Engine Knocking Detection Using Crank Angle Segmentation
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Solution Overview
Problem
Existing engine knocking detection methods often result in false positives due to noise interference from neighboring cylinders, leading to excessive ignition timing retardation, which affects fuel economy and vehicle drivability.
Innovation Solution
The method involves determining whether the knocking window and the end of injection overlap using crank angle signals, setting specific reference values for overlapping and non-overlapping ranges, and integrating knock signals to accurately determine knocking occurrences and adjust ignition timing accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the knock sensor detects vibration signals from neighboring cylinders during injector closing, then the detection sensitivity is improved, but false knocking detection increases
Solution Approach 1:
The knocking window is divided into multiple sub-windows based on crank angle positions. The first sub-window corresponds to the period when the injector of the current cylinder is closing, while the second sub-window corresponds to other periods. This segmentation allows the system to distinguish between vibrations caused by injector closing and actual knocking events.
Solution Approach 2:
Different reference values are assigned to different sub-windows within the knocking window. A first reference value is used for the first sub-window (injector closing period) and a second reference value is used for the second sub-window (other periods). This local differentiation enables the system to account for expected vibrations during injector closing while maintaining sensitivity to actual knocking.
2Reliability
If the ignition timing is retarded to prevent knocking, then the engine protection is improved, but fuel economy deteriorates
Solution Approach 1:
The system continuously monitors the integrated vibration signal and compares it against reference values to determine whether actual knocking has occurred. Based on this feedback, the control unit selectively retards ignition timing only when genuine knocking is detected, rather than continuously retarding it. This feedback mechanism prevents unnecessary ignition timing retardation and maintains fuel economy while still protecting the engine from actual knocking damage.
3Measurement precision
If the knock signal is integrated over the entire knocking window, then the detection accuracy is improved, but the response time increases
Solution Approach 1:
The knocking window is segmented into multiple sub-windows, and the knock signal is integrated separately within each sub-window. This allows the system to process vibration data in smaller, manageable segments rather than processing the entire window at once, thereby reducing the time required to reach a detection decision while maintaining 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 effectively reduces false knocking detections, preventing unnecessary ignition timing retardation and improving engine performance by differentiating between actual knocking and noise-induced signals.
Implementation Method 1
a knock sensor configured for detecting vibration in the cylinder
Implementation Method 2
a crank angle sensor configured for detecting a rotation angle of a crankshaft in the engine
Data Source
AI summary
A method for detecting knocking of an engine includes receiving a knock signal indicating a vibration level in a cylinder of the engine and a crank angle signal indicating a crank angle by which a knocking window and an end of injection (EOI) of an injector of the engine are expressed, determining whether the knocking window and the EOI overlap, based on the crank angle signal, setting a second reference value for an overlapping range within the knocking window overlapping the EOI by reflecting a predetermined level on a first reference value for a non-overlapping range within the knocking window non-overlapping the EOI depending on the determination, integrating the knock signal in the knocking window, determining whether an integrated value of the knock signal exceeds the first reference value in the non-overlapping range or the second reference value in the overlapping range, and retarding an ignition timing of the engine as a knocking avoidance logic depending on the determination.