High Speed Pre-Ignition Detection via Knock Sensor Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High speed pre-ignition in engines, particularly above 4000 rpm, is difficult to detect due to mechanical engine noise, leading to potential engine degradation if left undetected.
Innovation Solution
A method using integrated knock sensor output in specific timing windows to differentiate and detect high speed pre-ignition, involving band pass filtering, rectification, and integration of sensor outputs over multiple engine cycles, allowing for accurate identification and mitigation through fuel injection suspension and intake air flow adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If knock sensor output is monitored in high speed ranges above 4000 rpm, then pre-ignition detection capability is improved, but mechanical engine noise interferes with measurement precision
Solution Approach 1:
The monitoring system divides the crank angle cycle into distinct timing windows: a pre-ignition detection window occurring before top dead center, and a knock detection window occurring after top dead center. This segmentation allows separate analysis of vibration signals in different temporal regions, enabling pre-ignition detection while excluding post-combustion knock signals and mechanical noise from the evaluation.
Solution Approach 2:
The system extracts only the vibration signal portion corresponding to the pre-ignition window from the overall knock sensor output. By isolating and analyzing only the signal segment occurring before top dead center, the system removes interfering mechanical engine noise and post-combustion vibrations from the detection process, improving measurement precision despite high-speed operating conditions.
2Reliability
If integrated knock sensor output is processed over multiple engine cycles, then detection reliability is improved, but response time for mitigation increases
Solution Approach 1:
The system integrates knock sensor output over multiple engine cycles in advance, building a cumulative reliability metric before pre-ignition events occur. This preliminary integration establishes a baseline detection confidence level, allowing the control system to trigger mitigation actions immediately once the pre-ignition threshold is exceeded, rather than requiring post-detection analysis.
Solution Approach 2:
The control system continuously monitors integrated knock sensor output and provides real-time feedback to the fuel injection and air flow control systems. When pre-ignition is detected through the integrated multi-cycle analysis, the feedback loop immediately activates mitigation strategies such as reducing fuel injection quantity or advancing spark timing, creating a closed-loop control system that responds rapidly to detected conditions.
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
Accurate detection of high speed pre-ignition reduces engine degradation and enhances performance by distinguishing it from low speed pre-ignition and mechanical noise, enabling timely remedial actions.
Implementation Method 1
one or more knock sensors arranged in, at, or along an engine block or coupled to engine cylinders. Output from the knock sensor generated in one or more of a first and second crank angle timing window may be used to identify abnormal combustion
Data Source
AI summary
Methods and systems are provided for improving the detection and mitigation of high speed pre-ignition. In one example, high speed pre-ignition is detected based on concurrent or sequential changes in an integrated knock sensor output in a knock window as well as a pre-ignition window. The high speed pre-ignition is addressed using cylinder fuel deactivation and/or engine load limiting to reduce the risk for run-away pre-ignition.