Heat dissipation and cooling mechanism of wind turbine generator

Abstract

The invention provides a heat dissipation and cooling mechanism of a wind turbine generator. Relates to the technical field of wind turbine generators, in particular to a heat dissipation and cooling mechanism of a wind turbine generator, which comprises a wind turbine generator body fixedly mounted at the top of a bottom plate, a cabin cover is arranged at the top of the bottom plate, the wind turbine generator body is positioned in the cabin cover, a protective cover is fixedly mounted at the top of the cabin cover, and a double-shaft motor is fixedly mounted in the protective cover. The two output shafts of the double-shaft motor are fixedly provided with transverse rods correspondingly, the two transverse rods are rotationally connected with the protective cover, the two transverse rods are fixedly sleeved with first belt wheels correspondingly, the outer walls of the two sides of the cabin cover are provided with heat dissipation openings correspondingly, and dustproof nets are fixedly installed in the two heat dissipation openings correspondingly. The heat dissipation and cooling mechanism of the wind turbine generator set has the advantages of being convenient to use and preventing external dust from entering the cabin and adhering to the wind turbine generator set.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine generator sets, and in particular to a heat dissipation and cooling mechanism of a wind turbine generator set. Background Art

[0002] Wind power generation refers to the conversion of wind kinetic energy into electrical energy. Wind energy is a clean, pollution-free, renewable energy source. The use of wind power generation is very environmentally friendly and has huge wind energy reserves, so it is increasingly valued by countries around the world. Wind power generation devices are called wind turbines. Wind turbines can be roughly divided into wind rotors (including tail rudders), generators, towers, nacelles and other structural parts. The nacelle structure is an inner cabin space, in which the generator and other equipment of the unit are installed. Usually in summer, high temperatures will cause the temperature in the cabin to rise. Therefore, in order to reduce the impact of high temperatures on the equipment in the cabin, people generally need to dissipate heat and cool the cabin through heat dissipation and cooling mechanisms.

[0003] However, existing heat dissipation and cooling mechanisms directly discharge the hot air in the cabin through the heat dissipation ports through the heat dissipation fan blades, thereby completing the heat dissipation of the wind turbine. However, external dust will also enter the cabin through the heat dissipation ports and adhere to the wind turbine, affecting the service life of the wind turbine.

[0004] Therefore, it is necessary to provide a heat dissipation and cooling mechanism for a wind turbine to solve the above technical problems.

[0005] Practical Invention Content

[0006] The technical problem solved by the invention is to provide a heat dissipation and cooling mechanism which is easy to use and can prevent external dust from entering the cabin and adhering to the wind turbine set.

[0007] In order to solve the above technical problems, the heat dissipation and cooling mechanism of a wind turbine set provided by the present invention comprises: a wind turbine set body fixedly mounted on the top of a base plate, a nacelle cover is arranged on the top of the base plate, and the wind turbine set body is located in the nacelle cover, a protective cover is fixedly mounted on the top of the nacelle cover, a dual-axis motor is fixedly mounted in the protective cover, cross bars are fixedly mounted on two output shafts of the dual-axis motor, and the two cross bars are rotatably connected to the protective cover, first pulleys are fixedly sleeved on the two cross bars, heat dissipation ports are respectively opened on the outer walls of both sides of the nacelle cover, dustproof nets are fixedly mounted in the two heat dissipation ports, U-shaped plates are fixedly mounted on the inner walls of both sides of the nacelle cover, rotating rods are rotatably mounted on the two U-shaped plates, second pulleys are fixedly sleeved on the ends of the two rotating rods close to each other, synchronous belts are respectively sleeved on the two first pulleys and the second pulleys, and heat dissipation exhaust fan blades are fixedly sleeved on the two rotating rods.

[0008] Preferably, vertical plates are respectively provided on both sides of the nacelle cover, two fixing rods are respectively slidably installed on the two vertical plates, and the four fixing rods are respectively slidably connected to the two vertical plates, rotating tubes are respectively rotatably installed on the two vertical plates, two card slots are respectively provided on the inner walls of the two rotating tubes, mounting tubes are respectively provided in the two rotating tubes, and cleaning brushes are respectively fixedly installed on the ends of the two mounting tubes close to each other, rectangular limiting grooves are respectively provided at the ends of the two rotating rods away from each other, and fixed strong magnet plates are respectively fixedly installed in the two rectangular limiting grooves, strong rectangular magnet strips are respectively fixedly installed on the outer wall of the side where the two cleaning brushes are close to each other, and one side of the two strong rectangular magnet strips extends into the two rectangular limiting grooves respectively, compression springs are respectively provided in the two mounting tubes, and adjusting plates are respectively fixedly installed on both ends of the two compression springs, card plates are respectively fixedly installed on the outer walls of the side where the four adjusting plates are away from each other, and one side of the four card plates extends into the corresponding card slots respectively, and the four card plates are respectively slidably connected to the corresponding mounting tubes.

[0009] Preferably, two guide rods are fixedly installed in the two installation tubes respectively, and the four guide rods are slidably connected to the corresponding adjustment plates respectively.

[0010] Preferably, force springs are movably sleeved on the four fixing rods, and one ends of the four force springs are fixedly connected to the corresponding vertical plates, and the other ends of the four force springs are fixedly connected to the cabin cover.

[0011] Preferably, the compression spring and the force-bearing spring are both tin-plated springs.

[0012] Preferably, a circular baffle is fixedly mounted on one end of the four fixing rods away from the nacelle cover.

[0013] Preferably, fixing plates are fixedly installed on both side inner walls of the cabin cover, extrusion springs are fixedly installed on both side outer walls of the two fixing plates, and push plates are fixedly installed on one end of the four extrusion springs, and the four push plates are respectively in contact with the corresponding synchronous belts.

[0014] Preferably, the push plate is made of polytetrafluoroethylene.

[0015] Preferably, rotation grooves are respectively opened on the inner walls on both sides of the protective cover, the two ends of the two cross bars respectively extend into the two rotation grooves and are respectively fixedly sleeved with bearings, and the outer rings of the two bearings are respectively fixedly connected to the inner walls of the two rotation grooves.

[0016] Compared with the related art, the heat dissipation and cooling mechanism of the wind turbine provided by the present invention has the following beneficial effects:

[0017] The present invention provides a heat dissipation and temperature reduction mechanism for a wind turbine generator set, which pushes two push plates through an extrusion spring to keep the tension of a synchronous belt in a moderate state at all times, thereby reducing the wear of the synchronous belt, and preventing external dust from entering the cabin cover through a dustproof net, adhering to the wind turbine body and affecting the service life of the wind turbine body, and preventing external dust from entering the cabin cover through a dustproof net, adhering to the wind turbine body and affecting the service life of the wind turbine body, and driving the heat dissipation exhaust fan blades to rotate through the rotation of a dual-axis motor to exhaust hot air in the cabin cover to the external environment, thereby completing the heat dissipation and temperature reduction operation of the wind turbine body, and at the same time also driving the cleaning brush to rotate to clean the dust adhered to the dustproof net, thereby preventing the dust from blocking the mesh holes of the dustproof net and affecting the heat dissipation effect of the device, and The dust will be blown away from the dust screen by the strong wind force generated by the heat dissipation fan blades, thereby cleaning the dust screen more thoroughly. When the dust on the dust screen is cleaned, the movable vertical plate moves outward. At this moment, the magnet adsorption force of the fixed strong magnet plate on the strong rectangular magnet strip is remotely smaller than the spring compression force of the force spring. Therefore, the force spring will push the vertical plate to move and contact with the limiting circular plate and stably maintain the current position. When the rotating rod continues to rotate, the cleaning brush will no longer rotate to clean the dust screen, thereby reducing the wear of the cleaning brush and the dust screen and prolonging its service life. By moving the two adjustment plates closer to each other, the two card plates are driven to move out of the card slot, and then the cleaning brush is moved to the right to drive the mounting tube to move out of the rotating tube, and then the cleaning brush is removed from the device for replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the main structure of the heat dissipation and cooling mechanism of the wind turbine set provided by the present invention;

[0019] Figure 2 for Figure 1 An enlarged schematic diagram of section A is shown;

[0020] Figure 3 for Figure 2 An enlarged schematic diagram of portion B is shown;

[0021] Figure 4 for Figure 3 An enlarged schematic diagram of section C is shown;

[0022] Figure 5 for Figure 1 An enlarged schematic diagram of section D is shown;

[0023] Figure 6 for Figure 1 The assembly diagram of the fixed plate, compression spring and push plate shown;

[0024] Figure 7 This is a schematic diagram of the main structure of the heat dissipation and cooling mechanism of the wind turbine set provided by the present invention.

[0025] Numbers in the figure: 1. Base plate; 2. Wind turbine body; 3. Nacelle cover; 4. Protective cover; 5. Dual-axis motor; 6. Cross bar; 7. First pulley; 8. Synchronous belt; 10. U-shaped plate; 11. Dust net; 12. Rotating rod; 13. Second pulley; 14. Cooling ventilator blades; 15. Fixed rod; 16. Vertical plate; 17. Force spring; 18. Cleaning brush; 19. Mounting tube; 20. Rectangular limit groove; 21. Strong rectangular magnet strip; 22. Fixed strong magnet plate; 23. Rotating tube; 24. Card slot; 25. Card plate; 26. Compression spring; 27. Adjustment plate; 28. Guide rod; 29. ​​Fixed plate; 30. Extrusion spring; 31. Push plate. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0027] Please refer to Figure 1-Figure 7In the present invention, the heat dissipation and cooling mechanism of the wind turbine generator set includes a wind turbine generator set body 2 fixedly mounted on the top of the base plate 1, a cabin cover 3 is arranged on the top of the base plate 1, and the wind turbine generator set body 2 is located in the cabin cover 3, a protective cover 4 is fixedly mounted on the top of the cabin cover 3, a dual-axis motor 5 is fixedly mounted in the protective cover 4, cross bars 6 are respectively fixedly mounted on the two output shafts of the dual-axis motor 5, and the two cross bars 6 are rotatably connected with the protective cover 4, and first pulleys 7 are respectively fixedly sleeved on the two cross bars 6. In order to rotatably mount the cross bars 6 in the protective cover 4, rotation grooves are respectively opened on the inner walls on both sides of the protective cover 4, the two ends of the two cross bars 6 extend into the two rotation grooves respectively and are respectively fixedly sleeved with bearings, and the outer rings of the two bearings are respectively fixedly connected with the inner walls of the two rotation grooves, and the bearings make the rotation of the cross bars 6 in the protective cover 4 more stable, and heat dissipation ports are respectively opened on the outer walls on both sides of the cabin cover 3, and the two heat dissipation ports are respectively opened on the outer walls on both sides of the cabin cover 3. Dust-proof nets 11 are fixedly installed in the openings, and the dust-proof nets 11 prevent external dust from entering the nacelle cover 3 and adhering to the wind turbine body 2, thereby affecting the service life of the wind turbine body 2. U-shaped plates 10 are fixedly installed on the inner walls of both sides of the nacelle cover 3, and rotating rods 12 are rotatably installed on the two U-shaped plates 10. The ends of the two rotating rods 12 close to each other are fixedly sleeved with second pulleys 13, and the two first pulleys 7 and the second pulleys 13 are respectively sleeved with synchronous belts 8. The two rotating rods 12 are respectively fixedly sleeved with heat dissipation fan blades 14, and the rotation of the dual-axis motor 5 drives the cross bar 6 and the first pulley 7 to rotate, and the second pulley 13 and the rotating rod 12 are driven to rotate by the synchronous belt 8. The rotation of the rotating rod 12 drives the heat dissipation fan blades 14 to rotate, and the hot air in the nacelle cover 3 is discharged to the external environment, thereby completing the heat dissipation and cooling operation of the wind turbine body 2.

[0028] In order to clean the dustproof net 11 and prevent dust and other impurities from blocking the mesh holes of the dustproof net 11 and affecting the heat dissipation efficiency of the wind turbine body 2, vertical plates 16 are respectively arranged on both sides of the nacelle cover 3, two fixing rods 15 are respectively slidably installed on the two vertical plates 16, and the four fixing rods 15 are respectively slidably connected to the two vertical plates 16, and rotating tubes 23 are respectively rotatably installed on the two vertical plates 16, and two card grooves 24 are respectively provided on the inner walls of the two rotating tubes 23, and mounting tubes 19 are respectively provided in the two rotating tubes 23, and cleaning brushes 18 are respectively fixedly installed on the ends of the two mounting tubes 19 close to each other, and rectangular limiting grooves 20 are respectively provided at the ends of the two rotating rods 12 away from each other, and fixed strong magnet plates 22 are respectively fixedly installed in the two rectangular limiting grooves 20, and strong rectangular magnet strips 21 are respectively fixedly installed on the outer walls of the two cleaning brushes 18 close to each other, and the attraction of the strong rectangular magnet strips 21 by the fixed strong magnet plates 22 is used to clean the dustproof net 11. The cleaning brush 18 is always in close contact with the dustproof net 11, so that the dustproof net 11 can be cleaned, and one side of the two strong rectangular magnet strips 21 extends into the two rectangular limiting grooves 20 respectively. At the same time, since the strong rectangular magnet strip 21 and the rectangular limiting groove 20 are both rectangular, when the rotating rod 12 rotates, the strong rectangular magnet strip 21 can be driven to rotate, and finally the cleaning brush 18 can be driven to rotate. Compression springs 26 are respectively arranged in the two mounting tubes 19, and adjustment plates 27 are respectively fixedly installed at both ends of the two compression springs 26. Through the compression springs 26, one side of the card plate 25 is always located in the card groove 24 without being affected by other external forces, and then the mounting tube 19 and the cleaning brush 18 are installed on the device. Card plates 25 are respectively fixedly installed on the outer walls of the sides of the four adjustment plates 27 away from each other, and one side of the four card plates 25 extends into the corresponding card groove 24 respectively, and the four card plates 25 are respectively slidably connected with the corresponding mounting tubes 19.

[0029] In order to guide the adjustment plate 27 and thus ensure that the clamping plate 25 always stably moves into the clamping slot 24 , two guide rods 28 are fixedly installed in the two mounting tubes 19 , respectively, and the four guide rods 28 are slidably connected to the corresponding adjustment plates 27 .

[0030] In order to allow the cleaning brush 18 to be stably maintained at a position away from the dustproof net 11 when people do not need to clean the dustproof net 11, thereby reducing the wear of the cleaning brush 18 and the dustproof net 11 and increasing their service life, force springs 17 are movably sleeved on the four fixed rods 15. In order to extend the service life of the compression springs 26 and the force springs 17, the compression springs 26 and the force springs 17 are tin-plated springs, and one end of the four force springs 17 are respectively fixedly connected to the corresponding vertical plates 16, and the other ends of the four force springs 17 are fixedly connected to the cabin cover 3.

[0031] In order to limit the cleaning brush 18 so that the cleaning brush 18 can always be stably maintained at the current stable position under the thrust of the force spring 17 , a circular baffle is fixedly installed at one end of the four fixing rods 15 away from the nacelle cover 3 .

[0032] In order to always keep the tension of the synchronous belt 8 at a moderate state and thereby reduce the wear of the synchronous belt 8, fixing plates 29 are fixedly installed on the inner walls on both sides of the engine cover 3, and extrusion springs 30 are fixedly installed on the outer walls on both sides of the two fixing plates 29, and one end of the four extrusion springs 30 is fixedly installed with a push plate 31. In order to reduce the friction between the push plate 31 and the synchronous belt 8, thereby reducing the wear of the synchronous belt 8 and increasing the service life of the synchronous belt 8, the push plate 31 is made of polytetrafluoroethylene, and the four push plates 31 are respectively in contact with the corresponding synchronous belts 8.

[0033] The working principle of the heat dissipation and cooling mechanism of the wind turbine provided by the present invention is as follows; in the initial state, the force spring 17, the compression spring 26 and the extrusion spring 30 are all in a compressed state, and the strong rectangular magnet strip 21 is adsorbed by the fixed strong magnet plate 22 but does not contact the fixed strong magnet plate 22. At this moment, the magnet adsorption force of the fixed strong magnet plate 22 on the strong rectangular magnet strip 21 is greater than the spring compression force of the force spring 17, so that the bristles on the cleaning brush 18 are tightly contacted with the dustproof net 11, and the extrusion spring 30 pushes the two push plates 31 to always push the same synchronous belt 8 tightly, so that the tension of the synchronous belt 8 is always maintained in a moderate state, thereby reducing the wear of the synchronous belt 8, and preventing external dust from entering the cabin cover 3 through the dustproof net 11, adhering to the wind turbine body 2, and affecting the service life of the wind turbine body 2.

[0034] When the temperature of the wind turbine body 2 is too high, the dual-axis motor 5 is started to rotate to drive the cross bar 6 and the first pulley 7 to rotate, and the second pulley 13 and the rotating rod 12 are driven to rotate through the synchronous belt 8. The rotation of the rotating rod 12 drives the heat dissipation fan blades 14 to rotate, and the hot air in the cabin cover 3 is discharged to the external environment, thereby completing the heat dissipation and cooling operation of the wind turbine body 2. At the same time, the rotation of the rotating rod 12 drives the strong rectangular magnet bar 21 to rotate, and the rotation of the strong rectangular magnet bar 21 drives the cleaning brush 18 to rotate to clean the dust adhered to the dustproof net 11, so as to prevent the dust from blocking the mesh holes of the dustproof net 11 and affecting the heat dissipation effect of the device. The cleaned dust will be blown away from the dustproof net 11 by the strong wind force generated by the heat dissipation fan blades 14, so as to clean the dustproof net 11 more cleanly. When the dust on the dustproof net 11 is cleaned, the vertical plate 1 is moved. 6 moves outward to drive the strong rectangular magnet strip 21 to move out of the rectangular limiting groove 20 and away from the fixed strong magnet plate 22. At this moment, the magnet adsorption force of the fixed strong magnet plate 22 on the strong rectangular magnet strip 21 is remotely smaller than the spring compression force of the force spring 17. Therefore, the force spring 17 will push the vertical plate 16 to move and contact with the limiting circular plate and stably maintain the current position. When the rotating rod 12 continues to rotate, the cleaning brush 18 will no longer rotate to clean the dustproof net 11, thereby reducing the wear of the cleaning brush 18 and the dustproof net 11 and improving the service life. When the cleaning brush 18 needs to be replaced, the two adjustment plates 27 are moved closer to each other to drive the two card plates 25 to move out of the card slot 24, and then the cleaning brush 18 is moved to the right to drive the mounting tube 19 to move out of the rotating tube 23, and then the cleaning brush 18 is removed from the device for replacement.

[0035] Compared with the related art, the heat dissipation and cooling mechanism of the wind turbine provided by the present invention has the following beneficial effects:

[0036] The present invention provides a heat dissipation and cooling mechanism for a wind turbine generator set. The two pushing plates 31 are pushed by an extrusion spring 30 so that the tension of the synchronous belt 8 is always maintained in a moderate state, thereby reducing the wear of the synchronous belt 8. The dust-proof net 11 is used to prevent external dust from entering the cabin cover 3 and adhering to the wind turbine body 2, thereby affecting the service life of the wind turbine body 2. The dust-proof net 11 is used to prevent external dust from entering the cabin cover 3 and adhering to the wind turbine body 2, thereby affecting the service life of the wind turbine body 2. The heat dissipation exhaust fan blades 14 are driven to rotate by the rotation of the dual-axis motor 5 to exhaust the hot air in the cabin cover 3 to the external environment, thereby completing the heat dissipation and cooling operation of the wind turbine body 2. At the same time, the cleaning brush 18 is also driven to rotate to clean the dust adhered to the dust-proof net 11, thereby preventing the dust from blocking the mesh holes on the dust-proof net 11 and affecting the heat dissipation effect of the device. The cleaned dust will be blown by the heat dissipation exhaust fan The strong wind force generated by the blades 14 blows away the dust net 11, thereby cleaning the dust net 11 more thoroughly. When the dust on the dust net 11 is cleaned, the movable vertical plate 16 moves outward. At this moment, the magnetic adsorption force of the fixed strong magnet plate 22 on the strong rectangular magnet strip 21 is remotely less than the spring compression force of the force spring 17. Therefore, the force spring 17 will push the vertical plate 16 to move and contact with the limiting circular plate and stably maintain the current position. When the rotating rod 12 continues to rotate, the cleaning brush 18 will no longer rotate to clean the dust net 11, thereby reducing the wear of the cleaning brush 18 and the dust net 11 and improving the service life. By moving the two adjustment plates 27 closer to each other, the two card plates 25 are driven to move out of the card slot 24, and then the cleaning brush 18 is moved to the right to drive the mounting tube 19 to move out of the rotating tube 23, and then the cleaning brush 18 is removed from the device for replacement.

[0037] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A heat dissipation and cooling mechanism for a wind turbine generator set, comprising a wind turbine generator set body fixedly mounted on the top of a base plate, characterized in that: A nacelle cover is provided on the top of the base plate, and the wind turbine body is located in the nacelle cover, a protective cover is fixedly installed on the top of the nacelle cover, a dual-axis motor is fixedly installed in the protective cover, cross bars are respectively fixedly installed on the two output shafts of the dual-axis motor, and the two cross bars are rotatably connected to the protective cover, and a first pulley is fixedly sleeved on the two cross bars, and heat dissipation ports are respectively opened on the outer walls of the nacelle cover, and dustproof nets are respectively fixedly installed in the two heat dissipation ports, and U-shaped plates are respectively fixedly installed on the inner walls of the nacelle cover, and rotating rods are respectively rotatably installed on the two U-shaped plates, and second pulleys are respectively fixedly sleeved on the ends of the two rotating rods close to each other, synchronous belts are respectively sleeved on the two first pulleys and the second pulleys, and heat dissipation exhaust fan blades are respectively fixedly sleeved on the two rotating rods.

2. The heat dissipation and cooling mechanism of a wind turbine according to claim 1, characterized in that: A vertical plate is provided on both sides of the nacelle cover, two fixing rods are slidably installed on the two vertical plates, and the four fixing rods are slidably connected to the two vertical plates, and a rotating tube is rotatably installed on the two vertical plates, and two card slots are respectively provided on the inner walls of the two rotating tubes, and a mounting tube is provided in the two rotating tubes, and a cleaning brush is fixedly installed on the ends of the two mounting tubes close to each other, and a rectangular limiting groove is provided at the ends of the two rotating rods away from each other, and a fixed strong magnet plate is fixedly installed in the two rectangular limiting grooves, and a strong rectangular magnet strip is fixedly installed on the outer wall of the side where the two cleaning brushes are close to each other, and one side of the two strong rectangular magnet strips extends into the two rectangular limiting grooves, respectively, a compression spring is provided in the two mounting tubes, and an adjusting plate is fixedly installed on both ends of the two compression springs, and a card plate is fixedly installed on the outer wall of the side where the four adjusting plates are away from each other, and one side of the four card plates extends into the corresponding card slots, and the four card plates are slidably connected to the corresponding mounting tubes.

3. The heat dissipation and cooling mechanism of a wind turbine according to claim 2, characterized in that: Two guide rods are fixedly installed in the two installation tubes respectively, and the four guide rods are slidably connected to the corresponding adjustment plates respectively.

4. The heat dissipation and cooling mechanism of a wind turbine according to claim 3, characterized in that: Forced springs are movably sleeved on the four fixing rods, and one end of the four forced springs is fixedly connected to the corresponding vertical plates, and the other ends of the four forced springs are fixedly connected to the nacelle cover.

5. The heat dissipation and cooling mechanism of a wind turbine according to claim 4, characterized in that: The compression spring and the force spring are both tin-plated springs.

6. The heat dissipation and cooling mechanism of a wind turbine according to claim 5, characterized in that: A circular baffle is fixedly mounted on one end of the four fixing rods away from the nacelle cover.

7. The heat dissipation and cooling mechanism of a wind turbine according to claim 6, characterized in that: Fixed plates are fixedly installed on the inner walls on both sides of the nacelle cover, extrusion springs are fixedly installed on the outer walls on both sides of the two fixed plates, and push plates are fixedly installed on one end of the four extrusion springs, and the four push plates are respectively in contact with the corresponding synchronous belts.

8. The heat dissipation and cooling mechanism of a wind turbine according to claim 7, characterized in that: The push plate is made of polytetrafluoroethylene.

9. The heat dissipation and cooling mechanism of a wind turbine according to claim 8, characterized in that: Rotation grooves are respectively opened on the inner walls of both sides of the protective cover, and the two ends of the two cross bars extend into the two rotation grooves and are respectively fixedly sleeved with bearings, and the outer rings of the two bearings are respectively fixedly connected to the inner walls of the two rotation grooves.

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