Patent Publication Number: US-8967110-B2

Title: Engine front cover with rotational support insert

Description:
FIELD 
     The present disclosure relates to an engine assembly, and more particularly, to an engine front or rear cover made from plastic and having a molded-in metal insert defining a bore for receiving a rotating engine component. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Currently, engine covers (front or rear) are produced from aluminum castings or steel stampings. The aluminum castings provide a flexibility in design, but the cost and mass of aluminum are significant and it is desirable to use a significantly lower mass component. 
     SUMMARY 
     The present disclosure is directed to an engine front cover assembly including a plastic engine cover. A metal insert is secured within the plastic engine cover and defines a bore configured to receive a rotating engine component. A seal is located in a seal seat defined within the bore of the metal insert and configured to sealingly engage the rotating engine component. The metal insert can include a radially extending flange portion defining reinforcing ribs that are overmolded by plastic reinforcing ribs of the plastic engine cover. The flange portion can be a mesh or textured surface to provide enhanced surface area contact between the plastic front cover and the metal insert. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a perspective view of an engine front cover assembly according to the principles of the present disclosure; 
         FIG. 2  is a close-up perspective view of the engine front cover illustrating the metal insert overmolded within the plastic front cover; 
         FIG. 3  is a cross-sectional view of the engine front cover taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the engine front cover taken along line  4 - 4  of  FIG. 2  and further illustrating an optional mesh pattern of the flange portion of the metal insert; 
         FIG. 5   a - 5   c  illustrate alternative surface patterns of the flange portion of the metal insert; and 
         FIG. 6  is a cross-sectional view of the engine cover including mounting holes incorporated into the metal insert. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     With reference to  FIGS. 1-5 , the plastic engine front cover assembly  10  according to the principles of the present disclosure will now be described. The engine front cover assembly  10  includes a plastic engine cover  12  defining an aperture  14  configured to receive a rotating engine component  16  such as a crankshaft, camshaft, or idler shaft, therethrough. A metal insert  18  is secured within the plastic engine cover and defines a seal bore  20  configured to receive the rotating engine component  16 . A seal  22  is located within a seal seat  24  defined within the seal bore  20  of the metal insert  18  and configured to sealingly engage the rotating engine component  16 . 
     Even though the plastic materials have performance characteristics approximately equivalent to aluminum, obtaining tolerances around the crank seal is very difficult. To resolve this, the crankshaft center is set as the datum point and the metal insert  18  with the shaft seal seat  24  is overmolded at the centered location creating a final dimensionally correct part that is lighter in weight than conventional steel or aluminum engine covers. Should there be additional adjustments, the metal insert  18  can be machined to requirements. 
     The metal insert  18  can be overmolded within the plastic engine cover  12 . The plastic engine cover  12  is configured to fit over an end of an engine block  26  and can include a plurality of mounting apertures  28  for mounting the cover  12  to the engine block  26  and/or other components of the engine assembly such as the cylinder heads, and intake manifolds and oil pans, if desired. The plastic engine cover  12  can also include additional apertures  30  to receive additional pulley hubs/tensions and cam shafts. The plastic engine cover  12  can also include a plurality of intersecting reinforcing ribs  32  on at least one face  34  thereof. The reinforcing ribs  32  can intersect with annular ribs  36  that can surround the mounting apertures  28  as well as the aperture  14  and additional apertures  30 , as shown in  FIGS. 1 and 2 . It is noted that in  FIG. 1  only a portion of the detail of the reinforcing ribs  32  and  36  are shown for simplicity, while it should be understood that the reinforcing ribs  32 ,  36  are intended to extend along the entire surface of the cover  10 . 
     With reference to  FIGS. 2-4 , the metal insert  18  can include a generally planar wall portion  40  defining the circular bore  20  therein. An annular wall portion  42  extends axially from the planar wall portion  40  and is coaxial with the bore  20  for defining the seal seat  24 , wherein the seal  22  seats against the annular wall portion  42  and the planar wall portion  40 . A plurality of radially extending reinforcing ribs  46  can extend radially outward from the annular wall portion  42  in a spoke-like fashion and terminate at a second annular wall portion  48 . Additional reinforcing ribs  50  can extend radially outward from the second annular wall portion  48  and can be overmolded by the reinforcing ribs  32  of the plastic engine cover  12 , as best shown in  FIG. 3 . A section  44  of the planar wall portion  40  can optionally be provided with a mesh-like portion defining holes  60  ( FIG. 5A ) or waffle-type recesses  62  ( FIG. 5B ) or other surface irregularities  64  ( FIG. 5C ) that are overmolded by the plastic engine cover  12  and therefore provide additional surface area contact between the metal insert  18  and the plastic engine cover  12 . 
     With reference to  FIG. 6 , the planar wall portion  40  of the metal insert  18  can extend laterally or vertically to encompass mounting apertures  28  on opposites sides of the seal bore  20  to help to stabilize the position of the seal  22  in the as-built condition as the plastic expands and contracts with temperature variations. As the cover heats up, the metal insert  18  holds the seal  22  in its proper position with the perimeter bolt bosses  28 . According to one embodiment, the metal insert can extend a sufficient distance to encompass at least a pair of bolt bosses  28  on opposite sides of the seal bore  20 . 
     The additional reinforcing ribs  50  of the metal insert  18  can have a height of 30-70% of the final overmolded rib height. The ribs  50  of the metal insert  18  can have a thickness of 30-60% of the final overmolded rib thickness, and more preferably 40-50% of the final overmolded rib thickness. The length of the reinforcing ribs can be at least 25 mm and up to approximately 75 mm long. The thickness of the planar section  44 A of the flange portion  44  can be between 0.75 and 2 mm. The size of the holes in the mesh or the recesses in the waffle-like pattern can be from 0.5 to 3.2 mm, and more preferably, 1-2 mm in diameter. The insert  18  can be made from brass, aluminum, steel, magnesium, pressed metal, or other materials. The plastic front engine cover  12  can be made from high performance thermoplastic or thermoset resins enhanced with fiberglass or other filler types at levels of from 30-60%. Also, the material should be able to withstand continuous temperatures of 130° C.