Misfire Detection Using Torsion Element Rigidity Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing misfire determination systems for internal combustion engines fail to accurately detect misfires due to resonance-induced rotational fluctuations caused by torsion elements, which are affected by manufacturing errors and chronological changes in the torsion element's rigidity, leading to inaccurate misfire detection.
Innovation Solution
A system that includes rotational speed detection sections for the output and downstream shafts, a rigidity estimation section that extracts frequency components from these speeds to estimate torsion element rigidity, and a misfire determination section that calculates a resonance influence component to accurately determine misfires by subtracting this component from the output shaft rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damper (torsion element) is interposed between the crankshaft and downstream shaft to control vibration, then vibration control is improved, but misfire detection accuracy deteriorates due to resonance-induced rotational fluctuations
Solution Approach 1:
The patent segments the rotational speed signal into multiple frequency components using Fourier analysis. By separating the resonance frequency component (caused by the damper) from other frequency components (including misfire signals), the system can independently analyze each component. This segmentation allows the misfire detection to proceed without interference from the damper-induced resonance, resolving the contradiction between vibration control and misfire detection accuracy.
2Measurement precision
If resonance frequency component is removed from rotational speed signal to improve misfire detection, then misfire detection accuracy is improved, but vibration control performance deteriorates
Solution Approach 1:
The patent introduces an intermediary processing step that calculates the resonance frequency component separately and uses it to correct the rotational speed signal for misfire detection purposes only. The original rotational speed signal containing the resonance component is preserved for vibration control, while a corrected signal (with resonance removed) is generated specifically for misfire detection. This intermediary approach allows both functions to operate optimally without compromising either vibration control or misfire detection accuracy.
3Measurement precision
If Fourier analysis is used to extract frequency components for misfire detection, then misfire detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies partial action by performing Fourier analysis only on the necessary frequency range and for the specific purpose of identifying resonance components. Rather than analyzing the entire spectrum in detail, the system focuses on extracting the resonance frequency component and using it to correct the rotational speed signal. This selective approach achieves the required misfire detection accuracy while minimizing computational complexity by avoiding unnecessary full-spectrum analysis.
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 precise estimation of torsion element rigidity and accurate misfire detection even with manufacturing errors or chronological changes, effectively distinguishing between misfire-induced and resonance-induced rotational fluctuations.
Implementation Method 1
fluctuation in torque of the crankshaft due to explosive combustion in the engine induces resonance of the torsion element and the downstream components including the torsion element. The resonance causes rotational fluctuation of the crankshaft
Data Source
AI summary
An internal-combustion-engine misfire determination system includes: detection sections that detects the rotational speeds of the output shaft and the downstream shaft; a rigidity estimation section that performs a rigidity estimation process in which frequency components caused by a resonance due to torsion of the torsion element are extracted from the rotational speeds, and the rigidity of the torsion element is estimated based on a value obtained by comparing amplitudes of both of the extracted frequency components and on the detected output shaft rotational speed; a resonance influence component calculation section that calculates a resonance influence component caused by an influence of the resonance on the output shaft rotational speed; and a misfire determination section that determines the occurrence of the misfire in the internal combustion engine based on a rotational speed for determination that is obtained by subtracting the calculated resonance influence component from the output shaft rotational speed.