GB2031077A

GB2031077A - Differential gearing

Info

Publication number: GB2031077A
Application number: GB7931783A
Authority: GB
Original assignee: Loehr and Bromkamp GmbH
Current assignee: GKN Driveline Deutschland GmbH
Priority date: 1978-09-14
Filing date: 1979-09-13
Publication date: 1980-04-16
Also published as: JPS5540376A; IT7905211A0; IT7907045U1; FR2436293A1; GB2031077B; DE2839922A1; IT7907045V0

Abstract

A differential gear system comprises first (13) and second (14) rotatable elements, means (11 and 12) such as intermeshing spur gears for transmitting torque between the rotatable elements and means in the form of a carrier part (8) for moving at least one of the rotatable elements (13 and 14) along an orbital path, the centre of which is spaced from the axis about which said element is rotatable. The carrier part (8) may comprise a spur gear, the rotatable elements being mounted in bores provided in the spur gear, the rotatable elements (13 and 14) are provided with constant velocity ratio universal joints (18) at their outer ends which joints are adapted for plunging movement of respective output shafts (3) and being so mounted on the rotatable elements that the joint centre (32) always remains coincident with the rotational axis of the carrier part (8). <IMAGE>

Description

SPECIFICATION A differential gear system The present invention relates to a differential gear system particularly but not exclusively for use in a motor vehicle and is of the type having a drive input and a pair of differential output elements.

It is an object of the present invention to provide a differential gear system of a design which enables low cost production.

According to the present invention we provide a differential gear system comprising a carrier part which carries first and second rotatable elements having means for transmitting torque between the elements, the carrier part being rotatable about an axis to move at least one of the rotatable elements along an orbital path the centre of which is spaced from the axis about which said rotatable element is itself rotatable each rotatable element carrying a constant velocity ratio universal joint having members which are adapted to permit relative plunging movement, each joint being mounted on a respective rotatable element such that the joint centre is always coincident with the axis of rotation of the carrier part.

Preferably, the means for transmitting torque between the rotatable elements comprising intermeshing gears and conveniently a gear provided on one of the rotatable elements meshes with a gear provided on the other rotatable element.

Preferably, said gears are spur gears.

The carrier part may be provided with externally arranged gear teeth by means of which it is rotated through connection to a further rotating gear.

The gear assembly of the present invention has the advantage over the bevel gear equipped differential gear systems in that at least one gear less can be used and also the gears used are less expensive and more simple to manufacture compared with differential gear systems through which torque transmission takes place via spur gears, in this case at least two gears less can be used.

It is advantageous that it is easily possible to arrange both the rotational axes of the rotatable elements at a distance from the axis of rotation of the carrier part, a preferred embodiment being one in which the rotational axes of the rotatable elements are arranged on different sides of the axis of rotation of the carrier part.

To enable the centre of each constant veloc ity ratio universal joint to remain coincident with the axis of rotation of the carrier part the rotatable elements are mounted in the carrier part their rotational axes are inclined to the axis of rotation of the carrier part.

An advantage of the differential gear system of the present invention is that when used in a motor vehicle having independent suspension, the universal joint shafts between the driven wheels and the differential gear system are included in the differential gear assembly.

In this way, the differential gear transmission can be simplified so that only two differential spur gears are required.

The carrier part may be mounted for rotation in a housing the arrangement being such that the rotational axis of the rotatable elements and that of the carrier part intersect each other outside the housing the intersection taking place at the centre of the constant velocity ratio universal joint provided on each of the rotatable elements.

The arrangement can be modified to the extent that the angular inclinations of the axes of the rotatable elements, having the gears mounted thereon, or the distances of the rotatable elements from the carrier part rotational axis, are different from each other without imparting the function of the differential gear system.

The invention will now be described in more detail by way of example only with reference to the accompanying drawings, wherein: Figure 1 is a part sectional view of a differential gear system arranged in a vehicle; Figure 2 is a detailed part sectional view of another embodiment of the differential gear system; Figure 3 is a sectional view along the line 1-1 shown in Fig. 2; showing only the carrier part and rotatable elements mounted therein; The arrangement shown in Fig. 1 comprises a differential gear system 1 connected to constant velocity ratio universal joints 2 which drive car wheels 5 through drive shafts 3 and further universal joints 4. In this Figure the wheel suspension 6 is only schematically indicated.

The differential gear system 1 is connected to the motor vehicles engine by a spur-type driving gear 7 through a manual or automatic gear box (not shown). From the driving gear 7 torque is transmitted to a carrier part in the form of a main gear 8. The main gear 8 is arranged in a bearing 9 provided within hous ing 10. In a cavity of the main gear 8 are arranged first and second rotatable elements in the form of shafts 1 3 and 14 intercon nected by spur gears 11 and 1 2 which inter mesh with each other. The shafts 1 3 and 1 4 are provided with constant velocity ratio universal joints 2 at their outer ends.

Referring now to Fig. 2 a differential gear system 1 is shown on an enlarged scale. The main gear 8 is mounted in bearings 9 pro vided in the housing 10. The main gear 8 is a spur gear having teeth 1 5 which mesh with the teeth of the driving gear 7.

Differential gears 11 and 1 2 and their driv en shafts 1 3 and 14 are so arranged in bores in the main gear 8 that their central axes 24 and 25 about which they may rotate are at an angular inclination to the axis of rotation 26 of the main gear 8.

Constant velocity ratio universal joints 2 are connected to the driven shafts 1 3 and 1 4 in such a way that the joint centre 32 coincides with the intersection of the central axes of the driven shafts 13 and 14 and the axis of rotation 26 of the main gear 8.

Each joint 2 carries out a cone-like peripheral motion so that no additional kinematics based angular changes have to be made by the driving shaft 3.

The constant velocity ratio universal joints 2 are of the type in which the centre of the joint, which centre is defined by the axis of the outer joint member and a fixed position determined by the cage and the steering member of the joint, in the event of relative axial movement between the inner and outer joint members remains stationery relative to the driven shafts 1 3 or 14 and thus coincident with the axis of the rotation of the main gear 8. Such a joint is described in greater detail in British Patent Specification No.

1,384,734.

A sealing boot 23 is provided for sealing the interior of the joint to prevent the ingress of dirt and prevent escape of lubricant. The sealing boot 23 is attached to the housing 10 and therefore does not revolve with the drive shaft 3 at the other end of the sealing boot being provided with a bearing 33.

The differential gear assembly enables the use of telescopically adjustable drive shafts to he used between the joint attached to the rotatable elements and a universal joint attached to the wheel or other driven member.

Referring now to Fig. 3 which is a sectional view of the main gear and rotatable elements only aong the line 1-1 shown in Fig. 2. The main gear 8 which is provided with spur-type teth 15 supports both the rotatable elements comprising driven shafts t3 and 14 and respective differential gears 11 and 12 in bores formed therein.

The central axes 24 and 25 of the driven shafts 13 and 14 are spaced apart by an amount such that the differential gears 11 and 12 intermesh with each other.

The main gear 8 may be of a two part construction having an internal component 30 which is drivingly connected via keys 31 to the outer part of the main gear 8, which is equipped with spur teeth 1 5.

The differential gear assembly shown in Fig.

2 and Fig. 3 is, because of the arrangement of driven shafts 1 3 and 14 and the position and type of the constant velocity ratio universat joints 2, particularly suitable for high output speeds and hence particularly suitable for use in passenger motor vehicles.

Claims

1. A differential gear system comprising a carrier part which carries first and second rotatable elements having means for transmitting torque between the elements, the carrier part being rotatable about an axis to move at least one of the rotatable elements along an orbital path the centre of which is spaced from the axis about which said rotatable element is itself rotatable, each rotatable element carrying a constant velocity ratio universal joint having members which are adapted to permit relative plunging movement, each joint being mounted on a respective rotatable element such that the joint centre is always coincident with the axis of rotation of the carrier part.

2. A differential gear system as claimed in Claim 1 wherein the means for transmitting torque between the rotatable elements comprises a respective gear on each of the rotatable elements.

3. A differential gear system as claimed in Claim 2 wherein each of the rotatable elements is provided with a respective spur gear, which spur gears intermesh with each'other.

4. A differential gear system as claimed in Claim 3 wherein the respective axes about which said rotatable elements are mounted for rotation are both spaced from the rotational axis of the carrier part.

5. A differential gear system as claimed in Claim 4 wherein the axes of the rotatable elements are parallel to each other.

6. A differential gear system as claimed in Claim 4 wherein the axes of the rotatable elements are inclined at an angle to each other.

7. A differential gear system as claimed in Claim 4, wherein the axes of the rotatable elements are each spaced from the axis of rotation of the carrier part by an equal distance.

8. A differential gear system as claimed in any one of the preceding claims wherein said carrier part is formed as a spur-type gear.

9. A differential gear system as claimed in any one of the preceding claims wherein said carrier part is rotated through contact with a further spur gear driven by a prime mover.

10. A motor vehicle including a differential gear system as claimed in any one of the preceding claims.

11. A differential gear system substantially as hereinbefore described with reference to and as illustrated in Fig. 1 of the accompanying drawings.

1 2. A differential gear system substantially as hereinbefore described with reference to and as illustrated in Figs. 2 and 3 of the accompanying drawings.

1 3. A differential gear system including any novel feature or combination of features as described herein and/or illustrated in the accompanying drawings.