FR2572784A1 - Pipe equipped with a double flared end - Google Patents

Abstract

Pipe assembly comprising a metal pipe which is equipped with a double flared end and in which there is tightly fitted a tube formed from a material resistant to corrosion, the double flared end comprising an internal wall part defining a seat for a tubular element to which the pipe assembly is connected, one end of the tube being retained by the inner wall portion. The inner wall portion 5 comprises a conical portion and a cylindrical portion 7 contiguous with the conical portion, the cylindrical portion 7 passing into the tube 2 beyond a collar 6 defining the double flared end 3 and being retained tightly against the internal surface of the tube 2. Application to corrosive fluid pipelines.

Description

 The invention relates to a hose with a double flared end. More particularly, it relates to an improved structure of the flared double end of a metal pipe having a relatively small internal diameter not exceeding approximately 30 mm and a small wall thickness not exceeding approximately 2 mm containing a suitable resin or rubber tube inside tightly, and designed to convey air or corrosive gas or liquid in an automobile or in various apparatus or machines.

 A hose assembly of the type which the invention relates to is described in the application for utility model JP 36485 / 1983. It is represented in FIG. 2. It comprises a metallic hose it containing a resin or rubber tube 12 and provided with a double flared end 13 defined by an elbow directed radially inwards.

This bend defines an interior wall portion 15 having an exterior surface 14 defining a seat for a complementary mount 20. An extremity 2 ′ is retained between the interior wall portion 15 and the exterior wall portion of the double flared end 13. The double flared end 13 is retained against the frame 20 by a nut 19.

 However, as seen in Figure 2, the inner wall portion 15 ends in a radially or conically inclined surface. The inner wall portion 15 tends to resume its original shape elastically before bending and thus does not manage to properly retain the end 12 ′ of the tube 12. When the flared end 13 is bent, the force applied to it by punching tends to move the tube 12 axially and thus create a clearance 16 inside the flared end 13. The flared end 13 therefore does not manage to properly maintain the tube 12. The clearance 16 often allows the fluid reach the inner surface of the pipe Il and corrode it.

 An object of the invention is to provide a hose assembly with a flared double end which is free from the disadvantages of the prior art as indicated above.

 This object is essentially achieved by using a metal pipe provided with an inner wall part defining a flared double end and situated on a conical surface and a cylindrical surface contiguous to it and extending in the axial direction of the pipe.

 Figure 1 is a side elevational view, partially in longitudinal section, of a pipe assembly embodying the invention.

 Figure 2 a view similar to Figure 1, but showing the structure of the prior art as described above.

 As shown in Figure 1, a hose assembly according to the invention comprises a metal hose 1 having a relatively small internal diameter and a small wall thickness and a resin or rubber tube 2 fitted tightly into this hose. the metal pipe 1 and the resin or rubber tube 2 are assembled, for example by joint stretching. The metal pipe 1 has a double flared end 3 directed radially outwards, comprising an inner wall part 5 having an outer surface 4 which defines a seat for a complementary frame 10. The flared end 3 is retained against the frame 10 with a nut 9.

One end of the tube 2 is retained by the double flared end 3.

 According to a notable feature of the invention, the inner wall portion 5 of the flared double end 3 is located not only on a radially inclined or conical surface but also on a cylindrical surface contiguous thereto. In other words, the inner wall part 5 comprises a cylindrical part 7 extending axially into the tube 2 beyond a neck 6 defining the flared end 3. The cylindrical part is defined by a cylindrical proloneeent 8 having a wall thickness reduced and held tightly against the inner surface of the tube 2.

 The improved structure described above prevents any elastic return of the inner wall part 5 and thus allows the end of the tube 2 to be effectively retained by the flared double end 3. When the inner wall part 5 is formed by curvature, the existence of the inner cylindrical extension 7 effectively prevents any axial displacement of the tube 2. There is no play of the kind shown at 16 in Figure 2. Therefore, the fluid is not likely to reach the inner surface of the pipe metallic 1 and corrode it.

Claims (4)

 1) A hose assembly comprising a metal hose which has a double flared end and in which a tube formed of a corrosion-resistant material is closely fitted, the double flared end comprising an inner wall portion defining a seat for a tubular element to which the pipe assembly is connected, one end of the tube being retained by the inner wall part, characterized in that the inner wall part (5) comprises a conical part and a cylindrical part (7) contiguous to the conical part, the cylindrical part (7) penetrating the tube (2) beyond a neck (6) defining the double flared end (3) and being held tightly against the inner surface of the tube (2).  2) An assembly according to claim 1, characterized in that the metal pipe (1) has a relatively small internal diameter and a small wall thickness.  3) An assembly according to claim 1 or 2, characterized in that the corrosion-resistant material is a synthetic resin or a rubber.  4) An assembly according to claim s characterized in that the cylindrical part (7) has a decreasing wall thickness which is less than the wall thickness of the rest of the interior wall part (5).