Backflow prevention joint and backflow prevention system equipped with the same

Abstract

To provide backflow prevention means capable of smoothly flowing forward flow drain under normal conditions and surely preventing the flow of backflow water when a backflow occurs.MEANS FOR SOLVING THE PROBLEM: A backflow prevention joint comprises a valve pipe having an inlet opening and an outlet opening, a valve body having a buoyancy generating portion and a valve body side hinge portion rotatably supported by a first hinge support portion provided near the outlet opening of the valve pipe, and a floater having a floater side hinge portion rotatably supported by a second hinge support portion provided near the outlet opening of the valve pipe. One or more valve body side engaging teeth are provided on the outer periphery of the valve body side hinge portion. One or more floater side engaging teeth are provided on the outer periphery of the floater side hinge portion. When a downward force is generated on the floater, the downward force causes the floater side engaging teeth to press the valve body side engaging teeth in the direction in which the valve body opens the outlet opening.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a backflow prevention fitting and a backflow prevention system equipped with said fitting, and in particular to a backflow prevention fitting characterized in that the downward force generated in the floater due to its own weight keeps the valve body in an open position, and a backflow prevention system equipped with said fitting in a bottomed catch basin. [Background technology]

[0002] Generally, wastewater discharged from drainage facilities such as toilets in houses is collected in drainage manholes installed within residential areas via drainage pipes connected to each drainage facility in order to mitigate sudden changes in the amount of wastewater or to allow for the removal and inspection of foreign objects such as garbage. The wastewater collected in the drainage manholes then flows out into the main sewer pipe via a public manhole or manhole.

[0003] However, when a large amount of rainwater flows into the sewer main in a short period of time, the drainage capacity of the sewer main is exceeded and the overflowing wastewater flows back through catch basins, etc., causing the problem of the backflowing wastewater spouting out from the indoor drainage equipment connected to the drainage pipe. On the other hand, even if the amount of forward flow wastewater is small under normal circumstances, there is also the issue of having to smoothly flow it downstream without clogging the wastewater with foreign objects such as filth contained in it.

[0004] Therefore, in order to prevent wastewater backflowing from the main sewer pipe from overflowing from indoor drainage equipment through drainage manholes, etc., and to prevent clogging due to foreign matter contained in the wastewater even when the amount of forward flow wastewater is small, a backflow prevention device has been developed in which the outlet opening against which the valve body abuts is tilted so that it retreats as it moves from top to bottom, as described in Patent Publication No. 2020-153508 (Patent Document 1), usually forming a gap between the valve body and the outlet opening to secure a flow path.

[0005] Furthermore, in the backflow prevention device described in Patent Document 1, the valve element is normally always in an open state, so when a backflow occurs, it may be unstable as to whether the valve element reliably closes the outlet opening. Therefore, even in backflow prevention devices in which the outlet opening is tilted backward like in Patent Document 1, in order to make the closing action of the valve element more reliable when a backflow occurs, backflow prevention devices have been developed in which a float is attached to the cover (valve element), as described in, for example, JP-A-10-18405 (Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-153508 A [Patent Document 2] Japanese Patent Application Publication No. 10-18405 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in backflow prevention devices such as those described in Patent Documents 1 and 2, the outlet opening is inclined so that it is recessed, and the valve body, which is normally suspended by its own weight, is kept with the outlet opening open. Therefore, when backflow occurs, the backflowing water may flow around to the upstream back surface of the valve body (the gap between the valve body and the outlet opening) before it reaches the downstream surface of the valve body, making it difficult for the valve body to close the outlet opening, and there may be cases where the backflow of wastewater cannot be prevented.

[0008] Therefore, the present invention aims to provide a backflow prevention means that can smoothly drain water even when the amount of forward flow drainage is small under normal conditions, and yet can reliably prevent the flow of backflow water when backflow occurs. [Means for solving the problem]

[0009] After extensive research into the structure of the backflow prevention means and the flow of wastewater, the inventors discovered that by inclining the outlet opening of the backflow prevention means so that it progresses from upstream to downstream as it moves vertically or from top to bottom, the blocking properties of the valve body when backflow occurs can be increased, and that for forward flow wastewater, a smooth flow can be ensured by linking the opening of the valve body under normal conditions to the movement of the floater which descends under its own weight, thus completing the present invention.

[0010] That is, according to the present invention, a backflow prevention joint is provided which comprises a valve pipe having an inlet opening and an outlet opening, a valve body having a buoyancy generating portion and a valve body side hinge portion rotatably supported by a first hinge support portion provided near the outlet opening of the valve pipe, and a floater having a floater side hinge portion rotatably supported by a second hinge support portion provided near the outlet opening of the valve pipe, wherein one or more valve body side engaging teeth are provided on the outer periphery of the valve body side hinge portion and one or more floater side engaging teeth are provided on the outer periphery of the floater side hinge portion, and when a downward force is generated on the floater, the downward force causes the floater side engaging teeth to press the valve body side engaging teeth in the direction in which the valve body opens the outlet opening, in other words, the floater side engaging teeth engage with the valve body side engaging teeth, causing the valve body to rotate in the direction in which the outlet opening is opened.

[0011] According to the present invention, the outlet opening of the valve pipe is inclined so as to advance from the upstream side to the downstream side as it goes vertically or from top to bottom, so that the blocking ability of the valve body when backflow occurs is improved and the flow of backflow water can be reliably suppressed. Also, one or more engagement teeth are provided on the outer periphery of the hinge part on the valve body side and the outer periphery of the hinge part on the floater side, and when a downward force is generated on the floater due to its own weight, the floater side engagement tooth presses the valve body side engagement tooth in the direction in which the valve body opens the outlet opening due to the downward force, so that under normal circumstances, the valve body keeps the outlet opening open, and even if the forward flow drainage is small, a smooth flow of forward flow drainage is guaranteed, and clogging does not occur due to foreign matter contained in the drainage.

[0012] In the backflow prevention joint of the present invention, the range of rotation of the valve body in the opening direction may be configured to be restricted by the valve body abutting against a float, or a stopper may be provided on the first hinge support portion of the valve pipe, and the range of rotation of the valve body in the opening direction may be restricted by the valve body side engaging teeth engaging with the stopper.

[0013] In a backflow prevention joint, if the rotation range of the valve body toward the opening side becomes too large, backflow water may collide with the upstream back surface of the valve body when a backflow occurs, and the valve body may not be able to operate to close the outlet opening. Therefore, in the present invention, a floater or a dedicated stopper is made to function as a stopper that restricts the rotation range of the valve body, so that backflow water is sure to collide with the downstream surface of the valve body, and the valve body is sure to rotate to the side that closes the outlet opening without malfunctioning due to backflow water.

[0014] The backflow prevention fitting of the present invention may be configured so that when an upward force is generated on the floater, the floater side engagement teeth do not press the valve body side engagement teeth in the direction in which the valve body closes the outlet opening due to the upward force, in other words, the engagement between the floater side engagement teeth and the valve body side engagement teeth is released.

[0015] In other words, the backflow prevention joint of the present invention is a backflow prevention joint comprising a valve pipe having an inlet opening and an outlet opening, a valve body rotatably supported near the outlet opening of the valve pipe, a floater having a buoyancy generating portion and rotatably supported near the outlet opening of the valve pipe, and connecting means for linking or unlinking the operation of the valve body and the operation of the floater, in which the valve body and the floater can be configured so that the connecting means connects them so that the downward movement of the floater rotates the valve body in a direction opening it, and the valve body and the floater are unconnected so that the upward movement of the floater does not rotate the valve body in a direction closing it.

[0016] When the above-mentioned configuration is adopted in the present invention, when a downward force is generated on the floater due to its own weight, the valve disc receives a force from the floater to rotate in a direction to open the outlet opening via the floater side engagement teeth and the valve disc side engagement teeth, but when an upward force is generated on the floater due to buoyancy, the floater side engagement teeth and the valve disc side engagement teeth are disengaged, and the valve disc is essentially in a free state without receiving any force from the floater. Therefore, when the downstream surface of the valve disc receives pressure from the backflowing water, the valve disc naturally and smoothly rotates in a direction to close the outlet opening.

[0017] Furthermore, the backflow prevention joint of the present invention can be configured so that when an upward force is generated in the floater, the floater side engagement teeth press the valve body side engagement teeth in the direction in which the valve body closes the outlet opening due to the upward force, in other words, the floater side engagement teeth engage with the valve body side engagement teeth to rotate the valve body in the direction in which the outlet opening is closed. In other words, the opening and closing action of the valve body may be configured to be linked to the movement of the floater, whether the floater descends due to its own weight or ascends due to buoyancy.

[0018] In this case, the valve body will not be fully closed unless the liquid level of the backflow water reaches a predetermined set level, but when the liquid level of the backflow water reaches or exceeds the set level, the valve body can reliably block the outlet opening without malfunctioning and maintain that state.

[0019] The backflow prevention joint of the present invention may also be attached as a backflow prevention system to the inlet of a bottomed catch basin that has an inlet that opens horizontally, an outlet that communicates with the inlet and also opens horizontally, and an inspection hatch that communicates with the inlet and the outlet and also opens upward. Note that in this specification, "upward" means "upward" facing approximately vertically, and does not mean "vertically upward" facing vertically in the strict sense. Effect of the Invention

[0020] According to the backflow prevention joint of the present invention, the outlet opening of the valve pipe is inclined so as to advance from the upstream side to the downstream side as it goes vertically or from top to bottom, so that the blocking ability of the valve body when backflow occurs is enhanced and the flow of backflow water can be reliably prevented. In addition, one or more engagement teeth are provided on the outer periphery of the hinge part on the valve body side and the outer periphery of the hinge part on the floater side, and when a downward force is generated on the floater due to its own weight, the floater side engagement tooth presses the valve body side engagement tooth in the direction in which the valve body opens the outlet opening due to the downward force, so that under normal circumstances, the valve body keeps the outlet opening open, and even if the forward flow drainage is small, a smooth flow of forward flow drainage is guaranteed, and clogging does not occur due to foreign matter contained in the drainage.

[0021] According to the backflow prevention fitting of the present invention, when an upward force is generated on the floater, the upward force causes the floater side engagement teeth to disengage from the valve body side engagement teeth so that the valve body does not press the floater side engagement teeth in the direction of closing the outlet opening, and the valve body will naturally and smoothly rotate in the direction of closing the outlet opening as the downstream surface receives pressure from the backflow water.

[0022] In addition, according to the backflow prevention fitting of the present invention, when an upward force is generated on the floater, the upward force causes the floater side engaging teeth to press the valve body side engaging teeth in the direction in which the valve body closes the outlet opening; in other words, the floater side engaging teeth engage with the valve body side engaging teeth to rotate the valve body in the direction in which the outlet opening is closed.In this case, when the liquid level of the backflow water reaches a set level or above, the valve body will reliably block the outlet opening without malfunction, and will be able to maintain that state. [Brief description of the drawings]

[0023] [Figure 1] 1 is a perspective view showing an overall outline of a backflow prevention joint according to one embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view taken along line AA of the backflow prevention joint shown in FIG. 1. [Diagram 3] 2 is a perspective view showing a valve body of the backflow prevention joint shown in FIG. 1. [Figure 4] 2 is a perspective view showing a floater of the backflow prevention joint shown in FIG. 1. [Diagram 5] 2 is a perspective view showing a valve pipe of the check joint shown in FIG. 1. [Figure 6] 2 is a partial cross-sectional view showing a schematic diagram of the movement of a valve body and a floater of the backflow prevention joint shown in FIG. 1. [Figure 7] 1 is a perspective view showing an overall outline of a backflow prevention system (partially transparent) according to one embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view of the backflow prevention system shown in FIG. 7 taken along line BB. [Figure 9] FIG. 11 is a perspective view showing an overall outline of a backflow prevention joint according to another embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view taken along line CC of the backflow prevention joint shown in FIG. 9. [Figure 11] 10 is a perspective view showing a valve body of the backflow prevention joint shown in FIG. 9. [Figure 12] 10 is a perspective view showing a floater of the backflow prevention joint shown in FIG. 9. [Figure 13] 10 is a perspective view showing a valve pipe of the check joint shown in FIG. 9. FIG. [Figure 14] 10 is a partial cross-sectional view showing a schematic diagram of the movement of the valve body and the floater of the backflow prevention joint shown in FIG. 9. [Figure 15] FIG. 2 is a perspective view showing an overall outline of a backflow prevention system (partially transparent) according to another embodiment of the present invention. [Figure 16] FIG. 16 is a DD cross-sectional view of the backflow prevention system shown in FIG. 15. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, a backflow prevention joint 1, 1a according to one embodiment of the present invention and a backflow prevention system 2, 2a to which the joint 1, 1a is attached will be described in detail with reference to the drawings. Note that the present invention is not limited to the following examples, and various modifications are possible within the scope of the technical concept of the present invention. EXAMPLES

[0025] 1. First embodiment <Backflow prevention joint> Fig. 1 shows a perspective view illustrating the overall outline of a backflow prevention joint 1 according to a first embodiment of the present invention, and Fig. 2 shows a cross-sectional view taken along line AA of the backflow prevention joint 1 shown in Fig. 1. Of the backflow prevention joint 1 shown in Fig. 1, Fig. 3 shows a perspective view illustrating a valve body 3, Fig. 4 shows a perspective view illustrating a floater 4, and Fig. 5 shows a perspective view illustrating a valve pipe 5.

[0026] 1 and 2, the backflow prevention joint 1 of the first embodiment comprises a cylindrical valve pipe 5 (FIG. 5) having an inlet opening 50 and an outlet opening 51, a valve element 3 (FIG. 3) rotatably supported near the outlet opening 51 of the valve pipe 5, and a floater 4 (FIG. 4) having a buoyancy generating part 40 and rotatably supported on the valve pipe 5 in the same manner as the valve element 3. In the first embodiment, the floater 4 is configured separately and independently from the valve element 3 so that gravity generated in the floater 4 and buoyancy generated in the buoyancy generating part 40 can function efficiently, and the buoyancy generating part 40 of the floater 4 is arranged so that it can rotate away from the valve element 3 in a region downstream of the valve element 3 and / or a region above the valve element 3.

[0027] Furthermore, in the first embodiment, the backflow prevention joint 1 is made of polyvinyl chloride resin, but there are no particular limitations on the material used, and known materials such as plastics can be used.

[0028] <Valve body> The backflow prevention joint 1 of the first embodiment includes a valve body 3 for opening and closing a valve seat 52 formed at an outlet opening 51 of a valve pipe 5 described later. The valve body 3 is not particularly limited in shape as long as it can abut against and close the valve seat 52, and in the first embodiment, the downstream surface 33 of the valve body 3 has a shape that is concave from the downstream side to the upstream side (the upstream back surface 34 has a shape that bulges from the downstream side to the upstream side) (FIG. 2).

[0029] In this case, the valve body 3 does not receive a large force even when the wastewater collides with the upstream back surface 34 that bulges toward the upstream side, but receives a large force when the wastewater collides with the downstream surface 33 that is recessed toward the upstream side. Therefore, when backflow occurs, the backflow water mainly collides with the downstream surface 33 of the valve body 3, so that the valve body 3 receives a large force and operates to close the outlet opening 51, and can reliably prevent the backflow of wastewater. In the first embodiment, a groove is provided on the peripheral portion of the valve body 3 at a position where it abuts against the valve seat portion 52, and a packing 30 made of an elastic material such as rubber is fitted into the groove to improve the sealing performance with the outlet opening 51.

[0030] A valve body side hinge portion 31 extending in the radial direction is formed on the upper peripheral edge portion of the valve body 3, and one valve body side engagement tooth 32 protruding in the radial direction from the outer peripheral surface is formed on the outer periphery of the rotation axis O of the valve body side hinge portion 31. The shape and number of the valve body side engagement tooth 32 are not particularly limited, but in the first embodiment, the valve body side engagement tooth 32 is a convex portion having a smooth triangular cross section, and may be formed from a convex portion and / or a concave portion so as to form one tooth of a gear. In addition, the valve body side engagement tooth 32 may be one or two or more, as long as the number is such that the valve body side engagement tooth 32 can engage with the floater side engagement tooth 42 at least when the floater 4 descends.

[0031] <Floater> The backflow prevention joint 1 of the first embodiment is equipped with a floater 4 to assist the movement of the valve body 3. The floater 4 has a buoyancy generating part 40, and is not particularly limited as long as the floater 4 generates a force to rotate the valve body 3 in the opening direction due to its own weight, and the shape, structure, and material are capable of generating buoyancy against the weight of the floater 4 in water. In the first embodiment, the buoyancy generating part 40 is set so that the rotational moment generated by the weight of the floater 4 at the rotation axis P of the floater 4 is larger than the rotational moment generated by the weight of the valve body 3 at the rotation axis O of the valve body 3, and the rotational moment generated by the buoyancy of the buoyancy generating part 40 at the rotation axis P of the floater 4 is set so that it is larger than the rotational moment generated by the weight of the floater 4.

[0032] 2, in the first embodiment, the buoyancy generating part 40 of the floater 4 is formed as a hollow plastic structure having a thick disk shape because it is strong and easy to manufacture. The buoyancy generating part 40 is composed of a disk-shaped dish part 43 and a disk-shaped cap part 44, and is formed so that a cavity is maintained inside by joining the peripheral part of the dish part 43 and the peripheral part of the cap part 44 liquid-tightly.

[0033] A floater side hinge part 41 extending in the radial direction is formed on the upper peripheral edge part of the plate part 43 of the floater 4, and one floater side engagement tooth 42 protruding in the radial direction from the outer peripheral surface is formed on the outer periphery of the rotation axis P of the floater side hinge part 41. The shape and number of the floater side engagement tooth 42 are not particularly limited, but in the first embodiment, the floater side engagement tooth 42 is a convex part having a smooth triangular cross section like the valve body side engagement tooth 32, and may be formed from a convex part and / or a concave part so as to form one tooth of a gear. In addition, the floater side engagement tooth 42 may be one or two or more, as long as the number is such that it can engage with the valve body side engagement tooth 32 at least when the floater 4 descends.

[0034] As shown in Figs. 1 and 4, in the first embodiment, the floater side hinge portion 41 has a first protrusion 410 and a second protrusion 411 protruding in a rectangular parallelepiped shape from its side surface. The first protrusion 410 abuts against the hinge support portion 51 of the valve tube 5 when the floater 4 rotates upward, thereby functioning as a stopper that restricts the rotation range of the floater 4 on the ascending side, and the second protrusion 411 abuts against the hinge support portion 51 of the valve tube 5 when the floater 4 rotates downward, thereby functioning as a stopper that restricts the rotation range of the floater 4 on the descending side. In the first embodiment, the rotation range of the floater 4 on the ascending side can also be restricted by abutting against the valve body 3, so that the use of the valve body 3 can be given priority for restriction, or the use of the first protrusion 410 can be given priority for restriction, or both can be arranged to function simultaneously for restriction.

[0035] <Valve pipe> 5, the valve pipe 5 has a substantially circular inlet opening 50 for attachment to an inlet of a catch basin or the like or an outlet of a pipe (neither of which are shown), and a substantially circular outlet opening 51 that communicates with the inlet opening 50 and forms a valve seat 52 that abuts against the valve body 3. A groove is provided in the circumferential direction on the outer periphery of the valve pipe 5, and a packing 53 made of an elastic material such as rubber is fitted into the groove to improve the sealing performance with the inlet of a catch basin or the outlet of a pipe to which the backflow prevention joint 1 is attached.

[0036] In the first embodiment, the valve pipe 5 is a short straight pipe with a circular cross section, but it does not necessarily have to be entirely straight and may include a curved pipe section. The valve pipe 5 does not necessarily have to have a uniform diameter either, and may be configured as a differential diameter pipe joint in which the inlet opening 50 and the outlet opening 51 have different diameters, for example.

[0037] In the first embodiment, the outlet opening 51 (valve seat portion 52) of the valve pipe 5 is formed in a vertical direction (FIG. 2), but it may be formed to be inclined so as to progress from the upstream side to the downstream side as it goes from top to bottom (not shown). If the outlet opening 51 (valve seat portion 52) of the valve pipe 5 is shaped as described above, when the movement of the valve body 3 is not linked to the movement of the floater 4, the valve body 3 can close the outlet opening 51 (valve seat portion 52) only by its own weight, and the ability of the valve body 3 to close the outlet opening 51 is enhanced.

[0038] In addition, in the first embodiment, under normal circumstances, the movement of the valve body 3 is linked to the movement of the floater 4 which attempts to descend under its own weight, and the weight of the floater 4 causes the valve body 3 to keep the outlet opening 51 (valve seat portion 52) open, thereby ensuring a smooth flow of forward flow drainage even when the amount of forward flow drainage is small, and no clogging occurs due to foreign matter contained in the drainage.

[0039] 1, 2 and 5, a hinge support part 54 is provided on the upper part of the valve pipe 5 for rotatably supporting the valve body side hinge part 31 of the valve body 3 and the floater side hinge part 41 of the floater 4. The shape and number of the hinge support parts 54 are not particularly limited, and the hinge support parts 54 may be divided into a first hinge support part for supporting the valve body side hinge part 31 and a second hinge support part for supporting the floater side hinge part 41.

[0040] In the first embodiment, the hinge support part 54 is disposed on the side of the valve body side hinge part 31 so that the axial hole of the hinge support part 54 aligns with the axial hole of the valve body side hinge part 31, and the valve body 3 is rotatably supported by inserting one pin O through each axial hole. The hinge support part 54 is disposed on the side of the floater side hinge part 41 above the valve body side hinge part 31 so that the axial hole of the hinge support part 54 aligns with the axial hole of the floater side hinge part 41, and the floater 4 is rotatably supported by inserting one pin P through each axial hole. Furthermore, a partition-shaped insertion stopper 55 is provided on the upper part of the valve pipe 5 and upstream of the hinge support part 54 to prevent excessive insertion when attaching the inlet opening 50 of the valve pipe 5 to an inlet of a drainage basin or the like or an outlet of a piping.

[0041] The configuration of the valve body side hinge portion 31, the floater side hinge portion 41 and the hinge support portion 54 may be such that a pair of hinge support portions 54 are provided on the valve tube 5 so as to sandwich one valve body side hinge portion 31 or one floater side hinge portion 41 from both sides, as in the first embodiment, or, although not shown, a pair of valve body side hinge portions or a pair of floater side hinge portions may be provided on the valve body or the floater so as to sandwich one hinge support portion of the valve tube from both sides.In order to distribute the force applied to the pin as evenly as possible, it is preferable to have at least two or more of either the valve body side and floater side hinge portions, or the hinge support portions.

[0042] <Valve and floater movement> Fig. 6 shows a partial cross-sectional view that shows the movement of the valve body 3 and the floater 4 of the backflow prevention joint 1 according to the first embodiment. In Fig. 6, (a) shows the state of the valve body 3 and the floater 4 when basically no backflow water is occurring, (b) shows the state when the backflow water raises the floater 4 and the valve body 3 closes the outlet opening 51, and (c) shows the state when the backflow water increases even after the valve body 3 closes the outlet opening 51 and the floater 4 rises to its upper limit. The movement of the valve body 3 and the floater 4 will be explained below in the order of (a), (b), and (c) of Fig. 6.

[0043] <Aspects of (a)> 6(a) shows a normal state in which no backflow water is generated in a catch basin or the like to which the backflow prevention joint 1 according to the first embodiment is attached, and only forward flow drainage flows. In this case, no buoyancy is generated in the buoyancy generating part 40, and the rotational moment generated in the floater side hinge part 41 due to the weight of the floater 4 is larger than the rotational moment generated in the valve body side hinge part 31 due to the weight of the valve body 3. Therefore, a downward force is generated in the floater 4, and the floater side engagement teeth 42 press the valve body side engagement teeth 32 in the direction in which the valve body 3 opens the outlet opening 51, so that the valve body 3 maintains the outlet opening 51 of the valve pipe 5 in an open state. In other words, the downward movement of the floater 4 connects and links the floater side engagement teeth 42 with the valve body side engagement teeth 32, and rotates the valve body 3 in the opening direction.

[0044] In the embodiment shown in Fig. 6(a), when backflow water or the like occurs and an upward force is generated on the floater 4 due to the buoyancy generated in the buoyancy generating portion 40, the upward force rotates the floater side engagement teeth 42 away from the valve body side engagement teeth 32, so the valve body side engagement teeth 32 are not pressed in the direction in which the valve body 3 closes. In other words, the upward movement of the floater 4 causes the floater side engagement teeth 42 to be in a state of being uncoupled and unlinked from the valve body side engagement teeth 32, and does not rotate the valve body 3 in the closing direction. However, even if the movement of the valve body 3 is in a state of being uncoupled and unlinked from the movement of the floater 4, the valve body 3 itself naturally rotates in the closing direction due to its own weight, so that the valve body side engagement teeth 32 may maintain a state of abutment so as to follow the floater side engagement teeth 42 until the valve body 3 appears to close the outlet opening 51 (the embodiment in Fig. 6(b) described later).

[0045] In this way, in the embodiment shown in Figure 6(a), one or more valve body side engagement teeth 32 are provided on the outer periphery of the valve body side hinge portion 31, and one or more floater side engagement teeth 42 are provided on the outer periphery of the floater side hinge portion 41, and when a downward force is generated on the floater 4 due to its own weight, the floater side engagement tooth 42 presses the valve body side engagement tooth 32 in the direction in which the valve body 3 opens the outlet opening 51, so that under normal circumstances, the valve body 3 keeps the outlet opening 51 open, ensuring a smooth flow of forward flow drainage even when the amount of forward flow drainage is small, and no clogging occurs due to foreign matter contained in the drainage.

[0046] In the backflow prevention joint 1, if the rotation range of the valve element 3 in the opening direction becomes too large, backflow water may collide with the upstream back surface 34 of the valve element 3 when a backflow occurs, and the valve element 3 may not operate in the closing direction. Therefore, in the first embodiment, when the floater 4 rises, the valve element 3, which rotates in the direction to open the outlet opening 51 in conjunction with the floater 4's movement, comes into contact with the floater 4, thereby restricting the rotation range of the valve element 3 in the opening direction. In addition, although not shown, the rotation range of the valve element 3 in the opening direction may be restricted by providing a stopper on the hinge support part 54 that supports the valve element side hinge part 31 and engaging the valve element side engagement tooth 32 with the stopper.

[0047] In this way, in the backflow prevention fitting 1 of the first embodiment, the floater 4 or a dedicated stopper functions as a stopper that restricts the rotation range of the valve body 3, ensuring that backflow water collides with the downstream surface 33 of the valve body 3, and ensuring that the valve body 3 rotates to the closing side without malfunctioning due to backflow water.

[0048] <Aspects of (b)> FIG. 6(b) shows a state in which backflow water (not shown) occurs in a catch basin or the like to which the backflow prevention joint 1 according to the first embodiment is attached, and the backflow water raises the floater 4, causing the valve body 3 to close the outlet opening 51. In this case, buoyancy is generated in the buoyancy generating part 40 by the backflow water, and the rotational moment generated in the floater side hinge part 41 by the buoyancy of the buoyancy generating part 40 is greater than the rotational moment generated in the floater side hinge part 41 by the floater 4's own weight. Therefore, a total upward force is generated in the floater 4, and at that time, the floater side engagement teeth 42 rotate so as to move away from the valve body side engagement teeth 32 due to the upward force, so that the valve body side engagement teeth 32 are not pressed in the direction in which the valve body 3 closes. In other words, the upward movement of the floater 4 causes the floater side engagement teeth 42 to be uncoupled and unlinked from the valve body side engagement teeth 32, and does not rotate the valve body 3 in the closing direction. However, as shown in Figure 6(b), even if the movement of the valve body 3 is unconnected and unlinked with the movement of the floater 4, the valve body side engagement teeth 32 may appear to remain in contact with the floater side engagement teeth 42.

[0049] 6(b), one or more valve body side engagement teeth 32 are provided on the outer periphery of the valve body side hinge part 31, one or more floater side engagement teeth 42 are provided on the outer periphery of the floater side hinge part 41, and when an upward force is generated in the floater 4, the upward force does not cause the floater side engagement teeth 42 to press the valve body side engagement teeth 32 in the direction of closing the valve body 3. Therefore, the valve body 3 is in a state of being suspended so as to be free to swing, and naturally rotates in the direction of closing the outlet opening 51 due to its own weight, so that the backflow water collides with the downstream side surface 33 of the valve body 3 before the upstream side back surface 34, and the valve body 3, which receives pressure from the downstream side surface 33 by the backflow water, naturally and smoothly rotates in the direction of closing the outlet opening 51.

[0050] <Aspects of (c)> Figure 6(c) shows a state in which, in a catch basin or the like to which the backflow prevention fitting 1 of the first embodiment is attached, the amount of backflow water increases even after the valve body 3 closes the outlet opening 51 (the state of Figure 6(b)), and the rise of the floater 4 reaches its upper limit. In this case, as in the state of Figure 6(b), an upward force is generated in the floater 4 due to the buoyancy of the buoyancy generating part 40, and at that time, the floater side engagement teeth 42 rotate away from the valve body side engagement teeth 32 due to this upward force, so that the valve body side engagement teeth 32 are not pressed in the direction in which the valve body 3 closes. In other words, even in the state of Figure 6(c), the upward movement of the floater 4 causes the floater side engagement teeth 42 to be uncoupled and unlinked from the valve body side engagement teeth 32, and does not rotate the valve body 3 in the closing direction. With the valve body 3 keeping the outlet opening 51 closed, the floater 4 rises independently of the valve body 3 from the position shown by the thin imaginary line to the position shown by the solid line where the floater 4 reaches the upper limit of its rotation range.

[0051] In this manner, in the embodiment shown in Fig. 6(c), one or more valve body side engagement teeth 32 are provided on the outer periphery of the valve body side hinge part 31, and one or more floater side engagement teeth 42 are provided on the outer periphery of the floater side hinge part 41, and when an upward force is generated in the floater 4, the upward force does not cause the floater side engagement teeth 42 to press the valve body side engagement teeth 32 in the direction in which the valve body 3 closes. Therefore, even in the embodiment of Fig. 6(c), the valve body 3 is in a state of being suspended so as to be free to swing, and naturally rotates in the closing direction due to its own weight, so that the backflow water collides with the downstream side surface 33 of the valve body 3 before the upstream side back surface 34, and the valve body 3, which is subjected to pressure from the backflow water, naturally and smoothly rotates in the direction in which the outlet opening 51 is closed.

[0052] There are no particular limitations on the rotation range of the valve body 3 and the rotation range of the floater 4, but in the first embodiment, in order to ensure smooth flow of forward flow drainage and high degree of obstruction of the valve body 3 when backflow occurs, the rotation range of the valve body 3 is set to 60 to 80° from the outlet opening 51 (valve seat portion 52), and the rotation range of the floater 4 is set to 95 to 145° from the outlet opening 51 (valve seat portion 52).

[0053] <Backflow prevention system> Figure 7 shows an oblique view illustrating an overall overview of a backflow prevention system 2 (partially transparent) according to the first embodiment of the present invention, and Figure 8 shows a B-B cross-sectional view of the backflow prevention system 2 shown in Figure 7.

[0054] As shown in FIGS. 7 and 8, the backflow prevention system 2 of the first embodiment is constructed by attaching the above-mentioned backflow prevention joint 1 of the present invention to the inlet 61 of a bottomed catch basin 6.

[0055] More specifically, the catch basin 6 used in the backflow prevention system 2 of the first embodiment includes a bottom 60, an inlet 61 opening horizontally, an outlet 62 communicating with the inlet 61 and opening horizontally, and an inspection hatch 63 communicating with the inlet 61 and the outlet 62 and opening upward. In this embodiment, the inlet 61, the outlet 62, and the inspection hatch 63 all have a receiving port shape, and an upstream connecting pipe 71, a downstream connecting pipe 72, and a riser pipe 70 are connected to the inside of each of the receiving ports 61, 62, and 63.

[0056] In the backflow prevention system 2 of the first embodiment, the drain manhole 6, the upstream connecting pipe 71, the downstream connecting pipe 72 and the riser pipe 70 are formed from polyvinyl chloride resin, but there is no particular limitation on the materials used, and known materials such as plastics can be used.

[0057] In the first embodiment of the backflow prevention system 2, the backflow prevention fitting 1 of the present invention is installed by inserting the inlet opening 50 of the backflow prevention fitting 1 from inside the drain manhole 6 into the inlet 61, and a gasket 53 is provided on the outer periphery of the valve pipe 5, so that the outer periphery of the valve pipe 5 and the inner periphery of the inlet 61 are liquid-tightly sealed, and the backflow prevention fitting 1 does not easily fall off from the inlet 61.

[0058] In the backflow prevention system 2 of the first embodiment, the catch basin 6 has an inspection hatch 63 that opens upward above the inlet 61 and the outlet 62, so that the valve body 3 and the floater 4 do not interfere with the inner walls of the catch basin 6 or the riser pipe 70, and their movement is not hindered. In addition, a partition-shaped insertion stopper 55 is provided on the upper part of the valve pipe 5, upstream of the hinge support part 54, so that the backflow prevention joint 1 only needs to be pushed in until the insertion stopper 55 abuts against the inner walls of the catch basin 6 or the riser pipe 70, and excessive insertion is prevented from interfering with the inner walls of the catch basin 6, and hindering their movement.

[0059] According to the first embodiment of the backflow prevention system 2, the backflow prevention fitting 1 attached to the inlet 61 of the drainage manhole 6 inclines the outlet opening 51 of the valve pipe 5 so that it progresses from the upstream side to the downstream side as it moves vertically or from top to bottom, thereby increasing the blocking ability of the valve body 3 when backflow occurs and reliably preventing the flow of backflow water.

[0060] In addition, according to the first embodiment of the backflow prevention system 2, one or more engagement teeth 32, 42 are provided on the outer periphery of the hinge portion 31 on the valve body side and the outer periphery of the hinge portion 41 on the floater side, so that when a downward force is generated on the floater 4 due to its own weight, the downward force causes the floater side engagement tooth 42 to press the valve body side engagement tooth 32 in the direction in which the valve body 3 opens the outlet opening 51.Therefore, under normal circumstances, the valve body 3 is kept with the outlet opening 51 open, ensuring a smooth flow of forward flow drainage even when the amount of forward flow drainage is small, and no clogging occurs due to foreign matter contained in the drainage.

[0061] 2. Second embodiment <Backflow prevention joint> Fig. 9 shows a perspective view illustrating the overall outline of a backflow prevention joint 1a according to a second embodiment of the present invention, and Fig. 10 shows a CC cross-sectional view of the backflow prevention joint 1a shown in Fig. 9. Of the backflow prevention joint 1a shown in Fig. 9, Fig. 11 shows a perspective view illustrating the valve body 3a, Fig. 12 shows a perspective view illustrating the floater 4a, and Fig. 13 shows a perspective view illustrating the valve pipe 5a.

[0062] 9 and 10, the backflow prevention joint 1 of the second embodiment includes a cylindrical valve pipe 5a (FIG. 13) having an inlet opening 50a and an outlet opening 51a, a valve body 3a (FIG. 11) rotatably supported near the outlet opening 51a of the valve pipe 5a, and a floater 4a (FIG. 12) having a buoyancy generating part 40a and rotatably supported on the valve pipe 5a in the same manner as the valve body 3a. In the second embodiment, the floater 4a is configured separately and independently from the valve body 3a so that the gravity generated in the floater 4a and the buoyancy generated in the buoyancy generating part 40a can work efficiently, and the buoyancy generating part 40a of the floater 4a is arranged so that it can rotate away from the valve body 3a in an area downstream of the valve body 3a and / or an area above the valve body 3a.

[0063] In the second embodiment, the backflow prevention joint 1a is made of polyvinyl chloride resin, but there is no particular limitation on the material used, and known materials such as plastics can be used.

[0064] <Valve body> The backflow prevention joint 1a of the second embodiment is provided with a valve body 3a for opening and closing a valve seat portion 52a formed in an outlet opening 51a of a valve pipe 5a described later. The shape of the valve body 3a is not particularly limited as long as it can abut against and close the valve seat portion 52a, and in the second embodiment, the downstream surface 33a of the valve body 3a has a shape that is concave from the downstream side to the upstream side (the upstream back surface 34a has a shape that bulges from the downstream side to the upstream side) (FIG. 10).

[0065] In this case, the valve body 3a does not receive a large force even when the wastewater collides with the upstream back surface 34a that bulges toward the upstream side, but receives a large force when the wastewater collides with the downstream surface 33a that is recessed toward the upstream side. Therefore, when backflow occurs, the backflow water mainly collides with the downstream surface 33a of the valve body 3a, so the valve body 3a receives a large force and operates to close the outlet opening 51a, and can reliably suppress the backflow of wastewater. In the second embodiment, a groove portion 35a is provided at the peripheral portion of the valve body 3a at a position where it abuts against the valve seat portion 52a, and a packing (not shown) made of an elastic material such as rubber can be fitted into the groove portion 35a to improve the sealing performance with the outlet opening 51a.

[0066] A radially extending valve body hinge portion 31a is formed on the upper peripheral edge of the valve body 3a, and a gear-shaped valve body engagement tooth 32a consisting of two or more teeth protruding in the radial direction from the outer peripheral surface is formed on the outer periphery of the rotation axis O of the valve body hinge portion 31a. The shape and number of the valve body engagement tooth 32a are not particularly limited, but in the second embodiment, one tooth of the valve body engagement tooth 32a is a convex part having a smooth triangular cross section, and may be formed from a convex part and / or a concave part as long as it forms the teeth of a gear. In addition, the valve body engagement tooth 32a may be one or two or more as long as it can engage with the floater engagement tooth 42a when the floater 4a rises and falls. For example, one floater side engagement tooth 42a is formed on the outer peripheral surface of the floater side hinge portion 41a, and two or more valve body side engagement teeth 32a are formed on the outer peripheral surface of the valve body side hinge portion 31a so as to sandwich the floater side engagement tooth 42a from the front and rear.

[0067] <Floater> The backflow prevention joint 1a of the second embodiment is equipped with a floater 4a to assist the movement of the valve body 3a. The floater 4a has a buoyancy generating part 40a, and is not particularly limited as long as it generates a force to rotate the valve body 3a in the opening direction by the weight of the floater 4a and has a shape, structure, and material that can generate buoyancy against the weight of the floater 4a in water. In the second embodiment, the buoyancy generating part 40a is set so that the rotational moment generated by the weight of the floater 4a at the rotation axis P of the floater 4a is larger than the rotational moment generated by the weight of the valve body 3a at the rotation axis O of the valve body 3a, and the rotational moment generated by the buoyancy of the buoyancy generating part 40a at the rotation axis P of the floater 4a is set so that it is larger than the rotational moment generated by the weight of the floater 4a.

[0068] As shown in Fig. 10, in the second embodiment, the buoyancy generating part 40a of the floater 4a is formed as a hollow plastic structure having a spherical shape because it is strong and easy to manufacture. The buoyancy generating part 40a is connected to the floater side hinge part 41a via a round bar-shaped rod 45a, and the magnitude of the rotation moment generated on the rotation axis P by the buoyancy of the buoyancy generating part 40a can be adjusted by adjusting the size of the buoyancy generating part 40a and the length of the rod 45a.

[0069] On the outer periphery of the rotation axis P of the floater side hinge part 41a, gear-shaped floater side engagement teeth 42a consisting of two or more teeth protruding in the radial direction from the outer periphery are formed. There is no particular restriction on the shape or number of the floater side engagement teeth 42a, but in the second embodiment, one tooth of the floater side engagement teeth 42a is a convex part having a smooth triangular cross section like the valve body side engagement teeth 32a, and may be formed from a convex part and / or a concave part as long as it forms gear teeth. In addition, the floater side engagement teeth 42a may be one or two or more as long as the number of teeth can engage with the valve body side engagement teeth 32a when the floater 4a rises and falls. For example, there may be a case where one valve body side engagement tooth 32a is formed on the outer periphery of the valve body side hinge part 31a, and two or more floater side engagement teeth 42a are formed on the outer periphery of the floater side hinge part 41a so as to sandwich the valve body side engagement teeth 32a from the front and rear.

[0070] 9 and 12, in the second embodiment, the floater side engagement teeth 42a are divided into a first row of floater side engagement teeth 420a and a second row of floater side engagement teeth 421a, and the first row of floater side engagement teeth 420a and the second row of floater side engagement teeth 421a are arranged in a staggered manner. By dividing the floater side engagement teeth 42a into the first row of floater side engagement teeth 420a and the second row of floater side engagement teeth 421a and arranging them in a staggered manner, the pitch of the first and second rows of floater side engagement teeth 420a, 421a can be twice the pitch of the valve body side engagement teeth 32, respectively, making it difficult for dirt and the like to adhere or get caught between the first and second rows of floater side engagement teeth 420a, 421a.

[0071] <Valve pipe> 13, the valve pipe 5a has a substantially circular inlet opening 50a for attachment to an inlet of a catch basin or the like or an outlet of a pipe (neither of which are shown), and a substantially circular outlet opening 51a that communicates with the inlet opening 50a and forms a valve seat 52a that abuts against the valve body 3a. A groove is provided in the circumferential direction on the outer periphery of the valve pipe 5a, and a packing 53a made of an elastic material such as rubber is fitted into the groove to improve the sealing performance with the inlet of a catch basin or the outlet of a pipe to which the backflow prevention joint 1a is attached.

[0072] In the second embodiment, the valve pipe 5a is a short straight pipe with a circular cross section, but it does not necessarily have to be entirely straight and may include a curved pipe section. The valve pipe 5a does not necessarily have to have a uniform diameter, and may be configured as a differential pipe joint in which the inlet opening 50a and the outlet opening 51a have different diameters.

[0073] In the second embodiment, the outlet opening 51a (valve seat portion 52a) of the valve pipe 5a is formed in the vertical direction (FIG. 10), but may be formed to be inclined so as to advance from the upstream side to the downstream side as it goes from top to bottom (not shown). When the outlet opening 51a (valve seat portion 52a) of the valve pipe 5a is shaped as described above, the rotation angle required for the valve body 3a to close the outlet opening 51a (valve seat portion 52a) is smaller than when the outlet opening 51a (valve seat portion 52a) is retreated to the upstream side as it goes from top to bottom, so that the blocking ability of the outlet opening 51a by the valve body 3a is improved.

[0074] In addition, in the second embodiment, under normal circumstances, the movement of the valve body 3a is linked to the movement of the floater 4a which attempts to descend under its own weight, and the weight of the floater 4a causes the valve body 3a to keep the outlet opening 51a (valve seat portion 52a) open, thereby ensuring a smooth flow of forward flow drainage even when the amount of forward flow drainage is small, and no clogging occurs due to foreign matter contained in the drainage.

[0075] 9, 10 and 13, a hinge support part 54a is provided on the upper part of the valve pipe 5a for rotatably supporting the valve body side hinge part 31a of the valve body 3a and the floater side hinge part 41a of the floater 4a. The shape and number of the hinge support parts 54a are not particularly limited, and the hinge support parts 54a may be divided into a first hinge support part for supporting the valve body side hinge part 31a and a second hinge support part for supporting the floater side hinge part 41.

[0076] In the second embodiment, the hinge support part 54a is disposed on the side of the valve body side hinge part 31a such that the shaft hole of the hinge support part 54a aligns with the shaft hole of the valve body side hinge part 31a, and the valve body 3a is rotatably supported by inserting one pin O through each shaft hole. The hinge support part 54a is disposed on the side of the floater side hinge part 41a above the valve body side hinge part 31a such that the shaft hole of the hinge support part 54a aligns with the shaft hole of the floater side hinge part 41a, and the floater 4a is rotatably supported by inserting one pin P through each shaft hole.

[0077] The configuration of the valve body side hinge portion 31a, the floater side hinge portion 41a and the hinge support portion 54a may be such that a pair of hinge support portions 54a are provided on the valve tube 5a so as to sandwich one valve body side hinge portion 31a or one floater side hinge portion 41a from both sides, as in the second embodiment, or, although not shown, a pair of valve body side hinge portions or a pair of floater side hinge portions may be provided on the valve body or the floater so as to sandwich one hinge support portion of the valve tube from both sides, and in order to distribute the force applied to the pin as evenly as possible, it is preferable to have at least two or more of either the valve body side and floater side hinge portions or the hinge support portions.

[0078] <Valve and floater movement> Fig. 14 shows a partial cross-sectional view that shows the movement of the valve body 3a and the floater 4a of the backflow prevention joint 1a according to the second embodiment. In Fig. 14, (a) shows the state of the valve body 3a and the floater 4a when basically no backflow water is occurring, and (b) shows the state when the backflow water raises the floater 4a and the valve body 3 closes the outlet opening 51. The movement of the valve body 3a and the floater 4a will be explained below in the order of (a) and (b) of Fig. 14.

[0079] <Aspects of (a)> FIG. 14(a) shows a normal state in which no backflow water is generated in a catch basin or the like to which the backflow prevention joint 1a according to the second embodiment is attached, and only forward flow drainage flows. In this case, no buoyancy is generated in the buoyancy generating part 40a, and the rotational moment generated in the floater side hinge part 41a due to the weight of the floater 4a is larger than the rotational moment generated in the valve body side hinge part 31a due to the weight of the valve body 3a. Therefore, a downward force is generated in the floater 4a, and the floater side engagement teeth 42a press the valve body side engagement teeth 32a in the direction in which the valve body 3a opens the outlet opening 51a, so that the valve body 3a maintains the outlet opening 51a of the valve pipe 5a in an open state. In other words, the downward movement of the floater 4a connects and links the floater side engagement teeth 42a with the valve body side engagement teeth 32a, and rotates the valve body 3a in the opening direction.

[0080] 14(a), when backflow water or the like occurs and an upward force is generated on the floater 4a due to the buoyancy generated in the buoyancy generating part 40a, the upward force causes the floater side engagement teeth 42a to press the valve body side engagement teeth 32a in the direction in which the valve body 3a closes the outlet opening 51a, in other words, the floater side engagement teeth 42a engage with the valve body side engagement teeth 32a, so that the valve body 3a reliably closes the outlet opening 51a without malfunctioning. In other words, the upward movement of the floater 4a connects and links the floater side engagement teeth 42a with the valve body side engagement teeth 32a, rotating the valve body 3a in the closing direction.

[0081] Thus, in the embodiment shown in Figure 14(a), one or more valve body side engagement teeth 32a are provided on the outer periphery of the valve body side hinge portion 31a, and one or more floater side engagement teeth 42a are provided on the outer periphery of the floater side hinge portion 41a, and when a downward force is generated on the floater 4a due to its own weight, the downward force causes the floater side engagement teeth 42a to press the valve body side engagement teeth 32a in the direction in which the valve body 3a opens the outlet opening 51a, so that under normal circumstances, the valve body 3a maintains the outlet opening 51a in an open state, ensuring a smooth flow of forward flow drainage even when the amount of forward flow drainage is small, and no clogging occurs due to foreign matter contained in the drainage.

[0082] In the backflow prevention joint 1a, if the rotation range of the valve body 3a in the opening direction becomes too large, backflow water may collide with the upstream back surface 34a of the valve body 3a when a backflow occurs, and the valve body 3a may not be able to close. Therefore, in the second embodiment, when the floater 4a rises, the valve body 3a, which rotates in the direction to open the outlet opening 51a in conjunction with the floater 4a's movement, is configured to abut against the floater 4a, thereby restricting the rotation range of the valve body 3a in the opening direction. In addition, although not shown, the rotation range of the valve body 3a in the opening direction may be restricted by providing a stopper on the hinge support part 54a that supports the valve body side hinge part 31a and engaging the valve body side engagement tooth 32a with the stopper.

[0083] In this way, in the backflow prevention fitting 1a of the second embodiment, the floater 4a or a dedicated stopper functions as a stopper that restricts the rotation range of the valve body 3a, ensuring that backflow water collides with the downstream surface 33a of the valve body 3a, and ensuring that the valve body 3a rotates to the closing side without malfunctioning due to backflow water.

[0084] <Aspects of (b)> 14(b) shows a state in which backflow water (not shown) occurs in a catch basin or the like to which the backflow prevention joint 1a according to the second embodiment is attached, causing the floater 4a to rise and the valve body 3a to close the outlet opening 51a. In this case, buoyancy is generated in the buoyancy generating part 40a by the backflow water, and the rotational moment generated in the floater side hinge part 41a by the buoyancy of the buoyancy generating part 40a is greater than the rotational moment generated in the floater side hinge part 41a by the weight of the floater 4a and greater than the rotational moment generated in the valve body side hinge part 31a by the weight of the valve body 3a. Therefore, a total upward force is generated in the floater 4a, and at this time, the upward force causes the floater side engagement teeth 42 to press the valve body side engagement teeth 32a in the direction in which the valve body 3a closes the outlet opening 51a; in other words, the floater side engagement teeth 42a engage with the valve body side engagement teeth 32a, so the valve body 3a reliably closes the outlet opening 51a without malfunctioning. In other words, the upward movement of the floater 4a connects and links the floater side engagement teeth 42a with the valve body side engagement teeth 32a, rotating the valve body 3a in the closing direction.

[0085] Thus, in the embodiment shown in Figure 14(b), one or more valve body side engagement teeth 32a are provided on the outer periphery of the valve body side hinge portion 31a, and one or more floater side engagement teeth 42a are provided on the outer periphery of the floater side hinge portion 41a.When an upward force is generated on the floater 4a, the upward force causes the floater side engagement teeth 42a to press the valve body side engagement teeth 32a in the direction of closing the valve body 3a, so that the valve body 3a reliably blocks the outlet opening 51a without malfunction and maintains that state.

[0086] As a result, in the embodiment shown in Figure 14(b), the opening and closing movement of the valve body 3a is linked to the movement of the floater 4a, both when the floater 4a descends due to its own weight and when it rises due to the buoyancy generated in the buoyancy generating section 40a.

[0087] <Backflow prevention system> Figure 15 shows an oblique view illustrating an overall overview of a backflow prevention system 2a (partially transparent) according to a second embodiment of the present invention, and Figure 16 shows a DD cross-sectional view of the backflow prevention system 2a shown in Figure 15.

[0088] As shown in FIGS. 15 and 16, a backflow prevention system 2a of the second embodiment is constructed by attaching the above-mentioned backflow prevention joint 1a of the present invention to an inlet 61a of a bottomed catch basin 6a.

[0089] More specifically, the catch basin 6a used in the backflow prevention system 2a of the second embodiment includes a bottom 60a, an inlet 61a opening horizontally, an outlet 62a communicating with the inlet 61a and opening horizontally, and an inspection port 63a communicating with the inlet 61a and the outlet 62a and opening upward. In this embodiment, the inlet 61a, the outlet 62a, and the inspection port 63a all have a socket shape, and an upstream connecting pipe 71a, a downstream connecting pipe 72a, and a riser pipe 70a are connected to the inside of each of the sockets 61a, 62a, and 63a.

[0090] In the second embodiment of the backflow prevention system 2a, the drain manhole 6a, the upstream connecting pipe 71a, the downstream connecting pipe 72a and the riser pipe 70a are formed from polyvinyl chloride resin, but there is no particular limitation on the materials used, and known materials such as plastic can be used.

[0091] In the second embodiment of the backflow prevention system 2a, the backflow prevention fitting 1a of the present invention is installed by inserting the inlet opening 50a of the backflow prevention fitting 1a from inside the drainage manhole 6a into the inlet 61a, and a gasket 53a is provided on the outer periphery of the valve pipe 5a, so that the outer periphery of the valve pipe 5a and the inner periphery of the inlet 61a are liquid-tightly sealed, and the backflow prevention fitting 1a does not easily fall off from the inlet 61a.

[0092] In the second embodiment of the backflow prevention system 2a, the drain manhole 6a is provided with an inspection port 63a that opens upward at the top of the inlet 61a and the outlet 62a, so that the valve body 3a and the floater 4a do not interfere with the drain manhole 6a or the inner wall of the riser pipe 70a, etc., and their movement is not hindered.

[0093] According to the second embodiment of the backflow prevention system 2a, the backflow prevention fitting 1a attached to the inlet 61a of the drainage manhole 6a inclines the outlet opening 51a of the valve pipe 5a so that it progresses from the upstream side to the downstream side as it moves vertically or from top to bottom, thereby increasing the blocking ability of the valve body 3a when backflow occurs and reliably preventing the flow of backflow water.

[0094] In addition, according to the second embodiment of the backflow prevention system 2a, one or more engagement teeth 32a, 42a are provided on the outer periphery of the hinge portion 31a on the valve body side and the outer periphery of the hinge portion 41a on the floater side, so that when a downward force is generated on the floater 4 due to its own weight, the downward force causes the floater side engagement tooth 42a to press the valve body side engagement tooth 32a in the direction in which the valve body 3a opens the outlet opening 51a.Therefore, under normal circumstances, the valve body 3a is kept in an open state, ensuring a smooth flow of forward flow drainage even when the amount of forward flow drainage is small, and no clogging occurs due to foreign matter contained in the drainage.

[0095] On the other hand, when an upward force is generated on the floater 4a due to the buoyancy generated in the buoyancy generating section 40a, the upward force causes the floater side engagement tooth 42a to press the valve body side engagement tooth 32a in the direction in which the valve body 3a closes the outlet opening 51a, so that when backflow water occurs, the valve body 3a reliably blocks the outlet opening 51a without malfunctioning, thereby preventing the backflow of wastewater. [Explanation of symbols]

[0096] 1,1a·····Backflow prevention joint 2,2a Backflow prevention system 3, 3a... Valve body 30... Packing 31, 31a: Valve body side hinge part 32, 32a: Valve body side engagement teeth 33,33a...downstream surface 34, 34a...Upstream side back 35a...Groove 4,4a... Floater 40, 40a... Buoyancy generating section 41, 41a Floater side hinge part 410... First protrusion 411... Second protrusion 42, 42a... Floater side engagement teeth 420a... 1st row floater side engagement teeth 421a... 2nd row of floater side engaging teeth 43...Dish part 44 Cap part 45a·····Rod 5,5a...Valve pipe 50,50a...Inlet opening 51,51a...Exit opening 52,52a...Valve seat part 53, 53a... Packing 54, 54a Hinge support part 55 Insertion stop 6,6a·····Drainage manhole 60,60a···Bottom 61,61a...Inlet 62,62a...outlet 63, 63a Inspection hatch 70,70a···Rise pipe 71, 71a...Upstream connecting pipe 72, 72a Downstream connecting pipe O...Valve disc rotation axis P... Rotation axis of the floater

Claims

1. a valve pipe having an inlet opening and an outlet opening; a valve body having a valve body side hinge portion rotatably supported by a first hinge support portion provided near the outlet opening of the valve pipe; a floater having a buoyancy generating portion and a floater-side hinge portion rotatably supported by a second hinge support portion provided in the vicinity of the outlet opening of the valve pipe; In a backflow prevention joint comprising: The valve body side hinge portion is provided with one or more valve body side engagement teeth, The floater side hinge portion is provided with one or more floater side engagement teeth, and A backflow prevention fitting characterized in that when a downward force is generated on the floater, the downward force causes the floater side engaging teeth to press the valve body side engaging teeth in the direction in which the valve body opens.

2. 2. The backflow prevention joint according to claim 1, wherein the range of rotation of the valve body in the opening direction is restricted by the valve body abutting against the floater.

3. A backflow prevention joint as described in claim 1, characterized in that when an upward force is generated in the floater, the floater side engagement teeth do not press the valve body side engagement teeth in the direction in which the valve body closes due to the upward force.

4. A backflow prevention joint as described in claim 1, characterized in that when an upward force is generated in the floater, the upward force causes the floater side engagement teeth to press the valve body side engagement teeth in a direction in which the valve body closes.

5. a valve pipe having an inlet opening and an outlet opening; a valve body rotatably supported near an outlet opening of the valve pipe; a floater having a buoyancy generating portion and rotatably supported in the vicinity of the outlet opening of the valve pipe; A connecting means for connecting or disconnecting the operation of the valve body and the operation of the floater; In the backflow prevention joint, the valve body and the floater are connected by the connecting means. The downward movement of the floater is connected to rotate the valve body in a direction to open the valve body; and A backflow prevention joint characterized in that the upward movement of the floater is uncoupled so as not to rotate the valve body in the closing direction.

6. 6. The backflow prevention joint according to claim 1, wherein the outlet opening of the valve pipe is inclined so as to progress from the upstream side to the downstream side as it extends vertically or from top to bottom.

7. An inlet opening in a horizontal direction; an outlet port communicating with the inlet port and opening in a horizontal direction; and an inspection hatch communicating with the inlet and the outlet and opening upward; In a bottomed catch basin equipped with A backflow prevention system comprising the backflow prevention joint according to claim 6 attached to the inlet.

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