JP4776409B2 - Electric valve - Google Patents

Description

  The present invention relates to an electric valve capable of detecting a motor overload state and avoiding a failure.

  One of the causes of motor valve failure is overload. If an overload is applied to the electric valve, in the worst case, the motor coil may be burned out and the life may be significantly shortened.

  As one method for solving this problem, Patent Document 1 describes that an electric valve is provided with a valve (valve) opening / closing detection mechanism.

  In this electric valve, the controller transmits a closing signal to the electric valve. If a valve closing signal is not obtained from the opening / closing detection mechanism after a predetermined time has elapsed, the transmission of the closing signal is interrupted and switched to the opening signal, and then the closing signal is retransmitted. By doing so, the valve is automatically opened and the dust biting into the valve is washed away, and then the valve is closed, so that it is possible to prevent the trouble of leakage due to biting. In addition, since the bitten waste is washed away and the valve is closed, the motor coil can be prevented from being burned by being energized.

JP-A-6-281039

  However, the above method has a problem that it takes too much time to detect an abnormality.

  That is, the open / close detection mechanism cannot detect an abnormality and output an open signal until a sufficient time has elapsed for the valve to close.

  Therefore, there is a problem that a valve abnormality cannot be detected during the standby. As described above, when it takes a long time to detect the abnormality of the valve, there is a problem that the damage to the motor increases and the damage due to the bite leak increases.

  Here, the case where the valve is closed has been described. However, the present invention is not limited to this, and the valve may be opened depending on the use form.

  The above electric valves are for boilers, but there are other electric valves that have different opening / closing angles or have different opening / closing times depending on the purpose and application. I want to be able to respond.

  Accordingly, an object of the present invention is to prevent damage to the motor by making it possible to detect an abnormality of the electric valve in a short time, and to reduce damage caused because the valve cannot be opened or closed. It is to be able to cope with electric valves with different opening and closing times.

  In order to solve the above problems, the present invention comprises a sensor means for detecting the amount of movement of the valve, a timer means, and a memory means for measuring and storing in advance the time required for the valve to move by a predetermined amount. When the timer means starts the time from the operation of the motor that drives the valve, and the time reaches the required time stored in the memory means in advance, the amount of movement of the valve detected by the sensor means, and the memory A configuration is adopted in which a predetermined amount of movement of the valve is compared with the required time stored in the means and an abnormality is detected based on the comparison result.

  By adopting such a configuration, the memory means stores in advance a time required for the valve to move by a predetermined amount, thereby storing a reference value for detecting an abnormality for each valve. By doing so, it is possible to deal with the case where the opening / closing angle differs depending on the purpose and application, or the case where the opening / closing time differs greatly. The abnormality is detected in a short time by detecting whether or not the valve can move a predetermined amount within the stored time.

  The predetermined amount is smaller than the amount that the valve is fully closed or fully opened, and is the minimum amount of movement that is necessary for discriminating a normal valve.

  When the time of the timer means reaches the required time stored in the memory means, the movement amount per unit time calculated from the required time stored in the memory means and a predetermined movement amount by which the valve moves during the required time. In addition, the movement amount obtained by multiplying the time measured by the timer means and the movement amount detected by the sensor means are sequentially compared, and an abnormality is detected based on the comparison result.

  By adopting such a configuration, the movement amount can be calculated by multiplying the movement amount per unit time by the time measured by the timer means, and the calculated movement amount can be compared with the movement amount detected by the sensor means. Therefore, abnormality can be detected sequentially.

  At this time, the moving amount per unit time calculated from the required time stored in the memory means and the moving amount of the valve during the required time and the moving amount calculated from the time measured by the timer means are gradually reduced. It is possible to adopt a configuration in which the rate is multiplied and compared with the amount of movement detected by the sensor means.

  By adopting such a configuration, an error due to variation among valves is corrected so as not to cause an error in determination. Further, by providing a margin for the determination, it is possible to deal with electric valves having different opening / closing angles and opening / closing times.

  Moreover, the structure which set the upper limit and the minimum in the required time memorize | stored in a memory means is employable.

By adopting such a configuration, for example, when the measurement time is t1 (t << t1) seconds longer than the scheduled time t seconds, the measurement is stopped at time t seconds, and the movement amount for t seconds is measured. The upper limit of the measurement time is set with the movement amount as a predetermined movement amount. In this way, the time for detecting an abnormality is normalized and shortened. Conversely, for example, when the amount of movement of the valve reaches a predetermined amount in t0 (t0 << t) seconds shorter than t seconds, the time for detecting an abnormality is set by setting t0 seconds as the measurement time. Normalize to eliminate error factors such as start-up delay and gear backlash at start-up so that valve abnormalities can be detected without error.

  At this time, when measuring the required time to be stored in the memory means, it is possible to adopt a configuration in which a dead zone period is provided between the start of the motor and the start of measurement.

  By adopting such a configuration, it is possible to eliminate error factors such as delay at start-up and gear backlash by not performing measurement during the dead zone.

  According to the present invention configured as described above, the abnormality of the electric valve can be detected in a short time.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the electric valve of this embodiment includes an electric actuator 2 and a valve (valve element) 3.

  The electric actuator 2 includes a speed reduction mechanism 4, a motor 5, an opening degree detection sensor 6, and a control circuit 7.

  Here, the speed reduction mechanism 4 is composed of, for example, a speed reduction gear group in which spur gears are combined. The speed reduction mechanism 4 is connected to the rotation shaft of the motor 5 and transmits the rotational force of the motor 5 to the valve 3.

  The motor 5 uses an AC motor (for example, a reversible motor capable of instantaneously reversing the rotation direction) that has a large starting torque, is robust, and can be reversibly operated with a simple circuit.

  Here, the opening degree detection sensor 6 uses a potentiometer (hereinafter, the opening degree detection sensor is referred to as a potentiometer), and the potentiometer 6 is attached to an output shaft that connects the speed reduction mechanism 4 and the valve 3, for example. By connecting to a control circuit 7 to be described later, the movement amount of the valve 3 can be detected. The sensor 6 is not limited to a potentiometer, and may be of any form as long as it can detect the absolute position of the valve 3 (for example, an absolute type may be used). Absent. For example, it is possible to use a shaft encoder or the like.

  For example, the control circuit 7 includes a one-chip microcomputer 9 and a motor drive circuit 10 as shown in FIG.

  The computer 9 includes a timer circuit and a memory circuit, and performs processing based on a processing program written in the built-in memory. The computer 9 includes an I / O input / output, an oscillation circuit, an A / D converter, and the like. The A / D converter and the potentiometer 6 can be connected to input measurement values.

  The motor drive circuit 10 is a module obtained by modularizing an AC motor drive circuit. The motor drive circuit 10 includes control terminals for right rotation (CW), left rotation (CCW), and the like. By inputting a current or voltage level signal corresponding to “H” or “L”, the motor 5 can be reversibly operated.

  Note that the command input to the microcomputer 9 is provided with a data selector to select the input so that, for example, command input by current, voltage, resistance value, etc. can be dealt with.

  This embodiment is configured as described above, and this electric valve is actually installed and used after performing a preliminary measurement process in order to set a reference value for detecting an abnormality.

  As shown in FIG. 3, the preliminary measurement process measures the time required for a normal motorized valve to move a predetermined amount of movement in advance, and measures the amount of change of the potentiometer 6 with respect to the reference time for each valve 3. To do. With such a mechanism, it is possible to cope with electrically operated valves whose opening / closing angles and opening / closing times differ greatly depending on the purpose and application.

  Here, in the preliminary measurement, a time required to open (move) ¼ of the entire operation range of the valve 3 is calculated, and this is stored in the memory as a reference predicted time Tref. Therefore, the preliminary measurement (process 200: hereinafter “process” is omitted) in the flowchart of FIG. 3 is executed.

  In the preliminary measurement (200), for example, as shown in FIG. 3, the motor 5 is turned on (205) and waits for about 1 second (210). By providing the dead zone after waiting for 1 second in this way, for example, error factors caused by delays in activation, gear backlash of the speed reduction mechanism 4 at the time of activation, and the like are eliminated.

  Incidentally, here, the standby time is set to 1 second, but is not limited to this, and the standby time may be appropriately set according to the electric valve 1 from experiments and experiences.

  When the activation is successful after 1 second has elapsed, the value of 1/4 of the potentiometer 6 is set in the temporary memory QPT, the timer counter tc is set to 0 and initialized (215), and the value of the potentiometer 6 is read into the register M1. (220).

  Next, the timer counter tc is incremented by α seconds (α can be 1 second or less) (225), and the value of the potentiometer 6 at that time is set in the register M2 (230). Next, it is determined whether the timer counter tc is 5 seconds or more or less than 5 seconds (235). Since it is “low-speed response” if it is 5 seconds or longer, the predicted time Tref is set to 5 seconds as the upper limit value. At this time, since the movement amount of the potentiometer 6 does not reach ¼ of the entire operating range, the value of the register M2-register M1 is set to Qref as the amount of change of the potentiometer 6 (260), and the motor 5 is turned off. (265), and the process ends (270). In this way, the time for detecting an abnormality is normalized and shortened.

  On the other hand, if the timer counter tc is less than 5 seconds in the process 235, the value of the register M2-register M1 is compared with the QPT (240), and if not equal to the QPT, the processes 225 to 240 are repeated until they become equal. If it is equal to QPT, it is determined whether the time measured by the timer counter tc at that time is 0.75 seconds or less (245). In the case of 0.75 seconds or less, the predicted time Tref is set to 3 seconds, the value of QPT is stored in Qref, the motor 5 is turned off (265), and the process is terminated (270). By setting the lower limit of the predicted time in this way, error factors such as start delay and gear backlash at the start are eliminated, and the time for detecting an abnormality is normalized so that it can be detected without error.

  If the time measured by the timer tc is greater than 0.75 seconds in the process 245, tc → Tref, the value of QPT is stored in the Qref, the motor 5 is turned off (265), and the process ends (270). ).

  When the reference values Tref and Qref can be set for each valve 3 as described above, it can be actually installed and used. Next, the operation will be described based on the flowchart of FIG.

  When the motorized valve starts operating (300), the timer counter tc is set to 0 and initialized (305), the command input of the motorized valve is read to the register R1 (310), and the value of the potentiometer 6 is read to the register R2. (315). Here, R1 and R2 are compared (320), and if the difference is 0, the motor 5 is stopped (360), and the process returns to step 305 and waits.

  At this time, if the difference is not 0 in step 320, the motor is turned on to rotate the motorized valve to the commanded position (325), and the time counter tc is incremented by α seconds (α can be 1 second or less). (330) The current value of the potentiometer 6 is read into the register R3 (335).

  Next, abnormality is detected using the parameters Tref and Qref set in the preliminary measurement.

First, the reference value Tref and the value of the time counter tc are compared (340). If the value tc of the time counter is equal to or larger than the reference value Tref of the preliminary measurement, the decreasing rate K is set to the change amount of the potentiometer 6 predicted from the value of tc. The amount multiplied, ie
(Tc * Qref / Tref) * K
And actual change amount | R2-R3 |
Are compared (345).

Where the expression tc * Qref / Tref
Qref / Tref is obtained as shown in FIG. 5 to calculate the movement amount per unit time, and the value is multiplied by the value of the time counter tc to calculate the predicted movement amount of the potentiometer 6. Then, the predicted value and the movement amount of the potentiometer 6 are sequentially compared. By doing so, it is possible not to wait until the valve 3 is fully opened or fully closed, but to detect it immediately, so that the time required for detecting an abnormality can be shortened. In this way, it can be applied to valves having different purposes and uses and different opening and closing times.

  At this time, since the amount of movement per unit time is calculated and compared, setting an upper limit (5 seconds) and a lower limit (3 seconds) for the measurement time in the preliminary measurement makes it possible to open and close for a long time (5 seconds or more). ) The applied valve 3 detects an abnormality in a short time of 5 seconds at the upper limit. Also, if the opening and closing is extremely short (0.75 seconds), waiting for the lower limit of 3 seconds eliminates error factors caused by delays in startup, gear backlash of the speed reduction mechanism 4, etc., and causes an error. I can not.

Further, by multiplying the obtained change amount by a decreasing rate K (in this case, 0.6, for example), an error due to the variation of each valve 3 is corrected so as not to cause an error in the determination. Further, by providing a margin for the determination, it is possible to deal with electric valves having different opening / closing angles and opening / closing times.

  Then, as a result of the comparison in the process 345, if the amount of movement of the potentiometer 6 is equal to or exceeds the predicted value, there is no abnormality, so the processes 320 to 345 are repeated until the designated position is reached.

  Conversely, if the amount of movement of the potentiometer 6 is smaller than the predicted value in process 345, it is determined that there is an abnormality, the motor is stopped (350), and an error is displayed (355).

  By performing the processing as described above, as shown in the graph of FIG. 5, even when the time required to reach the target position is longer than the error detection time, the abnormality of the electric valve can be detected in a short time.

  In the first embodiment, the control circuit 7 is constituted by a logic circuit, and as shown in FIG. 6, it comprises an arithmetic unit 20, a comparator 21, a counter 22a and a counter 22b, and latch circuits M1 to M4.

  In this circuit, the 1-second counter 22a is actuated by the start signal to start the motor 5 for 1 second, and then the measurement sequence is executed.

  In the measurement sequence, the value of the potentiometer 6 at the start of measurement (output of the A / D converter) is stored in the latch M1.

  On the other hand, the latch M2 is for storing the current value of the potentiometer 6, and monitors the value of the potentiometer 6 from the start of measurement and latches the latest value.

  If 5 seconds are reached during measurement, the process is interrupted, and the amount of change of the potentiometer 6 at that time is latched (this is a case where the detection time of the abnormality is 5 seconds at the maximum, and the potentiometer 6 is moved when it moves for 5 seconds. This is because the abnormality is detected based on the amount of change in the above).

  When the upper limit value or lower limit value of the potentiometer 6 is reached within 1.75 seconds, Tref = 3 seconds and Qref = QTP (the minimum value of the error detection time is 3 seconds. This is the switching time. Is to deal with short ones).

  The values of the latches M1 and M2 are input to the sequential calculator 20. The arithmetic unit 20 calculates the difference between the two values sequentially input and inputs the difference to the comparator 21. The comparator 21 to which this difference is inputted is previously inputted with the value QPT of the potentiometer 6 whose opening is ¼, and this value is compared with the difference to determine the value of the counter 22b and the opening. Is stored in the latches M3 and M4, respectively.

  Further, an OR circuit 23 is provided between the output of the comparator 21 and the inputs of the latches M3 and M4 so that a trigger signal corresponding to the time T at which the opening degree is ¼ is input. Therefore, for example, in the case of T ≧ 5 seconds, if a trigger signal is input by the timer 22b or the like after 5 seconds from the start, the process is interrupted and the changed value (movement amount) of the potentiometer 6 at that time is input to the latch circuit. Remember. Since the value after 5 seconds can be stored in this way, an error can be determined by multiplying this value by the coefficient K described in the embodiment. Similarly, when 3 seconds ≦ T <5 seconds, T <3 seconds can be determined in the same manner.

Schematic diagram of the embodiment Block diagram of the embodiment Flow chart of embodiment Flow chart of embodiment Action explanatory diagram of the embodiment Block diagram of the first embodiment

Explanation of symbols

1 Motorized valve 3 Valve 5 Motor K Factor Tref Reference time Qref Reference travel

Claims (5)

Sensor means for detecting the amount of movement of the valve and timer means, and memory means for measuring and storing in advance the time required for the valve to move by a predetermined amount,
When the timer means starts counting from the operation of the motor that drives the valve, and the time reaches the required time previously stored in the memory means, the amount of movement of the valve detected by the sensor means and the memory means are stored. An electric valve that compares a predetermined amount of movement that the valve moves in the required time and detects an abnormality based on the comparison result.   When the time measured by the timer means reaches the required time stored in the memory means, 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. 2. The electric valve according to claim 1, wherein the movement amount obtained by multiplying the time measured by the timer means and the movement amount detected by the sensor means are sequentially compared, and an abnormality is detected based on the comparison result.   Decreasing rate to the amount of movement calculated from the amount of movement per unit time calculated from the required time stored in the memory means and the amount of movement of the valve during the required time, and the time measured by the timer means. The electric valve according to claim 2, wherein the electric valve is multiplied and compared with the movement amount detected by the sensor means.   4. The electric valve according to claim 1, wherein an upper limit and a lower limit are set for the required time to be stored in the memory means.   The electric valve according to any one of claims 1 to 4, wherein a dead zone period is provided between the start of the motor and the start of measurement when measuring the required time stored in the memory means.

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