Claw Fastening With Threaded Abutment Block

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Solution Overview

Problem

Existing fixing claws for electrical equipment in flush-mounting boxes face issues with deformation under strong tightening, rapid aging of elastic return means, complex and expensive spring-based solutions, and lack of reliable electrical insulation, leading to risks of damage and cable injury.

Innovation Solution

The use of a U-shaped claw with a threaded abutment block and a crimped stop block provides a rigid metal support for the claw, ensuring electrical insulation and withstanding high mechanical stresses, while a folded leaf spring ensures constant return force and easy assembly, and vertical grooves ensure complete retraction of the claws to avoid cable damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If strong tightening is applied to the clamping screw, then the clamping force on the claw is improved, but the synthetic material support deforms and may be damaged

Engineering Contradiction:
Improveclamping forceVSAvoidsupport strength
Core Design Contradiction:
ForceVSStrength

Solution Approach 1:

A metal abutment block is introduced as an intermediary element between the clamping screw and the synthetic material support. The screw clamps the metal block instead of directly pressing against the synthetic support, allowing high clamping forces to be transmitted through the metal block to the claw without deforming the synthetic support material.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If elastic return means are used for claw retraction, then the claw return function is provided, but the means age rapidly and are destroyed

Engineering Contradiction:
Improveclaw return functionVSAvoidreturn means durability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces long-lasting but complex spring mechanisms with a simple, inexpensive elastic band that can be easily replaced. The elastic band is designed as a sacrificial component that provides adequate service life and can be quickly swapped out when worn, avoiding the complexity and cost of durable spring systems.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If spring devices with blades riveted to claws are used, then claw return is achieved, but the solution becomes complex and expensive

Engineering Contradiction:
Improveclaw returnVSAvoidreturn mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of claw return from complex spring blade mechanisms and implements it through a simple elastic band that surrounds the equipment body. This eliminates the need for riveted blades, torsion springs, or other complex mechanical return devices, significantly simplifying the overall structure.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If metal fixing claws are directly in contact with the operating screw and equipment plate, then the structure is simplified, but electrical continuity exists creating safety risks

Engineering Contradiction:
Improvefixing structure simplicityVSAvoidelectrical shock risk
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The synthetic material support and metal abutment block serve as electrical insulators between the metal claws and the equipment plate. These intermediary components break the electrical continuity path, preventing electrical shock hazards while maintaining the mechanical fixing function. The design preserves structural simplicity while adding necessary electrical isolation.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This solution allows for secure, high-torque clamping without deformation, ensures precise maneuvering and mechanical strength, and provides perfect electrical insulation, protecting cables and operators during installation.

Implementation Method 1

a folded leaf spring ensures constant return force

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a crimped stop block provides a rigid metal support for the claw

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP1950858B1Fastening elements for installation devices by using claws
Publication Date: 2011.11.02 HAGER ELECTRO SAS
  • EP1950858B1 patent drawingFigure 1~2
  • EP1950858B1 patent drawingFigure 3~4

AI summary

The claw (2) has a threaded stop block (5) inserted in a support (1') of a body of a semi-recessed household electrical apparatus (1) for assembling the claw on the support. A locking screw (4) is locked in the body of the apparatus, where the block is constituted by a threaded hollow central body. The stop block extends outside the support for forming a rigid metallic bearing that supports and tilts the claw which is electrically isolated with respect to an apparatus support (11).