| 摘要 |
PURPOSE:To obtain a satisfactory rise characteritic of ignition timing at the time of an EGR operation by a method wherein a passage branched from a negative- pressure passage for operating an EGR valve is provided with a check valve so as to seal in the negative pressure on the distributor side. CONSTITUTION:The check valve 40 is provided between a negative-pressure change-over valve 30 and the branching part 8a of the negative-pressure passage 8 which is branched from the negative-pressure passage 7 connecting the EGR valve 20 and the change-over valve 30, in such a manner as to seal in the negative pressure on the distributor 1 side. Even when the negative pressure at an EGR port 6 is in excess of a set point for the EGR operation and the EGR is being carried out, the negative pressure may not be sufficiently high in some cases. Even in such cases, the interior of the second diaphragm chamber 14 for the distributor 10 is maintained at a sufficiently high negative pressure by the check valve 40. Accordingly, the characteristics required for the ignition timing at the time of EGR operation can be sufficiently satisfied. |
