Indirect Injection Engine Control for Wall Wetting
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Solution Overview
Problem
In spark-ignition, indirect-injection engines, the phenomenon of 'wall wetting' leads to a peak in fuel mixture richness when fuel injection stops, causing combustion degradation, increased pollutant emissions, and temporary engine torque issues, as residual fuel evaporates and mixes with reduced air flow.
Innovation Solution
The control method adjusts the fresh air intake valve to maintain the fuel mixture richness by accounting for residual fuel evaporation, using a feedback loop to regulate air flow based on the residual fuel flow, ensuring the mixture remains balanced and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fuel injection is stopped before the fresh air intake valve is completely closed to maintain richness equal to 1, then the mixture richness remains stable during accelerator release, but the residual fuel on walls evaporates and causes a richness peak leading to combustion deterioration and increased pollutant emissions
Solution Approach 1:
The control method stops fuel injection in advance before the fresh air intake valve is completely closed, taking into account the time delay caused by wall wetting. This preliminary action prevents the residual fuel from evaporating into the cylinder and causing richness peak and pollutant emissions, while maintaining mixture stability during the transition.
Solution Approach 2:
The control method applies a counteracting measure by stopping fuel injection before the valve closes, which anticipates and counteracts the harmful effect of residual fuel evaporation. This preliminary anti-action prevents the richness peak and associated combustion deterioration and pollutant emissions before they occur.
2Ease of operation
If fuel injection is stopped before the fresh air intake valve is completely closed, then the mixture richness is regulated by the valve, but the residual fuel evaporation creates a temporary richness peak causing non-zero engine torque that disturbs the driver
Solution Approach 1:
The control method stops fuel injection in advance before the fresh air intake valve is completely closed, anticipating the residual fuel evaporation that would otherwise cause a richness peak and temporary non-zero torque. This preliminary action ensures smooth deceleration and improves driver experience by eliminating disturbing torque fluctuations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces pollutant emissions and minimizes non-zero engine torque issues by maintaining a balanced fuel mixture, improving combustion efficiency and driver experience.
Implementation Method 1
the fuel film wetting the walls continues to slowly evaporate and supply the cylinders with fuel
Implementation Method 2
During fuel injection, most of the fuel evaporates instantly and is drawn into the cylinders
Data Source
Figure 1
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AI summary
The invention concerns a method for controlling an engine (1) with controlled ignition and indirect injection of a motor vehicle, which comprises: a) a step of determining the position of the accelerator pedal (30), then, in the case of complete release of the pedal, b) a step of partial closure of the intake valve (24) and of controlling the injectors, then, when the injectors (64) cease to inject the fuel, c) a step of determining a residual fuel flow entering into the combustion chamber, and d) a step of controlling the intake valve depending on the residual fuel flow so that the richness (λ) remains close to 1.