Nernst Cell Sensor Timing Correction for Lambda Signal Jitter
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Solution Overview
Problem
Conventional sensors for detecting gas properties, such as lambda probes, suffer from jitter in the pump current signal, leading to unreliable cylinder-specific enrichment detection due to latency and variable components, which can cause uneven distribution of lambda values among engine cylinders, reducing component lifespan and necessitating complex diagnostic strategies.
Innovation Solution
A method that includes measuring Nernst voltage, recording timestamps, and correcting timestamps with a predetermined time delay to eliminate jitter, allowing for reliable cylinder-specific enrichment detection by processing sensor data with a ring buffer to ensure accurate timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sensors are used for detecting gas properties, then the sensor can detect oxygen concentration and lambda values, but jitter in the pump current signal leads to unreliable cylinder-specific enrichment detection
Solution Approach 1:
The patent applies preliminary action by assigning timestamps to pump current values at the moment of measurement and storing them in a buffer memory before processing. This allows the system to capture the exact timing of each measurement, enabling subsequent correction of timing deviations and elimination of jitter effects in the signal evaluation.
Solution Approach 2:
The patent implements feedback by comparing the assigned timestamps with the actual processing times and calculating timing deviations. This feedback mechanism allows the system to identify and correct jitter effects by determining when measurements were actually taken versus when they are processed, thereby improving the reliability of cylinder-specific enrichment detection.
2Stability of the object's composition
If pump current signal is evaluated without timestamp correction, then processing is simpler, but latency and variable components cause uneven distribution of lambda values among engine cylinders
Solution Approach 1:
The patent applies preliminary action by pre-assigning timestamps to each pump current value at the moment of measurement and storing them in a buffer memory. This preliminary timing documentation enables subsequent correction of timing deviations without requiring complex real-time processing, thereby stabilizing lambda values across cylinders while maintaining manageable processing complexity.
Solution Approach 2:
The patent introduces an intermediary buffer memory that stores pump current values with their associated timestamps before final processing. This intermediary structure decouples the measurement timing from the processing timing, allowing the system to correct for timing variations and achieve uniform lambda distribution without directly complicating the core measurement process.
3Measurement precision
If timestamp correction with predetermined time delay is implemented, then jitter is eliminated and detection precision improves, but processing time and computational requirements increase
Solution Approach 1:
The patent applies preliminary action by assigning timestamps to all pump current values at the moment of measurement and storing them in advance in a buffer memory. This preliminary timing documentation eliminates the need for complex real-time timing calculations, allowing jitter correction to be performed efficiently with minimal additional processing time while maintaining high measurement precision.
4Reliability
If complex diagnostic strategies are used to address uneven lambda distribution, then cylinder-specific issues can be identified, but system complexity and component lifespan requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-capturing exact measurement timestamps and storing pump current values with their timing information in a buffer memory. This preliminary organization of data with precise timing information simplifies subsequent diagnostic analysis, enabling accurate cylinder-specific enrichment detection without requiring complex diagnostic strategies, thereby reducing overall system complexity while maintaining high diagnostic accuracy.
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
The method effectively removes jitter from the sensor signal, enabling precise and reliable detection of gas properties, thereby improving the longevity and performance of engine components by ensuring consistent lambda values across cylinders.
Implementation Method 1
the ratio of the oxygen partial pressure in the cavity to the oxygen partial pressure in a further reference gas chamber can be determined via the forming Nernst voltage
Implementation Method 2
an oxygen ion current diffuses through a ceramic body (the oxygen-conducting solid electrolyte), which separates the gases from one another
Implementation Method 3
an oxygen ion current diffuses through a ceramic body
Data Source
AI summary
A method for operating a sensor for detecting at least one property of a measured gas in a measurement gas chamber. The method includes: measuring a Nernst voltage of the Nernst cell, and, based on the Nernst voltage, quantitatively determining a target variable describing the property of the measured gas; recording a target variable data packet based on the target variable; assigning a current timestamp to the target variable data packet; processing the target variable data packet on a signal processing path; requesting a current system time; correcting the timestamp of the currently processed target variable data packet based on a predetermined time delay and the current system time; converting the corrected timestamp to form a number of measured values; ascertaining a time correction index for the target variable based on the number of measured values; and ascertaining a corrected target variable value based on the time correction index.