Abstract:
A cylinder head, air intake manifold, fuel injector and fuel rail arrangement for an overhead valve engine that provides a compact assembly. The fuel rail is attached to the cylinder head by fasteners that extend parallel to the fasteners that fix the intake manifold to an adjacent portion of the cylinder head. The layout is such, however, that there is no interference between the various components and thus accessibility is improved while cost is minimized.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an injected internal combustion engine and more particularly to an air manifold and fuel rail mounting arrangement for such engine. 
     The use of fuel injection in place of carburetors is being widely accepted in most applications for internal combustion engines. One convenient and relatively low-cost type of injection system employs what is referred to as “manifold injection.” With this type of arrangement, fuel is injected into the induction system preferably at a point quite close to the intake port of the engine. 
     With four-cycle engines, this generally means that the fuel injector is mounted in the cylinder head and injects fuel into the intake passage at a point that is located close to the intake valve seat and may, in fact, be directed directly toward that valve seat. This generally means that the fuel injector is mounted quite close to the area of attachment of the intake manifold to the cylinder head. This gives rise to certain problems in connection with the mounting of the various components to the cylinder head to ensure against interference between the various mounting arrangements. 
     It is, therefore, a principal object of this invention to provide an improved mounting arrangement for the components of a fuel injected, internal combustion engine. 
     It is a further object of this invention to provide an improved mounting arrangement for the components of a manifold injected engine where the fuel injectors spray into the cylinder head intake passages. 
     Frequently, it has been the practice to supply the fuel to the fuel injectors through a device that is referred to as a “fuel rail.” A fuel rail is actually a form of manifold that delivers fuel from a high pressure source to the individual fuel injectors. Many times, it has been the practice to mount the fuel rail directly to the injectors and not attach it permanently to any component of the engine other than through its hydraulic connections to the fuel supply system. However, this can give rise to the likelihood or possibility of the fuel rail working itself loose, particularly if the engine is subjected to vibrations in use. 
     It has, therefore, been proposed to fasten the fuel manifold or fuel rail also to the engine body on which the fuel injectors are mounted. This obviously gives rise to further problems in connection with attachment of the components including the fuel rail. 
     It is, therefore, a further object of this invention to provide an improved arrangement for attaching a fuel rail to an engine. 
     It is a still further object of this invention to provide an improved mounting arrangement for the fuel rail of a manifold injected engine where the fuel rail is mounted in close proximity to the intake manifold attachment to the cylinder head. 
     Because of the fact that the fuel injectors are disposed generally at an angle to the portion of the intake passage which they intersect, in order to provide the desired flow direction, then the normal positioning of the fuel rail is such that its hold-down fasteners extend at a different angle to the associated surface of the cylinder head than the fasteners that hold the intake manifold in place. This requires sequential machining operations and adds to the cost of manufacturing the various cylinder head assembly. 
     It is, therefore, a still further object of this invention to provide an improved arrangement for holding down the fuel rail and intake manifold to a cylinder head of an engine wherein the threaded fasteners for each can extend along parallel axis to simplify machining. 
     SUMMARY OF THE INVENTION 
     This invention is adapted to be embodied in a fuel injected internal combustion engine that is comprised of a cylinder head having a plurality of intake passages. An air intake manifold is attached to the cylinder head and supplies air to the intake passages of the cylinder head. A plurality of fuel injectors are mounted in the cylinder head and are positioned in proximity to the intake passages for spraying fuel directly into the intake passages. A fuel rail supplies fuel to these fuel injectors. The fuel rail is affixed to the cylinder head in proximity to the air intake manifold. The fuel rail is connected to the cylinder head by threaded fasteners that are disposed in the area between the fuel injector and the intake manifold so that the threaded fasteners for the fuel rail do not interfere with the attachment of the intake manifold to the cylinder head. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an end elevational view of the cylinder head and attached components of an internal combustion engine, with portions broken a way and shown in section. 
     FIG. 2 is a top plan view of the components shown in FIG. 1 but with the camshaft, cam cover and valve mechanism removed from the cylinder head. 
     FIG. 3 is an enlarged cross-sectional view taken along a plane parallel to the plane of FIG. 1 that passes through the axis of one of the cylinder bores of the engine. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the drawings, an internal combustion engine constructed in accordance with an embodiment of the invention is shown in part and is indicated generally by the reference numeral  11 . The engine  11  includes a cylinder head assembly  12  to which an air intake manifold assembly, indicated generally by the reference numeral  13  is affixed in a suitable manner. In addition, a fuel injection system, indicated generally by the reference numeral  14 , is affixed to the cylinder head assembly  12  adjacent the intake manifold  13  for injecting fuel into the induction system of the engine  12 . 
     Since the invention relates primarily to the relationship of the cylinder head, air intake manifold assembly  13  and fuel injection system  14 , an illustration of the cylinder block, crankshaft and other internal portions of the engine below the cylinder head assembly  12  is not believed to be necessary to permit those skilled in the art to practice the invention. Where any components of the overall engine  11  are not illustrated or described, any conventional or known structure may be employed. 
     The cylinder head assembly  12  is comprised of a main cylinder head casting  15  which may be cast from aluminum or aluminum alloy or any other suitable material. This casting  15  is formed in its lower face with recesses  16  (FIG. 3) that cooperate with the associated cylinder bores of the cylinder block and the pistons that reciprocate therein to form the combustion chamber to the engine  11 . 
     In the illustrated embodiment, the engine  11  is depicted as being of a four-cylinder inline type. It will be readily apparent to those skilled in the art, however, that the invention can be employed with engines having any number of cylinders and any desired cylinder arrangement such as V-type engines or the like. 
     The combustion chamber recesses  16  are formed in a planar lower surface  17  of the cylinder block casting  15  which surface is held in sealing arrangement with the associated cylinder block via threaded fasteners that pass through fastener receiving openings  18  formed in the cylinder head casting  15  in spaced relationship around the combustion chamber recesses  16 . 
     The cylinder head casting  15  is formed on one side (the right hand side in the illustrated embodiment) with an intake passage arrangement, indicated generally by the reference numeral  19 . In the specific example illustrated, the intake passage arrangement  19  is of the Siamese type for each cylinder having a common inlet opening  21  in an external surface  22  of the cylinder head casting  15 . This passage arrangement  19  divides into a pair of passage portions  23 , each of which terminates at a respective valve seat  24  in the cylinder head combustion chamber recess  16 . These valve seats  24  may be formed in any suitable manner, as by pressed or bonded seat inserts  25 . 
     Intake valves, which appear only partially in FIG.  3  and which reciprocate about an axes  26  that lie in a common plane control the opening and closing of the intake valve seats  24 . These intake valves are operated by a suitable mechanism, namely an overhead mounted intake camshaft  27  that has beating portions  28  that are journaled in bearing surfaces  29  machined directly in the cylinder head casting  15 . Bearing caps (not shown) are affixed to the cylinder head casting  15  by means of threaded fasteners that are received in tapped openings  31  formed on opposite sides of the bearing portions  29  as may be seen in FIGS. 2 and 3. As seen in FIG. 3, the rotational axis of the intake camshaft  28  is indicated at Ia in FIG.  2 . The valve axis line  26  intersects this axis. 
     Spark plugs (not shown) are mounted within spark plug wells  32  formed in the central portion of the cylinder head casting  15  and which define an axis  33  along which the received spark plug extends. This axis  33  is intersects substantially the center of the combustion chamber recess  16 . Thus, a spark plug received therein will have its gap disposed in this area so as to ensure complete charge burning throughout the entirety of each combustion chamber. 
     A pair of exhaust valve seats  34  are formed in each cylinder head recess  16  and form the inlets to exhaust passages  35  which extend therefrom to outlet openings in an exterior surface  36  of the cylinder head casting  15 . Like the intake passages  19 , the exhaust passages  35  for each cylinder are Siamesed. The exhaust valve seats  34  are formed, like the intake valve seats  24 , by suitable inserts  37  that are attached to the cylinder head casting  15  in a suitable manner. 
     Poppet type exhaust valves, which are not shown, are mounted in the cylinder head casting  15  in a suitable manner and reciprocate along respective exhaust valve axes  38 . These exhaust valve axes  38  lie in a common plane that is disposed at an acute angle α to plane containing the intake valve axes  26 . 
     The exhaust valves are operated by an exhaust camshaft  39  which is journaled in bearing surfaces  41  formed in the upper surface of the cylinder head casting  15 . The exhaust camshaft  39  has bearing portions  42  that are journaled in the surfaces  41  and which are retained in place by bearing caps (not shown). These bearing caps are affixed to the cylinder head casting  15  by threaded fasteners that are threaded into tapped openings  43  formed in the cylinder head casting  15 . 
     The intake camshaft  27  and exhaust camshaft  39  are driven by a suitable timing mechanism such as a chain, which is shown schematically in FIG.  2  and which is indicated by the reference numeral  44 . The exhaust camshaft rotational axis is indicated by the broken lines Ea in this Figure. 
     The intake camshaft  27  has cam lobes  45  that cooperate with thimble tappets (not shown) slidably supported within bores  46  formed in the cylinder head casting  15  for operating the intake valves in a well known manner. In a like manner, the exhaust camshaft  39  has cam lobes  47  that cooperate with thimble tappets (also not shown) received in bores  48  formed in the cylinder head casting  15 . As has been previously noted, the valve actuating mechanism may be of any known type and the foregoing description is merely exemplary. 
     Between the spark plug wells  32  at each end of the engine, there are provided a pair of clean-out openings  49  in the cylinder head casting  15 . This is to permit removal of core sand. These openings  49  are then closed by freeze plug as is well known in this art. 
     The valve actuating mechanism described is enclosed by a cam cover  51  that is affixed in a suitable manner to the cylinder head casting  15 . 
     The induction manifold  13  is served by an air inlet device which is not shown but which communicates with a throttle body  52  through an air supply duct  53 . The throttle body  53  contains one or more throttle valves that are operated remotely by the operator and which control the flow of air into a longitudinally extending plenum device  54 . 
     The plenum device  54  extends along one side of the engine and has a plurality of runner sections  55  emanating from it, one for each intake passage opening  21 . The runners  55  have a re-entrant curvature and terminate at their discharge ends in respective flange portions  56  that have a pair of lugs that receive threaded fasteners  57 . These fasteners  57  are threaded into tapped openings  58  formed in the cylinder head casting  15  on opposite sides of the openings  21  of the intake passages  19 . These tapped openings  58  extend perpendicularly to the cylinder head surface  22 . 
     The intake manifold  13  and its attachment to the cylinder head casting as thus far described may be considered to be conventional. The invention deals primarily with the fuel supply system  14  and its manner of attachment to the cylinder head casting  15  and its relationship to the induction system and specifically the flanges  56  of the manifold runners  55  and their attachment to the cylinder head surface  22 . This structure will be described now. 
     It has been noted that the intake passages  19  are Siamesed. At a point where the passages merge upstream of the valve seats  26 , there is provided a recess  59  in the cylinder head. A fuel injector nozzle portion  61  extend into this recess and sprays along a flow axis Sa directed generally in a downstream direction and toward the intake valve seats  24 . 
     The fuel injector nozzle  61  forms a main portion of a fuel injector assembly  62  that is received within an injector opening  63  that is machined into a surface  64  of the cylinder head casting  15 . This surface  64  is slightly offset from but parallel to the surface  22  to which the manifold flanges  56  are affixed. 
     The fuel injectors  62  are of the electrically operated type and have an actuating solenoid that is provided with a terminal  65  to which a wire harness (not shown) is affixed so as to control the timing of opening and closing of the injector valves thereof 
     A fuel supply system supplies fuel to the fuel receiving nozzles of the injector  62  and this includes a main fuel rail  66 . This main fuel rail  66  has complementary sealed openings that interconnect with the fuel receiving portions of the injector  62  so as to provide a leak-proof fuel supply thereto. 
     Fuel is delivered from a remote fuel tank through a pressure conduit  67  as best seen in FIG.  2 . This pressure conduit  67  extends to the forward or cam drive end of the engine where it is connected to a banjo fitting  68 . The banjo fitting  68  supplies fuel to a central flow passage  69  of the main fuel rail  66 . 
     The opposite end of the main fuel rail  66  mounts a pressure regulator  69  which regulates pressure by dumping excess fuel back to the remote fuel tank through a return line  71 . In order to ensure that the injected fuel is at a pressure that is at a fixed amount above the pressure of the air into which it is injected, the pressure regulator  69  has a portion  72  that receives air at the pressure in the plenum chamber  54  through a conduit  73 . Hence, the pressure of the fuel injected is always maintained at a fixed value above the pressure of the air into which it is injected. 
     A pair of angularly shaped mounting bracket  74  are affixed to one side of the main fuel rail  66  in the area between adjacent injectors and between the manifold runners  55  as best seen in FIG.  2 . These mounting brackets  74  may be formed from a non-metallic material such as a resinous plastic or the like. They are affixed to the main fuel valve  66  by threaded fasteners  75 . The other leg of these brackets  74  engages a circular non-metallic washer  76  that is interposed between this bracket leg and the cylinder head surface  54 . 
     Threaded fasteners  77  are passed into tapped openings  78  formed in the cylinder head casting  15 . The fuel rail  66  is formed with a pair of reliefs  79  adjacent the heads of the fasteners  77  so as to facilitate their access. 
     It should be noted that the cylinder head casting has a portion  81  that extends inwardly toward the head bolt opening  18 . These tapped openings  78  extend into this portion but do not penetrate it. This projection  81  is such that it will not obscure the access to the head of the fastener which affixes the cylinder head casting  15  to the cylinder block and which engages a machined surface  82  formed on the upper side of the cam chamber portion of the cylinder head casting  15 . 
     Because the axes of the tapped openings  78  is parallel to the axis of the tapped opening  58  that receives the manifold fasteners  57 , machining is simplified and can be done with a gang drill. Also, it should be noted that the axes of the fasteners  77 , indicated at  83  in FIG. 3, are parallel to the axes  84  of the manifold runner  55  and the inlet portion of the intake passages  19 . Thus, setup time is facilitated also with this arrangement. 
     Thus, from the foregoing description, it should be readily apparent that the described cylinder head construction permits the attachment of the intake manifold and the fuel rail in close proximity to each other without interference and in such a manner as to simplify machining. Of course, the foregoing description is that of a preferred embodiment of the invention and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.