Piston assembly with opposing injection regions for an opposed-piston engine

Abstract

A piston for an opposed-piston, internal combustion engine includes a crown with an end surface having a bowl shaped to form a combustion chamber with an end surface of an opposing piston in the opposed-piston engine. A substantially circumferential top land of the crown meets the end surface at a substantially circular peripheral edge, and a skirt comprising a sidewall extends from a substantially circumferential belt region of the crown. A wristpin bore with a wristpin axis opens through the sidewall. The end surface of the piston includes a pair of injection regions across which fuel is injected into the bowl. The injection regions are disposed in substantially diametrically-opposed quadrants of the end surface which are defined by the wristpin axis and a connecting rod envelope axis substantially orthogonal to the wristpin axis. Each injection region extends along a respective arc concentric with the substantially circular peripheral edge.

1 . A piston for an opposed-piston engine, comprising:
 a crown with an end surface comprising a bowl configured to form a combustion chamber in cooperation with an adjacent end surface of an opposing piston;   a substantially circumferential top land of the crown which meets the end surface at a substantially circular peripheral edge;   a skirt comprising a sidewall extending away from the crown;   a wristpin bore that opens through the sidewall, the wristpin bore having a wristpin bore axis;   the wristpin bore configured to receive a wristpin that couples the piston to a connecting rod that swings in an envelope of motion defined by an envelope axis, the envelope axis being substantially orthogonal to the wristpin bore axis; and,   the end surface including a pair of injection regions across which fuel is injected into the bowl;   in which the injection regions are disposed in respective diametrically-opposed quadrants of the end surface, the diametrically-opposed quadrants being defined by the wristpin bore axis and the envelope axis; and,   in which each injection region extends along a respective arc concentric with the substantially circular peripheral edge.   
     
     
         2 . The piston of  claim 1 , the wristpin bore comprising a first opening formed in a first pin boss in the sidewall and a second opening formed in a second pin boss in the sidewall, the openings being coaxially aligned along the wristpin bore axis. 
     
     
         3 . The piston of  claim 1 , the end surface further comprising a pair of injection trenches, each injection trench being formed in a respective injection region and extending from the substantially circular peripheral edge to the bowl. 
     
     
         4 . The piston of  claim 3 , in which the injection trenches are situated in diametrically opposed locations. 
     
     
         5 . The piston of  claim 1 , the end surface further comprising two diametrically-opposed injection trenches, each injection trench being formed in a respective injection region and being shaped for guiding a spray of injected fuel into the bowl. 
     
     
         6 . The piston of  claim 1 , the crown further comprising an interior annular cooling gallery defined at least partially by an inner surface of the substantially circumferential top land, and inlet passageways positioned in the interior annular cooling gallery substantially in alignment with the injection trenches. 
     
     
         7 . The piston of  claim 6 , the wristpin bore comprising a first opening formed in a first pin boss in the sidewall and a second opening formed in a second pin boss in the sidewall, the openings being coaxially aligned along the wristpin bore axis. 
     
     
         8 . The piston of  claim 6 , the end surface further comprising two diametrically-opposed injection trenches, each injection trench being formed in a respective injection region and being shaped for guiding a spray of injected fuel into the bowl. 
     
     
         9 . The piston of  claim 8 , in which the injection trenches are situated in diametrically opposed locations. 
     
     
         10 . The piston of  claim 6 , in which the arcuate extent of each injection region subtends an angle of about 50-70 degrees with the vertex of the angle being at the center of the substantially circular peripheral edge. 
     
     
         11 . The piston of  claim 1 , in which the arcuate extent of each injection region subtends an angle of about 50-70 degrees with the vertex of the angle being at the center of the substantially circular peripheral edge. 
     
     
         12 . A piston assembly for an opposed-piston engine, comprising:
 a crown with an end surface comprising a bowl configured to form a combustion chamber in cooperation with an adjacent end surface of an opposing piston;   a substantially circumferential top land of the crown which meets the end surface at a substantially circular peripheral edge;   a skirt comprising a sidewall extending away from the crown;   a wristpin bore in the sidewall;   a wristpin with a wristpin axis received in the wristpin bore;   a connecting rod coupled to the wristpin for swinging in an envelope of motion defined by an envelope axis, the envelope axis being substantially orthogonal to the wristpin axis;   a pair of injection trenches in the end surface at the substantially circular peripheral edge through which fuel is injected into the bowl; and,   the injection trenches being situated in respective diametrically-opposed quadrants of the end surface defined by the wristpin axis and the envelope axis.   
     
     
         13 . The piston assembly of  claim 12 , the wristpin bore comprising a first opening formed in a first pin boss in the sidewall and a second opening formed in a second pin boss in the sidewall, the openings being coaxially aligned along the wristpin axis. 
     
     
         14 . The piston assembly of  claim 12 , each injection trench extending from the substantially circular peripheral edge to the bowl. 
     
     
         15 . The piston assembly of  claim 14 , in which the injection trenches are situated in diametrically opposed locations of the end surface. 
     
     
         16 . The piston assembly of  claim 12 , each injection trench being shaped for guiding a spray of injected fuel into the bowl. 
     
     
         17 . The piston assembly of  claim 12 , the crown further comprising an interior annular cooling gallery defined at least partially by an inner surface of the substantially circumferential top land region and inlet passageways positioned in the interior annular cooling gallery substantially in alignment with the injection trenches. 
     
     
         18 . The piston assembly of  claim 17 , the wristpin bore comprising a first opening formed in a first pin boss in the sidewall and a second opening formed in a second pin boss in the sidewall, the openings being coaxially aligned along the wristpin axis. 
     
     
         19 . The piston assembly of  claim 18 , each injection trench extending from the substantially circular peripheral edge to the bowl. 
     
     
         20 . The piston assembly of  claim 19 , in which the injection trenches are situated in diametrically opposed locations of the end surface. 
     
     
         21 . The piston assembly of  claim 12 , in which the injection trenches are positioned along respective arcuate portions of the substantially circular peripheral edge, each arcuate portion spanning about 70° and being substantially centered in one of the diametrically-opposed quadrants. 
     
     
         22 . An opposed-piston engine, comprising:
 a cylinder block with a plurality of cylinders disposed in an inline array along a length of the cylinder block;   a pair of pistons disposed in opposition in each cylinder;   each piston comprising a wristpin with a wristpin axis, the wristpin coupling the piston to a connecting rod that swings in a connecting rod motion envelope having an envelope axis that is substantially orthogonal to the wristpin axis, the piston further comprising a crown with an end surface and a bowl in the end surface configured to form a combustion chamber in cooperation with a bowl of an adjacent end surface of an opposing piston, the end surface including a pair of injection regions across which fuel is injected into the bowl;   in which the injection regions are disposed in respective diametrically-opposed quadrants of the end surface, the diametrically-opposed quadrants being defined by the wristpin axis and the envelope axis; and,   in which each injection region extends along a respective arc concentric with the substantially circular peripheral edge.   
     
     
         23 . The engine of  claim 22 , the wristpin bore comprising a first opening formed in a first pin boss in the sidewall and a second opening formed in a second pin boss in the sidewall, the openings being coaxially aligned along the wristpin axis. 
     
     
         24 . The engine of  claim 22 , the end surface further comprising a pair of injection trenches, each injection trench being formed in a respective injection region and extending from the substantially circular peripheral edge to the bowl. 
     
     
         25 . The engine of  claim 24 , in which the injection trenches are situated in diametrically opposed locations. 
     
     
         26 . The engine of  claim 22 , the end surface further comprising two diametrically opposed injection trenches, each injection trench being formed in a respective injection region and being shaped for guiding a spray of injected fuel into the bowl. 
     
     
         27 . The engine of  claim 22 , the crown further comprising an interior annular cooling gallery defined at least partially by an inner surface of a substantially circumferential top land of the crown, inlet passageways positioned in the interior annular cooling gallery in alignment with the injection regions. 
     
     
         28 . The engine of  claim 27 , the wristpin bore comprising a first opening formed in a first pin boss in the sidewall and a second opening formed in a second pin boss in the sidewall, the openings being coaxially aligned along the wristpin axis. 
     
     
         29 . The engine of  claim 27 , the end surface further comprising a pair of injection trenches, each injection trench being formed in a respective injection region and extending from the substantially circular peripheral edge to the bowl. 
     
     
         30 . The engine of  claim 29 , in which the injection trenches are situated in diametrically opposed locations. 
     
     
         31 . The engine of  claim 27 , the end surface further comprising two diametrically opposed injection trenches, each injection trench being formed in a respective injection region and being shaped for guiding a spray of injected fuel into the bowl. 
     
     
         32 . The engine of  claim 22 , in which the arcuate extent of each injection region subtends an angle of about 50-70 degrees with the vertex of the angle being at the center of the substantially circular peripheral edge.