E-Axle Multi-Speed Gearbox for Torque and Durability Balance
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Solution Overview
Problem
Conventional electric powertrains are inefficient due to high-speed operation, which leads to reduced durability, increased noise, and vibration, and are not adaptable to a wide range of vehicles, resulting in high production costs and complexity.
Innovation Solution
A compact and robust electric powertrain design with a power take-off system that includes multiple gear ratios and independent control of speed and torque, allowing for optimized manufacturing and efficiency across various vehicle types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a fixed speed ratio gearbox is used to achieve high torque reduction, then torque demand at wheels is met, but motor efficiency decreases in cruise mode and transmission durability reduces due to high-speed stresses
Solution Approach 1:
The patent applies a multi-speed gearbox with variable speed ratios instead of a fixed ratio gearbox. This allows the transmission system to dynamically adjust the speed ratio according to operating conditions, enabling the motor to operate in optimal efficiency ranges across different driving scenarios while reducing high-speed stresses on transmission components.
Solution Approach 2:
The patent changes the speed ratio parameter of the transmission system by providing multiple gear ratios (at least two different ratios). This allows optimization of the torque-speed characteristics for different operating conditions, improving both motor efficiency and transmission durability by avoiding continuous high-speed operation.
2Force
If high speed reduction ratio is achieved with multiple reduction stages, then torque demand is met, but space requirements increase
Solution Approach 1:
The patent combines multiple reduction stages into a compact multi-speed gearbox assembly. By merging the planetary gear mechanism with the speed ratio switching system, the patent achieves high torque reduction ratios in a more space-efficient configuration compared to conventional multi-stage transmissions.
Solution Approach 2:
The patent employs a planetary gear mechanism where gears are nested within each other, allowing multiple reduction stages to be compacted into a smaller volume. The planetary arrangement enables high reduction ratios while minimizing the axial and radial space required for the transmission system.
3Power
If gears rotate at high speed to meet power demand, then power output is sufficient, but lubrication effectiveness decreases and noise increases
Solution Approach 1:
The patent dynamically adjusts the operating speed of gears by providing multiple speed ratios. This allows the system to operate at lower speeds when possible, improving lubrication effectiveness and reducing noise and vibration, while still meeting power demand through appropriate gear selection.
Solution Approach 2:
The patent changes the rotational speed parameter of the gears by switching between different gear ratios. This enables optimization of the noise-vibration-lubrication characteristics by operating at lower speeds when the application allows, while maintaining sufficient power output through mechanical advantage.
4Power
If conventional electric powertrain architecture is used, then basic propulsion is achieved, but adaptability to different vehicle types decreases and production costs increase
Solution Approach 1:
The patent designs a powertrain architecture with a multi-speed gearbox and power take-off system that can be adapted to various vehicle types and applications. The modular design with configurable speed ratios and external power transmission capabilities makes the system versatile for different duty cycles and vehicle configurations, reducing the need for application-specific customizations.
Data Source
AI summary
an electric powertrain integrated into a vehicle axle. Such electric axle (or “E-axle”) is a front or rear axle that includes an axle body (or “housing”) adapted to receive a powertrain, which is arranged to provide torque to the wheels of the axle. The “E-Axle” is a compact and economical electric drive solution for battery electric vehicles, fuel cells and hybrid applications. The electric motor(s), electronics and transmission are combined in a compact unit that directly drives the wheels provided at the longitudinal ends of the axle.