Crank mechanism with length-adjustable force arm
The adjustable lever arm crank mechanism with eccentric structure and threaded connection design solves the problem of fixed length of bicycle crank lever arm, realizes simple and quick adjustment, and improves riding comfort and efficiency.
Patent Information
- Application Number
- CN202422826452.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-10-14
- Estimated Expiration
- 2034-11-19
AI Technical Summary
The length of the lever arm of existing bicycle cranks is fixed and cannot be flexibly adjusted according to the rider's leg length, height and pedaling habits, resulting in a poor riding experience, especially increasing the burden on the knee joints for people with short legs or limiting the power output of people with long legs.
A crank mechanism with adjustable lever arm length is designed. By changing the relative positions of the eccentric structure and the center hole, combined with the threaded connection and limit slot design, simple and quick lever arm length adjustment can be achieved to adapt to different riding needs.
It improves the convenience of adjusting the arm length and riding comfort, adapts to different riding scenarios, reduces the rider's energy loss and risk of injury in different environments, and improves riding efficiency and safety.
Smart Images
Figure CN223432422U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of bicycle accessories, in particular to a crank mechanism with adjustable lever arm length. Background Art
[0002] With the world's increasing attention to environmental issues and traffic congestion caused by vehicles and other modes of transportation, bicycles, as zero-emission short-distance commuting vehicles, have played an important role in reducing urban pollution and avoiding traffic jams.
[0003] Among the many components of a bicycle, the cranks connect between the center axle and the pedals. When the rider pedals, the cranks rotate along with the center axle, driving the bicycle. Therefore, the cranks transmit power to the bicycle's system. Since riders pedal to rotate the cranks, and leg length, height, and pedaling habits vary, ensuring the proper distance (the moment arm) between the pedals and the center axle is crucial to the rider's riding experience. An excessively long moment arm can increase knee strain for riders with shorter legs, while an excessively short moment arm can limit the power output of riders with longer legs. Currently, most bicycle cranks on the market use standard sizes, so riders can only adjust their riding trajectory by adjusting seat height or switching to different-sized cranks. Changing the cranks is complex and costly. Adjusting seat height essentially only adjusts leg angle and does not change the actual length of the moment arm on the cranks.
[0004] Therefore, it is necessary to provide a crank mechanism with adjustable lever arm length that can adjust the lever arm length and effectively improve the adjustment convenience. Utility Model Content
[0005] The purpose of the utility model is to provide a crank mechanism with adjustable lever arm length, which can adjust the lever arm length and effectively improve the adjustment convenience.
[0006] According to one aspect of the present invention, a crank mechanism with adjustable lever arm length is provided for connecting a pedal member on a bicycle, the crank mechanism comprising:
[0007] The handle body has a limiting groove formed at one end;
[0008] An eccentric structure is embedded and connected with the limiting groove, and the eccentric structure is provided with a center hole;
[0009] An axial hole is formed at the other end of the handle body, and a force arm is formed between the axial hole and the center hole;
[0010] When viewed in a direction parallel to the axis of the center hole, the center hole is located on the line connecting the center axis of the eccentric structure and the center axis of the shaft hole. When rotated by an angle R around the center axis of the eccentric structure, the center hole is located on the end of the eccentric structure close to the shaft hole or the end away from the shaft hole.
[0011] More preferably, the angle R satisfies the relationship: R=180°.
[0012] More preferably, the treading member is fixedly connected to the eccentric structure and is located on a side of the limiting groove away from the eccentric structure. The treading member is provided with a fixing rod, which passes through the limiting groove and is fixed to the center hole.
[0013] More preferably, the center hole is provided with threads, and the fixing rod is also provided with threads, and the fixing rod is screwed into the center hole, and the fixing rod is fixed to the center hole by threads.
[0014] More preferably, the tread member further comprises:
[0015] The pedal is fixedly connected to the fixing rod, and the pedal rotates along the axis of the fixing rod.
[0016] More preferably, if the center hole is located at one end of the eccentric structure close to the axial hole, the distance between the center hole and the axial hole is recorded as L1; if the center hole is located at one end of the eccentric structure away from the axial hole, the distance between the center hole and the axial hole is recorded as L2, and the distance L1 and the distance L2 satisfy the relationship: L1<L2.
[0017] More preferably, the distance L1 and the distance L2 further satisfy the relationship: L1 = 160 mm, and L2 = 170 mm.
[0018] More preferably, the eccentric structure is further integrally formed with a first protrusion and a second protrusion. When viewed in a direction parallel to the axis of the eccentric structure, the first protrusion is located on a side close to the center hole, and the second protrusion is located on a side of the center hole away from the first protrusion.
[0019] More preferably, the limiting groove is further integrally formed with a groove, and when viewed along the direction parallel to the axial hole, the two grooves are respectively located on both sides of the limiting groove.
[0020] More preferably, the first protrusion and the second protrusion are respectively embedded in the two grooves, the center hole abuts against the limiting groove, and the eccentric structure is embedded in the limiting groove.
[0021] The utility model has the following beneficial effects:
[0022] The distance between the flower core hole and the shaft hole is changed by the flower core hole being located on the eccentric structure near one end of the shaft hole or away from the other end, so that the crank mechanism can adjust the length of the force arm, and the flower core hole rotates by an angle R around the central axis of the eccentric structure to adjust the two force arms, thereby effectively improving the convenience of adjusting the length of the force arm. BRIEF DESCRIPTION OF DRAWINGS
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.
[0024] Figure 1 A perspective structural schematic view of the crank mechanism connected with the treadle of the embodiment of the present application;
[0025] Figure 2 A perspective structural exploded schematic view of the crank mechanism and the treadle of the embodiment of the present application;
[0026] Figure 3 A plane structural schematic view of the crank mechanism of the embodiment of the present application;
[0027] Figure 4 A plane structural schematic view of the back of the crank mechanism of the embodiment of the present application;
[0028] Figure 5 A position change schematic view of the flower core hole on the eccentric structure of the crank mechanism of the embodiment of the present application;
[0029] Figure 6 A perspective structural schematic view of the eccentric structure of the crank mechanism of the embodiment of the present application;
[0030] Figure 7 A perspective structural schematic view of the treadle of the embodiment of the present application;
[0031] Figure 8 A plane structural isometric view of the back of the crank mechanism of the embodiment of the present application;
[0032] BRIEF DESCRIPTION OF DRAWINGS: 100, crank mechanism; 10, handle body; 11, limiting groove; 11A, groove; 20, eccentric structure; 21, flower core hole; 22, first protrusion; 23, second protrusion; 30, shaft hole; 40, treadle; 41, fixed rod; 42, pedal; F1, first direction; F2, second direction; P1, connecting line. DETAILED DESCRIPTION
[0033] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be provided below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.
[0034] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.
[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are intended solely for the purpose of describing specific embodiments and are not intended to limit this invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0036] Please refer to Figures 1-8 In one embodiment of the present invention, a crank mechanism 100 with adjustable lever arm length is provided for connecting a pedal member 40 on a bicycle. The crank mechanism 100 includes a handle body 10 , an eccentric structure 20 and an axle hole 30 .
[0037] A limiting groove 11 is formed at one end of the handle body 10. The eccentric structure 20 is embedded and connected to the limiting groove 11, and the eccentric structure 20 is provided with a center hole 21. The axial hole 30 is formed at the other end of the handle body 10, and a force arm is formed between the axial hole 30 and the center hole 21. When viewed in a direction parallel to the axis of the center hole 21, the center hole 21 is located on the line P1 connecting the central axis of the eccentric structure 20 and the central axis of the axial hole 30. When rotated by an angle R around the central axis of the eccentric structure 20, the center hole 21 is located on the end of the eccentric structure 20 close to the axial hole 30 or the end away from the axial hole 30.
[0038] This design allows for adjustable lever arm length on bicycles. The key lies in adjusting the effective lever arm length of the crank by varying the relative position of the eccentric structure 20 and the center hole 21. A short lever arm is suitable for high-speed, flat-road riding. A shorter lever arm reduces pedaling distance and improves pedaling efficiency, making it ideal for situations requiring frequent acceleration or maintaining high speeds. A long lever arm is suitable for climbing or long-distance riding. A longer lever arm provides greater leverage, allowing the rider to output greater torque with less effort, especially when more power is required (such as when climbing). By allowing the center hole 21 to be positioned closer to or further from the axle hole 30, the rider can select the appropriate lever arm length based on their actual needs, improving riding comfort and efficiency. The design of the eccentric structure 20 allows the center hole 21 to rotate about the axis of the eccentric structure 20 in either the first direction F1 or the second direction F2, enabling a simple and quick adjustment mechanism. This structure is not only relatively simple and easy to manufacture and maintain, but also requires no replacement components; the lever arm length can be adjusted simply by rotating the eccentric structure 20, making operation convenient and efficient. The method of realizing two-speed adjustment on a straight line (line P1) also allows the force arm to change its length without changing the direction of force transmission.
[0039] More preferably, the angle R satisfies the relationship: R=180°.
[0040] When R = 180°, the center hole 21 can be rotated from one extreme position of the eccentric structure 20 (close to the shaft hole 30) along the first direction F1 or the second direction F2 to the other extreme position (away from the shaft hole 30). This design ensures that the change in the lever arm length between the two adjustments is the most significant, thereby maximizing the lever arm length difference. Setting the angle R = 180° allows full adjustment of the lever arm with a simple rotation operation. This design does not require complex multi-step adjustments. Simply rotate the eccentric structure 20 180° in a specific direction, and the center hole 21 will switch to another position, providing the maximum range of change.
[0041] More preferably, the treading member 40 is fixedly connected to the eccentric structure 20 and is located on the side of the limiting groove 11 away from the eccentric structure 20. The treading member 40 is provided with a fixing rod 41, and the fixing rod 41 passes through the limiting groove 11 and is fixed to the center hole.
[0042] Among them, the fixing rod 41 passes through the limiting groove 11 and is fixed to the center hole. This design can ensure the stability of the tread member 40 on the eccentric structure 20. The limiting groove 11 provides a force-guiding channel, and the fixing rod 41 ensures that the tread member 40 will not shake or slide during use, thereby improving the reliability and safety of force transmission. The abutment against the limiting groove 11 can accurately define the position of the fixing rod 41 to prevent it from unnecessary displacement. This design helps to ensure that the position of the tread member 40 is fixed after each adjustment, avoiding errors. The limiting groove 11 is designed as a support position for the fixing rod 41, which can withstand the reaction force generated by the tread member 40 during use. The fixing rod 41 is screwed into the center hole and abuts the limiting groove 11, ensuring that it is firmly locked after the adjustment is completed. This design means that after adjusting the length of the lever arm, the rider does not need to worry about loosening or displacement during riding, ensuring safety during riding.
[0043] More preferably, the center hole 21 is provided with threads, and the fixing rod 41 is also provided with threads, and the fixing rod 41 is screwed into the center hole 21 , and the fixing rod 41 is fixed to the center hole 21 by threads.
[0044] Among them, threaded fixing provides a stronger mechanical connection method. The friction generated by the thread during the screwing and locking process can ensure that the fixing rod 41 is firmly locked in the center hole 21 to prevent loosening or displacement. This design can cope with the vibration, impact and reaction force generated during bicycle riding, ensuring the stability of force transmission. Compared with other forms of fixation (such as clips or rivets), threaded connection has the characteristics of high strength and long-term stability, and is more suitable for maintaining a reliable connection under repeated use and adjustment. The threaded structure not only provides a firm fixation, but also facilitates adjustment and disassembly. By screwing in or out the fixing rod 41, the user can easily adjust the fixing position, rotate the eccentric structure 20 and change the length of the force arm or the position of the pedal 42. Compared with non-detachable fixing methods, threaded connection provides more flexible adjustment possibilities to meet different riding needs. Due to its structural strength and tight coupling characteristics, threaded connection can more effectively transmit the torque during pedaling, reduce energy loss, and ensure more efficient power transmission during cycling.
[0045] More preferably, the treading member 40 further includes a pedal 42 . The pedal 42 is connected to the fixing rod 41 and rotates around the axis of the fixing rod 41 .
[0046] Wherein, by designing the pedal 42 can rotate around the fixed rod 41 axis, pedal 42 can be adjusted with the natural movement of the rider's feet, reduce the fixed angle of the feet of the bondage. During the riding process, the angle of the foot will change, if the pedal 42 is fixed, may cause the foot to produce discomfort or fatigue. Rotatable pedal 42 design can relieve foot pressure, improve the comfort of riding. If the pedal 42 is completely fixed at an angle, long time riding may cause unnatural force on the joints such as ankle, knee, cause muscle fatigue or joint injury. Rotatable pedal 42 can be adjusted according to the dynamic angle of the foot during riding, in line with ergonomics, reduce the stress on the joints, reduce the burden of long time riding on the feet and legs, reduce the risk of injury. Rotatable pedal 42 design allows the rider to maintain the optimal foot posture in different pedaling angles and power transmission process. This can improve the pedaling efficiency and avoid the loss of power transmission due to the fixed angle of the pedal 42. When accelerating or climbing, the rider's foot often needs to be adjusted, such pedal 42 design can make the rider more effectively use the pedaling power, improve the overall riding performance. And each rider's pedaling habit and foot posture is different, rotatable pedal 42 design provides flexibility for different riders. Whether you prefer inside eight, outside eight, or are used to free rotation of the ankle, this design can adapt to individual riding habits and improve user experience.
[0047] More preferably, if the flower hole 21 is located on the eccentric structure 20 close to one end of the shaft hole 30, the distance between the flower hole 21 and the shaft hole 30 is recorded as L1, and if the flower hole 21 is located on the eccentric structure 20 away from one end of the shaft hole 30, the distance between the flower hole 21 and the shaft hole 30 is recorded as L2, the distance L1 and the distance L2 satisfy the relationship: L1 < L2.
[0048] Wherein, the force arm refers to the distance between the flower hole 21 (the connecting hole of the pedaling part 40) and the shaft hole 30 (the connecting hole of the crank and the middle shaft), which directly affects the power required for pedaling and the efficiency of riding. Through this design, the length of the force arm can be adjusted according to different needs, so that the bicycle can meet different riding scenes. Users can choose the appropriate length of the force arm according to their needs. L1 corresponds to a shorter force arm suitable for racing type riding, while L2 corresponds to a longer force arm suitable for strength type riding. This adjustable design allows riders to adjust the pedaling torque of the bicycle in different environments to meet various riding styles and needs. Through this setting, users can flexibly adjust the length of the force arm to balance efficiency and power during the riding process.
[0049] More preferably, the distance L1 and the distance L2 also satisfy the relationship: L1 = 160 mm, and L2 = 170 mm.
[0050] wherein 160mm and 170mm are common crank lengths that have been proven by practice and are in line with ergonomics. When riding, a crank length that is too long or too short will affect the pedaling efficiency and comfort of the rider. The height, leg length, and riding style of the rider all affect their preference for the crank length. Setting the adjustable range of 160mm and 170mm can cover the needs of more riders.
[0051] More preferably, the eccentric structure 20 is further integrally formed with a first protrusion 22 and a second protrusion 23, and the first protrusion 22 is located on one side close to the eyelet hole 21, and the second protrusion 23 is located on the side of the eyelet hole 21 away from the first protrusion 22, as viewed in the direction parallel to the axis of the eccentric structure 20.
[0052] The design of the first protrusion 22 and the second protrusion 23 can help fix the stability of the eccentric structure 20. The protrusions act as positioning elements, preventing the eccentric structure 20 from rotating or moving during use. The second protrusion 23 is located on the opposite side of the eyelet hole 21, providing symmetrical support for the eccentric structure 20. The first protrusion 22 is close to one side of the eyelet hole 21, and when adjusting the length of the force arm, the protrusion acts as a positioning element to prevent the position of the eyelet hole 21 from deviating from the designed range of force arm length. When installing or dismounting the eccentric structure 20, the protrusions can serve as positioning and guiding elements, making the installation process more intuitive and simple. The protrusions can serve as guides during installation, ensuring that the eccentric structure 20 can be correctly placed into the limiting groove 11, and also reducing the probability of incorrect installation. When adjustment or replacement is needed, the presence of the protrusions can provide reference points, allowing the rider or technician to quickly determine the correct position and improve work efficiency.
[0053] More preferably, the limiting groove 11 is further integrally formed with a recess 11A, and as viewed in the direction parallel to the axis hole 30, two recesses 11A are respectively located on both sides of the limiting groove 11.
[0054] The first protrusion 22 and the second protrusion 23 can ensure the precise positioning of the eccentric structure 20 in the limiting groove 11 through cooperation with the recess 11A. The recess 11A provides a precise guide track for the protrusions, ensuring that the movement trajectory of the protrusions in the recess 11A does not deviate, thereby keeping the entire structure stable and preventing loosening, misalignment, or inaccurate adjustment during use. The recess 11A allows the protrusions to be precisely embedded in the limiting groove 11, providing a fixed adjustment range. When adjusting the force arm, the cooperation between the protrusions and the recess 11A ensures the accuracy of the adjustment position, avoiding errors caused by improper adjustment.
[0055] More preferably, the first protrusion 22 and the second protrusion 23 are respectively embedded in the two grooves 11A, the center hole 21 abuts against the limiting groove 11 , and the eccentric structure 20 is embedded in the limiting groove 11 .
[0056] The design of first and second protrusions 22 and 23, which respectively fit into groove 11A, ensures the precise positioning of eccentric structure 20 within retaining groove 11, preventing displacement or misalignment under the action of force and improving structural stability. The close fit between the protrusions and groove 11A ensures that eccentric structure 20 is securely fixed in place during adjustment, preventing any undesirable loosening. The design of center hole 21 abutting retaining groove 11 further enhances the stability of the connection point and limits the relative movement of eccentric structure 20.
[0057] In this way, by locating the center hole 21 on the eccentric structure 20 at one end close to the shaft hole 30 or at the end away from the shaft hole 30, the distance between the center hole 21 and the shaft hole 30 is changed, so that the crank mechanism 100 can adjust the length of the lever arm, and the center hole 21 is rotated around the central axis of the eccentric structure 20 by an angle R to achieve the adjustment of the two lever arms, which effectively improves the convenience of adjusting the length of the lever arm.
[0058] The above-described embodiments merely represent several embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and all such modifications and improvements fall within the scope of protection of the present invention.
Claims
1. A crank mechanism with adjustable lever arm length, used for connecting a pedal member on a bicycle, characterized in that: The crank mechanism comprises: The handle body has a limiting groove formed at one end; An eccentric structure is embedded and connected with the limiting groove, and the eccentric structure is provided with a center hole; An axial hole is formed at the other end of the handle body, and a force arm is formed between the axial hole and the center hole; When viewed in a direction parallel to the axis of the center hole, the center hole is located on the line connecting the center axis of the eccentric structure and the center axis of the shaft hole. When rotated by an angle R around the center axis of the eccentric structure, the center hole is located on the end of the eccentric structure close to the shaft hole or the end away from the shaft hole.
2. A crank mechanism with adjustable lever arm length according to claim 1, characterized in that: The angle R satisfies the relationship: R=180°.
3. The crank mechanism with adjustable arm length according to claim 2, characterized in that: The treading member is fixedly connected to the eccentric structure and is located on a side of the limiting groove away from the eccentric structure. The treading member is provided with a fixing rod, which passes through the limiting groove and is fixed to the center hole.
4. The crank mechanism with adjustable lever arm length according to claim 3, characterized in that: The center hole of the flower is provided with a thread, and the fixing rod is also provided with a thread. The fixing rod is screwed into the center hole of the flower, and the fixing rod is fixed to the center hole of the flower with threads.
5. The crank mechanism with adjustable lever arm length according to claim 4, characterized in that: The tread member further comprises: The pedal is fixedly connected to the fixing rod, and the pedal rotates along the axis of the fixing rod.
6. The crank mechanism with adjustable lever arm length according to claim 4, characterized in that: If the center hole is located at one end of the eccentric structure close to the axial hole, the distance between the center hole and the axial hole is recorded as L1. If the center hole is located at one end of the eccentric structure away from the axial hole, the distance between the center hole and the axial hole is recorded as L2. The distance L1 and the distance L2 satisfy the relationship: L1<L2.
7. The crank mechanism with adjustable lever arm length according to claim 6, characterized in that: The distance L1 and the distance L2 also satisfy the relationship: L1 = 160 mm, and L2 = 170 mm.
8. The crank mechanism with adjustable lever arm length according to claim 1, characterized in that: The eccentric structure is also integrally formed with a first protrusion and a second protrusion. When viewed in a direction parallel to the axis of the eccentric structure, the first protrusion is located on a side close to the center hole, and the second protrusion is located on a side of the center hole away from the first protrusion.
9. The crank mechanism with adjustable lever arm length according to claim 8, characterized in that: The limiting groove is further integrally formed with a groove, and when viewed along the direction parallel to the axial hole, the two grooves are respectively located on both sides of the limiting groove.
10. The crank mechanism with adjustable lever arm length according to claim 9, characterized in that: The first protrusion and the second protrusion are respectively embedded in the two grooves, the center hole abuts against the limiting groove, and the eccentric structure is embedded in the limiting groove.