Wankel engine: construction/cars/Mazda designs | autozeitung.de

When the first car with a Wankel engine was presented in 1963, Felix Wankel was not the only one who believed that the principle named after him would replace the reciprocating engine. But after a successful start, the triangular pistons spinning happily disappeared from the engine rooms again, with few exceptions.

How does a Wankel engine work?

The principle of the Wankel engine: The piston (in this case it is called a disk) is not driven up and down constantly, but in the movement of water in a circle. The combustion chamber is reminiscent of two circles that join the disc (piston) reminiscent of a triangle with rounded sides. In fact, the “Wankel engine” file seemed to be already closed when the Mazda RX-8 sports car was the last rotary piston car to slowly disappear from the world market in the 2010s – including Germany. But in 2023 it was the Wankel guardians from Hiroshima who brought the rotary pistol back to life.

The single-disc Wankel will be used in the Mazda MX-30 e-Skyactiv R-EV, which will be presented in 2023, as it was in the first car with a Wankel engine. But unlike the chic, small, rear-engine NSU/Wankel Spider roadster from 1963, the rotary piston engine in the MX-30 R-EV is responsible for generating electricity on board in cooperation with the generator. Due to the change in mobility, the actual wheeled vehicle is powered by an electric motor. Also interesting: Tips for our products on Amazon

The Mazda MX-30 R-EV (2023) im Video:

Introduction to the Wankel engine

In 1963, electric cars were not an issue. The NSU/Wankel Spider played the role of a “game changer” during its presentation at the IAA in Frankfurt. As early as 1957, Felix Wankel (the name of the Wankel engine) and NSU presented a complex rotary piston engine, in which not only a triangular piston but also a housing rotates around it. In practical implementation – and initially rather to the annoyance of its inventor – this led to a simple rotary piston engine, which met with great interest among car manufacturers.

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What are the advantages of the Wankel engine?

The advantages of the Wankel engine concept over the reciprocating piston engine were obvious: very few moving parts, no constantly rotating crosspieces such as up and down pistons or flapping valves and therefore no constantly changing load direction. Instead, the rotational motion of the low-vibration triangle piston has one cycle of work per piston revolution, whereas a single-cylinder piston engine only produces power every second revolution (“load cycle”).

The NSU Ro 80 gets the Wankel engine moving

NSU didn’t necessarily do much business with the Wankel Spider, which was introduced in 1963 and sold just 2,375 by 1967, but that would change from 1967 onward. Then the company from Neckarsulm launched its NSU Ro 80 at the IAA in Frankfurt, where the spacious sedan had not only a rotary engine of 115 hp (85 kW), but also a futuristic body design (cd value: 0, 35 – sensational) be pleased. But soon the big NSU fell into disrepute among customers due to frequent engine damage, accompanied by high consumption of oil and fuel. After all, an incredible 37,374 Ro 80s were built until 1977, before the NSU brand ended up in the Volkswagen Group at Audi. At Wankel they made it into an Audi 100 model (C2 series), but it was not heard again until the Audi A1 e-tron from 2010 – an electric study with a Wankel engine as a range extension.

Wankel engine tests at Mercedes

Mercedes also actively researched and developed the Wankel engine, and not just in secret. For this purpose, the car manufacturer from Swabia used the research car C 111, a previously unknown car, a 1.1 m flat super sports car that was often shown at trade fairs – including Geneva in 1970, where the second generation of the C 111 with a 350 hp (257 kW) Wankel Engine (four times 602 cm).³ chamber volume) celebrated its premiere. But not in the C 111 or any other Mercedes did the rotary piston engine go into series production. The oil crisis also contributed to this. The Wankel engine, which was not particularly economical due to its principle, was not an effective antidote to the rise in fuel prices in 1973. Its angled combustion chamber geometry compared to a reciprocating piston engine and its large surface area relative to much of it stood in the way of efficient, low-emission combustion.

The first rotary engines at Mazda

Although several other manufacturers such as GM (Corvette research), Lada and Citroën researched the principle, for a long time there was only one manufacturer that relied on the rotary engine: Mazda. Mazda was one of the first car companies to sign a license agreement with NSU in 1961 for the development and construction of rotary piston engines. The Japanese brand showed the first prototype in the same year, and this marked the beginning of the race for the first Wankel production car, which NSU won with the Wankel Spider. But instead of a single disc Wankel as in the NSU Spider, Mazda chose a more powerful engine with two rotating triangular pistons: the Mazda Cosmo Sport 110 S sports car was born. Many other designs followed with shorter, lighter and more modern piston pistons, many bearing the RX abbreviation in the logo. In Germany, however, they were usually not highly regarded or even sold.

The Mazda RX-7 and RX-8 make the rotary engine essential in Germany

In Germany, the Wankel engine returned to the conversation with the first series Mazda RX-7, introduced in 1978. The RX-7 really became popular in the United States, where it was seen as a cheaper alternative to the Porsche 924 and 944 models. Two more generations of the RX-7 followed, including the convertible (second generation), and the third generation with a 240 hp (177 kW) biturbo rotary piston engine. By 2002, more than 811,000 units of the Mazda RX-7 had been sold worldwide. This makes the Mazda RX-7 the best-selling car with a rotary engine overall.

With the Mazda RX-8, the last chapter in the history of the Wankel engine was opened in Japan in 2003. As 2+2 seats and rear doors that open at the rear, the RX-8 was given a little everyday practicality. Under the flat hood was a brand new Wankel twin disc engine from the Renesis generation with 192 or 231 hp (141 or 170 kW). One of the most important innovations was the transfer of the exhaust channels to the side wall of the rotor housing, which resulted in more efficient compression and thus lower consumption. But the RX-8 was no slouch when it came to car fuel either, and you had to make sure the fuel level was adequate.

Wankel engine at the moment

After the RX-8 became history, only the Mazda MX-30 e-Skyactiv R-EV brought back the Wankel engine as a range extender. Mazda Iconic SP sports car research also works according to this principle. Because the single disc Wankel engine is not only responsible for the car, but also provides electricity to the electric motor, the compact unit can work under optimal conditions of load and speed and is therefore very economical. What remains is the unique sound that the rotary piston creates.

The idea of ​​powering an electric car using a Wankel engine was also taken up in 2010 with the Audi A1 e-tron. There may be more then, which was also confirmed in the first test drives. But Wankel’s approach to the Audi A1 e-tron could not be reconciled with the Group’s electric strategy from Wolfsburg at the time. And so the continuation of Wankel’s history will continue to depend on the Mazda manufacturers in Hiroshima.