JP2002161990A - Driving unit for butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving unit for a valve by which the valve can be closed without lowering closing torque while reducing the speed of the rotating speed of a valve stem connected to a cylinder just before closing the valve, a foreign material can be discharged by opening the valve surely when the biting-in of the foreign material is caused between a valve disc and a valve seat, and actuation can be performed by a single actuating pressure, an accessory and a control mechanism are not needed outside the cylinder. SOLUTION: By providing a sub-chamber adjacent to a driving cylinder of a double-acting cylindrical unit performing opening and closing of the valve disc by driving the valve stem, by providing a sub-piston rod projecting into the inside of the driving chamber in the sub-piston disposed within the sub- chamber, by discharging the pressure in the sub-chamber with limiting it, by abutting the driving piston against the sub-piston rod just before closing the valve, by reducing the speed of the movement of the driving piston and by reducing the speed of the turning to the direction of closing the valve when the valve is closed, and also it is made it possible to open the valve surely by the three pistons when the valve is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly valve driving device, and more particularly to a butterfly valve driving device capable of changing a speed at the time of closing a valve body.

[0002]

2. Description of the Related Art Conventionally, it has been known to control the opening and closing of a line by attaching a butterfly valve to a pipeline through which various fluids flow, and to rapidly shut off or open the flow passage depending on the fluid in the pipeline. In the event of an emergency such as a disaster or accident, it is required to close the valve rapidly to minimize damage. Furthermore, in recent years, there has been a demand for accurate control of the flow rate with a butterfly valve, and even in such a case, a high-speed cylinder device is used as a driving device. However, when the valve element is driven by using a high-speed cylinder device, the valve element is rapidly pressed against the valve valve seat surface to close the valve element, so that the valve seat is easily damaged and there is a problem in durability. In addition, since the valve body is suddenly pressed against the valve seat surface to close the valve, the valve seat is damaged when foreign matter is caught, and when the valve is opened, the rotating torque is increased by the foreign matter, so that there is a problem that the drive cannot be performed. . In order to protect the valve seat by reducing the speed of the valve immediately before closing the valve, a cylinder device having a mechanism for gradually changing the speed until the valve closes has been proposed. No. 59-5191.

In a valve closing speed control device disclosed in Japanese Patent Publication No. 59-5191, an end of a piston rod of a cylinder device to which a valve shaft is connected just before the valve is closed is brought into contact with a piston rod of a hydraulic cylinder. And the cylinder is actuated in accordance with the moving speed of the hydraulic cylinder. However, such a valve closing speed control device has a structure in which a cylinder device connected to a valve shaft operates by pneumatic pressure, whereas a hydraulic cylinder that controls the speed of the cylinder device operates by hydraulic pressure such as hydraulic pressure. It requires an accessory and a control mechanism outside the cylinder device, requires two types of cylinder devices with different pressure sources, complicates the mechanism, prepares a plurality of operating pressure sources, and provides a switching valve. In addition, since various operating devices such as a flow control valve must be prepared corresponding to a plurality of operating pressures, there is a disadvantage that the cost is increased and the control is complicated.

[0004]

SUMMARY OF THE INVENTION The present invention enables a valve to be closed without reducing the shut-off torque while reducing the rotational speed of a valve stem connected to a cylinder immediately before the valve is closed. It is intended to provide a valve driving device which can be operated at an operating pressure of 0.1 mm and which does not require any accessories or a control mechanism outside the cylinder.

[0005]

Means taken by the present invention to solve the above-mentioned problem is that a sub-chamber is provided adjacent to a driving cylinder of a double-acting cylinder device which drives a valve stem to open and close a valve body. A sub-piston rod protruding into the driving cylinder is provided on the sub-piston arranged in the sub-chamber, and the pressure in the sub-chamber is exhausted while restricting the pressure when the valve is closed. When the valve is in contact with the piston rod, the movement of the drive piston is reduced to reduce the rotation of the valve body in the valve closing direction.
It is characterized by the fact that one piston can be reliably opened by two pistons.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below. According to the present invention, a sub-piston having a sub-piston rod formed in a sub-chamber is formed adjacent to a pressurizing chamber of a double-acting cylinder device that opens and closes a valve body by driving a valve stem. Arranged, the sub-piston rod can be freely retracted into and out of the pressurized chamber of the double-acting cylinder,
Immediately before closing the valve, the valve driving piston is allowed to move rapidly due to rapid exhaust, and immediately before closing the valve, the valve driving piston is brought into contact with the sub-piston rod that is receiving resistance due to the exhaust from the contraction section. The operation of the valve driving piston is decelerated, and the rotation of the valve body in the valve closing direction is reduced and the valve body is slowly rotated. When the valve driving piston is pressurized in the valve opening direction, the sub-piston is pressurized at the same pressure as the pressurizing chamber by the port switching of the flow path switching valve, and the sub-piston rod projects into the pressurizing chamber. Then, the piston of the pressurizing chamber is further pushed out. Further, when the valve is driven in the valve closing direction from the fully opened position, the flow path switching valve is switched, and the pressure in the sub chamber of the sub piston is discharged via the throttle valve, and the return movement of the sub piston is performed. Limited by resistance. The pressure in the pressurized chamber is rapidly reduced due to rapid exhaustion of the pressurized chamber, and the valve is rapidly rotated until immediately before closing. Immediately before closing the valve, the valve driving piston comes into contact with the sub-piston rod, and the resistance of the contraction portion of the throttle valve acts to slow down the rotation of the valve and avoid sudden closing of the valve. Damage to the valve seat due to collision can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, (1) is a valve stem of a rotary valve such as a butterfly valve having a rotating valve element, and a piston rod (3) for driving a valve of a double-acting cylinder device (2). Arm
(4) and is rotated by the operation of the double-acting cylinder device. Double-acting cylinder device (2)
It has a structure in which driving pistons (7) and (8) arranged in driving cylinders (5) and (6) are connected to both ends of one valve driving piston rod (3), respectively. The driving piston is pressurized and actuated by the pressure introduced into the valve, whereby the valve driving piston rod (3) is reciprocated. A sub-chamber (9) is partitioned and provided adjacent to the driving cylinder (5) located on the valve closing direction side of the piston rod (3), and the sub-piston rod ( A sub-piston (10) having 11) is arranged in the sub-chamber (9).

[0008] Pressure is introduced into the driving cylinders (5) and (6) to pressurize the driving pistons (7) and (8), and the piston rod (3) is pressed.
Is operated to open the valve body. When the valve is closed, the cylinder
(5) Drive piston at the same time as the pressure inside (6) is exhausted
(7) The opposite side of (8) is pressurized, and the piston rod (3) is rapidly moved in the valve closing direction to close the valve. The sub-chamber
The supply and discharge of pressure to (9) are controlled by a switching valve (13), and the speed is controlled by a throttle valve (12) when discharging pressure. Sub piston rod (11) when pressurized
Protrudes into the drive cylinder (5), and immediately before the valve is closed, the drive piston (7) is connected to the sub piston rod (11).
And decelerates the movement of the driving piston (7). Drive piston rod with deceleration of drive piston (7)
The movement of (3) is also decelerated, the rotation of the valve stem (1) becomes slow, and the valve body is slowly seated on the valve seat and the valve is closed.

Referring to FIG. 1, the figure shows a fully closed state of the valve. In this state, when the switching valve (13) is switched to the right port as shown in FIG. Flow into the left side of (7) and (8), and at the same time, sub-piston (10)
Flows into the left side of FIG. The valve driving pistons (7) and (8) move rightward in the figure. The rightward movement of the valve driving pistons (7) and (8) causes the valve driving piston rod (3) to move rightward and the valve stem (1) connected by the arm (4) to move in the valve opening direction. It is driven and rotated, and the valve is opened as shown in FIG. Further, pressure is also introduced into the sub chamber (9), the sub piston (10) operates, and the sub piston rod (1) is actuated.
1) protrudes into the drive cylinder (5). At this time, if an abnormal rotation torque is acting on the valve stem, the moving speed of the driving pistons (7) and (8) becomes slow,
(10) surely moves in close contact with the piston (7) to open the valve body.

In order to rotate the valve body in the valve closing direction from the fully opened state, first, as shown in FIG. 4, the port of the switching valve (13) is switched to drive the driving pistons (7) and (8) in the valve opening direction. At the same time as discharging the pressurized pressure into the atmosphere, air pressure is supplied to the opposite side of the driving pistons (7) and (8), and the piston rod is released.
(11) is driven in the valve closing direction. By the exhaust and pressurization, the valve driving pistons (7) and (8) rapidly move to the left in the figure, and the valve rod (1) connected to the piston rod (3) is rotated in the valve closing direction. . Immediately before closing the valve, the valve drive piston
(7) abuts on the sub piston rod (11),
(10) is pushed in against the resistance added by the throttle valve. Therefore, the movement of the valve driving piston (7) is decelerated, and the deceleration of the piston is transmitted to the valve stem (1) via the piston rod (3), and the rotation of the valve stem (1) is slowed down. The body closes against the valve seat at a slow speed just before the valve closes. Therefore, the valve body and the seat ring do not suddenly come into contact with each other, and the seat ring can be prevented from being damaged. In this case, the piston for valve drive (7)
Does not change, and the valve closing torque of the valve rod (1) rotated via the piston rod (3) does not decrease.

[0011]

According to the present invention, since the operation of the valve driving piston is decelerated immediately before the valve is closed, it is possible to avoid a sudden contact between the valve body and the valve seat, and to prevent a sudden foreign matter from being produced. Prevention of biting, the durability of the valve seat is improved, and the service life can be extended. Also, the valve can be opened without deceleration when operating from the valve-closing position to the valve-opening position, and can be decelerated only when opening and closing the valve. Furthermore, even if foreign matter is caught in the valve seat when the valve is closed, the valve can be reliably opened and the foreign matter can be discharged.Also, replace the existing single-acting type cylinder partition with a partition unit equipped with a depressurizing piston. If so, it can be changed to the drive device having the opening / closing speed variable function of the present invention, and the specification can be changed easily and inexpensively.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing the structure of the present invention;
Shows valve-closed position

FIG. 2 is a view similar to FIG. 1, showing a state where the valve is switched from a valve closing position to a valve opening position.

FIG. 3 is a view similar to FIG. 1 showing a fully opened state;

FIG. 4 is a view similar to FIG. 1, showing a state immediately before valve closing;

[Explanation of symbols]

 (1) Valve rod (2) Double-acting cylinder device (3) Valve driving piston rod (4) Arm (5) Driving cylinder (6) Driving cylinder (7) Driving piston (8) Driving piston ( 9) Sub chamber (10) Sub piston (11) Sub piston rod (12) Throttle valve (13) Switching valve

Claims (1)

[Claims] 1. A sub-chamber is provided adjacent to a driving cylinder of a double-acting cylinder device for driving a valve stem to open and close a valve body,
A sub-piston rod is provided on the sub-piston disposed in the sub-chamber to protrude into the driving cylinder, and when the valve is closed, the pressure in the sub-chamber is discharged while restricting the pressure. By contacting, the movement of the driving piston is decelerated and the rotation of the valve body in the valve closing direction is decelerated, and when the valve is opened, the three pistons can reliably open the valve. Butterfly valve drive.