| 摘要 |
A fuel injector which, under the control of the engine ECM, may control the shape of the fuel injection event profile. Such control is achieved by varying the magnitude of a control current applied to the injector. The control current in turn varies the bias force applied to a needle valve in the injector nozzle, thereby changing the shape of the injection event profile in proportion to the amount of control current applied. In a preferred embodiment, control of the bias force is achieved by placing a piezoelectric actuator between the needle valve and a bias spring. The length of the piezoelectric actuator changes in proportion to the amount of control current applied thereto, thereby changing the bias force applied to the needle valve. The profile is preferably altered in relation to engine speed.
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