Interrelated power delivery controls – including engine control – Transmission control – Differential transmission
Patent
1998-11-30
2000-02-29
Marmor, Charles A.
Interrelated power delivery controls, including engine control
Transmission control
Differential transmission
475201, 475202, 475205, 180248, 74665GC, B60K 17346
Patent
active
060303123
DESCRIPTION:
BRIEF SUMMARY
The invention relates to motor vehicle power trains and is particularly concerned with power trains of four wheel drive vehicles of the type which have a longitudinally mounted engine.
Known power trains of conventional four wheel drive vehicles typically comprise a change speed transmission mounted axially in line with the engine and a transfer transmission which is mounted directly on the change speed transmission to drive front and rear differentials through propshafts offset from the engine and the change speed transmission. Alternatively, a separate transfer transmission is spaced from the change speed transmission and connected to it through a short universally jointed propshaft.
Packaging of power trains in motor vehicles is of increasing importance particularly as vehicles become more compact and available space decreases. This creates a conflict for the vehicle designer between providing adequate accommodation for the driver and passengers and mounting the power train components in an arrangement most appropriate for their function of driving the vehicle.
A power train is described in FR-A-2 695 880 which shows a transmission which is intended for a sports car and the object is to move the weight of the transmission assembly close to the rear wheels so that there is a balanced distribution of load between the two axles of the vehicle. To fulfil this object of weight distribution, FR-A-2 695 880 couples the transmission assembly directly to the rear differential casing so that the rear output from the center differential is taken directly by the bevel pinion shaft. This causes more problems in providing adequate accommodation for the passengers and luggage and adds to the polar moment of inertia of the vehicle, affecting ride and handling.
An object of the present invention is to provide a motor vehicle power train which helps to optimize the available space without any of the disadvantages outlined above.
According to one aspect of the invention a power train for a motor vehicle is characterised in that the transmission assembly is separate from the rear differential and placed at or near the center of the vehicle and is spaced from the rear differential by a rear propshaft which drivably connects the rear differential to the rear rotary output.
The change speed transmission may be coaxial with the hollow output shaft, an input transmission being adapted to transmit drive from the drive input to the input shaft of the change speed transmission, in which case the input transmission and the auxiliary output transmission are conveniently arranged at the same end of the transmission assembly. This arrangement is particularly suitable where the change speed transmission is an epicyclic type automatic transmission or a toroidal type CVT.
Alternatively, the change speed transmission may be a layshaft type having an input shaft coaxial with the rotary input and axially offset from the hollow output shaft. This arrangement is particularly suitable where the change speed transmission is a constant mesh type, e.g. sychromesh or is a belt and pulley type CVT.
The transfer transmission may include an epicyclic final drive having a sun gear connected to the hollow output shaft and a planet gear carrier for transmitting drive to the center differential, in which case the epicyclic final drive may provide a plurality of selectable ratios.
In one arrangement according to the invention the transmission assembly is spaced from the engine, the rotary input being connected to the engine by an input propshaft, in which case a drive coupling (e.g. torque converter or friction clutch) in the drive between the engine and the transmission assembly can be mounted on the engine so as to be operable to transmit drive to the transmission assembly through the input propshaft. A bell housing for the drive coupling can be mounted on the engine and, as an alternative to independent mounting of the engine and the transmission assembly, the bell housing and the transmission assembly can be connected by a tubular housing which surrou
REFERENCES:
patent: 3235021 (1966-02-01), Hill
patent: 4671136 (1987-06-01), Katayama
patent: 4756381 (1988-07-01), Renaudin
patent: 4805720 (1989-02-01), Clenet
patent: 5640882 (1997-06-01), Mueller
patent: 5704866 (1998-01-01), Pritchard et al.
Ebrey John Samuel
Nesbitt David Charles
Tickle David John
Woolmer Clive David
Marmor Charles A.
Parekh Ankur
Rover Group Limited
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