Centrifugal Coupling Integrating Spring Securing Element

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Solution Overview

Problem

Existing centrifugally actuated coupling devices face challenges in minimizing weight and size, particularly in hand-held tools, where the risk of spring breakage and subsequent damage to neighboring components is a concern, and require additional components for secure assembly which complicate the structure and increase weight.

Innovation Solution

A centrifugally actuated coupling device with a one-piece securing element integrated with the centrifugal weight, featuring wedge-shaped retaining lugs and radial securing elements, which secures the spring in place without increasing axial size, preventing lateral deflection and eliminating the need for separate securing components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate disk is used to cover the entire clutch for securing springs, then spring security is improved, but device complexity and weight increase

Engineering Contradiction:
Improvespring securityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The securing element is merged with the centrifugal weight to form a single integrated component. The securing element is formed as an extension of the centrifugal weight body, eliminating the need for separate securing disks or additional components. This integration maintains spring security while reducing device complexity and weight.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If a separate disk is used to cover the entire clutch for securing springs, then spring security is improved, but weight increases

Engineering Contradiction:
Improvespring securityVSAvoidclutch weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The securing element is merged with the centrifugal weight to form a single integrated component. The securing element is formed as an extension of the centrifugal weight body, eliminating the need for separate securing disks or additional components. This integration maintains spring security while reducing device complexity and weight.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If separate securing components are used, then assembly flexibility is improved, but assembly complexity increases

Engineering Contradiction:
Improveassembly flexibilityVSAvoidassembly complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The securing element is merged with the centrifugal weight to form a single integrated component. The securing element is formed as an extension of the centrifugal weight body, eliminating the need for separate securing disks or additional components. This integration maintains spring security while reducing device complexity and weight.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If the securing element is designed separately, then installation correction is possible, but incorrect installation risk increases

Engineering Contradiction:
Improveinstallation flexibilityVSAvoidinstallation correctness
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The securing element is merged with the centrifugal weight to form a single integrated component. The securing element is formed as an extension of the centrifugal weight body, eliminating the need for separate securing disks or additional components. This integration maintains spring security while reducing device complexity and weight.

Inventive Principle:
Principle #5Merging (Combining)

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 solution results in a lightweight, compact design with reduced overall weight and simplified assembly, effectively preventing spring fragments from escaping and ensuring secure positioning of centrifugal weights, thus enhancing safety and reducing the risk of damage to adjacent components.

Implementation Method 1

a centrifugal clutch (1), in which a holder (3) has guide sockets (4) for guiding centrifugal weights (5) in the radial direction, wherein the centrifugal weights (5) have friction surfaces (18) for frictional connection to a clutch drum (2)

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

adjacent centrifugal weights are connected to one another via tension coil springs (6)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2357375B1Centrifugal coupling device
Publication Date: 2015.07.29 ANDREAS STIHL AG & CO KG
  • EP2357375B1 patent drawingFigure 1~3
  • EP2357375B1 patent drawingFigure 4~7
  • EP2357375B1 patent drawingFigure 8~14

AI summary

A centrifugal coupling device has at least one centrifugal weight (5) mounted radially movable on a holder (3). The centrifugal weight (5) is movable between a radially inner and a radially outer position. The coupling device has at least one spring (6) that biases the centrifugal weight (5) towards the radially inner position. The coupling device has at least one locking element that secures at least one component of the coupling device in the direction of the axis of rotation (21) of the coupling device. A low weight and simple design of the coupling device are achieved if at least one locking element is formed integrally with the centrifugal weight (5).