Control valve arrangement of a fuel injector

1. A control valve arrangement of a fuel injector, the control valve arrangement comprising:

a valve body provided with a filling chamber in which pressurized fuel enters via a filling hole;

a filling valve arranged in the filling chamber for opening or closing a first fluid communication which controls filling with pressurized fuel of a first control chamber, the filling valve having a filling valve member moving along a valve axis, the filling valve member having a head provided with a moving valve seat and a stem slidably guided in a bore provided in the valve body, the filling valve member being normally biased open by a first spring;

a control valve having a control valve member cooperating with an actuator for opening or closing a second fluid communication which controls emptying of the first control chamber, the control valve member being normally biased closed by a second spring; and

a seat plug arranged in the valve body which closes the filling chamber, the seat plug being provided with an opening provided with a fixed valve seat which cooperates with the moving valve seat, the opening defining the first fluid communication between the filling chamber and the first control chamber;

wherein the seat plug is press fitted with interference within the filling chamber.

2. A control valve arrangement as claimed in claim 1 , wherein the seat plug is further provided with the filling hole.

3. A control valve arrangement as claimed in claim 1 , wherein an orientation of the filling hole is parallel to the valve axis.

4. A control valve arrangement as claimed in claim 1 , wherein the valve body is further provided with a section of a main feedhole extending axially, the main feedhole being adapted to flow pressurized fuel from upstream of the control valve arrangement into a volume arranged downstream of the control valve arrangement, the filling hole creating fluid communication between the volume to the filling chamber.

5. A control valve arrangement as claimed in claim 1 , further comprising a spring seat fixed to the filling valve member, the spring seat transmitting to the filling valve member an opening force generated by the first spring.

6. A control valve arrangement as claimed in claim 5 , wherein the spring seat is an annular collar fixed onto the stem of the filling valve member, the first spring being a coil spring compressed between a face of the valve body and the spring seat.

7. A control valve arrangement as claimed in claim 6 , wherein the spring seat is fixed with interference fit onto the stem of the filling valve member.

8. A control valve arrangement as claimed in claim 6 , wherein the stem is provided with a shoulder against which abuts the spring seat.

9. A control valve arrangement as claimed in claim 1 , wherein the filling hole is provided with a throttle orifice.

10. A control valve arrangement as claimed in claim 1 , wherein the bore in which the stem of the filling valve member is guided opens in a bottom wall of the valve body into the filling chamber.

11. A control valve arrangement as claimed in claim 10 , wherein the bottom wall of the valve body is provided with an annular undercut forming a groove surrounding the bore and defining a wall with an internal face which is the bore and with an external face which is the filling chamber.

12. A control valve arrangement as claimed in claim 11 , wherein the external face of the wall is conical, a thickness of the wall being thinner by an opening of the bore and enlarging as measured closer to a bottom of the groove.

13. A control valve arrangement as claimed in claim 1 , wherein the second fluid communication comprises a communication channel extending from the first control chamber to a second control chamber and, an evacuation channel extending from the second control chamber to an outlet line, the control valve being arranged between the second control chamber and the outlet line.

14. A fuel injector comprising:

a movable needle which cooperates with a nozzle to enable or prohibit fuel injection; and

a control valve arrangement which hydraulically pilots the movable needle, the control valve arrangement comprising:

a valve body provided with a filling chamber in which pressurized fuel enters via a filling hole;

a filling valve arranged in the filling chamber for opening or closing a first fluid communication which controls filling with pressurized fuel of a first control chamber, the filling valve having a filling valve member moving along a valve axis, the filling valve member having a head provided with a moving valve seat and a stem slidably guided in a bore provided in the valve body, the filling valve member being normally biased open by a first spring;

a control valve having a control valve member cooperating with an actuator for opening or closing a second fluid communication which controls emptying of the first control chamber, the control valve member being normally biased closed by a second spring; and

a seat plug arranged in the valve body which closes the filling chamber, the seat plug being provided with an opening provided with a fixed valve seat which cooperates with the moving valve seat, the opening defining the first fluid communication between the filling chamber and the first control chamber;

wherein the seat plug is press fitted with interference within the filling chamber.