In an apparatus for controlling an air/fuel ratio of a general-purpose internal combustion engine using mixed fuel containing alcohol and gasoline and operated at a desired engine speed inputted by the operator while a throttle opening is regulated such that a detected engine speed converges to the inputted desired engine speed, a fuel injection amount determined for mixed fuel based on fuel injection amount characteristics is increased/decreased when a load is kept constant and the output air/fuel ratio is estimated to correct the fuel injection amount by the estimated air/fuel ratio, while a switch (knob) is installed to be manipulated by the operator to switch the fuel injection amount characteristics.

A Dual-fuel combustion engine, possessing: a control device at least one combustion chamber at least one gas supply device for supplying a gaseous fuel to at least one combustion chamber, and at least one injector for injecting liquid fuel into the at least one combustion chamber, and which injector is controllable through a control device by the use of an actuator triggering signal, for which at least one injector possesses an output opening for the liquid fuel, which is closable by means of a needle (6), and for which the control device regulates through the use of the actuator triggering signal, the opening of the needle (6) in the ballistic region of the needle in a pilot operating mode of the combustion engine
to which end, an algorithm is stored in the control device, which receives, as input values, at least the actuator triggering signal (t) and, using an injector model, calculates the mass of liquid fuel introduced via the output opening of the injector, and which compares the mass calculated by means of the injector model with a required target value (m.sub.d.sup.ref) of the mass of liquid fuel, and on the basis of the result of such comparison, either leaves the actuator triggering signal (t) unchanged or corrects it, and a process for the operation of a combustion engine and of an injector.

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.

An estimation device applicable to a combustion system having 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 fuel used for combustion in the internal combustion engine. The combustion amount estimation unit estimates a combustion amount of fuel caused by a post combustion generated by injecting fuel into a combustion chamber of the internal combustion engine by post injection, based on the mixing ratio acquired by the mixing acquisition unit. The region estimation unit estimates a combustion region of the post combustion in the combustion chamber based on the mixing ratio. The timing estimation unit estimates an ignition timing at which ignition occurs in the combustion chamber by the post injection based on the mixing ratio.

A technique for fuel system protection for an internal combustion engine includes introducing a directly injected fuel into a combustion chamber through a direct fuel injector, introducing a fumigated fuel upstream of an intake valve, selectively operating the internal combustion engine with at least one of the directly injected fuel and the fumigated fuel, determining a temperature of the direct fuel injector as a first function of engine operating parameters, and performing a temperature mitigation technique when the temperature rises above a first predetermined value such that the temperature is maintained below a second predetermined value.

A method for controlling a dual fuel engine system includes estimating a total indicated engine load, where the total indicated engine load is based on a sum of a measured engine power and a power loss estimate. The method further includes determining a total fueling amount based on an engine speed and the total indicated engine load, where the total fueling amount includes a gas fueling amount and a diesel fueling amount. The method also includes controlling the dual fuel engine system using the total fueling amount.

A method for controlling a dual fuel engine system includes estimating a total indicated engine load, where the total indicated engine load is based on a sum of a measured engine power and a power loss estimate. The method further includes determining a total fueling amount based on an engine speed and the total indicated engine load, where the total fueling amount includes a gas fueling amount and a diesel fueling amount. The method also includes controlling the dual fuel engine system using the total fueling amount.