Anti-clogging cover for a turbomachine's fire suppression system and corresponding fire suppression system

Abstract

The invention relates to an annular anti-clogging cover (40) with axis C for a fire suppression system (30) of a turbomachine (1), particularly an aircraft turbomachine. The turbomachine comprises an annular cover arranged in an annular cavity, comprising a first radial flange fixed to a second radial flange via first fastening members. According to the invention, the cover (40) is intended to be fixed to an annular bearing surface (36) of the lid and to cover the first fastening members (27). The cover comprises an annular bottom wall (41) having a central bore and an annular skirt (42) extending from the bottom wall along axis C. The annular skirt comprises positioning members (61) intended to engage with receiving elements (62) of the lid. The positioning members and the receiving element form complementary fastening means (60) configured to axially retain the cover (40) on the lid (31).Abbreviated figure: Figure 10.

Description

Title of the invention: ANTI-OBSTRUCTION COVER FOR A FIRE-FIGHTING SYSTEM OF A TURBOMACHINE AND CORRESPONDING FIRE-FIGHTING SYSTEM Field of invention

[0001] The present invention relates to the general field of turbomachines. It relates in particular to an anti-obstruction cover for a fire-fighting system installed in a cavity supplied with cooling air and close to a hot zone of a turbomachine. The invention also relates to a fire-fighting system equipped with such a cover and a turbomachine comprising such a fire-fighting system and a method of mounting the fire-fighting system. Technical background

[0002] A turbomachine for an aircraft generally comprises, from upstream to downstream and depending on the direction of flow of the gases in the turbomachine, a compressor section, a combustion chamber, a turbine section. The compressor section comprises for example a low-pressure compressor and a high-pressure compressor and the turbine section comprises for example a high-pressure turbine and a low-pressure turbine. The turbomachine may comprise a free turbine which is driven by the gases at the outlet of the high-pressure turbine or the low-pressure turbine located upstream thereof. The rotating parts of these compressors and / or turbines such as shafts and wheels are driven and / or guided in rotation using rolling bearings which are housed in cooling and lubrication enclosures.The cooling and lubrication enclosures are arranged near so-called hot zones which are generally exposed to high temperatures because these parts are crossed by the gases from the turbomachine.

[0003] For this purpose, the turbomachines are equipped with a lubrication system for lubricating and / or cooling the rolling bearing(s) required for guiding the shafts and which are mounted in the cooling and lubrication enclosures. The turbomachines are also equipped with a cooling device for cooling the parts located in hot zones of the turbomachine and for pressurizing the enclosures. Generally, the lubrication system and the cooling device are arranged in restricted spaces favoring the proximity of the lubrication circuit of the lubrication system with rotor parts located in the hot zone of the turbomachine. In the event of a leak, the lubricant may encounter in these zones, conditions of temperature, pressure, flow speed of the cooling air and level of turbulence of the cooling air which are favorable to self-ignition. This risk of self-ignition could cause damage to rotor parts, or even the rupture and / or release of parts rotating at high speed.

[0004] The invention aims to avoid the aforementioned drawbacks. Summary of the invention

[0005] The objective of the invention is to provide an optimal solution making it possible to guarantee the circulation of cooling air in a hot zone of the turbomachine and to limit, or even prevent, an ignition of a combustible fluid in said hot zone while being simple and economical.

[0006] This objective is achieved in accordance with the invention by means of an annular anti-obstruction cover of axis C for a fire-fighting system of a turbomachine, such as an aircraft turbojet or turboprop, the turbomachine comprising an annular cover intended to be arranged in an annular cavity of the turbomachine in which cooling air circulates, the cover comprising a first radial flange fixed to a second radial flange by means of first fixing members distributed regularly around the longitudinal axis X, the cover being intended to be fixed to an annular bearing surface of the cover and to cover the first fixing members, the cover comprising an annular bottom wall comprising a central bore intended to be crossed by an annular wall of the cover and an annular skirt extending from the bottom wall along the axis C,and in that the annular skirt comprises positioning members intended to engage in receiving elements of the cover, the positioning members and the receiving element forming complementary fixing means which are configured so as to axially hold the hood on the cover.

[0007] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, the cover thus held firmly on the lid prevents, in the event of loosening of the first fixing members, the cover from obstructing the cavity and the flow path of cooling air towards the internal bore of the disc. Such a cover also makes it possible to guide the cooling air towards the bore and to prevent recirculation of air in the cavity around the first fixing members which could generate favorable conditions for a fire to start.

[0008] The hood includes one or more of the following features, taken alone or in combination:

[0009] - the complementary fixing means comprise circumferential grooves entials which are arranged on the cover and a plurality of lugs which are arranged on the hood and which extend radially towards the axis C from an internal surface of the annular skirt, the lugs being regularly distributed around the axis C and being intended to engage by sliding in the circumferential grooves.

[0010] - the first radial flange comprises a plurality of first holes and the second radial flange comprises a plurality of second holes intended to cooperate with each other and to receive the first fixing members.

[0011] - the bottom wall comprises a plurality of third through holes intended for cooperate with fourth holes formed in the annular surface of the cover, the third and fourth holes being intended to receive second fixing members.

[0012] - the second fixing members each comprise a head and the bottom wall comprises housings which each open into a third hole, each housing being intended to house and contain the head of the second fixing members.

[0013] - the number of fixing members is between 4 and 8.

[0014] - the central bore is delimited by an internal annular surface intended to be in contact with an annular bearing surface of the cover and in that the cover comprises an annular edge which is defined in a plane PI upstream of a plane P2 in which a bearing surface of the head in the cover is defined.

[0015] - the hood is fixed on the annular surface of the cover by means of second fixing organs.

[0016] The invention also relates to a fire-fighting system for a turbomachine comprising at least one turbine connected to a shaft of longitudinal axis X and an annular bearing support which is intended to carry at least in part a bearing for guiding the rotation of the shaft and which comprises a first radial flange, the system comprising an anti-obstruction cover as mentioned above, and a cover which is intended to be mounted on the bearing support and which is provided with the second radial flange fixed to the first radial flange by the first fixing members distributed regularly around the longitudinal axis X.

[0017] The fire protection system comprises one or more of the following features, taken alone or in combination:

[0018] - the cover comprises a plurality of projections extending radially from a radially external wall of the cover and comprising the circumferential grooves, each circumferential groove extending in a circumferential direction around the axis C and being intended to receive a lug.

[0019] - the projections comprise first projections each comprising a groove cir conference and second projections each comprising a fourth hole, the first projections and the second projections being alternated around the axis of the cover.

[0020] - the diffuser splits the annular cavity into a first cavity and a second cavity cavity.

[0021] The invention also relates to a turbomachine comprising a turbomachine in particular of an aircraft, having a longitudinal axis X and comprising a turbine connected to a shaft providing mechanical power, an annular cavity arranged upstream of a first stage of the turbine, a cooling device intended to supply cooling gas to the cavity and a fire-fighting system as mentioned above, the fire-fighting system being arranged in the cavity.

[0022] The turbomachine comprises one or more of the following characteristics, taken alone or in combination:

[0023] - the turbine is arranged downstream of a turbine section.

[0024] - the shaft is a power shaft providing mechanical power to a shaft exit.

[0025] - the turbine is a linked turbine or a free turbine.

[0026] The invention further relates to an aircraft comprising at least one turbomachine as mentioned above.

[0027] The invention also relates to a method of mounting a fire-fighting system as mentioned above, the method comprising the following steps:

[0028] - placing the hood on the cover so that the bottom wall is in contact with the annular surface of the cover,

[0029] - performing a rotation of the hood around the longitudinal axis so as to engage the lugs in the circumferential grooves,

[0030] - fixing the hood on the cover via the second fixing members. Brief description of the figures

[0031] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0032] [Fig-1] [Fig. 1] represents an axial and partial sectional view of an example of a turbomachine comprising a free turbine according to the invention;

[0033] [Fig.2] [Fig.2] is a perspective and exploded view of a fire-fighting system intended to be mounted in a turbomachine according to the invention;

[0034] [Fig.3] [Fig.3] shows in perspective an example of a cover for a turbomachine member according to the invention;

[0035] [Fig.4] [Fig.4] is a perspective view of an example of a hood intended to be mounted on a cover such as that illustrated in [Fig.3] according to the invention;

[0036] [Fig.5] [Fig.5] is an axial sectional view of a fire-fighting system arranged in a pressurized cavity of a turbomachine according to the invention;

[0037] [Fig.6] [Fig.6] is an axial sectional and perspective view of an anti- fire arranged in a pressurized cavity of a turbomachine, the system comprising a hood fixed on a cover according to the invention;

[0038] [Fig.7] [Fig.7] represents in perspective a step of installing a hood on a cover of a turbomachine component according to the invention;

[0039] [Fig.8] [Fig.8] represents a cross-sectional and perspective view of a hood mounted on a cover with positioning members facing recesses in the cover according to the invention;

[0040] [Fig.9] [Fig.9] is a perspective, partial, downstream view of a hood mounted on a cover according to the invention;

[0041] [Fig. 10] [Fig. 10] illustrates in axial section complementary fixing means according to the invention; Detailed description of the invention

[0042] [Fig.l] partially illustrates a turbomachine 1, such as a turbojet, a turboprop or a turboshaft engine. This turbomachine is intended to be mounted in an aircraft such as an airplane or a helicopter.

[0043] In the present application, the terms "upstream", "downstream", "axial" and "axially" are defined with respect to the direction of circulation of the gases in the turbomachine and also along the longitudinal axis X (and even from left to right in [Fig.l]). The terms "radial", "radially", "internal" and "external" are also defined with respect to a radial axis Z which is perpendicular to the axis X of the turbomachine.

[0044] Generally speaking, a turbomachine, in particular an aircraft turbomachine, with a longitudinal axis X, comprises, from upstream to downstream and in the direction of flow of the gas or air flows, a compressor section, a combustion chamber, and a turbine section. These elements form a gas generator 2. The compressor section may comprise a low-pressure compressor and a high-pressure compressor. The turbine section may comprise a low-pressure turbine and a high-pressure turbine. These turbines are known as a linked turbine. Each compressor (low or high pressure) and each turbine (low or high pressure) comprises one or more stages respectively. Each stage comprises a wheel of moving blades which is mounted upstream or downstream of a wheel of fixed blades (or stator blades).The rotors of the low-pressure compressor and the low-pressure turbine are connected to each other by a low-pressure shaft centered on the longitudinal axis X to form a low-pressure body. Similarly, the rotors of the high-pressure compressor and the high-pressure turbine are connected to each other by a high-pressure shaft centered on the longitudinal axis X to form a high-pressure body. The turbomachine may comprise a fan (not shown) upstream of the compressor section. This may also comprise an exhaust nozzle downstream of the turbine section. gas. Air entering the compressor section passes through the combustion chamber which emits combustion gases to the turbine section comprising at least one linked turbine.

[0045] Referring to [Fig.l], the turbomachine comprises an additional turbine 3 called free turbine 3 which is mounted downstream of the gas generator 2 and in particular downstream of the high pressure turbine or the low pressure turbine (of the turbine section). The gases from the gas generator 2 are sent to the free turbine 3 which drives a power shaft (not shown). In this example, the free turbine 3 is placed upstream of the exhaust nozzle or as a replacement for the latter. The power shaft provides the useful mechanical power to an output shaft for the propulsion of the aircraft. The power shaft is separate from the high pressure and / or low pressure shafts and is coaxial with them. The free turbine 3 here comprises a turbine stage with a movable wheel and a fixed wheel. The movable wheel comprises an annular disc 5 from which several movable blades 6 extend radially.The latter are distributed regularly around the disc 5 and pass through a primary vein in which a primary flow circulates. The disc 5 is driven in rotation around the longitudinal axis X by a shaft (here the power shaft) which passes through its internal bore 7 (turned towards the axis X). The fixed wheel is composed of fixed blades called distributors 8 and which are arranged upstream of the moving blades 6.

[0046] The disc 5 comprises an annular rim 9 which extends from a web 10 of the disc 5 along the longitudinal axis. The annular rim 9 also extends circumferentially around the longitudinal axis X. The annular rim 9 carries a sealing device 11 intended to cooperate with a radially internal end 12a of a first flange 12. The sealing device 11 is advantageously a labyrinth seal which comprises several wipers or blades extending radially and circumferentially around the longitudinal axis from the wall of the annular rim 9. These wipers are also arranged parallel along the longitudinal axis X. The first flange 12 is annular and is mounted upstream of the web 10 of the disc 5. The radially internal end 12a also carries an abradable coating arranged opposite the wipers to guarantee the sealing of the sealing device 11.The first flange 12 is also connected to a radially internal platform 13 of the upstream distributor.

[0047] The turbomachine 1 generally comprises a device 14 for cooling the disk 5 of the free turbine 3 (or one of the linked turbines). The cooling device 14 is supplied with air which is taken upstream of the turbomachine. Generally, the cooling air is taken from the high-pressure or low-pressure compressor. The cooling device 14 comprises an external pipe (not shown) which bypasses the disks of the turbine section in which circulating cooling air. The external piping is coupled to an internal pipe 18 which is also connected to a rear bearing housing 15 which comprises a first wall 15a and a second wall 15b connected to a fixed structure of the turbomachine. The housing 15 is a part of revolution around the longitudinal axis. The cooling device 14 comprises injection means intended to project the cooling air into an annular cavity 16 arranged upstream of the disk 5 of the free turbine. The injection means are formed in the rear bearing housing 15. This annular cavity 16 is in particular located upstream of the first stage of the free turbine. The injection means here comprise injectors 17 which are coupled to the air pipe 18 and which open into the annular cavity 16. The injectors 17 are orifices. Alternatively, the injectors are nozzles.The injectors 17 are distributed regularly around the longitudinal axis. The injectors 17 are advantageously placed substantially opposite the disc 5 of the free turbine 3. Each injector 17 has an axis parallel to the longitudinal axis X. In the present example, there are thirty-two injectors 17.

[0048] A structural part 28 is mounted on the rear bearing housing 15. The structural part 28 is an annular part which has an axis centered on the longitudinal axis X and which has a U-shaped (pin-shaped) radial section. This makes it possible to make the connection between the housing 15 and the distributor 8. In particular, this makes it possible to make the connection between the so-called "hot" part and the so-called "cold" part of the rear bearing housing 15. This is also flexible. Due to its flexibility, the structural part 28 absorbs deformations due to thermal differences.

[0049] The turbomachine 1 comprises several bearings which allow the low pressure shaft, the high pressure shaft and / or the power shaft of the free turbine 3 to be guided in rotation. The bearings are generally arranged in different enclosures, such as the lubrication and cooling enclosure 19, which are supplied with lubricant, here oil in the form of a mist, coming from a lubrication system. The enclosure 19 is pressurized to contain the oil in a sealed manner therein and also in the form of a mist. The oil mist allows a homogeneous distribution of the oil on the components of the turbomachine to be lubricated.

[0050] The pressurization of the enclosure 19 is obtained by injecting air which is taken from the compressor(s) or the blower. The air which is taken for the pressurization of the enclosures uses the same circuit as that for cooling the disks. Preferably, the cooling air is taken upstream of the blower so that the temperature of the cooling air is not too high and so that it can effectively cool the components of the turbomachine. The annular cavity 16 is arranged radially around the enclosure 19 and is separated from it by a cover 31 described below. The cover itself is arranged radially at the exterior of a bearing support which partly delimits the enclosure 19.

[0051] With reference to [Fig. 1], the power shaft is guided in rotation by a bearing 20 located downstream of it and which is arranged in the enclosure 19. This bearing 20 cooperates with a downstream bearing support 21 which is generally fixed to a fixed structure of the turbomachine. The downstream bearing 20 is advantageously a rolling bearing. The latter comprises an inner ring and an outer ring between which the rolling members are arranged. The rolling members are for example rollers.

[0052] In Figures 2, 5 and 6, the bearing support 21 has a shape of revolution extending around an axis A which is coaxial with the longitudinal axis X of the turbomachine in the installation situation. The bearing support 21 is formed of two parts hereinafter referred to as the first ferrule 22 and the second ferrule 23. The first ferrule 22 more precisely comprises a first annular wall 22a and a first radial fixing flange 22b which extends radially outwards from a radially external surface of the first annular wall 22a. The first ferrule 22 is advantageously made in one piece. The first annular wall 22a carries the external ring of the downstream bearing 20. The internal ring of the bearing 20 cooperates with means mounted on the power shaft. The second ferrule 23 comprises a second annular wall 23a which is mounted on the first ferrule 22a and which extends radially outside the first annular wall 22a.The second annular wall 23a passes at least partly through the internal bore 7 of the disc 5 of the free turbine 3 along the longitudinal axis X. The second annular wall 23a supports a static part of a labyrinth seal which is located between the enclosure 19 and the annular cavity 16.

[0053] With reference to [Fig. 5], the bearing support 21 is fixed to the fixed structure via the rear bearing housing 15. In particular, the first radial flange 22b is intended to be fixed to the second wall 15b of the rear bearing housing 15. For this, the first radial flange 22b comprises a plurality of first holes 24 passing through the wall of the first radial flange 22b on either side along the longitudinal axis X. The first holes 24 are distributed regularly around the longitudinal axis. The second wall of the rear bearing housing 15 also comprises a radial portion 25 in which several blind holes 26 are formed. The blind holes 26 extend along an axis parallel to the longitudinal axis X. These are intended to cooperate with the first holes 24 of the first radial flange 22b. There are as many blind holes 26 as there are first fixing holes 24. First fixing members 27 such as screws, rods and / or bolts, etc.allow the bearing support 21 to be fixed to the housing 15. In the example shown, the first fixing members 27 comprise screws with a head 27a and a rod 27b.

[0054] The first radial flange 22b comprises a first bearing surface 29a which is defined in a radial plane perpendicular to the axis A. The first radial flange 22b also comprises a second bearing surface 29b which is defined in a plane perpendicular to the axis A. The first and second bearing surfaces 29a, 29b are opposite along the axis A.

[0055] The radial portion 25 also comprises a downstream bearing surface 25a which is defined in a plane perpendicular to the longitudinal axis X. The first surface 29a of the first radial 22b is intended to bear against the downstream bearing surface 25a. These create a support-plane connection. In the present example, the first radial flange 22b comprises an annular edge which has an annular surface 22c substantially flush with a radially external surface 25c of the radial portion 25 so as not to disturb the flow of cooling air at the outlet of the cooling device 14.

[0056] [Fig. 3] shows the cover 31. The cover 31 is intended to be mounted on the bearing support 21. The cover 31 is installed in the annular cavity 16 and the cooling air leaving the injectors circulates around it and towards the bore 7. The cover 31 comprises a shape of revolution around an axis B. The axis B is coaxial with the longitudinal axis X in the installation situation. The cover 31 comprises a second radial flange 33 which is intended to be fixed on the first radial flange 22b of the bearing support 21. The fixing of the first radial flange 22b on the second radial flange 33 is carried out by means of the first fixing members 27 (shown in [Fig. 5]). The cover 31 also comprises an annular wall 32 which extends along the axis B and at least partly through the internal bore of the turbine disc.The second radial flange 33 extends radially outward from a radially outer surface 34 of the annular wall 32. The annular wall 32 has an internal diameter which is greater than the external diameter of the second shell (in particular the second annular wall 22a) of the bearing support 21. These first fixing members 27 are distributed regularly around the longitudinal axis X. For this purpose, the second radial flange 33 comprises a plurality of second holes 35 which each pass through the wall of the radial flange 33 on either side along an axis parallel to the longitudinal axis X. The second holes 35 are intended to cooperate with the first holes 24 of the first radial flange 22b. In the installation situation, the first and second holes 24, 35 are coaxial.

[0057] The second radial flange 33 comprises an upstream bearing surface 33a (see [Fig.5]) which is defined in a radial plane perpendicular to the axis B of the cover 31. The upstream bearing surface 33a is intended to come into contact with the second bearing surface 29b of the first flange 22b so as to create a support-plane connection. The second radial flange 33 also comprises an annular edge which has an annular surface 33c substantially flush with the surface 22c of the first flange 22b.

[0058] As shown in [Fig. 3], the cover 31 comprises an annular bearing surface 36 extending radially outwardly and downstream of the second radial flange 33. In particular, the cover 31 comprises a plurality of projections 37 which extend radially outwardly from the radially external surface 34 of the annular wall 32 and which are regularly distributed around the axis of the cover 31. The projections 37 also extend from a downstream surface 33b of the second radial flange 33 along the longitudinal axis X. The downstream surface 33b is axially opposite the upstream bearing surface 33a. The annular bearing surface is formed by the projections 37. The projections 37 are defined by recesses 38 into which the second holes 35 for fixing the second radial flange 33 open. In other words, the projections 37 are arranged alternately with the second holes 35 around the longitudinal axis.The recesses 38 have an orientation substantially parallel to the longitudinal axis and each have a semi-cylindrical section.

[0059] The projections 37 are circumferentially delimited by lateral panels 37a, 37b (which are also the walls of the recesses). These are also each delimited downstream by a downstream surface 39. The latter forms an annular downstream bearing surface of the annular bearing surface 36. The annular downstream bearing surface 39 is defined in a plane which is perpendicular to the longitudinal axis X.

[0060] The turbomachine 1 also comprises a fire-fighting system 30 configured so as to annihilate a fire starting in the cavity 16 or even to eliminate any possibility of ignition in the cavity 16. Indeed, the enclosure 19 with the oil in suspension is close to the cavity 16 which receives cooling air via the cooling device 14. The oil, the cooling air and the heat prevailing in this zone could allow combustion and a fire starting generating a flame in this zone and in the cavity 16 in the event of oil leaking from the enclosure into the cavity. A fire could cause significant damage to the rotor parts, or even the release of high-energy parts.

[0061] When a flame is generated in a cavity 16 exposed to the flow of a mixture of a first fluid (cooling air) and a second combustible fluid (oil), it can be stabilized if the speed of the flame is sufficient to exceed the flow speed of the cooling air in the cavity. The speed of the flame depends on the temperature of the cooling air, the pressure and the concentration of oil.

[0062] The maximum possible flame speed is the turbulent flame speed ST at the maximum pleating ratio. It is assumed that the cooling air / oil mixture is stoichiometric to maximize the laminar flame speed, that there is no heat transfer to the cavity walls to maximize the laminar flame speed and that the pleating ratio is at saturation to maximize the flame wrinkling. Laminar flame speed is a constituent of fuels (gasoline, kerosene, diesel, etc.) that form combustibles.

[0063] In particular, the system 30 comprises holding means configured so as to maintain a speed of the cooling air at the outlet of the injection means and to guide the cooling air through the bore 7 of the turbine disc of the first turbine stage. By maintaining the outlet speed of the cooling air from the injection means it is possible to control and avoid stabilization of the flame generated in the cavity in the event of a fire starting.

[0064] With reference to [Fig. 5], the fire-fighting system 30 comprises a member for adapting the speed of the cooling air leaving the injection means of the cooling device 14. In particular, the adapting member is configured so as to maintain the speed at the outlet of the injectors 17. In the present example, this member is an annular diffuser 52 which also makes it possible to guide the cooling air towards the bore 7 of the disk 5 of the turbine. The adapting member is part of the speed-maintaining means. The annular diffuser 52 is arranged in the annular cavity 16 and extends between the rear bearing housing 15 and the radially inner end 12a. The diffuser 52 installed in the annular cavity divides it into a first cavity 16a and a second cavity 16b.The second cavity 16b is located radially outside the diffuser 52 and is considered a dead cavity since no cooling air can circulate therein. Indeed, the diffuser extends between an upstream edge 54 and a downstream edge 55 along an axis of the diffuser (centered on the longitudinal axis X). The downstream edge 55 is located near the radially internal end 12a of the first flange 12. A clearance J remains between the downstream edge 55 and this radially internal end 12a so as to take into account the thermal expansions of the parts and in particular of the diffuser and the flange 12. Advantageously, the clearance is less than or equal to 1 mm. The upstream edge 54 bears against the rear bearing housing 15. The second cavity 16b is delimited by the flange 12, the platform 13, the structural part 28 and a part of the diffuser 52. The diffuser 52 is provided with channels which are formed in the thickness of an annular wall 53 of the diffuser.The channels are in fluid communication with the injectors 17. The cooling air is mainly guided towards the first cavity 16a which forms a cooling air stream V.

[0065] With reference to Figures 2 and 4, the fire-fighting system 30 further comprises an annular anti-obstruction cover 40 intended to be installed in the first cavity 16a. In particular, the cover 40 is intended to cover the first fixing members 27 in order to prevent the recirculation of air therethrough. The recirculations create turbulence which by nature promotes the catching of flames. The cover 40 makes it possible to avoid the turbulence and to reduce the passage section under the disc and therefore to accelerate the speed of the cooling air. The cover 40 is mounted and fixed in particular on the cover 31. The cover 40 comprises a shape of revolution around an axis C. The axis C is coaxial with the longitudinal axis X of the turbomachine in the installation situation. For this purpose, the first radial flange 22b of the bearing support 21 is mounted on the housing 15 which comprises a portion of the cooling air circuit. The cooling air at the outlet of the injectors 17 is injected in a direction parallel to the longitudinal axis and radially outside the first and second radial flanges 22b, 33 and circulates in the first cavity 16a (flow air stream V) and around the screws.

[0066] The fact of attaching and fixing the cover 40 to the lid 31 makes it possible to reconfigure a portion of the cooling air flow path V between the disc 5 and the cover 40. In this way, the cooling air no longer circulates around the screws (fixing members 27) which are covered by the cover. In particular, the portion of the cooling air flow path V which is reconfigured is delimited at least in part by a radially internal surface 9a of the annular rim 9 and a radially external surface 40a of the cover.

[0067] In [Fig. 4], the cover 40 comprises a bottom wall 41 from which an annular skirt 42 rises. The bottom wall 41 is crossed by a central bore 43 along the axis C of the cover. The central bore 43 defines an internal annular surface 43a. The annular skirt 42 extends along the axis C between the bottom wall 41 and an upstream annular edge 44. The annular wall 32 of the cover 31 is intended to pass through the central bore 43 of the bottom wall 41 of the cover 40. Advantageously, the internal diameter of the annular skirt 42 of the cover 40 is greater than the external diameter of the annular wall of the cover 31 so as to cover the first fixing members 27.

[0068] The annular edge 44 of the cover 40 is located adjacent to a first downstream end of a radially inner wall 53a of the diffuser 52. The channels of the diffuser form the radially inner wall 53a and a radially outer wall 53b. A tiny clearance of a few millimeters (of the order of 5 mm) is provided between the downstream end of the radially inner wall 53a of the diffuser 52 and the annular edge 44 of the cover. The diffuser extends at least partly radially outside a portion of the rear bearing housing, the bearing support, the cover and also the cover. The downstream edge 55 of the diffuser 52 (and carried by the radially outer wall 53b) of the diffuser 52 extends radially outside the cover 31 and downstream of the annular edge 44.

[0069] According to the example shown in [Fig.5], the diameter of the annular skirt 42 varies between the bottom wall 41 and the annular edge 44. In particular, the annular skirt 42 has a decreasing diameter from the annular edge 44 to the bottom wall 4L. annular edge 44 is defined in a radial plane PI which is upstream of a radial plane P2 in which the bearing surface of a screw head 27a of the first fixing members 27 is defined. In other words, the annular edge 44 at least partially overlaps the projections 37 of the cover. This allows the screws to be well covered. The rod 27b connected to the screw head 27a extends through the holes 24, 35 of the flanges 22b, 33. The downstream edge 55 of the diffuser 52 is defined in a plane P which is located downstream of the plane PL. The downstream edge 55 extends radially outside the cover 40 and at a distance from the cover 40. The downstream edge 55 (of a wall portion which extends the radially external wall 53b) covers a portion of the cover 40 so that the cooling air circulates around the cover 40.

[0070] More precisely still and as shown in [Fig.5], the annular skirt 42 comprises a tubular bearing surface 45 which comprises the annular edge 44. The annular skirt 42 also comprises a first frustoconical portion 46 which is connected to the bottom wall 41 and a second frustoconical portion 47 which is arranged between the tubular portion 45 and the first frustoconical portion 46. Alternatively, the annular skirt 42 comprises a single frustoconical portion whose diameter variation is constant.

[0071] With reference to figures 2, 4, 6, 7 and 9, the bottom wall 41 is intended to be fixed on the annular bearing surface 36 of the cover 31 by second fixing members 48. The second fixing members 48 may be screws, rods and / or bolts, etc. For this, the bottom wall 41 comprises a plurality of third holes 49 which pass through the wall on either side along an axis parallel to the axis C. These third holes 49 are intended to cooperate with fourth holes 50 which are arranged in the annular bearing surface 36 of the cover 31 (see figures 3).

[0072] In [Fig. 10], the bottom wall 41 comprises an upstream surface 41a which is defined in a plane perpendicular to the longitudinal axis X. The upstream surface 41a bears against the annular bearing surface (a downstream surface 39) of the cover 31. The fourth holes 50 pass through the wall of the projections 37 on either side along the axis B as illustrated in Figures 5 and 6.

[0073] According to an advantageous characteristic, the bottom wall 41 comprises housings 63 which each open into a third hole 49. Each housing 63 also opens onto a downstream surface 41b of the bottom wall. The downstream surface 41b is opposite the upstream surface 41a along the axis of the cover 40 (longitudinal axis in the installation situation). In the present example, the housing 63 is a recess made in the thickness of the bottom wall 4L. The housings also open onto the internal annular surface 43a of the central bore of the cover 40. Alternatively, the housings are made by counterbores as shown in [Fig. 4]. Here, the second fixing members 48 are advantageously screws each having a head 48a and a rod 48b. Each head 48a is housed and contained in a housing 63. The heads do not protrude from the housing 63 (in particular when the fixing members 48 are mounted in the cover 40 and the lid 31). In other words, the height of each housing 63 along the longitudinal axis is equal to or greater than the height of a head 48a. This makes it possible to avoid recirculation and to obstruct the flow vein V. The number of fixing members 48 is between 4 and 8.

[0074] As illustrated in [Fig. 7], and advantageously, but not limitingly, certain projections 37 comprise the fourth holes 50. In this example, first projections 370 without holes are arranged alternately with second projections 371 provided with holes in the circumferential direction. In other words, every other projection comprises a fourth hole 50.

[0075] Advantageously, the internal annular surface 43a of the central bore of the cover 40 is intended to be in contact (or in support) by complementarity of shape with an annular bearing surface 31a of the cover 31. The annular bearing surface 31a is defined by a shoulder 51 (cf. [Fig.6]) arranged between the annular bearing surface 36 (projections 37) of the cover 31 and the annular wall 32.

[0076] In Figures 8 and 10, the cover 31 and the hood 40 comprise complementary fixing means 60 which are configured so as to axially hold the cover 40 relative to the cover 31. Indeed, the fixing members 48 may be poorly tightened or loosen during operation, which may cause axial movement of the cover towards the disc 5. If the cover 40 (and the screw head 48) comes into contact with the disc 5, the latter risks obstructing the flow vein V, which may cause a loss of cooling of the disc 5. In particular, the cover 40 comprises positioning members which are installed on the radially internal surface of the annular skirt 42. The positioning members are in the form of lugs 61 which extend from the radially internal surface towards the inside of the cover 40. The lugs 61 are regularly distributed around the circumferential direction.The cover comprises receiving elements intended to cooperate with the positioning members. The receiving elements here comprise circumferential grooves. The lugs 61 are intended to cooperate with the circumferential grooves 62 arranged in the cover 31. The lugs 61 and the circumferential grooves 62 constitute the complementary fixing means 60.

[0077] The projections 37 comprise the circumferential grooves 62 extending in a circumferential direction and intended to receive a lug 61. The circumferential grooves 62 are open on each side of the lateral panels 37a, 37b of the projections 37 so as to allow the lugs 61 to slide inside them. In this way, the lugs 61 and the circumferential grooves 62 form a bayonet-type assembly. According to the exemplary embodiment, certain projections 37 are provided with the circumferential grooves. In particular, the first projections 370 having circumferential grooves 62 are devoid of holes 50. The first projections 370 having the circumferential grooves 62 are alternated with second projections 371 having holes 50 in the circumferential direction around the axis B.

[0078] The fire-fighting system has been described in relation to an annular cavity provided upstream of a free turbine disc but may be arranged in a cavity upstream of a disc of a linked turbine in which a flow of cooling air circulates.

[0079] We will now describe the method for mounting the fire-fighting system 30 in the turbomachine. The method comprises a step of providing the sealing system comprising the diffuser 52 and the cover 40. Beforehand, the method comprises a step of positioning and fixing the bearing support 21 in the turbomachine. The method then comprises a step of positioning the cover 31 around the bearing support 21. The cover 31 is positioned so that the first and second holes 24, 35 are opposite each other. In the present example, the sections of the first and second holes are circular. The fixing members 27 are then mounted to fix the radial flange 22b of the bearing support 21 and the radial flange of the cover 31.

[0080] The method comprises a step of fixing the rear bearing housing 15 on the bearing support 21. Advantageously, the cover 31, the bearing support 21 and the housing 15 are fixed with the same fixing members 27.

[0081] The housing 15 is also mounted with the structural part 28.

[0082] The method also comprises a step of placing the cover 40 on the lid 31 as illustrated in [Fig. 7]. The cover 40 is installed so that the bottom wall 41 is in contact with the annular bearing surface 36 (projections 37) of the lid 31. When placing the cover 40, it is oriented so that the lugs 61 are opposite the recesses 38 as shown in [Fig. 8]. The method comprises a step of rotating the cover 40 about the longitudinal axis so as to engage the lugs 61 in the circumferential grooves 62. Following the rotation, the fourth holes 50 of the cover 40 are also positioned so as to be opposite the holes 49 of the lid 31.

[0083] The method further comprises a step of fixing the cover 40 on the lid 31. During this step, the fixing members 48 such as screws are engaged in the holes 49, 50. The screw heads are housed in the housings 63. In this way, in the event of loosening of the fixing members 48, the cover 40 is always held in place thanks to the lugs 61 engaged in the circumferential grooves 62.

[0084] The cooling air leaving the injectors 17 can thus circulate without obstacle in the cooling air flow path V, around the cover 40 and towards the internal bore 7 of the disc. 16

Claims

Claims

1. Fire-fighting system (30) for a turbomachine (1) such as an aircraft turbojet or turboprop, the turbomachine (1) comprising at least one turbine (3) connected to a power shaft of longitudinal axis X and an annular bearing support (21) which is intended to carry at least in part a bearing (20) for guiding the rotation of the power shaft (4) and which comprises a first radial flange (23), the fire-fighting system (30) comprising an annular cover (31) intended to be mounted on the bearing support (21), the cover (31) being intended to be arranged in an annular cavity (16) of the turbomachine in which a cooling air circulates and comprising a second radial flange (33), characterized in that the second radial flange (33) is fixed on a first radial flange (22b) of the bearing support (21) by means of first fixing members (27) distributed regularly around the longitudinal axis X,the system (30) further comprising a cover (40) intended to be fixed on an annular bearing surface (36) of the cover (31) and to cover the first fixing members (27), the cover (40) comprising an annular bottom wall (41) comprising a central bore (43) intended to be crossed by an annular wall (32) of the cover (31) and an annular skirt (42) extending from the bottom wall (41) along the axis C, and in that the bottom wall (41) comprises a plurality of third through holes (49) intended to cooperate with fourth holes (50) formed in the annular bearing surface (36) of the cover (31), the third and fourth holes (49, 50) being intended to receive second fixing members (48) and in that the annular skirt (42) comprises positioning members (61) intended to engage in receiving elements (62) of the cover (31),the positioning members (61) and the receiving element (62) forming complementary fixing means (60) which are configured so as to axially hold the cover (40) on the lid (31).,

2. Fire-fighting system (30) according to the preceding claim, characterized in that the complementary fixing means (60) comprise circumferential grooves (62) which are arranged on the cover (31) and a plurality of lugs (61) which are arranged on the hood (40 and which extend radially towards the axis (C) from an internal surface of the annular skirt (46), the lugs being regularly distributed around the axis of the axle (C) and being intended to engage by sliding in the circumferential grooves (62).

3. Fire-fighting system (30) according to any one of the preceding claims, characterized in that the second fixing members (48) each comprise a head (48a) and in that the bottom wall (41) comprises housings (63) which each open into a third hole (49), each housing (63) being intended to house and contain the head (48a) of the fixing members (48).

4. Fire-fighting system (30) according to any one of the preceding claims, characterized in that the number of second fixing members (48) is between 4 and 8.

5. Fire-fighting system (30) according to any one of claims 3 and 4, characterized in that the central bore (43) is delimited by an internal annular surface (43a) intended to be in contact with an annular bearing surface (31a) of the cover (31) and in that the hood (40) comprises an annular edge (44) which is defined in a plane PI upstream of a plane P2 in which a portion of the bearing surface of the head (48) is defined in the cover (31).

6. Fire-fighting system (30) according to one of the preceding claims, characterized in that the cover (31) comprises a plurality of projections (37) extending radially from a radially outer wall of the cover (31) and comprising the circumferential grooves (62), each circumferential groove (62) extending in a circumferential direction around the axis C and being intended to receive a lug (61).

7. Fire-fighting system (30) according to the preceding claim, characterized in that the projections (37) comprise first projections (370) each comprising a circumferential groove (62) and second projections (371) each comprising a fourth hole (50), the first projections (370) and the second projections (371) being alternated around the axis of the cover (31).

8. Fire-fighting system (30) according to any one of the preceding claims, characterized in that the first radial flange (22b) comprises a plurality of first holes (24) and the second radial flange (33) comprises a plurality of second holes (35) intended to cooperate with each other and to receive the first fixing members (27).

9. Turbomachine (1) in particular of an aircraft, having a longitudinal axis X and comprising a turbine (3) connected to a shaft providing mechanical power on an output shaft, a cavity arranged in upstream of a first stage of the turbine (3), a cooling device (14) intended to supply cooling gas to the annular cavity and a fire-fighting system (30) according to any one of the preceding claims, the fire-fighting system being arranged in the cavity (16).

10. A method of mounting a fire suppression system (30) according to any one of claims 1, 3 to 8 and claim 2, the method comprising the following steps: - placing the cover (40) on the lid (31) so that the bottom wall (41) is in contact with the annular surface (36) of the lid (31), - performing a rotation of the cover (40) around the longitudinal axis so as to engage the lugs (61) in the circumferential grooves (62), - fixing the hood (35) on the cover (31) via the second fixing members (48).

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