Motor with built-in speed change device

Abstract

The invention relates to a motor with a built-in speed change device, and relates to the technical field of motors, the motor comprises a motor body, a shell of the motor body is composed of a hub shell, a front cover and a rear cover, a built-in driver is installed in the motor body, a shaft rod penetrating out of the front cover is arranged in the motor body, a front bearing is arranged in the front cover, a rear bearing is arranged in the rear cover, and the hub shell is connected with the hub shell. The hub comprises a hub shell, a rear bearing and a built-in driver, the built-in driver is mounted in the rear bearing, the bevel gear planetary reducer is arranged in the hub shell, and the bevel gear planetary reducer adopts a first-stage planetary reduction structure to improve the reduction ratio, an IPM built-in magnetic steel rotor structure is adopted, self-developed motor optimization design software is combined, reluctance torque is effectively utilized, and the speed reduction ratio of the hub shell is improved. Meanwhile, a double-layer built-in driver is integrated in the rear bearing, and a first-stage bevel gear planetary speed reduction structure is matched, so that the high speed reduction ratio and large torque output are realized, the size of the assembly is greatly reduced, and the overall weight is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more particularly to a motor with a built-in speed change device. Background Technology

[0002] In emerging equipment fields such as wheeled robots, electric wheelchairs, and intelligent mobility scooters, hub motors, as core power components, directly determine the operating efficiency, spatial adaptability, and user experience of these devices. However, current mainstream hub motors generally suffer from multi-dimensional technical bottlenecks, making it difficult to meet the comprehensive requirements of these devices for "compact structure, strong power, and stable operation."

[0003] Most hub motors use surface-mounted magnet rotors, resulting in low reluctance torque utilization and low power density. This means the motor occupies a large space but cannot output torque matching the equipment's load requirements. Furthermore, the motor controller is often a separate, independent unit, requiring additional installation space and wiring harness connections. This not only makes the motor assembly bulky and heavy but also increases overall energy consumption. Especially for battery-powered portable equipment, an excessively heavy power module significantly shortens the driving range. In addition, design flaws in existing hub motors further limit their application scenarios. For example, some products lack integrated parking brake functionality, rendering them ineffective in complex environments such as slopes and bumpy roads. The current method of achieving stable stopping poses safety hazards. Even the few products that integrate braking components mostly adopt an external design, which not only occupies extra space but is also susceptible to damage from external impacts. On the other hand, insufficient noise control and protection performance are prominent issues: traditional gear transmission structures are crudely designed and prone to generating high-frequency noise during operation, seriously affecting the user experience. The housing sealing structure is rudimentary, often relying on a single sealing ring or simple gap sealing, resulting in low protection levels. The root cause of these problems lies in the fact that existing designs have failed to achieve deep integration of the motor, reducer, controller, and brake, and lack collaborative optimization in material selection and heat dissipation design. Based on this, a motor with a built-in speed change device is proposed here. Summary of the Invention

[0004] To overcome the problems existing in related technologies, the present invention provides a motor with a built-in speed change device. By adopting an IPM built-in magnet rotor structure, the reluctance torque is effectively utilized to increase the motor torque and maximum power. At the same time, the dual-layer built-in driver is integrated into the rear bearing, and with the help of a single-stage helical planetary reduction structure, a high reduction ratio and high torque output are achieved while the assembly volume is greatly reduced and the overall weight is effectively reduced.

[0005] To achieve the above objectives, the present invention provides a motor with a built-in speed change device, comprising a motor body, the outer casing of which is composed of a hub housing, a front cover, and a rear cover. An internal driver and an IPM motor are installed within the motor body, and a shaft extends through the front cover. A front bearing is located within the front cover, and a rear bearing is located within the rear cover. The internal driver is installed within the rear bearing. The invention also includes: The helical planetary reducer is located inside the hub housing and adopts a single-stage planetary reduction structure to improve the reduction ratio. The helical planetary reducer includes a sun gear, an internal gear ring, and three planetary gears. The rotation of the three planetary gears drives the internal gear ring, the hub housing, and the front cover to rotate synchronously. The planetary gears have built-in ball bearings. A sealing element is used to seal the hub housing with the front cover and the rear cover.

[0006] The planetary gear has a mounting cavity, the ball bearing is installed in the mounting cavity, and the port of the mounting cavity has an integrally formed protrusion.

[0007] Preferably, it also includes an electromagnetic brake, which is mounted on the rear cover via a connecting plate and sealed inside the motor body by the rear cover.

[0008] Preferably, it also includes a planetary carrier for mounting a helical planetary reducer, and the outer end of the built-in driver is provided with a pressure cap, which has a plurality of mounting holes.

[0009] Preferably, the sealing element includes a first sealing ring, a second sealing ring, a third sealing ring, and a fourth sealing ring, wherein the first sealing ring is disposed between the front bearing and the front cover, and the second sealing ring is disposed between the rear bearing and the rear cover.

[0010] Preferably, the rear cover has an inwardly recessed mounting groove, and the bottom end of the mounting groove has a mounting cavity.

[0011] Preferably, the back cover has an air guide groove inside, one end of which is connected to the mounting cavity, and the inner wall of the mounting groove has multiple air outlets that are connected to the air guide groove. The back cover has a one-way exhaust hole that allows only gas to be discharged.

[0012] Preferably, it also includes linkage components, air outlet components, and air guide channels; The linkage is connected to the shaft drive; The air guide channel is located inside the housing of the motor body, and its air outlet end is at least connected to the air guide groove. The air outlet is driven by the linkage, and when the shaft rotates, it sends external air into the motor body through the air guide channel.

[0013] Preferably, the front cover has a heat dissipation component inside, which is used to reduce the temperature of the planetary gears.

[0014] Preferably, the heat sink includes a plurality of first heat sink fins, which are arranged in a ring array inside the front cover.

[0015] Preferably, the heat sink includes a plurality of second heat sink fins arranged in a ring array inside the front cover, and third heat sink fins are symmetrically arranged on both sides of the second heat sink fins. The distance between the third heat sink fins and the second heat sink fins gradually increases from the end closer to the planetary gear to the end farther from the planetary gear. A phase change element is provided between the third heat sink fins and the second heat sink fins. The phase change component includes a heat-conducting shell, inside which a phase change block is provided, and on both sides of the heat-conducting shell are heat-equalizing plates.

[0016] The technical solution provided by this invention may include the following beneficial effects: 1. In this invention, by adopting an IPM built-in magnet rotor structure and combining it with self-developed motor optimization design software, the reluctance torque is effectively utilized to increase the motor torque and maximum power. At the same time, the dual-layer built-in driver is integrated into the rear bearing, and with the single-stage helical gear planetary reduction structure, a high reduction ratio and high torque output are achieved while the assembly volume is significantly reduced and the overall weight is effectively reduced, perfectly adapting to the space and weight-sensitive needs of wheeled robots, electric wheelchairs and other equipment.

[0017] 2. In this invention, the planetary gears are made of high-strength plastic material and the helical gear design is optimized to reduce motor operating noise and improve user experience. Through multi-dimensional sealing design, such as O-ring seals between the hub and the front and rear covers, epoxy glue potting at the cable outlet, and electromagnetic brake sealing inside the motor, the motor protection level reaches IP56, effectively resisting rain and dust intrusion, preventing internal component burnout, and significantly improving the reliability and service life of the motor in complex environments.

[0018] 3. In this invention, a heat dissipation component is provided inside the front cover. The heat of the planetary gear can be directly conducted through the first heat dissipation fins in the annular array; or a design with the second heat dissipation fins and the third heat dissipation fins on both sides can be adopted. The fins near the end of the planetary gear are more densely distributed, which enhances the heat dissipation coverage of the key heat source area, quickly removes the conventional heat generated by the gear operation, and avoids the temperature from being too high and affecting the performance of the component.

[0019] 4. In this invention, a phase change element is set between the second and third heat dissipation fins. The phase change block inside melts and absorbs a large amount of heat, effectively suppressing the rapid temperature rise under high load and protecting the gears and lubricating oil. When the temperature drops, the phase change block solidifies and releases heat. Combined with the heat spreader plates on both sides of the heat-conducting shell, heat is evenly transferred and diffused, avoiding local high temperature. Through intelligent thermal management of conventional heat dissipation and phase change buffering, the temperature changes during frequent start-stop or load fluctuations are smoothed, maintaining the long-term efficient operation of the motor and expanding its application in high-load industrial transmission scenarios.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0021] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts in the exemplary embodiments of the invention.

[0022] Figure 1 This is a three-dimensional appearance structure diagram of the present invention; Figure 2 This is a front view structural diagram of the present invention; Figure 3 This is the present invention. Figure 2 Sectional view along the middle AA direction; Figure 4 This is a schematic diagram of the structure of the back cover of the present invention; Figure 5 This is a schematic diagram of the hub housing, helical gear planetary reducer, and planetary carrier of the present invention in their installed state; Figure 6 This is a schematic diagram of the built-in magnet rotor structure of the IPM motor of the present invention; Figure 7 This is a schematic diagram of the structure of the rear cover and the helical planetary reducer of the present invention; Figure 8 This is a schematic diagram of the planetary gear structure of the present invention; Figure 9 This is a schematic diagram of the structure of the back cover, the built-in driver, and the pressure cover of the present invention; Figure 10 This is a schematic diagram of the structure of the front cover and the first heat dissipation fin of the present invention; Figure 11 This is a schematic diagram of the structure of the front cover, the second heat dissipation fin, and the third heat dissipation fin of the present invention; Figure 12 This is a schematic diagram of the phase change element of the present invention; Figure 13 This is a cross-sectional structural schematic diagram of the phase change component of the present invention.

[0023] The correspondence between the labels and component names in the attached figures is as follows: 1. Motor body; 101. Hub housing; 102. Front cover; 103. Rear cover; 1031. One-way exhaust port; 104. Shaft; 105. Mounting groove; 106. Mounting cavity; 2. Front bearing; 3. Built-in driver; 4. IPM motor; 5. Helical planetary reducer; 51. Sun gear; 52. Planetary gear; 53. Ball bearing; 54. Mounting cavity; 55. Protrusion; 56. Internal gear ring; 6. Electromagnetic brake; 7. Connecting spline; 8. Seal; 81. First sealing ring; 82. Second sealing ring; 83. Third sealing ring; 84. Fourth sealing ring; 9. Rear bearing; 10. Air outlet; 11. Air guide groove; 12. Planetary carrier; 13. Pressure cap; 14. Mounting hole; 15. Heat sink; 151. First heat sink fin; 152. Second heat sink fin; 153. Third heat sink fin; 154. Phase change element; 1541. Thermally conductive shell; 1542. Heat spreader; 1543. Phase change block. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention. Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. Although preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the invention more thorough and complete, and to fully convey the scope of the invention to those skilled in the art.

[0025] The technical solutions of the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] Example 1: See Figures 1-9As shown, this invention proposes a motor with a built-in speed change device, including a motor body 1. The outer shell of the motor body 1 adopts a split structure, consisting of a hub shell 101, a front cover 102, and a rear cover 103. A connecting spline 7 is provided between the hub shell 101 and the rear cover 103. A mounting groove 105 is formed by an inward recess on the rear cover 103, and a mounting cavity 106 is opened at the bottom of the mounting groove 105. A built-in driver 3 and an IPM motor 4 are installed inside the motor body 1, and a shaft 104 is provided that extends from the front cover 102. The built-in driver 3 can be designed as a double-layer structure to improve the control integration. The IPM motor 4 is located inside the hub shell 101, as shown in the figure. Figure 8 As shown, the IPM motor 4 adopts an IPM built-in magnet rotor structure. Electromagnetic optimization is performed using the company's independently developed motor optimization design software, PovoMotorDesigner, effectively utilizing reluctance torque to improve the motor's torque density while enhancing the safety and reliability of the magnets. A front bearing 2 (model 6201-2RS) is located inside the front cover 102, and a rear bearing 9 (model 16010-2RS) is located inside the rear cover 103. Their excellent sealing and rotational accuracy effectively reduce friction and wobble of the shaft 104 during rotation, ensuring stable power output. The built-in driver 3 is installed inside the rear bearing 9, fully utilizing axial space and improving overall space utilization. The outer side of the built-in driver 3 is equipped with… The pressure cover 13 has multiple mounting holes 14 for easy fixing and wiring. A sealing element 8 is provided between the hub housing 101 and the front cover 102 and the rear cover 103. The sealing element 8 includes a first sealing ring 81, a second sealing ring 82, a third sealing ring 83 and a fourth sealing ring 84. The first sealing ring 81 is located between the front bearing 2 and the front cover 102, the second sealing ring 82 is located between the rear bearing 9 and the rear cover 103, the third sealing ring 83 is located at the joint between the hub housing 101 and the rear cover 103, and the fourth sealing ring 84 is located at the joint between the hub housing 101 and the front cover 102. Multiple seals form a multi-layered sealing protection. This multi-layered sealing protection design effectively prevents external dust, moisture and other contaminants from entering the motor.

[0027] An air guide groove 11 is provided inside the rear cover 103. The air guide groove 11 can be a ring structure. One end of the air guide groove 11 is connected to the mounting cavity 106. The inner wall of the mounting groove 105 is provided with multiple air outlets 10 that are connected to the air guide groove 11. The rear cover 103 is provided with a one-way exhaust hole 1031 that only allows gas to be discharged.

[0028] The motor also integrates a helical planetary reducer 5, located inside the hub housing 101. This reducer adopts a single-stage planetary reduction structure, achieving a high single-stage reduction ratio through optimized gear parameters. The helical gear helix angle in the helical planetary reducer 5 is designed to be 15–25°, suitable for applications requiring high-speed and high-stability transmission, helping to improve transmission efficiency and operational smoothness. The helical planetary reducer 5 specifically includes a sun gear 51, an internal gear ring 56, and three planetary gears 52. When the IPM motor 4 is running, it drives the sun gear 51, which in turn drives the three planetary gears 52 to rotate. The rotation of the three planetary gears 52 drives the internal gear ring 56, the hub housing 101, the hub inside the hub housing 101, and the front cover 102 to rotate synchronously. The planetary gears 52 are made of high-strength materials. Made of high-strength engineering plastics, this design effectively reduces operating noise while meeting torque output requirements. The planetary gears 52 feature a weight-reduction optimized design, minimizing overall weight while maintaining structural strength, which helps improve the dynamic response performance of the motor. This reduction structure can increase the motor's output torque by approximately 30%, reduce noise by 10-12 dB, and increase maximum power by more than 50%. Each planetary gear 52 has an internal mounting cavity 54 containing a built-in 608 type ball bearing 53. The mounting cavity 54 has an integrally formed protrusion 55 at its port to improve bearing positioning accuracy and load-bearing capacity, and extend service life. The internal gear ring 56 and the planetary gears 52 use helical gear meshing, resulting in smooth transmission and high precision, effectively improving the reduction ratio and achieving a smooth reduction in speed and a significant increase in torque.

[0029] Planetary carrier 12 is provided around the helical planetary reducer 5. The planetary carrier 12 adopts a weight-reduction and optimization design to install and protect the internal gears and bearings of the reducer and reduce the intrusion of external impurities. In addition, the motor also integrates an electromagnetic brake 6. The electromagnetic brake 6 is installed on the rear cover 103 through a connecting plate and sealed inside the motor body 1 by the rear cover. The lead cable is led out through the cable outlet hole on the connecting plate and sealed with epoxy glue, which has good dustproof and waterproof performance. The built-in design of the electromagnetic brake 6 not only improves the overall space utilization, but also makes the braking torque greater and the braking more reliable, which is suitable for applications with frequent start and stop or requiring precise positioning.

[0030] Example 2: See Figure 3 and Figure 10 As shown, this embodiment is an extension of Example 1: a heat sink 15 is provided inside the front cover 102. The heat sink 15 can reduce the temperature of the planetary gear 52 to a certain extent, which is intended to specifically solve the problem of gear temperature rise caused by high load operation. In particular, when the planetary gear 52 is made of engineering plastics (such as PEEK, nylon, etc.), it can effectively avoid the mechanical property degradation phenomena such as modulus reduction, creep aggravation and fatigue life reduction of the material at high temperature, thereby ensuring the long-term reliability and durability of the transmission system.

[0031] The heat sink 15 includes a plurality of first heat sink fins 151, which are arranged in a ring array inside the front cover 102, with one end of the first heat sink fins 151 close to the planetary gear 52.

[0032] Example 3: See Figure 3 as well as Figures 11-13 As shown, this embodiment differs from Embodiment 2 in that the heat sink 15 includes multiple second heat sink fins 152 arranged in a ring array inside the front cover 102. Third heat sink fins 153 are symmetrically arranged on both sides of the second heat sink fins 152. The spacing between the third heat sink fins 153 and the second heat sink fins 152 is designed to gradually increase from the end closer to the planetary gear 52 to the end farther away from the planetary gear 52, forming a non-uniform distribution structure. This layout makes the heat sink fins more dense in the area near the gear, thereby enhancing the heat dissipation coverage of the critical heat source area. To further improve the heat dissipation effect, some fins can also be designed to have a higher height on the side closer to the gear, or extend to a position close to the gear through a heat-conducting plate, forming an efficient thermal bridge to ensure that heat can be quickly transferred from the gear to the heat dissipation structure. At the same time, it is necessary to avoid interfering with the normal rotation of the front cover 102. A phase change element 154 is provided between the third heat sink fins 153 and the second heat sink fins 152. The phase change element 154 includes a heat-conducting outer shell 1541, inside which a phase change block 1543 is disposed. Both sides of the heat-conducting outer shell 1541 are provided with heat spreaders 1542. The heat spreaders 1542 can be replaced with micro heat pipes according to actual application requirements to enhance the lateral heat diffusion capability. The phase change block 1543 is made of a material that can undergo a phase change within the typical operating temperature range of gears (e.g., 60–80°C), such as paraffin wax, which has the characteristic of absorbing or releasing a large amount of latent heat during the transition between solid and liquid states.

[0033] As described above, in actual use, when the planetary gear 52 generates a large amount of heat due to sudden high load operation, the heat is rapidly conducted through the third heat dissipation fin 153 and the second heat dissipation fin 152, while the phase change block 1543 inside the heat-conducting shell 1541 absorbs heat during the melting process, effectively suppressing the rapid rise in temperature, thereby protecting the gear and its gear lubricating oil from overheating damage. After the load is reduced or the system is shut down, the temperature gradually decreases, the phase change material re-solidifies, and the stored heat is released, which is transferred through the heat-conducting shell 1541 to the third heat dissipation fin 153 and the second heat dissipation fin 152, and finally slowly dissipated into the surrounding environment through the motor shell.

[0034] The heat generated by the planetary gear 52 is initially concentrated at the base of the heat dissipation fins, which can easily form local high-temperature points. The heat spreader 1542 can spread this concentrated heat laterally, so that it evenly covers the surface of the heat-conducting shell 1541 of the phase change element 154. This ensures that the internal phase change block 1543 can be heated synchronously and as a whole, avoiding the inefficient situation where only some areas melt while other areas remain solid. This maximizes the utilization of the thermal absorption potential of the phase change material. Furthermore, between the third heat dissipation fin 153 and the second heat dissipation fin 152, the heat spreader 1542 acts as a lateral heat transfer channel, allowing heat not only to be transferred outward from the gear end, but also to be quickly redistributed in the dense fin array. This guides the heat to more and farther heat dissipation fins to participate in heat dissipation, enhancing the heat dissipation capacity and temperature uniformity of the entire front cover 102 structure.

[0035] By upgrading the traditional motor housing from a single heat dissipation function to an intelligent thermal management module with thermal energy buffering and regulation capabilities, the temperature fluctuations of the planetary gear 52 under frequent start-stop or drastic load changes can be effectively smoothed, improving system thermal stability and component lifespan. It is suitable for electric drive systems and industrial transmission scenarios with high thermal management requirements.

[0036] The present invention has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have their own emphasis; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. Those skilled in the art should also understand that the actions and modules involved in the specification are not necessarily essential to the present invention. Furthermore, it is understood that the steps in the method of the embodiments of the present invention can be adjusted, combined, and deleted according to actual needs, and the structure in the device of the embodiments of the present invention can be combined, divided, and deleted according to actual needs.

[0037] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A motor with a built-in speed change device, comprising a motor body (1), wherein the outer casing of the motor body (1) is composed of a hub casing (101), a front cover (102), and a rear cover (103), wherein a built-in driver (3) and an IPM motor (4) are installed inside the motor body (1), and a shaft (104) extending from the front cover (102) is provided, characterized in that, The front cover (102) is provided with a front bearing (2), the rear cover (103) is provided with a rear bearing (9), the built-in driver (3) is installed in the rear bearing (9), and further includes: The helical planetary reducer (5) is located inside the hub housing (101), and the helical planetary reducer (5) adopts a single-stage planetary reduction structure to improve the reduction ratio. The helical planetary reducer (5) includes a sun gear (51), an internal gear ring (56) and three planetary gears (52). The three planetary gears (52) rotate to drive the internal gear ring (56), the hub housing (101) and the front cover (102) to rotate synchronously. The planetary gears (52) have ball bearings (53) built in them. The hub housing (101) is sealed with the front cover (102) and the rear cover (103) by the sealing element (8); The front cover (102) is provided with a heat sink (15) inside, which is used to reduce the temperature of the planetary gear (52); The heat sink (15) includes a plurality of second heat sink fins (152), which are arranged in a ring array inside the front cover (102). Third heat sink fins (153) are symmetrically arranged on both sides of the second heat sink fins (152). The spacing between the third heat sink fins (153) and the second heat sink fins (152) is designed to gradually increase from the end closer to the planetary gear (52) to the end farther away from the planetary gear (52). A phase change element (154) is provided between the third heat sink fins (153) and the second heat sink fins (152). The phase change element (154) includes a heat-conducting shell (1541), inside which a phase change block (1543) is provided, and on both sides of the heat-conducting shell (1541) are heat-equalizing plates (1542).

2. The motor with a built-in speed change device according to claim 1, characterized in that, The planetary gear (52) has an installation cavity (54) inside, and the ball bearing (53) is installed in the installation cavity (54). The port of the installation cavity (54) has an integrally formed protrusion (55).

3. The motor with a built-in speed change device according to claim 1, characterized in that, It also includes an electromagnetic brake (6), which is mounted on the rear cover (103) via a connecting plate and sealed inside the motor body (1) via the rear cover.

4. The motor with a built-in speed change device according to claim 1, characterized in that, It also includes a planetary carrier (12) for mounting a helical planetary reducer (5), and the outer end of the built-in driver (3) is provided with a pressure cap (13) with a plurality of mounting holes (14).

5. The motor with a built-in speed change device according to claim 1, characterized in that, The sealing element (8) includes a first sealing ring (81), a second sealing ring (82), a third sealing ring (83) and a fourth sealing ring (84). The first sealing ring (81) is located between the front bearing (2) and the front cover (102), and the second sealing ring (82) is located between the rear bearing (9) and the rear cover (103).

6. The motor with a built-in speed change device according to claim 1, characterized in that, The rear cover (103) has an indented mounting groove (105), and the bottom end of the mounting groove (105) has a mounting cavity (106).

7. The motor with a built-in speed change device according to claim 6, characterized in that, The back cover (103) has an air guide groove (11) inside. One end of the air guide groove (11) is connected to the mounting cavity (106). The inner wall of the mounting groove (105) has multiple air outlets (10) that are connected to the air guide groove (11). The back cover (103) has a one-way exhaust hole (1031) that allows only gas to be discharged.

Images