FUEL INJECTION NOZZLE

摘要

In a nozzle, in a cross section including an axis of a nozzle body, a side surface and a seat surface are both smoothly connected to an arc of a circle inscribing both the side surface and the seat surface. A part of a needle which is adjacent to a tip end side of a seat portion is a cone having a diameter reduced toward a tip end side of the cone in the axial direction. Thus, no corner is on the seat surface or the side surface, and the two surfaces form one curved surface. Since a cavitation generated in a sack chamber can be reduced, even when an injection quantity is significantly small such that an injection port does not throttle an injection flow, a flow coefficient of the injection flow is improved and a penetration of a spray of the fuel can be maintained.

主权项

1. A fuel injection nozzle comprising:
a nozzle body being a cylindrical shape; a needle received in the nozzle body, the needle being slidable relative to an inner periphery of the nozzle body in an axial direction of the nozzle body, wherein the inner periphery of the nozzle body includes a seat surface, the needle includes a seat portion, the seat portion is removed from or seated on the seat surface to start or stop a fuel injection using an injection port disposed at a tip end side of the seat surface in the axial direction, the seat surface is a tapered shape, a diameter of the seat surface is reduced toward the tip end side of the seat surface in the axial direction, a sack chamber is disposed at a position adjacent to the tip end side of the seat surface, the sack chamber includes an inlet of the injection port, a sack surface defining the sack chamber includes a side surface and a bottom surface, the side surface has a sharper slope than the seat surface and is coaxial with the seat surface, the bottom surface is a curved shape and covers the sack chamber at a tip end side of the side surface in the axial direction, the side surface and the bottom surface are smoothly connected to each other, a part of the needle which is adjacent to a tip end side of the seat portion is a cone having a diameter reduced toward a tip end side of the cone in the axial direction, and in a cross section including an axis of the nozzle body, the side surface and the seat surface are both smoothly connected to an arc of a circle inscribing both the side surface and the seat surface.