| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent a liquid return without causing an abnormal stop of a compressor. SOLUTION: When a cooling operation is re-started after a defrosting operation is completed, a pump-down solenoid valve is opened and, after 20 seconds, the compressor is driven and then a pre-cooling operation is performed over one minute and thirty seconds. Thirty seconds after the start of the pre-cooling operation, the solenoid valve is closed for thirty seconds, and then the solenoid valve is re-opened. Since the solenoid valve is closed for thirty seconds, the circulation of a refrigerant to a cooler is stopped to prevent the liquid return. When the solenoid valve is closed, a low pressure in a refrigerating circuit is lowered. However, since the timing of closing the solenoid valve is brought to the peak of the lower pressure when the low pressure is raised again after being temporarily lowered during the pre-cooling operation, though the low pressure is lowered as shown by a characteristic line P, its pressure value is not excessively lowered, and does not lead to an abnormal stop of the compressor by the operation of a pressure switch. COPYRIGHT: (C)2005,JPO&NCIPI
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