Agitator Impeller Blade Structure for Lower Drag and Welding Heat

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Solution Overview

Problem

Existing impellers for agitator systems are inefficient in terms of material usage, power consumption, and manufacturing complexity, with issues such as high drag, excessive material waste, and potential deformation during welding, leading to increased costs and operational inefficiencies.

Innovation Solution

The impeller design features a rotary hub with integrally formed inner blade sections of non-uniform thickness and outer blade sections of sheet metal, welded edge-to-edge, allowing for efficient force distribution, reduced drag, and simplified manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If impeller blades are made thick throughout their length to withstand forces near the hub, then the blades can cope with the forces closest to the hub, but this increases drag and power consumption as well as material usage

Engineering Contradiction:
Improveblade strengthVSAvoidpower consumption
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The blade thickness is varied along its length, being thickest near the hub where forces are greatest and gradually thinning toward the outer sections. This local variation in thickness provides the necessary strength where required while reducing drag and material usage in areas where less strength is needed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The blade is divided into multiple sections with different thicknesses, allowing each section to be optimized for its specific functional requirements. The inner section near the hub maintains greater thickness for strength, while outer sections are thinner to reduce drag.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If impeller blades are welded to the hub, then the blades can be attached to the hub, but the hub is subjected to high temperatures which risk deforming the hub

Engineering Contradiction:
Improveblade attachmentVSAvoidhub temperature
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

A hub extension is introduced as an intermediary component between the hub and the blade. The blade is welded to the hub extension rather than directly to the hub, which acts as a thermal buffer that protects the hub from excessive heat during the welding process.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The attachment structure is segmented into three parts: the hub, the hub extension, and the blade. This segmentation allows the welding process to be isolated to the hub extension-blade interface, protecting the main hub from thermal damage.

Inventive Principle:
Principle #1Segmentation

3Reliability

If the hub is deformed during welding, then the interface between the hub and blades must be machined to ensure balance, but this increases manufacturing time and cost

Engineering Contradiction:
Improveimpeller balanceVSAvoidmachining time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The hub extension is designed beforehand to compensate for potential thermal deformation. By providing this protective layer during welding, the main hub is shielded from deformation, eliminating or reducing the need for subsequent corrective machining operations.

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

4Ease of manufacture

If it is troublesome to reach the welding site with welding tools, then only some welding techniques are available, but this limits welding options

Engineering Contradiction:
Improvewelding accessibilityVSAvoidwelding technique options
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The hub extension serves as an intermediary that creates better accessibility to the welding zone. By positioning the welding interface at the end of the hub extension, welding tools can more easily reach the site, enabling the use of various welding techniques that would be difficult or impossible to apply directly to the hub.

Inventive Principle:
Principle #24Intermediary (Mediator)

5Manufacturing precision

If excessive amounts of welding material are used to enable postprocessing with desired results, then postprocessing can be performed, but excessive heat is generated which risks forming heat zones with reduced stress resistance

Engineering Contradiction:
Improvepostprocessing qualityVSAvoidwelding heat
Core Design Contradiction:
Manufacturing precisionVSTemperature

Solution Approach 1:

The hub extension acts as a sacrificial intermediary that absorbs excess heat during welding and postprocessing operations. This protective layer allows for the use of adequate welding material to achieve desired postprocessing quality without transferring excessive heat to the main hub, which would create vulnerable heat zones.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 design reduces material consumption, minimizes drag, and simplifies manufacturing steps while maintaining structural integrity and ease of assembly, resulting in a more cost-effective and efficient agitator system.

Implementation Method 1

The outer blade section is attached to the inner blade section by being welded edge-to-edge

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP4711031A1Impeller for an agitator system, agitator system and methods of forming an impeller for an agitator system
Publication Date: 2026.03.18 ALFA LAVAL CORP AB
  • EP4711031A1 patent drawingFigure 1
  • EP4711031A1 patent drawingFigure 2
  • EP4711031A1 patent drawingFigure 3

AI summary

The present invention relates to an impeller (100, 200) for an agitator system (10), comprising a rotary hub (102, 202) and two or more impeller blades (104, 204). Each impeller blade (104, 204) comprises an inner blade section (104a, 204a) of a non-uniform material thickness (T) connected to the rotary hub (102, 202) and an outer blade section (104b, 204b) of sheet metal. The outer blade section (104b, 204b) is attached to the inner blade section (104a, 204a) by being welded edge-to-edge. An agitator system (10) comprising an impeller (100, 200) and methods of forming an impeller (100, 200) for an agitator system (10) are also provided.