Range extender generator shell structure and design method

Abstract

The invention discloses a range extender generator shell structure, which comprises an inner shell and an outer shell, a cooling flow channel is arranged between the inner shell and the outer shell, the outer shell comprises an independent shell wall and a connecting disc, the connecting disc is connected with the bottom surface of the shell wall, the shell wall is provided with a controller mounting hole of a range extender and a plurality of whole vehicle threaded interfaces, and the whole vehicle threaded interfaces are connected with the controller mounting hole of the range extender. The whole vehicle threaded connector is used for installing the range extender generator on a whole vehicle. A range extender engine connecting and mounting interface is arranged on the side surface of the connecting disc; the shell wall and the connecting disc are two independent parts, the shell wall can be shared when different engines are carried, only the connecting disc connected with the engine needs to be newly developed, the development period is shortened, and the development cost is reduced; the bearing mounting hole, the oil seal mounting hole and the range extender engine connecting and mounting interface are arranged on the outer shell, the inner shell is provided with matching interfaces as few as possible, the outer shell can be designed according to carrying requirements of different whole vehicles, the inner shell is shared, the development cost can be reduced, and the development period can be shortened.

Description

Technical Field

[0001] The invention relates to the field of range extender water-cooled generator housing design, and in particular to a range extender generator housing structure and a generator housing design method. Background Art

[0002] The range extender is an additional energy storage component installed on pure electric vehicles to increase the mileage of pure electric vehicles. The working principle of the electric vehicle range extender generator is to use a small engine, usually gasoline, to drive the generator to generate electricity. The generated electricity can directly drive the electric vehicle's motor or charge the electric vehicle's battery. When the electric vehicle battery is low on power, the range extender can start working and provide a continuous supply of electricity, allowing the electric vehicle to continue driving, solving the problem of the electric vehicle running out of power halfway. The range extender usually includes components such as an engine, a generator, an inverter, and a controller system.

[0003] With the rapid development of the new energy vehicle industry, the market size of extended-range vehicles is showing a trend of continuous expansion. In the design of the range extender, due to the different layout and envelope requirements of different new energy vehicles, as well as different power requirements, there are differences between the generator system and its components, and the versatility and interchangeability of the components are poor. This is mainly reflected in the different requirements for axial space and external interfaces, and the design of the motor housing cannot be universal. In terms of cost, the overall cost of the generator system is mainly composed of components such as the stator and rotor assembly, motor housing, motor end cover, and junction box cover. Generally speaking, the mold opening cost of the motor housing accounts for about 70%-75% of the overall mold cost of the electric drive system, and the design and mold opening process of the motor housing usually occupies 20-30% of the entire electric drive project development cycle.

[0004] The existing range extender generator housing design structure and method have problems such as poor generator system platform versatility, poor component interchangeability and a long development cycle. Summary of the invention

[0005] The purpose of the present invention is to provide a range extender generator housing structure and a platform-based generator housing design method to solve the problems of poor platform versatility, poor component interchangeability and long development cycle of existing generator systems.

[0006] To achieve the above objectives, the technical solution of the present invention is:

[0007] A range extender generator housing structure comprises an inner housing and an outer housing, a cooling channel is arranged between the inner housing and the outer housing, the outer housing comprises an independent housing wall and a connecting plate, the connecting plate is connected to the bottom surface of the housing wall, the housing wall is provided with a range extender controller mounting hole and a plurality of vehicle threaded interfaces, the vehicle threaded interfaces are used to install the range extender generator on the vehicle; a range extender engine connection mounting interface is arranged on the side of the connecting plate.

[0008] Furthermore, an inner assembly positioning stop is provided on the bottom surface of the shell wall, and an outer assembly positioning stop is provided on the connecting disk. The outer assembly positioning stop is circumferentially arranged on the upper surface of the connecting disk, and the outer assembly positioning stop extends into the inner assembly positioning stop to connect the shell wall and the connecting disk.

[0009] Furthermore, a plurality of lugs are arranged on the side of the connection plate, and the range extender engine connection and mounting interface is arranged on the lugs.

[0010] Furthermore, a rear end cover assembly stop is provided at the top end of the inner shell body, and a plurality of rear end cover mounting holes are evenly spaced circumferentially on the top surface of the shell wall, the rear end cover includes a convex stop and a cover plate, the convex stop is circumferentially arranged along the bottom surface of the cover plate, and a plurality of mounting holes are spaced apart on the cover plate, when the inner shell body is placed in the inner cavity of the outer shell body, the convex stop of the rear end cover is located in the rear end cover assembly stop, the cover plate included in the rear end cover covers the top end opening of the outer shell body, the mounting holes on the cover plate correspond one by one to the mounting holes of the rear end cover, the bolts pass through the mounting holes on the cover plate and the mounting holes of the rear end cover in sequence, the rear end cover is mounted on the outer shell body, and the stator is sealed through the rear end cover.

[0011] Furthermore, the middle part of the bottom surface of the connecting plate is a bearing mounting hole, and an oil seal mounting hole for installing an oil seal is provided on the chassis. The oil seal mounting hole is integrally connected with the bearing mounting hole. The motor shaft passes through the oil seal mounting hole and the bearing mounting hole to drive the motor to work, and the oil seal surrounds the outer periphery of the motor shaft.

[0012] Furthermore, the mold of the outer shell includes four independent sliders, namely an upper slider, a right slider, a lower slider and a left slider. The bottom surface of each slider includes a groove, and the groove is adapted to the shape of the motor outer shell. After the four sliders are assembled together, they surround the outer shell. One side of each slider is connected to the cylinder. When the four sliders surround the outer shell, the cylinder pushes the four sliders tightly, and the groove of each slider is close to the outer wall of the outer shell.

[0013] Furthermore, the cooling channel is provided with a water channel reserved rib. When the water channel reserved rib is removed, the end of the coolant flowing in the cooling channel is toward the front end of the vehicle. When the water channel reserved rib is retained, the end of the coolant flowing in the cooling channel is toward the rear end of the vehicle.

[0014] A method for designing a range extender generator housing includes:

[0015] The shell wall and the connecting plate of the outer shell are designed as two independent parts;

[0016] An assembly positioning inner stop is arranged on the bottom surface of the shell wall, and an assembly positioning outer stop is arranged on the connecting disk. The assembly positioning outer stop is arranged circumferentially on the upper surface of the connecting disk, and the assembly positioning outer stop extends into the assembly positioning inner stop to connect the shell wall and the connecting disk;

[0017] The controller mounting hole of the range extender and multiple vehicle threaded interfaces are designed on the shell wall;

[0018] The bearing mounting hole is arranged in the middle of the bottom surface of the connecting plate, and the oil seal mounting hole on the connecting plate is connected with the bearing mounting hole in an integrated manner;

[0019] The range extender engine connection and mounting interface is arranged on the side of the connection plate;

[0020] The mold of the outer shell is designed as four independent sliders, and the bottom surface of each slider includes a groove, which is matched with the shape of the motor outer shell. After the four sliders are assembled together, they surround the outer periphery of the outer shell.

[0021] The beneficial effects of the present invention are:

[0022] 1. In the present invention, the outer shell includes a shell wall and a connecting plate at the bottom of the shell wall. The shell wall and the connecting plate are two independent components. The shell wall and the connecting plate are positioned and installed by an assembly positioning inner stopper and an assembly positioning outer stopper and then welded into one. When different engines are installed, the shell wall can be shared. Only a new connecting plate connected to the engine needs to be developed, thereby reducing the development cycle and development cost.

[0023] 2. In the present invention, the bearing mounting holes, oil seal mounting holes, and range extender engine connection mounting interfaces are arranged on the outer shell, and the inner shell is designed with as few matching interfaces as possible. The outer shell can be designed according to the mounting requirements of different vehicles, while the inner shell is shared to reduce development costs and development cycles.

[0024] 3. In the present invention, the outer shell mold of the generator is divided into four independent sliders. When the vehicle interface, that is, the threaded interface of the whole vehicle, is different, only one slider that matches the threaded interface of the whole vehicle needs to be changed, and the other three sliders are universal, which can achieve maximum sharing of the mold and reduce the project development cycle and development costs.

[0025] 4. In the present invention, water channel reserved ribs are arranged on the cooling channel, and the water channel reserved ribs are arranged between the two lowest layers of water channel ribs. The flow path of the coolant can be changed by retaining or removing the water channel reserved ribs. If the water channel reserved ribs are processed and removed, the end of the coolant flow is located at the front end of the vehicle, which can meet the water outlet layout requirements of the front end of the vehicle; if the water channel reserved ribs are retained, the end of the coolant flow is located at the rear end of the vehicle, which can meet the water outlet layout requirements of the rear end of the vehicle, thereby meeting the needs of different vehicles to share the mold, reducing the mold opening cost and project cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a finished product design case of a generator housing of the present invention.

[0027] Figure 2 It is a schematic diagram of a design case of the inner casing and outer casing of the generator of the present invention.

[0028] Figure 3 It is a schematic diagram of a design case of a generator housing and a connecting plate of the present invention.

[0029] Figure 4 It is a schematic diagram of a generator housing parting design case of the present invention.

[0030] Figure 5 It is a schematic diagram of a generator housing parting design case of the present invention.

[0031] Figure 6 It is a schematic diagram of a generator inner casing water channel design case of the present invention.

[0032] Among them: finished motor housing 1; inner housing 2; rear end cover assembly stop 2-1; stator assembly surface 2-2; water channel rib 2-3; assembly tool positioning hole 2-4; starting end 2-5; water channel reserved rib 2-6; outer housing 3; shell wall 4; inner housing mating surface 4-1; rear end cover mounting hole 4-2; water inlet hole 4-3; water outlet hole 4-4; controller mounting hole 4-5; vehicle threaded interface 4-6; assembly positioning inner stop 4-7; connecting plate 5; assembly positioning outer stop 5-1, range extender engine connection mounting interface 5-2; bearing mounting hole 5-3; oil seal mounting hole 5-4; upper slider 6; right slider 7; lower slider 8; left slider 9. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] The range extender generator housing of the present invention is as follows Figure 1 As shown, Figure 1 The finished generator housing 1 comprises an inner housing 2 and an outer housing 3 of the generator. The upper and lower ends of the inner housing 2 and the outer housing 3 are connected by friction welding. A cooling channel for coolant to flow is provided between the inner housing 2 and the outer housing 3 of the generator.

[0035] like Figure 2As shown, the top of the inner housing 2 is provided with a rear end cover assembly stop 2-1, which is used for stator sealing, and the cavity inside the inner housing 2 is used to accommodate the motor stator. The inner wall of the inner housing 2 is the stator assembly surface 2-2, and the motor stator is installed in the cavity of the inner housing 2 by a shrink fit process. In the present invention, the inner housing has a certain thickness, and the top surface of the inner housing 2 is provided with a rear end cover assembly stop 2-1, and the rear end cover assembly stop 2-1 is a concave stop or a groove.

[0036] The outer wall of the inner shell 2 is provided with multiple layers of water channel ribs 2-3 from top to bottom, the water channel ribs 2-3 protrude from the outer wall of the inner shell 2, and the inner side of the water channel ribs 2-3 is provided on the outer wall of the inner shell 2. When the inner shell 2 and the outer shell 3 are welded together, the outer side of the water channel ribs is closely attached to the inner wall of the outer shell 3. The inner shell 2, the multiple layers of water channel ribs 2-3, and the outer shell 3 form a continuous cooling water channel.

[0037] An assembly tool positioning hole 2-4 is set on the inner shell 2, and the assembly tool positioning hole 2-4 is a groove set on the bottom surface of the inner shell 2. When the inner shell 2 is assembled into the cavity inside the outer shell 3, the inner shell 2 is first placed on a workbench, and a pin is set on the workbench. The pin extends into the assembly tool positioning hole 2-4 to limit the inner shell 2 to limit the posture of the inner shell 2, and then the inner shell 2 is grasped by a robot arm and placed into the cavity inside the outer shell 3.

[0038] The outer shell 3 includes a shell wall 4 and a connection plate 5 connected to the shell wall 4 . The shell wall 4 and the connection plate 5 are two independent components. The connection plate 5 is the bottom surface of the outer shell 3 , and the connection plate 5 is connected to the bottom surface of the shell wall 4 .

[0039] The inner wall of the shell wall 4 is the inner shell mating surface 4 - 1 , and a continuous cooling water channel is formed between the inner shell mating surface 4 - 1 and the outer wall of the inner shell 2 .

[0040] The top surface of the shell wall 4 is evenly spaced along the circumferential direction to form a plurality of rear end cover mounting holes 4-2. A plurality of lugs may be provided on the upper end of the side surface of the shell wall 4, the top surface of the lugs being flush with the top surface of the shell wall 4, and the rear end cover mounting holes 4-2 passing through the top and bottom surfaces of the lugs. The rear end cover comprises a convex stop and a cover plate, the convex stop being provided along the circumferential direction of the bottom surface of the cover plate, the cover plate being spaced apart with a plurality of mounting holes, the mounting holes on the cover plate corresponding to the rear end cover mounting holes 4-2 one by one. When the inner shell 2 is placed in the inner cavity of the outer shell 3, the convex stop of the rear end cover is located in the rear end cover assembly stop 2-1 on the top end of the inner shell 2, the end of the cover plate included in the rear end cover covers the top end opening of the outer shell, the mounting holes on the cover plate corresponding to the rear end cover mounting holes 4-2 one by one, the bolts pass through the mounting holes on the cover plate and the rear end cover mounting holes 4-2 in sequence, the rear end cover is mounted on the outer shell 3, and the stator is sealed through the rear end cover.

[0041] The shell wall 4 is provided with a coolant inlet hole 4-3 and a coolant outlet hole 4-4. The motor inlet hole 4-3 and the motor outlet hole 4-4 are used for the coolant to enter and exit. The positions of the inlet hole 4-3 and the coolant outlet hole 4-4 on the shell wall can be adjusted according to the requirements of the whole vehicle. The shell wall 4 is also provided with a controller mounting hole 4-5 of the range extender and a plurality of vehicle threaded interfaces 4-6. The plurality of vehicle threaded interfaces 4-6 are respectively connected to the structures on the vehicle such as the bracket, water pipe, pump, etc. on the vehicle, so as to install the range extender generator on the vehicle through the vehicle threaded interface 4-6. A plurality of lugs are arranged at intervals on the shell wall 4. The controller mounting hole 4-5 and the vehicle threaded interface 4-6 are arranged on the lugs. The position and shape of the lugs are designed according to the installation requirements of the vehicle.

[0042] The middle part of the bottom surface of the connecting plate 5 is a bearing mounting hole 5-3, and the motor shaft passes through the bearing mounting hole 5-3 to drive the motor to work. The chassis 5 is provided with an oil seal mounting hole 5-4 for mounting an oil seal, and an oil seal is installed at the oil seal mounting hole 5-4 to prevent water and dust from entering the motor cavity. The connecting plate 5 has a certain thickness, and the oil seal mounting hole 5-4 is located on the surface of the connecting plate 5, or protrudes from the surface of the connecting plate 5. The oil seal mounting hole 5-4 is connected with the bearing mounting hole 5-3 in one piece, and the motor shaft passes through the oil seal mounting hole 5-4 and the bearing mounting hole 5-3 to drive the motor to work, and the oil seal is sealed around the outer periphery of the motor shaft.

[0043] In the present invention, the inner housing is designed with as few matching interfaces as possible, and the range extender engine connection installation interface 5-2, the bearing installation hole 5-3 and the oil seal installation hole 5-4 are arranged on the outer housing. This preferred solution can design the outer housing according to different loading requirements, while the inner housing is shared to reduce development costs and development cycles.

[0044] The bottom surface of the shell wall 4 is provided with an assembly positioning inner stop 4-7. The connection disk 5 is provided with an assembly positioning outer stop 5-1, which is circumferentially arranged on the upper surface of the connection disk 5. The range extender engine connection and installation interface 5-2 is arranged on the side of the connection disk 5. A plurality of lugs can be arranged on the side of the connection disk 5, and the range extender engine connection and installation interface 5-2 is arranged on the lug. The shape of the lug and the position of the lug on the side of the connection disk 5 can be determined according to the installation requirements. The shell wall 4 and the connection disk 5 are welded together after being positioned and installed by the assembly positioning inner stop 4-7 and the assembly positioning outer stop 5-1. In this preferred embodiment, the shell wall 4 is shared when different engines are mounted, and only the connection disk 5 connected to the engine needs to be newly developed, which reduces the development cycle and development cost.

[0045] like Figure 4 and Figure 5As shown, the demolding direction of the outer shell 3 is designed into four directions. The molds for the four demolding directions are four independent sliders, namely, an upper slider 6, a right slider 7, a lower slider 8, and a left slider 9. The bottom surface of each slider includes an arc-shaped groove, and the groove is adapted to the shape of the motor outer shell. During the casting process, the four sliders are assembled together and surround the outer periphery of the outer shell 3. One side of each slider is connected to the cylinder. When the four sliders surround the outer periphery of the outer shell 3, the four sliders are pressed tight by the cylinder so that the groove of each slider is close to the outer wall of the outer shell 3. According to the difference of the vehicle mounting interface, that is, the whole vehicle threaded interface 4-6, only one of the sliders can be changed. In one embodiment of the present invention, the left slider 9 on the shell wall 4 that matches the surface where the whole vehicle threaded interface 4-6 is located is changed, and the remaining sliders are shared. In the present invention, the motor outer shell mold is divided into four independent sliders. When the vehicle interface, that is, the whole vehicle threaded interface 4-6, is different, only one of the sliders needs to be changed, and the other three sliders are universal, so as to achieve maximum sharing of the mold and reduce the project development cycle and development costs.

[0046] like Figure 6 As shown, a cooling channel is provided on the outer surface of the inner shell 2 of the generator, and the cooling channel includes a plurality of water channel ribs 2-3. The cooling channel includes a starting end 2-5 for the flow of coolant and an end for the flow of coolant. The starting end 2-5 cooperates with the water inlet hole 4-3, and the end cooperates with the water outlet hole 4-4. The coolant flows in from the water inlet hole 4-3 and then starts to flow from the starting end 2-5. After the coolant flows to the end, it flows out from the water outlet hole 4-4. The positions of the water inlet hole 4-3 and the water outlet hole 4-4 on the outer shell 3 can be designed according to cooling requirements. In a preferred embodiment, a water channel reserved rib 2-6 can be provided on the cooling channel, and the water channel reserved rib 2-6 is provided between the bottom two layers of water channel ribs 2-3. The flow path of the coolant can be changed by retaining or removing the water channel reserved rib 2-6, such as Figure 6 As shown in the figure, if the water channel reserved ribs 2-6 are removed, the end of the coolant flow is at Figure 6 At point A in the figure, the position of point A faces the front end of the vehicle, which can meet the water outlet layout requirements of the front end of the vehicle. If the water channel reserved ribs 2-6 are retained, the end of the coolant flow is at Figure 6 At point B in the figure, the position of point B is toward the rear end of the vehicle, which can meet the water outlet layout requirements of the rear end of the vehicle. This preferred solution can meet the needs of different vehicles to share molds, reducing mold opening costs and project cycles.

[0047] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper" and "lower" indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

Claims

1. A range extender generator housing structure, comprising an inner housing (2) and an outer housing (3), wherein a cooling channel is provided between the inner housing (2) and the outer housing (3), wherein: The outer shell (3) comprises an independent shell wall (4) and a connecting plate (5), wherein the connecting plate (5) is connected to the bottom surface of the shell wall (4), and the shell wall (4) is provided with a range extender controller mounting hole (4-5) and a plurality of vehicle threaded interfaces (4-6), wherein the vehicle threaded interfaces (4-6) are used to mount the range extender generator on the vehicle; and a range extender engine connection mounting interface (5-2) is provided on the side of the connecting plate (5).

2. A range extender generator housing structure according to claim 1, characterized in that: The bottom surface of the shell wall (4) is provided with an assembly positioning inner stop (4-7), and the connecting disk (5) is provided with an assembly positioning outer stop (5-1). The assembly positioning outer stop (5-1) is arranged along the circumferential direction on the upper surface of the connecting disk (5), and the assembly positioning outer stop (5-1) extends into the assembly positioning inner stop (4-7) to connect the shell wall (4) and the connecting disk (5).

3. The range extender generator housing structure according to claim 1, characterized in that: A plurality of lugs are arranged on the side of the connection plate (5), and the range extender engine connection and installation interface (5-2) is arranged on the lugs.

4. The range extender generator housing structure according to claim 1, characterized in that: The top end of the inner shell (2) is provided with a rear end cover assembly stop (2-1).

5. The range extender generator housing structure according to claim 1, characterized in that: The top surface of the shell wall (4) is provided with a plurality of rear end cover mounting holes (4-2) evenly spaced along the circumferential direction, the rear end cover comprises a convex stop and a cover plate, the convex stop is circumferentially provided along the bottom surface of the cover plate, the cover plate is provided with a plurality of mounting holes at intervals, when the inner shell (2) is placed in the inner cavity of the outer shell (3), the convex stop of the rear end cover is located in the rear end cover assembly stop (2-1), the rear end cover comprises a cover plate covering the top end opening of the outer shell, the mounting holes on the cover plate correspond to the rear end cover mounting holes (4-2) one by one, bolts are passed through the mounting holes on the cover plate and the rear end cover mounting holes (4-2) in sequence, the rear end cover is mounted on the outer shell (3), and the stator is sealed through the rear end cover.

6. The range extender generator housing structure according to claim 1, characterized in that: The middle part of the bottom surface of the connecting plate (5) is a bearing mounting hole (5-3).

7. The range extender generator housing structure according to claim 1, characterized in that: An oil seal mounting hole (5-4) for mounting an oil seal is provided on the chassis (5); the oil seal mounting hole (5-4) is integrally connected with the bearing mounting hole (5-3); the motor shaft passes through the oil seal mounting hole (5-4) and the bearing mounting hole (5-3) to drive the motor to work; the oil seal surrounds the outer periphery of the motor shaft.

8. The range extender generator housing structure according to claim 1, characterized in that: The mold of the outer shell (3) includes four independent sliders, namely an upper slider (6), a right slider (7), a lower slider (8) and a left slider (9). The bottom surface of each slider includes a groove, and the groove is adapted to the shape of the motor outer shell. After the four sliders are assembled together, they surround the outer periphery of the outer shell (3). One side of each slider is connected to the cylinder. When the four sliders surround the outer periphery of the outer shell (3), the cylinder presses the four sliders tightly, and the groove of each slider is tightly attached to the outer wall of the outer shell (3).

9. The range extender generator housing structure according to claim 1, characterized in that: The cooling channel is provided with a water channel reserved rib (2-6). When the water channel reserved rib (2-6) is removed, the end of the coolant flowing in the cooling channel faces the front end of the vehicle. When the water channel reserved rib (2-6) is retained, the end of the coolant flowing in the cooling channel faces the rear end of the vehicle.

10. A method for designing a range extender generator housing according to any one of claims 1 to 9, comprising: The shell wall (4) and the connecting plate (5) of the outer shell (3) are designed as two independent components, and the inner shell (2) is located in the cavity of the outer shell (3); An assembly positioning inner stop (4-7) is arranged on the bottom surface of the shell wall (4), and an assembly positioning outer stop (5-1) is arranged on the connecting disk (5). The assembly positioning outer stop (5-1) is arranged along the circumferential direction on the upper surface of the connecting disk (5), and the assembly positioning outer stop (5-1) extends into the assembly positioning inner stop (4-7) to connect the shell wall (4) and the connecting disk (5); A controller mounting hole (4-5) of the range extender and a plurality of vehicle threaded interfaces (4-6) are designed on the shell wall (4); The bearing mounting hole (5-3) is arranged in the middle of the bottom surface of the connecting plate (5), and the oil seal mounting hole (5-4) located on the connecting plate (5) is integrally connected with the bearing mounting hole (5-3); The range extender engine connection and installation interface (5-2) is arranged on the side of the connection plate (5); The mold of the outer shell (3) is designed as four independent sliders, the bottom surface of each slider comprises a groove, the groove is adapted to the shape of the motor outer shell, and the four sliders are assembled together to surround the outer periphery of the outer shell (3).

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