Scroll Pump Synchronous Motor Axial Force Seal Compression

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Solution Overview

Problem

Scroll vacuum pumps using asynchronous electric motors suffer from low efficiency and high temperature issues, which can lead to reduced service life of sealing materials and increased energy consumption.

Innovation Solution

A scroll pump design utilizing a synchronous motor with a rotor offset to generate an axial force, improving seal compression and efficiency, combined with a controller to regulate rotor speed based on pressure and temperature for energy savings and extended seal life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If an asynchronous electric motor is used to drive the scroll pump, then the pump can operate, but the efficiency is low and high temperatures are generated

Engineering Contradiction:
Improvemotor efficiencyVSAvoidmotor temperature
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The patent changes the operating parameters of the electric motor by offsetting the rotor axially relative to the stator. This parameter change transforms the motor from an asynchronous motor with poor efficiency into a synchronous motor configuration, thereby improving energy efficiency and reducing temperature generation while maintaining the required driving function.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the rotor is offset to generate axial force, then seal compression is improved, but the motor structure becomes more complex

Engineering Contradiction:
Improveseal compressionVSAvoidmotor structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The axial offset of the rotor serves multiple functions simultaneously: it generates the necessary axial force to compress the seals (improving reliability) and transforms the motor into a synchronous configuration (improving efficiency). This multi-functionality approach avoids the need for separate sealing mechanisms, thereby limiting the increase in structural complexity.

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

3Use of energy by moving object

If rotor speed is varied to save energy, then energy consumption is reduced, but control complexity increases

Engineering Contradiction:
Improveenergy consumptionVSAvoidcontrol system
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent implements dynamic speed control of the rotor based on the pumping phase. During the pumping phase, the rotor operates at higher speed to maintain suction capacity, while during the maintenance phase, the speed is reduced to save energy. This dynamic adaptation allows energy optimization with relatively simple control logic that responds to operational conditions.

Inventive Principle:
Principle #15Dynamics

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 synchronous motor design reduces heat generation and extends seal life, allows for adjustable suction capacity, and achieves energy savings by varying rotor speed, particularly during the maintenance phase of the pumping process.

Implementation Method 1

the rotor of the electric motor is arranged relative to the stator of the electric motor such that during operation of the electric motor a force directed in an axial direction is generated on the rotor

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

Seen in the axial direction, at least one seal can be arranged between the movable part of the scroll pump stage and a stationary part of the scroll pump stage, which seal is compressed or pressed by the axial force between the movable and the stationary part of the scroll pump stage

Methodology Applied
Scientific EffectAxial force compression: Mechanical Force

Data Source

PatentEP3508727B1Scroll pump and method for operating a scroll pump
Publication Date: 2020.05.13 PFEIFFER VACUUM GMBH
  • EP3508727B1 patent drawingFigure 1~4
  • EP3508727B1 patent drawingFigure 2A~2B
  • EP3508727B1 patent drawingFigure 3

AI summary

A scroll pump, in particular a scroll vacuum pump, comprises at least one scroll pump stage for conveying a gas from a gas inlet through the scroll pump stage to a gas outlet and an electric motor having a stator and a rotor, wherein the rotor is coupled to the moving part of the scroll pump stage for driving a moving part of the scroll pump stage.