Disclosed is a method for determining a static flow rate of a piezo-electric injector of an injection system. The piezo-electric injector includes a needle and a piezo-electric actuator designed to control a valve of the injector. The injection system includes an electric generator designed to send electric current pulses to the piezo-electric actuator of the injector, and a voltage sensor designed to measure voltage values at the terminals of the piezo-electric actuator. The method includes the following steps: sending during a phase of closure of the needle of an electric current pulse such that the piezo-electric actuator is positioned in contact with the valve, without giving rise to the opening thereof; measurement of a plurality of voltage values of the piezo-electric actuator; and determining a static flow rate of the piezo-electric injector on the basis of a plurality of voltage values measured of the piezo-electric actuator.

The invention relates to a method for operating a fuel injector (10) and to a fuel injector (10) which is configured to carry out the method. The method comprises the steps of introducing a fuel under high pressure into a feed passage (78) and branching off a substream of the fuel under high pressure into a control space (74) in which an axial end face (70) of the nozzle needle (50) is loaded with the pressure such that the nozzle needle (50) is hydraulically loaded in the closing direction, and of opening a control valve (90) such that an outflow path arranged downstream of the control valve (90) in an outflow direction is freed and fuel flows out of the control space (74) in order to relieve the nozzle needle (50), wherein the fuel flowing out via the outflow path is divided into at least two substreams.

A method according to the invention for checking the plausibility of the function of a pressure sensor in an injection system of an internal combustion engine includes acquiring a calibrated actuation profile, by which peak current values for opening at least one electrically actuatable injection valve are assigned to existing internal pressures. An existing internal pressure is measured in the form of an actual sensor pressure value by the pressure sensor. The method includes obtaining the electrical peak current value corresponding to the measured sensor pressure value from a calibrated actuation profile, such that the corresponding electrical peak current value acquired in this way is applied to the injection valve. Subsequently, an opening state of the injection valve is monitored in reaction to the applied electrical peak current value, and a functional state of the pressure sensor is assigned as a function of the opening state of the injection valve.

A vehicle fuel injector is configured to inject a high-pressure vehicle fuel received from a fuel rail into a combustion chamber. The vehicle fuel injector includes a nozzle which includes a plurality of discharge flow paths which are disposed to be spaced apart from each other in a circumferential direction and pass through the nozzle in a longitudinal direction, and outward flow paths formed on an inner circumferential surface of the nozzle, the nozzle having a hollow shape, and a needle bar which is formed to pass through the inner circumferential surface of the nozzle and vertically reciprocally moves on the inner circumferential surface of the nozzle, where rotation of the needle bar is adjusted in a left or right direction so that the nozzle is opened or closed.

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 vehicle fuel injector is configured to inject a high-pressure vehicle fuel received from a fuel rail into a combustion chamber. The vehicle fuel injector includes a nozzle which includes a plurality of discharge flow paths which are disposed to be spaced apart from each other in a circumferential direction and pass through the nozzle in a longitudinal direction, and outward flow paths formed on an inner circumferential surface of the nozzle, the nozzle having a hollow shape, and a needle bar which is formed to pass through the inner circumferential surface of the nozzle and vertically reciprocally moves on the inner circumferential surface of the nozzle, where rotation of the needle bar is adjusted in a left or right direction so that the nozzle is opened or closed.

The pressing part includes an abutment part capable of being in contact with the inner peripheral surface of the pressing passage, and a depressed opposite part that is opposed to the exhaust port at a position away from the exhaust port in a perpendicular direction perpendicular to the displacement direction due to an outer peripheral surface of the pressing part recessed from the abutment part even when the abutment part is in contact with the inner peripheral surface of the pressing passage. When the abutment part is in contact with the inner peripheral surface of the pressing passage, a depression dimension of the depressed opposite part relative to the abutment part is set, such that an amount of fuel discharged from the valve chest is defined by the exhaust throttle part instead of a gap between the depressed opposite part and the inner peripheral surface of the pressing passage.

A fuel injection device has a valve body, a drive portion, a nozzle needle, and a control valve body. The valve body defines a control chamber, a valve chamber and a low pressure communication passage. The nozzle needle is displaced due to a fuel pressure variation in the control chamber to open/close an injection port. When the control valve body sits on an upper seat surface, a low pressure communication passage is closed so that the valve chamber is fluidly disconnected from the low pressure chamber. The control valve body defines a gap restriction on the upper seat surface. A flow passage area of a sub orifice provided to the low pressure communication passage is smaller than a flow passage area of the gap restriction.

A method for monitoring an injector for common-rail injection systems includes detecting an electrical signal indicative of a deformation of a diaphragm of a head plate having a reaction surface facing a control chamber of the injector and processing the deformation signal to determine characteristic data of the operation of the injector.

A control valve arrangement includes a valve body with a filling chamber with a filling hole. A filling valve is arranged in the filling chamber for opening or closing a first fluid communication controlling filling of a first control chamber, the filling valve having a filling valve member with a moving valve seat, the filling valve member being normally biased open by a first spring. A control valve opens and closes a second fluid communication for controlling the emptying of the first control chamber, the control valve being normally biased closed by a second spring. A plug is arranged in the valve body for closing the filling chamber, the plug being provided with an opening which cooperates with the moving valve seat, the opening defining the first fluid communication between the filling chamber and the first control chamber.