Internal Combustion Engine EGR Control for Stable Combustion
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Solution Overview
Problem
Existing control techniques for exhaust gas recirculation in internal combustion engines fail to promptly address unstable combustion, allowing it to persist for multiple cycles, leading to unfavorable fuel consumption and stability issues.
Innovation Solution
A control method that dynamically adjusts the exhaust gas recirculation rate based on real-time combustion stability indicators, allowing for immediate corrections when instability is detected, and prohibiting further increases until stability is restored, thereby preventing prolonged unstable combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the exhaust gas recirculation rate is increased to improve fuel consumption, then fuel efficiency is improved, but combustion stability deteriorates
Solution Approach 1:
The exhaust gas recirculation rate is dynamically adjusted based on real-time combustion stability detection. The control device increases the EGR rate when combustion is stable and decreases it immediately when instability is detected, creating a dynamic balance between fuel efficiency and combustion stability rather than using a fixed rate
Solution Approach 2:
A feedback mechanism is implemented where combustion stability is continuously monitored and used to control the exhaust gas recirculation rate. The detection device provides real-time information about combustion stability to the control device, which adjusts the EGR rate accordingly, creating a closed-loop control system
2Use of energy by moving object
If the exhaust gas recirculation rate is increased by a predetermined amount at every predetermined number of cycles, then fuel consumption is improved, but unstable combustion continues for a predetermined number of cycles
Solution Approach 1:
The control device performs preliminary actions by increasing the exhaust gas recirculation rate in advance when combustion stability is good, before instability occurs. This allows the system to reach optimal fuel efficiency points proactively rather than reactively, improving overall fuel consumption while maintaining stability
Solution Approach 2:
The feedback mechanism allows the control device to detect combustion instability and adjust the EGR rate in real-time, preventing the propagation of unstable combustion for a predetermined number of cycles. The continuous monitoring ensures that any instability is immediately addressed
3Stability of the object's composition
If the exhaust gas recirculation rate is decreased immediately when combustion stability drops, then unstable combustion is suppressed, but fuel efficiency deteriorates
Solution Approach 1:
The feedback control mechanism enables the system to respond appropriately to combustion stability changes. When instability is detected, the EGR rate is decreased to restore stability, and when stability is restored, the rate is increased again to improve fuel efficiency, creating a balanced control strategy
Solution Approach 2:
The exhaust gas recirculation rate is adjusted dynamically based on real-time combustion conditions. The control device continuously monitors stability and makes incremental adjustments to the EGR rate, allowing the system to optimize fuel efficiency while maintaining stability rather than using extreme corrections
Data Source
Figure 1
Figure 2
Figure 3(a)~3(d)
AI summary
An internal combustion engine (1) includes: an exhaust gas recirculation unit equipped with an exhaust gas recirculation control valve (9); a crank angle sensor (11) that detects an indicated mean effective pressure fluctuation rate (cPi) as an indicator of combustion stability of the internal combustion engine (1); and a controller (10) that corrects the EGR rate of the exhaust gas recirculation unit based on the combustion stability. The controller (10) is configured to: increase-correct the EGR rate by a predetermined amount when the state where the indicated mean effective pressure fluctuation rate (cPi) is lower than a threshold value continues for a predetermined number of cycles; and decrease-correct the EGR rate by a predetermined amount immediately when the indicated mean effective pressure fluctuation rate (cPi) is higher than or equal to the threshold value.