High-Speed Electric Drive Module With Split-Torque Gear Reduction
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Solution Overview
Problem
Existing electrified vehicles face challenges in providing a high-speed electric drive module that achieves maximum power density, efficiency, reduced cost, and meets noise vibration harshness (NVH), reliability, and durability requirements while minimizing mass and cost.
Innovation Solution
A compact electric drive module design with a torque split at the electric motor, utilizing multiple gear meshing stages to achieve high reduction ratios and avoid unequal load sharing, incorporating a differential and multiple bearings to support the gear components, and integrating the differential within the electric motor housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple gear meshing stages are used to achieve high reduction ratios, then the gear reduction capability is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple gear reduction functions into a single integrated housing structure. The first and second pinion gears, transfer gears, final drive pinion gears, and final drive gears are all housed within a common housing that integrates support functions, reducing the number of separate components and assemblies needed while achieving the required high reduction ratios.
Solution Approach 2:
The housing structure serves multiple functions simultaneously: it supports the electric motor, houses all gear components, provides bearing mounting locations, and facilitates torque transfer. This multi-functionality reduces overall device complexity by eliminating the need for separate structural components for each function.
2Weight of moving object
If the differential is integrated within the electric motor housing, then the mass is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The differential is integrated within the same housing that contains the electric motor and gear train. This consolidation eliminates the need for separate housings and mounting structures, reducing total mass while the modular bearing support locations maintain manufacturing feasibility.
Solution Approach 2:
The housing is designed with distinct, modular bearing support locations and gear mounting positions that can be manufactured and assembled separately with controlled tolerances, then integrated as a complete unit. This segmentation allows each component to be manufactured to standard precision levels while achieving the required overall alignment.
3Power
If first and second pinion gears are used to drive transfer gears, then the torque distribution is improved, but the device complexity increases
Solution Approach 1:
The patent uses a symmetric dual pinion-gear arrangement where first and second pinion gears both drive transfer gears in parallel. This symmetric configuration provides balanced torque distribution while maintaining manufacturing simplicity through repetition of standardized gear components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a high reduction ratio, reduced mass, and cost-effective electric drive module that meets NVH, reliability, and durability requirements, enhancing vehicle performance.
Implementation Method 1
first and second pinion gears fixed for rotation with first and second output shafts driven by the differential; first and second transfer gears fixed for rotation to respective first and second transfer shafts and meshed for rotation with the first and second pinion gears
Implementation Method 2
first and second transfer gears providing a first gear ratio reduction from the first and second pinion gears
Implementation Method 3
final drive pinion gear meshed for rotation with the final drive ring gear and provides a second gear ratio reduction from the final drive pinion gear to the final drive ring gear
Implementation Method 4
final drive ring gear driving a differential that in turn drives first and second output shafts
Implementation Method 5
first and second pinion bearings that support the rotor shaft adjacent to the respective first and second pinion gears; first and second transfer bearings that support the transfer shaft adjacent to the respective first and second transfer gears; first and second final drive bearings that support the respective first and second output shafts
Data Source
AI summary
An electrified powertrain that generates and transfers drive torque to a driveline of an electrified vehicle is provided. The electrified powertrain includes an electric drive module having an electric motor, a transfer shaft, a final drive pinion gear and a final drive ring gear. The electric motor has a rotor shaft that includes first and second pinion gears fixed for rotation thereon. The transfer shaft includes first and second transfer gears meshed for rotation with the first and second pinion gears, the first and second transfer gears providing a first gear ratio reduction from the first and second pinion gears. The final drive pinion gear is fixed for rotation on the transfer shaft. The final drive ring gear is meshed for rotation with the final drive pinion gear and provides a second gear ratio reduction from the final drive pinion gear to the final drive ring gear.