WO2001021473A1

WO2001021473A1 - Length varying device for pedal arms of bicycle

Info

Publication number: WO2001021473A1
Application number: PCT/KR2000/001053
Authority: WO
Inventors: Seok Gyun Lee
Priority date: 1999-09-21
Filing date: 2000-09-20
Publication date: 2001-03-29
Also published as: KR100357538B1; KR20000000141A

Abstract

Disclosed is a length varying device for the pedal arms of a bicycle which is capable of transmitting a maximum power to the rear wheel of the bicycle at a minimum energy. The length varying device includes a pair of pedal arm bodies constituting the pedal arms of a bicycle, respectively, each pedal arm body having a pedal mounted to one end of the pedal arm body, a roll bearing mounted to the other end of the pedal arm body, and a slitted hollow longitudinal portion serving to allow the pedal arm body to slide longitudinally with respect to the drive shaft while rotating, a pair of pedal arm guide members fixedly mounted to opposite ends of a drive shaft and adapted to guide the longitudinal sliding movement of the pedal arm bodies, respectively, each pedal arm guide member having roll bearings received in the hollow longitudinal portion of the associated pedal arm body and adapted to guide the longitudinal sliding movement of the associated pedal arm body, and a pair of guide rails each coming into contact with the roll bearing of the associated pedal arm body for at least a part of every rotation of the associated pedal arm body, thereby causing the pedal arm body to slide longitudinally with respect to the drive shaft, so that each of the pedal arm bodies has an effective length varying during the rotation thereof.

Description

LENGTH VARYING DEVICE FOR PEDAL ARMS OF BICYCLE

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a bicycle, and more particularly to a length varying device for the pedal arms of a bicycle which is capable of transmitting a maximum power to the rear wheel of the bicycle at a minimum energy.

Description of the Related Art

The drive power of a bicycle, which is widely used for movement or leisure purposes, is generated by a manual force applied to pedals respectively provided at pedal arms mounted at opposite sides of a drive sprocket to which a driven sprocket is connected via an endless chain. The drive power from the drive sprocket is transmitted to the rear wheel of the bicycle via the endless chain, thereby rotating both the front and rear wheels of the bicycle. In order to achieve an easy running of such a bicycle with a reduced energy, a gearing unit has been proposed which includes a plurality of gears mounted to the rear wheel of the bicycle and configured to be manually varied in gearing position to allow the bicycle to meet the running environment thereof. However, known bicycles have a problem in that a great manual power is consumed for a running on a slope or for a long distance because each pedal arm adapted to rotate a drive sprocket fixedly mounted to a drive shaft traversely arranged at a bicycle housing has a fixed length of about 17 cm, so that it rotates usually along a circle of a fixed diameter.

In order to solve the above mentioned problem, the inventor proposes, in the power transmission of a bicycle, an incorporation of a technique of a new concept for varying the length of pedal arms adapted to transmit a drive power to the rear wheel of the bicycle in order to allow the bicycle to run stably and smoothly with a reduced manual force.

SUMMARY OF THE INVENTION

Therefore, an object of the invention is to provide a length varying device for the pedal arms of a bicycle which is capable of freely varying the pedal arms during a 360 "rotation of those pedal arms about a drive shaft, thereby achieving a transmission of maximum power to the rear wheel of the bicycle using a reduced manual force.

In accordance with the present invention, this object is accomplished by providing a length varying device for pedal arms of a bicycle including a support frame, a drive shaft rotatably fitted in a housing integral with the support frame, and a drive sprocket fixedly mounted to the drive shaft, the pedal arms serving to transmit a manual drive force, applied thereto, to the drive shaft to generate a drive power for the drive sprocket, comprising: a pair of pedal arm bodies constituting the pedal arms of the bicycle, respectively, each of the pedal arm bodies having a pedal mounted to one end of the pedal arm body, a roll bearing mounted to the other end of the pedal arm body, and a hollow longitudinal portion extending longitudinally from a portion of the pedal arm body near the roll bearing toward the pedal by a desired length and having a longitudinal slit, the hollow longitudinal portion serving to allow the pedal arm body to slide longitudinally with respect to the drive shaft while rotating about a rotating axis corresponding to a center of the drive shaft; a pair of pedal arm guide members fixedly mounted, at opposite sides of the drive sprocket, to opposite ends of the drive shaft and adapted to guide the longitudinal sliding movement of the pedal arm bodies, respectively, each of the pedal arm guide members having roll bearings received in the hollow longitudinal portion of an associated one of the pedal arm bodies and adapted to guide the longitudinal sliding movement of the associated pedal arm body; and a pair of guide rails respectively mounted to the support frame in the vicinity of the pedal arm bodies, each of the guide rails coming into contact with the roll bearing provided at an associated one of the pedal arm bodies for at least a part of every rotation of the associated pedal arm body, thereby causing the pedal arm body to slide longitudinally with respect to the drive shaft, so that each of the pedal arm bodies has an effective length varying during the rotation thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which:

Fig. 1 is an exploded perspective view illustrating the whole configuration of a length varying device for the pedal arms of a bicycle in accordance with an embodiment of the present invention;

Fig. 2 is an exploded perspective view illustrating an essential part of the length varying device shown in Fig. 1;

Fig. 3 is a cross-sectional view illustrating an assembled configuration of the length varying device shown in Fig. 1; and Figs. 4a to 4d are views respectively illustrating successive operation states of the length varying device shown in Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 is an exploded perspective v ew illustrating the whole configuration of a length varying device for the pedal arms of a bicycle in accordance with an embodiment of the present invention.

As shown in Fig. 1, the length varying device of the present invention includes a pair of pedal arm guide members 10 respectively mounted, at opposite sides of a drive sprocket 4, to opposite ends of a drive shaft 1 rotatably fitted in a housing 5 integral with a support frame 2 of a bicycle by means of bearings 3, to which the length varying device of the present invention is applied. The length varying device also includes a pair of pedal arm bodies 20 constituting respective pedal arms of the bicycle. The pedal arm bodies 20 are coupled to the pedal arm guide members 10 in such a fashion that they are mounted at a variable length position thereof to opposite ends of the drive shaft 1 extending outwardly from the housing 5, respectively. Since the mounting position of each pedal arm body 20 to the drive shaft 1 is variable, the effective length of the associated pedal arm serving to generate a rotation of the drive shaft 1 is variable. The length varying device further includes a pair of guide rails 33 mounted in the vicinity of the pedal arm bodies 20 and adapted to vary respective mounting positions of the pedal arm bodies 20, thereby varying respective effective length of the pedal arms. One of the pedal arm guide members 10 is fixedly mounted to one end of the drive shaft 1, outwardly protruded from the housing 5, under the condition in which the drive sprocket 4 is interposed between the pedal arm guide member 10 and the end of the housing 5 facing the pedal arm guide member 10. The other pedal arm guide member 10 is fixedly mounted to the other end of the drive shaft 1 outwardly protruded from the housing 5. As best shown in Fig. 2, each pedal arm guide member 10 includes a guide member body 6, and a pair of two hollow fixed shafts 7 provided at a surface of the guide member body 6 facing the associated pedal arm body 20. The fixed shafts 7 extend toward the associated pedal arm body 20. A pair of roll bearings 8 each cladded at an outer surface thereof with an urethane rubber are fitted around the fixed shafts 7, respectively. A separation preventing key 7a is fitted in a free end of each fixed shaft 7 in order to prevent the roll bearing 8 from being separated from the fixed shaft 7.

As shown in Fig. 2, each pedal arm body 20, which is configured to vary in effective length during a 360° rotation thereof, has a length longer than that of a typical bicycle by a length of about 10 cm. The pedal arm body 20 has a bent portion 11 forwardly inclined by an angle of 10 to 15 "with respect to the longitudinal axis thereof, at one end thereof, to which a pedal 19 is rotatably mounted, in order to more smoothly transmit a force applied to the pedal 19. A roll bearing 13 is rotatably mounted to the other end of the pedal arm body 20 in such a fashion that it rolls while being in contact with an associated one of the guide rails 30. The pedal arm body 20 is provided, between the roll bearing 13 and the bent portion 11, with a slitted hollow portion formed with a guide slit 14 extending longitudinally. The guide slit 14 has a length of about 15 cm. The slitted hollow portion of the pedal arm body 20 receives the roll bearings 8 mounted to the associated pedal arm guide member 10 in such a fashion that respective portions of the fixed shafts 7 exposed between the associated guide member body 6 and the roll bearings 8 are received in the guide slit 14. By virtue of this arrangement, the pedal arm body 20 is slidable with respect to the associated pedal arm guide member 10, so that it has a varying mounting position with respect to the drive shaft 1, thus, a varying effective length.

A pair of compression coil springs 15 are also provided to urge an associated one of the pedal arm bodies 20 and the associated pedal arm guide member 10 toward a position at which the pedal arm guide member 10 is positioned at the end of the slit 14 spaced away from the roll bearing 13 to minimize the effective length of the pedal arm body 2C. Each compression coil spring 15 is mounted at one end thereof to the guide member body 6 of the associated pedal arm guide member 10 while being mounted at the other end thereof to a portion of the associated pedal arm body 20 corresponding to the end of the guide slit 14 spaced away from the roll bearing 13. An idle bearing 17 is also mounted to each pedal arm body 20 at a position near the portion of the pedal arm body 20 corresponding to the end of the guide slit 14 spaced away from the roll bearing 13. The idle bearing 17 comes into contact with the guide rail 30 in a state, in which the roll bearing of the pedal arm body is released from the associated guide rail, thereby guiding the rotation of the pedal arm body. Each guide rail 30, which guides an associated one of the pedal arm bodies 20 while being in contact with the roll bearing 13 mounted to the pedal arm body 20, thereby varying the effective length of the pedal arm body 20, includes a curved introduction portion 30a adapted to receive the roll bearing 13 mounted to the pedal arm body 20, thereby allowing a sliding movement of the pedal arm body 20 along the guide rail 30, an intermediate extension portion 30b connected to the introduction portion 30a and adapted to urge the pedal arm body 20 to extend to a maximum effective length against the spring force of the compression coil springs 15, and a return portion 30c connected to the intermediate extension portion 30c and adapted to release the roller bearing 13 of the pedal arm body 20 from the guide rail 30, thereby returning the pedal arm body 20 to have a minimum effective length by virtue of the spring force of the compression coil springs 15. Each guide rail 30 has a gradually varying distance from the drive shaft 1. That is, the distance between the guide rail 30 and the drive shaft 1 is gradually reduced as it extends from the introduction portion 30a to the intermediate extension portion 30b while being gradually increased as it extends from the extension portion 30b to the return portion 30c. By virtue of such a configuration of the guide rails 30, the pedal arm bodies 20 are reduced in effective length as their roll bearings 13 slide along the associated guide rails 30. When the pedal arm bodies 20 are horizontally arranged in parallel to each other, they have a maximum effective length, as shown in Fig. 4b.

In Fig. 1, the reference numeral 32 is a bracket fixedly mounted to the support frame 2 and adapted to support the guide rails 30. In the illustrated case, the guide rails 30 are integral with the support frame 2.

Now, the operation of the length varying device for pedal arms having the above mentioned configuration according to the present invention will be described in conjunction with Figs. 4a to 4d. In an initial state, that is, a state in which the roll bearing 13 of each pedal arm body 20 does not come into contact with the associated guide rail 30, the pedal arm body 20 has a minimum effective length of about 17 cm, corresponding to the standard length of the typical pedal arm, by virtue of the spring force of the compression coil springs 15. When the user applies a rotating force to the pedal of the pedal arm body 20, thereby rotating the pedal arm body 20 about the drive shaft 1, the roll bearing 13 of the pedal arm body 20 comes into contact with the introduction portion 30a of the guide rail 30, and then slides along the introduction portion 30a, as shown in Fig. 4a. In accordance with the guidance of the introduction portion 30a of the guide rail 30, the roll bearing 13 slides upwardly along the guide rail 30, and then enters the extension portion 30b of the guide rail 30. As the roll bearing 13 slides along the extension portion 30b of the guide rail 30, the distance between the roll bearing 13 and the drive shaft 1 is gradually reduced against the spring force of the coil springs 15. That is, the effective length of the pedal arm body 20 is gradually increased by a range D, as shown in Fig. 4b. Preferably, the range D is 9 to 13 cm. Accordingly, the pedal arm body 20 can extend to a maximum effective length of 26 cm when its roll bearing 13 slides along the extension portion 30b of the guide rail 30.

Thus, the length varying device of the present invention can increase the effective pedal arm length by 9 to 13 cm, as compared to the typical pedal arms. Accordingly, it is possible to obtain a maximum drive power using a reduced manual force.

After the roll bearing 13 of the pedal arm body 20 passes the point on the extension portion 30b of the guide rail 30 resulting in the maximum effective length of the pedal arm body 20, the pedal arm body 20 is gradually reduced in effective length by virtue of the spring force of the coil springs 15 because the distance between the guide rail 30 and the drive shaft 1 is gradually reduced. As the roll bearing 13 of the pedal arm body 20 slides along the return portion 30c of the guide rail 30, the effective length of the pedal arm body 20 returns to the minimum length in the initial state, as shown in Fig. 4c.

Two assemblies of the same configuration, each of which includes including one pedal arm guide member 10, one pedal arm body 20, and one guide rail 30, are arranged at opposite sides of the drive shaft 1. Each of these assemblies repeatedly conducts the same operation to transmit a drive power, applied to the drive shaft 1, to the rear wheel of the bicycle via an endless chain 40 wound between the drive sprocket 4 and a driven sprocket (not shown) . Since the assembly has the above mentioned configuration, it is possible to obtain a maximum driving effect using a minimum manual force.

Since the pedal arm body 20 has the bent portion 11 forwardly inclined by an angle of 10 to 15 'with respect to the longitudinal axis thereof, at one end thereof, to which the pedal 19 is rotatably mounted, the kinetic energy applied to the pedal 19 can be more effectively transmitted. Accordingly, it is possible for the user to run the bicycle while correspondingly reducing the consumption of manual power. As apparent from the above description, the present invention provides a length varying device for the pedal arms of a bicycle which has a configuration capable of extending the effective length of each pedal arm to a maximum length at a point where a manual force is applied to the pedal of the pedal arm, and then returning the effective length of the pedal arm to a minimum length, thereby making it possible to generate a maximum drive force using a minimum energy. Thus, the length varying device of the present invention can provide a bicycle capable of achieving an easy running on a slope or for a long distance using a reduced manual force.

Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims .

Claims

WHAT IS CLAIMED IS:

1. A length varying device for pedal arms of a bicycle including a support frame, a drive shaft rotatably fitted in a housing integral with the support frame, and a drive sprocket fixedly mounted to the drive shaft, the pedal arms serving to transmit a manual drive force, applied thereto, to the drive shaft to generate a drive power for the drive sprocket, comprising: a pair of pedal arm bodies constituting the pedal arms of the bicycle, respectively, each of the pedal arm bodies having a pedal mounted to one end of the pedal arm body, a roll bearing mounted to the other end of the pedal arm body, and a hollow longitudinal portion extending longitudinally from a portion of the pedal arm body near the roll bearing toward the pedal by a desired length and having a longitudinal slit, the hollow longitudinal portion serving to allow the pedal arm body to slide longitudinally with respect to the drive shaft while rotating about a rotating axis corresponding to a center of the drive shaft; a pair of pedal arm guide members fixedly mounted, at opposite sides of the drive sprocket, to opposite ends of the drive shaft and adapted to guide the longitudinal sliding movement of the pedal arm bodies, respectively, each of the pedal arm guide members having roll bearings received in the hollow longitudinal portion of an associated one of the pedal arm bodies and adapted to guide the longitudinal sliding movement of the associated pedal arm body; and a pair of guide rails respectively mounted to the support frame in the vicinity of the pedal arm bodies, each of the guide rails coming into contact with the roll bearing provided at an associated one of the pedal arm bodies for at least a part of every rotation of the associated pedal arm body, thereby causing the pedal arm body to slide longitudinally with respect to the drive shaft, so that each of the pedal arm bodies has an effective length varying during the rotation thereof.

2. The length varying device according to claim 1, wherein each of the guide rails comprises: a curved introduction portion arranged at one side of the guide rail and adapted to receive the roll bearing provided at an associated one of the pedal arm bodies, thereby allowing the sliding movement of the associated pedal arm body along the guide rail; a curved return portion arranged at the other side of the guide rail and adapted to release the roller bearing from the guide rail; and an intermediate extension portion arranged between the introduction portion and the return portion and adapted to urge the pedal arm body to extend to a maximum effective length.

3. The length varying device according to claim 1, further comprising: a pair of compression coil springs adapted to urge an associated one of the pedal arm bodies toward a position minimizing the effective length of the associated pedal arm body, each of the compression coil springs being mounted at one end thereof to an associated one of the pedal arm guide members while being mounted at the other end thereof to the associated pedal arm body.

4. The length varying device according to claim 1, wherein each of the pedal arm bodies has a bent portion forwardly inclined by an angle of 10 to 15 "with respect to a longitudinal axis thereof, at one end thereof, to which the pedal is mounted.

5. The length varying device according to claim 1, wherein each of the pedal arm guide members comprises: a guide member body; hollow fixed shafts protruded from a surface of the guide member body facing the pedal arm body and adapted to support the roll bearings of the pedal arm guide member; and separation preventing keys fitted in respective free ends of the fixed shafts and adapted to prevent the roll bearings from being separated from the fixed shafts.

6. The length varying device according to claim 1, wherein each of the pedal arm bodies further has an idle bearing arranged at a portion of the pedal arm body near an end of the hollow longitudinal portion spaced away from the roll bearing mounted to the pedal arm body, the idle bearing serving to come into contact with an associated one of the guide rails in a state, in which the roll bearing of the pedal arm body is released from the associated guide rail, thereby guiding the rotation of the pedal arm body.