JP2739512B2 - Stop position abnormality detection mechanism of electric actuator for valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial Application Field) The present invention is to stop an electric actuator for opening and closing a valve body such as a rotary opening / closing valve such as a ball valve and a butterfly valve by an electric mechanism. The present invention relates to a position abnormality detection mechanism.

(Prior art) A non-commutator motor such as a pulse motor is generally used for this type of electric actuator, and a control circuit includes:
Generally, a digital circuit is used.

As a configuration for stopping the motor at a predetermined position, for example, a position of a motor rotor or an output shaft is detected, and control is performed based on the detected position.

In the proportional control, a general servo loop control for stopping at a command position is generally performed by a feedback signal from a position sensor attached to an actuator shaft.

(Problems to be Solved by the Invention) As described above, when the conventional motor control method is used for, for example, an electric actuator used for opening and closing a valve, there are the following problems.

That is, in an electric actuator such as a valve, a foreign substance or the like may be clogged in a valve controlled by the electric actuator. In such a case, when a conventionally known control system is used as it is, when the foreign matter is clogged, the valve movement stops and the motor output shaft stops.

At this time, in the conventional control system, there is a problem that the feedback signal of the clogged position is continuously output and the motor burns out.

It is also conceivable to stop the motor by using an ordinary digital circuit to stop the motor by measuring the number of revolutions of the motor with an adder or the like. Is currently not applicable.

In view of the above problems, the present invention is a stop position abnormality detection mechanism for an electric actuator that solves the conventional problem, comparing both a rotation direction signal obtained from a detection signal to be fed back and a control command direction signal obtained from a deviation signal, It is an object of the present invention to provide a mechanism for detecting a stop position abnormality of an electric actuator for preventing a motor from being burned out by alarming or stopping the motor when a discrepancy occurs in the result.

Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention provides an electric actuator which feeds back a detection signal of a motor and a control output position thereof and controls the motor based on a deviation from a command input. A pulse motor is used as the motor, and a detection signal for feedback of the valve opening position as a control output is branched, and one is input to a differentiating circuit to obtain a rotation direction signal of forward rotation, reverse rotation, and stop, and another is instructed. A control command direction signal for forward rotation and reverse rotation is obtained by comparing with an input signal, and an abnormal biting state generated in the valve is detected by comparing the two.

In this case, when the valve biting abnormality detection circuit detects that the actuator has stopped during control,
In order to eliminate the cause of the abnormality, the actuator is reversely rotated for a predetermined time to open the valve, or the normal / reverse rotation is repeated to remove the bite of the cause of the abnormality, and thereafter, the rotation is returned to the normal rotation.

In order to detect a detection signal of the valve opening position, a slider that slides on the surface of the conductive plastic is provided on the valve opening / closing operation shaft, and a change in the sliding position is used as a valve opening detection signal.

(Operation) In the stop position abnormality detecting mechanism of the electric actuator according to the present invention, a detection signal to be fed back from the output shaft of the motor is branched, and one of the signals is input to a differentiating circuit, and any one of forward rotation, reverse rotation, and stop By obtaining such a rotation direction signal and comparing the other with a command input signal, a forward / reverse control command direction signal is obtained.

If the feedback signal does not match the command input signal, a deviation signal is output and both the rotation direction signal and the control command direction signal are output until the feedback signal matches.

In the process of matching the feedback signal and the command input signal, the control command direction signal is output, but if the rotation direction signal is not output, an alarm signal is output from the digital circuit and the motor drive oscillator stops outputting. Then, a stop signal is output to the motor driver, which acts to stop the rotation of the motor.

Therefore, for example, in the case of a valve, if something gets stuck before the valve is fully closed, the motor load is quickly stopped or a warning is issued to an operator assuming that there is some abnormality in the motor load, and the valve is issued. This has an advantageous effect on the maintenance management of the machine that uses.

If there is no bite in the valve and the command input signal matches the feedback signal, the output of the deviation signal stops, and the rotation of the motor stops.

At this time, the output of both the control command direction signal and the rotation direction signal is stopped, so that an operation such as an alarm circuit is prevented.

Also, to detect the detection signal of the circuit position, a slider provided on the motor output shaft is slidably provided on the conductive plastic surface of the actuator case, and the change in resistance due to the change in the sliding position is used as the detection signal. Therefore, due to the durability of the conductive plastic, an accurate feedback signal can be obtained when the valve or the like is used repeatedly, and it works to more reliably grasp the abnormal operation.

In addition, a stopper that restricts the output shaft only in the rotation range of the manual opening / closing member fixed to the output shaft of the electric actuator is provided in the actuator case, so that the output shaft of the electric actuator can rotate only in a certain range. Has become.

Therefore, a reference point required when a pulse motor is used as a power source of the electric actuator acts so that one rotation limit point of the output shaft can be used as a reference. By visually checking the position of the manual opening / closing member fixed to the shaft, it is possible to determine the abnormal operation of the valve, and it is also possible to manually cancel the abnormal stop position.

(Example) Hereinafter, the present invention will be described with an example based on the drawings.

1 to 3 are views of a partial electric actuator of an actuator for a valve.

Here, a commutatorless motor 1 such as a pulse motor is built in an actuator case 4 made of an appropriate material. The output shaft 2 of the motor 1 projects outside the actuator case 4 and is used for rotating a valve or the like (not shown).

A slider 3 is provided inside the actuator case 4 of the output shaft 2 so that the surface of the conductive plastic 5 provided on the inner surface of the actuator case 4 can be slid.

The sliding position between the slider 3 and the conductive plastic 5 is used as a feedback signal.

In this embodiment, the slider 3 has one end, and the other end is connected to an end of the conductive plastic 5.

This connection point is provided, for example, on the conductive plastic 5 on the side where the resistance value of the slider 3 becomes minimum when the output shaft 2 is fully opened, and is used as the maximum resistance value when the output shaft 2 is fully closed.

In connection using this feedback signal, the slider 3 can be connected to the output shaft 2 having one of the above-mentioned grounds, for example, the ground, and the other side of the conductive plastic 5 can be used as a feedback signal.

Note that the conductive plastic 5 is the actuator case 4
Is made of a conductive material such as a metal, it is provided insulated therefrom.

The reason why the conductive plastic 5 is used is that, in consideration of the durability of the conductive plastic 5, it is optimal for a device that is repeatedly used such as a valve. In addition, a feedback signal obtained by a conventional potentiometer or the like is used. When the potentiometer is obtained, the operation of the potentiometer is performed via a gear or the like on the output shaft, so that the device also has a problem that the device becomes large-scale.

On the other hand, on the outside of the actuator case 4, a stopper 7 is provided, which also serves as a positioning when the manual opening / closing member 6 fixed to the output shaft 2 is fully opened and fully closed.

The range in which the rotation is limited by the stopper portion 7 differs depending on the type of valve, and is set to a range that substantially matches the valve opening / closing angle. For example, about 90 when opening and closing at right angles
A stopper part 7 is provided so that it can be opened and closed at any time.

It is desirable that the manual opening / closing member 6 has such an external appearance that it can be manually operated from the outside when the electric actuator is mounted on a valve or the like.

 Next, the operation system of the motor 1 will be described.

In detecting the rotational position of the motor 1, a detection signal obtained by changing the sliding position of the slider 3 on the conductive plastic 5 is fed back to the deviation comparator 8. The deviation comparator 8 outputs a deviation between the command input signal and the detection signal, amplifies the signal by an amplifier 9, and outputs a drive signal of the motor 1 by a driver 15 via a control command direction comparator 11 and a digital comparison circuit 13. After the conversion, the motor 1 is rotated.

On the other hand, after the detection signal is input to the differentiating circuit 10 and amplified, the rotation direction of the motor is input to the digital comparison circuit 13 via the rotation direction comparator 12.

Although not described in the present embodiment, the digital comparison circuit 13 compares two signals of the control direction signal obtained from the control command direction comparator 11 and the rotation direction signal obtained from the rotation direction comparator 12, and for example, A signal for stopping the motor 1 or a signal for rotating the motor 1 in reverse for a predetermined time or repeating forward / reverse rotation is issued to the driver 15.

Next, the operation of the embodiment in the case where the motor 1 provided in the actuator case 4 is rotated to close the valve will be described.

When the manual opening / closing member 6 shown in FIGS. 1 and 3 is at the position of the solid line (broken line in FIG. 3), the valve is fully opened, and when it is at the position of the dotted line (dotted line in FIG. 3), the valve is fully open. The output shaft 2 rotates so as to rotate the manual opening / closing member 6 so as to close.

At this time, the manual opening / closing member 6 is positioned by the stopper portions 7 at the time of full opening / closing, and is configured so as not to be able to rotate any more. Accordingly, the rotation range of the output shaft 2 to which the manual opening / closing member 6 is fixed is similarly limited, and by positioning the manual opening / closing member 6 against the stopper portion 7, the zero point based on the rotation of the motor 1 can be positioned. Can be done.

Further, by visually observing the position of the manual opening / closing member 6, it is possible to determine the opening degree of the valve, and it can be used as a manual opening / closing member that is manually used at the time of an original power failure or the like.

Now, when the motor 1 rotates, a slider 3 is provided inside the actuator case 4 of the output shaft 2, and rotates similarly to the rotation of the manual opening / closing member 6 as shown in FIG. Then, the surface of the conductive plastic 5 provided on the inner surface of the actuator case 4 slides. A feedback signal is obtained by connecting the slider 3 to one end and the other end to the conductive plastic 5, and the sliding point is set so that the resistance value of the slider 3 at the fully closed position of the output shaft 2 is the maximum. Value.
The output of the deviation comparator 8 is output until the feedback signal matches the command input signal in the deviation comparator 8, and the motor 15 is output by the driver 15 via the amplifier 9 and the control command direction comparator 11.
Keep rotating.

By inputting the feedback signal to the differentiating circuit 10, while the motor 1 is operating, a signal from the differentiating circuit 10 is output, and the rotation direction signal is given to the digital comparison circuit 13 via the rotation direction comparator 12.

Now, when the output of the deviation comparator 8 is +, the control command direction signal from the control command direction comparator 11 outputs C · CW, and depending on the rotation direction of the motor 1 at that time, the rotation direction comparator 12
Is set so that the rotation direction signal of F · CW is output.

Conversely, when the output of the deviation comparator 8 is-, the control command direction signal C · CCW is output from the control command direction comparator 11 and the rotation direction comparator 12 outputs Is set so that a rotation direction signal of F · CCW is output.

In the digital comparison circuit 13, the C / CW control command direction signal and the F / CW rotation direction signal always coincide, or the C / CCW control command direction signal and the F / CCW
Is set so that a state in which both signals of the rotation direction signal are always the same is determined to be normal.

The operation will now be described on the assumption that a command input signal is given, and as a result, the output of the deviation comparator 8 is output to +.

Since the output of the deviation comparator 8 is +, the control command direction comparator 11
Outputs a C / CW control command direction signal, based on which a signal is output from the digital comparison circuit 13 to the driver 15, and the motor 1 starts rotating, and at the same time, the rotation direction comparator 12
Thus, a rotation direction signal of F · CW is output.

This state continues until the feedback signal matches the command input signal, that is, until the output of the deviation comparator 8 becomes zero.

In the process where the feedback signal and the command input signal match, if something gets stuck, the control command direction signal C · CW is output, but the rotation of the rotation direction signal F · CW is stopped because the motor 1 stops moving. The digital comparison circuit 13 determines that there is an abnormality because the signals are not output and the two signals are inconsistent, stops the output to the oscillator 14 and the motor driver 15, stops the motor 1, and outputs an alarm signal. .

When the feedback signal matches the command input signal, the output of the deviation comparator 8 becomes zero, and the output of the control command direction signals C and CW also stops.

The motor 1 is stopped via the driver 15 based on this signal. At this time, the output of the rotation direction signal F · CW also stops, and C
The digital comparison circuit 13 does not judge that there is an abnormality because the output matches the CW output, and no alarm is output.

In the embodiment, the stop position abnormality detection mechanism of the electric actuator regarding opening and closing of the valve has been described. However, it is needless to say that the mechanism can be used for the stop position abnormality detection mechanism of various actuators other than the valve.

Advantageous Effects of the Invention The present invention detects a stop position abnormality of an electric actuator using a control command direction signal and a rotation direction signal obtained from a feedback signal as described above. Unlike the one manufactured by using the above, it is possible to provide a small-sized and low-cost electric actuator stop position abnormality detection mechanism, and it is possible to promptly alarm or stop the motor at the time of an abnormal operation such as a foreign object being caught. Therefore, it is possible to prevent the accident of burning.

Further, since conductive plastic is used for the feedback mechanism, a durable and reproducible resistance value can be obtained, reliable feedback can be performed, and malfunction can be prevented. Further, the manual opening / closing member can detect the stop position abnormality of the electric actuator visually, and also can return the manual opening / closing member lightly at the time of abnormal operation, and can easily remove foreign substances and the like caught on the valve. Has an effect.

Furthermore, in the present invention, in particular, since a pulse motor is used for valve driving, digital control can be performed, signal processing is easy, and valve position accuracy can be finely controlled. Components can be omitted, and a stop holding force is generated by the detent torque of the motor, thereby exerting a strong effect on fluid tilt and the like.

[Brief description of the drawings]

The drawings show an embodiment used for a stop position abnormality detecting mechanism of the electric actuator according to the present invention. FIG. 1 is a front view of the electric actuator of the present invention, and FIG. 2 is a vertical sectional view at the center of FIG. FIG. 3 is a sectional view taken along the line AA of FIG. 2, and FIG. 4 is a control block diagram of the same. DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Output shaft 3 ... Slider 4 ... Actuator case 5 ... Conductive plastic 6 ... Manual opening / closing member, 7 ... Stopper part 8 ... Deviation comparator, 9 ... Deviation signal amplifier 10… Differentiator circuit 11… Control command direction comparator 12… Rotation direction comparator 13… Digital comparison circuit 14… Transmitter 15 Motor driver

Continued on the front page (72) Inventor Yoshihiro Hirayama 4-35-18 Gakuen, Musashimurayama-shi, Tokyo JP-A-43084 (JP, A) JP-A-62-178192 (JP, A) JP-A-58-49088 (JP, A)

Claims (3)

(57) [Claims] 1. An electric actuator for controlling a motor and a control output position by feeding back a detection signal of the motor and a control input position based on a deviation from a command input. The signals are branched, and one is input to a differentiating circuit to obtain a forward / reverse / stop rotation direction signal, and the other is compared with a command input signal to obtain a forward / reverse control command direction signal, A stop position abnormality detection mechanism for an electric actuator for a valve, characterized by detecting an abnormal biting state occurring in the valve by comparing the two. 2. The method according to claim 1, wherein when the actuator detects that the actuator has stopped in the middle of the control, the abnormality detection circuit of the valve detects the actuator.
In order to eliminate the cause of the abnormality, the actuator is rotated for a predetermined time to open the valve, or the normal / reverse rotation is repeated to remove the bite of the cause of the abnormality, and thereafter, the rotation is returned to the normal rotation. 1) A stop position abnormality detecting mechanism of the valve electric actuator according to 1). 3. A sliding element that slides on the surface of the conductive plastic is provided on a valve opening / closing operation shaft for detecting a detection signal of a valve opening position. The stop position abnormality detection mechanism for an electric actuator for a valve according to claim 1, wherein: