JPS6111521Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electro-hydraulic conversion torque actuator suitable for controlling the opening and closing of a shutoff valve such as a ball valve.

An electric-hydraulic conversion torque actuator uses a motor pump to generate hydraulic pressure, which operates a cylinder and converts it into rotational force, so it can be used to open and close a ball valve as a cutoff valve for fuel gas, etc. suitable for remote control.

However, in case of a power outage or failure, such actuators must be able to self-return by the reaction force of the spring and close the valve when the generation of hydraulic pressure is stopped. Because of the sliding resistance between the valve body and the housing, the ball valve requires a particularly large driving torque at each angle at the beginning and end of the valve opening/closing operation, which necessitates the return spring to be large in size. The drawback was that the entire actuator became larger.

Therefore, an object of the present invention is to provide a torque actuator that is small and has a large return torque.

In the present invention, a piston is movably provided in a cylinder tube fixed to the side of the housing, one end of a long piston rod passing through the housing is fixed to the piston, and the other end of the piston rod is fixed with a main return spring. The piston rod and the drive shaft rotatably supported by the housing are connected by a mechanism that converts linear motion into rotational motion.
The hydraulic conversion torque actuator is configured by providing an auxiliary return spring in the cylinder tube that is shorter than the stroke of the piston and presses the piston in the same direction as the main return spring only when the piston starts its return operation. has been done.

In the above configuration, when fluid pressure is applied to the piston to move the piston, the piston moves against the forces of the main and auxiliary return springs, but at the beginning of its movement, the auxiliary return spring is not acting on the piston. Therefore, the piston begins to move with a large force.

On the other hand, when the fluid pressure acting on the piston is released from the state where the piston is at the end position, the piston is returned to its original position by the action of the main and auxiliary return springs. Since the auxiliary return spring is acting on the piston, it starts returning rapidly.

An embodiment of the torque actuator according to the present invention will be described below with reference to the drawings.

1 and 2, a torque actuator 1 of this embodiment is shown. The torque actuator 1 includes a housing 2 having two chambers 20 and 21 divided into an upper and a lower chamber, and a drive shaft 3 is rotatably supported within the chamber 21. One end of the drive shaft 3 (lower end in the figure)
is protruded from the housing so that it can be connected to a valve shaft or the like of the ball valve.

A fluid pressure cylinder 4 is mounted on one side (the left side in FIG. 1) of the chamber 21 of the housing 2, and a spring housing 5 is mounted on the opposite side with its axis offset from the axis of the drive shaft 3. There is. The fluid pressure cylinder includes a cylinder tube 40 with end covers 41 and 42 fitted at both ends, a piston 43 movable within the cylinder tube 41, and a piston 43 extending through the housing 2 and having one end connected to the piston 4.
3 and a long piston rod 44 fixed thereto.

A spring housing 5 is fixed to the opposite side of the housing 2. The other end of the piston rod 44 extends into the spring housing 5, and a spring receiver 45 is attached to that end. A double main return spring 6 is provided within the spring housing and biases the piston rod 44 and piston 43 to the left (as viewed in FIG. 1).

An auxiliary return spring 7 that is shorter than the stroke of the piston 43 is provided within the cylinder tube. In this embodiment, one end of the auxiliary return spring 7 is fitted into a recess 430 of the piston 43.

The drive shaft 3 and the piston rod 44 are connected by a mechanism (hereinafter referred to as a linear-rotational motion mechanism) 8 that converts linear motion into rotational motion. This straight line-
The rotational movement mechanism 8 includes a pair of arms 80 fixed to the drive shaft 3, and a groove 81 rotatably attached to the piston rod 44 and formed at the tip of the arm.
A pair of rollers 82 received within the piston rod convert the linear motion of the piston rod into rotational motion of the drive shaft.

The upper chamber 20 of the housing 2 forms an oil tank for storing hydraulic oil for the hydraulic cylinder 4, and a hydraulic unit 9 having a pump 90, a motor 91 for driving the pump, a pressure switch 92, and a relief valve 93 is housed therein. has been done. This hydraulic unit 9 is adapted to send hydraulic pressure through a conduit 94 into the cylinder chamber 46 of one of the hydraulic cylinders by operation of a pump. The other cylinder chamber 47 communicates with the oil tank 21 via a conduit 95.

The housing 2 includes a hydraulic cylinder 4a, a spring housing 5a, a main return spring 6a, and an auxiliary return spring 7, which are different from the hydraulic cylinder 4, spring housing 5, main return spring 6, and auxiliary return spring 7.
As shown in FIG. 2, the hydraulic cylinders 4a are mounted in parallel across the drive shaft and in opposite directions, and this hydraulic cylinder 4a also operates simultaneously with the hydraulic cylinder 4 by the operation of the hydraulic unit 9.

A position detection switch 100 is installed in the chamber 21 of the housing 2 to detect the operating state of the fluid pressure cylinder.

In the above torque actuator, when the operating switch (not shown) of the hydraulic unit 9 is turned on, the motor 91 and pump 90 start to start, and the relief valve 93 closes. The hydraulic pressure pressurized by the pump 90 is supplied to each cylinder chamber 46 and 46a of the hydraulic cylinders 4 and 4a through a conduit 94. Therefore, the piston and piston rod of the hydraulic cylinder 4 are indicated by the arrow X.
The piston and piston rod of the hydraulic cylinder 4a simultaneously move in the direction of arrow Y, causing the drive shaft 3 to rotate in the direction of arrow Z. When the valve shaft of a ball valve (not shown) is connected to the drive shaft, the ball valve becomes fully open when each piston moves to its final position, and this is detected by the position detection switch 100. The operation of the motor and pump is stopped and the piston is kept in a pressed state, that is, the ball valve is kept in a fully open state.

When the power to the hydraulic unit 9 is cut off for some reason and the relief valve 93 is opened, the hydraulic pressure in the cylinder chamber 46 escapes into the oil tank 20 (which has the same pressure as atmospheric pressure) via the relief valve, so that each fluid The piston, piston rod, etc. of the pressure cylinder instantly return to their original positions by the action of the main and auxiliary return springs 6, 6a and 7, 7a, and the ball valve is accordingly closed.

Moreover, since the auxiliary return springs 7 and 7a are compressed against the end cover 42 when the piston, etc. starts to return, they effectively assist the restoring force of the main return spring, thereby overcoming the resistance force when starting the ball valve. The ball valve can be closed quickly and reliably. Moreover, since the auxiliary return spring only needs to act when the piston starts returning, it can be made small, and the actuator itself can therefore be made small.

Furthermore, since the hydraulic unit installed in the oil tank 20 is equipped with a pressure switch 92 that operates when the oil pressure increases, some kind of abnormality such as rusting of the ball valve may occur, causing a significant increase in starting resistance. Sometimes, the discharge pressure of the motor pump rises accordingly, and when it exceeds a predetermined pressure, the operation is stopped by actuation of a pressure switch. Therefore, even if the ball valve becomes rusty, it will not be forced open, making it extremely safe.

As described above, according to the present invention, since the mechanism of the return spring for the piston is made smaller, the actuator itself can also be made smaller, and moreover, reliable operation can be achieved.

In this embodiment, two sets of fluid pressure cylinders, return springs, etc. are used, but only one set may be used.

Further, the linear-rotary motion mechanism is not limited to the one shown, but may have other configurations, such as a rack and pinion mechanism.

Furthermore, the direction of action of the return spring may be reversed from that shown.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a torque actuator according to the present invention, and FIG. 2 is a sectional view taken along the line - in FIG. DESCRIPTION OF SYMBOLS 1...Torque actuator, 2...Housing, 3...Drive shaft, 4...Fluid pressure cylinder, 6,
6a...Main return spring, 7,7a...Auxiliary return spring, 8...Linear-rotary motion mechanism, 9...Hydraulic unit, 40...Cylinder tube, 43...Piston, 44...Piston rod.

Claims (1)

[Scope of utility model registration request] A piston is movably provided in a cylinder tube fixed to the side of the housing, one end of a long piston rod passing through the housing is fixed to the piston, and the other end of the piston rod is pressed by a main return spring. In an electro-hydraulic conversion torque actuator in which a piston rod and a drive shaft rotatably supported by the housing are connected by a mechanism that converts linear motion into rotational motion, the return operation of the piston is started within the cylinder tube. A torque actuator characterized in that an auxiliary return spring is provided that is shorter than the stroke of the piston, which only occasionally presses the piston in the same direction as the direction of pressure of the main return spring.