Planetary gear transmission systems or components – Planet pinion is friction gear – Variable speed ratio
Patent
1992-03-11
1994-02-22
Braun, Leslie A.
Planetary gear transmission systems or components
Planet pinion is friction gear
Variable speed ratio
475192, 476 40, F16H 3708, F16H 1538
Patent
active
052882810
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a continuously variable transmission in which, for one mode or regime of operation the output member of a variator, such as a toroidal race, rolling traction variator, drives an output shaft or other transmission member by way of an epicyclic movement providing power recirculation. For a toroidal race rolling traction variator the variation in transmission ratio is effected by means for altering the rotary axes of rollers which engage toroidal races defined by the input and output members of the variator.
The transmission may have another regime in which the output member of the variator drives the output transmission directly, such as through a simple gearing or chain connection.
In both the aforementioned regimes the transmission ratio between the input and output members in the variator can be continuously varied between a minimum and a maximum. Normally the first regime is employed for speed ratios between reverse and low forward speed and the second regime is employed for higher speeds. Various examples of such transmissions are well known.
BACKGROUND OF THE INVENTION
An earlier International patent application published under serial number WO89/09898 describes a vehicle transmission in which the change over between two regimes, corresponding to the two regimes described above, may be a shockless synchronous change, there being no change in overall transmission ratio during the change in regimes, and the transmission is considerably simplified over earlier vehicle transmission systems, avoiding the use of parallel transmission paths between the power recirculation system and the output transmission member and the consequent necessity of a change in transmission path within the first regime.
The transmission is arranged such that when the first or "low" regime provides a maximum forward speed, the ratio of the variator is at its maximum reduction and this corresponds to the minimum forward speed provided in the "high" regime. A change over between regimes under these circumstances is a shockless synchronous change. Only simple declutching and clutching operations are required for the change over and, where clutches are provided in both the transmission path directly from the output member of the variator to the output transmission member (such as the output shaft) and in the transmission path between the power recirculation system and the said output transmission member, both clutches could be engaged during the change over between regimes.
SUMMARY OF THE INVENTION
An object of the present invention is to provide, for a transmission having at least the first mentioned regime of operation, a selectable transmission path which bypasses the power recirculation system, i.e. the epicyclic system, and provides a fixed transmission ratio.
Another object of the invention is to provide such a selectable transmission path in a transmission which has two regimes as previously described.
According to one aspect of the present invention there is provided a continuously variable transmission in which a transmission unit provides a variable speed ratio between an input member and an output member; the output member is operable to drive an output transmission member through at least a power recirculation system in a selectable regime of the transmission, and through a selectable transmission path providing a fixed ratio drive from the input member to the output transmission member.
The transmission may have a selectable second regime which provides a transmission path from the output member of the variator to the output transmission member.
According to another aspect of the invention there is provided a continuously variable transmission in which a transmission unit provides a variable speed ratio between an input member and an output member; and comprising three selectable transmission paths, a first path coupling the output member to an output transmission member through a power recirculation system, a second path providing a fixed ratio drive from the input m
REFERENCES:
patent: 2239087 (1941-04-01), Erban
patent: 3918325 (1975-11-01), Frost
patent: 4008628 (1977-02-01), Orshansky, Jr.
patent: 4355547 (1982-10-01), Poole et al.
patent: 4638687 (1987-01-01), De Brie Perry
patent: 4691091 (1987-09-01), Perry
patent: 4936165 (1990-06-01), Doyle et al.
patent: 4957474 (1990-09-01), Kemper
patent: 4976666 (1990-12-01), Meyerle
patent: 5139466 (1992-08-01), Perry
Braun Leslie A.
Farley Walter C.
Massey Ryan W.
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