JP7015258B2 - Condition monitoring device and condition monitoring method for solenoid valve drive unit - Google Patents

Description

The present invention relates to a condition monitoring device and a condition monitoring method for a drive unit of an electric valve drive device used in various plants such as a thermal power plant and a petrochemical factory.

In plants such as thermal power plants and petrochemical factories, many motorized valve drive devices are used to control the flow of fluids such as water and steam flowing in pipes. In such an electric valve drive device, a worm gear is adopted as a main deceleration mechanism, the worm that meshes with the worm wheel can be slid on the worm shaft, and the load torque is detected from the axial movement amount of the worm. .. When the detected load torque exceeds a preset value, measures such as an alarm and an operation stop are taken to protect the valve and the motorized valve drive device. Here, once the solenoid valve drive device is installed, it is often used for a long period of several decades.

However, when the solenoid valve drive device is used for a long period of time, it is necessary to periodically diagnose the degree of deterioration of parts and the presence or absence of abnormalities to ensure soundness. Since the set torque also changes with the passage of operating time due to wear of parts and the like, it is required to diagnose whether the actual load torque is appropriate for the set torque. Under these circumstances, various proposals have been made for methods for detecting the difference between the set torque and the actual torque and performing abnormality diagnosis, etc. for the solenoid valve drive device that has been installed in the plant and operated for several years. There is.

In the electric valve abnormality diagnostic device described in Patent Document 1, the torque switch rotary displacement sensor detects whether or not the deflection of the torque spring is increased, while the torque spring itself is detected by detecting the sagging or breakage of the torque spring. Is being diagnosed. That is, the valve rod tip portion is brought into contact with the valve rod lock mechanism to which the load cell is attached by using the housing cover mounting bolt hole. Next, the valve opening operation is performed by the electric valve drive device, and the torque switch rotation displacement sensor and the tightening force of the drive device are compared with the correlation data input to the arithmetic processing device from the data collected by the load cell to determine the deflection of the torque spring. The relationship between the generated load (the amount of sagging of the torque spring) is calculated.

In the load continuous detection device for an electric valve actuator described in Patent Document 2, the valve body is opened and closed by a tubular worm fitted to a worm shaft rotated by a motor so as to be non-rotatable and slidable in the axial direction. A strain gauge is attached to the pressure receiving piece that is orthogonal to the axial direction of the tubular worm and receives thrust based on the axial feed of the tubular worm, and the resistance of the strain gauge due to the deformation of the pressure receiving piece. The torque of the motor is detected by the change, and a plurality of strain gauges having different distances from the shaft core are attached to the deformed portion deformed by receiving the thrust based on the axial feed in the pressure receiving piece. .. As a result, the load torque is accurately detected in the bidirectional drive of the electric valve actuator.

In the torque adjusting adapter for the electric valve and the torque adjusting method using the adapter described in Patent Document 3, the valve body drive for opening and closing the valve body by using the rotational driving force of the worm to which the rotational driving force is applied is used. It is an adapter attached to the outer end surface of the valve body drive part in an electric valve provided with a spring cartridge that is compressed by a reaction force acting in the axial direction of the worm from the valve body side of the valve body drive part. A support that is movably attached to the inside of the adapter in the axial direction and supports one end side of the spring cartridge in the compression direction by its front end, and a front end position of the support in the compression direction of the spring cartridge. A changing means that can be changed from the outside of the adapter is provided. As a result, a torque adjustment adapter that enables torque adjustment of the solenoid valve to be easily performed from the outside of the solenoid valve without the work of opening the electrical component box, and a torque adjustment method using this adapter are available. Proposed.

Japanese Unexamined Patent Publication No. 2-307033 Japanese Patent Application Laid-Open No. 2003-161661 Japanese Unexamined Patent Publication No. 2007-224970

In the above-mentioned solenoid valve abnormality diagnosis device disclosed in Patent Document 1, it is necessary to remove the housing cover and attach a valve rod lock mechanism including a load cell to the relevant portion. However, the solenoid valve drive device has various structures. Many of them are equipped with a manual handle on the housing cover side for manually driving the motorized valve. In such a case, it is difficult to attach a valve rod lock mechanism including a load cell to the portion, and there is a problem that the relationship between the deflection of the torque spring and the generated load cannot be detected.

In the load continuous detection device in the electric valve actuator described in Patent Document 2, a compression spring (belleville spring) is provided only on one end side of the worm shaft, and the structure of the member to which the strain gauge is attached becomes complicated and expensive. There is a problem of becoming. That is, it is necessary to manufacture the annular rack, the pressure receiving piece, and the small diameter sleeve as an integral part, which causes a problem that the manufacturing cost is high.

In the torque adjustment method using the adjustment adapter described in Patent Document 3, it is possible to adjust the set torque of the solenoid valve drive device by using a specially manufactured adjustment adapter, but the solenoid valve drive device is used. When operating for a long period of time, there is a problem that it is not possible to monitor the state over time.

In view of the above-mentioned problems of the prior art, the present invention relates to an electric valve drive device provided with spring packs on both ends of a tubular worm, and the set torque and the like caused by wear of the drive portion caused by long-term operation are described. It is an object of the present invention to provide a condition monitoring device and a condition monitoring method for an electric valve drive unit capable of monitoring a state change.

In the present invention, a worm wheel is rotated by a tubular worm fitted to a worm shaft rotated by a motor so as to be non-rotatable and slidable in the axial direction so that the valve body can be opened and closed, and the valve body can be opened and closed at one end of the worm shaft. A thrust bearing capable of receiving a radial load and a thrust load is provided, and a radial bearing capable of receiving a radial load is provided at the other end of the worm shaft, and the outer ring of the thrust bearing is fixed in an adapter provided on the side surface of the housing. One end side elastic body is provided between one end side of the worm shaft and one end side of the tubular worm, and the one end side elasticity is provided between the other end side of the worm shaft and the other end side of the tubular worm. An elastic body on the other end having a spring characteristic different from that of the body is provided, and a torque sensor for detecting load torque from the amount of axial movement of the tubular worm is provided, and a thrust sensor for detecting thrust is provided on the side surface of the adapter. The outputs of the torque sensor and the thrust sensor are input to the control device to which the memory is connected, and the thrust value and the torque value at an arbitrary opening degree in the valve opening / closing operation are stored every time a predetermined time elapses. It is a state monitoring device of an electric valve drive unit characterized by.

Further, in the state monitoring device of the motorized valve drive unit, the load torque detected by the torque sensor is compared with the thrust detected by the thrust sensor , and the state is monitored from the change over time. This is a method for monitoring the condition of the motorized valve drive unit.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a state monitoring device and a state monitoring method for a solenoid valve drive unit that can detect a change over time such as a set torque even if the solenoid valve drive device has elastic bodies on both ends of the tubular worm. be able to.

It is a partial cross-sectional view which shows the drive part of the electric valve drive device which concerns on this invention. It is a block diagram about the state monitoring apparatus which concerns on this invention. It is a characteristic diagram which shows the relationship between the load torque and thrust when the valve is opened and closed by the electric valve drive device which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a driving portion of the motorized valve driving device 1 according to the present invention, which is orthogonal to the stem 2 of the valve and includes a shaft core of the worm shaft 3.

The motor 4 is attached to the side surface of the housing 6 as a valve actuator main body via the motor adapter 5. In many cases, a three-phase induction motor having excellent reliability such as durability is used for the motor 4.

A worm gear 7 is built in the housing 6 as a main deceleration mechanism. When the worm shaft 3 and the worm 8 are rotated by the motor 4, the worm wheel 9 that meshes with the worm 8 rotates, and the rotation of the worm wheel 9 drives the stem 2 of the valve. FIG. 1 shows an example of driving a sluice valve, in which the stem 2 of the sluice valve is driven via a drive sleeve 11 and a stem nut 12 provided inside the worm wheel 9.

The axis of the motor shaft 13 is offset from the axis of the worm shaft 3, and is arranged on the front side of the paper in the example of FIG. The reason for such an arrangement is that when the motor shaft 13 is directly connected to the worm shaft 3, the rotation speed of the worm shaft 3 is too fast, and the speed is reduced in the previous stage between the motor shaft 13 and the worm shaft 3. Specifically, the motor shaft 13 is provided with a pinion (not shown), and the worm shaft 3 is provided with a gear 14 that meshes with the pinion.

A cylindrical worm 8 that meshes with the worm wheel 9 is fitted in a substantially central portion of the worm shaft 3 so as to be slidable in the axial direction. Specifically, it is fitted using the key 15. Therefore, the tubular worm 8 rotates integrally with the worm shaft 3, but is slidable in the axial direction of the worm shaft 3. The above is a general configuration of the motorized valve drive device as a conventional technique, and is not a characteristic configuration of the present invention.

In the present invention, a plurality of disc springs 16 and 17 (hereinafter referred to as spring packs) are incorporated on both ends of the tubular worm 8. In the conventional solenoid valve drive device shown in Patent Documents 1 to 3, the spring pack is arranged only on the opposite side of the tubular worm, whereas in the present invention, the spring packs 16 and 17 are both ends of the tubular worm 8. It differs from the prior art in that it is placed separately on the side.

The reason for this configuration is as follows. (1) Since the inner dimension of the housing 6 is restricted by the size of the large-diameter worm wheel 9, a certain amount of space is inevitable between the inner wall surface of the housing 6 and both end faces of the tubular worm 8. Occurs. In such a structure, if the spring packs 16 and 17 are arranged on both ends of the tubular worm 8, space efficiency is improved as a whole, and a compact solenoid valve drive device 1 can be realized. (2) The torque characteristics required for opening and closing the valve are generally different in the opening direction and the closing direction, but when the spring packs 16 and 17 are arranged separately on one end side and the other end side of the tubular worm 8. It can be a spring pack with different spring characteristics. For example, a spring pack having a large spring constant in the open direction as compared with the closed direction and given a large pressurization can be used. (3) In order to realize a compact and inexpensive solenoid valve drive device, there is an electric valve drive device that does not have a spring pack, but the spring can reduce the impact force generated when a foreign substance is caught in the valve. It is effective to have a pack.

The worm shaft 3 incorporates a tubular worm 8 and spring packs 16 and 17 on both ends thereof, and further includes bearings 18 and 19. That is, a thrust bearing 18 capable of receiving a radial load and a thrust load is provided on one end side (anti-motor side) of the tubular worm 8, and a radial load capable of receiving only a radial load is provided on the other end side (motor side) of the worm shaft 3. Bearing 19 is provided.

Specifically, the configuration of one end side of the tubular worm 8 incorporated in the worm shaft 3 will be described specifically. On one end side of the worm shaft 3, a sleeve 21, a spacer 22, a spring pack 16, a hollow shaft 23, a thrust bearing 18, The end plate 24 and the locknut 25 are sequentially incorporated, and these parts are fixed to one end side of the worm shaft 3 by the locknut 25.

Next, the configuration of the other end side of the tubular worm 8 incorporated in the worm shaft 3 will be specifically described. On the other end side of the worm shaft 3, a sleeve 21, a thrust collar 26, a spring pack 17, and a spacer 27 will be described. , Radial bearing 19, spacer 28, and locknut 29 are incorporated in this order, and these parts are fixed to the other end side of the worm shaft 3 by the locknut 29. Further, a gear 14 is incorporated in the shaft end portion of the worm shaft 3 on the outer side of the lock nut 29.

The adapter 31 is attached to the side surface of the housing 6 opposite to the side surface to which the motor 4 is attached, and the outer ring of the thrust bearing 18 provided on one end side of the worm shaft 3 is fixed in the hole of the adapter 31. .. That is, the outer ring of the thrust bearing 31 is fixed in the hole of the adapter 31 by attaching the end cap 33 to the end face of the adapter 31 using the fastening bolt 32. On the other hand, the outer ring of the radial bearing 19 provided on the other end side of the worm shaft 3 is inserted into the hole of the housing 6, but the outer ring of the radial bearing 19 is axially fixed without being fixed in the axial direction. It is a movable mating. Therefore, the radial bearing 19 bears only the radial load and cannot bear the thrust load.

An electric / electronic component storage unit 34 and a cover 35 are provided on the other side surface of the housing 6, and the electric / electronic component storage unit 34 has an opening sensor 36 and a cylinder that detect the opening degree of the valve from the rotation amount of the worm wheel 9. A torque sensor 37 that detects load torque from the amount of axial movement of the worm 8 and a state monitoring board 38 are housed in the worm 8.

The opening sensor 36 takes out the rotation amount of the worm wheel 9 by a reduction gear train (not shown) and uses it as a valve opening signal. By combining with a potentiometer, an opening signal as analog information can be obtained. Further, as the opening degree sensor 36, an absolute type rotary encoder capable of directly obtaining a digital signal from the rotation amount of the worm wheel 9 can also be used.

The torque sensor 37 obtains a torque signal from the amount of movement in which the tubular worm 8 slides in the axial direction due to the reaction force of the load torque acting on the worm wheel 9. Specifically, the amount of movement of the tubular worm 8 is detected as a rotation angle via the swing lever 39. A torque signal as analog information can be obtained by combining with a potentiometer.

The strain gauge as the thrust sensor 41 is attached to the outer surface of the annular portion of the adapter 31 and detects the axial strain of the annular portion as a resistance change of the strain gauge 41. The signal line 42 from the strain gauge 41 is connected to the condition monitoring board 38 provided in the electrical / electronic component storage unit 34.

The opening sensor 36, the torque sensor 37, and the thrust sensor 41 described above have been widely used in the motorized valve drive device, and are not sensors peculiar to the present invention.

As shown in FIG. 2, in addition to the signal from the thrust sensor 41, the signal of the torque sensor 37 and the signal of the opening degree sensor 36 are connected to the condition monitoring board 38. The signal from the thrust sensor 41 is connected to the control device 44 via the amplifier 42 and the A / D converter 43. The signal of the torque sensor 37 and the signal of the opening degree sensor 36 are connected to the control device 44 via the A / D converter 43.

The control device 44 is provided with a CPU, and a memory 45 as a storage medium and a relay 46 responsible for external signal output are connected to the control device. As will be described later, the memory 45 stores the thrust value and the torque value at an arbitrary opening degree in the valve opening / closing operation every time a predetermined time elapses. The length of the predetermined time is set individually at the site in consideration of the valve operation frequency, but about half a year to one year is sufficient.

The relay 46 supplies a contact for driving the alarm device 47, and is used, for example, to provide alarm information when the set torque drops to a certain extent compared to the initial set value.

Next, a method for monitoring the state of the motorized valve drive device according to the present invention will be described. In FIG. 1, when the worm wheel 9 is rotated clockwise to open the valve, a reaction force in the right direction corresponding to the load torque of the worm wheel 9 is generated in the tubular worm 8. However, since a predetermined pressure is applied to the spring pack 16, the tubular worm 8 does not move to the right with a reaction force equal to or less than the pressure, and maintains the initial position. When the load torque increases and the reaction force exceeds the applied pressure, the tubular worm 8 moves to the right. The amount of movement is the position where the magnitude of the reaction force and the urging force due to the compression of the spring pack 16 are balanced. The load torque is detected by the torque sensor 37 in response to the movement of the cylindrical worm 8. In such an opening operation, the reaction force in the right direction received by the tubular worm 8 is sequentially transmitted to the spacer 22, the spring pack 16, the hollow shaft 23, the end plate 24, the locknut 25, and the thrust bearing 18, and further, the thrust bearing 18 It acts as a tensile force on the adapter 31 via the outer ring, the end cap 33, and the fastening bolt 32. As a result, the strain gauge 41 attached to the outer surface of the annular portion of the adapter 31 is stretched, and is detected as a resistance change of the strain gauge 41.

Next, in FIG. 1, when the worm wheel 9 is rotated counterclockwise to close the valve, a reaction force in the left direction corresponding to the load torque of the worm wheel 9 is generated in the tubular worm 8. However, as in the case of the opening operation, since a predetermined pressure is applied to the spring pack 17, the tubular worm 8 does not move with a reaction force equal to or less than the pressure, and maintains the initial position. When the load torque increases and the reaction force exceeds the applied pressure, the tubular worm 8 moves to the left. The amount of movement is at a position where the magnitude of the reaction force and the urging force due to the compression of the spring pack 17 are balanced. The load torque is detected by the torque sensor 37 in response to the movement of the cylindrical worm 8. In such a closing operation, the reaction force in the left direction received by the tubular worm 8 is sequentially transmitted to the thrust collar 26, the spring pack 17, the spacer 27, the radial bearing 19, the spacer 28, and the locknut 29, and is screwed with the locknut 29. It is transmitted to the other end side of the combined worm shaft 3. Then, on one end side of the worm shaft 3, it acts as a compressive force on the adapter 31 via the locknut 25, the end plate 24, and the thrust bearing 18. As a result, the strain gauge 41 attached to the outer surface of the annular portion of the adapter 31 is compressed, and is detected as a resistance change of the strain gauge 41.

As described above, when the valve is opened, a tensile force acts on the strain gauge 41 attached to the outer surface of the annular portion of the adapter 31, and when the valve is closed, the strain gauge 41 is used. A compressive force acts, and in any case, the thrust as a reaction force acting on the tubular worm 8 can be detected as a resistance change of the strain gauge 41.

FIG. 3 is a characteristic diagram showing the relationship between the torque detected by the torque sensor 37 and the thrust detected by the thrust sensor 41 when the valve is opened and closed. The first quadrant is the characteristic when the operation is open, and the third quadrant is the characteristic when the operation is closed. The characteristic lines a and c show the initial characteristics when the motorized valve drive device 1 is installed in the plant, and the characteristic lines b and d show the characteristics after several years of operation. Actually, since the spring constants of the disc springs constituting the spring packs 16 and 17 have non-linearity, each characteristic line is not a straight line, but in FIG. 3, it is shown as a straight line for simplification.

First, the characteristics of the first quadrant when the valve is opened will be described. In the initial characteristics, when the motor 4 is driven to open the valve while the valve body does not have a torque seat on the valve seat, a reaction force in the right direction acts on the cylindrical worm 8, but this reaction force is The tubular worm 8 does not move because it is small and smaller than the applied pressure F0 applied to the spring pack 16. Therefore, the torque detected by the torque sensor 37 remains zero. On the other hand, the reaction force in the right direction acting on the tubular worm 8 is transmitted to the adapter 31 via the spring pack 16 on one end side, the thrust bearing 18, etc., acts as a tensile force on the strain gauge 41, and thrusts in the right direction. Is detected as.

Next, when the load torque increases and the reaction force exceeds the applied pressure F0, the tubular worm 8 moves to the right, and the torque sensor 37 detects the torque along the characteristic line a. Assuming that the preset torque for protecting the valve and the motorized valve drive device 1 from overload is T1, the thrust detected by the thrust sensor 37 when the torque reaches T1 is F1.

By the way, the amount of wear of mechanical parts such as spring packs increases with the accumulation of operating time, and the spring constant also changes due to sagging or the like. Initially, the characteristics shown by the characteristic line a may change to the characteristics shown by the characteristic line b after several years of operation. Then, even if the set torque is initially set to T1, the thrust that actually acts after several years will decrease from F1 to F2. In other words, even if the torque T1 is detected by the torque sensor 37, the actual load torque is less than T1, which leads to a torque shortage.

The characteristics of the third quadrant when the valve is closed are the same as those described for the first quadrant. Only the torque and thrust directions are different from the first quadrant. That is, in the initial characteristic c, when the motor 4 is driven to close the valve while the valve body does not have a torque seat in the valve box, a reaction force in the left direction acts on the cylindrical worm 8. Since the reaction force is small and smaller than the applied pressure F3 applied to the spring pack 17, the tubular worm 8 does not move. Therefore, the torque detected by the torque sensor 37 remains zero. On the other hand, the reaction force in the left direction acting on the tubular worm 8 is transmitted to the adapter 31 via the spring pack 17 or the like on the other end side, acts as a compressive force on the strain gauge 41, and is detected as a thrust in the left direction. To.

Next, when the load torque increases and the reaction force exceeds the applied pressure F3, the tubular worm 8 moves to the left, and the torque sensor 37 detects the torque along the characteristic line c. Assuming that the preset torque for protecting the valve and the motorized valve drive device 1 from overload is T2, the thrust detected by the thrust sensor 37 when the torque reaches T2 is F4.

Further, after several years, the thrust that actually acts will decrease from F4 to F5, and even if the torque T2 is detected by the torque sensor 37, the actual load torque will be less than T2, and the torque will be reduced. It will lead to a shortage.

Therefore, in the present invention, in order to detect a decrease in the set torque after operating the motorized valve drive device 1 for several years, the torque value and the thrust value as initial data are stored in a memory at an arbitrary opening degree of the valve opening / closing operation. In addition to being stored in the memory 45, the torque value and the thrust value at the same opening degree are stored in the memory 45 every time a predetermined time elapses. Then, in the control device 44, the thrust data detected after several years of operation is compared with the initial data, and when the data drops to a certain extent, the alarm signal is relayed and output.

The torque preset in order to protect the arbitrary opening from overload may be set to the opening corresponding to T1 or T2, but the torque must be set to the opening corresponding to T1 or T2. It is possible to detect a torque drop even at an arbitrary opening degree.

Although the present invention has been described above based on the examples, the present invention is not limited to the above-mentioned examples and can be applied in various embodiments. For example, in the above-described embodiment, the embodiment in which the sluice valve is used as the test valve has been described, but the present invention is not limited to the sluice valve, and can be applied to other types of valves such as ball valves.

Further, in the above description, a torque sensor that detects the movement amount of the tubular worm via a swing lever is used, but instead of the swing lever, the rotation angle is detected via a rack and a pinion. You can also use things.

The state monitoring device for the solenoid valve drive unit according to the present invention can be applied to the solenoid valve drive device installed in piping or the like of various plants, and the method for monitoring the condition of the solenoid valve drive unit is to drive the solenoid valve drive device. It can be used for component deterioration evaluation and abnormality diagnosis.

1 Solenoid valve drive 3 Worm shaft 4 Motor 6 Housing 8 Cylindrical worm 9 Warm wheel
16 One-sided elastic body (disc spring, spring pack)
17 Elastic body on the other end (belleville spring, spring pack)
18 Thrust bearing
19 Radial bearing
37 Torque sensor
41 Thrust sensor (strain gauge)

Claims (2)

The worm wheel is rotated by a tubular worm fitted to the worm shaft that is rotated by a motor so that it cannot rotate and is slidable in the axial direction, and the valve body can be opened and closed.
One end of the worm shaft is provided with a thrust bearing capable of receiving a radial load and a thrust load, and the other end of the worm shaft is provided with a radial bearing capable of receiving a radial load.
The outer ring of the thrust bearing is fixed in the adapter provided on the side surface of the housing.
One end side elastic body is provided between one end side of the worm shaft and one end side of the tubular worm, and the one end side is provided between the other end side of the worm shaft and the other end side of the tubular worm. An elastic body on the other end, which has spring characteristics different from that of the elastic body, is provided.
A torque sensor that detects load torque from the amount of axial movement of the tubular worm is provided, and a thrust sensor that detects thrust is provided on the side surface of the adapter.
The outputs of the torque sensor and the thrust sensor are input to the control device to which the memory is connected, and the thrust value and the torque value at an arbitrary opening degree in the valve opening / closing operation are stored every time a predetermined time elapses. A featured electric valve drive unit condition monitoring device. The state monitoring device for the motorized valve drive unit according to claim 1 is characterized in that the load torque detected by the torque sensor is compared with the thrust detected by the thrust sensor , and the state is monitored from their changes over time. A method for monitoring the condition of the motorized valve drive unit.

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