Centrifugal Pump Rotor Bushing for Torque Transmission

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Solution Overview

Problem

Existing fastening methods for pump impellers require complex assemblies and significant material consumption, failing to achieve optimal power transmission and precise positioning efficiently.

Innovation Solution

A sheet metal impeller with a central coaxial opening and a bushing that projects outwards with axially parallel beads for secure fastening to the motor drive shaft, allowing for efficient force transmission and precise positioning with minimal material usage, using laser welding for attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional fastening methods are used for pump impellers, then the impeller can be securely mounted, but the assembly becomes complex and material consumption increases

Engineering Contradiction:
Improvesecure mountingVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The mounting bore is integrated directly into the impeller body, eliminating the need for separate mounting components. The impeller and mounting structure are merged into a single piece, achieving secure mounting while simplifying the assembly to just two parts (impeller and shaft).

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The mounting bore serves multiple functions simultaneously: it provides structural support for mounting the impeller to the shaft, enables precise axial positioning through the shoulder, and transmits torque through the keyed connection. This multi-functionality reduces the need for additional specialized components.

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

2Reliability

If conventional fastening methods are used for pump impellers, then the impeller can be securely mounted, but material consumption increases

Engineering Contradiction:
Improvesecure mountingVSAvoidmaterial consumption
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

By integrating the mounting bore directly into the impeller body, the design eliminates redundant mounting components and reduces overall material consumption. The single-piece construction achieves secure mounting with minimal material usage.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The design uses a simple, easily manufacturable mounting bore structure that can be produced with minimal material waste. The keyed connection and shoulder design allow for efficient material utilization without requiring excessive material for strength or positioning.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Device complexity

If a simple mounting design is used for the impeller, then assembly is easier, but torque transmission capability is reduced

Engineering Contradiction:
Improvemounting design simplicityVSAvoidtorque transmission
Core Design Contradiction:
Device complexityVSForce

Solution Approach 1:

The mounting bore incorporates a keyed connection with a keyway and key, creating a localized high-strength feature within the otherwise simple mounting structure. This local reinforcement enables high torque transmission while maintaining overall design simplicity and ease of assembly.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The mounting structure combines different geometric features (cylindrical bore, square keyway, axial shoulder) within a single integrated component, creating a composite structural solution that achieves both simplicity and high torque capacity through the synergistic combination of these features.

Inventive Principle:
Principle #40Composite materials

4Manufacturing precision

If precise impeller positioning is achieved, then power transmission is optimized, but the mounting structure becomes more complex

Engineering Contradiction:
Improveimpeller positioning precisionVSAvoidmounting structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The axial shoulder in the mounting bore is pre-formed as an integral feature during impeller manufacturing, establishing the precise axial position of the impeller on the shaft before assembly. This preliminary positioning feature eliminates the need for additional positioning components or complex adjustment mechanisms.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The positioning function is merged into the mounting bore structure itself through the integrated axial shoulder. This combination of positioning and mounting functions in a single feature achieves precise impeller positioning without adding structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

This solution enables simple and secure assembly with reduced material consumption, achieving optimal power transmission, precise positioning, and improved vibration behavior, particularly suitable for multi-stage pumps with low weight and high torque transmission.

Implementation Method 1

the bushing having axially parallel ridges in its inner wall for mounting in axially parallel notches or grooves of the motor drive shaft

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the bushing be welded into the central impeller opening, particularly by laser welding

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP2242928B1Fastening of the rotor of a centrifugal pump
Publication Date: 2018.03.07 WILO SE
  • EP2242928B1 patent drawingFigure 1~4
  • EP2242928B1 patent drawingFigure 5~6
  • EP2242928B1 patent drawingFigure 7

AI summary

The invention relates to a rotor, which is produced from sheet metal, of an in particular multi-stage centrifugal pump, having means for fastening to the drive shaft of an electric motor, wherein the rotor has a central coaxial opening in which a sleeve is fastened coaxially, wherein the sleeve projects out of the rotor at at least one side of the rotor, and wherein the sleeve has, in its inner wall, projecting, axially parallel beads for fastening in axially parallel notches or grooves of the motor drive shaft.