Engine Cylinder Pressure Estimation via Knocking Sensor Plausibility
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Solution Overview
Problem
Cylinder pressure sensors in internal combustion engines are prone to damage and signal deterioration due to thermal and mechanical loads, leading to unreliable operation and increased maintenance costs.
Innovation Solution
A method that combines the use of cylinder pressure sensors and knocking sensors to estimate cylinder pressure, with a plausibility check ensuring the accuracy of the cylinder pressure signal, allowing for continued operation even when the cylinder pressure sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cylinder pressure sensors are used to measure cylinder pressure, then measurement precision is improved, but reliability deteriorates due to sensor damage from thermal and mechanical loads
Solution Approach 1:
The patent combines cylinder pressure sensors with knocking sensors to create a redundant measurement system. The knocking sensor, which is more durable, serves as a backup for the cylinder pressure sensor, ensuring continuous reliable operation even when the primary sensor fails due to thermal and mechanical damage.
Solution Approach 2:
The system prepares for sensor failure by pre-installing a knocking sensor that can compensate for cylinder pressure sensor damage. This beforehand cushioning ensures that when the cylinder pressure sensor deteriorates, the system can continue to function without interruption, mitigating the reliability issue before it becomes critical.
2Reliability
If knocking sensors are used to determine cylinder pressure, then reliability is improved, but measurement precision deteriorates due to individual engine variations requiring adaptation
Solution Approach 1:
The patent merges the advantages of both sensor types by using the cylinder pressure sensor for high-precision measurements when functional and the knocking sensor for reliable backup. The control unit integrates signals from both sensors, selecting the appropriate data source based on sensor status and measurement requirements, thus achieving both precision and reliability.
Solution Approach 2:
The system uses feedback from the cylinder pressure sensor to continuously calibrate and optimize the knocking sensor's measurements. When the cylinder pressure sensor is operational, its data feeds back to improve the knocking sensor's accuracy, creating a self-adjusting system that maintains high precision while ensuring reliability through the knocking sensor's durability.
3Measurement precision
If high-quality cylinder pressure sensors are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines a high-precision cylinder pressure sensor with a durable knocking sensor in a unified measurement system. This merging allows the system to achieve high measurement precision through the cylinder pressure sensor while managing complexity by using the knocking sensor as a simplified backup mechanism, balancing accuracy and system manageability.
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 provides a reliable and accurate means of determining cylinder pressure, reducing the risk of engine malfunction and extending the operational life of internal combustion engines by using a failsafe estimated pressure when the sensor signal becomes unreliable.
Implementation Method 1
knocking sensors, which measure the structure-borne noise of the internal combustion engine and supply a corresponding representative knocking signal
Implementation Method 2
cylinder pressure sensors, which protrude into the combustion chamber of the internal combustion engine and are formed to provide a characteristic signal for the cylinder pressure prevailing in the combustion chamber
Data Source
AI summary
A method for operating an internal combustion engine, including collecting a knocking signal of a knocking sensor and collecting a cylinder pressure signal of a cylinder pressure sensor. The cylinder pressure signal is representative of a cylinder pressure prevailing in at least one combustion chamber of the internal combustion engine. The method further includes determining an estimated cylinder pressure on the basis of a model and the knocking signal, and subjecting the cylinder pressure signal to a plausibility check. The method further includes, if the cylinder pressure signal is not plausible according to the plausibility check, using the estimated cylinder pressure for the operation of the internal combustion engine.