Pronged Sleeve Flexible Shaft Coupling Torque Capacity

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Solution Overview

Problem

Existing flexible sleeve couplings face issues with shear failure under torsional load, centrifugal expansion, and limited durability, while fail-safe designs often compromise on flexibility and vibration isolation.

Innovation Solution

A flexible shaft coupling with a reinforced elastomeric sleeve featuring a dual-tooth profile, where groove teeth and gap teeth of different sizes mesh with prong grooves and gaps, providing both tension and compression sections for enhanced durability and torque capacity in a compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the elastomeric sleeve is reinforced with fibers, composites or higher strength plastics to improve tooth shear resistance, then the sleeve becomes relatively thick and bulky

Engineering Contradiction:
Improvetooth shear resistanceVSAvoidsleeve thickness
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The sleeve is segmented into two distinct tooth profiles: groove teeth that engage with prong grooves and gap teeth that engage with spaces between prongs. This segmentation allows each tooth type to be optimized for its specific function, with groove teeth designed for tension loads and gap teeth for compression loads, thereby improving overall tooth shear resistance without requiring uniform thickening of the entire sleeve.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the sleeve are given different properties through the dual-tooth profile design. The groove teeth are positioned and sized to handle tension loads from driver prongs, while gap teeth are positioned to handle compression loads from driven prongs. This local differentiation of functional properties allows the sleeve to achieve high strength where needed without unnecessary material elsewhere, reducing overall sleeve bulk.

Inventive Principle:
Principle #3Local quality

2Reliability

If the sleeve is reinforced with tensile cords or provided with annular cavities to protect from centrifugal forces, then the device complexity increases

Engineering Contradiction:
Improveresistance to centrifugal expansionVSAvoidsleeve structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The dual-tooth profile design merges the functions of load transmission and centrifugal force resistance into a single integrated structure. The groove teeth and gap teeth work together not only to transmit torque but also to provide structural reinforcement against centrifugal expansion, eliminating the need for separate reinforcement elements like tensile cords or annular cavities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The dual-tooth profile structure serves multiple functions simultaneously: it transmits torque through meshing with prongs, resists centrifugal expansion through its reinforced geometry, and provides fail-safe operation. This multi-functionality reduces device complexity by eliminating the need for separate components dedicated to each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If hubs are provided with radially overlapping teeth or prongs to prevent sleeve twisting and shearing, then the coupling size increases

Engineering Contradiction:
Improveresistance to twisting and shearingVSAvoidcoupling size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

Instead of having the prongs overlap radially to prevent sleeve failure, this invention inverts the approach by having the sleeve teeth (groove and gap teeth) actively engage with and interlock with the prong grooves and spaces. This reversal of the engagement mechanism allows the sleeve itself to provide the anti-twisting and anti-shearing protection, eliminating the need for oversized overlapping prongs.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The coupling system functions as a composite structure where the rigid metal prongs with grooves work in conjunction with the flexible elastomeric sleeve featuring dual-tooth profiles. This composite arrangement allows the combination of materials to provide torsional rigidity and failure protection without requiring increased coupling size, as each material contributes its advantageous properties to the overall system.

Inventive Principle:
Principle #40Composite materials

4Reliability

If a thin elastomer layer is used in fail-safe compression-type designs, then flexibility and vibration isolation are compromised

Engineering Contradiction:
Improvefail-safe operationVSAvoidflexibility and vibration isolation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The elastomeric sleeve is designed to be dynamic in its response to different types of loads. The dual-tooth profile allows the sleeve to flex and deform elastically under normal operating conditions, providing vibration isolation and flexibility. However, under excessive torque conditions, the interlocking groove teeth and gap teeth engage more rigidly with the prongs, providing fail-safe protection. This dynamic behavior allows the same component to provide both flexibility and fail-safe operation.

Inventive Principle:
Principle #15Dynamics

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 coupling achieves excellent torsional load capacity, fail-safe operation, and vibration damping in a compact package, with increased durability and torque rating while minimizing material usage.

Implementation Method 1

The sleeve has a plurality of inner teeth including a plurality of groove teeth and a plurality of gap teeth. The prong grooves and groove teeth mesh, and the gap grooves and gap teeth mesh.

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

A flexible shaft coupling with a reinforced elastomeric sleeve featuring a dual-tooth profile

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

The coupling achieves excellent torsional load capacity, fail-safe operation, and vibration damping in a compact package

Methodology Applied
Scientific EffectVibration: Vibration

Implementation Method 4

vibration damping

Methodology Applied
Scientific EffectDamping: Damping

Data Source

PatentEP2623811B1Pronged sleeve-type flexible shaft coupling
Publication Date: 2019.07.03 THE GATES CORP
  • EP2623811B1 patent drawingFigure 1~2
  • EP2623811B1 patent drawingFigure 3~4
  • EP2623811B1 patent drawingFigure 5~6

AI summary

A shaft coupling with a flexible annular sleeve, a driver end piece, and a driven end piece. The end pieces have a plurality of axially projecting prongs arranged so that the driver prongs loosely interlock in the spaces between the driven prongs with a gap between each pair of prongs. The sleeve fits snugly around the periphery of the loosely interlocked prongs. Each prong has at least one prong groove in its outer periphery. Each of two peripheral edges may be shaped to form a groove flank, and each set of two adjacent groove flanks on adjacent prongs may form a gap groove. The sleeve has a plurality of inner teeth including a plurality of groove teeth in alternating arrangement with a plurality of gap teeth. The prong grooves and groove teeth mesh, and the gap grooves and gap teeth mesh. Groove teeth may be bigger than gap teeth.