Abstract:
An engine is provided with an open deck cylinder block having an open water jacket that surrounds a plurality of cylinders that are joined together in a Siamese design by a cylinder bore bridge. The engine also includes a cylinder head gasket, and a cylinder head. For the purpose of removing excess heat from the cylinder bore bridge, cooling channels are provided that allow coolant to flow from the engine block water jacket, across the cylinder bore bridge, and into a cylinder head coolant passageway. In addition, coolant is prevented from flowing from the water jacket on one side of the cylinders, across the bore bridge, and into the water jacket on the other side of the cylinders.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to cooling an internal combustion engine having a cylinder block with Siamese cylinders. 
       BACKGROUND 
       [0002]    Internal combustion engines include cooling systems for removing excess heat that is produced from the combustion of fuel and friction of moving components. Removal of the excess heat is necessary to prevent the mechanical failure of engine components. The cooling systems typically include a liquid coolant that is pumped through passageways (sometimes known as water jackets) in the engine block, cylinder head, and other engine components. Heat is transferred to the liquid coolant from the engine components when the coolant flows through the various passageways in the engine components. Heat is then transferred from the liquid coolant to the surrounding environment through a heat exchanger, such as radiator. Once the heat is transferred to the surrounding environment, the liquid coolant is redirected through the passageways in the engine components and the process is repeated. 
         [0003]    An internal combustion engine having cylinders that share a common wall is known as a “Siamese design” and the common wall is known as the “bore bridge.” The bore bridge will experience high temperatures because it is in close proximity to the two combustion chambers of the adjacent cylinders, and to the two sets of piston rings that transfer heat to the cylinder block. Packaging of a cooling system in the area of the bore bridge is also difficult adding to the increased temperature of the region. 
         [0004]    Various efforts have been made to cool the bore bridge. It is known to drill cooling channels within the bore bridge that extend between the water jacket in the engine block and the cylinder head. This configuration presents limitations in the flow of the liquid coolant through channels in the bore bridge because of a limited pressure differential and channel cross sectional area. 
         [0005]    It would be desirable to provide a cooling channel in the bore bridge that has an adequate pressure differential and flow area to allow liquid coolant to sufficiently flow through the channel. 
       SUMMARY 
       [0006]    In at least one embodiment, an engine is provided having an open deck cylinder block that has a deck with an open water jacket that surrounds a number cylinders, and has a Siamese design where the cylinders share a common wall known as the bore bridge. The bore bridge includes a cooling channel that is open to the deck and extends across the bore bridge from the water jacket on one side of the cylinder to an end point short of the water jacket on the other side. A cylinder head gasket has a bottom surface that is disposed of on the deck of the cylinder block, and a cylinder head has a face surface that is disposed of on a top surface of the cylinder head gasket. The cooling channel cooperates with water jacket to enable coolant to flow from the water jacket to an inlet port in the cylinder head, the inlet port being located proximate to the end point of cooling channel. 
         [0007]    In at least one additional embodiment, an open deck cylinder block is provided. The open deck cylinder block has an open water jacket that surrounds the cylinders and has a Siamese design where the cylinders share a common wall known as the bore bridge. The bore bridge includes a cooling channel that is open to the deck and extends across the bore bridge from the water jacket on one side of the cylinder to an end point short of the water jacket on the other side. 
         [0008]    In at least one additional embodiment, a cylinder head gasket for use in an engine having an engine block with an open deck Siamese cylinder design is provided. The generally planar gasket body has an upper surface that cooperates with cylinder head and a lower surface that cooperates with a deck surface of an engine block. The cylinder head gasket has an inlet port in the lower surface that is open to the water jacket in the cylinder block and is adjacent to one side of a cylinder bore bridge that is formed between two Siamesed cylinders. An outlet port is formed in the upper surface of the cylinder head gasket and is adjacent to an opposite side of the cylinder bore bridge and open to a cylinder head coolant passageway. The outlet port is also sealed from the water jacket on the opposite side of the cylinder bore bridge. A first elongate cooling channel in the cylinder head gasket extends between the inlet and outlet ports for overlying and open to a second elongate cooling channel in the cylinder bore bridge, which enables coolant to flow from the water jacket on one side of the cylinder bore bridge, across the cylinder bore bridge, to the cylinder head coolant passageway on the opposite side of a cylinder bridge. The first elongate channel flares out at the outlet port to maintain a minimum summed cross sectional flow area of the first and second channels as a cross sectional flow area of the second elongate channel decreases. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1   a  is an exploded isometric view of the engine; 
           [0010]      FIG. 1   b  is an alternative embodiment of the cylinder head gasket; 
           [0011]      FIG. 2  is a transverse cross-sectional view taken along the line  2 - 2  of  FIG. 1   a;    
           [0012]      FIG. 3  is a similar to  FIG. 2 , but shows alternative embodiments of the cylinder head and cylinder head gasket, the cylinder head gasket is not to scale and is shown with an increased thickness for ease of illustration; 
           [0013]      FIG. 4  is a plan view of the head gasket in  FIG. 3 ; 
           [0014]      FIG. 5  illustrates a graph having a plot of the summed cross sectional flow areas of cooling channels in the cylinder block and head gasket versus a distance X; and 
           [0015]      FIG. 6  is partial longitudinal cross-sectional view taken along ling  5 - 5  of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0017]    An exploded view of an internal combustion engine  10  according the present disclosure is illustrated in  FIG. 1   a.  The engine  10  includes an open deck cylinder block  12 , a cylinder head gasket  14 , and a cylinder head  16 . The cylinder head gasket  14  has a lower surface  18  that is disposed of on the deck surface  20  of the cylinder block  12 , and the cylinder head  16  has a face surface  22  that is disposed of on the upper surface  24  of the cylinder head gasket  14 . 
         [0018]      FIGS. 1   a  and  2  show the cylinder block  12  having four cylinders  26  with a Siamese design, where the adjacent cylinders  26  share a common wall known as the bore bridge  28 . The deck surface  20  of the cylinder block  12  is open to a water jacket  30  that surrounds the cylinders  26 . Cooling channels  32  located on the cylinder bore bridges  28  extend a length L from the water jacket  30  on one side of the bore bridge  28  to end points  34  short of the water jacket  30  on the other side of the bore bridge  28 . 
         [0019]    Still referring to  FIGS. 1   a  and  2 , the cylinder head gasket  14  has openings  36  that allow coolant to flow from the water jacket  30  in the cylinder block  12  into a cooling passageway  38  located in the cylinder head  16 . Additional openings  40  in the cylinder head gasket  14  allow coolant to flow from the water jacket  30  in the cylinder block  12  into the cooling channels  32  located on the cylinder bore bridges  28 , from the cooling channels  32  into inlet ports  42  in the cylinder head  16 , which are located proximate to the to end points  34  short of the water jacket  30  on the other side of the bore bridge  28 , and from the inlet ports  42  into the cooling passageway  38  in the cylinder head  16 . The cylinder head gasket  14  also creates a seal preventing coolant from flowing from the water jacket  30  on one side the cylinder bore bridge  28 , across the cooling channels  32 , and into the water jacket  30  on the other side of the cylinder bore bridge  28 . 
         [0020]    Referring to  FIG. 1   b,  an alternative embodiment to the cylinder head gasket  44  is illustrated. The cylinder head gasket  44  includes openings  46  that connect the water jacket  30  in the cylinder block  12  on one side of the bore bridge  28  to the cooling passageway  38  in cylinder head  16  on the same side of the bore bridge. The openings  46  also connect the water jacket  30  in the cylinder block  12  on one side of the bore bridge  28  to the inlet ports  42  in the cylinder head  16  proximate the end points  34  short of the water jacket  30  on the other side of the bore bridge  28 . This embodiment of the cylinder head gasket  44  also creates a seal preventing coolant from flowing from the water jacket  30  in the cylinder block  12  on one side the cylinder bore bridge  28 , across the cooling channel  32 , and into the water jacket  30  in the cylinder block  12  on the other side of the cylinder bore bridge  28 . Additional openings  48  allow coolant to flow directly from the water jacket  30  in cylinder block  12  into the cooling passageway  38  in the cylinder head  16  on the side of the cylinder bore bridge  28  opposite of the cooling channel  32 . 
         [0021]    Referring to  FIGS. 3 and 4 , an additional alternative embodiment of the cylinder head gasket  114  and an alternative embodiment of the cylinder head  116  are provided. The cylinder head gasket  114  has a lower surface  118  that is disposed of on the deck surface  20  of the cylinder block  12 , and the cylinder head  116  has a face surface  122  that is disposed of on an upper surface  124  of the cylinder head gasket  114 . 
         [0022]    The cylinder head gasket  114  includes cooling channels  126 . The cooling channels include inlet ports  128  that cooperate with the water jacket  30  of the cylinder block  12  allowing coolant to flow from the water jacket  30  into the cooling channels, and outlet ports  130  that cooperate with the cooling passageway  138  in the cylinder head  116 , allowing coolant to flow from the cooling channels  126  into the cooling passageway  138 . Between the water jacket  30  of the cylinder block  12  and the cooling passageway  138  in the cylinder head  116 , the cooling channels  126  are open to and adjacent to the cooling channels  32  located on the cylinder bore bridge  28 . At the outlet port  130 , the cooling channel  126  includes a step  132  that creates a seal between the cooling channel  126  and the water jacket  30  on the other side of the bore bridge  28 . 
         [0023]    Referring to  FIGS. 3 ,  4 , and  5 , the cooling channels  126  in the cylinder head gasket  114  and the adjacent cooling channel  32  located on the cylinder bore bridge  28 , have a summed cross sectional flow area. This summed cross sectional flow area is demonstrated by the graph in  FIG. 5 . The summed cross sectional flow area is maintained nearly constant in the proximity of a center point C of the cooling channel  126 . Also, the summed cross sectional flow area will have a value equal to at least the value of the summed cross sectional area at the center point C, as you move in the direction X from the inlet port  128  of the cooling channel  126  to the outlet port  130 . Setting the minimum value of the summed cross sectional flow area at the center point C will ensure that the flow of coolant is not restricted. 
         [0024]    Referring to  FIGS. 4 and 5 , the portion of the cooling channel  126  of the cylinder head gasket  114  near the inlet port  128  has a large cross sectional flow area because the cooling channel  126  near the inlet port  128  is not running adjacent to the cooling channel  32  located on the cylinder bore bridge  28 . As you move in the direction X, away from the inlet port  128  and toward the center point C, the portion of the summed cross sectional flow area represent by the cooling channel  126  (marked A) decreases as the portion summed cross sectional flow area represented by the cooling channel  32  (marked B) increases. As you move in the direction X, away from the center point C toward the outlet port  130 , the cross sectional flow area B of the cooling channel  32  will begin to decrease at a point D beyond the center point C. When the cross sectional flow area B of the cooling channel  32  begins to decrease at point D, the cooling channel  126  begins to open up at the outlet port  130  and the cross sectional flow area A of the cooling channel  126  will begin to increase to ensure the summed cross sectional flow area remains at or above the value of the summed cross sectional flow area at the center point C. 
         [0025]    Referring to  FIG. 6 , a partial cross section of the cylinder block  12  shows a set of adjacent Siamesed cylinders  26  with pistons  134 . The cooling channels  32  of the bore bridge  28  are shown having a depth Y and a width Z. 
         [0026]    Although the preferred embodiments described above were directed to open deck cylinder blocks, the invention should not be construed as limited to open deck cylinder blocks and should include both open and closed deck cylinder blocks. 
         [0027]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.