Coaxial Electric Axle Reducer for Compact High-Torque Range Shifting
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Solution Overview
Problem
Existing electric beam axles in hybrid and electric vehicles face challenges in fitting the electric motor and gearing/gearbox within a limited space envelope while maintaining high and low range gearing capabilities for normal and high torque driving conditions.
Innovation Solution
A coaxially aligned design incorporating a planetary reducer, shiftable high ratio reducer, and differential, featuring a compound planetary gearset with stepped planet gears and clutches, allowing for efficient torque transfer and gear ratio shifting between high and low ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional separate high and low range gearboxes are used, then high and low range gearing capabilities are achieved, but the space envelope required increases significantly
Solution Approach 1:
The patent combines the planetary reducer and shiftable high ratio reducer into a single integrated coaxial assembly where the ring gear of the planetary reducer is positioned radially inwardly of the small planet gears of the shiftable high ratio reducer. This merging of two separate gearbox functions into one compact unit achieves both high and low range gearing capabilities while significantly reducing the overall space envelope required.
Solution Approach 2:
The design nests the planetary reducer within the shiftable high ratio reducer by positioning the ring gear of the planetary reducer radially inwardly of the small planet gears of the shiftable high ratio reducer. This nested configuration allows the smaller planetary reducer to be housed within the larger shiftable high ratio reducer structure, maximizing space utilization and achieving compact high and low range gearing in a single coaxial assembly.
2Force
If high ratio gearing is used for high torque applications, then torque multiplication is improved, but the complexity of the gearing system increases
Solution Approach 1:
The shiftable high ratio reducer incorporates a shiftable planet carrier that can selectively engage different gear sets through clutches, allowing the system to dynamically shift between high and low range gearing modes. This dynamic shifting mechanism provides high torque multiplication when needed while maintaining manageable system complexity through automated engagement control.
Solution Approach 2:
The integrated coaxial assembly serves multiple functions simultaneously: the planetary reducer provides primary gear reduction, while the shiftable high ratio reducer provides additional torque multiplication and range shifting. This multi-functional design achieves high torque capabilities for both normal and high torque driving conditions within a single unified gearing system.
Data Source
AI summary
An electric beam axle includes an electric motor, a shiftable reducer, a planetary reducer, and a final drive. The shiftable reducer can include a planetary gearset and the final drive can include a differential. The electric motor, shiftable reducer, planetary reducer, and the final drive are aligned coaxially providing a radially and axially compact electric beam axle.