CN112129401A

CN112129401A - Magnetic fluid dynamic line vibration sensor with runway-type structure

Info

Publication number: CN112129401A
Application number: CN202011108936.8A
Authority: CN
Inventors: 徐梦洁; 李醒飞; 周子晨
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2020-10-16
Filing date: 2020-10-16
Publication date: 2020-12-25

Abstract

The invention discloses a magnetic fluid dynamic line vibration sensor with a runway-type structure.A metal shell of the sensor consists of a base and an end cover, wherein a groove is formed in the base; the inside of shell is provided with: a C-shaped magnetic circuit surrounding the permanent magnet and the fluid passage; permanent magnets which are arranged on two sides of the outer plane of the fluid channel and are positioned at two ends of the opening of the C-shaped magnetic circuit; the fluid channel is internally provided with a fluid cavity, and a conductive fluid is filled in the fluid cavity; the upper wall and the lower wall of the bottom straight channel section of the fluid channel contacted with the permanent magnet are respectively provided with a first electrode and a second electrode. The invention has the characteristics of wide frequency band, low noise, low power consumption, high reliability, small volume, light weight and long service life, and can stably work in severe environments such as strong impact and the like.

Description

Magnetic fluid dynamic line vibration sensor with runway-type structure

Technical Field

The invention relates to the field of magnetohydrodynamics, in particular to a magnetohydrodynamics line vibration sensor based on a runway-type structure.

Background

At present, the aerospace technology is an important standard for measuring the national development level, and the analysis and design of the mechanical environmental conditions of the spacecraft are bottleneck technologies for restricting the improvement of the overall design level of the spacecraft in China. The mechanical environment of the spacecraft refers to the environments of vibration, acceleration, noise, microgravity and the like suffered by the spacecraft in the operation process. Therefore, the broadband and low-noise linear vibration sensor can be used for meeting the requirement of the broadband high-precision mechanical environment test of the spacecraft.

The existing commonly used spacecraft vibration measuring sensor has a pressure resistance type linear vibration sensor and a piezoelectric type linear vibration sensor. The piezoresistive vibration measuring sensor is used for low-frequency vibration measurement, and has the problems of high noise and high influence of temperature; the piezoelectric type linear vibration sensor is used for high-frequency vibration measurement and has the problems of low measurement precision and incapability of measuring static signals. Other vibration measuring sensors, such as: the quartz flexible vibration sensor is easily influenced by environmental factors such as time, temperature and the like to cause unstable measurement; the electrostatic vibration sensor based on the electrostatic suspension principle has the advantages of narrow bandwidth and long production period; the vibrating beam vibration sensor based on the mechanical resonance principle has the problem of frequency locking caused by the mechanical coupling effect.

Disclosure of Invention

The invention aims to provide a magnetohydrodynamic linear vibration sensor sensitive to linear vibration aiming at the defects in the prior art, so that a vibration signal in a wider frequency range can be measured with higher efficiency, and the sensor can stably work in severe environments such as strong impact.

The technical scheme adopted by the invention is as follows:

the invention relates to a magnetic fluid dynamic line vibration sensor with a runway-type structure, which comprises a metal shell and is characterized in that the metal shell is composed of a base and an end cover, and a groove is arranged in the base; the recess forms a cavity with the end cover is inside jointly, is provided with in the cavity:

the top of the C-shaped magnetic circuit is in contact with the inner surface of the end cover, and two ends of the bottom opening of the C-shaped magnetic circuit are connected with the groove;

the two permanent magnets are respectively arranged on the inner side surfaces of two ends of the bottom opening of the C-shaped magnetic circuit;

the two channel side walls are symmetrically arranged between the two permanent magnets and form the thickness of the fluid channel;

the channel outer ring is arranged between the two channel side walls, two sides of the channel outer ring are in contact with the inner side face of the end cover, and a second electrode is arranged on the channel outer ring; and the second electrode is on the straight line section below the fluid channel;

the inner wall of the channel is arranged in the outer ring of the channel, and forms a fluid channel together with the two channel side walls and the outer ring of the channel, and the fluid channel is filled with a conductive fluid; a first electrode is arranged on the channel inner ring; and the first electrode is on a straight segment below the fluid channel.

The magnetohydrodynamic line vibration sensor is also characterized in that the axes of the base, the end cover, the C-shaped magnetic circuit, the two permanent magnets, the two channel side walls, the channel outer ring and the channel inner ring of the metal shell are vertical to the axis of the magnetohydrodynamic line vibration sensor in the measuring direction.

The two permanent magnets are distributed on two sides of the fluid channel, the magnetic field distribution is uniform, and the remanence direction is in the vertical direction of the measuring direction, so that a vertical magnetic field environment is formed.

The first electrode and the second electrode respectively output potential signals for measuring the potential difference between the channel outer ring and the channel inner ring.

The invention has the following advantages and beneficial effects:

1. the invention innovates the principle of the vibration sensor, and adopts the magnetohydrodynamics effect (MHD) to be different from the novel linear vibration sensor of the traditional vibration sensors such as a piezoresistive vibration sensor, a piezoelectric vibration sensor and the like, so that the sensor has the advantages of wide band, low power consumption, low noise, small volume, light weight, high reliability, high strength, long service life and the like; the blank of the current magnetohydrodynamic linear vibration sensor in China is made up.

2. The invention is based on the magnetohydrodynamics electromagnetic induction principle, uses the conductive fluid material with good fluidity and excellent conductivity, utilizes the fluid fluidity and the principle that the channel wall and the magnetic field area generate relative motion and cuts the magnetic induction line to generate motional electromotive force to detect the line vibration information, is different from the traditional line vibration sensor, and has the characteristics of high reliability, high strength and long service life because no solid moving part exists and no mechanical abrasion exists in the fluid motion measurement;

3. the structure adopted in the invention is a runway-type structure, the base of the shell forms a groove with a concave inner part, so that the C-shaped magnetic circuit, the permanent magnet, the channel side wall and the second electrode which are contacted with the base are all embedded in the groove, the structure is very stable, and the axes of the symmetry axes of the base of the shell, the end cover and the C-shaped magnetic circuit, the permanent magnet, the channel side wall, the channel outer wall and the channel inner wall in the shell are all vertical to the axis of the sensitive shaft of the magnetohydrodynamic line vibration sensor, so that the sensitivity of quadrature axis vibration is greatly reduced, and the sensor can stably work under strong impact and other severe environments;

4. the invention mainly utilizes the fluidity and the conductivity of the fluid, realizes the test of the line vibration by the electromagnetic induction principle that the fluid cuts the magnetic induction line to generate electromotive force in the movement process, and devices such as a capacitor and the like which have larger influence on the bandwidth of the sensor do not exist in the fluid, the bandwidth of the preceding-stage sensor theoretically has no upper limit, and the upper limit of the bandwidth of the whole system is only determined by the filtering link of the signal processing circuit, so the bandwidth is very large;

5. the conductive fluid in the preceding-stage sensor is filled in the fluid channel, when the sensor vibrates along with a measured piece, the magnetic induction line is cut through relative motion to generate electromotive force, the conductive fluid and the channel do not need power supply and are directly output through the positive electrode and the negative electrode, no power consumption device is arranged in the sensor, and only a subsequent signal processing circuit needs power supply, so that the performance of low power consumption is realized;

6. the effective width of the fluid channel only needs mm magnitude, the magnetic circuit design follows the principle of minimum magnetic resistance, and the reasonable selection of the material of the part is combined, when the sizes of the C-shaped magnetic circuit and other parts are designed, the maximum magnetic field intensity can be obtained with a smaller size, so that the greater sensitivity of the sensor is obtained, and an obvious output signal is obtained.

Drawings

FIG. 1 is a front cross-sectional view of a magnetohydrodynamic wire vibration sensor of the present invention;

FIG. 2 is a side cross-sectional view of a magnetohydrodynamic wire vibration sensor of the present invention;

FIG. 3 is an external profile view of a magnetohydrodynamic wire vibration sensor of the present invention;

reference numbers in the figures: 1. a metal housing end cap; 2. a groove; 3. a metal housing base; 4. a magnetic circuit; 5. a first permanent magnet 6, a second permanent magnet; 7. a right channel side wall; 8. a left channel side wall; 9. a second electrode; 10. a channel outer ring; 11. conductive fluid 12, inner ring of channel; 13. a first electrode; 14. an axis of symmetry.

Detailed Description

In this embodiment, a magnetohydrodynamic wire vibration sensor includes an outline design of the sensor as shown in fig. 3, and a magnetic circuit design inside a housing as shown in fig. 1 and 2, where the metal housing is composed of a base 3 and an end cover 1, and a groove 2 is formed inside the base 3 for fixing each component in contact therewith. The metal shell is a cuboid, and is convenient to process. The base 3 and the end cover 1 of the metal shell are made of soft magnetic materials with high saturation magnetic flux density, and iron-cobalt alloy or iron-nickel alloy can be selected, so that the influence of the internal magnetic circuit of the sensor on surrounding devices is prevented, and the influence of external electromagnetic interference on the internal sensing part of the shell is avoided. Recess 2 forms a cavity jointly with end cover 1 is inside, is provided with in the cavity:

the top of the C-shaped magnetic circuit 4 is contacted with the inner surface of the end cover 1, and the two ends of the bottom opening of the C-shaped magnetic circuit are connected with the groove 2. The C-shaped magnetic circuit 4 is made of soft magnetic material with high saturation magnetic flux density, so that the influence of external electromagnetic interference can be secondarily shielded, meanwhile, a pair of permanent magnets can be matched to form a closed magnetic circuit, and the design of the C-shaped structure follows the minimum principle of the magnetic circuit, so that the sensor can obtain the magnetic field condition as large as possible in a limited space.

The pair of permanent magnets comprises a first permanent magnet 5 and a second permanent magnet 6 which are respectively arranged on the inner side surfaces of two ends of the bottom opening of the C-shaped magnetic circuit 4. The magnetic pole on one side is connected with the inner wall of the magnetic circuit, the magnetic pole on the other side is contacted with the outer wall of the corresponding side wall of the fluid channel, and the bottom is embedded into the groove 2, so that the magnetic leakage condition of the magnetic field can be reduced, and the sensitivity of the sensor is improved. The first permanent magnet 5 and the second permanent magnet 6 should be made of permanent magnet materials capable of providing strong magnetic fields, and neodymium iron boron is selected as a preferred embodiment. The permanent magnet is in a cuboid shape, so that the permanent magnet is easy to form a magnetic field environment which is vertical to the measuring direction and uniform and vertical. The magnetic pole directions of the first permanent magnet 5 and the second permanent magnet 6 are consistent, the north pole face of the first permanent magnet 5 can be selected to be tightly attached to the inner wall of the C-shaped magnetic circuit 4, the south pole face of the second permanent magnet 6 is placed in a mode of being tightly attached to the inner wall of the C-shaped magnetic circuit 4, the south pole face of the first permanent magnet 5 can be further selected to be tightly attached to the inner wall of the C-shaped magnetic circuit 4, correspondingly, the second permanent magnet 6 is placed in a mode of tightly attaching the north pole face to the inner wall of the C-shaped magnetic circuit 4, and different placing modes only influence the polarity.

The two channel side walls comprise a right channel side wall 7 and a left channel side wall 8, the outer side of the right channel side wall 7 is in contact with the second permanent magnet 6, the outer side of the left channel side wall 8 is in contact with the first permanent magnet 5, the bottom of the left channel side wall is embedded into the groove 2, and the upper side of the left channel side wall is in contact with the inner wall of the metal shell end cover 1 to form the side walls forming the fluid channel, namely the two channel side walls are symmetrically arranged between the two permanent magnets and form the thickness of the fluid channel; the magnetic field is uniformly distributed on two sides of the fluid channel, and the remanence direction is in the vertical direction of the measuring direction, so that a vertical magnetic field environment is formed. The right channel side wall 7 and the left channel side wall 8 are in a runner shape, and the structure is smaller in flow resistance when fluid flows compared with a rectangular structure, and is more convenient to process compared with a circular structure. The right channel side wall 7 and the left channel side wall 8 are made of insulating non-magnetic-conducting materials, polycarbonate or organic glass can be selected, and therefore influence on distribution of electric potential on the electrodes is avoided.

And the channel outer ring 10 is arranged between the right channel side wall 7 and the left channel side wall 8, the outer side of the channel outer ring is in contact with the inner side face of the end cover 1, and a second electrode 9 is arranged at the lower wall of a straight line section at the bottom of the channel type fluid channel outer ring 10.

The channel inner ring 12 is arranged between the right channel side wall 7 and the left channel side wall 8, forms a fluid channel 11 together with the channel outer ring 10, and is filled with a conductive fluid in the fluid channel 11; the fluid channel 11 is connected by epoxy resin glue, so that the conductive fluid 11 can be effectively prevented from overflowing. The upper wall of the straight line section at the bottom of the channel inner ring 12 is provided with a first electrode 13. Except that the upper wall and the lower wall of the bottom straight channel section are good conductors, the rest parts are all made of insulating non-magnetic conducting materials, so that the potential distribution is not influenced, and the mutual coupling influence between two electromagnetic signals can be effectively reduced. The fluid channel is filled with a conductive fluid 11 with low viscosity and high magnetic permeability, and as a preferred embodiment, the conductive fluid 11 is gallium indium tin.

The two sides of the channel outer ring 10 and the channel inner ring 12 are connected with the right channel side wall 7 and the left channel side wall 8 to form an inner ring and an outer ring of the fluid channel. The outer and inner channel rings 10, 12 are both race-shaped and thus more easily fit the right and left

channel side walls

7, 8. The materials of the channel outer ring 10 and the channel inner ring 12 are the same as those of the right channel side wall 7 and the left channel side wall 8, and the insulating non-magnetic-conducting materials are selected.

The material of the first electrode 13 and the second electrode 9 should be selected to be a good conductor, such as a metallic copper material, or a metallic silver material. The high conductivity and the low resistance are required to improve the voltage value of the output signal. The first electrode 13 and the second electrode 9 respectively output potential signals for measuring the potential difference E between the channel outer ring 10 and the channel inner ring 12.

The axis 14 of the symmetry axis of the base 3, the end cover 1, the C-shaped magnetic circuit 4, the first permanent magnet 5, the second permanent magnet 6, the right channel side wall 7, the left channel side wall 8, the channel outer ring 10 and the channel inner ring 12 of the metal shell is perpendicular to the measuring direction of the magnetic fluid linear vibration sensor, so that the vibration sensitivity in the cross-axis direction can be effectively reduced, and the sensitivity of the sensor is improved.

C shape magnetic circuit 4 opening both ends, first permanent magnet 5, second permanent magnet 6, right side passageway lateral wall 7, left side passageway lateral wall 8 and second electrode 9 all imbed by the shell base 3 in the recess 2, make the cooperation between each part of sensor inseparable like this, the structure is more stable and compact, improves space utilization.

In this embodiment, assuming that the magnetic field is uniform, and the upper and lower electrodes are respectively at equal potentials, the current and potential in the fluid cavity will be uniformly distributed, and the working principle of the magnetohydrodynamic linear vibration sensor is as follows:

the working principle of the magnetohydrodynamic linear vibration sensor is based on the magnetohydrodynamic effect MHD, namely the coupling effect of a velocity field and a magnetic field of a conductive fluid. The conductive fluid 11 is filled in the runway-type fluid channel, the runway-type fluid channel is only conductive at the upper wall and the lower wall of the bottom straight channel section, and the rest parts are all insulated. The straight line section at the bottom of the runway type fluid channel is in a strong magnetic field. When a line vibration signal alpha is input from the outside in the direction of the sensitive axis of the magnetohydrodynamic line vibration sensor, the first permanent magnet 5, the second permanent magnet 6 and the fluid channel generate linear displacement relative to the inertial space, and the conductive fluid 11 has low viscosity and large inertia, so that relative motion is generated between the conductive fluid 11 and the magnetic fields generated by the first permanent magnet 5 and the second permanent magnet 6, the conductive fluid 11 cuts a magnetic induction line, and the relative speed of the conductive fluid 11 is V_αAn electromotive force E is generated between the first electrode 13 and the second electrode 9, which electromotive force E is dependent on α and the magnetic induction B, where E ═ V_αAnd (B) is multiplied by. And the input line vibration information is obtained after the processing of the detection system.

In the testing process, the designed sensor is installed on a fixing tool through a screw, and the fixing tool is fixedly connected to the linear vibration test through the screw after being connected with the designed sensor through the screw. The wire vibration table provides vibration signals to drive the designed sensor to move and output test signals. The first electrode 13 and the second electrode 9 of the designed sensor are respectively connected with a data acquisition card to acquire signals, the acquired data are transmitted to a computer, and the computer displays the test data in real time.

Claims

1. A magnetic fluid dynamic linear vibration sensor with a runway-type structure comprises a metal shell and is characterized in that the metal shell is composed of a base (3) and an end cover (1), and a groove (2) is arranged in the base (3); recess (2) and end cover (1) are inside to form a cavity jointly, are provided with in the cavity:

the top of the C-shaped magnetic circuit (4) is in contact with the inner surface of the end cover (1), and two ends of an opening at the bottom of the C-shaped magnetic circuit (4) are connected with the groove (2);

the two permanent magnets are respectively arranged on the inner side surfaces of two ends of the bottom opening of the C-shaped magnetic circuit (4);

the two channel side walls are symmetrically arranged between the two permanent magnets and form the thickness of the fluid channel (11);

the channel outer ring (10), the channel outer ring (10) is arranged between the two channel side walls, two sides of the channel outer ring (10) are in contact with the inner side face of the end cover (1), and the channel outer ring (10) is provided with a second electrode (9); and the second electrode (9) is on a straight section below the fluid channel (11);

the inner channel ring (12), the inner channel wall (12) is arranged in the outer channel ring (10), and forms a fluid channel (11) together with the two channel side walls and the outer channel ring (10), and the fluid channel (11) is filled with a conductive fluid; a first electrode (13) is arranged on the channel inner ring (12); and the first electrode (13) is on a straight section below the fluid channel (11).

2. A magnetohydrodynamic wire vibration sensor according to claim 1, characterized in that the axis of the base (3), end cap (1), C-shaped magnetic circuit (4), two permanent magnets, two channel side walls, channel outer ring (10) and channel inner ring (12) of the metal housing is perpendicular to the axis of the measuring direction of the magnetohydrodynamic wire vibration sensor.

3. A magnetohydrodynamic line vibration sensor as claimed in claim 1, wherein the two permanent magnets are distributed on both sides of the fluid channel and the magnetic field is uniformly distributed with the remanence direction in a direction perpendicular to the measuring direction, thereby forming a perpendicular magnetic field environment.

4. A magnetohydrodynamic wire vibration sensor according to claim 1, characterized in that the first electrode (13) and the second electrode (9) each output a potential signal for measuring the potential difference between the outer channel ring (10) and the inner channel ring (12).