In a combustion cycle in which fuel for forming a homogenized air-fuel mixture in the combustion chamber is injected from the first fuel injector, ignition-use fuel for forming an ignition-use air-fuel mixture in the vicinity of the electrode part is injected from the second fuel injector, and lean combustion is performed by an excess air rate of 2.0 or more, the ignition-use fuel is injected by at least an injection rate of 1.0 mm.sup.3/ms or more for a duration of 250 μs or more in an interval from a crank angle advanced by exactly 20 degrees from an ignition timing of the spark plug to the ignition timing, and the quantity of the ignition-use fuel is 2.0 mm.sup.3/st or less.

An engine operable in a premixed combustion system and a diffusion combustion system. The engine includes a main fuel injection valve, a pilot fuel injection valve, a liquid fuel tank, a main fuel supply path, a pilot fuel supply path, a pilot fuel filter, a pilot fuel high-pressure pump, a pilot fuel tank, and a pilot fuel supply pump. The pilot fuel tank stores pilot fuel sent from the pilot fuel high-pressure pump and not injected by the pilot fuel injection valve. This pilot fuel is sent to an automatic backwash filter and a pilot fuel filter while not passing through the liquid fuel tank.

Methods and systems for flex fuel engines that have both port fuel injection and direct injection. Operating an engine system includes determining a percent of ethanol in a fuel and determining whether the percent of ethanol is greater than a predetermined threshold. When the percent of ethanol is greater than the predetermined threshold, fuel is supplied only through the direct injection injectors. When the percent of ethanol is not greater than the predetermined threshold, fuel is supplied through a combination of the direct injection injectors and port fuel injection injectors.

A method provides for operating an engine configured to use a plurality of differing fuels. The method includes determining a fuel combustion ratio of the plurality of differing fuels associated with at least one engine cylinder of the engine based at least in part on one or more of a plurality of characteristic profiles. This maintains one or more of a plurality of actual values associated with usage of the plurality of differing fuels relative to defined corresponding threshold values. The fuel combustion ratio includes a ratio of the plurality of differing fuels to be delivered to the at least one engine cylinder. A fuel delivery system delivers the plurality of differing fuels to the at least one engine cylinder based on the fuel combustion ratio.

An injection device for an internal combustion engine having a first injection system for injecting fuel having a first fuel composition, and a second injection system for the injection of fuel having a second fuel composition that has a lower ethanol component than the first fuel composition, the first injection system having at least one first fuel injector for injecting fuel having the first fuel composition both in the direction of a first intake orifice of a combustion chamber of the internal combustion engine, and in the direction of a second intake orifice of the combustion chamber, in which the second injection system has a second fuel injector for injecting fuel having the second fuel composition essentially only in the direction of the first intake orifice, and a separate third fuel injector for injecting fuel having the second fuel composition essentially only in the direction of the second intake orifice.

Methods and systems are provided for a multi-fuel engine. In one example, a method includes adjusting a substitution ratio based on an intake manifold temperature. The method further including adjusting the intake manifold temperature to increase the substitution ratio.

Methods and systems are provided for adjusting a location of a fuel injection in response to a substitution rate and a desired EGR flow. In one example, a method may include injecting a first fuel to a combustion chamber via a direct injector positioned to inject directly into the combustion chamber, injecting a second, different, fuel to the combustion chamber via an exhaust port injector positioned to inject toward an exhaust valve of the combustion chamber, and combusting the first and second fuels together in the combustion chamber.

Various methods and systems are provided for using only hydrogen as fuel in a duel fuel engine. In one example, a method may include direct injecting only hydrogen as fuel to one or more engine cylinders and compression igniting the injected hydrogen.

An apparatus for controlling a gasoline-diesel complex combustion engine includes an engine generating driving torque by burning gasoline fuel and diesel fuel, a driving information detector for detecting driving information of the engine, and a controller for controlling a diesel injector such that diesel fuel is injected as a single injection or a split injection based on a driving region and a knock intensity included within the driving information.

Methods and systems are provided for injecting gaseous fuel during an engine start. In one example, a method comprises generating gaseous fuel via a fuel gasification device and injecting the gaseous fuel via a fuel injector. The fuel injector is configured to inject adjacent to an ignition device.