JP7375381B2 - Eccentric valve device and its control method - Google Patents

Description

The present invention relates to an eccentric valve device and a control method thereof.

Conventionally, piping systems that make up production processes such as factories have incorporated valve devices to control the flow of various gases, liquids, powders, and mixtures thereof (hereinafter simply referred to as fluids, etc.). . The flow path in the piping is shut off or opened by opening and closing the valve body of the valve device. For example, a valve device with an automatic operation function can open and close a valve body without manual operation.

In general, a valve device with an automatic operation function includes a substantially cylindrical valve box having an opening communicating with a flow path, a ring-shaped seat member attached around the opening in the valve box, and a valve box. a valve element that is rotatably provided within the interior and blocks a flow path by being pressed against a seat member, a valve drive section that rotates the valve body, and a control section that controls driving of the valve drive section. It is equipped with

In the valve device, various kinds of specific valves are known, such as double eccentric valves and single eccentric valves such as ball valves. Double eccentric valves have an eccentric structure in which the rotation axis of the valve body is eccentric to the axis of the seat member, and the valve body and seat member do not contact when the flow path is open. , the valve body contacts only near the position where the flow path is closed (see Patent Document 1). On the other hand, in a ball valve, the valve body and the seat member are always in contact with each other, and the valve body is opened and closed while being pressed against the seat member.

Japanese Patent Application Publication No. 2015-48856

By the way, in an eccentric valve, when the valve is closed, the valve body crushes the seat member, thereby generating a repulsive force on the contact surface between the valve body and the seat member. As a result, the two come into close contact and the flow of fluid etc. is blocked. However, even though the valve is in the closed state, so-called seat leakage may occur, in which fluid or the like flows between the valve body and the seat member from upstream to downstream. Seat leakage is undesirable because it changes the amount of fluid flowing as a material and may adversely affect the quality of the product. Therefore, when the valve body is fully closed, it is required to keep the leakage amount of fluid, etc. within an allowable range.

In general, seat leakage includes seat leakage caused by foreign matter being caught between the seat member and the valve body, and seat leakage caused by seat member fatigue or wear. The former type of seat leakage is caused by solid foreign matter adhering to the contact surface between the valve body and the seat member, and is often a temporary leak if there is no permanent damage to the seat member. . On the other hand, the latter type of sheet leakage occurs due to deterioration of the sheet member over time, and once leakage occurs, it will continue to occur, so there is a risk that it will have a significant negative impact on, for example, product quality. There is.

Further, since seat leakage due to settling or wear occurs inside the valve device, it is difficult to immediately detect the occurrence from the outside. In particular, valve devices with automatic operation functions are often installed in narrow spaces where manual inspection is not possible, in remote locations, or in special atmospheric environments. Therefore, sheet leakage is often discovered after some time has elapsed from the time of occurrence, which may cause energy loss, resource loss, decrease in yield, and the like. For example, one possible method for detecting sheet leakage is to install various sensors such as a flow rate sensor or a vibration sensor, and detect it based on the output from the sensor. However, this method has problems such as the cost of installing the sensor and the difficulty in setting a threshold value for determining the occurrence of sheet leakage. Therefore, it is desired to be able to easily detect sheet leakage due to fatigue or abrasion immediately after it occurs, or to be able to predict it in advance.

The present invention has been made in view of the above circumstances, and provides an eccentric valve device that can accurately detect or predict seat leakage due to settling or wear in eccentric valves including double eccentric valves, and a control method thereof. The purpose is to provide

The eccentric valve device of the present invention is an eccentric valve device that controls blocking or opening of a flow path in piping, and the eccentric valve device includes a substantially cylindrical valve box having an opening communicating with the flow path. a ring-shaped seat member mounted around the opening in the valve box; and a ring-shaped seat member rotatably provided in the valve box and pressed against the seat member to block the flow path. a valve body that rotates the valve body, a valve drive unit that rotates the valve body, and a control unit that controls driving of the valve drive unit, and the valve body does not come into contact with the seat member when the valve is open and is not in contact with the seat member when the valve is closed. The control unit has a structure that contacts the seat member in a valve state, and the control unit includes a leakage determination unit that determines seat leakage between the seat member and the valve body based on drive parameters of the valve drive unit. This is a characteristic feature.

Further, in the eccentric valve device of the present invention, the control unit may be configured to move the valve body to a predetermined position close to the seat member in the process of rotating the valve body to change the valve open state to the closed state. The valve body includes a temporary stop portion that temporarily stops the rotation of the valve body, and the leakage determination portion determines the seat leakage after the rotation of the valve body is temporarily stopped.

In the present invention, a "proximate predetermined position" is a position where the valve body does not come into contact with the seat member, and is such that the gap between the valve body and the seat member is narrowed and foreign matter attached to the valve body and the seat member is blown away. This is a position where the flow rate of fluid, etc. can be increased. Furthermore, in the present invention, "determining sheet leakage" includes not only determination that sheet leakage has actually occurred but also determination of signs of sheet leakage.

Further, in the eccentric valve device of the present invention, the control unit includes a position determination unit that determines that the valve body has rotated to the predetermined position based on a rotation angle of the valve body, and the temporary stop unit The valve body temporarily stops rotating when the position determining section determines that the valve body has rotated to the predetermined position.

Further, in the eccentric valve device of the present invention, the temporary stop portion stops rotation of the valve body for 0.5 seconds to 2 seconds.

Further, in the eccentric valve device of the present invention, the control section includes a torque calculation section that calculates a drive torque of the valve drive section based on the drive parameter, and the leakage determination section calculates the drive torque of the valve drive section based on the drive parameter. If the determined driving torque is smaller than a predetermined threshold value, it is determined that the sheet leakage has occurred.

A control method for an eccentric valve device according to the present invention is a control method for an eccentric valve device that controls blocking or opening of a flow path in piping, wherein the eccentric valve device has an opening communicating with the flow path. a cylindrical valve box; a ring-shaped seat member mounted around the opening in the valve box; and a ring-shaped seat member rotatably provided within the valve box and pressed against the seat member. and a valve drive unit that rotates the valve body, the valve body does not contact the seat member in the valve open state, and does not contact the seat member in the valve closed state. In the process of rotating the valve body to change the valve open state to the closed state, the valve body contacts the seat member at a predetermined position close to the valve body. a step of temporarily stopping the rotation of the valve body; and a step of determining seat leakage between the seat member and the valve body based on a drive parameter of the valve drive unit after the rotation of the valve body is temporarily stopped. It is characterized by having.

As described above, according to the eccentric valve device and the control method thereof according to the present invention, seat leakage due to settling or wear can be detected or predicted with high accuracy.

1 is an explanatory diagram showing the overall schematic configuration of an eccentric valve device according to the present invention. FIG. 2 is an enlarged sectional view of the valve mechanism section of FIG. 1; It is a sectional view showing a fully open state of a valve body. It is a sectional view showing a fully closed state of a valve body. FIG. 1 is a block diagram of an eccentric valve device according to the present invention. It is a figure which shows the torque change when a valve body shifts from a fully closed state to a fully closed state. FIG. 3 is an explanatory diagram showing a state in which the valve closing operation of the valve body is temporarily stopped. 3 is a flowchart showing a processing procedure for detecting sheet leakage. It is a figure showing the relationship between calculated torque and a threshold value. It is a timing chart showing the flow when the valve body transitions from a fully open state to a fully closed state.

FIG. 1 is an explanatory diagram showing the overall schematic configuration of an eccentric valve device according to the present invention, and FIG. 2 is an enlarged sectional view of the valve mechanism section of FIG. 1. Note that FIG. 1 shows a part of the eccentric valve device as a sectional view. An eccentric valve device 1 shown in FIG. 1 is a device that is disposed in the middle of a flow path in a pipe through which fluid or the like flows, and controls blocking or opening of the flow path.

As shown in FIG. 1, the eccentric valve device 1 includes a valve mechanism section 2 having a valve body 22, a valve drive section 3 that drives the valve mechanism section 2, and a control section 4 that controls the drive of the valve drive section 3. Equipped with The valve mechanism section 2 and the valve drive section 3 are connected by a valve rod 35, and the drive of the valve drive section 3 can be transmitted to the valve mechanism section 2. The eccentric valve device 1 has a function of maintaining the posture of the valve body 22 at a fully open position, a fully closed position, or an arbitrary position (for example, a position immediately before fully closing).

The control unit 4 is mainly composed of a microcomputer including a well-known CPU, ROM, RAM, etc. Note that in FIGS. 1 and 5, the control unit 4 is shown separately from the valve drive unit 3 for convenience, but the valve drive unit 3 also has a built-in microcomputer, and the functions of the control unit 4, which will be described later, are The microcomputer of the valve drive unit 3 may have all or part of it.

The valve mechanism section 2 includes a substantially cylindrical valve box 21, a valve body 22 rotatably provided within the valve box 21, a ring-shaped seat member 23 mounted within the valve box 21, and a seat member 23. A support member 24 that supports the. The valve mechanism section 2 is installed in the middle of piping for fluid, etc., and piping (not shown) is connected to the upstream and downstream sides of the valve box 21, respectively. Fluid and the like flow in the direction of the arrow in FIG. By rotating the valve body 22 in the valve mechanism section 2, the flow path in the valve box 21 is blocked or opened, and the flow of fluid etc. from the upstream side to the downstream side can be blocked or opened.

As shown in FIG. 2, the valve box 21 has an opening 211 that communicates the upstream flow path with the downstream flow path. A step 214 is formed around the opening 211 and extends radially inward so that the inner circumferential surface of the valve box 21 is reduced in diameter, and the seat member 23 is attached to the step 214 . The seat member 23 is supported by a support member 24 inserted from the upstream end of the valve box 21 . A mounting hole 212 is formed in the upper part of the valve box 21, through which the inner circumferential surface and the outer circumferential surface pass, and into which the valve stem 35 is inserted. The mounting hole 212 is formed in a direction perpendicular to the axial direction of the valve box 21, and the valve rod 35 is rotatably inserted therein. Further, a pin groove 213 into which the pin 25 fits is formed in the lower part of the valve box 21.

Inside the valve box 21, a valve body 22 is connected to an end of a valve stem 35, and as the valve stem 35 rotates, the valve body 22 rotates. The axis of rotation of the valve stem 35 and the axis of rotation of the valve body 22 are aligned. Note that FIG. 2 shows a fully closed state in which the valve body 22 closes the opening 211.

The valve body 22 has a substantially disc-shaped valve portion 221 and support portions 222 and 223. The upstream end surface of the valve portion 221 constitutes a sealing surface, and is formed by a flat surface at the center of the disk and a curved surface at the peripheral edge of the disk. The curved surface is formed in a convex shape toward the upstream side. The support portion 222 is connected to the valve stem 35 and the support portion 223 is connected to the pin 25. The valve body 22 is made of a metal material such as stainless steel.

The seat member 23 has a hollow circular seat ring 231 and a rubber ring 232. The surface of the seat ring 231 facing the valve body 22 constitutes a sealing surface. A groove is formed on the back side of the sealing surface of the seat ring 231, and a rubber ring 232 is fitted into the groove. The seat ring 231 is made of resin such as polytetrafluoroethylene resin, for example. This resin may contain a fibrous reinforcing material such as carbon fiber or glass fiber. Further, for the rubber ring 232, for example, fluororubber such as tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), nitrile butadiene rubber (NBR), or the like can be used. In the valve closed state as shown in FIG. 2, the valve portion 221 of the valve body 22 is pressed against the sealing surface of the seat member 23 and the sealing surface of the valve body 22.

Next, the operation of the valve mechanism section 2 will be explained using FIGS. 3 and 4. 3 and 4 are partial sectional views of the valve mechanism section of FIG. 2 viewed from the valve stem side. As shown in each figure, the valve body 22 has a double eccentric structure. Specifically, the rotation axis O of the valve body 22 is eccentric by a distance Y with respect to the axis of the seat ring 231, and the rotation axis O of the valve body 22 is eccentric by a distance X with respect to the sealing surface of the seat ring 231. There is.

FIG. 3 shows the valve body 22 in a fully open state, and the valve portion 221 of the valve body 22 faces in a direction perpendicular to the flow path. At this time, the valve body 22 is not in contact with the seat member 23. From this fully open state, the valve body 22 rotates so that the valve portion 221 faces the upstream side of the flow path. The valve body 22 rotates at a rotation angle θ from 0 degrees to 90 degrees, with a fully open state being 0 degrees and a fully closed state being 90 degrees. FIG. 4 shows the valve body 22 in a fully closed state, with the valve portion 221 of the valve body 22 facing in the upstream direction of the flow path. The flow path is blocked by the valve body 22 coming into close contact with the sheet member 23. The opening and closing speed of the valve body 22 can be set as appropriate, and generally the time required from a fully open state to a fully closed state is 1 second or more.

In the fully closed state shown in FIG. 4, the seat member 23 is pressed against the valve body 22 and thereby elastically deforms. The amount by which the sheet member 23 deforms (sheet width margin) is generally about 1/500 to 1/1000 of the cross-sectional width of the sheet member 23. In the case of an eccentric valve, the seat member repeatedly deforms each time the valve body opens and closes. The seat member is scraped approximately in proportion to the number of times the valve body is opened and closed, and the amount of collapse of the seat member becomes smaller, which may eventually cause seat leakage. Even if there is a risk of sheet leakage, if there is no serious impact, the production process will continue to operate without stopping, but energy loss will occur. Furthermore, if the production process is seriously affected, the production process must be stopped immediately, resulting in a large loss.

The eccentric valve device 1 according to the present invention detects or predicts seat leakage by determining leakage based on the drive parameters of the valve drive unit when the valve body 22 transitions from the open state to the closed state. I can do it. Thereby, sheet leakage can be detected by easy means. Further, in the present invention, since the present invention is directed to seat leakage caused by seat member fatigue or wear, it is preferable to temporarily stop the valve-closing operation of the valve element in order to detect it separately from seat leakage caused by foreign matter being caught. Specifically, during a valve closing operation, the valve body is temporarily stopped just before it contacts the seat member to temporarily maintain a high flow rate of the fluid flowing between the seat member and the valve body. Then, a step is provided to blow away foreign matter adhering to each sheet surface. Thereby, it is possible to eliminate the influence of the drive parameters due to foreign matter being caught, and it is possible to detect sheet leakage due to fatigue or wear of the sheet member with higher accuracy.

FIG. 5 is a block diagram showing an example of an eccentric valve device according to the present invention. The eccentric valve device 1 includes a valve mechanism section 2, a valve drive section 3, and a control section 4, and the specific configuration of the valve mechanism section 2 is as described above. The eccentric valve device 1 also includes sensors 51, 52, and 53 that detect drive parameters, and each sensor is connected to the control unit 4. The detection results of each sensor are input to the control unit 4 at any time, and are configured to be continuously detected and stored during the opening/closing operation. The control unit 4 also has various calculation functions. In the present invention, the drive parameters are parameters indicating the drive state of the valve drive section 3, and include, for example, the motor rotation speed of the motor section 33, motor current value, motor voltage value, drive torque, and rotation angle θ. It is something that In the present invention, since the drive parameters of the valve drive unit 3 are used to detect seat leakage, separate sensors such as a flow rate sensor or a vibration sensor are not required, and seat leakage can be detected by easy means. can.

The valve drive section 3 includes a power supply circuit section 31 , a motor circuit section 32 , a motor section 33 , a reduction gear (gear box) 34 , a valve rod 35 , and a current sensor 53 . The motor circuit section 32 is connected to the power supply circuit section 31 and adjusts the current flowing through the motor section 33 based on a control signal from the control section 4 . The motor section 33 is composed of a brushless motor, and rotates the output shaft based on the current flowing from the motor circuit section 32. In the configuration of FIG. 1, the rotational speed of the main shaft is reduced by the reducer 34, and the valve stem 35 is rotated.

In FIG. 5, the control section 4 includes a position determination section 41, a temporary stop section 42, a torque calculation section 43, and a leakage determination section 44. Processes in each part are mainly executed when the valve body 22 transitions from the open state to the closed state.

The position determination unit 41 determines that the valve body 22 has rotated to a predetermined position close to the seat member 23. The close predetermined position is a position where the valve body 22 does not contact the seat member 23, and the gap between the valve body 22 and the seat member 23 is narrowed to the extent that foreign matter attached to the valve body 22 and the seat member 23 is blown away. This is a position where the flow rate of fluid, etc. can be increased. For example, this is the position where the distance d (see FIG. 7) between the sealing surface of the valve portion 221 and the sealing surface of the seat ring 231 is approximately 0.5 mm.

Specifically, position determination by the position determination unit 41 is performed based on the rotation angle θ detected by an angle sensor 52 such as an encoder. When the rotation angle θ (see FIG. 7) reaches a predetermined angle (for example, 60 degrees or 70 degrees), the position determination unit 41 determines that the valve body 22 has rotated to a predetermined position.

The temporary stop unit 42 temporarily stops the valve-closing operation of the valve body 22 when the position determination unit 41 determines that it has rotated to a predetermined position. Specifically, the supply of electric power from the motor circuit section 32 to the motor section 33 is cut off, and the drive of the valve drive section 3 is stopped. The temporary stop time is not particularly limited, and is appropriately set depending on the opening/closing speed of the valve body 22, the diameter size of the pipe, the type of fluid, etc. The pause time is, for example, 0.5 seconds to 2 seconds.

The torque calculation unit 43 calculates the drive torque of the valve drive unit 3 based on drive parameters such as the rotational speed of the motor unit 33 detected by the rotation sensor 51 and the motor current value detected by the current sensor 53. The calculation of the driving torque can be performed according to a known method.

The leakage determination section 44 determines seat leakage between the seat member 23 and the valve body 22 based on the drive parameters of the valve drive section 3 . For example, in the configuration of FIG. 5, sheet leakage is determined based on the drive torque calculated by the torque calculation unit 43 and a predetermined threshold value.

Here, the driving torque of the valve body 22 changes by about 10 times or more from the fully open state to the fully closed state. FIG. 6 shows the torque change when the rotation angle θ of the valve body 22 changes from 0 degrees (fully open state) to 90 degrees (fully closed state). FIG. 6 shows three patterns of torque changes: normal, seat leakage due to foreign matter biting, and seat leakage due to wear.

As shown in Figure 6, in each pattern, the torque is stable at a low value until the rotation angle θ is around 60 degrees, and when the rotation angle θ exceeds 60 degrees, the torque starts to increase, and the rotation angle The torque increases until θ reaches 90 degrees. Due to the structure of the double eccentric valve, the seat member 23 and the valve body 22 only come into contact near the fully closed position, and compared to, for example, a ball valve, the torque is particularly stable in an angle range up to about 60 degrees.

In the case of sheet leakage due to foreign matter being caught, the start-up is faster and the torque value is larger than in the normal case. For example, if the fluid etc. contains solid foreign matter such as powder or slurry, the foreign matter tends to adhere to each sealing surface of the valve body 22 and the seat member 23, and if the foreign matter gets between these, it may cause the valve to close. Since the valve operation becomes overloaded, the torque becomes larger than when it is normal. On the other hand, in the case of seat leakage due to wear, the torque tends to be smaller than in the normal case. For example, when the seat member becomes sagging or worn, the repulsive force of the seat member when the valve is closed is reduced in many cases, so that the torque becomes smaller than when it is normal. In this way, by considering differences in torque changes based on events, seat leakage due to fatigue or wear can be detected with higher accuracy.

Specifically, the leakage determination unit 44 determines that sheet leakage has occurred when the calculated drive torque is smaller than a predetermined threshold. The above-mentioned predetermined threshold value can be set based on a correlation between the amount of sheet leakage and the torque obtained through an experiment. In addition, as another determination method in the leakage determination unit 44, seat leakage occurs when the difference between the calculated driving torque and the past value (for example, the torque calculated at the time of the previous valve closing) exceeds a certain value. It is also possible to adopt a method of determining that For example, an average value of the past 100 times is used as the past value.

Further, in the configuration of FIG. 5, seat leakage is determined based on the drive torque calculated by the torque calculation unit 43, but in an eccentric valve device having a torque sensor capable of detecting the drive torque of the motor unit 33, the torque sensor Leakage determination can also be performed based on the drive torque detected in . Furthermore, leakage determination may be performed based on drive parameters other than drive torque. For example, since the motor current value has a substantially correlation with the driving torque of the motor unit 33, the motor current value can be used for leakage determination.

FIG. 7 shows a state in which the valve body 22 is temporarily stopped during the valve closing operation. As shown in FIG. 7, the valve body 22 is temporarily stopped at a position immediately before the seat ring 231 and the valve portion 221 come into contact. In this state, the distance d between the sealing surface of the valve portion 221 and the sealing surface of the seat ring 231 becomes smaller, so that the flow velocity of fluid etc. around the seat ring 231 increases, and foreign matter adhering to the valve portion 221 and the seat ring 231 increases. can be removed. As a result, the frictional force generated by the subsequent contact between the valve portion 221 and the seat ring 231 becomes a pure frictional force unaffected by foreign matter, so that a decrease in sealing performance due to settling or wear can be detected with high accuracy.

Next, the sheet leakage detection process of the control unit 4 during the valve closing operation will be described. This detection process is repeatedly performed at predetermined time intervals.

FIG. 8 is a flowchart showing the processing procedure for detecting sheet leakage. The process from the start to the end in FIG. 8 is repeatedly executed at predetermined time intervals. First, in step S11, it is determined whether a command to close the valve body (close command) has been input from a higher-level control device or the like. If step S11 is Yes, the process proceeds to step S12, and if step S11 is No, this process is temporarily ended.

In step S12, it is determined whether the temporary stop flag is off. As will be described later, the temporary stop flag is turned on after the valve body 22 is temporarily stopped. If step S12 is Yes, the process advances to step S13 and the motor section 33 is driven. The valve body 22 is rotated toward a fully closed state by driving the motor section 33. In step S14, drive parameters regarding the drive of the motor section 33 are acquired. Specifically, the motor current value and motor rotation speed are acquired. In subsequent step S15, drive torque is calculated based on the acquired motor current value and motor rotation speed.

In step S16, it is determined whether the drive torque is within the normal range. Specifically, it is determined whether the drive torque calculated in step S15 is smaller than a predetermined threshold value. The predetermined threshold value is appropriately set depending on the type and flow rate of the fluid flowing through the flow path. As shown in FIG. 6, the torque is generally stable at a low value until the rotation angle at which the valve body 22 contacts the seat member (for example, the rotation angle θ is 60 degrees) is exceeded. Therefore, if the torque suddenly increases and becomes equal to or higher than a predetermined threshold value, it is considered that an abnormality such as foreign object jamming has occurred. If it is determined that the drive torque is not within the normal range (No in step S16), the process proceeds to step S28 and error processing is executed. Error processing includes issuing a warning alarm and lighting a warning lamp. Note that as an error process, the drive of the motor section may be stopped to interrupt the valve closing operation.

If step S16 is Yes, the process proceeds to step S17, and it is determined whether or not the valve body 22 has rotated to a predetermined position. Specifically, it is determined whether the rotation angle θ detected by the angle sensor 52 has reached a predetermined angle. If the valve body 22 has not reached the predetermined position (No in step S17), this process is temporarily ended. In addition, in FIG. 8, if step S17 is No, a loop may be provided to repeatedly execute the processes from step S13 to step S17.

When the valve closing operation of the valve body 22 progresses and the valve body rotates to a predetermined position (step S17: Yes), the drive of the motor section 33 is stopped (step S18). Thereafter, the motor unit 33 is stopped until a predetermined time has elapsed, and after the predetermined time has elapsed (step S19: Yes), the temporary stop flag is turned on (step S20), and this process is temporarily ended. Note that the portion that executes the processing in step S17 corresponds to a position determination section, and the portion that executes the processing in steps S18 and S19 corresponds to a temporary stop section. Furthermore, a temporary stop in the present invention is not limited to a case where the operation of the valve body completely stops, but also includes a case where the operation of the valve body is decelerated to such an extent that it can be simulated that the operation of the valve body has stopped. For example, the operating speed of the valve body during deceleration is set to about 1/20 of the operating speed of the valve body before deceleration (before temporary stop).

When the temporary stop flag is turned on and step S12 is negative, the process proceeds to step S21 and the motor section 33 is driven again. This restarts the valve closing operation. In the following step S22, it is determined whether the valve body is in the fully closed position. Specifically, it is determined whether the rotation angle θ detected by the angle sensor 52 is 90 degrees. If step S22 is No, drive parameters are acquired (step S25), and drive torque is calculated (step S26). The processing in step S25 and step S26 is similar to the processing in step S14 and step S15.

In step S27, it is determined whether the drive torque is within the normal range. Specifically, the determination is made based on the drive torque calculated in step S26 and a predetermined threshold value. Here, the relationship between the calculated value and the threshold value is shown in FIG. The threshold value is set lower than the torque under normal conditions, and is usually lower than the calculated value. Although the threshold value is not particularly limited, it is set to a value that is 10% lower than the normal torque (for example, at the time of shipment). In step S27 of FIG. 8, for example, it is determined whether the drive torque calculated at each rotation angle is smaller than a predetermined threshold value at that rotation angle. If it is determined that the drive torque is smaller than the predetermined threshold (No in step S27), the process proceeds to step S28 and error handling is executed.

If it is determined that the drive torque is within the normal range (Yes in step S27), this process is temporarily terminated. Then, when the valve closing operation continues while the drive torque is within the normal range and the valve body 22 reaches the fully closed position and step S22 is affirmed, the drive of the motor section 33 is stopped (step S23) and temporarily The stop flag is turned off (step S24), and the series of processes ends. Note that the part that executes the process of step S26 corresponds to a torque calculation part, and the part that executes the process of step S27 corresponds to a leakage determination part.

Although FIG. 8 has shown the processing in the control unit 4 during the valve closing operation, the control method of the present invention is not limited to this. For example, the predetermined position determined in step S17 may be made variable depending on the flow rate, viscosity, temperature, etc. of the fluid. Specifically, the position where the valve body is temporarily stopped may be shifted toward the valve opening side as the flow rate of the fluid or the like increases, as the viscosity of the fluid or the like increases, or as the temperature of the fluid or the like decreases. Further, the temporary stop time of the valve body (step S19) may also be made variable depending on the flow rate, viscosity, temperature, etc. of the fluid. Specifically, the temporary stop time may be shifted to the side where the faster the flow rate of the fluid, the greater the viscosity of the fluid, and the lower the temperature of the fluid, the shorter the temporary stop time is. This makes it possible to suppress vibration and erosion of the valve body, etc.

In addition, in FIG. 8, when it is determined that the drive torque is not within the normal range (step S27 is No), error processing (step S28) is immediately performed, but in order to reliably eliminate the possibility of abnormal torque due to foreign matter , a cleaning operation may be performed before the error processing, and the leakage determination may be performed again based on the drive torque calculated after the cleaning operation. Examples of the cleaning operation include an operation in which the above-mentioned paused state and a state in which the valve is slightly opened from the paused state are repeated multiple times at regular intervals. The cleaning operation allows more accurate calculation of the torque generated due to friction between the valve body and the seat member. As a result, the accuracy of leak determination can be further improved.

Moreover, in FIG. 8, seat leakage was determined based on the driving torque after the valve body was temporarily stopped. That is, although a configuration has been shown in which the occurrence of seat leakage is detected using the eccentric valve device 1, it is also possible to predict seat leakage with a similar configuration. In this case, for example, by setting the threshold value used in step S27 higher than in the case of sheet leakage detection, it is possible to determine the stage immediately before sheet leakage occurs (signs of sheet leakage). Based on the determination result, the timing of sheet leakage can be predicted. Furthermore, it is also possible to determine when sheet leakage occurs from changes in the drive torque calculated at any time.

FIG. 10 is a timing chart showing the flow when the valve body 22 transitions from a fully open state to a fully closed state. In the fully open state, when a command to close the valve body is issued at time t1, the motor section is started and the valve closing operation is started. As time passes, the rotation angle θ increases. At this time, the torque remains stable at a low value. At time t2, when the valve body rotates to a predetermined position, the motor section stops and the valve closing operation is temporarily stopped. After the temporary stop time ta has elapsed, the motor section is activated and the valve closing operation is resumed (time t3). As the valve opening operation progresses and the seat member and the valve body come into contact, the torque increases. When the fully closed state is reached at time t4, the motor section stops and the valve closing operation is completed. Between time t3 and time t4, sheet leakage is determined at any time based on the drive torque.

In the above embodiment, a double eccentric valve has been described as an eccentric valve device according to the present invention, but the present invention can also be applied to an eccentric valve that exhibits the same torque change as a double eccentric valve when opening and closing the valve.

The eccentric valve device of the present invention can accurately detect or predict seat leakage due to fatigue or wear in eccentric valves including double eccentric valves installed in production process piping in production plants, so it is safe and efficient. maintenance is possible, and overall losses in the production process can be reduced. In addition, it is possible to replace the valve before seat leakage occurs, contributing to stable operation of the equipment and reducing work efficiency related to equipment maintenance and maintenance.

1: Eccentric valve device 2: Valve mechanism section 21: Valve box 211: Opening section 212: Mounting hole 213: Pin groove 214: Step section 22: Valve body 221: Valve section 222: Support section 223: Support section 23: Seat member 231: Seat ring 232: Rubber ring 24: Support member 25: Pin 3: Valve drive section 31: Power supply circuit section 32: Motor circuit section 33: Motor section 34: Reducer 35: Valve rod 4: Control section 41: Position determination Section 42: Temporary stop section 43: Torque calculation section 44: Leakage determination section 51: Rotation sensor 52: Angle sensor 53: Current sensor

Claims (5)

An eccentric valve device that controls blocking or opening of a flow path in piping,
The eccentric valve device includes a substantially cylindrical valve box having an opening communicating with the flow path, a ring-shaped seat member mounted around the opening in the valve box, and a ring-shaped seat member mounted in the valve box around the opening. a valve body that is rotatably provided and that blocks the flow path by being pressed against the seat member; a valve drive unit that rotates the valve body; and a control that controls driving of the valve drive unit. Equipped with a
The valve body has a structure that does not contact the seat member in the valve open state and contacts the seat member in the valve closed state,
The control unit includes a leakage determination unit that determines seat leakage between the seat member and the valve body based on drive parameters of the valve drive unit,
The control unit temporarily stops rotation of the valve body at a predetermined position where the valve body is close to the seat member in the process of rotating the valve body to change the valve open state to the closed valve state. It has a temporary stop part to
The eccentric valve device is characterized in that the leakage determination section determines the seat leakage after rotation of the valve body is temporarily stopped . The control unit includes a position determination unit that determines that the valve body has rotated to the predetermined position based on a rotation angle of the valve body,
The eccentric valve device according to claim 1 , wherein the temporary stop section temporarily stops the rotation of the valve body when the position determination section determines that the valve body has rotated to the predetermined position. 3. The eccentric valve device according to claim 1 , wherein the temporary stop portion stops rotation of the valve body for 0.5 seconds to 2 seconds. The control unit includes a torque calculation unit that calculates a drive torque of the valve drive unit based on the drive parameter,
Any one of claims 1 to 3 , wherein the leakage determination unit determines that the sheet leakage has occurred when the drive torque calculated by the torque calculation unit is smaller than a predetermined threshold value. The eccentric valve device according to item 1. A method for controlling an eccentric valve device that controls blocking or opening of a flow path in piping, the method comprising:
The eccentric valve device includes a substantially cylindrical valve box having an opening communicating with the flow path, a ring-shaped seat member mounted around the opening in the valve box, and a ring-shaped seat member mounted in the valve box around the opening. comprising a valve body that is rotatably provided and that blocks the flow path by being pressed against the sheet member, and a valve drive unit that rotates the valve body,
The valve body has a structure that does not contact the seat member in the valve open state and contacts the seat member in the valve closed state,
The control method includes temporarily stopping the rotation of the valve body at a predetermined position where the valve body is close to the seat member in the process of rotating the valve body to change the valve open state to the closed valve state. and a step of determining seat leakage between the seat member and the valve body based on drive parameters of the valve drive unit after the rotation of the valve body is temporarily stopped. Control method for eccentric valve device.

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