ELECTRIC FAN FOR AIRCRAFT

Abstract

The invention relates to a fan comprising: - a housing (1), - a body (2) defining with the housing a flow channel (V) for an airflow (F1, F2), the body comprising an upstream cone (22), a central portion (24) and a downstream cone (26), the downstream cone comprising at least one first orifice, - a shaft (3), - a fan wheel (4), - an electric motor (5), - a first air bearing (6) located upstream of the electric motor and supported by the upstream cone (22), - a second air bearing (7) located downstream of the electric motor, and - several air passages (P1, P2, P3, P4) are provided inside said body to convey said airflow from said first orifice to the upstream cone (22), this upstream cone comprising second orifices (280) for the passage of this air. Figure for the abstract: Figure 5

Description

Title of the invention: ELECTRIC FAN FOR AIRCRAFT Technical field of the invention

[0001] The present invention relates to an electric fan. The invention also relates to an aircraft comprising such an electric fan. Technical background

[0002] It is known to use electric fans on board various types of aircraft, and in particular on board airplanes.

[0003] These fans are known for cooling various on-board equipment such as, for example, on-board computers or other devices fitted to aircraft. Other on-board fans contribute, for example, to the recirculation of air in the aircraft cabin. Generally, the fan comprises an electric motor and a ventilation wheel secured to a rotating part (namely a shaft line) of the electric motor. The fan shaft is supported by guide bearings. These bearings are conventionally ball bearings and ensure the rotation of the fan shaft. These ball bearings are preferably greased for life to, on the one hand, avoid lubricating the bearings with oil and having to manage a dedicated lubrication circuit, and on the other hand, avoid finding oil particles in the ventilation circuit.The disadvantage of these ball bearings is their limited rotation speed due to the presence of grease. Ball bearings can generally be used for a fan rotating at a maximum speed of 24,000 rpm, beyond which friction on the bearings can impact their lifespan.

[0004] Another challenge in the field of electric fans for aeronautics is to significantly reduce their weight. For a given performance of the fan, the higher the rotation speed of the ventilation wheel, the more its diameter will tend to be reduced. Thus, the mass of the wheel will be reduced, just as the mass of the other components surrounding the wheel can also be reduced, such as the electric motor and its casing. However, as described above, increasing the rotation speed beyond 24,000 rpm is not possible with rolling bearings regardless of their lubrication method.

[0005] To overcome these drawbacks, another guide bearing technology is integrated on the fan shaft. More particularly, air guide bearings (more specifically leaf bearings) can be integrated on the shaft. These air bearings include flexible leaves and corrugated leaves positioned around the fan shaft. fan to create stiffness and damping necessary to support the shaft once a minimum speed limit is reached. In fact, below a first value of shaft rotation speed (for example, around 3,000 rpm), there is dry contact between the bearing leaves and the shaft. During this period of contact, there will be wear on the bearings. Above a second value of rotation speed (for example, around 10,000 rpm), the bearing leaves detach from the shaft. There will be no more contact between the bearing leaves and the shaft, and therefore no more wear on the air bearing. Between the first and second speeds, friction will be reduced, with slight rubbing and take-off / landing phases of the shaft line on the bearings.

[0006] Even if this fan configuration with the air bearings makes it possible to reduce or even eliminate wear on the air bearings during operation, it nevertheless poses some difficulties, and in particular pressure losses due to the shearing of the air between the bearing sheets and the shaft. These losses can generate an accumulation of calories and thermal heating which can damage the air bearings.

[0007] In this context, it is interesting to overcome the drawbacks of the prior art, by proposing an electric fan for an aircraft that is reliable and has an improved lifespan. Summary of the invention

[0008] The invention relates to an electric fan for an aircraft, comprising: - a tubular casing extending along and around a longitudinal axis X, - a body extending along the X axis and inside said casing, the body and the casing defining between them an annular flow path for an air stream, the body comprising an upstream cone, a central portion and a downstream cone, the downstream cone comprising at least a first orifice for the passage of air from said flow path inside said body, - a shaft extending along the X axis and inside the body, - a ventilation wheel carried by a first longitudinal end of the shaft, - an electric motor mounted inside the body and around the shaft, - a first air bearing guiding the shaft located upstream of the electric motor and carried by the upstream cone, - a first axial annular stop connected to said central portion, - a second air bearing for guiding the shaft located downstream of the electric motor and carried by said first axial stop, - a second axial annular stop connected to the downstream cone, and - an axial annular thrust disc carried by a second longitudinal end of the shaft opposite said first longitudinal end of the shaft.

[0009] According to the invention, several air passages are provided inside said body for conveying said air flow from said first orifice to the upstream cone of the first air bearing, this upstream cone comprising second orifices for the passage of this air.

[0010] Such a configuration of the fan makes it possible to effectively cool all of the bearings upstream and downstream of the electric motor by a single air flow circulation from downstream to upstream of the fan body. Indeed, the rotation of the ventilation wheel generates an air flow having a first pressure F1 at the outlet of the wheel which is greater than a second pressure F2 of the same air flow (located at a distance from the wheel) due to the pressure losses which are present in the annular vein (for example by the presence of holes in the fan, the friction of air against the walls of the fan and / or the presence of rectifiers). Thus, a depression is created in the annular air passage vein of the fan.The integration of the first and second orifices, respectively, on the upstream and downstream cone of the body, and the plurality of air passages inside the body, as well as the presence of this depression allow the passage of the air flow coming from the annular vein inside the body of the fan. This promotes the cooling of the air bearings and in particular the air thrust bearings of the fan. For this, a cooling (or ventilation) circuit can be formed by the first and second orifices and the air passages which are preferentially located between the shaft and the components (such as the radial bearings, the electric motor, the axial thrust bearings, etc.) surrounding this shaft inside the body. Thus, the cooling circuit makes it possible to ventilate the air bearings and prevent an accumulation of calories leading to thermal runaway.Therefore, the life of the air bearings (and therefore the fan) is significantly improved.

[0011] Furthermore, the integration of the orifices and air passages of the fan according to the invention also makes it possible to reduce the mass and size of the fan in an aircraft.

[0012] The fan according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0013] — the first guide air bearing is radial (in particular with respect to the X axis);

[0014] — the second guide air bearing is radial (in particular with respect to the X axis);

[0015] — the second guide air bearing is radial and axially thrust;

[0016] — the first axial annular stop comprises at least one smooth sheet and at least a wavy sheet;

[0017] — the second axial annular stop comprises at least one smooth sheet and at least a wavy sheet;

[0018] - the fan comprises: - a first air passage connecting said first orifice to the second air bearing, - a second air passage connecting the first air passage to the electric motor, - a third air passage connecting the second air passage to the first air bearing, and - a fourth air passage connecting the third air passage to the second orifices;

[0019] - said second air passage orifices are formed in a transverse wall of the upstream cone which is connected to the central portion of the body;

[0020] - the axial annular thrust disc is interposed between the first and second thrust bearings axial annular;

[0021] - said second air bearing and said first axial annular thrust bearing are formed of a single piece;

[0022] — the air passages are formed by openings in the fan elements and / or gaps between fan elements;

[0023] — the first axial annular stop comprises a radial annular wall extending around the X axis;

[0024] — said radial wall comprises an annular shoulder and a radial flange annular extending downstream of this shoulder;

[0025] — the stop disc extends around the X axis;

[0026] — the thrust disc comprises a radial extension, a first axial extension and a second axial extension which extend on either side of the radial extension;

[0027] — the first axial extension is connected to the second longitudinal end of the tree;

[0028] — the thrust disc is hollow and comprises a bore;

[0029] — said second stop is an annular part extending around the X axis and having a general C shape;

[0030] — the annular part of the second stop comprises a vertical annular wall and a longitudinal annular wall extending axially downstream of this vertical wall;

[0031] — the vertical wall of the second stop comprises a central opening;

[0032] — the second axial extension of the stop disc is inserted into the central opening of the vertical wall of the second stop;

[0033] - the shaft comprises a tie rod extending along the X axis and inside a bore of the tree;

[0034] — the tie rod is a bar of elongated shape along the X axis;

[0035] — the tie rod bar extends between a third longitudinal end of shape annular and a fourth longitudinal end in the shape of a T;

[0036] - the fan comprises an annular, warp-shaped nozzle extending around of said downstream cone, said nozzle comprising at least a third orifice for the passage of air from said vein inside said body to said second orifices;

[0037] - the second air passage orifices are two to fifteen in number, and by example of three;

[0038] - each of said second orifices has a diameter of between 3 and 20 mm, and for example 6 mm.

[0039] The invention also relates to an aircraft comprising at least one electric fan according to the invention. Brief description of the figures

[0040] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0041] [Fig-1] [Fig.l] is a schematic perspective view of an electric fan for an aircraft;

[0042] [Fig.2] [Fig.2] is a schematic axial sectional view of the fan of [Fig.l] according to one embodiment of the invention;

[0043] [Fig.3] [Fig.3] is a schematic sectional view of an air guide bearing of the fan of [Fig.2];

[0044] [Fig.4] [Fig.4] is a schematic sectional view along line YY of [Fig.2];

[0045] [Fig.5] [Fig.5] is a schematic axial sectional view of the fan of [Fig.2] illustrating a circulation of an air flow inside the fan according to one embodiment of the invention. Detailed description of the invention

[0046] Generally speaking, in the description below, the terms “longitudinal” and “axial” describe the orientation of structural elements extending in the direction of a longitudinal axis X. This axis X can be confused with an axis of rotation of a rotor. The terms “radial” or “vertical” describe an orientation of structural elements extending in a direction perpendicular to the axis X. The terms “inner” and “outer”, and “internal” and “external” are used with reference to a positioning relative to the axis X. Thus, a structural element extending along the axis X has an inner face facing the axis X and an outer surface, opposite its inner surface.

[0047] Aircraft may include a ventilation system for a cockpit and / or for a cabin. Aircraft may also include an avionics bay having various electronic equipment that must be cooled by a ventilation system.

[0048] The ventilation system may be part of a larger aircraft environmental control system assembly. The environmental control system is configured to receive ambient air, condition that ambient air, and supply the air conditioned to various systems, such as the cockpit or cabin ventilation system.

[0049] With reference to [Fig. 1], in an aircraft A, conditioned air may be supplied to the cockpit, the avionics bay and / or the cabin by means of an electric fan 10. Figures 2 to 5 illustrate a non-limiting embodiment of the fan 10 of the invention.

[0050] The fan 10 comprises several components, such as a tubular casing 1, a body 2, a shaft 3, a fan wheel 4, an electric motor 5, a first guide air bearing 6, a second guide air bearing 7 and an axial annular thrust disc 86.

[0051] The casing 1 extends along and around a longitudinal axis X. In [Fig.l], the casing 1 is open on one of these longitudinal ends, in particular on the side of the ventilation wheel 4 in order to capture the air. This air captured by the wheel 4 can come from preconditioned air and channeled by an upstream pipe and / or a downstream pipe which can be integrated into the fan. For example, ambient air can be captured by the wheel 4, in this case a filter is integrated into this pipe.

[0052] The body 2 also extends along the axis X and inside the casing 1. The body 2 and the casing 1 define between them an annular flow vein V of a main air flow. For example, the vein V has a first diameter Dv of between 80 and 140 mm. Preferably, the first diameter Dv is approximately 110 mm. The first diameter Dv is measured radially (relative to the axis X) between the casing 1 and the body 2.

[0053] In the present application, the terms “upstream” and “downstream” are defined with respect to the direction of circulation of the air flow in the fan, in particular from the ventilation wheel 4 (corresponding to upstream) to an end of the fan opposite the wheel 4 (corresponding to downstream). More particularly, the air flow substantially upstream of the vein V (in particular at the outlet of the wheel 4) has a first pressure F1 and this same air flow downstream of the vein V (in particular at a distance from the wheel 4) has a second pressure F2. As described above, the first pressure F1 is higher than the second pressure F2, due to the pressure losses which are present in the vein V (for example due to the presence of holes in the fan, the friction of air against the walls of the fan and / or the presence of rectifiers).

[0054] The body 2 comprises an upstream cone 22, a central portion 24 and a downstream cone 26. In [Fig.2], the central portion 24 and the upstream cone 22 are formed from a single piece.

[0055] In particular, the upstream cone 22 comprises an outer annular portion 222, an inner annular portion 224 and a transverse annular wall 226 connecting the inner 224 and outer 222 annular portions together. The outer portion 222, the inner portion 224 and the transverse wall 226 may be in one piece (i.e. made from one material), such as as illustrated in [Fig.2].

[0056] The transverse wall 226 can extend, on the one hand, radially towards the outside of the internal part 224, and on the other hand, radially towards the inside of an upstream annular edge 22a of the external part 222. In the example of [Fig.2], an end opposite the upstream annular edge 22a is connected to the central portion 24.

[0057] The transverse wall 226 may be substantially inclined relative to the X axis. The angle of inclination of the transverse wall 226 may be between 30° and 90°. In the example of [Fig. 2], the transverse wall 226 is inclined by approximately 80° relative to the X axis.

[0058] The internal part 224 and the transverse wall 226 can therefore form a first annular support for the first bearing 6, so that the upstream cone 22 carries the first bearing 6. In particular, the internal part 224 extends around the first bearing 6.

[0059] In the example, the wheel 4 is arranged upstream of the upstream cone 22. An annular air passage space 220 ([Fig.5]) separates the upstream cone 22 from the wheel 4. By way of example, this space 220 is of the order of a few micrometers to a few millimeters.

[0060] The wheel 4 also extends around the axis X. The wheel 4 comprises a hub of revolution which comprises an external conical wall 42 (relative to the axis X), an internal annular wall 44 and blades 46. The internal wall 44 is connected, on the one hand, radially to the external wall 42, and on the other hand, axially to the shaft 3. In the example of the figures, the internal wall 44 comprises a first central bore 440 configured to receive at least a portion of a tie rod 300. The blades 46 each extend radially towards the outside of the external wall 42.

[0061] The central portion 24 may comprise a cylindrical wall which extends around the axis X. With reference to Figures 2 and 5, the central portion 24 extends substantially from the electric motor 5 to the second bearing 7. Rectifier blades 27 may extend radially outward from the cylindrical part of the central portion 24. These rectifier blades 27 are distributed regularly around the axis X. The rectifier blades 27 may be located axially between the first bearing 6 and the second bearing 7.

[0062] The cylindrical part of the central portion 24 may also comprise a free downstream annular edge 24a, which is in particular opposite the upstream edge 22a. The downstream edge 24a is axially spaced from the downstream cone 26 in the example of [Fig.2].

[0063] The central portion 24 may also comprise a flange 29 for fixing the body 2 to the casing 1. In particular, the flange 29 extends radially from the cylindrical part of the central portion 24, in particular from the downstream edge 24a. By way of example, the flange 29 and a fragment of the casing 1 are connected to each other by fixings (such as screws).

[0064] In the example of the figures, the body 2 comprises an annular chamber 20. This chamber 20 is delimited by the external part 222, the cylindrical part of the central portion 24, the upstream cones 22 and downstream cones 26.

[0065] The downstream cone 26 comprises at least one first orifice 260 configured for the passage of air from the vein V inside the body 2.

[0066] The shaft 3 extends along the axis X and inside the body 2. The shaft 3 is a rotary or rotating shaft. In the example of the figures, the shaft 3 comprises a first longitudinal end 32, an opposite second longitudinal end 34 and a first middle portion 36 connecting the first and second ends 32, 34 together. The first middle portion 36 and the first and second ends 32, 34 are in one piece in the example. The first end 32 is supported by the first bearing 6 and the second end 34 is supported by the second bearing 7. Thus, the first bearing 6 and the second bearing 7 make it possible to support and guide the rotating shaft 3 in rotation. For example, the shaft 3 has a second diameter D3 of between 15 and 25 mm, the second diameter being measured radially to the X axis. Preferably, D3 is approximately 22 mm.

[0067] The shaft 3 may also comprise a second bore 30. In the example of the figures, the tie rod 300 is mounted in the second bore 30. In a variant not illustrated, the fan 10 comprises the shaft 3 without a tie rod with or without a second bore 30.

[0068] The shaft 3 may be integral with the wheel 4. In particular, the first end 32 is connected to the internal wall 44 of the wheel 4. For this, the internal wall 44 is inserted into the second bore 30.

[0069] The shaft 3 may also be integral with an axial annular thrust disc 86 downstream of the fan. More particularly, the second end 34 is connected to a first axial annular extension 862 of the thrust disc 86. For this, the first extension 862 is inserted into the second bore 30.

[0070] The tie rod 300 may be an elongated bar. The tie rod 300 extends along the axis X and inside the shaft 3. In particular, the tie rod 300 is mounted inside the second bore 30 of the shaft, the first bore 440 of the inner wall 44, a third bore 868 of the stop disc 86 and a fourth bore 920 of a support 92 of the fan 10. In the example of the figures, the tie rod 300 comprises a third longitudinal end 302, a fourth longitudinal end 304 opposite the third end 302 and a second middle portion 306 connecting these third 302 and fourth 304 ends.

[0071] In the example of the figures, upstream of the fan 10, the impeller 4 and the first end 32 of the shaft extend around the third end 302 of the tie rod. For this, the third end 302 is mounted in the first bore 440. This third end 302 may have a generally cylindrical shape. The third end 302 may have an excess thickness compared to the thickness of the second middle portion 306. Downstream of the fan, the stop disc 86 and the support 92 extend around the fourth end 304 of the tie rod. For this, the fourth end 304 is mounted in the third 868 and fourth 920 bores. In the example, the fourth end 304 has a general T shape which is mounted inside the support 92. The tie rod 300 generally has a support function for assembling / disassembling the various components of the fan and for centering the various components of the fan.

[0072] The electric motor 5 is mounted inside the body 1 and around the shaft 3, in particular around the first middle portion 36 of the shaft. The electric motor 5 may comprise a rotor 52 and a stator 54. The rotor 52 is generally cylindrical in shape and rotatably mounted around the axis X. The stator 54 extends around the rotor 52. The electric motor 5 may also comprise an active part 56 (or winding) which comprises armatures formed from ferromagnetic materials and windings wound around these armatures. In the example, the active part 56 comprises a second opening 560 extending around the axis X. This active part 56 extends through and on either side of the stator 54.

[0073] In the example, the first bearing 6 is located upstream of the electric motor 5, while the second bearing 7 is located downstream of the electric motor 5.

[0074] The first 6 and second 7 guide bearings are of the air (or foil) type. These bearings 6, 7 may be a radial bearing and / or a thrust bearing allowing the rotation of the shaft 3 relative to the body 2 on a film of fluid (such as air). Thus, in the example of FIGS. 2 and 5, the first bearing 6 is a radial bearing, and the second bearing 7 is a radial bearing and an axial thrust bearing, in particular formed by a first axial annular stop 82.

[0075] With reference to [Fig. 3], each of the bearings 6, 7 may comprise an annular sleeve 62, 72, flexible sheets 64, 74 and corrugated sheets 66, 76. The corrugated sheets 66, 76 are interposed between the sleeve 62, 72 and the flexible sheets 64, 74. The flexible sheets 64, 74 are positioned around the shaft 3 of the fan. Air passages 60, 70 are also provided between the shaft 3 and the flexible sheets 64, 74. These passages 60, 70 (such as openings) make it possible in particular to cool the bearings and limit heating of the bearings due to shearing of the air between the sheets of the bearing and the shaft.

[0076] In operation, the shaft 3 is rotating, in particular between a first speed and a second speed. As described in the technical background, the first speed (for example approximately 3,000 rpm) corresponds to the maximum speed of contact of the sheets 64, 74 with the shaft 3. The second speed (for example approximately 10,000 rpm) corresponds to the minimum speed of detachment of the sheets 64, 74 of the tree.

[0077] As mentioned above, the first bearing 6 is carried by the upstream cone 22, in particular by the internal part 224 and the transverse wall 226. The second bearing 7 is carried by the first axial annular stop 82.

[0078] Advantageously, the fan 10 also comprises the first axial annular stop 82 and a second axial annular stop 84. These axial stops 82, 84 make it possible in particular to maintain the axial displacement of the shaft 3.

[0079] The first axial stop 82 may be a radial annular wall. This radial annular wall may have a general C-shape. The first axial stop 82 may comprise an annular shoulder 822 and an annular radial flange 824. In [Fig. 2], the radial flange 824 is interposed between the central portion 24 (in particular the downstream edge 24a and the downstream flange 29) and a second axial stop 84. The second axial stop 84, the downstream flange 29 and radial flange 824 are connected to each other by fasteners 80 (such as screws). In the example of the figures, the first axial stop 82 may be formed in a single piece (i.e. integrally) with the second bearing 7 to form a radial guide and axial stop bearing (Figures 2 and 5).

[0080] The thrust disc 84 may comprise a radial annular extension 864 and first 862 and second 866 axial annular extensions. The first 862 and second 866 axial annular extensions extend on either side of the radial extension 864. The radial extension 864 is inserted between the first axial stop 82 and the second axial stop 84. In the example, the first extension 862 has an external diameter smaller than that of the second extension 866. As mentioned above, the first extension 862 is inserted into the second bore 30, and the second extension 866 is inserted into a first central opening 848 of the second stop 84. For example, the stop disc 86 may have a third external diameter D86 of between 45 and 65 mm. Preferably, the third diameter D86 is approximately 55 mm.

[0081] The fan 10 may further comprise the second stop 84 mounted between the downstream cone 26 and the stop disc 86. In the example of the figures, this second stop 84 is an axial annular counter stop. The second stop 84 may be an annular part having a general C shape. This part of the second stop 86 may comprise a vertical annular wall 842 and a longitudinal annular wall 844 extending axially downstream of the vertical wall 842. The vertical wall 842 comprises the first opening 848. In Figures 2 and 5, this first opening 848 is delimited between the stop disc 86 and the second stop 84 (in particular between the second extension 864 and the vertical wall 842). The vertical wall 842 extends substantially parallel to the radial extension 866 of the thrust disc 86 and to the first axial stop 82. The longitudinal wall 844 comprises a second radial flange 846. This second radial flange 846 and the first radial flange 824 may be connected to the downstream flange 29 by fasteners 80 (such as screws). The longitudinal wall 844 may be connected to the downstream cone 26 by fasteners 90 (such as screws).

[0082] Advantageously, the first 82 and second 84 axial stops are air (or foil) thrust bearings. These axial stops 82, 84 may be similar to the bearings 6, 7 of [Fig. 3]. The first axial stop 82 and / or the second axial stop 84 may comprise at least one smooth sheet and at least one corrugated sheet. In particular, the smooth sheet is in contact with the shaft 3, while the corrugated sheet is not in contact with the shaft 3 to enable the stiffness and damping functions of the first axial stop 82. In the example of [Fig. 2], the smooth and corrugated sheets are arranged on an upstream face of the vertical wall 842 of the second axial stop 84.

[0083] The fan 10 may comprise the support 92 allowing the positioning and centering of the tie rod 300 relative to the downstream cone 26. For this, the support 92 comprises the fourth bore 920 for receiving at least one downstream portion of the tie rod 300. This fourth bore 920 may thus have a shape complementary to the fourth longitudinal end 304 of the tie rod 300. The support 92 is secured to the stop disk 86. Preferably, the support 92 is inserted inside the second extension 864. The support 92 is in particular mounted inside the downstream cone 26. In the example, the first orifice 260 extends between the downstream cone 26 and the support 92.

[0084] The fan 10 may also comprise an annular end piece 9. The end piece 9 has a warp shape. The end piece 9 extends around the downstream cone 26. The end piece 9 comprises at least one third orifice 900. This third orifice 900 is configured for the passage of air from the vein V towards the interior of the body 2 and in particular to the upstream cone 22. In [Fig. 2], the end piece 9 is connected to the second stop 84 (in particular on the longitudinal part 844) and to the downstream cone 26 by the fasteners 90.

[0085] The fan 10 may also comprise an annular magnet 94. This magnet 94 is mounted inside the downstream cone 26 and around the axis X. In Figures 2 and 5, the magnet 94 extends around the support 92. The magnet 94 makes it possible to position the rotor 52 of the electric motor on the shaft 3. The position of the magnet 94 makes it possible to know the angular position of the rotor of the electric motor relative to the stator. This position of the rotor can be measured by Hall effect sensors at the level of the magnets 94 (not shown in the figures) and supported by a part 96.

[0086] One of the particularities of the invention lies in the fact that the upstream cone 22 (in particular the transverse wall 226) comprises second orifices 280 and that the body 2 comprises several air passages P1, P2, P3, P4.

[0087] With reference to figures 2, 4 and 5, the transverse wall 226 comprises the second orifices 280. These second orifices 280 can be regularly distributed around the axis X. By way of example, the second orifices 280 are two to fifteen in number. Preferably and as illustrated in [Fig. 4], the second orifices are three in number. Also by way of example, each of the second orifices 280 has a fourth diameter D280 of between 3 and 20 mm. Preferably, the diameter D280 of each of the second orifices is approximately 6 mm.

[0088] The different air passages PI, P2, P3, P4 according to the invention are defined by openings and / or spaces (or interstices) between the components of the body 2 of the fan 10. More particularly, the body 2 comprises: - a first air passage PI connecting the first orifice 260 to the second bearing 7, - a second air passage P2 connecting the first air passage PI to the electric motor 5, - a third air passage P3 connecting the second air passage P2 to the first bearing 6, and - a fourth air passage P4 connecting the third air passage P3 to the second orifices 280.

[0089] In the example of [Fig.5], the first 82 and second 84 axial stops and the stop disc 86 are spaced apart from each other by spaces suitable for the passage of air.

[0090] For example, these elements 82, 86, 84 are separated by a few micrometers to a few millimeters. Thus, a first gap 860 is defined between the stop disc 86 and the second stop 84. A second gap 820 is delimited by the first stop 82 and the stop disc 86. The first 860 and second 820 gaps extend in a direction radial to the axis X. An annular cavity 840 may also be present around the first 82 and second 84 axial stops and the stop disc 86. This cavity 840 is in fluid communication, on the one hand, with the first orifice 260, and on the other hand, with the chamber 20 and the first and second gaps 860, 820. The cavity 840 and the first 860 and second 820 gaps can therefore form the first passage PL

[0091] A third gap 540 may also be provided between the rotor 52 and the stator 54. This third gap 540 extends in an axial direction to the axis X. The second opening 560 of the active part 56 is in fluid communication, on the one hand, with the third gap 540, and on the other hand, with the chamber 20 and a third opening 70 of the second bearing 7. Thus, the third 70 and second 560 openings and the third gap 540 can therefore form the second passage P2.

[0092] The third passage P3 can be formed by the air flow exiting the second opening 560. This air flow enters a fourth opening 60 of the first bearing 6 and / or exits this fourth opening 60 in the direction of the chamber 20 of the body 2 and / or in the direction of the wheel 4.

[0093] The fourth passage P4 may be formed by the air flow exiting from the second opening 560 or from the fourth opening 60, and passing through the second orifices 280 to open into the annular vein V downstream of wheel 4.

[0094] These passages PI, P2, P3, P4 make it possible to create a cooling circuit (or ventilation or air circulation), in particular in a single direction from downstream to upstream, inside and in the chamber 20 of the body 2. This circuit makes it possible to preferentially cool the first and second guide bearings 6, 7 and the first and second axial stops 82, 84, in order to limit the pressure losses due to the shearing of the air between the sheets of the bearings 6, 7 and the stops 82, 84.

[0095] We will now describe the cooling circuit inside the body 2 of the fan 10 which is generated by the orifices 260, 280 and the air passages P1, P2, P3, P4, with reference to [Fig.5].

[0096] In operation, the fan 10 is supplied by an initial air flow F0 coming from the environment outside the fan and entering the fan 10 through the ventilation wheel 4. This initial air flow F0 is compressed by the blades 46 of the wheel 4 to generate the first air flow pressure F1 at the outlet of the wheel 4 which opens into the duct V of the fan. The air flow then passes through the blades of the rectifier 27 to reach in particular a second pressure F2 of the same air flow. This second pressure F2 downstream of the duct V therefore has a pressure lower than the first pressure F1 upstream of the duct V. The air flow with the second pressure F2 passes inside the body 2 through the first orifice 260, and also through the third orifice 900 when the nozzle 9 is mounted on the body 2.Inside the body 2, this air flow passes through the first passage P1 to cool the first and second axial stops 82, 84, then this air flow passes through the second passage P2 in order to ventilate and cool the second bearing 7. At the outlet of the second passage P2, the air flow divides to pass into the third passage P3 to ventilate and cool the first bearing 6 and / or pass into the fourth passage P4 passing through the second orifices 280 to open into the vein V of the fan 10. This cooling circuit thus makes it possible to provide the cooling necessary for the proper operation of the air bearings 6, 7 (and in particular the air stops 82, 84) by a single inlet (via the first orifice 260) of a single source of air flow in the body 2.

[0097] In this description, the electric fan is described in an aircraft. The fan of the invention can also be adapted to ventilation systems other than in the aeronautical field.

[0098] Furthermore, it is understood from the present description that the ventilation efficiency of the guide bearings (such as the reference parts 6 and 7) and / or the axial stops (such as the reference parts 82 and 84) within the fan is dependent on various parameters, such as the dimensions (shape, size, materials, etc.) of the fan body and the rotating shaft relative to the other components of the fan.

[0099] Overall, this proposed solution is simple, efficient and economical to produce and assemble on an electric fan, in particular of an aircraft, while ensuring optimal operation and an improved service life of the air bearings (and consequently also that of the fan).

Claims

Claims

1. Electric fan (10) for an aircraft (A), comprising: - a tubular casing (1) extending along and around a longitudinal axis (X), - a body (2) extending along the axis (X) and inside said casing (1), the body (2) and the casing (1) defining between them an annular flow path (V) for an air flow, the body (2) comprising an upstream cone (22), a central portion (24) and a downstream cone (26), the downstream cone (26) comprising at least a first air passage orifice (260) from said flow path (V) inside said body (2), - a shaft (3) extending along the axis (X) and inside the body (2), - a ventilation wheel (4) carried by a first longitudinal end (32) of the shaft (3), - an electric motor (5) mounted inside the body (1) and around the shaft (3), - a first air bearing (6) for guiding the shaft (3) located upstream of the electric motor (5) and carried by the upstream cone (22),- a first axial annular stop (82) connected to the central portion (24), - a second air bearing (7) for guiding the shaft (3) located downstream of the electric motor (5) and carried by the first axial annular stop (82), - a second axial annular stop (84) connected to the downstream cone (26), and - an axial annular stop disc (86) carried by a second longitudinal end (34) of the shaft opposite said first end (32), characterized in that several air passages (PI, P2, P3, P4) are provided inside said body (2) to convey said air flow (F1, F2) from said first orifice (260) to the upstream cone (22) of the first air bearing (6), this upstream cone (22) comprising second orifices (280) for the passage of this air, and in that said second orifices (280) of air passages are formed in a transverse wall (226) of the upstream cone (22) which is connected to the central portion (24) of the body (2).,

2. Fan (10) according to claim 1, characterized in that it comprises: - a first air passage (PI) connecting said first orifice (260) to the second air bearing (7), - a second air passage (P2) connecting the first air passage (PI) to the electric motor (5), - a third air passage (P3) connecting the second air passage (P2) to the first air bearing (6), and - a fourth air passage (P4) connecting the third air passage (P3) to the second orifices (280).

3. Fan (10) according to claim 1 or 2, characterized in that the axial annular stop disc (86) is interposed between the first (82) and second (84) axial annular stops.

4. Fan (10) according to any one of the preceding claims, characterized in that said second air bearing (7) and said first axial annular stop (82) are formed in one piece.

5. A fan (10) according to any preceding claim, characterized in that the shaft (3) comprises a tie rod (300) extending along the axis (X) and inside a bore (30) of the shaft (3).

6. Fan (10) according to any one of the preceding claims, characterized in that it comprises an annular end piece (9) in the shape of an ogive extending around said downstream cone (26), said end piece (9) comprising at least one third orifice (900) for the passage of air from said vein (V) inside said body (2) to said second orifices (280).

7. Fan (10) according to any one of the preceding claims, characterized in that the second air passage orifices (280) are two to fifteen in number, and for example three.

8. Fan (10) according to any one of the preceding claims, characterized in that each of said second orifices (280) has a diameter (D28o) of between 3 and 20 mm, and for example 6 mm.

9. Aircraft (A) comprising at least one fan (10) according to any one of the preceding claims.

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