Abstract: A four-rotor type rotary piston engine including an eccentric shaft assembly composed of three elements; a main eccentric shaft defining the rotational axis of each rotor and first and second auxiliary eccentric shafts coupled to opposite end of the main eccentric shaft. The auxiliary eccentric shafts and the main eccentric shaft art fitted by tapered surfaces and have a small clearance therebetween in the radial direction to enable smooth coupling. The main eccentric shaft has two rotor eccentric journals for the second and the third cylinders. At first, the second and the third cylinders are installed. After that, the auxiliary eccentric shafts having rotor eccentric journals are coupled with the main eccentric shaft, and finally the first and the fourth cylinders are installed.

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.