The invention relates to an injection nozzle (1) for fuels, comprising a nozzle body (2), in which a pressure chamber (4) that can be filled with fuel under high pressure is formed, in which pressure chamber a piston-shaped nozzle needle (3) is arranged in such a way that the nozzle needle can be moved longitudinally. A sealing surface (6) is formed at one end of the nozzle needle (3) and an end face (9) is formed at the opposite end, wherein the sealing surface (6) interacts with a nozzle seat (5) in order to open and close at least one injection opening (8). A control chamber (10) that can be filled with fuel under changing pressure is bounded by the end face (9) of the nozzle needle (3) such that a force can be applied to the end face (9) in the direction of the nozzle seat (5) by means of the hydraulic pressure. The nozzle needle (3) has an elastic longitudinal segment (25), which has a longitudinal stiffness of less than 40,000 N/mm.

A piezo injector includes a piezo actuator arranged in an actuator chamber and a valve plunger arranged in a valve plunger bore and having a first end face facing the piezo actuator. The valve plunger is arranged between a first control chamber defined by a valve plunger bore portion delimited by the first end face and a spring chamber formed by a valve plunger bore portion opposite the first control chamber. A second control chamber is delimited by a second face of a nozzle needle and a sleeve guided by the nozzle needle. A leakage pin is arranged in a leakage pin bore between the piezo actuator and the first end face of the valve plunger. The leakage pin bore is formed in an intermediate plate arranged on a side of a control plate facing the piezo actuator, the valve plunger bore being formed in said control plate.

A fuel injector for delivering fuel to an internal combustion engine includes a nozzle having a valve needle which is movable with respect to a valve needle seat. The valve needle travels through a range of movement between a closed position and an open position to control fuel delivery through at least one nozzle outlet. The valve needle cooperates with a needle sleeve or a control member which is located in a piston guide. The valve needle is movable relative to the needle sleeve or the control member. The needle sleeve or the control member is movable relative to the piston guide.

The present invention relates to a fuel injector for use in delivering fuel to an internal combustion engine. The fuel injector includes a nozzle having a valve needle which is movable with respect to a valve needle seat. The valve needle travels through a range of movement between a closed position and an open position to control fuel delivery through at least one nozzle outlet. The valve needle cooperates with a needle sleeve or a control member which is located in a piston guide. The valve needle is movable relative to the needle sleeve or the control member. The needle sleeve or the control member is movable relative to the piston guide. The invention also relates to a method of operating a fuel injector; and a fuel injector control unit.

A valve cylinder partitions a first intermediate chamber from a second intermediate chamber. A first valve element in the first intermediate chamber includes a tubular high-pressure-side valve portion to control communication between a control chamber communication passage and the first intermediate chamber. A second valve element in the second intermediate chamber includes a low-pressure-side valve portion to control communication between an exhaust passage and the second intermediate chamber. A columnar rod portion located between the first valve element and the second valve element is slidably held at a cylinder hole of the valve cylinder. An internal passage communicates the control chamber communication passage with the second intermediate chamber. The high-pressure-side valve portion has an outer diameter greater than an outer diameter of the rod portion.

A piezo injector with an actuator chamber, in which a piezo actuator is arranged, includes an upper section (the injector body) and a lower section (the nozzle body). The piezo injector also has a control piston bore formed in the nozzle body, wherein a control sleeve, in which a control piston is received, is arranged in the control piston bore. The control sleeve seals against an intermediate plate with a first front face facing the piezo actuator. The control piston has a first side facing the piezo actuator, wherein the first front face of the control piston and the section of the control sleeve facing the piezo actuator form a first control chamber.

A sub out-orifice and an in-orifice are respectively formed in a low pressure passage and a high pressure passage of a fixed plate. A control valve is provided at an outlet port of the low pressure passage. In a normal control, the control valve starts its control-valve opening operation when a movable plate is in contact with the fixed plate. In an interval-shortening control, the control valve starts the control-valve opening operation at an earlier timing than that in the normal control, namely during a course in which a valve body is still in its valve-body closing operation.