Spacer for rolling bearing having at least a reinforcing beam

The spacer is adapted for a rolling bearing comprising an inner ring, an outer ring and at least one row of contact rollers disposed between raceways provided on the rings. The spacer comprises opposite first and second portions 11, 12 facing one another and at least a first lateral portion 13 extending transversally between the first and second portions and connected to the portions. The first and second portions and the first lateral portion delimit at least partly a pocket 14 laterally open on the side opposite to the lateral portion 13 and configured to receive at least a contact roller. The first and second portions each comprise an inner contact surface 11a, 12a with an end face of the roller. The spacer further comprises at least one reinforcing beam 16, 17 extending transversally between the first and second portions and connected to the portions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from European Patent Application No. EP13160802 filed Mar. 25, 2013.

FIELD OF THE INVENTION

The present invention relates to the field of rolling bearings, in particular rolling bearings having an inner ring, an outer ring, and one or more rows of contact rollers therebetween. The invention relates more particularly to the field of large-diameter rolling bearings, notably those used in a tunnel boring machine.

BACKGROUND OF THE INVENTION

A large-diameter rolling bearing comprises generally two concentric inner and outer rings, at least a row of contact rollers arranged between raceways provided on the rings, and a plurality of spacers disposed circumferentially between the rollers. Such rolling bearings are generally loaded, both axially and radially, often with a relatively strong load.

French patent FR 2 222 898 relates to apertured spacers for rolling bearing which, by being assembled together, form a cage for the rollers. Each apertured spacer is of a substantially rectangular shape and is provided with a recess retaining the associated roller introduced by force through one aperture, the width of the aperture being less than the diameter of the roller. A convex boss is located at a lower corner of the spacer whereas a concave recess having a complementary shape is located at an opposite lower corner. Adjacent spacers are interengaged by virtue of the engagement of the boss of each spacer in the recess of the adjacent spacer.

With such spacers, the number of contact rollers which can be introduced between the rings of the rolling bearing is strongly limited. This leads to a low load bearing capacity as well as a limited service life.

One aim of the present invention is to overcome these drawbacks.

SUMMARY OF THE INVENTION

It is a particular object of the present invention to provide a spacer adapted to increase the load bearing capacity of the associated rolling bearing.

It is a particular object of the present invention to provide a spacer which is simple to manufacture, economic and having a good reliability.

It is a further object of the present invention to provide a spacer having a good stiffness while guaranteeing low deformations during and after manufacturing.

In one embodiment, the spacer for rolling bearing comprising an inner ring, an outer ring and at least one row of contact rollers disposed between raceways provided on the rings, comprises opposite first and second portions facing one another and at least a first lateral portion extending transversally between the first and second portions and connected to the portions, the first and second portions and the first lateral portion delimiting at least partly a pocket laterally open on the side opposite to the lateral portion and configured to receive at least a contact roller. The first and second portions each comprise an inner contact surface with an end face of the roller. The spacer further comprises at least one reinforcing beam extending transversally between the first and second portions and connected to the portions.

In one preferred embodiment, the at least one reinforcing beam extends transversally between the inner contact surfaces of the first and second portions and is connected to the surfaces.

Advantageously, the at least one reinforcing beam may comprise an inner contact surface forming a bearing surface for an exterior rolling surface of the roller. In one embodiment, the inner contact surface has in cross-section a profile in the shape of an arc of circle with a radius R defined by:
0.5×D≦R≦0.57×D,

with D corresponding to the diameter of the roller.

In one embodiment, the at least reinforcing beam is disposed at a corner of the first and second portions.

Preferably, the at least one reinforcing beam extends longitudinal edges of the first and second portions.

In one embodiment, the spacer comprises a first reinforcing beam disposed on the side opposite to the first lateral portion. The first reinforcing beam may extend between lateral edges of the first and second portions which are located on the side opposite to the first lateral portion.

The spacer may further comprise a second reinforcing beam facing the first reinforcing beam, the reinforcing beams being disposed both on one side of the first and second portions. In one embodiment, the second reinforcing beam is connected to the first lateral portion.

The spacer may further comprise, on the side opposite to the first lateral portion, a retaining means extending from one of the first and second portions towards the other portion and having an inner surface forming a bearing surface for an exterior rolling surface of the roller.

In one embodiment, the retaining means comprises a hook.

In another embodiment, the retaining means comprises a second lateral portion facing the first lateral portion, the lateral portions delimiting together with the first and second portions the pocket. The first and second lateral portion may each comprise an inner contact surface forming a bearing surface for an exterior rolling surface of the roller.

Advantageously, the first reinforcing beam is connected to the second lateral portion. A free edge of the second lateral portion may define with one of the first and second portions an aperture in order to open laterally the pocket on the side opposite to the first lateral portion.

In one embodiment, the spacer comprises at least first and second reinforcing beams extending transversally between the first and second portions and connected to the portions. The reinforcing beams are disposed both on one side of the first and second portions. The first reinforcing beam is disposed on the side opposite to the first lateral portion and the second reinforcing beam faces the first reinforcing beam.

With such an arrangement, the mounting of the roller into the spacer may be made by a simple axial pushing movement. In the mounted position, the associated roller is axially maintained in one direction. Besides, the mounting of the spacer and its associated roller into the rolling bearing is easier since the roller is carried by the beams on one side of the spacer.

In another aspect of the invention, a rolling bearing comprises an inner ring, an outer ring, at least one row of contact rollers disposed between raceways provided on the rings, and a plurality of spacers as previously defined and disposed circumferentially between the rollers.

The rolling bearing as previously defined may be particularly useful as a bearing for a tunnel boring machine.

DETAILED DESCRIPTION OF THE INVENTION

The rolling bearing as illustrated on theFIG. 1is a large-diameter rolling bearing comprising an inner ring1and an outer ring2between which is housed one row of contact rollers3. The rolling bearing also comprises a plurality of spacers4disposed circumferentially between the rollers3to maintain their circumferential spacing. As will be described later, the spacers4each exhibit a good stiffness and are adapted to avoid high deformations during and after manufacturing.

The inner and outer rings1,2are concentric and extend axially along the bearing rotation axis (not shown) of the rolling bearing. The rings1,2are of the solid type. A “solid ring” is to be understood as a ring obtained by machining with removal of material (by machining, grinding) from metal tube stock, bar stock, rough forgings and/or rolled blanks.

The rollers3are identical with one another and each comprise an exterior rolling surface3aand opposite end transverse faces3b,3cdelimiting axially the rolling surface. In the illustrated example, the rolling surface3aof each roller has a cylindrical profile. Alternatively, the rolling surfaces may have a spherical profile or a logarithmic profile. In the illustrated example, the angle between the rotation axis3dof each roller and the bearing axis is equal to 90°. The rotation axis3dof each roller extends radially.

The inner ring1has a bore1aof cylindrical shape designed to be fixed to a chassis or to a structure of machine (not shown) and delimited by opposite radial lateral surfaces1b,1c. The inner ring1also comprises a stepped exterior cylindrical surface1donto which an annular radial raceway5is formed. The raceway5has in cross-section a straight internal profile in contact with the rolling surfaces3aof the rollers3. The raceway5is formed by the radial surface provided between a first axial surface6of small-diameter and a second axial surface7of large-diameter of the stepped exterior cylindrical surface1d. The axial surface6forms an annular guiding surface which may be in radial contact with the spacers4. The axial guiding surface6is straight, disposed perpendicular to the raceway5and connected to the edge of small-diameter of the raceway by an annular concave fillet. The guiding surface6extends axially from the edge and is connected to the radial surface1cof the inner ring. The guiding surface6and the raceway5of the inner ring delimit an annular groove.

The outer ring2comprises an outer cylindrical surface2adelimited by opposite radial lateral surfaces2b,2c. The outer ring2also comprises a stepped annular bore2dof cylindrical shape into which an annular radial raceway8is formed. The raceway8has in cross-section a straight internal profile in contact with the rolling surfaces3aof the rollers3. The raceway5of the inner ring and the raceway8of the outer ring axially face each other and are parallel. The raceway8is formed by the radial surface provided between a first axial surface9of small-diameter and a second axial surface10of large-diameter of the stepped bore2d. The axial surface10forms an annular guiding surface which may be in radial contact with the spacers4. The guiding surface10of the outer ring and the guiding surface6of the inner ring radially face each other and are parallel. The guiding surface10is straight, disposed perpendicular to the raceway8and connected to the edge of large-diameter of the raceway by an annular concave fillet. The guiding surface10extends axially from the edge and is connected to the radial surface2bof the outer ring. The guiding surface10and the raceway8of the outer ring delimit an annular groove.

The raceway5and the guiding surface6of the inner ring define together with the raceway8and the guiding surface10of the outer ring an annular space inside which the rollers3and the spacers4are disposed. Each roller3arranged between the raceways5,8is maintained by the associated spacer4which may bear against the guiding surfaces6,10and the raceways5,8.

The spacers4are identical with one another and each placed between two consecutive rollers3. Each spacer4is made in one part by molding a polymer material such as polyamide. Alternatively, the spacers4may be made from metal or bronze.

As shown onFIGS. 2 to 5, each spacer4comprises two parallel inner and outer portions11,12adapted to come into contact with the facing guiding surfaces and the raceways of the inner and outer rings, and a lateral portion13extending transversally between the opposite portions11,12and adapted to be located circumferentially between two adjacent rollers3. The lateral portion13is connected to a lateral edge of the inner portion11and to the opposite facing lateral edge of the outer portion12. The inner and outer portions11,12forming first and second portions and the lateral portion13each have a rectangular shape with similar length and thickness. The width of the portions11,12and13is slightly smaller than the radius of the roller3.

As shown onFIG. 1, the raceways5,8and the guiding surface6,10of the inner and outer rings each form a flank having a direct contact surface with the inner and outer parts11,12of each spacer to have a slight relative sliding between each spacer4and the rings1,2. In order to limit the induced friction torque of the spacers4, slight axial clearances are foreseen between each spacer and the raceways5,8of the rings and slight radial clearances are foreseen between each spacer and the guiding surface6,10.

Referring once again toFIGS. 2 to 5, the inner and outer portions11,12and the lateral portion13of each spacer have in cross-section the overall shape of a C and delimit a pocket14for receiving one roller3. The pocket14is laterally open on the side opposite to the lateral portion13between the inner and outer portions11,12. In the mounted position of the spacer4into the rolling bearing, the pocket14is delimited in the circumferential direction by the lateral portion13and is delimited in the radial direction by the inner and outer portions11,12. In this mounted position, the pocket14of one spacer4is circumferentially open towards the adjacent spacer4. The pocket14of each spacer4is open both axially in the two directions and circumferentially in one direction. The pocket14is open on three sides. With regard to the rotation axis3dof the associated roller3, the inner and outer portions11,12extend radially, the lateral portion13extends axially between the portions and the pocket14is radially open toward the outside. On the side opposite to the lateral portion13, an opening or aperture is delimited axially by the free lateral edges of the inner and outer portions11,12and extends axially between these portions in order to open laterally the pocket14.

The inner and outer portions11,12of each spacer have inner planar contact surfaces11a,12afacing each other and forming bearing surfaces for the end faces3b,3cof the associated roller. The gap between the planar contact surfaces11a,12ais substantially equal to the length of the roller3. The lateral portion13comprises an inner planar contact surface13aforming a bearing surface for the rolling surface3aof the associated roller.

The inner portion11of each spacer also comprises a planar outer surface11bopposite to the inner surface11aand two spaced guiding ribs (not referenced) provided on the outer surface. The guiding ribs protrude outwards relative to the outer surface11band extend transversally on the outer surface from one of the longitudinal edges of the inner portion11to the other edge. The opposite longitudinal edges delimit the inner and outer surfaces11a,11b. In the mounted position of the spacer4into the rolling bearing, the outer surface11bfaces the guiding surface6of the inner ring while remaining distant from the latter, and the guiding ribs may come into contact with the guiding surface. Since the inner and outer portions11,12of each spacer are similar in the illustrated example, only one of them is described here in detail.

The lateral portion13of each spacer comprises a planar outer surface13bopposite to the inner contact surface13aand two spaced guiding ribs (not referenced) provided on the outer surface. The guiding ribs protrude outwards relative to the outer surface13band extend transversally on the outer surface from one of the longitudinal edge of the lateral portion13to the other edge. The opposite longitudinal edges delimit the outer surface13b. In another embodiment, it may be possible to have a spacer deprived of ribs on the inner, outer and lateral portions11,12and13.

The spacer4further comprises a hook15which slightly protrudes inwards toward the inner portion11from the free edge of the outer portion12. The hook15is disposed on the outer portion12on the side opposite to the lateral portion13. The hook15is centered on the free edge of the outer portion12and remains distant from the longitudinal edges of the outer portion. The hook15comprises an inner planar contact surface forming a bearing surface for the rolling surface3aof the associated roller. The hook15is adapted to interfere with the roller3in order to avoid an escape from the open pocket14. The hook15forms a circumferential retaining means for the roller3.

The spacer4further comprises first and second reinforcing beams16,17extending transversally between the inner and outer portions11,12. The reinforcing beams16,17extend transversally between the planar contact surfaces11a,12aof the inner and outer portions and are connected to the surfaces. The reinforcing beams16,17are disposed both on one side of the portions11,12.

The first reinforcing beam16is disposed on the side opposite to the lateral portion13. The reinforcing beam16extends transversally between the free facing lateral edges of the inner and outer portions11,12which are located on the side opposite to the lateral portion13. The reinforcing beam16is connected to the lateral edges. The reinforcing beam16also extends transversally between the facing longitudinal edges of the inner and outer portions11,12and is connected to the edges. The reinforcing beam16extends both the free lateral edges of the inner and outer portions11,12and the longitudinal edges of the portions. The reinforcing beam16is disposed at a corner of the planar contact surfaces11a,12aof the inner and outer portions. The reinforcing beam16has a concave inner surface16adirected inward towards the pocket14and forming a bearing surface for the rolling surface3aof the roller.

The second reinforcing beam17faces the first reinforcing beam16and is connected to the lateral portion13. The reinforcing beam17protrudes from the planar contact surface13atowards the first reinforcing beam16. The reinforcing beam17extends transversally between the facing longitudinal edges of the inner and outer portions11,12and is connected to the edges. The reinforcing beam17is disposed at a corner of the planar contact surfaces11a,12aof the inner and outer portions. The reinforcing beam17has a concave inner surface17adirected inward towards the pocket14and forming a bearing surface for the rolling surface3aof the roller. The inner surface17aextends the planar contact surface13aof the lateral portion13. Each of the inner contact surfaces16a,17aof the reinforcing beams has in cross-section a profile in the shape of an arc of circle with a radius R defined by 0.5×D≦R≦0.57×D with D corresponding to the diameter of the roller, R and D being expressed in mm.

The reinforcing beams16,17extend from the contact surfaces11a,12aof the inner and outer portions and do not protrude outwards with regard to these portions. The reinforcing beams are spaced apart one form another along the facing longitudinal edges of the inner and outer portions11,12and delimit an opening or aperture into which the roller3protrudes. On one side of the spacer4, the reinforcing beams16,17and the inner and outer portions11,12form a rectangular frame inside which extends the rolling surface3aof the roller.

The use of the reinforcing beams16,17makes it possible to increase the mechanical strength of the spacer4. The stiffness of the spacer4is also increased by interposing, between the facing inner and outer portions11and12, rigidifying beams16,17. In the mounted position of the spacer4into the rolling bearing, the stiffness of the spacer is increased in the radial direction.

Besides, with the reinforcing members16,17acting as transversal crossbars connected to the inner and outer portions, the deformations of the inner and outer portions are limited. The reinforcement beams16,17limit the bending of one of the inner and outer portions11,12relative to the other. In fact, with a spacer deprived of such reinforcing beams16and17, during and after the manufacturing, the spacer is free to shrink or bend on itself and the inner and outer portions11,12may be deformed inwards one relative to the other. This phenomenon can be problematic in the use of such a spacer later on because it can be impossible to mount the associated roller or the spacer can squeeze the roller during operation.

Otherwise, with the spacer4comprising the reinforcing beams16and17, the mounting of the spacer and its associated roller3is easier since the roller is carried by the beams on one side of the spacer.

In the mounted position of the roller3inside the spacer4, the inner and outer portions11,12, the lateral portion13and the hook15, and the reinforcing beams16,17maintain the roller. In the mounted position of each spacer4into the rolling bearing, the inner and outer portions11,12maintain radially the roller3, and the lateral portion13and the hook15circumferentially maintain the roller3. The reinforcing beams16,17axially maintain the roller3in one direction.

In the mounted position of the spacers4into the rolling bearing, at least one of the guiding ribs of the lateral portion of each spacer4bears against the rolling surface3aof the roller3which is housed into the adjacent spacer4since the pocket of the spacer is laterally open towards the lateral portion13of the other spacer. There is a direct contact between the guiding rib(s) of the lateral portion of one spacer and the adjacent roller3supported by the successive spacer4in the circumferential direction. In the mounted position, there is only one lateral portion13disposed circumferentially between two successive rollers3. The pocket14of each spacer enables to reduce the circumferential space between two successive rollers3. Accordingly, the number of rollers3disposed between the inner and outer rings1and2may be increased. This leads to higher load bearing capacity of the rolling bearing as well as an increase of the service life.

In the second example illustrated onFIGS. 6 to 9, in which identical parts are given identical references, the spacer4is adapted to maintain a roller3having an increased length, for example equal to twice the length of the roller illustrated in the first example. Alternatively, a pair of two superposed rollers may be maintained by the spacer4. In this case, the two associated rollers are mounted axially in contact to one another with regard to their common rotation axis.

In this example, the spacer4further comprises a second lateral portion18extending transversally from the outer portion12towards the inner portion11and facing the first lateral portion13. The first and second lateral portions13,18are parallel to one another. The second lateral portion18extends from the edge of the outer portion12located on the side opposite to the first lateral portion13. The lateral portion18extends towards the inner portion11while remaining distant from the latter. The inner and outer portions11,12and the lateral portions13,18each have a rectangular shape with similar thickness. The width of the inner and outer portions11,12and the lateral portions13,18is slightly smaller than the radius of the roller3.

The inner and outer portions11,12and the opposite first and second lateral portions13,18delimit the pocket14. An opening or aperture19is defined between the second lateral portion18and the inner portion11. The pocket14is laterally open on the side opposite to the first lateral portion13between the inner portion11and the second lateral portion18. In the mounted position of the spacer4into the rolling bearing, the pocket14is delimited in the circumferential direction by the first and second lateral portions13,18. In this mounted position, the pocket14of one spacer4is circumferentially open towards the adjacent spacer4with the aperture19. The pocket14of each spacer4is open both axially in the two directions and circumferentially in one direction. The pocket14is open on three sides. With regard to the rotation axis3dof the roller3held into the pocket14of each spacer, the inner and outer portions11,12extend radially, the first and second lateral portions13,18and the reinforcing beams16,17extend axially between the portions, and the pocket14is radially open toward the outside. The aperture19is delimited axially by the inner portion11and the lateral portion18. A free end of the lateral portion18defines with the free edge of the inner portion11the aperture19to open laterally the pocket14on the side opposite to the first lateral portion13. The free edge of the second lateral portion18remains distant from the inner portion11to delimit the aperture19.

The second lateral portion18of the spacer comprises an inner planar contact surface18afacing the contact surface13aof the lateral portion13and forming a bearing surface for the rolling surface3aof the roller. In the case of the spacer4maintains two superimposed rollers, the lateral portion18may have a length greater than the length of the upper roller in order to extend beyond the zone of contact between the upper roller and the lower roller. Accordingly, the inner contact surface18aalso forms a bearing surface for the rolling surface of the lower roller.

In this example, the first reinforcing beam16comprises an extension20which protrudes from the longitudinal edge of the beam located on the side opposite the first lateral portion13and which is connected to the second lateral portion18. The extension20of the reinforcing beam has a length equal to the one of the lateral portion18and is connected to the planar contact surface12aof the outer portion. The extension20extends transversally between the free edge of the lateral portion18and the longitudinal edge of the outer portion12. The extension20faces the first reinforcing beam16. The extension20has a concave inner surface20aforming a bearing surface for the rolling surface3aof the roller which extends the concave inner surface16aand which is connected to the planar contact surface18aof the lateral portion18.

The general structure of each spacer4is lightened by the provision of a pocket14defined by three or four portions or lugs and open in the circumferential direction towards the outside on the side opposite to the lateral portion13. A weight reduction for each spacer4is thus obtained. Besides, with the reinforcing beams16,17extending between the inner and outer portions11and12, the mechanical strength and the stiffness of the spacer4are increased. The deformations of the portions of the spacer are also reduced during and after the manufacturing and during use.

In the disclosed examples, each spacer comprises two reinforcing struts or beams provided between the inner and outer portions11,12. Alternatively, it could be possible to foresee only one reinforcing beam, for instance the one disposed on the side opposite to the lateral portion13, or more than two reinforcing beams.

Although the invention has been illustrated on the basis of a rolling bearing having a single row of contact rollers, it should be understood that the invention can be applied to bearings having more rows of rollers. Otherwise, in the illustrated examples, the rolling bearing is adapted to accommodate axial loads. Alternatively, it may also be possible to have a rolling bearing adapted to accommodate radial loads or both axial and radial loads. Furthermore, the inner ring and/or the outer ring may comprise gearing teeth on their outer periphery, so as to be connected to driving gears for instance connected to the output shaft of a motor.