JPH08200365A - Active magnetic bearing system - Google Patents

Abstract

PURPOSE: To protect an auxiliary bearing by operating a switching device via the action of an emergency detection circuit section detecting an emergency state such as a power failure, and reducing the speed of a rotor when the emergency state occurs. CONSTITUTION: Permanent magnets 24 are fitted to the outer periphery of a rotary shaft 21, and brake coils 25 wound around the permanent magnets 24 are provided at the prescribed intervals with the permanent magnets 24. A resistor 26 and a switching element 27 are connected to each brake coil 25 to form a closed circuit, and an emergency detection circuit 28 is provided for operating the switching element 27 to drive the closed circuit when an emergency such as a power failure occurs. The resistor 26 is used for dissipating the current induced in the brake coil 25 when the magnetic flux generated from the permanent magnet 24 interlinks with the brake coil 25 as Joule's heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active magnetic bearing system, and in particular, it is possible to reduce the load on an auxiliary bearing by consuming a high rotational inertia energy of a rotating body by a separate energy consuming means. The present invention relates to an active magnetic bearing system capable of protecting an auxiliary bearing by rapidly reducing the speed of a rotating body in the event of an emergency such as a power failure.

[0002]

2. Description of the Related Art Generally, an active magnetic bearing system is a device that levitates and holds a rotating body by a magnetic force of an electromagnet so that the rotating body can rotate without mechanical contact. It consists of a radial magnetic bearing and an axial magnetic bearing for axial retention.

Such active magnetic bearing systems are mainly used in the field of aerospace machinery, laboratory equipment or industrial machinery, relying on small-scale custom production and required in such specific fields. It has evolved as a structure. However, today, the demand for magnetic bearings is rapidly increasing as a component of mass-produced products with the development of technology, and particularly high precision and various degrees of freedom of movement are required.

FIG. 4 attached herewith shows an example of a conventional active magnetic bearing system. If you refer to this,
The conventional active magnetic bearing system is composed of a magnetic bearing 12 fitted to a predetermined portion of the rotary shaft 11 and an auxiliary bearing 13 fitted to one end of the rotary shaft 11. The magnetic bearing 12 includes a core 12c having a predetermined shape and a winding coil 12 wound around the core 12c.
It consists of w. That is, the core 12c has an ordinary donut shape, and a plurality of magnetic pole protrusions (not shown) having a symmetrical structure or an equiangular structure are formed on the inner peripheral surface of the core 12c. The winding coil 12w is wound around each of the plurality of magnetic pole protrusions.

Further, the auxiliary bearing 13 is provided with a cylindrical housing 13h, and a dry bearing member for dissipating the rotational inertia energy of the rotary shaft 11 as heat energy due to friction at a contact portion between the housing 13h and the rotary shaft 11. 14 and 15 are provided. A wear preventing member 16 for preventing wear of the dry bearing members 14 and 15 is provided between the dry bearing members 14 and 15. Further, the rotary shaft 11 and the dry bearing members 14, 1 are provided on one end side of the housing 13h.
A cooling pin 17 for cooling the heat generated by the friction of No. 5 is provided and fixed by a fixing member 18.

In the conventional magnetic bearing system having such a structure, the winding coil 12 is driven by an external power source.
When a current flows through w, a magnetic field is formed around the winding coil 12w. Therefore, the ferromagnetic core 12c is magnetized to form an electromagnet, and the rotating shaft 11 is rotated by the magnetic force generated from the plurality of magnetic pole protrusions on the inner peripheral surface of the core 12c.
It comes to surface without contacting 2c. Then, in such a levitated state, the rotary shaft 11 normally rotates at high speed.

[0007]

However, such a conventional magnetic bearing system consumes high rotational inertia energy of the rotating shaft 11 rotating at high speed in a form of radiating heat energy due to friction in the auxiliary bearing 13. , The rotation shaft 11 is decelerated and stopped. Therefore, dust is generated due to wear of the dry bearing members 14 and 15, and the dry bearing members 14 and 1
5 has a disadvantage that durability is lowered.

The present invention was created to solve the above-mentioned problems, and reduces the load on the auxiliary bearing by consuming the high rotational inertia energy of the rotating body by means of a separate consuming means. By rapidly reducing the speed of the rotating body in the event of an emergency such as a power outage,
It is an object to provide an active magnetic bearing system capable of protecting an auxiliary bearing.

[0009]

In order to achieve the above object, an active magnetic bearing system of the present invention protects a magnetic bearing for floating and holding a rotating shaft in a non-contact manner. In an active magnetic bearing system including an auxiliary bearing for rotating a rotating shaft, at least one permanent magnet is provided at a predetermined portion of the rotating shaft, and at least one break coil is used to induce an electromotive force by a magnetic flux from the permanent magnet. Is provided adjacent to the permanent magnet, and the break coil constitutes a closed circuit with a resistance element and a predetermined switching device for consuming electric energy due to the electromotive force induced in the coil, and the switching device has a function such as power failure. It is characterized in that it is configured to operate by the operation of the emergency detection circuit unit that detects an emergency situation.

[0010]

[Operation] By consuming the high rotational inertia energy of the rotating body by the break coil and the resistance element forming the closed circuit, the speed of the rotating body is sharply reduced to reduce the load on the auxiliary bearing and to prevent the occurrence of power failure. By rapidly reducing the speed of the rotating body and protecting the auxiliary bearing in the event of an emergency, the life of the magnetic bearing can be extended.

[0011]

The present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, an active magnetic bearing system according to the present invention is a device for floating and holding a rotating shaft 21 in a non-contact manner, and a ferromagnetic core 22c.
And winding coil 22w wound around its core 22c
Magnetic bearing 22 and its magnetic bearing 2
An auxiliary bearing 23 for protecting 2 is fitted to a predetermined portion of the rotary shaft 21. A device for converting rotational inertia energy generated when the rotary shaft 21 rotates into electric energy and consuming it is provided at still another predetermined portion of the rotary shaft 21. That is, a plurality of permanent magnets 24 are attached to the outer peripheral surface of the rotary shaft 21 as shown, and a plurality of break coils 25 in the form of winding coils are provided around the plurality of permanent magnets 24. And a predetermined distance from each other. A resistor 26 and a switching element 27 are connected to the break coil 25 to form one closed circuit, and the switching element 27 is operated to drive the closed circuit when an emergency situation such as a power failure occurs. 28 are provided. Here, the resistor 26 causes Joule heat (H = 0.24I ² Rt cal) to be consumed by the magnetic flux generated from the permanent magnet 24 interlinking with the break coil 25 and the current induced in the break coil 25 is consumed. It is for.

On the other hand, FIG. 3 shows a break coil according to another embodiment of the present invention and its peripheral portion. This embodiment is basically the same as the embodiment described with reference to FIGS. It is almost the same. Therefore, description of the same device element will be omitted.

That is, in the embodiment described with reference to FIGS. 1 and 2, the break coil 25 itself is provided in the form of a winding, whereas as shown in the embodiment of FIG. A yoke 49 having a plurality of protrusions 49t
And the break coil 45 has a plurality of protrusions 4
The difference is that it is wound on 9t. Here, since the yoke 49 having such a protrusion 49t provides a path for the magnetic flux emitted from the permanent magnet 44 to form a magnetic circuit, the magnetic flux flows through the protrusion 49t, so that a break coil is generated. The amount of interlinkage magnetic flux with 45 increases. If the amount of interlinkage magnetic flux increases, the induced electromotive force (e = -d
The size of φ / dt [V]) also increases, so that the thermal energy consumption due to Joule heat naturally increases, and the rotational inertia energy of the rotary shaft 41 decreases significantly. As a result, the rotation speed of the rotating shaft 41 is rapidly reduced, and the rotating shaft 4
1 will stop within a short time. This reduces the burden on the auxiliary bearing, which results in protection of the auxiliary bearing and the magnetic bearing. In addition, the break coil 45 is connected to the yoke 4 in this way.
The break coil 45
The installation state of is more stable.

Next, the operation of the active magnetic bearing system of the present invention having the above structure will be briefly described with reference to FIG.

The winding coil 22 is supplied with power from the outside.
When a current flows through w, a magnetic field is formed around the winding coil 22w. Therefore, the ferromagnetic core 22c is magnetized to form an electromagnet, and the magnetic force from the core 22c causes the rotating shaft 21 to float in a non-contact state with the core 22c. Then, the rotating shaft 21 rotates at a high speed in such a levitated state. When an emergency such as a power failure suddenly occurs during the normal operation, the emergency detection circuit unit 28 immediately detects the situation and activates the switching element 27. Then, along with the operation of the switching element 27, the break coil 25 and the resistor 26
The closed circuit composed of the switching element 27 is driven, and the current due to the induced electromotive force flows through the circuit, and Joule heat is generated by the resistor 26, whereby the rotational inertia energy of the rotary shaft 21 is rapidly reduced. Come to do. As a result, the rotation speed of the rotary shaft 21 is significantly reduced,
The rotating shaft 21 comes to stop within a short time. Therefore, the burden on the auxiliary bearing 23 is reduced, and the auxiliary bearing 23 and the magnetic bearing 22 are protected.

[0017]

As described above, in the active magnetic bearing system according to the present invention, Joule heat is generated and consumed by the high rotational inertia energy of the rotating body by the resistance element forming the break coil and the closed circuit. , The speed of the rotating body can be sharply reduced to reduce the load on the auxiliary bearing. Then, in the event of an emergency such as a power failure, the speed of the rotating body is rapidly reduced to protect the auxiliary bearing, so that the life of the magnetic bearing can be extended.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic device of an embodiment of an active magnetic bearing system according to the present invention.

2 is a side view showing a break coil of the active magnetic bearing system of FIG. 1. FIG.

FIG. 3 is a schematic view showing a schematic structure of a break coil and its periphery in another embodiment of the active magnetic bearing system according to the present invention.

FIG. 4 is a schematic diagram showing a schematic device of a conventional active magnetic bearing system.

[Explanation of symbols]

 11 rotating shaft 12 magnetic bearing 12c core 12w winding coil 13 auxiliary bearing 13h housing 14 dry bearing member 15 dry bearing member 16 wear preventing member 17 cooling pin 18 fixing member 21 rotating shaft 22 magnetic bearing 23 auxiliary bearing 24 permanent magnet 25 break coil 26 Resistance 27 Switching Element 28 Emergency Detection Circuit 41 Rotation Shaft 44 Permanent Magnet 45 Break Coil 49 Yoke 49t Projection

Claims (2)

[Claims] 1. An active magnetic bearing system comprising a magnetic bearing for floating and holding a rotating shaft in a non-contact manner, and an auxiliary bearing for protecting the magnetic bearing, wherein at least one portion of the rotating shaft is provided with a predetermined portion. A permanent magnet is provided, and at least one break coil is provided adjacent to the permanent magnet for inducing an electromotive force due to a magnetic flux from the permanent magnet, and the break coil is an electrical energy due to the electromotive force induced in the coil. A closed circuit is configured with a resistance element that consumes power and a predetermined switching device, and the switching device is configured to operate by the operation of an emergency detection circuit unit that detects an emergency situation such as a power failure. Magnetic bearing system. 2. A yoke having a plurality of protrusions having a predetermined height on its inner peripheral surface is provided around the permanent magnet, and the break coil is wound around the plurality of protrusions. The active magnetic bearing system according to claim 1, wherein: