Aeronautical turbomachine with ventilated bearing housing

Abstract

The object in question is a bearing housing (12') for a turbomachine, having a volume (121'), delimited between a rotor and a stator, and comprising a duct (250') for primarily evacuating a first fraction of the air-lubricant mixture, in order to degas the internal volume, an oil-cleaning system (37) connected to ambient air, and a recovery duct (230') primarily for the lubricant, and secondarily for a second fraction of said air-lubricant mixture. The lubricant recovery duct (230') communicates with the evacuation duct (250') via a bypass duct (43), in order to evacuate at least part of the second fraction of said air-lubricant mixture, thus allowing for further degassing of the volume (121'). Figure 3 (for the abbreviated version)

Description

Title of the invention: Aeronautical turbomachine with ventilated bearing enclosure Field of disclosure

[0001] The invention relates to the field of aerothermal energy and lubrication, on an aeronautical turbomachine. State of the art

[0002] Conventionally, as shown in [Fig.l], an aeronautical turbomachine 1 comprises from upstream to downstream a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7. The air entering the turbomachine 1 is divided into a primary air flow (arrow A) which circulates in a so-called primary air stream 8 inside successively the low-pressure and high-pressure compressors 3, 4 towards the combustion chamber 5 then through the successively high-pressure and low-pressure turbines 6, 7, and into a secondary air flow (arrows B) which circulates in a so-called secondary air stream 9 bypassing the compressors 3, 4, the combustion chamber 5 and the turbines 6, 7. The streams 8, 9 are crossed by structural arms 10 extending radially.

[0003] Furthermore, an aeronautical turbomachine such as 1 generally comprises bearings, called bearings, which are protected from the other components of the turbomachine by enclosures, called “bearing enclosures” which surround them. Thus, [Fig. 2] schematically represents a bearing enclosure of the prior art linked to a bearing 120. This bearing enclosure 12 makes it possible to isolate from the other parts of the turbomachine the bearing 120 for guiding a tubular shaft 13, of axis X of rotation.

[0004] The bearing 120 comprises: - a fixed external ring 14 mounted on a fixed part 15, or stator, of the turbomachine, - a rotating internal ring 16 mounted on the tubular shaft 13, and - rolling elements 17 interposed, radially to the X axis, between the fixed outer ring 14 and the rotating inner ring 16.

[0005] These three components 14, 16, 17 form moving elements, all or part of which is grouped under the term rotor 18.

[0006] The rotor 18 rotates, around the axis X, relative to a stator 15 located radially around it.

[0007] The stator 15 comprises the fixed outer ring 14, a wall 150 to which the fixed outer ring 14 is fixed and air seals 27.

[0008] In order to ensure the lubrication and cooling of the guide bearing contained in the bearing enclosure 12, it is necessary to inject a lubricant under pressure onto said moving elements 13 and / or 16 and / or 17. For this, the bearing enclosure 12 comprises lubricant injection means 19. These lubricant injection means 19 generally comprise an inlet duct 20 connected to a nozzle 21 which make it possible to send the lubricant under pressure to the rotating ring 16 and / or the rolling elements 17. The bearing enclosure 12 also comprises lubricant recovery means 23 which make it possible to evacuate the used lubricant. Furthermore, in order to ensure the sealing of the bearing enclosure, this bearing enclosure is closed by the air seals 27 bearing radially against the tubular shaft 13.

[0009] A certain air pressure must be ensured in the bearing enclosure 12. For this purpose, air can enter the bearing enclosure at the location of the air seals 27.

[0010] In order to prevent the bearing enclosure 12 from increasing excessively in pressure, the bearing enclosure may also comprise means 25 for evacuating air allowing positive degassing of the bearing enclosure, via a conduit 250 which can pass through the wall 150 of the stator 15. This type of bearing enclosure is typically called a ventilated bearing enclosure. The air evacuated by the conduit of the evacuation means 25 is then charged with a mist of lubricant, therefore oiled air, in other words an air-lubricant mixture, so that it is necessary to purify it, by filtering the lubricant it contains. An oil separator, in other words a de-oiling system into which the evacuation conduit 250 of the air-lubricant mixture opens, capable of separating the lubricant from the air contained in the air-lubricant mixture, is then used.

[0011] It happens in any case that the "oiled air" pressure in the ventilated bearing enclosure is disturbed. Depending on the available margins or the compromises in adjusting the turbomachine, this may result in problems with pressurization and operation of the ventilated bearing enclosure. Disclosure Statement

[0012] To overcome the aforementioned drawback(s) and problem(s), in accordance with the disclosure, it is proposed that, on the aeronautical turbomachine considered, the lubricant recovery means communicate with the aforementioned duct for discharging the air-lubricant mixture via a bypass duct making it possible to evacuate at least a part of a remaining fraction of said air-lubricant mixture, thus ensuring additional degassing of the bearing enclosure.

[0013] More specifically, an aeronautical turbomachine comprising a bearing enclosure is proposed.

[0014] This landing enclosure: - has an internal volume delimited between a rotor mobile in rotation around a reference axis and a stator comprising a bearing support on which is mounted a bearing in support with said rotor, and - includes: — lubricant supply means arranged to supply lubricant to said internal volume, — an air circulation circuit passing through the landing enclosure and comprising: — air supply means arranged to supply air into the internal volume, — a main evacuation duct for an air-lubricant mixture arranged to evacuate, away from the internal volume, mainly at least a first fraction of the air-lubricant mixture contained in said internal volume, thus allowing degassing of the internal volume, — a de-oiling system communicating with the ambient air and connected to the main discharge duct of the air-lubricant mixture, the de-oiling system being capable of separating the lubricant from the air contained in the air-lubricant mixture coming from the discharge duct, — a lubricant reservoir, and — a lubricant recovery conduit arranged to discharge away from said internal volume, towards the lubricant reservoir, mainly at least part of the lubricant having lubricated said bearing and, incidentally, a second fraction of the air-lubricant mixture, the turbomachine being characterized in that the lubricant recovery duct communicates with the main evacuation duct of the air-lubricant mixture by a bypass duct, to evacuate at least a part of the second fraction of said air-lubricant mixture.

[0015] This will allow additional degassing of the internal volume.

[0016] It will be avoided that the “oiled air” pressure in the internal volume of the ventilated bearing enclosure is too high, for example due to insufficient degassing permeability, which may be linked to a sizing problem. Typically, such a situation could arise if the flow of oiled air extracted from the ventilated bearing enclosure to the oil separator becomes insufficient to compensate for the flow of air entering the bearing enclosure, which would cause the pressure in the bearing enclosure to increase.

[0017] With the solution proposed above, the flow of oiled air extracted from the ventilated bearing enclosure to the oil separator is made greater, in a simple and efficient manner.

[0018] Typically, it may be provided that the bearing enclosure further comprises air seals which will close the internal volume, around the rotor, and through which the air supplied by the air supply means may pass to enter said internal volume of the bearing enclosure.

[0019] Thus, the air supply means may be located, in themselves, at a distance from said internal volume and therefore avoid having an air supply duct pass through the wall of the stator surrounding this internal volume “directly” into the internal volume.

[0020] According to another characteristic, it is proposed that the bypass duct has a passage section greater than or equal to the passage section of the lubricant recovery duct.

[0021] Thus, it will be possible to take advantage beyond the oil recovery duct of the passage section of this duct, typically connected to the lower part of said internal volume, to easily transport part of the oiled air to the main degassing provided via the de-oiling system.

[0022] In order to refine the management of the flow rate discharged through the bypass duct and secure the installation, provision may be made to add a means for regulating the flow rate of circulating fluid, mounted on the bypass duct, in order to regulate the flow rate of fluid in the bypass duct.

[0023] An on / off valve may be particularly suitable. A simple and reliable solution.

[0024] The circulating fluid will be an air-lubricant mixture, suitable, if necessary, to be de-oil in the de-oiling system.

[0025] To avoid saturation of the de-oiling system and to encourage reuse of the lubricant resulting from the separation, it may be useful to provide a second lubricant recovery conduit connecting the de-oiling system and the lubricant reservoir, in order to be able to evacuate at least part of the lubricant resulting from said separation between the lubricant and the air to the reservoir. Brief description of the figures

[0026] Other features and advantages of the present disclosure will appear in the following detailed description, referring to the appended drawings in which: [Fig.l] represents a conventional aeronautical turbomachine, in this case a turbojet. [Fig.2] represents a diagram of a bearing enclosure of the prior art, [Fig.3] represents a diagram of a bearing enclosure which may be suitable within the framework of the invention, [Fig.4] represents a diagram of a lubricant evacuation-recovery circuit and an air-lubricant mixture associated with a bearing enclosure in accordance with the invention and therefore with the solution of [Fig.3]. Detailed Description of Disclosure

[0027] Note in the preamble that: - the disclosure is in no way limited to the embodiment described below for illustrative, non-limiting purposes, and - the solution proposed in the present disclosure may in particular use all or part of the aforementioned means presented in connection with known prior art and the common elements of which have been reproduced below, marked with a “'” (prime sign).

[0028] Thus, in the proposed embodiment, the internal volume 121' of the bearing enclosure 12' is delimited, radially to the axis X' around which the rotor 18' rotates, via the bearing 120': - between the rotating tubular shaft 13', the rotating inner ring 16' mounted therein and the rolling elements 17' interposed between the inner 16' and outer 14' rings, and - the stator 15' which comprises the fixed outer ring 14', the wall 150' to which the fixed outer ring 14' are fixed and the air seals 27'.

[0029] An illustration of a possible, or even preferred, embodiment is shown [Fig.3].

[0030] To ensure a supply of lubricant into the internal volume 121' of the enclosure bearing, the injection means 19', the inlet pipe 20' and the nozzle 21' can be combined under the name supply means 22'.

[0031] To ensure, via the air seals 27', the arrival of suitable air in this same internal volume 121', the air can come from air supply or injection means 29 thus allowing pressurized air to be injected into the internal volume 121'.

[0032] This pressurized air can be taken downstream of a compression stage of the turbomachine, and more precisely downstream of the low pressure compressor 3 of the turbomachine.

[0033] The air injection means 29 comprise an air supply duct 290 passing through the wall 150' and which opens into the volume 31 located around the rotating tubular shaft 13', outside the internal volume 121' from which it is separated by the air seals 27'.

[0034] In order to ensure that the injected pressurizing air (see arrows [Fig.3]) passes through the enclosure seals - therefore the air seals 27' - from the outside to the inside of the enclosure, a criterion on the pressure ratio between the external 31 and internal 121' volumes is favorably established.

[0035] The suction effect between the respective pressures PI and P2 (P1>P2) then ensures a sufficient air flow to protect the seal.

[0036] In this way, a suitable pressure can prevail in the internal volume 121'.

[0037] In the case of a ventilated enclosure, it is therefore the pressure difference between the pressures respective PI and P2, therefore between the upstream and downstream of the seal 27', which ensures the correct pressurization of the internal volume 121'.

[0038] For the “air” part, a conduit 250', connecting the volume 121' to the ambient air (Pa) via a de-oiling system 37, defines a “main evacuation conduit”, away from the internal volume 121', mainly of at least a first fraction (largely predominantly air) of the air-lubricant mixture contained in said internal volume 121'.

[0039] To recover lubricant from the internal volume 121', the bearing enclosure 12' comprises a lubricant reservoir 33 and a conduit 230' or means 23' for "main" lubricant recovery, connecting the volume 121' to the reservoir 33.

[0040] The lubricant recovery conduit 230' is in fact arranged to evacuate, away from said internal volume 121': - towards the reservoir 33, mainly at least part (largely majority) of the lubricant having lubricated the bearing 120' and, - incidentally, a second fraction (largely a minority in air) of said air-lubricant mixture.

[0041] Thus, by combining the air evacuations, outside the internal volume 121', mainly via the conduit 250' and to a lesser extent via the conduit 230', it will be possible to promote the degassing of the internal volume 121' and overcome the aforementioned problems.

[0042] The following may thus be considered as belonging to an optimized air circulation circuit 35 passing through the bearing enclosure 12': - the air supply means 29 / 290, - the 250' main evacuation conduit for the air-lubricant mixture present in the internal volume 121', - the de-oiling system 37 connected to the 250' conduit.

[0043] As such, the last two of these three elements can also be considered as belonging to means 25' for the main evacuation of the air-lubricant mixture, outside the volume 121'.

[0044] The de-oiling system 37 may comprise a separation tank 370 which can communicate with the free or ambient air (Pa: atmospheric pressure) via a vent 371.

[0045] At least said first fraction of the air-lubricant mixture therefore separates in the separation tank 370.

[0046] The lubricant, which may be oil, introduced into the bearing enclosure 12' may be recovered from the internal volume 121', by a recovery pump 39 (often positioned around 6 o'clock) mounted on the conduit 230'.

[0047] This conduit 230' and the pump 39 are therefore considered as belonging to the means 23' for recovering the lubricant.

[0048] But, the conduit 250' also belongs to it, taking into account that an accessory quantity of lubricant is evacuated by this “complementary” conduit and can usefully be recovered by a second recovery conduit 41 connecting the de-oiling system, favorably the separation tank 370, and the lubricant reservoir 33, in order to allow a transfer of lubricant from the tank 37 to the reservoir.

[0049] The de-oiling system 37 will thus recover the oil from the oiled air, to reduce oil consumption. The de-oiling system is for example of the cyclonic type, the recovery of the oil from the oiled air is then carried out by centrifugation of the oiled air, which projects most of the oil droplets contained in this air against a peripheral collecting wall of the tank 370.

[0050] The air introduced into the bearing enclosure 12' is thus evacuated through the degassing conduit or tube 250' (generally positioned around midday) towards the oil separator then towards the outside (Pa), after separation.

[0051] To transfer at least a portion of the second fraction of the air-lubricant mixture to the open air (Pa) and thus evacuate it from the internal volume 121', thus allowing additional degassing of this volume, the (main) lubricant recovery conduit 230' communicates via a bypass conduit 43 with the main evacuation conduit 250' of the air-lubricant mixture.

[0052] With such a bypass, engaged on the means 23' for "main" recovery of the lubricant and directed towards the means 25' for "main" degassing opening onto the open air (Pa), it will be useful to manage, in particular to be able to reduce, the pressure in a ventilated enclosure, such as the bearing enclosure 12'.

[0053] Using the (main) lubricant recovery duct 230' to remove the air circulating therein will be all the more relevant if the bypass duct 43 has a passage section greater than or equal to the passage section of the lubricant recovery duct 230'. It is thus even possible to imagine slightly oversizing the section of the bypass duct 43 to favor the pressure ratio.

[0054] Regulating the fluid flow rate in the bypass duct 43 may also make it possible to adapt the functional requirements of the pressure in the internal volume 121' quite finely in relation to more general operation of the turbomachine.

[0055] It is also proposed that a flow control means 45 be mounted on the bypass conduit 43, to control the fluid flow there. The flow control means 45 may in particular comprise an on / off valve 450; this promoting safety against the passage of lubricant in the event of an unexpected problem.

[0056] For comparable purposes, a flow control means 47 may usefully be mounted on said second lubricant recovery conduit 41, to control the flow of lubricant therein. The flow control means 47 may in particular also comprise an on / off valve 470.

Claims

1. Claims Aeronautical turbomachine comprising a bearing enclosure (12') for a turbomachine, said bearing enclosure having an internal volume (121') delimited between a rotor mobile in rotation around a reference axis and a stator comprising a bearing support on which is mounted a bearing (120') bearing with said rotor, the bearing enclosure (1) comprising: - lubricant supply means (22') arranged to supply lubricant to said internal volume (121'), - an air circulation circuit (35) passing through the bearing enclosure and comprising: — air supply means (29,290) arranged to supply air into the internal volume (121'), — a main evacuation duct for an air-lubricant mixture (250') connecting the internal volume (121') to the ambient air (Pa) via a de-oiling system (37) and arranged to evacuate, away from the internal volume, a first fraction of the air-lubricant mixture, including therefore a first part of the lubricant, contained in the internal volume, thus allowing degassing of the internal volume, said de-oiling system (37) communicating with the ambient air (Pa), being connected to the main evacuation duct for the air-lubricant mixture (250') and being capable of separating the lubricant from the air contained in the air-lubricant mixture coming from the main evacuation duct (250'), - a reservoir (33) of lubricant, and - a lubricant recovery conduit (230') arranged to discharge away from the internal volume (121'), towards the lubricant reservoir (33), a second part of the lubricant having lubricated said bearing and incidentally a second fraction of said air-lubricant mixture, the turbomachine being characterized: - in that the first lubricant recovery duct (230') communicates with the main evacuation duct of the air-lubricant mixture (250') by a bypass duct (43), to evacuate therein at least a part of the second fraction of said air-lubricant mixture, and - in that another conduit (41) for recovering the lubricant is further provided, established between the de-oiling system (37) and the reservoir (33) of lubricant, to evacuate, towards the tank, the lubricant resulting from the separation between the lubricant and the air.

2. Aeronautical turbomachine according to claim 1, in which the bearing enclosure (12') further comprises air seals (27') which close the internal volume (121'), around the rotor and through which the air supplied by the air supply means (29,290) can pass to enter said internal volume (121').

3. Aeronautical turbomachine according to claim 1 or 2, in which the bypass duct (43) has a passage section greater than or equal to the passage section of the lubricant recovery duct (230').

4. An aeronautical turbomachine according to one of claims 1 to 3, which further comprises means (45) for regulating a fluid flow rate mounted on the bypass duct (43), for regulating the fluid flow rate in the bypass duct (13).

5. Aeronautical turbomachine according to claim 3, in which the means (45) for regulating the fluid flow rate comprises an on / off valve (450).

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