Exhaust Gas Recirculation Control via Turbocharger Speed and Lambda
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current exhaust-gas recirculation systems for turbocharged internal combustion engines face stability issues and increased fuel consumption due to reliance on mass air flow measurements, which are prone to durability problems and fluctuations, and require costly oxygen sensor upgrades for accurate NOx emission control.
Innovation Solution
The system uses a turbocharger speed and exhaust-gas lambda sensor to calculate and control the exhaust-gas recirculation rate, eliminating the need for unreliable mass air flow determination and reducing fuel consumption by optimizing air-fuel ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass air flow measurement is used to control exhaust-gas recirculation, then EGR rate can be determined, but measurement stability deteriorates due to sensor durability problems and fluctuations
Solution Approach 1:
The patent introduces an intermediary calculation method that uses turbocharger speed and exhaust-gas lambda values as mediators to determine EGR rate indirectly, avoiding direct reliance on the unreliable mass air flow sensor. This intermediary approach maintains measurement precision while eliminating the reliability issues of the original sensor.
Solution Approach 2:
The patent replaces the mechanical/electrical mass air flow sensing system with a computational approach based on turbocharger speed and lambda measurements. This substitution eliminates the problematic sensor while achieving the same control function through alternative physical measurements and mathematical relationships.
2Object-generated harmful factors
If oxygen sensors are upgraded for accurate NOx emission control, then emission control improves, but system cost increases significantly
Solution Approach 1:
The patent creates a virtual model or calculation-based copy of the oxygen sensing function using existing sensors (turbocharger speed and lambda). Instead of installing expensive additional oxygen sensors, the system replicates the emission control information through computational methods, achieving the same control accuracy without the additional hardware cost.
Solution Approach 2:
The patent changes the measurement parameters from direct oxygen concentration measurement (requiring expensive sensors) to alternative parameters (turbocharger speed and lambda) that can be measured more economically. By measuring different parameters and deriving the required information through calculation, the system achieves emission control without expensive sensor upgrades.
3Object-generated harmful factors
If more EGR is recirculated to reduce NOx emissions, then emission reduction improves, but air-fuel ratio becomes progressively richer increasing fuel consumption
Solution Approach 1:
The patent implements a feedback control system that continuously monitors exhaust-gas lambda and turbocharger speed to determine actual EGR rate and its effect on air-fuel ratio. This feedback allows the system to adjust EGR recirculation to achieve the minimum necessary for emission control, preventing excessive EGR that would enrich the air-fuel ratio and increase fuel consumption.
Solution Approach 2:
The patent introduces dynamic adjustment of EGR rate based on real-time measurements of turbocharger speed and exhaust-gas lambda. Instead of fixed or overly aggressive EGR recirculation, the system dynamically optimizes the EGR rate to maintain proper air-fuel ratio while achieving emission reduction, adapting to changing engine operating conditions to minimize fuel consumption.
Data Source
AI summary
The present disclosure provides systems and methods for adjusting an exhaust gas recirculation rate to provide accurate air-fuel ratio. The disclosure provides a method for calculating an exhaust-gas recirculation rate based on a measured exhaust-gas lambda and a turbocharger speed. Through the use of the exhaust-gas lambda and the turbocharger speed it is possible to calculate an exhaust-gas recirculation rate while dispensing with the difficult and unreliable determination of the mass air flow for determining an exhaust-gas recirculation rate, thus providing a stable method which further reduces fuel consumption and emissions.