1. Field of the Invention
The present invention relates to a retainer used in a radial roller bearing that supports a rotating system to which a large radial load (a load in a radial direction) is applied like a power mechanism that is provided in a vehicle such as an automobile or a railroad car. Specifically, the invention relates to the improvement of a one-split resin retainer with a spring that is assembled with a needle (needle roller) bearing and used under environment where fretting is easily generated, or the improvement of a retainer that is used at a portion where lubricating oil is insufficient or a portion that requires an oil passing property, due to the restriction on a guide portion, which guides the end face of a retainer, of a mating member where a bearing is assembled.
2. Description of Related Art
Since a very large load is applied to a rotating system of a power mechanism, which is provided in a vehicle such as an automobile and a railroad car, in a radial direction, a radial roller bearing (hereinafter, referred to as a roller bearing or a bearing), which has excellent load capability against the load, has been widely used in the past as a bearing where a rotating shaft of the rotating system is rotatably supported.
The bearing includes an outer member that includes a cylindrical outer raceway on the inner peripheral surface thereof (for example, an outer race or a housing that is always maintained in an irrotational state, a gear or a roller that is rotatable when being used, or the like); a plurality of rollers (as an example, a plurality of needles or the like) that are rotatably assembled between the outer raceway and the outer peripheral surface (inner raceway) of an inner member (for example, an inner race, a shaft, or the like that is rotatable when being used) that is disposed on the inner diameter side of the outer member; and a retainer in which these rollers are disposed at predetermined intervals (as an example, at regular intervals) in a circumferential direction and are retained and which is assembled with the outer and inner members. Further, the retainer includes a pair of annular portions that are concentrically disposed and face each other with a predetermined interval therebetween; and a plurality of pillar portions that connect these annular portions and form pockets, where the rollers are inserted and rotatably retained, by separating the area between the annular portions into areas in the circumferential direction of the annular portions.
Here, a case where a retainer used in a bearing, which includes an outer race as an outer member and a rotating shaft as an inner member, is assembled with an inner raceway portion of the rotating shaft is assumed as an example. In this case, the retainer is inserted from an end portion of the rotating shaft and is moved to the inner raceway portion of the shaft in the axial direction. At that time, if stepped portions, flange-shaped collar portions, or the like, which have an outer diameter set to be larger than the inner diameter of the retainer, protrude from the outer peripheral surface of the shaft between the end portion of the shaft and the inner raceway, the inner peripheral portion of the retainer interfere with these stepped portions or collar portions. For this reason, it is not possible to move the retainer to the inner raceway portion in the axial direction.
For example, a structure where a split portion is formed at a part of a retainer made of a resin, that is, the structure of a retainer where a pair of annular portions is formed in the shape of a substantially circular ring, which is discontinuous, (in the shape of a segmental circular ring) including an incision at a part thereof (as an example, at one position) and both the annular portions are connected to each other at the incision (cutout portion) by an elastic body (elastic connecting portion) in the form of a spring has been known in the past in order to eliminate the above-mentioned inconvenience (see Patent Literature 1).
An example of the structure of the retainer is shown in FIGS. 8A and 8B. In this case, cutout portions 74a and 74b are formed at a pair of annular portions (rim portions) 72a and 72b of a retainer 70, respectively, and these cutout portions 74a and 74b are positioned so that the phases of the cutout portions are shifted from each other in the circumferential direction. Further, there is provided an elastic connecting portion 76 that connects one end portion (as an example, an end portion positioned below the cutout portion 74a) of one rim portion (as an example, the left rim portion 72a in FIG. 8A) of the pair of rim portions 72a and 72b in the circumferential direction to the other end portion (as an example, an end portion positioned above the cutout portion 74b) of the other rim portion (as an example, the right rim portion 72b) in the form of a spring. That is, the elastic connecting portion 76 is formed across one split portion 70a of the retainer 70, so that the elastic connecting portion divides the split portion 70a into two portions.
Due to this structure, the elastic connecting portion 76 is elastically deformed to both sides in the circumferential direction when a force is applied to the retainer 70 in a direction where the size of the split portion 70a is increased. Accordingly, it is possible to stretch the elastic connecting portion (a state shown in FIG. 8B). As a result, it is possible to increase the size of the split portion 70a of the retainer 70, that is, to increase the diameter of the retainer 70. Meanwhile, when a predetermined force applied to the retainer 70 (a force applied in the direction where the size of the split portion 70a is increased) is removed, the size of the elastic connecting portion 76 is reduced to an original state by an elastic restoring force. Accordingly, it is possible to return the split portion 70a of the retainer 70 (the diameter of the retainer 70) to the original state (a state shown in FIG. 8A).
Meanwhile, the diameter of the retainer 70 (the size of the split portion 70a) is not increased in excess of the limit of the stretched length of the elastic connecting portion 76, and the elastic connecting portion 76 also has a function of preventing the diameter of the retainer 70 (the size of the split portion 70a) from being excessively increased.
Accordingly, for example, even if stepped portions, flange-shaped collar portions, or the like, which have an outer diameter set to be larger than the inner diameter of the retainer, protrude from the outer peripheral surface of the shaft between the end portion of the shaft and the inner raceway as described above, it is possible to smoothly move the retainer 70 to the inner raceway portion of the rotating shaft in the axial direction without the interference with the stepped portions or the collar portions by temporarily increasing the size of the split portion 70a of the retainer 70 (temporarily increasing the diameter of the retainer 70).
Further, since rollers are retained in the pockets of the retainer, the increase of rotational resistance, seizure, or the like, which is caused by friction generated due to the contact between the rollers when the rollers roll between the raceways (the outer and inner raceways), is prevented. In addition, bearing lubrication (oil lubrication or grease lubrication) is generally performed in combination in order to more effectively prevent the increase of rotational resistance, seizure, or the like. For this reason, in the past, there have been known the structures of various retainers of which lubrication performance is improved in order to improve lubrication efficiency at the time of bearing lubrication (see Patent Literature 2 to Patent Literature 4).
For example, in the structures of the retainers disclosed in Patent Literature 2 to Patent Literature 4, notches or grooves, which communicate with pockets, are formed on the outer peripheral portions of annular portions in an axial direction in order to increase the flowability of a lubricant and improve the lubrication performance of the retainers.