CN116771977A - Valve opening detector and valve positioner - Google Patents

Abstract

The purpose of the present invention is to reduce the risk of damage to a component used for detecting a valve opening, and to suppress erroneous detection of the valve opening and a reduction in the detection accuracy of the valve opening due to the influence of surrounding magnetism. The valve opening detector (20) of the present invention is a valve opening detector (20) for detecting a valve opening of a valve (90), and comprises: an encoder (21) provided with a scale having a bright-dark pattern and fixed to a member displaced in conjunction with a change in the valve opening of the valve (90), and a photosensor (23B) facing the scale (22) for reading a part of the bright-dark pattern; and a valve opening deriving circuit (25) that derives the valve opening of the valve from the portion of the bright-dark pattern read by the optical sensor (23B).

Description

Valve opening detector and valve positioner

Technical Field

The present invention relates to a valve opening detector and a valve positioner for detecting a valve opening of a valve.

Background

Patent document 1 discloses the following technique: the valve opening of the valve is detected by a pin that is linked to the valve shaft, a feedback lever that rotates in linkage with the pin, and a potentiometer that detects the rotation of the feedback lever.

Patent document 2 discloses the following technique: the valve opening of the valve is detected by a non-contact position transmitter and a non-contact position receiver using magnetic force.

Prior art literature

Patent literature

[ patent document 1] Japanese patent laid-open publication No. 2003-239901

[ patent document 2] Japanese patent application laid-open No. 2006-517281

Disclosure of Invention

Problems to be solved by the invention

In the technique described in patent document 1, for example, the pin slides against the feedback rod, and thus there is a risk of frictional wear and long-term damage. In addition, there is a risk of damage to the pins due to vibration. In the technique described in patent document 2, although the risk of the damage is suppressed, the valve opening degree or the detection accuracy of the valve opening degree may be erroneously detected due to the influence of the magnetic properties around the valve opening degree.

The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the risk of damage to a component used for detecting a valve opening, and to suppress erroneous detection of the valve opening and a decrease in detection accuracy of the valve opening due to influence of surrounding magnetism.

Technical means for solving the problems

In order to solve the above-described problems, a valve opening detector according to the present invention is a valve opening detector for detecting a valve opening of a valve, the valve opening detector including: an encoder including a scale having a bright-dark pattern and fixed to a member displaced in conjunction with a change in a valve opening of the valve, and a photosensor facing the scale and reading a part of the bright-dark pattern; and a valve opening deriving circuit that derives a valve opening of the valve from the portion of the bright-dark pattern read by the photosensor.

As an example, the encoder may further include a light emitting portion that emits light to the bright-dark pattern, and the optical sensor may read the part of the bright-dark pattern by receiving the light emitted from the light emitting portion and reflected or transmitted by the scale.

As an example, the encoder is a reflection type, and the light emitting unit and the light sensor are housed in an explosion-proof container having a translucent window, and are opposed to the scale through the window.

As an example, the encoder is a transmissive type, and the light emitting unit and the light sensor are housed in a container having a pair of light transmitting windows facing each other through the scale, and face the scale through the pair of windows.

As an example, the container has explosion-proof properties.

The valve positioner according to the present invention is a valve positioner including the valve opening detector, and includes: and a valve positioner body that controls the valve based on the valve opening of the valve detected by the valve opening detector and a target valve opening, using the explosion-proof container as a housing.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to reduce the risk of damage to a component used for detecting the valve opening, and to suppress erroneous detection of the valve opening and a decrease in the detection accuracy of the valve opening due to the influence of surrounding magnetic force.

Drawings

Fig. 1 is a configuration diagram of a valve positioner according to embodiment 1 of the present invention.

Fig. 2 is a sectional view A-A of fig. 1.

Fig. 3 is a block diagram of a valve positioner according to embodiment 1 of the present invention.

Fig. 4 is a schematic cross-sectional view of a valve positioner according to embodiment 1 of the present invention.

Fig. 5 is a configuration diagram of a valve positioner according to embodiment 2 of the present invention.

Fig. 6 is a configuration diagram of a valve positioner according to embodiment 3 of the present invention.

Fig. 7 is a configuration diagram of a valve positioner according to embodiment 4 of the present invention.

Fig. 8 is a diagram showing the positional relationship of the scale, the light emitting unit, and the optical sensor of the valve positioner according to embodiment 4 of the present invention, when the three are viewed from above.

Detailed Description

The valve opening detector and the valve positioner according to the embodiment of the present invention will be described below with reference to the drawings.

[ embodiment 1]

The valve positioner 10 of the present embodiment shown in fig. 1 and 2 is configured to control a valve 90 provided in the middle of a pipe H provided in an industrial facility or the like. The valve positioner 10 includes a valve opening detector 20 (fig. 3) that detects a valve opening of the valve 90, which will be described later. The valve positioner 10 controls the valve 90 based on the detected valve opening of the valve 90 and a target valve opening supplied from a higher-level controller C (fig. 3) described later as a target value. The valve 90 is described below, and then the valve positioner 10 is described. The valve positioner 10 and the valve 90 constitute a flow rate control device (a regulator valve).

Here, the valve 90 is constituted by a ball valve, which is one type of direct-acting valve, and controls the flow rate of the fluid flowing through the pipe H. The valve 90 includes a main body 91, a valve body 92, a valve shaft 93, a shaft guide 94, an actuator 95, and a yoke 96.

The main body 91 is connected to the pipe H, and is a hollow member forming a flow path R of the fluid flowing through the pipe H. The valve body 92 is disposed in the main body 91, and moves in the up-down direction to open and close the flow path R.

The valve shaft 93 is a rod-shaped member that transmits the driving force of the actuator 95 to the valve body 92 and moves the valve body 92 in the up-down direction. The valve shaft 93 includes: an actuation shaft 93A that moves up and down by driving of the actuator 95; a drive shaft 93B connected to the valve body 92 and moving up and down together with the valve body 92 in conjunction with the up-and-down movement of the actuation shaft 93A; and a connector 93C that connects the actuation shaft 93A and the drive shaft 93B. The drive shaft 93B passes through a cylindrical shaft guide 94 connected to the main body 91 and extending in the up-down direction. The shaft guide 94 guides the valve shaft 93 to move in the up-down direction.

The actuator 95 is supported by a yoke 96 fixed to the shaft guide 94. The actuator 95 drives the actuation shaft 95A in the up-down direction under the control of the valve positioner 10. The driving force to the actuation shaft 95A is transmitted to the drive shaft 95B via the connector 95C, and is transmitted to the valve body 92 connected to the drive shaft 95B. In this way, the valve shaft 93 and the valve body 92 connected to the valve shaft 93 move in the up-down direction by the driving force from the actuator 95. The valve opening of the valve 90, i.e., the flow rate of the fluid, is controlled according to the position of the spool 92.

The valve 90 may be constituted by another direct-acting valve such as a gate valve or a diaphragm valve.

As shown in fig. 3, the valve positioner 10 includes a valve opening detector 20, a communication unit 31, a feedback control circuit 32, and an electronic air conversion unit 33.

The valve opening detector 20 includes an optical and reflective encoder 21 and a valve opening deriving circuit 25. Here, the encoder 21 is a linear encoder, and includes a scale 22 and a sensor module 23.

The valve positioner 10 is roughly divided into a scale 22 and a valve positioner body 11 other than the scale 22. As shown in fig. 1 and 2, the scale 22 is fixed to the valve shaft 93 by an L-shaped bracket 81. The valve positioner body 11 is fixed to a yoke 96 of the valve 90 by a plate-like mounting plate 82.

In the example of fig. 1 and 2, the scale 22 is fixed to the connector 93C of the valve shaft 93, but the scale 22 may be fixed to the actuation shaft 93A or the drive shaft 93B by the bracket 81. The scale 22 may be fixed to any member that is displaced in conjunction with the change in the valve opening degree of the valve 90. The valve positioner body 11 may be disposed at an arbitrary position that is not stationary in conjunction with the change in the valve opening degree of the valve 90.

The scale 22 is a plate-like member provided with a bright-dark pattern composed of a portion having a high reflectance and a portion having a low reflectance (including a slit). The light and shade pattern may be an incremental pattern, an absolute pattern, or a two-dimensional code.

As shown in fig. 1 and 2, the sensor module 23 is disposed at a position facing the scale 22 through a translucent window W described later. As shown in fig. 1 to 3, the sensor module 23 includes: a light-emitting portion 23A that emits light to the scale 22, and a light sensor 23B that receives light reflected by the scale 22 from the light-emitting portion 23A. The operation of the sensor module 23 (for example, the light emission of the light emitting unit 23A) is controlled by any one of the valve opening deriving circuit 25 and the feedback control circuit 32 or an arbitrary control circuit (not shown), for example. The light-emitting portion 23A and the light sensor 23B face the scale 22 through the translucent window W. The light sensor 23B receives the light emitted from the light emitting portion 23A and reflected by the scale 22 through the window W, and reads a light-dark pattern of a part of the scale 22, that is, a reflected portion of the light from the light emitting portion 23A through the window W. The light emitting portion 23A may be any of a combination of a plurality of point-like light emitting elements, a linear light source, a planar light source, and the like. The light sensor 23B may be any one of a combination of a plurality of light receiving elements (photodiodes, etc.), a line sensor, a region sensor, and the like.

The photosensor 23B included in the sensor module 23 converts the received light into an electrical signal to read a part of the bright-dark pattern. The photosensor 23B supplies the converted electric signal to the valve opening deriving circuit 25 shown in fig. 3. The content of the bright-dark pattern converted into the electric signal changes according to the position of the scale 22, i.e., the vertical direction of the valve shaft 93. That is, the electric signal indicates the position of the valve shaft 93 in the up-down direction.

The valve opening deriving circuit 25 shown in fig. 3 derives the position of the scale 22 in the up-down direction from the electric signal (read bright-dark pattern) output from the photosensor 23B of the sensor module 23. The valve opening deriving circuit 25 counts the number of changes from dark to light, for example, based on the electric signal sequentially supplied from the optical sensor 23B, thereby deriving the position (relative position to the reference position) of the scale 22 in the up-down direction (incremental position). The valve opening deriving circuit 25 derives the position (absolute position with respect to the photosensor 23B) of the scale 22 in the up-down direction (absolute position, position detection using an image sensor, etc.) based on the content (including an image) of the bright-dark pattern indicated by the electric signal, for example. The positions of the scale 22 in the up-down direction are in one-to-one correspondence with the valve opening degrees of the valves 90. The valve opening deriving circuit 25 derives a valve opening (actual opening) corresponding to the derived position from the position of the scale 22, and outputs the valve opening to the feedback control circuit 32. The valve opening deriving circuit 25 may output the position of the scale 22 as the valve opening of the valve 90. The valve opening degree (actual opening degree) is detected by derivation of the valve opening degree or the position of the scale 22.

The communication unit 31 is configured by a communication module that receives the target valve opening of the valve 90 from the host controller C. The communication unit 31 communicates with the upper controller C in a two-wire system, and receives the target valve opening according to a current signal of 4 to 20 mA. The communication unit 31 supplies the received target valve opening to the feedback control circuit 32.

The feedback control circuit 32 uses the valve opening from the valve opening deriving circuit 25 as a feedback value, and uses the target valve opening from the communication unit 31 as a target value, and derives an operation amount for bringing the valve opening of the valve 90 in the future close to the target value according to the modern control rules and the like. The feedback control circuit 32 supplies the derived operation amount to the electric air conversion unit 33.

The electro-pneumatic conversion unit 33 includes a nozzle shutter mechanism and the like, and is configured to electro-pneumatic convert the operation amount from the feedback control circuit 32 into an air signal and supply the converted air signal to the actuator 95 of the valve 90 via the pipe 83 (fig. 1 and 2). If the actuator 95 is electric, the feedback control circuit 32 directly supplies the operation amount to the actuator 95.

By the above-described operation, the valve positioner 10 (valve positioner main body 11) performs feedback control of the control valve 90 based on the valve opening of the valve 90 detected by the valve opening detector 20 and the target valve opening from the upper controller C.

As schematically shown in fig. 4, the valve positioner body 11 of the valve positioner 10 includes a frame 12, and the frame 12 has a translucent window W at a position facing the scale 22. The housing 12 accommodates components other than the scale 22, specifically, the sensor module 23, the valve opening deriving circuit 25, the communication unit 31, the feedback control circuit 32, and the electronic space converting unit 33, among the components that realize the functions of the valve positioner 10. The frame 12 may be formed of an explosion-proof container having explosion-proof performance. In this case, the window W may be made of pressure-resistant glass or the like.

As described above, in this embodiment, since the valve opening of the valve 90 is detected by the optical (noncontact) encoder 21, there is no risk of abrasion due to contact between the components used in detection of the valve opening or damage due to vibration transmission due to contact between the components. Further, since the encoder 21 is optical, the detection of the valve opening is not affected by the surrounding magnetism. As described above, according to the valve opening detector 20 and the valve positioner 10 provided with the valve opening detector of the present embodiment, it is possible to reduce the risk of damage to the components used for detecting the valve opening, and to suppress erroneous detection of the valve opening and a reduction in the detection accuracy of the valve opening due to the influence of the surrounding magnetism.

Further, when the feedback lever is used as in the prior art, there are cases where restrictions are imposed on the installation site and the installation method of the valve positioner depending on the structure and the size thereof, but such a problem does not occur in the present embodiment. Further, the member provided on the valve 90 side used for detecting the valve opening degree may be a scale alone, and thus the structure is simple and lightweight, and high vibration resistance can be obtained. In addition, positioning adjustment and confirmation at the time of initial setting are also easy.

As in this embodiment, the housing 12 of the valve positioner 10 may be an explosion-proof container, and components (such as the encoder 21) other than the scale 22 of the valve opening detector 20 may be housed in the explosion-proof container. Thus, the valve positioner 10 can easily obtain explosion-proof performance. In particular, since the scale 22 disposed outside the housing 12 as the explosion-proof container does not cause explosion, the above-described configuration can provide desired explosion-proof performance even if the encoder 21 is used for detecting the opening degree of the valve opening. In addition, if the translucent window W is provided in the housing 12, the light emitting portion 23A and the light sensor 23B can be provided inside the housing 12, so that the explosion-proof performance can be ensured by a simple structure.

The light emitting portion 23A may be constituted by a light emitting element or the like that emits light in a specific wavelength band such as a small wavelength band or the like, which is not affected by disturbance light such as natural light. The light sensor 23 may be a sensor having high sensitivity to light in the specific wavelength band. The window W may be provided with a transmission filter or the like for cutting light outside the specific wavelength band. This reduces the influence of disturbance light or the like, suppresses erroneous detection of the valve opening, and improves the detection accuracy of the valve opening.

[ embodiment 2]

As shown in fig. 5, in the valve positioner 110 of the present embodiment, the sensor module 23 is provided separately from the valve positioner main body 11. The valve positioner body in which the sensor module 23 is provided separately is also referred to as a valve positioner body 111. Hereinafter, this embodiment will be described mainly with respect to a portion different from embodiment 1. Elements having the same functions as those of embodiment 1 are denoted by the same reference numerals as those of embodiment 1, and detailed description thereof will be omitted (embodiment 3 and later will be the same). Note that, the description of the elements having the same names as those of embodiment 1 (the same as those of embodiment 3 and later) can be appropriately applied to the elements having the same names as those of embodiment 1. Elements of the same name correspond to each other and have the same effect.

The sensor module 23 is housed in, for example, an explosion-proof container 119 fixed to the mounting plate 82. The explosion-proof container 119 has a window W, and the light emitting portion 23A and the light sensor 23B face the scale 22 through the window W. The sensor module 23 communicates with the valve positioner body 111 disposed at a distance apart from the explosion-proof container 119 by wired or wireless means, and supplies an electric signal indicating the bright-dark pattern of the scale 22 read by the optical sensor 23B to the valve positioner body 111. The valve opening deriving circuit 25 may be housed in the explosion-proof container 119 instead of the valve positioner main body 111.

According to the above embodiment, the valve positioner body 111 can be provided separately from the valve 90, and thus various restrictions (shape of the valve 90, etc.) when the positioner body is attached to the valve can be reduced.

[ embodiment 3 ]

As shown in fig. 6, a transmissive encoder 221 is used in the valve positioner 210 of the present embodiment. In this case, the housing 212 of the positioner main body 211 includes a recess into which the scale 222 enters. The scale 222 is provided with a light-transmitting portion such as a slit to express a bright-dark pattern, and extends from the bracket 81 to the positioner main body 211 side. The housing 212 includes a pair of light-transmitting windows W1 and W2 facing each other with a scale 222 interposed therebetween as members constituting the inner wall of the recess. Scale 222 is spaced from windows W1 and W2 in a non-contacting manner.

The light emitting portion 223A of the sensor module 223 and the light sensor 223B face the scale 222 through the windows W1 and W2. The light sensor 223B receives light from the light emitting portion 223A transmitted through the scale 222 and the windows W1 and W2, thereby reading the bright-dark pattern of the scale 222.

According to the present embodiment, since the scale 222 is sandwiched by the concave portion of the housing 212, the concave portion can reduce the intrusion of disturbance light into the periphery of the scale 222, and the accuracy of detecting the valve opening can be improved. The housing 212 may be formed of an explosion-proof container. Thereby, the valve positioner 210 is also imparted with explosion-proof performance.

In addition, as in embodiment 2, the sensor module 223 may be provided separately from the valve positioner main body 211.

[ embodiment 4 ]

As shown in fig. 7 and 8, in the present embodiment, a rotary encoder 321 is used instead of the linear encoder 21. The valve 390 in this case is a rotary valve such as a butterfly valve or a ball valve. In fig. 7, the valve element, the valve shaft, etc. other than the actuator 395 of the valve 390 are omitted. The valve 390 includes: a rotation shaft 396 that rotates in conjunction with the valve element when the actuator 395 rotates the valve element, and a circular plate 397 fixed to the rotation shaft 396. A sector scale 322 constituting the encoder 321 is fixed to the upper surface of the circular plate 397.

The positioner 311 of the sensor module 23 that houses the encoder 321 in the housing 312 is fixed to the actuator 395 by a bracket 382. The housing 312 may be provided with a window W that transmits light emitted from the light emitting unit 23A and reflected light from the scale 322 received by the light sensor 23B. The frame 312 may be formed of an explosion-proof container.

As in embodiment 1, the sensor module 23 may be provided separately from the valve positioner 311. As the encoder 321, a transmissive encoder may be used. In this case, the shape of the scale is changed as in embodiment 3. The valve opening deriving circuit 25 derives the rotation angle of the scale 322 from the result of reading the bright-dark pattern of the scale 322 from the encoder 321. The valve opening deriving circuit 25 derives a valve opening from the derived rotation angle, and supplies the valve opening to the feedback control circuit 32. The valve opening deriving circuit 25 supplies the rotation angle itself as the valve opening to the feedback control circuit 32.

Modification example

The shape and the like of each member described above may be changed as appropriate. The valve opening deriving circuit 25 and the feedback control circuit 32 may be configured by a control circuit such as a common processor. The valve opening detected by the valve opening detector 20 or the like may be used by other devices than the valve positioner. In order to reduce the influence of the disturbance light, the sensor module 23 and the scale 22 may be shielded from light by a cover or the like.

[ scope of the invention ].

The present invention has been described above with reference to the embodiments and modifications, but the present invention is not limited to the embodiments and modifications. For example, the present invention includes various modifications of the above-described embodiments and modifications, which can be understood by those skilled in the art within the scope of the technical idea of the present invention. The respective configurations listed in the above embodiments and modifications may be appropriately combined within a range where no contradiction exists.

Symbol description

10 valve positioner, 11 valve positioner body, 12 frame, 20 valve opening detector, 21 encoder, 22 scale, 23 sensor module, 23A light emitting part, 23B light sensor, 25 valve opening deriving circuit, 31 communication part, 32 feedback control circuit, 33 electronic space transforming part, 81 bracket, 82 mounting plate, 83 tube, 90 valve, 91 main body, 92 valve core, 93 valve shaft, 93A actuation shaft, 93B drive shaft, 93C connector, 94 shaft guiding part, 95 actuator, 95A actuation shaft, 95B drive shaft, 95C connector, 96 yoke, 110 valve positioner, 111 valve positioner main body, 119 explosion proof container, 210 valve positioner, 211 valve positioner main body, 212 frame, 221 encoder, 222 scale, 223 sensor module, 223A light emitting part, 223B light sensor, 311 valve positioner main body, 312 frame, 321 encoder, 322 scale, 382 bracket, 390 valve, 395 actuator, 396 rotary shaft, 397 circular plate, C upper controller, H pipe, R flow path, W window, W1 window, W2 window.

Claims (6)

1. A valve opening detector that detects a valve opening of a valve, the valve opening detector comprising:

an encoder that includes a scale having a bright-dark pattern and fixed to a member displaced in conjunction with a change in a valve opening of the valve, and a photosensor that faces the scale and reads a part of the bright-dark pattern; and

and a valve opening deriving circuit that derives a valve opening of the valve from the portion of the bright-dark pattern read by the photosensor.

2. The valve opening detector according to claim 1, wherein,

the encoder further includes a light emitting unit that emits light to the bright-dark pattern,

the light sensor reads the portion of the bright-dark pattern by receiving the light emitted from the light emitting portion and reflected or transmitted by the scale.

3. The valve opening detector according to claim 2, wherein,

the encoder is of the reflective type and,

the light emitting unit and the light sensor are housed in an explosion-proof container having a translucent window, and are opposed to the scale through the window.

4. The valve opening detector according to claim 2, wherein,

the encoder is of a light-transmitting type,

the light emitting unit and the light sensor are housed in a container having a pair of light transmissive windows, the pair of windows being opposed to each other with the scale interposed therebetween, and the light emitting unit and the light sensor being opposed to each other with the pair of windows and the scale interposed therebetween.

5. The valve opening detector according to claim 4, wherein,

the container has explosion-proof properties.

6. A valve positioner provided with the valve opening detector according to any one of claims 3 to 5, characterized in that,

the valve positioner body is provided with a valve positioner body which takes the explosion-proof container as a frame body and controls the valve according to the valve opening of the valve and the target valve opening detected by the valve opening detector.