Engine Ignition Timing Control Using Knock Vibration Extraction
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Solution Overview
Problem
Existing techniques for determining knocking in internal combustion engines, such as Japanese Patent Laying-Open No. 8-4580, face challenges in accurately setting a background level for ignition timing control due to the inclusion of mechanical vibration, leading to improper ignition timing adjustments when knocking occurs or not.
Innovation Solution
A device that calculates a median value and standard deviation of vibration data, subtracts a product of the standard deviation and a constant from the median value to isolate mechanical vibration, and uses this to determine knock magnitude, allowing precise control of ignition timing based on the comparison with a predetermined value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the background level is set based on electric signal detected in vibration of internal combustion engine, then the background level includes effect of magnitude of vibration due to knocking, but knocking determination becomes inaccurate
Solution Approach 1:
The patent extracts and separates the mechanical vibration component from the total vibration signal by using statistical processing (median and standard deviation calculations) on vibration signals collected during idle operation. This allows the background level to represent only mechanical vibration without contamination from knocking vibrations, thereby resolving the contradiction between reliability and measurement precision.
2Quantity of substance
If the background level includes vibration due to knocking, then all vibration information is captured, but ignition timing control becomes improper
Solution Approach 1:
The patent extracts only the mechanical vibration component by performing statistical analysis (calculating median and standard deviation) on vibration signals acquired during idle operation when knocking is absent. This separated mechanical vibration background level is then used for accurate knock detection and ignition timing control, ensuring reliability without being contaminated by knocking vibrations.
Solution Approach 2:
The patent performs preliminary vibration signal collection and statistical processing during idle operation before actual engine operation begins. This preliminary action establishes an accurate background level that represents only mechanical vibration, which then serves as a reliable reference for subsequent knock detection and ignition timing control throughout engine operation.
3Adaptability or versatility
If vibration magnitude is corrected with engine speed, then capability of following engine speed variation is maintained, but background level still varies with knocking presence
Solution Approach 1:
The patent extracts the mechanical vibration component through statistical processing of vibration signals collected during idle operation. By separating mechanical vibration from knocking vibration in this manner, the resulting background level can be adapted to engine speed variations without being contaminated by knocking vibrations, thus maintaining both adaptability and reliability.
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 method effectively differentiates between mechanical and knocking-related vibrations, enabling precise determination of knocking presence and appropriate ignition timing adjustments, thereby improving engine operation.
Implementation Method 1
a knock sensor detecting vibration of an internal combustion engine and converting it into an electric signal level
Data Source
AI summary
An engine ECU executes a program that includes: calculating a median value and a standard deviation based on a calculated value based on the detected vibration of the engine; and subtracting a product of the standard deviation and a coefficient from the median value to calculate a magnitude of mechanical vibration specific to the engine. Knocking determination is carried out by comparing a knock magnitude calculated by dividing the magnitude value of the peak magnitude of the detected vibration of the engine by the magnitude of mechanical vibration specific to the engine with a predetermined determination value. Based on the knocking determination result, ignition timing of the engine is controlled.