Rotary engine
A rotary engine, also known as a Wankel engine, is an internal combustion engine characterized by its unique design, where a curved triangular rotor rotates within a housing instead of using traditional pistons. This design allows the rotary engine to efficiently combine the functions of intake, compression, combustion, and exhaust in a single movement, resulting in higher power output compared to conventional piston engines. Developed by Dr. Felix Wankel in the 1920s, the rotary engine gained attention in the 1960s when Mazda began refining and popularizing it, particularly in sports cars like the Cosmo Sport. While the rotary engine has advantages like fewer moving parts and a simpler manufacturing process, it also has notable drawbacks, including lower fuel efficiency, higher emissions, and potential reliability issues. Efforts have been made to mitigate these challenges, such as Mazda's exploration of hydrogen rotary engines and electric vehicles. Overall, the rotary engine remains a significant part of automotive engineering, attracting interest from car enthusiasts and engineers alike.
On this Page
Rotary engine
A rotary engine is an internal combustion engine with cylinders. It is also called a Wankel engine, or Wankel rotary engine, for its creator, Dr. Felix Wankel. It has been popular at various times in sports cars because of the power it can produce. The rotary engine delivers more power than a piston engine. Although it has fewer moving parts, and should be more reliable by design, the parts are prone to breakage and failure.
Overview
Combustion engines combine air and fuel and burn them to produce pressure. In a piston engine, the pressure in the cylinders forces the pistons to move; the crankshaft converts this movement into rotational movement, which can be used to power a vehicle. Instead of pistons, a rotary engine uses a curved equilateral triangle–shaped rotor inside of a housing. As the rotor moves, the faces of the triangle create chambers within the housing. The gas and air mixture in these chambers ignites and then expands and contracts as the rotor moves, providing multiple effects at once: intake, compression, combustion, and exhaust. The combustion pressure in these chambers powers the movement of the vehicle. A rotary engine has multiple rotors; three or five are standard.
German engineer Wankel developed the idea for the rotary engine in 1924, when he was seventeen years old. He set up a workshop and began refining the ideas for an engine that would rotate and simultaneously achieve the four important functions of a combustion engine. He developed his rotary valves and used these ideas during World War II (1939–1945) when he worked for the German Aeronautical Research Establishment developing aircraft engines. During the 1950s, he worked for a German car and motorcycle manufacturer, NSU Motorenwerke AG, where he finished developing the rotary-piston engine in 1954. It was tested three years later.
Bringing the engine to the market took many more years. Automakers competed to gain access to NSU's lightweight, smooth-running unit. Its simplicity in comparison to piston engines meant that it cost less to manufacture. It was not the only rotary engine being developed at the time, but the executives at Mazda were intrigued by Wankel's design. Mazda, which was working to become a global automaker, won the contract and began developing the rotary engine for use in vehicles. The company had to overcome some flaws, such as wear marks that quickly appeared within the rotary housing and seals on the three corners of the rotors that wore out quickly. Forty-seven engineers spent several years perfecting the design. The first dual-rotor rotary engine car, the Cosmo Sport, debuted in 1967. Mazda sports cars quickly drew fans worldwide. Other motor companies—including General Motors, Suzuki, and Toyota—also licensed the Wankel design, but Mazda sports cars became synonymous with the rotary engine.
Rotary engines have some significant drawbacks. The large combustion chamber burns more fuel, and vehicles tend to get low mileage per gallon. This produces significant carbon dioxide emissions. The engines are sometimes unreliable and produce low torque, or the engine's turning ability, which affects acceleration. During the early twenty-first century, however, Mazda developed a car powered by a hydrogen rotary engine. The company was also developing electric cars using rotary engines. The first model debuted in 2013.
Bibliography
"Chapter 1: Opening a New Frontier with the Rotary Engine." Mazda, www.mazda.com/en/innovation/stories/rotary/newfrontier/. Accessed 2 Oct. 2017.
"Chapter 3: Entering a New Era and Looking Further into the Future." Mazda, www.mazda.com/en/innovation/stories/rotary/newera/. Accessed 2 Oct. 2017.
"Engineering Explained: The Pros and Cons of Inline 5s, V10s and Rotary Engines." Car Throttle, 2014, www.carthrottle.com/post/engineering-explained-the-pros-and-cons-of-inline-5s-v10s-and-rotary-engines/. Accessed 2 Oct. 2017.
Fowler, Glenn. "Felix Wankel, Inventor, Is Dead; Creator of Rotary Engine Was 86." New York Times, 14 Oct. 1988, www.nytimes.com/1988/10/14/obituaries/felix-wankel-inventor-is-dead-creator-of-rotary-engine-was-86.html. Accessed 2 Oct. 2017.
Lewis, Owen (Quora). "Why Mazda's Rotary Automobile Engine Never Became Widely Popular." Forbes, 11 Apr. 2017, www.forbes.com/sites/quora/2017/04/11/why-mazdas-rotary-automobile-engine-never-became-widely-popular/#72f72ed43c79. Accessed 2 Oct. 2017.
Nice, Karim. "How Rotary Engines Work." HowStuffWorks, 29 Mar. 2001, auto.howstuffworks.com/rotary-engine.htm. Accessed 2 Oct. 2017.
"1902: Rotary Engine Inventor Felix Wankel Born." History.com, 2009, www.history.com/this-day-in-history/rotary-engine-inventor-felix-wankel-born. Accessed 2 Oct. 2017.
Rong, Blake Z. "12-Rotor Wankel Engine Will Melt Your Brain." Autoweek, 24 Feb. 2014, autoweek.com/article/car-life/12-rotor-wankel-engine-will-melt-your-brain. Accessed 2 Oct. 2017.
Russ, Carey. "The Wankel Engine History." The Auto Channel, 2004, www.theautochannel.com/news/2004/07/04/202357.html. Accessed 2 Oct. 2017.
Stecher, Nicolas. "Mazda's Confusing Plan to Resurrect the Famously Dirty Rotary Engine." Wired, 1 Dec. 2015, www.wired.com/2015/12/mazdas-confusing-plan-to-resurrect-the-famously-dirty-rotary-engine/. Accessed 28 Sept. 2017.
Webster, Larry. "How It Works: The Mazda Wankel Rotary Engine." Popular Mechanics, 1 Sept. 2011, www.popularmechanics.com/cars/a7103/how-it-works-the-mazda-rotary-engine-with-video/. Accessed 2 Oct. 2017.