AU8056294A - Gear-changing system for two-wheel vehicles - Google Patents

Description

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A gear-changing system for two-wheel vehicles The present invention relates to a gear-changing system for two-wheel vehicles, in particular bicycles, according to the preamble of claim 1. Such gear-changing apparatuses are known from practical operation. They comprise up to three chain wheels and up to seven sprocket wheels. In this way twenty-one gears are theoretically possible. In the known gear-changing apparatuses both the chain wheels as well as the sprocket wheels are rigidly mounted. The displacement of the chain is made in the chain wheels by means of a chain-lift fork which pushes the chain onto the desired chain wheel through the gear-changing apparatus. The respective displacement of the chain on the sprocket wheels is made by a derailleur which is actuated by a second gear-changing apparatus and places the chain on the desired sprocket wheel. The disadvantage in known gear-changing systems is the fact that the chain extends particularly obliquely in some gears, and is thus both difficult to switch and subject to very high wear and tear. The consequence of this is that these unfavourably positioned gears can hardly be selected for practical operation, It is the object of the present invention to further develop a gear-changing system of the kind mentioned above in such a way that the chain is disposed approximately in one plane and that thus an inclined course of the chain which is susceptible to wear and tear is avoided. This object is achieved with a gear-changing apparatus of this kind with the characterizing features of claim 1, As a result of the fact that the chain wheels are held axially displaceable relative to the pedal shaft and can optionally be brought by the first gear-changing apparatus relative to the chain lift fork into a number of positions corresponding to the number of chain wheels and that by the second gear-changing apparatus, simultaneously with actuating the derailleur, the chain wheels and the chain-lift fork are axially displaceable relative to the pedal shaft, this being so in such a way that the chain extends in all positions approximately in one plane, the preferable effect is achieved in that the chain is displaced axially only In the distance from one sprocket wheel to the next, with the chain remaining in the plane, and that the chain-lift fork fixes the chain in said plane also during a change of the chain wheels. The switching of the derailleur corresponds to the state of the art and shall not be discussed herein any further. It is preferably provided that the chain wheels are arranged as gear rings which are attached to a bearing disk. Said disk is provided with a plurality of bores which are distanced in the INTEHINUA Anstalt Pntlavb37 FL-9450 VADUZ -2 circumferential direction and through which a respective number of bolts are guided in a sliding manner. The bolts are attached at the one end to a disk attached to the pedal shaft. This provides an exactly guided axial bearing which practically excludes any canting. In a preferred embodiment it is provided that the first gear-changing apparatus is provided with a sleeve to which a roller bearing is attached which carries the bearing disk on the outside, with the sleeve being arranged concentrically to the pedal shaft and receiving in its inner space a flat spiral spring which rests on the one end against a collar attached to the sleeve and on the other end on a casing arranged around the pedal shaft and mounted on the bicycle frame, with the sleeve having a shoulder extending axially parallel to the pedal shaft and projecting into the casing and the control cable of the first gear-changing apparatus being attached to the shoulder, that the second gear-changing apparatus is provided with a sliding block which is held axially displaceable in the casing and is provided with a through-hole for the control cable of the first gear-changing apparatus and a support for the sheath of the control cable, with the sliding block being provided further with a deflection pulley for the control cable of the second gear-changing apparatus whose end is attached to the casing and which is guided through a through-hole in the casing to its outer wall, at which place the sheath of the control cable rests on the casing, and that the sliding block is provided with an arm projecting through a slot of the casing, which arm carries the chain-lift fork and is held in a sliding way on a bolt attached to the bicycle frame, in this way a very compact and stable arrangement is achieved which, by taking into account certain changes in the area of the pedal bearing, can be built into existing bicycles. A preferred embodiment of the invention is now explained in closer detail by reference to a drawing. It shows in a single Figure a cross section through the gear-changing apparatus in the area of the pedal shaft. Only parts that are essential for the invention are shown. With reference to the Fig., the right side of a pedal shaft 10 is shown onto which a disk 19 is screwed rigidly (the screwed connection is not shown), with the arm for the pedals being indicated in the known manner in disk 19. The bearing of the pedal shaft is not shown, because it is well known to the man skilled in the art. Disk 19 carries bolts 18 which project inwardly in an axially parallel manner and are arranged mutually distanced in the circumferential direction. In this embodiment there are eight bolts, Pedal shaft 10 is encompassed at a distance by a sleeve 20. A spiral spring 22 is arranged in the inner space of said sleeve, which spring presses with its one end against an outwardly arranged collar of sleeve 20 and rests with its other end on a casing 23 which Is fixedly mounted on the bicycle frame. The sleeve 20 carries on its outer circumference a roller bearing 21 which is arranged here as a ball bearing. A bearing disk 16 is attached on the outer circumference of the roller bearing 21, which disk is provided with bores which coincide with the bolts 18 concerning their number and position. Bolts 18 are guided therein in a sliding manner. Two chain wheels 11 and 12 are attached to bearing disk 16, with chain wheel 11 being the larger of the two. .ERLINGUA AnStalt l hJi-adi6 FRI4M VABUZ -3 Sleeve 20 is provided with a shoulder 20' extending in the direction of the casing 23. A cable 14 is attached in said shoulder which is associated with the first gear-changing apparatus. A sleeve 14' is arranged around cable 14 which is fixed in a sliding block 24 which is guided in the axial direction in a sliding manner in casing 23. The sliding block 24 carries a deflection pulley 25. A cable 15, which is associated with the second gear-changing apparatus, is guided around said pulley. Cable 16 is encompassed by a sleeve 15' which rests on the exterior of casing 23. The course of the cable is such that it extends from a fixing position on the exterior of casing 23 through a bore in casing 23 over the deflection pulley 26 and is guided outwardly through a further bore in casing 23, with the further bore also representing the receiving position for sleeve 15'. The sliding block 24 Is provided with an arm 26 which projects outwardly through a slot in casing 23 and is guided on a bolt 27 which is attached to the bicycle frame parallel to the axis of the pedal shaft 10. A chain-lift fork 13 is attached to the free end of arm 26, which fork projects in the direction of chain wheel 12 in the represented Figure. The chain (not shown) extends between the two arms of the chain-lift fork 13. The function of the gear-changing system is as follows: If the chain Is to be placed from chain wheel 12 to the larger chain wheel 11, then the control cable 14 is pulled with the first gear-changirig apparatus, which is provided in the known manner with a gear-shift lever in the handling range of the cyclist. As a result of this, sleeve 20 is pressed to the left (according to the drawing) against the pressure of spiral spring 22. The chain-lift fork 13, which is fixed during this process, displaces the chain from the smaller chain wheel 12 to the larger chain wheel 11. It is obvious that during this gear-changing process, which may also be carried out in the opposite direction, the chain remains in the same plane relative to the sprocket wheel. If the chain is to be placed on an adjacent sprocket wheel, the second gear-changing apparatus is actuated. It causes in the known manner a displacement of the chain with the help of the derailleur to the selected sprocket wheel. Simultaneously, control cable 15 is actuated by the second gear-changing apparatus. If, for example, control cable 15 is moved by a respective lever position similar as in the first gear-changing apparatus so that the cable 15 is relieved, then the spiral spring 22 presses the sleeve 20 with the two chain wheels 11 and 12 and the sliding block 24 with the arm 26 and the chain-lift fork 13 to the right (according to the drawing). with the path of the displacement corresponding to one sixth or one seventh of the distance (depending on the number of sprocket wheels) between the centre of the one chain wheel to the centre of the other, so that the chain remains in one plane. During this gear-changing process the chain wheels 12 and 11 and the chain-lift fork 13 do not move relatively with respect to one another, but they are displaced as a whole relative to the bolt 27. With the present invention it is possible to use all gears easily. )ntl

Claims (3)

1. A gear-changing system for two-wheel vehicles, in particular bicycles, with at least two chain wheels (11, 12) of different size which are arranged adjacently on a pedal shaft (10) and can be brought by a first gear-changing apparatus alternately into engagement with a chain by a chain-lift fork (13), and with several differently large sprocket wheels which are arranged adjacent to one another on the rear axle and can be brought by a second gear-changing apparatus with a derailleur alternately into engagement with a chain, with the gear-changing apparatuses being actuatable by one sheathed control cable (14, 15) each, characterized in that the chain wheels (11, 12) are held axially displaceable relative to the pedal shaft (10) and can be brought by the first gear-changing apparatus relative to the chain-lift fork (13) alternately into a number of positions corresponding to the number of chain wheels (11, 12) and that by the second gear-changing apparatus, simultaneously with actuating the derailleur, the chain wheels (11, 12) and the chain-lift fork (13) are axially displaceable relative to the pedal shaft (10), this being so in such a way that the chain extends in all positions approximately in one plane.

2. A gear-changing system as claimed in claim 1, characterized in that the chain wheels (11, 12) are arranged as gear rings which are attached to a bearing disk (16) provided with a plurality of bores (17) distanced in the circumferential direction, with a respective number of bolts (18) being guided through said bores in a sliding manner and being attached with one end to a disk (19) which is attached to the pedal shaft (10).

3. A gear-changing system as claimed in claim I or 2, characterized in that the first gear changing apparatus is provided with a sleeve (20) to which a roller bearing (21) is attached which carries externally the bearing disk (16), with the sleeve (20) being arranged concentrically to the pedal shaft (10) and receiving in its inner space a spiral spring (22) which rests on the one end against a collar attached to the sleeve (20) and on the other end against a casing (23) arranged around the pedal shaft (10) and being mounted on the bicycle frame, with the sleeve (20) being provided with a shoulder (20') which extends axially parallel to the pedal shaft (10) and projects into the casing (23) and with the control cable (14) of the first gear-changing apparatus being attached to the shoulder (20'), that the second gear-changing apparatus is provided with a sliding block (24) which is held axially displaceable in the casing (23) and is provided with a through-hole for the control cable (14) of the first gear-changing apparatus and a support for the sleeve (14') of the control cable (14), with the sliding block (24) further being provided with a deflection pulley (25) for the control cable (15) of the second gear-changing apparatus whose end is attached to the casing (23) and which is guided through a through-hole in the casing (23) to its outer wall, at which position the sleeve (15') of the control cable (15) rests on the casing (23), and that the sliding block (24) is provided with an arm (26) projecting through a slot of the casing (23), which arm carries the chain-lift fork (13) and is held in an axially sliding manner on a bolt (27) attached to the bicycle frame. ePa4W316 FL-491) VADUZ