JPH0247334Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a check valve with a bypass valve.When the backflow is stopped or the backflow is extremely small, the bypass valve relates to a bypass valve type check valve which is configured to self-close.

BACKGROUND ART FIG. 5 is a side sectional view showing the structure of a conventional check valve with a bypass valve, in which 10 is a main valve portion, 2
0 indicates the bypass valve mechanism portion. The main valve body 1 is rotatably installed in the main valve chamber 2 by a valve stem 3, and is closed when there is a reverse flow as indicated by R, and when there is a forward flow as indicated by F, it is indicated by a two-dot chain line 1'. The valve opens like this. 9 indicates a stopper. When the main valve body 1 opens and the differential pressure between the inside and outside of the valve disappears, the bypass valve 21 in the bypass valve chamber 22 is pulled upward by the spring 35 attached to the tip of the valve stem 23, and the two-point parallel line 21 ’ and the valve is opened. When the pump stops, etc., the main valve suddenly closes due to backflow, but since the bypass valve is open, the impact and pressure increase when the main valve closes is small. Therefore, whenever the main valve is open, the bypass valve must also be open. After the main valve is closed, the bypass valve 21 is pushed down by the backflow R and the bypass valve is closed. A piston 24 attached to the bypass valve stem 23 moves up and down in the hydraulic cylinder 28, and when the bypass valve 21 is in the open position at the upper dashed line 21', the piston 24 is at the upper dashed line 24'. It is in. When the bypass valve 21 is pushed down in the closing direction by the backflow R, the piston 24 also descends in the hydraulic cylinder 28, the oil below the piston is compressed and flows above the piston through the needle valve 27, and the bypass valve is relaxed. Closed. Needle valve 27
When the valve is throttled down, the amount of oil flowing becomes smaller and the valve is closed more slowly. In the figure, 26 is a cover, and 36 is a drain hole. FIG. 6 is an enlarged explanatory view of the buffering effect of this oil. When the piston 24 descends in the hydraulic cylinder 28, the oil below the piston is compressed, enters the pipe 37, flows in the direction of arrow P, and flows through the needle valve 27. and flows above the piston 24. The more the needle valve 27 is throttled, the stronger the buffering effect becomes, and the lowering of the piston 24 becomes more gradual.

In this way, in conventional valve configurations, in order for the bypass valve to close, the force of the backflow pushing down on the bypass valve must overcome the force of the spring pulling up the bypass valve. Therefore, unless there is a large amount of backflow, the bypass valve will close. does not close, and the check valve has the disadvantage that it cannot prevent backflow if there is a small amount of backflow.

Also, if internal pressure is generated in the valve chamber of the check valve and the differential pressure across the main valve is low, the bypass valve will receive a force in the direction of opening due to the internal pressure, and the force of the spring will be added to it, causing the bypass valve to open. The disadvantage is that the valve remains open and does not close when a small amount of backflow occurs and cannot prevent backflow.

Means to solve the problem In this invention, the push-up rod of the bypass valve is attached via the hinge pin and link on the downstream side of the main valve body of the check valve, and when the main valve body opens, the bypass valve is pushed up by the push-up rod. The bypass valve is forcibly opened according to the degree of opening of the main valve, and when a backflow occurs and the main valve suddenly closes, the push-up rod also descends and the bypass valve closes due to the backflow. If a weight is attached to the bypass valve, the weight will cause the bypass valve to close by itself even if the backflow is extremely small.

Embodiment FIG. 1 is a side sectional view of an embodiment of the check valve with bypass valve of this invention, and FIG. It's summery. The main valve body 1 has a valve stem 3 inside the main valve box 2.
It is rotatably attached by. Arrow F
When the flow is normal as shown in , the main valve body 1 is open as shown by a two-dot chain line 1'. 9 is a stopper. Further, when the backflow R occurs, the main valve body 1 is in the closed position.

A mounting portion 4 is fixed on the downstream side surface of the main valve body 1,
A link 6 is rotatably attached via a hinge pin 5, and a push-up rod 8 is further attached via a hinge pin 7. The push-up rod 8 is guided by the vertical guide portion 31 and vertically moves up and down as the main valve body 1 opens and closes. Since the tip of the push-up rod 8 is in contact with the bypass valve 21 in the bypass valve chamber 22, the bypass valve 21 is forcibly opened according to the opening degree of the main valve body 1. A two-dot chain line 21' indicates the elevated position of the bypass valve 21.

A weight 25 is attached to the upper end of the bypass valve rod 23, and the piston 24 is attached within the hydraulic cylinder 28.
is installed. A dashed line 24' indicates the raised position of the piston 24 when the bypass valve is raised. 26 is a cover, 27 is a needle valve, 29
3 is a vent at the end of the bypass valve rod, and 32 is a seal and bearing portion of the bypass valve rod. In Figure 2, arc a
represents the rotation of the main valve body 1 around the valve stem 3, and the arc b represents the movement of the hinge pin 7. The actions of the needle valve 27 and the hydraulic cylinder 28 are as follows:
The piston 24 is similar to that explained in the figure.
The bypass valve is slowly closed by hydraulic pressure.

Both ends of the bypass valve rod 23 are open to the atmosphere, and the structure is such that no force is generated in the direction of opening the bypass valve due to internal pressure. Therefore, the weight 25 only needs to overcome the friction of the seal bearing 32 of the bypass valve rod 23, the sliding of the piston 24, the resistance of the oil throttle of the needle valve 27, etc., and when the push-up rod 8 descends, the bypass valve 25 can be lowered by its own weight, so even a small amount of backflow can close the bypass valve.

FIG. 3 shows another embodiment in which there are a plurality of main valve bodies (the figure shows a case of two), and FIG. 4 shows a view taken along the line A--A in FIG. 3.

In the figure, main valve bodies 51 and 61 are rotatably mounted in a main valve box 52 by valve stems 53 and 63, respectively. Two-dot chain lines 51' and 61' indicate the open positions of the main valve bodies 51 and 61, respectively.
The upper main valve body 51 is provided with a mounting portion 4, a hinge pin 5, a link 6, a hinge pin 7, and a push-up rod 8 in the same manner as in FIG. 1, and their functions are exactly the same.

A lever 71,
81 and a link 72 is attached to it, and each main valve body is opened and closed in conjunction with this link mechanism. Two-dot chain lines 51', 61', 71', 8
1', etc. respectively indicate the valve open position.

Effects This device has such a structure, and when the main valve body closes, the bypass valve can be closed by its own weight, so even a small amount of backflow can completely close the bypass valve. be able to.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of the first embodiment of this invention, Fig. 2 is an explanatory diagram of the link mechanism, Fig. 3 is a side sectional view of the second embodiment, and Fig. 4 is A-A in Fig. 3. An arrow view, FIG. 5 is a side sectional view of a conventional valve device, and FIG. 6 is an explanatory diagram of hydraulic damping action. Explanation of symbols, 1... Main valve body, 2... Main valve box, 3
... Valve stem, 4 ... Mounting part, 5 ... Hinge pin, 6
... Link, 7 ... Hinge pin, 8 ... Push-up rod, 9 ... Stopper, 21 ... Bypass valve, 2
2... Bypass valve chamber, 23... Bypass valve rod, 2
4...Piston, 25...Weight, 26...Cover, 27...Needle valve, 28...Hydraulic cylinder, 29...Vent, 31...Vertical guide, 32
... Seal/bearing part, 35 ... Spring, 36
...Drain hole, 37...Piping, 51,61...
Main valve body, 52... Main valve box, 53, 63... Valve stem,
71, 81... lever, 72... link.

Claims (1)

[Scope of claim for utility model registration] (1) A push-up rod of the bypass valve is provided via a link on the downstream side of the main valve body of the check valve, and when the main valve body opens during normal flow, this push-up rod Then,
The bypass valve is pushed upward to open, and when the main valve body closes during backflow, and the push-up rod descends, the bypass valve also descends due to the gravity of the attached weight and closes itself. Check valve with bypass valve. (2) The check valve with a bypass valve according to claim 1 of the utility model registration, wherein the upper and lower shaft ends of the bypass valve are open to atmospheric pressure.