Engineers at Air Squared Inc., Broomfield, Colo. (www.airsquared.com), have developed the world’s smallest continuous-duty, oil-free scroll compressor, according to the company. It delivers 48% efficiency to meet the application requirements of lightweight, battery-powered, low-noise devices, such as medical equipment, electronics, and aerospace and military gear. Inherently vibration-free, the orbiting scroll puts out 5 lpm of pulse-free flow at up to 7-psig discharge pressure. The new design eliminates the need for a dynamic seal by using a traditional orbiting scroll rather than a spinning scroll. Many parts in the compressor can be injection molded to minimize the size and weight of components. The compressor can also be scaled up, according to the manufacturer.
The compressor uses two identical involutes, which form right and left-hand components. One scroll is indexed or phased 180° with respect to the other so the two mesh. This indexing creates crescent-shaped gas pockets bounded by the involutes and base plates of both scrolls. In operation, one scroll remains fixed while the other turns because it attaches to an eccentric driven by the motor shaft. As the moving scroll orbits the fixed scroll, gas pockets follow the spiral inward and get smaller, thus compressing air. The compressed air gets discharged through an outlet in the center of the scrolls. When run in reverse, the compressor can be used as an expander or air motor.