Differential Assembly Interference Fit for Wear-Resistant Torque Transfer

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Solution Overview

Problem

Existing differential assemblies are prone to wear due to the transfer of torque between the gear wheel and differential cross, and they compromise ease of assembly for improved wear resistance.

Innovation Solution

A differential assembly design featuring a gear wheel with radially extending recesses and a differential cross engaging with these recesses via an interference fit, ensuring secure engagement and preventing wear during torque transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional differential assembly uses a simple connection between the gear wheel and differential cross, then ease of assembly is improved, but wear resistance deteriorates due to torque transfer causing wear between components

Engineering Contradiction:
Improveease of assemblyVSAvoidwear resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The connection interface is segmented into multiple radially extending recesses in the gear wheel that engage with corresponding protrusions on the differential cross arms. This segmentation distributes the torque transfer across multiple contact points, reducing wear at each individual interface while maintaining assembly simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection interface features localized interference fit regions where the radially extending recesses create specific contact zones with the differential cross arms. These localized high-quality contact regions provide enhanced wear resistance exactly where torque transfer occurs, while other portions of the components remain simple for manufacturing.

Inventive Principle:
Principle #3Local quality

2Reliability

If an interference fit is used between the differential cross and gear wheel, then wear resistance is improved, but assembly complexity increases

Engineering Contradiction:
Improvewear resistanceVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The interference fit is segmented into multiple discrete radially extending recesses rather than a continuous complex interface. This allows the interference fit to be achieved through simple radial alignment and pressing operations, reducing assembly complexity while maintaining the wear resistance benefits of interference fitting.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of making the differential cross fit into the gear wheel, the design inverts the approach by having radially extending recesses in the gear wheel that receive the differential cross arms. This inversion simplifies the assembly process by allowing straightforward radial insertion while still achieving the desired interference fit for wear resistance.

Inventive Principle:
Principle #13The other way round (Inversion)

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

The design provides resistance to wear and maintains torque transfer efficiency while allowing for a compact and robust assembly.

Implementation Method 1

each arm of the differential cross engages with one of the radially extending recesses via an interference fit

Methodology Applied
Scientific EffectInterference fit: Friction

Data Source

PatentEP4303467B1Differential assembly and vehicle and method for assembling differential assembly
Publication Date: 2026.01.28 TRATON AB
  • EP4303467B1 patent drawingFigure 1~2
  • EP4303467B1 patent drawingFigure 3a~3b
  • EP4303467B1 patent drawingFigure 3c

AI summary

The disclosure concerns a differential assembly (4) comprising a gear wheel (6) having a rotational axis (10), a differential cross (12) arranged within the gear wheel (6) with arms (14) of the differential cross (12) arranged perpendicularly to the rotational axis (10), differential pinions (16) rotatably arranged on the arms (14) of the differential cross (12), a first outgoing axle (18) provided with a first differential gear (20), and a second outgoing axle (22) provided with a second differential gear (24), the first and second outgoing axles (18, 22) extending in opposite directions concentrically with the rotational axis (10) and the first and second differential gears (20, 24) engaging with the differential pinions (16). An inner circumference of the gear wheel (6) is provided with radially extending recesses (26). Each arm (14) of the differential cross (12) engages with one of the radially extending recesses (26) via an interference fit.