Retractable/extendable crank using a cylindrical cam, an end cam, or a swash plate cam, and bicycle using the same

Abstract

The present invention relates to a mechanical element, and more particularly, to a crank connected to a bicycle pedal or a handle for rotating a rotary body and to a bicycle using the same. The present invention uses a cylindrical cam, an end cam, or a swash plate cam, and the shafts of these cams and a shaft of a pedal or a handle for applying force are equipped with a miter gear (a bevel gear the number of teeth of which is 1:1 and the shaft angle of which is 90 degrees), such that the crank retracts / extends one time per one rotation of the pedal or the handle. The retractable / extendable crank of the present invention is advantageous in that the length of the crank is elongated to generate a large amount of rotating force in a force-applying section, and shortened in a section where no force is applied to reduce the actuating space occupied by the crank and apply a large amount of torque to the rotary body from the same force, without deviating from the normal motion range of the arms or legs during rotation. The retractable / extendable crank of the present invention has a significantly rigid structure and provides reliable operation, and thus is suitable as a driving crank to beconnected to a pedal of a bicycle. As compared with conventional bicycles, the bicycle using the crank of the present invention is supplied with a larger amount of rotating force in proportion to theelongation of the crank from the same force, thus enabling the bicycle of the present invention to travel quickly with less force and climb a steep upward slope in an easy manner.

Description

technical field [0001] The present invention relates to a mechanical part, and more particularly, to a crank connected to a bicycle pedal or a handle for rotating a rotating body, and a bicycle using the crank. Background technique [0002] One end of the crank that rotates the rotating body is fixed to the shaft of the rotating body, and the other end is connected to a unit that applies force to the handle, pedal, etc. The torque T to turn the rotating body is the value of the length (corresponding to the arm length) L of the crank multiplied by the force applied at the end of the crank. It is expressed in a mathematical formula as follows. [0003] T=F×L, here, F: force, L: arm length [0004] It can be seen from the mathematical formula that when the length of the arm is lengthened, that is, the length of the crank is lengthened, a greater torque can be obtained with the same force. When applied to a bicycle, the bicycle becomes faster and climbs steep grades more easi...

AI Technical Summary

Problems solved by technology

The variable-length crank rotation mechanism disclosed in this patent is not only complicated, but also has a large number of components, so the manufacturing cost is very high, and it is difficult to install on existing bicycles

[0009] In addition, a bicycle with a transmission that obtains a larger torque uses multiple gears, so that it is easy to climb a hill; at this time, although the torque is increased, it is easy to climb a hill, but in order to obtain a larger torque, it must be changed to a low speed, so speed will inevitably decrease

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