Motor vehicle power train

Details Motor vehicle power train Motor vehicle power train

1998-11-13

2001-06-26

Boehler, Anne Marie (Department: 3618)

Motor vehicles

Having four wheels driven

With differential means for driving two wheel sets at...

C475S206000

Reexamination Certificate

active

06250411

ABSTRACT:

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. Hence an object of the present invention is to provide a motor vehicle power train which helps to optimise the available space.
According to one aspect of the invention there is provided a power train for a motor vehicle having a pair of front wheels and a pair of rear wheels, the power train comprising an engine which, in use, is mounted longitudinally in the vehicle, a change speed transmission drivably connected to the engine, a front differential disposed, in use, between the front wheels and drivably connected thereto, a rear differential disposed, in use, between the rear wheels and drivably connected thereto and a transfer transmission mounted on the change speed transmission and drivably connected to the front differential through a front propshaft and to the ear differential through a rear propshaft, the change speed transmission having an input shaft arranged to receive drive from the engine at one end of the change speed transmission and an output shaft axially offset from the input shaft and having a drive output at the opposite end of the change speed transmission, the transfer transmission being arranged at said opposite end of the change speed transmission for receiving the drive output therefrom and including a centre differential having differential output shafts drivably connected to the front and rear propshafts and axially offset from the input shaft and from the change speed transmission output shaft, characterised in that the engine is, in use, mounted adjacent one end of the vehicle and that the change speed transmission is spaced from and drivably connected to the engine by an input propshaft.
Conveniently the change speed transmission includes constant mesh gear trains each comprising a pair of gears, one gear of each pair being mounted on the input shaft and the other of each pair being mounted on the output shaft, in which case one gear of each pair may be fixed to or integral with the input shaft, the other gear of each pair being selectably connected to the output shaft.
Similarly, the transfer transmission may includes constant mesh gear trains each comprising a pair of gears, one gear of each pair being mounted on the output shaft and the other of each pair being mounted on the centre differential, in which case said one gear of each pair may be fixed to or integral with the centre differential, the other gear of each pair being selectably connected to the output shaft.
A drive coupling such as a clutch or torque converter may be mounted on the engine and the input propshaft be interposed between the drive coupling and the input shaft of the change speed transmission
In order to minimise costs, a change speed transmission used in the present invention can be based on one which has been initially designed for use on front wheel drive motor cars with transverse engines. Such transmissions have been increasingly popular since about 1960. Since then, most drive lines have comprised a change speed transmission mounted in line with the engine, an input shaft of the transmission being axially aligned with the engine and an output shaft being parallel with and spaced from the input shaft with the input shaft and the output shaft both extending from the change speed transmission at the same end. The output shaft has a gear which directly drives a gear mounted on a cage of a differential mounted on the rear of the change speed transmission, the differential having drive shafts directly connected to the front wheels. The change speed transmission used in the conventional type of four wheel drive power trains described above was usually able to use a casing, rotary drive components and selector components substantially identical to those produced for the change speed transmission used for conventional front engine, rear wheel drive motor vehicles where the change speed transmission was directly connected to a rear axle through a longitudinal propshaft. The production of new designs of change speed transmission for such conventional drive arrangements is becoming increasingly rare as change speed transmissions are designed and developed for the large numbers of vehicles now produced with transverse engines. Therefore, the change speed transmission used in the power train in accordance with the invention preferably includes a casing, rotary drive components and selector components substantially identical to those produced for a change speed transmission used in a front wheel drive motor vehicle where the change speed transmission has a drive input shaft and a drive output shaft extending from the same end of the change speed transmission, the change speed transmission having been modified to position the drive input shaft at the opposite end to the drive output shaft for receiving drive from the input propshaft. Such an arrangement is particularly advantageous as a known type of front wheel drive change speed transmission can be used and modified to position its drive input shaft at the opposite end from that for which the transmission was designed. In practice, such a modification is fairly straightforward as it will leave the internal selector components and gear trains unchanged thereby minimising the cost of the change speed transmission.
Preferably, the transfer gearing is positioned substantially midway between the front and rear differentials. In that way, the front and rear propshafts can be made of substantially equal length.
Also novel and according to another aspect of the invention is a motor vehicle which incorporates a power train according to said one aspect of the invention. In such a motor vehicle, the change speed transmission can be housed partly within a tunnel formed in a floor of the motor vehicle in which it is installed. In such a case, we prefer that the tunnel projects upwardly into the interior of the vehicle between foot wells for front and rear passengers so as not to intrude into either of the foot wells.


REFERENCES:
patent: 2904905 (1959-09-01), Armington
patent: 3073405 (1963-01-01), Hill et al.
patent: 4381828 (1983-05-01), Lunn et al.
patent: 4538700 (1985-09-01), Suzuki
patent: 4805720 (1989-02-01), Clenet
patent: 5010975 (1991-04-01), Sommer
patent: 5065835 (1991-11-01), Richter et al.
patent: 5209321 (1993-05-01), Sado
patent: 2695880 (1994-03-01), None
patent: 476619 (1937-12-01), None
patent: 453838 (1996-09-01), None
Patent Abstracts of Japan, vol. 009, No. 215 (M-409 , Sep. 3, 1985 and JP 60 076422 A (Iseki Noki KK), Apr. 30, 1985.

Affiliated with

Also associated with

Rating

Motor vehicle power train does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Motor vehicle power train, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor vehicle power train will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2489517