Methods and systems are provided for re-combustion of exhaust in a cylinder of a multi-cylinder engine in order to increase the temperature of the exhaust for enhancing catalytic conversion within the multi-cylinder engine. In one example, a method may include expelling combusted gases from the cylinder into an intake manifold via an intake valve during an exhaust stroke, in order to rebreathe in the combusted gases from the intake manifold via the intake valve in a subsequent intake stroke.

Emission of unburned hydrocarbons and soot is reduced while ensuring startability (ignitability) in a cold start mode of an internal combustion engine. Thus, fuel is injected with a first injection rate as an injection rate of a fuel injection valve 100 in a warm state in which a temperature of an engine 30 is equal to or higher than a set temperature, and the fuel is injected with a second injection rate lower than the first injection rate as the injection rate of the fuel injection valve 100 in a cold state in which the temperature of the engine 30 is lower than the set temperature at the same fuel pressure as that in the warm state.

A method for controlling fuel injection aspects of a fuel system of an internal combustion engine includes determining a fuel injection strategy for each engine cycle including a pilot fuel injection, a main fuel injection, and a dwell time between the pilot and main fuel injections. The method also includes automatically adjusting the dwell time for each engine cycle based on a sensed ambient temperature and ambient pressure associated with the internal combustion engine.

A method to control the combustion of a compression ignition engine having the steps of: establishing, for each combustion cycle, a fuel quantity to be injected into the cylinder; injecting a first fraction of the fuel quantity; heating a second fraction of the fuel quantity, which is equal to the remaining fraction of the fuel quantity, to an injection temperature higher than 100° C.; injecting the second fraction of the fuel quantity heated to the injection temperature into the cylinder at the end of the compression stroke and at no more than 60° from the top dead centre; and decreasing the injection temperature and the ratio between the second fraction and the first fraction as the internal combustion engine increases and as the rotation speed of the internal combustion engine increases.

A control device for a compression ignition engine is provided, which causes an injector to perform a pre-injection and a main injection, sets fuel injection timings of these injections so that an interval between a first peak of a heat release rate resulting from the combustion of fuel injected by the pre-injection and a second peak of the heat release rate resulting from the combustion of fuel injected by the main injection becomes an interval to make pressure waves caused by these combustions cancel each other out, and when an increase of an intake air temperature is detected, controls the injector to reduce the injection amount of the pre-injection and retard the injection timing of the pre-injection compared with a case where the increase of the intake air temperature is not detected under a condition that engine load and speed are the same.

An engine control device is provided. A fuel injection valve performs a pre-injection and a main injection on a retarding side of the pre-injection so that pressure waves resulting from combustions caused by the injections cancel each other out. The control device secures a fuel injection amount to be supplied to a combustion chamber in one cycle by at least the pre-injection, the main injection, and a middle injection. The control device causes the fuel injection valve to perform the pre-injection at a timing when a piston is located at an advancing side of compression top dead center for premix combustion, to start the main injection during a combustion period of the fuel injected by the pre-injection for diffuse combustion, and to perform the middle injection at a timing between the other two injections with a fuel injection amount less than the other injections.

A control system for controlling pilot fuel injection in a dual fuel engine is disclosed. The control system may determine, using measurements from one or more sensors, one or more combustion parameters associated with the dual fuel engine during operation of the dual fuel engine. The control system may determine an estimated nitrogen oxides (NOx) emissions level based on the one or more combustion parameters, and may determine a NOx error based on a comparison between the estimated NOx emissions level and a desired NOx emissions level. The control system may control a quantity of pilot fuel injected into the dual fuel engine based on the NOx error.

A fuel injection system for an aircraft engine has: a first fuel injector having a first actuation inlet, a first fuel inlet connected to a fuel source, and a first fuel outlet connected to the at least one combustion chamber, the first fuel injector defining a first pressure ratio; a second fuel injector having a second actuation inlet, a second fuel inlet connected to the fuel source, and a second fuel outlet connected to the at least one combustion chamber, the second fuel injector defining a second pressure ratio; and an actuation fluid system having a circuit connected to the first actuation inlet and to the second actuation inlet, the first outlet pressure different than the second outlet pressure by having one or both of the first pressure ratio different than the second pressure ratio and a first actuation pressure different than a second actuation pressure.

An internal combustion engine in which a fuel reforming operation in a fuel reformation cylinder is not executed when a gas temperature of a fuel reformation chamber at a time point when a piston in the fuel reformation cylinder reaches a compression top dead point is estimated to fall short of a reforming operation allowable lower limit gas temperature set based on a lower limit value of a reforming reaction enabling temperature. For example, fuel is supplied from an injector so that an equivalence ratio in the fuel reformation chamber is less than 1. Alternatively, the fuel supply from an injector is stopped. This way, a supply of non-reformed fuel from the fuel reformation cylinder to an output cylinder can be avoided, and knocking in the output cylinder can be avoided.

A control device for an internal combustion engine provided with a combustion control part successively performing at least first main fuel injection and second main fuel injection and making the fuel burn by premix charged compressive ignition so as to cause generation of heat two times in stages inside the combustion chamber and cause the pressure waveform showing the change along with time of a rate of cylinder pressure rise to become a two-peak shape. The combustion control part calculates a second premix time of fuel injected by the second main fuel injection with air, reduces the injection amount of the second main fuel injection so that the second premix time becomes a first threshold value or more and performs after fuel injection after the second main fuel injection when the second premix time is less than the first threshold value, and injects the amount of fuel reduced from the injection amount of the second main fuel injection by the after fuel injection.