Planetary Gear Disconnect for Electric Drive Axle Weight
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Solution Overview
Problem
There is a need for an electric drive axle with a disconnect device that is compact in size and weight, and does not require complex or expensive components, to allow for decoupling of the electric motor from the vehicle wheels without limiting vehicle speed.
Innovation Solution
The electric drive axle incorporates a planetary gear system with a clutch assembly, including a sun gear, planet gears, an annulus, and a differential mechanism, which allows for selective coupling and decoupling of the gears to achieve a desired torque transfer while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a disconnect device is added to decouple the electric motor from the vehicle wheels, then vehicle speed is not limited by the electric motor, but the device complexity and size increase
Solution Approach 1:
The disconnect device is merged with the existing differential mechanism and gear system. The clutch assembly is integrated into the differential case, and the gear train (including planetary gears) serves dual purposes of speed reduction and disconnect functionality. This consolidation eliminates the need for separate disconnect components, resolving the contradiction between adaptability and device complexity.
2Adaptability or versatility
If a disconnect device is added to decouple the electric motor from the vehicle wheels, then vehicle speed is not limited by the electric motor, but the weight of the drive axle increases
Solution Approach 1:
The disconnect functionality is combined with existing structural components (differential case, gear train, planetary gears) rather than adding separate weighted components. The clutch assembly utilizes the existing housing and mounting structures, minimizing additional weight while achieving the desired disconnect capability for extended vehicle speed range.
3Reliability
If complex and expensive components are used for the disconnect device, then reliable decoupling is achieved, but manufacturing cost increases
Solution Approach 1:
The gear train and planetary gears serve multiple functions: speed reduction, torque multiplication, and disconnect mechanism. The clutch assembly integrates with the differential case and gear components, allowing a single set of components to perform multiple functions reliably. This multi-functionality reduces the need for specialized expensive components while maintaining disconnect reliability.
4Weight of moving object
If the disconnect device is made compact, then the drive axle remains lightweight, but the mechanism becomes more complex
Solution Approach 1:
The disconnect mechanism is nested within the existing differential and gear structure. The clutch assembly is housed within the differential case, and the planetary gears are integrated into the same space. This nested arrangement achieves compactness without requiring additional external components, resolving the contradiction between weight and complexity.
Data Source
AI summary
An electric drive axle including a first gear and an idler shaft having a second gear and a third gear disposed thereon, wherein the second gear cooperates with the first gear. A clutch assembly selectively couples a planetary gear system to one of the second gear and the third gear, wherein the planetary gear system is configured to produce a predetermined gear ratio between the second gear and the third gear.