DEVICE FOR DAMPING A ROLLING BEARING WITH A RIGID BEAM GUIDED BY A FLEXIBLE CAGE

Description

Technical field

[0001] The invention relates to the field of rolling bearings for guiding the rotation of a shaft such as an aircraft turbomachine shaft.

[0002] The invention relates in particular to the field of rolling bearings with damping by compressed fluid film. State of the prior art

[0003] Damping a bearing by a film of compressed fluid is a well-known technique in the field of turbomachinery and particularly in the aeronautical field. Document EP 2 538 036 B1 describes a rolling bearing equipped with such a damping device. With reference to the figure 2of this document, this device comprises a cage 44 and a rigid support 64 radially forming between them a fluid damping cavity 50 capable of forming a circumferential film of compressed fluid. The cage 44 comprises a ring 48 mounted on the outer ring 52 of the bearing as well as radially deformable columns 46 so as to allow radial displacement of the ring 48 and therefore of the bearing relative to the rigid support 64.

[0004] The damping devices known in the prior art are relatively bulky. For example, the damping device described in document EP 2 538 036 B1 has an axial dimension almost three times greater than the axial dimension of the bearing. Another example is described in document FR 2 951 232. Statement of the invention

[0005] The present invention aims to provide a damping device for a rolling bearing having both good damping performance and limited bulk, so as to allow its integration into a narrow space, for example within an internal drive housing of an accessory drive system of an aircraft propulsion assembly.

[0006] To this end, the invention relates to a device for damping a rolling bearing, this device comprising an annular support and a cage extending axially along an axis of revolution, this cage comprising: a fixing ring, a ring configured to be mounted on the periphery of the bearing or to form an outer ring of the bearing, columns connecting the ring to the fixing ring, these columns extending obliquely relative to said axis of revolution and being circumferentially spaced from each other so that, for each pair of circumferentially contiguous columns, these columns define between them an intercolumn opening.

[0007] The ring and the annular support radially form between them a fluid damping cavity capable of forming a circumferential film of compressed fluid.

[0008] According to the invention, the annular support comprises a plurality of teeth each extending radially through a respective inter-column opening of the cage. In addition, the annular support comprises a toothed ring and a fixing piece, the toothed ring carrying said teeth and delimiting said fluid damping cavity, the fixing piece being fixed to the toothed ring.

[0009] Such nesting of the cage and the annular support makes it possible to reduce the size of the damping device compared to the damping devices known in the prior art. Indeed, the invention makes it possible to arrange all the parts of the annular support in the free spaces of the cage, in this case the inter-column spaces, so that the annular support has axial and / or radial dimensions identical to or smaller than the axial and / or radial dimensions of the cage, the axial dimension of the cage and in particular of the ring being able to be substantially identical to that of the bearing.

[0010] In this document, the term "oblique" means an orientation that is non-parallel and non-perpendicular to a reference direction or axis. Thus, the columns extend both axially and radially relative to said axis of revolution.

[0011] Preferably, each column of the cage may comprise a first end connected to a first axial end of the ring and a second end connected to the fixing ring and located axially in line with a second axial end of the ring.

[0012] In one embodiment, the attachment part of the annular support may bear against the attachment ring of the cage.

[0013] This allows the cage and the annular support to be connected to a frame using common fixing means and, moreover, to reduce the radial size of the device.

[0014] In one embodiment, the attachment part of the annular support may comprise tabs each bearing against a respective tooth of the toothed crown.

[0015] In one embodiment, the ring may comprise a radially outer face comprising two circumferential grooves axially spaced from each other, this radially outer face comprising a fluid contact portion delimited axially by the two circumferential grooves and two bearing portions each being delimited axially by one of these circumferential grooves. The annular support may comprise a radially inner face having two axial ends respectively bearing on said bearing portions of the radially outer face of the ring, this radially inner face comprising a fluid contact portion axially between the bearing portions of this face. Said fluid damping cavity may be delimited radially by the respective fluid contact portions of the ring and the annular support, and axially by said circumferential grooves of the ring.

[0016] The invention also relates to a bearing comprising a device as defined above.

[0017] According to a first variant, this bearing may comprise a ball or roller bearing, the ring of the cage being configured to be mounted on an external ring of this bearing.

[0018] According to a second variant, this bearing may comprise an inner ring and rolling elements such as balls or rollers, the ring of the cage forming an outer ring constituting with the inner ring and the rolling elements a bearing.

[0019] The invention also relates to a turbomachine.

[0020] Preferably, this turbomachine is an aircraft turbomachine, which may comprise an accessory drive system, this accessory drive system comprising a device for taking power from a shaft of the turbomachine, this power taking device comprising a bearing as defined above.

[0021] The invention also relates to a method of assembling a device as defined above, according to an embodiment in which the annular support comprises a toothed crown and a fixing part, this method comprising: a step of fitting the toothed crown onto the ring by axial translation of the toothed crown relative to the ring so as to insert each tooth of the toothed crown into a respective inter-column opening of the cage; a step of fixing the fixing part to the toothed crown.

[0022] Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows. Brief description of the drawings

[0023] The following detailed description refers to the attached drawings in which: [ Fig. 1 ] is a schematic axial sectional view of a bypass turbojet engine including an accessory drive system; [ Fig. 2 ] is a schematic axial sectional view of an accessory drive system for an aircraft turbomachine, this system comprising an internal drive housing equipped with a rolling bearing for guiding a shaft of the turbomachine in rotation; [ Fig. 3] is a partial schematic perspective view of a rolling bearing damping device according to a first embodiment in accordance with the invention, this device comprising a cage and an annular support comprising a toothed crown and a fixing part, the cage being configured to be mounted on an outer ring of the bearing; [ Fig. 4 ] is a partial schematic perspective view of the cage and the toothed crown of the device of the figure 3 ; [ Fig. 5 ] is a partial schematic perspective view of the cage of the device of the figure 3 ; [ Fig. 6 ] is a partial schematic perspective view of a rolling bearing damping device according to a second embodiment in accordance with the invention, this device comprising a cage and an annular support comprising a toothed crown and a fixing part, the cage forming an external ring of the bearing. Detailed description of embodiments

[0024] There figure 1 shows a conventional twin-spool, twin-flow 100 turbojet engine.

[0025] The turbojet engine 100 comprising an accessory drive system 1, also known as “Accessory Drive Train” (ADT).

[0026] An accessory drive system 1 is shown in isolation in the figure 2 .

[0027] In a manner known per se, part of the energy generated by the turbojet engine 100 is taken to power various accessories powering this turbojet engine as well as equipment of the aircraft.

[0028] This sampling is generally carried out mechanically on a shaft 2 of the high pressure body of the turbojet.

[0029] To do this, the accessory drive system 1 typically comprises an internal drive box 3, also known as an “Internal Gear Box”. This box 3 houses a gear 4 driven by a pinion 5 secured to the shaft 2 of the turbojet, and thus forms a power extraction device.

[0030] Typically, the accessory drive system 1 comprises housings 7 and 8 as well as a transmission mechanism configured to transmit the mechanical energy thus taken to the accessories and equipment.

[0031] The transmission mechanism comprises a shaft 9 connecting the gear 4 of the internal drive housing 3 to a bevel gear 10 housed in the housing 7 so as to drive the pinions of this bevel gear 10 in rotation around their respective axis. The housing 7 forms an angle transmission housing also known as a “Transfer Gear Box”.

[0032] In this example, the shaft 9 is made of two portions 11 and 12 which extend into an arm 6 of an intermediate casing of the turbojet engine intended to extend through the secondary vein of the turbojet engine.

[0033] The transmission mechanism also comprises a shaft 13 connecting the bevel gear 10 to a gear 14 housed in the housing 8 which forms an accessory drive box, also known as “Accessory Gear Box” (AGB). In this example, the shaft 13 extends parallel to the longitudinal axis A1 of the turbojet engine 100.

[0034] The accessory drive box 8 usually supports various accessories, for example a generator, a starter, an alternator, a hydraulic pump, an engine lubrication unit, etc. Such accessories can thus be driven by the gear 14 to which the mechanical power taken from the shaft 2 of the turbojet 100 is transmitted.

[0035] The rotational guidance of the shaft 2 of the high pressure body, around the axis A1, is typically ensured by a rolling bearing 15 housed in the internal drive housing 3 (see figure 2 ).

[0036] The invention relates to a damping device 16 for such a rolling bearing 15, two embodiments of which are given as examples in figures 3 And 6 . Of course, the damping device 16 of the invention can be implemented in other rotating machines or to dampen any other turbomachine rolling bearing.

[0037] In each of the figures 3 to 6 , an orthogonal reference frame indicates axial directions A, radial R and circumferential C.

[0038] In these figures, only a circumferential section of each of the parts is shown, it being understood that each of these parts extends circumferentially around an axis of revolution so as to form an annular part.

[0039] By convention, the parts of the device 16 located towards the left of the figures 3 to 6 along the axial direction A form upstream parts while those located towards the right of these figures along the axial direction A form downstream parts.

[0040] When the damping device 16 is mounted on the rolling bearing 15 of the accessory drive system 1 of the figure 2 , this axis of revolution coincides with the longitudinal axis A1 along which the shaft 2 extends.

[0041] First of all, a first embodiment illustrated in the following is described below: figures 3 to 5 .

[0042] The damping device 16 comprises a cage 17 and an annular support 18.

[0043] In reference to the Figure 5 , the cage 17 comprises a fixing ring 19, a ring 20 and columns 21.

[0044] In this embodiment, the ring 20 is configured to be mounted on an outer ring of a bearing, for example the bearing of the bearing 15 of the figure 2 .

[0045] For this purpose, the ring 20 comprises a radially internal face 22 configured to match the radially external face of said external ring of the bearing.

[0046] In order to limit the axial displacement of the outer ring of the bearing relative to the ring 20, the latter preferably comprises axial stops arranged at two axial ends of this ring 20.

[0047] In the example of the Figure 5 , the ring 20 comprises at its upstream axial end a shoulder 23 forming an upstream axial stop for the outer ring of the bearing. This upstream axial stop 23 makes it possible to limit an axial displacement of the outer ring of the bearing relative to the ring 20 in a first direction going from downstream to upstream in the axial direction A.

[0048] To limit an axial displacement of the outer ring of the bearing relative to the ring 20 in a second direction opposite to said first direction, i.e. from upstream to downstream, the damping device 16 comprises for example a retaining ring (not shown) fixed on the radially internal face 22 of the ring 20 at its downstream axial end.

[0049] The shoulder 23 and the retaining ring thus make it possible to axially grip the outer ring of the bearing so as to secure this outer ring of the bearing with the ring 20 of the cage 17.

[0050] The axial retention of the outer ring of the bearing relative to the ring 20 of the cage 17 can be achieved by other means. For example, in an embodiment not shown, an additional retaining ring can be fixed on the radially internal face 22 of the ring 20 at its upstream axial end, in place of the shoulder 23. For another example, a shoulder can be produced on the ring 20 at its downstream end and a retaining ring can be fixed to the ring 20 at its upstream end.

[0051] Furthermore, the fixing of the retaining ring(s) may be achieved by any conventional means, for example using screws passing through the retaining ring(s) and received in corresponding threaded holes of the ring 20, and / or by cooperation of an external thread of the retaining ring(s) with an internal thread of the ring 20 (embodiments not shown).

[0052] Radially opposite the inner face 22, the ring 20 comprises a radially outer face 24 comprising two circumferential grooves 25 axially spaced from each other.

[0053] This radially external face 24 comprises a fluid contact portion 26 delimited axially by the two circumferential grooves 25 and two support portions 27 each being delimited axially by one of these circumferential grooves 25. The support portions 27 are therefore located at the upstream and downstream axial ends, respectively, of the ring 20.

[0054] The fluid contact portion 26 is intended to delimit a fluid damping cavity (see further below).

[0055] Concerning the fixing ring 19 of the cage 17, the latter has an internal diameter greater than the external diameter of the ring 20, so that the fixing ring 19 extends radially outside the ring 20 and at a distance from it. This difference in diameter is in particular determined as a function of the desired radial deformation range of the columns 21 (see further below).

[0056] The fixing ring 19 of the cage 17 comprises an axially upstream face 28 and an axially downstream face 29 defining a thickness of this ring 19. The axially upstream 28 and downstream 29 faces are each substantially parallel to the radial direction R so that this ring 19 can be pressed by its axially upstream face 28 against a face of a frame substantially perpendicular to the axis of revolution of the cage 17. The cage 17 can thus be fixed to such a frame by any conventional means, for example using screws (see further below).

[0057] In this example, the fixing ring 19 of the cage 17 is located at the right of the upstream axial end of the ring 20.

[0058] The fixing ring 19 is connected to the ring 20 by the columns 21. In this example, each column 21 comprises for this purpose a first end connected to the downstream axial end of the ring 20 and a second end connected to the fixing ring 19. Taking into account the relative radial position of the fixing ring 19 and the ring 20, the columns 21 each extend both axially and radially, that is to say obliquely relative to the axis of revolution of the cage 17.

[0059] The columns 21 are circumferentially spaced from each other so that, for each pair of circumferentially contiguous columns 21, they define between them an inter-column opening.

[0060] The cage 17 is thus perforated by the inter-column openings, which gives the cage a certain radial flexibility. In a manner known per se, the columns 21 are in fact dimensioned to deform radially under the action of a predetermined radial force so as to allow a radial displacement of the ring 20 relative to the fixing ring 19. This radial displacement is here limited radially outwards by the annular support 18 (see below).

[0061] In reference to the Figures 3 and 4 , the annular support 18 comprises a toothed crown 30 and a fixing part 31.

[0062] The toothed crown 30 comprises an annular base 32 carrying a plurality of teeth 33 which each extend radially through a respective inter-column opening of the cage 17 (see figure 4 ).

[0063] The annular base 32 of this toothed crown 30 comprises a radially internal face 34 having two axial ends respectively bearing on said bearing portions 27 of the radially external face 24 of the ring 20.

[0064] The radially internal face 34 of the toothed crown 30 comprises a portion of fluid contact axially between the support portions of this face 34.

[0065] When the cage 17 and the annular support 18 are assembled with each other, said fluid damping cavity is delimited radially on the one hand by the fluid contact portion 26 defined by the radially external face 24 of the ring 20 of the cage 17 and, on the other hand, by the fluid contact portion 34 defined by the radially internal face 34 of the toothed crown 30 of the annular support 18. Axially, this fluid damping cavity is delimited by the circumferential grooves 25 made in the ring 20 of the cage 17.

[0066] Thus, the cage 17 and the annular support 18 radially form between them a fluid damping cavity capable of forming a circumferential film of compressed fluid, this fluid typically being oil.

[0067] The oil is conveyed into the fluid damping cavity by any conventional means, for example using one or more channels and / or orifices made in the annular support 18, in particular in the toothed crown 30 and / or in the fixing part 31 of this annular support 18.

[0068] In this example, the ring 20 of the cage 17 is machined so that the diameter of its external face 24 at the level of the fluid contact portion 26 is less than the diameter of this external face 24 at the level of the support portions 27, in order to define a thickness of the compressed fluid film. Typically, the difference between these diameters can be between 0.15 mm and 0.4 mm.

[0069] Of course, the embodiment which has just been described is in no way limiting, the fluid damping cavity being able to have a different geometry, provided that this is formed radially between the ring 20 of the cage 17 and the annular support 18.

[0070] In reference to the figure 4 , the toothed crown 30 is furthermore dimensioned so that its radial dimension is less or substantially less than said difference between the internal diameter of the fixing ring 19 of the cage 17 and the external diameter of the ring 20 of this cage 17. Indeed, as can be deduced from the assembly method described below, the toothed crown 30 must be able to be inserted into the cage 17 by relative axial translation of these parts by passing the toothed crown 30 radially between the fixing ring 19 and the ring 20.

[0071] The fixing part 31 of the annular support 18 performs in this example a dual function of axial support and limitation of the radial displacement of the toothed crown 30 relative to the frame.

[0072] In reference to the figure 3 , the fixing part 31 comprises in this example three upstream 35, intermediate 36 and downstream 37 parts forming an “S” in a cross-sectional plane.

[0073] The upstream part 35 is a fixing part bearing against said axially downstream face 29 of the fixing ring 19 of the cage 17. The cage 17 and the fixing part 31 of the annular support 18 can thus be fixed to said frame using common fixing means such as screws.

[0074] The intermediate portion 36 of the fixing part 31 forms a radial stop for the ring 20 of the cage 17. Indeed, the fixing part 31 and the toothed crown 30 are fixed to each other so that these parts are integral with each other both radially, axially and circumferentially (see below for the fixing means). In this example, the fixing part 31 and the toothed crown 30 are fixed to each other in a position in which a radially external face of the teeth 33 of the toothed crown 30 is in abutment against a radially internal face of the intermediate portion 36 of the fixing part 31.

[0075] The downstream part 37 comprises in this example lugs which each bear against a downstream face of a respective tooth 33 of the toothed crown 30. Preferably, screws (not shown) are used to fix the lugs 37 against the teeth 33.

[0076] The annular support 18 thus forms a radial stop limiting the movement of the cage 17 radially outwards and allowing the supply of oil to the bearing and in particular to the fluid damping cavity.

[0077] The assembly of such a damping device 16 notably comprises a step of fitting the toothed crown 30 onto the ring 20 of the cage 17 by axial translation of this toothed crown 30 relative to the ring 20 so as to insert each tooth 33 of the toothed crown 30 into a respective inter-column opening of the cage 17.

[0078] After positioning the toothed crown 30 and the ring 20 according to the configuration illustrated in figure 4 , a step of fixing the fixing part 31 and the toothed crown 30 to each other is carried out.

[0079] The following description relates to the second embodiment illustrated in figure 6. This description is limited to the differences between the first and second embodiments.

[0080] In the example of the figure 6 , the ring 20 of the cage 17 directly forms the external ring of the bearing which equips the damping device 16.

[0081] For this purpose, the ring 20 forms a track 38 for the ball bearing.

[0082] In this example, the track 38 is located at a downstream axial end of the cage 17, and more specifically downstream relative to the fluid damping cavity.

[0083] Among other advantages, this configuration makes it possible in particular to improve the drainage of the space in which the balls move, by means of drainage orifices 39 which open downstream of the toothed crown 30.

[0084] Of course, the invention is not limited to the particular examples described above. For example, the ring 20 of the damping device 16 may be configured to be mounted on the periphery of a roller bearing or to form an outer ring of such a bearing.

Claims

1. Device (16) for damping a rolling bearing (15), this device (16) comprising an annular support (18) and a cage (17) extending axially along an axis of revolution (A1), this cage (17) comprising: - a fastening ring (19), - a ring (20) configured to be mounted on the periphery of the bearing (15) or to form an outer ring of the bearing (15), - stanchions (21) connecting the ring (20) to the fastening ring (19), these stanchions (21) extending obliquely with respect to said axis of revolution (A1) and being circumferentially spaced apart from one another such that, for each pair of circumferentially contiguous stanchions (21), these stanchions (21) define an inter-stanchion opening therebetween, the ring (20) and the annular support (18) forming radially therebetween a fluidic damping cavity capable of forming a circumferential compressed fluid film, this device (16) being characterised in that the annular support (18) comprises a plurality of teeth (33) each extending radially through a respective inter-stanchion opening of the cage (17), and in that the annular support (18) comprises a crown gear (30) and a fastening part (31), the crown gear (30) bearing said teeth (33) and delimiting said fluidic damping cavity, the fastening part (31) being fastened to the crown gear (30).

2. Device (16) according to claim 1, wherein each stanchion (21) of the cage (17) comprises a first end connected to a first axial end of the ring (20) and a second end connected to the fastening ring (19) and located axially next to a second axial end of the ring (20).

3. Device (16) according to claim 1 or 2, wherein the fastening part (31) of the annular support (18) bears against the fastening ring (19) of the cage (17).

4. Device (16) according to any preceding claims, wherein the fastening part (31) of the annular support (18) comprises tabs (37) each bearing against a respective tooth (33) of the crown gear (30).

5. Device (16) according to any preceding claims, wherein the ring (20) comprises a radially outer face (24) comprising two circumferential grooves (25) axially spaced apart from one another, this radially outer face (24) comprising a fluidic contact portion (26) delimited axially by the two circumferential grooves (25) and two bearing portions (27) each being delimited axially by one of these circumferential grooves (25), and wherein the annular support (18) comprises a radially inner face (34) having two axial ends respectively bearing on said bearing portions (27) of the radially outer face (24) of the ring (20), this radially inner face (34) comprising a fluidic contact portion axially between the bearing portions of this face (34), said fluidic damping cavity being delimited radially by the respective fluidic contact portions of the ring (20) and of the annular support (18), and axially by said circumferential grooves (25) of the ring (20).

6. Bearing comprising a device (16) according to any preceding claims and a ball or roller bearing (15), the ring (20) of the cage (17) being configured to be mounted on an outer ring of this bearing (15).

7. Bearing comprising a device (16) according to any preceding claims, an inner ring and rolling elements such as balls or rollers, the ring (20) of the cage (17) forming an outer ring establishing a bearing with the inner ring and the rolling elements.

8. Aircraft turbine engine, comprising an accessory drive train (1), this accessory drive train (1) comprising a device for drawing power (3) from a shaft (2) of the turbine engine, this device for drawing power (3) comprising a bearing according to claim 6 or 7.

9. Method for assembling a device (16) according to any one of claims 1 to 5, including the features of claim 3, this method comprising: - a step of interlocking the crown gear (30) on the ring (20) by axial translation of the crown gear (30) with respect to the ring (20) so as to insert each tooth (33) of the crown gear (30) into a respective inter-stanchion opening of the cage (17); - a step of fastening the fastening part (31) to the crown gear (30).