Piston Target Sensor for Variable Compression Ratio Measurement
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Solution Overview
Problem
Variable compression ratio engines face challenges in accurately measuring the effective compression ratio due to inhomogeneous expansions, variations in operational clearances, and wear, leading to uncertainties and potential abnormal combustion issues.
Innovation Solution
A device that directly measures the effective compression ratio on the piston using a target passage sensor and crankshaft angular position sensor, with a computer calculating the piston's altitude at Top Dead Center, providing a more reliable measurement by reducing errors from component inhomogeneities and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sensor measures the position of the control rack to determine compression ratio, then the measurement system is simple, but the measurement accuracy deteriorates due to inhomogeneous expansions, clearance variations, and wear
Solution Approach 1:
The patent replaces the mechanical measurement system (control rack position sensor) with a direct optical/electronic measurement system. A sensor detects the position of a target fixed to the piston directly, eliminating the mechanical transmission chain (control rack, toothed wheel, etc.) that introduces measurement errors due to wear, clearance variations, and inhomogeneous expansions.
Solution Approach 2:
The patent introduces a target fixed to the piston as an intermediary element. This target serves as a direct reference point for the sensor, allowing the measurement system to capture the actual piston position without being affected by the mechanical transmission components between the piston and the original measurement point on the control rack.
2Measurement precision
If direct measurement on the piston is implemented, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent merges the measurement function directly with the piston component by fixing a target to it. This integration eliminates the need for separate measurement mechanisms and complex signal processing chains, as the sensor directly captures piston position information at the source, simplifying the overall system while improving accuracy.
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 solution significantly improves the accuracy of compression ratio measurement, reduces the risk of abnormal combustion, and optimizes engine performance by ensuring a more precise and reliable measurement of the effective compression ratio.
Implementation Method 1
at least one sensor fixed to the cylinder block of said engine which detects the passage of at least one target secured to the piston of said engine
Data Source
Figure 1
AI summary
The invention relates to a device for measuring the effective volumetric ratio of at least one cylinder in a variable compression-ratio engine, that comprises at least one target passage sensor (91) attached on the cylinder casing (100) and detecting the passage of at least one target (92) connected to the piston (2) of said engine, said target passage sensor interacting with at least one angular position sensor of the crankshaft (93) of said engine, and one calculator (94).