A solar photovoltaic power generation device with self-cleaning function

Abstract

The present invention belongs to the technical field of solar photovoltaic power generation devices, and specifically relates to a solar photovoltaic power generation device with a self-cleaning function, including a photovoltaic panel and a cleaning mechanism. The cleaning mechanism includes a displacement frame, a control valve, a water spray pipe, a cleaning roller, a first drive mechanism and a second drive mechanism. The control valve includes a cylinder shell, a piston, an elastic member and a ball. The present invention discloses a solar photovoltaic power generation device with a self-cleaning function. The device has a cleaning mechanism, which can flush and scrub the photovoltaic panel. There is no need for staff to climb to a high place for manual cleaning, which has high safety and can automatically change the cleaning position. Compared with manual cleaning, it can greatly improve cleaning efficiency, save labor costs, and is conducive to the promotion and use of photovoltaic energy. In addition, the cleaning mechanism can avoid dry wiping of the photovoltaic panel and can protect the photovoltaic panel.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar photovoltaic power generation devices, and in particular relates to a solar photovoltaic power generation device with a self-cleaning function. Background Art

[0002] Solar photovoltaic power generation devices need to be installed in outdoor areas with sufficient sunlight, and are usually at a certain height from the ground to achieve the purpose of effectively utilizing light energy and space. Because solar photovoltaic power generation devices are generally installed outdoors in the open air, outdoor dust and dirt will inevitably cover the surface of the solar panels. Therefore, during use, some dust or other dirt will be deposited on the surface of the solar panels, which greatly reduces the transmittance of the solar panels and reduces the effective area that can receive sunlight. Therefore, during the use of solar panels, the solar panels need to be cleaned regularly to keep them in the best working condition during use. Existing cleaning methods usually require personnel to climb to a high place for manual cleaning, or use long-handled cleaning tools for cleaning. This method not only has safety hazards but also has low cleaning efficiency. Therefore, in response to the above problems, we have proposed a solar photovoltaic power generation device with a self-cleaning function. Summary of the Invention

[0003] In order to overcome the problems existing in the related art, the present invention discloses a solar photovoltaic power generation device with a self-cleaning function.

[0004] To achieve the above object, a technical solution adopted by the present invention is:

[0005] A solar photovoltaic power generation device with a self-cleaning function includes a photovoltaic panel and a cleaning mechanism, the cleaning mechanism includes a displacement frame, a control valve, a water spray pipe, a cleaning roller, a first drive mechanism and a second drive mechanism, the displacement frame has two, the two displacement frames are symmetrically slidably assembled on the left and right sides of the photovoltaic panel, the displacement frames have semicircular cleaning roller support seats on opposite sides, the cleaning roller will be coaxial with the cleaning roller support seats when placed between the two cleaning roller support seats, the water spray pipe is fixed between the two displacement frames, at least one of the two displacement frames is provided with a first drive mechanism, the first drive mechanism is used to drive the displacement frame to move along the photovoltaic panel, the control valve and the second drive mechanism are respectively provided on the left and right displacement frames;

[0006] The control valve includes a cylinder shell, a piston, an elastic member and a ball, the cylinder shell passes through the displacement frame and is coaxially arranged on the cleaning roller support seat, a branch pipe connected to the water spray pipe is provided on the side of the cylinder shell, an end of the cylinder shell away from the cleaning roller is connected to an external water source, the piston is sealingly and slidably connected to the cylinder shell, an end of the piston close to the external water source is provided with a water guide groove passing through the side of the piston, the water guide groove can slide axially with the piston to be aligned with the branch pipe, the elastic member is provided in the cylinder shell for pushing the piston toward the side of the external water source, so that the side end of the water guide groove can be completely staggered with the branch pipe when the piston is not pushed by water pressure, and the ball is rotatably connected to the right end of the piston and is concentric with the cleaning roller support seat;

[0007] The second driving mechanism includes a driving motor and a friction plate, wherein the driving motor is provided on the displacement frame, the friction plate is fixedly connected to the output end of the driving motor, and the rotation axis of the friction plate is coaxial with the cleaning roller support seat;

[0008] When water from an external water source is pumped into the cylinder shell, it will push the piston to overcome the elastic force of the elastic part and move to the right. When the piston moves until the ball contacts the cleaning roller, it will push the cleaning roller to the right until it contacts the friction plate tightly. In this state, the side end of the water guide groove will be aligned with the branch pipe. In this state, when the drive motor drives the friction plate to rotate, the friction plate will drive the cleaning roller to rotate through friction force.

[0009] Furthermore, both ends of the cleaning roller are provided with insertion holes for inserting the piston.

[0010] Furthermore, the right side of the piston is truncated cone-shaped.

[0011] Furthermore, the ball is rotatably connected to a ball seat, and the ball seat is fixed to the right end of the piston.

[0012] Furthermore, there are two water spray pipes, which are respectively located on the front and rear sides of the cleaning roller. Two branch pipes are provided on the side of the cylinder shell, which are respectively connected to the two water spray pipes. The water guide groove has two side ends, and the two side ends of the water guide groove respectively match the positions of the two branch pipes.

[0013] Furthermore, the branch pipe is connected to the water spray pipe via a bend joint.

[0014] Furthermore, the piston side has an axially extending convex strip, the inner side of the cylinder shell is provided with a convex strip groove matching the convex strip, and the convex strip is slidably assembled in the convex strip groove.

[0015] Furthermore, a first abutting ring is provided at the right end of the cylinder shell, a step surface is provided at the middle portion of the piston, and the left and right ends of the elastic member abut against the step surface of the piston and the first abutting ring respectively.

[0016] Furthermore, a second abutting ring located on the left side of the piston is fixedly connected to the inner side of the cylinder shell. When the left end of the piston abuts against the cylinder shell, the side end of the water guide groove is completely staggered with the branch pipe.

[0017] Furthermore, the displacement frame has two groups of rollers distributed upper and lower on the side facing the photovoltaic panel, and the upper and lower groups of rollers are respectively abutted against the upper and lower ends of the photovoltaic panel. Among the upper and lower groups of rollers, at least one group has a number of rollers greater than 1, and the first driving mechanism is used to drive at least one of the rollers to rotate.

[0018] The present invention discloses a solar photovoltaic power generation device with a self-cleaning function. The device has a cleaning mechanism, which can flush and scrub the photovoltaic panels. There is no need for workers to climb to a high place for manual cleaning. The cleaning position is relatively safe and can automatically change. Compared with manual cleaning, the cleaning efficiency can be greatly improved. At the same time, it can also save labor costs and is conducive to the promotion and use of photovoltaic energy. In addition, the cleaning mechanism can also avoid dry wiping of the photovoltaic panels and can protect the photovoltaic panels. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0020] Figure 1 A schematic structural diagram of an embodiment of the present invention;

[0021] Figure 2 for Figure 1 A schematic diagram of the structure at center A;

[0022] Figure 3 for Figure 1 A magnified schematic diagram of the structure at B in the middle;

[0023] Figure 4 Schematic diagram of the cross-sectional structure of a cleaning mechanism in one embodiment of the present invention;

[0024] Figure 5 for Figure 4 A magnified schematic diagram of the structure at C in the middle;

[0025] Figure 6 for Figure 4 A schematic diagram of the structure at D in the middle;

[0026] Figure 7 This is a schematic structural diagram of a piston in one embodiment of the present invention;

[0027] Figure 8This is a schematic structural diagram of a displacement frame in one embodiment of the present invention;

[0028] Figure 9 Schematic diagram of the structure of a cleaning roller in one embodiment of the present invention.

[0029] The meanings of the reference numerals in the accompanying drawings are:

[0030] Photovoltaic panel 1, cleaning mechanism 2, displacement frame 21, cleaning roller support seat 211, roller 212, control valve 22, cylinder shell 221, convex groove 2211, first abutting ring 2212, second abutting ring 2213, piston 222, water guide groove 2221, convex strip 2222, elastic member 223, ball bearing 224, branch pipe 225, turning joint 226, water spray pipe 23, cleaning roller 24, insertion hole 241, first drive mechanism 25, second drive mechanism 26, drive motor 261, friction plate 262. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] Reference Figures 1-9 As shown, the solar photovoltaic power generation device of this embodiment includes a photovoltaic panel 1 and a cleaning mechanism 2. The photovoltaic panel 1 is supported on the ground by a support rod. When the photovoltaic panel 1 is installed, it should be installed facing the sun.

[0033] The cleaning mechanism 2 specifically includes a displacement frame 21, a control valve 22, a water spray pipe 23, a cleaning roller 24, a first drive mechanism 25, and a second drive mechanism 26. There are two displacement frames 21, which are symmetrically slidably assembled on the left and right sides of the photovoltaic panel 1. Specifically, the displacement frame 21 has two sets of rollers 212 distributed vertically on the side facing the photovoltaic panel 1. The upper and lower sets of rollers 212 are respectively in contact with the upper and lower ends of the photovoltaic panel 1. In the upper and lower sets of rollers 212, there are two rollers 212 in each set. In this embodiment, the right displacement frame 21 is provided with a first drive mechanism 25. The first drive mechanism 25 is used to drive the displacement frame 21 to move along the photovoltaic panel 1. Specifically, the first drive mechanism 25 is used to drive one of the rollers 212 to rotate. There should be a certain pressure and friction between the upper and lower sets of rollers 212 and the photovoltaic panel 1. The rollers 212 can be made of rubber material. In this way, the actively rotating rollers 212 can drive the right displacement frame 21 to move on the photovoltaic panel 1. In this embodiment, the water spray pipe 23 is fixed between the two displacement frames 21. In addition to being used to spray water on the photovoltaic panel 1, the water spray pipe 23 is also used to connect the two displacement frames 21 so that the three form a whole. In this way, when the right displacement frame 21 moves, the water spray pipe 23 will drive the left displacement frame 21 to move together.

[0034] In this embodiment, the displacement frame 21 has semicircular cleaning roller support seats 211 on opposite sides. The two cleaning roller support seats 211 are used to accommodate the cleaning roller 24. When the cleaning roller 24 is placed between the two cleaning roller support seats 211, it will be coaxial with the cleaning roller support seats 211. In this embodiment, both ends of the cleaning roller support seats 211 extend upward to form side edges that are fixed to the displacement frame 21. This arrangement can enhance the connection strength between the cleaning roller support seats 211 and the displacement frame 21, and also provide a guide for the user to remove and place the cleaning roller 24.

[0035] In this embodiment, the cleaning roller 24 includes a roller shaft and a cleaning cotton tube. The roller shaft is used to connect to the cleaning roller support seat 211. The cleaning cotton tube is fixed to the outside of the roller shaft. The cleaning cotton tube is used to contact the photovoltaic panel 1. When the roller shaft rotates, the photovoltaic panel 1 can be brushed.

[0036] The control valve 22 and the second driving mechanism 26 are respectively disposed on the left and right displacement frames 21 .

[0037] The control valve 22 specifically includes a cylinder shell 221, a piston 222, an elastic member 223, and a ball 224. The cylinder shell 221 passes through the displacement frame 21 and is coaxially arranged with the cleaning roller support seat 211. It is preferred that the right end of the cylinder shell 221 does not extend into the cleaning roller support seat 211 so that the cleaning roller 24 can be smoothly placed in the cleaning roller support seat 211 on this side. A branch pipe 225 connected to the water spray pipe 23 is provided on the side of the cylinder shell 221. The branch pipe 225 and the water spray pipe 23 are specifically connected by a bend joint 226. The end of the cylinder shell 221 away from the cleaning roller 24 is connected to an external water source through a pipe that is sealed and rotatably connected to the cylinder shell 221. The piston 222 is sealed and slidably connected to the cylinder shell 221. The end of the piston 222 close to the external water source is provided with a water guide groove 2222 that runs through the side of the piston 222. The water guide groove 2222 can be adjusted as needed. The piston 222 slides axially until it is aligned with the branch pipe 225. A first abutting ring 2212 is provided at the right end of the cylindrical shell 221. The piston 222 has a stepped surface in the middle. The left and right ends of the elastic member 223 respectively abut the stepped surface of the piston 222 and the first abutting ring 2212. Under the action of its own elastic force, the elastic member 223 pushes the piston 222 toward the external water source, so that when the piston 222 is not pushed by water pressure, the side end of the water channel 2222 can be completely offset from the branch pipe 225. Furthermore, a second abutting ring 2213 is fixedly attached to the inner side of the cylindrical shell 221, located on the left side of the piston 222. When the piston 222 is not pushed by water pressure, the elastic member 223 can push the cylindrical shell 221 leftward until it abuts the second abutting ring 2213. When abutting, the side end of the water channel 2222 is completely offset from the branch pipe 225. The provision of the second abutting ring 2213 thus limits the leftward movement of the piston 222. The ball 224 is rotatably connected to the right end of the piston 222 and is concentric with the cleaning roller support seat 211 . Specifically, the ball 224 is rotatably connected to the ball seat, and the ball seat is fixed to the right end of the piston 222 .

[0038] The second driving mechanism 26 includes a driving motor 261 and a friction plate 262. The driving motor 261 is arranged on the displacement frame 21. The friction plate 262 is fixedly connected to the output end of the driving motor 261. The rotation axis of the friction plate 262 is coaxial with the cleaning roller support seat 211. It is preferred that the left end of the friction plate 262 does not extend into the cleaning roller support seat 211 so that the cleaning roller 24 can be smoothly placed in the cleaning roller support seat 211 on this side.

[0039] In this state, the cleaning mechanism 2 will not work, the water from the external water source will not be pumped into the cylinder shell 221, and the piston 222 will not be pushed by the water pressure. In this state, the elastic member 223 will push the piston 222 to the left under its own elastic force, so that the side end of the water guide groove 2222 can be completely offset from the branch pipe 225. In this state, the water spray pipe 23 will be in a non-spraying state. In this state, the ball 224 at the right end of the piston 222 will be completely retracted into the cylinder shell 221, that is, it will not abut against the cleaning roller 24. In this way, the cleaning roller 24 will be loose in the cleaning roller support seat 211, and the user can directly and easily take it out in this state. Since the right end of the cleaning roller 24 is not abutted or tightly abutted against the friction plate 262, in this state, when the driving motor 261 drives the friction plate 262 to rotate, the friction plate 262 can be prevented from driving the cleaning roller 24 to rotate, so as to prevent the cleaning roller 24 from dry wiping the photovoltaic panel 1 when the water spray pipe 23 is not spraying water, thereby protecting the photovoltaic panel 1.

[0040] When cleaning the photovoltaic panel 1, the external water source is controlled to pump water into the cylindrical shell 221. The water entering the cylindrical shell 221 will push the piston 222 to overcome the elastic force of the elastic member 223 and move to the right. When the piston 222 moves until the ball 224 abuts against the cleaning roller 24, it will push the cleaning roller 24 to move to the right until it is tightly abutted against the friction plate 262. In this state, the side end of the water guide groove 2222 will be aligned with the branch pipe 225. In this state, the water in the cylindrical shell 221 will enter the water spray pipe 23 through the branch pipe 225, so that the water spray pipe 23 can spray water onto the photovoltaic panel 1 to rinse the photovoltaic panel 1. After the water pipe 23 sprays water, the drive motor 261 is controlled to drive the friction plate 262 to rotate. When the friction plate 262 rotates, the cleaning roller 24 will be driven to rotate by the friction force, and the rotating cleaning roller 24 will scrub the photovoltaic panel 1. At this time, the entire cleaning mechanism 2 can also be driven by the first driving mechanism 25 to move up and down along the photovoltaic panel 1, so that the entire photovoltaic panel 1 can be automatically scrubbed. It can be seen that when this cleaning method is used to clean the photovoltaic panel, there is no need for staff to climb to a high place for manual cleaning, which is safer and can automatically change the cleaning position. Compared with manual cleaning, it can greatly improve the cleaning efficiency, save labor costs, and is conducive to the promotion and use of photovoltaic energy.

[0041] It should be emphasized that since the piston 222 is in contact with the cleaning roller 24 via the ball bearing 224, when the left end of the cleaning roller 24 is tightly contacted, it is equivalent to being rotationally connected to the right end of the piston 222. Correspondingly, the friction plate 262 is made of a material with a high coefficient of friction, such as a structure in which a rubber pad is fixedly attached to the surface of a metal plate. Thus, when the right end of the cleaning roller 24 is tightly contacted, it is equivalent to being fixedly connected to the left end of the friction plate 262. Thus, when the friction plate 262 rotates, it can drive the cleaning roller 24 to rotate. Since the ball bearing 224 is concentric with the cleaning roller support 211 and the rotation axis of the friction plate 262 is coaxial with the cleaning roller support 211, the cleaning roller 24 will be coaxial with the cleaning roller support 211 when placed between the two cleaning roller support 211. Therefore, when the friction plate 262 rotates, it will drive the cleaning roller 24 to rotate coaxially, thereby ensuring the rotational stability of the cleaning roller 24.

[0042] When the cleaning mechanism 2 stops cleaning, no water will be pumped into the shell 221, and the piston 222 will push the piston 222 back into the shell 221 under the elastic force of the elastic member 223, so that the cleaning roller 24 will be released from the abutment, and the cleaning roller 24 will be restored to a state that can be taken out at any time. In this way, when the cleaning roller 24 needs to be replaced, it can be directly removed, and the reinstallation operation can also be directly put in. It can be seen that the replacement operation of the cleaning roller 24 of the cleaning mechanism 2 is very convenient, which is beneficial for the user to maintain the cleaning mechanism 2.

[0043] In this embodiment, both ends of the cleaning roller 24 are provided with insertion holes 241 for the piston 222 to be inserted. When the piston 222 moves to the right, it will be inserted into the insertion hole 241 until the ball 224 abuts against the bottom wall of the insertion hole 241. This can play a radial limiting role on the cleaning roller 24, preventing the cleaning roller 24 from detaching from the cleaning roller support seat 211 when rotating, so as to improve the safety of the cleaning mechanism 2 during operation. When the control valve 22 stops supplying water, the piston 222 will automatically withdraw from the insertion hole 241 under the elastic force of the elastic member 223. The insertion holes 241 are provided at both ends of the cleaning roller 24, so that the installation direction does not need to be distinguished when the cleaning roller 24 is installed, thereby improving the convenience of installation. Furthermore, the right side of the piston 222 is truncated cone-shaped, so that the piston 222 can be smoothly inserted into the insertion hole 241.

[0044] In this embodiment, there are two water spray pipes 23, located on the front and rear sides of the cleaning roller 24. Two branch pipes 225 are provided on the side of the cylindrical shell 221, each connected to the two water spray pipes 23. The water guide groove 2222 has two side ends, and the two side ends of the water guide groove 2222 match the positions of the two branch pipes 225. This arrangement allows water to be sprayed from both the front and rear sides of the cleaning roller 24, so that the cleaning roller 24 is exposed to water regardless of whether it moves forward or backward. In addition, a cleaning process of rinsing first, scrubbing second, and rinsing third can be formed to further improve the cleaning effect.

[0045] The piston 222 has an axially extending ridge 2221 on its side, and the inner side of the cylinder shell 221 has a ridge groove 2211 matching the ridge 2221 . The ridge 2221 is slidably assembled in the ridge groove 2211 , so that the piston 222 is prevented from rotating relative to the cylinder shell 221 .

[0046] In summary, the present invention discloses a solar photovoltaic power generation device with a self-cleaning function. The device has a cleaning mechanism, which can flush and scrub the photovoltaic panels. There is no need for staff to climb to a high place for manual cleaning. The device is safer and can automatically change the cleaning position. Compared with manual cleaning, the cleaning efficiency can be greatly improved. At the same time, it can also save labor costs and is conducive to the promotion and use of photovoltaic energy. In addition, the cleaning mechanism can also avoid dry wiping of the photovoltaic panels and can protect the photovoltaic panels.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A solar photovoltaic power generation device with a self-cleaning function, comprising a photovoltaic panel and a cleaning mechanism, characterized in that: The cleaning mechanism includes a displacement frame, a control valve, a water spray pipe, a cleaning roller, a first driving mechanism and a second driving mechanism, wherein the displacement frame has two, and the two displacement frames are symmetrically slidably assembled on the left and right sides of the photovoltaic panel, and the displacement frame has a semicircular cleaning roller support seat on the opposite side. When the cleaning roller is placed between the two cleaning roller support seats, it will be coaxial with the cleaning roller support seat, and the water spray pipe is fixed between the two displacement frames. At least one of the two displacement frames is provided with a first driving mechanism, and the first driving mechanism is used to drive the displacement frame to move along the photovoltaic panel. The control valve and the second driving mechanism are respectively provided on the left and right displacement frames; The control valve includes a cylinder shell, a piston, an elastic member and a ball, the cylinder shell passes through the displacement frame and is coaxially arranged on the cleaning roller support seat, a branch pipe connected to the water spray pipe is provided on the side of the cylinder shell, an end of the cylinder shell away from the cleaning roller is connected to an external water source, the piston is sealingly and slidably connected to the cylinder shell, an end of the piston close to the external water source is provided with a water guide groove passing through the side of the piston, the water guide groove can slide axially with the piston to be aligned with the branch pipe, the elastic member is provided in the cylinder shell for pushing the piston toward the side of the external water source, so that the side end of the water guide groove can be completely staggered with the branch pipe when the piston is not pushed by water pressure, and the ball is rotatably connected to the right end of the piston and is concentric with the cleaning roller support seat; The second driving mechanism includes a driving motor and a friction plate, wherein the driving motor is provided on the displacement frame, the friction plate is fixedly connected to the output end of the driving motor, and the rotation axis of the friction plate is coaxial with the cleaning roller support seat; When water from an external water source is pumped into the cylinder shell, it will push the piston to overcome the elastic force of the elastic part and move to the right. When the piston moves until the ball contacts the cleaning roller, it will push the cleaning roller to the right until it contacts the friction plate tightly. In this state, the side end of the water guide groove will be aligned with the branch pipe. In this state, when the drive motor drives the friction plate to rotate, the friction plate will drive the cleaning roller to rotate through friction force.

2. A solar photovoltaic power generation device with a self-cleaning function according to claim 1, characterized in that: Both ends of the cleaning roller are provided with insertion holes for inserting the piston.

3. A solar photovoltaic power generation device with a self-cleaning function according to claim 2, characterized in that: The right side of the piston is in the shape of a truncated cone.

4. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: The ball is rotatably connected to a ball seat, and the ball seat is fixed to the right end of the piston.

5. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: There are two water spray pipes, which are respectively located on the front and rear sides of the cleaning roller. Two branch pipes are provided on the side of the cylinder shell, which are respectively connected to the two water spray pipes. The water guide groove has two side ends, and the two side ends of the water guide groove respectively match the positions of the two branch pipes.

6. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: The branch pipe is connected to the water spray pipe via a turning joint.

7. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: The piston side has an axially extending convex strip, the inner side of the cylinder shell is provided with a convex strip groove matching the convex strip, and the convex strip is slidably assembled in the convex strip groove.

8. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: A first abutting ring is provided at the right end of the cylinder shell, a step surface is provided at the middle portion of the piston, and the left and right ends of the elastic member abut against the step surface of the piston and the first abutting ring respectively.

9. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: A second abutting ring located on the left side of the piston is fixedly connected to the inner side of the cylinder shell. When the left end of the piston abuts against the cylinder shell, the side end of the water guide groove is completely staggered with the branch pipe.

10. The solar photovoltaic power generation device with self-cleaning function according to claim 1, characterized in that: The displacement frame has two groups of rollers distributed upper and lower on the side facing the photovoltaic panel, and the upper and lower groups of rollers are respectively in contact with the upper and lower ends of the photovoltaic panel. Among the upper and lower groups of rollers, at least one group has more than 1 roller, and the first driving mechanism is used to drive at least one of the rollers to rotate.

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