Misfire Detection Device for Internal Combustion Engine
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Solution Overview
Problem
Existing misfire detection systems for internal combustion engines face challenges in accurately determining misfires due to erroneous determinations caused by the influence of crankshaft rotation behavior and variations in rotation speed and load, particularly when combustion control is deactivated in specific cylinders.
Innovation Solution
A misfire detection device that uses a sensor to quantify the combustion variable, such as rotation fluctuation amount or in-cylinder pressure, and compares it with adjacent cylinders to determine if a misfire has occurred, employing a ratio-based approach to stabilize the determination threshold value and account for variations in engine speed and load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If combustion control is deactivated in specific cylinders to supply oxygen to the aftertreatment device, then the aftertreatment device can function properly, but erroneous misfire determination may occur due to changes in crankshaft rotation behavior
Solution Approach 1:
The patent extracts the deactivated cylinder from the misfire detection comparison process. When combustion control is deactivated in a specific cylinder, that cylinder is excluded from the divergence degree calculation. The system compares the determined cylinder only with adjacent cylinders that are not deactivated, preventing erroneous misfire determination caused by the intentional combustion deactivation in the aftertreatment oxygen supply process
Solution Approach 2:
The patent dynamically adjusts the misfire detection logic based on the combustion control state. The control device determines whether combustion control is deactivated in adjacent cylinders and modifies the divergence degree calculation accordingly. This dynamic adaptation allows the system to maintain accurate misfire detection while accommodating the changing operational modes of the engine for aftertreatment device management
2Measurement precision
If misfire determination is made by comparing with adjacent cylinders, then detection accuracy is improved, but erroneous determination occurs when adjacent cylinders have different combustion control states
Solution Approach 1:
The patent applies local quality by treating cylinders with different combustion control states differently in the comparison process. When an adjacent cylinder has deactivated combustion control, it is excluded from the divergence degree calculation for that specific determination. This localized adjustment ensures that comparisons are only made between cylinders with comparable operational states, preventing erroneous determinations while maintaining high detection accuracy
Data Source
AI summary
A misfire detection device and a misfire detection method for an internal combustion engine, and a memory medium are provided. Cylinders adjacent to the deactivated cylinder include a determined cylinder subject to a determination of whether a misfire has occurred and a cylinder different from the determined cylinder. It is determined that a misfire has occurred in the determined cylinder on condition that a divergence degree between a value of a combustion variable of the cylinder different from the determined cylinder and adjacent to the deactivated cylinder and a value of a combustion variable of the determined cylinder is greater than or equal to a specific amount. Combustion control has been executed in the cylinders adjacent to the deactivated cylinder and the cylinder different from the determined cylinder and adjacent to the deactivated cylinder.