Drainpipe ventilation system

Abstract

To provide a drainpipe ventilation system allowing inner pressure and backflow water in a drainpipe to be stably discharged.SOLUTION: In a drainpipe ventilation system 1, an upper opening lid 3 for closing an upper opening 11 of a drain frame body 2 has an external ventiduct 16 that communicates an inner space 13 and an outer space of the drain frame body 2, and a drain port lid 5 for closing a drain port communicating with a drainpipe has an inner ventiduct that communicates the inside of the drainpipe and the inner space 13, and a closing valve 22 for closing the inner ventiduct. Such a configuration allows inner pressure and backflow water to be discharged through the inner ventiduct and the outer ventiduct 16 when the inner pressure of the drainpipe increases and the backflow water occurs.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a drainage pipe ventilation system that is installed in an opening such as a manhole or inspection hatch to close the opening. [Background technology]

[0002] A drain pipe, such as a sewer pipe, is known to be connected to a space in a protective housing buried underground and open to the ground through an upper opening of the protective housing. For example, Patent Document 1 proposes a configuration including an outer lid (protective housing lid) that closes the upper opening and an inner lid (cleaning port lid) that closes a drain outlet (cleaning port) that opens into the space in the protective housing and communicates with the drain pipe. In this conventional configuration, a closed communication hole is formed in the inner lid, and the communication hole can be opened by cutting the communication hole. When the communication hole is opened, if internal pressure in the drain pipe increases or backflow occurs due to heavy rain or other reasons, the internal pressure and backflow can be released through the communication hole, thereby preventing damage to the drain pipe and malfunctions in upstream drainage equipment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication number 6-9076 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional configuration of Patent Document 1, the internal pressure of the drain pipe and backflow water cannot be released to the outside unless the communication hole is cut and opened. Therefore, before a heavy rainfall occurs, a worker must enter the space of the protective housing and cut the communication hole. However, in recent years, there has been an increase in cases where localized heavy rainfall occurs in a short period of time, making it difficult to predict the occurrence of a heavy rainfall and open the communication hole immediately before the heavy rainfall. Furthermore, if the communication hole is not opened, the internal pressure of the drain pipe and backflow water cannot be released to the outside, which could result in damage to the drain pipe.

[0005] The present invention proposes a drain cover and drain pipe ventilation equipment that can stably release the internal pressure and backflow water of a drain pipe. [Means for solving the problem]

[0006] The present invention is a drain pipe ventilation equipment comprising a drain frame body having an upper opening that opens upward and an internal space that communicates with the inside of a drain pipe via a drain outlet section provided below the upper opening, an upper opening cover that is attached to the upper opening and closes the upper opening, and a drain outlet cover that is attached to the drain outlet section and closes the drain outlet section, wherein the upper opening cover has an external ventilation path that connects the external air space above the upper opening cover with the internal space of the drain frame body, and the drain outlet cover has an internal ventilation path that connects the inside of the drain pipe with the internal space and a closing valve section that closes the internal ventilation path.

[0007] In this configuration, the internal pressure and backflow water of the drain pipe can be released into the internal space through the internal ventilation passage, and the internal pressure and backflow water released from the internal ventilation passage can be released into the external space through the external ventilation passage of the upper opening cover. This makes it possible to stably and reliably prevent the drain pipe from being damaged or the upstream drainage equipment from being adversely affected by an increase in internal pressure or backflow water caused by heavy rain, etc.

[0008] In the drain pipe ventilation equipment of the present invention described above, the drain outlet cover is configured so that the closing valve portion can be converted between a closed state in which the internal ventilation passage is closed and an open state in which it is raised from the closed state to open the internal ventilation passage, and is equipped with an internal pressure release means that converts the closing valve portion from the closed state to the open state using the internal pressure of the drain pipe when the internal pressure of the drain pipe reaches a predetermined pressure or higher, and it is proposed that the upper opening cover be configured so that the external ventilation passage has an opening area that is equal to or larger than the opening area of ​​the internal ventilation passage in the open state.

[0009] In this configuration, when the internal pressure of the drain pipe (including the internal pressure due to backflow water and the water pressure due to backflow water) reaches or exceeds a predetermined pressure, the internal air vent opens, allowing the internal pressure and backflow water to be released through the internal air vent. In this configuration, the opening area of ​​the external air vent is equal to or larger than the opening area of ​​the internal air vent, so the pressure and backflow water released into the internal space through the internal air vent can be released smoothly and stably to the external air space through the external air vent.

[0010] The opening areas of the external air vent passage and the internal air vent passage refer to at least one of the upper and lower ends of each air vent passage. In this configuration, it is preferable that the upper end opening of the external air vent passage (the opening on the external air space side) has a larger opening area than the upper end opening of the internal air vent passage (the opening on the internal space side). Furthermore, it is preferable that the upper end opening of the external air vent passage has a larger opening area than the upper end opening of the internal air vent passage, and that the lower end opening of the external air vent passage has a larger opening area than the lower end opening of the internal air vent passage. Furthermore, it is preferable that the upper end opening and the lower end opening of the external air vent passage have a larger opening area than either the upper end opening or the lower end opening of the internal air vent passage.

[0011] In the drain pipe ventilation equipment of the present invention described above, the drain outlet cover is configured so that the closing valve portion can be converted between a closed state in which the internal ventilation passage is closed and an open state in which it is raised from the closed state to open the internal ventilation passage, and is equipped with an internal pressure release means that converts the closing valve portion from the closed state to the open state using the internal pressure of the drain pipe when the internal pressure of the drain pipe reaches a predetermined pressure or higher, and it is proposed that the upper opening cover be configured so that the external ventilation passage has an opening area that is smaller than the opening area of ​​the internal ventilation passage in the open state.

[0012] In this configuration, when the internal pressure of the drain pipe reaches a predetermined pressure or higher, the internal air vent opens, allowing the internal pressure and backflow water to be released through the internal air vent. In this configuration, the opening area of ​​the external air vent is smaller than the opening area of ​​the internal air vent, so the amount of pressure and backflow water released from the external air vent to the external space per unit time can be reduced compared to the internal pressure and backflow water released into the internal space through the internal air vent.

[0013] In this configuration, the opening area of ​​the external air vent passage and the internal air vent passage refers to at least one of the upper and lower ends of each air vent passage, as in the configuration described above. In this configuration, the upper opening of the external air vent passage is preferably larger in opening area than the upper opening of the internal air vent passage. Furthermore, it is preferable that the upper and lower openings of the external air vent passage have larger opening areas than the upper and lower openings of the internal air vent passage. Furthermore, it is preferable that the upper and lower openings of the external air vent passage have larger opening areas than either the upper or lower openings of the internal air vent passage.

[0014] In the drain pipe ventilation system of the present invention described above, it is preferable that the upper opening cover is provided with a plurality of the external ventilation paths.

[0015] In this configuration, the pressure and backflow water released into the external air space can be dispersed by the multiple external vent passages, thereby suppressing the force of the pressure and backflow water released from each external vent passage. Furthermore, since multiple external vent passages are provided, even if one external vent passage becomes clogged or damaged by foreign matter (such as dirt), the pressure and backflow water can be released through the other external vent passages. Furthermore, since multiple external vent passages are provided, it is possible to relatively reduce the opening area of ​​each external vent passage while maintaining the desired amount of pressure and backflow water released. This also has the excellent advantage of suppressing the intrusion of foreign matter through the upper opening lid.

[0016] In the drain pipe ventilation equipment of the present invention described above, it is proposed that the external ventilation path has a lower end opening opened on the underside of the upper opening cover and an upper end opening opened on the upper surface of the upper opening cover, which are arranged at horizontally offset positions from each other.

[0017] With this configuration, it is difficult for passersby passing over the upper opening lid to see the internal cavity of the drainage frame through the external ventilation path. This prevents passersby from feeling uneasy due to the internal cavity being visible. Furthermore, the force of the pressure and backflow water released from the external ventilation path can be suppressed between the lower opening and the upper opening, preventing the pressure and backflow water released from the upper opening from adversely affecting people, vehicles, and other passing objects over the upper opening lid.

[0018] In the drain pipe ventilation equipment of the present invention described above, it is proposed that the external ventilation passage be configured to slope upward from the center of the upper opening cover toward the outside.

[0019] In this configuration, the pressure and backflow water released from the external vent passage can be released in an inclined direction outward from the upper opening lid, so the force of the backflow water can be stably suppressed, thereby preventing the pressure and backflow water released from the external vent passage from having an adverse effect on objects passing over the upper opening lid. [Effects of the Invention]

[0020] The drain pipe ventilation equipment of the present invention can release the internal pressure and backflow water of the drain pipe into the external air space above the upper opening cover, thereby preventing the drain pipe from being damaged by the internal pressure and preventing the backflow water from having a negative impact on the upstream drainage equipment. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view showing an installed state of a drainage pipe ventilation system 1 according to an embodiment of the present invention. [Figure 2] 1 is a perspective view showing a drainage frame 2 and an upper opening cover 3 that constitute the drainage pipe ventilation equipment 1. FIG. [Figure 3] 2 is a cross-sectional view showing the upper opening cover 3, the drain frame 2, and the drain outlet cover 5 separated from each other. [Figure 4] 1 is an explanatory diagram showing a pressure release mode in the drain pipe ventilation equipment 1. FIG. [Figure 5]10A and 10B are explanatory views showing a drainage pipe ventilation system 1 according to another example in (A) an installed state and in (B) an open state of a pressure release valve section 42 and a close valve section 22. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] First and second embodiments of the drain pipe ventilation system according to the present invention will be described below. [Example]

[0023] The drain pipe ventilation equipment 1 of the first embodiment is for releasing the internal pressure (including water pressure) that has increased in a drain pipe buried underground and backflow water generated in the drain pipe to the outside (atmosphere) through a vertical pipe 101 that is connected to the drain pipe, and as shown in FIG. 1, it is arranged so as to cover the upper end (outlet 102) of the vertical pipe 101. The drain pipe (not shown) and the vertical pipe 101 are buried underground, and a paved area S is constructed around the drain pipe ventilation equipment 1 using asphalt, concrete, or the like that is paved on the ground G. Here, the outlet 102 that opens at the upper end of the vertical pipe 101 is exposed to the ground G through an opening (not shown) in a base M that is provided on the ground G.

[0024] The drain pipe ventilation equipment 1 comprises an approximately cylindrical drain frame body 2 installed on the base M, an upper opening lid 3 that closes the upper opening 11 of the drain frame body 2, a lid receiving frame 4 attached to the drain outlet portion 102 of the vertical pipe 101, and a drain outlet lid 5 that is attached to the lid receiving frame 4 and closes the drain outlet portion 102.

[0025] As shown in Figures 1 to 3, the drainage frame 2 has a generally cylindrical shape that is open in the vertical direction, and includes at its upper part the upper opening 11 that is closed by the upper opening lid 3, and at its lower part a circular mounting portion 12 that is mounted on the base M. The drainage frame 2 includes an inner space 13 that communicates with the drain outlet portion 102 of the vertical pipe 101, and the inner space 13 is opened upward by the upper opening 11. That is, when the drain outlet lid 5 and the upper opening lid 3 are not attached, the drain outlet portion 102 of the vertical pipe 101 opens upward through the inner space 13 and the upper opening 11 of the drainage frame 2. On the other hand, when the upper opening 11 and the drain outlet portion 102 are closed, the inner space 13 of the drainage frame 2 is closed from the inside of the vertical pipe 101 (the inside of the drain pipe) and the external air space.

[0026] The lid receiving frame 4 has a substantially circular ring shape and is fitted into the drain outlet portion 102 of the vertical pipe 101. When the lid receiving frame 4 is fitted into the drain outlet portion 102, the drain outlet portion 102 is open upward, and when the drain outlet lid 5 is attached to the lid receiving frame 4, the drain outlet portion 102 is closed.

[0027] As shown in Figures 1 to 4, the drain cover 5 has an internal air passage 21 (Figure 4(B)) that connects the upper surface side and the lower surface side, and a closing valve portion 22 that closes the internal air passage 21, and the closing valve portion 22 is provided so as to be movable up and down relative to the internal air passage 21. The closing valve portion 22 has a disk-shaped main valve portion 22a and a pressure-receiving shaft portion 22b that protrudes downward from the main valve portion 22a. The pressure-receiving shaft portion 22b has a shaft portion (not shown) that has a smaller diameter than the main valve portion 22a, and a disk-shaped pressure-receiving portion (not shown) provided at the lower end of the shaft portion.

[0028] The drain lid 5 has, on its upper surface, a valve receiving portion 23 to which the main valve portion 22a of the stop valve portion 22 is attached, and further has a vertical insertion hole 24 that communicates between the valve receiving portion 23 and the underside of the drain lid 5. The stop valve portion 22 has the main valve portion 22a attached to the valve receiving portion 23, and the shaft portion of the pressure-receiving shaft portion 22b inserted into the insertion hole 24, with the pressure-receiving portion of the pressure-receiving shaft portion 22b protruding downward from the insertion hole 24. In this manner, the stop valve portion 22 is attached to the drain lid 5. Here, the shaft portion of the pressure-receiving shaft portion 22b is formed with a smaller diameter than the insertion hole 24 and is able to move freely in the vertical direction through the insertion hole 24, while the pressure-receiving portion of the pressure-receiving shaft portion 22b is formed with a larger diameter than the insertion hole 24 and cannot be inserted through the insertion hole 24.

[0029] With the main valve portion 22a of the stop valve portion 22 attached to the valve receiving portion 23 in this manner, the valve receiving portion 23 and the insertion hole 24 are closed, as shown in FIG. 4(A). This state is the closed state of the internal ventilation path 21. When the stop valve portion 22 is raised from the closed state, the main valve portion 22a moves away from the valve receiving portion 23, as shown in FIG. 4(B), creating a gap 25 between the main valve portion 22a and the valve receiving portion 23, and the insertion hole 24 is opened upward through the gap 25. In this opened state (hereinafter referred to as the open state), the interior of the vertical pipe 101 communicates with the inner space 13 of the drainage frame 2 through the gap 25 and the insertion hole 24 (the gap between the inner peripheral surface of the insertion hole 24 and the shaft portion of the pressure-receiving shaft portion 22b). Here, the gap 25 and the insertion hole 24 (gap with the shaft portion of the pressure-receiving shaft portion 22b) form the internal ventilation passage 21 in an open state. That is, the internal ventilation passage 21 in this embodiment is formed by the main valve portion 22a and the valve receiving portion 23 which form the gap 25, and the insertion hole 24.

[0030] The closing valve portion 22 of this embodiment is maintained in a closed state by its own weight, attached to the valve receiving portion 23 of the drain outlet cover 5, and is raised from the closed state to an open state when it is lifted upward. Then, when this lifting force is released, it descends from the open state to be converted to the closed state.

[0031] The drain outlet cover 5 may also be provided with a locking member to prevent it from coming off the cover receiving frame 4. This locking member may, for example, be provided on the drain outlet cover 5 in a rotatable manner, and may be switched between a locked state in which it engages with the inner wall of the cover receiving frame 4 and an unlocked state in which it is released by the rotation. A locking member of this configuration has an operating means that is rotated on the top surface of the drain outlet cover 5, and can be switched between the locked state and the unlocked state by manually operating the operating means. Here, the operating means may be configured to be operable with a predetermined jig or may be configured to be directly operated by an operator with their hands, and the latter configuration is particularly easy to use as it does not require a jig.

[0032] As shown in FIGS. 1 and 2 , the upper opening lid 3 is provided with a plurality (e.g., 10) of external ventilation passages 16 that penetrate vertically and are spaced apart at predetermined intervals in the circumferential direction. Each external ventilation passage 16 is configured such that an upper end opening 16a that opens on the upper surface of the upper opening lid 3 communicates with a lower end opening 16b that opens on the lower surface of the upper opening lid 3. In this embodiment, the upper end opening 16a is offset radially outward from the lower end opening 16b, and each external ventilation passage 16 is formed with an upward gradient that slopes radially outward from the lower end opening 16b toward the upper opening lid 3. The positional relationship between the upper end opening 16a and the lower end opening 16b is such that the horizontal position of the upper end opening 16a is shifted radially outward from the horizontal position of the lower end opening 16b.

[0033] As described above, the upper opening cover 3 is configured with an external ventilation path 16 that is always open, so that when the upper opening 11 of the drainage frame 2 is closed, the internal space 13 of the drainage frame 2 is connected to the external air space by the external ventilation path 16. As a result, the internal pressure of the internal space 13 of the drainage frame 2 is maintained in a state of approximate equilibrium with the external air pressure of the external air space.

[0034] In this embodiment 1, the total opening area of ​​all the external vent passages 16 provided in the upper opening lid 3 is larger than the opening area of ​​the internal vent passage 21 when the stop valve portion 22 is in an open state. More specifically, each external vent passage 16 in this embodiment is formed with a substantially uniform opening area from the upper end opening 16a to the lower end opening 16b, and the opening areas of the upper end opening 16a and the lower end opening 16b are substantially equal. Meanwhile, the lower end opening area of ​​the internal vent passage 21 is the opening area (the minimum opening area of ​​the internal vent passage 21) due to the gap between the insertion hole 24 of the drain outlet lid 5 and the pressure-receiving shaft portion 22b of the stop valve portion 22, and the upper end opening area of ​​the internal vent passage 21 is the opening area formed between the peripheral end of the valve receiving portion 23 of the drain outlet lid 5 and the main valve portion 22a of the stop valve portion 22. The total opening area, which is the sum of the opening areas of all the external ventilation passages 16, is larger than the lower end opening area and larger than the upper end opening area of ​​the internal ventilation passage 21. As a result, the amount of pressure and backflow water that can pass through all the external ventilation passages 16 (amount passing through per unit time) is larger than the amount that can pass through the internal ventilation passage 21 in an open state (amount passing through per unit time), so that when the internal ventilation passage 21 is open, the pressure and backflow water released from the drain pipe can be smoothly released into the external air space via the external ventilation passage 16.

[0035] In the configuration of this embodiment, the drain frame 2 and the upper opening lid 3 are made of metal, preferably cast iron, steel, or pure iron from the perspective of machining, and more preferably cast iron. The lid receiving frame 4, drain lid 5, and stop valve 22 are made of resin, preferably thermoplastic resin, more specifically rigid polyvinyl chloride resin. The stop valve 22 is attached to the drain lid 5 and is smaller and lighter than the drain lid 5. As a result, the force required to change the stop valve 22 from a closed state to an open state is smaller than the force required to lift the drain lid 5. Therefore, when the internal pressure of the drain pipe increases or when backflow water pressure acts, the stop valve 22 is changed to an open state by the internal pressure or water pressure. Here, the force that changes the stop valve section 22 from the closed state to the open state is the force that lifts the weight of the stop valve section 22, and therefore the internal pressure of the drain pipe and the water pressure of backflow water that change the stop valve section 22 to the open state are determined according to the weight of the stop valve section 22. In other words, the weight of the stop valve section 22 can be set based on the upper limit (threshold) of the internal pressure (and the water pressure of backflow water) that increases in the drain pipe.

[0036] Next, the operation of the drain pipe ventilation system 1 of the first embodiment will be described. Under normal conditions, a sufficient amount of water flows through the drain pipe, and the internal pressure does not increase to the level required to lift the shut-off valve section 22 of the drain pipe ventilation equipment 1, so the shut-off valve section 22 is held in the closed state by its own weight, as shown in Figure 1.

[0037] When the amount of water flowing through the drain pipe increases due to heavy rain or the like, and the internal pressure of the drain pipe exceeds the pressure required to lift the shut-off valve portion 22 of the drain outlet cover 5, the pressure acting on the shut-off valve portion 22 from the vertical pipe 101 causes the shut-off valve portion 22 to rise from the closed state and change to the open state, as shown in Figure 4. As a result, the internal pressure of the drain pipe is released into the internal space 13 of the drain frame 2 via the vertical pipe 101 and the internal air passage 21.

[0038] When pressure is released from the open internal air vent passage 21 to the internal space 13, the pressure increases the internal pressure of the internal space 13, and the increased pressure is released to the external space through the external air vent passage 16 of the top opening lid 3. When the internal pressure in the drain pipe increases in this way, the internal pressure is released to the external space above the top opening lid 3 via the open internal air vent passage 21, the internal space 13, and the external air vent passage 16, thereby suppressing an increase in the internal pressure of the drain pipe. In this embodiment 1, as described above, the total opening area of ​​all the external air vent passages 16 is larger than the opening area of ​​the internal air vent passage 21, so the internal pressure of the drain pipe can be smoothly released to the external space, and the increase in internal pressure of the drain pipe can be more stably suppressed. Furthermore, because the external air vent passage 16 has a shape that slopes upward radially outward, the pressure that passes through the external air vent passage 16 is released diagonally upward along the external air vent passage 16. This makes it possible to suppress the effects of pressure released from the external ventilation passages 16 on objects (people, vehicles, etc.) passing over the upper opening lid 3. For example, it is possible to suppress the risk of pedestrians falling or being injured due to pressure released from the external ventilation passages 16. In particular, in this embodiment, multiple external ventilation passages 16 are provided at intervals in the circumferential direction, and pressure can be released radially from these multiple external ventilation passages 16. This makes it possible to disperse the pressure released into the external airspace, further suppressing the effects on the objects passing by.

[0039] When the internal pressure of the drain pipe decreases while the internal ventilation path 21 is open and becomes lower than the pressure that lifts the closing valve portion 22, the closing valve portion 22 is converted from the open state to the closed state, thereby returning to the normal state.

[0040] Furthermore, if backflow water occurs in the drain pipe during heavy rain or other events, and the water pressure of the backflow water traveling up the vertical pipe 101 exceeds the pressure required to lift the shutoff valve 22 of the drain outlet cover 5, the shutoff valve 22 switches to an open state, and the backflow water is released into the internal space 13 (see Figure 4). This release of backflow water into the internal space 13 increases the internal pressure of the internal space 13, and the backflow water accumulates in the internal space 13, increasing its volume. The increased internal pressure in the internal space 13 is then released to the external space through the external vent passage 16 of the upper opening cover 3, increasing the volume of backflow water. When the internal space 13 is filled with backflow water, the backflow water is released from the external vent passage 16 of the upper opening cover 3 to the external space. This reduces the amount of water flowing back up the drain pipe. In this way, the drain pipe ventilation system 1 operates in the same way as when the internal pressure of the drain pipe increases, even when backflow water occurs.

[0041] The drain pipe ventilation system 1 of the first embodiment includes a drain outlet cover 5 that closes the drain outlet 102 of the vertical pipe 101 and is provided with an internal ventilation passage 21 and a closing valve 22 that opens and closes the internal ventilation passage 21, and an upper opening cover 3 that closes the upper opening 11 of the drain frame 2 and is provided with multiple external ventilation passages 16. With this configuration, when the internal pressure of the drain pipe increases, the internal ventilation passage 21 opens, allowing the pressure released into the internal space 13 to be released through the external ventilation passage 16 to the external space. Similarly, when the water pressure of backflow water generated in the drain pipe increases, the internal ventilation passage 21 opens, allowing the backflow water released into the internal space 13 to be released through the external ventilation passage 16 to the external space. Thus, with the configuration of the first embodiment, increased pressure in the drain pipe and backflow water can be smoothly released to the external space during heavy rain, preventing damage to the drain pipe due to the increased pressure and adverse effects of backflow water on upstream drainage equipment.

[0042] In this embodiment, the upper opening lid 3 is provided with multiple external vent passages 16, and the total opening area of ​​all the external vent passages 16 is larger than the opening area of ​​the internal vent passages 21. This allows the pressure and backflow water released into the internal space 13 by opening the internal vent passages 21 to be more smoothly released from the external vent passages 16 to the external space. Even if some of the external vent passages 16 become clogged or damaged, the pressure and backflow water can be released through the other external vent passages 16. Furthermore, because the external vent passages 16 are shaped to slope upward radially from the lower opening 16b to the upper opening 16a, the pressure and backflow water released from the internal space 13 are released obliquely upward along the external vent passages 16. Because the pressure and backflow water can be released radially through the multiple external vent passages 16, the force of the pressure and backflow water can be suppressed. This makes it possible to prevent pressure and backflow water released from the external ventilation passages 16 from adversely affecting objects passing over the upper opening lid 3. Furthermore, because each external ventilation passage 16 is inclined (the upper end opening 16a and the lower end opening 16b are offset radially), it is possible to prevent foreign matter (such as dirt) from entering through the upper opening lid 3, and it is difficult for passersby passing over the upper opening lid 3 to see the internal space 13 through the external ventilation passages 16, which prevents passersby from becoming anxious.

[0043] In the above-described first embodiment, the internal pressure of the drain pipe and the water pressure of the backflow water that raise the shut-off valve portion 22 in the closed state correspond to the predetermined pressure that converts the shut-off valve portion of the present invention to the open state. The internal air passage 21, the valve receiving portion 23, and the main valve portion 22a and pressure receiving shaft portion 22b that constitute the shut-off valve portion 22 constitute the internal pressure release means of the present invention. [Example]

[0044] The drain pipe ventilation equipment 1 of Example 2 is configured such that the total opening area of ​​the multiple external ventilation passages 16 provided in the upper opening cover 3 is smaller than the opening area of ​​the internal ventilation passage 21 when the closing valve section 22 is in the open state.

[0045] The upper opening lid 3 of the second embodiment has the same number of external air vent passages 16 as those of the first embodiment, provided at predetermined intervals in the circumferential direction (see FIGS. 1 and 2). Similarly to the first embodiment, each external air vent passage 16 is provided so as to slope upward from a lower end opening 16b toward an upper end opening 16a, which is offset radially outward from the lower end opening 16b. That is, the opening area of ​​each external air vent passage 16 of the second embodiment is smaller than that of the first embodiment. Because the total opening area of ​​all the external air vent passages 16 is smaller than the opening area of ​​the internal air vent passage 21, the amount of air passing through all the external air vent passages 16 (the amount of air passing through per unit time) is smaller than the amount of air passing through the internal air vent passage 21 in the open state (the amount of air passing through per unit time). This allows the amount of pressure and backflow water released from the external air vent passages 16 to the external air space to be reduced when the internal air vent passage 21 is open.

[0046] In the configuration of the second embodiment, the configuration other than the external ventilation path 16 is the same as that of the first embodiment described above, and therefore the same components are denoted by the same reference numerals and the description thereof will be omitted.

[0047] The drain pipe ventilation system 1 of Example 2 has the same configuration as Example 1 described above except for the opening area of ​​the external ventilation passage 16. Therefore, similar to Example 1, the internal pressure of the drain pipe or the water pressure of backflow water opens the internal ventilation passage 21, releasing the internal pressure or backflow water into the internal space 13 of the drainage frame 2. In Example 2, the total opening area of ​​the external ventilation passage 16 is smaller than the opening area of ​​the internal ventilation passage 21, so the amount (amount per unit time) of pressure and backflow water released from the external ventilation passage 16 when the internal ventilation passage 21 is opened can be reduced. This reduces the impact of pressure and backflow water released from the external ventilation passage 16 on passing objects. In addition, similar to Example 1 described above, the configuration of Example 2 allows increased pressure and backflow water in the drain pipe during heavy rain to be released to the external space, thereby reducing the risk of damage to the drain pipe due to increased pressure and the adverse impact of backflow water on upstream drainage equipment. Furthermore, similar to the first embodiment, it is possible to prevent foreign matter from entering through the upper opening lid 3, and also to prevent passersby from feeling uneasy.

[0048] The present invention is not limited to the above-described first and second embodiments, and can be modified as appropriate within the scope of the present invention. For example, the dimensions and shapes of the components in the above-described embodiments can be modified as appropriate.

[0049] In the first and second embodiments described above, the number of external vent passages provided in the upper opening lid can be changed as appropriate. The locations of the multiple external vent passages can also be changed as appropriate. For example, multiple external vent passages can be provided at intervals in the circumferential direction on multiple imaginary concentric circles with different radii. Alternatively, multiple external vent passages can be provided at intervals in a straight line.

[0050] The shape of the external ventilation passage can be changed as appropriate in the above-described Examples 1 and 2. For example, an external ventilation passage having a circular or triangular cross section may be provided, or an external ventilation passage having an upper opening and a lower opening with different opening areas may be provided. In the latter configuration in which an external air vent passage is provided, the external air vent passage may be either larger or smaller than the opening area of ​​the internal air vent passage. In a configuration in which the opening area of ​​the external air vent passage is larger than that of the internal air vent passage, it is preferable that the smallest opening area of ​​the external air vent passage (the sum of the opening areas, if there are multiple external air vent passages) is at least larger than the smallest opening area of ​​the internal air vent passage. Furthermore, it is preferable that the opening area of ​​the upper end opening of the external air vent passage (similar to the above, the sum of the opening areas, if there are multiple external air vent passages) is larger than the opening area of ​​the internal air vent passage that opens to the internal space. On the other hand, in a configuration in which the opening area of ​​the external air vent passage is smaller than that of the internal air vent passage, it is preferable that the smallest opening area of ​​the external air vent passage (the sum of the opening areas, if there are multiple external air vent passages) is at least smaller than the smallest opening area of ​​the internal air vent passage. Furthermore, it is preferable that the opening area of ​​the upper end opening of the external air vent passage (similar to the above, the sum of the opening areas, if there are multiple external air vent passages) is smaller than the opening area of ​​the internal air vent passage that opens to the internal space.

[0051] In the first and second embodiments described above, the total opening area of ​​the external vent passages can be set equal to the opening area of ​​the internal vent passage. In this configuration, as in the first embodiment, the internal pressure of the drain pipe and backflow water can be smoothly released through the external vent passage when the internal vent passage is open. Furthermore, this configuration also has the effect of suppressing the amount of water released from the external vent passage compared to the first embodiment.

[0052] In the first and second embodiments described above, the upper opening lid may be configured to include a pressure release means for switching the external vent path between a closed state and an open state. As another example of a drain pipe ventilation system including such a pressure release means, for example, the drain pipe ventilation system 1 shown in FIG. 5 is proposed. In this configuration, the upper opening lid 3 is formed with a generally cone-shaped through-hole 41 penetrating vertically, and a pressure release valve 42 is disposed to open and close the through-hole 41. The through-hole 41 and the pressure release valve 42 constitute the pressure release means. The pressure release valve 42 includes a generally conical main valve 42a that fits over the through-hole 41 and closes it, and a pressure-receiving shaft 42b that protrudes downward from the main valve 42a. The pressure-receiving shaft 42b has a smaller diameter than the through-hole 41 and is inserted into the lower opening of the through-hole 41. The pressure release valve 42 is converted between a closed state (FIG. 5(A)) in which the main valve 42a is fitted over the through-hole 41 and an open state (FIG. 5(B)) in which the main valve 42a is raised from the closed state and moves away from the through-hole 41. In this open state, the gap between the main valve 42a and the through-hole 41 connects the internal space 13 of the drainage frame 2 to the external space. This gap is formed between the generally mortar-shaped through-hole 41 and the generally conical main valve 42a, and forms an external air passage 43 that slopes upward from the center outward. In this alternative configuration, when the internal pressure of the drain pipe increases due to heavy rain or the like and the internal air passage 21 of the drain outlet cover 5 opens, the internal pressure is released into the internal space 13 of the drainage frame 2. If the internal pressure of the internal space 13 subsequently increases and exceeds the predetermined pressure required to lift the pressure release valve 42, the pressure release valve 42 switches from a closed state to an open state, and the external vent passage 43 opens. This releases the internal pressure of the internal space 13 to the external air space via the external vent passage 43. In this alternative example, the pressure release valve 42 is made of resin, just like the closing valve 22, and is lighter in weight than the closing valve 22. This allows for a smooth operation from the opening of the closing valve 22 to the opening of the pressure release valve 42. This alternative configuration also allows for the internal pressure of the drain pipe and backflow water to be released to the external air space, just like the previously described embodiment. Furthermore, because the external vent passage 43 is configured to slope upward from the center outward, it can achieve the same effects as the previously described embodiment.To be more specific, in another example configuration, if the opening area of ​​the external air passage 43 in the open state is larger than (or equivalent to) the internal air passage 21 in the open state, the same effect as in the above-mentioned Example 1 will be achieved, while if the opening area of ​​the external air passage 43 is smaller than the internal air passage 21, the same effect as in the above-mentioned Example 2 will be achieved. [Explanation of symbols]

[0053] 1. Drainage pipe ventilation equipment 2 Drainage frame 3 Top opening lid 5 Drain cover 11 Top opening 13 Inner cavity 16,43 External ventilation passage 16a Top opening 16b Bottom opening 21 Internal ventilation channel 22 Closure valve section 102 Drain port

Claims

1. a drainage frame having an upper opening that opens upward and an inner space that communicates with the inside of the drain pipe via a drain outlet portion provided below the upper opening, the upper opening cover being attached to the upper opening and closing the upper opening; a drain outlet cover attached to the drain outlet portion and closing the drain outlet portion; A drain pipe ventilation system comprising: the upper opening cover has an external ventilation passage that communicates an external space above the upper opening cover with an internal space of the drainage frame, The drain pipe ventilation equipment is characterized in that the drain outlet cover is equipped with an internal ventilation passage that connects the inside of the drain pipe with the inner space, and a closing valve portion that closes the internal ventilation passage.

2. The drain outlet cover is The closing valve portion is configured to be convertible between a closed state in which the internal air passage is closed and an open state in which the internal air passage is opened by being raised from the closed state, and an internal pressure release means is provided for converting the closing valve portion from the closed state to the open state by the internal pressure of the drain pipe when the internal pressure of the drain pipe reaches a predetermined pressure or higher; The upper opening lid is 2. The drain pipe ventilation system according to claim 1, wherein the external ventilation passage has an opening area equal to or larger than the opening area of ​​the internal ventilation passage in the open state.

3. The drain outlet cover is The closing valve portion is configured to be convertible between a closed state in which the internal air passage is closed and an open state in which the internal air passage is opened by being raised from the closed state, and an internal pressure release means is provided for converting the closing valve portion from the closed state to the open state by the internal pressure of the drain pipe when the internal pressure of the drain pipe reaches a predetermined pressure or higher; The upper opening lid is 2. The drain pipe ventilation system according to claim 1, wherein the external ventilation passage has an opening area smaller than the opening area of ​​the internal ventilation passage in the open state.

4. 4. The drain pipe ventilation system according to claim 1, wherein the upper opening cover is provided with a plurality of the external ventilation paths.

5. The external ventilation path is A drain pipe ventilation equipment as described in any one of claims 1 to 3, characterized in that the lower end opening opened on the lower surface of the upper opening cover and the upper end opening opened on the upper surface of the upper opening cover are arranged at horizontally offset positions from each other.

6. The external ventilation path is 6. The drain pipe ventilation system according to claim 5, wherein the upper opening cover is provided so as to slope upward from the center toward the outside.

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