Particle Sensor Self-Diagnosis via Ion Migration Correction
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Solution Overview
Problem
Existing resistive particle sensors for detecting soot particles in exhaust gases face accuracy issues during self-diagnosis due to sodium ion mobility and heater coupling, leading to incorrect diagnosis results.
Innovation Solution
A method involving multiple current-voltage measurements with specific electrode potential configurations and correction value calculations to compensate for heater coupling, ensuring accurate self-diagnosis by measuring and correcting for ion migration effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-diagnosis is performed during sensor regeneration with elevated temperature and applied electrical potential, then the diagnostic function can be executed, but heater coupling causes sodium ion migration that distorts the measurement and leads to incorrect diagnostic results
Solution Approach 1:
The patent applies preliminary action by performing a first current-voltage measurement before the second measurement during which the measuring electrode is at different electrical potential. This preliminary measurement establishes a baseline that accounts for heater coupling effects, allowing the system to later compensate for ion migration distortion in the actual diagnostic measurement.
Solution Approach 2:
The patent implements feedback by using the results from the first current-voltage measurement to compensate for heater coupling in the second measurement. The system continuously monitors the ion migration effects and adjusts the diagnostic interpretation based on this feedback, improving the accuracy of defect detection despite the presence of sodium ion mobility during regeneration.
2Measurement precision
If multiple current-voltage measurements are performed with different electrode potentials to compensate for heater coupling, then measurement precision is improved, but device complexity and measurement time increase
Solution Approach 1:
The patent applies universality by using the same measuring electrodes and control unit for both the preliminary current-voltage measurement and the diagnostic measurement. The existing sensor hardware performs multiple functions: it conducts both baseline measurements for heater coupling compensation and actual diagnostic measurements, avoiding the need for additional specialized components.
Solution Approach 2:
The patent implements parameter changes by varying the electrical potential of the measuring electrode between the first and second measurements. By changing this electrical parameter, the system can distinguish between current caused by heater coupling and current caused by actual electrode defects, enabling accurate diagnosis without adding physical complexity.
3Object-generated harmful factors
If the positive measuring electrode is grounded during regeneration phases, then heater coupling effects are reduced, but the diagnostic function cannot be performed during these phases
Solution Approach 1:
The patent applies periodic action by performing the diagnostic measurement during specific phases of the regeneration cycle when the electrical potential conditions are appropriate. Rather than continuously grounding the electrode or continuously performing diagnostics, the system alternates between measurement phases and regeneration phases, optimizing both heater coupling reduction and diagnostic availability.
Solution Approach 2:
The patent uses preliminary action by performing the first current-voltage measurement when the electrode is grounded to establish baseline data about heater coupling effects. This preliminary data collected during grounding phases is then used to compensate for distortions in subsequent diagnostic measurements, allowing the system to benefit from both grounded and ungrounded phases.
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 enhances the accuracy of self-diagnosis by isolating the current generated by the measuring pulse and correcting for ion migration, providing reliable defect detection without hardware changes, thus improving diagnostic reliability.
Implementation Method 1
it is cleaned in specific phases using an integrated heating element. The sensor signal is evaluated within the system by comparing the target trigger time, determined from a signal behavior model that incorporates the raw emission model, with the actual sensor trigger time.
Implementation Method 2
since regeneration typically lasts for many seconds to minutes, positively charged particles, especially sodium ions, experience a driving force for this extended period, moving from the interior of the sensor, where the heater is located, to the surface where the measuring electrode is situated. Due to the high sensor temperature during this phase, the sodium ions exhibit high mobility and migrate upwards.
Implementation Method 3
a measuring voltage is applied to the electrodes at the end of the regeneration process. This generates an ion current, which is usually caused by impurities in the form of sodium. If this current exceeds a certain threshold, the electrodes are considered intact.
Data Source
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AI summary
A method for controlling the function of a sensor (10) for detecting particles, in particular soot, is proposed, wherein the sensor (10) has at least two measuring electrodes (20, 22) and a substrate (18) on which the measuring electrodes (20, 22) are arranged. The method comprises the following steps: carrying out a first current/voltage measurement in order to determine a first measurement variable, carrying out a second current/voltage measurement in order to determine a second measurement variable, wherein one measuring electrode (22) of the measuring electrodes (20, 22) is connected to a different electrical potential (50), carrying out a third current/voltage measurement in order to determine a third measurement variable, and forming a correction value for correcting the second measurement variable by means of the first measurement variable and the third measurement variable.