GB2054096A

GB2054096A - Drive assemblies

Info

Publication number: GB2054096A
Application number: GB7912839A
Authority: GB
Original assignee: PIV Antrieb Werner Reimers GmbH and Co KG
Current assignee: PIV Antrieb Werner Reimers GmbH and Co KG
Priority date: 1979-04-11
Filing date: 1979-04-11
Publication date: 1981-02-11
Also published as: DE3000298A1

Abstract

A final drive assembly particularly for a front wheel drive road vehicle has homokinetic universal joints 30 and 42 within the main housing of the assembly. One universal joint, 30, is within the carrier 13 of an otherwise conventional differential unit 12. The ends of the housing are closed by flexible elastomeric seals 32, 43 which incorporate rotary oil seals 34. <IMAGE>

Description

SPECIFICATION Drive assemblies The invention relates to drive assemblies incorporating torque transmitting universal joints and is particularly but not exclusively concerned with the final drive assembly for a motor vehicle incorporating a differential unit and drive shafts to the road wheels of the vehicle.

With a front wheel drive vehicle, it is desirable to make the drive shafts from the final drive unit to the wheel assemblies as long as possible in the interests of reducing the angles through which the joints have to drive as the geometry of the system varies with suspension and steering movements. With a fixed track between the two wheels governed by the width of the vehicle and with the normal outer universal joints mounted in the wheel hubs, any increase in length at the inner ends of the drive shafts would be particularly useful. Another relevant factor in some installations is that due to other constraints, the final drive unit may not be at the centre of the vehicle which would normally result in a requirement for unequal lengths of drive shafts. In this situation, any arrangement for increasing the length of the shorter drive shaft would be particularly useful.

There is also a tendency with some installations to require an increased length for the final drive assembly.

For example, instead of arranging only a differential unit and its associated final reduction gearing on the same axis, with certain transmission layouts it may be desirable to place the reverse gearing and some elements of a variable ratio gearing on the differential axis, thus tending to increase the axial length of the housing located between the drive shafts. Such an arrangement places further demands on providing the maximum available length for the drive shafts.

According to the present invention a drive assembly of the kind comprising: a housing, a driving member rotatable with respect to and positively located with respect to the housing and a driven shaft connected to the driving member by a torque transmitting universal joint which allows the direction of the driven shaft to be angled with respect to the driving member, is characterised in that the universal joint is positioned within the housing.

In a preferred form of the invention there is provided a drive assembly of the type comprising: a housing, a differential gearing incorporating a rotatable carrier, two output members rotatable with respect to and positively located with respect to the housing and bevel gears interconnecting carrier and output members, each output member forming a driving member for a driven shaft and a torque transmitting universal joint which allows the direction of the driven shaft to be angled with respect to the driving member; characterised in that at least one universal joint is positioned within the housing and within the carrier of the differential unit.

Preferably the carrier is supported in the housing in axially spaced bearings, one to either side of the universal joint.

Further in accordance with the invention there is provided a drive assembly of the kind comprising a housing, a driving member rotatable with respect and positively located with respect to the housing, a driven shaft connected to the driving member by a torque transmitting universal joint which allows the direction of the driven shaft to be angled with respect to the driving member, a seal to prevent egress of lubricant from the housing through the rotating drive and a flexible dust cover to protect the universal joint, characterised in that the universal joint is positioned within the housing and that a common flexible seal is used for the lubricant seal and the dust cover.

Preferably the seal is a flexible elastomeric seal fixed to the housing and with a rotatable sealing connection with the driven shaft.

Preferably the seal incorporates a rigid insert which carries a rotary lubricant seal engaged with the drive shaft.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawing which is a plan view, partially in section, of a drive assembly according to the invention.

A housing 11 incorporates the final drive elements of the transmission of a front wheel drive road vehicle. These elements may include an epicyclic final reduction drive, an epicyclic reversing gear and a driven element of a continuously variable ratio drive. These elements are not shown, because they form no part of the present invention. Their only significance to the invention is that they result in a housing 11 of substantial axial length, thereby reducing the length available for final drive shafts. The drive assembly also incorporates a differential unit 12.

The differential unit incorporates a carrier 1 3 which is mounted with respect to the housing 11 by means of an outer ball bearing 14 and an inner needle roller bearing 1 5. The carrier 13 is driven from other parts of the transmission which are not shown.

A radial shaft 1 6 is fixed in the carrier and also carries a pair of bevel gears 1 7 and 1 8. Bevel gears 1 7 and 18 mesh with further bevel gears 19 and 21 which are formed on output members 22 and 23 respectively of the differential unit. The differential unit operates in an entirely conventional manner to enable it to transmit drive at different speeds to the two output members 22 and 23.

The carrier 1 3 is also provided with a speedometer worm drive gear 20.

Differential output member 23 is welded directly to the outer member 24 of a homokinetic torque transmitting universal joint 30 of the kind described in U.K. Patent Specification 1,072,144.

Details of the joint will be described only briefly because these are well known from the above patent specification and extensive commercial use. Briefly, the universal joint incorporates the outer member 24, an inner member 25 and a series of balls 26 arranged in longitudinal grooves 27 and 28 in the outer and inner members respectively. The balls are retained in an appropriate planar aligment by means of a cage 29. The balls 26 transmit drive from the outer member 24 to the inner member 25, whilst allowing angular movement of the axis of an output shaft 31 formed integrally with the output member 25 and also allowing limited axial movement of this shaft.

It should be observed that the universal joint 30 is arranged within the housing 11 and also within the carrier 1 3 within which the outer member 24 is supported for rotation. The universal joint lies between the bearings 14 and 1 5 so that it is very close to the bevel gears of the differential unit.

This location of the universal joint is much nearer to the centre of the differential unit than is normally possible, thereby facilitating a lengthening of the drive shaft 31.

The components within the housing 11, including the differential unit 12, require extensive lubrication so a lubricant seal is required at the end of the housing. This is provided by a flexible elastomeric seal 32 which is secured to the end of the housing 11 by means of a strap 33. The seal 32 is convoluted in the usual way to provide substantial flexibility. In order to allow rotation of the shaft 31, a rotatable sealing connection is required between the seal 32 and the shaft 31.

The rotatable sealing arrangement incorporates a rigid annular insert 3 carried by the flexible seal 32 and a conventional rotary oil seal 34 supported in the insert 33 and bearing against the surface of shaft 31. A wiper lip 35 protects the rotating seal 34 against dirt from the outside.

With this arrangement, the whole of the universal joint is incorporated within the space which is lubricated by the main transmission lubrication system and this provides very effective lubrication for the universal joint.

Output member 22 from the differential unit drives a shaft 41, which passes through the housing to its opposite end of the housing and carries a further universal joint 42 corresponding to the universal joint 30. This universal joint is arranged just within an end portion of the housing 11. A seal 43, corresponding to. the seal 32, is arranged between the housing and an output shaft 44 which corresponds to the output shaft 31. The amount of length saved by the positioning of universal joint 42 within the housing 11 is less than the corresponding saving with the joint 30, but there is still a useful saving in length. A flange corresponding to but possibly slightly shorter than the flange 40 would still be required to house an oil seal for the shaft 41 and this would require displacement of the universal joint in an outward direction.

Claims

1. A drive assembly comprising: a housing, a driving member rotatable with respect to and positively located with respect to the housing and a driven shaft connected to the driving member by a torque transmitting universal joint which allows the direction of the driven shaft to be angled with respect to the driving member, characterised in that the universal joint is positioned within the housing.

2. A drive assembly comprising: a housing; a differential gearing incorporating a rotatable carrier, two output members rotatable with respect to and positively located with respect to the housing and bevel gears interconnecting carrier and output members, each output member forming a driving member for a driven shaft and a torque transmitting universal joint which allows the direction of the driven shaft to be angled with respect to the driving member; characterised in that at least one universal joint is positioned within the housing and within the carrier of the differential unit.

3. A drive assembly according to claim 2 wherein the carrier is supported in the housing in axially spaced bearings, one to either side of the universal joint.

4. A drive assembly comprising a housing, a driving member rotatable with respect and positively located with respect to the housing, a driven shaft connected to the driving member by a torque transmitting universal joint which allows the direction of the driven shaft to be angled with respect to the driving member, a seal to prevent egress of lubricant from the housing through the rotating drive and a flexible dust cover to protect the universal joint, characterised in that the universal joint is positioned within the housing and that a common flexible seal is used for the lubricant seal and the dust cover.

5. A drive assembly according to claim 4 wherein the seal is a flexible elastomeric seal fixed to the housing and with a rotatable sealing connection with the driven shaft.

6. A drive assembly according to claim 5 wherein the seal incorporates a rigid insert which carries a rotary lubricant seal engaged with the drive shaft.