Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural drive ratios other than unity
Patent
1995-12-26
1998-09-29
Ta, Khoi Q.
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural drive ratios other than unity
475298, B62M 1116, F16H 366
Patent
active
058139370
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention concerns epicyclic change speed gear hubs for bicycles and the like, and has more particular reference to hubs having two or more sun gears selectively engageable with respective gear elements of compound planet gears in a drive transmission mode.
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 shelf 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.
A further arrangement in which a selector key is moveable axially of a spindle is described in EP-A-0 180 076. This key moves in a slot which extends through the spindle and which is operative to control a clutch. In addition a selector sleeve having dogs is provided to move axially on splines on the spindle in order to lock one or other of the sun gears to the spindle. This is a complex arrangement which is difficult to produce.
The object of the present invention is to provide an alternative means whereby the respective sun gears might selectively be brought into a drive transmission mode, and preferably one such as will allow of the use of a single cable in effecting gear change through the full range of available 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 which may be operatively connected to the output member or the input member, a gear ring which may be 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 one or other 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 one or other of the said sun pinions on movement of the selector key in the axial direction of the hub in order to lock the corresponding sun pinion to the spindle to provide the reaction member, the selector key including a support rod, first and second body parts mounted on said rod for limited relative movement in the axial direction thereof, and resilient means resisting said relative movement characterised in that in addition to locking one or other of the sun pinions the key also serves to control the operative condition of the clutch and thereby the connection of the input member to the planet cage or the gear ring as the case may be.
According to a preferred feature, each body part includes an outward extending dog for cooperative engagement with splines provided internally of the sun pinions.
According to a still further preferred feature, the sun pinions are resiliently loaded into abutting side-by-side disposition.
According to a still further preferred feature, the gear selector key is movable into axial abutment with a selector sleeve of the epicyclic
REFERENCES:
patent: 3908807 (1975-09-01), Ozaki et al.
patent: 3973451 (1976-08-01), Kine
patent: 5399128 (1995-03-01), Nurberger
patent: 5445573 (1995-08-01), Nurnberger
Sturmey-Archer Limited
Ta Khoi Q.
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