TURBINE ENGINE FOOTPLATE

Description

technical field

[0001] The invention relates to the field of axial turbomachinery and more particularly to aircraft turbojets. More specifically, the invention relates to an assembly for an axial turbomachine, particularly for aircraft turbojets, the assembly comprising an annular row of steerable stator blades, a device for actuation of the blade pivoting and an external shell having a cylindrical surface forming a seat for the actuation device.

[0002] The invention also relates to a turbomachine equipped with such an assembly. Prior art

[0003] US patent 2016 / 0160675 describes an axial turbomachine with a specific arrangement of variable-angle stator blade journals within an external compressor shell. The blade pitch control system is located downstream of each blade. A connecting rod, designated 80, allows adjustment of the blade pitch. This connecting rod can be manipulated by a synchronizing ring to ensure that all blades in a given stage are oriented identically. The synchronizing ring is also called a control ring, operating ring, or control ring. Such a ring may sometimes be mounted directly on the external shell.

[0004] Such a design is possible in the system described in the document cited above, which includes several variable-pitch compression stages with an external ferrule extending over several of these stages. Such a ferrule is bulky. In a compressor with a shorter ferrule or fewer compression stages, such a mechanism is unnecessarily cumbersome.

[0005] EP 0 636 766 A1, US 4 130 375 A, GB 805 015 A, US 3 314 654 A and WO 2014 / 143445 A2 disclose further examples of steerable stator blade devices. Summary of the invention Technical problem

[0006] The invention aims to solve at least one of the problems posed by the prior art. The invention also aims to provide a simpler and more compact design, allowing for easier assembly of the variable-angle blades and the angle-control mechanism. The invention further aims to provide a lightweight solution. Technical solution

[0007] The invention relates to an assembly according to claim 1.

[0008] The term "ferrule" refers to a part that rotates approximately around an axis. Axial ferrule sections are portions of a ferrule.

[0009] Thus, the cylindrical surface surrounds the flanges and makes the whole thing more compact.

[0010] According to advantageous embodiments of the invention, the assembly may comprise one or more of the following features, taken individually or in all possible technical combinations: The tubular wall and flange of the first section form a T-shaped profile. The tubular wall and flange of the first section are made of a single piece of material. The ring can be in direct or indirect contact with the cylindrical surface. The assembly includes pads suitable for attachment to the ring and for contact with the cylindrical surface. The assembly includes sleeves, each comprising a tubular portion for cooperating with a rod or the ring, and a cylindrical or rectangular portion for cooperating with a pad. The assembly includes a plurality of screw-nut pairs, the flanges having holes through which the screws can pass to secure the sections together by bolting. The holes are axial and such that, once the assembly is complete, the nuts are parallel to the cylindrical surface.At least one of the flanges and / or the tube wall and / or the sections is / are made of a titanium, aluminum, or magnesium alloy and / or composite material. The first section is made from an assembly of two half-sections, each half-section comprising an annular row of semi-cylindrical radial half-orifices. The half-orifices are arranged so that each half-orifice of one half-section is axially and circumferentially matched with a half-orifice of the other half-section to form the annular row of radial orifices. The half-sections are joined using respective flanges positioned circumferentially between two adjacent half-orifices, each circumferential gap between two adjacent half-orifices containing one of the flanges.The flanges are sides extending perpendicularly to the axis of symmetry of the ferrule and having an axial thickness, the cylindrical surface extending axially over a length of more than three times the sum of the axial thicknesses of the two flanges.

[0011] The invention also relates to an axial turbomachine, in particular an aircraft turbojet, with a low-pressure compressor, a high-pressure compressor and an intermediate flow between the low-pressure compressor and the high-pressure compressor, notable in that the low-pressure compressor, the intermediate flow and / or the high-pressure compressor comprises / comprise an assembly as described above.

[0012] In an unclaimed embodiment, a method for assembling such an assembly using such a kit is defined, the method comprising the following steps: the introduction of the blade heads into the radial orifices of the first section; the assembly of the pads, rods and connecting rods to the ring; the assembly of a control rod to the head of each blade; the fixing, preferably by screwing, of the flanges of the two sections together.

[0013] According to an advantageous mode, the process includes a step of assembling the half-sections carried out after the step of assembling the connecting rods to the blades. Benefits provided

[0014] The invention proposes a specific geometry that is particularly compact. Furthermore, the positioning of the cylindrical surface above the flanges ensures good rigidity of the actuating device seat. Brief description of the drawings

[0015] THE Figures 1A and 1Brepresent an axial turbomachine; The figure 2 is a diagram of a turbomachine compressor according to the prior art; The figures 3 And 4 respectively show a compressor with a ferrule and an enlarged portion of the ferrule, according to the invention; The Figure 5 illustrates a sleeve that can be used in the assembly according to the invention; The figure 6 is a cross-section of a blade with a one-piece connecting rod used in a second embodiment of the invention; The figure 7 is a partial isometric view of the first section in this second embodiment. Description of the implementation methods

[0016] In the following description, the terms "internal" and "external" refer to positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the turbomachine's axis of rotation. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the main flow direction within the turbomachine.

[0017] There Figure 1AThis simplified diagram represents an axial turbomachine. It is a turbofan engine. The turbofan engine 2 comprises a first compression stage, called the low-pressure compressor 4, a second compression stage, called the high-pressure compressor 6, a combustion chamber 8, and one or more turbine stages 10. In operation, the mechanical power of the turbine 10, transmitted via the central shaft to the rotor 12, drives the two compressors 4 and 6. These compressors have several rows of rotor blades associated with rows of stator blades. The rotation of the rotor around its axis of rotation 14 generates an airflow and progressively compresses this air until it enters the combustion chamber 8.

[0018] An inlet fan commonly referred to as a fan or blower 16 is coupled to the rotor 12 via a gear train 17, and generates an airflow which splits into a primary flow 18 passing through the aforementioned different levels of the turbomachine, and a secondary flow 20 passing through an annular duct (partially shown) along the machine and then joining the primary flow at the turbine outlet.

[0019] The secondary flow can be accelerated to generate the thrust necessary for an aircraft to fly. The primary flow 18 and secondary flow 20 are coaxial annular flows nested within each other.

[0020] There figure 1B represents an axial turbomachine 2 with an alternative architecture to that of the Figure 1AThe same reference numbers represent the same elements. The difference between the two architectures is the presence of a housing 11 carrying the reduction gear 17, notably via radial arms (called "struts") 13. The radial arms 13 can be directly downstream of a row of stator blades 15.

[0021] In what follows, the illustrated implementation method relates to the architecture of the Figure 1A but all the technical features of the invention can also be provided on a turbomachine with an architecture according to the figure 1B .

[0022] There figure 2 is a cross-sectional view of a compressor in an axial turbomachine such as that of the figure 1with an external ferrule according to the state of the art. The compressor may be a low-pressure compressor. The rotor comprises several rows of rotor blades. It may consist of a one-piece bladed drum or one-piece bladed discs. Alternatively, it may include dovetail-mounted blades.

[0023] The low-pressure compressor 4 comprises several rectifiers, for example four, each containing a row of stator blades 26. Some of the stator blades may have adjustable pitch, also known as variable-pitch blades. The rectifiers are associated with a row of rotor blades to straighten the airflow, thereby converting the flow velocity into pressure, specifically static pressure.

[0024] A nozzle 22 which can have de-icing functions can be mounted on a housing which supports a row of inlet stator blades 28.

[0025] The stator blades 26 extend essentially radially from an outer shell 30 to inner rings 32. The blades 26 can be fixed to the outer shell 30 by means of shafts or trunnions 34. The shell 30 defines an internal surface 29 that guides the gas flow. The compressor may have several adjacent axial sections to form the shell 30.

[0026] In this example, the trunnion 34 is driven in pivoting by a connecting rod 36 around the axis 38 of the trunnion 34. The connecting rod 36 is fixed to the trunnion 34, for example by a nut.

[0027] The connecting rods of the annular row of blades 26 are all connected to a synchronizing ring 40 by means of rods 42.

[0028] The ring 40 rests on a cylindrical or conical surface 37.

[0029] There figure 3partially represents the compressor assembled from a set according to the invention. The numbers are incremented by 100 to designate technical characteristics corresponding to those of the figure 2 .

[0030] In comparison to the figure 2 The ferrule of the invention comprises a first section 130 and a second section 230. The sections describe an internal surface for guiding the gas flow 129, 229. The sections include respective flanges 131, 231 placed opposite each other for assembling the compressor.

[0031] The first section 130 has a tubular wall 132 defining an external cylindrical surface 137.

[0032] More details on this subject are given on the figure 4 which is an expansion of the area of ​​the figure 3 surrounded by dotted lines.

[0033] The blade 126 comprises a blade 142 having a leading edge 144 and a trailing edge 146. The blade head 126 may include a shoulder 148 for centering and positioning the blade 126 within the ferrule 130, as well as a groove for receiving a seal. The connecting rod 136 for pivoting the blade is secured by a nut 150 to a threaded portion 152 of the blade head. A centering chamfer 154 may be provided at the end of the trunnion 134.

[0034] The head of the awl is received at the right of an overthickness of the ferrule 130, which can be in the form of a boss 133.

[0035] The connecting rod 136 may include a conical orifice 160 corresponding to the chamfer 154, a body 162 and a leg 164. The orifice 160 may include a groove to receive a key and thus make the blade 126 and the connecting rod 136 rotationally fixed.

[0036] In this example, the tubular wall 132 is made of material along with the flange 131. Together they form a "T" profile. Alternatively, the tubular wall can be radially distant from the flange.

[0037] An axis 135 schematically represents the junction between the flanges 131, 231 which can be made by screwed elements.

[0038] The cylindrical surface 137 acts as a support for pads 166 carried by the ring 140.

[0039] A rod 168 provides the connection between the connecting rod 136 and the ring 140. A sleeve 170 provides the connection of the pads 166 to the rod 168 and / or to the ring 140.

[0040] The ring 140 is in the form of a solid ring or two half-rings, with a plurality of radial orifices penetrated by the rods 168. These orifices can be threaded.

[0041] Ring 140 may have annular grooves on its upstream and downstream face in order to optimize its weight without compromising its rigidity.

[0042] The synchronizing ring 140 cooperates with as many rods 168 as connecting rods 136 arranged annularly. The ring 140 can be pivotally actuated about the axis 114 by suitable means, such as a toothed wheel cooperating with a rack provided on the ring 140. The rack can be housed in one of the grooves of the ring 140. The pivoting of the ring 140 causes a corresponding displacement of the rods 168 along the surface 137, and these rods thus rotate the connecting rods 136 and the blades 126 about their axes 138.

[0043] The 166 pads can be directly connected to the 140 ring or to the 168 rod.

[0044] Alternatively, an intermediate sleeve 170 can be provided for each rod 168 and each skate 166.

[0045] Sleeve 170 is described on the Figure 5This includes a tubular portion 172 which can be threaded externally to be inserted into the ring 140 and / or internally to receive the rod 168. The sleeve also includes a rectangular portion 174 which allows the pad 166 to be held by gluing, shrink fitting or screwing - for example by means of a countersunk screw 180 inserted from below and whose head will be countersunk in the pad 166. The portion 174 can alternatively be cylindrical to accommodate a cylindrical pad.

[0046] In the example of Figures 4 and 5 The outer ferrule 130 has an opening 139 that receives the trunnion 134. The trunnion 134 is inserted into the opening 139 from below (in the direction of the figure 4 ), then connecting rod 136 is screwed in using thread 52.

[0047] THE figures 6 and 7show a different arrangement. These are described together in the following paragraphs. The reference numbers of the blade and connecting rod are indexed by 100 with respect to the embodiment of the figures 3 to 5 .

[0048] The blade 226 is a single piece with the connecting rod 236 and the orifice of the ferrule 130 receiving the journal 234 is made of two half-orifices (139.1, 139.2 on the figure 7 ).

[0049] Two half-sections 130.1 and 130.2 form the ferrule 130. Each of the half-sections 130.1, 130.2 comprises a tubular wall defining an internal guiding surface 129.1, 129.2 and an annular series of half-orifices 139.1, 139.2, formed in half-bosses 133.1, 133.2. The two half-orifices 139.1, 139.2 form the orifice 139 which receives the trunnion 234 of the blade 226. The two half-sections 130.1, 130.2 are assembled via screwed elements which hold two adjacent flanges 131.1, 131.2 together. The flanges 131.1 and 131.2 can extend circumferentially from one boss to the next. The connecting rod 236 is formed from the same material as the blade head. For example, the connecting rod can be forged or cast with the rest of the blade. The functional surfaces (trunk, upper / lower surfaces) are then machined. Alternatively, a welded assembly can be made. This is carried out before mounting the blade in the ferrule.Since the orifice 139 results from the combination of the two half-sections 130.1, 130.2, the trunnion 234 can be positioned in a half-orifice 139.1, 139.2 of the half-section 130.1 despite the dimension of the connecting rod which is greater than the diameter of the orifice 139, then the other half-section 130.2 is fixed to clamp the trunnion 234 in the orifice 139. The synchronizing ring fitted with its pads can be mounted on the second ferrule section before the blades are mounted in the half-orifices 139.1, 139.2.

[0050] There figure 7Figure 130 represents a partial isometric view of the ferrule 130 of this second embodiment. It shows, in particular, some of the bosses 133.1, 133.2, as well as the flanges 131.1, 131.2 and their assembly holes (only the holes 235 of the downstream half-section 130.2 are visible). The flanges can completely connect each of the bosses 133.1, 133.2 to the adjacent boss. The upstream half-section 130.1 includes a flange 131.3 that connects the ferrule to the compressor nozzle. The downstream half-section 130.2 includes the bearing surface 137 on the tubular wall 132, which forms a "T" profile with the flange 131.

[0051] In the illustrated examples, the surface 137 is presented as cylindrical but in an unclaimed embodiment it is also possible to provide any profile for the surface 137, in particular conical or with a profile complementary to that of the pads such as in particular an external groove allowing to guide pads equipped with a pin extending radially inwards.

Claims

1. Assembly for an axial turbomachine (2), in particular for an aircraft turbojet engine, the assembly comprising: - an annular row of stator vanes (126) each with an airfoil (142) and a radial head (134, 148, 154) containing a cylindrical trunnion (134); the vanes (126) being orientable by pivoting around the axis of the trunnion (138); - an actuating device (136, 140, 166, 168, 170) for pivoting the vanes (126) comprising a synchronization ring (140) and operating rods (136) connecting the synchronization ring (140) to each vane (126); - an outer shroud (130, 230) comprising a tubular wall and having an annular row of radial orifices (139) for receiving the heads (134, 148, 154) of the vanes (126); the shroud (130, 230) comprising two axially adjacent tubular sections (130, 230), the sections (130, 230) being assembled by means of respective flanges (131, 231), characterized in that the first section (130) comprises a cylindrical surface (137) coaxial with the section (130) and forms a seat for the actuating device (136, 140, 166, 168, 170), and in that the cylindrical surface (137) is an external surface of a tubular wall (132) axially overlapping the two flanges (131, 231).

2. The assembly of claim 1, characterized in that the tubular wall (132) and the flange (131) of the first section (130) form a "T"-shaped cross section.

3. The assembly of one of claims 1 or 2, characterized in that the tubular wall (132) and the flange (131) of the first section (130) are integrally made.

4. The assembly of one of claims 1 to 3, characterized in that it further comprises pads (166) fixed to the ring (140) and coming into contact with the cylindrical surface (137).

5. The assembly of the preceding claim, characterized in that it comprises sleeves (170), each of which comprising a tubular portion (172) for cooperating with a rod (168) or with the ring (140); and a rectangular portion (174) or cylindrical portion to cooperate with a pad (166).

6. The assembly of one of claims 1 to 5, characterized in that it comprises a plurality of screw-nut pairs, the flanges (131, 213) comprising orifices which can be traversed by the screws to maintain the sections (130, 230) fixed together by a screw-nut connection.

7. The assembly of the preceding claim, characterized in that the orifices are axially oriented and are such that the nuts are parallel to the cylindrical surface (137).

8. The assembly of one of claims 1 to 7, characterized in that at least one of the flanges (131, 231) and / or the tubular wall (132) and / or the sections (130, 230) is / are composed of an alloy of titanium, aluminium, or magnesium, and / or composite material.

9. The assembly of one of claims 1 to 8, characterized in that the first section (130) is constituted by an assembly of two half-sections (130.1, 130.2), each of the half-sections (130.1, 130.2) comprising an annular row of semicylindrical radial half-orifices (139.1, 139.2), the half-orifices (139.1, 139.2) being arranged to allow each of the half-orifices (139.1, 139.2) of a half-section (130.1, 130.2) to be brought into axial and circumferential correspondence with a half-orifice (139.1, 139.2) of the other half-section (130.1, 130.2) to form the annular row of radial orifices (139).

10. The assembly of the preceding claim, characterized in that the half-sections (130.1, 130.2) are assembled using respective half-section flanges (13.1, 131.2) positioned circumferentially between two adjacent half-orifices (139.1, 139.2), wherein each circumferential spacing between two adjacent half-orifices (139.1, 139.2) contains one of the respective half-section flanges (131.1, 131.2).

11. The assembly of one of claims 1 to 10, characterized in that the flanges (131, 231) are flanks extending perpendicular to an axis of symmetry (114) of the shroud and having an axial thickness (E1, E2), the cylindrical surface (137) extending axially over a length (L) of more than three times the sum of the axial thicknesses (E1, E2) of the two flanges (131, 231).

12. Axial turbomachine (2), in particular an aircraft turbojet, with a low-pressure compressor (4), a high-pressure compressor (6) and an intermediate passage between the low-pressure compressor (4) and the high compressor pressure (6), characterized in that the low-pressure compressor (4), the intermediate passage and / or the high-pressure compressor (6) comprises / comprise an assembly according to one of claims 1 to 11.