| 摘要 |
PURPOSE:To prevent deposit from sticking inside an exhaust chamber of a pressure resulation valve and to allow the controller available with lead gasoline by bleeding atmosphere into the exhaust chamber to scavenge the same when EGR is OFF. CONSTITUTION:When control negative pressure from a pressure regulation valve 22, applied in a diaphragm chamber 32 of an EGR valve 20, yields to a specific force of a compression spring 34 which is disposed inside the diaphragm chamber 32, a vacuum switch 72 is turned ON. Responding to the ON signal, VSV74 is opened. At the opening of VSV74, atmosphere is bled into both an exhaust chamber 46 of the pressure regulation valve 22 and a constant pressure chamber 40 of the EGR valve 20 via respective primary and secondary check valves 76 and 78 with the aid of pulsated exhaust gas to scavenge both the chambers. On the other hand, when EGR is ON, the vacuum switch 72 is kept OFF so that VSV 74 is closed. |
