Flexible Shaft Coupling Hub Flange Overload Protection

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Solution Overview

Problem

Existing flexible shaft couplings face issues with disk pack breakage due to high-frequency flexural stresses at high speeds, leading to manufacturing costs being higher than necessary for oversized designs to ensure security against breakage.

Innovation Solution

The design incorporates wing-like hub flanges that protrude radially and are received in recesses of the connecting flange with planar stop surfaces, providing a large contact area to distribute torque and prevent material wear, with the stop surfaces lying in planes intersecting the shaft axis, thus avoiding punctiform pressure and allowing perpendicular force transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the disk pack is oversized to achieve high security against disk breakage, then the reliability is improved, but the manufacturing costs increase

Engineering Contradiction:
Improvesecurity against disk breakageVSAvoidmanufacturing costs
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent implements overload protection elements (hub flange and connecting flange) that are designed to engage before the disk pack fails under excessive loads. These elements provide a mechanical stop that limits the maximum torque transmitted to the disk pack, preventing breakage without requiring an oversized design. The cushioning effect is achieved through the controlled engagement of the form-fitting elements at predetermined load thresholds.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the structural parameters of the coupling by introducing wing-like hub flanges with planar stop surfaces that engage with corresponding surfaces on the connecting flange. This geometric modification creates a mechanical limit to torque transmission, allowing the disk pack to be sized for normal operating conditions rather than extreme overload conditions, thereby reducing manufacturing costs while maintaining reliability.

Inventive Principle:
Principle #35Parameter changes

2Power

If the disk pack is subjected to high-frequency flexural stresses at high speeds, then the power transmission capability is improved, but the risk of lamella breakage increases

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoiddisk pack integrity
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The overload protection elements engage before the disk pack reaches stress levels that could cause lamella breakage. The planar stop surfaces create a mechanical barrier that prevents excessive torque from being transmitted to the disk pack during high-speed operation, cushioning the system against sudden load spikes and high-frequency stresses that would otherwise lead to fatigue failure.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent converts the potential harmful effect of high-frequency flexural stresses into a beneficial protective mechanism. The overload protection elements are designed to engage under extreme conditions, transforming what would be destructive stress cycles into controlled mechanical engagement events that protect the disk pack while still allowing normal power transmission at high speeds.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Stress or pressure

If the contact surface area between hub flange and connecting flange is increased, then the surface pressure is reduced, but the structural complexity increases

Engineering Contradiction:
Improvesurface pressureVSAvoidstructural complexity
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

The patent segments the torque transmission function into two distinct mechanisms: the disk pack for normal operation and the overload protection elements (hub flange and connecting flange) for extreme conditions. The planar stop surfaces on the hub flange create a distributed contact area that engages only when needed, reducing surface pressure without requiring continuous structural complexity. The segmented design allows simple geometry that engages only under specific load conditions.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2019222B1Flexible shaft coupling with disk pack and form-fitting elements
Publication Date: 2011.02.23 SIEMENS AG
  • EP2019222B1 patent drawingFigure 1
  • EP2019222B1 patent drawingFigure 2
  • EP2019222B1 patent drawingFigure 3

AI summary

The coupling has a hub (1'') with a tubular-shaped section for receiving a shaft. The hub has multiple wing-like hub flanges (1.1'), which are connected individually with the tubular-shaped section, and stick out radially to outer side. A mounting flange (3.1') has recesses (3.4'), where the hub flanges with a clearance (S) are accommodated in the recesses in a form-fit manner. Edges of the hub flanges face each other, where the edges and the recesses comprise planar stopping surface (6), which defines a contact area and lies in a plane that intersects the shaft carrying the hub.