FR2849148A3 - Reinforced flexible garden hose comprises knitted fabric forming rows of stitches with axis parallel to hose axis with threads progressively displaced diagonally in opposite directions - Google Patents

Abstract

The reinforced hose comprises a knitted fabric (3) forming rows of stitches (3A) with their axis (P) parallel to the hose longitudinal axis (R). The threads (8,9) are progressively displaced diagonally in opposite directions (U,W) relative to the hoses axis.

Description

SOFT PIPE ARM

  The invention relates to an armed hose.

  The pipes intended for watering gardens or lawns are made of a plastic material such as polyvinyl chloride or "PVC".

  In order to improve their resistance, in particular to the pressure, it is known to integrate in the thickness of their wall a reinforcement.

  This reinforcement makes it possible to reduce the thickness of the tube in order to give it flexibility.

  However, the presence of this frame generates difficulties.

  A first disadvantage may come from the manufacturing process which is a little more complex than the manufacture of a simple extruded pipe, but the advantages provided largely offset the disadvantages.

  In fact, to manufacture these armed pipes, we begin by making a first pipe on which is made a reinforcement gradually extrusion of the first pipe.

  Then, this inner pipe coated with its frame receives a protective layer which fixes the frame and protects it from external mechanical aggression.

  This frame should not be elastic in that it must prevent the expansion of the pipe or at least contain it.

  To achieve this reinforcement, it is known to helically wound a wire around the inner pipe.

  This process also called "wrapping" increases the stiffness of the pipe.

  Due to the reduction in thickness, the pipe is softer than before but when the reinforcement is added, it loses flexibility.

  Instead of this wire wound in a helix, it is known to use a knit.

  The realization of these knits is done by means of circular knitting machine.

  Due to the progressive advance of the pipe, the meshes are inclined with respect to the longitudinal axis of the pipe.

  For this reason, when the hose is pressurized, the knit becomes taut and the forces developed in this knit tend to cause twisting or kinking of the hose which pinches.

  To minimize this phenomenon, a reinforced pipe (EP-A-0 623 776) 5 is known according to which the axis of the knit is inclined so that the orientation of the warp yarns forms with the longitudinal axis of the pipe a value angle. absolute equal to that formed between the axis of the weft son and the longitudinal axis but of opposite sign.

  The settings are difficult because we must take into account the mesh geometry.

  A second principle (FR-A-2 793 866) is also known which consists in depositing two knits, one above the other, the knits being in the opposite direction.

  This product works as well as the previous one.

  However, it deplores an extra thickness and twisting effects because it is difficult to control the positioning of one knit relative to another.

  The invention proposes to provide a new technical solution.

  To this end, the subject of the invention is a hose comprising a knit and means limiting the torsion of the hose under the effect of the internal pressure, this knit being characterized in that the knit is a knit with gathered stitches forming rows of stitches whose symmetry axis of the stitches is parallel to the longitudinal axis of the pipe with, however, the yarns progressively moving diagonally in opposite directions with respect to the longitudinal axis of said pipe.

  The invention will be better understood using the following description given by way of non-limiting example with reference to the accompanying drawing which schematically shows a pipe being developed.

  Referring to the drawing, there is seen a reinforced pipe 1 of a knit being made.

  This pipe comprises an inner tube 2 covered with a knit 3 itself covered with a protective layer 4, this protective layer also having the function of fixing the knit 3 on the inner tube.

  In order to avoid that, under the effect of the pressure of the fluid passing through the pipe, the latter is twisted, the pipe comprises means limiting the torsion.

  According to the invention, the knit 3 is a knit 3 with gathered stitches forming rows 3A of stitches whose axis P of the stitches, said to be symmetrical, is parallel to the longitudinal axis R of the pipe, but with the strands 8, 9 moving progressively diagonally in directions U, W opposite to the longitudinal axis of said pipe. Thus in this form, the knit is formed of groups 10, 11 of identical stitches moving in the direction of a first helix and groups of stitches which are equally identical, moving in the direction of a second helix in the opposite direction to the first helix, which cancels the effects.

  If you look at a 3-row row of stitches, one stitch of one group alternates with another stitch of another group.

  There is therefore a symmetry between two meshes which are side by side; these meshes will be of the same size.

  Moreover, the forces induced by the bonding zones 13 between two meshes of the same group which are inclined with respect to the longitudinal axis are compensated by the forces induced by the bonding zones 14 of a group going into the 'other way.

  We obtain a distribution of meshes of the type comparable to a checkerboard so that the torsion forces cancel each other out.

  We therefore have a homogeneous distribution regardless of the width and / or the height of the mesh.

  By playing on the size of the mesh, one can obtain a more or less flexible pipe.

Claims (1)

  1 reinforced flexible hose comprising a knit and means limiting the torsion 5 under the effect of the internal pressure CHARACTERIZED in that the knit (3) is a knit (3) with gathered stitches forming rows (3 A) of stitches of which the axis (P) of the meshes, said to be symmetrical, is parallel to the longitudinal axis (R) of the pipe, with the wires (8, 9) moving progressively diagonally in opposite directions (U, W) relative to to the longitudinal axis of said pipe.