Non-contact eddy current sensor

Abstract

The utility model discloses a non-contact eddy current sensor, which relates to the technical field of eddy current sensors, and comprises a main control circuit for outputting square wave signals; the waveform conversion circuit converts the received square wave signal into a sine wave signal and outputs the sine wave signal; the high-frequency excitation circuit is used for generating a high-frequency magnetic field according to the received sine wave signal, and generating an induced voltage under the combined action of a metal object when the metal object is close to the non-contact eddy current sensor; and the front-end acquisition circuit acquires the induced voltage and outputs a corresponding voltage signal to the main control circuit, so that the main control circuit outputs corresponding measurement information according to the voltage signal. Therefore, the eddy current sensor can carry out non-contact measurement, the reliability is higher, and the measurement range is wider.

Description

Technical Field

[0001] This utility model relates to the field of eddy current sensor technology, and in particular to a non-contact eddy current sensor. Background Technology

[0002] Currently, eddy current sensors are generally made in a separate configuration, with the probe being a high-frequency coil connected to the back-end circuitry via a shielded cable. These sensors are susceptible to interference from surrounding magnetic fields and electromagnetic waves, and the elongation of the coaxial cable cannot be too large; otherwise, excessive transmission attenuation will affect the accuracy and uncertainty of the test. Therefore, providing a non-contact, reliable, and wide-range integrated eddy current sensor is a pressing issue that researchers in the field urgently need to address. Utility Model Content

[0003] The main purpose of this invention is to propose a non-contact eddy current sensor, which aims to solve the problems of eddy current sensors requiring contact measurement, large size, poor reliability, and narrow measurement range.

[0004] To achieve the above objectives, this utility model proposes a non-contact eddy current sensor, which includes:

[0005] The main control circuit is used to output square wave signals;

[0006] A waveform conversion circuit, wherein the signal input terminal of the waveform conversion circuit is electrically connected to the signal output terminal of the main control circuit, is used to convert the received square wave signal into a sine wave signal and then output it;

[0007] A high-frequency excitation circuit is provided, wherein the signal input terminal of the high-frequency excitation circuit is electrically connected to the signal output terminal of the waveform conversion circuit. The high-frequency excitation circuit is used to generate a high-frequency magnetic field based on the received sine wave signal, and to generate an induced voltage by interacting with the metal object when a metal object approaches the non-contact eddy current sensor.

[0008] The front-end acquisition circuit has its signal input terminal electrically connected to the signal output terminal of the high-frequency excitation circuit, and its signal output terminal electrically connected to the signal input terminal of the main control circuit. The front-end acquisition circuit is used to acquire the induced voltage and output the corresponding voltage signal to the main control circuit, so that the main control circuit outputs the corresponding measurement information according to the voltage signal.

[0009] In one embodiment, the high-frequency excitation circuit includes:

[0010] A waveform amplification unit, wherein the signal input terminal of the waveform amplification unit and the signal output terminal of the waveform conversion circuit are used to amplify the sine wave signal sent by the waveform conversion circuit;

[0011] The coil excitation unit has its input terminal electrically connected to the signal input terminal of the waveform amplification unit, and its output terminal electrically connected to the signal input terminal of the front-end acquisition circuit. It is used to receive the amplified sine wave signal and generate a high-frequency magnetic field. The coil excitation unit generates an induced voltage when a metal object approaches the non-contact eddy current sensor.

[0012] In one embodiment, the waveform amplification unit includes a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, and a transistor;

[0013] The first terminal of the first capacitor is electrically connected to the signal output terminal of the waveform conversion circuit. The second terminal of the first capacitor is electrically connected to the base of the transistor, the first terminal of the first resistor, and the first terminal of the second resistor. The second terminal of the first resistor is electrically connected to the signal input terminal of the coil excitation unit. The collector of the transistor is electrically connected to the signal output terminal of the coil excitation unit and the signal input terminal of the front-end acquisition circuit. The emitter of the transistor is electrically connected to the first terminal of the third resistor and the first terminal of the second capacitor. The second terminal of the second resistor, the second terminal of the third resistor, and the second terminal of the second capacitor are grounded.

[0014] In one embodiment, the coil excitation unit includes a first operating power supply connection terminal and a first coil;

[0015] The power supply connection terminal is electrically connected to the first end of the first coil and the signal input terminal of the waveform amplification unit, and the second end of the first coil is electrically connected to the signal output terminal of the waveform amplification unit and the signal input terminal of the front-end acquisition circuit.

[0016] In one embodiment, the front-end acquisition circuit includes:

[0017] The detector unit is electrically connected to the signal output terminal of the high-frequency excitation circuit, and is used to collect the induced voltage to output a corresponding voltage signal.

[0018] A voltage amplification unit is provided, wherein the signal input terminal of the voltage amplification unit is electrically connected to the signal output terminal of the detection unit, and the signal output terminal of the voltage amplification unit is electrically connected to the main control circuit. The voltage amplification unit amplifies the received voltage signal and outputs it to the main control circuit so that the main control circuit can output corresponding measurement information based on the voltage signal.

[0019] In one embodiment, the detection unit includes a detection diode and a third capacitor;

[0020] The anode of the detector diode is electrically connected to the signal output terminal of the high-frequency excitation circuit, the cathode of the detector diode is electrically connected to the signal input terminal of the voltage amplification unit and the first terminal of the third capacitor, and the second terminal of the third capacitor is grounded.

[0021] In one embodiment, the voltage amplification unit includes a resistor balance bridge, a voltage amplifier, a fourth resistor, a fourth capacitor, and a second operating power supply connection terminal.

[0022] The first end of the resistor balance bridge is electrically connected to the signal output terminal of the detector unit; the second end of the resistor balance bridge is electrically connected to the first end of the voltage amplifier; the third end of the resistor balance bridge is electrically connected to the second end of the voltage amplifier; the fourth end of the resistor balance bridge is grounded; the third end of the voltage amplifier is electrically connected to the second working power supply connection terminal; the fourth end of the voltage amplifier is electrically connected to the first end of the fourth capacitor; the second end of the fourth capacitor is electrically connected to the fifth end of the voltage amplifier and the first end of the fourth resistor; the second end of the fourth resistor is electrically connected to the sixth end of the voltage amplifier; and the seventh end of the voltage amplifier is electrically connected to the signal input terminal of the main control circuit.

[0023] In one embodiment, the non-contact eddy current sensor further includes:

[0024] An interface protection circuit is provided, wherein the signal input terminal of the interface protection circuit is electrically connected to the signal output terminal of the main control circuit, and the signal output terminal of the interface protection circuit is communicatively connected to an external device, and is used to suppress interference from external transient high voltage when communicating with the external device through a serial port.

[0025] In one embodiment, the non-contact eddy current sensor further includes:

[0026] A voltage regulator circuit, wherein the power input terminal of the voltage regulator circuit is electrically connected to an external power source, and is used to regulate the external power source and output a corresponding voltage for use by the non-contact eddy current sensor.

[0027] A polarity reversal protection circuit is provided on the line between the external power supply and the voltage regulator circuit. The circuit is used to disconnect the line between the external power supply and the voltage regulator circuit when the external power supply is reversed or when the voltage of the external power supply exceeds a preset threshold.

[0028] The technical solution of this utility model employs a non-contact eddy current sensor, characterized in that the non-contact eddy current sensor includes: a main control circuit for outputting a square wave signal; a waveform conversion circuit, the signal input terminal of which is electrically connected to the signal output terminal of the main control circuit, for converting the received square wave signal into a sine wave signal for output; a high-frequency excitation circuit, the signal input terminal of which is electrically connected to the signal output terminal of the waveform conversion circuit, the high-frequency excitation circuit for generating a high-frequency magnetic field based on the received sine wave signal, and for generating an induced voltage by interacting with a metal object approaching the non-contact eddy current sensor; and a front-end acquisition circuit, the signal input terminal of which is electrically connected to the signal output terminal of the high-frequency excitation circuit, and the signal output terminal of which is electrically connected to the signal input terminal of the main control circuit; the front-end acquisition circuit is used to acquire the induced voltage and output a corresponding voltage signal to the main control circuit, so that the main control circuit outputs corresponding measurement information based on the voltage signal. Thus, the non-contact eddy current sensor converts the square wave signal output by the main control circuit into a sine wave signal via a waveform conversion circuit and outputs it to the high-frequency excitation circuit to generate a high-frequency magnetic field. When a metal object approaches the non-contact eddy current sensor, it interacts with the metal object to generate an induced voltage. The front-end acquisition circuit acquires this induced voltage and outputs a corresponding voltage signal to the main control circuit. The main control circuit then outputs measurement information such as the displacement, vibration, and amplitude of the metal object based on the waveform and magnitude of the voltage signal. This enables the eddy current sensor to perform non-contact measurements with increased reliability and a wider measurement range. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1 A system block diagram of an embodiment of the non-contact eddy current sensor provided by this utility model;

[0031] Figure 2 A circuit structure diagram of one embodiment of the non-contact eddy current sensor provided by this utility model.

[0032] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0034] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0035] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0036] This utility model proposes a non-contact eddy current sensor. Please refer to [reference needed]. Figure 1 and Figure 2 Non-contact eddy current sensors include:

[0037] Main control circuit 1 is used to output square wave signals;

[0038] Waveform conversion circuit 2, the signal input terminal of waveform conversion circuit 2 is electrically connected to the signal output terminal of main control circuit 1, and is used to convert the received square wave signal into a sine wave signal for output;

[0039] The high-frequency excitation circuit 3 is electrically connected to the signal output terminal of the waveform conversion circuit 2. The high-frequency excitation circuit 3 is used to generate a high-frequency magnetic field based on the received sine wave signal, and to generate an induced voltage when a metal object approaches the non-contact eddy current sensor and interacts with the metal object.

[0040] The front-end acquisition circuit 4 is electrically connected to the signal output terminal of the high-frequency excitation circuit 3, and the signal output terminal of the front-end acquisition circuit 4 is electrically connected to the signal input terminal of the main control circuit 1. The front-end acquisition circuit 4 is used to acquire the induced voltage and output the corresponding voltage signal to the main control circuit 1 so that the main control circuit 1 can output the corresponding measurement information according to the voltage signal.

[0041] It is worth mentioning that the non-contact eddy current sensor in this solution uses an amplitude modulation measurement mode to measure metallic materials. Specifically, when the frequency remains constant but the amplitude changes, eddy currents are induced on the surface of the metal object opposite the sensor when the magnetic lines of force from the measuring coil radiate outwards from the sensor housing. The magnitude of this eddy current is related to the gap between the detection surface of the metal object and the coil. When the gap decreases, the induced voltage on the detection surface of the metal object increases, the inductance of the measuring coil decreases, and thus the amplitude of the oscillator decreases. This oscillator can be implemented by the main control circuit 1 connected to an oscillating crystal or an external oscillation circuit. This change can be converted into a corresponding electrical signal, i.e., a voltage signal, by the front-end acquisition circuit 4.

[0042] In this embodiment, the main control circuit 1 can be implemented using a microcontroller (MCU) or a digital signal processor (DSP). The waveform conversion circuit 2 can be implemented using an RC integrator circuit, an operational amplifier integrator circuit, or a digital integrator circuit. The signal source for the high-frequency excitation circuit 3 can be provided using technologies such as a crystal oscillator (e.g., an oscillating crystal connected to the main control circuit 1 or an external oscillator circuit), a frequency synthesizer, or a direct digital synthesizer (DDS). The signal amplification circuit of the high-frequency excitation circuit 3 can be implemented using an operational amplifier or a transistor amplifier. The matching network of the high-frequency excitation circuit 3 can be implemented using an LC network matching circuit. The front-end acquisition circuit 4 can be implemented using a detector diode D1 or a synchronous detector. Thus, the non-contact eddy current sensor can convert the PWM square wave signal output by the main control circuit 1 into a sine wave signal through the waveform conversion circuit 2, and then output it to the high-frequency excitation circuit 3 to amplify the sine wave signal and generate a sinusoidal alternating high-frequency magnetic field for the coil. This causes an induced voltage to be generated when a metal object approaches the non-contact eddy current sensor. The front-end acquisition circuit 4 collects the low-frequency induced voltage and outputs the corresponding voltage signal. The main control circuit 1 then calculates the change in the equivalent impedance of the coil and outputs the corresponding measurement information such as displacement, vibration, and amplitude.

[0043] In one embodiment, the high-frequency excitation circuit 3 includes:

[0044] The waveform amplification unit 31 has its signal input terminal connected to the signal output terminal of the waveform conversion circuit 2, and is used to amplify the sine wave signal sent by the waveform conversion circuit 2.

[0045] The coil excitation unit 32 has its input terminal electrically connected to the signal input terminal of the waveform amplification unit 31, and its output terminal electrically connected to the signal input terminal of the front-end acquisition circuit 4. It is used to receive the amplified sine wave signal and generate a high-frequency magnetic field. When a metal object approaches the non-contact eddy current sensor, the coil excitation unit 32 generates an induced voltage.

[0046] In this embodiment, the waveform amplification unit 31 can be implemented using a common-emitter amplifier circuit, a common-base amplifier circuit, or a common-collector amplifier circuit. The main function of the waveform amplification unit 31 is to amplify the sinusoidal signal sent by the waveform conversion circuit 2 to achieve sufficient intensity for subsequent processing and application. These circuit structures each have their own characteristics. The common-emitter amplifier circuit has good voltage amplification capability and moderate current amplification capability, suitable for applications requiring high voltage gain; the common-base amplifier circuit has better frequency response and stability, suitable for amplifying high-frequency signals; the common-collector amplifier circuit primarily amplifies current and has low output impedance, suitable for driving low-impedance loads. Depending on the actual application requirements, a suitable amplifier circuit structure can be selected to implement the function of the waveform amplification unit 31. The main function of the coil excitation unit 32 is to receive the amplified sinusoidal signal and convert it into a high-frequency magnetic field through a coil. When a metal object approaches the non-contact eddy current sensor, the high-frequency magnetic field generates eddy currents on the surface of the metal object, thereby generating an induced voltage. The magnitude and distribution of this induced voltage are related to factors such as the material, shape, and distance of the metal object. By detecting changes in the induced voltage, non-contact detection and measurement of the metal object can be achieved.

[0047] In summary, the high-frequency excitation circuit 3 in this embodiment effectively amplifies the sinusoidal signal and converts it into a high-frequency magnetic field through the coordinated operation of the waveform amplification unit 31 and the coil excitation unit 32. This provides powerful functional support for the non-contact eddy current sensor, enabling it to accurately and efficiently complete the detection and measurement tasks of metal objects.

[0048] Furthermore, the waveform amplification unit 31 includes a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a third resistor R3, and a transistor Q1;

[0049] The first terminal of the first capacitor C1 is electrically connected to the signal output terminal of the waveform conversion circuit 2. The second terminal of the first capacitor C1 is electrically connected to the base of the transistor Q1, the first terminal of the first resistor R1, and the first terminal of the second resistor R2. The second terminal of the first resistor R1 is electrically connected to the signal input terminal of the coil excitation unit 32. The collector of the transistor Q1 is electrically connected to the signal output terminal of the coil excitation unit 32 and the signal input terminal of the front-end acquisition circuit 4. The emitter of the transistor Q1 is electrically connected to the first terminal of the third resistor R3 and the first terminal of the second capacitor C2. The second terminals of the second resistor R2, the third resistor R3, and the second capacitor C2 are grounded. The waveform amplification unit 31 forms a common-emitter amplifier circuit with RC coupling through the first capacitor C1, the second capacitor C2, the first resistor R1, the second resistor R2, the third resistor R3, and the transistor Q1, thereby enabling the sinusoidal signal output by the waveform conversion circuit 2 to be coupled to the base of the transistor Q1 through the first capacitor C1, forming an alternating voltage signal. The alternating voltage signal controls the conduction level of transistor Q1, thereby changing the magnitude of the sinusoidal alternating voltage output from the collector. Since the waveform amplification unit 31 in this scheme uses a common-emitter amplifier circuit, it enables the non-contact eddy current sensor to have a wider frequency range.

[0050] The coil excitation unit 32 includes a first working power supply connection terminal and a first coil;

[0051] The power supply connection terminal is electrically connected to the first end of the first coil and the signal input terminal of the waveform amplification unit 31. The second end of the first coil is electrically connected to the signal output terminal of the waveform amplification unit 31 and the signal input terminal of the front-end acquisition circuit 4. After amplification by the transistor Q1, the first coil can generate a high-frequency sinusoidal alternating magnetic field through the amplified sinusoidal alternating voltage and the power supply connected to the first power supply connection terminal, so that the coil excitation unit 32 can generate an induced voltage when a metal object approaches the non-contact eddy current sensor.

[0052] In one embodiment, the front-end acquisition circuit 4 includes:

[0053] The detection unit 41 is electrically connected to the signal output terminal of the high-frequency excitation circuit 3, and is used to collect the induced voltage to output the corresponding voltage signal.

[0054] The voltage amplification unit 42 is electrically connected to the signal output terminal of the detection unit 41 and to the main control circuit 1. It is used to amplify the received voltage signal and output it to the main control circuit 1 so that the main control circuit 1 can output the corresponding measurement information according to the voltage signal.

[0055] In this embodiment, the detection unit 41 has the characteristic of unidirectional conductivity. Since the sinusoidal alternating magnetic field is a high-frequency carrier signal and the induced voltage is a low-frequency signal, the detection unit 41 has the function of low-pass filtering. It can collect the induced voltage from the high-frequency sinusoidal alternating magnetic field and output the corresponding voltage signal. After being amplified by the voltage amplification unit 42 (such as an operational amplifier circuit, a basic amplifier circuit and an integrated operational amplifier circuit), it is output to the main control circuit 1 so that the main control circuit 1 can output the specific information of the displacement, vibration and amplitude of the corresponding metal object according to the voltage signal.

[0056] Furthermore, the detection unit 41 includes a detection diode D1 and a third capacitor C3;

[0057] The anode of detector diode D1 is electrically connected to the signal output terminal of high-frequency excitation circuit 3, and the cathode of detector diode D1 is electrically connected to the signal input terminal of voltage amplification unit 42 and the first terminal of third capacitor C3. The second terminal of third capacitor C3 is grounded. Detector diode D1, through the third capacitor C3 added in detector unit 41, can short-circuit the high-frequency signal, retaining only the low-frequency signal portion, thereby achieving a low-pass filtering function. This allows it to output the corresponding voltage signal after acquiring the induced voltage.

[0058] The voltage amplification unit 42 includes a resistor balance bridge RB1, a voltage amplifier IC2, a fourth resistor R4, a fourth capacitor C4, and a second working power supply connection terminal;

[0059] The first terminal of the resistor balancing bridge RB1 is electrically connected to the signal output terminal of the detector unit 41. The second terminal of the resistor balancing bridge RB1 is electrically connected to the first terminal of the voltage amplifier IC2. The third terminal of the resistor balancing bridge RB1 is electrically connected to the second terminal of the voltage amplifier IC2. The fourth terminal of the resistor balancing bridge RB1 is grounded. The third terminal of the voltage amplifier IC2 is electrically connected to the second working power supply connection terminal. The fourth terminal of the voltage amplifier IC2 is electrically connected to the first terminal of the fourth capacitor C4. The second terminal of the fourth capacitor C4 is electrically connected to the fifth terminal of the voltage amplifier IC2 and the first terminal of the fourth resistor R4. The second terminal of the fourth resistor R4 is electrically connected to the sixth terminal of the voltage amplifier IC2. The seventh terminal of the voltage amplifier IC2 is electrically connected to the signal input terminal of the main control circuit 1. The resistance balance bridge RB1 consists of two adjustable resistors and two fixed resistors. Since the resistance balance bridge RB1 is an AC bridge, different measurement tasks (such as displacement, vibration, amplitude, etc.) require different bridge resistance configurations. When adjusting the bridge balance, at least two adjustable parameters are needed to adjust the bridge to achieve a balanced state. This allows the resistance balance bridge RB1 to not only complete different measurement tasks but also cover a wide measurement range. The voltage amplifier IC2 is set as a non-inverting amplifier. The fourth resistor R4 and the fourth capacitor C4 connected in the voltage amplifier IC2 form a gain feedback network with different coefficients, enabling the voltage amplifier IC2 to output voltage signals with a wide voltage range.

[0060] In one embodiment, the non-contact eddy current sensor further includes:

[0061] Interface protection circuit 5 has its signal input terminal electrically connected to the signal output terminal of main control circuit 1. The signal output terminal of interface protection circuit 5 is also connected to external devices for communication, and is used to suppress interference from external transient high voltages when communicating with external devices via serial port.

[0062] In this embodiment, the interface protection circuit 5 is also provided with one or more interfaces, such as RS485, RS232 or RS422, so that it can communicate with external devices through serial ports in ways such as RS485, RS422 or RS232. The interface protection circuit 5 can be implemented by connecting multiple TVS diodes to the interface, so as to suppress the interference of external transient high voltage.

[0063] In one embodiment, the non-contact eddy current sensor further includes:

[0064] The voltage regulator circuit 6 is electrically connected to an external power supply. It is used to regulate the external power supply and output a corresponding voltage for use by the non-contact eddy current sensor.

[0065] The polarity reversal protection circuit 7 is installed on the line between the external power supply and the voltage regulator circuit 6. It is used to disconnect the line between the external power supply and the voltage regulator circuit 6 when the external power supply is reversed or the voltage of the external power supply is detected to exceed a preset threshold.

[0066] In this embodiment, the voltage regulator circuit 6 can be implemented by a parallel voltage regulator circuit 6, a switching voltage regulator circuit 6, or a linear voltage regulator circuit 6. By connecting the power input terminal of the voltage regulator circuit 6 to an external power source, the external power source can be regulated and output with a corresponding voltage for use by the non-contact eddy current sensor. A diode D1 and a fuse are connected in series in the line between the external power source and the voltage regulator circuit 6 to disconnect the line between the external power source and the voltage regulator circuit 6 when the external power source is reverse-connected or when the voltage of the external power source exceeds a preset threshold.

[0067] The technical solution of this utility model employs a non-contact eddy current sensor, characterized in that the non-contact eddy current sensor includes: a main control circuit for outputting a square wave signal; a waveform conversion circuit, the signal input terminal of which is electrically connected to the signal output terminal of the main control circuit, for converting the received square wave signal into a sine wave signal for output; a high-frequency excitation circuit, the signal input terminal of which is electrically connected to the signal output terminal of the waveform conversion circuit, the high-frequency excitation circuit for generating a high-frequency magnetic field based on the received sine wave signal, and for generating an induced voltage by interacting with a metal object approaching the non-contact eddy current sensor; and a front-end acquisition circuit, the signal input terminal of which is electrically connected to the signal output terminal of the high-frequency excitation circuit, and the signal output terminal of which is electrically connected to the signal input terminal of the main control circuit; the front-end acquisition circuit is used to acquire the induced voltage and output a corresponding voltage signal to the main control circuit, so that the main control circuit outputs corresponding measurement information based on the voltage signal. Thus, the non-contact eddy current sensor converts the square wave signal output by the main control circuit into a sine wave signal via a waveform conversion circuit and outputs it to the high-frequency excitation circuit to generate a high-frequency magnetic field. When a metal object approaches the non-contact eddy current sensor, it interacts with the metal object to generate an induced voltage. The front-end acquisition circuit acquires this induced voltage and outputs a corresponding voltage signal to the main control circuit. The main control circuit then outputs measurement information such as the displacement, vibration, and amplitude of the metal object based on the waveform and magnitude of the voltage signal. This enables the eddy current sensor to perform non-contact measurements with increased reliability and a wider measurement range.

[0068] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A non-contact eddy current sensor, characterized in that, The non-contact eddy current sensor includes: The main control circuit is used to output square wave signals; A waveform conversion circuit, wherein the signal input terminal of the waveform conversion circuit is electrically connected to the signal output terminal of the main control circuit, is used to convert the received square wave signal into a sine wave signal and then output it; A high-frequency excitation circuit is provided, wherein the signal input terminal of the high-frequency excitation circuit is electrically connected to the signal output terminal of the waveform conversion circuit. The high-frequency excitation circuit is used to generate a high-frequency magnetic field based on the received sine wave signal, and to generate an induced voltage by interacting with the metal object when a metal object approaches the non-contact eddy current sensor. The front-end acquisition circuit has its signal input terminal electrically connected to the signal output terminal of the high-frequency excitation circuit, and its signal output terminal electrically connected to the signal input terminal of the main control circuit. The front-end acquisition circuit is used to acquire the induced voltage and output the corresponding voltage signal to the main control circuit, so that the main control circuit outputs the corresponding measurement information according to the voltage signal.

2. The non-contact eddy current sensor as described in claim 1, characterized in that, The high-frequency excitation circuit includes: A waveform amplification unit, wherein the signal input terminal of the waveform amplification unit and the signal output terminal of the waveform conversion circuit are used to amplify the sine wave signal sent by the waveform conversion circuit; The coil excitation unit has its input terminal electrically connected to the signal input terminal of the waveform amplification unit, and its output terminal electrically connected to the signal input terminal of the front-end acquisition circuit. It is used to receive the amplified sine wave signal and generate a high-frequency magnetic field. The coil excitation unit generates an induced voltage when a metal object approaches the non-contact eddy current sensor.

3. The non-contact eddy current sensor as described in claim 2, characterized in that, The waveform amplification unit includes a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, and a transistor; The first terminal of the first capacitor is electrically connected to the signal output terminal of the waveform conversion circuit. The second terminal of the first capacitor is electrically connected to the base of the transistor, the first terminal of the first resistor, and the first terminal of the second resistor. The second terminal of the first resistor is electrically connected to the signal input terminal of the coil excitation unit. The collector of the transistor is electrically connected to the signal output terminal of the coil excitation unit and the signal input terminal of the front-end acquisition circuit. The emitter of the transistor is electrically connected to the first terminal of the third resistor and the first terminal of the second capacitor. The second terminal of the second resistor, the second terminal of the third resistor, and the second terminal of the second capacitor are grounded.

4. The non-contact eddy current sensor as described in claim 2, characterized in that, The coil excitation unit includes a first working power supply connection terminal and a first coil; The power supply connection terminal is electrically connected to the first end of the first coil and the signal input terminal of the waveform amplification unit, and the second end of the first coil is electrically connected to the signal output terminal of the waveform amplification unit and the signal input terminal of the front-end acquisition circuit.

5. The non-contact eddy current sensor as described in claim 1, characterized in that, The front-end acquisition circuit includes: The detector unit is electrically connected to the signal output terminal of the high-frequency excitation circuit, and is used to collect the induced voltage to output a corresponding voltage signal. A voltage amplification unit is provided, wherein the signal input terminal of the voltage amplification unit is electrically connected to the signal output terminal of the detection unit, and the signal output terminal of the voltage amplification unit is electrically connected to the main control circuit. The voltage amplification unit amplifies the received voltage signal and outputs it to the main control circuit so that the main control circuit can output corresponding measurement information based on the voltage signal.

6. The non-contact eddy current sensor as described in claim 5, characterized in that, The detection unit includes a detection diode and a third capacitor; The anode of the detector diode is electrically connected to the signal output terminal of the high-frequency excitation circuit, the cathode of the detector diode is electrically connected to the signal input terminal of the voltage amplification unit and the first terminal of the third capacitor, and the second terminal of the third capacitor is grounded.

7. The non-contact eddy current sensor as described in claim 5, characterized in that, The voltage amplification unit includes a resistor balance bridge, a voltage amplifier, a fourth resistor, a fourth capacitor, and a second working power supply connection terminal. The first end of the resistor balance bridge is electrically connected to the signal output terminal of the detector unit; the second end of the resistor balance bridge is electrically connected to the first end of the voltage amplifier; the third end of the resistor balance bridge is electrically connected to the second end of the voltage amplifier; the fourth end of the resistor balance bridge is grounded; the third end of the voltage amplifier is electrically connected to the second working power supply connection terminal; the fourth end of the voltage amplifier is electrically connected to the first end of the fourth capacitor; the second end of the fourth capacitor is electrically connected to the fifth end of the voltage amplifier and the first end of the fourth resistor; the second end of the fourth resistor is electrically connected to the sixth end of the voltage amplifier; and the seventh end of the voltage amplifier is electrically connected to the signal input terminal of the main control circuit.

8. The non-contact eddy current sensor as described in claim 1, characterized in that, The non-contact eddy current sensor also includes: An interface protection circuit is provided, wherein the signal input terminal of the interface protection circuit is electrically connected to the signal output terminal of the main control circuit, and the signal output terminal of the interface protection circuit is communicatively connected to an external device, and is used to suppress interference from external transient high voltage when communicating with the external device through a serial port.

9. The non-contact eddy current sensor as described in claim 1, characterized in that, The non-contact eddy current sensor also includes: A voltage regulator circuit, wherein the power input terminal of the voltage regulator circuit is electrically connected to an external power source, and is used to regulate the external power source and output a corresponding voltage for use by the non-contact eddy current sensor. A polarity reversal protection circuit is provided on the line between the external power supply and the voltage regulator circuit. The circuit is used to disconnect the line between the external power supply and the voltage regulator circuit when the external power supply is reversed or when the voltage of the external power supply exceeds a preset threshold.

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