Engine fuel injection valve and manufacturing method for nozzle plate used for the same injection valve

A fuel injection valve comprising:

• a substantially cylindrical valve casing in which a fuel flow passage is provided in its axial direction;
• a valve seat member comprising a valve seat installed within the fuel flow passage of one end of the cylindrical valve casing to enable a seating of a valve body and an injection outlet opening with a periphery of which the valve seat is enclosed, the valve body being disposed within the fuel flow passage of the valve casing to be operatively separated from the valve seat to open the fuel injection valve to inject the fuel in the fuel flow passage of the valve casing in response to an activation of an actuator;
• a nozzle plate faced against the injection outlet opening and on both surfaces of which openings of a plurality of nozzle holes are formed, the fuel being injected through the nozzle holes when the fuel injection valve is open;
• and
• a chamfered portion formed on an edge of an inner wall portion of each opening end of the corresponding nozzle hole of the nozzle plate to further expand a whole diameter of an injection stream of fuel passed through the nozzle holes, a cross section of the chamfered portion being in a substantially arc shape of convex geometry with respect to a central axis of the corresponding nozzle holes;
• wherein the dimension ratio between a hole diameter of each nozzle hole (d) at a substantially center of its corresponding nozzle hole and a radius of curvature of its corresponding arc-shaped chamfered portion (r) at the corresponding opening end is set to fall in a range from 1:0.1 to 1:0.28.

A fuel injection valve comprising:

• a substantially cylindrical valve casing including an axial fuel flow passage;
• a valve seat member comprising a valve seat positioned in the fuel flow passage adjacent one end of the cylindrical valve casing to seat a valve body, the valve seat forming an injection outlet opening, the valve body configured to be operatively separable from the valve seat to open the fuel injection valve to inject the fuel in the fuel flow passage of the valve casing;
• and
• a nozzle plate facing the injection outlet opening, the nozzle plate having a plurality of nozzle holes formed therethrough, wherein fuel is injected through the nozzle holes when the fuel injection valve is open;
• wherein at least a plurality of the nozzle holes include a smoothly chamfered portion including a substantially arc shape cross section formed at an end of the nozzle hole smoothing out the end of the nozzle hole and to expand an injection stream of fuel passed through the nozzle holes;
• wherein the dimension ratio between a hole diameter of each nozzle hole (d) at a substantially center of its corresponding nozzle hole and a radius of curvature of its corresponding arc-shaped chamfered portion (r) at the corresponding opening end is set to fall in a range from 1:0.1 to 1:0.28.