Cylinder and piston assemblies for opposed piston engines

A cylinder and piston combination for an opposed piston engine, comprising a cylinder and two pistons, in which

• the cylinder includes:
• a liner with a bore, an outside surface, and opposing ends;
• an exhaust port near an exhaust end of the liner;
• an inlet port near an inlet end of the liner;
• at least one fuel injector opening in a central portion of the liner;
• first liquid coolant grooves in the outside surface and extending from the central portion toward the exhaust end, the first liquid coolant grooves having a first cooling capacity;
• and,
• second liquid coolant grooves in the outside surface and extending from the central portion toward the inlet end, the second liquid coolant grooves having a second cooling capacity less than the first cooling capacity;
• each piston includes:
• a cylindrical skirt with a crown and an open end opposite the crown;
• a piston rod with a bore, a first, disc-shaped end attached to a back surface of the crown, and a second end extending through the open end of the skirt;
• a radial array of liquid coolant flow passages in communication with the bore and disposed between the disc-shaped end and the back surface of the crown;
• and,
• a single wristpin retained on the second end of the piston rod and positioned externally to the piston;
• and, the pistons are disposed crown-to-crown in the bore of the cylinder liner.

A method of operating an internal-combustion engine with a cylinder and a pair of opposed pistons disposed in a bore of the cylinder, each piston including a crown, the method comprising:

• applying a first amount of liquid coolant to a first portion of the cylinder extending from a central portion of the cylinder to an exhaust port of the cylinder;
• applying a second amount of liquid coolant to a second portion of the cylinder extending from the central portion to an inlet port of the cylinder;
• in which the first amount is greater than the second amount;
• applying radially symmetric streams of liquid coolant to a back surface of each piston crown;
• and,
• elastically deforming a compliant piston boot in response to a side force acting between the piston and the cylinder.