TWI783756B - Bicycle rear hub - Google Patents

Abstract

A bicycle rear hub includes a casing and at least one valve. The casing includes a main part and a flange part. The flange part radially protrudes from the main part. The main part has an accommodation space and at least one connection hole in fluid communication with each other. The flange part has at least one air channel in fluid communication with outside. The air channel is connected to the accommodation space via the connection hole. The valve is movably disposed in the air channel, and the valve has an outer diameter larger than an inner diameter of the connection hole. When the bicycle rear hub is stationary, the gravity forces the valve blocks the connection hole, such that the accommodation space is not in fluid communication with the air channel. When the bicycle rear hub is rotated, a centrifugal force forces the valve to separate from the connection hole, such that the accommodation space is in fluid communication with the air channel.

Description

bicycle rear hub

The invention relates to a rear wheel hub, in particular to a bicycle rear wheel hub.

Common bicycles on the market can be divided into human-driven bicycles, electric bicycles and semi-electric bicycles according to the driving mode. The so-called human-powered bicycle is exactly the bicycle that the rider must step on the pedal and drive the rear wheel through the chain to drive the bicycle forward. As for the electric bicycle, it does not require the rider to step on the pedals, but is completely advanced by the power provided by the motor. Regarding the semi-electric bicycle, it is a combination of the aforementioned two.

In the case of electric or semi-electric bicycles, the motor is usually housed in the hub of the bicycle wheel. In order to prevent water from entering the hub and damaging the motor, there is a certain degree of demand for the sealing of the housing of the hub, but such a requirement will also cause the problem that it is difficult to balance the heat dissipation effect of the motor. Therefore, on the premise of preventing water from entering the hub, how to take into account the heat dissipation effect on the motor is a problem that researchers in this field are working on solving.

The present invention is to provide a rear wheel hub of a bicycle, which can take into account the heat dissipation effect on the motor under the premise of preventing water from entering the wheel hub.

A bicycle rear hub disclosed in an embodiment of the present invention includes a casing and at least one valve element. The casing includes a main body and a flange. The flange portion protrudes from the main body along the radial direction of the main body, and the main body has an accommodating space and at least one communicating hole connected thereto. The flange portion has at least one gas channel connected to the outside, and the gas channel is connected to the accommodating space through the communication hole. The valve part is movably arranged in the gas passage, and the outer diameter of the valve part is larger than the inner diameter of the communication hole. When the rear wheel hub of the bicycle is stationary, the valve member is blocked the communication hole by the action of gravity, so that the accommodation space is not connected to the gas channel. When the rear wheel hub of the bicycle rotates, the centrifugal force acting on the valve part separates the valve part from the communication hole, so that the accommodating space communicates with the outside through the gas channel.

According to the bicycle rear hub disclosed in the above-mentioned embodiments, the valve member is movably arranged in the gas passage, and its outer diameter is larger than the inner diameter of the communication hole connecting the gas passage and the accommodation space, so that when the bicycle rear hub is stationary, The valve part is blocked by gravity to block the communication hole, so that the accommodating space is not connected to the gas channel, and when the rear hub of the bicycle rotates, the valve part is separated from the communication hole through the centrifugal force acting on the valve part, so that the accommodating space can pass through the gas The channel is connected to the outside. Thereby, it can be ensured that when the rear hub of the bicycle is stationary, water will not enter the accommodation space and damage the motor assembly in the accommodation space, and when the motor assembly operates to rotate the rear hub of the bicycle, external air can enter the accommodation space. The motor assembly dissipates heat.

The above description of the content of the present invention and the following description of the implementation are used to demonstrate and explain the principle of the present invention, and provide further explanation of the patent application scope of the present invention.

1, 1a, 1b: bicycle rear hub

2: Rear flywheel assembly seat

10: shell

11: Main body

111: The first shell

1111: ring wall

1112: side wall

1113: end face

1114: Inner wall surface

1115: threaded structure

1116: Connecting hole

1117b: Annular groove

1118b: bottom surface

1119b: side wall

112: the second shell

1121: board body

1121b: ring bump

1122: Assembly column

1123: threaded structure

113:Accommodating space

12, 13: flange part

121, 131: the first surface

122, 132: the second surface

123: end face

124, 133: assembly holes

125: gas channel

1251: first channel

12511: first paragraph

12512: second paragraph

12513: the third paragraph

12514: opening

1252:Second channel

1253a: The third channel

20: Valve

30: shaft

40: plug body

41: Board

42: Insertion Department

D1: outer diameter

D2, D3, D4, D5: inner diameter

Fig. 1 is a schematic perspective view of a bicycle rear hub according to a first embodiment of the present invention.

FIG. 2 is an exploded schematic view of FIG. 1 .

FIG. 3 is a partially enlarged and exploded schematic diagram of FIG. 2 .

FIG. 4 is a schematic partial cross-sectional view of FIG. 1 .

FIG. 5 is a partially enlarged schematic cross-sectional view of FIG. 4 .

FIG. 6 is another partially enlarged schematic cross-sectional view of FIG. 4 .

FIG. 7 is a partially enlarged cross-sectional schematic view of the rear hub of the bicycle in FIG. 5 when it is rotating.

Fig. 8 is a partially enlarged cross-sectional schematic view of the rear hub of a bicycle according to the second embodiment of the present invention.

FIG. 9 is a partially enlarged cross-sectional schematic view of the rear hub of the bicycle in FIG. 8 when it is rotating.

Fig. 10 is a partially enlarged cross-sectional schematic view of a bicycle rear hub according to a third embodiment of the present invention.

Please refer to FIG. 1 . FIG. 1 is a schematic perspective view of a bicycle rear hub according to a first embodiment of the present invention. FIG. 2 is an exploded schematic diagram of FIG. 1 . FIG. 3 is a partially enlarged and exploded schematic diagram of FIG. 2 .

In this embodiment, the bicycle rear hub 1 includes a housing 10 and a plurality of valve parts 20 . The housing 10 includes a main body 11 and a flange 12 . The main body 11 includes a first shell 111 and a second shell 112 assembled together. The first shell 111 includes an annular wall 1111 and a side wall 1112 . The side wall 1112 is connected to one end of the annular wall 1111 in the axial direction of the annular wall 1111 . The annular wall 1111 has an end surface 1113, and the end surface 1113 is located on the other side of the annular wall 1111 relative to the side wall 1112. end. The second shell 112 includes a board 1121 and an assembly column 1122 connected thereto. The assembly column 1122 is installed in the annular wall 1111 , and the board 1121 abuts against the end surface 1113 of the annular wall 1111 . In detail, the annular wall 1111 also has an inner wall 1114 and a thread structure 1115 on the inner wall 1114 , and the assembly column 1122 has a thread structure 1123 . The threaded structure 1123 of the assembly column 1122 is screwed with the threaded structure 1115 of the annular wall 1111, so that the second shell 112 is fixed on the annular wall 1111, and the first shell 111 and the second shell 112 jointly form a housing Space 113. The accommodating space 113 is used for accommodating components such as a motor assembly (not shown), and the motor assembly is used to drive the bicycle rear hub 1 to rotate so that the bicycle can move forward.

In this embodiment, the bicycle rear hub 1 may further include two shafts 30 , and the two shafts 30 are respectively connected to the side wall 1112 of the first shell 111 and the plate 1121 of the second shell 112 . The two shaft rods 30 are respectively used to be installed on the rear fork of the bicycle frame. In addition, the plate body 1121 of the second shell 112 can be used to connect a rear flywheel assembly seat 2, and the rear flywheel assembly seat 2 is used for assembly of a rear flywheel (not shown).

Next, please refer to Figure 3 to Figure 6 . FIG. 4 is a schematic partial cross-sectional view of FIG. 1 . FIG. 5 is a partially enlarged schematic cross-sectional view of FIG. 4 . FIG. 6 is another partially enlarged schematic cross-sectional view of FIG. 4 .

The flange portion 12 of the casing 10 protrudes from the annular wall 1111 along the radial direction of the main body 11 and is adjacent to the side wall 1112 . In this embodiment, the casing 10 may further include another flange portion 13, which also protrudes from the annular wall 1111 along the radial direction of the main body portion 11, and is farther away from the side wall 1112 than the flange portion 12. . The flange portion 12 has a first surface 121 , a second surface 122 , an end surface 123 and a plurality of assembly holes 124 . First The surface 121 and the second surface 122 are opposite to each other in the axial direction of the main body 11 , the end surface 123 is located on one side of the flange portion 12 in the axial direction of the main body 11 , and the end surface 123 connects the first surface 121 and the second surface 122 . The assembling holes 124 are through holes and opposite ends thereof are respectively located on the first surface 121 and the second surface 122 . The flange portion 13 also has a first surface 131 , a second surface 132 and a plurality of assembly holes 133 . The first surface 131 and the second surface 132 are opposite to each other in the axial direction of the main body 11 , the assembly holes 133 are through holes and opposite ends thereof are respectively located on the first surface 131 and the second surface 132 . The assembling holes 133 are used for assembling a plurality of spokes (not shown) connected to the wheel frame.

The flange portion 12 also has a plurality of gas passages 125, the number of which is, for example, twelve and can be divided into four groups. Each group of gas passages 125 is located between two adjacent assembly holes 124 , and the two groups of gas passages 125 are opposite to each other, while the other two groups of gas passages 125 are opposite to each other.

In this embodiment, the annular wall 1111 has a plurality of communication holes 1116 , and these communication holes 1116 are all connected to the accommodating space 113 . Each of these gas passages 125 has a first passage 1251 and a second passage 1252 connected to each other, and the first passage 1251 and the second passage 1252 of each gas passage 125 extend along two different directions respectively, and these first passages 1251 are respectively connected to the accommodating space 113 through the communicating holes 1116 . Since the structures of these gas channels 125 are substantially the same, only the structure of one of the gas channels 125 and the connection relationship between the gas channel 125 and one of the communication holes 1116 will be described in detail below.

In detail, one end of the first channel 1251 is connected to the communication hole 1116, And extend along the radial direction of the main body portion 11 . One end of the second channel 1252 communicates with the first channel 1251 , and extends along the axial direction of the main body portion 11 to connect to the first surface 121 of the flange portion 12 . That is to say, the extending direction of the first channel 1251 is perpendicular to the extending direction of the second channel 1252 . Furthermore, the first channel 1251 has a first segment 12511 , a second segment 12512 and a third segment 12513 . The second section 12512 is located between the first section 12511 and the third section 12513 and communicates with the first section 12511 and the third section 12513. The end of the first section 12511 away from the second section 12512 is connected to the communication hole 1116, and the second channel 1252 is connected. In the second paragraph 12512. In addition, the end of the first channel 1251 away from the communication hole 1116 has an opening 12514 , and the opening 12514 is located on the end surface 123 of the flange portion 12 and communicates with the third section 12513 of the first channel 1251 .

It should be noted that the extending direction of the first channel 1251 is not limited to be perpendicular to the extending direction of the second channel 1252 . In other embodiments, the extending direction of the first channel may form a non-right angle with the extending direction of the second channel. In addition, the second channel is not limited to be connected to the first surface. In other embodiments, the second channel may be connected to the second surface.

These valve elements 20 are, for example, balls. These valve parts 20 are respectively movably arranged in the first passage 1251 of these gas passages 125, and the outer diameter D1 of the valve part 20 is smaller than the inner diameter D2 of the first passage 1251 and larger than the inner diameter D3 of the communication hole 1116, and the second The inner diameter D4 of the second passage 1252 is smaller than the outer diameter D1 of the valve member 20 to prevent the valve member 20 from separating from the second passage 1252 from the gas passage 125 and prevent the valve member 20 from falling into the accommodating space 113 from the communication hole 1116 .

However, the inner diameter D4 of the second passage 1252 of the gas passage 125 does not limited to be smaller than the outer diameter D1 of the valve member 20 . In other embodiments, the inner diameter of the second channel of the gas channel may be equal to or greater than the outer diameter of the valve element, and a stopper structure may be added at the connection between the second channel and the second section of the first channel to prevent the valve element from The gas channel is disengaged from the second channel.

In this embodiment, the bicycle rear hub 1 may further include four plug bodies 40 . These plug bodies 40 are made of flexible materials such as rubber, for example. Each of the plug bodies 40 includes a connected plate portion 41 and three insertion portions 42 . The three insertion portions 42 of each plug body 40 are respectively inserted into the third sections 12513 of the three first passages 1251 from the three openings 12514 of one group of gas passages 125 , and the plate portion 41 abuts against the flange portion 12 end face 123 .

In this embodiment, the setting of the opening 12514 of the first channel 1251 allows the valve member 20 to be installed, and the setting of the plug body 40 inserted into the first channel 1251 from the opening 12514 can prevent the valve member 20 from coming out of the first channel from the opening 12514. Channel 1251. However, in other embodiments, the first channel may have no opening, and the plug body may be omitted, and the valve member may be installed into the first channel through other feasible structures (such as adding an assembly channel communicating with the outside), and After the valve parts are installed, the assembly channel is closed.

The position of the valve member 20 located in the first channel 1251 of the two air channels 125 will be illustrated below when the bicycle is placed on the ground and the bicycle rear hub 1 is stationary. As shown in Figure 5, one of the gas passages 125 is located at the place where the flange portion 12 is farthest from the ground, and under the action of gravity, the different parts of the valve member 20 in the first passage 1251 of the gas passage 125 are respectively located in the communication holes. 1116 and the first section 12511 of the first passage 1251 to block the communication hole 1116, so that the accommodating space 113 is not communicated with the first passage 1251 of the gas passage 125, so it can ensure that the bicycle When the rear hub 1 is stationary, water will not enter the accommodating space 113 through the air channel 125 , and damage to the motor assembly in the accommodating space 113 can be avoided.

As shown in Figure 6, another gas channel 125 is located at the place where the flange part 12 is closest to the ground, and the valve element 20 in the first channel 1251 of the gas channel 125 is separated from the communication hole 1116 by the effect of gravity, and is located in the first channel 1251. The third segment 12513 of the channel 1251. At this time, although the accommodating space 113 can communicate with the outside through the communication hole 1116, the first channel 1251 and the second channel 1252, since the gas channel 125 is located at the place where the flange part 12 is closest to the ground, even if water flows from the second channel 1252 enters the first channel 1251 , the water will not move upward under the action of gravity, and will not enter the accommodating space 113 through the first channel 1251 and the communication hole 1116 .

Next, please refer to FIG. 7 . FIG. 7 is a partially enlarged cross-sectional schematic view of the rear hub of the bicycle in FIG. 5 when it is rotating.

When the motor assembly operates to drive the bicycle rear hub 1 to rotate, the centrifugal force acting on the valve member 20 separates the valve member 20 from the communication hole 1116 and is located in the third section 12513 of the first passage 1251, so that the accommodating space 113 passes through the communication hole 1116 , the first channel 1251 and the second channel 1252 are connected to the outside, so outside air can enter the accommodating space 113 through the second channel 1252 , the first channel 1251 and the communication hole 1116 to dissipate heat from the motor assembly. Moreover, even if water drops on the flange portion 12 during the rotation of the rear wheel hub 1 of the bicycle, the rear wheel hub 1 of the bicycle that is rotating will immediately bounce or shake off the water, so there will be no water flowing from the second channel 1252, the first The channel 1251 and the communicating hole 1116 are not sure about entering the accommodating space 113 .

Therefore, it can be seen from the above that the bicycle rear hub 1 can prevent water from entering On the premise of entering its interior, it can effectively take into account the heat dissipation effect of the motor when the motor assembly is in operation.

It should be noted that the number of the communication hole 1116 , the gas channel 125 and the valve element 20 is not limited to a plurality. In other embodiments, the number of the communicating hole, the gas channel and the valve element can be only one.

In addition, the gas channel 125 is not limited to have the first channel 1251 and the second channel 1252 . In other embodiments, the gas channel may only have the first channel, and the plug body may be omitted. Under such a configuration, the stopper structure can be set on the inner wall of the first passage, and the stopper structure does not fill the gap between the inner wall of the first passage and the valve member, so when the rear hub of the bicycle rotates, it can The valve element is prevented from being thrown out from the opening of the first passage, and at the same time, the accommodating space can be ensured to communicate with the external environment through the communication hole and the first passage.

Next, please refer to FIG. 8 . FIG. 8 is a partially enlarged cross-sectional schematic view of the bicycle rear hub according to the second embodiment of the present invention.

In this embodiment, the bicycle rear hub 1a is similar to the bicycle rear hub 1 described above with reference to FIGS. The differences between the two, the same or similar parts between the two will not be repeated.

In this embodiment, the gas channel 125 further has a third channel 1253a, one end of the third channel 1253a communicates with the second section 12512 of the first channel 1251, and extends in a direction different from the extending direction of the first channel 1251. Extending to the second surface 122 of the flange portion 12 . In detail, the third channel 1253a extends along the axial direction of the main body 11 . The inner diameter D5 of the third channel 1253a is smaller than the outer diameter of the valve member 20 D1, to prevent the valve member 20 from detaching from the gas channel 125 from the third channel 1253a.

However, the inner diameter D5 of the third passage 1253 a of the gas passage 125 is not limited to be smaller than the outer diameter D1 of the valve member 20 . In other embodiments, the inner diameter of the third channel of the gas channel may be equal to or greater than the outer diameter of the valve element, and a stopper structure may be added at the connection between the third channel and the second section of the first channel to prevent the valve element from Disengage the gas channel from the third channel.

Next, please refer to FIG. 9 . FIG. 9 is a partially enlarged schematic cross-sectional view of the rear hub of the bicycle in FIG. 8 when it is rotating.

When the motor assembly operates to drive the bicycle rear hub 1a to rotate, the centrifugal force acting on the valve member 20 causes the valve member 20 to separate from the communication hole 1116 and to be located in the third section 12513 of the first channel 1251, so that the accommodating space 113 passes through the communication hole 1116, the first channel 1251, the second channel 1252 and the third channel 1253a are connected to the outside, so the external air can enter the accommodating space 113 through the second channel 1252, the first channel 1251 and the communication hole 1116, and can pass through the third channel 1253a, the first channel 1251 and the communicating hole 1116 enter the accommodating space 113 to dissipate heat from the motor assembly.

In this embodiment, the design of the third passage 1253a in the air passage 125 can increase the amount of air entering the accommodating space 113 from the external environment when the bicycle rear hub 1a rotates, thereby improving the heat dissipation of the motor assembly. Effect.

Next, please refer to FIG. 10 . FIG. 10 is a partially enlarged cross-sectional schematic view of a rear wheel hub of a bicycle according to a third embodiment of the present invention.

In this embodiment, the bicycle rear hub 1b is similar to the bicycle rear hub 1 described above with reference to FIGS. The structure of the end surface of the shaped wall is different from that of the plate of the second shell, so the following description only focuses on introducing the differences between the two, and the same or similar parts between the two will not be repeated.

In this embodiment, the annular wall 1111 further has an annular groove 1117b, and the annular groove 1117b is formed by being recessed from the end surface 1113 of the annular wall 1111, and the bottom surface 1118b of the annular groove 1117b and the end surface 1113 of the annular wall 1111 are for example The sidewall 1119b of the annular groove 1117b is connected to each other, and the sidewall 1119b of the annular groove 1117b is not perpendicular to the bottom surface 1118b of the annular groove 1117b and the end surface 1113 of the annular wall 1111 . The plate 1121 of the second shell 112 has an annular protrusion 1121b, and the annular protrusion 1121b of the plate 1121 is matched with the annular groove 1117b of the annular wall 1111 .

In this embodiment, by matching the annular protrusion 1121b of the plate 1121 with the annular groove 1117b of the annular wall 1111, the torque generated on the plate 1121 during the rotation of the bicycle rear hub 1b can be resisted to avoid The plate body 1121 is rotated relative to the annular wall body 1111 to be released from the annular wall body 1111 .

According to the bicycle rear hub disclosed in the above-mentioned embodiments, the valve member is movably arranged in the gas passage, and its outer diameter is larger than the inner diameter of the communication hole connecting the gas passage and the accommodation space, so that when the bicycle rear hub is stationary, The valve part is blocked by gravity to block the communication hole, so that the accommodating space is not connected to the gas channel, and when the rear hub of the bicycle rotates, the valve part is separated from the communication hole through the centrifugal force acting on the valve part, so that the accommodating space can pass through the gas The channel is connected to the outside. Thereby, it can be ensured that when the rear wheel hub of the bicycle is stationary, water will not enter the accommodating space and damage the motor assembly in the accommodating space, and When the motor assembly operates to rotate the rear wheel hub of the bicycle, external air can enter the accommodating space to dissipate heat from the motor assembly.

Although the present invention is disclosed above with the aforementioned preferred embodiments, it is not intended to limit the present invention. Any person familiar with the similar art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of patent protection for inventions shall be defined in the scope of patent application attached to this specification.

11: Main body

1111: ring wall

1112: side wall

1116: Connecting hole

113:Accommodating space

12: Flange

121: first surface

122: second surface

123: end face

1251: first channel

12511: first paragraph

12512: second paragraph

12513: the third paragraph

12514: opening

1252:Second channel

20: Valve

40: plug body

41: Board

42: Insertion Department

D1: outer diameter

D2, D3, D4: inner diameter

Claims (10)

A rear wheel hub of a bicycle, comprising: a shell, including a main body and a flange, the flange protrudes from the main body along the radial direction of the main body, and the main body has a communicating accommodating space and at least one communication hole, the flange part has at least one gas channel connected to the outside, and the at least one gas channel is connected to the accommodating space through the at least one communication hole; and at least one valve member is movably arranged on the In at least one gas channel, the outer diameter of the at least one valve element is greater than the inner diameter of the at least one communication hole; wherein, when the rear hub of the bicycle is stationary, the at least one valve element is blocked by gravity to block the at least one communication hole. hole, so that the accommodating space does not communicate with the at least one gas channel; when the rear hub of the bicycle rotates, the centrifugal force acting on the at least one valve part makes the at least one valve part separate from the at least one communication hole, so that the accommodating The storage space communicates with the outside through the at least one gas channel. The bicycle rear hub as claimed in claim 1, wherein the flange portion has a first surface and a second surface, the first surface and the second surface are opposite to each other in the axial direction of the main body portion, and the at least one gas The passage has a first passage and a second passage, one end of the first passage is connected to the at least one communication hole, one end of the second passage is connected to the first passage, and the other end of the second passage is connected to the first passage. On a surface, the first channel and the second channel respectively extend along two different directions, and the at least one valve element is movably located in the first channel. The bicycle rear hub as claimed in claim 2, wherein the inner diameter of the second channel is smaller than the outer diameter of the at least one valve element. The bicycle rear hub as described in claim 3, wherein the first channel has a first section, a second section and a third section, and the second section is located between the first section and the third section and communicates The first section and the third section, the end of the first section away from the second section is connected to the at least one communication hole, and the second channel is connected to the second section; when the rear wheel hub of the bicycle is stationary, the at least one Different parts of the valve element are respectively located in the first section of the first channel and the at least one communication hole; when the bicycle rear hub rotates, the at least one valve element is located in the third section of the first channel. The bicycle rear hub as described in claim 3 further includes a plug body, the flange portion has an end surface in the radial direction of the main body portion, the end surface connects the first surface and the second surface, and the first channel is away from One end of the at least one communication hole has an opening, the opening is located on the end surface, the plug body includes a plate portion and at least one insertion portion, the at least one insertion portion is inserted into the first channel from the opening, and the plate part against the end face. The bicycle rear hub as described in claim 5, wherein the at least one communication hole of the main body, the at least one air channel of the flange, the at least one valve element and the at least one insertion portion of the plug The number is multiple, the first passages of the gas passages are respectively connected to the accommodating space through the communication holes, the valve parts are respectively movably arranged in the first passages of the gas passages, The inserting parts are respectively inserted into the first passages through the openings. The bicycle rear hub according to claim 2, wherein the first channel extends along the radial direction of the main body portion, and the second channel extends along the axial direction of the main body portion. The bicycle rear hub as described in Claim 2, wherein the at least one gas channel has a third channel, one end of the third channel communicates with the first channel, and extends along a direction different from that of the first channel. The direction extends to the second surface, and the inner diameter of the third channel is smaller than the outer diameter of the at least one valve element. The bicycle rear hub according to claim 8, wherein the first channel extends along the radial direction of the main body portion, and the second channel and the third channel extend along the axial direction of the main body portion. The bicycle rear hub as described in Claim 1, wherein the main body part comprises a first shell part and a second shell part assembled together, the first shell part comprises an annular wall and a side wall, and the flange part protrudes from the annular wall in the radial direction of the main body, the accommodating space and the at least one communication hole are located in the annular wall, and the side wall is connected to one end of the annular wall in the axial direction of the annular wall , the annular wall has an end surface and an annular groove, the end surface is located at the other end of the annular wall relative to the side wall, the annular groove is formed by being recessed from the end surface, and the second shell part includes a connected The plate body and an assembly column, the plate body has an annular protrusion, the assembly column is installed in the annular wall, and the annular protrusion of the plate body is matched with the annular groove of the annular wall body.

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