Lambda Sensor Diagnosis via Superimposed Current Pulses
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Solution Overview
Problem
Existing methods for diagnosing lambda sensors during operation often result in temporary signal invalidity, which can lead to violations of emissions monitoring regulations, especially when performed in parallel with pump current operation, and typically require coasting or start-stop phases of the engine, which are undesirable.
Innovation Solution
A method that involves adding a pump current pulse and a counter pulse to the pump current to diagnose lambda sensors, allowing for malfunction detection with minimal interruption to the pump current operation, using voltage measurements from the pump cell and Nernst cell, and adjusting the counter pulse amplitude to neutralize Nernst voltage changes and diffusion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If diagnostic measurements are performed during ongoing pump current operation, then diagnostic capability is improved, but signal invalidity and regulation stability deteriorate
Solution Approach 1:
The patent applies periodic action by implementing diagnostic measurements as time-limited pulses superimposed on the continuous pump current operation. The diagnostic current pulses are applied periodically at specific measurement points during ongoing operation, allowing diagnostics without complete operation interruption. This resolves the contradiction by enabling automated diagnostics while maintaining continuous pump current function through periodic measurement superposition.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing characteristic values (such as diffusion characteristics and flow characteristics) that are used during diagnostic evaluations. These preliminary computations enable rapid diagnostic decisions during ongoing operation without requiring time-consuming real-time calculations that would interrupt pump current operation. This allows diagnostic capability enhancement while maintaining signal validity through pre-prepared evaluation criteria.
2Measurement precision
If diagnostic measurements interrupt pump current operation, then measurement accuracy is improved, but operational continuity and emissions compliance deteriorate
Solution Approach 1:
The patent applies merging by combining the diagnostic current pulses with the ongoing pump current operation. Instead of separating diagnostics from operation, the diagnostic measurements are merged into the pump current timeline as superimposed pulses. This allows diagnostic measurement accuracy to be maintained through proper pulse design while operational continuity is preserved because the pump current never fully stops, only experiences brief measurement superposition.
Solution Approach 2:
The patent applies partial action by implementing brief diagnostic current pulses that provide sufficient measurement accuracy for diagnostic purposes without fully interrupting the pump current operation. The pulses are designed to be long enough to obtain accurate measurements but short enough to maintain operational continuity. This partial interruption approach resolves the contradiction between measurement precision and productivity.
3Speed
If pump current pulses are added during operation, then diagnostic speed is improved, but system stability and emissions monitoring compliance worsen
Solution Approach 1:
The patent applies feedback by continuously monitoring the lambda sensor signals during and after diagnostic pulse application. The control system uses feedback from the sensor responses to detect malfunctions and adjust subsequent diagnostic pulse parameters. This feedback mechanism allows rapid diagnostic speed through immediate pulse application while maintaining system stability by using the sensor responses to guide further diagnostic actions and ensure emissions compliance.
Solution Approach 2:
The patent applies dynamics by making the diagnostic pulse parameters (amplitude, duration, timing) adaptive rather than fixed. The system dynamically adjusts pulse characteristics based on operating conditions and sensor responses. This dynamic approach enables fast diagnostic speed through optimized pulse application while maintaining control system stability by adapting to changing conditions and preventing excessive disturbances to the pump current operation.
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 diagnostic measurements with minimal disruption to the pump current operation, allowing for the detection of malfunctions such as mechanical damage or capacitor impairment, and ensures the control system returns to a stable state quickly, preventing emissions violations.
Implementation Method 1
a malfunction as a result of an impairment of the capacitors on the pump cell and the Nernst cell of the lambda sensor may be ascertained, which results in a misinterpretation of the pump current within the meaning of the Nernst principle
Implementation Method 2
changes of the Nernst voltage of the lambda sensor are neutralized by the pump current pulse, the pump current counter pulse, and diffusion effects and flow effects occurring between these pulses
Data Source
AI summary
A method for diagnosing a lambda sensor during ongoing operation. It includes energizing the lambda sensor using a pump current pulse additive to a pump current and a pump current counter pulse additive to the pump current and ascertaining a malfunction of the lambda sensor from voltages, which are measured at a pump cell and/or a Nernst cell of the lambda sensor during the energization by the pulses.