Virtual NOx Sensor Using Combustion Pressure

Solution Overview

Problem

Conventional methods for predicting NOx generation in vehicle engines require additional sensors and devices for exhaust gas analysis, leading to increased costs and potential contamination, with complex calculations and simplified assumptions compromising reliability.

Innovation Solution

A method that calculates NO generation rate using combustion pressure and driving variables like fuel amount, engine speed, and air/fuel ratio, predicting NOx generation without additional sensors by determining burned gas temperature and oxygen/nitrogen concentrations in the combustion chamber, and using empirical ratios to estimate NO2 generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors or devices for exhaust gas analysis are used to predict NOx amount, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

ImproveNOx amount prediction precisionVSAvoidsensor and device complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

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 existing engine parameters (combustion pressure, temperature, air-fuel ratio, EGR rate). This virtual sensor approach eliminates the need for additional physical sensors while maintaining prediction capability.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/physical sensor-based detection system with an information-processing system that uses mathematical calculations and computational models. Instead of physically measuring NOx concentrations, the system processes engine operating data through standardized equations to derive NOx generation amounts.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If additional sensors or devices for exhaust gas analysis are used to predict NOx amount, then measurement precision is improved, but cost increases

Engineering Contradiction:

ImproveNOx amount prediction precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

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 existing engine parameters (combustion pressure, temperature, air-fuel ratio, EGR rate). This virtual sensor approach eliminates the need for additional physical sensors while maintaining prediction capability.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/physical sensor-based detection system with an information-processing system that uses mathematical calculations and computational models. Instead of physically measuring NOx concentrations, the system processes engine operating data through standardized equations to derive NOx generation amounts.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If simplified assumptions are used to reduce calculation complexity, then device complexity is reduced, but reliability deteriorates

Engineering Contradiction:

Improvecalculation process complexityVSAvoidprediction reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent uses standardized empirical equations with fixed parameters (A, B, C, D constants) that balance calculation simplicity with prediction accuracy. These parameters are derived from extensive experimental data and represent optimized relationships between engine parameters and NOx generation, achieving reliable predictions without overly complex calculations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent incorporates multiple feedback loops where calculated NOx generation amounts are compared with actual measurements (when available), and the differences are used to refine the prediction model. This continuous validation and adjustment process ensures reliability while maintaining calculation efficiency.

Inventive Principle:

Principle #23Feedback

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

Enables precise, real-time prediction of NOx generation with reduced costs and improved reliability by eliminating the need for additional sensors, thus acting as a virtual sensor for NOx detection.

Implementation Method 1

combustion of an air/fuel mixture

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

adiabatic flame temperature (Tad) and a temperature rise of the burned gas in the combustion chamber due to pressure rise at combustion

Methodology Applied

Scientific EffectAdiabatic heating: Adiabatic Heating

Implementation Method 3

catalytic converters are used for converting carbon monoxide, hydrocarbon, and nitrogen oxide into harmless material

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS8849544B2Method of predicting NOx generation amount

Publication Date: 2014.09.30 HYUNDAI MOTOR CO LTD

AI summary

A method of predicting NOx generation amount may include calculating NO generation rate by using a combustion pressure of an engine and driving variables of the engine, obtaining NO generation period by using the combustion pressure of the engine, calculating NO generation amount based on the NO generation rate and the NO generation period, and predicting the NOx generation amount by obtaining NO2 generation amount based on a ratio between NO and NO2 according to the NO generation amount and a driving condition of the engine.