Inhibiting Automatic Engine Stop via Dynamic Speed Thresholds
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Solution Overview
Problem
Automatic engine stopping and starting in vehicles can lead to repeated cycles, reducing fuel conservation and irritating occupants due to frequent brake pedal application and release during deceleration, which disrupts the driving experience and fuel efficiency.
Innovation Solution
Inhibiting automatic engine stopping when the vehicle speed is between specific thresholds and allowing engine stopping and starting based on dynamic conditions such as brake pedal release, battery state, and vacuum levels, thereby reducing frequent engine cycles and maintaining fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If automatic engine stopping is implemented to conserve fuel, then fuel economy is improved, but repeated engine stopping and starting occurs when drivers apply and release brake pedal during deceleration, reducing fuel conservation benefits and irritating occupants
Solution Approach 1:
The patent implements dynamic threshold adjustment where the automatic engine stop threshold speed is modified based on recent brake pedal activity. When the brake pedal has been recently applied and released, the threshold is adjusted to prevent repeated engine cycling. This dynamic adaptation allows the system to learn driver behavior patterns and adjust accordingly, maintaining fuel economy while preventing irritating repeated engine stops and starts during normal deceleration maneuvers
Solution Approach 2:
The system incorporates feedback from brake pedal position sensors and engine stop/start event history to continuously adjust the automatic engine stop threshold. By monitoring whether the brake pedal has been recently applied and released, the system receives feedback about driver intent and adjusts the engine stop threshold to prevent premature or repeated engine cycling, thereby maintaining both fuel economy and driver comfort
2Loss of energy
If the engine stop threshold is lowered to increase fuel conservation, then more fuel is saved, but the engine stops at higher speeds including during normal deceleration, causing repeated stopping and starting that disturbs occupants
Solution Approach 1:
The patent makes the engine stop threshold dynamic rather than fixed, adjusting it based on vehicle operating conditions including recent brake pedal activity. When deceleration with recent brake application is detected, the threshold is raised to prevent engine stop during normal driving maneuvers. This dynamic adjustment allows the system to achieve fuel conservation benefits while avoiding occupant disturbance from repeated engine cycling during normal deceleration
Solution Approach 2:
The system changes the threshold parameter adaptively based on detected driving patterns. By monitoring brake pedal activity and adjusting the engine stop threshold parameter accordingly, the system prevents engine stopping during normal deceleration maneuvers while still enabling fuel-saving engine stops during prolonged idling conditions, thus reducing both fuel consumption and occupant disturbance
Data Source
AI summary
Systems and methods for operating a vehicle that includes an engine that may be automatically stopped and started are described. In one example, the inhibiting or preventing automatic engine stopping may be performed when a human driver releases a brake pedal, which causes the engine to automatically start, and the inhibiting may continue until vehicle speed exceeds a speed where the engine was automatically stopped.