| 摘要 |
PURPOSE:To prevent a sudden pressure rise in a high pressure side and avoid useless operation shutdown by switching over a main indoor heat exchanger to an auxiliary outdoor heat exchanger when the high pressure-side pressure of a freezing cycle is below a predetermined value and slowing down the change speed of operation frequency of a compressor compared with ordinal operation when the main outdoor heat exchanger is operated. CONSTITUTION:When a condensation pressure becomes below a preset value, a main heat exchanger operation pattern which uses a main outdoor heat exchanger 5 is changed over to an auxiliary heat exchanger operation pattern which uses an auxiliary heat exchanger 12. In other words, a two way valve 4 of an outdoor unit A is closed and two way valves 10 and 11 are opened while a two way valve 13 is closed. The refrigerant discharged from a compressor 1 flows to the auxiliary outdoor heat exchanger 12 by way of the two way valve 11. When an operation frequency command of a branch control section is moved to a rising direction, the operation frequency of the compressor 1 is set to move at a slower speed than the speed during the ordinal operation when the main outdoor heat exchanger 5 is operated. This construction makes it possible to increase a higher pressure side pressure gradually and prevent a drastic rise in the pressure by slowing down the speed so that a high pressure switch Pdsw for protection may not operate. |
