A connection and/or T-joint for flexible tubes

Abstract: The connection and/or T-joint includes a rigid tubular insert (2) with at least two ends (2a, 2b, 2c) onto which the ends of flexible tubes (A, B, C) are force-fitted. A cover (6) of plastics material is moulded over the tubular insert (2) and over the ends of the tubes (A, B, C). At least one respective integral, circular sealing lip (5) projects from the internal surface of the end of each tube (A, B, C) and engages the external surface of the corresponding end (2a, 2b, 2c) of the insert (2).

Description: The present invention relates to a connection and/or T-joint for flexible tubes, particularly for fluid circuits such as cooling systems for motor vehicles, of the kind defined in the introduction of Claim 1. EP-A-286 973 discloses a connection of this kind in which each end of the insert is provided with a single external projection having a saw-tooth profile and with a further projection serving as an abutment for the tube fitted thereon. The tubes have respective end portions which are pre-shaped so that their internal profile corresponds to external profile of the associated end portion of the insert. EP-A-0 080 110 discloses a tube having one end provided with an internal annular sealing element which forms a number of internal circular lips or ribs which, when the tube end is fitted onto an insert, act as shut-off valves improving the tightness of the connection. GB-A-633 351 discloses a hose-end fitting in which the hose is disposed around an insert provided with a plurality of external saw-tooth projections, The hose is provided with a plurality of external grooves for keying a cap to the hose. A plastics material is overmoulded on the hose-insert junction and also fills the said grooves. The object of the present invention is to provide an improved connection and/or T-joint of the aforesaid type which can remain functional even when the fluid circulating in the tubes reaches quite high pressures, for example, of the order of tens of bars. This object is achieved, according to the invention, by means of a connection and/or T-joint having the features defined in Claim 1. Further characteristics and advantages of the invention will become clear from the detailed description which follows with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is a sectional view of a connection according to the invention forming a T-joint between three flexible tubes, Figure 2 shows the detail indicated II in Figure 1, on an enlarged scale, Figure 3 is a sectional view of the end of a flexible tube shown before it is fitted onto the tubular insert of the connection according to the invention, and Figure 4 shows the detail indicated IV in Figure 3, on an enlarged scale. In Figure 1, three flexible tubes, indicated A, B and C are joined together in a T-joint according to the invention, generally indicated 1. The tubes are made, for example, of an elastomeric material, possibly reinforced with internal or external fabric reinforcement. A rigid T-shaped tubular insert, for example, of plastics material is indicated 2. The insert 2 has three end portions 2a, 2b and 2c with respective pluralities of external axially-spaced perimetral projections 3 which, in the embodiment shown by way of example, have sawtooth-shaped cross-sections. The ends of the flexible tubes A, B and C are force-fitted onto the ends of the tubular insert 2. As can best be seen in Figures 2 to 4, the end of each tube has an external perimetral groove 4. Moreover, an integral, flexible, circular sealing lip, indicated 5, projects radially inwardly from the internal surface of the end of each tube. The lip is formed substantially in the same cross-section of the tube as the groove 4 (see Figures 3 and 4 in particular). When the ends of the tubes A, B and C are force-fitted onto the ends 2a, 2b and 2c of the tubular insert 2, the internal sealing lips 5 of each end are disposed between two adjacent perimetral projections 3 of the corresponding end of the tubular insert. The lips are squashed against the outer surface of the end of the tubular insert, as can be seen in Figures 1 and 2. After the tubes A, B and C have been fitted onto the ends of the tubular insert 2, a cover of plastics material, indicated 6 in Figures 1 and 2, is moulded over the insert and over the ends. The cover may be made of a polyamide or of glass-filled polypropylene with a low coefficient of contraction. At the moulding stage, the material which forms the cover 6 penetrates and thoroughly fills even the grooves 4 in the ends of the tubes. The moulded cover 6 ensures that the joint between the tubes is fluid-tight. If the pressure of the fluid circulating through the joint becomes excessive, the tubes A, B and C may expand. The fluid circulating through the joint can then penetrate between the outer surface of the end of the tubular insert and the internal surfaces of the ends of the tubes. The penetration of the fluid under pressure is then effectively blocked by the lips 5 of the ends of the tubes which, since they are bent and are urged against the outer surfaces of the ends of the tubular insert, act like shut-off valve elements. Further penetration of the pressurised fluid into the region in which the material of the cover 6 adheres to the outer surfaces of the ends of the tubes is thus prevented or at least greatly obstructed. Tests carried out by the Applicant have shown that joints formed according to the invention can withstand extremely high excess pressures, particularly pressures of the order of tens of bars. In embodiments of the invention which are not shown, the T-joint can house drain valves and/or plugs of plastics material or of metal, fitted in the rigid insert 2 or in the cover 6. Moreover, the joint may be formed as a double T or with a curved main body from which one or more branches extend, or in other shapes usually used for conventional joints or, more simply, may be formed so as to join only two tubes. Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the present invention as defined in the appended Claim.

Claims: A connection and/or T-joint for flexible tubes (A, B, C), particularly for fluid circuits, including: a rigid tubular insert (2) with at least two ends (2a, 2b, 2c), at least two flexible tubes (A, B, C) the ends of which are force-fitted onto the ends (2a, 2b, 2c) of the tubular insert (2), and a cover of plastics material (6) moulded over the tubular insert (2) and over the ends of the tubes (A, B, C) which are fitted onto the insert (2), the ends (2a, 2b, 2c) of the insert (2) having respective external perimetral projections (3) with a saw-tooth profile, the end of each tube (A, B, C) having an external perimetral recess (4) into which the moulded cover (6) extends; characterised in that each end (2a, 2b, 2c) of the insert (2) has at least two axially-spaced external projections (3) with a saw-tooth profile, the tubes (A, B, C) have each a respective end portion which extends beyond all of the said at least two external saw-tooth projections (3) of the insert (2), said external recess of each tube (A, B, C) is a groove (4) which is formed in a position such that it extends axially between two adjacent saw-tooth projections (3) of the insert (2); the groove (4) having an axial extension which is less than the distance between said adjacent saw-tooth projections (3) of the insert (2), from the internal surface of the end of each tube (A, B, C) extending at least one integral, axially flexible circular sealing lip (5) which, before the force-fitting of the tube (A, B, C) onto the insert (2), has an internal diameter which is less than the external diameter of the portion of the insert (2) comprised between said two adjacent saw-tooth projections (3); said sealing lip (5) extending in an axial position substantially corresponding to that of said groove (4), whereby in the mounted condition of the tube (A, B, C) on the insert said sealing lip (5) is bent and urged against the outer surface of the insert (2) between said two adjacent saw-tooth projections (3).

Inventors: MOGAVERO CESARE, MOGAVERO, CESARE
Applicants: SAIAG IND SPA, SAIAG INDUSTRIA S.P.A.
Application year: 1993
Main classification: F16L33
IPC codes: F16L47, F16L33, F16B7