FR3039211B1 - COMPRESSION DEVICE FOR IMPROVING THE SEAL BETWEEN A TURBOMACHINE COVER AND A BEARING SUPPORT PART - Google Patents

Abstract

The invention relates to a compression device (40) for a seal (31) held between a first flange (19) and a second flange (20), a first fixing screw (15-1) and a second fixing screw (15-2) contributing to the fixing of the first flange (19) and the second flange (20), the compression device (40) comprising: A first end portion (51-1) comprising a first fastening element ( 52-1) to the first fixing screw (15-1) A second end portion (51-2) having a second securing element (52-2) to the second fixing screw (15-2) An intermediate part located between the first end portion (51-1) and the second end portion (51-2), including bearing means on the first flange (19) so as to exert pressure on the joint (31).

Description

COMPRESSION DEVICE FOR IMPROVING THE SEAL BETWEEN A COVER OF

TURBOMACHINE AND A PIECE OF BEARING SUPPORT

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the general field of turbomachines. It relates more particularly to a holding bar participating in the seal between a turbomachine cover and a bearing support member.

BACKGROUND OF THE INVENTION

A turbomachine conventionally comprises a gas turbine consisting of a plurality of stages of stationary blades constituting a stator, and a plurality of stages of blades constituting a rotor mounted on a turbine shaft. The turbine shaft is centered and guided in rotation by bearings. In order to limit their wear by friction, the bearings require a continuous supply of oil. They are thus placed in pressurized enclosures containing oiled air.

FIG. 1 represents a longitudinal section of a downstream end of such a turbomachine 10, with respect to the longitudinal axis X along which the turbomachine extends. It is noted that upstream and downstream are to be considered relative to the direction of air flow within the operating turbomachine. Said turbomachine 10 comprises a turbine shaft 11 and bearings, including a downstream bearing 12 visible in Figure 1. It is noted that the name "downstream bearing" refers to the bearing located further downstream of the turbomachine. The downstream bearing 12 is held by an annular support piece 13 fixed to the stator 14 of the turbomachine 10 by means of fixing screws 15-x. As previously mentioned, the downstream bearing 12 is housed in an enclosure 16 containing oiled air. The chamber 16 is underpressure with respect to a contiguous enclosure 37, the enclosure 16 and the enclosure 37 communicating via sealing systems 17. This makes it possible to confine the oiled air in the enclosure 16 between the sealing systems 17, because of the pressure difference. For this, pressurized air taken from a low-pressure compressor of the turbomachine 10 is injected into the contiguous enclosure 37.

An annular cover 18 is mounted on the support member 13. More specifically, the cover 18 has a radially extending, upstream end face 19 fixed on a downstream end face 20 of the support member 13. , also annular and extending radially. Figure 2 is a perspective view of the cover 18 mounted on the support member 13, seen from the downstream of the turbomachine 10, and Figure 3 is a sectional view. The upstream end face 19 of the cover 18 comprises a plurality of through openings 21-x intended to be placed opposite a plurality of through-22-x perforations (visible in FIG. 3) made on the end face. downstream 20 of the support member 13, for fixing the cover 18 on the support member 13 by means of the fixing screws 15-x.

The lid 18 also comprises a plurality of tubes 30-x intended for the circulation of air at atmospheric pressure, to put at atmospheric pressure chambers 38 surrounding the contiguous enclosure 37. As can be seen in FIG. 2, each tube 30 -x crosses the upstream end face 19 of the cover 18, surrounded by two openings 21-x. Between two adjacent tubes 30-x, at the upstream end face 19, there are two openings 21-x.

The lid 18 is sealingly mounted on the support piece 13 by means of an annular seal 31 compressed between the upstream end face 19 of the cover 18 and the downstream end face 20 of the support piece 13 Figure 4 shows a seal 31 conventionally used in such applications. The seal 31 has 32-x through holes intended to be centered on the openings 21-x of the upstream end face 19 of the cover 18 and the perforations 22-x of the downstream end face 20 of the part of 13. Thus, as shown in Figure 3, the holes 32 allow to pass the 15-x fixing screws used for fixing the upstream end face of the cover 18 on the downstream end face 20 of the 13. Each fastening screw 15-x is inserted from the downstream, and therefore crosses, from downstream to upstream: an opening 21-x of the upstream end face 19 of the cover 18, a 32-x breakthrough of the seal 31, and a 22-x perforation of the downstream end face 20 of the support piece 13.

Despite the presence of the seal 31 between the cover 18 and the support part 13, many cases of oil leakage are recorded. It turns out that the forces distributed on the seal 31 are not distributed uniformly. The pressures exerted in the areas between the 32-x holes of the seal 31 are indeed lower than the pressures exerted at the 32-x breakthroughs. The compression of the seal 31 is not optimal, and the sealing of the enclosure 16 is no longer guaranteed. The oil is likely to seep out of the basket, making inspections necessary under the wing, which prevents the aircraft from continuing its flights. Coke deposits on the components of the turbomachine near the leak are also observed, which requires extensive cleaning in the workshop.

GENERAL DESCRIPTION OF THE INVENTION The invention therefore aims to provide a solution for standardizing the compression of the joint. The invention therefore relates to a compression device for a seal sandwiched between a first flange and a second flange, a first fixing screw and a second fixing screw contributing to the fixing of the first flange and the second flange, the compression device comprising:

A first end portion comprising a first fastening element to the first fastening screw

A second end portion having a second securing element to the second fixing screw

An intermediate portion located between the first end portion and the second end portion, comprising bearing means on the first flange so as to exert pressure on the joint.

The first securing element secures the compression device to the first fixing screw, said first fixing screw being used for fixing the upstream end face of the cover (first flange) on the downstream end face of the the support piece (second flange). The second securing element makes it possible to secure the compression device to the second fixing screw, said second screw being used for fixing the upstream end face of the cover (first flange) on the downstream end face of the part. support (second flange). Thus, the first securing element and the second securing element being its extremal parts of the compression device, the holding bar is generally intended to be installed between the first fixing screw and the second fixing screw.

The support means, which belong to the intermediate part situated between the first extremal part and the second extremal part, thus make it possible to exert pressure on an area of the upstream end face of the cover located between the first fixing screw and the second fixing screw. This zone in turn presses on an area of the joint located between two holes for fixing screws of said seal. With an additional compression point on the seal being added, the compression of the seal is improved. Indeed, the additional stress on the seal makes it possible to tighten the seal in an area where it was the least compressed.

By securing such a compression device to each pair of neighboring fixing screws, many compression points can be added over the entire circumference of the seal.

The compression of the joint is standardized. In addition, it is noted that thanks to this system, neither the cover nor the support part are to be modified.

The compression device according to the invention may have one or more of the features below, considered individually or in any technically possible combination.

Advantageously, the first securing element is a first through hole adapted to receive the first fastening screw, and the second fastening element is a second through hole adapted to receive the second fastening screw.

The first fixing screw is then intended to be screwed into the first through hole of the first end portion before being screwed into an opening of the upstream end face of the cover, a seal breakthrough, and a perforation of the face downstream end of the support piece. Similarly, the second fixing screw is intended to be screwed into the second through hole of the second end portion before being screwed into another opening of the upstream end face of the cover, another breakthrough of the seal, and a other perforation of the downstream end face of the support piece. This allows a simple and stable connection of the compression device on the upstream end face of the cover.

In a first nonlimiting embodiment, the intermediate portion comprises an intermediate portion, and the support means comprise: a first threaded orifice passing through the intermediate portion a first adjusting screw adapted to be screwed into the first orifice so as to support on the first flange.

The first threaded through hole allows insertion of the first set screw. When this first adjustment screw is screwed with a suitable tightening torque, it presses on an area of the upstream end face of the cover located between the first fixing screw and the second fixing screw. This zone in turn presses on an area of the joint located between two holes for fixing screws of said seal. With an additional compression point on the seal being added, the compression of the seal is improved.

Advantageously, the first end portion and the second end portion are of greater thickness than the thickness of the intermediate portion.

Thus, the intermediate portion is raised when the compression device is secured to the fastening screws at the end portions. This allows in particular a visual verification of the screwing of the first adjustment screw against the upstream end face of the lid. This also makes it possible to leave a space between the intermediate portion and the upstream end face of the cover to possibly place an intermediate piece of protection of the upstream end face of the cover against the depression of the first adjustment screw.

Advantageously, the support means comprise a second threaded orifice passing through the intermediate portion and a second adjusting screw adapted to be screwed into the second orifice according to an adjustable torque.

The second through hole allows the insertion of a second adjusting screw. When this second adjusting screw is screwed, it presses on an area of the upstream end face of the cover located between the first fixing screw and the second fixing screw. This zone in turn presses on an area of the joint located between two holes for fixing screws of said seal. The first fastening screw and the second fastening screw add two additional compression points on the seal, which improves seal compression. Of course, other threaded through holes may be made in the intermediate portion to increase the number of compression points on the joint.

Advantageously, the support means comprising a first clamping nut adapted to prevent unscrewing of the first adjusting screw.

Without such a clamping nut, vibrations of the compression device could loosen the adjusting screw.

Advantageously, the support means comprise an insert adapted to be positioned between the adjusting screw and the first flange.

The intermediate piece avoids the marking of the first flange by the adjusting screw, when the adjusting screw is in abutment against the first flange.

In a second nonlimiting embodiment, the intermediate portion comprises an intermediate portion, and the support means comprise at least a first boss of the intermediate portion, the first boss being of suitable dimensions to press on the first flange.

The boss is for example a vertex of a corrugation of the intermediate portion, or a protrusion on the intermediate portion. The first boss creates a constraint on the first flange, between the first fixing screw and the second fixing screw, transmitting to the seal.

Advantageously, the support means comprise a second boss of the intermediate portion, the second boss being of suitable dimensions to press on the first flange. The number of bosses can be chosen depending on the location of the compression device: the more the first and second fixing screws are spaced, the more advantageous it is to add intermediate compression points to the joint.

Note that the second embodiment of the compression device has the advantage of having fewer parts, which reduces costs, and to be faster installation by an operator than the first embodiment. Indeed, in the second embodiment, there is no need for adjusting screw to be tightened to a suitable torque, or nut to lock them, etc.

Advantageously, the intermediate portion of the first or second embodiment comprises stiffening means.

These stiffening means are in the form of ribs or bosses, for example.

In one embodiment, the first flange belongs to a turbomachine cover, and the second flange belongs to a bearing support part of said turbomachine. The invention will be better understood in the light of the description which follows and with reference to the figures listed below.

BRIEF DESCRIPTION OF THE FIGURES

The figures are presented only as an indication and in no way limitative. The figures show: in FIG. 1, already described, a downstream end in longitudinal section of a turbomachine, said turbomachine comprising a bearing support part and a cover fixed on said part; in FIG. 2, already described, a perspective view from downstream of the turbomachine of the cover of FIG. 1, fixed on the support piece of FIG. 1; in Figure 3, already described, a sectional view of an assembly comprising the cover and the bearing support member of Figure 1, surrounding a seal; in FIG. 4, already described, a front view of the seal of FIG. 3, intended to be placed between the cover and the bearing support piece of FIG. 1; FIG. 5 is a perspective view from downstream of the lid of FIG. 1, fixed on the support member of FIG. 1, on which a compression device is mounted according to a first general embodiment of FIG. invention; in Figure 6, a sectional view of the compression device of Figure 5; in Figure 7, a sectional view of a compression device according to a variant of the first general embodiment of the invention; in Figure 8, a sectional view of a compression device according to a second general embodiment of the invention.

GENERAL DESCRIPTION OF THE INVENTION

Unless otherwise specified, the same element appearing in different figures has a unique reference.

Figures 5 and 6 illustrate a first general embodiment of a compression device 40 according to the invention, Figure 7 illustrates a variant of this first general embodiment, and finally Figure 8 illustrates a second general embodiment.

The compression device 40 is intended to improve the seal between a turbomachine cover 18 and a bearing support member 13. The cover 18 comprises an annular upstream end face 19, also called first flange 19, extending radially. relative to a longitudinal axis according to the extends the turbomachine. The first flange 19 has a plurality of through openings 21-x, usually a dozen, distributed over the first flange 19. A first opening 21-1 and a second opening 21-2 are shown in Figures 5 to 8.

The bearing support piece 13 comprises an annular downstream end face 20, also called second flange 20, also extending radially. The second flange 20 has a plurality of through perforations 22-x as much as 21-x openings distributed over the second flange 20. The perforations 22-x are positioned opposite the openings 21-x, for fixing the cover 18 on the support piece 13 by means of fixing screws 15-x. A first perforation 22-1 and a second perforation 22-2 respectively opposite the first opening 21-1 and the second opening 21-2 are shown in FIGS. 5 to 8.

A flat circular seal 31, visible in FIGS. 6 to 8, is compressed between the first flange 19 and the second flange 20. The seal 31 has a plurality of apertures 32-x as well as openings 21-x and 22-x perforations, distributed on the seal 31. The 32-x bores are positioned opposite the openings 21-x on one side and 22-x perforations on the other side, for a hermetic attachment of the cover 18 on the support piece 13 by means of the fixing screws 15-x. A first breakthrough 32-1 and a second breakthrough 32-2 respectively opposite the first opening 21-1 and the second opening 21-2 on the one hand, and the two perforations 22-1, 22-2 of on the other hand, are shown in Figures 5 to 8.

In the first general embodiment and the second general embodiment, the compression device 40 comprises a one-piece support bar 50 positioned on the first flange 19, and extending generally between a first fixing screw 15-1 and a second fixing screw 15-2 of the cover 18 on the support piece 13.

The holding bar 50 has a first end portion 51-1 having a first securing member 52-1 to the first fixing screw 15-1. In the general embodiments described, the first securing element 52-1 is in the form of a first through hole in which is inserted the first fixing screw 15-1. The first fixing screw 15-1 is then inserted into a first opening 21-1 of the first flange 19, a first boring 32-1 of the gasket 31, and a first perforation 22 of the second flange 20.

The holding bar 50 also comprises a second end portion 51-2 comprising a second securing element 52-2 to the second fixing screw 15-2. In the general embodiments described, the second securing element 52-2 is in the form of a second through hole in which is inserted the second fixing screw 15-2. The second fixing screw 15-2 is then inserted into a second opening 21-2 of the first flange 19, a second boring 32-2 of the gasket 31, and a second perforation 22-2 of the second flange 20.

The compression device 40 also comprises an intermediate portion located between the first end portion 51-1 and the second end portion 51-2. The intermediate portion comprises an intermediate portion 53 belonging to the holding bar 40, located between the first end portion 51-1 and the second end portion 51-2. The intermediate portion also comprises bearing means on the first flange 19 so as to exert pressure on the seal 31.

In the first general embodiment described with reference to FIGS. 5 to 7, the support means comprise a first threaded orifice 54-1 passing through the intermediate portion 53, and a second threaded orifice 54-2 passing through the intermediate portion 53. bearing means also comprise a first adjusting screw 55-1 screwed into the first orifice 54-1, and a second adjusting screw 55-2 screwed into the second orifice 54-2. The first adjusting screw 55-1 and the second adjusting screw 55-2 are screwed so as to pass through the orifices 54-1, 54-2, and abut against the first flange 19. The pressures exerted on the first flange 19 through the first set screw 55-1 and the second set screw 55-2 are transmitted to the joint 31. Two additional compression points on the seal 31 are thus created.

The compression device 40 also comprises a first nut 59-1 to prevent unscrewing of the first set screw 55-1. Similarly, the compression device 40 comprises a second nut 59-2 to prevent the unscrewing of the second adjusting screw 55-2.

The first end portion 51-1 and the second end portion 51-2 comprise lower faces 56-1, 56-2 in plane support with the first flange 19. In contrast, the intermediate portion 53 is not in contact with the first flange 19: the intermediate portion 53 is spaced a distance D from the first flange 19. In addition, the holding bar 50 has a flat upper face 57. Thus, the thickness E1 of the first end portion 51-1 and the thickness E2 of the second end portion 51-2, that is to say the distance between their bottom faces 56-1, 56-2 and the upper face 57, is greater than the thickness Ei of the intermediate portion 53. The holding bar 50 is generally U-shaped, both ends of which bear on the first flange 19.

The distance D, directly dependent on the thicknesses E1, E2 of the end portions 51-1, 51-2 and the thickness Ei of the intermediate portion 53, varies according to the embodiments. FIG. 6 illustrates an embodiment in which the distance is D is small, which makes it possible to limit the bulk of the holding bar 50. On the contrary, FIG. 7 illustrates an embodiment in which the distance D is more large, which allows to place insert parts 58-1, 58-2 between the adjusting screws 55-1, 55-2 and the first flange 19. The intermediate pieces 58-1, 58-2 can protect the first flange 19 of a possible marking by the adjusting screws 55-1, 55-2. The intermediate pieces 58-1, 58-2 are part of the compression device 40.

In the second general embodiment described with reference to FIG. 8, the support means comprise a first boss 80-1 and a second boss 80-2 formed by corrugations of the intermediate portion 53. More specifically, the intermediate portion 53 has two undulations whose bosses 80-1, 80,2 are formed by the vertices. However, alternatively, the intermediate portion 53 could be generally rectilinear, and the bosses 80-1, 80-2 formed by excrescences on the intermediate portion 53.

The first boss 80-1 and the second boss 80-2 are of such dimensions that they press on the first flange 19. The pressures exerted on the first flange 19 by means of the first adjusting screw 55-1 and of the second adjusting screw 55-2 is then transmitted to the joint 31. Two additional compression points on the seal 31 are thus created.

Furthermore, advantageously, in the first or second embodiment, the intermediate portion 50 comprises stiffening means, not shown in Figures 5 to 8. The stiffening means are for example ribs or bosses.

Naturally, the invention is not limited to the embodiments described with reference to the figures, and variants could be envisaged without departing from the scope of the invention. In particular, the number of threaded holes and adjusting screws in the first general embodiment, or the number of bosses in the second general embodiment, could be different. For example, in the first general embodiment, a single threaded orifice and a single adjusting screw would limit the added mass of the fastener, while a number greater than two threaded holes and two adjusting screws would improve the uniformity of the fastener. compression of the joint. The securing elements could also not be in the form of through holes, but for example in the form of fastening cables surrounding the heads of the fastening screws.

Claims (7)

1. Device for compressing (40) a seal (31) held between a first flange (19) and a second flange (20) of a turbomachine, a first fixing screw (15-1) and a second screw fastener (15-2) contributing to the fixing of the first flange (19) and the second flange (20), the compression device (40) comprising: A first end portion (51-1) comprising a first fastening element (52-1) to the first fixing screw (15-1) A second end portion (51-2) having a second securing element (52-2) to the second fixing screw (15-2) An intermediate part located between the first end portion (51-1) and the second end portion (51-2), including bearing means on the first flange (19) so as to exert pressure on the seal (31); the compression device being characterized in that the intermediate portion comprises an intermediate portion (53), and in that the support means comprise: a first orifice (54-1) threaded through the intermediate portion (53) a first screw adjusting member (55-1) adapted to be screwed into the first port (54-1) so as to press the first flange (19). 2. A compression device (40) according to the preceding claim, characterized in that the first fastening element (52-1) is a first through hole adapted to receive the first fastening screw (15-1), and the second element securing (52-2) is a second through hole adapted to receive the second fixing screw (15-2). 3. Compression device (40) according to one of claims 1 and 2, characterized in that the first end portion (51-1) and the second end portion (51-2) are of thickness (E1, E2) greater than the thickness (Ei) of the intermediate portion (53). 4. A compression device (40) according to one of claims 1 to 3, characterized in that the support means comprise a second orifice (54-2) threaded through the intermediate portion (53) and a second adjusting screw (55-2) adapted to be screwed into the second port (54-2) with an adjustable torque. 5. A compression device (40) according to one of claims 1 to 4, characterized in that the support means comprise a first nut (59-1) clamping adapted to prevent the unscrewing of the first adjusting screw ( 55-1). 6. Compression device (40) according to one of claims 1 to 5, characterized in that the support means comprise a spacer (58-1) adapted to be positioned between the adjusting screw (55-1) and the first flange (19). 7. A compression device (40) according to one of claims 1 to 6, characterized in that the intermediate portion (53) comprises stiffening means.