FR3107097A1 - Turbomachine assembly equipped with a screw fixing device, turbine and turbomachine comprising such an assembly - Google Patents

Abstract

Turbomachine assembly equipped with a screw, turbine and turbomachine fixing device comprising such an assembly One aspect of the invention relates to a turbomachine assembly extending around an axis (AA), comprising a first and a second part fixed by a fastening device (100), the fastening device comprising a risk screw (20, 30) housed in the first and second parts, and a first lateral screw (21, 31) and a second lateral screw (22 , 32) disposed circumferentially on either side of the risk screw (20, 30), the risk screw and the side screws each comprising a threaded rod (24) housed in an orifice passing through the first and the second parts and a screw head (23) mounted at one end of each threaded rod, said fixing device comprising a first retaining means (110) extending laterally between the first lateral screw and the second lateral screw, the first retaining means comprising : to a first lateral end, a first pin (112) which laterally encircles the head of the first lateral screw (21, 31), at a second lateral end, a second pin (113) which laterally encircles the head of the second lateral screw (22, 32), and between the two lateral ends, a central bearing which surrounds the head of the screw at risk (20, 30) transversely. Figure to be published with the abstract: Figure 3D

Description

Turbomachine assembly equipped with a screw fastening device, turbine and turbomachine comprising such an assembly

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a turbomachine assembly equipped with a screw fixing with retention of said screws. It also relates to a turbomachine turbine and a turbomachine comprising such an assembly.

The invention finds applications in the field of aeronautics and, in particular, in the field of turbomachines such as turbojets or turboprops.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

In the field of aeronautics, the rotating machines, or turbines, which are found in turbomachines, and in particular in turbojets and turboprops, generally comprise a plurality of parts assembled with each other by means in particular of screws. These assemblies can be made axially, by means of so-called axial fixing elements, such as axial screws, for example. They can also be made radially, using so-called radial fasteners, such as radial screws.

FIG. 1 represents an example of an axial assembly, in a rotating machine 10, in which the parts 11, 12 and 13 are fixed to each other by an axial screw 20. In an axial assembly such as that of FIG. , the axial screws 20 are generally dimensioned and calculated according to the thermomechanical constraints of the connection, such as for example the tightening torque, friction and thermal expansion. However, the rotating machine 10 may be required to operate in an extreme environment or conditions which may cause one or even more of the axial screws 20 to break.

Figure 2 shows an example of a radial assembly in which the parts 13 and 14 are fixed to each other by a radial screw 30. In a radial assembly such as that of Figure 2, the radial screw fasteners are not recommended because there is, in the more or less long term, a high risk of loosening of the radial screws during operation of the rotating machine, which can lead not only to disassembly of the parts initially assembled, but also to the ejection of the (or even the) radial screw outside the parts.

However, the breakage of one (or more) axial screw or the ejection of one (or more) radial screw can have serious consequences for the proper functioning of the rotating machine. In fact, not only are the parts initially assembled no longer correctly held together, which generally leads to a malfunction of the rotating machine, but in addition the ejected or broken screw leads to DOD (Domestic Object Damage, in terms Anglo-Saxon), i.e. damage caused by an engine part. Indeed, this broken or ejected screw turns into flying debris which, ingested at high speed, can cause a lot of damage within the rotating machine itself.

There is therefore a need for a fastening device for a turbine, reliable and easy to implement, which makes it possible to retain the screws.

To respond to the problems mentioned above of the consequences of the breakage or loosening of screws of a turbomachine assembly, the applicant proposes a screw fixing device equipped with a screw retaining means which is easy to install and which prevents any screw or part of a screw that is broken or unscrewed from becoming a projectile within the turbomachine assembly.

• à une première extrémité latérale, une première épingle qui ceint latéralement la tête de la première vis latérale,
• à une deuxième extrémité latérales, une deuxième épingle qui ceint latéralement la tête de la deuxième vis latérale, et
• entre les deux extrémités latérales, un palier central qui ceint transversalement la tête de la vis à risque.

According to a first aspect, the invention relates to a turbomachine assembly extending around an axis, comprising a first and a second part fixed by a fixing device, the fixing device comprising a screw at risk housed in the first and the second parts, and a first lateral screw and a second lateral screw arranged circumferentially on either side of the screw at risk, the screw at risk and the lateral screws each comprising a threaded rod housed in an orifice passing through the first and the second parts and a screw head mounted at one end of each threaded rod, said fixing device comprising a first retaining means extending laterally between the first side screw and the second side screw, the first retaining means comprising:

• at a first lateral end, a first pin which laterally surrounds the head of the first lateral screw,
• at a second lateral end, a second pin which laterally surrounds the head of the second lateral screw, and
• between the two lateral ends, a central bearing which transversely surrounds the head of the screw at risk.

The retaining means of this turbomachine assembly make it possible to maintain the screws of the fastening system bearing against the parts of the machine in which they are housed in order to prevent them from becoming flying debris when they are broken or loose.

• à une première extrémité latérale, une première épingle qui ceint latéralement l’écrou de la première vis latérale,
• à une deuxième extrémité latérale, une deuxième épingle qui ceint latéralement l’écrou de la deuxième vis latérale, et
• entre les deux extrémités latérales, un palier central qui ceint transversalement l’écrou de la vis à risque.

Advantageously, the screw at risk and the lateral screws are each provided with a nut, each screw cooperating in bringing together its respective nut so as to hold the first part against the second part, and the fixing device comprises a second retaining means extending laterally between the nut of the first lateral screw and the nut of the second lateral screw, the second retaining means comprising:

• at a first lateral end, a first pin which laterally surrounds the nut of the first lateral screw,
• at a second lateral end, a second pin which laterally surrounds the nut of the second lateral screw, and
• between the two lateral ends, a central bearing which transversely surrounds the nut of the screw at risk.

• la première épingle comporte une section en forme de C et la deuxième épingle comporte une section en forme de C inversé, l’ouverture de la première épingle en forme de C et l’ouverture de la deuxième épingle en forme de C inversé étant en regard l’une de l’autre.
• le palier central comporte un évidement en forme de U dont l’ouverture est orientée suivant une direction transversale aux ouvertures des épingles.
• il comporte une pluralité de premiers et/ou deuxièmes moyens de retenue agencés les uns à suite des autres circonférentiellement autour de l’axe de sorte à former un anneau de rétention des vis et/ou un anneau de rétention des écrous.
• la première épingle, la deuxième épingle et le palier central du premier moyen de retenue sont emboités dans une gorge aménagée dans la tête de chacune des vis à risque et vis latérales.
• la première épingle, la deuxième épingle et le palier central du deuxième moyen de retenue sont emboités dans une gorge aménagée dans l’écrou de chacune des vis à risque et vis latérales.
• le premier moyen de retenue comporte un palier intermédiaire apte à ceindre une tête d’une vis latérale intermédiaire, logée entre une des vis latérales et la vis à risque et/ou le deuxième moyen de retenue comporte un palier intermédiaire apte à ceindre un écrou d’une vis latérale intermédiaire, logée entre une des vis latérales et la vis à risque.
• les vis s’étendent principalement radialement ou axialement.

In addition to the characteristics which have just been mentioned in the previous paragraph, the turbomachine assembly according to one aspect of the invention may have one or more additional characteristics from among the following, considered individually or according to all technically possible combinations:

• the first hairpin has a C-shaped section and the second hairpin has an inverted C-shaped section, the opening of the first C-shaped hairpin and the opening of the second inverted C-shaped hairpin facing each other one from the other.
• the central bearing has a U-shaped recess whose opening is oriented in a direction transverse to the openings of the pins.
• it comprises a plurality of first and/or second retaining means arranged one after the other circumferentially around the axis so as to form a screw retention ring and/or a nut retention ring.
• the first hairpin, the second hairpin and the central bearing of the first retaining means are fitted into a groove provided in the head of each of the risk screws and lateral screws.
• the first hairpin, the second hairpin and the central bearing of the second retaining means are fitted into a groove provided in the nut of each of the risk screws and side screws.
• the first retaining means comprises an intermediate bearing capable of surrounding a head of an intermediate lateral screw, housed between one of the lateral screws and the screw at risk and/or the second retaining means comprises an intermediate bearing capable of surrounding a nut of an intermediate lateral screw, housed between one of the lateral screws and the screw at risk.
• the screws extend mainly radially or axially.

A second aspect of the invention relates to a turbomachine turbine, characterized in that it comprises an assembly as defined above.

A third aspect of the invention relates to a turbomachine, such as a turbojet or a turboprop, comprising an assembly or a turbine as defined above.

BRIEF DESCRIPTION OF FIGURES

Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which:

Figure 1, already described, shows a schematic sectional view of an example of an axial screw housed within a rotating machine to hold parts of said machine together;

Figure 2, already described, shows a schematic sectional view of an example of a radial screw housed within a rotating machine to hold parts of said machine together;

Figure 3 shows several schematic views of the retaining means according to the invention when said means is mounted around axial screws;

Figure 4 shows several schematic views of the retaining means according to the invention when said means is mounted around radial screws; And

FIG. 5 shows views of the retaining means according to the invention when said means is mounted both around axial screws and around screw tightening nuts.

DETAILED DESCRIPTION

An exemplary embodiment of a fastening device provided with screw retaining means is described in detail below, with reference to the accompanying drawings. This example illustrates the characteristics and advantages of the invention. It is however recalled that the invention is not limited to this example.

In the figures, identical elements are identified by identical references. For reasons of legibility of the figures, the size scales between the elements represented are not respected.

Examples of retaining means of a screw fastening system in a turbine are represented in FIGS. 3, 4 and 5. These retaining means are suitable for configurations where the fastening device 100 comprises a screw to be retained (for example a screw located at a location subject to high thermodynamic stresses or strong vibrations) housed in parts of the turbine between two other screws housed on either side of said screw to be retained, preferably in the same parts. The following description will refer to "one piece" of the turbine, it being understood that it may be two, three or more pieces joined together and held together by means of screws.

As shown in Figures 3 and 4, the screw to be retained 20, 30, also called "screw at risk", is housed in a part 16, 18 of the turbine, between a first side screw 21, 31 and a second side screw 22, 32. The screw at risk like the side screws are screws which conventionally comprise a threaded rod inserted into an orifice of the part 16, 18 and a head 23 mounted at the end of the threaded rod and projecting from said part 16, 18. The end of the threaded rod opposite the screw head 23 may be housed in a clamping nut, as described later.

The fixing device 100 comprises at least one first retaining means 110 extending laterally between the first lateral screw 21, 31 and the second lateral screw 22, 32. This first retaining means 110 can be of variable section, for example round , square, oval, rectangular, polygonal, etc., adapted to the dimensions of the screw head 23. The first retaining means 110, made of a non-deformable rigid material such as aluminum or any other rigid metal adapted to aeronautical constraints, extends between the first lateral screw 21, 31 and the second lateral screw 22, 32 and comprises, at one of its lateral ends, a first pin 112 capable of laterally surrounding the head of the first lateral screw 21, 31 and, at the other of its lateral ends, a second pin 113 capable of laterally surrounding the head of the second lateral screw 22, 32. The retaining means 110 further comprises, between its two ends, a central bearing 114 capable of transversely surrounding the head of the screw at risk 20, 30. The screw at risk 20, 30 and the side screws 21, 31 and 22, 32 are therefore linked to each other by the retaining means 110 via the pins 112, 113 and the center bearing 114.

The first pin 112 of the retaining means 110 has a C-shaped section. In other words, the pin 112 is formed by one end of the rod or rod 111 folded around the head of the first lateral screw 21, 31 to form an acute angle around the screw head 21, 31, an angle whose opening 112a is directed towards the risky screw 20. The pin 112 thus comprises two substantially straight and parallel portions 117 and a rounded portion 116 connecting the two straight portions.

The second pin 113 of the retaining means 110 has an inverted C-shaped section. In other words, the pin 113 is formed by one end of the rod or strip 111 folded around the head of the second lateral screw 22, 32 so as to form an acute angle around the screw head 22, 32, an angle whose the opening 113a is directed towards the risky screw 20. The first and second pins 112 and 113 of the retaining means 110 therefore comprise openings, respectively 112a and 113a, opposite one another. The hairpin 113 thus comprises two substantially rectilinear and parallel portions 117 and a rounded portion 116 connecting the two rectilinear portions.

The central bearing 114 of the retaining means 110 comprises a plate or a flat part positioned between the pins 112 and 113, for example halfway between said pins, and formed in one piece with the rod or the strip 111 of the retaining means. retainer 110 or attached to said rod or rod by any fastening means known in aeronautics, such as for example by welding or brazing. The central bearing 114 comprises a U-shaped recess 114a whose opening is oriented in a direction transverse to the openings 112a, 113a of the pins 112, 113. Thus, the central bearing 114 which partially surrounds the head of the screw at risk 20 , 30 has an opening oriented in a direction perpendicular to the openings 112a, 113a of the pins 112, 113 and directed towards the outside of the rotating machine, that is to say in the direction opposite to the axis of rotation AA.

Views A, B, C, D and E of Figure 3 show different perspectives of the fastener 100 when fitted to so-called "axial" screws. In these examples, the screw at risk 20 and the lateral screws 21 and 22 are housed axially in the part 16, that is to say they are arranged parallel to the axis of rotation AA of the rotating machine and are subjected to the centrifugal effect. The retaining means 110 connecting the risky screw 20 to the lateral screws 21, 22 is therefore positioned parallel to a radial face of the part 16, that is to say along a face of the part 16 oriented in a direction perpendicular to the axis of rotation of the rotating machine. In these examples, the rod or rod 111 extends parallel to the radial face of the part 16 between the first lateral screw 21 and the second lateral screw 22, the pins 112, 113 extend parallel to this same radial face bypassing the side screws 21, 22 and the central bearing 114 extends radially as far as the risky screw 20 so that the head of the risky screw 20 is housed in the recess 114a of said central bearing.

According to certain embodiments of the examples of FIG. 3, the pins 112, 113 surround the side screws 21, 22 leaving a clearance 115 between the head of said screws and the rounded portion 116 of the pins in order to provide a range of adjustment for mounting of the retaining means. The central bearing 114, on the other hand, has a recess 114a of dimensions adapted to the head of the screw at risk 20 so that said screw head is surrounded by said central bearing.

In some embodiments, and as shown in the views of Figure 3, the head of the screw at risk 20 is provided, over part or all of its contour, with a groove 118 adapted to receive the rod or strip 111. The groove 118 has a shape and dimensions adapted to the section and to the dimensions of the contour of the recess 114a of the central bearing 114 so as to ensure better retention, in particular axial and centrifugal, of the screw head. Similarly, the heads of the lateral screws 21, 22 can each comprise a groove 118, identical to the groove of the screw at risk 20 in order to ensure better interlocking of the screw head by the pins 112, 113 and thus ensure a improved axial, radial and centrifugal holding of the lateral screw heads.

Views A, B, C, D and E of FIG. 4 represent different perspectives of the fixing device 100 when it is adapted to so-called “radial” screws. In these examples, the screw at risk 30 and the lateral screws 31 and 32 are housed radially in the part 18, that is to say they are arranged in a direction perpendicular to the axis of rotation AA of the machine. rotating and are highly sensitive to vibrations. The retaining means 110 connecting the risky screw 30 to the lateral screws 31, 32 is therefore positioned parallel to an axial face of the part 18, that is to say along a face of the part 18 oriented in a direction parallel to the axis of rotation of the rotating machine. In these examples, the rod or strip 111 extends parallel to the axial face of the part 18 between the first lateral screw 31 and the second lateral screw 32, the pins 112, 113 extend parallel to this same axial face, bypassing the side screws 31, 32 and the central bearing 114 extends axially as far as the risky screw 30 so that the head of the risky screw 30 is housed in the recess 114a of said central bearing.

According to certain embodiments of the examples of FIG. 4, the pins 112, 113 surround the side screws 31, 32 leaving a clearance 115 between the head of said screws and the rounded portion 116 of the pins in order to provide a range of adjustment for mounting of the retaining means. The central bearing 114, on the other hand, has a recess 114a of dimensions adapted to the head of the risky screw 30 so that said screw head is surrounded by said central bearing.

In some embodiments, and as shown in the views of Figure 4, the head of the screw at risk 30 is provided, over part or all of its contour, with a groove 118 adapted to receive the rod or strip 111. The groove 118 has a shape and dimensions adapted to the section and to the dimensions of the contour of the recess 114a of the central bearing 114 so as to ensure better retention, in particular radial, of the screw head. Similarly, the heads of the lateral screws 31, 32 can each comprise a groove 118, identical to the groove of the screw at risk 30 in order to ensure better interlocking of the screw head by the pins 112, 113 and thus ensure a improved retention, particularly in rotation, of the lateral screw heads.

In the examples of Figures 3 and 4, the rod or rod 111 comprises several non-aligned linear segments giving the rod or rod 111 a non-rectilinear shape at several levels. Those skilled in the art will understand that all shapes of rod or rod 111 can be envisaged, for example a rounded or sawtooth shape since this shape makes it possible to connect the first and second pins 112, 113 as well as the central bearing 114 tightening both the side screws and the risk screw 20.

Whatever the embodiment, the fixing device 100 which has just been described makes it possible to maintain the screw at risk 20, 30, and in particular the head of the screw at risk, in the central bearing 114, itself maintained by the side screws. The screw head of the screw at risk 20, 30 is therefore to be held against the part 16, 18 by the retaining means whatever the state of the screw at risk. In other words, if the screw at risk 20, 30, subjected to strong external stresses, breaks or loosens, there is no risk of it becoming flying debris because it is held in place, pressed against the part 16, 18 of the impeller.

In the preceding description, the screw considered as the screw at risk is the central screw, positioned between the two lateral screws in the part of the rotating machine. It will be understood, of course, that all the screws attached to each other by the retaining means (in particular the side screws) are secured because of their connection with the other screws (central and/or side) of the turbine. The retaining means therefore makes it possible to retain both the screw at risk and the side screws, preventing each of these screws from becoming flying debris in the event of breakage or loosening.

It will further be understood that although the fastener 100 has been described for holding three screws together, the holding of more than three screws can be achieved with a retaining means in which a plurality of central bearings 114 would be arranged along the rod or rod 111, between the pins 112 and 113. In this case, the retaining means 110 comprises at least one intermediate bearing adapted to surround the head of an intermediate lateral screw, housed between one of the screws laterals and the screw at risk

More than three screws distributed over the part of the turbine can also be held together by positioning several retaining means 110 one after the other circumferentially around the axis AA, over the entire length or circumference of the part of the turbine . In this case, as shown in view D of FIG. 3, the fixing device 100 comprises several retaining means 110 mounted on the same face of the part of the turbine, each retaining means 110 connecting the same number of screws or , on the contrary, a different number of screws, depending for example on the stresses supported by each portion of said part. The retaining means 110 then constitutes a sort of retention ring for the screws.

In certain embodiments, the fixing device 100 comprises a second retaining means 210 arranged substantially parallel to the first retaining means 110, on the other face of the turbine part, and adapted to retain the nuts. Indeed, as shown in views A and B of Figure 5, the risky screws 20 and the side screws 21, 22 of certain turbines are inserted into a nut 25 positioned at the outlet of the orifice in which the rod is housed. threaded 24 of the screw. A nut 25 is then tightened around the threaded rod 24 of each screw. This nut 25 projects from the face of the part 16 opposite the face containing the screw heads 23.

In these embodiments, the second retaining means is substantially identical to the first retaining means 110. It may however have different dimensions (for example at the openings of the pins and the central bearing) from those of the first retaining means and adapted to the dimensions of the nuts 25 and in particular of the groove 119 provided in each of the nuts 25 to receive the second retaining means 210. As with the first retaining means 110, the second retaining means 210 can be adapted to hold three or more nuts together. It can also be associated with other second retaining means 210 to form a retaining ring for the nuts.

Even if the second retaining means 210 has been described and represented in FIG. 5 in the case where it holds axial screws, it will be understood that one or more second retaining means 210 can also be installed on a part 18 through which radial screws 30-32.

Although described through a certain number of examples, variants and embodiments, the fixing device according to the invention comprises various variants, modifications and improvements which will appear obvious to those skilled in the art, it being understood that these variants , modifications and improvements are within the scope of the invention.

Claims (11)

Turbomachine assembly extending around an axis (AA), comprising a first and a second part fixed by a fixing device, the fixing device comprising a screw at risk (20, 30) housed in the first and the second parts, and a first side screw (21, 31) and a second side screw (22, 32) arranged circumferentially on either side of the risky screw (20, 30), the risky screw and the side screws comprising each a threaded rod (24) housed in an orifice passing through the first and the second parts and a screw head (23) mounted at one end of each threaded rod, said fixing device comprising a first retaining means (110) extending laterally between the first side screw and the second side screw, the first retaining means comprising:

• at a first lateral end, a first pin (112) which laterally surrounds the head of the first lateral screw (21, 31),
• at a second lateral end, a second pin (113) which laterally surrounds the head of the second lateral screw (22, 32), and
• between the two lateral ends, a central bearing (114) which transversely surrounds the head of the screw at risk (20, 30).

Turbomachine assembly according to Claim 1, in which the screw at risk (20, 30) and the lateral screws (21, 31) are each provided with a nut, each screw cooperating in close proximity with its respective nut so as to maintain the first part against the second part, and wherein the fastening device comprises a second retaining means (210) extending laterally between the first side screw nut (21, 31) and the second side screw nut (22, 32), the second retaining means comprising:

• at a first lateral end, a first pin (112) which laterally surrounds the nut of the first lateral screw (21, 31),
• at a second lateral end, a second pin (113) which laterally surrounds the nut of the second lateral screw (22, 32), and
• between the two lateral ends, a central bearing (114) which transversely surrounds the nut of the screw at risk (20, 30).

Turbomachine assembly according to Claim 1 or 2, characterized in that the first hairpin (112) has a C-shaped section and the second hairpin (113) has an inverted C-shaped section, the opening of the first hairpin in the shape of a C and the opening of the second hairpin in the shape of an inverted C facing each other. Turbomachine assembly according to Claim 3, characterized in that the central bearing (114) comprises a U-shaped recess, the opening of which is oriented in a direction transverse to the openings of the pins. Turbomachine assembly according to any one of Claims 1 to 4, characterized in that it comprises a plurality of first and/or second retaining means (110, 210) arranged one after the other circumferentially around the axis (AA) so as to form a screw retention ring and/or a nut retention ring. Turbomachine assembly according to any one of Claims 1 to 5, characterized in that the first hairpin (112), the second hairpin (113) and the central bearing (114) of the first retaining means (110) are fitted into a groove (118) arranged in the head of each of the screws at risk and side screws. Turbomachine assembly according to any one of Claims 1 to 6, characterized in that the first hairpin (112), the second hairpin (113) and the central bearing (114) of the second retaining means (210) are fitted into a groove (119) arranged in the nut of each of the screws at risk and side screws. Turbomachine assembly according to one of Claims 1 to 7, characterized in that the first retaining means (110) comprises an intermediate bearing capable of surrounding a head of an intermediate lateral screw, housed between one of the lateral screws and the screw at risk and/or the second retaining means (210) comprises an intermediate bearing capable of encircling a nut with an intermediate lateral screw, housed between one of the lateral screws and the screw at risk. A turbomachine assembly according to any of claims 1 to 8, wherein the screws (20, 21, 22) extend primarily radially or axially. Turbomachine turbine, characterized in that it comprises an assembly according to any one of Claims 1 to 9. Turbomachine, such as a turbojet or a turboprop, characterized in that it comprises an assembly according to any one of Claims 1 to 9 or a turbine according to Claim 10.