Tracking Exhaust Gas Constituents in Turbocharged LPEGR Systems
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Solution Overview
Problem
Turbocharged gasoline engines with low pressure exhaust gas recirculation (LPEGR) systems face challenges in accurate control and estimation of exhaust gas constituents due to long flow paths and high costs associated with multiple sensors, leading to potential misfires and reduced fuel economy.
Innovation Solution
A control system that utilizes a differential pressure valve and a limited set of sensors to maintain differential pressure across the EGR valve, track exhaust gas constituents through the LPEGR system, and adjust airflow and fuel injection to prevent misfires, incorporating a controller that determines air/fuel ratios at various points in the system and adjusts the wastegate, throttle, and spark plug operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to accurately track exhaust gas constituents through the LPEGR system, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential measurement function from multiple potential sensors, using a single exhaust gas concentration sensor positioned upstream from the EGR pickup. The controller then performs computational extraction of exhaust gas constituent data at multiple locations along the flow path by modeling mass balances, eliminating the need for physical sensors at each point while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical approach of placing physical sensors throughout the LPEGR system with an information processing approach. The controller uses mathematical models and computational algorithms to substitute for multiple physical measurement devices, calculating exhaust gas constituent concentrations at various points through mass balance equations rather than direct physical measurement.
2Measurement precision
If multiple sensors are installed throughout the LPEGR system to track exhaust gas constituents, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the expensive component of multiple sensors from the system, retaining only one essential sensor. The controller performs computational extraction of data at multiple locations using mass balance calculations, significantly reducing manufacturing cost while preserving the ability to track exhaust gas constituents throughout the LPEGR system.
Solution Approach 2:
The patent substitutes expensive physical sensor infrastructure with a computational system. The controller uses mathematical modeling and processing algorithms to replace multiple physical measurement devices, reducing system cost while maintaining precise tracking of exhaust gas constituents through the entire recirculation path.
3Temperature
If the LPEGR system uses a long flow path to cool and recirculate exhaust gas, then exhaust gas cooling is improved, but the difficulty of tracking exhaust gas constituents increases
Solution Approach 1:
The patent replaces direct physical measurement of exhaust gas constituents at multiple locations along the long flow path with a computational modeling approach. The controller uses mass balance equations and processed data from a single upstream sensor to calculate constituent concentrations at various points throughout the extended recirculation path, making tracking feasible despite the long flow path.
Solution Approach 2:
The patent introduces the controller as an intermediary between the single exhaust gas concentration sensor and the multiple measurement points along the flow path. The controller acts as a computational mediator that processes sensor data and applies mass balance calculations to determine exhaust gas constituent concentrations at various locations without requiring direct physical access to each point.
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
The system achieves precise control of exhaust gas constituents, reducing the risk of misfires and improving fuel economy by accurately tracking and managing exhaust gas fractions and fuel fractions throughout the engine cycle, while minimizing the need for expensive sensors.
Implementation Method 1
an exhaust gas concentration sensor upstream from an EGR pickup of the LPEGR system and configured to measure an air/fuel ratio of the exhaust gas
Implementation Method 2
an EGR cooler and an EGR valve downstream from the EGR cooler
Implementation Method 3
the control system comprises... a controller configured to... maintain differential pressure across the EGR valve
Data Source
AI summary
Systems and methods for a turbocharged gasoline engine utilize an exhaust gas concentration sensor disposed upstream from an exhaust gas recirculation pickup point of a low pressure EGR (LPEGR) system of the engine and a controller configured to receive a measured air/fuel ratio of the exhaust gas from the sensor, determine an air/fuel ratio of the exhaust gas at the EGR pickup point, determine an air/fuel ratio of the exhaust gas at an inlet and outlet of an EGR cooler, determine first/second sets of exhaust gas fractions and fuel fractions upstream/downstream from an EGR port that is upstream from a compressor in an induction system of the engine, and control at least one of a wastegate valve, a throttle valve, a fuel injector, and a spark plug based on the sets of second exhaust gas fractions and fuel fractions to prevent misfires of the engine.