Assembly for Turbine Engine

- SAFRAN AERO BOOSTERS SA

An assembly for a turbine engine includes an upstream section and a downstream section, each having an annular row of semi-cylindrical radial recesses and a plurality of flanges positioned between two circumferentially adjacent recesses for holding the two sections together. The recesses form a cylindrical opening when the two sections are assembled. The openings receive pivot sections of variable stator vanes.

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Description

This application claims priority under 35 U.S.C. § 119 to Belgium Patent Application No. 2018/5242, filed 10 Apr. 2018, titled “Assembly for Turbine Engine,” which is incorporated herein by reference for all purposes.

BACKGROUND 1. Field of the Application

The present application relates to the field of axial turbine engines or turbomachines and more particularly aircraft turbojets. More specifically, the present application relates to the design of an assembly for a compressor provided with variable stator vanes.

2. Description of Related Art

Document FR 2565297 A1 describes a gas turbine compressor stator. The stator vanes are orientable around their axis by means of a connecting rod which is screwed to each vane head. Openings are provided in the ferrule to receive the heads of the vanes with a sleeve. A flange that closes the openings to enclose the vane heads in the openings. The sleeve and the heads of the vanes are recessed to cooperate with a bolt to maintain radially the vane in the opening.

This design is complex because it involves a large number of parts and the assembly of such a stator is therefore tedious.

Although great strides have been made in the area of assemblies for compressors having variable stator vanes, many shortcomings remain.

DESCRIPTION OF THE DRAWINGS

FIG. 1 represents an axial turbomachine according to the present application;

FIG. 2 is a diagram of a turbomachine compressor with an assembly according to the present application;

FIGS. 3 and 4 show respectively the head of a vane and a bottom view of the connecting rod;

FIG. 5 illustrates a partial view from above of the arrangement of the two sections;

FIGS. 6 and 7 are sectional views of the arrangement of the head of the vane with a welded rod;

FIG. 8 is a section of a vane with an integral rod;

FIG. 9 is a partial isometric view of the arrangement of the two sections; and

FIG. 10 illustrates a partial sectional view of the compressor.

 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present application aims to solve at least one of the problems posed by the prior art. The present application also aims to provide a simpler and more compact design, allowing easier assembly of variable stator vanes. The present application also aims to provide a lightweight solution, reliable and easy to produce.

The present application relates to an assembly for an aircraft turbine engine, comprising: an annular row of stator vanes each with an airfoil and a head having a pivot section; an actuator for pivoting the vanes, the actuator comprising a ring and connecting rods connecting the ring to each of the vanes; an outer shroud comprising an upstream section and a downstream section, both comprising an internal guiding surface for the gas flow of the turbine engine, and being axially in contact with each other, the upstream and the downstream sections comprising, each: an annular row of recesses having a semi-cylindrical shape; and at least one flange positioned between two circumferentially adjacent recesses of the annular row of recesses; the recesses of the upstream section being arranged radially and circumferentially in correspondence with the recesses of the downstream section so as to form an annular row of openings receiving the pivot sections of the vanes, each flange of the at least one flange of the upstream section being fixed to a flange of the at least one flange of the downstream section, the head of each of the vanes having a radial outer portion on the pivot section, the outer radial portion extending circumferentially and/or axially of a length which is greater than the diameter of the respective opening; the upstream and downstream sections being provided with an annular row of radial thickened portions or bosses within which the recesses are formed; the radial thickened portions or bosses being an annular row being interconnected to each other by the flanges.

Thus, the recesses and the flanges of the sections are arranged to allow the assembling of the sections to one another via the flanges, the recesses of the sections being adapted to be brought together to form cylindrical openings when the two sections are assembled.

According to an embodiment, the downstream section comprises a seat for receiving the actuator, the seat comprising a cylindrical surface.

According to an embodiment, the cylindrical surface defines a diameter and downstream of the seat, the downstream section does not extend radially of more than said diameter.

According to an embodiment, a flange of the at least one flange is arranged between two circumferentially neighboring recesses of the respective annular row of recesses of the upstream and the downstream section.

According to an embodiment, the flanges extend circumferentially from one recess to the adjacent recess. Thus, the flange extends circumferentially completely from one recess to the neighboring recess of the two circumferentially neighboring recesses.

According to an embodiment, each of the at least one flange comprises two through-holes for receiving screws, each flange having a circumferential length between two neighboring recesses and the through-holes being at a distance from one of the two neighboring recesses that is less than a quarter of the circumferential length of the flange.

According to an embodiment, the bosses have an external truncated surface.

According to an embodiment, the upstream section comprises a fixation flange at its axial upstream end for assembling the upstream section to a fan casing or a de-icing nozzle. Alternatively or complementarily, the downstream section comprises a fixation flange at its axial downstream end for assembling the downstream section to a casing.

According to an embodiment, the assembly further comprises a third section with semi-cylindrical recesses, the third section being connected to the downstream section and the recesses of the third section forming openings with additional semi-cylindrical recesses provided at the downstream end of the downstream section.

According to an embodiment, the connecting rod is integral with the vane, or is welded to the head of the vane. “integral” is intended to mean “made in one piece”, “from one raw bloc of material”.

According to an embodiment, the actuator comprises pads in radial contact with a cylindrical surface of one of the sections.

According to an embodiment, the flanges radially overlap the ring and are axially distant from it.

The present application also relates to an assembly for an aircraft turbine engine, comprising: an annular row of stator vanes each with an airfoil and a head having a pivot section; an actuator for pivoting the vanes, the actuator comprising a ring and being connected to each vanes through connecting rods; an outer shroud comprising an upstream section and a downstream section, both comprising an internal guiding surface for the gas flow of the turbine engine, and being axially in contact with each other, the upstream and the downstream sections comprising, each: an annular row of recesses having a semi-cylindrical shape; and at least one flange positioned between two circumferentially adjacent recesses of the annular row of recesses; the recesses of the upstream section being arranged radially and circumferentially in correspondence with the recesses of the downstream section so as to form an annular row of openings receiving the pivot sections of the vanes, each flange of the at least one flange of the upstream section being fixed to a flange of the at least one flange of the downstream section, the head of each of the vanes having a radial outer portion on the pivot section, the outer radial portion extending circumferentially and/or axially of a length which is greater than the diameter of the respective opening, the outer radial portion comprising the connecting rods; the airfoil of each vane having a leading edge and a trailing edge, the pivot section having a diameter that is smaller than the distance between the leading edge and the trailing edge; and wherein the radial outer portion, the pivot section and the airfoil are integrally formed.

The present application also relates to an assembly for an aircraft turbine engine, comprising: an annular row of stator vanes each with an airfoil and a head having a pivot section; an actuator for pivoting the vanes, the actuator comprising a ring and connecting rods connecting the ring to each of the vanes; an outer shroud comprising an upstream section and a downstream section, both comprising an internal guiding surface for the gas flow of the turbine engine, and being axially in contact with each other, the upstream and the downstream sections comprising, each: an annular row of recesses having a semi-cylindrical shape; and at least one flange positioned between two circumferentially adjacent recesses of the annular row of recesses; the recesses of the upstream section being arranged radially and circumferentially in correspondence with the recesses of the downstream section so as to form an annular row of openings receiving the pivot sections of the vanes, each flange of the at least one flange of the upstream section being fixed to a flange of the at least one flange of the downstream section, the head of each of the vanes having a radial outer portion on the pivot section, the outer radial portion extending circumferentially and/or axially of a length which is greater than the diameter of the respective opening; wherein the downstream section comprises a cylindrical surface and the ring is provided with pads in radial contact with the cylindrical surface; and wherein each of the flange overlaps radially the ring, and each of the flange is axially separated from the ring.

All the features of the embodiments can be combined with all the features of the other embodiments, according to all possible technical combinations, unless otherwise not explicitly mentioned.

The present application proposes a specific geometry that allows to assemble the variable orientation vanes without the need to mount each of the connecting rods once the vane mounted. When the compressor comprises about fifty vanes per row, the design proposed in the present application results in substantial gain in mounting time. In addition, this design allows the mounting of a one-piece ring (a 360° ring) that is compact and light.

In the following description, the terms “internal” and “external” refer to a positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are in reference to the direction of the air flow in the turbomachine.

FIG. 1 is a simplified representation of an axial turbomachine. It is in this case a double-flow turbojet engine. The turbojet engine 2 comprises a first compression level, called a low-pressure compressor 4, a second compression level, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power transmitted by the turbine 10 via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. The latter comprise several rows of rotor vanes associated with rows of stator vanes. The rotation of the rotor about its axis of rotation 14 thus makes it possible to generate an air flow and to compress it progressively until it reaches the combustion chamber 8.

A fan 16 is coupled to the rotor 12 via a gear train 13, and generates a flow of air which splits into a primary stream 18 passing through the various aforementioned levels of the turbomachine, and a secondary flow 20 passing through an annular duct (partially shown) along the machine to then join the primary flow at the turbine outlet.

The secondary flow can be accelerated so as to generate a thrust reaction for the flight of an aircraft. The primary 18 and secondary 20 streams are annular and coaxial flows arranged one into the other.

FIG. 2 is a sectional view of a compressor of an axial turbomachine such as that of FIG. 1. The flow can be transonic. The compressor may be a low-pressure compressor 4. The rotor 12 comprises several rows of rotor vanes 24, in this case three. It may be a bladed monobloc drum, or it may include vanes mounted via dovetail attachments.

The low-pressure compressor 4 comprises a plurality of stator vanes rows, in this case four, which each contain a row of stator vanes 26. Some stator vanes may be adjustable in orientation, also called variable stator vanes. The stator vanes rows are associated with the fan 16 or with a row of rotor vanes to straighten the air flow, so as to convert the speed of the flow pressure, including static pressure.

A de-icing nozzle 22 can be mounted on a housing that supports a row of stator inlet vanes 28.

The stator vanes 26 extend essentially radially from an outer shroud 30 to an inner shroud 32. The vanes 26 can be attached to the outer shroud 30 by means of pins or axles. The shroud 30 defines an inner surface 29 which guides the flow of air. According to the present application, the shroud 30 is composed of several axial sections.

The vanes 26 comprise a pivot section 34 in the form of a cylindrical pin which is received in a radial opening of the outer shroud 30. A connecting rod 36 integral with the pivot section and pivoting about the axis of the pivot section 34 makes it possible to maneuver the rotation of the vane. Actuators 40 of the connecting rod 36 are schematically shown and will be described later.

FIGS. 3 and 4 illustrate a known example of connection between the head of a vane 26 and the outer shroud 30. The vane 26 comprises an airfoil 42 having a leading edge 44 and a trailing edge 46. The head of the vane 26 may include a shoulder 48 for centering and positioning the vane 26 in the shroud 30 and a groove for receiving a seal. In the known embodiments, the connecting rod 36 for actuating the pivoting of the vane is fixed by a nut 50 on a threaded portion 52 of the head of the vane. A centering chamfer 54 may be provided at the end of the pivot section 34.

The head of the vane is received at a location of extra thickness of the shroud 30, which may be in the form of a boss 33.

The connecting rod 36 comprises a conical opening 60 corresponding to the chamfer 54, a body 62 and a lug 64. As shown in FIG. 4, which is a view from below of the connecting rod 36, the opening 60 may comprise a groove 66 for receiving a pin and thus ensures a common rotation of the vane 26 and the rod 36. The rod 36 also comprises a hole 68 to be connected to an actuating member (described in FIG. 10). In this example, the outer shroud 30 has an opening receiving the pivot section 34. The pivot section 34 is inserted into the hole from below (in the direction of FIG. 3), then the rod 36 is screwed to the thread 52.

FIGS. 5 to 7 show a first embodiment of the connection between the vane 26 and the outer shroud 30 according to the present application.

FIG. 5 shows a partial top view of the assembly according to the present application. FIG. 5 references the directions VI and VII whose sectional views are illustrated in FIGS. 6 and 7 respectively.

An upstream section 130 and a downstream section 230 form, together, the shroud. Each of the sections comprises a tubular wall 131, 231 defining an inner guide surface 129, 229 and an annular series of recesses 132, 232, in the form of half a cylinder, formed in bosses 133, 233. The two recesses 132; 232 form the opening 31 which receives the head of the vane. The two sections 130, 230 are assembled via screwed elements which maintain two flanges 134, 234 adjacent together. The flanges 134, 234 may extend from a boss to the circumferentially adjacent boss. FIG. 5 shows only one opening.

FIG. 6 is a section in the plane VI: VI defined in FIG. 5.

The shroud comprises two adjacent axial sections 130, 230. Each of the two sections comprises a tubular wall 131, 231 and an annular row of recesses 132, 232 formed in the bosses 133, 233.

The rod 36 of this first embodiment is welded to the head of the vane. This is done before mounting the vane in the shroud. As the opening 31 results from the combination of the two sections 130, 230, the pivot section 34 can be positioned in a recess 132, 232 of one of the sections despite the size of the rod which is greater than the diameter of the opening 31, then the other section is fixed to embed the pivot section 34 in the opening 31.

The rod 36 may have a shape similar to that of FIG. 4, potentially without groove as it becomes unnecessary thanks to the weld.

FIG. 7 shows a view along the plane VII: VII defined in FIG. 5. This view shows the assembly of the two flanges 134, 234 by means of a bolt 35. Indeed, the flanges 134, 234 have through-holes 135, 235 for assembling the shroud sections to one another by screwed elements 35. In the background in FIG. 7 one can see the bosses 133, 233.

FIG. 8 shows another embodiment. As opposed to FIGS. 6 and 7, the connecting rod 36 is here not welded to the pivot section 34, but the whole of the vane (airfoil, pivot section, connecting rod) is made in one piece. For example, the connecting rod can be forged or molded with the rest of the vane. The, functional surfaces (pivot section, extrados/intrados) are then machined. In the same way as for the example of FIGS. 6 and 7, it is the two-part design of the openings of the shroud which makes it possible to provide such a one-piece vane with its connecting rod.

FIG. 9 represents a partial isometric view of the shroud 30. In particular, the one can see some of the bosses 133, 233 as well as flanges 134, 234 and their through-holes (only the holes 235 of the downstream section 230 are visible). The flanges can completely connect each of the bosses 133, 233 to the directly neighboring boss. The upstream section 130 comprises a flange 136 which makes it possible to connect the shroud to the nozzle of the compressor. The downstream portion 230 comprises a support surface, preferably a cylindrical surface 237 for guiding the pads of the synchronizing ring 72 (see FIG. 10).

In this example, the flanges 134, 234 rise above the tubular wall 131, 231 of a height equivalent to that of the bosses 133, 233. Alternatively, the height of the bosses 133, 233 may be different from the height of the flanges 134, 234.

The upstream and downstream sections may have axial centering pins, particularly at the flanges to help centering the position of the sections while they are being assembled. For example, axial pins provided in one or more of the flanges 134 can cooperate with corresponding axial openings in one or more of the flanges 234.

FIG. 10 shows a section of the compressor. The shroud made of the two sections 130, 230 is fixed to the support housing of the de-icing nozzle which carries the stator inlet vanes 28 via the upstream flange 136. A downstream flange 236 is provided on the downstream section.

The actuating mechanism 40 of the pivoting vane comprises a pin 70 which is received in a distal opening of the rod 36 (equivalent to the opening 68 of the rod of FIG. 4). The pin 70 passes through a ring 72 and ends with a pad 74. The pad 74 rests on the cylindrical surface 237 of the downstream section 230. The cylindrical surface 237 ends upstream by a projection which limits the movement of the pad 74 axially. The projection and the cylindrical surface 237 form a seat for the pad 74. The ring 72 cooperates with as many pins 70 as connecting rods 36. The ring 72 can be pivotally actuated about the axis 14 by appropriate means such as for example a toothed wheel cooperating with a rack provided on the ring 72. The pivoting of the ring 72 causes a corresponding movement of the pins 70 along the surface 237. This results in the rotation of the rod 36 and of the vane 26 around the axis 38.

The ring 72 is also called synchronizing ring, operating ring, actuating ring or control ring.

The general shape of the downstream section 230 allows the mounting of the ring 72 and pins 70. In the example illustrated in FIG. 10, the flange 236 has an outer diameter which is substantially smaller than the inner diameter of the ring 72, thus allowing the pins 70 with their pads 74 to be inserted into the ring 72 before the assembly (ring 72, pins 70 and pads 74) is slid axially upstream to be mounted on the downstream section 230.

For the assembly of the sections, the following steps are followed: the pivot sections 34 of the vanes are inserted into the recesses 232, then the upstream section is brought to enclose the pivot sections 34 in the openings 31 thus formed. The flanges 134, 234 are then fixed to each other. Then the actuating pins 70 carried by the synchronizing ring 72 can be assembled to the connecting rods 36. Alternatively, the fixing of the pins 70 to the rods 36 can take place before the upstream section 130 is positioned in contact with the downstream section 230. Also, the ring 72 can be inserted around the downstream section 230 before the vanes 26 are brought into the recesses 232.

The embodiment described here has two sections 130 and 230 but one or more additional sections may be provided and assembled in the same way, each of the sections having an annular row of recesses facing the recesses of the adjacent section to form openings receiving vane heads which may or may not be of variable orientation.

Claims

1. An assembly for an aircraft turbine engine, comprising:

an annular row of stator vanes each with an airfoil and a head having a pivot section;
an actuator for pivoting the vanes, the actuator comprising: a ring and connecting rods connecting the ring to each of the vanes;
an outer shroud comprising an upstream section and a downstream section, both comprising an internal guiding surface for the gas flow of the turbine engine, and being axially in contact with each other, the upstream and the downstream sections comprising, each: an annular row of recesses having a semi-cylindrical shape; and at least one flange positioned between two circumferentially adjacent recesses of the annular row of recesses;
the recesses of the upstream section being arranged radially and circumferentially in correspondence with the recesses of the downstream section so as to form an annular row of openings receiving the pivot sections of the vanes;
each flange of the at least one flange of the upstream section being fixed to a flange of the at least one flange of the downstream section;
the head of each of the vanes having a radial outer portion on the pivot section, the outer radial portion extending circumferentially and/or axially of a length which is greater than the diameter of the respective opening;
the upstream and downstream sections being provided with an annular row of radial thickened portions or bosses within which the recesses are formed; and
the radial thickened portions or bosses being an annular row being interconnected to each other by the flanges.

2. The assembly according to claim 1, wherein the downstream section comprises:

a seat for receiving the actuator, the seat comprising: a cylindrical surface.

3. The assembly according to claim 2, wherein the cylindrical surface defines a diameter and downstream of the seat, the downstream section does not extend radially of more than said diameter.

4. The assembly according to claim 1, wherein a flange of the at least one flange is arranged between two circumferentially neighboring recesses of the respective annular row of recesses of the upstream and the downstream section.

5. The assembly according to claim 4, wherein the flange extends circumferentially completely from one recess to the neighboring recess of the two circumferentially neighboring recesses.

6. The assembly according to claim 1, wherein each of the at least one flange comprises two through-holes for receiving screws, each flange having a circumferential length between two neighboring recesses and the through-holes being at a distance from one of the two neighboring recesses that is less than a quarter of the circumferential length of the flange.

7. The assembly according to claim 1, wherein the bosses have an external truncated surface.

8. The assembly according to claim 1, wherein the upstream section comprises a fixation flange at its axial upstream end for assembling the upstream section to a fan casing or a de-icing nozzle.

9. The assembly according to claim 1, further comprising a third section with semi-cylindrical recesses, the third section being connected to the downstream section and the recesses of the third section forming openings with additional semi-cylindrical recesses provided at the downstream end of the downstream section.

10. An assembly for an aircraft turbine engine, comprising:

an annular row of stator vanes each with an airfoil and a head having a pivot section;
an actuator for pivoting the vanes, the actuator comprising a ring and being connected to each vanes through connecting rods;
an outer shroud comprising an upstream section and a downstream section, both comprising an internal guiding surface for the gas flow of the turbine engine, and being axially in contact with each other, the upstream and the downstream sections comprising, each: an annular row of recesses having a semi-cylindrical shape; and at least one flange positioned between two circumferentially adjacent recesses of the annular row of recesses;
the recesses of the upstream section being arranged radially and circumferentially in correspondence with the recesses of the downstream section so as to form an annular row of openings receiving the pivot sections of the vanes;
each flange of the at least one flange of the upstream section being fixed to a flange of the at least one flange of the downstream section;
the head of each of the vanes having a radial outer portion on the pivot section, the outer radial portion extending circumferentially and/or axially of a length which is greater than the diameter of the respective opening, the outer radial portion comprising the connecting rods; and
the airfoil of each vane having a leading edge and a trailing edge, the pivot section having a diameter that is smaller than the distance between the leading edge and the trailing edge; and wherein the radial outer portion, the pivot section and the airfoil are integrally formed.

11. An assembly for an aircraft turbine engine, comprising:

an annular row of stator vanes each with an airfoil and a head having a pivot section;
an actuator for pivoting the vanes, the actuator comprising a ring and connecting rods connecting the ring to each of the vanes;
an outer shroud comprising an upstream section and a downstream section, both comprising an internal guiding surface for the gas flow of the turbine engine, and being axially in contact with each other, the upstream and the downstream sections comprising, each: an annular row of recesses having a semi-cylindrical shape; and at least one flange positioned between two circumferentially adjacent recesses of the annular row of recesses;
the recesses of the upstream section being arranged radially and circumferentially in correspondence with the recesses of the downstream section so as to form an annular row of openings receiving the pivot sections of the vanes;
each flange of the at least one flange of the upstream section being fixed to a flange of the at least one flange of the downstream section;
the head of each of the vanes having a radial outer portion on the pivot section, the outer radial portion extending circumferentially and/or axially of a length which is greater than the diameter of the respective opening;
wherein the downstream section comprises a cylindrical surface and the ring is provided with pads in radial contact with the cylindrical surface; and
wherein each of the flange overlaps radially the ring, and, each of the flange is axially separated from the ring.
Patent History
Publication number: 20190309650
Type: Application
Filed: Apr 9, 2019
Publication Date: Oct 10, 2019
Applicant: SAFRAN AERO BOOSTERS SA (Herstal)
Inventor: Morgan Vyvey (Moissy-Cramayel)
Application Number: 16/379,327
Classifications
International Classification: F01D 17/16 (20060101); F01D 9/04 (20060101); F01D 5/14 (20060101);