Misfire Detection Device Adjusting Determination Thresholds
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Solution Overview
Problem
Existing misfire detection systems for internal combustion engines face challenges in accurately determining misfires due to variations in the frequency of provisional determinations relative to combustion control executions, leading to excessive or deficient official misfire determinations.
Innovation Solution
A misfire detection device and method that adjusts the official determination process based on the frequency and number of provisional determinations, taking into account the deactivating process's execution frequency and duration, using a sensor to output logical values and counting processes to define a specific period for official misfire determination, which includes extending or shortening the period and adjusting threshold values accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the deactivating process is executed frequently to regenerate the aftertreatment device, then the regenerating process effectiveness is improved, but the misfire detection accuracy deteriorates due to excessive provisional determinations
Solution Approach 1:
The system performs preliminary action by counting the number of deactivations of combustion control before making the official misfire determination. This allows the system to anticipate and compensate for the expected increase in provisional determinations during regeneration processes, thereby maintaining accurate misfire detection despite frequent deactivations
Solution Approach 2:
The control device uses feedback by continuously monitoring the relationship between deactivation count and provisional determination frequency. When the frequency exceeds the threshold indicating excessive determinations due to deactivations, the system adjusts its determination criteria accordingly, preventing false misfire conclusions while maintaining detection sensitivity
2Measurement precision
If the deactivating process is executed infrequently, then the misfire detection accuracy is improved, but the regenerating process effectiveness deteriorates
Solution Approach 1:
The system performs preliminary action by counting deactivations in advance and using this information to adjust the official determination criteria. This allows the system to maintain accurate misfire detection even when deactivations occur, while still permitting necessary regeneration processes to happen
Solution Approach 2:
The system changes parameters by dynamically adjusting the determination threshold based on the deactivation count. When deactivations are frequent, the threshold is adjusted to account for the expected increase in provisional determinations, thereby maintaining detection accuracy across varying operational conditions
3Device complexity
If the official determination uses a fixed frequency threshold, then the determination process simplicity is improved, but the misfire detection accuracy deteriorates due to variations in deactivation frequency
Solution Approach 1:
The system applies dynamics by making the determination threshold dynamic rather than fixed. The threshold is adjusted based on the actual deactivation count during the measurement period, allowing the system to adapt to varying operational conditions including different regeneration frequencies while maintaining accurate misfire detection
Solution Approach 2:
The system changes parameters by modifying the determination threshold based on deactivation frequency. This parameter adjustment allows the system to maintain detection accuracy across different operating scenarios without requiring complex alternative determination methods
Data Source
AI summary
A misfire detection device for an internal combustion engine is configured to execute: a deactivating process that deactivates combustion control for air-fuel mixture in one or some of cylinders; a provisional determination process that uses a detection value of a sensor to output a logical value indicating whether a misfire has occurred; a provisional determination counting process that counts a number of times a specific one of the logical value output by the provisional determination counting process has been output; and an official determination process that makes an official determination of whether the misfire has occurred using, as an input, the number of times counted by the provisional determination counting process during a specific period.