Filtration system

Abstract

The present invention aims to reduce the labor required for maintenance and inspection of a filter membrane unit. The filter system comprises a plurality of filter membrane units (21) and a water collecting pipe (90), wherein the water collecting pipe comprises a main pipe section (91) and a plurality of separate water collecting passages arranged in the axial direction of the main pipe section (91) and connected to the main pipe section (91), wherein filtrate filtered by filter membranes (22) of the plurality of filter membrane units (21) is collected into the main pipe section (91) of the water collecting pipe (90) via a discharge passage and the separate water collecting passages of the water collecting pipe (90), wherein the filter system comprises a locking component (98), wherein the locking component locks the axial movement of the discharge passages of the plurality of filter membrane units (21), wherein the plurality of filter membrane units (21) are respectively provided with an O-ring made of elastic material on the outer peripheral surface of the discharge pipe forming the discharge passage, and when the discharge pipe is inserted into the separate water collecting passage, the axial movement of the discharge pipe is locked by the locking component (98).

Description

Technical Field

[0001] The present invention relates to filtration systems. Background Art

[0002] In the past, a filtration system is known, which includes multiple filtration membrane units, each of which includes a filtration membrane and an outlet for discharging filtrate obtained from the filtration membrane, and includes a water collecting pipe, which includes a main pipe and multiple separate water collecting passages arranged in the axial direction of the above-mentioned main pipe and connected to the above-mentioned main pipe.

[0003] For example, the membrane assembly unit as a filtration system described in Patent Document 1 is provided with a plurality of membrane assemblies as filtration membrane units and a water collection manifold as a water collection pipe. The water collection manifold is provided with a barrel portion as a main pipe portion and a plurality of intermediate connecting portions (individual water collection paths) which are radially connected from the barrel portion relative to the barrel portion and arranged in the axial direction of the barrel portion. In addition, the membrane assembly is provided with a flat filter membrane (hollow fiber membrane) and a shell respectively fixed at both ends in the long side direction of the filter membrane. A water intake port as a drain port is arranged at the end of the filter membrane in the short side direction of one of the two end shells. The water intake port is individually connected to one of the plurality of intermediate connecting portions in the water collection manifold through a pipe. When the filter membrane of each membrane assembly generates an attraction force through the barrel portion and the intermediate connecting portion of the water collection manifold by the power of a pump or the like, the water in the sludge around the filter membrane is attracted to the filter membrane as filtrate. The attracted filtrate is collected in the barrel portion of the water collection manifold via the water intake port of the shell of the membrane assembly, the pipe connected thereto, and the intermediate connecting portion of the water collection manifold.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6319510 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In patent document 1, there is no specific description on how to connect the multiple intermediate connection parts of the water collection manifold and the pipes extending from the water intake ports of the multiple membrane modules. However, in the attached drawings, since the external thread is depicted on the outer peripheral surface of the cylindrical intermediate connection part, it can be considered that the connection is made by a union joint that can be screwed with the external thread. The union joint is a joint in which the internal thread formed on the inner peripheral surface of the rotatable threaded cup is screwed with the external thread on the outer peripheral surface of the pipe as the connection object. In the membrane module unit described in patent document 1, when multiple membrane modules are individually connected to the intermediate connection parts of the water collection manifold through pipes, the threaded cup of the union joint is forced to rotate multiple times to tighten the threads each time the connection is made. In addition, when the individual membrane modules are disassembled for maintenance and inspection, the threaded cup of the union joint is also forced to reverse multiple times to loosen the threads. Furthermore, in order to operate the membrane module unit with the damaged membrane module removed, it is necessary to seal the intermediate connection portion opened by the removal with a screw cap, and at this time, the screw cap must be rotated several times to tighten the screws, which is a laborious operation.

[0009] The present invention has been made in view of the above background, and an object of the present invention is to provide a filtration system that can reduce the labor required for maintenance and inspection work of a filtration membrane unit of the filtration system or the like.

[0010] Means for solving problems

[0011] 14. The filter system of claim 13 wherein the filter elements are arranged in a manner that is symmetrical with respect to the filter element and wherein the filter elements are arranged in a symmetrical manner to form a filter element. The filter elements are arranged in a symmetrical manner to form a filter element. The filter elements are arranged in a symmetrical manner to form a filter element.

[0012] Effects of the Invention

[0013] According to the present invention, there is an excellent effect that the time and effort required for maintenance and inspection work of the filtration membrane unit can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1This is a diagram showing a schematic configuration of a water treatment facility using the filtration system according to the embodiment.

[0015] Figure 2 It is a perspective view showing a filtration membrane unit of the filtration system.

[0016] Figure 3 It is a perspective view showing a water collecting pipe installed in the filtering system.

[0017] Figure 4 It is a cross-sectional view showing the water collection pipe and the filtration membrane unit connected to the separate water collection channel.

[0018] Figure 5 This is a view showing the water collecting pipe and the filtration membrane unit from the axial direction of the main pipe portion of the water collecting pipe.

[0019] Figure 6 It is a perspective view showing a sealing plug.

[0020] Figure 7 It is a cross-sectional view showing the sealing plug and the water collecting pipe just before being inserted into the individual water collecting passage of the water collecting pipe.

[0021] Figure 8 It is a cross-sectional view showing the sealing plug and the water collecting pipe halfway inserted into the individual water collecting channel.

[0022] Fig. 9 It is a cross-sectional view showing a sealing plug and a water collecting pipe inserted into a separate water collecting channel.

[0023] Fig.10 It is a cross-sectional view for explaining the preparation operation for removal of the sealing plug.

[0024] Fig.11 It is a cross-sectional view showing the sealing plug and the water collecting pipe immediately after the removal preparation operation is performed.

[0025] Fig.12 It is a cross-sectional view showing the sealing plug and the water collecting pipe being pulled out in the middle.

[0026] Fig.13 It is a perspective view showing a filtration treatment device. DETAILED DESCRIPTION

[0027] Hereinafter, an embodiment of the liquid filter device to which the present invention is applied is described using each figure. In the embodiment, in order to facilitate the understanding of the description, the structure and elements other than the main part of the present invention are simplified or omitted. In addition, in each figure, the same reference numerals are marked on the same elements. It should be noted that the shapes, sizes, etc. of the elements shown in each figure are schematically represented and do not represent the actual shapes, sizes, etc.

[0028] Figure 1This is a diagram showing a schematic structure of a water treatment facility using a filtration system according to an embodiment. The water treatment facility includes a pre-treatment water tank 1, a filtration treatment water tank 2, a treatment water tank 3, a control device 4, a raw water pump 5, a first water level sensor 6, a raw water transfer pipe 7, a treatment water transfer pipe 8, a suction pump 9, a second water level sensor 11, a third water level sensor 12, etc. In addition, the water treatment facility includes a blower 13, an air supply pipe 14, a stand 15, a filtration system 20, a bubble generating device 30, etc.

[0029] Pre-treated water (raw water) W1 as liquid is stored in the pre-treated water tank 1. A first water level sensor composed of an ultrasonic sensor or the like provided in the pre-treated water tank 1 detects the water level (height of the water surface) of the pre-treated water W1 in the pre-treated water tank 1, and sends the detection result as a water level signal to the control device 4. The raw water pump 5 provided in the pre-treated water tank 1 sucks and discharges the pre-treated water W1 in the pre-treated water tank 1, and sends it to the filtration treatment water tank 2 through the raw water transfer pipe 7. As the raw water pump 5, a pump composed of a submersible pump is exemplified, but a pump composed of a surface pump may also be used.

[0030] The filtration treatment water tank 2 is a water tank made of reinforced concrete. A liquid filter device 50 is provided in the filtration treatment water tank 2. The liquid filter device 50 includes a stand 15, a filter system 20, and a bubble generator 30, and the whole is immersed in the pre-treatment water W1 in the filtration treatment water tank 2. The blower 13 discharges the air as gas sucked from the suction port to the air supply pipe 14 through the discharge port. The air discharged to the air supply pipe 14 is supplied to the bubble generator 30 of the liquid filter device 50. The third water level sensor 12 provided in the filtration treatment water tank 2 detects the water level of the pre-treatment water W1 in the filtration treatment water tank 2, and sends the detection result as a water level signal to the control device 4.

[0031] The suction pump 9 sucks and filters the pre-treated water W1 in the treated water tank 2 via the treated water transfer pipe 8 and the filter membrane to be described later provided in the filter system 20. The sucked pre-treated water W1 is filtered by the filter membrane to become treated water W2, and then is sent to the treated water tank 3 via the treated water transfer pipe 8. The second water level sensor 11 provided in the treated water tank 3 detects the water level of the treated water W2 in the treated water tank 3, and sends the detection result to the control device 4 as a water level signal.

[0032] It should be noted that a pump that generates suction force using water head pressure may be used instead of the suction pump 9. The means of suction is not particularly limited.

[0033] When the water level of the treatment water tank 3 has not reached the upper limit and the prescribed operation execution condition is satisfied, the control device 4 operates the suction pump 9 and the blower 13 to perform the filtration treatment of the pre-treatment water W1. However, even if the operation execution condition is satisfied, when the water level of the pre-treatment water W1 in the pre-treatment water tank 1 is below the lower limit, and when the water level of the pre-treatment water W1 in the filtration treatment water tank 2 is below the lower limit, the control device 4 also stops the execution of the filtration treatment. It should be noted that the function of the blower 13 will be described later.

[0034] Figure 2 : is a stereoscopic diagram showing a filter membrane unit 21. The filter membrane unit 21 includes a flat filter membrane 22, a cannula 16, and a sealing bracket 17. The filter membrane unit 21 is held by four retaining components 24 of a frame described later. In the liquid filtering device (50) of the embodiment, as the filter membrane 22, a filter membrane composed of a plate-like flat membrane is used, but the type of the filter membrane 22 is not limited to a flat membrane, and may also be other types such as a hollow fiber membrane. The material of the filter membrane 22 may be an organic material such as PVC (polyvinyl chloride) or PVDF (polyvinylidene fluoride), or may be a ceramic composed of one or more of alumina, cordierite, silicon carbide, and other metal oxides. In addition, the filter membrane 22 may also be a composite membrane formed by compounding an organic membrane and a ceramic membrane.

[0035] The filter membrane 22 includes a plurality of hollow spaces 22a extending in the vertical direction. These hollow spaces 22a are arranged at predetermined intervals in the short-side direction of the filter membrane 22, and the upper ends of the hollow spaces 22a are opened toward "upward".

[0036] A cannula 16 is installed at one end of the filter membrane 22 in the long side direction. The cannula 16 has an internal space connected to the hollow 22a of the filter membrane 22, and receives the treated water (W2) filtered by the filter membrane 22 into the internal space. One end of the cannula 16 in the long side direction becomes a discharge pipe 16a protruding from the end of the filter membrane 22. The discharge pipe 16a forms a discharge path on the inside and is inserted into a separate water collection path of the water collection pipe described later. Two O-rings 16b arranged in the axial direction of the insertion portion are installed on the outer peripheral surface of the discharge pipe 16a. The O-ring 16b is made of an elastic material such as rubber or resin.

[0037] When the suction pump ( Figure 1 9) when working, an attraction is generated on the surface of the filter membrane 22, and the pre-treated water ( Figure 1The treated water W1) is sucked into the hollow 22a through the countless micropores of the filter membrane 22. At this time, the untreated water W1 is filtered, and the pollutants in the untreated water W1 remain on the surface of the filter membrane 22. The treated water W2 sucked into the hollow 22a moves along the longitudinal direction in the hollow 22a, flows into the internal space of the cannula 16, and is discharged from the discharge pipe 16a of the cannula 16.

[0038] exist Figure 1 In the embodiment, the bubble generating device 30 provided below the filter system 20 releases bubbles toward the filter system 20 above. The released bubbles float in the untreated water W1, reach the filter membrane 22, are divided into a plurality of bubbles by the filter membrane 22, and then enter the area between the adjacent filter membranes 22. The bubbles floating in this area cause the untreated water W1 near the surface of the filter membrane 22 to be shaken violently, so that the contaminants attached to the surface of the filter membrane 22 are separated from the surface.

[0039] Figure 3 The figure is a three-dimensional diagram showing a water collecting pipe 90 mounted on the filtering system (20). The water collecting pipe 90 is formed by injection molding of a resin material such as polyethylene, polypropylene, polyvinyl chloride, etc., and comprises a cylindrical main pipe section 91, a flat box-shaped water collecting section 92, and two rubber sheets 95. The water collecting section 92 comprises a plurality of separate water collecting passages 93 arranged in the direction of the axis (L1) of the main pipe section 91 and connected to the main pipe section 91 in a direction orthogonal to the axis L1. As shown in the figure, the separate water collecting passages 93 are arranged on both sides of the water collecting section 92 with the center line L2 of the main pipe section 91 as the boundary.

[0040] Figure 4 1 is a cross-sectional view showing a water collecting pipe 90 and a filter membrane unit 21 connected to the separate water collecting channel 93. As shown in the figure, the discharge pipe 16a of the filter membrane unit 21 is inserted into the separate water collecting channel 93 of the water collecting pipe 90. Since an O-ring 16b is sandwiched between the outer peripheral surface of the inserted discharge pipe 16a and the inner peripheral surface of the separate water collecting channel 93, the airtightness between the two can be ensured.

[0041] The rubber sheet 95 of the water collecting pipe 90 is used to prevent the filtration membrane 22 of the filtration membrane unit 21 from directly colliding with the main pipe portion 91 of the water collecting pipe 90 when the filtration membrane unit 21 is installed relative to the water collecting pipe 90 .

[0042] Figure 5The drawing shows the water collecting pipe 90 and the filter membrane unit 21 from the axial direction of the main pipe section 91 of the water collecting pipe 90. The locking member 98 contacts the insertion pipe 16 of the filter membrane unit 21 installed in the water collecting pipe 90 from the side opposite to the water collecting pipe 90. The locking member 98 made of U-shaped steel is fixed to the frame described later by bolts, and contacts the insertion pipes 16 of all the filter membrane units 21 arranged in the axial direction while extending in the axial direction of the main pipe section 91 of the water collecting pipe 90. When the plurality of filter membrane units 21 are inserted into the individual water collecting passages (93) of the water collecting pipe 90, the axial movement of the discharge pipe (16a) is locked by the locking member 98. The filter membrane unit 21 thus locked prevents the discharge pipe (16a) not screwed to the individual water collecting passage (93) from falling out of the individual water collecting passage (93).

[0043] In this structure, when the drain pipes (16a) of the plurality of filter membrane units 21 are connected to the separate water collection passages (93) of the water collection pipe 90 individually, there is no need to perform the troublesome operation of rotating the threaded cup of the union joint to tighten the threads. The drain pipe (16a) can be simply inserted into the separate water collection passage (93). In addition, when the filter membrane units 21 are disassembled for maintenance and inspection, there is no need to perform the troublesome operation of repeatedly reversing the threaded cup of the union joint to loosen the threads. The drain pipe (16a) can be simply pulled out from the separate water collection passage (93). It should be noted that when the filtration system (20) is used with the damaged filter membrane unit 21 removed, the separate water collection passage (93) opened due to the disassembly is sealed by the sealing plug described later.

[0044] Figure 6 1 is a perspective view showing a sealing plug 100. The sealing plug 100 includes a hook portion 101, a flexible portion 102, a main body 103, and a handle 105 from the front end side to the rear end side. The hook portion 101 includes an inclined portion 101a that increases the radial dimension of the main body 103 from the axial front end side to the rear end side of the cylindrical main body 103, and a step portion 101b that sharply reduces the radial dimension at the rear end of the inclined portion 101a. The flexible portion 102 is an elongated shape formed integrally with the hook portion 101 and the main body 103, and can bend in the radial direction of the main body 103. The cylindrical main body 103 includes two O-rings 104 arranged in the axial direction on the outer peripheral surface of the front end side. The O-ring 104 is made of an elastic material such as resin or rubber. The handle 105 protrudes backward from the axial rear end surface of the main body 103 and extends in the radial direction of the main body 103.

[0045] Figure 7 1 is a cross-sectional view showing the sealing plug 100 and the water collecting pipe 90 immediately before being inserted into the individual water collecting passages 93 of the water collecting pipe 90 . Figure 8It is a cross-sectional view showing the sealing plug 100 and the water collecting pipe 90 which are halfway inserted into the individual water collecting channel 93 . Fig. 9 1 is a cross-sectional view showing the sealing plug 100 and the water collecting pipe 90 inserted into the individual water collecting channel 93 .

[0046] like Figure 7 As shown in FIG. 1 , the sealing plug 100 begins to be inserted into the separate water collection channel 93 with the hook portion 101 at the front. Figure 8 As shown, the sealing plug 100 inserted in the middle makes the hook portion 101 on the front end side slide and rub against the inner peripheral surface of the individual water collecting channel 93. With this sliding friction, the flexible portion 102 is bent toward the radial outside, so that the hook portion 101 can be inserted.

[0047] At the junction of the separate water collecting passage 93 of the water collecting pipe 90 and the inner space of the main pipe section 91, a hooked portion 91a for hooking the step portion 101b of the sealing plug 100 is arranged. Fig. 9 As shown, the sealing plug 100 is fully inserted into the separate water collection channel 93, so that the hook portion 101 on the front end side is located at the connecting portion between the separate water collection channel 93 and the internal space of the main pipe portion 91, thereby eliminating the sliding friction with the separate water collection channel 93. At this time, since the previously bent flexible portion 102 eliminates the bending, as shown in the figure, the step portion 101b of the hook portion 101 is hooked on the hooked portion 91a. Through this hooking, the sealing plug 100 can be prevented from falling off from the separate water collection channel 93. The O-ring 104 of the main body 103 is between the outer peripheral surface of the main body 103 and the inner peripheral surface of the separate water collection channel 93 to ensure the airtightness between the two.

[0048] Fig.10 It is a cross-sectional view for explaining the removal preparation operation of the sealing plug 100. Fig.11 It is a cross-sectional view showing the sealing plug 100 and the water collecting pipe 90 immediately after the removal preparation operation is performed. Fig.12 It is a cross-sectional view showing the sealing plug 100 and the water collecting pipe 90 in the process of being pulled out.

[0049] When the sealing plug 100 is pulled out from the separate water collecting channel 93, a pulling out preparation operation is performed before the pulling out. Fig.10 As shown in FIG. 1 , while holding the handle 105, the main body 103 is rotated about 90 degrees in the clockwise or counterclockwise direction. Fig.11 As shown in FIG. 1 , the hooking portion 101 of the sealing plug 100 is rotated to a position where the step portion (101b) is not hooked on the hooked portion 91a. Fig.12 As shown, the sealing plug 100 can be pulled out from the separate water collection channel 93 by pulling the sealing plug 100 .

[0050] In this structure, when the filtration system is operated with the damaged filtration membrane unit (21) removed from the water collecting pipe 90, the separate water collecting passage 93 opened by the removal is sealed by the sealing plug 100. When inserting and removing the sealing plug 100, as described above, the troublesome operation of rotating the screw cap multiple times is not required.

[0051] Therefore, according to the filtration system (20) of the embodiment, the time and effort required for maintenance and inspection work of the filtration membrane unit (21) can be reduced.

[0052] Fig.13 This is a perspective view showing a filtration treatment device 18 having a filtration system 20 according to an embodiment. The filtration treatment device 18 holds two filtration systems 20 in a vertically stacked state on a metal frame 19. The above-mentioned locking member (98) is fixed to the frame 19 by bolts.

[0053] The present invention is not limited to the above-described embodiments and examples, and a configuration different from the embodiments and examples may be adopted within the scope of the configuration to which the present invention can be applied. The present invention has unique effects in each of the modes described below.

[0054] [First method]

[0055] The first mode is a filtration system (filtration system 20), which includes a plurality of filtration membrane units (filtration membrane units 21), the filtration membrane units include filtration membranes (filtration membranes 22) and a discharge path for discharging filtrate obtained by the filtration membranes, and the filtration system includes a water collecting pipe (water collecting pipe 90), the water collecting pipe includes a main pipe section (main pipe section 91) and a plurality of separate water collecting paths (separate water collecting paths 93) arranged in the axial direction of the main pipe section and connected to the main pipe section, and the filtration system discharges the filtrate filtered by the filtration membranes of the plurality of filtration membrane units through the filtration membranes. The discharge path and the separate water collection path of the water collection pipe are collected into the main pipe part of the water collection pipe, and it is characterized in that the filtration system has a locking component (locking component 98), which locks the axial movement of the discharge path of each of the multiple filter membrane units, and the multiple filter membrane units are respectively provided with O-rings (O-rings 16b) made of elastic material on the outer peripheral surface of the discharge pipe (discharge pipe 16a) forming the discharge path, and when the discharge pipe is inserted into the separate water collection path, the axial movement of the discharge pipe is locked by the locking component.

[0056] According to this configuration, it is unnecessary to perform a screw rotation operation when attaching or detaching the filtration membrane unit to or from the water collecting pipe, and thus it is possible to reduce the labor required for maintenance and inspection work of the filtration membrane unit.

[0057] [Second Method]

[0058] The second mode is characterized in that, in a filtration system having the structure of the first mode, a sealing plug (sealing plug 100) is provided, which is inserted into the separate water collection path of the drainage pipe in which the filter membrane unit is not inserted among the multiple separate water collection paths in the water collection pipe to seal the separate water collection path.

[0059] According to this configuration, even when a part of the filtration membrane unit is removed from the filtration system due to damage or the like, the filtration system can be operated by sealing the individual water collection passage from which the filtration membrane unit is removed with the sealing plug.

[0060] [Third Method]

[0061] The third mode is a filtration system having the structure of the second mode, characterized in that the sealing plug comprises: a hook portion (hook portion 101) arranged at the axial front end portion, a cylindrical main body portion (main body 103) arranged at the axial center portion, a handle (handle 105) protruding rearward from the axial rear end surface of the main body portion and extending radially, and a flexible portion (flexible portion 102) located between the hook portion and the main body portion and capable of bending in the radial direction, the main body portion comprises an O-ring (O-ring 104) made of elastic material on the outer peripheral surface, the hook portion comprises: an inclined portion (inclined portion 101a) which increases the radial dimension of the main body portion as it increases from the axial front end side toward the rear end side and a step portion (step portion 101b) which sharply reduces the radial dimension at the rear end of the inclined portion, and the water collecting pipe comprises a hooked portion (hooked portion 91a) of the step portion for hooking the hook portion.

[0062] According to this configuration, it is unnecessary to perform a screw rotation operation when sealing the individual water collection passage from which the filtration membrane unit is removed, and thus it is possible to reduce the labor required for maintenance and inspection work of the filtration membrane unit.

[0063] This application claims the priority of Japanese patent application No. 2022-42256 filed on March 17, 2022, and cites all the contents described in the Japanese patent application.

[0064] Description of Reference Numerals

[0065] 20: Filtration system, 21: Filtration membrane unit, 16a: Drain pipe, 90: Water collecting pipe, 91: Main pipe, 91a: Hooked part, 92: Water collecting part, 93: Separate water collecting channel, 98: Locking component, 100: Sealing plug

Claims

1. A filtration system, comprising a plurality of filtration membrane units, each of which comprises a filtration membrane and a discharge path for discharging filtrate obtained from the filtration membrane, and a water collecting pipe, wherein the water collecting pipe comprises a main pipe and a plurality of separate water collecting paths arranged in the axial direction of the main pipe and connected to the main pipe, The filtration system collects the filtrate filtered by the filtration membranes of the plurality of filtration membrane units into the main pipe section of the water collection pipe via the discharge path and the separate water collection path of the water collection pipe, characterized in that: The filtration system includes a locking member for locking the axial movement of each of the plurality of filtration membrane units in the discharge path. The plurality of filter membrane units are each provided with an O-ring made of elastic material on the outer peripheral surface of a discharge pipe forming the discharge path, and the axial movement of the discharge pipe is locked by the locking component when the discharge pipe is inserted into the separate water collection path. The filtration system includes a sealing plug, which is inserted into an individual water collection channel in the water collection pipe, in which the discharge pipe of the filtration membrane unit is not inserted, among the plurality of individual water collection channels, to seal the individual water collection channel. The sealing plug comprises: a hook portion arranged at the front end portion in the axial direction, a cylindrical main body portion arranged at the central portion in the axial direction, a handle protruding rearward from the rear end surface in the axial direction of the main body portion and extending in the radial direction, and a flexible portion located between the hook portion and the main body portion and capable of bending in the radial direction. The main body has an O-ring made of elastic material on its outer peripheral surface. The hook portion includes an inclined portion that increases the radial dimension of the main body portion from the front end side toward the rear end side in the axial direction, and a stepped portion that sharply decreases the radial dimension at the rear end of the inclined portion. The water collecting pipe includes a hooked portion that is hooked on the step portion of the hooking portion.

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