Screw Vacuum Pump Direct Drive Motor Active Liquid Cooling

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Solution Overview

Problem

The technical vacuum performance of screw vacuum pumps is affected by temperature-induced changes in component shape, leading to inefficiencies and heat generation, particularly due to gaps between screw rotors and the housing, which impact power consumption and heat dissipation.

Innovation Solution

The implementation of a direct drive motor system with active liquid cooling for both screw rotors and the motor, along with a non-contact seal and optimized screw rotor design, reduces mechanical losses and heat production, while strategic heat management through cooling systems and insulation enhances efficiency and temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If traditional coupling and transmission systems are used to drive screw rotors, then mechanical flexibility and speed control are achieved, but mechanical losses and heat generation increase

Engineering Contradiction:
Improvemechanical lossesVSAvoidcoupling and transmission system
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The motor and screw rotor are merged into a single integrated unit, with the motor rotor directly forming the screw rotor. This eliminates the need for separate coupling and transmission components, reducing mechanical losses and heat generation while maintaining driving functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Traditional mechanical coupling and transmission systems are replaced with a direct electromagnetic drive system. The motor generates rotational force directly on the screw rotor through electromagnetic fields, eliminating mechanical intermediaries that cause energy losses.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If passive cooling is used for heat dissipation, then system simplicity is maintained, but temperature control and vacuum performance are insufficient

Engineering Contradiction:
Improvetemperature controlVSAvoidcooling system
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

A liquid cooling system is implemented using hydraulic principles, with cooling channels circulating coolant through the housing and motor components. This active liquid cooling system effectively dissipates heat from critical areas, maintaining optimal temperatures for vacuum performance.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Reliability

If gaps between screw rotors and housing are reduced to improve vacuum performance, then sealing improves, but heat accumulation increases due to reduced cooling surface area

Engineering Contradiction:
Improvevacuum performanceVSAvoidheat accumulation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The housing is divided into multiple sections with integrated cooling channels distributed throughout. This segmentation allows cooling surfaces to be positioned close to heat-generating components without compromising the overall sealing and vacuum performance of the pump.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Cooling channels are implemented in three-dimensional space within the housing structure, utilizing vertical and radial dimensions. This allows extensive cooling surface area to be achieved without increasing the horizontal gap dimensions that would compromise vacuum sealing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Volume of stationary object

If high power density is used to reduce pump size, then compactness is achieved, but heat generation increases requiring effective heat dissipation

Engineering Contradiction:
Improvepump sizeVSAvoidheat generation
Core Design Contradiction:
Volume of stationary objectVSTemperature

Solution Approach 1:

The motor is nested within the housing structure with cooling channels integrated into the motor stator and rotor assemblies. This nested arrangement allows high power density in a compact volume while maintaining effective heat dissipation pathways through the integrated cooling system.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 approach improves the energy efficiency and vacuum performance of screw vacuum pumps by minimizing temperature fluctuations, reducing mechanical losses, and effectively dissipating heat, resulting in a more reliable and cost-effective pumping system.

Implementation Method 1

Active liquid cooling can be provided both for the screw rotors and for the motor. This limits the temperatures both in the area of the motor and in the area of the screw rotors

Methodology Applied
Scientific EffectLiquid cooling: Convection

Implementation Method 2

The active cooling ensures rapid heat dissipation and thus helps to limit the temperatures in the screw pump

Methodology Applied
Scientific EffectHeat dissipation: Conduction (thermal)

Implementation Method 3

A motor can be provided which is designed as a direct drive for one of the screw rotors. Since the motor is designed as a direct drive, there is no need to provide a clutch between the motor and the relevant screw rotor

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 4

two screw rotors which are arranged in the housing and engage with one another and which, in order to transport a process gas, repeatedly form closed transport volumes of the process gas in cooperation with the housing and transport them in the direction of an outlet

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3499039B1Screw vacuum pump
Publication Date: 2021.03.31 PFEIFFER VACUUM GMBH
  • EP3499039B1 patent drawingFigure 1
  • EP3499039B1 patent drawingFigure 2
  • EP3499039B1 patent drawingFigure 3

AI summary

Screw vacuum pump with a housing (16), two screw rotors (28, 30) arranged in the housing and meshing with each other, which in conjunction with the housing (16) repeatedly form closed delivery volumes of the process gas and convey it towards an outlet (24), and a motor (12) which is designed as a direct drive for one of the screw rotors (28, 30), wherein active liquid cooling is provided for both the screw rotors (28, 30) and the motor (12).