Accessory housing for an aircraft turbomachine, equipped with internal and external air / oil separators

Abstract

Accessory housing (1) for an aircraft turbomachine, comprising a casing (2) inside which is arranged an internal air / oil separator (3) comprising a centrifugal separation cassette (30) arranged around a hollow shaft (31) driven in rotation by a drive pinion (38), and an external air / oil separator (4) comprising an external enclosure (40) fixed to the outside of the casing and inside which are arranged an air extraction duct (41) having an open inlet end (43) on which is mounted a centrifugal separation dome (45) delimiting an annular channel (46) on which is interposed a filter (47); where the hollow shaft passes through the casing to be coupled in rotation with the centrifugal separation dome and to open into the air extraction duct in order to connect the inside of the hollow shaft with the inside of the air extraction duct.Figure from the summary: Figure 1.

Description

Title of the invention: Accessory housing for an aircraft turbomachine, equipped with internal and external air / oil separators. Technical field

[0001] The invention relates to an accessory housing for an aircraft turbomachine.

[0002] It relates more particularly to an accessory housing equipped with air / oil separation means. Previous technique

[0003] In a known manner, a turbomachine for the propulsion of an aircraft includes an accessory gearbox, designated "AGB" for Accessory Gear Box in English, which incorporates gears, such as toothed wheels or pinions, which are driven in rotation by the turbomachine, generally via a radial drive shaft meshed with a rotating shaft of the turbomachine, in order to take part of the power of the turbomachine to mechanically drive equipment, also called accessories, such as electric generators, oil pumps, fuel pumps, etc., necessary for the operation of the turbomachine or the aircraft.

[0004] In aircraft turbomachinery, air is drawn, generally from an air stream, to circulate through pressurized air labyrinths used to seal rotating assemblies, such as turbines and compressors. This air becomes enriched with oil used for cooling and lubricating the bearings and gears of these rotating assemblies.

[0005] It is also known to use air / oil separators, also called degassers or oil separators, to separate oil from the air before the air is exhausted to the outside, primarily for ecological reasons and also for economic reasons by recovering oil that can be recycled or reinjected into rotating assemblies. Such an air / oil separator thus forms a piece of equipment that can be driven for centrifugal separation by the accessory gearbox.

[0006] It is thus known, for example from document FR3064305, to use an internal air / oil separator, placed inside the accessory housing, and which includes a centrifugal separation cassette arranged around a hollow shaft driven in rotation by a drive pinion in mesh with one of the gears of the accessory housing.

[0007] It is also known, for example from document FR3090394, to use an external air / oil separator, placed outside the accessory housing, and which includes an air extraction duct that delimits an annular volume in an external enclosure around the air extraction duct, a dome centrifugal separation unit mounted on the air extraction duct and defining an annular channel in communication with the annular volume and with the open inlet end of the air extraction duct, and a filter mounted on the centrifugal separation dome and interposed in the annular channel.

[0008] The internal air / oil separator has a small footprint, but it is not suitable for handling excessively high air / oil mixture flow rates, particularly when dealing with air / oil mixtures coming from an engine enclosure.

[0009] The external air / oil separator is suitable for handling high air / oil mixture flow rates. However, such an external air / oil separator requires a main air / oil mixture inlet pipe from the engine compartment, as well as a secondary air / oil mixture inlet pipe from the accessory housing; because the air / oil mixture in the accessory housing must be de-oiled in the same way as that in the engine compartment.

[0010] However, this secondary channel forms an outgrowth on the periphery of the accessory housing, which has a certain diameter which is added to the diameter of the accessory housing casing, thus increasing the radial size of this accessory housing.

[0011] In recent aircraft versions, the accessory box is positioned in the "core" compartment (or central compartment) of the turbomachine, and more particularly around the high-pressure compressor of the turbomachine, where space is more restricted than in the "fan" compartment (or blower compartment).

[0012] There is therefore a need to improve the air / oil separation function (or oil removal function) within a turbomachine, i.e. to be able to handle high air / oil mixture flow rates, while offering a reduced footprint, in other words improved compactness, in particular to allow the accessory housing to be installed in the "core" compartment of the turbomachine, limiting interference with ideal aerodynamic lines. Summary of the invention

[0013] To this end, the invention proposes an accessory housing equipped with an air / oil separation function which has a reduced footprint while being able to handle high air / oil mixture flow rates.

[0014] Thus, the invention proposes an accessory housing for an aircraft turbomachine, comprising a casing inside which is arranged an internal air / oil separator, and further comprising an external air / oil separator comprising an external enclosure fixed to the outside of the casing.

[0015] Thus, this accessory housing includes two air / oil separators, a first one inside the housing of this accessory housing and a second one outside the housing of this accessory housing; it being noted that the accessory housing includes inside this housing gears, generally one or more gear trains, which are driven in rotation by a mechanical take-off by means of a right-angle gearbox on a rotating shaft of the turbomachine.

[0016] The internal air / oil separator comprises a centrifugal separation cassette arranged around a hollow shaft and a drive pinion coupled to the hollow shaft to drive this hollow shaft and this centrifugal separation cassette in rotation.

[0017] The centrifugal separation cassette can thus be fixed to the hollow shaft, and the drive pinion can be fixed around the hollow shaft, for example by means of a connecting flange. This drive pinion meshes with one of the gears of the accessory gearbox, so as to rotate the hollow shaft and the centrifugal separation cassette.

[0018] This centrifugal separator cassette is equipped with inlet ports for the entry of a first air / oil mixture from inside the housing into the interior of said centrifugal separator cassette. Thus, the main function of this internal air / oil separator is to remove oil from the air inside the accessory housing. These inlet ports can be axial ports, provided in a wall of the centrifugal separator cassette or in the connecting web.

[0019] This centrifugal separation cassette is provided with outlet ports to evacuate the oil which is separated from said first air / oil mixture and extracted radially from the centrifugal separation cassette.

[0020] These outlet ports are radial ports, which can be provided on an external peripheral wall of the centrifugal separation cassette, in order to be able to evacuate the oil by the effect of centrifugal force.

[0021] This centrifugal separation cassette is provided with openings made in the hollow shaft and in communication with the interior of the centrifugal separation cassette to evacuate into the interior of the hollow shaft the oil-free air which is separated from said first air / oil mixture.

[0022] Thus, the oil-free air from the first air / oil mixture is evacuated inside the hollow shaft.

[0023] The external air / oil separator comprises an external housing fixed to the outside of the housing. Furthermore, inside the external housing is arranged an air extraction duct that defines an annular volume within the external housing around the air extraction duct. This air extraction duct has an open inlet end and an open outlet end.

[0024] The external air / oil separator comprises a centrifugal separation dome mounted on the open inlet end of the air extraction duct and defining an annular channel in communication with the annular volume and with the open inlet end of the air extraction duct.

[0025] A filter is mounted on the centrifugal separation dome and is interposed in the annular vein.

[0026] The external enclosure has an inlet for injecting a second air / oil mixture into the annular volume, and an oil outlet for evacuating the oil which is separated from said second air / oil mixture and extracted radially from the filter.

[0027] Thus, the second air / oil mixture enters the annular vein of the centrifugal separation dome to pass through the filter, so that the oil-free air continues in the annular vein to reach the inside of the air extraction duct, while the oil is evacuated radially by the effect of the centrifugal force, and can be evacuated through radial holes provided in the centrifugal separation dome on the outer periphery of the filter.

[0028] The external air / oil separator may have a higher processing capacity than the internal air / oil separator, and thus it can process larger flow rates of oiled air. Therefore, the inlet of the second air / oil mixture can be connected to an engine chamber of the turbomachine, so that the second air / oil mixture originates from this engine chamber at a high flow rate, at least higher than that of the first air / oil mixture processed by the internal air / oil separator.

[0029] The inlet of the second air / oil mixture can be provided in the upper part of the external enclosure, while the oil outlet can be provided in the lower part of the external enclosure for a gravity flow of the oil towards this oil outlet.

[0030] The external enclosure has an air outlet in communication with the open outlet end of the air extraction duct to evacuate the oil-free air which is separated from said second air / oil mixture.

[0031] The hollow shaft of the internal air / oil separator passes through the housing to be coupled in rotation with the centrifugal separation cup of the external air / oil separator, and to open into the inside of the air extraction duct in order to connect the inside of the hollow shaft with the inside of the air extraction duct.

[0032] Thus, the hollow shaft of the internal air / oil separator drives the centrifugal separation cup in rotation, so that in the end the drive pinion of the internal air / oil separator drives both the centrifugal separation cassette and the centrifugal separation cup in rotation.

[0033] Furthermore, the oil-free air from the first air / oil mixture passes from the centrifugal separation cassette to the inside of the hollow shaft, then passes from the inside of the hollow shaft towards the inside of the air extraction duct, thus joining the flow of oil-free air from the second air / oil mixture, and thus the oil-free air from the first air / oil mixture and the oil-free air from the second air / oil mixture are evacuated together on the air outlet of the external enclosure.

[0034] Also, there is no need to provide a secondary channel to send the first air / oil mixture from the accessory box to the external air / oil separator, because this first air / oil mixture is treated by the internal air / oil separator; thus helping not to negatively impact the radial dimensions of the accessory box, and therefore to maintain an acceptable level of compactness for a restricted environment, and in particular for an installation of the accessory box in the "core" compartment of the turbomachine.

[0035] According to one feature, the hollow shaft and the centrifugal separating dome have coincident axes of rotation.

[0036] In other words, the hollow shaft and the centrifugal separation dome rotate around the same axis and are therefore coaxial, contributing to an optimized transmission of the rotary torque between the hollow shaft and the centrifugal separation dome.

[0037] According to one possibility, the hollow shaft of the internal air / oil separator has a coupling termination which extends inside the external enclosure of the external air / oil separator, and the centrifugal separation dome is arranged around this coupling termination.

[0038] This coupling termination is open to connect the inside of the hollow shaft with the inside of the air extraction duct.

[0039] According to another possibility, the centrifugal separation dome is fixed on the coupling termination of the hollow shaft.

[0040] According to another possibility, a nut is screwed onto the coupling termination of the hollow shaft to be abutted against the centrifugal separation cup.

[0041] Other means of fixing are of course conceivable for fixing the centrifugal separation dome on this coupling termination of the hollow shaft.

[0042] According to one possibility, the accessory housing includes gears arranged inside the housing to drive at least one piece of equipment, one of the gears being coupled to the drive pinion of the internal air / oil separator to drive in rotation both the hollow shaft, the centrifugal separation cassette and the centrifugal separation dome.

[0043] The invention also relates to an aircraft turbomachine comprising an accessory housing as described above, such as an aircraft turbojet, turboprop or turbomotor (airplane or helicopter).

[0044] The invention also relates to an aircraft comprising such a turbomachine. [Brief description of the figure]

[0045] Other features and advantages of the present invention will become apparent from the following detailed description of a non-limiting example of implementation, made with reference to the accompanying figure in which:

[0046] [Fig-1] is a schematic axial cross-sectional view of an accessory housing according to a example of a project.

[0047] [Detailed description of an embodiment of the invention]

[0048] With reference to [Fig. 1], an accessory housing 1 for an aircraft turbomachine, like a turbojet, a turboprop or an aircraft turboshaft engine, includes a casing 2 delimiting a closed and sealed volume 20, inside of which is arranged an internal air / oil separator 3 and outside of which is mounted an external air / oil separator 4.

[0049] This accessory housing 1 includes gears 5, of the toothed wheel or pinion type, inside the housing 2; only one of these gears 5 is illustrated in [Fig.1].

[0050] The internal air / oil separator 3 comprises a centrifugal separation cassette 30 arranged around a hollow shaft 31 which is rotatably mounted in bearings 32 around a main axis 33.

[0051] This hollow shaft 31 internally delimits an internal channel 34, and the hollow shaft 31 has a first closed end 35 and a second open end 36. The first end 35 is housed inside the housing 2 (i.e., in the volume 20), while the second end 36 is housed outside the housing. The hollow shaft 31 has a coupling termination 37 that extends outside the housing 2 and terminates with the second end 36.

[0052] The centrifugal separation cassette 30 is rotationally fixed to the hollow shaft 31, so that the centrifugal separation cassette 30 rotates with the hollow shaft 31 around the main axis 33.

[0053] The internal air / oil separator 3 includes a drive pinion 38 coupled to the hollow shaft 31, and more specifically connected rigidly to the hollow shaft 31 by a connecting web 39. This drive pinion 38 meshes with one of the gears 5 of the accessory housing 1 to drive the hollow shaft 31 and the centrifugal separation cassette 30 in rotation.

[0054] This centrifugal separation cassette 30 features: - inlet ports for the entry of a first air / oil mixture 81 from inside the crankcase 2 into the inside of the centrifugal separation cassette 30; - outlet ports for evacuating the oil 82 which is separated from said first air / oil mixture 81 and extracted radially from the centrifugal separation cassette 30.

[0055] Openings 310 formed in the hollow shaft 31 are in communication with the interior of the centrifugal separation cassette 30 to discharge into the interior of the hollow shaft 31 (therefore in the internal channel 34) the oil-free air 83 which is separated from the first air / oil mixture 81.

[0056] The external air / oil separator 4 includes an external enclosure 40 fixed to the housing 2 and outside of this housing 2. The external air / oil separator 4 includes an air extraction duct 41 arranged inside the external enclosure 40 and which delimits an annular volume 42 in the external enclosure 4 around the air extraction duct 4L. This air extraction duct 41 has an open inlet end 43 and an open outlet end 44.

[0057] The external air / oil separator 4 comprises a centrifugal separation dome 45 mounted on the open inlet end 43 of the air extraction pipe 41 and delimiting an annular vein 46 in communication with the annular volume 42 (inlet side) and with the open inlet end 43 of the air extraction pipe 41 (outlet side).

[0058] The external air / oil separator 4 includes a filter 47 mounted on the centrifugal separation dome 45 and interposed in the annular vein, and more precisely on the inlet side.

[0059] The external enclosure 40 features: - an inlet 48, in the upper part, to inject a second air / oil mixture 91 inside the annular volume 42; - an oil outlet 49 to evacuate the oil 92 which is separated from the second air / oil mixture 91 and extracted radially from the filter 47; and - an air outlet 50 in communication with the open outlet end 44 of the air extraction duct 41 to evacuate the oil-free air 93 which is separated from the second air / oil mixture 91.

[0060] As described previously, the hollow shaft 31 of the internal air / oil separator 3 passes through the housing 2 so that its coupling end 37 extends inside the external housing 4 of the external air / oil separator 4 to be rotationally coupled with the centrifugal separation dome 45. Thus, it is the hollow shaft 31 that drives the centrifugal separation dome 45 in rotation. The hollow shaft 31 and the centrifugal separation dome 45 have coincident axes of rotation, namely coincident with the main axis 33.

[0061] The centrifugal separation cup 45 can be fixed on the coupling end 37 of the hollow shaft 31, for example by means of a nut 51 screwed onto the coupling end 37 of the hollow shaft 31 to be abutted against the centrifugal separation cup 45.

[0062] Furthermore, the hollow shaft 31 opens into the air extraction duct 41, so that its second end 36 is housed inside this air extraction duct 41, in order to connect the inside of the hollow shaft 31 with the inside of the air extraction duct 41. Thus, the oil-free air flow 83 (separated from the first air / oil mixture 81) joins the oil-free air flow 93 (separated from the second air / oil mixture 91), and these two flows are evacuated at the air outlet 50.

Claims

1. Demands Accessory housing (1) for an aircraft turbomachine, comprising a casing (2) within which is disposed an internal air / oil separator (3) comprising a centrifugal separation cassette (30) arranged around a hollow shaft (31) and a drive pinion (38) coupled to the hollow shaft (31) for rotating said hollow shaft (31) and said centrifugal separation cassette (30), said centrifugal separation cassette (30) being provided with inlet ports for the entry of a first air / oil mixture (81) from the inside of the casing (2) into the inside of said centrifugal separation cassette (30), outlet ports for evacuating the oil (82) which is separated from said first air / oil mixture (81) and extracted radially from the centrifugal separation cassette (30),and openings (310) provided in the hollow shaft (31) and in communication with the interior of the centrifugal separation cassette (30) to evacuate into said hollow shaft (31) the oil-free air (83) which is separated from said first air / oil mixture (81); said accessory housing (1) further comprising an external air / oil separator (4) having an external enclosure (40) fixed to the outside of the housing (2) and within which is arranged an air extraction duct (41) which delimits an annular volume (42) in the external enclosure (40) around said air extraction duct (41) and which has an open inlet end (43) and an open outlet end (44),a centrifugal separation dome (45) mounted on the open inlet end (43) of the air extraction duct (41) and defining an annular channel (46) in communication with the annular volume (42) and with the open inlet end (43) of the air extraction duct (41), a filter (47) mounted on the centrifugal separation dome (45) and interposed in the annular channel (46), the outer enclosure (40) having an inlet (48) for injecting a second air / oil mixture (91) into the annular volume (42), an oil outlet (49) for removing the oil (92) which is separated from said second air / oil mixture (91) and extracted radially from the filter (47), and an air outlet (50) in communication with the open outlet end (44) of the air extraction duct (41) for removing oil-free air (923) which is separated from said second air / oil mixture (91); in which the hollow shaft (31) of the internal air / oil separator (3) passes through the casing (2) to be coupled in rotation with the centrifugal separation cup (45) of the external air / oil separator (4), and to open into the inside of the air extraction duct (41) in order to connect the inside of the hollow shaft (31) with the inside of the air extraction duct (41).

2. Accessory housing (1) according to claim 1, in which the hollow shaft (31) and the centrifugal separating cupola (45) have coincident axes of rotation.

3. Accessory housing (1) according to claim 1 or 2, wherein the hollow shaft (31) of the internal air / oil separator (3) has a coupling termination (37) which extends inside the external enclosure (40) of the external air / oil separator (4), and the centrifugal separation dome (45) is arranged around this coupling termination (37).

4. Accessory housing (1) according to claim 3, in which the centrifugal separation cup (45) is fixed on the coupling termination (37) of the hollow shaft (31).

5. Accessory housing (1) according to claim 4, in which a nut (51) is screwed onto the coupling termination (37) of the hollow shaft (31) to abut against the centrifugal separating cup (45).

6. Accessory housing (1) according to any one of the preceding claims, comprising gears (5) arranged inside the housing (2) to drive at least one piece of equipment, one of the gears (5) being coupled to the drive pinion (38) of the internal air / oil separator (3) to drive in rotation both the hollow shaft (31), the centrifugal separation cassette (30) and the centrifugal separation cup (45).

7. Aircraft turbomachine comprising an accessory housing (1) according to any one of the preceding claims.

8. Aircraft comprising a turbomachine according to the preceding claim.

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