Compound spark-ignition and diesel engine

Claim 1

A compound rotary engine comprising: a. an outer body having an internal cavity, the peripheral surface of which has a multi-lobe profile, said outer body also having an air intake passage and a combustion gas exhaust passage; b. an inner body of generally polygonal profile mounted for relative rotation within said outer body, the apex portions of said inner body having sealing cooperation with said multi-lobe surface to define a plurality of working chambers which vary in volume in response to said relative rotation, the volumetric compression ratio of said working chambers being substantially less than that required for diesel-type operation; c. a fuel nozzle mounted on said outer body for discharging fuel into each working chamber after the air charge therein has been substantially compressed; d. ignition means for igniting fuel discharged into each working chamber by said fuel nozzle such that the engine is capable of operating with diesel-type fuels as a spark-ignited engine; and e. a supercharger driven by the engine exhaust gases discharging from said exhaust passage for supplying compressed air to said air intake passage, the supercharger output pressure being incapable below a predetermined engine power output, which is significantly above idling output, of raising the compression pressure in said working chamber to a value high enough for diesel-type operation but at higher engine power outputs being capable of raising the compression pressure in said working chambers to a value high enough for diesel-type operation.