Kazuaki Shiinoki

Development of Torque Fluctuation Reducer made of Permanent Magnets for Screw Compressors

We developed a torque-fluctuation reducer, which can almost completely cancel a screw compressors torque-fluctuation and reduce its vibration and noise. The device consists of inner and outer rings. Each ring has eight pairs of permanent-magnets arranged in a circle-one S-and-N pole pair for each of the male rotors lobes. The inner ring is fixed to the male rotor shaft, and the outer ring is fixed to the casing. Turning of the inner ring, produces magnetic forces, which in turn cause sinusoidal torque fluctuations. We tuned the reducer for a 7.5 kW oil-injected air screw compressor. With the best match, the male rotors rotational vibration decreases to less than 10% of its original. The level of noise due to meshing frequency decreases to 5 dB (A) at 1 m from the front of the compressor package.