EV Drive System Integrated Housing and Nested Planetary Gears
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Solution Overview
Problem
Electric vehicle drive systems face challenges in reducing packaging space and weight, particularly due to complex gear reduction systems and sealing issues in multi-unit housings, which lead to oil leakage and increased weight from fasteners.
Innovation Solution
A drive system design featuring a two-stage planetary gear system with a single, integrated outer housing and a hollow input gear shaft formed integrally with the sun gear, reducing axial and radial space while minimizing fasteners and enhancing sealing, and incorporating shrink-fitting for assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a complex gear reduction system is used to achieve desired output speed, then the efficiency is improved, but the packaging space requirement increases
Solution Approach 1:
The patent places the first planetary gear set underneath the wound stator, nesting the gear system within the motor assembly footprint. This allows the gear reduction system to share space with the motor components, reducing the overall packaging space while maintaining the required gear reduction efficiency
Solution Approach 2:
The patent transitions from a traditional horizontal arrangement to a vertical arrangement by positioning the first planetary gear set underneath the wound stator. This dimensional change allows efficient use of vertical space and reduces the radial packaging footprint
2Ease of manufacture
If housing is formed from two or more housing units fastened together, then the manufacturing ease is improved, but the sealing reliability deteriorates due to joints and fasteners
Solution Approach 1:
The patent merges the motor housing and gearbox housing into a single integrated housing structure. This eliminates the joints and fasteners between separate housing units, removing the leakage paths and sealing issues while maintaining manufacturing feasibility through integral forming processes
3Adaptability or versatility
If power electronic components are mounted on the housing, then the operational capability is improved, but the oil leakage risk increases due to pressure on housing joints
Solution Approach 1:
The integrated housing design eliminates separate joints that would be subjected to pressure from mounted power electronic components. By having a single continuous housing structure, there are no inter-joint sealing surfaces to fail under the weight and mounting pressure of power electronic components
4Productivity
If stepped planetary gear set with splined connection is used, then the gear efficiency is improved, but the radial packaging space increases due to sun gear size
Solution Approach 1:
The patent positions the first planetary gear set underneath the wound stator, nesting it within the available space. This arrangement allows the use of efficient stepped planetary gear sets while minimizing their radial footprint by utilizing the vertical space under the stator
Data Source
AI summary
A drive system for powering the wheels of an electric vehicle is disclosed. The drive system includes an electric motor having a stator and a rotor, and one or more planetary gear sets operably connected to the electric motor and the wheels. The drive system includes one or more configurations that reduce packaging space, reduce the weight of the drive system, and/or provide cooling functions.