| 摘要 |
A centrifugal compressor (20) is preceded by adjustable pre-rotation vanes (31) and is driven by a variable-speed motor (36). The compressor (20), a condenser (22) and an evaporator (28) are connected in a closed refrigeration circuit. The control device includes a circuit (56, 58, 59) for supplying a signal which varies as the ratio between the output and intake pressures of the compressor, and a device (44, 37) for using the signal indicating the ratio between output and intake pressures of the compressor to adjust the speed of the electric drive motor, so that a combined control of the speed of the drive motor and of the adjustable control device is produced so as to save energy and without stalling the compressor. <IMAGE>
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