PURPOSE: To keep stable combustion with proper switching timing, by detecting the opening of a stop valve, switching the position of the stop valve at first at the time of changing the number of operated cylinders, and changing an injection constant and cylinders to which fuel is to be supplied.
CONSTITUTION: In case that low-load condition is continued for a prescribed while at the time of full-cylinder operation of an engine, an instruction is given at first to close a stop valve 11, and the valve 11 is closed after passing of a time T1+T2. Here, a means is provided for detecting the opening of the stop valve 11. When it is detected from the output signal of said opening detecting means that the opening of the stop valve 11 has reached a prescribed value, instruction are given to change an injection constant K and cylinders to which fuel is to be supplied. That is, fuel injection valves (a)W(c) of cylinders AWC which are to be rendered inoperative are closed completely, and the injection quantity of fuel injection valves (d)W(f) for operated cylinders DWF are almost doubled. Further, in case that partial-cylinder operation enters into a high- load region and it is continued for a prescribed while, an instruction is given at first to open the stop valve 11 and switching is made reversely to supply fuel to all of the cylinders AWF at an ordinary rate.
INOUE MITSUMASA
ISHIZAWA SHIZUO
KAMEGAYA SHIGERU
