Catalytic Converter Diagnosis via Cold Wave Axial Positioning
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Solution Overview
Problem
Existing methods for diagnosing the storage capacity and conversion performance of catalytic converters in internal combustion engines do not provide a differentiated assessment of damage location and region, which affects conversion performance differently depending on the axial position within the converter.
Innovation Solution
A method involving a brief supply of cooler exhaust gas to create a cold wave within the catalytic converter, allowing computation of the axial position and determination of the storage unit's size through an exhaust gas probe signal, enabling a differentiated assessment of serviceability and damage by examining the effects of the cold wave on pollutant conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional diagnosis methods are used to assess catalytic converter performance, then overall conversion performance can be monitored, but differentiated assessment of damage location and region is not achieved
Solution Approach 1:
The catalytic converter is divided into multiple axial regions (entry region, exit region, intermediate regions) for differentiated assessment. The cold wave method segments the converter into zones based on temperature distribution, allowing independent evaluation of each region's storage capacity and conversion performance rather than treating the converter as a single unit.
Solution Approach 2:
The diagnosis method changes the temperature parameter of the exhaust gas by introducing cooler exhaust gas to create a cold wave. This parameter change enables the detection of regional differences in storage capacity by observing how different sections of the catalytic converter respond to the temperature transient, providing location-specific diagnostic information.
2Loss of information
If the catalytic converter is continuously monitored at operating temperature, then conversion performance can be assessed, but regional damage identification is not possible
Solution Approach 1:
A cold wave is deliberately introduced into the catalytic converter before normal operation to pre-condition the system for diagnosis. This preliminary action creates a temporary temperature gradient that highlights regional differences in storage capacity, allowing information to be gathered during a brief diagnostic window without requiring continuous monitoring interruptions.
Solution Approach 2:
The cold wave diagnosis is performed periodically during coasting phases or low-load operations when the engine is already decelerating. This periodic action integrates the diagnosis into existing operational cycles, minimizing additional time loss while capturing regional serviceability information that would otherwise be lost during continuous operation.
3Measurement precision
If cooler exhaust gas is supplied to create a cold wave, then regional storage capacity can be determined, but conversion performance may temporarily decrease
Solution Approach 1:
Cooler exhaust gas is supplied in a controlled, partial manner rather than completely replacing hot exhaust gas. The cold wave is introduced as a transient condition during brief diagnostic windows (coasting phases), providing sufficient temperature contrast for accurate measurement while limiting the duration and extent of temperature reduction to minimize impact on overall conversion performance.
Solution Approach 2:
The diagnosis utilizes existing coasting phases of engine operation when exhaust gas flow and temperature conditions are already favorable for cold wave propagation. The system leverages natural operational variations rather than requiring active intervention, performing diagnosis during periods when the engine is already in a state conducive to the measurement without additional energy input or performance sacrifice.
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 allows for a reliable diagnosis of storage unit serviceability and damage location, ensuring adequate pollutant conversion by determining the size of the storage unit relative to given boundary values, differentiating the impact of damage in entry and exit regions on pollutant conversion.
Implementation Method 1
the catalytic converter is briefly supplied with cooler exhaust gas so that a cold wave which passes through the catalytic converter forms
Implementation Method 2
the temperature of the catalytic converter at the position of the cold wave is just below the starting temperature
Data Source
AI summary
In a method for diagnosing a storage-capable catalytic converter of an internal combustion engine which is supplied with sufficiently hot exhaust gas so that its temperature is above the starting temperature of the exhaust gas, it is proposed that the catalytic converter is briefly supplied with cooler exhaust gas so that a cold wave passing through it forms, that the axial position of the cold wave within the catalytic converter is computed, and that the size of the storage unit is determined from the signal of an exhaust gas probe connected downstream from the catalytic converter relative to the axial position of the cold wave. According to the invention, a differentiated diagnosis method is made available by which not only the axial position or the region of damage of the storage unit can be determined, but by which the reduction of conversion of a certain pollutant A,B caused by the axial position of the damage can be indicated.