Wideband Lambda Probe Line Interruption Detection With Dual-Current Testing
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Solution Overview
Problem
Existing methods struggle to reliably detect and differentiate between interruptions in electrical lines connected to a broadband lambda sensor, particularly when the voltage drops are small and difficult to distinguish from zero.
Innovation Solution
A control unit with specific electrical inputs and switches, along with a current source and measuring resistor, is used to diagnose line interruptions by comparing voltage drops across the resistor against predetermined threshold values, and additional measurements are employed to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage drop measurement is used to detect line interruptions, then line interruption detection is enabled, but small voltage drops are difficult to distinguish from zero voltage
Solution Approach 1:
The patent applies periodic action by using two different current strengths (first current and second current) to perform sequential measurements. The first measurement uses a first current strength to detect large voltage drops indicating line interruptions, while the second measurement uses a second current strength to detect small voltage drops. This periodic switching between different measurement conditions enables reliable distinction between small voltage drops and zero voltage drops.
Solution Approach 2:
The patent changes the current strength parameter between two distinct values (first current strength and second current strength) to perform different types of measurements. By varying this electrical parameter, the system can adaptively detect both large and small voltage drops with appropriate sensitivity, resolving the measurement precision issue for small voltage drops.
2Measurement precision
If multiple measurements with different current strengths are performed, then measurement accuracy is improved, but measurement time and system complexity increase
Solution Approach 1:
The patent segments the measurement process into two distinct stages: a first measurement stage using a first current strength for detecting line interruptions, and a second measurement stage using a second current strength for verifying small voltage drops. This segmentation allows the system to perform specialized measurements in sequence, improving accuracy while keeping each individual measurement quick and efficient.
Solution Approach 2:
The patent applies partial action by performing the first measurement with a first current strength that is sufficient for detecting line interruptions, and only performing the second measurement with a second current strength when needed (when the first measurement indicates a possible small voltage drop). This conditional approach avoids unnecessary measurements, reducing overall measurement time while maintaining high 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
Accurately identifies line interruptions with high precision, minimizing interference with the lambda sensor's operation and enabling simultaneous oxygen concentration measurement.
Implementation Method 1
a measuring means for measuring the voltage U am dropping across the measuring resistor
Implementation Method 2
an electrochemical pump cell which is connected between the first electrical connection IPE and the second electrical connection APE
Implementation Method 3
an electrochemical reference cell connected between the first electrical terminal and the fourth electrical terminal
Data Source
Figure 1
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AI summary
The invention relates to a control unit (2) and to a method for diagnosing lines (203, 204) between a wideband lambda sensor (1) known per se and the control unit (2). By means of specific circuitry and evaluation, it is determined, for each individual line, whether there is an interruption or failure of the line (203, 204) in question. The invention also relates to a method for more accurately measuring the value of a calibration resistor (212) of the wideband lambda sensor (1).