Lubricant Recirculation in the Rolling Bearing of a Turbo Machine

Abstract

A rolling bearing for an aircraft turbomachine, comprising an inner ring (3) defining a first raceway (112) and an outer ring (4) defining a second raceway (124), characterized in that the bearing has at least one loop circuit (21, 22) for forced recirculation of lubricant, this loop circuit comprising a first recirculation circuit (21) comprising at least one lubricant inlet (1200), which is arranged at the level of the second raceway (124) and is connected by at least one duct (120, 166) created in the outer ring (4) to at least one lubricant outlet (1661) discharging into a second recirculation circuit (22) of the loop circuits (21, 22), this second recirculation circuit (22) comprising at least one duct (152, 1134, 1136; 1135, 1136) created in the inner ring (3).

Description

Technical Field

[0001] The present invention relates to rolling bearings for turbomachines, in particular for aircraft, which bearings comprise a lubricant recirculation circuit.

Background Art

[0002] Devices such as gas generators used in auxiliary power units for aircraft, or other types of devices using small turbomachines typically have bearings for their rotating shafts provided with rolling elements that are lubricated. To ensure this lubrication, an external lubrication system is provided with various components such as pumps, distribution circuits, and valves and solenoid valves. This external lubrication system reduces the performance of the engine (especially with respect to specific output and reliability) and accounts for a significant portion of the overall cost of the engine.

[0003] The lubricant (oil or grease) used to lubricate this type of bearing is injected into the bearing and serves to lubricate the bearing for only a limited period. The lubricant tends to move and stay in areas called dead areas. This can be reused but is then reinjected into the lubrication system.

[0004] Equipping rolling bearings with a lubricant recirculation circuit has already been proposed. However, in practice, lubricant recirculation is unreliable and not optimal.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention provides a simple, effective and economical solution to this problem by means of a self-lubricating bearing, i.e. a bearing that does not necessarily require an external lubrication system.

Means for Solving the Problems

[0006] Accordingly, the present invention advantageously proposes a rolling bearing for turbomachines, in particular for aircraft, the bearing being An inner ring defining a first orbit having a first diameter, an outer ring defining a second orbit, a plurality of rolling elements disposed between the inner ring and the outer ring and configured to roll on the first orbit and the second orbit and comprising, the bearing having at least one loop circuit for forced recirculation of a lubricant, the loop circuit comprising a first recirculation circuit having at least one lubricant inlet, the at least one lubricant inlet being disposed at the level of the second orbit and connected to at least one lubricant outlet opening into a second recirculation circuit of the loop circuit by means of at least one duct made in the outer ring, the second recirculation circuit comprising at least one duct made in the inner ring.

[0007] In the bearing according to the invention, each lubricant inlet of the first recirculation circuit forms an orifice opening into the second orbit, and the rolling elements can roll over this orifice.

[0008] This configuration has the advantage of generating the recirculation of the lubricant by means of a pumping effect. This pumping effect is achieved by the fact that the circuit opens directly into at least one of the orbits. The rolling elements roll over the outlet of the circuit and force the lubricant in the orbit into the lubricant inlet or into each lubricant inlet. Thus, the recirculation of the lubricant is activated without the need for external pumping means such as a hydraulic pump. This makes it possible to reduce the number of components implemented for the lubrication of the bearing, and to reduce the operating costs (no need to supply energy to the external pumping means) and the manufacturing costs (reduction of the complexity of the assembly). The fact that it can be done without an external pump system also makes it possible to limit the mass of the turbomachine.

[0009] The present invention can effectively utilize centrifugal force. In the prior art self-lubricating bearings, the centrifugal force tends to blow the lubricant towards the dead areas of the non-rotating outer part of the bearing, and the lubricant remains trapped in these dead areas where it accumulates. The higher the rotational speed inside the bearing, the greater the centrifugal force. By creating a circuit that forms a loop for forced recirculation of the lubricant with at least one inlet in the outer part of the bearing, the dead areas where the lubricant accumulates are avoided.

[0010] The bearings according to the present invention can have one or more of the following characteristics, either alone or in combination with each other.

[0011] Each lubricant inlet of the first recirculation circuit forms an orifice that opens onto a second track.

[0012] At least one lubricant outlet of the first recirculation circuit is formed by a discharge orifice arranged at a distance from the axis of the bearing that is less than or equal to the first diameter of the first track.

[0013] The bearing further comprises a cage that intervenes between the rings and holds the rolling elements apart, the cage having at least one inner surface configured to slide on the outer surface of the inner ring, and at least one radially oriented duct of the second recirculation circuit opens from the outer surface facing the inner surface, and the inner surface has a diameter slightly larger than the diameter of the outer surface so that the lubricant coming from the radially oriented duct can open into the cavity of the cage housing.

[0014] The rolling elements, the outer surface of the inner ring, and the inner surface of the cage are cylindrical.

[0015] The first recirculation circuit comprises at least two lubricant inlets aligned along an axial direction parallel to the axis of the bearing.

[0016] The first recirculation circuit comprises a series of pairs of lubricant inlets arranged at the level of the second track and a series of pairs of ducts associated with said lubricant inlets, the pairs of ducts being evenly distributed around the axis of the bearing, each pair of ducts extending in a substantially same plane passing through this axis.

[0017] The first recirculation circuit comprises at least two ducts, the at least two ducts being created within the outer ring, perpendicular to said axis and extending on both sides of the median plane of the bearing passing substantially through the center of the bearing.

[0018] Each pair of ducts is symmetric with respect to the median plane, the median plane being perpendicular to said axis and passing substantially through the center of the bearing.

[0019] Each duct of the first recirculation circuit comprises a first portion which extends radially outwards from the lubricant inlet and is extended by a second portion which mainly proceeds towards the axis of the bearing, this second portion leading to a lubricant outlet opening onto the second recirculation circuit.

[0020] The lubricant outlet engages with a lubricant inlet manifold of the second recirculation circuit formed by an annular recess of the inner ring, said annular recess having a bottom opening into at least one duct of the second recirculation circuit.

[0021] The rolling elements are rollers, in particular cylindrical; this type of rolling element has the advantage of being able to be used in high-speed rotation and high-temperature ranges. They are particularly suitable for use in aircraft turbomachinery.

[0022] The bearing comprises a sealing ring system between the inner ring and the outer ring on both sides of said rolling elements.

[0023] The inner ring or at least one element rotatably integrated with the inner ring comprises annular ribs for guiding the lubricant by centrifuging towards said lubricant inlets, these annular ribs extending towards the outer ring on both sides of the rolling elements.

[0024] The invention also relates to a turbomachine, in particular for an aircraft, comprising at least one bearing comprising one or more of the above-mentioned features, in which the inner ring of the bearing is rotatably integral with a rotating shaft of the turbomachine, while the outer ring is attached to a stator part of the turbomachine.

[0025] Further features and advantages of the present invention will become apparent from the following detailed description, for an understanding of which reference should be made to the accompanying drawings. [Brief description of the drawings]

[0026]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

[0027] 1 shows a schematic cross-sectional view of a part of a recirculating bearing 1 arranged on a first side of a rotation axis A of the bearing 1. The bearing 1 is mounted on a shaft 2, for example.

[0028] Generally, in the following description, the terms "longitudinal" and "axial" refer to the orientation of structural elements extending in the direction of the axis of rotation A. The term "radial" refers to the orientation of structural elements extending in a direction perpendicular to the axis of rotation A.

[0029] Also, when the cross-section of the annular element is described, for example, reference is made only to the portion on one side of the rotational axis A of the bearing 1, and the other portion is obtained by mirroring with respect to the axis A in the plane of the drawing.

[0030] The bearing 1 includes an inner ring 3, an outer ring 4, and a plurality of rolling elements 13. The inner ring 3 and the outer ring 4 are intended to pivot relative to each other about the rotational axis A (FIGS. 1, 2A, and 3).

[0031] Here, the bearing 1 further includes a cage 14, two sealing ring systems 17 in the form of sealing rings here, and two mounting annular parts 18 (FIG. 1).

[0032] The inner ring 3 includes an intermediate ring 11 and two side rings 15.

[0033] The outer ring 4 includes an intermediate ring 12 and two side rings 16.

[0034] The intermediate rings 11 and 12, and the side rings 15, side ring 16, sealing ring 17, and mounting annular part 18 are generally annular, that is, they have a rotational shape about the rotational axis A (FIGS. 1 and 3).

[0035] Furthermore, the bearing 1 is symmetric with respect to a symmetry plane P1 or a median plane, that is, it is a mirror image with respect to the plane P1. In particular, the inner ring 3, the outer ring 4, each rolling element 13, and the cage 14 are provided symmetrically with respect to the plane P1 here (FIG. 1).

[0036] Here, the rolling element 13 is a roller, particularly a cylindrical one.

[0037] The cage 14 defines a plurality of housings 140 in which the respective rolling elements 13 are accommodated (FIGS. 1 and 4). The purpose of the cage 14 is to keep the rolling elements 13 separated.

[0038] The intermediate ring 11 has an intermediate section 110 and two side sections 111 (FIG. 1). The intermediate section 110 and the side sections 111 are each in the shape of a substantially annular shape as the lower part of the intermediate ring 11. The outer diameter of the intermediate section 110 is smaller than that of the side sections 111. The intermediate section 110 and the side sections 111 define an internal track or a first track 112 therebetween for the rolling elements 13 to move by rolling. Here, the first track 112 is defined by an axially directed cylindrical annular surface 1100 (FIGS. 1 and 4). Two radially directed flat surfaces 1110 arranged on both sides of the axially oriented portion 1100 serve as axial positioning (centering) stops for the rolling elements 13. The side surfaces of the rolling elements 13 can slidably abut against either of the two both surfaces 1110.

[0039] The duct 113 is arranged in the intermediate ring 11. More specifically, the duct 113 passes through the intermediate ring 11 so as to open here into three orifices 1131, 1132 and 1133 respectively. For simplicity, only the (first) duct 113 is mentioned here, and the second duct 113 symmetric with respect to the plane P1 has a similar configuration. Further, further similar ducts 113 are provided in the ring 11 at an angular distance from each other about the axis of rotation A.

[0040] The orifice 1131 is provided on the end face 114 of the intermediate ring 11 (Figs. 1 and 2A). Orifices 1132 are provided on the surfaces on both sides of the first track 112 (Figs. 1, 2A, and 4). More specifically, the orifices 1132 are provided here at the height of the edge of the annular surface 1100 so that the rolling elements 13 can roll thereon, as a result of which the lubricant present on the surface of the rolling elements and on the first track 112 is forced into the orifices 1132. Thus, the orifices 1132 form lubricant inlets. The orifice 1133 is a discharge orifice, i.e., it forms a lubricant outlet. The lubricant outlet 1133 is provided on the external cylindrical surface 1111 that externally bounds the side section 111 of the ring 11 (Figs. 1 and 2A). The duct 113 can be subdivided into sub - ducts 1134, 1135, and 1136 (Fig. 2A). The sub - ducts 1134 and 1135 are axially oriented. Here, the sub - duct 1136 is radially oriented. The sub - ducts 1134 and 1135 are aligned with each other. The sub - duct 1136 extends transversely to the sub - ducts 1134 and 1135. The sub - ducts 1134, 1135, and 1136 are in fluid communication with each other respectively from the orifices 1131, 1132, and 1133.

[0041] The intermediate ring 12 comprises a plurality of ducts 120, an internal annular surface 121, and an external annular surface 122 (Figs. 1 and 4). Here, the ducts 120 are radially oriented. Each duct 120 opens into the internal annular surface 121 through an internal orifice 1200 and into the external annular surface 122 through an external orifice 1201.

[0042] The intermediate ring 12 is here preferably axially bounded by two flat end faces 123.

[0043] The intermediate portion 124 of the inner annular surface 121 forms an external track or second raceway intended for the rolling elements 13 to contact and roll thereon. The orifices 1200 are provided in the second raceway 124 so that the rolling elements 13 can roll thereon, and as a result, lubricant is pushed into these orifices. Thus, the orifices 1200 form lubricant inlets. When the rolling elements 13 are rollers, the raceway 124 is cylindrical. Advantageously, each roller can have a very slightly domed shape on both sides of the cylindrical contact area of the roller on the second raceway 124. This domed shape allows the roller to locally have a diameter that is very slightly smaller than the diameter of the roller defined as the diameter of its cylindrical contact area. This cylindrical contact area can be symmetric with respect to the plane P1 and its length can be between one quarter and two thirds of the length of the roller.

[0044] Preferably, the orifices 1200 are provided on both sides of the cylindrical contact area on the second raceway 124, and as a result, the rollers do not contact or hardly contact the two annular portions of the second raceway 124 where the orifices 1200 are provided. In fact, the very slightly domed shape of the rollers is provided so that there is no contact or very limited contact pressure between the rollers and the edges of the orifices 1200. This avoids, for example, generating the onset of corrosion at the level of the orifices 1200, which can occur in the case of high contact pressure due to the high local stresses developing at the level of the orifices 1200.

[0045] Therefore, when the rolling elements 13 are rollers, the fact that these rolling elements can roll on the orifice 1200 does not necessarily mean contact between the rolling elements and the two annular portions of the second track 124 on which the orifice is provided. Nevertheless, in all cases, the passage of the rollers over the orifice takes place at the level of the orifice with contact or quasi-contact between the rollers and the track 124, and as a result, the oil pumping effect provided is not significantly affected by the absence (quasi-contact) of possible contact.

[0046] Elements 15 to 18 are identical in pairs. Each of the elements 15 to 18 of the pairs of elements 15 to 18 is arranged symmetrically with respect to the other of the elements 15 to 18 with respect to a plane P1 transverse to the axis of rotation A (Figure 1).

[0047] The side ring 15 has an inner part 150 and an outer part 151 that are integral in rotation. Both the inner part 150 and the outer part 151 are substantially annular. The duct 152 is formed by a passage passing through the joint between the inner part 150 and the outer part 151. Here, the duct 152 is oriented axially close, preferably at an inclination of less than 20° with respect to the axial direction, for example, so that the centrifugal separation of the lubricant passing through the duct 152 forces the flow of the lubricant to the duct 113 passing through the intermediate ring 11. The inner part 150 and the outer part 151 are here integrated with each other (Figs. 1 and 2A) and can be advantageously achieved by additive manufacturing, in particular, to form the duct 152 that can have complex curves. The outer part comprises two annular ribs 155 and 156 in the form of annular ribs. Seen in cross-section, the annular rib 155 here extends obliquely away from the inner part 150, that is, forms a nose that moves away from the inner part 150 both in the radial outer direction and in the axial direction. As will be described later, the annular rib 155 is intended to provide guidance for the centrifugal lubricant. Seen in cross-section, the other annular rib 156 here forms a nose that extends axially substantially parallel to the inner part 150. The annular ribs 155 and 156 extend substantially axially opposite to each other. A first annular recess 157 in fluid communication with the duct 152 is defined between the annular rib 156 and the inner part 150. This first annular recess 157 forms the lubricant inlet manifold of the second recirculation circuit 22. A second annular recess 158 in fluid communication with the duct 152 is defined between the annular rib 155 and the inner part 150. The second annular recess 158 opens here to the end face 153, here a flat surface, through an orifice 154 that is here an annular opening.

[0048] The side ring 16 of the outer ring 4 is the outermost element in the radial direction of the bearing 1 (Fig. 1).

[0049] Each side ring 16 includes an axial segment 160 and a radial segment 161 (Figs. 1 and 2B). The axial segment 160 and the radial segment 161 are substantially L-shaped with respect to each other, and the radial segment 161 extends radially inward from the axial segment 160. However, the annular rim 162 extends axially in the same direction as the axial segment 160 from the radial segment 161.

[0050] The side ring 16 includes an annular surface 164 that bounds the axial segment 160 inwardly and a radial surface 163 that crosses the annular surface 164. The surfaces 163 and 164 define an annular space 165 that is intended to accommodate the intermediate ring 12 (Fig. 2B). And the surfaces 163 and 164 of the side ring 16 form stops for the surfaces 123 and 122 of the intermediate ring 12 (Fig. 1).

[0051] Each side ring 16 includes a plurality of ducts 166. Each duct 166 opens to the surface 164 through an inlet orifice 1660 (Fig. 2B). The ducts 166 extend from the inlet orifice 1660 through the respective side ring 16, more specifically through the axial segment 160, the radial segment 161, and then through the annular rim 162 to the discharge orifice 1661.

[0052] In addition, each side ring 16 has an annular space 168 that is defined radially and internally by the annular rim 162 and axially bounded by the radial segment 161. Each annular space 168 is intended to accommodate the annular rib 156 of the corresponding side ring 15 (Fig. 1).

[0053] The cavity 20 is defined among the intermediate ring 11, the intermediate ring 12, the side ring 15, the side ring 16, and the sealing ring 17 (Fig. 1). The cavity 20 forms a closed fluid-sealed volume in which the assembly formed by the rolling elements 13 and the cage 14 is accommodated within the lubricant sump 19.

[0054] In bearing 1, the sealing ring is received between the shoulder 169 of ring 16 and the inner part 150 of ring 15 and at least partially radially with respect to the radial segment 161 (Figs. 1 and 3). The sealing ring 17 seals the cavity 20 and keeps the lubricant 19 contained therein. Thus, the bearing 1 is lubricated in a closed circuit.

[0055] On side ring 16, the throat portion 167 opens in the direction of the axis of rotation A and is intended to receive the mounting annular portion 18 (Figs. 1, 2B and 3). And the mounting annular portion 18 functions to hold the sealing ring 17 on the side ring 16.

[0056] Here, the mutual relationship of the above elements and the operation of the bearing will be described in more detail.

[0057] In the illustrated embodiment (Fig. 1) where the bearing 1 is attached to the shaft 2, the inner ring 3 forms a movable assembly while the outer ring 4 forms a fixed assembly that is attached, non - limitingly, for example, to a fixed reference member (not shown) of an aircraft.

[0058] The rolling elements 13 are radially sandwiched between the intermediate ring 11 of the inner ring 3 and the intermediate ring 12 of the outer ring 4 (Figs. 1 and 3). And the rolling elements 13 are configured to contact and roll on the first track 112 and the second track 124. Thus, the track 124 is cylindrical, and as a result, the rolling elements 13, which are rollers here, can roll on it without losing contact at least at the level of the cylindrical contact area of the rollers on the second track 124.

[0059] In bearing 1, the intermediate ring 11 is axially sandwiched between two side rings 15 (Figs. 1 and 3).

[0060] And the annular rib 155 extends toward the middle ring 12 and the rolling elements 13. Specifically, the annular rib 155 has an inclined surface 1550 (FIG. 2A). The inclined surface 1550 faces the rolling elements 13 and extends radially outward and axially toward the lubricant inlet 1200 (FIG. 3). The inclined surface 1550 helps guide the lubricant 19 during rotation of the bearing 1 and thus acts as a support for centrifugal separation of the lubricant 19. Further, the annular rib 155 is configured to limit the volume of the cavity 20 and thus avoid the presence of dead areas where the lubricant 19 accumulates.

[0061] As described above, the middle ring 12 is received in the space 165 defined by the side ring 16.

[0062] In addition, the side ring 16 is arranged such that the annular ribs 156 of the side ring 15 are respectively rotatably received within the annular space 168.

[0063] The two sealing rings 17 are respectively arranged at the axial ends of the bearing 1 between the side ring 16 of the outer ring 4 and the movable side ring 15 (FIG. 3).

[0064] And the mounting annular portion 18 holds the sealing ring in a predetermined position and can thus ensure that the bearing 1 is sealed.

[0065] In this configuration, the above-described ducts are arranged together as follows (see FIG. 1).

[0066] - The duct 120 of the middle ring 12 is in fluid communication with the duct 166 of the side ring 16. In other words, the orifice 1201 is joined to the orifice 1660.

[0067] - The duct 166 is in fluid communication with the duct 152 of the inner ring 15. In other words, here, the duct 166 opens into the annular recess 157 from the annular rim 162 through the orifice 1661.

[0068] - The first annular recess 157, the duct 152, and the second annular recess 158 are in fluid communication as described above.

[0069] - The duct 152 is in fluid communication with the sub - ducts 1134, 1135, and 1136 of the intermediate ring 11. In other words, the second annular recess 158 is joined to the orifice 1131 (FIG. 2A).

[0070] When the shaft 2 is rotated, the intermediate ring 11 integrally attached thereto adopts the same rotational movement, that is, it rotates about the axis A with the same angular velocity as the shaft 2. Thus, the rolling elements 13 move by rolling on the first track 112 and the second track 124. At this time, the inner cylindrical surface 141 of the cage 14 slides on the outer cylindrical surface 1111 of the inner ring 3 (FIG. 2A). Each of the rolling elements 13 rolls about its own axis of rotation (not shown) parallel to the axis of rotation A when the rolling element is a cylindrical roller, and at the same time follows the annular stroke around the intermediate ring 11.

[0071] During this annular stroke, the rolling elements 13 pass through the orifices 1200, or more precisely, roll around these orifices 1200, that is, they pass through the lubricant inlets (FIGS. 1, 3, and 4). Then, the rolling elements 13 restrain the lubricant 19 and push the lubricant into the duct 120 through the lubricant inlet 1200.

[0072] Similarly, the rolling elements 13 pass through the lubricant inlet 1132 of the intermediate ring 11. Then, the rolling elements 13 restrain the lubricant 19 and push the lubricant into the duct 113, more specifically, into the sub - duct 1135 through the lubricant inlet 1132.

[0073] Therefore, the rolling elements 13 passing through the lubricant inlets 1200 and 1132 have the effect of creating a pumping effect. This pumping effect utilizes the kinematics of the rolling elements 13 to drive the lubricant 19 in a self - circulating dynamics, enabling the lubrication of the components of the bearing 1 as long as the rotation of the inner ring 3 continues. This phenomenon occurs both on the intermediate ring 11 due to the lubricant inlet 1132 positioned at the bottom of the first track 112 and on the intermediate ring 12 due to the lubricant inlet 1200 perforated around the movable assembly 3.

[0074] The above - mentioned pumping effect generates the lubricant flows F1 and F2.

[0075] The first lubricant flow F1 is generated by the rolling elements 13 passing through the lubricant inlet 1200 (FIGS. 1 and 2A). The flow F1 continuously flows through the ducts 120, 166, the recess 157, the duct 152, the recess 158, and the sub - duct 1134 (FIG. 1).

[0076] The second lubricant flow F2 is generated by the rolling elements 13 passing through the lubricant inlet 1132. The flow F2 flows through the sub - duct 1135.

[0077] The ducts 120, 166, the recess 157, the pipe 152, the recess 158, and the secondary duct 1134, together with the secondary duct 1136, thus belong to the first lubricant recirculation circuit 21 (FIG. 2A). Here, the first recirculation circuit more specifically comprises a series of pairs of ducts 120, 166, 152, 1134, 1136 that are regularly distributed around the axis A of the bearing and substantially extend in the same plane P2 passing through the axis A (FIG. 3). The first ducts 120, 166, 152, 1134, 1136 extend from a first lubricant inlet 1200 arranged on the second track 124, as shown herein, close to the first track 112 or, alternatively not shown, on this first track 112, to a first lubricant outlet 1133 arranged thereon. The second ducts 120, 166, 152, 1134, 1136, which are symmetrical to the first ducts described above with respect to the plane P1, extend from a second lubricant inlet 1200 arranged on the second track 124, as shown herein, close to the first track 112 or, alternatively not shown, close to this first track 112, to a second lubricant outlet 1133 arranged thereon.

[0078] The secondary duct 1135 and the secondary duct 1136 form the second lubricant recirculation circuit 22 (FIG. 2A).

[0079] The flows F1 and F2 merge into a common flow F3 of lubricant at the junction of the secondary ducts 1134 and 1135. The flow F3 flows radially outward within the intermediate ring 11 of the inner ring 3. Then, the flow F3 opens into the cavity 20 through the lubricant outlet 1133 and then directly lubricates the cage 14. The generation of the flows F1 and F2 creates a self - sufficient demand for lubricant at the levels of the tracks 112 and 124, and the lubricant recirculation cycle continues by itself. Thus, the recirculation circuits 21 and 22 are self - supplied when the bearing 1 is rotated.

[0080] The recirculation circuits 21 and 22 are provided on both the intermediate rings 11 and 12 and the side rings 16 and 15.

[0081] Therefore, the recirculation circuits 21 and 22 form a loop circuit for forced recirculation of the lubricant.

[0082] Preferably, the side ring 16 and / or the side ring 15 and / or the intermediate ring 11 are manufactured by additive manufacturing. In particular, this makes it possible to manufacture the recirculation circuits 21 and 22, which are very complex due to their plurality of curved ducts but without great difficulty.

[0083] The bearing 1 described above is intended in particular for implementation in the aviation field such as gas turbines (turbomachines, thrusters, auxiliary power units).

[0084] The lubricant 19 liquefies more or less under the influence of temperature, and this low-viscosity state makes it possible to initiate the pumping effect and thus activate the recirculation of the lubricant through the bearing 1.

[0085] The lubricant 19 can be grease or a liquid lubricant which can be oil. Preferably, the selected lubricant 19 is a high heat-resistant grease.

[0086] In an alternative embodiment not shown, the rolling elements 13 may be balls or tapered rollers instead of cylindrical rollers. In the case of balls, the surface of the second track 124 is configured to contact these spherical elements. Thus, the second track has an arcuate cross-section. Alternatively or cumulatively, in the case of balls, the surface of the first track 112 may be configured similarly and have an arcuate cross-section.

Claims

**Claim 1** An internal ring (3) defining a first raceway (112) having a first diameter (D1), an external ring (4) defining a second raceway (124), a plurality of rolling elements (13) arranged between the internal ring (3) and the external ring (4) and configured to roll on the first raceway (112) and the second raceway (124), a rolling bearing for a turbomachine, comprising: the bearing having at least one loop circuit (21, 22) for forced recirculation of a lubricant, the loop circuit comprising a first recirculation circuit (21) having at least one lubricant inlet (1200), the at least one lubricant inlet being arranged at the level of the second raceway (124) and connected to at least one lubricant outlet (1661) opening into a second recirculation circuit (22) of the loop circuit (21, 22) by means of at least one duct (120, 166) made in the external ring (4), the second recirculation circuit (22) comprising at least one duct (152, 1134, 1136; 1135, 1136) made in the internal ring (3), each lubricant inlet (1200) of the first recirculation circuit (21) forms an orifice opening onto the second raceway (124), and the rolling elements (13) are capable of rolling on this orifice, characterized in that it is a rolling bearing. **Claim 2** The bearing according to claim 1, wherein at least one lubricant outlet of the first recirculation circuit (21) is formed by a discharge orifice (1661) arranged at a distance from the axis (A) of the bearing that is less than or equal to the first diameter (D1) of the first raceway (112). **Claim 3** further comprising a cage (14) interposed between the rings (3; 4) and holding the rolling elements (13) apart, the cage (14) having at least one inner face (141) configured to slide on the outer face (1111) of the internal ring (3), at least one radially oriented duct (1136) of the second recirculation circuit (22) opening from the outer face (1111) facing the inner face (141), the inner face (141) having a diameter slightly larger than the diameter of the outer face (1111) such that lubricant coming from the radially oriented duct (1136) can open into the cavity (20) of the housing of the cage (14), the bearing according to claim 1 or 2. **Claim 4** The bearing according to claim 3, wherein the rolling elements (13), the outer surface (1111) of the inner ring (3), and the inner surface (141) of the cage (14) are cylindrical.

5. The bearing according to any one of claims 1 to 4, wherein the first recirculation circuit (21) comprises at least two lubricant inlets (1200) aligned along an axial direction parallel to the axis (A) of the bearing.

6. The first recirculation circuit (21) comprises a series of pairs of lubricant inlets (1200) arranged at the level of the second track (124), and a series of pairs of ducts (120, 166) associated with the lubricant inlets (1200), the pairs of ducts (120, 166) being evenly distributed around the axis (A) of the bearing, and each pair of ducts (120, 166) extending in the same plane (P2) passing through this axis (A). The bearing according to any one of claims 1 to 5.

7. The first recirculation circuit (21) comprises at least two ducts (120, 166), the at least two ducts (120, 166) being formed within the outer ring (4), perpendicular to the axis (A) of the bearing, and extending on both sides of the median plane (P1) of the bearing passing through the center of the bearing. The bearing according to any one of claims 1 to 6.

8. The bearing according to claim 6 or 7, wherein each pair of ducts (120, 166) is symmetric with respect to the median plane (P1), the median plane (P1) being perpendicular to the axis (A) of the bearing and passing through the center of the bearing.

9. Each duct (120, 166) of the first recirculation circuit (21) comprises a first portion (120) which extends radially outwards from the lubricant inlet (1200) and is extended by a second portion (166) which mainly travels towards the axis (A) of the bearing, this second portion (166) leading to a lubricant outlet (1661) opening onto the second recirculation circuit (22). The bearing according to any one of claims 1 to 8.

10. The lubricant outlet (1661) engages a lubricant inlet manifold of the second recirculation circuit (22) formed by an annular recess (157) of the inner ring (3), the annular recess (157) being in fluid communication with at least one duct (152) of the second recirculation circuit (22). The bearing according to claim 9.

11. The bearing according to any one of claims 1 to 10, wherein the rolling elements (13) are rollers.

12. The bearing according to any one of claims 1 to 11, comprising a sealing ring system (17) between the inner ring (3) and the outer ring (4) on both sides of the rolling element (13).

13. The inner ring (3) or at least one element (151) rotatably integrated with the inner ring (3) acts as a support for centrifugal separation of the lubricant and comprises an annular rib (155) for guiding the lubricant towards the lubricant inlet (1200), the annular rib (155) extending towards the outer ring (4) on both sides of the rolling element (13). The bearing according to any one of claims 1 to 12.

14. A turbomachine comprising at least one bearing according to any one of claims 1 to 13, wherein the inner ring (3) of the bearing is rotatably integral with the rotating shaft of the turbomachine, while the outer ring (4) is attached to the stator part of the turbomachine.

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