Hydraulic Cylinder Piston Rod Microcode for Absolute Position Sensing
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Solution Overview
Problem
Existing methods for accurately measuring the absolute position of a piston rod in hydraulic cylinders are limited by costly machining requirements, minimum stroke length limitations, and susceptibility to errors due to power outages or accumulation of measurement errors over time.
Innovation Solution
A method involving the formation of microstructures as a code on the piston rod's surface, using optical sensors to detect and decode these microstructures, allowing for precise determination of the piston rod's position through image analysis and application of offsets, independent of the rod's length and surface conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetostrictive or hall-effect based detectors are mounted to the cylinder, then absolute position measurement is achieved, but costly machining operations are required and minimum stroke length limitations apply
Solution Approach 1:
The patent replaces complex mechanical/magnetic detection systems (magnetostrictive or hall-effect detectors requiring costly machining) with a visual code system that can be detected by simple optical sensors, eliminating the need for expensive machining operations while maintaining measurement precision
Solution Approach 2:
The patent uses a visual code (pattern of marks or microstructures) as a simplified copy or representation of position information, which can be read by optical sensors without requiring complex physical detectors or extensive machining of the cylinder components
2Ease of manufacture
If relative position detectors are used, then cost is reduced, but errors accumulate over time and the first position must not be lost
Solution Approach 1:
The patent pre-encodes absolute position information directly into visual marks or microstructures on the piston rod surface. This preliminary encoding of position data allows the system to directly read absolute position without accumulation of errors, while using simple, low-cost optical detectors
3Measurement precision
If existing absolute position measurement methods are used, then position accuracy is achieved, but minimum stroke length and retracted length increase limitations are imposed
Solution Approach 1:
The patent encodes position information in the radial dimension (circumferential marks or microstructures on the piston rod surface) rather than requiring additional axial length. This allows absolute position measurement to be achieved without increasing the stroke length or retracted length of the cylinder
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 method provides accurate and reliable absolute position measurement of the piston rod with high precision and robustness against surface defects and errors, enabling real-time monitoring and operation at high speeds without significant length-dependent limitations.
Implementation Method 1
detecting the code comprises scanning the encoded surface with a sensor
Data Source
AI summary
A method for determining the position of a first part moving in relation to a second part in a system, comprising forming a code on a surface of the first part or the second part, yielding an encoded surface; detecting the code on the encoded surface; decoding the code; and determining the position of the moving part from the decoding of the code; the code comprises microstructures at precisely selected positions on the surface of the encoded part; detecting the code comprises scanning the encoded surface with a sensor in conditions selected in relation to the code formed and to the encoded surface to precisely read the code on the encoded surface.