WO2001010706A1

WO2001010706A1 - Automatic bicycle transmission

Info

Publication number: WO2001010706A1
Application number: PCT/KR2000/000800
Authority: WO
Inventors: Yong Dal Kim
Original assignee: Yong Dal Kim
Priority date: 1999-08-04
Filing date: 2000-07-25
Publication date: 2001-02-15
Also published as: AU5855200A; KR20010016792A

Abstract

The present invention relates to an automatic bicycle transmission capable of being automatically shifted according to the rider's pedaling force without operation of another manual control gearshift. The automatic bicycle transmission comprises: a plurality of chain gears provided at a shaft of a bicycle; a derailleur provided at said bicycle wheel and connected said plurality of chain gears by means of a chain; a driving gear connected said chain to be rotated by a rider's pedaling force; a supporting bar movably connected at one end to said driving gear and movably connected at the other end to a frame of the bicycle by hinge; an elastic section provided between said supporting bar and said frame for controlling the pivoting of said supporting bar by expanding and contracting according to the rider's pedaling force; and a shifting wire connected to said supporting bar and said derailleur for moving said derailleur according to the pivoting of said supporting bar.

Description

AUTOMATIC BICYCLE TRANSMISSION

TECHNICAL FIELD

The present invention relates to an automatic bicycle transmission, and more particularly, the present invention relates to an automatic bicycle transmission capable of being automatically shifted according to the rider's pedaling force without operation of another manual control gearshift.

BACKGROUND OF THE INVENTION The bicycle has been being developed since its invention, and today, it is intimately associated with the modern daily life as a transporting means, a sporting means and the like.

When a rider goes up an uphill road on a bicycle, the rider on the bicycle must pedal with greater force than that in pedaling on a plain road in order to go up the uphill road and go ahead.

In a conventional art, in order to easily go up the uphill road with smaller force, a transmission was provided at a rear wheel shaft of a bicycle. The transmission operates to facilitate the high-speed traveling of the bicycle on a plain road or a downhill road.

Fig.l is a side view of a bicycle equipped with a manual transmission according to the conventional art and Fig.2 is a detailed view illustrating a plurality of chain gears and a rear derailleur equipped at a rear wheel of the bicycle . As shown in Fig.l and 2, the conventional bicycle equipped with a manual transmission comprises five chain gears 14a, 14b, 14d, 14c and 14e provided at a shaft 16 of a rear wheel 10 and consisting of first through fifth gears, a rear derailleur 18 provided at rear side of the chain gear 14 for inducing a chain 36 to be shifted from the first chain gear to the fifth chain gear by manipulation of a gearshift 65, the chain 36 connected to the rear derailleur 18, the chain gear 14 and a driving gear 33 to convey driving force, and a shifting wire 60 connected to the rear derailleur 18 and the gearshift 65 to induce the pivoting of the rear derailleur 18.

The fifth, the fourth, the third, the second and the first chain gears 14e, 14d, 14c, 14b and 14a are successively arranged from the center toward the edge of the rear wheel 10. The greater the orders of the 5 chain gears 14 become, the greater the diameters of the chain gears 14 become .

An end of the shifting wire 60 is connected to the rear derailleur 18 and the other end of the shifting wire 60 is connected to the gearshift 65, the gearshift 65 being fixed to a handle part 50 of the bicycle. The shifting wire 60 is pivoted backward and forward in proportion to a pivoting angle of the gearshift 65. Accordingly, the rear derailleur 18 is pivoted by means of movement of the shifting wire 60. The shifting wire 60 is wrapped by wire tube .

On the other hand, at front side of the chain gear 14, that is, between the front wheel 20 and the rear wheel 10, the driving gear 33 is provided, and a shaft 34 is provided at the center of the driving gear 33. The shaft 34 is fixed rotationally to the lower frame 40 of the bicycle. Cranks 35 provided with pedals 31 are fixed to both ends of the shaft 34. Therefore, when the cranks 35 are rotated in pedaling, the shaft 34 is rotated and thus, the driving gear 33 is rotated.

The driving gear 33, the chain gear 14 and the rear derailleur 18 are connected to one another by means of the chain 36. Therefore, when the driving gear33 is rotated, the chain 36 conveys the rotating force of the driving gear 33 to two chain gears 18a, 18b of the rear derailleur 18 and the chain gear 14. On the other hand, the rotating force of the driving gear 33 is generated from the rider's pedaling force and is conveyed to the chain gear 14 to rotate the rear wheel 10.

If the rider manipulates the gearshift 65, the shifting wire 60 is made to be moved backward and forward in proportion to a pivoting angle of the gearshift 65, and the movement of the shifting wire 60 causes the rear derailleur 18 connected to an end of the shifting wire 60 to be pivoted. The pivoting of the rear derailleur 18 makes the chain 36 hung on two chain gears 18a, 18b of the rear derailleur 18 be rotated and makes the chain 36 hung on the chain gear 14 shifted to one of the first through the fifth chain gears according to intention of the rider manipulating the gearshift 65.

In general, when going up an uphill road, the rider manipulates the gearshift 65 so that the chain 36 is hung on the chain gear of which the dimension ratio with respect to the driving gear 33 is small, or of which diameter is large. This makes turns of the chain gear 14 per a turn of the driving gear 33 smaller and thus makes the rotating force of the rear wheel 10 greater. On the other hand, when traveling at high speed, the rider manipulates the gearshift 65 so that the chain 36 is hung on the chain gear of which the dimension ratio with respect to the driving gear 33 is large or of which diameter is small. This makes turns of the chain gear 14 per a turn of the driving gear 33 greater and thus makes the high-speed traveling easy.

However, if a rider does not know well about operation of the gearshift of the manual transmission, it is difficult for the rider to operate the gearshift according to the traveling speed. For this rider, his concentration in operation of the gearshift of the manual transmission makes his concentration in surroundings loose. As a result, the possibility of accident becomes greater. Also, in the manual transmission, there is a shortcoming that manipulation of the gearshift must be often performed according to the traveling condition.

SUMMARY OF THE INVENTION Therefore, the present invention is provided in order to solve the aforementioned problems.

An object of the present invention is to provide an automatic bicycle transmission capable of automatically shifting the gears by using the fact that the rider's pedaling force is different according to the traveling condition.

Other object of the present invention is to provide an automatic bicycle transmission capable of decreasing the possibility of an accident due to the manual operation of the gearshift.

The above objects can be accomplished by an automatic bicycle transmission according to the present invention, the automatic bicycle transmission comprising: a plurality of chain gears provided at a shaft of a bicycle wheel; a derailleur provided at said bicycle wheel and connected said plurality of chain gears by means of a chain; a driving gear connected to said chain and rotated by a rider's pedaling force; a supporting bar movably connected at one end to said driving gear and movably connected at the other end to a frame of the bicycle by hinge; an elastic section provided between said supporting bar and said frame for controlling the pivoting of said supporting bar by expanding and contracting according to the rider's pedaling force; and a shifting wire connected to said supporting bar and said derailleur for moving said derailleur according to the pivoting of said supporting bar.

It is preferable that said elastic section includes a guide rod fixed at an end thereof to said supporting bar to be moved up and down along a guide groove formed in said frame, a height control section coupled to the other end of said guide rod, and an elastic member surrounding said guide rod, both ends of said elastic member being in contact with said height control section and said frame, respectively.

It is more preferable that an elastic force of said elastic member is controlled by moving up and down said height control section coupled to said guide rod of said elastic section.

Also, said elastic section may include a guide rod downward fixed at an end thereof to said frame, a guide groove formed in said supporting bar and inserted by said guide rod so that said inserted guide rod can slide within said guide groove, a height control section coupled to the other end of said guide rod, and an elastic member surrounding said guide rod, both ends of said elastic member being in contact with said height control section and said supporting bar, respectively.

It is more preferable that an elastic force of said elastic member is controlled by moving up and down said height control section coupled to said guide rod of said elastic section. Also, it is preferable that the automatic bicycle transmission further comprises a shifting control section formed in said supporting bar for receiving a positioning member, said positioning member being moved from side to side by means of the elastic force of said elastic member, thereby said positioning member being projected from or inserted into said shifting control section; and a shifting control valve formed in said frame and formed with a plurality of grooves to engage with said projected positioning member. It is still more preferable that a pivoting of said derailleur is varied according to a position of a groove of said plurality of grooves engaging with said positioning member, thereby a traveling condition of said bicycle being varied.

According to the aforementioned present invention, the rider is able to concentrate his attention on the bicycle traveling because the rider need not manually manipulate the gearshift. Also, life times of the bicycle parts can be increased because the abnormal engagement of the chain with the chain gear due to immaturity of the shifting manipulation is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments of the present invention will be explained with reference to the accompanying drawings, in which:

Fig.l is a side view of a bicycle equipped with a manual transmission according to the conventional art; Fig.2 is a detailed view illustrating a plurality of chain gears and a rear derailleur equipped at a rear wheel of a bicycle;

Fig.3 is a side view of a bicycle equipped with an automatic transmission according to a first preferred embodiment of the present invention;

Fig.4 is a detailed view of the automatic transmission shown in Fig.3;

Fig.5 is a detailed view illustrating coupling relationship between a first spring and guide rod and a supporting bar of the automatic transmission shown in Fig.3; and

Fig.6 is a detailed view illustrating the coupling relationship between a first spring and guide rod and a supporting bar of an automatic transmission according to a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The above objects, other objects, features and advantages of the present invention will be better understood from the following description taken in conjunction with the attached drawings.

Now, preferred embodiments of the present invention will be described in detail with reference to the drawings.

First embodiment

Fig.3 is a side view of a bicycle equipped with an automatic transmission according to a first preferred embodiment of the present invention, Fig.4 is a detailed view of the automatic transmission shown in Fig.3, and Fig.5 is a detailed view illustrating coupling relationship between a first spring and guide rod and a supporting bar of the automatic transmission shown in Fig.3.

As shown in Fig.3 through Fig.5, the automatic transmission of the present invention includes a driving gear 133 moved up and down by means of the elastic force of the first compression spring 125, a supporting bar 130a formed at the rear end thereof with the driving gear 133 and connected at the front end thereof to the lower frame 140a of the bicycle by hinge to be pivoted up and down, and a shifting wire 160 connected at both ends thereof to the rear derailleur 18 and the supporting bar 130a, respectively. Both ends of the shaft 134 of the driving gear 133 are connected to one end of cranks 35, and the other ends of the cranks 135 are connected pedals 131. The shaft 134 of the driving gear 133 is received rotationally in the rear end of the supporting bar 130a. On the other hand, the front end of the supporting bar 130a is connected to the hinge axis 155 of the hinge section 150 formed in the lower frame 140a of the bicycle and is pivoted up and down about the hinge axis 155. Also, at a predetermined position distant from the position of the supporting bar 130a provided with the driving gear 133, the guide rod 120a is upward fixed to the supporting bar 130a. The guide rod 120a is moved up and down along the guide groove 142 formed in the lower frame 140a of the bicycle. A control screw 122 is coupled to the upper end of the guide rod 120a so that the elastic force of the first compression spring 125 is controlled by a rider's pedaling force. The first compression spring 125 is provided between the control screw 122 and the lower frame 140a while surrounding the guide rod 120a. Therefore, the supporting bar 130a is pivoted up and down about the hinge axis 155, thereby the first compression spring 125 expanding and contracting. On the other hand, at front side of the guide rod 120a, an end of the shifting wire 160 is fixed to the supporting bar 130a and the other end of the shifting wire 160 is connected to the rear derailleur 18 provided at the rear wheel 10.

In the bicycle constructed as described above, the rider's pedaling force is divided into a force for rotating the driving gear 133 and a force for downward pivoting the supporting bar 130a. Thus, if the rider's pedaling force become greater, the first compression spring 125 is compressed, the shifting wire 160 connected to the supporting bar 130a is downward moved in proportion to the pivoting angle of the supporting bar 130a to pivot the rear derailleur 18. On the other hand, if the rider's pedaling force become weaker, the supporting bar 130a is pivoted toward the lower frame 140a by the restoring force of the compressed first compression spring 125, the shifting wire 160 is moved toward the rear side, that is, the rear derailleur 18, and thus the rear derailleur 18 is restored by its spring.

The construction of the rear derailleur 18 of the present invention is equal to the conventional construction of Fig.2, except that the other end of the shifting wire 160 connected to the rear derailleur 18 is fixed to the lower frame 140a, not to the handle. The reference numbers of respective parts of the rear derailleur is equal to those in Fig.2.

The shifting wire 160 is wrapped with a wire tube 165 and both ends of the wire tube 165 are fixed to the lower frame 140a and the rear derailleur 18, respectively.

The shifting control section 190 extended from the rear end of the supporting bar 130a receives a second compression spring 192 and en end of the second compression spring 192 is provided with a positioning member 194 of which shape is cylinder-like . The positioning member 194 is influenced by the restoring force of the second compression spring 192 and a part of the positioning member 194 is projected from the shifting control section 190. Here, when the force which is applied from the outer side of the shifting control section 190 to the positioning member 194 become equal to or greater than the restoring force, the positioning member 194 is received in the shifting control section 190 and when the applied force is removed, the part of the positioning member 194 is projected from the shifting control section 190 by means of the restoring force. At that time, the shifting control section 190 is fixed so that the positioning member 194 directs outside of the rear end of the supporting bar 130a.

The shifting control valve 180 is downward provided at the lower frame 140a of the bicycle and provided to be in contact with the positioning member 194 of the shifting control section 190. 5 grooves 181a, 181b, 181c, I81d and 181e having a semicircle cross-section are formed in a vertical direction on a surface of the shifting control valve 180 in contact with the positioning member 194 and are parallel to one another in a length direction. The part of the positioning member 194 projected from the shifting control section 190 engages with one 181c of the 5 grooves 181a, 181b, 181c, 181d and 181e. The uppermost groove 181a of the 5 grooves 181a, 181b, 181c, 181d and 181e is a first gear groove and the rest grooves 181b, 181c, 181d and 181e are a second gear groove, a third gear groove, a fourth gear groove and a fifth gear groove, respectively.

A stopper 185 is formed at the lower end of the shifting control valve 180, which prevents the positioning member 194 of the shifting control section 190 from being separated below the fifth gear groove 18le of the shifting control valve 180.

Accordingly, as the supporting bar 130a is pivoted up and down, the positioning member 194 moves up and down along the grooves formed on the shifting control valve 180. As shown in Fig.4, when the positioning member 194 positioned at the third gear groove 181c goes over a projection between the third gear groove 181c and the fourth gear groove 181d, the positioning member 194 is received in the shifting control section 190. When positioned at the fourth gear groove 18Id, the positioning member 194 is projected by means of the restoring force of the second compression spring 192 to engage with the fourth gear groove 181d. Therefore, the supporting bar 130a is positioned corresponding to the fourth gear groove 18Id engaging with the positioning member 194.

As the positioning member 194 moves from groove to groove on the shifting control valve 180, the supporting bar 130a is pivoted with a distance between the grooves and the shifting wire 160 moves in proportion to the distance between the grooves. At that time, moved distance of the shifting wire 160 is set so that the rear derailleur 18 is pivoted to shift the chain 36 from one chain gear to other chain gear. Therefore, if the positioning member 194 is positioned at a specific groove, the rear derailleur 18 shifts the chain 36 to the chain gear corresponding to the specific groove.

Now, operation of the automatic bicycle transmission according to the first embodiment of the present invention will be described.

When a rider on the bicycle pedals, the driving gear 133 is rotated by means of the rider's pedaling force.

For example, suppose that shifting from the third gear to the fourth gear or the second gear is performed. Rotation of the driving gear 133 is conveyed through the chain 36 to the third chain gear 14c of the first through the fifth chain gears 14a, 14b, 14c, 14d and 14e and rotation of the third chain gear 14c is conveyed to a shaft of the rear wheel 10 to advance the bicycle. When going up an uphill road, the rider pedals with greater force than that in traveling on a plain road. This force rotates the driving gear 133 and pivots the supporting bar 130a to compress the first compression spring 125.

At that time, if the force downward pivoting the supporting bar 130a is equal to or greater than the force necessary to shift the positioning member 194 of the shifting control section 190 from the third gear groove 181c to the fourth gear groove 181d, the supporting bar 130a is pivoted on the hinge axis 155 with a distance between the third gear groove 181c and the fourth gear groove 18Id and the shifting wire 160 connected to the supporting bar 130a moves downward. Then, the rear derailleur 18 fixed with an end of the shifting wire 160 is pivoted to shift the chain 36 from the third chain gear 14c to the fourth chain gear 14d.

On the other hand, when going down a downhill road, the rider's pedaling force becomes weak. Then, the restoring force of the first compression spring 125 pivots the supporting bar 130a toward the lower frame 140a. At that time, if the restoring force is equal to or greater than the force shifting the positioning member 194 from the third gear groove 181c to the second gear groove 181b of the shifting control valve 180, the supporting bar 130a is pivoted toward the lower frame 140a. Therefore, the shifting wire 160 moves up and the chain 36 is shifted to the second chain gear 14b by means of the rear derailleur 18.

Second embodiment Fig.6 is a detailed view illustrating the coupling relationship between the first spring and guide rod and a supporting bar of an automatic bicycle transmission according to a second preferred embodiment of the present invention. As shown in Fig.6, the construction of the automatic bicycle transmission of the second embodiment is equivalent to that of the automatic bicycle transmission of the first embodiment, except for the position of the guide rod, the position of the guide groove and the position of the first compression spring. Therefore, in the same elements, the detailed description thereof is omitted and the same reference numbers are given.

The automatic bicycle transmission of the second embodiment of the present invention includes a guide rod 120b fixed downward at an end thereof to a lower frame 140b of the bicycle, a guide groove 132 formed on a supporting bar 130b to be inserted by the guide rod 120b, a height control screw 122 to be coupled to the other end of the guide rod 120b, and a first compression spring 125 surrounding the guide rod 120, both ends of the first compression spring 125 being in contact with the supporting bar 130b and the height control screw 122, respectively.

When pedaling, the supporting bar 130b is pivoted downward along the guide rod 120b and the first compression spring 125 in contact with the lower part of the supporting bar 130b and the upper surface of the height control screw

122 is compressed.

If the rider' s pedaling force becomes weak, the supporting bar 130b is pivoted upward, that is, toward the lower frame 140b of the bicycle along the guide rod by means of the restoring force of the first compression spring 125.

The pedaling force is varied by the rider's age and sex. Therefore, in order to be automatically shifted by the rider's pedaling force, the restoring force of the first compression spring 125 can be controlled by means of manipulation of the height control screw 122 coupled to the end of the guide rod 120a and 120b.

The end of the shifting wire 160 may be connected to a front derailleur, not the rear derailleur to vary the traveling conditions.

As described above, the automatic bicycle transmission according to the present invention has an advantage that the rider is able to concentrate his attention on the bicycle traveling because the rider need not manually manipulate the gearshift.

Also, the automatic bicycle transmission according to the present invention has an advantage that life times of the bicycle parts can be increased because the abnormal engagement of the chain with the chain gear due to immaturity of the shifting manipulation is prevented.

Although technical spirits of the present invention has been disclosed with reference to the appended drawings and the preferred embodiments of the present invention corresponding to the drawings has been described, descriptions in the present specification are only for illustrative purpose, not for limiting the present invention.

Also, those who are skilled in the art will appreciate that various modifications, additions and substitutions are possible without departing from the scope and spirit of the present invention. Therefore, it should be understood that the present invention is limited only to the accompanying claims and the equivalents thereof, and includes the aforementioned modifications, additions and substitutions .

Claims

CLAIMS What is claimed is:

1. An automatic bicycle transmission, comprising: a plurality of chain gears provided at a shaft of a bicycle wheel; a derailleur provided at said bicycle wheel and connected said plurality of chain gears by means of a chain; a driving gear connected to said chain and rotated by a rider's pedaling force; a supporting bar movably connected at one end to said driving gear and movably connected at the other end to a frame of the bicycle by hinge; an elastic section provided between said supporting bar and said frame for controlling the pivoting of said supporting bar by expanding and contracting according to the rider's pedaling force; and a shifting wire connected to said supporting bar and said derailleur for moving said derailleur according to the pivoting of said supporting bar.

2. The automatic bicycle transmission according to claim 1, wherein said elastic section includes a guide rod fixed at an end thereof to said supporting bar to be moved up and down along a guide groove formed in said frame, a height control section coupled to the other end of said guide rod, and an elastic member surrounding said guide rod, both ends of said elastic member being in contact with said height control section and said frame, respectively.

3. The automatic bicycle transmission according to claim 1, wherein said elastic section includes a guide rod downward fixed at an end thereof to said frame, a guide groove formed in said supporting bar and inserted by said guide rod so that said inserted guide rod can slide within said guide groove, a height control section coupled to the other end of said guide rod, and an elastic member surrounding said guide rod, both ends of said elastic member being in contact with said height control section and said supporting bar, respectively.

4. The automatic bicycle transmission according to claim 2, wherein an elastic force of said elastic member is controlled by moving up and down said height control section coupled to said guide rod of said elastic section.

5. The automatic bicycle transmission according to claim 3 , wherein an elastic force of said elastic member is controlled by moving up and down said height control section coupled to said guide rod of said elastic section.

6. The automatic bicycle transmission according to claim 1, further comprising: a shifting control section formed in said supporting bar for receiving a positioning member, said positioning member being moved from side to side by means of the elastic force of said elastic member, thereby said positioning member being projected from or inserted into said shifting control section; and a shifting control valve formed in said frame and formed with a plurality of grooves to engage with said projected positioning member.

7. The automatic bicycle transmission according to claim 6, wherein a pivoting of said derailleur is varied according to a position of a groove of said plurality of grooves engaging with said positioning member, thereby a traveling condition of said bicycle being varied.