JPH09137827A - Magnetic bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of a cost as shaft vibration is suppressed by a method wherein radial magnetic bearings are arranged at two adjoining parts of a turbine disc on which a fluid force is apt to be exerted as disturbance and the two bearings are driven by one and the same compensating circuit and a servo amplifier. SOLUTION: A turbine disc 2 is mounted on a rotary shaft 1 and through inflow of high pressure gas to the vanes thereof, drive is effected and the rotary shaft 1 is supported in a non-contact manner by radial magnetic bearings 3A and 3B. The magnetic bearings 3A and 3B comprise a rotor yoke 4; an electromagnet stator 6 attached to a casing 5; displacement sensors 7A and 7B; a compensating circuit 9 to control a magnetic suction force exerted between the rotor yoke 4 and the electromagnet stator 6 based on a displacement signal; and a servo amplifier 10. Since the magnetic bearings 3A and 3B are arranged at the two adjoining parts of the turbine disc 2, shaft vibration is suppressed. Since the two magnetic bearings 3A and 3B are driven by one and the same compensating circuit 9 and the servo amplifier 10, the increase of a cost due to the increase of the number of control parts and the servo amplifiers is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing used in a fluid machine such as a turbine drive.

[0002]

2. Description of the Related Art When a fluid machine supported by magnetic bearings is driven by a turbine, a turbine disk is attached to a rotary shaft, and high-pressure gas is introduced into the blades of the turbine disk for driving. In the usual case, magnetic bearings are provided near (but not necessarily near) the turbine disk.

[0003]

However, since the turbine blows high pressure gas from the outside, it is considered that the fluid force considerably acts as a disturbance. Therefore, in order to suppress shaft vibration, it is necessary to firmly hold around the turbine disk. Therefore, radial magnetic bearings may be provided on both adjacent portions of the turbine disk or the like.
However, if left as it is, the number of radial bearings will increase, and the number of control units and servo amplifiers that drive them will increase,
The cost is high.

Therefore, the present invention has been made for the purpose of providing a magnetic bearing which suppresses axial vibration around a turbine disk and which does not increase the cost due to an increase in the number of control units and servo amplifiers. It is a thing.

[0005]

Therefore, according to the present invention, there is provided a magnetic bearing used in a fluid machine driven by a turbine, the rotor yoke being made of a magnetic material fixed to a rotary shaft, and the rotor yoke. From the displacement sensor for measuring the relative displacement between the rotating shaft and the casing, the electromagnet stator having a coil for generating a magnetomotive force, which is attached to the casing at a minute distance from the displacement sensor. In a radial magnetic bearing including a compensating circuit for controlling a magnetic attraction force acting between the rotor yoke and the electromagnet stator based on a signal and a servo amplifier, both of a turbine disk and the like in which a fluid force easily acts as a disturbance. A magnetic bearing in which the radial magnetic bearings are provided in adjacent portions, and both radial magnetic bearings are driven by the same compensation circuit and servo amplifier It was.

This is a method of connecting the windings for electromagnets that generate control force in the same direction in series to the servo amplifier in both radial magnetic bearings, or an electromagnet that generates control force in the same direction in both radial magnetic bearings. There is a method to connect the windings for use in parallel to the servo amplifier.

As for the sensor, a displacement sensor is provided near each of the radial magnetic bearings, and a servo amplifier is driven based on the average output of the signals, and a servo based on one representative displacement sensor signal is used. There is a method of driving the amplifier.

By providing radial magnetic bearings on both adjacent portions of the turbine disk or the like respectively, axial vibration around the turbine disk is suppressed, and both radial magnetic bearings are driven by the same compensating circuit and servo amplifier. Prevents cost increase due to an increase in the number of servo amplifiers.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention,
A turbine disk 2 is attached to the rotary shaft 1,
High-pressure gas is made to flow into the blade to drive it. The rotating shaft 1 is supported by radial magnetic bearings 3A and 3B in a non-contact manner.

The magnetic bearings 3A and 3B include a rotor yoke 4 made of a magnetic material fixed to the rotary shaft 1 and the rotor yoke 4.
And a displacement sensor 7A, 7B for measuring relative displacement between the rotary shaft 1 and the casing 5, which is attached to the casing 5 at a minute distance from the electromagnet stator 6 having a coil for generating a magnetomotive force. And this displacement sensor 7A,
It is composed of a compensating circuit 9 and a servo amplifier 10 for controlling the magnetic attraction force acting between the rotor yoke 4 and the electromagnet stator 6 based on the displacement signal from 7B. 8
Is a sensor amplifier that amplifies the displacement signal from the displacement sensor 7.

The radial magnetic bearings 3A and 3B are provided at both adjacent portions of the turbine disk 2 where the fluid force is apt to act as a disturbance, and the radial magnetic bearings 3A and 3B have the same compensation circuit 9 and servo. Amplifier 1
It is driven by 0.

In the embodiment shown in FIG. 1, in both radial magnetic bearings 3A and 3B, when the x and y coordinates are set in the same direction, that is, at right angles to each other in the radial direction, the control force is in the + direction of x, for example. The windings for the electromagnet that generate the are connected in parallel.

As described above, since the radial magnetic bearings 3A and 3B are respectively provided on both adjacent portions of the turbine disk 2, axial vibration around the turbine disk can be suppressed.
Moreover, both radial magnetic bearings 3A and 3B are connected to the same compensation circuit 9
Further, since the servo amplifier 10 is used for driving, it is possible to prevent an increase in the number of control units and servo amplifiers and increase in cost.

As for the displacement sensor, the displacement sensor 7 is provided near each of the radial magnetic bearings 3A and 3B.
There are a method in which A and 7B are provided and the servo amplifier 10 is driven based on the average output of the signals, and a method in which the servo amplifier 10 is driven based on the signal of one representative displacement sensor.

FIG. 2 shows a second embodiment of the present invention,
In this embodiment, in both radial magnetic bearings 3A and 3B, electromagnet windings that generate control force in the same direction are connected in series to the servo amplifier 10. The other structure is the same as that of the first embodiment shown in FIG. 1, and the operation is the same as that of the first embodiment shown in FIG.

[0017]

Industrial Applicability According to the present invention, radial magnetic bearings are provided respectively on both adjacent portions of a turbine disk or the like where fluid force is apt to act as a disturbance, and both radial magnetic bearings are driven by the same compensation circuit and servo amplifier. Therefore, while suppressing the shaft vibration around the turbine disk, it is possible to prevent the number of control units and servo amplifiers from increasing and the cost becoming expensive.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a radial magnetic bearing portion showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a radial magnetic bearing portion showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rotating shaft 2 ... Turbine disk 3A, 3B ... Radial magnetic bearing 4 ... Rotor yoke 5 ... Casing 6 ... Electromagnet stator 7A, 7B ... Displacement sensor 8 ... ..Sensor amplifier 9 ... Compensation circuit 10 ... Servo amplifier

Claims (5)

[Claims] 1. A magnetic bearing used in a fluid machine such as a turbine drive, comprising: a rotor yoke made of a magnetic material fixed to a rotating shaft; and a casing at a minute distance from the rotor yoke. An electromagnet stator provided with a coil for generating a magnetomotive force, a displacement sensor for measuring relative displacement between the rotary shaft and the casing, the rotor yoke and the rotor based on a displacement signal from the displacement sensor. In a radial magnetic bearing equipped with a compensating circuit for controlling a magnetic attraction force acting between electromagnet stators and a servo amplifier, the radial magnetic bearings are respectively provided at both adjacent portions such as a turbine disk where a fluid force easily acts as a disturbance. , A magnetic bearing characterized by driving both radial magnetic bearings by the same compensation circuit and servo amplifier. 2. The magnetic bearing according to claim 1, wherein in both radial magnetic bearings, electromagnet windings that generate a control force in the same direction are connected in series to a servo amplifier. 3. The magnetic bearing according to claim 1, wherein in each of the radial magnetic bearings, electromagnet windings that generate a control force in the same direction are connected in parallel to a servo amplifier. 4. The magnetic bearing according to claim 1, wherein a displacement sensor is provided near each of the radial magnetic bearings, and the servo amplifier is driven based on the average output of the signals from the displacement sensors. 5. The servo amplifier is driven based on a signal from one of the representative displacement sensors.
And 3 magnetic bearings.