Cylindrical roller bearing

Abstract

A cylindrical roller bearing includes at least one outer ring with a raceway, an inner ring with a raceway, and a plurality of cylindrical roller elements rollable along the raceways of the inner ring and the outer ring. The raceway of the inner ring has an at least partly crowned profile, the crowned profile having a crowning radius R and is formed such that: 25 L.sup.2/D<R<55 L.sup.2/D, in which L is the length of each one of the cylindrical roller elements and D is the diameter of each one of the cylindrical roller elements.

Claims

1. A cylindrical roller bearing comprising: at least one outer ring with a raceway, an inner ring with a raceway, a plurality of cylindrical roller elements rollable along the raceways of the inner ring and the outer ring, and a roller guided cage arranged radially inwardly of a pitch diameter of the cylindrical roller elements and spaced radially outwardly from the inner ring, the cage including two side rings and a plurality of cage bars connecting the side rings so as to form pockets, the cylindrical roller elements being accommodated within the pockets, wherein the raceway of the inner ring has an at least partly crowned profile, the crowned profile having a crowning radius R and is formed such that:
25L.sup.2/D<R<55L.sup.2/D, wherein L is the length of each one of the cylindrical roller elements and D is the diameter of each one of the cylindrical roller elements; and wherein the inner ring raceway formed with the crowned profile having the crowning radius R and the roller guided cage being spaced radially outwardly from the inner ring enables an angular misalignment () in the full range of +/1 and an axial displacement in the full range of 0% to 25% of an axial length of the inner ring.

2. The cylindrical roller bearing according to claim 1, wherein each one of the cylindrical roller elements is in line contact with the raceway of the inner ring and with the raceway of the outer ring, the axial extent of the line contact of each one of the cylindrical roller elements at the raceway of the inner ring is shorter than the axial extent of the line contact of each one of the cylindrical roller elements at the raceway of the outer ring.

3. The cylindrical roller bearing according to claim 1, wherein the entire raceway of the inner ring has a crowned profile.

4. The cylindrical roller bearing according to claim 1, wherein the crowning radius of the crowned profile is constant over the axial length of the raceway or the crowning radius of the crowned profile varies over the axial length of the raceway.

5. The cylindrical roller bearing according to claim 1, wherein the cylindrical roller bearing has a filling degree FG of greater than 80%, the filling degree being defined by:
FG=D/(P*sin(/Z), wherein D is the diameter of each one of the cylindrical roller elements, P is the pitch diameter of the cylindrical roller elements, and Z is the number of the cylindrical roller elements.

6. The cylindrical roller bearing according to claim 5, wherein the filling degree is greater than 87%.

7. The cylindrical roller bearing according to claim 1, wherein the outer ring has first and second axial ends, a flange located at the first axial end, the flange axially retaining the cylindrical roller elements at the first axial end, and a groove at the second axial end, the groove being adapted to accommodate a retaining ring for axially retaining the cylindrical roller elements at the second axial end.

8. The cylindrical roller bearing according to claim 1, wherein the inner ring can accommodate an axial displacement of up to 25% of the bearing width.

9. The cylindrical roller bearing according to claim 1, wherein the entire raceway of the inner ring has a crowned profile and the crowning radius of the crowned profile is constant over the entire axial length of the inner ring.

10. The cylindrical roller bearing according to claim 1, wherein the raceway of the inner ring has two axial sides and a middle part, the crowning profile being arranged at the two axial sides and the middle part is flat.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) In the following, preferred embodiments of the invention are described in relation to the drawings, wherein the drawings are exemplarily only, and are not intended to limit the scope of protection. The scope of protection is defined by the accompanied claims, only.

(2) The figure show:

(3) FIG. 1: a schematic cross section of a cylindrical roller bearing according to a preferred embodiment

(4) FIG. 2: a schematic cross section of a cylindrical roller bearing illustrating an axial displacement; and

(5) FIG. 3: a schematic cross section of a cylindrical roller bearing illustrating an angular misalignment.

DETAILED DESCRIPTION OF THE INVENTION

(6) In the following same or similar functioning elements are indicated with the same reference numerals.

(7) FIG. 1 illustrates a schematic cross section of a cylindrical roller bearing 1 having an inner ring 2 and an outer ring 4 between which a plurality of roller elements 6 are arranged.

(8) The roller elements 6 in the illustrated embodiment are cylindrical roller elements which accommodated in a cage 8. The cage 8 is adapted to hold the roller elements 6 and maintain a constant distance between them. As can be further seen in FIG. 1, the cage 8 is a so-called high capacity cage, which is guided by the roller elements. The cage bars (not illustrated) are arranged well below the pitch diameter P of the rollers 6. Thus, the illustrated cylindrical roller bearing 1 is a nearly full compartment bearing. The new design allows for a roller filling degree FG of more than 80%, preferably more than 87%, with FG=D/(P*sin(/Z), with D being the diameter of the roller element, P the pitch diameter and Z, the number of roller elements. Other arrangements are also possible.

(9) The outer ring 4 has at a first axial side 10 a flange 12, and at the second axial side 14 a groove 16 in which a retaining ring 18 is accommodated. The flange 12 and the retaining ring 18 allow for an axial restriction of the cylindrical roller elements 6. During disassembling, the retainer ring may be easily detached from the outer ring 4, which in turn allows for a facilitated and non-destroying disassembling of the complete bearing 1 during service.

(10) As can be further seen in FIG. 1, the inner ring 2 has a crowned profile having a crowning radius R. The crowning radius R may be constant or can vary over the axial length L.sub.IR of the inner ring 2. In the illustrated embodiment, the crowning radius is constant and may be in the range of 25 L.sup.2/D<R<55 L.sup.2/D, wherein L is the length of the roller element and D is the diameter of the roller element. This crowning radius R allows for an angular misalignment of up to +/1, or at least +/0.5 (see FIG. 3).

(11) The crowning profile of the inner ring 2 also allows for axial displacements of up to 25%, at least up to 15%, of the bearing width given by the axial length L.sub.IR of the inner ring 2 (see FIG. 2). This is due to the fact that even if the inner ring has a crowning profile, the profile remains flat enough for providing a sufficiently long line contact with the roller elements and therefore a sufficient support during the axial displacement.

(12) Additionally or alternatively, the inner ring 2 may have a crowning profile which is only arranged at the axial sides 22 and 24 of the inner ring 2, wherein the middle part 26 of the inner ring 2 may remain, preferably almost, flat. This allows for a large load capacity, as a line contact between the roller element and the inner ring may be adapted to be maximal.

(13) In summary, the above proposed cylindrical roller bearing combines the possibility to separate the inner ring from the outer ring and roller elements with the possibility to angular misalignment together with axial displacement. This is achieved by providing an inner ring with a crowned profile which has traditionally been assumed to increase contact stresses, unduly. However, the careful adaption of the crowning radius ensures that contact stresses may be avoided, and angular misalignments in the order of degrees instead of minutes are allowed.

REFERENCE NUMERALS

(14) 1 cylindrical roller bearing 2 inner ring 4 outer ring 6 cylindrical roller element 8 cage 10 first axial side of outer ring 12 flange 14 second axial side of outer ring 16 groove 18 retaining ring 22 first axial side of inner ring 24 second axial side of inner ring 26 middle part of the inner ring P pitch diameter misalignment angle S axial displacement L.sub.IR length of the inner ring L length of the roller element D diameter of the roller element