The disclosure describes multipoint ignition systems for an engine and methods of operation of the same. The systems and methods can include an engine, including an engine block having at least one cylinder bore, a piston having a piston crown facing a flame deck surface such that a combustion main chamber is defined within a cylinder bore and located between the piston crown and the flame deck surface, the piston crown further including a piston bowl having a generally concave shape, and a combustion pre-chamber having a nozzle tip disposed in fluid communication with the combustion main chamber, the nozzle tip having at least one nozzle opening configured to inject a fuel jet into the combustion main chamber, wherein the piston includes a piston wall located around a circumference of the piston bowl, the piston wall including at least one cavity.

A piston is used for an engine including: an ignition plug disposed in the vicinity of a central axis of a cylinder; intake and exhaust ports disposed at positions where the ignition plug is interposed therebetween; and an injector disposed at a position offset from the ignition plug toward the intake port to inject fuel sprays toward a crown surface of the piston. The piston includes: a recess formed by recessing the crown surface of the piston with respect to other portions of the crown surface, in which the recess includes a step on an outer peripheral edge over the entire circumference thereof with respect to the other portions, and a pair of lateral sides formed straightly so as to extend substantially in parallel to a straight line connecting the injector and the ignition plug when seen in a direction of the cylinder axis.

A fuel injection apparatus includes: an injector disposed at a position offset from an ignition plug toward an intake port and injecting a fuel spray toward a crown surface of a piston, and an injection controller causing the injector to perform injection in accordance with an amount and timing of fuel injection preset in accordance with an operating state of an engine. The piston includes: a first recess formed by recessing a central portion of the crown surface and a second recess formed by recessing part of the first recess on an injector side further than the first recess. The injector injects 50% or more of fuel to be injected for the last fuel injection toward the second recess during a compression stroke, and injects part of the fuel to be injected for the last fuel injection toward an area of the first recess other than the second recess.

A method for producing a piston with a combustion bowl may include fastening an annular fibrous preform for reinforcing a periphery of the combustion bowl in a casting mold for the piston coaxially with a piston axis in a plane of a piston head. The method may also include introducing a metal melt into the casting mold to produce a piston blank, generating a pressure difference between the metal melt and the fibrous preform for infiltration of the metal melt into the fibrous preform, and machining the piston blank. The fibrous preform may be held in the casting mold by suction tubes in which a negative pressure may prevail such that the metal melt may be sucked into and infiltrate the fibrous preform. At least one section of at least one of the suction tubes may accelerate solidification of the metal melt passing into the suction tube.

An engine includes a piston movable within a combustion cylinder, a direct fuel injector, and a hotspot fuel igniter. The hotspot fuel igniter includes a core exposed to the combustion cylinder, to ignite fuel spray plumes of a directly injected fuel, and an insulator insulating the core from heat transfer with a material of the piston. Applications include igniting a range of fuels, including lower cetane number fuels.

A piston, comprising a crown, an insert having an outer ring, an inner ring, and at least one interconnection between the outer ring and the inner ring, and a skirt integrally formed with the crown through the insert so that the crown and skirt are made from a type of aluminum and the insert is made from a material other than aluminum.

An engine includes a piston movable within a combustion cylinder, a direct fuel injector, and a hotspot fuel igniter. The hotspot fuel igniter includes a core exposed to the combustion cylinder, to ignite fuel spray plumes of a directly injected fuel, and an insulator insulating the core from heat transfer with a material of the piston. Applications include igniting a range of fuels, including lower cetane number fuels.