JP6338265B2 - Electric actuator for valves with biting detection function - Google Patents

Description

  The present invention relates to an electric actuator for a valve with a biting detection function.

  If foreign matter is contained in the fluid flowing in the piping system, the foreign matter mixed in the fluid when the valve provided in the piping system is opened and closed causes the valve body to bite in the fluid passage part in the valve. Sometimes. When such foreign matter is caught in the valve, the valve body stops in the middle of the opening / closing operation and the valve cannot be brought into a desired opening / closing state, so that the flow rate cannot be controlled. Overcurrent may flow through the coil of the motor that drives the coil, causing the coil to burn out.

  In the sewerage system using rainwater, which has been attracting attention recently, it is impossible to completely remove trash in the rainwater that is the source of water. Therefore, there is a possibility that such foreign matter biting occurs in the valves used in the piping system. It is expensive and it is necessary to take measures.

  2. Description of the Related Art Conventionally, there has been proposed a technique related to an electric actuator for a valve having a biting prevention function that detects biting by various methods and automatically excludes biting foreign matters in the flow direction of the piping system.

  As such an electric actuator, Patent Document 1 discloses a bypass in which a reverse rotation timer is activated and a reverse rotation operation is performed for a certain period of time when a foreign object is caught in the valve body and the timer and the motor are energized for a specified opening / closing time of the valve. After the circuit is formed, the motor repeats the reversing operation and then repeats the repetitive operation for a certain period of time, and after the foreign matter is discharged by the repetitive operation of the normal rotation and reversing, the opening or closing is predetermined. An electric valve with a foreign matter biting prevention mechanism that stops at a predetermined position has been proposed.

  Further, Patent Document 2 discloses that when a valve attached to an output shaft of an actuator bites a foreign object, an excessive torque generated on the output shaft is displaced by a worm shaft that transmits rotation of the motor to the output shaft. There has been proposed an automatic control system for a motor-operated valve that detects and removes foreign matter inside the valve body by the pressure of a fluid by reversely operating the motor-operated valve.

  Further, in Patent Document 3, when the current flowing through the motor being closed is detected by the motor current detecting means, and an overcurrent (lock current) due to a foreign object is detected, the motor is reversely rotated to open the valve body. After a certain angle is returned in the direction, when a sufficient amount of time has passed for the released foreign object to come off the valve body, the motor is rotated forward and moved in the valve closing direction, and when overcurrent due to overload is detected again, the motor is reversed. Thus, there has been proposed a motor-operated valve that repeats a discharging operation of rotating the motor forward and moving it in the valve closing direction a plurality of times after returning the valve body by a certain angle in the valve opening direction.

Japanese Patent Laid-Open No. 2-72278 JP-A-5-106754 JP 2012-229735 A Japanese Patent No. 4776409

  However, in the electric valve described in Patent Document 1, even if foreign matter is caught during the opening and closing operation of the valve body, the energization to the motor is continued until the predetermined opening and closing time elapses, and the biting state. Therefore, the possibility of damaging the valve body and actuator of the valve has not been solved. Also, the forward and reverse rotations of the motor are repeated until the foreign matter is discharged, so if the foreign matter cannot be discharged by this operation, the biting state continues for a long time, and the valve In addition to the possibility of damaging the valve body and actuator, there is a possibility that fluid control cannot be performed normally.

  In the automatic control system of the motor-operated valve described in Patent Document 2, it is known that the number of operations increases and the worm gear and worm wheel wear, and the axial play of the worm gear increases. There is a problem that hysteresis occurs and cannot be accurately detected when excessive torque is generated. In addition, when detecting the torque in the respective directions of the fully open side and the fully closed side, there is a problem that the structure of the detection unit becomes complicated.

  When the motor-operated valve described in Patent Document 3 is used to open and close the butterfly valve, in particular, a sudden torque increase caused by a closing operation near the fully closed state when the disc is closed (when the disc is seated) is bitten. There is a risk of erroneous detection and occurrence of malfunction.

In the electric valve described in Patent Document 4, when the time measured by the timer means reaches the required time stored in the memory means in advance, the valve movement amount is detected by the sensor means and the required time stored in the memory means. Is compared with a predetermined amount of movement, and an abnormality is detected based on the comparison result. After reaching the required time, the required time stored in the memory means and the predetermined time at which the valve moves at the required time. The movement amount obtained by multiplying the movement amount per unit time calculated from the movement amount of the timer by the time measured by the timer means and the movement amount detected by the sensor means are sequentially compared, and an abnormality is determined based on the comparison result. Detected.
Therefore, after the operating time of the motor reaches the required time stored in the memory means, it is possible to immediately detect the occurrence of abnormality without waiting for the valve to reach the target position. The required time is calculated by calculating the time required for the valve to move 1/4 of the entire operating range, and is used as the reference predicted time, or the lower limit value of this predicted time is 3 seconds and the upper limit value is 5 seconds. If an abnormality such as biting occurs before the operating time of the motor reaches this estimated time, the occurrence of the abnormality cannot be detected for at least 3 seconds. There is a risk of damaging the motor and valves due to excessive loads due to.
In addition, after reaching the required time stored in the memory means, a timer is set to the movement amount per unit time calculated from the required time stored in the memory means and the predetermined movement amount at which the valve moves during the required time. The movement amount obtained by multiplying the time count of the means and the movement amount detected by the sensor means are sequentially compared. In a valve having the characteristic of slowing down the movement of the body, the calculated movement amount per unit time differs greatly between the vicinity of the fully closed position and other positions. Due to differences in valve opening position and direction of operation when measuring the amount of movement, the relevance as a criterion for determining the amount of movement obtained by multiplying the amount of movement per unit time by the time measured by the timer means is large. It becomes different.

  The present invention has been developed in order to solve the above-mentioned problems, and the object of the present invention is to temporarily change the pressure or flow velocity of the fluid or the characteristics of the valve regardless of the operation direction of the valve. Without erroneously detecting the occurrence of biting of the motor torque, it is possible to detect the foreign matter accurately and immediately even immediately after the start of the motor operation. Foreign matter discharge operation is performed automatically. When foreign matter cannot be discharged, operation is stopped to prevent damage to valves and actuators, and an external biting alarm can be issued and required. It is an object to provide an electric actuator for a valve with a biting detection function that can be used in combination with a simple valve.

To achieve the above object, the invention according to claim 1, to the extent that can be detected accurately biting foreign materials, the type of valve, in view of the size and the like of the size and the actuator during opening and closing of the valve, divided divided section the set, a threshold table is an operation amount prediction value of the valve is previously stored in the data memory, obtains the threshold of operation of the valve in each divided section based on the valve threshold table which is previously stored in the data memory, on the other hand, as to measure the amount of operation of the valve in the divided sections each, comparing the the amount of operation of the valve threshold, to detect a chewing write Mino abnormality of foreign substance to the divided section for each of the comparison result This is an electric actuator for a valve with a biting detection function.

In the invention according to claim 2, when an abnormality is detected, the motor is temporarily turned off to stop the operation of the valve, and then operates in the reverse direction within a predetermined range, and then operates in the forward direction while performing the division. by measuring the amount of operation of the valve for each section with a wobbling oPERATION which successively compared with the threshold value, when an abnormality has been eliminated continues to operate in the positive direction, repeating the swinging operation when the abnormality is not resolved This is an electric actuator for a valve with a biting detection function that determines that an error has occurred and the operation of the entire apparatus is stopped when an abnormality is not resolved even if the oscillation operation is performed a preset number of times.

According to a third aspect of the invention, during the valve opening / closing operation, the motor is intermittently energized for each of the divided sections, and when the motor is de-energized, the amount of operation of the valve in the section is measured to check for foreign matter biting. a detection function with electric actuator for valve narrowing only engage you detect a write Mino abnormal.

According to a fourth aspect of the present invention, when an abnormality is detected, the motor is operated in the reverse direction for a time that is an integral multiple of the divided section, and then the motor is operated in the forward direction for a time that is an integral multiple of the divided section. a detection function with electric actuator valve for the dynamic operation narrowing seen line cormorant mesh.

  According to the first aspect of the present invention, during the opening / closing operation of the valve, a divided section divided by a constant time interval is provided in the range from the vicinity of the fully closed to the fully open, and the valve operation amount (valve of the valve) in that section is provided for each divided section. Rotation angle etc.) is measured, and the measured operation amount and the predicted operation amount (threshold value) of the valve set in advance according to the valve opening characteristic (valve angle etc.) for each of the divided sections, Since the threshold value belonging to the divided section in which the valve operation amount is measured is sequentially compared, when a foreign object is caught in the valve regardless of the valve operation direction, the valve moves to the target operation position ( Abnormality can be detected immediately for each divided section without waiting for the time to reach the fully closed position or fully open position.

  In addition, the operating speed of the valve often changes depending on the position (opening degree, etc.) of the valve body. By setting the amount of movement corresponding to the position as a threshold value for each divided section, for example, as with a butterfly valve. Even if the amount of movement suddenly decreases due to an increase in stem torque due to the valve body riding on the seat near the closed position, it is bitten by taking into account the behavior specific to the valve type without judging it as abnormal. It is possible to determine occurrence and the like, and it is possible to quickly detect an abnormality while reducing erroneous detection.

  According to the second aspect of the present invention, once the abnormality is detected, the operation of the valve is stopped once, so that an excessive load increase due to biting can be prevented, and damage to the valve and the motor can be prevented. In addition, after the valve stops operating, the valve position is returned to a certain range and re-operated (oscillating operation) to eliminate the possibility of foreign matter being caught and allow foreign matter to flow out automatically in the downstream direction. Can be increased.

Even during forward operation after reverse operation in swinging operation when an abnormality is detected, the valve operation amount in each divided section is measured for each divided section, and this measured operation amount and the divided operation belong to that divided section Since the comparison with the threshold value is sequentially performed, it can be detected in a very short time whether or not the biting has been eliminated. Therefore, it is possible to limit the time during which an excessive torque is applied to the valve, motor, gear mechanism, etc. to an extremely short time and prevent damage.
In addition, if the abnormal biting is eliminated by the reverse operation during the swing operation, the valve operation in the forward direction is continued as it is, so the bite can be eliminated with the minimum number of swing operations. Can do. Furthermore, if an abnormality is detected even after a predetermined number of peristaltic operations, it is determined as an error and the operation of the entire device is stopped. Can immediately know that is in a state that cannot be performed normally.

  According to the third aspect of the invention, the motor is intermittently energized for each divided section, and when the energization to the motor is OFF, that is, the valve operating amount is measured for each divided section at the timing when the motor torque does not act and Since the comparison with the threshold value in the divided section is performed, if a foreign object is caught, the bite is detected immediately without any load applied to the valve or the motor, and the motor is not energized again. Since the operation of the valve is stopped, damage to the valve and the motor can be further prevented.

  According to the invention of claim 4, when the occurrence of an abnormality such as biting is detected, the motor is energized for a time that is an integral multiple of the time of the divided section, and the swinging operation that operates in the opposite direction is effective. It is possible to eliminate biting of foreign matter. If the abnormality is not resolved even after a predetermined number of swinging operations, it is possible to prevent the valve and the motor from being overloaded and damaged due to biting by stopping the operation of the entire apparatus.

It is a block diagram of a configuration of an embodiment of an electric actuator for a valve with a biting detection function in the present invention. It is a figure explaining the basic composition of a central type butterfly valve. (A) It is a figure which shows typically the relationship between the operating time and valve opening degree when a center type valve | bulb operate | moves from a fully open position to a fully closed position. (B) It is a figure which shows the operation | movement principle of the biting detection function of the electric actuator for valves with a biting detection function in this invention. (A) It is a figure which shows the relationship between the stem angle position of a butterfly valve, and stem torque. (B) It is a figure which shows the relationship between the operating time and operating angle of a butterfly valve. It is a figure explaining the intermittent energization driving | running state of the motor of the electric actuator for valves with a biting detection function in the present invention. It is a figure explaining the rocking | fluctuation driving | operation of the electric actuator for valves with a biting detection function in the present invention. It is a figure explaining the action | operation flow of the electric actuator for valves with a biting detection function in this invention. It is a figure explaining the operation | movement flow following FIG. It is a figure explaining the operation | movement flow following FIG.

Hereinafter, an embodiment of a valve electric actuator with a biting detection function (hereinafter simply referred to as “valve electric actuator”) according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a configuration block diagram of an embodiment of an electric actuator for a valve. As shown in FIG. 1, the valve electric actuator 1 is attached to the upper portion of the valve 2 by being directly connected to the stem 4 of the valve body 3, is supplied with an external power supply 5, and is operated by the operation panel 6 to operate the valve 2. We are opening and closing.

  In the figure, the electric actuator for valve 1 is engaged based on a signal from the drive mechanism 11, an operation sensor mechanism 12 that recognizes the operation state of the valve body 3 based on the angular position of the stem 4, and the signal from the operation sensor mechanism 12. A control circuit 13 for detecting the occurrence of a clogging and controlling the operation of the drive mechanism 11, an operation function setting unit 14 for setting an operation condition of the actuator in the control circuit 13, and a valve opening / closing operation in advance. Based on the result, the self-learning setting unit 15 used for storing the valve opening / closing speed and the stem torque value for each valve operating position during normal operation in the memory, and the valve operation signal input from the operation panel 6 Based on the input / output interface circuit 16 that transmits to the control circuit 13 and the control signal from the control circuit 13, the drive mechanism 11 is electrically connected. The Supplying motor drive circuit 17, and a power circuit 18 for generating a DC power required from the power supplied to the control circuit 13 and the motor driving circuit 17 from the external power supply 5.

  The drive mechanism 11 outputs a motor 21, a gear reduction mechanism 22 that reduces the rotation of the motor 21 by combining a plurality of gears, and the rotation of the motor 21 decelerated by the gear reduction mechanism 22 to the outside of the actuator. An output shaft 23 is used. The rotational power of the motor 21 is transmitted to the gear reduction mechanism 22, and torque is transmitted to the stem 4 of the valve 2 via the output shaft 23, and the valve body 3 of the valve 2 is rotated via the stem 4 to rotate the valve 2. Can be opened and closed. The motor 21 can be an alternating current (AC) asynchronous motor or a direct current (DC) motor, and a direct current motor is used in this embodiment. The gear reduction mechanism 22 is free to use any reduction method as long as it has a required reduction ratio. In this embodiment, the motor is intermittently energized for each divided section, and the motor is turned off. In order to detect abnormalities such as foreign matter biting by measuring the amount of operation of the valve in the section, the output shaft 23 is used by using a cyclone speed reducer with a high meshing rate of the speed reducing mechanism and almost no backlash. In this way, the play is minimized, and almost no detection error occurs.

  The operation sensor mechanism 12 is provided on the control shaft 24 provided coaxially with the output shaft 23 above the output shaft 23 of the drive mechanism 11, and the valve body 3 of the valve 2 reaches the fully open position or the fully closed position. The main limit switches 25a and 25b for shutting off the power supply to the motor 21 and holding the valve body 3 in the fully open position or the fully closed position, and the valve body 3 of the valve 2 provided on the control shaft 24 are fully opened. The angle limit position of the stem shaft 4 of the valve body 3 is measured by measuring the rotation angle of the control shaft 24 and the auxiliary limit switches 26a and 26b that issue a signal to inform the control mechanism 11 that the position or fully closed position has been reached. The rotation angle sensor 27 to detect is comprised. The two main limit switches 25a and 25b and the two auxiliary limit switches 26a and 26b are attached to the control shaft 24 with a phase difference of 90 degrees between the main limit switches and between the auxiliary limit switches. The fully open and fully closed state of the body 3 can be detected.

  Since the control shaft 24, the output shaft 23, and the stem 4 are fixed so as to have the same rotation axis, the angular position of the stem 4 can be detected by measuring the angular position of the control shaft 24. . In the present embodiment, a potentiometer is used as the rotation angle sensor, but a rotary encoder can also be used. When a rotary encoder is used, valve stem angle information can be obtained with a digital signal by using a digital counter or a decoding circuit instead of an A / D converter described later.

  The control circuit 13 includes a data memory (EEPROM: Electrically Erasable Programmable Read-Only Memory) 28 storing a valve operation amount predicted value (threshold value) table for each type of valve, and an analog signal from the rotation angle sensor 27 as a digital signal. An A / D converter 29 for converting to a CPU, a CPU 30 for detecting the occurrence of biting of foreign matter and controlling the drive mechanism 11, and measuring the time elapsed from the start of the operation of the motor 21 to provide an operation reference for the CPU 30 And a timer counter 31 that performs the operation.

Hereinafter, a foreign object biting detection method performed by the CPU 30 will be described in detail.
If the valve driven by the electric motor is trapped by foreign matter and the stem torque increases, naturally the load torque of the electric motor also increases. However, when an AC asynchronous motor or DC motor is used as the electric motor Has a characteristic that the rotational speed of the electric motor decreases as the load torque of the electric motor increases. For this reason, when a foreign object is caught in an electric valve using an AC asynchronous motor or a DC motor, the stem rotation speed decreases due to an increase in stem torque, and a delay occurs in the valve opening and closing time. The detection method of foreign object biting of the electric actuator for valve in the present invention utilizes this “torque-opening / closing time characteristic (valve opening characteristic)”.

Here, the range from the vicinity of the fully closed to the fully open in the present invention means a range from the vicinity of the fully closed to the fully open, and a range from the fully open to the vicinity of the fully closed, especially the central butterfly. This range is important for the valve. That is, as shown in FIG. 2, the central butterfly valve 32 has a short cylindrical rubber seat ring 34 mounted on the inner periphery of a short cylindrical body 33, and upper and lower stems are mounted on the inner periphery of the rubber sheet ring 34. A disc-shaped disc 37 is opened and closed via 35 and 36. In this case, the upper and lower boss portions 38 and 39 of the disc 37 are always in contact with the upper and lower portions of the rubber sheet ring 34 from fully closed to fully open. For example, in the operation range from fully open to fully closed of the disc 37, the disc 37 Since the outer peripheral surface 40 of the disc 37 is in sliding contact with the rubber sheet ring 34 from the upper and lower portions toward the center portion, the torque of the upper and lower stems 35 and 36 tends to increase. On the other hand, in the operating range from fully closed to fully open, the torque of the upper and lower stems 35 and 36 tends to be smaller than in the operating range from fully open to fully closed. Therefore, the disc operating speed of the central butterfly valve tends to change depending on the angular position of the disc (valve element).

  FIG. 3A schematically shows the relationship between the operation time and the valve opening when the central butterfly valve operates from the fully open position to the fully closed position. As shown in the figure, even if a constant voltage is applied to the motor, the valve operating speed (stem rotational speed) varies depending on the valve opening position as described above, and is not always constant. Now, when the divided sections 42 are set at regular time intervals from the moment when power is supplied to the motor, and the valve operating speed is measured, the valve operating speed (degrees / second) in each divided section 42 can be obtained. Then, when the valve operating speed (degrees / second) in each divided section 42 is multiplied by a fixed time interval (second) in which the divided section 42 is set, the valve operation amount (degree) in the divided section can be obtained. it can.

  The valve operation amount for each divided section 42 obtained in this way is based on the measurement result in a normal state, that is, the maximum value of the operation amount of the valve under the use conditions. In actual use of the valve, it is expected that the amount of operation will not be reached due to various conditions. Therefore, it is not appropriate to use this value as a judgment criterion as it is. Therefore, considering the safety factor in order to consider various effects in the actual environment, the valve operation amount prediction obtained by dividing the valve operation amount for each division obtained in advance by the safety factor (a numerical value of 1 or more) Set as a value (threshold).

  In FIG. 3B, this threshold value 43 is represented by a continuous line. In addition, what is indicated by a columnar graph for each divided section 42 in this drawing is the valve operation amount 44 in the divided section actually measured. As shown in the figure, when the valve operation amount 44 in each divided section 42 exceeds the threshold value 43, it is determined that the valve is operating normally without occurrence of an abnormality such as a foreign object biting. be able to.

  As described above, the foreign object biting detection method of the electric actuator for valves in the present invention, which is determined by comparing the valve operation amount 44 for each divided section 42 with the threshold value 43 belonging to the divided section, is described in the above-described “opening degree− This is particularly effective when used for a central butterfly valve having a stem characteristic (valve opening characteristic).

  FIG. 4 (a) shows an example of the relationship between the valve opening degree and the stem torque value when the central butterfly valve is opened and closed. However, it is difficult to distinguish between a sudden increase in stem torque near the fully closed position and an increase in stem torque due to biting. A threshold value is set according to the valve opening, and the valve operation amount is compared with the threshold value for each divided section, so the “opening-stem characteristics (valve opening characteristics)” of the valve Abnormalities can be detected accurately without being affected.

  FIG. 4 (b) shows an example of the relationship between the valve operating time and the valve operating angle (stem angle) when opening and closing the central butterfly valve. Since the relationship is not linear, even if the amount of valve operation until a certain amount of time elapses from the fully closed position to determine the average amount of operation per unit operating time, the valve operation near the fully open position is based on that value. If the angle is predicted, there is a disadvantage that the error becomes very large. On the other hand, in the method for detecting foreign matter biting of the electric actuator for valves in the present invention, since the determination is made by comparing the valve operation amount with the threshold value for each divided section, an error occurs in the predicted value of the valve opening. It is impossible to detect an abnormality accurately.

Next, an example of a data table stored in the data memory 28 is shown in Table 1, and a method of creating this data table and a method of setting a threshold value for each divided section will be described.
In creating Table 1, the stem torque (N · m) and the operation speed (at 25 points obtained by dividing the stem angle into 24 at equal intervals from 0 degrees to 90 degrees by operating in the environment where the valve is actually used. (Degree / second) is measured, and a value obtained by dividing the operation speed (degree / second) by a safety factor of 1.2 is defined as an operation speed threshold (degree / second). The data table is stored in the data memory 28, and the threshold value (degree) of the valve operation amount in each divided section is obtained by multiplying the operation speed threshold (degree / second) in the CPU 30 by the time interval when the divided section is set. Seeking.
In order to calculate the threshold value (degree) of the valve operation amount in the CPU 30, when the operation speed threshold value is read from the data table, for example, in the case of the fully closed → fully open direction, the stem angle is changed from the angle division 0 to 1. In some cases, 2.56 (degrees / second) is read, and in the case of the angle sections 1 and 2, 2.54 (degrees / second) is read.
In addition, the above measurement was performed not only in the fully closed → fully open direction but also in the fully open → fully closed direction, and Table 1 was created from the results.

  In this example, the stem angle was divided into 24 from 0 degree to 90 degrees to acquire data, and the division interval was set with a fixed time interval of 400 milliseconds, and Table 1 was created. However, how accurate the detection can be by setting the time interval of the divided sections depends on the valve type, size, actuator size, etc. It is necessary to set these values appropriately.

  Further, the CPU 30 controls the power supplied to the motor 21 via the motor drive circuit 17, but performs intermittent energization operation of the motor 21 based on a signal from the timer counter 31. That is, as shown in FIG. 5, each divided section 42 is divided into energization time 45 and measurement time 46, power is supplied to the motor 21 within the energization time 45, and the valve operation amount 44 in the divided section is The measurement and the comparison / determination with the threshold value are performed within the measurement time 46 when the power supply to the motor 21 is not performed. In this example, the ratio of the energization time to the measurement time was 3: 1, the energization time was set to 300 msec, and the measurement time was set to 100 msec.

  As described above, the measurement of the valve operation amount and the comparison / determination with the threshold value are performed at intervals of about 400 milliseconds, so that when a foreign object is caught, an abnormality is detected immediately (in practice, instantaneously). be able to. This kind of quick response to abnormality detection has the characteristic that the edge of the disc rides on the seal sequentially during the process of moving the disc from the fully open position to the fully closed position, like a central butterfly valve, and foreign matter is always easily caught. It is suitable for the valve which has.

  In addition, since power is not supplied to the motor 21, an abnormality is detected at a timing when the torque does not act. Therefore, when an abnormality is detected, the motor 21 is in a state where no load is applied to the valve or the motor. Since the operation of the valve can be stopped by stopping the re-power supply to the valve, it is possible to prevent the valve and the motor from being damaged.

  When the CPU 30 detects that a foreign object is caught, the CPU 21 temporarily turns off the power of the motor 21 without restarting the power supply to the motor 21 even if the time counting by the timer counter 31 proceeds. After stopping the operation, it operates in the reverse direction within a predetermined range set by the method to be described later, and then performs the swinging operation that operates in the forward direction, so that the caught foreign matter automatically flows out in the downstream direction. aim.

  In FIG. 6, the operation of the valve after detecting the foreign object biting will be described. Now, since the valve operation amount 48 in the n-th divided section 47 exceeds the threshold value 43, the biting is not detected. Since the valve operation amount 50 in the next n + 1-th divided section 49 does not exceed the threshold value 43, biting is detected. Then, the CPU 30 operates the time valve in the reverse direction by an integral multiple of the division interval set by a method described later. Here, if this integer multiple is three times, the valve operates in the reverse direction by the time of the section 54 including the n + 2 divided section 51, the n + 3 divided section 52, and the n + 4 divided section 53. However, the operation is reversed by the operation amount 55, but at this time, the comparison with the threshold value 43 is not performed. When the operation of the valve in the reverse direction is completed, the CPU 30 operates the valve in the forward direction in the (n + 5) th divided section 56. Since the valve operation amount 57 in this divided section 56 does not exceed the threshold value 43, the bite is detected, and the valve starts to operate in the second reverse direction. The n + 6th divided section 58 and the n + 7th divided section 59, the operation is performed in the reverse direction for the time of the section 61 including the (n + 8) th divided section 60. After the reverse operation is performed by the operation amount 62, the operation is shifted to the forward operation in the (n + 9) th divided section 63. When the foreign matter bite is eliminated by the reverse operation, the valve operation amount 64 in the divided section 63 exceeds the threshold value 43, so it is determined that the bite has been eliminated, and the forward operation is continued in the next divided section. .

  As described above, in the electric actuator for a valve according to the present invention, the amount of valve operation is measured for each divided section and is sequentially compared with a threshold value even in the forward motion of the swing motion. It can be immediately detected in the first divided section after shifting to the forward direction operation that the foreign matter has not been eliminated in the backward direction operation, and the measurement time 46 at the timing when the power supply to the motor 21 is not performed. Since the abnormality is detected, the re-power supply to the motor 21 can be stopped and the operation of the valve can be stopped in a state where no load is applied to the valve or the motor, so that the valve or the motor is prevented from being damaged. can do.

  Also, in the swing operation after detecting the biting, if the biting is not resolved by the reverse direction operation, an abnormality is detected in the first divided section after shifting to the forward direction operation, and further from the opening position. Since the reverse direction operation is performed by an integral multiple of the divided section, the valve operation amount (shift amount) in the reverse direction sequentially increases each time the number of swinging operations increases, so that it is easy to eliminate foreign matter biting.

  If the bite is not resolved even after the predetermined number of swinging operations, the CPU 30 stops the power supply to the motor 21 and outputs an error alarm to the operation panel 6 via the input interface 16 so that the foreign matter is not applied to the valve. Is warned that there is a problem in controlling the fluid due to the occurrence of the bite and that the foreign matter needs to be removed by disassembling the valve, so that the necessary response can be taken quickly.

The operation setting unit 14 includes a divided section internal ratio setting unit 65, an integer multiple setting unit 66, a swing number setting unit 67, and a fully closed full open non-detection setting unit 68. In the present embodiment, a dip switch is used as the operation setting unit 14, and as shown in Table 2, setting of the divisional section internal ratio setting, integer multiple setting, number of swings setting, fully closed full open non-detection setting, biting The necessity of detection was assigned to 10 switches B0 to B9. As will be described later, the operation setting can be easily performed by setting each switch to the position of “1 (ON)” or “0 (OFF)”, and the setting state can be easily confirmed visually. .
The operation function setting unit 14 may use a dip switch having a large number of switches, thereby changing the time interval for setting the division interval.

  The ratio between the energization time and the measurement time in the divided section can be set by the B0 and B1 switches of the dip switches. By setting the B0 and B1 switches as shown in Table 3, the ratio between the energization time and the measurement time in the divided section can be specified in the range from 2: 1 to 5: 1.

  It is possible to set by the B2 and B3 switches of the dip switch how many times the time interval of the divided section is operated in the reverse direction during the swing operation. By setting the B2 and B3 switches as shown in Table 4, it is possible to specify the time for which the valve is operated in reverse in a range from 2 to 5 times the divided section.

  The number of times that the swing operation is performed can be set by the B4 and B5 switches of the dip switch. By setting the B4 and B5 switches as shown in Table 5, the number of times the valve is operated in reverse can be specified in the range of 2 to 5 times.

  Depending on the type of the valve, if the valve is operated from the fully open position or the fully open position, the operation state may not be constant because the influence of interference between the valve body and the seal member is large. When such a valve is targeted, there is a problem in that the biting detection becomes inaccurate if the biting detection is performed in which the valve operation amount is measured and compared with the threshold value in an operating range where the operation state is not constant. Arise. Therefore, it is accepted that the biting detection is slightly delayed, and the biting detection mask area shown in FIG. 3 can be set in such a divided section within the operation range that the valve biting detection is not performed. did. As shown in Table 6, this area can be set from 0 to 5 degrees by setting the B6 to B8 switches, either in the fully open position or the fully closed position, or in both the fully open position and the fully closed position. The operating range from 0 degrees to 10 degrees can be set.

  Whether or not foreign object biting is detected can be set by the B9 switch of the dip switch. Set to “1” when foreign object biting detection is necessary and set to “0” when not necessary. As described above, the electric actuator for a valve according to the present invention can be used by selecting a required function by a simple operation at a place where the biting detection is necessary and an unnecessary place.

  The self-learning setting unit 15 operates the valve in an environmental state where it is actually used in advance, and stores a data table of the valve body operation speed and stem torque for each valve body position during normal operation based on the operation result. It is an operation part for memorizing it.

  The input interface unit 16 has a function of transmitting an input from the operation panel 6 to the CPU 30 when the valve is fully opened or fully closed, and transmitting an error signal indicating occurrence of biting from the CPU 30 to the operation panel 6 side.

  The motor drive circuit 17 has a function of receiving a signal from the CPU 30 and supplying electric power to the motor 21 so that the valve element rotates in a predetermined direction.

  The power supply circuit 18 is supplied with electric power (AC or DC) from the external power supply 5 and supplies electric power to the control circuit 13 and the motor drive circuit 17. When the external power supply 5 is AC, control is performed after conversion to DC. This is supplied to the circuit 13.

  Hereinafter, a method of detecting the biting of the valve by the electric actuator for valve in the present invention will be described. 7 to 9 are flowcharts of control for detecting the biting of the valve by the valve electric module according to the present invention.

  First, in step 101, the actuator is initially set. In this step, the number of oscillations in the count register is set to zero. In the next step 102, the number of swings set by the operation setting unit 14 and the reverse operation time setting multiple (a value that is an integer multiple multiplied by the set time interval of the divided section) are read. In step 103, a valve opening / closing input signal is read. In step 104, it is determined whether or not an input signal is input. In step 105, it is determined whether or not the input signal is a fully open input.

  If the input signal is a fully closed input, the flow proceeds to step 106R, and if the input signal is a fully open input, the flow proceeds to step 106L.

  If the valve is in the fully closed state, it is determined in step 106 whether the fully open side auxiliary limit switch is OFF (whether the valve is closed). If it is OFF, the valve is closed and the flow shifts to C. If ON, the valve is in the fully open position, so the process returns to step 102 and waits for the next open / close input signal.

  After determining that the fully closed input is input in step 105, it is determined in step 106R whether the fully closed side auxiliary limit switch is OFF (whether the valve has not reached the fully closed position). Since the valve has not yet reached the fully closed position, the motor is energized in Step 107R, and the valve operates in the fully closed direction. If the fully closed auxiliary limit switch is ON, the valve has reached the fully closed position, and the flow returns to step 102.

  For a valve operating in the fully closed direction (positive direction), it is determined in step 108R whether the fully open side auxiliary limit switch is OFF (whether the valve has not reached the fully open position). Therefore, the process proceeds to step 109R, and the valve operation amount in the divided section is measured in step 109R. If it is ON, the valve is in the fully open position, and the process returns to step 107R.

  In step 110R, a threshold value belonging to the divided section corresponding to the divided section measured in step 109R is read from the data table, and the valve operation amount is compared with the threshold value. If the valve operation amount exceeds the threshold value, the number of swings is set to zero in step 111R. If the valve operation amount has not reached the threshold value, the routine proceeds to step 116R.

  In step 112R, it is determined whether or not the fully closed auxiliary limit switch is OFF (whether the valve has not reached the fully closed position). If OFF, the valve has not yet reached the fully closed position. Returning, the measurement of the valve operation amount in the next divided section is repeated. If the fully closed auxiliary limit switch is ON, the valve has reached the fully closed position, so whether or not the fully closed main limit switch is ON in step 113R (whether power supply to the motor is stopped). If it is ON, since the motor is still operating in the direction to close the valve, this determination is repeated until it is turned OFF. If it is determined to be OFF, the energization of the motor in the closing direction is stopped in step 114R, and the valve stops at the fully closed position.

  Thereafter, after the interval at step 115R, the process returns to step 102.

  If it is determined in step 110R that the valve operation amount has not reached the threshold value, it is determined that foreign matter is caught, and in order to perform the swing operation, power supply to the motor is stopped and closed in step 116R. The rotation in the direction is stopped, and 1 is added to the count of the number of oscillations in step 117R.

  After the interval at step 118R, power supply is started so that the motor rotates in the opening direction (reverse direction) at step 119R, the reverse operation time of the valve is measured at step 120R, and the reverse direction of the valve at step 121R. It is determined whether or not the operation time exceeds the set operation time set by reading the backward operation multiple in step 102. If the operation time in the reverse direction of the valve exceeds the set operation time, power supply to the motor in the opening direction is stopped in step 122R, and the valve stops at a position shifted from the biting position in the closing direction. . If the reverse operation time of the valve does not exceed the set operation time, the process returns to step 119R, and the process proceeds to the reverse method until it is determined in step 121R that the operation time in the reverse direction of the valve has exceeded the set operation time. The operation continues.

  After stopping power supply to the valve in step 122R, after the interval in step 123R, it is determined in step 124R whether or not the number of swing operations exceeds the set swing number read in step 102. . If the number of swinging operations does not exceed the set number of swings, the process returns to Step 107R to supply power to the motor in the fully closed direction (forward direction), measure the valve operation amount in Step 109R, Step 110R The valve operation amount measured in step 1 is compared with the threshold value. When the foreign object bite has been eliminated by the previous operation of the valve in the reverse direction, the process proceeds to step 110R, the operation in the fully closed direction (forward direction) is continued, and the bite has not been eliminated. Shifts to step 116R and continues the rocking operation.

  If it is determined in step 124R that the number of swinging operations has exceeded the set number of swings, the process proceeds to step 125, and an error display indicating the occurrence of biting is displayed on the operation panel via the input interface 16.

  The flow chart of the control when the fully closed input is input to the valve in the fully open position has been described above. However, when the fully open input is input to the valve in the fully closed position, the process proceeds from step 105 to step 106L. However, in the subsequent flow, there is only a difference whether the valve is operated to the closed side or the open side, and the other flows are the case where the fully closed input is input to the valve in the fully opened position described above. It is the same except that the operation direction of the valve is reversed. If it is determined in step 124L that the number of swinging operations has exceeded the set number of swings, the process proceeds to step 125, and an error display indicating the occurrence of biting is displayed on the operation panel via the input interface 16. .

  As described above, the valve electric actuator according to the present invention provides a divided section divided at a short time interval in the range from the vicinity of the fully closed to the fully opened during the valve opening / closing operation, and the electric actuator is provided for each divided section. The valve operation amount in the section is measured, and this measured operation amount is sequentially compared with the predicted valve operation amount (threshold value) set in advance according to the valve opening characteristic for each of the divided sections, and the comparison is made. Since abnormalities such as foreign object biting are detected for each divided section from the results, when foreign object biting occurs, the abnormality can be detected in an extremely short time (in practice, instantaneously).

  Also, each divided section is divided into energization time and measurement time, the motor is intermittently energized, and the detection of biting is performed at the timing when the motor torque does not act.If an abnormality is detected, the valve or motor is Since the operation of the valve can be stopped in a state where no load is applied, it is possible to prevent the valve and the motor from being damaged due to overload.

  In addition to this, in the valve swing operation that is performed to automatically discharge foreign matter when biting occurs, if the biting of foreign matter has not been eliminated by reverse direction operation, the reverse direction operation is changed to the forward direction operation. It is possible to detect that the biting has not been eliminated in the divided section immediately after shifting to, and the next swinging motion can be started immediately. Further, in the next swinging motion, the amount of movement of the valve in the reverse direction is increased as compared with the previous swinging motion, so that it is possible to easily remove the bitten foreign matter.

  Furthermore, the electric actuator for a valve in the present invention uses an existing auxiliary limit switch and a potentiometer, and it is not necessary to add a new mechanical mechanism at all, and an external appearance can be obtained by adding a dip switch inside the actuator housing. Since it has a biting prevention function while keeping the dimensions the same as before, it can be easily attached to an existing piping system, and its utility value is very large.

  Although the above description has been made on a rotary type valve in which the valve body rotates, it can also be applied to a linear movement type valve by devising a configuration inside the operation sensor mechanism.

1 Electric actuator for valves
2 Valve 3 Valve body 4 Stem 5 External power supply 6 Operation panel 11 Drive mechanism 12 Actuation sensor mechanism 13 Control circuit 14 Operation function setting unit 15 Self-learning setting unit 16 Input / output interface unit 42 Dividing section 43 Predicted value of valve operation amount (threshold value) )
45 Power-on time 46 Measurement time

Claims (4)

In order to accurately detect foreign object biting, the divided section is set when opening and closing the valve in consideration of the valve type, size, actuator size, etc., and a threshold table that is the predicted amount of valve operation is set. Preliminarily stored in the data memory, based on the valve threshold table stored in advance in the data memory, the threshold of the valve operation amount in each divided section is obtained, while measuring the valve operation amount in each divided section, An electric actuator for a valve with a biting detection function , which compares the operation amount of the valve with the threshold value, and detects an abnormal biting of foreign matter for each divided section from the comparison result.   When an abnormality is detected, the motor is turned off once and the valve operation is stopped.Then, the valve operates in the reverse direction within a predetermined range and then operates in the forward direction. Swing operation is performed to measure and sequentially compare with the threshold value. When the abnormality is resolved, the operation in the positive direction is continued, and when the abnormality is not resolved, the rocking operation is repeated to preset the rocking operation. 2. The electric actuator for a valve with a biting detection function according to claim 1, wherein when the abnormality is not solved even after the number of times, the error is determined and the operation of the entire apparatus is stopped.   During the valve opening / closing operation, the motor is intermittently energized for each of the divided sections, and when the power to the motor is OFF, the amount of operation of the valve in that section is measured to detect foreign matter biting abnormalities. The electric actuator for valves with a biting detection function according to claim 1 or 2.   The method according to claim 3, wherein when an abnormality is detected, the motor is operated in the reverse direction for a time that is an integral multiple of the divided section, and then the swing operation is performed in which the motor is operated in the forward direction for a time that is an integral multiple of the divided section. The electric actuator for valves with the biting detection function described.

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