A piston may have an annular body including a crown portion defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, a plane containing the longitudinal axis and the radial direction, and a contoured combustion bowl. In the plane containing the longitudinal axis and the radial direction, the crown portion includes a radially outer squish surface, and a swirl pocket having a reentrant surface that extends axially downwardly and radially outwardly from the squish surface defining a tangent that forms a reentrant angle with the squish surface that ranges from 33.0 degrees to 37.0 degrees.

A piston may have an annular body including a crown portion defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, a plane containing the longitudinal axis and the radial direction, and a contoured combustion bowl. In the plane containing the longitudinal axis and the radial direction, the crown portion includes a radially outer squish surface, and a swirl pocket having a reentrant surface that extends axially downwardly and radially outwardly from the squish surface defining a tangent that forms a reentrant angle with the squish surface that ranges from 33.0 degrees to 37.0 degrees.

A power cylinder system for a reciprocating engine includes a piston configured to move within a cylinder of the reciprocating engine. The system also includes a groove extending circumferentially about the piston and configured to support a ring. An axially-facing surface of the groove has circumferential undulations at ambient temperatures that are configured to compensate for distortions to the groove caused by operation of the reciprocating engine.

A power cylinder system for a reciprocating engine includes a piston configured to move within a cylinder of the reciprocating engine. The system also includes a groove extending circumferentially about the piston and configured to support a ring. An axially-facing surface of the groove has circumferential undulations at ambient temperatures that are configured to compensate for distortions to the groove caused by operation of the reciprocating engine.

The present invention allows the air-fuel mixture to swirl in a combustion chamber to increase the power from the engine. Each engine cylinder contains a piston, a combustion chamber, and at least one intake valve, exhaust valve, and spark-plug. Also, the top of the piston head contains a hole that forms the entry point of a converging nozzle, where the air-fuel mixture is first directed downwards and then horizontally through intake nozzles onto ramps located on the inner walls of the combustion chamber that allows the air-fuel mixture to swirl in a counter-clock wise motion. This swirling effect causes a cyclone inside the combustion chamber that when ignited it results in an additional explosive force that drives the piston downwards with additional acceleration, which increase the power produced by the engine.

The present invention allows the air-fuel mixture to swirl in a combustion chamber to increase the power from the engine. Each engine cylinder contains a piston, a combustion chamber, and at least one intake valve, exhaust valve, and spark-plug. Also, the top of the piston head contains a hole that forms the entry point of a converging nozzle, where the air-fuel mixture is first directed downwards and then horizontally through intake nozzles onto ramps located on the inner walls of the combustion chamber that allows the air-fuel mixture to swirl in a counter-clock wise motion. This swirling effect causes a cyclone inside the combustion chamber that when ignited it results in an additional explosive force that drives the piston downwards with additional acceleration, which increase the power produced by the engine.

In an opposed-piston engine, a piston has a top land. The piston top land has a non-cylindrical shape which affords more clearance with a piston bore to thrust and anti-thrust sides than to front-facing and rear facing sides.

Apparatuses, systems and method for utilizing multi-zoned combustion chambers (and/or multiple combustion chambers) for achieving compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in an internal combustion engine are provided. In addition, improved apparatuses, systems and methods for achieving and/or controlling compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in a “Siamese cylinder” internal combustion engine are provided.

Apparatuses, systems and method for utilizing multi-zoned combustion chambers (and/or multiple combustion chambers) for achieving compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in an internal combustion engine are provided. In addition, improved apparatuses, systems and methods for achieving and/or controlling compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in a “Siamese cylinder” internal combustion engine are provided.

A crankshaft (1) for a crankcase scavenged two stroke piston engine (2) is disclosed. The crankshaft (1) is configured to rotate around a rotation axis (ax) during operation. The crankshaft (1) comprises a crankpin (3) configured to move in a crank plane (cp) during operation, and a first and a second counterweight (5, 7) arranged on either side (S1, S2) of the crank plane (cp). The first counterweight (5) has a first outer radius (r1) measured from the rotation axis (ax) and the second counterweight (7) has a second outer radius (r2) measured from the rotation axis (ax). The first outer radius (r1) is smaller than the second outer radius (r2). The present disclosure further relates to a power unit (10), a crankcase scavenged two stroke piston engine (2), and a hand-held power tool (20).