Roller bearing

1. Field of the Invention

The present invention relates to a roller bearing used in an internal combustion engine and an internal combustion engine using the same.

2. Background Art

In an internal combustion engine, for example, in a case where a camshaft is rotatably supported in a cylinder head, sliding bearings are generally used. In recent years, however, the actual situation is such that attention has been focused on less fuel-consuming internal combustion engines from the viewpoints of such as effective utilization of resources and reduction of carbon dioxides. Accordingly, attempts have been made to further reduce the power loss in internal combustion engines by changing sliding bearings to rolling bearings whose drag resistance is generally smaller (refer to JP-A-8-128306). In particular, in the so-called DOHC-type internal combustion engines and V-type internal combustion engines, the number of camshafts becomes relatively numerous in the light of their structures, so that it is expected that the change of the rolling bearings leads to some degree of improvement in fuel consumption.

Incidentally, a pair of cam lobes are generally formed in each cylinder, and journal portions which are supported by rolling bearings are disposed between the cam lobes or between the cam lobe and a large-diameter end portion. Therefore, there is a problem in that ordinary rolling bearings cannot be fitted on the journal portions by passing the cam lobes and the like which project more radially outward. Accordingly, it has been conceived to circumferentially split retainers of rolling bearings and to build these split retainers onto the journal portions from the radially outer side without passing the cam lobes and the like, in the same way as conventionally used sliding bearings (refer to JP-A-2001-12214).

However, it is desirable to build races on the cylinder head and the cap so as to secure raceway surfaces for the rollers to roll. For this reason, it is considered necessary to circumferentially split the races and incorporate them in the same way as the retainers. Nevertheless, since the races themselves are generally thin cylinders, if they are split circumferentially and are merely built on the cylinder head and the cap, there is a possibility of the races rotating in circular holes formed by the cylinder head and the cap and coming off in an axial direction. A similar problem occurs in a case where a crankshaft is supported between a cylinder block and a bearing cap.

In the case where the races and retainers are thus built in by being split, problems, such as the securing of roundness, are expected to occur which are essentially different from those of the case where cylindrical races are built in.

The present invention has been devised in view of the above-described problems, and its object is to provide a roller bearing which is capable of appropriately supporting a camshaft or a crankshaft with lower friction, as well as an internal combustion engine using the same.

The invention provides a roller bearing for rotatably supporting a rotating shaft of an internal combustion engine between a main body and a cap of the internal combustion engine, the roller bearing includes: a plurality of rollers; a retainer which is circumferentially splittable and supports the plurality of rollers; and an outer race which is circumferentially splittable and forms a raceway surface for the plurality of rollers; wherein the retainer is split into a plurality of retaining members; the outer race is split into a plurality of race plates; and at least one of the race plates is provided with one of a projection and a cavity to be engaged with one of the main body and the cap to restrict a relative movement between the one of the race plates and the one of the cylinder head and the cap.

The invention provides a roller bearing for rotatably supporting a rotating shaft of an internal combustion engine between a main body and a cap of the internal combustion engine, the roller bearing includes: a plurality of rollers; a retainer which is circumferentially splittable and supports the rollers; and an inner race which is circumferentially splittable and forms a raceway surface for the rollers; wherein the retainer is split into a plurality of retaining members; the inner race is split into a plurality of race plates; and at least one of the race plates is provided with one of a projection and a cavity to be engaged with the rotating shaft to restrict a relative movement between the one of the race plates and the rotating shaft.

The invention provides a roller bearing for rotatably supporting a rotating shaft of an internal combustion engine between a main body and a cap, including: a plurality of rollers; a retainer which is circumferentially splittable and supports the rollers; and an outer race which is circumferentially splittable and forms a raceway surface for the rollers; wherein the retainer is split into a plurality of split retaining members; the outer race is split into a plurality of split race plates; the race plates are disposed into concave portions of the main body and the cap; and the race plates in a free state have greater radii of curvature than radii of curvature of the concave portions.

The invention provides a method of manufacturing a race plate in a roller bearing for an internal combustion engine, wherein the roller bearing includes a plurality of rollers, a retainer which is circumferentially splittable into a plurality of retaining members for supporting the rollers, and an outer race which is circumferentially splittable into a plurality of race plates for forming a raceway surface for the rollers, the method including: stamping out a plate material such that at least one end thereof is formed in such a shape as to be complementary to an end of another plate material; surface pressing at least one end side of the stamped-out plate material; rolling the plate material; subjecting the plate material to heat treatment; and subjecting the plate material to barreling.

The invention provides a method of manufacturing a retainer in a roller bearing for an internal combustion engine, wherein the roller bearing includes a plurality of rollers, a retainer which is circumferentially splittable into a plurality of retaining members for supporting the rollers, and an outer race which is circumferentially splittable into a plurality of race plates for forming a raceway surface for the rollers, the method includes: stamping out a plate material such that the width of a column portion located closest to an end portion formed in the retainer is narrower than the width of other column portions; rolling the plate material; subjecting the plate material to heat treatment; and subjecting the plate material to at least one of copper plating and silver plating.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more readily described with reference to the accompanying drawings:

FIG. 1 is an exploded view of a cylinder head of an internal combustion engine in accordance with an embodiment of the invention;

FIG. 2 is a partially enlarged view of a camshaft;

FIG. 3 is a perspective view of a race plate and a cap illustrating a modification of this embodiment;

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