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(11) | EP 1 164 283 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A fuel injection valve |
| (57) A fuel injection valve (10) is provided with a valve needle (105) which is urged
by the pressure of fuel in a control chamber (109) to a closed position where the
valve needle (105) closes the fuel injection hole (103). A supply passage (209) with
a throttled portion connects a high pressure fuel passage (123) to the control chamber
(109). The control chamber (109) is connected to a leak chamber (130) by two return
passages (201,203). The leak chamber (130) has a leak passage (117) for spilling fuel
in the leak chamber (130) to the outside of the fuel injection valve (10). A control
valve (300) is provided in the leak chamber (130). The control valve (300) is capable
of taking any of a closed position where the leak passage (117) is closed, a medium
lift position where the leak passage (117) and two return passages (201,203) are opened,
and a full lift position where the leak passage (117) and only one return passage
(201)are opened. In the closing position of the control valve (300), the pressure
in the control chamber (109) is high and the valve needle (105) is kept at the closing
position. In the medium lift position and the full lift position, fuel in the control
chamber (109) is spilled through the leak passage (117) via return passages (201,203)
and the leak chamber (130). This causes the valve needle (105) to move to the position
where the fuel injection hole (103) is opened. However, at the full lift position,
since only one return passage (201) is opened, the rate of the pressure drop in the
control chamber (109) is smaller and the speed of the lift of the valve needle (105)
is lower. Therefore, the fuel injection characteristics can be changed by switching
the position of the control valve (300) between the medium lift position and the full
lift position during fuel injection. |