Sanitary Fitting Nut With Torque-Limiting Thread Wings

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Solution Overview

Problem

Existing nuts for fastening sanitary fittings require significant effort to tighten and are prone to thread damage due to excessive torque, especially when made of plastic.

Innovation Solution

A nut design featuring a threaded insert with adjustable thread wings and torque-limiting notches that engage and disengage to prevent radial displacement and excessive torque, allowing for easy tightening with fewer turns and preventing thread damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the nut is made of plastic to reduce cost, then the cost is reduced, but the thread is easily damaged when tightened with excessive torque

Engineering Contradiction:
ImprovecostVSAvoidthread damage resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The torque-limiting mechanism uses a spring element that dynamically adjusts the engagement between the first and second torque-limiting notches. Under normal tightening torque, the notches remain engaged to transmit force. When excessive torque is applied, the spring compresses and allows the notches to disengage, automatically preventing thread damage while maintaining the plastic construction for cost-effectiveness.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The torque-limiting notches and spring mechanism are pre-configured in the nut design before installation. The spring is pre-compressed to a specific force, and the notches are positioned to engage at predetermined torque levels. This preliminary setup ensures that the torque limitation function is automatically activated during tightening without requiring additional control systems or operations.

Inventive Principle:
Principle #10Preliminary action

2Length of moving object

If the fitting shaft is long to reach through the carrier, then the fastening is achieved, but significantly more than 20 turns are required to tighten the nut

Engineering Contradiction:
Improvefitting shaft lengthVSAvoidtightening time
Core Design Contradiction:
Length of moving objectVSLoss of time

Solution Approach 1:

The threaded insert with thread wings acts as an intermediary component between the nut and the fitting shaft. The thread wings can be pushed outward radially during installation to engage with the fitting shaft thread, and then snap back inward to lock securely. This intermediary mechanism allows the nut to be tightened in significantly fewer turns (less than five turns) even with long fitting shafts, dramatically reducing the tightening time while maintaining secure fastening.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the thread wings are held in radial direction by the external thread, then the nut can be pushed onto the fitting shaft, but the thread wings must be bent outwards which requires force

Engineering Contradiction:
Improvepushing easeVSAvoidbending force
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The thread wings are designed with elastic properties that allow them to dynamically respond to applied forces. During installation, the thread wings can be pushed outward radially by applying force to engage with the fitting shaft thread. Once engaged, the elastic nature of the thread wings allows them to snap back inward automatically, locking the nut in place without requiring continuous force. This dynamic behavior reduces the overall force required during the installation process.

Inventive Principle:
Principle #15Dynamics

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

Enables sanitary fittings to be fastened with minimal effort while protecting the thread from damage by limiting torque to a safe threshold, ensuring secure attachment without damaging the nut or fitting shaft.

Implementation Method 1

the thread wings are designed to be flexible, in particular in the manner of tongues and/or on the threaded insert. When the sanitary fitting is fastened to a carrier, which can be a (work) board, for example, this allows the nut to be pushed onto a fitting shaft of the sanitary fitting designed as a threaded sleeve, for example. When pushed onto the fitting shaft, the thread wings are held in a radial direction by the external thread of the fitting shaft, i. H. orthogonal to the axis of rotation of the nut, bent outwards.

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

When the nut is tightened, the second oblique blocking surface of the lower part of the nut interacts with the first oblique blocking surfaces of the thread wings in such a way that the thread wings are prevented from being displaced outwards in the radial direction.

Methodology Applied
Scientific EffectMechanical interlocking: Mechanical Fastener

Implementation Method 3

at least one torque-limiting detent is formed on the lower part of the nut. When the nut is tightened, the at least one second torque-limiting notch engages with the at least one first torque-limiting notch of the lower nut part, so that a torque for tightening the nut can be transmitted from the upper nut part to the lower nut part. The first torque-limiting detent and/or the second torque-limiting detent are designed in such a way that they become detached from one another when the torque when tightening the nut exceeds a threshold value.

Methodology Applied
Scientific EffectTorque transmission and limitation: Torque

Data Source

PatentEP3786374B1Nut for fastening a sanitary fitting to a support
Publication Date: 2022.08.03 GROHE AG
  • EP3786374B1 patent drawingFigure 1~2
  • EP3786374B1 patent drawingFigure 3~4
  • EP3786374B1 patent drawingFigure 5~6

AI summary

A nut (1) for fastening a sanitary fitting (2) to a support (3), comprising at least: - a threaded insert (4) with a plurality of threaded wings (5) which, when the nut (1) is pushed onto a thread of the sanitary fitting (2), are adjustable outwards in a radial direction (6) and have a first inclined locking surface (7), - a nut lower part (8) with at least a first torque limiting notch (9) and a second inclined locking surface (10) which, when the nut (1) is tightened, interacts with the first inclined locking surfaces (7) of the threaded wings (5) in such a way that adjustment of the threaded wings (5) outwards in the radial direction (6) is prevented, and - a nut upper part (11) with at least a second torque limiting notch (12),which, when tightening the nut (1) to transmit a torque, engages with at least one first torque limiting notch (9) of the nut lower part (8) and disengages from at least one first torque limiting notch (9) of the nut lower part (8) when the torque exceeds a threshold value.