| 摘要 |
PURPOSE:To reduce the difference between the discharge pressure and suction pressure of the compressor and consequently reduce the noise emitted at balancing of the pressures by a method wherein the output frequency of the inverter is lowered for a fixed period of time before the change-over from the heating operation to the defrosting operation of heat pump. CONSTITUTION:The heat pump 1 consists of the compressor 2, a four-way valve 3, an indoor side heat exchanger 4, a throttling device 5 and an outdoor side heat exchanger 6, all of which are connected by means of piping with one another. In the heat pump 1, the rotational frequency of the compressor 2 is controlled by changing the output frequency of the inverter 7. When a defrosting signal is generated in said heat pump 1 controlled with the inverter 7, the time is counted from the time T0 when the defrosting signal is detected and when the time attains to the time T1, which is several minutes before the time T2 for starting the defrosting operation, the output frequency of the inverter 7 is lowered. As a result, the difference between the discharge pressure and the suction pressure of the compressor 1 is turned to be smaller as compared with the pressure difference which had during the interval of time from T0 to T1. After the elapse of time T2 from the time T0, the heat pump 1 is changed-over from the heating operation to the defrosting operation. |
