WO2019028945A1

WO2019028945A1 - Pressure sensor

Info

Publication number: WO2019028945A1
Application number: PCT/CN2017/099330
Authority: WO
Inventors: 陈艺征; 黄捷; 唐艳; 陈昌林
Original assignee: 江苏弘开传感科技有限公司
Priority date: 2017-08-08
Filing date: 2017-08-28
Publication date: 2019-02-14
Also published as: CN109387309A

Abstract

A pressure sensor, comprising: a displacement sensor (40), an elbow pipe (30) and a base (32); a first end of the elbow pipe (30) is fixed on the base (32), the displacement sensor (40) comprises a first reflection member (50) and a second reflection member (51), the first reflection member (50) being fixed in the main body of the displacement sensor (40), and the second reflection member (51) being movable relative to the main body of the displacement sensor (40); the main body of the displacement sensor (40) is fixed on the base (32), and the second reflection member (51) is connected to the elbow pipe (30) at a first position of the elbow pipe (30); alternatively, the second reflection member (51) is fixed on the base (32), and the main body of the displacement sensor (40) is connected to the elbow pipe (30) at a first position of the elbow pipe (30); when the pressure in the elbow pipe (30) changes, the elbow pipe (30) deforms, such that the distance between the first reflection member (50) and the second reflection member (51) changes, and the magnitude of the change of pressure is obtained by means of the displacement measured by the displacement sensor (40).

Description

Pressure sensor

Cross-reference to related applications

The present application is filed on the basis of the Chinese Patent Application No. PCT Application No.

Technical field

The present invention relates to measurement techniques, and more particularly to a pressure sensor.

Background technique

At present, pressure sensors are mostly based on measuring the deformation of the diaphragm to calculate the pressure. Specifically, the end of the pressure sensor is a pressurized diaphragm, and the fiber grating (FBG) strain gauge is strained by compressing the diaphragm and burying the material embedded in the FBG, and calculating the pressure by the strain size. The extrinsic Fabry Perot interferometer (EFPI) sensor is the end of the fiber opposite the pressurized diaphragm, the end of the fiber is the first reflection point, and the center of the diaphragm is the second end of the fiber. At the point of reflection, the deformation of the diaphragm causes a change in the deflection of the center point, resulting in a change in the length of the cavity. The vibrating wire sensor is similar to the FBG. One end of the vibrating wire is followed by one end of the diaphragm of the sensor, and the other end of the vibrating wire is followed by one end of the diaphragm. After the diaphragm is deformed, the distance between the two fixed points changes, causing the vibration frequency of the vibrating wire to change, and the pressure is calculated accordingly.

The current pressure sensors have the common feature that the pressure is measured based on the tiny deformation of the diaphragm, that is, the sensors are strain-based sensors, which are subject to temperature and require temperature compensation, even if In this way, the measurement accuracy of the pressure is also affected, and if the number of times of material deformation is too large, fatigue will occur and permanent drift will occur.

Summary of the invention

In order to solve the above technical problem, an embodiment of the present invention provides a pressure sensor, which is a sensor that reflects a pressure based on measuring deflection of a bend.

The pressure sensor provided by the embodiment of the present invention includes: a displacement sensor, an elbow, and a base; the first end of the elbow is fixed on the base, wherein

The displacement sensor includes a first reflective member, a second reflective member fixed in a body of the displacement sensor, the second reflective member being movable relative to a body of the displacement sensor;

a body of the displacement sensor is fixed on the base, the second reflection member is connected to the elbow at a first position of the elbow; or the second reflection member is fixed on the base The body of the displacement sensor is coupled to the elbow at a first position of the elbow;

When the pressure in the elbow changes, the elbow deforms and drives a reflective member to move, causing a change in the distance between the first reflective member and the second reflective member, through the displacement sensor The magnitude of the measured displacement gives the magnitude of the pressure change.

In the embodiment of the present invention, the displacement sensor is a displacement sensor of a cavity length measuring device based on a microwave resonant cavity, and the cavity length measuring device is a reflective cavity length measuring device or a second transmissive cavity length measuring device, wherein The two reflective components of the displacement sensor refer to two reflection points whose reflectance is greater than or equal to a threshold.

In an embodiment of the invention, the second reflection point of the displacement sensor is connected to the probe:

The displacement sensor is fixed on the base by a part of the base for fixing the displacement sensor;

The probe end of the displacement sensor is fixedly integrated with the baffle, and the baffle is fixed at the first position of the elbow, wherein the first position is an apex or an end point of the elbow;

After the bending tube is deformed by the pressure, the fixing point of the bending tube for fixing the baffle moves relative to the base, thereby driving the end of the probe of the displacement sensor to move, Calculating the magnitude of the movement of the end of the probe measured by the displacement sensor; or

The probe end of the displacement sensor is fixed at a first position of the elbow by a linkage member, wherein the first position is a point on the elbow, and a point on the elbow includes at least a vertice or an end point; after the bending tube is deformed by the pressure, the linking component on the elbow drives the end of the probe to move, thereby driving the second reflecting point to move, and measuring by the displacement sensor The amount of movement of the second reflection point obtained is obtained by the magnitude of the pressure.

In the embodiment of the present invention, the end of the probe of the displacement sensor and the baffle are integrally fixed to:

The probe end of the displacement sensor is directly mounted on the baffle; or

The probe end of the displacement sensor is connected to the baffle by a connecting part, wherein the connecting part is a just-connected part or a hinged part.

The probe of the displacement sensor is fixed on the base by a part protruding from the base for fixing the probe;

The end of the displacement sensor is fixedly integrated with the baffle, and the baffle is fixed at the first position of the elbow, wherein the first position is an apex or an end point of the elbow;

After the bending tube is deformed by the pressure, the fixing point of the bending tube for fixing the baffle moves relative to the base, thereby driving the end of the displacement sensor to move, and measuring by the displacement sensor The resulting movement of the probe is given a magnitude of pressure.

In an embodiment of the invention, the first reflection point of the displacement sensor is fixed to the first section of the outer casing and the inner rod, and the second reflection point of the displacement sensor is fixed to the outer casing and the second section of the inner rod, the outer casing and The inner rod is of a structure capable of being stretched or compressed and maintaining electrical continuity, the structure capable of stretching or compressing and maintaining electrical continuity: the first and second sections of the outer and inner rods The structure may be connected by a nested structure, or a spring structure, or a bellows structure; the second section of the displacement sensor is integrally formed as a probe, wherein the outer portion at the first reflection point a structure of the outer fixing protrusion of the outer casing as a first fixing point, and a structure of fixing the outer surface of the outer casing at the second reflection point as a second fixing point;

In the embodiment of the present invention, one end of the displacement sensor resonant cavity is connected to the RF coaxial cable adapter, and the other end may be open, may be sealed, or may be connected to a coaxial cable adapter and the same The shaft cable adapter is in contact with the outer casing and the inner rod. Taking the movement of the second reflection point as an example, the reflection point moves by one end of one part to the second reflection point, and the other end extends beyond the outer casing, and the movement of the reflection point is driven by pulling the movement of the part. Since the part and the second reflection point are connected integrally, the part and the second reflection point are connected to a part of the outer casing during the movement, and need to be grooved on the outer surface of the outer casing to facilitate the part and the reflection point. Moving without affecting the conductive continuity of the outer casing;

The first fixing point is fixed on the base;

The second fixing point is directly fixed at the first position of the elbow; or the second fixing point is fixed to the baffle by a hinge part, the baffle being fixed at the first position of the elbow Where the first position is a vertex or an end point of the elbow.

In the embodiment of the present invention, the elbow is a spiral tube, and an axis of the displacement sensor coincides with an axis of the spiral tube, wherein the movement of the probe of the displacement sensor after the bending tube is deformed due to pressure The direction coincides with the axial direction of the displacement sensor.

In the embodiment of the present invention, the first end of the elbow is a closed structure, and the second end is a non-closed structure; or the first end of the elbow is a closed structure, after the elbow is filled with liquid The second end of the elbow is sealed by a diaphragm that is deformable when pressed to squeeze liquid within the elbow.

In the embodiment of the present invention, the displacement sensor is a displacement sensor of a cavity length measuring device based on a microwave resonant cavity, and at least one reflection point uses an elbow inside the outer casing, and the cavity length measuring device is a reflective cavity length measurement. a device, or a first transmissive cavity length measuring device, or a second transmissive cavity length measuring device, wherein:

The first reflecting member of the displacement sensor is a first reflecting point fixed in a range of an outer casing and an inner rod envelope, and the second reflecting member of the displacement sensor is fixed to the outer casing and at least a part is in the outer casing and a bent pipe within the inner rod envelope; or,

The first reflecting member of the displacement sensor is the elbow fixed to the outer casing and at least a part of which is within the outer casing and the inner rod envelope, and the second reflecting member of the displacement sensor is a fixed outer casing and an inner rod package The first reflection point within the range; or,

The first reflective component of the displacement sensor is fixed to the outer casing and at least a portion is a first elbow within the outer casing and the inner rod envelope, and the second reflective component of the displacement sensor is fixed on the outer casing and at least A portion is a second elbow in the outer casing and the inner rod envelope, the first elbow and the second elbow are oppositely mounted, and the two elbows as reflection points are changed when the external pressure is changed Can move in the opposite direction.

In the embodiment of the present invention, the first end of the elbow is a closed structure, and the second end of the elbow is connected to a gas or a liquid with a pressure outside the tube; or the first end of the elbow is a closed structure, the second end of the elbow is provided with a membrane through which the membrane is in contact with a gas or liquid with pressure, wherein the elbow is a liquid or a gas;

After the elbow is deformed by water pressure or air pressure, each point of the elbow can be moved, and the magnitude of the movement of the measuring point on the elbow is measured by the displacement sensor to obtain a pressure.

In the embodiment of the present invention, the displacement sensor is a displacement sensor based on an extrinsic Fabry-Perot interferometer (EFPI). In the extrinsic Fabry Perot interferometer, the first reflective surface refers to The fiber end face and the second reflecting surface are mirrors.

In the embodiment of the present invention, the optical fiber including the first reflective surface is fixed on the base by a component for fixing the optical fiber protruding from the base;

The mirror including the second reflecting surface is fixed at a first position of the elbow by a connecting part, wherein the first position is an apex or an end point of the elbow or other opposite base on the elbow can occur Moving point

The connecting part comprises a clamp fixed to the elbow and a part fixing the mirror, wherein the clamp on the fixed elbow is fixed to the elbow, and the part of the fixed mirror is fixed on the fixed to the elbow On the fixture, the part of the fixed mirror and the fixture fixed to the elbow can be connected by a rigid joint or a hinged part; wherein an axis of the end of the optical fiber is perpendicular to the second reflective surface;

After the bending tube is deformed by the pressure, the connecting component drives the second reflecting surface to move relative to the first reflecting surface, and is measured by the extrinsic Fabry Perot interferometer (EFPI) displacement sensor. The amount of change in the cavity length between the first reflecting surface and the second reflecting surface obtained is obtained by the pressure.

In the embodiment of the present invention, the displacement sensor is an optical distance finder-based displacement sensor. In the optical range finder, a fixed point for fixing the optical distance meter and a fixed point for fixing the reflector are bent. Relative movement can occur after the tube is deformed.

In the embodiment of the present invention, the optical range finder is fixed on the base by a part extending on the base for fixing the optical range finder;

The reflector is fixed at a first position of the elbow by a connecting part, wherein the first position is a point at which an apex or an end point of the elbow or other opposite base on the elbow can move;

The connecting part includes a fixing fixture and a reflector, wherein the fixing fixture is fixed to the reflector, the fixing fixture is fixed at a first position of the elbow, the fixing fixture and the reflector Connected by hinged parts;

After the bending tube is deformed by the pressure, the clamp fixed on the curved tube drives the reflector to move relative to the optical range finder, and the measured by the displacement sensor based on the optical range finder The change in the distance between the reflector and the optical rangefinder gives the magnitude of the pressure.

In the embodiment of the present invention, the elbow is a spiral tube, and an optical axis of the optical range finder overlaps with an axis of the spiral tube, wherein the deflecting plate moves after the bending tube is deformed due to pressure. The moving direction coincides with the axial direction of the spiral tube.

In the embodiment of the present invention, the shape of the elbow is non-linear, wherein the axis of the elbow is a curve or a broken line in a plane, or a curve in a space, and the curve in the space includes at least a spiral ;

The curved pipe has a closed shape, and the closed shape includes at least a circular ring, an elliptical ring, and a square hole shape, wherein each of the curved pipes has the same shape and/or size, or has a different shape. And / or size.

In the embodiment of the present invention, the displacement sensor further includes at least: an FBG displacement meter, or a vibrating wire type displacement meter, or a differential resistance type displacement meter, wherein the displacement sensor calculates the deflection by measuring the deflection of the elbow The pressure on the elbow.

In the technical solution of the embodiment of the present invention, the pressure sensor comprises: a displacement sensor, an elbow, a base; the first end of the elbow is fixed on the base, wherein the displacement sensor comprises a first reflective component and a second a reflecting member fixed in a body of the displacement sensor, the second reflecting member being movable relative to a body of the displacement sensor; a body of the displacement sensor being fixed on the base, a second reflecting member is coupled to the elbow at a first position of the elbow; or the second reflecting member is fixed to the base, the main body of the displacement sensor being at the first of the elbow a position is connected to the elbow; when the pressure changes, the elbow deforms and drives a reflective member to move, causing a change in a distance between the first reflective member and the second reflective member. The magnitude of the pressure change is obtained by the magnitude of the displacement measured by the displacement sensor. The technical solution of the embodiment of the invention has at least the following advantages: high measurement accuracy, high signal to noise ratio, and high cost performance of the device.

DRAWINGS

1 is a schematic structural diagram of a sensor based on a hollow coaxial cable-Fabrero resonator;

Figure 2 (a) shows a sensor based on a hollow coaxial cable - Fabry Perot cavity containing an inner rod Schematic;

2(b) is a schematic view showing the structure of a sensor based on a hollow coaxial cable-Fabrero cavity without an inner rod;

3 is a reflection and transmission amplitude spectrum of a sensor based on a hollow coaxial cable-Fabrero resonator;

Figure 4 is a cross-sectional view commonly used of the outer casing;

Figure 5 is a cross-sectional view commonly used for the inner rod;

Figure 6 is a cross-sectional view of a commonly used reflection point.

Figure 7 is a schematic view showing the connection of the outer casing to the outer casing or the inner rod and the inner rod after the outer casing or the inner rod is segmentally connected;

Figure 8 (a) is a schematic structural view of a displacement sensor based on a reflective hollow coaxial cable - Fabry Perot cavity;

8(b) is a schematic structural view of a displacement sensor based on a transmission structure of a hollow coaxial cable-Fabrero resonator and having a positive feedback loop;

Figure 8 (c) is a schematic structural view of a displacement sensor based on a transmission structure of a hollow coaxial cable - Fabry Perot cavity and without a loop;

Figure 8 (d) is a schematic structural view of a displacement sensor based on a special coaxial structure of a hollow coaxial cable - Fabry Perot cavity;

Figure 9 is a schematic view showing the structure of five curved tubes or Bourdon tubes;

Figure 10 is a schematic structural view of several methods of connecting the end of the displacement meter to the elbow;

Figure 11 is a schematic view showing the mounting method of the displacement gauge and the baffle mounted on the Bourdon tube;

Figure 12 is a schematic view showing the mounting method of the displacement gauge and the baffle mounted on the spiral tube;

Figure 13 (a) is a structural schematic view of a pressure sensor of a reflective hollow coaxial cable - Fabry Perot cavity of a curved tube as a second reflection point;

Figure 13 (b) shows the hollow coaxial cable - Fabry Perot resonance of the elbow as the second reflection point Schematic diagram of a first type of pressure sensor with a positive feedback loop and a positive feedback loop;

Figure 13 (c) is a schematic view showing the structure of a first transmission and loop-free pressure sensor of a hollow coaxial cable-Fabrero cavity of a curved tube as a second reflection point;

Figure 13 (d) is a structural schematic view of a second type of transmission of a hollow coaxial cable-Fabrero cavity with a positive feedback loop and a pressure feedback sensor with a positive feedback loop;

Figure 13 (e) is a schematic view showing the structure of a second transmission and loop-free pressure sensor of a hollow coaxial cable-Fabrero cavity as a second reflection point;

Figure 14 is a schematic view showing the installation method of the Fabry Perot principle fiber end face and the mirror mounted on the Bourdon tube;

Figure 15 is a schematic view showing an installation method of an optical range finder and a reflector mounted on a Bourdon tube;

Figure 16 is a schematic view showing the mounting method of the optical range finder and the reflector mounted on the spiral tube.

Description of the reference signs:

1- outer casing, which may be a hollow tube, rod, spring or other continuous conductor; 2-inner rod, which may be hollow, solid, or a continuous conductor of spring or other shape; 3-first reflection point, It is a conductor or an insulator, which may or may not be connected to the outer casing or the inner rod. It may be any shape or a combination of multiple parts; 4 - the second reflection point, the property is the same as the first reflection point; 5 - resonant cavity , internal can be gas or liquid; 6-coaxial cable adapter; 7-coaxial cable adapter center signal pin; 8-transmission coaxial cable; 9-vector analyzer or scalar microwave analysis Instrument; 10-directional coupler; 11-waveform amplifier; 12-counter; 13-coaxial cable adapter; 15--sealing 1 and inner rod 2 end sealing device, can be a conductor, can be an insulator, Can be closed or non-closed shape, can also be coaxial cable adapter; 16-left end tube or rod butt joint parts; 17-right end tube or rod butt joint parts; 18-conductor shaft; 19-conductor bellows, multi-purpose Metal; 20-moving parts, one end of the part To the reflection point, the other end extends beyond the outer casing, and moves the reflection point by pulling the movement of the part; 21-displacement gauge on the inner rod sleeve; 22-displacement gauge probe; 23-displacement gauge prevents the sleeve from shaking Device with anti-sway and sealing function; 24- Left end housing; 25-right end housing; 26-left end inner rod; 27-right end inner rod; 28-left end fixed point; 29-right end fixed point; 30-bend; 31-bend tube press port, can be a hole , may also be a pressurized diaphragm; 32-bend base; 33-part of the fixed sensor protruding from the base; 34-the first part of the hinge member, which may be the end of the displacement gauge probe, Can be a part of a fixed mirror or reflector; 35-clamp for fixing parts such as the mirror or the end of the displacement probe to the elbow; 36-transformed parts with hinges at both ends; 38-end fixed Rod end, the other end is a hinged part; 40 - displacement sensor based on the principle of hollow coaxial cable - Fabry Perot cavity; 41 - demodulation system; 42 - elbow as the second reflection point; - first reflecting surface, generally fiber end face; 51 - second reflecting surface, generally mirror; 52-transmission fiber; 53-fiber protective sleeve; 54-sealing plug; 55-pressure sensor housing; 60-optical ranging Instrument; 61-reflector; 62-transmission cable; 63-transmission cable cover.

Detailed ways

Embodiments of the present invention provide a novel cavity length measuring device for a microwave resonant cavity, wherein the microwave resonant cavity is specifically a hollow coaxial cable-Fabrero cavity, and the cavity length measuring device according to the embodiment of the present invention can The cavity length of the hollow coaxial cable-Fabbrero resonator is measured. The embodiment of the invention combines the cavity length measuring device and the auxiliary mechanical design, and can convert the cavity length measuring device into the following sensors: displacement sensor, (no resistance) strain sensor, slip sensor, angle sensor, load cell (also called Dynamometer), displacement sensor based on displacement reduction, liquid level sensor (also known as level gauge) and pressure sensor.

In the technical solution of the embodiment of the invention, the sensor can accurately measure the displacement, the strain, the slip amount, the angle, the force, the liquid level and the pressure based on different mechanical transmission modes, and the measurement principle is based on the hollow coaxial cable. - The principle of the Fabry Perot cavity, here, the hollow coaxial cable - Fabry Perot cavity includes: a housing, an inner rod (optional), a resonant cavity and two reflection points, resonance The structure of the cavity is convenient to manufacture, and the physical displacement such as displacement, strain, slip, angle, force and pressure under static force and dynamic force can be measured by the movement of the reflection point in the cavity. In addition, the temperature compensation of the sensor is very convenient and is not affected by electromagnetic factors. Most of the sensors of the present invention do not require temperature compensation. In the case of temperature compensation, temperature compensation can be performed by multiple reflection points or other principles of the thermometer, and common parameters such as displacement, strain, slip or angle can be monitored. . The sensor designed by the embodiment of the invention has the advantages of high precision, strong anti-interference ability and strong durability, and has wide application prospects, and is particularly suitable for high-precision measurement of mechanical properties and ambient temperature under static and dynamic structures. Due to the stable material properties of the sensor, it is easy to work between minus 60 degrees and a few hundred degrees above zero. By changing the material, it can work in a wider temperature range. In summary, the sensor of the embodiment of the present invention is not interfered by any electromagnetic signals, the temperature is extremely small, and temperature compensation is very easy to implement.

The hollow coaxial cable-Fabrero resonator in the embodiment of the present invention is similar to the conventional optical Fabry-Perot resonant cavity (FP cavity), and is different from the optical Fabry-Perot resonant cavity. The coaxial cable-Fabrero resonator is fabricated based on a radio frequency coaxial cable and is a microwave-based sensor.

In the embodiment of the present invention, the two reflection points are high reflection points, where the reflectance of the high reflection point is generally higher than 50%, and in a few cases less than 50%, but not lower than 20%, due to each reflection The point has a high reflectivity and is therefore not suitable for use as a distributed sensor. The Fabry Perot resonator is a resonance phenomenon caused by multi-channel interference, and has the characteristics of high demodulation precision, high signal-to-noise ratio, and high cost performance of the demodulation equipment.

In the embodiment of the present invention, a new self-processed hollow coaxial cable-Fabrero cavity platform is proposed, and the internal insulator of the hollow coaxial cable-Fabrero resonator is generally air, special It can be filled with liquid when applied.

The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

1 is a schematic view of a hollow coaxial cable-Fabrero resonator according to an embodiment of the present invention. A hollow coaxial cable - Fabry Perot resonator (ie microwave cavity) consists of a hollow coaxial cable - Fabry Perot cavity and two reflection points with high reflectivity (two reflection points) Divided into a first reflection point and a second reflection point), wherein the first reflection point is disposed at a first position inside the hollow coaxial cable-Fabbrero resonator, the second The reflection point is disposed at a second position inside the hollow coaxial cable-Fabrero cavity, and the distance between the two reflection points is generally more than 1 cm.

Here, the hollow coaxial cable-Fabrero resonator is mostly composed of an outer conductor (ie, an outer casing) and an inner conductor (ie, an inner rod). As shown in FIG. 1, the outer casing 1 and the inner rod 2 are continuous conductors. The continuous conductor is a single conductive part or a plurality of conductive parts connected. In an embodiment, there may be only the outer casing 1 without the inner rod 2. In another embodiment, both the outer casing 1 and the inner rod 2 can be provided.

The medium in the cavity between the outer casing 1 and the inner rod 2 is one of: vacuum, gas, liquid, solid; wherein, when the medium is solid, the solid is filled outside the range of movement of the reflection point . The electromagnetic waves traveling in the hollow coaxial cable-Fabbrero resonator are mainly reflected at the first reflection point, and a part of the energy is reflected, and the remaining energy of the remaining portion is transmitted past and reaches the second reflection point. At the second reflection point, again a small portion of the electromagnetic waves are reflected and repeated round trips multiple times (the number of round trips is determined by the reflectivity of the reflection points). The higher the reflectivity of the two reflection points, the more round trips will be, and the higher the quality factor of the reflection amplitude spectrum or the transmission amplitude spectrum of the resonator. In the above solution, the reflection point may be generated by the impedance deviation of the coaxial cable or by a short circuit or an open circuit of the inner and outer conductors. The two reflection points can produce a phase delay δ of the microwave, which is calculated as follows:

Where f is the microwave frequency, ε _r is the dielectric constant of the material inside the coaxial cable (air is 1), d is the frequency of the resonant cavity, and c is the speed of light in the vacuum.

The amplitude spectrum of the reflected electric field and the transmitted electric field of a hollow coaxial cable-Fabbrero resonator is represented by the following formula:

Where r is the reflection amplitude spectrum and t is the transmission amplitude spectrum. R is the reflectance of the reflection point, and equation (2) assumes that the reflectances of the two reflection points are the same and the insertion loss of the Fabry Perot cavity is zero.

3 is a reflection amplitude spectrum and a transmission amplitude spectrum of a hollow coaxial cable-Fabbrero resonator according to an embodiment of the present invention. As shown in Figure 3, multiple resonant frequencies can be observed, including fundamental and harmonics. Many small ripples can be observed in (a) and (b) of Figure 3 due to the incomplete matching of the impedance between the instrument interface and the coaxial cable. The basic idea of making a sensor using a hollow coaxial cable-Fabrero resonator is based on the fact that the distance between the two reflection points can be accurately calculated from the reflection amplitude spectrum or the transmission amplitude spectrum.

The cavity length measuring device of the microwave resonant cavity of the embodiment of the present invention is described in detail below with reference to a specific structure. The cavity length measuring device of the embodiment of the present invention comprises: a microwave resonant cavity and a demodulating device, wherein the microwave resonant cavity refers to FIG. 1 The hollow coaxial cable shown - Fabry Perot cavity. In all embodiments of the invention:

1) The outer casing 1 / inner rod 2 may be a conductor part, or a plurality of conductor parts may be connected together (to ensure electrical conductivity at the joint), it can be seen that the outer casing 1 / inner rod 2 is a continuous conductor. A conductor part in all the drawings does not necessarily represent a simple conductor part, but also a composite conductor part composed of a plurality of conductor parts through different connections.

2) Regarding the movement of the second reflection point:

2.1) When there is both an outer casing and an inner rod, the second reflection point may be separately moved; the second reflection point may be fixed to the outer casing and/or the inner rod, and then the outer casing and/or the inner rod and the second reflection may be moved together Point to achieve the movement of the second reflection point. When the outer casing and/or the inner rod and the second reflecting point are fixed in one piece, moving the second reflecting point causes the partial outer casing and/or the inner rod to move, and the outer casing and/or the inner rod must ensure the electrical conductivity. Therefore, the outer casing and/or the inner rod should be such that a nested structure, a spring structure or a bellows structure can be adapted to a structure that is relatively stretched or compressed and can maintain electrical continuity. Such a structure can be used for a sensor such as a displacement meter mentioned in the embodiment of the invention.

In addition, it is possible to expand and contract when the outer casing and the inner rod are respectively an integral part, that is, without a nested structure. The first reflection point or the second reflection point can move or move separately along with the outer casing and the inner rod; wherein, at the other end of the hollow coaxial cable-Fabrero resonator, a sealing structure or In the case of connecting another RF coaxial cable adapter, the first reflection point or the second reflection point is fixed at one end of a part, and the other end of the part extends beyond the outer casing by pulling the part The movement causes movement of a fixed reflection point thereof, and the part drives the reflection point to have a groove on the area swept to the outer casing during movement so that the part moves along the groove.

2.2) When there is no inner rod in the outer casing, the second reflection point may be separately moved, or the second reflection point may be fixed to the outer casing, and then the outer casing and the second reflection point are moved together to realize the movement of the second reflection point. When the outer casing and the second reflection point are fixed together, moving the second reflection point causes a part of the outer casing to move, and the outer casing must ensure the electrical conductivity. Therefore, the outer casing needs to use a nested structure, a spring structure or a bellows. Structures and the like can accommodate structures that are relatively stretched or compressed and that maintain electrical continuity.

The above is only one of the displacement measurement principles in the embodiment of the present invention. It should be noted that the technical solution of the embodiment of the present invention can implement the following scheme by using any displacement measurement principle: measuring the deflection of the elbow (such as a Bourdon tube) Reflect changes in pressure. Among them, the displacement measurement principle can be realized based on the following equipment: optical distance measuring equipment such as Fabry Perot range finder or optical range finder, displacement sensor such as hollow coaxial cable-Fabrero resonator, EFPI displacement meter, Various principles of displacement gauges such as FBG displacement gauges, vibrating wire displacement gauges or differential resistance displacement gauges.

Embodiment 1: Cavity length measuring device of microwave resonant cavity

The cavity length measuring device comprises: a microwave resonant cavity and a demodulating device; wherein the microwave resonant cavity comprises a hollow coaxial cable-Fabbrero resonator, a first reflection point, and a second reflection point, wherein the first reflection a point disposed at a first position inside the hollow coaxial cable-Fabbrero resonator, the second reflection point being disposed at a second inside the hollow coaxial cable-Fabrero cavity At a position, the first position and/or the second position can be moved; a reflectivity of the first reflection point and the second reflection point is greater than or equal to a preset threshold; the demodulation device and the a microwave cavity connected to analyze the microwave signal in the microwave cavity to obtain a cavity length of the microwave cavity, wherein a cavity length of the microwave cavity is the first reflection point and the The distance between the second reflection points.

The cavity length measuring device in this embodiment is divided into the following three types:

1) Reflective cavity length measuring device, in the reflective cavity length measuring device:

One end of the hollow coaxial cable-Fabbrero resonator is connected to a radio frequency coaxial cable adapter, and the RF coaxial cable adapter is connected to the demodulation device through a coaxial cable, wherein the solution The adjusting device is: a vector network analyzer, or a microwave generating source plus scalar network analyzer, or a microwave time domain reflectometer; the other end of the hollow coaxial cable-Fabbrero resonator is an open structure or a sealing structure Or, connect another RF coaxial cable adapter and the RF coaxial cable adapter is in contact with both the outer casing and the inner rod.

2) The first type of transmissive cavity length measuring device, in the first transmissive cavity length measuring device:

The first end of the hollow coaxial cable-Fabrero resonator is connected to a first RF coaxial cable adapter, and the second end of the hollow coaxial cable-Fabrero resonator is connected to the A radio frequency coaxial cable adapter, wherein the first RF coaxial cable adapter and the second RF coaxial cable adapter are connected to the demodulation device by a coaxial cable.

Here, the cavity length measuring device has at least the following modes: a positive feedback loop mode, a loopless mode; wherein

In the positive feedback loop mode, the demodulation device includes: a directional coupler, a waveform amplifier, a frequency counter/spectrum analyzer, wherein the first RF coaxial cable adapter is connected to the directional coupler, The waveform amplifier and the second RF coaxial cable adapter are sequentially connected, and the frequency/spectrum analyzer is connected to the directional coupler;

In the loop-free mode, the demodulation device is a vector network analyzer, or a scalar microwave analyzer.

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

In the microwave positive feedback loop, comprising: a coaxial cable loop, a microwave directional coupler, a microwave amplifier or a microwave power splitter, wherein each device in the demodulation device is connected by a coaxial cable loop;

In the positive feedback loop based on the photoelectric oscillator, including: high-speed photodiode, laser or LED source, fiber loop, fiber coupler, microwave amplifier or optical amplifier, microwave directional coupler or microwave power separation And a frequency meter/spectrum analyzer, each of the devices in the demodulation device being connected by a fiber loop.

3) A second transmissive cavity length measuring device, in the second transmissive cavity length measuring device:

The first end of the hollow coaxial cable-Fabrero resonator is connected to a first RF coaxial cable adapter, and the outer wall of the hollow coaxial cable-Fabrero resonator is connected to the second The RF coaxial cable adapter, the first RF coaxial cable adapter and the second RF coaxial cable adapter are connected to the demodulation device by a coaxial cable.

In the positive feedback loop mode, the demodulation device includes: a directional coupler, a waveform amplifier, a frequency counter/spectrum analyzer, wherein the first RF coaxial cable adapter is connected to the directional coupler, The waveform amplifier and the second RF coaxial cable adapter are sequentially connected, Connecting the frequency meter/spectrum meter to the directional coupler;

In the microwave positive feedback loop, including: a coaxial cable loop, a microwave directional coupler, a microwave amplifier or a microwave power splitter, a frequency counter/spectrum analyzer, each device in the demodulation device passes through a coaxial Cable loop connection;

In this embodiment, the labels of the respective core devices are as follows: the outer casing 1, the inner rod 2, the first reflection point 3, the second reflection point 4, the resonant cavity 5, the RF coaxial cable adapter 6, the vector network analyzer or the scalar microwave. Analyzer 9, directional coupler 10, waveform amplifier 11, frequency counter 12, RF coaxial cable adapter 13, wherein:

The outer casing 1 refers to a continuous conductor connected to the outer ring of the RF coaxial cable adapter, the conductor may be a tube, may be a semi-circular tube, may be a spring, may be a rod, or may be a plurality of conductors through the conductive connection Connected composite conductors. For example: two or more nested conductor tubes, two or more conductor tubes that are connected by metal connectors, and the like. Figure 4 shows a cross-sectional view of the housing. Figure 7 illustrates the common connections between different sections of the housing when multiple parts form the housing.

The inner rod 2 is also a continuous conductor. Like the outer casing 1, the inner rod 2 can also have different geometric shapes, and the cross-sectional shape can be circular, rectangular or semi-circular, etc., and can be a straight rod, which can be a curved rod such as a spring. It may be a connector in which a plurality of conductors are connected together. Cavity length measurement under special circumstances The device can be used to demodulate the signal through the demodulation device without the inner rod, and the required parameters can still be measured. Figure 5 shows a cross-sectional view commonly used for the inner rod. Figure 7 shows the common connection between the rods in different sections when multiple parts form the inner rod.

The first reflection point 3 and the second reflection point 4 refer to some objects within the envelope of the outer casing and the inner rod, which may be various shapes, may be different sizes, different materials, or may be multiple parts. combination. As long as it can play a role in reflection. If the reflection point is a conductor that connects the outer casing to the inner rod, then the reflectivity at this point will be high, and if it is not the outer casing and the inner rod conductor, the reflectivity will be lower. Figure 6 shows a cross-sectional view of a common reflection point, in which the shaded portion is a reflection point.

The resonant cavity 5 refers to a resonant cavity between the first reflective point and the second reflective point, and between the outer casing and the inner rod. Generally, the medium in the resonant cavity is vacuum, gas, liquid or solid, and if it is solid, then Solids cannot be filled into the range of movement of the reflection point so that the movement of the reflection point is not affected.

The RF coaxial cable adapter 6 generally adopts an SMA connector or other connectors. The outer ring of the RF coaxial cable adapter 6 is connected to the outer casing 1. The center signal pin 7 of the RF coaxial cable adapter is connected to the inner rod 2. In addition, the RF coaxial cable adapter 13 is generally a male or female male connector. The interface between the demodulation device and the microwave cavity is not limited to the commonly used SMA connector or the male or female male connector, and may be other forms of RF coaxial cable adapter.

The vector network analyzer or scalar microwave analyzer 9 is a device for measuring the reflection amplitude spectrum or transmission amplitude spectrum of a hollow coaxial cable-Fabbrero resonator.

The directional coupler 10 is a key component for forming a positive feedback circuit.

The waveform amplifier 11 is a device for increasing the suppression ratio of the positive feedback circuit.

The frequency counter 12 is for measuring the reflected or transmitted resonant frequency of a hollow coaxial cable-Fabbrero resonator.

The directional coupler 10, the waveform amplifier 11 and the frequency counter 12 together form a positive feedback demodulation system of a hollow coaxial cable-Fabrero resonator, and a vector network analyzer or a scalar microwave analyzer 9 For the same reason, they are called demodulation devices.

1 is a core element of a hollow coaxial cable-Fabbrero resonator, including a housing 1, an inner rod 2, a first reflection point 3, a second reflection point 4, and a resonant cavity 5.

(a) and (b) in Fig. 2 respectively show two cases in which the hollow coaxial cable-Fabbrero resonator does not include the inner rod and the inner rod, wherein the outer casing and the inner rod may have various shapes. It may be a connection structure of a plurality of conductors, and the two reflection points may be within the envelope of the outer casing 1 and the inner rod 2.

Figure 4 shows a cross-sectional view of a conventional housing 1 which may be a ring, a box or a variety of irregular shapes, and the housing may even be a spring or a round rod. It is also possible to divide the combination of a plurality of conductors together as long as the continuous conductor is satisfied.

Figure 5 shows a cross-sectional view of a conventional inner rod 2, which may be hollow or solid, and may have a variety of cross-sections. Common cross-sections are circular, rectangular and regular polygons. The inner rod 2 may be a spatially curved structure such as a spring. The inner rod 2 can also be divided into a combination of a plurality of conductors connected as long as the continuous conductor is satisfied.

Figure 6 is a cross-sectional view of a

conventional reflection point

3 or 4, which may be of various shapes. The reflection point may be a conductor or an insulator as long as there is a portion within the envelope of the outer casing 1 and the inner rod 2; the reflection point may or may not be in contact with the outer casing and/or the inner rod. For example, in the case where the outer casing 1 is a cylinder and the inner rod is a round rod, the reflection point may be a cylinder or a torus filled between the outer casing 1 and the inner rod 2, or may be a cover portion outer casing 1 An object that is in a cavity with the inner rod 2, such as a small round rod or a porous disc as shown in the third, fourth and fifth figures in Fig. 6.

Fig. 7 is a schematic view showing the connection of the outer casing to the outer casing or the inner rod and the inner rod after the outer casing 1 or the inner rod 2 is connected in sections. Figure 7 shows the usual connection methods, including lap joints, misalignment, nesting, or connection with a rotating shaft, and connection with a conductor bellows, in which case occurs between different sections of the segmented outer casing 1 or inner rod 2. When the relative movement or rotation is performed, the conductive continuity of the outer casing 1 or the inner rod 2 may be satisfied.

Implementation 2: Displacement sensor

The displacement sensor includes the cavity length measuring device of the first embodiment, wherein a cavity length variation of the microwave cavity characterizes a displacement of the second reflection point relative to the first reflection point. Here, a displacement sensor based on a hollow coaxial cable-Fabrero resonator is cited. The four configurations of the displacement sensor are as shown in (a), (b), (c), and (d) of FIG.

Fig. 8(a) is a schematic structural view of a displacement sensor based on a reflective hollow coaxial cable-Fabrero resonator. When there is no inner rod 2, the outer casing 1 is connected to the radio frequency coaxial cable adapter 6. When there is an inner rod 2, both the outer casing 1 and the inner rod 2 are connected to the radio frequency coaxial cable adapter 6. 3 and 4 are the first reflection point and the second reflection point respectively. If the outer casing 1 and the inner rod 2 are connected to the radio frequency coaxial cable adapter 6, the connection portion has a certain reflectivity, and the connection can be used as the first A reflection point. A vector network analyzer or scalar microwave analyzer 9 is used to transmit and receive microwave signals to determine the length of the resonant cavity 5, that is, the effective distance between the first reflective point 3 and the second reflected point 4. The probe 22, the sleeve 21 of the inner rod and the second reflection point 4 have an integral structure. When displacement occurs, the displacement moves by the moving probe 22 to move the second reflection point 4, and the movement amount of the second reflection point 4 is displacement. the amount.

The transmission structure used in the displacement sensor means that the RF coaxial cable adapter 6 is connected to the outer casing 1 and the inner rod 2 at the left end of the outer casing 1 and the inner rod 2. When there is no inner rod 2, it is meant that the RF coaxial cable adapter 6 is connected to the outer casing 1 at the left end of the outer casing 1 and the inner rod 2. Another RF coaxial cable adapter 13 is attached to the wall of the housing rather than at the right end.

Fig. 8(b) is a schematic view showing the structure of a displacement sensor based on a transmission structure of a hollow coaxial cable-Fabrero resonator and having a positive feedback loop. An RF coaxial cable adapter 6 is attached to the left end of the outer casing 1 with or without the inner inner rod 2. Taking the case of the inner rod 2 as an example, the left end of the inner rod 2 is connected to the center signal pin 7 of the radio frequency coaxial cable adapter 6. The two

reflection points

3 and 4 are between the outer casing 1 and the inner rod 2, and in particular, the connection of the outer casing 1, the inner rod 2 and the radio frequency coaxial cable adapter 6 can serve as a reflection point. Secure an RF coaxial cable adapter at a point on the enclosure And the RF coaxial cable adapter is connected to the waveform amplifier 11 via a coaxial cable, the RF coaxial cable adapter 6 is connected to the directional coupler 10 by a coaxial cable, and 10 and 11 are connected, and finally oriented The coupler 10 is connected to the frequency counter 12. The probe 22, the sleeve 21 of the inner rod and the second reflection point 4 have an integral structure. When displacement occurs, the displacement moves by the moving probe 22 to move the second reflection point 4, and the movement amount of the second reflection point 4 is displacement. the amount.

Fig. 8(c) is a schematic structural view of a displacement sensor based on a transmission structure of a hollow coaxial cable-Fabrero resonator and without a loop. An RF coaxial cable adapter 6 is attached to the left end of the outer casing 1 with or without the inner inner rod 2. Taking the case of the inner rod 2 as an example, the left end of the inner rod 2 is connected to the center signal pin 7 of the radio frequency coaxial cable adapter 6. The two

reflection points

3 and 4 are between the outer casing 1 and the inner rod 2, and in particular, the connection of the outer casing 1, the inner rod 2 and the radio frequency coaxial cable adapter 6 can serve as a reflection point. The two RF

coaxial cable adapters

6 and 13 are respectively connected to a vector network analyzer or a scalar microwave analyzer 9 via a coaxial cable to form a transmissive loop. The probe 22, the sleeve 21 of the inner rod and the second reflection point 4 have an integral structure. When displacement occurs, the displacement moves by the moving probe 22 to move the second reflection point 4, and the movement amount of the second reflection point 4 is displacement. the amount.

It should be noted that, in the embodiment of the present invention, the outer casing 1 and the inner rod 2 in FIGS. 8(a), (b) and (c) are not necessarily one conductor part, but a plurality of conductor parts may be connected together, but Make sure the conductivity at the connection. Regarding the movement of the second reflection point, when there is both the outer casing and the inner rod, the second reflection point may be separately moved, or the second reflection point may be fixed to the outer casing or the inner rod or both, and then the outer casing may be moved together. The inner rod and the second reflection point are used to achieve the movement of the second reflection point. When the outer casing, the inner rod and the second reflection point are fixed in one piece, moving the second reflection point causes the partial outer casing and the inner rod to move, and the outer casing and the inner rod must ensure conductive connection. Therefore, the outer casing and the inner rod should use a nested structure, a spring structure or a bellows structure to accommodate a structure that is relatively stretched or compressed and can maintain electrical continuity, as shown in FIG. When there is no inner rod, the conductive continuity of the outer casing can be ensured.

In addition, a displacement sensor based on a hollow coaxial cable-Fabrero resonator has a special case, as shown in Fig. 8(d), considering the left end of the cavity connected to the RF coaxial cable adapter. At this time, the right end of the resonant cavity may be open, may be sealed, or may be connected to a coaxial cable adapter and the coaxial cable adapter is in contact with the outer casing and the inner rod. Figure 8(d) shows the operating condition of the coaxial cable adapter at the right end. Taking the movement of the second reflection point 4 as an example, the reflection point is moved by one end of one part 20 to the second reflection point 4, and the other end extends beyond the outer casing, and the reflection point is driven by pulling the movement of the part 20. The movement. Since the part 20 and the second reflection point 4 are integrally connected, the part 20 and the second reflection point 4 are connected to a part of the outer casing during the movement, and need to be grooved on the outer surface of the outer casing to facilitate the part. The movement of the 20 and the reflection point does not affect the electrical continuity of the outer casing.

In the embodiment of the present invention, the type of the displacement sensor represented by 40 may also be a displacement sensor based on a hollow coaxial cable-Fabrero cavity, an EFPI displacement sensor, an FBG displacement sensor, a vibrating wire displacement sensor or a differential displacement displacement. Displacement sensors of various principles such as sensors.

Embodiment 3: Mode of the elbow and fixing method of the displacement sensor

There are many types of elbows. As long as they are not straight tubes, they can be defined as elbows. The axis of the elbow can be a curve or a fold line in the plane, or a space curve such as a space spiral; the cross section of the tube can be a circle The ring, the elliptical ring shape, or the square tubular shape and the like may have various closed shapes; each of the sections of the tube may be of the same shape and size, or may be of different shapes and sizes, such as a variable diameter structure or the like. The common shapes of some elbows are listed in Figure 9. The basic feature of the elbow is that one end is closed, the other end can be closed, or the other end can be sealed with a diaphragm that can be deformed by pressure. The most common bend is the Bourdon tube. The embodiment of the invention exemplifies the working principle and performance of the displacement sensor by using a C-type Bourdon tube.

The fixing method of the displacement sensor has certain requirements. The most important core criterion is that the distance between the fixed point of the displacement sensor body such as electric or optical and the fixed point of the baffle or the reflector is determined after the deformation of the bend occurs. Have a relative displacement. Corresponding by different pressures The magnitude of the displacement is used to calibrate the pressure. Taking the principle of a displacement sensor based on a hollow coaxial cable-Fabrero cavity as an example, since the rotation between the two fixed points is not excluded, generally the tip 34 of the probe is fixed on the clamp 35. Either the end 34 of the probe and the clamp 35 are connected by one or more hinged parts so that they can accommodate the relative rotatory between the two fixed points. Figure 10 shows the connection between the ends 34 of the five probes and the clamp 35. Of course, other connection methods such as ball joints can also be used.

It is worth noting that when measuring using the optical ranging method, it is only necessary to ensure that the optical axis 64 is substantially perpendicular to the baffle.

The pressure sensor in the embodiment of the present invention includes: a displacement sensor, an elbow, and a base; the first end of the elbow is fixed on the base, wherein the displacement sensor comprises a first reflective component and a second reflective component. The first reflecting member is fixed in a body of the displacement sensor, the second reflecting member is movable relative to a body of the displacement sensor; a body of the displacement sensor is fixed on the base, the second reflection a member is coupled to the elbow at a first position of the elbow; or the second reflective member is fixed to the base, the body of the displacement sensor being at a first position of the elbow The elbow is connected; when the pressure in the elbow changes, the elbow deforms and drives a reflective member to move, causing a change in the distance between the first reflective member and the second reflective member. The magnitude of the pressure change is obtained by the magnitude of the displacement measured by the displacement sensor.

The pressure sensor of the embodiment of the present invention will be specifically explained below based on various types of displacement sensors.

Embodiment 4: Pressure sensor for measuring deflection of an elbow based on a displacement sensor of a cavity length measuring device of a microwave cavity

The displacement sensor of the cavity length measuring device based on the microwave cavity shown in FIGS. 8(a), (b), and (c) is fixed to the base 32 of the elbow by the component 33 of the fixed sensor protruding from the base; the jig 35 A point to be fixed on the elbow is mostly fixed at the vertex or end point, as shown in Figure 13; At the same time, the probe end 34 of the displacement sensor and the clamp 35 can be fixedly integrated, and the displacement sensor probe end 34 can also be directly mounted on the clamp 35, or can be fastened or hingedly fixed to the clamp 35 by the connecting component. After the internal deformation of the elbow is deformed, the point of the fixing jig 35 on the elbow moves relative to the base 32, thereby causing the displacement sensor probe end portion 34 to move, and the displacement sensor 40 end portion 34 is measured by the displacement sensor 40. The amount reflects the magnitude of the pressure. The data can be derived via the coaxial cable transmission line 8 and the measured displacement is obtained by the demodulation system 41. If it is the displacement sensor shown in Fig. 8(d), the displacement gauge main body is fixed to the base 32, and the second reflection point 4 is moved by one end of one part 20 to the second reflection point 4, and the other end is extended. Outside the outer casing, the part 20 is fixed at a point on the elbow, and the movement of the part 20 is driven by the deformation of the elbow to drive the movement of the reflection point.

Figure 10 shows several methods of connecting the displacement sensor tip to the elbow, 34 indicates the end of the displacement sensor, and 35 indicates the clamp. The two can be hinged or contacted but not fixed. They can also be fixedly connected or used. Multiple hinges are connected. In short, it can be ensured that when the point on the elbow moves, the end of the displacement sensor can be moved.

Figure 11 (a), (b), (c) and (d) list several methods of fixing the displacement sensor and the baffle. The common method is to fix the displacement sensor on the base and the probe is fixed on the elbow; Or the probe is fixed on the base and the displacement sensor is fixed on the elbow. The displacement sensor is perpendicular to the axis of the baffle, and the axis of the displacement sensor and the direction of the baffle can be directed in any direction. As long as the bending tube is deformed under pressure, the fixing method of the displacement amount of the displacement meter can be changed.

Figure 12 is a special shape displacement sensor based pressure sensor. The displacement sensor 40 is fixed to the base 32 of the elbow by means of a fixed sensor part 33 projecting from the base. The elbow 30 is a spiral tube and the displacement gauge is probed. The rod end fixed clamp 35 is fixed to the top of the spiral tube, and the axis of the displacement sensor coincides with the axis of the spiral tube, so that when the pressure changes, the movement direction of the displacement sensor probe is the axial direction of the displacement sensor, and the displacement can be made. The amount of movement of the sensor probe end portion 34 exceeds that of a general C-type Bourdon tube to improve measurement accuracy.

Embodiment 5: In the displacement sensor of the cavity length measuring device based on the microwave cavity, the bending pipe is used as the pressure sensor of the second reflection point

Figure 13 is another special pressure sensor based on a curved tube as a second reflection point. This sensor is a sensor that measures the cavity length based on a reflective or transmissive microwave cavity. The figure shows the reflective cavity length measuring device, as shown in Figure (a); the first transmissive cavity length measuring device with positive feedback loop, as shown in Figure (b); the first transmissive and acyclic The cavity length measuring device of the road is shown in Figure (c); the second transmissive cavity length measuring device with positive feedback loop is shown in Figure (d); the second transmissive and loop-free cavity length measurement The device is shown in Figure (e). On this basis, the structural characteristics of the pressure sensor are explained below.

Assume that the first reflection point is a fixed point, and one elbow is used as the second reflection point. The elbow is closed at one end of the tube, and the other end of the tube can directly lead to a gas or liquid with pressure outside the tube. It is also possible to connect to the end of the tube with a deformable diaphragm, which is water pressure or air pressure, similar to a common Bourdon tube. In this way, the water pressure or the air pressure squeezes the deformation of the diaphragm, and the deformation of the elbow can be caused by the pressure of the liquid in the elbow of the diaphragm extrusion, so that the deflection of each point of the elbow changes. According to the schematic diagram in Fig. 13, when the pressure is changed, the end of the elbow moves left and right, thereby changing the position of the second reflection point, and the magnitude of the pressure can be determined by the amount of change in the position of the second reflection point.

Similarly, the second reflection point can be fixed, and the elbow is used as the first reflection point. It can also be installed in reverse with two elbows as two reflection points. When the pressure changes, the two elbows move in opposite directions, which improves the sensitivity of the pressure sensor.

Embodiment 6: Pressure sensor for measuring deflection of a bend based on an extrinsic Fabry Perot interference (EFPI) instrument

Based on the EFPI principle pressure sensor, the fiber end face is fixed as a first reflecting surface 50 to the base 32 of the elbow by a fixed sensor component 33 projecting from the base; the second reflecting surface 51 is fixed to the elbow by means of

parts

34 and 35. a point on the upper and through the hinge between

parts

34 and 35 The angle is adjusted such that the axis of the fiber can be exactly perpendicular to the second reflecting surface 51, ie the first reflecting surface 50 is parallel to the second reflecting surface 51. In most cases, the part 35 is fixed at the vertex or end point as shown in FIG. In short, after the internal deformation of the elbow is deformed, the

upper parts

34 and 35 of the elbow will move the second reflecting surface 51 relative to the base 32, that is, move relative to the first reflecting surface 50, and measure the first reflecting surface to the second. The change in distance between the reflecting surfaces reflects the magnitude of the pressure. At the time of measurement, the signal can be transmitted to the spectral demodulation system through the transmission fiber 52, thereby obtaining the cavity length of the EFPI by demodulation. The entire sensor is protected by a housing 55 that is protected by a fiber optic cover 52 and sealed with a sealing plug 54 where the fiber extends out of the housing.

In this embodiment, when the first reflecting surface and the second reflecting surface are mounted, it is only necessary to ensure that the two reflecting surfaces are parallel, that is, as long as the fiber axis is perpendicular to the second reflecting surface. There is no specific requirement for the normal direction of the first reflecting surface and the second reflecting surface. For example, the second reflecting surface 51 is not necessarily parallel to the tangent of the elbow at the fixed second reflecting surface, as shown in FIG. 14(d). Of course, the optical fiber can also be fixed on the elbow, and the second reflective surface is fixed on the base as shown in Fig. 14(c). It is also possible to fix both the optical fiber and the second reflecting surface to the elbow, and any structure in which the cavity length of the EFPI changes can be used as long as the pressure is changed.

Embodiment 7: Pressure sensor based on optical range finder

The solution of the embodiment of the present invention is similar to the sensor of Embodiment 6, except that the EFPI in Embodiment 6 can measure the small cavity length variation with high precision, that is, the distance between the first reflective surface and the second reflective surface generally does not exceed 1mm. Optical rangefinders can measure large changes in cavity length, ranging from micrometers to meters. Optical range finder can use different ranging principles, such as infrared range finder or laser range finder and other optical range finder. The structure of the pressure sensor is shown in Figure 15.

The optical range finder 60 is secured to the base 32 of the elbow by means of a fixed sensor component 33 projecting from the base; the reflector 61 is secured to a point on the elbow by means of

parts

34 and 35 and passes through the

parts

34 and 35. The hinges are adjusted to adjust the angle so that the optical axis 64 of the optical rangefinder can be vertical On the reflector 61. In most cases, the part 35 is fixed at the vertex or end point as shown in FIG. In short, after the internal deformation of the elbow is deformed, the

parts

34 and 35 on the elbow will move the reflector 61 relative to the base 32, that is, move relative to the optical range finder 60, and measure the optical range finder 60 and the reflector 61. The change in distance between the two can reflect the magnitude of the pressure. The entire sensor is protected by a housing 55 which is protected by a cable gland 63 and which is sealed with a sealing plug 54 where the transmission cable 62 extends out of the housing.

In the present embodiment, when the optical range finder 60 and the reflector 61 are mounted, as long as the optical axis 64 is substantially perpendicular to the reflector, the verticality is not as high as that required by the EFPI sensor of the fifth embodiment. There is no particular requirement for the direction of the optical axis 64 and the normal to the reflector, i.e., as long as the optical axis 64 is substantially perpendicular to the reflector. For example, the normal line of the reflector 51 is not necessarily perpendicular to the tangent of the elbow at the fixed reflector, as shown in Fig. 15(d). Of course, the optical range finder 60 can also be fixed on the elbow, and the reflector 61 is fixed on the base as shown in FIG. 15(c).

Figure 16 is a special shape of an optical distance meter based pressure sensor. The optical range finder 60 is fixed to the base 32 of the elbow by means of a fixed sensor component 33 extending from the base. The elbow 30 is a spiral tube. The optical axis 64 of the optical range finder overlaps with the axis of the spiral tube, so that when the pressure changes, the moving direction of the reflecting plate 61 is the direction of the spiral axis, that is, the direction of the optical axis 64, and the amount of movement of the reflecting plate 61 can be exceeded. The general C-type Bourdon tube improves measurement accuracy.

The technical solutions described in the embodiments of the present invention can be arbitrarily combined without conflict.

The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention.

Industrial applicability

According to the technical solution of the embodiment of the present invention, the pressure sensor includes: a displacement sensor, an elbow, and a base; the first end of the elbow is fixed on the base, wherein the displacement sensor includes a reflective member, the second reflective member, the first reflective member being fixed in a body of the displacement sensor, the second reflective member being movable relative to a body of the displacement sensor; the body of the displacement sensor being fixed at the On the base, the second reflective member is coupled to the elbow at a first position of the elbow; or the second reflective member is fixed to the base, the main body of the displacement sensor is a first position of the elbow is connected to the elbow; when the pressure changes, the elbow deforms and drives a reflective member to move, resulting in the first reflective member and the second reflective member The distance between the two changes, and the magnitude of the displacement is obtained by the magnitude of the displacement measured by the displacement sensor. The technical solution of the embodiment of the invention has at least the following advantages: high measurement accuracy, high signal to noise ratio, and high cost performance of the device.

Claims

A pressure sensor includes: a displacement sensor, an elbow, and a base; the first end of the elbow is fixed on the base, wherein

The displacement sensor includes a first reflective member, a second reflective member fixed in a body of the displacement sensor, the second reflective member being movable relative to a body of the displacement sensor;

a body of the displacement sensor is fixed on the base, the second reflection member is connected to the elbow at a first position of the elbow; or the second reflection member is fixed on the base The body of the displacement sensor is coupled to the elbow at a first position of the elbow;

When the pressure in the elbow changes, the elbow deforms and drives a reflective member to move, causing a change in the distance between the first reflective member and the second reflective member, through the displacement sensor The magnitude of the measured displacement gives the magnitude of the pressure change.
The pressure sensor according to claim 1, wherein the displacement sensor is a displacement sensor of a cavity length measuring device based on a microwave cavity, the cavity length measuring device is a reflective cavity length measuring device, or a second transmissive type The cavity length measuring device, wherein the two reflecting members of the displacement sensor refer to two reflecting points whose reflectance is greater than or equal to a threshold.
The pressure sensor of claim 2 wherein the second reflection point of the displacement sensor is coupled to the probe:

The displacement sensor is fixed on the base by a part of the base for fixing the displacement sensor;

The probe end of the displacement sensor is fixedly integrated with the baffle, and the baffle is fixed at the first position of the elbow, wherein the first position is an apex or an end point of the elbow; After the bent pipe is deformed by the pressure, the fixed point on the curved pipe for fixing the baffle moves relative to the base, thereby driving the end of the probe of the displacement sensor to move through the displacement sensor Measuring the magnitude of the movement of the end of the probe to obtain a pressure; or

The probe end of the displacement sensor is fixed at a first position of the elbow by a linkage member, wherein the first position is a point on the elbow, and a point on the elbow includes at least a vertice or an end point; after the elbow is deformed by the pressure, the linking member on the elbow drives the end of the probe to move, thereby causing the second reflection point to move, through the displacement The amount of movement of the second reflection point measured by the sensor is obtained by the magnitude of the pressure.
The pressure sensor according to claim 3, wherein the probe end of the displacement sensor is integrally fixed to the baffle means:

The probe end of the displacement sensor is directly mounted on the baffle; or

The probe end of the displacement sensor is connected to the baffle by a connecting part, wherein the connecting part is a just-connected part or a hinged part.
The pressure sensor of claim 2 wherein the second reflection point of the displacement sensor is coupled to the probe:

The probe of the displacement sensor is fixed on the base by a part protruding from the base for fixing the probe;

The end of the displacement sensor is fixedly integrated with the baffle, and the baffle is fixed at the first position of the elbow, wherein the first position is an apex or an end point of the elbow;

After the bending tube is deformed by the pressure, the fixing point of the bending tube for fixing the baffle moves relative to the base, thereby driving the end of the displacement sensor to move, and measuring by the displacement sensor The resulting movement of the probe is given a magnitude of pressure.
The pressure sensor according to claim 2, wherein the first reflection point of the displacement sensor is fixed to the first section of the outer casing and the inner rod, the second reflection point of the displacement sensor and the second section of the outer casing and the inner rod Fixed, the outer casing and the inner rod adopt a structure capable of stretching or compressing and maintaining electrical continuity, and the structure capable of stretching or compressing and maintaining electrical continuity is: the first section of the outer casing and the inner rod And the second section is connected by at least the following structure: a nested structure, or a spring structure, or a bellows structure; the second section of the displacement sensor is integrally used as a probe, wherein The structure of the outer fixing protrusion of the outer casing at the first reflection point serves as a first fixing point, and the structure of the outer fixing protrusion of the outer casing at the second reflection point serves as a second fixing point;

The first fixing point is fixed on the base;

The second fixing point is directly fixed at the first position of the elbow; or the second fixing point is fixed to the baffle by a hinge part, the baffle being fixed at the first position of the elbow Where the first position is a vertex or an end point of the elbow.
The pressure sensor according to any one of claims 2 to 6, wherein the elbow is a spiral tube, an axis of the displacement sensor coincides with an axis of the spiral tube, wherein the elbow is deformed by pressure Thereafter, the moving direction of the probe of the displacement sensor coincides with the axial direction of the displacement sensor.
The pressure sensor according to any one of claims 2 to 6, wherein the first end of the elbow is a closed structure, and the second end is a non-closed structure; or the first end of the elbow is a closed structure After the liquid is filled in the elbow, the second end of the elbow is sealed by a membrane, and the diaphragm can be deformed when pressed to squeeze the liquid in the elbow.
The pressure sensor according to claim 1, wherein the displacement sensor is a displacement sensor based on a cavity length measuring device of the microwave cavity, and at least one of the reflection points uses a bent pipe inside the casing, and the cavity length measuring device A reflective cavity length measuring device, or a first transmissive cavity length measuring device, or a second transmissive cavity length measuring device, wherein:

The first reflecting member of the displacement sensor is a first reflecting point fixed in a range of an outer casing and an inner rod envelope, and the second reflecting member of the displacement sensor is fixed to the outer casing and at least a part is in the outer casing and a bent pipe within the inner rod envelope; or,

The first reflecting member of the displacement sensor is the elbow fixed to the outer casing and at least a part of which is within the outer casing and the inner rod envelope, and the second reflecting member of the displacement sensor is a fixed outer casing and an inner rod package The first reflection point within the range; or,

The first reflecting member of the displacement sensor is fixed on the outer casing and at least a part is a first elbow in the outer casing and the inner rod envelope, the second reflective member of the displacement sensor being fixed to the outer casing and at least a portion of which is a second elbow within the outer casing and the inner rod envelope, The first elbow and the second elbow are installed in opposite directions, and the two elbows as reflection points are movable in opposite directions when the pressure is changed.
The pressure sensor according to claim 9, wherein the first end of the elbow is a closed structure, and the second end of the elbow is connected to a pressure-bearing gas or liquid outside the tube; or the bend The first end of the tube is a closed structure, and the second end of the elbow is provided with a membrane through which the membrane is in contact with a gas or liquid with pressure, wherein the elbow is a liquid or a gas;

After the elbow is deformed by water pressure or air pressure, each point of the elbow can be moved, and the magnitude of the movement of the measuring point on the elbow is measured by the displacement sensor to obtain a pressure.
The pressure sensor according to claim 1, wherein the displacement sensor is a displacement sensor based on an extrinsic Fabry-Perot interferometer EFPI, in the extrinsic Fabry Perot interferometer, first The reflective surface refers to the end face of the fiber, and the second reflective surface refers to the mirror.
The pressure sensor according to claim 11, wherein

The optical fiber including the first reflecting surface is fixed on the base by a component for fixing the optical fiber protruding from the base;

The mirror including the second reflecting surface is fixed at a first position of the elbow by a connecting part, wherein the first position is an apex or an end point of the elbow or other opposite base on the elbow can occur Moving point

The connecting part includes a fixture fixed to the elbow and a part fixing the mirror, wherein the fixture fixed to the elbow is fixed to the elbow, and the part of the fixed mirror is fixed to the elbow On the upper clamp, the part of the fixed mirror and the fixture fixed to the elbow may be connected to the rigid joint or the hinged part; wherein the axis of the end of the optical fiber is perpendicular to the second reflective surface ;

After the bending tube is deformed by the pressure, the connecting part drives the second reflecting surface to be opposite The first reflecting surface moves, and the amount of change in the cavity length between the first reflecting surface and the second reflecting surface measured by the extrinsic Fabry Perot interferometer displacement sensor is pressurized. size.
The pressure sensor according to claim 1, wherein the displacement sensor is an optical range finder-based displacement sensor in which a fixed point for fixing an optical range finder and a fixed reflection are used The fixed point of the plate can move relative to each other after the bent pipe is deformed.
The pressure sensor according to claim 13, wherein

The optical range finder is fixed on the base by a part extending on the base for fixing the optical range finder;

The reflector is fixed at a first position of the elbow by a connecting part, wherein the first position is a point at which an apex or an end point of the elbow or other opposite base on the elbow can move;

The connecting part includes a fixing member and a reflector, wherein the fixing member is fixed to the reflector, the fixing member is fixed at a first position of the elbow, and the fixing member passes through the reflector Hinged parts connection;

After the bending tube is deformed by the pressure, the connecting component drives the reflector to move relative to the optical range finder, and the reflector is measured by the displacement sensor based on the optical range finder to the The change in the distance between the optical rangefinders gives the magnitude of the pressure.
The pressure sensor according to claim 13 or 14, wherein the elbow is a spiral tube, and an optical axis of the optical range finder coincides with an axis of the spiral tube, wherein the bent tube is deformed by pressure Thereafter, the moving direction of the reflecting plate coincides with the axial direction of the spiral tube.
The pressure sensor according to claim 1, wherein

The shape of the elbow is non-linear, wherein the axis of the elbow is a curve or a broken line in a plane, or a curve in a space, and the curve in the space includes at least a spiral;

The curved pipe has a closed shape, and the closed shape includes at least a circular ring, an elliptical ring, and a square hole shape, wherein each of the curved pipes has the same shape and/or size, or has a different shape. And / or size.
The pressure sensor according to claim 1, wherein the displacement sensor further comprises at least: an FBG displacement meter, or a vibrating wire type displacement meter, or a differential resistance type displacement meter, wherein the displacement sensor measures the elbow by measuring The deflection is used to calculate the pressure.