WO2009084019A2

WO2009084019A2 - Improved differential assembly

Info

Publication number: WO2009084019A2
Application number: PCT/IN2008/000663
Authority: WO
Inventors: Anand Swichalappa Damami; Amit Suhas Barve; Prafulla Vijay Wankhede
Original assignee: Tata Motors Limited
Priority date: 2007-12-31
Filing date: 2008-10-13
Publication date: 2009-07-09
Also published as: ZA201004680B; WO2009084019A3

Abstract

This invention relates to a differential assembly comprising; a differential housing (1); a differential pinion gear assembly including a pinion shaft, said pinion gears drivingly engaging corresponding bevel gears (3) to provide differential rotation; a speed detect gear (6) is configured to be push-fitted onto the differential housing (1); wherein, said differential assembly is of open type, said pinion shaft is firmly located within the said housing by means of a spring dowel (5).

Description

IMPROVED DIFFERENTIAL ASSEMBLY

FIELD OF INVENTION

This invention relates to differential assembly of automobile and more particularly it relates to open type differential assembly with ease of manufacturing, minimum part count & provision of fixing of speed detect gear on differential.

BACKGROUND OF INVENTION

Differential is very much essential in all automobile on live axles which helps to maintain speed deferential between left & right side axle during cornering of the vehicle. Also it helps in torque multiplication because of final drive gear fixed on differential housing. Figure 1 shows conventional differential assembly which consists of close type differential housing (a), Final drive gear (b), bevel gear (c), bevel pinion (d), spider with two circlips (e) & speed detect gear (f). Wherein said bevel gear (c) and bevel pinion (d) are provided inside differential housing, said bevel pinion is located with spider with circlip (e). Said final drive gear (b) and speed detect gear (f) are press fitted on differential housing.

The conventional close type differential housing requires special tooling & machining operations during manufacturing which are costly.

The conventional differential design uses final drive gear which is annular in shape & has transient fit on housing. To fix the final drive gear on differential housing requires equipments & more time. Also it uses more No of parts to retain spider inside the differential. Considering the size of the circlips, assembly of circlips is time consuming.

The conventional speed detect gear is forged or machined toothed wheel which is to be press fitted on differential. This tooth wheel carries more material, manufacturing processes & special equipments for assembly.

OBJECTS OF INVENTION

> The main object of this invention is to provide improved differential design which calls for simple manufacturing process.

> Another object of this invention is to provide improved differential assembly with minimum number of parts.

> Yet another object of this invention is to provide improved differential assembly with speed detect gear which is simple in construction & cost effective.

BRIEF DESCRIPTION OF INVENTION

Improved differential assembly in accordance with this invention basically comprises of open type differential housing, final drive gear with support for bevel gears , spider with a provision for spring dowel, speed detect gear, bevel gears and bevel pinions . Wherein spigot of said final drive gear is precisely located inside said differential housing, said bevel gear and pinions are located with spider and spring dowel. Said speed detect gear is push fitted on said differential housing.

As the said differential housing is of open type, it is easy to manufacture the same. As differential housing and final drive gear are precision fitted the special equipments are not required to fit the said units. Said speed detect gear is made up of sheet metal which contributes drastically in weight reduction and makes the manufacturing process simple. Said speed detect gear can be easily fitted on said differential by simple readily available equipments.

STATEMENT OF INVENTION

Accordingly, the present invention discloses a differential assembly comprising: a differential housing; a differential pinion gear assembly including a pinion shaft, said pinion gears drivingly engaging corresponding bevel gears to provide differential rotation; a speed detect gear is configured to be push-fitted onto the differential housing; wherein, said differential assembly is of open type, said pinion shaft is firmly located within the said housing by means of a spring dowel.

BRIEF DESCRIPTION OF DRAWINGS

Fig.1 shows Conventional differential assembly

Fig.2 shows improved differential assembly in accordance with this invention

Fig.3 shows Open type differential housing used in this invention

Fig.4 shows Final Drive gear used in this invention

Fig.5 shows Spider used in this invention

Fig-6 shows Speed detect gear

DETAILED DESCRIPTION OF INVENTION

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same, Referring to figs. 2 to 6

Improved differential assembly in accordance with this invention basically comprises of open type differential housing (1), final drive gear with support for bevel gear (2) ,a pinion shaft or spider with a provision for spring dowel (5), speed detect gear (6), bevel gears (3) and bevel pinions (4) . Wherein spigot of said final drive gear is precisely located inside said differential housing (1), said bevel gear and pinions are located with spider and spring dowel (5). Said speed detect gear is push fitted on said differential housing.

As shown in the figure (3), Said open type differential housing comprises of spigot bore (7). The bore size is selected such a way that it makes manufacturing easy & helps in precision location fit of final drive gear. The speed detect gear holding diameter (8) is provided on a differential housing in such a way that speed detect gear can be easily press fitted on it. Said deferential housing is also provided with taper surface for sufficient grip of said speed detect gear on said surface.

As shown in the figure (4), said final drive gear with support for bevel gear comprises of cylindrical spigot (9) which supports bevel gear inside differential housing & maintains the symmetry of differential about spider axis. The outer diameter of spigot (10) is selected such a way that it maintains precision location fit with differential housing.

As shown in the figure (5), said spider has a cross hole (11) to carry spring dowel which arrest spider inside differential. As shown in the figure (6), said speed detect gear is made up of 1.25 mm thick sheet metal & saves extra material & cost. It carries bend lugs(12) to suit electronic speed sensor unit. The bore diameter (13) is designed such a way to achieve push fit.

"Open type differential housing". The major advantage of this is more accessibility to internal surfaces of the housing which makes it easy to manufacture." Final Drive gear "is designed such a way that it supports the bevel gear & maintains the symmetry about spider shaft." Final drive gear" has precision location fit with differential housing which eliminates special equipments like press to assemble final drive gear on differential. This design calls for "spring Dowell" to locate spider which eliminates two circlips. This reduces part count, complexity in assembly of two circlips & extra length of spider to hold circlips. "Sheet metal speed detects gear" is designed with specific tolerances & material that it can directly press fitted with differential housing with hand tools. This replaces forged/machined slotted wheel which has higher cost. Also It eliminates the special equipments like hydraulic press to assemble forged / machined wheel on differential housing.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

Claims

1. A differential assembly comprising: a differential housing; a differential pinion gear assembly including a pinion shaft, said pinion gears drivingly engaging corresponding bevel gears to provide differential rotation; a speed detect gear is configured to be push-fitted onto the differential housing; wherein, said differential assembly is of open type, said pinion shaft is firmly located within the said housing by means of a spring dowel.

2. The differential assembly as claimed in claim 1, wherein said open type differential housing comprises of spigot bore, the bore size being configured to facilitate precision location fit of final drive gear.

3. The differential assembly as claimed in claim 1, wherein said deferential housing is further provided with a taper surface for sufficient grip of said speed detect gear on said surface.

4. The differential assembly as claimed in claim 1, wherein said final drive gear in engagement with differential housing comprises of cylindrical spigot which supports the bevel gear inside said differential housing and maintains the symmetry of differential about said pinion shaft axis.

5. The differential assembly as claimed in claim 4, wherein the outer diameter of said spigot is selected such a way that it maintains precision location fit with differential housing.

6. The differential assembly as claimed in claim 1, wherein said pinion shaft or spider has a cross hole to carry spring dowel.

7. The differential assembly as claimed in claim 1, wherein said speed detect gear comprises lugs adapted to position an electronic speed sensor unit.

8. The differential assembly as claimed in claim 1, wherein said speed detect gear is made of sheet metal.

9. The differential assembly as claimed in claim 1, wherein said differential housing having holding diameter for push fit said speed detect gear.

10. A differential assembly as hereinabove mentioned with reference to the Figures 2 to 6.