GB2035235A - Motor vehicles - Google Patents

Abstract

A motor vehicle having a chassis in which is mounted a prime mover 10 and a casing 14 of a driven axle unit 11 has the casing 14 and the prime mover 10 connected by a torsionally resistant hinge joint 23. Road wheels, which are mounted on the vehicle chassis by suspension, are driven by universally jointed shafts from the axle casing. The hinge joint 23 may be replaced by a torsionally resistant flexible tubular bellows. <IMAGE>

Description

SPECIFICATION Motor vehicles This invention relates to motor vehicles of the type, hereinafter referred to as being of the type described, having a chassis, a prime mover mounted in the chassis and at least one driven axle having a casing mounted on the chassis and comprising means for transmitting power from an input shaft extending longitudinally of the chassis to output shafts extending transversely of the chassis and connected to road wheels suspended from the chassis.

Various arrangements have been proposed hitherto for interconnection of prime mover and axle casings in a motor vehicle. For example, a rigid casing of tubular form has been proposed, for resisting torque between the units. However, bending loads as well as torques are involved in such an application, and, particularly for heavy commercial vehicles, any such rigid structure would have to be impractically massive to resist such forces. It is the object of the present invention to provide an improved connection between prime mover and axle casing.

According to the invention we provide a motor vehicle of the type described in which the prime mover and the axle casing are interconnected by a torsionally resistant flexible joint.

The joint may be a pivoted joint providing for pivotal movement about an axis extending transversely of the vehicle. This will allow relative pitch between the axle casing and prime mover but resist all other relative movement. The axis about which pitch can occur must pass through the bending centre of a universal joint incorporated in the shaft by which power is transmitted from the prime mover to the axle, to avoid the necessity of providing a splined connection or the like in the shaft. Such a connection would be necessary to accommodate length variations which would occur if the pivotal axis did not pass through the centre of the joint.

Alternatively the joint may be in the form of a tubular bellows. Such a joint will resist torsion so that the prime mover and axle casing will be torsionally connected but will permit the relative pitching action between the prime mover and the axle casing.

By providing a torsionally resistant flexible joint between the prime mover and the axle casing it is not necessary to provide a conventional form of propeller shaft between the prime mover and the casing. Such a propeller shaft would normally incorporate at least two universal joints and a sliding splined connection to accommodate changes in the distance between the casing and the prime mover if the casing were mounted on springs. However, by having the axle casing chassis-mounted it is only necessary to provide between the axle casing and the prime mover a shaft with a single universal joint.

The vehicle may comprise two or more driven axles which have casings as described above, the casings being rigidly connected together and the combined casing mounted on the chassis.

Thus the vehicle may have an axle unit comprising at least two adjacent driven axles each comprising a casing mounted on the vehicle chassis and containing means providing for power transmission for an input shaft to output shaft extending generally transversely of the vehicle to road wheels mounted on the vehicle chassis by suspension means, the input shaft of one of the axles being connected to the rotary output of the prime mover, the casing of that axle being connected to the prime mover through a torsionally resistant coupling and the input shaft of the other axle being connected to a further output shaft of the first axle, the axle casings being rigidly connected together by means other than the vehicle chassis on which they are mounted, a driving connection between the two casings being provided by a rigid shaft.

The invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which Figure l is a perspective view of part of a prime mover and axle arrangement for a motor vehicle embodying the invention; and Figure 2 is a side elevation of the arrangement of Figure 1.

Referring to the drawings, there is illustrated a prime mover comprising an engine, clutch, and gearbox unit 10, and two drive axle units 11, 12 arranged in tandem and forming part of a tandemaxle assembly. The unit 11 has a casing 14 which contains a first differential gearing drivable from an input shaft 13 and providing for output of two parallel shafts 15, 16 which in the vehicle are connected by drive shafts incorporating universal joints to road wheels 29 supported from the vehicle chassis by suspension means. The unit 11 also contains a second differential gearing operative between the shaft 13 and a further output shaft 17 which is connected to the input of the unit 12. The unit 12 contains, within a casing 21, a single differential gearing by which output shafts 18, 19to further road wheels can be driven.

The casings 14, 21 of the final drive units are rigidly connected by a tube 22 which encloses the shaft 17. Casing 14 and the engine unit 10 are connected by a torsionally resistant joint which includes a hinge 23 providing for relative angular movement of the units 10 and 11 about a horizontal transverse axis 24. By virtue of these connections, the shaft 17 need not incorporate any universal joints or sliding spline connections, and the shaft 13 can be connected to the rotary output of the prime mover engine unit 10 by a single universal joint 25.

The axis 24 passes through the bending centre of joint 25 so that no spline connection or like provision for length variation is necessary in shaft 13.

When mounted in a vehicle, the interconnected units are supported on the vehicle chassis (shown diagrammatically at 30) by a main mounting 26 at the centre of gravity of the connected final drive units 11, 12 and a mounting 27 at the centre of gravity of the engine-gearbox-clutch unit 10. A mounting 28 at the rear of the unit 10 supports the forward end of the assembly of final drive units 11, 12 and stabilizes both assemblies in pitch. An economy is effected compared with the number of mountings which would be necessary were all the units to be individually mounted to the chassis of the vehicle, and, in addition, complex universally jointed and sliding spline connections in the shafts interconnecting the units are avoided.

The hinged connection 23 between the enginegearbox-unit and final drive units permits relative pitch between these units, but absorbs torque reaction therebetween so that the mountings thereof do not have to resist this. This hinged connection may be replaced by a tubular bellows interconnecting the units 10 and 14 or by a connection having co-operating elements in the manner of the type of torque-transmitting universal joint known as a tripode joint.

Although the invention has been described using a tandem axle, the second axle unit 12 could be omitted. By virtue of the rigid interconnection of the casings 14 and 21 of the two axle units, a universally jointed shaft between the axle units is not necessary and torque reactions arising in service are taken by the mounting of the axle units considered as a whole rather than separately.

Claims (6)

1. A motor vehicle comprising a chassis, a prime mover mounted in the chassis, at least one driven axle having a casing mounted on the chassis and comprising means for transmitting power from an input shaft extending longitudinaly of the chassis to output shafts extending transversely of the chassis, and road wheels suspended from the chassis and connected to said output shafts, and a torsionally resistant flexible joint interconnecting the prime mover and axle casing.

2. A motor vehicle according to claim 1, wherein said torsionally resistant flexible joint includes pivot means providing for relative pivotal movement about a single axis extending transversely of the vehicle, said input shaft incorporating a universal joint and said axis passing through the bending centre of such joint.

3. A motor vehicle according to claim 1 wherein said torsionally resistant flexible joint provides for universal pivoting between said prime mover and axle casing.

4. A vehicle according to any one of the preceding claims, comprising at least two driven axles each having a casing, said casings being rigidly connected together and mounted on the chassis as a unit.

5. A vehicle according to any one of the preceding claims, wherein said flexible joint partially supports said axle casing.

6. Avehicle substantially as hereinbefore described with reference to and as shown in the accompanying drawings.