JP2008304033A - Ball bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball bearing suitably and inexpensively usable even in high-temperature and high-speed conditions while keeping a cage less liable to deformation. <P>SOLUTION: The resin crowned cage 4 incorporated in the ball bearing has a plurality of pockets 11 in one axial end face of an annular main portion 10 for rollingly holding balls 3. The pockets 11 each consist of a recessed portion 11a provided in one axial end face of the main portion 10, and a pair of elastic pieces 11b, 11b arranged opposing each other at the edge of the recessed portion 11a in mutually spaced relation. The opposed faces of the pair of elastic pieces 11b, 11b and the inner face of the recessed portion 11a continuously form one spherical recessed face. An axial distance A between the axial position of a gravity center G of the cage 4 and a curvature center O of the spherical inner face of the pocket 11 is 0.6-0.9 time a curvature radius r of the spherical inner face of the pocket 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball bearing.

In order to support various rotating parts, for example, ball bearings as shown in FIG. 5 are widely used. In this ball bearing, an inner ring 102 having an inner ring raceway 101 on an outer peripheral surface and an outer ring 104 having an outer ring raceway 103 on an inner peripheral surface are arranged concentrically, and a plurality of balls are arranged between the inner ring raceway 101 and the outer ring raceway 103. 105 has a structure in which it can freely roll.
The plurality of balls 105 are held by a cage 107 as shown in FIGS. The cage 107 is called a crown-shaped cage and is integrally formed by injection molding a synthetic resin. The cage 107 includes an annular main portion 108 and a plurality of pockets 109 provided on one end surface in the axial direction of the main portion 108, and each pocket 109 is aligned with the axial direction of the main portion 108. The recess 110 is formed on the end surface, and a pair of elastic pieces 111 and 111 are arranged on the edge of the recess 110 so as to face each other with a space therebetween. And the mutually opposing surface of this pair of elastic pieces 111, 111 and the inner surface of the concave portion 110 continuously form one spherical concave surface or cylindrical surface.

Such a cage 107 rolls the ball 105 into each pocket 109 by pushing the ball 105 between the pair of elastic pieces 111 and 111 while elastically expanding the distance between the elastic pieces 111 and 111. It can be held freely.
Conventionally, as a material constituting such a crown-shaped cage, nylon 46, nylon 66, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK) and the like are synthesized. Resins are commonly used. In addition, it is known that toughness and mechanical strength at high temperatures can be increased by including about 10 to 40% by mass of a reinforcing material such as glass fiber (GF) or carbon fiber (CF) in these synthetic resins. It has been.

Such ball bearings are often used under severe conditions such as high temperature and high speed. For example, in the case of a ball bearing incorporated in a rotation support portion of a drive motor or an alternator for a hybrid vehicle, the ball bearing is often used at a high temperature (100 ° C. or higher) and a high speed (rotational speed of 10,000 min ⁻¹ or higher or dmn 600,000 or higher). In addition, dm of dmn is a bearing pitch circle diameter (unit is mm), and n is a rotational speed of the bearing (unit is min ⁻¹ ). Under such usage conditions, the cage 107 in the ball bearing rotates at a high speed together with the lubricating oil and grease existing between the outer peripheral surface of the inner ring 102 and the inner peripheral surface of the outer ring 104. The cage 107 during high-speed rotation is combined with a radially outward force based on centrifugal force, a restraining force based on the revolution of the ball 105 (rotational force), agitation resistance of lubricating oil and grease, and the like. Complex power is added.

  Due to such a complicated force, the cage 107 repeats irregular movements and receives a complicated external stress accompanied by an impact. Therefore, if the operation is continued for a long time under the high temperature and high speed use conditions as described above, elastic deformation or plastic deformation is caused by the action of centrifugal force. As a result, the gap between the inner surface of each pocket 109 and the rolling surface of each ball 105 is increased. Furthermore, the inner surface of each pocket 109 wears due to the force received from the rolling surface of the ball 105. And when this gap becomes large, the following problems occur.

First of all, the cage 107 is vibrated finely with the rotation of the ball bearing, which not only further accelerates the wear of each pocket 109 but also generates harmful vibrations and noises. Second, as a result of releasing the restraint of the cage 107 by the balls 105, the cage 107 is partially or entirely displaced, and a part of the cage 107 rubs against the mating surface. For example, the elastic piece 111 constituting the pocket 109 is displaced radially outward based on, for example, centrifugal force (see FIG. 8), and the outer peripheral surface of each elastic piece 111 and the inner peripheral surface of the outer ring 104 rub against each other.
In order to solve such a problem, a resin cage including a metal reinforcing member has been proposed (for example, Patent Documents 1 and 2). Since the rigidity of the cage is enhanced by the metal reinforcing member, the above-described deformation is less likely to occur even when used under high temperature and high speed conditions.
JP-A-8-145041 Japanese Patent Laid-Open No. 9-79265

However, since the ball bearings described in Patent Documents 1 and 2 are provided with a metal reinforcing member in the resin cage, there is a problem that the manufacturing cost of the ball bearing increases.
Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide an inexpensive ball bearing that can be suitably used even under high temperature and high speed conditions, in which the cage is hardly deformed.

  In order to solve the above problems, the present invention has the following configuration. That is, the ball bearing of claim 1 according to the present invention includes an inner ring, an outer ring, a plurality of rolling elements arranged to roll between the inner ring and the outer ring, and the inner ring and the outer ring between the inner ring and the outer ring. In a ball bearing comprising a resin cage that holds a rolling element, the cage is a crown-shaped cage in which a plurality of pockets that hold the rolling element are formed on one end surface in the axial direction of the annular main portion. And the axial distance between the axial position of the center of gravity of the cage and the center of curvature of the spherical inner surface of the pocket is not less than 0.6 times and not more than 0.9 times the radius of curvature of the spherical inner surface of the pocket. It is characterized by that.

  According to a second aspect of the present invention, the ball bearing includes an inner ring, an outer ring, a plurality of rolling elements that are freely rollable between the inner ring and the outer ring, and the inner ring and the outer ring. In a ball bearing comprising a resin cage that holds a rolling element, the cage is a crown-shaped cage in which a plurality of pockets that hold the rolling element are formed on one end surface in the axial direction of the annular main portion. And the axial distance between the axial position of the center of gravity of the cage and the center of curvature of the spherical inner surface of the pocket is not less than 0.65 times and not more than 0.85 times the radius of curvature of the spherical inner surface of the pocket. It is characterized by that.

Furthermore, the ball bearing according to claim 3 of the present invention is characterized in that, in the ball bearing according to claim 1 or claim 2, the ball bearing is used under conditions of a bearing temperature of 100 ° C. or higher and a rotational speed of 10,000 min ⁻¹ or higher. To do.
Furthermore, a ball bearing according to a fourth aspect of the present invention is characterized in that, in the ball bearing according to the first or second aspect, the ball bearing is used under conditions of a bearing temperature of 100 ° C. or higher and a dmn of 600,000 or higher.

  The ball bearing of the present invention is suitable for use under high speed and high temperature conditions and is inexpensive because the cage is not easily deformed.

DESCRIPTION OF EMBODIMENTS Embodiments of a ball bearing according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a ball bearing according to the present invention. 2 is a perspective view of a cage used in the ball bearing of FIG. 1, and FIG. 3 is a partial sectional view of the cage of FIG.
The ball bearing shown in FIG. 1 includes an inner ring 1, an outer ring 2, a plurality of balls 3 (rolling elements) that are arranged to freely roll between the inner ring 1 and the outer ring 2, and a plurality of balls between the inner ring 1 and the outer ring 2. A resin cage 4 for holding the balls 3 and a shield are provided.
A bearing space in which the balls 3 are arranged between the inner ring 1 and the outer ring 2 is filled with a lubricant (for example, lubricating oil or grease) (not shown). And the contact surface of the raceway surface of the inner ring | wheel 1 and the outer ring | wheel 2 and the ball | bowl 3 is lubricated with this lubricant. Note that a seal may be used instead of the shield, or a sealing device such as a seal or a shield may not be provided.

  Next, the structure of the cage 4 will be described with reference to FIGS. This cage 4 is a crown-shaped cage integrally formed by injection molding of a resin material, and a ball 3 as a rolling element can roll on one end surface in the axial direction of an annular main portion 10. A plurality of pockets 11 to be held are provided. Each pocket 11 is formed of a concave portion 11a provided on one end surface in the axial direction of the main portion 10 and a pair of elastic pieces 11b and 11b arranged to face each other at an edge of the concave portion 11a. . The opposing surfaces of the pair of elastic pieces 11b and 11b and the inner surface of the recess 11a continuously form one spherical concave surface.

  The type of resin material constituting the cage 4 is not particularly limited as long as it has properties such as strength and heat resistance necessary for the cage, but nylon 46, nylon 66, polyphenylene sulfide (PPS). ), Synthetic resins such as polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK). A resin composition containing about 10 to 40% by mass of a reinforcing material such as glass fiber (GF) or carbon fiber (CF) in the resin is particularly preferable because of high toughness and mechanical strength at high temperatures. .

The axial distance A between the axial position of the center of gravity G of the cage 4 and the center of curvature O of the spherical inner surface of the pocket 11 is not less than 0.6 times the radius of curvature r of the spherical inner surface of the pocket 11. It is said that it is less than double. With such a configuration, even when the ball bearing is used at a high temperature (100 ° C. or higher) and at a high speed (rotational speed of 10,000 min ⁻¹ or higher or dmn 600,000 or higher), the cage 4 is hardly deformed. Therefore, this ball bearing can be suitably used under high temperature and high speed conditions. For example, it is suitable as a bearing for supporting the drive shaft of a hybrid vehicle or the rotating shaft of an alternator. Further, since the cage 4 does not include a metal reinforcing member, the ball bearing can be manufactured at low cost.

  This will be described in more detail with reference to FIG. When the ball bearing is used under high temperature and high speed conditions and a large centrifugal force acts on the cage 4, the elastic piece 11b of the pocket 11 is deformed radially outward. This is because since the elastic piece 11b has a cantilever structure, the centrifugal force acts as a moment on the axial position of the center of gravity G of the cage 4 with the rigid center S of the cage 4 as a fulcrum. Note that the rigidity center S is at a substantially intermediate position between the other axial end surface of the main portion 10 (the end surface of the both axial end surfaces of the main portion 10 where the pocket 11 is not formed) and the bottom portion of the pocket 11.

  Therefore, if the axial position of the center of gravity G of the cage 4 is positioned in the vicinity of the rigid center S, the moment is reduced even when a large centrifugal force acts on the cage 4. It can suppress that 11b deform | transforms to radial direction outward, and the main part 10 torsionally deforms (that is, it can suppress that a big deformation | transformation as shown in FIG. 8 arises in a holder | retainer).

  The axial distance A between the axial position of the center of gravity G of the cage 4 and the curvature center O of the spherical inner surface of the pocket 11 is 0.6 times or more and 0.9 times or less of the curvature radius r of the spherical inner surface of the pocket 11. Then, since the axial position of the center of gravity G of the cage 4 and the rigid center S are close to each other, even if centrifugal force acts on the cage 4, deformation of the elastic piece 11 b in the radially outward direction is suppressed. Is done. As the length between the other axial end surface of the main portion 10 and the bottom of the pocket 11, that is, the thickness B of the main portion 10 is increased, the axial position of the center of gravity G of the retainer 4 is Moving in the direction of the other axial end surface, the axial distance A increases. That is, the axial position of the center of gravity G of the cage 4 approaches the rigidity center S.

  If the axial distance A is less than 0.6 times the radius of curvature r, the moment acting on the axial position of the center of gravity G of the cage 4 increases, and the cage 4 may be deformed. On the other hand, if the axial distance A is more than 0.9 times the radius of curvature r, the width of the cage 4 (length in the axial direction) increases, and the cage 4 has a seal device when the ball bearing has a seal device. And the sealing device may come into contact with each other. Further, even when the ball bearing does not have a sealing device, the cage 4 may protrude from the side surface of the ball bearing to the outside, which is a problem. In order to make such inconvenience less likely to occur, the axial distance A is preferably 0.65 times or more and 0.85 times or less the curvature radius r.

The magnitude of the moment based on the centrifugal force acting on the cage when the ball bearing was rotated was determined by calculation. The results are shown in FIG. The vertical axis of this graph is the magnitude of the moment acting on the cage, and the horizontal axis is the pocket distance of the axial distance between the axial position of the center of gravity of the cage and the center of curvature of the spherical inner surface of the pocket. It is a ratio with respect to the radius of curvature of the spherical inner surface (in the graph, it is indicated as the axial position of the center of gravity of the cage). From this graph, it can be seen that the axial distance is preferably at least 0.6 times the radius of curvature of the spherical inner surface of the pocket, more preferably at least 0.65 times.
In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, a deep groove ball bearing has been described as an example of the ball bearing. However, the ball bearing of the present invention can be applied to various types of ball bearings. For example, angular contact ball bearings and self-aligning ball bearings.

It is a longitudinal cross-sectional view which shows one Embodiment of the ball bearing which concerns on this invention. It is a perspective view of the holder | retainer integrated in the ball bearing of FIG. FIG. 3 is a partial cross-sectional view of the cage in FIG. 2. It is a graph which shows the relationship between the axial direction position of the gravity center of a holder | retainer, and the moment which acts on a holder | retainer. It is a longitudinal cross-sectional view which shows the structure of the conventional ball bearing. It is a perspective view of the holder | retainer integrated in the ball bearing of FIG. FIG. 6 is a partial plan view of a cage incorporated in the ball bearing of FIG. 5. It is a side view of the holder | retainer which the elastic piece deform | transformed to radial direction outward.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Ball 4 Cage 10 Main part 11 Pocket 11a Recess 11b Elastic piece A Axial distance between the axial position of the center of gravity of the cage and the center of curvature of the spherical inner surface of the pocket G The center of gravity O of the cage The center of curvature of the spherical inner surface of the pocket S The center of rigidity r The radius of curvature of the spherical inner surface of the pocket

Claims (4)

An inner ring, an outer ring, a plurality of rolling elements that are freely rollable between the inner ring and the outer ring, and a resin cage that holds the rolling elements between the inner ring and the outer ring. In ball bearings,
The cage is a crown-shaped cage in which a plurality of pockets for holding the rolling elements are formed on one end surface in the axial direction of the annular main portion,
The axial distance between the axial position of the center of gravity of the cage and the center of curvature of the spherical inner surface of the pocket is 0.6 to 0.9 times the radius of curvature of the spherical inner surface of the pocket. A characteristic ball bearing. An inner ring, an outer ring, a plurality of rolling elements that are freely rollable between the inner ring and the outer ring, and a resin cage that holds the rolling elements between the inner ring and the outer ring. In ball bearings,
The cage is a crown-shaped cage in which a plurality of pockets for holding the rolling elements are formed on one end surface in the axial direction of the annular main portion,
The axial distance between the axial position of the center of gravity of the cage and the center of curvature of the spherical inner surface of the pocket is 0.65 to 0.85 times the radius of curvature of the spherical inner surface of the pocket. A characteristic ball bearing. The ball bearing according to claim 1 or 2, wherein the ball bearing is used under conditions of a bearing temperature of 100 ° C or more and a rotational speed of 10,000 min ^-1 or more.   The ball bearing according to claim 1 or 2, wherein the ball bearing is used under conditions of a bearing temperature of 100 ° C or higher and a dmn of 600,000 or higher.

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