Protective Cap Assembly for Sealed Underwater Screw Threads

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Solution Overview

Problem

Existing fastening screws in underwater applications face issues with surface corrosion, contamination, and damage to the protruding thread due to seawater and marine organisms, necessitating frequent replacement and inadequate protection from environmental elements.

Innovation Solution

A protective cap with a cylindrical body and through-hole design that securely attaches to the screw using a screw, featuring internal seals and lubrication to prevent contamination and corrosion, ensuring easy assembly and disassembly while maintaining a clean thread surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a protective cap is simply slid onto the mounting screw, then the assembly is simple, but the connection security is insufficient for underwater applications

Engineering Contradiction:

Improveassembly simplicityVSAvoidconnection security

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The protective cap is divided into a cap body and a separate securing screw. The cap body slides onto the mounting screw for easy assembly, while the securing screw threaded into the cap body provides reliable fixation. This segmentation allows the cap to be easily assembled yet securely fixed in underwater conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The securing screw acts as an intermediary element between the protective cap and the mounting screw. It provides the mechanical connection that ensures reliable fixation, while allowing the cap itself to remain a simple sliding component for easy assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If special coatings are applied to fastening screws, then corrosion protection is improved, but the coating can be easily damaged during tightening and cannot be repaired in underwater applications

Engineering Contradiction:

Improvecorrosion protectionVSAvoidcoating repairability

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The protective cap provides beforehand cushioning by enclosing and protecting the mounting screw from corrosive seawater and mechanical damage during tightening operations. This preventive protection eliminates the need for repairable coatings, as the cap itself serves as the primary protection barrier.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The protective cap serves as a disposable or replaceable component that protects the mounting screw. Instead of relying on durable but repairable coatings, the cap provides complete protection and can be replaced if damaged, which is more economical than repairing coatings in underwater applications.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If the protruding thread is exposed to seawater, then the screw can be easily installed, but the thread becomes subject to surface corrosion and contamination

Engineering Contradiction:

Improveinstallation easeVSAvoidthread corrosion and contamination

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The harmful exposure of the thread to seawater is extracted by enclosing the thread within the protective cap. The cap can be easily installed by sliding over the screw, while simultaneously extracting the thread from the corrosive environment, protecting it from contamination.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The protective cap acts as a flexible shell that encloses the mounting screw thread. This shell provides complete protection from seawater corrosion and contamination while allowing for easy installation through simple sliding onto the screw.

Inventive Principle:

Principle #30Flexible shells and thin films

4Reliability

If existing protective caps are used, then some protection is provided, but they do not provide sufficient sealing against underwater environmental elements

Engineering Contradiction:

Improveprotection levelVSAvoidseawater penetration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective cap is designed as a sealed shell structure that completely encloses the mounting screw. The cap body forms a closed environment that prevents seawater penetration, providing sufficient sealing against underwater environmental elements while maintaining reliable protection.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentEP4474660B1Protective cap

Publication Date: 2026.03.04 AB SKF SKF PATENT DEPARTMENT

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AI summary

A protective cap (1) for a fastening screw (2) is disclosed, wherein the protective cap (1) has a cylindrical body with an inner and an outer lateral surface (23), wherein the cylindrical body is closed at one end and can be slid onto the fastening screw (2) with the other, open end, wherein the inner lateral surface forms an inner recess in which the fastening screw (2) can be received, wherein a through-hole (12) is provided at the closed end through which a screw (10) can be passed, wherein the screw (10) is designed to engage in a corresponding borehole (14) in the fastening screw (2) in order to connect the protective cap (1) to the fastening screw (2).