JPH0681839A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To provide a thrust magnetic bearing device mounting a rotation sensor which has been miniaturized and compacted. CONSTITUTION:In a magnetic bearing device comprising a pair of magnetic poles 8 for supporting so as to interpose a thrust disk 7 vertically mounted on a rotary shaft 6 and an excitation coil 9, the magnetic bearing device is characterized by winding rotation sensor coils 5 partly onto the magnetic pole 8 of constituting the magnetic bearing device and by providing cut parts 3 in a part of the thrust disk 7 opposed to magnetic pole parts 2 of winding the rotation sensor coils 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing device, and more particularly to a thrust disk mounted perpendicularly to a rotary shaft,
The present invention relates to the structure of a rotation sensor in a thrust magnetic bearing device that floats and holds in a non-contact manner by a magnetic attraction force.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional thrust magnetic bearing device. A thrust disk 7 is vertically attached to the rotary shaft 6, and a magnetic pole 8 forming a pair of magnetic bearing devices is provided so as to sandwich the thrust disk 7.
An exciting coil 9 is wound around the magnetic pole 8. The thrust disk 7 is a target made of a disk-shaped magnetic material, and when an exciting current is passed through the annular exciting coil 9, a magnetic attraction force acts between the annular magnetic pole 8 and the thrust disk 7. By controlling this magnetic attraction force, that is, the exciting current of the exciting coil 9, the thrust disk 7 directly connected to the rotating shaft 6 is supported by floating and held between the pair of upper and lower magnetic poles 8 in a non-contact manner.

A rotation sensor 15 for detecting the number of rotations of the rotating shaft 6 which is supported by the thrust magnetic bearing and rotates is provided at a position different from the magnetic pole 8, the exciting coil 9 and the thrust disk 7 which constitute the thrust magnetic bearing. It was being done. That is,
As shown in FIG. 4, the rotation sensor disk 13 is attached to the rotation shaft 6.
Are directly connected to each other, a sensor target 10 made of a magnetic material is fixed to a part of the disk 13, and the sensor target 10 rotates together with the rotary shaft 6. In the portion of the disk 13 facing the sensor target 10, the disk 13
The rotation sensor core 11 around which the rotation sensor coil 12 is wound is arranged so as to be spatially separated. Since the magnetic circuit (inductance) of the rotation sensor core 11 seen from the rotation sensor coil 12 changes when the sensor target 10 rotating with the rotation shaft 6 passes through a portion facing the fixed sensor core 11, 12
A counter electromotive voltage pulse is generated at both ends of. This pulse is
The sensor target 10 is provided at a position where the sensor core 11 faces each other.
Appears every time the pulse passes, so the number of rotations of the rotary shaft can be detected by counting this pulse.

[0004]

The rotation sensor 15 in such a thrust magnetic bearing is separate from the thrust magnetic bearing and is directly connected to the rotation shaft of the rotation sensor disk 1.
3. Rotation sensor core 1 around which the rotation sensor coil 12 is wound
It was necessary to provide a member such as 1. For this reason, the space of each member which comprises the rotation sensor 15 was required. Further, although it is necessary to connect a cable to the rotation sensor coil 12, there is a problem that it is difficult to assemble because the space is limited because it is located away from the exciting coil 9 of the magnetic bearing.

In view of the above problems of the prior art, the present invention provides a magnetic bearing device equipped with a rotation sensor that does not require a special space for the rotation sensor and is easy to assemble.

[0006]

According to the present invention, there is provided a magnetic bearing device comprising a pair of magnetic poles and an exciting coil for supporting a thrust disk vertically mounted on a rotary shaft so as to sandwich the magnetic disc device. Some of the magnetic poles
The rotation sensor coil is wound, and a notch portion is provided in a portion of the thrust disk facing the magnetic pole portion around which the rotation sensor coil is wound.

[0007]

A rotation sensor coil is wound around a part of the magnetic poles forming the magnetic bearing device to form a rotation sensor magnetic pole, and a portion facing the sensor magnetic pole around which the rotation sensor coil is wound is placed on the thrust disk. The notch is partially provided. Therefore, when the thrust disk rotates as the rotary shaft rotates, a counter-electromotive force is generated in the rotary sensor coil each time the notch of the thrust disk passes through the opposing portion of the sensor magnetic pole around which the rotary sensor coil is wound. By generating a pulse of voltage and counting it, the number of rotations of the rotating shaft can be detected.

[0008]

1 is a sectional view taken along the main axis of a magnetic bearing device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA 'in FIG. The thrust magnetic bearing is composed of an annular magnetic pole 8 having a pair of upper and lower annular exciting coils 9 that support a thrust disk 7 vertically attached to the rotary shaft 6 so as to sandwich the thrust magnetic bearing. Is.

The thrust magnetic bearing includes a rotation sensor 1
And the above-mentioned magnetic pole 8 which constitutes a magnetic bearing.
Is a rotation sensor magnetic pole 2. A rotation sensor coil 5 is wound around the rotation sensor magnetic pole 2, and a magnetic circuit is formed between the rotation sensor magnetic pole 2 and a thrust disk 7 made of a magnetic material facing each other. On the other hand, a thrust disk 7 directly connected to the rotating shaft, which is supported by magnetic bearings so as to be sandwiched.
A cutout portion 3 is provided in a portion facing the rotation sensor magnetic pole 2. The notch 3 is a recess provided in the thrust disk made of a magnetic material, and the recess may be filled with a non-magnetic material.

The rotation sensor 1 operates as follows. The thrust disk 7 directly connected to the rotary shaft 6 is supported by the magnetic attraction force of the magnetic pole 8 so as to be levitated by the control current flowing through the exciting coil 9 forming the thrust magnetic bearing. In the rotation sensor magnetic pole 2 which is a part of the magnetic pole 8,
A magnetic circuit is formed between the thrust disk 7 and the thrust disk 7 which are spatially separated. When the rotary shaft 6 rotates, the thrust disk 7 directly connected to it also rotates, and the notch 3 that is a part of the thrust disk 7 also rotates around the rotary shaft 6.
When the cutout portion 3 passes through the facing portion of the fixed rotation sensor magnetic pole 2, the magnetic resistance (inductance) viewed from the rotation sensor coil 5 changes, so that the magnetic flux linked to the rotation sensor coil 5 changes. However, a counter electromotive voltage pulse is generated in the rotation sensor coil 5. Therefore, the number of rotations of the rotary shaft can be detected by counting the number of pulses.

At this time, since the magnetic flux of the magnetic pole 8 serving as the thrust magnetic bearing penetrates the rotation sensor magnetic pole 2, when the control current flowing through the exciting coil 9 forming the thrust magnetic bearing changes, the magnetic pole 8 and the rotation sensor magnetic pole 2 are changed. The magnetic flux of changes. Even if the control current changes, the rotation sensor coil 5 is arranged so as not to be affected by the change in the magnetic flux of the magnetic poles 2, 8 so as to sandwich the thrust disk 7, and the two rotations arranged so as to face each other. The sensor coils 5 are connected in series so that the counter electromotive voltage generated by the change in the magnetic flux of the control current is in the opposite direction. Since the rotation sensor coils 5 are connected in series as described above, the counter electromotive voltages of the rotation sensor coils 5 caused by the change of the control current act in the canceling direction, and the counter electromotive voltages generated by the notches 3 are added. Work toward you. Therefore, the pulse output as the rotation sensor at both ends of the rotation sensor coil 5 connected in series is not affected by the change in the control current.

In FIG. 3, the thrust displacement signal 16, the thrust control current signal 17, and the rotation sensor signal 18 are input to the cancel circuit 19, and the signal due to the change of the control current is extracted from the thrust signal 16 and the thrust control current signal 17.
A change amount of the thrust control current signal 17 is canceled by the thrust displacement signal 16 and a correct rotation speed signal is taken out from the rotation sensor signal 18. By such a process on the circuit, even if the rotation sensor magnetic pole 2 is provided in a part of the magnetic pole 8 that serves as the thrust magnetic bearing, a rotation pulse that is not affected by the change in the control current of the thrust magnetic bearing is extracted from the rotation sensor coil. be able to.

[0013]

As described above, according to the magnetic bearing device of the present invention, the magnetic poles of the rotation sensor are formed integrally with the magnetic poles of the thrust magnetic bearing, and the target of the rotation sensor cuts the thrust disk of the thrust magnetic bearing. It is formed as a notch. Therefore, the number of parts of the rotation sensor is reduced, the space required for the conventional rotation sensor is not required, and a compact and compact magnetic bearing device equipped with the rotation sensor is realized. Further, since the cable connected to the rotation sensor coil can also be arranged in the vicinity of the cable of the exciting coil of the bearing, the problem of space limitation for conventional assembly is solved, and a magnetic bearing device that can be easily assembled is provided. It was realized. That is, the conventional problem of space limitation for assembling is solved, the assembling is facilitated, and the magnetic bearing device which is not affected by the mounting posture of the pump and the thrust control current is realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic bearing device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a magnetic bearing device according to an embodiment of the present invention.

FIG. 3 is a block diagram of a rotation sensor circuit according to an embodiment of the present invention.

FIG. 4 is a sectional view of a conventional magnetic bearing device.

[Explanation of symbols]

 1,15 rotation sensor 2 rotation sensor magnetic pole 3 notch portion 5 rotation sensor coil 6 rotation shaft 7 thrust disk 8 magnetic pole 9 excitation coil 10 sensor target 11 rotation sensor core 12 rotation sensor coil 13 rotation sensor disk 16 thrust displacement signal 17 thrust control current Signal 18 Rotation sensor signal 19 Cancel circuit

Claims (1)

[Claims] 1. A magnetic bearing device comprising a pair of magnetic poles for supporting a thrust disk mounted perpendicularly to a rotary shaft so as to sandwich the magnetic disc and an exciting coil, wherein a part of the magnetic poles constituting the magnetic bearing device has a rotation. A magnetic bearing device, wherein a sensor coil is wound, and a notch portion is provided in a portion of the thrust disk facing a magnetic pole portion around which the rotation sensor coil is wound.