Linear displacement detection system, valve positioner, and valve opening degree meter

Abstract

To reduce power consumption in a linear displacement detection system.SOLUTION: A switching unit 104 switches magnetic sensors 102a and 102b to be operated to magnetic sensors 102a and 102b adjacent in a direction 151 in which a displacement unit 101 is displaced by determining which region (detection region) a relative position calculated by an arithmetic unit 103 belongs to. The switching unit 104 determines which detection region the relative position calculated by the arithmetic unit 103 belongs to on the basis of information on detection regions of respective magnetic sensors 102a and 102b defined by a known arrangement interval between the magnetic sensors 102a and 102b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a linear displacement detection system, a valve positioner, and a valve opening meter. [Background technology]

[0002] A known position detection device is a magnetic type position detection device that detects the position of a magnet by detecting the magnetic field of the magnet. For example, there is a technology that uses a magnetic sensor to detect the angular change of the magnetic field vector emitted from a magnet moving in a linear direction, and then converts the linear movement of the magnet into an angle to identify the linear position (Patent Document 1, Patent Document 2).

[0003] For accurate angle detection, it is important to apply a sufficient magnetic field to the magnetic sensor. Conventional linear displacement detection systems using magnets use multiple magnetic sensors to expand the detection range and ensure that a sufficient magnetic field is applied to the magnetic sensors (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-107440 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned technology has a problem in that it consumes a lot of power because it uses a plurality of magnetic sensors.

[0006] The present invention has been made to solve the above problems, and has as its object to reduce power consumption in a linear displacement detection system. [Means for solving the problem]

[0007] The linear displacement detection system of the present invention comprises a displacement unit having a magnetization unit, magnetic sensors arranged at intervals at multiple locations in the direction of displacement of the displacement unit and detecting angular changes in a magnetic field vector, a calculation unit configured to calculate the relative position between the displacement unit and the magnetic sensor based on the angular change in the magnetic field vector due to the displacement of the displacement unit detected by the magnetic sensor, and a switching unit configured to switch the operating magnetic sensor to an adjacent magnetic sensor in the direction of displacement of the displacement unit by determining to which region the relative position calculated by the calculation unit belongs.

[0008] The linear displacement detection system of the present invention comprises a displacement unit having a magnetization unit, main magnetic sensors arranged at intervals at multiple locations in the direction of displacement of the displacement unit and detecting angular changes in the magnetic field vector, a calculation unit configured to calculate the relative position between the displacement unit and the main magnetic sensor based on the angular change in the magnetic field vector due to the displacement of the displacement unit detected by the main magnetic sensor, sub-magnetic sensors arranged at intervals at multiple locations in the direction of displacement of the displacement unit at the same position as the main magnetic sensor but farther away from the main magnetic sensor when viewed from the side on which the displacement unit is located and detecting the magnitude of the magnetic field strength, and a switching unit configured to switch the main magnetic sensor that operates based on the magnitude of the magnetic field strength detected by the sub-magnetic sensor.

[0009] In one configuration example of the linear displacement detection system, the magnetizing portion is a permanent magnet.

[0010] The valve positioner according to the present invention detects and controls the opening of the valve as a displacement of the valve using the linear displacement detection system described above.

[0011] The valve opening meter according to the present invention detects and displays the valve opening as a valve displacement using the linear displacement detection system described above. [Effects of the Invention]

[0012] As described above, according to the present invention, the magnetic sensors that operate among the magnetic sensors provided at a plurality of locations are switched, so that the power consumption in the linear displacement detection system can be reduced. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a configuration diagram showing the configuration of a linear displacement detection system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a configuration diagram showing the configuration of a linear displacement detection system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] A linear displacement detection system according to an embodiment of the present invention will be described below.

[0015] [Embodiment 1] First, a linear displacement detection system according to a first embodiment of the present invention will be described with reference to FIG. 1. This linear displacement detection system includes a displacement unit 101, magnetic sensors 102a and 102b provided at multiple locations, a calculation unit 103, and a switching unit 104. This linear displacement detection system is applicable, for example, to a valve positioner that detects and controls the displacement of a controlled object, such as the valve stem displacement of a control valve. This valve positioner detects and controls the opening of a valve as valve displacement using the linear displacement detection system according to the embodiment. Furthermore, this linear displacement detection system is applicable, for example, to a valve position indicator that detects and displays the opening of a valve as valve displacement using the linear displacement detection system according to the embodiment. This valve position indicator detects and controls the opening of a valve as valve displacement using the linear displacement detection system according to the embodiment.

[0016] The displacement portion 101 includes a magnetized portion 111. The magnetized portion 111 can be a permanent magnet. The magnetic sensors 102a and 102b are arranged at intervals at multiple locations in the direction 151 in which the displacement portion 101 is displaced, and detect angular changes in the magnetic field vector. In this example, two magnetic sensors 102a and 102b are provided, but the number of magnetic sensors is not limited to two and can be three or more. The arrangement interval of the magnetic sensors 102a and 102b is determined by design and is known.

[0017] Each of the magnetic sensors 102a and 102b is fixed to a position where it can sense (detect) the magnetic field generated by the magnetized portion 111. The magnetic sensors 102a and 102b are sensors that detect magnetic fields using the magnetoresistance effect, and their electrical resistance changes with changes in the magnetic field. The magnetic sensors 102a and 102b can be configured using, for example, an anisotropic magnetoresistance effect (AMR) element, a giant magnetoresistance effect (GMR) element, or a tunnel magnetoresistance effect (TMR) element.

[0018] The calculation unit 103 calculates the relative position between the displacement unit 101 and the magnetic sensor 102a or 102b based on the angular change in the magnetic field vector caused by the displacement of the displacement unit 101 detected by the magnetic sensors 102a and 102b. When the displacement unit 101, which includes the magnetization unit 111, passes by the magnetic sensors during linear movement (displacement), the magnetic field vector from the magnetization unit 111 changes at the magnetic sensor. This change in the magnetic field vector can be detected by the magnetic sensors. The calculation unit 103 has a built-in approximation curve obtained from the state of the magnetic field vector detected by the magnetic sensor and the positional relationship of the magnetization unit 111. In position measurement, the position of the displacement unit 101 is determined based on the output information of the magnetic sensors and information on the approximation curve. The calculation unit 103 outputs the calculated position information to a higher-level device, for example, via a network.

[0019] The switching unit 104 determines which area (detection area) the relative position calculated by the calculation unit 103 belongs to, and switches the operating magnetic sensors 102a and 102b to the magnetic sensors 102a and 102b adjacent to each other in the direction 151 of displacement of the displacement unit 101. The switching unit 104 determines which detection area the relative position calculated by the calculation unit 103 belongs to based on information about the detection areas of the magnetic sensors 102a and 102b, which is defined by the known arrangement interval of the magnetic sensors 102a and 102b. For example, the calculation required to detect linear movement (displacement) is performed in advance based on the magnetic field characteristics of the magnet used as the magnetization unit 111. From this calculation result and the known arrangement interval of the magnetic sensors 102a and 102b, the detection area in which each of the magnetic sensors 102a and 102b detects (can detect) the magnetic field generated by the magnetization unit 111 can be determined.

[0020] For example, when the calculation unit 103 determines that the relative position calculated by the magnetic sensor 102a falls within the detection area of ​​the magnetic sensor 102b while the magnetic sensor 102a is in operation, the switching unit 104 stops the operation of the magnetic sensor 102a to put it in an inactive state and puts the magnetic sensor 102b in an active state. The supply of power to the inactive magnetic sensor is also stopped.

[0021] If the magnetic sensors 102a and 102b are arranged (distributed) so that an area where the detection areas of the magnetic sensors 102a and 102b overlap is formed, the above-mentioned switching unit 104 can make a judgment in the area where the relative positions overlap.

[0022] As described above, according to the first embodiment, there is always one magnetic sensor that detects the magnetic field generated by the magnetization unit, and the power supply to other magnetic sensors that are in an inoperative state is stopped, thereby reducing the power consumption in the linear displacement detection system.

[0023] [Embodiment 2] Next, a linear displacement detection system according to a second embodiment of the present invention will be described with reference to FIG. 2. This linear displacement detection system includes a displacement unit 101, main magnetic sensors 102'a and 102'b provided at multiple locations, a calculation unit 103, a switching unit 105, and sub-magnetic sensors 112a and 112b. This linear displacement detection system is applicable, for example, to a valve positioner that detects and controls the displacement of a controlled object, such as the valve stem displacement of a control valve. This valve positioner detects and controls the valve opening as valve displacement using the linear displacement detection system according to the embodiment. Furthermore, this linear displacement detection system is applicable, for example, to a valve position indicator that detects and displays the valve opening as valve displacement using the linear displacement detection system according to the embodiment. This valve position indicator detects and controls the valve opening as valve displacement using the linear displacement detection system according to the embodiment.

[0024] The displacement portion 101 includes a magnetized portion 111. The magnetized portion 111 can be a permanent magnet. The main magnetic sensors 102'a and 102'b are arranged at intervals at multiple locations in the direction 151 in which the displacement portion 101 is displaced, and detect angular changes in the magnetic field vector. While this example shows an example in which two main magnetic sensors 102'a and 102'b are provided, the number of magnetic sensors is not limited to two and can be three or more. The arrangement interval of the main magnetic sensors 102'a and 102'b is determined by design and is known.

[0025] Each of the main magnetic sensors 102'a and 102'b is fixed to a position where it can sense (detect) the magnetic field generated by the magnetized portion 111. The main magnetic sensors 102'a and 102'b are sensors that detect the magnetic field using the magnetoresistance effect, and their electrical resistance changes with changes in the magnetic field. The main magnetic sensors 102'a and 102'b can be configured, for example, with an anisotropic magnetoresistance effect (AMR) element, a giant magnetoresistance effect (GMR) element, or a tunnel magnetoresistance effect (TMR) element.

[0026] The calculation unit 103 calculates the relative position between the displacement unit 101 and the main magnetic sensor 102'a or 102'b based on the angular change in the magnetic field vector caused by the displacement of the displacement unit 101 detected by the main magnetic sensors 102'a and 102'b. When the displacement unit 101, which includes the magnetization unit 111, passes through the main magnetic sensors during linear movement (displacement), the magnetic field vector from the magnetization unit 111 changes at the main magnetic sensor. This change in the magnetic field vector can be detected by the main magnetic sensor. The calculation unit 103 has a built-in approximation curve obtained from the state of the magnetic field vector detected by the main magnetic sensor and the positional relationship of the magnetization unit 111. In position measurement, the position of the displacement unit 101 is determined based on the output information of the main magnetic sensor and information on the approximation curve. The calculation unit 103 outputs the calculated position information to a higher-level device, for example, via a network.

[0027] The sub-magnetic sensors 112a, 112b are arranged in the same positions as the main magnetic sensors 102'a, 102'b, but farther away from the main magnetic sensors 102'a, 102'b when viewed from the side where the displacement portion 101 is arranged. The sub-magnetic sensors 112a, 112b are arranged at intervals at multiple locations in the direction 151 in which the displacement portion 101 is displaced, and detect the strength of the magnetic field. The same number of sub-magnetic sensors 112a, 112b as the main magnetic sensors 102'a, 102'b are arranged. When three main magnetic sensors are provided, three sub-magnetic sensors are also arranged.

[0028] The switching unit 105 switches between the active main magnetic sensors 102'a and 102'b based on the magnitude of the magnetic field strength detected by the sub-magnetic sensors 112a and 112b. For example, if the magnetic field strength detected by the sub-magnetic sensor 112a is greater than that of the sub-magnetic sensor 112b, the switching unit 104 stops the operation of the main magnetic sensor 102'b, placing it in an inactive state, and places the main magnetic sensor 102'a in an active state. Also, if the magnetic field strength detected by the sub-magnetic sensor 112b is greater than that of the sub-magnetic sensor 112a, the switching unit 104 stops the operation of the main magnetic sensor 102'a, placing it in an inactive state, and places the main magnetic sensor 102'b in an active state. Furthermore, when three or more sub-magnetic sensors are used, the main magnetic sensor corresponding to the sub-magnetic sensor that detects the greatest magnetic field strength is placed in an active state, and the other main magnetic sensors are placed in an inactive state. Power supply to the inactive magnetic sensors is also stopped.

[0029] As described above, according to the second embodiment, there is always one magnetic sensor that detects the magnetic field generated by the magnetization unit, and the power supply to other magnetic sensors that are not in operation is stopped, thereby reducing the power consumption in the linear displacement detection system.

[0030] As described above, according to the embodiment of the present invention, the magnetic sensors that operate among the magnetic sensors provided at multiple locations are switched, thereby making it possible to reduce power consumption in the linear displacement detection system.

[0031] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0032] 101...displacement section, 102a, 102b...magnetic sensors, 103...calculation section, 104...switching section, 105...switching section, 151...displacement direction, 102'a, 102'b...main magnetic sensors, 112a, 112b...sub-magnetic sensors.

Claims

1. a displacement section including a magnetization section; magnetic sensors arranged at intervals in a plurality of locations in the direction of displacement of the displacement portion, for detecting an angular change of a magnetic field vector; a calculation unit configured to calculate a relative position between the displacement unit and the magnetic sensor based on an angle change of a magnetic field vector caused by the displacement of the displacement unit detected by the magnetic sensor; and a switching unit configured to switch the operating magnetic sensor to the magnetic sensor adjacent to the direction in which the displacement unit is displaced by determining to which region the relative position calculated by the calculation unit belongs; A linear displacement sensing system comprising:

2. a displacement section including a magnetization section; a plurality of main magnetic sensors arranged at intervals in a direction in which the displacement portion is displaced, the main magnetic sensors detecting an angular change of the magnetic field vector; a calculation unit configured to calculate a relative position between the displacement portion and the main magnetic sensor based on an angle change of a magnetic field vector caused by the displacement of the displacement portion detected by the main magnetic sensor; sub-magnetic sensors arranged at intervals in a direction in which the displacement section is displaced, at the same positions as the main magnetic sensor but farther from the main magnetic sensor as seen from the side where the displacement section is disposed, for detecting the magnitude of magnetic field intensity; a switching unit configured to switch the main magnetic sensor that operates based on the magnitude of the magnetic field intensity detected by the sub-magnetic sensor; A linear displacement sensing system comprising:

3. 3. The linear displacement detection system according to claim 1, The linear displacement sensing system, wherein the magnetizing portion is a permanent magnet.

4. A valve positioner that detects and controls the opening of a valve as a valve displacement using the linear displacement detection system according to any one of claims 1 to 3.

5. A valve opening meter that detects and displays the opening of a valve as a valve displacement using the linear displacement detection system according to any one of claims 1 to 3.

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