JPH06323459A - Actuator for valve - Google Patents

Abstract

PURPOSE:To dispense with an electromagnetic brake for fixing a rotary shaft of a motor by constituting the motor to open and close a valve as an induction motor to stop in a fixed condition when torque of not less than a constant value is applied still in a current-carrying condition. CONSTITUTION:When an output shaft 1 connected to a rotary shaft of a valve body is rotated by a reversibly rotatable motor 2 through a reduction gear 3, a valve A is opened. On the other hand, the valve A is closed by restoring force of a flat spiral spring 4 wound by rotation of the output shaft and driving force of the motor 2. In such an actuator, the motor 2 is constituted as an induction motor to stop in a fixed condition when torque of not less than a constant value is applied still in a current-carrying condition. An electric current is carried to the motor 2 through a resistor 5 by a signal from a microswitch D to detect opening of the valve A. A mechanical stopper 6 is arranged additionally to stop rotation of the output shaft when the valve A is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve actuator that controls the opening and closing of a valve body by driving a motor, and more particularly to a valve actuator that is closed by the restoring force of a mainspring when the valve is opened.

[0002]

2. Description of the Related Art A conventional actuator of this type having the structure shown in FIG. 3 is known.

FIG. 3 is a schematic side view of a conventional actuator. In this actuator, an output shaft 1 connected to a rotary shaft of a valve body of a valve A is driven by a reversible rotary motor 2 through a reduction gear 3. The valve A is rotated by 180 degrees to open the valve, and the valve A is closed by the restoring force of the main spring 4 wound directly by the rotation of the output shaft 1 and the driving force of the motor 2. When S is closed and the motor 2 is energized, the reduction gear 3 is rotated by the rotation of the gear 21 integral with the rotation shaft of the motor, the output shaft 1 integral with the reduction gear 3 is rotated, and the valve A
However, the output shaft is provided with a spring spring 4 having an inner end 41 fixed to the output shaft and an outer end 42 fixed to a fixing member B such as a casing. The mainspring 4 is wound by the rotation in the direction. An electromagnetic brake C is provided on the rotary shaft 21 of the driving motor 2, and when the output shaft 1 rotates to the valve open position, the contact of the micro switch D is kicked by a cam integrated with the output shaft 1. The circuit is closed, the relay Ry is excited, and the first
Since the contact point Ry1 makes a circuit to cut off the energization to the motor 2 and the rotation of the motor stops, the second contact point Ry2 closes to energize the coil of the electromagnetic brake C, so that the rotating shaft 21 of the motor is fixed and the mainspring 4 is rotated. Holds the wounded state. When the power switch is opened and the power supply to the motor 2 is cut off, the electromagnetic brake C becomes free, so that the output shaft 1 is rotated in the opposite direction to the opening direction by the unwinding force, that is, the restoring force of the power spring 4. , Valve A
Will be closed. That is, even in an emergency such as a power failure when the valve is open, the power is cut off and the electromagnetic brake C is also freed. Therefore, the valve A is also closed by the restoring force of the main spring 4.

As described above, in the actuator of the prior art, the electromagnetic brake C is used to fix the rotary shaft 21 of the motor 2, so that the direct-current low-voltage operated electromagnetic brake is operated. In addition to requiring a transformer and a rectifier, the space of the electromagnetic brake and transformer not only increases the size of the entire device, but in the case of a dry friction plate type electromagnetic brake, rust may occur at its contact part,
When water gets wet, the amateur may not be completely opened and the valve may not be closed in an emergency, which is a problem of low reliability.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve actuator which solves the above-mentioned problems of the prior art by using a driving motor as an induction motor which stops in a fixed state when a torque more than a certain level in the energized state is applied. It is intended to be provided.

[0006]

DISCLOSURE OF THE INVENTION In a valve actuator according to the present invention, an output shaft connected to a rotary shaft of a valve body of a valve is driven by a reversible rotary motor and is rotated by 90 degrees to 18 degrees through a reduction gear.
In the valve actuator in which the valve is opened by rotating it by 0 degree, and the valve is closed by the restoring force of the main spring wound by the rotation of the output shaft and the driving force of the motor, the driving motor is energized. The motor is an induction motor that stops in a fixed state when a torque above a certain level is applied, and the motor is energized by a signal from a microswitch that detects the opening of the valve through a resistor and the valve opens. It is characterized by providing a mechanical stopper that sometimes stops the rotation of the output shaft.

[0007]

When the valve is opened, unwinding of the mainspring is prevented by the constant stopping torque of the motor in the energized state, and the stopper prevents the valve from being overloaded.

[0008]

1 is a side view of a valve provided with an actuator of the present invention, and FIG. 2 is a schematic side view of the same actuator, the basic structure and action of which are substantially the same as those of the conventional actuator. Members having the same functions as those of 3 are given the same reference numerals. In the present invention, the electromagnetic brake C provided on the rotary shaft 21 of the motor 2 of the conventional actuator is removed, and when the valve A is opened, the contact of the micro switch D is closed to excite the relay R.
When the first contact point Ry1 of y is switched, the motor 2 is energized via the resistor 5, and the stop torque of the motor 2 is used to prevent the mainspring spring 4 from rewinding. A stopper 6 is also provided at the open position so that an overload is not applied in the direction.

When the valve is closed, the power switch S is closed,
When the motor 2 is energized in the valve opening direction, the output shaft 1 rotates in the valve opening direction via a plurality of reduction gears including the reduction gear 3 to open the valve A and at the same time the mainspring 4
Is wound, the micro switch D is closed at the valve open position to excite the relay Ry, and its contact Ry1 is switched to the terminal side for energizing the motor 2 via the resistor 5, so that the motor 2 has a lower current than when driven. Is supplied, a stop torque larger than the rewinding force of the mainspring spring 4 is obtained by the rotation stop by the stopper 6, and the mainspring spring 4 is stopped in a wound state. At this time, a lower current is flowing through the motor 2 than during driving, so that overheating does not occur even if the rotation of the rotor is stopped.

[0010]

According to the actuator of the present invention,
The drive motor is an induction motor that stops in a fixed state when a torque greater than a certain level in the energized state is applied,
The motor is energized via a resistor by a signal from a micro switch that detects the opening of the valve, and a mechanical stopper is provided to stop the rotation of the output shaft when the valve opens. Therefore, unlike conventional actuators that use an electromagnetic brake to fix the rotary shaft of a motor, a transformer and a rectifier are not required, and the space for the electromagnetic brake and the transformer enlarges the entire apparatus. Without such a thing
Also, as with a dry friction plate type electromagnetic brake, if the contact part rusts or water gets wet, the amateur will not completely open and the emergency valve will not close at all. It is not reliable.

[Brief description of drawings]

FIG. 1 is a side view of a valve including an actuator of the present invention.

FIG. 2 is a schematic configuration diagram of the actuator.

FIG. 3 is a schematic configuration diagram of a conventional actuator.

[Explanation of symbols]

 A valve B fixing member C electromagnetic brake D micro switch 1 output shaft 2 motor 3 reduction gear 4 spring spring 5 resistor 6 stopper

Claims (1)

[Claims] 1. A valve A is opened by rotating an output shaft 1 connected to a rotary shaft of a valve body of a valve A through a reduction gear 3 by driving a reversible rotary motor 2 to open the valve A, In the valve actuator in which the valve A is closed by the restoring force of the spiral spring 4 wound by the rotation of the output shaft 1 and the driving force of the motor 2, the driving motor 2 is supplied with a torque equal to or more than a certain level. In this case, an induction motor that stops in a fixed state is used, and the motor 2 is energized by a signal from a micro switch that detects opening of the valve via a resistor 5, and the output shaft is opened when the valve A is opened. 1. A valve actuator comprising a mechanical stopper 6 for stopping the rotation of 1.