A Compressed air engine is one that creates useful work by expanding compressed air. They have existed in many forms over the past two centuries, ranging in size from handheld turbines up to several hundred horsepower. Some types rely on pistons and cylinders, others use turbines. Many compressed air engines improve their performance by heating the incoming air, or the engine itself. Some took this a stage further and burnt fuel in the cylinder or turbine, forming a type of internal combustion engine.

Tools

Impact wrenches, drills, die grinders, dental drills and other pneumatic tools use a variety of air engines (or motors). These include vane type pumps, turbines and pistons.

Torpedoes

Most successful early forms of self propelled torpedoes used high pressure compressed air, although this was superseded by internal or external combustion engines, steam engines, or electric motors.

Railways

Compressed air engines were used in trams and shunters, and eventually found a successful niche in mining locomotives, although eventually they were replaced by electric trains, underground^[1]. Over the years designs increased in complexity, resulting in a triple expansion engine with air to air reheaters between each stage ^[2].

Aircraft

Transport category airplanes, such as commercial airliners, use compressed air starters to start the main engines. The air is supplied by the load compressor of the aircraft's auxiliary power unit, or by ground equipment.

Automotive

Main article: Compressed air vehicle

There is currently some interest in developing air cars. Several engines have been proposed for these, although none have demonstrated the performance and long life needed for personal transport.

Energine

The Energine Corporation is a South Korean company that delivers fully-assembled cars running on a hybrid compressed air and electric engine. The compressed-air engine is used to activate an alternator, which extends the autonomous operating capacity of the car.^[3]

EngineAir

EngineAir, an Australian company, is making a rotary engine powered by compressed air, called The Di Pietro motor. The Di Pietro motor concept is based on a rotary piston. Different from existing rotary engines, the Di Pietro motor uses a simple cylindrical rotary piston (shaft driver) which rolls, without any friction, inside the cylindrical stator. ^[4]

It can be used in boat, cars, carriers and other vehicles. Only 1 psi (≈ 6,8 kPa) of pressure is needed to overcome the friction. ^{[5] [6]}

K'Airmobiles

K'Airmobiles vehicle use a compressed-air engine known as the K'Air, developed in France by a small group of researchers

These engines have an consumption of compressed air of less than 120 L/min., although developing a dynamic push able to reach 4kN.

The technical concept of the K'Air pneumatic engines returns to direct conversion of what makes the fundamental characteristic of compressed air, namely:

• the pushing force of compressed air is exclusively exploited for conversion into kinetic energy of translation,
• itself is simultaneously converted into induced power of rotation of the axis and
• thus gives to the engine a particularly imposing torque while needing only a very low “fuel” consumption.

To simplify, one can compare the principle to that of the rotary jacks:

• the energy of the fluid (compressed air) is directly transformed into rotational movement;
• the double-acting jacks involve a pinion-toothed rack system;
• the cyclic angle of rotation can vary between 90 and 360°;
• it supports hydraulic supercharging systems.

MDI

Main article: Motor Development International

In MDI's original air engine, one piston compresses air from the atmosphere, holding it on a small container that feeds the high pressure air tanks with a small amount of air. Then that portion of the air is sent to the second piston where it works. During compression for heating it up, there is a loss of energy due to the fact that it cannot receive energy from the atmosphere as the atmosphere is less warm than it. Also, it has to expand as it has the crank. MDI's engine works with constant torque, and the only way to change the torque to the wheels is to use a pulley transmission of constant variation, losing some efficiency. When vehicle is stopped, MDI's engine had to be on and working, losing energy. In 2001-2004 MDI switched to a design similar to that described in Regusci's patents, which date back to 1990^[7].

Quasiturbine

Main article: Quasiturbine

The Pneumatic Quasiturbine engine is a compressed air pistonless rotary engine using a four-sided rhomboid rotor whose sides are hinged at the vertices.

The Quasiturbine has demonstrated as a pneumatic engine using stored compressed air ^[8].

It can also take advantage of the energy amplification possible from using available external heat, as the solar energy. ^[9]

The Quasiturbine rotates from pressure as low as 1/10 of atmosphere (bar).

Since the Quasiturbine is a pure expansion engine (which the Wankel is not, neither most of other rotary engines), it is well suitable as compressed fluid engine - Air engine or air motor. ^[10]

Regusci

Armando Regusci's version^[11] of the air engine couples the transmission system directly to the wheel, and has variable torque from zero to the maximum, enhancing efficiency. Regusci's patents date back to 1990^[12],

Team Psycho-Active

Psycho-Active is developing a multi-fuel/air-hybrid chassis which is intended to serve as the foundation for a line of automobiles. The chassis will achieve unprecedented performance, safety, flexibility, serviceability and economy.

This technology relies on a novel engine. The design is simple, adaptable and self starting. Designed to be efficient and low cost, it will be crafted to exhibit an extremely high power density^{[citation needed]}.

Karts

There are Karts with compressed air quasiturbine.^[13]

See also

• Angelo Di Pietro (inventor)
• Chopper (motorcycle)
• Compressed air energy storage
• Compressor
• Kit car

External links

• see TfDWikia has a wiki on this subject: cair
• Air engine at OScar
• Team Psycho-Active

References

1. Compressed-Air Propulsion
2. http://www.aircaraccess.com/images/3stage%201.jpg
3. Untitled Document
4. www.engineair.com.au
5. www.engineair.com.au
6. www.engineair.com.au
7. Armando
8. Quasiturbine Low RPM High Torque Pressure Driven Turbine for Top Efficiency Power Modulation. Peers reviewed paper - Published in The Proceeding of Turbo Expo 2007 of the IGTI (International Gas Turbine Institute) and ASME (American Society of Mechanical Engineers). Abstract and info
9. Quasiturbine> Type> Pneumatic
10. Quasiturbine> Type> Pneumatic
11. Motor
12. Armando
13. APUQ - Association de Promotion des Usages de la Quasiturbine

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Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Air engine". Image Credit.

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