Snap-Fit Adapter with Tapered Threads for Valve Retention Force

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Solution Overview

Problem

Snap-fit connections in thermostatic radiator valve assemblies provide limited retention force, leading to unintentional disconnections of the thermostatic control device from the radiator valve arrangement.

Innovation Solution

An adapter with a tubular shape featuring a snap-fit connection at one end and a threaded connection at the other, utilizing a resilient interlocking part and tapered male threads to enhance retention force by preventing radial expansion when engaged with both the valve arrangement and control device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a snap-fit connection is used to attach the control device to the valve arrangement, then the attachment process is simple and quick, but the retention force is limited and unintentional disconnections may occur

Engineering Contradiction:
Improveease of attachmentVSAvoidretention force
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The adapter is divided into two distinct connection interfaces: a snap-fit connection at the first axial end portion for simple attachment, and a threaded connection at the second axial end portion for secure retention. This segmentation allows each connection type to fulfill its optimal function - the snap-fit provides quick installation while the threaded connection provides high retention force.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adapter serves as an intermediary component between the control device and the valve arrangement. It translates the simple snap-fit connection into a secure threaded connection, effectively converting a low-retention interface into a high-retention interface while maintaining ease of attachment.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the first interlocking part is made resilient to enable snap-fit engagement, then the attachment is easy and self-locking, but the retention force is reduced due to radial expansion

Engineering Contradiction:
Improveself-locking attachmentVSAvoidretention force
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The resilient first interlocking part is segmented into multiple radial sections that can expand independently during snap-fit engagement. This segmentation allows the interlocking part to achieve self-locking through radial expansion while maintaining sufficient retention force through the distributed engagement points.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adapter employs different local qualities at different axial positions: the first axial end portion has a resilient interlocking part for easy snap-fit engagement, while the second axial end portion has rigid threaded connections for high retention force. This local differentiation resolves the contradiction between ease of operation and retention force.

Inventive Principle:
Principle #3Local quality

3Reliability

If tapered male threads are used to prevent radial expansion, then retention force is increased, but the attachment process becomes more complex

Engineering Contradiction:
Improveretention forceVSAvoidattachment process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The attachment process is segmented into two distinct phases: first, the snap-fit connection provides immediate self-locking attachment; second, the threaded connection provides enhanced retention force. This segmentation allows the system to achieve high reliability without requiring a single complex attachment mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The snap-fit connection performs a preliminary attachment action that positions and secures the adapter to the valve arrangement before the threaded connection is engaged. This preliminary action simplifies the overall process by establishing a pre-aligned, self-locking base that makes the subsequent threaded engagement straightforward.

Inventive Principle:
Principle #10Preliminary action

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 adapter significantly increases the retention force of the snap-fit connection, preventing unintentional disconnections while maintaining ease of attachment, without requiring additional components or steps.

Implementation Method 1

The first interlocking part is movable in a resilient manner in a radial direction such that, when the adapter becomes engaged with the valve arrangement, the first interlocking part expands in the radial direction and thereafter snaps back in the radial direction to form the snap-fit connection

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The male threads are configured to enable the first interlocking part to become pressed inwards in the radial direction when the adapter becomes engaged with the control device via the threaded connection and thereby preventing the first interlocking part from expanding in the radial direction

Methodology Applied
Scientific EffectMechanical constraint through tapered threads: Wedge

Data Source

PatentEP4484833B1An adapter for attaching a control device to a valve arrangement
Publication Date: 2025.10.22 IMI HYDRONIC ENG INT SA
  • EP4484833B1 patent drawingFigure 1
  • EP4484833B1 patent drawingFigure 2A~2B
  • EP4484833B1 patent drawingFigure 3A~3B

AI summary

An adapter (100, 200) for attaching a control device (140, 240) to a valve arrangement (120, 220). The adapter (100, 200) is configured to engage with the valve arrangement (120, 220) via a snap-fit connection, and to engage with the control device (140, 240) via a threaded connection. The snap-fit connection is formed by a first interlocking part (203a, 203b) provided on an inside (202) of the adapter (100, 200) engaging a second interlocking part (222a, 222b) of the valve arrangement (120, 220) such that the adapter (100, 200) is retained to the valve arrangement (120, 220). The first interlocking part (203a, 203b) is movable in a resilient manner in a radial direction (R) such that, when the adapter (100, 200) becomes engaged with the valve arrangement (120, 220), the first interlocking part (203a, 203b) expands in the radial direction (R) and thereafter snaps back in the radial direction (R) to form the snap-fit connection. The adapter (100, 200) is provided with male threads (211) arranged circumferentially with respect to the axial direction (A). The threaded connection is formed by the male threads (211) engaging female threads (241) of the control device (140, 240) such that the adapter (100, 200) is retained to the control device (140, 240). The male threads (211) are tapered towards the second axial end portion (210) of the adapter (200) to enable the first interlocking part (203a, 203b) to become pressed inwards in the radial direction (R) when the adapter (200) becomes engaged with the control device (240) via the threaded connection and thereby preventing the first interlocking part (203a, 203b) from expanding in the radial direction (R) when the adapter (100, 200) is engaged with the control device (140, 240) via the threaded connection.