Eddy current rotating speed sensor

Abstract

The utility model provides an eddy current rotating speed sensor. The eddy current rotating speed sensor comprises a magnetic field generation module, an induction module, a signal processing module and a signal subdivision module, the magnetic field generation module is used for being controlled to generate a magnetic field and acting on a target gear; the sensing module is used for receiving a magnetic field signal reflected by a target gear and inputting the magnetic field signal to the signal processing module; the signal processing module is used for converting the magnetic field signal into a pulse signal and inputting the pulse signal into the signal subdivision module; the signal subdivision module comprises a digital phase discriminator, a digital oscillator and a frequency divider; the first input end of the digital phase discriminator is connected to the output end of the signal processing module, the output end of the digital phase discriminator is connected to the input end of the digital oscillator, and the output end of the digital oscillator is connected to the input end of the frequency divider. The output end of the frequency divider is connected to the second input end of the digital phase discriminator; through the sensor, a high-resolution rotating speed signal can be output.

Description

Technical Field

[0001] The utility model relates to the field of sensors, in particular to an eddy current speed sensor. Background Art

[0002] The operating principle of an eddy-current sensor is that when a coil carrying a high-frequency current is brought close to the metal being measured, the high-frequency electromagnetic field generated by the high-frequency current in the coil induces currents on the metal surface, known as eddy currents. The induced magnetic field generated by the induced current has an obstructive effect on the original magnetic field, causing the physical quantities of the coil to change. By detecting these changes in the relevant physical quantities, the speed measurement function is achieved. Eddy-current sensors are widely used in industrial fields, particularly in applications requiring non-contact measurement. For example, in high-speed rotating equipment such as steam turbines, generators, and compressors, eddy-current sensors can continuously monitor the status of the rotating shaft, providing critical information such as rotor imbalance, bearing wear, and other mechanical problems for early detection.

[0003] Although eddy current sensors are widely used in many fields, their resolution and sensitivity are still limited under high-speed rotation conditions. In particular, in situations where high-precision measurements are required, such as measuring the rotational speed of turbocharger blades, traditional eddy current sensors may not meet the requirements.

[0004] Therefore, in order to solve the above technical problems, it is urgent to propose a new technical means. Utility Model Content

[0005] In view of this, in order to improve the resolution under high-speed rotation conditions, the utility model proposes an eddy current rotation speed sensor.

[0006] The utility model provides an eddy current speed sensor, which includes a magnetic field generating module, a sensing module, a signal processing module and a signal segmentation module;

[0007] The magnetic field generating module is used to generate a magnetic field in a controlled manner and act on the target gear;

[0008] The sensing module is used to receive the magnetic field signal reflected by the target gear and convert it into an electrical signal to input into the signal processing module;

[0009] The signal processing module is used to convert the electrical signal into a pulse signal and input the pulse signal into the signal segmentation module;

[0010] The signal subdivision module includes a digital phase detector, a digital oscillator and a frequency divider; the first input end of the digital phase detector is connected to the output end of the signal processing module, the output end of the digital phase detector is connected to the input end of the digital oscillator, the output end of the digital oscillator is connected to the input end of the frequency divider, the output end of the frequency divider is connected to the second input end of the digital phase detector, and the digital oscillator outputs a high-resolution signal.

[0011] Furthermore, the induction module includes an induction coil, a coupling capacitor and an amplification module;

[0012] The same-name end of the induction coil is connected to the input end of the amplification module through a coupling capacitor, and the opposite-name end of the induction coil is connected to the negative input end of the amplification module; the output end of the amplification module is connected to the input end of the signal processing module.

[0013] Furthermore, the signal processing module includes an analog-to-digital conversion module and a pulse signal synthesis module;

[0014] The input end of the analog-to-digital conversion module is connected to the output end of the amplification module, and the output end of the analog-to-digital conversion module is connected to the input end of the pulse signal synthesis module; the analog-to-digital conversion module is used to output square wave pulse signal A and square wave pulse signal B;

[0015] The output end of the pulse signal synthesis module is connected to the input end of the signal subdivision module; the pulse signal synthesis module is used to synthesize the square wave pulse signal D;

[0016] Among them, the square wave pulse signal A represents the square wave pulse signal when the teeth of the target gear pass through the magnetic field, the square wave pulse signal B represents the square wave pulse signal when the groove of the target gear passes through the magnetic field, the high level of the square wave pulse signal D represents that the teeth of the target gear pass through the magnetic field, and the low level of the square wave pulse signal D represents that the groove of the target gear passes through the magnetic field.

[0017] Furthermore, it also includes a filtering module, the input end of the filtering module is connected to the output end of the amplifying module, and the output end of the filtering module is connected to the input end of the analog-to-digital conversion module.

[0018] Furthermore, the magnetic field generating module is an excitation coil.

[0019] Furthermore, the excitation coil has N layers and the N layers of excitation coils are connected in series in sequence;

[0020] Among them, N≥2.

[0021] Furthermore, the N layers of excitation coils are all spiral-shaped and adjacent excitation coils are wound in opposite directions.

[0022] Furthermore, the induction coil has M layers and the M layers of induction coils are sequentially connected in series;

[0023] Among them, M≥2.

[0024] Furthermore, the M layers of induction coils are all spiral-shaped and adjacent induction coils are wound in opposite directions.

[0025] The beneficial effects of the present invention are as follows: the present invention can realize non-contact measurement by setting an excitation coil, and is less affected by the environment; the present invention can realize fast and accurate phase detection through a digital phase detector; the digital oscillator can capture high-frequency signals and provide clearer measurement results; the frequency divider can reduce the high-frequency signal to a frequency range suitable for processing; by combining the high precision of the digital phase detector, the high resolution of the digital oscillator and the dynamic adjustment capability of the frequency divider, the resolution of signal processing can be significantly improved, ensuring efficient and accurate signal detection and processing in a high-speed environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0027] Figure 1 This is a schematic diagram of the overall circuit structure of the utility model.

[0028] Figure 2 This is a schematic diagram of the probe structure in an embodiment of the present utility model.

[0029] Figure 3 This is a measurement diagram of the present utility model.

[0030] Reference numerals: 1 - probe, 11 - excitation coil, 12 - induction coil. DETAILED DESCRIPTION

[0031] The following is a further description of the present invention with reference to the accompanying drawings:

[0032] The utility model provides an eddy current speed sensor, comprising a magnetic field generating module, a sensing module, a signal processing module and a signal segmentation module; Figure 1 As shown;

[0033] The magnetic field generating module is used to generate a magnetic field in a controlled manner and act on the target gear;

[0034] The sensing module is used to receive the magnetic field signal reflected by the target gear and input it into the signal processing module;

[0035] The signal processing module is used to convert the magnetic field signal into a pulse signal and input the pulse signal into the signal segmentation module;

[0036] The signal subdivision module includes a digital phase detector, a digital oscillator and a frequency divider; the first input end of the digital phase detector is connected to the output end of the signal processing module, the output end of the digital phase detector is connected to the input end of the digital oscillator, the output end of the digital oscillator is connected to the input end of the frequency divider, the output end of the frequency divider is connected to the second input end of the digital phase detector, and the digital oscillator outputs a high-resolution signal;

[0037] The digital phase detector, digital oscillator and frequency divider all adopt existing technologies and are not described in detail here. The above sensor can output a high-resolution speed signal.

[0038] In this embodiment, the magnetic field generating module is an excitation coil 11; the excitation coil 11 is provided on the probe 1, and the probe 1 can be a PCB board, such as Figure 2 As shown; the gear speed is measured by the probe as shown Figure 3 As shown, the magnetic field generating module can be connected to an oscillating circuit that outputs a high-frequency current to provide energy for the magnetic field generating module. The oscillating circuit can be a Clapp oscillator circuit, which is a prior art and will not be described in detail here. By using an excitation coil, a uniform or specifically shaped magnetic field can be generated, thereby improving the sensitivity and detection accuracy of the sensor.

[0039] In this embodiment, the excitation coil 11 has N layers and the N layers of excitation coils 11 are connected in series; that is, the end point of the i-th layer of coil is connected to the starting point of the i+1-th layer;

[0040] Wherein, N≥2, N is set according to the demand, and in order to reduce the volume, N is preferably 2; taking N=2 as an example, the structure of the excitation coil 11 is as follows Figure 2 As shown;

[0041] The starting point of the first layer of excitation coil 11 is the connection terminal J1, and the end point of the Nth layer of excitation coil 11 is the connection terminal J2. The connection terminals J1 and J2 are connected to the oscillation circuit, and the excitation coil 11 generates a magnetic field under the excitation of the oscillation circuit.

[0042] Connecting the excitation coils in series not only helps simplify the manufacturing process and save space, but also improves the flexibility and efficiency of the system. In certain applications, it can provide a stronger magnetic field and higher system efficiency.

[0043] In this embodiment, all N layers of excitation coils 11 are spiral-shaped, with adjacent excitation coils 11 wound in opposite directions. The spiral coil design helps generate a more concentrated and uniform magnetic field. When two adjacent coils are wound in opposite directions, mutual interference caused by crossing connecting wires can be avoided, thereby improving the quality and stability of the overall magnetic field.

[0044] In order to evenly distribute the electric field and reduce the breakdown risk caused by electric field concentration, an insulating layer can be set between the excitation coils. The method of setting the insulating layer is determined according to needs or experience. Preferably, an insulating layer is set every two layers of excitation coils.

[0045] In this embodiment, the induction module includes an induction coil 12, a coupling capacitor and an amplification module;

[0046] The same-name end of the induction coil 12 is connected to the input of the amplifier module via a coupling capacitor, and the opposite-name end of the induction coil 12 is connected to the negative input of the amplifier module. The output of the amplifier module is connected to the input of the signal processing module. The induction coil 12, coupling capacitor, and amplifier module form a resonant circuit that can select signals of a specific frequency and suppress interference from other frequencies. In the series resonant state, the impedances of the inductor and coupling capacitor cancel each other out, minimizing the total impedance of the circuit and enhancing the current flow capacity, thereby reducing energy loss. This helps improve the overall efficiency of the system. When the excitation coil and the induction coil are at the same resonant frequency, energy transfer efficiency is higher, reducing energy loss.

[0047] The amplification module adopts an existing amplification circuit, such as an amplification circuit composed of an operational amplifier. These existing structures are not described in detail here.

[0048] Using an induction coil to obtain the magnetic field changes generated by the excitation coil acting on the target device can improve sensitivity and detection accuracy.

[0049] In this embodiment, the induction coil 12 has M layers and the M layers of induction coils 12 are connected in series; that is, the end point of the j-th layer of coil is connected to the starting point of the j+1-th layer;

[0050] An insulating layer may also be provided between the induction coils. The specific setting method is determined based on experience or demand. Preferably, an insulating layer is provided every two layers of induction coils.

[0051] Wherein, M≥2, M is set according to requirements. To reduce the volume, M is preferably 2. The starting point of the first layer of induction coil 12 is the connection terminal G1, and the end point of the Mth layer of induction coil 12 is the connection terminal G2. The connection terminal G1 is connected to one end of the coupling capacitor, and the connection terminal G2 is connected to the second input end of the amplifier circuit.

[0052] Taking M=2 as an example, the M layers of induction coils 12 are arranged on the probe 1, and the induction coils 12 are preferably arranged parallel to the excitation coils 11 in the longitudinal direction, such as Figure 2 As shown, the vertical direction refers to Figure 2 The vertical direction shown;

[0053] An insulating layer is provided between the induction coil 12 and the excitation coil 11 to prevent electrical short circuit or current leakage, thereby improving the stability and safety of the sensor. In addition, in the absence of an insulating layer, electromagnetic coupling between the excitation coil and the induction coil may cause additional losses, which not only affects efficiency but may also interfere with measurement results. Therefore, providing an insulating layer between the induction coil and the excitation coil helps to improve detection accuracy.

[0054] Furthermore, the M layers of induction coils 12 are all spiral-shaped and the winding directions of adjacent induction coils 12 are opposite; the above arrangement can improve the quality and stability of the overall magnetic field.

[0055] In this embodiment, the signal processing module includes an analog-to-digital conversion module (i.e., an analog-to-digital converter) and a pulse signal synthesis module;

[0056] The input end of the analog-to-digital conversion module is connected to the output end of the amplification module, and the output end of the analog-to-digital conversion module is connected to the input end of the pulse signal synthesis module; the analog-to-digital conversion module is used to output square wave pulse signal A and square wave pulse signal B; the process of converting the analog signal into a square wave pulse signal is a prior art and can be achieved by an analog-to-digital converter equipped with a zero-crossing comparator. It is a prior art and will not be described in detail here.

[0057] The output end of the pulse signal synthesis module is connected to the input end of the signal subdivision module; the pulse signal synthesis module is used to synthesize a square wave pulse signal D; the pulse signal synthesis module measures the duration Ta of the square wave pulse signal A and the duration Tb of the square wave pulse signal B through the system clock, and outputs a high level according to the duration Ta and a low level according to the duration Tb, thereby synthesizing the square wave pulse signal D;

[0058] Among them, the square wave pulse signal A represents the square wave pulse signal when the teeth of the target gear pass through the magnetic field, the square wave pulse signal B represents the square wave pulse signal when the groove of the target gear passes through the magnetic field, the high level of the square wave pulse signal D represents that the teeth of the target gear pass through the magnetic field, and the low level of the square wave pulse signal D represents that the groove of the target gear passes through the magnetic field.

[0059] A square wave signal is a discrete digital signal that is easier to process and transmit than a continuously changing analog signal. Converting an analog signal into a square wave pulse signal can improve the signal's anti-interference ability, simplify circuit design, increase system reliability and stability, and adapt to complex industrial environments.

[0060] In this embodiment, a filtering module, ie, a filtering circuit, is further included. The input end of the filtering module is connected to the output end of the amplifying module, and the output end of the filtering module is connected to the input end of the analog-to-digital conversion module.

[0061] The filter circuit adopts an existing filter circuit. In this embodiment, a band-pass filter is formed by a second-order Butterworth high-pass filter and a second-order Butterworth low-pass filter.

[0062] If a signal is filtered before amplification, it may introduce weak interference, causing signal distortion, which is equivalent to adding noise. Therefore, when the signal amplitude is small and the noise amplitude is small, amplification before filtering can maximize the preservation of the original signal information and avoid signal distortion.

[0063] The principle of the above embodiment is explained as follows: when the gear teeth pass through the magnetic field, the frequency of the square wave signal A output by the analog-to-digital converter is f1; when the gear slot passes through the magnetic field, the frequency of the square wave signal B output by the analog-to-digital converter is f2; square wave A and square wave B form a continuously alternating square wave C;

[0064] When square wave A appears, the pulse signal synthesis module outputs a high level according to the duration of square wave A; when square wave B appears, the pulse signal synthesis module outputs a low level according to the duration of square wave B, forming a square wave signal D with a frequency of f3, that is, the pulse signal synthesis module outputs a square wave signal D with a frequency of f3;

[0065] The digital phase detector receives a square wave signal D with a frequency of f3 output by the pulse signal synthesis module, and inputs the square wave signal D into a digital oscillator. The digital oscillator outputs a subdivided square wave signal E with a frequency of f4. The square wave signal E with a frequency of f4 is input into a frequency divider for frequency division, and outputs a square wave signal F with a frequency of f5. The square wave signal F with a frequency of f5 is input into the digital phase detector. The digital phase detector compares the phases of the square wave signal D with a frequency of f3 and the square wave signal F with a frequency of f5, and outputs a lag or lead signal according to the comparison result. The square wave signal E with a frequency of f4 is adjusted based on the lag or lead signal, and the square wave signal F with a frequency of f5 is further adjusted so that the square wave signal F with a frequency of f5 approaches the square wave signal D with a frequency of f3. The above process is repeated, and finally the digital oscillator outputs a high-precision, high-resolution square wave signal representing the rotational speed.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and are not limiting. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. An eddy current speed sensor, characterized in that: It includes a magnetic field generating module, an induction module, a signal processing module and a signal segmentation module; The magnetic field generating module is used to generate a magnetic field in a controlled manner and act on the target gear; The sensing module is used to receive the magnetic field signal reflected by the target gear and convert it into an electrical signal to input into the signal processing module; The signal processing module is used to convert the electrical signal into a pulse signal and input the pulse signal into the signal segmentation module; The signal subdivision module includes a digital phase detector, a digital oscillator and a frequency divider; the first input end of the digital phase detector is connected to the output end of the signal processing module, the output end of the digital phase detector is connected to the input end of the digital oscillator, the output end of the digital oscillator is connected to the input end of the frequency divider, the output end of the frequency divider is connected to the second input end of the digital phase detector, and the digital oscillator outputs a high-resolution signal.

2. The eddy current speed sensor according to claim 1, characterized in that: The induction module includes an induction coil, a coupling capacitor and an amplification module; The same-name end of the induction coil is connected to the positive input end of the amplification module through a coupling capacitor, and the opposite-name end of the induction coil is connected to the negative input end of the amplification module; the output end of the amplification module is connected to the input end of the signal processing module.

3. The eddy current speed sensor according to claim 2, characterized in that: The signal processing module includes an analog-to-digital conversion module and a pulse signal synthesis module; The input end of the analog-to-digital conversion module is connected to the output end of the amplification module, and the output end of the analog-to-digital conversion module is connected to the input end of the pulse signal synthesis module; The analog-to-digital conversion module is used to output square wave pulse signal A and square wave pulse signal B; The output end of the pulse signal synthesis module is connected to the input end of the signal subdivision module; the pulse signal synthesis module is used to synthesize the square wave pulse signal D; Among them, the square wave pulse signal A represents the square wave pulse signal when the teeth of the target gear pass through the magnetic field, the square wave pulse signal B represents the square wave pulse signal when the groove of the target gear passes through the magnetic field, the high level of the square wave pulse signal D represents that the teeth of the target gear pass through the magnetic field, and the low level of the square wave pulse signal D represents that the groove of the target gear passes through the magnetic field.

4. The eddy current speed sensor according to claim 3, characterized in that: It also includes a filtering module, wherein the input end of the filtering module is connected to the output end of the amplifying module, and the output end of the filtering module is connected to the input end of the analog-to-digital conversion module.

5. The eddy current speed sensor according to claim 1, characterized in that: The magnetic field generating module is an excitation coil.

6. The eddy current speed sensor according to claim 5, characterized in that: The excitation coil has N layers and the N layers of excitation coils are connected in series in sequence; Among them, N≥2.

7. The eddy current speed sensor according to claim 6, characterized in that: The N layers of excitation coils are all spiral-shaped and the winding directions of adjacent excitation coils are opposite.

8. The eddy current speed sensor according to claim 2, characterized in that: The induction coil has M layers and the M layers of induction coils are connected in series in sequence; Among them, M≥2.

9. The eddy current speed sensor according to claim 8, characterized in that: The M layers of induction coils are all spiral-shaped and the winding directions of adjacent induction coils are opposite.

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