In-Cylinder Pressure Sensor Phase Delay Diagnosis
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Solution Overview
Problem
Existing in-cylinder pressure sensor diagnosis methods fail to accurately detect failures, particularly phase delays caused by stretched or cracked supporting parts of the diaphragm, leading to incorrect diagnoses and potential engine performance issues.
Innovation Solution
A failure diagnosis device that includes an in-cylinder pressure sensor and an engine controller with a diagnosis module capable of reading signals within a specific crank angle range, determining a reference phase for pressure changes, and identifying phase delays exceeding a predefined threshold to diagnose sensor failures accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gain of the output value is used for diagnosis, then the diagnosis can detect material composition changes, but it cannot detect phase delays caused by supporting part failures
Solution Approach 1:
The patent transitions from one-dimensional gain-based diagnosis to two-dimensional diagnosis by adding phase analysis. The diagnosis module now evaluates both the gain (amplitude) and phase of the output signal, enabling detection of supporting part failures that cause phase delays without affecting gain.
Solution Approach 2:
The diagnosis function is segmented into multiple independent analysis components: gain analysis for detecting material composition changes and phase analysis for detecting supporting part failures. This segmentation allows each diagnostic aspect to be evaluated separately, improving overall diagnosis accuracy.
2Reliability
If only output waveform timing deviation is checked, then simple timing errors can be detected, but phase delays from sensor failures are misdiagnosed as normal variations
Solution Approach 1:
The system establishes a feedback mechanism where the diagnosis module continuously monitors the phase relationship between the output signal and the crank angle signal. When phase delay exceeds a predetermined threshold, the system provides feedback indicating sensor failure, distinguishing it from normal timing variations.
Solution Approach 2:
The patent introduces phase angle as a new diagnostic parameter alongside the existing gain parameter. By monitoring changes in the phase parameter specifically, the system can identify sensor failures that manifest as phase delays, while normal operating variations are filtered out using predetermined thresholds.
3Loss of information
If the diagnosis concludes normal operation based on waveform timing, then false alarms are reduced, but actual sensor failures are missed
Solution Approach 1:
The system performs preliminary phase analysis before concluding normal operation. By evaluating both gain and phase parameters against predetermined thresholds in advance, the system avoids false negatives while maintaining low false alarm rates.
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
The solution enhances the accuracy of in-cylinder pressure sensor failure diagnosis, enabling timely detection of issues such as diaphragm stretching or cracking, thereby improving engine performance and reducing false diagnosis rates.
Implementation Method 1
an in-cylinder pressure sensor SW6 disposed so as to face the inside of a combustion chamber of a reciprocating engine, and outputting a signal corresponding to a pressure inside the combustion chamber
Data Source
AI summary
A failure diagnosis device for an in-cylinder pressure sensor is provided, which includes an in-cylinder pressure sensor, and an engine controller comprised of circuitry configured to execute a diagnosis module into which a signal of the sensor is inputted, to diagnose a failure of the sensor based on the signal. The diagnosis module includes a reading module configured to read the signal of the sensor within a specific crank angle range, a reference phase determining module configured to determine a reference phase that is a phase of a pressure change accompanying a volume change of the combustion chamber, and a failure determining module configured to determine that the sensor has failed, when the failure determining module determines a phase of the read signal of the sensor is delayed by an amount exceeding a predefined threshold from the determined reference phase.