Misfire Detection Device Cylinder-Specific Determination Values
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Solution Overview
Problem
Existing misfire detection devices for internal combustion engines face challenges in accurately determining misfires when combustion control is deactivated in some cylinders, leading to potential deterioration of exhaust components and thermal degradation of aftertreatment devices.
Innovation Solution
A misfire detection device that sets different determination values for cylinders based on the deactivation process, using the magnitude of rotation fluctuation amounts and considering factors like load and rotation speed, to accurately determine misfires even when combustion control is deactivated in some cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If combustion control is deactivated in one or some of the cylinders, then fuel economy is improved, but misfire detection accuracy deteriorates due to rotation fluctuation differences
Solution Approach 1:
The determination value is dynamically adjusted based on the activation state of combustion control. When combustion control is deactivated in certain cylinders, the system automatically sets a different determination value that accounts for the expected rotation fluctuation differences, thereby maintaining accurate misfire detection while allowing fuel economy improvements through deactivation.
Solution Approach 2:
The system changes the determination parameter (determination value) based on the operational mode. By switching between different determination values depending on whether combustion control is active or deactivated in specific cylinders, the system adapts to varying rotational characteristics without compromising detection accuracy.
2Device complexity
If a single determination value is used for all cylinders, then device complexity is reduced, but misfire detection accuracy deteriorates when combustion control is deactivated
Solution Approach 1:
The determination value is segmented by cylinder based on their activation state. Cylinders with combustion control deactivated have distinct determination values from those with active combustion control, allowing accurate misfire detection in each group without requiring a complex unified model for all cylinders.
Solution Approach 2:
The determination value system serves multiple functions by adapting to different operational modes. The same misfire detection device can accurately detect misfires whether combustion control is active or deactivated, making the system universally applicable across different operating conditions without requiring separate detection systems.
Data Source
AI summary
A misfire detection device executes a deactivating process that deactivates combustion control for air-fuel mixture in one or some of cylinders and a deactivating process that determines whether a misfire has occurred. The determining process determines whether a misfire has occurred by evaluating a magnitude of a rotation fluctuation amount using a determination value independent from the rotation fluctuation amount. The determining process includes a deactivation-related setting process that sets a different determination value for each of first and second cylinders when the deactivating process is executed. The deactivating process has not been executed in the first and second cylinders. The rotation fluctuation amount is a change amount of an instantaneous speed variable. The instantaneous speed variable indicates a speed in a case in which a crankshaft rotates in a rotation angle region that is less than or equal to an occurrence interval of a compression top dead center.