Engine Emission Control via Sensor Drift Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems controlling internal combustion engine fuel mixtures using oxygen sensors are prone to drift due to aging and environmental factors, leading to momentary extreme signals that cause instability in catalyst operation and emission levels.
Innovation Solution
A method involving two oxygen sensors, where instantaneous signals are processed to calculate average values and deviations, and a PID algorithm is used to adjust the fuel mixture setpoint based on these calculations, ensuring stable emission control by conditioning sensor signals and reacting to deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a downstream oxygen sensor is used to correct sensor drift, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the downstream oxygen sensor continuously monitors exhaust gas oxygen levels and provides corrective signals to the fuel control system. This feedback loop detects and compensates for upstream sensor drift by adjusting the fuel mixture based on actual catalyst outlet conditions, thereby maintaining measurement precision without requiring complex manual calibration procedures.
Solution Approach 2:
The downstream oxygen sensor acts as an intermediary that indirectly corrects upstream sensor errors. Instead of directly replacing the upstream sensor, the system uses the downstream sensor's measurements of exhaust gas composition to infer upstream sensor drift and apply corrective adjustments, simplifying the overall system architecture while maintaining accuracy.
2Measurement precision
If extreme corrective actions are taken to compensate for sensor drift, then measurement precision is improved, but stability of the object's composition deteriorates
Solution Approach 1:
The patent employs dynamic signal processing that adapts the corrective actions based on real-time conditions. The system continuously adjusts the fuel mixture setpoint based on the magnitude and duration of sensor drift detections, applying larger corrections when drift is significant and smaller corrections when conditions are stable. This dynamic approach prevents extreme abrupt changes while maintaining precision.
Solution Approach 2:
The system implements periodic monitoring and correction cycles, where the fuel control system repeatedly measures exhaust gas composition and applies incremental corrections. This periodic action smooths out extreme corrections by distributing them over multiple measurement cycles, thereby maintaining catalyst operation stability while achieving precise fuel mixture control.
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 method effectively maintains consistent tailpipe emissions over time without manual calibration, stabilizing the fuel mixture and reducing sudden changes in catalyst operation.
Implementation Method 1
a catalytic converter in communication with the first sensor and adapted to receive exhaust gases from the exhaust manifold and to oxidize carbon monoxide and hydrocarbon pollutants
Data Source
AI summary
A method for controlling internal combustion engine emissions, including the steps of reading signals from sensors in an engine exhaust manifold and catalytic converter exhaust, an upstream one of the sensors being provided with an air-fuel mixture setpoint, comparing signal values with previous average values and automatically adjusting the air-fuel mixture set point to vary the fuel mixture fed to the engine.