Abstract: A highly-efficient, yet simply constructed internal combustion engine includes an intake cylinder to accommodate intake and pre-compression of an oxidizing agent, a combustion cylinder to accommodate a further compression of the oxidizing agent, an injection and ignition of fuel, and a partial expansion of combustion gases produced by the ignition of fuel; and an exhaust cylinder to accommodate a further expansion of the combustion gases and subsequent exhausting of the further expanded combustion gases. A reciprocating piston is inside each of the intake, combustion and exhaust cylinders and a crankshaft is coupled to the reciprocating pistons. A first transfer passage facilitates flow of the pre-compressed oxidizing agent from the intake cylinder to the combustion cylinder and a second transfer passage facilitates flow of the partially-expanded combustion gases from the combustion cylinder to the exhaust cylinder.

Abstract: A highly-efficient, yet simply constructed internal combustion engine includes an intake cylinder to accommodate intake and pre-compression of an oxidizing agent, a combustion cylinder to accommodate a further compression of the oxidizing agent, an injection and ignition of fuel, and a partial expansion of combustion gases produced by the ignition of fuel; and an exhaust cylinder to accommodate a further expansion of the combustion gases and subsequent exhausting of the further expanded combustion gases. A reciprocating piston is inside each of the intake, combustion and exhaust cylinders and a crankshaft is coupled to the reciprocating pistons. A first transfer passage facilitates flow of the pre-compressed oxidizing agent from the intake cylinder to the combustion cylinder and a second transfer passage facilitates flow of the partially-expanded combustion gases from the combustion cylinder to the exhaust cylinder.

Abstract: A highly-efficient, yet simply constructed internal combustion engine includes an intake cylinder to accommodate intake and pre-compression of an oxidizing agent, a combustion cylinder to accommodate a further compression of the oxidizing agent, an injection and ignition of fuel, and a partial expansion of combustion gases produced by the ignition of fuel; and an exhaust cylinder to accommodate a further expansion of the combustion gases and subsequent exhausting of the further expanded combustion gases. A reciprocating piston is inside each of the intake, combustion and exhaust cylinders and a crankshaft is coupled to the reciprocating pistons. A first transfer passage facilitates flow of the pre-compressed oxidizing agent from the intake cylinder to the combustion cylinder and a second transfer passage facilitates flow of the partially-expanded combustion gases from the combustion cylinder to the exhaust cylinder.

Abstract: An engine has an engine casing with one or more surfaces that define a first substantially tubular coolant passage (e.g., a coolant inlet passage) with an open end that opens inside the engine casing. A first piston assembly is inside the engine casing and configured to reciprocate relative to the engine casing when the engine is operating. The first piston assembly has one or more surfaces that define a piston coolant jacket inside the first piston assembly. The piston coolant jacket has a first opening at an outer surface of the first piston assembly. A first fluid communication conduit extends between the engine casing and the first piston assembly and has a first end that is rigidly coupled to the first opening in the piston coolant jacket and a second end that extends through the open end of the first substantially tubular coolant passage in the engine casing.

Abstract: An engine has a stationary first body portion with one or more surfaces that define a portion of a fluid flow path through the engine. The stationary first body portion has a substantially cylindrical outer surface. A first piston assembly is configured to reciprocate relative to the stationary first body portion and to accommodate one or more second piston assemblies reciprocating inside and relative to the first piston assembly. The first piston assembly has an extension portion. The extension portion has a substantially cylindrical inner surface that defines a space to receive the stationary first body portion. One or more sealing elements are between the substantially cylindrical outer surface of the stationary first body portion and the extension portion of the first piston assembly.

Abstract: An engine includes an engine casing and a first piston configured to reciprocate relative to the engine casing. The first piston has a wall that defines a substantially cylindrical chamber. One or more second pistons are configured to reciprocate inside the substantially cylindrical chamber. A combustion chamber intake port and a combustion chamber exhaust port extend through the wall. A shutter is outside the wall and is movable between a first position substantially blocking fluid flow through the combustion chamber exhaust port but not blocking fluid flow through the combustion chamber intake port and a second position substantially blocking fluid flow through the combustion chamber intake port but not blocking flow through the combustion chamber exhaust port. An actuator causes the shutter to move between the first position and the second position in response to the first piston reciprocating relative to the engine casing.

Abstract: An engine has a stationary first body portion with one or more surfaces that define a portion of a fluid flow path through the engine. The stationary first body portion has a substantially cylindrical outer surface. A first piston assembly is configured to reciprocate relative to the stationary first body portion and to accommodate one or more second piston assemblies reciprocating inside and relative to the first piston assembly. The first piston assembly has an extension portion. The extension portion has a substantially cylindrical inner surface that defines a space to receive the stationary first body portion. One or more sealing elements are between the substantially cylindrical outer surface of the stationary first body portion and the extension portion of the first piston assembly.

Abstract: An engine includes an engine casing and a first piston configured to reciprocate relative to the engine casing. The first piston has a wall that defines a substantially cylindrical chamber. One or more second pistons are configured to reciprocate inside the substantially cylindrical chamber. A combustion chamber intake port and a combustion chamber exhaust port extend through the wall. A shutter is outside the wall and is movable between a first position substantially blocking fluid flow through the combustion chamber exhaust port but not blocking fluid flow through the combustion chamber intake port and a second position substantially blocking fluid flow through the combustion chamber intake port but not blocking flow through the combustion chamber exhaust port. An actuator causes the shutter to move between the first position and the second position in response to the first piston reciprocating relative to the engine casing.

Abstract: An engine has an engine casing with one or more surfaces that define a first substantially tubular coolant passage (e.g., a coolant inlet passage) with an open end that opens inside the engine casing. A first piston assembly is inside the engine casing and configured to reciprocate relative to the engine casing when the engine is operating. The first piston assembly has one or more surfaces that define a piston coolant jacket inside the first piston assembly. The piston coolant jacket has a first opening at an outer surface of the first piston assembly. A first fluid communication conduit extends between the engine casing and the first piston assembly and has a first end that is rigidly coupled to the first opening in the piston coolant jacket and a second end that extends through the open end of the first substantially tubular coolant passage in the engine casing.

Abstract: An engine includes a fuel injector support element to support a fuel injector and define a first opening through which the fuel injector can inject fuel. A first piston defines a substantially cylindrical inner chamber and a portal into the substantially cylindrical inner chamber. One or more second pistons are arranged to reciprocate inside the substantially cylindrical inner chamber and to define, in cooperation with the substantially cylindrical inner chamber, a combustion chamber. The first fuel injector support element and the first piston are arranged such that, during engine operation, the first piston reciprocates relative to the first fuel injector support element to thereby cause the first opening and the first portal to move in and out of alignment with one another.

Abstract: An engine includes a first piston with surfaces that define a substantially cylindrical chamber inside the first piston and a passage into the substantially cylindrical chamber. One or more second pistons are arranged to reciprocate inside the substantially cylindrical chamber and to define, in cooperation with the substantially cylindrical chamber, a combustion chamber. A fuel injector extends at least partially through the passage in the first piston to inject fuel into the combustion chamber. The first piston is arranged to move in a reciprocating manner relative to the fuel injector.

Abstract: An engine includes a fuel injector support element to support a fuel injector and define a first opening through which the fuel injector can inject fuel. A first piston defines a substantially cylindrical inner chamber and a portal into the substantially cylindrical inner chamber. One or more second pistons are arranged to reciprocate inside the substantially cylindrical inner chamber and to define, in cooperation with the substantially cylindrical inner chamber, a combustion chamber. The first fuel injector support element and the first piston are arranged such that, during engine operation, the first piston reciprocates relative to the first fuel injector support element to thereby cause the first opening and the first portal to move in and out of alignment with one another.

Abstract: An engine includes a first piston with surfaces that define a substantially cylindrical chamber inside the first piston and a passage into the substantially cylindrical chamber. One or more second pistons are arranged to reciprocate inside the substantially cylindrical chamber and to define, in cooperation with the substantially cylindrical chamber, a combustion chamber. A fuel injector extends at least partially through the passage in the first piston to inject fuel into the combustion chamber. The first piston is arranged to move in a reciprocating manner relative to the fuel injector.