Two-way high-precision proximity switch based on Hall element

Abstract

The invention provides a two-way high-precision proximity switch based on a Hall element, and relates to the technical field of proximity switches, and the two-way high-precision proximity switch comprises a probe and a target. The target comprises a first shell and a permanent magnet; the probe comprises a second shell, a circuit board and a connector, the circuit board is installed in the second shell, the circuit board is connected with the connector through a wire, the connector is used for being connected with an external circuit, and a Hall element, a temperature curve module and other electrical elements are arranged on the circuit board; the probe and the target are installed on the fixed part and the movable part respectively, induction points of the probe and the target are aligned, and the inconsistency of the Hall element is eliminated by calibrating the relation between the output voltage and the magnetic field of the Hall element. The problems that a probe and a target of an existing Hall switch proximity switch must be used in a matched mode, maintainability is poor, and work is not stable at different temperatures are solved.

Description

Technical Field

[0001] The invention relates to the technical field of proximity switches, and in particular to a dual-path high-precision proximity switch based on Hall elements. Background Art

[0002] In various mechanical structures, proximity switches are required to determine whether the mechanical structure has moved into place.

[0003] The Hall switch type proximity switch structure includes a probe and a target. The probe has a Hall switch element and the target has a magnet. When the probe and the target are close, the Hall element works based on the Hall effect, which can sense the change in the magnetic field and the output change. The Hall effect is based on the interaction between moving charged particles and the external magnetic field. A current-carrying conductor will generate a potential difference in the direction perpendicular to the magnetic field in the magnetic field. The Hall potential difference is V = hiB sinα, where α is the angle between the magnetic field vector and the Hall plate, and h is the comprehensive sensitivity coefficient, whose value is related to the material, shape and temperature. The magnetic field can pass through non-magnetic materials, so the Hall sensor will not be disturbed by non-magnetic excess and can work in harsh environments. The general consistency of Hall sensors is not very good, and the sensitivity is related to temperature. The existing non-contact Hall proximity switches have poor consistency of Hall switch elements, so the probe and target must be used in combination. There is no interchangeability between different sets of probes. During maintenance, the probe and target must be disassembled and installed at the same time, which has poor maintainability.

[0004] Therefore, it is necessary to design a proximity switch based on the Hall effect to solve the problems that the probe and target of the existing Hall switch proximity switch must be used in combination, the maintainability is poor, and the operation is unstable at different temperatures. Summary of the invention

[0005] The object of the present invention is to provide a dual-channel high-precision proximity switch based on a Hall element, which can solve the problems of the existing Hall switch proximity switch that the probe and the target must be used in combination, the maintainability is poor, and the operation is unstable at different temperatures.

[0006] The present invention is achieved through the following technical solutions:

[0007] A dual-channel high-precision proximity switch based on a Hall element, comprising a probe and a target;

[0008] The target comprises a first shell and a permanent magnet, wherein the permanent magnet is embedded in the first shell;

[0009] The probe comprises a second housing, a circuit board and a connector, wherein the circuit board is installed in the second housing, the circuit board is connected to the connector via a wire, the connector is used to connect an external circuit, a Hall element, a temperature curve module and other electrical elements are arranged on the circuit board, and the temperature curve module is used to eliminate the influence of temperature through temperature compensation;

[0010] The probe and the target are respectively mounted on a fixed component and a movable component, and the sensing points of the probe and the target are aligned. The probe is powered and an output signal is derived through the connector. The Hall element is mounted at a position close to the target at the front end of the circuit board, and the inconsistency of the Hall element is eliminated by calibrating the relationship between the output voltage and the magnetic field of the Hall element.

[0011] Preferably, the permanent magnet is embedded in the first housing and fixed with a cover plate after being glued.

[0012] Preferably, the front end and the rear end of the circuit board are respectively limited by a clamping plate and a clamping sleeve, and are potted with glue.

[0013] Preferably, the probe is powered by an external power supply, and the voltage of the external power supply is reduced to the working voltage of the linear Hall element and stabilized by a built-in power module. The probe also has a built-in protection circuit.

[0014] Preferably, the other electrical components include a main control module, a temperature sensor, a comparator and an output circuit;

[0015] The signal output ends of the comparator, the temperature curve module and the temperature sensor are respectively connected to the main control module;

[0016] The voltage output end of the Hall element is connected to the first input end of the comparator, the reference voltage output end of the main control module is connected to the second output end of the comparator, and the output end of the comparator is also connected to the output circuit.

[0017] Preferably, the comparator adopts a Schmitt trigger, and the working method of the comparator includes:

[0018] Obtain the output voltage U of the Hall element input to the first input terminal of the comparator i and the reference voltage U at the second input F ;

[0019] Compare the output voltage U of the Hall element i and the reference voltage U F The size of U i >U F , then the comparator output U o Is the first level type; if U i F , then the output U of the comparator o is a second level type; if the first level type is a high level, the second level type is a low level, and if the first level type is a low level, the second level type is a high level. ​

[0020] Preferably, the method for calibrating the relationship between the output voltage and the magnetic field of the Hall element is:

[0021] Determine a target action position of the proximity switch, and obtain a magnetic field at the target action position;

[0022] Obtaining an output voltage of the Hall element in the magnetic field;

[0023] Determine the reference voltage U according to the output voltage F .

[0024] Preferably, the temperature compensation method is:

[0025] Obtain the output voltage U of the Hall element at different temperatures when the proximity switch is in the target action position iT , U iT is the output voltage of the Hall element at temperature T;

[0026] Based on the U iT Get the reference voltage U at temperature T FT .

[0027] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0028] The present invention calibrates the relationship between the output voltage and magnetic field of the Hall element, eliminates the inconsistency caused by the performance difference between different Hall elements, and solves the problem that the switch probe and target must be used in conjunction with each other and the maintainability is poor.

[0029] The present invention uses the temperature curve module to monitor and compensate the ambient temperature in real time, thereby eliminating the influence of temperature changes on the detection accuracy of the Hall element, solving the problem of unstable operation at different temperatures, and ensuring stable performance in a complex temperature environment.

[0030] The device combination of the present invention has strong adaptability to matching and temperature, is easy to combine with any probe and target, and can work stably in a wide operating temperature range, and can work stably and reliably in more scenarios and situations;

[0031] The dual-channel high-precision proximity switch of the present invention has no mechanical contacts, will not generate arcs, and has good reliability;

[0032] The invention has reasonable design, simple structure, low manufacturing cost, and easy realization of the calibration supplement method, and is convenient for promotion and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the structure of a dual-channel high-precision proximity switch based on a Hall element provided in Example 1 of the present invention;

[0034] Figure 2 A perspective schematic diagram of a dual-channel high-precision proximity switch based on a Hall element provided in Embodiment 1 of the present invention;

[0035] Figure 3 A schematic diagram of the installation of a proximity switch based on a Hall element provided in Example 1 of the present invention;

[0036] Figure 4 A circuit diagram of a dual-channel high-precision proximity switch based on a Hall element provided in Example 1 of the present invention;

[0037] Figure 5 A characteristic diagram of the working principle of the hysteresis circuit provided in Example 1 of the present invention;

[0038] Icons: 101 - second housing, 102 - first housing, 103 - connector, 104 - card board, 105 - card sleeve, 106 - circuit board, 107 - permanent magnet, 108 - probe, 109 - target. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Example 1

[0041] This embodiment provides a dual-channel high-precision proximity switch based on Hall elements. Figure 1-Figure 4 , including a probe 108 and a target 109;

[0042] The target 109 includes a first shell 102 and a permanent magnet 107, wherein the permanent magnet 107 is embedded in the first shell 102;

[0043] The probe 108 includes a second housing 101, a circuit board 106 and a connector 103. The circuit board 106 is installed in the second housing 101. The circuit board 106 is connected to the connector 103 through a wire. The connector 103 is used to connect an external circuit. A Hall element, a temperature curve module and other electrical components are arranged on the circuit board 106. The temperature curve module is used to eliminate the influence of temperature through temperature compensation. The Hall element can be limited by the card board 104.

[0044] The probe 108 and the target 109 are respectively mounted on a fixed component and a movable component, and the sensing points of the probe 108 and the target 109 are aligned. The probe 108 is powered and an output signal is derived through the connector 103. The Hall element is mounted at the front end of the circuit board 106 near the target 109, and the inconsistency of the Hall element is eliminated by calibrating the relationship between the output voltage and the magnetic field of the Hall element.

[0045] During operation of this embodiment, the magnetic induction intensity at the probe 108 changes with the changes of the probe 108 and the target 109, and then the Hall element outputs different analog electrical signals as the magnetic field changes. On this basis, the signal is input into the main control module, and a signal of approach or distance is output. The main control module of this embodiment can compensate for the inconsistency between different Hall elements and make the action points of different sensors consistent after calibration. The main control module of this embodiment is connected to a temperature sensor and a temperature curve, which can offset the temperature drift of the element and can work stably within a wider operating temperature range. On this basis, the probe 108 and the target 109 of this embodiment are interchangeable and do not need to be paired one by one, so they have good maintainability and can be used within a wider temperature range based on temperature compensation.

[0046] In this embodiment, the permanent magnet 107 is embedded in the first housing 102 and is glued with glue and then fixed with a cover plate.

[0047] As a preferred solution of this embodiment, the front end and the rear end of the circuit board 106 are respectively limited by a clamping plate 104 and a clamping sleeve 105, and are potted with glue.

[0048] It is particularly noted that the connector 103 of this embodiment is sealed with a rubber gasket between the second housing 101, and the first housing 102 and the second housing 101 are both made of non-ferromagnetic aluminum alloy or titanium alloy to avoid interference with the magnetic field. The wires here are preferably not potted but fixed with silicone rubber that is easy to tear off, which can facilitate inspection and maintenance. At the same time, during installation, the first housing 102 and the second housing 101 can be fixed to the mounting base by bolts. The target 109 contains a permanent magnet 107, which is installed in the groove of the target 109, glued with glue and pressed with a cover plate to prevent it from moving.

[0049] Furthermore, the probe 108 is powered by an external power supply, and the voltage of the external power supply is reduced to the working voltage of the linear Hall element and stabilized by a built-in power module. The probe 108 also has a built-in protection circuit to provide protection against overvoltage and reverse connection. In the specific design, the output can be isolated by a solid-state relay to prevent mutual influence when the front and rear stages fail. The internal circuit of the probe 108 is preferably designed as a dual-path.

[0050] In addition, the other electrical components include a main control module, a temperature sensor, a comparator and an output circuit;

[0051] The signal output ends of the comparator, the temperature curve module and the temperature sensor are respectively connected to the main control module;

[0052] The voltage output end of the Hall element is connected to the first input end of the comparator, the reference voltage output end of the main control module is connected to the second output end of the comparator, and the output end of the comparator is also connected to the output circuit.

[0053] In terms of circuit design, the comparator adopts a Schmitt trigger, and the working method of the comparator includes:

[0054] Obtain the output voltage U of the Hall element input to the first input terminal of the comparator i and the reference voltage U at the second input F ;

[0055] Compare the output voltage U of the Hall element i and the reference voltage U F The size of U i >U F , then the comparator output U o Is the first level type; if U i F , then the output U of the comparator o is a second level type; if the first level type is a high level, the second level type is a low level, and if the first level type is a low level, the second level type is a high level.

[0056] Furthermore, the method for calibrating the relationship between the output voltage and magnetic field of the Hall element is:

[0057] Determine a target action position of the proximity switch, and obtain a magnetic field at the target action position;

[0058] Obtaining an output voltage of the Hall element in the magnetic field;

[0059] Determine the reference voltage U according to the output voltage F .

[0060] Finally, the temperature compensation method is:

[0061] Obtain the output voltage U of the Hall element at different temperatures when the proximity switch is in the target action position iT , U iT is the output voltage of the Hall element at temperature T;

[0062] Based on the U​iT Get the reference voltage U at temperature T FT .

[0063] Since the present embodiment selects the Schmitt trigger, based on the working principle of the hysteresis circuit of the Schmitt trigger itself, its characteristic diagram can be referred to in Figure 5 . Take U i F For example, when the Hall element outputs a high level, the reference voltage U F Features are as follows:

[0064] The two boundary values ​​of the hysteresis region of the Schmitt trigger are U L and U H , which is the voltage at the action point;

[0065] When the Hall element voltage U i When the reference voltage U F =U H , at this time U o is high level;

[0066] When the output voltage U i Increase and reach U H When the reference voltage U F =U L , at this time U o is low level;

[0067] When the output voltage U i Lower and reach U L When U o is high level, then the reference voltage U F =U H , U i Continue to reduce U o Still at high level.

[0068] If temperature compensation is not performed, the operating point of the proximity switch will change after the temperature changes. Therefore, this embodiment calibrates the temperature response of the Hall element and records the output voltage of the Hall element at different temperatures at the operating point. The main control module in the present invention can record and store the corresponding voltage U at different temperatures T. L and U H , that is, U LT and U HT When the temperature sensor measures the temperature change to this temperature, the reference voltage changes with the temperature, and the action voltage of the action point is changed by U L and U H Change to U LT and U HT ​, which matches the output voltage of the Hall element at that temperature, eliminating the influence of temperature and keeping the operating point of the product stable at different temperatures.

[0069] That is to say, with the cooperation of the Schmitt trigger, the reference voltage U F The actual working process follows the U of Schmitt trigger L and U H When temperature compensation is performed and the relationship between the output voltage and magnetic field of the Hall element is calibrated, the reference voltage U at temperature T is measured. FT , that is, the action voltage of the Hall element at temperature T can reflect the U of the Schmitt trigger at this time L and U H At this time, the reference voltage U FT According to the above working principle, based on U L and U H Work.

[0070] On the other hand, when the relationship between the output voltage and magnetic field of the Hall element is calibrated, the output voltage of the Hall element in the magnetic field can be used to obtain the action voltage of the Hall element at this time, which can reflect the U of the Schmitt trigger at this time. L and U H , and then it can be used as the reference voltage U at this time F of setting the benchmark.

[0071] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dual-channel high-precision proximity switch based on Hall elements, characterized in that: Including probe and target; The target comprises a first shell and a permanent magnet, wherein the permanent magnet is embedded in the first shell; The probe comprises a second housing, a circuit board and a connector, wherein the circuit board is installed in the second housing, the circuit board is connected to the connector via a wire, the connector is used to connect an external circuit, a Hall element, a temperature curve module and other electrical elements are arranged on the circuit board, and the temperature curve module is used to eliminate the influence of temperature through temperature compensation; The probe and the target are respectively mounted on a fixed component and a movable component, and the sensing points of the probe and the target are aligned. The probe is powered and an output signal is derived through the connector. The Hall element is mounted at a position close to the target at the front end of the circuit board, and the inconsistency of the Hall element is eliminated by calibrating the relationship between the output voltage and the magnetic field of the Hall element.

2. A dual-channel high-precision proximity switch based on Hall elements according to claim 1, characterized in that: The permanent magnet is embedded in the first housing and fixed with a cover plate after being glued.

3. A dual-channel high-precision proximity switch based on Hall elements according to claim 1, characterized in that: The front end and the rear end of the circuit board are respectively limited by a clamping plate and a clamping sleeve, and are potted with glue.

4. A dual-channel high-precision proximity switch based on Hall elements according to claim 1, characterized in that: The probe is powered by an external power supply, and the voltage of the external power supply is reduced to the working voltage of the linear Hall element and voltage stabilization is achieved through a built-in power module. The probe also has a built-in protection circuit.

5. A dual-channel high-precision proximity switch based on Hall elements according to claim 1, characterized in that: The other electrical components include a main control module, a temperature sensor, a comparator and an output circuit; The signal output ends of the comparator, the temperature curve module and the temperature sensor are respectively connected to the main control module; The voltage output end of the Hall element is connected to the first input end of the comparator, the reference voltage output end of the main control module is connected to the second output end of the comparator, and the output end of the comparator is also connected to the output circuit.

6. A dual-channel high-precision proximity switch based on Hall elements according to claim 5, characterized in that: The comparator adopts a Schmitt trigger, and the working method of the comparator includes: Obtain the output voltage U of the Hall element input to the first input terminal of the comparator i and the reference voltage U at the second input F ; Compare the output voltage U of the Hall element i and the reference voltage U F The size of U i >U F , then the comparator output U o Is the first level type; if U i F , then the output U of the comparator o is a second level type; if the first level type is a high level, the second level type is a low level, and if the first level type is a low level, the second level type is a high level.​ 7. A dual-channel high-precision proximity switch based on Hall elements according to claim 6, characterized in that: The method for calibrating the relationship between the output voltage and magnetic field of the Hall element is: Determine a target action position of the proximity switch, and obtain a magnetic field at the target action position; Acquiring an output voltage of the Hall element in the magnetic field; Determine the reference voltage U according to the output voltage F .

8. A dual-channel high-precision proximity switch based on Hall elements according to claim 7, characterized in that: The temperature compensation method is: Obtain the output voltage U of the Hall element at different temperatures when the proximity switch is in the target action position iT , U iT is the output voltage of the Hall element at temperature T; Based on the U iT Get the reference voltage U at temperature T FT .

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