CONNECTOR FOR HIGH-PRESSURE RUBBER HOSES HAVING IMPROVED TIGHTNESS CHARACTERISTICS

Abstract: A connector for high-pressure rubber hoses, comprising an insert (1) whereon a high-pressure rubber hose is meant to be inserted and a locking ring (2) to lock the rubber hose around the insert, whose particularity is that the insert has, on its outer surface, in a substantially central region, at least one groove (3) which is inclined toward the outlet portion of the insert, in order to guide the distribution of localized tensions and avoid tearing of the rubber of the hose.

Description: CONNECTOR FOR HIGH-PRESSURE RUBBER HOSES HAVING IMPROVED TIGHTNESS CHARACTERISTICS Technical field The present invention relates to a connector for high- pressure rubber hoses having improved tightness characteristics. More particularly, the invention relates to a connector for hoses with helical and braided reinforcing webs. Background Art Conventionally the field of high-pressure hoses generally employs hoses formed with a rubber substrate whereon a reinforcement lining, made of steel or textile yarns, is applied, an additional rubber sheath being arranged over the lining. The high-pressure hoses are connected to each other or to devices by using connectors constituted by an insert, at the ends of which the hoses to be connected are inserted, and by a locking ring which can be fitted over an end of the insert like a sleeve, to anchor the hose to the connector. The high-pressure hose connector, in which for example a fluid such as oil flows, must accordingly ensure both anchoring to the hose and tightness. In practice, it must be able to withstand the stresses induced by the stream of high-pressure fluid that flows inside the hoses, preventing its infiltration between the substrate and the insert, with consequent external leakage of oil. Moreover, since the pressure inside the hose would tend to make the insert exit from the end of the hose where it is inserted, a ring is provided which internally has a toothed profile in order to provide anchoring by making contact with the metallic or textile reinforcement by circumferential clamping. The teeth of the ring can perforate the outer rubber sheath of the high-pressure hose or the sheath can even be removed so that the teeth of the ring rest directly against the reinforcement made of metal or textile material. This type of connector entails a first drawback due to the fact that the pressurized fluid flowing inside the hoses can overcome the contact force of the ring, thus triggering a leak of fluid which passes between the rubber and the insert. A conventional insert generally has quadrangular grooves arranged on its outer surface in order to allow the rubber substrate of the high-pressure hose to enter the cavities formed by the quadrangular grooves and behave like an 0-ring. The drawbacks arise at the outer edges, i. e . , on the blending portions of the grooves , where breakage can be triggered with an unstoppable tendency to propagate . The pressure of the ring on the outer sheath of the rubber hose , during tightening , produces a translatory motion of the underlying hose and causes it to protrude partially because the rubber is incompressible , thus generating a traction stress in the substrate which accordingly can be affected by circumferential tearing. The grooves of the outer surface of the insert are di scontinuit ie s whe re stres ses and de f ormations concentrate , with the consequence that the propagation of tears during use can accelerate . Moreover, under pressure the hose deforms and changes from moving in the region directly ahead of the insert to becoming jammed under the insert. This produces additional cyclic stresses on the edges of the grooves of the insert, adding a dynamic component to the already present static one. To summarize, two contrasting requirements arise: on the one hand it is necessary to provide deep grooves in the insert in order to ensure optimum tightness, but on the other hand it would be desirable to have a substantially smooth profile for the insert in order to avoid the accumulation of stresses at the edges of the grooves, particularly at the edge that is upstream of the end portion of the insert. Disclosure of the Invention The aim of the present invention is to provide a connector for high-pressure rubber hoses in which the tightness and reliability characteristics are improved with respect to a conventional connector. Within the scope of this aim, an object of the present invention is to provide a connector for high-pressure rubber hoses in which the axial sliding of the rubber of the hose is facilitated during ring compression, avoiding immobility, jamming and tearing of the material. Another object of the present invention is to provide a connector for high-pressure rubber hoses in which one of the two discontinuities of adjacent grooves can be eliminated in order to reduce the concentration of stresses. Another object of the present invention is to provide a connector for high-pressure rubber hoses in which the insert can be adapted to a plurality of different rings, hoses and tightening systems, since it closely resembles the ideal configuration of a smooth insert. Another object of the present invention is to provide a connector for high-pressure rubber hoses in which ring tightening allows better stress distribution. Another object of the present invention is to provide a connector for high-pressure rubber hoses which is highly reliable, relatively easy to manufacture and at competitive costs. This aim, these objects and others which will become apparent hereinafter are achieved by a connector for high- pressure rubber hoses, comprising an insert whereon a high- pressure rubber hose is meant to be inserted and a locking ring to lock the rubber hose around the insert, characterized in that said insert has, on its outer surface, in a substantially median region, at least one asymmetric groove which is inclined toward the outlet portion of the insert, in order to guide the distribution of localized tensions and avoid the risk of tearing in the elastomeric substrate of the hose. Brief Description of the Drawings Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment of the connector according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a side view of an insert which is part of the connector according to the present invention; Figure 2 is a side view of a ring which is part of the connector according to the present invention; and Figure 3 is an enlarged view of a detail of the profile of one of the grooves formed on the outer surface of the insert in the connector according to the present invention. Ways of carrying out the Invention With reference to the above figures, the connector according to the invention comprises an insert 1, shown in Figure 1, and a ring 2, shown in Figure 2. The insert 1 is constituted by a substantially cylindrical body which has, on its outer surface, at least one groove 3 inclined toward the end for the insertion of the insert 1 in a rubber hose (not shown). Advantageously, it has been observed that it is ideal to provide a number of grooves 3 which can vary between one and six according to the size of the insert, but it is possible to provide a different number of grooves as deemed convenient. The grooves 3 have a profile as shown in detail in Figure 3. Each groove 3 therefore has, from the upstream region toward the downstream region of the insert, a first straight portion 4, parallel to the axis of the insert 1, and a first inclined portion 5, which is blended along a curved profile with the first straight portion 4 and, also with a curved profile, with a second inclined portion 6, which in turn is blended with a second straight portion 7 which is also parallel to the axis of the insert 1. The deepest point of the groove 3 is arranged asymmetrically with respect to the centerline of the groove. The inclination α of the second inclined portion 6 with respect to the second straight portion 7 can be variable, for example between 1 and 30 degrees. The grooves 3 are arranged in a central region of the portion of the insert 1 that is meant to be inserted in the rubber hose and are preceded, in an upstream region, by a plurality of microgrooves 12, which have a quadrangular profile and are of the conventional type, and in a downstream region by a conical-cylindrical portion 8 which allows the mobility of the rubber hose to be damped gradually. The conical-cylindrical portion thus allows the cyclic contractions of the rubber hose to be damped gradually. The microgrooves 12 having a more conventional profile have the purpose of providing an additional seal of the labyrinth type, which becomes effective mainly in advanced aging conditions. The ring 2 is instead shaped so as to have a profile with annular portions whose outside diameter increases from the region 9 meant to be arranged at the last groove 3 to the region 10 meant to abut against a flange 11 of the insert 1. The inclined portion 6 of each one of the grooves 3 also increases tightness against infiltrations of fluid, since the radial compression applied by the ring 2 to the high-pressure hose fitted over the insert 1, by acting on an inclined plane, generates an axial component which would tend to make the insert 1 exit from the rubber hose; this is prevented by the continuity constraint, so that the resultant at right angles to the inclined plane is greater than the radial component, thus increasing the sealing effect of the rubber of the hose on the profile of the insert 1. In practice it has been observed that the connector according to the invention fully achieves the intended aim, since it allows to increase the tightness of the rubber hose around the insert by means of the clamping action applied by the outer ring. The grooves, having a negative profile and inclined toward the outlet region of the insert, allow to reduce the stresses applied to the rubber of the hose when a high- pressure fluid flows inside it, producing mobility of the rubber hose on the insert and therefore producing damaging jamming of the rubber on the edges of the grooves required to ensure tightness. In this manner, the grooves formed on the insert according to the invention act as stress reduction elements. This is also allowed by the coupling with the locking ring, since the compression force applied by the ring acts on the rubber of the hose which, being incompressible, is elongated toward the outlet region of the insert and thus redistributes along the insert, being assisted in this by the circular cross-section of the ring, which decreases in diameter toward the outlet portion of the insert, and by the cylindrical-conical configuration of the outlet portion of the insert. Another advantage of the connector according to the present invention is provided by the fact that the greater uniformity of the stresses transmitted from the insert to the rubber hose as a consequence of the movements of said hose with respect to conventional insert types makes it less difficult to match the profile of the insert with the profile of the ring and thus considerably increases the possibility to standardize the insert, using it accordingly on a large number of hoses with different types of ring and tightening system. This entails a saving in production costs and a reduction of inventory. The connector thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept. Thus, for example, it is possible to provide, instead of the conventional grooves having a quadrangular profile 12, a plurality of microgrooves which allow to increase tightness. Finally, all the details may be replaced with other technically equivalent elements. In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art.

Claims: CLAIMS 1. A connector for high-pressure rubber hoses, comprising an insert whereon a high-pressure rubber hose is meant to be inserted and a locking ring to lock the rubber hose around the insert, characterized in that said insert has, on its outer surface, in a substantially median region, at least one asymmetric groove which is inclined toward the outlet portion of the insert, in order to guide the distribution of localized tensions and avoid the risk of tearing in the elastomeric substrate of the hose. 2. A connector for high-pressure rubber hoses according to claim 1, characterized in that said at least one groove has a profile defining a cavity which has a rounded bottom, the deepest point wherof is axially offset with respect to the centerline of said groove. 3. A connector for high-pressure rubber hoses according to claim 2, characterized in that said at least one groove has a profile comprising a first straight portion which blends, along a curved portion, with a first inclined portion which blends with a second inclined portion which is asymmetric with respect to the first portion and in turn blends with a second straight portion, said first and second straight portions being parallel to the longitudinal axis of said insert. 4. A connector for high-pressure rubber hoses according to claim 1, characterized in that said insert has, in a region upstream of said at least one groove, a plurality of grooves having a quadrangular profile. 5. A connector for high-pressure rubber hoses according to claim 1, characterized in that said insert has, in a region upstream of said at least one groove, a plurality of microgrooves. 6. A connector for high-pressure rubber hoses according to claim 1, characterized in that said insert has, downstream of said at least one groove, a cylindrical- conical portion. 7. A connector for high-pressure rubber hoses according to claim 1, characterized in that said ring is constituted by a substantially cylindrical body which is formed by rings whose diameter increases from the portion that is meant to be directed toward the outlet of said insert to the portion that is meant to abut against a shoulder of said insert. 8. An insert for connectors for high-pressure rubber hoses, comprising a substantially cylindrical body which has a region meant to be inserted in a rubber hose, characterized in that it comprises, on its outer surface and in a central region, at least one groove which is inclined toward the outlet portion of the insert in order to guide the distribution of localized tensions and avoid tears in the elastomeric substrate. 9. An insert for connectors for high-pressure rubber hoses according to claim 8, characterized in that said at least one groove has a profile which forms a cavity having a rounded bottom, the deepest point whereof is axially offset with respect to the centerline of said groove. 10. An insert for connectors for high-pressure rubber hoses according to claim 9, characterized in that said at least one groove has a profile comprising a first straight portion; said straight portion blends along a curved portion with a first inclined plane which blends with a second inclined portion, which is in turn blended with a second straight portion , said f irst and second straight portions being parallel to the longitudinal axis of said insert . 11. An insert for connectors for high-pressure rubber hoses according to claim 8 , characterized in that said insert has , in a region upstream o f said at least one groove , a plurality of grooves having a quadrangular profile . 12. An insert for connectors for high-pressure rubber hoses according to claim 8, characterized in that said insert has, in a region upstream of said at least one groove, a plurality of microgrooves. 13. An insert for connectors for high-pressure rubber hoses according to claim 8, characterized in that said insert has, downstream of said at least one groove, a conical-cylindrical portion. 14. A ring for connectors for high-pressure hoses, comprising a substantially cylindrical body, characterized in that said ring is formed by annular portions whose diameter increases from a region that is meant to be directed toward the outlet of an insert whereon said ring is positioned to a region that is meant to abut against a flange of said insert.

Inventors: AMADEI VITTORIO, SEGHI PAOLO, AMADEI, VITTORIO, SEGHI, PAOLO
Applicants: AMADEI VITTORIO, MANULI RUBBER IND S P A, SEGHI PAOLO, AMADEI, VITTORIO, MANULI RUBBER INDUSTRIES S.P.A., SEGHI, PAOLO
Application year: 1998
Main classification: F16L33
IPC codes: F16L33