CN209990871U

CN209990871U - Gear wheel

Info

Publication number: CN209990871U
Application number: CN201920130126.9U
Authority: CN
Inventors: 陶长青; 刘斐; 杨鹏
Original assignee: Shanghai Chuangdu Composite Material Co Ltd
Current assignee: Shanghai Chuangdu Composite Material Co Ltd
Priority date: 2019-01-25
Filing date: 2019-01-25
Publication date: 2020-01-24
Anticipated expiration: 2029-01-25

Abstract

The embodiment of the utility model discloses a gear, a middle shaft, a connecting piece and an outer part, wherein the middle shaft comprises a first section; the connecting piece comprises a hollow first round convex body and a hollow second round convex body, the inner side surface of the second round convex body is wrapped on the outer peripheral surface of the first round convex body, and the outer peripheral surface of the first section is abutted against the inner side surface of the first round convex body; the second round convex body is provided with an annular groove, the outer part comprises a third round convex body and an annular clamping block matched with the annular groove in a clamping mode, the outer peripheral surface of the annular clamping block is connected with the inner side surface of the third round convex body, and the outer peripheral surface of the third round convex body is in a sawtooth shape. Through the joint cooperation of first annular fixture block and annular groove, increased the area of contact of connecting piece with the outer part, and then strengthened the bulk strength of gear, improved the quality of product.

Description

Gear wheel

Technical Field

The embodiment of the utility model provides a mechanical transmission part field among electric power steering system and the intelligent braking system, specificly relates to a gear.

Background

Gear refers to a mechanical element with teeth on the rim which continuously mesh to transmit motion and power. Generally, the gear comprises: the outer part is a wheel rim with a sawtooth-shaped outer peripheral surface; an intermediate shaft coaxially disposed at the center of the outer member; and the connecting piece is positioned between the outer part and the intermediate shaft and used for connecting the outer part and the intermediate shaft, and the connecting piece is wrapped on the outer peripheral surface of the intermediate shaft and is abutted against the inner side surface of the outer part.

At present, the connection between the outer part and the connecting piece of most gears is realized by the abutting of the inner side surface of the outer part and the outer peripheral surface of the connecting piece, the manner that the two smooth surfaces abut against each other causes the connection between the outer part and the connecting piece to be unstable, and the outer part and the connecting piece are easy to be separated from contact.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a gear and gear manufacturing method for among electric power assisted steering system and the intelligent braking system for the unstable problem is connected with the connecting piece to the outer part of solving the gear.

In order to solve the technical problem, the embodiment of the utility model provides a following technical scheme:

a gear, comprising:

an intermediate shaft comprising a first section;

a connector comprising a first rounded convex body and a second rounded convex body; the first round convex body is hollow, the inner side face of the second round convex body is wrapped on the outer peripheral face of the first round convex body, and the outer peripheral face of the first section of the intermediate shaft is abutted against the inner side face of the first round convex body; the second round convex body is provided with an annular groove;

the outer part comprises an annular clamping block and a third circular convex body, the annular clamping block is in clamping fit with the annular groove, the outer peripheral surface of the annular clamping block is fixedly connected with the inner side surface of the third circular convex body, and the outer peripheral surface of the third circular convex body is in a sawtooth shape.

Furthermore, the outer peripheral surface of the first section of the intermediate shaft is connected with the inner side surface of the first round convex body through a plurality of first tooth profiles and a plurality of first tooth grooves matched with the corresponding first tooth profiles in a clamping mode, so that the contact area of the intermediate shaft and the connecting piece is increased.

Furthermore, the annular groove and the annular clamping block are connected through a plurality of convex strips and a plurality of strip grooves in clamping fit with the corresponding convex strips, so that the contact area between the connecting piece and the outer part is increased.

Furthermore, annular flanges are arranged on two end faces of the second round convex body, and the distance from any point on the inner side face of each annular flange to the outer peripheral face of the first round convex body along the radial direction of the two end faces of the second round convex body is equal;

the two end faces of the second round convex body are fixedly provided with a plurality of reinforcing ribs, the reinforcing ribs are uniformly distributed along the circumferential direction of the outer peripheral face of the first round convex body, and the reinforcing ribs are respectively connected with the outer peripheral face of the first round convex body and the inner side face of the annular flange.

Further, the annular groove is formed by the outer circumferential surface of the second round convex body sinking towards the radial direction of the second round convex body, and the annular groove divides the second round convex body into a first connecting part and a second connecting part;

the first connecting part and the second connecting part are respectively provided with a plurality of first through grooves, the first through grooves respectively penetrate through two end faces of the first connecting part and two end faces of the second connecting part, and the first through grooves on the first connecting part and the first through grooves on the second connecting part are respectively and uniformly distributed along the circumferential direction of the outer peripheral surface of the first round convex body; the two end faces of the annular clamping block are provided with a plurality of first protruding columns which are matched with the corresponding first through grooves in a clamping mode.

Furthermore, a plurality of second through grooves are formed in the first connecting portion and the second connecting portion, the second through grooves penetrate through two end faces of the first connecting portion and two end faces of the second connecting portion respectively, and the second through grooves in the first connecting portion and the second through grooves in the second connecting portion are uniformly distributed in the circumferential direction of the outer peripheral surface of the first circular convex body respectively; the two end surfaces of the annular clamping block are respectively provided with a plurality of second convex columns which are in clamping fit with the corresponding second through grooves;

the shortest distance between the second through groove and the inner side face of the annular flange is smaller than the shortest distance between any one of the first through grooves and the inner side face of the annular flange.

Furthermore, a plurality of third through grooves are formed in the first connecting part and the second connecting part, the third through grooves are communicated with the corresponding second through grooves, and the cross section areas of the third through grooves are larger than those of the second through grooves; and the end surfaces of the second convex columns are fixedly connected with a plurality of third convex columns which are matched with the corresponding third through grooves in a clamping manner.

Furthermore, a plurality of fourth through grooves are formed in the first connecting portion and the second connecting portion, the plurality of fourth through grooves penetrate through two end faces of the first connecting portion and two end faces of the second connecting portion respectively, and the plurality of fourth through grooves in the first connecting portion and the plurality of fourth through grooves in the second connecting portion are uniformly distributed in the circumferential direction of the outer peripheral surface of the first round convex body respectively; and a plurality of fourth convex columns which are matched with the corresponding fourth through grooves in a clamping manner are arranged on two end faces of the annular clamping block, and the plurality of fourth convex columns are hollow.

Furthermore, the outer peripheral surface of the second round convex body is connected with the inner side surface of the third round convex body through a plurality of second tooth forms and a plurality of second tooth grooves which are in clamping fit with the corresponding second tooth forms, so that the contact area of the connecting piece and the outer part is increased.

In order to achieve the above object, an embodiment of the present invention further provides a gear manufacturing method, including:

manufacturing an intermediate shaft, wherein the intermediate shaft comprises a first section and a second section which is coaxial with the first section;

placing the intermediate shaft in a connecting piece mold, and injection-molding a connecting piece, wherein the connecting piece mold is provided with a first through hole matched with a first section of the intermediate shaft and a first positioning blind hole matched with a second section of the intermediate shaft, and the first through hole is communicated with the first positioning blind hole; the first section is arranged in the first through hole, and the second section is arranged in the first positioning blind hole; the connecting piece mold is provided with a plurality of first thin water gaps, injection molding is carried out on the connecting piece mold through the first thin water gaps so as to form the connecting piece, and the connecting piece is coated on the outer peripheral surface of the first section of the intermediate shaft to form an aggregate of the connecting piece and the intermediate shaft;

placing the aggregate in an outer part mold, and injection molding an outer part, wherein the outer periphery of the injection molded outer part is in a sawtooth shape; the outer part mold is provided with a second through hole matched with the connecting piece and a second positioning blind hole matched with the second section of the intermediate shaft, and the second through hole is communicated with the second blind hole; the connecting piece in the aggregate and the first section of the intermediate shaft are arranged in the second through hole, and the second section of the intermediate shaft is arranged in the second positioning blind hole; and the outer part mould is provided with a plurality of second thin water gaps, and the outer part mould is subjected to injection molding through the second thin water gaps so as to form the outer part and wrap the outer peripheral surface of the connecting piece.

The embodiment of the utility model provides a beneficial effect who reaches is: in the connection of the outer part and the connecting piece, the inner side surface of the outer part is abutted against the outer peripheral surface of the connecting piece, and the annular clamping block is clamped and matched with the annular groove, so that the contact area between the outer part and the connecting piece is increased, the holding force between the connecting piece and the outer part is increased, the gear can bear larger torsion, the connecting piece and the outer part are not easy to separate from the contact, and the product quality is improved.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the invention and not to limit the invention.

In the drawings:

fig. 1 is a schematic view of the overall structure of a gear according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of an intermediate shaft according to an embodiment of the present invention;

FIG. 3 is a schematic view of a connecting member according to an embodiment of the present invention;

fig. 4 is a schematic structural view of an outer part of an embodiment of the present invention;

fig. 5 is a schematic view of the internal structure of the gear according to the embodiment of the present invention;

fig. 6 is a flowchart illustrating steps of a method of manufacturing a gear according to an embodiment of the present invention.

Reference numerals: 10. an intermediate shaft; 100. a first stage; 101. a first tooth form; 110. a second stage; 20. a connecting member; 200. a first dome; 201. a first tooth slot; 210. a second dome; 211. an annular groove; 212. an annular flange; 213. reinforcing ribs; 214. a first gate; 215. a first through groove; 216. a second through groove; 217. a third through groove; 218. a fourth through groove; 219. a second tooth form; 220. a first connection portion; 230. a second connecting portion; 30. an outer member; 300. an annular fixture block; 301. a strip groove; 302. a first convex column; 303. a second convex column; 304. a third convex column; 305. a fourth convex column; 310. a third dome; 311. a second tooth slot; 312. and a third tooth form.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are presented herein only to illustrate and explain the present invention, and not to limit the present invention.

As shown in fig. 1 to 5, the gear provided by the embodiment of the present invention includes an intermediate shaft 10, a connecting member 20, and an outer member 30; the intermediate shaft 10 comprises a first section 100 and a second section 110 which is coaxial with the first section 100, and the intermediate shaft 10 is a metal piece; the connecting piece 20 comprises a first round convex body 200 and a second round convex body 210, the inner side surface of the second round convex body 210 is wrapped on the outer peripheral surface of the first round convex body 200, and the first round convex body 200 is hollow; the outer member 30 includes an annular block 300 and a third dome 310, an inner side surface of the third dome 310 is wrapped on an outer circumferential surface of the annular block 300, and a plurality of third teeth 312 are uniformly distributed on the outer circumferential surface of the third dome 310 along a circumferential direction thereof.

Referring to fig. 2 and 3, a plurality of first tooth forms 101 are uniformly distributed on the outer circumferential surface of the first section 100 of the intermediate shaft 10 along the circumferential direction thereof, and a plurality of first tooth grooves 201 which are in clamping fit with the corresponding first tooth forms 101 are uniformly distributed on the inner side surface of the first round convex body 200 along the circumferential direction thereof; the first tooth profile 101 is matched with the corresponding first tooth groove 201 in a clamping manner, so that the contact area between the intermediate shaft 10 and the connecting piece 20 is increased, and further the holding force between the intermediate shaft 10 and the connecting piece 20 is increased, so that the gear can bear larger torsion, and the intermediate shaft 10 and the connecting piece 20 are not easy to separate from contact.

Referring to fig. 3 and 4, the second dome 210 is provided with an annular groove 211 engaged with the annular latch 300 to increase the contact area between the connecting member 20 and the outer member 30. The annular groove 211 is formed by recessing the outer circumferential surface of the second dome 210 toward the radial direction of the second dome 210, and the annular groove 211 divides the second dome 210 into a first connection part 220 and a second connection part 230.

The groove bottom of the annular groove 211 is provided with a plurality of convex strips, and the inner side surface of the annular fixture block 300 is provided with a plurality of strip grooves 301 which are in clamping fit with the corresponding convex strips so as to increase the contact area between the connecting piece 20 and the outer piece 30.

The end face of the first connecting portion 220, which is far away from the annular groove 211, is a first end face, the end face of the second connecting portion 230, which is far away from the annular groove 211, is a second end face, the first end face and the second end face are both provided with the annular flange 212, the distance from any point on the inner side face of the annular flange 212 on the first end face to the outer peripheral face of the first circular convex body 200 along the radial direction of any end face of the second circular convex body 210 is equal, and the distance from any point on the inner side face of the annular flange 212 on the second end face to the outer peripheral face of the first circular convex body 200 along the radial direction of any end face of the second circular convex body.

The first end surface and the second end surface are both fixedly provided with a plurality of reinforcing ribs 213, and the plurality of reinforcing ribs 213 are uniformly distributed along the circumferential direction of the outer circumferential surface of the first round convex body 200. Both ends of the first end-face reinforcing rib 213 are connected to the outer peripheral surface of the first dome 200 and the inner side surface of the first end-face annular flange 212, respectively, and both ends of the second end-face reinforcing rib 213 are connected to the outer peripheral surface of the first dome 200 and the inner side surface of the second end-face annular flange 212, respectively.

The arrangement of the reinforcing ribs 213 increases the overall strength of the gear.

The part of the reinforcing ribs 213 is provided with a first inlet 214 of the connector 20.

A plurality of first through grooves 215 are respectively arranged on the first connecting part 220 and the second connecting part 230, the plurality of first through grooves 215 on the first connecting part 220 all penetrate through two end faces of the first connecting part 220, the plurality of first through grooves 215 on the second connecting part 230 all penetrate through two end faces of the second connecting part 230, and the plurality of first through grooves 215 on the first connecting part 220 and the plurality of first through grooves 215 on the second connecting part 230 are respectively and uniformly distributed along the circumferential direction of the outer circumferential surface of the first round convex body 200; the two end faces of the annular fixture block 300 are respectively provided with a plurality of first protruding columns 302 which are in clamping fit with the corresponding first through grooves 215.

The first connecting portion 220 and the second connecting portion 230 are both provided with a plurality of second through grooves 216, the plurality of second through grooves 216 on the first connecting portion 220 all penetrate through two end faces of the first connecting portion 220, the plurality of second through grooves 216 on the second connecting portion 230 all penetrate through two end faces of the second connecting portion 230, and the plurality of second through grooves 216 on the first connecting portion 220 and the plurality of second through grooves 216 on the second connecting portion 230 are respectively and uniformly distributed along the circumferential direction of the outer circumferential surface of the first round convex body 200; the two end faces of the annular fixture block 300 are provided with a plurality of second convex columns 303 which are in clamping fit with the corresponding second through grooves 216.

The shortest distance of the second through groove 216 from the inner side surface of the annular flange 212 is smaller than the shortest distance of any of the first through grooves 215 from the inner side surface of the annular flange 212.

Referring to fig. 3, 4 and 5, a plurality of third through grooves 217 are disposed on the first connecting portion 220 and the second connecting portion 230, the third through grooves 217 are communicated with the corresponding second through grooves 216, and the cross-sectional area of the third through grooves 217 is larger than that of the second through grooves 216; the end surfaces of the second convex columns 303 are fixedly connected with third convex columns 304 which are matched with the corresponding third through grooves 217 in a clamping mode.

The third through groove 217 and the third boss 304 snap-fitted with the corresponding third through groove 217 are arranged, so that the notch of the second through groove 216 is not easy to expand, and the connection between the connecting piece 20 and the outer part 30 is tighter.

The first convex column 302 is in clamping fit with the corresponding first through groove 215, the second convex column 303 is in clamping fit with the corresponding second through groove 216, and the third convex column 304 is in clamping fit with the corresponding third through groove 217, so that the contact area between the connecting piece 20 and the outer part 30 is increased, the holding force between the connecting piece 20 and the outer part 30 is increased, the gear can bear larger torsion, and the connecting piece 20 and the outer part 30 are not easy to separate from contact.

The first connecting portion 220 and the second connecting portion 230 are both provided with a plurality of fourth through grooves 218, the plurality of fourth through grooves 218 on the first connecting portion 220 all penetrate through two end faces of the first connecting portion 220, the plurality of fourth through grooves 218 on the second connecting portion 230 all penetrate through two end faces of the second connecting portion 230, and the plurality of fourth through grooves 218 on the first connecting portion 220 and the plurality of fourth through grooves 218 on the second connecting portion 230 are respectively and uniformly distributed along the circumferential direction of the outer circumferential surface of the first round convex body 200; the two end surfaces of the annular fixture block 300 are respectively provided with a plurality of fourth protruding columns 305 engaged with the corresponding fourth through grooves 218, and the plurality of fourth protruding columns 305 are hollow.

The hollow fourth boss 305 is a second ingate for the outer part 30.

A plurality of second tooth shapes 219 are respectively and uniformly distributed on the first connecting part 220 along the outer peripheral surface of the first connecting part 220 and on the second connecting part 230 along the outer peripheral surface of the second connecting part 230, and a plurality of second tooth grooves 311 in clamping fit with the corresponding second tooth shapes 219 are arranged on the inner side surface of the third round convex body 310; the contact area of the connection member 20 and the outer member 30 is increased, and thus the clasping force between the connection member 20 and the outer member 30 is increased.

Referring to fig. 6, a method for manufacturing a gear according to an embodiment of the present invention is further provided, and the method for manufacturing a gear according to the above embodiment is exemplarily described as follows:

step S100, the intermediate shaft 10 is manufactured.

Specifically, the intermediate shaft 10 includes a first section 100 and a second section 110; the cross-sectional area of the first section 100 is larger than that of the second section 110, and a plurality of first tooth forms 101 are uniformly distributed on the outer circumferential surface of the first section 100 along the circumferential direction. The second section 110 includes a first optical face.

Step S120, the intermediate shaft 10 is placed in a connector mold, and the connector 20 is injection molded.

Specifically, a first through hole matched with the first section 100 of the intermediate shaft 10 and a first positioning blind hole matched with the second section 110 of the intermediate shaft 10 are arranged on the connecting piece die, the first through hole is communicated with the first positioning blind hole, and the aperture of the first through hole is larger than that of the first positioning blind hole; the first section 100 is arranged in the first through hole, the second section 110 is arranged in the first positioning blind hole, and a first smooth surface of the second section 110 is abutted against the inner side surface of the first positioning blind hole; a plurality of first thin water gaps are formed in the connecting piece mold, injection molding is conducted on the connecting piece mold through the first thin water gaps in a tunnel glue feeding mode so that the connecting piece 20 can be molded, the connecting piece 20 is coated on the outer peripheral face of the first section 100 of the intermediate shaft 10, and an aggregate of the connecting piece 20 and the intermediate shaft 10 is formed. The first thin water ports on the connecting piece mold correspond to the first inlet gates 214 on the connecting piece 20 after injection molding.

The arrangement of the first positioning blind hole can ensure the concentricity of the intermediate shaft 10 and the injection molded connecting piece 20.

In step S120, the connecting member 20 is formed to have a plurality of first tooth grooves 201 formed on the outer circumferential surface of the connecting member 20 along the circumferential direction thereof, so as to be in snap-fit with the corresponding first tooth profiles 101 on the intermediate shaft 10, thereby increasing the holding force between the intermediate shaft 10 and the connecting member 20, so that the gear can bear a larger torque force, and the intermediate shaft 10 and the connecting member 20 are not easily separated from each other.

Step S130, placing the aggregate in an outer part mold, and injection molding the outer part 30, wherein a plurality of third tooth profiles 312 are uniformly distributed on the outer peripheral surface of the outer part 30 after injection molding along the circumferential direction; the outer part mould is provided with a second through hole matched with the connecting piece 20 and a second positioning blind hole matched with the second section 110 of the intermediate shaft 10, the second through hole is communicated with the second positioning blind hole, and the aperture of the second through hole is larger than that of the second positioning blind hole; the connecting piece 20 and the first section 100 of the intermediate shaft 10 are arranged in the second through hole, and the outer peripheral surface of the connecting piece 20 is abutted against the inner side surface of the second through hole; the second section 110 of the intermediate shaft 10 is arranged in the second positioning blind hole, and the first smooth surface is abutted against the inner side surface of the second positioning blind hole; the outer part mold is provided with a plurality of second thin water ports, and the outer part mold is injected with plastic through the second thin water ports so that the outer part 30 is molded and coated on the outer peripheral surface of the connecting piece 20. And a plurality of second thin water ports on the outer part mold respectively correspond to the fourth convex columns 305 arranged in the hollow of the outer part 30 after injection molding.

The provision of the second positioning blind hole ensures concentricity of the assembly with the injection molded outer member 30.

The injection molded connector 20 includes a first dome 200, a second dome 210, and a circular groove 211 formed on the second dome 210, wherein the inner side of the second dome 210 is wrapped on the outer circumferential surface of the first dome 200. The injection molded connector 20 includes an annular fixture block 300 and a third dome 310, which are engaged with the annular groove 211, and the inner side of the third dome 310 is wrapped on the outer circumferential surface of the annular fixture block 300.

A plurality of convex strips are formed at the groove bottom of the annular groove 211 of the connecting piece 20, and a plurality of strip grooves 301 which are in clamping fit with the corresponding convex strips are formed at the inner side surface of the annular fixture block 300 of the outer piece 30, so that the contact area between the connecting piece 20 and the outer piece 30 is increased, and the holding force between the connecting piece 20 and the outer piece 30 is increased.

A plurality of ribs 213 are formed on both end surfaces of the second round protrusions 210 of the coupling 20 to increase the overall strength of the gear.

A plurality of first through grooves 215, second through grooves 216 and third through grooves 217 are formed on the connecting piece 20, wherein the second through grooves 216 are communicated with the third through grooves 217, and the cross section area of the third through grooves 217 is the cross section area of the second through grooves 216; a plurality of first convex columns 302 in clamping fit with the corresponding first through grooves 215, a plurality of second convex columns 303 in clamping fit with the corresponding second through grooves 216, and a plurality of third convex columns 304 in clamping fit with the corresponding third through grooves 217 are formed on two end faces of the annular fixture block 300 of the outer part 30, and the third convex columns 304 are formed on the end faces of the corresponding second convex columns 303, so that the contact area between the connecting piece 20 and the outer part 30 is increased, and the holding force between the connecting piece 20 and the outer part 30 is further increased.

A plurality of fourth grooves 218 are formed in the coupling member 20, a plurality of fourth studs 305 are formed on both end surfaces of the annular locking block 300 of the outer member 30 to be snap-fitted into the corresponding fourth grooves 218, and the fourth studs 305 are hollow.

A plurality of second tooth shapes 219 uniformly distributed along the circumferential direction are formed on the outer circumferential surface of the connecting piece 20, and a plurality of second tooth grooves 311 in snap fit with the corresponding second tooth shapes 219 are formed on the inner side surface of the third convex body 310 of the outer piece 30, so that the contact area between the connecting piece 20 and the outer piece 30 is increased, and the holding force between the connecting piece 20 and the outer piece 30 is increased.

The embodiment of the utility model provides a beneficial effect who reaches is:

(1) compared with the prior art in which the gear of the sprue inlet part needs to be removed by machining in the final injection molding process of the outer part 30, the gear manufacturing method of the embodiment of the invention reduces the machining procedures, improves the production efficiency and reduces the production cost;

(2) compared with the gear manufacturing method in which the outer part 30 is processed firstly in the prior art, the gear manufacturing method provided by the embodiment of the invention reduces the influence of the post-processing process on the outer part 30 by putting the outer part 30 with the highest functional requirement in the gear in the last procedure for processing, thereby effectively improving the qualification rate of finished products;

(3) the connecting piece 20 is made of plastic, so that the heat conduction between the injection-molded outer part 30 and the metal piece intermediate shaft 10 can be well blocked, and the influence on the quality of a product caused by the dimensional change of the outer part 30 due to uneven cooling of the plastic in the injection molding process can be prevented.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing embodiments, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A gear, comprising:

an intermediate shaft comprising a first section;

2. The gear according to claim 1, wherein the outer peripheral surface of the first section of the intermediate shaft is connected to the inner side surface of the first round convex body through a plurality of first tooth profiles and a plurality of first tooth grooves which are in snap fit with the corresponding first tooth profiles, so as to increase the contact area between the intermediate shaft and the connecting piece.

3. The gear according to claim 1, wherein the annular groove and the annular locking block are connected by a plurality of convex strips and a plurality of strip grooves which are in snap fit with the corresponding convex strips so as to increase the contact area between the connecting piece and the outer member.

4. The gear according to claim 1, wherein the two end faces of the second circular convex body are provided with annular flanges, and the distance from any point on the inner side face of each annular flange to the outer peripheral face of the first circular convex body along the radial direction of the two end faces of the second circular convex body is equal;

5. The gear according to claim 4, wherein the annular groove is formed by an outer peripheral surface of the second dome being recessed toward a radial direction of the second dome, the annular groove dividing the second dome into a first connecting portion and a second connecting portion;

6. The gear according to claim 5, wherein a plurality of second through grooves are formed in each of the first connecting portion and the second connecting portion, the plurality of second through grooves respectively penetrate through two end faces of the first connecting portion and two end faces of the second connecting portion, and the plurality of second through grooves in the first connecting portion and the plurality of second through grooves in the second connecting portion are uniformly distributed along the circumferential direction of the outer circumferential surface of the first round convex body; the two end surfaces of the annular clamping block are respectively provided with a plurality of second convex columns which are in clamping fit with the corresponding second through grooves;

7. The gear according to claim 6, wherein a plurality of third through grooves are arranged on the first connecting part and the second connecting part, the third through grooves are communicated with the corresponding second through grooves, and the cross section area of each third through groove is larger than that of each second through groove; and the end surfaces of the second convex columns are fixedly connected with a plurality of third convex columns which are matched with the corresponding third through grooves in a clamping manner.

8. The gear according to claim 5, wherein a plurality of fourth through grooves are formed in each of the first connecting portion and the second connecting portion, the plurality of fourth through grooves respectively penetrate through two end faces of the first connecting portion and two end faces of the second connecting portion, and the plurality of fourth through grooves in the first connecting portion and the plurality of fourth through grooves in the second connecting portion are uniformly distributed in the circumferential direction of the outer circumferential surface of the first round convex body; and a plurality of fourth convex columns which are matched with the corresponding fourth through grooves in a clamping manner are arranged on two end faces of the annular clamping block, and the plurality of fourth convex columns are hollow.

9. The gear according to claim 1, wherein the outer peripheral surface of the second torus and the inner side surface of the third torus are connected through a plurality of second tooth forms and a plurality of second tooth grooves which are in snap fit with the corresponding second tooth forms, so as to increase the contact area between the connecting piece and the outer member.