Hybrid Vehicle Brake Slip Stabilization via Clutch Decoupling
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Solution Overview
Problem
Conventional vehicle stabilization methods in hybrid vehicles are inadequate for managing brake slip and increased risk of slip, particularly on slippery surfaces, as they rely on slow engine torque adjustments and may exceed tire capacity, leading to instability.
Innovation Solution
A method and system that utilize a clutch to quickly decouple the internal combustion engine's torque from the drive wheels by releasing the clutch and increasing the electric motor's torque, reducing the braking torque and potentially applying a positive driving torque to stabilize the vehicle, leveraging control units for rapid torque adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine drag torque regulation is used to stabilize the vehicle, then vehicle stability is improved, but the reaction speed is too slow to prevent brake slip on slippery surfaces
Solution Approach 1:
The drivetrain is segmented into two independent torque sources: the internal combustion engine and the electric motor. The clutch separates these sources, allowing the electric motor to independently compensate for brake slip without being constrained by the slow response of the combustion engine torque regulation.
Solution Approach 2:
The electric motor acts as an intermediary between the clutch and the drive wheels, providing rapid torque adjustment to counteract brake slip. The control unit mediates between the detected slip condition and the torque application, enabling fast response compared to direct combustion engine regulation.
2Speed
If the clutch is released to decouple the internal combustion engine torque, then the reaction speed to brake slip is improved, but the device complexity increases
Solution Approach 1:
The clutch serves multiple functions: it decouples the combustion engine during rapid stabilization events, enables electric motor-only operation for quick torque changes, and maintains the hybrid powertrain architecture for normal operation. This multi-functionality justifies the added complexity.
Solution Approach 2:
The control unit automatically manages the clutch engagement/disengagement based on detected brake slip conditions, eliminating the need for manual intervention. The system self-regulates the torque distribution between the two power sources, reducing operational complexity despite the added hardware.
3Force
If both the internal combustion engine braking torque and service brake torque are applied simultaneously, then the braking force is increased, but the tire capacity is exceeded causing brake slip
Solution Approach 1:
Instead of applying full combustion engine braking torque when service brakes are already engaged, the system applies only the necessary partial torque from the electric motor to achieve the required braking effect without exceeding tire adhesion limits. This prevents brake slip while maintaining adequate braking force.
Solution Approach 2:
The system dynamically changes the torque parameter distribution between the two power sources based on operating conditions. When service brakes are applied, the combustion engine torque is reduced or eliminated, and the electric motor torque is adjusted to provide the complementary braking force needed, keeping the total torque within tire capacity limits.
Data Source
AI summary
A method and system are provided for vehicle stabilization of a hybrid vehicle in an event of brake slip of the drive wheels or an increased risk thereof. The method presupposes that the hybrid vehicle includes, between the internal combustion engine and the electric motor, a clutch by which the torque of the internal combustion engine can be decoupled from the drive wheels. With the clutch engaged, the resulting torque on the electric motor is produced by the torque of the internal combustion engine and the torque of the electric motor. The presence of a specific vehicle condition indicative of brake slip of the drive wheels or a risk thereof is recognized. If such a vehicle condition is recognized, the clutch between the internal combustion engine and the electric motor is released and the torque of the electric motor is increased.