Four-Wheel Drive Torque Distribution Without Front-Rear Coupling
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Solution Overview
Problem
Existing four-wheel drive electric vehicles face limitations in controlling driving force distribution to all wheels due to the need for differential revolution absorption mechanisms like couplings, which restricts torque control freedom, especially during turns.
Innovation Solution
A drive apparatus utilizing two electric motors, each with a differential mechanism, and a propeller shaft to distribute torque to all wheels without a front-rear differential revolution absorbing mechanism, allowing for independent control of left-front, right-front, left-rear, and right-rear wheels through motor output adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a differential revolution absorbing mechanism like a coupling is used to transmit torque between front and rear axles, then torque can be transmitted between axles, but the freedom of torque control is restricted especially during turns
Solution Approach 1:
The patent removes the front-rear differential revolution absorbing mechanism (coupling) from the drivetrain. Each axle is equipped with its own differential mechanism and electric motor, allowing independent torque control of front and rear axles without mechanical coupling constraints, thereby extracting the restrictive element while maintaining torque transmission capability
Solution Approach 2:
The drivetrain is segmented into independent front and rear drive units, each with its own motor and differential. This segmentation allows each axle to operate independently regarding revolution absorption, eliminating the need for a front-rear coupling mechanism while maintaining four-wheel drive functionality
2Reliability
If a coupling mechanism is used to absorb differential revolution between front and rear wheels, then torque transmission is enabled, but device complexity increases
Solution Approach 1:
The coupling mechanism is completely removed from the system. Torque transmission between front and rear axles is achieved through independent motor control rather than mechanical coupling, extracting the complex mechanical element while preserving the essential torque transmission function
Solution Approach 2:
The mechanical coupling system is replaced with an electrical control system. Each axle has its own electric motor that can independently control torque output, substituting mechanical revolution absorption with electronic torque management
Data Source
AI summary
A drive apparatus for an electric-motor four-wheel drive vehicle includes first and second motors, first and second differential mechanisms, and a propeller shaft. The vehicle includes a first wheel pair including first left and right wheels and a second wheel pair including second left and right wheels and positioned on opposite side to the first wheel pair in a front-rear direction. The first and second motors are configured to output first output torque and second output torque, respectively. The first differential mechanism is configured to distribute the first output torque to a first torque-transmitting member coupled to the first left wheel and a third torque-transmitting member coupled to the propeller shaft. The second differential mechanism is configured to distribute the second output torque to the third torque-transmitting member and a second torque-transmitting member coupled to the first right wheel.