Magnetostrictive displacement sensor for harsh environments

Abstract

This invention provides a magnetostrictive displacement sensor suitable for measuring displacement in harsh environments, and a method for operating the magnetostrictive displacement sensor. [Solution] The sensor assembly 102 of the magnetostrictive displacement sensor 100 includes a waveguide 106, a pickup detection element, a balanced line driver circuit 176, and a cable connector 184. The pickup detection element is configured to generate a high-impedance sensor response signal via a positive pickup terminal 177 and a negative pickup terminal 178 in response to the magnetostrictive response in the waveguide. The balanced line driver circuit includes positive and negative response signal circuits 180, respectively, configured to generate a low-impedance positive sensor signal 144P and a low-impedance negative sensor signal 144N based on the high-impedance sensor response signals at the positive and negative pickup terminals. The cable connector includes a positive sensor terminal 186 connected to the positive sensor signal and a negative sensor terminal 188 connected to the negative sensor signal.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of, and incorporates by reference in its entirety, U.S. Provisional Patent Application Serial No. 63 / 716512, filed on November 5, 2024.

[0002] Technical Field Embodiments of the present disclosure generally relate to magnetostrictive displacement sensors, and more particularly to magnetostrictive displacement sensors suitable for displacement measurement in harsh environments.

Background Art

[0003] Magnetostrictive displacement sensors are robust and high - resolution devices that have proven useful in numerous measurement and control applications. Magnetostrictive displacement sensors generally include a sensor assembly, a target magnet, and sensor electronics.

[0004] The sensor assembly generally includes a waveguide (e.g., a conductive wire) and a pickup. The target magnet has a variable position along the waveguide corresponding to the position being measured. The sensor electronics include an excitation generator circuit that generates an excitation signal such as a current pulse transmitted through the waveguide.

[0005] The excitation signal generates a magnetic field around the waveguide that interacts with the magnetic field of the target magnet, causing a magnetostrictive response at the position of the target magnet in the waveguide. The magnetostrictive response takes the form of an acoustic wave with a mechanical pulse component that includes a longitudinal wave corresponding to compression of the waveguide along its longitudinal axis and a torsional wave corresponding to torsional strain on the surface of the waveguide with respect to the longitudinal axis. The pickup is provided at the end of the waveguide and includes a transducer or a sensing element. The transducer or sensing element is used to detect the longitudinal or torsional wave by converting the wave into an electrical response signal.

[0006] The sensor electronic circuit is configured to process the electrical response signal and determine the position of the target magnet based on the propagation time measurement between the excitation signal and the detection of longitudinal or torsional waves in the electrical response signal. [Overview of the project] [Problems that the invention aims to solve]

[0007] Some applications for magnetostrictive displacement sensors involve harsh industrial environments, such as high-temperature environments (e.g., 105-120°C), which can be found in steel mills and other industries. While the sensor assembly may be able to withstand such high temperatures, the sensor's electronic circuitry may not. For example, the suitable temperature range for sensor electronic circuitry may have an upper limit of only 70-80°C. Consequently, for conventional magnetostrictive displacement sensors to be used in such high-temperature environments (e.g., above 60°C), the sensor's electronic circuitry must be protected from the environment.

[0008] Some magnetostrictive displacement sensors, such as the R-series Model RD4 sensor manufactured by TempoSonics, address this problem by isolating the sensor assembly and sensor electronics from each other and linking the components via cables. This allows the sensor assembly to perform the desired displacement measurements in high-temperature environments while placing the sensor electronics in a safer location.

[0009] Unfortunately, the length of the cables used to connect the sensor electronics to the sensor assembly must be very short (e.g., less than 0.5 meters) to limit distortion of the electrical response signal due to cable capacitance. As a result, the sensor electronics cannot generally be located at a significant distance 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 inside a protective enclosure located within the high-temperature environment to prevent overheating. Consequently, the user generally has to access the high-temperature environment during the setup and use of the sensor electronics. [Means for solving the problem]

[0010] Embodiments of this disclosure generally relate to magnetostrictive displacement sensors, and more specifically to magnetostrictive displacement sensors suitable for measuring displacement in harsh environments, and methods for operating the magnetostrictive displacement sensors.

[0011] In some embodiments, the magnetostrictive displacement sensor includes a sensor assembly comprising a waveguide, a pickup detection element, a signal conditioner, and a cable connector. The pickup detection element is configured to generate a high-impedance sensor response signal via a positive pickup terminal and a negative pickup terminal in response to the 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 generate a low-impedance positive sensor signal based on the high-impedance sensor response signal at the positive pickup terminal, and a negative response signal circuit configured to generate a low-impedance negative sensor signal based on the high-impedance sensor response signal at the negative pickup terminal. The cable connector includes a positive sensor terminal connected to the positive sensor signal and a negative sensor terminal connected to the negative sensor signal. The balanced line driver circuit decouples the positive and negative pickup terminals from the capacitance of the cable connected to the cable connector. Further embodiments of the magnetostrictive displacement sensor include one or more of the embodiments described below.

[0012] According to one embodiment, the positive and negative response signal circuits form a differential buffer.

[0013] According to one embodiment, The positive response signal circuit includes a first inverting operational amplifier having a first negative input terminal connected to a positive pickup terminal and a first positive input terminal connected to a reference voltage, and the first inverting operational amplifier is configured to amplify a high-impedance sensor response signal with a first gain to generate a positive sensor signal. The negative response signal circuit includes a second inverting operational amplifier having a second negative input terminal connected to a negative pickup terminal and a second positive input terminal connected to a reference voltage, and is configured to amplify a high-impedance sensor response signal with a first gain to generate a negative sensor signal.

[0014] According to one embodiment, the first gain is set to approximately 3 to 10.

[0015] According to one embodiment, The positive response signal circuit includes a first non-inverting operational amplifier having a first positive input terminal connected to a positive pickup terminal and a first negative input terminal, and is configured to amplify a high-impedance sensor response signal with a first gain to generate a positive sensor signal, and to feed the positive sensor signal back to the first negative input terminal. The negative response signal circuit includes a second non-inverting operational amplifier having a second positive input terminal connected to a negative pickup terminal and a second negative input terminal, and is configured to amplify a high-impedance sensor response signal with a first gain to generate a negative sensor signal, and to feed the negative sensor signal back to the second negative input terminal.

[0016] According to one embodiment, the first gain is set to approximately 3 to 10.

[0017] According to one embodiment, the signal conditioner includes a band-pass filter configured to pass a sensor response signal with a frequency in the range of approximately 100 kHz to 650 kHz through a balanced line driver circuit.

[0018] According to one embodiment, the magnetostrictive displacement sensor includes a cable and a sensor electronic circuit. The cable is attached to a cable connector and includes a positive response wire connected to a positive sensor terminal, a negative response wire connected to a negative sensor terminal, and a waveguide wire connected to the waveguide terminal of the cable connector, which is connected to a waveguide. The sensor electronic circuit includes an excitation generator configured to generate current pulses transmitted to the waveguide via the waveguide wire of the cable, a receiver circuit configured to receive a positive sensor signal from the positive response wire and a negative sensor signal from the negative sensor wire and output a received sensor signal, and a controller configured to generate an estimated position of a target magnet with respect to the waveguide based on the received sensor signal.

[0019] According to one embodiment, the receiver circuit includes a transformer.

[0020] According to one embodiment, the length of the cable is greater than approximately 3 meters.

[0021] Another embodiment of the magnetostrictive displacement sensor includes a target magnet, a sensor assembly, a cable, and a sensor electronic circuit. The sensor assembly includes a waveguide, a pickup detection element, a signal conditioner, and a cable connector. The pickup detection element is configured to generate a high-impedance sensor response signal via a positive pickup terminal and a negative pickup terminal in response to the magnetostrictive response in the waveguide corresponding to the target magnet. The balanced line driver circuit of the signal conditioner includes a positive response signal circuit configured to generate a low-impedance positive response signal based on the high-impedance sensor response signal at the positive pickup terminal, and a negative response signal circuit configured to generate a low-impedance negative sensor signal based on the high-impedance sensor response signal at the negative pickup terminal. The cable connector includes a positive sensor terminal connected to the positive sensor signal, a negative sensor terminal connected to the negative sensor signal, and a waveguide terminal connected to the waveguide. The cable is attached to the cable connector and includes a positive response wire connected to the positive sensor terminal, a negative response wire connected to the negative sensor terminal, and a waveguide wire connected to the waveguide terminal. The sensor electronic circuit includes an excitation generator configured to generate current pulses transmitted to the waveguide via the waveguide wires of the cable; a receiver circuit configured to receive a positive sensor signal from a positive response wire and a negative sensor signal from a negative sensor wire, and to output a received sensor signal; and a controller configured to generate an estimated position of a target magnet relative to the waveguide based on the received sensor signal. Further embodiments of the magnetostrictive displacement sensor include one or more of the embodiments described below.

[0022] According to one embodiment, the positive and negative response signal circuits form a differential buffer.

[0023] According to one embodiment, The positive response signal circuit includes a first inverting operational amplifier having a first negative input terminal connected to a positive pickup terminal and a first positive input terminal connected to a reference voltage, and the first inverting operational amplifier is configured to amplify a high-impedance sensor response signal with a predetermined gain to generate a positive sensor signal. The negative response signal circuit is a second inverting operational amplifier having a second negative input terminal connected to the negative pickup terminal and a second positive input terminal connected to the reference voltage, and is configured to amplify the high-impedance sensor response signal by a gain to generate a negative sensor signal, and includes a second inverting operational amplifier.

[0024] According to one embodiment, the gain is set to about 3 to 10.

[0025] According to one embodiment, The positive response signal circuit is a first non-inverting operational amplifier having a first positive input terminal connected to the positive pickup terminal and a first negative input terminal, and is configured to amplify the high-impedance sensor response signal by a predetermined gain to generate a positive sensor signal, and the positive sensor signal is fed back to the first negative input terminal, and includes a first non-inverting operational amplifier. The negative response signal circuit is a second non-inverting operational amplifier having a second positive input terminal connected to the negative pickup terminal and a second negative input terminal, and is configured to amplify the high-impedance sensor response signal by a gain to generate a negative sensor signal, and the negative sensor signal is fed back to the second negative input terminal, and includes a second non-inverting operational amplifier.

[0026] According to one embodiment, the gain is set to about 3 to 10.

[0027] According to one embodiment, the signal conditioner includes a band-pass filter configured to pass the frequency of the sensor response signal within the range of about 100 kHz to 650 kHz to the balanced line driver circuit.

[0028] According to one embodiment, the receiver circuit includes a transformer.

[0029] According to one embodiment, the length of the cable is greater than about 3 meters.

[0030] In one embodiment of a method for operating a magnetostrictive displacement sensor, the magnetostrictive displacement sensor includes a target magnet, a sensor assembly, and a sensor electronic circuit. The sensor assembly includes a waveguide, a pickup detection element, a signal conditioner, and a cable connector. The signal conditioner has a balanced line driver circuit including a positive response signal circuit and a negative response signal circuit, and the cable connector includes a positive sensor terminal, a negative sensor terminal, and a waveguide terminal. The sensor electronic circuit includes an excitation generator, a receiver circuit, and a controller. In this method, the positive response wire of the cable is connected to the positive sensor terminal, the negative response wire of the cable is connected to the negative sensor terminal, and the waveguide wire of the cable is connected to the waveguide terminal. A current pulse generated using the excitation generator is transmitted to the waveguide via the waveguide wire and waveguide terminal. In response to the current pulse in the waveguide, a magnetostrictive response is generated in the waveguide at the location of the target magnet. A high-impedance sensor response signal to the magnetostrictive response is generated via the positive and negative pickup terminals of the pickup detection element. The high-impedance sensor response signal at the positive pickup terminal is converted to a low-impedance positive sensor signal using a positive response signal circuit. The high-impedance negative sensor signal is converted to a low-impedance negative sensor signal using a negative response signal circuit. The low-impedance positive sensor signal is transmitted to the receiver circuit via a positive response wire, and the low-impedance negative sensor signal is transmitted to the receiver circuit via a negative response wire. The receiver circuit generates a received sensor signal based on the low-impedance positive sensor signal and the low-impedance negative sensor signal. The controller determines the estimated position of the target magnet relative to the waveguide based on the received sensor signal. In some further embodiments of this method, the magnetostrictive displacement sensor includes one or more of the embodiments described later.

[0031] This summary is provided in a simplified form to introduce the selection of concepts, which are further described in embodiments for carrying out the inventions described below. This summary is not intended to identify any key or essential features of the subject matter, nor is it intended to be used to help determine the scope of the subject matter. The subject matter described in the claims is not limited to embodiments that solve any or all of the defects described in the background. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic diagram of one embodiment of a magnetostrictive displacement sensor according to the present disclosure. [Figure 2] This is a simplified circuit diagram of one embodiment of a magnetostrictive displacement sensor according to the present disclosure. [Figure 3A] This is an isometric view of an embodiment of the pickup according to the present disclosure. [Figure 3B] This is an isometric view of an embodiment of the pickup according to the present disclosure. [Figure 3C] This is an isometric view of an embodiment of the pickup according to the present disclosure. [Figure 3D] This is an isometric view of an embodiment of the pickup according to the present disclosure. [Figure 4] This is a simplified circuit diagram of an embodiment of a balanced line driver circuit according to the present disclosure. [Figure 5] This is a simplified circuit diagram of an embodiment of a balanced line driver circuit according to the present disclosure. [Figure 6] This is a simplified circuit diagram of one embodiment of a receiver circuit according to the present disclosure. [Figure 7] This flowchart shows a method for operating a magnetostrictive displacement sensor according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0033] Embodiments of the present disclosure are described more thoroughly below with reference to the accompanying drawings. Components identified by the same or similar reference numerals indicate the same or similar components. However, various embodiments of the present disclosure may be carried out in numerous different forms and should not be construed as being limited to the specific embodiments described herein. Rather, the embodiments are described in a manner that makes the present disclosure detailed and complete and that fully conveys the scope of the embodiments to those skilled in the art.

[0034] Figures 1 and 2 are schematic and simplified circuit diagrams, respectively, of an embodiment of a magnetostrictive displacement sensor (MDS) 100 according to the present disclosure. The MDS 100 includes a sensor assembly 102 and a sensor electronic circuit 104. The sensor assembly 102 includes a magnetoelastic wire called a waveguide 106 and a pickup.

[0035] At least one target magnet 108 is provided near the waveguide 106 and has an adjustable position 112 along the axis 110 of the waveguide 106, as indicated by the arrow 113. The target magnet 108 may be in the form of a bar magnet provided along the waveguide 106, a ring magnet surrounding the waveguide 106, or other suitable form. The MDS 100 is generally configured to measure the position 112 of the target magnet 108 along the waveguide 106 with respect to a reference position 114.

[0036] The sensor electronic circuit 104 includes a controller 116 having one or more processors 118 and an excitation generator circuit 120 connected to the waveguide 106. As shown in Figure 1, a closed electrical circuit may be formed by the excitation generator circuit 120, the waveguide 106, and a return wire 122 connecting the distal end 124 of the waveguide 106 to the sensor electronic circuit 104, such as the excitation generator circuit 120. The controller 116 uses the excitation generator circuit 120 to generate a current pulse 126 to be transmitted to the proximal end 128 of the waveguide 106. An amplifier 130 (Figure 2) of the sensor electronic circuit 104 may be used to amplify the current pulse 126 before applying it to the waveguide 106.

[0037] As shown in Figure 1, the transmission of a current pulse 126 through the waveguide 106 generates a magnetic field 131, which interacts with the magnetic field 132 of the magnet 108 to generate a mechanical magnetostrictive response (e.g., sound wave) 134 in the waveguide 106. The magnetostrictive response 134 includes a longitudinal wave 134A (e.g., longitudinal compression) and a torsional wave 134B (e.g., torsional strain).

[0038] The magnetostrictive response 134 propagates along the waveguide 106 from both sides of the magnet 108. For example, a portion of the magnetostrictive response 134 may propagate along the waveguide 106 from position 112 of the magnet 108 toward end 124, and possibly to a damper (not shown) that reduces or eliminates the backpropagation of the acoustic wave 134 through the waveguide 106. Furthermore, a portion of the magnetostrictive response 134 propagates from position 112 of the magnet 108 toward end 128, where a magnetostrictive response pickup 140 is used to detect the magnetostrictive response 134, such as a longitudinal wave 134A and / or a torsional wave 134B.

[0039] The pickup 140 includes one or more sensing elements 142 configured to detect the magnetostrictive response 134 and generate at least one electrical sensor response signal 144 based on the magnetostrictive response 134. That is, one or more electrical response signals 144 include an index for a longitudinal wave 134A and / or an index for a torsional wave 134B. One or more indices may include, for example, transient changes or pulses in the magnitude of the signal 144. The position 112 of the target magnet 108 may be determined using the prior art by detecting the indices by the controller 116, based on the time from when the current pulse 126 is generated until when the index of the magnetostrictive response 134 is detected in the signal 144.

[0040] A signal conditioner 146 for the pickup 140 may be used, as shown in Figure 2, to isolate the detection element 142 from electrical interference, further adjust the signal 144 (e.g., by amplifying, rectifying, filtering, etc.), and then transmit the adjusted signal 144 to the sensor electronic circuit 104. For example, the signal conditioner may include a band-pass filter 147 that isolates the frequencies of the signal 144 corresponding to an expected magnetostrictive response index, such as a frequency range of approximately 100 kHz–650 kHz.

[0041] Accordingly, in some embodiments, the response signal 144 adjusted from the pickup 140 may be the original signal 144 generated by one or more detection elements 142, for example, if the pickup 140 does not include a signal conditioner 146, or it may be the response signal 144 after it has been adjusted or processed by the circuit of the signal conditioner 146.

[0042] The detection element 142 may take any suitable form. Figures 3A to 3D are isometric views of embodiments of pickups 140A to 140D according to the present disclosure. An exemplary detection element 142A, as shown in Figure 3A, includes a coil 150 attached to a waveguide 106, for example, via a rigid member 152. A magnet 154 has a magnetic field surrounding the coil 150. When a magnetostrictive response 134 (e.g., a longitudinal or torsional wave) propagating through the waveguide 106 reaches the member 152, the vibration of the member 152 causes relative motion between the magnetic field and the coil 150. The magnetic field induces a current pulse in the coil 150, which forms an index of the response 134 in the sensor response signal 144 propagating through the coil 150. The signal 144 from the coil 150 may be processed by a signal conditioner 146 before reaching the controller 116 (Figure 2).

[0043] One alternative to this configuration is to form a member 152 from a magnetic material and support the coil 150 in such a way that the magnetic member 152 can move relative to the coil 150. Thus, when the magnetic member 152 vibrates in response to the magnetostrictive response 134, the movement of the magnetic field relative to the coil 150 induces a corresponding current pulse index in the sensor response signal 144 from the coil 150.

[0044] The detection element 142 may include a conductive coil 150 wound around the waveguide 106 to form an exemplary detection element 142B shown in Figure 3B, or the conductive coil 150 may be positioned in a plane generally perpendicular to the waveguide 106 to form an exemplary detection element 142C shown in Figure 3C. In each case, the magnetostrictive response 134 propagating through the waveguide induces a current pulse or index in the sensor response signal 144 propagating through the coil 150.

[0045] The exemplary detection element 142D shown in Figure 3D comprises a piezoelectric material 158 connected to a waveguide 106, configured to physically strain in response to a magnetostrictive response 134. The strain in the piezoelectric material 158 generates a current pulse in the sensor response signal 144, which forms an index of the response 134. The piezoelectric material 158 may be exposed to the magnetostrictive response 134, for example, via a piezoelectric material 158A connected to the waveguide side via a rigid member 159, or via a piezoelectric material 158B connected to or following the waveguide of the waveguide.

[0046] The sensor electronic circuit 104 may process one or more response signals 144 using any suitable technique. The sensor electronic circuit 104 may include a signal conditioner 160 instead of, or in addition to, the signal conditioner 146 of the pickup 140. Similar to the case where the signal conditioner 146 is used, the signal conditioner 160 includes a circuit that generates a processed or received sensor signal 148 by amplifying, rectifying, filtering, and / or performing other processing on the response signal 144. Accordingly, the signal conditioner 146 may include, for example, a band-pass filter that replaces or adds to the band-pass filter 147 of the sensor assembly 102 and operates to isolate a frequency band (e.g., about 100 kHz to 650 kHz) corresponding to the magnetostrictive response index in the response signal 144.

[0047] In one embodiment, the controller includes an analog-to-digital converter (ADC) 161 that converts the sensor signal 148 into a corresponding digital sample. For example, the ADC 161 may sample each of one or more analog response signals 148 at a predetermined frequency, which allows the sensor signal 148 to be further processed by the controller 116. The digital sample of each sensor signal 148 may be stored in a non-temporary memory 162, which represents, for example, the computer-readable memory (e.g., flash memory, optical data storage device, magnetic data storage device, etc.) of a measuring device (e.g., a processing level transmitter) utilizing the sensor electronic circuit 104, the sensor assembly 102, and / or the MDS 100.

[0048] The sensor electronic circuit 104 may include a clock generator 164 that initiates a timing routine when the excitation generator circuit 120 generates a current pulse 126. The clock generator 164 may be used, according to the prior art, for example, by allocating the time of each digital sample of the sensor signal 148 to determine the time of the detected indicator in the sensor signal 148 for the generation of the current pulse 126.

[0049] One or more processors 118 of the controller 116 control components of the MDS 100 (e.g., the excitation generator circuit 120) and / or perform one or more functions described herein in response to the execution of program instructions and calibration parameters stored in memory 162. Each processor 118 of the controller 116 may comprise, for example, one or more computer-based systems, control circuits, microprocessor-based engine control systems, and / or programmable hardware components (e.g., field-programmable gate arrays). Although the controller 116 is shown as a component of the sensor electronic circuit 104, it should be understood that the controller 116 may represent one or more controllers and processors used internally in the measuring device to perform one or more functions described herein.

[0050] In some embodiments, at least one processor 118 is configured to detect indicators for longitudinal waves 134A and / or torsional waves 134B by analyzing the sensor signal 148 or a digital sample thereof. The position 112 of the target magnet 108 may be determined by one or more processors 118 in accordance with the prior art, based on the elapsed time from the generation of the current pulse 126 to the reception of the indicator in the sensor signal 148 and the known velocity of the corresponding longitudinal acoustic wave 134A or torsional acoustic wave 134B passing through the waveguide 106, which may be specified by calibration parameters. The controller 116 may output a position estimate 166 indicating the calculated position 112 of the target magnet 108.

[0051] Embodiments of the present disclosure include features that facilitate connecting the sensor electronic circuit 104 to the sensor assembly 102 via a long cable 170, such as a cable 172 having a length of about 10 meters or more, for example, about 10 to 30 m or up to 100 m, as shown in Figure 2. This allows the sensitive sensor electronic circuit 104 to be located remotely from a harsh industrial environment 174, such as a high-temperature environment (e.g., above 70°C), where the sensor assembly 102 is positioned to perform displacement measurements. Thus, the long cable may be used to position the sensor electronic circuit 104 in a separate environment 176 that is suitable for its operation and accessible to an operator, such as a room away from the harsh industrial environment 174, thereby eliminating the need to install the sensor electronic circuit 104 in a protective enclosure within the harsh environment 174.

[0052] The sensing element 142 (e.g., coil 150) of the pickup 140 generates a response signal 144 with a high impedance (e.g., 100 kilohms). This is generally unsuitable for transmission over cables longer than 1 meter. In some embodiments, the signal conditioner 146 includes a balanced line driver circuit 176. The balanced line driver circuit 176 is generally configured to convert the sensor response signal 144 from high impedance to a low impedance (e.g., 100 ohms) suitable for transmission over long cables 170. Furthermore, embodiments of the circuit 176 decouple the positive pickup terminal 177 and negative pickup terminal 178 of the pickup 140 from the capacitance of the cable 170. Otherwise, the capacitance of the cable 170 would distort the response signal 144, making it unsuitable for the sensor electronics circuit 104 to accurately determine the position estimate 166.

[0053] In one embodiment, the balanced line driver circuit 176 includes a positive response signal circuit 180 configured to generate a low-impedance positive sensor signal 144P based on a sensor response signal 144 (positive response signal) at or received from a positive pickup terminal 177, and a negative response signal circuit 182 configured to generate a low-impedance negative sensor signal 144N based on a sensor response signal 144 (negative response signal) at or received from a negative pickup terminal 178.

[0054] In some embodiments, the MDS100 includes a cable connector 184 configured to facilitate the transmission of various electrical signals between the sensor assembly 102 and the sensor electronic circuit 104 via the cable 170. In one embodiment, the cable connector 184 includes a positive sensor terminal 186 connected to a positive sensor signal 144P and a negative sensor terminal 188 connected to a negative sensor signal 144N. When the cable connector 184 is connected to the cable 170, the positive sensor terminal 186 is connected to the positive response wire 190 of the cable 170, and the negative sensor terminal 188 is connected to the negative response wire 192 of the cable 170. When the opposing ends of the cable 170 are connected to the sensor electronic circuit 104, the positive and negative response wires 190 and 192 may transmit the positive and negative sensor signals 144P and 144N from the driver circuit 176 to the sensor electronic circuit 104, such as a signal conditioner 160, for processing. Signals 144P and / or 144N may be used by the controller 116 to determine the position of the target magnet 108, as described above.

[0055] The cable connector 184 may include additional terminals for connecting conductive wires of cable 170 to the sensor assembly. For example, the cable connector 184 may include a waveguide terminal 194 connected to waveguide 106, which facilitates the transmission of current pulses 126 to waveguide 106 via waveguide wires 196 of cable 170. The cable connector 184 may also include a return terminal 198 which can be used to connect the end 124 of waveguide 106 to sensor electronics 104, such as an excitation generator circuit 120 or a circuit common voltage, via a return wire 199 of cable 170. Cable 170 may include additional conductive wires, and the cable connector 184 may include corresponding terminals for transmitting various signals between sensor assembly 102 and sensor electronics 104, such as an electrical common voltage or data signals.

[0056] The balanced line driver circuit 176 may take various forms. Figures 4 and 5 are schematic diagrams of the balanced line driver circuit 176 according to an embodiment of the present disclosure. In one embodiment, positive and negative response signal circuits 180 and 182 form a differential buffer that converts the high-impedance response signal 144 to low-impedance response signals 144P and 144N, providing various advantages such as eliminating common-mode noise and interference caused by external electric and magnetic fields acting on the connected cable 170.

[0057] The positive and negative response signal circuits 180 and 182 of the balanced line driver circuit 176 in Figure 4 generally comprise inverting operational amplifier differential circuits 200 and 202 (operational amplifiers), respectively. Circuit 200 is configured to transition the sensor signal 144 at the positive pickup terminal 177 from high impedance to low impedance positive sensor signal 144P.

[0058] In one embodiment, the circuit 200 includes an operational amplifier 204 connected to a power supply (VCC) (e.g., 3.3V) and an electrical common voltage 205. The negative input terminal 206 of the operational amplifier 204 is connected to the positive pickup terminal 177 of the sensing element 142, and the positive input terminal 208 is connected to the bias voltage (VB) (e.g., 1.65V). The operational amplifier 204 is generally configured to generate a positive sensor signal 144P by inverting the positive response signal 144 and possibly amplifying it with a desired gain. The positive sensor signal 144P is sent to the positive sensor terminal 186 of the connector 184.

[0059] Circuit 202 may be configured in a similar manner to circuit 200 and operates to transition the sensor signal 144 at the negative pickup terminal 178 from high impedance to a low impedance negative sensor signal 144N. Circuit 202 includes an operational amplifier 210 connected to the supply power (VCC) and the electrical common voltage 205. The negative input terminal 212 of the operational amplifier 210 is connected to the negative pickup terminal 178 of the sensing element 142, and the positive input terminal 214 is connected to the bias voltage (VB). The operational amplifier 210 is generally configured to generate the negative sensor signal 144N by inverting the negative response signal 144 and possibly amplifying it with a desired gain. The negative sensor signal 144N is sent to the negative sensor terminal 188 of the connector 184.

[0060] The inverting operational amplifier differential circuit 200 may be configured to provide a gain of approximately 1 to 10, such as approximately 3 to 10, by selecting resistors 220 and 222 (gain = -(R222 / R220)). Similarly, the inverting operational amplifier differential circuit 202 may be configured to provide a gain of approximately 1 to 10, such as approximately 3 to 10, by selecting resistors 224 and 226 (gain = -R226 / R224).

[0061] Circuit 200 may include a capacitor 228 for adjusting the low-pass filter frequency with respect to the positive response signal 144P. Resistor 230 may be used to adjust the output voltage of the positive response signal 144P sent to the positive sensor terminal 186.

[0062] Similarly, circuit 202 may include a capacitor 232 for adjusting the low-pass filter frequency with respect to the negative response signal 144N. Resistor 234 may be used to adjust the output voltage of the negative response signal 144N sent to the negative sensor terminal 188.

[0063] The bias voltage (VB) applied to the positive input terminals 208 and 214 of the operational amplifiers 204 and 210 may be realized by various techniques. In the exemplary balanced line driver circuit 176 of Figure 4, the bias voltage (VB) is provided by a bias voltage circuit 236, where the supply voltage (VCC) is supplied to a voltage divider formed by resistors 238 and 240, which may be maintained using a capacitor 242.

[0064] Capacitor 244 may be connected between the positive and negative pickup terminals 177 and 178. The combination of capacitor 244 and sensor coil 150 forms a band-pass filter (e.g., filter 147 in Figure 2), which is preferably tuned to pass frequencies (e.g., 100 kHz to 650 kHz) corresponding to an index of the magnetostrictive response in the sensor response signal 144, as described above.

[0065] The positive and negative response signal circuits 180 and 182 of the balanced line driver circuit 176 in Figure 5 generally comprise non-inverting operational amplifier differential circuits 250 and 252 (operational amplifiers), respectively. Circuit 250 is configured to transition the sensor signal 144 at the positive pickup terminal 177 from high impedance to low impedance positive sensor signal 144P.

[0066] In one embodiment, the circuit 250 includes an operational amplifier 254 connected to a power supply (VCC) and an electrical common voltage 205. The positive input terminal 256 of the operational amplifier 254 is connected to the positive pickup terminal 177 of the sensing element 142, via a resistor 257, and to the bias voltage (VB), while the negative input terminal 258 is connected to a resistor 270, and via a resistor 272, to the output of the operational amplifier 254.

[0067] Circuit 252 may be configured in a similar manner to circuit 250 and operates to transition the sensor signal 144 at the negative pickup terminal 178 from high impedance to a low impedance negative sensor signal 144N. Circuit 252 includes an operational amplifier 260 connected to the supply power (VCC) and the electrical common voltage 205. The positive input terminal 262 of the operational amplifier 260 is connected to the negative pickup terminal 178 of the sensing element 142 and to the bias voltage (VB) via a resistor 263, and the negative input terminal 264 is connected to a resistor 270 and to the output of the operational amplifier 260 via a resistor 274.

[0068] The non-inverting operational amplifier differential circuit 250 may be configured to generate a positive sensor signal 144P by amplifying the positive response signal 144 with a desired gain. The positive sensor signal 144P is sent to the positive sensor terminal 186 of the connector 184. In some embodiments, the gain is about 1 to 10, for example 3 to 10, and may be achieved by selecting resistors 270 and 272 (gain = 1 + 2 × R272 / R270).

[0069] Similarly, the non-inverting operational amplifier differential circuit 252 may be configured to generate a negative sensor signal 144N by amplifying the negative response signal 144 with a desired gain. The negative sensor signal 144N is sent to the negative sensor terminal 188 of the connector 184. In some embodiments, the gain is about 1 to 10, for example 3 to 10, and may be achieved by the selection of resistors 270 and 274 (gain = 1 + 2 × R274 / R270).

[0070] Resistor 280 may be used to adjust the output voltage of the positive response signal 144P sent to the positive sensor terminal 186, and resistor 284 may be used to adjust the output voltage of the negative response signal 144N sent to the negative sensor terminal 188.

[0071] The bias voltage (VB) applied to the positive input terminals 256 and 262 of the operational amplifiers 254 and 260 may be realized by various techniques. The bias voltage (VB) may be provided by the bias voltage circuit 236 described above, or by other suitable techniques.

[0072] Capacitor 286 may be connected between the positive and negative pickup terminals 177 and 178. The combination of capacitor 286 and sensor coil 150 forms a band-pass filter (e.g., filter 147 in Figure 2), which is preferably tuned to pass frequencies corresponding to the index of the magnetostrictive response in the sensor response signal 144 (e.g., 100 kHz to 650 kHz), as described above.

[0073] The function of converting the high-impedance sensor signal 144, which is performed by the exemplary positive and negative response signal circuits 180 and 182 in Figures 4 and 5, into a low-impedance sensor signal suitable for transmission over a long cable to the sensor electronic circuit 104, may be implemented using different circuits. For example, a suitable response signal circuit may be formed using transistors instead of operational amplifiers.

[0074] Embodiments of the sensor electronic circuit 104 include the function of receiving low-impedance sensor signals 144P and 144N from the sensor assembly 102 via the cable 170. In one embodiment, the signal conditioner 160 includes a receiver circuit 300 configured to receive a positive sensor signal 144P from a positive response wire 190, a negative sensor signal 144N from a negative sensor wire 192, and output a received sensor signal 148, as shown in Figure 2.

[0075] Figure 6 is a simplified schematic diagram of one embodiment of a receiver circuit 300 according to the present disclosure. In some embodiments, the receiver circuit 300 includes a transformer 302 that provides galvanic isolation between the sensor assembly 102 / cable 170 and the sensor electronic circuit 104. Based on the received response signals 144P and 144N, a current (sensor signal 144) is driven through the primary winding 304, which induces a corresponding current (received response signal 148) in the secondary winding 306.

[0076] In some embodiments, the supply voltage (VCC) is connected to the positive side of the secondary winding 306 via a resistor 308 and a capacitor 310. The capacitor 310 maintains a voltage corresponding to the voltage across the primary winding 304 and representing the received response signal 148 with respect to the electrical common voltage 205.

[0077] The turns ratio of transformer 302 may be selected to adjust the voltage of the response signal 148 within a desired range. Embodiments of the turns ratio of transformer 302 include 1:1, 1:2, and 1:3.

[0078] The receiver circuit 300 may also be formed using various active circuits, each having an input buffer with high impedance, low capacitance, and possibly some gain, to convert the sensor signal 144 into a response signal 148. If necessary, a suitable filter may be used to improve the signal-to-noise ratio of the response signal 148.

[0079] As described above, the response signal 148 may be processed by the controller 116 to identify an index of the magnetostrictive response and determine an estimated value 170 of the position 112 of the target magnet 108 with respect to the waveguide 106.

[0080] Figure 7 is a flowchart illustrating an exemplary method for operating an MDS 100 according to an embodiment of the present disclosure. In one embodiment, the MDS 100 includes a target magnet 108, a sensor assembly, and a sensor electronic circuit 104, formed according to one or more embodiments described herein. The sensor assembly includes a waveguide 106, a pickup 140, a signal conditioner 146 including a positive response signal circuit 180 and a negative response signal circuit 182, and a cable connector 184. The sensor electronic circuit 104 includes an excitation generator 120, a receiver circuit 300, and a controller 116.

[0081] In method 320, the cable 170 is connected to the signal conditioner 146 of the sensor assembly 102. For example, as shown in Figure 2, the positive response wire 190 of the cable 170 may be connected to the positive sensor terminal 186, the negative response wire 192 of the cable 170 may be connected to the negative sensor terminal 188, and / or the waveguide wire 196 of the cable 170 may be connected to the waveguide terminal 194.

[0082] In 322, the current pulse 126 generated using the excitation generator 120 is transmitted through the waveguide 106. For example, the current pulse 126 may be transmitted to the waveguide 106 via the waveguide wire 196 and the waveguide terminal 194. After passing through the waveguide 106, the current pulse 126 may be sent back via the return wire 122 as described above.

[0083] In 324, as shown in Figure 1, a sensor signal 144 is generated in response to the magnetostrictive response 134 in the waveguide 106 at position 112 of the target magnet 108, which responds to the current pulse 126. In some embodiments, the sensor signal 144 is generated with high impedance using the sensor element 142 of the pickup 140 at the positive pickup terminal 177 and the negative pickup terminal 178.

[0084] In 326, the high-impedance sensor signal 144 at the positive pickup terminal 177 is converted to a low-impedance positive sensor signal 144P using the positive response signal circuit 180, and the high-impedance sensor signal 144 at the negative pickup terminal 178 is converted to a low-impedance negative sensor signal 144N using the negative response signal circuit 182.

[0085] In method 328, the low-impedance positive and negative sensor signals 144P and 144N are sent to a receiver circuit 300, which generates a received sensor signal 148 based on the signals 144P and 144N. For example, the low-impedance positive sensor signal 144P may be transmitted to the receiver circuit 300 via a positive response wire 190, and the low-impedance negative sensor signal 144N may be transmitted to the receiver circuit 300 via a negative response wire 192. The receiver circuit 300 generates the received sensor signal 148 based on the signals 144P and 144N, for example, using a transformer 302 (Figure 6).

[0086] In step 330, the controller 116 is used to determine the estimated position 166 of the position 112 of the target magnet 108 relative to the waveguide 106, based on the received sensor signal 148.

[0087] While embodiments of this disclosure have been described with reference to preferred embodiments, those skilled in the art will recognize that the form and details may be modified without departing from the spirit and scope of this disclosure.

[0088] The functions described herein may be performed by a single controller or processor, multiple controllers or processors, or at least one controller or processor. Where, as used herein, one or more functions are described as being performed by one controller (e.g., a specific controller), one or more controllers, at least one controller, one processor (e.g., a specific processor), one or more processors, or at least one processor, embodiments include the execution of one or more functions by a single controller or processor, or by multiple controllers or processors, unless otherwise specified herein. Furthermore, where, as used herein, multiple functions are performed by at least one controller or processor, all of the functions may be performed by a single controller or processor, or some functions may be performed by one controller or one processor, and other functions may be performed by another controller or processor. Thus, the execution of one or more functions by at least one controller or processor does not require that all of the functions be performed by each of the multiple controllers or multiple processors, or by only one of the multiple controllers or multiple processors.

Claims

1. A magnetostrictive displacement sensor including a sensor assembly, The above sensor assembly comprises a waveguide, a pickup detection element, a signal conditioner, and a cable connector. The above-mentioned pickup detection element is configured to generate a high-impedance sensor response signal via the positive and negative pickup terminals in response to the magnetostrictive response in the waveguide corresponding to the target magnet. The above signal conditioner is, A positive response signal circuit configured to generate a low-impedance positive sensor signal based on the high-impedance sensor response signal at the positive pickup terminal, A negative response signal circuit configured to generate a low-impedance negative sensor signal based on the high-impedance sensor response signal at the negative pickup terminal, It includes a balanced line driver circuit, The above cable connector includes a positive sensor terminal connected to the positive sensor signal and a negative sensor terminal connected to the negative sensor signal. When a cable is connected to the above cable connector, the above balanced line driver circuit decouples the positive and negative pickup terminals from the capacitance of the above cable. Magnetostrictive displacement sensor.

2. The above positive and negative response signal circuits form a differential buffer. In one embodiment, the signal conditioner includes a bandpass filter configured to pass the frequency of the sensor response signal in the range of approximately 100 kHz to 650 kHz through the balanced line driver circuit. The magnetostrictive displacement sensor according to claim 1.

3. The above-described positive response signal circuit comprises a first inverting operational amplifier having a first negative input terminal connected to the positive pickup terminal and a first positive input terminal connected to a reference voltage, and the first inverting operational amplifier is configured to amplify the high-impedance sensor response signal with a first gain to generate the positive sensor signal. The negative response signal circuit includes a second inverting operational amplifier having a second negative input terminal connected to the negative pickup terminal and a second positive input terminal connected to a reference voltage, and the second inverting operational amplifier is configured to amplify the high impedance sensor response signal with a first gain to generate the negative sensor signal. The magnetostrictive displacement sensor according to claim 1 or 2.

4. The above-described positive response signal circuit comprises a first non-inverting operational amplifier having a first positive input terminal connected to the positive pickup terminal and a first negative input terminal, wherein the first non-inverting operational amplifier is configured to amplify the high-impedance sensor response signal with a first gain to generate the positive sensor signal, and to feed back the positive sensor signal to the first negative input terminal. The negative response signal circuit described above comprises a second non-inverting operational amplifier having a second positive input terminal connected to the negative pickup terminal and a second negative input terminal, wherein the second non-inverting operational amplifier is configured to amplify the high impedance sensor response signal with a first gain to generate the negative sensor signal, and to feed the negative sensor signal back to the second negative input terminal. The magnetostrictive displacement sensor according to claim 1 or 2.

5. The first gain described above is set to approximately 3 to 10. The magnetostrictive displacement sensor according to claim 3 or 4.

6. The above magnetostrictive displacement sensor includes a cable and a sensor electronic circuit. The above cable is attached to the above cable connector, and the cable includes a positive response wire connected to the positive sensor terminal, a negative response wire connected to the negative sensor terminal, and a waveguide wire connected to the waveguide terminal of the cable connector, which is connected to the waveguide. In one embodiment, the length of the cable is greater than approximately 3 meters. The above-mentioned sensor electronic circuit is An excitation generator configured to generate current pulses transmitted to the waveguide via 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 to output a received sensor signal, The system includes a controller configured to generate an estimated position of the target magnet with respect to the waveguide based on the received sensor signal, In one embodiment, the receiver circuit includes a transformer. A magnetostrictive displacement sensor according to one of claims 1 to 5.

7. A magnetostrictive displacement sensor comprising a target magnet, a sensor assembly, a cable, and a sensor electronic circuit, The above sensor assembly comprises a waveguide, a pickup detection element, a signal conditioner, and a cable connector. The pickup detection element described above is configured to generate a high-impedance sensor response signal via a positive pickup terminal and a negative pickup terminal in response to the magnetostrictive response in the waveguide corresponding to the target magnet. The above signal conditioner is, A positive response signal circuit configured to generate a low-impedance positive response signal based on the high-impedance sensor response signal at the above positive pickup terminal, A negative response signal circuit configured to generate a low-impedance negative sensor signal based on the high-impedance sensor response signal at the negative pickup terminal, It includes a balanced line driver circuit, The above cable connector includes a positive sensor terminal connected to the positive sensor signal, a negative sensor terminal connected to the negative sensor signal, and a waveguide terminal connected to the waveguide. The above cable is attached to the above cable connector, and the above cable includes a positive response wire connected to the positive sensor terminal, a negative response wire connected to the negative sensor terminal, and a waveguide wire connected to the waveguide terminal. The above-mentioned sensor electronic circuit is An excitation generator configured to generate current pulses transmitted to the waveguide via 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 to output a received sensor signal, The system includes a controller configured to generate an estimated position of the target magnet with respect to the waveguide based on the received sensor signal. Magnetostrictive displacement sensor.

8. The above positive and negative response signal circuits form a differential buffer. The magnetostrictive displacement sensor according to claim 7.

9. The above-described positive response signal circuit comprises a first inverting operational amplifier having a first negative input terminal connected to the positive pickup terminal and a first positive input terminal connected to a reference voltage, and the first inverting operational amplifier is configured to amplify the high-impedance sensor response signal with a predetermined gain to generate the positive sensor signal. The negative response signal circuit includes a second inverting operational amplifier having a second negative input terminal connected to the negative pickup terminal and a second positive input terminal connected to a reference voltage, and is configured to amplify the high impedance sensor response signal with the above gain to generate the negative sensor signal. The magnetostrictive displacement sensor according to claim 7 or 8.

10. The above-described positive response signal circuit comprises a first non-inverting operational amplifier having a first positive input terminal connected to the positive pickup terminal and a first negative input terminal, wherein the first non-inverting operational amplifier is configured to amplify the high-impedance sensor response signal with a predetermined gain to generate the positive sensor signal, and to feed back the positive sensor signal to the first negative input terminal. The negative response signal circuit includes a second non-inverting operational amplifier having a second positive input terminal connected to the negative pickup terminal and a second negative input terminal, wherein the second non-inverting operational amplifier is configured to amplify the high impedance sensor response signal with the above gain to generate the negative sensor signal, and to feed the negative sensor signal back to the second negative input terminal. The magnetostrictive displacement sensor according to claim 7 or 8.

11. The above gain is set to approximately 3 to 10. The magnetostrictive displacement sensor according to claim 9 or 10.

12. The above signal conditioner includes a bandpass filter configured to pass the frequency of the sensor response signal in the range of approximately 100 kHz to 650 kHz through the above balanced line driver circuit. The magnetostrictive displacement sensor according to claim 7 or 8.

13. The above receiver circuit includes a transformer. The magnetostrictive displacement sensor according to claim 7 or 12.

14. The length of the above cable is greater than approximately 3 meters. The magnetostrictive displacement sensor according to claim 7 or 12.

15. A method for operating a magnetostrictive displacement sensor, The above magnetostrictive displacement sensor comprises a target magnet, a sensor assembly, and a sensor electronic circuit. The above sensor assembly comprises a waveguide, a pickup detection element, a signal conditioner, and a cable connector. The above signal conditioner includes a balanced line driver circuit that includes a positive response signal circuit and a negative response signal circuit. The above cable connector includes a positive sensor terminal, a negative sensor terminal, and a waveguide terminal. The above sensor electronic circuit comprises an excitation generator, a receiver circuit, and a controller. The above method, Connect the positive response wire of the cable to the positive sensor terminal, connect the negative response wire of the cable to the negative sensor terminal, and connect the waveguide wire of the cable to the waveguide terminal. The current pulse generated using the above excitation generator is transmitted to the waveguide via the waveguide wire and the waveguide terminal, To generate a magnetostrictive response in the waveguide at the position of the target magnet in response to a current pulse in the waveguide, A high-impedance sensor response signal for the magnetostrictive response is generated via the positive and negative pickup terminals of the above-mentioned pickup detection element. Using the above positive response signal circuit, the high-impedance sensor response signal at the positive pickup terminal is converted into a low-impedance positive sensor signal. Using the above negative response signal circuit, the high-impedance negative sensor signal is converted to a low-impedance negative sensor signal, The low-impedance positive sensor signal is transmitted to the receiver circuit via the positive response wire, and the low-impedance negative sensor signal is transmitted to the receiver circuit via the negative response wire. Using the above receiver circuit, a received sensor signal is generated based on the above low-impedance positive sensor signal and the above low-impedance negative sensor signal. This includes using the above controller to determine the estimated position of the target magnet relative to the waveguide based on the received sensor signal, method.

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