Engine EGR System Shortening Recirculation Path
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Solution Overview
Problem
Conventional exhaust gas recirculation systems have a long recirculation path, leading to time delays in controlling the EGR ratio, which increases errors and deteriorates control performance, especially in transitional periods.
Innovation Solution
The engine system minimizes the exhaust gas recirculation path by incorporating an electric supercharger, a cylinder deactivation device, and an EGR valve mounted closer to the intake line, reducing the distance between the EGR valve and the combustion chamber, and branching the recirculation line from the downstream portion of the exhaust gas processing device to the upstream portion of the electric compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the recirculation line is branched from the rear end of the catalyst and joined to the front end of the compressor (conventional LP-EGR configuration), then the exhaust gas can be recirculated, but the recirculation path becomes very long causing time delay in controlling EGR ratio
Solution Approach 1:
The patent extracts the EGR valve from its conventional position at the compressor inlet and relocates it to the exhaust manifold. This extraction of the valve from its original position and placement at a different location shortens the recirculation path by allowing exhaust gas to be diverted earlier in the exhaust flow path, reducing the distance gas must travel and improving control responsiveness.
Solution Approach 2:
Instead of the conventional approach where the recirculation line branches from the exhaust downstream (after catalyst) and joins the intake upstream (before compressor), the patent inverts the configuration by branching the recirculation line from the exhaust manifold (upstream) and joining it to the intake line after the intercooler (downstream). This reversal of the recirculation path direction and timing reduces the path length and control delay.
2Ease of operation
If the EGR valve is positioned farther from the combustion chamber (conventional configuration), then the system layout is simpler, but the control performance in transitional periods deteriorates due to increased time delay
Solution Approach 1:
The patent extracts the EGR valve from the intake path near the compressor and relocates it to the exhaust manifold. This repositioning places the control valve closer to the source of exhaust gas, enabling faster response to control signals and improving transient control performance without requiring complex controller algorithms to compensate for delays.
3Measurement precision
If a long recirculation path is used (conventional configuration), then the EGR system can be implemented with standard components, but the error of EGR ratio increases due to time delay
Solution Approach 1:
The patent extracts the recirculation line from the conventional long path configuration (catalyst rear end to compressor front end) and reconfigures it to branch from the exhaust manifold and join after the intercooler. This extraction and repositioning of the recirculation line significantly shortens the path length, reducing the time for exhaust gas to circulate and improving the accuracy of EGR ratio measurement and control.
Solution Approach 2:
The patent inverts the conventional recirculation path configuration by reversing the branching and joining points. Instead of branching from downstream exhaust and joining to upstream intake, the system branches from upstream exhaust (exhaust manifold) and joins to downstream intake (after intercooler), creating a shorter and more efficient recirculation path that improves measurement precision.
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 configuration allows for precise control of the EGR ratio in transitional periods, improving control responsiveness and reducing errors, while also simplifying the engine layout and potentially reducing manufacturing costs by omitting the wastegate valve.
Implementation Method 1
an EGR cooler mounted on the recirculation line to cool the recirculation gas
Implementation Method 2
an electric compressor operated by the motor to supply the supercharged air to the combustion chamber
Implementation Method 3
supplied to a combustion chamber of the engine via an intercooler
Data Source
AI summary
An engine system may include an engine having an intake line flowing an intake gas supplied to the combustion chambers; an intake manifold; a throttle valve provided at a front of the intake manifold and controlling an air amount supplied to the combustion chamber; an electric supercharger provided at the throttle valve and including a motor and an electric compressor operated by the motor to supply the supercharged air to the combustion chamber; an exhaust gas processing device purifying an exhaust gas generated in the combustion chamber; and an exhaust gas recirculation device including a recirculation line branched from the downstream portion of the exhaust gas processing device and joined to the intake line of the upstream portion of the electric compressor, an EGR cooler mounted at the recirculation line, and an EGR valve mounted at a part where the recirculation line and the intake line are joined.