Locking structure of bicycle crank

Abstract

The utility model discloses a locking structure of a bicycle crank, which is used for locking the crank on a crank middle shaft of a bicycle, and is characterized in that the locking structure comprises a connecting sleeve which is matched with the crank middle shaft in a sleeving manner and is used for pre-positioning the crank on the crank middle shaft; the inner peripheral wall part of the connecting sleeve obliquely extends in the axial direction to form a section of inclined wall, the inclined wall extends to the opening of the connecting sleeve, and a locking space is formed in the inner peripheral wall relative to the locking head of the crank middle shaft; according to the technical scheme, the locking sleeve, the connecting sleeve and the crank form a whole, external acting force is resisted through the whole, the capacity of resisting the external force is higher, the structure is firmer, the locking effect of the crank is more stable, larger external impact force can be borne, the crank is prevented from falling off or shaking, and the service life of the crank is prolonged. And during daily riding, worries are avoided, the later maintenance cost is reduced, and the experience feeling is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of bicycles, in particular to a locking structure of a bicycle crank. Background Art

[0002] As an important transmission component of a bicycle, a bicycle crank plays a vital role in the riding experience. When the existing bicycle crank is locked on the crank shaft of the bicycle (see Figure 1 ), first, a locking sleeve in the form of a hexagon socket bolt is inserted into the crank shaft for threaded connection, and an axial force is applied to the stop portion of the connecting sleeve to press it against the crank shaft for constraint and fixation, so that the connecting sleeve provides pre-positioning for the crank; then, the crank sleeve is arranged on the connecting sleeve and the crank shaft for pre-positioning and installation; finally, the pressure plate is fixed to the connecting sleeve by bolts to constrain and fix the crank axially, completing the installation of the crank and the crank shaft; when disassembly and assembly is required, only the threaded fit between the locking sleeve and the crank shaft needs to be released, and the entire crank can be disassembled in a self-retracting manner.

[0003] Although this traditional bicycle crank structure can achieve the installation effect and is relatively convenient for later disassembly, it is also found in its actual operation and use that: the crank has a certain vibration phenomenon during the pedaling process, and the frequently generated vibration impact force will first be transmitted radially from the crank to the connecting sleeve. Since there is no reaction force between the connecting sleeve and the locking sleeve to resist the radial impact force, the connecting sleeve can only resist the impact force alone on the crank shaft, and constantly vibrates between the locking sleeve and the crank shaft, and directly rubs with the locking sleeve to transmit the axial reaction force to it, resulting in a connection gap between the two. The threaded connection between the crank shaft and the locking sleeve is inevitably loose, and the locking sleeve gradually retreats axially to make the axial constraint force invalid, and the crank shakes or falls off. Noise and abnormal sounds are likely to occur during riding, and there is a risk of the crank falling off, posing a certain safety hazard. Therefore, this type of traditional bicycle crank structure that only has axial constraint force is too dependent on the axial constraint force. As long as the axial constraint force decreases slightly, the entire crank will begin to shake. The overall structure has a weak ability to resist external forces, is not strong, and the locking effect is not stable enough, which greatly affects the riding experience of the bicycle.

[0004] In summary, the locking structure of the existing bicycle crank needs to be further improved and enhanced. Utility Model Content

[0005] The utility model provides a locking structure of a bicycle crank, which can not only constrain the crank axially, but also constrain it radially, and improve the structural firmness through double constraints, so that the locking effect of the crank and the crank shaft is more stable, so as to withstand large and frequent external impact forces, solve the problem that the crank will fall off or shake, and overcome the shortcomings of the background technology. The following technical solutions are adopted:

[0006] The locking structure of a bicycle crank is used to lock the crank on the crank shaft of a bicycle, characterized in that the locking structure comprises: a connecting sleeve, which cooperates with the crank shaft sleeve to pre-position the crank on the crank shaft; the inner peripheral wall portion of the connecting sleeve extends axially and obliquely to form a section of inclined wall, the inclined wall extends to the opening of the connecting sleeve, and the inner peripheral wall forms a locking space relative to the locking head of the crank shaft; the locking sleeve has an outer peripheral wall inclined axially; the locking sleeve is displaced axially along the crank shaft, enters the locking space and is locked and connected with the locking head, and the outer peripheral wall of the locking sleeve acts on the inclined wall and applies axial and radial forces to it, driving the inclined wall of the connecting sleeve to expand and deform in the radial direction and expand and cooperate with the crank, so as to constrain the connecting sleeve on the crank shaft and complete the locking of the crank and the crank shaft.

[0007] Preferably, when the outer peripheral wall of the locking sleeve acts on the inclined wall of the connecting sleeve, the outer peripheral wall fits and covers a portion of the inclined wall and forms an inclined fit with the inclined wall.

[0008] Preferably, the inner circumferential wall of the connecting sleeve is provided with a stop portion protruding toward its central axis and cooperating with the crank shaft sleeve, and the stop portion is located at the other opening of the connecting sleeve; when the outer circumferential wall of the locking sleeve acts on the inclined wall of the connecting sleeve, the locking sleeve and the stop portion are always in a non-contact state.

[0009] Preferably, when the inclined wall of the connecting sleeve expands and deforms in the radial direction to fit tightly with the crank, the other open portion of the connecting sleeve is subjected to a reaction force and shrinks and deforms toward its central axis, so that the stop portion is fastened to the crank center axis.

[0010] Preferably, there is a gap space between the locking sleeve and the stop portion, which is axially arranged side by side with the locking space. The gap space keeps the locking sleeve and the stop portion in a non-contact state at all times, and allows the locking sleeve to enter the locking space along the axial displacement of the crank center axis. After applying a force to the inclined wall of the connecting sleeve, the axial displacement can continue through the gap space, so as to apply a force to the inclined wall for a second time, thereby increasing the expanded diameter of the connecting sleeve.

[0011] Preferably, the outer circumference of the connecting sleeve is provided with a circle of flanges adapted to the mounting hole of the crank, and when the connecting sleeve is matched with the crank shaft sleeve, the crank is constrained on the connecting sleeve by the flanges.

[0012] Preferably, the locking sleeve and the locking head lock have mutually matching threaded portions, and the two are locked and connected via the threaded portions.

[0013] Preferably, the inner circumference of the locking sleeve is provided with a plurality of intermittently arranged clamping blocks.

[0014] Preferably, the outer peripheral wall of the locking sleeve covers the inclined wall to a covering area that accounts for at least two thirds of the total area of ​​the inclined wall.

[0015] Preferably, the inclined wall of the connecting sleeve and the outer peripheral wall of the locking sleeve have the same inclination angle.

[0016] From the above description of the utility model, it can be seen that compared with the prior art, the utility model has the following beneficial effects:

[0017] (1) The technical solution of the utility model provides a locking structure of a bicycle crank, which has a simple structure, is easy to manufacture, easy to implement and has low cost. It can be easily installed and disassembled, and the structural firmness is improved by double constraints, so that the locking effect of the crank and the crank shaft is more stable, and the disadvantage of the crank falling off or shaking is solved. In the locking structure of the technical solution, after the locking sleeve is fixedly connected to the crank shaft, the locking sleeve will simultaneously apply axial and radial forces to the connecting sleeve, wherein the axial force will push the connecting sleeve toward the crank shaft to limit the position, and the radial force will cause the connecting sleeve to expand and deform and expand and fit with the crank, so that the locking sleeve, the connecting sleeve and the crank form a whole, and the whole resists external forces, and the ability to resist external forces is stronger, the structure is more solid, the locking effect of the crank is more stable, and it can also withstand greater external impact forces, so as to prevent the crank from falling off or shaking. There will be no worries during daily riding, and the later maintenance costs will be reduced, and the experience will be stronger.

[0018] (2) In the present technical solution, the radial force applied by the locking sleeve to the connecting sleeve will also apply a radial reaction force to the locking sleeve; therefore, when the connection between the locking sleeve and the crankshaft becomes loose and begins to move backward, the radial reaction force will limit the displacement of the locking sleeve, so that the locking sleeve and the crankshaft always remain connected, thus solving the problem that the threaded connection will inevitably loosen after long-term riding and extending the service life.

[0019] (3) In the present technical solution, the inclined wall on the inner circumferential wall of the locking sleeve and the outer circumferential wall of the connecting sleeve are both inclinedly arranged. When the locking sleeve abuts against the connecting sleeve along the axial direction, the outer circumferential wall of the connecting sleeve will fit and cover part of the inclined wall, and the two will form an inclined fit. Also, because the locking sleeve and the connecting sleeve are in an inclined fit, as the locking sleeve gradually moves axially, it applies an axial force to the connecting sleeve while also applying a radial force through the inclined surface, so that the connecting sleeve is not only constrained in the axial direction, but also directly expands in the radial direction to fit with the crank. By adopting the inclined fit structural design method, only the axial force needs to be applied to generate the radial force at the same time. The structure is simple and effective, and the processing is even easier.

[0020] (4) In the present technical solution, the traditional locking sleeve is broken by directly applying an axial force to the stop portion of the connecting sleeve to press it against the crank shaft for constraint. That is, the stop portion and the locking sleeve always need to be in contact with each other, otherwise the locking sleeve cannot transmit the axial constraint force to the connecting sleeve. However, in actual operation and use, it is found that: since the locking sleeve and the connecting sleeve always maintain axial contact, when the connecting sleeve shakes under the influence of external impact force, the impact force will be directly transmitted to the locking sleeve in contact with it in the axial direction, and the locking sleeve will be driven to move axially. As time goes by, the impact force will gradually reduce the axial constraint force, and the crank will shake or fall off. Therefore, in order to solve this drawback, the present technical solution directly breaks the traditional structural method that must be in contact with each other, and adopts a non-contact connection method on the contrary. When the outer peripheral wall of the locking sleeve applies axial force to the inclined wall of the connecting sleeve, the locking sleeve and the stop portion are always in a non-contact state, that is, there is always a gap space between the two, so that the external impact force transmitted to the connecting sleeve can no longer be directly transmitted to the locking sleeve in the axial direction, but the external impact force is directly transmitted to the inclined surface in the radial direction, and the impact force is dispersed through the large-area contact between the inclined surfaces, so that the overall ability to resist impact force is stronger and the structural firmness is more stable.

[0021] (5) In the present technical solution, the gap space also has a second function, which is to provide space for the locking sleeve to make the second displacement. After the locking sleeve is locked in and locked with the connecting sleeve after the first displacement, a torsional force is continued to be applied to fully exert the torque so that the locking sleeve can continue to move forward and be completely locked with the connecting sleeve. Otherwise, it is difficult to ensure that the locking sleeve and the connecting sleeve are completely locked, thereby avoiding the situation where the locking sleeve moves backward due to loosening in the later stage.

[0022] (6) In the present technical solution, when the connecting sleeve and the crank are expanded and fitted, the open end of the connecting sleeve is subjected to the reaction force and is deformed toward its central axis by shrinking its diameter, that is, one end of the connecting sleeve is tilted and deformed into an expanded diameter opening, and the other end is deformed into a reduced diameter opening. The connecting sleeve is more firmly fastened to the crank shaft through the reduced diameter structure, further improving the overall structural stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is a structural schematic diagram of a bicycle crank assembly in the prior art;

[0025] Figure 2 This is a schematic structural diagram of a bicycle crank assembly according to an embodiment of the utility model;

[0026] Figure 3 This is an overall exploded view of a bicycle crank assembly according to an embodiment of the utility model;

[0027] Figure 4 for Figure 3 A cross-sectional schematic diagram of

[0028] Figure 5 This is a schematic structural diagram of the locking connection between the connecting sleeve and the crank shaft in the embodiment of the utility model;

[0029] Figure 6 This is a structural schematic diagram of the locking sleeve entering the locking space in the embodiment of the utility model;

[0030] Figure 7 for Figure 6 A partial enlarged view of part C is shown.

[0031] The description of the accompanying drawings is as follows: 1. Connecting sleeve; 11. Inclined wall; 12 / 14. Open mouth; 13. Stop portion; 15. Protruding edge; 2. Locking sleeve; 21. Outer peripheral wall; 22. Block; A. Locking space; B. Gap space; 3. Crank; 4. Crank center axis; 41. Locking head; 5. Pressure plate. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are preferred embodiments of the utility model and should not be regarded as excluding other embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0033] In the claims, specification and the above-mentioned drawings of the utility model, unless otherwise clearly defined, the use of terms such as "first", "second" or "third" etc. is to distinguish different objects rather than to describe a specific order.

[0034] In the claims, specification and the above-mentioned drawings of the utility model, unless otherwise explicitly defined, directional words, such as the terms "center", "lateral", "longitudinal", "horizontal", "vertical", "top", "bottom", "inside", "outside", "up", "down", "front", "back", "left", "right", "clockwise", "counterclockwise", etc., indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the specific protection scope of the utility model.

[0035] In the claims, specification and the above drawings of the utility model, unless otherwise clearly defined, if the term "fixed connection" or "fixed connection" is used, it should be understood in a broad sense, that is, any connection method without a displacement relationship and relative rotation relationship between the two, that is to say, including non-detachable fixed connection, detachable fixed connection, integrated connection and fixed connection through other devices or elements.

[0036] In the claims, specification and drawings of the present utility model, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0037] First embodiment

[0038] This embodiment provides a locking structure for a bicycle crank, which can not only constrain the crank 3 axially, but also constrain it radially. The double constraint improves the structural firmness, makes the locking effect of the crank 3 and the crank shaft 4 more stable, and can withstand large and frequent external impact forces, and solves the problem that the crank 3 may fall off or shake. Figures 2 to 7 The locking structure is mainly used to lock the crank 3 on the crank shaft 4 of the bicycle. The structure includes: a connecting sleeve 1 and a locking sleeve 2, wherein:

[0039] See also Figure 3 and Figure 4

[0040] The connecting sleeve 1, the crank shaft 4 passes through the connecting sleeve 1 and is sleeved with it, so that the crank 3 is pre-positioned on the crank shaft 4; the left and right ends of the connecting sleeve 1 each have an opening, the opening 14 on the left side is close to the crank shaft 4, and the opening 12 on the right side is far away from the crank shaft 4, and there is a full circle of inner peripheral wall between the two openings, and the inner peripheral wall part is inclined and extended along the axial direction to form a section of inclined wall 11, and the inclined wall 11 extends to the opening 12 at the right end of the connecting sleeve 1, so that the opening 12 at the right end of the connecting sleeve 1 is in the form of an expanded opening, and the opening 14 at the left end is in the form of a reduced opening; and when the connecting sleeve 1 is sleeved with the crank shaft 4 and the crank 3 is pre-positioned, a locking space A is formed by the inner peripheral wall relative to the locking head 41 of the crank shaft 4;

[0041] The locking sleeve 2 has an outer peripheral wall 21 inclined along the axial direction. The inclination direction of the outer peripheral wall 21 is the same as the inclination direction of the inclined wall 11 of the connecting sleeve 1, and the inclination angles of the two are equal. The locking sleeve 2 is inclined by the outer peripheral wall 21 so that its two ends are also in the form of an expanded diameter opening and a reduced diameter opening, respectively.

[0042] See also Figure 5 and Figure 6

[0043] The locking sleeve 2 and the connecting sleeve 1 cooperate in the following way: the locking sleeve 2 is displaced axially along the crank shaft 4, enters the locking space A and is locked and connected with the locking head 41 of the crank shaft 4, and at the same time, the outer peripheral wall 21 of the locking sleeve 2 acts on the inclined wall 11 and applies axial and radial forces to it (the locking sleeve 2 and the expansion structure of the connecting sleeve 1 are offset, and as the locking sleeve 2 continues to displace axially, the locking sleeve 2 will also apply radial force to the connecting sleeve 1, so that the expansion structure of the connecting sleeve 1 is expanded), driving the inclined wall 11 of the connecting sleeve 1 to expand and deform in the radial direction and to expand and fit with the through hole of the crank 3, so as to constrain the connecting sleeve 1 on the crank shaft 4 and complete the locking of the crank 3 and the crank shaft 4.

[0044] In this embodiment, the inner periphery of the locking sleeve 2 and the locking head 41 of the crank shaft 4 have mutually adapted threaded portions, and the two are locked and connected through the threaded portions. In other embodiments, buckle connection, clamping connection, etc. can be used instead, and it is only necessary to ensure that the locking sleeve 2 can enter the locking space A along the axial direction and can be fixedly matched with the crank shaft 4.

[0045] In this embodiment, the inner circumferential wall of the connecting sleeve 1 is provided with a stopper 13 protruding toward the central axis thereof. When the connecting sleeve 1 is sleeved on the crank shaft 4, the stopper 13 is just sleeved on the outer circumference of the crank shaft 4. The stopper 13 is a convex block, which is provided at the other opening 14 of the connecting sleeve 1, that is, the opening 14 at the left end. There are a plurality of stoppers 13, which are respectively arranged around the inner circumference of the connecting sleeve 1 and at the adjacent side of the inclined wall 11, and are arranged adjacent to the inclined wall 11 (that is, the starting end of the inclined wall 11).

[0046] In this embodiment, when the outer peripheral wall 21 of the locking sleeve 2 acts on the inclined wall 11 of the connecting sleeve 1, the outer peripheral wall 21 fits and covers part of the inclined wall 11 (as the locking sleeve 2 continues to move axially, the fitting coverage area becomes larger, but the covering area of ​​the inclined wall 11 at least accounts for two-thirds of the total area of ​​the inclined wall 11), and forms an inclined fit with the inclined wall 11, and at the same time applies axial and radial forces to the connecting sleeve 1, wherein the axial force: drives the stop portion 13 of the connecting sleeve 1 to be held against the upper limit constraint of the crank center axis 4 through the inclined surface; the radial force: causes the opening 12 at the right end of the connecting sleeve 1 to expand and deform to fit tightly with the crank 3, so that the locking sleeve 2, the connecting sleeve 1 and the crank 3 form a whole, and resist the external force through the whole, thereby improving the ability to resist external forces.

[0047] In this embodiment, since the locking sleeve 2 and the connecting sleeve 1 adopt the method of bevel matching, and the inclinations of the bevels of the two are equal, when the locking sleeve 2 enters the locking space A and makes the outer peripheral wall 21 act on the inclined wall 11 of the connecting sleeve 1, that is, when the bevels of the two are in contact, the locking sleeve 2 corresponds to the stop portion 13, and there is always a gap space B axially arranged side by side with the locking space A between the two. The gap space B makes the locking sleeve 2 and the stop portion 13 of the connecting sleeve 1 always in a non-contact state, that is, the locking sleeve 2 and the connecting sleeve 1 have no contact with each other except that the bevels are in contact with each other.

[0048] In this embodiment, the conventional locking sleeve 2 is used to directly apply axial force to the stop portion 13 of the connecting sleeve 1 to press and hold it against the crank shaft 4 for restraint (see Figure 1 ), that is, the stop portion 13 and the locking sleeve 2 always need to be in contact with each other, otherwise the locking sleeve 2 cannot transmit the axial restraining force to the connecting sleeve 1. However, in actual operation and use, it is found that: because the locking sleeve 2 and the connecting sleeve 1 always maintain axial contact, when the connecting sleeve 1 shakes under the influence of external impact force, the impact force will be directly transmitted to the locking sleeve 2 in contact with it in the axial direction, and the locking sleeve 2 will be driven to move axially. As time goes by, the impact force will gradually reduce the axial restraining force, and the crank 3 will shake or fall off. Therefore, in this embodiment, in order to solve this drawback, the traditional structural method that must be in contact with each other is directly broken, and a non-contact connection method is adopted instead, see Figure 6 and Figure 7When the outer peripheral wall 21 of the locking sleeve 2 applies axial force to the inclined wall 11 of the connecting sleeve 1, the locking sleeve 2 and the stop portion 13 are always in a non-contact state, that is, there is always a gap space B between the two, so that the external impact force transmitted to the connecting sleeve 1 can no longer be directly transmitted to the locking sleeve 2 in the axial direction, but the external impact force is directly transmitted to the inclined surface in the radial direction, and the impact force is dispersed by the large-area contact between the inclined surfaces, so that the overall ability to resist the impact force is stronger and the structural firmness is more stable.

[0049] In this embodiment, the radial force applied by the locking sleeve 2 to the connecting sleeve 1 will also apply a radial reaction force to the locking sleeve 2; therefore, when the connection between the locking sleeve 2 and the crank shaft 4 becomes loose and begins to move backward on its own, the radial reaction force will limit the displacement of the locking sleeve 2, so that the locking sleeve 2 and the crank shaft 4 always remain connected.

[0050] In this embodiment, the gap space B also has a second function, which is to provide space for the locking sleeve 2 to make a second displacement. After the locking sleeve 2 is locked in and locked with the connecting sleeve 1 after the first displacement, a torsional force is continued to be applied to fully exert the torque so that the locking sleeve 2 continues to move forward and is completely locked with the connecting sleeve 1. Otherwise, it is difficult to ensure that the locking sleeve 2 is completely locked with the connecting sleeve 1, thereby preventing the locking sleeve 2 from moving backward due to loosening in the later stage. Therefore, when the locking sleeve 2 performs the first displacement: the locking sleeve 2 enters the locking space A and is locked with the locking head 41 of the crank shaft 4 and fits with the inclined surface of the connecting sleeve 1. At this time, the locking sleeve 2 applies axial force and radial force to the connecting sleeve 1 for the first time; during the second displacement, the locking sleeve 2 continues to move in the axial direction to the gap space B, and the locking sleeve 2 applies axial force and radial force to the connecting sleeve 1 for the second time. The axial and radial forces are increased, so that the expanded diameter of the connecting sleeve 1 becomes larger, and the expansion force applied by the connecting sleeve 1 to the crank 3 is increased, and the firmness of the cooperation between the two is further enhanced; it can be seen that the design method of the gap space B can ensure that the torsional force of the locking sleeve 2 relative to the connecting sleeve 1 is sufficient, otherwise it is difficult to ensure that the inclined surfaces of the two are not completely fitted with each other if they are only locked once.

[0051] In this embodiment, the outer circumference of the connecting sleeve 1 is provided with a circle of flanges 15 adapted to the mounting holes of the crank 3 . When the connecting sleeve 1 is fitted with the crank shaft 4 , the crank 3 is constrained on the connecting sleeve 1 by the flanges 15 .

[0052] In this embodiment, the inner circumference of the locking sleeve 2 is provided with a plurality of intermittently arranged blocks 22, which can be cooperated with by external special tools to drive the locking sleeve 2 to enter and exit the locking space A and be threadedly connected with the locking head 41 of the crank shaft 4.

[0053] The working principle and usage process of this example:

[0054] When assembling crank 3, Figure 3 and Figure 4 First, the crank 3 is mounted on the crank shaft 4; then, see Figure 5 , the connecting sleeve 1 is arranged in the through hole of the crank 3 and is installed with the crank shaft 4, so that the crank 3 is pre-positioned on the crank shaft 4 through the convex edge 15 on the outer periphery of the connecting sleeve 1 to prevent the crank 3 from falling off directly from the crank shaft 4; then, the locking sleeve 2 is arranged in the locking space A through an external special tool, and is threadedly connected with the locking head 41 of the crank shaft 4 until the outer peripheral wall 21 of the locking sleeve 2 abuts against the inclined wall 11 of the connecting sleeve 1 to form an inclined surface fit; finally, a secondary locking is performed, and the locking sleeve 2 is continued to be twisted to drive the locking sleeve 2 to continue to move in the axial direction into the gap space B until the threaded connection with the locking head 41 is completely locked. Therefore, in the present invention, after the locking sleeve 2 is fixedly connected to the crank shaft 4, the locking sleeve 2 will simultaneously apply axial and radial forces to the connecting sleeve 1, wherein the axial force will hold the connecting sleeve 1 toward the crank shaft 4 to limit the position, and the radial force will cause the connecting sleeve 1 to expand and deform in diameter and fit tightly with the crank 3, so that the locking sleeve 2, the connecting sleeve 1 and the crank 3 form a whole, which can resist external forces as a whole, has a stronger ability to resist external forces, a more solid structure, and a more stable locking effect of the crank 3. It can also withstand greater external impact forces, thereby preventing the crank 3 from falling off or shaking. There will be no worries during daily riding, and the later maintenance costs will be reduced, with a stronger sense of experience.

[0055] The description of the above specification and embodiments is used to explain the protection scope of the utility model, but does not constitute a limitation on the protection scope of the utility model. Through the enlightenment of the utility model or the above embodiments, ordinary technicians in this field can obtain modifications, equivalent replacements or other improvements to the embodiments of the utility model or part of the technical features thereof through logical analysis, reasoning or limited experiments, which should be included in the protection scope of the utility model.

Claims

1. A locking structure for a bicycle crank, which is used to lock the crank on the crank shaft of the bicycle, characterized in that: The locking structure comprises: A connecting sleeve, which cooperates with the crank shaft sleeve to pre-position the crank on the crank shaft; the inner peripheral wall portion of the connecting sleeve is inclined and extends along the axial direction to form an inclined wall, and the inclined wall extends to the opening of the connecting sleeve, and the inner peripheral wall forms a locking space relative to the locking head of the crank shaft; The locking sleeve has an axially inclined outer wall; the locking sleeve is displaced axially along the crank shaft, enters the locking space and is locked and connected with the locking head, and the outer wall of the locking sleeve acts on the inclined wall and applies axial and radial forces to it, driving the inclined wall of the connecting sleeve to expand and deform in the radial direction to fit tightly with the crank, so as to constrain the connecting sleeve on the crank shaft and complete the locking of the crank and the crank shaft.

2. A locking structure for a bicycle crank as claimed in claim 1, characterized in that: When the outer peripheral wall of the locking sleeve acts on the inclined wall of the connecting sleeve, the outer peripheral wall fits and covers a portion of the inclined wall and forms an inclined fit with the inclined wall.

3. A locking structure for a bicycle crank as claimed in claim 2, characterized in that: The inner circumferential wall of the connecting sleeve is provided with a stop portion protruding toward its central axis and cooperating with the crank shaft sleeve, and the stop portion is located at the other opening of the connecting sleeve; when the outer circumferential wall of the locking sleeve acts on the inclined wall of the connecting sleeve, the locking sleeve and the stop portion are always in a non-contact state.

4. A locking structure for a bicycle crank as claimed in claim 3, characterized in that: When the inclined wall of the connecting sleeve expands and deforms in the radial direction to fit tightly with the crank, the other open part of the connecting sleeve shrinks and deforms toward its central axis due to the reaction force, so that the stop portion is fastened to the crank center axis.

5. A locking structure for a bicycle crank as claimed in claim 4, characterized in that: There is a gap space between the locking sleeve and the stop portion, which is axially arranged side by side with the locking space. The gap space keeps the locking sleeve and the stop portion in a non-contact state at all times, and allows the locking sleeve to enter the locking space along the axial displacement of the crank center axis. After applying a force to the inclined wall of the connecting sleeve, the locking sleeve can continue to axially displace through the gap space, so as to apply a force to the inclined wall for a second time, thereby increasing the expanded diameter of the connecting sleeve.

6. The locking structure of a bicycle crank as claimed in claim 1, characterized in that: The outer circumference of the connecting sleeve is provided with a circle of convex edges adapted to the mounting hole of the crank. When the connecting sleeve is matched with the crank central shaft sleeve, the crank is constrained on the connecting sleeve through the convex edges.

7. The locking structure of a bicycle crank as claimed in claim 2, characterized in that: The locking sleeve and the locking head lock have mutually adapted threaded parts, and the two are locked and connected through the threaded parts.

8. The locking structure of a bicycle crank as claimed in claim 2, characterized in that: The inner circumference of the locking sleeve is provided with a plurality of intermittently arranged clamping blocks.

9. The locking structure of a bicycle crank as claimed in claim 2, characterized in that: The outer peripheral wall of the locking sleeve fits and covers the inclined wall, and the covering area accounts for at least two thirds of the total area of ​​the inclined wall.

10. The locking structure of a bicycle crank as claimed in claim 2, characterized in that: The inclined wall of the connecting sleeve and the outer peripheral wall of the locking sleeve have the same inclination angle.

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