Screw Vacuum Pump Rotor Thermal Management

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Solution Overview

Problem

Compact screw vacuum pumps face challenges with high heat release and thermal management, especially in the area of compression on the atmosphere side, and are not suitable for use with chemically aggressive substances due to material limitations and heat dissipation issues.

Innovation Solution

The design incorporates a rotor with a highly thermally conductive core material, such as aluminum or copper, surrounded by a chemically resistant plastic sleeve, where the core extends into the screw threads for effective heat dissipation, and a hollow shaft for internal cooling, reducing thermal expansion and material costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional materials (steel or cast iron) are used for rotors, then structural strength and rigidity are ensured, but heat dissipation is insufficient and chemical resistance is poor

Engineering Contradiction:
Improveheat dissipationVSAvoidchemical resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The rotor is constructed as a composite structure with a metal core (aluminum or copper) providing thermal conductivity, surrounded by a plastic coating (polymer, fluoropolymer, or elastomer) providing chemical resistance. This composite design allows the rotor to simultaneously achieve effective heat dissipation through the metal core and resistance to chemically aggressive substances through the protective plastic coating, resolving the contradiction between heat dissipation and chemical resistance.

Inventive Principle:
Principle #40Composite materials

2Temperature

If high thermal conductivity materials (aluminum or copper) are used for the rotor core, then heat dissipation is improved, but chemical resistance deteriorates

Engineering Contradiction:
Improvethermal conductivityVSAvoidchemical aggression
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The rotor uses a metal core made of aluminum or copper which provides high thermal conductivity for effective heat dissipation, while the surrounding plastic coating (polymer, fluoropolymer, or elastomer) provides protection against chemically aggressive substances. This composite structure allows each material to perform its optimal function without compromising the other.

Inventive Principle:
Principle #40Composite materials

3Object-affected harmful factors

If plastic material is used for the rotor, then chemical resistance is improved, but heat dissipation capability deteriorates

Engineering Contradiction:
Improvechemical resistanceVSAvoidheat dissipation
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The rotor design combines a metal core (aluminum or copper) with high thermal conductivity for effective heat dissipation, surrounded by a plastic coating that provides chemical resistance. The metal core handles the thermal management while the plastic coating protects against chemical aggression, allowing the rotor to overcome the limitations of pure plastic material.

Inventive Principle:
Principle #40Composite materials

4Power

If internal compression is increased to reduce heat release, then power requirement is reduced, but internal overpressure occurs causing motor overload

Engineering Contradiction:
Improvepower requirementVSAvoidinternal overpressure
Core Design Contradiction:
PowerVSStress or pressure

Solution Approach 1:

The patent modifies the screw geometry parameters, specifically the screw pitch and/or screw radius, to create internal compression in the range of 2-10. This parameter change reduces the power requirement and heat release by almost the compression factor, while the improved heat dissipation capability of the new rotor design prevents internal overpressure from causing motor overload.

Inventive Principle:
Principle #35Parameter changes

5Volume of moving object

If rotor mass is reduced for compact design, then pump size is reduced, but heat dissipation capability deteriorates

Engineering Contradiction:
Improvepump sizeVSAvoidheat dissipation
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The rotor uses a metal core (aluminum or copper) which has high thermal conductivity and can be made with lower mass compared to traditional steel rotors. The plastic coating adds minimal mass while providing chemical resistance. This composite structure allows the rotor to maintain compact dimensions with reduced mass while preserving effective heat dissipation through the metal core.

Inventive Principle:
Principle #40Composite materials

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 configuration enables effective cooling of the rotor, reduces thermal expansion, and provides a chemically resistant and lightweight rotor with improved heat dissipation, addressing the issues of high heat release and material limitations, while maintaining structural integrity and reducing production costs.

Implementation Method 1

The rotor (1) consists of a highly thermally conductive core material... enables effective cooling of the rotor, reduces thermal expansion... with improved heat dissipation

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a hollow shaft for internal cooling... The design incorporates a rotor with a highly thermally conductive core material... surrounded by a chemically resistant plastic sleeve

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP2615307B1Screw vacuum pump
Publication Date: 2019.08.21 VACUUBRAND
  • EP2615307B1 patent drawingFigure 1
  • EP2615307B1 patent drawingFigure 2

AI summary

The rotor (1) has a rotor core (3) arranged and fitted on a rotor shaft (2), where the rotor shaft is made of copper or aluminum alloys. The rotor core partially surrounds a rotor casing (4), and is made of material with heat conductivity greater than 200 W/mK. The rotor shaft and the rotor core are integrally formed. The rotor shell is applied on the rotor core using an injection molding process, and reinforces with a filler such as glass fibers, carbon fibers or plastic material. An independent claim is also included for a screw vacuum pump.