Fluid circuit including a connecting fitting for double-walled pipes and associated process

Abstract

A fluid circuit (FC), particularly for aircraft, comprising a connecting fitting (3) made of thermoplastic material, for sealingly connecting two pipes (A, B), the connecting fitting (3) comprising: an inner connecting conduit (33) configured to fluidly connect a tube (TA) of the first pipe (A) and an inner tube (TI-B) of the second pipe (B), and a one-piece outer connecting conduit (34) configured to cooperate with an outer tube (TE-B) of the second pipe (B), the inner connecting conduit (33) being enclosed in the outer connecting conduit (34) and being mounted at a determined position in the outer connecting conduit (34) to allow a blind connection of the inner connecting conduit (33) with the inner tube (TI-B) of the second pipe (B) when connecting the outer connecting conduit (34) with the outer tube (TE-B) of the second pipe (B).Figure from the summary: Figure 4.

Description

Title of the invention: Fluid circuit comprising a connecting fitting for double-walled pipes and associated method. Technical field

[0001] The present invention relates to the field of fluid circuits in an aircraft, for example, a drinking water circuit, a wastewater circuit, a drainage circuit, etc. The invention relates in particular to the connection of pipes in such a fluid circuit.

[0002] As is known, a fluid circuit comprises a plurality of pipes mechanically and fluidically connected to each other. When installing a fluid circuit in an aircraft, the pipes are independently attached to the aircraft structure and then fluidically connected to each other. To connect a first pipe to a second pipe, it is known to use a connecting fitting, which must be mounted at the interface between the first and second pipes to ensure a leak-proof connection. Connecting fittings that allow the connection of three pipes are also known and are referred to as "T-fittings."

[0003] In order to reduce the mass of an aircraft, pipes are increasingly being manufactured from a thermoplastic material, and more specifically from a polymer known as PEEK (for polyetheretherketone), which allows the manufacture of semi-rigid, lightweight, and robust pipes. Such a pipe also has a thin wall thickness.

[0004] In practice, in an aircraft, the potable water system is installed within the aircraft structure and may pass through areas containing electrical equipment. To prevent any risk of water leakage onto the electrical system, it is necessary for the pipes to be double-walled. Such a pipe is commonly referred to as a "double-walled pipe" and, as such, comprises an outer tube and an inner tube mounted inside the outer tube.

[0005] With reference to [Fig. 1], a connecting fitting 101 is known in the prior art for connecting a first double-walled pipe A to a second double-walled pipe B, each being made of thermoplastic material. Such a connecting fitting 101 comprises a connecting element 102 that joins the inner tubes TI of the two pipes A, B and an outer casing 103 that connects the outer tubes TE and ensures a seal in the event of a leak in the connecting element 102. [Fig. 2] similarly illustrates the connection of three pipes A, B, C by means of a T-shaped connecting fitting 101 of the prior art. a significant mass. It is equipped with several fasteners 104 that must be manipulated by the operator during closure. In practice, to ensure a leak-proof connection, the connecting element 102 must be firmly locked, which requires applying a significant tightening torque to each fastener 104 using a tool, thus increasing the physical strain on the operators. Furthermore, the use of tools is impractical, particularly in an aircraft fluid circuit that may require several hundred connecting fittings. Moreover, handling tools presents a risk to the operator working in a confined space.

[0007] Furthermore, as described previously, to ensure the watertightness of the connecting fitting 101, an outer casing 103 is added, allowing the outer tubes TE of the pipes A and B to be connected. This outer casing 103 comprises two half-shells that are sealed with resin, which again presents the disadvantage of being time-consuming and complex to implement. Moreover, the outer casing 103 significantly increases the size of the connecting fitting 101, which is undesirable in an aircraft where space is limited and each connection is difficult to access.

[0008] In summary, installing the connecting fitting is time-consuming, impractical, and increases the cost of installing a fluid circuit. Currently, there is no lightweight and compact connecting fitting available that allows for the connection of double-walled pipes made of thermoplastic material.

[0009] The invention thus aims to eliminate at least some of these drawbacks by providing a lightweight and compact connecting fitting that allows two double-walled thermoplastic pipes to be connected simply, quickly, and conveniently. The invention is particularly suited to connecting at least two thermoplastic pipes, at least one of which is a double-walled pipe. PRESENTATION OF THE INVENTION

[0010] The invention relates to a fluid circuit, in particular for aircraft, comprising: • at least one first thermoplastic material pipe comprising a connection end including a connector, hereinafter "first connector", the first pipe comprising at least one tube, • at least one second pipe made of thermoplastic material comprising a connecting end including a connector, hereinafter referred to as the "second connector", the second pipe comprising an outer tube and an inner tube mounted within the outer tube, the first and second pipes extending along a longitudinal axis, and • a thermoplastic connecting fitting, for a watertight connection between the two connection ends, comprising: • at least one first connection end configured to be mechanically connected to the first connector, • at least one second connection end configured to be mechanically connected to the second connector, • an internal connecting conduit configured to fluidly connect at least the tube of the first pipeline and the internal tube of the second pipeline, • an external connecting conduit configured to cooperate with at least the external tube of the second pipeline, the external connecting conduit being a single piece, • the inner connecting duct being enclosed within the outer connecting duct so as to prevent any separation of the inner connecting duct and the outer connecting duct, the inner connecting duct being mounted in a determined position within the outer connecting duct so as to allow a connection of the inner connecting duct with at least the inner tube of the second duct in a blind manner when connecting the outer connecting duct with at least the outer tube of the second duct.

[0011] The term "imprisoned" means that the inner conduit is mounted within the outer conduit in a way that cannot be lost. In other words, the inner connecting conduit and the outer connecting conduit are inseparable.

[0012] The connecting fitting according to the invention allows for the simple and practical connection of two thermoplastic pipes, at least one of which is a double-walled pipe. The inner and outer tubes of the double-walled pipe can be connected simultaneously to the connecting fitting, allowing for a blind connection of the connecting fitting's inner conduit to the inner tube of the pipe when the connecting outer conduit is connected to the outer tube of the pipe, both of which are visible to the operator. In other words, unlike the prior art, it is not necessary to connect the inner and outer conduits successively and independently, resulting in significant time savings. This is particularly advantageous in an aircraft fluid circuit that includes a large number of connecting fittings.

[0013] A one-piece connecting fitting comprising an inner connecting conduit and an outer connecting conduit joined together is advantageously compact, also allowing a single piece to be stored and handled, which is convenient.

[0014] The thermoplastic connecting fitting has the advantage of being lightweight and It is easily handled by an operator. Furthermore, a thermoplastic fitting can be easily attached manually by an operator without requiring special tools, thus reducing the physical strain. This is also a significant advantage in an aircraft, where space is limited and connecting fittings are often difficult to access. In addition, its cost is considerably reduced, which is beneficial.

[0015] In one embodiment, the fluid circuit includes at least one spacer mounted between the inner connecting conduit and the outer connecting conduit, so as to mechanically connect them, the connecting fitting forming a single unit. The spacer allows the connecting ends of the connecting element to be precisely positioned opposite the tubes of each pipe, without the inner connecting conduit moving within the outer connecting conduit. In other words, the spacer allows the inner connecting conduit to be placed in a predetermined relative position with respect to the outer connecting conduit, thus enabling the simultaneous connection of the inner and outer tubes of a double-walled pipe.

[0016] Preferably, the fluid circuit comprises a plurality of spacers mounted between the inner connecting conduit and the outer connecting conduit, the spacers of the plurality of spacers being distributed around the inner connecting conduit to allow stable and balanced support.

[0017] Preferably, the connecting fitting is made of a thermoplastic material selected from polyetheretherketone and glass fiber-reinforced polyamides, resulting in a lightweight connecting fitting for double-walled pipes that reduces operator strain. Preferably, the connecting fitting is made of polyetheretherketone or a polyamide reinforced with 30% glass fibers, providing a connection that is both lightweight and robust.

[0018] In one embodiment, the tube of the first pipeline being an inner tube, the first pipeline comprising an outer tube, the inner tube being mounted in the outer tube, the inner connecting conduit of the connecting fitting is configured to fluidly connect the inner tube of the first pipeline and the inner tube of the second pipeline, and the outer connecting conduit is configured to connect the outer tube of the first pipeline and the outer tube of the second pipeline.The connecting fitting can thus advantageously join two double-walled pipes simply and quickly by allowing both a simultaneous connection of the inner and outer connecting conduits to the inner and outer tubes of the first pipe, respectively, and a simultaneous connection of the inner and outer connecting conduits to the inner and outer tubes of the second pipe, respectively. In summary, the connecting fitting allows two double-walled pipes to be joined. thermoplastic material in a simple and practical way.

[0019] In one embodiment, the fluid circuit comprises a third pipe made of thermoplastic material extending along a lateral axis orthogonal to the longitudinal axis, the third pipe comprising at least one tube, the third pipe comprising a connecting end including a connector, hereinafter referred to as the "third connector," the connecting fitting comprising a third connecting end configured to be mechanically connected to the third connector, the internal connecting conduit being configured to fluidly connect the tube of the first pipe, the internal tube of the second pipe, and the tube of the third pipe. The connecting fitting allows three pipes, one, two, or all three of which are double-walled pipes made of thermoplastic material, to be connected in a simple and practical manner.In the case of connecting three double-walled pipes, the inner connecting duct and the outer connecting duct are advantageously connected simultaneously to the inner and outer tubes of each pipe, respectively.

[0020] Preferably, the inner connecting conduit and the outer connecting conduit have a "T" shape in which the inner connecting conduit is enclosed within the outer connecting conduit. The connection of three thermoplastic pipes can be conveniently achieved, and the fitting can be easily installed in a fluid circuit of an aircraft with a congested environment.

[0021] The invention also relates to an aircraft comprising at least one fluid circuit as described above.

[0022] Finally, the invention relates to a method for connecting at least one first pipe and a thermoplastic connecting fitting of a fluid circuit as described above, the method comprising at least the steps of: • connecting the outer connecting conduit of the connecting fitting with at least the outer tube of the second pipe, and • simultaneously, blindly connect the inner connecting conduit with at least the inner tube of the second pipe. PRESENTATION OF THE FIGURES

[0023] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0024] Fig. 1 is a schematic representation of a connecting fitting according to the prior art for connecting two pipes.

[0025] Figure 2 is a schematic representation of a connecting fitting according to Article previous for the connection of three pipes.

[0026] The [Fig.3] is a schematic exploded view representation of a fluid circuit according to one embodiment of the invention.

[0027] Fig. 4 is a cross-sectional view of a schematic representation of a connecting fitting according to one embodiment of the invention for connecting a single-wall pipe and a double-wall pipe.

[0028] Fig. 5 is a cross-sectional view of a schematic representation of a connecting fitting according to one embodiment of the invention for connecting two double-walled pipes.

[0029] Fig. 6 is a schematic representation of a connecting fitting according to one embodiment of the invention for connecting three double-walled pipes.

[0030] Fig. 7 is a close-up cross-sectional view of the connecting fitting of Fig. 6.

[0031] Fig. 8 is a diagram of the steps of a method for connecting two pipes according to an embodiment of the invention.

[0032] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0033] A fluid circuit according to the invention intended to be mounted in an aircraft, in particular for the transport of water, will be presented; however, it is understood that the fluid circuit could just as easily allow the transport of a different fluid, such as fuel or gases.

[0034] As is known, a fluid circuit comprises a plurality of pipes that are connected to one another to guide a fluid. The invention will initially be presented for the connection of two pipes in a fluid circuit. However, the invention also applies to the connection of more than two pipes, as will be described later.

[0035] With reference to [Fig. 3], an exploded view of a fluid circuit CF according to one embodiment of the invention is shown. The fluid circuit CF comprises a first pipe A, a second pipe B, mounted opposite each other, and a connecting fitting 3, intended to be mounted at the interface between the first pipe A and the second pipe B, in order to connect them fluidly.

[0036] In this example, the first pipe A and the second pipe B extend longitudinally along an axis X, laterally along an axis Y, and vertically along an axis Z, so as to form an orthogonal coordinate system (X, Y, Z). Therefore, the term "vertical" describes an object extending in the (Y, Z) plane and the term "Horizontal" means an object that extends in the (X, Y) plane. Similarly, the terms "front" and "rear" refer to the longitudinal axis X that extends from the first pipe A to the second pipe B from back to front, according to the direction of flow of a fluid from back to front.

[0037] According to one aspect of the invention, the first pipe A and the second pipe B are made of a thermoplastic polymer material. In this example, each pipe A, B is preferably made of polyetheretherketone, commonly referred to by the acronym PEEK (meaning PolyEtherEtherKetone in English).

[0038] With reference to [Fig. 4], which shows a longitudinal cross-sectional view of the assembled CF fluid circuit, the first pipe A comprises, in this example, a tube TA, forming a single-wall pipe. The second pipe B comprises an outer tube TE-B and an inner tube TLB, mounted inside the outer tube TE-B. The inner tube TLB and the outer tube TE-B are concentric and form a double-wall pipe. Each tube TA, TE-B, TLB extends along the longitudinal axis X. A first example is described in which the first pipe A is a single-wall pipe. In a second embodiment shown in [Fig. 5], the first pipe A also comprises an outer tube TE-A and an inner tube TLA mounted inside the outer tube TE-A, the inner tube TLA and the outer tube TE-A of the first pipe A being concentric and forming a double-wall pipe.In other words, the connecting fitting 3 according to the invention allows the connection of at least two pipes A, B, of which at least one is a double-walled pipe.

[0039] In this example, each tube TA, TE-B, TLB has a cylindrical shape. Preferably, the tubes TA, TE-B, TLB have the shape of a right circular cylinder, as shown in the figures. However, it is understood that the tubes may have a different shape, for example, the shape of a cylinder with a square or rectangular base. Each tube TA, TE-B, TLB comprises a cylindrical inner surface extending radially inward within said tube TA, TE-B, TLB and a cylindrical outer surface extending radially outward from the tube TA, TE-B, TLB. In this example, the inner surface of the inner tube TLB of the second pipeline B and the inner surface of the tube TA of the first pipeline A are intended to come into contact with the fluid.

[0040] As shown in [Fig.4], to allow connection, the inner tube TI of each double-walled pipeline A, B has a length along the longitudinal axis X greater than the length of the outer tube TE.

[0041] In this embodiment, each pipe A, B has a connecting end Al, Bl. The two connecting ends Al, B1 are intended to be connected via the connecting fitting 3. More specifically, as shown in Figures 3 and 4, each connection end Al, B1 includes a connector 1, 2 which cooperates with the connecting fitting 3. Hereafter, for clarity, the connector 1 mounted on the connection end Al of the first pipe A will be designated "first connector" 1 and the connector 2 mounted on the connection end B1 of the second pipe B will be designated "second connector" 2.

[0042] With further reference to Figures 3 and 4, each connector 1, 2 has a tubular shape and is configured to cooperate, by complementary shapes, with each pipe A, B respectively. In this example, each connector 1, 2 cooperates respectively with the outer surface of the TA tube of the first pipe A and with the outer surface of the TE-B outer tube of the second pipe B. In practice, each connector 1, 2 has dimensions adapted to cooperate with the pipe on which it is mounted. In other words, the first connector 1 and the second connector 2 have similar shapes with a diameter adapted to fit onto the connection end Al, B1 of a single-wall or double-wall pipe.

[0043] In this respect, in this example, the first connector 1 mounted on the single tube TA of the first pipeline A has a diameter DI smaller than the diameter D2 of the second connector 2 mounted on the outer tube TB of the second pipeline B. In the case of connecting two double-walled pipelines A and B, the two connectors 1 and 2 are identical to the second connector 2, as shown in [Fig. 5]. The two connectors 1 and 2 then preferably have identical dimensions.

[0044] In particular, each connector 1, 2 comprises a socket portion 11, 21, mounted on the connecting end A1, B1, and a link portion 12, 22 configured to cooperate with the link fitting 3. The link portion 12, 22 is configured to cooperate with the link fitting 3, for example, by a socket joint. In this example, the link portion 12 has an external radial diameter D12 shown in [Fig. 4].

[0045] With reference to Figures 3 and 4, each connector 1, 2 comprises, in this example, a connecting flange 13, 23, which extends radially from the connecting portion 12, 22. The connecting flange 13, 23 is configured to allow connection with the connecting fitting 3, as will be described in more detail later. In this example, the connecting flanges 13, 23 have a diameter De.

[0046] Preferably, each connector 1, 2 comprises on the connecting portion 12, 22 a radial groove 15, 25 for receiving a sealing gasket J (shown in [Fig. 4]), configured to be sandwiched between the connector 1, 2 and the fitting of connection 3, in order to limit any risk of leakage in the fitting.

[0047] To connect each pipe A, B to the connecting fitting 3, each connector 1, 2 includes a locking member 5 and a securing member 6.

[0048] The locking member 5 is configured to provide axial locking along the longitudinal axis X of the connector 1, 2 and the connecting fitting 3 relative to the connection end A1, B1 of the pipeline A, B. In this example, the locking member 5 is configured to lock the connector 1, 2 and the connecting fitting 3 by clipping, as will be described in more detail later. It is understood that the locking could be achieved differently, for example by screwing.

[0049] The locking element 6 is configured to prevent the locking element 5 from being removed, thus preventing any accidental disconnection of the connecting fitting 3 and the pipe A, B. In this example, the locking element 6 is configured to be connected to the locking element 5 by clipping it in place to allow for a quick and easy connection. It goes without saying that the connection could be secured in a different way, for example by screwing.

[0050] As described previously, the connecting fitting 3 allows the connection end Al of the first pipe A via the first connector 1 to be sealed together and the connection end B1 of the second pipe B via the second connector 2.

[0051] According to one aspect of the invention, the connecting fitting 3 is made of a thermoplastic material, thereby reducing its mass and cost. In particular, the connecting fitting 3 is preferably made of polyetheretherketone, commonly referred to by the acronym PEEK (for PolyEtherEtherKetone). Such a PEEK material is a semi-crystalline, thermostable thermoplastic with high mechanical properties and resistance to high temperatures. Alternatively, the connecting fitting 3 is made of glass fiber-reinforced polyamide, and in particular of polyamide reinforced with 30% glass fibers.

[0052] As described previously, [Fig. 4] shows a cross-sectional view of the connecting fitting 3 for connecting a first single-walled pipe A and a second double-walled pipe B. Similarly, [Fig. 5] shows a cross-sectional view of the connecting fitting 3 for connecting two double-walled pipes A and B.

[0053] The connecting fitting 3 has a first connecting end 31, configured to be mechanically connected to the first connector 1, and a second connecting end 32 configured to be mechanically connected to the second connector 2. The connecting fitting 3 extends longitudinally along the X-axis for connecting two pipes A, B. For connecting three pipes A, B, C (as shown in Figures 6 and 7), the connecting fitting 3 includes also a third connecting end 37 configured to cooperate with a third connector 4 mounted on a connecting end Cl of a third pipeline C. In this embodiment, the connecting fitting 3 preferably has a T-shape, as will be described in more detail later.

[0054] According to one aspect of the invention, with reference to [Fig. 4], the connecting fitting 3 comprises an outer connecting conduit 34 and an inner connecting conduit 33 mounted within the outer connecting conduit 34. Preferably, the inner connecting conduit 33 and the outer connecting conduit 34 are concentric. Hereafter, for the sake of brevity, the inner connecting conduit 33 will be referred to as the "inner conduit 33" and the outer connecting conduit 34 will be referred to as the "outer conduit 34".

[0055] In this example, the inner conduit 33 is configured to fluidly connect the TA tube of the first pipeline A and the TI-B inner tube of the second pipeline B. The outer conduit 34 is configured to be connected to the TE-B outer tube of the second pipeline B. At the first connection end 31, the outer conduit 34 is blind in this example, since the first pipeline A is a single-wall pipeline. In the case of connecting two double-wall pipelines (as shown in [Fig. 5]), the outer conduit 34 is configured to be connected to the TE-A outer tube of the first pipeline A and to the TE-B outer tube of the second pipeline B to fluidly connect them. The inner conduit 33 and the outer conduit 34 form a double-wall connecting fitting 3 which ensures safety even in the event of a leak in the inner conduit 33.

[0056] In practice, the outer conduit 34 is connected to the outer tube TE-B of the second pipeline B via the second connector 2, and the inner conduit 33 is connected to the tube TA of the first pipeline A via the first connector 1. The inner conduit 33 is also, in this example, directly connected to the inner tube TLB of the second pipeline B. In this example, the inner conduit 33 is fitted around the inner tube TLB of the second pipeline B. As such, the inner conduit 33 preferably has an inner diameter D33 substantially equal (i.e., within a fitting clearance) to the outer diameter DB of the inner tube TLB of the second pipeline B (as shown in [Fig. 4]). Preferably, a sealing gasket J (shown in [Fig. 4]) is sandwiched between the inner tube TLB of the second pipeline B and the inner conduit 33 of the connecting fitting 3, so as to form a leak-proof connection.

[0057] In this example, the inner conduit 33 and the outer conduit 34 have a tubular shape. Preferably, the connecting conduits 33, 34 have the shape of a right circular cylinder, so as to cooperate by complementary shape with one of the connectors 1, 2 and / or the inner tube TLB of the second conduit B. It goes without saying that the connecting conduits 33, 34 could alternatively have a a different shape, for example, the shape of a cylinder with a square or rectangular base.

[0058] The inner conduit 33 is preferably a single piece. In this example, the inner conduit 33 is manufactured by molding, that is, by injecting thermoplastic in a press. It goes without saying that the manufacturing process could be different.

[0059] According to one feature of the invention, the outer duct 34 is a single piece. In this example, the outer duct 34 is manufactured by overmolding thermoplastic material onto the inner duct 33.

[0060] According to one aspect of the invention, the inner conduit 33 is trapped within the outer conduit 34, so as to prevent any separation of the inner conduit 33 and the outer conduit 34. By the term "trapped," it is understood that the inner conduit 33 is trapped within the outer conduit 34, that it is mounted in a non-removable manner within the outer conduit 34. In other words, the inner conduit 33 and the outer conduit 34 are inseparable.

[0061] With further reference to [Fig. 4], the inner conduit 33 and the outer conduit 34 are precisely mounted relative to each other. More specifically, the inner connecting conduit 33 is mounted in a specific position within the outer connecting conduit 34 so as to ensure the connection of the inner conduit 33 with the inner tube TLB of the second pipeline B when the outer conduit 34 is connected to the outer tube TE-B of the second pipeline B via the second connector 2. In other words, thanks to the precise positioning between the inner conduit 33 and the outer conduit 34, the inner conduit 33 is configured to automatically fit around the inner tube TLB of the second pipeline B when the outer conduit 34 and the outer tube TE-B are connected.

[0062] In the case of connecting two double-walled pipes, the precise positioning of the inner duct 33 in the outer duct 34 ensures the connection of the inner duct 33 with the inner tube TLA of the first pipe A and with the inner tube TLB of the second pipe B when connecting the outer duct 34 respectively with the outer tube TE-A of the first pipe A and with the outer tube TE-B of the second pipe B.

[0063] To this end, as shown in [Fig. 4], the connecting fitting 3 comprises, in one embodiment, a spacer 8 mounted between the inner duct 33 and the outer duct 34, so as to mechanically connect them. The spacer 8 allows, in the case of a connection of two double-walled pipes, the formation of a single-piece connecting fitting 3. In this example, the spacer 8 has a height h, defined between the inner duct 33 and the outer duct 34 as being between 12.7 and 25.4 x 10³ m, so as to center the inner duct 33 within the outer duct 34 to allow homogeneous flow in the outer duct 34. Preferably, the connecting fitting 3 comprises a plurality of spacers 8 distributed circumferentially tiellement around the inner duct 33, to ensure optimal support.

[0064] For connecting a single-wall pipe to a double-wall pipe, the outer conduit 34 is preferably blind-ended and is connected to the inner conduit 33, forming a single unit, as shown in [Fig. 4]. In this embodiment, one or more spacers 8 may also be added.

[0065] As described previously, the first connecting end 31 is configured to be mechanically connected to the first connector 1, and the second connecting end 32 is configured to be mechanically connected to the second connector 2. To this end, each connecting end 31, 32 has a cylindrical shape to cooperate by complementary shape with the connecting portion 12, 22 of the oppositely mounted connector 1, 2. It is understood that the shape of the connecting end 31, 32 could be different to cooperate with a connector 1, 2 that has a different shape; the important point is that the connecting portion 12, 22 of the connector 1, 2 and the opposite connecting end 31, 32 have complementary shapes.

[0066] In particular, each connecting end 31, 32 defines an inner cylindrical surface intended to be in contact with an outer surface of the connecting portion 12, 22 of the connector 1, 2. Indeed, again with reference to [Fig. 4], each connecting end 31, 32 is configured to be mounted opposite the connecting portion 12, 22 of the connector 1, 2 by interlocking. In other words, the first connecting end 31 preferably has an inner diameter D31 substantially equal to the outer diameter D12 of the connecting portion 12, 22 of the connector 1, 2 to allow them to cooperate while limiting the risk of leakage. By "substantially equal", we mean here that the inner diameter D31 of the first connecting end 31 is slightly greater than the outer diameter D12 of the connecting portion 12, 22 of the connector 1, 2 to allow the two parts to fit together, without too much play existing between the two.A connection by interlocking is described; however, it is understood that each connecting end 31, 32 could cooperate with the connecting portion 12, 22 of the opposite connector 1, 2 in a different way.

[0067] In this example, the free end of each connecting end 31, 32 comprises a connecting flange 35, 36 that extends radially. The connecting flange 35, 36 is configured to be pressed against the connecting flange 13, 23 along the longitudinal axis X to mechanically connect each connecting end 31, 32 to each respective connector 1, 2. For this purpose, the connecting flanges 35, 36 have a diameter Dr (shown in [Fig. 3]) similar to the diameter De of the connecting flanges 13, 23.

[0068] To lock the connecting fitting 3 with each connector 1, 2, the locking member 5 mentioned previously is configured in this example to jointly lock each connecting flange 35, 36 with the opposite connecting flange 13, 23 to prevent any axial movement. In this example, the locking is achieved by clipping. The securing member 6 is configured in this example to prevent the flanges from separating. Preferably, the securing member 6 is configured to radially overlap the locking member 5 to prevent accidental unclipping. It goes without saying that the locking of the connecting fitting 3 on each connector 1, 2 and the securing of the connection could be achieved in a different way.

[0069] In one embodiment, as described above, the fluid circuit CF comprises a first pipe A, a second pipe B, a third pipe C, and a connecting fitting 3 intended to be mounted at the interface between the three pipes A, B, and C to connect them fluidly. The three pipes A, B, and C and the connecting fitting 3 are made of a thermoplastic material.

[0070] In this example shown in [Fig.6], the third pipe C extends longitudinally along the vertical axis Z, so as to be positioned perpendicular to the first pipe A and the second pipe B, which are themselves mounted opposite each other.

[0071] In this example, each pipe A, B, C comprises an outer tube TE-A, TE-B, TE-C and an inner tube TLA, TLB, TLC, mounted respectively inside each outer tube TE-A, TE-B, TE-C. It is understood that the connecting fitting 3 could equally well connect three pipes, only one of which would be a double-walled pipe, the other two being single-walled pipes. The invention also applies to the connection of two double-walled pipes and one single-walled pipe. Similarly, it is understood that the connecting fitting 3 could also allow the connection of four pipes, at least one of which would be a double-walled pipe.

[0072] In a manner analogous to the first pipe A and the second pipe B, the third pipe C has a connection end Cl which includes a connector 4, designated "third connector" 4. The third connector 4 is analogous to the second connector 2 described previously, configured to be mounted at one end of a double-walled pipe.

[0073] In this example, the connecting fitting 3, a close-up cross-sectional view of which is shown in [Fig. 7], has a "T" shape and comprises a first connecting end 31 configured to cooperate with the first connector 1 mounted on the connecting end A1 of the first pipe A, and a second connecting end 32 configured to cooperate with the second connector 2. mounted on the B1 connection end of the second pipe B and a third connection end 37 configured to cooperate with the third connector 4 mounted on the Cl connection end of the third pipe C.

[0074] Similar to the connection of two pipes A, B, the connecting fitting 3 is preferably a single unit. In other words, the inner conduit 33, which has a T-shape, is mounted in a trapped manner within the outer conduit 34, which also has a T-shape.

[0075] The third connector 4 then includes a locking member 5 and a securing member 6 to lock the third conduit C and the third connecting end 37 of the connecting fitting 3.

[0076] A method for connecting a first pipe A and a second pipe B, with reference to [Fig. 8], according to an embodiment of the invention, will now be described. In this example, the first pipe A and the second pipe B are double-walled pipes. The first connector 1 is fixedly mounted on the connection end A1 of the first pipe A, and the second connector 2 is fixedly mounted on the connection end B1 of the second pipe B.

[0077] The process will be described firstly for the connection of the connecting fitting 3 to the first pipeline A.

[0078] In a first step El, an operator positions the first connecting end 31 of the connecting fitting 3 opposite the connecting end Al of the first pipeline A. More specifically, in this step El, the inner connecting conduit 33 is substantially aligned with the inner tube TLA of the first pipeline A and the outer connecting conduit 34 is substantially aligned with the first connector 1 mounted on the outer tube TE-A of the first pipeline A.

[0079] The operator then moves, in a second step E2, the connecting fitting 3 along the longitudinal axis X towards the connection end Al of the first pipe A. In this example, the outer conduit 34 is guided by the connector 1 to align it substantially with the outer tube TE-A of the first pipe A.

[0080] In a third step E3, the outer conduit 34 is manually fitted onto the first connector 1 so as to connect the outer conduit 34 with the outer tube TE-A of the first pipeline A. In this step, the inner conduit 33 is blindly connected with the inner tube TLA of the first pipeline A. In other words, the connecting fitting 3 allows each conduit 33, 34 to be connected simultaneously with the two inner tubes TLA and outer tube TE-A of the first pipeline A respectively. A seal J, preferably positioned between the inner conduit 33 and the inner tube TLA, ensures the seal of the connection.

[0081] In a preferred embodiment, the connection collar 35 of the fitting The connecting element 3 is pressed against the connection flange 13 of connector 1. These are secured by clipping with the locking element 5, thus preventing any disconnection of the connecting element 3 and the first pipe A. The operator then moves the safety element 6 onto the locking element 5 to prevent it from being unintentionally unlocked. In this example, the safety element 6 is also clipped to the locking element 5. It goes without saying that the locking and securing mechanisms could be implemented differently.

[0082] The whole set of steps is then repeated for the connection of the connecting fitting 3 to the second pipeline B. In the first step El of positioning the second connecting end 32 opposite the second pipeline B, the inner conduit 33 of the connecting fitting 3 is positioned opposite the inner tube TLB of the second pipeline B and the outer conduit 34 of the connecting fitting 3 is positioned opposite the second connector 2 mounted on the outer tube TE-B of the second pipeline B.

[0083] When the operator moves the connecting fitting 3 along the longitudinal axis X, the inner connecting conduit 33 is blindly inserted onto the inner tube TL B of the second pipeline B when connecting the outer connecting conduit 34 with the outer tube TE-B of the second pipeline B via the second connector 2. A seal J preferably positioned between the inner connecting conduit 33 and the inner tube TLB ensures the sealing of the connection.

[0084] When the connecting fitting 3 is a T-fitting comprising three connecting ends 31, 32, 37, for connecting three pipes A, B, C, the whole set of steps is repeated to connect the third pipe C. Alternatively, a T-fitting 3 may only allow the connection of two pipes A, B. In this case, a sealing device (not shown) is in this example put in place to plug the third connecting end 37 and prevent any risk of leakage.

Claims

Claims

1. Fluid circuit (CF), in particular for aircraft, comprising: • at least one first pipe (A) made of thermoplastic material comprising a connection end (Al) comprising a connector (1), hereinafter “first connector”, the first pipe (A) comprising at least one tube (TA), • at least one second pipe (B) made of thermoplastic material comprising a connection end (B1) comprising a connector (2), hereinafter “second connector”, the second pipe (B) comprising an outer tube (TE-B) and an inner tube (TI-B) mounted in the outer tube (TE-B), the first pipe (A) and the second pipe (B) extending along a longitudinal axis (X), and • a connecting connector (3) made of thermoplastic material, for sealingly connecting the two connection ends (Al, Bl), comprising: • at least one first connection end (31) configured to be mechanically connected to the first connector (1), • at least one second connection end (32) configured to be mechanically connected to the second connector (2), • an internal connecting conduit (33) configured to fluidically connect at least the tube (TA) of the first pipe (A) and the internal tube (TI-B) of the second pipe (B), an external connecting conduit (34) configured to cooperate with at least the external tube (TE-B) of the second pipe (B), the external connecting conduit (34) being in one piece, the inner connecting conduit (33) being trapped in the outer connecting conduit (34) so ​​as to prevent any separation of the inner connecting conduit (33) and the conduit external connecting conduit (34), the internal connecting conduit (33) being mounted at a determined position in the external connecting conduit (34) so ​​as to allow a connection of the internal connecting conduit (33) with at least the internal tube (TI-B) of the second pipe (B) in a blind manner when connecting the external connecting conduit (34) with at least the external tube (TE-B) of the second pipe (B).

2. Fluid circuit (CF) according to claim 1, comprising at least one spacer (8) mounted between the inner connecting conduit (33) and the outer connecting conduit (34), so as to connect them mechanically, the connecting connector (3) forming a single-piece assembly.

3. Fluid circuit (CF) according to one of claims 1 to 2, in which the connecting connector (3) is made of a thermoplastic material chosen from: polyetheretherketone and polyamides loaded with glass fibers.

4. Fluid circuit (CF) according to one of claims 1 to 3, wherein the tube (TA) of the first pipe (A) is an inner tube (TI-A), the first pipe (A) comprising an outer tube (TE-A), the inner tube (TI-A) being mounted in the outer tube (TE-A), the inner connecting conduit (33) of the connecting connector (3) is configured to fluidically connect the inner tube (TI-A) of the first pipe (A) and the inner tube (TI-B) of the second pipe (B), and the outer connecting conduit (34) is configured to connect the outer tube (TE-A) of the first pipe (A) and the outer tube (TE-B) of the second pipe (B).

5. Fluid circuit (CF) according to one of claims 1 to 4, comprising a third pipe (C) made of thermoplastic material extending along a lateral axis (Y) orthogonal to the longitudinal axis (X), the third pipe (C) comprising at least one tube (TC), the third pipe (C) comprising a connection end (Cl) comprising a connector (7), hereinafter "third connector", the connecting fitting (3) comprises a third connection end (37) configured to be mechanically connected to the third connector (7), the internal connecting conduit (33) being configured to fluidically connect the tube (TA) of the first pipe (A), the tube

6.

7.

8. interior (TI-B) of the second pipe (B) and the tube (TC) of the third pipe (C). Fluid circuit according to claim 5, in which the inner connecting conduit (33) and the outer connecting conduit (34) have a "T" shape in which the inner connecting conduit (33) is trapped in the outer connecting conduit (34). Aircraft comprising at least one fluid circuit according to one of claims 1 to 6. Method for connecting at least a first pipe (A) and a connecting fitting (3) made of thermoplastic material of a fluid circuit (CF) according to one of claims 1 to 6, the method comprising at least the steps consisting of: connecting the outer connecting conduit (34) of the connecting fitting (3) with at least the outer tube (TE-B) of the second pipe (B), and simultaneously, blindly connecting the inner connecting conduit (33) with at least the inner tube (TI-B) of the second pipe (B).

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