| 摘要 |
PURPOSE:To contrive protection of a compressor, by a method wherein a compressor is sufficiently lubricated in a transfer period through utilizing the fact that the compressor is transferred from one rotating speed range other than a normal rotating speed range to another such rotating speed range through the normal rotating speed range at the time of starting the compressor or when air conditioning load is largely varied. CONSTITUTION:At the time of starting, the rotating speed of the compressor 1 is once raised to the maximum rotating speed, thereafter a blow-off temperature of a room-side heat exchanger 14 is detected by a temperature sensor 17, the detected temperature is compared with a room temperature set point by a frequency-setting unit 20, and a frequency-reducing command L according to the temperature difference is outputted from the unit 20 to a frequency-converting unit 21, whereby the rotating speed of the compressor 1 is reduced to a rotating speed not higher than the normal rotating speed range which speed corresponds to a low air conditioning load. Since the operating frequency M once enters a normal operating frequency range in the process of the reduction in the rotating speed of the compressor, the unit 20 continues transmitting a frequency-holding command X for a predetermined period of time to maintain an operating frequency in the normal operating frequency range for the period, and the compressor 1 is normally lubricated in this period, so that seizure is prevented from occurring.
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