Regenerative Braking Control for Front-Wheel Slip Stability
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Solution Overview
Problem
Existing vehicle control systems face challenges in maintaining vehicle behavior stability during regenerative braking, particularly in preventing wheel slip and ensuring adequate braking force, as they struggle to accurately predict changes in road conditions and braking dynamics.
Innovation Solution
A vehicle control system that includes a rotating electric machine control unit and a friction braking control unit, which blocks the pressure medium flow to the friction brake mechanism of a slipping wheel, increases the pressure medium pressure, and adjusts the regenerative braking torque to friction braking torque to prevent insufficient braking and instability, using a predetermined coefficient to ensure stable braking forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the friction braking force is increased to eliminate wheel slip, then the wheel slip is reduced, but the vehicle behavior stability deteriorates due to pressure fluctuations in the hydraulic pressure circuit
Solution Approach 1:
The control device increases the friction braking force in advance before the wheel slip becomes severe, and blocks the pressure medium flow to the friction brake mechanism proactively. This preliminary action prevents the need for sudden large increases in braking force that would cause hydraulic pressure fluctuations and vehicle behavior instability.
Solution Approach 2:
The control device introduces an intermediary mechanism by blocking the pressure medium flow to the friction brake mechanism while simultaneously controlling the regenerative braking force. This intermediary approach allows smooth transition between braking forces and avoids direct, sudden changes in hydraulic pressure that would destabilize vehicle behavior.
2Force
If the regenerative braking force is replaced with friction braking force, then the braking force is maintained, but the braking force becomes insufficient due to pressure fluctuations in the hydraulic pressure circuit
Solution Approach 1:
The control device increases the friction braking force in advance before the wheel slip becomes severe, and blocks the pressure medium flow to the friction brake mechanism proactively. This preliminary action prevents the need for sudden large increases in braking force that would cause hydraulic pressure fluctuations and vehicle behavior instability.
Solution Approach 2:
The control device introduces an intermediary mechanism by blocking the pressure medium flow to the friction brake mechanism while simultaneously controlling the regenerative braking force. This intermediary approach allows smooth transition between braking forces and avoids direct, sudden changes in hydraulic pressure that would destabilize vehicle behavior.
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 effectively eliminates wheel slip, prevents insufficient braking force, and stabilizes vehicle behavior by dynamically adjusting the braking forces, ensuring a stable and appropriate braking force distribution across wheels.
Implementation Method 1
a friction brake mechanism for a plurality of wheels including a predetermined wheel
Implementation Method 2
a rotating electric machine configured to transmit and receive torque to and from a predetermined wheel
Implementation Method 3
a hydraulic pressure circuit for friction braking
Data Source
AI summary
A vehicle control system includes an electric braking control unit that controls a hydraulic pressure generating unit, a behavior control unit that controls each brake mechanism, a front motor control unit and a rear motor control unit that control respective rotating electric machines, and an integrated control unit. The behavior control unit blocks the flow of a working medium of the hydraulic pressure generating unit to each front brake mechanism when a slip has occurred at the front wheels during execution of regenerative braking by the front motor control unit. The electric braking control unit increases the pressure of a pressure medium of the hydraulic pressure generating unit compared to when no slip has occurred at the front wheels.