Transmission unit for motor vehicles
AssigneeFiat Auto S.p.A.
InventorsGiorgio Lupo, Pier G. Castelli
Life of this patent
Estimating the term…
Abstract
A motor vehicle transmission unit provided with an automatic variable ratio transmission mechanism and a supplementary fixed ratio transmission mechanism which transmits torque from an input shaft to an output shaft of the unit in conditions of low speed and high torque. A free wheel clutch allows the variable ratio transmission mechanism to take over the drive when the speed increases, this being accomplished by means of an automatic speed sensitive clutch which engages when the speed of the output shaft reaches a predetermined threshold valve. A torque converter or other progressive coupling device links the input shaft of the unit, via an isolating friction clutch, to the fixed ratio transmission mechanism.
Claims17
In a transmission unit for a motor vehicle, of the type comprising:
- a drive shaft,
- a driven shaft for connecting said transmission unit to the propulsion members of the vehicle, and
- an automatic, variable ratio, transmission mechanism for interconnecting the drive shaft and the driven shaft,
- the improvement wherein there is provided a first series arrangement comprising:
- an automatically controlled friction clutch disposed mechanically in series with said variable ratio transmission mechanism, and
- control means for said friction clutch sensitive to the angular velocity of said driven shaft and operating to maintain said friction clutch disengaged below a predetermined angular velocity of said driven shaft and engaged above this predetermined angular velocity, and,
- a second series arrangement comprising:
- (i) a fixed ratio transmission mechanism and,
- (ii) a free wheel clutch, disposed mechanically in parallel with said first series arrangement of said controlled friction clutch and said variable ratio transmission mechanism between said drive shaft and said driven shaft, said free wheel clutch operating to transmit drive from said drive shaft to said driven shaft through said fixed ratio transmission mechanism when said controlled friction clutch is disengaged.
Dependencies are inferred from the claim text.