Wideband Lambda Sensor Short-Circuit Diagnosis With Protected Switching
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Solution Overview
Problem
Existing evaluation and control units for broadband lambda sensors are vulnerable to high electrical loads during faults, such as short circuits, which can cause damage and hinder diagnostic processes.
Innovation Solution
The implementation of voltage-proof switches with low resistance and the use of voltage dividers to safely connect electrical connections to ground, allowing for targeted diagnosis by measuring short-circuit voltages within the measuring range of the system, and determining short-circuit resistances and voltages to identify fault lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches are used to connect electrical connections to ground for protection, then damage protection is improved, but the switches are exposed to high electrical loads and may fail under fault conditions
Solution Approach 1:
The patent introduces voltage dividers as intermediary components between the switches and the electrical connections. These voltage dividers reduce the voltage exposure of switches during fault conditions by dividing the voltage, allowing switches to operate within safe voltage limits while still providing protection functionality.
Solution Approach 2:
The patent implements protection mechanisms that are activated beforehand or designed to limit exposure before damage occurs. The voltage dividers are pre-configured to limit the maximum voltage exposure of switches to a predetermined safe value, cushioning them against high electrical loads before damage can occur.
2Reliability
If voltage dividers are used to reduce voltage exposure, then switch protection is improved, but device complexity increases
Solution Approach 1:
The patent makes the voltage dividers serve multiple functions: they protect switches from overvoltage, enable diagnostic measurements of line faults, and work with the existing switch protection mechanism. This multi-functionality reduces the need for separate protection circuits, thereby limiting the increase in device complexity.
3Measurement precision
If switches are designed as low-resistance switches for diagnostic purposes, then measurement precision is improved, but through-resistance must be carefully controlled
Solution Approach 1:
The patent specifies that switches should have low resistance (not greater than 100 ohms or the internal resistance of the electrochemical cells) to enable accurate fault diagnosis. This parameter specification ensures that the switches do not significantly affect measurements during diagnostic operations while still providing effective protection when closed.
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
This solution protects the evaluation and control unit from damage during faults, enables effective diagnostic processes, and accurately identifies short-circuit locations and voltages, ensuring reliable operation and maintenance of broadband lambda sensors.
Implementation Method 1
In particular, a voltage divider is provided between the respective switch and the defined electrical potential. In the event of a fault, this divider allows a partial voltage of the maximum expected short-circuit voltage to be tapped
Implementation Method 2
each electrical connection is assigned an electrical switch via which the respective connection can be connected to ground
Implementation Method 3
In the event of a fault, this divider allows a partial voltage of the maximum expected short-circuit voltage to be tapped, provided it lies within the measuring range of a measuring system, such as an ADC
Data Source
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AI summary
The invention relates to an evaluation and control unit for operating a wideband lambda sensor (200), which has at least two electrical lines (201, 202, 203, 204). The evaluation and control unit (100) has at least two electrical terminals (RE, IPE, APE, MES) for electrically connecting to the electrical lines (201, 202, 203, 204) of the wideband lambda sensor (200). An electrical switch (SwtRE, SwtIPE, SwtAPE, SwtMES) is associated with each of the electrical terminals (RE, IPE, APE, MES), by means of which electrical switch the terminal (RE, IPE, APE, MES) in question can be individually connected to at least one defined electrical potential (GND, VSET1, VSET2). Each switch (SwtRE, SwtIPE, SwtAPE, SwtMES) is able to withstand the maximum short-circuit voltage (Usc) expected at the terminal (RE, IPE, APE, MES) in question in the event of a fault. The invention further relates to a method for the line-specific short-circuit diagnosis of the wideband lambda sensor (pinpointing).