HIGH TEMPERATURE RESISTANT MULTILAYER TUBING

Abstract

A multilayer plastic tubing for motor vehicles includes a first layer of tubing and a second layer of tubing positioned about the first layer of tubing. The first layer is stiffer and thinner than the second layer.

Claims

1. A multilayer plastic tubing for motor vehicles comprising: a first layer of tubing; and a second layer of tubing positioned about the first layer of tubing, wherein the first layer of tubing is stiffer than the second layer of tubing and is thinner than, thicker than or has the same thickness as the second layer of tubing.

2. The multilayer plastic tubing of claim 1 further comprising a layer of adhesive positioned between the first layer of tubing and the second layer of tubing to adhere the first layer of tubing and the second layer of tubing together.

3. The multilayer plastic tubing of claim 2 wherein the adhesive is made of a modified polyolefin with functional groups.

4. The multilayer plastic tubing of claim 1 wherein the first layer of tubing is made of a polyphenylene sulfide (PPS).

5. The multilayer plastic tubing of claim 4 wherein the second layer of tubing is made of polyphthalamide (PPA).

6. The multilayer plastic tubing of claim 5 wherein the multilayer plastic tubing is capable of operating at a maximum continuous temperature of about 180 C.

7. The multilayer plastic tubing of claim 5 wherein the multilayer plastic tubing is capable of operating at a maximum continuous pressure of about 550 kPa.

8. The multilayer plastic tubing of claim 4 wherein the second layer of tubing is made of a polyamide 612 (PA612).

9. The multilayer plastic tubing of claim 8 wherein the multilayer plastic tubing is capable of operating at a maximum continuous pressure of about 275 kPa.

10. The multilayer plastic tubing of claim 1 further comprising a layer of conductive material positioned on the interior of the first layer of tubing.

11. The multilayer plastic tubing of claim 10 wherein the layer of conductive material is made of polytetrafluoroethylene.

12. A multilayer plastic tubing for motor vehicles comprising: a first layer of tubing made of PPS; a second layer of tubing positioned about the first layer of tubing; and a layer of adhesive positioned between the first layer of tubing and the second layer of tubing to adhere the first layer of tubing and the second layer of tubing together, wherein the first layer of tubing is stiffer than the second layer of tubing and is thinner than the second layer of tubing.

13. The multilayer plastic tubing of claim 12 wherein the adhesive is made of a modified polyolefin with functional groups.

14. The multilayer plastic tubing of claim 12 wherein the second layer of tubing is made of polyphthalamide (PPA).

15. The multilayer plastic tubing of claim 12 wherein the second layer of tubing is made of a polyamide 612 (PA612).

16. The multilayer plastic tubing of claim 12 further comprising a layer of conductive material positioned on the interior of the first layer of tubing.

17. The multilayer plastic tubing of claim 16 wherein the layer of conductive material is made of polytetrafluoroethylene.

18. A multilayer plastic tubing for motor vehicles comprising: a first layer of tubing made of PPS; a second layer of tubing positioned about the first layer of tubing, the second layer of tubing being made of PPA; and a layer of adhesive positioned between the first layer of tubing and the second layer of tubing to adhere the first layer of tubing and the second layer of tubing together, wherein the first layer of tubing is stiffer than the second layer of tubing and is thinner than the second layer of tubing.

19. The multilayer plastic tubing of claim 18 further comprising a layer of conductive material positioned on the interior of the first layer of tubing, the layer of conductive material being made of polytetrafluoroethylene.

20. The multilayer plastic tubing of claim 19 further comprising a layer of adhesive to bond the layer of conductive material to the first layer of tubing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0026] FIG. 1 is a cross-sectional view of a multilayer tubing in accordance with the principles of the present disclosure; and

[0027] FIG. 2 is a cross-sectional view of the multilayer tubing shown in FIG. 1 with an additional layer of a conductive material.

DETAILED DESCRIPTION

[0028] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0029] Referring to FIG. 1, there is shown a multilayer plastic tubing 10 for motor vehicle applications. The multilayer plastic tubing 10 includes a first layer of tubing 14 with a thickness t.sub.2 positioned within a second layer of tubing 12 having a thickness t.sub.1. Optionally a layer of adhesive 16 with a thickness t.sub.3 may be utilized to adhere the first layer of tubing 14 and the second layer of tubing 12 together. The first layer of tubing 14 is stiffer than the second layer of tubing 12.

[0030] In a particular application, the first layer of tubing 14 and the second layer of tubing 12 have thicknesses between about 0.25 mm and 5 mm with the thickness t.sub.2 of first layer of tubing 14 being less than the thickness t.sub.1 of the second layer of tubing 12. The first layer of tubing 14 can be made from polyphyenylene sulfide (PPS) and the second layer of tubing 12 can be made from polyphthalamide (PPA). The thinness of the first layer of tubing 14 assures the flexibility of the multilayer plastic tubing 10 while the stiffness of the first layer of tubing maintains support for the multilayer plastic tubing 10 under conditions of pressurization or a vacuum at high temperatures. The multilayer plastic tubing 10 is configured for maximum continuous operating temperatures of about 180 C.

[0031] In general, the thickness t.sub.3 of the adhesive layer 16 is thinner than both the thicknesses t.sub.1 and t.sub.2 of the first layer of tubing 14 and the second layer of tubing 12, respectively. In some applications the layer of adhesive 16 is made from, for example, a modified polyolefin with functional groups, or can be made from any other suitable material. The multilayer plastic tubing 10 is suitable for use in motor vehicle applications that experience high pressures of about, for example, 550 kPa and high temperatures of about, for example, 180 C., such as, for example, transmission oil cooler (TOC) application or engine oil cooler applications (EOC). In other applications, such as for example to transmit vapor gases which may experience pressures of about 200 kPa, the thicknesses of the first layer of tubing 14 and the second layer of tubing 12 are thinner than for TOC or EOC applications.

[0032] In other low pressure applications that are less demanding than TOC or EOC applications that experience pressures of, for example, 100 kPa to 275 kPa, the second layer of tubing 12 can be made from a polyamide 612 (PA612) rather than from PPA. The PA612 is also less robust at high temperatures than PPA. PA612, however, is cheaper than PPA. The PA612 can have a thickness between about 0.25 mm and 5 mm. The PA612 layer 12 is generally thicker than the PPS layer 14. Again, an optional layer of adhesive 16 may be employed to adhere the PA612 layer 12 and the PPS layer 14 together.

[0033] In certain applications of the multilayer plastic tubing 10, a layer of conductive material 18 (FIG. 2) can be positioned on the interior of the first layer of tubing 14, for example, when the tubing 10 is utilized for the transmission of liquid fuel. An optional layer of adhesive may be utilized to adhere layer of conductive material 18 to the first layer of tubing 14. The layer of conductive material 18 can be made from polytetrafluoroethylene (PTFE) and can have a thickness of about 0.1 mm. Note that such a conductive layer is not necessary for the transmission of fuel vapors.

[0034] In any of the above applications, the first layer of tubing 14 and the second layer of tubing 12 can be cut to length and then reheated in a forming fixture such that the multilayer plastic tubing 10 takes a specific configuration. To connect the multilayer plastic tubing 10 to the desired system, the ID of the multilayer plastic tubing 10 can be forced over barbs molded in the OD of a plastic fitting connected to the system. Alternatively, the multilayer plastic tubing 10 can be spin-welded onto the plastic fitting. More specifically, the ID of the multilayer plastic tubing 10 is placed over the OD of the plastic fitting forced over the plastic fitting until the end of the multilayer plastic tubing 10 abuts the connector body. The connector is then rotated rapidly until frictional forces melts the plastic surfaces. The cooling of the plastic creates a bond between the connector and the end of the multilayer plastic tubing 10. If the connector is made of metal, the tubing 10 is usually forced over an upset on the metal stem of the connector. If a quick-connector is utilized on the end of the multilayer plastic tubing 10, the port end (that is, the female end) of the connector snaps onto a plastic or metal tube with an end upset designed to lock into the port end.

[0035] The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.