Counter-Threaded Locking Fastener Assembly for Vibration Resistance

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Solution Overview

Problem

Conventional fasteners fail to effectively prevent loosening in dynamic environments due to vibrations and other external factors, despite the use of spring washers and other locking mechanisms.

Innovation Solution

A multi-piece locking fastener system featuring counter-threaded profiles, where a first screw with a hollow shaft and a second screw with opposite thread patterns are used in conjunction with an intermediate component, preventing loosening by their counter-threaded orientations, and optionally including a thickened base layer with counter-threaded passageways for additional security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional threaded fasteners are used, then the fastening operation is simple, but the fasteners fail to prevent loosening under vibrations and dynamic loads

Engineering Contradiction:

Improveresistance to looseningVSAvoidfastener structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fastening system is divided into multiple independent components: an outer fastener with exterior threads engaging the intermediate component, and an inner fastener with opposite threads engaging the hollow shaft of the outer fastener. This segmentation allows each component to contribute to vibration resistance independently, creating a multi-layered locking mechanism that prevents loosening under dynamic loads.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner fastener is nested within the hollow shaft of the outer fastener, with the inner fastener's opposite threads engaging the outer fastener's interior threads. This nested configuration creates counteracting forces that lock the assembly together, preventing either fastener from loosening while maintaining a compact overall structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If counter-threaded fasteners are used to prevent loosening, then vibration resistance improves, but the manufacturing complexity increases

Engineering Contradiction:

Improvevibration resistanceVSAvoidthreading complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using complex locking mechanisms on single-direction threads, the invention uses opposite thread directions (right-hand and left-hand threads) to create self-locking behavior. When vibrations occur, the counter-rotating forces generated by the opposite threads press the fasteners tighter against the intermediate component, converting the harmful vibration energy into a beneficial locking force.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention changes the thread direction parameter from uniform to opposite directions between the outer and inner fasteners. This parameter change creates differential rotational responses to vibration forces, generating counteracting moments that prevent loosening. The hollow shaft configuration of the outer fastener enables this parameter change while maintaining structural integrity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a multi-piece fastening system is implemented, then loosening prevention improves, but the assembly time increases

Engineering Contradiction:

Improvefastener securityVSAvoidassembly time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The outer fastener is installed first and positioned against the intermediate component, with its hollow shaft already in place. The inner fastener is then inserted through the hollow shaft and engaged with the counter-threads. This preliminary positioning of the outer fastener's hollow shaft simplifies the subsequent installation of the inner fastener, reducing overall assembly time despite the multi-component nature of the system.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The hollow shaft of the outer fastener serves multiple functions: it provides structural support, guides the inner fastener during installation, and provides the threaded engagement surface for the inner fastener. This multi-functionality reduces the need for separate guiding or alignment features, streamlining the assembly process while maintaining fastener security.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11236778B2Multi-piece anti-vibration locking fastener having coaxially arranged inner and outer opposite threaded bolts in combination with successive and opposite threaded profiles within a thickened base layer

Publication Date: 2022.02.01 SIZE JR EARL ALLEN

AI summary

A multi-piece locking fastener assembly including a thickened base layer having a first wider diameter passageway exhibiting a first interiorly threaded orientation and a second narrower diameter passageway exhibiting a second opposite threaded orientation and extending a distance in communication with and beyond a bottom end wall of the first wider passageway. A first bolt fastener has a first arrangement of exterior threads engageable with the wider diameter passageway of the base layer. The first fastener further includes an interior passageway. Following installation of the wider fastener into the base layer, a second narrower diameter bolt fastener having at least a partially threaded stem is threadably inter-engaged with the second passageway in the base layer to prevent loosening of either fastener via their counter-threaded orientations.