JPH07293722A - Check valve - Google Patents

Abstract

PURPOSE:To increase the capacity for checking the reverse flow by increasing the pressing force against a valve seat of a valve disk by the hydrostatic pres sure of the fluid flowing in the reverse direction. CONSTITUTION:Valve seats 21, 22 where a valve disk 3 is abutted so that the seal line to prevent the passage of the fluid flowing in the reverse direction may be formed double are formed double, and a communicating port piping 66 to communicate a clearance part 23 to be demarcated between these double valve seats 21, 22 with a part whose pressure is lower than the fluid pressure on the lower pressure side of this valve is provided. An automatic opening/ closing valve 64 is provided in a communicating port piping 65, and the hydrostatic pressure of the fluid on the inlet side 1a and the outlet side 1b of this valve is detected by a pressure sensor 78, and when the hydrostatic pressure on the outlet side 1b is higher than that on the inlet side 1b, the automatic opening/closing valve 64 is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a check valve provided in various piping systems and the like so as to prevent the reverse flow of fluid.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional check valve, (A) is a view of the inside as viewed from above, (B) is a longitudinal sectional view in a valve closed state,
(C) is a vertical cross-sectional view of the valve open state. A valve seat 2 is formed in a valve box 1 that forms a fluid flow path in the valve, and a valve body 3 that is rotated about an axis 5 by an arm 4 is provided so as to contact the valve seat 2. . A lid 8 is airtightly attached to the upper surface of the valve. In the case of a forward flow in which the fluid flows from the left to the right in the figure, the pressure of the fluid pushes the valve element 3 to the right as shown in FIG. 3C, so that the valve element 3 rotates counterclockwise about the shaft 5. When it is rotated to, the flow path is opened away from the valve seat 2 and the fluid flows. In the case of a reverse flow in which the fluid tries to flow from the right to the left in the figure, as shown in FIG. 3B, the valve body 3 abuts the valve seat 2 due to its own weight to close the flow path, and Due to the pressure of the fluid that pushes the valve body 3 to the left, the valve body 3 strongly abuts the valve seat 2 and the backflow is blocked.

[0003]

The conventional check valve is as described above, and when the backflow is blocked, the valve body 3 has a valve seat due to the pressing force due to its weight and the pressure of the fluid to be backflowed. It is pressed against 2, and the larger the pressing force is, the higher the backflow blocking capability is. However, if the pressing force due to the weight of the valve body 3 is increased, the flow resistance at the time of forward flow increases, which is unsatisfactory. Therefore, there has been a problem in that the pressing force due to the static pressure of the fluid that tries to backflow is further increased to enhance the backflow blocking ability.

The present invention has been made in order to solve the above-mentioned problems, and the valve body 3 due to the hydrostatic pressure of the reverse flow is generated.
It is an object of the present invention to obtain a check valve in which the force of pressing the valve seat 2 against the valve seat 2 is made larger than that in the prior art to improve the backflow preventing ability.

[0005]

In the check valve according to the present invention, valve seats against which valve elements abut are formed so as to overlap so as to form seal lines for preventing the passage of backflow fluid in an overlapping manner. A communication hole pipe system is provided for communicating the space defined by the overlapping valve seats with a portion having a pressure lower than the fluid pressure on the low pressure side of the valve. Also, the communication hole pipe system can be opened and closed,
The fluid static pressures on the upstream side and the downstream side in the forward flow of the valve are detected, and when the downstream static pressure is higher than the upstream static pressure, the communication hole pipe system is opened.

[0006]

The valve seats of the check valve according to the present invention are formed in an overlapping manner, and the seal lines are also formed in an overlapping manner when the valve bodies come into contact with each other. Since there is a communication hole tubing system that communicates with a location lower in pressure than the fluid pressure on the low-pressure side, when the valve is closed, the pressure in this void becomes lower than the fluid pressure on the low-pressure side of this valve and attempts to flow backward. The pressure difference from the fluid pressure becomes large, the force pressing the valve body against the valve seat becomes strong, and the backflow prevention capability becomes high.
Further, if the communication hole pipe system can be opened and closed, and the communication hole pipe system is opened when the downstream side static pressure is higher than the upstream side static pressure, the pressure in the void becomes low at the time of reverse flow and the valve body is opened. The force that presses against the valve seat becomes stronger, and the backflow prevention capability becomes higher. By closing the communication hole pipe system at the time of forward flow, the fluid does not wastefully flow out from this communication hole pipe system.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A shows a check valve according to an embodiment of the present invention, FIG. 1A shows a reverse flow closed state, FIG. 1B shows a forward flow open state, and FIG. 1C shows a valve seat portion as seen from inside the valve. In the figure, 1 is a valve box, and inside the valve box 1 are an inlet 1a, an outlet 1b, and
A required fluid flow path such as the valve inner chamber 1c is formed, and a lid 8 is attached to the upper opening of the valve box 1 so as to seal the inside of the valve box 1. A large-diameter valve seat 21 and a small-diameter valve seat 2 which are concentrically overlapped with each other are formed at a connection portion between the inlet 1a and the valve inner chamber 1c.
Two are provided. A shaft 5 is attached above the valve seat in the valve box 1, an arm 4 is rotatably attached to the shaft 5, and a valve element 3 is fixed to the arm 4. Disc 3
As shown in FIG. 1 (A), the large-diameter valve seat 21 and the small-diameter valve seat 22 are simultaneously abutted, and the large-diameter valve seat 21 and the small-diameter valve seat 22 are
It is precisely formed so that endless seal lines are concentrically overlapped and formed in close contact with each other without any cuts or gaps.

As shown in FIG. 1A, when the valve is closed,
An annular gap 2 is formed between two concentric seal lines formed by the valve body 3 contacting the large-diameter valve seat 21 and the small-diameter valve seat 22.
3 is formed, but the communication hole 6 communicating with the void portion 23 is formed.
6 is provided in the valve box 1, and the automatic opening / closing valve 64 is provided in the communication hole 66.
A communication pipe system 65 having a is connected and connected. The other end of the communication pipe system 65 is communicated with a low pressure side tank (not shown) of a fluid system to which the check valve is applied. If the fluid in the pipe system can be released into the atmosphere, the communication pipe system 65 may be omitted and the fluid may be directly released into the atmosphere from the communication hole 66.

As shown in FIG. 1, the lid 8 is provided with a pressure detection hole 77 communicating with the valve inner chamber 1c, and a pressure sensor 78 for detecting the pressure in the valve inner chamber 1c is provided. Further, a signal line 79 for sending an opening / closing signal from the pressure sensor 78 to the automatic opening / closing valve 64 is provided. The pressure sensor 78 has an inlet 1a.
An unillustrated pressure detection conduit communicating with the flow path on the side of the inlet is connected to the static pressure of the fluid in the conduit on the side of the inlet 1a and the inner chamber 1c of the valve.
It is designed to compare with the static pressure of the fluid inside. Entrance 1
In order to prevent the influence of the dynamic pressure due to the difference in fluid flow velocity between the a side and the inside of the valve chamber 1c, the location where the pressure detection hole 77 is provided is a detection provided at the inlet 1a side rather than the lid 8. It is desirable to provide the hole on the side of the outlet 1b having the same diameter as the hole. This is to compare the static pressures by making the fluid flow velocities at both detection holes the same and making the dynamic pressures the same.

Next, the operation of this embodiment will be described. In the case of forward flow, as shown in FIG. 1 (B), the fluid enters from the inlet 1a and pushes the valve body 3 to the right in the figure, so that the valve body 3
Rotates counterclockwise around the axis 5 together with the arm 4 to open the flow path, and the fluid enters the valve inner chamber 1c from the inlet 1a and flows toward the outlet 1b. At this time, since the valve element 3 is heavy, due to the action of gravity, the valve element 3 tends to rotate clockwise about the shaft 5 to close the valve.
Some flow path resistance occurs. The tendency to close the valve due to this weight is necessary to prevent backflow, and if this tendency to close the valve is made smaller, there is the disadvantage that the tendency to close the valve at the time of backflow, which will be described later, also becomes smaller. However, if the valve closing tendency due to the weight is increased, there is a disadvantage that the flow path resistance during forward flow increases.

In the case of reverse flow, as shown in FIG.
Since the fluid tries to flow from the outlet 1b into the valve inner chamber 1c to the inlet 1a, the valve body 3 is pushed from the right side to the left side in the drawing. Axis 5
As described above, the valve body 3 suspended in the state has a valve closing tendency as shown in FIG. 1 (A) even when it is left standing by the action of gravity, and a fluid pressure from right to left is applied to this. Therefore, the valve body 3 is further strongly pressed so as to simultaneously contact the large-diameter valve seat 21 and the small-diameter valve seat 22, and the valve body 3 will flow backward due to the seal line that abuts the large-diameter valve seat 21 and the small-diameter valve seat 22. The passage of the fluid is blocked.

In this backflow prevention state, the pressure sensor 78 shown in FIG. 1 (A) has a static fluid pressure on the inlet 1a side and an outlet 1a.
Although it is compared with the fluid static pressure on the b side, if it is detected that the fluid static pressure on the outlet 1b side is greater than the fluid static pressure on the inlet 1a side, that is, if a reverse flow is about to occur, the automatic opening / closing valve A signal is output to open 64. When the automatic opening / closing valve 64 is opened, the void portion 23 communicates with the tank on the low pressure side and the pressure Pd is lower than the pressure Pa at the inlet 1a. Therefore, as shown in FIG. 2 (A), the small-diameter valve seat 22
Within the range, the differential pressure (Pb) obtained by subtracting the fluid pressure Pa on the left side of the valve body 3 from the reverse flow pressure Pb applied from the right side of the valve body 3.
-Pa) is applied, but in the range of the annular void portion 23, a large pressure, that is, a differential pressure (Pb-Pd) obtained by subtracting the low pressure Pd of the tank on the low pressure side from the backflow pressure Pb is applied. This large pressure presses the valve element 3 against the large-diameter valve seat 21 and the small-diameter valve seat 22 to prevent the backflow fluid from passing therethrough. In the conventional check valve shown in FIG. 2B, the closing pressure is the differential pressure (Pb−Pa) obtained by subtracting the left side fluid pressure Pa from the backflow pressure Pb from the right side. As shown in (A), a large differential pressure (Pb-Pd) is applied in the range of the void portion 23, and the valve closing force, that is, the backflow prevention capability is improved.

In FIG. 1, the outlet 1 is in the forward flow.
Since the fluid static pressure on the b side is not greater than the fluid static pressure on the inlet 1a side, the automatic opening / closing valve 64 is closed by the signal from the pressure sensor 78, and the fluid is prevented from being wastefully discharged from the communication hole 66. To be done. However, when the automatic opening / closing valve 64, the pressure sensor 78 and the like are not provided and the communication hole 66 is opened to the atmosphere, or when the communication pipe system 65 is connected to a low pressure tank or the like, the fluid flows out through the communication hole 66 during forward flow. Therefore, the diameters of the communication holes 66 and the communication pipe system 65 are preferably made as small as possible in order to reduce the loss during forward flow. Communication hole 6
6. Even if the communication pipe system 65 has a small diameter, it is sufficient to reduce the pressure in the void 23 at the time of reverse flow.

In the embodiment described above, the large-diameter valve seat 21 and the small-diameter valve seat 22 are formed so as to form two sealing lines.
However, three or more valve seats may be provided. Further, although the swing check valve has been described in the above embodiments, the lift check valve in which the valve element moves linearly against the gravity direction or the spring force also has the same valve seat. Similar effects can be obtained by applying the configuration of the present invention in which the seal lines are formed redundantly and holes are formed in the valve box so as to release the pressure in the gap between the seal lines.

[0015]

As described above, according to the present invention, the valve seats are formed in an overlapping manner so that the seal lines are formed in an overlapping manner, and the space between the seal lines is communicated with the low pressure portion. Therefore, at the time of reverse flow, a large differential pressure of the fluid is applied to the valve element in the range of the void, the valve closing force is increased, and the reverse flow blocking capability is improved.

[Brief description of drawings]

FIG. 1 shows a check valve according to an embodiment of the present invention,
(A) is a vertical cross-sectional view showing a state during reverse flow, (B) is a vertical cross-sectional view showing a state during forward flow, and (C) is a view of the valve seat portion seen from inside the valve.

FIG. 2 is a view showing a check valve's backflow prevention action, FIG. 2 (A) is a view showing the action of the check valve according to one embodiment of the present invention, and FIG.
[Fig. 6] is a view showing the action of a conventional check valve.

3A and 3B show a conventional check valve; FIG. 3A is a view of the inside as viewed from above, FIG. 3B is a vertical sectional view in a valve closed state, and FIG. 3C is a vertical sectional view in a valve open state.

[Explanation of Codes] 1: Valve box, 1a: Inlet, 1b: Outlet, 21: Large diameter valve seat, 22: Small diameter valve seat, 23: Void portion, 3: Valve body,
4: Arm, 5: Shaft, 64: Automatic open / close valve, 65: Communication pipe system, 66: Communication hole, 77: Pressure detection hole, 78: Pressure sensor, 79: Signal line.

Claims (2)

[Claims] 1. A valve seat with which a valve element abuts is formed in an overlapping manner so that a seal line for preventing passage of a backflow fluid is formed in an overlapping manner, and a void portion defined between the overlapping valve seats is formed. A non-return valve characterized in that a communication hole pipe system is provided for communicating with a portion having a pressure lower than the fluid pressure on the low pressure side of the valve. 2. A valve seat with which a valve element abuts is formed in an overlapping manner so that a seal line for preventing passage of a backflow fluid is formed in an overlapping manner, and a void portion defined between the overlapping valve seats is formed. A communication hole pipe system that opens and closes is connected to a location at a pressure lower than the low-pressure side fluid pressure of this valve, and the upstream and downstream fluid static pressures in the forward flow of this valve are detected to determine the downstream static pressure to the upstream static pressure. A check valve characterized in that the communication hole pipe system is opened when the pressure is higher than the pressure.