The Di Pietro Motor (Rotary Air Engine)
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 shaft driver is divided in 6 expansion chambers by pivoting dividers. These dividers follow the motion of the shaft driver as it rolls around the stator wall. The motor shown is effectively a 6 cylinder expansion motor.


How it Works

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 film of air. Timing and duration of the air inlet and exhaust is governed by a slotted timer which is mounted on the output shaft and rotates at 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 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 volume 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.

Angelo Di Pietro Director of R & D said:
"There is no other motor as good as ours, the invention has a long list of important improvements over other motors, with the efficiency being several times better then our competitors.”

We have verification of its performance

  • Outstanding efficiency up to 94.5%
  • Constant high torque
  • Low parts count
  • Low number of moving parts
  • Virtually no friction
  • Smooth speed control characteristics
  • Compact and light
  • No vibration
  • Only 1 PSI of pressure is needed to overcome the friction