FR2725260A1 - HOSE FOR TRANSPORTING FLUID - Google Patents

Abstract

A vehicle fuel pipe includes inner, middle, and outer tubular concentric layers (5, 6, 8). The inner and outer layers (5, 8) are made of rubber providing good resistance to temperature and to shocks or mechanical stresses. The intermediate layer (6) is substantially thinner than the inner and outer layers, its thickness is for example 0.1 to 1 millimeter; it is substantially impermeable to fuel. The rubber layers provide the necessary resistance to temperature and mechanical stresses, but do not need to have good fuel impermeability.

Description

The invention relates to pipes for transporting fluid. Of

  pipes according to the invention and which will be described in more detail below with reference to an example, are fuel pipes for use in motor vehicles. According to the invention, there is provided a pipe comprising a wall having a plurality of concentric tubular layers, an intermediate layer between the inner and outer layers, which is substantially more impermeable to the fluids to be transported by the pipe, than at least one other layers, and at least one of the other layers providing higher resistance to temperature and impact

  mechanical than the intermediate layer.

  According to the invention, there is further provided a pipe for transporting fuel in a vehicle, comprising a wall having three concentric tubular layers, the inner layer being made of non-cellular rubber having a high temperature resistance, the intermediate layer being made of plastic and substantially impermeable to fuel, and the outer layer being made of a cellular elastomeric material and

  appreciably resistant to impact or mechanical stress.

  A fuel hose according to the invention for use in motor vehicles will be described in the following by way of example and with reference to the attached drawing which represents a perspective view on the

half of a pipe in section.

  As we see in the figure, the pipe consists of three layers

circumferential.

  The inner layer 5 is made of a compact elastomeric material. The intermediate layer 6 has the shape of a thin layer, or of a skin, of a plastic material such as polyamide; its thickness is

  preferably between 0.1 and 1 millimeter.

  The outer layer 8 is made of an elastomeric material either

full, either foam.

  The intermediate layer 6 made of polyamide or a similar plastic material has very low permeability. Its permeability

  vis-à-vis the fuel is for example of the order of 1 gram per hour.

  It is relatively inexpensive and much less expensive than

  rubber material with the same degree of permeability.

  The inner and outer rubber layers protect the thin intermediate layer 6 of plastic. In particular, they provide the necessary capacity to withstand a relatively wide temperature range and to exhibit high mechanical strength. A pipe made only of polyamide or a similar plastic material would not have the necessary resistance to temperature and

mechanical stress.

  In this way, a pipe is therefore produced which satisfies the requirements economically and efficiently ("specifications")

  specified by vehicle manufacturers.

  Thus, it is possible to use kinds of rubber already accepted by vehicle manufacturers for use in other applications in vehicles, for fuel hoses, the low permeability necessary for fuel being ensured by using the intermediate material.

  polyamide or similar plastic.

  The pipe can take the desired configuration (having one or more predetermined bends) in different ways. For example, the pipe can be heated to soften the thermoplastic material of layer 6 and then be forced to take the desired configuration by means of a mold. When the thermoplastic material cools, the desired configuration of the pipe is maintained. This operation, which is carried out after vulcanization of the rubber layers, requires that the thermoplastic layer be relatively thick, for example of the order of 0.8 to 1 mm. In another example, the pipe is placed on a bar before vulcanization of the rubber, the bar having the desired final configuration of the pipe. The pipe mounted on the bar is then subjected to an appropriate treatment to vulcanize the rubber layers which maintain the pipe in the desired configuration after removal of

bar.

Claims (7)

Claims   1. Pipe comprising a wall having a plurality of concentric tubular layers (5, 6, 8), these layers (5, 6, 8) being constituted by a layer (6) intermediate between an inner layer (5) and an outer layer (8), the intermediate layer being substantially more impermeable to the fluids to be transported by the pipe than at least one of the other layers (5, 8), and at least one of the other layers (5, 8) providing resistance higher at temperature and mechanical shock than the intermediate layer (6), characterized in that said inner layer   (5) is made of an elastomeric material or rubber.   2. Pipe according to claim 1, characterized in that the layer   intermediate (6) is made of plastic.   3. Pipe according to claim 2, characterized in that the material plastic is polyamide.   4. Pipe according to any one of the preceding claims,   characterized in that the thickness of the intermediate layer (6) is from about 0.1 to 1 millimeter.   5. Pipe according to any one of the preceding claims,   characterized in that the outer layer (8) is also made of   elastomeric or rubber material.   6. Pipe according to claim 5, characterized in that the inner layer (5) consists of a solid elastomeric material (non-cellular).   7. Pipe according to either of Claims 5 and 6, characterized in that   that the outer layer (8) is made of a cellular elastomeric material.