Lambda Probe Diagnosis via Dynamic Lean-Rich Transitions
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Solution Overview
Problem
Existing methods for diagnosing the functional reliability of a lambda probe in catalytic converters are not reliable under all conditions, leading to potential misdiagnosis of oxygen storage capacity and catalytic converter functionality.
Innovation Solution
The method involves initiating the change from lean to rich exhaust gas and vice versa based on specific signal thresholds and time derivatives recorded by the lambda probe, allowing for direct feedback and optimal regulation, and includes waiting for operator-induced changes, such as coasting, to ensure accurate diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the change from lean to rich exhaust gas is periodically induced using fixed timing intervals, then the diagnosis method works reliably under most control device settings, but it fails to work reliably under all possible conditions including unusual conditions
Solution Approach 1:
The patent transitions from fixed periodic timing intervals to dynamic event-based triggering. The diagnosis is initiated by detecting specific events (lambda probe signal threshold crossings) rather than following a predetermined schedule. This allows the system to adapt to varying operating conditions and engine control strategies, ensuring reliable diagnosis across all possible conditions including unusual ones.
Solution Approach 2:
The patent implements feedback by using the lambda probe's own signals to trigger the diagnosis process. When the lambda probe signal crosses a threshold value, this event automatically initiates the diagnosis sequence. This feedback mechanism ensures the diagnosis is performed at the optimal moment and adapts to real-time engine operating conditions, improving both reliability and adaptability.
2Measurement precision
If the diagnosis waits for a time interval after the change is detected, then signals can be recorded for analysis, but the diagnosis response time is delayed
Solution Approach 1:
The patent performs preliminary actions by continuously monitoring and recording lambda probe signals before the diagnosis is actually needed. When a threshold crossing event occurs, the pre-recorded signals are immediately available for analysis without requiring additional waiting time. This eliminates the delay between detection and diagnosis while maintaining measurement precision.
Solution Approach 2:
The patent skips the traditional waiting period by using event-triggered diagnosis. Instead of waiting for a predetermined time interval to expire before analyzing signals, the system immediately initiates diagnosis when the lambda probe signal crosses the threshold value, rushing through the process while maintaining accuracy through selective signal analysis.
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 reliability of lambda probe diagnosis by using signals during controlled changes in oxygen charging, ensuring accurate assessment of probe functionality under various conditions.
Implementation Method 1
a lambda probe 6 which is located downstream of the exhaust gas catalytic converter 3... based on the signals of the lambda probe
Data Source
AI summary
In the change from lean to rich exhaust gas or vice versa, signals are recorded by a lambda probe and are used to diagnose the functional reliability of this lambda probe. So that special reliability of this procedure is ensured, the change is triggered by an event. The event can be defined by signals of the lambda probe or can be caused by control actions of the operator in the motor vehicle.