Flexible Shaft with Sinuous Helical Slots for Bidirectional Torque

Solution Overview

Problem

Existing flexible turning devices, such as screwdrivers and drills, with wire wound shafts have a preferred rotational direction, resulting in reduced torque when used in the reverse direction and axial stretch issues under torsional load.

Innovation Solution

A flexible turning device with a serpentine or sinuous helical slot design, allowing for flexibility and interlocking teeth that maintain torque transfer in both directions, formed by laser cutting or other precise techniques, and potentially filled with elastomeric material for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a wire wound flexible shaft is used, then the shaft can bend and reach confined spaces, but the shaft has reduced torque in reverse rotational direction and axial stretch under torsional load

Engineering Contradiction:

Improveaccessibility in confined spacesVSAvoidtorque in reverse direction

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The flexible shaft is divided into multiple rigid sections connected by flexible joints. Each joint contains interlocking teeth that engage to transmit torque bidirectionally. This segmentation allows the shaft to bend and reach confined spaces while maintaining torque transmission capability in both rotational directions through the toothed joint mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible shaft combines rigid metallic sections with flexible joint mechanisms featuring interlocking teeth. This composite structure integrates the bending capability of segmented construction with the torque transmission of toothed engagement, eliminating the axial stretch and reverse torque deficiency of wire wound shafts.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If a wire wound flexible shaft is used, then the shaft can bend and reach confined spaces, but the shaft experiences axial stretch under torsional load

Engineering Contradiction:

Improveaccessibility in confined spacesVSAvoidaxial length stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The flexible shaft is divided into multiple rigid sections connected by flexible joints. Each joint contains interlocking teeth that engage to transmit torque bidirectionally. This segmentation allows the shaft to bend and reach confined spaces while maintaining torque transmission capability in both rotational directions through the toothed joint mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a continuous wire wound structure that stretches axially under torsion, the invention inverts the approach by using discrete rigid sections with positive toothed engagement. The teeth interlock to prevent axial separation, converting the continuous flexible structure into a segmented rigid-flexible-rigid construction that resists axial stretch.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If a wire wound flexible shaft is used, then the shaft can bend and reach confined spaces, but the shaft has a preferred rotational direction reducing productivity

Engineering Contradiction:

Improveaccessibility in confined spacesVSAvoidscrew removal efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The flexible shaft is divided into multiple rigid sections connected by flexible joints. Each joint contains interlocking teeth that engage to transmit torque bidirectionally. This segmentation allows the shaft to bend and reach confined spaces while maintaining torque transmission capability in both rotational directions through the toothed joint mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible joints incorporate curved tooth profiles that allow smooth engagement and disengagement during bidirectional rotation. The curved geometry enables the shaft to flex and rotate in any direction without binding, providing equal torque transmission capability in both clockwise and counter-clockwise directions for efficient screw removal.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 device provides higher driving and reversal torque, reduced longitudinal extension or contraction, and improved accessibility in confined spaces, while maintaining structural integrity.

Implementation Method 1

The sinuous path forms interlocking teeth that, when transferring rotary motion, interlock with adjacent teeth while the body is unbent or bent about an axis

Methodology Applied

Scientific EffectMechanical interlocking: Mechanical Force

Implementation Method 2

The slots can also have an elastomeric material applied to one or more of the interior cavity, slot, exterior surface or inner surface

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10569396B2Flexible shaft for transfer of rotary motion

Publication Date: 2020.02.25 FLEX TECH INC

AI summary

A flexible shaft, having a first end and, a second end and capable of being bent about its axis while transferring rotary motion from a device to tool is disclosed. The shaft, manufactured from a rigid material, has at least one flexible segment having two sinuous slots ascending in a helical path from a common start point in opposite rotational directions. In other segments the slots can be a single helical slot, double helical slots, parallel or crossing, or circumferential. The helical paths can vary within each segment or from segment to segment.