Engine Misfire Detection Using Crankshaft Jerk and Type-Specific Thresholds
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Solution Overview
Problem
Traditional misfire detection systems in engines are not accurate enough, often incorrectly detecting engine misfires due to similarities in speed changes caused by misfires and rough road inputs, and use the same threshold for different types of misfires, leading to false detections.
Innovation Solution
A system that includes a threshold determination module and a misfire detection module, which determine acceleration and jerk thresholds based on misfire type, using crankshaft acceleration and jerk to differentiate between misfires and rough road inputs, and adjust thresholds for specific types of misfires to improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional misfire detection systems use a single threshold for all misfire types, then the system is simple to operate, but measurement precision deteriorates due to false detections from rough road inputs
Solution Approach 1:
The patent segments misfire detection into multiple categories (random misfire, single-periodic misfire, multiple-periodic misfire) with dedicated thresholds for each type. This segmentation allows the system to differentiate between various misfire patterns and rough road inputs by applying type-specific thresholds, thereby improving detection accuracy without excessive complexity
Solution Approach 2:
The patent implements dynamic threshold adjustment based on misfire type classification. Instead of using a fixed threshold, the system dynamically selects appropriate thresholds (first threshold for random misfire, second threshold for single-periodic misfire, third threshold for multiple-periodic misfire) based on the detected misfire pattern, enabling adaptive detection that improves precision while maintaining operational simplicity
2Measurement precision
If misfire detection systems use crankshaft acceleration and jerk analysis, then measurement precision improves for distinguishing misfires from road inputs, but device complexity increases
Solution Approach 1:
The patent introduces crankshaft jerk as an intermediary parameter to enhance misfire detection. By calculating the rate of change of crankshaft acceleration (jerk), the system creates an additional diagnostic layer that helps distinguish between misfire events and rough road inputs, improving measurement precision through a well-defined physical relationship rather than complex algorithms
Solution Approach 2:
The patent replaces complex signal processing or machine learning-based detection systems with a mechanics-based approach using crankshaft acceleration and jerk analysis. This substitution leverages fundamental mechanical principles to achieve accurate misfire detection while keeping the system relatively simple and computationally efficient
Data Source
AI summary
A system according to the principles of the present disclosure includes a threshold determination module and a misfire detection module. The threshold determination module determines at least one of an acceleration threshold and a jerk threshold based on a misfire type. The misfire detection module detects a misfire in a cylinder of an engine when: (i) crankshaft acceleration is less than the acceleration threshold; and/or (ii) crankshaft jerk is less than the jerk threshold. Crankshaft jerk is a derivative of crankshaft acceleration with respect to time.