Roller bearing

Details Roller bearing Roller bearing

2000-12-20

2003-02-04

Schwartz, Christopher P. (Department: 3613)

Bearings

Rotary bearing

Antifriction bearing

C384S571000

Reexamination Certificate

active

06513985

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a roller bearing and, in particular, to a roller bearing such as a cylindrical roller bearing and a conical roller bearing which is able to maintain proper lubrication between the end faces of a large number of rollers and the collar portion of the roller bearing.
2. Description of the Related Art
FIG. 5
shows a conventional conical roller bearing
50
. This conical roller bearing
50
includes an outer race
52
with an outer raceway
51
formed on the inner peripheral surface thereof, an inner race
54
with an inner raceway
53
formed on the outer peripheral surface thereof, a large number of rollers
55
respectively interposed between the outer and inner raceways
51
and
53
, and a collar portion
56
formed so as to extend along the axial-direction end portion of the inner raceway
53
.
Each of the outer and inner raceways
51
and
53
is crowning machined to thereby have a bus consisting of a concave-shaped arc line. By the way, in the conical roller bearing
50
, differently from a self-aligning roller bearing, the center C
1
of the bus of the outer raceway
51
is set at an arbitrary position which is shifted from the axis C of the conical roller bearing
50
.
Each of the rollers
55
is structured in the following manner: that is, a rolling surface thereof is formed substantially in a conical shape which includes a convex-shaped arc line as a bus, a large-diameter end face
57
thereof is formed as a convex-shaped spherical surface, and a small-diameter end face
58
thereof is formed so as to have an arbitrary surface shape.
These rollers
55
are respectively arranged in such a manner that their respective rotation axes C
2
(about which they can be rotated) extend along the bus of a first virtual conical surface having a vertex C
3
at a given position existing along the extension line of the axis C of the conical roller bearing
50
.
In the thus structured conical roller bearing
50
, escape portions
60
, each having a section substantially three quarters (¾) of which are composed of a circle, are successively formed along an entry corner existing between the inner raceway
53
and the collar surface
59
of the collar portion
56
.
And, as shown in
FIG. 6
, in the conical roller bearing
50
that rotates normally, due to a previously given pre-load or a component of a bearing load, the large-diameter end face
57
consisting of a convex-shaped spherical surface is slidingly surface contacted with the collar surface
59
consisting of a conical surface through a contact area A having a given area (see hatching shown in FIG.
6
).
By the way, generally, the outer raceway
51
, inner raceway
53
and rollers
55
of the conical roller bearing
50
are formed such that their buses are respectively composed of arc lines; and, therefore, in case where an excessive load, a biased load, or sudden acceleration is applied to the conical roller bearing
50
, a strange phenomenon called a skew or a tilt is easy to occur in the conical roller bearing
50
.
Here, the “skew” means a phenomenon in which the rotation axis C
2
of each roller
55
is inclined or skewed along the spiral direction of the above-mentioned first virtual conical surface. On the other hand, the “tilt” means a phenomenon in which the rotation axis C
2
of each roller
55
is inclined or tilted with respect to the bus of the above-mentioned first virtual conical surface as well as in the other inclined directions than the inclined direction of the skew phenomenon.
Now,
FIGS. 7A and 7B
show two states in which a skew and a tilt occur in the conventional conical roller bearing
50
, respectively. That is, as shown in
FIG. 7A
, in case where a skew occurs in the conical roller bearing
50
, since the direction of the large-diameter end face
57
consisting of a three-dimensional curved surface varies with respect to the collar surface
59
consisting of a two-dimensional curved surface, the contact area A is moved to the edge portion side of the large-diameter end face
57
as well as to the outside diameter side of the collar surface
59
(see hatching shown in FIG.
7
A).
Then, in the conical roller bearing
50
, in case where the skew occurs excessively, there is a possibility that the contact area A can deviate from the outside diameter side of the collar surface
59
and thus the contact area between the large-diameter end face
57
and collar surface
59
can be reduced (see a two-dot chained line shown in FIG.
7
A).
In this case, when compared with a case where the conventional conical roller bearing
50
rotates normally, since the contact pressure of the contact area A (that is, pressure per unit area) increases, there is a fear that scoring or seizure can occur in one or both of the large-diameter end face
57
and collar surface
59
.
On the other hand, as shown in
FIG. 7B
, in case where a tilt occurs in the conical roller bearing
50
(see hatching shown in FIG.
7
B), similarly to the case in which the skew occurs, the contact area A is moved to the outside diameter side of the collar surface
59
.
Therefore, in the conventional conical roller bearing
50
, in the case of occurrence of an excessive tilt as well, the contact area A is moved to the outside diameter side of the collar surface
59
, thereby raising a fear that scoring or seizure can occur in one or both of the large-diameter end face
57
and collar surface
59
.
Also, in the conventional conical roller bearing
50
, for a structural reason that the large-diameter end face
57
consisting of a spherical surface is slidingly surface contacted with the collar surface
59
consisting of an arc surface by preload, the contact area A has an upper limit, whereby it is difficult to reduce the contact pressure of the contact area A.
SUMMARY OF THE INVENTION
The present invention aims at eliminating the drawbacks found in the above-mentioned conventional conical roller bearing. Accordingly, it is an object of the invention to provide a roller bearing in which scoring or seizure is hard to occur in rollers and a collar portion respectively forming the components of the roller bearing.
In attaining the above object, according to a first aspect of the invention, there is provided a roller bearing, including: an outer race with a concave-shaped outer raceway formed on the inner peripheral surface thereof; an inner race with a concave-shaped inner raceway formed on the outer peripheral surface thereof; a plurality of substantially cylindrical-shaped rolling elements respectively interposed between the outer raceway and the inner raceway; and, a collar portion formed so as to extend along one of an axial-direction end portion of the outer raceway and an axial-direction end portion of the inner raceway. The outer peripheral surface of each of the rolling elements being formed of a convex-shaped bus, and the end faces of the rolling elements are formed as a convex-shaped spherical surface. The central portion of one of the outer and inner raceways, and the outer peripheral surface of each of the rolling elements is formed of a first bus which has a given radius of curvature and, two end portion sides adjoining the central portion are each formed of a second bus having such a radius of curvature that causes the two end portion sides to part away from the other of the outer and inner raceways, and the outer peripheral surface of each of the rolling elements. The collar surface of the collar portion is formed as a concave-shaped spherical surface.
Also, according to a second aspect of the invention, there is provided a roller bearing, including: an outer race with a convex-shaped outer raceway formed on the inner peripheral surface thereof; an inner race with a convex-shaped inner raceway formed on the outer peripheral surface thereof; a plurality of substantially cylindrical-shaped rolling elements respectively interposed between the outer raceway and the inner raceway; and, a collar portion formed so as to extend along one of an axial-directio

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