Abstract: A mobile valve member designed to be arranged in the nozzle body of a fuel injector, extends along a main axis and includes a piston formed of a first male cylinder of effective diameter forming the top end of the mobile member and of a second cylinder provided with an internal cylindrical bore of the effective diameter and a shutoff member including a male cylindrical shaft of the effective diameter that fits slidingly in the internal bore, and of a member extending as far as a pointed end provided with a mobile seat and forming the bottom end of the mobile member. The mobile member is hydraulically balanced and the length between the top end and the bottom end thereof is variable as a result of the sliding of the cylindrical shaft in the internal bore of the piston.

Abstract: A mobile valve member designed to be arranged in the nozzle body of a fuel injector, extends along a main axis and includes a piston formed of a first male cylinder of effective diameter forming the top end of the mobile member and of a second cylinder provided with an internal cylindrical bore of the effective diameter and a shutoff member including a male cylindrical shaft of the effective diameter that fits slidingly in the internal bore, and of a member extending as far as a pointed end provided with a mobile seat and forming the bottom end of the mobile member. The mobile member is hydraulically balanced and the length between the top end and the bottom end thereof is variable as a result of the sliding of the cylindrical shaft in the internal bore of the piston.

Abstract: A fuel injector includes a nozzle body having a spray tip with at least one spray orifice and a needle slideably arranged in the nozzle body in order to control the spray orifice. A control chamber is associated with the needle, which is filled with high-pressure fuel in order to exert a pressure force on the needle in its closing direction; the control chamber being in communication with a high pressure fuel channel through an inlet restrictor and with a low pressure drain through an outlet restrictor via a control valve to selectively allow or hinder the flow of fuel out of the control chamber through the outlet restrictor. The inlet restrictor and outlet restrictor are designed so that the ratio of outlet fuel flow rate over inlet fuel flow rate increases at low fuel temperatures, in order to cause a greater pressure reduction in the control chamber.

Abstract: A fuel injector includes a nozzle body having a spray tip with at least one spray orifice and a needle slideably arranged in the nozzle body in order to control the spray orifice. A control chamber is associated with the needle, which is filled with high-pressure fuel in order to exert a pressure force on the needle in its closing direction; the control chamber being in communication with a high pressure fuel channel through an inlet restrictor and with a low pressure drain through an outlet restrictor via a control valve to selectively allow or hinder the flow of fuel out of the control chamber through the outlet restrictor. The inlet restrictor and outlet restrictor are designed so that the ratio of outlet fuel flow rate over inlet fuel flow rate increases at low fuel temperatures, in order to cause a greater pressure reduction in the control chamber.