Dual Element Oxygen Sensor for EGR Control
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Solution Overview
Problem
Existing oxygen sensors in engine intake systems are confounded by sensitivities to diluents like fuel vapor and humidity, leading to reduced accuracy in exhaust gas recirculation (EGR) measurement and control.
Innovation Solution
A dual element oxygen sensor system comprising a catalyzing sensor and a non-catalyzing sensor is used to measure intake oxygen concentration and fuel vapor concentration, allowing for separate determination of EGR and fuel vapor levels, thereby adjusting EGR and fuel injection parameters for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a catalyzing sensor is used to measure oxygen concentration, then the sensor can detect oxidants and reductants, but the sensor becomes sensitive to fuel vapor and other reductants which confounds the measurement
Solution Approach 1:
The invention divides the measurement function into two separate sensors: a catalyzing sensor that detects both oxygen and fuel vapor, and a non-catalyzing sensor that detects only oxygen. By segmenting the sensing functions, the system can differentiate between oxygen concentration and fuel vapor interference, resolving the measurement accuracy problem while maintaining adaptability to various gas constituents.
Solution Approach 2:
The control system acts as an intermediary that processes signals from both catalyzing and non-catalyzing sensors. It calculates the difference between the two sensor outputs to determine fuel vapor concentration, while using the non-catalyzing sensor output for accurate oxygen-based EGR measurement. This intermediary processing separates the confounded measurements into distinct components.
2Measurement precision
If the sensor equilibrates the sensed gas to detect oxygen, then the sensor can measure oxygen concentration, but the equilibration process makes the sensor sensitive to fuel vapor which reduces measurement accuracy
Solution Approach 1:
The system segments the sensing approach by deploying two parallel sensing paths: one with catalyzing elements that equilibrate and detect both oxygen and fuel vapor, and another without catalyzing elements that equilibrates and detects only oxygen. This segmentation allows the system to isolate and compensate for fuel vapor interference while maintaining accurate oxygen detection capability.
Solution Approach 2:
The control system uses feedback from both sensors to continuously monitor and differentiate between oxygen concentration and fuel vapor presence. By comparing the outputs of catalyzing and non-catalyzing sensors, the system can feedback-correct measurements to eliminate fuel vapor interference while preserving oxygen detection accuracy.
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 the accuracy of EGR measurement and control by reducing equilibration effects at the sensing surface, enabling precise adjustments to fuel injection and vapor purge based on fuel vapor concentration.
Implementation Method 1
Due to equilibration of the sensed gas by a catalyzing sensing element of the sensor, the oxygen sensor is sensitive to both the partial pressure of oxygen and the presence of fuel (or other reductants and oxidants)
Implementation Method 2
By using a non-catalyzing sensor, equilibration at a sensing surface of the sensor is reduced such that fuel vapor acts as a diluent instead of directly reducing the measured oxidant level
Data Source
AI summary
Various systems and methods are described for an engine system with an exhaust gas recirculation system and catalyzing and non-catalyzing intake oxygen sensors. In one example, the catalyzing oxygen sensor is utilized to measure and control exhaust gas recirculation while fuel vapor purge is measured and controlled based on the catalyzing and non-catalyzing sensors.