Intake Manifold Oxygen Control Algorithm for Diesel EGR
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Solution Overview
Problem
Existing diesel engine control systems fail to accurately control excess oxygen levels during combustion, which limits further emission reduction and engine efficiency improvements, as they do not account for the variable oxygen content in exhaust gas recirculation (EGR).
Innovation Solution
An engine control algorithm that calculates and controls the precise amounts of EGR and fresh air delivered to the intake manifold, taking into account the oxygen content in both, to maintain optimal oxygen ratios for reduced emissions and enhanced efficiency, by measuring and adjusting the mass flow rates of oxygen from fresh air and EGR gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional EGR control strategies are used that do not account for variable oxygen content in EGR gas, then the control system is simpler to implement, but the precision of oxygen level control during combustion deteriorates
Solution Approach 1:
The control algorithm dynamically adjusts the EGR oxygen content parameter based on operating conditions. The system calculates the actual oxygen content in EGR gas using the formula: O2_EGR = O2_intake - 3.51×fuel_rate, and uses this variable parameter to precisely control the oxygen level in the intake manifold, resolving the contradiction between control precision and system complexity.
2Object-generated harmful factors
If the EGR valve is controlled to maximize exhaust gas recirculation, then NOx emissions are reduced, but the oxygen availability for combustion deteriorates
Solution Approach 1:
The control system implements feedback by continuously monitoring the oxygen content in the intake manifold and adjusting the EGR valve position accordingly. The algorithm calculates the required fresh air mass flow rate based on the desired oxygen level and actual EGR oxygen content, ensuring that NOx emissions are reduced while maintaining adequate oxygen availability for complete combustion.
3Productivity
If the control system accounts for variable oxygen content in EGR gas, then emission reduction and engine efficiency are improved, but the calculation and control complexity increases
Solution Approach 1:
The control algorithm performs preliminary calculations of EGR oxygen content based on the intake oxygen level and fuel injection rate before controlling the EGR valve. By pre-calculating the oxygen balance equation (O2_EGR = O2_intake - 3.51×fuel_rate) and using these pre-computed values for control decisions, the system achieves improved engine efficiency while managing calculation complexity through structured pre-processing.
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 algorithm effectively maintains optimal oxygen ratios, reducing emissions and improving engine efficiency by precisely controlling the oxygen contribution from both fresh air and EGR, even during transient conditions, thereby enhancing compliance with emission regulations.
Implementation Method 1
calculates and controls the precise amounts of EGR and fresh air delivered to the intake manifold, taking into account the oxygen content in both, to maintain optimal oxygen ratios
Implementation Method 2
The mass flow rate of recirculated exhaust gas that mixes with the fresh air entering the intake system
Data Source
AI summary
A method for controlling intake manifold oxygen for an engine having a fresh air inlet and an exhaust gas recirculation (EGR) circuit includes the steps of: establishing an ideal excess oxygen ratio for combustion in the engine; calculating a total mass flow of oxygen to be delivered to an intake manifold of the engine to maintain the ideal excess oxygen ratio; determining a mass flow of EGR oxygen in the mass flow of EGR gas; and controlling a desired mass flow of fresh oxygen to be delivered to the intake manifold such that the sum of the desired mass flow of fresh oxygen and the mass flow of EGR oxygen is equal to the desired total mass flow of oxygen, by re-adjusting the EGR valve.