JPH0789476A - Driving device for bicycle - Google Patents

Abstract

PURPOSE:To provide a driving device for a bicycle, by which very large rotating torque can be obtained by small stepping force. CONSTITUTION:The front end of an oscillating lever 29 which is provided near the axle 25 of a rear wheel 23 and is pivoted on a support shaft 27 is installed on a pedal shaft 21 in such a manner as to freely rotate. The rear end of the oscillating lever 29 is installed on a rack 31 in such a manner as to freely rotate, so that the rack 31 is moved up and down along a vertical movement guide 39 by the oscillation of the oscillating lever 29. A driving pinion 41 is rotatably fitted to the axle 25 in such a manner as to mesh with the rack 31, and the driving pinion 41 is connected to a rear wheel hub through a ratchet mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for running a bicycle.

[0002]

2. Description of the Related Art Generally, in a bicycle, a pedal is stepped on by a bending motion of a leg to rotate a sprocket via a crank arm. The rotation of the sprocket is transmitted to the wheels via a chain etc. and the bicycle runs, but in order to have excellent running performance, it is necessary to be able to obtain a large turning torque with a small stepping force. Is.

[0003]

In order to obtain a large turning torque with a small stepping force, the crank arm may be made long, but if it is made too long, the bending motion of the leg at the time of returning cannot be smoothly performed. hand,
On the contrary, the running performance is reduced, and the pedal may come into contact with the ground at the lower end position. Therefore, it is difficult to significantly reduce the stepping force in a bicycle using the drive device having such a configuration.

Therefore, an object of the present invention is to provide a bicycle drive device capable of obtaining an extremely large rotational torque with a small stepping force.

[0005]

To achieve this object, a bicycle drive apparatus of the present invention comprises a swing lever that swings around a rear wheel axle or near the rear wheel axle when a pedal is depressed, and a swing lever. And a driving force transmitting means provided at a rear end or a rear portion of the swing lever, the driving force transmitting means transmitting only the forward rotational force to the rear wheel when the rear end or the rear portion of the swing lever moves up and down. Is.

An extendable crank arm provided with a pedal, a driven portion provided on the crank arm, and an extendable guide for guiding the driven portion so that the crank arm is in an extended state only when the pedal is stepped on are provided. It is effective to configure the moving lever to swing with the rotation of the crank arm.

[0007]

The distance from the swing center of the swing lever, that is, the lever to the front end is much longer than the distance from the swing center to the rear end or the rear portion. The swing lever returns in a free state after applying a forward turning force to the rear wheels.

The extension of the crank arm increases the drive radius.

[0009]

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

FIG. 1 is a front view of a bicycle drive device according to the present invention, FIG. 2 is a plan view of a front portion of the bicycle drive device, and FIG. 3 is a plan view of a rear portion of the bicycle drive device.

Crank arm 3 having pedal 1 at the tip
As shown in detail in FIG. 4, is composed of a base portion 5 and an elastic portion 7 slidably inserted into the base portion 5,
A compression coil spring 9 that pushes the expandable portion 7 outward is arranged in the base portion 5.

Inside the crank arm 3, the frame 1
The expansion guide 13 supported by 1 is arranged, and a driven pin 17 (driven part) projecting from the expansion part 7 of the crank arm 3 is fitted into the guide groove 15 of the expansion guide 13. I'm out. As shown in detail in FIG. 5, the driven pin 17 has a roller 19 at the tip thereof.
Reference numeral 9 is a telescopic guide 13 according to the rotation of the crank arm 3.
It moves in the guide groove 15 of.

The guide groove 15 of the expansion / contraction guide 13 is formed in a semicircular shape on the return side A, but on the stepping side B, an elliptical shape (accurate to the right) in the front wheel direction (rightward in the figure). It does not have to be oval) and is formed to be drawn. Therefore, when the crank arm 3 rotationally moves to the step-in side B, the driven pin 17 moves the extension guide 13.
The guide arm 15 moves along the guide groove 15 while being pulled out to the outside, and as a result, the expandable portion 7 moves to the outside, and the crank arm 3 is in the extended state. Crank arm 3 is on the stepping side B
When it is in the horizontal state, it extends most (see phantom line C in FIG. 1), but when it is further rotated from the horizontal state, the guide groove 15
The expansion / contraction part 7 moves inward by the movement of the driven pin 17 along, and gradually contracts from the longest time. When the crank arm 3 reaches the return side A, the expansion / contraction part 7 is moved to the innermost side, and the crank arm 3 is in the contracted state (see the phantom line D in FIG. 1). After that, the crank arm 3 rotates in the contracted state until reaching the step-in side B.

The compression coil spring 9 arranged in the base portion 5 facilitates the outward movement of the contracting portion 7 on the step-in side B,
The reduction of the stepping force is promoted on the upper side of the stepping side B, which requires the largest stepping force.

A front end of a swing lever 29 that swings around a support shaft 27 provided near the axle 25 of the rear wheel 23 is rotatably attached to the pedal shaft 21, and the rear end of the swing lever 29 is attached. Is rotatably attached to the rack 31. The rocking lever 29 is composed of a central portion 33, and a front elastic portion 35 and a rear elastic portion 37 that are slidably inserted into the central portion 33 and rock according to the rotation of the crank arm 3. The rack 31 is vertically moved along a vertical movement guide 39 provided at the rear end of the frame 11.

It is preferable that a bearing is provided at the central portion 33 of the swing lever 29 so that the front stretchable portion 35 and the rear stretchable portion 37 slide smoothly.

A drive pinion 41 is rotatably fitted to the axle 25, and the drive pinion 41 meshes with the rack 31 to form a drive force transmission means. The drive pinion 41 is connected to the rear wheel hub 43 via a ratchet mechanism (not shown), and transmits the driving force (forward rotation force) to the rear wheel hub 43 only when rotating in the arrow X direction.

Therefore, when the swing lever 29 swings and the rack 31 rises as the crank arm 3 rotates,
The drive pinion 41 rotates in the direction of the arrow X and transmits the forward rotational force to the rear wheel 23. Since the drive pinion 41 is in a free state with respect to the lowering of the rack 31, the swing lever 29 smoothly swings and returns according to the rotation of the crank arm 3.

FIG. 6 is a front view showing a modification of the driving force transmitting means, and FIG. 7 is a plan view showing the modification.

A chain 47 is attached to the drive pinion 41 ', one end of which is attached to the rear end of the swing lever 29', and the other end of which is attached to an arm 45 fixed to the drive pinion 41 '. . When the swing lever 29 ′ swings and the rear end rises, the chain 47 pulls the drive pinion 41 ′ to rotate in the direction of the arrow X, transmitting the driving force to the rear wheel hub. When the rear end of the swing lever 29 ′ is lowered, the chain 47 is pulled by the tension coil spring 51 attached between the arm 45 and the attachment bar 49 fixed to the frame 11 to drive the pinion 4.
Return with 1 '.

Reference numeral 53 in the drawing denotes a chain stopper.

FIG. 8 is a diagram showing another modification of the driving force transmitting means.

The mounting bar 49 'is fixed to the swing center position of the swing lever 29' and has a driving pinion 41 ".
Has fewer teeth, and the chain 47 'attached to the rear of the arm 45' is of shorter construction.

[0024]

As described above, according to the bicycle drive device of the present invention, when the pedal is depressed to apply the stepping force to the front end of the rocking lever, it is provided at the rear end or the rear part of the rocking lever. It is possible to transmit an extremely large forward rotational force to the rear wheels via the drive force transmission means provided.

If the swing lever is swung in accordance with the rotation of the crank arm, which is in the extended state only when stepping on, the driving radius of the leg force when stepping on becomes longer, and a large forward turning force can be obtained with a smaller stepping force. You can Moreover,
Since the crank arm is in a contracted state when it is returned, the smooth bending motion of the leg is not interrupted and the pedal does not come into contact with the ground.

[Brief description of drawings]

FIG. 1 is a front view of a bicycle drive device according to the present invention.

FIG. 2 is a plan view of the front portion of the bicycle drive device.

FIG. 3 is a plan view of the rear portion of the bicycle drive device.

FIG. 4 is a diagram showing a crank arm in detail.

FIG. 5 is a diagram showing details of a driven pin portion.

FIG. 6 is a front view showing a modified example of driving force transmission means.

FIG. 7 is a plan view showing a modified example.

FIG. 8 is a front view showing another modification of the driving force transmitting means.

[Explanation of symbols]

1 pedal 3 crank arm 13 extension guide 17 driven pin (driven part) 23 rear wheel 25 axle 29, 29 'swing lever 31 rack (driving force transmission means) 41, 41', 41 '' driving pinion (driving force) Transmission means) 47, 47 'chain (driving force transmission means)

Claims (2)

[Claims] 1. A swing lever that swings about a rear wheel axle or the vicinity of the rear wheel axle when a pedal is depressed, and a driving force transmission means provided at a rear end or a rear portion of the swing lever. The driving force transmitting means transmits only the forward rotational force to the rear wheel when the rear end or the rear portion of the swing lever is moved up and down. 2. An extendable and retractable crank arm having a pedal, a driven portion provided on the crank arm, and an extension and contraction guide for guiding the driven portion so that the crank arm is in an extended state only when the pedal is stepped on. The drive device for a bicycle according to claim 1, wherein the swing lever swings with the rotation of the crank arm.