Cylinder-Integrated Distance Measurement for Accurate Piston Position

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Solution Overview

Problem

Conventional distance measuring devices for piston position detection in linear drives face challenges such as high installation costs, mechanical adjustments, and reduced accuracy due to external sensor mounting, which is prone to damage and logistical complexities, especially when dielectric properties of the medium fluctuate.

Innovation Solution

A distance measuring device that integrates a transmitting and receiving device with a line transition within the cylinder cover, using a measuring line to couple electromagnetic waves and evaluate the complex reflection factor, allowing for continuous, absolute distance measurement with high accuracy, and adjustable switching distances via an electronic interface, without external components or mechanical changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external magnetic sensors are mounted on the cylinder tube, then piston position detection is achieved, but installation costs and logistical effort increase due to mechanical adjustment and additional assembly requirements

Engineering Contradiction:
Improvepiston position detectionVSAvoidinstallation and assembly
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor device is integrated directly into the cylinder tube, merging the sensor mounting structure with the cylinder itself. This eliminates the need for separate external mounting brackets and reduces the number of assembly steps, while maintaining the ability to detect piston position through the cylinder wall

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cylinder tube itself serves as an intermediary structure that both contains the pneumatic/hydraulic medium and provides the mounting substrate for the sensor. This dual-function design eliminates the need for separate mounting structures and reduces overall system complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If additional sensors are installed to detect different positions, then more measurement points are available, but material, assembly, and installation costs increase

Engineering Contradiction:
Improvedetection positionsVSAvoidsensor quantity and assembly
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The integrated sensor device is designed to detect multiple piston positions through a single mounting structure. The sensor can identify different positions by detecting the piston's location at various points along its stroke, eliminating the need for multiple separate sensors while providing the same versatility

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sensor system is designed to dynamically track the piston's continuous movement and identify different positions along the stroke. This dynamic detection capability allows a single sensor to replace multiple static sensors, reducing assembly complexity while maintaining adaptability

Inventive Principle:
Principle #15Dynamics

3Reliability

If sensors are externally mounted on the cylinder, then accessibility and robustness can be ensured, but additional installation space is required and design effort increases

Engineering Contradiction:
Improvesensor accessibility and robustnessVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The sensor device is nested within the cylinder tube structure, utilizing the existing cylindrical space for sensor housing. This nested design eliminates the need for additional external mounting space while maintaining sensor accessibility through the cylinder wall for signal transmission

Inventive Principle:
Principle #7Nested doll (Nesting)

4Measurement precision

If conventional distance measuring devices are used, then piston position can be detected, but accuracy decreases when dielectric properties of the medium fluctuate due to temperature, pressure, or contamination

Engineering Contradiction:
Improvepiston position measurementVSAvoidmeasurement accuracy under varying conditions
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system incorporates a feedback mechanism that continuously monitors the dielectric properties of the medium and adjusts the measurement calculations accordingly. By measuring the change in dielectric properties and compensating for their effect on electromagnetic wave propagation, the system maintains accurate piston position measurements even when temperature, pressure, or contamination levels change

Inventive Principle:
Principle #23Feedback

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

Enables precise, continuous piston position measurement with reduced logistical effort and cost, integrating sensors within the cylinder cover, and accounts for changing dielectric properties of the medium, enhancing measurement accuracy and robustness.

Implementation Method 1

couple an electromagnetic wave into the line structure and to couple out the electromagnetic wave reflected on the reflection body from the line structure

Methodology Applied
Scientific EffectElectromagnetic wave propagation: Electromagnetic Induction

Implementation Method 2

measuring line for detecting material properties of the medium in the coupling area into the line structure to determine the distance

Methodology Applied
Scientific EffectDielectric properties measurement: Dielectric Permittivity

Implementation Method 3

evaluate the complex reflection factor between the coupled electromagnetic wave and the coupled out electromagnetic wave

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3069162B1Measuring device for determining a distance in a conducting structure
Publication Date: 2023.10.25 ASTYX GMBH
  • EP3069162B1 patent drawingFigure 1
  • EP3069162B1 patent drawingFigure 2
  • EP3069162B1 patent drawingFigure 3

AI summary

The invention relates to a distance-measuring device for determining a distance between a reflection body in a conducting structure and a coupling region for electromagnetic waves, which region is provided on an end section of the conducting structure, said measuring device comprising a transmitting and receiving device, and a conduction junction (1) provided on the coupling region, for coupling the transmitting and receiving device to the conducting structure containing a medium, in order to couple an electromagnetic wave into the conducting structure, and to decouple the electromagnetic wave, reflected on the reflection body, from the conducting structure. Said measuring device also comprises an evaluation device for determining the distance between the coupling region and the reflection body from the complex reflection coefficient between the coupled electromagnetic wave and the decoupled electromagnetic wave. The invention also relates to a corresponding method.