Labor-saving crank for bicycle

Abstract

To provide a labor-saving crank for a bicycle capable of increasing the length of a moment arm in pedaling and achieving the labor-saving effect, by additionally lengthening an outer arm.SOLUTION: A labor-saving crank includes: a base arm located outside the chain ring and one end of which is coupled to the chain ring to rotate with the chain ring; a base sprocket fixed to the base arm and facing the chain ring; an outer sprocket rotatably connected to the other end of the base arm at an outer-shaft center; a transmission member rotatably connected to the base sprocket and the outer sprocket; and an outer arm one end of which is rotatably connected to the outer-shaft center to synchronously rotate with the outer sprocket and the other end of which is rotatably connected by a pedal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bicycle drive structure, and more particularly to an assembly structure with a crank. [Background technology]

[0002] Current bicycle drive is as shown in Figure 10, where the chain ring is rotatably connected to the vehicle frame via a shaft, and a pair of cranks are connected to the shaft and the chain ring in opposite directions, and the ends of the cranks are rotatably connected to the pedals. When pedaling a bicycle, both feet are placed on the pedals and the cranks, and the cranks rotate counterclockwise in a circular motion, rotating the chain ring on the circular track mentioned above, which rotates the chain ring, which rotates the chain, which rotates the rear toothed disc, and finally the rear wheel rotates to move the bicycle forward.

[0003] In the case of not wearing cycling shoes and fixing the pedals in a movable manner, when the crank described above rotates in a circular track, it is basically driven by a downward force, and when rotating backwards, it is not possible to effectively apply force when the pedal is in an elevated position. Therefore, one solution is to install a pedal fixing structure to improve operating efficiency. Summary of the Invention [Problem to be solved by the invention]

[0004] However, since ordinary shoes are worn on ordinary bicycles, pedals having a mounting structure cannot be selected. [Means for solving the problem]

[0005] The labor-saving crank for bicycles includes the following:

[0006] The base arm is located outside the chainring, and one end of the base arm is coupled to the chainring so that the base arm rotates together with the chainring.

[0007] A base sprocket is fixed to the base arm and faces toward the chainring.

[0008] An outer sprocket rotates about an outer shaft and is rotatably connected to the other end of the base arm.

[0009] A transmission member is rotationally connected to the base sprocket and the outer sprocket.

[0010] An outer arm has one end rotatably connected to the outer shaft and rotates synchronously with the outer sprocket, and the other end of the outer arm is rotatably connected by a pedal.

[0011] The outer arm is rotatably connected to the base arm portion and rotates with the chainring to define a circular base arm track. The pedal is rotatably connected to the outer arm portion and rotates with the base arm to define a circular outer arm track. The outer arm track is offset outwardly relative to the base arm track. Effect of the Invention

[0012] In the labor-saving crank for bicycles of the present invention, the aforementioned base arm has a length that is approximately the same as that of a known crank, and the outer arm has an additional length, so that the length of the moment arm is increased during pedaling, thereby achieving the effect of labor-saving. Furthermore, the track of the outer arm is offset outward in the direction of travel compared to the track of the base arm, so that the original top dead center position (where pedaling force cannot be transmitted relative to the vertical position) where pedaling force cannot be transmitted can be offset forward, resulting in a more effective transmission of force, and finally achieving labor-saving and a good pedaling track. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a side view of the present invention, showing the forward extension position of the crank. [Diagram 2] FIG. 4 is a diagram showing the operation of the base arm in the downward extension position of the present invention; [Diagram 3] FIG. 4 is a diagram showing the operation of the base arm in the rearward extended position according to the present invention; [Figure 4] FIG. 4 is an operation instruction diagram of the base arm of the present invention in an upward extension position. [Diagram 5] FIG. 6 is a diagram showing a base arm position operation simulation instruction diagram for the base arm positions shown in FIGS. [Figure 6] FIG. 13 is an upper angle indication view of the outer arm of the present invention relative to the base arm. [Figure 7] FIG. 7 is an enlarged view of a local portion of FIG. 6. [Figure 8] FIG. 2 is a diagram showing the base arm track and outer arm track of the present invention. [Figure 9] FIG. 2 is a simulation diagram showing a comparison between the labor-saving body frame of the present invention and a standard body frame. [Figure 10] FIG. 1 is a side view of a crank and a chain ring of a bicycle according to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (One embodiment) Shown in Figures 1 to 5 and 8 is a bicycle labor-saving crank 1, which includes:

[0015] The base arm 200 is located outside the chainring 10 and has one end connected to the chainring 10 so that the base arm 200 rotates together with the chainring 10 .

[0016] A base sprocket 300 is fixed to the base arm 200 and faces the chain ring 10 .

[0017] An outer sprocket 400 is rotatably connected to the other end of the base arm 200 by an outer shaft 410 .

[0018] A transmission member 500 is rotationally connected to the base sprocket 300 and the outer sprocket 400 .

[0019] One end of the outer arm 600 is rotatably connected to the outer shaft 410 and rotates synchronously with the outer sprocket 400 , and the other end of the outer arm 600 is rotatably connected to the pedal 610 .

[0020] The outer arm 600 is rotatably connected to the base arm 200 and rotates together with the chain ring 10 to form a circular base arm track T1. The pedal 610 is rotatably connected to the outer arm 600 and rotates together with the base arm 200 to form a circular outer arm track T2. The outer arm track T2 is offset outwardly in the travel direction relative to the base arm track T1.

[0021] The aforementioned base arm 200 has a length that is approximately the same as that of a currently known crank (for example, 170 mm), and the additionally attached outer arm 600 extends the length (by approximately 85 mm), which extends the length of the moment arm during pedaling (compared to a crank whose original length is only 170 mm, the total length of the present invention reaches 255 mm (the total axial length of the base arm and the outer arm), which means that the moment arm is increased by half of the original length, which translates into 50% labor savings). Furthermore, since the outer arm track T2 is offset outward in the direction of travel compared to the base arm track T1, the original top dead center position (where pedaling force cannot be transmitted downward relative to the vertical position) where pedaling force cannot be transmitted can be offset forward (forward here refers to the direction of travel of the bicycle, and is shown as the right direction in the diagram as an example), resulting in a more effective transmission of force, labor savings, and a good pedaling track.

[0022] It should be noted that the present invention configures a crank by assembling the base arm 200 and the outer arm 600, and in principle, a pair of cranks drives the chain ring 10 from opposite positions on a bicycle. However, in order to clearly determine the position of the components, i.e., the operating status, the diagram shows only a single crank, and does not show the bicycle's labor-saving crank 1 attached to the bicycle frame.

[0023] The axial size of the base arm 200 of the present invention is larger than that of the outer arm 600. In principle, the base arm 200 is almost the same size as that of the known crank, the main difference is the additional installation of the outer arm 600, and the position of the outer arm 600 changes continuously and cyclically during pedaling, so that the unnecessary rear extension state of the outer arm 600 can be shortened not only in the forward direction but also in the backward dead area.

[0024] Furthermore, the detailed characteristics and mutual operation of each component achieves the desired effect. In the labor-saving bicycle crank 1 of the present invention, the transmission member 500 is a chain or a gear. The transmission member 500 in this embodiment is a chain. The chain runs between the base sprocket 300 and the outer sprocket 400. The gear is selected as an bevel gear, which facilitates the direction change and power transmission. In the transmission member 500 of the present invention, the outer arm 600 effectively controls the rotation position of the base arm 200 through the operation of the base sprocket 300 and the outer sprocket 400, that is, the outer arm 600 accurately controls the aforementioned circular outer arm track T2 through the rotation of the base arm 200.

[0025] When the base arm 200 extends horizontally toward the direction of travel of the bicycle, the outer arm 600 extends in the same direction as the base arm 200, and as shown in Figures 1 and 6, both the base arm 200 and the outer arm 600 of the present invention show their full length in the horizontal state, which is the position of the longest moment arm of the present invention.

[0026] In addition to the above-mentioned base arm 200 extending horizontally in the direction of travel of the bicycle, and both the base arm 200 and the outer arm 600 being horizontal, there is another embodiment, as shown in Figures 6 and 7, when the base arm 200 is horizontal and extending in the direction of travel of the bicycle, the axial extension line L1 of the outer arm 600 is angled with respect to the horizontal extension line L2 of the base arm 200, so that the outer arm 600 forms an upward elevation angle with respect to the base arm 200. The above-mentioned arrangement allows the pedaling action to be performed more effectively. The above-mentioned angle is a 36° arrangement. The above-mentioned angle is a 18° arrangement, which is the best angle when implementing the present invention.

[0027] 8, the base arm track T1 and the outer arm track T2 both have the same diameter, and the base arm track T1 and the outer arm track T2 intersect twice. The shortest distance between the outer arm track T2 and the chain ring 10 is smaller than the shortest distance between the base arm track T1 and the chain ring 10.

[0028] As shown in FIG. 9, when the labor-saving bicycle crank 1 is applied to a bicycle-like body frame, the bicycle body frame (herein referred to as the labor-saving body frame 710) can be improved to correspond to the labor-saving bicycle crank 1, that is, the center of the main axle tube (commonly known as the bottom bracket) at the position where the crank is attached to the body frame needs to be moved back and down (the moving back and down mentioned here refers to the labor-saving body frame 710 which is improved compared to the standard body frame 720), A in the figure refers to the center when the chain ring is attached to the standard body frame 720, and B in the figure refers to the center when the chain ring 10 is attached to the labor-saving body frame 710. The length of the outer arm 600 (herein referred to as the length refers to the distance that the outer arm 600 rotates between the outer axle center 410 and the pedal 610) is Y, and the base arm 200 is horizontal and extends in the direction of travel of the bicycle. The elevation angle of the outer arm 600 and the base arm 200 is θ. Based on the above requirements, the retreat value of the center position of the main shaft pipe of the labor-saving body frame 710 is B=A-Ycosθ, and the lowering value of the center position of the main shaft pipe of the labor-saving body frame 710 is B=A-Ysinθ. [Explanation of symbols]

[0029] 1. Labor-saving bicycle crank 10 Chainring 200 Base Arm 300 base sprocket 400 outer sprocket 410 Outer axis center 500 Transmission Components 600 Outer Arm 610 Pedal 710 Labor-saving body frame 720 standard body frame T1 Base Arm Truck T2 Outer Arm Track L1 Axial extension line L2 horizontal extension line A Center of the chainring when installed on a standard frame B Center of chainring when attached to labor-saving frame

Claims

1. In the labor-saving crank of bicycles, a base arm located outside the chain ring, one end of the base arm being coupled to the chain ring and rotating together with the chain ring; a base sprocket fixed to the base arm and facing the chain ring direction; an outer sprocket that rotates about an outer shaft center and is rotatably connected to the other end of the base arm; a transmission member rotatably connected to the base sprocket and the outer sprocket; an outer arm, one end of which is rotatably connected to the outer shaft center and rotates synchronously with the outer sprocket, and the other end of which is rotatably connected to a pedal; Including, the outer arm is rotatably connected to the base arm portion and rotates with the chainring to define a circular base arm track, the pedal is rotatably connected to the outer arm portion and rotates with the base arm to define a circular outer arm track; 10. A labor-saving crank for a bicycle, wherein the outer arm track is offset outward in the direction of travel relative to the base arm track.

2. 2. The labor-saving crank for a bicycle according to claim 1, wherein the transmission member is a chain or a gear.

3. 2. The labor-saving crank for a bicycle according to claim 1, wherein when said base arm extends horizontally in the direction of travel of the bicycle, said outer arm extends in the same direction as said base arm.

4. 2. The labor-saving crank for a bicycle as claimed in claim 1, wherein when the base arm extends horizontally in the direction of travel of the bicycle, the axial extension line of the outer arm is angled with the horizontal extension line of the base arm, and the outer arm and the base arm form an upward elevation angle.

5. 5. The labor-saving crank for a bicycle according to claim 4, wherein said angle is 36 degrees.

6. 5. The labor-saving crank for a bicycle according to claim 4, wherein said angle is 18 degrees.

7. 2. The labor-saving crank for a bicycle as claimed in claim 1, wherein both said base arm track and said outer arm track have the same diameter, and said base arm track and said outer arm track intersect twice.

8. 2. The labor-saving crank for a bicycle according to claim 1, wherein a minimum distance of said outer arm track to said chainring is less than a minimum distance of said base arm track to said chainring.

9. 2. The labor-saving crank for a bicycle according to claim 1, wherein the axial size of the base arm is greater than the axial size of the outer arm.

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