Ball bearing

Abstract

A ball bearing includes an inner ring having a raceway surface, an outer ring having a raceway surface, a plurality of rolling elements rollably disposed between the raceway surface of the inner ring and the raceway surfaces of the outer ring, and a resin cage configured to retain the plurality of rolling elements between the inner ring and the outer ring. The cage is a crown type cage having an annular base portion and a plurality of pockets formed in an axial end face of the annular base portion, in which the pockets retain the rolling elements. An axial distance between an axial position of a center of gravity of the cage and a curvature center of a spherical or cylindrical inner surface of each of the pockets is 0.6 or more times a radius of curvature of the inner surface. A hybrid vehicle transmission has this ball bearing.

The invention claimed is: 
     
       1. A ball bearing comprising:
 an inner ring comprising an outer circumferential surface wherein the outer circumferential surface has a tapered portion extending from an axial end of the inner ring to a first shoulder portion of the inner ring and defining a boundary of an annular supply opening, a second shoulder portion of the inner ring defining a portion of an annular discharge opening, and a raceway groove provided between the first shoulder portion of the inner ring and the second shoulder portion of the inner ring, the raceway groove defining a raceway surface on an in the outer circumferential surfacethereof; 
 an outer ring comprising an inner circumferential surface wherein the inner circumferential surface has a first shoulder portion of the outer ring having an engagement groove nearer to an axial end of the outer ring than to an opposite axial end of the outer ring, a second shoulder portion of the outer ring defining another portion of the annular discharge opening, and a raceway groove provided between the first shoulder portion of the outer ring and the second shoulder portion of the outer ring, the raceway groove of the outer ring defining a raceway surface on an in the inner circumferential surfacethereof; and 
 a plurality of balls rollably disposed between the raceway surface of the raceway groove of the inner ring and the raceway surface of the raceway groove of the outer ring; 
 a cage configured to retain the plurality of balls at intervals in a circumferential direction, the cage being a crown type cage comprising a base portion and a plurality of pillar portions protruded on an axial end face of axially from the base portion, the bails balls being accommodated in spherical pockets formed between the pillar portions; and 
 an annular lubricant guide fixed to in fixed engagement with the engagement groove of the outer ring at an axial end portion of the outer ring and extending towards a shoulder portion the tapered portion of the inner ring, 
 wherein an annular opening portion is formed between an inner circumferential portion of the lubricant guide and the outer circumferential surface of the inner ring to supply lubricating oil into an interior of the ball bearing, and 
 wherein the tapered portion of the inner ring faces an inner circumferential portion of the lubricant guide, 
 wherein the ball bearing is used under an environment in which the lubricating oil is supplied from one side in an axial direction with respect to the balls and is discharged from the other side in the axial direction with respect to the balls, 
 wherein the lubricant guide is provided only on said one a first side in the an axial direction with respect to the balls, the other side being an annular the annular supply opening is formed between the inner circumferential portion of the lubricant guide and the tapered portion of the inner ring to supply lubricating oil into an interior of the ball bearing, and the discharge opening extending is on a second side in the axial direction with respect to the balls and extends radially between the outer ring inner circumferential surface and the inner ring outer circumferential surface to discharge the lubricating oil from the interior of the ball bearing, and 
 wherein the ball bearing is used in an environment in which the lubricating oil is supplied from the first side in the axial direction with respect to the balls and is discharged from the second side in the axial direction with respect to the balls, 
 wherein the base portion of the cage is disposed to face said one the first side in the axial direction; and 
 wherein the inner circumferential portion of the lubricant guide comprises a bent wall extending toward the interior of the bearing; 
 wherein a radial widthwise center of the cage is offset radially inwards relative to a center of each of the balls, 
 wherein the center of each of the balls is offset towards the second side in the axial direction relative to axial widthwise centers of the inner ring and the outer ring, 
 wherein an inside diameter of the lubricant guide is smaller than an inside diameter of the cage, and 
 wherein a shortest distance between the tapered portion of the inner ring and the inner circumferential portion of the lubricant guide is 11% or more of the diameter of each of the balls. 
 
     
     
       2. The ball bearing as set forth in  claim 1 ,
 wherein a radial widthwise center of the cage is offset radially inwards than a center of each of the balls.   
     
     
       3. The ball bearing as set forth in  claim 1 , wherein a center of each of the balls is offset toward the other side in the axial direction than axial widthwise centers of the inner ring and the outer ring. 
     
     
       4. The ball bearing as set forth in  claim 1 , wherein the shoulder portion of the inner ring that faces the inner circumferential portion of the lubricant guide comprises at least one of a tapered cutout portion and a stepped cutout portion. 
     
     
       5. The ball bearing as set forth in  claim 1 , wherein the inner circumferential portion of the lubricant guide comprises a bent wall which is bent toward the interior of the bearing. 
     
     
       6. The ball bearing as set forth in  claim 1 , wherein an edge edges of an inner circumferential portion portions of the spherical pocket pockets of the cage is are chamfered or rounded. 
     
     
       7. The ball bearing as set forth in  claim 1 , wherein an inside diameter of the lubricant guide is equal to or smaller than an inside diameter of the cage, and
 wherein a shortest distance between the outer circumferential portion of the inner ring and the inner circumferential portion of the lubricant guide which form the annular opening portion is 11% or more of the diameter of the ball.   
     
     
       8. The ball bearing as set forth in  claim 1 , wherein the lubricant guide and a housing to which the outer ring is fixed are formed as a one-piece structure.