Multi-speed power transmission with a mechanical clutch

Details Multi-speed power transmission with a mechanical clutch Multi-speed power transmission with a mechanical clutch

1999-10-04

2001-04-10

Marmor, Charles A. (Department: 3681)

Planetary gear transmission systems or components

With means to vary drive ratio or disconnect drive

Plural elements selectively braked

C475S303000

Reexamination Certificate

active

06213909

ABSTRACT:

TECHNICAL FIELD
This invention relates to multi-speed power transmissions and more particularly to such transmissions employing a forward/reverse clutch mechanism.
BACKGROUND OF THE INVENTION
Vehicle powertrains incorporate a multi-speed, automatic shifting power transmission to increase the effectiveness of the operating range of the internal combustion engine to provide for improved fuel economy and more efficient highway speed operation. The number of forward gear ratios available through the transmission has increased from two to five. The increased number of gear ratios requires an increased size and number of components at the transmission.
Many of the currently-available automatic shifting transmissions incorporate two or three planetary gear sets that are interconnected either directly or through friction devices to provide the desired gear ratios. The number of mechanical members increases with the number of gear ratios. Generally, an added gear ratio requires at least one additional friction device with the accompanying complexity in the control function. The added friction device (either a clutch or a brake) requires a plurality of friction plates, a piston, and return springs. These items require an increase in assembly time for the transmission. In the case of an added clutch, a housing must be provided, and a means for insuring against “centrifugal drift on” is necessary. In the case of a brake, additional machining in the transmission housing is required.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved five-speed planetary transmission having a forward/reverse mechanical clutch. In one aspect of the present invention, a powertrain has a planetary transmission including two planetary gear sets selectively interconnectable through a mechanical clutch. In another aspect of the present invention, one of the planetary gear sets is a simple planetary gear set having a sun gear member that is connectable with a sun gear of the other planetary gear set or the transmission input shaft through the mechanical clutch.
In yet another aspect of the present invention, the other planetary gear set is a compound planetary gear set having a carrier assembly member continually connected with the transmission input shaft and selectively connectable with the sun gear of the simple planetary gear set. In still another aspect of the present invention, the sun gears of both planetary gear sets are selectively connectable to a stationary housing through a brake when the mechanical clutch is interconnecting them. In a further aspect of the present invention, the mechanical clutch connects the sun gear of the simple planetary gear set with the input shaft during reverse operation, to the other sun gear during all forward operations and has a neutral position during a transmission neutral condition.


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patent: 3330303 (1985-03-01), None

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