JPS593016Y2 - Bicycle gear/crank device - Google Patents

Description

[Detailed description of the invention] This invention is a gear crank device for a bicycle, specifically, a crank arm support part is provided at both ends of a crankshaft, a pair of crank arms are supported on these support parts, and the crank arm This invention relates to a bicycle gear/crank device comprising a change gear attached to one side of the bicycle.

Generally speaking, on competitive bicycles, depending on the athlete's leg strength,
The length from the center of the crankshaft to the center of the pedal shaft is changed, and even in the case of general bicycles, the length between the crankshaft and the pedal shaft is changed depending on the size of the bicycle.

However, in the conventional bicycle gear/crank device, the supporting part of the crank arm is provided so that its axis coincides with the rotational center position of the crankshaft, and therefore, as mentioned above, the rotational center of the crankshaft is located at a distance from the pedal axis center. In order to vary the length of the crank arm, it was necessary to prepare many types of crank arms with different lengths.

The present invention has been devised in view of the above points, and each support part of the crankshaft is displaced with respect to the rotation center of the crankshaft, and each of the crank arms is supported on each support part by freely changing the angle. By installing the crank arm at a different angle relative to the crankshaft support part, the effective length of the crank arm, that is, the length from the rotation center of the crankshaft to the center of the pedal shaft, can be adjusted as desired. By preparing a very small number of crank arms, it is possible to accommodate any required length.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gear crank device of the present invention will be explained below with reference to embodiments shown in the drawings.

In the figure, 1 is a crankshaft, which is mounted on a cylindrical bottom bracket 2 provided on the bicycle frame, between a ball holder 21 attached to the bracket 2 and a ball holder 22 fixed to the crankshaft 1, and a ball holder 23 attached to the bracket 2. and the crankshaft 1
Balls 25 and 26 are interposed between the ball pusher 24 and the screwed ball 24.
It supports free rotation through.

Crank arm support portions 5 are provided at both ends of the crankshaft 1.
, 5 are integrally formed in a protruding manner, and a pair of crank arms 6.6 each having a pedal (not shown) pivotally supported at the tip thereof are fitted into each of these supporting portions 5, 5, and each of the arms 6.6 is Each crank arm 6.6 is integrally supported by screwing a fixing bolt 7.7 into each support portion 5, 5 from the outside.

Therefore, in the present invention, in the above configuration, in order to make the respective support parts 5, 5 provided on the crankshaft 1 face each other, each axis A is displaced by a distance l with respect to the rotation center opening of the crankshaft 1, and , a plurality of concave and convex portions 8 extending in the axial direction are formed at equal intervals on the outer peripheral portion of each of the support portions 5, and the support portion A concavo-convex portion 9 having the same shape as the concave-convex portion 8 of No. 5 is formed, and by fitting these two concave-convex portions 8 and 9, each crank arm 6 is supported on each of the support portions 5 so as to freely change the angle. .

As a method for displacing the axis A of the support parts 5, 5 by one distance with respect to the rotation center opening of the crankshaft 1, the crankshaft 1 is arranged at the center of the bottom bracket 2 as shown in FIG. 1 fixed ball bearing 22 and a ball pusher 24 screwed onto the crankshaft 1 are formed concentrically with the crankshaft 1, in other words, with the bottom bracket 2, so that the axial center of the crankshaft 1 and the rotation center coincide with each other. , this crankshaft 1
Alternatively, as shown in FIG. 6, the crankshaft 1 may be disposed at a distance relative to the center of the bottom bracket 2 relative to the displacement amount l, and the crankshaft 1 may be disposed as shown in FIG. The ball bearing 22 and the ball pusher 24 are made eccentric with respect to the bottom bracket 2, and the shaft stop of the crankshaft 1 is displaced with respect to the rotation center, and the --shaped support portion 5 is provided concentrically with the axis of the crankshaft 1. , the other support portion 5 may be displaced by a distance of 21 with respect to the axis of the crankshaft 1, that is, by a distance of l with respect to the rotation center opening of the crankshaft 1.

Therefore, the angle of the crank arm 6 to each of the support parts 5 can be changed by changing the fitting position of the uneven parts 8 and 9, and can be done depending on the number of the uneven parts 8 and 9. The number of changes made is obtained.

As shown in FIG. 2, when the crank arm 6 is supported in the downward direction in FIG. The length Ll from the rotation center opening of the shaft 1 to the middle 68 of the pedal shaft of the pedal supported on the crank arm 6 is maximum.

Further, as shown in FIG. 3, when the crank arm 6 is supported in the extending direction of a straight line passing from the axis A of the support portion 5 to the rotation center opening of the crankshaft 1, that is, in the upward direction in FIG. The length Ll between the rotation center opening and the middle 68 of the pedal shaft is the minimum.

In other words, this length Ll is calculated from the maximum length Ll to the axis 4.
The dimension is shorter by 21, that is, twice the eccentricity l between 90 and 90.

Furthermore, by arbitrarily changing the mounting angle of the crank arm 6 with respect to the straight line passing through each axis 190, the length between the rotation center opening of the crankshaft 1 and the middle 68 of the pedal axis, that is, the effective length of the crank arm 6. The length could be adjusted in multiple stages.

Further, the axially side end of the crankshaft 1 is provided with a plurality of uneven parts extending in the axial direction on the outer periphery to form a chain gear mounting part 10 that is concentric with the rotation center opening of the crankshaft 1. An adapter 11 is fitted into the portion 10 and fixed by tightening the crank arm 6 with the bolt 7, and a chain gear 12 is attached to the tip of the adapter 11.

By the way, the Cheno gear 12 may be attached to the inner end side of the crank arm support portion 5 of the crankshaft 1 described above using the crank arm support portion 5.

In this case, as shown in FIG. 5, as the crank arm 6 rotates, the axis A of the support part 5 draws a circular locus 2 around the rotation center opening of the crankshaft 1, and at the same time A Cheno gear 12 attached to the support part 5 rotates around the circular locus 2, and the outer peripheral teeth of the gear 12 draw a circular locus H with a larger diameter than the gear 12. The chino 13 to be rotated will revolve on the circular locus H, thereby obtaining a circular locus H of the chino 13 that is larger than the diameter of the gear 12.
This increases the traction force of the bicycle, thereby increasing the speed of the bicycle.

As explained above, the gear/crank device of the present invention has the following features:
Since each support part of the crankshaft is displaced with respect to the rotation center of the crankshaft, and the crank arm is supported by each support part in a manner that allows the angle to be changed freely, the angle of the crank arm relative to the support part of the crankshaft can be changed. By installing the crank arm in this way, the effective length of the crank arm, that is, the length from the center of rotation of the crankshaft to the center of the pedal shaft, can be adjusted as desired.Therefore, unlike in the past, it is necessary to prepare many types of crank arms. By preparing only a small number of crank arms, it is possible to deal with any situation, and it is very convenient to manage and handle the crank arms.

In addition, in the present invention, by attaching the change gear to the crank arm support portion provided so as to be displaced from the crankshaft, as described above, a large speed increasing effect can be obtained compared to the diameter of the change gear.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing an example of the gear/crank device of the present invention, Figs. 2 and 3 are explanatory views of the crank arm attached to the support part of the crankshaft, and Fig. 4 is the crankshaft. Figure 5 is an explanatory diagram of another embodiment, Figure 6 is a right side view of the
This figure is a partially cutaway front view of another embodiment corresponding to FIG. 1. 1...Crankshaft, 5...Crank arm support part, 6...Crank arm, 10...
...Change gear mounting part, 22...Change gear, A...Support axis center, Mouth...Crankshaft rotation center, C...Pedal shaft center.

Claims (3)

[Scope of utility model registration request] (1) A bicycle gear crank device comprising crank arm support parts provided at both ends of a crankshaft, a pair of crank arms supported by these support parts, and a change gear attached to one side of the crank arm. A bicycle gear/crank device, characterized in that the supporting parts of the crankshaft are respectively displaced relative to the center of rotation of the crankshaft, and the crank arm is supported by each of the supporting parts so as to freely change the angle. (2) A change gear attachment part is provided on one axial end of the crankshaft and is concentric with the axis of the crankshaft, and the change gear is attached to the attachment part.Claim 1 of the Utility Model Registration Claims The gear/crank device for the bicycle described. (3) A bicycle gear according to claim 1, characterized in that a change gear attachment part is provided on a support part provided on one end of the crankshaft in the axial direction, and the change gear is attached to the attachment part.・Crank device.