Plastic hose with heat-resistant properties

Abstract

Plastic hose (1, 1') with heat-resistant properties, comprising: - a hose wall (2) made of plastic, - a reinforcement (5) made of plastic or metal, wherein the reinforcement (5) has a higher stiffness than the hose wall (2), - an outer layer (6) made of a metal foil (7), and - a thermally insulating intermediate layer (10) arranged between the tube wall (2) and the outer layer (6), characterized in that the intermediate layer (10) is made of a glass fiber mat and / or an aramid fiber mat, that the intermediate layer (10) is bonded to the tube wall (2) and to the outer layer (6), and that the tube wall (2) is made of one or more spirally wound plastic strips (3).

Description

[0001] The invention relates to a plastic hose with heat-resistant properties, comprising: a hose wall made of plastic, and a reinforcement made of plastic or metal, wherein the reinforcement has a higher stiffness than the hose wall. The plastic hose further comprises an outer layer made of a metal foil and a thermally insulating intermediate layer. The thermally insulating intermediate layer is arranged between the hose wall and the outer layer.

[0002] The invention also relates to the use of such a plastic hose in a vehicle.

[0003] Numerous different types of hoses are known in the field of hose technology. Due to its advantageous material properties and low cost, plastic is frequently used in hose manufacturing. Such hoses are referred to as plastic hoses or all-plastic hoses.

[0004] US Patent 3,109,460 A discloses a plastic hose with heat-resistant properties, comprising: a hose wall made of plastic, and a reinforcement made of plastic or metal, wherein the reinforcement has a higher stiffness than the hose wall. EP Patent 2,458,253 A1 discloses a wound hose with a material strip wound helically to form the wound hose and a reinforcement wound helically on the outside of the wound hose. US Patent 2003 / 0188,792 A discloses a flexible pipe construction and a manufacturing process in which the pipe is formed from a continuously wound elongated element. DE Patent 28,010,55 A1 discloses a flexible and compressible channel for transporting fluids with a supple tubular wall and a deformable helical reinforcement.US Patent 2006 / 0051547A1 discloses an air duct hose, and in particular an air duct hose, that is fire-resistant and flame-retardant against high flame and gas temperatures and minimizes the formation of toxic gases during combustion. Finally, US Patent 4942903A discloses a method for manufacturing fire- and corrosion-resistant articles such as pipes and / or pipe systems.

[0005] One disadvantage of all-plastic hoses, however, lies in their relatively low heat resistance. Due to their lower melting point compared to metals, all-plastic hoses can ignite and produce smoke when exposed to high temperatures – for example, in a fire. Depending on the materials used, toxic gases can also be released in a fire. To prevent health risks, strict regulations governing the fire behavior of certain materials and components exist for many applications. For example, the standard DIN EN 45545-2 ("Railway applications – Fire protection in railway vehicles – Part 2: Requirements for the reaction to fire of materials and components") applies to railway vehicles.

[0006] Based on prior art, replacing solid plastic hoses with metal hoses has already been proposed as a solution to this problem. These could be, for example, hoses with a metallic braid or with flexibly connected, ring-shaped metal elements. However, in addition to higher costs, the use of metal hoses has the disadvantage that metal hoses often leak and are significantly less flexible than plastic hoses. This results in disadvantages, for example, when laying the hoses, as only larger bending radii are possible with such hoses. Another disadvantage of metal hoses is their greater mass, which is particularly undesirable in mobile applications (e.g., in vehicles).

[0007] The invention is therefore based on the objective of designing and further developing a plastic hose mentioned at the outset and described in more detail above in such a way that the plastic hose has improved temperature resistance and, in particular, does not start to melt or burn even under strong heat exposure and causes only very little smoke development.

[0008] This problem is solved in a hose according to the preamble of claim 1 by the fact that the intermediate layer is made of a glass fiber mat and / or an aramid fiber mat and the intermediate layer is bonded to the hose wall and to the outer layer.

[0009] A hose according to the invention is characterized, firstly, by a hose wall made of plastic. Plastics offer the advantages of variable shaping, high flexibility, low weight, and low cost. Furthermore, the hose has a reinforcement made of plastic or metal, the reinforcement having a higher stiffness than the hose wall. A reinforcement is understood to be a strengthening of the hose that increases its stiffness—that is, its resistance to deformation. The increased stiffness compared to the hose wall can be achieved by making the reinforcement from a different plastic than the hose wall or from metal. Alternatively, the hose wall and the reinforcement can also be made of the same plastic but contain different additives to achieve different mechanical properties.Metal reinforcements, especially those made of steel, offer the advantage of exceptionally high rigidity; they can also dissipate electrical charges and thus balance electrical charge concentrations. The thickness or diameter of the reinforcement can range from 0.3 mm to 5 mm.

[0010] According to the invention, the hose has an outer layer made of a metal foil. This outer layer allows for a combination of the advantageous properties of both solid plastic and metal hoses. On the one hand, a metal foil exhibits high temperature resistance (typical of metals). Therefore, even in direct contact with flames, there is no risk of melting materials and the associated smoke development. The metal foil thus serves to shield the other—inner—parts of the hose from high temperatures and flames. Furthermore, metal foils are virtually airtight, so the flammability of the plastic hose is reduced simply by cutting off the oxygen supply. In addition, metal foils are particularly well-suited to reflecting heat radiation and thus keeping it away from the other parts of the hose.On the other hand, a metal foil hardly restricts, or doesn't restrict at all, the high flexibility of a plastic tube. This is due to the thinness of the foil and the fact that metal foils are usually annealed after rolling, thus regaining their elasticity and flexibility. The metal foil preferably has a thickness between 0.01 mm and 0.2 mm.

[0011] The design of the plastic hose incorporates an outer layer made of aluminum foil. Aluminum offers the advantage of a particularly low density, thus maintaining the lightweight properties generally valued in plastic hoses despite the additional outer layer. Furthermore, aluminum foils are more economical than many other metal foils due to large production volumes (e.g., for the food industry). Finally, aluminum foil reflects a significant portion of heat radiation and also exhibits lower thermal conductivity than silver, copper, and gold. This results in minimal heating of the plastic hose wall in the event of a fire.

[0012] According to a further development of the plastic hose, it is proposed that the outer layer be bonded to the hose wall. Bonding has the advantage that, despite the different material pairing of plastic / metal foil, a secure and reliable connection between the hose wall and the outer layer can be achieved. Furthermore, a full-surface bond can be achieved, so that no protruding areas of the outer layer are a concern. In addition, bonding processes – unlike, for example, thermal joining processes – are also suitable for joining particularly thin materials such as films. Finally, the adhesive can provide thermal insulation between the outer layer and the hose wall, which reduces heat conduction and thus further increases the temperature resistance of the hose.

[0013] Regarding the outer layer, a further embodiment of the plastic tube proposes that the outer layer be made from one or more spirally wound strips of film. This manufacturing method is based on the idea of ​​first providing a strip of metal foil and then forming the outer layer of the tube by spirally winding and bonding it. This approach also allows for the production of tubes with a length greater than the width of the metal foil (which is limited by the rolling process). Preferably, the outer layer is made exclusively from one or more spirally wound strips of film and, in particular, does not have any further unwound layers or plies.

[0014] For this design, it is further proposed that the foil strip forming the outer layer has overlapping edge areas that are connected, in particular glued, to each other in the overlap area. The overlap provides a sufficiently large surface area for the formation of a particularly reliable adhesive bond.

[0015] Another embodiment of the plastic hose, as well as the plastic hose according to the invention, is characterized by a thermally insulating intermediate layer arranged between the hose wall and the outer layer. A thermally insulating layer is understood to be, in particular, a layer that provides better thermal insulation than the outer layer. Preferably, the intermediate layer therefore has a lower thermal transmittance coefficient than the outer layer. The intermediate layer thermally insulates the metallic outer layer from the plastic hose wall. This is particularly desirable because, although the metallic outer layer is very temperature-resistant and also reflects some of the thermal radiation, it also has a relatively high thermal conductivity and thus transfers heat energy to the plastic hose wall.The intermediate layer thus serves to reduce heat conduction between the outer layer and the hose wall. A further effect of the intermediate layer is to compensate for unevenness in the hose wall (e.g., in the area of ​​the reinforcement) and thus create a flatter contact surface for the outer layer. Preferably, the intermediate layer has a thickness between 0.3 mm and 3.5 mm.

[0016] According to the invention, the intermediate layer is made of a glass fiber mat and / or an aramid fiber mat.

[0017] This design further proposes that the intermediate layer be made of a fiber mat, particularly a glass fiber mat. Alternatively or additionally, mats made of aramid fibers or other suitable fibers can be used (e.g., "Nomex" or "Kevlar," both registered trademarks of DuPont). The fiber mats can be woven or nonwoven. One advantage of fiber mats is their excellent thermal insulation, as they typically contain many air pockets. Furthermore, fiber mats made with the fibers typically used (e.g., glass fibers) exhibit very high temperature resistance. Additionally, fiber mats are soft and elastic and can therefore compensate particularly well for irregularities in the hose wall (e.g., in the reinforcement area). This has the advantage, for example, that the metal foil forming the outer layer is less likely to tear when the plastic hose is bent.Preferably, the intermediate layer is made exclusively from a fiber mat and, in particular, has no further layers or plies. Fiber mats with a basis weight in the range of 100 g / m² are preferred. 2 and 800 g / m² 2 .

[0018] In a further embodiment of the plastic hose, as well as in the plastic hose according to the invention, the intermediate layer is bonded to the hose wall and the outer layer. Bonding offers the advantage that, despite the different material pairing of plastic / fiber material / metal foil, a secure and reliable connection can be achieved between the hose wall, the intermediate layer, and the outer layer. Furthermore, a full-surface bond can be achieved, so that no protruding areas of the outer layer are a concern. Additionally, bonding processes—unlike, for example, thermal joining processes—are also suitable for joining particularly thin materials such as films. Finally, the fiber material is particularly suitable for being impregnated with adhesive, thus creating a double-sided bond with the hose wall and the outer layer.

[0019] Another design of the plastic hose involves a hose wall made of a thermoplastic material, particularly a thermoplastic elastomer. Examples include TPU (thermoplastic polyurethane), PVC (polyvinyl chloride), PE (polyethylene), TPE (thermoplastic elastomer), or TPR (thermoplastic rubber). The plastic may contain a filler such as talc or chalk, and / or flame retardant additives to reduce the burning rate and smoke emissions.

[0020] Following further development of the plastic hose, it is proposed that the hose wall be manufactured from one or more spirally wound plastic strips. The underlying principle of this manufacturing method is to first extrude a plastic strip, rather than extruding the hose wall itself. This has the advantage that plastic or metal reinforcements can be integrated into the plastic strip during the extrusion process. Subsequently, a hose wall is formed from the plastic strip by spiral winding and welding or bonding. This approach allows for the production of hose walls with more complex structures than are possible using extrusion methods. Preferably, the hose wall is manufactured exclusively from one or more spirally wound plastic strips and, in particular, has no further unwound layers or plies.Such a hose is also called a "wound hose" due to the spiral winding of plastic strips; a method for its manufacture is described, for example, in DE 198 48 172 Al.

[0021] In a further development of the plastic hose, it is proposed that the plastic strip forming the hose wall has overlapping edge regions which are bonded together in the overlap area. This bond can be achieved, in particular, by adhesive bonding and / or welding. A bond ensures a particularly reliable seal at the seam. Furthermore, the overlap provides a sufficiently large surface area for the formation of the connection.

[0022] Another embodiment of the plastic hose features a spiral reinforcement. Alternatively, the reinforcement can be ring-shaped. The reinforcement is thus wrapped around the hose. In particular, the reinforcement can run spirally or ring-shaped around a central axis extending along the longitudinal direction of the hose. Such reinforcement has the advantage of increasing the hose's stiffness in the radial direction, thus maintaining the hose's cross-sectional shape—preferably round—in the reinforced area. At the same time, a spiral or ring-shaped reinforcement only minimally or not at all increases the bending stiffness, so that a hose with such reinforcement can still be bent and laid in curves.Another advantage of spiral or ring-shaped reinforcements is that the hose can be compressed longitudinally.

[0023] Regarding the arrangement of the reinforcement, a further development of the plastic hose proposes that the reinforcement be positioned between the overlapping edge regions of the plastic strip. This can be, in particular, the plastic strip that forms the hose wall. This arrangement protects the reinforcement from environmental influences, thereby reducing the risk of corrosion, for example. Specifically, the reinforcement can be arranged in a cavity formed between the overlapping edge regions of the plastic strip. The cavity allows for a defined arrangement and positioning of the reinforcement. Furthermore, the arrangement within the cavity provides particularly good protection against environmental influences. The cavity can be created, for example, by two parallel, spaced-apart welds or adhesive seams.

[0024] Alternatively, it is proposed that the reinforcement be integrated into the plastic strip. This can also refer specifically to the plastic strip that forms the hose wall. Integration of the reinforcement can be achieved by incorporating it into the plastic strip during extrusion. This has the advantage that the reinforcement does not need to be added during welding of the plastic strip, as it is already present within the strip.

[0025] The plastic hose described above, in all its illustrated configurations, is particularly well-suited for use in motor vehicles, especially rail vehicles. This is primarily due to its combination of low weight, good heat resistance, and low smoke emission.

[0026] The invention is explained in more detail below with reference to a drawing that illustrates only a preferred embodiment. The drawing shows: Fig. 1 a first embodiment of a hose according to the invention in a sectional view, and Fig. 2 a second embodiment of a hose according to the invention in a cutaway view.

[0027] Fig. Figure 1 shows a first embodiment of a hose 1 according to the invention in a sectional view. The hose 1 comprises a hose wall 2 made from a plastic strip 3. In this manufacturing process, the plastic strip 3 is wound spirally, with the edge regions of the plastic strip 3 forming an overlap 4. The overlapping edge regions of the plastic strip 3 are then welded or glued together to achieve a reliable seal at the seam. The hose 1 also comprises a metal reinforcement 5, for example, a wire. The reinforcement 5 is integrated into the plastic strip 3 and completely surrounded by its material. The outer surface of the plastic strip 3 is convex in the area of ​​the reinforcement 5. Finally, the hose 1 comprises an outer layer 6 made of a metal foil 7.To produce the outer layer 6, the metal foil 7 is wound spirally, with the edge areas of the metal foil 7 forming an overlap 8. The tube 1 produced in this way runs symmetrically around a central axis 9 extending in the longitudinal direction of the tube 1.

[0028] In Fig. Figure 2 shows a second embodiment of a hose 1' according to the invention in a sectional view. Those areas of the hose 1' that have already been described in connection with Fig. As described in section 1, are in Fig. 2 with corresponding reference numerals. The essential difference to the one in Fig. The reason for the hose shown in 1 is that the one in Fig. As shown in Figure 2, the tube 1' comprises an intermediate layer 10 arranged between the tube wall 2 and the outer layer 6. The intermediate layer 10 is made of a fiber mat 11 wrapped around the tube wall 2. Unlike the plastic strip 3 and the metal foil 7, the edge regions of the fiber mat 11 are not arranged overlapping due to their thickness, but are merely placed side by side, touching edge to edge, thus creating seams 12. The fiber mat 11 can be wound spirally around the tube wall 2, creating spirally circumferential seams 12. Alternatively, and unlike in Figure 2, the fiber mat 11 can be wrapped in a spiral pattern around the tube wall 2, creating spirally circumferential seams 12. Fig. 2 shown - the fiber mat 11 can also be wrapped around the tube wall 2 in a ring shape; in this case, circumferential seams 12 would be created. Reference symbol list: 1, 1' hose or plastic hose 2 hose wall 3 plastic strips 4 Overlap (of the plastic strip 3) 5 Reinforcement 6 Outer layer 7 Metal foil or metal foil strips 8 Overlap (of the metal foil 7) 9 Central axis 10 Intermediate shift 11 Fiber mat 12. Seam (of the fiber mat 11)

Claims

A plastic hose (1, 1') with heat-resistant properties, comprising: - a hose wall (2) made of plastic, - a reinforcement (5) made of plastic or metal, wherein the reinforcement (5) has a higher stiffness than the hose wall (2), - an outer layer (6) made of a metal foil (7), and - a thermally insulating intermediate layer (10) arranged between the hose wall (2) and the outer layer (6), characterized in that the intermediate layer (10) is made of a glass fiber mat and / or an aramid fiber mat, that the intermediate layer (10) is bonded to the hose wall (2) and to the outer layer (6), and that the hose wall (2) is made of one or more spirally wound plastic strips (3). Plastic hose according to claim 1, characterized in that the outer layer (6) is made of an aluminum foil (7). Plastic hose according to one of claims 1 to 2, characterized in that the outer layer (6) is made from one or more spirally wound film strips (7). Plastic hose according to claim 3, characterized in that the film strip (7) forming the outer layer (6) has overlapping edge areas which are connected to each other in the area of ​​the overlap (8), in particular glued. Plastic hose according to one of claims 1 to 4, characterized in that the hose wall (2) is made of a thermoplastic plastic, in particular of a thermoplastic elastomer. Plastic hose according to claim 1, characterized in that the plastic strip (3) forming the hose wall (2) has overlapping edge areas which are bonded together in the area of ​​the overlap (4). Plastic hose according to one of claims 1 to 6, characterized in that the reinforcement (5) is spirally shaped. Plastic hose according to one of claims 1 to 7, characterized in that the reinforcement (5) is arranged between the overlapping edge regions of the plastic strip (3). Plastic hose according to one of claims 1 to 7, characterized in that the reinforcement (5) is integrated into the plastic strip (3). Use of a plastic hose (1, 1') according to any one of claims 1 to 9 in a vehicle. Use of a plastic hose (1, 1') according to claim 10, characterized in that the vehicle is a rail vehicle.

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