Air-conditioning system

Abstract

An air-conditioning system capable of suppressing power consumption and maintaining the indoor temperature at a constant level includes a refrigerant circuit in which a compressor, a heat source-side heat exchanger, an expansion device, and a load-side heat exchanger are sequentially connected via a pipe, an inverter that drives the compressor, an indoor temperature sensor that detects an indoor temperature, and a controller that receives a thermostat ON signal and a thermostat OFF signal and controls the inverter according to the thermostat ON signal and the thermostat OFF signal. The controller assumes, upon receipt of the thermostat OFF signal, that the indoor temperature detected at that time is a target temperature, and regulates an output frequency of the inverter so as to maintain a difference between the indoor temperature and the target temperature in a predetermined range.

1 . An air-conditioning system comprising:
 a refrigerant circuit in which a compressor, a heat source-side heat exchanger, an expansion device, and a load-side heat exchanger are sequentially connected by piping;   an inverter configured to drive the compressor;   an indoor temperature sensor configured to detect an indoor temperature;   a controller configured to regulate an output frequency of the inverter to control the compressor in accordance with the indoor temperature detected by the indoor temperature sensor, and   a local thermostat configured to compare a temperature detected by the thermostat with a target temperature, and transmits a thermostat ON signal and a thermostat OFF signal to the controller,   wherein, during a first time point, the controller is configured to assume, upon receipt of the thermostat OFF signal from the local thermostat, that an indoor temperature detected by the indoor temperature sensor at a first time point when the thermostat OFF signal is received is the target temperature, and regulates the output frequency of the inverter so as to maintain a difference between the indoor temperature and the target temperature in a predetermined range, during the point between the first time point and a second time point, wherein the second time point is later than the first time point.   
     
     
         2 . The air-conditioning system of  claim 1 ,
 wherein the controller is configured to finish controlling the inverter regulated at the output frequency when the indoor temperature exceeds a permissible temperature difference from the target temperature, and turn off the compressor or cause the compressor to perform at a maximum frequency.   
     
     
         3 . The air-conditioning system of  claim 1 ,
 wherein the controller is configured to finish controlling the inverter regulated at the output frequency when the thermostat ON signal is input, and turn off the compressor or cause the compressor to perform at a maximum frequency.   
     
     
         4 . The air-conditioning system of  claim 1 ,
 wherein the controller is configured to finish controlling the inverter regulated at the output frequency when a time during which the inverter is controlled at the output frequency exceeds a predetermined operation time, and turn off the compressor or cause the compressor to perform at a maximum frequency.   
     
     
         5 . The air-conditioning system of  claim 4 , further comprising an outdoor temperature sensor that detects an outdoor temperature and transmits the outdoor temperature to the controller,
 wherein the controller is configured to determine duration of the predetermined operation time depending on a difference between the indoor temperature and the outdoor temperature.