Electromagnetic solenoid has movable core having end surface that is formed between inner circumferential surface and outer circumferential surface of movable core; and fixed core having end surface that is formed between inner circumferential surface and outer circumferential surface of fixed core and faces the end surface of movable core. Ring-shaped protruding portion is formed at least either one of the end surface of the movable core or the end surface of the fixed core. Protruding portion is provided at a position that is shifted to a radially inner circumferential side of the end surface. A length between apex and inner circumferential edge of protruding portion is shorter than a length between the apex and an outer circumferential edge of protruding portion.

A fuel injector includes an injector body and a valve stack within the injector body that includes a valve seat plate. The valve seat plate includes a pressure control passage for controlling fuel injection, and a valve seat positioned fluidly between the pressure control passage and a low-pressure drain. The valve seat plate includes a pressure-limiting annular groove that extends circumferentially around the valve seat and axially inward from a side of the valve seat plate where the valve seat is located. The groove enables deformation in response to pressure differences across the valve seat plate in a manner that limits stress concentrations.

The present invention includes a valve seat and a valve body that cooperatively open/close a fuel passage, a movable element having the valve body provided at one end part thereof and a movable iron core 27a provided at the other end part thereof, a fixed iron core 25 which faces the movable iron core 27a and which attracts the movable iron core 27a by applying a magnetic attraction force thereto, and a cylindrical member that includes thereinside the fixed iron core 25 and the movable iron core 27a. The fixed iron core 25 includes a reduced-diameter part 25m on an outer circumferential surface at the side facing the movable iron core 27a, and the movable iron core 27a includes a reduced-diameter part 27am on an outer circumferential surface at the side facing the fixed iron core 25.

When injection-hole inlets and injection-hole outlets are projected vertically onto an X-Y plane (N) perpendicular to a valve-seat axial center, an injection-hole arrangement angle (), which is formed by a straight line (a) passing through a center of the injection-hole inlet of a reference injection hole and the valve-seat axial center and a straight line (b) passing through a center of the injection-hole inlet of the injection hole neighboring the reference injection hole and the valve-seat axial center on the plane (N), is set so as to become smaller as being closer to a Y-axis. A fuel turn angle () on a wide-angle side, which is formed by the straight line (a) and a straight line (c) passing through a center of the injection-hole inlet and a center of the injection-hole outlet on the plane (N), has a relationship: 90<<180.

A valve assembly for an injection valve includes a valve body having a cavity with a fluid inlet portion and a fluid outlet portion, a valve needle axially movable in the cavity between a closing position preventing a fluid flow through the fluid outlet portion and further positions releasing the fluid flow through the fluid outlet portion, an electro-magnetic actuator unit that actuates the valve needle, and includes an axially movable armature in the cavity and a disc element fixedly coupled to the valve needle and configured to limit the axial movement of the armature relative to the valve needle towards the fluid outlet portion. An armature spring biases the armature away from the disc element for establishing a fluid-filled gap between the armature and the disc element. The armature is axially displaceable towards the disc element against the armature spring bias to reduce an axial size of the gap.

A gas fuel injector is provided, comprising a main body with an internal fuel passage, an opening/closing valve, and a solenoid for actuating the valve. The valve includes a shaft with a proximal end fixed to a solenoid plunger, a valve body at the distal end, and a valve seat member facing the valve body. The valve seat member includes a central valve hole, an annularly projecting peripheral wall, and an annular seat surface at the distal end of the wall. The valve body includes a sealing surface with a tapered, arched, or spherical shape that contacts the seat surface when the valve is closed.