A fuel injector includes a housing defining a longitudinal bore having a proximal end and a distal end, a high pressure fuel duct in communication with the longitudinal bore and a valve seat including a valve seat surface and an aperture at the distal end of the longitudinal bore. A poppet valve is disposed in the longitudinal bore and includes a valve head that is engageable with the valve seat surface. An actuator device is disposed at the proximal end of the longitudinal bore and a hydraulic coupler is disposed between the actuator and the poppet valve within the longitudinal bore. The hydraulic coupler defines a chamber that receives low pressure fuel for providing a hydraulic lash adjuster between the actuator and the poppet valve.

The present disclosure relates to internal combustion engines. The teachings thereof may be embodied in injection valves with servo-valve control for injecting fuel into the combustion chamber. For example, an injection valve may include a valve pin connected to a valve body and an actuator preloaded by an actuator spring. The valve pin is fitted with a very small clearance to form a sealing gap between the valve pin and the valve body which includes bores. The lower end of the valve pin forms a coupling volume between the valve pin and the valve body, connected via the sealing gap and the bores to the valve chamber. The sealing gap provides a fluidic connection between the coupling volume and the valve chamber, but, during the short time of valve actuation, practically no exchange of fluid can take place between coupling volume and valve chamber so that the coupling volume does not substantially change in said short time.

The present disclosure relates to internal combustion engines. The teachings thereof may be embodied in injection valves with servo-valve control for injecting fuel into the combustion chamber. For example, an injection valve may include a valve pin connected to a valve body and an actuator preloaded by an actuator spring. The valve pin is fitted with a very small clearance to form a sealing gap between the valve pin and the valve body which includes bores. The lower end of the valve pin forms a coupling volume between the valve pin and the valve body, connected via the sealing gap and the bores to the valve chamber. The sealing gap provides a fluidic connection between the coupling volume and the valve chamber, but, during the short time of valve actuation, practically no exchange of fluid can take place between coupling volume and valve chamber so that the coupling volume does not substantially change in said short time.

An injector includes an actuator arranged in an actuator space, a piston guide having a bore hole, and a piston arranged in the bore hole. The piston has a first end face facing the actuator and delimiting a first space in and/or on the bore hole, and a second end face lying opposite the first space and delimiting an adjoining second space in and/or on the bore hole. The piston is arranged between the first and second spaces, and a gap extends around the circumference of the piston between the piston and the bore hole. The piston includes a first material and the piston guide includes a second material, the first and second materials having different thermal expansion properties such that when the piston guide and/or piston are heated, the gap width of the gap decreases to limit fuel leakage between the first space and second spaces.

A fuel injector includes a housing defining a longitudinal bore having a proximal end and a distal end, a high pressure fuel duct in communication with the longitudinal bore and a valve seat including a valve seat surface and an aperture at the distal end of the longitudinal bore. A poppet valve is disposed in the longitudinal bore and includes a valve head that is engageable with the valve seat surface. An actuator device is disposed at the proximal end of the longitudinal bore and a hydraulic coupler is disposed between the actuator and the poppet valve within the longitudinal bore. The hydraulic coupler defines a chamber that receives low pressure fuel for providing a hydraulic lash adjuster between the actuator and the poppet valve.

A fuel electro-injector for a fuel injection system for an internal combustion engine, having an atomizer equipped with a nozzle and a valve needle defining a discharge section that is annular and has a width that continuously increases as the opening stroke of the valve needle proceeds. The opening stroke is directed outwards and is caused, in a proportional manner, by the operation of an electric actuator. The electro-injector has a high-pressure environment with an annular passageway around the lateral outer surface of the valve needle to supply fuel to the discharge section, and a low-pressure environment, which communicates with a fuel outlet and is separated from the high-pressure environment by a dynamic seal between the valve needle and the nozzle. The electro-injector is provided with a hydraulic connection between the electric actuator and the valve needle, with a pressure chamber axially delimited, on one side, by the valve needle and, in use, is filled with fuel that, once compressed, axially pushes the valve needle along the opening stroke. The hydraulic connection is placed in the low-pressure environment, so that the pressure chamber only communicates with this environment.

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 hydraulic coupling is specified, particularly for fuel injectors, which has a housing pot having a pot bottom and a lateral pot surface, a piston guided axially displaceably in the housing pot, a fluid-filled coupling gap that is provided between the piston and the pot bottom, diaphragm situated on the outer side of the housing pot facing away from the piston, a compensation chamber that is bordered by the diaphragm and flow-connected to the coupling gap, and a spring element acting upon the diaphragm with an axially directed spring force. In order to achieve a low overall stiffness of the hydraulic coupling at the required specified coupling force, the spring element is developed as a spring bracket fixed to the housing pot, which lies against the diaphragm with axial prestressing in the region of the pot bottom.