1. A fuel injection valve, comprising:
5 a valve seat member (3) having a conical valve seat (8) and a valve hole (7)
penetrating through a central portion of the valve seat at a front end of the valve seat
member;
a valve body (13) having at a front end of the valve body, a spherical valve
portion (14) which opens and closes the valve hole (7) in cooperation with the valve seat
10 (8); and
an injector plate (10) joined to a front end surface of the valve seat member (3)
and having a plurality of fuel injection holes (11) which are arranged radially outward
away from the valve hole (7) and communicate with the valve hole (7), characterized in
that,
15 a fuel collection chamber (49) connecting between the valve seat (8) and the
valve hole (7) is provided on the valve seat member (3), while a bottom surface of the
fuel collection chamber (49) is configured with a concave curved surface (49a) formed
along a spherical zone of a virtual spherical surface (B) in which a center (Bo) is placed
on a center line (Y) of the valve seat (8) and an intersection point (P) with the center line
20 (Y) is positioned within the valve hole (7), a flat fuel diffusion chamber (50)
communicating between the valve hole (7) and the plural fuel injection holes (11) is
formed integrally with the valve seat member between facing surfaces of the valve seat
member (3) and the injector plate (10), and an inner peripheral surface of the valve hole
(7) has a convex curved surface (7a) so as to be smoothly continuous with the bottom
25 surface of the fuel collection chamber (49) and a ceiling surface of the fuel diffusion
chamber (50).
2. The fuel injection valve according to claim 1, wherein the valve seat member
(3) has a guide hole (9) having a polygonal cross-section, which guides the
30 opening/closing operation of the spherical valve portion (14), and a plurality of fuel
12
passages (37) connected to the valve seat (8) are defined between a plurality of inner
corner potions (9b) of the guide hole (9) and the spherical valve portion (14).