EGR Flow Rate Determination Using Venturi Pressure Sensing
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Solution Overview
Problem
Existing methods for determining the mass flow rate of exhaust gas recirculation in internal combustion engines are costly or require excessive computing power, and may be affected by contaminants, limiting their accuracy and reliability.
Innovation Solution
A method involving a venturi to sense differential and absolute exhaust pressures, along with temperature, to calculate the mass flow rate of exhaust gases, which is then used to regulate the flow through a recirculation valve arrangement, minimizing space and reducing the impact of contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mass flow rate sensor is used to determine exhaust flow rate, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical mass flow rate sensor with a computational model that calculates exhaust mass flow rate using the ideal gas law and measured parameters (pressure differential across EGR valve, absolute pressure, temperature, and EGR valve position). This substitution eliminates the need for complex mechanical sensors while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces an intermediary computational approach that uses readily available sensor data (pressure, temperature, valve position) combined with gas law calculations to derive exhaust mass flow rate. This intermediary method avoids direct mechanical measurement complexity while achieving the same measurement objective.
2Device complexity
If a compact throttle body arrangement with integrated microcomputer is used, then device complexity is reduced, but computing power requirements increase
Solution Approach 1:
The patent changes the computational parameters from requiring complex real-time mass flow calculations to using a simplified model based on the ideal gas law with easily measurable parameters (pressure differential, absolute pressure, temperature, and valve position). This reduces the computing power burden while maintaining integration in the compact throttle body.
3Productivity
If existing mass flow determination methods are used, then flow rate regulation is achieved, but reliability is reduced due to contaminant sensitivity
Solution Approach 1:
The patent replaces mechanical mass flow sensors that are susceptible to contaminant damage with a computational method using pressure, temperature, and position sensors. These alternative sensors are more reliable in contaminated exhaust environments, maintaining EGR regulation capability while improving system reliability.
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 provides a cost-effective, accurate, and reliable method for regulating exhaust gas recirculation, enhancing engine performance and compliance with emission standards while reducing NOx formation and particulate matter.
Implementation Method 1
directing the exhaust gases through a venturi and sensing a differential exhaust pressure across the venturi
Data Source
AI summary
A method of determining and regulating a mass flow rate exhaust gases recirculated into an engine is disclosed. The method may comprise directing the exhaust gases through a venturi and sensing a differential exhaust pressure across the venturi. The method may further include sensing an absolute exhaust pressure at the venturi, and sensing a temperature of the exhaust gases. The method may further include determining the mass flow rate of the exhaust based on the sensed differential fluid pressure, absolute fluid pressure, and temperature.