JP2002168360A - Actuator for valve - Google Patents

Abstract

(57) [Problem] To provide a valve actuator having a load protection function. SOLUTION: In a valve actuator provided with an output shaft for driving a valve in a casing and a motor for rotating the output shaft via a reduction gear in a direction in which the valve opens and closes, a reaction force of a rotational torque of the output shaft is provided. A pair of compression-type load sensors that detect the movement of the movable plate that fixes the motor as the valve opens and closes, converts the strength of the compression force into an electrical signal, and converts this signal to the rotational torque of the output shaft. When the value exceeds the rated rotation torque of the valve, the current flowing to the motor is cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve actuator having an overload protection function in an actuator for controlling opening and closing of a valve.

[0002]

2. Description of the Related Art As a conventional valve actuator having a load protection function, when a current flowing through a motor exceeds a rated current value for a certain period of time, it is determined that an abnormality has occurred, and the power supply to the motor is shut off, and the drive mechanism is turned off. Some are protected.

[0003]

In such a valve actuator, the overload state is not determined by directly measuring the rotational torque of the valve, but the current flowing through the motor is determined by the rated current value. Because it is to monitor whether it exceeds and judge whether it is abnormal or not.
If the motor rotates frequently in the forward and reverse directions, the starting current that exceeds the rated current value may flow through the motor, and this is erroneously determined as an overload. There is a problem that it is not possible to determine whether the motor is in the load holding state or the frequent forward / reverse rotation operation of the motor only by the value and the time.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems by providing a motor that rotates an output shaft that opens and closes a valve in a direction opposite to a rotational torque that rotates the output shaft on a plate that fixes the motor. It is an object of the present invention to provide a valve actuator which can detect whether a reaction force is generated by a compression-type load sensor and directly determine whether or not the load is maintained.

[0005]

According to the present invention, there is provided a valve actuator including, in a casing, an output shaft for driving the valve and a motor for rotating the output shaft via a reduction gear in a direction in which the valve opens and closes. In the valve actuator, there is provided a pair of compression-type load sensors for detecting the reaction force of the rotation torque of the output shaft as a movement of the movable plate for fixing the motor when the valve is opened and closed, and an electric signal indicating the strength of the compression force of the sensor. This signal is converted into a rotational torque of the output shaft, and when the value exceeds the rated rotational torque of the valve, the current flowing through the motor is cut off.

[0006]

The load holding state of the valve is detected by directly measuring the reaction force of the rotation torque of the output shaft with a compression type load sensor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a side view showing a state where the actuator of the present invention is attached to a valve, and FIG.
Is a side view of the main part showing the internal structure of the actuator,
FIG. 3 is a main part plan view showing the internal structure of the actuator.

Reference numeral 1 denotes a valve actuator according to the present invention, which is appropriately supported by a casing 11 for accommodating and protecting a driving portion, and an output shaft 1 protruding from a lower end of the casing 11.
2 is connected in a straight line to the stem of the valve V via a coupling C.

Reference numeral 2 denotes a reversible rotary motor for rotating the output shaft 12 in a direction in which the valve V opens and closes.
2 is fixed to a movable plate 3 pivotally supported via a bearing.

Reference numeral 4 denotes a group of reduction gears for transmitting the rotational force of the motor 2 to the output shaft 11, and includes spur gears 41, 42, 4
3, 44.

Reference numerals 5 and 6 denote compression-type load sensors which detect the movement of the movable plate 3 and convert it into electric signals. The compression-type load sensors are appropriately mounted on the casing 11 so as to sandwich a projection 31 formed on a part of the movable plate 3. Fixed.

Reference numeral 7 denotes a board on which a microcomputer for converting electric signals from the compression-type load sensors 5 and 6 into rotational torque of the output shaft 12 and a memory for storing rated rotational torque and the like are mounted.

In the figure, reference numeral 8 denotes an auxiliary plate for supporting the rotation shaft of the reduction gear group 4 between the movable plate 3 and the auxiliary plate 8. 9 is the output shaft 1
A group of fixed cams 2 is provided with limit switches that are pressed by the respective cams to open and close the contacts, and control energization when the valves are opened and closed.

Next, the operation and effects of the actuator of the present invention will be specifically described with respect to the first embodiment shown in the drawings according to the above configuration of the present invention.

When the motor 2 is energized in the direction in which the valve V closes while the valve V is open, the rotor of the motor 2 rotates in the direction indicated by the solid line, and the output shaft 12 is driven by the action of the reduction gear group 4 so that the output shaft 12 changes in the solid line. Rotating in the direction of the arrow opens the valve V in which the output shaft 12 and the stem of the valve V are linearly connected by the coupling C.

Conversely, when the motor 2 is energized in the direction in which the valve V is opened while the valve V is closed,
The rotor of the motor 2 rotates in the opposite direction to the above, and the valve V
Opens.

When the output shaft 12 is rotating in the valve closing direction, a force opposite to the rotation torque is applied to the movable plate 3, and the movable plate 3 rotates around the output shaft 12 in the direction of the solid line arrow in FIG. The protrusion of the movable plate 3 pushes the plunger of the compression type load sensor 5 for detecting the closing direction.

Since the compression type load sensor 5 converts the physical displacement amount when the plunger is pressed into an analog electric signal, this electric signal is converted by a microcomputer mounted on the substrate 7. The output torque is converted into a rotational torque of the output shaft 12.

When the value converted into the rotational torque of the output shaft 12 exceeds the rated rotational torque of the memory mounted on the substrate 7, that is, the overload state occurs during the closing operation of the valve V. Upon detection, the current flowing to the motor is cut off, and at the same time, it is notified that an abnormality has occurred when the valve is closed.

When the output shaft 12 is rotating in the valve opening direction, the movable plate 3 rotates in the direction of the dotted arrow in FIG. When the plunger of the compression type load sensor 6 for detecting the opening direction is pressed, an overload condition is detected during the opening operation of the valve V, and the current flowing to the motor is cut off. Let them know you were there.

Next, a second embodiment of the present invention will be specifically described with reference to the drawings. FIG. 4 is a main part side view showing the internal structure of the actuator according to the second embodiment of the present invention.
FIG. 2 is a plan view of a main part showing an internal structure of the actuator.

The actuator of the second embodiment uses a worm gear as a part of the reduction gear group 4. The torque from the motor 2 is transmitted to the output shaft 12 and rotates. Even though the motor 2 is a non-reciprocal type actuator that does not rotate, the arrangement of the movable plate 3, the projections 31, and the support plates 8 is different from that of the actuator of the first embodiment, but the operation is the same as that of the first embodiment. Since this is exactly the same as the case, a detailed description is omitted.

[0023]

According to the valve actuator of the present invention, an output shaft for driving the valve and a motor for rotating the output shaft via a reduction gear in a direction in which the valve opens and closes are provided in the casing. The actuator includes a pair of compression-type load sensors that detect a reaction force of the rotation torque of the output shaft as a movement of the movable plate that fixes the motor when the valve is opened and closed, and converts the strength of the compression force into an electric signal. Then, this signal is converted into the rotational torque of the output shaft, and when the value exceeds the rated rotational torque of the valve, the current flowing through the motor is cut off. The overload state of the valve is detected by directly measuring with a compression type load sensor. In addition, it has completely solved the problem that it is not possible to determine whether the motor is in the load holding state or the frequent forward / reverse rotation operation of the motor only by the current value and time flowing through the motor. An actuator can be provided.

[Brief description of the drawings]

FIG. 1 is a side view showing a state where an actuator of the present invention is attached to a valve.

FIG. 2 is a main part side view showing an internal structure of the actuator.

FIG. 3 is a plan view of a main part showing an internal structure of the actuator.

FIG. 4 is a side view of a main part showing an internal structure of an actuator according to a second embodiment of the present invention.

FIG. 5 is a plan view of a main part showing an internal structure of the actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Actuator 11 Casing 12 Output shaft 2 Motor 3 Movable plate 4 Reduction gear group 5 Compression type load sensor 6 Compression type load sensor 7 Substrate

Claims (3)

[Claims] 1. A valve actuator having, in a casing, an output shaft for driving a valve and a motor for rotating the output shaft via a reduction gear in a direction in which the valve opens and closes. A pair of compression-type load sensors that detect the force as the movement of the movable plate that fixes the motor when the valve opens and closes are provided, convert the strength of the compression force into an electric signal, and convert this signal into the rotational torque of the output shaft. A valve actuator characterized in that when converted to a value exceeding a rated rotation torque of a valve, a current flowing through the motor is cut off. 2. The reduction gear according to claim 1, wherein the reduction gear is a combination of spur gears, and a pair of compression-type gears for detecting a rotational force around the output shaft when a movable plate for fixing a motor for driving the output shaft is opened and closed. A load sensor is provided, converts the strength of the compressing force of the sensor into an electric signal, converts this signal into rotational torque of the output shaft, and the current flowing through the motor when the value exceeds the rated rotational torque of the valve. 2. The valve actuator according to claim 1, wherein the valve actuator is shut off. 3. The reduction gear according to claim 1, wherein the reduction gear is a combination of a spur gear and a worm gear, and detects a rotational force about the output shaft when the movable plate for fixing the motor driving the output shaft is opened and closed. The compression type load sensor is provided, and the strength of compressing the sensor is converted into an electric signal, and this signal is converted into a rotation torque of the output shaft, and when the value exceeds the rated rotation torque of the valve, the motor is driven. 2. The valve actuator according to claim 1, wherein a current flowing through the valve is interrupted.