Dynamic Engine Stop Threshold Based on Deceleration
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Solution Overview
Problem
Conventional engine automatic control devices restart the engine against the driver's intention while driving at reduced speeds, leading to inefficient mileage due to fixed engine start thresholds that do not account for deceleration, resulting in unnecessary engine restarts and potential discomfort.
Innovation Solution
A vehicle engine automatic control device that detects the amount of brake operation and sets dynamic thresholds for engine stop and restart based on deceleration, using a brake operation amount detecting means and threshold setting means to adjust the engine start and stop conditions, ensuring the engine is stopped when the brake operation is within a predetermined range and restarted when it falls below a lower limit threshold, while avoiding unnecessary restarts during deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the engine start determination threshold is fixed regardless of deceleration, then the control logic is simple, but the engine may be re-started against the driver's intention during reduced speed driving, reducing mileage improvement
Solution Approach 1:
The engine start determination threshold is changed from a fixed value to a dynamic value that varies with deceleration. The threshold is set lower when deceleration is high and higher when deceleration is low, allowing the system to adapt to different driving conditions and prevent unnecessary engine restarts during smooth deceleration phases
Solution Approach 2:
The threshold parameter for engine start determination is modified based on the deceleration parameter. By changing the threshold value according to deceleration levels, the system optimizes the balance between fuel efficiency and driver intention, preventing premature engine restarts during low-deceleration periods
2Loss of energy
If the engine start determination threshold is set low to improve mileage, then fuel efficiency increases, but the engine may fail to restart timely when the driver intends to accelerate
Solution Approach 1:
The threshold dynamically adjusts based on deceleration conditions, being lower during high deceleration (improving fuel efficiency) and higher during low deceleration (ensuring timely restart when acceleration is needed), thus resolving the contradiction between fuel efficiency and response speed
Solution Approach 2:
The system continuously monitors deceleration and uses this feedback to adjust the engine start threshold in real-time, ensuring the threshold is appropriate for the current driving condition and preventing both premature and delayed engine restarts
Data Source
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AI summary
A vehicle engine automatic control device has a brake operation amount detecting means configured to detect the amount of brake operation by the driver, an engine stopping/re-starting means configured to stop the engine when the amount of brake operation that is detected exceeds the first threshold during coast drive, and re-start the engine when the amount of brake operation that is detected becomes equal to or lower than the first threshold after the engine stops, and a threshold setting means configured to set the first threshold smaller as the deceleration lowers.