Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2003-08-29
2004-10-19
Nguyen, Tran N. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C318S114000, C318S128000, C318S649000, C417S423700, C417S423120
Reexamination Certificate
active
06806606
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic bearing device with a vibration restraining function, a magnetic bearing device with a vibration estimating function, and a pump device with the magnetic bearing devices mounted thereto. More specifically, the invention relates to a magnetic bearing device with a vibration restraining function, a magnetic bearing device with a vibration estimating function, and a pump device with the magnetic bearing devices mounted thereto, in which it is possible to realize a reduction in vibration in the apparatus system as a whole inclusive of the equipment associated with the vacuum pump without newly providing a vibration sensor.
2. Description of the Related Art
With the recent years' development of electronics, there is a rapidly increasing demand for semiconductors for forming memories, integrated circuits, etc.
Such semiconductors are manufactured, for example, by doping a semiconductor substrate of a very high purity with impurities to impart electrical properties thereto, or by stacking together semiconductor substrates with minute circuit patterns formed thereon.
The operation of manufacturing such semiconductors must be conducted in a high vacuum chamber in order to avoid the influences of dust, etc. in the air. This chamber is generally evacuated by a vacuum pump. In particular, a turbo-molecular pump, which is a kind of vacuum pump, is widely used since it entails little residual gas and is easy of maintenance.
A semiconductor manufacturing process includes a number of steps in which various process gases are caused to act on a semiconductor substrate, and the turbo-molecular pump is used not only to evacuate the chamber but also to discharge these process gases from the chamber.
Further, in an apparatus like an electron microscope, an turbo-molecular pump is used to create a high vacuum state in the chamber of the apparatus in order to prevent refraction, etc. of an electron beam due to the presence of dust or the like.
Such a turbo-molecular pump is composed of a turbo-molecular pump main body for sucking and discharging gas form the chamber of a semiconductor manufacturing apparatus, and electron microscope, or the like, and a control device for controlling the turbo-molecular pump main body.
FIG. 10
is a longitudinal sectional view of a turbo-molecular pump main body, and
FIG. 11
is a schematic diagram showing an apparatus system as a whole in which the turbo-molecular pump main body is used to evacuate a chamber.
In
FIG. 10
, a turbo-molecular pump main body
100
includes an outer cylinder
127
, on top of which there is formed an intake hole
101
. Provided inside the outer cylinder
127
is a rotor
103
having in its periphery a plurality of rotary blades
102
a
,
102
b
,
102
c
, . . . serving as turbine blades for sucking and discharging gas and formed radially in a number of stages.
At the center of the rotor
103
, there is mounted a rotor shaft
113
, which is supported in a levitating state and controlled in position, for example, by a so-called 5-axis control magnetic bearing.
Upper radial electromagnets
104
consist of four electromagnets arranged in pairs in X- and Y-axis directions, perpendicular to each other, and opposed to each other with the rotor shaft
113
therebetween. It is to be assumed that the X- and Y-axes are in a plane perpendicular to the axis of the rotor shaft
113
when the rotor shaft
113
is at a control target position of the magnetic bearing. Further, there is provided an upper radial sensor
107
consisting of four coils wound around cores and arranged in close proximity to and in correspondence with the upper radial electromagnets
104
. The upper radial sensor
107
detects radial displacement of the rotor
103
, transmitting a detection signal to a control device
200
shown in FIG.
11
.
The control device
200
is equipped with magnetic bearing feedback control means composed of a compensator
201
, an amplifier
202
, etc. In this control device
200
, excitation of the upper radial electromagnets
104
is controlled by the output of the amplifier
202
supplied through the compensator
201
having a PID adjusting function, on the basis of a displacement signal detected by the upper radial sensor
107
, thus performing adjustment of the radial position of the upper portion of the rotor shaft
113
.
The rotor shaft
113
is formed of a high-magnetic-permeability material (e.g., iron) and is adapted to be attracted by the magnetic force of the upper radial electromagnets
104
. Such adjustment is conducted independently in the X-axis direction and the Y-axis direction.
Further, lower radial electromagnets
105
and a lower radial sensor
108
are arranged in the same way as the upper radial electromagnets
104
and the upper radial sensor
107
. Like the radial position of the upper portion of the rotor shaft
113
, the radial position of the lower portion of the rotor shaft
113
is adjusted by the magnetic bearing feedback control means in the control device
200
.
Further, axial electromagnets
106
A and
106
B are arranged respectively on the upper and lower sides of a metal disc
111
provided in the lower portion of the rotor shaft
113
. The metal disc
111
is formed of a high-magnetic-permeability material, such as iron. To detect axial displacement of the rotor
103
, there is provided an axial sensor
109
, which transmits an axial displacement signal to the control device
200
.
The axial electromagnets
106
A and
106
B are excitation-controlled by the output of the amplifier
202
supplied through the compensator
201
, which has a PID adjusting function, of the control device
200
, on the basis of the axial displacement signal. The axial electromagnet
106
A magnetically attracts the metal disc
111
upwardly, and the axial electromagnet
106
B magnetically attracts the metal disc
111
downwardly.
In this way, in the control device
200
, the magnetic force the axial electromagnets
106
A and
106
B exert on the metal disc
111
is appropriately controlled by the magnetic bearing feedback control means, magnetically levitating the rotor shaft
113
in the axial direction and retaining it in the space in a non-contact state.
A motor
121
is equipped with a plurality of magnetic poles consisting of permanent magnets arranged circumferentially on the rotor side so as to surround the rotor shaft
113
. A torque component for rotating the rotor shaft
113
is imparted to these permanent magnet magnetic poles from the electromagnets on the stator side of the motor
121
, thereby rotating the rotor
103
.
Further, an RPM sensor and a motor temperature sensor (not shown) are mounted to the motor
121
, and the rotation of the rotor shaft
113
is controlled in the control device
200
in response to detection signals from the RPM sensor and the motor temperature sensor.
A plurality of stationary blades
123
a
,
123
b
,
123
c
, . . . are arranged so as to be spaced apart from the rotary blades
102
a
,
102
b
,
102
c
, . . . by small gaps. In order to downwardly transfer the molecules of exhaust gas through collision, the rotary blades
102
a
,
102
b
,
102
c
, . . . are inclined by a predetermined angle with respect to a plane perpendicular to the axis of the rotor shaft
113
.
Similarly, the stationary blades
123
are also inclined by a predetermined angle with respect to a plane perpendicular to the axis of the rotor shaft
113
, and extend toward the inner side of the outer cylinder
127
to be arranged alternately with the rotary blades
102
.
The stationary blades
123
are supported at one end by being inserted into gaps between a plurality of stationary blade spacers
125
a
,
125
b
,
125
c
, . . . stacked together in stages.
The stationary blade spacers
125
are ring-shaped members, which are formed of a metal, such as aluminum, iron, stainless steel, or copper, or an alloy containing such metal as a component.
In the outer periphery of the stationary blade spacers
125
, the outer cylinder
127
i
Fukami Hideo
Namiki Hirotaka
Ohtachi Yoshinobu
Adams & Wilks
BOC Edwards Technologies Limited
Nguyen Tran N.
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