Fluid line comprising a multi-layer pipe

Abstract

The invention relates to a fluid line (10) comprising a multi-layer pipe which extends in a longitudinal direction (L) and is formed by at least two layers, the multi-layer pipe having an inner layer (1) and an outer layer (3). According to the invention, the inner layer (1) comprises a hydrolysis-resistant reinforcing material with the outer layer (3) comprising a flexible plastics material, a radial extent of the inner layer (1) in the radial direction (R) corresponding to at most approximately one third of a radial extent of the outer layer (3) in the radial direction (R).

Description

[0001] Fluid line with a multilayer pipe

[0002] The invention relates to a fluid line with a multilayer pipe according to the preamble of claim 1.

[0003] Pipes used to transport fluids, such as in hydraulic or high-temperature systems (HTS) applications, or various applications in vehicles, must meet specific requirements during operation. For example, the fluid must not dissolve the pipe material. This should be avoided, especially at higher temperatures and pressures.

[0004] Furthermore, the fluid line or multilayer pipe must meet increased burst pressure requirements and withstand mechanical stresses, especially in high-temperature applications above 100 °C or hydraulic applications. In some hydraulic or HTS applications, burst pressures greater than 50 bar at temperatures above 100 °C may be required. Additionally, the fluid lines must possess mechanical properties that allow for a simple and secure connection to other line components. For this purpose, it is advantageous for the line to exhibit a certain degree of flexibility while simultaneously possessing sufficient stiffness and burst strength.

[0005] Furthermore, the multilayer pipe or fluid line must be impermeable to the transported fluid and its chemical components to prevent the fluid from penetrating the pipe wall. This is intended to prevent both a reduction in the quality of the transported fluid and the fluid from penetrating the pipe wall, thus avoiding changes to the pipe wall material. The use of multilayer plastic pipes is known.

[0006] Multilayer plastic pipes, such as those made of polyamide, are used. These plastic pipes contain materials that exhibit the aforementioned properties, for example, in relation to water or water-containing fluids. However, these plastics and their processing are expensive.

[0007] A further disadvantage is that the well-known standard solutions, which generally rely on cheaper standard plastics such as polyamide or polypropylene, or other plastics, often cannot meet the increased burst pressure requirements and mechanical stresses in certain applications. Other standard pipe materials also cannot withstand such increased stresses.

[0008] The aim of the invention is to overcome these and other disadvantages of the prior art and to provide an improved fluid line with a multilayer pipe that is easy and inexpensive to manufacture.

[0009] The main features of the invention are specified in the characterizing part of claim 1. Embodiments are the subject of further claims 2 to 15.

[0010] In a fluid line with a multilayer pipe extending along a longitudinal direction and formed by at least two layers, wherein the multilayer pipe has an inner layer and an outer layer, it is provided according to the invention that the inner layer comprises a hydrolysis-resistant reinforcing material, wherein the outer layer comprises a flexible plastic material, wherein a radial extent of the inner layer in the radial direction corresponds at most to approximately one third of a radial extent of the outer layer in the radial direction.

[0011] As described at the beginning, increased burst pressures and temperatures occur particularly in the area of ​​hydraulic or high-temperature piping applications.

[0012] The core of the invention is the use of a multi-layer pipe comprising one or more layers of hydrolysis-resistant reinforcing material, such as glass fibers or carbon fibers. Burst pressure, burst strength, or burst resistance is a technical term that represents a quality characteristic for pipes, hoses, tires, containers and pressure vessels, as well as for films, membranes, papers, and cardboards. The stressed elements fail when the burst pressure is reached; this can cause an explosion in the event of sudden failure. The burst pressure is generally determined using suitable testing methods and is expressed in kPa or bar. It is typically many times higher than the permissible nominal pressure, for example, in a pipe system.Furthermore, burst pressure is a determining factor in the underground rehabilitation and destruction of old pipes, where, under the influence of a so-called bursting body on the inner pipe wall, it can be destroyed and the pipes removed.

[0013] The hydrolysis-resistant reinforcement material of the inner layer according to the invention advantageously not only effectively improves the hydrolysis resistance of the fluid line due to the reinforcement. At the same time, this measure also significantly improves the burst strength or burst performance and the mechanical load-bearing capacity.

[0014] In particular, the precisely defined ratio of approximately two-thirds flexible plastic material to one-third hydrolysis-resistant reinforcing material, relative to the total radial extent of the multilayer pipe, results in a smaller reinforced portion of the pipe compared to the flexible portion, exhibiting less radial expansion. This ensures that, despite the reinforcing material in the inner layer, a minimum degree of flexibility is always maintained in the fluid line. This significantly simplifies the installation and connection of the fluid line to other components such as quick-connect fittings or deflectors. Simultaneously, the reinforcing material provides increased stiffness, which considerably enhances burst strength.

[0015] According to a preferred embodiment, the hydrolysis-resistant reinforcing material of the inner layer can be glass or carbon fiber reinforced. It has been found that significantly better burst performance can be achieved with glass or carbon fiber reinforced material. Due to the glass or carbon fibers, or alternatively other similar reinforcing materials of the inner layer, the fluid line can be reliably used, particularly in hydraulic or high-temperature applications with pressures up to 60 bar and temperatures of approximately 115 °C, without failing or exploding due to the increased stress. According to another preferred embodiment, the multilayer pipe can be manufactured by an extrusion process.The use of glass fibers is well-known for injection-molded parts, but not for extruded tubes, which are used, for example, in the automotive industry. Extrusion is one of the most widespread processes in the plastics processing industry. Thanks to its numerous advantages, particularly in terms of efficiency, it has gained considerable importance, especially in series production. This allows for the advantageous and cost-effective production of multi-layer tubes. For example, in direct comparison to injection molding, no two-part dies or similar components are required to produce three-dimensional shapes. Another significant advantage of extrusion is that very complex shapes and tubes with relatively long longitudinal extensions can be produced with minimal effort. Furthermore, extrusion makes it possible to process both soft and brittle materials.Further advantages of extrusion can include high flexibility during the manufacturing process, high throughput, and lower personnel requirements for implementation.

[0016] Preferably, the outer layer can also be free of hydrolysis-resistant reinforcing material.

[0017] According to another preferred alternative embodiment, the outer layer can extend circumferentially around the inner layer.

[0018] In this case, the outer flexible plastic layer is positioned further out in the fluid line than the inner hydrolysis-resistant reinforced layer.

[0019] According to a further preferred embodiment, the fluid line can have at least one first intermediate layer, wherein the at least one first intermediate layer can be arranged between the inner layer and the outer layer of the multilayer tube.

[0020] The first intermediate layer can therefore be a base layer, which can be shielded inwards by the inner layer and outwards by the outer layer.

[0021] The first intermediate layer is thus located on the fluid line, on the outside when viewed from the inner layer and on the inside when viewed from the outer layer. Preferably, the first intermediate layer can comprise a hydrolysis-resistant reinforcing material or a flexible plastic material. This allows the multilayer pipe to be made even stiffer or more flexible as needed and is therefore individually adaptable to load profiles.

[0022] According to a further preferred embodiment, the fluid line can have a further second intermediate layer, wherein the second intermediate layer can be arranged between the first intermediate layer and the inner layer.

[0023] It is further preferably conceivable that the second intermediate layer can comprise a flexible plastic material, wherein the second intermediate layer of the multilayer tube can be free of hydrolysis-resistant reinforcing material.

[0024] According to a further preferred embodiment, the fluid line can have a further third intermediate layer, wherein the third intermediate layer can be arranged between the second intermediate layer and the inner layer.

[0025] According to another preferred embodiment, the third intermediate layer of the multilayer tube can have a hydrolysis-resistant reinforcing material.

[0026] According to a further preferred embodiment, the flexible plastic material of the outer layer and / or the first intermediate layer and / or the second intermediate layer can comprise a polyamide (PA).

[0027] Preferably, it is further conceivable that the polyamide (PA) of the individual layers of the flexible plastic material may comprise polyamide 6 (PA6) and / or polyamide 612 (PA612) and / or polyamide 610 (PA610).

[0028] Preferably, all flexible plastic layers or intermediate layers of the multilayer tube can be made of polyamide 6. Polyamide 6 is particularly cost-effective, even compared to other polyamide blends such as PA 12, and thus results in a significant overall cost reduction in the production of the multilayer tube. Since the flexible plastic component already predominates compared to the reinforcing material, less of other, more expensive materials are required. Furthermore, it is preferably conceivable that the outer layer is made of polyamide 612, while all other unreinforced flexible plastic layers can be made of polyamide 6 for cost reasons. This represents an ideal compromise between optimal external shielding and a cost-effective manufacturing price.The outer layer made of polyamide 612 offers excellent resistance to greases, oils, fuels, hydraulic fluids, water, and alkalis. When the fluid line is used in an environment where these substances can come into contact with the outer layer of the multilayer pipe, the inner layers, especially the first intermediate layer, are effectively protected by the outer layer. Thus, the outer layer forms a protective barrier against external influences for the inner layers. Furthermore, the outer layer is elastic, giving the fluid line a degree of external flexibility.

[0029] According to one embodiment, it is further conceivable that all flexible plastic layers or intermediate layers of the multilayer tube alternatively or additionally comprise polypropylene (PP) and / or polyethylene (PE) and / or polyphenylene sulfide (PPS).

[0030] Polypropylene and polyethylene both exhibit very good thermal properties and can be used as an additional barrier layer against the fluid medium flowing in the pipeline, for example, water. This could advantageously reduce the contact between the hydrolysis-resistant reinforcing material of the inner layer and, for example, water molecules.

[0031] Polypropylene sulfide has further improved thermal properties than polypropylene or polyethylene, so that it could also be used at even higher temperatures.

[0032] According to a further preferred embodiment, the flexible plastic material of the multilayer tube, which may preferably be formed by the outer layer and / or the first intermediate layer and / or the second intermediate layer, may have a radial extent of at least between 60% and 75%, preferably about two-thirds, of the total radial extent of the multilayer tube.

[0033] In other words, this means that a maximum of approximately one-third (33.33%) of the total wall thickness of the multilayer fluid line is made up of reinforcing material such as glass or carbon fibers. The remaining portion of the multilayer line is filled by the flexible or elastic plastic material of the other layers. The greater the proportion of the radial extent of the multilayer line made of the preferred, cost-effective polyamide 6, the more cost-effective the overall design and manufacturing of the fluid line becomes.

[0034] According to a further aspect, the invention relates to a hydraulic or high-temperature pipe system, for example in a motor vehicle, with at least one fluid line according to one of the preceding claims, wherein the fluid line connects the hydraulic or high-temperature pipe system and an element to be tempered in a fluid-communicating manner, wherein operating temperatures of up to 110 °C or more and burst pressures of up to 58 bar or more can preferably occur in the fluid line connected to the hydraulic or high-temperature pipe system in a fluid-communicating manner.

[0035] The advantages, effects, and further developments of the hydraulic or high-temperature piping system with a fluid line result from the advantages, effects, and further developments of the fluid line described above. Therefore, reference is made to the preceding description in this regard.

[0036] According to another aspect of the invention, the use of a fluid line for conveying a fluid in a motor vehicle is provided.

[0037] The advantages, effects, and further developments of using the fluid line result from the advantages, effects, and further developments of the fluid line described above. Therefore, reference is made to the preceding description in this regard.

[0038] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. The drawings show:

[0039] Fig. 1a a schematic representation of a fluid line with a multilayer pipe consisting of at least two layers; Fig. 1b a schematic sectional view of a first embodiment of a fluid line with three layers;

[0040] Fig. 2a shows a schematic sectional view of another embodiment of a fluid line with four layers;

[0041] Fig. 2b shows a schematic sectional view of another embodiment of a fluid line with five layers.

[0042] The fluid line, generally designated as a whole by 10 in Fig. 1a, comprises a multilayer pipe, where in Fig. 1a only an exemplary pipe or fluid line with a single layer is shown.

[0043] The fluid line 10 or the multilayer pipe extends along a longitudinal direction L and is formed by at least two pipe layers.

[0044] As can be seen from the inclusion of Fig. 1b, the multilayer pipe of the fluid line 10 has an inner layer 1 and an outer layer 3. The inner layer 1 comprises a hydrolysis-resistant reinforcing material, while the outer layer 3 comprises a flexible plastic material. The radial extent of the inner layer 1 in the radial direction R corresponds to approximately one-third of the radial extent of the outer layer 3 in the radial direction R.

[0045] In other words, the radial extent in the radial direction R corresponds to an extension of the pipe wall or a wall thickness of the multilayer pipe.

[0046] The hydrolysis-resistant reinforcement material of the inner layer 1 of the multilayer tube can be made of glass or carbon fiber reinforced material. The inner layer 1 can directly form the fluid channel through which the fluid flows and is in contact with the fluid via an inner surface. The inner layer 1 thus forms a contact layer for the fluid.

[0047] The illustrated multilayer fluid line 10 can be manufactured by means of an extrusion process. The outer layer 3 can be free of hydrolysis-resistant reinforcing material, and the outer layer 3 can extend circumferentially around the inner layer 1. That is, the outer layer 3 can directly enclose the inner layer 1, so that the inner layer 1 extends through the outer layer 3 in the longitudinal direction L and can directly abut and border the outer layer 3 in the radial direction R. The outer layer 3 can thus form the outermost layer of the multilayer pipe.

[0048] As illustrated particularly in Fig. 1b, the fluid line 1 can have at least one first intermediate layer 2, wherein the at least one first intermediate layer 2 can be arranged between the inner layer 1 and the outer layer 3 of the multilayer tube. That is, the outer layer 3 can enclose the first intermediate layer 2, and the first intermediate layer 2 can directly enclose the inner layer 1, so that the inner layer 1 can extend through and abut the first intermediate layer 2, and the first intermediate layer 2 can extend through the outer layer 3 in the longitudinal direction L and abut and border directly on the outer layer 3 in the radial direction R.

[0049] The first intermediate layer 2 can comprise a hydrolysis-resistant reinforcing material or a flexible plastic material. In the exemplary embodiment illustrated in Fig. 1b, the first intermediate layer 2, like the outer layer 3, can be a flexible plastic material that is free of hydrolysis-resistant reinforcing material.

[0050] Figures 2a and 2b show two further embodiments with fluid lines or multilayer pipes, which are collectively designated by reference numeral 10.

[0051] As can be seen from Fig. 2a, the fluid line 10 can have a further second intermediate layer 4, wherein the second intermediate layer 4 can be arranged between the first intermediate layer 2 and the inner layer 1. The second intermediate layer 4 can be in direct contact with the inner layer 1 on the inside and with the first intermediate layer 2 on the outside.

[0052] The second intermediate layer 4 can comprise a flexible plastic material, wherein the second intermediate layer 4 of the multilayer tube can be free of hydrolysis-resistant reinforcing material. As can be seen particularly from the inclusion of Fig. 2b, the fluid line 10 or the multilayer tube can further comprise a third intermediate layer 5, wherein the third intermediate layer 5 can be arranged between the second intermediate layer 4 and the inner layer 1. The third intermediate layer 5 can be in direct contact with the inner layer 1 on the inside and with the second intermediate layer 4 on the outside.

[0053] In the illustrated embodiment, the third intermediate layer 5 of the multilayer tube can comprise the hydrolysis-resistant reinforcing material analogous to the inner layer 1 or, optionally, analogous to the first intermediate layer 2. The multilayer tube of the fluid line 10 can comprise one or more layers of reinforcing material, preferably glass or carbon fibers.

[0054] The flexible plastic material of the outer layer 3 and / or the first intermediate layer 2 and / or the second intermediate layer 4 can be a polyamide (PA) in the examples shown. Possible polyamides include, for example, polyamide 6 (PA6) and / or polyamide 612 (PA612) and / or polyamide 610 (PA610).

[0055] The flexible plastic material of the multilayer tube of the fluid line 10, which is formed by the outer layer 3 and / or the first intermediate layer 2 and / or the second intermediate layer 4, can have at least between 60% and 75%, preferably about two-thirds, of the total extent of the multilayer tube in the radial direction R in the radial direction R.

[0056] The invention is not limited to the embodiments described above, but can be modified in a variety of ways. In particular, the precise alignment of the plastic layers can be advantageously varied, taking into account the application costs, provided that flexibility is maintained. The overall dimensions or the ratio between the plastic material and the reinforcing material in the multilayer tube can also be varied, such that the aforementioned compromise between stiffness and flexibility is always maintained. All other requirements mentioned at the outset are already fulfilled by the reinforcing material.

[0057] All features and advantages arising from the claims, the description and the drawing, including design details, spatial arrangements and process steps, can be essential to the invention both individually and in various combinations.

[0058] Reference numeral list

[0059] R Radial direction

[0060] L Longitudinal direction (extension direction)

[0061] 1 inner layer

[0062] 2 first intermediate shift

[0063] 3 outer layer

[0064] 4 second intermediate shift

[0065] 5 third intermediate shift

[0066] 10 Fluid line

Claims

Patent claims 1. Fluid line (10) with a multilayer tube extending along a longitudinal direction (L) and formed by at least two layers, wherein the multilayer tube has an inner layer (1) and an outer layer (3), characterized in that the inner layer (1) comprises a hydrolysis-resistant reinforcing material, wherein the outer layer (3) comprises a flexible plastic material, wherein a radial extent of the inner layer (1) in the radial direction (R) corresponds at most to approximately one third of a radial extent of the outer layer (3) in the radial direction (R).

2. Fluid conduit according to claim 1, characterized in that the hydrolysis-resistant reinforcing material of the inner layer (1) is glass or carbon fiber reinforced material.

3. Fluid line according to claim 1 or 2, characterized in that the multilayer pipe is produced by an extrusion process.

4. Fluid line according to one of the preceding claims, characterized in that the outer layer (3) is free of hydrolysis-resistant reinforcing material.

5. Fluid line according to one of the preceding claims, characterized in that the outer layer (3) extends circumferentially around the inner layer (1).

6. Fluid line according to one of the preceding claims, characterized in that the fluid line (10) has at least one first intermediate layer (2), wherein the at least one first intermediate layer (2) is arranged between the inner layer (1) and the outer layer (3) of the multilayer tube.

7. Fluid line according to claim 6, characterized in that the first intermediate layer (2) comprises a hydrolysis-resistant reinforcing material or a flexible plastic material.

8. Fluid line according to claim 6 or 7, characterized in that the fluid line (10) has a further second intermediate layer (4), wherein the second The intermediate layer (4) is arranged between the first intermediate layer (2) and the inner layer (1).

9. Fluid line according to claim 8, characterized in that the second intermediate layer (4) comprises a flexible plastic material, wherein the second intermediate layer (4) of the multilayer tube is free of hydrolysis-resistant reinforcing material.

10. Fluid line according to claim 8 or 9, characterized in that the fluid line (10) has a further third intermediate layer (5), wherein the third intermediate layer (5) is arranged between the second intermediate layer (4) and the inner layer (1).

11. Fluid line according to claim 10, characterized in that the third intermediate layer (5) of the multilayer pipe has a hydrolysis-resistant reinforcing material.

12. Fluid line according to one of claims 6 to 9, characterized in that the flexible plastic material of the outer layer (3) and / or the first intermediate layer (2) and / or the second intermediate layer (4) comprises a polyamide (PA).

13. Fluid line according to one of claims 6 to 12, characterized in that the flexible plastic material of the multilayer tube, which is formed by the outer layer (3) and / or the first intermediate layer (2) and / or the second intermediate layer (4), has a radial extent (R) of at least between 60% and 75%, preferably about two-thirds, of the total radial extent of the multilayer tube.

14. Hydraulic or high-temperature pipe system, for example in a motor vehicle, with at least one fluid line (10) according to one of the preceding claims, characterized in that the fluid line connects the hydraulic or high-temperature pipe system and an element to be tempered in a fluid-communicating manner, wherein in the fluid line connected to the hydraulic or high-temperature pipe system in a fluid-communicating manner preferably operating temperatures up to 110 °C or more and burst pressures up to 58 bar or more may occur.

15. Use of a fluid line (10) according to one of the preceding claims for conveying a fluid in a motor vehicle.

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