EP1950392B1 - Device for assembling two units, for example for a turbomachine stator - Google Patents

Description

TECHNICAL AREA

The present invention relates generally to a device for assembling two assemblies, of the type comprising a yoke intended to be attached to a first assembly and a connecting member intended to be attached to a second assembly.

The invention applies in particular but not exclusively to the field of turbomachines, preferably taking the form of an aircraft turbojet engine, for example to ensure the connection between two annular and concentric sets of a turbine or compressor stator.

STATE OF THE PRIOR ART

From the prior art, several assembly devices of the type mentioned above are known.

First, we know a conventional device said clevis with two ears, within which it seeks to perform a tightening of the connecting member between the two ears, using a screw / nut assembly passing through the device. In such a case, the efforts essentially pass by friction of the two opposite faces of the connecting member against respectively the inner faces of the two ears pinching the same member.

The disadvantage of this type of assembly lies in the fact that it is possible with a very small clearance between the different parts, before tightening the screw / nut assembly. Indeed, too large initial spacing between the ears of the clevis create during clamping a pinch and a stress of these ears, and therefore a weakening thereof.

On the other hand, with this assembly, it is only possible to bring the connecting member parallel to the ears of the yoke during its introduction between them, namely perpendicular to the axes of the clevis orifices, applying a movement translation parallel to a said direction of clevis orientation. This inevitably makes assembly difficult for an operator, even impossible in certain circumstances as described in the example below, and necessarily implies that the parts are positioned very precisely relative to each other to achieve the aforementioned introduction.

Indeed, it is possible to provide a case where the first annular assembly is disposed radially inwardly with respect to the second annular assembly, with the yoke of each of the assembly devices equipping this first annular assembly being arranged in such a way as to present, in top view by relative to this yoke, an inclined yoke orientation of the same wedge angle with respect to an axis of the first and second annular assemblies. In this configuration, it appears clearly impossible to obtain the simultaneous introduction of each of the connecting members, distributed circumferentially on the second set, in their associated yoke, and this regardless of the nature of the relative movement applied between the first and the second sets.

From the prior art, there is also known a conventional device also said clevis with two ears, but in which the connecting member is not clamped between the two ears but separated from them. In this case, the forces then pass through the shear and bending of the axis system passing through the various parts of the assembly device. Nevertheless, the major disadvantage of this type of assembly comes from the presence of the degree of freedom attached to the connecting member located at a distance from the two clevis ears, offering the possibility to the same member to move along the system of 'axis. Therefore, due to the lack of plating of this connecting member against the clevis ears, it is therefore impossible to ensure accurate positioning of the second set relative to the first set.

In addition, if a clearance is provided between the axis system and the passage opening made on the connecting member, in particular for the purpose of tolerating a positioning uncertainty before the introduction of the axis system through this orifice, the mechanical connection obtained then becomes extremely sensitive to vibrations.

Finally, there is also known from the prior art another conventional device, said clevis to single ear, wherein the connecting member is tight on the single ear of the yoke. This configuration of course has the advantage of generating almost no space constraint for the operator bringing the organ to the single ear. In other words, unlike the previous embodiments, the establishment of the member on the yoke can be performed in a manner other than by applying a translation movement parallel to the clevis orientation, this which offers freedom of action extended to the operator.

However, the ear and the organ undergo a significant bending because of the dissymmetry of the fixation, which creates a strong moment. In addition, in order to pass forces of the same intensity level, this type of fastening requires oversized parts compared to those constituting the two-ear clevis devices discussed above, and consequently generates congestion.

An assembly of the type mentioned below is known from the document US 4684280 .

STATEMENT OF THE INVENTION

The object of the invention is therefore to propose an assembly device at least partially overcoming the disadvantages mentioned above, relating to the embodiments of the prior art.

To do this, the invention firstly relates to a turbomachine assembly according to claim 1.

The invention has the particularity of benefiting from all the advantages relating to the embodiments of the prior art, without presenting the disadvantages thereof.

Indeed, it is first specified that the assembly device has a design allowing it to be constituted by elements of small dimensioning, in that the presence of a clevis with two ears avoids the harmful effects of bending encountered in single ear solutions of the prior art.

In addition, it is advantageously possible to obtain a precise final positioning of the connection member relative to the yoke, since this member is fixedly held in contact against one of the two ears thereof. Therefore, this also makes it possible to obtain a very precise relative positioning between the first and second assemblies bearing this assembly device according to the invention.

In addition, even if a clearance is preferably provided between the axis system and the passage opening made on the connecting member, in particular for the purpose of tolerating a positioning uncertainty before the introduction of the axis system to Through this orifice, the mechanical connection is advantageously insensitive to vibrations, insofar as the connecting member is fixedly fixed by friction between the shoulder of the axis system and one of the two ears.

It is therefore to be understood that the spacing between the two lugs is much greater than the thickness of the connecting member, since it is located at a distance from the first lug ear in the assembled position. Thus, this specificity offers the advantage of offering the operator great freedom in the manner of operating the introduction of the body into the yoke, which is then of course no longer limited to the application a translational movement parallel to the clevis orientation, as was the case previously.

The invention applies to a case where the first annular assembly is disposed radially inwardly with respect to the second annular assembly on which it is fixedly mounted by means of several circumferentially distributed assembly devices, with the yoke of each these devices equipping the first annular assembly arranged to have, in top view with respect to this yoke, an inclined yoke orientation of the same angle of registration with respect to an axis of the first and second annular assemblies. In this configuration, for example encountered on a turbomachine stator, the simultaneous introduction of each of the connecting members in their associated yoke becomes possible by applying a simple relative movement of helical type between the first and second sets, according to the invention. axis of these.

By way of example, the thickness (e) of the connecting member in one direction of the shear axis system fulfills the condition 1.3 <E / e <2.5, with (E) corresponding to a spacing between the first and second clevis ears in the same direction. Naturally, this ratio can be modified by those skilled in the art, according to the needs met. In particular, in the preferential case indicated above where it is sought to perform a simultaneous introduction of each of the connecting members in their associated yoke by applying a helical relative movement between the first and second sets, according to the axis of the latter, the E / e ratio allowing such a mounting by "screwing" can then be set according to various parameters such as the value of the wedging angle, the height and thickness of the ears, the radius the first set wearing the screeds, etc.

In other words, it is stated that the invention can be applied as soon as the movement of mounting imposes a higher clearance, even very slightly, the only set of manufacturing tolerances. For example, if the wedging angle is very small, of the order of 5 °, the E / e ratio may be less than 1.3, but the mounting movement must still be helical, ie of the type mentioned above.

According to a first preferred embodiment of the present invention, the axis system comprises a head and a bushing resting at one of its ends against the head, the bushing constituting the widened portion passing through the first clevis orifice, and forming the shoulder to the other of its ends. In such a case, it is therefore expected that the diameter of the screw head is less than or equal to the outer diameter of the sleeve, which in turn corresponds substantially to the diameter of the first clevis hole. However, in the case where the screw head is entirely offset externally with respect to the yoke, that is to say having no contact therewith, it could have a diameter greater than the outer diameter of the sleeve , therefore greater than the diameter of the first clevis hole, without departing from the scope of the invention.

According to a second preferred embodiment of the present invention, the axis system takes the form of a shaft made in one piece, comprising a head constituting the enlarged portion passing through the first clevis hole. In this second mode, it is therefore the screw head which passes right through the first clevis hole, and which forms the shoulder of tightening the connecting member at its end bearing the threaded portion.

In these two preferred embodiments, the shear axis system is preferably not in abutment with the first clevis lug, in order to be certain to obtain contact between the shoulder and the connecting member.

Preferably, in order to provide easy mounting, it is expected that the first clevis hole is larger than the second clevis hole.

Still preferentially, the assembly constitutes a stator portion of the turbomachine.

On the other hand, the invention also relates to a turbomachine module comprising at least one assembly as presented above.

Preferably, the module is a turbomachine turbine or compressor, high pressure or low pressure.

Finally, another object of the invention is a turbomachine such as an aircraft turbojet, comprising at least one module as described above.

Other advantages and features of the invention will become apparent in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 représente une vue partielle en coupe d'une turbomachine selon un mode de réalisation préféré de la présente invention ;
• la figure 2 montre une vue partielle de face d'un assemblage de stator appartenant à la turbomachine montrée sur la figure 1, cet assemblage constituant une partie de stator ;
• la figure 2a représente une vue schématique partielle de dessus du premier ensemble annulaire appartenant à l'assemblage de stator montré sur la figure 2 ;
• la figure 3 montre une vue en coupe selon la ligne III-III de la figure 2, sur laquelle il est représenté un dispositif d'assemblage selon un premier mode de réalisation préféré de la présente invention ; et
• la figure 4 montre une vue similaire à celle de la figure 3, sur laquelle le dispositif d'assemblage se présente sous la forme d'un second mode de réalisation préféré de la présente invention.

This description will be made with reference to the appended drawings among which;

• the figure 1 is a partial sectional view of a turbomachine according to a preferred embodiment of the present invention;
• the figure 2 shows a partial front view of a stator assembly belonging to the turbomachine shown on the figure 1 this assembly constituting a part of a stator;
• the figure 2a represents a partial schematic view from above of the first annular assembly belonging to the stator assembly shown in FIG. figure 2 ;
• the figure 3 shows a sectional view along line III-III of the figure 2 , on which there is shown an assembly device according to a first preferred embodiment of the present invention; and
• the figure 4 shows a view similar to that of the figure 3 , on which the assembly device is in the form of a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the figure 1 , we see a part of a turbomachine 1 according to a preferred embodiment of the present invention, and more particularly a turbomachine module 2, which is here a high-pressure turbine called HP turbine of the turbomachine, taking as its shape of a turbojet engine for aircraft.

The module 2 comprises a stator partially composed by an assembly 4 also object of the present invention, this assembly 4 generally comprising a first set 6 and a second set 8 annular and concentric along a turbomachine axis (not shown), also corresponding to the axis of these sets 6, 8. As will be detailed below, the sets 6, 8 are fixedly connected to one another by a plurality of circumferentially spaced circumferentially spaced connection devices 10, also referred to as "cyclic".

As visible on the figure 1 , the first and second sets 6, 8 define between them an annular space 12 forming a transverse section of the primary channel of the gas 14 of the turbomachine. In other words, the gases escaping from the combustion chamber (not shown) of the turbomachine take the annular primary gas channel 14 partially defined between the annular assemblies 6 and 8, which causes them to cross the space annular 12 of the stator assembly 4 while traveling downstream of the turbomachine. The annular space 12 forming a transverse section of the primary channel of the gases 14 may not be directly delimited radially by the two assemblies 6, 8, but by internal and external annular covers 16, 18 fixed respectively on these same assemblies, between these last.

More specifically with reference to the figure 2 a part of the stator assembly 4 can be seen showing the plurality of circumferentially spaced apart assembly devices 10 others around the axis 20 of the turbomachine and sets 6, 8.

It is noted that one of the peculiarities of the assembly devices 10 which will be detailed later is to provide for each of them a yoke 22 having a non-zero wedging angle with respect to the axis 20, this angle of wedging being identical for each of the clevises 22 made. In other words and with reference to the figure 2a , in plan view with respect to any screed 22, the clevis orientation 24 is inclined by a setting angle A with respect to the axis 20, the value of which may be between 0 and 90 °. As an indication, this clevis orientation 24 corresponds to an axis parallel to each of the two clevis ears 26a, 26b, and therefore extends along the inter-ear space. As mentioned above, the diagram shown on the figure 2a is valid for all the clevises 22 fixedly attached to the first assembly 6, with which they may optionally be made in one piece. Thus, the wedging angle A is of the same size and in the same direction for each of the clevises 22, which may also have an inclination in a radial direction, as is clearly visible on the figures 2 and 2a .

As will be detailed later, the yoke 22 of an assembly device 10 is provided to receive between its two ears the radially inner end of a connecting member 28 in the form of an arm passing through the annular space 12 , this member 28 having an outer radial end reported fixed on the second assembly 8, for example by means of screwed fittings.

One of the peculiarities of the present invention is to offer a design allowing simultaneous introduction of each of the connecting members 28 in their associated clevis 22, by facing the first and second sets followed by the application of a simple movement Relative helical type or screwing along the axis 10. To do this, it is in particular provided a large spacing between the ears 26a, 26b of the yoke, as will now be described with reference to the figure 3 .

In this figure showing a device 10 in its assembled position, it can be seen that the connecting member pierced with a passage opening 30 at the inner radial end is housed between a first clevis lug 26a and a second clevis lug 26b, respectively having a first clevis hole 32a and a second clevis hole 32b.

In addition, the device 10 comprises a shear axis system 34 successively passing through the first clevis hole 32a, the through hole 30 and the second clevis hole 32b. Overall, this system 34 comprises a screw 36 having a head 38 preferably provided with a torque recovery system providing an anti-rotation function for tightening the associated nut system, and a threaded barrel 40 to its free end. The system 34 also comprises a clamping sleeve 42 fitted into the barrel 40 and resting against the head Finally, the device also comprises a nut system 44 that can take the form of a simple nut, screwed onto the threaded end 46 of the screw barrel and resting against the outer face of the second clevis lug. 26b.

In this configuration, opposite the threaded end 46, the clamping sleeve 42 of the axle system 36 constitutes an enlarged portion passing right through the first clevis hole 32a, implying in particular that the screw head 38 is located outside and at a distance from the clevis 22 against which it does not come into abutment. In this respect, it is preferably provided that the diameter of the screw head 38 is less than or equal to the outer diameter of the sleeve, which in turn corresponds substantially to the diameter of the first clevis hole 32a.

Thus, the sleeve 42 forming an enlarged portion thus extends to the inside of the inter-ear space 48, to constitute at its end located in this space 48 a shoulder 50 which is also located between the first and second clevis ears 26a, 26b.

This shoulder 50 abuts against one of the faces of the connecting member 28, the other of its faces opposite the first being in abutment against an inner face of the second lug 26b.

Consequently, the connecting member 28 is fixedly held by pinching / rubbing away from the first ear 26a, thanks to the plating carried out by the shoulder 50.

As an indication, it is preferentially provided a substantially identical diameter for the screw shaft 40, the second clevis hole 32b, and the inner surface of the clamping sleeve 42, the diameter of the through hole 30 being able to meanwhile be slightly greater in order to tolerate a positioning uncertainty before the introduction of the spindle system 36 through the orifice 30. Nevertheless, it is noted that the spindle system 36 is preferably provided to operate essentially in shear in cooperation with the passage opening 30, and secondarily in friction by the contact between the opposite faces of the member 28 and the inner face of the lug 26b and the shoulder 50, respectively.

In the case shown on the figure 3 , the screw shaft 40 having a constant diameter between its free end and that fixedly attached to the screw head 38, it is clear that the diameter of the second clevis hole 32b is smaller than that of the first clevis hole 32a , through which the axle system 36 can slide freely during assembly, along the axis 52 of the clevis apertures 32a, 32b.

Naturally, to allow the assembly by simple relative helical movement between the first set 6 and the second set 8 along the axis 20, the skilled person can adapt the ratio E / e between the gap E between the first and second clevis ears 26a, 26b in a direction of the shear axis system 36 coincides with the axis 52 of the clevis orifices, and the thickness e of the member connecting connection 28 in the same direction 52. As an indicative example, this ratio may be such that it fulfills the condition 1.3 <E / e <2.5.

Referring now to the figure 4 an assembly device according to a second preferred embodiment of the present invention can be seen. It has strong similarities with the first mode described above, and, in this respect, it is specified that the elements bearing the same reference numerals in the figures correspond to identical or similar elements.

Thus, it can be seen that the only difference lies in the fact of providing an axle system 36 in one piece, the head 38 carrying the screw shaft 40 is merged with the enlarged portion 42 forming a shoulder 50 and passing through the first clevis hole 32a. Again, in the assembled state as shown, there is no abutment between the first lug 26a and the screw head 38 therethrough.

Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples. In this regard, it would be possible to consider placing the yokes on the second set and the connecting members on the first set, without departing from the scope of the invention.

Claims (9)

1. An assembly (4) for turbomachine comprising first and second annular and concentric assemblies (6, 8) fixedly joined to one another via a plurality of joining devices (10) spaced circumferentially apart, said first and second assemblies (6, 8) defining an annular space (12) between them forming a transverse portion (14) of the primary duct for the gases of said turbomachine,
   in that each joining device (10) comprises a clevis (22) added onto said first assembly (6) and an arm-shaped connecting member (28) passing though said annular space (12) and added onto the second assembly (8), said connecting member (28) pierced with a through hole (30) being housed between a first and a second lug (26a, 26b) of said clevis respectively having a first clevis hole (32a) and a second clevis hole (32b), said device further comprising a shear pin system (36) passing through each of said first clevis hole (32a), second clevis hole (32b) and through hole (30) and comprising a threaded end (46) cooperating with a nut system (44) bearing against said second clevis lug (26b), said pin system (36) opposite the threaded end (46) comprising a widened portion (42) passing through said first clevis hole (32a) and forming a shoulder (50) located between said first and second clevis lugs (26a, 26b), said connecting member (28) being positioned away from said first clevis lug (26a) and lying flat on one side against said shoulder (50) and on the other side against said second clevis lug (26b) respectively,
   and in that the clevis (22) of each of the joining devices (10) equipping said first annular assembly (6) is arranged so that, as seen from overhead this clevis (22), it has a clevis orientation (24) set at the same pitch angle (A) relative to an axis (20) of said first and second annular assemblies (6, 8).
2. The assembly according to claim 1, characterized in that the thickness (e) of said connecting member (28) along a direction of the shear pin system (52) meets the condition 1.3 < E/e < 2.5 where (E) corresponds to a distance between said first and second clevis lugs (26a, 26b) along the same direction (52).
3. The assembly according to claim 1 or claim 2, characterized in that said pin system (36) comprises a head (38) and a bushing (42) bearing at one of its ends against said head (38), the bushing (42) forming said widened portion passing through said first clevis hole (32a) and forming said shoulder (50) at the other of its ends.
4. The assembly according to claim 1 or claim 2, characterized in that said pin system (36) is in the form of a pin made in a single piece comprising a head (38) forming said widened portion (42) passing through said first clevis hole (32a).
5. The assembly according to any of the preceding claims, characterized in that said first clevis hole (32a) is larger than said second clevis hole (32b).
6. The assembly according to any of the preceding claims, characterized in that it forms a stator portion of said turbomachine.
7. A turbomachine module (2) characterized in that it comprises at least one assembly (4) according to any of the preceding claims.
8. The turbomachine module (2) according to claim 7, characterized in that it is a turbine or compressor of a turbomachine.
9. A turbomachine (1) comprising at least one module (2) according to claim 7 or claim 8.

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