Split operation type multi-cylinder internal combustion engine

Abstract

An internal combustion engine having a plurality of cylinders which are divided into a first cylinder group and a second cylinder group. The engine comprises a first throttle valve and a second throttle valve for controlling the amount of combustible mixture fed into the first cylinder group and the second cylinder group, respectively. The engine further comprises a first actuating means for rotating the first throttle valve faster when the engine load is low than when engine load is high, and for rotating the second throttle valve only when the engine load level is higher than a predetermined level. This first actuating means is energized only when the engine temperature is higher than a predetermined value. The engine further comprises a second actuating means for rotating both of the first and second throttle valves in accordance with the engine load level. This second actuating means is energized only when the engine temperature is equal to or lower than the above-mentioned predetermined value. Furthermore, the engine comprises control means for fully opening the second throttle valve and for stopping the supply of fuel to the second cylinder group, when the engine load level is lower than the above-mentioned level. This control means is energized only when the first actuating means is energized.