DE2453238A1 - FUEL PIPE FROM PLASTIC PIPE - Google Patents

Description

10/23/197 ^ Pf / Kb

Attachment to

Patent and

Utility model registration

Robert Bosch GmbH, 7 Stuttgart 1 Plastic pipe fuel line

The invention relates to plastic pipe fuel lines.

Up to now, fuel lines have mainly been made of metals. For some time, however, there has been a move towards manufacturing these lines from plastic pipes ₃ because they are lighter, more flexible and therefore easier to assemble. As plastics come for this

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especially polyamides. In DIN 73378 is already a standard for such pipes made of polyamide for motor vehicles, which takes this area of use into account wearing.

However, to date, one problem has not been addressed either in the aforementioned DIN or in other literature: Tests have shown that the lines made of plastic, as they are used today, in the event of a fire leak after a short time and a loss of pressure occurs in these lines. This is a disadvantage the fuel lines made of plastic pipes, since such a short time is not enough to possibly to extinguish any fire that occurs. However, if the fire can be extinguished, the system is no longer in working order, apart from the fact that by adding more fuel there is a risk that the The fire continues to spread, causing further damage to the units.

The object of the present invention is therefore to provide fuel lines made of plastic pipe that remain tight in the event of a fire at least until a fire occurs Fire is normally extinguished. Under normal circumstances, this time is approx. 5 minutes. When using such Damage to the assemblies beyond what is necessary is prevented The consequences of fire are kept to a minimum - which is generally used for safety - and there is more than that some likelihood that the aggregates will be kept functional.

This object is achieved according to the invention in that the plastic pipe serving as a fuel line is on its

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outer surface a protective layer of a flame retardant Fabric wears.

The term "flame-retardant" is to be understood here as meaning those substances that have good thermal insulation Prevent a too rapid leakage or even an ignition of the fuel pipe and that of its own accord may also be difficult to burn. These are, for example, substances that are exposed to flames produce a foam that has a heat-insulating effect due to its porous structure and thus prevents the Inner pipe temperature rises too quickly. In addition, the protective layer should by a certain amount Strength delay the bursting of the plastic pipe, which is under internal pressure and softening in the heat.

The following protective layers can be considered: thermoplastic or thermosetting plastics materials as well Lacquers, whereby these substances can optionally contain a propellant, so that a porous, an even better heat-insulating protective layer is created; also elastomers. In the case of heat-softening, propellant-free Protective layers, it is advantageous to use flexible reinforcement to delay the bursting of the fuel pipe or to prevent. - PVC has proven particularly useful as a thermoplastic material, while the thermosetting plastic compounds, for example based on epoxy resin. PVC lacquer, a lacquer paint with a high metal content, is particularly popular among the paints as well as a varnish that is a mixture and / or copolymer made of PVC and polyacrylic acid ester and contains a blowing agent, into consideration. As elastomers have / for example Silicone rubber and chloroprene rubber have proven their worth. - The flexible reinforcements can be made of, for example

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Metal hose ^ wire mesh or made of glass or asbestos fabric exist. They can advantageously be used in conjunction with the blowing agent-free thermoplastic Plastic compounds and lacquers as well as used with the elastomers will.

The blowing agent-containing protective layers have the advantage ₅ that to be applied protective layer can be kept thin, namely Oj5 since foamed to 3 mm ₃ in case of fire, this layer is many times _s so that a sufficient thermal insulation and compressive strength is ensured.

The protective layers can be applied to the plastic pipe in various ways. The thermoplastic Plastic compounds are particularly beneficial with the help of the extrusion process around the plastic pipe. The thermosetting plastic masses are for example applied by electrostatic powder coating or whirl sintering. The paints can through Brushing, spraying or dipping can be applied.

The invention is to be explained in more detail below.

In the figures, possibilities of the structure of the fuel line according to the invention are shown by way of example, in each case in section.

Show it:

1 shows a fuel line with an externally applied layer of lacquer prior to exposure to fire, _{see FIG}

Fig. 2 shows the same line after exposure to fire, Pig. 3 and 4 fuel lines with coatings

Soft rubber and a reinforcement.

In Fig. 1, the fuel-carrying plastic pipe is 1 designated. The protective layer denoted by 2 consists

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2Ä t9

from a mixture and / or copolymer of PVC and Polyacrylic acid ester with a propellant component. The thickness of the layer is 1 mm. She is going through Diving applied.

FIG. 2 shows the line according to FIG. 1 after a fire, with the protective layer designated by 3 has enlarged many times and is porous.

Fig. 3 shows the possibility of the pipe 1 initially with a To cover soft rubber hose 4 made of silicone rubber or chloroprene rubber and on this soft rubber hose a apply flexible reinforcement 5 made of wire mesh. The soft rubber hose 4 prevents due to its Flammability, so that the flame reaches the fuel-carrying plastic pipe too quickly. Basically already leads an embodiment of the invention Success without the flexible reinforcement, but there is a risk that the plastic pipe due to the action of heat from the outside and the hydrostatic pressure of the fuel bursts from the inside because the rubber hose is too soft and gives way. To prevent this from happening, use the rubber hose

4 nor the reinforcement 5 made of wire mesh, so

that the hose 4 can not give way. The reinforcement 5 can however, as shown in FIG. 4, they also lie between the plastic pipe 1 and the hose 4. The usage a metal mesh as the material for the reinforcement

5 is particularly advantageous because the metal, due to its high thermal conductivity, affects the plastic pipe 1 can dissipate incoming heat quickly at points of lower temperature and thus also contribute to that the plastic pipe 1 is not damaged too quickly.

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The testing of the fuel lines was done in the following way: One flat sheet metal pan is on three Sides surrounded by approx. 50 cm high sheet metal walls. By Two holes in two opposing sheet metal walls 24 cm above the sheet metal pan will be the fuel line to be examined The line is under a pressure of 2.5 at in a fuel circuit, the specified fuel pressure is maintained with the aid of a pump and a pressure regulator. The pressure can be read on a pressure gauge located in the circuit. When the pressure in the fuel line has built up, the Sheet metal pan filled with normal fuel and ignited so that the fuel line is surrounded by flames. Measured is the time that passes before the line starts to leak, which can be seen from the fact that initially more or more fuel is used fewer fine holes are sprayed in the pipe. A short time afterwards, there is a drop in pressure, which can be read on the pressure gauge. because the line eventually bursts. This is the course of all experiments in which plastic pipes without one Protective cover were used. The pipes are made of polyamide PAIl or PA12 and had a diameter of 8 mm and a wall thickness of 2 mm.

The fuel lines according to the invention, which have a flame-retardant Wore protective coating, showed at least three times better stability, i.e. they were during the The duration of the experiment neither leaked nor a loss of pressure.

It follows that with the fuel lines according to the invention unites a significant improvement in fire safety. Due to the longer service life a larger fuel supply is no longer recorded in the event of a fire.

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Claims (10)

<& A 1 Expectations !., Fuel line made of plastic pipe, characterized that the pipe carries a protective layer of a flame retardant material on its outer surface. 2. Fuel line according to claim 1, characterized in that the protective layer consists of a thermoplastic plastic compound consists. 3. Fuel line according to claim 1, characterized in that that the protective layer consists of a thermosetting plastic compound. 4. Fuel line according to claim 1, characterized in that the protective layer consists of a lacquer. 5. Fuel line according to one of claims 2 to 4, characterized in that the protective layer is a propellant contains. 6. A method for applying a protective layer made of a thermoplastic plastic compound according to one of claims 2 or 5> characterized in that the plastic pipe is overmolded by extrusion coating with the plastic compound. -8th- 60 98 2 1 / OA22 2 A 1 7 "Fuel line according to claim 5 _S, characterized in that the thickness of the protective coating is between O ₅ 5 and 3 mm. 8. Fuel pipe according to claim I ₃ characterized _s that the protective layer of a flame retardant elastomer such as silicone rubber or chloroprene rubber is. 9. fuel pipe according to any one of claims 2 _S 4 or 8 characterized in that _{a s} that the protective layer bearing a flexible reinforcement of metal tube or wire ₃ glass or asbestos braid " 10. Fuel line according to one of claims 2 _S 4 or 8 _5, characterized in that it carries a flexible reinforcement made of metal hose or wire ₉ glass or asbestos mesh between the plastic pipe and the protective layer » 609821/042