Low Pressure EGR Valve Control for Diesel Engine Emissions
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Solution Overview
Problem
The existing high-pressure EGR systems in diesel engines face challenges in achieving precise control and effective emission reduction, particularly in meeting stricter emission regulations like Euro 5 and Euro 6, due to high EGR gas temperatures and longer gas paths, which deteriorate controllability in low-pressure systems.
Innovation Solution
A method and apparatus for controlling a low-pressure EGR valve in a turbocharged diesel engine, utilizing sensors to detect engine speed, load, intake air, and EGR gas conditions, with a controller executing a program to determine and adjust the EGR valve's control duty based on estimated temperatures, pressures, and mass flow rates, enhancing responsiveness and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a low pressure EGR system is used to reduce emission, then emission reduction capability is improved, but controllability deteriorates due to longer gas path and lower pressure
Solution Approach 1:
The patent implements a feedback control system that continuously monitors EGR rate and adjusts the EGR valve duty cycle accordingly. The controller receives feedback signals from sensors measuring exhaust gas flow and intake air conditions, then dynamically adjusts the low pressure EGR valve opening to maintain precise control despite the longer gas path and lower pressure conditions.
Solution Approach 2:
The patent changes the operating parameters of the EGR system by transitioning from high pressure to low pressure operation, specifically by taking exhaust gas after the turbocharger and DPF rather than before. This parameter change enables better emission reduction while the control system compensates for the resulting lower pressure and longer path through active adjustment of valve timing and opening duration.
2Ease of operation
If high pressure EGR system is used, then controllability is maintained, but emission reduction capability is insufficient for stricter regulations
Solution Approach 1:
The patent segments the EGR system into distinct pressure zones by implementing both high pressure EGR (before turbocharger) and low pressure EGR (after turbocharger and DPF) pathways. This segmentation allows the system to leverage the controllability advantages of high pressure operation while also achieving the emission reduction benefits of low pressure operation with cooler, cleaner exhaust gas.
Solution Approach 2:
The patent introduces the turbocharger and DPF as intermediary components in the exhaust gas path. By positioning the low pressure EGR valve downstream of these intermediaries, the system benefits from the pressure recovery and filtration provided by the turbocharger and DPF, enabling precise control and reduced emissions simultaneously.
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 prompt realization of a desired EGR rate, improving the controllability and emission reduction capabilities of low-pressure EGR systems, enabling compliance with stricter emission regulations.
Implementation Method 1
an intercooler downstream-side temperature detector for detecting an intake air temperature at a downstream side of the intercooler
Implementation Method 2
an EGR cooler upstream-side temperature detector for detecting an EGR gas temperature at an upstream side of an EGR cooler
Data Source
AI summary
A low pressure EGR valve is controlled by mixing EGR gas into an intake air. Steps of the method include detecting temperature and pressure of an intake air passing through an air cleaner, detecting temperature and pressure of the intake air at a downstream side of an intercooler, detecting temperature and pressure of an EGR gas at an upstream side of an EGR cooler, determining a control duty of the low pressure EGR valve on the basis of the detected temperature and pressure of the air passing through the air cleaner, the detected temperature and pressure at the downstream side of the intercooler, and the detected temperature and pressure at the upstream side of the EGR cooler, and controlling the low pressure EGR valve based on the determined control duty. An apparatus for executing the method is also provided.