KR20080075097A - Fluid line and method for its production - Google Patents

Abstract

A method for producing a fluid line (2) and a corresponding fluid line (2) are specified, wherein a number of pipes are wound in parallel along a helical line in each case, a connecting element (6, 7) is fastened to at least one end and the pipes are embedded in a plastic. It is wished to make production simple. For this purpose, it is envisaged to use a liquid silicone rubber (12) as the plastic.

Description

Fluid line and its manufacturing method {FLUID LINE AND METHOD FOR ITS PRODUCTION}

The present invention relates to a method for producing a fluid line, in which several pipes are each wound along a spiral in parallel, with at least one end fixed with a connecting element and the pipes embedded in plastic. The invention also relates to a fluid line having several pipes, each guided and parallel along a spiral, the pipes having one common connection element at at least one end, wherein the pipes are embedded in plastic. .

Such fluid lines are known from WO 2004/046601 A1. The sum of the cross sections of all pipes is provided for the flow of the fluid. The spirally guided pipes allow the fluid line to be a kind of flexibility.

Such fluid lines are well suited for transporting fluids under high pressure and, optionally, at high temperatures when strong vibrations and aggressive ambient conditions are present in technical applications. Applications include CO ₂ in mobile cooling plants, especially in motor vehicles Cooling equipment. In such an application, for installation reasons, some kind of flexibility of the line is required without weakening the line.

However, the manufacture of such fluid lines requires some effort. This applies in particular to the step of embedding in plastic. At this time, in general, the pipe must be stabilized from the inside so as not to damage the pipe during landfill.

The object of the present invention is to simplify the manufacture.

This object is achieved by the use of liquid silicone rubber as plastic in the above-mentioned type of process.

Liquid silicone rubbers are plastics that offer significant advantages over conventional silicone rubbers or other polymeric plastics such as thermoplastics, elastomers or thermoplastic elastomers for this application. In this case, it is directed to a two-component plastic that is highly elastic and resistant to high temperatures, which is cured only when both components of low viscosity are connected under heat absorption. In order to sufficiently adhere the cured liquid silicone rubber to the surface of the pipe, no special pretreatment of the pipe surface is necessary. The adhesion is maintained even at 100% or more expansion. Liquid silicone rubbers are available, for example, under the names Dow Corning SILASTIC LSR, Wacker ELASTOSIL LR and GE-Bayer Silopren LSR.

Preferably, the liquid silicone rubber is applied onto the pipe in an injection molding process. The advantages of liquid silicone rubber are evident in this procedure. That is, the premixed components of the liquid silicone rubber, more specifically the liquid silicone rubber, are provided in the injection molding mold under relatively low pressure. In general, a relatively low injection pressure of up to 50 bar is sufficient. Common plastics often required several 100 bar of pressure, so the pipe had to be stabilized from the inside.

Preferably, the pipe is placed in the injection molding mold and the component mixture of liquid silicone rubber is introduced into the injection molding mold through the cooled inlet channel. With this procedure, the viscosity of the blended ingredients It can be avoided that the inflow may be high and blockages may occur. In addition, the finished line can generally be taken out of the injection molding mold without sprues.

More preferably, the pipe is heated before being placed in the injection molding mold. Liquid silicone rubber cures under heat absorption. If heat is supplied to a sufficient degree, curing can be accelerated. With sufficient heat supply, curing takes place quickly, so a short cycle time of the manufacturing procedure can be achieved in the range of a few seconds. In addition, heating the pipe to a temperature in the range of approximately 150 to 200 ° C. improves the adhesion of the liquid silicone rubber to the pipe.

Alternatively or in addition, the injection molding mold may be heated. This also causes acceleration of the curing process.

The object is achieved by the liquid silicone rubber in which the plastic is cured in a fluid line of the abovementioned type.

Cured liquid silicone rubber is a plastic that is highly elastic and resistant to high temperatures, as mentioned above. The liquid silicone rubber is formed as a two-component plastic, in which both components have a low viscosity, in a separated state and also in a mixed state for some time, i.e. a high flow capacity. At the time of connection both components are cured under heat absorption, in which case they are connected to the pipe in an excellent manner.

Preferably, the cured liquid silicone rubber covers a connecting arrangement between the pipe and the connecting element. As a result, the seams at the connection between the pipe and the connecting element are also reliably protected from corrosion attack.

More preferably, the pipes are spaced from one another, in which the cured liquid silicone rubber is arranged. In this way, friction between individual pipes is prevented in operation. This friction can cause damage to the pipe.

More preferably, the cured liquid silicone rubber surrounds the hollow space inside the interior space surrounded by the pipe. That is, the pipe is covered with liquid silicone rubber radially inside and outside. Nevertheless, a hollow space is arranged inside the line, in which there is no cured liquid silicone rubber. This form has the advantage that other lines, such as electrical lines, can be guided through the hollow space in addition to the advantages of weight saving.

More preferably, the connecting element is arranged outside of the longitudinal axis of the helix. This allows the insertion of the core in the manufacture of the line to create a hollow space. In other words, in this case, the connecting element does not interfere with the movement of the core during introduction and withdrawal.

Preferably, the ends of the pipe protrude tangentially with respect to the helix. In this case, the ends do not need to bend at the end of the helix and continue so-called straight.

According to an alternative form, the ends of the pipe can be bent parallel to the longitudinal axis of the helix. In this case, so-called connection elements extending in a straight line from the fluid line can be used.

More preferably, the connecting element has a base plate with through openings in which ends of the pipe are inserted. Which connects pipes It is a relatively simple possibility to connect with the element and at the same time make it safe for this connection to be sealed.

Preferably, the base plate together with the housing element defines a connection space, wherein the housing element has an opening. The opening may later be connected with another line or junction, in which fluid must be supplied or discharged. The base plate and the housing element can be manufactured separately and later connected. The base plate and the housing element may be integrally formed.

More preferably, the ends of the pipe are connected with the base plate via a soldering or welding connection. Soldering or welding connections, on the other hand, provide sufficient mechanical stability. On the other hand, sufficient sealing can also be provided with this connection.

More preferably, the connecting element has a peripheral recess at its end towards the pipe, into which the cured liquid silicone rubber extends. Along with this, a so-called shape-fitting connection between the liquid silicone rubber and the connecting element is provided. The connection between the pipe and the connecting element is better protected from corrosion.

Preferably, the connecting element has a protrusion, which extends into a space circumscribed by spirals. The protrusion can be formed as an integrated part of the connecting element or as a separate component, which is fixed to the base plate, for example. With this form, the end region of the pipe is lightened. The largest stresses in the individual pipes after the winding and connection with the connecting element, on the one hand, are manifested by mechanical deformation at the point of transition from the winding structure to the axial pipe ends, on the other hand at the soldering or welding positions in the base plate. Manifested by thermal loads. With the aid of the protrusions, the statically 'preloaded' areas of the pipe can be separated from the positions that can be loaded in the form of dynamic loads, for example by vibration, when mounted or in operation. In other words, by the projections, the risk of the pipe breaking is reduced.

In this case, the protrusion preferably has a length at least equal to the diameter of the spiral. To be more precise, the length corresponds at least to the inner diameter still exposed through the spirally guided pipes. With this length, the protrusions can develop a sufficient support function.

Preferably, the protrusion is conical at its end. That is, the projection is tapered toward its free end. This expands the radial spacing between the protrusion and the pipe toward the free end of the protrusion, thus giving some sort of flexibility in the region of the protrusion without too high stress loads appearing.

Preferably, a radial gap is provided between the protrusion and the pipe, which is filled with a cured liquid silicone rubber. This also improves the support function of the protrusions while maintaining the flexibility of the lines.

Alternatively or additionally to this, the connecting element may have a peripheral flange which projects towards the pipe, which surrounds the helix in the end region. That is, the flange forms a kind of 'cap' surrounding the end region of the fluid line. A radial gap can also be provided between the cap and the outer surface of the pipe, which is filled with liquid silicone rubber. In addition, a better protective action of the connection positions between the pipe and the connection element against action from the outside occurs.

Hereinafter, the present invention will be described through preferred embodiments with reference to the drawings.

1 is a schematic diagram of a fluid line with radially aligned pipe ends,

2 shows the fluid line according to FIG. 1 with one connecting element each at its end;

3 is a fluid line according to FIG. 2 after being embedded in liquid silicone rubber,

4 shows a modified embodiment of a pipe bundle with pipe ends axially aligned,

5 shows an axial cross section of the line according to FIG. 4 with a connection element, and a rigid embedding of plastic,

6 is a modified form with respect to FIG. 5, with a hollow space inside the liquid silicone rubber,

7 shows a modified embodiment of the line according to FIG. 5,

8 shows a second modification of the form according to FIG. 5,

9 shows a third modification of the form according to FIG. 5,

10 is a schematic view for explaining an injection molding facility;

11 are various procedural steps when producing a fluid line.

1 shows a helical pipe 1 of a fluid line 2. The spiral pipe 1 is provided with several, in this embodiment six pipes 3, each pipe 3 being wound along a helical line. At this time, all the pipes 3 are guided in parallel, so that the rising height of the helix corresponds to the sum of the diameters of the six pipes 3.

The pipe 3 has ends 4, 5, which protrude tangentially with respect to the helical pipe 1. In other words, the ends 4, 5 of the pipe 3 are parallel to the first plane and perpendicular to the second plane extending through the axis of the helical pipe 1. This results in a short installation length of the helical pipe 1 with the ends 4, 5. Instead of aligning the pipe end 3 in a completely tangential direction, it is also possible to bend the pipe end 3 at a different angle, for example parallel to the axis of the spiral pipe 1 if it is advantageous for a particular mounting situation. .

2 shows the helical pipe 1 before being placed in an injection molding tool. At both pipe ends 4, 5 a connecting element 6, 7 is arranged. These connecting elements 6, 7 can be connected with the ends 4, 5 of the pipe 3 in a suitable manner, for example by soldering, welding, gluing or other means.

The connecting elements 6, 7 are used to connect the openings 8 of the pipe ends 4, 5 to form one common fluid connection. For this purpose the connecting element 6 has an opening 9 and the connecting element 7 has an opening 10, which can later be used for connecting the fluid line 2 with other parts.

A core 11 is inserted into the spiral pipe 1 before being placed in the injection molding tool, the task of which is to empty the hollow space inside the spiral pipe 1 during injection molding. At this time, the core 11 is on all sides with respect to the helical pipe 1 It must have a gap, so that the pipe 3 of the helical pipe 1 can be completely covered with plastic.

3 shows the fluid line 2 after the injection molding process. The entire helical pipe 1 and the pipe ends 3, 4 are surrounded by a sheath 12 of cured liquid silicone rubber. The sheath 12 has extruded extensions 13, 14, which extend to the connecting elements 6, 7.

The core 11 is now removed out of the fluid line 2, so that the fluid line 2 has a cylindrical hollow space 15.

As liquid silicone rubber for the shell 12, for example, Dow Corning SILASTIC LSR, Wacker ELASTOSIL LR and GE-Bayer Silopren LSR can be used.

The use of liquid silicone rubber has the advantage that the shell 12 is highly elastic and resistant to high temperatures. Liquid silicone rubber is a two-component plastic. In this plastic, both components of low viscosity are cured when connected under heat absorption. If the spiral pipe 1 is heated and / or the injection molding mold is heated before inserting the spiral pipe 1 into the injection molding mold, the hardening process proceeds quickly in the injection molding mold so that a short cycle time can be realized. . At this time, curing can be achieved within a few seconds.

The low viscosity components of the liquid silicone rubber make it possible to supply a mixture of both components into the injection molding mold with a relatively low pressure of only a few bars. Correspondingly, the pipe 3, preferably made of metal, does not need to be supported from the inside. The pipes can be relatively thin walls without the risk of deformation of the pipes during injection molding.

As can be seen from FIG. 3, not only the pipe 3 but also the connecting elements 6, 7 fixed to the pipe 3 are embedded in plastic. Thereby, the seam at the connection between the pipe 3 and the connection elements 6, 7 is also reliably protected from corrosion attack.

4 shows a modified embodiment of the helical pipe 1, in which the end 3 is bent parallel to the axis of the helical pipe 1. Here, too, six pipes 3 are concerned. In the figure of FIG. 4, two pipes are placed on top of each other in the central area, so that only four end portions 4 of the pipe 3 can be seen in total.

The other end of the helical pipe 1 can be assembled in the same way as the end shown. However, it is also possible to form the other end of the helical pipe 1 as described, for example, with reference to FIG.

FIG. 5 shows the fluid line 2 with the spiral pipe 1 of FIG. 4 in a cut state. In order to recognize the pipe 3, the plastic of the shell 12 is shown so-called transparent.

There is one gap 16 between the pipes 3, which is likewise filled with liquid silicone rubber of the shell 12. In principle, the drawing of the finished line always relates to the cured liquid silicone rubber. If the fluid line 2 is exposed to vibration, the liquid silicone rubber resists friction between the pipes 3. In the form according to FIG. 5, no hollow space 15 is provided. Rather, the liquid silicone rubber not only surrounds the pipe 3 in the form of a sheath but also completely fills the interior.

The fluid line 2 has a modified form of the connecting element 17 with respect to the figures of FIGS. 2 and 3. The connecting element 17 has a base plate 18, which together with the housing element 19 surrounds the connecting space 20. The housing element 19 has an opening 21 towards the connecting space 20.

The base plate 18 has a through bore 22 for each end 4 of the pipe 3. The end 4 is guided through the through bore 22 and is connected with the base plate 18 with the aid of a brazing or welding seam 23. At this time, the soldering or welding seam 23 has two problems. The solder or weld seam mechanically secures the end 4 of the pipe 3 to the base plate 18. On the other hand the soldering or welding seam seals the connecting space 20 towards the spiral pipe 1.

Since the connection between the end 4 and the base plate 18 is made before producing the sheath 12 of liquid silicone rubber, the soldering or welding seam 23 is also made by the sheath 12 of liquid silicone rubber. Covered. At the same time, it is prevented that the soldering or welding seam 23 can be corroded by external influences.

6 shows a modified form of the fluid line 2. Identical elements are denoted by the same reference numerals. Here again the liquid silicone rubber of the shell 12 is again shown 'transparently', so that the pipe 3 can be seen.

Unlike the drawing according to FIG. 5, the hollow space 15 that was filled by the core 11 during the injection molding process is provided again. However, it can be seen that the pipe 3 is covered by a sheath 12 of liquid silicone rubber cured not only radially inside but also radially outside. Here too, a gap is provided between the pipes 3 and the cured liquid silicone rubber penetrates into this gap.

The housing element 19 has a peripheral recess 24 on the side facing the pipe 3. In practice, this recess 24 is arranged in the region of the base plate 18. If the housing element 19 extends beyond the base plate 18 in the direction of the pipe 3, the recess 24 may be provided elsewhere. The sheath 12 extends into the recess 24. Along with this, better sealing to the welding or soldering seam 23 is achieved.

FIG. 7 shows a form similar to that of FIG. 5. Therefore, like elements are denoted by like reference numerals. Here too, the shell 12 of the cured liquid silicone rubber is again shown transparent. The sheath completely fills the helical pipe 1.

The connecting element 17 has a projection 25, which extends into a spiral pipe 1 made of pipes 3 over a length corresponding to at least the inner diameter of the spiral pipe 1. The protrusion 25 can be integrally formed with the base plate 18 as shown. However, the protrusion may be formed as a separate part, which is fixed to the base plate 18.

The protrusion 25 has a radial gap 29 with respect to the pipe 3 over its entire circumference, which is again filled with a cured liquid silicone rubber.

The projection 25 has a conical taper 26 at its end, where the spacing to the pipe 3 is enlarged.

With this form, the end region of the helical pipe is lightened. The greatest stresses in the individual pipes 3 of metal arise after installing the end 4 on the winding and connecting element 17. Said stresses are, on the one hand, at the point of transition from the helical structure to the axial end 4, ie mainly by mechanical deformation. On the other hand, the stresses are exhibited at fixed positions of the pipe end 4 in the base plate 18, ie mainly by thermal loads.

With the aid of the projection 25, the statically 'preloaded' regions of the pipeline 2 can be separated from the positions that can be dynamically loaded in operation, in particular by vibration. This reduces the risk of broken lines.

The radial spacing 29 and the conical end 26 between the pipe 3 and the projection 25 allow some kind of flexibility of the line 2 even in the region of the projection 25 without exhibiting too high stress loads. .

FIG. 8 shows a modified form of the connecting element 17 with respect to FIG. 7. Parts that are the same and have the same function are indicated with the same reference numerals as in FIG. Here too, the sheath 12 of the cured liquid silicone rubber is again shown transparent.

The connecting element 17 has a peripheral flange 27, which surrounds the pipe 3 in its end region in the manner of a cap. The flange 27 has a diameter enlarged portion 28 at its open end. The flange 27 has a radial gap 29 with respect to the pipe 3 or the end 4 of the pipe. The sheath 12 extends into this gap 29.

The flange 27 also extends in the axial direction of the fluid line 2 over at least a length that matches the outer diameter of the helical pipe 1. The way of function is essentially the same as in the projection 25. In addition, a better protective action of the soldering or welding seam 23 occurs against the influence from the outside.

9 shows a combination of the features of the connecting elements of FIGS. 7 and 8. The connecting element 17 has a protrusion 25 as well as a peripheral flange 27. Due to this, the end 4 of the pipe 3 is better supported.

FIG. 10 schematically shows an injection molding facility 30 for embedding a spiral pipe 1 in a shell 12. Two components A and B are supplied to the mixer 33 from two storage vessels 31 and 32. The mixer 33 may be supplied with color 34 as necessary. The mixed components (A, B) are fed to the injection molding mold 36 via a line. Injection molding molds are also called injection molding tools. The injection molding die 36 has a connection 37, and a line 35 enters into this connection. This connecting part 37 is cooled. This prevents the mixture made of both components (A, B) from already increasing its viscosity and curing at the connection 37. In addition, the injection molding die 36 is preheated. Before being placed in, the helical pipe 1 can be heated to a temperature, for example in the range of 150 to 200 ° C. By heat supply to the mixed components of the liquid silicone rubber, very fast curing is achieved in the hollow space 38 of the injection molding mold 36. By cooling the connection 37, an injection molded article virtually without sprues can be produced in the form of a fluid line 2.

11 schematically shows individual procedure steps for producing a fluid line. The same elements as in FIGS. 1 to 10 are denoted by the same reference numerals.

The injection molding die 36 is opened (FIG. 11A). A spiral pipe 1 with connecting elements 4, 5 and optionally a core 11 is arranged in the injection molding die 36, and the injection molding die 36 is closed (FIG. 11B). Then, the liquid silicone rubber 39 is supplied through the line 35 and the cooled connection 37 (FIG. 11C). As soon as the hollow space 38 is filled (FIG. 11D), by heat supply and / or over time, it is safe for the liquid silicone rubber 39 to cure. As soon as the liquid silicone rubber 39 is cured, the injection molding mold 36 is opened and the completed fluid line 2 can be taken out (FIG. 11E). In some cases, the core 11 must be removed. The fluid line 2 can be withdrawn virtually without sprues.

Claims (21)

Several pipes 3 are respectively wound in parallel along spirals, at least one end 4, 5 with fastening elements 6, 7; 17, with pipe 3 embedded in plastic, A method for producing a fluid line (2), wherein a liquid silicone rubber (12) is used as the plastic. The method of producing a fluid line according to claim 1, wherein the liquid silicone rubber (12) is applied on the pipe (3) in an injection molding method. 3. The pipe (3) according to claim 2, wherein the pipe (3) is arranged in an injection molding mold (36), and the component mixture of the liquid silicone rubber (12) is introduced into the injection molding mold (36) through a cooled inlet channel (37). Method for producing a fluid line, characterized in that. 4. A method according to claim 3, characterized in that the pipe (3) is heated before being placed in the injection molding die (36). Method according to claim 3 or 4, characterized in that the injection molding die (36) is heated. A fluid line 2 having several pipes 3, each guided and parallel along a spiral, said pipes having one common connecting element 6, 7; 17 at at least one end 4, 5; Wherein the pipe (3) is a fluid line (2) embedded in the plastic, said plastic being a cured liquid silicone rubber (12). 7. Fluid line according to claim 6, characterized in that the cured liquid silicone rubber (12) covers the connection arrangement (23) between the pipe (3) and the connection element (17). 8. A fluid line according to claim 6 or 7, wherein the pipes (3) have a spacing (16) from each other, in which a cured liquid silicone rubber (12) is arranged. 9. The fluid line according to any one of claims 6 to 8, wherein the cured liquid silicone rubber 12 surrounds the hollow space 15 inside an interior space surrounded by a pipe 3. . 10. Fluid line according to any of the claims 6 to 9, characterized in that the connecting element (6, 7) is arranged outside of the longitudinal axis of the helix. 11. Fluid line according to claim 10, characterized in that the ends (4, 5) of the pipe (3) protrude tangentially with respect to the helix. 10. Fluid line according to any of the claims 6 to 9, characterized in that the end (4) of the pipe (3) is bent parallel to the longitudinal axis of the helix. 8. The connecting element (17) according to claim 6 or 7, wherein the connecting element (17) has a base plate (18) with through openings (22) in which the end (4) of the pipe (3) is inserted into the through openings. Fluid line, characterized in that. 14. Fluid line according to claim 13, characterized in that the base plate (18) defines a connecting space (20) together with a housing element (19), wherein the housing element (19) has an opening (21). . 15. Fluid line according to claim 13 or 14, characterized in that the end (4) of the pipe (3) is connected with the base plate (18) via a soldering or welding connection (23). The liquid silicone rubber according to any one of claims 6 to 15, wherein the connecting element (17) has a peripheral recess (24) at its end facing the pipe (3) and cured into the recess. Fluid line, characterized in that (12) is extended. 17. The connection element 17 according to any one of claims 6 to 16, wherein the connecting element 17 has a projection 25, which projection is circumscribed by a spiral. A fluid line extending into the space. 18. The fluid line of claim 17, wherein the protrusions have a length that is at least equal to the diameter of the helix. 19. Fluid line according to claim 17 or 18, characterized in that the protrusions (25) are conically shaped at their ends (26). 20. A radial gap 29 is provided between the protrusions 25 and the pipe 3, the radial gap being filled with a cured liquid silicone rubber 12. There is a fluid line. 21. The connecting element (17) according to any one of claims 6 to 20, characterized in that the connecting element (17) has a peripheral flange (27) projecting towards the pipe (3), which flange surrounds the helix in the end region. Fluid lines.

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