| 摘要 |
PURPOSE:To judge rapidly the finish of defrosting and reduce electric power consumption by providing variable speed means which controls the rotational seed of a compressor in variable speeds according to a set value and rotational speed setting means which, during defrosting operation, switches the set value of the rotational speed of the compressor based on certain conditions. CONSTITUTION:When frost accumulates on a heat exchanger 5 on the outdoor side and the heat exchanger enters defrosting operation, a solenoid valve 8 opens and at the same time the rotational speed of a compressor 1 is raised to f1 by an inverter 9 and high temperature and high pressure coolant which is discharged from the compressor 1 flows into the heat exchanger 5 on the outdoor side from a gas bypass pipe 7 to start melting the frost. And the temperature of the piping TA is detected by a thermistor 10 and the temperature is compared with a set temperature TO by a defrosting finish judgement device 11 and on the other hand the time that has passed since starting the defrosting is counted by an arithmetic unit 13, and when a time t1 has passed, rotational speed setting means 15 lowers the rotational speed of the compressor 1 to f2(f2<f1) regardless of the defrosting finish judgement by means of an inverter 9. Then, for TA>TO the rotational speed setting means 15 sets the rotational speed of the compressor 1 to f4 and closes the solenoid 8 by drive means 14 and finishes the defrosting operation.
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