Assembly of two casings for an aircraft propulsion unit

Abstract

The invention relates to an assembly (102) of two annular casings (200, 202) for an aircraft propulsion unit, these casings having a single axis (A) of revolution and comprising a first fan casing (200) extending around fan blades, and a second casing (202) which extends from the first casing and which has an outer annular wall (204), the wall extending around the axis and comprising, at one longitudinal end, a first annular flange (204a) for fastening to an annular flange (200b) of the first casing, the second casing also having annular reinforcing ribs (204c, 204d) which extend radially outward from an outer face (S1) of the wall, the second casing further having at least one axial reinforcement (204e) projecting from the outer face, and extending parallel to the axis between two reinforcing ribs and / or between one of the reinforcing ribs and the first flange.

Description

Description TITLE: SET OF TWO CRANKS FOR AN AIRCRAFT PROPELLER ASSEMBLY Technical field of the invention

[0001] The present invention relates to a set of housings for a propulsion assembly, for example of an aircraft, a propulsion assembly comprising this assembly and a method for manufacturing such an assembly. Technological background

[0002] Documents FR-A1-3 146160, W0-A1-2013 / 095210, FR-A1-3121 168, EP-A2-1 927728 and FR-A1-3129 175 are known from the prior art.

[0003] A propulsion unit 100, as illustrated for example in figure 1, includes a turbomachine 104, integrated into a housing assembly 102.

[0004] The turbomachine 104 includes, from upstream to downstream in the direction of gas flow (airflow direction F), a blower 208 and a gas generator which may include one or more compressor stages, including a low-pressure compressor stage 216. The gas generator may further include a high-pressure compression stage (not shown), a combustion chamber, one or more turbine stages, high pressure then low pressure, and an exhaust nozzle.

[0005] Each compressor of the turbomachine 104 includes at least one movable rotor rotating around a longitudinal axis X of the turbomachine 104.

[0006] The set of 102 housings can include a first housing 200, called the blower housing, and a second housing 202, called the intermediate housing, flanged to each other.

[0007] For the purposes of this application, the following definitions apply: "Longitudinally" or "longitudinal" means any direction parallel to the X-axis, and "radially" or "radial" means any direction perpendicular to the X-axis. Similarly, by convention in this application, the terms "internal" and "external" are defined radially with respect to the X-axis. Finally, the terms "upstream" and "downstream" are defined with respect to the direction of gas flow in the propulsion assembly 100.

[0008] An airflow F driven by the fan 208 is separated by a nozzle of an inter-vein structure 220 into a primary airflow F1 entering the gas generator of the turbomachine 104 and a secondary airflow F2 contributing predominantly to the thrust provided by the turbomachine 104. The secondary airflow F2 flows around the gas generator in a secondary duct 214. The primary airflow flows in a primary duct 212.

[0009] With further reference to Figure 1, the second casing 202 is located longitudinally between the low pressure compressor 216 and the high pressure compressor (not shown).

[0010] More specifically, the second casing 202 includes an inner hub 206 and an annular wall or outer ferrule 204 extending around the hub 206 and forming with the latter a portion of the secondary vein 214. The inner hub 206 further includes an annular opening 206b defining a portion of the primary vein 212. The portion of the secondary vein 214 is separated radially from the portion of the primary vein 212 by an inter-vein compartment 220a integrated into the inter-vein structure 220, the compartment 220a being for example intended for the passage of servicing lines.

[0011] The outer annular wall 202 is connected to the inner hub 206 by guide vanes 222 (approximately radial with respect to the longitudinal axis X of the turbomachine 104), more commonly known by the English acronym OGV for "Outlet Guide Vane," and distributed evenly around the X-axis. Some of these OGV vanes 222 are configured to withstand external forces and form the framework of the second casing 202, and are therefore called structural vanes. These structural vanes are more commonly referred to as "arms."

[0012] With further reference to Figure 1, the second housing 202 includes an upstream flange 204a fixed to a downstream flange 200b of the first housing or blower housing 200 via a plurality of bolts 224 distributed regularly around the X axis.

[0013] Each OGV blade comprises an aerodynamically profiled blade 222a, elongated in shape, delimited longitudinally by a leading edge positioned upstream along the direction of gas flow in the second casing 202, and by a trailing edge opposite the leading edge. The blade 222a is further delimited radially between an inner platform 220c and an outer platform 222b. The inner and outer platforms 220c and 222b are respectively attached to the inner hub 206 and the outer wall 204 of the second casing 202 by means of removable fasteners 224 (here, screws and / or bolts).

[0014] The portion of the inter-vein structure 220 located longitudinally upstream of the second casing 202 supports, in particular, a stator 216a of the low-pressure compressor 216. The fan 208 comprises a plurality of blades 208a, each having a blade with an aerodynamic profile delimited radially by an external end free to face the first casing 200 and a foot fixed to a fan disk 208b. The rotor 216b of the low-pressure compressor 216 is fixed to the fan disk 208b. The fan disk 208b is rotationally connected to a shaft 218a of a bearing 218, the base 218b of which is fixed to an annular flange 206a projecting from the internal hub 206.

[0015] Damage to the aircraft fuselage (e.g., an airplane), in the event of blade loss or debris entering the fan 208, can greatly affect the safety of the crew and passengers (if, for example, debris strikes a fuel-filled wing or the pressurized fuselage, or if the turbomachinery detaches). Therefore, the first casing 200, or fan casing, is designed to retain the fan blades 208a in the event of their breakage or debris entering the fan 208.

[0016] The first 200 housing also ensures mechanical continuity (of forces and moments) between an air intake sleeve (not shown) and the second 202 housing or intermediate housing.

[0017] The breakage of a blade 208a of the blower 208 can therefore generate axial (for example compression) and radial deformations propagating at the level of the outer wall 204 of the intermediate casing 202 due to the transmission of forces from the first casing 200.

[0018] With reference to Figure 2, the wall 204 of the second casing may include reinforcing annular ribs 204c, 204d which extend around an axis A of revolution of the casing assembly 102 passing through the axis X of the propulsion assembly 100. The reinforcing ribs 204c, 204d extend radially outwards from an external annular face S1 of the wall 204.

[0019] These reinforcing ribs 204c, 204d allow the wall 204 to resist radial deformations that can be transmitted to the second casing 202 by the first casing 200, for example, in the event of a blower blade 208a breaking

[0020] However, when wall 204 is subjected to axial deformations T, as illustrated in Figure 2, cracks 240 may appear on the outer wall 204 of the second casing 202, weakening it. Indeed, the outer wall 204 may have lower mechanical strength in the axial direction and therefore may not withstand certain axial stresses. This weakening of the outer wall 204 of the second casing 202 can thus affect the integrity of the propulsion assembly 100.

[0021] It may therefore be desirable to provide a set of housings that allows us to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0022] It is therefore proposed that there be a set of two annular casings for an aircraft propulsion assembly, these casings having the same axis of revolution and comprising a first fan casing configured to surround fan blades, and a second casing extending in line with the first casing, the second casing having an external annular wall extending around the axis of revolution and comprising at one longitudinal end a first radially external annular flange for attachment to an annular flange of the first casing, the second casing further comprising reinforcing annular ribs which extend around the axis of revolution and which extend radially outwards from an external annular face of the wall, these reinforcing ribs being formed in one piece with said wall and being at axial distances from each other and from said first flange,characterized in that the second casing further comprises at least one axial reinforcement of said wall, said at least one axial reinforcement being projecting from said external face of the wall and extending parallel to said axis of revolution, between two reinforcing ribs and / or between one of the reinforcing ribs and said first flange.

[0023] Thus, thanks to the invention it is possible to improve the mechanical strength of the outer wall of the second crankcase and therefore to guarantee the structural integrity of the parts of the crankcase assembly and the propulsion assembly.

[0024] In the event of extreme transient events, such as the failure of a fan blade, the reinforcements can deform or crack instead of the outer wall of the second casing. This deformation or damage to the reinforcements dissipates energy, thus ensuring the integrity of the casing assembly and consequently the propulsion system.

[0025] The invention also allows for a reduction in mass while strengthening the mechanical integrity of the outer wall or shell of the second casing. Indeed, proper dimensioning of the axial reinforcements or fusible links reduces the amount of material or parts used to reinforce the wall and consequently reduces the wall thickness.

[0026] The invention may further include one or more of the following optional features, in any technically feasible combination: the second casing includes several axial reinforcements distributed around the axis of revolution; the axial reinforcements are formed in one piece with the wall and the reinforcing ribs; the axial reinforcements each have a general elongated and straight shape; the axial reinforcements each have a radial thickness or dimension, measured with respect to said axis, which is less than a radial thickness or dimension of at least some of the reinforcing ribs and / or a radial thickness or dimension of the first flange; the axial reinforcements are added and fixed to said external annular face of the external annular wall of the second casing; Each of the axial reinforcements has a general U-shape and includes a middle portion extending between two lateral tabs, the middle portion being located on said external face of the wall and the lateral tabs being applied and fixed, respectively, to one of the reinforcing ribs, and to the first flange or to another of the reinforcing ribs; the axial reinforcements are distributed in annular rows around said axis, at least some of the axial reinforcements of one of the rows being axially aligned with at least some of the axial reinforcements of another of the rows; the number of axial reinforcements in each row is the same; the axial reinforcements belonging to three rows of axial reinforcements are aligned axially with each other; the number of axial reinforcements in each row is different; the axial reinforcements include areas of weakness so as to be fusible when stressed, particularly axially; the areas of weakness are formed by notches or recesses; the areas of weakness are located in the middle of the axial reinforcements relative to their extent along said axis.

[0027] The invention also relates to a propulsion assembly comprising at least: a set of two housings as described above; and a turbomachine integrated into said assembly.

[0028] The invention also relates to a method for manufacturing a set of two annular housings for an aircraft turbomachine as described above, the method comprising at least one step of making the annular wall of the second housing, the making step comprising at least one substep of forming at least one axial reinforcement on the annular wall, the at least one reinforcement being projecting on said external annular face of the wall and extending parallel to said axis of revolution, between two reinforcing ribs and / or between one of the reinforcing ribs and said first flange.

[0029] The process may also include one or more of the following optional features, in any technically feasible combination: the axial reinforcements are formed in one piece with the wall and the reinforcing ribs; the axial reinforcements are added and fixed to the outer annular face of the outer annular wall of the second casing. Brief description of the figures

[0030] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: Figure 1 is a longitudinal half-sectional view of a propulsion assembly comprising a set of casings and a turbomachine; Figure 2 is a partial longitudinal half-sectional view of the casing assembly according to the prior art; Figure 3 is a partial longitudinal half-section view of the housing assembly according to a first embodiment of the invention; Figure 4 is a partial longitudinal half-section view of the housing assembly according to a second embodiment of the invention; Figure 5 is a partial longitudinal half-section view of a variant of the housing assembly in Figure 3; Figure 6 is a partial longitudinal half-section view of a variant of the housing assembly in Figure 4; Figure 7 is a radial cross-sectional view of the external wall of a second housing according to the invention; Figure 8 is a partial perspective view of the external wall of a second housing according to the invention; and Figure 9 is a schematic view of a method for manufacturing a set of housings according to the invention. Detailed description of the invention

[0031] By convention, in the description below, the term "axial" refers to the orientation of structural elements extending along an axis. This axis corresponds approximately to an axis of rotation or revolution. The term "radial" refers to the orientation of structural elements extending in a direction perpendicular to the axis of rotation or revolution. The terms "interior" and "exterior," "front" and "rear," "internal" and "external" are used with reference to positioning relative to the axis of rotation or revolution. Thus, a structural element extending along the axis of rotation or revolution has an interior face or surface facing the longitudinal axis and an exterior face or surface opposite its interior face or surface.Similarly, a portion of a structural element that extends radially towards the axis of rotation or revolution will be considered a front portion, and a portion of the same structural element that extends radially away from the axis of rotation or revolution will be considered a rear portion.

[0032] Figures 1 and 2 have already been described above. Figure 1 shows an example of a propulsion assembly 100, particularly for an aircraft, in which the invention can be implemented. The propulsion assembly 100 comprises at least one turbomachine 104 integrated into a housing assembly 102.

[0033] In the example shown in Figure 1, the turbomachine is a dual-flow type. However, those skilled in the art will understand that this example is not limiting, and that the invention can be implemented in any propulsion system comprising a turbomachine integrated into a set of housings.

[0034] With reference to figure 3, a first embodiment of an assembly 102 of housings according to the invention will now be described.

[0035] As already mentioned above, in relation to Figures 1 and 2, the assembly 102 of housings comprises at least a first fan housing 200 and a second housing 202. The first 200 and second 202 housings have the same axis A of revolution passing through the longitudinal axis X of the turbomachine 104. The first 200 and second 202 housings can be made of metallic or composite material.

[0036] The first housing 200, configured to surround the blower blades 208a, includes at least one upstream flange 200a (as illustrated in Figure 2) and one downstream flange 200b.

[0037] The second housing 202, which extends from the first housing 200, comprises an external annular wall 204 extending around the axis of revolution A. The external annular wall 204 has, at one longitudinal end, a first annular flange 200a, or upstream flange, radially external. The first flange 204a is fixed to the downstream annular flange 200b of the first housing 200 by means of a screw or bolt 224. The external wall 204 includes an internal face S2 to which one end of the guide vanes 222 is fixed.

[0038] The second housing 202 further comprises annular reinforcing ribs 204c, 204d, or stiffeners, which extend around the axis A of revolution. The ribs 204c, 204d also extend radially outwards from an external annular face S1 of the wall 204, opposite the internal face S2. The reinforcing ribs 204c, 204d are formed as a single piece with said wall 204 and are axially spaced from each other and from the first flange 204a.

[0039] Referring again to Figure 3, the second housing 202 also includes at least one axial reinforcement 204e of the wall 204. The axial reinforcement 204e projects from the external face S1 of the wall 204 of the second housing 202 and extends parallel to the axis A of revolution of the second housing 202, between one of the reinforcing ribs 204c, 204d and the first flange 204a. In the example in Figure 3, the axial reinforcement 204e extends between the first flange 204a and the third rib 204d.

[0040] In a second embodiment illustrated in figure 4, the second housing includes axial reinforcements 204e arranged between two reinforcing ribs 204c, 204d and between a reinforcing rib 204c and the first flange 204a.

[0041] The axial reinforcements 204e are attached and fixed, by means of screws 224, to said external annular face S1 of the external annular wall 204 of the second housing 202.

[0042] Each of the axial reinforcements 204e has a general U-shape and comprises a central part 300 and two lateral tabs 302. The central part 300 extends between the two tabs 302 and is located on the external face S1 of the wall 204 of the second housing 202. The lateral tabs 302 are applied and fixed, by means of screws 224, respectively to one of the reinforcing ribs 204c, 204d, and to the first flange 204a or to another of the reinforcing ribs 204c, 204d.

[0043] With reference to Figure 5, a variant of the first embodiment (Figure 3) of the set 102 of housings 200, 202 will now be described.

[0044] In this variant, at least one axial reinforcement 204e of the second housing 202 includes at least one weak zone ZF so as to be fusible when subjected to stress, particularly axial stress. The weak zone ZF is formed by at least one notch or recess 204f.

[0045] The presence of the ZF zone of weakness thus allows the wall 204 of the second casing to support static and vibratory loads but also to deform sufficiently to dissipate energy in the event of extreme transient events such as the rupture of a blower blade 208a.

[0046] With reference to Figure 6, a variant of the second embodiment (Figure 4) of the assembly 102 of housings 200, 202 will now be described.

[0047] Each of the axial reinforcements 204e includes at least one ZF zone of weakness so as to be fusible when subjected to stress, particularly axial stress. Each ZF zone of weakness is formed by at least one notch or recess 204f.

[0048] In this configuration, where the reinforcements are added and fixed to the wall 204 of the second casing 202, each reinforcement 204e acts as a fuse. Since each reinforcement is not an integral part of the wall 204, there is no risk of crack propagation.

[0049] The creation of a well-dimensioned ZF zone of weakness makes it possible to obtain fuses 204e capable of dissipating a large amount of energy via damage to the material. This energy dissipation then makes it possible to guarantee a structural integrity of the wall 204 of the second casing 202.

[0050] With reference to figure 7, the annular wall 204 has a thickness dR defined as a difference between an outer diameter D2 delimited by the outer face S1 of the outer wall 204, and an inner diameter D1 delimited by the inner face S2 of the outer wall 204.

[0051] The axial reinforcements 204e each have a radial thickness or dimension L2, measured with respect to the axis A. This dimension represents an extra thickness above the external diameter D2 of the external wall 204. This thickness can also be measured from the external face S1 of the wall 204.

[0052] Each axial reinforcement 204e may also have a dimension (not shown), measured along an axis tangent to the outer wall, which is less than a dimension between two flanges or between a flange and a reinforcing rib between which the axial reinforcement is located.

[0053] The ribs 204c, 204d and / or the first flange 204a of the outer wall 204 of the second housing 202 also have a radial thickness or dimension L1 measured with respect to axis A. This dimension represents an excess thickness above the outer diameter D2 of the outer wall 204 and can also be measured from the outer face S1 of the wall 204. The radial thickness or dimension L2 of the axial reinforcements 204e is less than the radial thickness or dimension L1 of at least some of the reinforcing ribs 204c, 204d and / or the first flange 204a.

[0054] With reference to figure 8, the second casing 202 may include several axial reinforcements 204e distributed around the axis A of revolution.

[0055] The 204e axial reinforcements can be distributed in annular rows around axis A. For example, the 204e axial reinforcements can be distributed every 30° around axis A.

[0056] In the example in Figure 8, the wall 204 comprises three adjacent annular rows ra1, ra2, ra3. A first row ra1 is formed by the first flange 204a of the wall 204 of the second housing 202 and a first reinforcing rib 204c of the wall; a second row ra2 is formed by the first reinforcing rib 204c of the wall and a second reinforcing rib 204c of the wall 204; and a third row ra3 is formed by the second reinforcing rib 204c of the wall 204 and a third reinforcing rib 204d of the wall 204. The first row includes at least one axial reinforcement 204e that is axially aligned with axial reinforcements 204e of the second ra2 and third ra3 rows, respectively.

[0057] The number of axial reinforcements 204e per row may be different as illustrated in figure 8 or, in another variant (not shown), be the same.

[0058] In another variant (not shown), the number of axial reinforcements 204e per row ra1, ra2, ra3 is the same, and the axial reinforcements 204e belonging to these rows ra1, ra2, ra3 are aligned axially with each other. Preferably, the outer wall 204 of the second housing 202 has three rows. Those skilled in the art will understand that this number is not exhaustive.

[0059] The invention also relates to a method 400 for manufacturing an assembly 102 of two annular housings 200, 202, as described above, for an aircraft turbomachine 104.

[0060] The process 400 for manufacturing the assembly 102 of two annular housings 200, 202 includes at least one step of making 402 of the annular wall 204 of the second housing 202., The making step 402 includes at least one substep of forming 600 of at least one axial reinforcement 204e on the annular wall 204.

[0061] The axial reinforcement (204e) is projecting on the external annular face S1 of the wall 204 and extends parallel to the axis A of revolution, between two reinforcing ribs 204c, 204d and / or between one of the reinforcing ribs 204c and said first flange 204a.

[0062] The axial reinforcements 204e can be formed 600 in one piece with the wall 204 and the reinforcing ribs 204c, 204d or, added and fixed on the outer annular face S1 of the outer annular wall 204 of the second housing 202.

[0063] In the case where the axial reinforcements 204e are formed as a single piece with the wall 204, the axial reinforcements 204e and the wall 204 are made of the same material (e.g., aluminum). Since the wall 204 is generally rolled, the manufacturing process may also include machining between the axial reinforcements 204e and the ribs 204c, 204d.

[0064] In cases where axial reinforcements 204e are added and fixed to the outer wall 204, these added axial reinforcements 204e can be solid or hollow. The material can be, for example, metallic (aluminum or other) or composite. In this case, the manufacturing process can be machining or additive manufacturing, etc.

[0065] Advantageously, those skilled in the art will understand that the axial reinforcement or fuse 204e, by virtue of its deformation, cracking, or damage, dissipates energy in the event of extreme transient events (for example, the rupture of a blade 208a of the blower 208) in order to guarantee the structural integrity of the outer wall 204 of the second casing 202. Thus, the invention makes it possible to improve the structural integrity of the assembly 102 of casings including the second casing 202, but also of a propulsion assembly 100 including this assembly 102 of casings.

[0066] The invention also allows a gain in mass while strengthening the mechanical strength of the outer wall or ferrule of the second casing 202. Indeed, a good dimensioning of the axial reinforcements or fuses 204e makes it possible to reduce the quantity of material or part(s) used for the reinforcement of the wall and consequently to reduce the thickness of the wall.

[0067] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Demands [1] Assembly (102) of two annular housings (200, 202) for an aircraft propulsion assembly (100), these housings (200, 202) having the same axis (A) of revolution and comprising a first fan housing (200) configured to surround fan blades (208a), and a second housing (202) extending in line with the first housing (200), the second housing (202) having an external annular wall (204) extending around the axis (A) of revolution and comprising at one longitudinal end a first radially external annular flange (204a) for attachment to an annular flange (200b) of the first housing (200), the second housing (202) further comprising reinforcing annular ribs (204c, 204d) extending around the axis (A) of revolution and extending radially outwards from an external annular face (S1) of the wall (204), these reinforcing ribs (204c,204d) being formed in one piece with said wall (204) and being axially spaced from each other and from said first flange (204a), characterized in that the second housing (202) further comprises at least one axial reinforcement (204e) of said wall (204), said at least one axial reinforcement (204e) being projecting from said external face (S1) of the wall (204) and extending parallel to said axis of revolution, between two reinforcing ribs (204c, 204d) and / or between one of the reinforcing ribs (204c) and said first flange (204a), the axial reinforcements (204e) being formed in one piece with the wall (204) and the reinforcing ribs (204c, 204d). [2] Assembly (102) of two annular housings according to claim 1, wherein the second housing (202) comprises several axial reinforcements (204e) distributed around the axis (A) of revolution. [3] Assembly (102) of two annular housings according to claim 1 or 2, wherein the axial reinforcements (204e) each have a generally elongated and straight shape. [4] Assembly (102) of two annular housings according to claim 3, wherein the axial reinforcements (204e) each have a radial thickness or dimension (L2), measured with respect to said axis (A), which is less than a radial thickness or dimension (L1) of at least some of the reinforcing ribs (204c, 204d) and / or a radial thickness or dimension (L1) of the first flange (204a). [5] Assembly (102) of two annular housings according to any one of claims 1 to 4, wherein the axial reinforcements (204e) are attached and fixed to said outer annular face (S1) of the outer annular wall (204) of the second housing (202). [6] Assembly (102) of two annular housings according to claim 5, wherein each of the axial reinforcements (204e) has a general U-shape and comprises a middle portion (300) extending between two lateral tabs (302), the middle portion (300) being located on said external face (S1) of the wall and the lateral tabs (302) being applied and fixed, respectively, to one of the reinforcing ribs (204c, 204d), and to the first flange (204a) or to another of the reinforcing ribs (204c, 204d). [7] Assembly (102) of two annular housings according to claim 5 or 6, wherein the axial reinforcements (204e) are distributed in annular rows around said axis (A), at least some of the axial reinforcements (204e) of one of the rows being aligned axially with at least some of the axial reinforcements (204e) of another of the rows. [8] Assembly (102) of two annular housings according to claim 7, wherein the number of axial reinforcements (204e) of each of the rows is the same. [9] Assembly of two annular housings according to claim 8, wherein the axial reinforcements (204e) belonging to three rows of axial reinforcements (204e) are aligned axially with each other. [10] Assembly (102) of two annular housings according to claim 7, wherein the number of axial reinforcements (204e) of each of the rows is different. [11] Aircraft propulsion assembly (100) comprising at least: an assembly (102) according to one of the preceding claims; and a turbomachine (104) integrated into said assembly (102); [12] Method (400) of manufacturing an assembly (102) of two annular housings for an aircraft turbomachine (104) according to any one of claims 1 to 10, the method comprising at least one step (402) of making the annular wall (204) of the second housing (202), the making step (402) comprising at least one substep (600) of forming at least one axial reinforcement (204e) on the annular wall (204), the at least one reinforcement (204e) being projecting on said external annular face (S1) of the wall (204) and extending parallel to said axis (A) of revolution, between two reinforcing ribs (204c, 204d) and / or between one of the reinforcing ribs (204c) and said first flange (204a). [13] Method (400) of manufacturing an assembly (102) of two annular housings according to claim 12, in which the axial reinforcements (204e) are formed in one piece with the wall (204) and the reinforcing ribs (204c, 204d). [14] Method (400) of manufacturing an assembly (102) of two annular housings according to claim 12, wherein the axial reinforcements (204e) are attached and fixed to the external annular face (S1) of the external annular wall (204) of the second housing (202).

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