Dual-loop EGR Control for Turbocharger Pressure Stability
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Solution Overview
Problem
In engines with variable geometry turbochargers and dual-loop EGR systems, the feedback control of intake manifold pressure and EGR control often interfere, leading to unintended results due to unbalanced high-pressure and low-pressure EGR quantities, which can cause inappropriate vane openings and poor exhaust performance.
Innovation Solution
A controlling apparatus that switches between single and combination uses of EGR systems, prohibiting feedback control of intake manifold pressure during a predetermined period and executing feedforward control to maintain balance between EGR quantities, using a pressure controller to adjust vanes and recirculation controllers to manage EGR flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control of intake manifold pressure is executed simultaneously with EGR control, then both controls can operate independently, but the controls interfere with each other causing unintended results and inappropriate vane openings
Solution Approach 1:
The patent applies preliminary action by detecting the switching timing of EGR systems in advance and temporarily suspending feedback control of intake manifold pressure during the switching period. This prevents the feedback control from generating inappropriate vane openings that would occur due to transient imbalances in EGR quantities, thereby eliminating control interference while maintaining control stability.
2Productivity
If EGR control adjusts total EGR quantity rapidly, then exhaust gas recirculation efficiency improves, but intake air temperature becomes unbalanced causing poor exhaust performance
Solution Approach 1:
The patent applies feedback by continuously monitoring the temperatures of intake air from high-pressure and low-pressure EGR systems and using this information to regulate EGR quantities. When temperature imbalance is detected, the control adjusts the EGR distribution to maintain proper thermal balance, ensuring both high EGR efficiency and optimal exhaust performance through temperature-managed recirculation.
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
Prevents interference between EGR and intake manifold pressure controls, rapidly achieving target pressures and maintaining proper EGR balance, resulting in improved exhaust performance by adjusting intake air temperature.
Implementation Method 1
a variable geometry turbocharger including a turbine (32) disposed in an exhaust path, a compressor (31) disposed in an intake path
Implementation Method 2
variable geometry turbochargers have been widespread that include flow-rate adjusting mechanisms called variable vanes in the vicinity of the turbines of the turbochargers
Implementation Method 3
turbines that are rotated by the energy of exhaust gas and that drive compressors provided coaxially thereto to supercharge compressed air to cylinders
Data Source
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AI summary
A first recirculation system (40) includes a first adjuster (45,14) to adjust the exhaust-gas flow rate in a first path (41) connecting an upstream position of a turbine (32) of a VG turbocharger (30) to a downstream position of a compressor (31). A second recirculation system (50) includes a second adjuster (55,13) to adjust the exhaust-gas flow rate in a second path (51) connecting a downstream position of the turbine (32) to an upstream position of the compressor (31). A recirculation controller (63) switches between a single use activating the first or second recirculation system (40,50) and a combination use activating both systems (40,50) by controlling the adjusters (45,14,55,13). A pressure controller (64) executes feedback control of an intake-system pressure through adjusting the opening of vanes (33), and executes feedforward control without the feedback control during a predetermined period from the switching from the single use to the combination use.