COMPACT ACCESSORY HOUSING WITH INTEGRATED ELECTRIC MACHINE

Description

Technical field of the invention.

[0001] The invention relates to the field of aircraft turbomachinery, and in particular to that of accessory housings equipping such turbomachinery. Technical background

[0002] It is known from prior art, documents US 2009 / 309461 A1, US 2011 / 284328 A1 and US 2015 / 311770 A1.

[0003] An aircraft turbomachine, such as a turbofan, generally comprises a shrouded fan located at the turbomachine's inlet and driven by a low-pressure shaft. In certain high-bypass ratio turbomachine configurations, known as UHBRs (Ultra High Bypass Ratio), a reduction gear can be interposed between the fan and the low-pressure shaft so that the fan rotates at a lower speed than the shaft. This reduced speed also allows for a larger fan, thus achieving high bypass ratios.

[0004] The turbomachine includes an accessory gearbox, known as an AGB (for "Accessory Gear Box"), to power various equipment or accessories necessary for the operation of the turbomachine or aircraft. A typical example of an accessory is a permanent magnet alternator (usually called a PMA, for "Permanent Magnet Alternator"), which generates electrical current, typically using the accessory gearbox. Specifically, the alternator is designed to provide power to the turbomachine's computer, such as the FADEC (Full Authority Digital Engine Control), from idle speed.

[0005] The accessory gearbox consists of a series of gear trains driving the equipment with different speed ratios. The coupling of the accessory gearbox to the turbomachine is conventionally achieved using a radial shaft which is coupled to the rotor of the high-pressure compressor, which drives a transfer shaft coupled to the accessory gearbox via a right-angle gearbox known by the acronym TGB for "Transfer Gear Box".

[0006] Hybrid propulsion is a key area of ​​development aimed at reducing the carbon footprint of air transport. Indeed, combining thermal and electrical energy reduces fuel consumption and therefore CO2 emissions, but also decreases noise pollution and improves propulsion safety in the event of a failure in the thermal part of the turbomachine.

[0007] The application of hybridization is likely to take different forms on aircraft, but generally requires the integration of more and more electrical equipment into accessory boxes, and in particular not only alternators but also electric machines capable of providing motive power.

[0008] This need for new equipment poses problems in terms of the size of accessory gearboxes, because the equipment mounted on an accessory gearbox is generally attached to its housing on two parallel, essentially flat, opposing side walls, between which shafts carrying each of the gear trains are mounted. Consequently, the addition of new external equipment, such as an electric motor, increases the size, particularly the axial size, of the accessory gearbox. This increase in size is all the more detrimental given that current trends in accessory gearbox placement aim to position them in the central area of ​​the turbomachine, where space is limited, rather than near the fan.The compactness of accessory housings and their equipment is therefore becoming a priority, and it is therefore desirable to increasingly integrate the equipment inside the accessory housing casing.

[0009] An electrical machine is, in particular, a rather bulky piece of equipment. As a reminder, an electrical machine is an electromechanical device based on electromagnetism that converts electrical energy, for example, into mechanical energy (motor mode) or, conversely, produces electricity from mechanical energy (generator mode). The electrical machine can switch from generator mode to motor mode, and vice versa, depending on how it is controlled.

[0010] Document FR-2 897 895 A1 proposes the integration of a starter-generator type electric machine, constructed in two parts, within an accessory housing. The housing of this housing is modified to accommodate, on either side of a pinion, a synchronous generator with a rotor acting as the field winding and a stator acting as the armature, and on the other side, an exciter with a stator acting as the field winding and a rotor acting as the armature connected to the generator's field winding. This configuration of the starter-generator eliminates the possibility of flat side walls in the accessory housing and significantly increases its axial dimensions. Furthermore, separating the starter-generator into two parts, each positioned on either side of the pinion, considerably increases the complexity of the accessory housing assembly.

[0011] Currently, there is no accessory housing available for a compact electric machine. Such equipment is not fully integrated into the AGB. Therefore, there is a genuine need for a compactly integrated electric machine for the AGB. Summary of the invention

[0012] The invention proposes to satisfy this need by offering an accessory case that takes advantage of an internal volume to house an electrical machine.

[0013] To this end, the invention proposes an accessory housing for an aircraft turbomachine, said housing comprising a casing defining an enclosure which houses at least one gear train comprising a series of pinions, the casing comprising two parallel, flat, and opposed side walls between which are mounted shafts carrying each of the pinions of the gear train, said side walls of the casing receiving each of the accessories, each comprising a shaft passing through one of the walls and coupled with the shaft carrying one of the gears of the gear train, and one of the side walls being adapted to be passed through by a transfer shaft of a power transmission device of the turbomachine which is coupled with a shaft carrying one of the gears of the gear train, the side walls of the casing delimiting within the enclosure, an internal volume which surrounds a shaft carrying at least one gear called the hybridization gear, said shaft being surrounded by an electric machine within the casing, said machine comprising at least a rotor and a stator, the rotor of the electric machine being carried by the shaft carrying the hybridization gear of the gear train and the stator, extending around said rotor, is mounted within the enclosure in said internal volume,characterized in that said rotor comprises a face that abuts against a portion of the hybridization pinion.

[0014] The accessory housing according to the invention conventionally has two flat, parallel side walls, and the electrical machine is housed between these walls. It therefore has no protrusions that could compromise its compactness.

[0015] According to other case characteristics: The hybridization pinion shaft is mounted to rotate within the housing between two bearings, each supported by one of the side walls. It comprises a first section receiving the hybridization pinion, arranged near one of said bearings, and a second section extending between said hybridization pinion and a second opposite bearing. The rotor is fixed to said second section. The second section of the shaft is integral with the first section. The hybridization pinion has a web with a diameter greater than the second section of the hybridization pinion shaft and carries on its outer periphery a meshing tooth. The rotor extends axially from said web towards the second bearing. An external bearing surface of the rotor, arranged recessed from a free end of the shaft, receives an inner ring of the bearing. Rotational connecting means are interposed between an internal bore of the rotor and the second section of the hybridization pinion shaft.The hybrid pinion comprises a tubular section extending from its web to the adjacent side wall and having at its end a first end flange receiving at least one inner ring of one of the bearings; the shaft carrying the hybrid pinion is tubular and has a bore coaxial with an orifice formed in one of the adjacent side walls, said bore having internal splines for coupling with a shaft of one of the accessories fixed to said adjacent wall; the hybrid pinion is an intermediate pinion of the gear train; an external face of one of the side walls carries a tubular sleeve adapted to surround and be traversed by the transfer shaft, and it includes an additional electrical machine mounted inside said sleeve.A stator of the auxiliary electric machine is fixed in the sleeve and a rotor of the auxiliary electric machine is fixed to the transfer shaft, the stator of the auxiliary machine being mounted around the rotor of the auxiliary electric machine.

[0016] The invention also relates to an aircraft turbomachine comprising a power transmission device including: a substantially radial drive shaft mounted rotationally fixed to a main shaft of said turbomachine, a right-angle gearbox coupled to said drive shaft, a transfer shaft coupled to said right-angle gearbox, characterized in that it comprises an accessory housing of the type described above which is coupled to said transfer shaft. Brief description of the figures

[0017] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the attached drawings in which: [ Fig. 1 ] There figure 1 is a schematic cross-sectional view of a turbomachine including an accessory housing, [ Fig. 2 ] There figure 2 is a schematic cross-sectional view of an accessory housing according to a prior art; [ Fig. 3 ] There figure 3 is a schematic cross-sectional view of an accessory housing according to the invention; [ Fig. 4 ] There figure 4 is a cross-sectional view of the electrical machine's placement around the axis of the hybridization pinion; [ Fig. 5 ] There figure 5 is a schematic cross-sectional view of the installation of an additional electrical machine in a sleeve surrounding a transfer shaft coupled to the accessory gearbox. Fig. 6 ] There figure 6is a cutaway perspective view of the electrical machine's placement in the sheath surrounding the transfer shaft coupled to the accessory housing. Detailed description of the invention

[0018] We represented at the figure 1 The invention applies to a turbomachine 10 with longitudinal axis X. The turbomachine 10 shown is a twin-spool, twin-flow turbomachine intended for mounting on an aircraft. Of course, the invention is not limited to this type of turbomachine.

[0019] In this application, the terms "upstream", "downstream", "axial" and "axially" are defined with respect to the direction of gas flow in the turbomachine and also along the longitudinal axis, and even from left to right on the figure 1 The terms "radial", "radially", "internal" and "external" are also defined with respect to a radial axis Z that is perpendicular to the X axis of the turbomachine.

[0020] This twin-spool, twin-flow turbomachine 10 comprises a fan 12 mounted upstream of a gas generator or gas turbine engine 14. The fan 12 comprises a plurality of fan blades 16 extending radially from the periphery of a disk 18 through which a fan shaft 20 passes. The fan 12 is surrounded by a fan casing 22 centered on the longitudinal axis X. The fan casing 22 is supported by a nacelle 24 extending around the gas generator 14 along the longitudinal axis X.

[0021] The gas generator 14 comprises, from upstream to downstream, a low-pressure (LP) compressor 26, a high-pressure (HP) compressor 28, a combustion chamber 30, a high-pressure turbine 32, and a low-pressure turbine 34. The rotor of the HP compressor 28 is connected to the rotor of the turbine 32 via an HP shaft 36 centered on the longitudinal axis to form a first, so-called high-pressure section. The rotor of the LP compressor is connected to the rotor of the LP turbine via an LP shaft 38 centered on the longitudinal axis to form a second, so-called low-pressure section. The LP shaft 38 extends inside the HP shaft 36. The HP shaft 36 is a drive shaft, which is rotated about the longitudinal axis X within an internal housing 40 centered on the longitudinal axis.

[0022] An airflow F entering the turbomachine via the fan 12 is split by a turbomachine separation nozzle 42 into a primary airflow P, which passes through the gas generator 3 and specifically into a primary stream, and a secondary airflow S, which circulates around the gas generator 14 in a secondary stream 42. The primary stream 44 and the secondary stream 42 are coaxial. The secondary airflow S is ejected by a secondary nozzle 46 terminating the nacelle 24, while the primary airflow P is ejected outside the turbomachine via an ejection nozzle 48 located downstream of the gas generator. The primary vein 44 is delimited at least in part, radially, by the inner casing 40 and by an inlet casing 50. The secondary vein 42 is delimited at least in part, radially, by the inlet casing 50 and by the blower casing.The inlet housing 50 carries the separation nozzle 42 upstream and is extended downstream by an inter-vein housing 52 which carries the ejection nozzle 48.

[0023] In an optional configuration, a speed reducer 54 can connect the BP shaft 38 to the blower shaft 20, allowing the speed of the blower 12 to be reduced to a speed lower than that of the BP shaft 38. The speed reducer 54 also allows for the arrangement of a blower 12 with a large diameter in order to increase the dilution ratio. The dilution ratio of the blower 12 is advantageously greater than 10. Preferably, the dilution ratio is between 15 and 20. The speed reducer can be a planetary or epicyclic type.

[0024] The turbomachine 10 includes a substantially radial drive shaft 56 which is connected on one side to the high-pressure shaft 36, forming the main shaft of the turbomachine, and on the other side to an accessory gearbox 58 of the turbomachine. The drive shaft 56 extends substantially radially, that is, at an angle between 0° and 30° with respect to the radial axis Z, or between 60° and 90° with respect to the longitudinal axis X. This drive shaft drives the motor shaft, in this case the high-pressure shaft 36, to rotate in order to start the turbomachine via equipment or an accessory cooperating with the accessory gearbox, which will be described below.

[0025] In this example, the drive shaft 56 is called a radial shaft because it extends substantially radially, being housed within a structural element of the turbomachine. This structural element extends substantially radially between the inner casing 40 and the fan casing and / or the nacelle 24. The structural element is a casing arm 60 that structurally connects the inner casing 40 to the fan casing. At its end, the drive shaft 56 is received in a right-angle gearbox 62 in which it is meshed with a transfer shaft 64, whose axis A is substantially parallel to the X-axis, which is itself coupled to the accessory gearbox 58.

[0026] The accessory case 58 is arranged in a compartment of the nacelle 24. The figure 2 represents an accessory housing 58 known from the prior art, which receives various equipment or accessories of the turbomachine.

[0027] These devices, mounted on the 58 housing, can be fuel pumps, electric generators, a lubrication unit, a starter, hydraulic pumps, etc.

[0028] The housing 58 conventionally comprises a casing 66 defining an enclosure 68 housing here at least one gear train comprising a series of pinions, and more particularly here two gear trains 70 and 72. The casing 58 comprising two parallel substantially flat lateral walls 74 and 76 opposed between which are mounted shafts carrying each of the pinions of the gear train.

[0029] The transfer tree 64, which was partially represented on the figure 2, draws or supplies mechanical power to the HP shaft 36. The transfer shaft 64 is coupled to the two gear trains 70, 72. The two gear trains 70, 72 thus described function to drive in rotation a plurality of separate accessories fixed to the walls 74, 76. For example, without limiting the invention, these accessories include two electric generators 78, 80 for supplying electrical power to the aircraft, an electric machine 82 for starting the engine or generating an electric current, an electric generator 84 for supplying electric current to other engine equipment such as two hydraulic pumps 86, 88 for supplying pressurized oil to the engine and / or its equipment, a main oil pump 90 for supplying lubricating oil to the oil circuits of the engine and / or its equipment, a main fuel pump 92, and an oil separator centrifugal 94, which is a passive component.

[0030] Of course, it will be understood that this provision is provided only as an example and is not limiting to the invention and that an accessory case 58 according to the invention may include a different number of accessories.

[0031] The side walls 74, 76 therefore receive these accessories 78, 80, 82, 84, 86, 88, 90, 92, each of which has a corresponding shaft passing through one of the walls 74, 76 and which is coupled with a corresponding carrier shaft 78a, 80a, 82a, 84a, 86a, 88a, 90a, 92a of one of the pinions 78b, 80b, 82b, 84b, 86b, 88b, 90b, 92b of one of the gear trains 70 or 72. The side wall 76 is traversed by the transfer shaft 64 which is coupled with the carrier shaft 84 of the pinion 84b of the gear train 70.

[0032] As illustrated by the figure 2The side walls 74, 76 delimit within the enclosure 68 at least one internal volume 96, represented here in dotted lines, which surrounds a shaft 82a carrying a pinion 82b. This internal volume 96 is arranged on one side of the pinion 82b.

[0033] In the context of the hybridization of the accessory housing 58, the invention proposes to take advantage of such an internal volume 96 in an accessory housing 58 to house an electric machine 82. For this purpose, the electric machine surrounds the carrier shaft 82a and the pinion 82b is called the hybridization pinion.

[0034] This configuration has been schematically represented in the figure 3 .

[0035] As before, the housing 58 receives an electric machine 82 comprising a rotor 82c and a stator 82d. However, unlike a housing 58 known from the prior art, the electric machine 82 is housed in the internal volume 96.

[0036] More specifically, the rotor 82c of the electric machine 82 is carried by the carrier shaft 82a of the hybridization pinion 82b of the gear train 70 and the stator 82d extends around said rotor 82c and is mounted within the enclosure 68 in said internal volume 96.

[0037] In the configuration shown here, the hybridization pinion 82b is an intermediate pinion of the gear train 70, but it will be understood that this arrangement is not limiting of the invention.

[0038] This configuration is particularly advantageous because it allows for an electric machine 82 that is no longer fixed to the side wall 74 but is integrated into the housing 66. Consequently, it allows for a reduction in the axial dimensions of the housing 58 along axis A in the axis of the pinion 82b of the gear train 70. This configuration allows for a less axially bulky housing 70, which is particularly advantageous when the housing needs to be positioned near the central area of ​​the turbomachine.

[0039] Alternatively, (not shown), integrating the electric machine 82 inside the housing 66 frees up the space previously used on the side face 74 to position another accessory, thus reducing the transverse footprint of the housing 58.

[0040] Another advantage of such an arrangement is that, due to its positioning in the casing 66, the electric machine 82 can benefit from the internal lubrication of the casing 66, which is necessarily already present due to the presence of the gear trains 70, 72.

[0041] There figure 4 illustrates in a non-limiting manner of the invention an example of mounting such an electrical machine 82.

[0042] As can be seen, the shaft 82a of the hybridization pinion 82b is mounted to rotate within the housing 66 between two bearings 98, 100, each supported by one of the side walls 74, 76. The shaft 82a has a first section 82a1, which includes the hybridization pinion 82b, and which is positioned near one of said bearings, namely bearing 98. It has a second section 82a2, which extends between the hybridization pinion 82b and the opposite second bearing 100. The rotor 82c is fixed to the second section 82a2.

[0043] In the example shown here, the second section 82a2 of the shaft 82a is a single piece with the first section 82a1. The hybrid pinion 82b is therefore also a single piece with the shaft 82a.

[0044] The hybridization pinion 82b has a web 82b1 which has a diameter greater than the second section 82a2 of the shaft 82a of the hybridization pinion 82b and which carries on its outer periphery a meshing tooth 82b2. A first face 82c1 of the rotor 82c is received against this web 82b1, and the rotor 82c extends substantially axially from said web 82b1 towards the bearing 100, and more particularly along a part of the second section 82a2 to an outer bearing surface 82c2 of the rotor 82c which is arranged recessed from a free end 82a4 of the shaft 82a and which receives an inner ring 100a of the bearing 100.

[0045] Therefore, the hybridization pinion 82b, the shaft 82a, and the rotor 82c can be assembled simply by sliding the rotor 82c directly onto the shaft 82a, butting it against the web 82b1 of the hybridization pinion 82b. Then, the bearing 100 is mounted on the rotor 82c, thus axially immobilizing the rotor 82c between the bearing 100 and the web 82b1 of the pinion 82b.

[0046] It will be understood that means of rotational connection will be interposed between an internal bore 82c3 of the rotor 82c and the second section 82a2 of the shaft of the determined pinion 82b.

[0047] On the side of the hybridization pinion 82b, it includes a tubular section 82b3 which extends from its web 82b1 towards the adjacent side wall 76 and which has at its end a first end collar 82b4 receiving at least one inner ring 98a of the bearing 98.

[0048] The shaft 82a of the hybridization pinion 82b can be solid, but preferably, as illustrated by the figure 4 , it is tubular and it has a bore 82a6 which is coaxial with an orifice 101 formed in one of the adjacent side walls, here wall 74, said bore having internal splines 82a7 for coupling with a shaft of one of the accessories (not shown) fixed to the adjacent wall 74.

[0049] THE Figures 5 And 6 illustrate an optional configuration of the housing 58 comprising an additional electric machine 83. As illustrated by the figure 5An external face 76b of one of the side walls, here wall 76, carries a tubular sleeve 102 which is adapted to surround and be traversed by the transfer shaft 64. The sleeve 102 includes an additional electric machine 83 which is mounted inside said sleeve 102. A stator 83d of the additional electric machine 82 is fixed in the sleeve 102 and a rotor 83c of the electric machine is fixed to the transfer shaft 64. The stator 83d of the additional electric machine 83 is, of course, mounted around the rotor 83c of the additional electric machine.

[0050] As can be seen on the figure 6The sleeve 102 is fixed to the side wall 76 of the accessory housing. It is also received in a tubular sleeve 63 of the angle drive device in a sliding manner, so as to absorb the functional clearances of the angle drive device 62 and the transfer shaft 64 when the angle drive device 62 is coupled to the housing 58 and to absorb the clearances resulting from the expansion of these parts in operation.

[0051] The assembly is therefore simplified since during assembly it is sufficient to fix the sleeve 102 equipped with the stator 83d to the accessory housing 58, then to fix the rotor 83c to the transfer shaft 64 and finally to insert the transfer shaft 64 equipped with its rotor 83c into the sleeve 102.

[0052] The invention therefore makes it possible to benefit from a turbomachine whose hybridization is carried out internally in the accessory housing, with a housing 58 that can be housed compactly near the central area of ​​the turbomachine.

Claims

1. An accessory gearbox (58) for an aircraft turbomachine (10), said gearbox (58) comprising a casing (66) defining an enclosure (68) which houses at least one gear train (70, 72) comprising a series of pinions (78b, 80b, 82b, 84b, 86b, 88b, 94b), the casing (68) comprising two flat and opposite parallel side walls(74, 76) between which are mounted shafts (78a, 80a, 82a, 84a, 86a, 88a, 94a) supporting each of the pinions (78b, 80b, 82b, 84b, 86b, 88b, 94b) of the gear train (70, 72), said side walls (74, 76) of the casing (68) each receiving accessories (78, 80, 82, 84, 86, 88, 90, 92, 94) which each comprise a shaft passing through one of the walls (74, 76) and which is coupled to the shaft (78a, 80a, 82a, 84a, 86a, 88a, 94a) supporting one of the pinions (78b, 80b, 82b, 84b, 86b, 88b, 94b) of the gear train (70, 72), and one of the side walls (76) being able to be passed through by a transfer shaft (64) of a power transmission device of the turbomachine which is coupled to a shaft (84a) supporting one of the pinions (84b) of the gear train, the side walls (74, 76) of the casing (68) delimiting in the enclosure (68) an internal volume (96) which surrounds a shaft (82a) supporting at least one pinion, referred to as a hybridisation pinion (82b), said shaft being intended to be surrounded by an electric machine (82) in the gearbox (58), said machine comprising at least one rotor (82c) and one stator (82d), the rotor (82c) of the electric machine (82) being supported by the shaft (82a) supporting the hybridisation pinion (82b) of the gear train (70) and the stator (82d), extending around said rotor (82c), is mounted within the enclosure (68) in said internal volume (96), characterised in that said rotor (82c) comprises a face (82c1) coming into abutment on a portion of the hybridisation pinion (82b).

2. The gearbox (58) according to the preceding claim, characterised in that the shaft (82a) of the hybridisation pinion (82b) is mounted so as to rotate in the casing (66) between two bearings (98, 100) each supported by one of the side walls (74, 76) and in that it comprises a first section (82a1) comprising the hybridisation pinion (82b), arranged close to a first (98) of said bearings, and a second section (82a2) which extends between said hybridisation pinion (82b) and a second opposite bearing (100), the rotor (82c) being secured to said second section (82a2).

3. The gearbox (58) according to the preceding claim, characterised in that the second section (82a2) of the shaft (82a) is in one piece with the first section (82a1).

4. The gearbox (58) according to one of claims 2 or 3, characterized in that the hybridisation pinion (82b) comprises a web (82b1) which has a diameter greater than the second section (82a2) of the shaft (82a) of the hybridisation pinion (82b) and which supports, at its external periphery, meshing toothing (82b2), and in that the rotor (82c) extends axially from said web (82b1) towards the second bearing (100), an outer surface (82c2) of the rotor (82c) arranged in a recess from a free end (82a4) of the shaft (82a) receiving an inner ring (100a) of the bearing (100).

5. The gearbox (58) according to the preceding claim, characterised in that rotational connection means are interposed between an internal bore (82c3) of the rotor (82c) and the second section (82a2) of the shaft (82a) of the hybridisation pinion (82b).

6. The gearbox (58) according to one of claims 4 or 5, characterised in that the hybridisation pinion (82b) comprises, at the free end of the first section (82a1) of the shaft (82a), a first end collar (82b4) receiving at least one inner ring (98a) of one of the bearings (98).

7. The gearbox (58) according to one of the preceding claims, characterised in that the shaft (82a) supporting the hybridisation pinion (82) is tubular and in that it comprises a bore (82a6) which is coaxial with an orifice (101) formed in one of the adjacent side walls (74), said bore (82a6) comprising internal splines (82a7) for coupling with a shaft of one of the accessories secured to said adjacent wall (74).

8. The gearbox (58) according to one of the preceding claims, characterised in that an external face (76b) of one of the side walls (76) supports a tubular sheath (102) which is able to surround and be passed through by the transfer shaft (64), and in that it comprises an additional electric machine (83) which is mounted inside said sheath (102).

9. The gearbox (58) according to the preceding claim, characterised in that a stator (83d) of the additional electric machine (83) is secured to the sheath (102) and in that a rotor (83c) of the additional electric machine (83) is secured to the transfer shaft (64), the stator (83d) of the additional electric machine (83) being mounted around the rotor (83c) of the additional electric machine (83).

10. An aircraft turbomachine (10) comprising a power transmission device comprising: - a substantially radial drive shaft (56) securely mounted to rotate with a main shaft of said turbomachine, - a transfer gearbox (62) coupled to said drive shaft (56), - a transfer shaft (64) coupled to said transfer gearbox (62), characterised in that it comprises an accessory gearbox (58) according to one of the preceding claims which is coupled to said transfer shaft (64).