Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Gear shiftable axially to disconnect or vary ratio
Patent
1997-01-27
1998-06-23
Ta, Khoi Q.
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Gear shiftable axially to disconnect or vary ratio
475300, 192 6A, B62M 1116, F16H 366
Patent
active
057697507
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an epicyclic change gear system for a bicycle or the like.
It is known in the art to provide a five speed epicyclic change speed gear hub for a bicycle by utilising compound planet gears engaged with a common gear ring and each cooperable with a respective sun gear selectively engageable therewith in a drive transmission mode.
In such an arrangement the sun gears are rotatably and slidably mounted on the hub spindle for unitary movement in the axial direction thereof for the selective dogged engagement of one or other of the sun gears with a respective formation non-rotatably fixed to the spindle.
The planet cage of the aforesaid arrangement is connectable with the hub shell, so as to provide a drive transmission from the planet cage to the hub shell according to hub condition, by means of axially movable pawls mounted in the planet cage and cooperable with ratchet teeth provided in a hub end cap. The gear ring is connectable with the hub shell through radial pawls.
It is also known from our copending Patent Application No. GB-A-2249364 for a sun gear to be axially fixed with respect to the spindle and to provide a selector key movable axially of the spindle for selective engagement with a respective one of the sun gears so as non-rotatably to secure that sun gear to the spindle.
An object of the present invention is to provide the capability for an even greater range of gears.
According to the present invention, there is provided an epicyclic change speed gear comprising a fixed spindle, an input member and an output member, planet pinions disposed in a planet cage, a gear ring is operatively connected to the output member or input member, a clutch operative to connect the input member to the planet cage or the input member to the gear ring, side-by-side sun pinions rotatable on the spindle any one of which is operable to provide a reaction member when locked to the spindle and a gear selector key disposed radially inwardly of said sun pinions and adapted for selective cooperative engagement with said only one of the said sun pinions on movement of the selector key in the axial direction of the hub in order to lack the corresponding sun pinion to the spindle to provide the reaction member, and means for operating the selector key to provide said selective cooperative engagement characterised in that the means for operating the selector key comprises a sleeve disposed for rotational movement relative to the spindle relative rotational movement of the sleeve resulting in axial movement of the selector key.
The precharacterising portion of the invention as outlined above is based upon the above mentioned patent application No. GB-A-2249364.
In a preferred embodiment of the invention, at least one axial edge thereof is angled to the axis of the sleeve so that on rotation of the sleeve on the spindle the axial extent of the sleeve between a fixed point on the spindle and the selector key is varied thereby moving the key axially with respect to that fixed point. A pin may be attached to the spindle at the fixed point to form an abutment for the sleeve. The pin may be rotatable with respect to the sleeve. Advantageously, both axial ends of the sleeve may be similarly angled so that the axial displacement of the key is doubled for a given rotational movement of the sleeve. The or each angled edge may be formed with steps corresponding to given axial positions of the key in which given sun pinions are locked to the spindle. An outer cam follower is keyed to the sleeve. This cam follower is locked with respect to the sleeve in the rotational sense, but may move axially with respect thereto. If desired the sleeve could be made with its axial ends at right angles to the axis of the sleeve. Rotational thereof would then only produce movement of the outer cam follower and not of the key thus reducing the number of gear ratios provided with one sun pinion to two or three. In operation the cam follower moves a clutch away from the planet cage against the reaction of an outer sleeve cam. A
REFERENCES:
patent: 1249659 (1917-05-01), Olsen
patent: 1422508 (1922-07-01), Wheeler
patent: 1490644 (1924-04-01), Sturmey et al.
patent: 2301852 (1942-11-01), Brown
patent: 3438283 (1969-04-01), Schwerdhofer
patent: 4721013 (1988-01-01), Steuer et al.
Sturmey-Archer Limited
Ta Khoi Q.
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