JP2019215017A - Rolling bearing - Google Patents

Abstract

To provide a rolling bearing to be used for auxiliary electric equipment or a continuously variable transmission, for which procurement of a steel product is facilitated, which is low in an environmental load, and which can suppress deterioration in service life due to early peeling resulting from hydrogen brittleness without depending on a lubricant.SOLUTION: A rolling bearing 1 to be used for auxiliary electric equipment or a continuously variable transmission includes an outer ring 11, an inner ring 12, and a plurality of rolling elements 13. The outer ring 11 has an outer ring raceway surface 11A on an inner peripheral face. The inner ring 12 has an inner ring raceway surface 12A on an outer peripheral face. Each of the plurality of rolling elements 13 has a rolling surface 13A in contact with the outer ring raceway surface 11A and the inner ring raceway surface 12A and rolls between the outer ring raceway surface 11A and the inner ring raceway surface 12A. On at least one of the outer ring raceway surface 11A, the inner ring raceway surface 12A and the rolling surface 13A, composite coating films 11B, 12B mainly composed of molybdenum oxide and molybdate are formed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rolling bearing, and more particularly, to a rolling bearing used for an electric accessory or a continuously variable transmission.

  In a bearing used for an electric auxiliary machine or a continuously variable transmission (CVT), early peeling occurs due to internal structure peeling due to normal rolling fatigue and white structure change different from surface starting peeling of an indentation starting point due to normal rolling fatigue. Sometimes. The paper "Brittle peeling and long life of electrical and auxiliary bearings" (Non-Patent Document 1) states that this early peeling is due to hydrogen embrittlement. Further, the mechanism of occurrence of early peeling is described as follows. When a rolling bearing is used under severe operating conditions such as rapid acceleration / deceleration, the sliding between the rolling surface and the rolling element increases, and an active new surface is generated on the rolling surface. By the catalytic action of the new surface, hydrogen is generated by decomposition of water mixed in the lubricant or the lubricant itself. When this hydrogen penetrates into the rolling surface, early peeling due to hydrogen embrittlement occurs. Therefore, it is effective to suppress the formation of a new surface as a measure against the early peeling due to the hydrogen embrittlement.

  For example, in Japanese Patent Application Laid-Open No. 2000-282178 (Patent Document 1), a large amount of chromium (Cr) is added to a steel material to form a passivation film on the steel surface, thereby suppressing the intrusion of hydrogen into the steel. A method is described.

  In Japanese Patent Publication No. 6-89783 (Patent Document 2), the surface of the rolling surface is inactivated by covering it with an oxide film, thereby eliminating the catalytic action of the metal and thereby reducing the hydrogen generated by the decomposition of the lubricant. A method for suppressing the occurrence is described.

  Further, in Japanese Patent Application Laid-Open No. 2005-112901 (Patent Document 3), by adding an additive containing molybdate as a main component to a lubricant of a rolling bearing, the additive of molybdate is added to a newly-formed surface during operation. A method has been proposed in which the formation of a reaction film prevents the generation of hydrogen due to the catalytic action of the new surface.

JP 2000-282178 A Japanese Patent Publication No. 6-89783 JP 2005-112901 A

Nozaki et al., "Brittle Peeling and Long Life of Electrical and Auxiliary Bearings", NTN Technical Review No. 61 (1992), p. 36-39

  In the method described in JP-A-2000-282178, the availability of steel is poor because the specified values of the alloy components are special.

  In the method described in Japanese Patent Publication No. Hei 6-89783, the raceway surface is immersed in a heated treatment solution mainly containing sodium hydroxide to form an iron tetroxide coating on the surface. Since this treatment liquid corresponds to a poisonous substance, the environmental load is high.

  The method described in Japanese Patent Application Laid-Open No. 2005-112901 is effective as a countermeasure for approaching from a lubricant, but may not be applied when the lubricant cannot be changed for the convenience of the user.

  The present invention has been made in view of the above-described problems, and its object is to provide a high degree of freedom in selecting a steel material, a low environmental load, and without using a lubricant, to reduce the life reduction due to early peeling due to hydrogen embrittlement. An object of the present invention is to provide a rolling bearing used for an electric accessory or a continuously variable transmission that can be suppressed.

  The rolling bearing of the present invention is a rolling bearing used for an electric accessory or a continuously variable transmission, and includes an outer ring, an inner ring, and a plurality of rolling elements. The outer race has an outer raceway surface on the inner peripheral surface. The inner ring has an inner ring raceway surface on the outer peripheral surface. The plurality of rolling elements have rolling surfaces that come into contact with the outer raceway surface and the inner raceway surface, and roll between the outer raceway surface and the inner raceway surface. A composite coating mainly composed of molybdenum oxide and molybdate is formed on at least one of the outer raceway surface, the inner raceway surface and the rolling surface.

  According to the rolling bearing of the present invention, by forming the above-described composite coating, it is possible to suppress a decrease in the life due to early peeling due to hydrogen embrittlement that may occur in the electric accessory or the continuously variable transmission. That is, in the rolling bearing of the present invention, the inner ring, the outer ring, the inner ring raceway surface, the outer ring raceway surface or the rolling surface of at least one of the rolling elements has the above-described composite coating on the inner ring raceway surface, compared to the case without the composite coating. In addition, the intrusion of hydrogen into the inner raceway surface, the outer raceway surface or the rolling surface can be suppressed. While the composite coating remains on the inner raceway surface, the outer raceway surface or the rolling surface, a new surface of steel is not exposed due to wear on these surfaces. Therefore, generation of hydrogen by the catalytic action of the new surface and intrusion of the hydrogen into the steel material can be suppressed. As a result, it is possible to prevent a reduction in life due to early peeling due to hydrogen embrittlement.

  Further, even when the composite coating disappears due to wear, molybdenum oxide or molybdate may be mixed in the lubricating oil as wear powder. In this case, similarly to the method disclosed in Japanese Patent Application Laid-Open No. 2005-112901 (Patent Document 3), a reaction film caused by molybdate or the like is formed on a new surface generated during operation. As a result, an effect of suppressing generation and intrusion of hydrogen due to the catalytic action of the new surface can be expected. Such a secondary effect is particularly remarkable when the lubrication method of the bearing is a circulation lubrication method or a grease lubrication method.

  Further, as a method of forming the above-mentioned composite film containing molybdenum oxide and molybdate as main components, any method can be used. For example, a chemical conversion treatment can be used. The treating agent for the chemical conversion treatment is a treating agent containing a molybdic acid component and an aqueous medium. Specifically, the composite film is formed on the surface of the workpiece by immersing the workpiece (the inner ring, the outer ring, and the rolling elements) in the processing agent. Since such a chemical conversion treatment can be applied to general steel materials, it is possible to increase the degree of freedom in selecting a steel material as an object to be processed.

  Furthermore, since the chemical conversion treatment using the above treatment agent does not contain a component corresponding to a poisonous substance, it is superior to the black dyeing treatment in terms of the safety of the treatment operator and the environmental load performance of the treatment agent. . Therefore, the environmental load can be reduced. Therefore, costs required for environmental measures can be reduced, and processing costs can be reduced. As a result, an increase in the manufacturing cost of the rolling bearing can be suppressed.

  The rolling bearing is used in a state where lubricating oil is supplied around a rolling element by a circulating oil supply system. In this case, even when the composite coating is lost due to wear, molybdenum oxide or molybdate is mixed in the lubricating oil as wear powder. For this reason, a reaction film due to molybdate or the like is formed on the new surface generated during operation. As a result, an effect of suppressing generation and intrusion of hydrogen due to the catalytic action of the new surface can be expected.

  The rolling bearing is used in a state where grease is supplied around the rolling element. In this case, even when the composite coating is lost due to abrasion, molybdenum oxide or molybdate is mixed in the grease as abrasion powder. For this reason, a reaction film due to molybdate or the like is formed on the new surface generated during operation. As a result, an effect of suppressing generation and intrusion of hydrogen due to the catalytic action of the new surface can be expected.

  As described above, according to the present invention, an electrical component that has a high degree of freedom in selecting a steel material, has a low environmental load, and can suppress a reduction in life due to early peeling due to hydrogen embrittlement without using a lubricant. A rolling bearing used for an auxiliary machine or a continuously variable transmission can be provided.

FIG. 1 is a schematic sectional view illustrating a configuration of a deep groove ball bearing according to Embodiment 1 of the present invention. FIG. 2 is an enlarged view showing a configuration of a P section in FIG. 1. FIG. 13 is a schematic enlarged cross-sectional view illustrating a configuration of a deep groove ball bearing corresponding to FIG. 2 in Embodiment 2 of the present invention. It is a schematic sectional view showing the composition of the deep groove ball bearing in Embodiment 3 of the present invention. FIG. 14 is a schematic sectional view illustrating a configuration of a deep groove ball bearing according to Embodiment 4 of the present invention. FIG. 13 is a schematic cross-sectional view illustrating a configuration of an electric accessory according to Embodiment 3 of the present invention. FIG. 13 is a schematic sectional view illustrating a configuration of a continuously variable transmission according to a fourth embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

(Embodiment 1)
First, a configuration of a rolling bearing as an example of a rolling device according to an embodiment of the present invention will be described. The rolling bearing is used for an electric accessory or a continuously variable transmission. In this embodiment, a deep groove ball bearing will be described as an example of a rolling bearing.

  With reference to FIG. 1, a deep groove ball bearing 1 of the present embodiment is arranged between an annular outer ring 11, an annular inner ring 12 arranged inside the outer ring 11, and between the outer ring 11 and the inner ring 12, A plurality of balls 13 as rolling elements held by an annular retainer 14 are provided. The outer race 11 has an outer raceway surface 11A on the inner peripheral surface. The inner race 12 has an inner raceway surface 12A on the outer peripheral surface. That is, an outer raceway surface 11A is formed on the inner peripheral surface of the outer race 11, and an inner raceway surface 12A is formed on the outer peripheral surface of the inner race 12. The outer race 11 and the inner race 12 are arranged so that the outer raceway 11A and the inner raceway 12A face each other.

  Further, the plurality of balls 13 are configured to roll between the outer raceway surface 11A and the inner raceway surface 12A. The plurality of balls 13 contact the outer raceway surface 11A and the inner raceway surface 12A on the ball rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by the retainer 14, so that the balls 13 roll on the annular raceway. It is movably held. The entire surface of the ball 13 is a ball rolling surface 13A. With the above configuration, the outer ring 11 and the inner ring 12 of the deep groove ball bearing 1 can rotate relative to each other.

  A grease composition (not shown) is sealed in a space between the outer ring 11 and the inner ring 12, more specifically, a raceway space that is a space between the outer raceway surface 11A and the inner raceway surface 12A. The grease composition forms an oil film between each of the outer ring 11 and the inner ring 12 and the ball 13.

  With reference to FIG. 2, the outer race 11, the inner race 12, and the balls 13 as rolling components constituting the deep groove ball bearing 1 will be described. Ball 13 as a second rolling member is in contact with each of outer ring 11 and inner ring 12 as a first rolling member. The outer ring 11, the inner ring 12, and the balls 13 are all made of high carbon chromium bearing steel specified in JIS G 4805: 2008 of the JIS standard. Each of the outer ring 11, the inner ring 12, and the balls 13 is tempered after quenching.

  The surfaces of the rolling portions of the outer ring 11 and the inner ring 12 are subjected to a chemical conversion treatment after a tempering treatment. By the chemical conversion treatment, a composite coating mainly composed of molybdenum oxide and molybdate is formed on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12. The composite coating mainly composed of molybdenum oxide and molybdate is formed on at least a part of the surfaces of the rolling portions of the outer ring 11 and the inner ring 12. It is preferable that the composite coating mainly composed of molybdenum oxide and molybdate is formed on all the surfaces of the rolling portions of the outer ring 11 and the inner ring 12.

  The rolling portion of the outer race 11 is a region including the outer raceway surface 11A, and the surface of the rolling portion of the outer race 11 forms the outer raceway surface 11A. A composite coating 11B is formed on the surface of the rolling portion of the outer race 11. The rolling portion of the inner ring 12 is a region including the inner ring raceway surface 12A, and the surface of the rolling portion of the inner ring 12 forms the inner ring raceway surface 12A. A composite coating 12B is formed on the surface of the rolling portion of the inner race 12. The rolling portion of the ball 13 is a region including the ball rolling surface 13A, and the surface of the rolling portion of the ball 13 forms the ball rolling surface 13A.

  The value of the oil film parameter に お け る in the region between the outer ring 11 and the ball 13 and the region between the inner ring 12 and the ball 13 is 1.2 or less. The oil film parameter Λ is the ratio between the oil film thickness and the surface roughness.

  Subsequently, formation of a composite coating containing molybdenum oxide and molybdate as main components will be described.

  The treating agent for the chemical conversion treatment performed to form a composite film containing molybdenum oxide and molybdate as main components is an agent containing a molybdic acid component and an aqueous medium.

  The method of forming a composite film containing molybdenum oxide and molybdate as a main component using these treatment agents is performed by chemical conversion treatment, and specifically, immersing the object to be treated in the treatment agents described above. Thus, the above-mentioned composite coating is formed on the surface of the agent to be treated.

  Since the above-mentioned treating agent does not contain a component corresponding to poisonous substances and phosphorus, the safety of the treating worker and the environmental load performance of the treating agent are superior to the blackening treatment and the phosphate treatment.

Next, the effect of this Embodiment is demonstrated.
According to the deep groove ball bearing 1 of the present embodiment, the composite coatings 11B and 12B containing molybdenum oxide and molybdate as main components are formed on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12. For this reason, it is possible to suppress a decrease in the life of the deep groove ball bearing 1 used in the electric accessory or the continuously variable transmission due to the early peeling due to the hydrogen embrittlement. Since the above-described composite coatings 11B and 12B are formed, the intrusion of hydrogen into the inner raceway surface 12A and the outer raceway surface 11A can be suppressed as compared with a case where the composite coatings 11B and 12B are not provided. While the composite coatings 11B and 12B remain on the outer raceway surface 11A and the inner raceway surface 12A, a new surface of steel is not exposed due to wear on these surfaces. Therefore, generation of hydrogen by the catalytic action of the new surface and intrusion of the hydrogen into the steel material can be suppressed. As a result, it is possible to suppress a reduction in life due to early peeling due to hydrogen embrittlement. As described above, the deep groove ball bearing 1 according to the present embodiment can suppress the life reduction due to the early peeling due to the hydrogen embrittlement, and therefore, the electrical accessory or the continuously variable transmission in which the early peeling due to the hydrogen embrittlement is likely to occur. It is particularly advantageously applied to

  Furthermore, even when the composite coatings 11B and 12B have disappeared due to abrasion, molybdenum oxide or molybdate may be mixed in the grease as abrasion powder. In this case, a reaction film due to molybdate or the like is formed on the new surface generated during operation. As a result, an effect of suppressing generation and intrusion of hydrogen due to the catalytic action of the new surface can be expected.

  In this way, it is possible to suppress a reduction in the life of the deep groove ball bearing 1 due to surface damage of the rolling portions of the outer ring 11, the inner ring 12, and the balls 13. Therefore, a long life of the deep groove ball bearing 1 can be realized. Further, a composite coating mainly composed of molybdenum oxide and molybdate is formed on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12. Therefore, the environmental load can be reduced, for example, as compared with the blackening treatment or the treatment for forming a phosphate film, which has a high environmental load.

  Further, the composite coatings 11B and 12B are formed by a chemical conversion treatment in which the outer ring 11 and the inner ring 12 as objects to be processed are immersed in a processing agent. Since such a chemical conversion treatment can be applied to general steel materials, it is possible to increase the degree of freedom in selecting a steel material as an object to be processed.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. Unless otherwise specified, the deep groove ball bearing 1 of the present embodiment has the same configuration as the deep groove ball bearing 1 of the above-described first embodiment, and therefore, description thereof will not be repeated.

  Referring to FIG. 3, deep groove ball bearing 1 according to Embodiment 2 of the present invention has a ball rolling surface 13A on which a composite coating 13B mainly composed of molybdenum oxide and molybdate is formed, while outer ring 11 is formed. The inner ring 12 has no composite coating. In this point, the deep groove ball bearing 1 of the present embodiment is different from the deep groove ball bearing 1 of the first embodiment.

  According to the deep groove ball bearing 1 of the present embodiment, the deep groove ball bearing 1 is applied to an electric accessory or a continuously variable transmission, and the lubrication state between each of the outer ring 11 and the inner ring 12 and the ball 13 is poor. Even if the deep groove ball bearing 1 is used under the condition that the oil film forming property is poor, it is possible to suppress the occurrence of early peeling due to hydrogen embrittlement. Thereby, long life of the deep groove ball bearing 1 can be realized.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. Unless otherwise specified, the deep groove ball bearing 1 of the present embodiment has the same configuration as the deep groove ball bearing 1 of the above-described first embodiment, and therefore, description thereof will not be repeated.

  Referring to FIG. 4, deep groove ball bearing 1 according to Embodiment 3 of the present invention is used in a state where lubricating oil is supplied around balls 13 by a circulating oil supply method. The lubricating oil is circulated by the circulating oil supply means 20. The circulating oil supply means 20 includes a pump 21 and a pipe 22. Lubricating oil is supplied to the deep groove ball bearing 1 through a pipe 22 by a pump 21. The lubricating oil supplied to the deep groove ball bearing 1 returns to the pump 21 through the pipe 22. Thus, the lubricating oil is circulated by the circulating oil supply means 20.

Next, the operation and effect of the deep groove ball bearing 1 according to the present embodiment will be described.
In the deep groove ball bearing 1 of the present embodiment, the same effects as those of the deep groove ball bearing 1 shown in FIGS. 1 and 2 can be obtained. Further, since the lubricating oil is supplied around the balls 13 by a circulating lubrication method, even when the composite coatings 11B and 12B disappear due to wear, molybdenum oxide and molybdate are contained in the lubricating oil as wear powder. Mixed. For this reason, a reaction film due to molybdate or the like is formed on the new surface generated during operation. As a result, an effect of suppressing generation and intrusion of hydrogen by the catalytic action of the new surface can be obtained.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. Unless otherwise specified, the deep groove ball bearing 1 of the present embodiment has the same configuration as the deep groove ball bearing 1 of the above-described first embodiment, and therefore, description thereof will not be repeated.

  The configuration of the rolling bearing according to the present embodiment will be described with reference to FIG. FIG. 5 shows a schematic cross-sectional view of a deep groove ball bearing 1 which is an example of a rolling bearing. The deep groove ball bearing 1 shown in FIG. 5 basically has the same configuration as the deep groove ball bearing 1 shown in FIGS. 1 and 2, but the outer ring 11, the inner ring 12, and the ball 13 are all provided with molybdenum oxide. The deep groove ball bearing 1 shown in FIGS. 1 and 2 is characterized in that composite coatings 11B, 12B, and 13B containing molybdate as a main component are formed, and that a seal member 6 for enclosing grease 7 is provided. Is different from The seal member 6 seals the openings at both axial ends between the inner ring 12 and the outer ring 11. Grease 7 is sealed in the bearing space sealed by the seal member 6. As the grease 7 sealed around the ball 13, a known grease for a rolling bearing can be used.

Next, the operation and effect of the deep groove ball bearing 1 according to the present embodiment will be described.
In the deep groove ball bearing 1 shown in FIG. 5, the same effects as those of the deep groove ball bearing 1 shown in FIGS. 1 and 2 can be obtained. Furthermore, since the grease 7 is sealed in the bearing space by the seal member 6, even if the composite coatings 11B, 12B, and 13B disappear due to wear, molybdenum oxide and molybdate are mixed into the grease 7 as wear powder. . For this reason, a reaction film due to molybdate or the like is formed on the new surface generated during operation. As a result, an effect of suppressing generation and intrusion of hydrogen by the catalytic action of the new surface can be obtained.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described. Unless otherwise specified, the deep groove ball bearing 1 of the present embodiment has the same configuration as the above-described deep groove ball bearing 1 of the fourth embodiment, and therefore, description thereof will not be repeated. FIG. 6 is a cross-sectional view schematically showing a configuration of an electric accessory to which the rolling bearing according to the embodiment of the present invention is applied. Referring to FIG. 6, an alternator 200 will be described as an example of an electrical accessory to which the rolling bearing of the present embodiment is applied.

  As shown in FIG. 6, the alternator 200 according to the present embodiment includes a shaft 201, a rotor 202, a stator 203, a pulley 204, a housing 205, a grease-enclosed deep groove ball bearing 1 which is a rolling bearing for an alternator. Mainly.

  A housing 205 is arranged so as to surround the rotor 202. The shaft 201 is arranged so as to penetrate the center of the rotor 202 and penetrate the wall surface of the housing 205. A stator 203 is disposed inside the housing 205 so as to face the outer peripheral surface of the rotor 202.

  The housing 205 is arranged so as to face a part of the outer peripheral surface at one end of the shaft 201. A grease-enclosed deep groove ball bearing 1, which is a rolling bearing for an alternator, is disposed between the shaft 201 and the housing 205. The shaft 201 is rotatably supported by the housing 205 by the grease-enclosed deep groove ball bearing 1. A pulley 204 having an annular shape is attached to the tip of one end of the shaft 201 outside the housing 205. An engagement groove 206 on which a transmission belt (not shown) is hung is provided on the outer peripheral surface of the pulley 204.

  The grease-enclosed deep groove ball bearing 1, which is a rolling bearing for an alternator, is arranged adjacent to a shaft 201 that is rotationally driven by this power in an alternator 200 that operates using power generated by a power source such as an engine (not shown). For example, a rolling bearing for an electric auxiliary device for an automobile, which is rotatably supported by a housing 205.

  In general, the grease-enclosed deep groove ball bearing 1 disposed at one end of the shaft 201 between the rotor 202 and the pulley 204 is called a front bearing. The grease-enclosed deep groove ball bearing 1 arranged at the other end of the shaft 201 is called a rear bearing. Hydrogen embrittlement is more likely to occur in the grease-filled deep groove ball bearing 1 of the front bearing, which has a large stress such as bending moment, than in the grease-filled deep groove ball bearing 1 of the rear bearing.

  Next, the operation of the alternator 200 will be described. A transmission belt (not shown) that is rotated by power from a power source such as an engine (not shown) is hung on the outer peripheral surface of the pulley 204 in which the engagement groove 206 is formed. As the transmission belt rotates, the pulley 204 rotates around the axis of the shaft 201 integrally with the shaft 201 supported by the grease-enclosed deep groove ball bearing 1 with respect to the housing 205. The rotor 202 rotates around the axis of the shaft 201 integrally with the shaft 201. At this time, the rotor 202 faces the outer peripheral surface of the rotor 202 and relatively rotates with respect to the stator 203 fixed to the housing 205. As a result, an electromotive force is generated in the coils of the stator 203 by the electromagnetic induction between the rotor 202 and the stator 203.

  Rolling bearings for alternators are liable to undergo early peeling due to hydrogen embrittlement due to the effect of slippage between contact elements under sudden acceleration / deceleration conditions. In addition, early peeling due to hydrogen embrittlement may occur due to the influence of energization. Further, with the recent space saving, a belt for driving electrical accessory parts including an alternator has been made serpentine. Here, serpentine means that a plurality of accessory parts are driven by one belt. The use of serpentine eliminates the need for a separate belt for each accessory part, thereby saving space. With serpentine, the applied load tends to increase and the load variation tends to increase, so that slippage is more likely to be induced than in the prior art.

  The grease-enclosed deep groove ball bearing 1, which is a rolling bearing for an alternator, is used for the rotation of the inner ring, and therefore, the load rotation of a part of the outer ring 11 is large. Therefore, early peeling due to hydrogen embrittlement is likely to occur in a part of the outer ring 11, so that the rolling bearing of the present embodiment is preferably applied to the outer ring 11.

Next, the effect of this Embodiment is demonstrated.
In the deep groove ball bearing 1 of the present embodiment, the same effects as those of the deep groove ball bearing 1 according to the fourth embodiment can be obtained. Further, according to the deep groove ball bearing 1 of the present embodiment, as shown in FIG. 6, the shaft 201 of the alternator 200 and the housing 205 arranged to face the outer peripheral surface of the shaft 201 are further provided. The housing 201 may be rotatably supported with respect to the housing 205. As a result, early peeling due to hydrogen embrittlement can be suppressed, so rolling bearings for alternators that have a long service life even under severe operating conditions such as conditions where water is mixed into the bearing, conditions involving slippage, and conditions where electricity occurs occur. Can be provided. Provide rolling bearings for alternators with a long life by suppressing early peeling due to hydrogen embrittlement under use conditions where early peeling due to hydrogen embrittlement is likely to occur, especially under conditions of sudden acceleration / deceleration. can do. Further, it is possible to suppress early peeling due to hydrogen embrittlement even under conditions in which slippage is induced by an increase in load and an increase in load fluctuation accompanying serpentine, so that a long-life rolling bearing for an alternator is provided. Can be.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described. Unless otherwise specified, the deep groove ball bearing 1 of the present embodiment has the same configuration as the above-described deep groove ball bearing 1 of the fourth embodiment, and therefore, description thereof will not be repeated. FIG. 7 is a sectional view schematically showing a configuration of a continuously variable transmission to which the rolling bearing according to the embodiment of the present invention is applied. Referring to FIG. 7, a belt-type continuously variable transmission 240 will be described as an example of the continuously variable transmission to which the rolling bearing of the present embodiment is applied.

  As shown in FIG. 7, the belt-type continuously variable transmission 240 in the present embodiment includes a primary pulley shaft (pulley shaft) 241, a primary pulley 242, a secondary pulley shaft 243, and a secondary pulley (pulley shaft) 244. , An endless belt 245, a casing (housing) 246, and a grease-enclosed deep groove ball bearing 1, which is a rolling bearing for a continuously variable transmission.

  A primary pulley 242 is provided on the primary pulley shaft 241. The primary pulley 242 has a primary pulley fixed sheave 242a and a primary pulley movable sheave 242b. The primary pulley fixing sheave 242a is formed integrally with the primary pulley shaft 241. The primary pulley movable sheave 242 b is penetrated by the primary pulley shaft 241, and is configured to be slidable in the axial direction of the primary pulley shaft 241. One end of the primary pulley shaft 241 is connected to a clutch (not shown). The other end of the primary pulley shaft 241 is rotatably supported by a grease-enclosed deep groove ball bearing 1 which is a rolling bearing for a continuously variable transmission fixed to a casing 246.

  A secondary pulley 244 is provided on the secondary pulley shaft 243. The secondary pulley 244 has a secondary pulley fixed sheave 244a and a secondary pulley movable sheave 244b. The secondary pulley fixing sheave 244a is formed integrally with the secondary pulley shaft 243. The secondary pulley movable sheave 244b is penetrated by the secondary pulley shaft 243, and is configured to be slidable in the axial direction of the secondary pulley shaft 243. One end of the secondary pulley shaft 243 to which a gear of a gear mechanism (not shown) is attached is supported by another bearing. The other end of the secondary pulley shaft 243 is rotatably supported by a grease-enclosed deep groove ball bearing 1 which is a rolling bearing for a continuously variable transmission fixed to a casing 246.

  A V-shaped endless belt 245 is stretched between the primary pulley 242 and the secondary pulley 244. The primary pulley 242 is configured such that the width (primary pulley width) between the primary pulley fixed sheave 242a and the primary pulley movable sheave 242b can be changed by sliding the primary pulley movable sheave 242b.

  The secondary pulley 244 is configured such that the width (secondary pulley width) between the secondary pulley fixed sheave 244a and the secondary pulley movable sheave 244b can be changed by sliding the secondary pulley movable sheave 244b. When the primary pulley width and the secondary pulley width vary, the primary pulley 242 and the secondary pulley 244 are configured such that the respective radial positions where the endless belt 245 is stretched vary.

  Next, the operation of the belt-type continuously variable transmission 240 will be described. Driving force is transmitted to the primary pulley shaft 241 from an engine (not shown) via a clutch. By changing the primary pulley width and the secondary pulley width, the respective radial positions where the endless belt 245 is stretched are changed. As a result, the driving force of the primary pulley shaft 241 is transmitted to the secondary pulley shaft 243 at a continuously variable speed. Driving force is transmitted from the secondary pulley shaft 243 to the axle via a gear mechanism and a differential. Thereby, a continuously variable transmission is achieved.

  For rolling bearings for continuously variable transmissions, it is important to suppress the backlash (axial clearance) of the bearing in order to ensure the rotational accuracy of the pulley. Conventionally, the groove curvature of the inner and outer rings of the bearing was reduced, Techniques have been adopted to reduce axial clearance. However, when the groove curvature of the bearing inner and outer rings is set to be small, the differential slip during the operation of the bearing increases, and as a result, early peeling due to hydrogen embrittlement tends to occur.

  The grease-enclosed deep groove ball bearing 1, which is a rolling bearing for a continuously variable transmission, is used for rotation of the inner ring, so that a part of the outer ring 11 rotates a lot of load. Therefore, early peeling due to hydrogen embrittlement easily occurs in a part of the outer ring 11, and therefore, it is preferable that the bearing member of the present embodiment is applied to the outer ring 11.

Next, the effect of this Embodiment is demonstrated.
In the deep groove ball bearing 1 of the present embodiment, the same effects as those of the deep groove ball bearing 1 according to the fourth embodiment can be obtained. Further, according to the deep groove ball bearing 1 of the present embodiment, as shown in FIG. 7, the pulley shaft 241 of the continuously variable transmission 240 and the casing 246 arranged to face the outer peripheral surface of the pulley shaft 241 are provided. And the pulley shaft 241 may be rotatably supported with respect to the casing 246. As a result, early peeling due to hydrogen embrittlement can be suppressed, so it can be used for continuously variable transmissions that have a long life even under severe use conditions such as conditions where water is mixed in bearings, conditions involving slippage, and conditions where electricity is generated. A rolling bearing can be provided. Also, since the groove curvature of the bearing inner and outer rings is set small to suppress the axial clearance of the bearing, even under conditions where the differential slip during the operation of the bearing becomes large, early peeling due to hydrogen embrittlement can be suppressed, so a long life A rolling bearing for a continuously variable transmission can be provided.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Reference Signs List 1 deep groove ball bearing, 6 sealing material, 7 grease, 11 outer ring, 11A outer ring raceway surface, 11B, 12B, 13B composite coating, 12 inner ring, 12A inner ring raceway surface, 13 balls, 13A ball rolling surface, 14 cage, 20 Circulating oil supply means, 200 alternator, 240 continuously variable transmission.

Claims (3)

A rolling bearing used for an electric accessory or a continuously variable transmission,
An outer ring having an outer ring raceway surface on an inner peripheral surface,
An inner ring having an inner ring raceway surface on an outer peripheral surface,
A plurality of rolling elements having a rolling surface that comes into contact with the outer raceway surface and the inner raceway surface, and rolling between the outer raceway surface and the inner raceway surface,
A rolling bearing, wherein at least one of the outer raceway surface, the inner raceway surface, and the rolling surface is formed with a composite coating mainly composed of molybdenum oxide and molybdate.   The rolling bearing according to claim 1, wherein the rolling bearing is used in a state where lubricating oil is supplied around the rolling element by a circulating oil supply system.   The rolling bearing according to claim 1, wherein the rolling bearing is used in a state where grease is supplied around the rolling element.

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