Patent ID: 6666387
Filing Date: 2003-12-23
Classification: F02B,F02M,Y02T

Abstract:
A fuel injector of an internal combustion engine, comprising:a nozzle body having a nozzle hole formed in a tip of the nozzle body and a valve seat formed in the nozzle body upstream of the nozzle hole; a needle valve movable in a direction of an axis of the nozzle body to open and close the nozzle hole by moving the needle valve apart from the valve seat and by seating the needle valve on the valve seat; a swirler located upstream of the valve seat to give rotational momentum to fuel to be injected from the nozzle hole and to create swirling fuel flow; a projected portion whose inner peripheral wall is continuous with an inner peripheral wall surface of the nozzle hole, the projected portion being formed on an edge portion of an opening end of the nozzle hole so that a height of the projected portion, measured in a direction of an orifice axis of the nozzle hole, varies along a circumferential direction of the nozzle hole; the projected portion comprising: (i) a first sloped portion having a sloped surface that a height h1 of the sloped surface, measured in the orifice-axis direction, is dimensioned to gradually increase along a direction of the swirling fuel flow; and (ii) a second sloped portion having a sloped surface that a height h2 of the sloped surface, measured in the orifice-axis direction, is dimensioned to gradually decrease along the swirling-fuel-flow direction; a gradient of the sloped surface of the first sloped portion being defined by dh1/d&thgr; and a gradient of the sloped surface of the second sloped portion being defined by dh2/d&thgr;, in a &thgr;-h coordinate system corresponding to a cylindrical coordinate system in which a reference plane is defined as a plane normal to the orifice axis and cutting a section of the projected portion that the height of the projected portion becomes smallest, an intersection point between the orifice axis and the reference plane is chosen as an origin, an angular position of a point of the edge portion of the opening end of the nozzle hole with respect to the origin serving as a reference is represented by an angle &thgr; ranging from 0Â° to 360Â°, the height of the projected portion in the orifice-axis direction with respect to the reference plane serving as a reference is represented by a height h, a &thgr;-axis representing the angle &thgr; is taken as an axis of abscissa, and an h-axis representing the height h is taken as an axis of ordinate; and the projected portion being dimensioned to satisfy an inequality: |dh1/d&thgr;|max2/d&thgr;|max where |dh1/d&thgr;|max is an absolute value of a maximum value of the gradient of the sloped surface of the first sloped portion, and |dh2/d&thgr;|max is an absolute value of a maximum value of the gradient of the sloped surface of the second sloped portion.