Engine Blow-Through Air Determination and Compensation
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Solution Overview
Problem
Existing engine systems face challenges in accurately accounting for cylinder blow-through, which affects engine emissions and catalyst balance, making it difficult to maintain optimal air-fuel ratios and engine power output.
Innovation Solution
A method is developed to determine cylinder blow-through by adjusting engine actuators based on the difference between total cylinder air mass flow and volumetric efficiency curves, allowing for precise control of air-fuel ratios and emissions management without requiring complex calculations or determining the cylinder air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If blow-through is increased to evacuate exhaust residuals and increase engine power, then engine power output increases, but oxygen balance in the catalyst is upset and NOx conversion efficiency decreases
Solution Approach 1:
The system uses feedback from oxygen sensors (pre-cat and post-cat) to continuously monitor oxygen levels in the exhaust stream. This feedback enables the ECU to dynamically adjust fuel injection and blow-through air management to maintain optimal catalyst operation while maximizing engine power output.
Solution Approach 2:
The system dynamically changes operational parameters including fuel injection timing, injection duration, and intake valve timing to control the amount of blow-through air. By adjusting these parameters, the system can evacuate exhaust residuals for power enhancement while maintaining proper oxygen balance for catalyst efficiency.
2Quantity of substance
If air-fuel ratio is richened to compensate for blow-through, then average stoichiometric mixture is achieved, but it is difficult to maintain catalyst balance without knowing blow-through amount
Solution Approach 1:
The system uses the catalyst's own oxygen storage capacity as a sensor to indirectly measure blow-through air amount. The oxygen differential across the catalyst provides self-service feedback that eliminates the need for complex direct measurements or additional sensors to determine blow-through quantity.
Solution Approach 2:
The catalyst acts as an intermediary that transforms the unmeasured blow-through air into a measurable oxygen differential signal. This intermediary mechanism allows the system to infer blow-through amount and adjust fueling without requiring direct measurement of the blow-through air itself.
3Ease of manufacture
If blow-through is used to promote regeneration of exhaust gas emissions device, then carbonaceous soot is oxidized, but excess blow-through may supply excessive oxygen to the catalyst
Solution Approach 1:
The system dynamically adjusts blow-through air management and fuel injection in real-time based on catalyst oxygen storage state and regeneration requirements. This dynamic control allows the system to supply sufficient oxygen for soot oxidation while preventing excessive oxygen that would harm NOx conversion efficiency.
Data Source
AI summary
A method for determining cylinder blow-through air via engine volumetric efficiency is disclosed. In one example, the method provides a way to adjust cylinder blow-through to promote and control a reaction in an exhaust after treatment device. The approach may simplify cylinder blow-through calculations and improve engine emissions via providing improved control of constituents reaching an exhaust after treatment device.