A method is disclosed of controlling operation of a fuel injector in response to measuring a quantity of fuel injected by the fuel injector from a fuel accumulator to an engine cylinder during operation of a fuel pump that delivers fuel to the accumulator, comprising: determining an average pressure of the fuel accumulator during a first time period before a fuel injection event; predicting a mass of fuel delivered to the fuel accumulator during a pumping event (Q.sub.pump); determining an average pressure of the fuel accumulator during a second time period after the fuel injection event; estimating a leakage of fuel; computing the injected fuel quantity by adding the average pressure during the first time period to Q.sub.pump, and subtracting the average pressure during the second time period and the leakage; and using the computed injected fuel quantity to control operation of the fuel injector.

An engine control apparatus is equipped with a fuel injection amount computation unit, a determination process unit, and an engine abnormality process unit. The determination process unit determines, based on a deviation between a command injection amount and a monitoring injection amount, whether or not there is an abnormality in fuel injection control. An injection amount threshold, which is used to make a determination on an abnormality in fuel injection control, is set larger based on a vehicle speed-associated parameter when the vehicle speed-associated parameter is a value corresponding to a case where a vehicle speed is high than when the vehicle speed-associated parameter is a value corresponding to a case where the vehicle speed is low.

An injection control device includes: an area correction unit that calculates an energization time correction amount when executing a current drive of the fuel injection valve to inject a fuel from the fuel injection valve; an estimation unit that independently calculates an estimated energization time correction amount; a comparison unit that compares the energization time correction amount c with the estimated energization time correction amount; and a first abnormality determination unit that determines that the energization time correction amount is abnormal.

A method for operating an internal combustion engine having at least one fuel injector that is activated for opening and closing via a solenoid valve of a respective fuel injector. Commencing with the activation of the fuel injector for opening, structure-borne sound waves emitted by the fuel injector over the time are detected by measurement. A structure-borne sound wave signal detected by measurement over the time is evaluated such that dependent on the amount of at least one maximum of the structure-borne sound wave signal and/or dependent on the number of the maximums of the structure-borne sound wave signal and/or in the presence of multiple maximums dependent on the time sequence and/or on the amount of the maximums, an operating state of the respective fuel injector is deduced.

In some embodiments, a method includes: setting an actuation time based on a predefined injection quantity; detecting a duration of a resulting closing process; calculating an injection quantity based on the time and the duration; determining the difference of the injection quantity and the predefined quantity; and determining a corrected value of the actuation time based on the difference; and using the corrected value to control further actuation of the fuel injector. The injection quantities and the actuation time are on a characteristic diagram of the relationship between the actuation time, the duration of the closing process, and the injection quantity.

A method and a device for determining the injection quantity or the injection rate of a fluid which is transported to an injector through a hydraulic line and is injected into a reaction space by the injector. The fluid pressure in the hydraulic line is measured by a pressure sensor, the fluid pressure at the injector is determined using the pressure measured by the pressure sensor and a stored transmission function of the hydraulic line, and the injection quantity or the injection rate of the fluid injected by the injector is determined using the fluid pressure determined at the injector.

A method for operating an internal combustion engine having a common-rail injection system as a function of a quantity of fuel injected. The method includes determining an information item about a relative-pressure characteristic from a characteristic of an absolute rail pressure in a high-pressure reservoir of the common-rail injection system; determining the quantity of fuel injected as a function of the information item about the relative-pressure characteristic, and with the aid of a trained functional model, in particular, a nonparametric functional model or a neural network; operating the internal combustion engine as a function of the quantity of fuel injected.

A method for controlling the total injection mass per working cycle during a multiple injection operation of a fuel injector of an internal combustion engine is provided. In the method, an injection mass difference is determined from individual injection pulse to individual injection pulse, and transferred to the next individual injection pulse, in stepwise fashion. The injection mass difference remaining in the penultimate individual injection pulse is transferred to the final individual injection pulse to achieve a total injection mass with improved tolerance.

A method for determining a quantity of fuel injected into a cylinder of an internal combustion engine including an injection rail includes:—measuring the pressure prevailing in the injection rail during fuel injection from the rail into a cylinder;—filtering the pressure measurement;—determining the relative minimum and maximum points of the filtered pressure curve;—insofar as a first (Pdrop1) pressure drop followed by a pressure rise and then a second (Pdrop2) pressure drop is identified, determining a physical quantity that makes it possible to characterize the first pressure drop and the second pressure drop; and—determining the quantity of fuel injected by applying the bulk modulus for the two pressure drops identified as a function of the temperature in the injection rail.

The present disclosure provides a method for learning emergency injection correction of an injector for preventing misfire. A misfire rate in a multi-stage injection mode is monitored, and it is controlled to be forcibly switched to a single injection mode when the misfire rate by the monitoring is equal to or greater than a specific value, such that injector injection correction learning is performed according to a learning entry condition. Accordingly, it is possible to reduce the deviation between cylinders by the sufficient injection amount deviation correction learning, thereby preventing misfire of the injector.