Roll Stability Control via Asymmetric Torque Distribution
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Solution Overview
Problem
Existing roll stability control systems for vehicles, particularly in 4×4 systems, face challenges in effectively managing driving torques and braking torques to prevent on-road rollovers, as they often induce over-steer and yaw stability issues, and do not adequately utilize the potential of all-wheel drive systems to reduce lateral forces on tires.
Innovation Solution
A method that integrates control units for brake, engine, and 4×4 systems to manage driving torques and braking torques dynamically, prioritizing and arbitrating torque distribution between wheels to prevent rollovers, using active differentials and differentials in the transfer case to adjust torque and braking forces in response to rollover conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If driving torque is increased on outside wheels to reduce lateral forces and improve roll stability, then roll stability is improved, but over-steer and yaw stability issues are induced
Solution Approach 1:
The patent applies different torque control strategies to different wheels based on their location. Specifically, it reduces driving torque on outside wheels while maintaining or increasing torque on inside wheels, creating an asymmetric torque distribution that counteracts the roll moment without inducing over-steer. This local differentiation of torque quality resolves the contradiction between improving roll stability and avoiding yaw instability.
Solution Approach 2:
Instead of the conventional approach of applying braking force to outside wheels or increasing torque on outside wheels, the patent inverts the strategy by reducing torque on outside wheels and applying torque to inside wheels. This inverted approach achieves roll stability control while avoiding the harmful over-steer effect that would result from conventional methods.
2Stability of the object's composition
If brake-based roll stability control is used to reduce lateral forces on outside wheels, then roll stability is improved, but fuel economy deteriorates due to energy loss from braking
Solution Approach 1:
The patent converts the potential harm of reduced torque (which could cause wheel slip) into a benefit by using the inside wheels as torque application points. The torque applied to inside wheels generates a roll moment that stabilizes the vehicle without the energy loss associated with braking outside wheels. This transforms what could be a stability problem into an energy-efficient stability solution.
Solution Approach 2:
The powertrain system serves the dual purpose of providing propulsion and roll stability control. By modulating torque distribution among wheels, the driving system itself provides the stability control function without requiring separate braking intervention, thereby eliminating the energy loss from brake-based control while maintaining roll stability.
3Force
If 4×4 system is engaged to provide torque to all wheels for improved traction, then traction capability is improved, but device complexity and fuel consumption increase
Solution Approach 1:
The patent implements dynamic torque distribution control within the 4×4 system, continuously adjusting torque allocation to front and rear axles based on real-time wheel slip detection and roll stability requirements. This dynamic control optimizes traction utilization while managing system complexity through adaptive rather than static torque management, allowing the system to provide full 4×4 capability only when necessary.
Solution Approach 2:
The system changes torque parameters dynamically based on operating conditions. By monitoring wheel slip ratios and roll moments, the control system adjusts torque magnitude and distribution to maintain optimal traction while minimizing energy consumption and managing driveline complexity through parameter adaptation rather than fixed complex mechanical configurations.
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
This integrated approach enhances roll stability control by reducing lateral forces on tires, minimizing the risk of rollovers, and improving the synergy between 4×4 and brake control systems, thereby enhancing overall vehicle stability and reducing the cost of implementing dynamic control systems.
Implementation Method 1
using active differentials and differentials in the transfer case to adjust torque and braking forces
Implementation Method 2
due to the friction circles at the tires, the tire lateral forces in the front and the rear wheels
Data Source
AI summary
A control system (18) and method for controlling an automotive vehicle (10) includes a number of sensors that are used to generate a potential rollover signal. In response to the potential rollover, active differentials (112, 114, 116) may be used alone or in addition to braking to prevent the vehicle from rolling over.