Axle Assembly Layout With Drop Gear Set for Thermal Balance

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Solution Overview

Problem

Current axle assemblies with electric motor-driven transmissions face challenges in efficiently managing torque transmission and gear ratios, leading to inefficiencies and potential thermal and mechanical issues due to the integration of electric motors and countershaft transmissions on the same side of the housing, which affects weight distribution, thermal management, and component longevity.

Innovation Solution

The axle assembly design incorporates a countershaft transmission with a drop gear set and differential assembly, allowing for multiple gear ratios with a single set of countershaft gears, thermally separates the electric motor from other components, and improves weight distribution by locating the electric motor and countershaft transmission on opposite sides of the differential assembly, reducing the number of gears and associated costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the electric motor and countershaft transmission are integrated on the same side of the housing, then the device complexity is reduced, but the thermal management deteriorates and weight distribution becomes unbalanced

Engineering Contradiction:
Improveintegration of componentsVSAvoidthermal management
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent divides the housing into left and right sides, placing the electric motor on one side and the countershaft transmission on the other side. This spatial segmentation separates heat-generating components from each other, improving thermal management while maintaining integration within the single housing structure.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the electric motor and countershaft transmission are integrated on the same side of the housing, then the device complexity is reduced, but the weight distribution becomes unbalanced

Engineering Contradiction:
Improveintegration of componentsVSAvoidweight distribution
Core Design Contradiction:
Device complexityVSWeight of moving object

Solution Approach 1:

The patent segments the housing into left and right sides, placing the electric motor on one side and the countershaft transmission on the other side. This spatial segmentation distributes weight more evenly across the housing, improving weight balance while maintaining integration within the single housing structure.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If multiple gear ratios are achieved with a single set of countershaft gears, then the device complexity is reduced and manufacturing cost decreases, but the torque transmission efficiency may be compromised

Engineering Contradiction:
Improvenumber of gear setsVSAvoidtorque transmission efficiency
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent employs a dynamic gear selection mechanism where a selector member can engage different countershaft gears (first, second, or third) to provide multiple gear ratios. This dynamic switching capability allows the system to optimize torque transmission efficiency for different operating conditions while maintaining a single set of countershaft gears, reducing complexity compared to multiple fixed gear sets.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3805603B1Axle assembly having a multi-speed transmission and a drop gear set
Publication Date: 2024.03.06 ARVINMERITOR TECHNOLOGY LLC
  • EP3805603B1 patent drawingFigure 1
  • EP3805603B1 patent drawingFigure 2
  • EP3805603B1 patent drawingFigure 3A

AI summary

An axle assembly having a drop gear set and a countershaft transmission. The drop gear set may operatively connect a rotor of an electric motor to a countershaft. The countershaft transmission may operatively connect the countershaft to a drive pinion. The electric motor and the countershaft transmission may be positioned on opposite sides of a differential assembly.