Engine Intake Air Amount Control for Startup Emission Reduction
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Solution Overview
Problem
Existing engine systems experience excessive fuel injection at startup, leading to emission deterioration when the engine is restarted before the intake system pressure reaches atmospheric pressure, causing an overestimation of intake air amount and subsequent fuel injection.
Innovation Solution
Incorporating an intake pressure sensor and an electronic control unit that uses an initial value of the intake air amount model based on intake pressure detection when the engine rotational speed is below a specified threshold at startup, instead of relying solely on atmospheric pressure learning, to accurately calculate the intake air amount and prevent excessive fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If atmospheric pressure learning is used for fuel injection control, then fuel injection control can be performed based on learned intake air amount, but excessive fuel injection occurs when engine is started before intake system pressure reaches atmospheric pressure
Solution Approach 1:
The system dynamically switches between two different intake air amount models based on engine operating conditions. When engine rotational speed is below a specified threshold at startup, the system uses an intake pressure-based model; when rotational speed exceeds the threshold, it transitions to the atmospheric pressure learning-based model. This dynamic adaptation resolves the contradiction by ensuring reliable emission control across varying operating conditions while maintaining automated control.
Solution Approach 2:
The system changes the parameter used for intake air amount calculation based on engine state. At low rotational speeds during startup, it uses intake pressure as the basis for calculation; at higher rotational speeds, it switches to using atmospheric pressure learning results. This parameter change approach allows the system to maintain accurate fuel injection control and prevent excessive fuel injection during critical startup phases while benefiting from automated control during stable operation.
2Measurement precision
If intake pressure sensor is added to improve intake air amount calculation accuracy, then excessive fuel injection is suppressed, but device complexity increases
Solution Approach 1:
The system applies the intake pressure sensor selectively rather than continuously. The sensor data is used only during specific conditions (low rotational speed startup phases), while atmospheric pressure learning handles the majority of operating conditions. This partial application approach improves measurement precision when most needed without fully committing to a more complex sensor-based system for all operations, thus balancing accuracy improvement with device complexity.
Data Source
AI summary
An engine system includes an engine, an atmospheric pressure sensor, an intake pressure sensor, and an electronic control unit. The electronic control unit is configured to execute atmospheric pressure learning for learning a relation between atmospheric pressure and an intake air amount of the engine based on the atmospheric pressure detected by the atmospheric pressure sensor, and execute fuel injection control of the engine using an initial value of an intake air amount model obtained based on the atmospheric pressure learning. The electronic control unit is configured to execute the fuel injection control of the engine using an initial value of the intake air amount model obtained based on the intake pressure detected by the intake pressure sensor, when rotational speed of the engine is less than a specified rotational speed at start of the fuel injection control of the engine.