Center shaft sleeving structure of bicycle

Abstract

The invention discloses a bicycle middle shaft sleeving structure, belongs to the field of bicycle parts, solves the problem that an existing middle shaft sleeve cannot be stably and conveniently lubricated, and comprises a middle end connecting rod, protection parts, an inserting groove and a bearing assembly. A bearing assembly is fixedly installed in the protection part, an inserting groove is formed in the protection part, the inserting groove penetrates through the interior of the protection part, a lubricating mechanism is arranged in the protection part, the lubricating mechanism comprises a lubricating injection groove, a circulating groove and a sealing plug block, and the circulating groove is formed in the protection part. By arranging the lubricating mechanism and the bearing assembly, lubricating oil in the bearing assembly can be stably and conveniently supplemented, and the situation that balls in the bearing assembly cannot be stably lubricated after the middle shaft sleeve is used for a long time is prevented, so that the using stability of equipment is guaranteed, and the overall service life of the equipment is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of bicycle parts, and in particular relates to a bicycle middle shaft set structure. Background Art

[0002] Bicycle accessories are a general term for all parts and accessories of a bicycle. According to the large structural framework of the bicycle, it can be divided into several categories: frame, tire, pedal components, front fork assembly, chain, flywheel, etc. Among the 25 accessories of a bicycle, such as frame, tire, pedal, brake, chain, etc., the basic parts are indispensable. Among them, the frame is the skeleton of the bicycle, which bears the greatest weight of people and goods. According to the working characteristics of each accessory, it can be roughly divided into the guide system, drive system, and brake system. Among them, the middle shaft sleeve is the main component that assists the bicycle pedal to rotate and act.

[0003] Chinese patent CN219295617U discloses a bicycle middle shaft set structure, including a shaft bowl, a mounting groove, a bearing, a shaft stopper, a dust cover, a through hole, a locking plate, a key washer, a washer body and a flange; the two shaft bowls are fixedly connected with bearings, the bearings are fixedly connected with shaft stops, one side of one shaft bowl is provided with a key washer, one side of the key washer is provided with a washer body, and one side of the other shaft bowl is provided with a dust cover; the two shaft bowls are provided with mounting grooves, and the bearings are fixedly connected in the mounting grooves; the shaft stopper is provided with a flange; the dust cover is provided with a locking plate on one side, and a threaded hole is opened on the outer wall of one side of the locking plate; The above design can effectively reduce the overall weight of the middle shaft sleeve through the use and coordination of multiple groups of components, and can subsequently effectively prevent external dust from entering the interior of the equipment, thereby extending the service life of the equipment itself. However, there are certain problems in actual use. Specifically, when in use, the equipment mainly relies on the bearing inside the middle shaft sleeve for transmission. Once it is used for too long, the bearing lacks lubrication and the practical effect of the middle shaft sleeve itself will be affected. The above design cannot stably add lubricating oil, which affects the maintenance of the equipment itself. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In order to solve the problems raised in the above background technology, the present invention adopts the following technical solutions.

[0006] A bicycle middle axle set structure includes a middle-end connecting rod, a protective member, a plug-in slot and a bearing assembly, wherein the protective member is symmetrically and slidably mounted on the outside of the middle-end connecting rod, and the bearing assembly is fixedly mounted inside the protective member, the protective member is provided with a plug-in slot, and the plug-in slot runs through the inside of the protective member, and the protective member is provided with a lubrication mechanism, the lubrication mechanism includes a lubrication injection groove, a circulation groove and a sealing block, the protective member is provided with a circulation groove, the protective member is provided with a sealing block, the sealing block is connected to the circulation groove, the sealing block is threadedly mounted on the side of the lubrication injection groove, and the protective mechanism is fixedly mounted on the side of the protective member.

[0007] As a preferred technical solution of the present invention, the sealing block includes a rotating plate and a threaded rod, the threaded rod is threadedly installed on the side of the lubrication injection groove, the rotating plate is fixedly installed on the side of the threaded rod, and a cross groove is opened on the side surface of the rotating plate.

[0008] As a preferred technical solution of the present invention, the lubrication mechanism further comprises a sealing gasket, which is sleeved on the outside of the sealing block and is slidably connected to the side opening of the lubrication injection groove.

[0009] As a preferred technical solution of the present invention, the bearing assembly includes an inner ring, a retaining groove, an outer ring and metal balls. The inner ring is arranged on the side of the middle-end connecting rod, and a retaining groove is opened inside the inner ring. The retaining groove is slidably connected to the middle-end connecting rod. An outer ring is arranged inside the protective part, and metal balls are equidistantly arranged between the outer ring and the inner ring.

[0010] As a preferred technical solution of the present invention, the bearing assembly also includes a collecting groove, and the collecting grooves are equidistantly arranged inside the outer ring, and the collecting grooves penetrate the inner wall of the outer ring, and the overall radius of the collecting grooves is smaller than the radius of the metal ball itself.

[0011] As a preferred technical solution of the present invention, the protective mechanism includes a dust cover, a fitting groove, a matching card slot and an extrusion assembly. A fitting groove is opened on the side of the protective member, and the dust cover is slidably installed inside the fitting groove. Matching card slots are symmetrically opened on the side of the fitting groove, and the extrusion assembly is symmetrically arranged inside the protective member.

[0012] As a preferred technical solution of the present invention, the extrusion assembly includes an extrusion movable groove, an extrusion side plate and an extrusion screw. The protective member is provided with an extrusion movable groove, the extrusion side plate is slidably installed in the extrusion movable groove, the extrusion screw is rotatably installed on the side of the extrusion side plate, and the extrusion screw is threadedly connected to the protective member.

[0013] As a preferred technical solution of the present invention, the extrusion assembly further includes an extrusion rotary block and a receiving groove. The extrusion rotary block is fixedly mounted on the end of the extrusion screw, and a receiving groove is provided on the side surface of the protective member.

[0014] As a preferred technical solution of the present invention, the protective member includes an outer protective sleeve, a side baffle and an installation threaded end. The outer protective sleeve is arranged outside the middle end connecting rod, the side baffle is fixedly installed on the side of the outer protective sleeve, and the installation threaded end is fixedly installed on the outer surface of the outer protective sleeve.

[0015] As a preferred technical solution of the present invention, the protective member further includes a push groove, and the side surfaces of the side baffle are provided with push grooves at equal intervals.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present invention, by providing a lubrication mechanism and a bearing assembly, the lubricating oil inside the bearing assembly can be stably and conveniently replenished, thereby preventing the situation in which the balls inside the bearing assembly cannot be stably lubricated after the middle sleeve has been used for too long, thereby ensuring the stability of the equipment during use and extending the service life of the entire equipment; (2) In the present invention, by providing a protective mechanism and a protective member, the areas on both sides of the central shaft sleeve can be shielded and protected to prevent external liquids and impurities from entering the interior of the equipment and causing corrosion to the internal parts of the equipment, thereby improving the stability of the equipment itself during use. In addition, the installation operation of the protective cover is simple and convenient, which greatly saves the time of equipment assembly and improves the overall work efficiency of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a three-dimensional diagram of the overall structure of the present invention; Figure 2 It is a three-dimensional diagram of the structure after the components of the present invention are disassembled; Figure 3 A three-dimensional diagram of the lubrication mechanism structure of the present invention; Figure 4 It is a structural schematic diagram of the bearing assembly in the present invention; Figure 5 It is a structural schematic diagram of the protection mechanism in the present invention; Figure 6 It is a schematic diagram of the structure of the extrusion assembly in the present invention; Figure 7 It is a schematic diagram of the structure of the protective element in the present invention.

[0018] The corresponding relationship between the illustrations and component names in the figure is as follows: 1. Middle end connecting rod; 2. Protective part; 21. Outer protective sleeve; 22. Side baffle; 23. Mounting threaded end; 24. Pushing groove; 3. Plug-in groove; 4. Bearing assembly; 41. Inner sleeve ring; 42. Positioning groove; 43. Outer sleeve ring; 44. Metal ball; 45. Collecting groove; 5. Lubricating mechanism; 51. Lubricating injection groove; 52. Circulation groove; 53. Sealing block; 54. Sealing gasket; 6. Protective mechanism; 61. Dust cover; 62. Fitting connecting groove; 63. Matching slot; 64. Extrusion assembly; 641. Extrusion moving groove; 642. Extrusion side plate; 643. Extrusion screw; 644. Extrusion rotating block; 645. Storage groove. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments. The present invention provides the following embodiments.

[0022] Depend on Figure 1 , Figure 2 and Figure 3 As shown, a bicycle middle shaft set structure includes a middle-end connecting rod 1, a protective member 2, a plug-in groove 3 and a bearing assembly 4, the middle-end connecting rod 1 is symmetrically and slidably installed on the outside, the protective member 2 is fixedly installed with the bearing assembly 4, the protective member 2 is provided with a plug-in groove 3, and the plug-in groove 3 runs through the protective member 2, the protective member 2 is provided with a lubrication mechanism 5, the lubrication mechanism 5 includes a lubrication injection groove 51, a circulation groove 52 and a sealing block 53, the protective member 2 is provided with a circulation groove 52, the protective member 2 is provided with a sealing block 53, the sealing block 53 is connected with the circulation groove 52, the sealing block 53 is threadedly installed on the side of the lubrication injection groove 51, and the protective member 2 is fixedly installed with a protective mechanism 6 on the side.

[0023] During use, the device is placed at the target position, and then the bearing assembly 4 is installed inside the protective member 2, and the two ends of the middle connecting rod 1 pass through the bearing assembly 4 and the protective member 2 at the same time through the matching of the plug-in slot 3, completing the preliminary combination of the middle shaft sleeve, and then the side of the plug-in slot 3 is sealed by using the protective mechanism 6 to prevent external impurities from passing through the plug-in slot 3 into the protective member 2 and causing pollution to the bearing assembly 4 inside the protective member 2, and the protective member 2 is used to install the device to the target position of the bicycle to complete the installation of the device. When the bearing assembly 4 inside the protective member 2 needs to be fixed, the protective member 2 is installed. When lubricating the component 4, the lubrication mechanism 5 is used to timely and stably lubricate the internal components of the bearing assembly 4, and the sealing block 53 is rotated to turn the sealing block 53 out from the side opening of the lubrication injection groove 51 to expose the lubrication injection groove 51 as a whole, and then the lubricating oil to be used is injected into the lubrication injection groove 51. Through the cooperation of the lubrication injection groove 51 and the circulation groove 52, the lubricating oil enters the protective component 2 to lubricate the bearing assembly 4 inside the protective component 2, thereby simplifying the overall maintenance operation of the equipment and extending the service life of the equipment itself.

[0024] By the attached Figure 3 As shown, in this embodiment, the sealing block 53 includes a rotating plate and a threaded rod. The threaded rod is threadedly installed on the side of the lubricating injection groove 51, the rotating plate is fixedly installed on the side of the threaded rod, and a cross groove is opened on the side surface of the rotating plate.

[0025] During use, the threaded rod is used to close or open the side opening of the lubrication injection groove 51, which is convenient for the input of lubricating oil and the sealing of the entire space of the lubrication injection groove 51, thereby ensuring the stability of the internal components of the protective member 2 during use. Moreover, by installing the rotating plate, the threaded rod can be rotated more simply and labor-savingly, thereby simplifying the overall operation of the equipment.

[0026] By the attached Figure 3 As shown, in this embodiment, the lubrication mechanism 5 further includes a sealing gasket 54 , which is sleeved on the outside of the sealing block 53 , and the sealing gasket 54 is slidably connected to the side opening of the lubrication injection groove 51 .

[0027] During use, the sealing gasket 54 is set to be sleeved on the outside of the sealing block 53, and then continuously rotated into the lubrication injection groove 51 through the sealing block 53, and the sealing gasket 54 also enters the lubrication injection groove 51. When the sealing block 53 is rotated to the target position, the sealing gasket 54 can fit tightly between the sealing block 53 and the lubrication injection groove 51, further strengthening the overall sealing of the lubrication mechanism 5 and preventing external impurities from entering the interior of the equipment.

[0028] By the attached Figure 4As shown, in this embodiment, the bearing assembly 4 includes an inner ring 41, a retaining groove 42, an outer ring 43 and metal balls 44. The inner ring 41 is arranged on the side of the middle connecting rod 1, and a retaining groove 42 is opened inside the inner ring 41. The retaining groove 42 is slidably connected to the middle connecting rod 1. An outer ring 43 is arranged inside the protective member 2, and metal balls 44 are equidistantly arranged between the outer ring 43 and the inner ring 41.

[0029] During use, the output end of the middle connecting rod 1 is inserted into the inner ring 41 through the use of the locking groove 42 to complete the connection between the bearing assembly 4 and the middle connecting rod 1. When the middle connecting rod 1 rotates, the middle connecting rod 1 drives the inner ring 41 to rotate synchronously under the limitation and cooperation of the locking groove 42. The multiple groups of metal balls 44 filled between the inner ring 41 and the outer ring 43 are used to enhance the lubrication of the inner ring 41 itself and assist the stable rotation of the inner ring 41, thereby ensuring the stability of the bearing assembly 4 during overall use.

[0030] By the attached Figure 4 As shown, in this embodiment, the bearing assembly 4 also includes a collecting groove 45. The outer ring 43 has collecting grooves 45 equidistantly provided inside, and the collecting grooves 45 penetrate the inner wall of the outer ring 43. The overall radius of the collecting groove 45 is smaller than the radius of the metal ball 44 itself.

[0031] During use, by opening the collecting groove 45, when the bearing assembly 4 rotates following the middle connecting rod 1, the metal ball 44 between the inner ring 41 and the outer ring 43 plays a certain role in lubrication and auxiliary rotation. With the passage of time and the increase in the number of rotations of the bearing assembly 4 and the middle connecting rod 1, the lubricating oil inside the bearing assembly 4 will gradually decrease. The use of the collecting groove 45 can receive and guide the lubricating oil injected by the lubrication mechanism 5, allowing the lubricating oil to enter between the inner ring 41 and the outer ring 43, and lubricate the outer surface of the metal ball 44, thereby extending the service life of the equipment itself.

[0032] By the attached Figure 5 As shown, in this embodiment, the protective mechanism 6 includes a dust cover 61, a fitting groove 62, a matching slot 63 and an extrusion assembly 64. The side of the protective member 2 is provided with a fitting groove 62, and the dust cover 61 is slidably installed inside the fitting groove 62. The side of the fitting groove 62 is symmetrically provided with matching slots 63, and the extrusion assembly 64 is symmetrically arranged inside the protective member 2.

[0033] During use, when the middle connecting rod 1 passes through the protective part 2 and the bearing assembly 4 through the plug-in slot 3, the gap between the middle connecting rod 1 and the inner wall of the protective part 2 and the bearing assembly 4 is too large, and external dust, liquid and other impurities can enter the interior of the device through the gap, affecting the normal use of the internal components of the device. At this time, the dust cover 61 can be pressed into the fitting groove 62. At this time, the matching slot 63 on the side of the dust cover 61 will automatically align with the internal components of the extrusion assembly 64. Then, through the use of the extrusion assembly 64, the position of the dust cover 61 is locked. At this time, the dust cover 61 can block the gap between the middle connecting rod 1 and the protective part 2 and the bearing assembly 4, and play a certain dust-proof and shielding role, preventing external dust, liquid and other impurities from entering the interior of the device.

[0034] By the attached Figure 6 As shown, in this embodiment, the extrusion assembly 64 includes an extrusion movable groove 641, an extrusion side plate 642 and an extrusion screw 643. The protective member 2 is provided with an extrusion movable groove 641, the extrusion side plate 642 is slidably installed in the extrusion movable groove 641, the extrusion screw 643 is rotatably installed on the side of the extrusion side plate 642, and the extrusion screw 643 is threadedly connected to the protective member 2.

[0035] During use, before the dust cover 61 is installed, it is necessary to rotate the extrusion screw 643. Under the rotation of the extrusion screw 643, the extrusion screw 643 will continuously move outward using its own thread, driving the extrusion side plate 642 to slide to the side away from the matching slot 63. When the dust cover 61 is positioned, the extrusion screw 643 is rotated again. With the cooperation of the extrusion screw 643, the extrusion side plate 642 passes through the opening on the side of the extrusion moving slot 641 and enters the inside of the matching slot 63, thereby fixing the position of the dust cover 61 and ensuring the stability of the dust cover 61 during use.

[0036] By the attached Figure 5 As shown, in this embodiment, the extrusion assembly 64 also includes an extrusion rotating block 644 and a receiving groove 645. The extrusion rotating block 644 is fixedly installed at the end of the extrusion screw 643, and the side surface of the protective member 2 is provided with a receiving groove 645.

[0037] During use, by using the extrusion turn block 644, when the extrusion screw 643 is rotated, the staff can press the hex wrench directly into the internal notch of the extrusion turn block 644 to quickly rotate the extrusion screw 643 as a whole. The opening of the storage groove 645 ensures that after the extrusion side plate 642 moves to the target position, the extrusion turn block 644 can fit with the side surface of the protective member 2, and the extrusion turn block 644 will not protrude alone, which facilitates the installation and use of the protective member 2.

[0038] By the attached Figure 7As shown, in this embodiment, the protective member 2 includes an outer protective sleeve 21, a side baffle plate 22 and a mounting threaded end 23. The outer protective sleeve 21 is arranged outside the middle end connecting rod 1, the side baffle plate 22 is fixedly installed on the side of the outer protective sleeve 21, and the mounting threaded end 23 is fixedly installed on the outer surface of the outer protective sleeve 21.

[0039] During use, the outer protective sleeve 21 is installed at the target position of the bicycle, and then the side baffle 22 is rotated so that the installation thread end 23 on the outer surface of the outer protective sleeve 21 continuously enters the interior of the bicycle bearing seat, thereby achieving rapid installation and reinforcement of the protective member 2 and simplifying the installation steps of the device itself.

[0040] By the attached Figure 7 As shown, in this embodiment, the protective member 2 further includes a push groove 24 , and the side surfaces of the side baffle plate 22 are provided with push grooves 24 at equal intervals.

[0041] During use, by opening the push groove 24, it can save effort when rotating the side baffle 22. The end of the wrench is inserted into the push groove 24, and the push groove 24 is used to form a support point. Subsequently, only the wrench needs to be rotated to complete the installation and positioning of the entire protective part 2, which simplifies the overall operation steps of the equipment.

[0042] Working principle: When the present invention is used, the device is placed at the target position, and then the bearing assembly 4 is installed inside the protective part 2, and the two ends of the middle-end connecting rod 1 pass through the bearing assembly 4 and the protective part 2 at the same time through the cooperation of the plug-in slot 3 to complete the preliminary combination of the middle shaft sleeve, and then the side of the plug-in slot 3 is closed by using the protective mechanism 6 to prevent external impurities from passing through the plug-in slot 3 into the protective part 2 and causing pollution to the bearing assembly 4 inside the protective part 2. When the middle-end connecting rod 1 passes through the protective part 2 and the bearing assembly 4 through the plug-in slot 3, the gap between the middle-end connecting rod 1 and the inner wall of the protective part 2 and the bearing assembly 4 is too large, and external dust, liquid and other impurities can enter the interior of the device through the gap, affecting the normal use of the internal components of the device. At this time, the dust cover 61 can be pressed into the fitting connection slot 62. At this time, the matching slot 63 on the side of the dust cover 61 will automatically align with the internal components of the extrusion assembly 64, and then through the use of the extrusion assembly 64, The position of the dust cover 61 is locked. At this time, the dust cover 61 can cover the gap between the middle connecting rod 1 and the protective part 2 and the bearing assembly 4, and play a certain dustproof and shielding role, preventing external dust, liquid and other impurities from entering the interior of the equipment. By using the protective part 2, the equipment is installed at the target position of the bicycle to complete the installation of the equipment. When it is necessary to lubricate the bearing assembly 4 inside the protective part 2, the lubrication mechanism 5 is used to timely and stably lubricate the internal components of the bearing assembly 4, and the sealing block 53 is rotated to rotate the sealing block 53 out of the side opening of the lubrication injection groove 51 to expose the lubrication injection groove 51 as a whole. Then, the lubricating oil to be used is injected into the lubrication injection groove 51. Through the cooperation of the lubrication injection groove 51 and the circulation groove 52, the lubricating oil enters the protective part 2 to lubricate the bearing assembly 4 inside the protective part 2, thereby simplifying the overall maintenance operation of the equipment and extending the service life of the equipment itself. The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope determined by the claims submitted for the present invention.

Claims

1. A bicycle middle shaft set structure, comprising a middle end connecting rod (1), a protective member (2), a plug-in slot (3) and a bearing assembly (4), wherein the protective member (2) is symmetrically and slidably mounted on the outside of the middle end connecting rod (1), the bearing assembly (4) is fixedly mounted inside the protective member (2), the plug-in slot (3) is formed inside the protective member (2), and the plug-in slot (3) passes through the inside of the protective member (2), and the characteristics are: The protective member (2) is provided with a lubricating mechanism (5) inside, the lubricating mechanism (5) comprising a lubricating injection groove (51), a circulation groove (52) and a sealing block (53), the protective member (2) is provided with a circulation groove (52), the protective member (2) is provided with a sealing block (53), the sealing block (53) is connected to the circulation groove (52), the sealing block (53) is threadedly mounted on the side of the lubricating injection groove (51), and the protective member (2) is fixedly mounted with a protective mechanism (6) on the side.

2. The bicycle middle shaft set structure according to claim 1, characterized in that: The sealing block (53) comprises a rotating plate and a threaded rod, wherein the threaded rod is threadedly mounted on the side of the lubricating injection groove (51), the rotating plate is fixedly mounted on the side of the threaded rod, and a cross groove is formed on the side surface of the rotating plate.

3. The bicycle middle shaft set structure according to claim 2, characterized in that: The lubrication mechanism (5) further comprises a sealing gasket (54), wherein the sealing gasket (54) is sleeved on the outside of the sealing block (53), and the sealing gasket (54) is slidably connected to a side opening of the lubrication injection groove (51).

4. The bicycle middle shaft set structure according to claim 1, characterized in that: The bearing assembly (4) comprises an inner sleeve ring (41), a retaining groove (42), an outer sleeve ring (43) and metal balls (44); the inner sleeve ring (41) is arranged on the side of the middle connecting rod (1); a retaining groove (42) is provided inside the inner sleeve ring (41); the retaining groove (42) is slidably connected to the middle connecting rod (1); an outer sleeve ring (43) is provided inside the protective member (2); and metal balls (44) are equidistantly provided between the outer sleeve ring (43) and the inner sleeve ring (41).

5. The bicycle middle shaft set structure according to claim 4, characterized in that: The bearing assembly (4) further comprises a collecting groove (45), wherein the outer ring (43) has collecting grooves (45) equidistantly formed therein, the collecting grooves (45) penetrate the inner wall of the outer ring (43), and the overall radius of the collecting grooves (45) is smaller than the radius of the metal ball (44) itself.

6. The bicycle middle shaft set structure according to claim 1, characterized in that: The protective mechanism (6) comprises a dust cover plate (61), a fitting groove (62), a matching slot (63) and an extrusion assembly (64); the protective member (2) is provided with a fitting groove (62) on the side thereof; the dust cover plate (61) is slidably mounted inside the fitting groove (62); matching slots (63) are symmetrically provided on the side thereof; and the extrusion assembly (64) is symmetrically arranged inside the protective member (2).

7. The bicycle middle shaft set structure according to claim 6, characterized in that: The extrusion assembly (64) comprises an extrusion movable groove (641), an extrusion side plate (642) and an extrusion screw (643); the protective member (2) is provided with an extrusion movable groove (641); the extrusion side plate (642) is slidably mounted inside the extrusion movable groove (641); the extrusion screw (643) is rotatably mounted on the side of the extrusion side plate (642); and the extrusion screw (643) is threadedly connected to the protective member (2).

8. The bicycle middle shaft set structure according to claim 7, characterized in that: The extrusion assembly (64) further comprises an extrusion rotating block (644) and a receiving groove (645); the extrusion rotating block (644) is fixedly mounted on the end of the extrusion screw (643); and the receiving groove (645) is provided on the side surface of the protective member (2).

9. The bicycle middle shaft set structure according to claim 1, characterized in that: The protective member (2) comprises an outer protective sleeve (21), a side baffle (22) and a mounting threaded end (23); the outer protective sleeve (21) is arranged outside the middle connecting rod (1); the side baffle (22) is fixedly mounted on the side of the outer protective sleeve (21); and the mounting threaded end (23) is fixedly mounted on the outer surface of the outer protective sleeve (21).

10. The bicycle middle shaft set structure according to claim 9, characterized in that: The protective member (2) further comprises a push groove (24), and the side surfaces of the side baffle plate (22) are provided with push grooves (24) at equal intervals.

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