Abstract: A rotary piston engine including a casing comprised of three rotor housings, intermediate housings between the rotor housings and side housings attached to the outer sides of the outer side housings. An eccentric shaft assembly is provided for carrying rotors in the casing. The eccentric shaft assembly includes a first shaft and a second shaft which are connected together with one end of the second shaft located in one of the intermediate housings. The housings of the casing are connected together by first tightening bolts which are inserted through the housing at one side of the one intermediate housing and threaded to the one intermediate housing and second tightening bolts which are inserted through the housings at the other side of the one intermediate housing and threaded to the one intermediate housing.

Abstract: A vibration detecting apparatus including a vibration detector for detecting engine vibrations in a multi-rotor rotary piston engine. The vibration detector is disposed on an intermediate housing, on both sides of which working chambers of the multi-rotor piston engine are formed. The vibration detector is located so that it has a sensitivity to vibration in the direction substantially perpendicular to the side surface of the intermediate housing, and parallel to the axial direction of the eccentric shaft which carries the rotors. By the above arrangement of the vibration detector, the vibrations are precisely detected. In response to the detected vibrations, it is possible, for example, to control engine knocking.