Backflow prevention joint

Abstract

To provide a backflow prevention fitting capable of being installed between the upstream drain pipe and the downstream drain pipe having a height difference capable of easily conducting internal inspections and the like.MEANS FOR SOLVING THE PROBLEM: A disclosed backflow prevention fitting includes: an inlet having the first central axis extending horizontally; an outlet having a second central axis extending vertically; a body connecting the inlet and the outlet; a valve seat formed inside the body; a valve body supported by the valve seat so as to open and close with respect thereto; an inspection port that extends from the body and has a third central axis extending diagonally upward away from the inlet; and a lid that is detachably attached to the inspection port.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a backflow prevention joint that includes a check valve (valve body) inside and connects a horizontally extending drain pipe and a vertically extending drain pipe. In particular, it relates to a backflow prevention joint with a check valve that includes a body portion that connects a horizontally extending inlet and a vertically extending outlet, and the body portion has an inspection port that extends in an upwardly inclined direction away from the inlet.

Background Art

[0002] Generally, the drainage discharged from drainage facilities such as toilets, bathrooms, and kitchens in houses, etc., is collected in a drainage sump installed within the site via drain pipes connected to each drainage facility, and the drainage collected in the drainage sump flows out into the main sewer pipe via a public sump or a manhole. [[ID=~]] [[ID=~]]

[0003] [[ID=~]] Further, in order to prevent the intrusion of backflow water generated in downstream drainage facilities such as the main sewer pipe into the house, for example, as described in Japanese Patent Application Laid-Open No. 2020-153508 (Patent Document 1), a backflow prevention device attached to the inlet of a drainage sump or the like is widely known. [[ID=~]] [[ID=~]]

[0004] [[ID=~]] On the other hand, in recent years, due to the occurrence of abnormal weather associated with global warming and the like, cases where a large amount of rainwater flows into the main sewer pipe in a short period of time have been frequent. Therefore, in order to more effectively prevent the backflow of rainwater and the like, for example, as described in Japanese Patent Application Laid-Open No. 2021-169701 (Patent Document 2), a drainage sump or a vertical pipe is provided between an upstream drain pipe and a downstream drain pipe having a height difference, and a backflow prevention device as described in Patent Document 1 is attached to the outlet of the upstream drain pipe. The number of such cases is also increasing. [[ID=~]]

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, when attempting to install a backflow prevention device, such as the one described in Patent Document 1, at the connection point between an upstream drainage pipe and a downstream drainage pipe with a difference in elevation, it becomes necessary to install a drainage manhole or vertical pipe for the backflow prevention device at that location, resulting in a complex configuration and large-scale construction work.

[0007] Furthermore, when attempting to install a backflow prevention device as described in Patent Document 1 by providing drainage manholes or vertical pipes, there is a problem in that the drainage manholes or vertical pipes must be made larger than the size determined by the drainage flow rate in order to secure space for the movement of the check valve. Moreover, since backflow prevention devices are generally installed near the wall surface of drainage manholes or vertical pipes, even if inspection openings are provided at the top of them, they cannot be easily accessed (see Figure 2 in Patent Document 2), which causes problems in maintenance and other operations.

[0008] Therefore, the present invention aims to provide a backflow prevention joint (backflow prevention device) that can be easily installed between an upstream drain pipe and a downstream drain pipe with a difference in elevation, without the need to install drain manholes or vertical pipes, and that functions as a check valve while also allowing for easy maintenance such as internal inspection and cleaning. [Means for solving the problem]

[0009] The inventors diligently studied the piping layout and the structure of the check valve (valve body) when installing a backflow prevention joint (backflow prevention device) at the connection point between an upstream drain pipe and a downstream drain pipe with a difference in elevation. As a result, they discovered that by using a joint equipped with an inlet that opens horizontally to connect to the upper drain pipe on the upstream side and an outlet that opens vertically to connect to the lower drain pipe on the downstream side, and by installing a check valve (valve body) in between, and further arranging the inspection port at an angle, it is possible to solve the above problems by securing space for the movement of the check valve (valve body) without requiring the installation of drain manholes or vertical pipes, and without unnecessarily increasing the size of the backflow prevention joint, thus completing the present invention.

[0010] In other words, the present invention provides a backflow prevention joint comprising: an inlet having a first central axis extending horizontally; an outlet having a second central axis extending vertically; a body connecting the inlet and the outlet; a valve seat formed inside the body; a valve body supported so as to be openable and closable with respect to the valve seat; an inspection port having a third central axis extending from the body and extending upward diagonally away from the inlet; and a cover that is detachably attached to the inspection port.

[0011] The backflow prevention joint of the present invention has an inlet that opens horizontally and an outlet that opens vertically, so it can be easily connected directly or via an elbow pipe or the like between an upstream drain pipe and a downstream drain pipe that have a difference in elevation. Moreover, since the backflow prevention joint of the present invention is equipped with a valve body and a valve seat that function as a check valve, when connected between an upstream drain pipe and a downstream drain pipe, it also functions as a backflow prevention device.

[0012] Thus, the backflow prevention joint of the present invention can be easily installed between an upstream drain pipe and a downstream drain pipe that have a difference in elevation. Therefore, because there is a difference in elevation, it can more effectively prevent backflow of wastewater and the rise of backflow water than conventional backflow prevention devices that are installed between upstream and downstream drain pipes that do not have a difference in elevation and are at approximately the same level.

[0013] Furthermore, the backflow suppression joint of the present invention is equipped with an inspection port that extends diagonally upward from the body of the joint and away from the inlet, so as to ensure sufficient space for the check valve to move without unnecessarily increasing the size of the backflow suppression joint, and as the valve body and valve seat can be easily accessed through the inspection port, maintenance can be easily performed.

[0014] In this specification, "horizontal" does not mean only the horizontal direction in a strict sense, but is used to include a range that includes a degree of gradient provided when drainage is directed horizontally. Similarly, "vertical" does not mean only the vertical direction in a strict sense, but is used to include a range that includes a degree of error that occurs during the manufacturing and installation of joints.

[0015] In this invention, from the viewpoint of preventing the joint body from becoming unnecessarily large and ensuring space for the valve body to move downstream, it is preferable that the diameter of the inspection port is the same as the diameter of the outlet. Furthermore, the diameter of the outlet may be the same as the diameter of the inlet, but it is preferable that it be larger than the diameter of the inlet. Therefore, when the diameter of the outlet is the same as the diameter of the inspection port, the diameter of the inspection port will also be larger than the diameter of the inlet.

[0016] In this specification, "identical" bore diameter does not mean that the bore diameters are exactly the same, but rather includes a range in which the inner diameter of one and the outer diameter of the other, or the outer diameter of one and the inner diameter of the other, are approximately the same, including manufacturing tolerances.

[0017] In this invention, it is preferable that the valve body is rotatably supported on the cover of the inspection port. When the valve body is attached to the cover, the valve body can be removed together with the cover, and the inside of the joint after the valve body has been removed can be made substantially hollow, making maintenance such as inspection and cleaning of the inside of the joint easier.

[0018] In the present invention, the lid is preferably composed of a cap portion that is not rotatably attached to the inspection opening in the circumferential direction, and a lid body that is rotatably attached to the inspection opening in the circumferential direction on the cap portion, and the valve body is preferably supported by the cap portion.

[0019] Furthermore, when the lid is composed of a lid body and a cap portion as described above, it is preferable that a first engaging portion is provided on the inner circumferential surface of the inspection opening to fix the cap portion so that it cannot rotate circumferentially relative to the inspection opening, and that a second engaging portion is provided on the cap portion to engage with the first engaging portion, so that the valve body can be easily set in the predetermined position.

[0020] Furthermore, if the valve body is attached to the cover, and the cover becomes detached from the inspection port for any reason, the valve body will also come off, making it impossible to prevent backflow of wastewater. For this reason, in the present invention, it is preferable to have a locking mechanism to prevent the cover from becoming detached from the inspection port due to an increase in the pressure of water or air inside the joint. The locking mechanism can be, for example, a bayonet mechanism that allows for arbitrary selection of engagement and disengagement between the cover and the inspection port by rotating the cover circumferentially relative to the inspection port.

[0021] Furthermore, using a bayonet mechanism as a locking mechanism for the lid not only prevents the lid from unintentionally detaching, but also allows the cap to be secured by being sandwiched between the lid body and the inspection opening. This ensures that the valve body supported by the cap is precisely set in its designated position without any looseness.

[0022] In this invention, since the outlet is positioned perpendicular to the inlet, in order to reliably and smoothly deflect the wastewater that flows horizontally from the inlet into the joint downward, it is preferable that the backflow prevention joint is provided with a valve pipe that communicates with the inlet and protrudes into the body, and that the valve seat is formed at the open end of the valve pipe. The valve pipe only needs to be provided so that all or part of its circumferential direction protrudes into the body.

[0023] In addition, the valve body maintains a slightly open state during normal times, allowing the flow of forward drainage even when the drainage volume is small, thereby preventing drainage blockage caused by foreign objects or the like. Therefore, it is preferable that the opening end of the valve pipe is inclined so as to approach the inlet as it goes from the upper part to the lower part.

Advantages of the Invention

[0024] According to the present invention, there is provided a backflow prevention joint including an inlet having a first central axis extending in the horizontal direction, an outlet having a second central axis extending in the vertical direction, a body portion connecting the inlet and the outlet, a valve seat portion formed inside the body portion, a valve body supported to be openable and closable with respect to the valve seat portion, an inspection port extending from the body portion and having a third central axis extending obliquely upward in a direction away from the inlet, and a lid portion detachably attached to the inspection port.

[0025] Since the backflow prevention joint of the present invention has an inlet extending in the horizontal direction and an outlet extending in the vertical direction, it can be easily connected between an upstream drain pipe and a downstream drain pipe having a height difference. Moreover, since the backflow prevention joint of the present invention includes a valve body and a valve seat portion that function as a check valve therein, when connected between the upstream drain pipe and the downstream drain pipe, the function as a backflow prevention device can also be obtained at the same time.

[0026] Thus, the backflow prevention joint of the present invention can be easily attached between an upstream drain pipe and a downstream drain pipe having a height difference. Therefore, due to the height difference, it is more effective in preventing the backflow of drainage and the rise of backflow water than a backflow prevention device attached between upstream and downstream drain pipes at substantially the same level without the conventional height difference.

[0027] Furthermore, since the backflow prevention joint of the present invention includes an inspection port extending from the body portion in the middle of the joint body and extending obliquely upward in a direction away from the inlet, it is possible to secure a movable space for the check valve without unnecessarily increasing the size of the backflow prevention joint, and since it is possible to easily access the valve body, the valve seat portion, etc. through the inspection port, maintenance and the like can be easily carried out. [Brief explanation of the drawing]

[0028] [Figure 1] This is a perspective view of a backflow prevention joint according to one embodiment of the present invention, as seen from the inspection port side. [Figure 2] Figure 1 is a perspective view of the backflow prevention joint shown from the inlet side. [Figure 3] Figures 1 and 2 are side views of the backflow suppression joint. [Figure 4] Figures 1 and 2 are front views of the backflow suppression joint. [Figure 5] Figures 1 and 2 show the rear view of the backflow suppression joint. [Figure 6] Figures 1 and 2 are plan views of the backflow prevention joint. [Figure 7a] Figure 6 is a cross-sectional view of the backflow suppression joint shown, taken at section AA. [Figure 7b] Figure 7a is a cross-sectional view of another application example of the backflow suppression joint shown. [Figure 7c] Figure 7a is a cross-sectional view of another application example of the backflow suppression joint shown. [Figure 7d] Figure 7a is a cross-sectional view of another application example of the backflow suppression joint shown. [Figure 8] This is a perspective view from above of the cover and valve body of a backflow suppression joint according to the first embodiment of the present invention. [Figure 9] Figure 8 is a perspective view of the lid and valve body from below. [Figure 10] Figures 8 and 9 are front views of the lid and valve body. [Figure 11] Figures 8 and 9 are side views of the lid and valve body. [Figure 12] Figures 8 and 9 show exploded views of the lid and valve body. [Modes for carrying out the invention]

[0029] A backflow suppression joint according to one embodiment of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and various modifications are possible without departing from the technical spirit of the present invention.

[0030] Figure 1 shows a perspective view of the backflow suppression joint 1 according to one embodiment of the present invention, viewed from the inspection port 7 side. Figure 2 shows a perspective view of the backflow suppression joint 1 shown in Figure 1, viewed from the inlet 2 side. Figure 3 shows a side view of the backflow suppression joint 1 shown in Figure 1. Figure 4 shows a front view of the backflow suppression joint 1 shown in Figure 1. Figure 5 shows a rear view of the backflow suppression joint 1 shown in Figure 1. Figure 6 shows a plan view of the backflow suppression joint 1 shown in Figure 1. Figure 7a shows a cross-sectional view of the backflow suppression joint 1 shown in Figure 6, cut along section AA.

[0031] As shown in Figures 1-6 and 7a, the backflow suppression joint 1 of this embodiment comprises a joint body 10 consisting of an inlet 2, an outlet 3, a body 4 connecting the inlet 2 and the outlet 3, and an inspection port 7 provided in the body 4, and a cover 8 that can be detachably attached to the inspection port 7. Furthermore, a valve pipe 5 is provided in the body 4 so as to communicate with the inlet 2 and protrude into the interior of the body 4, a valve seat 50 is formed at the open end of the valve pipe 5, and a valve body 6 is supported inside the body 4 so as to be able to open and close relative to the valve seat 50. The backflow suppression joint 1 according to one embodiment of the present invention will be described in detail below, divided into the joint body 10, the cover 8, and the valve body 6.

[0032] <Fitting body> In this embodiment, the joint body 10 includes an inlet 2 that opens horizontally and has a first central axis a extending horizontally, and an outlet 3 that opens vertically and has a second central axis b extending vertically. In this embodiment, the inlet 2 has a socket shape, and the outlet 3 has a spigot shape. Therefore, a socket step portion 20 is formed inside the inlet 2, which functions as a stopper when the tip of the connected drain pipe abuts against it. In this embodiment, the inlet 2 has a socket shape and the outlet 3 has a spigot shape, but the shapes of the inlet 2 and outlet 3 are not limited to this combination, and either the inlet shape or the spigot shape may be used for both.

[0033] As described above, the backflow prevention joint 1 of this embodiment is equipped with an inlet 2 that opens horizontally and an outlet 3 that opens vertically, so it can be easily connected between an upstream drain pipe and a downstream drain pipe (not shown) that have a difference in elevation. For example, if the upstream drain pipe extends horizontally and the downstream drain pipe extends vertically, the backflow prevention joint 1 can be directly connected between them. If both the upstream and downstream drain pipes extend horizontally while having a difference in elevation, the backflow prevention joint 1 can be connected between them by attaching an elbow pipe or the like to the outlet 3.

[0034] Furthermore, since the backflow prevention joint 1 of this embodiment can be easily installed between an upstream drain pipe and a downstream drain pipe that have a difference in elevation, it can more effectively prevent backflow of wastewater and the rise of backflow water than conventional backflow prevention devices that are installed between upstream and downstream drain pipes that do not have a difference in elevation and are at approximately the same level.

[0035] In this embodiment, the inspection port 7 has a third central axis c that extends diagonally upward so as it moves away from the inlet 2, and extends diagonally upward from the body 4 to form an opening. The upper part of the inspection port 7 has the shape of a receiving port, and a stepped portion 70 is formed for detachably supporting the lid portion 8, which will be described later. In addition, a concave first engaging portion 71 is provided on the inner circumferential surface of the inspection port 7 for supporting the lid portion 8 from below and fixing it so that it cannot rotate in the circumferential direction (see Figures 2, 3, and 5).

[0036] As described above, in this embodiment, the inspection port 7 is positioned diagonally upward, so unlike conventional horizontal backflow prevention devices, the drainage inside the joint does not easily overflow even when the cover 8 is opened. Also, by removing the cover 8, the inside of the joint body 10 can be easily accessed, making maintenance and other procedures easy. Furthermore, the inspection port 7 can be effectively utilized as the movable area of ​​the valve body 6, which will be described later, so that the movable space of the valve body 6 can be secured without unnecessarily increasing the size of the backflow prevention joint 1.

[0037] Therefore, in this embodiment, it is preferable that the diameter of the inspection port 7 is the same as the original diameter of the outlet port 3. In particular, by making the diameter of the inspection port 7 the same as the original diameter of the outlet port 3, a movable space for the valve body 6 can be formed on the downstream side (opening side) of the valve body 6 using the inspection port 7. This eliminates the need to provide extra space for the movement of the valve body 6, and allows for an efficient size in which the width of the outlet port 3 and the width of the joint body 10 are approximately the same. Note that "original diameter" refers to the diameter of the inlet port 2 and outlet port 3 when no adapters or the like are attached to the receiving port or spigot port to adjust their diameters.

[0038] On the other hand, the original diameter of outlet 3 may be the same as the original diameter of inlet 2. However, usually the diameters of the upstream and downstream drain pipes are the same, or the diameter of the downstream drain pipe is larger than that of the upstream drain pipe. Therefore, by using an adapter to adjust the diameter, the original diameter of outlet 3 can be made larger than the original diameter of inlet 2, thereby expanding the range of application of the backflow prevention joint 1. As mentioned above, when the original diameter of outlet 3 is the same as the diameter of inspection port 7, the diameter of inspection port 7 will also be larger than the diameter of inlet 2.

[0039] Figure 7a shows a cross-sectional view of a backflow suppression joint 1 in which a first reducing increaser 30 is attached only to the outlet 3 to reduce its diameter to the same as the diameter of the inlet 2. Figure 7b shows a cross-sectional view of a backflow suppression joint 1 in which, as a first application example of the backflow suppression joint 1 shown in Figure 7a, a reducing socket 21 is attached to the inlet 2 to reduce its diameter, and a second reducing increaser 31 is attached to the outlet 3 to adjust (reduce) its diameter to the same as the reduced diameter of the inlet 2.

[0040] As shown in Figures 7a and 7b, in this embodiment, the original diameter of the outlet 3 of the backflow prevention joint 1 is larger than the original diameter of the inlet 2. Therefore, when installing the backflow prevention joint 1 of this embodiment between an upstream drain pipe (not shown) whose downstream end diameter is the same as the original diameter of the inlet 2 and which opens horizontally, and a downstream drain pipe (not shown) whose upstream end opens vertically, the inlet 2 can be connected directly to the upstream drain pipe, and only the outlet 3 can be fitted with a first reducing insert 30 to adjust (reduce) its original diameter to match the diameter of the downstream drain pipe, in other words, the original diameter of the inlet 2, and then the downstream drain pipe can be connected (Figure 7a). Also, if the outlet 3 can be connected directly to the downstream drain pipe, it is not necessary to use the first reducing insert 30.

[0041] Furthermore, in the case of an upstream drain pipe (not shown) and a downstream drain pipe (not shown) with the same layout as in Figure 7a, if the diameter of either drain pipe is smaller than the original diameter of the inlet 2 and the original diameter of the outlet 3, then a reducing socket 21 can be attached to the inlet 2 to adjust (reduce the diameter) its original diameter to match the diameter of the upstream drain pipe and connect it to the upstream drain pipe, and a second reducing increaser 31 can be attached to the outlet 3 to adjust (reduce the diameter) its original diameter to match the diameter of the downstream drain pipe, in other words, the diameter of the inlet 2 reduced by the reducing socket 21 and connect it to the downstream drain pipe (Figure 7b). Also, if the outlet 3 can be connected directly to the downstream drain pipe, it is not necessary to use the second reducing increaser 31.

[0042] Figure 7c shows a cross-sectional view of a backflow suppression joint 1 as a third application example of the backflow suppression joint 1 shown in Figure 7a, in which a first reducing 45° elbow 32 is attached only to the outlet 3 to reduce its diameter and change the direction of outflow. Figure 7d shows a cross-sectional view of a backflow suppression joint 1 as a fourth application example of the backflow suppression joint shown in Figure 7a, in which a reducing socket 21 is attached to the inlet 2 to reduce its diameter, and a second reducing 45° elbow 33 is attached to the outlet 3 to reduce its diameter and change the direction of outflow.

[0043] When installing the backflow suppression joint 1 of this embodiment between an upstream drain pipe (not shown) whose downstream end diameter is the same as the original diameter of the inlet 2 and which opens horizontally, and a downstream drain pipe (not shown) whose upstream end opens diagonally upward, the inlet 2 is connected directly to the upstream drain pipe, and only the outlet 3 is fitted with a first reducing 45° elbow 32 to reduce its original diameter and change the direction of outflow, and then the downstream drain pipe is connected (Figure 7c).

[0044] Furthermore, in the case of an upstream drain pipe (not shown) and a downstream drain pipe (not shown) with the same layout as in Figure 7c, if the diameter of either drain pipe is smaller than the original diameter of the inlet 2 and the original diameter of the outlet 3, then a reducing socket 21 is attached to the inlet 2 to adjust (reduce the diameter) its original diameter to match the diameter of the upstream drain pipe, and the upstream drain pipe is connected. At the outlet 3, a second reducing 45° elbow 33 is attached to adjust (reduce the diameter) its original diameter to match the diameter of the downstream drain pipe, in other words, the diameter of the inlet 2 reduced by the reducing socket 21, and to change the direction of outflow, and the downstream drain pipe is connected (Figure 7d).

[0045] As can be understood by referring to Figures 7a to 7d, the backflow prevention joint 1 of this embodiment can be easily installed between upstream and downstream drain pipes that have a difference in height and various diameters and inclinations, by attaching a reducing socket 21 or the like that matches the diameter of the upstream drain pipe to the inlet 2 as needed, and reducing increases 30, 31 or reducing elbows 32, 33 or the like that that match the diameter and inclination of the downstream drain pipe to the outlet 3 as needed. In this embodiment, the combinations of reducing sockets 21, reducing increases 30, 31 and reducing 45° elbows 32, 33 shown in Figures 7a to 7d are merely examples, and any combination is possible depending on the diameter and inclination of the upstream and downstream drain pipes, and various adapters can be attached as needed.

[0046] The backflow suppression joint 1 of this embodiment includes a valve pipe 5 that communicates with the inlet 2 and protrudes downward from the inlet 2 so as to curve toward the interior of the body 4, penetrating the wall surface of the body 4 (Figures 7a to 7d). The valve pipe 5 does not necessarily have to protrude entirely toward the interior of the body 4 in the circumferential direction; for example, a part of the valve pipe 5, such as the upper half in the circumferential direction, may protrude toward the interior of the body 4. The protruding portion of the valve pipe 5 may be formed integrally with the body 4, or it may be configured as a separate part that can be separated from the body 4.

[0047] Furthermore, a valve seat portion 50 is formed at the open end of the valve pipe 5, which is inclined to approach the inlet 2 from top to bottom. The valve seat portion 50 functions in cooperation with the valve body 6, which will be described later, by contacting the valve body 6, in order to prevent backflow of wastewater.

[0048] In this embodiment, by providing the valve pipe 5, the wastewater that flows horizontally from the inlet 2 into the body 4 can be reliably and smoothly deflected downward. Furthermore, since the valve pipe 5 is cylindrical, if the opening surface cut off by a plane perpendicular to the pipe axis of the valve pipe 5 is made into the valve seat portion 50 at the opening end, the valve seat portion 50 is formed to be approximately circular, and the shape of the valve body 6 that abuts against the valve seat portion 50 can also be approximately circular, thus simplifying the design and molding process.

[0049] Furthermore, as described above, the valve seat portion 50 is inclined such that the protrusion decreases from the top to the bottom. Therefore, the valve body 6, which is suspended from the valve seat portion 50 so as to be able to open and close, forms a gap between itself and the valve seat portion 50 under normal conditions, thereby ensuring the smooth flow of forward-flowing wastewater. In the event of an abnormality (when backflow occurs), the pressure of the reverse-flowing wastewater causes the valve body 6 to come into contact with the valve seat portion 50, effectively suppressing the backflow of wastewater.

[0050] In this embodiment, the joint body 10 is integrally formed from a plastic material. There are no particular limitations on the material used for the joint body 10, and mainly known materials such as plastics can be used. From the viewpoint of having high strength, water resistance, and ease of molding, polyvinyl chloride resin is preferred.

[0051] <Lid> Figure 8 shows a perspective view from above of the cover 8 and valve body 6 of the backflow suppression joint 1 according to this embodiment, and Figure 9 shows a perspective view from below of the cover 8 and valve body 6 shown in Figure 8. Figure 10 shows a front view of the cover 8 and valve body 6 shown in Figures 8 and 9, Figure 11 shows a side view of the cover 8 and valve body 6 shown in Figures 8 and 9, and Figure 12 shows an exploded view of the cover 8 and valve body 6 shown in Figures 8 and 9.

[0052] As shown in Figures 7a-7d and 8-12, the lid 8 has a thick, roughly disc-shaped form, and the valve body 6 is pivotally supported on its lower surface via a suspension arm 82 extending downward. A pair of triangular handles 800 are formed on the upper surface of the lid 8 for gripping and rotating it. Both the lid 8 and the valve body 6 are made of polyvinyl chloride resin, but there are no particular limitations on the materials used; mainly known materials such as plastics can be used.

[0053] More specifically, as shown in Figure 12, the lid 8 consists of a lid body 80 having a handle 800 for opening and closing the inspection port 7, a cap portion 81 fitted to the lower part of the lid body 80, and a suspension arm 82 integrally molded with the cap portion 81 and extending downward from the lower surface of the cap portion 81. In other words, in this embodiment, the lid body 80 and the cap portion 81 are configured as separate and independent parts, and the lid body 80 and the cap portion 81 are rotatable relative to each other in the circumferential direction.

[0054] Furthermore, the upper surface of the cap portion 81 is provided with a pair of auxiliary handles 813 (Figure 12) to facilitate gripping the cap portion 81, and the lower surface of the cap portion 81 has a planar bulge 810 with a different inclination angle from the upper surface of the cap portion 81 to prevent the valve body 6 from unnecessarily rotating too far toward the inspection port 7, i.e., toward the side where the valve body 6 opens.

[0055] The shape and structure of the bulge portion 810 are not particularly limited as long as they can restrict the rotation of the valve body 6 within a certain range. In this embodiment, the bulge portion 810 is provided so as to occupy most of the internal space of the inspection opening 7, and its restricting surface 811 is inclined so as to approach the valve body 6 from bottom to top (Figures 7a to 7d). As a result, the backflow water rising upward from the outlet 3 collides with the restricting surface 811 of the bulge portion 810 and is converted into a flow that pushes the valve body 6 in a direction that closes it from the downstream side, thus making the closing action of the valve body 6 by the backflow water more reliable. Furthermore, when the bulge portion 810 is opened until it contacts the valve body 6, it forms a flow path that curves downward so as to be continuous with the ceiling portion of the valve pipe 5 inside the joint body 10. As a result, even if a large amount of wastewater flows horizontally from the inlet 2, the wastewater can be reliably and smoothly deflected downward.

[0056] Furthermore, in this embodiment, the lower surface of the cap portion 81 is provided with a convex second engaging portion 812 that can be fitted with a concave first engaging portion 71 provided on the inner circumferential surface of the inspection opening 7 described above, and is positioned opposite to it using the side surface of the bulging portion 810. The shape and structure of the second engaging portion 812 are not particularly limited as long as it can be fitted with the concave first engaging portion 71, and may be, for example, a projection that extends vertically on its own from the back surface of the cap portion 81.

[0057] In this embodiment, a groove 814 (Figure 12) is formed on the side surface (circumferential surface) of the cap portion 81, and a packing 83 made of elastomer material is fitted into the groove 814 to improve sealing with the inspection opening 7 (see Figures 7a to 7d). In this embodiment, the lid portion 8 is composed of a lid body 80 and a cap portion 81 with a suspension arm 82 as separate and independent parts, but these may be formed as a single integrated part.

[0058] In this embodiment, when closing the inspection opening 7 using the lid portion 8, first a pair of convex second engaging portions 812 provided on the cap portion 81 are fitted into a pair of concave first engaging portions 71 provided inside the inspection opening 7. The cap portion 81, which supports the valve body 6, is supported from below by the stepped portion 70 inside the inspection opening 7, and is fixed to the inspection opening 7 so as not to rotate in the circumferential direction by the engagement of the second engaging portions 812 and the first engaging portions 71.

[0059] Next, after setting the cap portion 81 inside the inspection port 7, the lid body 80 is placed on top of the cap portion 81 inside the inspection port 7. This ensures that the cap portion 81 is sandwiched between the lid body 80 and the stepped portion 70 of the inspection port 7 without any looseness or rotation. As a result, the valve body 6 supported by the cap portion 81 is precisely set in the predetermined position and can be precisely brought into contact with the valve seat portion 50 inside the joint body 10.

[0060] Furthermore, when removing the cover 8 to open the inspection port 7, the valve body 6 can be easily removed by removing the cover body 80 and cap portion 81 from the inspection port 7 using the reverse procedure described above. Also, if the cover body 80 and cap portion 81 are integrally formed, the valve body 6 can be removed together with the cover 8 when it is removed from the inspection port 7.

[0061] As shown in Figures 1-4, 6, 8, and 9, the backflow prevention joint 1 of this embodiment is equipped with a locking mechanism 9 to prevent the lid 8 from detaching from the inspection port 7 due to an increase in the pressure of water or air inside the joint 1. In this embodiment, the locking mechanism 9 uses a bayonet mechanism that prevents the lid 8 from detaching from the inspection port 7 by rotating the lid body 80 circumferentially relative to the inspection port 7. More specifically, the locking mechanism 9 consists of a pair of crank-shaped projections 90 provided at opposing positions 180° apart on the side surface (circumferential surface) of the lid body 80, and a pair of crank-shaped notches 91 provided at opposing positions 180° apart on the receiving end of the inspection port 7.

[0062] Therefore, when the lid 8 is set into the inspection port 7 with the cap portion 81 that supports the valve body 6, and the lid body 80 is fitted into the receiving port of the inspection port 7, it can be rotated to a position where the projection 90 and the notch 91 engage, thereby locking the cap portion 81 in a way that prevents it from being unintentionally detached from the inspection port 23 without rotating it. In the bayonet mechanism described above, the notch 91 does not necessarily have to be a crank-shaped projection, but may be a simple rod-shaped projection, for example. Also, the locking means 9 does not necessarily have to be a bayonet mechanism, and especially when the lid body 80 and the cap portion 81 are integrally formed, known engaging means such as a hook that locks the lid 8 from above can also be used.

[0063] <valve body> As shown in Figures 7a-7d and 8-12, in this embodiment, the valve body 6 has a circular shape so that it can contact the circular valve seat portion 50 in a liquid-tight manner when viewed from the front (Figure 10), and in a side view, it has a recess 60 that is recessed from the downstream side to the upstream side so that it receives a large force (resistance) from reverse flow drainage and a small force (resistance) from forward flow drainage (Figures 8 and 11).

[0064] The valve body 6 is supported in a rotatable manner so as to be able to open and close relative to the valve seat portion 50, but there are no particular limitations on the support position or support method, and it may be supported by, for example, the inner wall of the joint body 10, the valve tube 5, or the cover portion 8.

[0065] In this embodiment, the valve body 6 has a horizontally oriented L-shaped support arm 61 on its upper part, and is pivotally supported on the suspension arm 82 of the cover 8 via the support arm 61, either by a pin or directly. Furthermore, when the cover 8 is set in a predetermined position inside the inspection opening 7, the valve body 6 is pivotally supported above the valve pipe 5 and at a position (fulcrum p) offset towards the inlet 2 side from the open end of the valve pipe 5 (valve seat 50), so that it can open and close relative to the valve seat 50. It is preferable that the shaft hole of the valve body 6 be formed to be slightly larger than the shaft diameter of the pin so that the valve body 6 can rotate smoothly, and in order to improve the sealing performance with the valve seat 50, it may be made into an elongated hole shape so that there is no play between the pin and the valve body 6 when the valve body 6 abuts against the valve seat 50.

[0066] Therefore, when the valve body 6 is suspended, it is positioned at an angle so that it approaches the inlet 2 from top to bottom, as shown in Figures 7a to 7d. When the valve body 6 is positioned at an angle as described above, the backflow water rising upward from the outlet 3 will collide with the recessed downstream surface of the valve body 6 rather than the upstream surface, thus making the action of closing the valve body 6 with the backflow water more reliable.

[0067] Furthermore, as described above, by positioning the pivot point p of the valve body 6 at a location offset towards the inlet 2 side from the valve seat portion 50, the trajectory of the lower end of the valve body 6, that is, the trajectory of the part of the valve body 6 furthest from the pivot point p, approaches the inlet 2 and the valve seat portion 50. As a result, without changing the opening and closing angle of the valve body 6, the range of motion of the valve body 6 in the outlet region of the valve pipe 5 can be substantially narrowed, and the backflow suppression joint 1 can be made more compact.

[0068] More specifically, as shown in Figure 7a, the valve body 6 is preferably pivotally supported at a pivot point p that is offset such that L / D is preferably 0.15 to 0.45, more preferably 0.20 to 0.40, when D (mm) is the outer diameter of the open end (valve seat portion 50) of the valve pipe 5 and L (mm) is the distance from the open end face of the valve pipe 5 to the pivot point p of the valve body 6. In this case, the center of gravity of the valve body 6 will be located downstream of the contact surface that contacts the valve seat portion 50 of the valve body 6 when the valve body 6 is suspended.

[0069] If L / D is set to less than 0.15, the valve body 6 cannot be tilted sufficiently so that the backflow water rising upward from the outlet 3 first hits the downstream surface of the valve body 6. This makes the valve body 6 more likely to move in the opening direction, and it becomes impossible to adequately block the flow of backflow water. Furthermore, it becomes impossible to narrow the range of motion of the valve body 6 in the outlet region of the valve pipe 5 to the extent that it contributes to the compactness of the backflow suppression joint 1. On the other hand, if L / D is set to more than 0.45, it becomes necessary to secure space for the movement of the support arm 61 of the elongated valve body 6, which leads to the disadvantage of the joint body 10 becoming unnecessarily large.

[0070] In addition, in the backflow suppression joint 1 of this embodiment, a stopper (not shown) may be provided at the pivot point p of the valve body 6 to prevent the valve body 6 from rotating unnecessarily too far toward the inspection port 7, i.e., toward the opening side. If a stopper is provided at the pivot point p of the valve body 6 as described above, the bulge 810 provided on the lower surface of the cover 8 for the same purpose can be omitted.

[0071] Furthermore, in the backflow suppression joint 1 of this embodiment, a buoyancy generating part (not shown) having a specific gravity less than that of water may be provided upstream of the valve body 6 and on the inlet 2 side of the vertical plane passing through the fulcrum p of the valve body 6. By positioning the buoyancy generating part eccentrically upstream of the valve body 6 in this way, when backflow occurs, the buoyancy generating part is pulled up in the direction of closing the valve body 6 by the backflow rising upward from the outlet 3, thereby more reliably preventing malfunction of the valve body 6. [Explanation of Symbols]

[0072] 1. Backflow prevention joint 10. Fitting body 2...Inlet 20····Sort opening step section 21.. Reducing socket 3... Outlet 30.....First Diameter Increaser 31..Second reducing increaser 32.....First reducing 45° elbow 33...Second reducing 45° elbow 4. Torso 5. Valve tube 50... Valve seat 6. Valve body 60····recess 61. Support arm 7...Inspection hatch 70... Step section 71...First engagement part 8...Lid part 80····Lid body 800...handle 81... Cap part 810...bulge 811...Regulations 812...Second engaging part 813...Auxiliary handle 814... Groove 82.. Suspension arm 83...Gasket 9. Locking mechanism 90...Protrusion 91...Notch a·····First central axis b....Second central axis c·····Third central axis p...Fulcrum D·····Outer diameter of the opening end (valve seat) (mm) L·····Distance from the opening end face to the pivot point of the valve body (mm)

Claims

1. An inlet having a first central axis extending horizontally, An outlet having a second central axis extending vertically, A body portion connecting the inlet and the outlet, A valve seat portion formed inside the body portion, A valve body supported so as to be able to open and close relative to the valve seat portion, An inspection port having a third central axis that extends from the body and extends upward diagonally away from the inlet, A lid that can be detachably attached to the inspection opening and Equipped with, and The valve body is a backflow suppression joint that is rotatably supported on the cover.

2. The backflow suppression joint according to claim 1, characterized in that the diameter of the inspection port is the same as the diameter of the outlet.

3. The backflow suppression joint according to claim 2, characterized in that the diameter of the outlet is larger than the diameter of the inlet.

4. The lid portion includes a cap portion that is attached to the inspection opening so as not to rotate in the circumferential direction, It consists of a lid body which is mounted on the cap portion so as to be rotatable in the circumferential direction relative to the inspection opening, and The backflow suppression joint according to claim 1, characterized in that the valve body is supported by the cap portion.

5. The inner circumferential surface of the inspection opening is provided with a first engaging portion that fixes the cap portion to the inspection opening so that it cannot rotate in the circumferential direction, and The backflow suppression joint according to claim 4, characterized in that the cap portion is provided with a second engaging portion that engages with the first engaging portion.

6. The backflow suppression joint according to claim 5, further comprising a locking mechanism to prevent the lid from detaching from the inspection port due to an increase in the pressure of water or air inside the body.

7. The backflow suppression joint according to claim 6, characterized in that the locking means is a bayonet mechanism which engages the lid with the inspection opening by rotating the lid circumferentially with respect to the inspection opening.

8. A valve tube is provided in the body portion so as to communicate with the inlet portion and protrude into the interior of the body portion, The backflow suppression joint according to any one of claims 1 to 3, characterized in that the valve seat portion is formed at the open end of the valve pipe.

9. The backflow suppression joint according to claim 8, characterized in that the open end is inclined to approach the inlet from the top to the bottom.

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