Tracer Gas Mixture Richness Estimation in Engine Intake
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Solution Overview
Problem
The challenge in controlling internal combustion engines, particularly two-stroke engines, lies in accurately determining the richness of the gas mixture in the combustion chamber due to scavenging phenomena, which affects fuel consumption and pollutant emissions, as traditional methods like exhaust gas analysis are unreliable and sampling is impractical in mass-produced engines.
Innovation Solution
A system and method that injects an additional combustible gas into the fresh-air intake circuit, measures its concentration in both intake and exhaust circuits, calculates a ratio to estimate the richness of the gas mixture, and further estimates the flow rate of residual gases to optimize engine control and emission management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional exhaust gas analysis is used to determine richness, then the measurement is simple to perform, but the measurement precision is poor due to scavenging phenomenon diluting the exhaust gases
Solution Approach 1:
The patent introduces an additional combustible gas as an intermediary tracer substance. This gas is injected into the fresh air intake circuit and serves as a marker to track the actual amount of fresh air reaching the combustion chamber. By measuring the concentration ratio of this tracer gas between intake and exhaust, the system can precisely determine the enclosed air amount and richness without being affected by the scavenging dilution that plagues traditional exhaust analysis methods.
2Measurement precision
If gas sampling in the combustion chamber is performed to accurately measure fresh air and residual gases, then the measurement precision would be high, but the device complexity and manufacturing cost become unacceptable for mass-produced engines
Solution Approach 1:
The system utilizes the engine's own exhaust manifold and intake manifold as measurement locations, eliminating the need for intrusive combustion chamber sampling. The additional combustible gas tracer method allows the existing engine components to serve the dual purpose of their original function plus measurement, avoiding complex sampling systems while achieving precise determination of fresh air and residual gas amounts.
3Power
If the amount of fuel is increased to compensate for uncertain richness conditions, then the engine torque can be maintained, but the polluting emissions particularly soot increase rapidly
Solution Approach 1:
The system implements closed-loop feedback control by continuously measuring the concentration of the additional combustible gas in the exhaust and using this information to accurately determine the actual richness in the combustion chamber. This precise feedback allows the control system to adjust fuel injection amount optimally, maintaining the desired torque while avoiding excessive fuel injection that would lead to soot formation. The feedback mechanism enables real-time optimization of the fuel-air ratio based on actual combustion chamber conditions.
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 approach allows for precise control of fuel consumption and pollutant emissions by accurately estimating the gas mixture richness, reducing the risk of excessive soot and nitrogen oxides, and is adaptable to both two-stroke and four-stroke engines.
Implementation Method 1
an amount of additional combustible gas is injected into a fresh-air intake circuit of the engine... measuring means for measuring concentrations of the additional gas respectively in the fresh-air intake circuit and in a gas-exhaust circuit
Data Source
AI summary
A system for estimating richness of a gaseous mixture in a combustion chamber of an internal combustion engine of a motor vehicle power plant, including a mechanism injecting an additional combustible gas into a fresh air intake circuit of the engine, a mechanism measuring concentrations of the additional gas in the fresh air intake circuit and in an engine exhaust gas circuit respectively, a mechanism determining a ratio between the measured concentration of the additional gas in the intake circuit and the measured concentration of the additional gas in the exhaust circuit, and a mechanism estimating the richness of the gaseous mixture in the combustion chamber of the engine from the determined ratio.