| 摘要 |
PURPOSE:To make plural valve gears so as to become useless, by performing an EGR with a single valve gear in time of light load, while letting a part of boosted charging escape to the atmosphere when the boosted pressure of a turbocharger reaches a specified value. CONSTITUTION:In time of light load in an engine 2, a magnet solenoid 20 is energized by a signal of a control unit 21, while a valve body 17a of a valve 17 is opened, interconnecting a suction bypass valve 4 and an exhaust pipe 12 together through and making a part of exhaust gas flow back, whereby harmful components in the exhaust gas are reduced. Next, when load grows large, the solenoid 20 is unenergized. In addition, when further the load goes up and the boosted pressure by a turbocharger 3 exceeds the specified value, high pressure air is fed to a valve chest 19 from a branch pipe 18, opening the valve 17 against compression spring 23 and interconnecting the suction bypass 4 and the exhaust pipe 12 together through, and part of the high pressure air is discharged to the exhaust pipe 12, so that any damage to the engine 2 is prevented. Thus, the engine can be simplified in structure. |
