Abstract: A control device for a compression ignition engine includes a controller configured to operate an engine body by compression ignition combustion when the engine body operates in a compression ignition range. When the engine body operates in a low load range with a load lower than a predetermined load in the compression ignition range, the controller sets a time of fuel injection with the fuel injection valve in a first half of a compression stroke or earlier, and allows the ozonator to introduce the ozone into the cylinder. When the engine body operates in the low load range, the controller controls an ozone concentration to be lower at a higher speed than at a low speed.

Abstract: A control device for a compression ignition engine includes a controller configured to operate an engine body by compression ignition combustion when the engine body operates in a predetermined compression ignition range. When the engine body operates in a predetermined high load range of the compression ignition range, the controller maximizes a filling amount of the cylinder using a gas state adjustment system, and lowers an EGR ratio so that the air-fuel mixture in the cylinder is lean with an excess air ratio ? higher than 1 in a lower speed range, and maximizes the filling amount of the cylinder, and increases the EGR ratio so that the air-fuel mixture in the cylinder has the excess air ratio ? of 1 or lower in a higher speed range than the lower speed range.

Abstract: A control device compression-ignition type engine that compression-ignites an air-fuel mixture in cylinders by introducing ozone into the cylinders at a predetermined operating range is provided. The control device detects a first ignition timing of an air-fuel mixture when introducing an intake of a first ozone concentration into the cylinders, detects a second ignition timing of the air-fuel mixture when introducing an intake of a second ozone concentration that differs from the first ozone concentration, and determines the fuel ignition ability based on a difference between the detected first ignition timing and the detected second ignition timing.

Abstract: A combustion chamber structure for an engine is provided. The structure includes a piston formed with a downward dented cavity in a central part of an upper surface thereof, and a cylinder head forming a combustion chamber having a pent-roof shape. The upper surface of the piston has an annular part extending from an outer edge of the cavity to an outer edge of the upper surface, and surrounding the outer edge of the cavity. The annular part is formed with first and second piston upper surface portions. When the piston is at a top dead center, a ratio of a volume of a space formed between the first piston upper surface portion and a bottom surface of the cylinder head with respect to a volume of a space formed between the second piston upper surface portion and the bottom surface becomes below a predetermined value.

Abstract: A control device of an engine is provided. The engine is operated at a high compression ratio, a geometric compression ratio of the engine being 14:1 or higher. The control device includes a fuel injection controller for controlling a fuel injector of the engine to start a fuel injection in a latter half of a compression stroke within an engine operating range where an engine speed is below a predetermined value and an engine load is above a predetermined value, and an ignition controller for controlling an ignition plug of the engine to retard an ignition timing when a timing for the fuel injection controller to start the fuel injection is on a retarding side of a predetermined timing, the ignition timing being retarded based on a retarding amount of the fuel injection start timing from the predetermined timing.

Abstract: A combustion chamber structure for an engine is provided. The combustion chamber structure includes a piston formed with a downward dented cavity at a central part of an upper surface thereof, and a fuel injector provided above the piston and on an extended line of a central axis of the piston, the fuel injector changing an injection timing of fuel on a compression stroke according to an operating state of the engine. A fuel injection angle of the fuel injector is designed to satisfy conditions in which the fuel is injected into the cavity and in which a fuel spray collision distance defined from a fuel injection position of the fuel injector to a collision position of the fuel with the cavity is longer than a breakup length defined from the fuel injection position of the fuel injector to a position where an initial breakup of the fuel occurs.

Abstract: Disclosed is an engine control system which is designed to allow homogeneous-charge compression ignition combustion to be performed in an HCCI region (R) defined as an engine operating region including at least a partial-load range of an engine. In a low load zone (R1) of the HCCI region (R), a lift amount of an intake valve (11) is set to a first predetermined value, and an exhaust valve (12) is allowed to start being opened during an intake stroke at a given timing later than an opening timing of the intake valve (11). Further, in the medium load zone of the HCCI region, the lift amount of the intake valve (11) is gradually increased up to a second predetermined value greater than the first predetermined value, along with an increase in an engine load. The engine control system is capable of adequately controlling an amount of burned gas to be introduced into a cylinder, depending on the engine load to allow the HCCI combustion to be adequately performed in a wider engine load range.

Abstract: Disclosed is an engine control system which is designed to allow homogeneous-charge compression ignition combustion to be performed in an HCCI region (R) defined as an engine operating region including at least a partial-load range of an engine. In a low load zone (R1) of the HCCI region (R), a lift amount of an intake valve (11) is set to a first predetermined value, and an exhaust valve (12) is allowed to start being opened during an intake stroke at a given timing later than an opening timing of the intake valve (11). Further, in the medium load zone of the HCCI region, the lift amount of the intake valve (11) is gradually increased up to a second predetermined value greater than the first predetermined value, along with an increase in an engine load. The engine control system is capable of adequately controlling an amount of burned gas to be introduced into a cylinder, depending on the engine load to allow the HCCI combustion to be adequately performed in a wider engine load range.

Abstract: When a specific condition requiring a rise in exhaust gas temperature is satisfied, a required fuel amount to be injected from an injector (21) is injected in a split manner, such that the fuel injection is divided to: a main injection (X1) to be initiated a given period before a compression top dead center; an auxiliary injection (X2) to be initiated after initiation of auto-ignited combustion of an air-fuel mixture consisting of air and the fuel injected by the main injection (X1) and before an assumed peak timing (Pk?) of a heat release rate (RH) from the combustion based on the main injection (X1); and a post injection (X3) to be initiated after the assumed peak timing (Pk?) and before completion of combustion based on the main injection (X1) and the auxiliary injection (X2). This makes it possible to raise an exhaust gas temperature while sufficiently ensuring auto-ignitability and fuel economy performance.