What is a three-rotor?

The triangular rotor typically refers to a three-rotor engine, featuring an ignition system and fuel supply mechanism similar to those found in piston engines.

　　The three-rotor engine, like a car’s engine, is an internal combustion engine—but it operates entirely differently from a traditional piston engine. In a piston engine, the same space (the cylinder) must sequentially perform four distinct tasks: intake, compression, combustion, and exhaust. While the rotary engine also completes these four processes, each task is handled in its own dedicated housing. It’s almost as if every step has its own dedicated "cylinder," with the rotor continuously moving from one "cylinder" to the next—much like a piston shuttling back and forth between individual cylinders.

　　Who is the inventor of the three-rotor device?

　　The three-rotor engine was invented by Dr. Felix Wankel, which is why it’s also known as the Wankel engine or the Wankel rotary machine.

　　In this article, we'll explore the principles of rotor machines. Let's start with the basics.

　　Like piston engines, rotary engines also rely on the pressure generated by the combustion of an air-fuel mixture. In a piston engine, this pressure is contained within the cylinder, driving the pistons to move. The connecting rods and crankshaft then convert the pistons' reciprocating motion into rotational movement, which ultimately powers the vehicle.

　　In a three-rotor engine, the pressure generated by combustion is contained within a sealed chamber formed by the housing and a triangular rotor (which replaces the piston in this machine).

　　The rotor and housing of Mazda's RX-7 rotary engine—these components replace the pistons, cylinders, valves, connecting rods, and camshaft found in a conventional piston engine.

　　The rotor's movement path closely resembles the trajectory generated by the breathing mechanism. The rotor's apex continuously touches the housing, creating three distinct air chambers. As the rotor spins around the combustion chamber, the gases within these three chambers alternately expand and contract. It is this expansion and contraction that draws air and fuel into the engine, subsequently compressing the resulting mixture. When the gas expands again, it generates useful power, while the exhaust gases are expelled from the system.

　　Next, we’ll take a closer look inside the rotary engine to explore its individual components. First, let’s examine the new model equipped with the innovative rotary engine.

　　Mazda RX-8

　　Mazda has long been a pioneer in developing mass-produced vehicles powered by rotary engines. The RX-7, introduced to the market in 1978, was perhaps the most successful car to feature this innovative technology. But before that, Mazda had already rolled out a range of rotary-engine-powered cars, trucks, and even buses—starting with the speedy Cosmo Sport in 1967. Although the RX-7 was discontinued from the U.S. market in 1995, rotary engines are undoubtedly set to make a comeback in the near future.

　　The Mazda RX-8 is Mazda's new sedan, equipped with the innovative RENESIS rotary engine. This engine won the 2003 International Engine of the Year award. It’s a naturally aspirated, twin-rotor engine delivering an impressive output of around 250 horsepower.