PURPOSE: To increase the limit of knocking and upgrade combustion efficiency by changing EGR volume in proportion to the generating conditions of load and knocking.
CONSTITUTION: Under a supercharging operating condition where the generation of knocking is very severe, a supercharging pressure of an inlet mainfold 7 is applied to a diaphragm chamber 42 above an EGR valve 13. As a result, a valve stem 29 fastened to a diaphragm 31 makes a sliding motion in the direction of A. Therefore, a valve 28 is separated from a valve seat 27, and pipes 14 and 15 are communicated to each other and exhaust gas is recirculated in an air intake pipe 7. This EGR decreases combustion speed and relieves the limit of knocking. When the knocking occurs actually, a knocking sensor 21 detects the generation of knocking detection circuit 22 feeds a pulse output signal to a negative pressure change over valve 23. The supercharging pressure of the air intake manifold 7 is applied to a lower diaphragm 34, thereby increasing the EGR volume, and reducing the generation of knocking.
SHIMIZU KOUICHI
TAKAKUWA EIJI
NAKANO KAZUMI
