Linear displacement detection system, valve positioner and valve opening meter

Abstract

The invention provides a linear displacement detection system, a valve positioner and a valve opening meter, which can effectively utilize a detectable area of a magnetic sensor in the whole area. The linear displacement detection system is provided with a displacement unit (101), a magnetic sensor (102), and a calculation unit (103). The displacement part (101) is provided with magnetized parts (111, 112) which are arranged in the displacement direction (151) and are provided at a plurality of locations at intervals. The adjacent magnetized parts (111, 112) have different magnetic poles on the magnetic sensor (102) side. The interval between the adjacent magnetized parts (111, 112) is set to a range in which the magnetic sensor (102) can be used to detect the intensity of the magnetic field formed at the intermediate position between the adjacent magnetized parts (111, 112) in a state in which the magnetic sensor (102) is disposed at the intermediate position between the adjacent magnetized parts (111, 112), and the magnetic sensor (102) can be used to detect the intensity of the magnetic field formed at the intermediate position between the adjacent magnetized parts (111, 112) in a state in which the magnetic sensor (102) is disposed at the intermediate position between the adjacent magnetized parts (111, 112).

Description

Technical Field

[0001] This invention relates to a linear displacement detection system, a valve positioner, and a valve opening meter. Background Technology

[0002] As a position detection device, there is a known magnetic position detection device that detects the position of a magnet by detecting the magnetic field of the magnet. For example, there is a technique that uses a magnetic sensor to detect the angular change of the magnetic field vector emitted from a magnet moving in a straight line, and replaces the linear movement of the magnet with an angle to determine the position in the straight line (Patent Document 1, Patent Document 2).

[0003] To achieve accurate angle detection, a sufficient magnetic field must be applied to the magnetic sensor, and the detectable displacement range is limited by the distance between the magnet and the sensor. Furthermore, even simply increasing the size of the magnet does not result in a sufficiently large change in the angle of the detectable magnetic field vector. In the technology of Patent Document 1, multiple magnetic sensors are used to expand the detection range.

[0004] [Existing Technical Documents] [Patent Literature] Patent Document 1: U.S. Patent No. 10571305 Patent Document 2: U.S. Patent Application Publication No. 2020 / 0191546 Summary of the Invention [The problem the invention aims to solve] However, the aforementioned prior art has the following problem: when it is required to take into account both the strength of the magnetic field and the change in the vector angle of each displacement, it is impossible to effectively utilize the detectable area of ​​the magnetic sensor throughout the entire region.

[0005] This invention was made to solve the problems mentioned above, and its purpose is to effectively utilize the detectable area of ​​the magnetic sensor throughout the entire region.

[0006] [Technical means to solve the problem] The linear displacement detection system of the present invention includes: a displacement unit having magnetized parts arranged at intervals along the direction of displacement at multiple locations; a magnetic sensor fixed at a location capable of detecting the magnetic field formed by the magnetized parts; and a calculation unit configured to calculate the relative position of the displacement unit and the magnetic sensor based on the angular change of the magnetic field vector caused by the displacement of the displacement unit detected by the magnetic sensor. In adjacent magnetized parts, the magnetic poles on the magnetic sensor side are different, and the interval between adjacent magnetized parts is set to a range such that, when a magnetic sensor is arranged at the middle position of adjacent magnetized parts, the intensity of the magnetic field formed at the middle position of adjacent magnetized parts can be detected by the magnetic sensor.

[0007] In one example of the linear displacement detection system, the magnetization part is a permanent magnet, and the displacement part includes permanent magnets arranged at intervals along the direction of displacement and disposed at multiple locations.

[0008] In one structural example of the linear displacement detection system, the permanent magnet is configured as a cuboid.

[0009] The valve positioner of the present invention includes the linear displacement detection system, which uses the linear displacement detection system to detect the valve opening as the valve displacement and control it.

[0010] The valve opening gauge of the present invention includes the linear displacement detection system, which uses the linear displacement detection system to detect the valve opening as the valve displacement and display it.

[0011] [The effects of the invention] As explained above, according to the present invention, the interval between adjacent magnetized sections is set to such a range that, when a magnetic sensor is arranged at the middle position of adjacent magnetized sections, the intensity of the magnetic field formed at the middle position of adjacent magnetized sections can be detected by the magnetic sensor, and thus the detectable area of ​​the magnetic sensor can be effectively utilized throughout the entire region. Attached Figure Description

[0012] Figure 1 This is a structural diagram illustrating the structure of a linear displacement detection system according to an embodiment of the present invention.

[0013] Figure 2 It is a characteristic diagram showing the changes in the magnetic field strength and magnetic field vector detected by the magnetic sensor relative to the different positions of the magnetizing part and the magnetic sensor.

[0014] Figure 3 It is a characteristic diagram showing the changes in the magnetic field strength and magnetic field vector detected by the magnetic sensor relative to the different positions of the magnetizing part and the magnetic sensor.

[0015] Figure 4It is a characteristic diagram showing the changes in the magnetic field strength and magnetic field vector detected by the magnetic sensor relative to the different positions of the magnetizing part and the magnetic sensor.

[0016] Figure 5 It is a characteristic diagram showing the changes in the magnetic field strength and magnetic field vector detected by the magnetic sensor relative to the different positions of the magnetizing part and the magnetic sensor.

[0017] Figure 6 It is a characteristic diagram showing the changes in the magnetic field strength and magnetic field vector detected by the magnetic sensor relative to the different positions of the magnetizing part and the magnetic sensor.

[0018] Explanation of icon numbers 101: Displacement section 102: Magnetic sensor 103: Computation Department 111: Magnetization section 112: Magnetization section 151: Direction of displacement Detailed Implementation The following is for reference Figure 1 This invention describes a linear displacement detection system according to an embodiment of the present invention. The linear displacement detection system includes a displacement unit 101, a magnetic sensor 102, and a calculation unit 103. The linear displacement detection system can be applied, for example, to a valve positioner. The valve positioner utilizes the linear displacement detection system of the embodiment to detect the valve opening degree as valve displacement and performs control. Furthermore, the linear displacement detection system can be applied, for example, to a valve opening gauge. The valve opening gauge utilizes the linear displacement detection system of the embodiment to detect the valve opening degree as valve displacement and displays it.

[0019] The displacement unit 101 includes magnetizing portions 111 and 112, which are arranged at intervals along the displacement direction 151 and disposed at multiple locations. The magnetic poles on the magnetic sensor 102 side are different in adjacent magnetizing portions 111 and 112. Magnetizing portions 111 and 112 can be permanent magnets. The magnetizing portions 111 and 112, acting as magnets, are arranged at intervals along the displacement direction 151 and disposed at multiple locations. The permanent magnets constituting magnetizing portions 111 and 112 can be rectangular in shape.

[0020] The magnetic sensor 102 is fixed at a location capable of detecting the magnetic field formed by the magnetization sections 111 and 112. The magnetic sensor 102 is a sensor that uses the magnetoresistive effect to detect the magnetic field; the resistance changes according to the change in the magnetic field. The magnetic sensor 102 may include, for example, an anisotropic magnetoresistive effect (AMR) element, a giant magnetoresistive effect (GMR) element, and a tunneling magnetoresistive effect (TMR) element.

[0021] The arithmetic unit 103 calculates the relative position of the displacement unit 101 and the magnetic sensor 102 based on the angular change of the magnetic field vector caused by the displacement of the displacement unit 101 detected by the magnetic sensor 102. The arithmetic unit 103 outputs the calculated position information to a host computer, for example, via a network.

[0022] Here, the interval between adjacent magnetized sections 111 and 112 is set to such a range that, when a magnetic sensor 102 is disposed at the middle position of adjacent magnetized sections 111 and 112, the magnetic sensor 102 can be used to detect the strength of the magnetic field formed at the middle position of adjacent magnetized sections 111 and 112.

[0023] When the magnetized part (magnet) in the displacement section passes through the magnetic sensor during linear movement (displacement), the magnetic field vector from the magnetized part changes at the magnetic sensor location. This change in magnetic field vector can be detected using the magnetic sensor. For accurate detection of the magnetic field vector using the magnetic sensor, it is important to apply a sufficient magnetic field to the sensor. For example, in the case of an AMR sensor (kmt37) manufactured by TE Connectivity, a magnetic field of 25 kA / m or higher (saturation magnetic field) is required to ensure sufficient accuracy. Furthermore, the range of detectable displacement is limited depending on the distance between the magnet and the sensor. For example, there are cases where even with a larger magnet to generate a larger magnetic field, the angular change in the magnetic field vector is still insufficient.

[0024] As mentioned above, in the detection of linear displacement, the strength of the magnetic field arriving along the straight direction and the amount of change in the vector angle of each displacement are important. However, in the previous linear displacement detection using magnets, if both the strength of the magnetic field and the amount of change in the vector angle of each displacement are taken into account, it is impossible to use the detectable area of ​​the magnetic sensor in the entire region.

[0025] For example, in the case of a magnetized part (magnet), the magnetic field vector detected by the magnetic sensor varies with the relative position of the magnetized part and the magnetic sensor, such as... Figure 2 The change is as shown by the straight line. Furthermore, when the length of the displacement direction of the magnetization section is increased, for example, when two magnets are simply arranged, the magnetic field vector detected by the magnetic sensor changes relative to the relative position of the magnetization section and the magnetic sensor, as shown by the straight line. Figure 3 The change is as shown by the straight line. Additionally, in Figure 2 , Figure 3 In the diagram, dashed lines represent the variations in magnetic field strength relative to the relative positions of the magnetizing part and the magnetic sensor. (The following will be discussed further.) Figure 4 , Figure 5 , Figure 6 The same applies.

[0026] Based on these simulation results, when using a magnetic sensor with a detection angle range of 180°, only about half of the sensor's detectable area can be effectively utilized within a magnetized region. Furthermore, according to... Figure 2 and Figure 3 The comparison clearly shows that, by simply increasing the size of the magnet, the change in the magnetic field vector detected by the magnetic sensor relative to the different relative positions becomes smaller.

[0027] On the other hand, when two magnetized portions with different magnetic poles on the magnetic sensor side are arranged at an appropriate interval, the magnetic field vectors detected by the magnetic sensor differ relative to the relative positions of the two magnetized portions and the magnetic sensor, such as... Figure 4 The change is as shown by the straight line. According to... Figure 4 It is clear that by arranging the two magnetization sections at an appropriate interval, the change in the magnetic field vector detected by the magnetic sensor relative to the different relative positions becomes larger.

[0028] By arranging the two magnetized sections with different magnetic poles on the magnetic sensor side at appropriate intervals, it is possible to effectively utilize approximately the entire detectable area of ​​the magnetic sensor. Furthermore, according to... Figure 4 It is clear that by arranging the two magnetized sections with different magnetic poles on the magnetic sensor side at an appropriate interval, the change in the magnetic field vector per unit displacement is increased. Thus, it is clear that by increasing the change in the magnetic field vector per unit displacement, differences in relative position can be detected more accurately.

[0029] In addition, if like Figure 5 As shown, further narrowing the distance between the two magnetized parts with different magnetic poles on the magnetic sensor side, then according to Figure 4 and Figure 5 A comparison clearly shows that the sensing distance will become shorter. Therefore, it is preferable to increase the distance between the two magnetized parts as much as possible.

[0030] On the other hand, if like Figure 6 As shown, if the distance between the two magnetized sections with different magnetic poles on the magnetic sensor side is too wide, the magnetic field between the two magnetized sections will be weak. Therefore, it is impossible to achieve continuous position detection with guaranteed accuracy. Moreover, the change in the detected angle becomes smaller between the two magnetized sections, which also makes it impossible to guarantee accuracy.

[0031] As explained above, according to an embodiment of the present invention, a plurality of magnetized portions are provided at intervals along the direction of displacement. The interval between adjacent magnetized portions is set to such a range that, when a magnetic sensor is provided at the middle position of adjacent magnetized portions, the intensity of the magnetic field formed at the middle position of adjacent magnetized portions can be detected by the magnetic sensor. Therefore, the detectable area provided by the magnetic sensor can be effectively utilized throughout the entire region.

[0032] Furthermore, the present invention is not limited to the embodiments described above. It is obvious that, within the technical concept of the present invention, various modifications and combinations can be implemented by those skilled in the art.

Claims

1. A linear displacement detection system, characterized in that, include: The displacement section includes magnetization sections arranged at intervals along the direction of displacement in multiple locations; A magnetic sensor is fixed at a location capable of detecting the magnetic field generated by the magnetized part; as well as The arithmetic unit is configured to calculate the relative position of the displacement unit and the magnetic sensor based on the angular change of the magnetic field vector caused by the displacement of the displacement unit, as detected by the magnetic sensor. In adjacent magnetized sections, the magnetic poles on the magnetic sensor side are different. The spacing between adjacent magnetized sections is set to such a range that, when the magnetic sensor is disposed at the middle position of adjacent magnetized sections, the intensity of the magnetic field formed at the middle position of adjacent magnetized sections can be detected by the magnetic sensor.

2. The linear displacement detection system according to claim 1, characterized in that, The magnetized part is a permanent magnet. The displacement section includes: permanent magnets arranged at intervals along the direction of displacement and disposed at multiple locations.

3. The linear displacement detection system according to claim 2, characterized in that, The permanent magnet is designed as a cuboid.

4. A valve positioner, characterized in that, include: The linear displacement detection system according to any one of claims 1 to 3, The valve positioner uses the linear displacement detection system to detect the valve opening as the valve displacement and then controls it.

5. A valve opening gauge, characterized in that, include: The linear displacement detection system according to any one of claims 1 to 3, The valve opening gauge uses the linear displacement detection system to detect the valve opening as the valve displacement and display it.

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