Patent Publication Number: US-6216659-B1

Title: Engine cylinder head

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an internal combustion engine and more particularly to an improved cylinder head construction for such engines. 
     As is well known, internal combustion engines whether they are four or two cycle type generally are comprised of three major external engine bodies. These include the cylinder head body, the cylinder block body, and the crankcase body. Sometimes these bodies are combined and other times parts of each body may be formed from a part of the adjacent body. For the most part, however, each body is a separate element and is detachably or otherwise connected to the remaining bodies. 
     This presents significant problems with connection with the cylinder head design, particularly where the engine is of the four cycle type and has overhead valves and a valve actuating mechanism that is mounted in the cylinder head for operating these valves. It is quite difficult to provide a single piece assembly that will serve all of the purposes and which can be made in mass production quantities at a relatively low cost and still have high accuracy. 
     For example, motorcycle engines may at times utilize overhead valves that are operated by one or more cam shafts positioned in the crankcase or at a lower portion of the engine and operated via push rods and rocker arms. With such an arrangement, the cylinder head must form the combustion chamber surface, the intake and exhaust passages and valve seats for gas exchange with the combustion chamber, the mounting for the valves for controlling the flow through these passages and the actuating mechanisms for operating these valves. Furthermore, the actuating mechanism is frequently contained within a cover so as to protect the mechanism and particularly permit its lubrication without encroachment of foreign material into the mechanism while permitting ease of access for servicing. 
     Thus, many times the engine cylinder head is comprised of a main cylinder head member and a cam or valve cover that covers the outer periphery of the cylinder head member. However, this still gives rise to certain problems in connection with mounting all of the various components and arranging them in the cylinder head. 
     It is, therefore, a principal object of this invention to provide an improved cylinder head assembly for an overhead valve engine wherein the cylinder head is made up of a few major parts that are detachably connected to each other so as to facilitate production, maintain close tolerances and still keep the cost low. 
     It is a further object of this invention to provide an improved and simplified multi-piece cylinder head assembly for an overhead valve engine. 
     As has been noted, serviceability as well as assembly are important in the design. This is particularly true with respect to the cylinder head assembly. Its components are among those which require periodic adjustment or other servicing. 
     It is, therefore, a still further object of this invention to provide an improved and simplified cylinder head assembly of multi-piece construction to facilitate assembly as well as servicing. 
     SUMMARY OF THE INVENTION 
     This invention is adapted to be embodied in a cylinder head assembly for an internal combustion engine. The cylinder head assembly is comprised of at least four major components. These components include a main cylinder head member which forms the combustion chamber with the piston and associated cylinder bore as well as the flow passages for induction into the combustion chamber and exhaust from the combustion chamber. In addition, a rocker arm carrier is adapted to be detachably connected to the main cylinder head member and supports at least some components for the valve actuating mechanism for operating valves that control the flow through the flow passages of the main cylinder head member. A cylinder head cover assists in detachably connecting the rocker arm carrier to the main cylinder head member and provides a peripheral area around the valve operating mechanism. Finally, a valve cover is affixed to the other members and encloses the valve operating mechanism as well as facilitating its servicing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a motorcycle constructed in accordance with an embodiment of the invention. 
     FIG. 2 is a side elevational view of the engine looking in the opposite direction from FIG.  1  and with the push rod covers either partially or completely removed and other portions broken away to show portions of the valve operating mechanism. 
     FIG. 3 is a cross-sectional view taken generally along the line  3 — 3  of FIG.  2 . 
     FIG. 4 is an enlarged cross sectional view through one of the cylinder head members of the cylinder head assembly taken along the same plane as FIG.  3 . 
     FIG. 5 is an enlarged cross sectional view through the one of the cylinder head members shown in FIG. 4 taken along a plane perpendicular to that plane. 
     FIG. 6 is an enlarged view looking in the same general direction as FIG. 2, but showing the valve operating mechanism in solid lines with the remainder of the engine being shown in phantom. 
     FIG. 7 is a view looking in the same direction as FIG. 6 but showing the timing driving for the camshafts. 
     FIG. 8 is an enlarged cross sectional view taken along the line  8 — 8  in FIG. 7 showing further details of the cam shaft drive. 
     FIG. 9 is an enlarged cross-sectional view taken along a line  9 — 9  of FIG.  6  and shows the tappet supporting mechanism. 
     FIG. 10 is an exploded view showing one of the cylinder head assemblies. 
     FIG. 11 is an enlarged top plan view of the main cylinder head member. 
     FIG. 12 is a view looking in the same direction as FIG.  11  and shows the main cylinder head member as attached to the associated cylinder block. 
     FIG. 13 is a top plan view showing the rocker arm carrier member of the cylinder head assembly before attachment. 
     FIG. 14 is a top plan view showing in solid lines the rocker arm mechanism associated with the rocker arm carrier member with the rocker arm carrier member being shown in phantom. 
     FIG. 15 is a top plan view showing the rocker arm carrier member, rocker arms and main cylinder head member assembled. 
     FIG. 16 is a top plan view showing the cylinder head cover affixed to the assembly shown in FIG.  15 . 
     FIG. 17 is a bottom plan view of the valve cover member. 
     FIG. 18 is a top plan view showing the completed cylinder head assembly with the cam cover in place. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
     Referring first primarily to FIG. 1, a motorcycle is illustrated in side elevational view and is identified generally by the reference numeral  21 . The motorcycle  21  is powered by an internal combustion engine, indicated generally by the reference numeral  22  and which is constructed in accordance with an embodiment of the invention. The motorcycle  21  is shown as a typical environment in which the invention may be utilized. 
     The invention has particular utility in conjunction with motorcycle applications because the engine  22  is substantially exposed, is air cooled and also must be compact in construction and provide a high specific output. Although this specific environment is shown as a typical environment with which the invention may be utilized, it will be readily apparent to those skilled in the art how the features of the engine  22  can be utilized with a number of other applications. 
     The motorcycle  21  is comprised of a frame assembly  23  upon which the engine  22  is suspended in a known manner. This frame assembly  23  dirigibly supports a front fork  24  on which a wheel  25  is rotatably journaled. A fender  26  covers this front wheel  25 . The steering of the vehicle is controlled by a handlebar assembly  27  that is fixed to the upper end of the front fork  24  in a manner well known in this art. 
     A rider&#39;s seat  28  is carried by the frame assembly  23  rearwardly of the engine  22  and above it. A fuel tank  29  for the engine is mounted on the frame  23  forwardly of the seat  28 . 
     Finally, a rear wheel  31  is journaled by the frame assembly  23  in a suitable manner and is driven by a transmission contained within a crankcase transmission assembly  32  of the engine  22  through a final drive which may comprise a driving belt covered by a cover  33  for driving a pulley  34  or sprocket fixed for rotation with the rear wheel  31 . 
     The construction of the engine  22  will now be described in more detail referring first primarily to FIGS. 2 and 3. In the illustrated embodiment, the engine  22  is of the V twin type and operates on a four cycle principle. To this end, the engine  22  is comprised of an engine body assembly including a cylinder block portion, indicated generally by the reference numeral  35 , which is formed with a pair of angularly related cylinder banks  36  and  37  that are disposed at a V angle to each other. These cylinder banks  36  and  37  are formed by cylinder barrels that are affixed to an upper portion of a crankcase member  38  which with the cylinder banks  36  and  37  completes the cylinder block portion  35 . 
     The crankcase member  38  defines a crankcase portion of the engine body that includes the combined crankcase transmission assembly  32  and rotatably journals a crankshaft  39  in any suitable manner. 
     Each cylinder bank  36  and  37  is formed with a respective cylinder bore  41  in which a piston  42  reciprocates. The pistons  42  are connected to the upper or small ends of connecting rods  43  in a known manner. The connecting rods  43  are journaled in side-by-side relationship on a throw of the crankshaft  39  as best seen in FIG.  3 . 
     A cylinder head assembly, indicated generally by the reference numeral  44  is affixed to each cylinder bank  36  and  37  by means that include threaded fasteners  45 . In accordance with the invention, the cylinder head assemblies  44  are each made up of four major components. These comprise a main cylinder head member  46 , a rocker arm carrier  47 , a cylinder head cover  48  and a valve cover  49 . These main components are shown in FIG.  10  and will be described in more detail later by reference to this and other figures, specifically FIGS. 11-17. 
     Still continuing to refer primarily to FIGS. 2 and 3, the transmission assembly for driving the rear wheel  31  from the crankshaft  39  will now be described. As has been previously noted, this transmission assembly is contained in part in the combined crankshaft transmission assembly  32 . 
     Affixed to one end of the crankshaft  39  is a main drive gear  51  which is enmeshed with a driven gear  52  of a change speed transmission, indicated generally by the reference numeral  53 . The driven gear  52  is coupled via a selectively actuatable multiple disc clutch  54  to a primary shaft  55  of the change speed transmission  53 . 
     This primary shaft  55  carries a plurality of primary gears which are enmeshed with secondary gears that are carried on a secondary shaft  56  of the transmission  53 . By selectively coupling the gears on the primary and secondary shafts  55  and  56  to the shafts through a suitable shifting mechanism, it is possible to change the drive ratio between the crankshaft  39  and the secondary shaft  56 . The secondary shaft  56  thus, functions as the output shaft of the change speed transmission  53 . 
     An understanding of the details of the transmission  53  is not believed to be necessary to permit those skilled in the art to practice the invention. It should be readily apparent that the invention may be utilized in conjunction with any desired type of transmission. 
     The secondary transmission shaft  56  or output shaft carries a sprocket or toothed wheel  57  which is engaged with a drive belt  58 . This drive belt  58  is contained within a transmission case enclosed by a cover assembly  59 . 
     The drive belt  58  drives a further sprocket  61  that is coupled to a transmission output shaft  62 . A further drive sprocket or pulley  63  is affixed to the opposite end of this output shaft  62 . This belt drives the rear wheel sprocket  34  as previously noted. 
     The general construction of the cylinder head assembly  44  will now be described by primary reference to FIGS. 3-5 and  10 . A more detailed description of each cylinder head assembly  44  and its manner of attachment to the respective cylinder bank  36  or  37  will follow later in connection with the detailed description of FIGS. 10-17. 
     As has been previously noted, the cylinder head assembly  44  is made up of four major components, the main cylinder head member  46 , the rocker arm carrier  47 , the cylinder head cover  48 , and the valve cover  49 . These components are preferably formed from light alloy materials, such as cast aluminum or aluminum alloys. 
     The main cylinder head member  46  is formed with a recess  64  in its lower surface which overlies the cylinder bore  41  of the respective cylinder bank and forms the combustion chamber of each cylinder bank  36  and  37  with the head of the piston  42  and with the cylinder bore  41 . In the illustrated embodiment, the cylinder head recess  64  is formed with four ports, two of which lie on the side of the engine toward the valley between the cylinder banks  36  and  37  and which comprise intake ports indicated by the reference numerals  65 . 
     These ports are served and supplied with a fuel air charge by an induction system. This induction system includes carburetors or other charge formers  66  that are conveniently disposed between these cylinder banks  36  and  37  and which are associated with the intake passages  67  of the respective cylinder head assemblies  44 . These charge formers will be described in more detail later. These passages terminate in an outer surface of each cylinder head member  46  and receive the respective carburetors  66 . 
     Poppet-type intake valves  68  are slidably supported in each cylinder head member  46  by means that include valve guides  69 . These valves  68  are urged toward their closed position in closing relationship to the intake ports  65  by coil compression spring assemblies  71 . These spring assemblies  71  act against keeper retainer assembly  72  for holding the valve  68  in their closed position. The mechanism for opening the valves  68  will be described later. 
     On the side of the cylinder head recesses  64  opposite the intake ports  65 , there are provided exhaust ports  73 . These exhaust ports  73  are valved by poppet-type exhaust valves  74  which are also reciprocally mounted in the cylinder head members  46  by means of valve guides  75 . Coil compression spring assemblies  76  act against keeper retainer assembly  77  for holding the exhaust valves  74  in their closed position. These exhaust valves  74  are opened in a manner which will also be described shortly. 
     The exhaust ports  73  in the cylinder head members  46  form the inlets to exhaust passages  78  formed in the cylinder head members  46  and which are adapted to detachably received an exhaust system shown in phantom and indicated by the reference numeral  79  for discharging the exhaust gasses from the combustion chambers to the atmosphere. Since the exhaust system  79  constitutes no part of the invention, it has not been illustrated in detail and will not be described further. Those skilled in the art will readily understand how the invention can be utilized with a wide variety of types of exhaust systems. 
     The four valve per cylinder, cylinder head assembly  44  as thus far described is further complimented by a means of a dual ignition system. To this end, the cylinder head members  46  are each formed with a pair of tapped openings that receive spark plugs  81  as best seen in FIG.  4 . These spark plugs  81  are fired by a suitable ignition system and will ensure rapid flame propagation and complete combustion of the fuel air charge that has been delivered to the combustion chambers from the carburetors  66 . 
     At this point, it might be well to state that although the invention is described in conjunction with a carbureted engine, the principles of the invention can be equally as well utilized with engines having other types of charge formers, such as fuel injection systems. 
     The valve operating mechanism for operating the intake valve  68  and exhaust valves  74  for each cylinder bank will now be described by particular reference to FIGS. 2,  3 , and  6  through  8 , although portions of this valve operating mechanism also appears in other figures. 
     First, it should be noted that the crankcase member  38  is formed with an internal wall that has a central opening  82  through which one and of the crankshaft  39  extends. A timing gear  83  is affixed for rotation with this end of the crankshaft  39  by means that include a fastener assembly  84  and key arrangement so that the timing gear  83  will be driven at crankshaft speed. The wall of the crankcase member through which the crankshaft extends is formed with a cylindrical projection indicated in the drawings by the reference numeral  85  for reference purposes. 
     As best seen in FIGS. 7 and 8, the timing gear  83  is encircled by the projection  85  and is in this area enmeshed with a driven camshaft timing gear assembly, indicated generally by the reference numeral  86 . This timing gear assembly  86  is of the split gear type so as to take up backlash in the system. This assembly is held onto a cam driving shaft  87  by means of a threaded fastener  88 . There is a two to one speed reduction in this transmission, as is well known in the art. 
     This shaft  87  penetrates through a cover  90  that forms a gear case with the wall projection  85  and there drives a first camshaft driving gear  91  which has a driving relationship with a first camshaft  92  which is associated with one of the cylinder banks  36  and  37 . In the illustrated figures, this is the cylinder bank  36 . 
     The driving gear  91  is also a split-type backlash take up type of gear and is drivingly coupled to a second camshaft driving gear  93  which is associated with a camshaft  94  for the remaining cylinder bank, i.e., the cylinder bank  36 . Because of this relationship between the driving gears  91  and  93 , these gears will rotate in opposite directions. 
     The area above the crankcase member projection  85  adjacent each camshaft  92  and  94  and on the upper side thereof is formed with an opening that receives a tappet body  95 . Each tappet body  95  is formed with a pair of bores that receive, respectively, an intake tappet  96  and an exhaust tappet  97  for the respective cylinder banks. These tappets  96  and  97  are engaged by the intake and exhaust cam lobes  98  and  99 , respectively, of each camshafts  92  and  94 . Since the construction of each camshaft is basically the same, except for the fact that they rotate in opposite directions, the same reference numerals are applied to the cam lobes  98  and  99  and the tappet bodies  96  and  97  for each cylinder bank. 
     As has been noted, the engine  22  is air cooled and to this end, both the cylinder barrels  36  and  37  are formed with cooling fins  101 . These cooling fins  101  extend generally around the periphery of the engine body, but are partially interrupted on the sides adjacent the camshaft  92  and  94  so as to provide recesses through which push rods  102  and  103  for each cylinder bank extend. The push rods  102  are associated with the intake tappets  96 , while the push rods  103  are associated with the exhaust tappets  97 . These push rods  102  and  103  extend upwardly and in effect cross over each other slightly as seen in FIGS. 2 and 6. These push rods  102  and  103  are encircled by a protective tube in a manner which will be described shortly. 
     Referring now primarily to FIGS. 2,  6 ,  14  and  15  the intake and exhaust valve push rods  102  and  103 , respectively, extend upwardly along the side of the respective cylinder barrels  36  and  37  to the cylinder head assemblies  44 . The upper end of each of these push rods  102  and  103  cooperate with respective rocker arms  104  and  105  that are supported for pivotal movement on rocker arm shafts  106  and  107 . 
     These rocker arm shafts  106  and  107  are journaled in bosses  108  and  109 , respectively, formed in the cylinder head rocker arm support member  47 . As may be best seen in FIGS. 14 and 15, the rocker arms  102  and  103  pass through a central opening  111  formed in a downwardly extending guide portion  112  of the rocker arm carrier  47 . 
     The rocker arms  104  and  105  have follower portions  113  and  114  that define spherical sockets into which the ends of the push rods  102  and  103  extend. These extensions  113  and  114  are formed at one side of the rocker arm assemblies  104  and  105 . At the other ends thereof, the rocker arm assembly  104  has a pair of extending arms  115  and  116  that are engaged with the tips of the intake valves  68  for their actuation. An adjusting screw  117  is provided on only one of these rocker arm extensions, this being the extension  115 , so as to permit adjustment of the lash in the intake valve train. 
     In a similar manner, the rocker arm  105  has a pair of valve actuating portions  118  and  119  that cooperate with the tips of the stems of the exhaust valves  74  for their actuation. Again, only the rocker arm portion  118  carries an adjusting screw  121  for adjusting the lash in the exhaust valves. 
     As may be best seen in FIGS. 11 and 12, the cylinder head member  46  has openings  120  to receive the fasteners  45  that affix the cylinder head member  46  to the cylinder blocks  36  and  37  and this assembly to the crankcase member  38 . The rocker arm carrier  47  is suitably affixed to the cylinder head member  46 . The head cover  48  is then fixed to the upper side of the rocker arm carrier  47  and the valve actuating mechanism is then closed by the valve covers  49 . This construction will be described in more detail later by reference to FIGS. 10-17. 
     As best seen in FIG. 2, the cylinder blocks  36  and  37  have recesses  122  formed in one side thereof The push rods  102  and  103  extend through these recesses and are encircled by push rod tubes  123 . As seen in FIG. 9, the lower ends of these push rod tubes  123  are sealingly engaged with the tappet carrier member  95  that is fixed to the crankcase member  38  and thus provide a good seal and protection in this area. These tappet carrier members  95  are formed with lubricant return and crankcase ventilation openings  124  to permit lubricant supplied to lubricate the valve operating mechanism in the cylinder head assemblies  44  in a suitable manner to drain back to the crankcase  32 . Also these openings  124  facilitate crankcase ventilation including that within the valve covers  49 . 
     In a like manner, the upper ends of these push rod tubes  123  are sealingly engaged within the projections  112  of the rocker arm carrier  47  and thus, the push rods  102  and  103  are well protected, but there is a neat overall appearance to the engine. Also, the push rods  102  and  103  can be easily removed for servicing, as should be readily apparent. 
     As should be apparent from the foregoing description, the invention deals primarily with the construction of the cylinder head assembly  44  and its manner of attachment to the respective cylinder blocks  36  and  37 . This construction will now be described in detail by reference to FIGS. 10-17. 
     Referring first to the attachment of the main cylinder head member  46  to the respective cylinder blocks  36  or  37  and to FIGS. 10-12, it has been noted that the cylinder head member  46  has openings  120  that pass the threaded fasteners  45  for affixing this member  46  to the cylinder block  36  or  37 . In addition, locating pins  125  may be provided that are engaged in pilot openings in the cylinder blocks  36  and  37  and the cylinder head member  46  to ensure accurate location of the assembled parts. 
     It has also been noted that the spark plugs  81  are mounted in the cylinder head member  46 . On each side of the cylinder head member  46 , there are provided recesses  126  which provide clearance to tapped openings  127  into which these spark plugs  81  are threadedly engaged. 
     Of course, a cylinder head gasket  128  is interposed between the cylinder head member  46  and the respective cylinder block  36  and  37  for sealing purposes. 
     The upper end of the cylinder head member  46  is provided with a plurality of tapped openings  129  that are aligned with openings  131  formed in the rocker arm carrier member  47 . When the rocker arm carrier  47  is assembled onto the main cylinder head member  46  a gasket  132  is interposed therebetween. Threaded fasteners  133  are then passed through these openings  131  and threaded into the tapped openings  129  of the cylinder head member  46  so as to fix the rocker arm carrier  47  thereto. 
     Once the rocker arm carrier  47  is affixed to the cylinder head member  46  (FIG.  15 ), the rocker arm shaft  106  and  107  can be inserted into the bosses  108  and  109 , respectively. The end bosses  108  and  109  adjacent the push rods  102  and  103  are formed with tapped openings  134  to receive locking fasteners  135  so as to hold the rocker arm shafts  106  and  107  in the bosses  108  and  109 . 
     Having thus positioned the rocker arm carrier  47  into assembly with the cylinder head member  46 , then the cylinder head cover  48  is placed on this assembly. A sealing gasket  135  is positioned between the cylinder head cover  48  a peripheral flange  137  of the rocker arm carrier  47 . Then threaded fasteners  138  are fixed in placed. These threaded fasteners  138  pass through respective openings  139  formed in the rocker arm carrier  48  and are threaded into tapped holes  141  formed in the cylinder head member  46 . The assembly thus now is as appears in FIG.  16 . 
     Referring now primarily to FIGS. 13 and 15, it be seen that the rocker arm carrier  47  is provided with a pair of windows  142  which overlie the valve guides  68  and  75  at each side of the cylinder head assembly  44  so as to permit the valve stems and springs to extend upwardly through this rocker arm carrier member  47 . In addition, the rocker arm carrier member  47  is provided with an additional window  143  which overlies one of the spark plug wells  127  so that the spark plug  81  can pass therethrough. The remaining spark plug well  127  is open through the recess  126  which overlies the corresponding recess of the same number formed in the cylinder head member  46 . 
     Once the cylinder head assembly is completed in the configuration as shown in FIG. 16, it is ready to receive the valve cover  49 . The cylinder head cover member  48  has an upper surface that receives a sealing gasket  144 . The valve cover  49  has a lower surface  145  that engages this gasket  144  this surface  145  being shown in FIG.  17 . 
     A plurality of openings  146  are formed in this surface  145  and overlie tapped openings  147  formed in the cylinder head cover member  48  so as to receive threaded fasteners  149  for fixing the valve cover  49  to the cylinder head cover  48  and accordingly the subassembly previously described. Alignment with the cylinder head cover  48  is also facilitated by locating pins (not shown) received in bored holes  151  and  152  formed in the facing surfaces of the valve cover  49  and cylinder head cover  48 , respectively. 
     In addition to the fasteners  149  that fix the valve cover  49  to the cylinder head cover  48  directly there are further fasteners  153  that provide a connection directly to the rocker arm carrier  47 . These fasteners  153  pass through holes  154  formed in the valve cover  49  and openings  155  formed in the cylinder head cover  48 . They are received in tapped holes  156  formed in the rocker arm carrier  48 . Thus these fasteners  153  function to sandwich the head cover  48  between the valve cover  49  and the rocker arm carrier  47 . 
     The valve cover surface  145  is also formed with reliefs  157  to clear the head cover fasteners  138 . 
     Finally access to the spark plugs  81  is facilitated by an opening  158  that is aligned with the rocker arm carrier opening  143  and one of the cylinder head recesses  126 . A recess  159  of the valve cover  49  is aligned with the other cylinder head recess  126  and the like numbered recess of the head cover  48 . Encircling this recess  159  are lugs that receive fasteners for mounting an accessory such as a wire loom or the like (not shown). 
     Thus, from the foregoing description, it should be readily apparent that the engine construction is quite compact and provides a very effective way cylinder head assembly that facilitates assembly and servicing. Of course, the foregoing description is that of the 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.