Engine Idling Stop Control for Coasting and Stop-Go Drivability
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Solution Overview
Problem
Existing engine control systems face challenges in maintaining drivability and fuel efficiency, particularly during frequent stop-and-go traffic conditions where engine idling stops and restarts are frequent, leading to increased stop-restart cycles and decreased fuel efficiency.
Innovation Solution
An engine control unit that automatically stops the engine only when the vehicle is stationary and the speed exceeds a predetermined first speed, and during coasting if the speed exceeds a second speed but falls below a third speed, thereby preventing frequent idling stops and optimizing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is automatically stopped while the vehicle is coasting at a speed below the engine-stop permission speed, then the frequency of automatic stops increases to improve fuel efficiency, but the frequency of stop-restart cycles increases when the vehicle runs at variable speeds approximating the engine-stop speed and engine-stop permission speed, which impairs drivability
Solution Approach 1:
The patent applies dynamics by making the engine-stop permission speed variable rather than fixed. The control unit adjusts the engine-stop permission speed based on the vehicle's running state: setting it to a first higher value during stationary-state (stop-and-go traffic) and a second lower value during coasting-state. This dynamic adjustment allows the system to optimize fuel efficiency during coasting while preventing frequent stop-restart cycles during stationary-state, thereby resolving the contradiction between fuel efficiency and drivability
Solution Approach 2:
The patent changes the parameter of engine-stop permission speed based on different vehicle operating conditions. By detecting whether the vehicle is in stationary-state or coasting-state and adjusting the permission speed accordingly, the system adapts the stop criteria to match the driving context. This parameter change enables frequent stops during coasting (improving fuel efficiency) while preventing frequent stops during stationary-state (maintaining drivability)
2Ease of operation
If a single engine-stop permission speed is used to prevent frequent stop-restart cycles during stationary-state, then drivability is maintained, but the frequency of automatic stops during coasting decreases, reducing fuel efficiency improvement
Solution Approach 1:
The patent segments the driving conditions into two distinct states: stationary-state and coasting-state. Each state has its own engine-stop permission speed threshold. During stationary-state, a higher permission speed prevents frequent stops, while during coasting-state, a lower permission speed enables frequent stops to improve fuel efficiency. This segmentation allows the system to optimize for different objectives under different conditions, resolving the contradiction between drivability and fuel efficiency
3Loss of energy
If the engine-stop permission speed is set low to increase automatic stop frequency, then fuel efficiency improves, but frequent stop-restart cycles occur during traffic jam or parking operation, impairing drivability
Solution Approach 1:
The system dynamically adjusts the engine-stop permission speed based on the detected vehicle state. During coasting-state, the permission speed is set to a lower second value to increase automatic stop frequency and improve fuel efficiency. During stationary-state, the permission speed is set to a higher first value to prevent frequent stop-restart cycles and maintain drivability. This dynamic adaptation resolves the contradiction by applying different speed thresholds for different operating contexts
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A stationary-state idling stop controller (10) carries out a stationary-state idling stop to automatically stop an engine (2) upon the establishment of a stationary-state idling stop condition including the stop of a vehicle after a speed (V) detected by a speed sensor (4) exceeds a first speed, and a coasting-state idling stop controller (20) carries out a coasting-state idling stop to automatically stop the engine (2) during a coasting state of the vehicle upon the establishment of a coasting-state idling stop condition including the detection of a speed (V) by the speed sensor (4) exceeding a second speed higher than the first speed and then falling below a third speed lower than the second speed.