JPH05263950A - Butterfly valve - Google Patents

Abstract

PURPOSE:To open or close the valve body of a butterfly valve smoothly as well as to enable it to cope with such a switchgear as small in the output of power. CONSTITUTION:In a butterfly valve which rotates a valve body 1 around a valve stem 2 and opens or closes a flow of fluid, a seat 3 sliding in a flowing direction of the fluid by dint of fluid pressure is installed in a valve box. In addition, there is provided a seat sliding mechanism 8 which slides this seat 3 so as to bring it contact with or separate it from the valve body 1 at a valve closing position by dint of pressure it the fluid taken in from the upstream side of the butterfly valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly valve for opening and closing the flow of gas or liquid, for example, a butterfly valve used for maintenance on an iron pipe in a water channel of a power plant.

[0002]

2. Description of the Related Art In a butterfly valve, a disc-shaped valve body having the same diameter as the inner diameter of a flow path is generally placed in a cylindrical valve box,
The valve shaft of the valve body is rotated to open and close the fluid flow. The seat (valve seat) in the valve box is generally fixed in the valve box. In some valve bodies, a rubber sheet is attached to a portion in contact with the seat in order to maintain airtightness with the seat.

[0003]

However, in the above-mentioned conventional butterfly valve, since the valve body and the seat are in pressure contact with each other, a large force is required when opening and closing the valve body, and in particular, a rubber seat is attached to the valve body. The butterfly valve has a structure in which the rubber sheet of the valve disc bites into the seat, and therefore the torque for opening and closing the valve disc becomes large, which requires a switch with a large output corresponding to it. there were.

The present invention has been made to solve such conventional problems, and it is an object of the present invention to provide a butterfly valve which can be smoothly opened and closed when opening and closing a valve body and which can be handled by a switch having a small output. Has a purpose.

[0005]

SUMMARY OF THE INVENTION A butterfly valve according to the present invention is a butterfly valve which opens and closes a fluid flow by rotating a valve body around a valve axis, and slides in a fluid flow direction by fluid pressure in a valve box. A moving seat is provided, and the pressure of the fluid that takes in this seat from the upstream side of the butterfly valve
A seat sliding mechanism that slides so as to abut and separate from the valve body in the valve closed position is provided.

[0006]

With the above structure, when opening and closing the valve body,
By moving the seat to a position away from the valve body at the valve closing position, the valve body can be opened and closed without touching the seat, so the torque required to open and close the valve body can be small, The switch that opens and closes the body can be small. Further, when the seat is moved to a position where it abuts against the valve body at the valve closing position, the valve body and the seat come into close contact with each other, and the airtightness between the valve body and the seat can be maintained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of a butterfly valve according to an embodiment of the present invention when the butterfly valve is opened, and FIG. 2 is a partial sectional view of a butterfly valve according to an embodiment of the present invention when the butterfly valve is closed. 1 in these figures
Is a valve body of a butterfly valve, and a valve shaft 2 of the valve body 1
A worm gear (not shown) is attached to the valve shaft 2, and a valve shaft 2 and an opening / closing device (not shown) are connected via the worm gear. The opening / closing device rotates the valve shaft 2 to open / close the valve body 1. .. A rubber sheet 1A is attached to the outer peripheral portion of the valve body 1 in order to improve airtightness with the seat 3. However, the present invention is not limited to the butterfly valve having the rubber sheet 1A.

Reference numeral 4 is a valve box of a butterfly valve, and a step portion 5 is formed in a circumferential direction of an inner peripheral wall of the valve box 4, and the step portion 5 is formed.
The seat 3 is fitted in and is slidably attached to the inner peripheral wall of the valve box 4 by a presser 6. The step 5
Is composed of a wide inner peripheral side step portion 5A on which the seat 3 slides and a narrow outer peripheral side step portion 5B formed on the outer peripheral side of the inner peripheral side step portion 5A into which the fluid flows. There is.

A slope is formed on the side of the flow passage 7 of the seat body 3A so as not to contact the seat 3 when the valve body 1 is opened and closed. Further, a piston 3B is formed on the valve body 4 side of the seat body 3A so as to project into the outer peripheral side step portion 5B, and the seat 3 is slid by a seat sliding mechanism 8 described later.

The seat sliding mechanism 8 has two pipe lines 8A and 8A.
B and four solenoid valves 8C, 8D, 8E and 8F. One of the conduits 8A is attached so that one end thereof communicates with the upstream side of the butterfly valve and the other end communicates with the upstream chamber 5B _{1 of} the outer peripheral side step 5B partitioned by the piston 3B. One end of the other conduit 8B communicates with the upstream side of the butterfly valve, and the other end communicates with the downstream chamber 5B _{2 of} the outer peripheral step 5B partitioned by the piston 3B.

Of the solenoid valves, the first solenoid valve 8C is provided on the discharge side of the T-shaped branch portion of the other conduit 8B, and the second solenoid valve 8D is provided on the upstream side. In one of the conduits 8A, the third solenoid valve 8E is provided on the discharge side of the T-shaped branch portion and the fourth solenoid valve 8F is provided on the upstream side with the same configuration.

Next, the operation of the butterfly valve having the above structure will be described. In FIG. 2, the valve body 1 of the butterfly valve has a flow path 7
This shows a state in which the valve body 1 is pressed against the seat 3 and the flow path 7 is closed. The states of the solenoid valves in this case are that the first solenoid valve 8C is open, the second solenoid valve 8D is closed, the third solenoid valve 8E is closed, and the fourth solenoid valve 8F is open. Therefore, the flow of the fluid in the other conduit 8B is stopped, and the fluid flows out from the chamber 5B ₂ on the downstream side, and the fluid flows from the conduit 8A into the chamber 5B ₁ on the upstream side, and the piston 3B Is pushed down to the downstream side to slide the sheet 3 to the downstream side.

Next, when opening the valve body 1 as shown in FIG.
The third solenoid valve 8E is opened and the fourth solenoid valve 8F is closed to stop the flow of fluid in one of the conduits 8A, and the upstream chamber 5B ₁
Fluid in a state of flowing out from the third solenoid valve 8E side,
The solenoid valve 8C is closed, the second solenoid valve 8D is opened, the fluid is caused to flow into the chamber 5B ₂ on the downstream side through the other conduit 8B, and the piston 3B is pushed upward to slide the seat 3 upstream. To move. Then, the switch is driven to rotate the valve body 1 in a direction parallel to the fluid in the flow path 7 to open the flow path 7. In addition, the valve body 1
In order to maintain the open state of, the solenoid valve is maintained in the above state.

From the state where the valve body 1 is opened as described above, FIG.
1 is closed, the first solenoid valve 8C is closed, the second solenoid valve 8D is opened, and the third solenoid valve 8 is opened.
After opening E and closing the fourth electromagnetic valve 8F to hold the seat 3 at the upstream position, the opening / closing device is driven to rotate the valve body 1 to a position perpendicular to the fluid flow direction, As shown in 2, the seat 3 is slid downstream and brought into pressure contact with the valve body 1 to close the flow path 7. The state of the solenoid valve in that case is the same as when the valve body 1 is closed, the first solenoid valve 8C is open, the second solenoid valve 8D is closed, the third solenoid valve 8E is closed, and the fourth solenoid valve 8F is open. Is.

As described above, by operating the seat 3 and the valve body 1, the valve body 1 does not bite into the seat 3 when the valve body 1 is opened and closed. Therefore, a small torque is required when the valve body 1 is opened and closed. , A rubber sheet 1 provided on the outer periphery of the valve body 1
Less wear of A is required.

The seat sliding mechanism 8 of the present invention is not limited to the structure of the above embodiment, and is not limited to the above structure as long as the seat 3 can be slid in the upstream direction and the downstream direction.
Moreover, the valve does not have to be a solenoid valve.

The butterfly valve may be used for a liquid flow path or a gas flow path.

[0018]

As described above, according to the present invention, since the valve body is not in pressure contact with the seat when the valve body is opened and closed, the torque for opening and closing the valve body is small, and the valve body is opened and closed. A small switch can be used.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a butterfly valve according to an embodiment of the present invention in an open state.

FIG. 2 is a partial sectional view of a butterfly valve in a closed state according to an embodiment of the present invention.

[Explanation of symbols]

 1 valve body 2 valve shaft 3 seat 4 valve box 7 flow path 8 seat sliding mechanism

Claims (1)

[Claims] 1. A butterfly valve that opens and closes a fluid flow by rotating a valve element around a valve axis, wherein a seat that slides in the fluid flow direction by the fluid pressure is provided in a valve box, and this seat is used as a butterfly valve. The butterfly valve is provided with a seat sliding mechanism that slides so as to come into contact with and separate from the valve body at the valve closing position by the pressure of the fluid introduced from the upstream side of the valve.