Early Camshaft Position Detection Using Crankshaft Rotation Proxy
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Solution Overview
Problem
In four-stroke engines, determining the camshaft position is time-consuming due to the slower rotation of the camshaft, which can delay the detection of the crankshaft pulse wheel position, even with encoded systems.
Innovation Solution
A method and system for early camshaft position detection using a processor and memory to determine the crankshaft angular position based on electronic signals from sensors, identifying tooth types on the crank pulse wheel and calculating buffer values to differentiate between first and second crankshaft rotations, and utilizing bosses on the camshaft wheel to instantaneously determine the rotation without waiting for the camshaft to complete a full cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system waits for the camshaft to complete a full rotation to detect camshaft position, then the detection is accurate, but the detection time is delayed
Solution Approach 1:
The system performs preliminary detection of the camshaft position by monitoring crankshaft rotation and identifying camshaft position based on crankshaft-camshaft synchronization relationships before the camshaft completes a full rotation. This allows the system to determine camshaft position earlier by using the known rotational relationship (crankshaft rotates twice per camshaft rotation in four-stroke engines) and detecting crankshaft position as a proxy indicator.
Solution Approach 2:
The system uses the crankshaft rotation as an intermediary to indirectly detect camshaft position. Since the crankshaft and camshaft have a fixed synchronization relationship through timing chains or belts, monitoring the crankshaft's rotation provides information about camshaft position without requiring direct waiting for camshaft rotation completion.
2Measurement precision
If the system uses encoded crankshaft systems with multiple teeth, then the crankshaft position detection precision is improved, but the system complexity increases
Solution Approach 1:
The crankshaft pulley is segmented into multiple teeth with different characteristics (e.g., different numbers of teeth, different spacing, or different reflective properties). Each tooth or tooth pattern represents a specific angular position or rotational state. This segmentation allows the optical sensor to detect precise angular positions by identifying which tooth is currently in the detection zone, thereby achieving high-resolution position encoding without requiring complex mechanical structures.
Data Source
AI summary
Systems and methods for early camshaft position detection in an encoded crankshaft system are provided. In one embodiment, a method includes determining a crankshaft angular position of a crank pulse wheel based on electronic signals received from vehicle sensors. The crank pulse wheel is associated with a cycle including a first crankshaft rotation and a second crankshaft rotation. The method also includes determining a crankshaft angular position from electronic signals received from vehicle sensors. The method yet further includes receiving a sensed camshaft value for a camshaft wheel having a camshaft rotation in the cycle. The method then includes determining if the cycle is in the first crankshaft rotation or the second crankshaft rotation of the crank pulse wheel based on the crankshaft angular position of the crank pulse wheel and the sensed camshaft value.