Fuel injector

An injection nozzle of a high-pressure fuel injector, the injection nozzle comprising:

• a nozzle body that is elongate along a main axis and that has a cylindrical lateral peripheral wall that is tapered at one end, and an upper wall at the other end, the upper wall having a pressurized fuel inlet orifice and an axial through-bore forming an annular guide such that the axial through-bore has an effective diameter, the tapered end being formed on an inner face of the cylindrical lateral peripheral wall of the nozzle body of a static seat arranged close to injection holes extending across the cylindrical lateral peripheral wall;
• and
• a mobile valve member extending along the main axis between a top end and a bottom end that is provided with a mobile valve seat designed to cooperate with the static seat of the nozzle body about a circular line of the effective diameter, the mobile valve member being designed to slide between a closed position in which the mobile valve seat and the static seat are in sealing contact about the circular line to prevent fuel injection, and an open position in which the mobile valve seat and the static seat are separated from one another to enable fuel injection, the mobile valve member comprising:
• a piston made up of a first male cylinder of the effective diameter forming the top end of the mobile member and a second cylinder with an external diameter that is greater than the effective diameter, the second cylinder provided with an internal cylindrical bore having the effective diameter extending axially in the second cylinder as far as a back face;
• and
• a shutoff member made up of a cylindrical body comprising a male cylindrical shaft having the effective diameter that fits slidingly with a clearance in the internal cylindrical bore of the piston, and a male pointed cylindrical member with a diameter that is greater than the effective diameter, the male pointed cylindrical member extending as far as a pointed end including the mobile valve seat and forming the bottom end of the mobile valve member;
• wherein the mobile valve member is hydraulically balanced and a length between the top end and the bottom end thereof is variable as a result of a sliding of the male cylindrical shaft in the internal cylindrical bore of the piston;
• and
• wherein the mobile valve member is arranged axially to slide in an internal space of the nozzle body, the first male cylinder of the piston fitting slidingly with a clearance in the annular guide, such that the mobile valve seat cooperates with the static seat and that the mobile valve member slides along the main axis between the closed position and the open position in which the mobile valve seat is separated from the static seat.

A fuel injector comprising:

• an actuator;
• and
• an injection nozzle comprising:
• a nozzle body that is elongate along a main axis and that has a cylindrical lateral peripheral wall that is tapered at one end, and an upper wall at the other end, the upper wall having a pressurized fuel inlet orifice and an axial through-bore forming an annular guide such that the axial through-bore has an effective diameter, the tapered end being formed on an inner face of the cylindrical lateral peripheral wall of the nozzle body of a static seat arranged close to injection holes extending across the cylindrical lateral peripheral wall;
• and
• a mobile valve member extending along the main axis between a top end and a bottom end that is provided with a mobile valve seat designed to cooperate with the static seat of the nozzle body about a circular line of the effective diameter, the mobile valve member being designed to slide between a closed position in which the mobile valve seat and the static seat are in sealing contact about the circular line to prevent fuel injection, and an open position in which the mobile valve seat and the static seat are separated from one another to enable fuel injection, the mobile valve member comprising:
• a piston made up of a first male cylinder of the effective diameter forming the top end of the mobile member and a second cylinder with an external diameter that is greater than the effective diameter, the second cylinder provided with an internal cylindrical bore having the effective diameter extending axially in the second cylinder as far as a back face;
• and
• a shutoff member made up of a cylindrical body comprising a male cylindrical shaft having the effective diameter that fits slidingly with a clearance in the internal cylindrical bore of the piston, and a male pointed cylindrical member with a diameter that is greater than the effective diameter, the male pointed cylindrical member extending as far as a pointed end including the mobile valve seat and forming the bottom end of the mobile valve member;
• wherein the mobile valve member is hydraulically balanced and a length between the top end and the bottom end thereof is variable as a result of a sliding of the male cylindrical shaft in the internal cylindrical bore of the piston;
• wherein the mobile valve member is arranged axially to slide in an internal space of the nozzle body, the first male cylinder of the piston fitting slidingly with a clearance in the annular guide, such that the mobile valve seat cooperates with the static seat and that the mobile valve member slides along the main axis between the closed position and the open position in which the mobile valve seat is separated from the static seat;
• and
• wherein the actuator is an electromagnet including a static coil and a mobile magnetic armature attached directly to the piston.