Misfire Detection Adjusting for Exhaust Filter PM Accumulation
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Solution Overview
Problem
Conventional misfire detecting devices for internal combustion engines fail to accurately detect misfires that impair the exhaust purifying function of filters, particularly those with a honeycomb structure, due to particulate matter accumulation, leading to false negatives in misfire detection.
Innovation Solution
A misfire detecting device that estimates the amount of particulate matter accumulated on the filter and adjusts the misfire judgment value based on this accumulation, using a correction coefficient to set a smaller value as the particulate matter amount increases, thereby enhancing the accuracy of misfire detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the misfire judgement value is set based on operating condition only, then the device complexity is low, but the measurement precision of misfire detection deteriorates when PM accumulates on the filter
Solution Approach 1:
The invention changes the parameter of misfire judgement value from a fixed value based only on operating condition to a dynamic value that is corrected according to PM accumulated amount. The control unit adjusts the misfire judgement value by applying a correction coefficient based on the estimated PM accumulated amount on the filter, thereby improving detection accuracy without requiring a completely new detection system.
2Measurement precision
If the misfire judgement value is set to a smaller value to detect misfires with PM accumulation, then the measurement precision improves, but false detection increases when PM accumulation is not considered
Solution Approach 1:
The invention applies local quality by differentiating the misfire judgement criteria based on the local condition of PM accumulation on the filter. When PM accumulated amount is large, a smaller misfire judgement value is used to detect misfires that may be masked by PM combustion. When PM accumulated amount is small, the normal misfire judgement value is used to avoid false detections. This localized adjustment of judgement criteria improves both accuracy and reliability.
3Ease of operation
If the conventional misfire detection method is used, then the ease of operation is high, but the ability to detect misfires impairing filter exhaust purifying function deteriorates
Solution Approach 1:
The invention introduces feedback by using the estimated PM accumulated amount on the filter as feedback information to adjust the misfire judgement value. The control unit continuously monitors PM accumulation and uses this information to dynamically adjust the misfire detection threshold, enabling the system to adapt to changing filter conditions and accurately detect misfires that impair exhaust purifying function while maintaining ease of operation through automated adjustment.
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
The solution effectively suppresses false detection of misfires and increases the accuracy of identifying misfires that impair the exhaust purifying function of filters by adjusting the misfire judgment value according to the accumulated particulate matter, ensuring timely notification of engine abnormalities.
Implementation Method 1
estimate an amount of particulate matters accumulated on a filter for exhaust purification
Implementation Method 2
set a correction coefficient based on the accumulated amount; and set the misfire judgement value by multiplying the basic misfire judgment value by the correction coefficient
Implementation Method 3
when a predetermined judgement condition with the misfire judgement value is established, judge that a misfire having a level at which exhaust purifying function of the filter is impaired occurs
Data Source
AI summary
The occurrence of the misfire having a level at which exhaust purifying function of a catalyst is impaired (OT-level misfire) is detected. Upon the detection of the OT-level misfire, basic OT risk from the misfire is multiplied by a correction coefficient corresponding to the accumulated PM amount on the catalyst. The basic OT risk from the misfire is a basic value of OT risk from the misfire which is set based on the operating condition of the engine. The correction coefficient is set to a smaller value as the accumulated PM amount increases. Therefore, the OT risk from the misfire after the multiplication decreases as the accumulated PM amount increases. When a predetermined judgement condition with the OT risk from the misfire is established, it is judged that the misfire having the level occurs.