Crankshaft Sensor Reverse Rotation Detection
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Solution Overview
Problem
Current methods for detecting reverse rotation in internal combustion engines are costly and not efficient in all situations, often requiring specific sensors or correlation between crankshaft and camshaft signals, which are not universally applicable.
Innovation Solution
A method using a standard crankshaft sensor signal to detect reverse rotation by calculating the ratio R′(k) from the periods of tooth passages, eliminating the need for additional sensors or signal correlations, and determining the direction of rotation based on noteworthy values representative of normal and reverse rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specific type of sensors (voltage pulse or voltage level sensors) are used to detect direction of rotation, then reverse rotation detection capability is improved, but device cost increases
Solution Approach 1:
The patent makes the standard crankshaft sensor signal serve dual purposes: both determining angular position and detecting rotation direction. By analyzing the period ratios of the sensor signal itself, the system extracts direction information without needing separate sensors, making the existing sensor self-sufficient for both functions
Solution Approach 2:
The standard crankshaft sensor is made multi-functional by enabling it to perform both angular position detection and rotation direction detection. The processing unit analyzes the sensor signal's period characteristics to determine direction, allowing one sensor to replace what would traditionally require two different sensor types
2Reliability
If correlation between crankshaft sensor and camshaft sensor signals is used to detect reverse rotation, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the direction detection function from the complex task of correlating multiple sensor signals. By isolating and analyzing only the period ratios of the crankshaft sensor signal itself, the system achieves direction detection without needing to process or correlate camshaft sensor signals, simplifying the overall system
3Device complexity
If standard crankshaft sensor is used without additional sensors, then device cost is reduced, but reverse rotation detection capability is worsened
Solution Approach 1:
The patent changes the parameter analysis approach by examining the period ratios of the sensor signal rather than relying on voltage level or pulse width modifications. This parameter transformation enables direction detection from standard sensor signals that would otherwise be insufficient, extracting directional information from the temporal characteristics of the signal
Data Source
AI summary
A toothed target rotationally fixed to a shaft of the engine includes a series of n real teeth, followed by m dummy teeth forming a reference zone. For each tooth k, the period of time separating the latter from the preceding tooth k−1 is measured. A signal exhibits at least one transition in level in a portion of the signal corresponding to the passage of the reference zone. A first and a second product are calculated for at least some of the values of k; the ratio between these two products is calculated; and the direction of rotation of the engine is detected, in case of correspondence of the ratio with a first noteworthy value and with a second noteworthy value which are representative, respectively, of rotation in a normal direction and rotation in a reverse direction.