JP2023136655A - Valve opening detector and valve positioner - Google Patents

Abstract

To reduce a risk of damage of components used for detecting valve opening, and suppress wrong detection of the valve opening and deterioration in detection accuracy of the valve opening due to influence of ambient magnetism.SOLUTION: A valve opening detector 20 is a valve opening detector 20 that detects the valve opening of the valve 90, and includes: an encoder 21 that comprises a scale 22 fixed to a member that has a light and dark pattern and is displaced in conjunction with change in the valve opening of the valve 90, and an optical sensor 23B facing the scale 22 and reading a part of the light and dark pattern; and a valve opening derivation circuit 25 that derives the valve opening of the valve based on the part of the light and dark pattern read by the optical sensor 23B.SELECTED DRAWING: Figure 3

Description

The present invention relates to a valve opening degree detector and a valve positioner that detect the opening degree of a valve.

Patent Document 1 discloses a technique for detecting the opening degree of a valve using a pin that interlocks with the valve shaft, a feedback lever that rotates in conjunction with the pin, and a potentiometer that detects the rotation of the feedback lever. There is.

Patent Document 2 discloses a technique for detecting the opening degree of a valve using magnetism using a non-contact position transmitter and a non-contact position receiver.

Japanese Patent Application Publication No. 2003-239901 Special Publication No. 2006-517281

In the technique described in Patent Document 1, for example, since the pin slides with respect to the feedback lever, there is frictional wear and there is a risk of damage over a long period of time. There is also the risk of damaging the pins due to vibration. Although the technique described in Patent Document 2 suppresses the risk of damage, the valve opening degree may be erroneously detected or the detection accuracy of the valve opening degree may decrease due to the influence of surrounding magnetism.

The present invention has been made in view of the above points, and reduces the risk of damage to parts used to detect the valve opening degree, and also prevents erroneous detection of the valve opening degree due to the influence of surrounding magnetism. The challenge is to suppress the decline in detection accuracy.

In order to solve the above problems, a valve opening degree detector according to the present invention is a valve opening degree detector that detects the valve opening degree of a valve, and has a light and dark pattern, and has a light and dark pattern, and is responsive to changes in the valve opening degree of the valve. an encoder comprising a scale fixed to a member that moves in conjunction with the scale; an optical sensor that faces the scale and reads a part of the bright and dark pattern; and the part of the bright and dark pattern read by the optical sensor. and a valve opening degree deriving circuit that derives the valve opening degree of the valve based on the valve opening degree.

As an example, the encoder further includes a light emitting unit that emits light in the bright and dark pattern, and the optical sensor receives the light that is emitted from the light emitting unit and is reflected or transmitted by the scale, thereby forming the bright and dark pattern. reads the above part.

As an example, the encoder is of a reflective type, and the light emitting section and the optical sensor are housed in an explosion-proof container having a light-transmitting window, and face the scale through the window.

As an example, the encoder is of a transmission type, and the light emitting section and the optical sensor are housed in a container having a pair of translucent windows facing each other with the scale interposed therebetween, and the pair of windows and the scale are housed in a container. Opposing through.

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

A valve positioner according to the present invention is a valve positioner equipped with the above-mentioned valve opening degree detector, in which the explosion-proof container is used as a casing, and the valve opening degree of the valve detected by the valve opening degree detector and a target valve opening are determined. and a valve positioner body that controls the valve based on the valve position.

According to the present invention, the risk of damage to parts used to detect the valve opening degree is reduced, and erroneous detection of the valve opening degree and decrease in the detection accuracy of the valve opening degree due to the influence of surrounding magnetism are suppressed. .

FIG. 1 is a configuration diagram of a valve positioner according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along line AA in FIG. FIG. 3 is a block diagram of the valve positioner according to the first embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of the valve positioner according to the first embodiment of the present invention. FIG. 5 is a configuration diagram of a valve positioner according to a second embodiment of the present invention. FIG. 6 is a configuration diagram of a valve positioner according to a third embodiment of the present invention. FIG. 7 is a configuration diagram of a valve positioner according to a fourth embodiment of the present invention. FIG. 8 is a diagram showing the positional relationship between the scale, the light emitting section, and the optical sensor of the valve positioner according to the fourth embodiment of the present invention, as viewed from above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A valve opening degree detector and a valve positioner according to embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
A valve positioner 10 according to the present embodiment shown in FIGS. 1 and 2 is configured to control a valve 90 provided in the middle of a pipe H provided in an industrial plant or the like. The valve positioner 10 includes a valve opening detector 20 (FIG. 3), which will be described later, that detects the opening of the valve 90. The valve positioner 10 controls the valve 90 based on the detected valve opening of the valve 90 and a target valve opening supplied as a target value from a higher-level controller C (FIG. 3), which will be described later. Hereinafter, the valve 90 will be explained, and then the valve positioner 10 will be explained. Note that the valve positioner 10 and the valve 90 constitute a flow control device (control valve).

The valve 90 is configured here as a globe valve, which is a type of direct-acting valve, and controls the flow rate of the fluid flowing through the pipe H. The valve 90 includes a body 91, a valve body 92, a valve shaft 93, a shaft guide portion 94, an actuator 95, and a yoke 96.

The body 91 is a hollow member that is connected to the pipe H and forms a flow path R for fluid flowing through the pipe H. The valve body 92 is disposed within the body 91 and opens and closes the flow path R by moving in the vertical direction.

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

The actuator 95 is supported by a yoke 96 fixed to the shaft guide section 94. The actuator 95 drives the operating shaft 95A in the vertical 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 then 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 are moved in the vertical direction by the driving force from the actuator 95. The opening degree of the valve 90, that is, the flow rate of the fluid, is controlled by the position of the valve body 92.

Valve 90 may be configured as other direct-acting valves such as gate valves and diaphragm valves.

As shown in FIG. 3, the valve positioner 10 includes a valve opening degree detector 20, a communication section 31, a feedback control circuit 32, and an electro-pneumatic conversion section 33.

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

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

In the example of FIGS. 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 operating shaft 93A or the drive shaft 93B via the bracket 81. The scale 22 may be fixed to any member that moves in conjunction with changes in the opening degree of the valve 90. The valve positioner main body 11 may be placed at any fixed position that is not linked to changes in the opening degree of the valve 90.

The scale 22 is a plate-like member provided with a light and dark pattern consisting of high reflectance areas and low reflectance areas (including slits). The light and dark pattern may be an incremental pattern, an absolute pattern, or a two-dimensional code.

As shown in FIGS. 1 and 2, the sensor module 23 is disposed at a position facing the scale 22 through a translucent window W, which will be described later. As shown in FIGS. 1 to 3, the sensor module 23 includes a light emitting section 23A that emits light to the scale 22, and an optical sensor 23B that receives light from the light emitting section 23A that is reflected by the scale 22. The operation of the sensor module 23 (for example, the light emission of the light emitting section 23A) is controlled by, for example, one of the valve opening degree deriving circuit 25 and the feedback control circuit 32, or an arbitrary control circuit (not shown). The light emitting section 23A and the optical sensor 23B face the scale 22 with a translucent window W interposed therebetween. The optical sensor 23B receives the light emitted from the light emitting part 23A and reflected by the scale 22 through the window W, and detects the brightness pattern of a part of the scale 22, that is, the part where the light from the light emitting part 23A is reflected, through the window W. Read through. The light emitting section 23A may be any one of a combination of point-shaped light emitting elements, a linear light source, a planar light source, or the like. The optical sensor 23B may be any combination of a plurality of light receiving elements (such as photodiodes), a line sensor, an area sensor, or the like.

The optical sensor 23B included in the sensor module 23 reads a part of the bright and dark pattern by converting the received light into an electrical signal. The optical sensor 23B supplies the converted electrical signal to the valve opening degree deriving circuit 25 shown in FIG. The content of the brightness pattern converted into an electric signal changes depending on the vertical position of the scale 22, that is, the valve shaft 93. That is, the electric signal represents the position of the valve shaft 93 in the vertical direction.

The valve opening degree deriving circuit 25 shown in FIG. 3 derives the vertical position of the scale 22 based on the electrical signal (read brightness pattern) output by the optical sensor 23B of the sensor module 23. The valve opening degree deriving circuit 25 calculates the vertical position of the scale 22 (relative position to the reference position) by counting the number of changes from dark to bright based on electrical signals sequentially supplied from the optical sensor 23B, for example. Derive (incremental type). The valve opening degree deriving circuit 25 derives the vertical position (absolute position relative to the optical sensor 23B) of the scale 22 based on the contents (including images) of the light and dark pattern represented by the electric signal (absolute type, image position detection using sensors, etc.). The vertical position of the scale 22 corresponds one-to-one to the opening degree of the valve 90. The valve opening degree deriving circuit 25 derives the valve opening degree (actual opening degree) corresponding to the derived position of the scale 22 based on the derived position, and outputs it to the feedback control circuit 32 . The valve opening degree deriving circuit 25 may output the position of the scale 22 as the valve opening degree of the valve 90. By deriving the valve opening degree (actual opening degree) or the position of the scale 22, the valve opening degree is detected.

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

The feedback control circuit 32 uses the valve opening degree from the valve opening degree deriving circuit 25 as a feedback value, uses the target valve opening degree from the communication unit 31 as a target value, and determines the future valve opening degree of the valve 90 based on both. The amount of operation that brings the target value closer to the target value is derived using modern control laws. The feedback control circuit 32 supplies the derived manipulated variable to the electro-pneumatic converter 33.

The electro-pneumatic converter 33 includes a nozzle flapper mechanism, etc., and converts the manipulated variable from the feedback control circuit 32 into an air signal, and sends the converted air signal through the tube 83 (FIGS. 1 and 2). The actuator 95 of the valve 90 is supplied. Note that if the actuator 95 is an electric type, the feedback control circuit 32 supplies the manipulated variable directly to the actuator 95.

Through the above operations, the valve positioner 10 (valve positioner body 11) adjusts the valve position based on the valve opening of the valve 90 detected by the valve opening detector 20 and the target valve opening from the host controller C. Feedback control is performed to control 90.

As schematically shown in FIG. 4, the valve positioner main body 11 of the valve positioner 10 includes a housing 12 having a translucent window W at a position facing the scale 22. The housing 12 includes components other than the scale 22 among the components that realize each function of the valve positioner 10, specifically, a sensor module 23, a valve opening degree deriving circuit 25, a communication section 31, a feedback control circuit 32, and an electric power supply. It houses an empty conversion section 33. The housing 12 is preferably configured as an explosion-proof container having explosion-proof performance. In this case, the window W is preferably made of pressure-resistant glass or the like.

As described above, in this embodiment, since the valve opening degree of the valve 90 is detected by the optical (non-contact type) encoder 21, there is a risk of wear due to contact between parts used to detect the valve opening degree. Furthermore, there is no risk of damage caused by vibration transmission due to contact between parts. Furthermore, since the encoder 21 is of an optical type, detection of the valve opening degree is not affected by surrounding magnetism. As described above, according to the valve opening degree detector 20 and the valve positioner 10 including the same according to the present embodiment, the risk of damage to parts used for detecting the valve opening degree is reduced, and the influence of surrounding magnetism is reduced. Erroneous detection of the valve opening degree and a decrease in the detection accuracy of the valve opening degree due to this are suppressed.

Furthermore, when using a feedback lever as in the past, there may be restrictions on the installation location and installation method of the valve positioner due to its structure and size, but such inconveniences do not occur in this embodiment. Furthermore, the only component installed on the valve 90 side used for detecting the valve opening degree can be the scale, which provides a simple and lightweight structure and high vibration resistance. Additionally, positioning adjustment and confirmation at the time of initial installation become easier.

Further, as in this embodiment, the housing 12 of the valve positioner 10 is preferably made into an explosion-proof container, and parts other than the scale 22 of the valve opening degree detector 20 (such as the encoder 21) are housed in this explosion-proof container. Thereby, explosion-proof performance can be easily obtained for the valve positioner 10. In particular, the scale 22 placed outside the casing 12 as an explosion-proof container does not cause an explosion, so even if the encoder 21 is employed to detect the valve opening with the above configuration, The desired explosion-proof performance can be obtained. Furthermore, if the housing 12 is provided with a light-transmitting window W, the light emitting section 23A and the optical sensor 23B can be provided inside the housing 12, so that explosion-proof performance is ensured with a simple structure.

The light emitting unit 23A may be configured with a light emitting element or the like that emits light in a specific wavelength band, such as a wavelength band that is not affected by disturbance light such as natural light or is small. The optical sensor 23B may be configured with a sensor that is highly sensitive to light in the above-mentioned specific wavelength band. The window W may include a transmission filter or the like that cuts light outside the specific wavelength band. As a result, the influence of external light and the like is reduced, erroneous detection of the valve opening degree is suppressed, and the detection accuracy of the valve opening degree is improved.

[Second embodiment]
As shown in FIG. 5, in the valve positioner 110 according to this embodiment, the sensor module 23 is separated from the valve positioner main body 11 and provided separately. The valve positioner body in which the sensor module 23 is separate is also referred to as the valve positioner body 111. The present embodiment will be described below, focusing on the differences from the first embodiment. Elements having the same functions as those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and detailed description thereof will be omitted (the same applies to the third embodiment and subsequent embodiments). Furthermore, for elements that have the same names as those in the first embodiment but are given different numerals, the explanations of the elements with the same names in the first embodiment apply as appropriate (the same applies to the third embodiment and subsequent embodiments). . Elements with the same name correspond to each other and have similar roles.

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 includes a window W, and the light emitting section 23A and the optical sensor 23B face the scale 22 through the window W. The sensor module 23 communicates by wire or wirelessly with the valve positioner main body 111, which is located at a distance from the explosion-proof container 119, and transmits an electrical signal representing the brightness and darkness pattern of the scale 22 read by the optical sensor 23B to the valve positioner main body 111. supply to. The valve opening degree deriving circuit 25 may be housed in the explosion-proof container 119 instead of on the valve positioner main body 111 side.

According to the embodiments described above, the valve positioner main body 111 can be installed apart from the valve 90, thereby reducing various restrictions (such as the shape of the valve 90) when attaching the positioner main body to the valve. Ru.

[Third embodiment]
As shown in FIG. 6, the valve positioner 210 according to this embodiment employs a transmission type encoder 221. In this case, the housing 212 of the positioner main body 211 includes a recess into which the scale 222 fits. The scale 222 has a light and dark pattern expressed by the presence or absence of a transparent part such as a slit, and extends from the bracket 81 toward the positioner main body 211 side. The housing 212 includes a pair of translucent windows W1 and W2 facing each other with a scale 222 in between, as members forming the inner wall of the recess. The scale 222 and the windows W1 and W2 are spaced apart so that they do not come into contact with each other.

The light emitting section 223A and the optical sensor 223B of the sensor module 223 face the scale 222 via the windows W1 and W2. The optical sensor 223B reads the brightness pattern of the scale 222 by receiving light from the light emitting section 223A that has passed through the scale 222 and the windows W1 and W2.

According to this embodiment, since the scale 222 is sandwiched between the recesses of the housing 212, the recesses can reduce the amount of disturbance light that enters around the scale 222, improving the accuracy of detecting the valve opening degree. . The housing 212 may be configured as an explosion-proof container. Thereby, explosion-proof performance is also provided to the valve positioner 210.

Note that, similarly to the second embodiment, the sensor module 223 may be provided separately from the valve positioner main body 211.

[Fourth embodiment]
As shown in FIGS. 7 and 8, in this 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 body, valve shaft, and the like 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 body when the actuator 395 rotates the valve body, and a disk 397 fixed to the rotation shaft 396. A fan-shaped scale 322 constituting the encoder 321 is fixed to the upper surface of the disc 397.

The positioner 311, which houses the sensor module 23 of the encoder 321 in the housing 312, is fixed to the actuator 395 via a bracket 382. The housing 312 may be provided with a window W through which the light emitted by the light emitting section 23A and the light from the scale 322, which is received by the optical sensor 23B, pass through the reflection hole. The housing 312 may be configured as an explosion-proof container.

The sensor module 23 may be provided separately from the valve positioner 311 similarly to the first embodiment. Further, as the encoder 321, a transmissive encoder may be employed. In this case, the shape of the scale etc. is changed as in the third embodiment. The valve opening degree deriving circuit 25 derives the rotation angle of the scale 322 based on the result of reading the brightness pattern of the scale 322 from the encoder 321. The valve opening degree deriving circuit 25 derives the valve opening degree based on the derived rotation angle and supplies it to the feedback control circuit 32 . The valve opening degree deriving circuit 25 supplies the rotation angle itself to the feedback control circuit 32 as the valve opening degree.

[Modified example]
The shape of each member explained above can be changed as appropriate. Further, the valve opening degree deriving circuit 25 and the feedback control circuit 32 may be constituted 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 a device other than the valve positioner. In order to reduce the influence of external light, a cover or the like may be used to block light between the sensor module 23 and the like and the scale 22 and the like.

[Scope of the present invention]
Although the present invention has been described above with reference to the embodiments and modifications, the present invention is not limited to the embodiments and modifications described above. For example, the present invention includes various modifications to the above-described embodiments and modifications that can be understood by those skilled in the art within the scope of the technical idea of the present invention. The configurations listed in the above embodiments and modified examples can be combined as appropriate within a consistent range.

DESCRIPTION OF SYMBOLS 10... Valve positioner, 11... Valve positioner body, 12... Housing, 20... Valve opening degree detector, 21... Encoder, 22... Scale, 23... Sensor module, 23A... Light emitting part, 23B... Optical sensor, 25... Valve Opening degree derivation circuit, 31...Communication section, 32...Feedback control circuit, 33...Electro-pneumatic conversion section, 81...Bracket, 82...Mounting plate, 83...Tube, 90...Valve, 91...Body, 92...Valve body, 93 ...valve shaft, 93A...operating shaft, 93B...drive shaft, 93C...connector, 94...shaft guide section, 95...actuator, 95A...actuating 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...Casing, 221...Encoder, 222...Scale, 223...Sensor module, 223A...Light emitting part, 223B... Optical sensor , 311... Valve positioner body, 312... Housing, 321... Encoder, 322... Scale, 382... Bracket, 390... Valve, 395... Actuator, 396... Rotating shaft, 397... Disc, C... Upper controller, H... Piping , R...channel, W...window, W1...window, W2...window.

Claims (6)

A valve opening degree detector that detects the opening degree of a valve,
An encoder comprising: a scale fixed to a member that has a light and dark pattern and is displaced in conjunction with changes in the valve opening of the valve; and an optical sensor that faces the scale and reads a part of the light and dark pattern. ,
a valve opening degree deriving circuit that derives the valve opening degree of the valve based on the part of the light and dark pattern read by the optical sensor;
Valve opening detector. The encoder further includes a light emitting unit that emits light in the bright and dark pattern,
The optical sensor reads the part of the bright and dark pattern by receiving the light emitted from the light emitting part and reflected or transmitted by the scale.
The valve opening degree detector according to claim 1. The encoder is of a reflective type,
The light emitting unit and the optical sensor are housed in an explosion-proof container having a translucent window, and are opposed to the scale through the window.
The valve opening degree detector according to claim 2. The encoder is of a transparent type,
The light emitting unit and the optical sensor are housed in a container having a pair of translucent windows facing each other through the scale, and facing each other through the pair of windows and the scale.
The valve opening degree detector according to claim 2. The container has explosion-proof performance,
The valve opening degree detector according to claim 4. A valve positioner comprising the valve opening degree detector according to any one of claims 3 to 5,
The explosion-proof container is a casing, and a valve positioner body is provided that controls the valve based on the valve opening of the valve detected by the valve opening detector and a target valve opening.
valve positioner.

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