A non-contact magnetostrictive linear displacement sensor

Abstract

The utility model relates to a kind of non-contact magnetostrictive linear displacement sensors, including measuring rod assembly, waveguide silk being coaxially arranged in measuring rod assembly, electronic cabinet being fixed in one end of measuring rod assembly and position magnet being movably arranged in the outside of measuring rod assembly, the integral type excitation and detection module is equipped in the electronic cabinet, and the module includes pulse current generating circuit and piezoelectric ceramic transducer, the piezoelectric ceramic transducer is mechanically coupled with the end of waveguide silk by coupling block, for exciting torsional stress wave to waveguide silk and detecting torsional stress wave returned from position magnet. The utility model solves the problems of large signal attenuation, weak anti-interference ability, high temperature sensitivity and complex structure in the prior art, has high signal-to-noise ratio, simplified structure, good thermal stability and strong anti-interference ability, etc. Advantages, suitable for industrial automation, hydraulic cylinder position detection and other long-stroke high-precision measurement scenarios.

Description

Technical Field

[0001] This invention relates to the field of displacement measurement technology, and more particularly to a non-contact magnetostrictive linear displacement sensor, specifically a sensor with an improved structure capable of high-precision, non-contact absolute position measurement. This sensor is suitable for applications requiring long-stroke, high-reliability displacement measurement, such as industrial automation, hydraulic cylinder position detection, precision machine tools, robotics, aerospace, and automotive manufacturing. By optimizing the sensor structure and signal processing mechanism, this invention solves the problems of signal attenuation, temperature drift, structural complexity, and insufficient anti-interference capability of traditional magnetostrictive displacement sensors in long-stroke applications, achieving higher measurement accuracy and stability. Background Technology

[0002] Magnetostrictive linear displacement sensors are devices that utilize the magnetostrictive effect for non-contact position measurement. Due to their high precision, high reliability, absolute position output, and long lifespan, they are widely used in various industrial applications. The magnetostrictive effect refers to the physical phenomenon where ferromagnetic materials change length under the influence of a magnetic field; conversely, the magnetization state changes when the material deforms. In displacement sensors, the Villari effect is typically used. When a current pulse passes through a waveguide wire (magnetostrictive material), a stress wave is generated at the intersection with the magnetic field of the position magnet. Displacement is calculated by measuring the propagation time of this stress wave.

[0003] The basic structure of a traditional magnetostrictive displacement sensor includes: a waveguide wire (usually made of a magnetostrictive material such as an iron-cobalt alloy), an electron chamber (containing a pulse generator and signal processing circuitry), and a movable position magnet. During operation, the pulse generator in the electron chamber produces a current interrogation pulse, which propagates along the waveguide wire. When the current pulse intersects with the magnetic field of the position magnet, the waveguide wire generates an instantaneous torsional stress wave. This stress wave propagates at the speed of sound towards both ends of the waveguide wire, and the stress wave returning to the electron chamber is detected by a transducer (such as a coil). By measuring the time difference between the emission of the current pulse and the return of the stress wave, the absolute position of the position magnet can be calculated.

[0004] However, existing technologies have several inherent limitations that restrict their performance in long-stroke and high-precision applications: Signal attenuation and noise issues: When stress waves propagate in a waveguide wire, they are attenuated due to material damping, geometric scattering, and environmental influences. Especially when the stroke exceeds 3 meters, the signal amplitude decreases significantly, the signal-to-noise ratio (SNR) drops, and measurement errors increase. For example, in hydraulic cylinder position detection, environmental vibrations and electromagnetic interference introduce noise, making small signals difficult to detect. Existing sensors mostly employ analog amplification and filtering techniques, but their effectiveness is limited and they easily introduce additional noise.

[0005] Structural complexity and high cost: Traditional sensors use separate excitation and detection coils, which require precise winding and installation, resulting in complex processes and poor consistency. Furthermore, mechanical damping mechanisms are often added to suppress reflected waves, increasing the number of parts and assembly difficulty. This complex structure leads to high production costs, reduced reliability, and is unfavorable for mass production. For example, in precision machine tool applications, the miniaturization and lightweighting requirements of sensors are difficult to meet.

[0006] Temperature drift error: The propagation speed of stress waves in a waveguide wire changes with temperature, with a typical temperature coefficient of 0.01% per degree Celsius. In applications with a wide temperature range (-40°C to 85°C), displacement errors can reach several millimeters without compensation. Existing technologies typically use external temperature sensors or software compensation, but these methods are slow to respond, have low accuracy, and are not integrated into the sensor, resulting in insufficient real-time performance.

[0007] Echo interference problem: After the stress wave is reflected at the end of the waveguide wire, it will form a secondary echo, which will be superimposed on the main measurement signal, causing signal aliasing. Traditional dampers are simple in design, but have impedance mismatch, low absorption efficiency, and significant reflected wave interference, especially increasing the error in high-speed measurements.

[0008] To address the aforementioned issues, the industry has undertaken various improvement attempts. For example, some patents employ multi-coil designs to improve the signal-to-noise ratio, but this increases complexity; other solutions use digital signal processing (DSP) for temperature compensation, but do not solve the structural problems. Chinese patent CN216558729U discloses a magnetostrictive displacement sensor, comprising a mounting flange, a circuit board, a waveguide wire, a first damping device, a strip, a data acquisition coil, an outer protective tube, and a second damping device; the circuit board is fixed to the top of the outer protective tube; the second damping device and the first damping device are sequentially sleeved on the waveguide wire; the circuit board is sleeved on the second damping device; the strip is mounted on the waveguide wire and located below the first damping device; the data acquisition coil is sleeved on the strip and fixed inside the outer protective tube; the outer wall of the top of the outer protective tube has external threads, and the lower end of the inner wall of the mounting flange has internal threads; the bottom of the mounting flange is fixed to the top of the outer protective tube by threaded engagement and seals with the outer protective tube to form an electronic compartment for accommodating the circuit board, waveguide wire, second damping device, first damping device, strip, and data acquisition coil. While it reduces attenuation by optimizing coil layout, it still relies on traditional electromagnetic transduction methods, resulting in insufficient signal purity. Therefore, there is an urgent need in this field for a new type of sensor with high integration and stable performance.

[0009] Based on an in-depth analysis of the existing defects, this invention proposes an innovative integrated excitation and detection module that combines digital signal processing and temperature compensation, fundamentally solving the aforementioned problems. Utility Model Content

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a non-contact magnetostrictive linear displacement sensor, solving the following technical problems: Signal attenuation and noise interference during long-distance transmission lead to a decrease in measurement accuracy.

[0011] Sensors have complex structures, many parts, are difficult to assemble, and are costly.

[0012] Temperature changes cause sound speed drift, resulting in significant measurement errors.

[0013] Echo interference generated by the reflection at the end of the stress wave affects the reliability of signal detection.

[0014] Through integrated design and advanced signal processing, this invention achieves high signal-to-noise ratio, simplified structure, excellent thermal stability, and strong anti-interference capability, meeting the high requirements of industrial applications.

[0015] The above-mentioned utility model objective is achieved through the following technical solution: This invention provides a non-contact magnetostrictive linear displacement sensor, comprising a probe assembly, a waveguide wire coaxially disposed within the probe assembly, an electronic compartment fixed to one end of the probe assembly, and a position magnet movably disposed outside the probe assembly. The electronic compartment contains an integrated excitation and detection module, which includes a pulse current generating circuit and a piezoelectric ceramic transducer. The piezoelectric ceramic transducer is mechanically coupled to the end of the waveguide wire via a coupling block, and is used to excite torsional stress waves to the waveguide wire and detect the torsional stress waves returning from the position magnet.

[0016] According to one embodiment of the present invention, the electronic compartment is further provided with a DSP (digital signal processor), which is electrically connected to the pulse current generating circuit and the piezoelectric ceramic transducer, and is used to control the transmission of interrogation pulses and perform digital signal processing on the detected echo signals to calculate displacement values.

[0017] According to one embodiment of the present invention, the electronic compartment is further provided with a temperature sensor, which is connected to the DSP. The DSP has a built-in sound velocity-temperature compensation algorithm for real-time temperature compensation of the displacement calculation results based on the temperature sensor readings.

[0018] According to one embodiment of the present invention, a damper is provided at the end of the waveguide wire, and the acoustic impedance of the damper is matched with that of the waveguide wire to absorb stress wave energy and suppress end reflection.

[0019] According to one embodiment of the present invention, the coupling block is made of a non-magnetic material with high hardness and high elastic modulus, preferably zirconium oxide ceramic or tungsten carbide, with a hardness of not less than HRA90 and an elastic modulus of not less than 300 GPa.

[0020] According to one embodiment of the present invention, the piezoelectric ceramic transducer is a piezoelectric ceramic element operating in shear mode, with a piezoelectric constant d15 of not less than 300 pC / N and a resonant frequency range of 100 kHz to 500 kHz.

[0021] According to one embodiment of the present invention, the signal processing performed by the digital signal processor includes digital filtering, coherent integration, and time-to-digital conversion, wherein the digital filtering adopts an FIR filter with an adjustable cutoff frequency, and the number of coherent integrations is 64 to 256.

[0022] According to one embodiment of the present invention, the measuring rod assembly is a sealed metal tube made of stainless steel or aluminum alloy with a wall thickness of 0.5 mm to 2 mm. The waveguide wire is in a taut state inside the tube with a preload of 50 N to 200 N.

[0023] According to one embodiment of the present invention, the electronic compartment is fixed to one end of the measuring rod assembly by threaded connection or welding. The outer shell of the electronic compartment has an IP67 protection rating, and the internal circuit board is encapsulated with epoxy resin.

[0024] According to one embodiment of the present invention, the sensor further includes an output interface circuit that supports analog output and digital output. The analog output includes 4-20mA or 0-10V, and the digital output includes an SSI interface or an RS485 interface.

[0025] In summary, compared with the prior art, the present invention has at least one of the following beneficial technical effects: High signal-to-noise ratio and sensitivity: Direct excitation and detection by piezoelectric ceramics achieves an energy conversion efficiency of over 80%, resulting in pure stress wave signals with large amplitude. Combined with digital filtering and coherent integration by DSP, the signal-to-noise ratio is improved by over 20 dB, making it particularly suitable for long-stroke (e.g., 5 meters) measurements with an accuracy of ±0.01% FS.

[0026] Simplified structure and reduced costs: The integrated module replaces the traditional coil structure, reducing parts by 50% and assembly time by 30%. Modular design improves production consistency and reliability, and reduces costs by 20%.

[0027] Excellent thermal stability: Built-in temperature compensation algorithm corrects sound speed drift in real time, reducing temperature error from ±0.1% FS to ±0.01% FS, and operates stably in the range of -40°C to 85°C.

[0028] Strong anti-interference capability: Optimized damper absorption efficiency reaches 95%, significantly suppressing reflected waves. Digital filtering eliminates electromagnetic interference, suitable for harsh industrial environments.

[0029] Highly scalable: The output interface is flexible, supports multiple communication protocols, and is easy to integrate into intelligent systems.

[0030] This invention achieves high performance and miniaturization of displacement sensors through innovative integration, providing a reliable solution for industrial automation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0032] Reference numerals: 1. Measuring rod assembly; 2. Waveguide wire; 3. Electronic chamber; 4. Position magnet; 5. Output cable; 31. Pulse current generating circuit; 32. Piezoelectric ceramic transducer; 33. Coupler block; 34. DSP; 35. Temperature sensor; 37. Output interface circuit; 21. Damper. Detailed Implementation

[0033] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0034] In the description of this application, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] Example 1: Reference Figure 1 This utility model discloses a non-contact magnetostrictive linear displacement sensor, which includes a probe assembly 1, a waveguide wire 2 coaxially disposed within the probe assembly 1, an electronic chamber 3 fixed to one end of the probe assembly 1, and a position magnet 4 movably disposed outside the probe assembly 1. The electronic chamber 3 is equipped with an integrated excitation and detection module, which includes a pulse current generating circuit 31 and a piezoelectric ceramic transducer 32. The piezoelectric ceramic transducer 32 is mechanically coupled to the end of the waveguide wire 2 through a coupling block 33, and is used to excite torsional stress waves to the waveguide wire 2 and detect the torsional stress waves returning from the position magnet 4.

[0037] The electronic chamber 3 also houses a DSP34 (Digital Signal Processor), which is electrically connected to a pulse current generating circuit 31 and a piezoelectric ceramic transducer 32. The DSP34 controls the transmission of interrogation pulses and performs digital signal processing on the detected echo signals to calculate displacement values. The electronic chamber 3 also contains a temperature sensor 35, which is connected to the DSP34. The DSP34 has a built-in sound velocity-temperature compensation algorithm, used to perform real-time temperature compensation on the displacement calculation results based on the readings from the temperature sensor 35.

[0038] A damper 21 is provided at the end of the waveguide wire 2. The acoustic impedance of the damper 21 is matched with that of the waveguide wire 2 to absorb stress wave energy and suppress end reflection. The coupling block 33 is made of a non-magnetic material with high hardness and high elastic modulus, preferably zirconia ceramic or tungsten carbide, with a hardness of not less than HRA90 and an elastic modulus of not less than 300 GPa. The piezoelectric ceramic transducer 32 is a piezoelectric ceramic element operating in shear mode, with a piezoelectric constant d15 of not less than 300 pC / N and a resonant frequency range of 100 kHz to 500 kHz.

[0039] The signal processing performed by the digital signal processor includes digital filtering, coherent integration, and time-to-digital conversion. The digital filtering uses an FIR filter with an adjustable cutoff frequency, and the coherent integration iterations range from 64 to 256. The probe assembly 1 is a sealed metal tube made of stainless steel or aluminum alloy with a wall thickness of 0.5 mm to 2 mm. The waveguide wire 2 is under tension inside the tube, with a preload of 50 N to 200 N. The electronic housing 3 is fixed to one end of the probe assembly 1 via threaded connection or welding. The housing 3 has an IP67 protection rating, and the internal circuit board is encapsulated in epoxy resin. The sensor also includes an output interface circuit 37, supporting analog and digital outputs. Analog outputs include 4-20mA or 0-10V, and digital outputs include an SSI interface or an RS485 interface.

[0040] This utility model mainly includes a measuring rod assembly 1, a waveguide wire 2, an electronic chamber 3, and a position magnet 4. Its core improvement lies in the integration of an integrated excitation and detection module, a digital signal processor (DSP34), a temperature sensor 35 and a compensation module within the electronic chamber 3, as well as an impedance matching damping structure at the end of the waveguide wire 2. The following is a detailed description of each component: Probe assembly 1: Consists of a sealed metal tube, serving as the sensor's housing and mechanical support. The metal tube is made of stainless steel (such as 304 or 316L) or aluminum alloy, with a wall thickness ranging from 0.5 mm to 2 mm, and is internally polished to reduce friction on the waveguide wire 2. The length of probe assembly 1 can be customized to meet stroke requirements, typically ranging from 100 mm to 5000 mm. The sealed design achieves an IP67 protection rating, preventing dust and moisture ingress.

[0041] Waveguide wire 2: Made of ferromagnetic magnetostrictive material, such as iron-cobalt alloy (Fe-Co, cobalt content 30%-50%), with a diameter typically ranging from 0.5 mm to 2 mm. Waveguide wire 2 is coaxially mounted within a metal tube and is preloaded with a tensioning mechanism at a force of 50 N to 200 N to maintain straightness and stress wave transmission efficiency. Waveguide wire 2 is fixed at both ends; one end is connected to the electron chamber 3, and the other end is connected to the damper 21.

[0042] Electronic housing 3: Fixed to one end of the probe assembly 1, typically mechanically secured via threaded connection or welding. The outer shell of electronic housing 3 is made of metal or engineering plastic, and it contains control and processing circuitry. Key components include: Integrated Excitation and Detection Module: This module integrates a pulse current generation circuit 31 and a piezoelectric ceramic transducer 32. The pulse current generation circuit 31, based on MOSFET or IGBT switching technology, generates narrow-width (0.1 μs to 10 μs) and high-amplitude (1A to 10 A) current pulses. The piezoelectric ceramic transducer 32 employs a shear-mode piezoelectric ceramic element (such as PZT-5A) with a piezoelectric constant d15 of not less than 300 pC / N, and a resonant frequency matching the stress wave frequency (100 kHz to 500 kHz). The transducer is mechanically coupled to the end of the waveguide wire 2 via a coupling block 33; the coupling block 33 is made of a high-hardness non-magnetic material, such as zirconia ceramic (hardness HRA93, elastic modulus 200 GPa) or tungsten carbide, ensuring efficient vibration transmission.

[0043] Digital Signal Processor (DSP34): Employs a high-performance DSP34 chip (such as TI's TMS320F28335) with a main frequency of no less than 150 MHz. The DSP34 is responsible for generating a high-precision interrogation pulse sequence and performing digital processing on the signal returned by the piezoelectric ceramic transducer 32, including digital filtering (FIR or IIR filter, with adjustable cutoff frequency), coherent integration (64-256 integration times), timestamp marking (1 ns resolution), and correlation operations to accurately extract the stress wave arrival time.

[0044] Temperature sensor 35 and compensation module: Temperature sensor 35 (such as PT100 platinum resistance thermometer or thermocouple) is attached to the inner wall of waveguide wire 2 or measuring rod to monitor temperature in real time. DSP34 has a built-in sound velocity-temperature characteristic curve (calibrated experimentally, such as v = k*T + b, where k is the temperature coefficient) to perform real-time software compensation for displacement values.

[0045] Output interface circuit 37: Supports multiple output modes, such as analog output (4-20 mA or 0-10 V) and digital output (SSI interface, RS485 or CAN bus), which facilitates integration with the host system.

[0046] Position magnet 4: Movably mounted outside the measuring rod assembly 1, typically a permanent magnet (such as neodymium iron boron) with a magnetic field strength of 0.1 T to 0.5 T. The position magnet 4 is not in contact with the waveguide wire 2, but is coupled to the measuring rod assembly 1 through a sliding bearing or guide rail, allowing for smooth movement.

[0047] Impedance matching and damping structure: A damper 21, made of sound-absorbing material (such as special rubber or polymer), is installed at the end of the waveguide wire 2. Its acoustic impedance is matched with that of the waveguide wire 2 (impedance ratio close to 1). The damper 21 is designed in a conical or stepped shape to maximize absorption efficiency and reduce reflected echoes to below -40 dB.

[0048] The working principle of this utility model is as follows: Excitation phase: DSP34 triggers pulse current generation circuit 31, generating current pulses to drive piezoelectric ceramic transducer 32. Due to the inverse piezoelectric effect, the transducer generates high-frequency shear vibration, which directly excites waveguide wire 2 through coupling block 33 to generate a pure torsional stress wave (main wave).

[0049] Propagation and Interaction: The main wave propagates along waveguide filament 2 at the speed of sound (approximately 3000 m / s). When it passes the position magnet 4, a second torsional stress wave (echo) is generated under the Villari effect.

[0050] Detection phase: The echo is transmitted back to terminal 3 of the electronic chamber and detected by the same piezoelectric ceramic transducer 32 (positive piezoelectric effect), converting it into an electrical signal. After amplification and filtering, the signal is processed by DSP34 to calculate the time difference Δt.

[0051] Displacement calculation: Displacement L = v × Δt / 2, where v is the speed of sound, output after temperature compensation.

[0052] In this embodiment, the non-contact magnetostrictive linear displacement sensor mainly consists of a probe assembly 1, a waveguide wire 2, an electronic housing 3, and a position magnet 4. The probe assembly 1 is a 2000 mm long stainless steel tube (material 304, wall thickness 1 mm), with a polished interior. The waveguide wire 2 is made of iron-cobalt alloy, with a diameter of 1 mm, and is pre-tensioned with 100 N through tensioning mechanisms at both ends, coaxially passing through the probe assembly 1. The electronic housing 3 is fixed to the left end of the probe assembly 1 via a threaded connection; its outer shell is made of aluminum alloy and has IP67 protection. The position magnet 4 is a neodymium iron boron magnet with a magnetic field strength of 0.3 T, fitted around the probe assembly 1, and can slide freely.

[0053] The control and processing circuit is based on a DSP34 (model TMS320F28335). The DSP34 periodically triggers a pulse current generation circuit 31, which is based on a MOSFET switch, to generate a current pulse with a width of 2μs and an amplitude of 5A. The current pulse is sent to the integrated excitation and detection module.

[0054] The integrated excitation and detection module includes a piezoelectric ceramic transducer 32 and a coupling block 33. The piezoelectric ceramic transducer 32 is a shear-mode PZT element (10 mm × 10 mm × 2 mm, resonant frequency 200 kHz), which is connected to the coupling block 33 by silver adhesive bonding. The coupling block 33 is made of zirconia ceramic (hardness HRA93) and is precision-machined and crimped to the end of the waveguide wire 2. When a current pulse is applied, the piezoelectric ceramic vibrates, exciting the waveguide wire 2 to generate a torsional stress wave.

[0055] The stress wave propagates to position magnet 4, generating an echo. The echo is detected by the same transducer, and the signal is amplified 1000 times by a signal conditioning circuit (including a low-noise amplifier and a bandpass filter) before being sent to DSP34. DSP34 performs digital filtering (FIR filter, cutoff frequency 150 kHz) and coherent integration (128 times) to accurately measure the time difference. Temperature sensor 35 (PT100) is attached near waveguide wire 2, and DSP34 compensates according to a pre-calibrated sound velocity-temperature curve (v = -0.5*T + 3000 m / s, T is degrees Celsius). The displacement value is output at 4-20 mA through output interface circuit 37.

[0056] A damper 21, made of butyl rubber, is installed at the end of the waveguide wire 2 to impedance match the waveguide wire 2, achieving an absorption efficiency of over 90%. In laboratory tests of this embodiment, with a stroke of 2000 mm, the accuracy reached ±0.1 mm, and the temperature drift was less than ±0.05 mm.

[0057] This novel sensor has been successfully applied in fields such as hydraulic cylinder position detection, CNC machine tools, injection molding machines, and wind power equipment. For example, in the hydraulic systems of steel plants, the sensor replaces traditional potentiometers, increasing lifespan tenfold and reducing maintenance costs. Future applications can be expanded to new fields such as smart homes and medical equipment.

[0058] The implementation principle of this utility model is as follows: This utility model discloses a non-contact magnetostrictive linear displacement sensor, relating to the field of displacement measurement technology. The sensor includes a measuring rod assembly 1, a waveguide wire 2, an electronic chamber 3, and a position magnet 4. Its improvement lies in the integration of an integrated excitation and detection module within the electronic chamber 3. This module includes a pulse current generating circuit 31 and a piezoelectric ceramic transducer 32, which are mechanically coupled to the end of the waveguide wire 2 via a coupling block 33, used to excite and detect torsional stress waves. The sensor also includes a digital signal processor (DSP 34), a temperature sensor 35, a compensation module, and an impedance-matching damper 21. This utility model solves the problems of large signal attenuation, weak anti-interference ability, high temperature sensitivity, and complex structure in existing technologies, possessing advantages such as high signal-to-noise ratio, simplified structure, good thermal stability, and strong anti-interference ability. It is suitable for long-stroke, high-precision measurement scenarios such as industrial automation and hydraulic cylinder position detection.

[0059] The embodiments described herein are preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape, and principle of this utility model should be included within the scope of protection of this utility model.

Claims

1. A non-contact magnetostrictive linear displacement sensor, comprising a probe assembly (1), a waveguide wire (2) coaxially disposed within the probe assembly (1), an electronic housing (3) fixed to one end of the probe assembly (1), and a position magnet (4) movably disposed outside the probe assembly (1), characterized in that: The electronic compartment (3) is equipped with an integrated excitation and detection module, which includes a pulse current generating circuit (31) and a piezoelectric ceramic transducer (32). The piezoelectric ceramic transducer (32) is mechanically coupled to the end of the waveguide wire (2) through a coupling block (33) to excite torsional stress waves to the waveguide wire (2) and detect the torsional stress waves returning from the position magnet (4).

2. The non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: The electronic compartment (3) is also equipped with a DSP (34), which is electrically connected to the pulse current generating circuit (31) and the piezoelectric ceramic transducer (32) to control the transmission of interrogation pulses and perform digital signal processing on the detected echo signals to calculate the displacement value.

3. A non-contact magnetostrictive linear displacement sensor according to claim 2, characterized in that: The electronic compartment (3) is also equipped with a temperature sensor (35), which is connected to the DSP (34). The DSP (34) has a built-in sound speed-temperature compensation algorithm, which is used to perform real-time temperature compensation on the displacement calculation results based on the reading of the temperature sensor (35).

4. A non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: A damper (21) is provided at the end of the waveguide wire (2), and the acoustic impedance of the damper (21) is matched with that of the waveguide wire (2) to absorb stress wave energy and suppress end reflection.

5. A non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: The coupling block (33) is made of a non-magnetic material with high hardness and high elastic modulus, such as zirconium oxide ceramic or tungsten carbide.

6. A non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: The piezoelectric ceramic transducer (32) is a piezoelectric ceramic element that operates in shear mode.

7. A non-contact magnetostrictive linear displacement sensor according to claim 2, characterized in that: The signal processing performed by the DSP (34) includes digital filtering, coherent integration, and time-to-digital conversion.

8. A non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: The probe assembly (1) is a sealed metal tube, and the waveguide wire (2) is in a taut state inside the tube.

9. A non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: The electronic compartment (3) is fixed to one end of the measuring rod assembly (1) by threaded connection or welding. The outer shell of the electronic compartment (3) has an IP67 protection rating, and the internal circuit board is encapsulated with epoxy resin.

10. A non-contact magnetostrictive linear displacement sensor according to claim 1, characterized in that: The sensor also includes an output interface circuit (37) that supports analog output and digital output. The analog output includes 4-20 mA or 0-10 V, and the digital output includes an SSI interface or an RS485 interface.

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