WO2011012773A1

WO2011012773A1 - Bicycle gear device

Info

Publication number: WO2011012773A1
Application number: PCT/FI2010/050610
Authority: WO
Inventors: Ulf Laxström
Original assignee: Laxstroem Ulf
Priority date: 2009-07-29
Filing date: 2010-07-29
Publication date: 2011-02-03
Also published as: FIU20090284U0; CN202923826U; FI8585U1

Abstract

The invention relates to a gear device for a bicycle and a bicycle including a gear device in question. The invention also relates to a method for manufacturing such a gear device. The gear device (CE) according to the invention includes at least one gear shifting guide (4) the position of which is arranged shiftable at the point of drive cogs (12) of varying sizes for shifting chains (11) onto different drive cogs (12), the gear shifting guide (4) is arranged connectable to the chains (11) without tensioning them substantially and the gear device (CE) is arranged with a chain tensioner (CA) connectable at a distance from the gear shifting guide (4).

Description

Bicycle gear device

Background art

The invention relates to a gear device for a bicycle and a bicycle including a gear device in question. The invention also relates to a method for manufacturing such a gear device.

Multispeed bicycles generally utilise a gear device connected to chains which simultaneously tensions the chains. Its structure is relatively complicated. Assembling such gear devices is also relatively precise work in order to provide a unit reliable and precise in use.

General description of invention

Now has been invented a gear device for a bicycle the technical structure of which is particularly simple.

To reach this object, the invention is characterised by features which are presented in the independent claim. The other claims present some advantageous embodiments of the invention.

In this specification, a bicycle refers to both traditional two-wheeled bicycles one can sit on and other pedalling device arrangements in which the vehicle is movable by pedalling and pedals are connected to chains for rotating a driving wheel. The pedals can be rotatable by feet and/or e.g. by hand. The bicycle can thus be e.g. a unicycle, a tandem bicycle or e.g. a three-wheeled or four-wheeled bicycle. It can also be e.g. a recumbent bicycle or a velomobile.

A drive cog in this specification refers to a cog driving i.e. rotating the wheel. A fork of the driving wheel refers to the fork in the bicycle to which the driving cogs are connected. In a normal two-wheeled bicycle, it is usually the rear fork. In a multi- wheeled bicycle, it is possible to connect two wheels to the fork of the driving wheel. Normally, the drive cogs of the bicycle are arranged such that the outer one is the drive cog equivalent to the highest gear and the inner one is the drive cog equivalent to the lowest gear respectively. In this specification, a shift parallelogram refers to a parallelogram the both ends of which include shift connecting elements for connecting them movably from one end to a housing part and from the other end to a shift guide. The shift parallelogram can include one shift parallelogram plate or two shift parallelogram plates which are then advantageously fastened on both sides of the housing part and the shift guide. The shift guide in this invention is arranged to be a gear shifting guide.

In this specification, a depth direction refers to the direction of the axis or the imagined axis of the driving wheel. A width direction refers to the direction of the connecting line of the driving wheel and the front cog and a height direction is at a 90- degree angle with this and the depth direction.

The gear device according to the invention is intended connectable to the chains of a bicycle for shifting a gear, which bicycle includes at least two drive cogs and at least one chain ring. Typically, there are 5-10 drive cogs and 1-3 chain rings. The gear device includes at least one gear shifting guide the position of which is arranged shiftable at the point of drive cogs of varying sizes for shifting the chains onto different drive cogs, the gear shifting guide is arranged connectable to the chains without tensioning them substantially and the gear device is arranged with a chain tensioner connectable at a distance from the gear shifting guide.

According to an object of the invention, the gear device includes at least two shift parallelograms being in different depth directions in relation to each other, at the first ends of which is connected the housing part and at the second ends of which is connected at least one gear shifting guide the position of which is arranged shiftable substantially in accordance with the direction of the outer surface of a cone formed by the teeth of the drive cogs in order to maintain the distance between the gear shifting guide and the drive cogs substantially equal in various gear positions.

The simple structure provides the advantage of being easy to manufacture and having low manufacturing costs. The gear device according to the invention has a small number of moving parts. Its operation can be easily obtained reliable and precisely adjustable. With this arrangement, the distance between the gear shifting guide and the teeth of the drive cogs remains substantially equal in various gear positions, whereby the operation of the gear device can be obtained particularly precise. The maintenance of the gear device is also technically simple and cost- effective. The invention is particularly suitable for traditional bicycles but it also has a technical advantage in other pedalling devices in which the operation of the gear system is based on shifting the chains. The gear device according to the invention does not include a chain tensioner connected to a traditional gear shifting guide, whereby the structure of the gear shifting guide according to the invention is obtained simpler and sturdier and its operation more precise and responsive as well as more easily adjustable.

According to the invention, the gear device is arranged connectable to the chain tensioner which is connectable to the chains at a distance from the gear shifting guide of the gear device. It is technically advantageous to connect the chain tensioner directly to the chains close to the chain ring. The chain tensioner is then advantageously closer to the chain ring than the drive cogs. The separate chain tensioner at a distance from the gear shifting guide simplifies the structures further as there is no need to connect it separately to the gear shifting guide. It is also possible to optimise the operation of the separate chain tensioner more precisely. The separate chain tensioner also lengthens the contact distances of the chains as well as the drive cogs and chain ring/cogs, whereby it is possible to decrease the load applied on the cogs, the force applied on the chain teeth is decreased and the load coming onto the cogs is divided at a longer distance. This provides both technical and economic advantage.

According to an object of the invention, the shift parallelogram includes one or several shift parallelogram plates, such as advantageously two shift parallelogram plates, the structural thickness of which is 1.5-6 mm, such as advantageously 2-5 mm. This technical arrangement provides a sturdy and functional structure. According to an object of the invention, the shift parallelograms include at least one connector part for connecting an adjuster element, such as a gear cable, in order to select the gear points of the gear shifting guide. Advantageously, the shift parallelograms further include at least one connector part for connecting a return element, such as a return spring, in order to select the gear points of the gear shifting guide. At least one shift parallelogram advantageously includes at least two connector parts for connecting the adjuster element, such as a gear cable, and the return element, such as a return spring, in order to select the gear positions of the gear shifting guide. With these technical arrangements, the gear device is obtained a unit easily adjustable. Advantageously in the depth direction, at the second end of the outer shift parallelogram and at the first end of the inner shift parallelogram is arranged the return element, such as a return spring, and the outer shift parallelogram is connected to the adjuster element, such as a gear cable, in order to select the gear positions of the gear shifting guide. Then, the return element shifts the chains onto the inner drive cog and shifts to a lower gear when pedalling forward. This provides a substantial advantage when e.g. starting to pedal the bicycle or when requiring a speedy gear shift to a lower gear due to a sudden decrease in speed.

According to an object of the invention, at least two shift parallelograms are arranged installable on a plane at an angle with the surface plane of the drive cogs such that the gear shifting guide is arranged movable simultaneously in the depth direction, height direction and width direction in order to maintain the distance between the gear shifting guide and the teeth of the drive cogs substantially equal in various gear positions. The distance between the drive cogs and the gear shifting guide is advantageously about in the range of 2-20 mm, such as e.g. in the range of 2-10 mm or 3-15 mm or 5-20 mm. This arrangement is technically advantageous, because the adjustment of the gear device can be provided extremely precise and reliable in use. The structure is also technically simple and cost-effective to manufacture.

According to an object of the invention, the gear points of the gear shifting guide are indexed. This substantially improves the operation of the gear device making gear shifting precise and quick.

According to an object of the invention, the gear shifting guide is connected to at least one chain guide part for guiding the run of the chains. This further improves the operation of the gear device. Advantageously, the width of the chain guide part is 2- 10 times the thickness of the chains. Then, the chain guide part is provided technically durable and its operation is extremely precise in the adjustment of the run of the chains.

According to an object of the invention, the gear shifting guide of the gear device is arranged directly connectable to the chains of the bicycle. This simplifies the structures as well as improves the technical operation of the device and the accuracy of the gear system. According to an object of the invention, the gear device and the gear shifting guide of the gear device are arranged to shift the chain from within a periphery formed by it. Advantageously, at least the housing part of the gear device is arranged inside the periphery formed by the chains. Then in practice, only the outer part of the gear shifting guide remains outside the periphery formed by the chains. This arrangement is advantageous because the gear device/gear shifting guide are well protected from dents etc. coming from outside and, further, the adjustment of the run of the chains is particularly precise.

According to an object of the invention, the drive cogs are arranged installable outside the fork of the driving wheel of the bicycle. According to an object of the invention, the drive cogs are connected to a drive axle. Advantageously, the bicycle includes a bearing outside the fork of the driving wheel and the drive axle, and the gear device is arranged connectable of its housing part to the fork of the driving wheel, such as advantageously the lower tube of the fork. The connecting means are in that case in the gear device and/or the bicycle. The gear device is then arranged connectable of its housing part to the bicycle at a distance from the drive cogs and/or the possible drive axle. With these arrangements, the gear device can be installed in an advantageous position and the adjustment of the run of the chains is extremely precise. All these arrangements provide both technical and economic advantage. These technical arrangements are extremely advantageous for the part of both the gear device and the drive cogs, because they can be achieved technically simple and operationally precise and sturdy structures.

Particular description of invention

Next, some embodiments of the invention are described in detail with reference to the enclosed drawings.

Rg. 1 shows a bicycle gear device according to the invention when connected to bicycle chains.

Fig. 2 shows a detail of the arrangement according to Fig. 1.

Fig. 1 shows a bicycle B where onto drive cogs 12 and a chain ring 22 are installed chains 11 to which is connected a bicycle gear device CE in order to shift a gear. The gear device CE includes a housing part 1 which is connected to two shift parallelograms 2, 3 at one ends of which is connected one gear shifting guide 4 the position of which is arranged shiftable at the point of the drive cogs 12 of varying sizes in order to shift the chains 1 1 onto different drive cogs 12. The gear device CA is arranged with a separate chain tensioner CA close to the chain ring 22 in order to maintain the chains in a desired tension. The gear device CE is connected of its housing part 1 to a lower tube of a fork 14 of a driving wheel outside it. Thus, the housing part 1 is advantageously in a position inner than the chains 11. The chain ring 22 is connected to pedals 21 on a bottom bracket spindle 23. The gear shifting guide 4 of the gear device CE is at a distance from both a drive axle 13 of the driving wheel i.e. the rear wheel and the chain tensioner CA.

Furthermore in accordance with Fig. 2, the gear device CE includes the housing part 1 which is connected to two shift parallelograms 2, 3 at one ends of which is connected with parallelogram connectors 7 one gear shifting guide 4 the position of which is arranged shiftable substantially in the direction of an outer surface formed by teeth 12t of the drive cogs 12 and which gear shifting guide 4 is arranged connectable to the chains 11 without substantially tensioning them. The distance between the gear shifting guide 4 and the teeth 12t of the drive cogs remains substantially equal in various gear positions. The drive cogs 12 are installed outside the fork 14 of the driving wheel of the bicycle B₁ and the gear device CE and the fork 14 of the driving wheel include outer connecting means 15, 16 in order to connect the gear device CE outside the fork 14 of the driving wheel at a distance from the drive axle 13. Six drive cogs 12 are traditionally arranged such that the innermost one is the drive cog 12 equivalent to the lowest gear and the outermost one is the drive cog 12 equivalent to the highest gear.

The shift parallelograms 2, 3 include connecting parts 8, 9 for connecting a gear cable 10 operating as an adjuster element and a return spring 6 operating as a return element in order to select gear positions of the gear shifting guide 4. The gear shifting guide 4 is connected to two chain guide parts 5 in order to guide the run of the chains. Two shift parallelograms 2, 3 are arranged installable on a plane at an angle with a surface plane 12s of the drive cogs 12 such that the gear shifting guide 4 is arranged movable simultaneously in the depth direction, height direction and width direction in order to maintain the distance between the gear shifting guide 4 and the teeth 12t of the drive cogs substantially equal in various gear positions. This arrangement is advantageous e.g. for the precision and indexing of the gear system. Mobility has been implemented in this case by means of the gear cable 10 and the return spring 6. In the depth direction, at the second end 3 of the outer shift parallelogram 3 and at the first end of the inner shift parallelogram 2 is arranged the return spring 6 as the return element and the outer shift parallelogram 3 is connected to the gear cable 10 as the adjuster element in order to select the gear positions of the gear shifting guide 4. With this arrangement, the return spring 6 advantageously tends to shift the gear to a lower position when shifting the gear.

Claims

1. A gear device for shifting chains (1 1) of a bicycle (B) between two or more drive cogs (12) of varying sizes, characterised in that the gear device (CE) includes at least one gear shifting guide (4) the position of which is arranged shiftable at the point of the drive cogs (12) of varying sizes in order to shift the chains (11) onto different drive cogs (12), and that the gear shifting guide (4) is arranged connectable to the chains (11 ) without substantially tensioning them and the gear device (CE) is arranged with a chain tensioner (CA) connectable at a distance from the gear shifting guide (4).

2. A bicycle gear device according to claim 1 , characterised in that the gear device (CE) includes at least two shift parallelograms (2, 3) being in different depth directions in relation to each other, at the first ends of which is connected a housing part (1) and at the second ends of which is connected at least one gear shifting guide (4) the position of which is arranged shiftable substantially in accordance with the direction of the outer surface of a cone formed by teeth (12t) of the drive cogs (12) in order to maintain the distance between the gear shifting guide (4) and the drive cogs (12) substantially equal in various gear positions.

3. A bicycle gear device according to claim 1 or 2, characterised in that the gear shifting guide (4) of the gear device (CE) is arranged directly connectable to the chains of the bicycle (B).

4. A bicycle gear device according to any one of previous claims, characterised in that the gear device (CE) is arranged connectable of its housing part (1 ) to the bicycle (B) at a distance from the drive cogs (12).

5. A bicycle gear device according to any one of previous claims, characterised in that in the depth direction at the second end (3) of the outer shift parallelogram (3) and at the first end of the inner shift parallelogram (2) is arranged a return element (6), such as a return spring, and that the outer shift parallelogram (3) is connected to an adjuster element (10), such as a gear cable, in order to select the gear positions of the gear shifting guide (4).

6. A bicycle gear device according to any one of previous claims, characterised in that the gear points of the gear shifting guide (4) are arranged indexable.

7. A bicycle gear device according to any one of previous claims, characterised in that the gear shifting guide (4) is connected to at least one chain guide part (5) in order to guide the run of the chains.

8. A bicycle, characterised by a gear device (CE) according to any one of claims 1-7.

9. A bicycle according to claim 8, characterised in that drive cogs (12) and chains (11) are arranged installable outside a fork (14) of a driving wheel of the bicycle (B).

10. A bicycle according to claim 8 or 9, characterised in that the bicycle (B) includes a bearing and a drive axle (13) outside the fork (14) of the driving wheel..

11. A bicycle according to any one of claims 8-10, characterised in that a housing part (1) of the gear device (CE) is arranged substantially inside a periphery formed by the chains (11) of the bicycle (B).

12. A bicycle according to any one of claims 8-11 , characterised in that the housing part (1) of the gear device (CE) and/or the fork (14) of the driving wheel include outer connecting means (15, 16) in order to connect the gear device (CE) of its housing part (1) to the fork (14) of the driving wheel, such as advantageously outside it.

13. A method for manufacturing a gear device for shifting chains (11 ) of a bicycle (B) between two or more drive cogs (12) of varying sizes, characterised by arranging to the gear device (CE) at least one gear shifting guide (4) the position of which is arranged shiftable at the point of the drive cogs (12) of varying sizes in order to shift the chains (11) onto different drive cogs (12), arranging the gear shifting guide (4) connectable to the chains (1 1) without substantially tensioning them and arranging the gear device (CE) with a chain tensioner (CA) connectable at a distance from the gear shifting guide (4).