JP5348271B2 - Ball bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball bearing capable of reducing stir resistance of a lubricating oil to reduce torque even when the ball diameter or the number of balls is reduced. <P>SOLUTION: This ball bearing includes an inner ring, an outer ring, a plurality of balls arranged rollably between the inner and outer rings, and a plastic retainer provided with a plurality of pockets for holding the balls at predetermined intervals along the circumferential direction thereof. In the ball bearing, the distance L between the balls held in the adjacent pockets is equal to or more than twice as much as the ball diameter Da. A projecting part is formed between adjacent pairs of claw pieces of the plastic retainer, a separation part is formed between the claw piece and the projecting part, and the separation part is connected to the projecting part through a tapered surface. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a ball bearing preferably used for a transmission of an automobile, and more particularly to a ball bearing provided with a plastic crown-shaped cage.

  In general, deep groove ball bearings used under oil lubrication, such as automobile transmissions, are SUJ2 for bearing steel and SCR420 for case-hardened steel as materials for balls, inner rings and outer rings as rolling elements. A steel material or the like equivalent to SCM420 is used. In addition, an iron corrugated press holder made of SPCC or a plastic crown holder is used as a holder for holding the balls so as to roll freely.

  In recent years, due to increasing environmental problems, there is an increasing need for extremely low torque in bearing parts constituting automobile transmissions.

  The causes of friction loss torque of ball bearings are [1] rolling friction between inner and outer rings and balls, [2] sliding friction between inner and outer rings and balls, [3] sliding friction between balls and cages, [4] Although there is a stirring resistance of the lubricating oil, as means for achieving a reduction in torque of the ball bearing, reduction of load conditions and size reduction of the bearing are generally used.

  However, in such a means, there are problems such as a decrease in bearing life and rigidity, or a restriction on a bearing mounting peripheral structure.

  In addition, from the viewpoint of the above [3], in recent years, plastic cages that are lightweight and have excellent self-lubricating properties are increasingly used for transmission ball bearings.

  Further, from the viewpoint of the above [4], it is conceivable to reduce the amount of oil supplied to the bearing or to lower the viscosity of the lubricating oil. However, with these means, there are restrictions on the performance of the bearing and unit, This method is also affected by the operating conditions (for example, the number of revolutions of the engine or other rotating members), so that there is a problem that it is difficult to control in the above method.

  In general, ball bearings used in transmissions have particularly strict bearing life requirements. Unless otherwise specified, balls are placed in the space between the inner ring and the outer ring as much as possible within the given space. In general, a design that maximizes the rated load is made. However, in view of the above, techniques such as optimization of the ball diameter and the number of balls are effective in order to enable torque reduction to the maximum within a given dimension.

  As a conventional cage for ball bearings, there is a crown type structure shown in FIGS. 8 and 9 (see, for example, Patent Document 1). 8 is a perspective view of the cage, and FIG. 9 is a partial development view of the cage of FIG.

  The cage 31 is made of plastic and is formed into a so-called crown shape, and the annular cage body 32 opens on one axial surface in the axial direction so that the balls can roll and cannot be dropped. A plurality of pockets 35 to be held are arranged in the circumferential direction. The pockets 35 are equally spaced.

  The opening end portions of these pockets 35 are formed by a pair of claw pieces 33a and 33b located on both sides of the pocket opening in the circumferential direction of the cage body, and the inner surface of the pocket 35 is spherical. The claw pieces 33a and 33b on both sides of the pocket 35 are shaped so that the tips approach each other, and the entrance diameter between the claw pieces 33a and 33b is smaller than the ball diameter.

  The assembly of the bearing is performed by a snap-on method in which the tips of the claw pieces 33a and 33b are slightly pushed by the balls 36. In other words, the claw pieces 33a and 33b formed on the cage 31 need to be freely deformed to some extent. If the rigidity is too high, the assembling property is lowered, or the cage 31 is damaged during the assembly, Due to the permanent deformation, the opening that is the ball insertion opening becomes large, and the cage 31 may be easily detached during rotation.

  Therefore, the general plastic retainer 31 has a recess 34 between the claw pieces 33a and 33b between the adjacent pockets 35, so that the claw pieces 33a and 33b can be elastically deformed.

Further, as shown in FIG. 9, generally, the distance L between balls 36 in the pocket 34 is:
L = π dm / z (dm: PCD, z: number of balls)
It is set to become.

Japanese Patent Laying-Open No. 2003-329045 (FIG. 2)

  However, these claw pieces 33a and 33b have a complicated shape of projecting in different directions while curving from the cage main body 32, so that there is a problem that the lubricating oil is unnecessarily agitated when the bearing rotates.

  Therefore, if the ball diameter is reduced or the number of balls is reduced in order to reduce torque, the influence of the stirring resistance of the lubricating oil by the claw pieces 33a and 33b provided on the front side (pocket side) of the cage 31 is ignored. Can not. In particular, when the bearing has a large PCD (pitch circle diameter), the influence of the lubricating oil stirring resistance by the claw pieces 33a and 33b is large.

  An object of the present invention is to solve the above problem, and to provide a ball bearing capable of reducing the stirring resistance of the lubricating oil and reducing the torque even when the ball diameter is reduced or the number of balls is reduced. It is in.

  The above object of the present invention is achieved by the following configurations.

(1) inner ring,
Outer ring,
A plurality of balls arranged to roll between the inner ring and the outer ring;
In a ball bearing comprising a plastic cage provided with a plurality of pockets for holding the balls at predetermined intervals along the circumferential direction,
In the plastic cage, a plurality of pairs of claw pieces constituting the opening end of each pocket are formed in the circumferential direction,
A convex portion is formed between the pair of adjacent nail pieces,
A spacing portion is provided between the claw piece and the convex portion,
The spacing portion and the convex portion are connected by a tapered surface,
When the distance L between the balls held in the adjacent pockets is 2 to 5 times the ball diameter Da, and the ball PCD is dm and the number of balls is Z, L = π · dm / z is satisfied. And
The height H of the convex portion satisfies H ≦ Da / 2,
Width of the bottom surface of the spacing portion, when the width of the open end to is W, ball bearings, characterized in Succoth satisfy (Da-W) / 2 or more.

(2) The connecting portion between the convex portion and the tapered surface is provided with a roundness ,
The corner of the bottom surface of the spacing portion is rounded,
The taper angle of the taper surface is 1 to 5 °, and the ball bearing according to (1).
( 3 ) The convex portion is formed in an arc shape when viewed from the axial direction,
The ball bearing according to (1) or (2) , characterized in that a radial width of the convex portion and the claw piece is set to the same width.

  According to the ball bearing of the present invention, when the number of balls is reduced, the agitation resistance of the lubricating oil by the claw pieces of the cage can be greatly reduced, so that the torque of the bearing can be reduced.

The configuration of the present invention is particularly effective when the bearing PCD is large and the number of balls is small.
The ball bearing of the present invention is effective for low friction and high speed rotation in, for example, an automobile transmission, and is preferably used for a hybrid vehicle.

It is a perspective view of the holder | retainer which is 1st Embodiment of this invention. It is principal part sectional drawing of the ball bearing which is 1st Embodiment of this invention. It is a partial expanded view of the holder | retainer of 1st Embodiment of this invention. It is a principal part enlarged view of FIG. It is a perspective view of the holder | retainer which is 2nd Embodiment of this invention. It is a partial expanded view of the holder | retainer of 2nd Embodiment of this invention. It is a principal part enlarged view of FIG. It is a perspective view of the conventional holder | retainer. FIG. 10 is a partial development view of the cage of FIG. 9.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view of a plastic cage for ball bearings according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of an essential part of the ball bearing according to the first embodiment of the present invention, and FIG. FIG. 4 is a partially expanded view of the cage of the first embodiment, and FIG.

  As shown in FIG. 2, the ball bearing 1 is obtained by incorporating a plastic cage 2 holding a ball 14 between an inner ring 3 and an outer ring 4.

  The cage 2 has a configuration in which a pocket 12 and a convex portion 13 described later are integrally formed at a predetermined interval in an annular cage body 11 shown in FIG. 1 and a ball 14 is fitted into each pocket 12 by a snap-on method. ing. The pockets 12 are provided in the retainer body 11 at a predetermined amount of regular intervals. The number of pockets 12 can be freely changed as necessary.

  In the present embodiment, a total of five pockets 12 are illustrated, but since the configuration of each pocket 12 is the same, a description will be given with a common reference. The opening end of the pocket 12 is formed by a pair of elastic claw pieces 16a and 16b, and the opposing side surfaces of the claw pieces 16a and 16b are curved so as to hold the ball 14 in a freely rollable manner.

  The upper ends of the pair of claw pieces 16a and 16b are set to have a small width W with respect to the diameter Da of the ball as shown in an enlarged manner in FIG. Therefore, as shown by an imaginary line in FIG. 4, when a ball is pushed in from the opening of the pocket 12, the pair of claw pieces 16a and 16b are slightly opened as indicated by the imaginary line. Further, by pushing the ball 14 further, the ball 14 enters the pocket 12 against the elastic force of the pair of claw pieces 16a and 16b, and is stored and held so as to be able to roll.

  In other words, the ball 14 is stored in the pocket 12 by the snap-on method and is held so as to be able to roll. However, in the stored state, the pair of claw pieces 16a and 16b have an original shape as shown by a solid line in FIG. The ball 14 is held again. Therefore, the ball 14 does not come out of the pocket and can roll stably.

  On the outer side along the circumferential direction of the pair of claw pieces 16a and 16b, a convex portion 13 is formed via spacing portions 18a and 18b. And the side surface of the both ends of the circumferential direction of the convex part 13 is formed in the taper surface of about 1-5 degrees, and the top part of the convex part 13 is formed flat.

  The height H of the convex portion 13 from the bottom surface of the spacing portions 18a and 18b is the same as the height of the claw pieces 16a and 16b, and the height H is set to be equal to or less than the radius (Da / 2) of the ball. That is, when the diameter of the ball is Da, a relationship of H ≦ Da / 2 is set. This height H is freely set by changing the depth of the separating portions 18a and 18b. Further, the corners of the bottom surfaces of the separating portions 18a and 18b and the corner portions of the convex portion 13 are set to be rounded to about 0.2R.

  The convex portion 13 is formed in an arc shape between the pockets 12 provided in the cage body 11 as viewed from the axial direction. When the interval between the centers of the pockets 12 is L and the diameter of the ball 14 is Da, as shown in FIG. 3, L = 2 Da to 5 Da is set. And the convex part 13 stands | starts up from each pocket 12 via the spacing parts 18a and 18b, and the axial direction edge part is formed flat.

  Further, the height H of the convex portion 13 is the same as the height of the claw pieces 16a and 16b, and the width in the radial direction is also formed to the same width as the claw pieces 16a and 16b.

  Therefore, when the cage 2 is assembled in the state shown in FIG. 2 and rotated at a high speed, the flat surface of the convex portion 13 continues in the circumferential direction at the same height as the tips of the claw pieces 16a and 16b. No special stirring resistance is generated only at 16a and 16b, the flow of the lubricating oil can be adjusted, and the loss torque can be greatly reduced.

  Further, when the torque is reduced by reducing the number of balls and the number of pockets, the interval between the pockets 12 becomes longer, but the conventional concave portions are not continuous between the pockets 12, and the convex portions 13 are continuous. Therefore, the lubricating oil is not agitated in the vicinity of the claw pieces 16a and 16b, and the loss torque can be greatly reduced.

  In order to store the ball 14 in the pocket 12 by the snap-on method, the pair of claw pieces 16a and 16b must be elastically opened. On the other hand, the cage body 11 is made of plastic, and the claw pieces 16a and 16b as well as the separating portions 18a and 18b and the convex portion 13 are integrally formed. Therefore, it is necessary to prevent the claw pieces 16a and 16b from falling inward in the radial direction of the cage 2 due to shrinkage during cooling following the molding process.

  If the claw pieces 16a and 16b are inclined inward in the radial direction of the cage 2, not only the dimensional accuracy can be obtained and the ball 14 cannot be snapped on, but the rigidity of the cage 2 is insufficient during high-speed rotation. Thus, the cage 2 may be damaged due to deformation of the outward opening due to centrifugal force.

  Therefore, in the present embodiment, in order to prevent such a problem and to prevent the elastic deformation of the claw pieces 16a and 16b at the time of assembly, the minimum width at the bottom of the separating portions 18a and 18b is set to the claw piece 16a. , 16b is set to be equal to or greater than the amount of elastic deformation ((Da-W) / 2). According to such a configuration, it is possible to prevent occurrence of problems during assembly.

  Next, a second embodiment of the present invention will be described. FIG. 5 is a perspective view of a cage according to the second embodiment, FIG. 6 is a partial development view of the cage according to the second embodiment, and FIG. 7 is an enlarged view of a main part of FIG.

  The second embodiment differs from the first embodiment in the configuration of the separating portions 20a and 20b. As described above, the minimum width at the bottom of the separation portions 20a and 20b is set to be equal to or greater than the elastic deformation amount of the claw pieces 16a and 16b. In the second embodiment, the width of the separation portions 20a and 20b is the first embodiment. It is narrower than. Since other configurations are the same as those of the first embodiment, the same configurations as those of the first embodiment are denoted by the same reference numerals in FIGS. This is the same as the embodiment.

  In this manner, the claw pieces 16a, 16b and the convex portion 13 are close to each other because the width of the separation portions 20a, 20b is narrow, so that the claw pieces 16a, 16b and the convex portion 13 integrally rectify the lubricating oil, The stirring action of the lubricating oil by the claw pieces 16a and 16b does not occur.

  The width of the spacing portions 20a and 20b is preferably as narrow as possible so as not to hinder the elastic deformation of the claw pieces 16a and 16b, and the rectifying action of the lubricating oil by the convex portion 13 is second than that of the first embodiment. The embodiment is superior.

DESCRIPTION OF SYMBOLS 1 Bearing 2,22,31 Cage 3 Inner ring 4 Outer ring 11, 32 Cage body 12, 35 Pocket 13 Convex part 14 Balls 16a, 16b, 33a, 33b Claw pieces 18a, 18b, 20a, 20b Separation part

Claims (3)

Inner ring,
Outer ring,
A plurality of balls arranged to roll between the inner ring and the outer ring;
In a ball bearing comprising a plastic cage provided with a plurality of pockets for holding the balls at predetermined intervals along the circumferential direction,
In the plastic cage, a plurality of pairs of claw pieces constituting the opening end of each pocket are formed in the circumferential direction,
A convex portion is formed between the pair of adjacent nail pieces,
A spacing portion is provided between the claw piece and the convex portion,
The spacing portion and the convex portion are connected by a tapered surface,
When the distance L between the balls held in the adjacent pockets is 2 to 5 times the ball diameter Da, and the ball PCD is dm and the number of balls is Z, L = π · dm / z is satisfied. And
The height H of the convex portion satisfies H ≦ Da / 2,
Width of the bottom surface of the spacing portion, when the width of the open end to is W, ball bearings, characterized in Succoth satisfy (Da-W) / 2 or more. The connecting portion between the convex portion and the tapered surface is provided with a roundness ,
The corner of the bottom surface of the spacing portion is rounded,
The ball bearing according to claim 1, wherein a taper angle of the tapered surface is 1 to 5 ° . The convex portion is formed in an arc shape when viewed from the axial direction,
The ball bearing according to claim 1 or 2 , wherein the radial width of the convex portion and the claw piece is set to the same width.

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