Wireless Piston Position Sensor with Self-Powered Coil

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Solution Overview

Problem

Existing magnetic or inductive sensors for detecting piston positions in working cylinders are cumbersome, require extensive cabling, and are prone to failures due to line breaks, while wireless solutions are costly and inefficient in terms of space and energy usage.

Innovation Solution

A wireless magnetic sensor with a self-sufficient energy supply unit using a permanent magnet and energy converter magnet, which induces voltage in a coil as the piston moves, eliminating the need for cables and enabling compact, cost-effective operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wired sensors are used for detecting piston position, then power supply and signal transmission are reliable, but assembly and installation work is extensive and system availability decreases due to line breaks

Engineering Contradiction:
Improvesystem availabilityVSAvoidcabling complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the energy supply and signal transmission functions from external cables and integrates them into the sensor housing itself. The coil winding is arranged in the sensor housing to serve dual purposes: as part of the sensing mechanism and as an energy storage unit, eliminating the need for external connection lines and their associated vulnerabilities.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The coil winding performs multiple functions simultaneously: it acts as both the sensing element for detecting piston position and as an energy storage unit for powering the sensor. This multi-functionality eliminates the need for separate power supply cables and signal transmission lines, reducing device complexity while maintaining reliability.

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

2Device complexity

If wireless sensors with external energy supply are used, then cabling is eliminated, but space requirements and installation costs increase significantly

Engineering Contradiction:
Improvecabling requirementsVSAvoidspace for conductor loops
Core Design Contradiction:
Device complexityVSArea of stationary object

Solution Approach 1:

The energy storage coil is nested within the sensor housing structure itself, utilizing the existing spatial arrangement of the sensor components. The coil winding is integrated into the housing in such a way that it occupies minimal additional space while providing sufficient energy storage capacity, avoiding the need for large external conductor loops.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If conventional wired sensors are used, then power and signals can be transmitted reliably, but connection lines represent weak points for failures and tightness issues

Engineering Contradiction:
Improvesignal transmission reliabilityVSAvoidline breaks and connection failures
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the vulnerable connection lines entirely from the system by integrating the energy supply and signal transmission functions directly into the sensor housing. The coil winding serves as both the sensing element and energy storage unit, eliminating external cables that are prone to line breaks and connection failures.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The sensor becomes self-sufficient by using its own coil winding as the energy storage unit. The system serves itself by generating and storing energy internally through the coil, eliminating dependence on external power supply connections and their associated failure points.

Inventive Principle:
Principle #25Self-service

4Device complexity

If wireless sensors with large conductor loops are used for energy supply, then cables are eliminated, but radiated energy is very high and installation costs increase

Engineering Contradiction:
Improvecable eliminationVSAvoidradiated energy
Core Design Contradiction:
Device complexityVSUse of energy by stationary object

Solution Approach 1:

The energy storage coil is nested within the compact sensor housing, utilizing the existing magnetic field from the piston magnet efficiently. This nested arrangement creates a tight magnetic coupling that maximizes energy transfer efficiency while minimizing radiated energy, avoiding the high radiation associated with large external conductor loops.

Inventive Principle:
Principle #7Nested doll (Nesting)

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

The solution reduces assembly and installation work, minimizes downtimes, and allows for complete encapsulation, enhancing system availability and enabling new applications with freely movable sensors, particularly in harsh environments.

Implementation Method 1

When the piston moves, a force is exerted on the energy converter magnet via the piston magnet and the magnetic coupling

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

When the energy converter magnet, which is designed as a permanent magnet, is displaced within the coil, a voltage U is induced in the coil due to the associated change in magnetic flux dφ/dt

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2072961B1Sensor
Publication Date: 2013.05.15 SICK AG
  • EP2072961B1 patent drawingFigure 1~3
  • EP2072961B1 patent drawingFigure 4~6b

AI summary

The invention relates to a magnetic or inductive sensor comprising an electronic evaluation unit, wherein a piston of the working cylinder carries a piston magnet designed as a permanent magnet, the position of which can be detected by the evaluation unit, and wherein the evaluation unit can output a signal representing the piston position. To provide an improved sensor that can operate wirelessly, it is proposed that a power supply unit be provided for the evaluation unit, comprising at least one coil and at least one energy converter magnet designed as a permanent magnet, which is displaceable within the coil, and wherein the signal can be transmitted wirelessly from the sensor to a higher-level control system.