The Szorenyi Three-Chamber Rotary Engine Concept

Currently automotive engines are reciprocating or Wankel rotary engine types. Reciprocating engines are bulky, heavy and complex, mainly due to the intake and exhaust valves and their associated cam-train. Wankel engines have a low rotor rev limit, and have inefficient sealing of the apex seals leading to poor economy and undesirable emission gases. The Rotary Engine Development Agency (REDA) has designed a new three-chamber rotary internal combustion engine concept using an adaptation of the patented Szorenyi Curve. The new design is an evolution of the design which was the subject of SAE Technical Paper 2017-01-2413 and SAE publication ‘So You Want to Design Engines: UAV Propulsion Systems’. This paper describes the features of the new three-chamber engine concept and includes an analysis of the major shortcomings of the Wankel engine. The Wankel engine’s geometry results in excessive crankshaft deflection at high engine revs due to the centrifugal force of the rotor which is eccentric to the crankshaft. This results in a low rotational speed limit. Analysis of the Wankel design reveals that the rotational speed limit cannot be increased by increasing the diameter of the crankshaft. Also, analysis of the apex seal reveals that the shape of the stator accelerates the seal inwards during the intake and power stroke and, at the same time, the seal experiences a large change in its contact angle with the stator surface. These effects combine to produce poor conditions for sealing the combustion chamber of the Wankel engine. The paper identifies that the Szorenyi three-chamber engine design does not have these same issues because its symmetrical rotor enables a high rotational speed, and its continuously concave stator profile ensures an outward acceleration of the apex seal and much less change of contact angle with the stator surface. The paper concludes that the Szorenyi engine has the potential to replace Wankel and reciprocating engines in a range of applications and is particularly suited to light aircraft.