JPH0219355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a quick-closing check valve with a slow-closing sub-valve that prevents water hammer when a pump is stopped.

(Problems to be solved by the prior art and the invention) When the pump driving force of a pump pumping water is suddenly cut off due to a power outage or other reasons, with a normal check valve, a large backflow occurs, and then the valve is shut off due to an impact. It is dangerous because water hammer may occur. There are various methods to prevent water hammer in this case, but among them, the method using a water hammer prevention check valve is the most widely used because it is simple. There are two types of pumps: quick-closing type and slow-closing type. The quick-closing type is mainly used for small and medium-sized pumps, and the slow-closing type is mainly used for large and medium-sized pump equipment.

Quick-closing check valves are equipped with a valve body in the valve body and apply a closing force such as a spring force to the valve body, so that after the pump stops pumping water, the water in the pipe starts flowing backwards. The valve body is quickly closed at the initial stage, that is, at a weak stage before the backflow becomes large, to reduce water hammer. If the valve body is suddenly closed when the backflow becomes large, water hammer will occur, so by closing the valve body as early as possible, water hammer can be kept as small as possible. .

However, in the case of this quick-closing check valve,
Since the valve body needs to close quickly, it is necessary to increase the closing force applied to the valve body, and increasing the closing force increases the valve resistance during water pumping, that is, the valve resistance during forward flow. A problem arises in which
Furthermore, even if it were ideally possible to close without delay,
As is well known in hydraulics, the pressure head rises to a value equal to the actual head plus the value obtained by subtracting the pressure head just before the check valve closes from the actual head. The pressure increase caused by this is quite large.

On the other hand, with a slow-closing check valve, a sub-valve is provided on the main valve body and the sub-valve is linked with a slow-closing device.
While the main valve body is closed by the reverse flow (no closing force such as spring force is applied to the main valve body),
The pressure increase caused by the closure of the main valve body is alleviated by the sub-valve, which remains open at that time, and then the sub-valve is closed slowly to prevent water hammer from occurring.

In order to realize this method, conventional slow-closing check valves have a swing-type main valve body that opens and closes the water inlet (main passage) attached to the valve stem so that it can swing freely. A sub-valve body that opens and closes a relatively large-diameter water hole provided in the valve body is fixed to the valve stem, and one end of the valve stem is connected to a large hydraulic doss pot that passes through the valve body and is attached to the outside of the valve body. It has a connected structure.

However, with this structure, the main valve body closes rapidly due to the backflow after it becomes large, so even if the diameter of the sub-valve is increased, water hammer cannot be completely prevented when the main valve body is closed. Moreover, if the diameter of the secondary valve is increased, when the secondary valve is fully closed,
There is a problem that the water hammer there becomes very large, and in addition, there is a problem that the back flow until the sub-valve is fully closed becomes large.In addition, because the sub-valve diameter is large, it is necessary to use a large hydraulic doss pot. It is necessary to install it outside the valve box.

Therefore, such a slow-closing check valve has a complicated slow-closing mechanism and is very expensive.

Furthermore, since the hydraulic doss pot is placed outside the valve body, friction and leakage at the point where the valve stem passes through the valve body become a problem. In other words, if the gasket is tightly tightened to reduce leakage, the increased friction will cause the sub-valve to function unreliably, and in some cases the sub-valve will remain fully open even after the pump has stopped, causing the valve to remain fully open for a long period of time. Backflow will occur and the check valve will no longer function properly.

(Means for Solving the Problems) The check valve of the present invention has been devised to solve the above problems, and its gist is as follows: (A) a main valve box, and (B) a check valve for preventing backflow. A unidirectional valve body for opening the main passage of water in the main valve box in the forward flow direction and closing it in the reverse flow direction, and is biased by the biasing means in the direction of closing the main passage. a main valve body; (C) a subvalve disposed in an opening formed in the main valve body; and (D) one end of an upstream surface of the main valve body fixed to the main valve body. and a swingable water receiving plate, and the sub-valve includes: (a) a sub-valve box attached to the main valve body; and (b) a sub-passage of water in the sub-valve box in the forward flow direction. (c) a cylinder fixed to the subvalve box; (d) a piston slidably fitted in the cylinder; (e) (f) a buffer chamber formed inside the cylinder by the piston; (g) a communication passage with a small passage area that communicates the inside and outside of the buffer chamber to allow water in the buffer chamber to move in and out by movement of a piston, and that causes flow resistance at that time; The free end side of the water receiving plate is brought into contact with the tip of the auxiliary valve shaft, and the auxiliary valve shaft receives the flow in the positive direction by the water receiving plate, and the auxiliary valve body is supported by the water receiving plate. The reason is that it is configured to be pushed in the opening direction.

(Operation and Effects of the Invention) As described above, the check valve of the present invention combines a conventional quick-closing check valve and a slow-closing check valve, and configures its main valve body as a quick-closing valve body. ,
On the other hand, this valve incorporates a sub-valve provided in a slow-closing check valve.

In other words, conventional quick-closing check valves have only a single valve body, which is biased in the closing direction by a spring force, while slow-closing check valves have a main valve body and a sub-valve. The main valve body is provided with a valve body, and no biasing force in the closing direction is applied to the main valve body, which is closed by the backflow of the pipe, and then the sub valve slowly closes to alleviate water hammer. However, in the present invention, the main valve body is configured as that of a conventional quick-closing type check valve, and the auxiliary valve is configured as a conventional slow-closing type auxiliary valve. This made it possible to completely eliminate water hammer when the pump stopped.

Specifically, in the check valve of the present invention, the main valve body is not closed by backflow in the pipe line, but by an urging force such as a spring force. Unlike conventional quick-closing check valves, the main valve body is closed when the water is flowing in the forward direction due to inertia after the pump has stopped, that is, before backflow begins. (because some of the water can pass through the auxiliary valve, which remains open). Therefore, occurrence of water hammer at that stage can be completely prevented.

In the check valve of the present invention, like the conventional slow-closing check valve, water hammer is prevented by slowly closing the auxiliary valve when backflow starts, but unlike the conventional slow-closing check valve, In this case, the main valve body suddenly closes after the backflow becomes large enough, and the secondary valve body closes slowly to compensate for the pressure increase at that time, mitigating the water hammer, so the diameter of the secondary valve is made considerably larger. I need to take it. On the other hand, in the check valve of the present invention,
As described above, since the main valve body can be closed before the backflow starts, even if the auxiliary valve has a small diameter, it is sufficiently effective to release the pressure increase caused by the closure of the main valve body and prevent water hammer. And because the diameter of the sub-valve is small, and the degree of backflow when the sub-valve closes is not large, unlike conventional slow-closing check valves, water hammer occurs when the sub-valve is closed. There is no such thing at all. This is an effect brought about by combining a quick-closing check valve and a slow-closing check valve, which have exactly opposite functions.

Furthermore, by assembling the sub-valve to the main valve body, the main valve body can be closed while allowing water to escape from the sub-valve, so the force for biasing the main valve body in the closing direction is reduced from the conventional sudden force. It can be made weaker than that of a closed check valve, and if the urging force can be made weaker, the valve resistance during water pumping will also be smaller.

Furthermore, according to the present invention, since the buffer mechanism consisting of a cylinder, a piston, a buffer chamber, etc. can be arranged in the main valve box, the valve shaft can be extended outside through the main valve box and interlocked with the buffer device. Unlike the conventional slow-closing check valve, the structure is simple and the cost is low, and there is no problem of friction or leakage at the part where the valve stem passes through.

In addition, the check valve of the present invention includes a water receiving plate,
It has a feature not found in conventional check valves in that the water receiving plate receives the flow in the forward direction in the pipe and opens the sub-valve using the water receiving plate.

That is, in the check valve of the present invention, when water is flowing in the forward direction in the pipe, the water receiving plate receives this flow and pushes the valve shaft tip of the sub-valve, that is, the sub-valve body, in the opening direction.

In order for the secondary valve to perform its original function, it must be in an open state when backflow starts, and for this purpose the secondary valve body is always biased in the open direction with a spring. This is good when the lift is large, but when the lift is small, after the main valve closes when the pump stops, the sub-valve overcomes the biasing force of the spring due to backflow and cannot close, causing the sub-valve to open. This will cause leakage in the reverse direction.

On the other hand, in the present invention, the sub-valve body is forcibly opened by the water receiving plate by utilizing the positive flow in the pipe, so that the sub-valve body is biased in the opening direction as described above. There is no need for a spring for this purpose. Therefore, the sub-valve body can be reliably closed when backflow starts. Rather, in the present invention, it is possible to bias the auxiliary valve body in the closing direction, and in this way, the auxiliary valve can be closed more reliably in the event of backflow, and its original function as a check valve is impaired. can be completely prevented.

(Example) Next, an example of the present invention will be described in detail based on the drawings.

Fig. 1 is a view of the first embodiment of the quick-closing check valve with a slow-closing sub-valve of the present invention, viewed from the back side (downstream side) of the main valve body, and Fig. 2 is a longitudinal sectional view of the same figure. . 1 is a swing-type main valve body equipped with two mounting pieces 2, and the base of the mounting pieces 2 is a main valve box 3 inserted between the flanges.
It is loosely fitted to the main valve shaft 4 inserted through the side wall of the valve. The outer periphery of the main valve body has a substantially tunnel cross-sectional shape so that the opening area of the main valve and the valve opening angle when fully opened can be increased. A sub-valve box 5 containing a slow-closing sub-valve device is attached to the back side of the main valve body 1, closer to the tip than the center of the main valve body 1. The slow-closing sub-valve device will be described in detail later. 6
is a water receiving plate that receives force from the water flow when the pump is pumping water and the main valve body 1 is open, and one end 7 is fixed near the main valve shaft on the front side (upstream side) of the main valve body 1, The other end is separated from the main valve body 1 and the auxiliary valve shaft 8
Lightly touch the tip of the In a small-diameter check valve, the water receiving plate 6 is made entirely of a thin plate spring, and is bent near the fixed end attached to the main valve body 1. In a large-diameter check valve, the fixed end 7 to the main valve body 1 and the water receiving plate 6 are connected with a hinge, and the water receiving plate 6 is further prevented from separating from the tip of the sub-valve shaft 8 while pumping is stopped. , the main valve body 1 is provided with a stopper for the water receiving plate 6, etc.

The action of the water receiving plate 6 is that the pump pumps water and the main valve body 1
When the water receiving plate 6 is open, the flow of water along the arrow in FIG.
The sub-valve 9 is fully opened.

Reference numeral 10 denotes a double-wound torsion coil spring, which is fitted onto the main valve shaft 4, its ends are locked to the side wall of the main valve box 3 and the main valve body 1, and the center of the main valve shaft 4 is the boundary. They are arranged symmetrically and attached so as to bias the main valve body 1 in the closing direction. A check valve with a slow-closing auxiliary valve requires a considerably smaller closing force on the main valve than a quick-closing check valve, and furthermore, the torsion coil spring 10 is
By using a heavy winding, the spring constant can be reduced, and by increasing the opening angle of the main valve body 1 during water pumping, the loss head of the valve can be reduced. Furthermore, by making the coil spring 10 double-wound, the portion of the end portion that locks onto the main valve body 1 and the portion that locks onto the side wall of the main valve box 3 are close to each other in the axial direction of the coil. Since the coil spring 10 can be twisted, it can be easily attached to the main valve shaft 4 by tightening both parts. In addition, if the water supply pipe to which the check valve is installed is long and has a large diameter, and if the check valve is installed vertically and flows upward, the biasing force of the main valve body 1 can be reduced by installing a slow-closing sub-valve. Since water hammer can be prevented even with a value as small as the self-weight of the valve body 1, the torsion coil spring 10 can be omitted in this case. That is, the weight of the main valve body 1 can also be used as a biasing force.

FIG. 3 shows a detailed longitudinal sectional view of the slow-closing sub-valve device. Reference numeral 5 denotes a sub-valve box in which a sub-valve body 9, a sub-valve shaft 8 and a closing spring 11 are housed. The base portion 12 of the sub-valve box 5 is fixed to the main valve body 1 by screwing. In the case of a large diameter, the base portion 12 is flange-shaped and bolted to the main valve body 1. base 1
2, and a side hole 14 in the side wall of the part where the sub-valve body 9 is accommodated, just above the base part 12.
will be established. When the sub-valve body 9 rises to open the valve, a small amount of fluid flows into the water passage hole 1 while the main valve body 1 is open.
3. A large amount of fluid flows from the bottom to the top through the side hole 14, and after the pump power is cut off and the main valve body 1 is closed, a large amount of fluid flows from the top to the bottom through the side hole 14 and the water passage hole 13. flow backwards.

A cylinder 15 is attached to the upper part of the sub-valve box 5, and a shaft hole 17 is bored in the bottom 16 of the cylinder.
A sub-valve shaft 8 is attached to a piston 18 within the cylinder 15 through a shaft hole 17.

A gasket 19 is attached to the outer periphery of the piston 18 to prevent leakage. The gasket 19 is made of rubber or Teflon, and must have as little friction as possible to completely stop leakage. Since the auxiliary valve diameter is generally small, the packing 19 is also small, so the piston 18 and the packing 19 are usually made as one piece. The gap between the shaft hole 17 and the auxiliary valve shaft 8 is made so that the auxiliary valve shaft 8 is made thin so that it becomes large when the auxiliary valve body 9 is fully opened, and the auxiliary valve body 9 is lowered and closed. The gap becomes smaller, and the gap is gradually increased so that it becomes almost zero in the fully closed state. Moreover, instead of gradually changing the shaft diameter of the sub-valve shaft 8, a part of the circumference may be removed.

The closing spring 11 is a pressure spring with a weak spring force, which is housed between the sub-valve body 9 and the cylinder bottom 16. While the sub-valve body 9 is open, that is, the sub-valve body 9 and the piston 18
When the pump stops pumping water and the main valve body 1 is closed, a backflow occurs immediately from around the sub-valve box 3 to the side hole 1.
4. It flows downward through the water passage hole 13. Due to this backflow water, the sub-valve body 9 is pulled downward and starts to close, but if the actual lift of the pump is small or the friction of the seal 19 is large, the sub-valve body 9 The closing stroke becomes uncertain, and it is predicted that sometimes the sub-valve body 9 will not be fully closed. Therefore, in order to ensure that the sub-valve element 9 is closed after the main valve element 1 is closed, a closing spring 11 with a weak spring force that overcomes the friction of the gasket 19 is installed, but the actual lift of the pump is large and the friction of the gasket 19 is It is unnecessary if it is small.

Next, the operation of the quick-closing check valve with slow-closing sub-valve will be explained.

When the pump starts pumping water when both the main valve body 1 and the sub-valve body 9 are in the closed state, the main valve body 1 overcomes the urging force in the closing direction of the double-wound torsion coil spring 10 due to water pressure and opens. start. When the main valve body 1 opens, the water discharged from the pump flows through the main valve body 1.
Since the water flows in the direction of the arrow in FIG. 2 along the front side of the main valve body 1, a
The free end side of the sub-valve shaft 8 is pushed up by the water flow, and the sub-valve body 9 and piston 18 attached to the sub-valve shaft 8 are pushed up, so that the sub-valve is fully opened.

On the other hand, when the driving force of the pump is cut off, the amount of water pumped by the pump begins to decrease rapidly, but the biasing force of the double-wound torsion coil spring 10 is applied to the main valve body 1 to bias it in the closing direction. In addition, since a part of the pumped water can pass through the water passage hole 13 and the side hole 14 by fully opening the sub-valve, the main valve body 1 is fully closed before the flow rate decreases to zero. If the biasing force in the closing direction is applied to the main valve body 1 in this way, the main valve can be closed before the backflow starts even if the auxiliary valve diameter is quite small. Therefore, since no backflow occurs when the main valve body 1 is closed, water hammer does not occur at all. Next, when the pressure in the pipe on the downstream side of the check valve recovers to the pressure head of the actual head, the water in the pipe is compressed and begins to flow backwards, but by releasing this reverse flow from the subvalve, water hammer occurs. can be completely prevented.

Since the pressure difference between both sides of the main valve is large, the backflow amount passing through the sub-valve is large, although the sub-valve diameter is significantly smaller than the main valve diameter. Therefore, if the backflow flow through the sub-valve is suddenly reduced, the pressure will increase due to water hammer. In particular, it is necessary to reduce the rate of decrease in flow rate when the sub-valve body 9 is fully closed. When the sub-valve body 9 is fully opened and its lift is maximum, the backflow flow through the side hole 14 and the water passage hole 13 to the upstream side of the check valve. The sub-valve body 9 begins to descend due to the fluid force generated by this backflow and the spring force of the closing spring 11. However, in order for the sub-valve body 9 to descend, the piston 18 connected to it must also descend at the same time. Must. A gasket 19 is attached to the circumference of the piston 18, and there is no leakage from this, so water in the A chamber must pass through the shaft hole 17 in order to flow out. Since the auxiliary valve shaft 8 passes through the shaft hole 17, water flows out from the A chamber through the gap between the two, and the piston 18 and the auxiliary valve body 9 gradually descend accordingly. That is, when the water that has flowed into chamber A when the sub-valve body 9 is fully opened flows out again, the shaft hole 1
The gap between 7 and the auxiliary valve shaft 8 acts as resistance, and the auxiliary valve body 9
This water acts as a buffer because it slows down the downward movement of. As the piston 18 further descends,
Since the shaft diameter of the auxiliary valve shaft 8 entering the shaft hole 17 gradually becomes thicker, the gap between the two becomes smaller accordingly, and becomes almost zero when the valve is close to fully closed. Therefore, the descent of the sub-valve body 9 gradually becomes extremely gradual and finally reaches full closure. Therefore, no water hammer occurs when the sub-valve is closed. Further, since the sub-valve shaft 8 always reciprocates within the shaft hole 17 when the sub-valve opens and closes, there is no fear that the shaft hole will be blocked by dirt or the like. The fluid force acting on the sub-valve body 9 increases significantly as it approaches full closure, but the gap between the sub-valve shaft 8 and the shaft hole 17 described above is gradually reduced as the sub-valve body closes. Since this gap is set to almost zero when the valve is fully closed, the rate of decrease in flow rate near the fully closed position can be made extremely small.

FIG. 4 shows a second embodiment of the slow-closing sub-valve device in detail. Since the cylinder 15 is mounted with the auxiliary valve box 5 with the cylinder bottom 16 facing up, contrary to FIG. 3, the A chamber between the piston 18 and the cylinder bottom 16 is located above the piston 18. When the sub-valve body 9 is pushed up and the sub-valve is fully opened, the piston 18 connected to the sub-valve body 9 via the sub-valve shaft 8 is simultaneously pushed up, and the water in chamber A flows through the small hole 2 provided in the piston 18.
Pushed out through 0. When the pump driving force is cut off, the main valve body 1 is closed, and the backflow starts, the sub-valve body 9 and the piston 18 are pushed down by the fluid force caused by the backflow and the spring force of the closing spring 11 provided in the A chamber. It will be done. However, in order for these two forces to move downward, ie, in the closing direction, water must flow into chamber A through the small hole 20. Since there is a large resistance for water to pass through the small hole 20, the piston 18 and the sub-valve body 9 descend slowly and are fully closed without generating water hammer. When the sub-valve body 9 closes, the fluid force acting on the sub-valve body 9 is very large, so if the area of the piston 18 is not made larger than the area of the sub-valve body 9, a cavity phenomenon will occur in chamber A, causing the sub-valve body to close. Care must be taken that there is a risk that the valve body 9 will close in an impact. In addition, the small hole 20 is
Instead of being provided on the piston 18, it can also be provided on the cylinder bottom 16.

FIG. 5 shows a third embodiment in which a slow-closing lift-type auxiliary valve device is attached to a flange-type quick-closing lift valve.

21 is a lift type main valve body, 22 is a lift type main valve shaft, 23 is a main valve shaft support, 24 is a main valve box, and 25 is a compression coil spring. The opening/closing mechanism of the sub-valve body 9 is the same as that of the swing type main valve shown in FIGS. 1 and 2.

[Brief explanation of drawings]

Fig. 1 is a view of a quick-closing check valve with a slow-closing sub-valve according to the first embodiment of the present invention, viewed from the back side of the main valve body;
The figure is a longitudinal cross-sectional view of Figure 1, and Figure 3 is a cross-sectional view of Figure 1 and 2.
FIG. 4 is a vertical sectional view of a slow-closing auxiliary valve device according to another embodiment of the present invention, and FIG. It is a longitudinal cross-sectional view of a quick-closing check valve with a closing sub-valve. 1: Main valve body, 3: Main valve box, 6: Water receiving plate, 5: Sub-valve box, 8: Sub-valve shaft, 9: Sub-valve body, 10: Double-wound torsion coil spring, 11: Closing spring, 18: Piston.

Claims (1)

[Scope of Claims] 1 (A) A main valve box; (B) A unidirectional valve body for preventing backflow, which opens the main passage of water in the main valve box in the forward direction and the backflow direction. (C) a sub-valve disposed in an opening formed in the main valve body; (D) ) a swingable water receiving plate having one end fixed to the main valve body on the upstream side of the main valve body; a valve box; (b) a unidirectional sub-valve body that opens a sub-passage of water in the sub-valve box in the forward flow direction and closes it in the reverse flow direction; (c) a cylinder fixed to the sub-valve box; (d) a piston slidably fitted into the cylinder; (e) a buffer chamber formed inside the cylinder by the piston; (f) a piston that connects the piston and the sub-valve body; (g) a sub-valve shaft whose tip is projected upstream from the opening of the main valve body when the sub-valve body is closed; It is provided with a communication passageway with a small passageway area that causes flow resistance when moving in and out, and the free end side of the water receiving plate is in contact with the tip of the sub-valve shaft, A quick-closing check valve with a slow-closing sub-valve, characterized in that the sub-valve shaft is pushed in a direction to open the sub-valve body by a water receiving plate receiving a flow in a positive direction.