Oxygen Sensor Anomaly Detection via Signal Level Modification
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Solution Overview
Problem
Existing oxygen sensor systems for internal combustion engines face issues with anomaly detection, where temporary voltage fluctuations due to noise can lead to erroneous judgments, requiring additional signal lines for anomaly reporting, increasing complexity and cost, and limiting the information that can be provided.
Innovation Solution
An oxygen concentration detection system that uses a combination of an oxygen pump cell and an oxygen-partial-pressure detection cell, with a control circuit that maintains output voltage and detects anomalies by analyzing signal levels, allowing for anomaly reporting without additional signal lines by modifying existing signal levels, thereby reducing complexity and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional signal line is added for anomaly reporting, then anomaly detection capability is improved, but wiring complexity and system cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling existing signal lines to serve dual purposes: normal signal transmission and anomaly indication. The control circuit modifies signal levels on existing lines to encode anomaly information, allowing a single signal line to convey both measurement data and anomaly status without requiring dedicated anomaly reporting wires.
Solution Approach 2:
The patent changes signal parameters (voltage levels, pulse widths, or frequency characteristics) to encode anomaly information. By deviating from normal signal parameter ranges, the system indicates anomaly conditions using the same physical signal lines, thereby avoiding additional wiring while maintaining reliable anomaly detection.
2Loss of information
If signal lines are added for anomaly reporting, then anomaly information can be provided, but the number of input ports and system cost increase
Solution Approach 1:
Existing signal lines are made multi-functional to carry both normal operational signals and anomaly information. The control circuit encodes anomaly data by modifying parameters of signals already being transmitted, eliminating the need for separate input ports dedicated to anomaly reporting.
Solution Approach 2:
The patent merges anomaly information transmission with normal signal transmission by combining both functions into existing signal lines. This consolidation reduces the total number of input ports required while ensuring comprehensive anomaly information is conveyed to the control circuit.
3Reliability
If anomaly detection is performed based on voltage variation range, then anomaly can be detected, but noise causes erroneous judgments
Solution Approach 1:
The control circuit continuously monitors signal parameters and uses feedback mechanisms to distinguish between normal variations and actual anomalies. By comparing current signal characteristics against expected ranges and trends, the system can filter out noise-induced false positives while maintaining sensitivity to genuine anomaly conditions.
Solution Approach 2:
The patent employs multiple signal parameters (voltage, current, pulse width, frequency) for anomaly detection rather than relying solely on voltage variation. This multi-parameter approach increases the difficulty for noise to cause erroneous judgments, as simultaneous abnormal changes across multiple parameters are less likely to occur due to random noise.
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 configuration enables accurate anomaly detection and reporting without the need for extra signal lines, reducing wiring complexity, enhancing reliability, and allowing simultaneous judgment of anomalies with existing signal validation, thus reducing the load on the engine control unit.
Implementation Method 1
One of the cells is a pump cell which pumps oxygen out of a clearance (measurement chamber) between the cells and pumps oxygen into the clearance
Implementation Method 2
The other cell is an oxygen-partial-pressure detection cell which produces a voltage corresponding to the difference between a reference oxygen concentration and the oxygen concentration in the measurement chamber
Data Source
AI summary
An oxygen concentration detection system including an oxygen sensor which outputs a plurality of types of measurement signals and anomaly detection means and modification means. The anomaly detection means detects a sensor anomaly by determining whether the respective levels of the plurality of types of measurement signals fall within predetermined ranges. When a sensor anomaly is not detected, the modification means outputs the plurality of types of measurement signals as is. When a sensor anomaly is detected, the modification means outputs at least one of the plurality of types of measurement signals at a level outside the corresponding range within which the level of the measurement signal varies in a normal state.