Exhaust Catalyst Oxygen Charging Control via Sensor Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Internal combustion engines face challenges in achieving low pollutant emissions due to the limitations of existing exhaust gas treatment systems, particularly in managing the oxygen charging of catalytic converters during overrun phases, which can lead to increased NOX emissions and unnecessary pollutant release.
Innovation Solution
A method and device that monitor the oxygen charging of a second catalytic exhaust converter using a second exhaust gas sensor, determining a characteristic variable for oxygen charging as a function of engine operating variables, and controlling an enrichment phase to precisely manage oxygen storage and prevent pollutant emissions, without requiring additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the air-fuel mixture is enriched during overrun phase to charge the first catalytic exhaust converter with oxygen, then the oxygen storage capacity of the first converter is improved, but the NOX emissions increase due to excessive oxygen charging
Solution Approach 1:
The control device monitors the measuring signal of the second exhaust gas sensor to detect the signal characteristic indicating maximum oxygen charging of the first converter, and uses this feedback to terminate the enrichment phase at the optimal moment, preventing excessive oxygen storage and NOX formation
Solution Approach 2:
The system performs preliminary charging of the first catalytic converter with oxygen during the overrun phase, but precisely controls the duration by monitoring the second sensor's signal characteristic, ensuring the converter is charged to maximum capacity without overcharging that would lead to NOX emissions
2Ease of operation
If the oxygen charging of catalytic converters is not precisely controlled, then the enrichment phase can be simplified, but pollutant emissions increase due to improper oxygen storage management
Solution Approach 1:
The system uses feedback from the second exhaust gas sensor to precisely control the enrichment phase duration, enabling accurate oxygen storage management that reduces pollutant emissions while maintaining manageable operational complexity through automated control
Solution Approach 2:
The system replaces complex mechanical timing mechanisms with an electronic control system that uses sensor signals to automatically determine when to terminate the enrichment phase, achieving precise oxygen charging control without complicated mechanical timing devices
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 enables precise control of oxygen charging in catalytic converters, reducing pollutant emissions and preventing unnecessary hydrocarbon release, while ensuring accurate determination of oxygen storage capacity and minimizing NOX emissions.
Implementation Method 1
a second exhaust gas sensor, which is disposed downstream of the first catalytic exhaust converter and upstream of the second catalytic exhaust converter, the measuring signal of which is monitored for a signal characteristic that is characteristic of attainment of a maximum possible degree of charging of the first catalytic exhaust converter with oxygen
Implementation Method 2
catalytic exhaust converters are used, which convert carbon monoxide, hydrocarbons and nitrous oxides into harmless substances
Implementation Method 3
a signal characteristic that is characteristic of attainment of a maximum possible degree of charging of the first catalytic exhaust converter with oxygen
Data Source
AI summary
An internal combustion engine has an exhaust gas tract with a first and a second exhaust gas catalyst downstream of the first one, a first exhaust gas sensor, which is disposed upstream or in the first catalyst, and a second exhaust gas sensor, which is disposed downstream of the first catalyst and upstream of the second catalyst. During trailing throttle operation, the measurement signal of the second sensor is monitored for a signal characteristic that is typical of a maximum possible saturation state with oxygen that the first catalyst can achieve, upon which a characteristic variable is determined for a saturation state of the second catalyst with oxygen as a function of an engine operating variable. Outside the trailing throttle operation, an enrichment mode is controlled by enriching the air/fuel mixture, specifically as a function of the characteristic variable for the saturation state of the second catalyst with oxygen.