Nut With Flexible Fingers and Radial Compression

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Prior lead screw assemblies with nuts having flexible fingers experience significant stick slip due to the conversion of axial force into radial force, limiting their functionality and ability for infinite compensation.

Innovation Solution

A nut design featuring a base with axially extending flexible fingers, radial compression members, and axial locator structures, such as circumferential grooves, that apply a constant radially inward compressive force to the flexible fingers, reducing stick slip by maintaining a precise interface with the lead screw without converting axial force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If axial force is used to bias the inclined ramp against the rib/projection to create radial force, then the flexible fingers can engage the lead screw, but significant stick slip occurs due to the large ramp angle required

Engineering Contradiction:

Improveradial engagement forceVSAvoidstick slip reduction

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

Instead of converting axial force to radial force through an inclined ramp (traditional approach), the patent inverts the approach by directly applying radial compression force through compression members that act radially inward on the flexible fingers, eliminating the need for axial-to-radial force conversion and the associated large ramp angles that cause stick slip

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces compression members as intermediary elements that directly apply radial compressive force to the flexible fingers. These compression members act as mediators between the nut structure and the flexible fingers, providing the necessary radial engagement force without requiring the problematic inclined ramp mechanism

Inventive Principle:

Principle #24Intermediary (Mediator)

2Force

If a large ramp angle is used to create sufficient radial force, then the flexible fingers can engage the lead screw, but the interface experiences significant stick slip that reduces functionality

Engineering Contradiction:

Improveradial forceVSAvoidfunctionality and infinite compensation

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

The patent eliminates the inclined ramp mechanism entirely and directly applies radial compression force through compression members. This inverts the traditional force application approach, allowing sufficient radial engagement force to be achieved without the large ramp angles that cause stick slip and limit operational functionality

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the nut structure is designed with flexible fingers and compression members, then constant radial compressive force is applied to reduce stick slip, but the device complexity increases

Engineering Contradiction:

Improveconstant engagement forceVSAvoidnut structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent modifies the structural parameters of the nut by incorporating flexible fingers with specific geometric configurations and compression members with defined positioning features (such as circumferential grooves). These parameter changes enable the application of constant radial compressive force while maintaining a relatively simple overall structure that integrates smoothly with the lead screw mechanism

Inventive Principle:

Principle #35Parameter changes

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 design ensures constant engagement force with the lead screw, reducing stick slip and maintaining precise linear motion, even as the nut wears, by applying a radially inward compressive force directly to the flexible fingers, thus enhancing the functionality and accuracy of the lead screw assembly.

Implementation Method 1

The at least one radial compression member being installed proximate the at least one axial locator structure to apply a compressive force to the plurality of flexible fingers

Methodology Applied

Scientific EffectRadial compression force: Compression

Data Source

PatentEP2607749B1Nut with flexible fingers and radial compression members

Publication Date: 2017.02.22 PACIFIC BEARING

AI summary

A nut (110) and lead screw (104) assembly is disclosed. The nut (110) includes a plurality of flexible fingers (112) for adjusting the engagement of a threaded or unthreaded portion of the nut with corresponding threads (106) of a lead screw. The engagement between the nut (110) and the lead screw (104) is adjusted by installing at least one radial compression member (114) into a circumferential groove (116) formed in the outer surface of the flexible fingers (112).