HOUSING WITH INTERNAL REINFORCEMENTS

Description

GENERAL TECHNICAL FIELD

[0001] The invention relates to a turbomachine casing and in particular a turbomachine exhaust casing. STATE OF THE ART

[0002] The exhaust casing is a structural part of a turbomachine located at the outlet of a turbine, the outlet comprising a gas ejection nozzle.

[0003] The housing typically comprises a hub, an outer shell, and radial arms arranged circumferentially between the hub and the outer shell. Document EP 2 003 293 A1 discloses an example of such a housing.

[0004] In order to fix the exhaust casing to a turbomachine support (a pylon for example), yokes are provided projecting from the external shell.

[0005] The exhaust casing is therefore subjected to tensile and compressive forces which can damage the casing as well as the casing arms. It is particularly at the junction between the hub and the arms that the stresses are greatest and the forces are significant.

[0006] To enable the casing to withstand these stresses, it is usual to provide extra thicknesses in the high stress areas, which leads to an increase in the mass of the structure. PRESENTATION OF THE INVENTION

[0007] The invention proposes to improve the resistance to stresses of a turbomachine casing.

[0008] To this end, the invention proposes, according to a first aspect, a turbomachine casing, extending around an axis, said casing comprising: a hub comprising an outer wall and an inner wall between which an annular flange extends; an outer ferrule; a plurality of arms which each extend between the hub and the outer ferrule; the casing further comprising a plurality of main stiffeners, each being arranged in the extension of an arm between the external wall and the internal wall projecting from the flange, each stiffener comprising two ribs arranged opposite each other and which move away from each other as they move away from the external wall towards the internal wall.

[0009] The invention, according to the first aspect, is advantageously supplemented by the following characteristics, taken alone or in any of their technically possible combinations.

[0010] Each rib includes a rod arranged in the extension of an arm.

[0011] The two ribs of each main stiffener extend relative to each other, diverging circumferentially on either side of an arm.

[0012] The casing further comprises secondary stiffeners, each comprising two plates fitted opposite each other on the ribs of each main stiffener, leaving a gap between them, said gap constituting a clearance suitable for being used up in the event of deformation of one or more ribs.

[0013] The housing further includes internal stiffeners arranged to extend opposite each other in each of the arms and each extending between two opposing walls of the arm.

[0014] The internal stiffeners are arranged in the part of the arm which has the greatest thickness in the transverse direction of said arm.

[0015] Each internal stiffener comprises a rod extended by a head, the heads of said rods being arranged opposite each other leaving a gap between them, said gap constituting a clearance suitable for being consumed in the event of deformation of the arm.

[0016] The heads arranged opposite each other have complementary shapes and preferably have a circular or rectangular section forming a complementary male and female part.

[0017] Each arm has a main extension direction each internal stiffener of each arm extends mainly in the arm according to the main extension direction of the arm.

[0018] The invention proposes, according to a second aspect, a turbomachine comprising a casing according to the first aspect of the invention.

[0019] The invention proposes, according to a third aspect, an aircraft comprising a turbomachine according to the second aspect of the invention.

[0020] The arrangement of main stiffeners possibly coupled with secondary and / or internal stiffeners leads to a stiffening of the casing when it is subjected to high stresses, which allows it to better support them.

[0021] In addition, the addition of stiffeners avoids the need for extra thickness in the areas concerned and therefore limits the increase in the mass of the structure.

[0022] The resulting casing is therefore both stronger and lighter than a known casing which would have extra thicknesses for resistance to stresses. PRESENTATION OF FIGURES

[0023] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which: there figure 1 illustrates an overall view of an exhaust casing according to an embodiment of the invention figure 2 illustrates a detail of a portion of the exhaust casing according to an embodiment of the invention; the figures 3 et 4 illustrate a detail of a rib of an exhaust casing according to an embodiment of the invention; the figure 5 illustrates an arm comprising internal ribs according to one embodiment of the invention; the figures 6 à 8 illustrate an arm comprising internal ribs according to one embodiment of the invention.

[0024] In all figures, similar elements have identical references. DETAILED DESCRIPTION

[0025] There figure 1 illustrates a turbomachine casing 1 comprising a hub 2 which extends around a longitudinal axis XX'.

[0026] In the following, the terms "internal", "external", "radial", "axial" are located in relation to this axis, it being understood that an internal element is closer to the axis than an external element.

[0027] Coming back to the figure 1 , the hub 2 comprises an external wall 21 and an internal annular wall 22 between which an annular flange 23 extends.

[0028] Radial arms 4 are arranged circumferentially between the hub 2 and an external shell 3 of the casing 1. The arms 4 are regularly distributed around the hub 2.

[0029] Forks 6 for connection to a pylon (not shown) of the turbomachine are arranged on the external shell 3. On the figure 1 , three connecting screeds 6 are present.

[0030] In relation to the figures 2 And 3, to reinforce the casing at the arms, the latter comprises radial main stiffeners 5 which extend each arm. These main stiffeners 5 are in particular arranged inside the hub 2 and project from the annular flange 23. As can be seen in the figure 2 , each main stiffener 5 has a general shape that is substantially V-shaped.

[0031] In particular, the main stiffeners 5 extend by diverging circumferentially on either side of each arm 4. In this respect and advantageously, each main stiffener comprises two ribs 51, 52 facing each other which extend by diverging from a downstream rod 53 which is directly arranged in the extension of an arm 4. The two ribs 51, 52 are constituted by walls which diverge by extending from the rod 53 towards the flange 23 as far as the internal wall 22.

[0032] As is particularly visible on the figure 2 3 , one side 51a, 52a of each rib is in contact with the flange 23 while another side 51b, 52b of each rib is in contact with the internal wall 22.

[0033] These main stiffeners 5 are arranged regularly inside the hub 2 as can be seen in the figure 1 .

[0034] This arrangement of the main stiffeners 5 makes it possible to reinforce the mechanical strength of the casing at the level of the arms 4.

[0035] In a complementary manner, in relation to the figure 4 , secondary stiffeners 7 are attached to the main stiffeners 5: one secondary stiffener 7 per main stiffener 5. In particular, these secondary stiffeners 7 are formed by two plates 71, 72 facing each other attached to the ribs 51, 52 of the main stiffeners 5, leaving a gap between them, said gap (denoted "e" in the figure) constituting a clearance suitable for being consumed in the event of deformation of the main stiffeners 5. Indeed, when the main stiffeners 5 are going to deform, the two plates 71, 72 of the secondary stiffeners 7 will move closer together thanks to the clearance and come into contact. This contact has the effect of absorbing the forces, of generally stiffening the hub and of preventing excessive deformation at this level.

[0036] In addition to the main and / or secondary stiffeners positioned in the hub, the housing may include internal stiffeners arranged in the structure of the arm.

[0037] According to one embodiment, illustrated in the figure 5 , an internal stiffener 8 is arranged perpendicular to the Y axis of the arm (defining a main direction of the arm). Such an internal stiffener 8 comprises two internal ribs 81, 82 facing each other inside the arm and arranged with a gap e' so as to constitute a clearance suitable for being consumed in the event of deformation of the arm. In particular, the ribs 81, 82 extend from two opposite walls 41, 42 of the arm 4. The internal ribs 81, 82 fill the arm leaving the clearance e' in the middle. The internal ribs 81, 82 are therefore facing each other. The shape of each internal rib 81, 82 can be likened to an internal platform filling the section with a slot in its middle.

[0038] According to an embodiment illustrated in the figure 6 , an internal stiffener 9, is arranged in the axis of the arm. Such a stiffener 9 comprises two internal ribs 91, 92 facing each other over a portion of the length of the arm arranged with a gap between them so as to constitute a clearance suitable for being consumed in the event of deformation of the arm. In particular, these ribs 91, 92 are arranged on walls 41, 42 of the arm 4 facing each other.

[0039] As illustrated on the figures 7 et 8 these internal ribs can take the form of rods 93, 94 provided with complementary heads 93a, 93b, 94a, 94b of circular or square section and of complementary shape (a male part and a female part).

[0040] On the figure 7 , the male part (O-shaped) has a solid spherical or cylindrical section while the female part (C-shaped) has a spherical or cylindrical section including an opening to accommodate the male part.

[0041] On the figure 8 , the male part (T-shaped) has a solid rectangular section while the female part (C-shaped) has a rectangular section including an opening to accommodate the male part.

[0042] As can be seen on the figure 7 et 8 These two parts are arranged relative to each other leaving a gap in several directions in order to constitute a corresponding clearance which can be consumed in the event of deformations of the arms.

[0043] These ribs allow, after deformation of the arm, to consume the existing play between the male part and the female part and thus come into contact between parts 93a and 93b or between parts 94a and 94b. This contact has the effect of absorbing the forces, of generally stiffening the arm and of preventing excessive deformation at this level.

[0044] Furthermore, as is visible on the figures 5 , 7 et 8, the internal stiffeners are advantageously arranged in the part of the arm which has the greatest transverse thickness (the transverse direction being a direction perpendicular to the Y direction of the arm). It is in fact in this zone that strong stresses are likely to be applied to the arm.

[0045] In addition, the internal or external ribs are obtained by an additive manufacturing process which allows complex shapes to be provided in areas that are difficult to access.

[0046] Alternatively, the internal ribs can be made during the manufacture of the arms which could be in two parts assembled together by welding.

Claims

1. A turbomachine casing (1) extending about an axis (X), said casing (1) comprising: - a hub (2) comprising an outer wall (21) and an inner wall (22), between which an annular flange (23) extends; - an outer shell (3); - a plurality of arms (4) each extending between the hub (2) and the outer shell (3); the casing (1) further comprising a plurality of main stiffeners (5), each arranged in the extension of an arm (4) between the outer wall (21) and the inner wall (22) protruding from the flange (23), each main stiffener (5) comprising two ribs (51, 52) arranged opposite each other and diverging from each other away from the outer wall (21) towards the inner wall (22).

2. The casing as claimed in claim 1, in which each rib (51, 52) comprises a rod (53) arranged in the extension of an arm (4).

3. The casing according to one of the preceding claims, in which the two ribs (51, 52) of each main stiffener (5) extend circumferentially away from one another on either side of an arm (4).

4. The casing according to one of the preceding claims, further comprising secondary stiffeners (7) each comprising two plates (71, 72) fitted opposite one another on the ribs (51, 52) of each main stiffener (5), leaving a gap between them, said gap constituting a clearance adapted to be consumed in the event of deformation of one or more ribs (51, 52).

5. The casing according to one of the preceding claims, further comprising internal stiffeners (8, 9) arranged facing each other in each of the arms (4) and each extending between two opposite walls (41, 42) of the arm (4).

6. The casing as claimed in claim 5, in which the internal stiffeners (8, 9) are arranged in that part of the arm (4) which is thickest in the transverse direction of said arm (4).

7. The casing according to one of claims 5 to 6, in which each internal stiffener (9) comprises a rod (91, 92) extended by a head (93a, 93b, 94a, 94b), the heads of said rods being arranged opposite each other leaving a gap between them, said gap constituting a clearance adapted to be consumed in the event of deformation of the arm (4).

8. The casing according to the preceding claim, in which the heads (93a, 93b, 94a, 94b) arranged opposite each other have complementary shapes and preferably have a circular or rectangular cross-section forming a complementary male and female part.

9. A The casing according to one of claims 5 to 8, wherein each arm (4) has a main extension direction (Y), each internal stiffener (9) of each arm (4) extending mainly into the arm (4) along the main extension direction (Y) of the arm (4).

10. Turbomachine comprising a casing (1) according to one of the preceding claims.