Piston Position Detection Using Crank Angle Region Segmentation
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Solution Overview
Problem
Conventional methods for determining piston position in three-cylinder engines with low-resolution cam angle sensors face challenges in achieving accurate and stable detection, especially when combined with variable valve timing mechanisms.
Innovation Solution
A piston position determining apparatus and method that utilize a crank angle region to count cam angle signal generation frequency, allowing for precise determination of piston position based on the output pattern of cam angle signals, even with low-resolution sensors, by setting specific intervals for judging the number of cam angle signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low-resolution cam angle sensor is used to generate cam angle signals, then the device complexity is reduced and cost is lowered, but the measurement precision and reliability of piston position determination deteriorates
Solution Approach 1:
The determination of piston position is segmented into multiple evaluation stages: first determining the crank angle region, then counting cam angle signal generations within that region, and finally determining piston position based on the count pattern. This segmentation allows accurate position determination even with low-resolution sensors by evaluating signals over extended angular regions rather than requiring high-resolution single-point detection.
Solution Approach 2:
The invention performs preliminary determination of the crank angle region before counting cam angle signal generations. By pre-establishing the evaluation region based on crank angle position, the system prepares the framework for accurate piston position determination in advance, allowing the use of simpler sensors while maintaining precision through structured evaluation methodology.
2Measurement precision
If cam angle signals are generated at minute intervals to enable high-accuracy piston position determination, then the measurement precision improves, but the device complexity increases due to requiring high-resolution sensors
Solution Approach 1:
Instead of improving precision by increasing sensor resolution (one dimension), the invention transitions to evaluating cam angle signals across the crank angle region dimension. By counting signal generations over an extended angular range and evaluating patterns across multiple cylinders, the system achieves high precision through spatial-temporal pattern recognition rather than requiring high-resolution temporal sampling.
Solution Approach 2:
The system performs preliminary determination of the crank angle region before conducting the actual piston position determination. This preliminary action establishes the evaluation framework that allows subsequent accurate position determination using fewer, lower-resolution sensor signals, effectively preparing the measurement context in advance to reduce sensor requirements.
3Productivity
If the piston position determination is performed at each crank angle position in a three-cylinder engine, then the productivity and response speed improve, but the difficulty of detecting and measuring increases due to the need to identify specific cylinders at specific phases
Solution Approach 1:
The determination process is segmented into distinct phases: first determining the crank angle region, then counting cam angle signal generations within that region, and finally identifying the specific cylinder based on the count pattern. This segmentation breaks down the complex three-cylinder identification problem into manageable steps, reducing measurement difficulty while maintaining high determination speed.
Solution Approach 2:
The system uses feedback from the counted number of cam angle signal generations to determine piston position. By evaluating the pattern of signal generations within the crank angle region and comparing against expected patterns for different cylinders, the system automatically identifies the correct cylinder and phase, reducing manual intervention and complexity while maintaining high-speed determination.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high-accuracy determination of piston position and valve timing, ensuring stable detection precision even with low-resolution cam sensors, and allows for detection of valve timing variations in engines with variable valve timing mechanisms.
Implementation Method 1
using a sensor in which an electromagnetic pickup detects protruding portions disposed on a signal plate
Data Source
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AI summary
Detection of which of a plurality of reference angle positions a crankshaft of an engine arrives at is executed to subsequently determine a crank angle region in which an output pattern of a cam angle signal is determined, based on which of the plurality of reference angle positions the crankshaft arrives at, whereby determination of a piston position in each cylinder is made, based on the output pattern of the cam angle signal in the crank angle region.