Patent Publication Number: US-2005140095-A1

Title: Insert molded structure and method for the manufacture thereof

Description:
This application claims priority from Canadian Patent application No. 2,454,283 filed Dec. 29, 2003.  
     FIELD OF THE INVENTION  
      This invention relates to insert molded structures and methods for the manufacture thereof, and in particular to structures where inserts are encapsulated, at least partially, in a molded material.  
     BACKGROUND OF THE INVENTION  
      U.S. Patent No. 4,214,781 to Joseph discloses a pipe joint in which an end portion of a metal pipe is inserted into an aperture in a molded housing. The end portion of the metal pipe has an annular rib, and an O-ring seal is located between the annular rib and the housing. A metal eyelet is molded into the molded housing and is swaged over the rib to hold the O-ring in compression. A difficulty with such structures, however, is that it is difficult to get a good leak-proof joint by such swaging methods.  
     SUMMARY OF THE INVENTION  
      The present invention provides an improved insert molded structure in which an insert member and a surrounding wall are maintained in substantially fluid-tight sealing relationship.  
      In accordance with one aspect of the present invention there is provided an insert molded structure comprising an insert member having an inner end portion, a compressed O-ring seal mounted on said inner end portion, and a wall formed of a molded material which partially encapsulates the O-ring seal and said inner end portion and which maintains the O-ring seal in compression.  
      In accordance with a further aspect of the present invention there is provided a method of attaching an insert member to a wall, comprising the steps of providing an insert member having an inner end portion, mounting an O-ring seal on said inner end portion, and forming the wall by molding material around the O-ring seal to partially encapsulate and compress the O-ring seal and maintain the O-ring seal in compression. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In order that the invention may be more clearly understood and more readily carried into effect the same will now, by way of example, be more fully described with reference to the accompanying drawings in which:  
       FIG. 1  is an elevational view, partly in cross-section, of an insert molded structure according to a preferred embodiment of the present invention;  
       FIG. 2  is a top plan view of the insert molded structure taken in the direction of arrow A in  FIG. 1 ;  
       FIG. 3  is a side view of the insert molded structure taken in the direction of arrow B in  FIG. 1 ;  
       FIG. 4  is a view on an enlarged scale of one of the tubular members incorporated in the insert molded structure shown in  FIG. 1 ;  
       FIG. 5  is a view of an insert molded structure according to an alternative embodiment of the present invention; and  
       FIG. 6  is a view of an insert molded structure according to a further alternative embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      Referring to FIGS.  1  to  4 , inclusive, of the drawings,  10  denotes generally an insert molded structure which comprises four insert members constituted by tubular members, namely, an inlet feed oil tube  11 , an outlet feed oil tube  12 , an inlet return oil tube  13 , and an outlet return oil tube  14 . These tubes  11 ,  12 ,  13  and  14  are of identical form in the preferred embodiments shown in the drawings. As is most clearly shown in  FIG. 4 , each tube  11 ,  12 ,  13  and  14  has an inner end portion  15  which is provided at the distal end thereof with a radially outwardly projecting flange or rib  16  and another radially outwardly projecting rib  17  longitudinally spaced from rib  16 . An O-ring seal  18  is mounted on the inner end portion  15  between the ribs  16  and  17 . The inner end portion  15  is also preferably formed with at least one further radially outwardly projecting rib  19  which is longitudinally spaced from ribs  16  and  17 . The form and dimensions of rib  19  may correspond to those of rib  17 , thereby to provide a groove  44  between the rib  19  and the rib  17 . In the preferred embodiments shown in the drawings, the outer end portion of each tube  11 ,  12 ,  13  and  14  is formed with an annular bulbous portion  20  to facilitate mounting thereto an end portion of, for example, an oil line  24 ,  25 ,  27  and  28 , respectively. While as shown in the drawings, the tubes  11 ,  12 ,  13  and  14  are of circular form in transverse cross-section, it will be appreciated that these tubes  11 ,  12 ,  13  and  14 , or at least portions of them, could be of other form such as, for example, hexagonal form in transverse cross-section.  
      With further reference to  FIGS. 1, 2  and  3 ,  21  denotes generally a housing which is formed of a moldable material such as a plastic material which may be a thermoplastic or a thermosetting material and which may contain reinforcement such as glass fibre or particulate reinforcement. The tubes  11 ,  12 ,  13  and  14 , which are preferably of metal such as, for example, aluminum, steel, brass or copper alloy, are usually made of a material having a different coefficient of thermal expansion than the material of the housing  21 . The housing  21  is formed with a wall which, in the preferred embodiments shown in the drawings, is constituted by a socket  22  for the inner end portion  15  of each of the tubes  11 ,  12 ,  13  and  14 . The housing  21  is formed by injection molding the moldable material with the molded material in each socket  22  partially encapsulating the O-ring seal  18  in that the O-ring seal  18  is a snug fit in the groove between the ribs  16  and  17  with the molded material in contact with the outer peripheral face of the O-ring seal  18 . The molded material also encapsulates the inner end portion  15  of the respective tube  11 ,  12 ,  13  and  14  including the rib  19  although, for example, the radially outward portion of this rib  19  could be exposed so that this rib  19  is only partially encapsulated by the molded material. The moldable material is injection molded at a pressure which results in the moldable material radially compressing the O-ring seal  18 . During cooling and resultant shrinking of the moldable material, the compression of the O-ring seal  18  is partially relieved and the O-ring seal  18  expands, but the O-ring seal  18  remains, once the moldable material has fully cooled, under sufficient compression as to provide a substantially fluid-tight seal between the inner end portion  15  of each tube  11 ,  12 ,  13  and  14  and the respective socket  22  of the housing  21 . The further radially outwardly projecting rib  19  of the inner end portion  15  of each tube  11 ,  12 ,  13  and  14  is also encapsulated by the molded material of the respective socket  22  of the housing  21  mechanically to secure the inner end portion  15  of each tube  11 ,  12 ,  13  and  14  to the respective socket  22  of the housing  21 . The encapsulation of the rib  19  of the inner end portion  15  of each tube  11 , 12 ,  13  and  14  by the molded material of the respective socket  22  of the housing  21  also has the beneficial effect of providing a relatively long and tortuous leak path for any fluid which tries to leak past the O-ring seal  18 .  
      By the use of appropriate core molds during the injection molding of the housing  21 , this housing  21  is formed with a hollow interior  23  within which may be provided a bypass valve  29 . Bypass valve  29  is described further in U.S. Pat. No. 6,253,837 (Seiler et al.), which is herein incorporated by reference. The inlet feed oil tube  11  may be operatively connected by the feed oil line  24  to, for example, a heat exchanger (not shown) in which the oil, for example transmission oil, may have been cooled. The outlet feed oil tube  12  may be operatively connected by the feed oil line  25  to an automotive engine denoted by the reference numeral  26 . The engine  26  may be connected by the return oil line  27  to the inlet return oil tube  13 , and the outlet return oil tube  14  may be connected by the return oil line  28  to the heat exchanger for cooling of the oil. Different materials may, of course, be used for the tubes  11 ,  12 ,  13  and  14  and for the housing  21  where different oils or other fluids are used with insert molded structure  10 .  
      Under normal operating conditions of the engine  26 , the inlet feed oil tube  11  is in communication through the housing  21  with the outlet feed oil tube  12 , and the inlet return oil tube  13  is in communication through the housing  21  with the outlet return oil tube  14  so that oil may flow from the heat exchanger to the engine  26  and back from the engine  26  to the heat exchanger. During this normal operation of the engine  26 , bypass valve  29  is in contact with a valve seat  30  in the housing  21  thereby preventing communication through the housing  21  between the return oil tubes  13 ,  14  and the feed oil tubes  11 ,  12 . However, during, for example, start-up of the engine when the return oil does not require cooling, the bypass valve  29  is activated thereby, moving the bypass valve member  29  under the influence of spring  31  and against the influence of spring  32  away from the valve seat  30  (as shown in  FIG. 1 ), so that oil may pass through the housing  21  from the inlet return oil tube  13  to the outlet feed oil tube  12 , thus bypassing the heat exchanger.  
      Although the materials of the tubes  11 ,  12 ,  13  and  14  and of the housing  21  usually have different coefficients of thermal expansion, radial expansion of the O-ring seals  18  as the compression thereof is partially relieved ensures that, throughout the operative temperature range and the operative pressure range of the oil, there is provided a substantially fluid-tight seal between the inner end portion  15  of each tube  11 ,  12 ,  13  and  14  and the respective socket  22  of the housing  21 .  
      While in the preferred embodiment of the invention hereinbefore described with reference to FIGS.  1  to  4 , inclusive, of the accompanying drawings, there are four tubular members, namely, the tubes  11 ,  12 ,  13  and  14 , together with the bypass valve  29  in the housing  21 , it will be understood that in alternative embodiments of the invention there may be only one or any number of tubular members attached to the housing by the method hereinbefore described, and there need not be any bypass valve within the housing.  
      Depending on the fluid, which instead of transmission fluid or oil, could for example, be engine oil, power steering oil, hydraulic oil, diesel fuel, gasoline, coolant or air, and depending on the intended use of the insert molded structure  10 , the temperature of the fluid may operatively vary over a considerable range of, for example, −40° C. to +260° C. Thus, for example, where the insert molded structure is a molded plastic tank manifold for a charge air cooler used on a turbocharged automotive engine, heated air provided to the tank manifold may be at a temperature of +260° C.  
      Referring now to the embodiment of the invention shown in  FIG. 5, 33  denotes an insert member constituted by a tubular member the form of which corresponds generally to the form of each of the tubes  11 ,  12 ,  13  and  14  with the same reference numerals being used to denote the parts of the tubular member  33  corresponding to the parts of each of the tubes  11 ,  12 ,  13  and  14 . It will be noted, however, that in the tubular member  33 , the inner end portion  15  of the tubular member  33  extends inwardly with an inner end  34  being angled. Furthermore, in the embodiment of  FIG. 5  the wall which in the embodiment hereinbefore described with reference to FIGS.  1  to  4 , inclusive, is constituted by each of the sockets  22  of the housing  21 , is instead constituted by a transition plate or wall  35  which is of moldable material and which may, for example, be of circular or square shape, the moldable material being injection molded partially to encapsulate an O-ring seal  36  corresponding to the O-ring seal  18 , with the O-ring seal  36  under radial compression, in a manner corresponding to that hereinbefore described with reference to FIGS.  1  to  4 , inclusive.  
      The transition wall  35  is provided with a peripheral land  37  which operatively abuts the peripheral portion of another wall  38  of, for example, a manifold surrounding an opening  39  in the wall  38 , the wall  38  being of a plastic material with the land  37  being jointed to the peripheral portion of the wall  38  by, for example, vibration, thermal or ultrasonic welding. As shown in  FIG. 5 , the inwardly extending end portion of the tubular member  33  may abut an opposed wall  40  of the manifold in order accurately to position the tubular member  33 . The transition plate or wall  35  may also be provided with an opposed peripheral land  41  so that, if desired the transition wall  35  may be joined to a further wall on the opposite side of the transition wall  35 .  
      The embodiment shown in  FIG. 6  differs from the embodiment hereinbefore described with reference to  FIG. 5  in that the insert member is constituted by a solid metal rod  42  in which is embedded a component such as, for example, a temperature sensor  43 . Alternatively, the insert member could, for example, be a tubular member the inner end of which is closed. For example, a temperature sensor may be disposed within the tubular member.  
      It will be appreciated that the rib  19  may be omitted. Furthermore, while in the embodiments of the invention as hereinbefore described with reference to the drawings the wall constituted by the sockets  22  of the housing  21  and the transition plate or wall  35  are described as being injection molded, this wall could, for example, be compression molded.