Preventing Engine Shutdown After Tow-Start Detection
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Solution Overview
Problem
Existing automatic start-stop systems for internal combustion engines in vehicles may inadvertently switch off the engine when a restart is not feasible, leading to customer complaints and potential breakdowns, especially if the starting system is defective or the battery is low.
Innovation Solution
The method prevents automatic shutdown of the internal combustion engine by detecting a tow-start process, which involves deactivating the automatic start-stop system's shutdown function and recognizing a successful start through crankshaft speed analysis and starter unit activity, ensuring the engine remains operational until a manual shutdown occurs or a predetermined number of successful tow-starts are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the automatic start-stop system is activated to reduce fuel consumption and emissions, then fuel efficiency is improved, but the risk of unintended engine shutdown increases when restart is not feasible
Solution Approach 1:
The system performs preliminary detection of starter unit activity and tow-start conditions before allowing automatic shutdown. By detecting whether the starter unit is active or inactive during the starting process, the system proactively identifies situations where restart may not be feasible, and prevents automatic shutdown before it occurs, thus maintaining engine reliability while preserving fuel savings in normal conditions
Solution Approach 2:
The system continuously monitors feedback signals from the starter unit and starting system to determine current operational status. By evaluating the activity state of the starter unit during starting processes and using this feedback to control the automatic shutdown function, the system adapts its behavior based on real-time system conditions, preventing shutdown when restart is not possible while maintaining automatic shutdown capability when conditions are favorable
2Reliability
If the automatic shutdown function is prevented from operating to avoid breakdowns, then reliability is improved, but fuel consumption increases
Solution Approach 1:
The system applies different operational characteristics to different starting scenarios. Instead of universally disabling automatic shutdown, it selectively activates the prevention function only when tow-start conditions are detected (indicated by inactive starter unit during starting). In normal starting conditions, the automatic shutdown function operates as intended, thus maintaining fuel efficiency while providing reliability protection only where needed
3Reliability
If the system continuously monitors starting conditions to prevent unintended shutdown, then reliability is improved, but system complexity increases
Solution Approach 1:
The system utilizes existing sensors and control components already present in the vehicle's starting system, specifically the starter unit activity signals and existing detection infrastructure. By repurposing these existing elements to detect tow-start conditions and control automatic shutdown, the system achieves improved reliability without adding significant new hardware or complex subsystems, thus minimizing the increase in overall system complexity
Data Source
AI summary
The invention relates to a method for controlling an automatic switching off process for an internal combustion engine in a motor vehicle, wherein, depending on given operating conditions, an automatic switching off of the internal combustion engine is prevented. According to the invention, an automatic switching off of the internal combustion engine is prevented if the internal combustion engine has been started by towing within the given operating cycle or within a given number of previous operating cycles. A tow-start is recognised by analysis of a signal giving the activity or non-activity of the starter.