Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-07-30
2003-06-24
Butler, Douglas C. (Department: 3683)
Bearings
Rotary bearing
Antifriction bearing
C384S572000
Reexamination Certificate
active
06582131
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. §119 with respect to German Application No. G 200 13 305.5 filed on Jul. 31, 2000, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
This invention generally relates to roller bearings. More particularly, the present invention pertains to a cylindrical roller bearing having an outer race, an inner race, a plurality of rolling elements arranged between outer race and inner race, and at least one cage having a number of locating pockets corresponding to the number of rolling elements.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,428,628 discloses a cylindrical roller bearing possessing a split inner race construction. The two parts forming the inner race are axially assembled so that a groove is formed between them to receive the cage which is in the form of a disk. The cage guides the individual cylindrical rollers which on the outside are surrounded by the outer race.
The drawback associates with this cylindrical roller bearing, as well as many other cylindrical roller bearings, is that the outer race or the inner race must have a split construction to enable the cage to be mounted. This involves significant production costs as well as complexity in the assembly of the bearing.
Cage configurations in which the cage is assembled from individual segments are known. GB 799 126 discloses such a cage construction. Although using this type of cage in a cylindrical bearing makes it possible to construct the race which is provided with the groove as a single piece, it also involves the potential risk that the cage might crack under load at the joints.
A need thus exists for a cylindrical roller bearing that allows a one-piece construction of the outer or the inner race, while at the same time ensuring sufficient stability of the disk cage in operation.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a cylindrical roller cage includes an outer race, and inner race, a plurality of rolling elements arranged between the outer race and the inner race, and at least one cage having a plurality of locating pockets corresponding to the number of rolling elements. The cage is ring-shaped and is arranged in a groove in the outer race or the inner race. The cage is interrupted at least at one circumferential point to define two ends of the cage at the breakpoint that form a hook-type connection having at least two cooperating hook elements which interact in a complementary manner by way of an undercut as viewed in the circumferential direction. The axial direction of the hook elements forms an angle of 15° to 75° with the circumferential direction at the breakpoint.
Thus, according to the present invention, a ring-shaped cage is provided with a hook-type connection by way of which the cage can be fixed after being mounted in the groove of the inner race or the outer race. With respect to its axial direction, the hook element is arranged in such a way that it lies against the cage at an angle to the tangent. Since detaching the hook connection thus requires shifting in both the radial and circumferential direction, the cage offers great resistance against accidental opening when the bearing is in operation.
The two ends of the cage can be configured in a way that permits the ends to be snapped together at the break point. Also, axially extending cross-holes can be formed in the cage and spaced apart along the circumference of the cage. These holes permit lubricant for the bearing to collect and/or can serve to discharge excess lubricant.
According to a preferred form of the invention, two ring-shaped cages are arranged in the peripheral area of the rolling elements adjacent opposite axial ends of the rolling elements. Advantageously, the junction between the raceway of the outer race or the inner race and the cage (or the groove formed in the inner or outer race) can be at least partially cambered to avoid stress concentration at the edges. This camber can be determined based on a so-called logarithmic profile as known in the art. The material for the proposed cage is preferably plastic or brass.
In accordance with another aspect of the invention, a cylindrical roller bearing includes an outer race, an inner race, a plurality of rolling elements arranged between the outer race and the inner race, and at least one annular cage having a plurality of locating pockets in which are positioned the rolling elements, with the cage being interrupted at least at one circumferentially located breakpoint to define two ends of the cage at the breakpoint. Each end of the cage has an engaging element, with the engaging element at one cage end engaging the engaging element at the other cage end to secure together the cage ends. The engaging elements extend in an axial direction forming an acute angle with a tangent to a circumference of the cage.
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Burns Doane , Swecker, Mathis LLP
Butler Douglas C.
Pezzlo Benjamin A
SKF GmbH
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