Drain pipe structure

Abstract

To provide a drain pipe structure capable of properly opening and closing a vent valve.SOLUTION: A drain pipe structure comprises: a drain pipe having a drain trap for retaining a water seal, for draining water from plumbing fixtures; a vent valve communicating with the drain pipe downstream of the water seal, preventing fluid in the drain pipe from flowing out to the exterior and allowing intake of external air; a first pressure relief device communicating with the drain pipe downstream of the vent valve and buffering pressure in the drain pipe; and a second pressure relief device provided between the vent valve and the drain pipe to communicate therebetween and buffering pressure in the drain pipe. The second pressure relief device buffers a lower pressure than the first pressure relief device.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a drainage pipe structure. [Background technology]

[0002] 2. Description of the Related Art A drain pipe structure disclosed in Patent Document 1 is known in which a bag-shaped pressure relief device and a vent valve are provided as a relief device for relieving pressure in a drain pipe when a siphon is activated. Also, a drain pipe structure described in Patent Document 2 is known in which a vent valve is provided in the drain pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 2018-104967 [Patent Document 2] Publication No. 2021-95680 Summary of the Invention [Problem to be solved by the invention]

[0004] When the downstream side of the drainage becomes negative pressure, the vent valve takes in outside air and breaks the seal of the trap. In other words, the trapped seal water is sucked in downstream of the drainage direction by the negative pressure and disappears. It has the role of suppressing the leakage of odors, drawing in air during drainage to protect the trap's seal, and closing the valve under normal conditions to suppress the leakage of odors, etc. However, small, unintended pressure fluctuations in the drain pipe can cause the vent valve to open and close at unintended times, which can lead to air leaks in the piping.

[0005] In consideration of the above, the present disclosure aims to provide a drainage pipe structure that can properly open and close a vent valve. [Means for solving the problem]

[0006] The drain pipe structure of the first aspect comprises a drain pipe having a drain trap for storing seal water and for draining wastewater from plumbing equipment, a vent valve connected to the drain pipe downstream of the seal water and preventing the fluid in the drain pipe from flowing out to the outside and capable of taking in outside air, a first pressure relief device connected to the drain pipe downstream of the vent valve and buffering the pressure in the drain pipe, and a second pressure relief device provided between the vent valve and the drain pipe so as to communicate with the vent valve and the drain pipe and buffering the pressure in the drain pipe, wherein the second pressure relief device buffers pressure lower than that of the first pressure relief device.

[0007] In the drain pipe structure according to the first aspect, drainage water from a plumbing device is discharged through the drain trap and the drain pipe.

[0008] When negative pressure occurs inside the drain pipe downstream of the seal water, outside air is introduced into the drain pipe through the vent valve, relieving the negative pressure inside the drain pipe and preventing the seal water in the drain trap from leaking downstream and causing the drain trap to break.

[0009] If positive pressure occurs inside the drain pipe downstream of the seal water, there is a concern that the positive pressure will cause the seal water to flow upstream and break the drain trap. However, with this drain pipe structure, the positive pressure is buffered by the first pressure relief device, preventing the drain trap from breaking due to positive pressure.

[0010] However, if unintended minute pressure fluctuations occur inside the drain pipe and these pressure fluctuations act on the vent valve, the operation of the vent valve may become unstable, and there is a concern that air inside the drain pipe may be discharged to the outside through the vent valve.

[0011] In this drain pipe structure, a second pressure relief device capable of buffering a pressure lower than that of the first pressure relief device is provided between the vent valve and the drain pipe, so that the second pressure relief device suppresses pressure fluctuations that destabilize the operation of the vent valve and allows the vent valve to operate normally. This prevents air in the drain pipe from being discharged to the outside through the vent valve.

[0012] In addition, "operating normally" means preventing the fluid in the drain pipe from flowing out to the outside while allowing outside air to be taken in.

[0013] The drainage pipe structure of the second aspect is the drainage pipe structure of the first aspect, wherein the first pressure relief device is provided with a first expansion / contraction member that expands and contracts in response to fluctuations in the pressure, and the second pressure relief device is provided with a second expansion / contraction member that expands and contracts in response to fluctuations in the pressure, and the second expansion / contraction member is set to have a lower rigidity in the expansion / contraction direction than the first expansion / contraction member.

[0014] In the drain pipe structure of the second aspect, the second expansion / contraction member of the second pressure relief device, which is located upstream of the first pressure relief device, is set to have a lower rigidity in the expansion / contraction direction than the first expansion / contraction member of the first pressure relief device, so that pressure fluctuations acting on the air valve can be effectively suppressed.

[0015] A drainage pipe structure according to a third aspect is the drainage pipe structure according to the second aspect, wherein the second expansion / contraction member is a tubular member formed of an elastic body.

[0016] In the drain pipe structure according to the third aspect, the second expansion / contraction member is a tubular member, so that the drain pipe and the vent valve can be in communication with each other. Also, by making the second expansion / contraction member a tubular member made of an elastic body, the tubular member can be elastically expanded and contracted, so that pressure fluctuations in the drain pipe acting on the vent valve can be mitigated.

[0017] A drainage pipe structure according to a fourth aspect is the drainage pipe structure according to the third aspect, wherein the second expansion / contraction member is uneven in the circumferential direction.

[0018] The second expansion / contraction member of the drainage pipe structure of the fourth aspect is a tubular member that is circumferentially uneven, and therefore is more likely to expand and contract with small pressure fluctuations than a tubular member that is not circumferentially uneven, and can effectively mitigate small pressure fluctuations.

[0019] The drainage pipe structure of the fifth aspect is a drainage pipe structure of the fourth aspect, in which the second expansion member has a plurality of inner convex portions formed circumferentially therein that are convex radially inward, and the inner convex portions are curved so that the axial central portion is convex radially inward.

[0020] The second expansion / contraction member of the drainage pipe structure of the fifth aspect has multiple inner convex portions formed circumferentially which convex radially inward, and the inner convex portions are curved so that the axially central portions are convex radially inward, making them more susceptible to expansion and contraction due to pressure fluctuations compared to cases where the axially central portions of the inner convex portions are not curved so as to convex radially inward.

[0021] A drain pipe structure according to a sixth aspect is the drain pipe structure according to any one of the first to fifth aspects, further comprising a disposer provided upstream of the drain trap.

[0022] In the drain pipe structure according to the sixth aspect, as one example, food waste can be crushed in a disposer, and the crushed food waste can be discharged into the drain pipe together with wastewater. Furthermore, even if pressure fluctuations occur in the drain pipe due to the operation of the disposer, the pressure fluctuations are alleviated by the second pressure relief device, allowing the vent valve to operate normally.

[0023] A drain pipe structure according to a seventh aspect is any one of the drain pipe structures according to the first to sixth aspects, wherein the drain pipe is provided with a siphon drain pipe on the downstream side.

[0024] The drain pipe structure according to the seventh aspect is provided with a siphon drain pipe on the downstream side, so that drainage water from plumbing equipment can be sucked in by siphon force and efficiently discharged. Effect of the Invention

[0025] As described above, according to the drain pipe structure of the present disclosure, it is possible to properly open and close the vent valve. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a configuration diagram showing a drainage pipe structure according to a first embodiment. [Diagram 2] 2(A) is a cross-sectional view showing a first pressure relief device, and FIG. 2(B) is a cross-sectional view taken along line AA of the second pressure relief device shown in FIG. 2(A). [Diagram 3] FIG. 2 is a perspective view showing a first expansion member. [Figure 4] FIG. 4 is a cross-sectional view showing a second pressure relief device. [Diagram 5] FIG. 13 is a side view showing the second expansion member. [Figure 6] FIG. 13 is a top view showing the second expansion member. [Figure 7] 7 is a cross-sectional view of the pressure relief member shown in FIG. 6 taken along line 7-7. [Figure 8] 8 is a cross-sectional view of the pressure relief member shown in FIG. 6 taken along line 8-8. [Figure 9] FIG. 11 is a perspective view showing a second expansion member according to a second embodiment. [Figure 10] FIG. 13 is a top view showing a second expansion member according to a second embodiment. [Figure 11] 11 is a cross-sectional view of the second expansion member shown in FIG. 10 taken along line 11-11. [Figure 12] FIG. 11 is a perspective view showing a second expansion member according to a third embodiment. [Figure 13] FIG. 11 is a top view, partially in cross section, showing a second expansion member according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] [First embodiment] Hereinafter, a drainage pipe structure 10 according to a first embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. The drainage pipe structure 10 according to this embodiment is provided with a siphon drainage structure having a siphon drainage pipe 44, which will be described later.

[0028] The configuration of the connection parts of each pipe is omitted in Figure 1. The drainage standpipe 16 that penetrates the through hole 14 of the floor slab 12 of the building is provided with a drainage joint 18 that connects the pipes from the plumbing equipment, and is configured to merge the drainage from the upper drainage standpipe 16 and the drainage from the plumbing equipment.

[0029] (Overall configuration of drainage pipe structure) Each floor is provided with a kitchen sink 19 as a water-related appliance. A disposer 20 is attached to the kitchen sink 19. The disposer 20 of this embodiment has a jet flush function (also called jet washing) that quickly discharges wastewater that temporarily accumulates in the crushing chamber after crushing food waste. By storing water in the disposer 20, food waste adhering to the inside of the grinding chamber can be removed, and by discharging it all at once, the water flows with force, making it possible to clean the inside of the piping.

[0030] A drain trap 26 for storing seal water W is attached downstream of the disposer 20 in the drainage direction. The drain trap 26 of the present embodiment is, for example, a so-called S-trap. The drain trap 26 is also an example (part) of the drain pipe of the present invention. The drain trap 26 may have a structure other than an S-trap.

[0031] The drain trap 26 is provided with an air vent valve 36 downstream of the seal water W, via a second pressure relief device 74, which allows air from the outside to pass into the trap while preventing drainage and air from passing from the trap to the outside. Incidentally, since the ventilation valve 36 has a conventionally known structure, a description of the structure of the ventilation valve 36 will be omitted.

[0032] A drain joint 38 of the first pressure relief device 40 is connected to the downstream side in the drain direction of the drain trap 26 (downstream side of the seal water W), and a drain pipe 32 that flows wastewater downward is connected to the downstream side in the drain direction of the drain joint 38. This drain pipe 32 is an example of the drain pipe of the present disclosure.

[0033] A siphon drain pipe 44 is connected to the downstream side in the drain direction of the drain pipe 32. This siphon drain pipe 44 is also one example (part) of the drain pipe of the present invention. The siphon drain pipe 44 is configured to include a horizontal pull pipe 46 extending laterally along the floor slab 12, and a vertical pipe 48 provided downstream of the horizontal pull pipe 46 and extending downward along the drainage standpipe 16. The vertical pipe 48 is connected to the drainage standpipe 16 via a drainage joint 18.

[0034] In this siphon drain pipe 44, a siphon force is generated by causing wastewater that has flowed from the horizontal drain pipe 46 into the vertical pipe 48 to flow downward. The wastewater in the piping upstream of the vertical pipe 48, i.e., the horizontal drain pipe 46, the drain pipe 32, and the junction pipe 42, is pulled by the siphon force generated in the vertical pipe 48, and a siphon force acting in the discharge direction acts on the wastewater.

[0035] (Configuration of the first pressure relief device) Fig. 2(A) shows the cross-sectional shape of the first pressure relief device 40. As shown in Figs. 2(A) and (B), the first pressure relief device 40 includes a bag-shaped first expandable / contractable member 50 that communicates with the branch pipe portion 56 of the drain joint 38, and a cover 52 that covers the first expandable / contractable member 50.

[0036] As shown in Figures 1 and 2, the drain fitting 38 is formed with a main pipe section 54 connected to the lower end of the drain trap 26 and the upper end of the drain pipe 32, and a branch pipe section 56 extending diagonally upward from the middle of the main pipe section 54.

[0037] The main pipe 54 is formed in a cylindrical shape. A large diameter portion 58 having a large diameter is formed at the lower portion of the main pipe 54. A male thread portion 58A is formed on the outer circumferential surface of the lower end side of the large diameter portion 58, and is configured so that the above-mentioned drain pipe 32 can be connected.

[0038] In addition, a large diameter section 60 is formed at the upper part of the main pipe section 54, and a male thread section 60A is formed on the outer surface at the upper end side of the large diameter section 60, so that the aforementioned drain trap 26 can be connected.

[0039] The branch pipe section 56 is also formed in a cylindrical shape and communicates with the main pipe section 54. A funnel section 57 that gradually expands in diameter upward is integrally provided on the upper end side of the branch pipe section 56. As shown in Fig. 2(A), the upper end of the funnel section 57 forms a large-diameter cylindrical mounting section 62, and the first expansion / contraction member 50 and the cover 52 that houses the first expansion / contraction member 50 are attached to this mounting section 62.

[0040] As shown in Figs. 2 and 3, the first expandable / contractable member 50 is formed in a cylindrical shape with a closed upper portion and an open lower portion, from an elastic material such as rubber.

[0041] The first expansion / contraction member 50 is configured to receive pressure from the inside of the lower portion of the drain pipe 32. The first expansion / contraction member 50 is formed in a cup shape with one end (upper end) of a cylindrical main body portion 51 closed by a top portion 66.

[0042] A base end 51A of the main body 51 of the first expansion / contraction member 50 is formed in an annular shape, and an opening for opening the first expansion / contraction member 50 is formed therein.

[0043] The first expansion / contraction member 50 has three vertical direction maintaining portions 68 extending linearly from the base end side to the tip end side at equal intervals in the circumferential direction as an example of a shape maintaining portion. The vertical direction maintaining portions 68 are formed thicker so that they are slightly harder than other portions during molding, and serve to allow the first expansion / contraction member 50 to stand on its own in a free state.

[0044] A lateral direction maintaining portion 70, which is an example of a shape maintaining portion, is formed on the top portion 66 of the first expandable / contractable member 50. This lateral direction maintaining portion 70 is formed thick so that it is slightly harder than other portions during molding, and is elastically deformable, but is configured so as to be able to maintain its shape in a free state.

[0045] When viewed in a plane, the lateral maintaining portion 70 is formed in a triangular shape that radially extends outward from the center, and each apex 70A of the lateral maintaining portion 70 is formed in a tapered shape and is configured to be continuous with the tip of the vertical maintaining portion 68. As a result, the first expansion / contraction member 50 maintains the shape shown in FIG. 3 in a free state.

[0046] On the peripheral surface of this first expansion / contraction member 50, between adjacent vertical direction maintaining portions 68, there are formed expansion / contraction portions 72 which are more flexible and more easily elastically deformed than the vertical direction maintaining portions 68. Each expansion / contraction portion 72 is configured to expand and contract in the horizontal direction when subjected to pressure from the drain pipe 32. Here, the "horizontal direction" in which the expansion / contraction portions 72 expand and contract is a direction perpendicular to the self-supporting direction (vertical direction) of the first expansion / contraction member 50 maintained in a self-supporting state.

[0047] When the inside of the first expansion / contraction member 50 receives positive pressure from the drain pipe 32, the expansion / contraction section 72 elastically deforms so as to expand laterally, thereby temporarily retaining the gas supplied to the first expansion / contraction member 50 from the drain pipe 32 and relieving the pressure generated in the drain pipe 32.

[0048] 2(A), a male mounting thread 62B is formed on the outer periphery of the mounting portion 62, and a female mounting thread 64C is formed on the inner circumferential surface of the lower end portion of the cover 52. The first expansion / contraction member 50 and the cover 52 are attached to the mounting portion 62 by screwing the female mounting thread 64C into the male mounting thread 62B.

[0049] A plurality of ventilation holes 64E are formed in the top surface 64A of the cover 52. This makes it possible to suppress a change in the internal pressure inside the cover 52 when the first expansion / contraction member 50 expands / contracts.

[0050] (Configuration of the second pressure relief device) As shown in FIG. 4, a connecting pipe portion 26B for connecting a second pressure relief device 74 is provided on an upper portion of the downstream curved portion 26A of the drain trap 26. The connection pipe portion 26B extends upward, and has a male screw 76 formed on the outer periphery of the upper end side.

[0051] The second pressure relief device 74 includes a cylindrical main body 78 and a cylindrical second expansion and contraction member 80 disposed inside the main body 78 .

[0052] The main body 78 has a cylindrical portion 78A, and a large diameter portion 78B having a larger diameter than the cylindrical portion 78A is formed integrally with the cylindrical portion 78A on the lower end side of the cylindrical portion 78A.

[0053] A male screw 82 is formed on the outer circumferential surface of the upper end side of the cylindrical portion 78A, and a female screw 83 is formed on the inner circumferential surface of the large diameter portion 72B.

[0054] The female screw 36A of the vent valve 36 is screwed into the male screw 82 of the main body 78, thereby connecting the vent valve 36 to the main body 78. In addition, the male screw 76 of the drain trap 26 is screwed into the female screw 83 of the main body 78, thereby connecting the main body 78 to the drain trap 26.

[0055] As shown in Figures 5 to 8, the second expansion / contraction member 80 is formed generally in a cylindrical shape from an elastic material such as rubber, with an upper ring portion 80A for clamping and fixing formed at the upper end and a lower ring portion 80B for clamping and fixing formed at the lower end, and a thin-walled expansion / contraction portion 84 formed between the upper ring portion 80A for clamping and fixing and the lower ring portion 80B for clamping and fixing.

[0056] The drain trap 26 and the vent valve 36 are connected to each other through the internal space of the second expansion / contraction member 80 which is formed in a cylindrical shape.

[0057] 6, the expansion / contraction portion 84 has a plurality of inner convex portions 84A formed in the circumferential direction, which are convex radially inward. In other words, the expansion / contraction portion 84 is uneven in the circumferential direction, and the radius changes periodically in the circumferential direction.

[0058] 7, the radial distance r of the inner convex portion 84A measured radially outward from the axis CL of the second expansion / contraction member 80 to the radially inner apex (ridge) of the inner convex portion 84A gradually decreases from both axial ends toward the axial middle side. In other words, the shape of the radially inner apex (ridge) of the inner convex portion 84A is curved. In other words, the inner convex portion 84A is curved such that the axial center portion is convex radially inward.

[0059] In addition, as shown in the cross-sectional view of Figure 8, the convex portion 84B, which is between the inner convex portions 84A and is convex in the opposite direction to the inner convex portion 84A, has a radial distance R measured radially outward from the axis CL of the second expansion member 80 to the radially outer apex (ridge) of the convex portion 84B, which is approximately constant along the axial direction (more specifically, the radius of the axial center portion is slightly smaller than the radius of both axial ends).

[0060] Here, the differences between the first expandable / contractable member 50 of the first pressure relief device 40 and the second expandable / contractable member 80 of the second pressure relief device 74 will be described. Both the first expansion / contraction member 50 and the second expansion / contraction member 80 are formed of an elastic body so as to be expandable and contractible, but the second expansion / contraction member 80 is set to have lower rigidity in the expansion / contraction direction than the first expansion / contraction member 50. In other words, the second expansion / contraction member 80 is configured to deform under a smaller pressure than the first expansion / contraction member 50.

[0061] (Action, effect) The operation and effects of the drainage pipe structure 10 of this embodiment having the above configuration will be described. When wastewater is discharged from the disposer 20, the wastewater is discharged to the drainage standpipe 16 via the drain trap 26, the drain pipe 32, and the siphon drain pipe 44. When the wastewater flows into the standpipe 48 and falls in the standpipe 48 in a full flow state, a siphon force is generated, and the wastewater is efficiently discharged to the drainage standpipe 16.

[0062] Incidentally, when the pressure downstream of the drain trap 26 becomes higher than atmospheric pressure, in other words, when positive pressure occurs, the air downstream of the drain trap 26 pushes the seal water W from the downstream side, causing the seal water W to flow back upstream. However, when positive pressure occurs inside the drain pipe downstream of the seal water W, the air inside the drain pipe 32 flows into the first pressure relief device 40 via the drain joint 38, and the first expansion / contraction member 50 expands laterally to relieve the positive pressure, in other words, the pressure acting on the seal water W from the downstream side becomes smaller than when the first pressure relief device 40 is not present, and the opening of the drain trap 26 due to the positive pressure is suppressed.

[0063] In addition, since the vent valve is closed except when negative pressure is applied, the air (odor) downstream of the drain trap is prevented from being discharged to the outside via the vent valve .

[0064] On the other hand, when the siphon force acts and negative pressure occurs in the drain pipe downstream of the seal water W of the drain trap 26, outside air flows into the downstream side of the seal water W of the drain trap 26 through the vent valve 36, suppressing excessive pressure drop in the drain pipe downstream of the seal water W, and thus suppressing the breakage of the drain trap 26 due to negative pressure.

[0065] Incidentally, when the siphon force is acting to drain water (there is negative pressure inside the drain pipe), for example, if the jet flush function of the disposer 20 is activated and the wastewater is discharged from the disposer 20 all at once, positive pressure may act instantaneously on the downstream side of the disposer 20, causing slight fluctuations in the pressure acting on the vent valve 36.

[0066] If the pressure acting on the vent valve 36 fluctuates slightly and the opening and closing action of the vent valve 36 becomes unstable, there is a concern that air inside the drain pipe will leak through the vent valve 36 to the outside.

[0067] However, in this embodiment, the second expansion / contraction member 80 expands and contracts to suppress, in other words, mitigate, the minute pressure fluctuations acting on the vent valve 36, thereby allowing the vent valve 36 to operate stably and preventing air in the drain pipe from leaking to the outside through the vent valve 36.

[0068] In addition, a first pressure relief device 40 capable of buffering pressure fluctuations is provided downstream of the disposer 20, while the second pressure relief device 74 is provided in series adjacent to the vent valve 36 upstream of the first pressure relief device 40, and is equipped with a second expansion / contraction member 80 that is easier to expand and contract than the first expansion / contraction member 50 of the first pressure relief device 40, so that minute pressure fluctuations acting on the vent valve 36 can be effectively suppressed.

[0069] In this embodiment, the expansion / contraction section 84 is made uneven in the circumferential direction to make it easier to expand and contract the second expansion / contraction member 80. However, in order to deform with less pressure than the first expansion / contraction member 50, the volume of the expansion / contraction section 84, the hardness, thickness, uneven shape, etc. can be adjusted.

[0070] [Second embodiment] Next, a second expansion / contraction member 88 used in the drainage pipe structure 10 according to the second embodiment of the present disclosure will be described with reference to Fig. 9 to Fig. 11. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

[0071] As shown in Figures 9 to 11, the second expansion / contraction member 88 of this embodiment has a different shape from the second expansion / contraction member 80 of the first embodiment, and has a rectangular cylindrical expansion / contraction section 90 between an upper ring portion 80A for clamping and a lower ring portion 80B for clamping and fixing, the expansion / contraction section 90 being composed of a pair of flat first wall portions 90A and a pair of flat second wall portions 90B formed narrower than the first wall portions 90A.

[0072] In the second expansion / contraction member 80 of this embodiment, when a pressure change occurs, the first wall portion 90A and the second wall portion 90B deform, and the positive pressure can be relieved, similar to the second expansion / contraction member 80 of the first embodiment.

[0073] [Third embodiment] Next, a second expansion / contraction member 92 used in the drainage pipe structure 10 according to the third embodiment of the present disclosure will be described with reference to Fig. 12 and Fig. 13. Note that this embodiment is a modified example of the second embodiment, and the same components as those in the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0074] As shown in Figs. 12 and 13, in the second expansion / contraction member 92 of this embodiment, a rib 94 that extends along the axial direction and protrudes inward is formed in the widthwise center of the inner surface of the first wall portion 90A.

[0075] When negative pressure acts on the second expansion / contraction member 80, one first wall portion 90A and the other first wall portion 90A opposing each other deform in a direction approaching each other. However, since the first wall portion 90A has a rib 94 that protrudes inward and hits the opposing first wall portion 90A, the one first wall portion 90A and the other first wall portion 90A are prevented from coming into close contact with each other, which would make it difficult for air to flow inside the square tube.

[0076] [Other embodiments] While one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above, and it goes without saying that the present disclosure can be implemented in various modified forms without departing from the spirit and scope of the present disclosure.

[0077] In the first embodiment, the second expansion / contraction member 80 had a cylindrical shape with projections and recesses in the circumferential direction, but the second expansion / contraction member 80 may be formed into a cylindrical shape of a constant diameter or into a shape other than a cylindrical shape as long as the second expansion / contraction member 80 is formed into a cylindrical shape of a constant diameter as needed.

[0078] In the above embodiment, a disposer 20 is provided, but the disposer 20 may be provided as necessary and does not necessarily have to be provided.

[0079] In the drainage pipe structure 10 of the above embodiment, a siphon drainage pipe 44 is provided, but the siphon drainage pipe 44 may be provided as needed, and instead of the siphon drainage pipe 44, a normal sloped piping may be provided. [Explanation of symbols]

[0080] 10...Drain pipe structure, 19...Kitchen sink (water-related equipment), 20...Disposer, 26...Drain trap, 32...Drain pipe, 36...Vent valve, 40...First pressure relief device, 44...Siphon drain pipe, 50...First expansion / contraction member, 74...Second pressure relief device, 80...Second expansion / contraction member, 84A...Inner convex portion

Claims

1. a drainage pipe having a drainage trap for storing sealing water and for draining water from a water-related device; A vent valve that is connected to the drain pipe downstream of the seal water and prevents the fluid in the drain pipe from flowing out to the outside and can take in outside air; A first pressure relief device that communicates with the drain pipe downstream of the vent valve and buffers pressure in the drain pipe; a second pressure relief device provided between the vent valve and the drain pipe so as to communicate with the vent valve and the drain pipe, the second pressure relief device buffering the pressure in the drain pipe; Equipped with The second pressure relief device buffers a lower pressure than the first pressure relief device. Drainage pipe structure.

2. The first pressure relief device includes a first expansion / contraction member that expands and contracts in response to the change in pressure, The second pressure relief device includes a second expansion / contraction member that expands and contracts in response to the change in pressure, The second expansion / contraction member is set to have a lower rigidity in the expansion / contraction direction than the first expansion / contraction member. The drainage pipe structure according to claim 1.

3. The second expansion / contraction member is a tubular member formed of an elastic body. The drainage pipe structure according to claim 2.

4. The second expansion / contraction member is uneven in the circumferential direction. The drainage pipe structure according to claim 3.

5. The second expansion / contraction member has a plurality of inner convex portions formed in a circumferential direction, the inner convex portions being convex radially inward, The inner convex portion is curved so that an axial center portion thereof is convex toward the radially inward direction. The drainage pipe structure according to claim 4.

6. A disposer is provided upstream of the drain trap. The drainage pipe structure according to claim 1.

7. The drain pipe is provided with a siphon drain pipe downstream. The drainage pipe structure according to claim 1.

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