Pipe joints or couplings – Molded joint – Weld
Reexamination Certificate
1997-06-13
2001-03-13
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
Molded joint
Weld
C264S068000, C156S073500, C228S112100, C285S021100, C285S319000, C285S331000, C285S055000, C285S222100
Reexamination Certificate
active
06199916
ABSTRACT:
INTRODUCTION
The present invention relates to fluid connectors and, more particularly, to the sealing interconnection of such connectors with tubing end forms and, more particularly still, the use of spin welding to effect such interconnection.
BACKGROUND OF THE INVENTION
Quick connect couplings have been widely used in the U.S. Automobile industry for many years. Although applicable in numerous applications, quick connectors are typically employed in fuel systems and vapor recovery systems. The simplest and most cost effective design is the plastic housing female type quick connector releasably mated to a metal male tube endform. The opposite end of the female housing most typically defines a stem having a number of axially spaced barbs forms on the outer circumferential surface thereof and a nylon or plastic tubing endform pressed thereover. Such an arrangement is described in U.S. Pat. No. 5,542,712, issued Aug. 6, 1996, entitled “Quick Connector Housing With Elongated Barb resign”.
In fluid handling systems, it is imperative that the connectors used have their male and female portions properly coupled together. A faulty connector enables an associated system to leak fluid. This can be particularly disadvantageous when the system is under pressure and the leaking connector expels the pressurized fluid. Furthermore, recent federal legislation has mandated significantly reduced hydrocarbon emissions from automotive fuel and vapor recovery systems. Conventional quick connectors, although effective to mechanically maintain tubing endforms in assembly with their associated connector bodies, have not adequately addressed the federal requirements. Also, the materials employed, typically nylon 12, do not provide sufficient resistance to the permeation of hydrocarbons therethrough.
The permeation problem has been addressed in part through the development of co-extruded multi-layer plastic tube containing two or more discreet layers of different types or formulations of plastic, one of which is specifically designed to provide an effective permeation layer, blocking the escape of hydrocarbons from the system. In general the most successful multi-layer tubing employs a relatively thick outer layer composed of a material resistant to the exterior environment. The innermost layer is thinner and is composed of a material which is chosen for its ability to block defusion of materials, such as hydrocarbons, alchohols and other materials present in fuel blends, to the outer layer and may have a degree of electrical conductivity sufficient to dissipate static charges generated by the flow of fluid therein. To date, it has been extremely difficult to obtain satisfactory lamination characteristics between dissimilar polymer layers. Thus, the use of one or more intermediate layers for bonding the inner aid outer layers has been proposed.
The use of multi-layer tubing in fuel related applications has been problematic inasmuch as the tubing endform necessarily exposes the lamina ends of the inner and outer layers as well as any intermediate layers to either the system fuels and vapors or the equally harsh exterior environment. Such exposure tends to degrade the bonding between the various layers, causing delamination or separation of the layers, resulting in loss of system integrity, fuel contamination and even blockage of fluid flow.
A related problem stems from dual aspects of commercially available quick connect devices, to wit: high volume and low sale price frequently necessitating the use of inexpensive, somewhat pliable materials, and complex contours of extremely small inter-fitting components. These aspects collectively increase the likelihood of misassembly. High volume production techniques, including automated assembly tends to aggravate the problem wherein misassembly or impermissible dimensional variations of the components is difficult to detect. Excessive dimensional tolerance stack-up can result in low pull-apart characteristics between the barbed stem and the plastic tube and produce leakage. Misassembly, such as failure to include a O-ring can also result in leakage. In the case of multi-layer tube, dimensional and/or adhesive problems can result in mechanical delamination upon insertion of the tube over the barbed, stem. Finally, mono-wall plastic tube or multi-layer structures with low hoop strength can relax over time or at elevated temperatures, resulting in leaking or weeping of fluid.
BRIEF DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a simple and inexpensive yet mechanically and environmentally robust connection between a tube endform and a connector body as well as an assembly that overcomes the shortcomings of the prior art described hereinabove.
The fluid connector is designed for spin welding connection with a tube. The connector includes a body which defines a through passage which interconnects a first opening which is adapted for receiving a mating conduit and a second opening which is adapted for receiving the tube. The second opening defines surfaces which sealingly engage both the outer and inner peripheral surfaces of the tube. This arrangement has the advantage of reliably sealing the tube endform with the connector body, preventing both fluid leakage and the incursion of environmental contaminants.
In the preferred embodiment of the invention, the fluid connector body defines opposed surfaces for simultaneously sealingly engaging outer and inner peripheral surfaces of the tube. This arrangement has the advantage of ensuring that the outer surface of the tube is sealingly engaged with the connector body and, separately, the inner surface of the tube is sealingly engaged with the connector body, thereby providing a redundant seal.
In the preferred embodiment of the invention, the fluid connector is used in combination with multi-layer tubing having the outer peripheral surface of the outer layer spin weldingly connected to the connector body and the inner peripheral surface of the inner layer separately spin weldingly connected to the connector body. This arrangement provides the advantage of ensuring a hermetic seal at the interface of the inner add outer layers and any intermediate layers of the multi-layered tube from both system fluids and environmental contaminants, thus preventing capillary adsorption into the interface and/or delamination.
According to another aspect of the invention, the connector body includes inner and outer flanges which extend from the body which are concentrically disposed about the second opening, the inner flange defining an outwardly facing welding surface and the outer flange defining an inwardly facing welding surface. The welding surfaces are convergingly tapered to self-center the connector body and tubing during the assembly process and to minimize flow passage restriction of the finalized assembly.
According to still another feature of the invention, the inner and outer flanges are beveled proximate the free ends thereof to, in combination with the tubing, form inner and outer flash traps to house flash generated during the spin welding process. This arrangement has the advantage of providing an aesthetically pleasing external appearance at the point of interface of the tube endform and the connector body and preventing flash from extending radially inwardly into the fluid stream to restrict its flow.
These and other features and advantages of this invention will become apparent upon reading the following specification which, along with the drawings, describe; and discloses preferred and alternative embodiments of the invention in detail.
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patent: 5090745 (1992-02-01),
Klinger Gary O.
Stieler David C.
Zelinski Gary S.
ITT Manufacturing Enterprises Inc.
Nicholson Eric K.
VanWinkle Peter H.
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