| 摘要 |
A fuel injector comprising an outer valve needle (14) provided with a bore (17), an inner valve needle (18) slidable within the bore (17), the outer and inner valve needles (14, 17) being engageable with first and second seatings (13, 21) respectively to control the supply of fuel from the fuel injector. The inner valve needle (18) includes a passage (26, 28) which communicates with a sac chamber (23) located downstream of the second seating (21), whereby movement of the outer valve needle (14) away from the first seating (13) causes fuel to flow through the passage (26, 28) into the sac chamber (23) such that fuel pressure within the sac chamber (23) causes the inner valve needle (18) to lift away from the second seating (21). |
