Neutral Engine Start Stabilization via Parking Brake
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Solution Overview
Problem
Electrified vehicles face challenges in starting the engine when the battery state of charge is depleted, leading to potential unintended vehicle movement if started in neutral gear without proper stabilization.
Innovation Solution
Engaging a parking brake when the battery state of charge falls below a predefined threshold, followed by starting the engine, and subsequently disengaging the brake after engine startup, while monitoring torque at the wheels to ensure safe neutral engine starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the engine is started in neutral gear when battery state of charge is depleted, then the vehicle operation can be extended, but unintended vehicle movement may occur
Solution Approach 1:
The system performs preliminary detection of battery state of charge before attempting engine start. When SOC falls below the threshold, the system proactively engages the parking brake to stabilize the vehicle before the engine start sequence initiates, preventing unintended movement during the starting process
Solution Approach 2:
The parking brake acts as an intermediary mechanism between the depleted battery state and the engine start process. By introducing this intermediate stabilization step, the system allows engine starting to proceed even when battery power is low, while the parking brake compensates for the lack of electrical power by mechanically securing the vehicle
2Reliability
If the parking brake is engaged to prevent vehicle movement, then vehicle stability is improved, but the complexity of the control system increases
Solution Approach 1:
The control system integrates multiple functions into existing components. The brake control module that normally manages brake engagement for stopping also handles parking brake engagement for engine start stabilization. The system reuses existing sensors (wheel speed, brake status) and actuators (parking brake mechanism), avoiding the need for dedicated new components
Solution Approach 2:
The system uses already-available vehicle state information (battery SOC from the power management system, gear position from the transmission control) to automatically trigger the parking brake engagement. No additional sensors or complex decision-making algorithms are required - the system self-activates based on predefined conditions using existing data streams
Data Source
AI summary
A method according to an exemplary aspect of the present disclosure includes, among other things, controlling an electrified vehicle by engaging a parking brake if a battery state of charge is depleted below a predefined threshold.