JP2003090448A - Check valve, duplex check valve using the same, pressure reducing type reverse flow preventing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce flow resistance of a check valve and improve reverse flow preventing capacity. SOLUTION: A valve seat A of the check valve is separated from a housing. A pressure sensitive disk movable to the housing is formed. A valve A is faced to the valve seat A and a valve element is energized. A stopper controlling movement of the valve element toward an outlet side is provided. The valve is opened by contact of the valve element to the stopper. The pressure sensitive disk sensing pressure difference and a valve opening and closing fluid are separated. Flow resistance and sealing force of the valve can be determined by combination of a diameter of the pressure sensitive disk and force energizing the valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a check valve which is attached to a pipe, a device or the like for supplying a fluid to prevent a backflow of the fluid. In particular, the present invention relates to a check valve for preventing backflow of a device directly connected to a pipe of tap water, a double check valve, and a decompression type backflow preventer used for a direct connection water supply device.

[0002]

2. Description of the Related Art A check valve in a fluid supply system, particularly a water supply system and a hot water supply system, is a valve that prevents a backflow that causes contamination of the entire water supply system and hot water supply system, and is one of the most important parts. As shown in FIG. 5, the conventional check valve has an inlet 7 and an outlet 8 of the housing A.
The valve seat 15 is formed in the flow path connecting the
The valve body 5 having a valve 18 made of an elastic body is attached to the valve seat 15 so as to be separably attached to the valve seat 15 at all times, and the fluid pressure of the fluid flowing from the inlet 7 and the outlet side When the force pushing the valve 18 due to the pressure difference with the fluid pressure exceeds the spring force, the valve is opened and the fluid flows out toward the outlet, and the force pushing the valve 18 due to the pressure difference is less than the spring force (the fluid pressure on the inlet side is If the pressure is lower than the fluid pressure on the outlet side), the valve is closed to stop the flow of fluid and prevent backflow.

Further, there is a double check valve as a valve for surely preventing backflow. As shown in FIG. 6, a conventional double check valve has two sets of the above-mentioned check valves, a first check valve 27 and a second check valve 28, which are installed in a flow path connecting the inlet 7 and the outlet 8 of the housing A. Is.

FIG. 12 shows a conventional decompression type backflow preventer. In the conventional decompression type backflow preventer, two sets of the above-mentioned check valves are installed as a first check valve 27 and a second check valve 28 in the flow path connecting the inlet 7 and the outlet 8 of the housing A, and the first check valve is installed. A primary chamber 25 between the inlet 7 and the first check valve 27 upstream of the valve 27, an intermediate chamber 11 between the first check valve 27 and the second check valve 28, a second check valve 28 and an outlet 8. The flow path is separated into the secondary chamber 12 between the two, and the diaphragm B29 that is movable by sensing the differential pressure between the primary chamber 25 and the intermediate chamber 11 is assembled in a watertight manner.
The second pressure chamber 33 communicating with the intermediate chamber 11 through the communication hole B39.
The valve C32 facing the valve seat C31 formed around the second pressure chamber side of the opening of the communication hole 30 that communicates with the external discharge port 41 is integrally formed, and the pressure of the primary chamber 25 is set to the intermediate chamber 11 When the pressure in the intermediate chamber 11 is higher than the pressure in the primary chamber 25, the valve C32 is in close contact with the valve seat C31 to close the valve. It is a device that opens to 41 and prevents backflow even if a leak occurs in the first check valve 27 and the second check valve 28.

[0005]

The check valve is required to have low flow resistance and high backflow prevention capability (sealing force). Flow resistance and sealing force of a conventional check valve are πR, where R is the valve diameter, F is the spring force, ΔP is the differential pressure, and r is the seal width of the valve.
^{2 When} ΔP / 4> F, the valve opens and flows, and the unit area sealing force of the valve becomes F / πRr. When R is increased, the flow resistance decreases but the sealing force decreases, and when F increases, the sealing force decreases. However, the flow resistance also increases, which conflicts. Therefore, the sealing force is determined within the allowable range of flow resistance.

Since the double check valve uses two sets of the above-mentioned check valves, it has the same problem. Also, the combination of the check valves having the same structure is highly likely to cause the same failure, and has the same structure. A combination of check valves is desired. The same applies to a decompression type backflow preventer using two sets of check valves. A double check valve having a combination of a check valve having a small flow resistance and a high check flow preventing ability and a check valve having a different structure has been desired.

[0007]

In a conventional check valve, a valve seat integrated with a housing is formed in a passage connecting an inlet and an outlet of the housing as shown in FIG. Then, the valve moves by sensing the pressure difference between the inlet pressure and the outlet pressure,
Since it closes and separates from the valve seat to open and close the fluid, the valve that opens and closes the fluid also functions as a pressure sensitive panel that senses the differential pressure.To reduce the flow resistance and increase the sealing force of the valve as described above. Result in conflicting results.

According to the present invention, a water chamber is formed in the flow path connecting the inlet and the outlet of the housing, and the water chamber is partitioned into an intermediate chamber and a secondary chamber in a watertight manner so as to be movable in the axial direction. A pressure-sensitive plate having a through hole communicating between the intermediate chamber and the secondary chamber is installed at a part, and a valve seat A is formed around the intermediate chamber side of the through hole of the pressure-sensitive plate, and the valve seat is formed from the intermediate chamber side. A valve body that comes into close contact with A is made to face, a valve A made of an elastic body is formed on the surface of the valve body that comes into close contact with the valve seat A, and the valve body is constantly urged so that the valve A comes into close contact with the valve seat A. The check valve is provided with a stopper that urges the valve body to limit the movement distance of the valve body to the inlet side and the outlet side, and restricts the movement of the valve body to the inlet side and the outlet side.

When the fluid pressure on the inlet side is higher than the fluid pressure on the outlet side (normal state), the inflowing fluid pushes the pressure sensitive disc and the valve body urged by the urging means to the valve seat A of the pressure sensitive disc to the outlet side. . When the valve body hits the stopper that restricts the movement of the valve body toward the outlet side, the valve body cannot move to the outlet side, only the pressure sensitive plate moves, and the valve seat A of the pressure sensitive plate leaves the valve A to open the valve. When the fluid pressure on the inlet side is lower than the fluid pressure on the outlet side (reverse pressure state), the valve body urged by the urging means to the pressure sensitive plate and the valve seat A of the pressure sensitive plate by the fluid pressure on the outlet side is in the closed state. Is pushed to. When the valve body hits the stopper that restricts the movement of the valve body toward the inlet side, the differential pressure applied to the pressure sensitive plate in addition to the urging force that urges the valve body presses the valve seat A against the valve A and increases the sealing force.

As described above, the valve seat is separated from the housing to form a pressure sensitive panel movable relative to the housing, whereby the pressure sensitive panel for sensing the differential pressure and the valve for opening and closing the fluid are separated from each other to reduce the flow resistance. It will be possible to achieve both a smaller size and higher sealing power.

According to the second aspect of the present invention, a water chamber is formed in the flow path connecting the inlet and the outlet of the housing, and the water chamber is partitioned into an intermediate chamber and a secondary chamber in a watertight manner in the axial direction. A pressure-sensitive board that is movable and has a through hole that communicates between the intermediate chamber and the secondary chamber is installed in the axial center part, and a valve seat A is formed around the intermediate chamber side of the through hole of the pressure-sensitive board. A valve seat B is integrally or integrally formed with the housing around the inlet of the intermediate chamber of the flow path connecting the chambers.
In the intermediate chamber between the valve seat B and the valve seat B, the valve body having the valve A formed of an elastic body on the surface in close contact with the valve seat A and the valve B formed of the elastic body on the surface in close contact with the valve seat B is assembled. Valve A, valve seat B to valve B
Are opposed to each other, and a stopper is provided to urge the valve body by the urging means so that the valve A is always in close contact with the valve seat A, and a stopper is provided to limit the moving distance of the valve body to the outlet side. It is a double check valve that regulates the movement of the.

When the inlet side fluid pressure is higher than the outlet side fluid pressure (normal state), the inflowing fluid pushes the pressure sensitive disc and the valve body biased by the biasing means to the outlet side of the valve seat of the pressure sensitive disc,
The valve B is separated from the valve seat B and opened. When the valve element further moves toward the outlet side and hits the stopper that restricts the movement of the valve element toward the outlet side, the valve element cannot move to the outlet side and only the pressure sensitive plate moves, and the valve seat A of the pressure sensitive plate leaves the valve A. Open the valve.

When the fluid pressure on the inlet side is lower than the fluid pressure on the outlet side (reverse pressure state), the valve body urged by the urging means to the valve seat of the pressure sensitive disk and the pressure sensitive disk by the fluid pressure on the outlet side is in the closed state and is the inlet. Is pushed to the side, the valve B of the valve element hits the valve seat B and closes, and in addition to the urging force that urges the valve element, the differential pressure applied to the pressure sensitive plate pushes the valve seat A against the valve A and the valve B Press on the seat B to increase the sealing force.

Therefore, the valve seat A and the valve A of one of the double check valves are
The open / close mechanism by means of the valve seat closes to the valve and opens and closes. On the other hand, the open / close mechanism by valve seat B and valve B operates as a check valve that opens and closes as the valve closely contacts the seat fixed to the housing. It is a double check valve that combines check valves with the same structure.

According to a third aspect of the present invention, there is provided a decompression type backflow preventer in which two sets of conventional check valves are installed as a first check valve and a second check valve in a passage connecting an inlet and an outlet of a housing. A primary chamber between the inlet and the first check valve upstream of the one check valve, an intermediate chamber between the first check valve and the second check valve, and a secondary chamber between the second check valve and the outlet. Instead of separating the flow path into and, the double check valve is installed and the opening / closing mechanism by the valve seat B and the valve B of the double check valve is replaced by the first check valve and the opening / closing mechanism by the valve seat A and the valve A. Since the second check valve is separated into the primary chamber, the intermediate chamber, and the secondary chamber, the same effect as that of the double check valve described above is obtained, and the decompression type backflow preventer is highly safe.

In a fourth aspect of the present invention, a valve body A is formed by forming a valve A made of an elastic body on the surface of the valve body that is in close contact with the valve seat A, and a valve B made of an elastic body is formed on the surface that is in close contact with the valve seat B. The valve body B is separated into the formed valve body B, and the valve body B is movably assembled to the valve body A in the set distance axial direction so that the valve body A and the valve body B are separated from each other between the valve body A and the valve body B. After the valve B contacts the valve seat B, the valve body A is pushed toward the inlet side by about 0.1 mm to 3 m after the valve B comes into contact with the stopper that limits the moving distance of the valve body A toward the inlet side.
It was installed at a position where it would move and stop.

To open the valve body B by pushing it away from the valve seat B, the product of the difference between the primary chamber pressure and the intermediate chamber pressure of the fluid flowing from the inlet side and the area of the valve B is the valve body A and the valve body. When the urging force applied during B is overcome and the counter pressure is applied, the valve seat B
Until the valve B contacts the valve body A and the valve body B move integrally,
When the valve B comes into contact with the valve seat B, the valve body A moves 0.1 mm to 3 mm against the biasing force applied between the valve bodies A and B to press the valve B against the valve seat B. From the valve seat B to the valve seat B, the force that presses the valve B against the valve seat B becomes the pressure difference between the primary chamber pressure and the intermediate chamber pressure, and the valve seat B and the valve seat B. The opening / closing mechanism by B is a check valve that is not related to the valve body A biased by the pressure sensitive plate and the pressure sensitive plate by the biasing means. Other operations are the same as the valve element of the double check valve described above.

In the invention according to claim 5, since the pressure sensitive plate is of the diaphragm type, there is no sliding resistance for the pressure sensitive plate to move in a watertight state, and a more accurate check valve, double check valve and It can be a decompression type backflow preventer.

[0019]

Embodiments Next, embodiments will be described in detail with reference to the drawings. The same reference numerals are used for the constituent elements having the same effect as those of the conventional means.

FIG. 1 is a vertical cross-sectional view of a check valve having a diaphragm type pressure-sensitive plate embodying the present invention. In FIG.
Is a housing, 1 is an inlet housing having an inlet 7 of the housing A, 2 is an outlet housing having an outlet 8 of the housing A, and 3 is a pressure sensitive plate in which a valve body 5, a valve seat metal fitting 6 and the like are attached to a diaphragm 4. It is a diaphragm ASSY, and is assembled by holding the diaphragm ASSY 3 in a watertight manner by the inlet housing 1 and the outlet housing 2 and connecting them with screws (not shown).

The inlet housing 1 is provided with an inlet 7, a collar 9 for holding the diaphragm 4 in a watertight manner on the other end surface of the inlet 7 and an intermediate chamber 11 in the inner cavity, and a flow path connecting the inlet 7 and the intermediate chamber 11. In the vicinity of the intermediate chamber of the valve body 5 with the same central axis as the collar 9,
An entrance stopper 13 is formed to limit the moving distance of the entrance to the entrance side.

The outlet housing 2 is provided with an outlet 8, a collar 10 for holding the diaphragm 4 in a watertight manner at the other end surface of the outlet 8 and a secondary chamber 12 in the inner cavity, and connects the outlet 8 and the secondary chamber 12 to each other. An outlet stopper 1 for limiting the moving distance of the valve body 5 to the outlet side by making the central axis the same as that of the collar 10 in the vicinity of the secondary chamber of the flow path.
4 is formed.

The diaphragm ASSY 3 is a valve seat having a hole at the center of a diaphragm 4 having a holding portion at the outer peripheral edge thereof, and a through hole for communicating the intermediate chamber 11 and the secondary chamber 12 at the center of the hole. The metal fitting 6 is watertightly attached by caulking or the like.
A valve seat A15 is formed around the through hole on the side of the intermediate chamber of the valve seat fitting 6, a boss 22 is formed at the center of the through hole, and the valve shaft 19 of the valve body 5 is fitted to the axial center of the boss 22. The through hole 16 to be inserted is formed, and the valve A 18 made of an elastic body is attached to the valve fitting 17 on the valve shaft 19.
The valve body 5 fixed by the above is inserted into the through hole 16 of the boss 22 from the valve seat A side by inserting the valve shaft 19 of the valve body 5 into the valve seat A1.
5, the spring A21 is urged between the end surface of the boss 22 and the tip of the valve shaft 19 by the push nut 20 so that the valve A18 is always in close contact with the valve seat A15.

Then, the diaphragm ASSY 3 is set in the inlet housing 1 with the valve body 5 as the inlet housing side, and the outlet housing 2 is mounted and assembled by screws (not shown).

Then, the fluid flowing from the inlet 7 enters the intermediate chamber 11 through the flow path, and due to the pressure difference between the intermediate chamber 11 and the secondary chamber 12, the valve body is brought into close contact with the valve seat A15 by the diaphragm 4 and the spring A21. Push 5 toward the exit side. Valve shaft 1 of valve body 5
When the tip of 9 hits the outlet stopper 14, the valve body 5 cannot move to the outlet side. Therefore, the valve seat A15 attached to the diaphragm 4 causes the spring A21 to bend and the valve A18.
And moves toward the outlet side to open the valve as shown in FIG. 2, and the fluid flows out to the outlet.

When a back pressure is generated in which the pressure on the outlet side is higher than the pressure on the inlet side, the differential pressure between the intermediate chamber 11 and the secondary chamber 12 causes
The diaphragm 4 moves to the inlet side, and the spring A21 causes the valve seat A15 to abut against the valve A18 to close the valve.
When the valve A18 moves to the inlet side with the valve closed, and the inlet side end of the valve body 5 hits the inlet stopper 13 and the valve body 5 stops as shown in FIG. 1, the valve seat A15 presses the valve A18. As for the force, the biasing force of the spring A21 and the force of the differential pressure applied to the diaphragm 4 are added to increase the sealing force.

FIG. 3 is a vertical cross-sectional view of a double check valve embodying the present invention. The inlet housing 1 is provided with an inlet 7, a collar 9 for holding the diaphragm 4 in a watertight manner at the other end surface of the inlet 7 and an intermediate chamber 11 in the inner cavity, and an intermediate chamber inlet of a flow path connecting the inlet 7 and the intermediate chamber 11. Around the circumference, the center axis is the same as the collar 9 and the valve seat B
23 is formed. The outlet housing 2 is no different from the check valve outlet housing 2 described above.

The diaphragm ASSY3 is provided with recesses on both sides of the valve fitting 17 of the valve body 5 for incorporating a valve made of an elastic body.
The check valve described above except that the valve A18 facing the valve seat A15 is mounted on one surface and the valve B24 facing the valve seat B23 is mounted on the other surface, and the valve body 5 is fixed from the valve A side by the valve shaft 19. No change from the diaphragm ASSY3.

The diaphragm ASSY is installed in the inlet housing 1.
Assembling the valve body 5 by setting the valve body 5 on the inlet housing side, mounting the outlet housing 2 and coupling them with screws (not shown) is the same as the above-described check valve embodiment.

The fluid flowing from the inlet 7 enters the primary chamber 25 between the inlet 7 and the valve seat B23 through the flow path, and the differential pressure between the primary chamber 25 and the intermediate chamber 11 causes the diaphragm 4 and the spring A21 to valve the valve. The valve body 5 biased by the seat A15 is pushed to push the valve B24 away from the valve seat B23 to open the valve and enter the intermediate chamber 11. The differential pressure between the intermediate chamber 11 and the secondary chamber 12 causes the diaphragm 4 to move to the diaphragm 4. The valve body 5 biased by the valve seat A15 by the spring A21 is pushed to the outlet side. When the tip of the valve shaft 19 of the valve body 5 hits the outlet stopper 14, the valve body 5 cannot move toward the outlet side, so the valve seat A15 attached to the diaphragm 4 deflects the spring A21 and leaves the valve A18 to leave the outlet side. The valve opens as shown in FIG. 4 and the fluid flows out to the outlet.

When a back pressure is generated, the diaphragm 4
Moves to the inlet side due to the pressure difference between the intermediate chamber 11 and the secondary chamber 12,
When the valve seat A15 contacts the valve A18 by the spring A21 to close the valve, and when the valve seat A15 and the valve A18 are closed to move to the inlet side, the valve B24 contacts the valve seat B23 and is shown in FIG. The valve is closed as described above to form a double valve closing mechanism. Further, when a differential pressure is applied to the diaphragm 4, the valve seat A15 is closed by the valve A18.
At the same time, the valve B24 is pressed against the valve seat B23 to increase the sealing force. Further, as shown in FIG. 11, a spring B26 is provided between the secondary chamber side of the diaphragm 4 and the outlet housing 2.
May be urged.

FIG. 9 is a vertical sectional view of a decompression type backflow preventer embodying the present invention, in which A is a housing and 1 is a housing A.
Of the above-described double-check valve embodiment having an inlet 7 of the above, an inlet housing having a second pressure chamber 33 formed on the side surface of the inlet housing 2, 2 an outlet housing having an outlet 8 of the housing A, 3 a diaphragm 4. Diaphragm ASSY, 34 to which the valve body 5, valve seat fitting 6 and the like are assembled is a diaphragm B.
Diaphragm ASSY with valve element C35 attached to 29
B and 36 are pressure chamber lids that fix the diaphragm ASSYB and form the first pressure chamber 37. The diaphragm ASSY3 is watertightly held by the inlet housing 1 and the outlet housing 2 and is joined by screws (not shown), The diaphragm AS is provided on the outer end surface of the second pressure chamber 33 on the side surface of the inlet housing 1.
The SYB 34 is watertightly held by the pressure chamber lid 36 and is joined by screws (not shown).

The inlet housing 1 is provided with an inlet 7, a collar 9 for holding the diaphragm 4 in a watertight manner at the other end surface of the inlet 7 and an intermediate chamber 11 in the inner cavity, and a passage connecting the inlet 7 and the intermediate chamber 11 with each other. The central axis is the same as that of the collar 9 around the inlet of the intermediate chamber, and the valve seat B
A collar 38 for holding the diaphragm B29 in a watertight manner on the side surface of the inlet housing 1 in which 23 is formed, and a second pressure chamber 33 is formed in the inner cavity, and a communication hole for communicating the second pressure chamber 33 and the intermediate chamber 11 with each other. B39 is formed and the inlet 7 and valve seat B23 are formed.
A communication hole A40 for communicating the primary chamber 25 between the first pressure chamber 37 formed in the pressure chamber lid 36 with the first pressure chamber 37 is opened in the widened part of the collar 38, and the second pressure chamber is formed. A communication hole 30 communicating with the external discharge port 41 is opened at the bottom of the axial center of 33, and a valve seat C31 is formed around the opening on the second pressure chamber side.

The pressure chamber cover 36 has a flange 42 for holding the diaphragm B29 in a watertight manner on the outer end surface of the recess corresponding to the first pressure chamber 37, and a part of the flange 42 corresponding to the opening of the communication hole A40 described above. Is widened to form a hole 43 matching the opening so that the primary chamber 25 and the first pressure chamber 37 communicate with each other.

The diaphragm ASSYB34 is provided with a valve C32 facing the valve seat C31 at the central portion of the diaphragm B29 having a sandwiching portion formed with a through hole 44 corresponding to the hole 43 at the outer peripheral edge. There is no problem even if the valve C32 is formed separately and is integrally attached to the diaphragm B29.

Outlet housing 2 and diaphragm ASS
Y3 is the same as the double check valve described above.

The diaphragm ASSY is installed in the inlet housing 1.
3 is set with the valve body 5 on the inlet housing side, the outlet housing 2 is mounted and assembled by screws (not shown), and the diaphragm ASSYB34 is attached to the outer end surface of the second pressure chamber 33 on the side surface of the inlet housing 1. The valve C32 is on the second pressure chamber side, and the opening of the communication hole A40 and the through hole 4 at the outer peripheral edge portion
4 together and set the pressure chamber lid 36 to the above-mentioned through hole 44.
By assembling the hole 43 of the pressure chamber lid 36 with, and forming a communication hole A40 for communicating the primary chamber 25 and the first pressure chamber 37 with each other, and mounting with a screw (not shown) to assemble.

Since the operation of the double check valve portion is the same as that of the double check valve described above, the description thereof will be omitted, and the operation of the other portions will be described. The fluid flowing from the inlet 7 enters the primary chamber 25 through the flow path, pushes the valve B24 away from the valve seat B23 and opens the valve to enter the intermediate chamber 11, and the diaphragm 4 and the valve seat A
When the valve element 5 urged by the spring A21 to 15 is pushed toward the outlet side and the tip of the valve shaft 19 of the valve element 5 abuts against the outlet stopper 14, the valve seat A15 attached to the diaphragm 4 bends the spring A21. There is no difference from the double check valve described above in that the valve A18 is moved away from the valve A18 to the outlet side, and the valve is opened and the fluid flows to the outlet.
Since the pressure of 5 passes through the communication hole A40 and pressurizes the first pressure chamber 37, and the pressure of the intermediate chamber 11 passes through the communication hole B39 and pressurizes the second pressure chamber 33, the diaphragm B29 moves to the primary chamber 25 (first pressure chamber). It moves in the axial direction due to the pressure difference between the pressure in the chamber 37) and the pressure in the intermediate chamber 11 (second pressure chamber 33).

When the pressure in the primary chamber 25 is higher than the pressure in the intermediate chamber 11, the diaphragm B29 moves to the second pressure chamber side and the valve C integrally formed on the second pressure chamber side of the diaphragm B29.
32 is pressed against a valve seat C31 formed in the opening of the communication hole 30 communicating with the external discharge port 41 to close the valve, and the second pressure chamber 33 (intermediate chamber 11) and the external discharge port 41 are shut off (FIG. 10). When the pressure in the primary chamber 25 is lower than the pressure in the intermediate chamber 11 (reverse pressure), the diaphragm B29 moves to the first pressure chamber side and the valve C32 is separated from the valve seat C31 and opened to open the second pressure chamber 33 (intermediate chamber 1).
1) is communicated with the external outlet 41 and opened (FIG. 9).

In a normal flow, the pressure in the primary chamber 25 and the pressure in the intermediate chamber 11 are high in the primary chamber 25 due to the pressure loss required to open the valve B24. In the embodiment shown in FIG. 11, the spring B26 is urged between the secondary chamber side of the diaphragm 4 and the outlet housing 2 to increase the pressure loss, thereby increasing the primary chamber 25.
In the example of the double check valve in which the pressure difference between the pressure of 1 and the pressure of the intermediate chamber 11 is increased, the same method may be used for the decompression check valve. In the embodiment, the intermediate chamber 11 and the second pressure chamber 33
Through the communication hole B39, and the valve C32 was opened and closed by the pressure difference between the pressure in the primary chamber 25 and the pressure in the intermediate chamber 11, but the secondary chamber 12 and the second pressure chamber 33 were communicated by the communication hole. The valve C32 may be opened and closed by the pressure difference between the pressure in the chamber 25 and the pressure in the secondary chamber 12. Diaphragm B2
It is also possible to assist the closing or opening of the valve C32 by urging a spring (not shown) between the first pressure chamber side or the second pressure chamber side of 9 and the housing.

FIG. 7 is an enlarged vertical sectional view of a modification of the valve body 5. In the embodiment of the double check valve described above, the valve fitting 17 has a valve A18.
Replace the valve B24 with the valve body 5 fixed by the valve shaft 19,
A valve A made of an elastic body on the surface of the valve body 5 that is in close contact with the valve seat A15.
Separated into a valve body A45 having 18 formed therein and a valve body B46 having a valve B24 made of an elastic body on the surface closely contacting the valve seat B23, the valve body B46 is movable in the axial direction set by the valve body B46 with respect to the valve body A45. , And a spring C47 is urged between the valve body A45 and the valve body B46, so that the valve body B46 is pressed against the valve body A45.
7 has a degree of freedom in the axial direction, and in the example of FIG. 7, the valve body B46 is slidably and watertightly inserted into the shaft 48 extending below the valve body A45, and the push nut 4 is attached to the end surface of the shaft 48.
9 is fitted and the moving distance of the valve body B46 is regulated, and the valve body A4
A spring C47 is biased between the valve 5 and the valve element B46. As a stopper for limiting the moving distance of the valve body A45 to the inlet side, the valve B24 comes into contact with the valve seat B23 and then the support plate 50 abuts the housing after the valve body A45 moves 0.1 mm to 3 mm. Has been extended.

The fluid flowing from the inlet 7 enters the primary chamber 25 through the flow path, and the valve body B is driven by the pressure difference between the primary chamber 25 and the intermediate chamber 11.
46 is pushed against the spring C47, the valve B24 is released from the valve seat B23, the valve is opened, and the intermediate chamber 11 is entered.
Diaphragm 4 and valve seat A1 due to the differential pressure between 1 and secondary chamber 12
The valve element A45, which is urged by the spring A21, is pushed to the outlet side. The valve body B46 is the push nut 4 on the end face of the shaft 48.
When hitting 9, the valve body A45 and the valve body B46 become integral and move together with the diaphragm 4 toward the outlet side. Valve shaft 1 of valve body A45
9 When the tip hits the outlet stopper 14, the valve body A4
5 cannot be moved toward the outlet side, the valve seat A15 attached to the diaphragm 4 causes the spring A21 to bend and the valve A
The fluid flows out to the outlet by leaving 18 and moving toward the outlet to open the valve.

When a counter pressure is generated in which the pressure on the outlet side is higher than the pressure on the inlet side, the diaphragm 4 moves toward the inlet side due to the pressure difference between the intermediate chamber 11 and the secondary chamber 12, and the spring A21 causes the valve seat A1 to move.
5 contacts the valve A18 and closes it, and further moves to the inlet side with the valve seat A15 and the valve A18 closed. When the valve body B46 that moves integrally with the valve body A45 contacts the valve seat B23, the valve body A45 bends the spring C47 and moves by 0.1 mm to 3 mm, and the support plate 50 extended to the valve body A45 moves to the housing. It stops by hitting it. The force of pressing the valve B24 against the valve seat B23 is the urging force of the spring C47 and the primary chamber 25 applied to the valve B24.
And the differential pressure in the intermediate chamber 11 is reached.

[0044]

As described above, in the check valve according to the present invention, the valve seat A is separated from the housing and is formed on the pressure sensitive plate movable with respect to the housing, and the valve A is opposed to the valve seat A. The valve body is urged to restrict the movement of the valve body toward the outlet side, and the valve body opens when the valve body hits the stopper. Therefore, the pressure sensitive panel that senses the differential pressure and the fluid are opened and closed. Since the valve is a separate body, the flow resistance and the sealing force of the valve can be determined by the balance between the diameter of the pressure sensitive plate and the force that urges the valve. Further, a fixed valve seat B is provided at the inlet of the intermediate chamber, a valve B facing the valve seat B is attached to the valve body, and the valve body (valve B) is energized by the pressure sensitive board and moves integrally with the pressure sensitive board. By forming an opening / closing mechanism that opens and closes, a double check valve is created.
It is a combination of an opening / closing mechanism that moves the valve seat and an opening / closing mechanism that fixes the valve seat, and a combination of check valves of different structures provides a highly reliable double check valve. Further, by using the pressure reducing type backflow preventer using the double type check valve described above, the pressure reducing type backflow preventer is as reliable as the double type check valve.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a check valve embodying the present invention.

FIG. 2 is a vertical sectional view of the same check valve when opened.

FIG. 3 is a vertical cross-sectional view of a double check valve embodying the present invention.

FIG. 4 is a vertical cross-sectional view of the double check valve when the same is opened.

FIG. 5 is a vertical sectional view of a conventional check valve.

FIG. 6 is a vertical sectional view of a conventional double check valve.

FIG. 7 is an enlarged vertical sectional view showing another embodiment of the valve body.

FIG. 8 is an enlarged vertical sectional view of the same valve when the valve is opened.

FIG. 9 is a vertical cross-sectional view of a decompression type backflow preventer implementing the present invention.

FIG. 10 is a vertical sectional view of the decompression type backflow preventer when the valve is opened.

FIG. 11 is a vertical cross-sectional view showing another embodiment of the double check valve embodying the present invention.

FIG. 12 is a longitudinal sectional view of a conventional decompression type backflow preventer.

[Explanation of symbols]

A --- Housing 1 --- Inlet housing 2 ---- Outlet housing 3 --- Diaphragm ASSY 4 --- Diaphragm 5--Valve element 7 --- Inlet 8 --- Outlet 11 --- Intermediate chamber 12 --- Secondary chamber 13 --- Inlet stopper 14 --- Outlet stopper 15 --- Valve seat A 18 --- Valve A 19 --- Valve shaft 21 --- Spring A 23 --- Valve seat B 24--Valve B 25 --- Primary chamber 27-First check valve 28-Second check valve 29-Diaphragm B 31-Valve seat C 32--Valve C 33-Second pressure chamber 34-Diaphragm ASSYB 35-Valve Body C 36-Pressure chamber lid 37-First pressure chamber 39-Communication hole B 40-Communication hole A 41-External discharge port 45-Valve A 46-Valve B 47-Spring C 48 --- shaft 49 --- push nut 50 ---- support plate

Claims (5)

[Claims] 1. A water chamber is formed in a flow path connecting an inlet and an outlet of a housing, and the water chamber is partitioned into an intermediate chamber and a secondary chamber in a watertight manner so as to be movable in an axial direction. Is equipped with a pressure sensitive plate having a through hole that communicates the intermediate chamber and the secondary chamber, and a valve seat A is formed around the intermediate chamber side of the through hole of the pressure sensitive plate.
The valve body made of an elastic body is formed on the surface of the valve body that comes into close contact with the valve seat A, and the valve body is biased so that the valve A always comes into close contact with the valve seat A. A non-return valve that is provided with a stopper that restricts the movement distance of the valve body to the inlet side and the outlet side by restricting the movement of the valve body to the inlet side and the outlet side. 2. A water chamber is formed in a flow path connecting an inlet and an outlet of a housing, and the water chamber is watertightly divided into an intermediate chamber and a secondary chamber, and is movable in the axial direction, so that an axial center portion is formed. Is equipped with a pressure sensitive plate having a through hole communicating the intermediate chamber and the secondary chamber, and a valve seat A is formed around the intermediate chamber side of the through hole of the pressure sensitive plate to connect the inlet and the intermediate chamber. A valve seat B is integrally or integrally formed with the housing around the inlet of the intermediate chamber of the valve, and a valve formed of an elastic body on the surface of the intermediate chamber between the valve seat A and the valve seat B is in close contact with the valve seat A. Assembling a valve body in which a valve B made of an elastic body is formed on the surface that is in close contact with A and the valve seat B, the valve A is opposed to the valve seat A, and the valve B is opposed to the valve seat B.
The valve body is constantly urged by the urging means so that the valve A is in close contact with the valve seat A, and a stopper for limiting the moving distance of the valve body to the outlet side is provided to restrict the movement of the valve body to the outlet side. Double check valve. 3. A water chamber is formed in a flow path connecting an inlet and an outlet of a housing, and the water chamber is partitioned into an intermediate chamber and a secondary chamber in a watertight manner so as to be movable in the axial direction, and an axial center portion. Is equipped with a pressure sensitive plate having a through hole communicating the intermediate chamber and the secondary chamber, and a valve seat A is formed around the intermediate chamber side of the through hole of the pressure sensitive plate to connect the inlet and the intermediate chamber. A valve seat B is integrally or integrally formed with the housing around the inlet of the intermediate chamber of the valve, and a valve formed of an elastic body on the surface of the intermediate chamber between the valve seat A and the valve seat B is in close contact with the valve seat A. Assembling a valve body in which a valve B made of an elastic body is formed on the surface that is in close contact with A and the valve seat B, the valve A is opposed to the valve seat A, and the valve B is opposed to the valve seat B.
The valve body is constantly urged by the urging means so that the valve A is in close contact with the valve seat A, and a stopper for limiting the moving distance of the valve body to the outlet side is provided to restrict the movement of the valve body to the outlet side. The double check valve has a valve seat B and an opening / closing mechanism formed by the valve B as a first check valve and a valve seat A.
And a valve A for opening and closing mechanism as a second check valve 4. A valve body A in which a valve A made of an elastic body is formed on the surface of the valve body that is in close contact with the valve seat A, and a valve body B in which a valve B of an elastic body is formed in the surface that is in close contact with the valve seat B. Separately, the valve body B is movably assembled to the valve body A in the set axial direction, and a biasing means is provided between the valve bodies A and B so as to separate the valve bodies A and B from each other. A stopper that urges the valve body A to limit the moving distance of the valve body A toward the inlet side is installed at a position where the valve body A moves about 0.1 mm to 3 mm toward the inlet side after the valve B contacts the valve seat B and stops. A double check valve according to claim 2 and a pressure reducing backflow preventer according to claim 3. 5. The check valve according to claim 1, wherein the pressure sensitive panel is a diaphragm type, the double check valve according to claim 2, and the pressure reducing backflow preventer according to claim 3.