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: A control device of a spark-ignition gasoline engine is provided. The control device includes a controller for operating the engine body by controlling at least a fuel injection valve, an ignition plug, and a fuel pressure variable mechanism. Depending on the engine load range, the controller sets the combustion mode to a compression-ignition mode or a spark-ignition mode. In each mode, the controller also controls the fuel pressure, and the timing of fuel injection and ignition. The controller may also performs external EGR control in each mode.

Abstract: The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller controls a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection valve to perform a fuel injection at least at a timing that is more retarded than an injection timing of a fuel within the low engine load range and is within a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing within the retard period and further after the fuel injection.

Abstract: A spark-ignition direct injection engine is provided. The engine includes an engine body, a fuel injection valve, a fuel pressure setting mechanism, an ignition plug, and a controller. The controller operates the engine to perform compression-ignition combustion within a first operating range, and controls the ignition plug to operate the engine to perform spark-ignition combustion within a second operating range. Within a specific part of the first range, the controller sets the fuel pressure to 30 MPa or above, and retards the compression ignition to after a compression top dead center by controlling the injection valve to inject fuel into a cylinder in a period from a late stage of compression stroke to an early stage of expansion stroke. Below the specific part, the controller controls the fuel injection valve to inject the fuel into the cylinder in a period from intake stroke to a mid-stage of the compression stroke.

Abstract: A spark-ignition direct injection engine is provided. The engine includes an engine body, a fuel injection valve, a fuel pressure setting mechanism, an ignition plug, and a controller. Within a low engine speed operating range of a predetermined high engine load range, the fuel pressure setting mechanism sets a fuel pressure to 30 MPa or above, the fuel injection valve injects fuel between late stage of compression stroke and early stage of expansion stroke, and the ignition plug performs spark-ignition after the fuel injection completes. Within a high engine speed operating range of the high engine load range, the fuel injection valve injects fuel between intake stroke to mid-stage of compression stroke, and the ignition plug performs the spark-ignition. The ignition timing is changed according to an octane number, the changing width of the ignition timing is shorter within the low engine speed range than the high engine speed range.

Abstract: A spark-ignition engine is provided. The engine includes an engine body, a fuel injection valve, an ignition plug, an EGR introduction system, and a controller for operating the engine body by controlling the fuel injection valve, the ignition plug, and the EGR introduction system. The controller controls to combust mixture gas by compressing to self-ignite within a compression self-ignition combustion applying range, and to combust the mixture gas by a spark-ignition using the ignition plug within a spark-ignition combustion applying range. Substantially throughout the spark-ignition combustion applying range, the controller controls the EGR introduction system to introduce cooled EGR gas, and within the compression self-ignition applying range, the controller controls the EGR introduction system to introduce hot EGR gas. The controller controls the EGR introduction system to introduce the hot EGR gas and the cooled EGR gas within a low engine load part of the spark-ignition combustion applying range.

Abstract: The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller operates a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection mechanism to perform at least a fuel injection into the cylinder by a cylinder internal injection valve at a timing during a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing during the retard period and after the fuel injection.

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.

Abstract: The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller operates a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection mechanism to perform at least a fuel injection into the cylinder by a cylinder internal injection valve at a timing during a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing during the retard period and after the fuel injection.

Abstract: A control device of a spark-ignition gasoline engine is provided. The control device includes a controller for operating the engine body by controlling at least a fuel injection valve, an ignition plug, and a fuel pressure variable mechanism. Depending on the engine load range, the controller sets the combustion mode to a compression-ignition mode or a spark-ignition mode. In each mode, the controller also controls the fuel pressure, and the timing of fuel injection and ignition. The controller may also performs external EGR control in each mode.

Abstract: The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller controls a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection valve to perform a fuel injection at least at a timing that is more retarded than an injection timing of a fuel within the low engine load range and is within a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing within the retard period and further after the fuel injection.

Abstract: There is provided a spark ignited internal combustion engine having a geometric compression ratio of 13.0 or greater. The engine comprises combustion chambers having a cylinder stroke volume of 0.3 liter or greater, with the spark plug in the chamber ceiling having its spark point in the combustion chamber, and a cavity being formed on the top surface of the piston. At least part of the cavity defines a spherical surface that a hypothetical sphere having its center at the spark point contacts when the piston is at top dead center. The cavity is formed so that V2/V1?0.31, where V1 is top-dead-center combustion chamber volume, and V2 is the volume of the part of the hypothetical sphere not interfering with the combustion chamber floor or ceiling at top dead center. The flame thus spreads with less interference, shortening combustion duration and reducing fuel consumption.

Abstract: There is provided a spark ignited internal combustion engine having a geometric compression ratio of 13.0 or greater. The engine comprises combustion chambers having a cylinder stroke volume of 0.3 liter or greater, with the spark plug in the chamber ceiling having its spark point in the combustion chamber, and a cavity being formed on the top surface of the piston. At least part of the cavity defines a spherical surface that a hypothetical sphere having its center at the spark point contacts when the piston is at top dead center. The cavity is formed so that V2/V1?0.31, where V1 is top-dead-center combustion chamber volume, and V2 is the volume of the part of the hypothetical sphere not interfering with the combustion chamber floor or ceiling at top dead center. The flame thus spreads with less interference, shortening combustion duration and reducing fuel consumption.