Additive Shaft-Hub Locking Connection for Tool-Free Axial Joining

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Solution Overview

Problem

Existing shaft-hub connections in applications like centrifugal pumps require additional fastening means and metal inserts, which are cumbersome, costly, and can lead to component fractures due to the brittle nature of plastic materials under mechanical stress, especially during assembly and disassembly.

Innovation Solution

A fastening component with an integrated, additively manufactured locking mechanism featuring a pivoting lever that engages with a counter-component, eliminating the need for external fasteners and metal inserts, allowing for tool-free assembly and disassembly while ensuring secure connection and force transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional fastening means (screws, nuts, retaining rings) are used to secure the hub in the axial direction, then the connection reliability is improved, but the device complexity and assembly time increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the hub and the locking mechanism into a single integrated component. The hub features integrated locking elements (such as axial locking protrusions or radial locking levers) that are formed as one piece with the hub body, eliminating the need for separate fastening means like screws, nuts, or retaining rings. This merging of functions reduces device complexity while maintaining connection reliability through the integrated positive locking features.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If additional fastening means are used to secure the hub, then the connection reliability is improved, but the assembly time and production cost increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The hub and locking mechanism are merged into a single integrated component with locking elements formed directly on the hub body. This eliminates multiple assembly steps involving separate fasteners, allowing the shaft-hub connection to be assembled quickly by simply inserting the shaft into the hub where the integrated locking elements automatically engage with corresponding features on the shaft.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If metal inserts are used to form the impeller hub for press connection with a metal shaft, then the connection strength is improved, but the manufacturing cost and complexity increase

Engineering Contradiction:
Improveconnection strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent employs composite material construction where a plastic hub (which can be additively manufactured) incorporates integrated locking features that engage with a metal shaft. The plastic hub material is selected to provide sufficient strength and wear resistance for the application, eliminating the need for metal inserts while maintaining adequate connection strength through the integrated positive locking mechanism.

Inventive Principle:
Principle #40Composite materials

4Weight of moving object

If the hub is made of plastic material with thin walls, then the weight and manufacturing complexity are reduced, but the component strength and reliability decrease due to brittleness under mechanical stress

Engineering Contradiction:
Improvehub weightVSAvoidcomponent strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The hub is pre-assembled onto the shaft with the integrated locking elements already in position to engage with the shaft features. This preliminary positioning ensures that when the shaft is inserted, the locking elements immediately engage to prevent axial displacement, distributing mechanical stresses evenly and preventing the thin-walled plastic hub from experiencing concentrated loads that would cause fracture.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The locking mechanism incorporates movable elements (such as spring-loaded locking levers or flexible locking protrusions) that can dynamically adjust to accommodate manufacturing tolerances and distribute mechanical loads. This dynamic capability allows the thin-walled plastic hub to withstand mechanical stresses without fracturing, as the locking elements can deform slightly to absorb stress peaks.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3812604B1Positive connection between two components, especially a shaft-hub connection
Publication Date: 2021.12.01 WILO SE
  • EP3812604B1 patent drawingFigure 1~3
  • EP3812604B1 patent drawingFigure 4~5
  • EP3812604B1 patent drawingFigure 6

AI summary

The invention relates to a fastening component (1, 35) for positive locking connection with a counter-component (2, 36) by axial joining, characterized by a housing part (5) with at least one open chamber (6) in which at least one lever (3, 4) is located, which can be pivoted into a locking position with the counter-component (2, 36), wherein the housing part (5) and the lever (3, 4) are manufactured in a simultaneous manufacturing step by an additive process.