A self-retracting crank mechanism for bicycles

Abstract

This utility model discloses a crank self-retracting device for bicycles, including an inner pressure plate, an outer pressure plate, and several connecting parts for locking the inner and outer pressure plates. The inner pressure plate is attached to the side wall of the chainring in the crank assembly, and has multiple connecting cylinders extending towards the outer pressure plate. The outer pressure plate is located on the outside of the bicycle crank, and has a clamping part on the side facing the crank for abutting against the self-retracting cover in the crank assembly. The outer pressure plate also has multiple through holes corresponding to each of the connecting cylinders. This utility model's technical solution is simple in structure, easy to install, easy to implement, and low in cost. It solves the problem in existing bicycles where, during crank disassembly, the spline connection between the crank and crank axle is too tight, causing the self-retracting cover and crank threaded connection to fail, thus preventing the crank from being disassembled from the crank axle synchronously with the self-retracting cover.

Description

Technical Field

[0001] This utility model relates to the field of bicycle accessories technology, specifically to a crank self-retracting device for bicycles. Background Technology

[0002] In a bicycle's drivetrain, the crank, as a key component connecting the bottom bracket and pedals, directly impacts the bicycle's maintenance efficiency due to the ease of its assembly and disassembly. Currently, see... Figure 1 The connection between the crank A4 and the bottom bracket A3 of existing bicycles mostly adopts a spline fit structure and is equipped with a self-removing disassembly mechanism. The core components of this mechanism include the bolt A5 inside the bottom bracket and the self-removing cover A2 which is screwed to the crank.

[0003] The specific disassembly process is as follows: When it is necessary to detach the crank from the bottom bracket, the operator uses a tool to loosen bolt A5 inside the bottom bracket. During the loosening process, bolt A5 will move axially outward along the crank bottom bracket A3, and during this movement, the end of bolt A5 will press against the inner end face of the self-retracting cover A2. Since the self-retracting cover A2 and the crank A4 are fixed by a threaded connection, the axial thrust continuously applied by bolt A5 will drive the self-retracting cover A2 to move synchronously outward along the crank A4. Then, through the threaded engagement force between the self-retracting cover A2 and the crank A4, the crank A4 as a whole will be disengaged from the spline connection of the crank bottom bracket A3, ultimately achieving the separation of crank A4 from the crank bottom bracket A3.

[0004] However, during actual disassembly, the existing structure has obvious defects: in order to ensure the stability of the crank and bottom shaft transmission, the spline connection between the crank and the bottom shaft may jam due to excessive locking force or long-term use; and the connection between the self-retracting cover and the crank relies solely on threaded engagement, the threaded connection strength of which is limited by factors such as thread specifications, material strength and assembly torque, and is often lower than the connection strength of the spline connection.

[0005] Therefore, when an operator loosens the bolts in the crank assembly and pushes the self-retracting cover with the bolts, if the resistance at the spline connection is greater than the thread strength between the self-retracting cover and the crank, the threaded connection between the self-retracting cover and the crank will directly fail (e.g., the threads will strip). This causes the self-retracting cover to be pushed out of the crank by the bolts alone, while the crank remains firmly fixed to the spline on the bottom bracket and cannot detach from the bottom bracket synchronously with the self-retracting cover. As can be seen, the above-mentioned problem not only prevents the crank from being disassembled but may also damage components such as the self-retracting cover and bolts, increasing maintenance costs and operational difficulty, and seriously affecting the convenience and efficiency of bicycle maintenance. Utility Model Content

[0006] This utility model provides a crank self-unwinding device for bicycles, which is simple in structure, easy to install, easy to implement, and low in cost. It solves the problem that in existing bicycles, when the crank is disassembled, the spline connection between the crank and the crank shaft is too tight, causing the threaded connection between the self-unwinding cover and the crank to fail, thus preventing the crank from being disassembled from the crank shaft synchronously with the self-unwinding cover. The main technical solution is as follows:

[0007] A crank self-retracting device for a bicycle includes an inner pressure plate, an outer pressure plate, and several connecting members for locking the inner and outer pressure plates. The inner pressure plate is attached to the side wall of the chainring in the crank assembly and has multiple connecting cylinders extending towards the outer pressure plate. The outer pressure plate is located on the outside of the bicycle crank and has a clamping portion on its crank-facing side for abutting against a self-retracting cover in the crank assembly. The outer pressure plate also has multiple through holes corresponding to each connecting cylinder. The axis of the connecting cylinder is coaxial with the axis of the corresponding through hole on the outer pressure plate. Connecting members pass through the through holes in the outer pressure plate and are detachably screwed to the connecting cylinders. Tightening the connecting members reduces the distance between the inner and outer pressure plates, causing the clamping portion of the outer pressure plate to press against the outer end face of the self-retracting cover and constraining the self-retracting cover to the crank.

[0008] Preferably, the extension height of the connecting cylinder is greater than the depth of the mounting hole on the toothed plate, and each connecting cylinder is respectively inserted through each mounting hole on the toothed plate; the axis of each through hole is coaxial with the axis of each mounting hole on the toothed plate.

[0009] Preferably, the connecting cylinder does not pass through the mounting hole on the dental disc, and the connecting cylinder is located on the outer periphery of the dental disc.

[0010] Preferably, the connector is configured as a bolt, and the inner wall of the connecting cylinder is provided with an internal thread adapted to the bolt.

[0011] Preferably, the abutting part is a protrusion protruding from the surface of the outer pressure plate, and the abutting surface of the protrusion is adapted to the shape of the outer end face of the self-retracting cover.

[0012] Preferably, the inner pressure plate includes at least two independent base plates, each of which is distributed on the upper and lower sides or the left and right sides of the crankshaft of the bicycle.

[0013] Preferably, the inner pressure plate is arranged in a "C" shape, and its opening is used to avoid the bottom crank of the bicycle.

[0014] Preferably, the inner pressure plate has an anti-slip structure on one end face facing the toothed plate, the anti-slip structure being raised anti-slip textures or a rubber pad.

[0015] As can be seen from the above description of this utility model, compared with the prior art, this utility model has the following beneficial effects:

[0016] (1) This utility model provides a crank self-retracting device for bicycles, which has a simple structure, is easy to install, is easy to implement and has low cost. It solves the problem that when disassembling the crank of an existing bicycle, the self-retracting cover fails to connect with the crank thread due to the excessive tightness of the spline connection between the crank and the crank shaft, and thus the crank cannot be disassembled from the crank shaft synchronously with the self-retracting cover. The technical solution of this utility model reduces the gap between the inner pressure plate and the outer pressure plate by locking the connecting part and the connecting cylinder to form a clamping effect, so that the outer pressure plate can firmly press and constrain the self-retracting cover on the crank, thereby converting the axial thrust of the bolt in the crank assembly on the self-retracting cover into the thrust on the entire crank assembly, avoiding the phenomenon of the self-retracting cover being pushed out alone and the thread stripping due to insufficient bolt strength, and effectively preventing the self-retracting cover from loosening from the crank. Therefore, the installation of this device can be completed simply by tightening the connecting parts with conventional tools. Afterwards, the crank can be automatically disassembled simply by turning the bolts. The disassembly process is no different from conventional methods, which can effectively improve the success rate and reliability of the crank's automatic disassembly and reduce the difficulty and cost of daily maintenance.

[0017] (2) In this technical solution, the connecting cylinder is respectively connected through the mounting holes on the crank, which ensures that after the outer pressure plate and the inner pressure plate are locked, the pressing part on the outer pressure plate and the self-retracting cover are precisely aligned without misalignment, thus eliminating the need for alignment adjustment. This ensures that the force of the pressing part can be evenly distributed to the self-retracting cover for stress diffusion, effectively preventing the self-retracting cover from tilting after being subjected to local forces. Secondly, the connecting cylinder being connected through the mounting holes also prevents the inner pressure plate from shifting towards its outer periphery. Therefore, this crank self-retracting device uses the mounting holes on the crank to achieve precise and rapid alignment of the pressing part relative to the self-retracting cover, making installation convenient and eliminating the need for additional positioning steps. This effectively achieves limiting and improves installation efficiency.

[0018] (3) In this technical solution, the inner pressure plate is set as at least two independent base plates. Specifically, since the surrounding structure of the crank shaft is complex and the space is small, the use of split base plates can be flexibly placed and assembled from the top and bottom or left and right sides, which greatly improves the installation convenience and scene adaptability of the device. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1This is a schematic diagram of the existing crankshaft during disassembly and assembly.

[0021] Figure 2 This is a schematic diagram of the overall structure of the crank self-retracting device according to an embodiment of the present utility model;

[0022] Figure 3 This is an exploded view of the crank self-retracting device according to an embodiment of this utility model;

[0023] Figure 4 This is a schematic diagram of the crank self-retracting device before use, according to an embodiment of this utility model.

[0024] Figure 5 This is a schematic diagram of the crank self-retracting device after assembly according to an embodiment of the present utility model;

[0025] Figure 6 for Figure 5 Overall sectional view.

[0026] The annotations in the attached figures are explained as follows:

[0027] A1, crankset; A11, mounting hole; A2, self-retracting cover; A3, crank shaft; A4, crank; A5, bolt; 1, inner pressure plate; 11, base plate; 12, connecting cylinder; 2, outer pressure plate; 21, clamping part; 22, through hole; 3, connector. Detailed Implementation

[0028] 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 preferred embodiments of the present utility model and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0029] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and drawings of this utility model is for distinguishing different objects and not for describing a specific order.

[0030] Unless otherwise expressly defined, in the claims, description, and accompanying drawings of this utility model, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing this utility model and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific protection scope of this utility model.

[0031] Unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" used in the claims, description and drawings of this utility model shall be interpreted broadly to refer to any connection in which there is no displacement or relative rotation relationship between the two parties, including non-removable fixed connection, detachable fixed connection, integral connection and fixed connection through other devices or components.

[0032] In the claims, description and accompanying drawings of this utility model, the terms "comprising", "having", and variations thereof are used to mean "including but not limited to".

[0033] This embodiment provides a self-unwinding device for a bicycle crank A4. It features a simple structure, easy installation, convenient implementation, and low cost. It solves the problem in existing bicycles where, during crank A4 removal, the spline connection between crank A4 and crank shaft A3 is too tight, causing the threaded connection between the self-unwinding cover A2 and crank A4 to fail, thus preventing crank A4 from being simultaneously removed from crank shaft A3 along with the self-unwinding cover A2. For details, see [link to documentation]. Figure 1 The existing structural diagram for disassembling and assembling crank A4 shows the following structure: crank A4 is fitted onto the spline connection of crank shaft A3 and interlocks with it; bolt A5 is located on the right free end of crank shaft A3 and is threadedly connected to it to restrict the axial movement of crank A4; self-retracting cover A2 is located outside bolt A5 and is installed inside the sleeve hole of crank A4 and threadedly connected to the sleeve hole to prevent it from falling off.

[0034] When it is necessary to detach crank A4 from crank axle A3, as described in the background section above, during the loosening of bolt A5, bolt A5 will press against the inner end face of self-retracting cover A2. As bolt A5 moves axially, it causes self-retracting cover A2 to move outward. Due to the threaded connection between self-retracting cover A2 and crank A4, crank A4 and self-retracting cover A2 will simultaneously detach from the spline connection of crank axle A3, thus achieving simultaneous removal of crank A4 from the bicycle. However, in reality, with long-term use of the bicycle or improper tightening force, the tightening force at the spline connection between crank A4 and crank axle A3 may exceed the threaded connection force between self-retracting cover A2 and crank A4. As bolt A5 moves axially, the threaded connection between self-retracting cover A2 and crank A4 will gradually fail. At this point, self-retracting cover A2 will be pushed out along with bolt A5, while crank A4 remains on crank axle A3, and the purpose of removing crank A4 cannot be achieved. Therefore, the crank A4 self-retracting device of this utility model is required to achieve the purpose of disassembling and assembling the crank A4.

[0035] First Embodiment

[0036] See Figures 2 to 5 ,

[0037] In this embodiment, it mainly includes an inner pressure plate 1, an outer pressure plate 2, and several connecting pieces 3 for locking the inner pressure plate 1 and the outer pressure plate 2; wherein,

[0038] The inner pressure plate 1 is attached to the side wall of the chainring A1 in the crank assembly A4. The inner pressure plate 1 has multiple connecting cylinders 12 extending towards the outer pressure plate 2, and the inner walls of the connecting cylinders 12 are threaded. The inner pressure plate 1 includes at least two independently designed base plates 11, each with two connecting cylinders 12. Each base plate 11 is distributed on the upper and lower sides or left and right sides of the crank axle A3 of the bicycle. This allows the two base plates 11 to flexibly avoid the crank axle A3 of the bicycle, and the two connecting cylinders 12 on the base plates 11 can quickly pass through the two mounting holes A11 on the chainring A1. In other embodiments, the inner pressure plate 1 can also be arranged in a "C" shape, with its opening used to avoid the crank axle A3 of the bicycle.

[0039] An outer pressure plate 2 is disposed on the outside of the crank A4 of the bicycle. The side of the outer pressure plate 2 facing the crank A4 is provided with a pressing part 21 for abutting against the self-retracting cover A2 in the crank A4 assembly. The pressing part 21 is a boss protruding from the plate surface of the outer pressure plate 2, and the abutting surface of the boss is adapted to the shape of the outer end face of the self-retracting cover A2. The outer pressure plate 2 is also provided with a plurality of through holes 22 corresponding to each connecting cylinder 12. The axis of the connecting cylinder 12 is coaxial with the axis of the corresponding through holes 22 on the outer pressure plate 2.

[0040] Connector 3, which is configured to mate with the internal threads of the inner wall of the connecting cylinder 12, see [reference]. Figure 6 The connector 3 passes through the through hole 22 of the outer pressure plate 2 and is detachably screwed to the inner wall of the connecting cylinder 12. By tightening the connector 3, the distance between the inner pressure plate 1 and the outer pressure plate 2 is reduced, and the inner pressure plate 1 and the outer pressure plate 2 will form a clamping force, so that the pressing part 21 of the outer pressure plate 2 presses against the outer end face of the self-retracting cover A2 and constrains and fixes the self-retracting cover A2 to the crank A4. In this way, since the self-retracting cover A2 is completely constrained and fixed to the crank A4, even if the threaded connection between the self-retracting cover A2 and the crank A4 completely fails, the self-retracting cover A2 will not detach from the crank A4.

[0041] In this embodiment, the extension height of the connecting cylinder 12 is greater than the depth of the mounting hole A11 on the toothed plate A1, so that the connecting cylinder 12 can pass through the mounting hole A11 on the toothed plate A1; the axis of each through hole 22 is coaxial with the axis of each mounting hole A11 on the toothed plate A1.

[0042] In this embodiment, the abutting part 21 is a boss structure. This boss structure can fully contact the entire outer end face of the self-retracting cover A2, avoiding local plastic deformation or damage that may be caused by point contact or small area contact, thus preventing the self-retracting cover A2 from tilting. Secondly, the abutting surface of the boss structure is adapted to the shape of the outer end face of the self-retracting cover A2, which can better fit the self-retracting cover A2, prevent the tool from slipping during the pressing or disassembly process, and ensure that the force can be effectively transmitted.

[0043] In this embodiment, the inner pressure plate 1 has an anti-slip structure (not shown) on the side face of the toothed disc A1. The anti-slip structure is a raised anti-slip texture or a rubber pad. This anti-slip structure can effectively prevent the inner pressure plate 1 from sliding relative to the side wall of the toothed disc A1 during the clamping process, ensuring the stability and reliability of the entire device under force.

[0044] The working principle and usage of this utility model are as follows: By enhancing the connection rigidity between the self-retracting cover A2 and the crank A4, the problem of the self-retracting cover A2 detaching independently during disassembly is solved. It utilizes the inner pressure plate 1 and the outer pressure plate 2 to form a clamping force, and the connecting piece 3 firmly presses the self-retracting cover A2 onto the crank A4, forming a temporary rigid unit. When the bolt A5 on the crank shaft A3 is loosened, the axial thrust of the bolt A5 on the self-retracting cover A2 is effectively transmitted to the entire chainring A1 and crank A4 through this device, thereby overcoming the resistance of the splined portion of the crank A4 and crank shaft A3, and pulling out the crank A4 and the self-retracting cover A2 together. Specifically,

[0045] During installation, please refer to Figure 4First, two base plates 11 are respectively placed on the side wall of the crankset A1, and the connecting cylinders 12 on the base plates 11 pass through the mounting holes A11 on the crankset A1, so that the base plates 11 are pre-positioned on the crankset A1. Next, the outer pressure plate 2 is placed on the outside of the crankset A4, and four connecting pieces 3 are respectively passed through the through holes 22 of the outer pressure plate 2 and screwed to the corresponding connecting cylinders 12. Finally, by rotating each connecting piece 3, the connecting piece 3 drives the outer pressure plate 2 to move towards the inner pressure plate 1, so as to reduce the distance between the outer pressure plate 2 and the inner pressure plate 1, until the abutting part 21 on the outer pressure plate 2 abuts against the outer end face of the self-retracting cover A2, so as to press and constrain the self-retracting cover A2 onto the crankset A4. At this time, the self-retracting cover A2 is firmly constrained and fixed onto the crankset A4, and this device and the crankset A4 assembly form a temporary rigid whole for disassembly.

[0046] When disassembling crank A4, use an external tool to rotate bolt A5 on crank shaft A3. This causes bolt A5 to move axially, creating a thrust on self-retracting cover A2. Since self-retracting cover A2 is rigidly fixed by this device, this thrust is converted into an axial pulling force on the entire crank A4 assembly (including chainring A1 and crank A4) through outer pressure plate 2, connecting piece 3, and inner pressure plate 1. This allows the self-retracting cover A2, along with crank A4, to be detached from crank shaft A3. After the crank A4 assembly is successfully detached, loosen and remove connecting piece 3 to separate the device from the crank A4 assembly. Therefore, its structure is simple, easy to install, easy to implement, and low in cost. It solves the problem that when disassembling crank A4 on existing bicycles, the spline connection between crank A4 and crank shaft A3 is too tight, causing the threaded connection between the self-retracting cover A2 and crank A4 to fail, and thus crank A4 cannot be disassembled from crank shaft A3 synchronously with the self-retracting cover A2. The technical solution of this utility model reduces the distance between the inner pressure plate 1 and the outer pressure plate 2 by locking the connecting piece 3 and the connecting cylinder 12 to form a clamping effect, so that the outer pressure plate 2 can firmly press and constrain the self-retracting cover A2 onto crank A4. This transforms the axial thrust of the bolt A5 in the crank A4 assembly onto the self-retracting cover A2 into a thrust on the entire crank A4 assembly, avoiding the phenomenon of the self-retracting cover A2 being pushed out separately and the thread stripping due to insufficient thread strength, and effectively preventing the self-retracting cover A2 from loosening from crank A4. Therefore, the installation of this device can be completed simply by tightening the connector 3 with conventional tools. Afterwards, the crank A4 can be automatically disassembled simply by turning the bolt A5. The disassembly process is no different from the conventional method, which can effectively improve the success rate and reliability of the crank A4's automatic disassembly and reduce the difficulty and cost of daily maintenance.

[0047] Second Embodiment

[0048] The difference between the second embodiment and the first embodiment is that the connecting cylinder 12 of the first embodiment passes through the mounting hole A11 on the crank A1; while the connecting cylinder 12 of this embodiment does not pass through the mounting hole A11 on the crank A1, and the connecting cylinder 12 is located on the outer periphery of the crank A1. Therefore, the connecting cylinder 12 of this embodiment does not need to pass through the mounting hole A11 on the crank A1. That is, the crank A4 self-retracting device of this embodiment does not need to utilize the mounting hole A11 on the crank A1. That is, each connecting cylinder 12 does not need to be designed to correspond to each mounting hole A11 on the crank A1, reducing the design and processing difficulty. It can be seen that the distance between the inner pressure plate 1 and the outer pressure plate 2 can be reduced without utilizing the crank A1, so that the pressing part 21 on the outer pressure plate 2 also abuts against the outer end face of the self-retracting cover A2.

[0049] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this utility model, but does not constitute a limitation on the scope of protection of this utility model. Modifications, equivalent substitutions, or other improvements to the embodiments of this utility model or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this utility model or the foregoing embodiments, should all be included within the scope of protection of this utility model.

Claims

1. A crank self-reversing device for bicycles, characterized in that: It includes an inner pressure plate, an outer pressure plate, and several connecting members for locking the inner and outer pressure plates; wherein, An inner pressure plate is attached to the side wall of the crankset in the crank assembly, and the inner pressure plate is provided with a plurality of connecting cylinders extending toward the outer pressure plate; An outer pressure plate is provided on the outside of the bicycle crank, and the side of the outer pressure plate facing the crank has a clamping part for abutting against the self-retracting cover in the crank assembly; the outer pressure plate also has a plurality of through holes corresponding to each of the connecting cylinders; the axis of the connecting cylinder is coaxial with the axis of the corresponding through hole on the outer pressure plate. A connector, which passes through the perforation of the outer pressure plate and is detachably screwed to the connecting cylinder, reduces the gap between the inner pressure plate and the outer pressure plate by tightening the connector, so that the pressing part of the outer pressure plate presses against the outer end face of the self-retracting cover and constrains and fixes the self-retracting cover to the crank.

2. The crank self-unwinding device as described in claim 1, characterized in that: The extension height of the connecting cylinder is greater than the depth of the mounting hole on the toothed plate, and each connecting cylinder is respectively inserted through each mounting hole on the toothed plate; the axis of each through hole is coaxial with the axis of each mounting hole on the toothed plate.

3. The crank self-unwinding device as described in claim 1, characterized in that: The connecting cylinder does not pass through the mounting hole on the toothed plate, and the connecting cylinder is located on the outer periphery of the toothed plate.

4. The crank self-retracting device as described in claim 1, characterized in that: The connector is configured as a bolt, and the inner wall of the connecting cylinder is provided with an internal thread adapted to the bolt.

5. The crank self-unwinding device as described in claim 1, characterized in that: The abutting part is a protrusion protruding from the surface of the outer pressure plate, and the abutting surface of the protrusion is adapted to the shape of the outer end face of the self-retracting cover.

6. The crank self-unwinding device as described in any one of claims 1-5, characterized in that: The inner pressure plate includes at least two independent base plates, each of which is distributed on the upper and lower sides or the left and right sides of the crankshaft of the bicycle.

7. The crank self-unwinding device as described in any one of claims 1-5, characterized in that: The inner pressure plate is C-shaped, and its opening is used to avoid the bottom crankshaft of the bicycle.

8. The crank self-unwinding device as described in claim 1, characterized in that: The inner pressure plate has an anti-slip structure on one end face facing the gear plate, which is a raised anti-slip texture or a rubber pad.

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