Differential Cylinder Piston Coupling Ring Locking Against Loosening

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Solution Overview

Problem

Existing piston units for differential cylinders face issues with secure coupling between the piston and piston rod, particularly under dynamic loads and high operational pressures, where existing solutions either loosen or require costly and complex assembly/disassembly methods.

Innovation Solution

A differential cylinder-piston unit featuring a piston rod with an outer ring groove and a two-part coupling ring, combined with a resilient fixing ring, provides a secure axial fixation by forming a coupling ring groove space and utilizing a BOA spring ring for force transmission, allowing for easy assembly and disassembly without preload forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a two-part piston design with screw connection is used, then assembly is simplified, but the connection can loosen or come undone due to operating loads

Engineering Contradiction:
Improveassembly simplicityVSAvoidconnection security
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The coupling ring is divided into two separate parts (first and second coupling ring sections) that can be independently assembled into the outer ring groove, simplifying the assembly process while maintaining connection security through the resilient fixing ring

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fixing ring is designed with resilient properties (elasticity) that allow it to dynamically adapt to operating loads, maintaining constant contact pressure between the piston and piston rod under varying force conditions without loosening

Inventive Principle:
Principle #35Parameter changes

2Reliability

If locking elements are added to prevent loosening, then connection security is improved, but the risk of elements loosening or detaching increases

Engineering Contradiction:
Improveconnection securityVSAvoidcoupling structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fixing ring integrates multiple functions into a single component: it provides resilient contact for force transmission, acts as a retaining element to prevent detachment, and eliminates the need for separate locking elements by utilizing its elastic properties to maintain constant engagement under dynamic loads

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If metallurgical bond (welding) is used to prevent loosening, then connection security is improved, but thermal stress and complexity increase

Engineering Contradiction:
Improveconnection securityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The mechanical resilient contact of the fixing ring replaces the metallurgical bond (welding) to achieve permanent connection security, eliminating thermal stress and the need for specially qualified personnel while maintaining connection integrity under operating loads

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

4Reliability

If additional screw connections (locknuts or tension fittings) are used, then connection security is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveconnection securityVSAvoidcoupling structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fixing ring consolidates the functions of multiple screw connections (locknuts or tension fittings) into a single resilient element that provides both connection security and load accommodation without requiring additional fastening components

Inventive Principle:
Principle #5Merging (Combining)

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 ensures a completely secure and reliable connection, preventing loosening during operation, reduces machining complexity and costs, and allows for efficient assembly and disassembly, enabling the piston unit to handle high forces in both directions with minimal material and tooling requirements.

Implementation Method 1

a resilient fixing ring, provides a secure axial fixation by forming a coupling ring groove space and utilizing a BOA spring ring for force transmission

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3772604B1Differential cylinder piston unit
Publication Date: 2022.04.27 BUMACH ENG INT BV
  • EP3772604B1 patent drawingFigure 1
  • EP3772604B1 patent drawingFigure 2
  • EP3772604B1 patent drawingFigure 3

AI summary

The invention relates to a differential cylinder piston unit comprising a piston rod (1), a piston (2), a coupling ring (3), and a locking ring (4), wherein the piston rod (1) has an outer ring groove (5), wherein the piston (2) has an axial bore (2.1) in which the piston rod (1) is received, and an inner ring groove (6) open axially on one side towards a piston bottom end (2.2), wherein the inner ring groove (6) has a coupling ring section (6.1) and an adjacent locking ring section (6.2), and wherein the locking ring section (6.2) has an undercut contour (6.3), wherein the outer ring groove (5) and the coupling ring section (6.1) form a coupling ring groove space (7) in which the coupling ring (3) is arranged, wherein the coupling ring (3) is split and is divided by the coupling ring section (6.1) is radially enclosed and wherein the piston (2) is axially fixed on one side in a tensile direction by the coupling ring (3) on the piston rod (1), wherein the fixing ring (4) is arranged in the fixing ring section (6.2) between the undercut contour (6.3) and the coupling ring (3), wherein the fixing ring (4) is resiliently designed and engages in the fixing ring section (6.2) of the inner ring groove (6) in a relaxed position and wherein the fixing ring (4) has a flattened radial cross-section (4.2).