Heavy-duty multilayer pipe

Abstract

The invention relates to a multilayer pipe (10), characterized in that it comprises at least: a semi-rigid tubular inner wall (12) delimiting an internal space (11') of the pipe (10); a tubular reinforcement outer wall (16) surrounding the inner wall (12), the outer wall (16) being reinforced by reinforcing means (17); the multilayer pipe (10) comprising an intermediate layer (14) extending between the inner (12) and outer (16) walls and comprising at least one non-Newtonian material such as a non-Newtonian fluid or gel. Figure 1

Description

Title of the invention: Resistant multilayer pipe Technical field of the invention

[0001] The invention relates, in general, to the technical field of pipe-type conduits and finds applications in particular in hybrid or electric vehicles, but can be applied to other fields.

[0002] The invention relates more specifically to a multilayer pipe for extinguishing a fire that breaks out in a battery pack of a hybrid or electric vehicle. Prior art

[0003] Electric or hybrid traction or propulsion motor vehicles comprise a plurality of electrochemical cells connected in series or parallel and designed to power an electric motor (traction or propulsion). The electrochemical cells generate current by chemical reaction, for example a lithium-ion (or Li-ion) type reaction, such as NMC, LFP, LMFP or NCA cells, Ni-Mh type, Ni-Cd type or lead type.

[0004] Typically, electrochemical cells are grouped into one or more battery modules connected to a power network to supply the electric motor. The battery modules are housed in a casing, forming a battery pack, also often referred to as a "battery pack." This casing generally contains a mounting interface and connection terminals. The casing thus forms an enclosed internal space that is inserted into the vehicle. More precisely, the casing is installed on the vehicle floor.

[0005] Furthermore, it is also known to group the electrochemical cells directly within the battery pack casing, thus eliminating the need for battery modules, which can be bulky and do not contribute to the production of electrical current. This solution notably optimizes the volume occupied by the battery pack, reduces its overall mass and size, and simplifies its assembly. This configuration, particularly used for prismatic cells, is known by the English term "Cell-to-Pack" (or CTP).

[0006] Finally, according to another alternative, the electrochemical cells can be integrated directly into the vehicle structure and therefore do not need to be grouped beforehand in a closed casing. The battery pack is an integral part of the vehicle structure.

[0007] In particular, in a first configuration designated by the English expression "Cell-to-Chassis" (or CTC), the cells are inserted into the chassis of the vehicle, in spaces formed in the floor of the vehicle, which makes it possible to reduce the total mass of the battery pack.

[0008] In a second configuration designated by the English expression "Cell-to-Body" (CTB), the cells directly replace the vehicle floor and become a structural element of the chassis subjected to stress and connecting two areas of the chassis. The CTB configuration is particularly suitable for blade-shaped cells, known as "blade batteries".

[0009] The electrochemical reactions that take place in a battery pack during operation, regardless of its configuration (modular, PTC, CTC, or TBC), tend to cause the battery temperature to rise. Despite the presence of cooling systems that control and regulate the battery pack temperature, the latter can be subject to a phenomenon known as "thermal runaway."

[0010] Thermal runaway can originate from various sources, including: • a battery overload; • prolonged exposure of the battery to high temperatures; • a short circuit; • a sudden collision of the car against an obstacle which mechanically deforms the electrochemical cells; • intensive use of the vehicle's battery, for example when towing a heavy load or repeatedly accelerating the vehicle suddenly.

[0011] More specifically, during a thermal runaway phenomenon of the battery block, exothermic chain reactions are triggered in the battery modules, these reactions producing an uncontrolled accumulation of heat in the battery block.

[0012] Exothermic reactions can raise the temperature of electrochemical cells to around 1000°C or more and cause a fire in the battery pack, which can then spread rapidly throughout the vehicle. It is therefore important to prevent thermal runaway from occurring in the vehicle, or, if thermal runaway does occur, to extinguish the fire as quickly as possible.

[0013] To achieve this, it is known, in the prior art, to install in electric or hybrid vehicles a sealed pipe which connects an external access point of the car, by for example a fuel filler flap or a roll bar on a "pick-up" type vehicle, in the interior space of the battery pack housing.

[0014] Such a hose allows, in the event of a fire, the internal space of the casing to be filled with a fire-extinguishing fluid until the battery modules are completely submerged. The use of the hose thus reduces the response time to a fire.

[0015] However, the hoses proposed in the prior art are not designed to withstand shocks and deformations and do not resist shear, compression, torsion, or any average mechanical stress that might be applied in the event of an accident. Thus, in the event of a collision between the vehicle and an obstacle, the hose may be damaged, for example, cracked or even broken, which slows down or prevents the filling of the extinguishing fluid battery pack when the latter undergoes thermal runaway. The intervention time to stop the fire is therefore prolonged, which can worsen material and human damage.

[0016] In general, such sealed pipes can be used in all types of industrial sectors, particularly in the space, automotive, and aeronautical fields. The mechanical problems of resistance to shock and deformation mentioned above are applicable to these pipes and can be solved by the present invention. Description of the invention

[0017] The invention aims to remedy all or part of the drawbacks of the prior art by proposing in particular a multilayer pipe resistant to impacts.

[0018] In the context of the invention, "shock" means a collision of the multilayer pipe against an external body which causes deformations of the pipe, in particular compression and / or tension and / or shear stresses.

[0019] To this end, according to a first aspect of the invention, a multilayer pipe is proposed, remarkable in that it comprises at least: • a semi-rigid tubular internal wall delimiting an internal space of the pipe; • an external tubular reinforcement wall surrounding the internal wall, the external wall being reinforced by means of reinforcement; the multilayer pipe comprising an intermediate layer extending between the inner and outer walls and comprising at least one non-Newtonian material such as a non-Newtonian fluid or gel.

[0020] Such a multilayer pipe has the technical advantage of being more impact-resistant thanks to its multiple walls and layer, allowing it to perform its protective function durably over time. Thus, the multilayer pipe can be used to convey fluids from an inlet to an outlet, and this in many systems that may be subject to constraints, for example systems in the automotive, space or aeronautical sectors.

[0021] The inner wall of the pipe is semi-rigid to allow the pipe to have the necessary flexibility to adapt to a plurality of geometric arrangements, while maintaining a predetermined mechanical resistance.

[0022] Furthermore, the tubular reinforcement of the outer wall of the pipe strengthens the pipe, making it more resistant to compression, tension, and shear stresses. Preferably, the outer wall comprises or is made of one or more polymers, for example polyethylene, polyurethane, and / or one or more composite materials, for example carbon fibers, glass fibers, or Kevlar®.

[0023] Furthermore, due to the intrinsic characteristics of the fluid or a non-Newtonian gel, in particular shear-thickening, the viscosity of the fluid or gel increases when the force applied to it increases so that the intermediate layer of the pipe "solidifies" when the pipe undergoes a shock at a high speed, which makes it possible to offer the pipe additional resistance to stresses and to protect the internal wall of the pipe.

[0024] Thus, the combination of the internal and external walls with the intermediate layer allows the pipe to be more resistant, particularly in the event of a major shock, and thus to continue to fulfill its function.

[0025] According to one embodiment, the inner wall, the intermediate layer, and the outer wall are distinct from one another and bonded together by bonding agents. The bonding agents prevent the separation of the inner and outer walls of the intermediate layer when the pipe is subjected to impacts.

[0026] According to one embodiment, the multilayer pipe includes additional layers of material to enhance the mechanical properties of the pipe, the additional layers being included between the inner and outer walls of the pipe.

[0027] According to one embodiment, the non-Newtonian material consists of a shear-thickening non-Newtonian fluid and / or gel. Preferably, the non-Newtonian material consists solely of a non-Newtonian fluid, for example based on polyborodimethylsiloxane (PBDMS) or D3O®.

[0028] According to one embodiment, the pipe includes a protective layer surrounding the outer reinforcing wall. The protective layer is preferably an anti-corrosion layer, for example, an anti-corrosion paint that protects the pipe from the surrounding environment. In particular, the protective layer helps to extend the pipe's lifespan.

[0029] According to one embodiment, to allow the passage of fluid inside the pipe, the inner wall of the multilayer pipe is sealed. Additionally, the inner wall is made of rubber, preferably of a rubber compound. The rubber has high elastic resistance, enabling it to withstand the stresses experienced by the inner wall in the event of an impact. Practically, the inner wall 12 may comprise: • nitrile rubber; and / or • ethylene, propylene, diene, and monomer-based rubber (EPDM rubber); and / or • polypropylene; and / or • silicone.

[0030] According to one embodiment, the outer reinforcing wall is configured to resist shear. In particular, the reinforcement means for the outer reinforcing wall include a rigid mesh. Preferably, the rigid mesh comprises one or more high-tenacity materials that protect the pipe from shear stresses and cuts.

[0031] According to another aspect of the invention, it relates to a vehicle remarkable in that it comprises an exterior access, an interior space of the vehicle and a multilayer pipe as described above, the multilayer pipe being suitable for connecting the exterior access to the interior space of the vehicle.

[0032] The installation of such a multilayer hose in a vehicle allows the hose to be used even in an emergency situation, for example a vehicle accident.

[0033] According to one embodiment, the multilayer pipe allows a liquid to be injected into the interior space of the vehicle.

[0034] According to a particular embodiment, the vehicle is a hybrid or electric vehicle comprising a battery pack; the multilayer pipe allowing the injection of a fire extinguishing fluid into an interior space of the vehicle's battery pack to stop a thermal runaway of said battery pack, even when the pipe is subjected to a shock. Brief description of the figures

[0035] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate: • [Fig.1]: a cross-sectional view of a multilayer pipe according to a first embodiment of the invention; • [Fig.2]: a side view of the multilayer pipe from [Fig.1]; • [Fig.3]: a schematic view of a hybrid or electric vehicle comprising a multilayer pipe, according to a first embodiment of the invention; • [Fig.4]: a schematic view of the hybrid or electric vehicle including the multilayer pipe, according to a second embodiment of the invention; • [Fig.5]: a schematic view of the hybrid or electric vehicle including the multilayer pipe, according to a third embodiment of the invention.

[0036] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. Detailed description of an implementation method

[0037] Figures 1 and 2 illustrate a multilayer pipe 10, the multilayer pipe 10 being configured to be shock resistant, i.e. a pipe 10 configured to withstand compression and / or tensile and / or shear stresses.

[0038] According to the first embodiment of the invention, the multilayer pipe 10 has a cylindrical shape and extends between a first end 10a and a second end 10b. The pipe 10 has an opening 11 of constant diameter D to allow the passage of a fluid F from the first end 10a to the second end 10b. The opening 11 defines an internal space 11' of the pipe 10. In particular, the diameter D of the opening 11 is configured to allow the passage of a predetermined flow rate of fluid F.

[0039] The fluid F can be any fluid or gas, for example, Newtonian (or mixture of fluid or gas) injected at the first end 10a of the pipe 10 to reach the second end 10b. For example, the fluid F can be water, oil, a coolant or even a fuel.

[0040] In practice, the diameter D of the opening 11 is greater than or equal to 40 mm, preferably greater than or equal to 50 mm. Alternatively or in addition, the opening 11 of the pipe 10 is configured to support a fluid flow rate F greater than or equal to 30 L / min, preferably greater than or equal to 45 L / min.

[0041] As illustrated in the cross-sectional view of [Fig.1], the multilayer pipe 10 has an inner wall 12, an intermediate layer 14 and an outer wall 16, the intermediate layer 14 extending coaxially between the inner wall 12 and the outer wall 16.

[0042] The inner wall 12 of the pipe 10 has a tubular shape and delimits the internal space 11' of the pipe 10. The inner wall 12 is configured to accommodate the fluid F and is suitable for adapting to different system geometries. Thus, the inner wall 12 comprises a material that is both watertight and semi-rigid; preferably, it is made of a watertight and semi-rigid material. Furthermore, the inner wall 12 is capable of withstanding significant temperature variations of fluid F, for example a temperature greater than or equal to -40°C and less than or equal to 270°C.

[0043] According to the embodiment of [Fig. 1], the inner wall 12 is made of rubber, for example nitrile rubber or so-called "EPDM" rubber. The use of rubber allows the inner wall 12 to have elastic properties and consequently to be difficult to deform irreversibly. Thus, even in the event of a significant impact, the inner wall 12 of the pipe 10 is configured to elastically return to its original tubular shape.

[0044] Furthermore, the inner wall 12 has a thickness ei measured radially over a given section, which allows the pipe 10 to withstand high fluid flow rates F over the long term. The thickness ei of the inner wall 12 also increases the overall mechanical strength of the pipe 10.

[0045] The outer wall 16 of the pipe 10 has a tubular shape and surrounds the inner wall 12, so that the inner wall 12 and outer wall 16 together delimit an intermediate inner space 14' of the pipe 10 which extends radially between the inner wall 12 and the outer wall 16.

[0046] The outer wall 16 is configured to protect the pipe 10 from impacts it may experience. In particular, the outer wall 16 is capable of withstanding significant predetermined tensile, compressive, and shear stresses.

[0047] In this sense, the outer wall 16 comprises or is made of rigid and resistant material(s), preferably one or more polymer(s), for example polyethylene, polyurethane, and / or one or more composite material(s), for example carbon fibers, glass fibers or Kevlar®.

[0048] According to the first embodiment of the invention, to reinforce the pipe 10, the outer wall 16 may include reinforcing means 17 that increase the strength and durability of the pipe 10. The reinforcing means 17 may be a rigid mesh surrounding the outer wall 16 and providing additional protection, enabling the pipe 10 to withstand shear stresses and preventing the outer wall 16 from being pierced or cut by an external element during an impact. To this end, the rigid mesh may, for example, include one or more metallic materials wrapped around the outer wall 16 of the pipe 10, from the first end 10a to the second end 10b.

[0049] Furthermore, the reinforcement means 17 can be covered with a coating (not shown in the figures) which is for example sprayed or spread on the reinforcement means 17 and which protects the pipe 10 against any external degradation, for example against corrosion.

[0050] The pipe 10 comprises, between the inner wall 12 and the outer wall 16, more precisely in the intermediate internal space 14', an intermediate layer 14 of A non-Newtonian material fills the intermediate interior space 14'. This non-Newtonian material can be a fluid and / or a non-Newtonian gel. The intermediate layer 14, through its non-Newtonian properties, allows the pipe 10 to remain flexible during installation and to solidify upon impact. Thus, during an impact, the resistance of the pipe 10 is amplified by the solidification of the intermediate layer 14. Indeed, the solidification of the intermediate layer 14 partially or even completely reduces the stresses exerted by the impact on the inner wall 12 of the pipe 10 and limits the elastic, or even plastic, deformation of the inner wall 12.

[0051] Experimental results obtained from the use of a multilayer pipe 10 are described below, in which: • the diameter D of the opening 11 is greater than or equal to 40 mm, • the thickness ei of the internal wall 12 is greater than or equal to 3 mm and less than or equal to 6 mm, for example equal to 4 mm, • the thickness e2 of the non-Newtonian material layer 14 is greater than or equal to 1 mm and less than or equal to 15 mm, for example equal to 10 mm. • the thickness e3 of the external wall 16 is greater than or equal to 1 mm and less than or equal to 5 mm, preferably even less than or equal to 3 mm, for example equal to 2 mm.

[0052] Such a multilayer pipe 10 is capable of withstanding an average compressive stress greater than or equal to 5000 Pa, preferably greater than or equal to 7500 Pa, for example equal to 10000 Pa. Furthermore, for the use of such a pipe 10, the layer of non-Newtonian material absorbs a stress of 9000 Pa and transmits a stress of 1000 Pa to the inner wall 12 of the multilayer pipe 10.

[0053] In general, to guarantee a 10-layer multilayer pipe resistant to stress: • the ratio of the thickness e2 of the intermediate layer 14, measured radially, to the thickness e3 of the outer wall 16, measured radially, is greater than or equal to 0.3, and less than or equal to 15, for example equal to 2; and / or • the ratio of the thickness e2 of the intermediate layer 14, measured radially, to the thickness ei of the internal wall 12, measured radially, is greater than or equal to 0.2, and less than or equal to 5, for example equal to 0.4.

[0054] According to another embodiment of the invention, not shown in the figures, the multilayer pipe 10 has at least one additional layer of material, included between the inner wall 12 and the outer wall 16, which allows the pipe 10 to be mechanically reinforced and / or made more flexible.

[0055] Furthermore, to ensure the adhesion of the intermediate layer 14 with the inner wall 12 and with the outer wall 16 of the pipe 10: • The multilayer pipe 10 may include bonding agents placed between the inner wall 12 and the intermediate layer 14 and between the intermediate layer 14 and the outer wall 16 of the pipe 10; and / or • the multilayer pipe 10 may include an internal coating applied between the inner wall 12 and the intermediate layer 14 and between the intermediate layer 14 and the outer wall 16, the coating being for example a paste or a hardening liquid ensuring in particular the sealing of the pipe 10, the coating preferably being made of polytetrafluoroethylene (PTFE); • the inner wall 12 and the outer wall 16 of the pipe 10 can be formed by co-extrusion processes.

[0056] An example of the use of the multilayer pipe 10 in a hybrid or electric vehicle 100 is described below, with reference to figures 3 to 5.

[0057] The vehicle 100 as shown in the figures comprises a front area A including front wheels 100a, a rear area B including rear wheels 100b and a central area C extending between the front area A and the rear area B.

[0058] The vehicle 100 includes a housing 110 and a battery pack 120 disposed under a floor of the vehicle 100, between the front wheels 100a and the rear wheels 100b of the vehicle 100, in the central area C of the vehicle 100. In particular, the battery pack 120 includes a plurality of battery modules, a mounting interface and connection terminals.

[0059] In addition, the vehicle 100 includes an external access 111, that is to say an opening formed in the casing 110 of the vehicle 100 and allowing access to an internal space 112 of the vehicle 100. Furthermore, the battery pack 120 includes an emergency access 121 which is in the form of an opening allowing access to an internal space 122 of the battery pack 120.

[0060] The multilayer pipe 10 as described above, allows the external access 111 of the vehicle 100 to be connected to the emergency access 121 of the battery pack 120. In particular, the entire pipe 10 is placed in the internal space 112 of the vehicle 100, the first end 10a of the pipe 10 being connected to the external access 111 of the vehicle 100 and the second end 10b of the pipe 10 being connected to the emergency access 121 of the battery pack 120.

[0061] Such an arrangement of the multilayer pipe 10 allows access to the internal space 122 of the battery block 120 in the event of a malfunction of the battery block 122.

[0062] In particular, in the example illustrated in figures 3 to 5, such a pipe 10 is provided to discharge an extinguishing fluid F' into the internal space 122 of the battery block 120, so as to fill the internal space 122 with extinguishing fluid F' when the battery block 120 undergoes thermal runaway.

[0063] Thus, the multilayer pipe 10 is configured to convey large flows of extinguishing fluid F' from the external access 111 of the vehicle 100 into the internal space 122 of the battery pack 120.

[0064] Moreover, the resistance of the multilayer pipe 10 allows it to be functional even after an impact or deformation of the casing 101 of the vehicle 100, for example after an accident.

[0065] As illustrated in Figures 3 to 5, the pipe 10 can have different locations in the vehicle 100, in particular: • according to the embodiment of [Fig.3], the external access 111 can be located in the rear area B of the vehicle 100, and the emergency access 121 can be located in a rear area of ​​the battery pack 120, a short distance from the rear wheels of the vehicle 100; • according to the embodiment of [Fig.4], the external access 111 can be located in the central area C of the vehicle 100, and the internal access 121 can be located in a central area of ​​the battery pack 120, at an equal distance from the front wheels and the rear wheels of the vehicle 100; • according to the embodiment of [Fig.5], the external access 111 can be located in the front area A of the vehicle 100, and the internal access 121 can be located in a front area of ​​the battery pack 120, at a short distance from the front wheels of the vehicle 100.

[0066] In addition, the geometric arrangement of the pipe 10 can vary according to its location in the interior space 112 of the vehicle 100, thanks to the semi-rigid inner layer 12 and the intermediate layer 14 of non-Newtonian material which allow the pipe 10 to be flexible.

[0067] Thus, such a pipe 10 can be integrated into any type of vehicle 100, whether the vehicle is thermal, hybrid or electric, and for any external access 111 of said vehicle 100. The pipe 10 is also suitable for adapting to different internal access points 121 of the vehicle 100, whether they are located in a front, rear or central area of ​​the vehicle 100.

[0068] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0069] For example, the multilayer pipe 10 can be used in any other mechanical system requiring the conveyance of a fluid F from an inlet of the system to an outlet of the system, the system being likely to be subjected to stresses.

[0070] It is emphasized that all the features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other Specific characteristics, both individually and in any combinations, may be combined with other characteristics or groups of characteristics disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

Demands

1. Multilayer pipe (10), characterized in that it comprises at least: a semi-rigid tubular inner wall (12) delimiting an internal space (11') of the pipe (10); an outer wall (16) of tubular reinforcement surrounding the inner wall (12), the outer wall (16) being reinforced by reinforcing means (17); the multilayer pipe (10) comprising an intermediate layer (14) extending between the inner (12) and outer (16) walls and comprising at least one non-Newtonian material such as a non-Newtonian fluid or gel.

2. Multilayer pipe (10) according to claim 1, characterized in that the non-Newtonian material consists of a shear-thickening non-Newtonian fluid and / or gel.

3. Multilayer pipe (10) according to any one of the preceding claims, characterized in that it comprises a protective layer surrounding the outer wall (16) of reinforcement.

4. Multilayer pipe (10) according to any one of the preceding claims, characterized in that the inner wall (12) is watertight.

5. Multilayer pipe (10) according to any one of the preceding claims, characterized in that the inner wall (12) is made of rubber, preferably made of rubber.

6. Multilayer pipe (10) according to any one of the preceding claims, characterized in that the intermediate layer (14) is configured to be impact resistant.

7. Multilayer pipe (10) according to any one of the preceding claims, characterized in that the outer wall (16) of reinforcement is configured to resist shear stresses.

8. Multilayer pipe (10) according to any one of the preceding claims, characterized in that the reinforcement means (17) of the outer wall (16) of reinforcement comprise a rigid mesh.

9. Vehicle (100) characterized in that it comprises an external access (111) to an internal space (112) of the vehicle (100) and a multilayer pipe (10) according to any one of the preceding claims, the multilayer pipe (10) being able to connect the external access (111) to the internal space (112) of the vehicle (100).

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