Flexible hose with external sheathed electrical conductor

DETAILED DESCRIPTION The invention provides a helically fabricated electrically conductive flexible hose which includes at least one plastic strip wrapped helically with successive convolutions overlapping to form a flexible hose wall of at least one ply.
At least one self-supporting electrically conductive helical reinforcing element forms the outermost element of the hose and is concentric with and engages the outside of the wall.
This element is of composite construction comprising at least two spaced inner metal wires and an outer plastic sheath of non-circular cross-section enclosing the wires and having a substantially flat side facing inwardly and engaging the outer ply of the wall.
The plastic sheath is bonded to the plastic wall.
In a preferred form of the invention a separate plastic insulation layer surrounds each metal wire within the plastic sheath.
The external profile of the hose of the invention is sharply defined by the convolutions of the helical reinforcing element and the wall is otherwise light in weight and very flexible.
By using a continuously advancing mandrel such as that disclosed in U.
S.
Pat.
No.
3,155,559, the hose structure can be produced quickly with an easy machine setup and very little machine down time.
The other convoluted sheath about the conductors also serves as a scuff strip which improves the abrasion resistance of the hose while the bore of the hose is notably smooth to provide good air flow properties.
Other advantages of the invention will become apparent in the following description of a preferred embodiment in conjunction with the accompanying drawings.