INTERNAL COMBUSTION ENGINE CAPABLE OF CONTROLLING NUMBER OF OPERATING CYLINDERS

摘要

PURPOSE:To provide an internal combustion engine, which is designed such that air instead of exhaust gas is introduced into the passage communicated to non-operating cylinders, during low-load operation of engine when difference of suction pressure in the passage communicated to non-operating cylinders and the passage communicated to normally-operating cylinders becomes considerably great, whereby it is enabled to prevent degradation of engine performance due to leakage of exhaust gas to the normally-operating cylinders. CONSTITUTION:During low-load operation of engine, vacuum switch 38 is turned on and three- way electromagnetic valves 36, 37 are both energized. One electromagnetic valve 36 closes atmosopheric port 36c and communicates ports 36a and 36b with each other, so that vacuum is acted in vacuum chamber 25 of vacuum-responsive valve 22, thus opening the valve 22 to its full extent. The other electromagnetic valve 37, on the other hand, closes port 37a and communicates ports 37c and 37b with each other, so that atmospheric pressure is acted in vacuum chamber 27 of vacuum-responsive valve 23, thus fully closing the valve 23. With such an arrangement, air instead of exhaust gas is introduced into passage 8 communicated to non-operating cylinders and pressure in the passage 8 is kept at atmospheric pressure, so that pumping loss can be avoided.