An estimation unit estimates a fuel pressure on a discharge side of a high-pressure pump based on an amount of fuel injection with a fuel injection valve from a time point at which a detected fuel pressure changes from a higher status than a first pressure to a lower status, assuming that the fuel has not been discharged with the high-pressure pump. The determination unit determines that a relief valve is in an open status based on a dropping mode of the estimated fuel pressure and a dropping mode of the detected fuel pressure.

A characteristic determining device is provided which determines fuel injection characteristics of a plurality of fuel injectors for an internal combustion engine. The characteristic determining device includes a pressure sensor and a plurality of pipes each of which connects between the pressure sensor and one of the fuel injectors. The pressure sensor is designed to have a plurality of pressure inputs from the respective fuel injectors through the pipes and outputs a signal indicative of a level of pressure in each of the fuel injectors. The characteristic determining device analyzes the signals from the first pressure sensor to determine the fuel injection characteristics of the respective fuel injectors. These arrangements result in a simplified structure of the characteristic determining device and a decreased manufacturing cost thereof.

A fuel system is disclosed for use with an engine, including a fuel injector assembly fluidly coupled with a low-pressure fuel conduit, an accumulator, and a cap within an opening in the accumulator. The fuel injector assembly may be structured to draw in low-pressure fuel, pressurize the fuel, and store the pressurized fuel in the accumulator for injection to a combustion chamber. The cap has a pressure sensor and a pressure relief valve therein, and drains fuel leaked past fluid seals between the cap and each of the pressure sensor, the pressure relief valve, and the accumulator by way of a common drain line.

Methods and systems are provided for a ducted fuel injector. In one example, a method may include adjusting a temperature of combustion chamber gases in a combustion chamber and/or adjusting a fuel rail pressure in response to an amount of light sensed by a photodiode of the duct.

A fuel injection system for fuel metering may include an injection nozzle, which includes a nozzle body, a nozzle needle, and a nozzle orifice, wherein nozzle needle is disposed in the nozzle body; a control piston configured to mechanically and electrically contact the nozzle needle in an axial direction opposite to the nozzle orifice; a transmitter configured to communicate with a controller and electrically contact the nozzle needle via the control piston; wherein the controller is configured to determine an open state and a closed state between the nozzle needle and the nozzle body via an electrical signal detected by the transmitter; and wherein the controller is configured to adjust the open state and the closed state in correlation with a fuel injection quantity.

A fuel system for an internal combustion engine includes a common rail and a plurality of fuel injectors connected to the common rail and each including an outlet check, an injection control valve, and an injection rate controller. The injection rate controller varies a flow area to a nozzle of the fuel injector such that a pressure drop through the fuel injector is varied to provide injection rate shaping.

A fuel system for an internal combustion engine includes a common rail and a plurality of fuel injectors connected to the common rail and each including an outlet check, an injection control valve, and an injection rate controller. The injection rate controller varies a flow area to a nozzle of the fuel injector such that a pressure drop through the fuel injector is varied to provide injection rate shaping.

A system includes an injector having a scheduling valve assembly and a nozzle in fluid communication with the valve assembly. The scheduling valve assembly is configured for regulation of flow from an inlet of the injector to the nozzle. An electromagnetic device is operatively connected to a hydromechanical valve spool of the valve assembly to selectively adjust position of the valve spool in the valve assembly.

A method of determining combustion efficiency in an engine includes utilizing a control module having a computer memory, a processor, and inputs and outputs, the processor executing logic stored within the memory, sensing data by first sensors disposed on the engine and second sensors disposed in an exhaust system fluidly coupled to the engine, the first and second sensors electrically connected to the inputs, receiving within the control module data sensed by the first and the second sensors; determining an oxygen content of air entering the engine, determining an oxygen content of exhaust upstream of an oxidation catalyst; determining a fuel latent heat of vaporization; determining a fuel injection quantity to combust with oxygen entering the engine; determining a combustion efficiency index based on the oxygen content of air entering the engine and in the exhaust, and the latent heat of vaporization of fuel; and adjusting a fuel injection quantity.

A system for controlling a compression ignition engine includes: a speed obtaining section which obtains an engine speed; and an injection amount setting section which sets, in a start period after the start of cranking, a fuel injection amount to be injected by injectors in next and subsequent cycles. If an engine speed achieved by combustion in an (n1)-th cycle is higher than or equal to a determination threshold value and lower than a lower limit of the resonance range, the injection amount setting section sets the fuel injection amount for the n-th cycle to a jump-over injection amount, and sets the fuel injection amount for the (n+1)-th cycle to a resonance induction reducing amount, which is smaller than the jump-over injection amount.