FR3140116A1 - VARIABLE PITCH BLADE BLOWER WITH IMPROVED MOUNTING DEVICE - Google Patents

Abstract

The invention relates to a fan (10) for an aircraft turbomachine test bench comprising: - at least one blade (12) secured to a pivot (13), - a fan ring (11) (10) ) comprising two coaxial annular elements (18.1, 18.2) fixed to one another and defining between them at least one housing (17) for mounting the pivot (13), - a support plate (27) intended to be plated against an axial end face of one of the annular elements (18.1, 18.2), - at least one nut (31) mounted with clearance on a base (32), - said base (32) being fixed on the support plate (27), - at least one assembly screw (50) being inserted inside a first through fixing hole (51) made in the first annular element (18.1) and a second fixing hole ( 52) through made in the second annular element (18.2) so as to cooperate with the nut (31). Figure 6

Description

VARIABLE PITCH BLADE BLOWER WITH IMPROVED MOUNTING DEVICE

The present invention relates to a variable-pitch bladed blower with an improved mounting device.

In a manner known per se, an aircraft turbomachine comprises a turbomachine fan which compresses the air entering the engine. A part of this air constitutes the primary flow circulating in a primary flow space having a primary vein, and the other part of this air constitutes the secondary flow circulating in a secondary flow space having a secondary vein. The primary flow passes through a low pressure compressor attached to the fan, through a high pressure compressor, through the combustion chamber, through the high pressure turbine and, finally, through the low pressure turbine before being ejected. The secondary flow bypasses the hot part of the turbomachine.

The fan includes a ring and a plurality of blades extending radially outward from the ring. The ring can be formed by two coaxial annular elements delimiting housings for blade pivots.

In order to determine, during a test phase, an angular position of the blades optimizing the entry of the air flow inside the primary flow space, it is known to use a wedge system. variable, as described in document FR3111161.

This system comprises clamping flanges capable of taking a loosened state in which the flanges allow rotation of the blade pivots inside the ring housings and a locked state in which the clamping flanges immobilize the blade pivots. blade inside the ring housings to maintain the blades in a desired angular position during a fan test phase.

The assembly of the annular elements and the clamping flanges is carried out by means of fixing holes made in the annular elements. These fixing holes are intended to receive corresponding fixing members, such as screws.

However, there are disparities in the positioning of the fixing holes in relation to the axis of the annular rings due to machining inaccuracies. These disparities are likely to cause discrepancies between the parts on the external face of the ring. This disrupts the air flow entering the primary vein and therefore distorts the simulation results. In addition, the production of threads weakens the mechanical strength of the annular elements having thin thicknesses.

The invention aims to remedy the aforementioned drawbacks by proposing a fan for an aircraft turbomachine test bench comprising:

- at least one blade secured to a pivot,

- a fan ring comprising two coaxial annular elements fixed to one another and defining between them at least one pivot mounting housing,

- a support plate having an annular shape intended to be pressed against an axial end face of one of the annular elements,

- at least one nut mounted with clearance on a base,

- said base being fixed on the support plate,

- at least one assembly screw of the annular elements being inserted inside a first through fixing hole made in the first annular element and a second through fixing hole made in the second annular element so as to cooperate with the nut.

The invention thus makes it possible, thanks to the tightening nuts mounted with clearance on the support plate, to adapt to dimensional variations of the fixing holes made in the annular elements. The invention thus guarantees correct relative positioning between the different components of the fan, thus optimizing the continuity of the primary flow of the turbomachine. In addition, as the fixing of the assembly screw is carried out by means of the added nut, the fixing holes made in the annular elements can be smooth holes which, unlike tapped holes, do not alter the structure annular elements.

According to one embodiment of the invention, at least one mounting screw of a clamping flange is inserted inside a through fixing hole made in one of the annular elements and a through fixing hole made in the clamping flange so as to cooperate with a second nut mounted with clearance on a second base fixed on the support plate.

According to one embodiment of the invention, the base is riveted to the support plate.

According to one embodiment of the invention, one end of the nut is extended by a base.

According to one embodiment of the invention, the base comprises folded portions each defining a retaining space with clearance for one edge of the base.

According to one embodiment of the invention, the support plate is mounted centered in relation to the ring.

According to one embodiment of the invention, the support plate comprises a central opening allowing the passage of a centering surface of one of the annular elements.

According to one embodiment of the invention, the support plate comprises a plurality of fixing zones each comprising several nuts and several bases, the fixing zones being angularly spaced regularly along a circumference of the support plate.

According to one embodiment of the invention, the support plate comprises notches, each notch extending between two consecutive adjacent fixing zones.

According to one embodiment of the invention, the support plate is made of a metallic material, such as steel.

The present invention will be better understood and other characteristics and advantages will appear further on reading the detailed description which follows including embodiments given by way of illustration with reference to the appended figures, presented by way of non-limiting examples, which may be used to complete the understanding of the present invention and the presentation of its realization and, where appropriate, contribute to its definition, on which:

Figures 1 and 2 are front and rear perspective views of a turbomachine fan according to the invention provided with variable pitch blades;

There is a partial perspective view of a blower according to the invention provided with a pivot inserted inside a housing of an annular element and held in its angular position by means of a clamping flange;

There is a detailed perspective view of clamping nuts mounted on bases intended to be riveted onto a support plate according to the invention;

There is a schematic representation illustrating the clearance mounting of a nut on a corresponding base;

There is a schematic representation illustrating the mounting of an assembly screw between the two annular elements cooperating with a nut mounted with clearance on the support plate according to the invention;

There is a schematic representation illustrating the mounting of a screw for fixing a clamping flange cooperating with a nut mounted with clearance on the support plate according to the invention.

It should be noted that, in the figures, the structural and/or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

Figures 1 and 2 show a fan 10 for an aircraft turbomachine test bench comprising a ring 11 having an axis X and a plurality of blades 12. The blades 12 extend radially towards the outside of the ring 11 along their axis Y. The blades 12 are distributed angularly in a regular manner along a circumference of the ring 11.

A blade 12 is integral with a pivot 13 having a generally cylindrical shape. For this purpose, a blade 12 has a blade root 15 inserted in a groove 16 of complementary shape formed in a corresponding pivot 13. The complementary shapes of the blade root 15 and the groove 16 may in particular be dovetail, hammer-type, or fir-tree shapes. Any other shape suitable for the application can be used.

The ring 11 comprises two coaxial annular elements 18.1, 18.2 fixed to one another and defining between them housings 17 for mounting the pivots 13. We distinguish, with reference to a direction of circulation of the air flow generated by the fan 10 in operation, an upstream annular element 18.1 and a downstream annular element 18.2. Thus, a portion of a housing 17 is delimited by the upstream annular element 18.1 and a complementary portion of the housing 17 is delimited by the downstream annular element 18.2.

A stop wall 19 is inserted inside a circumferential groove 21 made in the pivot 13. A first portion of the stop wall 19 is provided in the upstream annular element 18.1 and a second portion of the stop wall 19 is provided in the downstream annular element 18.2. The stop wall 19 ensures radial retention of the pivot 13 inside the housing 17.

Furthermore, as can be seen in particular on the , a clamping flange 23 is able to take a loosened state in which the clamping flange 23 allows rotation of a pivot 13 and therefore of the corresponding blade 12 inside a housing 17 of the ring 11 and a locked state in which the clamp 23 immobilizes the pivot 13 corresponding to the interior of the housing 17 of the ring 11 to maintain the blades 12 in a desired angular position during a test phase of the fan 10 .

The clamp 23 has a bridge shape, in particular an elongated U shape. The clamp 23 is provided with two fixing holes 24 each arranged at one end of the clamp 23. Each fixing hole 24 is intended to receive a fixing member 55, such as a screw.

In order to allow access to the fixing members 55 of the clamping flanges 23, the upstream annular element 18.1 has at least one through window 25. The through window 25 allows the passage of a tool intended to cooperate with an imprint of the members fixing device 55. A window 25 can be constituted by an opening sized to allow access to two adjacent fixing members 55 used for fixing two adjacent clamping flanges 23.

Furthermore, a support plate 27 visible on the is intended to be pressed against an axial end face 28 of an annular element, in this case the downstream annular element 18.2. Alternatively, the support plate 27 can be pressed against an axial end face 28 of the upstream annular element 18.1. The support plate 27 has an annular shape with radial orientation relative to the axis support 27 is made of a metallic material, such as steel.

The support plate 27 comprises a plurality of fixing zones 30 each comprising several nuts 31 and several bases 32 described in more detail below. The fixing zones 30 are spaced angularly apart from each other in a regular manner along a circumference of the support plate 27. In order to limit the mass of the assembly, the support plate 27 has notches 33. Each notch 33 extends between two consecutive adjacent fixing zones 30. There is thus an alternation of fixing zones 30 and notches 33 following a circumference of the support plate 27.

The support plate 27 is mounted centered in relation to the ring 11. For this purpose, the support plate 27 has a central opening 35 allowing the passage of a centering surface 36 coming from the annular element 18.2. The centering surface 36 consists of an annular wall having an axial orientation relative to the axis X.

As can be seen in Figures 4 and 5, a plurality of nuts 31 are mounted with play on bases 32 fixed on the support plate 27. For this purpose, one end of a nut 31 is extended by a base 38. The base 38 has the shape of a rectangular or square plate. The plate may have clearances on certain sides.

A base 32 comprises folded portions 41 each defining a space 42 for retaining with play for one edge of a base 38 of the nut 31. The spaces 42 for retaining with play are configured to allow movement of the nut 31 in a radial plane relative to the axis of the fan 10. The folded portions 41 extend longitudinally along two opposite sides of a base 38. The bases 32 are preferably made of a metallic material, in particular steel.

Each base 32 is preferably riveted to the support plate 27. In the example shown, the base 32 has the shape of an elongated plate provided at its ends with two lugs each comprising an opening 43 for the passage of a rivet 44. during the riveting operation, a rivet 44 is inserted inside an opening and its heads 47 are deformed to ensure the assembly of the base 32 on the support plate 27. Once the riveting operation carried out, one of the heads 47 of the rivet 44 is ground so that each rivet 44 has a single head 47. Preferably, as can be seen in Figures 6 and 7, the head 47 of the rivet 44 which is ground is that located on the side of the face of the support plate 27 bearing against the annular element 18.2. Alternatively, the base 32 can be fixed on the support plate 27 by welding, gluing, or any other fixing technique adapted to the application.

As illustrated in the , at least one screw 50 for assembling the annular elements 18.1, 18.2 is inserted inside a first through fixing hole 51 made in the upstream annular element 18.1 and a second through fixing hole 52 made in the downstream annular element 18.2 so as to cooperate with a nut 31. The assembly screw 50 is screwed inside the nut 31 mounted with clearance on the support plate 27 so as to absorb the dimensional variations of the holes fixing 51, 52 relative to the axis occurrence the upstream annular element 18.1. The first fixing hole 51 and the second fixing hole 52 are smooth holes. Preferably, a plurality of assembly screws 50 are used, spaced angularly apart in a regular manner and each cooperating with a nut 31 disposed in a fixing zone 30.

As illustrated in the , at least one screw 55 for mounting a clamping flange 23 is inserted inside a through fixing hole 56 made in the downstream annular element 18.2 and a through fixing hole 24 made in the flange tightening 23 so as to cooperate with a second nut 31 mounted with clearance on a base 32 fixed on the support plate 27. The fixing holes 24, 56 are smooth holes. Preferably, a plurality of mounting screws 55 are used angularly spaced apart from each other in a regular manner. Two screws 55 cooperate with two nuts 31 arranged in a corresponding fixing zone 30.

The assembly of the blower 10 for a test bench according to the invention is described below. The support plate 27 is arranged around the annular centering surface 36. The two annular elements 18.1, 18.2 are assembled by means of assembly screws 50 inserted inside the fixing holes 51, 52 and cooperating with a plurality of nuts 31. Each screw 50 is associated with a nut 31 located in a fixation zone 30.

The clamping flanges 23 are mounted using screws 55 inserted, via the windows 25, inside the fixing holes 24 of the clamping flanges 23 and the fixing holes 56 made in the downstream annular element 18.2 of so as to cooperate with corresponding nuts 31. Two screws 55 are associated with two nuts 31 located in a fixing zone 30.

An instrumented cone (not shown) carried by the ring 11 as well as the nacelle (not shown) are then installed on the machine.

In order to ensure angular adjustment of the blades 12, the instrumented cone is first dismantled. We then carry out a slight loosening of the flanges 23 in order to be able to modify the orientation of the blades 12 according to the desired angle. The blades 12 can be manipulated by hand or, where appropriate, automatically by a robot.

The flanges 23 are then tightened to maintain the blades 12 in the desired angular position. The instrumented cone can then be reinstalled before carrying out a new test.

The invention thus makes it possible to carry out a rapid modification of the setting of the blades 12 between two tests. The invention also makes it possible to have no interference with the aerodynamic flow of the primary vein. In addition, in the event of breakage of a blade 12, dismantling can be carried out in situ, which constitutes a significant saving of time. To this end, simply dismantle the cone and the upstream annular element 18.1. We can then change the modular "vane-pivot" assembly before reinstalling the flange 23 then the upstream annular element 18.1 as well as the instrumented cone. No dismantling of the nacelle is required.

Of course, the different features, variants and/or embodiments of the present invention can be associated with each other in various combinations as long as they are not incompatible or exclusive of each other.

Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that those skilled in the art may consider in the context of the present invention and in particular all combinations of the different modes of operation described above, which can be taken separately or in combination.

Claims (10)

Blower (10) for an aircraft turbomachine test bench comprising:
- at least one blade (12) secured to a pivot (13),
- a ring (11) of a fan (10) comprising two coaxial annular elements (18.1, 18.2) fixed to one another and defining between them at least one housing (17) for mounting the pivot (13),
characterized in that the blower (10) further comprises:
- a support plate (27) having an annular shape intended to be pressed against an axial end face of one of the annular elements,
- at least one nut (31) mounted with clearance on a base (32),
- said base (32) being fixed on the support plate (27),
- at least one screw (50) for assembling the annular elements (18.1, 18.2) being inserted inside a first through fixing hole (51) made in the first annular element (18.1) and a second through fixing hole (52) made in the second annular element (18.2) so as to cooperate with the nut (31). Blower according to claim 1, characterized in that at least one screw (55) for mounting a clamping flange (23) is inserted inside a through fixing hole (56) made in one of the elements annular (18.1, 18.2) and a through fixing hole (24) made in the clamping flange (23) so as to cooperate with a second nut (31) mounted with clearance on a second base (32) fixed on the support plate (27). Blower according to claim 1 or 2, characterized in that the base (32) is riveted to the support plate (27). Blower according to any one of claims 1 to 3, characterized in that one end of the nut (31) is extended by a base (38). Blower according to claim 4, characterized in that the base (32) comprises folded portions (41) each defining a retaining space (42) with clearance for one edge of the base (38). Blower according to any one of Claims 1 to 5, characterized in that the support plate (27) is mounted centered in relation to the ring (11). Blower according to claim 6, characterized in that the support plate (27) has a central opening (35) allowing the passage of a centering surface (36) of one of the annular elements (18.1, 18.2). Blower according to any one of claims 1 to 7, characterized in that the support plate (27) comprises a plurality of fixing zones (30) each comprising several nuts (31) and several bases (32), the zones of fixing (30) being spaced angularly regularly along a circumference of the support plate (27). Blower according to claim 8, characterized in that the support plate (27) comprises notches (33), each notch (33) extending between two consecutive adjacent fixing zones (30). Blower according to any one of claims 1 to 9, characterized in that the support plate (27) is made of a metallic material, such as steel.