Idle Stop Control Using Time-Temperature Logic
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Solution Overview
Problem
The variability in the timing of engine stoppage in idle stop vehicles due to factors like transmission oil temperature changes causes inconsistency and discomfort for drivers, as the engine may stop either immediately or after a prolonged period after the vehicle has stopped.
Innovation Solution
An idle stop vehicle system that includes an idle stop condition determination unit and an engine control unit, which determines whether the idle stop conditions are met before a specified time and prohibits the idle stop if these conditions are not met, ensuring consistent engine stoppage timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the idle stop condition is determined based on transmission oil temperature entering a permitted range, then the engine can automatically stop to improve fuel economy, but the period until the engine automatically stops varies significantly causing driver discomfort
Solution Approach 1:
The control unit starts counting stoppage time from the moment the vehicle stops, before the idle stop condition is fully determined. This preliminary timing action allows the system to proactively manage the idle stop decision based on both the elapsed time and the eventual satisfaction of temperature conditions, rather than passively waiting for the oil temperature to enter the permitted range.
Solution Approach 2:
The system dynamically adjusts the idle stop decision by combining two criteria: (1) whether the idle stop condition holds (transmission oil temperature in permitted range) and (2) whether the stoppage time exceeds a predetermined threshold. This dynamic evaluation allows the engine to stop promptly when conditions are favorable while preventing excessive delays when temperature conditions are not met, thereby maintaining driver comfort.
2Reliability
If the engine automatically stops only when transmission oil temperature enters the permitted range, then proper lubrication is ensured, but the stoppage time becomes unpredictable and inconsistent
Solution Approach 1:
The control unit initiates a stoppage time counter as a preliminary action when the vehicle stops, regardless of whether the transmission oil temperature has entered the permitted range. This allows the system to establish a time baseline before making the final idle stop decision, enabling consistent and predictable stoppage timing.
Solution Approach 2:
The system changes the decision parameters for idle stop from solely temperature-based to a combined time-temperature evaluation. By introducing stoppage time as a critical parameter with a predetermined threshold, the system ensures that the engine stops within a consistent time frame while still maintaining the temperature requirement for proper lubrication.
Data Source
AI summary
An idle stop vehicle performs an idle stop to automatically stop an engine during a stop of the vehicle. The vehicle includes an idle stop condition determination unit for determining whether or not an idle stop condition holds, and an engine control unit for performing the idle stop when the idle stop condition holds before a stoppage time exceeds a specified time and prohibiting the idle stop after the stoppage time exceeds the specified time without the idle stop condition holding.