CRANKCASE INCLUDING A TURBOMACHINE EXHAUST DRAIN

Abstract

CRANKCASE COMPRISING A TURBOMACHINE EXHAUST DRAIN One aspect of the invention relates to a crankcase comprising a drain (D) for the evacuation of liquids through a discharge orifice (60) in a wall (6), the drain comprising a base (1) including a receiving channel (110), and a frustoconical external mounting surface (111). The drain includes a first nut (2) cooperating with the threaded external surface (112) of the base (1) to compress the frustoconical external mounting surface (111) against a corresponding frustoconical portion (601) of the wall (6) defining the discharge orifice (60). The drain further includes a drainage tube (3) comprising a discharge conduit (30) and a fitting head (31) connected to one end of the discharge conduit (30). The drain also includes a second nut (4) for connecting the connecting head (31) of the drainage tube (3) to the base (1) by compressing them to connect the channel (110) to the evacuation conduit (30).Figure to be published with the abbreviation: Figure 1A.

Description

Title of the invention: CRANKCASE INCLUDING A TURBOMACHINE EXHAUST DRAIN TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of the evacuation of liquids out of the exhaust casings of turbomachine via drains and a turbomachine comprising such an exhaust casing equipped with drains.

[0002] The present invention relates to a turbomachine housing comprising a drain and a turbomachine comprising such a housing. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] As described in document FR2913725, it is common for liquids such as water, fuel, or oil to be retained in the exhaust housing of a turbomachine. The stagnation of these liquids is undesirable, particularly given the risks of fire and freezing. To remedy this problem, prior art housings generally include an orifice equipped with a drain to evacuate the liquids retained in the exhaust housing. This drain is generally formed of a cylindrical body comprising a section fully welded to the housing at the level of the discharge orifice and a drainage tube extending from the body. However, the welding process requires the addition of material, which can obstruct the discharge orifice. In such cases, an operator must manually remove the excess material from the drain orifice to unblock it.Furthermore, when the engine hood is open, the vein drain tube is exposed to numerous risks of damage due to various environmental factors, leading to a complete replacement of the drain.

[0004] Such an operation is lengthy and delicate for the operator. Document FR2913725 therefore proposed a new type of drain to remedy this problem, featuring a skirt crimped into the exhaust housing opening. This type of drain simplifies its installation in the exhaust housing, as unclogging the drain opening is no longer necessary. However, as described in document FR303761, crimping this drain is less effective than welding. Document FR303761 also proposes a drain comprising a first part welded to one face of a housing wall, passing through it, and a second part screwed to the first part and then welded to the second surface of the wall opposite the first.Such a drain simplifies the installation of the drain; however, for disassembly it is necessary to break the weld points and then unscrew the second part from the first part in order to remove the . drain. Without these welds, the first part needs to be held in place during disassembly, complicating the disassembly since it is necessary to have a tool inside the cylinder head to hold it.

[0005] Other fluid recovery solutions exist, as described in documents FR3098242 and FR3098243. These require a plate comprising a collecting portion attached to an opening in the cylinder head and fastening means on either side of the plate. This necessitates the use of means for attaching a flange to the cylinder wall to secure a fluid recovery unit. Therefore, if this plate is changed or installed, the flange must be removed and reinstalled. Furthermore, this solution can cause a sealing problem between the cylinder head surface and the plate.

[0006] Document FR3106613 describes yet another solution comprising two drains connected together by a connecting piece on one side of the crankcase wall, screwed to both drains on either side and secured by an anti-rotation wire. Such an assembly is complex to install, particularly due to the insertion of the connecting piece inside the cylinder head.

[0007] There is therefore a need to replace a drain tube easily without having a complex assembly or disassembly of the drain to the cylinder head and without the need to use means of fixing a flange. Summary of the invention

[0008] The invention offers a solution to the problems mentioned above, by allowing to have means of fixing only on the outside without adding means of fixing to the cylinder head while being able to dismantle the drainage tube.

[0009] One aspect of the invention relates to a turbomachine housing comprising: • An annular wall comprising: • a radially internal surface, • a radially external surface opposite the radially internal surface, • a drainage orifice passing from the radially internal surface to the external surface, the drainage orifice comprising a frustoconical portion extending from the radially internal surface to the radially external surface, • a drain comprising a base including: • an inlet end and an outlet end opposite the inlet end, • a channel opening at the inlet end and at the outlet end, • an external frustoconical mounting surface mounted on the frustoconical part from the drain opening, • an external threaded surface between the frustoconical external mounting surface and the output end, • an internal connecting surface delimiting a part of the channel up to the outlet end. The drain of the part according to the first aspect of the invention further comprises: • a first connecting nut which extends around and cooperates with the threaded external surface of the base to compress the frustoconical external mounting surface against the frustoconical part of the discharge orifice, • a drainage pipe comprising a discharge conduit and a connecting head attached to one end of the discharge conduit, the connecting head comprising an external connecting surface which cooperates with the internal connecting surface of the base, • a second nut to connect the fitting head of the drainage tube to the base by compressing the internal connection surface of the base against the external connection surface so as to fluidly connect the channel of the base to the discharge conduit of the drainage tube.

[0010] Thanks to the invention, it is possible to change the drain tube or the discharge pipe without using any tools inside the cylinder head. During a drain tube or pipe change operation, the operator can maintain the tightness between the base and the cylinder head wall from the outside using this first nut, while simultaneously allowing the tube to be removed from the base via its fitting. Furthermore, the frustoconical external mounting surface, secured to the wall by the first nut, simplifies assembly while ensuring a good seal between the wall and the base.

[0011] By "truncated conical portion of the discharge orifice" is meant the truncated conical surface of the annular wall delimiting (around) a portion of the volume of the discharge orifice. In other words, the annular wall comprises a surface of revolution defining the orifice, the surface of revolution comprising at least one truncated conical portion having a diameter that increases as it approaches the first end.

[0012] In addition to the characteristics mentioned in the preceding paragraph, the casing according to one aspect of the invention may have one or more complementary characteristics among those described in the following paragraphs, considered individually or according to all technically possible combinations.

[0013] According to one embodiment, the base includes an axial stop and the drain pipe connection head includes a threaded external surface, the second nut comprising a stop surface bearing against the axial stop and being screwed onto a threaded external surface of the connection head. This allows the drainage pipe to be changed. without risk of losing the second nut.

[0014] According to an example of this embodiment, the base includes a stop groove located between the external threaded surface and an external surface of a portion comprising the internal connecting surface of the base, the base further comprising a removable ring mounted in the stop groove, forming the axial stop.

[0015] According to one variant, the connecting head of the drainage tube includes an axial stop and the base includes an external threaded surface, the second nut connecting the drainage tube to the base by coming against the axial stop and being screwed onto the external threaded surface.

[0016] According to one embodiment, the internal connecting surface of the base is frustoconical, and wherein the channel of the base includes an outlet opening comprising the largest diameter of the internal frustoconical surface, and wherein the external connecting surface of the connecting head is a curved frustoconical surface which cooperates with the internal connecting surface to form a seal.

[0017] According to one embodiment, the base includes a shoulder forming an external cylindrical surface extending from the internal connecting surface of the base and the first nut includes an internal cylindrical surface cooperating with the external cylindrical surface.

[0018] According to one embodiment, the casing is a turbine exhaust casing and the annular wall is a downstream annular wall, and in which the casing includes an upstream annular wall which is intended to surround a ring of rotating blades, the upstream annular wall being frustoconical along the axis and including at its upstream end an upstream flange fixed to a downstream flange arranged at the downstream end of the downstream annular wall.

[0019] A second aspect of the invention relates to a turbomachine comprising a casing according to the first aspect of the invention and a ring of rotating turbine blades mounted to rotate around the axis, the ring of rotating blades being surrounded by the upstream annular wall.

[0020] A third aspect of the invention relates to a method for mounting a drain on an annular wall of a turbomachine housing according to the first aspect of the invention comprising: • a step of inserting a body of the base into the drain opening from the inside to the outside of the wall, • a step of inserting the first nut, around the body of the base, after the step of inserting the body of the base, • a watertight assembly step including: • a sub-step of screwing the first nut onto the external surface threaded until the first nut is against the wall, then • a tightening sub-step compressing the external frustoconical mounting surface against a corresponding frustoconical portion of the wall, • a connection step by screwing the second nut onto a surface threaded fitting head or base to compress the internal connection surface to the external connection surface so as to connect the base channel to the drainage tube outlet.

[0021] According to an embodiment of this mounting method, in which the drain base has a body including a groove, the method includes a step of inserting the second nut around a body of the base and then a step of inserting the ring into the groove to form the axial stop with the stop surface of the second nut closer to the wall than the groove.

[0022] According to an example of this embodiment of this mounting method, the second nut includes an internal groove and a deformation orifice opening onto the head and the internal groove, the method including a step of positioning the second nut on the body of the base so that the groove to form the axial stop is opposite the internal groove.

[0023] A fourth aspect of the invention relates to a method for changing a drain tube of a fluid recovery assembly of a turbomachine according to the first aspect of the invention, comprising:

[0024] • a step of unscrewing the second nut, a step of changing the drainage tube with a new drainage tube and a step of connecting by screwing the second nut onto a threaded surface of the fitting head or the base body to compress the internal connection surface to the external connection surface of the new drainage tube connecting the channel to the drain conduit.

[0025] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0026] The figures are presented for illustrative purposes only and are in no way limiting of the invention.

[0027] [Fig.1A] shows a schematic representation of a cross-section of a drain according to an example of an embodiment of the invention for the evacuation of liquids through an evacuation orifice of a wall of a turbomachine casing.

[0028] [Fig. IB] shows part of a wall of the cylinder head of the [Fig. 1 A].

[0029] [Fig.2] shows a three-dimensional schematic representation of a body of a drain base of [Fig.1A].

[0030] [Fig.3] shows a three-dimensional schematic representation of a first nut of the drain of [Fig.1A].

[0031] [Fig.4] shows a three-dimensional schematic representation of a drainage tube from the drain of [Fig.1A].

[0032] [Fig.5a] shows a three-dimensional schematic representation of a second base nut of the drain of [Fig.1A].

[0033] [Fig.5b] shows a section of the second nut base of the drain of [Fig.5a].

[0034] [Fig. 5c] shows a section of part of the drain including the second nut of the [Fig.5a], part of the base 1 including a ring. DETAILED DESCRIPTION

[0035] The figures are presented for illustrative purposes only and are in no way limiting of the invention.

[0036] [Fig. 1A] shows a schematic representation of a cross-section of a portion of a turbomachine at the level of a casing 1 comprising an annular wall 6 and a drain D, according to an example of an embodiment of the invention for the discharge of liquids through a discharge port 60 of the annular wall 6 via the drain D. In this example, the drain D allows the recovery of low-pressure turbine fluid from the turbomachine. [Fig. 1B] shows a cross-section of a portion of the annular wall 6 at the level of the discharge port 60.

[0037] The annular wall 6 extends around an axis and includes a first orifice 60, passing between a volume, hereafter referred to as the inner volume, in the housing 1 protecting the blades 9 and an outer volume. The annular wall 6 may include other orifices spaced angularly with respect to each other (spaced circumferentially around the axis X). The annular wall 6 therefore has a radially internal surface 6i (also called the inner surface 6i) on the side of the inner volume and a radially external surface 6e (also called the outer surface 6e) opposite the radially internal surface, as well as a surface of revolution 600 (referenced in [Fig. 1B]) delimiting the discharge orifice 60 formed in the thickness of the wall joining the inner surface to the outer surface.In particular, the discharge orifice 60 includes a frustoconical part 601, i.e. the surface of revolution includes a frustoconical part extending from the internal surface 6i and a cylindrical part extending from the frustoconical part to the external surface 6e.

[0038] The annular wall 6 is frustoconical and extends along the axis of revolution, and comprises at its upstream end a flange portion 61 connected to a flange portion 71 of an outer ring 7 of the turbomachine housing 1, here in this case the exhaust housing of a low-pressure turbine, one blade 9 of which can be seen in the inner volume of a last annular row. The turbine blades 9 are surrounded by the outer ring 7 of the housing 1. The flange portion 61 and the flange portion 71 each comprise an orifice opposite each other and are connected by a bolt whose screw passes through this orifice. In addition, it can be seen that the wall includes a retention spout 62 whose end is further from the axis of revolution than a part of the discharge orifice 60 so that the liquid flows into the drain D through this discharge orifice 60.

[0039] The drain D includes a base 1 comprising a body 11 inserted from downstream (the inside of the annular wall 60) into the orifice 60. The base 1 is represented in a three-dimensional view in [Fig.2].

[0040] The body 11 comprises an inlet end on the inner side of the annular wall 60 and an outlet end opposite the inlet end on the outer side of the annular wall. The body 11 comprises a frustoconical external mounting surface 111 having a diameter that increases as it approaches the first end. This frustoconical external mounting surface 111 is in contact with the frustoconical portion of the surface of revolution of the wall 6, which defines the discharge orifice 60.

[0041] The body 11 comprises a channel 110 having an inlet opening 110i opening at the inlet end and an outlet opening 110o opening at the outlet end. The body 11 comprises a radially internal connecting surface 113 delimiting a portion of the channel up to the outlet 110o.

[0042] The body 11 further includes an external threaded surface 112 between the frustoconical external mounting surface 111 and the second end.

[0043] The drain D further comprises a first nut 2 shown in [Fig. 3] in a three-dimensional view and shown in [Fig. 1A] in cross-section, being tightly screwed onto the external threaded surface 112 of the body 11 of the base 1. The first nut 2 thus exerts a force against the external surface 6e and, through the thread, displaces the base 1 by compressing the frustoconical external mounting surface 111 against the frustoconical portion of the surface of revolution 601 of the wall 6, which defines the discharge orifice 60. The first nut 2 therefore comprises an orifice 20 through which the body 11 of the base 1 passes and an internal threaded surface 22 cooperating with the external threaded surface 112 of the body 11 of the base 1. The first nut 2 further comprises a head 21 comprising an external gripping surface 319 by a tool such as pliers or a wrench and the internal threaded surface 22.In this example, the nut 22 includes a stop and guide ring 26 comprising an external surface 26e, an internal cylindrical surface 26i delimiting a part of the orifice 20 and a radial surface 26r abutting against the external surface 6e of the wall 6. The body 11 of the base 1 includes a shoulder forming an external cylindrical surface 116 extending from the frustoconical mounting external surface 111 to a radial surface 116r of the shoulder from which extends the external threaded surface 112 having a diameter smaller than that of the external cylindrical surface 116. The external cylindrical surface 116 includes a part surrounded by the discharge orifice 60 and a part. surrounded by the cylindrical inner surface 26i. The cylindrical inner surface 26i has a longer axial length than the portion of the cylindrical outer surface 116 surrounded by the cylindrical inner surface 26i. Thus, the cylindrical outer surface 116 and the cylindrical inner surface 26i allow the discharge orifice 60 to be aligned with the channel 110 by means of the radial surface 26r bearing the first nut 2 against the wall 6. This improves the seal between the frustoconical outer mounting surface 111 and the frustoconical portion 601 of the wall 6.

[0044] The drain D further comprises a drainage tube 3 shown in three-dimensional view in [Fig. 4]. The drainage tube 3 comprises a discharge conduit 30 and a connecting head 31 connected to one end of the discharge conduit 30. The connecting head 31 comprises an external connecting surface 313 corresponding to the shape of the internal connecting surface 113 for cooperation. The drainage tube 3 shown in cross-section in [Fig. 1A] is connected to the shape of the internal connecting surface 113. In this example, the internal connecting surface 113 is in contact with the external connecting surface 313.

[0045] The drain D further includes a second nut 4 shown in three-dimensional view in [Fig. 5a] for connecting the connection head 31 of the drainage tube 3 to the base 1. [Fig. 5b] shows a cross-section along an axial plane of the second nut 4 and [Fig. 5c] also shows a cross-section along an axial plane of a portion of the base 1 comprising a downstream portion of the body 11 and a ring 14j surrounded by the second nut 4. As can be seen in [Fig. 1A], the second nut 4 allows the internal connection surface 113 to be compressed against the external connection surface 313, thus connecting the channel 110 to the channel of the drainage conduit 30.

[0046] Either the connecting head 31 or an element among the body 11 or the first nut 2 comprises a thread cooperating with the second nut 4 and respectively either one of the two elements or the connecting head 31 comprises an axial stop abutting against the second nut 4. In this embodiment, the connecting head 31 comprises an external threaded surface 314 cooperating with the second nut 4 and the base 1 further comprises an axial stop 14 abutting against the second nut 4. The second nut 4 is also represented by a section along an axial plane on [Fig. 5b]. The second nut 4 comprises a head 41 having an external gripping surface 419 for gripping by pliers or a wrench and an internal cylindrical surface 411 about an axis X delimiting a part of an orifice 40. The second nut 4 further comprises an internal threaded surface 46 delimiting the other part of the orifice 40. On the [Fig.lA], the internal threaded surface 46 is screwed with the external threaded surface 314. The internal cylindrical surface 411 includes an internal stop abutting against the rod 14j in the direction towards the drainage tube 3. The rod 14j. The base thus allows the body 11 and the second nut 4 to be joined together in translation by bearing against these two parts. [Fig. 5c] represents a section along an axial plane of an assembly comprising the second nut 4 and a part of the base 1 including the circlip 14j and the downstream part of the body 11. In this example, the internal stop is formed by an internal groove 414 referenced in [Fig. 5b], located opposite the external groove 115, visible in [Fig. 5c]. The internal groove 414 and the external groove 115 form a housing for the circlip 14j, thus limiting the axial displacement of the second nut 4 relative to the body 11 of the base 1 while allowing it to pivot along the axis of rotation X around this part of the body 11. The cylindrical surface has a smaller diameter than that of the external threaded surface 314 and as can be seen in the [Fig.lA], the internal groove and the external groove form a stop surface against the axial stop 14, thus allowing the internal connecting surface 113 to be compressed against the external connecting surface 313 during screwing.

[0047] In this example, the body 11 of the base 1 includes a stop groove 115, also called the external groove, located between the external threaded surface 112 and the internal connecting surface 113. The base 1 further includes a removable ring 14j mounted in the stop groove 115, one of whose surfaces delimiting the groove forms, together with the ring 14j, the axial stop 14. The ring 14j allows it to be mounted in the stop groove 115 after the body 11 of the base 1 has been inserted into the opening 40 of the second nut 4. The second nut 4 includes an internal groove 414 complementary to the stop groove 115, which together houses the ring 14j. In this example, the second nut 4 includes at least one deformation orifice 414j opening onto the head 41 and the internal groove 414. This allows the insertion of a rod into this deformation orifice 414j to form the circlip 14j by deformation and comes to rest in the housing formed by the internal groove 414j and the stop groove 115.The surfaces delimiting the internal groove 414j and the stop groove 115 are each axially abutted against the ring sandwiching the ring 14j. According to another example, the body 11 of the base 1 includes the axial stop 14 and the second nut 4 is bayoneted by inserting its shoulder into a notch in the axial stop 14 and then turning the second nut 4 so that the shoulder is abutted against the axial stop 14.

[0048] The connecting head 31 further includes an external gripping surface 319 for use with a tool such as pliers or a wrench.

[0049] In this example, the internal connecting surface 113 is frustoconical, such that the discharge outlet 113o comprises the largest diameter of the frustoconical internal surface 113. The external connecting surface 313 is a curved frustoconical surface in contact with the internal connecting surface 113 to form a seal. Thus, when tightened by a tool on each external gripping surface 419, 319 of the second nut 4 and of the connecting head 31, the internal shoulder of the nut against the axial stop 14 moves the connecting head 4 towards the base 1 by compressing the internal connecting surface 113 against the external connecting surface 313 in order to form a seal (a plastic or elastic deformation may be achieved during this deformation).

[0050] In this example, the body 11 of the base 1 includes a second groove 118 between the external threaded surface 112 and a collar 117 formed between this second groove 118 and the stop groove 115.

[0051] The external gripping surfaces 219, 319, 419 are all in this example surfaces having a hexagonal cross-section for key mounting.

[0052] In this example, the maximum diameter of the second nut 4, here measured at the external gripping surface 419, is greater than the smallest diameter of the discharge orifice 60 (here in the cylindrical part) as well as that of the smallest diameter of the first nut 2, here measured at the internal threaded surface 22. Thus, it is necessary to mount the second nut 4 after the mounting of the base body 1 and the first nut 2 as explained below.

[0053] The method for mounting drain D therefore comprises: • a step of inserting the body 11 of the base 1 into the discharge opening 60, from the inside to the outside of the wall 6, • a step of inserting the first nut 2, around the body 11 of the base 11, after the step of inserting the body 11, • a watertight assembly step comprising a sub-step of screwing the first nut 2 onto the external threaded surface 112 until the first nut 2 is pressed against the wall 6 and then a sub-step of tightening compressing the frustoconical external mounting surface 111 against a corresponding frustoconical part 601 of the wall 6 delimiting the discharge orifice 60, • a connection step by screwing the second nut 4 onto a threaded surface of the connecting head 31 or the base 11 (according to the other example not shown) to compress the internal connecting surface 113 to the external connecting surface 313 connecting the receiving channel 110 to the evacuation conduit channel 30 in a watertight manner.

[0054] The connection step can be achieved by screwing the second nut 4 onto a threaded surface of the connector head or the base body and until it abuts against an axial stop on the base or connector, respectively. In the example shown, the connection step is carried out by screwing the second nut 4 onto the external threaded surface 314 of the connector head 31 until the second nut is against the axial stop 14, thus compressing the radially internal connection surface 113 against the external connection surface 313.

[0055] Having a base 1 fixed by a first nut 2 to the outside of the wall 4 simplifies assembly. Furthermore, having a drainage pipe 3 connected by the second nut 4 to the base 1 simplifies the assembly operation.

[0056] The method further includes, before the screwing step, a step of inserting the second nut 4 around the body 11 of the base 11 and then a step of inserting a ring 14j into the groove 115 to form (by the surfaces forming the groove with the ring 14j) the axial stop 14 having the stop surface of the second nut 4 closer to the wall 4 than the groove 115.

[0057] Finally, in this example, having this second nut 4 mounted on the base 1 prevents the second nut 4 from being lost in case of a change of drain pipe 3.

[0058] The method may include in particular a step of inserting a rod into the deformation orifice 414j to form the ring 14j housed in the housing formed by the internal groove 414j and the stop groove 115. The method according to the example shown further includes a step of positioning the second nut 4 on the body 11 of the base 1 so that the groove 115 is opposite the internal groove 414.

[0059] The method for changing the drainage tube 3 therefore involves unscrewing the second nut 4 by applying a force with a tool on the external gripping surface 319 and an opposite force on the external gripping surface 419.

[0060] Next the method includes a step of changing drainage tube 3 by another drainage tube 3 and a connection step by screwing the second nut 4 in this case onto the threaded surface of the connecting head 31 until it is pressed against the axial stop 14 to compress the internal connecting surface 113 to the external connecting surface 313 of the new drainage tube 3 connecting the channel 110 to the evacuation conduit 30.

[0061] Unless otherwise specified, the same element appearing on different figures has a unique reference.

Claims

Claims

1. Turbomachine casing (1) comprising: an annular wall (6) which extends around an axis (X) and comprises: • a radially internal surface (6i), • a radially external surface (6th) opposite the radially inner surface (6i), • an evacuation orifice (60) passing from the radially internal surface (6i) to the radially external surface (6e), the evacuation orifice (60) comprising a frustoconical part (601) extending from the radially internal surface (6i) towards the radially external surface (6e), a drain (D) comprising: • a base (1) comprising:

1. an inlet end and an outlet end opposite the inlet end, 2. a channel (110) opening at the inlet end and at the outlet end, 3. a frustoconical external mounting surface (111) mounted on the frustoconical portion (601) of the discharge port (60), 4. a threaded external surface (112) between the frustoconical external mounting surface (111) and the outlet end, 5. an internal connecting surface (113) delimiting a part of the channel (110) up to the outlet end, • a first nut (2) which extends around and cooperates with the threaded external surface (112) of the base (1) to compress the frustoconical external mounting surface (111) against the frustoconical part (601) of the discharge orifice (60), • a drainage tube (3) comprising a discharge conduit (30) and a connection head (31) connected to one end of the discharge conduit (30), the connection head (31) comprising a surface external connecting surface (313) which cooperates with the internal connecting surface (113) of the base (1), • a second nut (4) for connecting the connecting head (31) of the drainage tube (3) to the base (1) by compressing the internal connecting surface (113) of the base (1) against the external connecting surface (313) so as to fluidically connect the channel (110) of the base (1) to the evacuation conduit (30) of the drainage tube (3).

2. Turbomachine casing (1) according to the preceding claim, in which the base (1) comprises an axial stop (14) and the connection head (31) of the drainage tube (3) comprises a threaded external surface (314), the second nut (4) comprising a stop surface (414) in abutment against the axial stop (14) and being screwed onto a threaded external surface (314) of the connection head (31).

3. Turbomachine casing (1) according to the preceding claim, in which the base (1) comprises a stop groove (115) located between the threaded external surface (112) and an external surface (119) of a portion comprising the internal connection surface (113) of the base (1), the base (1) further comprising a removable snap ring (14j) mounted in the stop groove (115) forming the axial stop (14).

4. Turbomachine casing (1) according to one of the preceding claims, in which the internal connection surface (113) of the base (1) is frustoconical, and in which the channel (110) of the base (1) comprises an outlet opening (1100) comprising the largest diameter of the frustoconical internal surface (113), and in which the external connection surface (313) of the connection head (31) is a curved frustoconical surface which cooperates with the internal connection surface (113) to form a seal.

5. Turbomachine casing (1) according to any one of the preceding claims, in which the base (1) comprises a shoulder forming a cylindrical external surface (116) extending from the internal connection surface (113) of the base (1) and the first nut (2) comprises a cylindrical internal surface (26i) cooperating with the cylindrical external surface (116).

6. Turbomachine casing (1) according to one of the preceding claims, in which the casing (1) is a turbine exhaust casing and the annular wall is a downstream annular wall (6), and in which the casing (1) comprises an upstream annular wall (7) which is intended to surround a ring of rotating blades (7), the upstream annular wall (6) being frustoconical along the axis (X) and comprising at its upstream end an upstream flange (61) fixed to a downstream flange (71) arranged at the downstream end of the downstream annular wall (7).

7. Turbomachine comprising a casing (1) according to the preceding claim and a ring of rotating turbine blades (9), mounted in rotation around the axis (X), the ring of rotating blades (9) being surrounded by the upstream annular wall (7).

8. Method for mounting a drain on an annular wall of a casing of a turbomachine according to one of claims 1 to 6, comprising: - a step of inserting a body (11) of the base (1) into the discharge orifice (60) from the inside to the outside of the wall (6), - a step of inserting the first nut (2), around the body (11) of the base (11), after the step of inserting the body (11) of the base (1), - a sealed mounting step comprising: • a sub-step of screwing the first nut (2) to the threaded external surface (112) until the first nut (2) rests against the wall (6) then, • a tightening sub-step compressing the frustoconical external mounting surface (111) against a corresponding frustoconical part (601) of the wall (6),- a connection step by screwing the second nut (4) onto a threaded surface of the connection head (31) or the base (11) to compress the internal connection surface (13) to the external connection surface (31) so as to connect the channel (110) of the base (1) to the discharge conduit (30) of the drainage tube (3).,

9. Mounting method according to the preceding claim, in which the base (1) of the drain (D) comprises a body (11) comprising a groove (115), the method comprising a step of inserting the second nut (4) around the body (11) of the base (11) and then a step of inserting a snap ring (14j) into the groove (115) to form the axial stop (14) by having the stop surface of the second nut (4) closer to the wall (4) than the groove (115).

10. Mounting method according to the preceding claim, in which the second nut (4) comprises an internal groove (414) and a deformation orifice (414j) opening onto the head (41) and onto the internal groove (414), the method comprising a step of positioning the second nut (4) on the body (11) of the base (1) so that the groove (115) for forming the axial stop (14) is opposite the internal groove (414).

11. A method of changing a drainage tube (3) of a casing according to one of claims 1 to 6, comprising a step of unscrewing the second nut (4), a step of changing the drainage tube (3) with another drainage tube (3) and a step of connecting by screwing the second nut (4) onto a threaded surface of the connecting head (31) or the body (11) of the base (1) to compress the internal connecting surface (13) to the external connecting surface (313) of the other drainage tube (3) connecting the channel (110) of the base (1) to the discharge conduit (30) of the other drainage tube (3).

Images