JPS63167120A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To surely prevent a protecting bearing from being damaged, by providing a ring member, which moves to the outside in the diametric direction by centrifugal force enabling a bearing clearance to be adjusted, mutually between bearing rings in a rotary part side of the protecting bearing comprising two ball bearings. CONSTITUTION:A protecting bearing 12 consists of two back-to-back combined single-row outer ring non separable angular full type ball bearings 13. An outer ring 16 of the two bearings 13 forms its opposed end surface in a protrusive shape, providing a diagonal inner tapered surface 16a and a diagonal outer tapered surface 16b. While a ring member 17 of shape dividing a circle equally into four parts is interposed between the opposed end surfaces of these tapered surfaces. The ring member 17, which forms its end surface opposed to the outer ring 16 into a recessed shape, provides a diagonally outer facing tapered surface 17a and a diagonally inner facing tapered surface 17b.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a magnetic bearing device.

Prior art and its problems FIG. 5 shows an example of a conventional magnetic bearing device, in which a cylindrical rotor (2) is arranged around a vertical fixed shaft (1). The rotor (2) has radial magnetic bearings (3) (4) and axial magnetic bearings (5) provided on the fixed shaft (1).
) (8) in a non-contact state, for example 3000
Rotates at a high speed of about 0 rpm.

Protective bearings (7) and (8) are provided at two locations above and below the fixed shaft (1) to receive the rotor (2) when it is stopped. Full ball bearings are used for each protective bearing (7) (8) to increase the load capacity, and their inner rings (7a) (8)
a) is fixed to a fixed shaft (1). When the rotor (2) is rotating normally, there is, for example, 0.0 mm between the rotor (2) and the protective bearings (7) and (8). There is a gap of about 1 to several 1. When the rotor (2) stops, the rotor (2) contacts and is received by the outer rings (7b) (8b) of the protective bearings (7) (8), and the rotor (2) is moved by the magnetic bearings ( 1) (4) (5) (6) etc., so as not to damage them by contacting them. By the way, when the magnetic bearing device stops in a normal state, the rotor (2) is gradually decelerated and comes into contact with the protective bearings (7) and (8) after reaching a considerably low speed.
)(8) will not be damaged. However, due to a power outage or other failure, the magnetic bearing (3) (4) (5) (6)
If it stops working, it will come into contact with the rotor (2), which is rotating at high speed, and the protective bearings (7) and (8), causing problems such as damage to the protective bearings (7) and (8). there were. This is considered to be due to the following reasons.

In other words, when the rotor rotating at high speed contacts the outer ring of the protective bearing, the outer ring also starts rotating at high speed, and the outer ring expands due to the centrifugal force of the balls and the outer ring itself.
Bearing clearance increases abnormally.

Therefore, the number of balls that come into contact with the inner ring decreases, and the number of rotations and revolutions of the balls decreases due to contact between balls that do not contact the inner ring. As a result, slipping occurs on the balls that come into contact with the inner ring, and due to high-speed rotation, the temperature of the balls and inner ring increases due to friction.
Bearings do not rotate normally due to problems such as a decrease in quenched hardness or abnormal wear and deformation.

In addition to the type of magnetic bearing device in which a cylindrical rotor rotates around a fixed shaft as described above, there is also a type in which a rotor shaft rotates inside a cylindrical fixed case. In this case, protective bearings are provided at two locations on the upper and lower sides of the case, and when the shaft stops, the shaft contacts and is received by the inner ring of the protective bearing.

However, in this case, when the magnetic bearing stops working due to a power outage or other failure, if the shaft rotating at high speed comes into contact with the inner ring of the protective bearing, the inner ring also starts rotating at high speed, creating a centrifugal force. As the inner ring expands, the bearing clearance decreases and becomes completely negative. Therefore, at high speed rotation, the balls come into contact with each other with excessive force, which may also damage the protective bearing.

An object of the present invention is to provide a magnetic bearing device that solves the above problems.

Means for Solving the Problems The magnetic bearing device according to the present invention supports a rotating part with a magnetic bearing in a non-contact state with respect to a fixed part, and a plurality of protective bearings that receive the rotating part when the rotating part is stopped are attached to a plurality of the fixed parts. In a magnetic bearing device installed at a location, the protective bearing consists of two ball bearings, and the bearing rings on the rotating part side of the protective bearing are moved radially outward by centrifugal force to adjust the bearing clearance. The ring member is provided with a ring member that is integral or divided into a plurality of parts.

If the rotating parts come into contact with the rings of the two ball bearings while rotating at high speed due to a power outage or other malfunction, these rings will also start rotating at high speed and expand due to centrifugal force, but the ring members will also expand at the same time. It starts rotating and moves radially outward due to centrifugal force, moving the bearing ring axially and adjusting the bearing clearance. Furthermore, since the bearing clearance is adjusted by a force corresponding to the centrifugal force, the bearing clearance will not increase or decrease excessively, and the ball bearing will operate normally and will not be damaged.

Embodiment Figures 1 and 2 show an example of a protective bearing (12) installed in a magnetic bearing device in which a cylindrical rotor (11) rotates around a fixed shaft (lO). .

This protective bearing (12) consists of two single row outer ring non-separable angular full ball bearings (13) in a back-to-back combination. Inner rings (14) of the two bearings (13) are fixed to a fixed shaft (10) via a spacer (15). 2 bearings (13
The opposing end surfaces of the outer ring (16) of ) are formed in a convex shape, and are provided with an inner tapered surface (16a) facing diagonally inward and an outer tapered surface (16b) facing diagonally outward. Furthermore, a ring member (17) in the shape of a circle divided into four equal parts is sandwiched between these opposing end surfaces.
The end face facing the outer ring (1G) of 7) is formed in a concave shape,
A diagonally outward tapered surface (17a) on the inside facing the tapered surface (lea) of the outer ring (16), and a diagonally inward tapered surface located on the outside facing the tapered surface (18b) of the outer ring (16). (17b) is provided.

If the rotor (11) is rotating normally, the rotor (11)
1) is supported in a non-contact state by a magnetic bearing (not shown), there is an appropriate clearance between the rotor (11) and the outer ring (16) of the bearing (12), and the outer ring ([6) is stationary. . At this time, the tapered surface (1°γa
) (17b) are in contact with the corresponding tapered surfaces (lea) (16b) of the upper and lower outer rings (16), and an appropriate preload is applied to the bearing (13). In addition, a ring member (17
) is sandwiched between the convex portions of the upper and lower outer rings (16), so the ring member (17) does not fall off.

Due to a power outage or other failure, the rotor (
11) comes into contact with the outer ring (IB) of the bearing (13), the outer ring (IB) also starts rotating at high speed and expands due to centrifugal force, increasing the bearing clearance.

However, at the same time, the ring member (17) also starts rotating at high speed, moves radially outward due to centrifugal force, and pushes the outer ring (1B) obliquely outward with its tapered surface (17a).

As a result, the two outer rings (1G) move vertically away from each other, that is, in the direction that reduces the bearing clearance, and the bearing (1G)
3) is loaded with an appropriate preload. For this reason, the ball (18
) rotates normally, the bearing (13) operates normally, and the bearing (13) will not be damaged due to seizure lock.

When the rotational speed of the rotor (11) gradually decreases and the amount of expansion of the outer ring (1B) due to centrifugal force decreases, the centrifugal force acting on the ring member (17) also decreases, and the preload load decreases. Then, when the rotor (11) stops, the bearing (13) returns to its original state.

Of the protective bearings of the magnetic bearing device, all parts may be made like the above-mentioned protective bearing (12), or only the parts that are particularly susceptible to damage may be made like the above-mentioned protective bearing (12). It's okay.

FIG. 3 shows a protective bearing (19) that is slightly different from the one described above. In FIG. 3, the same parts as those in FIG. 1 are given the same reference numerals.

In the case of Fig. 3, parts of the opposing end surfaces of the outer rings (16) of the two bearings (13) are formed in a concave shape, with a tapered surface (lee) on the inside facing diagonally outward and a tapered surface (lee) on the outside facing diagonally inward. A tapered surface (lad) is provided that faces toward. The ring member (20) has a disconnected diamond shape, and the end face facing the outer ring (16) has an obliquely inward tapered face (20a) located on the inner side and opposite to the tapered face (lee) of the outer ring (16). )
A tapered surface (20b) facing diagonally outward is provided on the outside and facing the tapered surface (LED) of the outer ring (16). The rest is the same as in FIGS. 1 and 2.

Figure 4 shows a protective bearing (21) that is slightly different from the above.
shows. In FIG. 4, the same parts as those in FIG. 3 are given the same reference numerals.

In the case of FIG. 4, a ring member (22) having a circular cross section is used in place of the ring member (20) of FIG. 3. The rest is the same as in the case of FIG.

The ring members (17), (20), and (22) are made of a suitable material such as metal, synthetic resin, or rubber. Furthermore, the angle of the tapered surface (wedge angle) is set so that an appropriate preload is always applied, taking into consideration the increase or decrease in the bearing clearance due to centrifugal force and the amount of axial movement of the outer ring due to the wedge angle.

In the above embodiment, a ring member having a circle divided into a plurality of parts is used, but it is also possible to use a completely circular integral ring member or a ring member obtained by cutting this ring member at the ltl point.

Furthermore, although the above embodiments relate to angular contact ball bearings, it goes without saying that the present invention can also be applied to deep groove ball bearings in which a certain degree of contact angle occurs due to the bearing clearance during actual use.

Effects of the Invention According to the magnetic bearing device of the present invention, damage to the protective bearing can be reliably prevented as described above. Also, 2
It only requires the use of individual ball bearings and ring members, and the structure is not much more complicated than conventional ones.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a protective bearing portion of a magnetic bearing device showing one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line ■-■ in FIG. 1, and FIG. FIG. 4 is a drawing corresponding to FIG. 1 showing an embodiment of the present invention, FIG. 4 is a drawing corresponding to FIG. 1 showing still another embodiment of the present invention, and FIG. 5 is a longitudinal sectional view showing a conventional magnetic bearing device. (lO)...Fixed shaft, (11)...Rotor, (12
) (19) (21)...protective bearing, (13)...
...Angular full ball bearing, (17) (20) (22
)...Ring member. that's all

Claims (1)

[Scope of Claims] A magnetic bearing device in which a rotating part is supported by magnetic bearings in a non-contact state with respect to a fixed part, and protective bearings are provided at a plurality of locations on the fixed part to receive the rotating part when the rotating part is stopped, The protective bearing consists of two ball bearings, and between the bearing rings on the rotating part side of the protective bearing, there is a bearing ring that can be moved radially outward by centrifugal force to adjust the bearing clearance. A magnetic bearing device provided with a ring member.