WO2000050297A1

WO2000050297A1 - Forward driving gear for bicycle

Info

Publication number: WO2000050297A1
Application number: PCT/KR2000/000147
Authority: WO
Inventors: Chun Kil Park
Original assignee: Chun Kil Park
Priority date: 1999-02-25
Filing date: 2000-02-23
Publication date: 2000-08-31
Also published as: AU2698100A; KR20000017410U; KR200245311Y1

Abstract

A forward driving gear for bicycle comprises a pedal shaft rotatably inserted into a boss of bicycle frame and rotating with the pedal, an internal disc and an external support ring which are separately arranged on the pedal shaft at a prescribed interval for preventing the occurrence of interference during the rotation of the pedal shaft, a reverse driving wheel supported on the inner circumference of the external support ring for a rolling contact, a forward driving wheel which is arranged on a concentric circle of the reverse driving wheel and separated from the reverse driving wheel, and supported on the outer circumference of the external support ring for the rolling contact, and on which a drive sprocket is formed integrally, a directional selecting intermediate gear for changing the direction of rotation of the reverse driving wheel and leading the forward rotation into the drive sprocket, a housing fixed at a location adjacent with the external support ring on the pedal shaft and rotating in the same direction as the pedal bar when the pedal bar rotates in forward or reverse direction, and a two-way ratchet received in the inner circumference of the housing for selectively transferring the rotation of the housing to the forward and reverse driving wheels. The forward driving gear having the above structure can automatically change the direction of rotation when the pedal rotates in the reverse direction, thereby resulting in always driving the bicycle in the forward direction.

Description

FORWARD DRIVING GEAR FOR BICYCLE

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a forward driving gear for bicycle, and more particularly, to a forward driving gear for bicycle, which can automatically change the direction of rotation even when a pedal rotates in the reverse direction, thereby resulting in always driving a bicycle in the forward direction.

Description of the Related Art

In general, a driving gear of bicycle includes a drive sprocket arranged on a pedal shaft, a driven sprocket arranged on a hub spindle of a rear wheel, a chain connecting the sprockets, and a clutch device which is rotated only when a rotation is applied to the drive sprocket in a certain direction, i.e., in the forward direction of a bicycle (normal direction).

When a driver rotates the pedal in the normal direction, the rotation is transferred from the drive sprocket to the driven sprocket through the chain, so that the hub shaft rotates by the clutch device to rotate the rear wheel, and thereby the bicycle drives forward. When the driver does not pedal or rotates the pedal in the reverse direction, the clutch device prevents the rotation from being transferred to the rear wheel, so that the pedal shaft is idly rotated and the bicycle drives continuously forward by an effect of inertia. As previously described above, the conventional driving gear allows the bicycle to drive forward through only the forward rotation of the pedal. Therefore, the driving operation of the pedal is simple, and the pedaling in a single direction during driving for a long time results in fatigue of muscle of the driver's femoral region. With the intention of relaxing the fatigue of the muscle, when the driver does not pedal to take a rest or rotates the pedal in the reverse direction, the bicycle loses the inertia during the idle rotation of the pedal shaft, thereby causing a loss of power.

Recently, various forward driving gears, which allow the bicycle to drive forward whether the pedaling is forward or in reverse, have been developed to solve the problems of the prior art bicycles.

One of the developed and practically used forward driving gears includes a driving part for transferring a driving power of a pedal shaft, which is rotatably inserted into a boss of a frame, to a drive sprocket, a change over part which is detachably mounted on the driving part and changes the reverse and idle rotation of the pedal shaft into the forward rotation to transfer the forward rotation to the drive sprocket, and a change over lever part for detachably mounting the change over part on the driving part according to a driver's manipulation. In the forward driving gear with the above structure, when the driver manipulates a lever of the change over lever part during driving, the change over part is connected to the driving part. Therefore, when the pedal is rotated in the reverse direction, the direction of rotation is changed in the forward direction and the changed direction is transferred to the driving part. The forward driving gear allows the bicycle to drive forward whether the pedaling is forward or in reverse.

However, the driver must manipulate the lever of the change over lever part to connect the change over part to the driving part when the bicycle drives 5 forward by the reverse rotation of the pedal during traveling. Furthermore, if the driver wants to return the bicycle in the forward driving state by the forward rotation of the pedal or to drag and move the bicycle, the driver must manipulate again the lever to release the change over part from the driving part. The manipulation of lever provides the driver with annoyance and trouble in C operation of the bicycle.

Additionally, the forward driving gear has a structure that a R.RM. ratio is reduced in the process of transferring the rotation of the pedal through the change over part to the driving part. The R.RM ratio reduction structure results in preventing the maintenance of the speed of traveling in the same speed as the Ξ forward rotation of the pedal, thereby causing a loss of power and a drop in efficiency.

Moreover, the forward driving gear with complicate structure, in which the change over part and the change over lever part have a number of components, results in a drop in productivity and a rise of manufacturing cost. C

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a forward driving gear for bicycle, which overcomes the problems of the prior arts.

It is another object of the present invention to provide a forward driving gear for bicycle, which automatically changes an internal connection state only through pedaling, to provide driving power in the forward and reverse directions, without manipulation of a lever, thereby allowing a bicycle to drive forward. It is a further object of the present invention to provide a forward driving gear for bicycle, which can reduce the occurrence of load by fraction of components and transfer the driving power in the same R.RM ratio as the forward rotation when the bicycle drives forward by the reverse rotation of a pedal, thereby preventing a loss of power and increasing efficiency. It is a still further object of the present invention to provide a forward driving gear for bicycle, in which a structural part of a single assembly is detachably mounted on a hub shaft of a rear wheel or a pedal shaft, thereby resulting in convenience of repair and replacement of damaged components.

It is another object of the present invention to provide a forward driving gear for bicycle, which has a simple structure using the small number of components to reduce the length of the assembly process of the bicycle, thereby improving the productivity and reducing the manufacturing cost.

It is still another object of the present invention to provide a forward driving gear for bicycle, which allows the rear wheel to rotate in the reverse direction freely, so that the bicycle can be easily towed.

To accomplish the above objects, the present invention provides a forward driving gear for bicycle, including: a pedal shaft which is rotatably inserted into a boss of a bicycle frame and on opposite end portions of which a pair of pedal bars are fixed for rotating with the pedal; an internal disc and an external support ring, which are separately arranged on the pedal shaft at a prescribed interval for preventing the occurrence of interference during the rotation of the pedal shaft; a reverse driving wheel which is arranged between the internal disc and the external support ring and rotates on the pedal shaft and which is supported on the inner circumference of the external support ring for a rolling contact; a forward driving wheel of a ring shape, which is arranged on a concentric circle of the reverse driving wheel, separated from the reverse driving wheel, and supported on the outer circumference of the external support ring for the rolling contact and on which a drive sprocket is formed integrally; a directional selecting intermediate gear which consists of a plurality of gears disposed along the circumferences of the internal disc and the external support ring and is engaged with the reverse driving wheel for changing the direction of rotation of the reverse driving wheel and leading the forward rotation into the drive sprocket; a housing which is fixed at a location adjacent with the external support ring on the pedal shaft and which rotates in the same direction as the pedal bar when the pedal bar rotates in forward or reverse direction; and a two- way ratchet which is received in the inner circumference of the housing for selectively transferring the rotation of the housing to the forward and reverse driving wheels.

BRIEF DESCRIPTION OF THE DRAWINGS

Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which:

Figure 1 is a partially cutaway view in perspective of a forward driving gear according to this invention;

Figure 2 is a sectional view of the forward driving gear of the present invention;

Figure 3 is a perspective view of a structure of a two-way ratchet applied to the forward driving gear;

Figure 4a is a schematic view showing a state that the rotation is transferred according to the engagement state of the two-way ratchet when a pedal rotates in a forward direction (right-hand screw locking direction);

Figure 4b is a schematic view showing a state that the rotation is transferred according to the engagement state of the two-way ratchet when the pedal rotates in the reverse direction (right-hand screw loosening direction); and Figure 5 a is a partially cutaway view showing the engagement state of the two-way ratchet applied to the forward driving gear when the pedal rotates in forward or reverse direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be described in detail hereinafter with reference to the accompanying drawings, wherein the same reference characters designate corresponding parts throughout several views. It is to be understood that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope. A forward driving gear for bicycle according to the present invention is fundamentally installed on a pedal shaft, and a preferred embodiment of this invention will be described hereinafter in detail.

Figures 1 through 5 illustrate a first embodiment that the forward driving gear is mounted on a pedal shaft 5. Figure 1 illustrates a partially cutaway view in perspective of the forward driving gear according to the present invention, and Figure 2 illustrates a sectional view of the forward driving gear. Figure 3 illustrates a perspective view of a structure of a two-way ratchet 70 applied to the forward driving gear. Figure 4a schematically shows a state that the rotation is transferred according to the engagement state of the two-way ratchet when a pedal rotates in a forward direction (right-hand screw locking direction), and Figure 4b schematically shows a state that the rotation is transferred according to the engagement state of the two-way ratchet when the pedal rotates in the reverse direction (right-hand screw loosening direction). Figure 5a is a partially cutaway view showing the engagement state of the two-way ratchet applied to the forward driving gear when the pedal rotates in forward or reverse direction. As shown in the drawings, to transfer driving power to a rear wheel of a bicycle through the medium of a chain, the forward driving gear for bicycle according to the present invention includes: a pedal shaft 5 which is rotatably inserted into a boss 2 of a bicycle frame 1 and on opposite end portions of which a pair of pedal bars 4 are fixed by fixing nuts 6 for rotating with the pedal; an internal disc 10 and an external support ring 20, which are arranged on the pedal shaft 5 at a prescribed interval, and wherein a bearing bush 3 is interposed between the pedal shaft 5 and them for preventing the occurrence of interference during the rotation of the pedal shaft 5; a reverse driving wheel 60 which is arranged between the internal disc 10 and the external support ring 20 and rotates on the pedal shaft 5 and which is supported on the inner circumference of the external support ring 20 through the medium of the bearing bush 3 for a rolling contact; a forward driving wheel 50 of a ring shape, which is arranged on a concentric circle of the reverse driving wheel 60, separated from the reverse driving wheel 60, and supported on the outer circumference of the external support ring 20 for the rolling contact and on which a drive sprocket 40 is formed integrally; a directional selecting intermediate gear 80 which consists of a plurality of gears disposed along the circumferences of the internal disc 10 and the external support ring 20 and is engaged with the reverse driving wheel 60 for changing the direction of rotation of the reverse driving wheel 60 and leading the forward rotation into the drive sprocket 40; a housing 30 which is fixed at a location adjacent with the external support ring 20 on the pedal shaft 5 and which rotates in the same direction as the pedal bar 4 when the pedal bar 4 rotates in forward or reverse direction; and a two-way ratchet 70 which is received in the inner circumference of the housing 30 for selectively transferring the rotation of the housing 30 to the forward and reverse driving wheels 50 and 60. The forward driving wheel 50 has a forward ratchet gear 51 formed on the side circumference thereof and an internal gear 52 formed on the inner circumference adjacent with the directional selecting intermediate gear 80, and the reverse driving wheel 60 has a reverse ratchet gear 61 formed on the side circumference in the opposite direction of the forward ratchet gear 51 and an external gear 62 formed on the outer circumference adjacent with the directional selecting intermediate gear 80.

It is preferable that the drive sprocket 40 is made by stacking a plurality of drive sprockets 40, the diameters of which are differ from each other, for multiple gearshift to regulate a R.RM ratio during a driving of the bicycle.

The housing 30 includes a housing body 31 of a round shape, a latch protrusion 32 for catching the rotating pedal bar 4, and a ratchet ratchet groove 33 formed in the inner circumference of the housing 30 for receiving the two- way ratchet 70. The two-way ratchet 70 includes a ratchet body 71 arranged in a radius direction for engaging the forward ratchet gear 51 or the reverse ratchet gear 61, wedge type end portions 72 which are formed at upper and lower side ends and curved, rotary axis surfaces 73 longitudinally formed on the side ends of the ratchet body 71 and rotating along the inner circumference of the housing 30. The ratchet body 71 is elastically supported from the ratchet ratchet groove 33 by a compression spring 75 disposed on the center portion thereof.

The directional selecting intermediate gear 80 has a pair of gear shafts 82 formed on opposite ends thereof. The gear shafts 82 are rotatably inserted into gear shaft insertion holes 12 and 22 which are respectively formed on the internal disc 10 and the external support ring 20. It is preferable that the directional selecting intermediate gear 80 consists of a plurality of gears at symmetric positions around the pedal shaft 5.

It will be appreciated that a plurality of support rods can be disposed at locations, that the forward and reverse driving wheels 50 and 60 are not interrupted in their rotation, between the internal disc 10 and the external support ring 20 and connected firmly with each other, although it is not illustrated in the drawings.

A plurality of bearing balls 13 are arranged on the contact portions between the internal disc 10 and the forward driving wheel 50, between the forward driving wheel 50 and the outer circumference of the external support ring 20, and between the reverse driving wheel 60 and the external support ring 20 at prescribed intervals for working in the rolling contact without interference from each other during their rotation. The bearing balls 13 are to minimize a loss of power and a friction.

In the drawings, the reference character 11 indicates a pedal shaft insertion hole, 14 a step portion which is formed on the inner surface of the pedal shaft insertion hole 11 of the internal disc 10 for receiving the outer surface of the boss 2, 15 a ball contact surface for seating the bearing balls, and 74 a spring seat for seating the compression spring 75.

The forward driving gear having the above structure is operated as follows.

First, as shown in Figures 4a and 5, when the pedal shaft 5 rotates in the forward direction, the pedal bar 4 pushes the latch protrusion 32 of the housing 30 in the right-hand screw locking direction to rotate the housing 30 in the forward direction. Since the end portion 72 of the two-way ratchet 70 is elastically supported inside the ratchet groove 33 of the housing 30, one of the end portion 72 of the two-way ratchet 70 is engaged with the forward ratchet gear 51 so as to rotate the forward driving wheel 60 in the forward direction. Also, the drive sprocket 40 which is in integration with the forward driving wheel 60 is rotated in the forward direction, so that the bicycle can drive in the forward direction. At this time, the rotation is transferred also to the reverse driving wheel 60 through the directional selecting intermediate gear 80, however, the reverse driving wheel is idly rotated since the reverse ratchet gear 61 is not in engagement with the two-way ratchet 70.

After that, as shown in Figures 4b and 5, when the pedal shaft 5 rotates in the reverse direction, the pedal bar 4 pushes the latch protrusion 32 of the housing 30 in the right-hand screw loosening direction to rotate the housing 30 in the reverse direction. The end portion 72 of the two-way ratchet 70, which is in engagement with the forward ratchet gear 51 inside the ratchet groove 33 of the housing 30, is moved along a slant surface of the forward ratchet gear 51, and then, separated from the forward ratchet gear 51. At the same time, the other end portion 72 of the two-way ratchet 70 is engaged with the reverse ratchet gear 61 of the reverse driving wheel 60. At this time, both end portions 72 of the two-way ratchet 70 are rotated on a central axis of the ratchet body 71 by the rotary axis surface 73, which moves along the curved surface of the ratchet groove 33 in contact with the inner surface of the ratchet groove 33. The reverse ratchet gear 61, which is engaged with the end portion 72 of the two- way ratchet 70, rotates the reverse driving wheel 60 in the reverse direction. The directional selecting intermediate gear 80 which is in engagement with the reverse driving wheel 60 changes the direction of rotation into the forward direction. After all, the forward driving wheel 50 and the drive sprocket 40, which are rotated in engagement with the directional selecting intermediate gear 80, are rotated in the forward direction, so that the bicycle can drive in the forward direction.

Therefore, the forward driving gear for bicycle according to the present invention can automatically change the direction of rotation without an intricate manipulation of a lever, thereby resulting in always driving the bicycle in the forward direction whether the pedaling is forward or in reverse.

The forward driving gear for bicycle according to the present invention is very convenient in operation, and the simplified structure using the small numbers of components results in reducing the length of the assembly process and the manufacturing cost and being easy in repair and replacement of damaged components.

Furthermore, the forward driving gear for bicycle according to the present invention keeps in a low speed ratio when driving in the reverse direction, so that the forward driving gear in itself can perform a gearshift function.

Additionally, the forward driving gear for bicycle according to the present invention can minimize a generation of load due to a friction of components even when the bicycle drives in the forward direction by the reverse rotation of the pedal, thereby resulting in reducing a loss of power and improving the efficiency.

Those skilled in the art will readily recognize that these and various other modifications and changes may be made to the present invention without strictly following the exemplary application illustrated and described herein, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.

Claims

What is claimed is:

1. A forward driving gear for bicycle, comprising: a pedal shaft rotatably inserted into a boss of a bicycle frame, the pedal shaft having a pair of pedal bars fixed on opposite ends thereof exposed from ends of the boss for rotating with the pedal; an internal disc and an external support ring, which are separately arranged on the pedal shaft at a prescribed interval for preventing the occurrence of interference during the rotation of the pedal shaft; a reverse driving wheel arranged between the internal disc and the external support ring and rotating on the pedal shaft, the reverse driving wheel being supported on the inner circumference of the external support ring for a rolling contact; a forward driving wheel of a ring shape, which is arranged on a concentric circle of the reverse driving wheel and separated from the reverse driving wheel, the forward driving wheel being supported on the outer circumference of the external support ring for the rolling contact, wherein a drive sprocket is formed integrally with the outer surface of the forward driving wheel; a directional selecting intermediate gear consisting of a plurality of gears disposed along the circumferences of the internal disc and the external support ring, the directional selecting intermediate gear being engaged with the reverse driving wheel for changing the direction of rotation of the reverse driving wheel and for leading the forward rotation into the drive sprocket; a housing fixed at a location adjacent with the external support ring on the pedal shaft, the housing rotating in the same direction as the pedal bar when the pedal bar rotates in forward or reverse direction; and a two-way ratchet received in the inner circumference of the housing for selectively transferring the rotation of the housing to the forward and reverse driving wheels.

2. A forward driving gear for bicycle as claimed in claim 1, wherein the forward driving wheel has a forward ratchet gear formed on the side circumference thereof and an internal gear formed on the inner circumference adjacent with the directional selecting intermediate gear, and wherein the reverse driving wheel has a reverse ratchet gear formed on the side circumference thereof in the opposite direction of the forward ratchet gear and an external gear formed on the outer circumference adjacent with the directional selecting intermediate gear.

3. A forward driving gear for bicycle as claimed in claim 1, wherein the housing includes a housing body of a round shape, a latch protrusion for catching the rotating pedal bar, and a ratchet ratchet groove formed in the inner circumference of the housing for receiving the two-way ratchet.

4. A forward driving gear for bicycle as claimed in claim 1, wherein the two-way ratchet includes wedge type end portions which are formed at upper and lower side ends of a ratchet body and curved, rotary axis surfaces which are longitudinally formed on the side ends of the ratchet body and rotate along the inner circumference of the housing, and wherein the ratchet body is elastically supported by a compression spring disposed on the center portion thereof.