Wrap Spring Clutch Quick Release Mechanism

Solution Overview

Problem

Conventional wrap spring clutches face issues with undesirable drag and increased wear due to low differences in rotational speed during engagement and disengagement, making them unsuitable for certain applications, as they struggle to achieve a proper balance between engagement and disengagement.

Innovation Solution

A rotational coupling design that includes a wrap spring and shoes with springs to urge the wrap spring away from the output hub, facilitating quick release by providing a mechanism to bias the shoes radially outwardly, ensuring efficient disengagement even with low rotational speed differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the interference fit of the wrap spring is increased to improve engagement, then clutch engagement is improved, but disengagement becomes difficult and drag increases

Engineering Contradiction:

Improveclutch engagementVSAvoidclutch disengagement

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The clutch mechanism is segmented into distinct functional zones: the wrap spring engagement zone on the input hub, and the release zone with shoes and springs on the output hub. This segmentation allows the wrap spring to engage strongly during operation while the release mechanism provides a separate pathway for easy disengagement by urging the spring away from the output hub.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shoes and release springs act as intermediary elements between the wrap spring and the output hub. These intermediaries provide the necessary force to separate the wrap spring from the output hub during disengagement, resolving the contradiction between strong engagement and easy release.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the interference fit of the wrap spring is decreased to improve disengagement, then clutch disengagement is improved, but engagement becomes insufficient and drag increases

Engineering Contradiction:

Improveclutch disengagementVSAvoidclutch engagement

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The clutch mechanism is segmented into distinct functional zones: the wrap spring engagement zone on the input hub, and the release zone with shoes and springs on the output hub. This segmentation allows the wrap spring to engage strongly during operation while the release mechanism provides a separate pathway for easy disengagement by urging the spring away from the output hub.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shoes and release springs act as intermediary elements between the wrap spring and the output hub. These intermediaries provide the necessary force to separate the wrap spring from the output hub during disengagement, resolving the contradiction between strong engagement and easy release.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If conventional wrap spring clutch design is used in low rotational speed difference applications, then the clutch structure is simple, but undesirable drag and increased wear occur

Engineering Contradiction:

Improveclutch structureVSAvoiddrag and wear

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The shoes and release springs act as intermediary elements that actively manage the wrap spring's interaction with the output hub. By providing a controlled release mechanism, they minimize unnecessary contact and drag between the spring and hub surfaces, reducing wear and harmful effects in low-speed differential applications.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The release mechanism provides preliminary anti-action by pre-positioning the shoes and springs to counteract any tendency of the wrap spring to drag on the output hub during low-speed operation, preventing wear before it occurs.

Inventive Principle:

Principle #9Preliminary anti-action

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 design enables quick and complete release of the wrap spring, expanding the suitability of wrap spring clutches to applications previously unsuitable, by minimizing drag and wear, and improving clutch performance in low-speed differential scenarios.

Implementation Method 1

means, such as one or more springs, for biasing the shoes radially outwardly from the second hub

Methodology Applied

Scientific EffectSpring biasing: Spring

Data Source

PatentEP2609345B1Wrap spring clutch coupling with quick release feature

Publication Date: 2014.05.14 INERTIA DYNAMICS INC

Figure 1
Figure 2

AI summary

A rotational coupling is provided. The coupling includes first (12) and second (14) hubs disposed about an axis of rotation (24). The coupling further includes a wrap spring (16) engaging the first hub and disposed radially outwardly of the second hub. The wrap spring is configured to couple the first and second hubs together for rotation during rotation of the first hub in a first rotational direction. The coupling further includes means, disposed radially between the second hub and the wrap spring, for urging the wrap spring away from the second hub. The urging means may include one or more shoes (20) and means, such as springs (22), for biasing the shoes radially outwardly from the second hub. By urging the wrap spring away from the second hub, quick and complete release of the wrap spring occurs even where the difference in rotational speed between the hubs during clutch disengagement is low.