Exhaust Gas Sensor Diagnosis Using Reference Channel Oxygen Storage
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Solution Overview
Problem
Existing methods for diagnosing the measuring ability of exhaust gas sensors in internal combustion engines, particularly for rich air-fuel ratios, are inefficient and lead to increased emissions and fuel consumption, as they require actual rich gas mixtures, which are not feasible for diesel engines operated in lean modes.
Innovation Solution
A method involving a 'breathing mode' where a high voltage fills the reference gas channel with oxygen, allowing for the evaluation of the sensor's measuring ability through electrochemical reactions and subsequent current pulses, mimicking rich gas conditions without altering engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rich gas mixture is supplied to the exhaust gas sensor for diagnosis, then the rich measuring ability can be tested, but emissions increase and fuel consumption increases
Solution Approach 1:
A reference gas channel filled with oxygen serves as an intermediary medium to simulate rich exhaust gas conditions. Instead of introducing actual rich exhaust gas, the patent uses a controlled oxygen environment in the reference channel to create the necessary electrochemical conditions for diagnosing rich measuring ability, thereby avoiding increased emissions while maintaining diagnostic reliability
Solution Approach 2:
The patent creates a simulated copy of rich exhaust gas conditions by controlling the oxygen concentration in the reference gas channel. By adjusting the oxygen level in this reference channel, the system replicates the electrochemical behavior that would occur with actual rich exhaust gas, allowing diagnosis without producing harmful emissions
2Reliability
If a rich gas mixture is supplied to the exhaust gas sensor for diagnosis, then the rich measuring ability can be tested, but fuel consumption increases
Solution Approach 1:
The reference gas channel acts as an intermediary that decouples the diagnosis process from actual engine operation. By using a controlled oxygen environment in this reference channel, the system can test rich measuring ability without requiring the engine to operate in fuel-consuming rich mode
Solution Approach 2:
The system uses its own internal reference gas channel and oxygen storage capabilities to generate the test conditions needed for diagnosis. The exhaust gas sensor's reference channel, which already contains oxygen, is utilized to create simulated rich conditions, eliminating the need for external rich gas supply and associated fuel consumption
3Measurement precision
If the pump current is used to determine the lambda value, then the lambda value can be measured, but the transport processes differ greatly between lean and rich exhaust gas
Solution Approach 1:
The patent creates different local conditions in the reference gas channel to match the specific diagnostic needs. By controlling the oxygen concentration locally in the reference channel, the system can simulate rich conditions (high oxygen concentration) without affecting the overall lean operation of the engine, allowing accurate rich measuring ability diagnosis while maintaining lean operating conditions
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 reliable diagnosis of the rich measuring ability without switching to rich exhaust gas operation, reducing emissions and fuel consumption, and improving diagnostic accuracy by utilizing oxygen transport and electrochemical reactions to simulate rich gas conditions.
Implementation Method 1
Single-cell limiting current sensors may have the particular feature of containing a large reference gas channel for oxygen storage
Implementation Method 2
the cell including at least one first electrode, at least one second electrode and at least one solid electrolyte connecting the first electrode and the second electrode
Implementation Method 3
The pump current of the lambda sensor is used to determine the lambda value. The pump current is positive in the case of a lean exhaust gas and is negative in the case of a rich exhaust gas
Data Source
AI summary
A method and device for diagnosing a measuring ability of an exhaust gas sensor in an exhaust gas channel of an internal combustion engine. A sensor design including a storage volume in a reference gas channel, at least one first electrode facing an electrode cavity connected to the exhaust gas channel, and a second electrode facing the reference gas channel is used as the exhaust gas sensor. Such a high voltage is applied between the first electrode and the second electrode during a first phase that the reference gas channel is filled with additional oxygen as a result of decomposition of water and/or carbon dioxide, and a pump current from the first electrode to the second electrode is used to evaluate the measuring ability during a second phase.