An internal combustion engine for a vehicle is provided, having at least one cylinder with a first gas exchange inlet valve, a second gas exchange inlet valve, a first gas exchange outlet valve, a second gas exchange outlet valve, and a piston with a piston crown which has a plurality of valve seat pockets. In each case one valve seat pocket is provided for the first gas exchange inlet valve, the second gas exchange inlet valve, the first gas exchange outlet valve and the second gas exchange outlet valve, and the plurality of valve seat pockets have at least partially different depths. Alternatively, one valve seat pocket is provided for the first gas exchange inlet valve and the first gas exchange outlet valve, and no valve seat pocket is provided for the second gas exchange inlet valve and/or for the second gas exchange outlet valve.

A fuel and gas mixing structure for an engine is provided. This mixing structure includes a body configured to be positioned between a fuel injector and a cylinder of an engine. The body defines an interior volume that is configured to receive gas from outside the body and to receive one or more streams of fuel from the fuel injector in the interior volume. The body also defines one or more mixture conduits configured to conduct plumes of the fuel and gas, while mixing, from the interior volume to one or more exit ports and therethrough to the cylinder.

Operating an engine includes injecting a first charge of liquid fuel using a first set of nozzle outlets in a fuel injector, and injecting a second charge of liquid fuel using a second set of nozzle outlets in a fuel injector. The first charge is autoignited in a first engine cycle, and the second charge is autoignited in a second engine cycle, and may be used to pilot ignite a charge of gaseous fuel. Operating the engine further includes limiting errors in targeting of the second charge of liquid fuel caused by transitioning the engine from a first combination to a second combination of speed, load, and boost, by varying an injection pressure of the liquid fuel from the first engine cycle to the second engine cycle.

A cavity includes a lower-side cavity, an upper-side cavity, a first lip and a second lip. The upper-side cavity has a guide curved surface which extends along a circumference of a first imaginary circle in a section along a cylinder-axis direction, and the first lip has a curved surface which extends along a circumference of a second imaginary circle in a section along the cylinder-axis direction. An angle X which a cylinder axis makes with a common tangential line of the first imaginary circle and the second imaginary circle is set as 75°<X<80°. The guide curved surface is configured such that an angle Y of this guide curved surface which occupies at the circumference of the first imaginary circle is set as 80°<Y<(180°−X).

An enhanced piston for improving the efficiency of an internal combustion engine has a cylinder with a combustion chamber and a lower cylinder portion. A cylinder head is disposed on the cylinder. An enhanced piston is moveably disposed within the cylinder and is connected to a piston rod. The enhanced piston has a piston cavity. There is an upper piston valve connected to an upper piston valve rod. The upper piston valve is disposed within the piston cavity wherein the upper piston valve selectively seals said piston cavity from the combustion chamber. A piston cavity port is disposed on a bottom portion of the piston cavity and is selectively opened and closed with a lower piston valve. The lower piston valve seals the piston cavity port from the lower cylinder portion. This way the gases are selectively sealed in the piston cavity under pressure until released in the combustion chamber.

An enhanced piston for improving the efficiency of an internal combustion engine has a cylinder with a combustion chamber and a lower cylinder portion. A cylinder head is disposed on the cylinder. An enhanced piston is moveably disposed within the cylinder and is connected to a piston rod. The enhanced piston has a piston cavity. There is an upper piston valve connected to an upper piston valve rod. The upper piston valve is disposed within the piston cavity wherein the upper piston valve selectively seals said piston cavity from the combustion chamber. A piston cavity port is disposed on a bottom portion of the piston cavity and is selectively opened and closed with a lower piston valve. The lower piston valve seals the piston cavity port from the lower cylinder portion. This way the gases are selectively sealed in the piston cavity under pressure until released in the combustion chamber.

A fuel system for an internal combustion engine includes a fuel injector having a nozzle with first and second sets of spray orifices formed therein. The fuel injector also includes a first and a second outlet check movable to open and close the first and second sets of spray orifices. Spray plume ducts are supported at fixed orientations relative to a nozzle of the fuel injector, and each are oriented in-line with a center axis defined by one of the spray orifices. The spray plume ducts may be directly attached to the fuel injector or to a duct carrier mounted to an engine head.

An enhanced piston for improving the efficiency of an internal combustion engine has a cylinder with a combustion chamber and a lower cylinder portion. A cylinder head is disposed on the cylinder. An enhanced piston is moveably disposed within the cylinder and is connected to a piston rod. The enhanced piston has a piston cavity. There is an upper piston valve connected to an upper piston valve rod. The upper piston valve is disposed within the piston cavity wherein the upper piston valve selectively seals said piston cavity from the combustion chamber. A piston cavity port is disposed on a bottom portion of the piston cavity and is selectively opened and closed with a lower piston valve. The lower piston valve seals the piston cavity port from the lower cylinder portion. This way the gases are selectively sealed in the piston cavity under pressure until released in the combustion chamber.

An enhanced piston for improving the efficiency of an internal combustion engine has a cylinder with a combustion chamber and a lower cylinder portion. A cylinder head is disposed on the cylinder. An enhanced piston is moveably disposed within the cylinder and is connected to a piston rod. The enhanced piston has a piston cavity. There is an upper piston valve connected to an upper piston valve rod. The upper piston valve is disposed within the piston cavity wherein the upper piston valve selectively seals said piston cavity from the combustion chamber. A piston cavity port is disposed on a bottom portion of the piston cavity and is selectively opened and closed with a lower piston valve. The lower piston valve seals the piston cavity port from the lower cylinder portion. This way the gases are selectively sealed in the piston cavity under pressure until released in the combustion chamber.

A piston for an internal combustion engine includes a piston wall defining an outer perimeter of the piston, and a piston face located at an end of the piston wall. The piston face includes a radially-extending outer face, and a combustion bowl formed therein and recessed from the outer face. The combustion bowl includes an upper bowl including a flat upper bowl radial surface recessed from the outer face a distance in the range from 3.5 to 4.5 millimeters, and a lower bowl including a lower bowl surface recessed to a maximum bowl depth from the flat upper bowl axial surface in the range from 10.4 to 13.4 millimeters. The piston face is axisymmetric about a piston central axis.