Engine Misfire Detection Prohibiting Differential Locking Errors
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Solution Overview
Problem
Existing engine misfire detection methods based on rotational speed changes are prone to delayed or erroneous detection due to abrupt changes in load during differential locking, leading to incorrect misfire state identification.
Innovation Solution
An engine misfire detection device that includes an engine rotational speed change amount detector, a threshold setter, and a misfire detector, which prohibits misfire determination during differential locking state changes, using a misfire determination prohibition time set based on gear position, water temperature, and vehicle speed to accurately detect engine misfires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If misfire detection is performed based on engine rotational speed change amount, then misfire detection capability is improved, but erroneous detection occurs during differential locking state changes
Solution Approach 1:
The system performs preliminary detection of differential locking state changes using a state change detector before misfire determination is made. By detecting the differential locking state change in advance and prohibiting misfire determination during this period, the system prevents erroneous misfire detection while maintaining accurate misfire detection capability during normal operation.
2Stability of the object's composition
If constant time is required for misfire detection based on rotational speed change, then detection stability is improved, but detection delay occurs during abrupt load changes
Solution Approach 1:
The system dynamically adjusts misfire determination timing based on differential locking state. During differential locking state changes, misfire determination is prohibited temporarily to avoid erroneous detection. After the state change completes, misfire determination is resumed, ensuring both detection stability and timely response to actual misfire conditions.
3Device complexity
If vehicle body change amount detecting means is used for misfire detection, then dedicated sensor requirement is reduced, but detection accuracy decreases due to indirect measurement
Solution Approach 1:
The system uses the differential locking state as an intermediary indicator to prevent erroneous misfire detection. By detecting the differential locking state change (which causes abrupt load changes) and using this information to prohibit misfire determination during state transitions, the system achieves accurate misfire detection without requiring additional dedicated sensors.
Data Source
AI summary
An engine misfire detection device such that an engine misfire state can be accurately detected is obtained. The engine misfire detection device includes an engine rotational speed change amount detector that detects an engine rotational speed change amount, an engine rotational speed change amount threshold setter that sets a threshold with respect to the rotational speed change amount, and a misfire detector that compares the rotational speed change amount and the threshold, carries out a misfire determination on the engine when the rotational speed change amount exceeds the threshold, and carries out a misfire detection, wherein the misfire detector prohibits the misfire determination when a switching between a differentially locked state and an unlocked state is carried out.