JP2016158314A - Bearing of rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent damage when a dielectric plane is pushed into the outer periphery of a bearing box and fitted therein during manufacturing of a bearing.SOLUTION: The bearing of a rotary electric machine includes a bearing metal 2 for supporting a revolving shaft 3 by an inner peripheral surface 14a via an oil film and a bearing box 1 for supporting the outer peripheral surface 13a of the bearing metal 2. By using the bearing of the rotary electric machine in which the layer of a dielectric plate 5 is disposed between the inner peripheral surface 14a and the outer peripheral surface 13a of the bearing metal 2 so as to electrically separate them, it becomes possible to prevent damage when the dielectric plane is pushed into the outer periphery of the bearing box and fitted therein during manufacturing of the bearing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bearing for a rotating electrical machine such as a generator.

  In a rotating electrical machine such as a generator, both ends of a rotating shaft are supported by bearings. The bearing is composed of a bearing metal formed of an annular shape or a plurality of arc-shaped pieces that support the rotating shaft on the inner side through an oil film, and a hollow bearing box that supports the bearing metal on the inner side.

  A lubrication facility is provided outside the bearing, and the lubrication oil is supplied to and discharged from the clearance between the inner peripheral surface (hereinafter referred to as the bearing surface) of the bearing that supports the rotating shaft and the rotating shaft. Thus, the oil film is formed.

  In a large rotating electrical machine, a rotating shaft that is supported only at both ends by a bearing bends due to gravity, and therefore, a shape in which a surface supported by a bearing box of a bearing metal is a convex spherical shape is often employed. (See Patent Document 1 below).

  Further, when the magnetic resistance of the rotating shaft is not uniform in the circumferential direction, an electromotive force is generated by an alternating magnetic field on the rotating rotating shaft. This electromotive force has a magnitude of about several volts, and an oil film is formed in the gap between the bearing surface and the rotating shaft as described above. Therefore, normally, no current flows from the rotating shaft to the bearing.

  However, when the oil film is not sufficiently formed due to factors such as insufficient supply amount of the lubricating oil, there arises a problem that current flows due to contact between the rotating shaft and the bearing surface.

  In order to prevent this problem, for example, in the rotating electrical machine disclosed in Patent Document 1 below, by providing an annular insulating plate along the outer peripheral surface of the bearing box, it is possible to prevent leakage to a structure outside the bearing box. It is out. Generally, epoxy resin or fluorine-based resin is used for the insulating plate, and the insulating plate is installed by being pushed into the bearing housing.

  On the other hand, frictional torque is generated by the circumferential shear stress of the oil film acting on the surface of the rotating shaft. The oil film generates heat due to frictional torque, but this amount of heat is discharged to the outside of the bearing by the supply and discharge of the lubricating oil described above, so that a thermal equilibrium state is maintained.

Japanese Patent Laid-Open No. 2003-70204

  Increasing the amount of lubricating oil supplied and discharged increases the amount of heat discharged to the outside of the bearing. However, recently, it has been required to reduce the production cost by downsizing the oil supply equipment or using a self-oil supply system that pumps up the lubricating oil with an oil ring or oil disk without supplying the oil supply equipment and supplies the lubricating oil. If these means are used, the amount of lubricating oil supplied and the amount of oil discharged will decrease, and the amount of heat discharged outside the bearing will decrease.

  In order to maintain the thermal equilibrium state even if the oil supply amount and the oil discharge amount are reduced, it is necessary to increase the thermal conductivity from the bearing to the external structure. However, the epoxy resin or fluorine-based resin constituting the insulating plate along the outer periphery of the bearing box has a problem that the thermal conductivity is small.

  On the other hand, since the insulating plate receives the load of the rotor and the vibration load due to the operation during operation, there are cases where the insulation plate is damaged by long-term use.

  The present invention has been made in view of the above-described technical situation, and is a bearing for a rotating electrical machine that can increase the thermal conductivity of the bearing and prevent damage to the insulating plate during manufacturing. The purpose is to provide.

A bearing for a rotating electrical machine according to a first invention for solving the above-described problems is
A bearing metal that supports a rotating shaft by an inner peripheral surface through an oil film, and a bearing of a rotating electrical machine that includes a bearing box that supports the outer peripheral surface of the bearing metal,
An insulating plate layer is disposed between the inner peripheral surface and the outer peripheral surface so as to electrically separate the inner peripheral surface and the outer peripheral surface of the bearing metal.

A bearing for a rotating electrical machine according to a second invention that solves the above-described problem is as follows.
In the rotary electric machine bearing according to the first invention,
The bearing metal includes an inner support portion having the inner peripheral surface, and an outer support portion having an outer peripheral surface disposed on the radially outer side of the inner support portion,
The insulating plate may be disposed between the inner support portion and the outer support portion.

A bearing for a rotating electrical machine according to a third aspect of the present invention for solving the above-described problem is
In the rotary electric machine bearing according to the first or second invention,
The outer peripheral surface of the bearing metal has a convex spherical shape, and the surface of the bearing box that supports the outer peripheral surface has a concave spherical shape corresponding to the convex spherical shape.

A bearing for a rotating electrical machine according to a fourth invention for solving the above-described problems is
In the rotating electrical machine bearing according to any one of the first to third aspects of the invention,
The insulating plate is made of alumina.

  According to the bearing of the rotating electrical machine according to the first aspect of the invention, insulation is provided between the inner peripheral surface and the outer peripheral surface so as to electrically separate the inner peripheral surface and the outer peripheral surface of the bearing metal. Since the layers of the plate are arranged, the insulating plate has a higher strength due to a smaller diameter than the conventional insulating plate arranged on the outer periphery of the bearing metal. Damage can be prevented.

  According to the bearing of the rotating electrical machine according to the second aspect of the invention, in the bearing of the rotating electrical machine according to the first aspect of the invention, the bearing metal includes an inner support portion having the inner peripheral surface, and the inner support portion. An outer support portion having an outer peripheral surface is provided on the outer side in the radial direction, and the insulating plate is arranged between the inner support portion and the outer support portion. Since the strength is increased by reducing the diameter as compared with the conventional insulating plate disposed on the outer periphery of the insulating plate, it is possible to prevent the insulating plate from being damaged during manufacture.

  According to the bearing of the rotating electrical machine according to the third aspect of the invention, in the bearing of the rotating electrical machine according to the first or second aspect of the invention, the outer peripheral surface of the bearing metal has a convex spherical shape and supports the outer peripheral surface. Since the surface of the bearing box has a concave spherical shape corresponding to the convex spherical shape, it can be applied to a spherical bearing provided in a large rotating electrical machine.

  According to the bearing of the rotating electrical machine according to the fourth aspect of the invention, in the rotating electrical machine bearing according to any one of the first to third aspects of the invention, the insulating plate is made of alumina. Compared with a conventional bearing using a fluorine-based resin, the thermal conductivity can be increased and the strength can be increased, and the long-term reliability during operation can be improved.

It is sectional drawing explaining the bearing of the rotary electric machine which concerns on Example 1 of this invention. It is sectional drawing explaining the bearing of the rotary electric machine which concerns on Example 2 of this invention. It is sectional drawing explaining the bearing of the rotary electric machine which concerns on Example 3 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, bearings of a rotating electrical machine according to the present invention will be described with reference to the drawings in the embodiments.

[Example 1]
A bearing of a rotating electrical machine according to a first embodiment of the present invention will be described with reference to FIG.

  The bearing of the rotating electrical machine according to the first embodiment of the present invention includes a bearing metal 2 formed of an annular or a plurality of arc-shaped pieces that support the rotating shaft 3 on the inside via an oil film (not shown) of lubricating oil, and A hollow bearing box 1 is provided which supports the bearing metal 2 on the inner side and is supported by the outer peripheral surface 1 a contacting the base 4.

  The bearing metal 2 is arranged on the radially outer side of the inner support portion 14 and the inner support portion 14, each of which has an inner circumferential surface 14 a as a bearing surface that supports the rotating shaft 3, and is composed of an annular or a plurality of arc-shaped pieces. The outer support portion 13 is formed of an annular shape or a plurality of arc-shaped pieces having a convex spherical outer peripheral surface 13a. In the example shown in FIG. 1, the outer support portion 13 is shorter than the inner support portion 14 in the axial direction.

  The bearing box 1 has a bearing metal support portion 11 having a support surface 11a for supporting the outer peripheral surface 13a of the bearing metal 2 and extends toward the rotary shaft 3 at both ends in the axial direction to adjust the amount of lubricating oil discharged. An oil draining portion 12 is formed. The support surface 11 a of the bearing housing 1 has a concave spherical shape corresponding to the convex spherical shape of the outer peripheral surface 13 a of the bearing metal 2.

  As described above, the bearing surface 1a of the bearing housing 1 has a concave spherical shape, and the outer peripheral surface 13a of the bearing metal 2 has a convex spherical shape, so that the bearing of the rotating electrical machine according to the first embodiment of the present invention has a spherical seat, It can be used for large rotating electrical machines.

  Between the inner side support part 14 and the outer side support part 13, the insulating board 5 is provided over the whole circumferential direction. This configuration is produced by pressing the insulating plate 5 into the inner support portion 14 and then fitting the outer support portion 13 into the insulating plate 5.

  By configuring as described above, the insulating plate 5 is provided between the inner peripheral surface 14a and the outer peripheral surface 13a of the bearing metal 2 so as to electrically separate the inner peripheral surface 14a and the outer peripheral surface 13a of the bearing metal 2. Thus, the diameter of the insulator 5 is smaller than that of a conventional insulating plate disposed on the outer periphery of the bearing metal 2. In general, since an annular or arcuate structure has a high strength due to a small diameter, it is possible to prevent damage when the insulating plate 5 is fitted into the inner support portion 14 during manufacturing.

  The material of the insulating plate 5 is alumina instead of the conventional epoxy resin or fluorine resin. Hereinafter, the properties of an epoxy resin glass laminate and alumina will be compared as an example. The following EL-GEH, EL-GEF, and A-479 are notations based on the JIS standard.

Regarding the insulation resistance, the epoxy resin glass laminate (EL-GEH) is 10 ⁶ to 10 ⁷ [MΩ], whereas the alumina (A-479) is 10 ⁸ [MΩ] or more.

  Regarding the thermal conductivity (at 20 ° C.), the epoxy resin glass laminate (EL-GEF) is about 0.2 [W / m · K], whereas alumina (A-479) is 29 [W / M · K].

  Regarding the compressive strength, the epoxy resin glass laminate (EL-GEH) has a value of 441 to 539 [MPa], whereas alumina (A-479) has a value of 2160 [MPa].

  Regarding the Young's modulus, the epoxy resin glass laminate (EL-GEH) is 21.6 to 24.5 [GPa], while the alumina (A-479) is 360 [GPa].

  As described above, since alumina has higher thermal conductivity than epoxy resin and fluorine-based resin, the bearing of the rotating electrical machine according to the first embodiment of the present invention that uses alumina for the insulating plate 5 has epoxy on the insulating plate 5. Compared to conventional bearings using resin or fluororesin, the thermal conductivity to the outside of the bearing is increased, and the thermal equilibrium state is maintained even if the amount of lubricating oil supplied to the bearing and the amount of oil drained are reduced. Can do.

  In addition, since alumina has higher compressive strength and Young's modulus than epoxy resin and fluororesin, the bearing of the rotating electrical machine according to the first embodiment of the present invention using alumina for the insulating plate 5 has epoxy on the insulating plate 5. Compared with a conventional bearing using resin or fluorine resin, the strength is higher, and it is possible to prevent breakage when fitting the insulating plate 5 by pushing it into the inner support portion 14 during manufacturing.

  Further, as in the present embodiment, the axial length of the outer support portion 13 having the outer peripheral surface 13a is made shorter than the inner support portion 14 having the inner peripheral surface 14a, and the insulating plate 5 is provided therebetween. By doing so, the axial length of the insulating plate 5 can be shortened, which is advantageous in terms of manufacturing and cost.

[Example 2]
A bearing of a rotating electrical machine according to a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, the same components as those in the first embodiment are denoted by the same reference numerals. In the following, description will be made centering on differences from the first embodiment.

  The bearing metal 6 is formed of an annular shape or a plurality of arc-shaped pieces, and is a convex surface supported by an inner peripheral surface 6 b as a bearing surface for supporting the rotating shaft 3 and a concave spherical support surface 11 a of the bearing box 1. A spherical outer peripheral surface 6a is provided. FIG. 2 shows an example in which the inner peripheral surface 6b is longer in the axial direction than the outer peripheral surface 6a.

  That is, the bearing metal 6 of the present embodiment is not divided into the inner support portion 14 and the outer support portion 13 like the bearing metal 2 of the first embodiment, and is an integral one.

  An insulating plate 7 is disposed on a portion of the outer peripheral surface 1 a of the bearing housing 1 that is in contact with the base 4 and other structures not shown. The material of the insulating plate 7 is alumina instead of the conventional epoxy resin or fluorine resin.

  Similar to the description in the first embodiment, alumina has a higher thermal conductivity than the epoxy resin and the fluorine-based resin. Therefore, the bearing of the rotating electrical machine according to the first embodiment of the present invention using alumina for the insulating plate 7 is the insulating plate 7. Compared to conventional bearings that use epoxy resin or fluororesin, the thermal conductivity to the outside of the bearing increases, and the thermal equilibrium state is maintained even if the amount of lubricating oil supplied to the bearing and the amount of oil drained are reduced. Will be able to keep.

  In addition, since alumina has higher compressive strength and Young's modulus than epoxy resin and fluororesin, the bearing of the rotating electrical machine according to the first embodiment of the present invention using alumina for the insulating plate 7 has epoxy on the insulating plate 7. Compared to a conventional bearing using resin or fluorine resin, the strength is higher, and it is possible to prevent breakage when the insulating plate 7 is fitted into the bearing metal 6 during manufacturing.

[Example 3]
A bearing for a rotating electrical machine according to a third embodiment of the present invention will be described with reference to FIG. In FIG. 3, the same components as those in the first and second embodiments are denoted by the same reference numerals. Below, it demonstrates centering on a different part from Example 1,2.

  The bearing of the rotating electrical machine according to the third embodiment of the present invention is a rolling bearing, and is supported on the inner ring 23 via a plurality of rolling elements 22 and an inner ring 23 fixed to the rotating shaft 3 and rotatable together with the rotating shaft 3. An outer ring 21 and a hollow bearing box 9 that supports the outer ring 21 on the inner side and supports the outer peripheral surface 9 a in contact with the base 4 are provided.

  An insulating plate 8 is disposed on a portion of the outer peripheral surface 9a of the bearing housing 9 that is in contact with the base 4 and other structures not shown. The material of the insulating plate 8 is alumina instead of the conventional epoxy resin or fluorine resin.

  That is, although the bearing of the rotary electric machine which concerns on Example 1, 2 of this invention shall be a sliding bearing, the bearing of the rotary electric machine which concerns on Example 3 of this invention is a rolling bearing. Even in such a case, by using alumina for the insulating plate 8, the thermal conductivity to the outside of the bearing increases, and even if the amount of lubricating oil supplied to the bearing and the amount of drained oil decrease, the thermal equilibrium state is maintained. It can be maintained, and the strength is high, so that it is possible to prevent breakage when the insulating plate 8 is fitted into the bearing box 9 during manufacture.

  The present invention is suitable as a bearing for a rotating electrical machine such as a generator.

DESCRIPTION OF SYMBOLS 1,9 Bearing case 2,6 Bearing metal 3 Rotating shaft 4 Base 5, 7, 8 Insulating plate 1a Outer peripheral surface 6a (of bearing housing 1) Outer peripheral surface 6b (Inside of bearing metal 6) 9a Peripheral surface 11 (of bearing housing 9) Bearing metal support portion 11a (Support surface of bearing metal support portion 12) 12 Oil drain portion 13 Outer support portion 13a (Outside support portion 13) Outer peripheral surface 14 Inner support portion 14a (Inner side) Inner peripheral surface 21 of support portion 14 outer ring 22 rolling element 23 inner ring

Claims (4)

A bearing metal that supports a rotating shaft by an inner peripheral surface through an oil film, and a bearing of a rotating electrical machine that includes a bearing box that supports the outer peripheral surface of the bearing metal,
Insulating plate layer is disposed between the inner peripheral surface and the outer peripheral surface so as to electrically separate the inner peripheral surface and the outer peripheral surface of the bearing metal. Bearings. The bearing metal includes an inner support portion having the inner peripheral surface, and an outer support portion having the outer peripheral surface arranged on the radially outer side of the inner support portion,
The bearing for a rotating electrical machine according to claim 1, wherein the insulating plate is disposed between the inner support portion and the outer support portion. The outer peripheral surface of the bearing metal has a convex spherical shape, and the surface of the bearing box that supports the outer peripheral surface has a concave spherical shape corresponding to the convex spherical shape. The bearing of the rotary electric machine described. The bearing of the rotating electrical machine according to any one of claims 1 to 3, wherein the insulating plate is made of alumina.

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