JP2010208582A - Crank mechanism of bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bicycle having a crank which applies a reduced load on knee joints of a pedaler by reducing the longitudinal movement of the path of a pedal. <P>SOLUTION: In this crank mechanism, an intermediate rotating shaft (3) in parallel with a crankshaft (1) is provided to the end of a first crank arm (2) engaged with the crankshaft, a second arm (4) longer than the first crank arm (2) is engaged with the intermediate rotating shaft so as to be rotated normally and reversely, a pedal (5) is provided to the end of the second arm (4), and a projection (7) is formed by extending the shaft of the pedal (5) to the inside of the bicycle and inserted into the slit of a guide member (6) which is affixed to a vehicle body. The crank mechanism is configured so as to be driven along the path of the pedal which is guided by the slit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an improvement in a bicycle crank mechanism.

As a conventional crank mechanism, an intermediate rotating shaft parallel to the crankshaft is provided at the end of the first crank arm, and the second arm is engaged with the intermediate rotating shaft so as not to rotate in the forward rotation direction. Japanese Patent Application Laid-Open No. 2007-55332 has a pedal provided at the end of the arm.
Japanese Patent Laid-Open No. 2003-312581 discloses a crank mechanism in which a crank radius is automatically expanded and contracted according to a load state by a link mechanism.

JP2007-55332A JP2003-312581A

However, in the conventional structure, there is an effect of reducing the force of the foot, but as the swing angle increases due to the pedal trajectory becoming larger than the longitudinal movement width of the first crank arm rotation trajectory, the knee joint There is a drawback that the burden becomes large.

An intermediate rotary shaft parallel to the crankshaft is provided at the end of the first crank arm engaged with the crankshaft, and a second arm longer than the first crank arm is engaged with the intermediate rotary shaft so as to be able to rotate forward and backward. By providing a pedal at the end of the second arm, the degree of freedom of the pedal track is increased and the movement width of the crank pedal in the front-rear direction can be reduced.

By adopting the above mechanism, the change in the angle of the knee is reduced, and the burden on the knee joint can be reduced.

It is the figure which looked at the crank mechanism of this invention from the side. It is the example which provided guidance in the locus | trajectory of the pedal of this invention. In the present invention, the second arm (4) is a folding type. In the present invention, the pedal is a rotary storage type.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of the crank mechanism of the present invention.
The first crank arm (2) is engaged with the crankshaft (1), and an intermediate rotation shaft (3) parallel to the crankshaft (1) is provided at the end of the first crank arm (2). A second arm (4) is engaged with the rotating shaft (3) so as to be rotatable forward and backward, and a pedal (5) is provided at the end of the second arm (4).

The second arm (4) can freely rotate forward and backward around the intermediate rotation axis (3), and can freely traverse the trajectory of the pedal (5) within a range where the second arm (4) can swing by a saw. Yes, that is, it is possible to paddle in an orbit like A, for example. The longer the length of the second arm (4) relative to the first crank arm (2), the greater the degree of freedom of the trajectory, and it is preferable that at least the length ratio is 1 or more.

FIG. 2 shows an example in which a guide is provided on the track of the pedal of the present invention.
A protrusion (7) is provided by extending the pedal (5) shaft to the inside of the bicycle, and this protrusion (7) is inserted into a slit of a guide member (6) fixed to the vehicle body (not shown). The crank can be driven by the pedal (5) track guided by the slit regardless of the hand.

FIG. 3 shows an example in which the second arm (4) is foldable in the present invention.
The second arm (4) is reversibly engaged in the B direction by a pin (8), and can be easily folded to be compact when storing the bicycle. On the other hand, during use, the second arm (4) always faces downward regardless of the rotational position of the first crank arm (2), and the pedal force also works downward. (4) does not fall in the B direction which is the folding direction.

FIG. 4 shows an example in which the pedal (5) is a rotary storage type in the present invention.
The pedal (5) is rotatably engaged about the longitudinal axis of the second arm (4), and can be easily rotated and stored when not in use. On the other hand, when in use, the second arm (4) always faces downward regardless of the rotational position of the first crank arm (2), and the pedaling force also works downward. There is no rotation around the longitudinal axis of the second arm (4).

The present invention is applicable to all bicycles in the form of a crank mechanism that is driven by human power.

1 Crankshaft 2 First Crank Arm 3 Intermediate Rotating Shaft 4 Second Arm 5 Pedal 6 Guide Member 7 Projection 8 Pin

Claims (1)

An intermediate rotary shaft parallel to the crankshaft is provided at the end of the first crank arm engaged with the crankshaft, and a second arm longer than the first crank arm is engaged with the intermediate rotary shaft so as to be able to rotate forward and backward. A crank mechanism provided with a pedal at the end of the second arm.

Images