Patent Publication Number: US-7581761-B2

Title: Asymmetric hose coupling endform for fluid transfer assemblies

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a coupler device for hose connections and to a method for connecting such endform to a hose. More particularly, the present invention relates to a coupling endform device including a barb having an asymmetric barb profile which provides improved coupling retention and sealing properties while requiring no additional coupling effort during assembly of the coupling device to a hose, compared to a conventional coupling device having a symmetrical circular barb profile. 
     Hose coupling endform devices are known. For example, commonly assigned U.S. Pat. No. 6,880,862 to Mobley teaches a coupling device for connecting a polymeric tubing having a first conductive inner surface to the open end of a hose having a second conductive surface such that conductive continuity is maintained between the polymeric tube and the hose. U.S. Pat. No. 3,653,692 to Henson describes an elastomeric hose connected to a nipple having a circumferential barb. The hose is stretched allowing a ring member to slide down the hose and over the barbed nipple where it creates a compression on the hose when the hose is no longer stretched. U.S. Pat. Nos. 6,733,047 to Stieler; 6,637,779 to Andre; 6,634,679 to Stieler; 6,568,714 to Stripe; 6,412,826 to Kulevsky, et al; 6,378,908 to Walker, et al.; 6,113,151 to Beans; 5,711,549 to Beans; 5,707,087 to Ridenour et al; 5,516,157 to Williamson; 5,516,156 Williamson; 5,423,581 to Saylers; 4,114,930 to Perkins et al; and 3,689,111 to Osmun, all teach coupling devices for connecting tubing to a fitting assembly to prevent leaks in a fluid transport system. 
     It is essential that fluid transfer hoses such as those employed in fluid transfer assemblies on power steering pressure and return lines exhibit tight tolerances and high strength to prevent the fluid from leaking from the assembly. Current practice in the hose connector art requires that a heavy clamping or crimping force be applied about a collar around the hose and the fitting to provide a fluid-tight seal and to provide pull-off resistance to the assembly. In such cases, the hose is compressed radially inward to make a seal. However, it is difficult to make a leak-tight seal, because the tube, even though malleable, tends to have enough elasticity to relax and deform upon release of the clamping or crimping pressure sufficient to compromise the fluid-tight seal, particularly when the fluid is under high pressure for an extended period of time. Therefore, while conventional connectors generally are able to achieve the required tolerances or the strength required to provide good sealing and hose retention properties, these properties are generally accompanied by undesirable high assembly effort. For example, a fluid transfer assembly designed to achieve low push-on force throughout its dimensional tolerance, will have a high probability of poor to mediocre coupling tensile, burst and impulse performance. 
     Accordingly, it would be advantageous to provide a hose endform connector that would increase coupling retention using both clamped and crimped assembly design while requiring reduced assembly effort force. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a hose coupling endform having improved coupling retention and sealing properties with no effect on assembly effort. 
     It is another object of the invention to provide a method of assembling a hose endform connector to a hose whereby coupling retention is improved and assembly effort is unaffected. 
     In accordance with the present invention, a hose endform connector is described for use in connecting a fluid transfer hose thereto in a manner which provides a leak-free fluid transfer assembly having increased coupling retention while not increasing the assembly effort force required in prior art hose endform connection assemblies. The hose endform connector comprises a rigid tubular member having a first end and a second end. The hose endform connector has a channel extending from the first end to the second end. The channel exhibits an inner diameter extending along its longitudinal axis for transporting a fluid therethrough. The rigid tubular member further comprises a stem portion defining the first end of the rigid tubular member. The stem portion has a uniform annular outer surface diameter extending a predetermined distance from the end of the hose endform connector, wherein the uniform annular surface is adapted to be inserted into an open ended channel of a hose. The stem portion further includes at least one sealing member extending outward from the outer surface diameter of the stem portion in a direction toward the second end to form a radially increasing surface having a tapered profile. The tapered surface terminates in an outward rim having an asymmetrical shape. The opposite side of the tapered surface of the sealing means exhibits an annular surface which is perpendicular or near perpendicular to the rigid tubular member. The asymmetric shape of the outer perimeter of the sealing member increases coupling tensile (axial force) by as much as 92% leaving assembly effort unaffected. 
     The second end portion includes a tubular structure which may include an annular ridge or ring suitable for connecting the second end to another tubular structure, such as by a quick-connect/disconnect device. 
     In accordance with the present invention, the metal fitting is loosely inserted into the open end of the hose where it is joined to the tube in a fluid-tight seal created by crimping, swaging, rolling or other means of securing the hose around the metal barbed fitting. The fluid-tight seal is created by the high pressure of the metal annular barbs pressed against the inner diameter of the hose. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a longitudinal side view of an endform tube connector of the present invention ready for assembly with a hose; 
         FIG. 2A  is a cross-sectional end view of the endform tube connector taken along line  1 - 1  of  FIG. 1 . 
         FIG. 2B  is a cross-sectional end view of an endform tube connector taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3A  is a graph illustrating the coupling tensile force of an endform connector of the present invention. 
         FIG. 3B  is a graph illustrating the coupling tensile fore of an endform connector of the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It has been found that a hose endform connector having an arrowhead barb configured to exhibit an asymmetric perimeter rather than a symmetric circular perimeter provides significantly improved tensile values. Furthermore the asymmetric barb exhibits significantly less sensitivity (more robust) to crimp diameter variability, hose dimensional variability, etc., while maintaining an overall equivalent performance with respect to both inside and outside diameters of the hose to which the coupler is assembled as well as exhibiting no increase in push-on force in assembling the endform connector to a hose. 
     The basic concept of the present invention is to change the shape of the outer perimeter of the arrowhead barb from a symmetrical circular shape to an asymmetric shape by offsetting the shape of the arrowhead barb and creating a larger interference between the stem land diameter and the arrowhead barb diameter. More specifically, the coupling retention is increased using both clamped and crimped assembly design formats, while maintaining equivalent assembly effort force. 
     The advantage of the asymmetric arrowhead barb design over the conventional symmetrical circular arrowhead barb is as follows:
         push-on force is not increased.   Coupling tensile (axial force) is enhanced up to about 92%.   Peak coupling tensile (axial force) is maintained over a wider tolerance.       

     The potential applications for the endform connectors having the asymmetrical configuration of the present invention include assemblies for automotive and other mechanical applications, such as in power steering, transmission, oil cooler, and other fluid transport assemblies requiring high pressures. 
       FIGS. 1 ,  2 A and  2 B illustrate a hose endform connector of the present invention used to connect an end form connector to a polymeric hose. As shown in  FIG. 1  the endform connector  10  includes a tubular body  12  having a first end  14  and a second end  16 . A channel  18  extends along longitudinal axis X from the first end  14  to the second end  16 . The tubular body  12  includes a stem portion  20  and a sealing member  22  adjacent the first end  14  of the tubular body  12 . The stem portion  20  and the sealing member  22  are adapted to be inserted into an open channel  24  of a hose  26  to secure the hose  26  to the endform connector  10  to provide a leak-free connection. The stem portion  20  has a uniform outer annular surface  28  extending a fixed distance from the first end  14  of the tubular body  12 . The sealing member  22  extends radially outward from the outer annular surface  28  of the stem portion  20  to form a radially increasing surface  30  having a tapered profile. The radially increasing surface  30  of the sealing member  22  terminates in a rim  32  exhibiting an asymmetrical perimeter. The sealing member  22  includes a rearward surface  34  lying in a plane perpendicular to or nearly perpendicular to the orientation of the tubular body  12 . The rearward surface  34  of the sealing member  22  extends radially outward from the tubular body  12  and terminates with the rim  32  exhibiting an asymmetric perimeter. Typically, the rearward surface  34  may be tapered at an angle θ of up to about 5°, preferably, about 0 to 3° and most preferably, about 0 to 2°, with respect to the vertical orientation of the rearward surface  34 . The stem portion  20  is adapted to be inserted into an open end  24  of a hose  26  to provide a leak-free fitting.  FIG. 2A  shows a cross-sectional view of the endform connector of  FIG. 1  along line  1 - 1 , wherein the rim  32  of the sealing member  22  is shown as having an asymmetric configuration while the channel  18  of the tubular body has a circular configuration.  FIG. 2B  shows a cross-sectional view of the stem portion  20  of the connector  10  connected to a hose  26  along line  2 - 2  of  FIG. 1 . 
     When the endform connector  10  is inserted into the open end of the hose  26 , sufficient pressure is exerted upon the hose  26  to radially compress the hose  26  inward around the stem portion  20  of the end fitting  10  such that the open channel  24  of the hose  26  engages the sealing member  22  providing a leak-free seal in the fuel transport assembly. The sealing members  22  not only provide leak-free seals but they also increase or maintain the pull-off resistance of the hose  26  from the endform connector  10 . 
     The number of sealing members on the endform connector is not critical. One sealing member in the form of an arrowhead barb is sufficient in most applications; however, it may be desirable to include more than one sealing member at fixed intervals along the stem portion of the endform connector. In those instances where more than one sealing member is employed, It may be desirable to alter the rotational position of the more than one sealing members to exhibit a non-linear orientation of the asymmetrical rims so that the symmetry of the more than one arrowhead barbs are not in a linear relationship. 
     The materials used to form the endform connector should be of a low corrosion tolerance material. In one embodiment the endform connector is formed from a metal, such as steel or the like, or it is formed from a ceramic material or a rigid plastic. Such materials should be high quality and free from voids, pits, laps, cracks, folds, seams and other defects. It is within the context of the present invention to treat the metal or ceramic endform connectors, especially the arrowhead barbs, to protect them from the environment. The endform members may be coated with a polymeric material  36  ( FIG. 1 ) such as nylon, or it may be electroplated, painted or similarly treated. In another embodiment, the endform may be formed completely from a plastic material. 
     Example 1 
     SAMPLE 1—A first endform connector having an asymmetric shaped arrowhead barb in accordance with the present invention, and a fluid transport hose were assembled to determine coupling tensile values, robust characteristics, and push-on force. 
     COMPARATIVE SAMPLE 2—A second endform connector having a circular shaped arrowhead barb in accordance with the prior art, and a fluid transport hose were assembled to determine coupling tensile, robust characteristics, and push-on force. 
     Regarding SAMPLE 1, the prediction trace yields the following insight with respect to coupling tensile performance:
         Hose 3209 yields higher tensile values than hose 3039.   Coupling tensile values drop as hose ID increases.   Coupling tensile values drop significantly as the “% compression” of the crimped assembly decreases.   Asymmetrical stem and symmetric stem yield approximately equal tensile values at high compression.   Symmetric barb is very sensitive to crimp compression as evidenced by the slope of the “% compression” factor traces.       

     Regarding SAMPLE 2, the prediction trace yields the following insight with regard to the asymmetric coupling tensile performance:
         Overall equivalent performance of each stem with respect to the following factors: Hose, OD, and ID.   The slope of the “% compression” factor is near zero, indicating that the asymmetric stem is much less sensitive (more robust) to crimp diameter variability, hose dimensional variability, etc.       

     Although the present invention has been fully described in connection with a preferred embodiment thereof and with reference to the accompanying drawings, various changes and modifications will occur to those skilled in the art. Accordingly, such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.