Currently available air motors have many advantages over electric motors. They are more compact, lighter-weight, instantly reversible without sparking, create no heat buildup, are undamaged by stalling or overloading, and supply extremely broad torque and speed range. Generally available commercial air motors, however, have only 5% to 20% of ideal efficiency.
The Harmonic Air Motor developed at Lawrence Livermore National Laboratory, Livermore, CA, has all these advantages of air motors, as well as more than 60% of ideal efficiency, higher low-end torque than available commercial air motors, and can be manufactured at lower cost. It uses reed valves, and has a structure nearly identical to conventional, mass-produced, oil-free air compressors. As a result, it can be manufactured inexpensively and with minimal changes to existing production designs.
The motor can use compressed air at pressures of 80 to 100 psig, widely available in plants or at remote job sites, and is capable of up to 200 psig operation for higher power. It consumes 10% to 30% as much compressed air as conventional air motors for equivalent power. The oil-free design enables use of exhaust air for cooling or AC purposes, and eliminates the need for oil lubrication over its lifetime. The Harmonic Air Motor also features an automatic speed governor to prevent runaway, and is compatible with saturated or superheated steam operation.
Applications include hoisting operations that benefit from the simple speed control of the Harmonic Air Motor, and also from the ease of reversing, which permits accurate control of lifting, lowering, and itinerant. It can be used for direct-drive vehicular propulsion, thus eliminating the need for a transmission. In conjunction with a compressed air storage reservoir, the Harmonic Air Motor, by virtue of its high efficiency, is a viable approach to the storage and recovery of energy originating from intermittent renewable energy sources such as wind or solar.