Sealing system for an aircraft propulsion unit

Abstract

The invention relates to a sealing system (18) for an aircraft propulsion unit, comprising - a seal support (20), intended to be attached to an element (16) such as a cowl, the seal support (20) comprising a central part intended to be attached to the element of the propulsion assembly, the seal support (20) comprising retaining elements (202) arranged on either side of the central part; - a sealing ring (22), comprising a base (220) covering the central part of the seal support (20), the sealing ring (22) comprising two flanks (222) extending from the base (220) so as to frame the central part of the seal support (20), each flank (222) comprising holes (224) spaced apart from one another, each hole being configured to receive one of the retaining elements (202) of the seal support (20), the cooperation between the retaining elements (202) of the seal support (20) and the lumens (224) of the sealing ring (20) establishing the reversible attachment of the sealing ring (22) to the seal support (20).

Description

Sealing system for aircraft propulsion assembly Technical Field

[0001] The present invention relates to the field of aeronautics, and more particularly to the installation of sealing gaskets in a propulsion assembly comprising a turbomachine, such as a turbofan engine. The invention more particularly concerns a sealing system comprising a sealing gasket and a gasket support. State of the art

[0002] Some aircraft have one or more propulsion units, each comprising a turbojet engine housed in a nacelle. A nacelle generally has a tubular structure extending along a longitudinal axis, and comprising a fixed upstream section consisting of an air intake upstream of the turbojet engine, a fixed mid-section intended to surround a turbojet fan, and a downstream section intended to surround the turbojet combustion chamber and which may house a thrust reverser device, the upstream and downstream sections of the nacelle being defined by reference to the direction of airflow in the nacelle in a direct jet configuration.

[0003] The role of a thrust reverser during an aircraft landing is to improve its braking capacity by redirecting at least some of the thrust generated by the turbojet engine forward. In this phase, the reverser obstructs the flow of cold air through the nacelle and directs it towards the front of the nacelle, thus generating a counter-thrust that adds to the braking force exerted by the aircraft's wheels.

[0004] The methods used to redirect the cold air flow vary depending on the type of inverter. However, in all cases, the inverter structure includes one or more movable covers that can be positioned between, on the one hand, an extended position in which they open a passage in the nacelle for the diverted flow, and, on the other hand, a retracted position in which they close this passage. These covers can perform a diversion function or simply activate other diversion mechanisms.

[0005] It is necessary to provide sealing joints in a gondola, for example to ensure sealing between certain fixed parts and certain moving parts of the gondola, such as the moving hoods of the thrust reversing device, the blower hoods, etc.

[0006] Installing seals in a propulsion system, particularly in a nacelle, can be tedious and time-consuming, especially when the seal is bonded. Furthermore, it is sometimes necessary to replace the seal, which is also a cumbersome process when it is bonded.

[0007] To reduce the installation time of sealing gaskets, adhesive-free fixing solutions have been considered, using a support to which the gasket can be reversibly attached. Such solutions are described, for example, in documents FR 3 011 881 and FR 3 088 373. The solutions described in these documents propose a gasket support with curved sections that at least partially enclose the base of the gasket. However, these solutions require a gasket with a relatively thick base, which can be a drawback for some applications. In particular, these solutions are difficult to adapt for use with a low-profile, flat gasket.

[0008] The objective of the present invention is to propose a sealing system allowing a sealing gasket to be fixed to its support without glue, and allowing the overall size to be limited. Description of the invention

[0009] To this end, the invention relates to a sealing system for an aircraft propulsion assembly, comprising: - a joint support, intended to be fixed to an element of a propulsion assembly, such as a hood, the joint support comprising a central part extending in a longitudinal direction and intended to be fixed to the element of the propulsion assembly, the joint support comprising retaining elements arranged on either side of the central part and extending in a transverse direction or in an inclined direction, in particular inclined at most 60°, relative to the transverse direction; - a sealing gasket, comprising a base extending in the longitudinal direction and covering the central part of the gasket support, the sealing gasket comprising two flanks extending from the base so as to frame the central part of the gasket support, each flank comprising lights spaced apart from each other, each light being configured to receive one of the retaining elements of the gasket support, the cooperation between the retaining elements of the gasket support and the lights of the sealing gasket ensuring the reversible fixing of the sealing gasket on the gasket support.

[0010] Thus, by providing a joint support with retaining elements and a sealing joint with lights configured to receive the return elements, the invention makes it possible to ensure reversible fixing of the joint, without gluing, while drastically limiting the overall size.

[0011] The sealing system according to the invention may include one or more of the following optional features, considered alone or in all possible combinations.

[0012] According to a characteristic, each retaining element passes through the corresponding light.

[0013] According to one characteristic, a width of the central part, measured along the transverse direction, is strictly less than the distance between the flanks of the sealing joint, so as to maintain a minimum gap between each flank and the central part of the joint support.

[0014] According to one characteristic, the clearance is greater than or equal to 1 mm.

[0015] According to one characteristic, each restraint element is arranged opposite a restraint element located on the opposite side of the central part.

[0016] According to one characteristic, the retaining elements located on either side of the central part are arranged in a staggered pattern.

[0017] Depending on one characteristic, the width of each retaining element is between 5 and 15 mm.

[0018] According to one characteristic, at least part of the retaining elements includes an assembly mark enabling an operator to detect incorrect assembly of the seal sealing, the mounting mark is configured to be concealed by the base of the seal if it is not correctly positioned, and to be visible if the base of the seal is correctly positioned.

[0019] According to one characteristic, the base of the joint has a lower surface in contact with the central part, with one or more sealing lips being provided on the lower surface.

[0020] The invention also relates to a propulsion assembly element, such as a hood, equipped with a sealing system as defined above.

[0021] The invention also relates to an aircraft propulsion assembly comprising a sealing system conforming to that defined above, the seal support being fixed to an element of the propulsion assembly, for example by gluing, screwing or crimping.

[0022] The invention also relates to an aircraft comprising at least one propulsion assembly as defined above. Brief description of the drawings

[0023] Figure 1 illustrates a propulsion assembly according to the invention, comprising a turbofan engine and a nacelle.

[0024] Figure 2 is a perspective view of a hood equipped with a sealing system according to the invention.

[0025] Figure 3 is a detail view of the hood of Figure 3 showing a portion of the seal support.

[0026] Figure 4 is a partial perspective view of a sealing system according to the invention.

[0027] Figure 5 is a schematic cross-sectional view of the sealing system attached to a structure such as the hood in Figure 3, the section being made in a plane in which the seal support does not have a retaining element.

[0028] Figure 6 is a view analogous to that of Figure 5, the section being made in a plane in which the joint support has retaining elements.

[0029] Figure 7 is a top view of a sealing system according to the invention, the seal support having mounting marks.

[0030] Figure 8 is a view analogous to that of Figure 5, showing a sealing system comprising a bubble seal.

[0031] Figure 9 is a view analogous to that of Figure 6, showing the sealing system of Figure 8. Detailed description

[0032] Figure 1 shows an aircraft propulsion unit 1. In this example, propulsion unit 1 comprises a turbomachine 2 and a nacelle 3. Propulsion unit 1 is intended to be connected via a mast to a wing (not shown) of an aircraft.

[0033] The turbomachine 2 in this example is a turbofan engine, including a gas generator and a fan. The nacelle 3 comprises a front section 10 forming an air inlet 10a, a mid-section 12 which includes two fan cowls 12a enclosing a fan casing of the turbofan engine, and a rear section 14.

[0034] The rear section 14 of the nacelle incorporates a thrust reversal system in this example. Figure 1 shows the nacelle 3 in a direct jet configuration, i.e., with the thrust reversal system inactive. The rear section 14 includes two movable cowlings 14a, the movement of which towards the rear of the nacelle activates the thrust reversal system.

[0035] Figure 2 shows a cover 16 of the propulsion assembly 1, equipped with a sealing system 18 according to the invention. The cover 16 may, for example, be a fixed or movable cover forming part of the fairing of the propulsion assembly 16, for example, a blower cover. The cover 16 may also be a cover closing an access hatch of the propulsion assembly, such as an access hatch to cylinder fittings, an oil reservoir, etc.

[0036] The sealing system 18 according to the invention comprises a seal support 20, visible in particular in figures 3 to 6, and a sealing gasket 22, visible in particular in figures 4 to 6.

[0037] The seal support 20 has a central portion 200, elongated in shape and extending along a longitudinal direction L (when the seal support is in a flat position). The central portion 200 is intended to be attached to an element of the propulsion assembly 1, such as the cowling 16 in Figure 2, for example by bonding, screwing, crimping, etc. In the example shown in the figures, the seal support 20 is attached by crimping, and more specifically by crimping using captive screw shanks 24 (one screw shank being visible in Figure 7). For this purpose, the cowling 16 and the seal support 20 each have a plurality of respective through holes 160, 201 arranged opposite each other, and intended to receive a screw shank 24. Each screw barrel 24 is fixed by crimping, so as to ensure the fixing of the seal support 20 on the hood 16. In the example, the screw barrels receive captive screws used to fix the hood 16 on the propulsion assembly 1.It is therefore necessary, as described below, that the sealing gasket 22 allows the passage of screws when it is placed on the gasket support 20.

[0038] The joint support 20 further comprises a plurality of retaining elements 202, arranged on either side of the central portion 200. Each retaining element 202 forms a projection extending from the central portion 200, either in a transverse direction T or in a direction inclined at no more than 60° to the transverse direction T. Each retaining element 202 is located below or at the level of the upper surface 200a of the central portion 200. In the example, each retaining element 202 has the shape of a tab. In the example, each retaining element 202 located on one side of the central portion 200 is positioned opposite a retaining element 202 located on the opposite side of the central portion 200. Alternatively, a staggered arrangement may be considered.

[0039] The retaining elements 202 of the gasket support 20 are configured to retain the sealing gasket 22 when it is placed on the gasket support 20, as shown in particular in Figures 4 to 6. The sealing gasket 22 according to the invention comprises a base 220, intended to cover the central portion 200 of the gasket support 20 as well as a portion of each retaining element 202. The base 220 has an elongated shape along the longitudinal direction L. The sealing gasket 22 has two flanks 222, each flank 222 extending from the base 220 in a direction perpendicular to the longitudinal L and transverse T directions of the base 220, so as to frame the central portion 200 of the gasket support 20. Each flank 222 has openings 224, each opening 224 being designed to be traversed by a corresponding retaining element 202 of the gasket support 20, as shown in Figures 4 and 6. Thus, the interaction between the retaining elements 202 of the gasket support 20 and the openings 224 in the flanks 222 of the seal 22 allows for a robust fixing of the seal 22 to the gasket support 20, this fixing being reversible. Therefore, the seal 22 can be fixed to the gasket support 20 without the need for adhesive. Of course, ensuring the assembly and disassembly of the sealing gasket 22 on the gasket support 20 requires the deformation of certain parts of the sealing gasket 22, including in particular the flanks 222.The sealing gasket 22 will therefore be made of a material with the required flexibility and elasticity. For example, the sealing gasket can be made of an elastomeric material, such as silicone, rubber, neoprene, etc. The retaining elements 202 of the gasket support 20 are sufficiently rigid to ensure the necessary retention of the sealing gasket. The gasket support 20 will preferably be made of a material with the required rigidity, for example, a metallic material (steel, aluminum or titanium alloy, etc.), a plastic material, or a composite material.

[0040] The shape and dimensions of each light 224 provided on the sealing joint are compatible with the shape and dimensions of the corresponding retaining element 202.

[0041] Advantageously, the width L1 of the central portion 200 is strictly less than the distance L2 between the flanks 222 of the sealing gasket 22. This configuration ensures a minimum clearance J between the inner face of each flank 222 and the central portion 200, thus preventing the central portion 200 from exerting undesirable mechanical stresses on the flanks 222. By providing a minimum clearance J, the correct positioning of the gasket on its support is therefore ensured, without inducing undesirable deformations that would affect the sealing provided by the gasket. The clearance J will, for example, be greater than or equal to 1 mm.

[0042] Advantageously, the width L3 of each retaining element is strictly greater than the distance L4 between the outer face of each side 222 and the central part 200. This ensures that each retaining element passes through the corresponding opening 224, thus promoting optimal retention of the sealing gasket 22 on the gasket support 20. As an example, the width L3 is between 5 and 15 mm.

[0043] In the example of Figures 2 to 7, the sealing gasket 22 is a flat type gasket. The base 220 thus has a predominantly flat upper surface 226, and in the example has sealing lips 226a, or grooves 226a, extending outwards from the upper surface 226.

[0044] Advantageously, a lower surface 228 of the base 220, opposite the upper surface 226 and in contact with the central part 200 of the joint support 20, has one or more sealing lips 228a, or grooves 228a, to ensure sealing between the sealing joint 22 and the joint support 20.

[0045] Advantageously, as can be seen in Figure 7, which partially depicts the cover 16 and the sealing system according to the invention viewed from above, the retaining elements 202 may include a mounting mark 202a, enabling an operator to verify that the sealing gasket 22 is correctly installed on the gasket support 20. In the example, the mounting marks 202a take the form of a long line parallel to the longitudinal direction L. The mounting mark allows the operator to determine whether the sealing gasket 22 is correctly or incorrectly positioned relative to the gasket support 20. Thus, the sealing gasket 22 is correctly centered if the mounting marks 202a are visible from both sides of the gasket support 20, which is not the case in Figure 7, since the mounting marks 202a are not visible from the left side of the figure, as they are concealed by the sealing gasket 22.

[0046] As can also be seen in figure 7, the sealing gasket 22 has, at the right of each screw shaft 24, a through hole 221 provided in the base 220. The holes 221 allow the passage of the screws ensuring the attachment of the hood 16 to the propulsion assembly 1.

[0047] Figures 8 and 9 are views analogous to those of figures 5 and 6, showing a sealing system according to the invention, in which the sealing joint 22 is a bubble seal.

[0048] The system according to the invention allows for the reversible fixing of a sealing gasket, without the use of adhesive, and while maintaining a very low profile. For example, the height H of the sealing system 18 shown in Figures 5 and 6 can be less than 5 mm.

[0049] Preferably, the spacing between two adjacent retaining elements 202 located on the same side of the central part 200 will be between 50 and 100 mm.

Claims

Demands

1. Sealing system (18) for an aircraft propulsion assembly, comprising: a seal support (20), intended to be attached to an element (16) of a propulsion assembly, such as a cowling, the seal support (20) having a central portion (200) extending in a longitudinal direction (L) and intended to be attached to the element of the propulsion assembly, the seal support (20) having retaining elements (202) arranged on either side of the central portion (200) and extending in a transverse direction (T) or in an inclined direction, in particular inclined at most 60°, with respect to the transverse direction (T);a sealing gasket (22), comprising a base (220) extending along the longitudinal direction (L) and covering the central part (200) of the gasket support (20), the sealing gasket (22) comprising two flanks (222) extending from the base (220) so as to frame the central part (200) of the gasket support (20), each flank (222) comprising openings (224) spaced apart, each opening being configured to receive one of the retaining elements (202) of the gasket support (20), the cooperation between the retaining elements (202) of the gasket support (20) and the openings (224) of the sealing gasket (20) ensuring the reversible attachment of the sealing gasket (22) to the gasket support (20).

2. Sealing system (18) according to the preceding claim, wherein each retaining element (202) passes through the corresponding light (224).

3. Sealing system (18) according to any one of the preceding claims, wherein a width (L1) of the central part (200), measured along the transverse direction (T), is strictly less than the distance (L2) between the flanks (222) of the sealing joint (22), so as to maintain a minimum clearance (J) between each flank (222) and the central part (200) of the joint support (20).

4. Sealing system (18) according to the preceding claim, wherein the gap (J) is greater than or equal to 1 mm.

5. Sealing system (18) according to any one of the preceding claims, wherein each retaining element (202) is arranged opposite a retaining element (202) located on the opposite side of the central part (200).

6. Sealing system (18) according to any one of claims 1 to 4, wherein the retaining elements (202) located on either side of the central part (200) are arranged in a staggered pattern.

7. Sealing system (18) according to any one of the preceding claims, wherein the width (L3) of each retaining element (202) is between 5 and 15 mm.

8. Sealing system (18) according to any one of the preceding claims, wherein at least a portion of the retaining elements (202) includes a mounting mark (202a) enabling an operator to detect incorrect mounting of the sealing gasket (22), the mounting mark (202a) being configured to be concealed by the base (220) of the gasket (22) if the latter is not correctly positioned and to be visible if the base (220) of the gasket (22) is correctly positioned.

9. Sealing system (18) according to any one of the preceding claims, wherein the base (220) of the seal (22) has a lower surface (228) in contact with the central part (200), one or more sealing lips (228a) being provided on the lower surface (228).

10. Aircraft propulsion assembly comprising a sealing system (18) according to any one of the preceding claims, the seal support (20) being fixed to an element (16) of the propulsion assembly, for example by gluing, screwing or crimping.

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