Device for guiding a shaft and for cooling a bearing for a gas generator

Abstract

The invention relates to a device (28) for guiding a shaft (20) about an axis (X) for a gas generator, the device comprising: - a rolling bearing (22); - a circuit (26) for lubricating the rolling bearing (22); - an annular casing (42) that extends around the bearing (22) comprising an inner recess (44) for mounting the outer race (22b); - a circuit (28) for cooling the outer race (22b) of the bearing (22) comprising: - at least one annular fluid-feed cavity (50) formed in the wall thickness (E) of the casing (42); - at least one annular fluid-discharge cavity (52, 52a, 52b) formed in the wall thickness (E) of the casing (42); and - an annular system (40) for cooling the outer race (22b) which is connected, respectively, to the feed and discharge cavities (50, 52, 52a, 52b).

Description

[0001] DESCRIPTION

[0002] TITLE: DEVICE FOR GUIDING A SHAFT AND COOLING A BEARING FOR A GAS GENERATOR

[0003] Technical field of the invention

[0004] The present invention relates to a device for guiding a shaft and cooling a bearing for a gas generator, such as a turbomachine or an auxiliary power unit.

[0005] Technical background

[0006] The state of the art includes in particular documents FR-A1 -3 098 560, CN-B- 110 905 653 and DE-A1 -10 2016 211569.

[0007] In the present application, the term "gas generator" means a machine which successively comprises at least one compressor, a combustion chamber and at least one turbine. Air is compressed in the compressor then mixed with fuel and burned in the combustion chamber. The combustion gases thus generated are expanded in the at least one turbine which drives the rotor of the at least one compressor. The two rotors may be integral.

[0008] There are several applications and technologies for gas generators. The gas generator can, for example, be a turbomachine, particularly an aircraft one, and comprise one or more bodies, each body comprising a shaft connecting a compressor rotor to a turbine rotor. The turbomachine can be a turbojet, a turboprop, etc. The gas generator can also be an auxiliary power unit, also called an APU (which is the acronym for Auxiliary Power Unit), which can equip an aircraft, for example.

[0009] The rotors and shafts of a gas generator are centered and guided in rotation by bearings which each comprise two rings, respectively internal and external, between which are mounted rolling elements such as balls or rollers for example.

[0010] These guide bearings must be lubricated during operation and are therefore associated with a lubrication circuit which generally uses oil.

[0011] These guide bearings also need to be cooled to dissipate the heat energy generated during operation. There are several solutions for this.

[0012] One solution is to use lubricating oil to cool the bearing. The bearing lubrication circuit is then a bearing lubrication and cooling circuit.

[0013] This solution does, however, have drawbacks. The circuit requires dedicated systems such as a pump, a reservoir, a filter, and an air / oil exchanger to evacuate the calories from the oil to the outside. The volume, flow rate, temperature, and calories to be evacuated that characterize this lubrication will determine the power of the pump, the size of the reservoir, the exchanger, the filter, as well as the use of certain materials (in view of the temperatures reached by the oil).

[0014] Another solution is to use a bearing lubrication and cooling system that uses only fuel instead of oil. This latter solution is not optimal because the fuel used for bearing lubrication is likely to be contaminated by particles generated by bearing wear. Contaminated fuel is unsuitable for the combustion chamber injectors (as it risks clogging them) and must therefore be discharged into the exhaust gases without being used for propulsion.

[0015] Another solution is to provide two separate and independent circuits for bearing lubrication and cooling. The lubrication circuit can use oil and the cooling circuit can use fuel, avoiding contact with the rolling elements. The fuel used for bearing cooling is heated by heat exchange with the bearing and can then be redirected to the combustion chamber for propulsion purposes, thereby extending the flight envelope and increasing the payload.

[0016] The invention provides an improvement which avoids at least some of the drawbacks of the prior art, and which is simple, effective and economical.

[0017] Summary of the invention

[0018] The invention relates to a device for guiding a shaft around an axis and for cooling a bearing for a gas generator, comprising:

[0019] - a rolling bearing centered on the axis and comprising an inner ring, an outer ring and rolling elements arranged between these rings,

[0020] - a rolling bearing lubrication circuit,

[0021] - an annular casing which extends around the bearing and which includes an internal housing for mounting the outer ring, this casing having a wall thickness measured radially relative to the axis, and

[0022] - a cooling circuit for the outer ring of the bearing, which is independent of the lubrication circuit, characterized in that the cooling circuit comprises:

[0023] - at least one coolant supply duct and at least one coolant discharge duct, formed in the wall thickness of the casing,

[0024] - at least one annular fluid supply cavity extending around the axis and formed in the wall thickness of the casing, this annular cavity being connected to said at least one supply conduit,

[0025] - at least one annular fluid discharge cavity extending around the axis and formed in the wall thickness of the casing, this annular cavity being connected to said at least one discharge conduit, and

[0026] - an annular system for cooling the outer ring which is connected respectively to the supply and discharge cavities, this system comprising at least one fluid passage which extends along the axis and which opens with a radial component towards the inside into the housing of the outer ring. One of the particularities of the guide device according to the invention is that its lubrication and cooling circuits are independent. In the present application, these circuits are independent insofar as the fluid which is used to cool the bearing is not used to lubricate it (on the other hand the fluid used to lubricate the bearing can participate in its cooling). The lubrication and cooling fluids are advantageously different. The fluids are not intended to mix in particular at the bearing.

[0027] Another feature of the device is that the bearing cooling circuit is essentially formed within the thickness of the casing, and is therefore optimized in terms of space. This thickness is not necessarily constant and can, on the contrary, vary along the axis.

[0028] Finally, another of the particularities of the device, which is advantageous, is linked to the fact that the fluid passage(s) open into the internal housing of the outer ring and extend in the axial direction. The opening of the passage(s) in the internal housing allows the cooling fluid to be in direct contact with the outer ring, which optimizes its cooling by direct contact and convection of this fluid with the outer ring. The axial component of the orientation of the passage(s) allows the cooling fluid to have a limited stroke in contact with the outer ring and therefore to reduce the risk of heating of the fluid in this contact. This orientation is for example preferred to a circumferential orientation around the ring, in which the fluid would risk heating up and not effectively cooling the ring over its entire circumference.

[0029] The device 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 system has a single fluid passage which has an annular shape around the axis;

[0031] - the single passage is empty; - the single passage is filled with a honeycomb structure; this honeycomb structure is preferably a three-dimensional lattice structure, for example of the type described in application FR-A1-3 096 110 or FR-A1-3 100 728;

[0032] - the single passage is connected to the supply cavity by a first series of orifices formed in the casing, and to the discharge cavity by a second series of orifices formed in the casing;

[0033] - the single passage comprises an annular bottom which is opposite the external ring and which has a convex domed shape in axial section;

[0034] - the supply and discharge cavities are symmetrical with respect to a plane perpendicular to said axis;

[0035] - the system has several fluid passages which are distributed around the axis;

[0036] - the feed cavity is a single feed cavity that extends around the fluid passages;

[0037] - the fluid passages are arranged between a first discharge cavity and a second discharge cavity;

[0038] - the supply cavity is connected to the first and second discharge cavities by all of the fluid passages;

[0039] - the supply cavity is connected to the first discharge cavity by first fluid passages, and to the second discharge cavity by second fluid passages which are interposed between the first fluid passages;

[0040] - the first and second discharge cavities are symmetrical with respect to a plane perpendicular to said axis;

[0041] - each of the supply and discharge cavities forms or comprises one or more volute(s) around the axis;

[0042] - each of the supply and discharge conduits extends mainly parallel to said axis;

[0043] -- the lubrication circuit is an oil circuit, -- the cooling circuit is a fuel circuit,

[0044] -- the device comprises a heat exchanger comprising a first part connected to the lubrication circuit, and a second part connected to the cooling circuit, and configured to ensure an exchange of calories between the lubricating and cooling fluids.

[0045] The invention further relates to a gas generator, comprising at least one device as described above, the gas generator being for example a turbomachine or an auxiliary power unit.

[0046] Brief description of the figures

[0047] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0048] [Fig. 1] Figure 1 is a very schematic view of a gas generator equipped with a guiding and cooling device according to the invention;

[0049] [Fig. 2] Figure 2 is a schematic view in axial section and in perspective of a guiding and cooling device, according to a first embodiment of the invention;

[0050] [Fig. 3] Figure 3 is a schematic axial sectional and perspective view of the guiding and cooling device of Figure 2, without the rolling bearing and the shaft which it guides;

[0051] [Fig. 4] Figure 4 is a schematic cutaway view in axial section over 270° and in perspective, of the circulation volumes of the cooling fluid in the device of Figure 2;

[0052] [Fig. 5] Figure 5 is a schematic axial sectional view of the device of Figure 2;

[0053] [Fig. 6] Figure 6 is a schematic view in axial section and in perspective of a guiding and cooling device, according to a second embodiment of the invention;

[0054] [Fig. 7] Figure 7 is a schematic axial sectional and perspective view of the guiding and cooling device of Figure 6, without the rolling bearing and the shaft which it guides; [Fig. 8] Figure 8 is a schematic axial sectional view of the device of Figure 6;

[0055] [Fig. 9] Figure 9 is a schematic cutaway view in axial section over 270° and in perspective, of the circulation volumes of the cooling fluid in the device of Figure 6;

[0056] [Fig. 10] Figure 10 is a schematic view in partial axial section over 270° and in perspective, of the circulation volumes of the cooling fluid in the device of Figure 6;

[0057] [Fig. 11] Figure 11 is a schematic view in axial section and in perspective of the circulation volumes of the cooling fluid in the device of Figure 6;

[0058] [Fig. 12] Figure 12 is a schematic view in axial section and in perspective of a guiding and cooling device, according to a third embodiment of the invention;

[0059] [Fig. 13] Figure 13 is a schematic axial sectional and perspective view of the guiding and cooling device of Figure 12, without the rolling bearing and the shaft which it guides;

[0060] [Fig. 14] Figure 14 is a schematic view in axial section over 270° and in perspective, of the circulation volumes of the cooling fluid in the device of Figure 12;

[0061] [Fig. 15] Figure 15 is a schematic axial sectional view of the device of Figure 12;

[0062] [Fig. 16] Figure 16 is a schematic view in axial section and in perspective of a guiding and cooling device, according to a fourth embodiment of the invention;

[0063] [Fig. 17a-17c] Figures 17a to 17c are schematic views of annular cavities in the form of volute(s) of the guiding and cooling device according to the invention;

[0064] [Fig. 18a-18b] Figures 18a and 18b are very schematic views of the connection between a conduit and an annular cavity of the guiding and cooling device according to the invention. Detailed description of the invention

[0065] Figure 1 represents in a very general and schematic manner a gas generator 10 for example of a turbomachine or an auxiliary power unit (APU), this turbomachine or this APU being able for example to equip an aircraft.

[0066] The gas generator 10 comprises at least one compressor (not shown), an annular combustion chamber 12 and at least one turbine 14. The combustion chamber 12 comprises fuel injectors 15.

[0067] The turbine 14 comprises a bladed rotor 16 which rotates inside a stator. The combustion gases 18 which circulate in the vein of the turbine 14 expand and drive the rotor 16 which is connected to a shaft 20. This shaft 20 connects for example the rotor 16 of the turbine 14 to a rotor of the compressor.

[0068] The shaft 20 is centered and guided in rotation around an axis X by one or more rolling bearing(s) 22, for example ball or roller bearings.

[0069] In the context of the present invention, the rolling bearing 22 is part of a guiding and cooling device 24 which further comprises a circuit 26 for lubricating the bearing and a circuit 28 for cooling this bearing.

[0070] The lubrication circuit 26 is preferably an oil circuit. This circuit 26 comprises a reservoir 30 of lubricating fluid (oil) of which an outlet 30a is connected by a pump 32 to at least one oil nozzle 34, for example via a heat exchanger (air / oil) 36. The nozzle 34 is configured to spray oil onto the bearing 22.

[0071] The reservoir 30 of the circuit 26 further comprises an inlet 30b connected to at least one oil recovery element at the level of the bearing 22.

[0072] The cooling circuit 28 is independent of the lubrication circuit 26 and preferably uses a different fluid, which is for example fuel. The circuit 28 comprises a reservoir 36 of cooling or heat transfer fluid (fuel) of which an outlet 36a is connected by a pump 38 to an inlet 40a of a system 40 for cooling the bearing 22. This system 40 comprises an outlet 40b which can be connected to the injector(s) 15, so that the fuel which has been used to cool the bearing 22 can subsequently be used to supply the combustion chamber 14.

[0073] The fuel is thus heated before supplying the chamber 12, which is advantageous. Furthermore, the calories taken by the fuel are not taken by the oil, which is therefore less hot, which improves the efficiency of the lubrication and can make it possible to undersize the exchanger 36, in the sense of reducing the size of the exchanger.

[0074] The cooling system 40 is also part, with the bearing 22, of the guiding and cooling device 24 within the meaning of the invention.

[0075] In a particular embodiment of the invention, the circuit 28 could also comprise a heat exchanger (not shown).

[0076] Although this is not visible in Figure 1, the bearing 22 comprises two rings, respectively inner and outer, between which are arranged rolling elements such as for example balls or rollers. In the context of the present invention, the cooling system 40 is configured to cool the outer ring of the bearing 22 by allowing direct contact of the outer ring with the fuel and therefore a direct exchange of calories between them.

[0077] We now refer to Figures 2 to 5 which illustrate a first embodiment of the invention.

[0078] The guiding and cooling device 24 of Figures 2 to 5 comprises:

[0079] - the rolling bearing 22 with its inner ring 22a, its outer ring 22b and its rolling elements 22c arranged between these rings 22a, 22b,

[0080] - a rolling bearing lubrication circuit (which is not shown but which corresponds for example to circuit 26 in figure 6),

[0081] - an annular casing 42 which extends around the bearing 22 and which comprises an internal housing 44 for mounting the external ring 22b, this casing 42 having a wall thickness E measured radially relative to the axis X, and

[0082] - a circuit 28 for cooling the outer ring 22b of the bearing, which is independent of the lubrication circuit and which is partly shown.

[0083] With regard to the wall thickness E of the casing 42, it can be seen that this is not constant and can vary from a minimum thickness E1 to a maximum thickness E2.

[0084] In the example shown, the casing 42 comprises an internal cylindrical surface 42a which has a diameter D1 and an internal cylindrical surface 42b which has a diameter D2 less than D1. The housing 44 of the external ring 22b is located inside the surface 42a, and in the vicinity of the junction between the surfaces 42a, 42b which forms an annular shoulder 42c against which the external ring 22b is shaped to come into axial support once installed. The internal ring 22a is mounted on the shaft 20 and can also come into axial support on a shoulder 20a of the shaft 20. In the embodiment shown, the shaft 20 and the casing 42 are arranged axially relative to each other so that the shoulders 20a, 42c are located in the same plane perpendicular to the shaft, the rings 22a, 22b having the same length in the axial direction.The rings 22a, 22b can be immobilized axially against the shoulders 20a, 42c by screwing nuts respectively onto the shaft 20 and into the casing 42.

[0085] The cooling circuit 28 includes:

[0086] - at least one coolant supply duct 46 and at least one coolant discharge duct 48, formed in the wall thickness E of the casing 42,

[0087] - at least one annular fluid supply cavity 50 extending around the axis X and formed in this wall thickness E, this annular cavity 50 being connected to the supply conduit(s) 46,

[0088] - at least one annular fluid discharge cavity 52 extending around the axis X and formed in this wall thickness E, this annular cavity 52 being connected to said discharge conduit(s) 48, and - the annular system 40 for cooling the external ring 22b which is connected respectively to the supply and discharge cavities 50, 52.

[0089] In the example shown, the circuit 28 comprises a single supply duct 46. This duct 46 has an elongated shape along the axis X and comprises a longitudinal end which is connected to the cavity 50 and which opens into this cavity 50. As illustrated in FIG. 4, this duct 46 has, for example, a generally rectangular cross-section.

[0090] The supply cavity 50 is here located on one side of the cooling system 40, and is more precisely arranged between the conduit 46 and this system 40. As in the example shown, the cavity 50 may have a generally triangular or trapezoidal axial section and therefore have a fluid passage section which evolves along the axis X and in particular which decreases along this axis, from the conduit 46 to the system 40.

[0091] The evacuation cavity 52 is here located on an opposite side of the cooling system 40. As in the example shown, the cavity 50 may have a generally triangular or trapezoidal axial section and therefore have a fluid passage section which evolves along the axis X and in particular which increases along this axis from the conduit 46.

[0092] It can be seen in the drawings and in particular in figure 5 that the cavities 50, 52 can be symmetrical with respect to a plane H perpendicular to the axis X and passing between the cavities 50, 52 (figure 5).

[0093] In the example shown, the circuit 28 comprises a single discharge duct 48. This duct 48 has an elongated shape along the axis and comprises a longitudinal end which is bent and connected to the cavity 52 and which opens into this cavity 52. ​​As illustrated in FIG. 4, this duct 48 has, for example, a generally rectangular cross-section. The figures further show that the ducts 46, 48 may be arranged one above the other, and may thus be cut by the same plane passing through the axis X (FIG. 5). The cavity 50 is connected to the cooling system 40 by a first series of orifices 58 which are preferably regularly distributed around the axis X. These orifices 58 are oriented mainly axially but may be inclined, for example in the tangential direction or in the radial direction.In the example shown, it can be seen that the orifices 58 are inclined radially inwards from their ends connected to the cavity 50, to their ends connected to the system 40.

[0094] The number of these 58 holes is for example greater than 30.

[0095] The cavity 52 is connected to the cooling system 40 by a second series of orifices 60 which are preferably regularly distributed around the axis X. These orifices 60 are oriented mainly axially but can be inclined, for example in a tangential direction or in a radial direction. In the example shown, it can be seen that the orifices are inclined radially inwards from their ends connected to the cavity 52, to their ends connected to the system 40.

[0096] The orifices 58, 60 are also arranged symmetrically with respect to the plane H (figure 5).

[0097] It is also noted that the cavities 50, 52 each have a reduction in their passage section around the axis X. It is noted in Figure 4 that these cavities 50, 52 have an axial dimension which decreases between 0° and 270° and then again until the ring closes (i.e. over the rest of the circumference), this in order to allow the good distribution of the supply pressures in the orifices 58. Otherwise, the fluid would risk passing mainly through the orifices 50 which are opposite the supply 46.

[0098] According to the invention, the system 40 comprises at least one fluid passage 62 which extends along the axis X and which opens radially inwards into the housing 44 of the external ring 22b.

[0099] In the first embodiment, the system 40 comprises a single fluid passage 62 which has an annular shape around the axis X. In the example shown, the passage 62 is located between the two cavities 50, 52, and is empty here.

[0100] In the embodiment variant of figure 16, this passage 62 is on the contrary filled with a honeycomb or porous structure 64 of the trellis or lattice type for example.

[0101] The passage 62 is here delimited radially outwards by an annular bottom 62a which is intended to be opposite the external ring 22b of the bearing 22.

[0102] This bottom 62a advantageously has in axial section a convex domed shape as illustrated in the drawings. This makes it possible to locally reduce the fluid passage section around the ring 22b and to accelerate it in contact with the ring 22b to optimize the cooling of the latter. This also makes it possible to limit the fuel stagnation zones inside the passage 62.

[0103] The inner periphery of the passage 62 is closed by the outer ring 22b of the bearing 22.

[0104] Plane H is also a plane of symmetry of passage 62 (figure 5).

[0105] In Figures 2, 3 and 5, the arrows show the flow of the cooling fluid (preferably fuel) in the circuit 28. The fluid circulates axially over and in contact with the outer ring 22b, in particular in the passage 62. In the case of the variant of Figure 16, the cooling of the ring 22b by conduction is added to the cooling by convection when the structure 64 is in contact with the ring 22b inside the housing 44. In this structure 64, the path of the fluid may be sinuous on a very small scale but its general orientation remains parallel to the X axis.

[0106] Reference is now made to Figures 6 to 11 which illustrate another embodiment of the invention.

[0107] As in the previous embodiment, the guiding and cooling device 24 comprises a rolling bearing 22, a bearing lubrication circuit (circuit not shown), an annular casing 42, and a circuit 28 for cooling the outer ring 22b of the bearing.

[0108] The following description focuses essentially on the technical differences between the embodiment of figures 6 to 11 and that previously described, the other characteristics of these embodiments being identical or similar.

[0109] The circuit 28 comprises a single supply conduit 46. This conduit 46 has an elongated shape along the axis and comprises a longitudinal end which is connected to the cavity 50 and which opens into this cavity 50. As illustrated in FIG. 4, this conduit 46 has, for example, a generally rectangular cross-section.

[0110] The feed cavity 50 is here located around the system 40. The cavity 50 may have a generally rectangular shape in axial section.

[0111] It can be seen that the cavity 50 has a reduction in its passage section around the X axis. It can be seen in Figures 9 to 11 that this cavity 50 has a radial dimension which decreases between 0° and 270° and then again until the ring closes.

[0112] The circuit 28 comprises two evacuation cavities 52a, 52b which are located on either side of the cooling system 40.

[0113] Each of the cavities 52a, 52b may have a generally triangular shape in axial section and therefore have a fluid passage section which evolves along the X axis.

[0114] It is also noted that the cavities 52a, 52b each have a reduction in their passage section around the X axis. It is noted in Figures 9 to 11 that these cavities 52a, 52b have an axial dimension which decreases between 0° and 270° and then again until the ring closes.

[0115] It can be seen in the drawings and in particular in figure 58 that the cavities 52a, 52b can be symmetrical with respect to a plane H perpendicular to the axis X and passing between the cavities 52a, 52b (figure 8).

[0116] The circuit 28 comprises two discharge conduits 48a, 48b. The conduits 48a, 48b are similar to the conduits 46, 48 described above. The conduit 48a has an elongated shape along the axis and comprises a longitudinal end which is connected to the cavity 52a and which opens into this cavity 52a. As illustrated in FIG. 9, this conduit 48a has, for example, a generally rectangular cross-section.

[0117] The conduit 48b has an elongated shape along the axis and comprises a longitudinal end which is bent and connected to the cavity 52b and which opens into this cavity 52b. As illustrated in FIG. 9, this conduit 48b has, for example, a generally rectangular cross-sectional shape.

[0118] The figures further show that the conduits 46, 48a, 48b can be arranged one above the other, and can thus be cut by the same plane passing through the X axis (figure 8).

[0119] The cavity 50 is connected to the cavity 52a by first passages 62a which are distributed around the axis X. The cavity 50 is connected to the cavity 52b by second passages 62b which are distributed around the axis X. The passages 62a are interposed between the passages 62b.

[0120] The number of passages 62a is for example greater than 30. The number of passages 62b is for example greater than 30.

[0121] In particular, it can be seen in Figure 9 that each of the passages 62a, 62b has a general L-shape and comprises a first branch with a principal axial orientation, which extends from the second branch to the cavity 52a or 52b, and a second branch with a principal radial orientation, which extends from the first branch outwards to the cavity 50.

[0122] Each of the passages 62a, 62b comprises a radially inner end which is closed by the outer ring 22b of the bearing 22.

[0123] In Figures 6 to 8, the arrows show the flow of the cooling fluid (preferably fuel) in the circuit 28. The fluid circulates axially over and in contact with the outer ring 22b, in particular in the first axial branches of the passages 62a, 62b. The circulations of the fluid in the passages 62a, 62b are advantageously in opposition. Reference is now made to Figures 12 to 15 which illustrate another embodiment of the invention.

[0124] This embodiment differs from the previous embodiment essentially in that the cavity 50 is connected to the cavities 52a, 52b by all of the passages 62'. These passages 62' are distributed around the X axis and each have, for example, a general T shape.

[0125] Each of the passages 62' comprises a first branch with a principal axial orientation, which extends between the cavities 52a, 52b and opens respectively into these cavities 52a, 52b, and a second branch with a principal radial orientation, which extends from the middle of the first branch outwards to the cavity 50.

[0126] The number of 62' passages is for example greater than 30.

[0127] In Figures 12 and 15, the arrows show the flow of the cooling fluid (preferably fuel) in the circuit 28. The fluid circulates axially over and in contact with the outer ring 22b, in particular in the first axial branches of the passages 62'. It can be seen in Figure 15 that a portion of the fluid coming from the cavity 50 circulates in a first direction along the axis X, from this cavity 50 to the cavity 52a, and another portion of the fluid coming from the cavity 50 circulates in a second opposite direction along the axis, from this cavity 50 to the cavity 52b.

[0128] Figures 17a to 17c show particular embodiments of the supply cavities 50 and discharge cavities 52, 52a, 52b. Each of these cavities may comprise or form at least one volute, which extends around the axis X.

[0129] In the case of Figure 17a, the cavity 50, 52, 52a, 52b comprises a single volute which extends over substantially 360° around the axis X. This volute has a passage section which evolves around the axis X and which is maximum at the level of its connection to the corresponding conduit 46, 48, 48a, 48b, and which is minimum at the circumferential end of the volute opposite this conduit. Volutes of the type of that of Figure 17a are visible in Figures 9, 10, 11 and 14.

[0130] In the case of Figure 17b, the cavity 50, 52, 52a, 52b comprises four volutes regularly distributed around the axis X and each having an angular extent of approximately 90° around this axis X. Each volute has a passage section which is maximum in its middle which is connected to the corresponding conduit 46, 48, 48a, 48b, and which is minimum at its circumferential ends. The volutes are connected to each other by their circumferential ends.

[0131] In the case of Figure 17c, the cavity 50, 52, 52a, 52b comprises a single volute which extends substantially 360° around the axis. This volute has a passage section which is maximum in its middle which is connected to the corresponding conduit 46, 48, 48a, 48b, and which is minimum at its circumferential ends. The circumferential ends of the volute are connected to each other.

[0132] Figures 18a and 18b respectively show two configurations for connecting a conduit 46, 48, 48a, 48b to a cavity 50, 52, 52a, 52b, in a device according to the invention. In the case of Figure 18a, the conduit 46, 48, 48a, 48b is entirely straight and opens axially into the cavity 50, 52, 52a, 52b. In the case of Figure 18b, the conduit 46, 48, 48a, 48b has a bent end and opens in the circumferential direction into the cavity 50, 52, 52a, 52b.

[0133] Given the complexity of the casing 22 and the cooling circuit 28 which it partly contains, it could be produced by additive manufacturing.

Claims

CLAIMS 1. Device (28) for guiding a shaft (20) around an axis (X) and for cooling a bearing for a gas generator, comprising: - a rolling bearing (22) centered on the axis (X) and comprising an inner ring (22a), an outer ring (22b) and rolling elements (22c) arranged between these rings (22a, 22b), - a circuit (26) for lubricating the rolling bearing (22), - an annular casing (42) which extends around the bearing (22) and which comprises an internal housing (44) for mounting the external ring (22b), this casing (42) having a wall thickness (E) measured radially relative to the axis (X), and - a circuit (28) for cooling the outer ring (22b) of the bearing (22), which is independent of the lubrication circuit (26), characterized in that the cooling circuit (28) comprises: - at least one cooling fluid supply duct (46) and at least one cooling fluid discharge duct (48, 48a, 48b), formed in the wall thickness (E) of the casing (42), - at least one annular fluid supply cavity (50) extending around the axis (X) and formed in the wall thickness (E) of the casing (42), this annular cavity (50) being connected to said at least one supply conduit (46), - at least one annular cavity (52, 52a, 52b) for discharging fluid extending around the axis (X) and formed in the wall thickness (E) of the casing (42), this annular cavity (52, 52a, 52b) being connected to said at least one discharge conduit (48, 48a, 48b), and - an annular system (40) for cooling the outer ring (22b) which is connected respectively to the supply and discharge cavities (50, 52, 52a, 52b), this system (40) comprising at least one fluid passage (62, 62a, 62b, 62') which extends along the axis (X) and which opens with a radial component inwards in the housing (44) of the outer ring (22b).

2. Device (28) according to claim 1, wherein the system (40) comprises a single fluid passage (62) which has an annular shape around the axis (X).

3. Device (28) according to claim 2, in which the single passage (62) is empty.

4. Device (28) according to claim 2, in which the single passage (62) is filled with a honeycomb structure (64).

5. Device (28) according to one of claims 2 to 4, in which the single passage (62) is connected to the supply cavity (50) by a first series of orifices (58) formed in the casing (42), and to the discharge cavity (52) by a second series of orifices (60) formed in the casing (42).

6. Device (28) according to one of claims 2 to 4, in which the single passage (62) comprises an annular bottom 62a) which is opposite the external ring (22b) and which has a convex domed shape in axial section.

7. Device (28) according to one of the preceding claims, in which the supply and discharge cavities (50, 52) are symmetrical with respect to a plane (H) perpendicular to said axis (X).

8. Device (28) according to claim 1, in which the system (40) comprises several fluid passages (62a, 62b, 62') which are distributed around the axis (X).

9. The device (28) of claim 8, wherein the supply cavity (50) is a single supply cavity that extends around the fluid passages (62a, 62b, 62').

10. Device (28) according to claim 8 or 9, wherein the fluid passages (62a, 62b, 62') are arranged between a first discharge cavity (52a) and a second discharge cavity (52b).

11. Device (28) according to claims 9 and 10 taken together, wherein the supply cavity (50) is connected to the first and second discharge cavities (52a, 52b) by the entirety of the fluid passages (62').

12. Device (28) according to claims 9 and 10 taken together, wherein the supply cavity (50) is connected to the first discharge cavity (52a) by first fluid passages (62a), and to the second discharge cavity (52b) by second fluid passages (62b) which are interposed between the first fluid passages (62a).

13. Device (28) according to one of claims 10 to 12 in which the first and second evacuation cavities (52a, 52b) are symmetrical with respect to a plane (H) perpendicular to said axis (X).

14. Device (28) according to one of the preceding claims, in which each of the supply and discharge cavities (52a, 52b) forms or comprises one or more volute(s) around the axis (X).

15. Gas generator, comprising at least one device according to one of the preceding claims, the gas generator being for example a turbomachine or an auxiliary power unit.

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