Methods and systems are provided for an engine to infer fuel temperature from a measured rate of change in a pressure of a fuel passage between a low pressure fuel pump and a high pressure fuel pump during certain operating conditions, including when the low pressure fuel pump is switched off. The operation of the low pressure fuel pump may be adjusted responsively to a change in the inferred fuel temperature.

Methods and systems are provided for an engine to infer fuel temperature from a measured rate of change in a pressure of a fuel passage between a low pressure fuel pump and a high pressure fuel pump during certain operating conditions, including when the low pressure fuel pump is switched off. The operation of the low pressure fuel pump may be adjusted responsively to a change in the inferred fuel temperature.

An assembly at least comprising a fuel injector for dual fuel operation of an internal combustion engine. The assembly includes a nozzle holder defining a fuel circuit and provided with a nose adapted in use to be in connection with a combustion space of an internal combustion engine, and first and second nozzles in communication with the fuel circuit in the nozzle holder for directly injecting liquid fuel into the combustion space of the internal combustion engine for ignition of a combustible mixture present in the combustion space. The first and second nozzles adjacent to the nose of the nozzle holder are interconnected by a cooling channel. At each actuation of a fuel pump upstream of the first and second nozzles, substantially a full volume of fuel pumped during actuation of the fuel pump is allowed to flow through the cooling channel and via the first and second nozzles.

A method for operating a combustion engine is provided. A fuel injector is operated to perform a fuel injection, a sequence of pressure signals of the fuel rail pressure during the fuel injection is sampled and filtered and a total pressure difference between a first sample after a top dead center of the fuel pump and before the fuel injection has started and a chosen second sample after the injection and before a next pumping stroke is determined. A linear pressure slope at the second sample and a leakage pressure difference between the first sample and the second sample based on the linear pressure slope is calculated, leading to calculating an injection pressure difference as the difference between total pressure difference and the leakage pressure difference. With this, a value of a fuel quantity injected as a function of the injection pressure difference can be determined, while leakages are compensated.

Fuel injection control systems and methods for enhancing the delivery of low quantities of fuel in internal combustion engines. Calibration/control data may be continuously generated and updated during the operation of the engine, for example without delivering fuel to the engine cylinders. Disclosed embodiments include periodically operating one or more fuel injectors of the engine in a non-injection state; generating and storing parameter information representative of the operation of the one or more fuel injectors in the non-injection state; and operating the one or more fuel injectors in an injection state to inject a desired pulse of fuel based upon the parameter information and information representative of an additional amount of fuel.

A method for operating an internal combustion engine having a number of cylinders and an injection system having an injection system that has a common rail and a number of injectors associated with the cylinders, wherein an individual accumulator is associated with each injector and stores fuel from the common rail for the injector. The method has the following steps: starting the internal combustion engine, operating the internal combustion engine, shutting off the internal combustion engine. The following steps are also provided: a state indicating an engine standstill is detected, in particular after the internal combustion engine has been shut off, a high-pressure limit value is defined and a target high pressure is specified, a leakage is produced in the common rail without injection, the fuel pressure in the common rail is reduced to the defined high-pressure limit value below the target high pressure by way of the leakage.

A fuel injector for a combustion engine is disclosed. The fuel injector includes an injector body having a nozzle orifice, a solenoid coil mounted in the injector body, a control chamber filled with high-pressure fuel, an armature moved by electromagnetic force of the solenoid coil to vary fuel pressure in the control chamber, and a needle that moves to open or close the nozzle orifice according to the variation in the fuel pressure in the control chamber. The fuel injector further includes piezoelectric actuator for adjusting a fuel injection rate by adjusting an opening speed of the nozzle orifice based on a load condition of the engine.

An engine control system is structured for operating a turbocharged engine system and includes an electronic control unit. The electronic control unit is structured to switch the engine system from operation in a parasitically loaded mode where fuel pressurized by a fuel pump is dumped to a low pressure space, to operation in a second mode, where an engine load increase is detected. Turbocharger lag in the engine system is limited during increasing the engine load by way of exhaust energy produced in response to the parasitic loading. Related methodology is disclosed.

A method and apparatus are disclosed for determining the fuel quantity that is actually injected by a fuel injector in an internal combustion engine. A fuel injector is operated to perform a fuel injection. The first discharge stroke of the fuel pump is deactivated following a start of the fuel injection for preventing the discharge stroke from delivering fuel into the fuel rail. A value of a pressure drop caused into the fuel rail by the fuel injection is calculated. A value of a fuel quantity injected by the fuel injection is calculated on the basis of the calculated value of the pressure drop.

The pressure of the fuel is increased at a constant pressure intensification ratio after operating the pressure reducing device so that the pressure difference between the fuel passage and the control chamber after the operation has a value smaller than the predetermined pressure difference, if the required pressure of the fuel is higher than a reference pressure and lower than a pressure obtained by multiplying the reference pressure by a constant pressure intensification ratio.