EV Power Transmission Layout for Multi-Mode Torque Distribution
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Solution Overview
Problem
Existing power transmission systems for electric vehicles lack efficient configurations for achieving front-wheel drive, rear-wheel drive, and four-wheel drive modes, leading to increased vehicle weight and production costs, as well as suboptimal performance on rough roads and off-road conditions.
Innovation Solution
A power transmission apparatus with a motor shaft, input shafts, shifting sections, and a mode conversion unit, including a dog clutch, that allows for selective torque transmission to either the front or rear wheels, enabling multiple drive modes with minimized clutch slip loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a multi-stage shifting apparatus is provided to increase starting torque and improve electric efficiency, then the drive torque and electric efficiency are improved, but the vehicle weight and production cost increase
Solution Approach 1:
The patent merges the functions of multiple input shafts (first and second input shafts) into a single integrated transmission system that shares common components such as the output shaft, transfer gears, and differential mechanism. This consolidation achieves multi-stage shifting capability while avoiding the weight penalty of completely separate transmission systems for each input shaft.
Solution Approach 2:
The transmission system is designed with universal components that serve multiple functions: the output shaft and transfer gears can transmit torque to both front and rear wheels, the differential mechanism handles both FWD and 4WD modes, and the clutch system manages multiple input shafts. This multi-functionality reduces overall system weight compared to dedicated systems for each function.
2Power
If a multi-stage shifting apparatus is provided to increase starting torque and improve electric efficiency, then the drive torque and electric efficiency are improved, but the production cost increases
Solution Approach 1:
The patent combines multiple transmission functions into a single integrated apparatus that uses shared components (output shaft, transfer drive gears, transfer driven gears, differential mechanism). This reduces the total number of parts compared to having separate transmission systems for each input shaft, thereby lowering manufacturing complexity and production cost.
Solution Approach 2:
The transmission system employs universal components that perform multiple functions: the same output shaft and gear set handle both FWD and 4WD torque distribution, the differential mechanism serves both drive modes, and the clutch system manages multiple input shafts. This multi-functionality reduces part count and assembly complexity, leading to lower production costs.
3Adaptability or versatility
If a power transmission apparatus is configured to achieve four-wheel drive mode for rough road escape and off-road performance, then the vehicle behavior and marketability are enhanced, but the device complexity increases
Solution Approach 1:
The patent segments the power transmission system into distinct functional modules: input shaft selection (via clutches), torque shifting (via synchronizers and gear sets), front-rear wheel distribution (via transfer gears and differential), and final drive (via axle gears). This modular segmentation allows the system to achieve 4WD capability while maintaining manageable complexity through clear functional separation and standardized interfaces between modules.
Solution Approach 2:
The transmission system employs dynamic torque distribution capabilities where the clutch mechanism can selectively engage or disengage input shafts, the synchronizer enables smooth gear changes, and the differential mechanism dynamically allocates torque between front and rear wheels based on driving conditions. This dynamic adaptability provides versatile drive modes (FWD, RWD, 4WD) without requiring a completely rigid and complex mechanical structure for each mode.
Data Source
AI summary
A power transmission apparatus of an electric vehicle includes a motor shaft fixed to a drive motor and receiving the torque of the drive motor, a first input shaft disposed on a same axis with and selectively connectable to the motor shaft, a second input shaft coaxially disposed with the first input shaft, and selectively connectable to the motor shaft, front and rear wheel driving devices for driving front and wheels, a first shifting section for shifting a torque of the first input shaft and selectively transmit the shifted torque to the front wheel driving device, a second shifting section for shifting a torque of the second input shaft and selectively output the shifted torque, and a mode conversion unit of transferring an output torque of the second shifting section to at least one of the front wheel driving device and the rear wheel driving device.