Is vaccine against HCV possible

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.