Coaxial Electric Axle Reducer for Two-Speed Packaging Constraints
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Solution Overview
Problem
Existing electric beam axles for 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.
Innovation Solution
A coaxially aligned design incorporating an electric motor, planetary ratio reducer, shiftable high ratio reducer, and differential, featuring a compound planetary gearset with stepped planet gears and clutches for selective engagement, allowing for high and low range gearing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional separate high and low range gearing systems are used, then high and low range gearing capabilities are achieved, but the space envelope required increases beyond available space
Solution Approach 1:
The patent combines the high range reducer and low range reducer into a single integrated coaxial assembly where both planetary gearsets share a common axis and housing. The high range planetary gearset and low range planetary gearset are arranged concentrically, allowing the system to achieve both high and low range gearing capabilities within a compact volume that would otherwise require separate gearboxes.
Solution Approach 2:
The patent employs a nested configuration where the low range planetary gearset is positioned inside the high range planetary gearset, both sharing the same central axis. The sun gear, planet gears, and ring gear of the low range reducer are arranged within the outer dimensions of the high range reducer components, effectively nesting one gearset within the other to minimize overall volume.
2Volume of moving object
If coaxial alignment is used, then space envelope is reduced, but device complexity increases
Solution Approach 1:
The patent divides the coaxial gearing system into distinct functional segments: the high range planetary gearset and the low range planetary gearset. Each gearset is independently designed with its own sun gear, planet gears, ring gear, and clutch mechanism, allowing for modular assembly and maintenance while maintaining the compact coaxial configuration.
Solution Approach 2:
The patent incorporates selectable clutch mechanisms that dynamically engage or disengage specific planetary gearsets based on driving conditions. The selectable high range clutch and selectable low range clutch allow the system to switch between high range and low range modes, providing dynamic adaptability that simplifies control while maintaining the complex coaxial structure.
Data Source
AI summary
An electric beam axle includes an electric motor, a high-speed reducer, a shiftable reducer, and a differential. The shiftable reducer includes a planetary gearset and the differential at least one of a spur or bevel gear differential. The electric motor, high-speed reducer, shiftable reducer and rolling differential are aligned coaxially providing a radially compact electric beam axle.