An estimation device that is applicable to a combustion system including an internal combustion engine includes a mixing acquisition unit, a combustion amount estimation unit, a region estimation unit, and a timing estimation unit. The mixing acquisition unit acquires a mixing ratio of various components contained in the fuel used for combustion in the internal combustion engine. The combustion amount estimation unit estimates a combustion amount of the fuel caused by a pilot combustion produced by injecting the fuel into a combustion chamber of the internal combustion engine with a pilot injection, based on the mixing ratio acquired by the mixing acquisition unit. The region estimation unit estimates a combustion region of the pilot combustion in the combustion chamber based on the mixing ratio. The timing estimation unit estimates an ignition timing, at which an ignition occurs in the combustion chamber with the pilot injection, based on the mixing ratio.

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 apparatus for a compression autoignition engine controls compression autoignition by ignition. The control apparatus includes an injector, a spark plug, and a controller. The controller controls the injector so that fuel is injected by a plurality of divided injections, and thereafter, outputs a control signal to the spark plug at predetermined ignition timing so that, by ignition, unburned air-fuel mixture combusts by autoignition. Control is performed so that, when load on the engine is high, an amount of fuel injected at later timing among the plurality of injections becomes larger than when the load is low.

An engine breather filter assembly for monitoring an internal combustion comprises: a filter cavity configured to accommodate a breather filter element; a processor; and a sensor module configured to sense a characteristic of the internal combustion engine and output data representative of the sensed characteristic to the processor. The engine breather filter assembly is configured to provide a housing for the processor. The processor is configured to determine a value representative of the firing frequency of the internal combustion engine based on the output data.

A control apparatus for a compression autoignition engine controls compression autoignition by ignition. The control apparatus includes an injector, a spark plug, and a controller. The controller controls the injector so that fuel is injected by a plurality of divided injections, and thereafter, outputs a control signal to the spark plug at predetermined ignition timing so that, by ignition, unburned air-fuel mixture combusts by autoignition. Control is performed so that, when load on the engine is high, an amount of fuel injected at later timing among the plurality of injections becomes larger than when the load is low.

A method for operating a spark ignited engine, including forming a combustible mixture by mixing generally homogeneously a first fuel and air and introducing this mixture into the at least one cylinder in an intake stroke, and compressing the combustible mixture with a piston in a compression stroke thereby introducing a part of the combustible mixture into a pre-chamber. During the intake and/or the compression stroke, a second fuel is introduced into the pre-chamber at an introduction-time before start of combustion, and the second fuel is of the same or different chemical composition and/or concentration with respect to the first fuel, and a spark ignites in the prechamber. An amount of second fuel and/or the chemical composition of second fuel introduced to the pre-chamber and/or spark timing of the pre-chamber and/or an in-cylinder charge temperature is chosen such that a desired duration of combustion can be achieved.

A control apparatus for an engine includes an engine, a state quantity setting device, an injector, a spark plug, and a controller. The controller sets a G/F in a range from 18 to 50. After the spark plug ignites air-fuel mixture, unburned air-fuel mixture is combusted by autoignition.

A control device for an internal combustion engine includes an electronic control unit. The electronic control unit is configured to control an injection amount and an injection timing of fuel to a target injection amount and a target injection timing set based on an engine operation state, detect an ignition timing of fuel based on a vibration component of an engine body in a specific frequency bandwidth, and correct at least one of the target injection amount and the target injection timing based on a deviation between the detected ignition timing and a target ignition timing according to the engine operation state. The specific frequency bandwidth is a bandwidth on a low frequency side of a frequency bandwidth where the engine body undergoes elastic vibration.

According to one or more embodiments, an internal combustion engine may be operated by a method which includes one or more of injecting a first fuel and a second fuel into an engine cylinder to form a fuel mixture, and combusting the fuel mixture with a spark plug to translate a piston housed in the engine cylinder and rotate a crank shaft coupled to the piston. The first fuel may comprise a greater octane rating than the second fuel. A target CA50 may correspond to a minimum in specific fuel consumption of the fuel mixture. The spark plug may initiate combustion at a time such that the internal combustion engine operates with an operational CA50 that is within 20 degrees of the target CA50.

Based on respective signals from the combustion pressure sensor and a crank angle sensor, heat generation amount data in which a heat generation amount and a crank angle are related to each other is generated, and an estimated heat generation amount is calculated based on a fuel amount in the combustion cycle. When a final value of a heat generation amount in the combustion cycle is smaller than the estimated heat generation amount, the combustion state parameter is calculated based on the heat generation amount data to a crank angle corresponding to the final value of the heat generation amount. When the final value of the heat generation amount is equal to or larger than the estimated heat generation amount, the combustion state parameter is calculated based on the heat generation amount data to a crank angle at which the heat generation amount reaches the estimated heat generation amount.