EP-4737864-A1 - HARSH ENVIRONMENT MAGNETOSTRICTIVE DISPLACEMENT SENSOR

EP4737864A1EP 4737864 A1EP4737864 A1EP 4737864A1EP-4737864-A1

Abstract

A sensor assembly of a magnetostrictive displacement sensor includes a waveguide, a pickup sensing element, a balanced line driver circuit and a cable connector. The pickup sensing element is configured to generate a high impedance sensor response signal through a positive pickup terminal and a negative pickup terminal in response to a magnetostrictive response in the waveguide. The balanced line driver circuit includes positive and negative response signal circuits respectively configured to produce a positive sensor signal at a low impedance and a negative sensor signal at a low impedance based on the high impedance sensor response signal at the positive and negative pickup terminals. The cable connector includes a positive sensor terminal coupled to the positive sensor signal and a negative sensor terminal coupled to the negative sensor signal.

Inventors

VIOLA, UWE
Minin, Aleksey
ANTHONY, Jacob

Assignees

Temposonics, LLC

Dates

Publication Date: 20260506
Application Date: 20251105

Claims (15)

A magnetostrictive displacement sensor including a sensor assembly comprising: a waveguide; a pickup sensing element configured to generate a high impedance sensor response signal through a positive pickup terminal and a negative pickup terminal in response to a magnetostrictive response in the waveguide corresponding to a target magnet; a signal conditioner comprising a balanced line driver circuit including: a positive response signal circuit configured to produce a positive sensor signal at a low impedance based on the high impedance sensor response signal at the positive pickup terminal; and a negative response signal circuit configured to produce a negative sensor signal at a low impedance based on the high impedance sensor response signal at the negative pickup terminal; and a cable connector including a positive sensor terminal coupled to the positive sensor signal and a negative sensor terminal coupled to the negative sensor signal, wherein, when a cable is connected to the cable connector, the balanced line driver circuit decouples the positive and negative pickup terminals from a capacitance of the cable.
The magnetostrictive displacement sensor according to claim 1, wherein the positive and negative response signal circuits form a differential buffer, and preferably, wherein the signal conditioner includes a bandpass filter configured to pass frequencies of the sensor response signal within a range of about 100 kHz to 650 kHz to the balanced line driver circuit.
The magnetostrictive displacement sensor according to any of the preceding claims, wherein: the positive response signal circuit comprises a first inverted operational amplifier having a first negative input terminal coupled to the positive pickup terminal, and a first positive input terminal connected to a reference voltage, the first inverted operational amplifier configured to amplify the high impedance sensor response signal at a first gain to produce the positive sensor signal; and the negative response signal circuit comprises a second inverted operational amplifier having a second negative input terminal coupled to the negative pickup terminal, and a second positive input terminal connected to a reference voltage, the second inverted operational amplifier configured to amplify the high impedance sensor response signal at a first gain to produce the negative sensor signal.
The magnetostrictive displacement sensor according to any of claims 1 or 2 wherein: the positive response signal circuit comprises a first non-inverted operational amplifier having a first positive input terminal coupled to the positive pickup terminal and a first negative input terminal, the first non-inverted operational amplifier configured to amplify the high impedance sensor response signal at a first gain to produce the positive sensor signal, which is fed back to the first negative input terminal; and the negative response signal circuit comprises a second non-inverted operational amplifier having a second positive input terminal coupled to the negative pickup terminal and a second negative input terminal, the second non-inverted operational amplifier configured to amplify the high impedance sensor response signal at a first gain to produce the negative sensor signal, which is fed back to the second negative input terminal.
The magnetostrictive displacement sensor according to claim 3 or 4, wherein the first gain is set to about 3 to 10.
The magnetostrictive displacement sensor according to any one of the preceding claims, including: a cable attached to the cable connector and including a positive response wire connected to the positive sensor terminal, a negative response wire connected to a negative sensor terminal, and a waveguide wire coupled to a waveguide terminal of the cable connector that is connected to the waveguide, and in one embodiment, wherein a length of the cable is greater than about 3 meters; and sensor electronics comprising: an excitation generator configured to generate a current pulse that is delivered to the waveguide through the waveguide wire of the cable; a receiver circuit configured to receive the positive sensor signal from the positive response wire and the negative sensor signal from the negative sensor wire and output a received sensor signal, and in one embodiment, wherein the receiver circuit comprises a transformer; and a controller configured to generate a position estimate of the target magnet relative to the waveguide based on the received sensor signal.
A magnetostrictive displacement sensor comprising: a target magnet; a sensor assembly comprising a waveguide; a pickup sensing element configured to generate a high impedance sensor response signal through a positive pickup terminal and a negative pickup terminal in response to a magnetostrictive response in the waveguide corresponding to the target magnet; a signal conditioner comprising a balanced line driver circuit including: a positive response signal circuit configured to produce a positive response signal at a low impedance based on the high impedance sensor response signal at the positive pickup terminal; and a negative response signal circuit configured to produce a negative sensor signal at a low impedance based on the high impedance sensor response signal at the negative pickup terminal; and a cable connector including a positive sensor terminal coupled to the positive sensor signal, a negative sensor terminal coupled to the negative sensor signal, and a waveguide terminal coupled to the waveguide; a cable attached to the cable connector and including a positive response wire connected to the positive sensor terminal, a negative response wire connected to a negative sensor terminal, and a waveguide wire coupled to the waveguide terminal; and sensor electronics comprising: an excitation generator configured to generate a current pulse that is delivered to the waveguide through the waveguide wire of the cable; a receiver circuit configured to receive the positive sensor signal from the positive response wire and the negative sensor signal from the negative sensor wire and output a received sensor signal; and a controller configured to generate a position estimate of the target magnet relative to the waveguide based on the received sensor signal.
The magnetostrictive displacement sensor according to claim 7, wherein the positive and negative response signal circuits form a differential buffer.
The magnetostrictive displacement sensor according to any one of claims 7 or 8, wherein: the positive response signal circuit comprises a first inverted operational amplifier having a first negative input terminal coupled to the positive pickup terminal, and a first positive input terminal connected to a reference voltage, the first inverted operational amplifier configured to amplify the high impedance sensor response signal at a gain to produce the positive sensor signal; and the negative response signal circuit comprises a second inverted operational amplifier having a second negative input terminal coupled to the negative pickup terminal, and a second positive input terminal connected to a reference voltage, the second inverted operational amplifier configured to amplify the high impedance sensor response signal at the gain to produce the negative sensor signal.
The magnetostrictive displacement sensor according to any one of claims 7 or 8, wherein: the positive response signal circuit comprises a first non-inverted operational amplifier having a first positive input terminal coupled to the positive pickup terminal and a first negative input terminal, the first non-inverted operational amplifier configured to amplify the high impedance sensor response signal at a gain to produce the positive sensor signal, which is fed back to the first negative input terminal; and the negative response signal circuit comprises a second non-inverted operational amplifier having a second positive input terminal coupled to the negative pickup terminal and a second negative input terminal, the second non-inverted operational amplifier configured to amplify the high impedance sensor response signal at the gain to produce the negative sensor signal, which is fed back to the second negative input terminal.
The magnetostrictive displacement sensor according to claims 9 or 10, wherein the gain is set to about 3 to 10.
The magnetostrictive displacement sensor according to claims 7 to 11, wherein the signal conditioner includes a bandpass filter configured to pass frequencies of the sensor response signal within a range of about 100 kHz to 650 kHz to the balanced line driver circuit.
The magnetostrictive displacement sensor according to any one of claims 7 to 12, wherein the receiver circuit comprises a transformer.
The magnetostrictive displacement sensor according to any one of claims 7 to 13, wherein a length of the cable is greater than about 3 meters.
A method of operating magnetostrictive displacement sensor, the magnetostrictive displacement sensor comprising: a target magnet; a sensor assembly comprising a waveguide; a pickup sensing element; a signal conditioner comprising a balanced line driver circuit including: a positive response signal circuit; and a negative response signal circuit; and a cable connector including a positive sensor terminal, a negative sensor terminal and a waveguide terminal; sensor electronics comprising: an excitation generator; a receiver circuit; and a controller, the method comprising: connecting a positive response wire of a cable to the positive sensor terminal, a negative response wire of the cable to the negative sensor terminal, and a waveguide wire of the cable to the waveguide terminal; delivering a current pulse generated using the excitation generator to the waveguide through the waveguide wire and the waveguide terminal; generating a magnetostrictive response in the waveguide at a location of a target magnet in response to the current pulse in the waveguide; generating a high impedance sensor response signal to the magnetostrictive response through a positive pickup terminal and a negative pickup terminal of the pickup sensing element; converting the high impedance sensor response signal at the positive pickup terminal to a low impedance positive sensor signal using the positive response signal circuit; converting the high impedance negative sensor signal to low impedance negative sensor signal using the negative response signal circuit; delivering the low impedance positive sensor signal to the receiver circuit through the positive response wire and the low impedance negative sensor signal to the receiver circuit through the negative response wire; generating a received sensor signal based on the low impedance positive sensor signal and the low impedance negative sensor signal using the receiver circuit; and determining a position estimate of the location of the target magnet relative to the waveguide based on the received sensor signal using the controller.

Description

CROSS-REFERENCE RELATED APPLICATION(S) The present application is based on and claims the benefit of U.S. provisional patent application Serial No. 63/716,512, filed November 5, 2024, the content of which is hereby incorporated by reference in its entirety. FIELD Embodiments of the present disclosure generally relate to magnetostrictive displacement sensors, and more specifically, to magnetostrictive displacement sensors that are suitable for displacement measurements within harsh environments. BACKGROUND Magnetostrictive displacement sensors are robust, high resolution instruments which have proven to be useful in many measurement and control applications. Magnetostrictive displacement sensors generally include a sensor assembly, a target magnet and sensor electronics. The sensor assembly generally includes a waveguide (e.g., conductive wire) and a pickup. The target magnet has a variable position along the waveguide corresponding to the position to be measured. The sensor electronics includes an excitation generator circuit that generates an excitation signal, such as a current pulse, which is conducted through the waveguide. The excitation signal creates a magnetic field around the waveguide that interacts with the magnetic field of the target magnet to create a magnetostrictive response in the waveguide at the location of the target magnet. The magnetostrictive response takes the form of a sonic wave having mechanical pulse components including a longitudinal wave corresponding to a compression of the waveguide along its longitudinal axis, and a torsional wave corresponding to a torsional strain on the surface of the waveguide around the longitudinal axis. The pickup is located at an end of the waveguide and includes a transducer or sensing element that is used to detect the longitudinal wave or torsional wave by converting the wave into an electrical response signal. The sensor electronics is configured to process the electrical response signal to determine the position of the target magnet based on a time of flight measurement between the excitation signal and a detection of the longitudinal wave or the torsional wave in the electrical response signal. Some applications for magnetostrictive displacement sensors include harsh industrial environments, such as a high temperature environment (e.g., 105-120 °C), which may be found in steel mills and other industries. While the sensor assembly may be able to withstand such high temperature environments, the sensor electronics cannot. For example, the temperature range that is suitable for the sensor electronics may have an upper limit of only 70-80 °C. As a result, in order for a conventional magnetostrictive displacement sensor to be used in such high temperature environments (e.g., greater than 60 °C), the sensor electronics must be protected from the environment. Some magnetostrictive displacement sensors, such as the R-Series Model RD4 sensor produced by Temposonics, address this problem by separating the sensor assembly and the sensor electronics from each other and linking the components through a cable. This allows the sensor assembly to make the desired displacement measurements within the high temperature environment while the sensor electronics may be positioned in a safer location. Unfortunately, the length of the cable that may be used to connect the sensor assembly from the sensor electronics must be quite short (e.g., less than 0.5 meters) to limit distortion of the electrical response signal by the capacitance of the cable. As a result, the sensor electronics cannot generally be remotely displaced a significant distance away from the high temperature environment in which the sensor assembly is placed. Instead, the short cable length generally only allows the sensor electronics to be isolated within a protective housing located within the high temperature environment that prevents the sensor electronics from overheating. As a result, users must generally access the high temperature environment during setup and use of the sensor electronics. SUMMARY Embodiments of the present disclosure generally relate to magnetostrictive displacement sensors, and more specifically, to magnetostrictive displacement sensors that are suitable for displacement measurements within harsh environments and methods of operating the magnetostrictive displacement sensors. In some embodiments, the magnetostrictive displacement sensor includes a sensor assembly comprising a waveguide, a pickup sensing element, a signal conditioner and a cable connector. The pickup sensing element is configured to generate a high impedance sensor response signal through a positive pickup terminal and a negative pickup terminal in response to a magnetostrictive response in the waveguide corresponding to a target magnet. The signal conditioner includes a balanced line driver circuit comprising a positive response signal circuit configured to produce a positive sensor signal at a low impedanc