Linear Actuator with Continuous Cast Stator Cooling

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Solution Overview

Problem

Existing linear actuators are not cost-effective in producing a linear drive function and require complex post-processing for cooling medium passage, leading to increased energy consumption and heat development.

Innovation Solution

A linear actuator design featuring a stator and rotor with axially aligned magnets, a continuously cast profile with recesses for cooling medium passage, and a modular structure allowing for adaptable power, force, and travel length, using a helix angle between 0 and 30° to reduce pole detent and enable cost-effective production and efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If complex post-processing is used to create cooling medium passages, then cooling efficiency is improved, but manufacturing cost and complexity increase

Engineering Contradiction:
Improvecooling efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling passages are pre-formed during the continuous casting process of the extruded profile, rather than requiring post-processing. The mold used in continuous casting already includes the cooling passage geometry, so the passages are created in advance as the profile is being formed, eliminating the need for subsequent machining or drilling operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The cooling passage creation process is merged with the continuous casting process. Both the structural profile and the cooling passages are formed simultaneously in a single manufacturing step, combining what would traditionally be separate operations into one integrated process.

Inventive Principle:
Principle #5Merging (Combining)

2Temperature

If more cooling passages are added, then heat dissipation is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveheat dissipationVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

Multiple cooling passages are pre-formed during the continuous casting process, allowing heat dissipation requirements to be met without adding post-processing complexity. The mold design accommodates multiple passages from the start.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If magnets are arranged with offset in circumferential direction, then pole detent is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvepole detent reductionVSAvoidmagnet assembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The magnet arrangement is segmented into multiple individual magnet pieces rather than a single continuous magnet. This segmentation allows each magnet to be positioned with a specific offset in the circumferential direction, reducing pole detent while maintaining manufacturing feasibility through modular assembly.

Inventive Principle:
Principle #1Segmentation

4Reliability

If helix angle is increased, then pole detent reduction is improved, but magnetic field alignment may be compromised

Engineering Contradiction:
Improvepole detent reductionVSAvoidmagnetic field alignment
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The helix angle is optimized to a specific range (0-30 degrees) to achieve the right balance between pole detent reduction and magnetic field alignment. This parameter optimization ensures that the magnets are tilted enough to reduce pole detent while maintaining sufficient axial alignment for effective magnetic field generation.

Inventive Principle:
Principle #35Parameter changes

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 cost-effective production of linear actuators with reduced energy consumption and heat development, allowing for adaptable power and force generation, and efficient cooling medium passage without the need for post-processing, while maintaining high force capabilities.

Implementation Method 1

each module comprising a winding applied to a coil body, with which an essentially axially directed magnetic field can essentially be generated

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the stator comprising an extruded profile which has recesses for the passage of cooling medium

Methodology Applied
Scientific EffectThermal convection: Convection

Implementation Method 3

the runner including magnets whose direction of magnetization is aligned essentially in the axial direction

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP2122812B1Linear actuator
Publication Date: 2019.04.10 SEW EURODRIVE GMBH & CO KG
  • EP2122812B1 patent drawingFigure 1
  • EP2122812B1 patent drawingFigure 2
  • EP2122812B1 patent drawingFigure 3

AI summary

Comprising a stator and a rotor, wherein the rotor comprises magnets whose direction of magnetization is substantially aligned in the axial direction, a skew angle being provided, wherein the stator comprises at least one module, with each module comprising a winding applied on a coil former, with which winding substantially an axially aligned magnetic field can be produced, in particular in the region of the magnets, wherein the stator comprises a continuous casting profile, which comprises cutouts for passing through cooling medium, wherein the outer surface of the continuous casting profile is formed together with the coil former in such a way that axially extending cavities are formed, in particular for passing through lines, wherein the coil former is manufactured from steel and has depressions 41 running in the circumferential direction, into which depressions the stator winding wires and/or the respective parts of the windings are inserted.