Preignition Detection in Spark-Ignition Engines Using Vibration Retard
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Solution Overview
Problem
Existing methods for detecting preignition in spark-ignition engines, such as using ion current sensors or vibration sensors, face challenges in accurately distinguishing preignition from knocking, especially in early stages, leading to potential engine damage due to delayed detection.
Innovation Solution
A method involving a spark-ignition engine with a vibration sensor or in-cylinder pressure sensor that sets the spark timing on a retard side in low engine speed/high engine load regions, where the spark timing is adjusted based on threshold values of vibration intensity or pressure, and post-spark retard values are compared to pre-spark retard values to determine preignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion current sensors are used to detect preignition, then detection capability is provided, but accurate distinction from knocking is difficult leading to detection errors
Solution Approach 1:
The detection process is segmented into multiple stages: first detecting abnormal combustion using vibration intensity threshold, then performing spark timing retard, and finally determining preignition versus knocking by comparing maximum vibration values before and after retard. This segmentation allows accurate distinction between preignition and knocking that cannot be achieved by single-stage detection.
Solution Approach 2:
The method performs preliminary detection of abnormal combustion using vibration intensity threshold before conducting the definitive preignition determination. This preliminary action identifies candidates for further analysis, enabling early intervention while maintaining accurate distinction capability through the subsequent spark timing retard and comparison process.
2Device complexity
If vibration sensors are used for detection, then device complexity is reduced, but ability to detect mild preignition is insufficient
Solution Approach 1:
The method performs preliminary detection using vibration intensity threshold to identify abnormal combustion candidates. This preliminary action enables the system to catch mild preignition cases that would otherwise be missed, while maintaining device simplicity by using only a vibration sensor without requiring more complex sensors like ion current sensors for the final determination.
Solution Approach 2:
The method changes the parameter being measured by comparing maximum vibration values at different spark timing conditions (before and after retard). This parameter change approach allows mild preignition detection using simple vibration sensors by analyzing the differential effect of spark timing changes on vibration characteristics.
3Productivity
If spark timing is set on retard side in low engine speed/high load region, then engine performance is maintained, but preignition detection timing is delayed
Solution Approach 1:
The method performs preliminary detection of abnormal combustion using vibration intensity threshold before the engine operates at retarded spark timing. This preliminary action enables early identification of preignition candidates, allowing timely control operations to be executed even though the engine normally operates with retarded spark timing for performance optimization.
4Ease of operation
If traditional detection methods are used, then simple threshold comparison is possible, but early preignition detection is missed leading to engine damage
Solution Approach 1:
The method performs preliminary detection using a simple vibration intensity threshold comparison to identify abnormal combustion candidates. This maintains operational simplicity while enabling early preignition detection. The preliminary threshold check is followed by spark timing retard and maximum value comparison, which together provide reliable early detection without excessive complexity.
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 allows for early and accurate detection of preignition, distinguishing it from knocking, and enables timely control operations to prevent engine damage, even in mild preignition cases where traditional methods may fail.
Implementation Method 1
a vibration sensor for detecting vibration of the engine
Implementation Method 2
an in-cylinder pressure sensor for detecting an in-cylinder pressure of the engine
Implementation Method 3
a spark timing of a spark plug
Implementation Method 4
combustion of an air-fuel mixture
Data Source
AI summary
When a maximum value of vibration intensity (maximum vibration intensity)(Vmax) acquired from a vibration sensor (33) in a low engine speed/high engine load (operating region (R)) is equal to or greater than a given threshold value (X), a spark timing of a spark plug (16) is shifted from a point set in a normal state on a retard side with respect to a compression top dead center, farther toward the retard side. Then, when a maximum vibration intensity (Vmax2) acquired after the spark timing retard is greater than a maximum vibration intensity (Vmax1) acquired before the spark timing retard, it is determined that preignition occurs. This technique makes it possible to reliably detect preignition using the vibration sensor, while distinguishing the preignition from knocking. An in-cylinder pressure sensor for detecting an in-cylinder pressure of an engine may be used to determine the presence or absence of the preignition, in the same manner.