JP2002147468A - Insulation bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation bearing solving a problem that a heat radiation property of a bearing becomes bad, temperature of the bearing is raised and a life of the bearing is shortened by early deterioration of grease in an insulation bearing in which an outer periphery of an outer ring is, for example, covered with an insulation coating film made of a synthetic resin in order to prevent an electrolytic corrosion. SOLUTION: A polyester resin is used for an insulation coating film 9 covering an outer periphery 2 of an outer ring 2. The polyester resin can contain an insulation material of 85 wt.% or more having a high heat conductivity and the insulation coating film 9 can exhibit high heat conductivity and insulation property. Ceramics, mica, aluminum hydroxide, etc., are used as an insulation material having a high heat conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated bearing used for, for example, an electric motor for a railway vehicle.

[0002]

2. Description of the Related Art
In bearings used for electric motors for railway vehicles, there is a problem that leakage current from a housing or a shaft flows between a rolling element of the bearing and a bearing ring to cause electrolytic corrosion. Therefore, in order to cut off current from the outside, it has been attempted to provide an insulating coating made of synthetic resin on a fitting surface between the outer peripheral surface of the outer ring and the housing and a fitting surface between the inner ring and the shaft.

However, the thermal conductivity of a general synthetic resin is about 0.3 to 0.4 W / m · K, which is much lower than, for example, the thermal conductivity of iron of 40 W / m · K. By the way, with the recent increase in speed of railway vehicles, the amount of heat generated by bearings during shaft rotation tends to increase. If a synthetic resin with poor thermal conductivity as described above is used for the insulating coating, the heat generated in the bearings will not easily escape to the outside. descend.

[0004] The present invention has been made in view of the above problems, and has as its object to provide an insulated bearing having an insulating film capable of achieving high thermal conductivity and insulating properties.

[0005]

In order to achieve the above object, the present invention provides an insulated bearing having at least one of an inner peripheral surface of an inner ring and an outer peripheral surface of an outer ring covered with an insulating coating. It is characterized by comprising an unsaturated polyester resin composition containing an insulating material having a high thermal conductivity of not less than weight%. The unsaturated polyester resin can be molded even when the content of the filler is considerably high and the content of the unsaturated polyester resin is considerably low. By utilizing this property, it is possible to fill an insulating material having a high thermal conductivity of 85% by weight or more. As a result, extremely high thermal conductivity can be ensured. As a result, the heat radiation of the bearing is enhanced, so that the temperature rise of the bearing can be prevented, and the bearing life can be prolonged by preventing the early deterioration of the grease.

As the insulating film, a film exhibiting high thermal conductivity of, for example, 3 W / m · K or more and high insulating property of, for example, specific resistance of 1 × 10 ¹³ Ω · cm or more is preferable. As the insulating material having high thermal conductivity, for example, ceramic, mica, and aluminum hydroxide are preferable. 8 of these materials
By containing 5% by weight or more, 3 to
This is preferable in that a high thermal conductivity of 5 W / m · K can be exhibited.

In particular, the insulating material having a high thermal conductivity preferably includes a plurality of insulating materials having different particle sizes. For example, when a combination of alumina having a particle size of 1 μm and alumina having a particle size of 5 μm is used, the same weight% is blended as compared with a case where only Alnami having a particle size of 1 μm is used or a case where only alumina having a particle size of 5 μm is used. With such a condition, the thermal conductivity as a whole can be increased. The reason is that when alumina having different particle diameters is dispersed, alumina having a small particle diameter enters between aluminas having a large particle diameter. This is because the distance between the surfaces can be reduced.

Incidentally, since the particle size actually varies, the above-mentioned particle size substantially corresponds to the average particle size. That is, the particle group having an average particle diameter x ₁ μm includes a plurality of particles whose particle diameter x (μm) is in the range represented by x ₁ −a ≦ x ≦ x ₁ + a. Where a
Is about several μm. Therefore, the particles having different particle diameters x ₁ and x _{2 referred} to herein include a first particle group having a particle diameter x in a range of x ₁ −a ≦ x ≦ x ₁ + a and a first particle group having a particle diameter x. A second particle group having a particle size x in a range of x ₂ −a ≦ x ≦ x ₂ + a, which is not included in the particle size range. For example, as in the case of particles having an average particle diameter of 1 μm consisting of a group of particles having a particle size of about 0 to 2 μm and particles having an average particle diameter of 5 μm consisting of a group of particles having a particle size of about 4 to 6 μm, That is, the ranges of variation centered on the average particle size of the particle group do not overlap each other.

Further, the plurality of insulating materials may be of the same type or different types. Preferably, the unsaturated polyester resin is filled with 10% by weight or less of glass fiber. This is because, from the viewpoint of reinforcement, it is preferable to contain as much glass fiber as possible, but if the amount of the unsaturated polyester resin as the base resin is too small, the moldability is deteriorated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view of an insulated bearing according to one embodiment of the present invention. Referring to FIG. 1, the insulating bearing includes an inner ring 1, an outer ring 2, a plurality of rolling elements 3 rotatably interposed between inner and outer rings 1, 2, and a retainer 4 for holding these rolling elements 3. And Two circumferential grooves 5, 6 are formed on the outer peripheral surface 2a of the outer race 2,
Stepped portions 7 and 8 are formed on both end surfaces 2 b of the outer race 2.

The outer ring 2 is covered with an insulating coating 9 over the outer peripheral surface 2a and both end surfaces 2b. Insulation coating 9
Has a cylindrical main body 9a that covers the outer peripheral surface 2a of the outer race 2, and an annular end surface 9b that extends radially inward from both ends of the main body 9a. A pair of annular projections 10 and 11 are formed on the inner periphery of the main body 9 a of the insulating coating 9. The annular projections 10 and 11 are fitted into the corresponding circumferential grooves 5 and 6 to prevent the insulating coating 9 from shifting in the axial direction.

An annular edge 12 extending inward in the axial direction of the insulating coating 9 is provided on the inner periphery of each end face 9 b of the insulating coating 9.
Are formed. Each edge 12 corresponds to the stepped portion 7,
By being fitted to the insulating film 8, the insulating film 9 is prevented from peeling from the end. The insulating coating 9 is made of an unsaturated polyester resin composition containing an insulating material having a high thermal conductivity of 85% by weight or more. The unsaturated polyester resin can be molded even when the content of the filler is considerably high and the content of the unsaturated polyester resin is considerably low. By utilizing this property, it is possible to fill an insulating material having a high thermal conductivity of 85% by weight or more. As shown in FIG. 2, in the case of an insulating material having a high thermal conductivity, 85 wt%
With the vicinity of the critical point as a critical point, the thermal conductivity rapidly increases. Therefore, by filling 85% by weight or more, very high thermal conductivity can be secured as the insulating coating 9. As a result, the heat radiation of the bearing is enhanced, so that the temperature rise of the bearing can be prevented, and the bearing life can be prolonged by preventing the early deterioration of the grease.

It is preferable that the insulating film 9 exhibit high thermal conductivity of, for example, 3 W / m · K or more and high insulating property of, for example, specific resistance of 1 × 10 ¹³ Ω · cm or more. As the insulating material, for example, ceramic, mica, aluminum hydroxide and the like are preferable. In these materials, the insulating coating 9
The thermal conductivity of a general synthetic resin is 0.3 to 0.1.
3 to 5 W / m · K, about 10 times that of 4 W / m · K
K is preferable in that it can exhibit a high thermal conductivity.

The ceramic may be any one that satisfies the above-mentioned high thermal conductivity, and examples thereof include aluminum nitride (AlN), alumina (Al ₂ O ₃ ), magnesium oxide (MgO), and boron nitride (BN). is there. These may be used alone or in combination. this house,
AlN is particularly preferred because of its remarkably high thermal conductivity.
Aluminum hydroxide has a volume resistivity of 8.7 × 10 ¹³
Ω · cm, the thermal conductivity is 0.71 W / m · K, and it has very high insulation and thermal conductivity.

It is preferable that the above-mentioned insulating material having high thermal conductivity contains at least two kinds of insulating materials having different particle sizes. For example, when a ceramic fine powder (for example, alumina) having a particle size of 1 μm and a ceramic fine powder (for example, alumina) having a particle size of 5 μm are used in combination, only the ceramic fine powder having a particle size of 1 μm is used, Compared with the case of using only the same, the thermal conductivity as a whole can be increased even under the condition that they are blended at the same weight%. The reason is that when ceramic fine powders having different particle diameters are dispersed, ceramic fine powders having a small particle diameter enter between ceramic fine powders having a large particle diameter, and only when ceramic fine powders having the same diameter are dispersed. This is because the distance between the surfaces of adjacent ceramic fine powders can be made smaller in comparison.

Since the particle size actually varies, the above-mentioned particle size substantially corresponds to the average particle size. Therefore, that the particle diameters are different means that the average particle diameters are different and the ranges of the variation around each average particle diameter do not overlap. The plurality of insulating materials having different particle sizes may be the same or different. Preferably, the unsaturated polyester resin is filled with 10% by weight or less of glass fiber. This is because, from the viewpoint of reinforcement, it is preferable to contain as much glass fiber as possible, but if the amount of the unsaturated polyester resin as the base resin is too small, the moldability is deteriorated.

The content of the unsaturated polyester resin as the base resin may be less than 15% by weight.
In consideration of moldability, it is more preferably in the range of 10 to 15% by weight. In this case, if glass fibers are contained, the content is 0 to 5% by weight. As described above, according to the present embodiment, a characteristic unsaturated polyester resin capable of including a large amount of filler is used as the base resin of the insulating coating 9. By including 85% by weight or more of an insulating material having high thermal conductivity in the unsaturated polyester resin, the insulating coating 9 can have both high thermal conductivity and insulating properties. By exhibiting the insulating property, the occurrence of electrolytic corrosion can be prevented, and the heat dissipation of the bearing can be improved by the high thermal conductivity, so that the life of the bearing can be extended.

The present invention is not limited to the above embodiment. For example, the insulating coating may be provided on at least one of the outer peripheral surface of the outer race and the inner peripheral surface of the inner race. In addition, various changes can be made within the scope of the present invention.

[Brief description of the drawings]

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

FIG. 2 is a graph showing a relationship between a filling amount of an insulating material having high thermal conductivity and thermal conductivity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Rolling element 4 Cage 5, 6 Circular groove 7, 8 Stepped part 9 Insulation coating

Claims (4)

[Claims] 1. An insulating bearing in which at least one of an inner peripheral surface of an inner ring and an outer peripheral surface of an outer ring is coated with an insulating coating, the insulating coating contains an insulating material having a high thermal conductivity of 85% by weight or more. An insulated bearing comprising a polyester resin composition. 2. The insulated bearing according to claim 1, wherein said insulating material having high thermal conductivity is selected from at least one of ceramic, mica, and aluminum hydroxide. 3. The insulated bearing according to claim 1, wherein the insulating material having high thermal conductivity includes a plurality of insulating materials having different particle sizes. 4. The insulated bearing according to claim 1, wherein the unsaturated polyester resin is filled with 10% by weight or less of glass fiber.