JP2009270673A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily incorporate a short-circuiting path in a rolling bearing equipped with an electrolytic erosion preventing function. <P>SOLUTION: An inner ring energization face 17 and an outer ring energization face 18 are respectively provided on an outer diameter face 11a and an inner diameter face 12a of an inner ring 11 and an outer ring 12, and minute protrusions are formed on each energization face 17, 18. Cylindrical rollers 23 for energization are interposed between a plurality of balls interposed between the inner ring 11 and the outer ring 12, and they are retained by a common retainer 16. The short-circuiting path is formed by metallic contact of the cylindrical rollers 23 with the energization faces 17, 18. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rolling bearing having an electrolytic corrosion prevention structure.

  In a rolling bearing used for an electric device such as an electric motor, when the grounding is incomplete or a high-frequency current is used, the current of the electric device may flow through the raceway and the rolling element of the rolling bearing. At this time, a phenomenon in which the raceway surface is locally melted by sparks generated in an incomplete portion of the lubricating oil film between the raceway surface of the raceway and the rolling element, so-called galvanic corrosion occurs, and causes a reduction in bearing life. .

  In order to prevent the electrolytic corrosion, it is known to form a ceramic sprayed coating on the outer diameter surface of the outer ring constituting the race (Patent Document 1). It is also known to electrically short-circuit between the inner and outer rings by attaching an energizing brush between the inner and outer rings (Patent Document 2). Further, there is also known one in which a conductive grease is sealed between the inner and outer rings so that a current flowing into the bearing flows through the grease (Patent Document 3).

JP 2005-133876 A (paragraph 0012 of “Best Mode for Carrying Out the Invention”) Utility Model Registration No. 2546472 (paragraph 0007 of “Example”) JP 2007-100006 (paragraph 0032 of “Best Mode for Carrying Out the Invention”)

  As disclosed in Patent Document 1, according to the method of providing a ceramic sprayed coating on the outer diameter surface of the outer ring, the sprayed coating may be destroyed when the outer ring is incorporated into the housing. In addition, when this method is applied to a grease lubricated bearing, the heat dissipation generated by the rotation of the bearing is hindered by the sprayed coating, so that heat cannot be dissipated through the housing, which causes the bearing to be seized.

  Furthermore, the above method requires high processing costs and material costs for thermal spraying the ceramic, and it is necessary to impregnate the pores of the thermal spray coating with a synthetic resin as a countermeasure when cracks occur in the thermal spray coating. There are also problems such as being.

  As disclosed in Patent Document 2, the method of short-circuiting using the energizing brush is concerned that the PV value becomes high due to the sliding contact of the energizing brush, in addition to the problem that hinders the high-speed rotation of the bearing. There is also a problem that the sliding contact sound of the brush occurs.

  As in Patent Document 3, the method of encapsulating conductive grease is not suitable for high-speed rotation because the grease is mixed with a conductive material such as carbon black, and there are problems such as high rotational noise.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art, to provide a rolling bearing which is easy to assemble and has a stable electrolytic corrosion preventing effect.

  In order to solve the above problems, in the present invention, the inner ring 11 and the outer ring 12 constituting the raceway ring, the required number of rolling elements interposed between the inner ring 11 and the outer ring 12, and the rolling elements are held. In the rolling bearing including the cage 16, at least one energizing rolling element is interposed in the rolling element while being held by the cage 16, and the inner ring energizing surface 17 is disposed on the outer diameter surface 11 a of the inner ring 11. The outer ring energizing surface 18 is provided on the inner diameter surface 12a of the outer ring 12, and the energizing rolling element is in metal contact with the inner ring energizing surface 17 and the outer ring energizing surface 18.

  In the rolling bearing having the above-described configuration, the energizing rolling element is in metal contact with the inner ring energizing surface 17 and the outer ring energizing surface 18, so that an electrical short circuit path between the energizing rolling element is provided between the inner ring 11 and the outer ring 12. It is formed.

Since this invention is the above structure, there can exist the following effects.
a) By forming a short-circuit path through the energized rolling element, no current flows through the rolling element that receives the load, and therefore, electrolytic corrosion on the raceway surface is prevented.

  b) Since the energizing rolling element is held by the same cage 16 as the rolling element receiving the load, the energizing rolling element can be easily incorporated into the bearing.

  c) By forming minute projections on the current-carrying surfaces 17 and 18 by the unevenness 19 included in the rough surface left without finishing, a large number of current-carrying surfaces 17 and 18 can be formed on the current-carrying surfaces 17 and 18 without any special processing. Microprojections can be formed.

  d) Stabilization with the current-carrying rolling element over the entire circumference of the current-carrying surfaces 17 and 18 by processing the current-carrying surfaces 17 and 18 and forming dispersed minute projections or a plurality of minute projections 22 on the entire circumference. Contact is obtained.

  e) The structure of the retainer 16 that holds them in common is simplified by configuring the rolling elements that receive a load by the balls 15 and the energizing rolling elements by the cylindrical rollers 23, respectively. Mounting becomes easy. In addition, since the cylindrical roller 23 can sufficiently secure the contact area between the inner and outer ring current-carrying surfaces 17 and 18, a stable electrolytic corrosion preventing effect can be obtained.

  f) Configuration in which circumferential grooves 31 and 32 having a required depth are provided along both sides of the raceways 13 and 14 of the inner and outer rings 11 and 12, and current-carrying surfaces 17 and 18 are formed on the groove bottoms of the circumferential grooves 31 and 32. Since the revolution radius of the cylindrical roller 23 approaches the revolution radius of the ball 15, the peripheral speed difference between the two becomes small, and the vibration applied to the cage 16 is suppressed.

  g) By adopting a configuration in which the cylindrical roller 23 is pressed against the inner ring energizing surface 17 by contact with the bent portion 29 of the cage 16, the cylindrical roller 23 is prevented from being lifted from the inner ring energizing surface 17 by centrifugal force. Energization can be secured.

  Embodiments of the rolling bearing according to the present invention will be described below with reference to the accompanying drawings.

  As shown in FIGS. 1 to 7, the rolling bearing of the first embodiment is interposed between the inner ring 11 and the outer ring 12 that constitute the inner and outer opposed race rings, and between the race 13 of the inner ring 11 and the race 14 of the outer ring 12. The ball 15 includes a required number of balls 15, a current-carrying cylindrical roller 23 interposed between the balls 15, and a cage 16 that holds the ball 15 and the cylindrical roller 23.

  Of the inner ring outer diameter surface 11 a existing on both sides of the raceway 13 of the inner ring 11, a portion having a required width in contact with the raceway 13 is an inner ring energization surface 17. Similarly, the outer ring energizing surface 18 is a portion of the outer ring inner diameter surface 12 a existing on both sides of the raceway 14 of the outer ring 12 and having a required width in contact with the raceway 14. These inner and outer current-carrying surfaces 17 and 18 are formed at positions facing each other in the radial direction.

  In the manufacturing process of the rolling bearing, the raceways 13 and 14 of the inner and outer rings 11 and 12 are superfinished. However, the outer diameter surface 11a and the inner diameter surface 12a on both sides thereof are not subjected to such a finishing process, and are left as a rough surface left after being subjected to heat treatment after the turning process or after being subjected to rough grinding. An infinite number of minute protrusions are formed over the entire circumference by the unevenness 19 (see FIG. 5A) included in the rough surface.

  In some cases, the current-carrying surfaces 17 and 18 are positively processed to form dispersed microprotrusions 20 over the entire circumference (see FIG. 5B).

  As shown in FIG. 1, a total of six balls 15 are used, and each ball 15 is composed of a combination of three cylindrical rollers 23, one between the two balls 15. In the case shown in the drawing, the three cylindrical rollers 23 are uniformly distributed in consideration of the overall balance, but at least one is sufficient from the viewpoint of preventing electrolytic corrosion.

  The balls 15 are interposed between the inner and outer races 13 and 14 and perform the action of rotating under the load as in the case of a normal rolling bearing. The cylindrical roller 23 is made of a metal that is used as a rolling element of a normal cylindrical roller bearing. Here, the cylindrical roller 23 is exclusively used as an energized rolling element. The cylindrical roller 23 is disposed in a direction in which the axis is the axial direction.

  As shown in FIGS. 4 and 6, the cage 16 is provided with a ball holding portion 25 corresponding to the ball 15 and the cylindrical roller 23, and a holding portion 26 is provided. Retained in the part.

  The balls 15 stored and held in the ball holding portion 25 are interposed between the tracks 13 and 14 of the inner and outer rings 11 and 12 (see FIG. 3). The cylindrical roller 23 held by the roller holding portion 26 straddles the raceways 13 and 14, and both end portions thereof are sandwiched between the inner and outer current-carrying surfaces 17 and 18, respectively, and are in contact with both the current-carrying surfaces 17 and 18 (See FIG. 2). Microscopically, both end portions of the cylindrical roller 23 are microprojections formed by the above-described unevenness 19 (see FIG. 5A) formed on the current-carrying surfaces 17 and 18, or microprojections 20 ( Metal contact is made (see FIG. 5B). By the contact, an electrical short circuit path is formed between the inner and outer rings 11 and 12 via the cylindrical roller 23.

  The cylindrical roller 23 tends to be lifted from the inner ring energizing surface 17 under the action of centrifugal force during rotation of the bearing. Therefore, for some cylindrical rollers 23, as shown in FIG. 7, a bent portion 29 is provided in the roller holding portion 26 (see the alternate long and short dash line in FIG. 7), and the bent portion 29 is used as the shoulder portion of the cylindrical roller 23. It is desirable to apply an inward load (see arrow A in FIG. 7) by bringing the cylindrical roller 23 into contact with the inner ring energizing surface 17.

  In this case, when the cylindrical roller 23 is pressed to the inner ring energizing surface 17 side, the cylindrical roller 23 is separated from the outer ring energizing surface 18 on the opposite side, and the energization at this portion may be interrupted. However, the short-circuit path through the cage 16 in contact with the cylindrical roller 23, the cylindrical roller 23 held in another roller holding portion 26 not provided with the bent portion 29, and the outer ring energizing surface 18 in contact with the cylindrical roller 23. Is formed, so there is no problem.

  In addition, conventional seal members 27 and 28 are attached to both end portions of the opposing surfaces of the inner and outer rings 11 and 12, and grease is sealed inside thereof.

  The rolling bearing of Embodiment 1 is configured as described above. Next, the operation will be described. In normal use, the load is supported by balls 15. The cylindrical roller 23 does not substantially support the load. The grease is melted by heat generated by rotation during use, and an oil film is formed between the balls 15 and the tracks 13 and 14. An oil film is also formed on the current-carrying surfaces 17 and 18 of the inner and outer rings. However, the minute projections by the unevenness 19 or the processed minute projections 20 existing on the current-carrying surfaces 17 and 18 break the oil film and Metal contact with outer surface.

  In such a state, when current flows from the inner ring 11 side or the outer ring 12 side, an oil film of grease exists between the balls 15 and the raceways 13 and 14, and thus the electric resistance value is high. It is known that even when the oil film is incomplete and the resistance value decreases, there is a high resistance of about 1 MΩ.

Compared to the resistance between the ball 15 and the raceways 13 and 14, the short circuit path through the cylindrical roller 23 has a structure in which the cylindrical roller 23 is in metal contact with the minute protrusions of the current-carrying surfaces 17 and 18 where the oil film is broken. Much lower resistance. For this reason, the current flows through a short-circuit path passing through the current-carrying surfaces 17 and 18 and the cylindrical roller 23. As a result, no spark is generated between the ball 15 and the tracks 13 and 14, and electrolytic corrosion is prevented.
When the balls 15 are small, needle rollers can be used instead of the cylindrical rollers 23.

  The rolling bearing of the second embodiment shown in FIGS. 8 to 10 has basically the same configuration as that of the first embodiment, but differs only in the configuration of the current-carrying surfaces 17 and 18. That is, in this case, the current-carrying surfaces 17 and 18 are processed, and a plurality of minute protrusions 22 are formed in parallel over the entire circumference. The height of the minute protrusions 22 is about the same as or slightly higher than the oil film 21 (see the one-dot chain line in FIG. 9) due to the grease existing on the current-carrying surfaces 17 and 18. Such minute protrusions 22 are also included in the “minute protrusions” referred to in “claim 2”.

  When the bearing is stopped, grease accumulates in a groove formed between the minute protrusions 22. When the grease is melted and the oil film 21 is formed by the heat generated during the rotation, the tip of the fine protrusion 22 protrudes to be equal to or higher than the oil film 21, and the oil film 21 is broken and exposed. The width of the tip of the fine protrusion 22 is narrowed to such an extent that it is eliminated by the contact pressure when contacting the cylindrical roller 23 and no oil film remains on the tip surface.

The microprojections 22 may be continuous or partially interrupted over the entire circumference, and a large number of independent microprojections having a shape obtained by cutting the microprojections 22 in the axial direction may be disposed on the entire circumference. It may be formed in a crossover shape.
Since other configurations and operations are the same as those in the first embodiment, the description thereof is omitted.

  As described above, as a mode in which minute protrusions are formed on the current-carrying surfaces 17 and 18 and are brought into metal contact with the cylindrical rollers 23, countless numbers included in the rough surfaces left without finishing the current-carrying surfaces 17 and 18 are included. Formed by the projections and depressions 19 (see FIG. 5A), formed by the dispersed minute projections 20 formed over the entire circumference (see FIG. 5B), or continuous over the entire circumference. And the like (see FIG. 10) formed by the required number of minute protrusions 22. The inner and outer current-carrying surfaces 17 and 18 can have the same combination of modes or different combinations.

  The rolling bearing of the third embodiment shown in FIG. 11 has basically the same configuration as that of the first embodiment, but is different only in the configuration of the current-carrying surfaces 17 and 18. That is, in the case of the third embodiment, circumferential grooves 31 and 32 of a required depth are provided on the inner ring outer diameter surface 11a and the outer ring inner diameter surface 12a on both sides of the raceway 13 of the inner ring 11 and the raceway 14 of the outer ring 12, and Current-carrying surfaces 17 and 18 of the inner and outer rings are formed at the groove bottoms of the grooves 31 and 32.

  The diameter of the energizing cylindrical roller 23 is larger than that of the first embodiment by the depth of the circumferential grooves 31 and 32, and both ends thereof are in contact with the energizing surfaces 17 and 18, respectively. Small protrusions (see FIGS. 5A, 5B, and 10) are formed on the current-carrying surfaces 17 and 18.

  With such a configuration, the diameter of the cylindrical roller 23 becomes relatively large, so that the outer diameter of the revolution approaches the outer diameter of the revolution of the ball 15. Thereby, the peripheral speed difference of both revolutions becomes small.

  When the peripheral speed difference between the revolution of the ball 15 and the cylindrical roller 23 is large, vibration may be generated in the cage 16 and the durability of the cage 16 may be reduced. However, when the configuration as in the third embodiment is adopted, the peripheral speed difference is reduced, so that the vibration of the cage 16 is suppressed and the durability can be increased.

  Since other configurations and operations are the same as those in the first embodiment, the description thereof is omitted.

Sectional view of Example 1 Sectional view of the _X 1 -X ₁ line in FIG 1 Sectional view of the _X 2 -X ₂ line in FIG. 1 Sectional view of the _X 3 -X ₃ line in FIG. 1 (A) (b) The elements on larger scale which show the example of the electricity supply surface part in the case of Example 1 The partial perspective view of the holder | retainer part of Example 1. FIG. Sectional view along line X ₄ -X ₄ in FIG. Partially omitted sectional view of Example 2 Partially omitted enlarged sectional view Partial enlarged view showing the energizing surface part in the case of Example 2 Partially omitted sectional view of Example 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Inner ring 11a Inner ring outer diameter surface 12 Outer ring 12a Outer ring inner diameter surface 13 Track 14 Track 15 Ball 16 Cage 17 Carrying surface 17 Current carrying surface 18 Current carrying surface 19 Concavity and convexity 20 Micro projection 21 Oil film 22 Micro projection 23 Cylindrical roller 25 Ball holding portion 26 Roller holding portion 27 Seal member 28 Seal member 29 Bent part 31 Circumferential groove 32 Peripheral groove

Claims (11)

An inner ring (11) and an outer ring (12) constituting the raceway ring, a required number of rolling elements interposed between the inner ring (11) and the outer ring (12), and a cage (16) for holding these rolling elements. In the rolling bearing
At least one energizing rolling element is interposed in the rolling element while being held by the cage (16), and an inner ring energizing surface (17) is provided on the outer diameter surface (11a) of the inner ring (11). An outer ring energizing surface (18) is provided on an inner diameter surface (12a) of the outer ring (12), and the energizing rolling element is in metal contact with the inner ring energizing surface (17) and the outer ring energizing surface (18). Rolling bearing.   2. The rolling bearing according to claim 1, wherein the metal contact is performed by contact between a large number of minute protrusions existing on the entire circumference of each of the current-carrying surfaces (17, 18) and the current-carrying rolling element. .   The minute protrusions on the respective current-carrying surfaces (17, 18) are formed by innumerable irregularities (19) included in the rough surface left without finishing the current-carrying surfaces (17, 18). The rolling bearing according to claim 2.   The minute protrusions on each of the current-carrying surfaces (17, 18) are formed by dispersed minute protrusions (20) formed over the entire circumference of the current-carrying surface (17, 18). Rolling bearings as described in   The rolling bearing according to claim 2, wherein the minute protrusions on each of the current-carrying surfaces (17, 18) are formed by a required number of minute protrusions (22) formed over the entire circumference.   The minute projections on each of the current-carrying surfaces (17, 18) are formed by innumerable irregularities (19) included in the rough surface left without finishing the current-carrying surface, over the entire circumference. 3. The one formed by dispersed fine protrusions (20) formed, or one formed by a required number of fine protrusions (22) continuous over the entire circumference. Rolling bearings as described in   The height of the minute projections formed on each of the energization surfaces (17, 18) is the thickness of the lubricant oil film (21) generated between the energization rolling element and each of the energization surfaces (17, 18). The rolling bearing according to any one of claims 1 to 6, wherein the rolling bearing is formed at the same level or higher.   The energizing rolling element is pressed against the inner ring energizing surface (17) by contact with a bent portion (29) provided in the retainer (16). Rolling bearings as described in   9. A rolling bearing according to claim 1, wherein the rolling elements are formed by balls (15) and the energizing rolling elements are formed by cylindrical rollers (23).   The inner ring energizing surface (17) is provided on both sides of the raceway (13) of the inner ring (11), and the outer ring energizing surface (18) is provided on both sides of the raceway (14) of the outer ring (12). The rolling bearing according to any one of claims 1 to 9.   Circumferential grooves (31, 32) having a required depth are provided on both sides along the tracks (13, 14) of the inner ring (11) and the outer ring (12), and the groove bottoms of the respective circumferential grooves (31, 32) are provided. The rolling bearing according to claim 10, wherein each of the current-carrying surfaces (17, 18) is formed on the surface.

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