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Air-conditioning apparatus

  • US 9,976,766 B2
  • Filed: 04/26/2012
  • Issued: 05/22/2018
  • Est. Priority Date: 04/26/2012
  • Status: Active Grant
First Claim
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1. An air-conditioning apparatus in which at least one load side unit including a load side heat exchanger is connected to a heat source side unit including a compressor, a heat source side heat exchanger, and an expansion device, and a refrigerant is circulated between the units to form a refrigeration cycle, the apparatus comprising:

  • a controller configured toestimate a time constant of a control value at a time when an opening degree of the expansion device is changed, the control value is at least one of a degree of superheat at a suction side of the compressor, a temperature of the refrigerant at a discharge side of the compressor, and a degree of subcooling at an outlet side of the heat source side heat exchanger which is serving as a condenser,calculate at least one of a control gain of the opening degree of the expansion device and a control interval of the expansion device on the basis of the control value;

    change the control gain or the control interval on the basis of the calculated at least one of the control gain and the control interval, andchange the opening degree of the expansion device on the basis of the changed at least one of the control gain and the control interval,wherein the time constant is estimated using a relationship that a parameter=(control interval/control gain ratio)/(time constant+dead time), whereinthe parameter is a dimensionless parameter with which a settling time is minimum,the settling time is a time for the control value to be in a predetermined range from a control target value,the gain ratio is a value obtained by dividing the control gain by a response gain of the control value in order to cause the control gain to be a control target gain value by an operation performed once, andthe dead time is a time from a time when an opening degree change order is issued to the expansion device to a time when a change appears in the control value.

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