Abstract:
A sectionalized rocker arm cover assembly ( 10 ) is utilized for diesel engine ( 14 ) applications having overhead high pressure fuel lines ( 26 ). The fuel lines ( 26 ) connect to fuel injectors ( 20 ) that protrude through a primary member ( 16 ) of the rocker arm cover assembly ( 10 ). The rocker arm cover assembly ( 10 ) is sectionalized longitudinally. Sectionalizing the cover assembly ( 10 ) obviates the need to dismantle the fuel lines ( 26 ) and permits easy access to service the rocker arms ( 29 ). The injectors ( 20 ) are disposed longitudinally and provide vertical support to the rocker arm cover assembly ( 10 ).

Description:
TECHNICAL FIELD 
     This invention relates to a combustion engine rocker arm cover assembly and more particularly to a sectionalized rocker arm cover assembly with protruding fuel injectors. 
     BACKGROUND OF THE INVENTION 
     Rocker arm covers are commonly utilized for combustion engine applications. The covers arc engaged sealably over a cylinder head of a combustion engine thereby protecting a series of rocker arms. The covers not only protect the rocker arms, but assure that oil, which sprays about and lubricates the rocker arms and surrounding mechanisms, remains within the engine cylinder head. The rocker arm cover typically is of a one piece construction having a resilient seal placed between the engine cylinder head and the rocker arm cover. 
     The high-pressure fuel injection system of a diesel combustion engine has a unique configuration compared to that of a gasoline engine. The high-pressure fuel injectors are commonly placed above and parallel to each combustion cylinder and can be accessed after removal of the rocker arm cover. The fuel injectors are fed by high-pressure fuel lines which penetrate a side of the engine cylinder head and engage the fuel injectors perpendicularly at mid-length. This engagement produces numerous problems. First, unwanted lateral stresses are placed upon the injectors which hinder reliability of radially extending injector seals. Second, fuel leakage at the injector connection is not easily detectable. Any leaking fuel can mix with the lubricating oil thereby compounding problems with engine operation. 
     To resolve these concerns, current interest is to extend the diesel fuel injectors up through the rocker arm cover. Fuel can then be fed to the injectors from a protruding injector end disposed above the rocker arm cover. The high-pressure fuel line connection to the injector is more reliable than the mid-length connection. And, any chance occurrence of fuel leakage is isolated from the engine oil and is easily detectable. Unfortunately, the high-pressure fuel lines must extend over the rocker arm cover to feed the fuel injectors. In order to service the rocker arms or mechanisms beneath the rocker arm cover, the high-pressure fuel lines must be dismantled prior to removing the rocker arm cover. 
     SUMMARY OF THE INVENTION 
     The invention provides a sectionalized rocker arm cover assembly having a primary member, a secondary member, a plurality of fuel injectors and a plurality of respective high pressure fuel feed lines. The primary member has a primary brim sealingly connectable to a cylinder head of a combustion engine. Each fuel injector protrudes through an orifice of the primary member. The orifices align longitudinally along the primary member length. Substantially extending longitudinally along the primary member is a primary edge. The primary edge engages sealably to a secondary edge of the secondary member. The secondary member also has a secondary brim sealingly connectable to the cylinder head of the diesel engine. A plurality of high pressure fuel lines extend over the secondary member and connect to a fuel feed end of each fuel injector disposed above the primary member. 
     Preferably, each orifice of the primary member is defined by an upper edge, a lower edge, and an intermediate surface. The intermediate surface interposes and is defined by the upper and lower edges. Each fuel injector preferably has an extension portion attached beneath the fuel feed end. The extension portion has a shelf facing upward. The cross sectional area of the fuel feed end is smaller than the cross sectional area of the extension portion, the difference amounting to the surface area of the shelf. The shelf contacts the intermediate surface surrounding the primary member orifice. This contact provides vertical support to the primary member thereby providing a reliable seal along the primary and secondary edge of the respective primary and secondary members without the addition of further fasteners. Adequate clearance is provided between the secondary member and the rocker arm mechanisms so that the secondary member can disengage and slide out from beneath the assembled high pressure fuel lines for maintenance of the rocker arms. 
     Thus, an advantage of the present invention is a reliable seal along the primary and secondary edges. 
     Another advantage of the present invention is facilitating access below the rocker arm cover without having to dismantle the fuel injection system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is now made to the accompanying drawings, in which: 
     FIG. 1 is a partial perspective view of a combustion engine having a sectionalized rocker arm cover assembly in accordance with the invention; 
     FIG. 2 is a cross-sectional view of the sectionalized rocker arm cover assembly taken along line  2 — 2  as shown in FIG. 1; 
     FIG. 3 is an enlarged cross-sectional view of a primary edge connected to a secondary edge; 
     FIG. 4 is an enlarged cross-sectional exploded view of a fuel injector extending through an orifice of the primary member; 
     FIG. 5 is an exploded perspective view of a primary seal, a secondary seal, and an interposing seal; and 
     FIG. 6 is an exploded perspective view of a second embodiment of the sectionalized rocker arm cover assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1 of the drawings, a sectionalized rocker arm cover assembly  10  interconnects to a cylinder head  12  of a combustion engine  14  having cylinders  15 , generally from above. The interconnections of the rocker arm cover assembly  10  seal to prevent engine oil leakage and to attenuate engine noise. A primary member  16  connects longitudinally to a secondary member  18  of the sectionalized rocker arm cover assembly  10 . 
     A plurality of fuel injectors  20  is substantially disposed perpendicularly beneath the primary member  16  of the rocker arm cover assembly  10 . Each fuel injector  20  has a lower end  17  and an upper fuel feed end  22 . Each lower end  17  protrudes into the respective cylinder  15  from above, and each fuel feed end  22  protrudes through a respective orifice  24  of the primary member  16  from below. The plurality of orifices  24  generally align along the primary member  16  longitude. Each fuel feed end  22  connects to a high pressure fuel line  26  which routes over the secondary member  18  to a fuel manifold  28  generally located beneath the rocker arm cover assembly  10  and along the combustion engine  14  side. Preferably, fuel manifold  28  is above, as opposed to below, an air-intake manifold  30 . Placement of the fuel manifold  28  is away from, or opposite, the hot exhaust manifold of the combustion engine  14  to prevent premature heating of the fuel. The secondary member  18  is sufficiently shallow wherein secondary member  18  can slide out from beneath the fuel feed lines  26  after disengagement from the combustion engine  14  without having to disassemble the high pressure fuel system. 
     Referring to FIG. 2, the secondary member  18  is generally disposed above a series of rocker arms  29  and associated rocker arm shaft  31 , and cam  33 . A primary brim  32  of primary member  16  interconnects to cylinder head  12 . A primary edge  34  of primary member  16  engages a secondary edge  36  of the secondary member  18 . A secondary brim  38  of secondary member  18  interconnects to the cylinder head  12 . In assembly, the primary brim  26  is substantially planar to the secondary brim  32 . The secondary brim  38  has a trailing end portion  40  as shown in FIG. 1 which may or may not be planar to the primary brim  32 . The restriction is that a lineal distance  42 , generally measuring from the trailing end portion  40  bottom to the secondary member  18  top, must be substantially less than a lineal distance  44 , generally measuring vertically from the fuel feed lines  26  bottom to the highest combustion engine  14  projection disposed beneath the secondary member  18 . 
     Preferably, primary brim  32 , secondary brim  38 , and trailing end portion  40  of the secondary brim  38  are all planar to one-another for ease of manufacturing and assembly. To assure lineal distance  42  is substantially less than lineal distance  44 , the sectionalized rocker arm cover  10  has a shoulder  46  interposing beneath the primary and secondary members  16 ,  18 , and above the cylinder head  12 . The shoulder  46  periphery generally aligns beneath the primary and secondary brims  32 ,  28 . The shoulder  46  height is substantially parallel to fuel injectors  20  and serves to reduce the lineal distance  42  to the required clearance amount. Shoulder  46  is secured to the cylinder head  12  via a plurality of standard threaded fasteners  47 . The primary and secondary members  16 ,  18  are connected to the shoulder  46  via a plurality of standard threaded fasteners  49  as shown in FIG.  1 . 
     With the presence of shoulder  46 , the primary and secondary brims  32 ,  38  each have respective two-ends  54 ,  56 . Wherein, the two ends  54  of the primary brim  32  engage to the two ends  56  of the secondary brim  38  as shown in FIG.  1 . The primary edge  34  extends between the two ends  54  and the secondary edge  34  extends between the two ends  56  of the secondary member  18 . A top surface  48  of shoulder  46  is substantially perpendicular to fuel injectors  20  and preferably has a continuous peripheral groove  58  to receive a primary seal  50  and a secondary seal  52 . The primary seal  50  seals between the shoulder  46  and the primary brim  32  of primary member  16 ; and the secondary seal  52  seals between the shoulder  46  and the secondary brim  38  of secondary member  18 . An interposing seal  60  seals between the primary edge  34  and the secondary edge  36 . 
     Referring to FIG. 3, the primary edge  34  has an upper rib  62  and a lower rib  64 . The ribs  62 ,  64  extend longitudinally along the primary edge  34  between the two primary ends  54 . Disposed between ribs  62 ,  64  is the interposing seal  60 . Secondary edge  36  has a nubbin  66  which extends longitudinally along the secondary edge  36  between the two secondary ends  56 . Also extending longitudinally at the nubbin  66  apex is a channel  68 . The interposing seal  60  seats between the ribs  62 ,  64  and within the channel  68  of nubbin  66 . To add rigidity along the length of interposing seal  60 , the secondary edge  36  has a raised longitudinally extending lip  70 . Lip  70  is generally perpendicular to the fuel injectors  20 . The bottom side of lip  70  engages the top side of upper rib  62  thereby providing rigidity support. 
     Referring to FIG. 4, each orifice  24  of the primary member  16  is circumscribed by an intermediate surface  72  generally facing downward. Contacting the intermediate surface  72  from below is a shelf  74  of the fuel injector  20 . This contact provides longitudinal rigidity to the primary member  16  which assures sealant reliability of interposing seal  60  without the need for fasteners along the primary member  16  longitude. The intermediate surface  72  is substantially perpendicular to the fuel injector  20  longitude. Furthermore, intermediate surface  72  is disposed between and defined by an upper edge  76  and a lower edge  78 . The intermediate surface  72 , the upper edge  76 , and the lower edge  78  circumvent and define the orifice  24  of primary member  16 . 
     Attaching rigidly beneath the fuel feed end  22  of fuel injector  20  is an extension portion  80  which forms an upward facing shelf  74 . The fuel feed end  22  periphery and the extension portion  80  periphery define the shape and area of shelf  74 . The shelf  74  is substantially parallel to the intermediate surface  72 . The cross sectional area of the fuel feed end  22  taken along the longitude of the fuel injector  20  is less than the cross sectional area of the extension portion  80  taken along the same longitude. The difference in cross sectional area amounts to the surface area of the shelf  74 . This difference in area also enables placement of the primary member  16  over the pre-installed fuel injectors  20  during assembly. 
     Although the longitudinal contour of fuel feed end  22  and the extension portion  80  may be of any variety of shapes, the contour is preferably cylindrical. Furthermore, extension portion  80 , the fuel feed end  22 , intermediate surface  72 , upper edge  76  and lower edge  78  are concentric. The orifice  24  is therefore circular, and the intermediate surface  72  and shelf  74  are annular. The upper edge  76  diameter is substantially less than the lower edge  78  diameter. Extension portion  80  further has an extension portion cylindrical wall  82  which opposes lower edge  78 . Shelf  74  is disposed radially between and is defined by the extension portion cylindrical wall  82  and a fuel feed end cylindrical wall  84  which opposes upper edge  76 . The fuel feed end and extension portion cylindrical walls  84 ,  82  are concentric to each other and generally perpendicular to the shelf  74 . 
     Within lower edge  78  and in communication with orifice  24  is a peripheral groove  86  which seats a seal  88 . Seal  88  preferable is an O-ring, which resiliently engages between the extension portion cylindrical wall  82  of injector  20  and the lower edge  78  of primary member  16 . 
     Referring to FIG. 5, the primary seal  50  is generally planar to the secondary seal  52 . The ends of interposing seal  60  are generally perpendicular to the primary and secondary seals  50 ,  52 . The primary seal  50  and the secondary seal  52  can be molded as one unitary continuous seal. In the alternatives, the secondary seal  52  and the interposing seal  60  can be molded as one unitary continuous seal wherein the molded ends form right angles, or, all three seals  50 ,  52 ,  60  can be molded as one unitary seal wherein the molded ends form a T-joint. 
     Referring to FIG. 6, a second embodiment is shown wherein the numeral two, “2,” has been added as a prefix to like elements between the first and second embodiments. The primary member  16  is integral and unitary to the shoulder  46  of the first embodiment, thereby forming an alcove member  290 . The alcove member  290  is beneficial in the sense that the primary and secondary seals  50 ,  52  are no longer required. In addition, the fasteners  49  which engage the primary member  16  to the shoulder  46  are no longer required. The secondary member  218 , however, is still required along with the interposing seal  260 . The interposing seal  260  is continuous and a plurality of fasteners  249  are required to hold secondary member  218  to the alcove member  290 . 
     The shoulder  46 , the primary member  16  and the secondary member  18  may be made of aluminum, steel, or plastic. For strength and weight considerations, larger diesel applications utilize aluminum. For smaller engine applications which utilize the second embodiment, injection molded plastic may be an ideal material for weight and ease of manufacturing considerations. 
     Although the preferred embodiments of the present invention have been disclosed, various changes and modifications may be made thereto by one skilled in the art without departing from the scope and spirit of the invention as set forth in the appended claims. It is also understood that the terms used herein are merely descriptive, rather than limiting, and that various changes in terminology may be made without departing from the scope and spirit of the invention.