Broadband Lambda Probe Cable Fault Diagnosis
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Solution Overview
Problem
Existing methods for monitoring cable faults in broadband lambda probes, particularly in internal combustion engine exhaust gas ducts, are limited in their ability to detect faults outside specific diagnosis modes like switch-on or warm-up, and struggle to unambiguously identify cable breaks in the terminals.
Innovation Solution
A method utilizing a controlled pump current and pulsed reference pump current, managed by a control unit with switching matrices, to create defined states at the probe terminals, allowing for unambiguous cable diagnosis through evaluation of potential swings and voltage drops, even outside designated diagnosis modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional diagnosis modes (switch-on or warm-up) are used for monitoring cable faults, then the monitoring can be performed during these specific modes, but the ability to identify faults outside these modes is limited
Solution Approach 1:
The pump cell is made multi-functional by enabling it to serve both its primary function (oxygen pumping during normal operation) and a diagnostic function (fault detection through controlled pump current). The control unit implements multiple operating modes including a diagnosis mode that uses the pump cell for fault detection, thereby making the single component serve multiple purposes and resolving the contradiction between reliability and adaptability
2Measurement precision
If a controlled pump current with predetermined direction is applied through the pump cell, then cable breaks can be unambiguously diagnosed, but the monitoring becomes restricted to specific diagnosis modes
Solution Approach 1:
The system performs preliminary diagnostic actions by applying controlled pump current with predetermined direction before normal operation or during dedicated diagnosis periods. This preliminary action charges the terminals in specific ways that enable unambiguous cable break diagnosis, while the control unit manages the timing to maintain operational flexibility
3Measurement precision
If potential swings are evaluated to identify cable faults, then unambiguous diagnosis is achieved, but the method requires additional controlled current application that limits continuous monitoring
Solution Approach 1:
The diagnostic process using controlled pump current and potential swing evaluation is implemented periodically during designated diagnosis modes rather than continuously. The control unit schedules these diagnostic intervals appropriately, allowing unambiguous fault identification when performed while maintaining system operational availability between diagnostic periods
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 the unambiguous identification and assignment of cable breaks at broadband lambda probe terminals, allowing for continuous monitoring and detection of faults beyond traditional diagnosis modes, improving operational availability and reliability.
Implementation Method 1
a controlled pump current is conducted through the pump cell
Implementation Method 2
broadband lambda probe comprising a Nernst cell and a pump cell
Data Source
AI summary
A method for identifying cable faults at the terminals of a broadband lambda probe comprising a Nernst cell and a pump cell in the exhaust gas duct of an internal combustion engine. The broadband lambda probe has a reference electrode terminal RE, an internal pump electrode terminal IPE and an external pump electrode terminal APE. A pump current is applied to the broadband lambda probe and a pulsed reference pump current is applied to the broadband lambda probe. Cable faults are identified by the evaluation of potential swings in current.