THE WANKEL ROTARY ENGINE 7.1 A Different …（7.1转子活塞引擎不同u2026）.pdf

261 C H A P T E R 7 THE WANKEL ROTARY ENGINE 7.1 A Different Approach to the Spark-Ignition Engine The reciprocating internal combustion engine has served mankind for over a century, and will continue to do so for the foreseeable future. The Wankel rotary engine, a much more recent development, is said to have been conceived in its present form in 1954 (ref. 2). An implementation of the rotary engine used in the 1990 Mazda RX-7 automobile and its turbocharger are shown in Figures 7.1(a) and 7.1(b). As of 1987, over 1.5 million Wankel engines had been used in Mazda automobiles (ref. 6). The rotary engine has a host of advantages that make it a formidable contender for some of the tasks currently performed by reciprocating engines. The piston in a four- stroke-cycle reciprocating engine must momentarily come to rest four times per cycle as its direction of motion changes. In contrast, the moving parts in a rotary engine are in continuous unidirectional motion. Higher operating speeds, ease of balancing, and absence of vibration are a few of the benefits. The high operating speeds allow the engine to produce twice as much power as a reciprocating engine of the same weight. It has significantly fewer parts and occupies less volume than a reciprocating engine of comparable power. With all these advantages, why are there so few Wankel engines in service? Part of the answer lies in the reciprocating engineís remarkable success in so many applications and its continuing improvement with research. Why change a good thing? Manufacturing techniques for reciprocating engines are well known and established, whereas production of rotary engines requires significantly different tooling. It must be admitted, however, that the rotary engine has some drawba