Vacuum pump

Patent metadata

Field	Value
Publication number	US-10001130-B2
Application number	US-92363010-A
Country	US
Kind code	B2
Filing date	Sep 30, 2010
Priority date	Sep 17, 2004
Publication date	Jun 19, 2018
Grant date	Jun 19, 2018

Abstract

A vacuum pump configured to exhaust gas includes an inductance gap sensor positioned oppositely near an end face of a rotational axis of a rotational body including a rotor; a plurality of individually formed recesses disposed at the end face facing the gap sensor at respectively different angular positions; and at least one ferromagnetic body disposed in at least one of the recesses. The ferromagnetic body has a Curie temperature approximately equal to an allowable temperature of the rotor. The gap sensor senses inductance changes associated with changes in magnetic permeability of the ferromagnetic body to detect a temperature of the rotor. One of the recesses where the ferromagnetic body is not disposed is a rotational number sensor target. Thus, a rotational number of the rotor is detected based on a change in inductance when the rotational number sensor target passes opposite the inductance sensor.

First claim

What is claimed is:

1. A vacuum pump configured to exhaust gas by rotating a rotor relative to a stator, comprising:
a first ferromagnetic body provided on an end face in a rotational axis direction of a rotational body including said rotor and provided coaxial with a rotational axis, the first ferromagnetic body having a Curie temperature equal to an allowable temperature, which generates a creep deformation in a rotor material of said rotor;
a second ferromagnetic body provided on the end face in the rotational axis direction of said rotor and provided coaxial with the rotational axis, the second ferromagnetic body having a Curie temperature higher than the Curie temperature of the first ferromagnetic body;
an inductance-type gap sensor provided to face said first and said second ferromagnetic bodies, and configured to detect a change in a magnetic permeability of said first and said second ferromagnetic bodies as inductance changes respectively; and
a controller having a motor drive control portion controlling a motor to drive the rotor, and to stop a rotation of the rotor when the change in the magnetic permeability of said second ferromagnetic body is detected, or when a total time, wherein the change of the magnetic permeability of said first ferromagnetic body is detected, exceeds a predetermined allowable time based on a creep life design of said rotor.

2. A vacuum pump according to claim 1 , further comprising a nut present at a lower end of the rotor,
wherein the first ferromagnetic body and the second magnetic body are present in a lower end part of the nut.

3. A vacuum pump according to claim 2 , wherein the first ferromagnetic body is in a ring-shape.

4. A vacuum pump according to claim 1 , wherein the controller further includes a magnet-bearing drive control portion controlling magnet bearings.

5. A vacuum pump configured to exhaust gas by rotating a rotor relative to a stator, comprising:
a first ferromagnetic body provided on an end face in a rotational axis direction of a rotational body including said rotor and provided coaxial with a rotational axis, the first ferromagnetic body having a Curie temperature equal to an allowable temperature, which generates a creep deformation in a rotor material of said rotor;
a second ferromagnetic body provided on the end face the rotational axis direction of said rotor, the second ferromagnetic body having a Curie temperature higher than the Curie temperature of the first ferromagnetic body;
an inductance-type gap sensor provided to face said first and said second ferromagnetic bodies, and configured to detect a change in a magnetic permeability of said first and said second ferromagnetic bodies as inductance changes respectively; and
a motor configured to drive the rotor, and to stop a rotation of the rotor when the change in the magnetic permeability of said second ferromagnetic body is detected, or when a total time, wherein the change of the magnetic permeability of said first ferromagnetic body is detected, exceeds a predetermined allowable time based on a creep life design of said rotor.

Assignees

• Kozaki Junichiro
• Shimadzu Corp

Inventors

• Kozaki Junichiro

Classifications

• F04D27/0292

  Stop safety or alarm devices, e.g. stop-and-go control; Disposition of check-valves · CPC title

• F04D29/058 Primary

  magnetic; electromagnetic · CPC title

• F04D19/042

  Turbomolecular vacuum pumps · CPC title