JP2011202735A - Roller bearing, electric motor equipped with the same, and generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roller bearing further improved in corrosion resistance to electrolytic corrosion, and an electric motor equipped with the roller bearing and a generator.SOLUTION: The rolling bearing 1 includes an inner ring 2, an outer ring 3, a plurality of rolling elements 4 interposed between the inner ring 2 and the outer ring 3; an insulating coating 9A provided at least at one of an inside fitting surface of the inner ring 2 and an outside fitting surface of the outer ring 3; and a conductive means for relieving current concentration on contact parts between the plurality of rolling elements 4 and the inner ring 2 and on contact parts between the plurality of rolling elements 4 and the outer ring 3. The conductive means preferably includes conductive grease 7 serving as a conductive lubricant for lubricating the contact parts between the plurality of rolling elements 4 and the inner ring 2 and the contact parts between the plurality of rolling elements 4 and the outer ring 3. Further preferably, the conductive means further includes a seal member 6 for sealing the conductive lubricant between the inner ring 2 and the outer ring 3 together with the plurality of rolling elements 4. The seal member 6 is conductive and makes the inner ring 2 and the outer ring 3 electrically conductive.

Description

  The present invention relates to a rolling bearing, an electric motor including the same, and a generator.

  Electrocorrosion due to leakage current may occur in bearings used in electric equipment such as motors and generators.

  Japanese Patent Laying-Open No. 2008-69925 (Patent Document 1) discloses a technique for preventing electrolytic corrosion in a bearing used in a wind power generator as one of such devices.

  Wind power generators are often operated unattended from the standpoint of efficiency and profitability, or are increased in size and installed in high places. For this reason, it is desired that the bearing for the wind turbine main shaft used in the wind turbine generator should be maintenance-free and be a simple bearing on the lubrication surface.

  In recent years, there are few places on land that satisfy the installation conditions of wind turbines for wind power generation. For this reason, recently, large-scale wind turbines are often installed on the coastal coast or on the ocean. In this case, wind power generators installed on coastal coasts, etc. are not only lightning to lightning rods due to salt damage, but also increase the possibility of lightning to the rotor and nacelle. There is.

  The electric corrosion generated in the rotating part of the wind turbine generator can be caused not only by the current caused by the lightning strike as described above, but also by the axial current generated in the generator. Therefore, the bearing of the wind turbine generator is required to have extremely high insulation performance. Various insulating film forming methods (for example, using a resin material or a ceramic material) have been proposed.

  In Japanese Patent Application Laid-Open No. 2008-69925 (Patent Document 1), the insulating coating is a thermal spray coating using a ceramic material.

  On the other hand, electrical components and accessories in automobiles, motors in industrial machines, and the like are required to be downsized, high performance, and high output year by year, and usage conditions are becoming stricter.

  The ratio of inverter motors is increasing due to convenience of inverter control (simplification of maintenance and inspection, speeding up, variable handling, etc.), and this increase is expected to continue. Inverter control adjusts voltage and frequency, and a rolling bearing incorporated in an inverter drive motor may be damaged by electric corrosion on the raceway surface or the like due to high-frequency current flowing from the inverter circuit.

  Japanese Patent Application Laid-Open No. 2008-121748 (Patent Document 2) also considers imparting conductivity to grease as another method for preventing electric corrosion of a bearing by a motor or the like in an automobile.

JP 2008-69925 A JP 2008-121748 A JP 2008-67547 A

Yoshihiko Okuyama, Hideki Fujii, “Axial Voltage of Inverter Driven Induction Motor”, Fuji Times, Fuji Electric Co., Ltd., February 1999, Vol. 72, No. 2, p144-149

  In Japanese Patent Application Laid-Open No. 2008-69925 (Patent Document 1), the insulating coating is made of a thermal spray coating using a ceramic material so that no current flows through the bearing. On the other hand, in Japanese Patent Application Laid-Open No. 2008-121748 (Patent Document 2), an electric current is positively supplied to the bearing.

  As described above, in order to prevent the electrolytic corrosion of the bearing, there are two methods in which the current flowing through the bearing is interrupted or the current is passed through the bearing so that the current does not concentrate on the rolling elements of the bearing. .

  Therefore, it has been considered that there is no advantage in introducing conductive grease into the bearing while the insulating coating is applied to the bearing.

  An object of the present invention is to provide a rolling bearing having further improved corrosion resistance against electric corrosion, and an electric motor and a generator including the rolling bearing.

  In summary, the present invention is a rolling bearing, and includes at least one of an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, an inner fitting surface of the inner ring, and an outer fitting surface of the outer ring. Insulating coating provided on either side, and conductive means for alleviating current concentration in contact portions between the plurality of rolling elements and the inner ring and contact portions between the plurality of rolling elements and the outer ring.

  Preferably, the conductive means includes a conductive lubricant that lubricates the contact portions between the plurality of rolling elements and the inner ring and the contact portions between the plurality of rolling elements and the outer ring.

  More preferably, the conductive means further includes a seal portion for enclosing the conductive lubricant between the inner ring and the outer ring together with the plurality of rolling elements. The seal portion is conductive and electrically connects the inner ring and the outer ring.

  More preferably, the conductive lubricant includes a base oil and a thickener, and the thickener includes at least one of carbon black, silver, and nickel.

  Preferably, the conductive means includes a seal portion for enclosing the lubricant between the inner ring and the outer ring together with the plurality of rolling elements. The seal portion is conductive and electrically connects the inner ring and the outer ring.

  Preferably, the inner ring and the outer ring are fitted to the shaft and the housing of the wind power generator. The insulating coating blocks a direct current component of the shaft current flowing between the shaft of the wind power generator and the housing.

In another aspect, the present invention is an electric motor using any one of the rolling bearings described above.
Moreover, this invention is a generator which used one of the said rolling bearings in the further another situation.

  ADVANTAGE OF THE INVENTION According to this invention, the corrosion resistance with respect to electrolytic corrosion can be improved in the rolling bearing used for apparatuses, such as an electric motor and a generator.

It is a figure which shows the structure of the motor which uses the rolling bearing of Embodiment 1. FIG. It is sectional drawing which expands and shows the deep groove ball bearing used for FIG. It is the figure which showed the equivalent circuit of the bearing part with respect to the electric current containing an alternating current component. It is a figure for demonstrating the current concentration in case the grease of a bearing is not made conductive. It is a figure for demonstrating relaxation of the current concentration at the time of making grease of a bearing conductive. It is the figure which showed the 1st modification of the rolling bearing of Embodiment 1. FIG. It is the figure which showed the 2nd modification of the rolling bearing of Embodiment 1. FIG. It is sectional drawing of the rolling bearing of Embodiment 2. It is sectional drawing to which the rolling bearing shown in FIG. 8 was expanded. It is the figure which showed the 1st modification of the rolling bearing of Embodiment 2. FIG. It is the figure which showed the 2nd modification of the rolling bearing of Embodiment 2. FIG. FIG. 10 is a diagram for illustrating a first modification example of the second embodiment. FIG. 10 is a diagram for describing a second modification of the second embodiment. It is a figure for demonstrating the wind power generator which is an example of the use for which this invention is used suitably. It is the figure which expanded the nacelle part of the wind power generator of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a diagram showing a configuration of a motor using the rolling bearing of the first embodiment. The lower half of FIG. 1 is a side view, and the upper half is a cross-sectional view taken along a plane passing through the axial center.

  With reference to FIG. 1, a motor 10 has a rotor 13 attached to a main shaft 11. A pulley 17 is attached to one end of the main shaft 11 and a belt 18 for rotating an air conditioning fan or the like is attached. The motor 10 rotates a load by attaching a belt 18 to a pulley 17 interlocked with the main shaft 11.

  The main shaft 11 is rotatably supported on the flange 14 by radial ball bearings 15 and 16 (motor bearings) attached to both ends of the rotor 13. A stator 12 is fixed to the flange 14 so as to face the rotor 13. A preload is applied by a wave spring washer or the like located between the flange 14 and the radial ball bearing 16.

  The radial ball bearing 15 and the radial ball bearing 16 are formed by an inner ring as an inner member, an outer ring as an outer member, a plurality of balls as rolling elements, and a cage that holds the plurality of balls. The center line passing through the center of the ball is in a state in which the main shaft 11 is applied with a radial load by the belt 18 and the strain reaches the inner ring of the bearing so that the load sharing of the ball is inclined with respect to the vertical contact surface. .

  In the present embodiment, deep groove ball bearings are used as the radial ball bearing 15 and the radial ball bearing 16. In addition to the deep groove ball bearing, for example, an angular ball bearing or a cylindrical roller bearing can be used.

FIG. 2 is an enlarged cross-sectional view of the deep groove ball bearing used in FIG.
Referring to FIG. 2, in the deep groove ball bearing 1, an inner ring 2 having an inner ring raceway surface 2A on an outer peripheral surface and an outer ring 3 having an outer ring raceway surface 3A on an inner peripheral surface are arranged concentrically, and the inner ring raceway surface 2A and the outer ring A plurality of rolling elements 4 are arranged between the raceway surface 3A. A retainer 5 that holds the plurality of rolling elements 4 and a seal member 6 that is fixed to the outer ring 3 and the like are provided in each of the axially opposite end openings 8A and 8B of the inner ring 2 and the outer ring 3. Conductive grease 7 is sealed at least around the rolling element 4.

  In the deep groove ball bearing 1, an insulating coating 9A is formed on the outer peripheral surface of the outer ring 3 as shown in FIG. In the present invention, the outer peripheral surface of the outer ring 3 forming the insulating coating 9A includes at least a surface in a range where the outer ring 3 is in contact with the housing (the flange 14 in FIG. 1) that holds the outer ring 3.

  A method for forming the insulating coating 9A on the outer peripheral surface of the outer ring will be briefly described. An insulating coating 9A is formed on the outer peripheral surface of the outer ring 3 by thermal spraying. The insulating coating 9A is, for example, a ceramic coating, and a thermal spray material such as oxide ceramics or carbide cermet is formed on the surface of a base metal such as steel by a known thermal spraying method.

  Examples of the oxide ceramic used as the thermal spray material include alumina, zirconia, and titania, and examples of the carbide cermet include chromium carbide and tungsten carbide.

  In forming the thermal sprayed ceramic coating, a metal powder such as nickel can be sprayed on the lowermost layer in order to improve the adhesion between the thermal spray coating and the base metal. Moreover, a metal film can be formed in the outermost layer for the purpose of relieving the external mechanical impact which a thermal spraying ceramic film receives.

  As the spraying method, for example, a plasma spraying method, a high-speed gas flame spraying method, or the like can be used. The film thickness of the thermal spray coating can be appropriately set according to the type of the thermal spray material and the use of the resulting thermal spray coating coating member. Usually, when the thermal spray material is alumina and the thermal spray material is 20 to 20 It is about 2000 micrometers, Preferably it is about 50-1000 micrometers.

  Even if the insulating coating is other than the ceramic sprayed coating, it is sufficient if the insulating property can be ensured, for example, it may be resinous. When the insulating coating is formed of resin, other methods may be used. For example, the resin coating having a desired thickness and shape may be formed by injection molding with the outer ring or the inner ring as a core.

  In addition, the conductive grease is made conductive by mixing the base oil with a powder of carbon black, silver, nickel or the like as a thickener. Carbon black, which is an example of a typical additive, can be added to conductive seals, can be used in a wide range from low to high temperatures, and has excellent heat resistance, cold resistance, and chemical resistance. Can be obtained.

<Examination of the reason for the occurrence of electrolytic corrosion when using non-conductive grease>
In the inverter motor, a high frequency AC voltage is generated. Since it is an alternating current component, even if it is an electrical insulator, a current flows when it acts as a capacitor. “Inverter-driven induction motor shaft voltage”, Yoshihiko Okuyama, Hideki Fujii, Fuji Jiho, Vol.72 No. 2 The details are reported in February 1999, p144-149.

  A similar phenomenon may occur in the generator. In the generator, an inverter is not always used, but when a surge voltage is generated in the field coil, electrostatic coupling between the field coil and the iron core (magnetic path) around which the coil is wound, It is expected that a voltage equivalent to the surge voltage is induced on the rotating shaft of the generator. The voltage induced on the rotating shaft of the generator flows to the housing via the rolling bearing, and electrolytic corrosion occurs on the bearing raceway surface of the rolling bearing.

  As described above, in bearings used in devices such as motors and generators that have a coil and electricity flows through the coil, surge voltage is likely to occur due to a sudden change in current due to current on / off, thereby increasing the frequency. AC voltage is generated.

  Here, even if the outer ring outer diameter portion of the deep groove ball bearing 1 of FIG. 2 has an insulator made of the insulating coating 9A, this also acts as a capacitor, so that an alternating voltage passes therethrough. Even if there is an insulating film of the insulating coating 9A, the AC voltage passes and acts on the grease oil film between the rolling element 4 and the bearing ring in the bearing. Like a ceramic sprayed film, a normal grease oil film is also an insulator, so it does not pass DC components, but allows AC components to pass through it as a capacitor.

FIG. 3 is a diagram showing an equivalent circuit of the bearing portion with respect to a current containing an AC component.
Referring to FIG. 3, capacitors 22, 24, and 26 are connected in series to AC voltage generation source 20. When the node N2 is an outer ring, the capacitor 22 is a ceramic sprayed capacitor that insulates the housing (node N1) and the outer ring (node N2). The capacitor 24 is a capacitor made of a grease oil film that insulates the outer ring (node N2) and the rolling elements (node N3). The capacitor 26 is a capacitor made of a grease oil film that insulates the rolling elements (node N3) and the inner ring (node N4).

  FIG. 4 is a diagram for explaining current concentration when the grease of the bearing is not conductive.

  Referring to FIG. 4, a voltage (potential difference between the rolling element and the raceway surface) is generated on the rolling element 4, the raceway surface 2 </ b> A of the inner ring, and the raceway surface 3 </ b> A of the outer ring by applying an alternating voltage. When this voltage exceeds the pressure resistance of the oil film, sparking occurs between the rolling elements and the raceway surface, and electric corrosion occurs. That is, when the insulation of a portion (for example, a portion where a load is applied) where the pressure resistance of the oil film is the lowest among a plurality of rolling elements is broken, a current flows concentrated on that one point. At this time, a small arc is generated and the raceway surface is damaged. Since concentrated at one point, the current density is high and the track surfaces 2A and 3A are easily damaged. In addition, since the AC voltage is used, the insulation recovery and insulation breakdown of the oil film are repeated, so that sparks are generated many times.

  FIG. 5 is a diagram for explaining relaxation of current concentration when the grease of the bearing is made conductive.

  Referring to FIG. 5, when conductive grease 7 is introduced, alternating current flows through conductive grease 7 in addition to the contact portion when flowing into rolling element 4, so that the current is dispersed. Moreover, as shown in FIG. 4, since it does not concentrate on one point at the moment of dielectric breakdown, it is distributed to a plurality of rolling elements. Therefore, electrolytic corrosion due to AC voltage can be prevented.

[Modification of Embodiment 1]
In the first embodiment, an insulating (resistance) layer such as a ceramic sprayed film is provided on the outer diameter of the outer ring in order to prevent electrolytic corrosion due to a large current such as lightning or to suppress current during electrolytic corrosion due to direct current. This insulating layer may be provided in any part. For example, the ceramic spray coating may be formed on the inner peripheral surface of the inner ring 2 in addition to the outer peripheral surface of the outer ring 3.

FIG. 6 is a view showing a first modification of the rolling bearing of the first embodiment.
In the example shown in FIG. 6, a ceramic coating 9 </ b> B is formed on the inner peripheral surface of the inner ring 2. The inner peripheral surface of the inner ring 2 that forms the ceramic coating 9B includes at least a surface in a range in contact with the main shaft 11 that the inner ring 2 supports. Also in the case shown in FIG. 6, electrolytic corrosion due to alternating current components can be prevented by enclosing the conductive grease 7.

FIG. 7 is a view showing a second modification of the rolling bearing of the first embodiment.
In the example shown in FIG. 7, ceramic coatings 9A and 9B are formed on the outer peripheral surface of the outer ring 3 and the inner peripheral surface of the inner ring 2, respectively. Also in the case shown in FIG. 6, electrolytic corrosion due to alternating current components can be prevented by enclosing the conductive grease 7.

  As described above, according to the first embodiment, by using an insulating film and conductive grease, which seem to contradict each other, the direct current component of lightning and shaft current is cut off and the potential difference between the inner and outer rings is reduced by the alternating current component. Can be effectively prevented.

  That is, by using conductive grease, an effect of suppressing the potential difference between the rolling elements and the raceway surface can be obtained. In this case, alternating current constantly flows, but the current density is small and does not lead to electrolytic corrosion.

  Instead of the conductive grease, a conductive seal may be adopted. That is, it is possible to obtain an effect of suppressing the potential difference between the inner ring and the outer ring by imparting conductivity to the seal member 6 of FIGS. 2, 6, and 7. Since the current between the shaft and the housing mainly flows between the inner and outer rings via the seal, it does not flow much to the rolling elements. For the conductive seal, carbon black, which is a typical conductive material, may be added to the seal member.

  However, it is difficult to maintain the conductivity between the seal lip and the seal groove. In the short term, insulation is caused by the formation of an oil film due to vibration after the oil has entered, and in the long term insulation due to corrosion of the seal groove. It becomes a problem. For this reason, although the cost increases, it is preferable to use a conductive grease and a conductive seal in combination because of high reliability. Even if such a combination is used, there is a merit in terms of cost compared to a bearing that uses ceramic balls as rolling elements.

  Conventionally, in order to prevent electric corrosion of the bearing, only one of two methods of interrupting the current flowing through the bearing or flowing the current through the bearing without concentrating the current on the rolling elements of the bearing is used. Was done. And it was thought that there was no advantage about introducing conductive grease into the bearing while applying the insulating coating to the bearing.

  In the present embodiment, an excellent effect of further improving corrosion resistance against electric corrosion can be obtained by applying a seemingly conflicting process of interrupting current and facilitating current flow to the bearing.

[Embodiment 2]
FIG. 8 is a cross-sectional view of the rolling bearing of the second embodiment.

  Referring to FIG. 8, an insulated rolling bearing 105 according to the second embodiment includes an inner ring 111 and an outer ring 112 that form a pair of race rings, and a plurality of rolling elements 113 that are interposed between the inner ring 111 and the outer ring 112. Have. The insulated rolling bearing 105 may be a radial bearing capable of a thrust load, and may be an angular ball bearing, a tapered roller bearing, a deep groove ball bearing, or the like in addition to the self-aligning roller bearing.

  The outer ring 112 of the insulated rolling bearing 105 has a spherical raceway surface 112A, and each rolling element 113 has a spherical roller with an outer peripheral surface along the outer ring raceway surface 12A. The inner ring 111 has a flanged structure having the raceway surfaces 111A and 111A in each row individually. The rolling elements 113 are held by a holder 114 for each row.

  The outer ring 112 is installed by being fitted to the inner diameter surface of the bearing housing 115. The inner ring 111 is fitted to the outer periphery of the main shaft 103 to support the main shaft 103. The inner ring 111, the outer ring 112, and the rolling elements 113 are formed of a metal material such as bearing steel. The bearing housing 115 is provided with a seal member 116 such as a labyrinth seal between the side wall 115 </ b> A that covers both ends of the insulating rolling bearing 105 and the main shaft 103. Since the sealing performance is obtained by the bearing housing 115, the insulating rolling bearing 105 has a structure without a seal. If it is such a structure, it may be a type in which conductive lubricating oil is circulated through the bearing portion instead of the conductive grease.

FIG. 9 is an enlarged cross-sectional view of the rolling bearing shown in FIG.
Referring to FIG. 8, the insulating rolling bearing 105 has a ceramic spray coating 117 </ b> A formed on the outer peripheral surface 112 </ b> B of the outer ring 112. In this embodiment, the outer peripheral surface 112B of the outer ring 112 forming the ceramic spray coating 117A includes at least a surface in a range where the housing 115 holding the outer ring 112 and the outer ring 112 are in contact with each other. In the case shown in FIG. 9, the outer peripheral surface 112 </ b> B of the outer ring 112 is a surface in the range including the chamfered portion BC in the range from the outer diameter surface BA to the end surface BB of the outer ring 112.

  Also in the second embodiment, the conductive grease 107 similar to that in the first embodiment is filled in the contact portion between the raceway surface and the rolling element.

  Further, the ceramic spray coating may be formed on the inner peripheral surface of the inner ring 111 in addition to the outer peripheral surface 112B of the outer ring 112.

FIG. 10 is a view showing a first modification of the rolling bearing of the second embodiment.
FIG. 11 is a view showing a second modification of the rolling bearing of the second embodiment.

  A modified example of the insulated rolling bearing according to the second embodiment will be described with reference to FIGS. In the example shown in FIG. 10, a ceramic coating 117 </ b> B is formed on the inner peripheral surface 111 </ b> B of the inner ring 111. In the present invention, the inner peripheral surface 111B of the inner ring 111 forming the ceramic coating 117B includes at least a surface in a range in contact with the main shaft 103 supported by the inner ring 111. In the case shown in FIG. 10, the inner peripheral surface 111 </ b> B of the inner ring 111 is a surface in a range including the chamfered portion BF in the range from the inner diameter surface BD to the end surface BE of the inner ring 111.

  In the example shown in FIG. 11, ceramic coatings 117A and 117B are formed on the outer peripheral surface 112B of the outer ring 112 and the inner peripheral surface 111B of the inner ring 111, respectively.

  As described above, the insulating performance is ensured by forming a ceramic sprayed coating on at least one of the surface where the outer ring and the housing contact, and the surface where the inner ring and the shaft contact, and mainly due to the direct current component of the current. Electric corrosion can be prevented.

[Other variations]
FIG. 12 is a diagram for explaining a first modification of the second embodiment.

FIG. 13 is a diagram for explaining a second modification of the second embodiment.
As another example of the insulated rolling bearing, FIG. 12 shows a cross section of an insulated angular contact ball bearing, and FIG. 13 shows a perspective view of the insulated tapered roller bearing.

  12 and 13, the rolling elements 113 and the cage 114 are disposed between the inner ring 111 and the outer ring 112. A ceramic sprayed coating 117A is formed on the outer peripheral surface 112B of the outer ring 112 of each bearing.

  The bearings shown in FIGS. 12 and 13 may be used in place of the bearing 105 in FIG. Even in these bearings, by using the conductive grease 107 together with the insulating ceramic spray coating, the direct current component of the current can be cut off and the current concentration of the alternating current component of the current can be alleviated. The same effect can be achieved.

  In addition, since the conductive grease used for the above embodiment can suppress wear due to electrolytic corrosion, the life of various motors and generator bearings can be improved. This type is also used for ball bearings, cylindrical roller bearings, tapered roller bearings, spherical roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, thrust spherical roller bearings, etc. The invention described in the embodiment can be applied.

[Application example]
FIG. 14 is a diagram for explaining a wind turbine generator that is an example of an application in which the present invention is preferably used.

  As shown in FIG. 14, the wind turbine generator 201 rotatably supports a main shaft 203 to which a blade 202 serving as a windmill is attached by a main shaft bearing 205 installed in a bearing housing in the nacelle 204. A speed increaser 206 and a generator 207 are installed inside. The speed increaser 206 increases the rotation of the main shaft 203 and transmits it to the input shaft of the generator 207. The nacelle 204 is installed on the support base 208 so as to be rotatable through a swivel seat bearing.

FIG. 15 is an enlarged view of the nacelle portion of the wind turbine generator of FIG.
Referring to FIG. 15, wind power generator 201 includes a main shaft 203, a blade 202, a speed increaser 206, a generator 207, a main shaft bearing 205, and a turning motor 209. The nacelle 204 is turned through the speed reducer 210 by driving the turning motor 9. The nacelle 204 is turned in order to make the direction of the blade 202 face the wind direction. In the example of FIG. 15, two bearings for supporting the main shaft are provided, but one bearing may be provided. The speed increaser 206, the generator 207, and the main shaft bearing 205 are stored in the nacelle 204.

  The main shaft 203 enters the nacelle 204, is connected to the input shaft of the speed increaser 206, and is rotatably supported by the main shaft bearing 205. The main shaft 203 transmits the rotational torque generated by the blade 202 receiving wind force to the input shaft of the speed increaser 206. The blade 202 is provided at the tip of the main shaft 203 and converts wind force into rotational torque and transmits it to the main shaft 203.

  The main shaft bearing 205 is fixed in the nacelle 204 and supports the main shaft 203 rotatably. The main shaft bearing 205 is composed of a rolling bearing, for example, a self-aligning roller bearing, a tapered roller bearing, a cylindrical roller bearing, or a ball bearing. These bearings may be single row or double row.

  The speed increaser 206 is provided between the main shaft 203 and the power generator 207, and increases the rotational speed of the main shaft 203 and outputs it to the power generator 207. As an example, the speed increaser 206 is configured by a gear speed increasing mechanism including a planetary gear, an intermediate shaft, a high speed shaft, and the like. Although not particularly illustrated, a plurality of bearings for rotatably supporting a plurality of shafts are also provided in the speed increaser 206. The generator 207 is connected to the output shaft of the speed increaser 206, and generates power by the rotational torque received from the speed increaser 206. The generator 207 is constituted by, for example, an induction generator. A bearing that rotatably supports the rotor is also provided in the generator 207.

  The bearing described in Embodiment 1 or 2 can be suitably used for various bearings used in such a wind turbine generator. Wind power generators are installed in places that are subject to lightning strikes, such as on the mountain or at sea, and there is a high possibility that direct current from lightning strikes the bearings. Furthermore, since the generator 207 is mounted, it is assumed that a current containing an AC component flows not only in the bearing inside the generator 207 but also in other bearing portions. And since a wind power generator is installed in the place where traffic is inconvenient and is a high place, it is difficult to perform maintenance easily.

  Therefore, a bearing having an insulating coating on at least one of the outer ring and the inner ring as shown in the present embodiment and having conductive grease or a conductive seal so as to reduce the potential difference between the inner ring and the outer ring is provided with this bearing. It can use suitably for such a wind power generator.

  Finally, this embodiment will be summarized again using the drawings. 1 and 2, a rolling bearing 1 according to the present embodiment includes an inner ring 2, an outer ring 3, a plurality of rolling elements 4 interposed between the inner ring 2 and the outer ring 3, and an inner side of the inner ring 2. 9A of insulation coating provided in at least any one of a fitting surface and the outer fitting surface of the outer ring | wheel 3, the contact part of the some rolling element 4 and the inner ring 2, and the contact part of the some rolling element 4 and the outer ring | wheel 3 And a conductive means for alleviating current concentration.

  Preferably, the conductive means includes conductive grease 7 which is a conductive lubricant that lubricates the contact portions between the plurality of rolling elements 4 and the inner ring 2 and the contact portions between the plurality of rolling elements 4 and the outer ring 3.

  More preferably, the conductive means further includes a seal member 6 for enclosing the conductive lubricant between the inner ring 2 and the outer ring 3 together with the plurality of rolling elements 4. The seal member 6 is conductive and electrically connects the inner ring 2 and the outer ring 3.

  More preferably, the conductive lubricant includes a base oil and a thickener, and the thickener includes at least one of carbon black, silver, and nickel.

  Preferably, the conductive means includes a seal member 6 for enclosing the lubricant between the inner ring 2 and the outer ring 3 together with the plurality of rolling elements 4. The seal member 6 is conductive and electrically connects the inner ring 2 and the outer ring 3.

  Preferably, the inner ring 2 and the outer ring 3 are fitted to a rotating shaft and a casing of any of the wind power generators 201 as shown in FIGS. 14 and 15. The insulating coating blocks a direct current component of the shaft current flowing between the shaft of the wind power generator 201 and the housing.

  In another aspect, the present invention is an electric motor as shown in FIG. 1 using any one of the rolling bearings described above.

  Moreover, this invention is a generator as shown in FIG. 15 which used one of the said rolling bearings in the further another situation. In addition, if it is a generator with a rotating shaft, this invention can be applied even if it is not based on wind power generation.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  1 deep groove ball bearing, 2,111 inner ring, 3,112 outer ring, 4,113 rolling element, 5,114 cage, 6,116 seal member, 7,107 conductive grease, 8A, 8B axial end openings, 9 , 10 Motor, 9A, 9B, 117A, 117B Ceramic spray coating, 11, 103, 203 Main shaft, 12 Stator, 13 Rotor, 14 Flange, 15, 16 Radial ball bearing, 17 Pulley, 18 Belt, 22, 24, 26, 22, 24, 26 Capacitor, 105 Bearing, 111B Inner peripheral surface, 112B Outer peripheral surface, 115 Bearing housing, 115A Side wall, 201 Wind power generator, 202 Blade, 204 Nacelle, 205 Main shaft bearing, 206 Booster, 207 Power generation Machine, 208 support base, 209 motor for turning, 210 speed reducer.

Claims (8)

Inner ring,
Outer ring,
A plurality of rolling elements interposed between the inner ring and the outer ring;
An insulation coating provided on at least one of the inner fitting surface of the inner ring and the outer fitting surface of the outer ring;
A rolling bearing comprising: a contact portion between the plurality of rolling elements and the inner ring; and a conductive means for relaxing current concentration at a contact portion between the plurality of rolling elements and the outer ring. The conductive means is
The rolling bearing according to claim 1, comprising a conductive lubricant that lubricates a contact portion between the plurality of rolling elements and the inner ring and a contact portion between the plurality of rolling elements and the outer ring. The conductive means is
A seal part for enclosing the conductive lubricant together with the plurality of rolling elements between the inner ring and the outer ring;
The rolling bearing according to claim 2, wherein the seal portion is electrically conductive and electrically connects the inner ring and the outer ring. The conductive lubricant is
Base oil,
A thickener,
The thickener is
The rolling bearing according to claim 2 or 3, comprising at least one of carbon black, silver, and nickel. The conductive means is
Including a seal portion for enclosing a lubricant between the inner ring and the outer ring together with the plurality of rolling elements;
The rolling bearing according to claim 1, wherein the seal portion is electrically conductive and electrically connects the inner ring and the outer ring. The inner ring and the outer ring are fitted to a shaft and a housing of a wind power generator,
The rolling bearing according to claim 1, wherein the insulating coating blocks a direct current component of an axial current flowing between the shaft of the wind turbine generator and the housing.   The electric motor using the rolling bearing of any one of said 1-5.   The generator using the rolling bearing of any one of said 1-5.

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