A fuel injector device for injecting fuel into a combustion chamber of an internal combustion engine is provided. Included in the fuel injector is a body having a chamber and a pilot valve assembly including a seat retainer configured to be detachably insertable into the chamber of the body. A pilot valve seat is disposed in the seat retainer and substantially enclosed by the seat retainer. A stator assembly is disposed in the seat retainer and at least partially enclosed by the seat retainer. The pilot valve seat and the stator assembly in the pilot valve assembly are replaceable as a single unit of the pilot valve assembly for the fuel injector.

A fuel injection device injecting a fuel from an injection hole to a combustion chamber of an internal combustion engine includes a valve body including a fuel passage through which the fuel flows to the injection hole and a seat portion facing the fuel passage, a valve member moving in the valve body in an axial direction of the valve body and opening and closing the injection hole by being removed from and seated on the seat portion, a dividing member defining a pressure control chamber placed at a position opposite to the injection hole with respect to the valve member, and an outer peripheral member surrounding an exterior of an outer periphery of the dividing member. The pressure control chamber controls a movement of the valve member by a pressure of the fuel that is introduced. The outer peripheral member and the valve body constitute the fuel passage.

A fuel injector device for injecting fuel into a combustion chamber of an internal combustion engine is provided. Included in the fuel injector is a body having a chamber and a pilot valve assembly including a seat retainer configured to be detachably insertable into the chamber of the body. A pilot valve seat is disposed in the seat retainer and substantially enclosed by the seat retainer. A stator assembly is disposed in the seat retainer and at least partially enclosed by the seat retainer. The pilot valve seat and the stator assembly in the pilot valve assembly are replaceable as a single unit of the pilot valve assembly for the fuel injector.

A fuel injection device injecting a fuel from an injection hole to a combustion chamber of an internal combustion engine includes a valve body including a fuel passage through which the fuel flows to the injection hole and a seat portion facing the fuel passage, a valve member moving in the valve body in an axial direction of the valve body and opening and closing the injection hole by being removed from and seated on the seat portion, a dividing member defining a pressure control chamber placed at a position opposite to the injection hole with respect to the valve member, and an outer peripheral member surrounding an exterior of an outer periphery of the dividing member. The pressure control chamber controls a movement of the valve member by a pressure of the fuel that is introduced. The outer peripheral member and the valve body constitute the fuel passage.

The present disclosure relates to internal combustion engines. Various embodiments thereof may include a piezo injector for fuel injection. For example, an injector may include: a nozzle unit with a nozzle needle; a piezoelectric actuator unit; and a hydraulic coupler unit coupling the nozzle unit to the actuator unit. The coupler unit includes a coupler piston, a coupler cylinder, and a coupler spring. The coupler piston has a top side facing toward the coupler cylinder and a bottom side. The coupler spring pushes the coupler piston against a face side of the nozzle needle oriented toward the bottom side of the coupler piston and has a contact area with the nozzle needle. The coupler piston includes a passage opening providing a flow connection from the bottom side of the coupler piston to the top side of the coupler piston, arranged within the contact area.

A piezo injector for direct fuel injection may comprise an injector body, an actuator unit having a piezoelectric actuator with a head plate and a base plate, a hydraulic coupler having a coupler piston, a coupler cylinder, and a coupler spring, and a nozzle unit having a nozzle needle arranged in a nozzle body. The piezoelectric actuator is surrounded by a corrugated tube braced between the head plate and the base plate such that the piezoelectric actuator has a preload imparted to it. The coupler spring forces the coupler piston against a face side, facing toward the coupler piston, of the nozzle needle.

A fluid injector has a solid state actuator and a control piston unit arranged in a recess of an injector body. A transmission pin mechanically couples the actuator to the control piston unit. A first control chamber, coupled hydraulically to a second control chamber, is delimited by the control piston unit and the injector body. A control piston of the control piston unit has an end surface that is coupled to the transmission pin and which delimits the first control chamber. The control piston unit has a control sleeve arranged coaxially with the control piston and an inwardly directed projection that provides a driving coupling between the control piston and the control sleeve after a predefined control stroke of the control piston. The driving coupling results in the control piston influencing a free volume of the first control chamber during an axial movement of the control piston.

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.