MXPA01005224A - Connecting device for metal conduit - Google Patents

Abstract

The invention concerns a connecting device for a metal conduit (C) comprising a functional section for connecting the conduit to a member and a section (3) for linking the functional to the metal conduit, the connecting device being made of a thermoplastic material, the linking section being tubular and extends beyond the functional section, and said linking section comprising a cylindrical portion (5) of substantially constant thickness (e) and provided externally with a deformable ring-shaped sealing element (8) dividing the cylindrical portion (5) into two parts at least as long as the thickness of the sealing element, and a catching portion (9, 10) extending radially recessed relatively to the cylindrical portion to form a housing for a deformed portion (C1) of the metal conduit.

Description

CONNECTION DEVICE FOR A MET PIPE The present invention relates to a connection device for a metal tube to the member to be joined, which can be used in particular in the fuel circuit of a motor vehicle.

In the case of internal combustion engine vehicles, the fuel is generally transported to the feed bodies by means of tubes made of thermoplastic connected together or by means of connection devices also made with thermoplastic. In general terms, the connection must be watertight and adequate to withstand the tensile forces of the tube according to the longitudinal and transverse directions of the same, the hermeticity should not be modified due to the application of these efforts. Such a connection device of a thermoplastic tube consists of a functional section comprising a functional section designed to relate to a tube or an organ to be joined and a section of connection of the functional section to the thermoplastic tube. The joining section is formed by the male part having reliefs on the outside, for example spruce teeth, and was designed to be press-fitted to one end of the tube. These thermoplastic elements ensure a tight connection, resistant and, at the same time, light and simple to execute.

However, in a certain type of engine such as direct injection engines, the temperature of the transported fuel exceeds 130 ° C in certain areas of the circuit. Consequently, the fuel undergoes a global warming in the circuit at a temperature at which the thermoplastic material of the tubes does not have sufficient stability that allows them to ensure their function. So it is used to metal tubes, for example aluminum. The connection for a metal tube is carried out by crimping the tube on the connecting section of a connecting device. The connection devices used are metal, such as brass or steel, and has a joining section that has external reliefs in order to increase the resistance to tearing of the tube once it is connected. The mechanical strength of a metallic connection device allows them to withstand significant crimping forces which cause a close contact of the inner surface of the contact with the external surface of the connecting section of the connecting device. The tightness of the connection is due to close contact. The connections made in this way have satisfactory characteristics of tightness and resistance to tearing. However, the metal connection elements are heavy and relatively expensive.

So it was thought to use thermoplastic connection devices having a similar shape to those connection devices used previously. However, it was calculated that the mechanical strength of the thermoplastic materials would not be sufficient to prevent the connection device from breaking due to the effect of the crimping stress and it would be necessary to introduce, before making the crimping of the tube, a mandrel in the device of connection in order to sustain it and to increase the transverse efforts, as well as the crimping effort. The above would mean a delicate work, especially for elbowed connection devices in which it is not feasible to introduce a mandrel before crimping. The idea of using thermoplastic connection devices together with the metal tubes had not been investigated.

The invention is the product of an analysis against prejudice and proposes a thermoplastic connection device having a geometry adapted to withstand the entanglement efforts of a metal conduit.

For this, a connection device for a metal tube, comprising a functional section designed to connect the tube, was prepared according to the invention. metal to an organ and a section connecting the functional section to the metal tube, the thermoplastic connecting device, the connecting section is tubular in shape and extends beyond the functional section, the connecting section comprising a cylindrical part of substantially constant thickness and provided on the outside with a deformable annular sealing element which divides the cylindrical part in two parts of at least equal length to the dimension of the sealing element parallel to a longitudinal direction of the cylindrical portion, and a hook part extending radially in relation to the cylindrical part to create a housing for a deformed part of the metal tube.

This geometry allows the joining section to have resistance to the crimping stress of the metal tube as well as providing the connection with a good tightness and a high resistance both to axial tensile stresses and to lateral forces. In addition, the determined minimum length of the two parts of the cylindrical part makes it possible to ensure a sufficient longitudinal reach of the pipe connected in the conduction area, limiting the deformation of the pipe strut to the level of the sealing element.

Fortunately, the lengths of the parts of the cylindrical part are practically the same. The forces applied in the area of conduction, and in particular in the crimping of the tube, are therefore distributed in equal proportion in one part and in the other of the sealing element.

Preferably, the length of the cylindrical area is practically equal to two thirds of the total length of the joining section. The connecting device thus made allows to optimize both the crimping stress resistance and the tear resistance.

According to the particular embodiment, the engagement area extends between the cylindrical area and the functional section.

It is positive that the joining section is a piece of revolution, the engagement area preferably comprising a truncated cone with a small base forming the aforementioned gap. Then, the joint surface allows a relative freedom of rotation of the metal tube in the connection device around the longitudinal axis of the tube. This feature facilitates the subsequent mounting of the tube in the vehicle, which allows orienting it in relation to the organs to be joined. This orientation is carried without altering the tightness assured by the sealing element.

According to a particular feature, the sealing element is an annular gasket placed in the throat which reaches practically half of the cylindrical area to exit the outer surface of the cylindrical area. The connection device is easy to install. Due to the fact that the throat is in the middle, the efforts that apply, after the crimping I of the metal tube, in each part of the cylindrical area extending to one part and to the other of the throat are equitable. In this way the occurrence of shear stress in the throat is prevented.

Other features and advantages of the invention will be apparent upon reading the description thereof, as well as the particular, but not limiting, embodiment method.

Reference will be made to the attached figures, which are described below: - Figure 1 is a scale view of the connection device according to the invention; - Figure 2 is a view similar to Figure 1 of the connection device, a metal tube, in longitudinal section, being connected in the connection section of the connection device.

In relation to the figures, the connection device according to the invention, generally designed in 1, consists of a functional section 2 and a joining section 3 of the functional section to a metal tube C of, for example, aluminum or copper. The connection device can be straight or bent.

The connection device according to the invention is carried out by injection into a mold of thermoplastic material such as polyamide.

The functional section 2 can be a part of the organ to be connected to the metal tube, for example a reservoir, a pump or any other, or to be a part of a ferrule that constitutes the connection device, the functional section that to its it comprises the connecting means with an organ of the aforementioned type or another thermoplastic, metal or elastomer tube.

The connecting section 3 extends perpendicularly and is a flange of a surface 4 of functional section 2 and has a total length L.

The connecting section 3 is a piece of tubular revolution that delimits the internal channel with a pitch diameter that corresponds to the desired output of the fluid in the connection device.

The connecting section 3 comprises, from the side of its free end, a cylindrical area 5 with a length 1_. The length 1_ is almost equal to two thirds of the total length L. The thickness e of the cylindrical area 5 is substantially the same along the length 1_ of the aforementioned cylindrical area 5. The thickness e is determined in relation to the resistance that the cylindrical area 5 must show before the stresses to which the metal tube C in the joining section 3 is subjected due to its use.

The cylindrical area 5 has a chamfer 6 that extends parallel to the free end to facilitate the introduction of the joining section 3 into the tube C.

A throat 7 is practically in the middle of the cylindrical area 5 to accommodate an annular gasket 8 a little outlet, radial, in relation to the cylindrical area 5 to form a compressible tightness element. The groove 7 divides the cylindrical area 5 into two parts of at least the same width as that of the groove 7 corresponding to the thickness of the joint 8. The depth of the groove 7 is calculated to weaken the cylindrical area 5 to a minimum. The sealing element can likewise be carried out in one piece together with the connection device taking the form of a compressible tightness bearing projecting around the cylindrical area 5. The sealing element can have a deformable annular lip protruding around the cylindrical area. The annular lip is for example of polyamide or of any other plastic material. The connection device can be made by injection of two materials, one of polyamide for the body of the device itself and the other based on elastomers for the sealing element. Also, a sequential injection process can be used, the polyamide then being both the body of the device and the sealing element, for example. It is possible that the sealing element lies along the cylindrical area 5.

A truncated cone 9 is located between the surface 4 and the cylindrical area 5 and its small base 10 is connected to the Cylindrical area 5. The small base 10 is radially uneven in relation to the cylindrical area 5 so that a truncated cone 9 forms an area of engagement of the tube. The small base 10 can, if necessary, be joined to the cylindrical area 5 by means of a cylindrical extension.

The large base of the truncated cone 9 is joined to the surface 4 by means of a complementary cylindrical area 11 of external diameter D greater than the external diameter d of the joint 8. The complementary cylindrical area is optional.

The different parts of the connecting section 3 are preferably joined together by means of joints for the purpose of limiting the breaking zones.

For example, the connection device may have the following dimensions: L = 30 mm, 1 = 13 mm, a = 2 mm, Id = 5.5 mm, e = 2 mm, D = 9.3 mm, d = 9 , 2 mm, step diameter = 5 mm.

Referring to Figure 2, before placing the tube C in the connection device, the end of the tube C is flowered so that its internal diameter is a little greater than the diameter D. Then, the connecting section 3 is inserted into the the aforementioned end until it meets the surface 4.

Then, the tube C is supported by the complementary cylindrical area 11, focusing on it and facilitating the subsequent crimping. It will be noted that the flowering of the end of the tube C to a diameter greater than the outer diameter d of the joint 8 makes it possible in particular to prevent the seal 8 from going bad when the connecting section 3 is inserted at the end of the tube C.

Subsequently, the end of the tube C is crimped into the joining section 3 for example by a magnetic crimping process, called magnetostriction, or by a mechanical crimping process. Hence, the cylindrical area 5 supports most of the crimping stress exerted on the connecting section 3 by means of the tube.

After crimping, the end of the tube C takes the form of the joining section 3. A truncated cone 9 consequently constitutes a housing for a deformed part Cl of the tube C. A part C2 of the tube C comes into contact with the cylindrical area 5 and compresses the seal 8 thus ensuring the tightness of the joint.

The invention is not limited to the embodiment described here, but covers any variant that take up again, together with the equivalent means, the essential characteristics mentioned above.

In particular, the joining section 3 can be arranged so that the engagement area encompasses the side of the free end and the cylindrical area is located between the engagement area and the functional section.

Although the connecting section 3 is represented in the form of a piece of revolution, the connecting section 3 can have polygonal parts.

Claims (9)

1. Connection device for a metal tube, comprising a functional section designed for the connection of the tube to an organ and a connection section of the functional section to the metal tube, in which the connecting device is made of thermoplastic, the connecting section it is tubular and extends beyond the functional section, and this junction section comprises a cylindrical area of practically equal thickness and externally provided with a deformable annular sealing element that divides the cylindrical area into two length parts (Id more or less equal to the dimension of the sealing element parallel to a longitudinal direction of the cylindrical area, and an engagement area having a radial unevenness in relation to the cylindrical area with the purpose of constituting a housing for a deformed part (Cl) of the metallic tube.

2. The connecting device according to claim, wherein the lengths (1 ') of the parts of the cylindrical area are substantially equal.

3. The connection device according to claim 1 or claim 2, wherein the area Cylindrical has a length practically equal to two thirds of the length (L) of the joining section.

4. The connection device according to one of claims 1 to 3, wherein the engagement area lies between the cylindrical area and the functional section.

5. The connection device according to claim 4, wherein the joining section is a piece of revolution.

6. The connection device according to claim 5, wherein the engagement area comprises a truncated cone with a small base forming said unevenness.

7. The connection device according to claim 6, wherein the joining section comprises an additional cylindrical area lying between a truncated cone and the surface of the functional section and with a larger diameter than the external diameter of the sealing element (8) and corresponding to an inner diameter of the tube before crimping.

8. The connection device according to any of the preceding claims, wherein the element of Airtightness is an annular gasket placed in a throat that is substantially in the middle of the cylindrical area so that it protrudes from the outer surface of the cylindrical area.

9. The connection device according to any of the preceding claims, wherein the cylindrical area is a chamfer on the side opposite the engagement area.