Abstract:
An internal combustion engine having poppet valves is disclosed, wherein induction ports serving intake valves are siamesed. Induction ports have proximal portions about parallel to the valve stem axis of their associated intake valves, and distal portions roughly parallel to the engine block deck surface. The proximal portions flare to greater width with increasing proximity to valve heads. The distal portions are smaller in cross section than the proximal portions. The combustion chamber includes a bulge projecting away from the piston crown, providing additional space for induction air flow.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The present disclosure relates to internal combustion engines, and more particularly, to a breathing arrangement for improving volumetric efficiency in poppet valve engines. 
       BACKGROUND 
       [0002]    Many different valve and manifolding designs have been proposed for internal combustion engines. One goal that has remained consistent is that of maximizing volumetric efficiency. In naturally aspirated engines, it has been proposed to provide four or even five valves for each cylinder. Manifolds have been proposed to increase induction air flow. Cylinder configurations and valve orientations have been proposed to maximize induction volume. There remains room in the art of internal combustion engines for further improvement in volumetric efficiency. 
       SUMMARY 
       [0003]    The disclosed concepts address the above stated situation by providing a valve port configuration which, taken together with certain valve area ratios of exhaust valves and intake valves, produces improved volumetric efficiency. A single induction ports serves two adjacent intake valves. The ratio of the area of an exhaust valve to the area of an intake valve is approximately 0.65. 
         [0004]    Additionally, the port is configured to eliminate the usual sharp angle of approach of induction air flow at the valve. Whereas many conventional port designs have a nearly right angled turn proximate the intake valve, in the present disclosure, the angle of approach is far more gradual, so that direction of induction air flow approaches parallel to the axis of the valve stem. 
         [0005]    It is an object to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
         [0006]    These and other objects will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Various objects, features, and attendant advantages of the disclosed concepts will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0008]      FIG. 1  is a nested block diagram of components of an engine, according to at least one aspect of the disclosure; 
           [0009]      FIG. 2  is a diagrammatic top plan view of a representative pair of cylinders of the engine of  FIG. 1 , according to at least one aspect of the disclosure; 
           [0010]      FIG. 3  is a diagrammatic side view of the cylinder head of  FIG. 2 , shown partly in cross section, according to at least one aspect of the disclosure; 
           [0011]      FIG. 4  is a side view of the cylinder head of  FIG. 2 , taken along line  4 - 4  in  FIG. 2 , and shown partly in cross section, according to at least one aspect of the disclosure; 
           [0012]      FIG. 5  is a diagrammatic top view of a representative pair of cylinders of the engine of  FIG. 1 , according to at least on additional aspect of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring first to  FIG. 1 , according to at least one aspect of the disclosure, there is shown a reciprocating piston internal combustion engine  100 , comprising an engine block  102  supporting at least one cylinder  104  enclosing a piston  106  slidably and reciprocably disposed within cylinder  104 . Engine block  102  has at least one deck  108 . Reciprocating piston internal combustion engine  100  also includes an output shaft  110  supported by engine block  102 , a power linkage  112  which operably conducts power developed by reciprocation of piston  106  within its associated cylinder  104  to output shaft  110 . Reciprocating piston internal combustion engine  100  further includes a cylinder head  114  defining therein a combustion chamber  116  for each cylinder  104 , an induction path  118  disposed to conduct fresh combustion air to each cylinder  104 , and an exhaust path  120  disposed to conduct spent combustion products away from each cylinder  104 . Cylinder head  114  closes one end of cylinder  104 . Cylinder  104  abuts engine block  102  at deck  108 . 
         [0014]    For each cylinder  104 , there is an intake valve  122  in induction path  118 , intake valve  122  disposed to open and close induction path  118  to flow of fresh combustion air to each cylinder  104 . Intake valve  122  has an intake valve head  124  and a stem  126  having a stem longitudinal axis  126 . For each cylinder  104 , there is an exhaust valve  130  disposed in exhaust path  120  to open and close combustion chamber  116  to exhaust path  120 . Exhaust valve  130  has an exhaust valve head  132 . 
         [0015]    Induction path  118  includes a siamesed port  134  for pairs of adjacent cylinders  104 , wherein siamesed port  134  has a distal portion  136  having a distal portion cross sectional area  138  and a proximal portion  140  having a proximal portion cross sectional area  142  greater than distal portion cross sectional area  138 . 
         [0016]    A siamesed port is a passage which splits or branches from a single passage to two passages, to serve two adjacent intake valves  122 . 
         [0017]    Some components of reciprocating piston internal combustion engine  100  have been omitted from  FIG. 1 . 
         [0018]    Apart from siamesed port  134  of induction path  118 , components of reciprocating piston internal combustion engine  100  are well known. Deck  108  is a surface ordinarily oriented upwardly when engine block  102  is installed in a motor vehicle (not shown). There may be more than one deck  108 . For example, “V” configured engines such as V4, V6, V8, V10, and V12 engines (none of these is shown) have two decks  108 . Single cylinder engines and in-line two-, three-, and four-cylinder engines (none shown) have one deck  108 . 
         [0019]    Output shaft  110  may be a crankshaft for example. Power linkage  112  may comprise a connecting rod (not shown), a yoke (not shown), or other mechanical component coupling each piston  106  to output shaft  110 . 
         [0020]    Depending upon context, combustion chamber  116  will be understood to refer to an open volume above each associated piston  106 , or to refer to that open volume and a wall of cylinder head  114  bounding the open volume. 
         [0021]    Induction path  118  will be understood to encompass passages within cylinder head  114 , and in a complete engine, passages including those in intake manifold(s) where provided, and ancillary components such as throttle body where provided, air mass flow sensor, and air filter. Exhaust path  120  will be understood to encompass passages within cylinder head  114 , and in a complete engine, passages in exhaust manifold(s) where provided. Complete engines will be understood to include supporting systems such as fuel supply systems, cooling systems, lubrication systems, ignition systems, starting systems, electrical charging systems, engine operation sensors, throttles, superchargers including turbochargers where provided, power brake pumps where provided, air pumps for post cylinder combustion air, power steering pumps, and pulleys, brackets, and other components for other vehicular systems such as air conditioning systems, emission control systems, and other known systems. The supporting systems described above are well known and need not be further detailed herein. 
         [0022]    Referring also to  FIG. 2 , in reciprocating piston internal combustion engine  100 , when considered in plan view, proximal portion  140  increases in width  144  with greater proximity to intake valves  122  associated with siamesed port  134 . Width  144  is greater in magnitude than width  146  of distal portion  136  of siamesed port  134 . 
         [0023]      FIG. 2  shows cylinder head details for a bank of four cylinders. 
         [0024]    Referring additionally to  FIG. 3 , which shows cylinder and cylinder head details for a single cylinder  104 , in reciprocating piston internal combustion engine  100 , proximal portion  140  of siamesed port  134  is inclined relative to deck  108  of engine block  102  such that air flow proximate each intake valve head  124  is generally parallel to stem longitudinal axis  128  of each intake valve  124 . Direction of air flow proximate intake valve head  124  is indicated by an axis  148  approximating the geometric center line of proximal portion  140  of siamesed port  134 . Recognizing that contours of siamesed port  134  vary, “generally parallel” will be understood to deviate from parallel by up to twenty-five degrees from stem longitudinal axis  128 . This angle is indicated by an arrow  150 . 
         [0025]      FIG. 3  also shows that in reciprocating piston internal combustion engine  100 , distal portion  136  of siamesed port  134  has a central axis  152  generally parallel to deck  108  associated with siamesed port  134 . 
         [0026]    In reciprocating piston internal combustion engine  100 , proximal portion  140  of siamesed port  134  has a central axis  148  at deck  108  intersecting central axis  152  of distal portion  136  of siamesed port  134  at an angle in a range of forty-five to sixty degrees. The angle of central axis  148  is taken where central axis  148  passes from cylinder head  114  through deck  108  of engine block  102 . Central axis  152  is extended to the right in  FIG. 3  to the point of intersection with central axis  148  to generate the angle in the range of forty-five to sixty degrees. This geometry provides a gradual, curved transition from horizontal flow to almost vertical flow in siamesed port  134 . By contrast with this gradual transition, many conventional engines have intake ports making a nearly perpendicular turn at the valve head, which may introduce unwanted fluid eddy currents and other disruptions to orderly air flow. 
         [0027]    In reciprocating piston internal combustion  100 , each intake valve  122  has an intake valve area, each exhaust valve  130  has an exhaust valve area, and a ratio of the exhaust valve area to the intake valve area is in a range from 0.45 to 0.7. The area of the respective valves  122 ,  130  is based on diameters of heads  124 ,  132  of the valves  122 ,  130 . In a currently preferred embodiment, the ration of the exhaust valve area to the intake valve area is about 0.65. 
         [0028]    Referring again to  FIG. 3 , in reciprocating piston internal combustion engine  100 , combustion chamber  116  comprises a bulge  154  in combustion chamber  116 . Bulge  154  projects away from piston  106  and opens towards piston  106 . Bulge  154  has a distal portion  156  located further from piston  106  than any part of head  124  of intake valve  122  is located from piston  106 . Bulge  154  has a wall portion  158  located proximate head  124  of intake valve  122  which has a slope  160  arranged at an acute angle  161  to deck  108  of engine block  102 . Bulge  154  provides more space for flow of induction air than would occur in the absence of bulge  154 . 
         [0029]    In reciprocating piston internal combustion engine  100 , bulge  154  has a rounded domed configuration at that point  162  farthest from piston  106 . That wall  164  of bulge  154  located farthest from intake valve  122  makes a continuous transition towards coincidence with combustion chamber wall  166 . Alternatively stated, wall  164  makes a gradual, curved transition from point  162  to vertical combustion chamber wall  166 . 
         [0030]    It should be noted at this point that orientational terms such as vertical refer to the subject drawing as viewed by an observer. The drawing figures depict their subject matter in orientations of normal use, which could obviously change with changes in engine design, engine mounting, and the like. Therefore, orientational terms must be understood to provide semantic basis for purposes of description only, and do not imply that their subject matter can be used only in one position. 
         [0031]    Referring also to  FIG. 4 , which shows details of a cylinder head and cylinders of a pair of cylinders  104 , in reciprocating piston internal combustion engine  100 , within each cylinder  104 , each one of intake valves  122  has an axis of travel and each one of exhaust valves  130  has an axis of travel parallel to that of one of intake valves  122 . Direction of travel of valves  122 ,  130  is indicated by an arrow  168 . The actual axis of travel is the same in intake valves  122  as stem longitudinal axis  128  (see  FIG. 3 ). Exhaust valves  130  have similar axes. 
         [0032]      FIG. 4  also shows relative widths  144 ,  146  of proximal portion  142  and distal portion  136 . 
         [0033]      FIG. 5  shows a portion of reciprocating piston internal combustion engine  100 , wherein siamesed port  134  includes, for each pair of cylinders  104 , a first distal portion  136 A having a first central axis  152 A and a second distal portion  136 B having a second central axis  152 B intersecting first central axis  152 A when viewed in an azimuth view. The view of  FIG. 5  is an azimuth view because first and second distal portions  136 A and  136 B, and their respective first and second central axes  152 A,  152 B could be curved. If present, this curvature would not be seen in the azimuth view of  FIG. 5 . Hence even if there were a slight offset of first and second distal portions  136 A,  136 B from deck  108  (see  FIG. 3 ) and consequent misalignment of first and second central axes  152 A,  152 B (misalignment is not shown), there would still be apparent intersection of first and second central axis  152 A,  152 B in the azimuth view. This geometry promotes straighter flow of induction air towards each opening associated with each intake valve  122 , with less choking effect and consequently, greater mass of air entering each cylinder  104  during each intake stroke. 
         [0034]    Other than the above described geometry of first and second distal portions  136 A,  136 B, geometric features described herein afford greater cross sectional area for induction breathing than occurs in other engine designs. Large intake valve area is provided to exploit the greater induction breathing cross sectional area. 
         [0035]    In the above description, numerous specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known components or methods have not been described in detail but rather in a block diagram in order to avoid unnecessarily obscuring the present invention. Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present invention. 
         [0036]    While the disclosed concepts have been described in connection with what is considered the most practical and preferred implementation, it is to be understood that the disclosed concepts are not to be limited to the disclosed arrangements, but are intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible. 
         [0037]    It should be understood that the various examples of the apparatus(es) disclosed herein may include any of the components, features, and functionalities of any of the other examples of the apparatus(es) disclosed herein in any feasible combination, and all of such possibilities are intended to be within the spirit and scope of the present disclosure. Many modifications of examples set forth herein will come to mind to one skilled in the art to which the present disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. 
         [0038]    Therefore, it is to be understood that the present disclosure is not to be limited to the specific examples presented and that modifications and other examples are intended to be included within the scope of the appended claims. Moreover, although the foregoing description and the associated drawings describe examples of the present disclosure in the context of certain illustrative combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative implementations without departing from the scope of the appended claims.