Sprag Freewheel Cage Webs Replace Metallic Springs

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Solution Overview

Problem

Conventional sprag freewheels consist of multiple components, including a sprag cage and metallic springs, leading to complex production and high manufacturing costs.

Innovation Solution

A sprag freewheel design featuring an inner and outer ring with a sprag cage and axially distributed webs that act as resilient elements, eliminating the need for metallic springs by utilizing webs with higher elasticity than the clamping bodies, allowing for adjustable spring behavior and a compact, mechanically resistant structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metallic springs are used to hold sprags in position, then the sprags can be reliably positioned, but the structure becomes complex and manufacturing costs increase

Engineering Contradiction:
Improvesprag positioning reliabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the metallic springs from the sprag freewheel structure, extracting the separate spring component and replacing it with an integrated resilient web structure that is part of the sprag cage itself. This eliminates the need for separate spring elements while maintaining the spring-loading function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The resilient web structure combines the cage structure and spring function into a single integrated component. The webs form both the structural framework of the sprag cage and simultaneously provide the spring-loading action through their elastic deformation, merging two previously separate functions into one unified structure.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If multiple separate components (sprag cage, metallic springs) are used, then reliable spring-loading can be achieved, but production outlay and manufacturing complexity increase

Engineering Contradiction:
Improvespring-loading reliabilityVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The resilient webs integrate the cage structure and spring function into a single manufacturable component. The sprag cage can now be produced as one piece or fewer pieces through processes like injection molding or stamping, eliminating the need for separate spring manufacturing and assembly operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the material parameters of the cage structure by using materials with elastic properties (such as plastics or elastomers) instead of rigid metals. This allows the cage itself to exhibit spring-like behavior through elastic deformation, fundamentally changing how spring-loading is achieved from a mechanical component to a material property.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If conventional metallic springs are used, then the sprag freewheel can function reliably, but the number of components and assembly steps increase

Engineering Contradiction:
Improvefreewheel reliabilityVSAvoidassembly efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The resilient web structure merges the cage and spring functions, reducing the number of discrete parts that need to be assembled. The sprags are retained in the cage structure without requiring separate spring installation steps, streamlining the assembly process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cage is segmented into multiple resilient webs that independently provide spring-loading for each sprag. This segmentation allows each web to function autonomously while collectively providing the necessary spring-loading across all sprags, simplifying both structure and assembly.

Inventive Principle:
Principle #1Segmentation

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 simplifies the sprag freewheel structure, reduces manufacturing complexity, and allows for adjustable spring behavior, enhancing reliability and assembly ease while maintaining dimensional stability.

Implementation Method 1

The webs have a higher elasticity than the clamping body. Due to the higher elasticity of the webs of the clamping body cage compared to the clamping bodies, these act as resilient elements.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2660488B1Clamp body free wheel and clamp body cage for same
Publication Date: 2017.07.12 PAUL MULLER GMBH & CO KG UNTERNEHMENSBETEILIGUNGEN
  • EP2660488B1 patent drawingFigure 1~2
  • EP2660488B1 patent drawingFigure 3~4
  • EP2660488B1 patent drawingFigure 5

AI summary

The clutch (1) has an inner ring (2) which is arranged coaxially to outer ring (3). A gap is formed between inner ring and outer ring. The clamp portions (5a-5c) are set to form frictional connection with inner ring and outer ring in a clamping position. The clamping portion is arranged between extending bars (6). The extending bars having higher elasticity than clamping portion. The extending bars with elasticity higher than clamping portion is set. The extending bars is provided with a specific surface (7) which is contacted with clamping portion in freewheel position.