| 摘要 |
PURPOSE:An EGR apparatus which allows the reduction of NOX constituent in exhaust gas and the prevention of deterioration of operation characteristic. CONSTITUTION:When the atmospheric pressure lowers, an atmospheric-pressure sensing valve 17 is closed. This operation allows the negative pressure in a fixed value to be applied to a path 15, and said negative pressure is applied to the subchamber 16 of an EGR valve 10, so a movable disc 29 shifts to the top end position of a cylindrical element 28, and a spring 27 is elongated. Consequently, the absolute negative pressure for the valve opening operation on the EGR valve 10 lowers. Thus, even if high load operation is performed on highland, and the absolute negative pressure applied to a diaphragm chamber 11 decreases lower than the fixed value for valve opening operation of flatland, the EGR valve 10 is left opened, and EGR control is performed as it is. That is, on highland, the domain on which EGR control is performed expands in comparison to the case on flatland. |
