Intermittent Engine Restart for Automatic Stop-Start Systems
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Solution Overview
Problem
Current vehicle stop/start systems cause delays when the engine restart is initiated before it has come to a complete stop, leading to operator frustration and reduced vehicle performance due to the requirement for the engine speed to drop to 0 rpm before restarting.
Innovation Solution
The system determines if stop/start enablement conditions are met and allows for an intermittent engine restart if the engine speed is above a threshold, reducing the delay by initiating the restart before the engine reaches 0 rpm, and delaying the restart until it does if the speed is below the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine must come to a complete stop (0 rpm) before restart is initiated, then the engine restart sequence can be reliably executed using the vehicle starter, but there is a delay between operator restart request and engine restart sequence beginning
Solution Approach 1:
The system initiates the engine restart sequence before the engine speed reaches 0 rpm. The controller monitors engine speed and triggers the restart sequence at a predetermined threshold speed (e.g., 50-100 rpm) before complete stop, eliminating the waiting delay while ensuring reliable restart through starter motor engagement and fuel/ignition system activation.
Solution Approach 2:
The patent introduces dynamic decision-making based on real-time engine speed conditions. The controller continuously monitors engine speed and selectively applies different restart strategies: intermittent restart when speed > threshold, and delayed restart when speed < threshold. This dynamic adaptation resolves the contradiction by optimizing restart timing based on actual engine state.
2Ease of operation
If the engine restart is initiated before it has come to a complete stop, then operator frustration is reduced and vehicle performance is improved, but the engine may not be in the optimal state for restart
Solution Approach 1:
The system changes the operational parameter threshold for initiating restart from 0 rpm to a predetermined speed threshold (e.g., 50-100 rpm). This parameter change allows restart initiation during the engine shutdown process, improving operator responsiveness and reducing perceived delay while maintaining sufficient engine state for reliable restart through coordinated fuel injection and ignition timing.
Data Source
AI summary
A disclosed method of automatically stopping and restarting a vehicle engine determines if one or more stop/start enablement condition has been met. If the stop/start enablement condition or conditions have been met, the method initiates an engine shutdown. If a restart request is made before the engine comes to a complete stop, an intermittent engine restart is initiated.