Curved Shaft Coupling for Radial Misalignment Tolerance

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Solution Overview

Problem

Existing power transmission shaft couplings face significant loading issues due to radial errors between shafts, requiring precise alignment and increasing the risk of structural stress and reduced service life.

Innovation Solution

A shaft coupling design with a reduced number of bearings, utilizing a recess and protrusion with curved surfaces to accommodate radial errors, and a coupler to non-rotatably connect the shafts, allowing for greater tolerance in alignment without excessive loading on the coupling point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If four bearings are used to support the shafts, then the shafts are well supported, but radial errors cause major loading on the coupling point structures

Engineering Contradiction:
Improveshaft support stabilityVSAvoidcoupling point structural loading
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The protrusion and recess are given curved surfaces (specifically cylindrical or conical surfaces) instead of flat surfaces. This curvature allows the mating surfaces to accommodate radial misalignment between shafts, reducing the transmission of radial errors to the coupling point structures while maintaining reliable shaft support with only three bearings

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Strength

If precise alignment is required, then major loading on coupling point structures is avoided, but alignment complexity and installation difficulty increase

Engineering Contradiction:
Improvecoupling point structural loadingVSAvoidalignment requirement
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention changes the geometric parameters of the mating surfaces from flat to curved (cylindrical or conical). This parameter change transforms the coupling from one requiring precise alignment to one that tolerates radial errors, significantly easing installation and alignment operations while preventing excessive loading on coupling point structures

Inventive Principle:
Principle #35Parameter changes

3Reliability

If four bearings are used, then shaft support is adequate, but device complexity increases

Engineering Contradiction:
Improveshaft support stabilityVSAvoidnumber of bearings
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts (removes) one bearing from the conventional four-bearing configuration. By using curved mating surfaces between the protrusion and recess to accommodate radial misalignment, the design achieves adequate shaft support with only three bearings, reducing device complexity while maintaining reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3743633B1Shaft coupling
Publication Date: 2024.03.06 KONECRANES GLOBAL OY
  • EP3743633B1 patent drawingFigure 1
  • EP3743633B1 patent drawingFigure 2
  • EP3743633B1 patent drawingFigure 3

AI summary

The present invention relates to a shaft coupling which comprises a first shaft (1) supported by a bearing at a first end (1-1), and a second shaft (2) supported by a bearing at a second end (2-2). Said first shaft (1) and second shaft (2) are coaxially arranged so that the second end (1-2) of the first shaft (1) is against the first end (2-1) of the second shaft (2). On an end surface of the second end (1-2) of the first shaft (1), there is a recess (6), and a protrusion (7) protrudes from the end surface of the first end (2-1) of the second shaft (2), and said recess (6) receives said protrusion (7). The shaft coupling comprises only one third bearing (8), as well as a coupler (9) which receives the second end (1-2) of the first shaft (1) and the first end (2-1) of the second shaft (2). With such a solution, a greater radial error may be allowed between the shafts without the structures of the coupling point being overloaded.