When an amount of a backward tumble flow is smaller than an amount of a forward tumble flow, the intake-side valve recess is used as a first valve recess and the exhaust-side valve recess is used as a second valve recess. When the amount of the backward tumble flow is larger than the amount of the forward tumble flow, the exhaust-side valve recess is used as a first valve recess and the intake-side valve recess is used as a second valve recess. An inclination angle of the first valve recess is larger than an inclination angle of the second valve recess when comparing the inclination angle such that a height of the recess decreases gradually toward an inner side of a cross-section.

A cavity provided at a crown surface of a piston includes a first cavity section provided in a central area in a radial direction, a second cavity section provided outside the first cavity section, and a lip provided to connect the first-and-second cavity sections. Plural injection holes of an injector include a first injection-hole group where plural first injection holes directed toward a part close to the piston in a cylinder-axis direction are provided in a ring shape and a second injection-hole group where plural second injection holes directed toward a part close to a ceiling surface of a combustion chamber in the cylinder-axis direction are provided in the ring shape. The first injection-hole group and the second injection-hole group are positioned so as to inject fuel toward the lip concurrently.

A piston for an opposed-piston, internal combustion engine includes a crown with an end surface having a bowl shaped to form a combustion chamber with an end surface of an opposing piston in the opposed-piston engine. A substantially circumferential top land of the crown meets the end surface at a substantially circular peripheral edge, and a skirt comprising a sidewall extends from a substantially circumferential belt region of the crown. A wristpin bore with a wristpin axis opens through the sidewall. The end surface of the piston includes a pair of injection regions across which fuel is injected into the bowl. The injection regions are disposed in substantially diametrically-opposed quadrants of the end surface which are defined by the wristpin axis and a connecting rod envelope axis substantially orthogonal to the wristpin axis. Each injection region extends along a respective arc concentric with the substantially circular peripheral edge.

A piston combustion chamber structure of an engine includes two or more independent combustion chambers separated from each other and dented on an upper portion of a piston head in axial and circumferential directions. Each of the two or more independent combustion chambers comprises an outer wall and a bottom surface. Independent combustion chambers adjacent to each other among the two or more independent combustion chambers are partitioned by a partition wall. The partition wall has a slant surface such that a squish flowing in the circumferential direction can be generated.

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, and a pair of raised portions. The cavity includes a bottom portion which is a lower region of the recessed part, the bottom portion having an outer circumferential edge which is circular in a top view. With a height of the raised portion relative to a height position of a deepest portion of the cavity being represented as H1 and a diameter of an outer circumferential edge of the bottom portion of the cavity being represented as D, H1/D as a ratio of the height H1 of the raised portion to the diameter D of the cavity is set to be in a range of 0.05 or more and 0.36 or less.

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.

Methods and systems are provided for a piston. In one example, a system may comprise a plurality of first protrusions and a plurality of second protrusions working in tandem to confine an injection to a radial zone defined by the protrusions.

Method, control unit, and target arrangement of a leading vehicle for triggering a follower vehicle, which is situated at a lateral distance from the leading vehicle, to coordinate its movements with the leading vehicle. The target arrangement comprises a target configured to be placed at a lateral distance from to the leading vehicle. The target is also configured to be recognized by at least one forwardly directed sensor of the follower vehicle.

A component of a piston may include a crown portion configured to face a flame deck surface disposed at one end of a cylinder bore in which the piston is configured to reciprocate, such that a combustion chamber is defined within the cylinder bore and between a top surface of the crown portion and the flame deck surface. The component may include an indent formed in the top surface. The indent may be aligned with a fuel jet centerline along which a fuel jet is to be injected into the combustion chamber. The indent may include a first arcuate indent portion, that curves in a first direction from a center of the crown portion, and a second arcuate indent portion that curves in a second direction from a break in a reentrant feature that overhangs the first arcuate indent portion. The component may be included in an internal combustion engine.

A piston for an internal combustion engine includes a crown portion having a bowl that includes a plurality of protrusions. Each of the plurality of protrusions includes a first side surface and a second side surface. Other features including at least one ledge formed between protrusions in segments, and a generally flat, inward facing surface on the protrusions may also be used.