material, or different conductor materials, or a part of conductor material and a part of insulator material; the conductor area of the conductor reflecting surface is continuous or discontinuous;

the conductor reflecting surface meets the following requirements: ensuring that a column swept out along the axial direction by the envelope surfaces of the outer shell and the inner rod has an intersection with the area where the conductor reflecting surface is located, wherein the conductor reflecting surface is perpendicular or not perpendicular to the axial line of the outer shell and the inner rod; the conductor reflecting surface is a plane or a curved surface;

the change of the end face distance between the conductor reflecting surface and the second reflecting point is realized by at least one of the following modes: movement of the conductor reflective surface; deformation of the conductor reflective surface; the refractive index of the dielectric medium between the conductor reflecting surface and the second reflecting point is changed;

the size of the conductor reflecting surface is larger than or equal to the diameter of the shell, and the end surface of the shell is fully covered; alternatively, the conductor reflecting surface is smaller in size than the diameter of the housing.

In one embodiment of the present application, the cross-section of the housing is a closed shape or a non-closed shape;

in the case of the sensor comprising a housing plus an inner rod:

the outer shell wraps the inner rod, or the outer shell does not wrap the inner rod;

the shell and the inner rod are two conductor coatings on one plane, or two conductor parallel rods in space;

the outer shell is coaxial with the inner rod, or the outer shell is not coaxial with the inner rod.

In one embodiment of the present application, in the open hollow coaxial cable-fabry-perot resonator between the first reflection point and the second reflection point, and between the outer shell and the inner rod, the filled medium is one of the following: vacuum, gas, liquid, solid;

in the dielectric cavity between the second reflection point and the conductor reflection surface, the filled medium is one of the following: vacuum, gas, liquid, solid.

In one embodiment of the present application, the first reflective dot and the second reflective dot are disposed between the outer shell and the inner rod; the second reflection point is an end face of the outer shell or the inner rod; or when the outer shell and the inner rod are not in contact with the conductor reflecting surface and the lengths of the outer shell and the inner rod are different, the second reflecting point is between the end surface of the outer shell and the end surface of the inner rod; wherein,

the insulator or the conductor with the resistivity greater than or equal to a preset threshold is solid, liquid or gas; for one or both of the first reflection point and the second reflection point, the reflection point may be a conductor or an insulator, and the reflection point and the outer shell and the inner rod satisfy the following positional relationship:

the reflecting point is connected with the outer shell and the inner rod through conductors with the resistivity smaller than a preset threshold value; or,

the reflecting point is not contacted with the shell, or is connected with the insulator, or is connected with a conductor with the resistivity more than or equal to a preset threshold value, and the reflecting point is connected with a conductor with the resistivity less than the preset threshold value for the inner rod; or,

the reflecting point is not contacted with the inner rod, or is connected with the insulator, or is connected with a conductor with the resistivity more than or equal to a preset threshold value, and the reflecting point is connected with a conductor with the resistivity less than the preset threshold value for the shell; or,

the reflecting point is not in contact with the outer shell and the inner rod, or is connected with an insulator, or is connected with a conductor with the resistivity more than or equal to a preset threshold value;

the second reflection point and the conductor reflection surface satisfy the following positional relationship:

the shell and the inner rod are not in contact with the conductor reflecting surface, or are connected by an insulator, or are connected by a conductor with the resistivity larger than or equal to a preset threshold value, and when the end surfaces of the conductor areas of the shell and the inner rod are in the same plane, the second reflecting point is the common end surface of the shell and the inner rod; or,

the shell and the inner rod are not in contact with the conductor reflecting surface, or are connected by an insulator, or are connected by a conductor with the resistivity larger than or equal to a preset threshold value, and when the end surfaces of the conductor areas of the shell and the inner rod are not the same plane, the second reflecting point is a point between the end surface of the shell and the end surface of the inner rod; or,

the shell is connected with the conductor reflecting surface by a conductor with the resistivity smaller than a preset threshold, and the second reflecting point is the end surface of the inner rod when the inner rod is not contacted with the conductor reflecting surface, or is connected by an insulator, or is connected by a conductor with the resistivity larger than or equal to the preset threshold; or,

the shell is not contacted with the conductor reflecting surface, or is connected with the insulator, or is connected with the conductor with the resistivity more than or equal to the preset threshold, and when the inner rod is connected with the conductor with the resistivity less than the preset threshold, the second reflecting point is the end surface of the shell.

In one embodiment of the present application, in a reflective cavity length measuring device:

when the sensor comprises a shell and an inner rod, the first ends of the shell and the inner rod are both connected with the radio-frequency coaxial cable adapter, and the radio-frequency coaxial cable adapter is connected with the demodulation main board through a coaxial cable; or the first ends of the outer shell and the inner rod are directly connected with the demodulation main board, namely the first ends of the outer shell and the inner rod can be connected with the demodulation main board through a first radio frequency coaxial cable adapter or directly connected with the demodulation main board; at least one part of the first reflection point and the second reflection point is arranged in the envelope range of the shell and the inner rod;

when the sensor only has a shell and does not have an inner rod, the first end of the shell is connected with the radio frequency coaxial cable adapter, and the radio frequency coaxial cable adapter is connected with the demodulation main board through a coaxial cable; or the first end of the shell is directly connected with the demodulation mainboard, namely the first end of the shell can be connected with the demodulation mainboard through the first radio frequency coaxial cable adapter, and can also be directly connected with the demodulation mainboard; the first reflection point and the second reflection point are disposed within an envelope of the housing.

In one embodiment of the present application, in a transmissive cavity length measuring device, the cavity length measuring device has at least the following modes: positive feedback loop mode, loop-free mode:

when the sensor comprises an outer shell and an inner rod, the first ends of the outer shell and the inner rod are both connected with a first radio frequency coaxial cable adapter, and the first radio frequency coaxial cable adapter is connected to the demodulation main board through a first coaxial cable; or the first ends of the outer shell and the inner rod are directly connected with the demodulation main board, namely the first ends of the outer shell and the inner rod can be connected with the demodulation main board through a first radio frequency coaxial cable adapter or directly connected with the demodulation main board; the shell wall is connected with a second radio frequency coaxial cable adapter, and the second radio frequency coaxial cable adapter is connected to the demodulation main board through a second coaxial cable; or the shell wall is directly connected with the demodulation mainboard, namely the shell wall can be connected with the demodulation mainboard through a second radio frequency coaxial cable adapter, and can also be directly connected with the demodulation mainboard; at least one part of the first reflection point and the second reflection point is arranged in the envelope range of the shell and the inner rod;

when the sensor is only provided with the shell and does not have the inner rod, the first end of the shell is connected with a first radio frequency coaxial cable adapter, and the first radio frequency coaxial cable adapter is connected to the demodulation main board through a first coaxial cable; or the first end of the shell is directly connected with the demodulation mainboard, namely the first end of the shell can be connected with the demodulation mainboard through the first radio frequency coaxial cable adapter, and can also be directly connected with the demodulation mainboard; the shell wall is connected with a second radio frequency coaxial cable adapter, and the second radio frequency coaxial cable adapter is connected to the demodulation main board through a second coaxial cable; or the shell wall is directly connected with the demodulation mainboard, namely the shell wall can be connected with the demodulation mainboard through a second radio frequency coaxial cable adapter, and can also be directly connected with the demodulation mainboard; at least a portion of the first reflection point and the second reflection point are disposed within an envelope of the housing;

the second radio frequency coaxial cable adapter is arranged between the first reflection point and the second reflection point.

In one embodiment of the present application, the first reflection point is a conductor and is connected to both the inner rod and the outer shell, so as to short-circuit the inner rod and the outer shell; the second reflection point is the end surface of the outer shell or the inner rod;

when the outer shell is in a closed shape, the inner shape of the outer shell is circular or rectangular, the section of the inner rod is also circular or rectangular, the first reflection point forms a short circuit between the outer shell and the inner rod, and the second reflection point is high reflection formed by the disconnection of the end surface of the outer shell or the inner rod;

the first reflection point is a cross section with the size smaller than a preset area, and can be at least vertically placed in the axis direction of the inner rod of the sensor through one or more round rods or square rods, or a porous structure with certain transmittance is fixed between the outer shell and the inner rod, and the area of the area, covered between the outer shell and the inner rod, of the first reflection point is smaller than the envelope area between the outer shell and the inner rod; the first reflection point forms a short circuit between the outer shell and the inner rod, or the resistance of a connecting piece between the outer shell and the inner rod is larger than or equal to a preset threshold value, or no connecting piece exists between the outer shell and the inner rod; the second reflection point is a point between the end surface of the shell, or the end surface of the inner rod, or the end surface of the shell conductor region and the end surface of the inner rod conductor region; the conductor reflecting surface is connected with the conductor with the resistivity smaller than a preset threshold value when the outer shell and the inner rod are not used simultaneously;

the positions of the first reflection point and the second reflection point are fixed, and the measurement of displacement, strain, pressure, angle, liquid level or flow speed can be realized by changing the distance between the conductor reflection surface and the second reflection point; wherein the distance between the conductor reflecting surface and the second reflecting point is changed by at least one of the following modes: movement of the conductive reflective surface, deformation of the conductive reflective surface, a change in refractive index of a medium between the conductive reflective surface and the second reflection point.

In one embodiment of the present application, the reflectivity is adjusted by changing the shape and size of the cross section of the inner rod, so that a first reflection point added between the outer shell and the inner rod can be removed, and the joint of the radio frequency coaxial cable adapter and the outer shell and the inner rod is used as the first reflection point; when the radio frequency coaxial cable adapter is taken as a first reflection point at the joint of the outer shell and the inner rod, the ratio of the diameter of the inner rod to the inner diameter of the outer shell is between 0 and 1; or,

arranging a first reflection point at the position where the shell and the inner rod are connected with a radio frequency coaxial cable adapter; or, the first reflection point is arranged at the position where the shell and the inner rod are connected with the demodulation circuit board of the demodulation frequency spectrum, wherein the first end faces of the shell and the inner rod are directly connected with the demodulation circuit board, or the first end faces of the shell and the inner rod are connected with the demodulation circuit board through a radio frequency coaxial cable adapter.

In one embodiment of the present application, the cavity length measuring device is applied in a pressure sensor;

one end of the outer shell and one end of the inner rod are connected with a demodulation device; the other end of the shell is connected with a diaphragm, the connecting material is a conductor or an insulator, and the diaphragm is a conductor or a conductor coating film is arranged on the first side surface of the diaphragm; the first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end surface of the outer shell or the inner rod, and the first reflection point and the second reflection point are fixed points; the first side surface of the diaphragm close to the shell and the inner rod is a conductor reflecting surface; the end face of the inner rod is not contacted with the first side face of the diaphragm, or is connected with an insulator, or is connected with a conductor with the resistivity more than or equal to a preset threshold value, and a space between the second reflecting point and the reflecting surface of the conductor is a dielectric cavity; the second side surface of the diaphragm is a pressed surface, a certain distance is reserved between the diaphragm and the end surface of the inner rod, the diaphragm is in a non-contact state, or liquid or solid with the resistivity smaller than a preset threshold value is used for filling, namely gas, liquid or solid is filled in the cavity of the dielectric cavity; when the pressure intensity is changed, the deflection of the diaphragm is changed, the distance between the second reflection point and the first side surface of the diaphragm is changed, namely the cavity length of the dielectric cavity is changed, so that the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the cavity length variation of the dielectric cavity is determined according to the resonant frequency/the resonant cavity length variation of the open type hollow coaxial cable-Fabry-Perot resonant cavity, so that the pressure intensity is determined; after the diaphragm deforms, the first side surface changes from a plane to a curved surface, wherein the deflection variation of the diaphragm is influenced by the deflection of each point of the diaphragm, and the deflection variation of the diaphragm is between the minimum deflection and the maximum deflection;

wherein, the sensitivity of the pressure sensor can be increased by the following modes: firstly, the initial distance between the first side face of the diaphragm and the second reflection point is reduced; secondly, the thickness of the membrane is reduced; thirdly, the diameter of the diaphragm is increased, the inner diameter and the outer diameter of the end face of the shell are increased, the diaphragm with the diameter larger than or equal to the diameter of the shell is connected to the outer ring of the end face of the diameter expanding structure, and the outer ring of the diaphragm is connected with the end face of the diameter expanding structure in a sealing mode.

one end of the outer shell and one end of the inner rod are connected with a demodulation device; the other ends of the outer shell and the inner rod are cut end surfaces and are not connected with any object; the first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end surface of the outer shell or the inner rod, and the first reflection point and the second reflection point are fixed points; the pressure intensity is measured by adopting the Bourdon tube, and a certain movement amount is generated on the end face of the Bourdon tube or one point on the Bourdon tube; aiming at the movement of the point A on the Bourdon tube, a conductor reflecting surface is fixedly connected to the point A, the conductor reflecting surface is a rigid body, and the normal line of the conductor reflecting surface is parallel to the movement direction of the Bourdon tube at the point A after the pressure intensity is changed; the conductor reflecting surface is not in contact with the end surfaces of the shell and the inner rod, or is connected with an insulator, or is connected with a conductor with the resistivity larger than or equal to a preset threshold value, and has a certain distance; the space between the conductor reflecting surface and the second reflecting point is a dielectric cavity; the normal line of the conductor reflecting surface is parallel to the axes of the outer shell and the inner rod;

fixing the cavity length measuring device and the bourdon tube base of the dielectric cavity on a rigid object, wherein the cavity length measuring device and the bourdon tube base do not move relatively; the normal line of the conductor reflecting surface, the axes of the shell and the inner rod and the moving direction of the point A are all parallel, so when the pressure intensity is changed, the point A on the Bourdon tube moves to drive the conductor reflecting surface to move, the distance between the conductor reflecting surface and the second reflecting point is changed, namely the cavity length of the dielectric cavity is changed, the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the cavity length variable quantity of the dielectric cavity is determined through the resonant frequency/the cavity length variable quantity of the open type hollow coaxial cable-Fabry-Perot resonant cavity, so that the pressure intensity is determined; the types of the Bourdon tube at least comprise a C-shaped Bourdon tube, or a C-shaped combined Bourdon tube, or a spiral Bourdon tube, or a twist Bourdon tube, or a circular Bourdon tube.

In one embodiment of the present application, the cavity length measuring device is applied in an acceleration sensor;

one end of the outer shell and one end of the inner rod are connected with a demodulation device; the other end of the shell is connected with a structure with certain rigidity, the structure at least comprises a diaphragm or a beam, and the connecting material is a conductor or an insulator; the first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end surface of the outer shell or the inner rod, and the first reflection point and the second reflection point are fixed points; the first side surface of the diaphragm or the beam close to the shell and the inner rod is a conductor reflecting surface; the end face of the inner rod is connected with the first side face of the diaphragm or the beam without a conductor and has a certain distance; a mass block with mass m is fixed at the center of the second side face of the diaphragm or the beam, and when the acceleration is a, the mass block can generate force F (F is ma) on the diaphragm or the beam to change the deflection of the central point of the diaphragm or the beam, so that the distance between the conductor reflecting surface and the second reflecting point is changed, namely the cavity length of the dielectric cavity is changed, and finally the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed;

the diameter of the diaphragm or the length of the beam is equal to the outer diameter of the shell or the outer diameter of an expanded diameter area of the end face of the shell, the thickness of the diaphragm or the rigidity of the beam is increased, the weight of the mass block is reduced, the sensitivity of the acceleration sensor is reduced, and the acceleration sensor is suitable for measuring wide-range acceleration; the diameter of the diaphragm is enlarged or the length of the beam is increased, the thickness of the diaphragm or the rigidity of the beam is reduced, the weight of the mass block is increased, the sensitivity of the acceleration sensor is increased, and the acceleration sensor is suitable for measuring small-range acceleration; when the diameter of the diaphragm is increased, the diameter can be increased by adding an expanding structure on the end face of the shell, the expanding structure at least comprises a bell mouth or a conductor with the expanded diameter, and the outer ring of the diaphragm is hermetically connected with the end face of the expanding structure; when the length of the beam is increased, the end surface of the shell is respectively added with a cantilever support to two sides along the diameter direction, the end surfaces of the two supports are used as two fulcrums of the beam and are connected by adopting a connecting piece, and the two ends are rigidly connected or are made into a simply supported beam with two hinged ends; or the cantilever beam is made, a mass block is fixed on the end face of the cantilever beam, and a conductor reflecting surface is arranged on one side of the mass block close to the end faces of the shell and the inner rod.

In one embodiment of the present application, the cavity length measuring device is applied to a flow rate sensor, and the flow rate sensor is a first flow rate sensor or a second flow rate sensor;

in the first flow velocity sensor, a pressure sensor is used for modification, the flow velocity is obtained by measuring the pressure intensity by utilizing the difference of the pressure intensities generated by different flow velocities; the flow velocity sensor at least comprises a plate hole flow velocity sensor or a U-shaped pipe differential pressure flow velocity sensor; under the condition that the fluid moves from left to right, a baffle is fixed beside the pressure sensor, so that additional pressure is generated when the fluid impacts the baffle, the additional pressure on the left side of the baffle is measured by using the pressure sensor fixed on the left side of the baffle, and the flow speed is determined according to the additional pressure;

in the second flow velocity sensor, a first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, a second reflection point is the end surface of the outer shell or the inner rod, and the first reflection point and the second reflection point are fixed points; when the flow rates are different, the thrust on the probe inserted into the fluid on the end face of the probe is different, so that the moving distance of the probe is changed, one point on the probe rotates around a hinge, the hinge is fixed on a shell of the sensor through a connecting part, the other end of the probe is connected with a conductor reflecting surface, and the conductor reflecting surface is not contacted with the end face of the inner rod, or is connected by an insulator, or is connected by a conductor with the resistivity more than or equal to a preset threshold value; wherein, in the first structure of the second flow rate sensor: the conductor reflecting surface is connected with the shell by an elastic material, and the elastic material is a conductor or an insulator; during measurement, the probe is driven to rotate by the movement of the probe, so that the other end of the probe is driven to move reversely, the conductor reflecting surface is driven to move, and the elastic material between the conductor reflecting surface and the shell is stretched or compressed, so that the distance from the conductor reflecting surface to a second reflecting point is changed, namely the cavity length of the dielectric cavity is changed; the larger the flow velocity is, the larger the thrust generated to the probe is, the larger the stretching or compressing amount of the flexible conductor material is, and the larger the cavity length variation of the dielectric cavity is, so that the larger the resonant frequency/resonant cavity length variation of the coaxial cable-Fabry-Perot resonant cavity is; in a second structure of the second flow rate sensor: the shell is connected with a membrane, the second reflection point is the end surface of the inner rod, the carrier of the conductor reflection surface is the membrane, the force generated by the fluid pushing probe drives the other end of the probe rod to move reversely, the central point of the membrane is extruded through a hinged part connected with the carrier of the second reflection point, so that the deflection of the membrane is changed, the cavity length of the dielectric cavity is changed, and the resonant frequency/the resonant cavity length of the coaxial cable-Fabry-Perot resonant cavity is changed; the first structure and the second structure determine the cavity length variation of the dielectric cavity through the resonance frequency/cavity length variation of the open type hollow coaxial cable-Fabry-Perot resonant cavity, so that the flow rate is determined.

In one embodiment of the present application, the cavity length measuring device is used in a force gauge, the force gauge being a first force gauge or a second force gauge;

the first dynamometer is a dynamometer made by using the rigidity and flexibility of a beam or a diaphragm of an end face of a shell; one end of the outer shell and one end of the inner rod are connected with a demodulation device; the other end of the shell is connected with a structure with certain rigidity, the structure at least comprises a diaphragm or a beam, and the connecting material is a conductor or an insulator; the first reflection point is fixed between the end faces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end face of the outer shell or the inner rod, and the first reflection point and the second reflection point are fixed points, so that the distance variation between the second reflection point and the conductor reflection face is equal to the distance variation between the first reflection point and the conductor reflection face; the first side surface of the diaphragm or the beam close to the shell and the inner rod is a conductor reflecting surface; the end surface of the inner rod is connected with the dielectric cavity between the first side surfaces of the diaphragms or the beams without a conductor, and a certain distance is reserved between the end surface of the inner rod and the first side surfaces of the diaphragms or the beams; when the central point of the diaphragm or the beam is subjected to an acting force F, the deflection of the central point of the diaphragm or the beam is changed, so that the distance between the conductor reflecting surface and the second reflecting point is changed, namely the cavity length of the dielectric cavity is changed, the resonant frequency/the cavity length of the resonant cavity of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, the cavity length variation of the dielectric cavity is determined through the resonant frequency/the resonant cavity length variation of the open type hollow coaxial cable-Fabry-Perot resonant cavity, and the force is determined;

a second dynamometer, which is made using rigidity and deformation of a case; one end of the outer shell and one end of the inner rod are connected with a demodulation device; the other end of the shell is connected with a conductor reflecting surface, and the thickness of a carrier of the conductor reflecting surface is more than or equal to a preset threshold value; the first reflection point is fixed between the end faces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end face of the inner rod, and the first reflection point and the second reflection point are fixed points, so that the distance variation between the second reflection point and the conductor reflection surface is equal to the distance variation between the first reflection point and the conductor reflection surface; the conductor reflecting surface is fixed with the shell and is not contacted with the inner rod, and a certain distance is reserved between the second reflecting point and the conductor reflecting surface; when a carrier of the conductor reflecting surface is subjected to tensile force or pressure, the shell can be stretched or compressed, the elasticity of the shell material is E, the net area is A, the distance from the first reflecting point to the conductor reflecting surface is L, after the shell is stressed, the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, the variable quantity of the distance between the conductor reflecting surface and the end surface of the inner rod is determined based on the variable quantity of the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, namely the cavity length variable quantity of the dielectric cavity is delta d, and the obtained acting force is F & EA & delta d/L.

In one embodiment of the present application, the cavity length measuring device is applied in a strain gauge;

the sensor is internally provided with a first reflection point, a second reflection point and a conductor reflection surface, the first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end surface of the outer shell or the inner rod, and the first reflection point and the second reflection point are fixed points; the structure of the shell external fixing bulge at the first reflection point is used as a first fixing point, the structure of the shell external fixing bulge at the conductor reflection surface is used as a second fixing point, and the distance between the first fixing point and the second fixing point is L; the second reflecting point is the end surface of the inner rod and is at a certain distance from the conductor reflecting surface, the second reflecting point is not in contact with the conductor reflecting surface, and the middle part of the second reflecting point is a dielectric cavity, or solid or liquid is filled in the dielectric cavity between the second reflecting point and the conductor reflecting surface; one end of the shell and the inner rod or the shell wall of the shell are connected with a demodulation device; the shell is segmented and is composed of two sections of conductor materials, the two sections of conductor materials are connected by adopting a nested structure or a conductor corrugated pipe, or the shell is not segmented, and when the strain changes, the shell material is stretched or compressed; the inner rod is a rigid body and is not segmented, and the second reflection point is the end face of the inner rod;

the strain gauge can be fixed to the object to be detected or embedded in the medium to be detected by the first fixing point and the second fixing point, when the object or medium to be detected is strained, the first fixed point and the second fixed point can be driven to move relatively, so that the first reflection point and the conductor reflection surface are driven to move relatively by delta d, since the distance between the first reflection point and the second reflection point is fixed, the relative displacement between the first reflection point and the conductor reflection surface is equal to the relative displacement between the second reflection point and the conductor reflection surface, that is, the cavity length of the dielectric cavity changes, and the cavity length change amount Δ d of the dielectric cavity can be obtained through the resonant frequency/cavity length change amount of the open type hollow coaxial cable-fabry-perot resonant cavity, so that the magnitude of the strain is ∈ ═ Δ d/L.

In one embodiment of the present application, the cavity length measuring device is applied in a single direction inclinometer; a cavity length measuring device for measuring the dielectric cavity is adopted to be made into a one-way inclinometer;

the sensor is internally provided with a first reflection point, a second reflection point and a conductor reflection surface, the first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point is the end surface of the outer shell and the inner rod, and the first reflection point and the second reflection point are fixed points; the shell is fixed with a bracket used for hanging a flexible rope or an elastic rod with two hinged ends, and a heavy object is hung below the flexible rope or the elastic rod with two hinged ends; the first end surfaces of the heavy object, which are close to the end surfaces of the shell and the inner rod, are conductor reflecting surfaces made of conductor materials; when the measured object drives the inclinometer to incline, the support and the second reflecting point incline along with the measured object, the conductor reflecting surface and the heavy object keep the original state or only rotate under the action of gravity, so that the conductor reflecting surface and the heavy object can move relative to the second reflecting point, the distance between the conductor reflecting surface and the second reflecting point is changed, namely the cavity length of the dielectric cavity is changed, finally the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the size of the inclination angle is determined through the variable quantity of the resonant frequency/the cavity length;

when the conductor reflecting surface is placed in parallel with the end surface corresponding to the second reflecting point, the following first working condition adopts two or more flexible ropes with equal length or elastic rods with hinged ends to hang a heavy object, when the connecting line of the fixed points of the flexible ropes with equal length or the elastic rods with hinged ends on the support is not vertical to the axes of the shell and the inner rod, after the inclination angle is changed, the end surfaces corresponding to the conductor reflecting surface and the second reflecting point are always parallel; in the second working condition, a heavy object is hung by adopting two equal-length flexible ropes which are arranged in front and back, the plane formed by the two flexible ropes, the support and the four fixed points of the heavy object is vertical to the axes of the shell and the inner rod, or the heavy object is hung by the elastic rods with two ends connected rigidly, and after the inclination angle is changed, the included angle between the conductor reflecting surface and the end surface corresponding to the second reflecting point can be changed;

the first working condition is as follows: fixing the inclinometer on a measured object, and using two parallel and equilong flexible ropes placed left and right or elastic rods with two hinged ends, wherein a plane formed by the four connecting points of the flexible ropes or the elastic rods, the support and the heavy object is parallel to the axes of the shell and the inner rod; the elastic rod is hinged with the support and the weight, the length of the flexible rope or the elastic rods hinged with the two ends is L, when the inclination angle of the inclinometer changes on a plane formed by the two flexible ropes or the elastic rods hinged with the two ends, the conductor reflecting surface is always parallel to the end surfaces of the shell and the inner rod, the distance variation between the second reflecting point and the conductor reflecting surface is determined through the resonance frequency/resonant cavity length variation of the open hollow coaxial cable-Fabry-Perot resonant cavity, namely the cavity length variation of the dielectric cavity is delta d, and thus the variation of the inclination angle is delta theta, namely arcsin (delta d/L);

the second working condition is as follows: fixing the inclinometer on a measured object, hanging a heavy object by adopting two equilong flexible ropes which are arranged in front and at the back or elastic rods with two hinged ends, wherein a plane formed by the two flexible ropes or the elastic rods and four fixed points which are directly connected with the heavy object is vertical to the axes of the shell and the inner rod; or the two ends of the elastic rods are rigidly connected, the number of the elastic rods can be one elastic rod, or two elastic rods, or a plurality of elastic rods, the two ends of the elastic rods are rigidly connected with the support and the weight, the length of the flexible rope or the elastic rods with the two ends rigidly connected is L, when the inclination angle of the inclinometer changes, the distance variation between the second reflecting point of the open hollow coaxial cable-Fabry-Perot resonant cavity and the conductor reflecting surface is determined through the resonant frequency/resonant cavity length variation of the open hollow coaxial cable-Fabry-Perot resonant cavity, namely the cavity length variation of the dielectric cavity is delta d, and the relationship between the distance variation delta d and the inclination angle variation delta theta needs to be obtained through calibration.

In one embodiment of the present application, the cavity length measuring device is used in a bi-directional inclinometer;

the cavity length measuring device of two dielectric cavities which are not parallel and horizontally arranged is adopted and respectively and rigidly fixed on the top plate, the bottom surface or the side wall of the inclinometer; the outer shell and the inner rod of the two cavity length measuring devices are arranged on the same end surface, and the end surface is used as a second reflection point; under the first working condition, at least three parallel flexible ropes with equal length or elastic rods with two hinged ends are fixed on the top plate, and the flexible ropes or the elastic rods with two hinged ends are not in the same straight line with all the fixed points of the top plate or the heavy object, and the cavity length variation of the dielectric cavity is only related to the rope length/rod length and the inclination angle and is unrelated to the number and the positions of the ropes or the rods; a weight is hung at the bottom of the flexible rope or the elastic rod with two hinged ends, and vertical surfaces parallel to the flexible rope or the elastic rod with two hinged ends are arranged on the weight and are respectively used as conductor reflecting surfaces of the two cavity length measuring devices and made of conductor materials; in the second working condition, one or more elastic rods are used for rigidly connecting the top plate and the heavy object, and the two conductor reflecting surfaces on the heavy object are not parallel;

the first working condition is as follows: connecting a top plate and a heavy object by using parallel and equal-length flexible ropes or elastic rods hinged at two ends, fixing the inclinometer on a measured object, and using three parallel and equal-length flexible ropes or elastic rods hinged at two ends, namely three flexible ropes or elastic rods hinged at two ends respectively form two triangles with three points connected with the top plate and the heavy object, wherein the length of the flexible ropes or the elastic rods hinged at two ends is L; when the three flexible ropes or two flexible ropes are usedWhen three intersection points of the elastic rod with the hinged end and the top plate are not on the same straight line, the two inclination directions are respectively inclined around an X axis and inclined around a Y axis; a weight is hung below the three ropes, and the normals of two surfaces serving as conductor reflecting surfaces are respectively an X axis and a Y axis; the axes of the cavity length measuring devices of the two dielectric cavities are respectively vertical to the two conductor reflecting surfaces, and the end surfaces of the shells and the inner rod of the two cavity length measuring devices keep a certain distance from the two conductor reflecting surfaces; when the inclinometer inclines around the X axis and the Y axis, the distance between the second reflection point of the two cavity length measuring devices and the conductor reflection surface changes, so that the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity changes, and the distance variation between the second reflection point of the two cavity length measuring devices and the conductor reflection surface can be calculated, namely the cavity length variation of the dielectric cavity is delta d₁And Δ d₂(ii) a The distance between the second reflection point of the first cavity length measuring device and the conductor reflection surface changes by delta d₁And the length L of the rope, the variation delta theta of the inclination angle of the inclinometer around the X axis can be determined₁＝arcsin(Δd₁L); the cavity length variation deltad of the dielectric cavity between the second reflection point of the second cavity length measuring device and the conductor reflection surface₂And the length L of the rope, the variation delta theta of the inclination angle of the inclinometer around the Y axis can be determined₂＝arcsin(Δd₂L); as long as the number of the flexible ropes or the elastic rods hinged at the two ends is more than or equal to 3, all the flexible ropes or the elastic rods hinged at the two ends are equal in length and are arranged in parallel, and the connecting lines of the fixed points of all the flexible ropes or the elastic rods hinged at the two ends and the top plate are not in the same straight line, the inclination angles in two directions can be obtained by using the working condition calculation method; when three or more elastic rods which are not in a straight line with the fixed point of the top plate and are parallel and equal in length are used for connecting the top plate and the heavy object in a hinged mode, the calculation method is the same as that under the first working condition;

the second working condition is as follows: the clinometer is fixed on a measured object by using an elastic rod to rigidly connect the top plate and the heavy object, wherein the length of the elastic rod is L, and the elastic rod is L, or two elastic rods or more than three elastic rods are usedThe rod is rigidly connected with the top plate and the weight; when the inclinometer inclines around the X axis and the Y axis, the distance variation between the second reflecting point and the conductor reflecting surface can be obtained through the resonance frequency/resonant cavity length variation of the two cavity length measuring devices, namely the cavity length variation of the dielectric cavity is delta d₁And Δ d₂The cavity length variation delta d of the two dielectric cavities needs to be obtained through calibration₁、Δd₂And the inclination angle variation amount delta theta₁、Δθ₂The relationship between them.

In one embodiment of the present application, the cavity length measuring device is applied in a single direction inclinometer;

the two pressure sensors are used for manufacturing a one-way inclinometer, the inclinometer comprises a closed container fixed on a measured object, liquid with a certain depth is arranged at the bottom of the closed container, and the inclinometer determines an inclination angle by utilizing the pressure difference value of the two pressure sensors, so that the influence of temperature can be eliminated without temperature compensation;

when the two pressure sensors are rigidly fixed on the top plate, the bottom plate or the side surface in the container, the two pressure sensors rotate along with the inclination of the measured object; the two pressure sensors are placed left and right, the axes of the two pressure sensors are parallel, and the parallel distance between the two axes is d; the end surfaces of the outer shell and the inner rod are arranged below the outer shell, and the two pressure measuring diaphragms or Bourdon tube end diaphragms are immersed in liquid and are equal to the bottom of the container; when the object to be measured drives the closed container to incline in a plane formed by the axes of the two pressure sensors, the depth of the two pressure sensors immersed in the liquid can change, so that the pressure measured by the two pressure sensors can also change; the axes of the two pressure sensors are always parallel, so that the distance between the axes of the two pressure sensors can also change along with the change of the inclination angle; determining the variation DeltaL of the immersion depth by the pressure variation of the two pressure sensors₁And Δ L₂Finally, the amount of change in the tilt angle Δ θ ═ arctan [ (Δ L) is obtained₂-ΔL₁)/d]；

When the tops of two left and right pressure sensors are hinged through a flexible rope or two endsWhen the elastic rod is connected to a top plate in the container, the distance between two fixed points is d, and under the action of gravity, the axes of the two pressure sensors are always vertical and do not rotate along with the inclination of the measured object; the end surfaces of the outer shell and the inner rod are arranged below the outer shell, and the two pressure measuring diaphragms or Bourdon tube end diaphragms are immersed in liquid and are equal to the bottom of the container; when the object to be measured drives the closed container to incline in a plane formed by the axes of the two pressure sensors, the depth of the two pressure sensors immersed in the liquid also changes, so that the pressure measured by the two pressure sensors also changes, and the variation delta L of the immersion depth is calculated according to the variation of the pressure of the two pressure sensors₁And Δ L₂Finally, the degree change amount of the inclination angle is Δ θ ═ arcsin [ (Δ L)₂-ΔL₁)/d]。

the three pressure sensors are used for manufacturing a bidirectional inclinometer, the inclinometer comprises a closed container fixed on a measured object, liquid with a certain depth is arranged at the bottom of the closed container, and the inclination angle is determined by utilizing the pressure difference values of the three pressure sensors after the inclination, so that the influence of temperature can be eliminated, and temperature compensation is not needed;

when the three pressure sensors are rigidly fixed inside the container, the three pressure sensors rotate along with the inclination of the measured object; the three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the pressure measuring diaphragms or Bourdon tube end face diaphragms of the three pressure sensors are immersed in the liquid and are equal to the bottom of the container; when three intersection points of the axes of the three pressure sensors and the horizontal plane form a right triangle, two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a The first pressure sensor and the second pressure sensor are arranged after the inclinometer tilts around the X axis and the Y axisThe depth of the two pressure sensors immersed in the liquid is also changed, so that the pressures measured by the two pressure sensors are also changed, and the variation delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₁And Δ L₂According to the parallel spacing d₁Can determine the variation of the inclination angle of the inclinometer around the X axis as delta theta₁＝arctan[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the variation of the inclination angle of the inclinometer around the Y axis as delta theta₂＝arctan[(ΔL₃-ΔL₂)/d₂]；

When the tops of the three pressure sensors are connected to a top plate in the container through flexible ropes or elastic rods hinged to two ends of the three pressure sensors, under the action of gravity, the axes of the three pressure sensors are always vertical and do not rotate along with the inclination of a measured object; the three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the pressure measuring diaphragms or Bourdon tube end face diaphragms of the three pressure sensors are immersed in the liquid and are equal to the bottom of the container; when the three intersection points of the axes of the three pressure sensors and the top plate form a right triangle, the two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a When the inclinometer inclines around the X axis and the Y axis, the depth of the first pressure sensor and the second pressure sensor immersed in the liquid changes, so that the pressures measured by the two pressure sensors change, and the variation delta L of the immersion depth is calculated according to the pressure variation of the two pressure sensors₁And Δ L₂According to the parallel spacing d₁Can determine the variation delta theta of the inclination angle of the inclinometer around the X axis₁＝arcsin[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the inclination angle variation delta theta of the inclinometer around the Y axis₂＝arcsin[(ΔL₃-ΔL₂)/d₂]。

In one embodiment of the present application, the cavity length measuring device is applied in a slip meter;

a cavity length measuring device of two dielectric cavities is used for making a slippage meter for measuring unidirectional horizontal slippage and longitudinal separation; the medium A is equivalent to the relative displacement of the medium B in the axial direction and the normal direction, wherein the medium A is fixed with a slippage meter carrier, and the medium B is fixed with a double-bevel carrier; the two cavity length measuring devices are respectively a first cavity length measuring device and a second cavity length measuring device, the end surfaces of the shell of each cavity length measuring device and the inner rod conductor region are on a plane, the plane is a plane where the second reflection point is located, and the plane is parallel to the conductor reflection surface; the two inclined holes are fixed on the sliding meter carrier on the medium A and respectively pass through and fix the shells of the first cavity length measuring device and the second cavity length measuring device, and the axes of the two inclined holes are vertical to the two inclined planes; the double inclined planes are inclined planes made of two conductor materials of a double inclined plane carrier fixed on the medium B and are respectively a first inclined plane and a second inclined plane, and the two inclined planes of the double inclined planes are respectively a first conductor reflecting plane and a second conductor reflecting plane corresponding to the first cavity length measuring device and the second cavity length measuring device;

the slippage meter carrier is fixed on the medium A, the shell of the first cavity length measuring device is fixed in a first inclined hole of the slippage meter carrier, the shell of the second cavity length measuring device is fixed in a second inclined hole of the slippage meter carrier, and the end surfaces of the shell and the inner rod of the first cavity length measuring device are opposite to and parallel to the first inclined holeThe end surfaces of the outer shell and the inner rod of the second cavity length measuring device are opposite to and parallel to a second inclined surface, the first inclined surface and the second inclined surface are two inclined surfaces of a double-inclined-surface carrier, and the double-inclined-surface carrier is fixed on a medium B; a second-order matrix formed by normal vectors of the two inclined planes

Is equal to 2, wherein the normal vector of the first slope is (l)₁,n₁)^TThe normal vector of the second inclined plane is (l)₂,n₂)^TThe angle of inclination theta of the two inclined planes with respect to the horizontal plane₁And theta₂Between-90 ° and 90 °;

the first cavity length measuring device is used for measuring the distance variation between the second reflecting point of the device and the reflecting surface of the first conductor, namely the cavity length variation of the dielectric cavity is delta d₁The second cavity length measuring device is used for measuring the distance variation between a second reflecting point of the device and a reflecting surface of the second conductor, namely the cavity length variation of the dielectric cavity is delta d₂(ii) a Two distance variations, i.e. the cavity length variation of the dielectric cavity Δ d₁And Δ d₂The resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity can be obtained; by the cavity length variation of the two dielectric cavities and the normal vectors of the two inclined planes, the horizontal slippage amount Δ x and the longitudinal separation amount Δ z of the medium a relative to the medium B can be obtained:

a cavity length measuring device with three dielectric cavities is used for making a slippage meter for measuring bidirectional horizontal slippage and longitudinal separation; aiming at relative displacement of a medium A, which is equivalent to a medium B in two directions of a plane and in a normal direction, wherein the medium A is fixed with a slippage meter carrier, and the medium B is fixed with a three-inclined-plane carrier; the three cavity length measuring devices are respectively a first cavity length measuring device, a second cavity length measuring device and a third cavity length measuring device, the end surfaces of the shell and the inner rod conductor region of each cavity length measuring device are on a plane, the plane is a plane where the second reflection point is located, and the plane is parallel to the conductor reflection surface; the three inclined holes are fixed on the medium A and are used for fixing the shells of the first cavity length measuring device, the second cavity length measuring device and the third cavity length measuring device respectively, and the axes of the three inclined holes are vertical to the three inclined planes; the three inclined planes are made of three conductor materials fixed on a three-inclined-plane carrier on the medium B and respectively comprise a first inclined plane, a second inclined plane and a third inclined plane, and the three inclined planes of the three inclined planes respectively comprise a first conductor reflecting plane, a second conductor reflecting plane and a third conductor reflecting plane which correspond to the first cavity length measuring device, the second cavity length measuring device and the third cavity length measuring device;

the sliding meter carrier is fixed on the medium A, the shell of the first cavity length measuring device is fixed in a first inclined hole of the sliding meter carrier, the shell of the second cavity length measuring device is fixed in a second inclined hole of the sliding meter carrier, the shell of the third cavity length measuring device is fixed in a third inclined hole of the sliding meter carrier, the end surfaces of the shell of the first cavity length measuring device and the inner rod are opposite and parallel to a first inclined surface, the end surfaces of the shell of the second cavity length measuring device and the inner rod are opposite and parallel to a second inclined surface, the end surfaces of the shell of the third cavity length measuring device and the inner rod are opposite and parallel to a third inclined surface, the first inclined surface, the second inclined surface and the third inclined surface are three inclined surfaces of a three-inclined-surface carrier, and the three-inclined-surface carrier is fixed on the medium B; the third-order matrix formed by the normal vectors of the three inclined planes

Is equal to 3, wherein the normal vector of the first slope is (l)₁,m₁,n₁)^TThe normal vector of the second inclined plane is (l)₂,m₂,n₂)^TThe normal vector of the third inclined plane is (l)₃,m₃,n₃)^TThe inclination angles of the three inclined planes with respect to the horizontal planeDegree theta₁、θ₂And theta₃Between-90 ° and 90 °;

the first cavity length measuring device is used for measuring the distance variation between the second reflecting point of the device and the reflecting surface of the first conductor, namely the cavity length variation of the dielectric cavity is delta d₁The second cavity length measuring device is used for measuring the distance variation between a second reflecting point of the device and a reflecting surface of the second conductor, namely the cavity length variation of the dielectric cavity is delta d₂The third cavity length measuring device is used for measuring the distance variation from the second reflecting point of the device to the reflecting surface of the third conductor, namely the cavity length variation of the dielectric cavity is delta d₃(ii) a Three distance variations, i.e. the cavity length variation of the dielectric cavity Δ d₁、Δd₂And Δ d₃The resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity can be obtained; by the cavity length variation amounts of the three dielectric cavities and the normal vectors of the three slopes, the horizontal slippage amounts Δ x, Δ y and the longitudinal separation amount Δ z of the first object relative to the second object can be obtained:

in one embodiment of the present application, the cavity length measuring device is applied in a spring and diaphragm based displacement sensor;

the displacement sensor converts a large displacement variable quantity into a small diaphragm deflection variable quantity through a spring and a diaphragm; one side of the diaphragm, which is close to the cavity length measuring device of the dielectric cavity, is a conductor reflecting surface; a cavity length measuring device of the dielectric cavity for measuring the distance from the second reflection point to the conductor reflection surface is used for manufacturing a displacement sensor, the shell of the cavity length measuring device and the left end surface of the inner rod are connected with a demodulating device, the right end surface is the second reflection point, a diaphragm is arranged at a certain distance on the right side of the second reflection point, the diaphragm is overlapped with the axis of the inner rod in the shell, and the left end surface of the diaphragm is the conductor reflection surface; the right end face of the diaphragm is connected with a push rod which pushes against the central point of the diaphragm, a supporting and blocking structure is arranged on the right side of the push rod, a spring is arranged on the right side of the supporting and blocking structure, and a probe rod with the supporting and blocking structure is arranged on the right side of the spring;

when the displacement changes, the probe rod moves, the compression amount of the spring changes, the elastic force changes, the force acting on the diaphragm changes through the push rod, and finally the deflection of the diaphragm changes, so that the distance between the conductor reflecting surface and the second reflecting point changes, namely the cavity length of the dielectric cavity changes, and finally the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity changes, and the relation between the resonant frequency/the resonant cavity length and the displacement can be obtained through calibration;

when the end face of the shell is provided with a flaring, the sensitivity of the displacement sensor can be increased by enlarging the diameter of the diaphragm.

In one embodiment of the present application, the cavity length measuring device is applied to a displacement sensor based on a bevel structure;

the inclined plane is used as a conductor reflecting surface, and the axes of the outer shell and the inner rod of the cavity length measuring device are vertical to the inclined plane; an included angle theta is formed between the inclined plane and the horizontal displacement direction measured by the displacement meter, the range of theta is between minus 90 degrees and 90 degrees, namely the inclined plane can incline leftwards and also can incline rightwards, the axis of the displacement meter is always vertical to the inclined plane, the larger the measuring range of the displacement meter is, the smaller the theta is; when the displacement changes, the inclined plane changes the larger displacement variation quantity in the horizontal direction into the smaller movement quantity of the inclined plane in the normal direction of the inclined plane; a cavity length measuring device of the dielectric cavity for measuring the distance between the second reflection point and the conductor reflection surface is used for manufacturing a displacement sensor, the end surfaces of the shell and the inner rod conductor region of the cavity length measuring device are on the same plane, the plane is the plane where the second reflection point is located, and the plane is parallel to the conductor reflection surface, namely the axis of the cavity length measuring device is parallel to the normal of the inclined plane; the inclined plane is a conductor reflecting plane;

the inclination angle of the inclined plane is a known quantity theta, when the horizontal displacement of the displacement meter probe rod is w, the resonant frequency/resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, so that the distance variation from a second reflection point of the cavity length measuring device to the conductor reflection surface is obtained, namely the cavity length variation of the dielectric cavity is delta d which is w.sin theta; the size of the cavity length variation delta d of the dielectric cavity between the second reflecting point and the conductor reflecting surface can be determined through the variation of the resonant frequency/the cavity length of the resonant cavity, so that the size of the displacement is determined; the range of the displacement sensor is increased by decreasing the slope of the ramp with the maximum and minimum values of the cavity length of the dielectric cavity unchanged.

In one embodiment of the present application, the cavity length measuring device is applied to a displacement sensor based on a folding lever structure;

the end face of the side, with less folding number, of the folding lever is fixed with a conductor reflecting surface, so that the large displacement variation in the axial direction can be changed into the small movement of the conductor reflecting surface in the axial direction; a cavity length measuring device of the dielectric cavity for measuring the distance from the second reflection point to the conductor reflection surface is used as a displacement sensor, and a demodulating device, the cavity length measuring device of the dielectric cavity, M folding and folding fixed points, N folding and probe rods are arranged from left to right in sequence; the end surfaces of the shell of the cavity length measuring device and the inner rod conductor region are on the same plane, the plane is the plane where the second reflection point is located, the plane is parallel to the conductor reflection surface, namely the axis of the cavity length measuring device is vertical to the conductor reflection surface, and the axis of the cavity length measuring device is the same as the movement direction of the folding end surface probe rod;

the displacement is reduced by folding the lever structure; the folding lever is provided with a plurality of rotating shafts, the fixed point of the folding lever structure is close to the conductor reflecting surface, M folds are formed between the fixed point and the conductor reflecting surface, and N folds are formed between the fixed point and the displacement sensor probe; half the length of each fold between a fixed point to the displacement sensor probe is L; half the length of each fold between the fixed point to the reflective surface of the conductor is a; if the displacement of the right probe rod is w, the distance change between the second reflection point and the conductor reflection surface, i.e. the cavity length change Δ d of the dielectric cavity, is:

the cavity length variation of the open type hollow coaxial cable-Fabry-Perot resonant cavity can determine the distance variation between the second reflecting point and the conductor reflecting surface, namely the cavity length variation of the dielectric cavity is delta d, and the cavity length variation range of the dielectric cavity is limited between the second reflecting point and the conductor reflecting surface, so that the larger the measuring range of the displacement sensor is, the smaller the ratio of Na to ML is; the displacement variation is always proportional to the cavity length variation of the dielectric cavity.

In one embodiment of the present application, the cavity length measuring device is applied in a displacement sensor based on a gear and rack structure;

the gear and rack structure is composed of at least one of the following mechanical structures: the structure of the gear and the rack reduces the larger displacement variation, so that the distance between the second reflection point and the conductor reflection surface is changed in a smaller way, and the variation is delta d, namely the cavity length variation of the dielectric cavity is delta d; the displacement variation and the delta d are always in direct proportion; the end surfaces of the outer shell and the inner rod conductor region of the dielectric cavity length measuring device are on a plane, the plane is a plane where the second reflection point is located, and the plane is parallel to the conductor reflection surface, namely the axis of the cavity length measuring device is vertical to the conductor reflection surface;

the probe rod of the displacement sensor is provided with a first rack, when the displacement changes, the first rack is driven to move, the first rack is butted with a large-diameter gear on a double-layer gear, a small-diameter gear on the double-layer gear is butted with a second rack, the end surface of the second rack is fixedly provided with a conductor reflecting surface, the axis of the conductor reflecting surface is parallel to the axis of the outer shell and the inner rod of the cavity length measuring device, and the cavity length measuring device is fixed on the substrate; when the displacement of the probe rod is changed greatly, the displacement reduction is carried out through the double-layer gear, so that the second rack with the conductor reflecting surface is changed in a smaller displacement mode, namely the distance between the second reflecting point and the conductor reflecting surface is changed in a smaller mode, and the change amount is delta d; through calibration, a linear relation between the displacement variation and delta d can be obtained; if the measuring range of the displacement sensor is large, the displacement is not reduced enough by one double-layer gear, and the displacement can be reduced by combining a plurality of double-layer gears; or,

the probe rod of the displacement sensor is provided with a first rack, when the displacement changes, the first rack is driven to move, the first rack is in butt joint with a first gear with a worm, the first gear and the worm share a rotating shaft, and the first gear rotates to drive the worm to rotate; the worm is in butt joint with the second gear, and the larger displacement is reduced through the worm to drive the second gear to rotate slightly; the second gear wheel is in butt joint with a second rack, the end face of the second rack is a conductor reflecting surface, the axis of the conductor reflecting surface is parallel to the axes of the outer shell and the inner rod of the cavity length measuring device, and the cavity length measuring device is fixed on the substrate; by calibration, a linear relation between the displacement and the cavity length variation Δ d of the dielectric cavity can be obtained.

In one embodiment of the present application, the cavity length measuring device is applied to a refractive index sensor, which is a first refractive index sensor or a second refractive index sensor;

in the first refractive index sensor, the outer shell and the inner rod of the cavity length measuring device of the dielectric cavity are arranged on the left, the conductor reflecting surface is arranged on the right, the right end surface of the inner rod conductor region of each cavity length measuring device is used as a second reflecting point, and the end surface of the inner rod conductor region is not in contact with the conductor reflecting surface, or is connected by an insulator, or is connected by a conductor with the resistivity larger than or equal to a preset threshold value; the end surface of the conductor region of the shell and the end surface of the inner rod are in the same plane, or the end surface of the conductor region of the shell is positioned on the right side of the end surface of the inner rod, and the shell and the conductor reflection surface are connected by a conductor or an insulator or not; the conductor reflecting surface is arranged at the right end of the second reflecting point, the plane where the second reflecting point is arranged is parallel to the conductor reflecting surface, and the geometric distance d between the second reflecting point and the conductor reflecting surface is kept unchanged, namely the geometric cavity length d of the dielectric cavity is kept unchanged; a sealing structure is arranged between the outer shell and the inner rod at the left end of the second reflection point, so that liquid or solid or gas with the refractive index to be measured is filled between the plane where the second reflection point is located and the conductor reflection surface; the measured actual cavity length of the dielectric cavity is changed before and after the filling is put into the filling due to different refractive indexes of the filling, the cavity length d 'is related to the refractive index, so that the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the distance d' between the second reflecting point and the conductor reflecting surface can be determined according to the resonant frequency/the resonant cavity length, namely after the filling is put into the filling, the cavity length of the dielectric cavity is d ', and the refractive index of the filled liquid or solid or gas can be obtained according to the ratio of d to d'; the shell is connected with the conductor reflecting surface partially or completely, and the structure of the conductor reflecting surface at least comprises a porous structure;

in the second refractive index sensor, the shell and the inner rod are arranged on the left, the conductor reflecting surface is arranged on the right, the conductor region of the inner rod is connected with the conductor reflecting surface, the end surface of the conductor region of the shell is arranged on the left side of the end surface of the inner rod, namely on the left side of the conductor reflecting surface, and the right end surface of the conductor region of the shell of each sensor is used as a second reflecting point; the end surface of the shell conductor region is not contacted with the conductor reflecting surface, or is connected by an insulator, or is connected by a conductor with the resistivity more than or equal to a preset threshold value; the plane where the second reflection point is located is parallel to the conductor reflection surface, and the geometric distance d between the second reflection point and the conductor reflection surface is kept unchanged, namely the cavity length of the dielectric cavity is unchanged; a sealing structure is arranged between the outer shell and the inner rod in the area at the left end of the second reflection point, so that liquid or solid or gas with the refractive index to be measured is filled between the plane where the second reflection point is located and the conductor reflection surface; because the refractive indexes of the fillers are different, the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed before and after the fillers are put into the open type hollow coaxial cable-Fabry-Perot resonant cavity, the geometric cavity length d of the dielectric cavity is not changed, the measured cavity length of the dielectric cavity is d 'after the fillers are put into the open type hollow coaxial cable-Fabry-Perot resonant cavity, and the refractive index of the filled liquid or solid or gas can be obtained through the ratio of d to d'.

In one embodiment of the present application, the cavity length measuring device is used in a sensor for measuring corrosion; the sensor for measuring corrosion has the following two conditions:

the first working condition is that the conductor reflecting surface is corroded, the structure of a sensor for measuring the corrosion is the same as that of the refractive index sensor, and the distance between the second reflecting point and the conductor reflecting surface is kept unchanged, namely the geometric cavity length d of the dielectric cavity is unchanged; the dielectric cavity between the second reflecting point and the conductor reflecting surface is a cavity, and the carrier of the conductor reflecting surface is solid or made into a pore structure so as to enlarge the corrosion area and increase the sensitivity of the sensor; the material of the conductor reflecting surface is a material which can generate corrosion; the shell and the conductor reflecting surface are connected partially or in a pore structure, so that liquid or gas can be more easily immersed into the dielectric cavity; after the material of the conductor reflecting surface is corroded, a corrosion product is generated, so that the refractive index of a dielectric medium in a dielectric medium cavity between the second reflecting point and the conductor reflecting surface is changed, the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, the cavity length variation of the dielectric medium cavity can be measured through the variation of the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, the variation of the refractive index is obtained, and the corrosion degree is determined;

the second working condition is that the conductor reflecting surface is not corroded, and when the carrier of the conductor reflecting surface is not corroded, the external corrosion products can be ensured to be immersed into the dielectric cavity area between the shell and the conductor reflecting surface; the conductor reflecting surface is in a pore structure, or the shell and the conductor reflecting surface are connected by adopting a partial connection or a pore structure; when corrosion products are immersed in a dielectric cavity between the shell and the conductor reflecting surface, the refractive index of the area is changed, so that the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the variable quantity of the refractive index can be measured through the variable quantity of the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity and the size of the geometric cavity length d of the dielectric cavity, so that the corrosion degree is determined.

Drawings

FIG. 1 is a schematic diagram of a sensor according to an embodiment of the present disclosure, in which no conductor is connected between the outer casing, the inner rod, and the conductor reflection surface;

FIG. 2(a) shows the working condition that the outer shell and the inner rod are respectively communicated with the reflecting surface of the conductor by an insulator or a conductor with larger resistivity;

FIG. 2(b) is a diagram illustrating a condition where the outer shell is in conductive communication with the reflective surface of the conductor and the inner rod is in conductive communication with the reflective surface of the conductor using an insulator or a conductor having a relatively high resistivity;

FIG. 2(c) shows the condition where the inner rod is connected to the conductor reflector by the conductor and the outer shell is connected to the conductor reflector by the insulator or the conductor with higher resistivity;

FIG. 3(a) is the reflection or transmission amplitude spectrum of an open-ended hollow coax Fabry-Perot resonator according to an embodiment of the present application

FIG. 3(b) is a graph showing the relationship between the first-order resonant frequency and the cavity length (dielectric thickness) of the dielectric layer according to the embodiment of the present application;

FIG. 4(a) is a cross-sectional view of a housing in a typical use;

FIG. 4(b) is a cross-sectional view of the inner rod and the end reflector;

FIG. 5 is a cross-sectional view of a conventional reflection point;

FIG. 6 is a schematic view of the junction of the outer shell or the inner rod with the outer shell or the inner rod;

FIG. 7(a) is a schematic structural diagram of a cavity length measuring device of a reflective dielectric cavity with a coaxial cable and a demodulation main board according to an embodiment of the present application;

FIG. 7(b) is a schematic structural diagram of a cavity length measuring device of a reflective dielectric cavity with a demodulation motherboard directly connected to a sensor according to an embodiment of the present application;

FIG. 7(c) is a schematic structural diagram of a cavity length measuring device of a dielectric cavity in which a demodulation main board is directly connected to a wall of a sensor housing according to an embodiment of the present application;

FIG. 8(a) is a schematic structural diagram of a first apparatus for measuring cavity length of a transmission or positive feedback loop type dielectric cavity according to an embodiment of the present application;

FIG. 8(b) is a schematic structural diagram of a second device for measuring cavity length of a transmission or positive feedback loop type dielectric cavity according to an embodiment of the present application;

FIG. 8(c) is a schematic structural diagram of a third device for measuring cavity length of a transmission or positive feedback loop type dielectric cavity according to an embodiment of the present application;

FIG. 8(d) is a schematic structural diagram of a fourth apparatus for measuring cavity length of a transmission or positive feedback loop type dielectric cavity according to an embodiment of the present application;

fig. 9(a) is a schematic structural diagram of the working condition that the end surfaces of the outer shell and the inner rod of the embodiment of the present application are in the same cross section;

FIG. 9(b) is a schematic structural diagram of the working conditions of different cross sections of the end surfaces of the outer shell and the inner rod in the embodiment of the present application;

fig. 9(c) is a schematic diagram of the end surfaces of the outer shell and the inner rod of the embodiment of the present application with a diameter expansion structure, that is, a structural schematic diagram of the diaphragm pressure sensor and the acoustic wave sensor;

FIG. 9(d) is a schematic diagram of the end surfaces of the outer shell and the inner rod of the embodiment of the present application with a diameter expanding structure and the dielectric cavity with a medium in the cavity;

FIG. 9(e) is a schematic diagram of a conductor connected between the inner rod and the conductor reflector of the outer shell with a conductor or insulator medium between the outer shell and the conductor reflector according to the embodiment of the present application;

FIG. 10(a) is a schematic structural diagram of a C-type Bourdon tube pressure sensor in accordance with an embodiment of the present application;

FIG. 10(b) is a schematic structural diagram of a helical Bourdon tube pressure sensor in accordance with an embodiment of the present application;

fig. 11 is a schematic structural diagram of an acceleration sensor according to an embodiment of the present application;

fig. 12(a) is a schematic structural view of a first flow rate sensor according to an embodiment of the present application;

fig. 12(b) is a schematic structural view of a second flow rate sensor according to an embodiment of the present application;

fig. 12(c) is a schematic structural view of a third flow rate sensor according to an embodiment of the present application;

FIG. 13(a) is a schematic structural diagram of a first load cell in accordance with an embodiment of the present application;

FIG. 13(b) is a schematic structural diagram of a second load cell in accordance with an embodiment of the present application;

FIG. 14 is a schematic diagram of a strain gauge according to an embodiment of the present application;

FIG. 15(a) is a schematic diagram of a second horizontally disposed single direction inclinometer according to an embodiment of the present application;

FIG. 15(b) is a schematic diagram of a first horizontally disposed single direction inclinometer according to an embodiment of the present application;

FIG. 16 is a schematic diagram of a horizontally disposed bi-directional inclinometer according to an embodiment of the present application;

FIG. 17(a) is a schematic structural diagram of a second unidirectional inclinometer based on a pressure sensor according to an embodiment of the present application;

FIG. 17(b) is a schematic structural diagram of a second bi-directional pressure sensor-based inclinometer according to an embodiment of the present application;

FIG. 18(a) is a schematic structural view of an XZ slip meter according to an embodiment of the present application;

fig. 18(b) is a schematic structural view of an XYZ directional slip meter according to an embodiment of the present application;

FIG. 19(a) is a schematic structural diagram of a first displacement sensor based on a spring and a diaphragm according to an embodiment of the present application;

FIG. 19(b) is a schematic structural diagram of a second displacement sensor based on a spring and a diaphragm according to an embodiment of the present application;

fig. 20(a) is a schematic structural diagram of a displacement sensor for performing displacement reduction based on an inclined plane according to an embodiment of the present application;

fig. 20(b) is a schematic structural diagram of a displacement sensor for displacement reduction based on a folding lever structure according to an embodiment of the present application;

fig. 20(c) is a schematic structural diagram of a displacement sensor for displacement reduction based on a double-layer gear according to an embodiment of the present application;

fig. 20(d) is a schematic structural diagram of a displacement sensor for displacement reduction based on a worm according to an embodiment of the present application;

fig. 21 is a schematic structural diagram of a sensor for measuring refractive index or corrosion according to an embodiment of the present application.

Description of reference numerals:

1-a housing, which can be a hollow tube, a rod, a spring or a continuous conductor of other shape; 2-the inner rod can be hollow or solid, and can also be a spring or a continuous conductor with other shapes; 3-the first reflection point can be a conductor or an insulator, can be connected with the outer shell or the inner rod, can also be unconnected, and can be in any shape or a combination of a plurality of parts; 4-a second reflection point having the same attribute as the first reflection point; 5-a resonant cavity, the interior of which can be gas or liquid; 6-coaxial cable adapter; 7-a central signal pin of the coaxial cable adapter; 8-coaxial cable for transmission; 9-demodulation mainboard, the instrument for demodulating the frequency spectrum, which can be a vector network (vector network for short) analyzer, or a scalar microwave analyzer, or a demodulation circuit board for measuring and demodulating the frequency spectrum, does not include transmission lines such as coaxial cables for transmission; 10-a system of second reflection points, dielectric cavities and reflective surfaces; 11-a conductor reflecting surface, usually made of a conductive material, in particular a semiconductor or an insulator; 12-dielectric cavity, the inside of which can be filled with non-conductive solid, gas, liquid and other insulator materials; 13-the filler between the outer shell or the inner rod and the conductor reflecting surface can be solid, gas or liquid, can be a conductor or an insulator; 14-a terminal; 15-a carrier of reflective surfaces; 16-radio frequency coaxial cable adapter; 17-the sealing device of the end surfaces of the shell 1 and the inner rod 2 can be a conductor or an insulator; the connector can be a closed or non-closed structure, and can also be a coaxial cable adapter used as an end face; 20-Bourdon tube, can be C-type Bourdon tube, can be various Bourdon tubes such as the spiral Bourdon tube; 21-a connector to secure the bourdon tube to the housing; 22-bourdon tube mount; 23-a pressure port; 24-means for fixing the reflector carrier; 25-hinging; 26-a clamp for clamping the bourdon tube; 27-a mass block; 31-a baffle; 32-housing wall or container wall; 33-a fluid; 34-beams or thicker membranes; 35-dynamometer fixation point; 36-dynamometer load point; 37-parts attached to the housing, with lower fixing parts 38; 38-an object impacted by the fluid; 39-hinge point; 40-a hinged part connected to the second reflection point carrier; 41-a first limit piece of the strain gauge fixed with the left end shell 61; 42-a second limit piece of the strain gauge, fixed with the right end shell 62; 51-conductor extension ring of the end face of the housing; 52-a mass; 53-flexible cord or elastic rod; 54-a wire hanger (bracket); 55-mass of a bidirectional inclinometer; 56-fixing points of flexible ropes or elastic rods to the top plate and the mass block; 57-a rigid vertical rod of the cavity length measuring device for the fixed dielectric cavity, rigidly connected to the sensor and the top plate; 58-rigid top plate, or rigid body of cavity length measuring device connecting and fixing several dielectric cavities; 59-a container; 60-single pressure sensor; 61-a carrier with inclined holes for holding a cavity length measuring device of a dielectric cavity; 62-sealing means of the slip meter; 63-a carrier with an inclined surface at the lower half part of the slippage meter; 64-Medium A fixed to the slip meter carrier 61; 65-Medium B fixed to the slippage meter carrier 63; 67-first slope of the bidirectional slip meter; 68-a second slope of the bidirectional slip meter; 69-third slope of the two-way slip meter; 71-a first fixed end of the spring; 72-a spring; 73-the second fixed end of the spring, 74-the displacement sensor probe; 75-linear motion bearings; 81-inclined plane; 82-displacement sensor housing; 83-a retaining block body; 84-housing of linear motion bearing; 85-linear motion bearing; 86-sealing means, which may be parts such as sealing rubber rings; 87-fixing means for fixing the coaxial cable displacement sensor housing; 88-anti-sway slider; 89-a sealing plug on the end face of the displacement sensor; 91-fixed point of lever structure, only limit displacement, not limit rotation; 92-lever structure between the fixing point 91 and the displacement sensor transmission rod 96; 93-lever structure between the fixing point 91 and the displacement sensor probe 95; 94-the connecting hinge point between the lever structure 12 and the displacement sensor probe rod 95; 95-displacement sensor probe; 96-displacement sensor transmission rod; 100-demodulation device, which is a general name of an instrument for demodulating the cavity length of the resonant cavity, and comprises all demodulation main boards based on reflection, transmission or loop, and transmission lines such as a transmission coaxial cable and the like, wherein the sensor is connected to the demodulation main boards; 101-a single level sensor comprising a sensor body and a demodulation means; 102-a displacement sensor probe with a first rack; 103-a first rack; 104-bull gears on double layer gears; 105-pinion on double-layer gear; 106-a shaft of the double gear fixed to the base plate; 107-second rack; 108-second rack displacement sensor transmission rod; 109-a restraining device for the displacement sensor probe 102 to move only axially, fixed to the housing 1, usually a linear motion bearing, etc.; 110-a gear; 111-common axis of rotation of the gear and worm; 112-a gear coaxial with the worm; 113-worm coaxial with gear; 114-bearings constraining the rotating shaft 111; 115-a retaining block body connected with the rack and the probe rod; 116-a mounting carrier of parts such as a gear, a rack, a worm and a displacement sensor resonant cavity part.

Detailed Description

The embodiment of the application provides a novel cavity length (dielectric layer thickness) measuring device for measuring a dielectric cavity based on a microwave principle, wherein the cavity length measuring device for the dielectric cavity comprises a sensor and a demodulating device, wherein the sensor comprises an open hollow coaxial cable-Fabry-Perot resonant cavity, a first reflection point, a second reflection point, a conductor reflection surface and the dielectric cavity, and the cavity length measuring device for the dielectric cavity can measure the cavity length of the dielectric cavity and is combined with some mechanical designs to form a sensor for measuring various physical parameters. The embodiment of the application combines the cavity length measuring device of the dielectric cavity and the auxiliary mechanical design, and the cavity length measuring device can be changed into the following sensors: various sensors such as diaphragm pressure sensors, bourdon tube pressure sensors, acceleration sensors, flow rate sensors, load cells (also called dynamometers), strain gauges, inclinometers, slip sensors, displacement sensors, refractive index sensors, and corrosion sensors.

In the technical solution of the embodiment of the application, the sensor can measure parameters such as pressure, flow velocity, force, strain, inclination angle, slippage, displacement, refractive index, corrosion and the like with high precision based on different mechanical transmission modes, and the measurement principle is based on the principle of an open hollow coaxial cable-fabry-perot resonant cavity, where the sensor includes an open hollow coaxial cable-fabry-perot resonant cavity (also referred to as a resonant cavity for short), a first reflection point, a second reflection point, a conductor reflection surface and a dielectric cavity, and further includes a housing and an inner rod (optionally), where the structure of the open hollow coaxial cable-fabry-perot resonant cavity is convenient to manufacture, two reflection points (i.e. the first reflection point and the second reflection point) do not move relatively (generally, the positions of the two reflection points are fixed), by means of the movement of the reflecting surface of the conductor, namely the change of the cavity length (the thickness of the dielectric layer) of the dielectric cavity, the pressure, the flow speed, the force, the strain, the inclination angle, the refractive index and other physical quantities under the action of static force and dynamic force can be measured. The dielectric within the dielectric cavity may be a conductor or an insulator, and may be a solid, liquid, or gas. In addition, the temperature compensation of the sensor is very convenient and is not influenced by factors such as electromagnetism. The sensor designed by the embodiment of the application has the advantages of high precision, strong anti-interference capability, strong durability and the like, has wide application prospect, and is particularly suitable for measuring the mechanical property and the refractive index of the structure under the static and dynamic actions with high precision. The sensor can easily work between minus sixty degrees and hundreds of degrees due to the stable performance of the materials adopted by the sensor, and can work in a larger temperature range by replacing manufacturing materials. In summary, the sensor of the embodiment of the present application is not interfered by any electromagnetic signal, the influence of temperature on the sensor is very small, and the temperature compensation is very easy to realize.

The open type hollow coaxial cable-fabry-perot resonant cavity in the embodiment of the application is similar to a traditional optical fabry-perot resonant cavity, and is different from the optical fabry-perot resonant cavity in that the open type hollow coaxial cable-fabry-perot resonant cavity is based on a microwave principle. The microwave generates resonance in a Fabry-Perot cavity formed by two reflecting points as high reflecting points of the hollow coaxial cable, the resonance frequency spectrum is coherent with the cavity length, and under the condition that the distance between the two reflecting points is kept unchanged, the resonance frequency/the cavity length of the resonant cavity can also be influenced by the distance between a second reflecting point and a conductor reflecting surface, namely the cavity length of the dielectric cavity, wherein the second reflecting point is between the first reflecting point and the conductor reflecting surface. The open type hollow coaxial cable-Fabry-Perot resonant cavity belongs to a resonance phenomenon caused by multi-path interference, and has the characteristics of high demodulation precision, high signal-to-noise ratio, high demodulation device cost performance and the like. The dielectric cavity length can be obtained with high precision by analyzing the resonance spectrum/the cavity length. According to the embodiment of the application, different physical quantities are converted into cavity length variable quantities of the dielectric cavity through a series of mechanical structures, so that high-precision measurement of each physical quantity is completed. The sensor comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity, a first reflection point, a second reflection point, a conductor reflection surface and a dielectric cavity; the first reflection point is arranged at a first position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the second reflection point is arranged at a second position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the conductor reflection surface is arranged at a third position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, relative movement does not occur between the first reflection point and the second reflection point, the reflectivity of the first reflection point and the reflectivity of the second reflection point are greater than or equal to a preset threshold value, and the first reflection point and the second reflection point are high reflection points; a dielectric cavity is arranged between the second reflecting point and the conductor reflecting surface, and the dielectric in the dielectric cavity can be a conductor or an insulator and can be solid, liquid or gas; the conductor reflecting surface can move or deform, resulting in a change in the cavity length of the dielectric cavity.

So that the manner in which the features and elements of the present embodiments can be understood in detail, a more particular description of the embodiments, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings.

Fig. 1 is a schematic diagram of a sensor provided in an embodiment of the present application, and as shown in fig. 1, the sensor includes: the device comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity 5, a first reflection point 3, a second reflection point 4, a conductor reflection surface 11 and a dielectric cavity 12. Further, the sensor further includes: a shell 1 and an inner rod 2. The inner rod 2 and the outer shell 1 have diameters 2a and 2b, respectively. The electrostatic capacitance is excited by the tem (transverse Electric and magnetic) field of the coaxial line on the aperture. When the dielectric layer at the aperture is infinitely thick (i.e., d → ∞), the formula for calculating the fringe capacitance is as shown in formula (1):

wherein epsilon₀Is a vacuum dielectric constant of ∈_rFor the relative dielectric constant, when the thickness of the dielectric layer at the aperture is d, as shown in fig. 1, the calculation formula of the resulting additional capacitance is shown in formula (2):

therefore, the calculation formula of the total fringe capacitance of the open type hollow coaxial cable resonant cavity is shown as formula (3):

C＝C₁+C₂(3)

the calculation formula of the input reflection coefficient on the open plane is shown in formula (4):

wherein Z₀Is the characteristic impedance of a hollow coaxial cable. The calculation formula of the reflection coefficient (S11) is shown in formula (5):

δ -4 π Lf/C represents the delay of the round-trip phase, C is the speed of light in air, L is the physical length between the metal pillar (i.e., the first reflection point) and the open end (i.e., the second reflection point), f is the frequency of the electromagnetic wave propagating inside the hollow coaxial cable, Γ₁And Γ₂Is the composite reflection coefficient of two reflection points, i.e., the first reflection point and the second reflection point.

The parameters of the open type hollow coaxial cable-fabry-perot resonator are substituted into equation (5), and the obtained reflection spectrum is shown in fig. 3(a), wherein the first-order resonance frequency is mainly researched, and the second-order and third-order resonance frequencies can also be researched.

The distance d is adjusted and the corresponding first order resonant frequency is tracked. The relationship between the first order resonance frequency and the cavity length of the dielectric cavity (thickness of the dielectric layer), i.e., the distance between the second reflection point and the conductor reflection surface, is shown in fig. 3 (b). The medium inside the dielectric cavity (dielectric layer) was air in the simulation. The basic idea of making a sensor using an open core coaxial cable-fabry-perot resonator is based on the fact that the cavity length (thickness of the dielectric layer) of the dielectric cavity can be accurately calculated from the reflection amplitude spectrum or the transmission amplitude spectrum.

The cavity length measuring apparatus for measuring a dielectric cavity using the microwave principle according to the embodiments of the present application will be described in detail below with reference to specific configurations, and the cavity length measuring apparatus according to the embodiments of the present application includes: a sensor and a demodulation device. In all embodiments of the present application:

1) the outer shell 1 or the inner rod 2 may be a conductor part, or may be a combined component formed by connecting a plurality of conductor parts together (to ensure the conductivity of the connection), and thus, the outer shell 1 or the inner rod 2 is a continuous conductor respectively. One conductor part shown in all the drawings does not necessarily represent a simple conductor part, but may represent a composite conductor part in which a plurality of conductor parts are combined by different connection means.

2) Regarding the movement of the conductor reflecting surface:

the sensor comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity 5, a first reflection point 3, a second reflection point 4, a dielectric cavity 12 and a conductor reflection surface 11, wherein the first reflection point 3 is arranged at a first position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the second reflection point 4 is arranged at a second position inside the resonant cavity, and the first position and the second position are fixed; the reflectivity of the first reflection point 3 and the second reflection point 4 is greater than or equal to a preset threshold value; a dielectric cavity 12 (dielectric layer) is arranged between the conductor reflecting surface 11 and the second reflecting point 4, the distance between the second reflecting point 4 and the conductor reflecting surface 11 can be changed, namely the cavity length of the dielectric cavity can be changed, and the change mode can be realized by the movement or deformation of the conductor reflecting surface; the cavity length change of the dielectric cavity can change the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, and the cavity length change quantity of the dielectric cavity can be determined by the resonant frequency/the resonant cavity length change quantity; the demodulation device is connected with the sensor and used for analyzing microwave signals in the sensor to obtain the resonant frequency/resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity. Such a structure can be used for various types of sensors mentioned in the embodiments of the present application.

3) With regard to the demodulation main board of the demodulation device in the sensor:

the demodulation main board 9 of the sensor consists of a high-performance processor, a microwave transmitting module and a microwave receiving module; the device can be a vector network (vector network for short) analyzer, a scalar microwave analyzer, or a demodulation circuit board for measuring and demodulating frequency spectrum, and does not comprise a transmission line such as a coaxial cable for transmission. The demodulation main board 9 demodulates the resonance frequency spectrum to obtain the resonance frequency/the resonance cavity length of the open type hollow coaxial cable-fabry-perot resonance cavity in the sensor, and further obtains the cavity length of the dielectric cavity. The demodulation device 100 is a generic term for a device for demodulating the cavity length of the resonant cavity, and includes all transmission lines such as a demodulation motherboard 9 based on reflection, transmission, or loop, a radio frequency coaxial cable adapter, and a transmission coaxial cable 8 for connecting the sensor to the demodulation motherboard, and when each sensor is specifically described, the demodulation device 100 is used to represent all types of demodulation motherboards and all connection methods between the sensor and the demodulation motherboard.

4) Regarding the resonance mode of the sensor:

the sensor described in all embodiments of the present application has both reflective and transmissive connections, and the transmissive cavity length measuring device has at least the following modes: positive feedback loop mode, loop-free mode. Further, there may be two reflection points, or one reflection point, or no reflection point in the positive feedback loop. When the positive feedback loop has two reflection points, the radio frequency coaxial cable adapter is usually connected to the shell between the two reflection points, the demodulation main board is used for measuring the cavity length of the resonant cavity between the two reflection points, and the cavity length is influenced by the cavity length of the dielectric medium; when there is only one reflection point, the rf coax transition used to connect the waveform amplifier is typically connected to the housing between the reflection point and the rf coax transition. When the positive feedback loop has no reflection point, the radio frequency coaxial cable adapter used for connecting the waveform amplifier is usually connected to the shell between the radio frequency coaxial cable adapter and the other end face of the sensor, and the demodulation main board is used for measuring the perimeter of the positive feedback loop. The structure can be applied to various sensors such as a diaphragm pressure sensor, a bourdon tube pressure sensor, an acceleration sensor, a flow velocity sensor, a force measuring sensor (also called a dynamometer), a strain gauge, an inclinometer, a slip sensor, a displacement sensor, a refractive index sensor, a gas adsorption sensor, a corrosion sensor and the like which are set forth in the application.

In the following embodiments of the present application, the reflective connection is mostly used as an example, and actually, the protection range of each sensor has the reflective and transmissive connection described above, and the transmissive cavity length measuring device includes a positive feedback loop mode and a loop-free mode, where the positive feedback loop includes three conditions of two reflection points, one reflection point and no reflection point.

All embodiments of the application also include two working conditions of an inner rod and no inner rod, and the following embodiments are exemplified by the working conditions of the inner rod.

The first embodiment is as follows: cavity length measuring device for measuring dielectric cavity by microwave principle

The cavity length measuring device of the dielectric cavity comprises: a sensor, a demodulation device; the sensor part comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity 5, a first reflection point 3, a second reflection point 4, a dielectric cavity 12 and a conductor reflection surface 11; the demodulation device part comprises a demodulation main board 9 and optionally further comprises a transmission line such as a coaxial cable; wherein the first reflection point 3 is arranged at a first position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the second reflection point 4 is arranged at a second position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, and the first position and the second position are fixed; the reflectivity of the first reflection point 3 and the second reflection point 4 is greater than or equal to a preset threshold value; the first reflection point 3 is close to the demodulation main board 9, and a dielectric cavity 12 is arranged between the conductor reflection surface 11 and the second reflection point 4; the demodulation main board 9 is connected to the sensor, and configured to analyze a microwave signal in the sensor to obtain a resonant frequency/a resonant cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity in the sensor, where the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity in the sensor is a distance between the first reflection point and the second reflection point, and the cavity length is affected by a cavity length of the dielectric cavity 12, that is, by a thickness of the dielectric layer.

The cavity length measuring device of the dielectric cavity in the present embodiment is classified into the following three types:

1) a reflective cavity length measuring device, in which:

When the sensor comprises a shell and an inner rod, one end of the shell and one end of the inner rod are both connected with the radio-frequency coaxial cable adapter, and the radio-frequency coaxial cable adapter is connected with the demodulation mainboard through a coaxial cable; or the shell and the first end of the inner rod are directly connected with the demodulation mainboard, namely the shell and the first end of the inner rod can be connected with the demodulation mainboard through a first radio frequency coaxial cable adapter and can also be directly connected with the demodulation mainboard. At least one part of the first reflection point and the second reflection point is arranged in the envelope range of the shell and the inner rod;

when the sensor only has a shell and does not have an inner rod, one end of the shell is connected with the radio frequency coaxial cable adapter, and the radio frequency coaxial cable adapter is connected with the demodulation main board through a coaxial cable; or the first end of the shell is directly connected with the demodulation mainboard, namely the first end of the shell can be connected with the demodulation mainboard through the first radio frequency coaxial cable adapter, and also can be directly connected with the demodulation mainboard. The first reflection point and the second reflection point are disposed within an envelope of the housing.

Wherein, the demodulation mainboard is: a vector network analyzer, or a microwave generating source plus a scalar network analyzer, or a microwave time domain reflectometer, or a demodulation circuit board; the other end of the sensor is of an open structure or a sealed structure, the end surfaces of the outer shell and the inner rod face the conductor reflecting surface, and a dielectric cavity is arranged between the second reflecting point and the conductor reflecting surface.

2) A transmissive cavity length measuring device, in which:

The cavity length measuring device has at least the following modes: a positive feedback loop mode, a loop-free mode; wherein,

in the positive feedback loop mode, the demodulation main board includes: directional coupler, waveform amplifier, frequency counter/frequency spectrograph, these components and parts have multiple connected modes. For example, the first radio frequency coaxial cable adapter is connected to the directional coupler, the waveform amplifier and the second radio frequency coaxial cable adapter are sequentially connected, and the frequency counter/frequency spectrograph is connected to the directional coupler;

in the loop-free mode, the demodulation main board is a vector network analyzer, a scalar microwave analyzer or a demodulation circuit board.

Further, the positive feedback loop mode includes: a microwave positive feedback loop and a positive feedback loop based on a photoelectric oscillator; wherein,

in the microwave positive feedback loop, comprising: the device comprises a coaxial cable loop, a microwave directional coupler, a microwave amplifier or a microwave power separator and a frequency counter/frequency spectrograph, wherein all devices in the demodulation main board are connected through the coaxial cable loop or a circuit board with a loop;

in the optoelectronic oscillator based positive feedback loop, comprising: the device comprises a high-speed photoelectric demodulator, a laser or light emitting diode light source, an optical fiber loop, an optical fiber coupler, a microwave amplifier or an optical amplifier, a microwave directional coupler or a microwave power splitter and a frequency counter/frequency spectrograph, wherein all devices in the demodulation main board are connected through the optical fiber loop.

Structurally, when the sensor comprises an outer shell and an inner rod, the first ends of the outer shell and the inner rod are connected with a first radio-frequency coaxial cable adapter, and the first radio-frequency coaxial cable adapter is connected to a demodulation main board through a first coaxial cable; or the shell and the first end of the inner rod are not connected with the demodulation mainboard through coaxial cables, namely the first ends of the shell and the inner rod can be connected with the demodulation mainboard through a first radio frequency coaxial cable adapter and can also be directly connected with the demodulation mainboard. The shell wall is connected with a second radio frequency coaxial cable adapter, and the second radio frequency coaxial cable adapter is connected to the demodulation main board through a second coaxial cable; or the shell wall is not connected with the demodulation mainboard through a coaxial cable, namely the shell wall can be connected with the demodulation mainboard through a second radio frequency coaxial cable adapter, and can also be directly connected with the demodulation mainboard. At least one part of the first reflection point and the second reflection point is arranged in the envelope range of the shell and the inner rod;

when the sensor is only provided with the shell and does not have the inner rod, the first end of the shell is connected with a first radio frequency coaxial cable adapter, and the first radio frequency coaxial cable adapter is connected to the demodulation main board through a first coaxial cable; or the first end of shell all is not connected with demodulation mainboard through coaxial cable, and the first end of shell can be through first radio frequency coaxial cable adapter connection demodulation mainboard promptly, also can the lug connection demodulation mainboard. The shell wall is connected with a second radio frequency coaxial cable adapter, and the second radio frequency coaxial cable adapter is connected to the demodulation main board through a second coaxial cable; or the shell wall is not connected with the demodulation mainboard through a coaxial cable, namely the shell wall can be connected with the demodulation mainboard through a second radio frequency coaxial cable adapter, and can also be directly connected with the demodulation mainboard. At least a portion of the first reflection point and the second reflection point are disposed within an envelope of the housing.

In this embodiment, the numbers of the core devices are as follows: the device comprises a shell 1, an inner rod 2, a first reflection point 3, a second reflection point 4, an open type hollow coaxial cable-Fabry-Perot resonant cavity 5, a conductor reflection surface 11, a dielectric cavity 12, a vector network analyzer or a scalar microwave analyzer or a demodulation circuit board and other demodulation main boards 9, wherein:

the shell 1 is a continuous conductor connected to the outer ring of the radio frequency coaxial cable adapter, and the conductor may be a tube, a semicircular tube, a spring, a rod, or a combined conductor formed by connecting a plurality of conductors through a conductive connecting piece. For example: two or more nested conductor tubes, two or more conductor tubes communicating by a metal connection, etc. Fig. 4(a) illustrates a cross-sectional view of a typical case. Fig. 6 illustrates a common connection mode between different sections of the housing when the housing is formed by a plurality of parts.

The inner rod 2 is also a continuous conductor, and as with the outer shell 1, the inner rod 2 can also be in different geometric shapes, the cross section can be in a circular, rectangular or semicircular shape, and the like, can be a straight rod, can be a curved rod such as a spring, and the like, and can also be a connecting piece for connecting a plurality of conductors together. Under special conditions, the cavity length measuring device can still measure required parameters by demodulating signals through a demodulation main board without using an inner rod. Fig. 4(b) shows a cross-sectional view of a conventional inner rod. Fig. 6 illustrates a common connection mode between inner rods of different sections when the inner rods are formed by a plurality of parts.

The first reflection point 3 refers to objects within the envelope of the outer shell and the inner rod, and may be in various shapes, different sizes, conductors or insulators made of different materials, or a combination of multiple parts. As long as it can perform a reflecting function. If the reflecting point is a conductor connecting the outer envelope and the inner rod, the reflectivity of this point will be high, and if the reflecting point is not a conductor connecting the outer envelope and the inner rod, the reflectivity will be lower. Preferably, the first reflection point is a cross section with a size smaller than a preset area, and can be at least placed in a direction perpendicular to the axis of the inner rod of the sensor through one or more round rods or square rods, or a porous structure with a certain transmittance is fixed between the outer shell and the inner rod, and the area of the area, covered by the first reflection point, between the outer shell and the inner rod is smaller than the envelope area between the outer shell and the inner rod; the first reflection point forms a short circuit between the outer shell and the inner rod, or the resistance of a connecting piece between the outer shell and the inner rod is larger than or equal to a preset threshold value. The reflectivity can also be adjusted by changing the shape and the size of the section of the inner rod, a first reflection point added between the outer shell and the inner rod can be removed, and the joint of the radio frequency coaxial cable adapter and the outer shell as well as the inner rod is used as the first reflection point; when the radio frequency coaxial cable adapter and the joint of the outer shell and the inner rod are used as first reflection points, the ratio of the diameter of the inner rod to the inner diameter of the outer shell is between 0 and 1.

Fig. 5 is a cross-sectional view showing a typical reflection point, and the shaded portion is the reflection point. The first reflection point is a fixed point.

The second reflection point 4 is an end face of the outer shell, or an end face of the inner rod, or end faces of conductor regions of the outer shell and the inner rod, when the section of the end face of the outer shell or the inner rod is on a plane and the end face is at a certain distance from the conductor reflection surface, or the outer shell or the inner rod is in short circuit connection with the conductor reflection surface and the end face of the other element is at a certain distance from the conductor reflection surface, the second reflection point 4 is the end face plane of the element of which the outer shell or the inner rod is at a certain distance from the conductor reflection surface; when the section of the end face of the outer shell or the inner rod is not on the same plane and the outer shell and the inner rod are not in short circuit connection with the conductor reflecting surface, the second reflecting point 4 is a point between the planes of the end faces of the outer shell and the inner rod. The second reflection point is a fixed point.

The open type hollow coaxial cable-Fabry-Perot resonant cavity 5 refers to a resonant cavity between a first reflection point and a second reflection point and between an outer shell and an inner rod, and a medium in the resonant cavity is vacuum, gas, liquid or solid.

The conductor reflecting surface 11 is a cylinder which keeps a certain distance from the end surface of the outer shell or the inner rod and ensures that the envelope surfaces of the outer shell and the inner rod are swept along the axial direction and have a certain intersection with the area where the conductor reflecting surface is located. At least one of the outer shell 1 and the inner rod 2 is not short-circuited with the conductor reflection surface 11. The conductor reflecting surface 11 can be a single conductor, the conductor can be provided with holes and can be in various shapes; or may be a plurality of unconnected conductors or a plurality of conductors connected using an insulator.

The dielectric cavity 12 is a dielectric layer, and is a region between the second reflection point 4 and the conductor reflection surface 11, and may be filled with insulating gas, liquid or solid. By measuring the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, the cavity length of the dielectric cavity and the variable quantity thereof can be determined.

The vector network analyzer or scalar microwave analyzer or demodulation circuit board 9 is a device for measuring the reflection amplitude spectrum or transmission amplitude spectrum of the open type hollow coaxial cable-Fabry-Perot resonant cavity.

Fig. 1 illustrates core elements in a sensor provided by an embodiment of the present application, which include an outer shell 1, an inner rod 2, a first reflection point 3, a second reflection point 4, a conductor reflection surface 11, a dielectric cavity 12, and an open hollow coaxial cable-fabry-perot resonator 5. The first reflection point 3 is arranged at a first position inside the open type hollow coaxial cable-fabry-perot resonant cavity, the second reflection point 4 is arranged at a second position inside the open type hollow coaxial cable-fabry-perot resonant cavity, the conductor reflection surface 11 is arranged at a third position inside the open type hollow coaxial cable-fabry-perot resonant cavity, the first reflection point 3 and the second reflection point 4 are fixed, and the conductor reflection surface 11 can move, so that the cavity length of the dielectric cavity is changed, and the resonance frequency/the cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity is influenced.

FIG. 2(a) shows the working condition that the outer shell 1 and the inner rod 2 are respectively communicated with the conductor reflecting surface 11 by an insulator or a conductor with larger resistivity; in this case, insulating or conductive solids, liquids or gases can be filled between the conductor region of the rod in the housing and the conductor reflector 11. And 13 denotes a dielectric.

FIG. 2(b) shows a condition that the outer shell 1 is in conductive communication with the conductive reflecting surface 11, and the inner rod 2 is in conductive communication with the conductive reflecting surface 11 by using an insulator or a conductor having a resistivity greater than or equal to a predetermined threshold; in this case, a solid, liquid or gas can be filled between the conductor region of the inner rod and the conductor reflection surface 11. 13 denotes an insulator or a conductor having a resistivity equal to or higher than a preset threshold.

FIG. 2(c) shows a condition that the inner rod 2 and the conductor reflecting surface 11 are connected by a conductor, and the outer shell 1 and the conductor reflecting surface 11 are connected by an insulator or a conductor with resistivity greater than or equal to a preset threshold; the space between the conductor area of the housing and the conductor reflection surface 11 can be filled with an insulating solid, liquid or gas. 13 denotes an insulator or a conductor having a resistivity equal to or higher than a preset threshold.

Fig. 3(a) is a reflection or transmission amplitude spectrum of an open type hollow coaxial cable-fabry-perot resonator when the cavity length of a dielectric cavity is measured by the microwave principle. The first-order resonant frequency, namely the peak corresponding to the low frequency, is mainly researched, and the resonant frequencies of the second order, the third order and the like can also be researched.

Fig. 3(b) is a graph of the relationship between the first-order resonance frequency f and the dielectric cavity length d (dielectric layer thickness), i.e., the distance between the metal plate and the open end of the coaxial cable. It can be seen that the smaller the cavity length of the dielectric cavity, the faster the resonant frequency changes and the more sensitive the sensor.

Fig. 4(a) shows a cross-section of a conventional housing 1, which may be a ring, a square frame or various irregular shapes, and may even be a spring or a round rod. Or may be divided into a combination in which a plurality of conductors are connected together as long as a continuous conductor is satisfied.

Fig. 4(b) shows a cross-sectional view of a common inner rod 2 or a conductor reflecting surface 11, wherein the inner rod can be hollow or solid, the cross-section can be various types, and the common cross-section can be circular, rectangular or regular polygon. The inner rod 2 can be a space curve structure such as a spring. The inner rod 2 may also be divided into a combination of a plurality of conductors connected together as long as a continuous conductor is satisfied. The size of the conductor reflecting surface is generally equal to or larger than that of the shell, and the projection of the shell enveloping area on the conductor reflecting surface is generally in the area of the conductor reflecting surface.

Fig. 5 is a cross-sectional view of a conventional reflection point 3, which may have various shapes. The reflecting point can be a conductor or an insulator, so long as a part of the reflecting point is within the envelope range of the outer shell 1 and the inner rod 2; the reflection point may or may not be in contact with the outer shell and/or the inner rod. Taking the case that the commonly used outer shell 1 is a cylinder and the inner rod is a round rod as an example, the reflection point may be a cylinder or a circular ring filled between the outer shell 1 and the inner rod 2, or an object covering the cavity between the outer shell 1 and the inner rod 2, such as a small round rod or a porous disk shown in fig. 3, 4 and 5 in fig. 6.

Fig. 6 is a schematic diagram of the connection between the outer shell and the outer shell or the connection between the inner rod and the outer shell after the outer shell 1 or the inner rod 2 is connected in a segmented manner. Fig. 7 shows that the common connection modes include overlapping, dislocating, nesting, or connecting by a rotating shaft, and connecting by a conductor corrugated pipe, and in short, when the different sections of the segmented outer shell 1 or inner rod 2 relatively move or rotate, the conductive continuity of the outer shell 1 or inner rod 2 is satisfied.

Fig. 7(a) to 7(c) are schematic structural views of a cavity length measuring apparatus of a reflective dielectric cavity according to an embodiment of the present application. The demodulation main board 9 may be a vector network analyzer, a scalar microwave analyzer, a demodulation circuit board, or other components.

Fig. 7(a) is a schematic structural view of a cavity length measuring apparatus of a dielectric cavity with a coaxial cable and a demodulation main board. The sensor in the cavity length measuring device comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity (resonant cavity for short) 5, a first reflection point 3, a second reflection point 4, a dielectric cavity 12 and a conductor reflecting surface 11. The first reflection point 3 is arranged at a first position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the second reflection point 4 is arranged at a second position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the conductor reflection surface 11 is arranged at a third position inside the open type hollow coaxial cable-Fabry-Perot resonant cavity, the first reflection point 3 and the second reflection point 4 are fixed and do not move relatively, and the conductor reflection surface 11 can move relative to the second reflection point 4; the reflectivity of the first reflection point 3 and the second reflection point 4 is greater than or equal to a preset threshold value. The demodulation main board 9 is connected to the sensor, and is configured to analyze a microwave signal in the sensor to obtain a cavity length of the sensor, where the cavity length of the sensor is a distance between the first reflection point 3 and the second reflection point 4, and the distance is affected by a change in a distance between the second reflection point 4 and the conductor reflection surface 11. When the distance between the first reflection point 3 and the second reflection point 4 is constant and the distance between the second reflection point 4 and the conductor reflection surface 11 is changed, the resonance frequency/the cavity length of the resonance cavity is changed, and the relation between the cavity length of the dielectric cavity (the thickness of the dielectric layer) of the first order resonance frequency (i.e., the distance between the second reflection point and the conductor reflection surface) is as shown in fig. 3(b), thereby determining the distance between the second reflection point 4 and the conductor reflection surface 11.

Fig. 7(b) is a schematic structural diagram of a cavity length measuring device of a reflective dielectric cavity with a demodulation motherboard directly connected to a sensor according to an embodiment of the present application. Directly put demodulation mainboard 9 at the terminal surface of sensor, need not coaxial cable between demodulation mainboard and the sensor and be connected, the sensor can be through first radio frequency coaxial cable adapter connection demodulation mainboard promptly, also can the lug connection demodulation mainboard. The demodulation circuit 9 is used to obtain the resonant frequency/the resonant cavity length, and other equipment can be connected through the wiring terminal 14 to transmit data.

Fig. 7(c) is a schematic structural diagram of a cavity length measuring device of a dielectric cavity in which a demodulation main board is directly connected to a wall of a sensor housing according to an embodiment of the present application. One end of the sensor is provided with a sealing device 17 on the end surfaces of the shell 1 and the inner rod 2, and the sealing device 17 can be a conductor, an insulator, a closed or non-closed structure, or a coaxial cable adapter as an end surface. The other end of the sensor is a second reflection point 4, a dielectric cavity 12 and a conductor reflection surface 11. The demodulation mainboard 9 is directly connected to the shell wall, and as for the connection method, the demodulation mainboard 9 and the shell wall can be connected through a coaxial radio frequency adapter 16, the end face of the coaxial radio frequency adapter 16 is inserted into the shell, and the end face of the adapter in the shell can be connected with a conductor extension rod so as to increase the length of a conductor inserted into the shell; it is also possible to connect the housing wall of the sensor directly to the demodulation main board. The demodulation main board 9 and the sensor are not connected by a coaxial cable 8, and the resonant frequency/the resonant cavity length can be obtained by using the demodulation main board 9.

Fig. 8(a) to 8(d) are schematic structural views of a cavity length measuring apparatus of a dielectric cavity based on a transmission or positive feedback loop. In the cavity length measuring device of the dielectric cavity based on the transmission or positive feedback loop, a sensor in the cavity length measuring device comprises an open type hollow coaxial cable-Fabry-Perot resonant cavity (resonant cavity for short), a first reflection point 3, a second reflection point 4, a dielectric cavity 12 and a conductor reflection surface 11, the sensor part and the reflection type structure are the same, and the difference lies in that the connection mode of the demodulation part is different. Specifically, the radio frequency coaxial cable adapter 6 is connected to the housing 1 and the inner rod 2 at the left ends of the housing 1 and the inner rod 2, and the other radio frequency coaxial cable adapter 16 is connected to the wall of the housing instead of the right end face. When the inner rod 2 is not provided, it is the rf coaxial cable adapter 6 that is connected to the housing 1 at the left end of the housing 1, and the other rf coaxial cable adapter 16 is connected to the wall of the housing, not the right end face. When there are two

reflection points

3 and 4, the cavity length of the resonant cavity between the two reflection points is measured, which is influenced by the distance between the second reflection point 4 and the conductor reflection surface 11, i.e. by the dielectric cavity length. When there is only one reflection point 4, the loop circumference is measured.

Fig. 8(a) is a schematic diagram of a loop structure of a first device for measuring the cavity length of a transmission or positive feedback loop type dielectric cavity, wherein a demodulation main board 9 is connected to a left-end coaxial cable adapter 6 and a radio-frequency coaxial cable adapter 16 on the wall of the shell through two coaxial cables 8; fig. 8(b) is a schematic diagram of a loop structure of a second transmission or positive feedback loop type dielectric cavity length measuring device, in which one end of a demodulation main board 9 is connected to a radio frequency coaxial cable adapter 16 connected to the wall of the housing shell, and the other end is connected to a left end coaxial cable adapter 6 by a coaxial cable 8; fig. 8(c) is a schematic diagram of a loop structure of a third device for measuring the cavity length of a transmission or positive feedback loop type dielectric cavity, in which a demodulation main board 9 is connected at one end to the end faces of the housing 1 and the inner rod 2, and at the other end to a coaxial cable adapter 16 on the housing wall through a coaxial cable 8; fig. 8(d) is a schematic diagram of a loop structure of a fourth type of cavity length measuring device for a transmission or positive feedback loop type dielectric cavity, in which one end of the demodulation main board 9 is connected to the end faces of the housing 1 and the inner rod 2, and the other end is connected to a radio frequency coaxial cable adapter 16 connected to the wall of the housing shell. Functionally, the four structures shown in fig. 8(a) to 8(d) are functionally identical. When the demodulation main board 9 is connected to the end portion of the sensor or the housing wall, the demodulation main board may be connected through a radio frequency coaxial cable adapter, or may be directly connected.

The demodulation principles of the various sensors described later in this application, either of the reflective, transmissive or positive feedback loop type, are replaced with a demodulation apparatus 100, with emphasis on the design of the mechanical structure.

Fig. 9(a) is a schematic structural diagram of the working condition in which the end surfaces of the outer shell and the inner rod of the embodiment of the present application are of the same cross section. The inner rod 2 and the conductor reflecting surface 11 do not contact each other. At this time, the second reflection point 4 is the end surface of the inner rod 2 regardless of whether a conductor or an insulator is filled between the outer shell 1 and the conductor reflection surface 11. On the contrary, if the housing 1 and the conductor reflecting surface 11 are not in contact. At this time, the second reflection point 4 is an end face of the housing 1 regardless of whether a conductor or an insulator is filled between the inner rod 2 and the conductor reflection surface 11.

Fig. 9(b) is a schematic structural diagram of the conductor region end surfaces of the outer shell and the inner rod 2 in the embodiment of the present application, which are different cross-sectional conditions, at this time, the outer shell 1, the inner rod 2, and the conductor reflection surface 11 are not in contact with each other or connected by an insulator, or connected by an insulator and then connected by a conductor, in short, the conductor region of the rod connection end surface demodulation apparatus 100 in the outer shell is not in contact with the conductor reflection surface 11. The second reflection point 4 is between the end surface of the outer shell 1 and the end surface of the inner rod 2 when the end surfaces of the outer shell 1 and the inner rod 2 are connected with the conductor reflection surface 11 in a non-contact manner or by using an insulator.

Fig. 9(c) is a schematic view of the end surfaces of the outer shell 1 and the inner rod 2 with the diameter-expanded structure according to the embodiment of the present application. The diameter of the conductor reflecting surface 11 can be enlarged by expanding, namely, the structural schematic diagram of the sensor based on the change of the diaphragm deflection, such as a high-sensitivity diaphragm type pressure sensor, an acoustic wave sensor and the like. One end of the outer shell and one end of the inner rod are connected with the demodulating device 100; the other end of the shell is connected with a diaphragm 15, the connecting material can be a conductor or an insulator, as long as one side of the conductor reflecting surface 11 of the diaphragm is provided with the conductor; the first reflection point 3 is fixed between the end surfaces 4 of the outer shell and the inner rod and the demodulation device 100, the second reflection point 4 is the end surface of the outer shell 1 or the inner rod 2, and both the two reflection points are fixed points; the first side surface of the membrane 15 close to the shell 1 and the inner rod 2 is a conductor reflecting surface 11; the end face of the inner rod 2 is connected without a conductor to the first side of the membrane 15 at a small distance. The other side of the diaphragm 15, i.e. the second side, is a pressed side, and the diaphragm is spaced from the end face of the inner rod by a certain distance and is in a non-contact state or filled with an insulator, and the diaphragm is a conductor. The principle is that when the pressure changes, the cavity length of the dielectric cavity between the second reflection point 4 and the first side 11 of the diaphragm also changes, so that the resonant frequency/the cavity length of the resonant cavity is changed, and the pressure is determined by the change of the cavity length of the resonant cavity.

Fig. 9(d) is a schematic diagram of the end surfaces of the outer shell and the inner rod of the embodiment of the present application with a diameter expanding structure and the dielectric cavity 12 with a medium in the cavity; the whole structure and the meaning of fig. 9(c) are that only the dielectric cavity 12 between the end surface of the rod 2 and the diaphragm in the housing 1 is filled with a medium, and when the distance between the end surface of the rod and the first side surface of the diaphragm in the housing is not changed, the cavity length of the dielectric cavity is affected by changing the refractive index of the medium, so that the resonant frequency/the cavity length of the resonant cavity is affected. Therefore, the method can be used for manufacturing sensors for measuring parameters such as refractive index and corrosion.

FIG. 9(e) is a schematic diagram of the inner rod, the shell and the conductor reflector plate of the embodiment of the present application with the conductor or the insulator medium between the shell and the conductor reflector plate; when the end surfaces of the outer shell and the inner rod are a cross section, the outer shell, the inner rod and the conductor reflecting surface 11 are not in contact or an insulator is arranged in the middle, and the second reflecting points 4 are the end surfaces of the outer shell 1. When the inner rod 2 and the conductor reflecting surface 11 are not in contact or an insulator is arranged in the middle, the second reflecting point 4 is the end surface of the inner rod 2 no matter whether a conductor or an insulator is filled between the shell 1 and the conductor reflecting surface 11. When the outer shell 1 and the conductor reflecting surface 11 are not in contact or an insulator is arranged in the middle, the second reflecting point 4 is the end surface of the outer shell 1 no matter whether the conductor or the insulator is filled in the dielectric cavity 12 between the inner rod 2 and the conductor reflecting surface 11.

The second implementation: pressure sensor

The pressure sensor comprises the dielectric cavity length measuring device in the first embodiment, wherein the resonant frequency/resonant cavity length variation of the sensor represents the displacement of the conductor reflecting surface relative to the second reflecting point, namely the cavity length variation of the dielectric cavity, and the cavity length variation represents the pressure.

1) First pressure sensor based on diaphragm

As shown in fig. 9(a) and 9(c), in the first pressure sensor based on the deflection change of the diaphragm 15, the main bodies of the outer shell 1 and the inner rod 2 are conductors, and one ends of the outer shell 1 and the inner rod 2 are connected with the demodulating device 100; the other end of the shell is connected with a diaphragm 15, and the connecting material between the shell and the diaphragm can be a conductor or an insulator; the first reflection point 3 is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device 100, namely at a first position; the second reflection point 4 is the end surface of the outer shell 1 or the inner rod 2, namely the second position, and the first reflection point and the second reflection point are fixed points; in general, the end surface planes of the conductor regions of the rod in the housing are on the same plane, which is a second reflection point, and an insulating material is arranged between the end surface of the housing 1 and the conductor reflection surface 11 as a support; or the conductor area of the outer shell 1 is directly connected with the conductor reflecting surface 11, a certain distance is reserved between the end surface plane of the inner rod 2 and the conductor reflecting surface 11, namely the outer shell 1 is longer than the inner rod 2, the second reflecting point 4 is the end surface plane of the inner rod 2, in a word, the outer ring of the diaphragm is fixed on the end surface of the outer shell, the middle area of the diaphragm is not contacted with the inner rod, and the deflection can be changed after the diaphragm is pressed. The first side of the diaphragm 15 close to the outer shell and the inner rod is the conductor reflecting surface 11, namely, the third position; the inner rod end face 4 is not in contact with the first side face (conductor reflection face) of the diaphragm, or is connected with an insulator, or is connected with a conductor with the resistivity larger than or equal to a preset threshold value, a common non-contact structure is adopted, namely a small distance is reserved between the inner rod end face 4 and the first side face (conductor reflection face) of the diaphragm, and a space between the end face of the inner rod 2 and the conductor reflection face 11 is a dielectric cavity 12. The first side of the diaphragm, the left side, in the figure is the conductor reflecting surface 11; the second side, the right side, is the side that is under pressure. The axis of the inner rod of the shell is vertical to the conductor reflecting surface 11, and the end surface of the inner rod 2 is parallel to the conductor reflecting surface 11 and has a certain distance with the conductor reflecting surface. The principle is that when the pressure intensity changes, the deflection of the diaphragm changes, the distance between the second reflection point 4 and the first side surface 11 of the diaphragm also changes, namely the cavity length of the dielectric cavity changes, so that the resonant frequency/the cavity length of the resonant cavity changes, and the cavity length variation of the dielectric cavity is determined through the resonant frequency/the cavity length variation of the open hollow coaxial cable-Fabry-Perot resonant cavity, so that the pressure intensity is determined. After deformation of the diaphragm 15, the first side/conductive reflective surface 11 changes from generally planar to curved, so that the changed deflection is also affected by the combined deflection of the diaphragm at various points, between a minimum deflection and a maximum deflection.

Based on the sensor of the displacement and deflection of the diaphragm 15, when the thickness of the diaphragm is larger, the end surface planes of the outer shell and the inner rod are on the same plane, and the plane is the second reflection point 4. An elastic gasket 13 with lower rigidity is arranged at the joint of the shell 1 and the diaphragm 15, the elastic gasket 13 is compressed by pressure, and the distance from the diaphragm 15 to the end face of the inner rod 4 is changed together with the deflection change of the diaphragm 15, so that the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed.

In order to increase the sensitivity of the pressure sensor, several methods may be used, one of them being to reduce the initial distance between the first side/conductor reflecting surface 11 of the diaphragm 15 and the second reflecting point 4, i.e. to reduce the initial length of the dielectric cavity 12; secondly, the thickness of the diaphragm is changed, the sensitivity can be increased by reducing the thickness of the diaphragm, and the sensitivity can be reduced by increasing the thickness of the diaphragm; thirdly, the diameter of the diaphragm is increased, the inner diameter and the outer diameter of the end face of the shell 1 are increased, the outer ring of the end face of the diameter-expanding structure is connected with the diaphragm with the diameter larger than or equal to the diameter of the shell, and the outer ring of the diaphragm is hermetically connected with the end face of the diameter-expanding structure, as shown in fig. 9 (c).

2) Second pressure sensor based on Bourdon tube

As shown in fig. 10(a) and (b), the second pressure sensor based on the displacement of the reflecting surface of the conductor driven by the deflection change of the bourdon tube, wherein one end of the outer shell 1 and one end of the inner rod 2 of the sensor with the dielectric cavity are connected with the demodulating device 100; the other ends 4 of the outer shell 1 and the inner rod 2 are cut end faces, the end faces of the outer shell 1 and the inner rod 2 are on the same plane, the end faces are second reflection points, and the first reflection points and the second reflection points are fixed points; the first reflection point 3 is fixed between the end surfaces of the outer shell and the inner rod (second reflection point) and the demodulation device, the second reflection point 4 is the end surface of the outer shell or the inner rod, and the two reflection points are fixed points; the pressure intensity is measured by adopting the Bourdon tube 20, the pressure intensity acts on the pressurizing opening 23, and when the pressure intensity changes, a certain movement amount is generated on the end surface of the Bourdon tube 20 or a certain point on the Bourdon tube; studying the movement of the point A on the Bourdon tube, fixedly connecting a conductor reflecting surface 11 at the point A, wherein a carrier 15 of the conductor reflecting surface 11 is a rigid body, and the normal line of the conductor reflecting surface 11 is parallel to the moving direction of the Bourdon tube at the point A after the pressure intensity is changed; the conductor reflecting surface 11 is not contacted with the end surfaces of the shell 1 and the inner rod 2, or is connected with an insulator, or is connected with a conductor with the resistivity more than or equal to a preset threshold value, and has a smaller distance, namely the cavity length of the dielectric cavity 12; the space between the conductor reflecting surface 11 and the second reflecting point 4 is a dielectric cavity 12; the normal to the conductor reflecting surface 11 is parallel to the axes of the outer envelope 1 and the inner rod 2.

The cavity length measuring device of the dielectric cavity and the bourdon tube base 21 are fixed to a rigid object, i.e. they do not move relatively, or the bourdon tube 20 may be fixed to the housing 1 of the cavity length measuring device through the connecting member 21, the pressurizing port 23 is exposed to contact with the outside liquid or gas, and other parts are fixed in a closed cavity. Because the normal line of the conductor reflecting surface 11, the axes of the outer shell and the inner rod and the moving direction of the point A are all parallel, when the pressure intensity changes, the point A on the Bourdon tube moves to drive the conductor reflecting surface 11 to move along the axis direction of the inner rod of the outer shell, so that the distance between the conductor reflecting surface 11 and the second reflecting point 4 changes, namely the cavity length of the dielectric cavity changes, thereby changing and changing the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, and determining the cavity length variation of the dielectric cavity through the variation of the resonant frequency/the cavity length, thereby determining the pressure intensity. The types of bourdon tubes include C-type bourdon tubes, or helical bourdon tubes, or other shaped bourdon tubes, such as twist-type bourdon tubes, or circular bourdon tubes.

Compared with a diaphragm type pressure sensor, the pressure sensor with the same measuring range applies the same pressure, and the flexibility of the diaphragm is far smaller than a certain moving amount on the Bourdon tube, so that the sensitivity and the precision of the pressure sensor based on the Bourdon tube can be greatly improved. The bourdon tube type includes a C-type bourdon tube, as shown in fig. 10 (a); for higher sensitivity, the bourdon tube may be a bourdon tube having various shapes such as a C-type combination bourdon tube, a helical bourdon tube, a twist-type bourdon tube, or a circular bourdon tube. Wherein the helical bourdon tube is shown in fig. 10(b), and the axis of the helix coincides with the axial direction of the rod in the housing. The Bourdon tube with other shapes can also be used, and the requirement of measuring the pressure by using the flexibility of the tube can be met as long as the Bourdon tube is a bent tube or a folded tube.

Example three: acceleration sensor

Fig. 11 is a schematic view of an acceleration sensor according to an embodiment of the present application, in which a demodulation apparatus 100 is connected to one end of a housing 1 and an inner rod 2; the other end of the shell is connected with structures with certain rigidity, such as a diaphragm or a beam 15 and the like, which can be hinged or rigidly connected, the connecting material 13 can be a conductor or an insulator, and the projection of the reflecting surface 11 of the conductor and the envelope area of the shell 1 on the normal plane of the axis of the rod in the shell has a certain intersection; the first reflection point 3 is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point 4 is an end surface plane 4 of the outer shell or the inner rod, and the two reflection points are fixed points; the first side of the diaphragm or beam 15 close to the shell 1 and the inner rod 2 is a conductor reflecting surface 11; there is no conductor connection between the end face of the inner rod 2 and the first side of the diaphragm or beam 15, there is a small distance, and the region between the end face 4 of the inner rod and the first side 11 of the diaphragm is the dielectric cavity 12. A mass 27 having a mass m is fixed to the center of the second side of the diaphragm or beam 15, and when the mass 27 has an axial acceleration a, it exerts a force F, F ═ ma on the diaphragm or beam. The deflection of the central point of the diaphragm or the beam 15 is changed, so that the distance between the conductor reflecting surface 11 and the second reflecting point 4 is changed, that is, the cavity length of the dielectric cavity 12 is changed, and finally, the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed. The cavity length variation of the dielectric cavity can be determined through the variation of the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, and therefore the acceleration is determined.

The diameter of the diaphragm or the length of the beam is equal to the outer diameter of the shell or the outer diameter of an expanded diameter area of the end face of the shell, the sensitivity of the acceleration sensor can be reduced by increasing the thickness of the diaphragm, or increasing the rigidity of the beam, or reducing the weight of the mass block, and the acceleration sensor is suitable for measuring wide-range acceleration; the diaphragm is enlarged in diameter or the beam is enlarged in length, the thickness of the diaphragm is reduced or the rigidity of the beam is reduced, the weight of the mass block is increased, the sensitivity of the acceleration sensor can be increased, and the acceleration sensor is suitable for measuring small-range acceleration. When the diameter of the diaphragm is increased, the diaphragm can be realized by adopting an expanding structure such as a bell mouth or a conductor with the expanded diameter and the like added on the end surface of the shell, and the outer ring of the diaphragm is hermetically connected with the end surface of the expanding structure; when the length of the beam is increased, the end surface of the shell is respectively added with a cantilever support to two sides along the diameter direction, the end surfaces of the two supports are used as two fulcrums of the beam and are connected by adopting a connecting piece 13, and the two ends can be rigidly connected or can be made into a simply supported beam with the two ends hinged; or the cantilever beam is made, a mass block is fixed on the end face of the cantilever beam, and a conductor reflecting surface is arranged on one side of the mass block close to the end faces of the shell and the inner rod.

Example four: flow rate sensor

Two flow rate sensors are introduced, the first is to utilize the fluid to generate additional pressure near the baffle plate, and the flow rate is measured by measuring the additional pressure by using the pressure sensor in the second embodiment; the second method is to use different flow rates to generate different thrust forces, and determine the flow rate by measuring the magnitude of the force.

Fig. 12(a) and (b) show a first pressure-measuring-based flow rate sensor according to an embodiment of the present application, which is modified by using the pressure sensor described in the second embodiment, and the flow rate is obtained by measuring the pressure using different pressures generated by different flow rates. In the case that the fluid moves from left to right, a baffle 31 is fixed on the right side beside the pressure sensor in fig. 12(a), so that when the fluid 15 impacts the baffle, additional pressure is generated at the position where the pressure sensor is displaced, the additional pressure on the left side of the baffle is measured by using different deflections of the diaphragm 15 of the pressure sensor fixed on the left side of the baffle under different pressures, and the flow rate is determined according to the magnitude of the additional pressure. The pressure sensor can be a diaphragm type pressure sensor, and can also be a Bourdon tube type pressure sensor. When the axis of the pressure sensor forms an angle with the flowing direction of the fluid 15, the flow rate can be reflected directly by measuring the pressure without using a baffle, as shown in fig. 12 (b). The pressure sensor may use the diaphragm type pressure sensor or the bourdon tube type pressure sensor described in embodiment two. The flow velocity sensor at least comprises a plate hole flow velocity sensor or a U-shaped pipe differential pressure flow velocity sensor and other flow velocity sensors with different structures.

Fig. 12(c) shows a second force-measuring-based flow velocity sensor according to the embodiment of the present application, in which a first reflection point is fixed between the end surfaces of the outer shell and the inner rod and the demodulation apparatus 100, a second reflection point 4 is the end surface of the outer shell or the inner rod, and both the first reflection point and the second reflection point are fixed points; when the flow rate is different, the pushing force on the probe 38 inserted into the fluid is different, so that the moving distance of the probe is changed, and one point on the probe rotates around a hinge 39, the hinge is fixed on the shell 1 of the sensor through a connecting part 37, the other end of the probe is connected with the carrier 15 of the conductor reflecting surface 11, the conductor reflecting surface 11 is not contacted with the inner rod end surface (second reflecting point) 4, or is connected with an insulator, or is connected with a conductor with the resistivity larger than or equal to a preset threshold value, the conductor reflecting surface 11 is connected with the shell 1 through an elastic material, and the elastic material can be a conductor or an insulator. When measuring, the first principle is as follows: when the elastic medium 13 is connected between the outer shell 1 and the conductor reflecting surface 11, the probe 38 is driven to rotate by moving, so that the other end 39 of the probe is driven to move in the opposite direction, the carrier 15 of the conductor reflecting surface 11 is driven to move, the elastic material 13 between the conductor reflecting surface 11 and the outer shell 1 is stretched or compressed, the distance from the conductor reflecting surface 11 to the second reflecting point 4 on the end surface of the inner rod is changed, and the cavity length of the dielectric cavity 12 is changed; the second principle is that: 13 is a material with larger rigidity, only has a tiny stretching or compressing amount when stressed, the carrier 15 of the conductor reflecting surface 11 is a thin membrane, the force generated by the fluid pushing probe 38 drives the other end 39 of the probe rod to move reversely, the central point of the membrane is extruded by the hinged part 40 connected with the carrier of the second reflecting point, the deflection of the membrane 15 changes, the cavity length of the dielectric cavity changes, and finally the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity changes. The cavity length variation of the dielectric cavity, namely the deflection variation of the diaphragm, is determined by measuring the resonant frequency/resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, so that the flow velocity is determined. According to the two principles, the larger the flow velocity is, the larger the thrust generated to the probe is, the larger the stretching or compressing amount of the flexible conductor material is, or the larger the deflection of the central point of the diaphragm is, the larger the cavity length variation of the dielectric cavity is; the cavity length between the second reflection point 4 and the conductor reflection surface 11, namely the cavity length of the dielectric cavity 12 is determined by measuring the variation of the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, so that the flow velocity is determined.

Example five: force measuring machine

Two types of load cells are described herein which can be made using the stiffness and deformation of the housing, or using the stiffness and deflection of the end beams or diaphragms of the housing.

As shown in fig. 13(a), the first dynamometer, which is a small-range dynamometer made by using the rigidity and deflection of the beam or diaphragm 15 connected to the end face of the housing 1, has a similar overall structure to the acceleration sensor described in the third embodiment. One end of the shell 1 and one end of the inner rod 2 are connected with the demodulating device 100; the other end of the shell 1 is connected with structures with certain rigidity, such as a diaphragm or a beam 15, and the like, and the connecting materials can be conductors or insulators; the first reflection point is fixed between the end faces of the outer shell and the inner rod and the demodulation device 100, the second reflection point is the end face of the outer shell 1 or the inner rod 2, and both the two reflection points are fixed points, so that the distance variation between the second reflection point 4 and the conductor reflection surface 11 is equal to the distance variation between the first reflection point 3 and the conductor reflection surface 11; the first side of the diaphragm or beam 15 close to the shell 1 and the inner rod 2 is a conductor reflecting surface 11; the end face of the inner rod 2 is in conductor-free connection with the dielectric cavity 12 between the first side 11 of the diaphragm or beam 15, at a small distance. When the central point of the diaphragm or the beam 15 is subjected to an acting force F, the deflection of the central point of the diaphragm or the beam 15 changes, so that the distance between the conductor reflecting surface 11 and the inner rod end surface (second reflecting point) 4 changes, that is, the cavity length of the dielectric cavity changes, and finally the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity changes. The cavity length variation of the dielectric cavity between the second reflection point 4 and the conductor reflection surface 11 can be determined by the resonance frequency/cavity length variation, thereby determining the magnitude of the force.

As shown in fig. 13(b), the second load cell is a large-range load cell made using the rigidity and deformation of the housing 1. One end of the outer shell and one end of the inner rod are connected with the demodulating device 100; the other end of the shell is connected with a conductor reflecting surface 11, and a carrier 36 of the conductor reflecting surface can be very thick and is approximately regarded as a rigid body; the first reflection point 3 is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device, the second reflection point 4 is the end surface of the inner rod 2, and both the two reflection points are fixed points, so that the distance variation between the second reflection point 4 and the conductor reflection surface 11 is equal to the distance variation between the first reflection point 3 and the conductor reflection surface 11; the conductor reflecting surface 11 is fixed with the shell 1 and is not contacted with the inner rod 2, and the end surface of the inner rod 2 has a certain distance from the conductor reflecting surface; when the carrier 36 of the conductor reflecting surface 11 is subjected to tensile force or pressure, the housing 1 is stretched or compressed, the elasticity of the housing material is E, the net area of the material tensile and compression area is a, the distance from the first reflecting point 3 to the conductor reflecting surface 11 is L, the resonance frequency occurs after the force is applied, the cavity length variation of the dielectric cavity between the second reflecting point 4 and the conductor reflecting surface 11 can be determined through the resonance frequency/cavity length variation of the open type hollow coaxial cable-fabry-perot resonant cavity, so that the distance variation between the conductor reflecting surface and the inner rod end surface (second reflecting point) is Δ d, and the obtained acting force is F ═ EA · Δ d/L.

Example six: strain gauge

As shown in fig. 14, the sensor has a first reflection point 3, a second reflection point 4, and a conductor reflection surface 11, the first reflection point 3 is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device 100, the second reflection point 4 is the end surface of the outer shell 1 or the inner rod 2, and both the first reflection point and the second reflection point are fixed points; wherein, the structure of the fixed bulge outside the shell near the first reflection point 3 is used as the first fixed point 41, and normally, the first reflection point 3 and the first fixed point 41 are at the same position or not far away; the structure of the housing external fixing protrusion at the conductor reflection surface 11 serves as a second fixing point 42, and normally, the conductor reflection surface 11 and the second fixing point 42 are at the same position or are not far apart. The distance between the first fixing point 41 and the second fixing point 42 is L; the second reflection point 4 is the end surface of the inner rod 2 and is at a certain distance from the conductor reflection surface 11, the second reflection point 4 is not in contact with the conductor reflection surface 11, the middle part is a dielectric cavity 12, and solid or liquid can be filled in the dielectric cavity between the second reflection point 4 and the conductor reflection surface 11; the demodulating apparatus 100 is connected to one end of the housing 1 and the inner rod 2 or to a wall of the housing. The shell 1 can be formed by two sections of conductor materials, and the two sections of shells are connected by adopting a nested structure or a conductor corrugated pipe 43 and other structures; the shell 1 can also be not segmented, and when the strain changes, the shell material stretches or compresses; the inner rod is a rigid body and is not segmented, and the second reflecting surface 4 is the end surface of the inner rod.

The strain gauge can be fixed on an object to be detected or embedded in a medium to be detected through the first fixed point 41 and the second fixed point 42, for example, fixed on a steel bar or in concrete, the initial distance between the first fixed point 41 and the second fixed point 42 is L, the object to be detected or the medium to be detected can be strained, the two fixed points can be driven to move relatively delta d, so that the first reflection point 3 and the conductor reflection surface 11 are driven to move relatively delta d, the distance between the first reflection point 3 and the second reflection point 4 is fixed, so that the relative displacement between the first reflection point 3 and the conductor reflection surface 11 is equal to the relative displacement between the second reflection point 4 and the conductor reflection surface 11, namely, the cavity length of the dielectric cavity is changed, and the change of the resonant frequency/the cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity can determine that the second reflection point 4 is opposite to the conductor anti-reflection surface The amount of change Δ d in the cavity length of the dielectric cavity between the incident surfaces 11 is obtained as a change Δ d in the distance from the conductor reflecting surface to the end surface of the inner rod, and the magnitude of strain is obtained as ∈ Δ d/L.

Example seven: tilt meter

1) First horizontally-placed unidirectional inclinometer based on flexible rope or elastic rod

The sensor is internally provided with a first reflection point 3, a second reflection point 4 and a conductor reflection surface 11, the first reflection point 3 is fixed between the end surfaces of the outer shell and the inner rod and the demodulation device 100, the second reflection point 4 is the end surfaces of the outer shell 1 and the inner rod 2, and the first reflection point and the second reflection point are both fixed points; preferably, the end surfaces of the outer shell 1 and the inner rod 2 are the same cross section, which is the second reflection point 4. A bracket 54 is fixed on the housing 1 for hanging a flexible rope or an elastic rod 53 with two hinged ends, and a weight 52 is hung below the flexible rope or the elastic rod 53 with two hinged ends. The first end face of the weight 52 close to the end faces 4 of the housing 1 and the inner rod 2 is a conductor reflecting surface 11 made of a conductor material. When the measured object drives the inclinometer to incline, the support 54 and the second reflection point 4 incline along with the measured object, the conductor reflection surface 4 and the weight 52 keep the original state or only rotate under the action of gravity, so the conductor reflection surface 4 and the weight 52 can move left relative to the second reflection point 4, the distance between the conductor reflection surface 11 and the second reflection point 4 changes, namely the cavity length of the dielectric cavity 12 changes, finally the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity changes, and the cavity length variation of the dielectric cavity 12 can be determined through the variation of the resonant frequency/the cavity length, so that the size of the inclination angle is determined. As shown in fig. 15(a), the first condition: when the conductor reflecting surface 11 is placed in parallel with the end surface corresponding to the second reflecting point 4, a heavy object is hung by adopting two or more parallel flexible ropes with equal length or elastic rods 53 with two hinged ends, which are placed at the left and the right, and a plane formed by the four connecting points of the flexible ropes or the elastic rods 53, the bracket 54 and the heavy object is parallel to the axes of the shell and the inner rod; when the connecting line of the fixed points of the equal-length flexible ropes or the elastic rods 53 with two hinged ends on the support 54 is not perpendicular to the axes of the shell 1 and the inner rod 2, after the inclination angle is changed, the end surfaces of the conductor reflecting surface 11 corresponding to the second reflecting point 4 are always parallel, and the measurement and calibration are more convenient. Preferably, two flexible cords of equal length or two articulated ends 42 are used, and the line connecting the fixing points of the two flexible cords or two articulated ends 53 to the support 54 is parallel to the axis of the outer casing 1 and the inner rod 2. At this time, the length of the flexible rope or the elastic rod 53 with two hinged ends is L, when the inclination angle of the inclinometer changes on the plane formed by the two flexible ropes or the elastic rods 53 with two hinged ends, the conductor reflecting surface 11 is always parallel to the end surfaces of the shell 1 and the inner rod 2, the distance variation between the second reflecting point 4 and the conductor reflecting surface can be obtained through the resonance frequency/resonant cavity length variation, namely, the cavity length variation of the dielectric cavity is Δ d, and thus the variation of the inclination angle is Δ θ ═ arcsin (Δ d/L).

As shown in fig. 15(b), the second condition: the weight is hung by adopting two equal-length flexible ropes 53 which are arranged in front and back, and the plane formed by the two flexible ropes and four fixing points which are directly connected with the weight is vertical to the axes of the shell and the inner rod; or the elastic rods 53 with two ends rigidly connected are adopted, the number of the elastic rods can be one elastic rod, or two elastic rods, or a plurality of elastic rods, and the two ends of the elastic rods are rigidly connected with the bracket and the heavy object. The length of the flexible rope or the elastic rod 53 with two ends connected rigidly is L, the weight 52 is hung at the bottom, and after the inclination angle is changed, the included angle between the conductor reflecting surface 11 and the end surface corresponding to the second reflecting point 4 can be changed. The length of the flexible rope or the elastic rod with two ends connected rigidly is L, when the inclination angle of the inclinometer changes on the plane formed by the two flexible ropes or the elastic rods 53 with two ends connected rigidly, the cavity length variation Δ d of the dielectric cavity 12 between the second reflection point 4 and the conductor reflection surface 11 can be obtained through the resonance frequency/cavity length variation of the open hollow coaxial cable-fabry-perot resonant cavity, and the relation between the distance variation Δ d and the inclination angle variation Δ θ needs to be obtained through calibration.

2) First horizontally-placed bidirectional inclinometer based on flexible rope or elastic rod

As shown in fig. 16, a cavity length measuring device employing two non-parallel and horizontally disposed dielectric cavities is rigidly secured to the top, bottom or side walls 58, respectively, of the inclinometer. The two cavity length measuring devices 101, the outer shell and the inner rod are on the same end face, and the end face serves as a second reflection point. In the first working condition, at least three or more flexible ropes with equal length and parallel length or elastic rods 53 with hinged ends are fixed on the top plate 58, and the flexible ropes or the elastic rods 53 with hinged ends are not in the same straight line with all the fixed points of the top plate 58 or the weight 55, at this time, the cavity length variation of the dielectric cavity is only related to the rope length/rod length and the inclination angle, and is unrelated to the number and the position of the ropes or rods, and for convenience of processing, the three flexible ropes with parallel and equal length or the elastic rods with hinged ends are preferably used. A weight 55 is hung at the bottom of the flexible rope with equal length or the elastic rod 53 with two hinged ends, and the weight 55 is provided with vertical surfaces which are parallel to the flexible rope with equal length or the elastic rod 53 with two hinged ends and are respectively used as conductor reflecting surfaces 11 of the two cavity length measuring devices and made of conductor materials; in the second working condition, one or more elastic rods are used for rigidly connecting the top plate and the heavy object, and the normals of the two conductor reflecting surfaces on the heavy object are not parallel;

the first working condition is as follows: the top plate 58 and the weight 55 are connected by using three parallel and equal-length flexible ropes or elastic rods 53 with two hinged ends, and two triangles formed by the three fixing points of the flexible ropes or the elastic rods and the top plate and the weight are congruent triangles. Fixing the inclinometer on a measured object, and using three parallel and equal-length flexible ropes or elastic rods 53 with two hinged ends for convenient processing, wherein the length of the flexible ropes or the elastic rods with two hinged ends is L; or three elastic rods 53 with equal length are used, and the elastic rods are hinged with the top plate 58 and the weight 55. When the three flexible ropes or the elastic rods 55 hinged at two ends are not on the same straight line with the three intersection points of the top plate and the heavy object, the two inclination directions are respectively inclination around the X axis and inclination around the Y axis; a weight 11 is hung below the three ropes, wherein normals of the weight as two surfaces of the conductor reflecting surface 11 are an X axis and a Y axis respectively. The end surfaces of the inner rods of the shells of the two cavity length measuring devices 101 are on the same section, the axes are respectively vertical to the two conductor reflecting surfaces 11, and the end surfaces of the shells and the inner rods of the two cavity length measuring devices and the two conductor reflecting surfaces are kept to be certainI.e. the cavity length of the dielectric cavity. When the inclinometer inclines around the X axis and the Y axis, the distance between the second reflection point of the two cavity length measuring devices and the conductor reflection surface changes, so that the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity changes, and the cavity length variation quantity of the dielectric cavity 12 between the second reflection point 4 of the two cavity length measuring devices and the conductor reflection surface 11 is respectively delta d₁And Δ d₂. The cavity length variation deltad of the dielectric cavity between the second reflection point of the first cavity length measuring device and the conductor reflection surface₁And the length L of the rope or rod, the variation delta theta of the inclination angle of the inclinometer around the X axis can be determined₁＝arcsin(Δd₁L); the cavity length variation deltad of the dielectric cavity between the second reflection point of the second cavity length measuring device and the conductor reflection surface₂And the length L of the rope or the rod, the change quantity delta theta of the inclination angle of the inclinometer around the Y axis can be determined₂＝arcsin(Δd₂L). As long as the flexible ropes or the elastic rods hinged at the two ends are parallel and equal in length, the number of the flexible ropes or the elastic rods hinged at the two ends is more than or equal to 3, and the connecting lines of the flexible ropes or the elastic rods 57 hinged at the two ends and the fixed points of the top plate 58 and the heavy object 55 are not in the same straight line, the inclination angles in the two directions can be obtained by using the calculation method of the working condition. When three or more elastic rods which are not in a straight line with the fixed point of the top plate and are parallel and equal in length are used for connecting the top plate and the heavy object in a hinged mode, the calculation method is the same as that under the first working condition;

the second working condition is as follows: the top plate 58 and the weight 55 are rigidly connected by the elastic rod 53, the inclinometer is fixed on the measured object by one elastic rod, or two elastic rods, or more than three elastic rods, the length of each elastic rod is L, and the elastic rod 53 is rigidly connected with the top plate and the weight. When the inclinometer is inclined around the X axis and the Y axis, the cavity length variation delta d of the dielectric cavity 12 between the second reflecting point 4 and the conductor reflecting surface 11 can be obtained through the variation of the resonant frequency of the two cavity length measuring devices₁And Δ d₂The cavity length variation delta d of the two dielectric cavities needs to be obtained through calibration₁、Δd₂And the inclination angle variation amount delta theta₁、Δθ₂The relationship between them.

The calculation method is the same as the first working condition when three or more elastic rods which are not in a straight line with the fixed point of the top plate are used for connecting the top plate and the heavy object in a hinged mode.

3) Second one-way clinometer based on pressure sensor

As shown in fig. 17(a), a unidirectional inclinometer is made by using two pressure sensors based on the principle of pressure difference, the inclinometer comprises a closed container 59 fixed on a measured object, the bottom of the closed container is provided with a liquid 33 with a certain depth, and the inclination angle is determined by using the pressure difference of the two pressure sensors after inclination, so that the influence of temperature can be eliminated without temperature compensation. With the pressure sensor described in the second embodiment, the external end face structure may be a counterbored or non-counterbored structure, or a bourdon tube pressure sensor may be used.

When the two pressure sensors are rigidly fixed to the top plate, the bottom plate or the side surface inside the container, the two pressure sensors rotate along with the inclination of the measured object. The two pressure sensors are placed on the left and right, the axes of the two pressure sensors are parallel, and the parallel distance between the two axes is d. The end faces of the outer shell and the inner rod are below, and the two pressure measuring membrane sheets 15 or bourdon tube end membrane sheets are immersed in the liquid and equally distanced from the bottom of the container 59. When the object to be measured drives the closed container 59 to incline in the plane formed by the axes of the two pressure sensors, the depth of the two pressure sensors immersed in the liquid can change, so that the pressure measured by the two pressure sensors can change; and because the axes of the two pressure sensors are always parallel, the distance between the axes of the two pressure sensors can also change along with the change of the inclination angle. Determining the cavity length variation of a dielectric cavity 12 between a second reflection point 4 and a conductor reflection surface 11 by measuring the resonance frequency/cavity length variation of an open type hollow coaxial cable-Fabry-Perot resonant cavity, obtaining the pressure variation of two pressure sensors according to the data calibrated by the pressure sensors, and solving the variation delta L of the immersion depth₁And Δ L₂，ΔL₁And Δ L₂With a sign, the final determinationThe amount of change in the tilt angle is Δ θ ═ arctan [ (Δ L)₂-ΔL₁)/d]。

When the tops of two pressure sensors placed left and right are connected to the top plate inside the container 59 through flexible ropes or elastic rods 53 with two hinged ends, the distance between two fixed points is d, and under the action of gravity, the axes of the two pressure sensors are always vertical and do not rotate along with the inclination of the measured object. The end faces of the outer shell and the inner rod are below and the two pressure diaphragms or bourdon tube end face diaphragms 15 are immersed in the liquid 33 and are equally distanced from the bottom of the container. When the object to be measured drives the closed container to incline in a plane formed by the axes of the two pressure sensors, the depth of the two pressure sensors immersed in the liquid also changes, so that the pressure measured by the two pressure sensors also changes, and the variation delta L of the immersion depth is calculated according to the variation of the pressure of the two pressure sensors₁And Δ L₂Finally, the amount of change in the tilt angle Δ θ ═ arcsin [ (Δ L) can be determined₂-ΔL₁)/d]。

4) Second two-way clinometer based on pressure sensor

As shown in fig. 17(b), a bidirectional inclinometer is made by using three pressure sensors based on the principle of pressure difference, the inclinometer comprises a closed container fixed on a measured object, the bottom of the closed container is provided with a certain depth of liquid, and the inclination angle is determined by using the pressure difference of the three pressure sensors after inclination, so that the influence of temperature can be eliminated without temperature compensation.

When the three pressure sensors are rigidly fixed inside the container, the three pressure sensors rotate with the inclination of the object to be measured. As long as the axes of the three pressure sensors and the three intersection points of the horizontal plane are not on the same straight line, the pressure sensors can be made into bidirectional inclinometers; the bottom of the closed container is filled with liquid, and the three pressure sensor pressure measuring diaphragms or Bourdon tube end diaphragms are immersed in the liquid and are equally spaced from the bottom of the container. When the three intersection points of the axes of the three pressure sensors and the horizontal plane form a right triangle, the two right-angle sides are respectively the X axis and the Y axis in the inclined direction, and the structure is convenient to calibrate and addManufacturing, and with a preferred structure, the distribution diagram of the three pressure sensors is shown in fig. 17 (b); the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a When the inclinometer inclines around the X axis and the Y axis, the depth of the first pressure sensor and the second pressure sensor immersed in the liquid changes, so that the pressures measured by the two pressure sensors change, and the variation delta L of the immersion depth is calculated according to the pressure variation of the two pressure sensors₁And Δ L₂According to the parallel spacing d₁Can determine the variation of the inclination angle of the inclinometer around the X axis as delta theta₁＝arctan[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the variation of the inclination angle of the inclinometer around the Y axis as delta theta₂＝arctan[(ΔL₃-ΔL₂)/d₂]。

When the tops of the three pressure sensors are connected to a top plate in the container through flexible ropes or elastic rods with two hinged ends, under the action of gravity, the axes of the three pressure sensors are always vertical and do not rotate along with the inclination of a measured object. The three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the three pressure sensor pressure measuring diaphragms or Bourdon tube end diaphragms are immersed in the liquid and are equally spaced from the bottom of the container. When the three intersection points of the axes of the three pressure sensors and the top plate form a right triangle, the two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a When the inclinometer inclines around the X axis and the Y axis, the depth of the first pressure sensor and the second pressure sensor immersed in the liquid changes, so that the pressures measured by the two pressure sensors change, and the variation delta L of the immersion depth is calculated according to the pressure variation of the two pressure sensors₁And Δ L₂According to the parallel spacing d₁Can determine the variation delta theta of the inclination angle of the inclinometer around the X axis₁＝arcsin[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the variation delta theta of the inclination angle of the inclinometer around the Y axis₂＝arcsin[(ΔL₃-ΔL₂)/d₂]。

Example eight: slippage sensor

1) One-way slip meter

As shown in fig. 18(a), two cavity length measuring devices of the dielectric cavity for measuring the distance from the second reflection point 4 to the conductor reflection surface 11 are used as a slip meter for measuring the unidirectional horizontal slip amount and the longitudinal separation amount, and the medium a is studied to be equivalent to the relative displacement of the medium B in the axial direction and the normal direction. 64 is a medium A fixed to the slippage meter carrier 61; 65 is medium B immobilized with double-inclined carrier 63; the two electric cavity length measuring devices are respectively a first cavity length measuring device and a second cavity length measuring device. The end faces of the conductor areas of the housing 1 and the inner rod 2 of each displacement sensor are in a plane, i.e. the plane in which the second reflection point 4 is located, and the plane is parallel to the conductor reflection surface 11. The two inclined holes are two inclined holes of the slippage meter carrier 61 fixed on the medium A, and respectively pass through and fix the shells of the first cavity length measuring device and the second cavity length measuring device, and the axes of the two inclined holes are vertical to the two inclined planes. The double inclined planes are inclined planes made of two conductor materials of a double inclined plane carrier 63 fixed on the medium B, and are respectively a first inclined plane and a second inclined plane, and the two inclined planes of the double inclined planes are respectively a first conductor reflecting plane and a second conductor reflecting plane corresponding to the first cavity length measuring device and the second cavity length measuring device.

The slippage meter carrier 61 is fixed on the medium A, a shell of a first cavity length measuring device is fixed in a first inclined hole of the slippage meter carrier 61, a shell of a second cavity length measuring device is fixed in a second inclined hole of the slippage meter carrier 61, the end surfaces of the shell and the inner rod of the first cavity length measuring device are opposite and parallel to a first inclined surface, the end surfaces of the shell 1 and the inner rod 2 of the second cavity length measuring device are opposite and parallel to a second inclined surface, the first inclined surface and the second inclined surface are two inclined surfaces of a double-inclined-surface carrier 63, and the double-inclined-surface carrier 63 is fixed on the medium B; a second-order matrix formed by normal vectors of the two inclined planes

the first cavity length measuring device is used for measuring the distance variation of the second reflecting point 4 of the device to the first conductor reflecting surface 11 (first inclined plane), namely the cavity length variation of the dielectric cavity is deltad₁And the second cavity length measuring device is used for measuring the distance variation of a second reflecting point 4 of the device to a second conductor reflecting surface 11 (a second inclined plane), namely the cavity length variation of the dielectric cavity is delta d₂. Two distance variations, i.e. the cavity length variation of the dielectric cavity Δ d₁And Δ d₂The resonant frequency/the resonant cavity length of the Fabry-Perot resonant cavity can be obtained through the open type hollow coaxial cable. By the two distance variations (cavity length variations of the dielectric cavity) and the normal vectors of the two slopes, the horizontal slip amount Δ x and the longitudinal separation amount Δ z of the medium a with respect to the medium B can be obtained:

fig. 18(a) is a schematic view of a one-way slip meter according to an embodiment of the present application. This example investigated the relative amount of horizontal slip and the relative amount of longitudinal displacement of media a relative to media B. It is common practice to study the relative slippage between steel members and concrete, for example: a represents concrete, and B represents a steel member. The one-way slip meter mainly comprises: two cavity length measuring devices; a double bevel; a carrier 61 with two inclined holes for fixing the cavity length measuring device is fixed on the shell 1 of the cavity length measuring device, an inner rod can pass through the two inclined holes on the carrier 61, and the two inclined holes are respectively vertical to the two inclined planes 11 of the double-inclined-plane carrier 63; the sealing device 62 of the sliding meter is generally made of a softer material, so that the phenomenon that objects such as water vapor, dust and the like are immersed when the upper half part of the sliding meter slides relative to the lower half part of the sliding meter is prevented; the carrier 63 of the double-inclined surface of the lower half part of the slip meter is fixed on the medium B; the two double inclined planes are arranged on the double inclined plane carrier 63, the two inclined planes can be at the same angle or different angles, and the angle range can be between-90 degrees and 90 degrees; 64 is medium A to which carrier 61 is fixed.

2) Bidirectional slippage meter

As shown in fig. 18(b), the principle of the one-way slip meter is the same, except that a third slope is added. Three cavity length measuring devices of the dielectric cavity for measuring the distance between the second reflection point 4 and the conductor reflection surface 11 are used to make a slippage meter for measuring the bidirectional horizontal slippage and the longitudinal separation, and the relative displacement of the medium A corresponding to the medium B in two directions and the normal direction of the plane is researched. The end faces of the outer shell and the inner rod conductor region of each cavity length measuring device are on a plane, namely a plane where the second reflection point is located, and the plane is parallel to the conductor reflection surface, namely the inclined surface. The three inclined holes are fixed on the medium A and are used for fixing the shells of the first cavity length measuring device, the second cavity length measuring device and the third cavity length measuring device respectively, and the axes of the three inclined holes are perpendicular to the three inclined planes. The three inclined planes are fixed on a three-inclined-plane carrier on the medium B and are respectively a first inclined plane, a second inclined plane and a third inclined plane, and the three inclined planes of the three inclined planes are respectively a first conductor reflecting plane, a second conductor reflecting plane and a third conductor reflecting plane corresponding to the first cavity length measuring device, the second cavity length measuring device and the third cavity length measuring device.

The three cavity length measuring devices are fixed in the three inclined holes through the shells, and the end surfaces of the shells and the inner rod of the three cavity length measuring devices, namely the second reflection points, are respectively parallel to the three inclined surfaces; the third-order matrix formed by the normal vectors of the three inclined planes

Is equal to 3, wherein the normal vector of the first slope is (l)₁,m₁,n₁)^TThe normal vector of the second inclined plane is (l)₂,m₂,n₂)^TThe normal vector of the third inclined plane is (l)₃,m₃,n₃)^TThe inclination angle theta of the three inclined planes relative to the horizontal plane₁、θ₂And theta₃Between-90 ° and 90 °;

the first cavity length measuring device is used for measuring the distance variation of a second reflecting point of the device to a reflecting surface (a first inclined surface) of the first conductor, namely the cavity length variation of the dielectric cavity is delta d₁And the second cavity length measuring device is used for measuring the distance variation from a second reflecting point of the device to a reflecting surface (a second inclined surface) of the second conductor, namely the cavity length variation of the dielectric cavity is delta d₂And the third cavity length measuring device is used for measuring the distance variation from the second reflecting point of the device to the reflecting surface (third inclined surface) of the third conductor, namely the cavity length variation of the dielectric cavity is delta d₃(ii) a Three distance variations, i.e. the cavity length variation of the dielectric cavity Δ d₁、Δd₂And Δ d₃The resonant frequency/the resonant cavity length of the Fabry-Perot resonant cavity can be obtained through the open type hollow coaxial cable. By the three distance variations (cavity length variations of the dielectric cavity) and the normal vectors of the three slopes, the horizontal slip amounts Δ x, Δ y and the longitudinal separation amount Δ z of the first object with respect to the second object can be obtained:

example nine: displacement sensor

1) Displacement sensor based on spring and diaphragm

As shown in fig. 19(a) and (b), the displacement sensor converts a large displacement variation into a small diaphragm deflection variation through the spring 72 and the diaphragm 15; the side of the diaphragm 15 close to the cavity length measuring means of the dielectric cavity is the conductor reflecting surface 11. The displacement sensor is implemented using a cavity length measuring device of the dielectric cavity for measuring the distance from the second reflection point 4 to the conductor reflection surface 11. The left end surfaces of the outer shell 1 and the inner rod 2 of the cavity length measuring device are connected with a demodulating device, the right end surface is a second reflection point 4, a diaphragm 15 is arranged at a certain distance on the right side of the second reflection point 4, the normal line of the diaphragm 15 is overlapped with the axis of the inner rod in the outer shell, and the left end surface of the diaphragm 15 is a conductor reflecting surface 11. The right end face of the diaphragm 15 is a push rod 71 which is pressed against the center point of the diaphragm, a supporting structure is arranged on the right side of the push rod, a spring 72 is arranged on the right side of the supporting structure, a supporting structure 73 is also arranged on the right side of the spring, and the supporting structure and the probe rod 74 are one part.

When the displacement changes, the probe rod 73 moves, the compression amount of the spring 72 changes, the elastic force changes, the force acting on the diaphragm 15 changes through the push rod 71, and finally the deflection of the diaphragm 15 changes, so that the distance between the conductor reflecting surface and the second reflecting point changes, namely the cavity length of the dielectric cavity changes, and finally the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity changes. Through calibration, the relation between the resonant frequency/the length and the displacement of the resonant cavity can be obtained.

When the end face of the housing 1 has a flare, the diameter of the diaphragm can be increased to increase the sensitivity of the displacement sensor, as shown in fig. 19 (b).

2) Displacement sensor for displacement reduction based on inclined plane

Fig. 20(a) is a schematic view of a reflective displacement sensor for reducing displacement by an oblique surface according to an embodiment of the present application. The method mainly comprises the following steps: in the first embodiment, the cavity length measuring system of the dielectric cavity, the inclined plane 81, the displacement sensor probe 74, the sealing ring 86 for sealing the end face of the probe, the housing 84 of the linear bearing, the linear bearing 85, the stop block body 83, the displacement sensor housing 82, the fixing device 87 for fixing the upper housing 1 of the cavity length measuring device, the anti-shake sliding block 88, the spring 72, and the sealing plug 89 for sealing the end face of the displacement sensor. The displacement sensor uses an inclined plane as a conductor reflecting surface 11, and the axes of the housing 1 and the inner rod 2 of the cavity length measuring device are perpendicular to the inclined plane 11. An included angle theta is formed between the inclined plane 11 and the horizontal displacement direction measured by the displacement meter, the range of the theta is between minus 90 degrees and 90 degrees, namely the inclined plane can incline leftwards and also can incline rightwards, the axis of the displacement meter is always perpendicular to the inclined plane, the larger the measuring range of the displacement meter is, the smaller the theta is. When the displacement changes, the displacement reduction principle is that a large displacement change amount in the horizontal direction is changed into a small movement amount in the normal direction of the inclined plane through the inclined plane, that is, the cavity length of the dielectric cavity 12 only changes slightly. Wherein the end faces of the conductor areas of the housing 1 and the inner rod 2 of the cavity length measuring device are in a plane, i.e. the plane in which the second reflection point 4 is located, and the plane is parallel to the conductor reflection surface 11, i.e. the axis of the cavity length measuring device is parallel to the normal of the inclined plane. The side of the inclined plane close to the displacement sensor is a conductor reflecting surface 11.

The inclination angle of the inclined plane is a known quantity theta, when the horizontal displacement of the displacement probe rod is w, the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity is changed, so that the distance variation from the second reflection point 4 of the cavity length measuring device to the conductor reflection plane/inclined plane 11 is obtained, namely the cavity length variation of the dielectric cavity is deltad which is w.sin theta. The change amount Δ d of the cavity length of the dielectric cavity between the second reflection point 4 and the conductor reflection surface 11 can be determined by the change amount of the resonant frequency/the cavity length of the resonant cavity, and the magnitude w of the displacement is Δ d/sin θ. The range of the displacement sensor can be increased by decreasing the slope of the ramp with the maximum and minimum of the cavity length of the dielectric cavity 12 unchanged.

3) Displacement sensor for displacement reduction based on folding lever structure

Fig. 20(b) is a schematic structural diagram of a displacement sensor for displacement reduction based on a folding lever structure according to an embodiment of the present application. The end face of the folded lever on the side with a small number of folds is fixed with a conductor reflecting surface 11, and a large displacement change amount in the axial direction can be changed into a small movement amount of the conductor reflecting mirror 11 in the axial direction. The demodulation device 100 is on the left, and sequentially comprises a demodulation device, a cavity length measuring device of a dielectric cavity, a conductor reflector, M folding fixed points, N folds and a probe rod from left to right. The end faces of the housing 1 and the inner rod 2 of the dielectric cavity length measuring device are on a plane, namely the plane where the second reflection point 4 is located, and the plane is parallel to the conductor reflection surface 11, namely the axis of the dielectric cavity length measuring device is perpendicular to the conductor reflection surface 11, and the axis of the dielectric cavity length measuring device and the moving direction of the folded end face probe rod are the same.

The displacement is reduced by folding the lever structure. The folding lever is provided with a plurality of rotating shafts, and because the cavity length variation of the dielectric cavity 12 between the second reflecting point 4 of the dielectric cavity length measuring device and the conductor reflecting surface 11 is smaller, the fixed rotating shaft 91 of the folding lever structure is close to the conductor reflecting surface 11, namely the number of corresponding folds from the fixed rotating shaft 91 to the conductor reflecting surface 4 is smaller, M folds are provided, and one folding structure 92 is commonly used; the number of folds of the folded portion of the fixed rotating shaft 91 to the displacement sensor probe 95 is large, and N folds are provided. In addition, the length of the rods of each folded structure may be varied. In general, the fold of the folded fixing point to the displacement sensor probe is longer, half the length of each fold being L; the fixing point of the folds to the corresponding folds of the conductor mirror is short, half the length of each fold being a. At this time, the displacement amount of the right probe rod movement is w, and the variation amount of the distance between the second reflection point 4 and the conductor reflection surface 11, that is, the cavity length variation Δ d of the dielectric cavity is:

the displacement variation w is proportional to the cavity length variation Δ d of the dielectric cavity. The distance variation delta d between the second reflection point and the conductor reflection surface, namely the cavity length variation delta d of the dielectric cavity can be determined through the variation of the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity. Because the cavity length variation range of the dielectric cavity between the second reflection point 4 and the conductor reflection surface 11 is limited, when the sensor is designed, the larger the measurement range of the displacement sensor is, the smaller the ratio of Na to ML is; the displacement variation is always proportional to the cavity length variation of the dielectric cavity.

4) Displacement sensor for displacement reduction based on gear

The mechanical structure of the displacement sensor based on gear displacement reduction comprises various combinations of gears, including different types of gears or double-layer gears, racks, worms and other members, and the larger displacement is shifted and reduced through a series of gears, racks, worms and other members, so that the cavity length of the dielectric cavity 12 between the second reflection point 4 and the conductor reflection surface 11 is changed slightly, and the change amount is delta d, namely the cavity length change amount of the dielectric cavity is delta d. The displacement variation and Δ d are always proportional. The end faces of the housing and the inner rod conductor region of the dielectric cavity length measuring device are on a section plane, i.e. the plane on which the second reflection point 4 is located, and the plane is parallel to the conductor reflection surface 11, i.e. the axis of the cavity length measuring device is perpendicular to the conductor reflection surface 11.

Fig. 20(c) is a schematic structural diagram of a displacement sensor for performing displacement reduction based on a double-layer gear according to an embodiment of the present application. The displacement sensor probe 102 can move left and right without shaking by the linear motion bearing 109 fixed to the housing 1. The end face of the probe rod 102 of the displacement sensor is provided with a first rack 103, when the displacement changes, the first rack 103 is driven to move, the rack 103 is butted with a large-diameter gear on a double-layer gear 104, a small-diameter gear on the double-layer gear is butted with a second rack 107, the end face of the rack is fixed with a carrier 15 of a conductor reflecting surface 11, the left end face of the carrier is the conductor reflecting surface 11, the normal line of the conductor reflecting surface 11 is parallel to the axial lines of the shell 1 and the inner rod 2 of the cavity length measuring device, and the shell 1 of the cavity length measuring device, the rotating shaft 106 of the double-layer gear and the linear motion bearing 84 are all fixed on a substrate 116. When the displacement is changed greatly, the double-layer gear is used for carrying out displacement reduction, so that the rack with the conductor reflecting surface is changed in a small displacement mode, namely the cavity length of the dielectric cavity 12 between the second reflecting point 4 and the conductor reflecting surface 11 is changed in a small mode, and the change amount is delta d. The cavity length variation Δ d of the dielectric cavity 12 between the second reflection point and the conductor reflection surface can be determined by the variation of the resonant frequency/the cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity. Through calibration, a linear relation between the displacement variation and the delta d can be obtained. If the measuring range of the displacement sensor is large, the displacement is not reduced enough by one double-layer gear, and the displacement can be reduced by combining a plurality of double-layer gears.

Fig. 20(d) is a schematic structural view of a displacement sensor for performing displacement reduction based on the worm 113 according to the embodiment of the present application. The displacement sensor probe 102 is provided with a first rack 103, when the displacement changes, the first rack 103 is driven to move, the first rack 103 is butted with a first gear 112 with a worm 113, namely, one gear 112 and one worm 113 share a rotating shaft 111, and the gear rotates to drive the worm to rotate. The worm 113 abuts against the second gear 110, and at this time, a larger displacement is reduced by the worm, so as to drive the second gear 110 to rotate slightly. The second gear 110 is butted with a second rack 107, the end surface of the second rack is a carrier 15 of a conductor reflecting surface, the left end surface of the carrier 15 is a conductor reflecting surface 11, the axis of the conductor reflecting surface 11 is parallel to the axes of the cavity length measuring device shell 1 and the inner rod 2, and the shell 1 of the cavity length measuring device, the rotating shaft of the gear 106, the rotating shaft 111 of the worm 113, the bearing 114 for fixing the rotating shaft 111 and the two linear motion bearings 84 are all fixed on a base plate 116. The cavity length variation Δ d of the dielectric cavity 12 between the second reflection point 4 and the conductor reflection surface 11 can be determined by the variation of the resonant frequency/the cavity length of the open-core coaxial cable-fabry-perot resonator. By calibration, a linear relationship between the displacement variation w and the cavity length variation Δ d of the dielectric cavity can be obtained.

Example ten: sensor based on measuring refractive index

Fig. 21 is a schematic structural diagram of a sensor for measuring refractive index or corrosion according to an embodiment of the present application. The two principles are the same, and under the condition that the distance between the second reflection point and the conductor emission surface is not changed, namely the cavity length of the dielectric cavity is not changed, the parameters are reflected by measuring the refractive index of a substance filled in the dielectric cavity between the second reflection point and the conductor reflection surface.

1) Sensor for measuring refractive index

In the first refractive index sensor, a shell 1 and an inner rod 2 of a cavity length measuring device of a dielectric cavity are arranged on the left, a conductor reflecting surface 11 is arranged on the right, the right end face of an inner rod conductor region of each cavity length measuring device is used as a second reflecting point 4, the end face 4 of the inner rod conductor region is not in contact with the conductor reflecting surface 11, or is connected by an insulator, or is connected by a conductor with the resistivity more than or equal to a preset threshold value, namely, no conductor with the resistivity less than the preset threshold value exists in the dielectric cavity; the end face of the conductor region of the shell 1 and the end face of the inner rod can be the same plane, and can also be on the right side of the end face of the inner rod, and at the moment, the shell and the conductor reflection surface can be connected through a conductor, an insulator or not. The conductor reflecting surface 11 is at the right end of the second reflecting point 4, the plane in which the second reflecting point 4 is located is parallel to the conductor reflecting surface 11, and the geometrical distance d between the second reflecting point 4 and the conductor reflecting surface 11, i.e. the geometrical cavity length d of the dielectric cavity 12, is constant. A sealing structure 116 is arranged between the outer shell 1 and the inner rod 2 at the left end of the second reflection point 4, so that liquid, solid or gas with the refractive index to be measured is filled between the plane of the second reflection point 4 and the conductor reflection surface 11. Due to the fact that the refractive indexes of the fillers in the dielectric cavity are different, the measured actual cavity length of the dielectric cavity is changed before and after the fillers are placed, and the cavity length d' is related to the refractive index, so that the resonant frequency/the cavity length of the resonant cavity of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed. The distance d ' between the second reflection point and the conductor reflection surface can be determined by the resonance frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, namely after the filling material is placed, the cavity length of the dielectric cavity is d ', and the refractive index of the filled liquid or solid or gas can be obtained by the ratio of d to d '. For the convenience of measurement, the housing 1 and the conductor reflecting surface 11 can be partially connected, and the structure of the conductor reflecting surface 11 at least comprises a porous structure, so that liquid or gas can be conveniently infiltrated into the cavity of the dielectric cavity, and the refractive index can be measured.

The shell and the inner rod are arranged on the left side, the conductor region of the inner rod is connected with the conductor reflecting surface 11, the end face of the conductor region of the shell is arranged on the left side of the end face of the inner rod, namely on the left side of the conductor reflecting surface 11, and the right end face of the conductor region of the shell 1 of each sensor is used as a second reflecting point 4; the end face 4 of the shell conductor region and the conductor reflection face 11 are connected with each other without contact or with an insulator or with a conductor having a resistivity equal to or higher than a predetermined threshold value. The conductor reflecting surface 11 is at the right end of the second reflecting point 4, the plane in which the second reflecting point 4 is located is parallel to the conductor reflecting surface 11, and the geometrical distance d between the second reflecting point 4 and the conductor reflecting surface 11, i.e. the geometrical cavity length d of the dielectric cavity 12, is constant. A sealing structure 116 is arranged between the outer shell 1 and the inner rod 2 in the area of the left end of the second reflection point 4, so that liquid, solid or gas with the refractive index to be measured is filled between the plane of the second reflection point and the conductor reflection surface. The geometric cavity length d of the dielectric cavity 12 is constant, and after the filling material is placed, the cavity length of the dielectric cavity is measured to be d ', and the refractive index of the filled liquid or solid or gas can be obtained by the ratio of d to d'.

2) Sensor for measuring corrosion

The first condition is corrosion of the reflective surface of the conductor. The sensor for measuring corrosion has the same structure as the sensor for measuring refractive index, and the distance d between the second reflection point 4 and the reflecting surface 11 of the conductor remains constant, i.e. the geometric cavity length d of the dielectric cavity 12 is constant. The dielectric cavity 12 between the second reflection point 4 and the conductor reflection surface 11 is a cavity, and the carrier 15 of the conductor reflection surface 11 can be solid or made into a pore structure, so that the corrosion area is enlarged, and the sensitivity of the sensor is increased. The material of the reflective surface 11 is selected to be corrosive, such as construction steel. The housing 1 and the conductor reflecting surface 11 are also connected by a partial connection or a pore structure, so that liquid or gas can be easily immersed in the dielectric cavity. After the material of the conductor reflecting surface 11 is corroded, corrosion products, such as rust, are generated, so that the refractive index of the dielectric medium in the cavity 12 between the second reflecting point 4 and the conductor reflecting surface 11 is changed, and the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-fabry-perot resonant cavity is changed. According to the variation of the resonant frequency/the resonant cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity, the variation of the cavity length of the dielectric cavity can be measured, and the variation of the refractive index can be obtained, so that the corrosion degree can be determined.

The second condition is that the reflective surface of the conductor is not corroded. When the carrier 15 of the conductive reflector 11 is not corroded, it is ensured that external corrosion products can penetrate into the dielectric cavity region between the housing 1 and the conductive reflector 11. The conductor reflecting surface 11 may be formed in a porous structure, or the housing 1 and the conductor reflecting surface 11 may be connected to each other partially or through a porous structure. When corrosion products enter the dielectric cavity 12 between the housing 1 and the reflecting surface 11 of the conductor, the refractive index of this region changes, thereby changing the resonant frequency/cavity length of the open core coax fabry-perot cavity. The variation of the refractive index can be measured by the variation of the resonant frequency/the cavity length of the resonant cavity and the size of the geometric cavity length d of the dielectric cavity, so that the degree of corrosion can be determined.

Claims

1. A cavity length measuring device of a dielectric cavity, the cavity length measuring device comprising: a sensor, a demodulation device; wherein,

2. The dielectric cavity length measuring device of claim 1, wherein the sensor further comprises a housing, or a housing plus an inner rod, the housing being an outer conductor of the sensor, the inner rod being an inner conductor of the sensor; wherein,

3. A cavity length measuring device of a dielectric cavity according to claim 1, wherein the cavity length measuring device is a reflective cavity length measuring device in which:

4. A cavity length measuring device of a dielectric cavity according to claim 1, wherein the cavity length measuring device is a transmission type cavity length measuring device in which:

5. The dielectric cavity length measuring device of claim 4, wherein when the cavity length measuring device is a transmissive cavity length measuring device, the cavity length measuring device has at least the following modes: a positive feedback loop mode, a loop-free mode; wherein,

6. The dielectric cavity length measurement device of claim 5, wherein the positive feedback loop mode comprises: a microwave positive feedback loop and a positive feedback loop based on a photoelectric oscillator; wherein,

7. The dielectric cavity length measuring device according to any one of claims 1 to 6, wherein the sensor has therein: the shell or the shell is provided with an inner rod and a conductor reflecting surface; wherein the housing is formed of a continuous conductor, the inner rod is formed of a continuous conductor, the conductor reflecting surface is formed of a continuous conductor, and the continuous conductor is: a single conductive part, or a plurality of conductive parts connected together, or a conductor plating on an insulator, the conductive part being made of a conductive material at least comprising: metal, non-metal; the non-metals include at least: graphite, or carbon fiber, or conductive ceramics;

8. The dielectric cavity length measuring device of claim 7, wherein the cross-section of the housing is a closed shape or a non-closed shape;

in the case of the sensor comprising a housing plus an inner rod:

9. The cavity length measuring device of a dielectric cavity according to claim 7,

in the open type hollow coaxial cable-Fabry-Perot resonant cavity between the first reflection point and the second reflection point and between the outer shell and the inner rod, a filled medium is one of the following media: vacuum, gas, liquid, solid;

10. The dielectric cavity length measuring device of claim 7, wherein the first reflection point and the second reflection point are disposed between the outer shell and the inner rod; the second reflection point is an end face of the outer shell or the inner rod; or when the outer shell and the inner rod are not in contact with the conductor reflecting surface and the lengths of the outer shell and the inner rod are different, the second reflecting point is between the end surface of the outer shell and the end surface of the inner rod; wherein,

11. A cavity length measuring device of a dielectric cavity according to claim 3, wherein in the reflection type cavity length measuring device:

12. A cavity length measuring device of a dielectric cavity according to claim 4 or 5, wherein in the transmission type cavity length measuring device, the cavity length measuring device has at least the following mode: positive feedback loop mode, loop-free mode:

13. The cavity length measuring device of a dielectric cavity according to claim 7,

the first reflection point is a conductor and is connected with the inner rod and the outer shell, so that the inner rod and the outer shell are short-circuited; the second reflection point is the end surface of the outer shell or the inner rod;

14. The cavity length measuring device of a dielectric cavity according to claim 7,

the reflectivity is adjusted by changing the shape and the size of the section of the inner rod, a first reflection point added between the shell and the inner rod can be removed, and the joint of the radio frequency coaxial cable adapter and the shell as well as the inner rod is used as the first reflection point; when the radio frequency coaxial cable adapter is taken as a first reflection point at the joint of the outer shell and the inner rod, the ratio of the diameter of the inner rod to the inner diameter of the outer shell is between 0 and 1; or,

15. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a pressure sensor;

16. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a pressure sensor;

17. The dielectric cavity length measuring device according to any one of claims 2 to 6, wherein the cavity length measuring device is applied in an acceleration sensor;

18. The dielectric cavity length measuring device of claim 7, wherein the cavity length measuring device is applied to a flow rate sensor, the flow rate sensor being a first flow rate sensor or a second flow rate sensor;

19. The dielectric cavity length measuring device of claim 15, wherein the cavity length measuring device is applied to a flow rate sensor, the flow rate sensor being a first flow rate sensor or a second flow rate sensor;

20. A dielectric chamber length measuring device according to any of claims 2 to 6, wherein the chamber length measuring device is used in a force gauge, the force gauge being a first type force gauge or a second type force gauge;

21. The cavity length measuring device of the dielectric cavity according to any one of claims 2 to 6, wherein the cavity length measuring device is applied in a strain gauge;

22. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a unidirectional inclinometer; a cavity length measuring device for measuring the dielectric cavity is adopted to be made into a one-way inclinometer;

23. The dielectric cavity length measuring device of claim 22, wherein the cavity length measuring device is used in a bi-directional inclinometer;

the first working condition is as follows: connecting a top plate and a heavy object by using parallel and equal-length flexible ropes or elastic rods hinged at two ends, fixing the inclinometer on a measured object, and using three parallel and equal-length flexible ropes or elastic rods hinged at two ends, namely three flexible ropes or elastic rods hinged at two ends respectively form two triangles with three points connected with the top plate and the heavy object, wherein the length of the flexible ropes or the elastic rods hinged at two ends is L; when the three flexible ropes or the three intersection points of the elastic rods hinged at the two ends and the top plate are not on the same straight line, the two inclination directions are respectively inclined around an X axis and inclined around a Y axis; a weight is hung below the three ropes, and the normals of two surfaces serving as conductor reflecting surfaces are respectively an X axis and a Y axis; the axes of the cavity length measuring devices of the two dielectric cavities are respectively vertical to the two conductor reflecting surfaces, and the end surfaces of the shells and the inner rod of the two cavity length measuring devices keep a certain distance from the two conductor reflecting surfaces; when the inclinometer is around the X axis and the Y axisAfter the two cavity length measuring devices are inclined, the distance between the second reflecting point of the two cavity length measuring devices and the conductor reflecting surface is changed, so that the resonant frequency/the cavity length of the open type hollow coaxial cable-Fabry-Perot resonant cavity is changed, and the distance variation between the second reflecting point of the two cavity length measuring devices and the conductor reflecting surface can be calculated, namely the cavity length variation of the dielectric cavity is respectively delta d₁And Δ d₂(ii) a The distance between the second reflection point of the first cavity length measuring device and the conductor reflection surface changes by delta d₁And the length L of the rope, the variation delta theta of the inclination angle of the inclinometer around the X axis can be determined₁＝arcsin(Δd₁L); the cavity length variation deltad of the dielectric cavity between the second reflection point of the second cavity length measuring device and the conductor reflection surface₂And the length L of the rope, the variation delta theta of the inclination angle of the inclinometer around the Y axis can be determined₂＝arcsin(Δd₂L); as long as the number of the flexible ropes or the elastic rods hinged at the two ends is more than or equal to 3, all the flexible ropes or the elastic rods hinged at the two ends are equal in length and are arranged in parallel, and the connecting lines of the fixed points of all the flexible ropes or the elastic rods hinged at the two ends and the top plate are not in the same straight line, the inclination angles in two directions can be obtained by using the working condition calculation method; when three or more elastic rods which are not in a straight line with the fixed point of the top plate and are parallel and equal in length are used for connecting the top plate and the heavy object in a hinged mode, the calculation method is the same as that under the first working condition;

the second working condition is as follows: the top plate and the heavy object are rigidly connected by using an elastic rod, the inclinometer is fixed on the measured object by using one elastic rod, or two elastic rods, or more than three elastic rods, the length of each elastic rod is L, and the elastic rods are rigidly connected with the top plate and the heavy object; when the inclinometer inclines around the X axis and the Y axis, the distance variation between the second reflecting point and the conductor reflecting surface can be obtained through the resonance frequency/resonant cavity length variation of the two cavity length measuring devices, namely the cavity length variation of the dielectric cavity is delta d₁And Δ d₂The cavity length variation delta d of the two dielectric cavities needs to be obtained through calibration₁、Δd₂And the inclination angle variation amount delta theta₁、Δθ₂Is close toIs described.

24. The dielectric cavity length measuring device of claim 15, wherein the cavity length measuring device is used in a unidirectional inclinometer;

When the tops of the two left and right pressure sensors are connected to a top plate in the container through flexible ropes or elastic rods with two hinged ends, the distance between the two fixed points is d, and the axes of the two pressure sensors are always vertical and do not rotate along with the inclination of a measured object under the action of gravity; the end surfaces of the outer shell and the inner rod are arranged below the outer shell, and the two pressure measuring diaphragms or Bourdon tube end diaphragms are immersed in liquid and are equal to the bottom of the container; when the object to be tested drives the closed container to twoWhen the inclination occurs in the plane formed by the axes of the pressure sensors, the depth of the two pressure sensors immersed in the liquid also changes, so that the pressure measured by the two pressure sensors also changes, and the variation delta L of the immersion depth is obtained through the variation of the pressure of the two pressure sensors₁And Δ L₂Finally, the degree change amount of the inclination angle is Δ θ ═ arcsin [ (Δ L)₂-ΔL₁)/d]。

25. The dielectric cavity length measuring device of claim 16, wherein the cavity length measuring device is used in a unidirectional inclinometer;

When the tops of two left and right pressure sensors are flexibly arrangedWhen the rope or the elastic rod with two hinged ends is connected to the top plate in the container, the distance between the two fixed points is d, and under the action of gravity, the axes of the two pressure sensors are always vertical and do not rotate along with the inclination of the measured object; the end surfaces of the outer shell and the inner rod are arranged below the outer shell, and the two pressure measuring diaphragms or Bourdon tube end diaphragms are immersed in liquid and are equal to the bottom of the container; when the object to be measured drives the closed container to incline in a plane formed by the axes of the two pressure sensors, the depth of the two pressure sensors immersed in the liquid also changes, so that the pressure measured by the two pressure sensors also changes, and the variation delta L of the immersion depth is calculated according to the variation of the pressure of the two pressure sensors₁And Δ L₂Finally, the degree change amount of the inclination angle is Δ θ ═ arcsin [ (Δ L)₂-ΔL₁)/d]。

26. The dielectric cavity length measuring device of claim 15, wherein the cavity length measuring device is used in a bi-directional inclinometer;

when the three pressure sensors are rigidly fixed inside the container, the three pressure sensors rotate along with the inclination of the measured object; the three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the pressure measuring diaphragms or Bourdon tube end face diaphragms of the three pressure sensors are immersed in the liquid and are equal to the bottom of the container; when three intersection points of the axes of the three pressure sensors and the horizontal plane form a right triangle, two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁On an axis between the second pressure sensor and the third pressure sensorParallel spacing of d₂(ii) a When the inclinometer inclines around the X axis and the Y axis, the depth of the first pressure sensor and the second pressure sensor immersed in the liquid changes, so that the pressures measured by the two pressure sensors change, and the variation delta L of the immersion depth is calculated according to the pressure variation of the two pressure sensors₁And Δ L₂According to the parallel spacing d₁Can determine the variation of the inclination angle of the inclinometer around the X axis as delta theta₁＝arctan[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the variation of the inclination angle of the inclinometer around the Y axis as delta theta₂＝arctan[(ΔL₃-ΔL₂)/d₂]；

When the tops of the three pressure sensors are connected to a top plate in the container through flexible ropes or elastic rods hinged to two ends of the three pressure sensors, under the action of gravity, the axes of the three pressure sensors are always vertical and do not rotate along with the inclination of a measured object; the three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the pressure measuring diaphragms or Bourdon tube end face diaphragms of the three pressure sensors are immersed in the liquid and are equal to the bottom of the container; when the three intersection points of the axes of the three pressure sensors and the top plate form a right triangle, the two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a When the inclinometer is inclined around the X axis and the Y axis, the depth of the first pressure sensor and the second pressure sensor which are immersed in the liquid changes, so that the pressures measured by the two pressure sensors change, and the pressures measured by the two pressure sensors changeDetermining the amount of change Δ L of immersion depth₁And Δ L₂According to the parallel spacing d₁Can determine the variation delta theta of the inclination angle of the inclinometer around the X axis₁＝arcsin[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the inclination angle variation delta theta of the inclinometer around the Y axis₂＝arcsin[(ΔL₃-ΔL₂)/d₂]。

27. The dielectric cavity length measuring device of claim 16, wherein the cavity length measuring device is used in a bi-directional inclinometer;

when the three pressure sensors are rigidly fixed inside the container, the three pressure sensors rotate along with the inclination of the measured object; the three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the pressure measuring diaphragms or Bourdon tube end face diaphragms of the three pressure sensors are immersed in the liquid and are equal to the bottom of the container; when three intersection points of the axes of the three pressure sensors and the horizontal plane form a right triangle, two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a When the inclinometer is tilted about both the X and Y axes,the depth of the first pressure sensor and the second pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₁And Δ L₂According to the parallel spacing d₁Can determine the variation of the inclination angle of the inclinometer around the X axis as delta theta₁＝arctan[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the variation of the inclination angle of the inclinometer around the Y axis as delta theta₂＝arctan[(ΔL₃-ΔL₂)/d₂]；

When the tops of the three pressure sensors are connected to a top plate in the container through flexible ropes or elastic rods hinged to two ends of the three pressure sensors, under the action of gravity, the axes of the three pressure sensors are always vertical and do not rotate along with the inclination of a measured object; the three intersection points of the axes of the three pressure sensors and the horizontal plane are not on the same straight line; the bottom of the closed container is filled with liquid, and the pressure measuring diaphragms or Bourdon tube end face diaphragms of the three pressure sensors are immersed in the liquid and are equal to the bottom of the container; when the three intersection points of the axes of the three pressure sensors and the top plate form a right triangle, the two right-angle sides are respectively an X axis and a Y axis in the inclined direction; the parallel distance between the axes of the first pressure sensor and the second pressure sensor is d₁And the parallel distance of the axes between the second pressure sensor and the third pressure sensor is d₂(ii) a When the inclinometer inclines around the X axis and the Y axis, the depth of the first pressure sensor and the second pressure sensor immersed in the liquid changes, so that the pressures measured by the two pressure sensors change, and the variation delta L of the immersion depth is calculated according to the pressure variation of the two pressure sensors₁And Δ L₂Then according toParallel spacing d₁Can determine the variation delta theta of the inclination angle of the inclinometer around the X axis₁＝arcsin[(ΔL₂-ΔL₁)/d₁](ii) a The depth of the second pressure sensor and the third pressure sensor immersed in the liquid is changed, so that the pressures measured by the two pressure sensors are also changed, and the variation Delta L of the immersion depth is calculated according to the variation of the pressures of the two pressure sensors₂And Δ L₃According to the parallel spacing d₂Can determine the inclination angle variation delta theta of the inclinometer around the Y axis₂＝arcsin[(ΔL₃-ΔL₂)/d₂]。

28. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a slip meter;

the slippage meter carrier is fixed on the medium A, the shell of the first cavity length measuring device is fixed in the first inclined hole of the slippage meter carrier, and the second cavity length measuring deviceThe shell of the sliding meter is fixed in a second inclined hole of the sliding meter carrier, the end surfaces of the shell of the first cavity length measuring device and the inner rod are opposite and parallel to a first inclined surface, the end surfaces of the shell of the second cavity length measuring device and the inner rod are opposite and parallel to a second inclined surface, the first inclined surface and the second inclined surface are two inclined surfaces of a double-inclined-surface carrier, and the double-inclined-surface carrier is fixed on a medium B; a second-order matrix formed by normal vectors of the two inclined planes

29. the dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a slip meter;

Is equal to 3, whereThe normal vector of the first inclined plane is (l)₁,m₁,n₁)^TThe normal vector of the second inclined plane is (l)₂,m₂,n₂)^TThe normal vector of the third inclined plane is (l)₃,m₃,n₃)^TThe inclination angle theta of the three inclined planes relative to the horizontal plane₁、θ₂And theta₃Between-90 ° and 90 °;

30. the cavity length measuring device of a dielectric cavity according to any of claims 2 to 6, wherein the cavity length measuring device is applied in a spring and diaphragm based displacement sensor;

31. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a displacement sensor based on a slope structure;

32. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a displacement sensor based on a folded lever structure;

33. The dielectric cavity length measuring device of any one of claims 2 to 6, wherein the cavity length measuring device is applied in a displacement sensor based on a gear and rack structure;

34. The cavity length measuring device of the dielectric cavity according to any one of claims 2 to 6, wherein the cavity length measuring device is applied to a refractive index sensor, the refractive index sensor being a first type of refractive index sensor or a second type of refractive index sensor;

35. The dielectric cavity length measuring device of claim 34, wherein the cavity length measuring device is used in a sensor for measuring corrosion; the sensor for measuring corrosion has the following two conditions: