Oxygen Concentration Calculation in Combustion Chamber
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Solution Overview
Problem
In internal combustion engines, inaccurate control of oxygen concentration and internal EGR amount leads to increased nitrogen oxide (NOx) emissions during acceleration driving, especially when exhaust gas is reintroduced using variable valve lift and EGR devices.
Innovation Solution
A method for calculating oxygen concentration in a combustion chamber, involving calculations of volume efficiency, mass of internal EGR, and oxygen mass using engine speed, manifold pressures, and temperature, to accurately predict internal and high-pressure EGR amounts, thereby controlling intake air and boost pressure for reduced NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If exhaust gas is reintroduced into the combustion chamber using variable valve lift and EGR device, then nitrogen oxide emissions are reduced, but oxygen concentration control becomes inaccurate during acceleration driving
Solution Approach 1:
The patent implements feedback control by continuously monitoring oxygen concentration in the combustion chamber and using this information to adjust the EGR valve opening degree and variable valve lift timing. This closed-loop control system ensures accurate oxygen concentration control despite the complex interactions between exhaust gas recirculation and combustion processes during acceleration driving.
Solution Approach 2:
The patent dynamically adjusts multiple parameters including EGR rate, valve lift timing, intake air amount, and boost pressure based on real-time oxygen concentration measurements and engine operating conditions. This multi-parameter optimization enables accurate control of oxygen concentration while maintaining reduced NOx emissions through coordinated adjustment of these variables.
2Productivity
If internal EGR amount and oxygen concentration are not accurately controlled, then nitrogen oxide increases during acceleration driving
Solution Approach 1:
The patent performs preliminary calculations of the required intake air amount and boost pressure based on target oxygen concentration and detected engine parameters before actual combustion occurs. This advance preparation ensures that when acceleration is demanded, the correct air-fuel mixture and EGR rate are already in place, enabling both strong acceleration performance and low NOx emissions.
Solution Approach 2:
The patent replaces traditional mechanical EGR control systems with an electronically controlled system that uses sensors, processors, and actuators to precisely regulate exhaust gas recirculation. This substitution enables dynamic adjustment of EGR rate and oxygen concentration based on real-time engine conditions, achieving both acceleration performance and emission reduction that mechanical systems cannot accomplish.
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
The method accurately calculates oxygen concentration and internal EGR amount, allowing for precise control of intake air and boost pressure, which reduces nitrogen oxide emissions.
Implementation Method 1
The mass of the internal EGR may be calculated from an equation of Pa*V/(R*Te), where, Pa represents the pressure of the exhaust manifold, V represents the volume of the internal EGR, R represents a gas constant, and Te represents the temperature of the exhaust manifold
Data Source
AI summary
Provided is a method for calculating an oxygen concentration in a combustion chamber, including: calculating volume efficiency of the combustion chamber while a variable valve lift is in an on state and the volume efficiency of the combustion chamber and the volume of internal EGR from the volume of the combustion chamber while the variable valve lift is in an off state; and calculating a mass of the internal EGR from the pressure of an exhaust manifold, the temperature of the exhaust manifold, and the volume of the internal EGR.