| 摘要 |
PURPOSE:To enable reduction of production of noise and vibration, by a method wherein, during low speed and low load running, according to a detecting result of noise and vibration, a fuel injection rate is decreased. CONSTITUTION:In an electric control circuit 2, when a given condition is satisfied by means of signals from an accel control amount detector 1a, a number of revolutions detector 1b, and a key switch 81, control of the number of idle revolutions is executed. In which case, an upper limit and a lower limit of an allowable noise level decided by means of the number of revolutions are calculated. An output from a microphone 9, detecting noise of an engine 6, is inputted to a peak hold circuit 23. A peak valve of a current noise level is compared with an allowable noise level, and the value of a current flowing to an injection pressure control valve 70 is corrected by a current control circuit 21 so that a current level enters within a range of an allowable level. A coil 73 of the injection pressure control valve 70 is energized for control by a current control circuit 21, and the relief pressure of a high pressure chamber 56 is set by pressing a plunger 72 against a sheet part 71a by means of an electromagnetic force and a return spring 74.
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