CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 of PCT/IB2019/058219, filed Sep. 27, 2019, which claims the benefit of Italian Patent Application No. 102018000009028, filed Sep. 28, 2018.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of extensible flexible hoses, especially but not exclusively intended for use for irrigation, and more specifically relates to a new configuration for such a hose, and the relative production process.

BACKGROUND OF THE INVENTION

Flexible hoses are known for the passage of a fluid under pressure, mainly a liquid such as irrigation water, the configuration of which is such as to ensure a significant (and automatic) elongation of the hose itself when subjected to the pressure of the liquid inside it, then retreating to the original or rest size when this pressure ceases, i.e. when the tube is emptied. In this way, the handling of the hose when not in use is much simpler and more convenient, due to the reduced overall dimensions.

Among the known hoses that can achieve such a performance such, one can find different technical solutions that are conceptually different from one another, the main ones being the following:the solutions that provide hoses with a corrugated structure, thus extensible in a bellows-like fashion;spiral hoses, in which a wire, generally made of a plastic material, runs in a spiral pattern along the body of the hose (in a polymeric elastic material), and becomes extended in response to the fluid pressure, causing the elongation of the hose, while getting back to the shortened condition when the pressure ceases;hoses in which a layer of textile material is sandwiched between two layers of polymeric elastic material so as to form a unitary structure, the textile material being elastically extensible so as to exert a control of the hose extension similar to that of the above mentioned the spiral wire. This kind of hose structure is disclosed in document EP3323468, in which the above-mentioned textile layer, basically obtained by knitting, weaving or knotting, is co-extruded and welded in a sandwich between two polymeric layers.composite hoses in which an inner tube made of polymeric elastic material is simply inserted, in a loose fashion, inside a tubular textile layer, remarkably longer than the inner tube and therefore wrinkled in the rest condition; however, in response to a radial expansion of the inner tube (subject to the fluid pressure) becomes stretched until it forms a rigid barrier preventing a further radial expansion, thereby forcing the inner tube to extend in elongation.

Focusing on this latter type of solution, which is very interesting especially because a remarkable elongation capability is obtained with reduced production costs, some significant advantages can nevertheless be pointed out.

In the first place, the extension mechanism is such as to determine an abrasive action between the inner tube and the outer layer, in the phases in which the first expands and goes to find the stop action from the outer layer. As these abrasions repeat, with the continuous use of the hose, a rapid deterioration of the hose ensues, and the same hose coms to an early breakage. Even more significant is the weakness at the connections positioned at the ends, and indispensable for use. As mentioned, the inner tube increases its diameter when the liquid under pressure passes, and, encountering the containment barrier from the textile layer, it cannot continue to expand, so that a thrust is generated in the longitudinal direction which allows it to be lengthened. However, in the first phase of the passage of the liquid—and at any subsequent moment of interruption and resumption of the flow of the liquid inside the tube—the tube undergoes an abrupt swelling in all its extension which impacts violently at the end junction point, generating a high risk of damage. At that point, in fact, the material undergoes a particular stress capable of compromising the solidity of the bonds, until they deteriorate and become subject to tearing; this failure risk entails a clear limitation of the possibility of use and of maintaining the desired performance.

Moreover, the wrinkled start state of the outer layer in the hose rest condition causes, in this condition but also during the elongation phase, the possibility that the hose gets caught by protrusions present on its path or in its use environment. The wrinkles also cause the drawback that the hose gets soiled more easily, and is more difficult to clean, a drawback indeed also presented by other types of known extensible hoses with a non-textile exterior, due to the stickiness of the material that forms the exterior wall of the hose.

Furthermore, it must be considered that the above-mentioned extensible hoses are generally structured so that the diameter of the passage duct is, in the working condition, more or less double than that of the rest condition. In composite hoses with an outer tubular layer, due to their extension system, the diameter of the outer layer (as already mentioned, substantially not expandable) clearly corresponds to the working diameter of the inner tube, and is therefore quite big even in the rest condition. Therefore, the hose is rather cumbersome, both in the working condition and even in the rest condition.

It must not be overlooked that, although relatively inexpensive (as it is not very sophisticated from the point of view of production technologies), the assembly process with manual insertion of the inner tube in the tubular outer layer still involves a complication and a lengthening of the production times (and costs).

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome said drawbacks, by providing a flexible extensible hose, in particular but not exclusively for watering fluid, which has a special performance in terms of its extension capability, at the same time ensuring increased durability and reliability with respect to similar known hoses.

A particular object of the present invention is to provide a flexible extensible hose of the above-mentioned type, that takes up minimal space in the rest condition as well as in the working condition.

Another particular object of the present invention is to provide a flexible extensible hose of the above-mentioned type, which has low tendency to get caught on external elements in the environment in which it is used.

A further particular object of the present invention is to provide a flexible extensible hose of the above-mentioned type, which has a reduced tendency to collect and/or adsorb dirt from the environment, and in any case is easily and successfully washable.

An even further object of the present invention is to provide a flexible extensible hose of the above-mentioned type, which can be manufactured with a single-stage productive process and thus with reduced production times and costs.

According to the invention, these objects are attained by the flexible extensible hose and its manufacturing process according to the invention, the essential features of which are defined by claims1and9here attached.

