Graded automatic purification, storage and utilization device for urban road rainfall flood resources

Abstract

The invention discloses an urban road rainfall flood resource grading automatic purification, storage and utilization device, and relates to the field of rainwater recycling. Comprising a filter box, a motor protection box and a battery protection box, a water inlet is formed in the top of the filter box and located below a drainage channel, an impurity filter screen is arranged at the position, located below the water inlet, in the filter box, a sediment collection mechanism is arranged below the impurity filter screen, and a first filter screen and a second filter screen are arranged in the filter box at intervals; the first filter screen is located on the side close to the motor protection box, the second filter screen is located on the side of the impurity filter screen, a cleaning mechanism is arranged on one side of the first filter screen, and a running water mechanism is arranged at the bottom of an inner cavity of the filter box. By arranging the cleaning mechanism, the service cycle of the whole filtering part is prolonged, by arranging the running water mechanism, the storage time of rainfall and flood resources in the filtering box is prolonged, and the cleanliness of the collected rainfall and flood resources is guaranteed within a certain time.

Description

Technical Field

[0001] The invention relates to the technical field of rainwater recycling and utilization, and in particular to a device for automatic graded purification, storage and utilization of urban road rainwater resources. Background Art

[0002] In recent years, due to the accelerated urbanization process, a large amount of land has been covered by impermeable asphalt and cement roads, which has led to a decrease in rainwater infiltration and an increase in water accumulation. In addition, due to the urban heat island effect, the rainfall has increased, further exacerbating the risk of urban waterlogging. In addition, the increase in extreme weather events and the lag of urban drainage systems have also become the main causes of urban waterlogging. Due to the necessity of social development, the rapid construction of urbanization is unstoppable. In addition, for the occurrence of extreme weather events, in addition to early warning and protection, there are few means that humans can solve. Then, in the end, the solution to the problem of urban waterlogging lies in the construction and innovation of urban drainage systems. And in this case, there is not only waterlogging in the city, but also water shortage. Therefore, the phenomenon of urban waterlogging needs to be considered from two directions. One is to establish a rainwater storage device that meets the standards of modern cities, and the other is to establish a rainwater resource filtration device and water supply device that meets the standards of non-drinking water for people's lives.

[0003] In the existing technology, the urban road rainwater collection system is an effective way to recycle and reuse water resources. At the same time, it can also solve the problem of flooding during heavy rains to a certain extent. The urban road rainwater collection system collects rainwater on urban roads according to demand, and processes the collected rainwater to meet the use standards. This requires the use of a filtering device to filter and process the collected rainwater.

[0004] After searching, the authorization announcement number is CN214005880U, and the name is a Chinese utility model patent for a rainwater collection device for urban roads. It discloses that the rainwater collection device for urban roads is provided with a water inlet pipe, a filter net, an irrigation water tank, a first water pump, an irrigation water pipe, a partition, a water purification filter device, a water purification tank, a second water pump and a water purification pipe, so that the collected rainwater can be filtered in two stages for different purposes, and most of the water can be used in time. However, the collection device does not have the function of clearing the filter net. After long-term use, the surface of the filter net is prone to blockage, which affects the filtering effect; in addition, the collection device does not have a water activating device, and the water stored in the water tank cannot be stored for a long time.

[0005] Through the search of the prior art, the main problems of the existing rainwater collection and filtration devices are summarized as follows:

[0006] 1. The existing rainwater collection and filtration devices have a relatively single function, and most of the devices require manual operation during use, and cannot be fully automated;

[0007] 2. In the existing rainwater collection and filtration device, impurities are easily left in the filter components. After long-term use, it is necessary to manually remove the impurities to ensure the cleanliness of the filter components and restore the service life of the entire filter components;

[0008] 3. The existing rainwater collection and filtration device is not equipped with a live water device. Each collected and filtered rainwater resources need to be provided in a timely manner to avoid the collected rainwater resources becoming "dead water" due to long-term storage in the storage box, thereby affecting the quality of the collected rainwater resources;

[0009] 4. The existing rainwater collection and filtration devices have a relatively complex design and shape, and the manufacturing process of the device is relatively complex, the construction is difficult, and the basic cost is high. Summary of the invention

[0010] The main purpose of the present invention is to provide a device for automatically purifying, storing and utilizing rainwater resources on urban roads in a hierarchical manner, so as to overcome the problems existing in the prior art.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0012] A device for automatic purification, storage and utilization of rainwater resources on urban roads in a graded manner, the device is located in a foundation below the road surface, and comprises a filter box, a motor protection box and a battery protection box, the motor protection box and the battery protection box are respectively located on both sides of the filter box, a water inlet is provided on the top of the filter box, the water inlet is located below a drainage channel, an impurity filter screen is provided at a position below the water inlet in the filter box, a sediment collection mechanism is provided below the impurity filter screen, a first filter screen and a second filter screen are provided at intervals in the filter box, the first filter screen is located on a side close to the motor protection box, the second filter screen is located on the side of the impurity filter screen, a cleaning mechanism is provided on one side of the first filter screen, a living water mechanism is provided at the bottom of the inner cavity of the filter box, and the living water mechanism is located between the first filter screen and the second filter screen.

[0013] Furthermore, the cleaning mechanism includes a brush, which is installed on a brush plate, and the brush plate is located on the side of the first filter screen. A first rotating motor is arranged in the motor protection box, and a rotating shaft is connected to the output end of the first rotating motor. The other end of the rotating shaft passes through the side wall of the motor protection box, the side wall of the filter box, the first filter screen and the brush, and is connected to the brush plate.

[0014] Furthermore, a concave box is provided on the side of the brush plate away from the first filter screen, a compression spring is provided between the concave box and the brush plate, guide blocks are provided at the upper and lower ends of the brush plate, and guide grooves matching the guide blocks 17 are provided at the upper and lower ends inside the concave box.

[0015] Furthermore, the living water mechanism includes a second rotating motor, a fan shaft and fan blades, the second rotating motor is arranged on the bottom wall of the inner cavity of the filter box, a motor protective layer is provided on the outer side of the second rotating motor, one end of the fan shaft is installed on the output end of the second rotating motor, and the other end passes through the motor protective layer and is connected to the fan blades.

[0016] Furthermore, the sediment collection mechanism includes a sediment collection box, a sediment seepage filter screen and a sediment filter screen, wherein the sediment filter screen is located at the upper portion of the sediment collection box, and the sediment seepage filter screen is located at the side of the sediment collection box close to the second filter screen.

[0017] Furthermore, a lifting mechanism is provided under the sediment collection box, and the lifting mechanism includes a servo motor, a telescopic shaft and a bottom plate. The servo motor is installed on the bottom wall of the inner cavity of the filter box, and a motor protective layer is provided on the outside of the servo motor. One end of the telescopic shaft is installed at the output end of the servo motor, and the other end passes through the motor protective layer and is connected to the bottom plate. The top end of the bottom plate is connected to the bottom end of the sediment collection box.

[0018] Furthermore, a storage battery is provided inside the battery protection box, and an electric energy transmission rod is connected to the storage battery. The other end of the electric energy transmission rod passes through the top wall of the battery protection box and extends above the road surface. The part of the electric energy transmission rod located above the road surface is connected to a solar panel, and a support rod is provided between the solar panel and the electric energy transmission rod.

[0019] Furthermore, it also includes a conveying mechanism, which includes a pump, a water inlet pipe and a drain pipe. The pump is installed at the bottom of the inner cavity of the motor protection box, one end of the water inlet pipe is connected to the pump, and the other end is connected to the filter box, one end of the drain pipe is connected to the pump, and the other end passes through the side wall of the motor protection box and extends to above the road surface, and a solenoid valve 2 is provided at the water outlet of the drain pipe.

[0020] Furthermore, the inner cavity of the filter box is provided with a pump protection filter at the inlet position of the water inlet pipe, and the filter box, the motor protection box and the battery protection box all adopt a rectangular box structure.

[0021] Furthermore, the portion of the drain pipe located in the drainage channel is connected to a flushing pipe, the outlet of the flushing pipe is located above the impurity filter, and a solenoid valve 1 is provided at the outlet of the flushing pipe.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] By setting up a cleaning mechanism, the service life of the entire filter component is extended, and human involvement is reduced in the process, the degree of automation is improved, the cost of manual operation is reduced, and it is more in line with the principle of smart city construction;

[0024] By setting up a living water mechanism, the storage time of rainwater resources in the filter box is extended, ensuring the cleanliness of the collected rainwater resources within a certain period of time. This also reduces the pressure of allocating rainwater resources and allows these rainwater resources to be allocated more efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the external structure of the present invention.

[0026] Figure 2 It is a schematic diagram of the internal structure of the present invention.

[0027] Figure 3 It is a cross-sectional view of the concave box structure of the present invention.

[0028] Figure 4 The present invention Figure 4 A partial enlarged view of point A in the figure.

[0029] Figure 5 It is a working flow diagram of the device of the present invention.

[0030] Description of the drawings: 1. foundation, 2. filter box, 3. drainage channel, 4. motor protection box, 5. first filter screen, 6. second filter screen, 7. first rotating motor, 8. rotating shaft, 9. concave box, 10. compression spring, 11. brush plate, 12. lifting mechanism, 121. servo motor, 122. telescopic shaft, 123. bottom plate, 13. sediment collection mechanism, 131. sediment collection box, 132. sediment seepage filter screen, 133. sediment filter screen, 14. conveying mechanism, 141. pump, 1 42. Water inlet pipe, 143. Drain pipe, 15. Activated water mechanism, 151. Second rotating motor, 152. Fan shaft, 153. Fan blades, 16. Motor protection layer, 17. Guide block, 18. Guide groove, 19. Pump protection filter, 20. Battery, 21. Power transmission rod, 22. Solar panel, 23. Solenoid valve 1, 24. Solenoid valve 2, 25. Support rod, 26. Impurity filter, 27. Impurity filter traction belt, 28. Battery protection box, 29. Flushing pipe. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0032] Combination Figures 1 to 5 The present embodiment provides a device for automatic purification, storage and utilization of rainwater resources in urban roads, which is located in a foundation 1 below the road surface, and includes a filter box 2, a motor protection box 4 and a battery protection box 28. The motor protection box 4 and the battery protection box 28 are respectively located on both sides of the filter box 2. A water inlet is provided on the top of the filter box 2, and the water inlet is located below the drainage channel 3. An impurity filter screen 26 is provided at a position below the water inlet in the filter box 2, and a sediment collection mechanism 13 is provided below the impurity filter screen 26. A first filter screen 5 and a second filter screen 6 are arranged in the filter box 2 at intervals, and the first filter screen 5 is located on a side close to the motor protection box 4, and the second filter screen 6 is located on the side of the impurity filter screen 26. A cleaning mechanism is provided on one side of the first filter screen 5, and a live water mechanism 15 is provided at the bottom of the inner cavity of the filter box 2, and the live water mechanism 15 is located between the first filter screen 5 and the second filter screen 6.

[0033] Preferably, the impurity filter screen 26 is connected to an impurity filter screen traction belt 27 .

[0034] Preferably, the filter box 2, the motor protection box 4 and the battery protection box 28 are all designed as rectangular boxes.

[0035] In this embodiment, the cleaning mechanism includes a brush, which is installed on a brush plate 11. The brush plate 11 is located on the side of the first filter 5. A first rotating motor 7 is arranged in the motor protection box 4. The output end of the first rotating motor 7 is connected to a rotating shaft 8. The other end of the rotating shaft 8 passes through the side wall of the motor protection box 4, the side wall of the filter box 2, the first filter 5 and the brush and is connected to the brush plate 11.

[0036] Preferably, a concave box 9 is provided on the side of the brush plate 11 away from the first filter screen 5, a compression spring 10 is provided between the concave box 9 and the brush plate 11, guide blocks 17 are provided at the upper and lower ends of the brush plate 11, and guide grooves 18 matching the guide blocks 17 are provided at the upper and lower ends inside the concave box 9.

[0037] In this embodiment, the living water mechanism 15 includes a second rotating motor 151, a fan shaft 152 and fan blades 153. The second rotating motor 151 is arranged on the bottom wall of the inner cavity of the filter box 2. A motor protective layer 16 is provided on the outer side of the second rotating motor 151. One end of the fan shaft 152 is installed on the output end of the second rotating motor 151, and the other end passes through the motor protective layer 16 and is connected to the fan blades 153.

[0038] In this embodiment, the sediment collection mechanism 13 includes a sediment collection box 131, a sediment seepage filter screen 132 and a sediment filter screen 133. The sediment filter screen 133 is located at the upper part of the sediment collection box 131, and the sediment seepage filter screen 132 is located at the side of the sediment collection box 131 close to the second filter screen 6.

[0039] Preferably, a lifting mechanism 12 is provided under the sediment collection box 131, and the lifting mechanism 12 includes a servo motor 121, a telescopic shaft 122 and a bottom plate 123. The servo motor 121 is installed on the bottom wall of the inner cavity of the filter box 2, and a motor protective layer 16 is provided on the outside of the servo motor 121. One end of the telescopic shaft 122 is installed at the output end of the servo motor 121, and the other end passes through the motor protective layer 16 and is connected to the bottom plate 123. The top of the bottom plate 123 is connected to the bottom end of the sediment collection box 131.

[0040] In this embodiment, a battery 20 is provided inside the battery protection box 28, and an electric energy transmission rod 21 is connected to the battery 20. The other end of the electric energy transmission rod 21 passes through the top wall of the battery protection box 28 and extends above the road surface. The part of the electric energy transmission rod 21 located above the road surface is connected to a solar panel 22, and a support rod 25 is provided between the solar panel 22 and the electric energy transmission rod 21.

[0041] In this embodiment, a conveying mechanism 14 is also included, and the conveying mechanism 14 includes a pump 141, a water inlet pipe 142 and a drain pipe 143. The pump 141 is installed at the bottom of the inner cavity of the motor protection box 4, one end of the water inlet pipe 142 is connected to the pump 141, and the other end is connected to the filter box 2. One end of the drain pipe 143 is connected to the pump 141, and the other end passes through the side wall of the motor protection box 4 and extends to above the road surface. A solenoid valve 24 is provided at the water outlet of the drain pipe 143.

[0042] Preferably, the inner cavity of the filter box 2 is provided with a pump protection filter 19 at the inlet position of the water inlet pipe 142 .

[0043] In this embodiment, the portion of the drain pipe 143 located in the drain channel 3 is connected to a flushing pipe 29 , the outlet of the flushing pipe 29 is located above the impurity filter 26 , and a solenoid valve 23 is provided at the outlet of the flushing pipe 29 .

[0044] Preferably, a controller is provided in the battery protection box 28, and the cleaning mechanism, the water-activating mechanism 15, the lifting mechanism 12, the battery 20, the pump 141, the solenoid valve 1 23 and the solenoid valve 2 24 are all electrically connected to the controller.

[0045] The main advantages and problems overcome by using the device of this embodiment are:

[0046] 1. The overall structure of the present invention is basically controlled by electrical signals, which reduces the participation of people in the entire device process, reduces the direct contact between people and rainwater resources, improves the automation level of the device and the working efficiency of the entire device, and to a certain extent also conforms to the characteristics of smart city construction in the new era;

[0047] 2. The present invention is designed with a cleaning mechanism, which can clean the first filter 5, thereby ensuring the cleanliness of the filter component and extending the service life of the filter component in the entire device process. At the same time, the existence of the cleaning mechanism greatly promotes the efficiency of the entire device process, and to a certain extent avoids the decrease in the efficiency of the entire device caused by the clogging of the filter component due to impurities;

[0048] 3. The present invention is equipped with a live water mechanism 15. When rainwater resources are stored in a dark environment for a long time and are not circulated, the rainwater resources will become dead water, which will reduce the efficiency of the entire device. In order to extend the storage time of rainwater resources in the storage tank, a live water mechanism can be installed in the entire device. The live water mechanism can not only extend the storage time of rainwater resources in the water storage tank, but also make sufficient allocation in the reasonable distribution of rainwater resources;

[0049] 4. The present invention adds a solar panel 22 and an adapted energy storage device to provide energy for the entire system. Due to the presence of the solar panel, the energy used by the entire system is clean and pollution-free. The presence of the solar panel also reduces energy consumption, greatly improving the universality and cleanliness of the system, making the entire system more in line with the construction of a clean city;

[0050] 5. The present invention adopts a graded filtering system, which can achieve graded filtering for rainwater resources entering the water inlet. Large impurities such as leaves can be filtered by the impurity filter 26, and silt can be filtered by the silt filter 133 and collected in the silt collection box 131. Due to the presence of the impurity filter and the silt filter, the use time of the first filter 5 and the second filter 6 in the filter box is greatly extended, and the use efficiency is improved;

[0051] 6. The present invention designs a sediment collection mechanism 13. Through the design of the mechanism, sediment can be deposited, which can prevent sediment from entering the filter box to a certain extent. In addition, it can also prevent the entire device from being used for a long time and a large amount of sediment from accumulating in the filter box, which requires cleaning of the entire structure. Due to the existence of the mechanism, the use time of the device can be extended, and after a period of use, the sediment can be manually removed to improve the use efficiency of the device;

[0052] 7. The present invention adopts a rectangular box design, and each component in the device adopts the simplest design and can meet the design target requirements. In addition, due to the rectangular design, it is easy to operate during installation and has low labor costs;

[0053] 8. The filter box 2 of the present invention adopts a four-layer filter screen design. The second layer of filter screen 6 performs the initial impurity treatment on the rainwater resources entering the filter box. The first layer of filter screen 5 filters the rainwater resources again and further treats the impurities. Finally, the two layers of pump protection filter screens 19 perform the final treatment on the impurities to meet the requirements.

[0054] 9. The present invention designs a pump protection filter, which can, firstly, further filter the rainwater resources before entering the pump, and secondly, can also protect the pump;

[0055] 10. The present invention installs a flushing pipe 29 on the drain pipe. Due to the setting of the lifting mechanism 12, the impurity filter 26 can be pushed to the entrance of the water inlet. In this way, the flushing pipe can flush the impurities on the impurity filter to ensure the cleanliness of the impurity filter, thereby ensuring that the impurity filter can be used for a long time and improving the effective efficiency of the entire device;

[0056] 11. The present invention installs electromagnetic valves on the drainage pipe and the flushing pipe. When the lifting mechanism starts to operate, the electromagnetic valve 1 23 on the flushing pipe is opened, and the electromagnetic valve 2 24 on the drainage pipe is closed to perform the flushing work; when draining, the electromagnetic valve 2 24 on the drainage pipe is opened, and the electromagnetic valve 1 23 on the flushing pipe is closed to perform the drainage work. The existence of the two sets of electromagnetic valves effectively improves the efficient operation of the entire work process;

[0057] 12. The water-activating mechanism used in the present invention is a fan device, which disturbs the rainwater resources through the action of the fan device, thereby ensuring the storage of the overall oxygen content of the rainwater resources and preventing the formation of "dead water";

[0058] 13. Due to the function of solar panels, the present invention converts solar energy into electrical energy, reduces energy consumption, and reduces the use cost of the entire device;

[0059] 14. This patent solves the problem we raised through the efficient combination of multiple mechanisms, achieves the expected results, and better meets the various assumed rainwater resource collection and filtration situations.

[0060] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A device for automatically purifying, storing and utilizing rainwater resources on urban roads in a hierarchical manner, the device being located in a foundation (1) below the road surface, characterized in that: The invention comprises a filter box (2), a motor protection box (4) and a battery protection box (28), wherein the motor protection box (4) and the battery protection box (28) are respectively located on both sides of the filter box (2), a water inlet is provided on the top of the filter box (2), and the water inlet is located below the drainage channel (3), an impurity filter screen (26) is provided in the filter box (2) at a position below the water inlet, and a sediment collection mechanism (13) is provided below the impurity filter screen (26), a first filter screen (5) and a second filter screen (6) are arranged in the filter box (2) at intervals, the first filter screen (5) is located on a side close to the motor protection box (4), the second filter screen (6) is located on the side of the impurity filter screen (26), a cleaning mechanism is provided on one side of the first filter screen (5), and a live water mechanism (15) is provided at the bottom of the inner cavity of the filter box (2), and the live water mechanism (15) is located between the first filter screen (5) and the second filter screen (6).

2. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 1, characterized in that: The cleaning mechanism comprises a brush, which is mounted on a brush plate (11). The brush plate (11) is located on the side of the first filter screen (5). A first rotating motor (7) is arranged in the motor protection box (4). The output end of the first rotating motor (7) is connected to a rotating shaft (8). The other end of the rotating shaft (8) passes through the side wall of the motor protection box (4), the side wall of the filter box (2), the first filter screen (5) and the brush, and is connected to the brush plate (11).

3. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 2, characterized in that: A concave box (9) is provided on the side of the brush plate (11) away from the first filter screen (5), a compression spring (10) is provided between the concave box (9) and the brush plate (11), guide blocks (17) are provided at the upper and lower ends of the brush plate (11), and guide grooves (18) matching the guide blocks (17) are provided at the upper and lower ends of the interior of the concave box (9).

4. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 1, characterized in that: The water activation mechanism (15) comprises a second rotating motor (151), a fan shaft (152) and fan blades (153); the second rotating motor (151) is arranged on the bottom wall of the inner cavity of the filter box (2); a motor protection layer (16) is arranged on the outer side of the second rotating motor (151); one end of the fan shaft (152) is installed on the output end of the second rotating motor (151), and the other end passes through the motor protection layer (16) and is connected to the fan blades (153).

5. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 1, characterized in that: The sediment collection mechanism (13) comprises a sediment collection box (131), a sediment seepage filter screen (132) and a sediment filter screen (133); the sediment filter screen (133) is located at the upper portion of the sediment collection box (131); and the sediment seepage filter screen (132) is located at the side of the sediment collection box (131) close to the second filter screen (6).

6. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 5, characterized in that: A lifting mechanism (12) is provided below the sediment collection box (131), the lifting mechanism (12) comprising a servo motor (121), a telescopic shaft (122) and a bottom plate (123), the servo motor (121) being mounted on the bottom wall of the inner cavity of the filter box (2), a motor protection layer (16) being provided on the outer side of the servo motor (121), one end of the telescopic shaft (122) being mounted on the output end of the servo motor (121), and the other end of the telescopic shaft (122) passing through the motor protection layer (16) and connected to the bottom plate (123), the top end of the bottom plate (123) being connected to the bottom end of the sediment collection box (131).

7. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 1, characterized in that: A storage battery (20) is arranged inside the battery protection box (28), and an electric energy transmission rod (21) is connected to the storage battery (20). The other end of the electric energy transmission rod (21) passes through the top wall of the battery protection box (28) and extends above the road surface. The part of the electric energy transmission rod (21) located above the road surface is connected to a solar panel (22), and a support rod (25) is arranged between the solar panel (22) and the electric energy transmission rod (21).

8. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 1, characterized in that: It also includes a conveying mechanism (14), the conveying mechanism (14) includes a pump (141), a water inlet pipe (142) and a drain pipe (143), the pump (141) is installed at the bottom of the inner cavity of the motor protection box (4), one end of the water inlet pipe (142) is connected to the pump (141), and the other end is connected to the filter box (2), one end of the drain pipe (143) is connected to the pump (141), and the other end passes through the side wall of the motor protection box (4) and extends to the top of the road surface, and a solenoid valve 2 (24) is provided at the water outlet of the drain pipe (143).

9. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 8, characterized in that: The inner cavity of the filter box (2) is located at the inlet position of the water inlet pipe (142) and is provided with a pump protection filter screen (19). The filter box (2), the motor protection box (4) and the battery protection box (28) all adopt a rectangular box structure.

10. The device for automatic purification, storage and utilization of rainwater resources in urban roads according to claim 8, characterized in that: The portion of the drainage pipe (143) located in the drainage channel (3) is connected to a flushing pipe (29), the outlet of the flushing pipe (29) is located above the impurity filter (26), and a solenoid valve (23) is provided at the outlet of the flushing pipe (29).

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