Roller bearing retainer

Abstract: In a roller bearing retainer generation of vibration may be suppressed and sufficient lubrication performance may be ensured. A flat portion 5 is formed at a bottom portion of each ball pocket 4 having an opening portion formed on one side surface in an axial direction of a flat-shaped member in a circumferential direction. A rolling member is held by the ball pocket 4 which has the flat portion 5. A movement of the rolling member is suppressed. At the same time, a sufficient gap may be formed between the rolling member and a concave surface other than the flat portion 5 may be formed. Thus, lubrication oil may readily be spread into the gap.

Description: BACKGROUND OF THE INVENTION 1. Field of Invention The present invention relates to a retainer for rolling bearing for holding a rolling member such as a ball, in which a flat portion is formed in a ball pocket having a spherical inner circumferential surface. 2. Description of the Related Art A conventional retainer for rolling bearing (hereinafter simply referred to as a retainer) will now be described with reference to Fig. 5 which shows an example of a retainer 1 used in a bearing to which a load is applied in a radial direction, i.e., a radial rolling bearing. The retainer 1 is formed of a ring-shaped member. A plurality (eight in the drawing) of ball pockets 2 for holding rolling members (not shown) such as balls are formed on one side surface in the axial direction. Inner circumferential surfaces (concave surfaces) of these ball pockets 2 are formed into spherical shape corresponding to the shape of the outer circumferential surfaces of the rolling members. The rolling members are mounted on the retainer 1 to thereby form a bearing body for the rolling bearing. In the above-described prior art, in case of the retainer for holding the rolling members only with the single concave surface (spherical surface) formed in each ball pocket, in order to reduce vibration of the retainer, it is effective to reduce a curvature of the concave surface of the ball pocket and to narrowly hold the rolling member, i.e., to use a method to hold the rolling member so as not to generate any gap between the rolling member and the concave surface. However, in this case, lubricant is not introduced in between the rolling member and the concave surface. In some cases, the lubrication for the rolling member would be sacrificed. Thus, there is a fear that a service life of a normal noise preventing function would be shortened. Also, inversely, it is available to increase a curvature of the concave surface of the ball pocket in view of the sufficient lubrication to the rolling members. However, in such a case, an amount of movement of the retainer relative to the rolling member is increased and vibration would be generated in the retainer when the bearing is rotated so that there is a fear that the service life of the noise preventing function that should be maintained normally would be degraded. SUMMARY OF THE INVENTION In order to overcome the above-noted defects, an object of the present invention is to provide a rolling bearing retainer which has a sufficient lubrication function and in which vibration of the retainer is suppressed. According to the invention, there is provided a rolling bearing retainer in which a plurality of ball pockets having opening portions on one side surface in an axial direction of a ring-shaped member which are formed at equal intervals in a circumferential direction, and a plurality of rolling members wich can be held by the ball pockets, whereby at least one flat portion, which is to be brought into contact with the rolling member held in the ball pocket, is formed in the inner circumferential surface of each of the ball pockets, the remainder of the inner circumferential surfaces of the pockets is spherically shaped corresponding to the outer circumferential surfaces of the rolling members, and the width of the flat portion in the radial direction is smaller than the radial width of the rolling bearing retainer at that position. According to the invention, at least one flat portion with which the rolling member is brought into contact is formed in the inner circumferential surface of each ball pocket formed at the equal interval in the circumferential direction on one side surface in the axial direction of the ring-shaped member, whereby the movement of the rolling member which is engaged with the ball pocket at the flat portion is suppressed. Also, the gap between the concave surface (spherical surface) other than the flat portion and the rolling member is formed largely to thereby enhance the flow of the lubricant to enhance the lubrication of the rolling member. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a perspective view showing a rolling bearing retainer according to one embodiment of the present invention; Fig. 2 is a cross-sectional view taken along the line A-A of Fig. 1; Fig. 3 is an enlarged view of a part of a ball pocket shown in Fig. 2; Fig. 4 is a top plan view of that shown in Fig. 1; and Fig. 5 is a perspective view showing a conventional rolling bearing retainer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to Figs. 1 to 4. In Fig. 1, reference numeral 3 denotes a rolling bearing retainer according to the present invention. The retainer 3 is formed of a substantially ring-shaped member. A plurality of ball pockets 4 are formed to hold rolling members. On one side surface facing axial direction of the ring-shaped member, a plurality of ball pockets 4 inner surface (concave surface) of which are formed correspondingly to the shape of outer periphery surface of rolling member, with which rolling member is held, are provided. The ball pockets 4 are formed at an equal interval in the circumferential direction, i.e., at eight positions at an angular interval of 45 ° as shown in Fig. 4. The retainer 3 is made of resin, for example, thermoplastic resin such as nylon 66, PPS (polyphenylene sulfide) or the like. A flat portion 5 is formed on a circumferential surface of the ball pocket 4 of the retain 3, i.e., a bottom of each ball pocket 4. The flat portion 5 is formed only at one position of the bottom surface of the ball pocket 4. However, it is possible to provide the flat portion 5 at a position other than the bottom surface of the concave surface (spherical surface). When the retainer 3 supports the rolling member, in the prior art, the rolling member is supported on the concave surface (spherical surface), whereas according to the present invention, the rolling member is supported on a line or at a point by the above-described flat portion 5. By providing such flat portion 5, the movement of the rolling member within the ball pocket 4 may be suppressed by the flat portion 5. Namely, the amount of the movement of the retainer 3 relative to the rolling member is suppressed. The amount of movement of the above-described retainer 3 relative to the rolling member, which is one of factors causing vibration of the retainer 3, may be controlled in design by setting a dimension (parameter) of a portion other than the flat portion and/or a line or a point of the flat surface 5 in which the ball pocket 4 of the retainer 3 is in contact with the rolling member. Also, with respect to the concave surface (spherical surface) constituting the portion other than the flat portion of the ball pocket 4, in order to accelerate the supply of the lubricant into the ball pocket 4, the curvature of the concave surface (spherical surface) of the ball pocket 4 is set to be large in order to provide a sufficient gap between the concave surface (spherical surface) of the ball pocket 4 and the surface of the rolling member. Thus, the amount of the movement of the retainer 3 relative to the rolling member may be suppressed, and the lubrication performance of the retainer may be ensured. As described above, since the flat portion 5 is formed at one position within the ball pocket 4 of the retainer 3, if the rolling member is narrowly held by the flat portion 5, i.e., in such a manner that any gap is not generated between the rolling member and the concave surface, the amount of movement of the retainer 3 relative to the rolling member becomes small to thereby suppress the vibration. Also, since a sufficient gap is formed between the concave surface and the rolling member at a portion of the concave surface (spherical surface) other than the flat portion 5, the lubricant is effectively spread into the gap to thereby enhance the lubrication performance. Incidentally, if one or more flat portions 5 are formed, the movement of the rolling member is suppressed and the lubrication property is not degraded. However, the number of the flat portions 5 is excessive, the smoothness of the mutual movement between the rolling member and the retainer 3 would be degraded. According to the invention, since an interior of the ball pocket is defined by the concave surface (spherical surface) and one or more flat portions, even if the curvature of the concave surface is not small, it is possible to hold the rolling member in the suppressed condition by the flat portions. Thus, the amount of movement of the retainer relative to the rolling member is suppressed so that the vibration of the retainer may be reduced. Accordingly, upon the rotation of the bearing, the generation of the vibration is reduced and it is possible to enhance the noise preventing function and the rotational performance. Also, with the flat surface provided inside of the ball pocket, since the movement of the retainer to the rolling member is suppressed, the curvature of the concave surface may be set large so that the lubricant may be effectively spread in between the concave surface and the rolling member. As a result, it is possible to enhance the lubrication property and to prolong the service life of the noise preventing function. As described above, it is also possible to prolong the service life of the rolling bearing. Furthermore, by setting the dimension of the position where the retainer is brought into contact with the rolling member, i.e., the line and point of the flat portion or the surface of the portion other than the flat portion, i.e., by setting the parameter of holding the rolling member, it is possible to control the amount of movement of the retainer relative to the rolling member and to suppress the vibration of the rolling bearing retainer with good lubrication property. Thus, it is possible to simultaneously attain the improvement of the noise preventing function and the rotation property. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the embodiments according to the present invention is provided for the purpose of illustration only, and not for the purpose of limiting the invention as defined by the appended claims.

Claims: A rolling bearing retainer (3), comprising: a plurality of ball pockets (4) having opening portions on one side surface in an axial direction of a ring-shaped member which are formed at equal intervals in a circumferential direction; a plurality of rolling members which can be held by said ball pockets (4); whereby at least one flat portion (5), which is to be brought into contact with the rolling member held in the ball pocket (4), is formed in the inner circumferential surface of each of said ball pockets (4); the remainder of the inner circumferential surfaces of said ball pockets (4) is spherically shaped corresponding to the outer circumferential surfaces of the rolling members; and the width of said flat portion (5) in the radial direction is smaller than the radial width of the rolling bearing retainer (3) at that position. A rolling bearing retainer according to claim 1, wherein a lubricating gap is maintained between the rolling member and the inner circumferential surfaces of the ball pocket (4) it resides in as a result of the seating of the rolling member upon the at least one flat portion (5). A rolling bearing retainer according to claim 1, wherein said at least one flat portion (5) is formed on the bottom surface of each of the ball pockets (4).

Inventors: MATSUOKA HIDEKI, MATSUOKA, HIDEKI, Matsuoka, Hideki, c/o Minebea Co., Ltd.
Applicants: MINEBEA KK, MINEBEA CO., LTD.
Application year: 1999
Main classification: F16C33
IPC codes: F16C33