Non-contact valve position detection structure and valve positioner

Abstract

The utility model discloses a kind of non-contact valve position detection structures of not easy failure, high measurement accuracy, can reduce external magnetic field interference, including fixed in the shell of valve positioner and for measuring magnetic field direction angle magnetic induction angle sensor, with the feedback shaft assembly of non-contact cooperation of magnetic induction angle sensor, magnetic induction angle sensor is electrically connected with the mainboard of valve positioner, feedback shaft assembly includes fixed in the mounting support seat of valve positioner shell outer surface, rotates through the feedback shaft of mounting support seat, magnet, feedback shaft is limited cooperation along its axial direction with mounting support seat, feedback shaft includes the first end adjacent to magnetic induction angle sensor and the second end away from magnetic induction angle sensor, magnet is fixed in the first end and with magnetic induction angle sensor induction cooperation, second end is fixedly connected with the valve stem of valve and follows valve stem synchronous rotation. Also disclosed is a valve positioner comprising the above non-contact valve position detection structure.

Description

Technical Field

[0001] This utility model relates to the field of valve positioner technology, and in particular to a non-contact valve position detection structure and valve positioner. Background Technology

[0002] A valve positioner is an industrial field instrument used for controlling pneumatic valves. It typically consists of a housing, a control electronics module, a valve position sensor, and an electrical conversion module. The valve positioner receives and measures control signals from a higher-level control system, detects the actual valve position using the valve position sensor, compares the two, and then adjusts the air pressure output to the pneumatic actuator. Ultimately, the pneumatic actuator drives the valve to the target valve position represented by the control signal, thus achieving valve control. Based on different valve position measurement technologies, valve positioners are mainly divided into potentiometer-based valve positioners and linear Hall effect displacement sensor-based valve positioners. The former uses a potentiometer, an external feedback connector for mechanical transmission with the valve stem, an internal feedback shaft, and gears to achieve valve position measurement. The latter measures the Hall voltage signal from a linear Hall effect sensor to obtain the magnetic field magnitude and displacement change, achieving non-contact measurement of valve displacement.

[0003] However, for potentiometer-based valve positioners, which are contact-type valve position sensors, the internal brushes and resistive elements may experience poor contact or even resistor failure due to wear at the contact points or surfaces after long-term reciprocating motion. For bushing-type potentiometers, due to sliding friction between the shaft and bushing, the bushing will wear significantly after prolonged use, causing a sharp increase in sliding friction between the shaft and bushing, potentially leading to shaft jamming and malfunction, making it difficult to effectively measure valve position. Furthermore, since the feedback shaft and potentiometer shaft are driven by gears, and gears inherently have transmission backlash that increases with use, this backlash leads to significant transmission hysteresis, reducing valve position measurement accuracy.

[0004] For valve positioners based on linear Hall displacement sensors, although they can avoid valve position measurement failure caused by potentiometer wear and jamming, as well as backlash and accuracy reduction caused by gear transmission clearance, the linear Hall displacement sensor directly measures the magnetic field strength. When there is a large electromagnetic field interference in the surrounding area, it will have an adverse effect on the measurement. Therefore, magnetic shielding measures must be taken for the magnet and the linear Hall displacement sensor, which further increases the design difficulty and cost. Utility Model Content

[0005] Therefore, it is necessary to address the above-mentioned shortcomings by providing a non-contact valve position detection structure and valve positioner that is not prone to failure, has high measurement accuracy, and can reduce external magnetic field interference.

[0006] A non-contact valve position detection structure includes a magnetic induction angle sensor fixed inside the housing of a valve positioner for measuring the direction angle of a magnetic field, and a feedback shaft assembly that non-contactly engages with the magnetic induction angle sensor. The magnetic induction angle sensor is electrically connected to the main board of the valve positioner. The feedback shaft assembly includes a mounting support fixed to the outer surface of the valve positioner housing, a feedback shaft that rotatably passes through the mounting support, and a magnet. The feedback shaft is axially engaged with the mounting support and includes a first end adjacent to the magnetic induction angle sensor and a second end away from the magnetic induction angle sensor. The magnet is fixed to the first end and engages with the magnetic induction angle sensor. The second end is fixedly connected to the valve stem and rotates synchronously with the valve stem.

[0007] In one embodiment, the feedback shaft assembly further includes a bushing that is inserted into a mounting support and rotatably engages with the feedback shaft.

[0008] In one embodiment, the mounting support includes a flange fixed to the outer surface of the housing and a limiting cylinder fixedly connected to the flange and extending axially along the feedback shaft. The inner cavity of the limiting cylinder communicates with the central through hole of the flange. The upper inner wall of the limiting cylinder protrudes to form a mounting ring. The mounting ring and the inner wall of the limiting cylinder above it form a first mounting groove. The bushing includes a sleeve inserted into the inner cavity of the limiting cylinder and a limiting ring fixed to the top of the sleeve and located in the first mounting groove. The central opening of the limiting ring communicates with the inner cavity of the sleeve and the central through hole of the flange to form a feedback shaft through channel.

[0009] In one embodiment, the feedback shaft includes a shaft body, a shoulder fixed to the top of the shaft body, and a cap fixed to the top of the shoulder. The width or diameter of the shaft body, shoulder, and cap increases sequentially. The shaft body passes through the feedback shaft connection channel and extends from below the flange. The lower part of the shaft body is provided with a first connecting groove and a second connecting groove located below the flange. The shoulder and cap are located above the limiting ring. The upper surface of the cap is provided with a non-circular slot for receiving the magnet. The outer contour shape of the magnet is adapted to the inner contour shape of the non-circular slot.

[0010] In one embodiment, the feedback shaft assembly further includes a first sealing ring fitted in a first connecting groove and limited to the inner wall of a limiting cylinder, a retaining ring fitted in a second connecting groove, a first washer fitted on the shaft body and located between the first sealing ring and the retaining ring, a feedback shaft indicator fitted on the shaft body and located below the retaining ring, and a second washer, a third washer, and a fourth washer sequentially fitted on the shaft shoulder from bottom to top. The upper surface of the first washer abuts against the lower surface of the flange, the lower surface of the first washer abuts against the retaining ring, the feedback shaft indicator is limited to the shaft body along the radial direction of the shaft body, the lower surface of the second washer abuts against the upper surface of the mounting ring, and the upper surface of the fourth washer abuts against the lower surface of the shaft cap.

[0011] In one embodiment, the magnet is a permanent magnet.

[0012] This utility model also discloses a valve positioner, which includes the above-mentioned non-contact valve position detection structure, as well as a housing and a main board and an electrical conversion module housed in the inner cavity of the housing. The electrical conversion module is electrically connected to the main board, the magnetic induction angle sensor is fixed in the inner cavity of the housing, and the mounting support is fixed on the outer bottom surface of the housing.

[0013] In one embodiment, the housing includes a top cover and a bottom cover located below the top cover and fixedly connected to the top cover. The bottom surface of the bottom cover is provided with a plurality of mounting studs for fixing the motherboard and a feedback shaft located between the plurality of mounting studs. The feedback shaft is spaced apart from the mounting studs and is independently provided, or the feedback shaft is integrally formed with at least a portion of the mounting studs. The feedback shaft platform has a mounting hole extending axially along the feedback shaft and penetrating the upper surface of the feedback shaft platform and the lower surface of the bottom shell. A support plate is provided in the mounting hole. The support plate separates the mounting hole to form a second mounting groove for embedding a magnetic induction angle sensor and a slot located below the second mounting groove. The lower surface of the bottom shell has a limiting groove communicating with the slot opening and used to fix the mounting support. At least a part of the mounting support and the feedback shaft are inserted into the slot.

[0014] In one embodiment, the support plate separates the mounting holes to form a second, non-communicating mounting groove and slot; or the support plate is annular in structure, with a portion of the magnet or a portion of the magnet and feedback shaft inserted into the annular space of the support plate.

[0015] In one embodiment, the motherboard includes a housing, a control circuit board housed within the housing, a display screen and buttons mounted on the housing and electrically connected to the control circuit board, a grounding plate soldered to the control circuit board and connected to the internal protective ground of the control circuit board, and mounting screws penetrating the grounding plate and the housing and fixedly connected to the housing.

[0016] The non-contact valve position detection structure and valve positioner of this utility model utilize a magnetic induction angle sensor in synergy with a magnet at the top of the feedback shaft. It detects the valve position by detecting the angle of change in the magnetic field direction. As long as the magnetic induction angle sensor is in a saturated magnetic field, the measurement accuracy is unaffected by external magnetic field interference, significantly improving its resistance to external magnetic field interference. The non-contact synergy between the magnet and the magnetic induction angle sensor, compared to traditional potentiometer-based valve position measurement technology, eliminates the wear caused by repeated contact between brushes and resistors, and avoids the hysteresis caused by transmission clearance in the feedback gear assembly. This makes the valve position detection structure less prone to failure, improving both its service life and reliability, while also enhancing valve position measurement accuracy. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the valve positioner in one embodiment of the present invention; Figure 2 for Figure 1 A bottom view of the valve positioner in the illustrated embodiment; Figure 3 for Figure 1 The exploded structural diagram of the valve positioner in the illustrated embodiment is shown. Figure 4 for Figure 3 A magnified schematic diagram of part A in the middle section; Figure 5 for Figure 3 A partially enlarged structural diagram of section B; Figure 6 for Figure 1 A schematic diagram of the feedback shaft assembly in the embodiment shown; Figure 7 for Figure 1 An exploded view of the feedback shaft assembly in the illustrated embodiment; Figure 8 This is a schematic diagram of the valve positioner in another embodiment of the present invention; Figure 9 for Figure 8 A bottom view of the valve positioner in the illustrated embodiment; Figure 10 for Figure 8 The exploded structural diagram of the valve positioner in the illustrated embodiment is shown. Figure 11 for Figure 10 A magnified schematic diagram of part C in the middle; Figure 12 for Figure 10 A magnified schematic diagram of part D in the middle section. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0019] This utility model discloses a non-contact valve position detection structure that is not prone to failure, has high measurement accuracy, and reduces interference from external magnetic fields. This non-contact valve position detection structure is installed on a valve positioner to detect the valve position. This allows the electrical conversion module within the valve positioner to drive the external valve, providing feedback to adjust the valve position and thus control the valve. For details, please refer to... Figure 1-4 as well as Figure 6-7 The non-contact valve position detection structure of this embodiment includes a magnetic induction angle sensor 200 fixed inside the housing 100 of the valve positioner 10 for measuring the direction angle of the magnetic field, and a feedback shaft assembly 300 that non-contactly cooperates with the magnetic induction angle sensor 200. In other words, in this embodiment, the magnetic induction angle sensor 200 and the feedback shaft assembly 300 engage in a non-contact sensing manner, thereby acquiring valve opening information through the magnetic induction angle sensor 200. The magnetic induction angle sensor 200 is electrically connected to the main board of the valve positioner 10 to send the acquired valve opening information to the main board of the valve positioner 10, so that the main board can further control the operation of the electrical conversion module. The feedback shaft assembly 300 includes a mounting support 310 fixed to the outer surface of the valve positioner 10 housing 100, a feedback shaft 320 rotatably passing through the mounting support 310, and a magnet 330. The feedback shaft 320 is axially positioned and engaged with the mounting support 310. Correspondingly, the mounting support 310 is also fixedly connected to the outer surface of the valve positioner 10 housing along the axial direction of the feedback shaft 320, thereby limiting the feedback shaft assembly 300 along the axial direction of the feedback shaft 320, preventing the feedback shaft 320 from wobbling relative to the mounting support 310 during rotation, and preventing the mounting support 310 from falling off the housing 100. The feedback shaft 320 includes a first end adjacent to the magnetic induction angle sensor 200 and a second end away from the magnetic induction angle sensor 200. The magnet 330 is fixed to the first end and engages with the magnetic induction angle sensor 200, and the second end is fixedly connected to the valve stem and rotates synchronously with the valve stem.

[0020] A magnetic induction angle sensor is a sensor that measures rotation angle by detecting changes in a magnetic field. When a magnetic induction angle sensor is subjected to a magnetic field, its resistance changes depending on the direction and strength of the magnetic field. When the magnetic field strength is strong enough to saturate the sensor, the resistance change depends only on the direction of the magnetic field. At this point, by measuring the change in resistance, the angle of change in the magnetic field direction can be determined. In this embodiment, the magnetic induction angle sensor 200 uses any commercially available model that meets the requirements of a valve positioner. Its working principle and structure are common knowledge in the industry and will not be elaborated upon here.

[0021] In this embodiment, the second end of the feedback shaft 320 is fixedly connected to the valve stem by a pin. When the valve is activated, the valve stem drives the feedback shaft 320 to rotate along its axis via the pin, thereby generating an angular displacement proportional to the valve opening. Similarly, the magnet 330 fixed to the first end of the feedback shaft 320 rotates synchronously with the feedback shaft 320. During the rotation of the magnet 330 relative to the magnetic induction angle sensor 200, the direction of the magnetic field generated at the position of the magnetic induction angle sensor 200 changes continuously. The two mutually perpendicular Wheatstone bridges inside the magnetic induction angle sensor 200 output two analog voltage signals to the main board of the valve positioner 10 in real time, so that the main board can process the two analog voltage signals to obtain the absolute angular position of the magnet 330, that is, to obtain the valve opening information.

[0022] In one embodiment, the feedback shaft assembly 300 further includes a bushing 340 inserted into the mounting support 310 and rotatably engaged with the feedback shaft 320. The bushing 340 is used to support the feedback shaft 320 so as to achieve stable installation of the feedback shaft 320 in the mounting support 310. Furthermore, the mounting support 310 includes a flange 311 fixed to the outer surface of the housing 100, and a limiting cylinder 312 fixedly connected to the flange 311 and extending axially along the feedback shaft 320. The inner cavity of the limiting cylinder 312 communicates with the central through hole of the flange 311. The upper inner wall of the limiting cylinder 312 protrudes to form a mounting ring 313. The mounting ring 313 and the inner wall of the limiting cylinder 312 above it form a first mounting groove 314. The bushing 340 includes a sleeve 341 inserted into the inner cavity of the limiting cylinder 312, and a limiting ring 342 fixed to the top of the sleeve 341 and located in the first mounting groove 314. The central opening of the limiting ring 342 communicates with the inner cavity of the sleeve 341 and the central through hole of the flange 311 to form a feedback shaft through channel. This can be understood as follows: the mounting support 310 has an inverted T-shaped structure, and the flange 311 is fixed to the outer surface of the housing 100 with screws to achieve the installation of the mounting support 310 on the housing 100. The mounting ring 313 is used to cooperate with the limiting ring 342 of the bushing 340 to support the bushing 340 and limit the installation position of the bushing 340 on the mounting support 310. In this embodiment, the flange 311, the limiting ring 312, and the mounting ring 313 are integrally formed to improve the overall structural stability of the mounting support 310; the sleeve 341 and the limiting ring 342 are integrally formed to improve the structural stability of the bushing 340.

[0023] The feedback shaft 320 includes a shaft body 321, a shoulder 322 fixed to the top of the shaft body 321, and a cap 323 fixed to the top of the shoulder 322. The width or diameter of the shaft body 321, shoulder 322, and cap 323 increases sequentially, meaning the feedback shaft 320 is a stepped shaft. The shaft body 321 passes through the feedback shaft connection channel and extends from below the flange 311. The portion of the shaft body 321 extending below the flange 311 provides a connection point for the valve stem. The lower part of the shaft body 321 is provided with a first connecting groove 324 and a second connecting groove 325 located below the flange 311. The shoulder 322 and cap 323 are located above the limiting ring 342. In other words, the width or diameter of the shoulder 322 is greater than the width or diameter of the space inside the limiting ring 342, thereby restricting the shoulder 322 and cap 323 above the limiting ring 342 to position the feedback shaft 320.

[0024] The upper surface of the shaft cap 323 is provided with a non-circular groove 326 for accommodating the magnet 330. The outer contour shape of the magnet 330 is adapted to the inner contour shape of the non-circular groove 326. That is to say, the cross-section of the magnet 330 is also a non-circular structure. In this way, by mutually restricting the side of the magnet 330 ring and the inner surface of the non-circular groove 326, the magnet 330 can be prevented from rotating relative to the feedback shaft 320 during the rotation of the feedback shaft 320, ensuring the synchronous rotation of the magnet 330 and the feedback shaft 320, so that the angle information of the magnet 330 collected by the magnetic induction angle sensor 200 can truly reflect the opening of the valve. In this embodiment, the magnet 330 is embedded in the non-circular slot 326 and tightly fitted or bonded to the inner wall of the non-circular slot 326. An arc-shaped groove penetrating the upper surface of the shaft cap 323 is provided at the corner of the inner surface of the non-circular slot 326. During the process of embedding the magnet 330 into the non-circular slot 326, air between the bottom of the magnet 330 and the inner surface of the non-circular slot 326 can be discharged through the arc-shaped groove, thus avoiding resistance to the embedding of the magnet 330 by the air column between the magnet 330 and the inner surface of the non-circular slot 326, thereby reducing the installation difficulty of the magnet 330. The magnet 330 is a permanent magnet, and more particularly, it is a permanent magnet. Preferably, in this embodiment, the magnet 330 is a radially magnetized permanent magnet.

[0025] To improve the stability of the feedback shaft 320 installation, in one embodiment, the feedback shaft assembly 300 further includes a first sealing ring 350 embedded in the first connecting groove 324 and limited to the inner wall of the limiting cylinder 312, a retaining ring 360 embedded in the second connecting groove 325, a first washer 370 sleeved on the shaft body 321 and located between the first sealing ring 350 and the retaining ring 360, and a feedback shaft indicator 371 sleeved on the shaft body 321 and located below the retaining ring 360, from bottom to top. The second washer 380, the third washer 381, and the fourth washer 382 are sequentially fitted onto the shoulder 322. The upper surface of the first washer 370 abuts against the lower surface of the flange 311, and the lower surface of the first washer 370 abuts against the retaining ring 360. The feedback shaft indicator 371 is radially positioned against the shaft body 321. The lower surface of the second washer 380 abuts against the upper surface of the mounting ring 313, and the upper surface of the fourth washer 382 abuts against the lower surface of the shaft cap 323. Thus, through the engagement of the first sealing ring 350 with the inner wall of the feedback shaft 320 and the limiting cylinder 312, external oil contaminants are prevented from entering the bushing 340 through the insertion point between the feedback shaft 320 and the bushing 340, thereby preventing contamination of the magnet 330 on the feedback shaft 320. The engagement of the retaining ring 360 and the first washer 370 establishes a limiting connection between the bottom of the feedback shaft 320 and the mounting support 310, preventing the feedback shaft 320 from wobbling relative to the mounting support 310 along its axial direction. The second washer 380, the third washer 381, and the fourth washer 382 work together to provide axial elastic preload on the feedback shaft 320 and the bushing 340, compensating for dimensional tolerances and vibration loosening. Thus, the top of the feedback shaft 320 acts on the second washer 380, the third washer 381, and the fourth washer 382 through the shaft cap 323, indirectly acting on the bushing 340. The top of the bushing 340 further presses against the mounting support 310, while the bottom of the feedback shaft 320, through the engagement of the retaining ring 360 and the first washer 370, engages with the bottom of the mounting support 310, thereby achieving axial positioning of the feedback shaft 320 and preventing it from wobbling relative to the mounting support 310 during rotation. Preferably, in this embodiment, the retaining ring 360 is a C-shaped retaining ring with an opening, the first washer 370 is a friction-reducing washer, the second washer 380 and the fourth washer 382 are annular washers of equal thickness, and the third washer 381 is a saddle-shaped elastic washer or a corrugated washer. Additionally, the feedback shaft indicator 371 is located at the bottom of the housing 100 and is used to indicate the rotation of the feedback shaft 320. Specifically, one side of the feedback shaft indicator 371 forms a cone-shaped indicator portion, and a non-circular hole is provided on the feedback shaft indicator 371. The lower part of the shaft body 321 has a non-circular portion that matches the non-circular hole, so that while the feedback shaft indicator 371 is fitted onto the lower part of the shaft body 321 through the non-circular hole, the feedback shaft indicator 371 is prevented from rotating relative to the shaft body 321, thereby correctly indicating the rotation of the feedback shaft 320 through the feedback shaft indicator 371.

[0026] Please combine further Figure 1-7This utility model also discloses a valve positioner 10, which includes the aforementioned non-contact valve position detection structure. The valve positioner 10 also includes a housing 100, a main board 400 housed within the housing 100, and an electrical conversion module 500. The electrical conversion module 500 is electrically connected to the main board 400. A magnetic induction angle sensor 200 is fixed within the housing 100, and a mounting support 310 is fixed to the outer bottom surface of the housing 100. In this embodiment, the housing 100 is provided with a channel for providing a working air path to the electrical conversion module 500 to adjust the opening of the external valve. The main board 400 is the core electronic component of the valve positioner 10, used for power supply, measurement of signals other than valve position, control logic processing, and button and display operations. Furthermore, the housing 100 includes a top cover 110 and a bottom cover 120 located below and fixedly connected to the top cover 110. The inner bottom surface of the bottom cover 120 is provided with a plurality of mounting studs 130 for fixing the main board 400, and a feedback shaft platform 140 located between the mounting studs 130. The main board 400 is fixed to each mounting stud 130 by bolts or screws. The bottom cover 120 and the top cover 110 are connected by screws, and a sealing ring is provided at the connection point. Together, they encapsulate the main board 400, the electrical conversion module 500, and the magnetic induction angle sensor 200, providing effective IP protection and mounting fixation for the internal modules. The feedback shaft platform 140 has a mounting hole extending axially along the feedback shaft 320 and penetrating the upper surface of the feedback shaft platform 140 and the lower surface of the bottom shell 120. A support plate 141 is provided in the mounting hole, and the support plate 141 divides the mounting hole to form a second mounting groove 142 for embedding the magnetic induction angle sensor 200 and a slot 143 located below the second mounting groove 142. The lower surface of the bottom shell 120 has a limiting groove 121 that communicates with the opening of the slot 143 and is used to fix the mounting support 310. At least a part of the mounting support 310 and the feedback shaft 320 are inserted into the slot 143. Specifically, the flange 311 of the mounting support 310 is embedded in the limiting groove 121 and connected to the limiting groove 121 with screws, and the limiting sleeve 312 of the mounting support 310 is inserted into the slot 143. Furthermore, a second sealing ring 122 is fitted at the bottom of the limiting cylinder 312 where it meets the flange 311. This second sealing ring 122 seals the gap between the outer wall of the bottom end of the limiting cylinder 312 and the slot 143 to prevent oil or water from entering the slot 143. In this way, components such as the limiting cylinder 312, the bushing 340, and the magnet 330 can be encapsulated within the slot 143, protecting these components from shaking or damage under external impact. The inner contour shape of the second mounting groove 142 conforms to the outer contour shape of the lower part of the magnetic induction angle sensor 200 to achieve positioning of the magnetic induction angle sensor 200.To improve the stability of the magnetic induction angle sensor 200 during installation, the magnetic induction angle sensor 200 is also bonded to the inner wall of the second mounting groove 142 to prevent it from falling off the feedback shaft platform 140 during the movement or transportation of the valve positioner 10. Additionally, in this embodiment, the magnetic induction angle sensor 200 is fixed to the support plate 141 via a non-contact valve position sensor plate.

[0027] It should be noted that in this embodiment, the feedback shaft platform 140 and the mounting stud 130 are spaced apart and independently arranged, and the valve positioner is an intrinsically safe valve positioner (e.g., Figure 1-7 (As shown). Please refer to... Figure 8-12 In another embodiment, the feedback shaft 140 is integrally formed with at least a portion of the mounting studs 130 to improve the stability of the motherboard 400 installation, and the valve positioner is an explosion-proof valve positioner.

[0028] Furthermore, depending on whether the housing 100 is connected to the outside, the valve positioner 10 is further divided into through-type and non-through-type structures. Specifically, in one embodiment, the support plate 141 has an annular structure, and a portion of the magnet 330 or a portion of the magnet 330 and the feedback shaft 320 are inserted into the annular space of the support plate 141. In this case, the valve positioner 10 adopts a through-type feedback shaft, that is, the feedback shaft 320 used for mechanical transmission and mounting of the magnet 330 passes through the support plate 141, so that the magnet 330 can be as close as possible to the magnetic induction angle sensor 200 to ensure reliable measurement. In this case, the magnetic induction angle sensor 200 still cooperates with the magnet 330 in a non-contact manner to measure the valve position. At this time, due to the annular structure of the support plate 141 (with a hole in the middle of the support plate 141), the integrity of the housing is compromised, and the protective performance is reduced. Therefore, a sealing ring needs to be added at the junction of the feedback shaft 320 and the hole in the middle of the support plate 141 to achieve waterproof and dustproof protection. Furthermore, considering that the operating temperature range of field instruments is generally quite wide (e.g., -40~+80℃), sealing rings capable of operating within a wide temperature range are required. For applications with strong corrosion, sealing rings made of corrosion-resistant materials are also necessary. Alternatively, the mounting structure formed by the feedback shaft platform 140 and the support plate 141 can be modified into a mounting bracket fixed inside the base housing 120. The magnetic induction angle sensor 200 can be fixed on the mounting bracket, and corresponding holes can be made in the base housing 120 to provide a passage for the feedback shaft assembly 300. Sealing rings can be installed at the holes to achieve the protective design of the feedback shaft 320.

[0029] In another embodiment, the support plate 141 separates the mounting holes to form a second, non-communicating mounting groove 142 and slot 143. In this case, the valve positioner 10 adopts a non-through, partitioned structural design, meaning that the feedback shaft 320 does not pass through the housing 100 directly to the internal cavity of the valve positioner 10. Instead, an inwardly raised boss (i.e., feedback shaft platform 140) is designed at the bottom of the housing 100 to reserve mounting space for the feedback shaft 320 and the bushing 340. Then, a magnet 330 is installed on the top of the feedback shaft 320. In this way, the feedback shaft 320 and the magnet 330 are isolated from the internal cavity of the valve positioner 10 by the housing 100, which greatly improves the overall protection performance. This protects the internal electronic components of the valve positioner 10 from external influences, eliminates the need for complex protective designs for the feedback shaft 320 and the magnet 330, and does not compromise the protective performance of the housing 100, thereby improving product reliability and reducing the cost and manufacturing difficulty of the valve positioner 10.

[0030] The motherboard 400 includes a housing 410, a control circuit board 420 housed within the housing 410, a display screen 430 mounted on the housing 410 and electrically connected to the control circuit board 420, buttons 440, a grounding plate 450 soldered to the control circuit board 420 and connected to the internal protective ground of the control circuit board 420, and mounting screws 460 passing through the grounding plate 450 and the housing 410 and fixedly connected to the casing 100. Preferably, the grounding plate 450 is made of copper sheet by stamping. The grounding plate 450 includes a body 451, two pins 452 disposed on both sides of the body 451, and a support plate 453 fixedly connected to the body 451 and protruding from the control circuit board 420. The support plate 453 has a connection hole 454. The pins 452 are soldered to the control circuit board 420 and electrically connected to the internal protective ground of the control circuit board 420. The side edge of the grounding plate 450 abuts against the housing 410. The mounting screw 460 passes through the housing 410 and the connection hole 454 and is inserted into the mounting stud 130, or the mounting screw 460 passes through the housing 410 and the connection hole 454 and is inserted into the screw hole on the feedback shaft platform 140, thereby fixing the control circuit board 420 on the bottom shell 120, realizing the internal grounding of the electronic module inside the valve positioner 10, and realizing the fixed installation of the electronic module. In this embodiment, a concealed grounding plate with internal grounding is used, which differs from the common grounding method of making a special ground wire or circuit board pads. It adopts a uniquely designed grounding plate 450 and is combined with the electronic module's own mounting structure. This avoids the problems of poor contact between grounding wires and terminals in common grounding methods, as well as the inability to effectively ground through screws and pads when the circuit board surface is coated with conformal coating or uses potting technology. In this way, without increasing material costs, it can also simplify manufacturing difficulty and reduce processing time, thereby reducing costs and improving grounding reliability.

[0031] The non-contact valve position detection structure and valve positioner 10 of this utility model utilize the inductive engagement between a magnetic induction angle sensor 200 and a magnet 330 at the top of the feedback shaft 320. It detects the valve position by detecting the angle of change in the magnetic field direction. As long as the magnetic induction angle sensor 200 is in a saturated magnetic field, the measurement accuracy is guaranteed to be unaffected by external magnetic field interference, significantly improving its resistance to external magnetic field interference. The non-contact engagement between the magnet 330 and the magnetic induction angle sensor 200, compared to traditional potentiometer-type valve position measurement technology, eliminates the wear caused by repeated contact between brushes and resistors, and avoids the hysteresis caused by transmission clearance in the feedback gear assembly. This makes the valve position detection structure less prone to failure, improving both its service life and reliability, while also enhancing valve position measurement accuracy.

[0032] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0033] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A non-contact valve position detection structure, characterized in that, The device includes a magnetic induction angle sensor fixed inside the housing of a valve positioner for measuring the direction and angle of a magnetic field, and a feedback shaft assembly that non-contactly engages with the magnetic induction angle sensor. The magnetic induction angle sensor is electrically connected to the main board of the valve positioner. The feedback shaft assembly includes a mounting support fixed to the outer surface of the valve positioner housing, a feedback shaft that rotates through the mounting support, and a magnet. The feedback shaft is axially engaged with the mounting support and includes a first end adjacent to the magnetic induction angle sensor and a second end away from the magnetic induction angle sensor. The magnet is fixed to the first end and engages with the magnetic induction angle sensor. The second end is fixedly connected to the valve stem and rotates synchronously with the valve stem.

2. The non-contact valve position detection structure according to claim 1, characterized in that, The feedback shaft assembly also includes a bushing that is inserted into the mounting support and rotatably engages with the feedback shaft.

3. The non-contact valve position detection structure according to claim 2, characterized in that, The mounting support includes a flange fixed to the outer surface of the housing and a limiting cylinder fixedly connected to the flange and extending axially along the feedback shaft. The inner cavity of the limiting cylinder communicates with the central through hole of the flange. The upper inner wall of the limiting cylinder protrudes to form a mounting ring. The mounting ring and the inner wall of the limiting cylinder above it form a first mounting groove. The bushing includes a sleeve inserted into the inner cavity of the limiting cylinder and a limiting ring fixed to the top of the sleeve and located in the first mounting groove. The central opening of the limiting ring communicates with the inner cavity of the sleeve and the central through hole of the flange to form a feedback shaft through channel.

4. The non-contact valve position detection structure according to claim 3, characterized in that, The feedback shaft includes a shaft body, a shoulder fixed to the top of the shaft body, and a cap fixed to the top of the shoulder. The width or diameter of the shaft body, shoulder, and cap increases sequentially. The shaft body passes through the feedback shaft connection channel and extends from below the flange. The lower part of the shaft body is provided with a first connecting groove and a second connecting groove located below the flange. The shoulder and cap are located above the limiting ring. The upper surface of the cap is provided with a non-circular slot for receiving the magnet. The outer contour shape of the magnet is adapted to the inner contour shape of the non-circular slot.

5. The non-contact valve position detection structure according to claim 4, characterized in that, The feedback shaft assembly further includes a first sealing ring embedded in the first connecting groove and limited to the inner wall of the limiting cylinder, a retaining ring embedded in the second connecting groove, a first washer sleeved on the shaft body and located between the first sealing ring and the retaining ring, a feedback shaft indicator sleeved on the shaft body and located below the retaining ring, and a second washer, a third washer, and a fourth washer sequentially sleeved on the shaft shoulder from bottom to top. The upper surface of the first washer abuts against the lower surface of the flange, the lower surface of the first washer abuts against the retaining ring, the feedback shaft indicator is limited to the shaft body along the radial direction of the shaft body, the lower surface of the second washer abuts against the upper surface of the mounting ring, and the upper surface of the fourth washer abuts against the lower surface of the shaft cap.

6. The non-contact valve position detection structure according to claim 1, characterized in that, The magnet is a permanent magnet.

7. A valve positioner, characterized in that, The non-contact valve position detection structure according to any one of claims 1-6 further includes a housing and a main board and an electrical conversion module housed in the inner cavity of the housing, wherein the electrical conversion module is electrically connected to the main board, the magnetic induction angle sensor is fixed in the inner cavity of the housing, and the mounting support is fixed on the outer bottom surface of the housing.

8. The valve positioner according to claim 7, characterized in that, The housing includes an upper cover and a bottom shell located below the upper cover and fixedly connected to the upper cover. The inner bottom surface of the bottom shell is provided with a plurality of mounting studs for fixing the motherboard and a feedback shaft platform located between the plurality of mounting studs. The feedback shaft platform is spaced apart from the mounting studs and is set independently, or the feedback shaft platform is integrally formed with at least a portion of the mounting studs. The feedback shaft platform has a mounting hole extending axially along the feedback shaft and penetrating the upper surface of the feedback shaft platform and the lower surface of the bottom shell. A support plate is provided in the mounting hole. The support plate separates the mounting hole to form a second mounting groove for embedding a magnetic induction angle sensor and a slot located below the second mounting groove. The lower surface of the bottom shell has a limiting groove communicating with the slot opening and used to fix the mounting support. At least a part of the mounting support and the feedback shaft are inserted into the slot.

9. The valve positioner according to claim 8, characterized in that, The support plate separates the mounting holes to form a second, non-communicating mounting groove and slot; or the support plate is annular in structure, with a portion of the magnet or a portion of the magnet and feedback shaft inserted into the annular space of the support plate.

10. The valve positioner according to claim 7, characterized in that, The motherboard includes a housing, a control circuit board housed within the housing, a display screen and buttons mounted on the housing and electrically connected to the control circuit board, a grounding plate soldered to the control circuit board and connected to the internal protective ground of the control circuit board, and mounting screws penetrating the grounding plate and the housing and fixedly connected to the casing.

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