Abstract: An object of the present invention is to provide a technology that enables to determine the cetane number of fuel in a state in which it is actually used for running an internal combustion engine with an improved degree of accuracy. A fuel injection for cetane number determination in which a specified quantity of fuel is injected into a combustion chamber during a compression stroke or expansion stroke, is performed while the internal combustion engine is in a fuel cut state. The cetane number of the fuel is determined based on the time period from a specified time to a time of ignition at which the fuel injected by the fuel injection for cetane number determination is ignited.

Abstract: Cylinders of a diesel engine 1 are provided with cylinder pressure sensors 29a to 29d for detecting combustion chamber pressures. An electronic control unit (ECU) 20 of the engine selects optimum combustion parameters in accordance with a fuel injection mode of fuel injectors 10a to 10d of the engine and a combustion mode determined by the amount of EGR gas supplied from the EGR valve 35 from among a plurality of types of combustion parameters expressing the combustion state of the engine calculated based on the cylinder pressure sensor output and feedback controls the fuel injection amount and fuel injection timing so that the values of the combustion parameters match target values determined in accordance with the engine operating conditions. Due to this, the engine combustion state is controlled to the optimum state at all times regardless of the fuel injection mode or combustion mode.

Abstract: Cylinders of a diesel engine 1 are provided with cylinder pressure sensors 29a to 29d for detecting combustion chamber pressures. An electronic control unit (ECU) 20 of the engine selects optimum combustion parameters in accordance with a fuel injection mode of fuel injectors 10a to 10d of the engine and a combustion mode determined by the amount of EGR gas supplied from the EGR valve 35 from among a plurality of types of combustion parameters expressing the combustion state of the engine calculated based on the cylinder pressure sensor output and feedback controls the fuel injection amount and fuel injection timing so that the values of the combustion parameters match target values determined in accordance with the engine operating conditions. Due to this, the engine combustion state is controlled to the optimum state at all times regardless of the fuel injection mode or combustion mode.

Abstract: An internal combustion is capable of switching, during engine operation, between a low-temperature combustion state in which an intake air with a high EGR rate is burned to operate the engine, and a normal combustion state in which an intake air with a low EGR rate is burned to operate the engine. In the internal combustion engine, a pilot injection is executed in addition to a main fuel injection, and furthermore the execution of the pilot injection is restricted during the engine operation with a combustion state switched to the low-temperature combustion state.

Abstract: An internal combustion is capable of switching, during engine operation, between a low-temperature combustion state in which an intake air with a high EGR rate is burned to operate the engine, and a normal combustion state in which an intake air with a low EGR rate is burned to operate the engine. In the internal combustion engine, a pilot injection is executed in addition to a main fuel injection, and furthermore the execution of the pilot injection is restricted during the engine operation with a combustion state switched to the low-temperature combustion state.

Abstract: There is provided a compression ignition type gasoline engine operable under a stable lean burn condition with a high compression ratio, and which has a simple construction without using a pre-heating system for an air-fuel mixture. An intake port communicates with a combustion chamber via an opening. The opening is closed by an intake valve. A fuel injection valve is provided in the intake port so as to inject an amount of gasoline inside the intake port within a duration in which the opening is substantially closed by the intake valve. Heat is generated in the mixture in the combustion chamber by means of a high compression ratio so that the mixture is self-ignited only by heat generated by compression. The compression ratio ranges from about 14 to about 20.

Abstract: A direct injection type internal combustion engine has a piston reciprocatably fitted in the bore of a cylinder block defining a combustion chamber together with the cylinder block and a cylinder head. A main recess is formed in the combustion chamber for accelerating the swirl of intake air which is prepared and introduced by an intake device. At least one auxiliary recess is formed in the main recess and is arranged in the direction of the intake air swirl and in the direction of the fuel injection of a fuel injector for generating a secondary swirl different from the intake air swirl and for generating turbulence between the two swirls. Thus, the introduction of air into the fuel droplets fed from the fuel injector is promoted by the intake air swirl and the secondary swirl so that the combustion efficiency of the internal combustion engine is improved.

Abstract: A direct injection internal combustion engine of a compression ignition type in which portions of an injected fuel spray which have not been evaporated are prevented from striking the walls of the combustion chamber, and the fuel spray is prevented from catching up the air around it when moving in the combustion chamber, thereby providing an engine having reduced combustion noise, reduced amount of smoke and noxious emissions, and improved fuel economy. A combustion chamber is formed in the piston substantially in the form of a spherical cavity gradually narrowing towards the opening of the cavity at the top surface of the piston. An air intake mechanism swirls intake air supplied to the combustion chamber. A swirl injector injects a fuel spray substantially in the form of a hollow cone having a velocity component in a direction tangential of the central axis of the nozzle.

Abstract: A direct injection internal combustion engine of compression ignition type is provided with a piston cavity offset from the piston center and with an injection nozzle which injects a hollow conical fuel spray having a tangential velocity component and relatively weak penetration into a swirl set up in the combustion chamber. The injection geometry and the offset are such that squish and swirl flows interact to form an excellent air-fuel mixture over the whole volume of the cavity without forming local fuel concentrations or wetting the cavity wall.

Abstract: A direct injection internal combustion engine of a compression ignition type uses swirl injection nozzle having relatively small penetration and relies on the combination of an intake swirl and compression squish flow as well as a substantial fuel spray angle to uniformly distribute fuel throughout the interior of a throttled combustion cavity recessed in the piston.

Abstract: A direct injection type internal combustion engine includes a centrifugal injector having its port facing a recess formed in a combustion chamber. The injector is arranged such that its axis of injection fails to intersect the central axis of the recess but extends at an inclination with respect to the same. In an embodiment typifying the invention, the following relationship is satisfied: ##EQU1## in which: D designates the maximum distance between facing sides of said recess; wherein with respect to a first transverse plane containing the location of the maximum distance D of said recess and a second plane intersecting said first transverse plane at a right angle, being parallel to the axis of sprays of the swirl injector and containing the center of the recess on the first transverse plane, .beta.