JPH07269727A - Swing check valve - Google Patents

Abstract

PURPOSE:To provide a swing check valve which does not generate water hammer when normal flow is changed to counter flow. CONSTITUTION:A swing check valve is prepared by providing a valve body for closing a valve seat on the side of the valve seat of an arm rotatably hung by mens of a hinge substantially horizontal to an inner portion of a valve box. In such a valve, a projection 6 is projected so as to fit into an inner periphery of the valve seat on the side of a valve seat 7. A groove 6a is formed so as to be shallow from a lower and outer edge of the projection 6 toward a center portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear power supply pipe system and other swing check valves.

[0002]

2. Description of the Related Art FIG. 6 is a vertical sectional view of a conventional swing check valve. Inside the valve housing 1 having the valve housing lid 2 on the top, the valve body 4
Is rotatably supported by a substantially horizontal hinge pin 8 via an arm 3 fixed to the valve seat 7 side of the valve body 4. In the case of a normal flow that flows from the left side of the figure, the valve body 4 is pushed up as shown by the dynamic pressure of the fluid from the left side, and the back surface of the valve body 4 contacts the stopper 5 and is in a fully opened state. When the backflow flows from the right side of the figure, the flow of the fluid from the right causes the valve body 4 to rotate in the clockwise direction of the figure, so that the periphery of the valve body 4 has a valve seat 7
And comes into a fully closed state.

In the figure, reference numeral 1a is an open cylindrical portion.

[0004]

The conventional swing check valve described above has the following problems to be solved.

That is, in the conventional swing check valve, when the flow is changed from the forward flow to the reverse flow as described above, the difference between the backflow fluid pressures applied to the abdominal and back surfaces of the valve body 4 on the valve seat 7 side is determined by the valve body. 4 rapidly rotates, collides with the valve seat 7 and momentarily closes,
There was a problem that a water hammer phenomenon might occur and not only the valve but also various parts of the pipe system might be damaged.

In order to solve the above problems, the present invention aims to provide a swing check valve in which damage due to water hammer is prevented by relaxing the closing speed of the valve body when the flow changes from normal flow to reverse flow. And

[0007]

As a means for solving the above-mentioned problems, the present invention provides a valve body for sealing a valve seat on the valve seat side of an arm rotatably hung inside a valve casing by a substantially horizontal hinge. In the swing check valve, the projection is provided on the valve seat side of the valve body so that it can be fitted into the inner circumference of the valve seat, and the projection is formed so that it gradually becomes shallower from the lower outer edge of the projection toward the center. The present invention is intended to provide a swing check valve, which is characterized by including a groove formed therein.

The term "horizontal hinge" means the hinge posture in a state where the cylinder axis of the check valve is positioned horizontally, that is, in the state as shown in FIG. The posture at the time of use is not restricted by this.

[0009]

Since the present invention is constructed as described above, it has the following actions.

First, the principle of water hammer generation in a swing check valve is as follows. In a space closed by abruptly shutting off the fluid that tries to flow in the opposite direction, the incompressible material which loses its field of motion is lost. It is due to the peak pressure generated immediately before the valve when the valve (valve body) is momentarily strongly pressed by the inertial force of the fluid.
Of course, not only valve shutoff, but if fluid having an incompressible velocity is suddenly shut off in a closed space such as a pipeline, flow velocity, fluid density, flow rate per shutting area (pipe cross-sectional area x pipeline It is a well-known fact that this phenomenon occurs depending on the length, etc., and its strength depends on the square of the flow velocity. In this case, this phenomenon, that is, the water hammer is remarkably alleviated if there is an escape area for the fluid which is pressed against the following fluid by being blocked.

For example, if the pipe body is highly flexible in the pipe line, the pipe body gradually decreases from the vicinity of the cutoff portion to the upstream, momentarily, the swelling and the water hammer are alleviated, and the fluid is restored again by the complete rest of the fluid. Become.

Therefore, if the pressed fluid can escape (flow) under the gap between the valve body and the valve seat,
The water hammer phenomenon will be alleviated, but at that time, the larger the time immediately before the interruption or the time from the beginning of the interruption to the end of the interruption,
Strictly speaking, for example, the longer the time until the flow velocity of the fluid within the fixed pipeline length starts to decelerate and stops, or more specifically, the smaller the fluid stop speed, the smaller the water hammer and the constant deceleration rate. To some extent, it is desirable in the sense that there is no unevenness in water hammer.

According to the present invention, the swing check valve is provided with a projecting portion projecting on the valve seat side of the valve body so that it can be fitted into the inner periphery of the valve seat, and the projecting portion is drilled so as to become gradually shallower from the lower outer edge toward the center. Since it has a groove provided, the flow rate of the fluid that has started to flow back while pushing the valve element back toward the valve seat side decreases as the opening degree of the valve element decreases and the flow velocity decreases, but the valve element itself Although the protrusion fits into the valve seat before contacting the valve, the flow rate is reduced, but the reverse flow continues from the groove, and the flow rate as a whole continues to decrease. That is, the flow velocity is reduced but still maintained. As the protrusion fits into the valve seat, the opening area of the groove decreases, and when the protrusion is completely fitted, the valve body comes into close contact with the valve seat and the flow stops completely. Therefore, in the conventional case, a relatively large amount of fluid that had flowed between the valve outer periphery and the valve seat suddenly stopped due to the close contact between the valve body and the valve seat, causing a large water hammer, In the configuration of the present invention, the protrusion having the groove is first fitted into the valve seat before the valve body is brought into close contact, the flow rate is greatly reduced, and the flow rate (and hence the flow rate) is gradually reduced according to the depth of the fit. As a result, the stopping speed of the fluid is reduced so that a water hammer does not occur or is remarkably reduced.

At this time, since the groove is provided with an inclined bottom so that it gradually becomes shallower toward the center of the protrusion from the lower outer edge, the fluid flowing into the valve seat side, that is, the downstream side when viewed from the reverse flow is Stable flow into the vicinity of the center along the downstream surface of the protrusion, and no alternating pressure or large vortex is generated, so
The change in pressure on the downstream side is small and the valve body does not vibrate.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The same components as those in the conventional example are designated by the same reference numerals,
The description is omitted unless necessary.

FIG. 1 is a longitudinal sectional view of the swing check valve of this embodiment, FIG. 2 is a detailed view of the valve body 4 and the like in FIG. 1, (a) is a side sectional view, and (b) is a view of the valve body 4. FIG. 4 is a front view, FIG. 3C is a perspective view of FIG. 3B, FIG. 3 is a schematic view showing a state of reverse flow in the intermediate opening state of the valve body of this embodiment, and FIG. FIG. 5 is a schematic diagram showing a state in which the valve body of the present embodiment is fully closed by backflow.

In FIG. 1, reference numeral 3 denotes an arm rotatably suspended inside a valve casing 1 by a substantially horizontal hinge 8.
Is a valve body provided on the valve seat 7 side of the arm 3 so as to be able to seal the valve seat 7, and 6 is a valve body abdomen projectingly provided on the valve seat 7 side of the valve body 4 so as to be fitted into the inner periphery of the valve seat 7. The convex portion 6a is a groove formed so as to be gradually shallower from the lower outer edge of the valve body abdominal surface convex portion 6 toward the center of the valve body 4.

The valve body 4 has the specifications shown in FIG. That is, Y is the protrusion height of the valve body abdominal surface convex portion 6, and W is the groove 6a.
, D is the diameter of the convex portion 6 of the valve body abdominal surface. W = 2 in the figure
However, the present invention is not limited to this, and as shown in FIG. 1, for example, as shown in FIG. 1, from the moment the lower end of the valve body abdominal surface convex portion 6 starts to be fitted into the valve seat 7 to the end of fitting. 4 is determined by experiments or the like so that the flow rate flowing to the left of 4 is appropriately reduced, that is, the closing speed is reduced.

The other structure is the same as that of the conventional example shown in FIG.

As shown in FIG. 1, the opening of the opening cylindrical portion 1a in the upper center of the valve casing 1 which is sealed by the valve lid 2 is provided for attaching / detaching the valve body 4 and for inspecting the inside of the valve. ing. In addition, one end of the arm 3 is fixed to the back surface of the valve body 4, and the other end is attached to the valve casing 1 by a hinge pin 8, and the valve body 4 is moved from the fully closed state to the fully opened state via the arm 3 and the hinge pin 8. It is attached to the valve casing 1 in a freely rotatable manner. The valve seat 7 is formed so that the peripheral portion of the valve body 4 is in close contact with it in the fully closed state. The stopper 5 is provided to prevent the valve body 4 from vibrating at the time of forward flow. The stopper 5 is provided with a convex portion formed at the center of the back surface of the valve body 4 when the valve body 4 is fully opened as shown in FIG. Shape so that the valve body 4 does not open further when touching,
The position is determined, and it is integrally formed inside the valve casing 1.

In FIG. 4, when the flow is normal, the fluid flows from the left to the right in the figure, so the valve body 4 rotates counterclockwise about the hinge pin 8 to open and fully open due to the fluid pressure from the left to the right. In the state, as shown in the figure, the convex portion on the back surface of 4 is in contact with the stopper 5, the flow path is wide open, and the fluid easily flows from left to right in the figure. The valve body 4 of the present embodiment having the convex portion 6 of the valve body abdomen is slightly smaller in flow passage area around the valve body than the conventional example, and the pressure loss ratio at the time of forward flow is about 1.2. That is, the resistance is increased by about 20%.

Next, the operation of the above configuration will be described.

In FIG. 1, when the normal flow that flows from the left to the right in the diagram changes to a reverse flow that flows from the right to the left in the diagram for some reason, the fluid force that has been pushing in the direction of opening the valve body 4 until now. Disappears, and conversely, a reverse flow fluid force for propelling the valve body 4 from the right to the left in the figure is applied, and the valve body 4 rotates clockwise around the hinge pin 8 in the figure to close the valve. At that time, in the conventional case, when the valve is closed, the valve body 4 collides with the valve seat 7 and the flow of the fluid stops instantaneously, so that a water hammer phenomenon occurs, and not only the valve but also various parts of the pipe system. In this embodiment, since the valve body abdominal surface convex portion 6 of the valve body 4 starts to be fitted into the valve seat 7 in the reverse flow, first, the peripheral cylinder inflow amount of the upper half of the valve body 4 (valve Abdominal convex part 6
(Flowing through the cylindrical gap between the outer circumference of the valve seat and the inner circumference of the valve seat 7) is reduced, and the flow rate reduction starts earlier than in the conventional example compared to the opening degree of the valve body 4. That is, the reduction of the fluid velocity to the right of the valve body 4 starts earlier than in the conventional example. Then, as the valve body 4 contracts with respect to the valve seat 7, the main flow depends on the flow passage cross-sectional area of the groove 6a, and the flow passage cutoff from the outer periphery of the conventional valve body 4 is caused. The fluid velocity is naturally controlled by the flow of the groove having the W width smaller than the area. However, the fluid velocity does not become 0 until the valve body 4 itself comes into contact (close contact) with the valve seat 4 as shown in FIG. Very small. At the stage when the valve element 4 is in contact with the valve seat 4, the flow velocity becomes 0 in the conventional example as well, but the fluid velocity at that moment is large for the reason described above. That is, compared with the conventional example, the fluid stopping speed of this embodiment is remarkably small, and therefore the water hammer is also small. Comparing this in the figure, in this embodiment, for example, the flow is as shown by the black arrow in FIGS. 1 and 3, and the flow rate reduction is started earlier in time with respect to the reverse flow.
Further, while the flow rate is sufficiently reduced, a small amount of water remains until the valve body 4 itself comes into close contact with the valve seat 7, so that water hammer does not occur. In the conventional example, however, a form as shown by a black arrow in FIG. The flow does not continue to be substantially reduced and the flow is suddenly stopped when the valve body 4 is in close contact with the valve seat 7, resulting in a large water hammer.

Further, in the present embodiment, even if the opening degree of the valve body 4 becomes small, as shown by the black arrow in FIG. Since it flows in from one groove 6a to the left, compared to the conventional example in which it flows from the entire outer periphery of the valve body 4 as shown in FIG. 7, periodic pressure fluctuations on the left side of the valve body 4 do not occur. No vibration or surging will occur.

As described above, according to this embodiment, the swing check valve is provided with the convex portion (protruding portion) 6 of the valve body on the valve seat 7 side of the valve body 4, and the groove 6a is formed in the lower portion thereof. Therefore, when the valve is closed due to backflow, the flow velocity reduction is started early, and the flow velocity is sufficiently reduced by the time the blockage is completed. It has the advantage of not causing water hammer damage.

Further, even if the opening degree of the valve body 4 becomes small, the groove 6
Since the bottom part of a is provided so as to be gradually shallower from the lower edge toward the center of the valve body 4, the flow subtending between the valve body 4 and the valve seat 7 passes exclusively through the groove 6a, and the flow is Four
The minute backflow is formed along the valve body 4 only from one side, not from the entire outer circumference, and there is an advantage that the valve body 4 and the like, and hence the valve, does not vibrate.

[0027]

Since the present invention is constructed as described above, it has the following effects.

That is, according to the present invention, the protrusion provided on the valve seat side of the valve body does not obstruct the flow at the time of forward flow, and reduces the inflow amount that passes through the valve body at the time of reverse flow to reduce the valve closing speed. Since it slows down, the water hammer that occurs when the valve is closed is eliminated or mitigated, and the occurrence of damage to the valve and other elements due to the water hammer is prevented.

Further, the groove provided on the above-mentioned protrusion eliminates the flow-through of the flow from the outer periphery of the valve body and eliminates the occurrence of valve vibration when the valve is closed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a swing check valve according to an embodiment of the present invention,

2 is a detailed view of the valve body 4 and the like in FIG. 1, (a) is a side sectional view, (b) is a front view of the valve body 4, (c) is a perspective view of (b), FIG.

FIG. 3 is a schematic diagram showing a state of the valve body of the above-described embodiment during reverse flow of an intermediate opening degree;

FIG. 4 is a schematic view showing a fully opened state of the valve body of the above embodiment,

FIG. 5 is a schematic view showing a fully closed state of the valve body of the above embodiment,

FIG. 6 is a vertical sectional view of a conventional example,

FIG. 7 is a schematic view showing a flow in the vicinity of a valve body at the time of reverse flow in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve casing 1a Opening cylinder part 2 Valve lid 3 Arm 4 Valve body 5 Stopper 6 Valve body abdominal convex part 6a Groove 7 Valve seat 8 Hinge pin

Claims (1)

[Claims] 1. A swing check valve in which a valve seat sealing valve body is provided on the valve seat side of an arm rotatably suspended by a substantially horizontal hinge inside a valve housing, and a valve of the valve body is provided. It is characterized in that it is provided with a projecting portion projectingly provided on the seat side so as to be capable of being fitted into the inner circumference of the valve seat, and a groove provided so as to be gradually shallowed from the lower outer edge of the projecting portion toward the center. Swing check valve.