| 摘要 |
An internal combustion engine fuel injector ( 1 ) has a rod ( 10 ) movable along an axis ( 3 ) to open/close a nozzle, and a servovalve ( 7 ) having a control chamber ( 23 ) with a discharge passage ( 26, 48 ) which is opened/closed by a shutter ( 17 ) movable axially under the control of an electro-actuator; the servovalve also has a fixed axial rod ( 33 ) having an outer lateral surface ( 34 ) through which the discharge passage ( 26, 48 ) comes out; the shutter ( 17 ) is fitted to the axial rod ( 33 ) to slide axially in substantially fluidtight manner, and, when closing the discharge passage ( 26, 48 ), is subjected to substantially zero resultant axial pressure by the fuel; and a calibrated portion ( 42, 52 ) of the discharge passage ( 26, 48 ) is formed close to the outlet of the discharge passage to produce swirl and/or cavitation in the fuel outflow near to the closing area between the shutter ( 17 ) and the axial rod ( 33 ).
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