Vehicle differential and method

• US 6,736,544 B1
• Filed: 05/31/2002
• Issued: 05/18/2004
• Est. Priority Date: 05/31/2002
• Status: Expired due to Term

• Current Assignee: Dana Heavy Vehicle Systems Group LLC (Dana, Inc.)
• Original Assignee: Dana Corporation (Dana, Inc.)
• Inventors: DeWald, Gregory T.
• Primary Examiner(s): Hannon, Thomas R.
• Application Number:
  US10/160,457
• Time in Patent Office: 718 Days
• Field of Search: 384/626, 384/584, 384/585, 384/583, 384/559, 384/562, 298/980.6, 298/980.7, 298/980.9
• US Class Current: 384/626
• CPC Class Codes: F16C 19/364 with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
• CPC Class Codes: F16C 19/548 in O-arrangement
• CPC Class Codes: F16C 19/56 in which the rolling bodies of one bearing differ in diameter from those of another
• CPC Class Codes: F16C 2229/00 Setting preload
• CPC Class Codes: F16C 2361/61 Toothed gear systems, e.g. support of pinion shafts
• CPC Class Codes: F16C 25/06 Ball or roller bearings
• CPC Class Codes: F16H 2048/385 of the ring or crown gear
• CPC Class Codes: F16H 2048/423 characterised by bearing arrangement
• CPC Class Codes: F16H 2057/0221 Axial adjustment
• CPC Class Codes: F16H 2057/0227 Assembly method measuring first tolerances or position and selecting mating parts accordingly, e.g. special sized shims for transmission bearings
• CPC Class Codes: F16H 48/42 characterised by features of the input shafts, e.g. mounting of drive gears thereon
• CPC Class Codes: F16H 57/021 Shaft support structures, e.g. partition walls, bearing eyes, casing walls or covers with bearings
• CPC Class Codes: F16H 57/037 Gearboxes for accommodating differential gearings rotating cases for differential gearings F16H48/40
• CPC Class Codes: Y10T 29/497 Pre-usage process, e.g., preloading, aligning

Abstract

An improved method and structure for setting pinion bearing preload and fastener clamp load in a vehicle differential is provided. The apparatus and method provide a preload spacer readily accessible outboard of the pinion bearings and input yoke. Pinion bearing preload is set according to the present invention by the force of the pinion gear on the inner cone of an inner bearing and the force of an input yoke on the outer cone of an outer bearing. As a nut is torqued into contact with the input yoke, a preload spacer limits the movement of the nut as the input yoke engages the outer cone. This provides for consistent preload on the bearings and allows for increased clamp load for retaining the nut.

Claims

1. A differential, comprising:

a housing;

an inner bearing having an inner cup mounted within the housing and supporting an inner cone assembly;

an outer bearing having an outer cup mounted within the housing and supporting an outer cone assembly;

a pinion drive shaft having a shaft supported by the inner cone assembly and outer cone assembly, a pinion gear at a first end of the shaft in engagement with the inner cone assembly, and a shank extending from a shoulder at a second end of the shaft;

an input yoke coupled to the second end of the shaft between the outer cone assembly and the shank and in engagement with the outer cone assembly;

a nut disposed about the shank and in engagement with the input yoke; and

a preload spacer disposed between the nut and the shoulder outboard of the outer bearing; and

wherein the preload spacer limits the relative movement between the input yoke and pinion drive shaft, limiting the force of the input yoke on the outer cone assembly and the pinion gear on the inner cone assembly and allowing increased clamp load between the shank and nut.

2. The differential of claim 1, the housing further comprising:

an inner radial wall;

an outer radial wall; and

wherein the inner radial wall and outer radial wall retain the inner cup and outer cup in fixed axial relation to the housing when the preload forces are applied.

3. The differential of claim 1, wherein the preload spacer is adapted to withstand high axial loads.

4. The differential of claim 1, further comprising:

the outer bearing having a measured height; and

the preload spacer forming a matched set with said outer bearing and having a height defined in part by the outer bearing set measured height.

5. A method of controlling pinion bearing preload in a differential, comprising:

press fitting an inner cup and an outer cup within a housing;

press fitting an inner cone assembly and an outer cone assembly about a shaft of a pinion drive shaft;

supporting the inner cone assembly within the inner cup and the outer cone assembly within the outer cup with a pinion gear at a first end of the shaft in contact with the inner cone assembly and with a shank and shoulder at a second end of the shaft extending outboard of the outer cone assembly;

press fitting a bearing seal retainer in the housing including a seal;

coupling an input yoke to the second end of the pinion drive shaft between the outer cone assembly and the shank putting the input yoke in contact with the outer cone assembly;

installing a preload spacer about the shank and against the shoulder of the shaft; and

torquing a nut about the shank into engagement with the input yoke and the preload spacer to achieve the corresponding pinion bearing preload condition and continuing to apply torque until reaching the desired clamp load between the nut and shank.

6. The method of claim 5, further comprising adjusting the forces acting on the inner cone assembly and outer cone assembly by:

removing the nut from the shank;

replacing the preload spacer with a preload spacer having a different height; and

retorquing the nut about the shank.

7. The method of claim 5, wherein press fitting the inner cup and outer cup within the housing comprises:

mounting the inner cup in engagement with an inboard side of an inner radial wall of the housing and mounting the outer cup in engagement with an outboard side of an outer radial wall of the housing.

8. The method of claim 5, further comprising the following method for selecting a height H′

for the preload spacer;

providing a master outer cup having a mean height and a master outer cone having a mean height;

mounting an inner cup within a housing with a press fit and mounting an outer cup within the housing with a press fit;

press fitting an inner cone assembly about a shaft of a pinion drive shaft, installing the pinion drive shaft and inner cone assembly into the housing, and mounting the master outer cone assembly about the shaft of the pinion drive shaft with a slip fit, the a pinion gear at a first end of the shaft in contact with the inner cone assembly and with the shank and shoulder at a second end of the shaft extending outboard of the master outer cone assembly;

coupling an input yoke to the second end of the pinion drive shaft between the outer cone assembly and the shank putting the input yoke in contact with the outer cone assembly;

engaging a preloading tool into engagement with the input yoke until reaching a specified clamp load corresponding to a desired pinion bearing preload condition and measuring the corresponding distance A between the portion of preloading tool in contact with the input yoke and the shoulder of the pinion drive shaft;

measuring the difference B between the height of the master outer cone assembly and an outer cone assembly;

choosing a constant K to account for elasticity of the components; and

determining the height H′

of the preload spacer to by combining the value A and the value B and the value K.

9. The method of claim 8, further comprising:

removing the preloading tool, input yoke, and master outer cone assembly and press fitting the outer cone assembly onto the shaft.

10. The method of claim 5, wherein engaging the preloading tool comprises:

assembling an outer piece into engagement with the input yoke and an inner piece into engagement with the shoulder and applying an axial force to the input yoke until reaching a specified clamp load of 1000 lbs corresponding to a desired pinion bearing preload condition and measuring the corresponding distance A between the end of the preloading tool in contact with the input yoke and the shoulder of the pinion drive shaft.