In-Cylinder Pressure Sensor Deposit Removal via Controlled Knocking
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Solution Overview
Problem
Existing in-cylinder pressure sensor diagnosis methods often misdiagnose sensors as abnormal due to deposit accumulation, leading to unnecessary replacements, as the deposit adherence increases the spring constant of the sensor's diaphragm, reducing output values and degrading sensitivity.
Innovation Solution
An abnormality diagnosis device that performs a performance determination twice, with a deposit removal control in between, where knocking is intentionally caused to remove the deposit, ensuring accurate diagnosis by comparing estimated and actual pressure values, and adjusting EGR gas introduction to stabilize knocking across various engine operating ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If deposit removal control is executed to remove accumulated deposit inside combustion chamber, then measurement precision of in-cylinder pressure sensor is improved, but device complexity increases due to additional control operations
Solution Approach 1:
The system performs a first performance determination before executing deposit removal control, and then performs a second performance determination after the control. This preliminary action of checking sensor performance before and after deposit removal allows the system to distinguish between temporary output degradation due to deposits and actual sensor abnormalities, thereby improving measurement precision without unnecessarily increasing diagnosis system complexity
Solution Approach 2:
The in-cylinder pressure sensor serves dual purposes: it normally monitors combustion pressure and also performs self-diagnosis by comparing its output characteristics against predetermined thresholds. The sensor system essentially services itself by detecting its own performance degradation and triggering appropriate deposit removal control, reducing the need for external diagnostic equipment
2Reliability
If performance determination is performed multiple times with deposit removal control in between, then reliability of sensor abnormality diagnosis is improved, but loss of time increases due to additional determination cycles
Solution Approach 1:
The system implements periodic performance determination at predetermined intervals, with deposit removal control executed only when performance degradation is detected. This periodic approach ensures reliable diagnosis by systematically checking sensor status without continuously interfering with normal engine operation, thereby balancing diagnosis reliability with time efficiency
Solution Approach 2:
The system skips unnecessary deposit removal control operations by first determining whether performance degradation actually exists before executing the control. Only when the first performance determination indicates degradation below a threshold does the system proceed with deposit removal and subsequent re-evaluation, thus avoiding wasted time on unnecessary control cycles while maintaining high diagnosis reliability
3Manufacturing precision
If knocking is intentionally caused to remove deposit, then manufacturing precision of sensor performance is improved, but object-generated harmful factors increase due to knocking impacts
Solution Approach 1:
The system converts the harmful effect of deposit accumulation on sensor performance into a beneficial diagnostic opportunity. By detecting performance degradation and intentionally causing knocking to remove deposits, the system uses the harmful knocking phenomenon as a therapeutic measure to restore sensor output consistency. The harmful deposits become the target of removal, while the harmful knocking becomes the means to achieve benefit
Solution Approach 2:
The system changes operational parameters temporarily to induce knocking for deposit removal. By adjusting ignition timing or fuel injection parameters beyond normal operating ranges, the system creates controlled knocking conditions that generate sufficient mechanical impact to dislodge deposits from the sensor diaphragm, thereby restoring sensor performance without permanent damage to the engine
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 improves the accuracy of in-cylinder pressure sensor diagnosis, reducing unnecessary replacements and maintaining high determination accuracy by effectively removing deposits and accounting for engine speed and load variations.
Implementation Method 1
an in-cylinder pressure sensor exposed to the combustion chamber... the deposit adheres to a diaphragm of the in-cylinder pressure sensor
Data Source
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AI summary
An abnormality diagnosis device for an in-cylinder pressure sensor is provided. The device carries out a performance determination in which a performance quality of the sensor is determined based on an electric signal inputted from the sensor. The device carries out a first determination in which the performance determination is performed at a given timing, a performance recovery in which a given deposit removal control is executed in which a deposit accumulated inside the combustion chamber is removed when the performance quality of the in-cylinder pressure sensor is determined to fall below a given reference value, and a second determination in which the performance determination is carried out again after the performance recovery. In the second determination, the in-cylinder pressure sensor is diagnosed as abnormal when the performance quality of the sensor is determined to fall below the given reference value.