Axially Guided Shaft Coupling for Backlash-Free Misalignment Compensation

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Solution Overview

Problem

Existing couplings for shafts often exhibit either excessive stiffness or excessive play, leading to imprecise actuation, particularly in high-movement equipment with lateral movements, failing to provide repeatable backlash-free operation.

Innovation Solution

A coupling design featuring a fixed coupling partner with retaining rings and a movable partner with axial adjustability via a guide, incorporating a sliding ring with bushing recesses for axial guidance and a compensating element like a bellows or spring assembly to eliminate play and ensure torsional rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a coupling is made stiff to reduce play, then positioning precision is improved, but adaptability to lateral movements and disruptions deteriorates

Engineering Contradiction:
Improvepositioning precisionVSAvoidadaptability to lateral movements
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The coupling employs a dynamic design where the movable coupling partner can shift axially and angularly relative to the fixed partner. The guide mechanism allows controlled movement along the longitudinal axis, while the compensating element (bellows or spring assembly) enables angular adjustment for deviation angles, allowing the coupling to adapt to lateral movements and disruptions while maintaining precise torque transmission.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a coupling allows movement freedom to handle disruptions, then adaptability is improved, but positioning precision and backlash-free operation deteriorates

Engineering Contradiction:
Improvemovement freedomVSAvoidbacklash-free operation
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The guide mechanism acts as an intermediary between the movable and fixed coupling partners, providing precise axial guidance that maintains positioning accuracy while allowing necessary movement. The compensating element serves as a mediator that absorbs angular deviations and lateral movements, ensuring that the torque transmission path remains precise and backlash-free despite the movement freedom provided.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If a coupling design is made compact, then device complexity is reduced, but the axial guide stroke capability deteriorates

Engineering Contradiction:
Improvecompact designVSAvoidaxial guide stroke
Core Design Contradiction:
Device complexityVSLength of moving object

Solution Approach 1:

The coupling design nests the movable coupling partner within the fixed coupling partner's structure. The movable partner is positioned inside the fixed partner's accommodating means, allowing the guide mechanism and compensating element to be integrated within the compact overall structure while still providing sufficient axial guide stroke for the application.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 enables backlash-free, torsionally rigid guidance with a long service life, precise operation, and compact design, while allowing for error compensation and reduced play both internally and externally.

Implementation Method 1

the movable coupling partner (5) being axially adjustable relative to the fixed coupling partner (2) by means of a guide (7) parallel to the central longitudinal axis (4) of the coupling

Methodology Applied
Scientific EffectMechanical guidance:

Implementation Method 2

the fixed coupling partner (2) having two fixed, spaced-apart retaining rings (8) with bolt connection means (9) arranged between them, with a movable sliding ring (10), which is assigned to the movable coupling partner (5), running on the bolt connection means (9) between the retaining rings (8)

Methodology Applied
Scientific EffectMechanical fastening: Mechanical Fastener

Implementation Method 3

the movable coupling partner (5) advantageously having a compensation element (12), for example in the form of a bellows element (15), which with regard to a deviation angle (13) relative to the central longitudinal axis (4) of the clutch

Methodology Applied
Scientific EffectAngular compensation:

Implementation Method 4

the compensating element (12) of the movable coupling partner (5) can have a bellows element (15), which is fastened with one end (16) in the displacement ring (10), in particular pressed and/or glued in on an inner side (17)

Methodology Applied
Scientific EffectBellows flexibility:

Implementation Method 5

the compensating element (12) of the movable coupling partner (5) is a spring assembly, which is fastened with one end in the displacement ring (10), in particular pressed and/or glued in on an inside (17)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3728886B1Coupling and method for use
Publication Date: 2021.11.17 KBK ANTRIEBSTECHN GMBH
  • EP3728886B1 patent drawingFigure 1a
  • EP3728886B1 patent drawingFigure 1b
  • EP3728886B1 patent drawingFigure 1c

AI summary

Coupling for receiving two shaft elements, comprising a fixed coupling partner with a receiving means for receiving the first shaft element with a coupling central longitudinal axis, and a coupling partner which can be moved in relation to the coupling central longitudinal axis with a receiving means for receiving the second shaft element, wherein the movable coupling partner can be adjusted, relative to the fixed coupling partner, axially parallel to the coupling central longitudinal axis by means of a guide, wherein the fixed coupling partner has two fixedly arranged, spaced apart holding rings with bolt connecting means which are arranged in between, wherein a movable displacement ring which is assigned to the movable coupling partner is provided between the holding rings so as to run on the bolt connecting means, with bushing cut-outs which correspond with the bolt connecting means and are configured with regard to their number, arrangement and geometry so as to correspond in such a way that they provide axial guidance.