Provided is an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes an injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Ignition timing of the preceding ignition is set to be more retarded when an in-cylinder pressure specified by an in-cylinder pressure specification section is high than when the in-cylinder pressure is low.

The present disclosure describes an engine system that can achieve at least one of the followings: suppressing of generating of nitrogen oxides and suppressing of remaining of uncombusted hydrocarbons. The engine system has a combustion chamber to which air and a gas fuel are supplied, and is configured to combust the gas fuel. The engine system includes a liquid fuel injecting unit, and a control unit. The liquid fuel injecting unit is configured to inject a liquid fuel thereby to ignite the gas fuel. The control unit is configured to control the liquid fuel injecting unit. The control unit is configured to control the liquid fuel injecting unit so that injection of the liquid fuel is performed after a flame propagation after ignition of the gas fuel is ended.

An engine control unit of a multi-fuel is provided. The engine consumes a mixture of a first combustion fuel and a second combustion fuel. The engine control unit includes hardware circuitry that includes one or more processors configured to calculate an autoignition delay of the mixture of the air and the second combustion fuel based on current operating conditions of the multi-fuel engine. The one or more processors also are configured to calculate an upper limit on an amount of the second combustion fuel that is supplied to the multi-fuel engine based on the autoignition delay that is calculated.

An internal combustion engine is provided. The internal combustion engine includes a control device, and at least one injector for liquid fuel. The injector(s) can be controlled by the control device via an actuator control signal. The injector(s) include an injector outlet opening for the liquid fuel which can be closed by a needle. A sensor is also provided for measuring a measurement variable of the injector(s). The sensor is or can be in a signal connection with the control device. An algorithm is stored in the control device, which algorithm calculates a state of the injector(s) based on input variables and an injector model, compares the state calculated via the injector model with a target state, and produces a state signal in accordance therewith. The state signal is characteristic of a change in the state of the injector(s) that occurs during intended use of the injector(s) and/or an unforeseen change in the state of the injector(s). The input variables include at least the actuator control signal and the measurement values of the sensor. A method for operating such an internal combustion engine and an injector is also provided.

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.

The engine control method includes a fuel supply step and an ignition step. In the fuel supply step, the injector supplies fuel into a combustion chamber. In the ignition step, an spark plug arranged in the combustion chamber makes a flame after the supply of the fuel into the combustion chamber and at a timing when a flow strength in the combustion chamber is greater than a predetermined value in a compression stroke during or before a post-mid stage where the compression stroke is divided into four stages of a pre-stage, a pre-mid stage, a post-mid stage, and a post-stage.

Control is performed so as to occur SPCCI combustion in which, after an air-fuel mixture in a first area of a combustion chamber that includes an electrode portion of an ignition device is burned by receiving ignition energy, an air-fuel mixture formed in a second area located on an outer periphery of the first area is self-ignited. Control is also performed such that, in a high load operation region of an SPCCI combustion execution region, an air-fuel ratio in the entire combustion chamber becomes richer than a stoichiometric air-fuel ratio and that an air-fuel ratio of the air-fuel mixture in the first area becomes leaner than an air-fuel ratio of the air-fuel mixture in the second area.

An engine control apparatus includes an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate the SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes the injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Energy of the preceding ignition is set to be higher when an engine speed is high than when the engine speed is low.

When an incremental amount of a steering angle exceeds a reference incremental amount, an ECU 60 executes vehicle attitude control of reducing an output torque of an engine, and, in a given operating range, drives a spark plug 16 to allow an air-fuel mixture to be self-ignited at a given timing, thereby executing SPCCI combustion. When there is a request for an additional deceleration from the vehicle attitude control (#12: YES) and the SPCCI combustion is performed (#13: YES), the ECU 60 prohibits ignition retardation and performs torque reduction for the vehicle attitude control, by fuel amount reduction control of reducing the amount of fuel to be supplied into a cylinder 2 (#14). On the other hand, when the SPCCI combustion is not performed (NO in #13), the ECU 60 performs the ignition retardation to attain the torque reduction for the vehicle attitude control (#15).

When an incremental amount of a steering angle exceeds a reference incremental amount, an ECU 60 executes vehicle attitude control of reducing an output torque of an engine, and, in a given operating range, drives a spark plug 16 in a manner allowing an air-fuel mixture to be self-ignited at a given timing, thereby executing SPCCI combustion. When there is a request for an additional deceleration from the vehicle attitude control (#12: YES), and the SPCCI combustion is performed (#13: YES), the ECU 60 executes fuel amount reduction control of reducing the amount of fuel to be supplied into a cylinder 2 (#14), so as to attain torque reduction for the vehicle attitude control. On the other hand, when the SPCCI combustion is not performed (#13: NO), the ECU 60 executes ignition retardation control of retarding an ignition timing of the spark plug 16 (#15).