Seal comprising a succession of zones with and without Anti-friction coatings

Abstract

The invention relates to a seal (23) configured to be arranged between a first element (17) and a second element (11) of a propulsion assembly in an assembled configuration, the seal comprising a longitudinal sector (29) designed to be in contact with the second element (11), the longitudinal sector (29) being formed of a substantially elastic leak-tight material and comprising a first zone (31) comprising an anti-friction coating (19), a second zone (33) comprising a leak-tight coating, and a third zone (35) comprising an anti-friction coating (19), the first, second and third zones (31; 33; 35) being arranged side by side and extending longitudinally from a first end to a second end of the longitudinal sector (29).

Description

[0001] DESCRIPTION

[0002] TITLE: Seal comprising a succession of zones with and without anti-friction material coating

[0003] Technical field

[0004] The present invention relates to a seal for a propulsion unit, and more particularly to a fire and fluid seal for a propulsion unit.

[0005] The propulsion unit may be, for example, a turbojet and nacelle type unit for aircraft propulsion.

[0006] Generally speaking, the invention applies to any field requiring the installation of a fluid-tight seal, the seal being capable of being substantially set in motion.

[0007] Previous techniques

[0008] In the field of aircraft turbojet engine nacelles, various compartments are positioned close to each other, some of which may contain flammable liquids, and others of which may be exposed to fire or sparks, with the liquid not being allowed to pass from one compartment to another.

[0009] As an example, Figure 1 shows a schematic section of a nacelle 1 of a turbojet engine.

[0010] The nacelle includes a thrust reverser 3 placed downstream, as well as an engine 5 positioned in the center of the nacelle on its longitudinal axis 7.

[0011] Access to the engine 5 is via a first compartment 9, called the engine compartment. Access to said first compartment 9 is in particular by opening a movable hood 11.

[0012] The nacelle also comprises a second compartment 13 juxtaposed with the first compartment 9 and comprising equipment for controlling the thrust reverser 3.

[0013] The first compartment 9 comprises pipes comprising flammable fluids. In the event of a pipe burst incident, the fluids are released into the first compartment 9 and are likely to ignite. The first compartment 9 and the equipment inside the first compartment 9 are further designed to withstand fire, the first compartment 9 comprising, for example, automatic fire extinguishers. The released fluids are further drained to the outside through drainage holes, for example positioned in the movable cover 11.

[0014] The second compartment 13 comprises equipment which is not sized to withstand contact with the fluids of the first compartment 9, and even less to withstand a fire in said second compartment 13.

[0015] A fluid and fire-resistant seal 15 is therefore placed between these two compartments 9 and 13, one end of the seal being in particular in contact with the movable cover 11 when the latter is closed.

[0016] However, the movable cover 11, and more generally the entire nacelle 1, being subject to vibrations and movements, a coating of anti-friction material can be placed on the seal 15, thus allowing it to slide in contact with the movable cover 11, and therefore not to damage it at the risk of reducing the sealing by creating leaks.

[0017] Figure 2 schematically shows a seal 15 fixed to a first element 17 and in contact with a second element 11, for example the movable cover 11. The seal separates, for example, a first compartment 9 and a second compartment 13. A coating of anti-friction material 19 is applied to the seal 15 to facilitate sliding contact between the seal 15 and the second element 11.

[0018] However, during a pipe burst, a fraction of the anti-friction material coating 19 may be soaked with fluids 21 from the first compartment 9. By capillarity, the fluids 21 are likely to move along the seal 15 and reach the second compartment 13. This is accentuated by a pressure difference between the first compartment 9 and the second compartment 13. Consequently, the equipment in the second compartment 13 may be damaged by this infiltration of flammable fluid.

[0019] The present invention therefore aims to overcome the aforementioned drawbacks and to provide a fire- and fluid-tight seal capable, in addition, of preventing the passage of fluids by capillarity.

[0020] The present invention relates to a seal configured to be arranged between a first element and a second element of a propulsion unit in an assembled configuration, the seal comprising a longitudinal sector intended to be in contact with the second element, the longitudinal sector being formed from a substantially elastic waterproof material and comprising a first zone comprising a coating of anti-friction material, a second zone comprising a coating of waterproof material, and a third zone comprising a coating of anti-friction material.

[0021] Thus, the seal is watertight, is in frictionless sliding contact with the second element, and does not allow the passage by capillarity of a fluid at the level of the frictionless contact.

[0022] In one embodiment, the transverse width of the second zone is greater than or equal to 0.1 millimeter, preferably between 3 and 10 millimeters.

[0023] According to variants, the coating of anti-friction material is partially embedded in the waterproof material or covers the waterproof material.

[0024] Advantageously, the coating of anti-friction material comprises a synthetic fiber, preferably poly(m-phenyleneisophthalamide).

[0025] In one embodiment, the longitudinal sector comprises at least a fourth zone comprising a coating of waterproof material and a fifth zone comprising a coating of anti-friction material.

[0026] Advantageously, the waterproof material comprises a ceramic fabric and / or elastomer material.

[0027] In one embodiment, the joint comprises an "omega" type cross-section comprising a first substantially planar portion attached to the first element and a second rounded portion comprising the longitudinal sector.

[0028] In one embodiment, the second zone comprises a break splitting the second zone into two parts on either side of the break, the two parts being transversely offset.

[0029] The present invention also relates to a propulsion unit of an aircraft comprising a first compartment likely to be exposed to a fire and a second compartment, and comprising a seal as defined previously between the first compartment and the second compartment, the second zone of the seal being preferably positioned at a distance from the second compartment less than its distance from the first compartment.

[0030] The present invention also relates to an aircraft comprising a propulsion unit as defined previously and / or a joint as defined previously.

[0031] Brief description of the drawings

[0032] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0033] [Fig 1] which has already been mentioned, is a schematic sectional view of a nacelle of a propulsion unit of an aircraft according to the state of the art;

[0034] [Fig 2] is a schematic sectional view of a sealing gasket according to the state of the art;

[0035] [Fig 3A] and

[0036] [Fig 3B] are schematic views respectively in section and in perspective of an embodiment of a sealing joint according to the invention;

[0037] [Fig 4A] and [Fig 4B] are schematic views respectively in section and in perspective of a first variant of the embodiment of the sealing joint illustrated in figures 3A and 3B;

[0038] [Fig 5A] and

[0039] [Fig 5B] are schematic views respectively in section and in perspective of a second variant of the embodiment of the sealing joint illustrated in figures 3A and 3B;

[0040] [Fig 6] is a schematic perspective view of a third alternative embodiment of the seal illustrated in Figures 3A and 3B; and

[0041] [Fig 7] is a schematic perspective view of a fourth variant of the embodiment of the seal illustrated in Figures 3A and 3B.

[0042] Detailed description of at least one embodiment

[0043] Figures 3A and 3B schematically show a first embodiment of a seal 23 according to the invention.

[0044] The seal 23 is configured to be disposed between a first member 17 and a second member 11 in an assembled configuration.

[0045] The seal 23 has for example an elongated shape and comprises a cross section of type “Q” (omega) comprising a first part 25 substantially flat fixed to the first element 17 and a second part 27 rounded, and more particularly substantially tubular with a longitudinal direction which extends in the axis of this tube, a transverse direction extending perpendicular to the longitudinal direction. The sealing joint 23 can however have other shapes depending on its use.

[0046] The first element 17 is for example a wall separating a first compartment 9 and a second compartment 13 and illustrated in figure 1.

[0047] Thus, for example, the first compartment 9 provides access to an engine and is accessible from the outside by a movable cover and the second compartment 13 which is juxtaposed with the first compartment comprises equipment for controlling the thrust reverser of a nacelle of a turbojet.

[0048] In particular, the seal 23 is fixed to the first element 17 and is intended to be positioned in contact with a second element 11 in the assembled configuration. The second element 11 is for example the movable cover 11 mentioned in Figures 1 and 2.

[0049] The seal 23 separates the first compartment 9 and the second compartment 13 in a sealed manner. More particularly, the seal 23 is fluid-tight and fire-tight. The seal is, for example, included in a propulsion unit of an aircraft.

[0050] The second part 27 of the seal 23 is flexible, supple and comprises a longitudinal sector 29 intended to be in contact with the second element 11. The longitudinal sector 29 is shown flat in the figures so that the seal 23 is shown in an assembled configuration.

[0051] The second part 11 of the sealing gasket 23, and consequently also the longitudinal sector 29, is formed from a substantially elastic sealing material. The sealing material comprises, for example, a ceramic fabric and / or elastomer material, for example silicone.

[0052] Silicone provides fluid tightness and has a certain resistance to high temperatures, while its mechanical behavior is not very dependent on temperature.

[0053] In some embodiments, the waterproof material comprises glass fabric and / or carbon fabric and / or aramid fabric and / or boron fabric. Such materials, like ceramic fabrics in the broad sense, make it possible to provide a structural reinforcement function for the seal 23 and a fire seal.

[0054] The longitudinal sector 29 comprises, arranged side by side, a first zone 31 comprising a coating of anti-friction material 19, a second zone 33 comprising a coating of waterproof material, and a third zone 35 comprising a coating of anti-friction material 19. For the second zone 33, the term coating of waterproof material means a wall which is on the surface of the seal 23 and intended to be in contact with the second element 11, this coating of waterproof material being formed by exposing the waterproof material of the longitudinal sector 29, for example by removing a layer of coating of anti-friction material, or being formed by adding a coating of waterproof material to a coating of anti-friction material positioned on the longitudinal sector, the coating of anti-friction material being used for the first and third zones 31 and 35.

[0055] These three zones 31, 33 and 35 extend longitudinally over the longitudinal sector 29 from a first end to a second end (not shown). In particular, the three zones 31, 33 and 35 transversely form an alternation of zones comprising a coating of anti-friction material or a coating of waterproof material.

[0056] The coating of anti-friction material 19 makes it possible to facilitate sliding contact between the seal 23 and the second element 11. In particular, it makes it possible not to damage the sealing gasket 23 in the case of slight relative movements between the seal 23 and the second element 11.

[0057] The anti-friction material coating 19 comprises, for example, a synthetic fiber, preferably poly(m-phenyleneisophthalamide), more commonly called Nomex®.

[0058] The coating of anti-friction material 19 is for example partially embedded in the waterproof material of the seal 23 and / or covers the waterproof material so as to create an overlayer.

[0059] The second zone 33 does not comprise a coating of anti-friction material 19 so that a fluid 21 present in one of the two compartments 9 and 13, for example the first compartment 9, and moving by capillarity along the coating of anti-friction material 19 cannot pass through the second zone 33 and thus pass from one compartment to the other. For this purpose, the second zone 33 has a transverse width equal to or greater than 0.1 millimeter. Figures 4A and 4B show a first variant of the embodiment illustrated in Figures 3A and 3B. In this variant, the first zone 31 is narrower than the third zone 35 so that the second zone 33 is closer to the second compartment 13 than to the first compartment 9. In this variant, the first compartment 9 comprises a fluid 21 which can infiltrate by capillarity or by the presence of deformations 37 in the seal 23.The deformations 37 being predominant in the center of the seal 23, the positioning of the second zone 33 according to the variant illustrated in Figures 4A and 4B is favored in order to guarantee that the fluid does not pass from the first compartment 9 to the second compartment 13.

[0060] Figures 5A and 5B show a second variant of the embodiment illustrated in Figures 3A and 3B. In this variant, the longitudinal sector 29 comprises additional zones, namely a fourth zone 39 comprising a coating of waterproof material similar to the second zone 33 and a fifth zone 41 comprising a coating of anti-friction material 19 similar to the first zone 31, the fourth zone 39 and the fifth zone 41 extending longitudinally from a first end to a second end of the longitudinal sector 29. Thus, the first, second, third, fourth and fifth zones 31, 33, 35, 39 and 41 form an alternation of zones comprising a coating of anti-friction material or a coating of waterproof material. Additional zones can also be added.This variant is useful for ensuring almost certainly that the capillary movement of the fluid 21 is indeed stopped, despite the presence of deformation 37 in the sealing joint 23, deformations 37 into which fluid 21 could infiltrate.

[0061] Figure 6 shows a third variant of the embodiment illustrated in Figures 3A and 3B. In this variant, the second zone 33 is not linear and its positioning evolves along the longitudinal sector 29. In particular, certain sections of the seal 23 may be subjected to fouling or physical stresses more quickly than others. An evolving positioning of the second zone 33 makes it possible to avoid the second zone 33 being positioned on certain edges of fouled sections which are likely to lose contact with the second element 11.

[0062] Figure 7 shows a fourth variant of the embodiment illustrated in Figures 3A and 3B. In this variant, the second zone 33 comprises at least one break 43 and is split into at least two parts at said break 43. The two parts separated by the break 43 are for example offset over the width of the seal 23 so that they are not aligned longitudinally. In particular, the two parts are preferably offset transversely and not longitudinally. The first and third zones 31 and 35 are then in contact with each other at the break 43. However, the transverse displacement of a fluid by capillarity remains limited by the second zone 33, which still extends over the entire length of the longitudinal sector 29 on either side of the break 43.This variant makes it possible to simplify the manufacture of the seal 23 and also makes it possible to position the second zone 33 on particular portions of the seal 23, so as to take into account the variable crushing or fouling of the seal on certain sections.

[0063] The different variants shown can be combined with each other.

Claims

DEMANDS 1. Sealing joint (23) configured to be disposed between a first element (17) and a second element (11) of a propulsion assembly in an assembled configuration, characterized in that it comprises a longitudinal sector (29) intended to be in contact with the second element (11), the longitudinal sector (29) being formed of a substantially elastic sealing material and comprising, a first zone (31) comprising a coating of anti-friction material (19), a second zone (33) comprising a coating of sealing material, and a third zone (35) comprising a coating of anti-friction material (19).

2. Joint according to claim 1, in which the transverse width of the second zone (33) is greater than or equal to 0.1 millimeter, preferably between 3 and 10 millimeters.

3. Joint according to any one of claims 1 and 2, wherein the anti-friction material coating (19) is partially embedded in the sealing material or covers the sealing material.

4. Joint according to any one of claims 1 to 3, wherein the anti-friction material coating (19) comprises a synthetic fiber, preferably poly(m-phenyleneisophthalamide).

5. Joint according to any one of claims 1 to 4, wherein the longitudinal sector (29) comprises at least a fourth zone (39) comprising a sealing material coating and a fifth zone (41) comprising an anti-friction material coating (19).

6. Seal according to any one of claims 1 to 5, wherein the sealing material comprises a ceramic fabric and / or elastomer material.

7. Joint according to any one of claims 1 to 6, comprising an 'omega' type cross section including a first substantially flat part (25) fixed to the first element (17) and a second rounded part (27) including the longitudinal sector (29).

8. A joint according to any one of claims 1 to 7, wherein the second zone (33) comprises a rupture (43) dividing the second zone (33) into two parts on either side of the rupture (43), the two parts being offset transversely.

9. A propulsion assembly of an aircraft comprising a first compartment (9) capable of being exposed to fire and a second compartment (13), characterized in that it comprises a sealing joint (23) according to any one of claims 1 to 8 between the first compartment (9) and the second compartment (13), the second zone (33) of the joint (23) being preferably positioned at a distance from the second compartment (13) less than its distance from the first compartment (9).

10. Aircraft characterized in that it comprises a propulsion assembly according to claim 9 and / or a joint (23) according to any one of claims 1 to 8.

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