Wankel engine

The Wankel rotary engine is a type of internal combustion engine, invented by German engineer Felix Wankel, which uses a rotor instead of reciprocating pistons. This design promises smooth high-rpm power from a compact, lightweight engine; however Wankel engines are criticized for poor fuel efficiency and exhaust emissions.

History

Wankel first conceived his rotary engine in 1924 and finally received a patent for it in 1929. He worked through the 1940s to improve the design. Considerable effort went into designing rotary engines in the 1950s and 1960s. They were of particular interest because they were smooth and very quiet running, and the reliability resulting from their simplicity.

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In Britain, Norton Motorcycles developed a Wankel rotary engine for motorcycles, which was included in their Commander; Suzuki also produced a production motorcycle with a Wankel engine, the RE-5. John Deere Inc, in the US, had a major research effort in rotary engines and designed a version which was capable of using a variety of fuels without changing the engine. The design was proposed as the power source for several US Marine combat vehicles in the late 1980s.

Related Topics:
Norton Motorcycles - Motorcycle - Commander - Suzuki - John Deere - US Marine

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After occasional use in automobiles, for instance by NSU with their Ro 80 model, Citroën with the M35 and GS Birotor using engines produced by Comotor, and abortive attempts by General Motors and Mercedes Benz to design Wankel-engine automobiles, the most extensive automotive use of the Wankel engine has been by the Japanese company Mazda.

Related Topics:
NSU - Ro 80 - Citroën - M35 - GS - Comotor - General Motors - Mercedes Benz - Automobile - Japan - Mazda

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After years of development, Mazda's first Wankel engined car was the 1967 Mazda Cosmo. The company followed with a number of Wankel ("rotary" in the company's terminology) vehicles, including a bus and a pickup truck. Customers generally loved them, notably the smoothness. However they had the very bad luck of being released in the middle of efforts to decrease emissions and increase fuel economy. Mazda later abandoned the Wankel in most of their automotive designs, but continued using it in their RX-7 sports car until August of 2002 (although RX-7 importation for North America ceased with the 1995 model year). The company normally used two-rotor designs, but received considerable attention with their 1991 Eunos Cosmo, which used a twin-turbo three-rotor engine. In 2003, Mazda re-launched the rotary with the new RX-8. This new engine relocated the ports for exhaust and intake from the peripheral of the rotary housing to the sides, allowing for larger overall ports, better airflow, and further power gains. The renesis is capable of delivering 238 horsepower from its minute 1.3 liter displacement at better fuel economy, reliability, and environmental friendliness than any other Mazda rotary engine in history.

Related Topics:
Mazda - Wankel engined - Mazda Cosmo - Pickup truck - RX-7 - Sports car - August - 2002 - Eunos Cosmo - Turbo - 2003 - RX-8

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The Malibu Grand Prix chain, similar in concept to commercial recreational kart racing tracks, operates several venues in the United States where a customer can purchase several laps around a track in a vehicle very similar to open wheel racing vehicles, but powered by a small Curtiss-Wright rotary engine.

Related Topics:
Malibu Grand Prix - Kart racing - United States - Open wheel racing - Curtiss-Wright

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Although VAZ, the Soviet automobile manufacturer, is known to have produced Wankel-engine automobiles, and Aviadvigatel, the Soviet aircraft engine design bureau, is known to have produced Wankel engines for aircraft and helicopters, little specific information has surfaced in the outside world; what has been seen indicates a general similarity to Wankel designs by NSU, Comotor, and Mazda, therefore it is likely that many Western patents were infringed upon by these designs, the probable reason for their being hidden.

Related Topics:
VAZ - Soviet - Aviadvigatel - NSU - Comotor - Mazda - Patent

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The People's Republic of China is also known to have experimented with Wankel engines, but even less is known in the West about the work done there, other than one paper, #880628, delivered to the SAE in 1988 by Chen Teluan of the South China Institute of Technology at Guangzhou.

Related Topics:
People's Republic of China - SAE - Chen Teluan - South China Institute of Technology - Guangzhou

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Automobile racing

In the racing world, Mazda has had substantial success with two-rotor, three-rotor, and four-rotor cars, and private racers have also had considerable success with stock and modified Mazda Wankel-engine cars.

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The Sigma MC74 powered by a Mazda 12A engine was the first engine and team from outside Western Europe or the United States to finish the entire 24 hours of the 24 Hours of Le Mans race, in 1974. Mazda is the only team from outside Western Europe or the United States to have won Le Mans outright and the only non-piston engine ever to win Le Mans, which the company accomplished in 1991 with their four-rotor 787B (2622 cc actual displacement, rated by FIA formula at 4708 cc). Mazda is also the most reliable finisher at LeMans (with the exception of Honda, who have entered only three cars in only one year), with 67% of entries finishing.

Related Topics:
Western Europe - United States - 24 Hours of Le Mans - Race - 787B - Displacement - Honda

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The Mazda RX-7 has won more IMSA races in its class than any other model of automobile, with its one hundredth victory on September 2, 1990. Following that, the RX-7 won its class in the IMSA 24 hours of Daytona race ten years in a row, starting in 1982. The RX7 won the IMSA Grand Touring Under Two Liter (GTU) championship each year from 1980 through 1987, inclusive.

Related Topics:
Mazda RX-7 - IMSA - September 2 - 1990 - 24 hours of Daytona

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Formula Mazda Racing features open-wheel race cars with Mazda Wankel engines, adaptable to both oval tracks and road courses, on several levels of competition. Since 1991, the professionally organized Star Mazda Series has been the most popular format for sponsors, spectators, and upward bound drivers. The engines are all built by one engine builder, certified to produce the prescribed power, and sealed to discourage tampering. They are in a relatively mild state of racing tune, so that they are extremely reliable and can go years between motor rebuilds.http://www.starmazda.com/index.html

Related Topics:
Formula Mazda Racing - Star Mazda Series

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Aircraft engines

The Wankel's superb power-to-weight ratio, reliability, and small frontal area make it particularly well suited to aircraft engine use. There was intense interest in them in this role in the 1950s when the design was first becoming well known, but it was at this same time that almost the entire industry was moving to the jet engine, which many believed would be the only engine in use within a decade. The Wankel suffered from a lack of interest, and when it later became clear that the jet engine was far too expensive for all roles, the general aviation world had already shrunk so much that there was little money for new engine designs. Nevertheless, interest in them for small aircraft has continued.

Related Topics:
Power-to-weight ratio - Aircraft engine - Jet engine - General aviation

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The first rotary-engine aircraft was the experimental Lockheed Q-Star civilian version of the U.S. Army's reconnaissance QT-2, basically a powered Schweizer sailplane, in 1968 or 1969. It was powered by a 185 horsepower (138 kW) Curtiss-Wright RC2-60 Wankel rotary engine.

Related Topics:
Lockheed - U.S. Army - Schweizer - Sailplane - Curtiss-Wright

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Aircraft Wankels have made something of a comeback in recent years. None of their advantages have been lost in comparison to other engines, and the introduction of better materials has helped the tip-seal (Apex-seal) problem. They are being found increasingly in roles where their compact size and quiet running is important, notably in drones, or UAVs. Many companies and hobbyists adapt Mazda rotary engines to aircraft use; others, including Wankel GmbH itself, manufacture Wankel rotary engines dedicated for the purpose.

Related Topics:
UAV - Wankel GmbH

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Other uses

Small Wankel engines are being found increasingly in other roles, such as go-karts, personal water craft and auxiliary power units for aircraft. The Graupner/O.S. 49-PI is a 1.27 horsepower (947 W) 5 cc Wankel engine for model airplane use which has been in production essentially unchanged since 1970; even with a large muffler, the entire package weighs only 13.4 ounces (380 grams).

Related Topics:
Go-karts - Personal water craft - Auxiliary power unit - Graupner - Model airplane

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The simplicity of the Wankel makes it ideal for mini, micro, and micro-mini engine designs. The MicroElectroMechanical Systems (MEMS) Rotary Engine Lab at the University of California, Berkeley has been developing Wankel engines of down to 1 mm in diameter with displacements less than 0.1 cm³. Materials include silicon and motive power includes compressed air. The goal is to eventually develop an internal combustion engine that will deliver 100 milliwatts of electrical power; the engine itself will serve as the rotor of the generator, with magnets built into the engine rotor itself.

Related Topics:
MEMS - University of California, Berkeley - Generator - Magnet

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The largest Wankel engine was built by Ingersoll-Rand; available in 550 horsepower (410 kW) one rotor and 1100 horsepower (820 kW) two rotor versions, displacing 41 liters per rotor with a rotor approximately one meter in diameter, it was available between 1975 and 1985. It was derived from a previous, unsuccessful, Curtiss-Wright design, which failed because of a well-known problem with all internal combustion engines; the fixed speed at which the flame front travels limits the distance combustion can travel from the point of ignition in a given time, and thereby the maximum size of the cylinder or rotor chamber which can be used. This problem was solved by limiting the engine speed to only 1200 rpm and use of natural gas as fuel; this was particularly well chosen, as one of the major uses of the engine was to drive pumps on natural gas pipelines.

Related Topics:
Ingersoll-Rand - 1975 - 1985 - Curtiss-Wright - Internal combustion engine - Flame front - Natural gas - Pipeline

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Aside from being used for internal combustion engines, the basic Wankel design has also been utilized for air compressors, and superchargers for internal combustion engines, but in these cases, although the design still offers advantages in reliability, the basic advantages of the Wankel in size and weight over the four-stroke internal combustion engine are irrelevant. In a design using a Wankel supercharger on a Wankel engine, the supercharger is twice the size of the engine!

Related Topics:
Air compressor - Supercharger

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Perhaps the most exotic use of the Wankel design is in the seat belt pretensioner system of the Volkswagen New Beetle. In this car, when deceleration sensors sense a potential crash, small explosive cartridges are triggered electrically and the resulting pressurized gas feeds into tiny Wankel engines which rotate to take up the slack in the seat belt systems, anchoring the driver and passengers firmly in the seat before any collision.

Related Topics:
Seat belt - Volkswagen - New Beetle - Deceleration - Sensor

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