EGR Control Apparatus Combustion Stop Delay for Engine Restart Stability
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Solution Overview
Problem
In internal combustion engines with EGR devices, combustion stop control operations like fuel cut and idle reduction can lead to unstable engine restart due to excessive EGR gas flowing into the cylinder, as existing techniques fail to accurately determine and reduce the cylinder-inflow EGR gas quantity.
Innovation Solution
A control apparatus with a combustion stop delay control arrangement that estimates and senses the cylinder-inflow EGR gas quantity, delaying the combustion stop operation if the quantity exceeds a normal combustion threshold, ensuring stable engine restart by reducing EGR gas flow into the cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If combustion stop control operation is executed to stop engine combustion, then fuel consumption is reduced and emissions are decreased, but excessive EGR gas flows into the cylinder at restart causing unstable combustion
Solution Approach 1:
The control apparatus performs preliminary actions by closing the EGR valve before the combustion stop control operation is executed. This preliminary closure of the EGR valve prevents excessive EGR gas from flowing into the cylinder during engine restart, thereby maintaining combustion stability while still allowing the combustion stop operation to reduce fuel consumption and emissions.
2Reliability
If EGR valve is closed to reduce EGR gas quantity, then combustion stability at restart is improved, but EGR gas remains in intake passage causing potential instability
Solution Approach 1:
The control apparatus executes preliminary action by closing the EGR valve before the combustion stop control operation. This timing ensures that the EGR gas quantity in the intake passage is reduced to a safe level before restart, preventing combustion instability while maintaining the benefits of the combustion stop operation for fuel economy.
3Reliability
If combustion stop control is delayed to reduce EGR gas quantity, then restartability is improved, but engine stop time is extended
Solution Approach 1:
The control apparatus closes the EGR valve in advance before the combustion stop control operation is executed. This preliminary action reduces the EGR gas quantity in the intake passage, allowing the combustion stop operation to be executed promptly without excessive delay, thus improving restartability while minimizing the extension of engine stop time.
Data Source
AI summary
EGR gas quantity information, which indicates a quantity of the EGR gas flowing into a cylinder of an internal combustion engine, is obtained by an ECU. A combustion stop delay control operation, which delays execution of a combustion stop control operation, is executed by the ECU when the quantity of the EGR gas flowing into the cylinder is larger than a normal combustion determination threshold value. When the quantity of the EGR gas flowing into the cylinder becomes equal to or smaller than the normal combustion determination threshold value, the combustion stop control operation is enabled by the ECU.