Electric Four-Wheel Drive System With Independent Wheel Motors
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Solution Overview
Problem
High-performance four-wheel drive vehicles face limitations in maximum speed, weight-to-power ratio, and packaging constraints, leading to underperformance in cornering and track-driving scenarios due to increased weight and inertia.
Innovation Solution
An electric four-wheel drive system with wheel motors integrated on the semi-axles, powered by supercapacitors and configured as radial flux permanent magnet motors, allowing independent wheel control and dynamic torque management, reducing weight and complexity by eliminating the need for additional gearboxes and differential modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional four-wheel drive system with transfer case and additional drive shafts is used, then all wheels can be driven simultaneously, but the vehicle weight increases and packaging constraints are worsened
Solution Approach 1:
The patent divides the drive system into four independent wheel motors, each motorizing a separate wheel. This segmentation eliminates the need for a centralized transfer case and drive shafts, reducing overall system weight while maintaining four-wheel drive capability. Each wheel motor is independently controlled, allowing selective torque distribution to different wheels.
Solution Approach 2:
The patent replaces the conventional mechanical four-wheel drive system (transfer case, drive shafts, differentials) with electric wheel motors. This substitution eliminates complex mechanical transmission components, significantly reducing weight and packaging requirements while enabling independent control of each wheel.
2Reliability
If additional gearboxes and differential modifications are added to achieve four-wheel drive, then torque distribution is improved, but device complexity increases
Solution Approach 1:
The patent segments the torque distribution function into four independent wheel motors, each capable of independent torque control. This eliminates the need for complex centralized differential and gearbox systems, simplifying the overall drivetrain architecture while maintaining precise torque distribution capability.
Solution Approach 2:
Each wheel motor serves multiple functions: it acts as both the propulsion motor and the differential mechanism. The independent control capability of each wheel motor provides the torque distribution function that would otherwise require separate differential and gearbox components, reducing device complexity.
3Ease of operation
If large power supply systems are installed to support four wheel motors, then independent wheel actuation is enabled, but weight increases
Solution Approach 1:
The patent uses supercapacitors that can deliver high power for short durations, which is sufficient for most driving conditions. This partial action approach enables independent wheel control when needed without requiring continuously large power supply systems, reducing weight compared to systems designed for continuous high power output.
Solution Approach 2:
The patent employs supercapacitor technology which changes the power delivery parameters - providing high power for short bursts rather than continuous moderate power. This parameter change enables adequate power supply for independent wheel actuation with significantly reduced weight compared to traditional battery or generator systems.
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 system provides improved driving control and performance by enabling independent wheel actuation, reducing weight and complexity, and allowing for dynamic torque management, enhancing traction and stability during demanding driving conditions without the need for large power supplies, suitable for both dynamic driving and assistance features like automated parking.
Implementation Method 1
At least one supercapacitor (7) is provided, in particular one or several supercapacitors (7) per wheel motor (1). The at least one supercapacitor (7) can in each case be used to deliver power to the respective wheel motor (1) during acceleration and/or during regenerative braking.
Implementation Method 2
The wheel motors (1) are configured as radial flux permanent magnet motors
Data Source
AI summary
An electric four-wheel drive (E-4WD) system and control method for a motor vehicle includes four wheel motors. Each wheel motor is an electric motor configured to drive one respective wheel corresponding to the wheel motor. Each wheel motor includes a stator implemented on a suspension structure of the respective wheel and a rotor implemented on a semi-axle connected to the respective wheel to rotate together with the respective wheel relative to the stator. The wheel motors are configured to drive the wheels independently of each other.