Valve for metering a fluid, especially a fuel injector
A valve (or fuel injector), which provides that the valve-seat member exhibits high structural strength and fatigue strength under vibratory stresses, includes an excitable actuator for actuating a valve-closing member which, with a valve-seat face on the valve-seat member, forms a sealing seat, and injection openings which are downstream of the valve-seat face, the injection openings being in a center area of the valve-seat member projecting outwardly dome-like in the injection direction. The dome-like center area has a curved outer contour, the curvature in a radially inner section having a larger radius than the radius of the curvature in a radially outer section of the dome, which ends radially outside the mouth areas of all injection openings, in a recessed depression, that is followed radially outwardly by an axially projecting edge area of the valve-seat member. The fuel injector directly injects fuel into a combustion chamber of an engine.
1. A fuel injector, which is a valve for metering a fluid, for directly injecting fuel into a combustion chamber, for a fuel injection system of an internal combustion engines, comprising:
an excitable actuator to actuate a valve-closing member which, together with a valve-seat face formed on a valve-seat member, forms a sealing seat, and including at least one injection opening which is formed downstream of the valve-seat face, the at least one injection opening being placed in a center area of the valve-seat member projecting outwardly in a dome-like manner in the injection direction;
wherein the dome-like center area of the valve-seat member has a curved outer contour, the curvature in a radially inner section having a larger radius than the radius of the curvature in a radially outer section of the dome, which ends radially outside of the mouth areas of all injection openings, in a recessed depression, that is followed radially outwardly by an again axially projecting edge area of the valve-seat member.
2. The fuel injector of claim 1 , wherein in cross-section, an overall wave-shaped dome contour of the valve-seat member is formed, the center area appearing as a flattened dome because of the variability in radius.
3. The fuel injector of claim 1 , wherein the dome-like center area is formed to be axially symmetrical relative to a longitudinal valve axis, and the depression runs circumferentially accordingly.
4. The fuel injector of claim 3 , wherein the circumferential recessed depression is notched like an annular bead.
5. The fuel injector of claim 1 , wherein the depression and/or the transition from the radially outer depression edge to the edge area is sharp-edged or rounded.
6. The fuel injector of claim 1 , wherein the edge area has a flat and even end face.
7. The fuel injector of claim 1 , wherein the wall thickness of the center area of the valve-seat member varies in the radial direction, the wall thickness being less in the radially inner section than in the radially outer section of the dome.
8. The fuel injector of claim 7 , wherein the wall thickness in the radially outer section of the center area is greater by approximately 20 to 250% than the wall thickness in the radially inner section of the center area.
9. The fuel injector of claim 1 , wherein material thickenings are provided in the region of the injection openings.
10. The fuel injector of claim 1 , wherein the center area, surrounded radially by the depression, is either offset back or placed forward in terms of its axial extension relative to the radially outwardly extending edge area of the valve-seat member, or both areas lie with their end faces in roughly one and the same plane, the bottom of the depression always being offset back relative to the end face.
11. The fuel injector of claim 1 , wherein between two and thirty injection openings are provided in the valve-seat member.