JP4319008B2 - Backflow prevention device - Google Patents

Description

The present invention relates to a backflow prevention equipment that middle provided tub sewage pipe for guiding hot water from the hot water supply device in a bath is prevented from flowing back into the water supply.

  In a conventional hot water supply system, for example, as shown in FIG. 6, a water supply water supply pipe 1 is connected to the upstream side of a heat exchanger 3 and a water bypass valve 4 via a flow rate sensor 2. And after the downstream side of the water bypass valve 4 joins, it is connected to the water proportional valve 5. The downstream side of the water proportional valve 5 is connected to a hot water supply pipe 6 for discharging hot water to, for example, a kitchen faucet.

  Further, the downstream side of the water proportional valve 5 is also connected to a hot water pipe 6 and a branched pipe 7, and the bath is connected through a flow sensor 8, an electromagnetic valve 9, and two check valves 110, 120 arranged in series. An air release valve 130 is disposed in the pipe 15 connected to the bathtub 14 and connected between the check valve 110 and the check valve 120.

  Among the above components, the check valves 110 and 120 and the air release valve 130 constitute a backflow prevention device that prevents backflow from the bathtub 14 to the water supply. The bathtub 14 illustrated here is installed at a position higher than the introduction position of the water supply pipe 1, for example, the second floor or the third floor if it is a detached house, and it is installed on the upper floors of the second floor or more if it is an apartment house. ing.

FIG. 7 is a cross-sectional view illustrating a configuration example of such a backflow prevention device of the hot water supply system. In the figure, the same components as those described in FIG. 6 are denoted by the same reference numerals.
As shown in FIG. 7, check valves 110 and 120 are arranged in series from the upstream side in the pipe 171 on the downstream side of the electromagnetic valve 9. That is, the pipe 171 has a stepped cylindrical shape that constitutes a part of the pipe 7, and the check valves 110 and 120 are inserted and fixed to the downstream step portions via the sealing O-rings 151 and 152, respectively. ing. Between the check valve 110 and the check valve 120, a spacer 160 having a plurality of openings 161 formed on the peripheral surface of a cylindrical main body is interposed. The opening 161 of the spacer 160 communicates with the atmosphere release valve 130 through an opening 172 provided on the pipe wall of the pipe 171. On the downstream side of the check valve 120, a pipe 173 constituting the pipe 7 is connected to the pipe 171 through an O-ring 153.

  The atmosphere release valve 130 has a body 135 that integrally includes a connection portion 133 connected between the check valve 110 and the check valve 120 of the pipe 171 and an overflow port 134 that is open to the atmosphere. Yes. A piston 136 having a double structure is arranged coaxially with the opening center of the connection portion 133 so as to be able to advance and retract in the axial direction, and an annular valve body 137 fitted to the piston 136 by the advance and retreat movement is connected to the piston 136. The passage between the space on the portion 133 side and the overflow port 134 is opened and closed. A diaphragm 138 is fixed on the opposite side of the piston 136 from the connection portion 133 side, and the outer peripheral portion of the diaphragm 138 is clamped and fixed by the bodies 141 and 142. The body 142 is provided with a connection portion (not shown) connected to the water supply pipe 1 via the pressure detection pipe 16 (see FIG. 6), and the space formed by the diaphragm 138 and the body 142 is the original pressure of the water supply pipe 1. Constitutes a room to receive.

  Returning to FIG. 6, in such a hot water supply system, the clean water supplied from the water supply pipe 1 passes through the flow rate sensor 2, is partially heated by the heat exchanger 3 to become hot water, and part is water bypass. It is mixed with hot water coming out of the heat exchanger 3 through the valve 4. At this time, by controlling the flow rate of bypassing the heat exchanger 3 by the water bypass valve 4, the mixing ratio of the hot water and the hot water temperature is controlled. The hot water controlled to a desired temperature is further supplied with hot water from the hot water supply pipe 6 with the hot water flow rate controlled by the water proportional valve 5.

  When filling the bathtub 14 with hot water, the solenoid valve 9 is opened so that the hot water that has flowed out of the water proportional valve 5 flows into the bath tub 14 via the flow sensor 8, the solenoid valve 9, and the check valves 110, 120. Supplied.

  At this time, the air release valve 130 is introduced with the original pressure (primary pressure) of the water supply via the pressure detection pipe 16. Since this primary pressure is larger than the water flow pressure (secondary pressure) in the pipe passing from the solenoid valve 9 through the check valves 110 and 120, the piston 136 is biased in the direction in which the valve body 137 is seated. The passage to the overflow port 134 is in a closed state.

  When a negative pressure is generated in the water supply pipe 1 due to a pump that pumps up the water due to a power failure or a water outage, etc., the air release valve 130 detects a decrease in the primary pressure. 138 urges the piston 136 in the valve opening direction to connect the pipe from the solenoid valve 9 to the check valve 110 with the overflow port 134 and release the water in the pipe to the atmosphere.

  If the check valve 120 has a poor watertightness due to foreign matter biting or the like, the sewage in the bathtub 14 at a high place can reach the air release valve 130 via the check valve 120 due to its head pressure. Although it flows backward, the sewage is discharged to the atmosphere by the atmosphere release valve 130, so that the sewage in the bathtub does not flow back to the hot water supply pipe 6.

In addition to such a hot water supply system, in the structure of a check valve installed in a pipe, a check valve is provided to prevent the backflowed fluid from leaking due to biting or catching of the valve portion. A configuration in which two stages are provided in series is known (for example, Patent Document 1).
JP 2000-110959 A

  Incidentally, in the check valve structure shown in FIG. 7, the check valves 110 and 120 are individually formed individually and are inserted into the stepped portion of the pipe 171 and fixed. That is, both the check valves are composed of a cylindrical casing 111 fixed to the inner peripheral surface of the pipe 171 and a valve body 112 pivotally supported by the casing 111. And the valve part 113 provided in the one end side of the valve body 112 is comprised so that a seat on the valve seat 114 provided in the front end side of the casing 111 is comprised, and the shaft part 115 of the valve body 112 is the other side of the casing 111. The bearing member 116 provided at the end portion is slidably supported.

  However, in such a configuration, the check valves are individually manufactured, and the O-rings 151 and 152 for fixing the check valves as described above are also required. In addition, since each check valve is formed as a single unit in this way, the above-described spacer 160 is separately prepared in order to form a flow path connected to the pipe 15 to the atmosphere release valve 130 between both check valves. Must.

This invention is made | formed in view of such a point, and it aims at implement | achieving the non-return valve structure comprised by a two-stage nonreturn valve by the simple structure which reduced the number of parts.

In the present invention, in order to solve the above-described problem, an electromagnetic valve installed in a pipe connected from a hot water supply pipe to a bathtub and allowing or preventing the flow of water in the pipe, and disposed on the bathtub side of the electromagnetic valve of the pipe A check valve structure that allows a flow of water from the solenoid valve to the bathtub, but prevents a reverse flow of water from the bathtub to the solenoid valve, and a pipe of the pipe having the check valve structure An air release valve connected to an opening formed in the wall and opened and closed to release water in the check valve structure to the atmosphere in response to a pressure drop on the water supply side. The check valve structure is configured to be able to be seated on a first valve seat formed of a step portion formed integrally with the pipe, and in the reverse direction of the fluid by being seated on the first valve seat in the pipe. A first valve body for blocking the flow of the first valve and the first valve in the pipe And a cylindrical main body fixed to the inner peripheral surface of the pipe, and the first valve body and the second valve body are respectively shafts. A casing that is integrally formed with a second valve seat that is slidably supported in a direction and that prevents the fluid from flowing in the reverse direction by seating the second valve body inside the body. The first valve body and the second valve body have a locking projection protruding at a predetermined position of a shaft portion slidably supported by the casing, while the locking projection is The first supporting portion is configured to be engaged with a locking protrusion projecting inwardly at a tip end portion of the shaft supporting portion of the casing that supports the shaft portion, and to prevent the casing from falling off. The corresponding first and second valve seats are located at the distal ends of the valve body and the second valve body. A flange portion having an outer shape larger than the peripheral edge of the opening, and a plate-like rubber packing that is externally fixed to the first and second valve seat sides of the flange portion and has an outer shape larger than the peripheral edge of the opening are provided. The rubber packing has a stepped portion that forms a predetermined gap with the flange portion by reducing the thickness of the outer peripheral portion including the vicinity of the contact position with the first and second valve seats. When the first and second valve bodies are seated, the stepped portion is bent toward the flange portion and is in close contact with the first and second valve seats on the side opposite to the flange portion. The opening of the pipe to which the atmosphere release valve is connected is surrounded by the first valve seat of the pipe and the end surface of the casing on the side supporting the first valve body. It is configured to communicate with the space A backflow prevention device is provided.

  Here, the “step portion formed integrally with the pipe” may be formed integrally when the pipe is formed, or may be formed by fixing a ring-shaped member inside the pipe, for example. However, it does not consist of the casing of the valve body or a part thereof. Further, the “pipe” may be a part of a long pipe of the entire system through which a fluid flows, or may be a dedicated pipe partially connected to the long pipe. Further, the “casing” may be one in which a shaft supporting portion that supports the first valve body and the second valve body is formed integrally with the main body, or another member as a bearing member is joined to the main body. You may have done.

Such a check valve structure of the backflow prevention device is configured as a check valve unit in which the first valve body and the second valve body are supported by one casing, and the first valve body casing and The valve seat on which the first valve body is seated is constituted by a pipe portion. For this reason, the casing for exclusive use of the 1st valve body like the case where the 1st valve body is constituted as an individual check valve can be omitted. As a result, inclusions (for example, an O-ring for sealing) when the casing is fixed to the pipe can be reduced.

In particular, piping is provided in the middle from the hot water supply pipe to the tub, the backflow prevention device for preventing a reverse flow of sewage into the water supply from the bath, to a predetermined position of the pipe wall of the pipe, depending on the pressure drop of the water supply pipe An opening connected to the atmosphere opening valve that opens and closes to release the water in the atmosphere is formed, and the space surrounded by the stepped portion of the pipe and the end face of the casing is arranged to communicate with the opening. If comprised in this way, it will become unnecessary to provide the spacer as described in the said prior art, and the opening part formed in piping can be utilized as it is. In addition, the backflow prevention device can be made compact because the spacer can be omitted.

According to the onset bright, it is possible to omit the spacer is installed between the first valve body dedicated casing and two-stage check valve, as a result, the inclusions in fixing the casing to the pipe Since it can be reduced, a backflow prevention device with a simple configuration with a reduced number of parts can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, the check valve structure of the present invention is applied to a backflow prevention device of a hot water supply system. FIG. 1 is a cross-sectional view showing the configuration of the backflow prevention device, and FIGS. It is an expanded sectional view showing composition of the check valve structure. The configuration of the entire hot water supply system is the same as that shown in FIG. 7 except for the configuration of the check valve unit 10 and the atmosphere release valve 20 to be described later. The description is omitted with reference to FIG.

  As shown in FIG. 1, the backflow prevention device according to the present embodiment is composed of a check valve unit 10 and an atmosphere release valve 20, and further, a flow sensor 8 and an electromagnetic wave on the upstream side (that is, the hot water supply pipe 6 side). The valve 9 is integrally provided to constitute a hot water supply adjusting device. The flow rate sensor 8 includes a plurality of blades 85 that increase in the number of rotations according to the flow rate of water flowing inside, and the electromagnetic valve 9 is a so-called pilot electromagnetic valve. Since a well-known thing is applied, detailed description thereof is omitted.

  As shown in FIG. 2, the check valve structure of the present embodiment is interpolated in a pipe expanding portion provided on the downstream side of the stepped cylindrical pipe 71 (which constitutes the pipe 7) and the pipe expanding portion. And a check valve unit 10.

  As shown in FIG. 3, the check valve unit 10 supports the first valve body 30 and the second valve body 40 that are coaxially arranged, and these valve bodies are slidable in the axial direction. It is comprised from the casing 50. FIG.

  The first valve body 30 is formed with a disk-like flange portion 31 extending in the radial direction at one end portion of a long-axis cylindrical main body made of a resin material, and further having a small-diameter portion 32 at the tip end side in the axial direction. A locking portion 33 protruding a predetermined amount in the radial direction is formed. A disc-like rubber packing 60 is attached so as to be sandwiched between the flange portion 31 and the locking portion 33 while being extrapolated to the small diameter portion 32. The rubber packing 60 has a slightly larger outer shape than the flange portion 31, and the stepped portion 61 is formed by reducing the thickness of the outer peripheral portion thereof. In addition, a circular hole 62 having substantially the same diameter as the small diameter portion 32 is formed in the center of the rubber packing 60, and the periphery of the circular hole 62 extends along the smooth tip periphery of the locking portion 33 when mounted on the main body. When it reaches the small-diameter portion 32, it is elastically restored and fitted therewith. As described above, the rubber packing 60 is locked in such a manner that the rubber packing 60 is sandwiched between the flange portion 31 and the locking portion 33, thereby preventing the rubber packing 60 from falling off the main body. A predetermined gap is formed between the rubber packing 60 and the flange portion 31 by the stepped portion 61, and the valve portion of the first valve body 30 is configured by the rubber packing 60 and the flange portion 31. In addition, the opposite side of the main body flange 31 to the locking portion 33 is a shaft portion 34 that slides with respect to the casing 50. A disc-shaped locking portion 35 for locking the end portion of the coil spring 77 is projected. Further, a part of the outer peripheral surface of the shaft portion 34 is cut out in the axial direction, and a locking projection 36 protruding in a predetermined amount in the outer direction is provided in the vicinity of the axial center of the cut-out surface. .

Since the second valve body 40 has the same structure as that of the first valve body 30 in the present embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.
On the other hand, the casing 50 has a bottomed stepped cylindrical main body 51 integrally formed of a resin material, and a cylindrical boss portion 53 is formed from an opening edge of an insertion hole 52 provided in the center of the bottom portion. An axial support portion that extends in the axial direction and supports the shaft portion 34 of the first valve body 30 is configured by the boss portion 53. A locking protrusion 53 a that protrudes inward is formed at the tip opening of the boss 53. The first valve body 30 is prevented from dropping from the casing 50 by the engagement between the locking projection 53a and the locking projection 36. Both the locking projections 36 and the locking projections 53a have flexibility, and the first valve body 30 is elastically deformed by applying a predetermined external force. In other words, the first valve body 30 is configured to be relatively detachable from the casing 50 by artificially applying a force from the outside.

  In addition, a plurality of through holes 54 for flowing water downstream are formed at predetermined intervals around the boss portion 53 at the bottom. A coil spring that urges the first valve body 30 in the valve closing direction between the bottom portion of the casing 50 and the flange portion 31 of the first valve body 30 so as to be extrapolated to the boss portion 53 and the locking portion 35. 77 is interposed.

Furthermore, the valve seat 55 for seating the valve part of the 2nd valve body 40 by the step part formed in the expansion part of the main body 51 is formed.
A bearing member 80 that pivotally supports the second valve body 40 is fitted and fixed in the opening 56 on the side opposite to the bottom of the main body 51. The bearing member 80 has a bottomed cylindrical main body having an outer diameter substantially the same as the inner diameter of the opening 56, and the boss portion 53 extends from the opening edge of the insertion hole 81 provided in the center of the bottom. A boss portion 82 having the same shape as that of the second valve body 40 is formed by the boss portion 82 extending in the axial direction, and a shaft support portion that supports the shaft portion 34 of the second valve body 40 is configured. A locking protrusion 82 a protruding inward is formed at the tip opening of the boss 82. The second valve body 40 is prevented from dropping from the casing 50 by the engagement between the locking projection 82a and the locking projection 36. Both the locking protrusion 36 and the locking protrusion 82a have flexibility, and the second valve body 40 is elastically deformed by applying a predetermined external force. That is, the second valve body 40 is configured to be relatively detachable from the casing 50 by artificially applying an external force.

  Further, a flange portion 83 extending outward is provided around the bottom portion, and the flange portion 83 is locked to the end surface of the opening 56 of the main body. Furthermore, a plurality of through holes 84 for flowing water downstream are formed around the boss portion 82 at the bottom at predetermined intervals. Between this bottom part and the flange part 31 of the 2nd valve body 40, the coil spring 78 which urges | biases the 2nd valve body 40 in the valve closing direction in the aspect extrapolated by the boss | hub part 82 and the latching | locking part 35 is provided. It is intervened.

  Returning to FIG. 2, a valve seat 73 for seating the first valve body 30 along the periphery of the opening is formed in the step opening 72 formed by the expanded portion of the stepped cylindrical pipe 71. An opening 74 connected to the atmosphere release valve 20 is formed at a predetermined position on the side wall of the pipe 71. Further, the stepped portion 75 is formed by slightly expanding the tube slightly downstream from the opening 74.

  And the non-return valve unit 10 comprised as mentioned above is inserted in the piping 71 in the state which attached the O ring 91 to the groove part provided in the outer peripheral surface. The check valve unit 10 is fixed in the pipe 71 in such a manner that a flange portion 57 provided around the outer peripheral surface on the front end side of the casing 50 is locked to the stepped portion 75. At this time, a space surrounded by the stepped portion where the valve seat 73 is located in the pipe 71 and the end surface (bottom portion) of the casing 50 communicates with the opening 74.

Returning to FIG. 1, on the downstream side of the check valve unit 10, a pipe 76 constituting the pipe 7 is connected to the pipe 71 via an O-ring 92.
The air release valve 20 has a body 23 integrally provided with a connection portion 21 connected to the opening 74 of the pipe 71 and an overflow port 22 opened to the atmosphere. A piston 24 having a double structure is arranged coaxially with the center of the opening of the connection portion 21 so as to advance and retreat in the axial direction, and an annular valve body 25 fitted to the piston 24 by the advance and retreat movement is connected to the piston 24. The passage between the space on the part 21 side and the overflow port 22 is configured to open and close.

  On the opposite side of the piston 24 from the connecting portion 21 side, the center portion of the diaphragm 26 is fixed by a retainer 94 and a screw 95. The diaphragm 26 has a deep folded portion and has a cylindrical shape capable of operating a long stroke while keeping an effective pressure receiving area constant. The outer peripheral portion of the diaphragm 26 is clamped and fixed by the bodies 27 and 28. The body 28 is provided with a connecting portion 29 that is connected to the water supply pipe 1 via the pressure detection pipe 16 (see FIG. 8), and the space formed by the diaphragm 26 and the body 28 reduces the original pressure of the water supply pipe 1. It constitutes a room to receive. The piston 24 is urged by a spring 99 in a direction to open the passage between the connection portion 21 and the overflow port 22, and the stroke in the opening direction is regulated by contact with the intermediate body 27. ing.

Next, the operation of the backflow prevention device configured as described above will be described with reference to FIGS.
First, FIG. 1 shows a state in which the electromagnetic valve 9 is turned off and water is not supplied from the water supply pipe 1 to the bath tub 14.

  At this time, since the valve body of the electromagnetic valve 9 is in the closed state, water from the upstream side does not flow into the pipe 71. For this reason, the first valve body 30 and the second valve body 40 are seated on the valve seats 73 and 55 by the urging forces of the coil springs 77 and 78, respectively, and are closed.

  On the other hand, in the atmosphere release valve 20, since the original pressure (primary pressure) of the water supply is introduced to the connection portion 29 via the pressure detection pipe 16, the piston 24 is pressed and the valve body 25 connects the connection portion 21 of the piston 24. The passage between the side space and the overflow port 22 is closed.

Next, FIG. 4 shows a state in which the electromagnetic valve 9 is turned on and water is supplied from the water supply pipe 1 to the bath tub 14.
At this time, since the valve body of the electromagnetic valve 9 is in an open state, water from the upstream side flows into the pipe 71, and the first valve is caused by the water flow pressure (secondary pressure) in the pipe 71 at that time. The body 30 and the second valve body 40 are opened.

  On the other hand, in the atmosphere release valve 20, the source pressure (primary pressure) of the water supply is introduced to the connection portion 29 via the pressure detection pipe 16, and this primary pressure is higher than the secondary pressure, so The passage is closed.

For this reason, the hot water that has exited the water proportional valve 5 is supplied to the bath tub 14 via the first valve body 30 and the second valve body 40.
Next, FIG. 5 shows a state in which a negative pressure is generated in the water supply pipe 1 due to a pump that pumps up the water due to a power failure or a water stoppage.

  At this time, in the atmosphere release valve 20, the diaphragm 26 that senses a decrease in the primary pressure urges the piston 24 in the valve opening direction, and connects the opening 74 of the pipe 71 to the overflow port 22. Release water into the atmosphere.

  If the second valve body 40 has a poor watertightness due to the biting of foreign matter, etc., the sewage in the bathtub 14 at a high place is caused to flow through the second valve body 40 by the water head pressure. Although it flows back to the open valve 20, the sewage is discharged to the atmosphere by the air release valve 20, so that the sewage in the bathtub 14 does not flow back to the hot water supply pipe 6.

  As described above, the check valve structure according to the present embodiment is configured as the check valve unit 10 in which the first valve body 30 and the second valve body 40 are supported by one casing 50. The pipe 71 also serves as a casing for the first valve body 30 and a valve seat. For this reason, the casing for exclusive use of the 1st valve body 30 and the seal member (O ring etc.) at the time of attaching this to piping become unnecessary. As a result, the number of parts of the entire check valve structure can be reduced as compared with the case where the first valve body 30 and the second valve body 40 are configured as individual check valves.

  In addition, since the space surrounded by the stepped portion of the pipe 71 and the end surface of the casing 50 is configured to directly communicate with the opening 74 of the pipe 71 connected to the air release valve, the first valve body 30 and the first It is not necessary to provide a spacer or the like for securing a flow path to the opening 74 between the two valve bodies 40. For this reason, the number of parts can be reduced as much as the spacer can be omitted, and the entire check valve structure can be made compact.

  Further, locking projections 36 are respectively provided on the shaft portions 34 of the first valve body 30 and the second valve body 40, while locking protrusions are respectively formed on the boss portions (sliding portions) 53 and 82 of the casing 50. The parts 53a and 82a are formed to prevent the valve bodies 30 and 40 from falling off the casing 50, and when necessary, a tensile force (external force) is applied to the valve bodies 30 and 40 to the casing 50. Can be easily removed. For this reason, when it comprises as the non-return valve unit 10, each valve body 30 and 40 can be hold | maintained stably and the assembly | attachment to the piping 71 becomes easy. Further, it is convenient to replace only the valve bodies 30 and 40.

  Further, a stepped portion 61 is formed in the rubber packing 60 provided at the tip of each valve body 30, 40 to form a gap with the flange portion 31. When each valve body 30, 40 is seated, a rubber is formed. The packing 60 can be elastically deformed in the vicinity of the corresponding valve seat. For this reason, even if the axial center of each valve body 30 and 40 shifts | deviates a little or inclines, the adhesiveness with a valve seat is securable.

And by incorporating the check valve structure configured in this way into the backflow prevention device, the whole backflow prevention device can also be manufactured more compactly and at a lower cost.
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the specific embodiment, and it can be changed and modified within the spirit of the present invention. Not too long.

  For example, in the above-described embodiment, the check valve structure according to the present invention is arranged at the position of the opening 74 that connects the atmosphere release valve 20 and the pipe 71. However, the check valve structure has the opening 74. You may arrange | position in the position away from.

  Moreover, in the said embodiment, although an example of the structure of the non-return valve unit 10 or the piping 71 was shown, the shape and structure of the 1st valve body 30 and the 2nd valve body 40, and the part which supports these are supported. Of course, the structure of the casing 50, the shape of the pipe 71, and the like can be appropriately changed in design as long as they have a similar function. For example, in the above embodiment, the first valve body 30 and the second valve body 40 have the same shape, but they may be configured in different shapes.

  Any structure can be applied as long as it is arranged in a pipe and has a plurality of check valves arranged in series that allow a flow in one direction to prevent a reverse flow of fluid and prohibit a flow in the reverse direction.

It is sectional drawing showing the structure of the backflow prevention apparatus concerning embodiment of this invention. It is an expanded sectional view showing composition of a check valve structure. It is an expanded sectional view showing composition of a check valve structure. It is explanatory drawing showing operation | movement of a backflow prevention apparatus. It is explanatory drawing showing operation | movement of a backflow prevention apparatus. It is explanatory drawing showing the structure of the conventional hot water supply system. It is sectional drawing showing the structure of the conventional backflow prevention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water supply pipe 6 Hot water supply pipe 7 Piping 8 Flow rate sensor 9 Solenoid valve 10 Check valve unit 14 Bath 20 Air release valve 30 1st valve body 31 Flange part 34 Shaft part 36 Locking protrusion 40 2nd valve body 50 Casing 53a Locking projection 55 Valve seat 60 Rubber packing 61 Stepped portion 71 Pipe 72 Stepped opening 73 Valve seat 74 Opening 80 Bearing member 82a Locking projection

Claims (1)

  A solenoid valve installed in a pipe connected from the hot water supply pipe to the bathtub to allow or block the flow of water in the pipe;
  A check valve structure that is disposed closer to the bathtub than the solenoid valve of the pipe and allows water to flow from the solenoid valve to the bathtub, but prevents reverse flow of water from the bathtub to the solenoid valve. When,
  An air release valve that is connected to an opening formed in a pipe wall of the pipe having the check valve structure and opens and closes to release water in the check valve structure to the atmosphere according to a pressure drop on the water supply side When,
  In the backflow prevention device comprising
  The check valve structure is configured to be able to be seated on a first valve seat formed of a step portion formed integrally with the pipe, and by being seated on the first valve seat in the pipe, the reverse direction of the fluid A first valve body that blocks the flow to the first valve body, a second valve body that is coaxially disposed behind the first valve body in the pipe, and a cylindrical shape that is fixed to the inner peripheral surface of the pipe The first valve body and the second valve body are slidably supported in the axial direction, and the second valve body is seated inside the main body, thereby allowing the fluid to flow. A casing formed integrally with a second valve seat for preventing flow in the reverse direction;
  In the first valve body and the second valve body, a locking projection protrudes at a predetermined position of a shaft portion that is slidably supported by the casing, while the locking projection projects the shaft portion. It is configured to be prevented from falling off from the casing by being engaged with a locking protrusion that protrudes inwardly at the tip end portion of the shaft support portion of the casing to be supported,
  A flange portion having an outer shape larger than the peripheral edge of the opening where the corresponding first and second valve seats are located at the distal ends of the first valve body and the second valve body, and the flange portion A plate-like rubber packing that is extrapolated and fixed to the first and second valve seat sides and has an outer shape larger than the peripheral edge of the opening, respectively.
  The rubber packing has a step portion that forms a predetermined gap with the flange portion by reducing the thickness of the outer peripheral portion including the vicinity of the contact position with the first and second valve seats, When the first and second valve bodies are seated, the stepped portion is bent toward the flange portion, and is in close contact with the first and second valve seats on the side opposite to the flange portion. And
  The opening of the pipe to which the atmosphere release valve is connected communicates with a space surrounded by the first valve seat of the pipe and the end surface of the casing on the side supporting the first valve body. It is comprised so that it may be made, The backflow prevention apparatus characterized by the above-mentioned.

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