JP2652718B2 - Electric actuator for valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial Application Field) The present invention relates to a rotary opening / closing type valve such as a ball valve and a butterfly valve or a vertically opening / closing type valve valve such as a gate valve and a globe valve. The present invention relates to an electric actuator for a valve for opening and closing by a valve.

(Prior art) This type of actuator is mounted on an upper part of a ball valve or the like, and a drive shaft of a motor provided inside is transmitted to an output shaft via a gear, and the output shaft is connected to a stem of the valve to connect the output shaft to a valve stem. Open and close the valve.

The stop of the valve body is performed by stopping the rotation drive of the motor when the valve body is fully opened, fully closed, or at a fixed angle of the intermediate opening.

Conventionally, as a means for detecting a certain angle, a limit switch or the like provided near the output shaft or the like has been operated by contacting a cam inserted into the output shaft or the like. For example, in the case of a ball valve, the ball is rotated to be surely stopped at a rotation angle of about 90 degrees, and is driven to open and close (Japanese Patent Publication Nos. 56-1503 and 47-4408).
No. 4).

(Problems to be Solved by the Invention) As described above, since the conventional position detection when the valve is fully opened or fully closed, a limit switch or the like having a mechanical contact is usually used. The conventional actuator has the following problems.

That is, the limit switch and the cam need to be provided with a switch for normal opening and closing, and a switch for stopping or transmitting a signal at an intermediate opening. The wiring between the switches, the terminal block for taking out signals to the outside of the actuator, and the number of cores of the cable are complicated and large in capacity, and the space inside the actuator is required.

Adjustment of the cam position when positioning the rotation angle of the actuator also loosens the fixing screws etc. provided on the cam once,
In addition to requiring some skill, such as tightening the fixing screw again while adjusting the positional relationship with the opening of the valve, the tightened fixing screw also has the inherent danger of loosening due to vibrations etc. caused when using the valve. I have.

Further, the coupling between the output shaft of the actuator and the rotary shaft of the valve element is transmitted directly or via a transmission mechanism such as a connector, and the driving force is transmitted. When the working accuracy of the meshing joint is increased, the positional relationship between the actuator and the opening of the valve is easily adjusted, but there is a problem that the cost increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is an electric actuator for a valve that has solved the conventional problems. The present invention does not use a cam and a limit switch as in the prior art, and a mechanism for reducing the driving force of a conventionally used motor. A part of the gears is used to obtain a valve position detection signal, and this signal is used to control the motor.
Further, it is an object of the present invention to provide an electric actuator for a valve which can be manufactured compactly and does not require any adjustment work even when driven for a long period of time.

Configuration of the Invention (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a motor and a motor driving force that are decelerated and transmitted to an output shaft via a speed reduction mechanism disposed on a base, In the valve electric actuator that opens and closes the valve valve body with the output shaft, a non-contact type for detecting the number of rotating teeth is provided on a gear that rotates at a position distant from the output shaft, of a reduction mechanism that meshes with a plurality of gears. A sensor is provided, and the non-contact type sensor is provided on the base and disposed at a position close to the tooth tip of the gear, and the motor control unit is controlled by a rotation tooth number detection signal of the sensor. It is an electric actuator.

In this case, it is preferable to employ a photoelectric sensor or a proximity sensor as the non-contact sensor. Also, in a signal processing circuit in the motor control unit, when the pulse signal detected by the non-contact type sensor has a pulse width equal to or greater than or equal to a predetermined pulse width, the pulse signal is detected and an alarm mechanism is provided. An electric actuator for a valve, wherein a detection plate or a detection tape is provided on an upper surface or a lower surface of an arbitrary gear constituting a reduction mechanism, and a rotation detection signal is obtained by a non-contact type sensor.

(Operation) In the electric actuator for a valve according to the present invention, the non-contact type sensor for detecting the number of rotating teeth is provided at a position close to the tooth tip of the gear constituting the motor reduction mechanism. When driven, the gear of the speed reduction mechanism rotates, and the non-contact sensor for detecting the number of rotating teeth measures the number of teeth of the gear. When the valve body rotates to a predetermined angle, the measured number of teeth becomes a predetermined count value. Based on this, the power supply switch for the motor is turned off, and the operation of stopping the drive source is performed.

Also, instead of measuring the number of teeth, when a detection plate or a detection tape is provided on the upper or lower surface of an arbitrary gear and a rotation speed detection signal is obtained by a non-contact type sensor, for example, in the case of a small valve, This has the effect of enabling reliable measurement of the rotation value, for example, when the measurement of a non-contact sensor is difficult due to a small gear.

In addition, as the non-contact type sensor, a photoelectric sensor or a proximity sensor is adopted, and this sensor detects the presence or absence of the uneven portion of the tooth tip of the gear. However, these sensors do not directly contact the gear, but do not directly contact the gear. In addition to preventing the drive force from being adversely affected, there is no need to provide a cam that has nothing to do with the drive transmission mechanism as in the past. This is advantageous in design.

In addition, since the signal processing circuit includes a circuit that detects when the pulse width exceeds a predetermined value, if something gets stuck before the valve is fully closed, the tip of the gear The pulse signal detected by the non-contact type sensor has a long duration of ON or OFF, which is different from that during normal driving, and this is detected and taken out as an abnormal driving signal. Therefore, abnormal operation can be immediately detected, which is advantageous for maintenance management of a machine using the valve.

Further, in the signal processing circuit, when the pulse width becomes equal to or less than a predetermined value, the present invention includes a circuit for detecting the pulse width. And the operation speed of the actuator increases. In this case, the state of the ON or OFF time width of the pulse signal detected by the non-contact type sensor due to the tooth tip of the gear is a short width different from that during normal driving,
This acts to detect this and take it out as a drive abnormality signal.

Therefore, abnormal operation can be immediately detected, which is advantageous in maintenance management of a machine using the valve.

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

FIG. 1 is a view showing a portion of an actuator for a valve. A support plate 2 is erected above a base 1 of the actuator, and a motor 3 is mounted on the support plate 2. An output shaft 6 of an actuator is provided on a drive shaft 4 of the motor 3 via gears 5a, 5b, 5c and 5d as a reduction mechanism of the driving force of the motor 3.

An optional gear 5b in the speed reduction mechanism, that is, a gear 5b that rotates at a position distant from the output shaft 6, is selected, and a non-contact sensor 7 that holds the gear 5b in a non-contact state at the passing position of the tooth tip is, for example, It is provided at an appropriate position of the speed reduction mechanism on the base 1 or the like for detecting the number of rotating teeth. When the tooth tip passes through the non-contact type sensor 7, the sensor is activated based on the presence or absence of the tooth tip between the non-contact type sensors 7. Then, the on / off signal is sent to the motor control unit 8.

As shown in FIG. 2, the motor control unit includes a signal processing circuit A, an integrating circuit B, and a switch 9. The signal processing circuit A performs differentiation, integration, or the like to generate a signal that can be easily integrated.
This is integrated by a known integrating circuit B, and the switch 9 between the motor 3 and the power supply 10 is turned off at a predetermined integrated value.

The setting of the integrated value is obtained by measuring in advance a signal generated in the non-contact sensor 7 when the gear 5b rotates in accordance with the predetermined opening and closing of the valve to be used, and uses it.

In the pulse processing of the signal processing circuit A, when a pulse having a width wider or narrower than the pulse width corresponding to the rotation speed of the normal gear 5b is detected, the pulse is detected as an abnormal signal, and an alarm such as a buzzer is generated based on this signal. It is configured to be connected to the mechanism 11.

FIG. 3 shows another embodiment, in which only an optional gear 5b constituting the speed reduction mechanism is taken out, and a detection plate 12 is attached to the upper surface of the gear. When an optical sensor is used as the non-contact type sensor, the detecting plate 12 is provided by alternately providing reflective portions and non-reflective portions on the same circumference, and detecting this by the optical sensor.

When a magnetic sensor is used, a magnetic plate (or a coating of a magnetic material or the like) may be used instead of the reflecting portion.

The non-contact sensor 7 is generally a high-frequency type, a capacitive type,
Magnetic types and the like are known, but these are appropriately selected according to the implementation.Especially, when using a magnetic sensor such as a Hall element, the gear 5b must be made of a magnetic material. Needless to say, all non-contact sensors other than the above sensors can be applied.

In the embodiment, the non-contact type sensor 7 is of a type in which a gear is held, but the present invention is not limited to this. That is, a method may be used in which the lower surface or the upper surface of the tooth tip of the gear is smooth-finished or a reflective tape is adhered using an optical sensor to determine the presence or absence of light reflection.

 Next, the operation of the present embodiment will be described.

A non-contact type sensor 7 for detecting the number of rotating teeth is provided at a position of a toothed tooth portion of a gear 5b constituting a speed reduction mechanism of the motor 3, that is, a gear 5b rotating at a position distant from the output shaft 6. In the case where an optical sensor is used, for example, when an optical sensor is used, an on / off signal for the sensor is generated when the tooth tip of the gear 5b passes through the optical path.

In this case, since a non-contact type sensor 7 such as a photoelectric sensor or a proximity sensor is employed, they do not directly contact the gears, and serve to prevent a bad influence on the driving force of the motor.

The signal is sent to the motor control unit 8, and the motor control unit 8 is provided with a signal processing circuit A for processing the signal. In some cases, noise pulses having a pulse width different from the predetermined pulse width are generated due to engagement play at the connection between the output shaft and the valve.

Therefore, the pulse width generated in the non-contact type sensor 7 due to the rotation of the gear at the time of the steady driving is made to select only a certain range before and after the pulse width.
Only the pulse signal having the predetermined pulse width is sent to the next integrating circuit B and counted.

Here, the pulse less than a certain range is cut as it is, but if the pulse width falls below a certain fixed pulse width, the speed of the gear 5b is increased, and the sealing material sliding on the valve body is worn. This indicates that the alarm has occurred, so that this is taken out as an abnormal signal, and the alarm mechanism 11 such as a buzzer is activated.

In addition, the pulse having a width larger than the predetermined range indicates that the speed of the gear 5b is low, and indicates that the valve body is in an abnormal rotation state such as an overload state.
This is taken out as a drive abnormality signal, and an alarm mechanism 11 such as a buzzer is operated.

Next, in the integrating circuit B, the number of pulses required for fully opening and closing the valve body is integrated, and when this number is reached, the switch 9 for connecting the motor 3 and the power supply 10 is disconnected. Therefore, for example, when the valve is fully closed with 100 pulses, the circuit is set in the 100-pulse integrating circuit B to open and close the valve.

Advantageous Effects of the Invention The present invention operates as described above, so that a non-contact type sensor can be used, and the speed reduction mechanism required for opening and closing the valve can be used as it is. Yes, it can be made compact, and since it is a non-contact switch except between the motor and the power supply,
In addition to ensuring a long service life and high reliability, there is no need to adjust the sensor part even when the sensor is driven for a long period of time.

Furthermore, the valve opening degree can be obtained in accordance with the purpose of the valve user, and abnormal effects such as seat abrasion and biting can be quickly detected.

In addition, among the reduction gears in which a plurality of gears mesh with each other, the non-contact type sensor provided on the base is provided close to the gear rotating at a position distant from the output shaft. High resolution can be obtained only by installing a sensor on the base, and there is no significant cost increase compared to conventional products. Having.

[Brief description of the drawings]

The drawings show an embodiment of an electric actuator for a valve according to the present invention. FIG. 1 is a perspective view of a main part of the present invention, FIG. 2 is a schematic explanatory view of an operating state of the same, and FIG. It is a perspective view of the gear part which shows the Example of FIG. 3 ... motor, 5b ... gear 6 ... output shaft, 7 ... non-contact type sensor 8 ... motor control unit, 9 ... switch 10 ... power supply, 11 ... alarm mechanism 12 ... detection plate A ... ... Signal processing circuit, B ... Integration circuit

Claims (5)

(57) [Claims] An electric actuator for a valve, wherein a motor and a motor driving force are decelerated and transmitted to an output shaft via a speed reduction mechanism disposed on a base, and the output shaft opens and closes a valve valve body. A non-contact type sensor for detecting the number of rotating teeth is provided on a gear rotating at a position distant from the output shaft, of the reduction mechanism in which the gears are meshed, and the non-contact type sensor is provided on a base and the gear described above. An electric actuator for a valve, wherein the electric motor actuator is disposed at a position close to a tooth tip of the motor, and a motor control unit is controlled by a rotation tooth number detection signal of the sensor. 2. The electric actuator for a valve according to claim 1, wherein the non-contact type sensor is a photoelectric sensor. 3. The electric actuator for a valve according to claim 1, wherein the non-contact sensor is a proximity sensor. 4. A signal processing circuit in the motor control unit, wherein a mechanism is provided for detecting when a pulse signal detected by the non-contact sensor has a pulse width equal to or larger than a predetermined pulse width and activating an alarm mechanism. The electric actuator for a valve according to any one of claims 1 to 3. 5. A detection plate or a detection tape is provided on an upper surface or a lower surface of one of the gears constituting the speed reduction mechanism, and a rotation detection signal is obtained by a non-contact type sensor.
The electric actuator for a valve according to any one of the above.