Engine Start-Stop Control Using Range and Range-Rate Signals
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Solution Overview
Problem
Existing vehicle systems struggle to accurately anticipate a driver's power demands, leading to inefficient engine startups and shutdowns, which can result in fuel economy and emissions issues due to false positives from minor movements of preceding vehicles.
Innovation Solution
A vehicle system utilizing sensors to generate range and range-rate signals, processed by a device to determine if a preceding vehicle is moving away, with a predetermined envelope to differentiate actual movement from minor stops, thereby optimizing engine operation based on these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is restarted whenever the preceding vehicle moves, then the system responds quickly to potential power demands, but false positives from minor movements cause unnecessary engine startups reducing fuel economy
Solution Approach 1:
The system performs preliminary analysis of the preceding vehicle's movement characteristics (acceleration, duration, distance) before triggering engine restart. This preliminary evaluation distinguishes between significant movements indicating upcoming power demands and minor movements that are unlikely to require immediate engine restart, thereby reducing false positives while maintaining quick response to genuine demands
Solution Approach 2:
The system changes the parameters used for movement detection by considering multiple factors simultaneously (acceleration rate, movement duration, distance traveled) rather than relying on a single threshold. This multi-parameter approach enables more accurate differentiation between meaningful movements and false positives, optimizing the balance between response speed and fuel economy
2Reliability
If the engine runs continuously to ensure immediate power availability, then power demand is always met, but fuel economy and emissions are degraded
Solution Approach 1:
The system performs preliminary assessment of power demand likelihood by analyzing preceding vehicle movement patterns before shutting down the engine. When movement patterns suggest imminent power demand, the engine remains running or restarts immediately, ensuring reliability. When patterns indicate no imminent demand, the engine can be shut down to save fuel, thus balancing reliability and fuel consumption
3Loss of energy
If the engine is shut off at every stop to maximize fuel economy, then fuel efficiency improves, but unnecessary restarts occur reducing overall efficiency
Solution Approach 1:
The system changes from a simple on/off control based on vehicle stop to a multi-parameter decision system that evaluates acceleration, movement duration, and distance. This enables intelligent determination of whether engine shutdown is appropriate, maximizing fuel economy when safe to do so while maintaining overall system efficiency by avoiding unnecessary restarts and ensuring power availability when needed
Data Source
AI summary
A vehicle system having at least one sensor configured to output a range signal and a range-rate signal. The range signal represents a distance from a host vehicle to the front vehicle and the range-rate signal represents range-rate information of the front vehicle relative to the host vehicle. A processing device is configured to output a control signal based on the range signal and the range-rate signal. The control signal commands an engine of the host vehicle to start.