Virtual NOx Sensor Using Combustion Pressure
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Solution Overview
Problem
Conventional methods for predicting and controlling NOx emissions in internal combustion engines rely on additional sensors and devices, which increase costs and are prone to contamination and reliability issues due to complex calculations and simplified assumptions, leading to inaccurate NOx amount prediction and unreliable control.
Innovation Solution
A system and method that uses combustion pressure and driving variables to predict NOx generation without additional sensors, employing a virtual sensor to calculate NO generation rate, period, and amount, and adjusting fuel injection, EGR rate, and boost pressure to control NOx emissions based on a predetermined target, thereby eliminating the need for physical NOx sensors and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors or devices for analyzing exhaust gas are used to detect NOx amount, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual sensor that copies the function of physical NOx sensors by calculating NOx generation amount through mathematical models using combustion pressure and driving variables. This virtual sensor replicates sensor functionality without requiring physical NOx detection devices, thereby improving measurement precision while avoiding the complexity and contamination issues of actual sensors.
Solution Approach 2:
The patent replaces the mechanical/physical sensor-based detection system with a computational model that uses combustion pressure data and driving variables to calculate NOx generation. This substitution eliminates the need for physical NOx sensors, reducing device complexity while maintaining measurement capability through mathematical modeling.
2Measurement precision
If physical sensors for detecting NOx are installed, then measurement precision is improved, but reliability deteriorates due to contamination and sensor failure
Solution Approach 1:
The virtual sensor copies the detection function without physical contact with exhaust gases, eliminating contamination risks. By using combustion pressure and driving variables in calculations, the system achieves reliable NOx measurement without the sensor failure issues inherent in physical sensors exposed to harsh exhaust environments.
Solution Approach 2:
The patent introduces combustion pressure and driving variables as intermediary parameters to indirectly determine NOx generation amount. Instead of directly measuring NOx with sensors that are prone to contamination, the system uses these intermediary variables that are easier to measure and less susceptible to exhaust gas contamination, thereby improving reliability.
3Device complexity
If simplified assumptions are used to reduce calculation complexity, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent changes the parameters used in calculations from simplified assumptions to actual measured combustion pressure and driving variables. This parameter change allows the system to maintain relatively simple calculation processes while significantly improving NOx generation amount prediction accuracy, as the calculations use real engine operating conditions rather than theoretical assumptions.
Data Source
AI summary
A system and a method for controlling NOx may include predicting NOx generation amount by using a virtual sensor; comparing the NOx prediction amount with a predetermined NOx target amount; and controlling the NOx generation amount so as for the NOx prediction amount to follow the NOx target amount.