Magnetic levitation vacuum pump

Patent metadata

Field	Value
Publication number	US-10634147-B2
Application number	US-201715408531-A
Country	US
Kind code	B2
Filing date	Jan 18, 2017
Priority date	Mar 18, 2016
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A magnetic bearing vacuum pump comprises: a first displacement signal generation section configured to amplify, by a resolution multiplying factor K of K>1, a displacement modulated wave signal modulated according to a displacement of the rotor from a predetermined position to generate a high-resolution displacement signal in a first displacement region including the predetermined position; a second displacement signal generation section configured to generate a low-resolution displacement signal in a larger second displacement region including the first displacement region; a selection section configured to select either one of the high-resolution displacement signal or the low-resolution displacement signal based on an unsteady-state response signal obtained by excluding a steady-state whirling displacement component from the high-resolution displacement signal or the low-resolution displacement signal; and a bearing control section configured to control the magnetic bearing based on the displacement signal selected by the selection section.

First claim

What is claimed is:

1. A magnetic bearing vacuum pump comprising:
a magnetic bearing configured to magnetically levitate a rotor;
a first displacement signal generation section configured to amplify, by a resolution multiplying factor K of K>1, a displacement modulated wave signal modulated according to a displacement of the rotor from a predetermined position to generate a high-resolution displacement signal in a first displacement region including the predetermined position based on the amplified displacement modulated wave signal;
a second displacement signal generation section configured to generate a low-resolution displacement signal in a larger second displacement region including the first displacement region based on the displacement modulated wave signal;
a selection section configured to select either one of the high-resolution displacement signal or the low-resolution displacement signal based on an unsteady-state response signal obtained by excluding a steady-state whirling displacement component from the high-resolution displacement signal or the low-resolution displacement signal; and
a bearing control section configured to control the magnetic bearing based on the displacement signal selected by the selection section.

2. The magnetic bearing vacuum pump according to claim 1 , further comprising:
a steady-state response calculation section configured to calculate a steady-state whirling radius based on the high-resolution displacement signal or the low-resolution displacement signal; and
a factor changing section configured to change the resolution multiplying factor K to any one of multiple values according to the steady-state whirling radius.

3. The magnetic bearing vacuum pump according to claim 1 , wherein
the first displacement signal generation section includes
a first bandpass filter having a first Q-value and configured to filter the displacement modulated wave signal,
an amplification section configured to amplify, by the resolution multiplying factor K, a signal having passed through the first bandpass filter,
a first AD conversion section configured to perform analog-to-digital conversion for the amplified signal, and
a reduction section configured to reduce the analog-to-digital converted signal with a reduction ratio lower than 1/the resolution multiplying factor, and

the first displacement signal generation section generates the high-resolution displacement signal based on the reduced signal,
the second displacement signal generation section includes
a second bandpass filter having a second Q-value less than the first Q-value and configured to filter the displacement modulated wave signal, and
a second AD conversion section configured to perform analog-to-digital conversion for a signal having passed through the second bandpass filter, and

the second displacement signal generation section generates the low-resolution displacement signal based on a signal output from the second AD conversion section.

4. A magnetic bearing vacuum pump comprising:
a magnetic bearing configured to magnetically levitate a rotor;
a first displacement signal generation section configured to amplify, by a resolution multiplying factor K of K>1, a displacement modulated wave signal modulated according to a displacement of the rotor from a predetermined position to generate a high-resolution displacement signal in a first displacement region including the predetermined position based on the amplified displacement modulated wave signal;
a second displacement signal generation section configured to generate a low-resolution displacement signal in a larger second displacement region including the first displacement region based on the displacement modulated wave signal;
a selection section configured to select either one of the high-resolution displacement signal or the low-resolution displacement signal;
a bearing control section configured to control the magnetic bearing based on the displacement signal selected by the selection section;
a steady-state response calculation section configured to calculate a steady-state whirling radius based on the high-resolution displacement signal or the low-resolution displacement signal; and
a factor changing section configured to change the resolution multiplying factor K to any one of multiple values according to the steady-state whirling radius.

5. The magnetic bearing vacuum pump according to claim 4 , wherein
the first displacement signal generation section includes
a first bandpass filter having a first Q-value and configured to filter the displacement modulated wave signal,
an amplification section configured to amplify, by the resolution multiplying factor K, a signal having passed through the first bandpass filter,
a first AD conversion section configured to perform analog-to-digital conversion for the amplified signal, and
a reduction section configured to reduce the analog-to-digital converted signal with a reduction ratio lower than 1/the resolution multiplying factor, and

the first displacement signal generation section generates the high-resolution displacement signal based on the reduced signal,
the second displacement signal generation section includes
a second bandpass filter having a second Q-value less than the first Q-value and configured to filter the displacement modulated wave signal, and
a second AD conversion section configured to perform analog-to-digital conversion for a signal having passed through the second bandpass filter, and

the second displacement signal generation section generates the low-resolution displacement signal based on the analog-to-digital converted signal.

6. A magnetic bearing vacuum pump comprising:
a magnetic bearing configured to magnetically levitate a rotor;
a first bandpass filter having a first Q-value and configured to filter a displacement modulated wave signal modulated according to a displacement of the rotor from a predetermined position;
an amplification section configured to amplify, by a resolution multiplying factor K of K>1, a signal having passed through the first bandpass filter;
a first AD conversion section configured to perform analog-to-digital conversion for the signal amplified by the amplification section;
a reduction section configured to reduce the signal analog-to-digital converted by the first AD conversion section with a reduction ratio lower than 1/the resolution multiplying factor;
a first displacement signal generation section configured to generate a high-resolution displacement signal in a first displacement region including the predetermined position based on the signal reduced by the reduction section;
a second bandpass filter having a second Q-value less than the first Q-value and configured to filter the displacement modulated wave signal;
a second AD conversion section configured to perform analog-to-digital conversion for a signal having passed through the second bandpass filter;
a second displacement signal generation section configured to generate a low-resolution displacement signal in a larger second displacement region including the first displacement region based on the signal analog-to-digital converted by the second AD conversion section;
a selection section configured to select either one of the high-resolution displacement signal or the low-resolution displacement signal; and
a bearing control section configured to control the magnetic bearing based on the displacement signal selected by the selection section.

7. The magnetic bearing vacuum pump according to claim 2 , wherein
the steady-state whirling radius when the resolution multiplying factor K is changed from a first value to a second value less than the first value is, by a predetermined hysteresis width, set greater than

Assignees

• Shimadzu Corp

Inventors

• Kozaki Junichiro

Classifications

• F16C32/0448

  by using the electromagnet itself as sensor, e.g. sensorless magnetic bearings · CPC title

• F04D29/058

  magnetic; electromagnetic · CPC title

• F04D19/048 Primary

  comprising magnetic bearings · CPC title

• F04D29/66

  Combating cavitation, whirls, noise, vibration or the like (gas-flow silencers for machines or engines in general F01N); Balancing (surge control F04D27/02) · CPC title

• F16C32/044

  Active magnetic bearings · CPC title