Eddy current sensor for automobile vibration measurement

Abstract

The invention relates to an eddy current sensor for automobile vibration monitoring in the field of sensors, and the eddy current sensor comprises a probe, a preposition device and an extension cable, the probe comprises a cylindrical hollow and closed shell, the lower end of the shell is in threaded connection with an end cover, and a first coil and a second coil are coaxially arranged in the shell; a magnetic core is inserted into the center of the first coil and the center of the second coil and fixed to the center of the shell. The first coil is fixed to the end cover, the second coil is located above the first coil, and weak springs are arranged on the upper side and the lower side of the second coil respectively. The front-end device integrates an oscillating circuit and a signal processing and temperature compensation module to realize signal linearization and anti-interference transmission; the extension cable adopts a double-layer shielding structure and a standardized interface to ensure the stability of long-distance signals. The device can timely and accurately measure the vibration of the automobile in the advancing process so as to provide an adjusting basis for air suspension.

Description

Technical Field

[0001] This invention relates to a vehicle sensor, and more particularly to a sensor for measuring vehicle vibration. Background Technology

[0002] In the existing technology, there is a type of car with air suspension. Air suspension can improve the comfort of the car, but air suspension itself is not intelligent enough. That is, although its shock absorption effect is good, it cannot directly change the internal gas pressure according to changes in road conditions. The fundamental reason is that the current air suspension does not measure vibration in time and has a hysteresis effect.

[0003] A vibration measurement device and method are disclosed in the Chinese Patent Database (Publication No.: CN114838803A, Publication Date: 20220802). The device includes a laser measurement component, a Doppler measurement component, a signal transceiver component, and an analysis calculator electrically connected to the laser and Doppler measurement components. Lasers emitted by the laser and Doppler measurement components are combined by the signal transceiver component and then emitted to the target. The signal transceiver component receives the light signal reflected from the target, splits it, and then sends it to the laser and Doppler measurement components respectively. The laser measurement component measures the vibration displacement using a pulsed laser ranging method, and the Doppler measurement component measures the vibration velocity using a laser Doppler method. The time-series displacement and velocity values ​​are transmitted to the analysis calculator for fusion processing using a Kalman filter algorithm. Furthermore, this invention also provides a vibration measurement method capable of measuring low-frequency vibrations over long distances. This vibration measurement device and method reduce dependence on the performance of the measuring equipment while ensuring detection accuracy. However, this device is not suitable for use in automobiles, as the vehicle environment itself is a vibration environment; the vibration measurement of this invention needs to be performed in a static environment. Summary of the Invention

[0004] The purpose of this invention is to provide an eddy current sensor for measuring vehicle vibration, enabling timely and accurate measurement of vehicle vibration during driving, so as to provide a basis for adjusting the air suspension.

[0005] Therefore, the technical solution of the present invention is: an eddy current sensor for measuring automotive vibration, comprising a probe, a preamplifier, and an extension cable. The probe comprises a cylindrical, hollow, and sealed housing, with an end cap threaded to the lower end of the housing. A first coil and a second coil are coaxially arranged inside the housing, and a magnetic core is inserted into the center of the first coil and the second coil. The magnetic core is fixed to the center of the housing. The first coil is fixed to the end cap, and the second coil is located above the first coil. Weak springs are respectively provided on the upper and lower sides of the second coil. The preamplifier is electrically connected to the first coil and the second coil via the extension cable. The preamplifier integrates a signal excitation module, a signal processing module, and a temperature compensation module. The signal excitation module generates a high-frequency oscillation signal, and the signal processing module processes the current signals returned by the first coil and the second coil and outputs an electrical signal corresponding to the vibration parameters. The extension cable has a double-shielded structure and standardized interfaces at both ends for connecting the probe and the preamplifier. The probe is installed inside the vehicle body. During driving, the vibration of the vehicle body triggers the displacement of the second coil relative to the first coil, thereby generating eddy current changes in the second coil. The second coil and the first coil receive the eddy current signal through electromagnetic coupling, and non-contact vibration measurement is achieved through the changes in eddy currents.

[0006] In operation, the probe is installed inside the vehicle body. During driving, the second coil is in a floating state, held in the middle by two weak springs. Vehicle vibration triggers the second coil to displace relative to the first coil. The change in magnetic flux gives it a damping effect, preventing continuous oscillation due to previous vibrations. This damping effect allows it to quickly reach a steady state, enabling rapid measurement of vibration data without affecting subsequent measurements. Based on the measured vibration data, the transient air pressure of the air suspension can be actively adjusted to provide a better riding experience. Compared with existing technologies, the advantages of this invention are: 1. High measurement accuracy: resolution up to 0.1μm, frequency response 50kHz, which can meet the needs of low-frequency vibration monitoring of vehicle body; 2. Good anti-interference: It can suppress common-mode noise and shielded cables reduce electromagnetic interference.

[0007] 3. Timely measurement: The air suspension can adjust the air pressure in a timely manner according to different road conditions, providing a better riding experience.

[0008] Furthermore, the second coil is mounted on a coil support, and the weak spring includes an upper spring and a lower spring, with the lower spring positioned between the first coil and the coil support; a spring seat is provided inside the housing, and the upper spring is positioned between the coil support and the spring seat.

[0009] To ensure accurate measurements, the inner cavity of the housing is filled with a heat-conducting liquid, and a microwave heater and a temperature measuring head are installed inside the housing to maintain a constant operating temperature of the probe. Microwave heating raises the probe to 40-50°C and maintains this temperature, preventing measurement data drift caused by temperature changes and improving weather resistance.

[0010] Furthermore, the signal processing module of the preamplifier includes: An oscillation circuit is used to generate a high-frequency sinusoidal excitation signal of 1-10 MHz; The demodulation circuit is used to multiply the signal returned by the probe with the original excitation signal and extract the low-frequency component corresponding to the displacement change of the second coil. The low-pass filter and linearization compensation circuit are used to filter and linearize the demodulated signal, and output a DC voltage signal that is linearly related to the vibration displacement. Temperature sensors and compensation algorithms are used to compensate for temperature drift in the output signal based on the collected temperature information, ensuring measurement accuracy across the entire temperature range.

[0011] The preamplifier is integrated into a metal shielded housing.

[0012] The shielding layer of the extension cable adopts a single-point grounding method, and its characteristic impedance is 75 ohms; the cable interface is equipped with gold-plated contacts and rubber sealing rings to ensure reliable connection and IP67 protection capability.

[0013] At least two eddy current sensors are installed in the vehicle, with the axes of the two eddy current sensors set perpendicular to each other. One sensor is used to measure longitudinal vibration, and the other is used to measure lateral vibration. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0015] Figure 2 This is a schematic diagram of the internal structure of the probe section.

[0016] In the diagram, 1 is the end cap, 2 is the housing, 3 is the microwave heater, 4 is the preamplifier, 5 is the extension cable, 6 is the spring seat, 7 is the upper spring, 8 is the second coil, 9 is the first coil, 10 is the magnetic core, 11 is the lower spring, 12 is the coil bracket, and 13 is the temperature sensor. Detailed Implementation

[0017] like Figure 1 and 2 As shown, an eddy current sensor for measuring automotive vibration is presented. Its structure mainly includes a probe, a preamplifier, and an extension cable. The probe includes a cylindrical, hollow, and sealed housing 2. An end cap 1 is threaded to the lower end of the housing 2. A first coil 9 and a second coil 8 are coaxially arranged inside the housing 2. A magnetic core 10 is inserted into the center of both the first coil 9 and the second coil 8, and the magnetic core 10 is fixed to the center of the housing 2. The first coil 9 is fixed to the end cap 1, and the second coil 8 is located above the first coil 9. Weak springs are provided on the upper and lower sides of the second coil 8, respectively. Specifically, the second coil 8 is mounted on a coil support 12, and the weak springs include an upper spring 7 and a lower spring 11, with the lower spring 11 positioned between the first coil 9 and the coil support 12. A spring seat 6 is provided inside the housing 2, and the upper spring 7 is positioned between the coil support 12 and the spring seat 6.

[0018] When the second coil 8 vibrates, it can move along the axial direction of the magnetic core 10.

[0019] End cap 1 and housing 2 are made of aluminum, which provides good shielding.

[0020] The preamplifier 4 is electrically connected to the first coil 9 and the second coil 8 via the extension cable 5. The preamplifier 4 integrates a signal excitation module, a signal processing module and a temperature compensation module. The signal excitation module generates a high-frequency oscillation signal, and the signal processing module processes the current signals returned by the first coil 9 and the second coil 8 and outputs an electrical signal corresponding to the vibration parameters.

[0021] The extension cable 5 has a double-shielded structure and standardized interfaces at both ends for connecting the probe and the preamplifier 4.

[0022] The probe is installed inside the car body. During driving, the vibration of the car body triggers the displacement of the second coil 8 relative to the first coil 9, thereby generating eddy current changes in the second coil 8. The second coil 8 and the first coil 9 receive the eddy current signal through electromagnetic coupling, and non-contact vibration measurement is achieved through the change of eddy current.

[0023] To ensure accurate measurements, the inner cavity of housing 2 is filled with a thermally conductive liquid. Housing 2 contains a microwave heater 3 and a temperature measuring head 13 to maintain a constant operating temperature for the probe. Microwave heating raises the probe to 40-50°C and maintains this temperature, preventing measurement data drift caused by temperature changes and improving weather resistance. The probe is encapsulated in high-temperature resistant PPS.

[0024] Furthermore, the signal processing module of the preamplifier 4 includes: An oscillation circuit is used to generate a high-frequency sinusoidal excitation signal of 1-10 MHz; The demodulation circuit is used to multiply the signal returned by the probe with the original excitation signal and extract the low-frequency component corresponding to the displacement change of the second coil 8. The low-pass filter and linearization compensation circuit are used to filter and linearize the demodulated signal, and output a DC voltage signal that is linearly related to the vibration displacement. Temperature sensors and compensation algorithms are used to compensate for temperature drift in the output signal based on the collected temperature information, ensuring measurement accuracy across the entire temperature range.

[0025] The preamplifier 4 is integrated into a metal shielded housing.

[0026] The shielding layer of extension cable 5 adopts a single-point grounding method, and its characteristic impedance is 75 ohms; the cable interface is equipped with gold-plated contacts and rubber sealing rings to ensure reliable connection and IP67 protection capability.

[0027] At least two eddy current sensors are installed in the car, with the axes of the two eddy current sensors set perpendicular to each other. One is used to measure longitudinal vibration, and the other is used to measure lateral vibration.

[0028] In operation, the probe is installed inside the vehicle body. During driving, the second coil 8 is in a floating state, held in the middle by two weak springs. Vehicle vibration triggers the second coil 8 to shift relative to the first coil 9. The change in magnetic flux gives it a damping effect, thus preventing continuous oscillation due to previous vibrations. The damping effect allows it to quickly enter a steady state, and its initial current peak reflects the amplitude of the vibration. Vibration data can be quickly measured without affecting subsequent measurements. Based on the measured vibration data, the transient air pressure of the air suspension can be actively adjusted to provide a better riding experience. Compared with existing technologies, the advantages of this invention are: 1. High measurement accuracy: resolution up to 0.1μm, frequency response 50kHz, which can meet the needs of low-frequency vibration monitoring of vehicle body; 2. Good anti-interference: It can suppress common-mode noise, and the shielded cable reduces electromagnetic interference; 3. Timely measurement: The air suspension can adjust the air pressure in a timely manner according to different road conditions, providing a better riding experience.

[0029] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. An eddy current sensor for measuring automotive vibration, characterized in that, The device includes a probe, a preamplifier, and an extension cable. The probe includes a cylindrical, hollow, and sealed housing with an end cap threaded to the lower end. A first coil and a second coil are coaxially arranged inside the housing, and a magnetic core is inserted into the center of the first and second coils. The magnetic core is fixed to the center of the housing. The first coil is fixed to the end cap, and the second coil is located above the first coil. Weak springs are provided on the upper and lower sides of the second coil, respectively. The preamplifier is electrically connected to the first coil and the second coil via the extension cable. The preamplifier integrates a signal excitation module, a signal processing module, and a temperature compensation module. The signal excitation module generates a high-frequency oscillation signal, and the signal processing module processes the current signals returned by the first coil and the second coil and outputs an electrical signal corresponding to the vibration parameters. The extension cable has a double-shielded structure and standardized interfaces at both ends for connecting the probe and the preamplifier. The probe is installed inside the vehicle body. During driving, the vibration of the vehicle body triggers the displacement of the second coil relative to the first coil, thereby generating eddy current changes in the second coil. The second coil and the first coil receive the eddy current signal through electromagnetic coupling, and non-contact vibration measurement is achieved through the changes in eddy currents.

2. The eddy current sensor for automotive vibration measurement according to claim 1, characterized in that, The second coil is mounted on a coil support, and the weak spring includes an upper spring and a lower spring, with the lower spring positioned between the first coil and the coil support; a spring seat is provided inside the housing, and the upper spring is positioned between the coil support and the spring seat.

3. An eddy current sensor for automotive vibration measurement according to claim 2, characterized in that, The inner cavity of the housing is filled with a heat-conducting liquid, and a microwave heater and a temperature measuring head are installed inside the housing to maintain the operating temperature of the probe at a constant level.

4. An eddy current sensor for automotive vibration measurement according to claim 3, characterized in that, The signal processing module of the preamplifier includes: An oscillation circuit is used to generate a high-frequency sinusoidal excitation signal of 1-10 MHz; The demodulation circuit is used to multiply the signal returned by the probe with the original excitation signal and extract the low-frequency component corresponding to the displacement change of the second coil. The low-pass filter and linearization compensation circuit are used to filter and linearize the demodulated signal, and output a DC voltage signal that is linearly related to the vibration displacement. Temperature sensors and compensation algorithms are used to compensate for temperature drift in the output signal based on the collected temperature information, ensuring measurement accuracy across the entire temperature range.

5. An eddy current sensor for automotive vibration measurement according to claim 4, characterized in that, The preamplifier is integrated into a metal shielded housing.

6. An eddy current sensor for automotive vibration measurement according to claim 1, characterized in that, The shielding layer of the extension cable adopts a single-point grounding method, and its characteristic impedance is 75 ohms; the cable interface is equipped with gold-plated contacts and rubber sealing rings to ensure reliable connection and IP67 protection capability.

7. An eddy current sensor for automotive vibration measurement according to claim 1, characterized in that, At least two eddy current sensors are installed in the vehicle, with the axes of the two eddy current sensors set perpendicular to each other. One sensor is used to measure longitudinal vibration, and the other is used to measure lateral vibration.

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