BEARING FOR AN AIRCRAFT TURBOMACHINE

Abstract

The invention relates to a rolling bearing (401) for an aircraft turbomachine comprising an inner ring and an outer ring (403) coaxial about an axis of rotation, and rolling elements and a cage separating the rolling elements, located between the inner ring and the outer ring (403). The outer ring (403) has at least one drainage channel (405) extending from an inner face (403ba) of said outer ring (403) to a downstream face (403bb) of said outer ring (403) and which has no edges or right angles between different portions of its extent. Figure for the abstract: Fig. 4

Description

Title of the invention: ROLLING BEARING FOR AN AIRCRAFT TURBO-MACHINE Technical field

[0001] The invention relates in particular to a rolling bearing for an aircraft turbomachine and an assembly comprising such a rolling bearing and means for supporting said rolling bearing. Prior art

[0002] It is known to use ball bearings to ensure the axial and radial positioning of shafts of aircraft turbomachines or other rotating machines, or to ensure the transmission of forces between a stator and a rotor while minimizing the moment along the axis of rotation (of the rolling bearing), as well as friction losses.

[0003] As illustrated in [Fig.l] and [Fig.2], a rolling bearing of this type, such as rolling bearing 101, is conventionally constituted by an inner (rolling) ring 103 which has a raceway, which can be divided into two half-rings, such as half-rings 103a and 103b in the example shown, which each carry a half-raceway and an outer ring 105 which has a raceway, and which can also be divided into two half-rings, such as half-rings 105a and 105b in the example shown, which each carry a half-raceway.

[0004] Furthermore, a rolling bearing of this type, such as the rolling bearing 101, also comprises balls, or more generally rolling elements 107, and a cage (not visible in the figure) separating the rolling elements which aims to ensure the correct circumferential distribution of the rolling elements in the rolling bearing.

[0005] In the particular case shown in [Fig.l] and [Fig.2], the half-tracks 105a and 105b of the outer ring 105 have non-tangent sections, but secant at the bottom of the groove, which thus form an ogival section. As a result, the balls do not come into contact with the bottom of the groove, which opens up the possibility of drilling drainage holes therein, thus forming a drainage conduit.

[0006] Such a drainage conduit makes it possible to limit the quantity of liquid lubricant (such as oil, for example) present in the groove, and to avoid the phenomena of mechanical losses due to churning and fluid friction which can become significant when the linear speed is high.

[0007] In certain uses of such a rolling bearing, the dynamics of the shaft guided by the bearing may require the use of bearing support means (such as support means 109) called “suspended” or “flexible”, that is to say which allow, by deformation of said support means, a translational movement of the immobile part in rotation of the bearing (i.e. of the external ring) in the plane orthogonal to the axis. In addition, such a suspension may or may not be accompanied by a damping device, for example of the squeeze-film type.

[0008] However, the known geometries of rolling bearings with an outer raceway in the shape of an ogive with a drainage duct as well as flexible bearing support means with a squeeze-film type damping device have poor compatibility.

[0009] Indeed, effective drainage at the bottom of the warhead requires not only good dimensioning of the holes, but also very low pressure losses in their extensions up to a recovery enclosure. In other words, the geometry of the drainage duct has a determining impact on whether or not the liquid lubricant experiences a pressure drop during its flow in said duct.

[0010] Furthermore, a damping system (such as a squeeze film) should preferably be axially centered on the median plane of the rolling bearing. However, as illustrated in [Fig. 3] in more detail, a simple radial drilling at the bottom of the ogive, connected to a groove on the outer surface of the outer ring (in this case the half-ring), results in the presence of a right angle in the flow path 301 of the liquid lubricant which in turn results in significant pressure losses.

[0011] Thus, in conclusion, the geometries existing or envisaged until now for the drainage conduits of rolling bearings, in particular associated with suspended support means and / or a damping system, result in pressure losses that are too great to obtain optimal drainage. Summary of the invention

[0012] The present invention provides a solution to these drawbacks.

[0013] Thus, one objective of the invention is to reduce the pressure losses associated with the flow of liquid lubricant in a drainage duct of a rolling bearing.

[0014] To this end, the invention according to a first aspect relates to a rolling bearing for an aircraft turbomachine, said rolling bearing comprising an inner ring and an outer ring coaxial along an axis of rotation, and rolling elements and a separating cage for the rolling elements, located between the inner ring and the outer ring,

[0015] said outer ring comprising at least one drainage conduit, configured to allow the flow of a liquid lubricant from the inside to the outside of said rolling bearing,

[0016] said rolling bearing being characterized in that said drainage duct extends from an internal face of said external ring to a downstream face of said external ring and does not has no edges and no right angles between different portions of its extent.

[0017] The rolling bearing according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0018] - the outer ring is made up of an upstream half-ring and a downstream half-ring and the drainage conduit extends from an inner face of said downstream half-ring to a downstream face of said downstream half-ring.

[0019] - the half-rings of the outer ring form, at the level of the inner face of said outer ring, a warhead-shaped section.

[0020] - the at least one drainage conduit comprises:

[0021] - an input, axially centered on a median plane of the rolling bearing;

[0022] - a first part, located at the level of an upstream face of the downstream half-ring;

[0023] - a second part, located at the level of an external face of the downstream half-ring; and,

[0024] - an outlet, located at an intersection of an external face and a downstream face of the downstream half-ring.

[0025] - the at least one drainage conduit has been machined in the outer ring.

[0026] - the outer ring was manufactured by additive manufacturing.

[0027] - the outer ring comprises a plurality of equally distributed drainage conduits ang- broadly according to its circumference.

[0028] The invention according to a second aspect also relates to an assembly comprising a rolling bearing according to the first aspect and support means configured to hold the outer ring and to allow, by deformation of said support means, a translation of said outer ring in a plane orthogonal to the axis of rotation.

[0029] The assembly according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0030] - the outer ring and the support means are configured to generate, from the liquid lubricant, a squeeze-film type damping system between said support means and said outer ring.

[0031] - the drainage conduit also extends into the support means, for example at the interface between the outer ring and said support means, with a portion of the section of said drainage conduit extending into the support means and another portion of the section of said drainage conduit extending into the outer ring.

[0032] The invention according to a third aspect finally relates to an aircraft turbomachine comprising an assembly according to the second aspect. Brief description of the drawings

[0033] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which:

[0034] [Fig.l] is a sectional view and a perspective view of an embodiment of a rolling bearing according to the state of the art;

[0035] [Fig.2] is a pair of sectional views of an embodiment of a rolling bearing according to the state of the art;

[0036] [Fig. 3] is a perspective view of an embodiment of support means and an outer ring of a rolling bearing according to the state of the art;

[0037] [Fig.4] is a set of perspective views of an embodiment of support means and an outer ring of a rolling bearing according to the invention;

[0038] [Fig.5] is a perspective view of an embodiment of an outer half-ring of a rolling bearing according to the invention; and,

[0039] [Fig.6] is a set of perspective views of an embodiment of an outer ring of a rolling bearing according to the invention. Description of the embodiments

[0040] With reference to [Fig.4] and [Fig.5], we will now describe an embodiment of a rolling bearing 401 for an aircraft turbomachine according to the invention. Such a rolling bearing can be used, for example, in an aircraft turbomachine to guide the rotation of a shaft while minimizing friction losses.

[0041] [Fig.4] and [Fig.5] show only certain elements of the rolling bearing 401, the other elements not shown are in accordance with the elements of a rolling bearing 101 according to the state of the art as shown in [Fig.1] and [Fig.2].

[0042] Generally, the rolling bearing 401 comprises an inner ring and an outer ring 403 which are coaxial along a rotation axis X. Furthermore, in the non-limiting example shown, the outer ring 403 is made up of a first half-ring 403a and a second half-ring 403b. The first half-ring is called the upstream half-ring and the second half-ring is called the downstream half-ring. The terms “upstream” and “downstream” refer to the direction in which a liquid lubricant of the rolling bearing (described later) tends to flow when said rolling bearing is mounted and used in an aircraft turbomachine. Furthermore, those skilled in the art will appreciate that, depending on the arrival of the liquid (lubricant) in a given enclosure, it is possible to direct its flow in one direction or the other.

[0043] In all cases, the inner and outer rings (whether or not made up of half-rings) form, at the level of the internal faces of the bearing (i.e. the face intended to be in contact with the rolling elements), tracks on which rolling elements can roll. Indeed, the rolling bearing 401 also comprises elements rolling elements and a separating cage of the rolling elements which are located between the inner ring and the outer ring 403 of the bearing. These rolling elements can be, for example, balls or rollers.

[0044] Furthermore, in the particular embodiment shown in [Fig.4] and [Fig.5], the half-rings 403a and 403b of the outer ring 403 form, at the level of the inner face of the outer ring 403, a cross-section in the shape of an ogive.

[0045] The axis of rotation X is the axis at which an element is intended to be positioned, such as for example a shaft of an aircraft turbomachine, the rotation of which must be guided by the rolling bearing 401.

[0046] The terms "internal" and "external", in relation to the rings, respectively designate the ring of smaller diameter intended to be in contact with the rotating element and the ring of larger diameter intended to be kept stationary in rotation (for example by support means such as those described below).

[0047] Furthermore, in the following, the terms "inner" and "outer", relative to the rolling bearing, respectively designate, on the one hand, what is located, in the volume of the rolling bearing, between the inner ring and the outer ring and, on the other hand, what is located outside the volume of the rolling bearing.

[0048] As can be seen in [Fig.4] and [Fig.5], the outer ring 403 comprises at least one drainage duct 405, configured to allow the flow of liquid lubricant (for example, oil) from the inside to the outside of the rolling bearing 401. More precisely, in the non-limiting example shown, the drainage duct 405 extends from an inner face 403ba of the downstream half-ring 403b to a downstream face 403bb of the downstream half-ring 403b.

[0049] More precisely still, in the non-limiting example shown, the drainage duct comprises an inlet 405a which is axially centered on a median plane (plane of symmetry of the bearing orthogonal to the axis of rotation X) of the rolling bearing 401, a first part 405b which is located at an upstream face of the downstream half-ring 403b, a second part 405c which is located at an external face of the downstream half-ring 403b and finally an outlet 405d which is located at an intersection of the external face and a downstream face of the downstream half-ring 403b.

[0050] In all cases, generally, the drainage conduit 405 extends from an internal face of the external ring 403 to a downstream face of the external ring 403. Furthermore, the drainage conduit 405 has no edges and no right angles between different portions of its extent.

[0051] In other words, over the entire extent of the drainage conduit 405, the latter does not include an intersection between two flat surfaces and also does not include two sections (i.e. two portions) which are perpendicular to each other.

[0052] Thus, advantageously, the geometry of the drainage conduit 405 makes it possible to minimize pressure losses, i.e. pressure drops of the liquid lubricant during its flow in the drainage pipe.

[0053] Generally speaking, a person skilled in the art will know how to adapt the geometry of the drainage duct, such as for example the angles formed between different portions of the duct and / or relative to the rolling track, and / or relative to the axis of rotation, as well as the different fillets and roundings present in the drainage duct so as to minimize the pressure losses associated with said drainage duct.

[0054] Furthermore, in the non-limiting example shown, the outer ring 403 actually comprises a plurality of drainage ducts 405 which are equally distributed angularly along its circumference. In other words, a plurality of drainage ducts 405 is distributed over the 360 ​​degrees of the circumference of the outer ring 403 with an identical angle between each drainage duct 405. Advantageously, liquid lubricant is thus extracted from the interior of the rolling bearing in several locations in a homogeneous manner (insofar as the ducts are identical in this non-limiting example).

[0055] In the particular embodiment described with reference to [Fig.4] and [Fig.5], the at least one drainage conduit has been machined in the outer ring. The conduit can thus be obtained in a simple manner from a ring according to the state of the art. However, the geometry of said conduit is limited by this technique used to create it.

[0056] [Fig. 6] thus illustrates another embodiment of a rolling bearing according to the invention in which the outer ring has been manufactured by additive manufacturing. Advantageously, the geometries that can be produced for the drainage duct are more varied. In the non-limiting example shown in [Fig. 6], the drainage duct follows the path of a smooth curve in which the duct changes inclination very gradually from its inlet to its outlet. The flow of the liquid lubricant in the duct can therefore be optimized by choosing an optimal geometry and the pressure losses resulting from this flow can be considerably reduced.

[0057] As can be seen again in [Fig. 4], the rolling bearing 401 can also be included in an assembly 407 which also integrates support means which are configured to hold the outer ring 403. In particular, the support means 409 shown in [Fig. 4] are means which allow the suspension of the rolling bearing 401, that is to say the translation of the outer ring 403 in a plane orthogonal to the axis of rotation X. More precisely, it is the deformation of the support means 409, in particular made possible by the U-shape of said means, which allows this translation and therefore the suspension of the rolling bearing.

[0058] Furthermore, in a particular embodiment of such an assembly, the outer ring 403 and the support means 409 may be configured to generate, from the liquid lubricant, a squeeze-film type damping system (i.e. a thin layer of liquid acting as a shock absorber) between the support means and said outer ring.

[0059] In yet another embodiment, the drainage conduit may also extend into the support means 409, for example at the interface between the outer ring 403 and the support means 409, with a portion of the section of the drainage conduit 405 extending into the support means 409 and another portion of the section of the drainage conduit 405 extending into the outer ring 403.

[0060] In such a configuration, the pressure losses of the liquid lubricant, typically linked to the additional difficulty of flow of the liquid at the interface between the rolling bearing and its support means, can also be reduced due to the introduction of a drainage conduit whose shape is not limited by this interface.

Claims

Claims

1. Rolling bearing (401) for an aircraft turbomachine, said rolling bearing (401) comprising an inner ring (103) and an outer ring (403) coaxial along a rotation axis (X), and rolling elements (107) and a separating cage for the rolling elements (107), located between the inner ring (103) and the outer ring (403), said outer ring (403) comprising at least one drainage duct (405), configured to allow the flow of a liquid lubricant from the inside to the outside of said rolling bearing (401), said rolling bearing (401) being characterized in that said drainage duct (405) extends from an inner face of said outer ring (403) to a downstream face of said outer ring (403) and has no edges and no right angles between different portions of its extent.

2. A rolling bearing (401) according to claim 1, wherein the outer ring (403) consists of an upstream half-ring (403a) and a downstream half-ring (403b) and the drainage conduit (405) extends from an inner face (403ba) of said downstream half-ring (403b) to a downstream face (403bb) of said downstream half-ring (403b).

3. Rolling bearing (401) according to claim 2, wherein the half-rings (403a, 403b) of the outer ring (403) form, at the internal face of said outer ring, a ogive-shaped section.

4. Rolling bearing (401) according to claim 3, wherein the at least one drainage duct (405) comprises: - an inlet (405a), axially centered on a median plane of the rolling bearing (401); - a first part (405b), located at an upstream face of the downstream half-ring (403b); - a second part (405c), located at an external face of the downstream half-ring (403b); and, - an outlet (405d), located at an intersection of an external face and a downstream face of the downstream half-ring (403b).

5. A rolling bearing (401) according to any one of claims 1 to 4, wherein the at least one drainage conduit (405) has been machined into the outer ring.

6. A rolling bearing (401) according to any one of claims 1 to 4, wherein the outer ring (403) has been manufactured by additive manufacturing.

7. Rolling bearing (401) according to any one of claims 1 to 6, wherein the outer ring (403) comprises a plurality of drainage conduits (405) equally distributed angularly along its circumference.

8. Assembly (407) comprising a rolling bearing (401) according to any one of claims 1 to 7 and support means (409) configured to hold the outer ring (403) and to allow, by deformation of said support means (409), a translation of said outer ring (403) in a plane orthogonal to the axis of rotation (X).

9. An assembly (407) according to claim 8, wherein the outer ring (403) and the support means (409) are configured to generate, from the liquid lubricant, a squeeze film type damping system between said support means (409) and said outer ring (403).

10. An assembly (407) according to claim 8 or claim 9, wherein the drainage conduit (405) also extends into the support means (409), for example at the interface between the outer ring (403) and said support means (409), with a part of the section of said drainage conduit (405) extending into the support means (409) and another part of the section of said drainage conduit (405) extending into the outer ring (403).

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