FLEXIBLE HOSE

Abstract: Flexible hose-pipes are disclosed which comprise a flexi­ ble plastics material tube, preferably a rigid plastics material such as polytetrafluoroethylene, polypropylene, polyamide or unplasticised polyvinylchloride, wound helically with a rein­ forcing wire. The wire has a cross-section such that its thick­ ness in the radial direction at any point on the tube exceeds the thickness in the axial direction and the wire is not adhered to and does not form part of the tube. Hose-pipes constructed in this manner exhibit superior crush-resistant properties to hose-pipes of a similar weight of conventional construction.

Description: FLEXIBLE HOSE This invention relates to improved flexible hose and in particular relates to a flexible hos having improved resistance to crushing Reinforced flexible hosepipes in general comprise a plastics material or rubber tube reinforced with internal or external helically wound wire Such a hose is flexible and able to withstand high internal pressures, and furthermore has a degree of crush resistance afforded by the reinforcing wire However, if it is desired to increase the crush resistance for certain applications then hitherto it has been the practice to use a heavier. gauge wire reinforcement or space the helical wire windings closet together, Both of these solutions increase the weight of the hose and generally lower its flexibility. The invention seeks to provide a reinforced plastics material or rubber hose of high resistance to crushing which does not suffer from the above drawbacks. According to the present invention there is provided a hose which comprises a flexible tube wound helically with a reinforcing profiledstrip, the strip having a cross-section such that the second moment of area of the corss-section with respect to a neutral axis, substantially parallel to the longitudinal axis of the convoluted tube, is greater than the second moment of area with respect to any other neutral axis of the cross-section, and the strip not forming part of or being adhered to the flexible tube. Preferably, the tube will be a plastics material or a rubber tube but may be of other materials, for example, thin metal. Furthermore, the tube should be a convoluted tube having helical cpnvolutions which in use receive the helical wire windings. The hoses to which the invention relates are helically convoluted hoses, that is hollow tubes which have been formed with helical contours on the outside surfaces and corresponding helical contours on the inside surfaces such that the tube wall will appear, in longitudinal section, to have a regular undulating wave form. This wave form may be, for example, sine wave form, saw-tooth wave or square wave. Furthermore, the helical convolutions may originate from a single point or more than one point. The profiled strip may be, for example, of a tough resilient plastics material but is preferably of a metal, such as steel, and may be a steel wire. The helical windings of a tube according to the invention may be internally of the tube or externally, preferably the latter, or both. Furthermore, the windings of wire having a cross-section according to the invention may be employed either alone or together with further windings of wire having a conventional cross-section. The tube of the hose of the invention is preferably made from a relatively rigid plastics material such as polytetrafluoroethylene, polypropylene, polyamide, unplasticised polyzirlylchloride, and the like materials, although plastics lass rigid in nature such as plasticised polyvinylchloride may be used. Bonding the helical reinforcing profiled strips of the invention to or within the tube should be avoided; nor need the tube be held entrapped between internal and external wires as with conventional rubber and flexible plastics hose. The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view, in half section of a hose-pipe constructed accordin(g to the invention; Figure 2 is a similar view to Figure 1 of another embodiment of the invention; Figure 3 is a similar view to Figure 1 of a third embodiment of the invention; Figure 4 is a partial view of a fourth embodiment of the invention; and Figures 5a and b are cross-sections of reinforcing wires suitable for use in the hose of the invention. Referring to the drawings, a length of hose-pipe according to the invention is shown in Figure 1 in which a convoluted plastics material tube 10 has conventional round section internal reinforcing wire 12 within its internal convolution. An external helically wound profiled strip, in this case a reinforcing wire 14, has a cross-section illustrated in Figure 5a, that is the thickness of te wire in the radial direction is greater than the thickness of the wire in the axial direction. In Figure 2 it can be seen that the profiled strip reinforcing wire 14 according to the invention is internally of the tube PO and conventional reinforcing wire 12 is located externally. Figure 3 illustrates a hose with outer reinforcement for example braiding 16. The reinforcing wire according to the invention 14 is externally of the tube 10. In Figure 4 the profiled strip of the invention 14 is held in position by the shape of the helically convoluted tube section 10 and this allows a wider spacing between successive windings of the strip 14 thus enabling a lightweight crush resistant hose to be made. Figures 5a and b illustrate preferred crosssections of the profiled strip 14. The dimension Y will, in use in a hose,-be generally in the axial direction, and the dimension X will be generally in the radial direction. To obtain the benefits of the invention, the dimension X should in general be greater than the dimension Y This ensures that the second moment of area of the cross-section with respect to the transverse axis A-A (Figure 5a) or B-B (Figure Sb) passing through the centre of gravity is greater than the second moment of area with respect to any other axis. Axis A-A or B-B is, of course, substantially parallel to the longitudinal axis of the convoluted tube. In Figure 5b a modified cross-section of the wire 14 is shown in which rounded ends and radiused corners are provided so as to prevent or reduce damage to the tube 10 either during manufacture thereof or during service after manufacture. A hose constructed according to the invention has superior crush resistance properties when compared with a hose of the same weight constructed in the conventional manner. It has been found that the crush resistance can be increased by a factor of two or more in accordance with the invention. Furthermore, the ease of flexing the finished produce to a specific radius is improved in comparison with a similar hose of the same weight employing conventional round section wire reinforcement. A hose in accordance with the invention may, for example, be run over by a loaded bulk liquid road tanker and it would not only resist damage but will not be cracked or flattened. Thus there will be no interruption to the flow of liquid within the hose.

Claims: CLAIMS: 1. A flexible hose which comprises a flexible helically convoluted tube wound helically with a reinforcing profiled strip, the strip having a crosssection such that the second moment of area of the cross-section with respect to a neutral axis, substantially parallel to the longitudinal axis of the convoluted tube, is greater than the second moment of area with respect to any other neutral axis of the cross-section, and the strip not forming part of or being adhered to the flexible tube. 2. A flexible hose as claimed in claim 1 in which the tube is made of a plastics material. 3. A tube as claimed in either of claims 1 or 2 in which the helical windings are externally of thetabe. 4. A flexible hose as claimed in any one of claims 1 to 5 in which the helical windings are internally of the tube. 5. A flexible hose as claimed in any one of claims 1 to 4 in which the tube is made from a relatively rigid plastics material. 6. ¯A flexible hose as claimed in claim 5 in which the plastics material is polytetrafluoroethylene, polypropylene, polyamide or unplasticised polyvinylchloride. 7. A flexible hose as claimed in any one of claims 1 to 6 in which the strip is provided with rounded ends and radiussed corners to prevent and reduce damage to the tube during manufacture or during service. 8. A flexible hose as claimed in any of claims 1 to 7 in which the strip is a steel wire. 9. A flexible hose as claimed in any of claims 1 to 8 in which thickness of the strip in the radial direction at any point on the tube exceeds the thickness in the axial direction.

Inventors: WHITWORTH, BARRIE FINBARR
Applicants: STANDARD HOSE LIMITED
Application year: 1981
Main classification: F16L11
IPC codes: F16L11