GB2279422A

GB2279422A - A corrugated pipe made of thermoplastics material

Info

Publication number: GB2279422A
Application number: GB9410338A
Authority: GB
Inventors: Bernd Kleinhens; Stephan Mann; Janos Kertesz
Original assignee: Rasmussen GmbH
Current assignee: Norma Germany GmbH
Priority date: 1993-06-30
Filing date: 1994-05-24
Publication date: 1995-01-04
Also published as: DE4321575C1; FR2708326A1; GB9410338D0; JPH0771663A

Description

2279422 1 A CORRUGATED PIPE MADE OF THERMOPLASTICS MATERIAL The invention

relates to a corrugated pipe made of thermoplastics material for use as a fluid conduit in a motor vehicle.

With a corrugated pipe disclosed in Patent Specification DE 36 10 176 C2, the peaks and troughs of the corrugations extend around the entire periphery of the pipe, symmetrically about the central longitudinal axis of the pipe. With this arrangement, after the corrugated pipe has been laid, liquid, in particular condensation water in the case of a breather tube for the crank-case of a combustion engine in a motor vehicle, which is conducted through the corrugated pipe will collect on the inside of the corrugated pipe in the regions at the bottom of the inner corrugation troughs. If the temperature in the corrugated pipe is low enough, the liquid can freeze and result in the corrugated pipe becoming blocked. or the ice can break and fall back into the crankshaft housing.

The present invention is concerned with reducing the risk of liquid collecting in such a pipe.

In accordance with the present invention, the corrugations, at least in one longitudinal region of the corrugated pipe which has a bottom wall portion in the fitted condition, are eccentrical in such a way that the inside of this wall portion is free of corrugations. With this design of corrugated pipe. there are no corrugations in the bottom wall portio in which liquid can collect and freeze. The risk of blockage resulting from this and the risk of broken pieces of ice entering sensitive regions is therefore largely avoided. Nonetheless, the corrugated pipe is still slightly flexible in an axial plane extending in the longitudinal direction of the corrugated pipe through the corrugation- free wall portions. 30 Preferably, the corrugated pipe is circular in cross-section in each place. Therefore, in the corrugation- free wall portion, there is a greater resistance to bending transversely to the afore-mentioned axial plane which reduces bending due to vibration after the pipe has been laid, e.g. in a motor vehicle, transversely to this axial plane, so that when the corrugated pipe is laid in a restricted space, any oscillation of the corrugated pipe due to vibration transversely to the afore-mentioned axial plane can. anyway, result in the corrugated pipe 2 being deflected laterally to a limited extent, and noise can be prevented which would occur if the sides of the corrugated pipe hit the walls delimiting the space.

Preferably, the afore-mentioned bottom wall portion is smooth on the inside and outside. This overcomes the problem of resistance to flow on the inside and also the excessive amount of material used because of ribs forming radially outer corrugation peaks.

Preferably, the afore-mentioned longitudinal region is a region of curvature. Admittedly, it is possible to design the entire corrugated pipe, if it extends in a straight line horizontally or on a slant, or to design only a straight slanted longitudinal region, so that it is free of corrugations on the inside. However, it is also advantageous, during laying, to design the regions of the corrugated pipe which are to be bent so that they are free of corrugations on the inside in their bottom wall portion. The risk of liquid collecting would then be reduced in these longitudinal regions.

A specific embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:

Figure 1 is a side view of a corrugated pipe according to the invention; Figure 2 is a section taken on line II-II of Figure 1; Figure 3 is the section taken on line III-III of Figure 1; Figure 4 is a vertical axial section through the end region of the corrugated pipe, to the right of Figure 1; Figure 5 is an illustration of the corrugated pipe of Figure 1 with bent longitudinal regions; and Figure 6 is the view of the corrugated pipe shown in Figure 5. viewed from the right in Figure 5.

The corrugated pipe shown in Figures 1 to 6 has two outer longitudinal regions 1 and 2 which extend to near the ends of the corrugated pipe and also a central longitudinal region 3. All longitudinal regions 1 to 3 are provided with corrugations 4, 5 and 6 which are merely shown by onedimensional lines in Figures 5 and 6 for the sake of simplicity. The corrugations 4 and 5 of the longitudinal sections 1 and 2 are designed eccentrically in such a way that the wall portions 7 and 8 which are disposed to the bottom when the corrugated 3 pipe is in the fitted condition are free of corrugations on the insides 9 and 10. On the other hand, the corrugations 6 of the central longitudinal section 3 extend radially symmetrically to its central longitudinal axis over its entire periphery.

Therefore, the corrugated pipe is of circular cross-section over its entire length in every place.

However, the end regions 11 and 12 directly adjoining the ends are completely free of corrugations.

In the fitted condition, e.g. in a motor vehicle of restricted space, the central longitudinal region 3 is laid vertically, whilst the longitudinal regions 1 and 2 form regions of curvature, wherein they are curved in such a way, or extend in such a way, that their wall portions 7 and 8 which are free of corrugations are disposed on the underside. as shown, for example. in Figures 5 and 6. Therein. the longitudinal regions 1 and 2 extend in respective vertical planes.

With the corrugated pipe shown. in the fitted condition, no liquid can collect in the longitudinal regions 1 and 2 since the bottom wall portions 7 and 8 in the fitted condition of Figures 5 and 6 are free of corrugations. Nonetheless. the longitudinal regions 1 and 2 of the pipe are flexible in the axial planes passing through the wall portions 7 and 8, so that it can be bent into the desired shape when it is laid. On the other hand, it is less flexible transversely to that axial plane in the longitudinal regions 1 and 2 due to the circularly cylindrical cross-sectional shape, and so oscillation of the corrugated pipe transversely to these axial planes due to vibration is largely avoided.

The corrugated pipe is made of thermoplastics material. particularly polyamide or a thermoplastics elastomer.

Also, in the case of corrugated pipes which are intended to be laid horizontally or on a slant, it is favourable if a bottom wall portion which passes over the entire length, such as the wall portion 8, is free of corrugations.

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Claims

1. A corrugated pipe made of thermoplastics material for use as a fluid conduit in a motor vehicle. the corrugations, at least in one longitudinal region of the corrugated pipe which has a bottom wall portion in the fitted condition, being eccentrical in such a way that the inside of this wall portion is free of corrugations.

2. A corrugated pipe according to claim 1, which in each place is circular in cross-section.

3. A corrugated pipe according to any one of claims 1 or 2, wherein the wall portion is smooth on the inside and outside.

4. A corrugated pipe according to any one of claims 1 to 3, wherein the longitudinal region is a region of curvature.

5. A corrugated pipe which along at least part of its length is free of corrugations on its underside.

6. A corrugated pipe substantially as hereinbefore described with reference to the accompanying drawings.

7. A motor vehicle having a fluid conduit provided by a pipe as claimed in any preceding claim, said wall portion being on the underside of the pipe.

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