JPS6399742A - Magnetic bearing integrating type motor - Google Patents

Abstract

PURPOSE:To permit the use of a magnetic bearing even in a large-size motor, by a method wherein a rotation driving electromagnet is used for the magnetic bearing in addition to a permanent magnet. CONSTITUTION:Electromagnets 50 are equipped for generating the driving force of the rotation of rotors 11, 12 and a supporting force of a rotary shaft 3 and are constituted of U-shape cores equipped with armature coils 40. The rotors 11, 12 are arranged at positions whereat two pieces of annular permanent magnets 2 are opposed. to the two ends of said U-shape core and are fixed integrally to sleeve-type cores 221, 222. The sleeve-type cores 221, 222 are fixed integrally to the rotary shaft 3. The eccentricity in the circumferential direction of the rotary shaft 3 is detected by a sensor, not shown in a diagram, and the rotary shaft 3 is kept in a center by operating the electric current of the electromagnets 50. The positional control in the axial direction of the rotary shaft 3 is effected by the permanent magnet 30 and the electromagnet 53 in the same manner. A ball bearing 25 for emergency is provided for a case, in which the electromagnet does not effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor equipped with a magnetic bearing.

[Prior art]

It is well known that bearings (hereinafter referred to as "magnetic bearings") that support a rotating shaft using magnetic force have been used in motor bearings.

An overview of this magnetic bearing will be explained below with reference to FIG. 3, which illustrates a plushless DC motor.

The figure shows a half cross section of the main part to explain the outline of a plushless DC motor. The permanent magnets 2 constituting the rotor 1 are ring-shaped permanent magnets with predetermined polarities arranged around the rotating shaft 3. An armature coil 4 and an iron core 5 for rotating the rotor 1 are provided around the permanent magnet 2.

The magnetic bearing 6 is provided on the rotating shaft 3 on both sides of the rotor 1, and is made of an iron core in which a laminated magnetic pole 7 is arranged in a ring shape and an excitation coil 8 is provided at a predetermined interval around the ring. A plurality of electromagnets 9 are arranged. Further, a displacement meter 12 is provided to detect displacement of the rotor in the radial direction. The magnetic attractive force between the laminated magnet 7 and the electromagnet 9 feeds the displacement signal from the displacement meter 12 through an appropriate compensation circuit to the power amplifier circuit of the electromagnetic pole 9, thereby generating a restoring force and a damping force for the rotor. As a result of the control, the rotating shaft 3 is supported by the bearing of the electromagnet 9 floating above the surface 10.

Such magnetic bearings do not require lubricating oil because they have no friction surfaces, and can be advantageously used in bearings for ultra-high-speed rotating bodies, bearings for rotating bodies rotating in vacuum, etc., so they can be used, for example, in outer space. It can be advantageously used for motors, etc.

However, with magnetic bearings, the higher the rotation of the rotor, the more
In addition, the larger the bearing, the stronger the attraction force required, but the components such as the iron core, permanent magnet, and coil all need to be made of materials with high specific gravity, which increases weight and increases the size of the bearing. There is a problem with becoming. Therefore, this problem becomes a particular drawback when a large number of devices are housed in a narrow space or when the motor is made small.

[Purpose of the invention]

The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor having a magnetic bearing that is smaller and lighter than conventional motors.

(Configuration of the invention) The configuration of the motor of the present invention for achieving the above object is as follows:
A drive unit consisting of a rotor consisting of a permanent magnet whose outer peripheral surface has a predetermined polarity and is formed concentrically around a rotating shaft, and a plurality of drive electromagnets arranged around the rotor that generate a rotating magnetic field. , an electric current that is extended to the position where the bearing of the rotating shaft is to be disposed, and that generates a magnetic field that is superimposed on the rotating magnetic field for rotational driving of the electromagnet and acts on the permanent magnet to apply a controlled attractive force for the bearing. It is characterized by passing through.

The driving electromagnet that provides the rotational driving force of the motor of the present invention to the rotor causes the rotor to levitate from the electromagnet surface by applying a magnetic force that provides a controlled attraction force for a bearing to the rotor. The motor does not require conventional bearings such as ball bearings.

When implementing the present invention, it is essential to provide a control device that detects the circumferential position and eccentricity of the rotating shaft of the motor, calculates optimal correction conditions, and controls the magnetic field strength of the bearing electromagnet. This rotary shaft position detection device can be of the same type as a detection device using a Hall element or the like that is essential for conventional ACC brushless morph rotation control, and can be used in common with this.

〔Example〕

Hereinafter, the present invention will be specifically explained by way of an example in comparison with the drawings.

FIG. 1 is a vertical cross-sectional view showing an outline of an embodiment implemented using a brushless DC motor connected to a fan, and FIG. 2 is a partial view taken along line A--A of the magnet portion. Note that the same numbers are given to the same members as those of the motor shown in FIG. 3, and explanations thereof are omitted.

In the figure, the motor 15 and fan 16 of this embodiment are assembled integrally, the impeller 17 of the fan 16 is fixed to the rotating shaft 3 with a nut 18, and the motor 1
5, rotors 11 and 12 are provided at a predetermined distance, and drive portions are provided at two locations by fitting the rotors 1° and 12 from both sides of a flange portion 20 provided on the rotating shaft 3.

Next, the rotor 11, 12 and the electromagnet 5o will be explained. The electromagnet 5o generates a rotational driving force for the rotors 11 and 12 and a force for supporting the rotating shaft 3, and is composed of a U-shaped iron core equipped with an armature coil 4°. and 12 are integrated with two ring-shaped permanent magnets 2 arranged at positions corresponding to the two ends of the U-shape and fixed to sleeve-shaped iron cores 221 and 222. The sleeve-shaped cores 221 and 22
2 is fitted and fixed to the rotating shaft 3 and is integrated therewith. Therefore, the axial cross-sectional shape of the rotor 3 is
Similarly, it has a U-shape. The ring-shaped permanent magnet 2 is magnetized in the radial direction, as shown in FIG. 2, like a normal DC motor, and has a distribution in which the north and south poles are reversed in the circumferential direction.

The motor 15 of this embodiment includes, in addition to the electromagnet 5o, an emergency bearing 25 made of a ball bearing and an axial magnetic bearing 26 arranged in the same position as a normal bearing. The emergency bearing 25 acts as a stopper when the rotating shaft 3 moves eccentrically or axially beyond a predetermined value, and is normally made so as not to come into contact with the rotating shaft 3.

However, when the motor 15 is not operating, the rotating shaft 3 is supported by the emergency bearing 25. In this example,
The sleeve-shaped cores 221 and 222 are connected to the emergency bearing 2.
A stopper surface 27 in the radial direction and a stopper surface 28 in the axial direction of the rotary shaft 3 are formed by extending to 1 at 5.

The axial magnetic bearing 26 is provided at the end of the rotating shaft 3 opposite to the fan 16, and is caused by the extended peripheral edge 29 of the iron core 222 and the permanent magnet 30 provided at the axial center.
A permanent magnet part 31 having a positive cross-sectional shape, an electromagnet 33 which also has an E positive cross-sectional shape and has a coil 32 provided therein, and an axial position sensor of the rotating shaft 3 provided in the center of the electromagnet 33. It consists of 34.

A sensor 35 that detects the phases of the rotors 11 and 12 in order to control the timing of the rotating magnetic field created by the electromagnet 5o is composed of a Hall element, and is located close to the ring-shaped permanent magnet 2 between each electrode 5o. It is located in

This sensor 35 is also used as a sensor for detecting the eccentricity of the rotating shaft 3, and also has the function of feeding back to the compensation circuit of the magnetic bearing to generate a control signal, as will be described later. In the motor 15 of this embodiment, four phase sensors 35 are arranged so that the circumferential position of the rotating shaft 3 and the magnitude and direction of eccentricity can be detected.

Note that 39 is a ring-shaped member made of a non-magnetic material that is located between two adjacent permanent magnets 2 and holds them together, 40 is a body casing that also serves as a fixing member for the electromagnet 5°, and 41 is an emergency bearing 25. ．． The supporting member of the electromagnet 5o and the mounting of the fan 16 are a partition wall that also serves as a member, 42 is the electromagnet 5
o' and a casing that also serves as a support member for the emergency bearing 25, 43 a casing that also serves as a support member for the electromagnet 33, and 44 a casing for the fan 16.

Next, the operation of the motor 15 of this embodiment will be explained.

When a switch (not shown) of the motor 15 is turned on, the sensor 35 detects the magnitude and direction of eccentricity in the radial direction and the circumferential position of the rotating shaft 3, and the sensor 34 detects the axial position of the rotating shaft 3. These are fed back to a compensation circuit and a power amplification circuit (not shown), and a control current is given to each electromagnet 5o and 33 as a bearing to keep the rotating shaft 3 at a predetermined position in the radial and axial directions. The child 3 floats up from the emergency bearing 25. At the same time, a rotational driving current is applied to the armature coil 4o, and a rotating magnetic field is generated by superimposing a current for control on the bearing, and the rotating shaft 3 starts rotating, and the impeller 1 of the fan 16
7 is followed and the air blowing is started. Note that the white arrows in FIG. 1 indicate the direction of air flow.

Now, when a disturbance force acts on the rotating shaft 3 while the motor 15 is operating and the rotating shaft 3 deviates from a predetermined position in the radial direction, the sensor 35 detects the magnitude and direction of the eccentricity, and this signal is sent to the compensation circuit. A current is fed back to the power amplifier circuit and a phase advance control signal is applied to the electromagnet 5o, and a force acts between the electromagnet 5o and the permanent magnet 2 to return the rotating shaft 3 to its original position, so that the fixed position is maintained. be able to.

The electromagnet 5o has two pairs of magnetic poles that attract the rotor 3 in opposite directions, and are arranged in directions perpendicular to each other.
In the parallel state, the paired magnetic poles exert equal and opposite attractive forces on the rotor 3 and are balanced.

Now, when a disturbance force acts on the rotor 3 and causes eccentricity,
The compensation circuit generates a control signal that disrupts the balance of this attractive force and stably returns the rotating shaft 3 to its original position against the disturbance force. Therefore, the electromagnets 5o are normally operated to generate an attractive force.

If a large disturbance force acts on the abnormal Q and it is no longer possible to counter this disturbance force only by adjusting the balance of the attractive force, a repulsive force against the permanent magnet 2 is generated in one of the magnetic poles of the pair to create a larger restoring force. cause

Further, in the axial magnetic bearing 26, the direction and strength of the current flowing through the exciting coil 32 are controlled based on the detection signal of the position sensor 34 so as to maintain the rotating shaft at a predetermined axial position.

In this case, as in the case of radial bearings, the principle is to control the suction force, but in some cases, repulsive force may be used to obtain a larger restoring force.

As explained above, the motor 15 of this embodiment is compact because the driving part directly serves as a bearing, so the axial length can be reduced, and during steady rotation, the motor 15 is compact. When the rotating part constituted by the shaft 3 is floating in space and rotating, and when some force acts and the rotating shaft 3 deviates from the center line, the electromagnet 5o
By controlling the attractive force acting between the ring-shaped permanent magnet 2o and the ring-shaped permanent magnet 2o, a pushing force can be applied to the center line. Since it does not work, it can be rotated.

Moreover, when an abnormal force acts and the eccentricity exceeds a predetermined value, the emergency bearing prevents further eccentricity, thereby avoiding a collision that could lead to failure. Furthermore, since the axial bearing of the rotating shaft 3 is also a magnetic bearing 26, the motor 15 of this embodiment can be rotated at high speed without any need for lubricating oil.

〔Effect of the invention〕

The motor of the present invention comprises a rotor consisting of a permanent magnet having an outer peripheral surface formed concentrically around a rotating shaft and having a predetermined polarity, and a plurality of driving electromagnets that generate a rotating magnetic field around the rotor. is installed in a position that also functions as a bearing,
Since the electromagnet generates a magnetic field that is superimposed with a rotating magnetic field and causes a controlled attraction to act on the permanent magnet so that it acts as a bearing, it is possible to omit the bearing that is conventionally provided in any motor. Therefore, there is no loss of energy due to friction, the length in the direction of the rotating shaft can be shortened, and it is possible to achieve the effects of being lightweight and compact.

Therefore, the motor of the present invention can be made small and lightweight for the same output, and is therefore useful as a small motor for space equipment, for example.

[Brief explanation of the drawing]

Fig. 1 is a half-sectional view showing an outline of an embodiment using a motor that drives a fan, Fig. 2 is a partial view taken along the line A-A of the magnet part in Fig. 1, and Fig. 3 is a conventional magnetic bearing. 1 is a half-sectional view showing an outline of a DC motor equipped with a DC motor. 1.11.12...Rotor, 2...Permanent magnet, 3.
...Rotating shaft, 4...Amateur coil, 5...Electromagnet, 15...Motor, 16...Fan, 17...
Impeller, 22... Sleeve-shaped core, 26... Axial magnetic bearing. Figure 2 Figure 3

Claims (1)

[Claims] A drive unit consisting of a rotor consisting of a permanent magnet whose outer peripheral surface has a predetermined polarity and is formed concentrically around a rotating shaft, and a plurality of drive electromagnets arranged around the rotor that generate a rotating magnetic field. , the bearing of the rotating shaft is extended to a position where it is to be disposed, and a current is applied to the electromagnet to generate a magnetic field that is superimposed with a rotating magnetic field for rotational driving and exerts a controlled attraction force on the permanent magnet for the bearing. A motor with an integrated magnetic bearing that is characterized by its ability to communicate.