A method for operating an internal combustion engine of a motor vehicle having a cylinder, the combustion chamber of which is delimited in the radial direction by a cylinder wall and in the axial direction by a piston and by a combustion chamber roof. The piston has an annularly peripheral piston stage which is arranged axially recessed in the piston compared with an annularly peripheral piston crown and which merges via an annularly jet splitter contour into a piston hollow arranged axially recessed in the piston in relation to the piston stage. An injector is allocated to the cylinder and via the injector several injection jets are simultaneously injected directly into the combustion chamber in a star shape for a combustion process.

In a compression-ignition engine having a two-stage cavity, the distribution ratio between fuel for an upper cavity and fuel for a lower cavity is maintained even when the operational state of the engine changes. A piston of the compression-ignition engine includes a lower cavity, an upper cavity, and a lip portion between the lower cavity and the upper cavity. A controller causes a main injection and at least one pilot injection to be executed when the engine operates in a first state and a second state in which the load is higher than the load in the first state. The fuel spray is distributed to the lower cavity and the upper cavity. The controller causes a ratio of injection amount per pilot injection to the total injection amount to be higher when the engine operates in the second state than when the engine operates in the first state.

A piston for an internal combustion engine includes a piston body having a generally planar crown and a sidewall extending from the crown. A stepped combustion bowl is recessed in the crown and includes an outer bowl recessed relative to the crown and defining a generally planar annular floor surface. The stepped combustion bowl further includes an inner bowl recessed relative to the outer bowl. The inner bowl includes a sidewall that slopes continually inwardly from the outer bowl to a floor surface of the inner bowl. A plurality of protruding lips extend from the sidewall toward a central axis of the piston body.

A diesel engine includes at least one cylinder (1) with a piston (2) having a piston bowl (3). A fuel injector (6) is configured to direct a fuel spray towards a target area (21) on an annular wall section (22) of the piston bowl so as to make a flame (20) formed by ignition of the fuel spray hit the target area. The target area borders, via a flow separation edge (23), on a lowered flow separation area (24) on the annular wall section so as to give this annular wall section a stepped configuration. The flow separation edge and flow separation area are configured to induce the formation of a vortex-filled wake between the flame and the flow separation area on the downstream side of the flow separation edge when the flame flows from the target area, across the flow separation edge and over the flow separation area.

A diesel engine includes at least one cylinder (1) with a piston (2) having a piston bowl (3). A fuel injector (6) is configured to direct a fuel spray towards a target area (21) on an annular wall section (22) of the piston bowl so as to make a flame (20) formed by ignition of the fuel spray hit the target area. The target area borders, via a flow separation edge (23), on a lowered flow separation area (24) on the annular wall section so as to give this annular wall section a stepped configuration. The flow separation edge and flow separation area are configured to induce the formation of a vortex-filled wake between the flame and the flow separation area on the downstream side of the flow separation edge when the flame flows from the target area, across the flow separation edge and over the flow separation area.

Operating an internal combustion engine includes conveying fuel of spray plumes of directly injected fuel out of a swirl pocket in a combustion bowl in a piston, and impinging the fuel upon an anti-sooting ramp transitioning between a radially inner shelf surface of the combustion bowl and a radially outer squish surface of the piston. The shelf surface is spaced an axial distance (FA) from a plane defined by the squish surface that is from 1% to 2% of an outer diameter (OD) dimension of the piston. Impinging the fuel upon the anti-sooting ramp directs the fuel upwardly from the squish surface to limit wall-wetting in the combustion 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 combustion chamber structure for an engine includes a combustion chamber where SI combustion by spark ignition and CI combustion by self-ignition are conducted. A crown surface includes a cavity recessed to have a bowl-shape; a pair of first raised portions having a mound-shape along a pent roof shape; and a second raised portion provided to protrude at a position orthogonal to a ridge extending direction of the pair of first raised portions. With a height of the first raised portion relative to a height position of a deepest portion of the cavity being represented as H1 and a height of the second raised portion being represented as H2, H1/H2 as a ratio of the height H1 of the first raised portion to the height H2 of the second raised portion is set to be in a range of 1.92 or more and 2.75 or less.

A fuel injection device including a valve body having an injection hole-formed part having a plurality of injection holes on the leading end side of the valve body. An injection hole comprises a crossing angle, θ1, between a central axis of the injection hole-formed part and an injection hole axis, and another injection hole comprises a crossing angle, θ2, between the central axis and another injection hole axis. θ2 is larger than θ1. The injection holes are formed such that a distance between the central axis and an inlet surface center of the injection hole is longer than a distance between the central axis and another inlet surface center of the another injection hole. A straight line beyond an outlet surface in the injection hole axis does not intersect with another straight line beyond another outlet surface in the another injection hole axis.

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.