A bicycle frame structure

Abstract

The utility model discloses a bicycle frame structure, bicycle frame structure includes front triangle and rear fork structure, and the rear fork structure includes rear upper fork, rear middle fork, rear lower fork and rear fork connecting piece, the rear upper fork rear end is connected rear fork connecting piece, and the front end of rear upper fork is connected the upper portion of front triangle, the rear middle fork rear end is connected rear fork connecting piece, and the front end of rear middle fork is connected the middle part of front triangle, the rear lower fork rear end is connected rear fork connecting piece, and the front end of rear lower fork is connected the middle part of front triangle, when the frame bears the additional weight of electric component, and the rear middle fork bears the vertical load of considerable part, and the overall load disperses to more rear fork, and effectively alleviates the burden of rear upper fork and rear lower fork. This structure is especially suitable for the electric bicycle of heavy load demand, can improve the service life and security of frame significantly.

Description

Technical Field

[0001] This utility model relates to the field of bicycle technology, and more particularly to a bicycle frame structure. Background Technology

[0002] The bicycle frame is a crucial supporting structure for a bicycle. Its strength, toughness, elasticity, and durability determine the bicycle's lifespan and riding experience. Common welding methods include electric arc welding, argon arc welding, and gas shielded welding.

[0003] A bicycle frame consists of components such as the seat tube, top tube, down tube, head tube, rear stays, chainstays, and bottom bracket tube. Frames are typically categorized as road bike frames or mountain bike frames, and even within road and mountain bike frames, there are further subdivisions. The angles between the seat tube, top tube, down tube, head tube, rear stays, chainstays, and bottom bracket tube vary between different frames. The frame structure is divided into the front triangle and the rear fork. Broadly speaking, the structure between the seat tube and head tube is the front triangle. Specifically, the seat tube, top tube, down tube, head tube, and bottom bracket tube connect to form the front triangle, which is the main structure supporting the rider. The rear fork typically includes the rear stays and chainstays. The rear stays and chainstays connect with the front triangle to form another triangular structure, thereby increasing the stability of the rear stays.

[0004] With the electrification of bicycles, batteries, motors, controllers, and other structures have been added to the frame. These structures primarily bear the load of the frame, which needs to support an additional weight of 0-10 kg. Since the average adult weighs approximately 65 kg, the weight that bicycles need to bear after electrification has increased significantly, resulting in a substantial increase in the total load-bearing capacity of the frame. Traditional rear forks rely solely on a double-fork structure (rear top and bottom forks) for load-bearing, which exposes significant deficiencies under the heavy load conditions brought about by electrification, making it difficult to meet the rigid requirements of electric bicycles. This insufficient load-bearing capacity not only affects the lifespan of the frame but may also lead to safety hazards such as decreased stability and reduced handling during riding. Therefore, there is an urgent need for a bicycle frame structure that can improve the load-bearing capacity of the rear fork. Utility Model Content

[0005] In order to solve the technical problem of insufficient load-bearing capacity of the rear fork of the bicycle frame after electrification in the existing technology, one of the objectives of this utility model is to provide a bicycle frame structure.

[0006] One of the objectives of this utility model is achieved through the following technical solution: A bicycle frame structure, the bicycle frame structure including a front triangle and a rear fork structure, the rear fork structure including a rear top fork, a rear center fork, a rear bottom fork, and a rear fork connector; The rear end of the upper rear fork is connected to the rear fork connector, and the front end of the upper rear fork is connected to the upper part of the front triangle. The rear end of the rear center fork is connected to the rear fork connector, and the front end of the rear center fork is connected to the middle of the front triangle; The rear end of the lower fork is connected to the lower fork connector, and the front end of the lower fork is connected to the middle of the front triangle.

[0007] In some alternative embodiments, the first end of the rear fork connector extends upward and connects to the rear end of the upper rear fork, the second end of the rear fork connector extends forward and connects to the rear end of the middle rear fork, and the middle portion of the rear fork connector connects to the rear end of the lower rear fork.

[0008] In some optional embodiments, the second end of the rear fork connector is provided with a welding surface, the welding surface is provided with a plug-in member, the rear end face of the rear center fork is provided with a sleeve hole adapted to the plug-in member, and the rear end of the rear center fork is sleeved on the plug-in member.

[0009] In some alternative embodiments, a retaining block is further provided on the welding surface, the retaining block being located on the side wall of the connector, and the rear end face of the rear center fork abutting against the retaining block.

[0010] In some alternative embodiments, the connector is provided with a cable inlet for internal wiring, one end of which is connected to the internal cavity of the front triangle and the other end of which is connected to the internal cavity of the rear center fork.

[0011] In some alternative embodiments, a cable outlet hole is provided on the side wall of the rear center fork, and the cable outlet hole communicates with the internal cavity of the rear center fork.

[0012] In some alternative implementations, the rear center fork is tilted upwards from rear to front; The rear end of the lower fork is connected to the middle of the lower fork connector from below, and the lower fork is inclined downward from back to front.

[0013] In some optional embodiments, the number of the upper rear fork, middle rear fork, lower rear fork, and rear fork connector is two, respectively located on the left and right sides of the rear of the front triangle.

[0014] In some alternative embodiments, the rear fork further includes a bridge tube disposed between the front ends of the two rear upper forks, with each end of the bridge tube connected to the front ends of the two rear upper forks respectively.

[0015] In some alternative embodiments, one of the rear fork connectors is provided with a mounting post for mounting a brake, and the other rear fork connector is provided with a tail hook for mounting a transmission.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows: The original rear fork structure was a four-point support structure. By adding a rear center fork, a more stable force-bearing system is formed. The addition of the rear center fork allows the load to be distributed to the front triangle through six connection points. In actual use, when the frame bears the additional weight of the electric components, the rear center fork bears a significant portion of the vertical load, distributing the overall load to more of the rear forks and effectively reducing the burden on the rear top and bottom forks. This structure is particularly suitable for electric bicycles with high load-bearing requirements, significantly improving the frame's lifespan and safety. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the bicycle frame structure of this utility model; Figure 2 This is a side view of the bicycle frame structure of this utility model; Figure 3 This is a three-dimensional schematic diagram of the rear fork structure in the bicycle frame structure of this utility model; Figure 4 This is an exploded view of the rear fork structure in the bicycle frame structure of this utility model; Figure 5 This is a schematic diagram of the structure of a rear fork connector in the bicycle frame structure of this utility model.

[0018] Figure 6 This is a schematic diagram of the structure of another rear fork connector in the bicycle frame structure of this utility model.

[0019] Explanation of reference numerals in the attached diagram: 1. Anterior triangle; 2. Rear upper fork; 3. Rear center fork; 31. Cable exit hole; 4. Rear downward fork; 5. Rear fork connector; 51. Connector; 52. Retaining block; 53. Cable tray; 54. Cable inlet; 55. Mounting post; 6. Bridge pipe. Detailed Implementation

[0020] The following will refer to the appendices in the embodiments of this application. Figure 1 To be continued Figure 6 The technical solutions in the embodiments of this application are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0022] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0023] like Figure 1-3 As shown, this invention provides a basic embodiment of a bicycle frame structure. The bicycle frame structure includes a front triangle 1 and a rear fork structure, wherein the rear fork structure includes a top fork 2, a center fork 3, a chain fork 4, and a rear fork connector 5. The rear end of the top fork 2 is connected to the rear fork connector 5, and the front end is connected to the upper part of the front triangle 1; the rear end of the center fork 3 is connected to the rear fork connector 5, and the front end is connected to the middle part of the front triangle 1; the rear end of the chain fork 4 is connected to the rear fork connector 5, and the front end is connected to the middle part of the front triangle 1.

[0024] The original rear fork structure was a four-connection-point support structure. By adding the rear center fork 3, a more stable force-bearing system is formed. The addition of the rear center fork 3 allows the load to be distributed to the front triangle 1 through six connection points, making the overall force distribution of the rear fork structure more dispersed and giving it a stronger load-bearing capacity. In actual use, when the frame bears the additional weight of the electric components, the rear center fork 3 bears a significant portion of the vertical load, distributing the overall load to more of the rear forks and effectively reducing the burden on the rear top fork 2 and rear chainstay 4. This structure is particularly suitable for electric bicycles with high load-bearing requirements, significantly improving the frame's lifespan and safety.

[0025] In the specific design of the rear fork connector 5, such as Figure 4 , Figure 5 and Figure 6As shown, the first end of the rear fork connector 5 extends upward to connect with the rear end of the upper rear fork 2, the second end extends forward to connect with the rear end of the middle rear fork 3, and the middle part connects with the rear end of the lower rear fork 4. This three-dimensional extension design allows the rear fork connector 5 to effectively coordinate the force transmission of the three fork tubes. The rear fork connector 5 is manufactured using precision casting technology, and the material is high-strength aluminum alloy, ensuring strength while controlling weight. The structural shape of each connection part was optimized through finite element analysis to ensure uniform stress distribution.

[0026] To further improve connection accuracy and assembly efficiency, such as Figure 5 , Figure 6 As shown, a welding surface is provided at the second end of the rear fork connector 5, and a connector 51 is provided on the welding surface. The rear end face of the rear center fork 3 has a socket hole adapted to the connector 51. During assembly, the rear end of the rear center fork 3 is fitted onto the connector 51, forming a precise positioning. The outer diameter of the connector 51 and the inner diameter of the socket hole adopt a transition fit, and the fit tolerance is controlled within the range of 0.05-0.1mm. This design ensures precise positioning before welding and greatly reduces the frame size deviation caused by assembly errors.

[0027] like Figure 5 , Figure 6 As shown, a retaining block 52 is also provided on the welding surface. The retaining block 52 is located on the side wall of the connector 51, and the rear end face of the rear fork 3 abuts against the retaining block 52. The retaining block 52 has a height of 1.5mm and is arranged in a circumferentially evenly distributed manner, with 2 to 4 blocks. The retaining block 52 and the connector 51 are integrally machined, and the material is consistent with that of the rear fork connector 5. During the welding process, the retaining block 52 ensures that a constant welding gap is maintained between the rear fork 3 and the welding surface. This gap ensures sufficient filling of the solder and avoids welding defects caused by excessively small gaps. At the same time, the retaining block 52 also acts as a reinforcing rib, enhancing the structural strength of the root of the connector 51.

[0028] Considering the wiring requirements of electric bicycles, such as Figure 5 , Figure 6 As shown, the inner surface of the rear fork connector 5 has a wiring groove 53; the connector 51 has an inlet hole 54 for internal cable routing, one end of which connects to the wiring groove 53, and the other end connects to the internal cavity of the rear center fork 3. The inlet hole 54 has a diameter of 8mm, and its inner wall is polished to prevent the wire from being scratched when passing through. This design allows the wire coming from the front of the frame to pass through the internal cavity of the front triangle 1, the internal cavity of the rear center fork 3, the inlet hole 54, and finally the outlet hole 31 to extend to the wiring groove 53, connecting to the rear wheel motor or other electronic equipment. The entire cable routing path is completely hidden inside the frame, which is both aesthetically pleasing and safe.

[0029] Meanwhile, a cable outlet hole 31 is provided on the side wall of the rear center fork 3, which connects to the internal cavity of the rear center fork 3. In this way, the routed cables can be led out through the cable outlet hole 31, for example, the brake cable can be led out through the cable outlet hole 31, increasing the diversity of the wiring path.

[0030] Regarding the posture design of the rear fork connector 5, such as Figure 5 , Figure 6 As shown, the second end of the rear fork connector 5 is inclined upwards, and the rear center fork 3 is inclined upwards from rear to front; the rear end of the rear lower fork 4 is connected to the middle of the rear fork connector 5 from below, and the rear lower fork 4 is inclined downwards from rear to front. This unique spatial layout makes the rear center fork 3 and the rear lower fork 4 form a scissor-like support structure, which can effectively resist loads in different directions. The rear center fork 3 mainly bears the vertical load, while the rear lower fork 4 is better able to cope with the horizontal force generated during braking. The tilt angle of the two fork tubes has been optimized and calculated to provide sufficient movement space for the rear wheel while ensuring structural strength.

[0031] In the preferred embodiment, such as Figure 2 , Figure 3 As shown, there are two of each of the rear top fork 2, rear center fork 3, rear chain fork 4, and rear fork connector 5, located on the left and right sides of the rear of the front triangle 1, respectively. This symmetrical design ensures the balance and stability of the frame. The two rear fork structures are independently welded together via the rear fork connector 5, but are connected to each other via the bridge tube 6. The bridge tube 6 is located between the front ends of the two rear top forks 2, with its two ends connected to the front ends of the two rear top forks 2, respectively. The bridge tube 6 not only enhances the overall integrity of the two rear fork structures but also provides additional mounting points for the frame, which can be used to mount racks or other accessories.

[0032] In addition, to facilitate external cable routing, the bottom of the rear center fork 3 is equipped with a cable clamping groove, which can be used to fix the external cable routing.

[0033] To improve the functionality of the frame, such as Figure 5 , Figure 6 As shown, one of the rear fork connectors 5 has a mounting post 55 for mounting the brake, and the other rear fork connector 5 has a tail hook 56 for mounting the derailleur. The tail hook 56 is detachable for easy replacement in case of damage, and is made of chromium-molybdenum steel, which has been heat-treated to ensure sufficient strength and toughness.

[0034] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. A bicycle frame structure, characterized in that, The bicycle frame structure includes a front triangle and a rear fork structure, and the rear fork structure includes a rear top fork, a rear center fork, a rear bottom fork, and a rear fork connector. The rear end of the upper rear fork is connected to the rear fork connector, and the front end of the upper rear fork is connected to the upper part of the front triangle. The rear end of the rear center fork is connected to the rear fork connector, and the front end of the rear center fork is connected to the middle of the front triangle; The rear end of the lower fork is connected to the lower fork connector, and the front end of the lower fork is connected to the middle of the front triangle.

2. The bicycle frame structure as described in claim 1, characterized in that, The first end of the rear fork connector extends upward and connects to the rear end of the upper rear fork, the second end of the rear fork connector extends forward and connects to the rear end of the middle rear fork, and the middle part of the rear fork connector connects to the rear end of the lower rear fork.

3. The bicycle frame structure as described in claim 2, characterized in that, The second end of the rear fork connector is provided with a welding surface, and a plug-in component is provided on the welding surface. The rear end face of the rear center fork is provided with a sleeve hole adapted to the plug-in component, and the rear end of the rear center fork is sleeved on the plug-in component.

4. The bicycle frame structure as described in claim 3, characterized in that, A retaining block is also provided on the welding surface. The retaining block is located on the side wall of the connector, and the rear end face of the rear center fork abuts against the retaining block.

5. The bicycle frame structure as described in claim 3, characterized in that, The inner surface of the rear fork connector is provided with a wiring groove; The connector is provided with a cable inlet hole for internal wiring. One end of the cable inlet hole is connected to the wiring groove, and the other end of the cable inlet hole is connected to the internal cavity of the rear center fork.

6. The bicycle frame structure as described in claim 5, characterized in that, The rear center fork has a cable outlet hole on its side wall, which connects to the internal cavity of the rear center fork.

7. The bicycle frame structure as described in claim 2, characterized in that, The second end of the rear fork connector is inclined upward, and the rear center fork is inclined upward from back to front; The rear end of the lower fork is connected to the middle of the lower fork connector from below, and the lower fork is inclined downward from back to front.

8. The bicycle frame structure as described in claim 1, characterized in that, The number of the upper rear fork, middle rear fork, lower rear fork, and rear fork connectors are all two, and they are respectively located on the left and right sides of the rear part of the front triangle.

9. The bicycle frame structure as described in claim 8, characterized in that, The rear fork also includes a bridge tube, which is disposed between the front ends of the two rear upper forks, and the two ends of the bridge tube are respectively connected to the front ends of the two rear upper forks.

10. The bicycle frame structure as described in claim 8, characterized in that, One of the rear fork connectors is provided with a mounting post for installing a brake, and the other rear fork connector is provided with a tail hook for installing a transmission.

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