An internal combustion engine includes an auxiliary chamber bulkhead, the auxiliary chamber bulkhead including: a peripheral wall portion that is inserted in a vertical hole extending from a combustion chamber along a reference axis and that is in contact with an inner wall of the vertical hole about the reference axis; and a bottom wall portion that is continuous from the peripheral wall portion and that bulges from the vertical hole toward the combustion chamber, the peripheral wall portion and the bottom wall portion defining an auxiliary chamber that communicates with the combustion chamber. An ignition plug is disposed above the peripheral wall portion along the reference axis. A fuel injection valve is disposed in a position inclined with respect to the reference axis toward an opening formed in an inner surface of the peripheral wall portion.

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.

The invention relates to an air-compressing internal combustion engine, comprising at least one piston (1) having a combustion chamber trough (3) substantially rotationally symmetrical to a piston axis (2), which has a trough bottom (4) with a substantially cone-like elevation (5) and a circumferential trough wall (6), wherein the trough wall (6) forms a substantially torus-like first section (6a) having a maximum inner first trough diameter (d1), a second section (6b) having a minimum inner second trough diameter (d2) smaller than the inner first trough diameter (d1), and a third section (6c), whereinas seen in a meridian section of the piston (1)the first section (6a) has a concave first radius of curvature (R1) and the second section (6b) has a convex second radius of curvature (R2), and wherein the third section (6c) forms a first annular surface (8) adjoining the second section (6b) and a second annular surface (9) terminating in the piston end surface (7), which second annular surface (9) defines an angle () with the first annular surface (8), wherein the first annular surface (8) and the second annular surface (9) are formed to be inclined to a normal plane () on the piston axis (2), and wherein in the transition between the first annular surface (8) and second annular surface (9) an edge (11) is formed with a defined third radius of curvature (R3),

In order to prevent soot formation phenomena, it is provided that, as viewed in a meridian section of the piston (1), the first annular surface (8) together with a normal plane () on the piston axis (2) forms a first angle () between 10 and 20, preferably 15.2.

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 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 lower than the load in the first state. The fuel spray is distributed to the lower cavity and the upper cavity. The controller outputs a control signal to a fuel injection valve so that a distribution ratio for the upper cavity is higher when the engine operates in the second state than when in the first state.

A control device for a compression-ignition engine is provided, which includes an engine having a plurality of cylinders, spark plug, a fuel injector, and a control unit connected to the spark plug and the fuel injector. The control unit causes the engine to perform an all-cylinder operation when the engine operates at a load above a given load, and perform a reduced-cylinder operation at a load below the given load. In the reduced-cylinder operation, the fuel injector injects fuel to one or some of the cylinders to generate mixture gas, the spark plug ignites the mixture gas, and the engine starts, at an air-fuel ratio larger than a stoichiometric air-fuel ratio and a large compression ratio, SI combustion in which the mixture gas is ignited to combust by flame propagation, and then perform CI combustion in which unburned mixture gas ignites by self-ignition.

An engine system capable of controlling an intake air flow includes a combustion chamber, an ignition plug, an intake air flow control valve, and a controller. The controller performs, in at least a part of an operating range, SPCCI combustion in which after jump-spark ignition combustion of a portion of a mixture gas inside the combustion chamber by a jump-spark ignition of the ignition plug, compression ignition combustion of the remaining mixture gas is carried out by a self-ignition. The controller strengthens, at least in a part of the operating range of SPCCI combustion, the intake air flow inside the combustion chamber by controlling the intake air flow control valve. The controller controls, in a middle-load range of the operating range where SPCCI combustion is performed, the intake air flow control valve so that the intake air flow becomes weaker than in a high-load range and a low-load range.

A compression-ignition engine control system is provided, which includes an intake variable mechanism and a controller. Within a first operating range and a second operating range on a higher engine load side, the controller controls the variable mechanism to form a gas-fuel ratio (G/F) lean environment in which an air-fuel ratio inside a cylinder is near a stoichiometric air-fuel ratio and burnt gas remains inside the cylinder, and controls a spark plug to spark-ignite mixture gas inside the cylinder to combust in a partial compression-ignition combustion. The controller controls the variable mechanism to advance the intake valve open timing on an advancing side of a TDC of the exhaust stroke, as the engine load increases within the first range, and retard the intake valve open timing on the advancing side of the TDC of the exhaust stroke, as the engine load increases within the second range.

A method of implementing control logic of a compression-ignition engine is provided. A controller outputs a signal to a injector and a variable valve operating mechanism so that a gas-fuel ratio (G/F) becomes leaner than a stoichiometric air fuel ratio, and an air-fuel ratio (A/F) becomes equal to or richer than the stoichiometric air fuel ratio, and to an ignition plug so that unburnt mixture gas combusts by self-ignition after the ignition plug ignites mixture gas inside a combustion chamber. The method includes steps of determining a geometric compression ratio and determining the control logic defining an intake valve close timing IVC. IVC (deg.aBDC) is determined so that the following expression is satisfied: if the geometric compression ratio is 10<17,
0.4234.sup.222.926+207.84+CIVC0.4234.sup.2+22.926167.84+C
where C is a correction term according to an engine speed NE (rpm),
C=3.310.sup.10NE.sup.31.010.sup.6NE.sup.2+7.010.sup.4NE.

In an engine (1), when an intake valve (16) opens, a downstream end portion (61) of a first intake port (6) extends to direct to between a shade back (162a) positioned on a cylinder axis (C) side with respect to a valve stem (161) and a ceiling surface (51) facing the shade back (162a). As viewed in a section perpendicular to a direction perpendicular to an intake air flow direction, a second intake port side inner wall surface (61a) at the downstream end portion (61) of the first intake port (6) curves apart from a second intake port (7) in a direction from an exhaust side to an intake side as compared to the shape of an opposite second intake port side inner wall surface (61b) mirror-reversed to a second intake port (7) side.

The deterioration of combustion due to condensed water flowing into a cylinder is suppressed as much as possible. A control apparatus for an internal combustion engine is applied to an internal combustion engine which includes a fuel injection valve that directly injects fuel into a cylinder and a spark plug. The internal combustion engine is constructed so that the fuel goes to the spark plug. The control apparatus comprising a controller configured to: predict whether condensed water flows into the cylinder during an intake stroke; and carry out first injection control to perform fuel injection in a predetermined period of time within a period of time which is after closure of an exhaust valve and before the condensed water flows into the cylinder, and second injection control to perform fuel injection in a compression stroke before ignition, if an inflow of the condensed water into the cylinder is predicted.