阅读说明：本技术 一种基于巨磁阻效应的非接触角位移传感器及测量方法 (Non-contact angle displacement sensor based on giant magnetoresistance effect and measurement method ) 是由 欧阳勇 杨超 张朝坤 刘毅 胡军 于 2020-07-01 设计创作，主要内容包括：本发明公开了一种基于巨磁阻效应的非接触角位移传感器及测量方法,包括传感单元、激励单元,所述传感单元包括固定法兰、长度调节件、电路容纳件、电路板；所述电路板包括巨磁阻芯片、处理芯片,巨磁阻芯片位于电路板中间,电路板设置在电路容纳件底部中间；所述激励单元包括磁条、上壳体,所述磁条固定于上壳体底部的中间；所述传感单元安装到待测转轴的轴向外侧的固定壁上,所述激励单元安装在待测转轴的一端头部,安装后的传感单元与激励单元处于同一轴心。该基于巨磁阻效应的非接触角位移传感器具有灵敏度突出、测量精度高、使用寿命长的特点,并且防护等级更高、使用功耗更低、体积更小、价格也较便宜,适合于广泛推广应用。(The invention discloses a non-contact angle displacement sensor based on giant magnetoresistance effect and a measuring method, wherein the sensor comprises a sensing unit and an excitation unit, wherein the sensing unit comprises a fixed flange, a length adjusting piece, a circuit accommodating piece and a circuit board; the circuit board comprises a giant magnetoresistance chip and a processing chip, wherein the giant magnetoresistance chip is positioned in the middle of the circuit board, and the circuit board is arranged in the middle of the bottom of the circuit accommodating part; the excitation unit comprises a magnetic strip and an upper shell, and the magnetic strip is fixed in the middle of the bottom of the upper shell; the sensing unit is installed on the fixed wall of the axial outside of the rotating shaft to be tested, the exciting unit is installed at the head of one end of the rotating shaft to be tested, and the installed sensing unit and the exciting unit are located in the same axis. The non-contact angle displacement sensor based on the giant magnetoresistance effect has the characteristics of outstanding sensitivity, high measurement precision and long service life, is higher in protection level, lower in use power consumption, smaller in volume and lower in price, and is suitable for wide popularization and application.)

1. A non-contact angle displacement sensor based on giant magnetoresistance effect is characterized in that: comprises a sensing unit (1) and an exciting unit (2); the sensing unit (1) is of a cylindrical hollow structure, and a giant magnetoresistance chip (7) is arranged in the middle of the bottom in the top end of the sensing unit (1); the excitation unit (2) is of a cylindrical hollow structure with an opening at one end, a magnetic strip (13) is fixed at the middle position of the bottom in the sealing end of the excitation unit (2), and a rotating shaft connecting cavity (14) is arranged at the opening end of the excitation unit (2).

2. A giant magnetoresistance effect based non-contact angle displacement sensor as claimed in claim 1, wherein: the sensing unit (1) comprises a fixed flange (3), a length adjusting piece (4), a circuit accommodating piece (5) and a circuit board (6); the bottom of the fixing flange (3) is provided with three connecting and fixing holes (12), and the fixing flange (3), the length adjusting piece (4) and the circuit accommodating piece (5) are sequentially connected and fixed through the three connecting and fixing holes (12) by long screws.

3. A giant magnetoresistance effect based non-contact angle displacement sensor as claimed in claim 2, wherein: the circuit board (6) comprises a processing chip (8) and the giant magneto-resistance chip (7); the giant magnetoresistance chip (7) is connected with the processing chip (8) and the circuit board (6) through related device circuits to form a sensing circuit; a circuit accommodating cavity (9) is arranged in the middle of the bottom in the top end of the circuit accommodating part (5); the circuit board (6) is fixedly connected with the inner bottom of the top end of the circuit accommodating part (5) through screws, and the sensing circuit on the circuit board (6) is arranged in the circuit accommodating cavity (9).

4. A giant magnetoresistance effect based non-contact angle displacement sensor as claimed in claim 3, wherein: one end of the side wall of the length adjusting piece (4), which is close to the fixed flange (3), is provided with a wire outlet hole (10), and an external control cable is connected with a sensing circuit on the circuit board (6) through the wire outlet hole (10).

5. A giant magnetoresistance effect based non-contact angle displacement sensor as claimed in claim 4, wherein: all components and parts of the sensing unit (1) and the exciting unit (2) are encapsulated by packaging glue.

6. A giant magnetoresistance effect based non-contact angle displacement sensor as claimed in claim 5, wherein: the magnetic strip (13) is a rectangular, cylindrical or ring-shaped permanent magnet magnetized in the radial direction; the fixing flange (3), the length adjusting piece (4), the circuit accommodating piece (5) and the excitation unit (2) are all made of non-magnetic materials.

7. A method of measuring an angular displacement sensor according to any of claims 1 to 6, wherein: the giant magnetoresistance chip (7) is a double-shaft giant magnetoresistance chip, and when the excitation unit (2) is driven by the rotating shaft to be tested to rotate, V is generated in the directions of the X axis and the Y axis of the giant magnetoresistance chip (7) respectively_xAnd V_yThe output voltage is calculated by a processing chip (8) to obtain the value of the angular displacement α which is 0-360 degrees, and the calculation is shown in formulas ①, ② and ③:

V_x＝V₀sinα ①

V_y＝V₀cosα ②

the method comprises the following steps:

wherein, V₀An initial voltage value is input.

8. The method of measuring an angular displacement sensor of claim 7, wherein: a temperature sensor is arranged on or outside the circuit board (6), and the temperature sensor is in circuit connection with the processing chip (8); when the processing chip (8) calculates the angular displacement value, the current temperature value captured by the temperature sensor is taken into the calibration curve to be calculated together, the temperature drift of the angular displacement is corrected, and the corrected angular displacement value is output.

9. The method of measuring an angular displacement sensor of claim 8, wherein: the calibration curve adopts a zero drift curve or an output drift curve; the zero drift curve is obtained by placing an angular displacement sensor in an incubator, setting the angular displacement sensor to be in an initial 0-degree state, changing the temperature, recording output angular displacement values at different temperatures captured by the temperature sensor, obtaining a group of sequences corresponding to the temperature and the angular displacement, and fitting the sequences; the output drift curve is obtained by placing the angular displacement sensor in a temperature box, changing the temperature, rotating an excitation unit (2) of the angular displacement sensor at different temperatures, recording output angular displacement values captured by the temperature sensor at different temperatures, obtaining a group of sequences corresponding to the temperature and the angular displacement, and fitting the sequences.

Technical Field

The invention relates to the field of sensors, in particular to a non-contact angle displacement sensor based on a giant magnetoresistance effect and a measuring method.

Background

At present, in a plurality of mechanical transmission application fields such as engineering machinery, electrical equipment, aerospace and the like, a sensor is often used for detecting the rotating speed and the angle of a rotating mechanism of the sensor. The angle sensor is generally mounted on the steering mechanism, the angle sensor is connected with the signal processing circuit, and the signal processing circuit is connected with the display circuit, so that the rotating angle of the steering mechanism can be converted into a readable electric signal and displayed in the display circuit, and the accuracy and timeliness of direction control are further improved.

Most of the existing angle sensors are contact type, for example, a resistance type angle sensor, the mechanical variable resistor must be precisely aligned with the rotating shaft when being installed to ensure the accuracy of detection. In addition, since the mechanical variable resistor must be in contact with the rotating shaft, in addition to assembly errors, the service life and accuracy of the sensor are rapidly reduced due to contact wear.

In recent years, the trend of replacing contact sensors with non-contact sensors has become increasingly apparent. For example, in patent documents CN107131893A and CN201628538U, magnetic-sensing type and hall-type angle sensors are respectively invented, so that the service life and the sensing sensitivity of the sensor are greatly improved, and the volume of the sensor is also reduced. However, such an angle sensor still has the following problems: 1. although the magnet, the magnetic sensing element and the hall element are in non-contact, structurally, the measured rotating shaft fixed with the magnet still needs to extend into a sensor sensing cavity, so that the rotating shaft and a sensor shell are connected, the sensor is designed in an integrated mode, axial force and radial force generated when the rotating shaft rotates can affect the sensor, and if the sensor is used for a long time on large equipment (such as engineering machinery) capable of generating large axial force and radial force, the measurement accuracy of the sensor is reduced. 2. The sensor has poor tightness and firmness particularly at the joint of the rotating shaft, so that the waterproof and dustproof performance of the sensor is not high, and the protection grade of the sensor can reach IP43 at most. 3. The Hall type angular displacement sensor has poor linearity, low sensitivity and serious temperature drift due to the physical properties of the Hall type angular displacement sensor, and the accuracy of angular displacement measurement is influenced.

Disclosure of Invention

The invention aims to provide a non-contact angle displacement sensor based on giant magnetoresistance effect and a measuring method aiming at the defects of the prior art, so that the measuring accuracy and the service life of the angular displacement sensor are further improved.

In order to achieve the purpose, the invention adopts the technical scheme that:

a non-contact angle displacement sensor based on giant magnetoresistance effect comprises a sensing unit and an exciting unit; the sensing unit is of a cylindrical hollow structure, and a giant magnetoresistance chip is arranged in the middle of the bottom in the top of the sensing unit; the excitation unit is of a cylindrical hollow structure with an opening at one end, a magnetic strip is fixed at the middle position of the bottom in the sealing end of the excitation unit, and a rotating shaft connecting cavity is formed in the opening end of the excitation unit. During the use, the pivot that awaits measuring inserts the pivot connection chamber passes through the screwed connection and fixes the excitation unit, the sensing unit is installed on the fixed wall in the axial outside of the pivot that awaits measuring and is in same central axis with the excitation unit, and giant magnetoresistance chip is close to with the magnetic stripe relatively parallel.

Further, the sensing unit comprises a fixing flange, a length adjusting piece, a circuit accommodating piece and a circuit board; the bottom of the fixing flange is provided with three connecting and fixing holes, and the fixing flange, the length adjusting piece and the circuit accommodating piece are sequentially connected and fixed through the three connecting and fixing holes by long screws.

Further, the circuit board comprises a processing chip and the giant magnetoresistance chip; the giant magnetoresistance chip is connected with the processing chip and the circuit of the related device on the circuit board to form a sensing circuit; a circuit accommodating cavity is arranged in the middle of the bottom in the top end of the circuit accommodating piece; the circuit board is fixedly connected with the inner bottom of the top end of the circuit accommodating part through a screw, and the sensing circuit on the circuit board is arranged in the circuit accommodating cavity.

Furthermore, one end of the side wall of the length adjusting piece, which is close to the fixing flange, is provided with a wire outlet hole, and an external control cable is connected with a sensing circuit on the circuit board through the wire outlet hole.

Furthermore, all components and parts of the sensing unit and the exciting unit are encapsulated by adopting encapsulation glue, and preferably epoxy resin encapsulation glue is adopted.

Further, the magnetic strip is a rectangular, cylindrical or ring-shaped permanent magnet magnetized in the radial direction; the fixing flange, the length adjusting piece, the circuit accommodating piece and the excitation unit are all made of non-magnetic materials.

The giant magnetoresistance chip is a double-shaft giant magnetoresistance chip, and when the excitation unit is driven by the rotating shaft to be detected to rotate, V is generated in the X-axis direction and the Y-axis direction of the giant magnetoresistance chip respectively_xAnd V_yThe output voltage is calculated by a processing chip to obtain the value of angular displacement α which is 0-360 degrees, and the calculation is shown as the following formulas (A1), (A2) and (A3):

V_x＝V₀sin α (A1)

V_y＝V₀cos α (A2)

from (a1), (a 2):

wherein, V₀An initial voltage value is input.

Furthermore, a temperature sensor is arranged on the circuit board or outside the circuit board and is in circuit connection with the processing chip; and when the processing chip calculates the angular displacement value, the current temperature value captured by the temperature sensor is taken into the calibration curve to be calculated, the temperature drift of the angular displacement is corrected, and the corrected angular displacement value is output.

Further, the calibration curve adopts a zero drift curve or an output drift curve; the zero drift curve is obtained by placing an angular displacement sensor in an incubator, setting the angular displacement sensor to be in an initial 0-degree state, changing the temperature, recording output angular displacement values at different temperatures captured by the temperature sensor, obtaining a group of sequences corresponding to the temperature and the angular displacement, and fitting the sequences; the output drift curve is obtained by placing the angular displacement sensor in a temperature box, changing the temperature, rotating an excitation unit of the angular displacement sensor at different temperatures, recording output angular displacement values captured by the temperature sensor at different temperatures, obtaining a group of sequences corresponding to the temperature and the angular displacement, and fitting the sequences.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. due to the adoption of a split design, the sensor comprises a sensing unit and an exciting unit, and the axial force and the radial force generated by a rotating shaft in the exciting unit do not have any influence on the measuring end of the sensing unit, so that the measuring precision of the angular displacement sensor is improved;

2. because the giant magnetoresistance chip is used as an induction element, the angular displacement sensor has higher sensitivity, better linearity, lower use power consumption and smaller volume;

3. in the split type design, as the influence of the rotating shaft is avoided, all components of the sensor can be encapsulated by glue such as epoxy resin, so that the dustproof, waterproof and even anti-collision protection level of the angular displacement sensor is greatly improved, and the sealing property and the firmness of the angular displacement sensor are further enhanced;

4. when the angular displacement sensor is used, the sensing unit of the angular displacement sensor is always in a fixed state, and the length adjusting piece can be adapted to products with different sizes, so that the service life is further prolonged, and the application range is expanded;

5. the temperature drift correction technology is adopted in the circuit structure, so that the anti-interference capability and the measurement accuracy of the angular displacement sensor are improved.

Drawings

FIG. 1 is a schematic diagram of a non-contact angle displacement sensor based on giant magnetoresistance effect;

FIG. 2 is a left side view of a non-contact angle displacement sensor based on the giant magnetoresistance effect;

FIG. 3 is a cross-sectional view of a non-contact angle displacement sensor based on the giant magnetoresistance effect;

FIG. 4 is a front view of a non-contact angle displacement sensor based on the giant magnetoresistance effect;

FIG. 5 is a rear view of a non-contact angle displacement sensor based on the giant magnetoresistance effect;

FIG. 6 is a schematic diagram of the relative positions of a case-less GMR chip and a permanent magnet;

FIG. 7 is a schematic diagram of two-path signal output of a dual-axis GMR chip;

fig. 8 is a schematic view of an angular displacement signal processing structure.

The labels in the figure are: 1-a sensing unit, 2-an exciting unit, 3-a fixed flange, 4-a length adjusting piece, 5-a circuit accommodating piece, 6-a circuit board, 7-a giant magnetoresistance chip, 8-a processing chip, 9-a circuit accommodating cavity, 10-a wire outlet hole, 11-a base fixing hole, 12-a connecting fixing hole, 13-a permanent magnet, 14-a rotating shaft connecting cavity, 15-a magnet fixing cavity, 16-a rotating shaft fixing hole and 17-a circuit board connecting hole.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.