Engine Misfire Detection Using Frequency Analysis and Cylinder Cutoff
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Solution Overview
Problem
Existing methods for internal combustion engines fail to reliably and quickly identify ignition misfirings and subsequent cylinder identification, leading to increased vehicle exhaust emissions and potential damage to exhaust treatment systems.
Innovation Solution
A method involving the transformation of digital combustion signals into a frequency range using the discrete Hartley transform, allowing for the detection of ignition misfires through amplitude analysis, followed by sequential deactivation and reactivation of injection units to identify misfiring cylinders, utilizing existing sensor wheels without additional measuring units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If frequency analysis is used to detect misfirings, then misfiring recognition speed is improved, but cylinder identification capability deteriorates
Solution Approach 1:
The patent segments the misfiring detection process into two distinct phases: first using frequency analysis for rapid misfiring recognition, then sequentially deactivating individual injection units to identify the specific misfiring cylinder. This segmentation allows each phase to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent performs preliminary frequency analysis to detect the presence of misfiring before proceeding to cylinder identification. This preliminary action enables the system to quickly determine whether misfiring exists, then activates the more time-consuming sequential deactivation process only when needed for specific cylinder identification.
2Measurement precision
If sequential injection deactivation is performed for cylinder identification, then cylinder identification accuracy is improved, but system complexity increases
Solution Approach 1:
The system uses its own injection units as diagnostic tools by sequentially deactivating them and observing the effect on combustion characteristics. This self-service approach eliminates the need for additional diagnostic equipment or complex external measurement systems, achieving accurate cylinder identification using existing components.
3Reliability
If discrete Hartley transform is used for signal evaluation, then interference elimination is improved, but calculation intensity increases
Solution Approach 1:
The patent transforms the combustion signal from the time domain to the frequency domain using discrete Hartley transform, changing the parameter representation to separate useful low-frequency combustion information from harmful high-frequency interference. This parameter transformation enables reliable signal evaluation by filtering interference through frequency-based selection rather than complex time-domain processing.
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
Enables simple, quick, and reliable detection and identification of misfiring cylinders, reducing unburned fuel emissions and preventing damage to exhaust systems, applicable to both self-igniting and non-self-igniting engines, with adjustable reliability and correction for cyclic fluctuations and sensor faults.
Implementation Method 1
The discrete Hartley transform can be calculated exclusively by real operations. The measuring signal is decomposed into individual angular frequencies, which are also referred to as orders. Contrary to an evaluation of the measuring signal in the time region with the discrete Hartley transform higher-frequency interference portions in the measuring signal are automatically eliminated
Data Source
AI summary
The invention relates to a method for controlling the operating mode of an internal combustion engine (1) comprising several cylinders (3) and an injection system (4) with one injection unit (5) per cylinder (3). According to said method: a digital measuring signal, which characterizes the combustion of fuel (6) in the internal combustion engine (1), is first determined; said digital measuring signal is then transformed into a frequency range; a misfiring of the ignition is detected using the amplitude information of the transformed measuring signal and if a misfiring has occurred, the injection of the individual cylinders (3) is deactivated sequentially for a predefined period and for each cylinder the corresponding digital measuring signal that characterizes said cylinder is determined and transformed into the frequency range and a misfiring cylinder (3) is identified during the evaluation of the transformed measuring signal using the amplitude information. The invention also relates to a device for controlling the operating mode of an internal combustion engine (1) using a method of this type.