Electric Axle Assembly Layout for Compact Torque Transmission

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Solution Overview

Problem

Existing axle assemblies with electric motor modules and gear reduction modules face challenges in optimizing torque transmission efficiency and packaging space, particularly in vehicles requiring compact designs.

Innovation Solution

The axle assembly integrates an electric motor module and gear reduction module within a differential carrier, positioning the electric motor module inside the carrier to reduce axial length and center of mass, while the gear reduction module is externally mounted, allowing for modular construction and standardized components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the electric motor module is positioned inside the differential carrier, then the axial length and center of mass are reduced, but the torque transmission efficiency and packaging space optimization become challenging

Engineering Contradiction:
Improveaxial lengthVSAvoidtorque transmission efficiency
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The electric motor module is nested inside the differential carrier, with the motor positioned within the carrier's internal space. This nesting arrangement reduces the overall axial length of the axle assembly while maintaining torque transmission capability through the carrier structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The axle assembly is segmented into modular components: the electric motor module, gear reduction module, and differential carrier. This segmentation allows independent optimization of each module, enabling the motor to be positioned inside the carrier for compactness while the gear reduction module handles torque transmission externally.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If the gear reduction module is externally mounted, then modular construction and standardized components are enabled, but the packaging space and torque transmission efficiency are compromised

Engineering Contradiction:
Improvemodular constructionVSAvoidpackage space
Core Design Contradiction:
Ease of manufactureVSVolume of stationary object

Solution Approach 1:

The gear reduction module is separated as an external component from the differential carrier, enabling modular construction. This allows the gear reduction module to be manufactured and standardized independently, then mounted externally to the carrier, facilitating ease of manufacture and assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The externally mounted gear reduction module serves as a universal component that can be adapted to different axle assembly configurations. Its external mounting position allows it to function as a standardized element that can be integrated with various motor and carrier combinations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Volume of moving object

If the electric motor module is integrated within the differential carrier, then compact design is achieved, but the torque transmission path and packaging space optimization become complex

Engineering Contradiction:
Improvepackage spaceVSAvoidtorque transmission path
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The electric motor module is nested within the differential carrier, maximizing space utilization. This nested configuration reduces the overall package volume by eliminating wasted space between components and creating a compact integrated assembly.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The torque transmission path is segmented into distinct functional modules: the motor module inside the carrier, and the gear reduction module externally mounted. This segmentation simplifies the torque transmission path by creating clear, manageable stages of power transmission rather than a complex integrated path.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3750732B1Axle assembly having an electric motor module and a gear reduction module
Publication Date: 2026.03.25 ARVINMERITOR TECHNOLOGY LLC
  • EP3750732B1 patent drawingFigure 1
  • EP3750732B1 patent drawingFigure 2
  • EP3750732B1 patent drawingFigure 3

AI summary

An axle assembly having an axle housing, a differential carrier, an electric motor module, and a gear reduction module. The differential carrier may be mounted to the axle housing and may rotatably support a differential. The electric motor module may be disposed in the differential carrier. The gear reduction module may be disposed adjacent to a differential carrier cover and may transmit torque from the electric motor module to the differential via a drive pinion.