Internal Combustion Engine Exhaust Pressure Pulse Residual Gas Control
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Solution Overview
Problem
Internal combustion engines face challenges in raising nitrogen oxide conversion rates in SCR catalytic converters, especially under low load conditions, due to insufficient exhaust gas temperatures, which conventional methods like valve overlap and residual gas recirculation struggle to address without impacting engine performance.
Innovation Solution
A method involving the creation of pressure pulses in the exhaust line to recirculate residual exhaust gas into the combustion chamber during the inlet stroke, using phase offsets and valve timing adjustments to increase exhaust gas temperature without affecting full-load performance, thereby enhancing nitrogen oxide conversion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If valve overlap is increased to raise exhaust gas temperature and nitrogen oxide conversion rates, then exhaust gas temperature improves, but residual gas rate increases which negatively affects consumption
Solution Approach 1:
The patent employs periodic pressure pulses generated by exhaust valve opening in a first cylinder during its exhaust stroke. These pulses are timed to coincide with the exhaust stroke of a second cylinder, creating periodic pressure variations that drive residual gas from the second cylinder into the inlet passage and subsequently into the combustion chamber during the inlet stroke, achieving temperature control without increasing valve overlap
Solution Approach 2:
The system utilizes the engine's own exhaust gas and existing pressure pulsations from normal operation to achieve the desired effect. The residual gas already present in the combustion chamber is redirected through the inlet passage back into the combustion chamber during the inlet stroke, eliminating the need for external heating systems or increased valve overlap
2Reliability
If internal exhaust gas recirculation is used to improve emissions across all engine speed ranges, then nitrogen oxide conversion improves, but charge exchange work is reduced
Solution Approach 1:
The system dynamically adjusts residual gas recirculation based on engine operating conditions. By utilizing pressure pulses that naturally occur during specific stroke sequences and cylinder phases, the method provides adaptive residual gas control that responds to changing engine loads and speeds without requiring fixed geometric modifications or continuous active control
Solution Approach 2:
The patent divides the residual gas recirculation process into distinct phases: pressure pulse generation during exhaust stroke, gas transfer through inlet passage, and final delivery to combustion chamber during inlet stroke. This segmentation allows precise control over when and how residual gas is recirculated, optimizing both emissions control and charge exchange efficiency
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 effectively raises exhaust gas temperature under low load conditions, improving nitrogen oxide conversion rates in SCR catalytic converters while maintaining engine torque and charge exchange efficiency.
Implementation Method 1
feeding exhaust gas from a combustion chamber of a cylinder into an inlet passage of the cylinder during an exhaust stroke of the cylinder by means of propagation of the pressure pulse from the exhaust line into the combustion chamber of the cylinder
Implementation Method 2
feeding the exhaust gas from the inlet passage of the cylinder into the combustion chamber of the cylinder during an inlet stroke of the cylinder
Data Source
AI summary
The present disclosure relates to a method for operating an internal combustion engine (IO). The method includes generating a pressure pulse in an exhaust gas system of the internal combustion engine (IO). The method also includes supplying exhaust gas from a combustion chamber of a cylinder during an exhaust outlet stroke of the cylinder into an inlet channel of the cylinder by propagating the pressure pulse from the exhaust gas system into the combustion chamber of the cylinder. The method further includes supplying the exhaust gas from the inlet channel of the cylinder into the combustion chamber of the cylinder during an intake stroke of the cylinder. By means of internal residual gas control (residual exhaust gas control), the method permits the exhaust gas temperature to be raised in at low load without negatively influencing the full load performance of the internal combustion engine (IO).