September 15, 2004 There is no other motor as efficient as the Di Pietro Rotary Air Engine. It is 100% more efficient than any other air powered engine built to date and its high torque makes it the first air engine suitable for mobile applications. The invention has the capacity to revolutionise transportation, plus offer a multitude of energy-saving benefits in stationary applications.

The engine has no emissions, is very quiet, has constant high torque, a low parts count, no vibration and is very efficient - only 1 PSI of pressure is needed to overcome the friction to enable movement.

The engine has no emissions, is very quiet, has constant high torque, a low parts count, no vibration and is very efficient - only 1 PSI of pressure is needed to overcome the friction to enable movement.

Former Mercedes Benz experimental engineer Angelo di Pietro conceived the Rotary Air Engine while working in his Melbourne-based Engineering business over many years.

"I started work on this project many years ago in my head," said Pietro, "and I have seen the need for such an engine many times. As my engineering business was doing okay, I was able to spend more time on the idea and with each new prototype the design has been refined."

In 1999 he made a major design breakthrough and the first prototype was constructed. Since then, six prototypes have been built, each more efficient, more powerful and lighter than the previous one.

It's not surprising that Di Pietro's design should be a rotary engine. Angelo Di Pietro, (1950, Avellino, Italy) qualified as Congegniatore Meccanico in Avellino moved to Stuttgart, Germany to work on the Wankel rotary engine at the Mercedes Benz research laboratories 1969 and 1970. In 1971 he migrated to Australia where he established a construction engineering company.

From his early experience with Wankel rotary engines, Angelo became interested in developing a more efficient engine than the traditional reciprocating internal combustion engine, and he has worked on various alternative concepts intermittently over the last 30 years.

Recognising the potential of his invention Di Pietro decided to fully focus on the development of the new motor concept. The principle worked with the first prototype and, although not built to fine engineering tolerances, its performance far exceeded expectations.

Engineair Pty Ltd ( was established in September 2000, with the objective to perform research and development on the innovative air motor design. In the first 2 years the company focused on developing prototype models to test the concept and understand the performance characteristics. Current development status shows performance and efficiency to be superior over state of the art air motor technology.

Engineair is now entering the commercialisation of its technology and is working on several fronts to prove the engine's capability. One of the first commercial applications will see the Engineair Rotary Air Engine applied in a commercial and outdoor environment by Melbourne-based CityWide which has replaced the petrol driven engine in one of its ParkCare garden maintenance vehicles (known as a 'gator').

The vehicle will be used on the company's City of Melbourne parks and garden maintenance contract. The project will run over 2004-05 enabling CityWide to test the vehicle under different environmental conditions.

Engineair has already successfully tested the powerplant in a roadgoing passenger car, a go-kart, a boat and as the power source for a utility vehicle for use in the Melbourne Fruit and Vegetable market, the latter project in conjunction with the Melbourne Market Authority.

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.

The space between stator and rotor is divided into six expansion chambers by pivoting dividers. These dividers follow the motion of the shaft driver as it rolls around the stator wall.

The cylindrical shaft driver, forced by the air pressure on its outer wall, moves eccentrically, thereby driving the motor shaft by means of two rolling elements mounted on bearings on the shaft.

The rolling motion of the shaft driver inside the stator is cushioned by a thin air film. Timing and duration of the air inlet and exhaust is governed by a slotted timer which is mounted on the output shaft and rotates with the same speed as the motor.

Variation of performance parameters of the motor is easily achieved by varying the time during which the air is allowed to enter the chamber: A longer air inlet period allows more air to flow into the chamber at high pressure and therefore results in more torque.

A shorter inlet period will limit the air supply and allows the air in the chamber to perform expansion work at a much higher efficiency. In this way compressed air (energy) consumption can be exchanged for higher torque and power output depending on the requirements of the application.

Motor speed and torque are simply controlled by throttling the amount or pressure of air into the motor. The Di Pietro motor gives instant torque at zero RPM and can be precisely controlled to give soft start and acceleration control.

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