Wideband Lambda Sensor Line Diagnosis Using Switched Voltage Drops
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Solution Overview
Problem
Existing systems fail to reliably determine whether the electrical connections between a wideband lambda sensor and a control unit are intact or interrupted.
Innovation Solution
A control unit with specific electrical inputs and switches, along with a measuring resistor and current sources, is used to diagnose the integrity of electrical lines by measuring voltage drops across the resistor under different switching configurations, employing threshold comparisons and pre-evaluations to distinguish between intact and interrupted lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a measuring resistor is used to detect line interruptions by measuring voltage drops, then diagnostic capability is improved, but measurement precision deteriorates because the voltage drop is too small to reliably distinguish from zero voltage indicating an interrupted line
Solution Approach 1:
The patent applies preliminary action by first closing the intermediate switch SwtAPE to connect the current source to the measuring resistor before performing the voltage measurement. This preparatory step ensures that sufficient current flows through the measuring resistor to generate a measurable voltage drop, thereby enabling reliable line interruption detection without compromising the lambda sensor operation
Solution Approach 2:
The patent uses an intermediate switch SwtAPE as a mediator between the current source and the measuring resistor. This switch enables controlled connection of the current source to the measuring resistor only when diagnostic measurement is required, allowing the system to achieve sufficient measurement signal while maintaining normal operational conditions and preventing interference with lambda sensor function
2Measurement precision
If the current source is continuously connected to generate sufficient voltage for reliable measurement, then measurement precision is improved, but interference to the lambda sensor operation increases
Solution Approach 1:
The patent implements periodic action by using switches SwtAPE and SwtMES to connect the current source to the measuring resistor only during specific diagnostic measurement periods. The intermediate switch SwtAPE is closed temporarily to enable current flow for measurement, then opened to restore normal lambda sensor operation, thereby achieving reliable voltage measurement without continuous interference
Solution Approach 2:
The patent applies preliminary action by first closing the intermediate switch SwtAPE to connect the current source to the measuring resistor before performing the voltage measurement. This preparatory step ensures that sufficient current flows through the measuring resistor to generate a measurable voltage drop, thereby enabling reliable line interruption detection without compromising the lambda sensor 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 reliable detection of line interruptions with minimal interference to the lambda sensor's operation, improving diagnostic accuracy and reducing technical effort in distinguishing small voltage differences from zero.
Implementation Method 1
measuring the voltage Uam dropping across the measuring resistor
Data Source
AI summary
A control unit and a method for diagnosing lines between a wideband lambda sensor and the control. By means of specific circuitry and evaluation, it is determined, for each individual line, whether or not there is an interruption or failure of the line in question. A method for more accurately measuring the value of a calibration resistor of the wideband lambda sensor is also described.