CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2019-203171 filed on Nov. 8, 2019, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a rolling bearing and a cage.

2. Description of Related Art

A rolling bearing includes an inner ring, an outer ring, a plurality of rolling elements provided between the inner ring and the outer ring, and an annular cage. In a case of a ball bearing the rolling element of which is a ball, a so-called snap cage made of resin is used. A rolling bearing that uses a snap cage has such an advantage that a region (non-stirring region) where lubricant such as grease is not stirred is large and shearing of the grease is restrained. Japanese Unexamined Patent Application Publication No. 2003-35317 (JP 2003-35317 A) describes a rolling bearing including a snap cage.

SUMMARY

The snap cage includes an annular body placed closer to a first side in the axial direction than rolling elements, and a plurality of cage prongs. The cage prongs are provided to extend to a second side in the axial direction from the annular body. Accordingly, when the rolling bearing rotates, distal-end-side portions of the cage prongs deform toward an outer ring side due to centrifugal force. Particularly, when the rotation speed of the rolling bearing is high, there is such a possibility that the cage prongs partially make contact with the outer ring, and the cage is worn unevenly.

In view of this, an object of this disclosure is to achieve a cage the cage prongs of which are hard to deform against centrifugal force and to prevent a decrease in the strength of the cage prongs.

A rolling bearing according to a first aspect of this disclosure includes an inner ring, an outer ring, a plurality of rolling elements, and an annular cage. The rolling elements are provided between the inner ring and the outer ring. In the cage, the rolling elements are held at intervals in the circumferential direction of the cage. The cage includes an annular body placed closer to a first side in the axial direction of the cage than the rolling elements, and a plurality of cage prongs provided to extend to a second side in the axial direction from the annular body. Each of the cage prongs includes a lack portion provided from a first side of the each of the cage prongs to a second side of the each of the cage prongs in the axial direction such that the lack portion is opened to the second side in the axial direction and along a radial direction of the cage. The each of the cage prongs includes a pair of cage prong bodies such that the cage prong bodies are provided on both sides of the lack portion in the circumferential direction and make contact with a corresponding one of the rolling elements. A stiffening rib is provided between the cage prong bodies.

In this rolling bearing, the lack portion is formed in the cage prong, so that the weight of the cage prong is reduced, thereby making it possible to decrease centrifugal force to be applied to the cage. When the rolling bearing rotates, the rolling element makes contact with the cage prong from the circumferential direction. Although the strength of the cage prong decreases due to the lack portion, the stiffening rib can prevent a decrease in the strength of the cage prong. Thus, the cage prong can hardly deform due to the centrifugal force by reducing the weight of the cage prong, and the decrease in the strength of the cage prong can be prevented by the stiffening rib.

Further, in the above aspect, the inner ring may include an inner ring raceway with which balls as the rolling elements make rolling contact, and the cage may include guide portions configured to position the cage by making contact with the inner ring raceway. In this configuration, since the balls make rolling contact with the inner ring raceway, machining such as grinding is performed on the inner ring raceway, for example. When the guide portions are brought into contact with the inner ring raceway configured as such, the cage is stably guided.

Further, in the above aspect, the stiffening rib may be provided at a position closer to the inner side in the radial direction between the cage prong bodies. In this configuration, in comparison with a case where the stiffening rib is provided at a position closer to the outer side in the radial direction, the volume of the lack portion can be made large. This heightens an effect to reduce the weight of the cage prong.

Further, in the above aspect, the stiffening rib may include a first rib portion provided on the first side in the axial direction and connecting the annular body to the cage prong bodies, and a pair of second rib portions provided at an interval in the circumferential direction so as to extend to the second side in the axial direction from the first rib portion, the second rib portions being connected to the cage prong bodies. In this configuration, a part of the stiffening rib between the second rib portions is lacked, so that an increase in weight by the stiffening rib can be restrained. Besides, the cage prong bodies are connected to the annular body via the first rib portion and the second rib portions, so that the stiffening rib can sufficiently have a function as a stiffener for the cage prong bodies.

Further, a cage according to a second aspect of this disclosure includes an annular body and a plurality of cage prongs. The annular body is placed closer to a first side in the axial direction of the cage than rolling elements provided in a rolling bearing. The cage prongs are provided to extend to a second side in the axial direction from the annular body. Each of the cage prongs includes a lack portion provided from a first side of the each of the cage prongs to a second side of the each of the cage prongs in the axial direction such that the lack portion is opened to the second side in the axial direction and along the radial direction of the cage. The each of the cage prongs includes a pair of cage prong bodies such that the cage prong bodies are provided on both sides of the lack portion in the circumferential direction of the cage and make contact with a corresponding one of the rolling elements. A stiffening rib is provided between the cage prong bodies.

In the cage, the lack portion is formed in the cage prong. Accordingly, the weight of the cage prong is reduced, thereby making it possible to decrease centrifugal force to be applied to the cage. When the rolling bearing including the cage rotates, the rolling element makes contact with the cage prong from the circumferential direction. Although the strength of the cage prong decreases due to the lack portion, the stiffening rib can prevent a decrease in the strength of the cage prong. Thus, the cage prong can hardly deform due to the centrifugal force by reducing the weight of the cage prong, and the decrease in the strength of the cage prong can be prevented by the stiffening rib.

With the aspects of this disclosure, the cage prongs of the cage can hardly deform, and the decrease in the strength of the cage prongs can be prevented.

