Permanent magnet synchronous motor heat dissipation structure suitable for high-speed operation environment
By creating a composite heat dissipation path that combines eddies and directional airflow under the drive of a permanent magnet motor, the problems of heat concentration and bubble formation in high-speed permanent magnet synchronous motors are solved, achieving a more efficient heat dissipation effect.
Patent Information
- Application Number
- CN202510987600.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-17
- Publication Date
- 2025-10-17
AI Technical Summary
High-speed permanent magnet synchronous motors are prone to heat concentration, bubble formation, and localized heat dissipation failure during the heat dissipation process, resulting in a decrease in heat dissipation efficiency.
Driven by a permanent magnet motor, the blades create vortexes that agitate the water flow, breaking up bubbles and distributing the water temperature evenly. At the same time, the fan blades create directional airflow to forcibly remove heat. Combined with air pressure pulse waves, this enhances the shedding of impurities and the absorption of heat, forming a composite heat dissipation path.
It improves heat dissipation efficiency and stability, avoids problems such as local overheating and uneven cooling, and improves heat transfer efficiency.
Smart Images
Figure CN120811029A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a heat dissipation structure of a permanent magnet synchronous motor suitable for a high-speed operation environment. BACKGROUND
[0002] The permanent magnet synchronous motor (PMSM) is widely applied to the fields of new energy vehicles, aerospace, industrial high-speed spindles and the like due to high power density, high efficiency and high reliability. With the development of technology, the rotating speed of the motor is continuously increased (for example, the rotating speed of a new energy vehicle driving motor has exceeded 20,000 rpm, and the rotating speed of an industrial high-speed motor can reach 100,000 rpm), but the heat management problem caused by high-speed operation becomes a core bottleneck restricting the performance and service life of the motor.
[0003] When the traditional heat dissipation pipe and the heat conduction box dissipate heat of the motor, the heat is concentrated in a part due to the heat formation area, and air bubbles are generated in the heat concentration area, so that heat stratification is easily formed, local heat dissipation failure is caused, and the heat dissipation efficiency is affected. SUMMARY
[0004] When the permanent magnet motor is used, the permanent magnet motor drives two groups of blades to rotate, and the water source is formed into a vortex in the water storage tank during the rotation of the two groups of blades, so that the vortex breaks the air bubbles generated due to local overheating by forcibly stirring the water flow, the shear force of the vortex can destroy the adhesion of the air bubbles on the surface of the water storage tank, the heat insulation effect of the air film is avoided to reduce the heat dissipation efficiency, and the water temperature distribution in the water tank is more uniform through the stirring and mixing of the vortex, local overheating is avoided, the overall heat dissipation stability is improved, and the uneven water flow speed or uneven heat dissipation in the water tank is avoided to cause water temperature stratification.
[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme: a heat dissipation structure of a permanent magnet synchronous motor suitable for a high-speed operation environment, which comprises a water storage tank located outside a rotating shaft, a belt pulley A mounted outside the rotating shaft is arranged in the water storage tank, two groups of blades are connected to one side of the belt pulley A, a belt pulley B is rotatably arranged on the inner wall of the water storage tank, and a screw flight is connected to one end of the belt pulley B. One side of the water storage tank is connected with two groups of conveying pipes, two groups of the conveying pipes are connected with sealing grooves outside, a movable shaft is rotatably arranged in the sealing groove, a fan blade is connected to one end of the movable shaft, a guide pipe A is connected to the outside of the sealing groove, a reciprocating screw rod is rotatably arranged in the guide pipe A, and a storage groove is communicated with one end of the guide pipe A. One side of the storage groove is communicated with a guide pipe B, a push rod is movably connected in the guide pipe B, and the guide pipe B is communicated with the conveying pipe outside.
[0006] Preferably, the water storage tank is provided with a rotating shaft, the pulley A is internally sleeved with two groups of belts, and the other ends of the two groups of belts are sleeved with pulley B.
[0007] Preferably, the auger piece is located inside the conveying pipe, one end of the two groups of conveying pipes is connected with the heat exchange tank, and the conveying path of the conveying pipe is inclined.
[0008] Preferably, the movable shaft is movably connected inside the sealing groove, the movable shaft is connected with a plurality of baffles outside, the plurality of baffles extend into the conveying pipe, one end of the connecting rod is connected with the connecting rod, and the connecting rod extends through the heat exchange tank to the outside and is connected with the fan blade.
[0009] Preferably, the other end of the movable shaft is connected with the reciprocating screw rod, the reciprocating screw rod extends through the heat exchange tank to the outside, the guide pipe A is internally provided with a piston, and the piston is connected with the ball nut pair of the reciprocating screw rod.
[0010] Preferably, one end of the guide pipe A is connected with the connecting pipe A, the other end of the connecting pipe A is connected with the storage tank, the storage tank is connected with the connecting pipe B outside, and the storage tank is provided with an air pressure valve at the connecting position of the connecting pipe B.
[0011] Preferably, the other end of the connecting pipe B is connected with the guide pipe B, one end of the push rod fixedly connected with the spring inside the guide pipe B, and the other end of the spring is connected with the inner wall of the guide pipe B.
[0012] Preferably, the guide pipe B is connected with a branch pipe outside, the branch pipe is located on the side of the guide pipe B close to the output end, and the other end of the branch pipe is connected with the inside of the conveying pipe.
[0013] Preferably, the heat exchange tank is connected with the connecting pipe C on one side, the other end of the connecting pipe C is connected with the water storage tank, and the connecting pipe C is connected with the pump on one side.
[0014] Compared with the prior art, the beneficial effects of the present application are: When the permanent magnet motor is used, the permanent magnet motor drives the pulley A to rotate, thereby synchronously driving the two groups of blades to rotate, and the water source inside the water storage tank forms a vortex, so that the vortex forcibly stirs the water flow, breaks the bubbles generated by local overheating, the shear force of the vortex can destroy the adhesion of the bubbles on the surface of the water storage tank, avoid the gas film heat insulation effect to reduce the heat dissipation efficiency, and through the stirring and mixing of the vortex, the water temperature distribution in the water tank is more uniform, local overheating is avoided, the overall heat dissipation stability is improved, and uneven water flow velocity or uneven heat dissipation is avoided, so that the water temperature in the water tank is stratified.
[0015] The application drives the fan blades to rotate synchronously after the water source enters the inside of the conveying pipe, and when the fan blades rotate, a certain airflow is generated, so that the airflow emitted by the fan blades promotes the flow of the airflow around the permanent magnet motor, and because the fan blades are obliquely arranged, the heat emitted by the permanent magnet motor is further promoted to flow to the outer wall of the water storage tank, so that the rotation of the fan blades forms directional airflow, forcibly taking away the heat on the surface of the outer shell of the permanent magnet motor, compared with natural convection, the heat exchange coefficient of forced convection can improve the heat dissipation efficiency of the permanent magnet motor, and the heat in the hot gas is first transmitted to the outer wall of the water storage tank through heat conduction, and then further takes away the heat through the flow and vortex of the water in the water storage tank, forming a composite heat dissipation path.
[0016] After the air pressure valve is opened, the application knocks the outer wall of the conveying pipe, so that the impurities attached to the inner wall of the conveying pipe fall off, and after the air pressure enters the branch pipe inside, the air pressure enters the inside of the conveying pipe through the branch pipe, so that a certain pushing force is applied to the water source inside the conveying pipe, so that the instantaneous speed of the water source inside the conveying pipe increases, so that the air pressure forms a pulse wave after entering the conveying pipe, and the water hammer effect is formed together with the instantaneous accelerated water flow, so that the impurities attached to the inner wall of the conveying pipe are better detached from the inner wall of the conveying pipe, and the conveying pipe can better absorb the heat of the permanent magnet motor vertically upward, preventing the impurities from causing slow heat transfer efficiency. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is one of the overall structure schematic diagram of the application; Figure 2 It is the second overall structure schematic diagram of the application; Figure 3 It is the internal structure diagram of the water storage tank of the application; Figure 4 It is a partial structure diagram of the application; Figure 5 It is a partial structure cross-sectional view of the application; Figure 6 It is a partial structure cross-sectional view of the application; Figure 7 It is the Figure 5 Structure enlarged view of A in the application; Figure 8 It is the Figure 6 Structure enlarged view of B in the application.
[0018] In the figure: 1, permanent magnet motor; 2, rotating shaft; 3, water storage tank; 4, pulley A; 5, blade; 6, belt; 7, pulley B; 8, auger piece; 9, conveying pipe; 10, heat exchange tank; 11, sealing groove; 12, baffle; 13, movable shaft; 14, connecting rod; 15, fan blade; 16, reciprocating screw rod; 17, piston; 18, guide pipe A; 19, connecting pipe A; 20, storage tank; 21, connecting pipe B; 22, guide pipe B; 23, push rod; 24, spring; 25, branch pipe; 26, pump; 27, connecting pipe C. DETAILED DESCRIPTION
[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.
[0020] Reference Figures 1-8 , the present application provides a heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment, comprising a water storage tank 3 located outside the rotating shaft 2, the water storage tank 3 is provided with a pulley A 4 installed outside the rotating shaft 2, one side of the pulley A 4 is connected with two groups of blades 5, the inner wall of the water storage tank 3 rotates with a pulley B 7, one end of the pulley B 7 is connected with an auger piece 8; One side of the water storage tank 3 is connected with two groups of conveying pipes 9, the outer side of the two groups of conveying pipes 9 is connected with a sealing groove 11, the sealing groove 11 rotates with a movable shaft 13 inside, one end of the movable shaft 13 is connected with a fan blade 15, the outer side of the sealing groove 11 is connected with a guide pipe A 18, the guide pipe A 18 rotates with a reciprocating screw rod 16 inside, one end of the guide pipe A 18 is communicated with a storage tank 20; One side of the storage tank 20 is communicated with a guide pipe B 22, the guide pipe B 22 is movably connected with a push rod 23 inside, the outer side of the guide pipe B 22 is communicated with the conveying pipe 9.
[0021] In an optional embodiment, the water storage tank 3 is arranged through the rotating shaft 2, the pulley A 4 is sleeved with two groups of belts 6, and the other ends of the two groups of belts 6 are sleeved with the pulley B 7. When the permanent magnet motor 1 is used, the permanent magnet motor 1 drives the rotating shaft 2 to rotate. When the rotating shaft 2 rotates, the heat emitted by the rotating shaft 2 is conducted to the outer wall of the water storage tank 3, so that the heat emitted by the permanent magnet motor 1 is transported to the inner wall of the water storage tank 3. When the rotating shaft 2 rotates, the pulley A 4 is driven to rotate synchronously. When the pulley A 4 rotates, the two groups of pulley B 7 are driven to rotate synchronously by the belts 6. When the pulley A 4 rotates, the two groups of blades 5 are driven to rotate synchronously. When the two groups of blades 5 rotate, the water source inside the water storage tank 3 forms a vortex, so that the vortex breaks the bubbles generated by local overheating by forced stirring of the water flow. The shear force of the vortex can destroy the adhesion of the bubbles on the surface of the water storage tank 3, avoid the gas film heat insulation effect to reduce the heat dissipation efficiency, and through the stirring and mixing of the vortex, the water temperature distribution in the water tank is more uniform, the local overheating is avoided, the overall heat dissipation stability is improved, and the uneven water flow velocity or uneven heat dissipation in the water tank is avoided, which causes the water temperature stratification in the water tank.
[0022] In an optional embodiment, the auger piece 8 is arranged inside the conveying pipe 9, and the two groups of conveying pipes 9 are connected with the heat exchange tank 10 at one end. The conveying path of the conveying pipe 9 is inclined. As described above, when the pulley B 7 rotates, the auger piece 8 rotates in the conveying pipe 9. When the conveying pipe 9 rotates, the water source in the water storage tank 3 is evenly transported into the conveying pipe 9, so that the water source in the water storage tank 3 is prevented from flowing unstably into the conveying pipe 9 due to the action of the vortex.
[0023] In an optional embodiment, the movable shaft 13 is movably connected inside the sealing groove 11, and a plurality of baffles 12 are connected outside the movable shaft 13 and extend into the conveying pipe 9, and one end of the movable shaft 13 is connected with a connecting rod 14 which extends through the heat exchange groove 10 to the outside and is connected with the fan blade 15. When the water source enters the conveying pipe 9, the water flow is accelerated by the downward force due to the inclined conveying pipe 9, so that the plurality of baffles 12 are driven to rotate by the scouring force of the water flow, and the movable shaft 13 is synchronously rotated, and the connecting rod 14 is synchronously rotated, and the fan blade 15 is synchronously rotated, and the airflow is generated by the rotation of the fan blade 15, so that the airflow around the fan blade 15 is pushed by the airflow generated by the fan blade 15, and the heat dissipated by the permanent magnet motor 1 is promoted to flow to the outer wall of the water storage tank 3 due to the inclined arrangement of the fan blade 15, so that the fan blade 15 forms a directional airflow to forcibly remove the heat on the surface of the outer shell of the permanent magnet motor 1. Compared with natural convection, the heat exchange coefficient of forced convection can improve the heat dissipation efficiency of the permanent magnet motor 1, and the heat in the hot air is first transferred to the outer wall of the water storage tank 3 through heat conduction, and then further removed by the flow and vortex of the water in the water storage tank 3, forming a composite heat dissipation path.
[0024] In an optional embodiment, the other end of the movable shaft 13 is connected with the reciprocating screw rod 16 which extends through the heat exchange groove 10 to the outside, and the piston 17 is arranged inside the guide pipe A 18, and the piston 17 is connected with the ball nut pair of the reciprocating screw rod 16. When the movable shaft 13 rotates, the reciprocating screw rod 16 is synchronously rotated, and the piston 17 is driven to reciprocate in the guide pipe A 18, and the gas pressure at the rear end of the guide pipe A 18 is continuously delivered.
[0025] In an optional embodiment, the guide pipe A 18 is connected with the connecting pipe A 19 at one end, and the other end of the connecting pipe A 19 is connected with the storage tank 20, and the connecting pipe B 21 is connected outside the storage tank 20, and the gas pressure valve is arranged at the connection between the storage tank 20 and the connecting pipe B 21. The gas pressure at the rear end of the guide pipe A 18 is delivered to the inside of the storage tank 20 through the connecting pipe A 19, and when the amount of gas pressure in the storage tank 20 reaches a certain value, the gas pressure valve connected with the connecting pipe B 21 is opened, so that the gas pressure stored in the storage tank 20 rapidly enters the inside of the connecting pipe B 21.
[0026] In an optional embodiment, the other end of the connecting pipe B21 is connected with the guide pipe B22, the end of the push rod 23 inside the guide pipe B22 is fixedly connected with the spring 24, the other end of the spring 24 is connected with the inner wall of the guide pipe B22, after the air pressure valve is opened, the air pressure will quickly enter the inside of the guide pipe B22 through the connecting pipe B21, after the air pressure enters the inside of the guide pipe B22, the push rod 23 will be quickly pushed out, after the push rod 23 is pushed out, it will contact the outer wall of the conveying pipe 9, due to the quick pushing of the push rod 23, the push rod 23 will knock the outer wall of the conveying pipe 9, so that the impurities attached to the inner wall of the conveying pipe 9 fall off, after the air pressure in the storage tank 20 gradually leaks out, the push rod 23 will be gradually reset by the force of the spring 24.
[0027] In an optional embodiment, the outer side of the guide pipe B22 is connected with the branch pipe 25, the branch pipe 25 is located on the side of the guide pipe B22 close to the output end, the other end of the branch pipe 25 is connected with the inside of the conveying pipe 9, after the push rod 23 is pushed out, the excess air pressure will enter the inside of the branch pipe 25, after the air pressure enters the inside of the branch pipe 25, the air pressure will enter the inside of the conveying pipe 9 through the branch pipe 25, so that part of the air pressure enters the inside of the water tank 3, and the other part of the air pressure enters the inside of the conveying pipe 9, when the air pressure enters the inside of the conveying pipe 9, it will exert a certain pushing force on the water source in the inside of the conveying pipe 9, so that the instantaneous speed of the water source in the inside of the conveying pipe 9 increases, so that the air pressure entering the conveying pipe 9 forms a pulse wave, and the water hammer effect is formed together with the instantaneous accelerated water flow, which exerts a greater force on the impurities attached to the inner wall of the conveying pipe 9, so that the impurities are better detached from the inner wall of the conveying pipe 9, and at the same time, it also ensures that the conveying pipe 9 can better absorb the heat of the permanent magnet motor 1 vertically upward, preventing too many impurities from causing slow heat transfer efficiency.
[0028] In an optional embodiment, the side of the heat exchange tank 10 is connected with the connecting pipe C27, the other end of the connecting pipe C27 is connected with the water tank 3, and the side of the connecting pipe C27 is connected with the pump 26, after the water source in the inside of the water tank 3 enters the inside of the heat exchange tank 10, the pump 26 will deliver the water source to the inside of the water tank 3 again through the connecting pipe C27.
[0029] Working principle: when the permanent magnet motor 1 is used, the permanent magnet motor 1 will drive the rotating shaft 2 to rotate, and the heat generated by the rotating shaft 2 will be conducted to the outer wall of the water tank 3, so that the heat generated by the permanent magnet motor 1 is transmitted to the inner wall of the water tank 3, while the rotating shaft 2 is rotating, it will synchronously drive the belt pulley A4 to rotate, when the belt pulley A4 rotates, it will drive the two sets of belt pulleys B7 to rotate synchronously through the belt 6, and when the belt pulley A4 rotates, it will synchronously drive the two sets of blades 5 to rotate, when the two sets of blades 5 rotate, they will form a vortex in the water tank 3. When the belt pulley B7 rotates, it will drive the auger piece 8 to rotate inside the conveying pipe 9. When the conveying pipe 9 rotates, it will uniformly convey the water source inside the water storage tank 3 into the conveying pipe 9. After the water source enters the conveying pipe 9, the water flow will accelerate due to the downward force because the conveying pipe 9 is inclined. When the water source flows into the conveying pipe 9, it will drive the multiple baffles 12 to rotate through the scouring force of the water flow. When the baffles 12 rotate, they will drive the movable shaft 13 to rotate synchronously. When the movable shaft 13 rotates, it will drive the connecting rod 14 to rotate. When the connecting rod 14 rotates, it will drive the fan blade 15 to rotate synchronously. When the fan blade 15 rotates, it will generate a certain airflow, and the airflow emitted by the fan blade 15 will push the airflow around the permanent magnet motor 1 to flow. When the movable shaft 13 rotates, it will drive the reciprocating screw rod 16 to rotate. When the reciprocating screw rod 16 rotates, it will drive the piston 17 to reciprocate inside the guide pipe A18. When the piston 17 reciprocates, it will continuously deliver air pressure to the rear end of the guide pipe A18. The air pressure entering the rear end of the guide pipe A18 will be delivered to the storage tank 20 inside the connecting pipe A19. When the air pressure in the storage tank 20 reaches a certain value, the air pressure valve connected to the connecting pipe B21 will be opened, allowing the air pressure stored in the storage tank 20 to quickly enter the connecting pipe B21. After the air pressure valve is opened, the air pressure will quickly enter the guide pipe B22 through the connecting pipe B21. After the air pressure enters the guide pipe B22, it will quickly push the push rod 23 outward. After the push rod 23 is pushed outward, it will contact the outer wall of the conveying pipe 9. Due to the rapid pushing of the push rod 23, the push rod 23 will produce knocking on the outer wall of the conveying pipe 9. After the push rod 23 is pushed outward, the excess air pressure will enter the branch pipe 25. After the air pressure enters the branch pipe 25, it will enter the conveying pipe 9 through the branch pipe 25, so that part of the air pressure enters the water storage tank 3 and the other part enters the conveying pipe 9. When the air pressure enters the conveying pipe 9, it will exert a certain pushing force on the water source inside the conveying pipe 9, thereby increasing the instantaneous speed of the water source inside the conveying pipe 9.
[0030] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A permanent magnet synchronous motor heat dissipation structure suitable for high-speed operation environment, comprising a water storage tank (3) located outside a rotating shaft (2), characterized in that: A pulley A (4) is provided inside the water storage tank (3) and is mounted on the outside of the rotating shaft (2). Two sets of blades (5) are connected to one side of the pulley A (4). A pulley B (7) rotates on the inner wall of the water storage tank (3). One end of the pulley B (7) is connected to a screw blade (8). One side of the water storage tank (3) is connected to two groups of delivery pipes (9), the outer sides of the two groups of delivery pipes (9) are connected to sealing grooves (11), a movable shaft (13) rotates inside the sealing grooves (11), one end of the movable shaft (13) is connected to a fan blade (15), the outer side of the sealing grooves (11) is connected to a guide tube A (18), a reciprocating screw rod (16) rotates inside the guide tube A (18), and one end of the guide tube A (18) is connected to a storage tank (20); One side of the storage tank (20) is connected to a guide pipe B (22), the interior of the guide pipe B (22) is movably connected to a push rod (23), and the outside of the guide pipe B (22) is connected to the delivery pipe (9).
2. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 1, characterized in that: The water storage tank (3) and the rotating shaft (2) are arranged to penetrate each other, and two groups of belts (6) are sleeved inside the pulley A (4), and the other ends of the two groups of belts (6) are sleeved with pulleys B (7).
3. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 1, characterized in that: The auger piece (8) is located inside the delivery pipe (9), one end of the two groups of delivery pipes (9) is connected to a heat exchange tank (10), and the delivery path of the delivery pipe (9) is an inclined surface.
4. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 3, characterized in that: The sealing groove (11) is movably connected to a movable shaft (13) inside, and multiple groups of baffles (12) are connected to the outside of the movable shaft (13). The multiple groups of baffles (12) extend into the inside of the delivery pipe (9). One end is connected to a connecting rod (14), and the connecting rod (14) passes through the heat exchange groove (10) and extends to the outside to be connected to the fan blade (15).
5. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 1, characterized in that: The other end of the movable shaft (13) is connected to the reciprocating screw (16), and the reciprocating screw (16) extends through the heat exchange groove (10) to the outside. A piston (17) is provided inside the guide tube A (18), and the piston (17) is connected to the ball nut pair of the reciprocating screw (16).
6. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 1, characterized in that: One end of the guide tube A (18) is connected to a connecting tube A (19), the other end of the connecting tube A (19) is connected to a storage tank (20), the outer side of the storage tank (20) is connected to a connecting tube B (21), and an air pressure valve is provided at the connection between the storage tank (20) and the connecting tube B (21).
7. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 1, characterized in that: The other end of the connecting tube B (21) is connected to the guide tube B (22), and one end of the push rod (23) located inside the guide tube B (22) is fixedly connected to a spring (24), and the other end of the spring (24) is connected to the inner wall of the guide tube B (22).
8. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 1, characterized in that: The outer side of the guide tube B (22) is connected to a branch tube (25), and the branch tube (25) is located on the side of the guide tube B (22) close to the output end. The other end of the branch tube (25) is connected to the inside of the delivery tube (9).
9. The heat dissipation structure of a permanent magnet synchronous motor suitable for high-speed operation environment according to claim 4, characterized in that: One side of the heat exchange tank (10) is connected to a connecting pipe C (27), the other end of the connecting pipe C (27) is connected to the water storage tank (3), and one side of the connecting pipe C (27) is connected to a pump (26).