Four-Stroke Engine Exhaust Valve Timing for Filter Regeneration
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Solution Overview
Problem
Existing methods for regenerating particulate filters in exhaust gas aftertreatment systems of internal combustion engines do not effectively increase both exhaust gas temperature and NOx content, which are necessary for efficient filter regeneration, especially under low external load conditions.
Innovation Solution
A method of operating a four-stroke direct injection internal combustion engine that involves advancing the closing timing of the exhaust valve, performing fuel injections during both the compression and power strokes, and injecting additional fuel during the power stroke to enhance exhaust gas temperature and NOx content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine operates under low external load conditions, then fuel economy is improved, but exhaust gas temperature and NOx content are insufficient for effective particulate filter regeneration
Solution Approach 1:
Fuel is injected during the compression stroke before the power stroke begins, allowing combustion to start earlier in the cycle. This preliminary combustion action increases the temperature of the exhaust gas before it exits the cylinder, enabling filter regeneration even when the engine operates at low external load for fuel economy.
Solution Approach 2:
The invention changes the combustion parameters by injecting fuel at multiple stages (compression stroke and power stroke) and advancing the exhaust valve closing timing. These parameter changes increase both the temperature and NOx content of the exhaust gas, creating conditions suitable for particulate filter regeneration while maintaining low external load operation.
2Temperature
If the exhaust valve closing timing is advanced, then exhaust gas temperature is increased, but engine power output is reduced
Solution Approach 1:
The invention uses periodic multi-stage fuel injection actions during the compression and power strokes to compensate for the power loss caused by advanced exhaust valve closing. The periodic injection of fuel creates multiple combustion events that maintain engine power output while the advanced valve timing simultaneously increases exhaust gas temperature for filter regeneration.
Solution Approach 2:
By injecting fuel during the compression stroke before the power stroke, the invention creates preliminary combustion that increases exhaust temperature. This preliminary action allows the exhaust valve to close earlier while still maintaining sufficient combustion energy to preserve engine power output through the subsequent power stroke fuel injection.
3Quantity of substance
If multiple fuel injection steps are performed during compression and power strokes, then NOx content and exhaust temperature are increased for filter regeneration, but combustion control complexity increases
Solution Approach 1:
The fuel injection process is segmented into multiple distinct steps: injection during the compression stroke and additional injection during the power stroke. This segmentation allows precise control over the timing and amount of fuel injected at each stage, enabling independent optimization of NOx production and exhaust temperature while maintaining manageable control complexity through structured injection phases.
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 method achieves high NOx content and high temperature exhaust gas without external load on the engine, effectively supporting the regeneration of particulate filters in exhaust gas aftertreatment systems.
Implementation Method 1
a first fuel injecting step during a compression stroke of the piston... increase of NOx content in the exhaust gas is promoted
Implementation Method 2
fuel is injected into the combustion chamber, which fuel will not combust in the combustion chamber. Instead the fuel of the third injecting step is entrained with the exhaust gas for promoting exothermal reactions downstream of the exhaust valve and thus, for increasing the temperature of the exhaust gas
Data Source
Figure 1~2
Figure 3
Figure 4A~5
AI summary
Herein a four-stroke direct injection ICE (4) is disclosed. The ICE comprises a camshaft (10), and exhaust valve (16), and a control system (42). The control system (42) is configured to: - change the timing of the camshaft (10) to advance a closing of the exhaust valve (16), - control a first fuel injecting step (62) during a compression stroke of the piston (20), - control a second fuel injecting step (64) during a power stroke of the piston (20), and - control a third fuel injecting step (66), after the second fuel injecting step (64), during the power stroke of the piston (20).