| 摘要 |
A hydraulically-actuated fuel injector (11) includes an injector body (15) that defines an actuation fluid inlet (32), a first actuation fluid passage (22), a second actuation fluid passage (23), a fuel inlet (31) and a nozzle outlet (30). A solenoid actuated control valve (16) is attached to the injector body (15) and includes a spool valve member (40) moveable between a first position and a second position. The actuation fluid inlet (32) is closed to the first actuation fluid passage (22) and open to the second actuation fluid passage (23) when the spool valve member (40) is in its first position. The actuation fluid inlet (32) is open to the first actuation fluid passage (22) and closed to the second actuation fluid passage (23) when the spool valve member (40) is in its second position. A piston (50) is positioned in the injector body (15) and moveable between a retracted position and an advanced position. The piston (50) has an upper end (51) exposed to fluid pressure in the first actuation fluid passage (22). A needle valve member (60) is positioned in the injector body (15) and moveable between an inject position in which the nozzle outlet (30) is open, and a closed position in which the nozzle outlet (30) is blocked. The needle valve member (60) has a closing hydraulic surface (61) exposed to fluid pressure in the second actuation fluid passage (23).
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