PURPOSE: To prevent blowing back to dead volume at a low speed by providing a communication passage communicating the upstream of a timing valve in an auxiliary intake air passage to the downstream of a check valve in a main intake air passage and further providing this communication passage with a closing valve.
CONSTITUTION: A main intake air passage 4 and an auxiliary intake air passage 8 are connected to a rotary piston engine 1. A timing valve 16 opening in the latter half of an opening period of an auxiliary air intake port 10 is provided in the downstream of a supercharger 9, and a check valve 20 which prevents blowing back from an operation chamber A side is provided in a main intake air passage 4. Further, a closing valve 22 which is opened when the engine rotational frequency exceeds a set value is provided in a communication passage 21. During a high-speed operation of an engine, pressurized air is supplied to the operation chamber A for supercharging via the communication passage 21 and a main air intake port 5. At this time, since the main air intake port 5 is closed before the auxiliary air intake port 10 is closed, blowing back in the latter period of an air intake stroke can be effectively prevented.
OKIMOTO HARUO
MATSUDA IKUO
