Insulating rolling bearing

Abstract

The insulating rolling bearing (21) has a bearing body section (Bh) and an insulating bush (28). An insulating bush (28) is press-fitted to an inner ring inner peripheral portion (22a) of the bearing body portion (Bh). The insulating bush (28) has a metal circular ring (28a) and an insulating resin (28b) provided on the inner peripheral surface of the metal circular ring (28a). The metal circular ring (28a) and the insulating resin (28b) have prescribed linear expansion coefficients similar to each other, and are integrally provided. The insulating resin (28b) penetrates into a plurality of holes formed in the inner peripheral surface of the metal circular ring (28a) and is closely attached to the metal circular ring (28a). The holes in the metal circular ring (28a) are micropores of several nm to tens of nm. The ratio of the linear expansion coefficient of the metal circular ring (28a) to the linear expansion coefficient of the insulating resin (28b) is 0.87-2.25 when the metal circular ring (28a) is 1.

Description

Technical Field

[0001] The present invention relates to an insulating rolling bearing, and for example, to an insulating rolling bearing used for a rotating part of various electric motors used in general industrial machinery and the like. Background Art

[0002] In rolling bearings, corrosion called electrolytic corrosion occurs on the raceway surfaces of the inner and outer rings and the rolling surfaces of the rolling elements, reducing durability. This phenomenon can be addressed by making the rolling bearings insulating. Generally, in order to make the rolling bearings insulating, it is effective to spray ceramics on the rolling bearings or use ceramic balls for the rolling elements. However, in this case, the manufacturing cost of silicon nitride as a ceramic raw material and the material cost affect the cost.

[0003] In order to provide a rolling bearing with insulation performance at a low cost and in a simple manner, the rolling bearing can be provided with insulation performance by press-fitting an insulating bushing into the inner diameter of the inner ring or the outer diameter of the outer ring.

[0004] In the refrigerant compressor described in Patent Document 1, a resin sleeve is embedded in the inner circumferential surface of the inner ring by means of press fitting or the like. However, under actual operating conditions of repeated heating and cooling, there is a concern that the resin sleeve may hug the crankshaft and may be detached from the inner ring. In addition, it is considered to embed the same resin sleeve in the outer circumferential surface of the outer ring to achieve insulation, but there is a concern that the resin sleeve may hug the outer ring and may be detached from the housing.

[0005] Therefore, in order to solve the above problem, the insulating rolling bearings of Patent Documents 2 to 4 are formed by embedding an insulating resin in a metal ring as an insulating bushing. The insulating bushing suppresses the expansion of the resin relative to the metal ring even under the conditions where the metal and the resin are strongly in close contact and are repeatedly heated and cooled. Therefore, the resin does not hug the crankshaft, or the insulating bushing does not fall off the inner ring.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-40261

[0009] Patent Document 2: Japanese Patent Application Publication No. 2021-55748

[0010] Patent Document 3: Japanese Patent Application Publication No. 2021-143713

[0011] Patent Document 4: Japanese Patent Application Publication No. 2022-38349 Summary of the invention

[0012] Problems to be solved by the invention

[0013] However, although the rolling bearings in Patent Documents 2 to 4 have an insulating bushing in the inner ring, when the insulating bushing is pressed into the inner ring and embedded in the shaft, there is a problem that the bushing cannot be tightly fitted. The tight fitting of the resin of the insulating bushing pressed into the inner diameter of the inner ring and the shaft may cause abnormality or creep of the resin.

[0014] <About the classification of insulation parts according to load classification>

[0015] [Table 1]

[0016] Feasibility of bonding and coating of load-classified insulating parts

[0017]

[0018] Under the load conditions of inner ring rotation and outer ring rotation, the outer diameter of the outer ring fits tightly. Therefore, when the outer ring is installed on the housing, there is a possibility of abnormalities such as peeling of the insulation coating, so it is avoided to apply insulation coating to the outer diameter of the outer ring.

[0019] Therefore, even if the inner diameter of the inner ring is provided with an insulating coating, there is little possibility that the insulating coating will peel off when the inner ring is mounted on the shaft.

[0020] The refrigerant compressor described in Patent Document 1 is used under the conditions where the inner ring rotates and the outer ring rotates under load, and therefore the insulating bushing described in Patent Document 2 can be applied to the inner diameter of the inner ring.

[0021] Under the conditions of inner ring rotation and inner ring rotation load, the outer diameter of the outer ring fits loosely. Therefore, even if the outer diameter of the outer ring is coated with insulation, the possibility of abnormalities such as peeling of the insulation coating when the outer ring is installed on the housing is still small.

[0022] Therefore, when the inner ring is provided with an insulating coating, when the inner ring is mounted on the shaft, there is a possibility that the insulating coating may peel off or cause abnormalities such as creep.

[0023] For the reasons described above, ceramic spraying or resin injection molding is applied to the outer diameter of the outer ring in order to make the bearing insulating under the conditions of inner ring rotation and inner ring rotation load.

[0024] For these reasons, it is possible to avoid insulating coating on the inner diameter of the inner ring under the conditions of inner ring rotation and inner ring rotation load.

[0025] Insulating bushings are integrated products of metal and resin, but if the adhesion is insufficient, the resin will leave the metal ring when it cools after thermal expansion, so there is a possibility that the resin will cling to the shaft and cause abnormalities.

[0026] Furthermore, in the outer ring insulation coating, it is unavoidable that electric current, which is one of the main causes of electric corrosion, flows to the bearing.

[0027] If the inner diameter of the inner ring is insulated, the current from the shaft can be avoided, so a further anti-corrosion effect can be expected.

[0028] An object of the present invention is to provide an insulating rolling bearing that can cope with tight fitting under predetermined conditions.

[0029] Technical solutions to solve problems

[0030] (Technical Solution 1)

[0031] The insulating rolling bearing of the present invention relates to an insulating rolling bearing in which an insulating bushing is pressed into the inner circumference of the inner ring;

[0032] The insulating bushing includes a metal ring and an insulating resin provided on an inner peripheral surface of the metal ring. The metal ring and the insulating resin have predetermined linear expansion coefficients that are similar to each other and are provided integrally.

[0033] The above-mentioned “predetermined linear expansion coefficients that are similar to each other” are linear expansion coefficients arbitrarily determined by design or the like, and are determined by, for example, obtaining an appropriate linear expansion coefficient through either or both of tests and simulations under conditions of repeated cooling and heating.

[0034] The above-mentioned “integrally provided” means that the metal ring and the insulating resin have a close contact force that does not separate from each other due to insert molding or the like.

[0035] According to this structure, by pressing the insulating bushing into the inner circumference of the inner ring, it is possible to have insulation. In this case, compared with the existing technology of spraying ceramics on the bearing, the insulating rolling bearing can be assembled easily and at low cost, and the bearing can be easily assembled. Since the metal ring and the insulating resin have predetermined linear expansion coefficients that are similar to each other and are provided integrally, the insulating rolling bearing can be fastened and embedded relative to the shaft. Therefore, the insulating rolling bearing can also be pressed into the shaft and used under the predetermined conditions of inner ring rotation and inner ring rotation load. Since the insulating bushing is pressed in with a sufficient tightening margin so that it does not fall off from the inner circumference of the inner ring, it has a high pull-out force and the insulating bushing will not fall off from the inner ring during operation. The insulating bushing in use will maintain a sufficient tightening margin even in normal temperature and high temperature environments, so there is no need to worry about falling off, and the insulating bushing and the inner ring will not have abnormalities such as creep.

[0036] (Technical Solution 2)

[0037] The insulating resin may also penetrate into a plurality of holes formed on the inner circumferential surface of the metal ring to achieve close contact. In this case, the insulating resin penetrates into the plurality of holes of the metal ring without gaps, and a high close contact force can be maintained by an anchoring effect.

[0038] (Technical Solution 3)

[0039] The holes of the metal ring may also be micropores of several nm to several tens of nm. In this case, the insulating resin can reliably maintain a higher adhesion force relative to the metal ring. If the holes are smaller than the several nm, the insulating resin may not be able to fully penetrate into the plurality of holes. If the holes exceed the several tens of nm, the anchoring effect may not be exerted.

[0040] (Technical Solution 4)

[0041] The ratio of the linear expansion coefficients of the metal ring and the insulating resin can be 0.87 to 2.25, with the metal ring being 1. In this way, the metal ring and the insulating resin are integrally provided on the basis of defining the linear expansion coefficient ratio of the metal ring and the insulating resin, so that the insulating rolling bearing can be securely fastened and embedded with respect to the shaft.

[0042] (Technical Solution 5)

[0043] The metal ring can be carbon steel, copper or austenitic stainless steel for mechanical structure. These carbon steel, copper or austenitic stainless steel for mechanical structure expand to the same extent as the inner and outer rings, such as bearing steel, so that sufficient tightening margin between the inner ring of the bearing can be ensured, and the reduction of the tightening margin between the inner ring of the bearing and the metal ring can be prevented.

[0044] (Technical Solution 6)

[0045] The insulating resin may also be made of PPS or PEEK. In this case, the linear expansion coefficient of the insulating resin can be made close to that of the metal ring and smaller. Therefore, it is possible to prevent the reduction of the tightening margin due to the fitting with the shaft of the insulating bushing. Since the insulating resin made of PPS or PEEK has a relatively high hardness, when the insulating rolling bearing is fastened and embedded relative to the shaft, it is possible to prevent the insulating resin from creeping in the future.

[0046] (Technical Solution 7)

[0047] It can also be used under the conditions of inner ring rotation and inner ring rotation load. It is possible to realize an insulating rolling bearing that can cope with tight fitting even under the above conditions.

[0048] Any combination of at least two structures disclosed in the claims and / or the specification and / or the drawings is also included in the present invention. In particular, any combination of more than two of the claims in the claims is also included in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and the accompanying drawings are for illustration and description only and should not be used to limit the scope of the present invention. The scope of the present invention is determined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings represent the same or equivalent parts.

[0050] Figure 1 It is a longitudinal sectional view of the insulating rolling bearing according to the first embodiment of the present invention.

[0051] Figure 2 A three-dimensional diagram of an insulating bushing of the insulating rolling bearing;

[0052] Figure 3 for Figure 1 A partial enlarged view of Part III;

[0053] Figure 4 is an exploded perspective view of the insulating rolling bearing;

[0054] Figure 5 A diagram showing the general situation of the pull-out force test;

[0055] Figure 6 A diagram showing the appearance of a comparative example after a pull-out force test;

[0056] Figure 7 A diagram showing the measurement position of the inner diameter of the resin before and after the heat shock test;

[0057] Figure 8 is a diagram showing an operating cycle of a thermal shock test;

[0058] Fig.9A A diagram showing an overview of a test of the tightness of a metal ring and an insulating resin;

[0059] Fig. 9B for Fig.9A A partial enlarged view of section IXB in FIG.

[0060] Fig.10 It is a graph showing the adhesion of the insulating bushings of the embodiment and the comparative example;

[0061] Fig.11 It is a cross-sectional view of a refrigerant compressor using the insulating rolling bearing. DETAILED DESCRIPTION

[0062] [First embodiment]

[0063] and Figures 1 to 4 The insulating rolling bearing according to the embodiment of the present invention will be described together. The insulating rolling bearing is used as a rotating part in various motors used in general industrial machinery, etc. However, the insulating rolling bearing is not limited to the above-mentioned use.

[0064] <General structure of insulating rolling bearing>

[0065] like Figure 1 As shown, the insulating rolling bearing 21 has a bearing body Bh and an insulating bushing 28 pressed into the inner circumference 22a of the inner ring of the bearing body Bh. The bearing body Bh is a deep groove ball bearing, and has inner and outer rings 22, 23, a plurality of rolling elements 24 between the inner and outer rings 22, 23, a retainer 25 that holds the plurality of rolling elements 24 at regular intervals in the circumferential direction, and sealing members 26, 26 arranged at both ends in the axial direction. The rolling element 24 is a ball, and the inner and outer rings 22, 23 and the ball 24 are formed of bearing steel such as SUJ2, martensitic stainless steel, etc. The bearing space between the inner and outer rings 22, 23 is filled with grease 27, and the bearing space is sealed by the above-mentioned sealing members 26, 26.

[0066] <About Insulating Bushings>

[0067] like Figure 2 As shown in FIG. 1 , the insulating bushing 28 includes a metal ring 28a on the outer diameter side and an insulating resin 28b provided on the inner circumference of the metal ring 28a. The metal ring 28a and the insulating resin 28b have predetermined linear expansion coefficients similar to each other and are provided integrally. Figure 3 As shown, the insulating resin 28b penetrates into the plurality of holes h formed on the inner peripheral surface of the metal ring 28a and adheres to the metal ring 28a. The holes h of the metal ring 28a are micropores with a size of several nanometers or more and several tens of nanometers or less.

[0068] like Figure 4 As shown in the figure, the insulating bushing 28 is pressed and fitted on the inner peripheral portion 22a of the inner ring, and then Figure 1 As shown in the figure, by inserting the shaft 5 into the shaft hole of the insulating bushing 28, the shaft 5, the insulating bushing 28 and the inner ring 22 can rotate integrally. When the shaft 5 rotates, the insulating resin 28b contacts the outer peripheral surface of the shaft 5 without sliding. The insulating resin 28b is interposed between the inner ring 22 and the metal ring 28a and the shaft 5, thereby cutting off the shaft current from flowing to the bearing body Bh via the shaft 5.

[0069] <Metal ring>

[0070] like Figure 2As shown, the metal ring 28a is a roughly cylindrical metal ring that can be embedded in the inner diameter through a special surface treatment described later. The metal ring 28a is a metal having a linear expansion coefficient equivalent to that of bearing steel, for example, carbon steel for mechanical structures such as S45C, copper, or austenitic stainless steel such as SUS304. Since these metals expand to the same extent as bearing steel, sufficient tightening margin relative to the shaft is ensured to prevent the reduction of the tightening margin of the bearing inner ring and the metal ring 28a. The above metals can also be plated with zinc, nickel, copper, etc. The thickness of the metal ring 28a is not particularly limited, and it is preferred that the thickness of the metal ring 28a is greater than the thickness of the insulating resin 28b. The thickness of the metal ring 28a is preferably 0.5mm to 5mm, and more preferably 1mm to 3mm.

[0071] <Insulating resin>

[0072] In order to prevent the reduction of the tightening margin due to the fitting with the shaft, the insulating resin 28b of the insulating bushing 28 pressed into the inner ring preferably has a linear expansion coefficient close to that of the metal ring 28a, and preferably a smaller value. The ratio of the linear expansion coefficients of the metal ring 28a and the insulating resin 28b is 0.87 to 2.25 when the metal ring 28a is 1. The insulating resin 28b has a high hardness in a manner that does not creep due to the tight fitting, and preferably has creep resistance. From the viewpoint of preventing abnormalities of the insulating resin itself, the insulating resin 28b is preferably a resin with heat shock resistance.

[0073] As a resin that satisfies all of the above, for example, there is polyphenylene sulfide (PPS) or polyetheretherketone (PEEK). An additive may be appropriately added to the insulating resin 28b. As an additive, a non-conductive reinforcing material such as glass fiber, aramid fiber, potassium titanate whisker, titanium oxide whisker, etc. is preferably added because it can improve creep resistance.

[0074] As a specific form of the insulating resin 28b, for example, it is preferred to use PPS resin as the base resin and glass fiber as the additive. The glass fiber more preferably contains 10 wt% to 30 wt% of the total insulating resin. The thickness of the insulating resin 28b is preferably 0.1 mm to 2 mm, more preferably 0.1 mm to 1 mm, and further preferably 0.1 mm to 0.5 mm, because the deformation caused by the load during use can be reduced by thinning.

[0075] <Surface treatment, etc.>

[0076] The bonding surface of the metal ring 28a with the insulating resin 28b is preferably roughened into a concavoconvex shape by shot blasting, tumbling, machining, etc., in order to improve the adhesion strength between the metal ring 28a and the insulating resin 28b. In this case, the surface roughness Ra is preferably 4 μm or more.

[0077] In particular, in order to improve the adhesion between the metal ring 28a and the insulating resin 28b, it is preferred to perform a chemical surface treatment on the bonding surface of the metal ring 28a and the insulating resin 28b. As the chemical surface treatment, it is preferred to perform (1) a treatment for forming a fine concavo-convex shape on the bonding surface, or (2) a treatment for forming a bonding film that chemically reacts with the insulating resin 28b on the bonding surface.

[0078] By making the bonding surface into a fine concavoconvex shape, the actual bonding area is increased, and the adhesion strength between the insulating resin 28b and the metal ring 28a is further improved. In addition, by sandwiching a bonding film that chemically reacts with the insulating resin 28b on the bonding surface, the adhesion strength between the insulating resin 28b and the metal ring 28a is further improved.

[0079] As a surface roughening treatment to form a fine concavoconvex shape, a method of dissolving the inner circumference of the metal ring 28a by acid solution treatment (sulfuric acid, nitric acid, hydrochloric acid, etc. or mixed with other solutions) or alkaline solution treatment (sodium hydroxide, potassium hydroxide, etc. or mixed with other solutions) can be cited. The fine concavoconvex shape varies according to the concentration, treatment time, post-treatment, etc., but in order to improve the adhesion of the anchoring effect, fine concavoconvex with a concave spacing of several nm to tens of μm is preferred. In addition, in addition to the general acid solution treatment and alkaline solution treatment, special AMALPHA treatment of MEC Co., Ltd. and NMT treatment of Dachengjia Co., Ltd. can also be cited.

[0080] When the insulating resin 28b is formed by injection molding, the resin material flows in at a high speed, so the resin material can also penetrate into the fine concave-convex shape with a concave pitch of several nm to several tens of μm by shear force. Thus, the adhesion strength between the metal ring 28a and the insulating resin 28b can be ensured. In addition, since the fine concave-convex shape formed by chemical surface treatment is different from a simple rough shape mechanically, it is a complex three-dimensional structure such as a porous material, so it is easy to exert an anchoring effect and can be firmly adhered.

[0081] As a surface treatment for forming a bonding film that chemically reacts with the insulating resin 28b, an immersion treatment in a solution of a triazine dithiol derivative, an s-triazine compound, etc. can be cited. When the treated metal ring 28a is placed in a mold for injection molding, these surface treatments react with the resin material through heat and pressure, thereby improving the adhesion between the insulating resin 28b and the metal ring 28a. As such a surface treatment, for example, TRI treatment of Toa Denka Co., Ltd. (Toa Denka Co., Ltd.) can be cited.

[0082] Among chemical surface treatments, special surface treatments such as AMALPHA treatment of MEC Co., Ltd., NMT treatment of Dacheng Plas Co., Ltd., and TRI treatment of Toa Denka Co., Ltd. are suitable for aluminum and copper. In addition, as described above, the metal ring 28a preferably has the same linear expansion coefficient as that of bearing steel. Therefore, when implementing these treatments, it is preferred that at least the inner peripheral surface of the metal ring 28a is copper.

[0083] <Structure and tightness of insulating bushing>

[0084] like Figure 3 As shown in FIG. 1 , by subjecting the metal ring 28a to the above-mentioned special surface treatment, micropores h of a size of several nm to several tens of nm are formed on the metal surface. The metal ring 28a is set in a mold and integrated with the insulating resin 28b by insert molding. The insulating resin 28b is bonded to the metal ring 28a mainly by the anchoring effect, and the insulating resin 28b penetrates into the above-mentioned micropores h without gaps. By the above-mentioned surface treatment, the metal ring 28a and the insulating resin 28b are strongly adhered, and the insulating resin 28b will not peel off from the metal ring 28a even under the harsh conditions of repeated cooling and heating.

[0085] <Structure and fastening of insulating bushing and inner ring>

[0086] like Figure 4 As shown in FIG. 1 , by heating the inner ring 22 of the bearing body Bh, the inner ring inner diameter expands and is tightly fitted with the insulating bushing 28. Since the insulating resin 28b has a linear expansion coefficient close to that of metal, Figure 1 As shown, the shaft 5 can be fastened and embedded in the inner diameter of the inner ring. In this case, the insulating bushing 28 can be pressed into the inner circumference 22a of the inner ring without insulating coating on the inner diameter of the inner ring, and there is no abnormality such as peeling off when the shaft is installed like the insulating coating.

[0087] The insulating bushing 28 pressed into the inner ring 22 can be tightly fitted, and the inner diameter dimensional accuracy can be suppressed to a maximum of about 5 μm or less. Therefore, the insulating bushing 28 can achieve the same dimensional accuracy as the bearing body Bh. In addition, since the thermal expansion of the insulating resin 28b is dominated by the metal, the insulating rolling bearing 21 can operate while maintaining a tightly fitted state during operation.

[0088] <Insulating bushing and inner ring structure and pull-out force>

[0089] In the case of the insulating bush made of resin as in Patent Document 1, the insulating bush shrinks under the condition of repeated heating and cooling. Therefore, there is a concern that the insulating bush may be caught by the shaft during operation and fall off the inner ring.

[0090] On the other hand, the metal ring 28a of the insulating bushing 28 of the present embodiment has a large tightening margin that does not fall off from the inner diameter of the inner ring, and has a strong pull-out force. Therefore, it is possible to prevent the insulating bushing 28 from falling off during operation.

[0091] <Structure and assembly properties of insulating bushings>

[0092] In Patent Document 1, an insulating bushing is embedded in the inner diameter of the inner ring, but the flange of the flange portion of the insulating bushing is a shape that protrudes from the bearing end face in the axial direction. Therefore, when assembling the bearing, it is necessary to consider the protruding flange and reconsider the design of the housing. This type will change the width dimension of the bearing. Therefore, when assembling the bearing, it is necessary to consider the change in the width dimension and reconsider the assembly process.

[0093] In contrast, the insulating bushing 28 in the insulating rolling bearing 21 of this embodiment does not protrude axially from the end surface of the bearing body Bh. Therefore, there is no need to reconsider the design of the housing, and the width dimension of the insulating rolling bearing 21 does not change, which is also convenient for bearing assembly.

[0094] Example

[0095] Comparative Example 1

[0096] The PEEK resin was injection molded to obtain an insulating bushing composed only of insulating resin. The insulating bushing was fitted into the inner circumference of an inner ring made of SUJ2 to obtain a test component of Comparative Example 1.

[0097] Example 1

[0098] The above-mentioned surface treatment was applied to the inner circumference of a metal ring made of austenitic stainless steel. The metal ring was placed in a mold, and an insulating resin made of PPS was formed on the inner circumference of the metal ring by injection molding, thereby obtaining an insulating bushing. The insulating bushing was fitted into the inner circumference of an inner ring made of SUJ2 to obtain a test component of Example 1.

[0099] Example 2

[0100] The above-mentioned surface treatment was applied to the inner circumference of a metal ring as a carbon steel pipe (STKM) for machine structure. The metal ring was placed in a mold, and an insulating resin composed of PPS was formed on the inner circumference of the metal ring by injection molding, thereby obtaining an insulating bushing. The insulating bushing was fitted into the inner circumference of an inner ring made of SUJ2 to obtain a test component of Example 2.

[0101] <Pull-out force test>

[0102] In order to consider the possibility of the insulating bushing falling off, the pull-out force test described below was performed on each test component to measure the pull-out force of the insulating bushing. The pass standard was set to 1000N or more, and the force required to pull out the insulating bushing from the inner diameter of the inner ring at room temperature and at a high temperature of 160°C was measured. In addition, the pull-out force after the thermal shock test was also measured. Thermal shock is Figure 8 As shown in Table 2, 200 cycles were performed using a set of high temperature conditions of 160° C. for 30 minutes and a set of low temperature conditions of −30° C. for 30 minutes.

[0103] [Table 2]

[0104] Thermal shock test conditions

[0105]

[0106] The conditions of the pull-out force test are as follows.

[0107] Measuring instrument: Precision universal testing machine (trade name: Autograph)

[0108] Measuring speed: 5mm / sec

[0109] Judgment standard: Pass when the load is above 1000N

[0110] The pull-out force test is as follows Figure 5 As shown. Figure 5As shown, the test component 17 is supported on the receiving fixture 18, and the pressing fixture 19 is brought into contact with the end surface of the insulating bushing 17b fitted to the inner circumference of the inner ring 17a of the test component 17. A load is applied to the pressing fixture 19 in the direction of arrow A1, and the peak value of the load until the insulating bushing 17b falls off the receiving fixture 18 is measured.

[0111] <Pull-out force measurement results>

[0112] [Table 3]

[0113] Pull-out force test results

[0114]

[0115] Examples 1 and 2 had sufficient pull-out force of 1000 N or more in all test numbers at room temperature and high temperature. No tight grip of the insulating bushing on the shaft was observed in Examples 1 and 2. Even when Examples 1 and 2 were used under repeated conditions of heating and cooling, sufficient pull-out force was observed after the thermal shock test, and no tight grip of the insulating bushing on the shaft was observed.

[0116] On the other hand, in Comparative Example 1, in which the insulating bushing is composed only of PEEK resin, 3 out of 10 tests were passed at room temperature, and 0 was passed after the thermal shock test. In addition, in Comparative Example 1, after the pull-out force test after the thermal shock test, the PEEK resin was tightly held on the shaft from the inner ring of the bearing, as shown in FIG. Figure 6 As shown in the figure, the insulating bushing and the shaft fell off the inner ring due to their own weight. As a result, for three of the unqualified ones, the insulating bushing shrank, the tightening margin between the inner ring and the insulating bushing disappeared, and the insulating bushing and the shaft fell off the inner ring due to their own weight. Figure 6 As shown in the enlarged view on the right, abnormality of the insulating bushing was also confirmed.

[0117] <Dielectric Breakdown Voltage>

[0118] As shown in Table 4, the insulating bushing has a dielectric breakdown voltage of 1500 V when the insulating resin has a thickness of 0.1 mm, and has a dielectric breakdown voltage of 15 MV when the insulating resin has a thickness of 2.0 mm.

[0119] [Table 4]

[0120] Dielectric breakdown voltage

[0121] thickness Withstand voltage 2.0(mm) 15.0(MV) 0.1(mm) 1500(V)

[0122] <Chimera>

[0123] The linear expansion coefficients of the metal ring and the insulating resin are shown in Tables 5 and 6 below.

[0124] [Table 5]

[0125] Linear expansion coefficient of metal ring

[0126] Linear expansion coefficient ( / ℃) Bearing Steel 1.25E-05 Carbon Steel 1.02E-05 copper 1.65E-05 SU304 1.73E-05

[0127] [Table 6]

[0128] Linear expansion coefficient of insulating resin

[0129] Linear expansion coefficient ( / ℃) PPS 2.30E-05 PEEK 1.50E-05

[0130] Table 7 shows the change rates of the inner diameter dimensions of the insulating resin before and after the heat shock test. Figure 7 It is a figure which shows the measurement position of the resin inner diameter before and after the heat shock test.

[0131] [Table 7]

[0132] Changes in the inner diameter of the resin before and after the thermal shock test

[0133]

[0134] As shown in Table 7, after the thermal shock test, the inner diameter of the insulating resin changes slightly, so the shaft and the insulating bushing can be tightly fitted even under repeated cooling and heating conditions. In addition, according to the pull-out force measurement results in Table 3, the insulating bushing does not tightly hug the shaft and fall off by its own weight, and the inner ring and the insulating bushing can be tightly fitted.

[0135] <Adhesion between metal ring and insulating resin>

[0136] The outline of the tightness test is as follows: Fig.9A As shown. Fig.9A and Fig. 9B As shown in FIG. 1 , a test component 31 of an insulating bushing is pressed into a hollow cylindrical retainer 30, and a pressing fixture 32 is supported on the resin portion 31b of the test component 31. Thus, only the resin portion 31b is pressed. A load is applied to the pressing fixture 32 in the direction of arrow A2 by a pressing fixture 33, and the sealing force is measured. The sealing force test results of the metal ring 31a and the insulating resin as the resin portion 31b are shown in Table 8. In addition, the sealing force curve after the heat shock test is as shown in FIG. Fig.10 shown.

[0137] [Table 8]

[0138] Results of the tightness test

[0139]

[0140] If the metal ring and the insulating resin are not in close contact, Fig.10 As in the comparative example, when the maximum adhesion force (about 20% of the acceptable standard) was applied to the bonding surface between the annular portion and the resin portion, only the insulating resin peeled off.

[0141] In contrast, in Fig.10 In the embodiment of the invention, the resin is bonded to the metal mainly by the anchoring effect on the metal ring with micropores of tens of nanometers or less formed by the special surface treatment. The resin penetrates into the micropores of tens of nanometers or less without gaps, and the adhesion is improved, and a maximum adhesion of about 10 times can be obtained compared with the comparative example.

[0142] In the example, the close fit test performed at room temperature and after the thermal shock test showed that the close fit was above the qualified standard, so it was sufficient close fit. Therefore, even under the conditions of thermal expansion and cooling, the resin will not leave the metal, and the metal will expand together with the resin, so it can also cope with the tight fitting, and the resin will not produce abnormalities.

[0143] <Effects>

[0144] According to the above description Figure 1 The insulating rolling bearing 21 can be made insulating by pressing the insulating bushing 28 into the inner circumference 22a of the inner ring. In this case, the insulating rolling bearing 21 can be assembled easily and at low cost compared with the prior art of spraying ceramics on the bearing, and the bearing 21 can be assembled easily. Since the metal ring 28a and the insulating resin 28b have predetermined linear expansion coefficients similar to each other and are integrally provided, the insulating rolling bearing 21 can be fastened and embedded relative to the shaft 5.

[0145] Therefore, the insulating rolling bearing 21 can be used even when the inner ring is rotated by press-fitting the shaft 5 and the inner ring is rotated under the specified conditions of the inner ring rotation load. The insulating bushing 28 is pressed in with a sufficient tightening margin so as not to fall off from the inner ring inner circumference 22a, so it has a high pull-out force and the insulating bushing 28 will not fall off from the inner ring 22 during operation. The insulating bushing 28 in use does not have a sufficient tightening margin even at normal temperature or high temperature environment, so there is no worry of falling off, and the insulating bushing 28 and the inner ring 22 will not have abnormalities such as creep.

[0146] The insulating resin 28a penetrates into the multiple holes formed on the inner peripheral surface of the metal ring 28a to be closely attached. In this case, the insulating resin 28b penetrates into the multiple holes of the metal ring 28a without gaps, and a high close contact force can be maintained by the anchor effect.

[0147] The ratio of the linear expansion coefficients of the metal ring 28a and the insulating resin 28b is 0.87 to 2.25 when the metal ring 28a is 1. In this way, when the metal ring 28a and the insulating resin 28b are integrally provided on the basis of specifying the ratio of the linear expansion coefficients of the metal ring 28a and the insulating resin 28b, the insulating rolling bearing 21 can be securely fastened and embedded with respect to the shaft 5.

[0148] <Other Implementation Methods>

[0149] The bearing body Bh may be a so-called open type deep groove ball bearing with one side sealed or without a seal.

[0150] The bearing body portion Bh may be, for example, an angular contact ball bearing, various roller bearings, or the like.

[0151] <Application examples of insulating rolling bearings>

[0152] like Fig.11 As shown in the figure, the insulating rolling bearing 21 of the embodiment can be applied to a refrigerant compressor. As the refrigerant compressor, a positive displacement scroll compressor is shown, but the insulating rolling bearing 21 of the embodiment can also be applied to positive displacement compressors of other compression methods such as a rotary type, a reciprocating type, a spiral type, etc. not shown in the figure. Fig.11 In the refrigerant compressor of the present invention, the rotating shaft 5 is rotatably supported on the center housing 3 and the motor housing 4 via the main bearing Mb and the auxiliary bearing Sb. The auxiliary bearing Sb is provided with an insulating rolling bearing 21. The insulating rolling bearing 21 as the auxiliary bearing is arranged on the anti-compression mechanism side of the motor M.

[0153] As described above, the preferred embodiments have been described with reference to the drawings, but various additions, changes, and deletions may be made without departing from the gist of the present invention. Therefore, such cases are also included in the scope of the present invention.

[0154] Description of the label:

[0155] Reference numeral 21 denotes an insulating rolling bearing;

[0156] Reference numeral 22a denotes the inner circumference of the inner ring;

[0157] Reference numeral 28 denotes an insulating bushing;

[0158] Reference numeral 28a denotes a metal ring;

[0159] Reference numeral 28b denotes an insulating resin;

[0160] The symbol h represents a hole.

Claims

1. An insulating rolling bearing, wherein: An insulating bushing is pressed into the inner circumference of the inner ring; The insulating bushing includes a metal ring and an insulating resin provided on an inner peripheral surface of the metal ring. The metal ring and the insulating resin have predetermined linear expansion coefficients that are similar to each other and are provided integrally.

2. The insulating rolling bearing according to claim 1, wherein: The insulating resin is infiltrated into a plurality of holes formed on the inner peripheral surface of the metal ring to be closely attached.

3. The insulating rolling bearing according to claim 2, wherein: The holes of the metal ring are micropores with a size of several nanometers to several tens of nanometers.

4. The insulating rolling bearing according to claim 1 or 2, wherein: The ratio of the linear expansion coefficients of the metal ring and the insulating resin is 0.87 to 2.25 when the metal ring is 1.

5. The insulating rolling bearing according to claim 1 or 2, wherein: The metal ring is carbon steel, copper or austenitic stainless steel for mechanical structure.

6. The insulating rolling bearing according to claim 1 or 2, wherein: The insulating resin is made of PPS or PEEK.

7. The insulating rolling bearing according to claim 1 or 2, wherein: It is used under inner ring rotation and inner ring rotation load conditions.

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