Variable Geometry Turbine Transient Control for Compression Ignition Engines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The concurrent use of turbo-charging and exhaust gas recirculation in compression ignition engines complicates control over engine performance, particularly during transient events, leading to inefficient operation and increased NOx emissions due to the interplay between mass airflow, pumping losses, and fuel efficiency.
Innovation Solution
A method is implemented to dynamically adjust the position of the variable geometry turbine to maximize mass air flow and minimize pumping losses by detecting engine transients, determining current mass air flow and exhaust temperature, and adjusting exhaust pressure to optimize turbine operation, while also controlling the EGR valve to manage emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a VGT is used to control mass airflow in the intake manifold, then torque response and fuel economy are improved, but pumping losses increase during transient events
Solution Approach 1:
The patent applies dynamics by making the turbine geometry variable through movable guide vanes that can adjust their angle dynamically. This allows the turbine to adapt its flow characteristics in real-time during transient events, optimizing the balance between torque response and pumping losses by changing the effective flow area and pressure ratio across the turbine.
Solution Approach 2:
The patent changes physical parameters including the turbine inlet guide vane angle, exhaust manifold pressure, and mass airflow rate to optimize performance during transient conditions. By dynamically adjusting these parameters, the system achieves improved torque response while minimizing pumping losses through coordinated control of the VGT and EGR valve.
2Object-generated harmful factors
If EGR valve is used to control emissions, then NOx emissions are reduced, but mass airflow control becomes complicated
Solution Approach 1:
The patent merges the control functions of the VGT and EGR valve into a coordinated control strategy. By combining the mass airflow control capability of the VGT with the emissions control capability of the EGR valve, the system achieves both reduced NOx emissions and simplified control logic through integrated management of both components.
Solution Approach 2:
The patent implements feedback control by continuously monitoring engine operating conditions including mass airflow, exhaust temperature, and pressure, then using this information to dynamically adjust both the VGT and EGR valve positions. This feedback mechanism simplifies control complexity by automatically optimizing the interaction between the two components based on real-time engine state.
3Productivity
If mass airflow is increased to improve fuel combustion, then fuel efficiency increases, but pumping losses increase
Solution Approach 1:
The patent uses dynamic adjustment of the VGT geometry to optimize the balance between mass airflow and pumping losses. During transient events, the guide vanes adjust to maintain appropriate pressure ratios and flow characteristics that maximize fuel combustion efficiency while minimizing the energy lost to pumping operations.
Solution Approach 2:
The patent employs periodic control adjustments during transient engine operation, where the VGT and EGR valve are continuously adjusted in response to changing operating conditions. This periodic action allows the system to optimize the trade-off between mass airflow for fuel combustion and pumping losses throughout the transient event.
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 enhances engine efficiency and torque output during transient conditions while minimizing NOx emissions and pumping losses, ensuring optimal fuel combustion and reduced engine pumping work.
Implementation Method 1
Exhaust turbines have long been used to recover energy from high pressure exhaust gas produced by most internal combustion engines. One use of the recovered energy is to drive a compressor/supercharger
Implementation Method 2
drive a compressor/supercharger on the intake side of the engine and thereby increase the mass of the air charge delivered to engine combustion chambers
Implementation Method 3
Exhaust gas displaces fresh air in the combustion cylinders and functions as an inert gas in the cylinder reducing cylinder temperature during combustion and thus reducing the formation of nitrous oxides
Implementation Method 4
Variable geometry turbines (VGT) are used with turbo-charged engines to reduce engine pumping losses
Data Source
AI summary
A method of setting actuator position of a variable geometry turbine linked to drive a compressor for a compression ignition engine using exhaust gas recirculation. The method includes detecting an engine transient event; determining current mass air flow through the compressor and exhaust temperature; resetting variable geometry turbine position to maximize mass air flow through the compressor; adding the maximum allowable quantity of fuel; determining exhaust temperature increase; adjusting exhaust pressure to allow an increase in mass air flow and exhaust temperature; and returning to the resetting step until a limit is reached.