JP2000220637A - Touch-down bearing for magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the service life of a touch-down bearing by forming an indium film on at least the surface of a ball. SOLUTION: An indium film 16 is formed on at least the surface of the ball 10 of a touch-down bearing 3. The indium film or other solid lubricating film is formed on the inside surface or outside surface of the race of an inner ring 7 or outer ring 8 or the end surface connecting the inside surface to the outside surface. According to this, the problem of lubrication in the inner ring and outer ring of the touch-down bearing can be solved, and the rotation of the inner ring 7 or outer ring 8 can be quickly started by the solid lubricating film such as indium film provided on the outside surface (or inside surface) of the inner ring 7 or outer ring 8. Therefore, the durability of the touch-down bearing can be improved and made difficult to be damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch-down bearing for supporting a rotating member when a magnetic bearing device cannot be controlled.

[0002]

2. Description of the Related Art As shown in FIG. 1, for example, as shown in FIG. 1, touch-down bearings 3 and 4 are arranged at both ends of a rotating shaft 2 which is supported in a non-contact manner by a magnetic bearing 1, and sudden disconnection or power failure occurs. When the magnetic bearing 1 becomes uncontrollable due to, for example, the touchdown bearings 3 and 4 support the rotating shaft 2 to prevent damage to the magnetic bearing 1 and the rotating shaft 2.

That is, when the magnetic bearing 1 becomes uncontrollable or the like, the rotating shaft 2 rotating at a high speed shakes.
At this time, the rotating shaft 2 suddenly collides with the inner rings of the touchdown bearings 3 and 4, and this inner ring is forced to rotate rapidly at a high speed. Further, since there is a gap between the rotating shaft 2 and the touchdown bearings 3 and 4 (see FIGS. 2 and 4), the rotating shaft 2 moves freely within the movable range. For this reason, the impact load and the sudden acceleration are repeatedly generated in the touchdown bearings 3 and 4.

[0004] Touchdown bearing 3 of the above magnetic bearing device
When described with reference to FIG. 2, as a front combination of two angular ball bearings 5 and 6, both radial load and axial load are received. Each of the angular ball bearings 5 and 6 is formed by incorporating a plurality of balls 10 held by a retainer 9 between an inner ring 7 and an outer ring 8, and a gap 11 is formed on a combination surface of the inner rings 7 by grinding. The bearing is provided so that no preload is applied to the bearing due to thermal expansion of the inner ring.

[0005]

The above-mentioned touch-down bearing has been conventionally considered as an emergency use, so that even if the bearing becomes unusable by one or two touch-downs, it cannot be stopped. And it was. But,
To replace a touchdown bearing that has become unusable, disassemble the magnetic bearing device, replace the touchdown bearing,
Touch down gap between the inner or outer ring and the rotating part,
Since it is necessary to perform an operation of assembling the bearing device while adjusting the bearing clearance of the magnetic bearing with high precision, the operation is extremely troublesome. For this reason, recently, there has been a demand for a structure capable of increasing the durability of the touch-down bearing and withstanding many touch-downs.

In order to solve this problem, Japanese Patent Laid-Open Publication No.
No. 237 discloses that a lead film is formed on a ball rolling surface of an inner ring or an outer ring, and a molybdenum disulfide film is formed on a portion other than the ball rolling surface of an inner ring or an outer ring.

[0007] By using this method, it has become possible to withstand a large number of touchdowns, but this may not be sufficient.

Accordingly, an object of the present invention is to extend the life of a touchdown bearing.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a rotary member supported by a magnetic bearing, in which one of an inner ring and an outer ring is arranged to face each other, and a holding member is provided between the inner ring and the outer ring. In a touch-down bearing of a magnetic bearing device incorporating a ball held by a container, an indium film is formed on at least the surface of the ball.

Since the indium film is formed on the ball surface, the indium of the indium film on the ball surface is transferred to the inner peripheral surface or the outer peripheral surface of the raceway of the inner and outer rings by the rotational motion of the inner and outer rings and the ball, thereby performing a lubricating action. . Furthermore, when the cage is formed of three kinds of lead bronze, if the indium on the ball surface becomes insufficient due to the repetition of friction between the inner and outer rings and the ball, the lead contained in the retainer will cause the lead contained in the cage to become the inner peripheral surface of the inner or outer race or the raceway. It is replenished to the outer peripheral surface to prevent the depletion of the lubricant.

[0011]

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

The touch-down bearing of the magnetic bearing device according to the present invention is a bearing used at the time of touch-down in the magnetic bearing device shown in FIG.

The magnetic bearing device has touch-down bearings 3 and 4 on both ends of a rotating shaft 2 supported in a non-contact manner by a magnetic bearing 1.
If the magnetic bearing 1 becomes uncontrollable due to sudden disconnection or power failure, that is, the rotating shaft 2 is supported by the touchdown bearings 3 and 4 during touchdown, and the magnetic bearing 1 and the rotating shaft 2 are damaged. This has a structure for preventing

As shown in FIG. 2, the touch-down bearing 3 is a front combination of two angular ball bearings 5, 6, which receives both a radial load and an axial load. These angular ball bearings 5 and 6 are
The inner ring 7 faces the rotating member 2 supported by the magnetic bearing 1, is arranged with a touchdown gap, and the outer ring 8 is fixed to the housing 22. And this inner ring 7 and outer ring 8
In between, the ball 10 held by the holder 9 is incorporated and formed.

Further, an indium film 16 is formed on at least the surface of the ball 10 of the touch-down bearing 3. Since it is easy to form the indium film 16 on the surface of the ball 10, the processing steps of the indium film 16 are simplified and the processing time is shortened.

Further, in addition to the surface of the ball 10, an inner or outer peripheral surface of a raceway of the inner ring 7 or the outer ring 8 facing the ball 10, or an end surface connecting the inner and outer peripheral surfaces, An indium film or another solid lubricating film may be formed. By forming a solid lubricating film such as an indium film on these, it is possible to solve the problem of lubrication in the inner ring and the outer ring of the touch-down bearing, and at the time of touch-down, the outer circumferential surface (or inner circumferential surface) of the inner ring 7 or the outer ring 8. The sliding of the ball 10 and the inner ring 7 or the outer ring 8 can be promoted by the solid lubricating film such as an indium film provided on the (surface), so that the rotation of the inner ring 7 and the outer ring 8 can be performed slowly. Therefore, the durability of the touch-down bearing is improved, and the touch-down bearing is less likely to be damaged.

As shown in FIG. 4, a single row deep groove ball bearing is used as the touchdown bearing 4. In this deep groove ball bearing, the inner ring 7 ′ is opposed to the rotating member 2 supported by the magnetic bearing 1, a touchdown gap is provided, and the outer ring 8 ′ is fixed to the housing 22. And
A ball 10 'held by a retainer 9' is incorporated between the inner ring 7 'and the outer ring 8'.

Further, an indium film 16 is formed on at least the surface of the ball 10 'of the touch-down bearing 4. Since it is easy to form the indium film 16 'on the surface of the ball 10', the indium film 16 '
Is simplified, and the processing time is shortened.

Further, in addition to the surface of the ball 10 ', the inner peripheral surface or the outer peripheral surface of the inner ring 7' or the outer ring 8 'facing the ball 10', or the inner peripheral surface and the outer peripheral surface described above. An indium film or other solid lubricating film may be formed on the connecting end surface. By forming a solid lubricating film such as an indium film on these, it is possible to solve the problem of lubrication in the inner ring and the outer ring of the touch-down bearing, and at the time of touch-down, the outer peripheral surface of the inner ring 7 ′ or the outer ring 8 ′ (or A solid lubricating film such as an indium film provided on the (inner peripheral surface) promotes the sliding of the ball 10 'and the inner ring 7' or the outer ring 8 ', so that the inner ring 7' and the outer ring 8 'rotate slowly. be able to. Therefore, the durability of the touch-down bearing is improved, and the touch-down bearing is less likely to be damaged.

As shown in FIG. 3, the retainer 9 is provided with a ball 10 on an annular member 13 formed of a lead-containing copper-based metal.
Are formed by machining. Examples of the lead-containing copper-based metal include lead bronze, for example, three kinds of lead bronze.

The retainer 9 'can be the same as the retainer 9 described above. In addition, as shown in FIG. 5, the annular members 18a and 18 are divided into two in the width direction.
b can be used as one integrally fixed by a rivet 19. At this time, as a material of the retainer 9 ′,
Similarly to the above, there can be mentioned lead-containing copper-based metals, in particular, three types of lead bronze.

In FIGS. 1, 2 and 4, a structure is shown in which the rotating shaft 2 is touched down to the rolling surfaces 12, 12 'of the inner rings 7, 7', but the inner rings 7, 7 'are fixed. However, the present invention can also be applied to a device in which a rotating member is touched down on the rolling surfaces of the outer rings 8, 8 '. In this case, the touch-down bearing used is such that the outer ring faces the rotating member supported by the magnetic bearing, a touch-down gap is provided, and the ball held by the retainer is incorporated between the inner ring and the outer ring. Bearing. An indium film is formed on the ball rolling surface of the outer ring of the bearing or the rolling surface of the outer ring. Also,
The retainer used here can be the same as the retainers 9 and 9 'described above.

The indium films 16, 16 'can be formed by any gas phase method such as an ion plating method. Further, an indium film is formed on the inner peripheral surface or the outer peripheral surface of the raceway of the inner ring 7, 7 'or the outer ring 8, 8' facing the ball 10, 10 ', or on the end surface connecting the inner peripheral surface and the outer peripheral surface. In this case, the indium film can also be formed by an arbitrary gas phase method such as an ion plating method.

The touchdown bearing 3 in the case of FIG.
The operation of No. 4 will be described.

As shown in FIG. 1, in the magnetic bearing device, a rotating shaft 2 is supported by a magnetic bearing 1 in a non-contact manner, and the rotating shaft 2 is rotated. At this time, the contact between the touchdown bearings 3 and 4 and the rotating shaft 2 at both ends is in a non-contact state via the touchdown gap as shown in FIGS. Therefore, the touchdown bearings 3 and 4 are not used in the normal state.

However, when the magnetic bearing 1 is stopped, or when the magnetic bearing 1 becomes uncontrollable due to sudden disconnection, power failure, or the like, a touch-down state occurs. Occurs. At this time, as shown in FIGS. 2 and 4, there is a touchdown gap between the rotating shaft 2 and the touchdown bearings 3 and 4, so that the rotating shaft 2 moves freely within the movable range. In addition, the rotating shaft 2 collides with the inner rings 7, 7 'of the touchdown bearings 3, 4, and the inner rings 7, 7' rotate rapidly. Further, for this reason, the impact load and the sudden acceleration are repeatedly generated in the touchdown bearings 3 and 4.

At this time, since the indium films 16 and 16 ′ are formed on the surface of the ball 10, the rotation of the inner rings 7 and 7 ′ and the ball 10 causes the orbit of the inner ring 7 and 7 ′ of the indium film on the ball surface 15. Transfer to the outer peripheral surface of the ring,
Performs lubrication. Thereby, the impact can be absorbed.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments.

(Embodiment 1) Angular contact ball bearing (F-SF)
863 (608 angular type)) on the ball surface
The indium film was formed by the ion plating method under the conditions shown in (1). Then, an angular contact ball bearing was manufactured using the inner ring and the outer ring.

Using these two bearings, a thrust load of 8
The durability life was measured using a high vacuum bearing life tester under the conditions of 3.4 N and a rotation speed of 2500 rpm. Table 2 shows the results. The life was determined when the sum of the friction torques of the two bearings reached 1 × 10 ⁻² N.

Comparative Example 1 A lead coating was formed on the ball rolling surfaces of the inner and outer rings of the angular contact ball bearing described in Example 1 by an ion plating method under the conditions shown in Table 1. Using this, an angular contact ball bearing was manufactured, and Example 1 was used.
The durability life was measured by the method described in (1). Table 2 shows the results.

Comparative Example 2 A lead coating was formed on the rolling surfaces of the inner ring and the outer ring of the angular ball bearing described in Example 1 by an ion plating method under the conditions shown in Table 1. Using this, an angular contact ball bearing was produced, and the durability life was measured by the method described in Example 1. Table 2 shows the results.

Comparative Example 3 A molybdenum disulfide film was formed on the ball rolling surfaces of the inner ring and outer ring of the angular ball bearing described in Example 1 by magnetron sputtering under the conditions shown in Table 1, and the inner ring and the inner ring A lead film was formed on the rolling surface of the outer ring by the ion plating method shown in Table 1. Using this, an angular contact ball bearing was produced, and the durability life was measured by the method described in Example 1. Table 2 shows the results.

[0034]

[Table 1]

[0035]

[Table 2]

As a result, the bearing provided with the indium film had a longer durability life than other bearings. The lead film and the molybdenum disulfide film tended to increase in torque immediately after the film was worn and tended to stop.

[0037]

According to the present invention, since the indium film is used, the transfer of the lubricating film can be performed smoothly, and the lubricating performance can be maintained for a longer period. For this reason, the life of the touchdown bearing can be made longer.

Further, since the indium film is formed on the ball surface, the processing steps are simplified and the processing time is shortened.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a magnetic bearing device.

FIG. 2 is a sectional view showing an example of a touch-down bearing.

FIG. 3 is a perspective view showing a part of the retainer according to the first embodiment;

FIG. 4 is a sectional view showing another example of the touch-down bearing.

FIG. 5 is a perspective view showing a part of the retainer of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic bearing 2 Rotating shaft 3 Touch-down bearing 4 Touch-down bearing 5 Angular ball bearing 6 Angular ball bearing 7, 7 'Inner ring 8, 8' Outer ring 9, 9 'Cage 10, 10' Ball 12 Rolling surface 13 Ring member 14 pocket hole 16, 16 'indium coating 18a, 18b annular member 19 rivet

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3J101 AA02 AA32 AA42 AA54 AA62 AA82 BA10 BA50 DA05 EA13 EA22 EA23 FA32 3J102 AA01 BA03 BA19 CA14 DA02 DA03 DA09 DB10 DB11 FA12 FA30 5H607 AA01 BB01 DD03 GG01 GG02GG04 GG01 GG02GG04

Claims (2)

[Claims] 1. A touch-down bearing for a magnetic bearing device in which one of an inner ring and an outer ring is opposed to a rotating member supported by a magnetic bearing, and a ball held by a retainer is incorporated between the inner ring and the outer ring. 5. The touchdown bearing for a magnetic bearing device according to claim 1, wherein an indium film is formed on at least the surface of the ball. 2. The touch-down bearing according to claim 1, wherein the cage is formed of three kinds of lead bronze.