A fuel injection system of an internal combustion engine includes: an injector having a hydraulic control chamber controlling the delivery of fuel through the injector, an actively controlled first valve system controlling the pressure relief from the control chamber, movable between: a first position in which the first valve system closes the injector by deterring the pressure from being relieved from the control chamber through the first relief circuit, and a second position in which the first valve system opens the injector by allowing the pressure to be relieved from the control chamber through the first relief circuit. A second relief circuit allows the pressure to be relieved from the control chamber through the second relief circuit. The second relief circuit includes a second valve system passively controlled by the fuel pressure and movable between two positions deterring or allowing the pressure to be relieved from the control chamber through the second relief circuit.

A fuel injection system of an internal combustion engine includes: an injector having a hydraulic control chamber controlling the delivery of fuel through the injector, an actively controlled first valve system controlling the pressure relief from the control chamber, movable between: a first position in which the first valve system closes the injector by deterring the pressure from being relieved from the control chamber through the first relief circuit, and a second position in which the first valve system opens the injector by allowing the pressure to be relieved from the control chamber through the first relief circuit. A second relief circuit allows the pressure to be relieved from the control chamber through the second relief circuit. The second relief circuit includes a second valve system passively controlled by the fuel pressure and movable between two positions deterring or allowing the pressure to be relieved from the control chamber through the second relief circuit.

An apparatus and method for operating a fuel injector of an internal combustion engine is disclosed. A first energizing electrical current is supplied to an injector solenoid, causing the opening of an injector control volume and a pressure reduction in said injector control volume, for a first energizing time. The first energizing time is predetermined to avoid that the pressure in the injector control volume approximates a value which would cause an injector needle to raise up and a fuel injection to start. After the predetermined time interval, a second energizing electrical current is supplied to the injector solenoid for a predetermined second energizing time, which is a function of a rail pressure (p.sub.rail) and a fuel injection quantity.

A throttle device for controlling a fuel quantity to be supplied to a fuel injection nozzle includes a control chamber and a supply device for supplying fuel to the control chamber. The supply device includes an inlet throttle having a length selected such that a fuel flowing through the inlet throttle, when in operation, flows through the inlet throttle in a turbulent flow. An injection device including the throttle device is also provided.

An injector is designed to provide continuously variable injection rate shaping. With a hydro-mechanical internal feedback mechanism, injector needle position can be determined by controlling a feedback valve's on/off timing. According to the needle position, an injection needle valve opening can be controlled, and then the injection flow rate can be delivered proportionally. Also in accordance with the present invention a CRDI systems are provided including injectors of the present invention, wherein results demonstrate that injector designs of the present invention not only achieve rate shaping capability but also solve the above-noted problems of the current CRDI system. Finally, an iterative learning controller has also been developed to track the desired injection rate, and an injection rate estimator is designed to realize a cycle to cycle feedback control.

The invention relates to a fuel injection valve, comprising a nozzle body (1) and a pressure chamber (3) formed therein, wherein the pressure chamber (3) can be filled with fuel under high pressure and wherein a piston-shaped nozzle needle (5) is arranged in the pressure chamber so as to be movable longitudinally, which nozzle needle interacts with a nozzle seat (7) formed in the nozzle body (1) by means of a sealing surface (6) formed at the end of the nozzle needle on the combustion chamber side and thereby controls the flow of fuel from the pressure chamber (3) to at least one injection opening (8). A sleeve (12) accommodates the end of the nozzle needle (5) facing away from the nozzle seat and bounds a control chamber (20). By means of the pressure of the control chamber, a hydraulic force is applied to the nozzle needle (5) in the direction of the nozzle seat (7). A closing spring (16) is arranged in the control chamber (20). The closing spring is arranged between the sleeve (12) and the nozzle needle (5) under compressive preload.

A non-return valve assembly for a high-pressure fuel injection system is disclosed. The valve comprises a valve chamber defined in part by a first body and in part by a second body and defining a valve chamber wall, an inlet passage formed in the first body and opening into the valve chamber at a valve seat defined by the first body, an outlet passage, and a valve ball received within the valve chamber and engageable with the valve seat so as to interrupt fluid flow from the outlet passage to the inlet passage through the valve chamber. The valve chamber wall comprises a plurality of guide portions to guide the valve ball in substantially linear movement within the valve chamber.

A fuel injector (10) comprising a needle (16) that can move between an entirely open position (PO) and a closed position (PF) is provided with a device (82) for identifying the position of the needle, in which an electrical circuit (84) is closed in the two extreme positions (PO, PF), the needle (16) being in electrical contact with the ground (G), the circuit (84) being open in any other intermediate position (Pi) of the needle (16), the needle (16) not being grounded (G).

In a method for influencing the thread geometry of an internal thread of a first component of an injection device for internal combustion engines, which is provided for carrying high-pressure fluid, wherein the first component has a tubular end portion and an internal thread is formed on the interior surface of the tubular end portion, and a second component having an exterior surface on at least a portion thereof so as to be received in the tubular end portion of the first component wherein the exterior surface is threaded so said second component can be screwed and clamped against a support surface of the first component, and wherein the tubular end portion on the external side is acted upon by a radial compression force allowing a plastic deformation. The tubular end portion is transformed thereby in such a manner that the internal thread obtains an inner diameter (D) continuously decreasing towards the free end.

Exemplary fuel injectors for use in fuel injection devices are disclosed. An injector may have a control chamber, which can be selectively relieved of pressure by means of a pilot valve in order to control a nozzle needle stroke of an axially displaceable nozzle needle of the injector. The fuel injector may have at least one nozzle on a first end, and the control chamber on a second end of the nozzle needle. The control chamber may be sub-divided by a throttle plate accommodated therein into a first chamber and a second chamber, with the second chamber being positioned closer to the nozzle, and the two chambers communicating with each other via the throttle plate. First and second resilient elements may be accommodated in a pre-stressed manner against the throttle plate in the first chamber and in the second chamber, respectively.