EV Reducer Coaxial Planetary Layout for Compact Assembly
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Solution Overview
Problem
Existing reducers for electric vehicles face challenges in achieving a simple, compact configuration with improved mountability, reduced weight and costs, while ensuring assembly properties and maintainability, and durability.
Innovation Solution
A reducer design featuring a coaxial differential with a planetary gear train that includes a sun gear, carrier, and ring gear, supported by bearings and an oil supply system, allowing for axial sliding engagement and reduced component count, enabling efficient power transmission and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional reducer structure is used, then the reduction ratio can be achieved, but the overall length and complexity increase
Solution Approach 1:
The drive shaft is merged with the input shaft by making the drive shaft penetrate through the input shaft, eliminating the need for separate mounting structures and reducing overall length while maintaining functional separation through magnetic coupling
Solution Approach 2:
The drive shaft is nested within the input shaft, with the drive shaft penetrating through the input shaft along its longitudinal axis. This nested configuration allows both shafts to occupy the same spatial envelope, significantly reducing the overall length of the reducer assembly
2Reliability
If more components are added to ensure durability and assembly properties, then reliability improves, but weight and costs increase
Solution Approach 1:
The magnetic coupling mechanism replaces traditional mechanical connections such as keys, splines, or set screws between the drive shaft and planetary gear train. This substitution eliminates additional fastening components, reduces weight, and maintains reliable power transmission through magnetic attraction while allowing for easier assembly and disassembly
Solution Approach 2:
The input shaft serves multiple functions: it acts as both the input transmission shaft and the structural housing for the drive shaft penetration. This multi-functionality eliminates the need for separate bearing housings and mounting brackets, reducing overall component count and weight while maintaining structural integrity
3Adaptability or versatility
If a compact configuration is implemented, then vehicle mountability improves, but manufacturing precision requirements increase
Solution Approach 1:
The magnetic coupling creates a uniform magnetic field distribution between the drive shaft and planetary gear train, establishing an equipotential energy state that naturally centers the components. This magnetic centering effect compensates for minor manufacturing tolerances and ensures consistent assembly without requiring ultra-precise machining
Solution Approach 2:
The magnetic coupling allows for dynamic adjustment during assembly, where the magnetic attraction force naturally guides the drive shaft into its correct position relative to the planetary gear train. This self-aligning characteristic reduces the need for precise pre-positioning and facilitates easier assembly while maintaining compact dimensions
Data Source
AI summary
A reducer for an electric vehicle includes an input shaft connected to a motor, a differential disposed coaxially with the input shaft and relatively rotatable, a planetary gear train configured to decelerate power of the input shaft and transmit the power to a differential casing of the differential, and a drive shaft configured to penetrate the input shaft and coupled to one side gear of the differential.