Curved De Dion Rear Axle for EV Battery Packaging and Vibration Isolation
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Solution Overview
Problem
Commercial electric vehicles face packaging challenges due to live axle rear suspension configurations that prevent the integration of batteries within the frame rails, leading to decreased cargo and passenger space, and expose electric motors to high vibration, increasing failure likelihood and decreasing reliability.
Innovation Solution
Implementing a chassis with a curved de Dion axle that positions the electric drive unit and drivetrain between the frame rails, eliminating the need for a driveshaft, allowing batteries to be disposed within the frame rails and improving packaging, while using a dead axle suspension configuration that couples the electric motors to the frame for load-carrying capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a live axle suspension configuration is used, then high loads can be carried and drive shafts can be integrated within the axle, but the packaging features required are problematic for electric commercial vehicles and prevent battery integration within frame rails
Solution Approach 1:
The patent segments the drive system by separating the electric motor from the axle assembly. The motor is mounted independently on the vehicle frame while the axle remains a separate load-carrying component, eliminating the need for integrated drive shafts and creating space for battery integration within frame rails.
Solution Approach 2:
The patent extracts the electric motor from the traditional live axle configuration and positions it separately on the vehicle frame. This extraction removes the conflicting packaging requirements and allows both the axle to maintain its load-carrying function and the frame rails to accommodate batteries.
2Power
If a driveshaft is disposed between frame rails, then power transmission is achieved, but the space is prevented from being utilized to package other components such as batteries
Solution Approach 1:
The patent removes the driveshaft from the traditional configuration between frame rails and replaces it with a direct-drive architecture where the electric motor connects to the wheels through alternative pathways, freeing up the space between frame rails for battery installation.
Solution Approach 2:
The patent repositions the electric motor in a different spatial arrangement, mounting it on the vehicle frame rather than using a longitudinal driveshaft configuration, thereby utilizing vertical and lateral space more efficiently and enabling battery integration in the previously occupied space.
3Device complexity
If the electric motor is positioned close to the rear axle, then drive integration is achieved, but the motor is exposed to high vibration, increasing failure likelihood
Solution Approach 1:
The patent extracts the electric motor from the high-vibration environment near the rear axle and relocates it to a more stable position on the vehicle frame, reducing exposure to vibrations while maintaining effective drive integration through alternative power transmission pathways.
Solution Approach 2:
The patent introduces intermediate components such as CV axles and differentials that serve as mediators between the motor and wheels, allowing the motor to be positioned in a lower-vibration area while still achieving effective power transmission to the driven wheels.
Data Source
AI summary
A rear axle of a commercial electric vehicle includes a curved de Dion axle that includes stub axles, CV cups, each configured to receive a portion of a CV axle, and a central portion disposed downward and rearward of the stub axles. The rear axle includes a curved form factor to allow for a portion of an electric drive unit to be disposed in a manner where a hub centerline connecting the stub axles intersects the electric drive unit.