Pipe for conveying a fluid, fluid circuit and associated process

Abstract

A fluid conduit (1) for conveying a fluid at a pressure greater than or equal to 0.4 MPa, particularly for an aeronautical application, the fluid conduit (1) comprising a thermoplastic body (2) having at least two main fluid communication openings (20), the thermoplastic body (2) having an inner fluid guidance surface (2i) and an outer surface (2e) opposite the inner surface (2i), and a coating (3) completely covering the outer surface (2e) of the thermoplastic body (2), the coating (3) being formed from a plurality of resin-impregnated reinforcing fiber layers (4), the reinforcing fiber layers (4) having been positioned on the thermoplastic body (2) and bonded to said thermoplastic body (2). Abstract figure: Figure 2

Description

Title of the invention: Pipe for carrying a fluid, associated fluid circuit and method Technical field

[0001] The present invention relates to the field of producing a fluid circuit, in particular, for supplying a plurality of equipment with a high-pressure fluid, for example, fuel cells.

[0002] In order to generate significant electrical power, it has been proposed to use a plurality of fuel cells in parallel. For this purpose, it is necessary to provide a fluid collector comprising an air inlet connected to an air compressor and a plurality of air outlets connected to the fuel cells in order to supply them. The fluid collector must have significant mechanical strength to provide each air outlet with a high-pressure air flow. The fluid collector must withstand a maximum internal pressure of at least 0.4 Mpa, preferably 0.43 Mpa (4.3 bar).

[0003] In a known manner, to withstand significant mechanical forces, the fluid collector is made of metal. The metal collector traditionally comprises a metal body comprising fluid openings equipped with fixing plates in order to practically connect the fluid collector to an air compressor or a fuel cell. Such a metal part is heavy, complex and expensive to produce since it is necessary to first manufacture a specific mold to obtain the desired fluid collector. In a research and development phase, the definition of a fluid collector can evolve quickly and it is desirable to produce numerous prototypes, which is not possible when the fluid collector must be made of metal.

[0004] In order to eliminate this drawback, it has been proposed to produce a fluid collector by 3D printing in plastic material, but this does not have sufficient pressure resistance. One solution would be to increase the thickness of the plastic material, but this is not possible with traditional manufacturing equipment. Manufacturing by 3D printing in metal material is also not suitable. Such a manufacturing process does not allow the production of large parts and is expensive.

[0005] The invention thus aims to eliminate at least some of these drawbacks by providing a high-pressure fluid pipeline that can be manufactured in a practical manner with great freedom of design during a prototyping phase. Although the invention was originally born to manufacture a fluid collector for supplying fuel cells with a high pressure air flow, the invention aims to manufacture a pipeline for the circulation of any high pressure fluid. PRESENTATION OF THE INVENTION

[0006] The invention relates to a fluid pipe for conducting a fluid at a pressure greater than or equal to 0.4 MPa, in particular for an aeronautical application, the fluid pipe comprising: • A thermoplastic body comprising at least two main fluid communication openings, the thermoplastic body having an inner fluid guiding surface and an outer surface opposite the inner surface, and • A coating completely covering the outer surface of the thermoplastic body, the coating being formed from a plurality of layers of reinforcing fibers impregnated with resin, the reinforcing fiber layers having been positioned on the thermoplastic body and consolidated on said thermoplastic body.

[0007] Advantageously, the thermoplastic body is produced quickly from thermoplastic material. The coating makes it possible to reinforce, in the manner of armor, the thermoplastic body in order to give the fluid pipe high mechanical resistance. Advantageously, the coating is consolidated directly onto the thermoplastic body, which makes it possible to produce a custom coating.

[0008] According to one aspect, the thermoplastic body comprises at least one auxiliary opening configured to receive at least one probe for measuring a parameter of the fluid circulating in the fluid pipe. This advantageously makes it possible to provide, from the design of the thermoplastic body, the location of the auxiliary opening.

[0009] According to one aspect, the thermoplastic body is produced by 3D printing so as to offer high design freedom, which is ideal during a prototyping phase.

[0010] According to one aspect, the thermoplastic body is made of an amorphous thermoplastic polyetherimide material. Such a material offers high mechanical strength and is not thermally affected by the consolidation phase of the coating. Preferably, the material of the thermoplastic body has a melting temperature greater than 120°C, preferably greater than 150°C, preferably greater than 180°C.

[0011] According to one aspect, a connecting tube is mounted in each main opening. This makes it easier to mount the interface at each main opening. According to one aspect, the connecting tube is made of carbon. According to one aspect, a fixing plate is secured to the connecting tube.

[0012] According to one aspect, the connecting tube is secured to the thermoplastic body by gluing, which allows practical and rapid implementation.

[0013] According to one aspect, the connecting tube being mounted in the thermoplastic body according to an interface zone, the coating covers the interface zone. The interface zone is advantageously reinforced, which limits the occurrence of mechanical weakness. According to one aspect, the coating covers the connecting tube over a length greater than 2 cm.

[0014] The invention also relates to a fluid circuit comprising a plurality of fluid pipes, as presented previously, which are connected together.

[0015] The invention also relates to a method of manufacturing a fluid pipe for conducting a fluid at a pressure greater than or equal to 0.4 MPa, in particular for an aeronautical application, the method comprising steps consisting of: • Produce a thermoplastic body comprising at least two main fluid communication openings, the thermoplastic body comprising an inner fluid guiding surface and an outer surface opposite the inner surface, • Completely covering the outer surface of the thermoplastic body with an unconsolidated coating comprising a plurality of layers of reinforcing fibers impregnated with unconsolidated resin, and • Consolidate the resin to stiffen the coating on the thermoplastic body.

[0016] According to one aspect, the method comprises a step of securing a connecting tube to each main opening of the thermoplastic body according to an interface zone.

[0017] According to one aspect, the method comprises a step of completely covering the outer surface of the thermoplastic body and the interface area with the coating. PRESENTATION OF THE FIGURES

[0018] The invention will be better understood on reading the description which follows, 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.

[0019] [Fig.l] is a schematic representation of a fluid circuit connecting an air compressor to a plurality of fuel cells to power them.

[0020] [Fig.2] is a schematic representation of a fluid pipeline according to a embodiment of the invention.

[0021] [Fig.3] is a schematic representation of a thermoplastic body of a ca- fluid finalization.

[0022] [Fig.4] is a schematic representation of the thermoplastic body with connecting tubes secured at its main openings.

[0023] [Fig.5] is a schematic representation of the thermoplastic body of [Fig.4] covered with an unconsolidated coating.

[0024] [Fig. 6] is a schematic representation of the covering of an interface zone between the thermoplastic body and a connecting tube with the unconsolidated coating.

[0025] [Fig.7] is a schematic representation of the consolidation of the pipeline of unconsolidated fluid.

[0026] [Fig.8] is a schematic representation of the fluid pipeline after consolidation.

[0027] [Fig.9] is a schematic representation of the joining of a plate of attachment to a fluid line connecting tube.

[0028] It should be noted that the figures set out the invention in detail for implementing the invention, said figures of course being able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0029] The invention will be presented with reference to [Fig. 1] for an electrical generation system for an aircraft comprising a plurality of fuel cells P1-P4 and a fluid manifold configured to supply the fuel cells P1-P4 with a high-pressure air flow from an air compressor COMP. As illustrated in [Fig.l], the fluid manifold (fluid circuit) comprises a plurality of fluid lines 1 which are connected together in order to fluidically connect a fluid inlet, mounted on the air compressor COMP, to a plurality of fluid outlets mounted on the fuel cells P1-P4. It goes without saying that the fluid circuit could comprise a different number of fluid inlets / outlets.

[0030] The invention applies to any fluid circuit comprising at least one fluid pipe 1 configured to conduct a fluid at a pressure greater than 0.2 MPa. In practice, each fluid pipe 1 must withstand a maximum internal pressure at least equal to 0.4 Mpa (4 bar), preferably 0.43 Mpa (4.3 bar). Subsequently, the fluid is an air flow but it goes without saying that any other gaseous or liquid fluid could be suitable.

[0031] With reference to [Fig. 2] showing a ready-to-use fluid pipe 1, each fluid pipe 1 comprises a thermoplastic body 2 comprising at least two main fluid communication openings 20. In this example, the fluid pipe 1 has a T or Y shape and comprises three openings main openings 20, namely, one inlet and two outlets. As will be presented later, the fluid pipe 1 comprises connecting tubes 4 secured to the main openings 20 of the thermoplastic body 2 and a coating 3 covering the thermoplastic body 2. In this example, a fixing plate 5 is further secured to each connecting tube 4.

[0032] With reference to [Fig. 3] showing the thermoplastic body 2 alone, the thermoplastic body 2 comprises an inner surface 2i for guiding the fluid and an outer surface 2e opposite the inner surface 2i (see also [Fig. 6]). According to a preferred aspect, the thermoplastic body 2 is produced by 3D printing. This is particularly suitable for rapid prototyping, 3D printing combining freedom of design and speed of manufacturing. In this example, the thermoplastic body 2 has a T or Y shape defining several branches whose section, length and orientation can be determined according to the wishes of the designer.

[0033] Advantageously, with reference to [Fig. 2], the thermoplastic body 2 comprises at least one auxiliary opening 21 configured to receive at least one probe for measuring a parameter of the fluid circulating in the fluid pipe 1. For example, auxiliary openings 21 may be formed to receive a temperature, pressure, humidity, etc. probe. Manufacturing by 3D printing offers great freedom for the positioning of the auxiliary openings 21 and, consequently, for the positioning of the probes. This makes it possible, during a prototyping phase, to obtain a measurement of a fluid parameter at a precise location in the fluid pipe 1.

[0034] In this example, with reference to [Fig. 3], the thermoplastic body 2 comprises two auxiliary openings 21 so as to receive two probes. By way of illustration, [Fig. 1] shows the mounting of two probes S1, S2 in the fluid pipe 1 which are connected to a computer CAL in order to know the parameters of the fluid circulating in the fluid pipe 1.

[0035] According to one aspect, the thermoplastic body 2 is made of a plastic material comprising an amorphous thermoplastic polyetherimide also called PEI. Such a plastic material allows, on the one hand, 3D printing with traditional equipment and, on the other hand, a thermal resistance preventing any deformation below a temperature of 120°C or below 180°C depending on the material used as will be presented later. Advantageously, such thermal resistance makes it possible to consolidate a thermoplastic resin without risk of mechanical deformation.

[0036] Preferably, the thermoplastic body 2 is made of ULTEM®, in particular, of ULTEM® 9085 having a melting temperature greater than 120°C (preferably greater than 150°C, in particular, equal to 153°C) or of ULTEM 1010® having a melting temperature greater than 180°C (preferably greater than 210°C, in particular, equal to 216°C). Preferably, the thermoplastic body 2 is produced by 3D printing with thermoplastic wire having a diameter of the order of 0.3mm. Preferably, the thermoplastic body 2 is formed by circular printing of a first thickness called “skin”, of a second thickness called “filling” or “mesh” which is more aerated and of a third thickness called “skin”. Preferably, the thermoplastic body 2 has a thickness of between 0.9mm and 10mm.

[0037] In this example, with reference to [Fig. 4], the fluid pipe 1 comprises a connecting tube 4 mounted in each main opening 20 so as to allow the assembly of a fluid pipe 1 to another fluid pipe 1 or to a piece of equipment, for example, an air compressor COMP or a fuel cell P1-P4. The use of an interface makes it possible to achieve a traditional connection with a piece of equipment without requiring modification of the equipment's own interface. This is advantageous in a rapid prototyping context.

[0038] As shown in [Fig.2], in order to allow a traditional connection, a fixing plate 5 is secured to the connecting tube 4. Preferably, the fixing plate 5 is made of metal.

[0039] In this example, each connecting tube 4 is made of carbon in order to combine mechanical strength and reduced mass. According to one aspect, the connecting tube 4 is secured to the thermoplastic body 2 by gluing. Such a connection is rapid and robust.

[0040] As illustrated in [Fig.4], the connecting tube 4 is mounted in the thermoplastic body 2 according to an interface zone ZI. As illustrated in [Fig.6], the connecting tube 4 has an inner surface 4i for guiding the fluid and an outer surface 4e opposite the inner surface 4L. The connecting tube 4 is fitted into the thermoplastic body 2.

[0041] With reference to [Fig. 5], the unconsolidated fluid conduit 1' comprises an unconsolidated coating 3' completely covering the outer surface 2e of the thermoplastic body 2. The unconsolidated coating 3' is formed from a plurality of layers of resin-impregnated reinforcing fibers. The layers of reinforcing fibers are flexible and positioned on the thermoplastic body 2 so as to conform to the shape of the thermoplastic body 2.

[0042] In this example, the reinforcing fiber layers comprise carbon, glass, or similar reinforcing fibers. In this example, the resin is thermosetting, for example, of the epoxy type.

[0043] As illustrated in Figures 5 and 6, the unconsolidated coating 3' covers the interface zone ZI defined between the connecting tube 4 and the thermoplastic body 2. Such a covering makes it possible to improve the mechanical resistance at the level of the zone interface ZI when a high-pressure fluid passes. Preferably, the unconsolidated coating 3' covers the connecting tube 4 over a length L3 greater than 2 cm. In order to allow optimal adhesion of the layers of reinforcing fibers, glue is deposited between the connecting tube 4 and the layers of reinforcing fibers of the unconsolidated coating 3' over the length L3.

[0044] As illustrated in [Fig.7], the unconsolidated coating 3' is consolidated on said thermoplastic body 2, i.e., heated and compressed. In this example, the unconsolidated fluid pipe 1' is placed in an enclosure 7, for example a plastic envelope, in which heating and vacuum are applied in order to consolidate the resin-impregnated reinforcing fiber layers of the unconsolidated coating 3'. An autoclave consolidation method is, for example, suitable. Advantageously, the consolidation is carried out at a consolidation temperature which is lower than the melting temperature of the thermoplastic body 2. Preferably, the consolidation temperature of the resin is between 90°C and 120°C. Thus, a thermoplastic body 2 having a thermal melting temperature preventing any deformation below a temperature of 120°C or below 180°C allows optimal consolidation to be achieved.

[0045] After consolidation, with reference to [Fig. 8], a fluid pipe 1 (consolidated) is obtained comprising a coating 3 (consolidated) making it possible to form an armor on the thermoplastic body 2 which increases its mechanical resistance in order to obtain a mechanical resistance similar to that of a metal part. Advantageously, the thermoplastic body 2 fulfills a support function for the layers of reinforcing fibers during their consolidation, which makes it possible to form a “tailor-made” coating 3 on the thermoplastic body 2. Before consolidation, the layers of reinforcing fibers are malleable and can take the shape of the thermoplastic body 2. This is all the more advantageous since the thermoplastic body 2 can be freely designed, in particular, by 3D printing.

[0046] Preferably, the coating 3 has a thickness of between 1.5 mm and 2 mm. According to one aspect, the coating 3 has a thickness formed by 5 to 7 plies. Such a coating 3 makes it possible to form a fluid pipe 1 configured to withstand an internal pressure at least equal to 0.4 Mpa, preferably 0.43 Mpa.

[0047] With reference to [Fig. 9], a fixing plate 5 is then secured to each free end of the connecting tube 4, in particular, by securing members 6 such as bolts. Preferably, the securing members 6 of the fixing plate are coated with a sealing mastic in order to ensure a high degree of sealing and to limit corrosion. Preferably, the junction zone between the fixing plate 5 and the connecting tube 4 is also coated with a sealing mastic. Optionally, a corrosion limiting element galvanic can also be used, for example, glass fabric.

[0048] In practice, the auxiliary openings 21 formed in the thermoplastic body 2 are covered by the coating 3. After polymerization of the coating 3, an operator locally removes the coating 3 at the auxiliary openings 21 to uncover them and allow the mounting of probes. Preferably, the coating 3 is machined to uncover the auxiliary openings 21.

[0049] Thanks to the manufacturing method according to the invention, a fluid pipe 1 having the desired shape and mechanical strength is advantageously obtained in a reduced time. As illustrated in [Fig.l], several fluid pipes 1 can be combined together in a practical manner to form a fluid collector. The use of fixing plates 5 allows practical assembly to the air collector COMP and to the fuel cells P1-P4. The presence of auxiliary openings 21, formed directly in the thermoplastic body 2, makes it possible to avoid carrying out machining operations which could degrade the mechanical strength. It is thus possible to practically measure the properties of the fluid circulating in the fluid pipe 1. A new prototype of a pipe can be produced quickly to modify the shape of the fluid pipe but also the number and position of the auxiliary openings 21.

[0050] When in use, each fluid pipe 1 can guide a flow of hot air having a temperature of the order of 90°C and a maximum pressure of between 0.2 MPa and 0.43 MPA (between 2 and 4.3 bar). Each fluid pipe 1 must withstand a maximum internal pressure of at least 0.43 MPa (4.3 bar).

[0051] The fluid pipe 1 is optimized and has a high level of sealing for a reduced footprint. During prototyping, a new fluid pipe 1 can be produced quickly, which allows rapid feedback to be obtained.

Claims

Claims

1. Fluid pipe (1) for conducting a fluid at a pressure greater than or equal to 0.4 MPa, in particular for an aeronautical application, the fluid pipe (1) comprising: • A thermoplastic body (2) comprising at least two or more main fluid communication openings (20), the thermoplastic body (2) comprising an inner surface (2i) for guiding the fluid and an outer surface (2e) opposite the inner surface (2i), • a connecting tube (4) mounted in each main opening (20), the connecting tube (4) being secured in the thermoplastic body (2) according to an interface zone (ZI), and • A coating (3) entirely covering the outer surface (2e) of the thermoplastic body (2) and the interface zone (ZI), the coating (3) being formed from a plurality of layers of reinforcing fibers (4) impregnated with resin,the reinforcing fiber layers (4) having been positioned on the thermoplastic body (2) and consolidated on said thermoplastic body (2).,

2. Pipe (1) according to claim 1, wherein the thermoplastic body (2) comprises at least one auxiliary opening (21) configured to receive at least one measuring probe (SI, S2) of a parameter of the fluid circulating in the fluid pipe (1).

3. Pipe (1) according to one of claims 1 to 2, in which the thermoplastic body (2) is produced by 3D printing.

4. Pipe (1) according to one of claims 1 to 3, in which the thermoplastic body (2) is made of an amorphous thermoplastic polyetherimide material.

5. Pipeline (1) according to claim 1, wherein the connecting tube (4) is made of carbon.

6. Pipe (1) according to one of claims 1 to 5, in which the connecting tube (4) is secured to the thermoplastic body (2) by gluing.

7. Pipe (1) according to claim 6, in which the coating (3) covers the connecting tube (4) over a length (L3) greater than 2 cm.

8. Pipe (1) according to one of claims 1 to 7, in which a fixing plate (5) is secured to the connecting tube (4).

9. A fluid circuit comprising a plurality of fluid pipes (1) according to one of claims 1 to 8 which are connected together.

10. A method of manufacturing a fluid pipe (1) for conducting a fluid at a pressure greater than or equal to 0.4 MPa, in particular for an aeronautical application, the method comprising steps consisting of: • Producing a thermoplastic body (2) comprising at least two main fluid communication openings (20), the thermoplastic body (2) comprising an inner surface (2i) for guiding the fluid and an outer surface (2e) opposite the inner surface (2i), • Entirely covering the outer surface (2e) of the thermoplastic body (2) with an unconsolidated coating (3') comprising a plurality of layers of reinforcing fibers impregnated with unconsolidated resin, and • Consolidating the resin in order to stiffen the coating (3) on the thermoplastic body (2).

11. Method according to claim 10, comprising a step of securing a connecting tube (4) to each main opening (20) of the thermoplastic body (2) according to an interface zone (ZI).

12. A method according to claim 11, comprising a step of completely covering the outer surface (2e) of the thermoplastic body (2) and the interface zone (ZI) with the coating (3).

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