WO2022045190A1

WO2022045190A1 - Insulating rolling bearing

Info

Publication number: WO2022045190A1
Application number: PCT/JP2021/031148
Authority: WO
Inventors: 章央松本; 裕田中
Original assignee: Ntn株式会社
Priority date: 2020-08-26
Filing date: 2021-08-25
Publication date: 2022-03-03
Also published as: JP2022038349A; CN115885113A

Abstract

Provided is an insulating rolling bearing that can prevent electrolytic corrosion, and that prevents hugging onto a shaft or the like and the falling out from an inner race or the like. The insulating rolling bearing comprises: an inner race 2 and an outer race which comprise steel; a plurality of rolling elements which are interposed between the inner and outer races; and an insulating bushing 10 which is roughly cylindrical and which is engaged with the inner peripheral surface 2a of the inner race 2. The insulating bushing 10 includes: on the outer diameter side, an insulating part 8 comprising a resin composition; and on the inner diameter side, a metal part 9. The insulating part 8 and the metal part 9 are configured to be separate elements. The metal part 9 is a split bushing in which a joint 9a is formed in one section in the circumferential direction. The insulating part 8 is cylindrical member that covers the joint 9a of the split bushing from the outer diameter side thereof.

Description

Insulated rolling bearing

The present invention relates to an insulated rolling bearing.

For example, an insulated rolling bearing that insulates and supports a rotating shaft through which an electric current may flow, such as a rotating shaft of an electric motor or a rotating shaft of a refrigerant compressor, is known. By using an insulated rolling bearing, it is possible to prevent electrolytic corrosion from occurring on both the inner and outer raceway surfaces of the rolling bearing and the rolling surface of the rolling element.

For example, in the refrigerant compressor described in Patent Document 1, a resin sleeve made of a resin material is used between the crank shaft and the sub bearing that rotationally supports the sub shaft portion on the anti-compression mechanism portion side of the drive portion in the crank shaft. Is provided. As a result, the reliability of the refrigerant compressor is improved by suppressing bearing damage due to electrolytic corrosion with an inexpensive structure without using a rolling bearing filled with conductive grease.

Japanese Unexamined Patent Publication No. 2018-40261

In the refrigerant compressor described in Patent Document 1, a resin sleeve is fitted to the inner peripheral surface of the inner ring by means such as press fitting. However, under the conditions of use in an actual machine where heating and cooling are repeated, there is a concern that the resin sleeve may cling to the crank shaft or the resin sleeve may come off from the inner ring. Further, it is conceivable to fit a similar resin sleeve on the outer peripheral surface of the outer ring to improve insulation, but there is a concern that the resin sleeve may cling to the outer ring or the resin sleeve may come off from the housing. ..

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an insulated rolling bearing that can prevent electrolytic corrosion, hug to a shaft or the like, or fall off from an inner ring or the like.

The insulated rolling bearing of the present invention has a substantially cylindrical shape fitted to an inner ring and an outer ring made of a steel material, a plurality of rolling elements interposed between the inner and outer rings, and an inner peripheral surface of the inner ring or an outer peripheral surface of the outer ring. The insulating rolling bearing provided with the insulating bush of the above, characterized in that the insulating bush has an insulating portion made of a resin composition on the outer diameter side and a metal portion on the inner diameter side.

The feature is that the insulating part and the metal part are formed separately. Further, the metal portion is a split bush in which a mating opening is formed in a part in the circumferential direction, and the insulating portion is a cylindrical member that covers the mating opening of the split bush from the outer diameter side. ..

The outer peripheral surface of the insulating portion is characterized by having a tapered shape whose diameter increases from one side in the axial direction toward the other side.

The base resin of the resin composition of the insulating portion is a polyphenylene sulfide (PPS) resin, a polyether ketone (PEK) -based resin, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, or a tetrafluoroethylene-hexa. It is characterized by being a fluoropropylene copolymer (FEP) resin or a tetrafluoroethylene-ethylene copolymer (ETFE) resin.

The metal part is characterized by being carbon steel or stainless steel for machine structure.

The insulated rolling bearing of the present invention includes a substantially cylindrical insulating bush fitted to the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring, and the insulating bush has an insulating portion made of a resin composition on the outer diameter side. Since it has a metal part on the inner diameter side, for example, when fitting to the inner diameter of the inner ring, a resin insulating part is arranged on the side in contact with the inner peripheral surface of the inner ring, and the metal part is arranged on the side in contact with the shaft. As a result, electrolytic corrosion can be prevented without metal contact between the shaft and the inner ring. Further, since the resin insulating portion does not come into contact with the shaft, it is possible to prevent the insulating portion from sticking to the shaft.

In addition, the inner ring is made of steel such as bearing steel, and its linear expansion coefficient is smaller than that of resin material. Therefore, on the high temperature side of the usage environment range, the insulating portion is in the direction along the inner peripheral surface of the inner ring. On the other hand, on the low temperature side of the usage environment range, the insulating portion may shrink, but the metal portion on the inner diameter side supports the insulating portion from the inside, so that the shrinkage of the resin is suppressed. This makes it possible to prevent the insulating bush from falling off from the inner ring even under the condition that heating and cooling are repeated.

Further, even when the insulating bush is fitted to the outer diameter of the outer ring, the resin insulating portion and the outer ring do not come into contact with each other, so that it is possible to prevent electrolytic corrosion while preventing the insulating portion from sticking to the outer ring. .. Further, on the high temperature side of the usage environment range, the insulating portion is in the direction along the inner peripheral surface of the housing. On the other hand, on the low temperature side of the usage environment range, the insulating portion may shrink, but the metal portion on the inner diameter side supports the insulating portion from the inside, so that the shrinkage of the resin is suppressed. This makes it possible to prevent the insulating bush from falling off from the housing even under conditions where heating and cooling are repeated.

Since the insulating part and the metal part are composed separately, the degree of freedom in the shape of the insulating part and the metal part can be improved as compared with the case where the insulating part and the metal part are integrally configured. Further, the metal portion is a split bush in which an abutment is formed in a part in the circumferential direction, and the insulating portion is an annular member that covers the abutment of the metal portion from the outer diameter side, so that the abutment is formed. As a result, the metal portion can be provided with a spring force that spreads in the radial direction, and the shrinkage of the insulating portion can be preferably suppressed. In addition, by covering the abutment with an insulating portion, electrolytic corrosion can be reliably prevented.

Since the outer peripheral surface of the insulating portion has a tapered shape that expands in diameter from one side in the axial direction to the other side, for example, it is easy to manage the fit between the inner ring and the insulating portion, and the cost is reduced. Can be done.

Since the base resin of the resin composition of the insulating part is PPS resin, PEK resin, PFA resin, FEP resin, or ETFE resin, it is excellent in heat resistance and chemical resistance.

It is an enlarged sectional view of the insulation rolling bearing of this invention. It is an exploded perspective view of the insulation bush of FIG. It is an exploded perspective view which shows other form of an insulation bush. It is an exploded perspective view which shows other form of an insulation bush. It is sectional drawing in the axial direction of the test member of Comparative Examples 1 and 2. It is a figure which shows the outline of the pull-out force test. It is a figure which shows the outline of the energization test. It is a photograph of Comparative Example 1 after the withdrawal force test. It is a graph which compared the manufacturing cost of an Example and a comparative example. It is a graph which compared the manufacturing cost of the formation part of ceramic spraying.

A form of the insulated rolling bearing of the present invention will be described with reference to FIG. As shown in FIG. 1, the insulated rolling bearing 1 has an inner ring 2 and an outer ring 3 which are raceway rings, a bearing main body having a plurality of balls (rolling elements) 4 interposed between the inner and outer rings, and an inner ring 2. It is provided with an insulating bush 10 fitted to the inner peripheral surface of the above. The balls 4 are aligned and held at regular intervals by the cage 5. The bearing space around the ball 4 is filled with grease 7, and the bearing space is sealed by the sealing member 6. The inner ring 2, the outer ring 3, and the ball 4 are made of steel. Examples of the steel material include bearing steel such as SUJ2 used for rolling bearings, carburized steel, carbon steel for machine structure, cold rolled steel, hot rolled steel and the like.

In FIG. 1, the insulating bush 10 has a substantially cylindrical shape, and has an insulating portion 8 made of a resin composition on the outer diameter side and a metal portion 9 on the inner diameter side. In the insulated rolling bearing 1, the bearing main body and the insulating bush 10 are integrated by press-fitting and are not adhered by an adhesive or the like. By inserting the shaft S into the shaft hole of the insulated rolling bearing 1, the shaft S, the insulating bush 10, and the inner ring 2 are integrated. As shown in FIG. 1, by interposing the insulating portion 8 between the shaft S and the inner ring 2, it is possible to block the axial current from flowing to the bearing main body portion via the shaft S.

The insulating bush 10 will be described in detail with reference to FIG. FIG. 2A shows an exploded perspective view of the inner ring and the insulating bush. In FIG. 2A, the insulating portion 8 and the metal portion 9 are formed separately. The insulating portion 8 is a cylindrical member having a predetermined wall thickness, and is a molded body of a resin composition described later. The metal portion 9 is a split bush in which a joint portion 9a is formed in a part in the circumferential direction. In FIG. 2A, the abutment 9a is formed along the axial direction of the metal portion 9. The abutment 9a may be formed from one end to the other end in the axial direction while being inclined at a predetermined angle with respect to the axial direction. The predetermined angle is, for example, 1 ° to 30 °, preferably 1 ° to 10 °.

As for the assembly order of the insulated rolling bearing, first, the insulating portion 8 of the cylindrical member is fitted into the inner peripheral surface 2a of the inner ring 2 with a tightening allowance. After that, the insulating bush is obtained by fitting the metal portion 9 into the inner peripheral surface 8a of the insulating portion 8 while narrowing the abutment 9a and elastically deforming the metal portion 9.

FIG. 2B shows a radial cross-sectional view in a state where the insulating bush is fitted. The metal portion 9 has a spring property that urges the insulating portion 8 in a direction of pressing the insulating portion 8 against the inner peripheral surface 2a of the inner ring 2, and is fixed to the inner peripheral surface 8a of the insulating portion 8 by the spring force. It is preferable that the abutment 9a of the metal portion 9 is formed so as to stably support the shaft while appropriately exerting a spring force that spreads outward in the radial direction. For example, the two separated ends are formed so as to fit within the range of ± θ with respect to the center position of the abutment 9a. In this range, in the metal portion 9, the center position of the abutment 9a (the center position in the circumferential direction between the end faces of each end) is set to 0 ° at the circumferential position, and the central angle is ± θ based on this. Refers to the range. The range of ± θ is preferably a range of ± 10 °, preferably a range of ± 5 °.

As shown in FIG. 2B, the insulating portion 8 covers the abutment 9a of the metal portion 9 from the outer diameter side to ensure the insulating property. Depending on the operating temperature environment, the insulating portion 8 may expand or contract, but the metal portion 9 has a spring property that expands radially outward, and the insulating portion 8 has an inner peripheral surface of the inner ring 2 due to the spring force. Since it is pressed against 2a, expansion and contraction of the insulating portion 8 is suppressed, and the dimensional stability of the inner diameter of the insulating rolling bearing can be maintained. As a result, the shaft can be stably supported regardless of the temperature environment.

The material of the metal part is preferably a molten metal from the viewpoint of strength, and more preferably an iron-based molten metal. As the iron system, carbon steel for general structure (SS400, etc.), carbon steel for machine structure (S45C, etc.), stainless steel (SUS303, SUS316, etc.) and the like can be used. Further, these iron-based materials may be plated with zinc, nickel, copper or the like. The wall thickness of the metal portion is not particularly limited, and is, for example, 0.5 mm to 5 mm, more preferably 1 mm to 3 mm. The split bush of FIG. 2 is obtained by bending a metal plate having a predetermined thickness.

Further, the wall thickness of the insulating portion is not particularly limited, and is, for example, 0.5 mm to 5 mm, more preferably 1 mm to 3 mm. Regarding the wall thickness of the insulating portion and the wall thickness of the metal portion, whichever is thicker or may be about the same thickness.

Examples of the base resin of the resin composition used for the insulating portion include PEK-based resin, polyacetal (POM) resin, PPS resin, injection-moldable thermoplastic polyimide resin, polyamideimide (PAI) resin, and polyamide (PA) resin. Examples thereof include fluororesins that can be injection-molded. These resins may be used alone or as a polymer alloy in which two or more kinds are mixed. Among these resins, PPS resin, PEK resin, PFA resin, FEP resin, and ETFE resin are preferable because they are excellent in chemical resistance and heat resistance. Examples of the PEK-based resin include polyetheretherketone (PEEK) resin, polyetherketone (PEK) resin, and polyetherketone etherketoneketone (PEKEKK) resin.

In addition, additives can be appropriately added to the above base resin as needed. As the additive, since the creep resistance can be improved, for example, a non-conductive reinforcing material such as glass fiber, aramid fiber, potassium titanate whiskers, and titanium oxide whiskers can be blended.

The linear expansion coefficient of the resin composition used for the insulating portion is preferably 1 × ^10-5 / ° C to 10 × ^10-5 / ° C, preferably 1 × ^10-5 / ° C to 5 × ^10-5 / ° C. Is more preferable. Further, the relationship with the linear expansion coefficient of the material of the metal portion is not particularly limited, and for example, it is preferable that the linear expansion coefficient of the material of the insulating portion is larger than the linear expansion coefficient of the material of the metal portion.

The molding method of the insulating part is not particularly limited, and methods such as compression molding, extrusion molding, and injection molding can be adopted. In the case of injection molding, various raw materials are melt-kneaded to form pellets for molding, which are then molded into a predetermined shape by an injection molding method.

FIG. 3 shows another form of the insulating bush according to the present invention. The insulating bush 13 shown in FIG. 3 has a different structure of the insulating portion from the insulating bush 10 of FIG. FIG. 3A is an exploded perspective view of the inner ring and the insulating bush, and FIG. 3B is an axial sectional view of the insulating bush.

In FIG. 3A, the insulating portion 11 and the metal portion 12 are formed separately. The metal portion 12 is a split bush in which a joint portion 12a is formed so as to be separated from a part in the circumferential direction, and has the same configuration as the metal portion 9 in FIG. 2A. On the other hand, as shown in FIG. 3B, the insulating portion 11 has an inner peripheral surface 11a which is a cylindrical surface parallel to the axial direction, and the outer peripheral surface 11b expands in diameter from one side in the axial direction to the other side. It is a tapered surface. The wall thickness of the insulating portion 11 increases from one side in the axial direction toward the other side, and each end portion in the axial direction becomes the thinnest portion and the thickest portion of the wall thickness. The wall thickness difference between the thinnest portion and the thickest portion is, for example, 0.5 mm to 2 mm. In this form, it is preferable that the wall thickness of the insulating portion 11 is thicker than the wall thickness of the metal portion 12, that is, the wall thickness of the thinnest portion of the insulating portion 11 is thicker than the wall thickness of the metal portion 12. ..

As for the assembly order of the insulated rolling bearing, first, the insulating portion 11 of the substantially cylindrical member is fitted into the inner peripheral surface 2a of the inner ring 2. At this time, if the outer peripheral surface 11b of the insulating portion 11 is tapered, it can be fitted into the inner ring 2 even if there is a mutual difference in dimensions. Therefore, as compared with the configuration of FIG. 2, it is possible to easily manage the tightening allowance between the inner diameter of the inner ring 2 and the outer diameter of the insulating portion 11. After that, the insulating bush is obtained by fitting the metal portion 12 into the inner peripheral surface 11a of the insulating portion 11 while elastically deforming the metal portion 12.

FIG. 4 shows yet another form of the insulating bush. FIG. 4 is an exploded perspective view of the inner ring and the insulating bush. As shown in FIG. 4, the insulating bush 16 is a bush in which an insulating portion 14 made of a ceramic sprayed coating is formed on an outer peripheral surface of a cylindrical metal portion 15.

As the base material for ceramics, metal oxides such as alumina, magnesia, zirconia, and titania, silicon nitride, silicon carbide, or a mixture thereof are used. The composition of the sprayed material may be, for example, an alumina content of 95.0 to 98.5% by mass, another metal oxide content of 1.5 to 5.0% by mass, and an alumina content of 97. When the content is 0.0% by mass or more and the content of the metal oxide such as zirconia is 1.5 to 2.5% by mass, the strength and toughness can be improved as well as the insulating property.

As the thermal spraying method, a well-known plasma spraying method such as atmospheric pressure plasma spraying performed in the atmosphere can be adopted. Further, a well-known thermal spraying method such as a powder type frame thermal spraying method or a high-speed gas flame thermal spraying method can also be adopted.

The thickness of the ceramic sprayed coating is preferably 30 μm to 300 μm. If it is less than 30 μm, sufficient insulating properties may not be obtained, and if it exceeds 300 μm, the manufacturing cost tends to increase.

The insulated rolling bearing provided with the insulating bush in the form shown in FIG. 4 is fitted with a metal portion 15 having a ceramic sprayed coating on the outer peripheral surface of the inner peripheral surface 2a of the inner ring 2 with a tightening margin. The tightening allowance is set in consideration of the difference between the material of the inner ring 2 and the linear expansion coefficient of the ceramics. Generally, bearing steel is used for the inner ring, but the linear expansion coefficient is higher than that of ceramics. Therefore, the tightening allowance is set to a value at which the tightening allowance with the outer peripheral surface of the metal portion does not disappear even if the inner ring expands on the high temperature side of the usage environment range. On the other hand, on the low temperature side of the usage environment range, the inner ring 2 shrinks, so that it tends to stick to the metal portion 15. Therefore, it is possible to prevent the insulating bush 16 from falling off from the inner ring 2 even when the thermal impact test is performed. Further, in the case of this configuration, it is not necessary to perform a special surface treatment on the inner peripheral surface of the metal portion 15, and it is not necessary to inject the resin. Further, since the ceramics are sprayed on the outer peripheral surface of the metal portion 15, the cost can be reduced as compared with the case of spraying on the inner peripheral surface. Further, since the shaft does not come into metal contact with the inner ring, the insulating property is maintained and there is an effect of preventing galvanic corrosion.

In addition, in order to have insulation performance, a method of spraying ceramics directly on the inner peripheral surface of the inner ring is conceivable, but the size and shape of the thermal spraying material that can be sprayed on the inner peripheral surface are limited by the balance of the thermal spraying method. Therefore, the cost tends to be high.

The configuration of the insulated rolling bearing of the present invention is not limited to the configurations of FIGS. 1 to 4, for example, although a ball bearing is shown in FIG. 1, the insulated rolling bearing of the present invention is a conical roller bearing, a cylindrical roller bearing, and the like. It can also be applied to self-aligning roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust conical roller bearings, thrust needle roller bearings, thrust self-aligning roller bearings, and the like.

The insulating rolling bearings shown in FIGS. 1 to 4 have a structure in which an insulating bush is fitted to the inner peripheral surface of the inner ring, but the present invention is not limited to this. For example, the bearing may be obtained by fitting an insulating bush 10 (see FIG. 2), an insulating bush 13 (see FIG. 3), an insulating bush 16 (see FIG. 4), or the like on the outer peripheral surface of the outer ring. In the mounted state, the metal portion of the insulating bush is fitted so as to be in contact with the outer peripheral surface of the outer ring, and the insulating portion of the insulating bush is fitted so as to be in contact with the inner peripheral surface of the housing. Even in this case, it is possible to prevent the insulating portion from being attached to the outer ring and falling off from the housing due to the shrinkage of the insulating portion.

Further, in the configurations of FIGS. 2 and 3, the insulating portion and the metal portion are separately formed, but the resin composition is insert-molded on the outer peripheral surface of the metal portion, the resin paint is applied by various coating methods, and the like. Then, the resin molded body or the resin coating film may be integrally formed with the metal portion. Also in this case, it is preferable to use a split bush for the metal portion. Further, another layer may be interposed between the insulating portion and the metal portion.

The insulated rolling bearing of the present invention is used, for example, in an electrolytic corrosion prevention bearing used in an electric motor of a refrigerant compressor and an electrolytic corrosion prevention bearing of an electric motor. Further, as shown in Examples described later, since it has a sufficient extraction force even in a thermal shock test of -30 ° C to 160 ° C, it can be used as an electrolytic corrosion prevention bearing used in a wide temperature range from low temperature conditions to high temperature conditions. Especially suitable. For example, it is applied to electrolytic corrosion prevention bearings used in both temperature ranges of 0 ° C. or lower and 100 ° C. or higher.

Example 1
PEEK resin was injection molded to obtain a cylindrical member. This cylindrical member is fitted to the inner peripheral surface of the inner ring made of SUJ2, and further, a split bush made of SUS304 is fitted to the inner peripheral surface of the cylindrical member to obtain a test member having the form shown in FIG. rice field.

Example 2
PEEK resin was injection molded to obtain a cylindrical member having a tapered outer peripheral surface. This cylindrical member was fitted to the inner peripheral surface of the inner ring made of SUJ2, and further, a split bush made of SUS304 was fitted to the inner peripheral surface of the cylindrical member to obtain a test member having the form shown in FIG.

Example 3
Atmospheric plasma spraying was performed on the outer peripheral surface of an austenitic stainless steel cylindrical member to obtain an insulating bush having a ceramic spray coating. Alumina was used as the thermal spray material.

Comparative Example 1
PEEK resin was injection molded to obtain an insulating bush made of a single insulating portion. This insulating bush was fitted to the inner peripheral surface of the inner ring made of SUJ2 to obtain a test member having the form shown in FIG. 5 (a).

Comparative Example 2
An amalfa treatment was applied to the inner peripheral surface of a cylindrical member made of SUS304 to form a fine uneven shape, and then a PPS resin was insert-molded on the inner peripheral surface to obtain an insulating bush having an injection-molded layer. This insulating bush was fitted to the inner peripheral surface of the inner ring made of SUJ2 to obtain a test member having the form shown in FIG. 5 (b).

Table 1 shows the linear expansion coefficients such as the materials of the parts used in Examples 1 to 3 and Comparative Examples 1 and 2.

<Extraction force test>
A shaft made of S45 was inserted into the shaft hole of each test member and placed in a constant temperature bath, and thermal shock was repeatedly applied. The thermal shock was carried out for 200 cycles with a set of high temperature conditions of 160 ° C. and 30 minutes and low temperature conditions of −30 ° C. and 30 minutes. After 200 cycles, the shaft was pulled out, and the test member was subjected to a pull-out force test under the following conditions.
Measuring instrument: Autograph Measurement speed: 5 mm / sec
Judgment criteria: 200N or more

Figure 6 shows the outline of the withdrawal force test. As shown in FIG. 6, the test member 17 after applying thermal shock is placed on the receiving jig 18, and is placed on the end surface of the insulating bush 17b fitted to the inner peripheral surface of the inner ring 17a of the test member 17. The push jig 19 was applied. A load was applied to the pushing jig 19 in the direction of the arrow, and the peak of the load until the insulating bush 17b was completely removed from the receiving jig 18 was measured. Table 1 shows the number of passes with respect to the number of tests, assuming that the load is 200 N or more.

<Energization test>
The outline of the energization test is shown in FIG. As shown in FIG. 7, an iron shaft S is inserted into the test member 17, and each terminal of the insulation resistance measuring instrument 20 is applied to the shaft S and the outer peripheral surface of the inner ring 17a of the test member 17 under the following conditions. The insulation resistance value was measured. In each test example, 3 samples were measured and the average value is shown in Table 1.
Applied voltage: DC500V
Temperature: 15-25 ° C (room temperature)
Humidity: 40-60%

As shown in Table 2, Examples 1 to 3 and Comparative Example 2 passed all the test numbers, showed a pull-out force of 1000 N or more, and had a sufficient pull-out force even after the thermal impact test. In addition, in Examples 1 to 3 and Comparative Example 2, no hugging to the shaft was observed. However, in the case of Comparative Example 2, it is conceivable that the inner diameter dimension may become smaller as a result of the volume expansion escaping to the inner diameter side due to the shape constraint of the metal portion on the outer diameter side at high temperature. On the other hand, in Examples 1 to 3, since the insulating portion is sandwiched between the inner ring and the metal portion and is urged in the direction of being pressed against the inner ring by the metal portion, the volume change of the insulating portion due to the temperature change. It is considered that the dimensional stability of the inner diameter can be further improved.

On the other hand, in Comparative Example 1, after the thermal shock test, the insulating bush was attached to the shaft in all the test numbers, so that the insulating bush and the shaft were pulled out together from the inner ring (see FIG. 8). Of the five tests, one passed, and three of the remaining four failed, the shrinkage of the insulating bush eliminated the tightening allowance between the inner ring and the insulating bush, and the insulating bush and shaft were self-weighted from the inner ring. The result was that it came out. Further, as shown in FIG. 8, cracks were also confirmed in the insulating bush.

In the energization test, in all cases, the shaft did not come into metal contact with the inner peripheral surface of the inner ring, showing insulation.

Subsequently, when the manufacturing cost of the insulating bush of Comparative Example 2 was set to 1, the manufacturing cost of other insulating bushes was quantified. The results are shown in FIG.

As shown in FIG. 9, the insulating bush of Comparative Example 2 requires a special surface treatment and is injection molded, so that the cost is increased as compared with the others. On the other hand, the insulating bushes of Examples 1 and 2 have a metal portion and an insulating portion composed of a split bush and a cylindrical member made of resin, and do not require special surface treatment or injection molding, so that the manufacturing cost is significantly increased. Can be reduced to. In particular, in the second embodiment, the outer peripheral surface of the resin cylindrical member has a tapered shape and can be fitted into the inner ring even if there is a mutual difference in dimensions, so that the manufacturing cost can be further reduced. Further, although the insulating bush of Example 3 requires thermal spraying of ceramics, it is sprayed on the outer peripheral surface, so that the manufacturing cost can be reduced as compared with the case of thermal spraying on the inner peripheral surface. For example, in ceramic spraying, if the manufacturing cost when sprayed on the inner peripheral surface is 1, the manufacturing cost when sprayed on the outer peripheral surface is about 0.4 (see FIG. 10).

As described above, the insulated rolling bearing of the present invention can prevent the bearing from sticking to the shaft and falling off from the inner ring even in a wide temperature range, and can maintain dimensional stability, so that the shaft can be stably supported. can. In addition, the cost of the insulated rolling bearing can be reduced.

The insulated rolling bearing of the present invention can prevent electrolytic corrosion, as well as hugging to a shaft or the like and preventing it from falling off from an inner ring or the like. Therefore, an electrolytic corrosion prevention bearing that supports the shaft of an electric motor or the shaft of a refrigerant compressor. Can be widely used as.

1 Insulated rolling bearing 2 Inner ring 3 Outer ring 4 Ball 5 Cage 6 Seal member 7 Grease 8 Insulation part 9 Metal part 10 Insulation bush 11 Insulation part 12 Metal part 13 Insulation bush 14 Insulation part 15 Metal part 16 Insulation bush 17 Test member 18 Jig 19 Pushing jig 20 Insulation resistance measuring instrument S shaft

Claims

Insulation with inner and outer rings made of steel, a plurality of rolling elements interposed between the inner and outer rings, and a substantially cylindrical insulating bush fitted to the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring. It ’s a rolling bearing,
The insulating bush is an insulating rolling bearing characterized by having an insulating portion made of a resin composition on the outer diameter side and a metal portion on the inner diameter side.
The insulating rolling bearing according to claim 1, wherein the insulating portion and the metal portion are formed separately.
The metal portion is a split bush in which a mating opening is formed in a part in the circumferential direction, and the insulating portion is a cylindrical member that covers the mating opening of the split bush from the outer diameter side. 2. The insulated rolling bearing according to 2.
The insulating rolling bearing according to claim 3, wherein the outer peripheral surface of the insulating portion has a tapered shape whose diameter increases from one side in the axial direction toward the other side.
The base resin of the resin composition of the insulating portion is a polyphenylene sulfide resin, a polyether ketone resin, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, a tetrafluoroethylene-hexafluoropropylene copolymer resin, or a tetra. The insulated rolling bearing according to claim 1, wherein the fluoroethylene-ethylene copolymer resin is used.
The insulated rolling bearing according to claim 1, wherein the metal portion is carbon steel for machine structure or stainless steel.