Novel crank assembly for bicycle
By employing a concealed adjustment structure and a dual limiting mechanism, the problem of poor stability and difficult maintenance caused by the exposed design of existing bicycle crank assemblies has been solved, resulting in simplified assembly and improved stability.
Patent Information
- Application Number
- CN202520746530.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2026-02-17
- Estimated Expiration
- 2035-04-18
AI Technical Summary
Existing bicycle crank assemblies are susceptible to mud and water intrusion due to exposed preload rings and adjusting washers, resulting in poor stability, difficult maintenance, and complicated assembly for users, which is prone to errors.
It adopts a concealed adjustment structure, including a compensation sleeve, adjustment bolt, guide sleeve and connecting sleeve. Through the inclined surface fit and double limit mechanism, it blocks the intrusion path of mud and sand, and simplifies assembly and adjustment through built-in design.
It improves the long-term stability and ease of maintenance of bicycle crank assembly, reduces the impact of mud and sand accumulation, simplifies the assembly process, enables quick disassembly, and enhances the stability of drive shaft and user experience.
Smart Images
Figure CN223919508U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of bicycle technology, and specifically to a novel crank assembly for bicycles. Background Technology
[0002] Currently, conventional bicycle cranks have connector structures at the left and right free ends. In actual installation, the drive shaft first passes through the bottom bracket structure of the frame, and then the drive-side crank and the non-drive-side crank are installed at the left and right connector positions for limiting and fixing. Finally, in order to be compatible with the width specifications of the bottom bracket, the preload ring and thickness adjustment washer are often used to fill the gap between the left and right cranks and the bearings of the bottom bracket structure. This ensures the symmetrical alignment of the left and right cranks and prevents the cranks at both ends from shaking and making abnormal noises.
[0003] However, crank assemblies with preload rings and washers present a series of problems: Firstly, traditional preload rings and washers are completely exposed between the crank and the bottom bracket assembly, with their installation position located outside the crank arm. Since the exposed surfaces are in direct contact with the external environment, mud and water easily adhere to the preload ring and washers in rainy weather or on sandy roads. With continued riding, the preload ring or thickness adjustment washer is affected by axial movement, and sand particles can easily penetrate the gap between the two components, creating a "shim effect." This forcibly widens the clearance between the crank and the bottom bracket bearing, gradually leading to insufficient clearance and causing axial instability, shaking, and abnormal noise in the driveshaft. Therefore, the completely exposed design of the preload ring and washer structure makes it easy for external contaminants to come into direct contact during riding, compromising product stability and lifespan. Secondly, since the installation positions of the left and right cranks on the driveshaft are fixed according to the design position of the connector, in order to adapt to the width specifications of the bottom bracket and ensure the centering symmetry of the left and right cranks, the preload ring and washer thickness of the left and right cranks need to be adjusted independently. However, this kind of assembly fine-tuning usually requires professional operation. It is cumbersome and difficult for users to assemble themselves. Even if the assembly is completed, it is easy to produce errors and cause asymmetrical installation. This leads to inconsistent distances between the left and right cranks and the middle bottom bracket. In other words, asymmetrical left and right cranks can easily cause a significant difference in the force exerted by the left and right feet when riding, resulting in a deviation in riding posture and sports injuries over time. Thirdly, the setting of the preload ring and adjusting washer leaves very little space for user adjustment, and gap adjustment is time-consuming, laborious and inconvenient.
[0004] Therefore, existing new crank assemblies for bicycles urgently need improvement. Utility Model Content
[0005] The purpose of this utility model is to overcome the aforementioned defects or problems in the prior art and provide a novel crank assembly for bicycles. This assembly is not only simple in structure and easy to assemble, but also effectively blocks the path of mud and sand intrusion and eliminates axial clearance, thereby solving the problems of poor stability and difficult maintenance caused by the complete exposure of adjustment components in the prior art. To achieve the above objective, this utility model adopts the following technical solution:
[0006] A novel crank assembly for bicycles, characterized in that it comprises: a drive shaft that is inserted through the bottom bracket structure of the bicycle; the non-drive end of the drive shaft has a locking portion for fixing the non-drive side crank, and the drive end of the drive shaft has an axial threaded hole; a side crank structure, including a crank arm and a compensating sleeve, an adjusting bolt, a guide sleeve, and a connecting sleeve respectively built into the sleeve holes of the crank arm; the compensating sleeve is sleeved on the drive end of the drive shaft, and one end face of the compensating sleeve is used to support the bearing of the bottom bracket structure; the inner wall of the guide sleeve is threadedly engaged with the compensating sleeve and is used to drive the compensating sleeve and the connecting sleeve. Axial displacement of the sleeve; the inner wall of the connecting sleeve and the outer wall of the compensating sleeve are respectively provided with mutually adaptable inclined surfaces, and the inclination direction of each inclined surface extends outward from the guide sleeve toward the five-way structure; wherein, the guide sleeve rotates and its end face abuts against the end face of the connecting sleeve to drive the compensating sleeve to translate and support the bearing surface of the five-way structure, and pushes the connecting sleeve to move axially in the limited state of the compensating sleeve, so that the connecting sleeve restricts the retraction of the compensating sleeve in the radial and axial directions through the inclined surface; the adjusting bolt is screwed into the axial threaded hole of the transmission shaft and acts on the compensating sleeve to restrict the axial retraction and / or circumferential movement of the compensating sleeve.
[0007] Preferably, the sleeve portion of the compensation sleeve exposed in the crank arm has a retaining base sleeve, which is driven by axial force to hold the bearing surface of the bottom bracket structure; the retaining base sleeve is recessed with an annular groove in the axial direction.
[0008] Preferably, the adjusting bolt and the compensating sleeve are located inside the guide sleeve, and the adjusting bolt is located between the guide sleeve and the compensating sleeve; the free end of the adjusting bolt away from the axial screw hole has a double-sided ring, which extends outward along the radial direction of the adjusting bolt, so as to act on the guide sleeve to abut against it and drive it to rotate synchronously when the adjusting bolt is reversed and retracted, so as to disengage the guide sleeve from the end face of the connecting sleeve.
[0009] Preferably, the double-sided ring includes a positive end face acting on the compensating sleeve and a negative end face acting on the guiding sleeve, wherein the positive end face and the negative end face are parallel.
[0010] Preferably, the guide sleeve further includes a locking ring formed on the inner wall, wherein the outer diameter of the double-sided ring is larger than the inner diameter of the locking ring and the axes of the two coincide; the locking ring is used to act against the opposite end face of the double-sided ring to make the guide sleeve move synchronously with the adjusting bolt.
[0011] Preferably, the compensation sleeve includes a locking threaded sleeve, an inclined base sleeve, and a clamping base sleeve formed sequentially from left to right toward the drive shaft; wherein, the guide sleeve is configured on the locking threaded sleeve and threadedly engaged with it; the inclined base sleeve is configured as a spline sleeve, and the inner wall of the connecting sleeve is sleeved on the inclined base sleeve to form an anti-rotation constraint, and the inclined surfaces of the two engage with each other.
[0012] Preferably, a transition groove is recessed at the connection position between the locking screw sleeve and the inclined base sleeve.
[0013] Preferably, a coaxial receiving ring is also formed on the side of the connecting sleeve, the receiving ring being located between the connecting sleeve and the bottom bracket structure; the receiving ring corresponds to the abutment base sleeve, and its inner diameter is larger than the outer diameter of the abutment base sleeve; the receiving ring is used to cooperate with the limiting ring to constrain the crank arm between the crank arm and the bottom bracket structure, and to form an axial gap between the crank arm and the bottom bracket structure.
[0014] Preferably, the side crank structure further includes a cap screwed to the outside of the connecting sleeve, the cap being located on the side away from the bottom bracket structure; a stop ring is formed on the outer wall of the connecting sleeve, the crank arm is sleeved on the connecting sleeve and located between the connecting sleeve and the cap, so as to perform axial constraint and limitation through the cooperation of the cap and the connecting sleeve.
[0015] Preferably, the non-drive side crank and crank arm are equidistant from the bottom bracket structure, and are symmetrically arranged at the left and right ends of the bottom bracket structure.
[0016] 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:
[0017] (1) This utility model provides a novel crank assembly for bicycles, which is not only simple in structure and easy to assemble, but also effectively blocks the path of mud and sand intrusion and eliminates axial fit clearance, thereby solving the defects of poor stability and difficult maintenance caused by the complete exposure of adjustment components in the prior art. This utility model mainly designs a side crank structure, which has many functions. First, it has the functions of resisting mud and sand and preventing loosening. In the traditional case, the preload ring and adjusting washer are completely exposed between the crank arm and the bottom bracket structure, and mud and water can easily intrude into the bottom bracket system through the gap, resulting in increased clearance and decreased stability. This utility model integrates the main structure of the compensation sleeve, adjusting bolt, guide sleeve and connecting sleeve into the crank arm sleeve hole to form a non-exposed hidden adjustment structure, which significantly blocks the path of mud and sand intrusion into the core adjustment area. Compared with the traditional exposed design, the long-term stability is significantly improved and the product experience is better. Secondly, the dual limiting mechanism enhances reliability. The inclined surfaces of the connecting sleeve and the compensating sleeve adopt a bevel fit, which generates radial and axial forces that effectively confine the compensating sleeve to the side of the bottom bracket bearing, effectively preventing the compensating sleeve from rolling back axially, thus achieving the first limiting of the compensating sleeve. Secondly, the adjusting bolt is screwed into the axial threaded hole at the drive end. By tightening the adjusting bolt, axial displacement is achieved, directly supporting the compensating sleeve, thus achieving the second limiting of the compensating sleeve to eliminate axial clearance. This dual limiting mechanism greatly avoids drive shaft instability and abnormal noise caused by the compensating sleeve loosening, rolling back, or rotating. Thirdly, it is easy to adjust. If the user needs to adjust the axial clearance to ensure alignment, they can easily fine-tune it themselves by controlling the adjusting bolt and the guide sleeve, making maintenance convenient and very easy.
[0018] (2) In this technical solution, the bushing hole of the clamping base sleeve is exposed outside the crank arm, and the clamping base sleeve is recessed with an annular groove facing the axis. In this way, in the riding scenario, if external objects or fluids such as mud, sand, or water are sprayed onto the crank assembly, these objects or fluids are not easy to adhere to the surface of the crank assembly and will mostly be collected into the annular groove. Furthermore, as riding continues, centrifugal force will be generated, effectively throwing them out of the annular groove and emptying them. Thus, this product has a certain self-cleaning effect, and even if accumulation occurs, there is no need to disassemble the entire crank structure. Simply spraying the annular groove with a spray gun can quickly complete the cleaning. Therefore, compared with the traditional fully exposed preload ring and washer, the exposed area is reduced by more than 80%, and self-cleaning is achieved through centrifugal force, significantly reducing the impact of mud and sand accumulation on the adjustment area.
[0019] (3) In this technical solution, the disassembly efficiency is extremely high when it is necessary to loosen and disassemble the crank arm; it is only necessary to control the adjusting bolt to reverse and retract, and the reverse end face of the double-sided ring can directly press against the locking ring on the inner wall of the guide sleeve, driving the guide sleeve to rotate synchronously and disengage from the end face of the connecting sleeve. No additional rotational force needs to be applied to the guide sleeve to make it rotate synchronously. This linkage mechanism reduces the disassembly steps, requires no additional tools or step-by-step operations, and the entire side crank structure can be easily disassembled. Disassembly and assembly are convenient and quick, and maintenance efficiency is significantly improved.
[0020] (4) In this technical solution, the positive end face and the negative end face of the double-sided ring are parallel to ensure that the force transmission direction is consistent when the adjusting bolt is tightened or loosened, avoiding eccentric wear caused by the tilt of the end face and extending the service life of the component. Secondly, the parallel end face design makes the force distribution on the compensation sleeve and the guide sleeve uniform when the adjusting bolt moves axially, avoiding the problem of local stress concentration caused by inclined surface contact and improving the adjustment stability.
[0021] (5) In this technical solution, a transition groove is formed at the connection position between the locking screw sleeve and the inclined base sleeve. The transition groove can store air to avoid the vacuum adsorption effect during the locking process. Moreover, this design significantly reduces the disassembly resistance of the compensation sleeve and the guide sleeve, making maintenance time-saving, labor-saving, and easy to operate.
[0022] (6) In this technical solution, the receiving ring of the connecting sleeve cooperates with the limiting ring to constrain the chainring between the crank arm and the bottom bracket structure, forming an axial clearance. This design prevents the chainring from axially moving during high-speed riding, improves transmission efficiency, and reduces the risk of chain slippage.
[0023] (7) The non-drive side crank is fixed to the non-drive side of the drive shaft via a locking mechanism. Traditional solutions require separate adjustment of the preload rings and washers on both sides to ensure alignment, which is complex and prone to errors. This technical solution, through a single-sided adjustment design (only the drive side needs to be adjusted), can simultaneously ensure the symmetry of the non-drive side crank and the drive side crank relative to the bottom bracket structure, reducing the installation error rate and avoiding the risk of riding posture deviation and sports injuries caused by the asymmetry of the left and right cranks. Attached Figure Description
[0024] 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.
[0025] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;
[0026] Figure 2 This is a schematic diagram of the side crank structure and the drive shaft detached in an embodiment of the present invention;
[0027] Figure 3 This is a schematic cross-sectional view of an embodiment of the present utility model;
[0028] Figure 4 for Figure 3 A magnified view of a portion of the image;
[0029] Figure 5 This is a cross-sectional schematic diagram of the side crank structure and drive shaft assembly state according to an embodiment of the present utility model;
[0030] Figure 6 This is an exploded view of an embodiment of the present invention;
[0031] Figure 7 This is a schematic diagram of the adjusting bolt and compensating sleeve in an embodiment of this utility model.
[0032] The annotations in the attached figures are explained as follows:
[0033] 1. Drive shaft; 2. Side crank structure; 21. Crank arm; 22. Compensating sleeve; 221. Clamping base sleeve; 222. Locking screw sleeve; 223. Inclined base sleeve; 224. Transition groove; 22a. Annular groove; 23. Adjusting bolt; 231. Double-sided ring; 23a. Positive end face; 23b. Reverse end face; 24. Guide sleeve; 241. Locking ring; 25. Connecting sleeve; 251. Stop ring; 252. Receiving ring; 253. Limiting ring; 26. Cover; 3. Non-drive side crank; 4. Crankset. Detailed Implementation
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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".
[0039] Please see Figures 1 to 7 .
[0040] This invention provides a novel crank assembly for bicycles.
[0041] The crank assembly includes a drive shaft 1 and non-drive side cranks 3 and side crank structures 2 located at the left and right ends of the drive shaft 1; wherein, it includes:
[0042] See Figures 1 to 3
[0043] The drive shaft 1 is a hollow drive shaft with an internal core. It is connected to the bottom bracket structure of the bicycle through a plug-in connection. Both ends of the drive shaft 1 (non-drive end and drive end) protrude from the bottom bracket structure (not shown in the figure) on the left and right sides. The non-drive end of the drive shaft 1 is provided with a locking part for fixing the non-drive side crank 3. The locking part is mainly a spline connector or keyway, etc. The non-drive side crank 3 is fitted onto the locking part and pre-positioned. Then, the non-drive side crank 3 is completely fixed to the drive shaft 1 by interference fit, external adhesive or bolt tightening, etc. In this way, the axial movement and circumferential rotation of the non-drive side crank 3 are completely locked and limited, so that it can only rotate synchronously with the drive shaft 1. The drive end of the drive shaft 1 is provided with an axial screw hole. The axial screw hole extends along the axial direction of the drive shaft 1, and its axis coincides with the axis of the drive shaft 1.
[0044] See Figures 3 to 7 ,
[0045] The side crank structure 2 is mainly located at the drive end of the drive shaft 1. The side crank structure 2 includes a crank arm 21 and a compensation sleeve 22, an adjusting bolt 23, a guide sleeve 24, and a connecting sleeve 25, which are respectively built into the sleeve holes of the crank arm 21. That is, the compensation sleeve 22, the adjusting bolt 23, the guide sleeve 24, and the connecting sleeve 25 are all located in the sleeve holes of the crank arm 21 to form a non-exposed hidden adjustment structure. This can block the path of mud and sand intruding into the core adjustment area, and is less susceptible to the influence of external mud, sand, water and other factors, thus improving long-term stability.
[0046] In this embodiment, the compensating sleeve 22 is sleeved on the drive end of the drive shaft 1, and one end face of the compensating sleeve 22 is used to support the bearing of the bottom bracket structure (in the prior art, two bearings are installed on both sides of the bottom bracket structure to ensure that the crank bears the alternating pedaling force from the left and right sides when riding, and the two bearings can evenly distribute the radial and axial loads, avoid overload of one side bearing, and reduce the risk of wear and deformation). The guide sleeve 24 is threaded to the compensating sleeve 22 (the inner wall of the guide sleeve 24 and the outer wall of the compensating sleeve 22 have threads) and is used to drive the axial displacement of the compensating sleeve 22 and the connecting sleeve 25. The inner wall of the connecting sleeve 25 and the outer wall of the compensating sleeve 22 are respectively provided with mutually adaptable inclined surfaces, and the inclination direction of each inclined surface extends outward from the guide sleeve 24 toward the bottom bracket structure.
[0047] Specifically, in this embodiment, the guide sleeve 24 moves along the axial displacement of the compensation sleeve 22 by rotating on the threaded part of the compensation sleeve 22, with its end face abutting against the end face of the connecting sleeve 25. As it continues to move, the connecting sleeve 25 comes into contact with the inclined surface of the compensation sleeve 22, thereby driving the compensation sleeve 22 to translate and support the bearing surface of the five-way connector. At this time, when the compensation sleeve 22 is in a limited position and is supported, the guide sleeve 24 continues to rotate to push the connecting sleeve 25 to move axially. The inclined surface of the connecting sleeve 25 and the inclined surface of the compensation sleeve 22 continue to interact. The inner wall of the connecting sleeve 25 will be affected by the outer wall of the compensation sleeve 22 and will deform and expand radially to generate a radial constraint force. This achieves the restriction and suppression of the retraction of the compensation sleeve 22 by the inclined surface of the connecting sleeve 25 in the radial and axial directions, completing the first constraint (radial and axial constraint) on the compensation sleeve 22.
[0048] In this embodiment, the adjusting bolt 23 is screwed into the axial threaded hole of the transmission shaft 1. It moves axially by screwing and acts on the compensation sleeve 22 to further restrict the axial retraction and circumferential movement of the compensation sleeve 22. The adjusting bolt 23 provides a second limit (axial tightening) to realize a double limit mechanism to prevent the compensation sleeve 22 from retracting and rotating.
[0049] In this embodiment, the adjusting bolt 23 and the compensating sleeve 22 are located inside the guide sleeve 24, with the adjusting bolt 23 positioned between the guide sleeve 24 and the compensating sleeve 22. The free end of the adjusting bolt 23 away from the axial threaded hole has a double-sided ring 231. The double-sided ring 231 includes a positive end face 23a acting on the compensating sleeve 22 and a negative end face 23b acting on the guide sleeve 24. The positive end face 23a and the negative end face 23b are parallel. Furthermore, the double-sided ring 231 extends outward along the radial direction of the adjusting bolt 23. When the adjusting bolt 23 reverses and retracts, the negative end face 23b acts on the guide sleeve 24, pressing against it and driving it to rotate synchronously. This causes the guide sleeve 24 to rotate and retract synchronously with the compensating sleeve 22, thereby causing the guide sleeve 24 to disengage from the end face of the connecting sleeve 25, loosening the inclined fit, and eliminating the axial and radial constraint forces.
[0050] In this embodiment, the guide sleeve 24 further includes a locking ring 241 formed on the inner wall. The outer diameter of the double-sided ring 231 is larger than the inner diameter of the locking ring 241, and their axes coincide. The locking ring 241 is used to act and abut against the opposite end face 23b of the double-sided ring 231, so that the guide sleeve 24 and the adjusting bolt 23 move synchronously. Furthermore, the locking ring 241 can also be adapted to a special tool, that is, rotating it with a special tool can drive the guide sleeve 24 to rotate synchronously.
[0051] In this embodiment, the compensation sleeve 22 includes a locking screw sleeve 222, an inclined base sleeve 223, and a clamping base sleeve 221, which are integrally formed in sequence from left to right toward the drive shaft 1. The inclined base sleeve 223 is located between the clamping base sleeve 221 and the locking base sleeve, and the clamping base sleeve 221 is close to the bottom bracket structure. The clamping base sleeve 221 is exposed outside the sleeve hole of the crank arm 21. The clamping base sleeve 221 is part of the structure of the compensation sleeve 22. The clamping base sleeve 221 is driven by axial force to hold the bearing surface of the bottom bracket structure. The clamping base sleeve 221 is recessed with an annular groove 22a in the axial direction. In cycling scenarios, if external objects or fluids such as mud, sand, or water are sprayed onto the crank assembly, these objects or fluids are not easy to adhere to the surface of the crank assembly and will mostly be collected into the annular groove 22a. As you continue riding, centrifugal force will be generated, effectively throwing them out of the annular groove 22a and emptying them. In this way, this product achieves a certain self-cleaning effect through the annular groove 22a. Even if there is accumulation that cannot be cleaned, simply spraying the annular groove 22a with a spray gun can quickly clean it.
[0052] In this embodiment, the guide sleeve 24 is configured on the locking screw sleeve 222 and is threadedly engaged with each other; the inclined base sleeve 223 is configured as a spline sleeve, and the inner wall of the connecting sleeve 25 is sleeved on the inclined base sleeve 223 to form a rotation-stopping constraint, and the inclined surfaces of the two are engaged with each other.
[0053] In this embodiment, a transition groove 224 is recessed at the connection position between the locking screw sleeve 222 and the inclined base sleeve 223. The transition groove 224 can store a certain amount of air to avoid the vacuum adsorption effect during the locking process, thereby preventing resistance when disassembling the compensation sleeve 22 and the guide sleeve 24.
[0054] In this embodiment, the non-drive side crank 3 and crank arm 21 are equidistant from the bearings of the bottom bracket structure, so that they are symmetrically arranged at the left and right ends of the bottom bracket structure. The non-drive side crank 3 is fixedly mounted on the locking part of the drive shaft 1, so that the gap between the non-drive side crank 3 and the bottom bracket structure is always kept at a certain value. Thus, by adjusting the gap between the crank arm 21 and the bearing of the bottom bracket structure on one side, the crank arm 21 and the non-drive side crank 3 can remain symmetrical with the bottom bracket structure as the center. In this embodiment, the side crank structure 2 is a single-sided adjustment structure. When it is necessary to reduce the clearance in daily life, the user only needs to make a simple fine adjustment to the clearance adjustment bolt 23, which can easily ensure the symmetry of the two cranks. The daily fine adjustment function of the clearance adjustment bolt 23 is suitable for unidirectional reduction of axial clearance. The user can easily control the rotation of the clearance adjustment bolt 23 to achieve centering fine adjustment, which is simple and quick. If it is necessary to increase the clearance in daily life, the user only needs to control the clearance adjustment bolt and the guide sleeve to rotate in opposite directions to readjust the initial mating position of the guide sleeve and the compensation sleeve, which can complete the adjustment. Centering adjustment does not require professional operation and is not limited by space.
[0055] In this embodiment, the connecting sleeve portion exposes the sleeve hole of the crank arm 21. This exposed portion is the receiving ring 252, which is located near the bottom bracket structure. The receiving ring 252 is used to mount the crankset 4. The diameter of the receiving ring 252 is larger than the diameter of the base sleeve 221. The inner wall surface of the receiving ring 252 corresponds to the outer wall surface of the base sleeve 221. The inner wall surface of the receiving ring 252 is configured as a threaded wall. When the crankset 4 is placed on the receiving ring 252, a limiting ring 253 is mounted on the drive shaft 1 and forms a threaded connection with the threaded wall of the receiving ring 252. As the threads lock, the limiting ring 253 presses and limits the crankset 4, thereby constraining the crankset 4 between the crank arm 21 and the bottom bracket structure and creating an axial gap between the crankset 4 and the bottom bracket structure to ensure that the crankset 4 does not come into contact with the bottom bracket structure. In this embodiment, although the limiting ring 253 is also located between the drive shaft 1 and the bottom bracket structure, the limiting ring 253 will never come into contact with the bearing inside the bottom bracket structure after it is locked. Only the abutting base sleeve 221 will come into contact with the bearing.
[0056] In this embodiment, the side crank structure 2 further includes a cover 26 screwed to the outside of the connecting sleeve 25. The cover 26 is located on the side away from the bottom bracket structure. A stop ring 251 is formed on the outer wall of the connecting sleeve 25. The crank arm 21 is sleeved on the connecting sleeve 25 and located between the connecting sleeve 25 and the cover 26, so as to perform axial constraint and limitation through the cooperation of the cover 26 and the connecting sleeve 25.
[0057] In this embodiment, the outer diameter of the cover 26 has external threads, and the inner wall of the connecting sleeve 25 on the side away from the bottom bracket structure has internal threads. Therefore, during installation, the cover 26 is fitted onto the guide sleeve 24 and screwed onto the connecting sleeve 25, which also provides a certain limit for the guide sleeve 24. In this way, if the guide sleeve 24 becomes loose and moves backward, it can be restrained by the cover 26. After the cover 26 is locked, it will also abut against the crank arm 21 and cooperate with the stop ring 251 to lock the crank arm 21 and the connecting sleeve 25, preventing the crank arm 21 from detaching from the connecting sleeve 25.
[0058] In this embodiment, the drive side free end of the drive shaft 1 and the inner wall of the compensating sleeve 22, the outer wall of the inclined base sleeve 223 of the compensating sleeve 22 and the inner wall of the guide sleeve 24, the outer wall of the guide sleeve 24 and the inner wall of the crank arm 21 are all configured in a spline shape. In this way, after each component is installed, the circumferential rotation will be restricted; therefore, as long as the crank arm 21 rotates, it will drive each component to rotate synchronously.
[0059] Working principle and installation process of this utility model:
[0060] During installation,
[0061] First, install the non-drive side crank 3 onto the locking part of the non-drive side of the drive shaft 1; see [link / reference] Figure 2 Then, the entire side crank structure 2 is set on the drive side of the drive shaft 1 for installation.
[0062] Second, see Figures 2 to 4 First, bring the entire side crank structure 2 close to the drive side of the transmission shaft 1, then control the crank arm 21 to be sleeved on the drive side, so that the compensation sleeve 22 is sleeved and connected to the transmission shaft 1. At this time, the entire side crank structure 2 is pre-positioned on the transmission shaft 1.
[0063] Third, see Figure 4First, the locking ring 241 of the guide sleeve 24 is applied by a tool and the locking ring 241 is rotated, which causes the inner wall of the guide sleeve 24 to be screwed into the locking sleeve 222 of the compensation sleeve 22. As the rotational force is continued to be applied, the guide sleeve 24 moves along the axial displacement of the compensation sleeve 22, and its end face abuts against the end face of the connecting sleeve 25, causing the inclined surface of the inner wall of the connecting sleeve 25 to contact the inclined surface of the inclined base sleeve 223 of the compensation sleeve 22, so as to drive the compensation sleeve 22 to translate until the abutting base sleeve 221 of the compensation sleeve 22 abuts against the bearing surface of the five-way structure (not shown in the figure) and is positioned. At this time, the compensation sleeve 22 is in a limited position.
[0064] Fourth, continue to apply rotational force to the locking ring 241. The force exerted by the guide sleeve 24 on the connecting sleeve 25 gradually increases. The guide sleeve 24 pushes the connecting sleeve 25 to move axially, so that the inclined surface of the connecting sleeve 25 and the inclined surface of the inclined base sleeve 223 continue to interact. This causes the inner wall of the connecting sleeve 25 to be affected by the outer wall of the compensating sleeve 22 and deform radially, generating a radial constraint force. This achieves the restriction and suppression of the retraction and rotation of the compensating sleeve 22 by the inclined surface of the connecting sleeve 25 in the radial and axial directions, completing the first constraint on the compensating sleeve 22 (radial and axial constraint). That is, the inclined base sleeve 223 of the compensating sleeve 22 is simultaneously subjected to radial and axial forces.
[0065] Fifth, a tool is applied to the adjusting bolt 23; the tool is used to control the rotation of the adjusting bolt 23, and the adjusting bolt 23 begins to move along the axial direction of the drive shaft 1 until the positive end face 23a of the double-sided ring 231 of the adjusting bolt 23 acts on the locking sleeve 222 of the compensating sleeve 22, so that the compensating sleeve 22 is subjected to axial constraint force for the second time, that is, the locking sleeve 222 of the compensating sleeve 22 is subjected to axial force, thus completing the double limiting and suppression of the compensating sleeve 22 as a whole, effectively preventing the compensating sleeve 22 from retracting from the drive shaft 1 and from circumferential movement. At this time, the crank arm 21 is fixed to the drive side of the drive shaft 1 and maintains a certain gap relative to the bottom bracket structure.
[0066] When it is necessary to loosen and disassemble the crank arm 21, simply loosen the adjusting bolt 23. The adjusting bolt 23 will axially displace, and the reverse end face 23b of its double-sided ring 231 will press against the guide sleeve 24. The guide sleeve 24 will rotate synchronously under the action of the adjusting bolt 23 without any rotational force. In this way, the guide sleeve 24 and the adjusting bolt 23 will be completely loosened, and the crank arm 21 can be disassembled. Quick disassembly can be achieved by simply rotating the adjusting bolt 23, without having to loosen the adjusting bolt 23 and the guide sleeve 24 one by one. Therefore, this utility model is low in cost and can be assembled quickly. By replacing the traditional preload ring and adjusting washer with the compensating sleeve 22, it blocks the path of mud and sand intrusion and eliminates the axial fit clearance, solving the drawbacks caused by the use of preload rings and thickness adjusting washers in existing crank assemblies. This utility model not only reduces manufacturing costs and simplifies the assembly process, but also effectively blocks the path of mud and sand intrusion and eliminates the axial fit clearance, thereby solving the defects of poor stability and difficult maintenance caused by the complete exposure of the adjusting components in the prior art. This utility model mainly features a side crank structure 2, which has several functions. Firstly, it resists sediment and prevents loosening. Traditionally, the preload ring and adjusting washer are completely exposed between the crank arm 21 and the bottom bracket structure (not shown), allowing sediment and water to easily penetrate the central shaft system through the gaps, leading to increased clearance and decreased stability. This utility model integrates the main structure of the compensating sleeve 22, adjusting bolt 23, guide sleeve 24, and connecting sleeve 25 within the crank arm 21 sleeve hole, forming a non-exposed, concealed adjusting structure. This significantly blocks the path of sediment intrusion into the core adjusting area. Compared to the traditional exposed design, long-term stability is significantly improved, resulting in a better user experience. Secondly, the dual limiting mechanism enhances reliability. The inclined surfaces of the connecting sleeve 25 and the compensating sleeve 22 adopt a bevel fit. The resulting radial and axial forces effectively limit the compensating sleeve 22 to the side of the bottom bracket bearing, effectively preventing the compensating sleeve 22 from retracting axially, thus achieving the first limiting of the compensating sleeve 22. Secondly, the adjusting bolt 23 is screwed into the axial threaded hole at the drive end. By tightening the adjusting bolt 23, axial displacement is achieved, directly supporting the compensating sleeve 22, thus achieving the second limiting of the compensating sleeve 22 to eliminate axial clearance. This dual limiting mechanism can greatly avoid the instability and abnormal noise of the drive shaft caused by the compensating sleeve 22 loosening, retraction, or rotation. Thirdly, it is easy to adjust. If the user needs to adjust the axial clearance to ensure alignment, they can easily fine-tune it by controlling the adjusting bolt 22 and the guide sleeve 24, making maintenance convenient and very easy.
[0067] 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 novel crank assembly for bicycles, characterized in that, include: A drive shaft is inserted through the bottom bracket of a bicycle; the non-drive end of the drive shaft is provided with a locking part for fixing the non-drive side crank, and the drive end of the drive shaft is provided with an axial threaded hole. A side crank structure includes a crank arm and a compensating sleeve, an adjusting bolt, a guide sleeve, and a connecting sleeve, each housed in a hole in the crank arm. The compensating sleeve is fitted onto the drive end of the drive shaft, and one end face of the compensating sleeve is used to support the bearing of the bottom bracket structure. The inner wall of the guide sleeve is threaded into the compensating sleeve and is used to drive the axial displacement of the compensating sleeve and the connecting sleeve. The inner wall of the connecting sleeve and the outer wall of the compensating sleeve are respectively provided with mutually adaptable inclined surfaces, and the inclination direction of each inclined surface extends outward from the guide sleeve toward the bottom bracket structure. The guide sleeve rotates and its end face abuts against the end face of the connecting sleeve to drive the compensating sleeve to translate and support the bearing surface of the bottom bracket structure. In the limited state of the compensating sleeve, the guide sleeve pushes the connecting sleeve to move axially, so that the connecting sleeve restricts the retraction of the compensating sleeve in the radial and axial directions through the inclined surfaces. The adjusting bolt is screwed into the axial threaded hole of the drive shaft and acts on the compensation sleeve to limit the axial retraction and / or circumferential movement of the compensation sleeve.
2. A novel crank assembly for a bicycle as described in claim 1, characterized in that, The adjusting bolt and the compensating sleeve are located inside the guide sleeve, and the adjusting bolt is located between the guide sleeve and the compensating sleeve. The free end of the adjusting bolt away from the axial screw hole has a double-sided ring, which extends outward along the radial direction of the adjusting bolt. When the adjusting bolt is reversed and retracted, it acts on the guide sleeve to abut against it and drive it to rotate synchronously, so that the guide sleeve is disengaged from the end face of the connecting sleeve.
3. A novel crank assembly for a bicycle as described in claim 2, characterized in that, The double-sided ring includes a positive end face that acts on the compensating sleeve and a negative end face that acts on the guiding sleeve, wherein the positive end face and the negative end face are parallel.
4. A novel crank assembly for a bicycle as described in claim 3, characterized in that, The guide sleeve also includes a locking ring formed on the inner wall. The outer diameter of the double-sided ring is larger than the inner diameter of the locking ring, and their axes coincide. The locking ring is used to act against the opposite end face of the double-sided ring to make the guide sleeve move synchronously with the adjusting bolt.
5. A novel crank assembly for a bicycle as described in any one of claims 1 to 4, characterized in that, The sleeve hole of the compensation sleeve exposed on the crank arm includes a clamping base sleeve, which is driven by axial force to hold the bearing surface of the bottom bracket structure; the clamping base sleeve is recessed with an annular groove in the axial direction.
6. A novel crank assembly for a bicycle as described in claim 5, characterized in that, The compensation sleeve includes a locking threaded sleeve, an inclined base sleeve, and a clamping base sleeve formed sequentially from left to right toward the drive shaft; wherein, the guide sleeve is configured on the locking threaded sleeve and threadedly engaged with it; the inclined base sleeve is configured as a spline sleeve, and the inner wall of the connecting sleeve is sleeved on the inclined base sleeve to form an anti-rotation constraint, and the inclined surfaces of the two engage with each other.
7. A novel crank assembly for a bicycle as described in claim 6, characterized in that, A transition groove is recessed at the connection position between the locking nut and the inclined base sleeve.
8. A novel crank assembly for a bicycle as claimed in claim 1, characterized in that, The side crank structure also includes a cap screwed to the outside of the connecting sleeve, the cap being located on the side away from the bottom bracket structure; a stop ring is formed on the outer wall of the connecting sleeve, the crank arm is sleeved on the connecting sleeve and located between the connecting sleeve and the cap, so as to perform axial constraint and limitation through the cooperation of the cap and the connecting sleeve.
9. A novel crank assembly for a bicycle as claimed in claim 6, characterized in that, The connecting sleeve also has a coaxial receiving ring on its side, which is located between the connecting sleeve and the bottom bracket structure. The receiving ring corresponds to the abutment base sleeve, and its inner diameter is larger than the outer diameter of the abutment base sleeve. The receiving ring is used to cooperate with the limiting ring to constrain the crank arm between the crank arm and the bottom bracket structure, and to form an axial gap between the crank arm and the bottom bracket structure.
10. A novel crank assembly for a bicycle as claimed in claim 1, characterized in that, The non-driving side crank and crank arm are equidistant from the bottom bracket structure, and are symmetrically arranged at the left and right ends of the bottom bracket structure.