Multi-layer tube for air conditioning system of motor vehicle

Abstract

A tube (10) for an air conditioning system of a motor vehicle; the tube comprises: an inner tube (12) located in a radially inner position and configured to carry a fluid to be delivered wherein the inner tube (12) is made of one of the following materials: PA6 / 66, PA66, PA6T / 66, PA6T / 6 or EX1; an outer tube (14) located in a radially outer position, in which the outer tube (14) is made of a polyamide, the ratio of the number of methylene CH2 to the number of amide CONH in macromolecular repeating units of which is greater than or equal to 8; wherein EX1 is a reactive thermoplastic composition comprising a continuous phase of at least one thermoplastic polymer, and a discontinuous phase based on at least one reactive reinforcing chemical dispersed in said continuous phase.

Description

Technical Field

[0001] This invention relates to multi-layer pipes for use in motor vehicle air conditioning systems. The pipes are configured to transport fluid circulating within the air conditioning system. Background Technology

[0002] In the automotive industry, the pipes currently used in air conditioning systems are made of aluminum, possibly with rubber hoses. This solution ensures product functionality, but it has several drawbacks due to its heavy weight, poor vibration damping, generally high cost, and the risk of permanent deformation. Furthermore, the connection between the pipe ends and fittings must be achieved through brazing or cold forming, processes that require significant energy.

[0003] US2023 / 055055A1 discloses a hose for conveying refrigerant, comprising an inner layer, a reinforcing layer, and an outer layer. Each of the inner and outer layers comprises a thermoplastic resin composition having an island-like structure, the island-like structure comprising a matrix containing a thermoplastic resin and a structural domain containing an elastomer. The thermoplastic resin composition of the outer layer has a water vapor permeability coefficient of 10.0 g·mm / (m²·24h) or less than 10.0 g·mm / (m²·24h) at 60°C and 100% relative humidity. The thermoplastic resin composition of the inner layer has an oxygen permeability coefficient of 0.05 cm³·mm / (m²·day·mmHg) or less than 0.05 cm³·mm / (m²·day·mmHg) at 21°C and 50% relative humidity. The water vapor permeability of the hose is 6.0 mg / (240h·cm²) or less than 6.0 mg / (240h·cm²). The hydrofluoroolefin HFO-1234yf permeation rate of the hose is 170 g / (m²·72h) or less, and the mass of the outer surface of the hose per 1m² is 3000 g / m² or less. Summary of the Invention

[0004] One object of the present invention is to provide a pipe that can overcome the shortcomings of the prior art.

[0005] According to the present invention, this objective is achieved by a tube having the technical features listed in the appended independent claims.

[0006] In particular, these technical features give the tube improved mechanical strength and allow it to maintain its insulation properties even after bending.

[0007] Another advantage is that the tube can be manufactured easily, quickly, and economically, while ensuring good thermal insulation performance.

[0008] It should be understood that the appended claims are an integral part of the technical teachings provided in the following detailed description of the invention. In particular, the appended dependent claims define some preferred embodiments of the invention, which include some optional technical features.

[0009] Further features and advantages of the invention will become apparent from the following detailed description, which is provided herein as a non-limiting example only, and in particular with reference to the accompanying drawings summarized below. Attached Figure Description

[0010] Figure 1 This is a perspective view of a tube manufactured according to an exemplary embodiment of the present invention.

[0011] Figure 2 This is a perspective view of a tube manufactured according to another exemplary embodiment of the present invention. Detailed Implementation

[0012] Referring to the accompanying drawings, reference numeral 10 generally indicates a pipe for a motor vehicle air conditioning system; the pipe 10 includes:

[0013] - Inner tube 12, located radially inward and configured to carry the fluid to be transported, wherein the inner tube 12 is made of one of the following materials, particularly one of the following materials: PA6 / 66, PA66, PA6T / 66, PA6T / 6, or "EX1" (which will be defined below),

[0014] - Outer tube 14, located in a radially outer position, wherein the outer tube 14 is based on polyamide, particularly made of polyamide, wherein the ratio of the number of methylene CH2 to the number of amide groups CONH in the macromolecular repeating unit of the polyamide is greater than or equal to 8.

[0015] For example, pipe 10 can be used in motor vehicles, such as automobiles. In particular, pipe 10 can be used in the air conditioning systems of motor vehicles, especially for high-pressure liquid lines.

[0016] The inner tube 12 is configured to carry a fluid to be transported, particularly a refrigerant fluid, such as a liquid or gaseous refrigerant. The refrigerant fluid that can flow in the inner tube 12 may be known in itself. The inner tube 12 has low permeability to gases used in air conditioning circuits (e.g., R-1234YF, R134a, R290, or R744), thus limiting their diffusion to the external environment. The material used to make the inner tube 12, PA6 / 66, PA66, PA6T / 66, or PA6T / 6, is a specific type of polyamide.

[0017] Preferably, the inner tube 12 is based on PA6 / 66, and in particular made of PA6 / 66. This material provides a particularly satisfactory level of impermeability to gases used in air conditioning circuits.

[0018] According to some preferred variations of the invention, the inner tube 12 is based on the material defined in any one of claims 11-16 of patent EP2415824B1, or the material defined in any one of claims 13-24 of patent FR2963624B1, particularly made of the aforementioned materials. For example, the inner tube 12 is based on a material obtained from one or more methods described and / or claimed in patent EP2415824B1 or patent FR2963624B1, particularly made of the aforementioned materials. The contents of EP2415824B1 or FR2963624B1 are incorporated herein by reference and will not be repeated herein for the sake of brevity.

[0019] Specifically, the inner tube 12 is based on, and in particular made of, the following material, which for the sake of brevity will be referred to as "EX1":

[0020] A reactive thermoplastic composition comprising a continuous phase based on at least one thermoplastic polymer and a discontinuous phase dispersed in said continuous phase of at least one reactive reinforcing chemical, wherein said reactive reinforcing chemical is incompatible with said at least one thermoplastic polymer, and wherein said reinforcing chemical is selected from epoxy resins, polyorganosiloxanes having SiH functional groups, diisocyanates, polyisocyanates, and mixtures thereof; such thermoplastic compositions do not contain any compatibilizer between the continuous and discontinuous phases and comprise products of in-situ grafting, branching, and / or crosslinking reactions, wherein said products are obtained by reacting at a concentration greater than 10... 2 s -1 And preferably greater than or equal to 10 3 s -1 The reaction is achieved by reactively mixing the continuous and discontinuous phases at a shear rate; the in-situ reaction products between the reactive enhancer and the polymer chains of the at least one thermoplastic polymer result in the polymer chains of the at least one thermoplastic polymer having a grafted, branched, or cross-linked structure, and the discontinuous phase is uniformly dispersed in the continuous phase. Preferably, the discontinuous phase is in the form of nodules with an average particle size of less than 5 μm. Preferably, the average particle size is 2 μm to 5 μm, with a maximum standard deviation of 0.5 μm.

[0021] More specifically, the inner tube 12 is made of the following material, which for simplicity will be referred to as "EX2":

[0022] The “EX1” material, wherein the at least one thermoplastic polymer is selected from homopolymers and copolymers of olefins, aliphatic polyamides of the phthalamide class, semi-aromatic polyamides of the phthalamide class and aromatic polyamides of the phthalamide class, polyimide (PI), polyamide-imide (PAI), polyetherimide (PEI), thermoplastic elastomer (TPE), polyphenylene sulfone, polyether sulfone (PES), polystyrene (PS), polysulfone (PSU), polyester, polyethylene oxide and other olefin-based monomers, polyether ether ketone (PEEK), polyether ketone (PEK), polyether ketone ketone (PEKK), block copolymers thereof and mixtures thereof. Preferably, the at least one thermoplastic polymer is selected from polypropylene, propylene-ethylene copolymer, propylene-hexene copolymer, ethylene-butene copolymer and ethylene-octene copolymer, polyethylene, copolyester (COPE), polyether block amide (PEBA), thermoplastic polyurethane, polyamide 6, polyamide 4.6, polyamide 6.6, polyamide 6.6.6, polyamide 11, polyamide 12, their block copolymers and mixtures thereof.

[0023] More specifically, the inner tube 12 may be made of the following material, which for simplicity will be referred to as "EX3":

[0024] The “EX2” material, wherein the discontinuous phase is based on at least one epoxy resin, and preferably on an amide crosslinking system with or without acrylated amide blockers or methacrylated amide blockers. The continuous phase, particularly the at least one thermoplastic polymer, is selected from aliphatic polyamides of the phthalamide class, semi-aromatic polyamides of the phthalamide class, and aromatic polyamides of the phthalamide class. Preferably, the at least one thermoplastic polymer is selected from polyamide 6, polyamide 4.6, polyamide 6.6, polyamide 6.6.6, polyamide 11, polyamide 12, their block copolymers, and mixtures thereof.

[0025] Material EX3 is a specific instance of the more general material EX2. Material EX2 is a specific instance of the more general material EX1. Therefore, material EX3 is a specific instance of the more general material EX1. Therefore, the inner tube 12 can be made of PA6 / 66, PA66, PA6T / 66, PA6T / 6, EX1, EX2 or EX3.

[0026] These materials, such as EX1, EX2, or EX3, exhibit particularly satisfactory resistance to permeation by gases used in air conditioning circuits.

[0027] According to some possible implementations, EX1, EX2, or EX3 contains PA6 and PA66. Therefore, in these cases, the inner tube 12 is made of EX1 containing PA6 and PA66, or EX2 containing PA6 and PA66, or EX3 containing PA6 and PA66. This material ensures high resistance to permeation by gases used in the air conditioning circuit.

[0028] Advantageously, when the ratio of CH2 groups to CONH groups in the repeating units of the polymer is greater than or equal to 8, it exhibits good resistance to zinc chloride (ZnCl2). Preferably, the ratio of CH2 groups to CONH groups is greater than 8. In fact, the outer tube 14 may come into contact with zinc chloride during operation; zinc chloride is a molecule formed by the interaction of salt deposited on roads for snow melting purposes with the metal parts of automobiles. Furthermore, the outer tube 14 has low permeability to moisture (especially water vapor). In fact, any moisture entering the tube 10 can damage the compressor of the air conditioning system.

[0029] According to some preferred embodiments, the outer tube 14 is based on one of the following materials, particularly PA610, PA612, PA12, PA11, PA1012, or PA10T. These materials are specific types of polyamides that exhibit very good resistance to zinc chloride.

[0030] refer to Figure 2 In a variation, pipe 10 includes at least one intermediate pipe 16, which is radially inserted between inner pipe 12 and outer pipe 14. In the example shown, there is only one intermediate pipe 16. Specifically, the intermediate pipe 16 is in contact with both outer pipe 14 and inner pipe 12. According to some possible variations, there are multiple intermediate pipes 16 between inner pipe 12 and outer pipe 14. The at least one intermediate pipe 16 can be used to improve the mechanical properties, thermal insulation properties, or gas impermeability of pipe 10.

[0031] The intermediate tube 16 is preferably made of a polymeric material, such as EVOH (ethylene-vinyl alcohol copolymer). Preferably, the intermediate tube 16 is made of a material with low gas permeability, such as EVOH. According to some possible variations, the intermediate tube 16 is made of a material (preferably a polymeric material) that can improve the adhesion between the outer tube 14 and the inner tube 12.

[0032] In this example, tube 10 has a circular cross-section. In particular, tubes 12, 14, and any intermediate tube 16 also have circular cross-sections.

[0033] In particular, tubes 12, 14, and any intermediate tubes 16 are smooth, especially on their exterior and interior.

[0034] Preferably, there are no other elements, tubes, or layers in the radial interior of the inner tube 12.

[0035] exist Figure 1 In this example, the thickness of the inner tube 12 is greater than the thickness of the outer tube 14; specifically, the thickness of the inner tube 12 is at least twice the thickness of the outer tube 14. Figure 2 In the example, the thickness of the inner tube 12 is greater than the thickness of the outer tube 14. In particular, the thickness of the inner tube 12 is at least twice the thickness of the outer tube 14, and the thickness of the inner tube 12 is greater than the thickness of the intermediate tube 16. In particular, the thickness of the inner tube 12 is at least twice the thickness of the intermediate tube 16.

[0036] Specifically, there are no gaps between tubes 12, 14 and optional tube 16 of tube 10.

[0037] In the preferred embodiments shown and described herein, all tubes 12, 14, and optionally 16 of tube 10 are made of polymer material. Advantageously, the plurality of tubes 10 can therefore be welded to each other, and such welding is an economical process requiring very little energy.

[0038] Preferably, the tube 10 is configured to withstand an internal fluid pressure of at least 150 bar at room temperature (20°C to 25°C) and at least 62 bar at 125°C.

[0039] The pipe 10 of the present invention can be applied to the fields of automobiles, aircraft, heavy trucks and ships, and can be used in fluid transfer applications using pumps or compressors, or generally in any system using pressurized fluids such as internal combustion engines, hybrid engines or electric motors.

[0040] For example, tube 10 is manufactured by simultaneously extruding inner tube 12 and outer tube 14, as well as intermediate tube 16, if present.

[0041] The present invention also relates to a system for conveying fluids, comprising:

[0042] - According to any variant of tube 10; and

[0043] - A fluid source configured to supply the fluid to be transported and fluidly connected to the inner tube 12 of the tube 10.

[0044] The present invention also relates to an air conditioning system for a motor vehicle, comprising a pipe 10 according to any variation.

[0045] The present invention also relates to motor vehicles including the aforementioned air conditioning system.

[0046] The invention also relates to a method for manufacturing a tube 10 according to any embodiment thereof, comprising the step of simultaneously extruding an inner tube 12 and an outer tube 14. For the sake of brevity, the characteristics of tubes 12 and 14 will not be repeated. Optionally, the at least one intermediate tube 16 (if present) is extruded simultaneously with the inner tube 12 and the outer tube 14.

[0047] Of course, without departing from the principles of the invention, the form and details of the embodiments can be widely changed relative to the content described and illustrated herein as non-limiting examples, without departing from the scope of the invention as defined in the appended claims.

Claims

1. A pipe (10) for a motor vehicle air conditioning system, said pipe comprising: - An inner tube (12), located radially inward and configured to carry the fluid to be transported, wherein the inner tube (12) is made of one of the following materials: PA6 / 66, PA66, PA6T / 66, PA6T / 6, or EX1. - An outer tube (14) located in a radially outer position, wherein the outer tube (14) is made of polyamide, wherein the ratio of the number of methylene CH2 to the number of amide groups CONH in the macromolecular repeating unit of the polyamide is greater than or equal to 8; EX1 is the following material: A reactive thermoplastic composition comprising a continuous phase based on at least one thermoplastic polymer and a discontinuous phase dispersed in said continuous phase based on at least one reactive reinforcing chemical, wherein said reactive reinforcing chemical is incompatible with said at least one thermoplastic polymer, and wherein said reinforcing chemical is selected from epoxy resins, polyorganosiloxanes having SiH functional groups, diisocyanates or polyisocyanates, and mixtures thereof; wherein said thermoplastic composition does not contain any compatibilizer between said continuous phase and said discontinuous phase, and comprises products of in-situ grafting, branching and / or crosslinking reactions, wherein said products are obtained by reacting at a concentration greater than 10 2 s -1 The product of the in-situ reaction between the reactive enhancer and the polymer chains of the at least one thermoplastic polymer is obtained by reactively mixing the continuous phase and the discontinuous phase at a shear rate; the product of the in-situ reaction between the reactive enhancer and the polymer chains of the at least one thermoplastic polymer results in the polymer chains of the at least one thermoplastic polymer having a grafted, branched or cross-linked structure, and the discontinuous phase is uniformly dispersed in the continuous phase.

2. The tube according to claim 1, wherein the outer tube (14) is made of one of the following materials: PA610, PA612, PA12, PA11, PA1012 or PA10T.

3. The tube according to claim 1 or 2, wherein the inner tube (12) is made of PA6 / 66.

4. The tube according to claim 1 or 2, wherein the inner tube (12) is made of EX1.

5. The tube according to claim 4, wherein the inner tube (12) is made of a material referred to as EX2: The EX1 material, wherein the at least one thermoplastic polymer is selected from homopolymers and copolymers of olefins, aliphatic polyamides of the phthalamide class, semi-aromatic polyamides of the phthalamide class and aromatic polyamides of the phthalamide class, polyimide (PI), polyamide-imide (PAI), polyetherimide (PEI), thermoplastic elastomer (TPE), polyphenylene sulfone, polyethersulfone (PES), polystyrene (PS), polysulfone (PSU), polyester, polyethylene oxide and other olefin-based monomers, polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK), block copolymers thereof and mixtures thereof.

6. The tube according to any one of the preceding claims, comprising at least one intermediate tube (16) radially inserted between the inner tube (12) and the outer tube (14).

7. The tube according to claim 6, wherein the intermediate tube (16) is made of EVOH.

8. The tube according to any one of the preceding claims, wherein the thickness of the inner tube (12) is greater than the thickness of the outer tube (14).

9. The tube according to claim 5, wherein the inner tube (12) is made of a material referred to as EX3: The EX2 material, wherein the discontinuous phase is based on at least one epoxy resin, and preferably on an amide crosslinking system having or not having an acrylated amide blocker or a methacrylated amide blocker; wherein the continuous phase is selected from polyphthalamide aliphatic polyamides, polyphthalamide semi-aromatic polyamides and polyphthalamide aromatic polyamides.

10. An air conditioning system for a motor vehicle, comprising a pipe (10) according to any one of the preceding claims.

11. A motor vehicle comprising an air conditioning system according to claim 10.

12. A method for manufacturing a tube (10) according to any one of claims 1 to 9, comprising the step of simultaneously extruding both the inner tube (12) and the outer tube (14).

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