Screw Coupling Clamping Ring for Fast Self-Locking Assembly

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Solution Overview

Problem

Screw couplings for high-pressure cleaning devices with single-start threads are time-consuming to assemble and difficult to handle due to the need for multiple revolutions, while multi-start threads are not self-locking and require expensive clamping surfaces for secure connections.

Innovation Solution

A coupling arrangement using a deformable clamping ring held by a dimensionally stable clamping ring holder, which adapts to the clamping surface of the other coupling arrangement upon screwing, providing a self-locking effect without the need for high dimensional accuracy, allowing for easy assembly and disassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If single-start threads are used, then the screw connection is self-locking and secure, but the assembly process becomes time-consuming and difficult to handle

Engineering Contradiction:
Improveself-locking capabilityVSAvoidassembly ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The thread structure is segmented into multiple starts (multi-start thread), where several thread turns run parallel to each other in a helical manner around the longitudinal axis. This segmentation allows the thread to achieve both self-locking capability and ease of assembly by distributing the load across multiple thread starts while maintaining a larger pitch angle for faster engagement.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If multi-start threads are used, then the assembly process becomes faster and easier, but the screw connection loses self-locking capability and may loosen unintentionally

Engineering Contradiction:
Improveassembly easeVSAvoidself-locking capability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

A clamping device with clamping surfaces is introduced as an intermediary element to provide the self-locking function. The clamping surfaces are designed as conical annular surfaces that are complementary to each other, creating a mechanical interference that prevents unintentional loosening while allowing the multi-start thread to maintain its ease of assembly advantage.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If clamping surfaces with high dimensional accuracy are used, then the screw connection becomes secure and self-locking, but the manufacturing cost increases significantly

Engineering Contradiction:
Improveclamping effectVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The clamping surfaces are designed with specific geometric parameters (conical shape with complementary angles) that create a self-centering and self-aligning effect during assembly. This parameter optimization allows the clamping surfaces to achieve reliable clamping with moderate dimensional tolerances, reducing manufacturing complexity and cost while maintaining the self-locking function.

Inventive Principle:
Principle #35Parameter changes

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 deformable clamping ring reduces production costs and ensures a secure, liquid-tight connection that prevents unintentional loosening, facilitating easier handling and maintenance of the screw coupling.

Implementation Method 1

a deformable clamping ring (56) which is held on a dimensionally stable clamping ring holder (52), and which adapts to the clamping surface (68) of the other coupling arrangement upon screwing

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3568626B1Coupling arrangement for screw coupling
Publication Date: 2023.05.03 ALFRED KARCHER SE & CO KG
  • EP3568626B1 patent drawingFigure 1
  • EP3568626B1 patent drawingFigure 2~3

AI summary

The invention relates to a coupling arrangement (12) for a screw coupling (10) for liquid lines of a high-pressure cleaning device, wherein the coupling arrangement (12) can be connected to a further coupling arrangement (14) of the screw coupling (10) in a liquid-tight manner and has a line piece (16), comprising a channel (18) for pressurised liquid, and wherein the coupling arrangement (12) has a multi-start thread (46) for screwing the coupling arrangement (12) to the further coupling arrangement (14), and wherein the coupling arrangement (12) has a clamping device (50) that can be clamped to a clamping surface (68) of the further coupling arrangement (14). To develop the coupling arrangement (12) such that it can be produced at lower cost, the invention proposes that the clamping device (50) has a dimensionally stable clamping ring holder (52) on which a clamping ring (56) is held, wherein the clamping ring (56) can be deformed by being pressed onto the clamping surface (68) of the further clamping arrangement (14) and can be adapted to the shape of the clamping surface (68). The invention also proposes a screw coupling (10) having a coupling arrangement (12) of this kind.