JPH07260024A - Swing check valve - Google Patents

Abstract

PURPOSE:To decrease pressure loss, so as to prevent damage of respective parts of a check valve by projecting and providing a bent plate for smoothing a back flow side fluid passage of a valve body at the time that fluid passage is opened from the inner wall of a valve box toward the back flow side lower end peripheral edge of the valve body. CONSTITUTION:A valve body 4 in normal flowing wherein fluid is allowed to flow from the left to the right is pushed up by fluid force and rotated around a valve shaft 5 and brought in contact with a stopper 8. In the flow of fluid in a valve box 1 in this state, the fluid discharged from a valve seat 7 is first brought in contact with the front surface of the valve body 4, and most of fluid is diffused to the right and the left and the lower part. The fluid has been passed the peripheral edge end of the valve body 4 is smoothly converged and allowed to flow out toward an outlet of the valve box l by a bent plate 6 arranged near the peripheral end edge without passing the back side of the valve body 4. At this result, a suddenly changed part such as a suddenly enlarged part of the fluid passage in the valve box 1 is decreased, and turbulence by vortex of the fluid is decreased, and fluid abrasion is decreased, moreover, pressure loss can be decreased. Therefore, pump lift can be lowered, and the cost can be saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing check valve applied to a liquid transfer piping system used in a nuclear power plant, a thermal power plant, a chemical plant or the like.

[0002]

2. Description of the Related Art A swing check valve, which is opened by a fluid force flowing in a fluid passage and when a fluid starts to flow backward, causes a valve body to automatically come into close contact with a valve seat and prevent the flow, includes a plant described above. Widely used for general industry.

FIG. 3 is a vertical sectional view showing a conventional swing check valve. Inside the valve box 01 with the valve lid 02 on the top,
Through the arm 03 in which the valve body 04 is fixed to the valve body 04,
It is rotatably supported around a valve shaft 05 installed in the valve box 1. When the fluid flows in the valve box 01 from the left side of the drawing, the valve body 04 is pushed up by the fluid force, and the center of the back surface of the valve body 04 is provided with a stopper protruding from the inner wall of the valve box 01. 08, the fluid passage is fully opened. Further, when the fluid flows back into the valve box 01 from the right side of the drawing, the valve element 04 is pushed down by the fluid force,
By rotating in the clockwise direction in the figure, the peripheral edge of the valve element 04 comes into contact with the valve seat 07 to fully close the fluid passage.

However, in the above-described conventional swing check valve, the shape of the fluid passage on the downstream side of the valve element 04 is large and has a large amount of discontinuity at the time of forward flow in which the fluid passage is fully opened. The flow of the fluid passing through the inside of the valve box 01 was disturbed, and the pressure loss was increased.

Further, at the time of reverse flow, the valve body 04 receives the fluid from the right side of the drawing, and the valve body 04 is suddenly closed, so that the valve body 04, the arm 03, the operating portion of the valve shaft 05, or the valve seat. In some cases, the pipe system was damaged by damaging the 07 and the stopper 08 or generating a water hammer effect.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-described problems of the conventional swing check valve. Therefore, at the time of forward flow, the fluid passage on the downstream side of the valve body is made smooth so that the valve body By forming a continuous fluid passage from the front to the rear, pressure loss is reduced and at the time of reverse flow,
An object of the present invention is to provide a swing check valve in which fluid acts on the valve element properly to prevent damage to each part of the swing check valve and to prevent a water hammer action from occurring.

[0007]

Therefore, the swing check valve of the present invention has the following means. A curved plate is projected from the inner wall of the valve box toward the lower edge of the downstream side of the valve body with the fluid passage fully opened to smooth the fluid passage on the downstream side of the valve body when the swing check valve is fully opened. did. Further, the tip of the curved plate may be arranged along the lower edge peripheral shape of the valve body downstream side, may be arranged separately, or may be in contact with the valve body.

[0008]

In the swing check valve of the present invention, the valve element is fully opened at the time of normal flow by the above-mentioned means, and the fluid flowing on the front side of the valve element circulates behind the valve element by the curved plate. Flow smoothly to the wake side along the inner surface of the curved plate and the inner surface of the lower portion of the valve box. Therefore, it is possible to reduce the occurrence of turbulence of the fluid such as a vortex generated on the back side of the valve body and reduce the increase in pressure loss due to the turbulence of the flow.

Further, in the reverse flow, the flow that was a normal flow in the fully open state is changed to a reverse flow in the initial stage of the reverse flow, and the fluid flow from the wake side is diverted downward by the curved plate, so that the fully open state is maintained. Since it does not hit the valve body, the valve body begins to fall by its own weight. After that, even at the intermediate opening degree, the fluid flow is diverted downward by the curved plate and is in a direction that does not match the rotation direction around the valve shaft of the valve body, so the fluid force acting on the valve body Remains weak. Eventually, in the vicinity of the closing, the gap between the valve body and the valve seat and the effective opening of the valve are narrowed and the flow rate is limited, so that the action of the fluid force becomes small, and the valve is closed by the static pressure difference. Therefore, since the action of fluid force can be limited from the full opening to the middle, the valve closing force is weakened, damage to each part due to sudden closing of the valve body can be reduced, and the water hammer action is prevented from occurring. It is possible to prevent damage to the piping system.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A swing check valve of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing an embodiment of the swing check valve of the present invention, and FIG. 2 is a partial cross-sectional view of a curved plate taken along the line AA of FIG. In FIG. 1, 1 is a valve box which is a main body of an outer shell of a swing check valve, 2 is a valve lid for sealing an opening provided in a central upper portion of the valve box 1, and 5 is a valve installed in the valve box 1. The shaft 3 has an arm pivotally attached to the valve shaft 5 at one end thereof and pivots around the valve shaft 5. Reference numeral 4 denotes a valve body having a wake-side center portion fixed to the other end of the arm 3; It projects from the inner wall of the box 1 in a front-down direction, and the tip of the valve body 4 is inserted as shown in FIG.
Is a curved plate disposed along the lower edge of the downstream side of the valve body 4 when fully opened. The front downward angle of the curved plate 6 is set so that the streamline becomes smooth when the valve body 4 is fully opened.

Further, 7 is a valve seat for preventing the fluid from flowing in the valve box 1 by fitting the peripheral edge of the valve body 4 when the valve body 4 is fully closed,
Reference numeral 8 is a stopper for limiting the fully open angle of the valve body 4 and limiting the fluctuation of the valve body 4 at the time of full opening.

Since the present embodiment is constructed as described above, in FIG. 1, the valve body 4 at the time of normal flow in which the fluid flows from left to right is pushed up by the fluid force and the valve shaft 5 is moved. It rotates around the center and hits the stopper 8. In the flow of fluid in the valve box 1 in this state, the fluid exiting the valve seat 7 first strikes the front surface of the valve body 4, and most of it diffuses left and right and downward. The fluid that has passed through the peripheral edge of the valve body 4 smoothly converges toward the outlet of the valve box 1 without going around to the back side of the valve body 4 due to the curved plate 6 that is installed close to the peripheral edge. Flowing. As a result, a sudden change portion such as a sudden expansion portion of the fluid passage in the valve box 1 is reduced, turbulence due to a vortex of the fluid is reduced, fluid friction is reduced, and pressure loss can be reduced.

In FIG. 1, fluid flows from right to left,
At the time of reverse flow, first, when the valve body 4 is in the fully open state at the time of forward flow, the flow is diverted for some reason, and in the initial state in which the flow is reversed, the fluid flows downward by the curved plate 6, Since the fluid does not hit the back surface of the valve 4, the valve element 4 gradually drops due to its own weight. In an intermediate state in which the valve body 4 has an intermediate opening degree when fully opened, the fluid flow direction is downward due to the curved plate 6, whereas the valve body 4 rotates around the valve shaft 5. Since the valve body 4 is moving and the back surface of the valve body 4 does not face the flow direction of the fluid, the collision force of the fluid on the back surface of the valve body 4 is small and the fluid force acting on the valve body 4 is small.
Further, when the valve is close to the fully closed state, the area of the annular opening formed by the valve body 4 and the valve seat 7 is reduced, and the flow rate flowing in the valve box 1 is reduced. Therefore, the fluid force of the valve body 4 is naturally reduced. It's getting smaller. From the above, during reverse flow, the fluid force acting on the valve body 4 can be reduced from the fully open state to the fully closed state.

As a result, there is almost no risk of damage to the operating portion including the valve body 4, the valve seat 7, the stopper 8 and the like, and the water hammer effect and the hunting effect due to the sudden closing of the fluid passage are eliminated. Occurrence can be prevented.

[0015]

As described above, according to the swing check valve of the present invention, due to the constitutions set forth in the claims, it is possible to reduce the pressure loss at the time of normal flow in which the swing check valve is fully opened. . This pressure loss reduction is
This leads to lowering the pump head and is also effective in reducing costs such as pump drive power.

Further, during reverse flow when the swing check valve is in a fully closed state, the sudden closing phenomenon is alleviated, and as a result, in the liquid delivery piping system, the valve body and the valve seat portion due to the sudden stop of the parallel pump and the like. It is possible to prevent damage, prevent damage to the valve and the piping system due to the water hammer action, and prolong the life of the swing check valve, which is industrially useful.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a swing check valve of the present invention.

FIG. 2 is a view taken along the line AA of FIG.

FIG. 3 is a vertical sectional view of a conventional swing check valve.

[Explanation of symbols]

 1 valve box 2 valve lid 3 arm 4 valve body 5 valve shaft 6 curved plate 7 valve seat 8 stopper

Claims (1)

[Claims] 1. A swing check valve for rotating a valve element around a valve shaft installed in a valve box to open and close a fluid passage,
A curved plate that smoothes the wake side fluid passage of the valve body when the fluid passage is opened is provided so as to project from the inner wall of the valve box toward the wake side lower end peripheral edge of the valve body. A characteristic swing check valve.