Working Cylinder Position Sensor With Single-Line Piston Contact

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Solution Overview

Problem

Existing hydraulic working cylinder position detection methods are complex and inaccurate, often requiring multiple wires and complex electronics for signal evaluation, leading to structural complexity and reliability issues.

Innovation Solution

A structurally simple and robust position sensor system for hydraulic working cylinders, featuring a base body with a pressure-connected interior, a contact unit with a rod-shaped contact body, and a spring element for precise mechanical and electrical contact with the piston unit, allowing for reliable position detection with a single signal line and high electromagnetic compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional position detection methods (mechanical switches, magnetic sensors, inductive proximity methods) are used, then position detection can be achieved, but the design complexity increases and electromagnetic interference occurs requiring multiple wires and complex evaluation electronics

Engineering Contradiction:
Improveposition detection precisionVSAvoidsensor structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of position detection by using a simple conductive ball contact that directly touches the piston rod, eliminating the need for complex magnetic fields, inductive circuits, or multiple sensor components. Only a single signal line is required to detect the position, removing unnecessary complexity while maintaining detection capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The conductive ball contact serves multiple functions simultaneously: it acts as the sensing element, the electrical contact, and the position indicator. The piston rod itself serves as the reference surface, eliminating the need for separate reference structures. This self-service approach reduces the number of components and simplifies the overall system

Inventive Principle:
Principle #25Self-service

2Reliability

If mechanical switch contacts or magnetic sensors are used for position detection, then position signals can be detected, but electromagnetic interference occurs and additional power and signal lines are required

Engineering Contradiction:
Improveposition signal reliabilityVSAvoidelectromagnetic interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electromagnetic sensing methods with a purely mechanical contact system. A conductive ball directly touches the piston rod to generate position signals, eliminating electromagnetic fields and their associated interference. The mechanical contact provides intrinsic immunity to electromagnetic interference while maintaining reliable signal detection

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses homogeneous conductive materials for the ball contact and piston rod interface, ensuring consistent electrical contact and signal generation. The entire position detection mechanism relies on the same physical principle (electrical contact through conductive materials), which simplifies the system and eliminates compatibility issues between different sensing technologies

Inventive Principle:
Principle #33Homogeneity

3Measurement precision

If complex evaluation electronics and multiple-wire cables are used, then position detection accuracy can be maintained, but the system becomes more complex and less robust

Engineering Contradiction:
Improveposition detection accuracyVSAvoidsystem robustness
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

Instead of using complex electronics to detect position and then processing signals through multiple wires and evaluation circuits, the patent inverts the approach by using a simple conductive contact that directly generates a position signal through mechanical touch. The simplicity of the contact mechanism inherently provides robustness while maintaining detection accuracy through direct physical contact

Inventive Principle:
Principle #13The other way round (Inversion)

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 provides precise and reliable piston position detection with reduced complexity, eliminating electromagnetic interference and the need for additional power and signal lines, ensuring accurate position signals even in challenging environments.

Implementation Method 1

a spring element for pressing the contact body against the piston unit in the direction of movement of the piston unit

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3919758B1Working cylinder and position sensor
Publication Date: 2024.03.20 BUMACH ENG INT BV
  • EP3919758B1 patent drawingFigure 1
  • EP3919758B1 patent drawingFigure 2
  • EP3919758B1 patent drawingFigure 3

AI summary

The invention relates to a working cylinder with a position sensor, comprising a cylinder body (1) forming a cylinder interior (2), an axially displaceable piston unit (3) having a piston movement space (4) arranged in the cylinder interior (2), and a position sensor (5) arranged on the cylinder body (1) comprising a base body (6) and a contact unit, wherein the base body (6) has a base body interior (8) which is pressure-connected to the cylinder interior (2), wherein the contact unit (7) is arranged insulated from the base body (6) and comprises a contact body (9), a contact element (12), and a spring element (13), wherein the contact body (9) penetrates the base body (6) in a pressure-tight manner and comprises a contact body connection section (10) and a contact body inner section (11), wherein the contact element (12) is electrically connected to and formed with the contact body (9).to come into contact with the piston unit (3), wherein the spring element (13) acts on the contact body (12), wherein the position sensor (5) is configured to assume a starting position and a working position, wherein in the starting position the spring element (13) is in a relaxed position and the contact body (12) is arranged at least section by section in the piston movement space (4) and wherein in the working position the contact body (12) is in contact with the piston unit (3), the spring element (13) is tensioned and the contact body connection section (10) is electrically connected to the piston unit (3).