Dual-Motor EV Drivetrain With Power Disconnect for 2WD/4WD Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing driving apparatuses for electric vehicles face challenges in achieving high efficiency, high performance, and low cost within limited installation space, particularly when switching between two-wheel drive and four-wheel drive configurations, leading to issues like no-load drag, increased investment cost, and decreased travel distance and fuel efficiency.
Innovation Solution
A driving apparatus utilizing two motors and three reduction mechanisms, including a power disconnector, to optimize performance in different driving regions by selectively connecting or disconnecting power between the motors, and incorporating a parking gear and air conditioning compressor to enhance efficiency and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a motor system with rare-earth element permanent magnet is used to achieve high efficiency, then driving efficiency is improved, but cost increases
Solution Approach 1:
The motor system is segmented into two independent motors: a first motor with rare-earth element permanent magnet for high efficiency in 2WD mode, and a second motor without rare-earth elements for cost-effective 4WD auxiliary driving. This segmentation allows each motor to be optimized for its specific function and cost constraints.
Solution Approach 2:
The system dynamically switches between different motor configurations using a disconnect device. In 2WD mode, only the first motor operates; in 4WD mode, both motors operate. This dynamic operation allows the system to achieve high efficiency when needed while reducing cost by not requiring both motors to be high-efficiency units.
2Use of energy by moving object
If a disconnect device is added to eliminate no-load drag in 4WD vehicles, then fuel efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The disconnect device is merged with the differential gear assembly of the auxiliary drive source, forming an integrated unit. This combination eliminates the need for a separate disconnect mechanism while still achieving the function of disconnecting the auxiliary motor from the wheel during 2WD operation, thereby reducing no-load drag.
Solution Approach 2:
The disconnect device is designed to be automatically controlled based on driving conditions (2WD vs. 4WD mode). The system self-regulates the connection state of the auxiliary motor without requiring manual intervention or complex external control systems, simplifying the overall device architecture.
3Force
If the auxiliary drive source is set to the same torque and output specifications as the main drive source, then performance is improved, but size and volume increase
Solution Approach 1:
The auxiliary motor is designed with localized optimization: it has the same torque capability as the main motor when needed (in 4WD mode), but uses non-rare-earth permanent magnets to reduce size and cost. The motor dimensions and magnetic material are specifically tailored for auxiliary driving requirements rather than full main-drive specifications.
Solution Approach 2:
The auxiliary motor uses different magnetic material parameters (non-rare-earth permanent magnets) compared to the main motor (rare-earth permanent magnets). This parameter change allows the auxiliary motor to achieve sufficient torque for 4WD operation while reducing size, weight, and cost.
4Force
If hill climbing and towing capability are improved by changing reduction mechanism design, then performance is improved, but efficiency gain relative to investment cost decreases
Solution Approach 1:
The reduction mechanisms are designed as universal components that serve multiple functions: they provide torque multiplication for hill climbing, enable 4WD operation through the disconnect device integration, and maintain efficiency across different driving conditions. This multi-functionality reduces the need for separate specialized components.
Solution Approach 2:
The reduction mechanism is dynamically adapted through the disconnect device that can engage or disengage the auxiliary motor based on driving conditions. This dynamic configuration allows the same reduction mechanism to optimize performance for different tasks (2WD highway driving, 4WD off-road, hill climbing) without requiring multiple specialized mechanisms.
Data Source
AI summary
A driving apparatus for an electric vehicle operates by combining two motors, three reduction mechanisms, and a power disconnector so that each driving region of the electric vehicle can appropriately perform its role, thereby maintaining efficiency gain and effectiveness in relation to cost, even if required performance specifications increase, or maintaining its driving efficiency at a high level.