WO2013189545A1

WO2013189545A1 - Rolling bearing comprising a housing having two parts

Info

Publication number: WO2013189545A1
Application number: PCT/EP2012/062026
Authority: WO
Inventors: Frank Berens; Olivier Verbe; Stéphane CORDIER; Yves-André LIVERATO; Thierry Adane
Original assignee: Aktiebolaget Skf
Priority date: 2012-06-21
Filing date: 2012-06-21
Publication date: 2013-12-27

Abstract

Rolling bearing comprising an inner ring (1), an outer ring(2), at least one row of rolling elements(3) disposed between raceways (11a, 11b, 17a, 17b) provided on the inner and outer rings (1, 2), and at least one annular housing (5) inside which at least one of the rings (1) is arranged, said one ring (1) comprising two separate parts (1a, b), each separate part (1a, 1b) having two radial surfaces (22a, 31a) oriented towards the outside, the housing (5) comprising two annular distinct parts (22, 23) for retaining the separate parts(1a, 1b) of said one ring(1). A first part (22) of the housing (5) comprises a first axial cylindrical portion(26) axially extending towards a first radial surface (22a) of one separate part (1a) of said one ring (1) and the second part (23) of the housing (5) comprises a second axial cylindrical portion (29) in radial contact with said separate part (1a) and said first axial cylindrical portion(26) of the first part (22).

Description

Rolling bearing comprising a housing having two parts

The present invention relates to rolling bearings, in particular to rolling bearings having an inner ring and an outer ring with one or more rows of rolling elements held by a cage between raceways provided in the two rings . The rolling elements may, for example, be balls . The rolling bearings may be, for example, those used in industrial electric motors or in motor vehicle gearboxes. In such applications, the bearings are mainly lo aded radially, often with relatively weak load compared to the capacity o f the bearings used. The rotational speeds in such applications are o f the order of 3000 revo lutions/minute.

Patent application EP 2 205 878 describes a rolling bearing having an inner and an outer ring both made in two parts and two annular housings each enclosing one of said rings . However, in such application, it is difficult to axially preload the parts of the rings.

Patent US 3 , 876,266 discloses a rolling bearing comprising an inner ring, an outer ring made in two parts, a housing ho lding the two parts of the said ring and a row of balls held by a cage . One of the parts of the outer ring, together with the housing, defines a space inside which an axially prelo aded resilient element is housed.

This document also discloses a method of manufacturing such rolling bearings comprising the steps of inserting the rolling element into the associated cage and mounting this subassembly on the inner ring. Then positioning the two parts of the outer ring around the row of balls, mounting this subassembly and the resilient preloaded element in an L-shaped housing having an outer cylindrical part and fo lding said cylindrical part over one clo sed space and one ring until it enclo ses said one ring and said rolling elements. Given the way these rolling bearings are manufactured, and particularly the fact that the housing is fo lded over to form a second radial plate, it is relatively difficult to guarantee the desired axial clearance or, the predefined axial preload. Furthermore, it is necessary to provide a resilient axial preloaded element, which adds to the cost of the rolling bearing.

Patent application FR 2 945 090 so lve these problems by proposing a rolling bearing comprising a housing made of two distinct parts fixed together. The housing comprises two radial flanges for axially retaining the parts of the outer ring and an axial cylindrical portion connected to one of the radial flanges and in radial contact with the parts of said outer ring and extending radially outwards by a radial proj ection. One of the radial flanges is fixed to the radial proj ection.

However, such a rolling bearing needs a specific reception ho le for the rolling bearing having a stepped shape. Furthermore, when assembling such a ro lling bearing, a slightly deformation o f the outer surface of the axial cylindrical portion may modify the positioning o f the two separate parts of the outer ring. Such a ro lling bearing does not prevent so lid and liquid po llutants from entering between the flanges and the radial proj ection.

Moreover, such a rolling bearing has a high weight and radial dimension, which increases the design and transport costs of the rolling bearing.

One aim o f the present invention is therefore to overcome the aforementioned drawbacks.

It is a particular object of the present invention to provide a rolling bearing o f simple design, that is easy to assemble, economical, and in which the desired clearance or axial preload can easily be obtained during the assembly operations and maintained once the bearing has been assembled.

It is also an obj ect of the present invention to provide a rolling bearing having a good radial stiffness and which is able to operate for a long time in both an effective and economic manner.

Another obj ect of the invention is to provide a rolling bearing having its weight and radial dimensions reduced. In one embodiment, a ro lling bearing comprises an inner ring, an outer ring, at least one row of rolling elements disposed between raceways provided on the inner and outer rings, and at least one annular housing inside which at least one of the rings is arranged. Said one ring comprises two separate parts, each separate part having two radial surfaces oriented towards the outside. The housing comprises two annular distinct parts for retaining the separate parts of said one ring.

A first part of the housing comprises a first axial cylindrical portion axially extending towards a first radial surface of one separate part of said one ring and the second part of the housing comprises a second axial cylindrical portion in radial contact with said separate part of said one ring and said first axial cylindrical portion o f the first part.

Advantageously, the first axial cylindrical portion of the first part of the housing is in axial contact with said first radial surface o f one separate part of said one ring.

Each annular distinct parts may comprise an axial cylindrical portion and a radial flange extending radially from the axial cylindrical portion towards the other ring, each radial flange being in axial contact with a second radial surface of one separate part of said one ring, opposite to the first radial surface o f said one ring and defining with one o f the separate parts of said one ring a closed space.

For example, at least one of said clo sed spaces is adapted to contain a lubricant and act as a lubricant reservoir.

Advantageously, the rolling bearing comprises passage means allowing the lubricant contained in the clo sed spaces to flow towards the rolling elements .

Advantageously, each separate part comprises at least one axial cylindrical portion extending axially from a central portion towards the outside . The axial cylindrical portion end defines a radial surface. Advantageously, the central portion o f each separate part comprises a radial portion, an edge portion and by a toroidal portion defining the raceways

The passage means for the lubricant may comprise axial ho les provided in the thickness of the radial portion of at least one o f the two separate parts of said one ring.

The annular distinct parts of the housing have been, for example, manufactured by cutting and pressing a metal sheet.

In another embodiment, the rolling bearing comprises a second annular housing surrounding the other ring and said other ring comprises two separate parts, the second housing comprising two annular distinct parts for retaining the separate parts of said other ring, the first part of the second housing comprises a first axial cylindrical portion in radial contact with said separate parts of said other ring and the second part of the second housing comprises a second axial cylindrical portion in radial contact with said first axial cylindrical portion of the first part of the second housing.

Advantageously, the first part of the second housing comprises a radial flange extending radially from the first axial cylindrical portion towards said one ring and defining with one o f the separate parts of said other ring a first closed space and the second part of the second housing comprises a radial flange extending radially from the second axial cylindrical portion towards said one ring and defining with one o f the separate parts of said other ring a second clo sed space.

For example, at least one of the closed spaces is adapted to contain a lubricant and act as a lubricant reservoir, and in which at least one of said separate parts of said other ring comprises passage means for the lubricant contained in the closed space to flow towards the rolling elements .

The ro lling bearing may comprise fixing means for fixing together the annular distinct parts of each housing, such as, for example, welds or brazing or glue . In one embodiment, said one ring is the inner ring and said other ring is the outer ring.

Each separate part of at least one of the rings can be heat treated.

In an embodiment, the rolling bearing comprises an axial spacer in axial contact between the radial portions o f the two separate parts of at least one of the rings having two separate parts .

The present invention will be better understood from studying the detailed description o f a number of embodiments considered by way o f entirely non-limiting examp les and illustrated by the attached drawings in which:

Figure 1 is an axial half-section o f the rolling bearing according to the invention, in a first embo diment;

Figure 2 is an axial half-section o f a second embodiment ; and

Figure 3 is an axial half-section o f a third embodiment. In the further description, terms "outer" and inner" are defined with respect to the rotational axis X-X' o f the rolling bearing illustrated on the figures, where the term "inner" means clo ser to the rotational axis X-X ' o f the rolling bearing then term "outer".

Referring first to Figure 1 , which illustrates an embodiment of a rolling bearing 1 according to the invention; said bearing comprises an inner ring 1 , an outer ring 2, a row of rolling elements 3 consisting, in the example illustrated, of balls, held by a cage 4 between the inner ring 1 and the outer ring 2 and two annular housings 5 , 6 respectively enclosing the inner ring 1 and the outer ring 2.

The inner ring 1 comprises two separate parts l a, l b or half rings . The separate parts l a, l b are identical and symmetric with respect to the axial plane of symmetry of the bearing, in order to reduce manufacturing costs . These two inner half rings l a, l b may advantageously be manufactured by cutting and stamping a metal sheet, the pieces obtained being then hardened by heat treatment. The bearing races intended for the rolling elements 3 may be ground and/or lapped in order to give them their geometric characteristics and their definitive surface finish. Since the two inner half-rings l a, l b are identical in this example, only one of them, having the reference "a" will be described here, it being understood that the identical elements of the other inner half-ring l b bear the reference "b" in the figures.

The inner half-ring l a o f the inner ring 1 comprises a first axial cylindrical portion 7a, a radial portion 8 a, a toroidal portion 9 a and a second axial cylindrical portion 10a. In the examp le illustrated, the first axial cylindrical portion 7a is an inner axial cylindrical portion 7a and the second axial cylindrical portion 10a is an outer axial cylindrical portion 10a, the inner axial cylindrical portion 7a being clo ser to the rotational axis X-X ' of the rolling bearing then the outer axial cylindrical portion 1 0a. The radial portion 8a is connected to the inner axial portion 7a by a rounded edge portion (not referenced) and to outer axial portion 10a by the toroidal portion 9a.

The toroidal portion 9a defines part of a raceway 1 1 a for the rolling elements 3. The radius of curvature of the raceway 1 1 a slightly exceeds the radius of the rolling elements 3 . The toroidal portion 9a extends axially towards the outside of the rolling bearing with the outer axial portion 10a. As illustrated, the inner axial portion 7a has an axial dimension less than the axial dimension of the outer axial portion 10a. The two inner half-rings l a, l b are arranged with the axially internal radial faces 12a, 12b of the radial portions 8a, 8b in axial contact with one another, substantially in the radial symmetry plane o f the ro lling elements 3.

The ro lling bearing may comprise an axial spacer (not shown) between the two separate inner parts l a, l b o f the inner ring 1 in order to adjust the axial clearance between the axially internal radial faces 12a, 12b o f the radial portions 8a, 8b.

In this embo diment, the outer ring 2 also comprises two separate parts 2a, 2b or half rings . The separate parts 2a, 2b are identical and symmetric with respect to the axial plane of symmetry o f the bearing, in order to reduce manufacturing costs. These two outer half rings 2a, 2b may advantageously be manufactured by cutting and stamping a metal sheet, the pieces obtained being then hardened by heat treatment. The bearing races intended for the rolling elements 3 may be ground and/or lapped in order to give them their geometric characteristics and their definitive surface finish. Since the two half- rings 2a, 2b are identical in this example, only one of them, having the reference "a" will be described here, it being understood that the identical elements of the other half-ring 2b bear the reference "b" in the figures.

The half-ring 2a o f the outer ring 2 comprises a first axial cylindrical portion 13 a, a radial portion 14a, a toroidal portion 15 a and a second axial cylindrical portion 16a. In the example illustrated, the first axial cylindrical portion 13 a is an outer axial cylindrical portion 13 a and the second axial cylindrical portion 16a is an inner axial cylindrical portion 16a, the inner axial cylindrical portion 16a being closer to the rotational axis X-X ' of the rolling bearing then the outer axial cylindrical portion 13 a. The radial portion 14a is connected to the outer axial portion 13 a by a rounded edge portion (not referenced) and to inner axial portion 16a by the toroidal portion 15 a. The toroidal portion 15 a defines part of a raceway 17a for the rolling elements 3.

The radius o f curvature o f the raceway 1 7a slightly exceeds the radius of the rolling elements 3. The toroidal portion 15 a extends axially towards the outside of the rolling bearing with the inner axial portion 16a. The two outer half-rings 2a, 2b are arranged with the axially internal radial faces 1 8 a, 1 8b of the radial portions 14a, 14b in axial contact with one another, substantially in the radial symmetry plane o f the rolling elements 3.

The ro lling bearing may further comprise an axial spacer (not shown) between the two separate outer parts 2a, 2b of the outer ring 2 in order to adjust the axial clearance between the axially internal radial faces 1 8a, 1 8b o f the radial portions 14a, 14b.

As an alternative, one of the rings 1 or 2 can be so lid and having on its outer cylindrical surface a toroidal groove, the radius of curvature of which is slightly greater than the radius of the rolling elements 3 and forms a bearing race for the rolling elements 3. The so lid ring may be manufactured by machining or by pressing a steel blank, which is then ground and optionally lapped at the bearing race in order to give the so lid ring its geometrical characteristics and its final surface finish.

The cage 4 comprises a plurality o f cavities 19 designed to house the rolling elements 3 and keep them uniformly circumferentially spaced. The cavities 19 are advantageously o f spherical shape with a diameter slightly greater than that of the rolling elements 3. The cavities 19 are provided in the radial thickness o f the cage 4 having a radial portion 20 radially facing the outer ring 2 and extending radially inwards by a conical portion 21 . The conical portion 2 1 is located radially facing the inner ring 1 and extends axially towards the rolling elements 3. The radial portion 20 and the conical portion 21 define the cavities 19. The conical portion 21 forms a guide portion for the rolling elements 3.

The annular housings 5 , 6, which are advantageously made of a stamped metal sheet, comprise each two annular distinct parts 22, 23 and 24, 25 respectively enclosing the two inner half-rings l a, l b and the two outer half-rings 2a, 2b so as to hold them firmly together in the axial direction. The distinct parts 22, 23 , 24, 25 of the annular housings 5 , 6 may advantageously be produced in an economical way from a single metal sheet by cutting and pressing. Each distinct part 22, 23 , 24, 25 have an L-shaped structure.

The first part 22 of the first annular housing 5 comprises a first axial cylindrical portion 26 axially extending towards the inner axial cylindrical portion 7a of one part l a of the inner ring 1 and having substantially the same inner diameter. As illustrated, the first axial cylindrical portion 26 o f the first housing 5 is referred as an outer cylindrical portion 26 having an inner bore of substantially the same diameter of the bore of the inner axial cylindrical portions 7a, 7b o f the inner ring 1 . As illustrated, the radial face 22a of the outer axial cylindrical portion 26 of the first part 22 is in axial contact with the radial face 27a of the inner axial cylindrical portion 7a of one separate part l a of the inner ring 1 .

The first part 22 of the first annular housing 5 further comprises a radial flange 28 extending radially from the outer axial cylindrical portion 26 towards the immediate vicinity o f the outer cylindrical portion 10a o f the inner ring 1 .

The second part 23 o f the first annular housing 5 comprises a second axial cylindrical portion 29 for retaining radially said one ring 1 . As illustrated, the second axial cylindrical portion 29 of the first housing 5 is referred as an inner cylindrical portion 29 having an outer surface in radial contact with the inner bore of the outer axial cylindrical portion 26 of the first part 22 and with the two inner axial cylindrical portions 7a, 7b o f the inner ring 1 . The second part 23 comprises a radial flange 30 extending radially from the inner cylindrical portion 29 towards the immediate vicinity o f the outer cylindrical portion 1 0b o f the inner ring 1 .

The inner half-rings l a, l b are centred in the inner axial portion 29 of the second part 23 of the first housing 5 by radial contact between the inner surface of the inner axial portions 7a, 7b and the outer surface of said inner axial portion 29. The outer radial faces 3 1 a, 3 1 b which form the outer edges of the outer axial portions 10a, 10b are in contact with the radial flanges 28 , 30. The inner axial cylindrical portion 29 is fixed to the outer axial cylindrical portion 26 by means of welding, brazing or glue.

Each of the inner half-rings l a, l b defines, with the first housing 5 , an annular clo sed space 32a, 32b. More specifically, the first closed space 32a is delimited by the inner axial portion 7a, the radial portion 8 a, the toroidal portion 9a and the outer axial portion 10a, and, adj acent to these portions, the radial flange 28 and the outer axial portion 26 of the first part 22 of the first housing 5. The second closed space 32b is delimited by the inner axial portion 7b, the radial portion 8b, the toroidal portion 9b and the outer axial portion 10b, and, adj acent to these portions, the radial flange 30 and a part of the inner axial portion 29 of the second part 23 of the first housing 5.

As an alternative, a magnetic element (not shown) may be mounted inside one or both of the clo sed spaces 32a, 32b, at the vicinity o f the corresponding raceways 1 1 a, l i b . The magnetic element can be a permanent magnet mounted radially on the inner surface of the outer axial cylindrical portion 10a o f one half ring part l a and axially against the inner surface of the radial flange 28 of the first housing 5.

As another alternative, an electronic element (not shown) comprising, for examp le, a sensor fixed to the inner surface of the toroidal portion 9a and communication means for communicating the information o f the sensor towards the outside of the rolling bearing. The sensor can be, for example, a temperature sensor, a vibration sensor ...

As illustrated, the first part 24 of the second annular housing 6 comprises a first axial cylindrical portion 33 for retaining radially said outer rings 2a, 2b . As illustrated, the first axial cylindrical portion 33 of the second housing 6 is referred as an inner cylindrical portion 33 having an inner bore in radial contact with the outer surface of the outer axial cylindrical portions 13 a, 13b of the outer rings 2a, 2b . The inner axial cylindrical portion 33 surrounds the outer rings 2a, 2b and is in contact with the outer surface o f the axial portions 1 3 a, 13b of the outer rings 2a, 2b . The first part 24 further comprises a radial flange 34 extending radially from the inner axial cylindrical portion 33 towards the immediate vicinity o f the radial flange 28 of the first part 22 of the first housing 5 , so as to leave a clearance between the inner edge 34a o f the radial flange 34 o f the second housing 6 and the inner edge 28a o f the radial flange 28 of the first housing 5.

The second part 25 of the second annular housing 6 comprises a second axial cylindrical portion 35 surrounding the inner axial cylindrical portion 33 of the first part 24. As illustrated, the second axial cylindrical portion 35 is referred as an outer cylindrical portion 35 having an inner bore in radial contact with the outer surface of the inner axial cylindrical portion 33. The second part 25 further comprises a radial flange 36 extending radially from the outer cylindrical portion 35 towards the immediate vicinity o f the radial flange 30 of the second part 23 of the first housing 5 , so as to leave a clearance between the inner edge 36a of the radial flange 36 of the second housing 6 and the inner edge 30a of the radial flange 30 of the first housing 5.

The outer axial cylindrical portion 35 is fixed to the inner axial cylindrical portion 33 by means o f welding, brazing or glue.

The half-rings 2a, 2b are centred in the inner axial portion 33 of the first part 24 of the second housing 6 by contact between the axial portions 13 a, 13b and the bore of the said inner axial portion 33 . The outer radial faces 37a, 37b which form the outer edges o f the outer axial portions 13 a, 13b are respectively in contact with the radial flanges 34, 36 of the parts 24, 25 o f the second housing 6, thus axially clamping the two outer half-rings 2a, 2b together. The outer radial faces 38 a, 38b which form the outer edges of the inner axial portions 16a, 16b are also in contact with the radial flanges 34, 36.

As an alternative, an axial clearance (not shown) may be provided between the outer edges 38a, 38b o f the inner axial portions 16a, 16b and the radial flanges 36, 38 of the second housing 6.

Each of the outer half-rings 2a, 2b defines, with the second housing 6, an annular clo sed space 39a, 39b . More specifically, the closed space 39a is delimited by the outer axial portion 13 a, the radial portion 14a, the toroidal portion 15 a, and the inner axial portion 16a, and, adj acent to these portions, the radial flange 34 o f the first part 24 of the second housing 6. One of the two or both spaces 39a, 39b may act as a lubricant reservoir, the lubricant contained in these spaces 39a, 39b not being depicted in the figures. The lubricant used may be grease or oil. Alternatively, it could be possible to foresee in the two closed spaces 39a, 39b a cellular or porous annular element saturated with oil. The cellular or porous annular elements act as sponges and under the effect of vibrations are able to release the lubricant oil which then passes as before through the passage means described hereinabove. The cellular or porous annular elements can take up the who le o f the clo sed spaces 39a, 39b or only part thereof.

Lubricant can be packed into the space 39a which constitutes a first lubricant reservoir between the outer half-ring 2a and the inner ring 1 . Lubricant is also packed into the second space 39b and into the vo lume remaining between the inner 1 and outer 2 rings.

Each outer part 2a, 2b of the outer ring 2 comprises passage means for the lubricant contained in the clo sed spaces 39a, 39b . In the example illustrated in Figure 1 , these passage means comprise a plurality o f axial through-ho les 40a, 40b provided the thickness o f the radial portion 14a, 14b at least partially facing one another, so as to put the two closed spaces 39a, 39b into communication. This arrangement, which can be maintained by suitable positioning during assembly or by angular indexing means (not shown), provided on the two outer half-rings 2a, 2b, allows the two closed spaces 39a, 39b to intercommunicate. Each inner radial face 1 8a, 1 8b o f the corresponding radial portion 14a, 14b is provided with a radial groove 41 a, 41 b forming a radial passage or duct so that the inner end of the radial duct is in communication with the corresponding through-ho le 40a, 40b and its inner end is in communication with the toroidal race 17a, 17b so as to guide the lubricant directly onto the balls 3. In this example, it should be understood that the axial through-ho les 40a, 40b associated with a radial duct can easily not be lo cated facing one another. As an alternative, these passage means may be o f several types, for example, radial through-ho les (not shown) may be provided in the thickness of each inner axial portion 16a, 16b .

The only difference with the embodiment of Figure 2, in which identical elements bear the same references, is that an axial clearance 42 is located between the radial face 22a of the outer axial cylindrical portion 26 and the radial face 27a of the inner axial cylindrical portion 7a of the inner ring 1 , in order to avoid any regrinding operations . The axial clearance is comprised, for example, between 0,2mm and 5mm.

The only difference with the embodiment of Figure 3 , in which identical elements bear the same references, is that one of the two or both spaces 32a, 32b may act as a lubricant reservoir, the lubricant contained in these spaces 32a, 32b not being depicted in the figures . The lubricant used may be grease or oil. Alternatively, it could be possible to foresee in the two closed spaces 32a, 32b a cellular or porous annular element saturated with oil. The cellular or porous annular elements act as sponges and under the effect of vibrations are able to release the lubricant oil which then passes as before through the passage means described hereinabove . The cellular or porous annular elements can take up the whole of the closed spaces 32a, 32b or only part thereo f.

Lubricant can be packed into the space 32a which constitutes a first lubricant reservoir between the inner half-ring l a and the outer ring 2. Lubricant can also be packed into the second space 32b and into the vo lume remaining between the inner 1 and outer 2 rings. As illustrated in Figure 3 , each inner part l a, l b of the inner ring 1 comprises passage means allowing the lubricant contained in the closed spaces 32a, 32b to flow towards the rolling elements. These passage means comprise a plurality o f axial through-ho les 43 a, 43 b provided the thickness of the radial portion 8 a, 8b at least partially facing one another, so as to put the two closed spaces 32a, 32b into communication. This arrangement, which can be maintained by suitable positioning during assembly or by angular indexing means (not shown), provided on the two inner half-rings l a, l b, allows the two closed spaces 32a, 32b to intercommunicate. Each inner radial face 12a, 12b of the corresponding radial portion 8a, 8b is provided with a radial groove 44a, 44b forming a radial passage or duct so that the outer end of the radial duct 44a, 44b is in communication with the corresponding through-ho le 43 a, 42b and its inner end is in communication with the toroidal race 1 1 a, l i b so as to guide the lubricant directly onto the balls 3. In this example, it should be understood that the axial through-ho les 44a, 44b associated with a radial duct can easily not be lo cated facing one another. As an alternative, radial through-ho les (not shown) may be provided in the thickness of each outer axial portion 10a, 10b.

A magnetic element (not shown) may be mounted inside one or both of the closed spaces 32a, 32b, at the vicinity o f the corresponding raceways 1 1 a, l i b. The magnetic element can be a permanent magnet mounted radially on the inner surface of the outer axial cylindrical portion 10a of one half ring part l a and axially against the inner surface o f the radial flange 28 of the first housing 5. For example, one or both closed spaces 32b may act as a lubricant reservoir, and the other closed space 32a contains the magnetic element.

As another alternative, an electronic element (not shown) comprising, for examp le, a sensor fixed to the inner surface of the toroidal portion 9a and communication means for communicating the information o f the sensor towards the outside of the rolling bearing . The sensor can be, for example, a temperature sensor, a vibration sensor ... Only one o f the two closed spaces 32b may act as a lubricant reservoir, and the other closed space 32a contains the electronic element.

As an alternative, a pressure creating means (not shown) comprising a layer o f an expansible material can be disposed inside one or both of the closed spaces 32a, 32b, in order to push the lubricant contained in the clo sed space 32a towards the rolling elements 3. The layer is preferably disposed on a side o f the corresponding closed space 32a opposite to the passage means 43 a, so that the layer does not contact the raceways 1 1 a, l i b. The pressure creating means may also be disposed inside one or both clo sed spaces 39a, 39b o f the outer ring 2.

The specific features and characteristics mentioned for each o f the embodiments could be applied without major modification to the other embodiments . Moreover, although the present invention has been illustrated using single-row ball bearings, it will be understood that the invention can be applied without major modification to bearings using rolling elements that are not balls and/or that have several rows of rolling elements. Alternatively, only one of the rings could comprise two half rings and be surrounded by a housing having two distinct parts as described above, and one of the rings can be a solid ring not surrounded by an housing.

Thanks to the housing made of two L-shaped parts, the rolling bearing according to the invention is less sensitive to deformation o f the surface of the cylindrical portion of the housing, and therefore has a good radial stiffness. Furthermore, such a rolling bearing prevents so lid and liquid po llutants from entering inside the rolling bearing.

Finally, thanks to the specific structure of the first part of the first housing, the rolling bearing is lightened in weight and his radial dimensions are reduced.

Claims

1. Rolling bearing comprising an inner ring (1), an outer ring (2), at least one row of rolling elements (3) disposed between raceways (1 la, 1 lb, 17a, 17b) provided on the inner and outer rings (1, 2), and at least one annular housing (5) inside which at least one of the rings (1) is arranged, said one ring (1) comprising two separate parts (la, lb), each separate part (la, lb) having two radial surfaces (27a, 31a) oriented towards the outside, the housing (5) comprising two annular distinct parts (22, 23) for retaining the separate parts (la, lb) of said one ring (1), characterized in that a first part (22) of the housing (5) comprises a first axial cylindrical portion (26) axially extending towards a first radial surface (27a) of one separate part (la) of said one ring (1) and the second part (23) of the housing (5) comprises a second axial cylindrical portion (29) in radial contact with said separate part (la) and said first axial cylindrical portion (26) of the first part (22).

2. Rolling bearing according to Claim 1, in which the first axial cylindrical portion (26) of the first part (22) of the housing (5) is in axial contact with said first radial surface (27a) of one separate part (la) of said one ring (1).

3. Rolling bearing according to Claim 1 or 2, in which each annular distinct parts (22, 23) comprises an axial cylindrical portion (26, 29) and a radial flange (28, 30) extending radially from the axial cylindrical portion (26, 29) towards the other ring (2), each radial flange (28, 30) being in axial contact with a second radial surface (31a, 31b) of one separate part (la, lb) of said one ring (1), opposite to the first radial surface (27a) of said one ring (1) and defining with one of the separate parts (la, lb) of said one ring (1) a closed space (32a, 32b).

4. Rolling bearing according to Claim 5, in which at least one of said closed spaces (32a, 32b) is adapted to contain a lubricant and act as a lubricant reservoir.

5. Rolling bearing according to Claim 4 , comprising passage means (43 a, 43b, 44a, 44b) allowing the lubricant contained in the closed spaces (32a, 32b) to flow towards the rolling elements (3) .

6. Rolling bearing according to one of the preceding claims, in which each separate part ( l a, l b) of one ring ( 1 ) comprises at least one axial cylindrical portion (7a, 7b , 10a, 10b) extending axially from a central portion (8a, 8b, 9a, 9b) towards the outside, the axial cylindrical portion (7a, 7b, 10a, 10b) end defining a radial surface (27a, 3 1 a, 3 1 b) .

7. Rolling bearing according to one of the preceding claims, in which the central portion of each separate part ( l a, l b) of one ring ( 1 ) comprises a radial portion (8a, 8b), a toroidal portion (9a, 9b) defining the raceways ( 1 1 a, 1 l b) and a rounded edge portion.

8. Rolling bearing according to Claims 5 and 7, in which the passage means for the lubricant comprise axial ho les (43 a, 43b) provided in the thickness of the radial portion (8a, 8b) o f at least one of the two separate parts ( l a, l b) of said one ring ( 1 ) .

9. Rolling bearing according to one o f the preceding claims, in which the annular distinct parts (22 , 23) of the housing (5 ) have been manufactured by cutting and pressing a metal sheet.

10. Rolling bearing according to any one o f the preceding claims, comprising a second annular housing (6) surrounding the other ring (2) and said other ring (2) comprises two separate parts (2a, 2b) , the second housing (6) comprising two annular distinct parts (24, 25) for retaining the separate parts (2a, 2b) of said other ring (2), the first part (24) of the second housing (6) comprises a first axial cylindrical portion (33) in radial contact with said separate parts of said other ring (2) and the second part (25) of the second housing (6) comprises a second axial cylindrical portion (35) in radial contact with said first axial cylindrical portion (33) of the first part (24) of the second housing (6) .

1 1 . Rolling bearing according to Claim 10, in which the first part (24) of the second housing (6) comprises a radial flange (34) extending radially from the first axial cylindrical portion (33) towards said one ring (1) and defining with one of the separate parts (2a) of said other ring (2) a first closed space (39a) and the second part (25) of the second housing (6) comprises a radial flange (36) extending radially from the second axial cylindrical portion (35) towards said one ring (1) and defining with one of the separate parts (2b) of said other ring (2) a second closed space (39b).

12. Rolling bearing according to Claim 11, in which at least one of the closed spaces (39a, 39b) is adapted to contain a lubricant and act as a lubricant reservoir, and in which at least one of said separate parts (2a, 2b) of said other ring (2) comprises passage means (40a, 40b, 41a, 41b) for the lubricant contained in the closed space (39a, 39b) to flow towards the rolling elements (3).

13. Rolling bearing according to any one of the preceding claims, comprising fixing means for fixing together the annular distinct parts (22, 23, 24, 25) of each housing (5, 6).

14. Rolling bearing according to Claim 11, in which the fixing means comprise welds or brazing or glue.

15. Rolling bearing according to any one of the preceding claims, in which said one ring (1) is the inner ring and said other ring (2) is the outer ring.

16. Rolling bearing according to any one of the preceding claims, in which each separate part (la, lb, 2a, 2b) of at least one of the rings (1, 2) are heat treated.

17. Rolling bearing according to any one of the preceding claims, comprising an axial spacer in axial contact between the radial portions (8a, 8b, 18a, 18b) of the two separate parts (la, lb, 2a, 2b) of at least one of the rings (1, 2) having two separate parts (la, lb, 2a, 2b).