Turbomolecular Pump Magnetic Field Sensor Control

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Solution Overview

Problem

Vacuum pumps, particularly turbomolecular pumps, face operational risks due to external magnetic fields that induce eddy currents, leading to rotor heating and potential failure, necessitating restrictive magnetic field limits and complex measurements, which are unsuitable for variable magnetic field environments.

Innovation Solution

Equipping vacuum pumps with a magnetic field sensor and a control/evaluation unit that continuously monitors the magnetic field, allowing for condition-dependent measures such as slowing or stopping the rotor, activating cooling devices, or switching off the pump to maintain safe operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the vacuum pump is equipped with a magnetic field sensor and control unit to detect and respond to external magnetic fields, then the reliability of operation in high magnetic field environments is improved, but the device complexity increases

Engineering Contradiction:
Improvesafe operation in magnetic fieldVSAvoidsensor and control unit
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where a magnetic field sensor continuously monitors the external magnetic field strength, and a control unit adjusts the rotor speed based on the detected field strength. When the magnetic field exceeds a predetermined threshold, the control unit reduces the rotor speed to prevent eddy current heating, thereby maintaining safe operation while adapting to changing magnetic field conditions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The vacuum pump performs self-protection by automatically detecting harmful magnetic fields and adjusting its own operation without external intervention. The control unit monitors the magnetic field environment and autonomously modifies the rotor speed to prevent damage from eddy currents, enabling the system to safeguard itself in variable magnetic field conditions.

Inventive Principle:
Principle #25Self-service

2Reliability

If complex magnetic field measurements are performed before startup to define operating limits, then the reliability is improved, but the loss of time and ease of operation deteriorate

Engineering Contradiction:
Improvesafe operation limit definitionVSAvoidmeasurement time before startup
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent incorporates a magnetic field sensor and control unit that are pre-installed and configured in the vacuum pump before deployment. The control unit contains predetermined threshold values for magnetic field strength, eliminating the need for complex on-site measurements before startup. The system is ready to automatically detect and respond to magnetic field conditions immediately upon operation.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the rotor speed is reduced or stopped to prevent eddy current heating in strong magnetic fields, then the reliability is improved, but the productivity decreases

Engineering Contradiction:
Improveprevention of rotor heatingVSAvoidpump operation speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements dynamic speed control where the rotor speed is continuously adjusted based on the detected magnetic field strength. In low magnetic field environments, the rotor operates at full speed for maximum productivity. When the magnetic field strength exceeds the predetermined threshold, the control unit dynamically reduces the rotor speed to prevent eddy current heating, thereby optimizing the balance between reliability and productivity according to environmental 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

Enables safe operation of vacuum pumps in high and time-varying magnetic fields by dynamically adjusting the pump's operation, preventing damage and ensuring continuous functionality.

Implementation Method 1

a sensor for detecting a magnetic field is provided, which is connected to a control and/or evaluation unit

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

The magnetic field can induce eddy currents in the spinning rotor, causing the rotor to heat up

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

The magnetic field can induce eddy currents in the spinning rotor, causing the rotor to heat up

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 4

The thermal expansion of the rotor can reduce the distance between the rotor and the stationary components of the vacuum pump surrounding the rotor

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3926174B1Vacuum pump
Publication Date: 2023.06.14 PFEIFFER VACUUM TECH AG
  • EP3926174B1 patent drawingFigure 1
  • EP3926174B1 patent drawingFigure 2
  • EP3926174B1 patent drawingFigure 3

AI summary

The invention relates to a vacuum pump, in particular a turbomolecular pump, with a rotor rotatable about a rotational axis, wherein a sensor for detecting a magnetic field is provided which is connected to a control and/or evaluation unit, wherein the control and/or evaluation unit is configured to evaluate the detected magnetic field and to take action on the basis of the evaluation depending on at least one condition.