A bicycle crank anti-falling device

Abstract

The utility model relates to a bicycle crank technical field discloses a bicycle crank anti -drop device, including main crank and axle, the oblique toothed groove is established in the main crank rear side top, the main crank front side top is provided with the snap ring, the main crank inside is provided with the locating rod, the axle front end outer wall is provided with the oblique toothed sleeve, the axle front end is provided with the positioning hole, the axle front end inside is provided with the screw hole, the screw hole inside screw thread connection has the bolt, the main crank bottom fixedly connected has the convex block. In the utility model, when the device is assembled, the oblique toothed sleeve and the oblique toothed groove are engaged to prevent the relative rotation of the main crank and the axle, the locating rod is inserted into the positioning hole to limit the radial displacement, the bolt cooperates with the snap ring to prevent shaking, multiple fixation improves the reliability, according to the height of the rider, the spring reset is fixed initially through the alignment of the clamping block and the clamping groove, the screw fastening double restraint adjusts the main crank and the length of the adjusting crank, and the applicability is enhanced.

Description

Technical Field

[0001] This utility model relates to the field of bicycle crank technology, and in particular to a bicycle crank anti-fall-off device. Background Technology

[0002] In the field of cycling equipment, bicycles, as a means of transportation that combines commuting, fitness, and outdoor sports, directly impact cycling safety, efficiency, and user experience due to the stability and adaptability of their core transmission components. As cyclists increasingly demand personalization, the transmission system is required to not only possess long-term reliable connection performance to prevent safety hazards such as component detachment, but also to allow for flexible adjustment of transmission component lengths based on user scenarios and heights, cycling habits, and other factors. This adaptability caters to diverse cycling needs. Therefore, the structural design of key transmission components such as cranks has become a key area of ​​optimization within the industry.

[0003] Currently, there are significant shortcomings in the connection and adjustment structures between the crank and bottom bracket of bicycles on the market. Regarding connection reliability, existing crank-bottom bracket assembly mostly relies on a single bolt or simple slot positioning, lacking multiple constraint mechanisms. On the one hand, a single fixing method cannot simultaneously restrict relative rotation and radial displacement. During long-term riding, the main crank and bottom bracket are prone to relative loosening due to vibration, even posing a safety risk of the main crank detaching. On the other hand, the contact area of ​​traditional connection structures is small, concentrating radial force on a few connection points, leading to accelerated component wear and shortening the overall lifespan of the main crank. Regarding length adaptability, existing cranks are mostly one-piece designs, making it difficult to efficiently meet the precise adaptation needs of users of different heights. To address these technical problems, this application proposes a bicycle crank anti-detachment device. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a bicycle crank anti-dislodgement device. During assembly, the helical tooth sleeve engages with the helical tooth groove to prevent relative rotation between the main crank and the bottom bracket. A positioning rod inserted into a positioning hole limits radial displacement. Bolts and retaining rings prevent wobbling. Multiple fixing mechanisms enhance reliability. The helical teeth increase the contact area, and the positioning rod distributes radial force, reducing wear. The device can be adjusted according to the rider's height by aligning the locking blocks and slots, using a spring for initial fixation, and tightening screws for double constraints to adjust the length of the main crank and the adjustable crank, meeting various fitting requirements.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A bicycle crank anti-fall-off device includes a main crank and a bottom bracket. The main crank has a helical toothed groove on the top rear side and a retaining ring on the top front side. A positioning rod is provided inside the main crank. A helical toothed sleeve is provided on the outer wall of the front end of the bottom bracket. A positioning hole is provided at the front end of the bottom bracket. A threaded hole is provided inside the front end of the bottom bracket, and a bolt is threaded into the threaded hole. A convex block is fixedly connected to the bottom end of the main crank. Pressing blocks are provided on both the left and right sides of the top of the convex block. A connecting plate is fixedly connected to the outer wall of the pressing block. The connecting plate is connected to the adjusting crank through a locking assembly.

[0006] Furthermore, the locking assembly includes a slot formed inside the adjusting crank, a locking block is provided inside the slot, the outer wall of the locking block is provided on the outer wall of the connecting plate, a spring is provided on the inner wall of the connecting plate, and the locking block has a wedge-shaped design.

[0007] Furthermore, the outer wall of the helical tooth sleeve is disposed inside the helical tooth groove, and the positioning rod is disposed inside the positioning hole.

[0008] Furthermore, the outer surface of the retaining ring is polygonal, and the inner surface of the retaining ring is threaded, with the outer wall of the bolt threaded into the inner surface of the retaining ring.

[0009] Furthermore, the main crank has sliding grooves on both sides, a protective cover is provided on the outer wall of the main crank, sliders are fixedly connected inside the left and right sides of the protective cover, the outer walls of the sliders are slidably connected to the sliding grooves, and screws are provided between the main crank and the protective cover.

[0010] Furthermore, a positioning groove is provided at the top of the adjusting crank, and the outer wall of the top end of the convex block is disposed inside the positioning groove.

[0011] Furthermore, a guide rod is provided between two adjacent connecting plates, and a screw is provided between the convex block and the adjusting crank.

[0012] This utility model has the following beneficial effects: 1. In this utility model, during device assembly, the helical tooth sleeve engages with the helical tooth groove to achieve initial positioning, preventing the main crank and the central shaft from rotating relative to each other; the positioning rod is inserted into the positioning hole to limit radial displacement; the bolt connection, combined with the retaining ring, prevents wobbling, forming multiple fixation mechanisms. This significantly improves connection reliability and prevents the main crank from falling off; the helical teeth increase the contact area, and the positioning rod shares the radial force, reducing wear and extending service life.

[0013] 2. In this utility model, the device can flexibly adapt the extension length of the main crank and the adjusting crank according to the rider's height. Initial adjustment is achieved by sliding the convex block along the positioning groove. Combined with the precise alignment of the locking block and the slot, and the spring return, initial fixation is quickly completed, and then tightened with screws to form a double constraint. This not only efficiently meets the length adaptation needs in different scenarios but also effectively prevents offset or slippage after adjustment, ensuring riding safety and stability, and improving the flexibility and reliability of the device. Attached Figure Description

[0014] Figure 1 This is a perspective view of a bicycle crank anti-fall-off device proposed in this utility model; Figure 2 This is a schematic diagram of the main crank structure of a bicycle crank anti-fall-off device proposed in this utility model; Figure 3 This is a schematic diagram of the protective cover structure of a bicycle crank anti-fall-off device proposed in this utility model; Figure 4 This is a cross-sectional view of the convex block of a bicycle crank anti-fall-off device proposed in this utility model.

[0015] Legend: 1. Main crank; 2. Adjusting crank; 3. Bottom shaft; 4. Helical tooth groove; 5. Positioning rod; 6. Snap ring; 7. Bolt; 8. Helical tooth sleeve; 9. Positioning hole; 10. Threaded hole; 11. Protective cover; 12. Slide groove; 13. Slider; 14. Convex block; 15. Positioning groove; 16. Pressing block; 17. Connecting plate; 18. Spring; 19. Locking block; 20. Locking groove; 21. Guide rod. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Reference Figures 1-3This utility model provides an embodiment of a bicycle crank anti-fall-off device, including a main crank 1 and a bottom bracket 3. The main crank 1 has a helical tooth groove 4 on the top rear side and a retaining ring 6 on the top front side. The main crank 1 has a positioning rod 5 inside. The bottom bracket 3 has a helical tooth sleeve 8 on the outer wall of its front end and a positioning hole 9 at its front end. The bottom bracket 3 has a threaded hole 10 inside its front end and a bolt 7 is threaded inside the threaded hole 10. The outer wall of the helical tooth sleeve 8 is located inside the helical tooth groove 4. The positioning rod 5 is located inside the positioning hole 9. The retaining ring 6 has a polygonal design on its exterior and a thread inside. The bolt 7 is threaded inside the retaining ring 6.

[0018] Specifically, during the assembly stage, the helical tooth sleeve 8 on the outer wall of the front end of the central shaft 3 is first embedded into the helical tooth groove 4 on the top rear side of the main crank 1. The tooth profile of the helical tooth sleeve 8 and the helical tooth groove 4 are perfectly matched, and preliminary positioning can be achieved through tooth surface meshing, effectively preventing relative rotation between the main crank 1 and the central shaft 3 during operation. At this time, the positioning rod 5 inside the main crank 1 is also inserted into the positioning hole 9 opened at the front end of the central shaft 3. The positioning rod 5 and the positioning hole 9 adopt a transition fit to further limit the radial displacement of the main crank 1 and the central shaft 3. Finally, the bolt 7 is inserted from the front side of the main crank 1 and sequentially threaded into the threaded hole 10 inside the retaining ring 6 and the front end of the central shaft 3. The retaining ring 6 adopts a polygonal design on the outside. During assembly, the polygonal surface contact prevents the main crank 1 from wobbling left and right, ensuring that the bolt 7 can be tightened stably. The bolt 7 tightly fits the main crank 1, retaining ring 6 and central shaft 3 together, forming a multi-fixed structure. During the operation of the device, when riding... When the rider pedals the main crank 1, the main crank 1 transmits power to the bottom bracket 3 through the engagement of the helical tooth groove 4 and the helical tooth sleeve 8. At this time, the positioning rod 5 can help bear part of the radial force, avoiding excessive wear of the helical tooth structure due to force concentration. At the same time, the bolt 7 locks the retaining ring 6, and the retaining ring 6 further restricts the left and right movement of the main crank 1 by fitting against the front side of the main crank 1, ensuring smooth and stable movement. Through the multiple fixing structures of helical tooth engagement, positioning rod 5 positioning and bolt 7 locking, the connection reliability between the main crank 1 and the bottom bracket 3 is greatly improved, effectively preventing the safety hazard of the main crank 1 falling off during riding. The design of the helical tooth structure can increase the contact area and reduce the force. Combined with the radial force distribution by the positioning rod 5, it reduces component wear and extends the overall service life of the device. After the helical tooth groove 4 and the helical tooth sleeve 8 are engaged, there will be a side clearance to avoid jamming due to thermal expansion. The polygonal design of the retaining ring 6 makes it easy to fix during assembly and reduces the installation difficulty.

[0019] Reference Figure 1 , Figure 3 and Figure 4The main crank 1 has a convex block 14 fixedly connected to its bottom end. Pressing blocks 16 are provided on both the left and right sides of the top of the convex block 14. A connecting plate 17 is fixedly connected to the outer wall of the pressing block 16. A slot 20 is provided inside the adjusting crank 2. A locking block 19 is provided inside the slot 20. The outer wall of the locking block 19 is set on the outer wall of the connecting plate 17. A spring 18 is provided on the inner wall of the connecting plate 17. The locking block 19 has a wedge-shaped design. Slide grooves 12 are provided on both the left and right sides of the main crank 1. A protective cover 11 is provided on the outer wall of the main crank 1. A slider 13 is fixedly connected to the left and right sides of the protective cover 11. The outer wall of the slider 13 is slidably connected to the slide groove 12. A screw is provided between the main crank 1 and the protective cover 11. A positioning groove 15 is provided at the top of the adjusting crank 2. The top outer wall of the convex block 14 is set inside the positioning groove 15. A guide rod 21 is provided between two adjacent connecting plates 17. A screw is provided between the convex block 14 and the adjusting crank 2.

[0020] Specifically, when adjusting the length of the device, the appropriate telescopic length of the main crank 1 and the adjusting crank 2 is determined according to the rider's height, riding habits, and other needs. The convex block 14 at the bottom of the main crank 1 slides up and down along the positioning groove 15 at the top of the adjusting crank 2. Since multiple locking blocks 19 are fixedly connected from top to bottom on both sides of the connecting plate 17, and multiple corresponding locking slots 20 are opened inside the adjusting crank 2, during the sliding process, pressing the pressing block 16 with one hand causes the connecting plate 17 to retract towards the inside of the convex block 14, which continuously squeezes the wedge-shaped inclined surface of the locking block 19, and the spring 18 is compressed simultaneously. When sliding to the target length position, a certain set of locking blocks 19 will be precisely aligned with the corresponding locking slot 20 inside the adjusting crank 2. At this time, the spring 18 is released from compression, pushing the connecting plate 17 to move the locking block 19. The locking block 19 is embedded in the slot 20 to form a preliminary length positioning; then, the screws between the convex block 14 and the adjusting crank 2 are tightened to form a stable connection, and the screw installation positions are symmetrically distributed on both sides of the central axis of the adjusting crank 2. Combined with the overall balanced weight design of the device, it can avoid the phenomenon of uneven weight distribution on the left and right sides when tightening, thus completing the telescopic adjustment and connection. It not only meets the length adaptation requirements in different scenarios, but also avoids the problem of offset or sliding after adjustment through the dual constraints of the positioning of the locking block 19 and the slot 20 combined with the screw fixing. When the protective cover 11 slides along the slide groove 12 through the slider 13, it can always cover the connection part between the convex block 14 and the adjusting crank 2, protecting the internal structure. The outer wall of the slide groove 12 is equipped with a dustproof strip to prevent external mud and sand from entering the interior of the slide groove 12.

[0021] Working principle: During the assembly stage, the helical tooth sleeve 8 on the outer wall of the front end of the bottom bracket 3 is first embedded into the helical tooth groove 4 on the top rear side of the main crank 1. The complete meshing of the tooth surfaces achieves initial positioning, preventing the main crank 1 and the bottom bracket 3 from rotating relative to each other. At the same time, the positioning rod 5 inside the main crank 1 is inserted into the positioning hole 9 at the front end of the bottom bracket 3 to restrict the lateral displacement of the two through transition fit. Then, the bolt 7 is inserted from the front side of the main crank 1 and connected to the internally threaded and externally polygonal retaining ring 6 and the threaded hole 10 at the front end of the bottom bracket 3 in sequence. The polygonal retaining ring 6 prevents the main crank 1 from wobbling left and right through surface contact, ensuring that the bolt 7 is tightened stably. Finally, a multi-fixing structure is formed by helical tooth meshing, positioning rod 5 positioning, and bolt 7 locking. This not only improves the reliability of the connection between the main crank 1 and the bottom bracket 3 and prevents the main crank 1 from falling off during riding, but also increases the contact area through the helical teeth and shares the radial force with the positioning rod 5, reducing component wear. During length adjustment, based on the rider's height and habits, press the pressing block 16 on the top of the convex block 14 at the bottom of the main crank 1, causing the connecting plate 17 to retract inward, squeezing the wedge-shaped locking block 19 and compressing the spring 18. Then, slide the convex block 14 along the positioning groove 15 at the top of the adjusting crank 2 to the target length. At this time, the locking block 19 at the corresponding position aligns with the locking groove 20 inside the adjusting crank 2. The spring 18 resets and pushes the locking block 19 into the locking groove 20 to complete the initial positioning. Then, the screws between the convex block 14 and the adjusting crank 2 are tightened to achieve length adaptation and stable connection, preventing displacement after adjustment. At the same time, the protective cover 11 on the outer wall of the main crank 1 is slidably installed in the sliding groove 12 through the sliders 13 on both sides and fixed with screws, which can protect the internal structure. The guide rod 21 between adjacent connecting plates 17 ensures the movement stability of the connecting plate 17 when it retracts and resets, so that the device takes into account the safety of preventing drop, the flexibility of length adjustment, and applicability.

[0022] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A bicycle crank anti-dislodgement device, comprising a main crank (1) and a bottom bracket (3), characterized in that: The main crank (1) has a helical tooth groove (4) on the top rear side, a retaining ring (6) on the top front side of the main crank (1), a positioning rod (5) inside the main crank (1), a helical tooth sleeve (8) on the outer wall of the front end of the central shaft (3), a positioning hole (9) on the front end of the central shaft (3), a threaded hole (10) inside the front end of the central shaft (3), a bolt (7) threaded inside the threaded hole (10), a convex block (14) fixedly connected to the bottom end of the main crank (1), pressing blocks (16) on both the left and right sides of the top of the convex block (14), a connecting plate (17) fixedly connected to the outer wall of the pressing block (16), and the connecting plate (17) connected to the adjusting crank (2) through a locking assembly.

2. The bicycle crank anti-dislodgement device according to claim 1, characterized in that: The locking assembly includes a slot (20) opened inside the adjusting crank (2), a locking block (19) is provided inside the slot (20), the outer wall of the locking block (19) is provided on the outer wall of the connecting plate (17), the inner wall of the connecting plate (17) is provided with a spring (18), and the locking block (19) is wedge-shaped.

3. The bicycle crank anti-dislodgement device according to claim 1, characterized in that: The outer wall of the helical tooth sleeve (8) is set inside the helical tooth groove (4), and the positioning rod (5) is set inside the positioning hole (9).

4. The bicycle crank anti-dislodgement device according to claim 1, characterized in that: The outer side of the retaining ring (6) is polygonal, and the inner side of the retaining ring (6) is threaded. The outer wall of the bolt (7) is threaded and connected to the inside of the retaining ring (6).

5. A bicycle crank anti-dislodgement device according to claim 1, characterized in that: The main crank (1) has grooves (12) on both the left and right sides. The outer wall of the main crank (1) is provided with a protective cover (11). The protective cover (11) is fixedly connected to the inner side of the left and right sides of the protective cover (11). The outer wall of the slider (13) is slidably connected to the groove (12). Screws are provided between the main crank (1) and the protective cover (11).

6. A bicycle crank anti-dislodgement device according to claim 1, characterized in that: The top of the adjusting crank (2) is provided with a positioning groove (15), and the top outer wall of the convex block (14) is set inside the positioning groove (15).

7. A bicycle crank anti-dislodgement device according to claim 1, characterized in that: A guide rod (21) is provided between two adjacent connecting plates (17), and a screw is provided between the convex block (14) and the adjusting crank (2).

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