Drive Pinion Preload Nut Assembly for Independent Bearing Setting

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Solution Overview

Problem

Existing axle assemblies face challenges in accurately setting and maintaining bearing preload forces independently of yoke installation, which can affect the integrity of the seal and bearing performance.

Innovation Solution

The axle assembly incorporates a preload nut with a threaded portion that mates with the drive pinion shaft, a seal assembly that encircles the preload nut and extends to the differential carrier, and retaining features on the yoke to inhibit movement, allowing for independent setting of bearing preload forces and ensuring sealing integrity regardless of yoke installation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the preload nut is integrated with the yoke assembly, then the bearing preload can be set during yoke installation, but the seal assembly integrity is compromised and bearing performance is affected

Engineering Contradiction:
Improvebearing preload settingVSAvoidseal assembly integrity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention separates the preload nut from the yoke assembly into independent components. The preload nut threads onto the drive pinion shaft independently, allowing bearing preload to be set separately from yoke installation. This segmentation prevents the seal assembly from being compromised during preload adjustment, as the seal remains intact between the differential carrier and yoke while the preload nut operates independently on the shaft.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the preload nut is separated from the yoke assembly, then the seal assembly integrity is maintained, but the complexity of assembly increases

Engineering Contradiction:
Improveseal assembly integrityVSAvoidassembly structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

While the preload nut is separated from the yoke assembly, the invention merges the preload adjustment function directly into the drive pinion shaft through threaded portions. This integration of the preload mechanism into the existing shaft structure, rather than adding separate complex adjustment mechanisms, maintains simplicity while preserving seal assembly integrity.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If the seal assembly extends to the yoke, then sealing coverage is maximized, but the preload force setting is affected by yoke installation variations

Engineering Contradiction:
Improvesealing coverageVSAvoidpreload force accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The invention extracts the preload force application point from the yoke assembly interface and relocates it to the drive pinion shaft through the threaded preload nut. This allows the seal assembly to extend to the yoke for maximum sealing coverage while the preload force is independently controlled through the shaft threads, eliminating the coupling between yoke installation variations and preload force accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enables precise and accurate setting of bearing preload forces without affecting the seal assembly, enhancing the durability and reliability of the axle assembly by decoupling the preload force from yoke installation and ensuring consistent sealing performance.

Implementation Method 1

The preload nut has a thread that mates with the threaded portion of the shaft

Methodology Applied
Scientific EffectThreading engagement: Screw

Implementation Method 2

The seal assembly encircles the preload nut. The seal assembly extends from the preload nut to the differential carrier

Methodology Applied
Scientific EffectSealing: Semipermeable Membrane

Implementation Method 3

The bearing assembly encircles the shaft and rotatably supports the drive pinion on the differential carrier

Methodology Applied
Scientific EffectRolling contact: Ball Bearing

Data Source

PatentEP4407212A1Axle assembly having a drive pinion and a preload nut
Publication Date: 2024.07.31 ARVINMERITOR TECHNOLOGY LLC
  • EP4407212A1 patent drawingFigure 1
  • EP4407212A1 patent drawingFigure 2
  • EP4407212A1 patent drawingFigure 3

AI summary

An axle assembly having a differential carrier, a drive pinion, a bearing assembly, and a preload nut. The drive pinion has a shaft that has a threaded portion. The bearing assembly rotatably supports the drive pinion on the differential carrier. The preload nut mates with the threaded portion and exerts a preload force on the bearing assembly.