Charging pile flexible power supply distribution box assembly replacing relay

Abstract

The invention relates to the technical field of power electronic components, in particular to a charging pile flexible power distribution box assembly replacing a relay, which comprises a shell, a power plug is fixedly connected to one side of the shell, a plugging frame is arranged on the power plug, a positioning mechanism is rotatably connected to the plugging frame, and a storage cover is arranged on one side of the plugging frame. A storage cover is arranged in the shell, a transmission mechanism is rotatably connected to one side of the storage cover, a protective cover is arranged on one side of the transmission mechanism, a box cover is rotatably connected to an opening in the front end of the shell, and a transmission shaft is arranged above the box cover. The charging pile flexible power supply distribution box assembly has the advantages that the power supply plug is automatically pulled out through the plugging frame instead of manual operation, errors or negligence in the manual plugging process is eliminated, the condition of incomplete plugging or misoperation is avoided, the risk of electrical accidents is reduced, and the maintenance efficiency, the safety and the reliability of the charging pile flexible power supply distribution box assembly can be obviously improved.

Description

Technical Field

[0001] This invention relates to the field of power electronic components technology, and in particular to a flexible power distribution box assembly for a charging pile that replaces a relay. Background Technology

[0002] In smart grids, to meet the ever-increasing fast-charging demands of new energy vehicles, current mainstream charging pile power distribution systems generally employ a large number of intermediate relays (or contactors) as actuators. These relays are hard-wired to establish a fixed physical connection path between the charging module and the charging port, ensuring a stable and efficient power supply for new energy vehicles. The technical solution is roughly as follows: the control system issues commands based on charging demand, driving the coils of specific relays to engage, closing their contacts, thereby connecting a power supply loop from the power module to the output port. In this context, the manufacturing of power electronic components plays a crucial role, especially the charging module and its internal power electronic components. Charging modules typically contain several important power electronic components, such as power semiconductor devices (e.g., MOSFETs, IGBTs), rectifiers, capacitors, and inductors. These components regulate and convert electrical energy, ensuring a stable and efficient power output.

[0003] The power connection method for the flexible power distribution box assembly of the charging pile can vary depending on the specific equipment design, but the following common connection methods are usually adopted: 1. DC power input Battery Pack Connection: For energy storage systems, the power distribution box is typically connected to the mains power source via a battery pack. The battery pack provides DC power to the power distribution box. The battery terminals may be directly connected to the input terminals of the power distribution box via cables.

[0004] 2. AC power input AC power connection: Some charge pile systems may use AC power, especially when energy needs to be drawn from the grid. In this case, the power distribution box will be connected to the AC power source via an AC plug or hard-wired terminals.

[0005] Existing flexible power distribution boxes for recharge stacks typically require power disconnection during maintenance to ensure operator safety and prevent electrical accidents. However, current technology necessitates manual unplugging of the AC connector for power disconnection, which is inconvenient for automated disconnection during maintenance. This manual plugging / unplugging process can lead to operator negligence, resulting in incomplete unplugging or accidental plugging into other power ports, increasing the risk of electrical accidents. This is especially problematic when the recharge stack is operating at high voltage and high power; any operational error could result in electric shock or other electrical accidents.

[0006] In summary, the existing technology lacks a technique for automatically disconnecting the power supply to the flexible power distribution box assembly of the charging pile during maintenance. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the prior art by proposing a flexible power distribution box assembly for a charging pile that can replace relays.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a flexible power distribution box assembly for a charging pile that replaces a relay, comprising a housing, a power plug fixedly connected to one side of the housing, a plug-in bracket provided on the power plug, a positioning mechanism rotatably connected to the plug-in bracket, a storage cover provided on one side of the plug-in bracket, a transmission mechanism rotatably connected to one side of the storage cover, a protective cover provided on one side of the transmission mechanism, a box cover rotatably connected to the front opening of the housing, and a transmission shaft provided above the box cover.

[0009] Preferably, one end of the plug-in bracket is fixedly connected to an electric push rod, the other end of the electric push rod is fixedly connected to the inner wall of the housing, a transmission rod is fixedly connected to the side of the plug-in bracket connected to the electric push rod, and a push head is fixedly connected to the bottom end of the plug-in bracket.

[0010] Preferably, the positioning mechanism includes a threaded rod, which is rotatably connected to the inner wall of the bottom end of the plug-in bracket. A U-shaped frame is threadedly connected to the outer wall of the threaded rod, and the U-shaped frame is slidably fitted to the inner wall of the plug-in bracket. Positioning blocks are fixedly connected to both ends of the U-shaped frame, and the positioning blocks are adapted to the outer wall of the power plug.

[0011] Preferably, the storage cover is fixedly connected to the outer shell, a sponge sleeve is fixedly connected to the bottom opening of the storage cover, the sponge sleeve is slidably in contact with the power cord of the power plug, a sliding groove is provided below the opening on one side of the storage cover, a sliding strip is fixedly connected to the bottom of the protective cover, the sliding strip is slidably engaged with the inner wall of the sliding groove, and a fixing rack is fixedly connected to the inner wall on one side of the storage cover.

[0012] Preferably, the transmission mechanism includes a transmission rack, which is slidably connected to the inner wall of the storage cover. A plurality of springs are fixedly connected to the inner end of the transmission rack, and the other end of the springs is fixedly connected to the inner wall of the storage cover. An inclined contact block is fixedly connected to the inner end of the transmission rack, and the inclined contact block is slidably contacted with the push head.

[0013] Preferably, an adjusting wheel is engaged with one side of the outer end of the transmission rack, the adjusting wheel is rotatably connected to the outer wall of the storage cover, a swing rod is fixedly connected to the adjusting wheel, and a push column is fixedly connected to the other end of the swing rod.

[0014] Preferably, a universal joint A is rotatably connected through one side of the inner wall of the protective cover. One end of the universal joint A extends through the inner wall of the protective cover to the outside and is fixedly connected to a transmission wheel. The transmission wheel meshes with a fixed rack for transmission. A bidirectional lead screw is fixedly connected to the other end of the universal joint A. Both ends of the bidirectional lead screw are threadedly connected to moving blocks. A connecting rod is rotatably connected to the moving blocks. A socket baffle is rotatably connected between the other ends of the two connecting rods. A toggle groove is opened on one side of the protective cover. The inner wall of the toggle groove is slidably fitted with one end of the push column.

[0015] Preferably, the drive shaft is rotatably connected to the inner wall of the housing, the outer wall of the drive shaft is provided with a spiral groove, the inner wall of the spiral groove is slidably engaged with the outer wall of the push head, and a drive wheel is fixedly connected to one end of the drive shaft.

[0016] Preferably, a universal joint B is fixedly connected to one end of the box cover, and the universal joint B is rotatably connected to the inner wall of the outer shell. A driven wheel is fixedly connected to the other end of the universal joint B, and the driven wheel is engaged with the driving wheel for transmission.

[0017] Compared with the prior art, the present invention has the following beneficial effects: By setting up a plug-in rack, the power plug can be automatically unplugged before the flexible power distribution box assembly of the charging pile needs to be inspected, eliminating errors or negligence in the manual plugging and unplugging process, avoiding incomplete plugging or unplugging or misoperation, and reducing the risk of electrical accidents. At the same time, by setting up a positioning mechanism on the plug-in rack, it can be positioned according to the shape of the power plug, ensuring that the power plug can be accurately aligned with the socket during the insertion or removal of the power plug, avoiding the deviation between the power plug and the socket, which can significantly improve the maintenance efficiency, safety and reliability of the flexible power distribution box assembly of the charging pile. By setting a drive shaft, the cover of the flexible power distribution box assembly of the charging pile can be automatically opened and closed while the power plug is plugged in and out of the plug-in rack. This further optimizes the safety, efficiency and user experience of the flexible power distribution box assembly of the charging pile, and also improves the reliability and intelligence of the system. The automated opening and closing mechanism effectively avoids errors in manual operation, ensures the safety protection of electrical components, and improves the overall operational safety and maintenance efficiency of the equipment. By incorporating a protective cover and a storage cover, the power plug is unplugged and retracted into the storage cover via a transmission mechanism. Simultaneously, the protective cover automatically seals one opening of the storage cover, protecting the internal power plug. At the same time, the socket baffle on the protective cover automatically moves to cover the power socket. This automatic sealing and covering function provides multiple layers of protection against dust and water for the power plug and socket, while reducing operational errors and equipment maintenance. The flexible power distribution box assembly of the charging pile not only improves safety and convenience but also enhances the equipment's durability, neatness, and intelligence. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention, in use. Figure 2 This is a partial cross-sectional view of the overall structure of the flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention, during maintenance. Figure 3 This is a schematic diagram of the plug-in bracket structure of a flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention. Figure 4 This is a schematic diagram of the positioning mechanism structure of a flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention. Figure 5 This is a partial cross-sectional schematic diagram of the storage cover structure of a flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention. Figure 6 This is a schematic diagram of the transmission mechanism structure of a flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention. Figure 7 This is a schematic diagram showing the unfolded protective cover structure of a flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention. Figure 8 This is a schematic diagram of the cover and drive shaft structure of a flexible power distribution box assembly for a charging pile that replaces a relay, according to the present invention.

[0019] The diagram shows: 1. Outer shell; 2. Power plug; 3. Plug-in holder; 4. Positioning mechanism; 5. Storage cover; 6. Transmission mechanism; 7. Protective cover; 8. Box lid; 9. Drive shaft; 301. Electric actuator; 302. Transmission rod; 303. Push head; 401. Threaded rod; 402. U-shaped frame; 403. Positioning block; 501. Sponge sleeve; 502. Slide groove; 503. Fixed rack; 601. Transmission gear. 602. Spring; 603. Inclined contact block; 604. Adjusting wheel; 605. Swing rod; 606. Push column; 701. Sliding bar; 702. Universal joint A; 703. Transmission wheel; 704. Double-acting screw; 705. Moving block; 706. Connecting rod; 707. Socket baffle; 708. Actuating groove; 901. Helical groove; 902. Driving wheel; 801. Universal joint B; 802. Driven wheel. Detailed Implementation

[0020] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0021] like Figures 1-8 The diagram shows a flexible power distribution box assembly for a charging pile that can replace a relay. It includes a housing 1, a power plug 2 fixedly connected to one side of the housing 1, a plug-in bracket 3 on the power plug 2, a positioning mechanism 4 rotatably connected to the plug-in bracket 3, a storage cover 5 on one side of the plug-in bracket 3, a transmission mechanism 6 rotatably connected to one side of the storage cover 5, a protective cover 7 on one side of the transmission mechanism 6, a box cover 8 rotatably connected to the front opening of the housing 1, and a transmission shaft 9 on top of the box cover 8.

[0022] like Figure 3 As shown, an electric actuator 301 is fixedly connected to one end of the plug-in holder 3, and the other end of the electric actuator 301 is fixedly connected to the inner wall of the outer casing 1. A transmission rod 302 is fixedly connected to the side of the plug-in holder 3 connected to the electric actuator 301, and a push head 303 is fixedly connected to the bottom end of the plug-in holder 3. The transmission rod 302 drives the transmission shaft 9, and the push head 303 drives the transmission mechanism 6.

[0023] like Figure 4 As shown, the positioning mechanism 4 includes a threaded rod 401, which is rotatably connected to the inner wall of the bottom end of the plug-in bracket 3. A U-shaped bracket 402 is threadedly connected to the outer wall of the threaded rod 401. The U-shaped bracket 402 is slidably fitted to the inner wall of the plug-in bracket 3. Positioning blocks 403 are fixedly connected to both ends of the U-shaped bracket 402. The positioning blocks 403 are adapted to the outer wall of the power plug 2.

[0024] By setting up the plug-in rack 3, the power plug 2 can be automatically unplugged before the flexible power distribution box assembly of the charging pile needs to be inspected, eliminating errors or negligence in the manual plugging and unplugging process, avoiding incomplete plugging or unplugging or misoperation, and reducing the risk of electrical accidents. At the same time, by setting up the positioning mechanism 4 on the plug-in rack 3, the power plug can be positioned according to its shape, ensuring that the power plug 2 can be accurately aligned with the socket during insertion or removal, avoiding deviation between the power plug 2 and the socket, which can significantly improve the maintenance efficiency, safety and reliability of the flexible power distribution box assembly of the charging pile.

[0025] like Figure 5 As shown, the storage cover 5 is fixedly connected to the outer shell 1. A sponge sleeve 501 is fixedly connected to the bottom opening of the storage cover 5, and the sponge sleeve 501 is in sliding contact with the power cord of the power plug 2. A groove 502 is provided below the opening on one side of the storage cover 5. A slider 701 is fixedly connected to the bottom of the protective cover 7, and the slider 701 is slidably engaged with the inner wall of the groove 502. A fixing rack 503 is fixedly connected to the inner wall on one side of the storage cover 5. The sponge sleeve 501 reduces the friction between the power cord of the power plug 2 and the storage cover 5.

[0026] like Figure 6 As shown, the transmission mechanism 6 includes a transmission rack 601, which is slidably connected to the inner wall of the storage cover 5. Multiple springs 602 are fixedly connected to the inner end of the transmission rack 601, and the other end of each spring 602 is fixedly connected to the inner wall of the storage cover 5. An inclined contact block 603 is fixedly connected to the inner end of the transmission rack 601, and the inclined contact block 603 is in slidable contact with the push head 303. The springs 602 enable the automatic reset of the transmission rack 601.

[0027] An adjusting wheel 604 is engaged with one side of the outer end of the transmission rack 601. The adjusting wheel 604 is rotatably connected to the outer wall of the storage cover 5. A swing rod 605 is fixedly connected to the adjusting wheel 604, and a push column 606 is fixedly connected to the other end of the swing rod 605.

[0028] like Figure 7 As shown, a universal joint A702 is rotatably connected through one side of the inner wall of the protective cover 7. One end of the universal joint A702 extends through the inner wall of the protective cover 7 to the outside and is fixedly connected to a transmission wheel 703. The transmission wheel 703 meshes with a fixed rack 503 for transmission. A two-way lead screw 704 is fixedly connected to the other end of the universal joint A702. Both ends of the two-way lead screw 704 are threadedly connected to moving blocks 705. A connecting rod 706 is rotatably connected to the moving blocks 705. A socket baffle 707 is rotatably connected between the other ends of the two connecting rods 706. A toggle groove 708 is opened on one side of the protective cover 7. The inner wall of the toggle groove 708 is slidably fitted with one end of the push column 606.

[0029] like Figure 8 As shown, the drive shaft 9 is rotatably connected to the inner wall of the outer casing 1. The outer wall of the drive shaft 9 has a spiral groove 901. The inner wall of the spiral groove 901 is slidably fitted with the outer wall of the push head 303. One end of the drive shaft 9 is fixedly connected to a drive wheel 902.

[0030] like Figure 8 As shown, a universal joint B801 is fixedly connected to one end of the cover 8. The universal joint B801 is rotatably connected to the inner wall of the outer shell 1. A driven wheel 802 is fixedly connected to the other end of the universal joint B801. The driven wheel 802 is engaged with the driving wheel 902 for transmission.

[0031] Working principle: When it is necessary to inspect the outer shell 1 of the flexible power distribution box assembly of the charging pile, the electric push rod 301 drives the connected plug-in bracket 3 to move, so that the plug-in bracket 3 can pull the power plug 2 out of the power socket. While the power plug 2 is retracted into the storage cover 5, the transmission rod 302 on the plug-in bracket 3 slides in the spiral groove 901, causing the transmission shaft 9 to rotate. When the transmission shaft 9 rotates, it can drive the driven wheel 802 to rotate through the drive wheel 902, so that the driven wheel 802 can drive the box cover 8 connected to the universal joint B801 to open automatically for inspection. When the power plug 2 is fully retracted into the storage cover 5 and continues to move, the push head 303 at the bottom of the plug-in bracket 3 will contact and press the inclined contact block 603, causing the inclined contact block 603 to drive the connected transmission rack 601 to move, so that the transmission rack 601 can drive the adjusting wheel 604 to rotate, so that the adjusting wheel 604 can drive the swing rod 605 to rotate, so that the swing rod 605 slides in the toggle groove 708 through the push column 606, thereby driving the protective cover 7 to move and seal the opening on one side of the storage cover 5. When the protective cover 7 moves, the fixed rack 503 causes the transmission wheel 703 to drive the connected universal joint A702 to rotate, which in turn drives the connected double-acting screw 704 to rotate. The double-acting screw 704 then drives the two moving blocks 705 to move, which in turn drives the socket baffle 707 connected to the connecting rod 706 to move, so that the socket baffle 707 can block the power socket.

[0032] The core of this invention lies in replacing the traditionally densely deployed group of intermediate relays with a combined system of a "relay board" and a "flexible distribution module." This system, acting as an intelligent distribution hub between the DC bus inside the charging pile and multiple charging output ports, consists of a relay board. This board is the basic connection layer, integrating a streamlined number of high-capacity, high-performance DC contactors K1, K2, ... Kn. These contactors are primarily used to establish or disconnect the main connection between the total output of the charging module and the flexible distribution module, and to provide safe electrical isolation during system maintenance and failures. Compared to traditional solutions, their number is significantly reduced.

[0033] Connection relationship: The input terminal is directly connected to the positive terminal (+) and negative terminal (-) of the DC bus of the charging pile; the output terminal is connected to the input terminal of the flexible distribution module.

[0034] Flexible Power Distribution Module: Composition: This module is the core of flexible intelligent power distribution and consists of multiple parallel intelligent power distribution units. Each intelligent power distribution unit is essentially a solid-state switching circuit based on a fully controlled semiconductor switching device, and integrates a drive circuit, current sensor, temperature sensor, and isolated communication interface.

[0035] Connection relationship: Its input terminal is connected in parallel to the output terminal of the relay board; its output terminal is connected to each charging output port respectively. Each power distribution unit can independently and controllably connect its connected port to the DC bus or disconnect it from the bus.

[0036] Intelligent control system: A main controller PCU communicates with the relay board and each power distribution unit via a high-speed communication CAN bus, collects voltage, current and temperature information in real time, and issues control commands.

[0037] Flexible power allocation in normal operating mode: The intelligent control system calculates the optimal power allocation strategy based on charging order requirements. First, the main contactor on the control relay board closes, drawing DC bus power to the flexible allocation module. Then, the control system sends precise switching commands to the target power allocation module, driving the corresponding semiconductor switches to conduct at high speed, accurately allocating power to the requesting charging port.

[0038] Mode Switching and Fault Handling: When a large amount of power needs to be allocated to a port, the system can control multiple power distribution modules to simultaneously supply power to that port, achieving power aggregation. If a power distribution module fails, the system can immediately shut down that circuit and report an alarm, while simultaneously scheduling other normal power distribution modules to continue operating, ensuring overall system availability. When maintenance is required, the main circuit is disconnected via a relay board to ensure no power is supplied to the downstream devices, ensuring safety and reliability.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A flexible power distribution box assembly for a charging pile that replaces a relay, comprising a housing (1), characterized in that: A power plug (2) is fixedly connected to one side of the outer shell (1). A plug-in bracket (3) is provided on the power plug (2). A positioning mechanism (4) is rotatably connected to the plug-in bracket (3). A storage cover (5) is provided on one side of the plug-in bracket (3). A transmission mechanism (6) is rotatably connected to one side of the storage cover (5). A protective cover (7) is provided on one side of the transmission mechanism (6). A box cover (8) is rotatably connected to the front opening of the outer shell (1). A transmission shaft (9) is provided above the box cover (8).

2. The flexible power distribution box assembly for a charging pile that replaces a relay according to claim 1, characterized in that: One end of the plug-in bracket (3) is fixedly connected to an electric push rod (301), and the other end of the electric push rod (301) is fixedly connected to the inner wall of the outer shell (1). A transmission rod (302) is fixedly connected to the side of the plug-in bracket (3) connected to the electric push rod (301), and a push head (303) is fixedly connected to the bottom end of the plug-in bracket (3).

3. The flexible power distribution box assembly for a charging pile that replaces a relay according to claim 1, characterized in that: The positioning mechanism (4) includes a threaded rod (401), which is rotatably connected to the inner wall of the bottom end of the plug-in bracket (3). A U-shaped bracket (402) is threadedly connected to the outer wall of the threaded rod (401), and the U-shaped bracket (402) is slidably fitted to the inner wall of the plug-in bracket (3). Positioning blocks (403) are fixedly connected to both ends of the U-shaped bracket (402), and the positioning blocks (403) are adapted to the outer wall of the power plug (2).

4. The flexible power distribution box assembly for a charging pile that replaces a relay according to claim 1, characterized in that: The storage cover (5) is fixedly connected to the outer shell (1). A sponge sleeve (501) is fixedly connected to the bottom opening of the storage cover (5). The sponge sleeve (501) is slidably contacted with the power cord of the power plug (2). A sliding groove (502) is provided below the opening on one side of the storage cover (5). A sliding strip (701) is fixedly connected to the bottom of the protective cover (7). The sliding strip (701) is slidably engaged with the inner wall of the sliding groove (502). A fixing rack (503) is fixedly connected to the inner wall on one side of the storage cover (5).

5. The charging pile flexible power distribution box assembly that replaces relays according to claim 2, characterized in that: The transmission mechanism (6) includes a transmission rack (601), which is slidably connected to the inner wall of the storage cover (5). Multiple springs (602) are fixedly connected to the inner end of the transmission rack (601), and the other end of the springs (602) is fixedly connected to the inner wall of the storage cover (5). An inclined contact block (603) is fixedly connected to the inner end of the transmission rack (601), and the inclined contact block (603) is slidably contacted with the push head (303).

6. The charging pile flexible power distribution box assembly as an alternative to a relay according to claim 5, characterized in that: The transmission rack (601) has an adjusting wheel (604) meshing on one side of its outer end. The adjusting wheel (604) is rotatably connected to the outer wall of the storage cover (5). A swing rod (605) is fixedly connected to the adjusting wheel (604), and a push column (606) is fixedly connected to the other end of the swing rod (605).

7. The charging pile flexible power distribution box assembly as an alternative to a relay according to claim 6, characterized in that: A universal joint A (702) is rotatably connected through one side of the inner wall of the protective cover (7). One end of the universal joint A (702) extends through the inner wall of the protective cover (7) to the outside and is fixedly connected to a transmission wheel (703). The transmission wheel (703) meshes with a fixed rack (503) for transmission. A two-way screw (704) is fixedly connected to the other end of the universal joint A (702). Both ends of the two-way screw (704) are threadedly connected to a moving block (705). A connecting rod (706) is rotatably connected to the moving block (705). A socket baffle (707) is rotatably connected between the other ends of the two connecting rods (706). A toggle groove (708) is opened on one side of the protective cover (7). The inner wall of the toggle groove (708) is slidably engaged with one end of the push column (606).

8. The charging pile flexible power distribution box assembly that replaces relays according to claim 2, characterized in that: The drive shaft (9) is rotatably connected to the inner wall of the outer casing (1). The outer wall of the drive shaft (9) is provided with a spiral groove (901). The inner wall of the spiral groove (901) is slidably engaged with the outer wall of the push head (303). One end of the drive shaft (9) is fixedly connected to a drive wheel (902).

9. A flexible power distribution box assembly for a charging pile that replaces a relay, as described in claim 8, characterized in that: One end of the box cover (8) is fixedly connected to a universal joint B (801), which is rotatably connected to the inner wall of the outer shell (1). The other end of the universal joint B (801) is fixedly connected to a driven wheel (802), which meshes with the driving wheel (902) for transmission.

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