JPS60211173A - Quick-close nonreturn valve with slow-close auxiliary valve - Google Patents

Abstract

PURPOSE:To prevent the generation of water-hammering at the time of closing a valve by inserting a piston to which fluid resistance is applied in an auxiliary valve box mounted on the side of a main valve. CONSTITUTION:When the driving force of a pump is intercepted, a main valve body is fully opened. An auxiliary valve body 9 is also lowered by fluid force produced by a bsckward flow and spring force of a closed spring 11. Though in order to lower the auxiliary valve body 9, piston 18 coupled thereto has to be lowered at the same time, water flows out A chamber through a gap between a shaft hole 17 and an auxiliary valve shaft 8, so that the piston 18 and the auxiliary valve body 9 are slowly lowered. As the shaft diameter of the auxiliary valve shaft 8 advancing into the shaft hole 17 is gradually increased, the lowering of the auxiliary valve body 9 becomes further slower near the fully- closed condition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a quick-closing check valve with a slow-closing sub-valve that prevents water hammer when a pump is stopped.

When a pump pumping water suddenly has its driving power cut off due to a power outage or other reason, with a normal check valve, a large backflow occurs and then the valve closes abruptly, causing water hammer. It is dangerous. 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: a quick-closing type and a slow-closing type. The quick-closing type is mainly used for small and medium diameter pumps, and the slow closing type is mainly used for large and medium c'J diameter pump equipment. A quick-closing check valve applies a closing force such as a spring force to the valve body to quickly close the valve before the backflow becomes large, reducing water hammer.

This method is not effective unless the closing force of the valve is increased, so the valve resistance increases. Furthermore, even if it could ideally be closed without delay, as is well known from hydraulics,
The pressure head rises to the value added to the actual head by subtracting the pressure head just before the invert valve closes from the actual head, so if the pipeline is long, the pressure increase due to this will be large. .

In addition to the main valve through which most of the flow passes, a slow-closing check valve has two valves:
A sub-valve that is linked to the slow-closing device is provided, and the sub-valve that remains open relieves the pressure increase y1 when the main valve is closed due to backflow. This is a method of slowly closing the

In order to realize this method, conventional slow-closing check valves
The swing-type main valve that opens and closes the water inlet is attached to the valve stem so that it can swing freely, and the sub-valve that opens and closes the relatively large diameter water hole provided in a part of the main valve body is fixed to the valve stem. However, one end of the valve shaft passes through the valve box and is connected to a large hydraulic dashpot mounted outside the valve box.

In this structure, the main valve is closed by backflow, so even if the auxiliary valve diameter is relatively large, water hammer cannot be completely prevented when the main valve is closed. Furthermore, since the auxiliary valve diameter is large, the water hammer when the auxiliary valve is fully closed is very large, and the backflow amount until the auxiliary valve is fully closed is also large. Furthermore, since the auxiliary valve diameter is large, it is necessary to install a large hydraulic dashpot outside the valve box. For this reason, the loosening/closing mechanism becomes complicated and the check valve becomes very expensive.

Furthermore, since the hydraulic dashpot 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 movement of the sub-valve becomes uncertain due to increased friction, and in some cases, the sub-valve remains fully open even after the pump has stopped, causing backflow for a long period of time, causing the check to stop. (It will not fulfill the function of f.

In order to eliminate the above-mentioned drawbacks, the present invention aims to provide an ideal water hammer prevention check valve that is inexpensive, highly reliable, and has an extremely simple structure that completely eliminates the occurrence of water hammer when the valve is closed. That is. In order to achieve this purpose, an auxiliary valve box 5 having a cylinder 15 is attached to the back side of the main valve l, and the auxiliary valve box 5 has a piston 18 that slides on the inner surface of the cylinder.
A sub-valve shaft 8 for fixing the and sub-valve 9 is installed inside, and the piston 18
A gap 17 or a small hole 20 is provided that communicates with the A chamber formed between the cylinder bottom 16 and the cylinder bottom 16, and a water receiving plate 6 with one end fixed to the front side of the main valve body l is roughly provided at the tip of the sub-valve shaft 8. The configuration is such that they are in contact with each other. Examples thereof will be explained below with reference to the drawings.

FIG. 1 is a view of a first embodiment of a quick-closing check valve with a slow-closing sub-valve according to the present invention, viewed from the back side of a main valve body, and FIG. 2 is a longitudinal cross-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 piece 2 is loosely fitted to a main valve shaft 4 inserted through the side wall of a valve box 3 inserted between the flanges. There is. The outer periphery of the main valve body has a hollow tunnel cross-sectional shape so that the opening area of the main valve and the valve opening angle when fully opened can be increased. From the center of the main valve body l toward the tip,
A sub-valve box 5 containing a slow-closing sub-valve device is attached to the back side of the main valve body l. The slow-closing sub-valve device will be described in detail later. 6 is a water receiving plate that receives the force of the water flow when the pump is pumping water and the main valve body l is open; one end 7 is fixed near the main valve shaft on the front side of the main valve body, and the other end is fixed to the main valve shaft. Pull it away from the valve body 1 and lightly touch the tip of the sub-valve shaft 8.

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 l. For large diameter check valves, the fixed end 7 to the main valve body 1
and the water receiving plate 6 are connected by a hinge, and a stopper for the water receiving plate 6 is provided on the main valve body l so that the water receiving plate 6 does not separate from the tip of the sub-valve shaft 8 while water pumping is stopped.

The action of the water receiving plate 6 is that when the pump pumps water and the main valve body 1 is open, the water receiving plate 6 is pushed toward the main valve body 1 by the flow of water along the arrow in FIG. Therefore, the sub-valve shaft 8 that is in contact with it is pushed up, and the sub-valve 9 is fully opened.

IO is a double-wound torsion coil spring, which is fitted onto the main valve shaft 4, and whose ends are locked to the side wall of the valve box 3 and the main valve body 1;
They are arranged symmetrically with respect to the center of the main valve shaft 4, and are attached so as to bias the main valve body l in the closing direction. A check valve with a slow-closing sub-valve requires less closing force on the main valve than a quick-closing check valve, and also has a torsion coil spring.
The loss head of the valve can be reduced by making the spring constant smaller by making the spring 0 double-wound, and by increasing the opening angle of the main valve body 1 during water pumping. Furthermore, by making the coil spring 10 double-wound, the part of the end that engages the main valve element l and the part that engages the valve body 1 to the side wall of the box 3 are oriented in the axial direction of the coil. Since the coil spring 10 can be brought close to each other, it can be easily attached to the main valve shaft 4 by twisting the coil spring 10 and then tightening the image portion. In addition, the water supply pipe with a check valve is long and has a large diameter.
When installing a check valve, if the pipe is vertical and flows upward, by installing a slow-closing sub-valve, water hammer can be prevented even if the biasing force of the main valve body 1 is as small as the self-weight of the main valve body l. Therefore, in this case, the torsion coil spring 10 can be omitted.

FIG. 3 shows a detailed longitudinal sectional view of the slow-closing sub-valve device. 5 is a sub-valve box with a sub-valve body 9 inside. Sub-valve shaft 8, closing spring 11
is included. The base portion 12 of the sub-valve box 5 is fixed to the main valve body l by screwing. In the case of a large diameter, the base should be flange-shaped and bolted to the main valve body l. A water passage hole 13 is provided inside the base portion 12, and a formula 14 is provided on the side wall of the portion where the sub-valve body 9 is accommodated, immediately above the base portion 12. When the sub-valve body 9 rises to open the valve, a small amount of fluid flows into the water passage hole 13. while the main valve l is open. It flows from the bottom to the top through the side hole 14, and after the pump power is cut off and the main valve l is closed, a large amount of fluid flows back through the water hole 13 from the top to the bottom.

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

A gasket 19 is attached to the outer periphery of the piston 18 to prevent leakage. The packing 19 is made of rubber or Teflon, and must have as little friction as possible to completely stop leakage. Since the secondary tj 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 clearance 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 thick when the auxiliary valve body 9 is fully opened, and when the auxiliary valve body 9 is lowered and closed. The clearance becomes smaller as the valve is opened, and is gradually increased so that it becomes almost zero in the fully open state.Furthermore, instead of gradually changing the shaft diameter of the sub-valve shaft 8, a part of the circumference may be cut off. The closing spring 11 is a pushing spring with a weak spring force that is housed between the sub-valve body 9 and the cylinder bottom 16.When the sub-valve body 9 is open, that is, the sub-valve body 9 and the piston 18 push upward. When the pump stops pumping water and the main valve body l is closed, a backflow occurs immediately, and it flows downward from around the subvalve box through the water passage hole 13 in Example 14. The sub-valve body 9 is pulled downward by this backflow water and starts to close, but if the actual lift of the pump is small or the friction of the seal 19 is large, the closing stroke of the sub-valve body 9 will be delayed. becomes uncertain, and sometimes it is predicted that the sub-valve body 9 will not be fully closed.Therefore, after the main valve body l is closed, the sub-valve body 9
In order to ensure closure, a closing spring 11 with a weak spring force that overcomes the friction of the seal 19 is installed, but this is unnecessary if the actual lift of the pump is large and the friction of the seal 19 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 element 1 and the sub-valve element 9 are in the closed state, the main valve element 1 overcomes the biasing force of the double-wound torsion coil spring 10 in the closing direction due to water pressure and begins to open. . When the main valve body l opens, the water discharged from the pump flows along the front side of the main tf body l in the direction of the arrow in Figure 2. The free end side of the water plate is pushed by the water flow and pushes up the sub-valve shaft 8, pushing up the sub-valve body 9 and screw I/N 18 attached to the sub-valve shaft 8, and 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. In addition, part of the pumped water is generated by fully opening the sub-valve at water passage hole 13. Since it can pass through the side hole 14, the main valve element 1 is fully closed before the flow rate decreases to zero. If the 41 force in the closing direction is applied to the main valve body l in this way, even if the sub valve diameter is quite small,
The main valve can be closed before backflow begins. Therefore, since no backflow occurs when the main valve body l is closed, water hammer does not occur at all. Next, when the pressure inside the pipe on the downstream side of the reverse I top 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 it from the subvalve, which has a reverse flow rate, the occurrence of water hammer is prevented. Completely preventable.

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 auxiliary valve is suddenly reduced, 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 is fully closed.

When the sub-valve body 9 is fully opened and its lift is maximum, the backflow flow is expressed by example equation 14. The water flows through 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 reverse flow and the spring force of the closing spring 11. However, in order for the sub-valve body 9 to descend, the piston 1 connected to it must
8 must also descend at the same time, but for this the water in chamber A formed between the piston 18 and the cylinder bottom 16 must flow out. A gasket 19 is attached around the piston 18, and there is no leakage from this, so in order for the water in chamber A to flow out, it must pass through the shaft hole 17. Since it is penetrated, water flows out from the A chamber through the gap between the two, and the piston 18 and the sub-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 gap between the shaft hole 17 and the sub-valve shaft 8 acts as resistance and slows down the downward movement of the sub-valve body 9. This water becomes a buffer solution. Furthermore, as the piston 18 descends, the shaft diameter of the sub-valve shaft 8 that enters the shaft hole 17 gradually increases.
The gap between the two becomes smaller as a result, and becomes almost zero when it is close to being fully closed. Therefore, the descent of the sub-valve body 9 is as follows:
It gradually becomes noticeably slower and finally reaches full throttle. 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. Note that the fluid force acting on the sub-valve body 9 increases significantly when it approaches full opening, but the gap between the dual sub-valve shafts 8 and the shaft hole 17 is gradually reduced as the sub-valve body closes. Since this gap is almost zero when fully closed, the rate of decrease in flow rate near when fully closed 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 attached to the sub-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.

When the sub-valve body 9 is pushed up and the sub-valve is fully opened, the sub-valve shaft 8
The piston connected to the sub-valve body 9 via the piston is simultaneously pushed up, and the water in the A chamber is forced out through the small hole 20 provided in the piston 18. When the pump driving force is cut off, the main valve is closed, and backflow starts, the sub-valve body 9 and piston 18 are pushed down by the fluid force caused by the backflow and the spring force of the closing spring 11 provided to the A chamber. However, in order for these forces to move downward or 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 slowly descend.
Fully closed without 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. Further, the small hole 2o may be provided in the cylinder bottom 16 instead of being provided in the piston 18.

Figure 5 shows a third embodiment in which a slow-closing lift-type sub-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, and 23 is a main valve shaft. support, 2
4 is a 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.

As described above, according to the quick-closing check valve with a slow-closing sub-valve according to the present invention, a slow-closing sub-valve device with a simple structure and small size that uses water passing through the check valve as a buffer liquid can be used as a main valve. It has a simple structure that just requires attaching the water receiving plate to the front side of the main valve body to fully open the sub valve.It prevents water hammer when the main valve is closed and prevents the sub valve from opening. operation can be ensured. In addition, by applying a spring force with a small spring constant in the closing direction of the main valve, it is possible to close the main valve before the backflow starts, completely preventing water hammer when the main valve is closed, and when pumping water, the main valve can be closed before the backflow starts. The valve can be easily fully opened, and the auxiliary valve diameter can be made significantly smaller than the main valve diameter, which has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a view of a check valve with a slow-closing auxiliary valve according to a first embodiment of the present invention, seen from the back side of the main valve body, Fig. 2 is a longitudinal cross-sectional view of Fig. Fig. 4 is a detailed longitudinal sectional view of the slow-closing sub-valve device in Fig. 2, Fig. 4 is a second embodiment of the slow-closing sub-valve device, and Fig. 5 is a check valve with a slow-closing sub-valve of the third embodiment. FIG. 1... Main valve body, 3... 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. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A sub-valve box 5 having a cylinder 15 is attached to the back side of the main valve 1, and a sub-valve shaft 8 for fixing a piston 18 sliding on the inner surface of the cylinder and a sub-valve 9 is installed inside the sub-valve box 5. A gap 17 or a small hole 20 is provided that communicates with the A chamber formed between the piston 18 and the cylinder bottom 16, and a water receiving plate 6 is provided at the tip of the sub-valve shaft 8 with one end fixed to the front side of the main valve body l. A quick-closing check valve with a slow-closing auxiliary valve 4=I in contact with the valve.