Lambda Probe Fault Simulator Nernst Voltage Modification
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Solution Overview
Problem
Existing fault simulators for broadband lambda probes in internal combustion engines can cause delayed reactions in engine control devices due to modifications in pump current, leading to undesired responses to real exhaust gas composition changes, especially in systems where no back-measurement of pump current occurs.
Innovation Solution
A fault simulator that modifies the Nernst voltage delivered to the control device based on the measured Nernst voltage from the broadband lambda probe, allowing for earlier simulation of pump current changes without interfering with real signal reactions, and enabling simulation of various faults such as delayed or distorted responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fault simulator modifies the pump current to simulate lambda probe faults, then the fault detection capability of the control device can be checked, but delayed reactions occur in the control device due to signal transit times
Solution Approach 1:
The patent introduces a fault simulator as an intermediary device between the broadband lambda probe and the engine control device. This mediator intercepts the Nernst voltage signal from the lambda probe, modifies it to simulate various fault conditions (such as aging effects, delayed responses, or distorted signals), and then forwards the modified signal to the control device. This allows the control device's fault detection capabilities to be tested without actually damaging the lambda probe, while avoiding the time delays associated with modifying pump current.
Solution Approach 2:
The fault simulator performs preliminary modification of the Nernst voltage signal before it reaches the control device. By pre-simulating fault conditions in the voltage signal itself, the system can immediately test the control device's diagnostic responses without waiting for pump current modifications to propagate through the system. This eliminates the time delay problem while maintaining accurate fault detection testing.
2Adaptability or versatility
If the pump current is modified to simulate faults, then fault scenarios can be generated, but undesired reactions occur to real exhaust gas composition changes
Solution Approach 1:
The fault simulator acts as an intermediary that separates fault simulation from the actual lambda probe and control device operation. It receives the authentic Nernst voltage signal from the lambda probe, overlays simulated fault characteristics (such as response delays or signal distortions typical of aging probes), and forwards the composite signal to the control device. This approach allows versatile fault scenario generation while maintaining signal accuracy, as the modifications are applied in a controlled manner rather than through physical pump current changes that interfere with real exhaust gas measurements.
3Measurement precision
If software or applications are modified to improve fault detection, then detection accuracy can be enhanced, but system complexity increases
Solution Approach 1:
Instead of modifying the control device's software or applications to improve fault detection, the patent creates a physical copy of the fault conditions through the fault simulator. The simulator replicates various lambda probe failure modes (such as slow response, signal distortion, or offset errors) by modifying the Nernst voltage signal in hardware. This allows comprehensive fault detection testing without changing any software, thereby maintaining system simplicity while achieving high measurement precision in fault detection 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
This approach prevents undesired reactions to real exhaust gas changes in the engine control device, allowing for accurate fault detection and simulation of different broadband lambda probe faults, including aging effects, without altering software or applications.
Implementation Method 1
In accordance with the Nernst principle, an electrical voltage, hereinafter referred to as the 'Nernst voltage' UN0, exists across the measurement cell, and is used to identify the concentration of oxidizing and reducing exhaust gas components in the cavity and in the reference gas.
Implementation Method 2
The sensor element of a broadband lambda probe has on the surface an opening through which exhaust gas enters. Adjacent to the entry opening is a porous layer through which the exhaust gas diffuses into a cavity. This cavity is separated from the external exhaust gas by an oxygen-ion-conducting electrolyte material.
Data Source
AI summary
A method for checking fault detection of a control device of an internal combustion engine for malfunction of a connected broadband lambda probe, including checking with a fault simulator between the lambda probe and the control device; to simulate faults of the broadband lambda probe, the fault simulator modifies electrical signals between the broadband lambda probe and the control device. A Nernst voltage of the lambda probe and a pump current of the control device are delivered to the fault simulator; the fault simulator delivers a pump current to the lambda probe and a Nernst voltage to the control device; to simulate faults of the lambda probe, the fault simulator modifies the Nernst voltage to the control device as to the Nernst voltage outputted from the lambda probe. Also described is a related fault simulator. The method and fault simulator monitor the fault detection of control devices for lambda probes.