CN116125528A

CN116125528A - Speed sensor

Info

Publication number: CN116125528A
Application number: CN202211255813.6A
Authority: CN
Inventors: 易爱华; 周晓
Original assignee: Shanghai Chengkan Information Technology Co ltd
Current assignee: Shanghai Chengkan Information Technology Co ltd
Priority date: 2022-09-14
Filing date: 2022-10-13
Publication date: 2023-05-16

Abstract

The embodiment of the specification discloses a speed sensor, is two magnetism structures, speed sensor includes: a housing; the shell is of a cylindrical structure, and spring diaphragms are respectively arranged at an upper end cover and a lower end cover in the shell; the coil framework is arranged between the two spring diaphragms; at least two magnetic rings which are symmetrically arranged are arranged in the coil framework along the axial direction, and the magnetization direction of each magnetic ring is along the radial direction; and the outer side of the coil framework is provided with an upper coil and a lower coil which are opposite in winding direction and are connected in series with each other at positions corresponding to the two magnetic rings. The speed sensor provided by the specification is high in sensitivity.

Description

Speed sensor

Technical Field

The invention relates to the field of micro-motion exploration, in particular to a speed sensor.

Background

Compared with the traditional geophysical exploration method, the micro-motion exploration adopts earth environment noise or artificial noise, can effectively measure shear wave velocity at a large number of sites in a dense urban area, is a passive method, is non-invasive and environment-friendly, has great potential as a field investigation tool, is expected to become an important noninvasive exploration method for identifying advanced geological forecast of stratum velocity structure, and has wide application prospect.

Magneto-electric low frequency speed sensors are one of the most effective methods for measuring ground movement. Because the micro-motion exploration adopts natural noise, the signal is weaker, the micro-motion exploration is particularly easy to be influenced by strong surrounding vibration noise, the magnitude of a micro-vibration event is very small (namely-3-1 MW) under normal conditions, the effective frequency of the micro-vibration event can be between hundreds of hertz, and the micro-vibration event has higher requirements on the weak signal detection capability of the instrument. Sensitivity is an important indicator reflecting the sensor's vibration signal, and in recent years, the production of a low-frequency sensor with reliable sensitivity is one of the main targets of scientific researchers.

The conventional low-frequency speed sensor mainly comprises a coil, a coil framework, a spring diaphragm, a permanent magnet and magnetic shoes, wherein the permanent magnet is axially magnetized, and the magnetic shoes made of industrial pure iron are adsorbed on the upper side and the lower side of the permanent magnet and used for changing the direction of magnetic induction lines so as to enable the magnetic induction lines to diverge from the vertical direction to the horizontal direction.

However, conventional low frequency speed sensors have low sensitivity and generally require increased permanent magnet magnetism, volume or increased coil diameter, number of turns to increase in order to increase sensitivity, which undoubtedly makes the sensor mass and volume excessive. There is therefore a need for a speed sensor with a high sensitivity.

Disclosure of Invention

An object of the embodiments of the present specification is to provide a speed sensor with high sensitivity.

The present description embodiment provides a speed sensor, which is a dual magnetic structure, comprising: a housing; the shell is of a cylindrical structure, and spring diaphragms are respectively arranged at an upper end cover and a lower end cover in the shell; the coil framework is arranged between the two spring diaphragms; at least two magnetic rings which are symmetrically arranged are arranged in the coil framework along the axial direction, and the magnetization direction of each magnetic ring is along the radial direction; and the outer side of the coil framework is provided with an upper coil and a lower coil which are opposite in winding direction and are connected in series with each other at positions corresponding to the two magnetic rings.

In one embodiment, the device further comprises two symmetrically arranged copper gaskets, wherein one copper gasket is arranged between the upper magnetic ring and the upper end cover, and the other copper gasket is arranged between the lower magnetic ring and the lower end cover.

In one embodiment, the contact surface of the copper gasket and the end cover has a concave feature, and the contact surface of the copper gasket and the magnetic ring has a boss which is matched with the inner diameter of the magnetic ring.

In one embodiment, a magnetic conduction shaft is arranged between the two magnetic rings; and the magnetic conduction shaft, the copper gasket and the magnetic ring are coaxially nested.

In one embodiment, two ends of the magnetic conduction shaft are matched with the inner diameter of the magnetic ring, and the outer diameter of the middle part of the magnetic conduction shaft is larger than the outer diameter of the two ends of the magnetic conduction shaft.

In one embodiment, the coil is a bifilar coil; the enamelled wires of the upper coil and the lower coil are respectively connected with the upper spring diaphragm and the lower spring diaphragm through soldering tin, and the two coils are connected at the middle of the coil framework; the lead inside the coil framework sequentially passes through the copper gasket, the magnetic ring, the magnetic conduction shaft, the magnetic ring and the copper gasket, and is led out from the middle part of the copper gasket.

In one embodiment, the upper end cap is provided with pins for deriving signals; an insulating layer is further arranged between the upper end cover and the copper gasket.

In one embodiment, a yoke is disposed adjacent to the upper end cap and the lower end cap.

In one embodiment, the outer diameter of the middle part of the magnetic conduction shaft is 8mm, the outer diameters of the two ends of the magnetic conduction shaft are 5mm, and the inner diameter of the magnetic ring is 5mm correspondingly.

In one embodiment, the magnetization directions of the upper and lower magnetic rings are opposite.

Through the implementation mode, the axial magnetizing column in the traditional magnetoelectric speed sensor is abandoned, the radial magnetizing magnetic ring is selected to generate a magnetic field, and the structure improves the magnetic field intensity and uniformity in the coil movement space and improves the output voltage and sensitivity of the sensor under the condition of not increasing the complexity and total volume of the system. The embodiment provided by the application avoids the problems of overlarge sensor quality and volume, and saves production materials; compared with the additional introduction of other structures or technologies, the design has lower design and production cost and stronger practicability in engineering.

Drawings

In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present description, and that other drawings may be obtained according to these drawings without inventive effort to a person skilled in the art.

FIG. 1 is a schematic diagram of a dual magnetic speed sensor provided herein;

FIG. 2 is a simplified model schematic of a dual magnetic speed sensor provided herein;

FIG. 3 is a schematic diagram of an equivalent spring-mass-damper system provided herein;

FIG. 4 is a schematic diagram of a magnetization direction of a radial magnetizing magnetic ring provided in the present specification;

FIG. 5 is a schematic diagram of the induced current generated in a single turn coil provided herein;

FIG. 6 is a schematic diagram of the internal magnetic field distribution vector of a dual magnetic sensor provided in the present specification;

fig. 7 is a schematic diagram of coaxial assembly of a magnetic ring, a copper gasket and a magnetic conductive shaft provided in the present specification;

FIG. 8 is a schematic diagram of the internal circuit connections of a sensor provided in the present specification;

FIG. 9 is a schematic diagram of the magnetic field generated by an induced current provided herein;

FIG. 10 is an overall cross-section and internal dimensional view of a sensor provided herein;

FIG. 11 is a graph showing frequency characteristics at different sensitivities provided herein;

FIG. 12 is a schematic diagram of the internal magnetic field strength distribution of a dual magnetic speed sensor provided herein;

FIG. 13 is a graph showing the magnetic flux density contrast of the working air gap for two magnetic field configurations provided herein;

FIG. 14 is a graph of simulation versus measurement of magnetic field strength for two sensors provided herein;

FIG. 15 is a schematic diagram of waveform characteristic data of a DC excitation method according to the present disclosure;

description of the drawings: 10. the device comprises an upper spring diaphragm, 20, a coil, 30, a magnetic conduction shaft, 40, a copper gasket, 50, a shell, 60, an upper end cover, 70, a magnetic ring, 80, a coil framework, 90, a lower spring diaphragm, 100, a lower end cover, 110, an object to be tested, 120, an inertial body, 130, a damper, 140, soldering, 150 and an enameled wire.

Detailed Description

The technical solutions of the embodiments of the present specification will be clearly and completely described below with reference to the drawings in the embodiments of the present specification, and it is apparent that the described embodiments are only some embodiments of the present specification, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments herein should be considered as falling within the scope of the present application.

The speed sensor that this specification provided is two magnetic structure, speed sensor includes: a housing 50; the shell 50 is of a cylindrical structure, and spring diaphragms are respectively arranged at the upper end cover 60 and the lower end cover 100 in the shell 50; a bobbin 80, the bobbin 80 being disposed between two of the spring diaphragms; at least two magnetic rings 70 symmetrically arranged are arranged in the coil framework 80 along the axial direction, and the magnetization direction of the magnetic rings 70 is along the radial direction; the outer side of the coil frame 80 is provided with an upper coil 20 and a lower coil 20 which are wound in opposite directions and are connected in series with each other, corresponding to the positions of the two magnetic rings 70.

In this embodiment, the speed sensor is a magneto-electric speed sensor based on a dual magnetic model. In this embodiment, the magnetic ring 70 is a permanent magnet. The permanent magnet and the coil 20 wound on the former constitute an electromagnetic induction system.

In one embodiment, the device further comprises two symmetrically arranged copper gaskets 40, wherein one copper gasket 40 is arranged between the upper magnetic ring 70 and the upper end cover 60, and the other copper gasket 40 is arranged between the lower magnetic ring 70 and the lower end cover 100.

In one embodiment, a magnetic conductive shaft 30 is disposed between two of the magnetic rings 70; the magnetic shaft 30 and the copper gasket 40 are coaxially nested with the magnetic ring 70.

In one embodiment, the contact surface of the copper gasket 40 and the end cap has a concave feature, and the contact surface of the copper gasket 40 and the magnetic ring 70 has a boss that mates with the inner diameter of the magnetic ring 70. The copper gasket 40 may be tightly attached to the upper and lower end caps 100 and the magnetic ring 70, and the structure is stable.

Please refer to fig. 1. In this embodiment, the magnetic ring 70, the magnetic shaft 30, the spring diaphragm and the housing 50 may form a mechanical system, and the magnetic field generated by the magnetic ring 70 is enclosed in the housing by the external housing. The coil 20 is connected with the shell 50 through a spring diaphragm and is positioned in a magnetic field between the magnetic ring 70 and the shell 50 to form an inertial body 120 which moves relative to the magnetic ring 70 and the shell 50, and the bottom of the sensor is coupled with the ground. The magnetic rings 70 are magnetized along the radial direction, the magnetizing directions of the upper magnetic ring 70 and the lower magnetic ring 70 are opposite, the middle part of the upper magnetic ring 70 can be connected by one magnetic conduction shaft 30, and the outer ends of the upper magnetic ring 70 and the lower magnetic ring 70 are coaxially provided with gaskets made of pure copper, namely the copper gaskets 40, so as to play roles of fixing and conducting. Please refer to fig. 2, which is a simplified model of a dual magnetic speed sensor.

In this embodiment, the dual magnetic speed sensor operates on principle. Specifically, the magneto-electric low-frequency sensor adopts a moving coil structure. Its basic working principle is electromagnetic induction. Referring to fig. 3, the sensor can be modeled as a simple spring-mass-damper 130 oscillator. Acceleration of the sensor housing 50 applies an inertial force to the magnetic ring 70. When the object vibrates, the magnetic ring 70 is fixed in the sensor housing, and vibrates with the object together with the housing, and the coil 20 assembly is connected with the housing through an elastic diaphragm and can move back and forth in the vertical direction in the sensor. Due to inertia, when the vibration frequency of an object is higher and higher, the coil 20 assembly keeps stationary in absolute space without keeping up with the vibration of an external object, so that the coil 20 and the magnet perform relative motion, and the cutting magnetic induction lines output induced voltages. The relative motion between the coil 20 and the housing is an objective reflection of the actual ground motion function. Compared with the acceleration sensor, the displacement of the speed sensor output by the speed sensor is also deduced mainly through one integration, so that the twice integration error caused by the drift of the acceleration sensor in a low-frequency region is avoided.

The induced voltage U in the windings of the coil 20 satisfies the following relation:

U＝B _i L ₀ N _i v ₀ #(1)

wherein B is _i For working air gap induction (T), L ₀ For the average length (m), N of each turn of the coil 20 _i V is the number of turns of coil 20 winding in the working air gap ₀ Is the vibration velocity (m/s) of the vibrating object.

In this embodiment, at least two magnetic rings 70 symmetrically arranged along the axial direction are disposed inside the coil bobbin 80, and the magnetization direction of the magnetic rings 70 is along the radial direction;

referring to fig. 4, fig. 4 is a schematic diagram of magnetization of a radially magnetized magnetic ring 70. One color represents the S pole and the other color represents the N pole. Arrows indicate the current direction at different surfaces of the magnetic ring 70,

indicating the direction of magnetization. The radially magnetized magnetic field is generated by molecular currents on the upper and lower surfaces of the magnetic ring 70The current direction is opposite.

Let N be the number of coils 20 in the dual magnetic speed sensor that move relative to the magnetic ring 70. The output voltage is

Where epsilon represents the output voltage value, N is the number of coils 20 in the working air gap,

representing the voltage generated by the single turn coil 20.

Referring to fig. 5, fig. 5 is a schematic diagram of the induced current generated in the single turn coil 20. A small section of a turn of the coil 20 is randomly selected for analysis. The direction of the magnetic field that produces the greatest induced current in the coil 20 is verified. As shown in FIG. 5, it is assumed that magnetic induction line cutting coils 20, t of different directions are provided ₀ For initial time, x ₀ Is the initial position of the current; at time t ₁ Reach position x ₁ 。S ₁ And S is ₂ Representing the two end faces, S, of the small coil 20 ₃ Indicating the side surfaces thereof. S is S ₁ The director of the surface is k ₁ ，S ₃ The director of the surface is k ₂ The magnetic flux in the coil 20 is

∫B·dS＝∫B·k ₁ dS ₁ +∫B·k ₁ dS ₀ +∫B·k ₂ dS ₃ ＝0#(3)

The side surfaces may be further written as

S ₃ ＝2πrΔx#(4)

Where r denotes an end face radius and Δx is a coil 20 length. When time (t ₁ -t ₀ ) Near zero, Δx may be written as dx.

The output voltage can be expressed as

ε＝-(∫B·k ₁ dS ₀ +∫B·k ₁ dS ₁ )#(5)

Substituting equations (3) and (4) into equation (5) can obtain an expression for generating induced electromotive force in the coil 20

The sensitivity is maximized when the induced electromotive force generated in the coil 20 is maximized. In this case, sinθ=1. The direction of the magnetic field in the air gap is perpendicular to the direction of movement of the coil 20. Furthermore, there is no component in the x direction. For a magneto-electric speed sensor, when radial magnetizing magnet ring 70 is selected, there is a minimum magnetic field x-direction component (zero) to achieve the optimal solution.

Referring to fig. 6, fig. 6 is a vector diagram of the distribution of the magnetic field inside the dual magnetic sensor, it can be seen that the upper and lower magnetic rings 70 are radially magnetized, the magnetizing directions are opposite, and the magnetic induction lines form a loop between the upper and lower magnetic rings 70, the upper and lower air gaps, the magnetic conductive shaft 30 and the housing 50, so that the electromotive force output can be improved to the greatest extent by the design, and the sensitivity of the sensor is further improved.

Referring to fig. 7, fig. 7 is a schematic diagram illustrating the coaxial assembly of the magnetic ring 70, the copper pad 40 and the magnetic shaft 30. The magnetic conductive shaft 30 is made of pure industrial iron having a low magnetic reluctance rate. Thus, the main advantage of the shaft is excellent magnetic permeability. Fig. 7 shows the structure of the magnetic conductive shaft 30 and the combination relation with other components. The magnetic shaft 30 is not simply cylindrical, but is designed to have a thick middle and thin ends, so that the magnetic ring 70 is secured to the two ends of the magnetic shaft 30 under attractive force. The magnetic ring 70 is coaxially nested with the magnetic shaft 30 and the copper gasket 40, and the copper gasket 40 is also fixed under the extrusion of the upper and lower end caps 100 and the magnetic ring 70. Gaps exist between the two ends of the magnetic conduction shaft 30 and the copper gaskets so as to ensure that the end surfaces of the magnetic conduction shaft and the copper gaskets can form tight combination.

In one embodiment, the outer diameter of the middle part of the magnetic conductive shaft 30 is 8mm, the outer diameters of the two ends of the magnetic conductive shaft 30 are 5mm, and the inner diameter of the magnetic ring 70 is 5mm.

In one embodiment, the coil 20 is a bifilar coil 20; wherein, the enamelled wires of the upper and lower coils 20 are respectively connected with the upper and lower spring diaphragms by soldering tin, and the two coils 20 are connected at the middle of the coil frame 80; the wires inside the coil bobbin 80 sequentially pass through the copper gasket 40, the magnetic ring 70, the magnetic shaft 30, the magnetic ring 70, and the copper gasket 40, and are led out from the middle of the copper gasket 40.

In one embodiment, the upper end cap 60 is provided with pins for deriving a signal; an insulating layer is further arranged between the upper end cover and the copper gasket.

Referring to fig. 8, the circuit loop is mainly composed of the upper and lower copper shims, the magnetic ring 70, the spring diaphragm, the magnetic shaft 30, the coil bobbin 80, and the coil 20. Referring to fig. 8, two common circuit loops are depicted. It should be noted that these two loops do not cancel each other out, but according to the respective directions, the signal is finally derived through the pins on the upper end cap 60, satisfying the linear superposition relationship. The enameled wires of the upper and lower coils 20 are respectively connected with the upper and lower spring diaphragms by soldering tin outside the coil framework 80, and the upper and lower coils 20 are connected by enameled wires. Inside the coil frame 80, signals sequentially pass through the copper gasket 40, the magnetic ring 70, the magnetic conductive shaft 30, the magnetic ring 70 and the copper gasket 40, are led out from the middle of the copper gasket 40, and signals at the other position are led out from the spring diaphragm. An insulating layer is added between the upper spring diaphragm and the copper gasket to prevent short circuit.

In one embodiment, the magnetization directions of the upper and lower magnetic rings 70 are opposite.

Referring to fig. 9, the winding of the coil 20 has the following characteristics: the upper and lower groups are opposite in winding direction and are mutually connected in series, and the design has the following advantages: (1) the magnetic fields in the upper working air gap and the lower working air gap are opposite in direction, so that the coils 20 are wound oppositely to generate induced electromotive forces with the same direction, and the enhancement effect is achieved; (2) according to maxwell's equations, when the coil 20 and the magnetic field move relatively, the magnetic field is excited in space by the changing circuit except for the induced current in the coil 20, and the magnetic field generated by the permanent magnet is disturbed. By designing two groups of coils 20 with opposite winding directions, magnetic fields with the same size and opposite directions can be excited in space to cancel each other out, and the anti-interference capability of the system is improved.

In one embodiment, a yoke is provided near the upper end cap 60 and the lower end cap 100.

In the present embodiment, the yokes are installed near the upper and lower end caps 100 to form a totally enclosed structure, and the magnetic induction intensity in the air gap is improved by reducing the leakage flux, thereby improving the sensitivity.

By the above embodiment, the axial magnetizing column in the conventional magneto-electric speed sensor is abandoned, and the radial magnetizing magnetic ring 70 is selected to generate the magnetic field, so that the structure improves the magnetic field intensity and uniformity in the moving space of the coil 20 and improves the output voltage and sensitivity of the sensor under the condition of not increasing the structural complexity and total volume of the system. The embodiment provided by the application avoids the problems of overlarge sensor quality and volume, and saves production materials; compared with the additional introduction of other structures or technologies, the design has lower design and production cost and stronger practicability in engineering.

In the case of earth pulse detection, the sensitivity of the magneto-electric speed sensor is usually improved by increasing the volume of the coil 20, the magnetism or the diameter and number of turns of the coil 20, but the volume of the sensor is correspondingly increased; under the condition of introducing other technologies or structures, the design and operation complexity is greatly improved, and the wide use in engineering is not facilitated.

Through the implementation mode, the double-magnetic structure is adopted, so that stray magnetic field components in an air gap are reduced, the strength of an effective magnetic field is improved, the range of a uniform magnetic field is enlarged, the output voltage of the sensor is improved under the condition that the volume of the sensor and the complexity of a system are not increased, and the sensitivity is improved. The speed sensor provided by the application can be used for all magnetoelectric devices adopting a magnetic field structure.

The novel double-magnetic speed sensor has the advantages that magnetic induction lines directly enter a working air gap from magnetic steel, the effective magnetic field proportion perpendicular to a coil 20 in the working air gap is improved, the sensitivity is further improved, and the weak signal detection capability of the sensor is improved. Experiments prove that the magnetic induction intensity is increased by 29.9 percent under the condition of the same magnetic steel volume, and the sensitivity is increased by 23.9 percent, so that the purpose of fully utilizing materials is achieved on the basis of ensuring the unchanged structural complexity.

Sensitivity is the ratio of the output voltage value of the sensor to the vibration speed received by the sensor, and represents the capability of the magnetoelectric sensor to convert a received signal into a voltage output signal, so that the sensitivity is one of the most important technical indexes of the low-frequency sensor.

The sensitivity of the open loop low frequency sensor meets the following conditions: g=bl. Where G is the sensor sensitivity, B is the magnetic induction in the sensor, and l is the effective length of the wire of the coil 20. The frequency characteristic curves at different sensitivities were plotted as shown in fig. 11, with the optimal damping ratio of 0.707 and the natural frequency of 4.5 Hz. When the sensitivity is sequentially g=5, g=10, g=20, g=50 and g=100, the output signal phase of the sensor is unchanged, and the output signal amplitude and the sensitivity are positively correlated. As a key indicator of the ability of the sensor to receive a weak vibration signal, the sensitivity should be higher as the intensity of the vibration signal is lower. The sensitivity should be increased as much as possible in the sensor design, so that the received signal is easier to distinguish from noise.

For the input signals with the same amplitude, the higher the sensitivity is, the larger the output signal of the magnetoelectric vibration sensor is, and the change of the sensitivity has no influence on the phase frequency characteristic. Sensitivity is a key indicator for representing the capacity of the sensor to receive weak vibration signals, and the weaker the vibration signal to be picked up, the higher the expected sensitivity. Therefore, the sensitivity should be improved as much as possible in the sensor design to ensure that the amplitude of the received signal is within a larger range.

The conventional low-frequency speed sensor mainly comprises a coil 20, a coil framework 80, a spring diaphragm, a permanent magnet and magnetic shoes, wherein the permanent magnet is axially magnetized, and the magnetic shoes made of industrial pure iron are adsorbed on the upper side and the lower side of the permanent magnet and used for changing the direction of magnetic induction lines so as to be diverged from the vertical direction to the horizontal direction. The materials used for the parts of the dual magnetic speed sensor are shown in the following table.

Table 1 double magnetic speed sensor parts materials table

Please refer to fig. 12. The magnetic field intensity in the double-magnetic-speed sensor is simulated by using simulation software, and as can be seen from fig. 12, the magnetic field intensity in the air gap is between 450mT and 700mT, and the air gap magnetic field intensity in the non-work area is between 0 and 72 mT. The upper and lower magnetic rings 70 are radially magnetized, but the magnetizing directions are opposite, and a complete magnetic circuit is formed by the upper and lower radiation rings, the magnetic conductive shaft 30, the housing 50 and an air gap between the housing 50 and the radiation rings. Notably, the following is true. The total volume of the two magnetic rings 70 adds up to the volume of the magnetic steel in the conventional model.

Please refer to fig. 13. The left graph shows the distribution of magnetic induction lines of a double magnetic structure, the right graph shows the distribution of magnetic induction lines of a traditional structure, the left magnetic induction lines are denser and more uniformly distributed according to the graph, magnetic force lines emitted by the right are sparse, the deflection of the magnetic induction lines passing through the top of a magnetic shoe is large, and the copper ring is coaxially nested at the outer end of the double magnetic speed sensor, and the magnetic permeability is low (1.26 multiplied by 10) ^-6 H/m), high conductivity (5.96×10 ⁷ S/m), on the one hand, prevents the magnetic induction lines from returning directly from under the magnetic ring 70, and on the other hand, has an electrically conductive effect.

The embodiment of the application can also provide an experimental comparison method. In order to verify theory and simulation results, a laboratory tests the magnetic field uniformity and magnetic induction intensity of two magnetic field structures, an industrial-grade high-precision magnetic field intensity instrument is used for measuring the magnetic induction intensity of an air working air gap in combination with a Hall sensor, a sensor probe is made to cling to the outer wall of a coil 20 and axially move at a rated speed, the length of a movement path is 4cm, the movement speed is 0.8cm/s, the numerical display sizes of the magnetic field intensity instruments at different moments are recorded, images are drawn, and the magnetic field distribution conditions of the two structures are compared.

Referring to fig. 14, measurement experiment results of a conventional magnetic field structure and a sensor provided in the present application are shown. The lower two lines are measurement experimental results of the traditional magnetic field structure, and the upper two lines are measurement experimental results of the sensor provided by the application. In the figure, the abscissa represents the path in mm, the ordinate represents the magnetic induction, and the unit is mT. Experimental results show that the maximum magnetic field strength of the traditional magnetic field structure can reach 497mT, the working space is 5.2-8.4 mm, and the maximum magnetic field strength of the sensor structure provided by the application is 642mT, wherein the corresponding length of the sensor structure is 3.2 mm. The working space is 5.0 mm-9.2 mm, the corresponding length is 4.2mm, and the magnetic field is uniform. Compared with the traditional magnetic field structure, the magnetic induction intensity in the working air gap is improved by 29.18%, and the magnetic field uniformity of the whole air gap path is improved by 31.25% compared with the traditional structure. The experimental results were different from the simulation results. This may be related to material properties and processing. But the general trend is the same; the proposed new magnetic field structure has a better magnetic field strength and a more uniform magnetic field in the air gap.

The direct current excitation method is a commonly used method for testing dynamic parameters such as natural frequency, sensitivity, damping ratio and the like of the moving coil electromagnetic speed sensor.

The coil 20 of the sensor is subjected to a DC excitation applied across the sensor of a magnitude

Urging it to lift (shift) upward away from its original equilibrium position. Please refer to fig. 15. After the coil 20 of the sensor is stabilized for a period of time, once the exciting current is instantaneously disconnected, the coil 20 can perform up-down damping vibration at the original balance position, and meanwhile, a corresponding response voltage signal is output, and an oscilloscope is used for collecting and storing the output voltage waveform. According to the characteristics of the waveform (first peak A ₁ Second peak A ₂ Time T when the first voltage is 0 ₀ ) To obtain the natural frequency, sensitivity and damping coefficient of the speed sensor. The corresponding waveform data is processed on a computer.

In order to provide stable direct current with proper size, a resistor of 10KΩ is connected in series with a direct current voltage source, and the exciting current is increased by gradually increasing the output voltage of the voltage source, and compared with the existing low-frequency speed sensor with the model of PS-4.5. At 4×10 ^-4 For samplingAt intervals, 2500 sampling points are taken for sampling, and the 1250 th point is set as the sampling point.

The speed sensor voltage response satisfies the formula:

wherein G is the sensor sensitivity, I ₀ For excitation current, m is the mass of inertial body 120, η ₀ For damping coefficient omega ₀ Is the natural frequency (omega) ₀ ＝2πf ₀ )。

When y (t) =a ₁ In this case, the sensitivity of the speed sensor can be determined as

Wherein the method comprises the steps of

The excitation current can be set according to the formula

x is the displacement of the coil 20 in the vertical direction, when x is the maximum displacement x in the vertical direction _max At the time, there is a maximum excitation current

The natural frequency of the high-sensitivity magnetoelectric speed sensor and the PS sensor based on the double-magnetic model is 4.5Hz, the damping coefficient is 0.76, and the mass of the inertial body 120 is 11.3g. The sensitivity is 92V/m/s, the maximum displacement of the coil 20 is 4mm, the maximum exciting current can be calculated to be about 0.45mA, and five groups of exciting currents of 0.43mA, 0.40mA, 0.32mA, 0.28mA and 0.20mA are selected for testing, and each group is repeated three times. Group A ₁ 、A ₂ 、T ₀ Substitution into formulaThe sensitivity of the PS type sensor is 86V/m/s, the sensitivity of the DM type sensor is 114V/m/s, the damping coefficient and the frequency are in an error range of 10%, the median value is taken during calculation, and the difference between the PS type sensor and the test result is 6.5%, so that the PS type sensor is allowed.

TABLE 2 sensitivity contrast of different model speed sensors

Compared to the sensitivity of a plurality of existing speed sensors in the table above. The sensitivity of the axial magnetizing speed sensors is not equal and is lower than 100V/m/s at 28-92V/m/s, and the sensitivity of the dual-magnetic speed sensor provided by the application reaches 114V/m/s, so that the sensitivity is highest, and the sensor has larger signal output under the condition of the same weak vibration.

Although a speed sensor is described in this application, the application is not limited to what is described in the industry standard or examples, and some industry standard or implementation described in the examples using custom means or examples with modifications can achieve the same, equivalent or similar effects as the examples described above or as expected after modification. Examples of ways of data acquisition, processing, output, judgment, etc. using these modifications or variations are still within the scope of alternative embodiments of the present application.

Although the present application provides method operational steps as described in the examples or flowcharts, more or fewer operational steps may be included based on conventional or non-inventive means. The order of steps recited in the embodiments is merely one way of performing the order of steps and does not represent a unique order of execution. When implemented by an apparatus or client product in practice, the methods illustrated in the embodiments or figures may be performed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment, or even in a distributed data processing environment). The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, it is not excluded that additional identical or equivalent elements may be present in a process, method, article, or apparatus that comprises a described element.

The apparatus or module, etc. set forth in the above embodiments may be implemented in particular by a computer chip or entity, or by a product having a certain function. For convenience of description, the above devices are described as being functionally divided into various modules, respectively. Of course, when implementing the present application, the functions of each module may be implemented in the same or multiple pieces of software and/or hardware, or a module that implements the same function may be implemented by a combination of multiple sub-modules, or the like. The above-described apparatus embodiments are merely illustrative, and the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed.

Those skilled in the art will also appreciate that, in addition to implementing the controller in a pure computer readable program code, it is well possible to implement the same functionality by logically programming the method steps such that the controller is in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. Such a controller can be regarded as a hardware component, and means for implementing various functions included therein can also be regarded as a structure within the hardware component. Or even means for achieving the various functions may be regarded as either software modules implementing the methods or structures within hardware components.

The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

From the above description of embodiments, it will be apparent to those skilled in the art that the present application may be implemented in software plus a necessary general purpose hardware platform. Based on such understanding, the technical solutions of the present application may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, a mobile terminal, a server, or a network device, etc.) to perform the methods described in the various embodiments or some parts of the embodiments of the present application.

Various embodiments in this specification are described in a progressive manner, and identical or similar parts are all provided for each embodiment, each embodiment focusing on differences from other embodiments. The subject application is operational with numerous general purpose or special purpose computer system environments or configurations. For example: personal computers, server computers, hand-held or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.

Although the present application has been described by way of example, one of ordinary skill in the art will recognize that there are many variations and modifications of the present application without departing from the spirit of the present application, and that other similar structures and designs are within the scope of the present patent, such as altering the dimensions of the sensor, the material of the magnetic ring, the shape of the copper pad, etc. In addition, the design of the magnetic conduction shaft is not limited to a cylinder structure with thick middle and thin two ends, and two cylinders with thin one end and thick one end can be spliced, and the outer ends are fixed by copper rings, so that the magnetic conduction shaft is convenient to detach. It is intended that the appended claims cover such modifications and variations as fall within the true scope of this present application.

Claims

1. A speed sensor of a dual magnetic construction, the speed sensor comprising:

a housing; the shell is of a cylindrical structure, and spring diaphragms are respectively arranged at an upper end cover and a lower end cover in the shell;

the coil framework is arranged between the two spring diaphragms;

at least two magnetic rings which are symmetrically arranged are arranged in the coil framework along the axial direction, and the magnetization direction of each magnetic ring is along the radial direction;

and the outer side of the coil framework is provided with an upper coil and a lower coil which are opposite in winding direction and are connected in series with each other at positions corresponding to the two magnetic rings.

2. The speed sensor of claim 1 further comprising two symmetrically disposed copper shims, one of said copper shims being disposed between an upper said magnetic ring and said upper end cap, and the other of said copper shims being disposed between a lower said magnetic ring and said lower end cap.

3. The speed sensor according to claim 2, wherein the contact surface of the copper gasket and the end cap has a concave feature, and the contact surface of the copper gasket and the magnetic ring has a boss that mates with the inner diameter of the magnetic ring.

4. The speed sensor according to claim 2, wherein a magnetically permeable shaft is disposed between the two magnetic rings; and the magnetic conduction shaft, the copper gasket and the magnetic ring are coaxially nested.

5. The speed sensor according to claim 4, wherein the two ends of the magnetic shaft are matched with the inner diameter of the magnetic ring, and the outer diameter of the middle part of the magnetic shaft is larger than the outer diameter of the two ends of the magnetic shaft.

6. The speed sensor according to claim 4, wherein the coil is a bifilar coil; the enamelled wires of the upper coil and the lower coil are respectively connected with the upper spring diaphragm and the lower spring diaphragm through soldering tin, and the two coils are connected at the middle of the coil framework; the lead inside the coil framework sequentially passes through the copper gasket, the magnetic ring, the magnetic conduction shaft, the magnetic ring and the copper gasket, and is led out from the middle part of the copper gasket.

7. The speed sensor according to claim 6, wherein the upper end cap is provided with pins for deriving a signal; an insulating layer is further arranged between the upper end cover and the copper gasket.

8. The speed sensor according to claim 1, wherein a yoke is provided near the upper end cap and the lower end cap.

9. The speed sensor according to claim 5, wherein the outer diameter of the middle part of the magnetic conductive shaft is 8mm, the outer diameters of the two ends of the magnetic conductive shaft are 5mm, and the inner diameter of the magnetic ring is 5mm correspondingly.

10. A speed sensor according to claim 1, wherein the magnetic rings are magnetized in opposite directions.