Means for producing an optimized cooler expander waveform

摘要

A means for producing an optimized cooler expander waveform for a closed cycle cryogenic cooler. The cooler displacer is driven by magnetic and spring biasing means through four repeated phases of each cycle to produce four portions of the optimized cooler waveform in which each portion takes up about 25% of the total cycle. The portions are comprised of a constant velocity in opposite direction and dwell times with smoothed corner transitions between each portion. Control means for controlling the displacer movement to produce the specific waveform may be provided by a function generator applying the desired waveform into a displacer control drive circuit which has as a second input a sensory signal of the actual position of the displacer. The actual position and the desired position are continuously compared while the drive circuit drives two opposing solenoids during the constant velocity phases of the displacer movement with two spring biasing means holding the displacer during the dwell times at the end of each stroke.