Piston for internal combustion engine

Abstract

A piston and an engine are provided that includes various precise configuration parameters, including dimensions, shape and/or relative positioning of combustion chamber features. More particularly, configuration parameters for a piston crown and a piston bowl located within the piston crown are provided. The piston bowl configuration results in a combustion process that yields decreased heat transfer to a cylinder head of the internal combustion engine as well as reduced NOx emissions.

We claim: 
     
       1. An internal combustion engine, comprising:
 an engine body; 
 a cylinder head attached to the engine body; 
 a combustion chamber positioned between the cylinder head and the engine body; and 
 a piston, including a piston crown that forms a portion of the combustion chamber, located in the engine body, the piston crown including a central axis, 
 a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, 
 an uppermost surface portion, and 
 a piston bowl positioned radially inward from the valve pockets, the piston bowl including: 
 a compound radius including a radius R 1 , radius R 1  including a center of radius at a radial distance L 1  from the central axis, radius R 1  connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl; 
 a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L 4  from the compound radius at an angle of to a plane perpendicular to the central axis; 
 an annular outer bowl portion including a radius R 5 ; and 
 a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R 3  with a center of radius located at an axial distance H 3  from the valve pockets, 
 wherein each of the valve pockets includes a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion; 
 wherein a ratio L4/R3 is in the range of 0.2 to 3.0. 
 
     
     
       2. The internal combustion engine of  claim 1 , wherein a ratio L 4 /R 3  is in the range of 0.2 to 3.0. 
     
     
       3. The internal combustion engine of claim  2  1, wherein a ratio of H 3 /L 1  is in the range of 0.15 to 0.3. 
     
     
       4. The internal combustion engine of  claim 3 , wherein α 1  is less than 60 degrees. 
     
     
       5. The internal combustion engine of  claim 1 , wherein a ratio of H 3 /L 1  is in the range of 0.15 to 0.3. 
     
     
       6. The internal combustion engine of  claim 5 , wherein α 1  is less than 60 degrees. 
     
     
       7. The internal combustion engine of  claim 1 , wherein α 1  is less than 60 degrees. 
     
     
       8. The internal combustion engine of  claim 1 , the piston bowl further including a ski jump feature located radially inward from the annular outer bowl portion, the ski jump feature tangentially connected to the annular outer bowl portion and including a radius R 4 . 
     
     
       9. The internal combustion engine of  claim 8 , wherein a ratio R 5 /R 4  is in the range of 2.5 to 5.0. 
     
     
       10. The internal combustion engine of  claim 9 , wherein a ratio L 4 /R 3  is in the range of 0.2 to 3.0. 
     
     
       11. The internal combustion engine of  claim 10 , wherein a ratio of H 3 /L 1  is in the range of 0.15 to 0.3. 
     
     
       12. The internal combustion engine of  claim 11 , wherein α 1  is less than 60 degrees. 
     
     
       13. The internal combustion engine of  claim 9 , wherein a ratio of H 3 /L 1  is in the range of 0.15 to 0.3. 
     
     
       14. The internal combustion engine of  claim 13 , wherein α 1  is less than 60 degrees. 
     
     
       15. The internal combustion engine of  claim 9 , wherein α 1  is less than 60 degrees. 
     
     
       16. An internal combustion engine, comprising:
 an engine body; 
 a cylinder head attached to the engine body; 
 a combustion chamber positioned between the cylinder head and the engine body; and 
 a piston, including a piston crown that forms a portion of the combustion chamber, located in the engine body, the piston crown including a central axis, an uppermost surface portion, a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and a piston bowl positioned radially inward from the valve pockets, the piston bowl including: a compound radius including a radius R 1 , radius R 1  including a center of radius at a radial distance L 1  from the central axis, radius R 1  connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl; a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L 4  from the compound radius at an angle α 1  to a plane perpendicular to the central axis; an annular outer bowl portion; and a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R 3  with a center of radius located at an axial distance H 3  from the end surface, each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion; 
 wherein a ratio L 4 /R 3  is in the range of 0.2 to 3.0 and a ratio H 3 /L 1  is in the range of 0.15 to 0.3. 
 
     
     
       17. The internal combustion engine of  claim 16 , wherein α 1  is less than 60 degrees. 
     
     
       18. An internal combustion engine, comprising:
 an engine body; 
 a cylinder head attached to the engine body; 
 a combustion chamber positioned between the cylinder head and the engine body; and 
 a piston, including a piston crown that forms a portion of the combustion chamber, located in the engine body, the piston crown including a central axis, an uppermost surface portion, a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and a piston bowl positioned radially inward from the valve pockets, the piston bowl including:
 a compound radius connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl; 
 a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending from the compound radius at an angle α 1  to a plane perpendicular to the central axis; 
 
 an annular outer bowl portion including a radius R 5 ;
 a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion; and 
 a ski jump feature positioned between the annular outer bowl portion and the central axis and connected to the angular outer bowl portion, the ski jump feature including a radius R 4 , 
 
 each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion: 
 wherein a ratio R 5 /R 4  is in the range of 2.5 to 5.0. 
 
     
     
       19. The internal combustion engine of  claim 18 , wherein angle α 1  is less than 60 degrees. 
     
     
       20. The internal combustion engine of  claim 19 , wherein the frustoconical outer floor portion extends radially outward a distance L 4  at an angle α 1  and the spray-targeting feature has a radius R 3  and a ratio L 4 /R 3  is in the range of 0.2 to 3.0. 
     
     
       21. A piston, comprising:
 a piston crown including a central axis,   a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis,   an uppermost surface portion, and   a piston bowl positioned radially inward from the valve pockets, the piston bowl including:   a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;   a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L4 from the compound radius at an angle α1 to a plane perpendicular to the central axis;   an annular outer bowl portion including a radius R5; and a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R3 with a center of radius located at an axial distance H3 from the valve pockets,   wherein each of the valve pockets includes a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion;   wherein a ratio of H3/L1 is in the range of 0.15 to 0.3.   
     
     
       22. The piston of claim 21, wherein a ratio L4/R3 is in the range of 0.2 to 3.0. 
     
     
       23. The piston of claim 21, wherein α1 is less than 60 degrees. 
     
     
       24. The piston of claim 21, the piston bowl further including a ski jump feature located radially inward from the annular outer bowl portion, the ski jump feature tangentially connected to the annular outer bowl portion and including a radius R4. 
     
     
       25. A piston, comprising:
 a piston crown including a central axis, an uppermost surface portion,   a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and   a piston bowl positioned radially inward from the valve pockets, the piston bowl including:   a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl;   a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L4 from the compound radius at an angle α1 to a plane perpendicular to the central axis; an annular outer bowl portion; and   a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R3 with a center of radius located at an axial distance H3 from the end surface, each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion; wherein a ratio L4/R3 is in the range of 0.2 to 3.0 and a ratio H3/L1 is in the range of 0.15 to 0.3.   
     
     
       26. The piston of claim 25, wherein α1 is less than 60 degrees. 
     
     
       27. A piston, comprising:
 a piston crown including a central axis, an uppermost surface portion,   a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis, and   a piston bowl positioned radially inward from the valve pockets, the piston bowl including:
 a compound radius connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl; 
 a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending from the compound radius at an angle α1 to a plane perpendicular to the central axis; 
 an annular outer bowl portion including a radius R5; 
 a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion; and 
 a ski jump feature positioned between the annular outer bowl portion and the central axis and connected to the annular outer bowl portion, the ski jump feature including a radius R4, 
   each of the valve pockets including a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion; wherein a ratio R5/R4 is in the range of 2.5 to 5.0.   
     
     
       28. The piston of claim 27, wherein angle α1 is less than 60 degrees. 
     
     
       29. The piston of claim 28, wherein the frustoconical outer floor portion
 extends radially outward a distance L4 at an angle α1 and the spray-targeting feature has a radius R3 and a ratio L4/R3 is in the range of 0.2 to 3.0.   
     
     
       30. A piston, comprising:
 a piston crown including a central axis,   a plurality of valve pockets arranged about the periphery of the piston crown in a plane perpendicular to the central axis,   an uppermost surface portion, and   a piston bowl positioned radially inward from the valve pockets, the piston bowl including:
 a compound radius including a radius R1, radius R1 including a center of radius at a radial distance L1 from the central axis, radius R1 connected to and extending inwardly from the valve pockets to form a smooth transition between the valve pockets and the piston bowl; 
 a frustoconical outer floor portion connected to the compound radius, the frustoconical outer floor portion extending a distance L4 from the compound radius at an angle α1 to a plane perpendicular to the central axis; 
 an annular outer bowl portion including a radius R5; 
 a spray-targeting feature positioned between the annular outer bowl portion and the frustoconical outer floor portion and including a radius R3 with a center of radius located at an axial distance H3 from the valve pockets; and 
 a frustoconical segment positioned between the spray-targeting feature and the annular outer bowl portion to prevent an undercut in the piston bowl; 
   wherein each of the valve pockets includes a rolled edge extending between the valve pocket and the uppermost surface portion, the rolled edge including a radius to form a smooth transition between the valve pocket and the uppermost surface portion.