Wideband Lambda Sensor Short-Circuit Pinpointing Circuit
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Solution Overview
Problem
Conventional switches in wideband lambda sensor evaluation and control units are exposed to high electrical loads during faults, such as short circuits, which can cause damage and hinder diagnostic processes, especially in miniaturized ASIC implementations.
Innovation Solution
Incorporating voltage-resistant switches with low-ohmic characteristics and voltage dividers to safely handle maximum short-circuit voltages, allowing for diagnostic capabilities by subdividing voltages within the measurement range of the evaluation and control unit, and using a method to pinpoint short-circuit locations by measuring currents through individual terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switches are used in the evaluation and control unit, then the device complexity is reduced and ease of manufacture is improved, but the switches are exposed to high electrical loads during faults which causes damage and reduces reliability
Solution Approach 1:
The patent implements protective measures before faults occur by designing switches with voltage resistance against maximum short-circuit voltages and providing voltage dividers that automatically limit voltages to safe levels. This beforehand cushioning ensures the evaluation and control unit is protected when faults happen, without requiring complex protective mechanisms to be added later.
2Reliability
If voltage-resistant switches with constructive measures are implemented, then reliability is improved, but the device complexity increases due to additional insulation and shielding
Solution Approach 1:
The patent introduces voltage dividers as intermediary components between the switches and the maximum short-circuit voltages. These voltage dividers act as mediators that automatically limit the voltages to safe levels during faults, protecting the switches without requiring complex insulation and shielding measures, thus maintaining ease of manufacture while improving reliability.
3Measurement precision
If voltage dividers are added for diagnostic purposes, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent designs the voltage dividers to serve multiple functions: they protect the switches from voltage damage during faults and simultaneously enable diagnostic measurements by providing safe voltage levels for the measurement system. This multi-functionality allows the same components to improve both reliability and measurement precision without proportionally increasing device complexity.
4Measurement precision
If low-ohmic switches are used for accurate diagnosis, then measurement precision is improved, but the switches are more susceptible to damage from high currents during faults
Solution Approach 1:
The patent uses voltage dividers as intermediary protective elements that limit the voltages and currents flowing through the low-ohmic switches during faults. This allows the switches to maintain their low-ohmic characteristics for accurate diagnostic measurements while being protected from damaging currents by the voltage-dividing action during fault conditions.
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
Ensures the protection of the evaluation and control unit from damage during faults, enables effective diagnosis of electrical lines, and accurately determines short-circuit locations, thereby facilitating appropriate technical measures.
Implementation Method 1
a voltage divider is provided between the respective switch and the defined electrical potential, by which, in case of fault, a partial voltage of the maximum short-circuit voltage to be expected can be picked off that is within the measurement range of a measurement system
Implementation Method 2
the respective switch be realized as a low-ohmic switch, i.e., having in the closed state in particular a volume resistance that is not greater than the internal resistance of the electrochemical cells of the wideband lambda sensor at operating temperature
Data Source
AI summary
An evaluation and control unit for operating a wideband lambda sensor that has at least two electrical lines, the evaluation and control unit having at least two electrical terminals for electrical connection to the electrical lines of the wideband lambda sensor. Each of the electrical terminals has assigned to it a respective electrical switch via which each terminal is capable of being individually connected to at least one defined electrical potential. Each switch is voltage-resistant against the maximum short-circuit voltage that is to be expected at the respective terminal in case of fault. In addition, a method is described for the line-specific short-circuit diagnosis of the wideband lambda sensor (pinpointing).