Engine ECU Fuel Injection Control for Cold Start Stability
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Solution Overview
Problem
Existing fuel injection control devices for internal combustion engines fail to accurately correct fuel injection amounts, especially during cold starts, leading to unstable air-fuel ratios and potential misfire, due to inappropriate learning values and lack of consideration for increased fuel injection needs.
Innovation Solution
A control device that selectively controls fuel injection between in-cylinder and intake manifold injectors based on engine temperature, prohibiting correction calculations during cranking and idling phases and permitting them after full combustion, ensuring stable air-fuel ratios and accurate learning values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel injection amount is increased during cold start to improve starting capability, then starting capability is improved, but air-fuel ratio becomes unstable and correction accuracy deteriorates
Solution Approach 1:
The system performs preliminary classification of operational states before executing correction calculations. By pre-defining cold start conditions as a distinct state where correction is prohibited, the system prepares the correction mechanism in advance to avoid inaccurate calculations during transient fuel injection increases, thus resolving the contradiction between improved starting capability and maintained correction accuracy.
2Measurement precision
If correction calculation is performed during all operating conditions, then correction accuracy is maintained, but inappropriate corrections occur during cold start
Solution Approach 1:
The system applies different correction strategies to different operational states. During cold start conditions, correction calculation is prohibited, while during normal operating conditions, correction calculation is permitted. This localized differentiation ensures that correction accuracy is maintained where applicable while avoiding inappropriate corrections during cold start, resolving the contradiction between maintaining correction accuracy and ensuring correction appropriateness.
3Productivity
If learning value is calculated during transient fuel injection increase, then learning speed is improved, but learning accuracy deteriorates due to unstable air-fuel ratio
Solution Approach 1:
The system preemptively prevents learning value calculation during cold start conditions when air-fuel ratio is unstable. By prohibiting learning calculations during these transient periods, the system counteracts the potential for inaccurate learning before it can occur, thus resolving the contradiction between learning speed and learning accuracy by sacrificing temporary learning opportunities to ensure overall learning quality.
Data Source
AI summary
An engine ECU executes a program including the steps of: starting an engine by transiently increasing an amount of fuel injection when a start request is detected; prohibiting calculation of a learn value when a condition for stopping transient increase is not satisfied; stopping transient increase when the condition for stopping transient increase is satisfied; steadily increasing the amount of fuel injection in accordance with a coolant temperature TW; and permitting calculation of a learn value during steady increase in accordance with the coolant temperature TW.