GB2192957A

GB2192957A - Differential gear assembly with two part housing and lubricating oil gallery

Info

Publication number: GB2192957A
Application number: GB08709232A
Authority: GB
Inventors: Michael William Arrindell; Robert Andrew Rickell
Original assignee: GKN Axles Ltd
Current assignee: Dana Spicer Europe Ltd
Priority date: 1986-04-19
Filing date: 1987-04-16
Publication date: 1988-01-27
Also published as: GB8709232D0; GB2192957B; GB8609615D0

Abstract

The assembly comprises a two part casing (10, 11), a differential carrier (13) mounted in the casing by roller bearings (21 22) whose outer races are received in mating pairs of recesses (as 23, 24) in the casing parts, and a lubricating oil gallery formed as part of the casing and having a central part (46) arranged to receive lubricating oil thrown up by the carrier or crown wheel secured thereto when rotating and side parts (47) leading the received oil to the mating recesses in casing. Opening 49 in the recesses lead the oil to the outer ends of the bearings 21, 22 from which the oil can pass back through the bearings to lubricate them. <IMAGE>

Description

SPECIFICATION Differential gear assembly This invention relates to differential gear assemblies for motor vehicles.

It is known to have a differential gear assembly comprising a two part casing in which the differential carrier is mounted in bearings which. are received in pairs of mating recesses in the casing and mounted on spigots on the carrier.

The casing provides a sump for lubricating oil but since the outer ends of the bearings are outside the casing there is difficulty in ensuring that the bearings are adequately lubricated. Normally the bearings will be roller thrust bearings and will tend to pump any lubricating oil from the outside of the casing inwards so that one cannot rely on splash lubrication as one could were the bearings mounted within the casing entirely rather than in the walls of the casing.

An object of the invention is to provide a differential gear assembly having a casing as described in which means is provided for positively lubricating the carrier bearings.

According to the invention we provide a differential gear assembly comprising a two-part casing providing a sump for lubricating oil, a differential gear carrier rotatably mounted in said casing by roller bearings whose outer races are received in mating pairs of recesses in the casing parts and whose inner races are received on spigots of the carrier, a lubricating oil gallery provided as part of the casing, the gallery having a central part arranged to receive lubricating oil thrown up by the carrier and/or a crown wheel secured thereto when the assembly is in operation and the gallery having side parts to lead the received oil to the pairs of mating recesses, openings in said recesses external to said outer races so as to lead the oil to the outer ends of the bearings and housings secured to the casing outside the bearings to support drive shafts engagable with the carrier.

In a differential gear assembly according to the invention, the formation of the oil gallery as part of the casing (e.g. by providing it in the casing in manufacture thereof in a casting process) means that it is not necessary to provide separate parts within the casing to direct oil to the carrier bearings. In addition to the additional production processes which would be involved if such separate parts were provided, there would always be the risk of such parts becoming detached in use and possibly causing damage.

Preferably each housing has a spigot which is received in a pair of mating recesses, and which engages the outer race of the bearing received therein, the spigot having a radially extending slot which aligns with the respective opening in said mating recesses, to allow the lubricating oil from the gallery to pass to the outer ends of the bearings. In manufacturing terms, it is relatively easy to provide the mating recesses with openings, e.g. slots which may be milled or possibly formed in the casing during manufacture thereof by casting, and to provide the spigots with slots. Drilling the casing or other parts to provide oil passages is avoided.

The oil which is delivered to the outer ends of the bearings is preferably delivered to an annular chamber defined around the respective drive shaft, between the respective bearing and an oil seal carried by the housing. As well as lubrication of the bearing, lubrication of the drive shaft where it engages the carrier, and the oil seal, is ensured.

The invention will now be described in detail by way of example with reference to the accompanying drawings in which: Figure 1 is a section through a differential gear assembly embodying the invention; Figure 2 is a partial sectional view on the line ll-ll of Figure 1; and Figure 3 is a scrap view on the line Ill-Ill of Figure 2.

Referring first to Figure 1, the differential assembly comprises a two part casing the parts of which are indicated at 10 and 11.

The parts meet in the plane of the line 12 perpendicular to the drawing.

The differential gear comprises the usual carrier 13 to which is bolted a crown wheel 14. The crown wheel meshes with a pinion 15 which is carried in pinion bearings 16 and 17 in the casing part 10. The pinion shaft carries a driving flange 18 and an oil seal 19 is provided.

The carrier 13 is mounted in roller thrust bearings 20 and 21 which are identically arranged and of which the bearing 20 will be described in detail. This bearing comprises an outer race 22 which is received in mating recesses 23 and 24 in the casing parts 10 and 11 respectively. The inner race 25 of the bearing is received on a spigot 26 on the carrier.

At each end of the casing is a housing, the housings being indicated at 27, 28 and being identical; the housing 27 will be described in detail. The housing is secured to the casing parts 10, 11 by a number of set pins, one of which is indicated at 29. The housing has a generally cylindrical body portion 30 and a spigot 3 1 which is received in the mating recesses 23 and 24. In a counterbore 32 in the housing is received a ball bearing assembly 33, the outer race of which is received in the counterbore and the inner race of which is mounted on a drive shaft 34. The bearing 33 is held in position by a circlip 35.

The housing carries an oil seal 36 which engages a collar 37 pressed on the drive shaft 34. The inner end of the drive shaft engages one of the side gears of the differen tial gear, not shown, which is within the carrier 13 and at the outer end of the drive shaft there is a driving flange 38.

Shims 39 are received between a flange 40 on the housing 27 and the casing.

By adjustment of the shims 39 between the housings 27 and 28 on the one hand and the casing on the other, the mesh between the crown wheel 14 and the pinion 15 can be adjusted. Thus by increasing the shims between the housing 28 and the casing for example and reducing the shims between the casing and the housing 27 the carrier 13 and the crown wheel 14 may be moved to the left. Once the desired position or mesh of the crown wheel and pinion has been obtained by adjusting the shims between the housings and the casing, a predetermined number of shims will then be removed from each position thus to provide a desired preload on the carrier bearings by loading the outer races 22 thereof.

The means for lubricating the carrier bearings will now be described with reference to Figures 2 and 3.

A lubricating oil gallery is formed in the casing part 10 as an integral part thereof and as indicated generally at 45. The gallery has a central portion 46 which collects oil which is thrown up from the bottom of the casing by the crown wheel 14 and/or the carrier 13.

The gallery has side portions 47 and 48 of channel shape which lead oil collected by the central portion 46 to the mating recesses 23 and 24. The mating recess 23 has a slot 49 therein which is external of the outer race 22 so that oil can then pass through this slot 49 and through a radially extending slot 50 formed in the spigot 3 1 which aligns with the slot 49. Oil is thus delivered to an annular chamber 51 surrounding the drive shaft 34, defined between the bearing 20 and the oil seal 36. Oil delivered to this chamber can then lubricate the oil seal 36 and the shaft 34 and having been supplied to the outer part of the bearings will be pumped by the bearings back into the casing. It will be seen, therefore, that a simple and effective oil supply system for the carrier bearings is provided.

Also visible in Figure 2 of the drawings is a passage 53 having an opening 54, positioned to receive oil thrown within the casing by the crown wheel 14 and/or carrier 13. Passage 53 delivers oil to an annular chamber 55 between the bearings 16, 17 carrying the pinion 15 in the casing part 10, for lubricating such bearings. A passage 56 provides for return to the casing of oil passing through the bearing 16, in generally known manner.

Figure 2 shows a flow of oil from the crown wheel into the gallery 46, 47 which is established by rotation of the crown wheel in the clockwise direction, with reference to Figure 2. Effective collection of oil by the gallery results from the arrangement that the gallery faces the periphery of the crown wheel in its normal direction of rotation, which will be when the vehicle to which the differential gear assembly is fitted is travelling forwards. If, however, the normal direction of operation of the gear assembly is one in which the crown wheel rotates anti-clockwise with regard to Figure 2, the gallery 46, 47 could equally well be provided in the casing part 11 instead of the casing part 10 as illustrated, so as to face the direction of normal peripheral movement of the crown wheel.

Claims

1. A differential gear assembly comprising a two-part casing providing a sump for lubricating oil, a differential gear carrier rotatably mounted in said casing by roller bearings whose outer races are received in mating pairs of recesses in the casing parts and whose inner races are received on spigots of the carrier, a lubricating oil gallery provided as part of the casing, the gallery having a central part arranged to receive lubricating oil thrown up by the carrier and/or a crown wheel secured thereto when the assembly is in operation and the gallery having side parts to lead the received oil to the pairs of mating recesses, openings in said recesses external to said outer races so as to lead the oil to the outer ends of the bearings, and housings secured to the casing outside the bearings to support drive shafts engagable with the carrier.

2. A differential gear assembly according to Claim 1 wherein each housing has a spigot which is received in a pair of mating recesses and engages the outer race of the bearing received therein, the spigot having a radially extending slot which aligns with the respective opening in said mating recesses, to allow the lubricating oil from the gallery to pass to the outer ends of the bearings.

3. A differential gear assembly according to Claim 1 or Claim 2 wherein at least the side parts of the gallery are of channel shape, and have been provided in the casing in manufacture thereof by casting.

4. A differential gear assembly according to Claim 2 wherein an annular chamber is defined around each said drive shaft, between the respective bearing and an oil seal carried by the respective housing.

5. A differential gear assembly according to any one of the preceding claims wherein said central part of the gallery faces the direction of normal peripheral movement of said carrier and/or crown wheel.

6. A differential gear assembly having means for lubricating the differential carrier bearings substantially as hereinbefore described with reference to the accompanying drawings.