A fuel injector includes an injector body comprising an internal injector cavity, a flow passageway, and a drain conduit. The flow passageway is in fluid communication with at least one injector orifice. The fuel injector further includes a valve assembly comprising a valve seat and a valve member in fluid communication with the fuel circuit. The valve member is configured to move between an open position allowing fuel flow through the at least one injector orifice and a closed position inhibiting fuel flow through the at least one injector orifice. The fuel injector also includes a nozzle valve element fluidly coupled to the valve assembly, an actuator operably coupled to the valve assembly and the nozzle valve element, and a flexible member configured to elastically deform in response to pressure in the fuel injector. The flexible member is configured to inhibit flow to the drain circuit during an injection event.

Various embodiments may include a method for operating a diesel-common-rail piezo-operated servo injector comprising: partially charging the piezo-actuator from a non-charged state at 0 V (method a); partially discharging the piezo-actuator from an already charged state to a remaining limited charge (method b); measuring the piezo-voltage with both methods and comparing the results; when the comparison demonstrates correspondence within a predefined threshold, using method b in ranges in which method a cannot be carried out; and when the comparison does not demonstrate correspondence within the predefined threshold, using method a without using method b.

The teachings of the present disclosure describe an injector having an injector housing, an actuator, and a nozzle needle, wherein the actuator is arranged in an actuator space of the injector housing. The injector may include a control piston bore in the injector housing, in which a control piston is arranged, a leakage pin bore between the actuator space and the control piston bore, and a leakage pin coupling the control piston to the actuator, the leakage pin arranged in the leakage pin bore. The control piston may be hydraulically connected to the nozzle needle in order to open or close an outlet opening of the injector housing. The injector may include a high pressure line configured to convey a fuel under pressure to the nozzle needle and a feedline in the injector housing connecting the leakage pin bore to the high pressure line.

A fuel injection control device includes an electric controller controlling an opening and closing of an injector by energizing a coil in the injector, and a booster circuit boosting a battery voltage to generate a boost voltage. The electric controller includes a valve-opening control unit applying the boost voltage and then applying the battery voltage to the coil to execute a valve-opening control to generate a required valve-opening force, an open valve maintenance control unit applying the battery voltage to the coil to execute an open valve maintenance control to generate an open valve maintenance force and is smaller the required valve-opening force, after the valve-opening control, and a current correction control unit executing a current correction control to correct a maximum value of a current flowing through the coil when the boost voltage is applied in the valve-opening control, according to a decreasing quantity of the battery voltage.

The invention relates to a method and a device for actuating an injection valve, which has a piezo actuator and a nozzle needle, of a fuel injection system of an internal combustion engine, in which method a control unit, in a manner dependent on a setpoint stroke height of the piezo actuator in successive injection cycles, outputs a control signal for changing the actual stroke height of the piezo actuator, characterized in that the control unit changes the setpoint stroke height of the piezo actuator, for compensation of the temperature dependency of the capacitance of the piezo actuator, in a manner dependent on the temperature of said piezo actuator.

A fuel injector for injecting fuel vapour into a combustion chamber of an internal combustion engine. The injector has a central axis and is mountable to the internal combustion engine so that the fuel injector projects into the combustion chamber. The injector has an inlet for supplying fuel to the fuel injector. The inlet projects from the injector body at a first circumferential position of the injector body. The inlet has a component of projection, X, radially outward relative to the central axis of the injector. The injector also has a spray nozzle having a tip and the spray nozzle extends longitudinally from the injector body. The injector has a plurality of spray discharge orifices formed on the tip with an even radial distribution about the tip. Each spray discharge orifice is configured to discharge fuel vapour. Each spray discharge orifice has a component of direction parallel to the central axis and a component of direction, Y, radially outward relative to the central axis. Y is at an angle offset from X.

A fuel injector, preferably a dual fuel injector, for an internal combustion engine is disclosed. The fuel injector comprises first and second valve needles (80, 100) arranged to control the injection of first and second fuels, first and second control chambers (88, 10) associated with the first and second valve needles (80, 100) respectively, a first control valve (26) comprising a first control valve member (48) and arranged to vary the pressure of a control fluid in the first control chamber (88) so as to cause opening and closing movement of the first valve needle (80), and a second control valve (28) comprising a second control valve member (60) and arranged to vary the control fluid 10 pressure in the second control chamber (110) so as to cause opening and closing movement of the second valve needle (100). The first and second control valve members (48, 60) are arranged for linear movement along a common control valve axis.

Various embodiments may include a method for operating a diesel-common-rail piezo-operated servo injector comprising: partially charging the piezo-actuator from a non-charged state at 0 V (method a); partially discharging the piezo-actuator from an already charged state to a remaining limited charge (method b); measuring the piezo-voltage with both methods and comparing the results; when the comparison demonstrates correspondence within a predefined threshold, using method b in ranges in which method a cannot be carried out; and when the comparison does not demonstrate correspondence within the predefined threshold, using method a without using method b.

A fuel injection device is provided with a valve body, a nozzle needle, a movable plate, and a support spring. The valve body has a control chamber therein. The control chamber is defined by a defining wall which has a dividing wall portion. The dividing wall portion divides the control chamber into an accommodation chamber and a backpressure chamber. The accommodation chamber accommodates a movable plate and a support spring. A fuel pressure in the backpressure chamber is applied to the nozzle needle. The dividing wall portion has a restriction hole fluidly connecting the accommodation chamber and the backpressure chamber with each other, and a support surface supporting the support spring.

A fuel injection control device includes an electric controller controlling an opening and closing of an injector by energizing a coil in the injector, and a booster circuit boosting a battery voltage to generate a boost voltage. The electric controller includes a valve-opening control unit applying the boost voltage and then applying the battery voltage to the coil to execute a valve-opening control to generate a required valve-opening force, an open valve maintenance control unit applying the battery voltage to the coil to execute an open valve maintenance control to generate an open valve maintenance force and is smaller the required valve-opening force, after the valve-opening control, and a current correction control unit executing a current correction control to correct a maximum value of a current flowing through the coil when the boost voltage is applied in the valve-opening control, according to a decreasing quantity of the battery voltage.