Wide Range Active Compressor for HP-EGR Pressure Differential
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Solution Overview
Problem
Highly efficient turbochargers lead to reduced turbine power, diminishing the pressure differential necessary for effective exhaust gas recirculation (EGR) flow, which adversely affects engine performance and increases fuel consumption when attempts are made to reinforce the pressure differential through throttling or pumps.
Innovation Solution
Implementing a wide range active compressor (WRAC) with an active casing treatment or variable inlet device to modulate compressor efficiency, adjusting the surge slot and choke slot, or varying the compressor inlet diameter to control the pressure differential between the exhaust and intake systems, thereby enhancing EGR flow without throttling the engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a highly efficient turbocharger is used, then boosting efficiency is improved, but the pressure differential for EGR flow deteriorates
Solution Approach 1:
The patent applies dynamics by making the compressor casing treatment adjustable rather than fixed. The active casing treatment allows the compressor to switch between different efficiency modes: high efficiency mode for normal operation and reduced efficiency mode when EGR flow is needed. This dynamic adjustment resolves the contradiction by allowing the system to have high turbocharger efficiency when needed while temporarily reducing it to create sufficient pressure differential for EGR flow.
Solution Approach 2:
The patent changes the operational parameters of the compressor by modifying the casing treatment configuration. By adjusting the active casing treatment (such as variable stator vanes or adjustable diffuser vanes), the compressor's pressure-ratio and efficiency characteristics are changed. This allows the system to maintain high turbocharger efficiency during normal operation while being able to reduce compressor efficiency temporarily to increase exhaust pressure and maintain the pressure differential required for effective EGR flow.
2Productivity
If the VGT vanes are adjusted to a more closed position to maintain air/fuel ratios, then boosting is improved, but the pressure upstream of the turbine increases which diminishes the pressure differential for EGR flow
Solution Approach 1:
The patent applies dynamics by making the compressor casing treatment adjustable rather than fixed. The active casing treatment allows the compressor to switch between different efficiency modes: high efficiency mode for normal operation and reduced efficiency mode when EGR flow is needed. This dynamic adjustment resolves the contradiction by allowing the system to have high turbocharger efficiency when needed while temporarily reducing it to create sufficient pressure differential for EGR flow.
Solution Approach 2:
The active casing treatment acts as an intermediary mechanism between the turbocharger and EGR system. Instead of directly adjusting VGT vane position (which affects both boosting and EGR pressure differential), the active casing treatment provides an indirect control method. By modifying compressor characteristics, it influences exhaust gas pressure and flow distribution, thereby maintaining the pressure differential for EGR while allowing the VGT to focus on air/fuel ratio control.
3Stress or pressure
If engine throttling is used to increase vacuum at the intake manifold, then the negative pressure differential for EGR flow is improved, but fuel economy deteriorates
Solution Approach 1:
The patent applies self-service by using the turbocharger's own compressor, equipped with active casing treatment, to generate the necessary pressure differential for EGR flow. Instead of relying on engine throttling (which sacrifices fuel economy) or external pumps, the system uses its existing turbocharger infrastructure. By dynamically adjusting the compressor casing treatment, the turbocharger itself creates the conditions needed for effective EGR flow without requiring additional energy-consuming components or sacrificing fuel efficiency.
Solution Approach 2:
The patent changes the operational parameters of the compressor by modifying the casing treatment configuration. By adjusting the active casing treatment (such as variable stator vanes or adjustable diffuser vanes), the compressor's pressure-ratio and efficiency characteristics are changed. This allows the system to maintain high turbocharger efficiency during normal operation while being able to reduce compressor efficiency temporarily to increase exhaust pressure and maintain the pressure differential required for effective EGR flow.
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
Maintains EGR flow and reduces NOx emissions while improving fuel economy by adjusting compressor efficiency to increase the pressure differential, ensuring effective engine dilution and performance.
Implementation Method 1
increasing the pressure differential between an exhaust system upstream of a turbine and an intake system downstream of a compressor
Implementation Method 2
The rotation of the turbine is often powered by rapidly expanding exhaust gas generated at the combustion chambers
Implementation Method 3
Turbochargers forcibly induct extra air into combustion chambers of the engine
Data Source
AI summary
Methods and systems are provided for an engine system configured with a wide range active compressor and high pressure EGR. In one example, a compressor may include an active casing treatment with a slideable sleeve may be adjusted to direct air flow through either a choke slot and surge slot to control compressor efficiency, thereby maintaining EGR flow. In another example, the compressor may comprise a variable inlet device to regulate air flow through the compressor, thereby adjusting compressor efficiency and also maintaining EGR flow.