Air-conditioning device, railway vehicle air-conditioning device, and method for controlling air-conditioning device

Abstract

An air-conditioning device includes (i) a compressor, (ii) an outdoor heat exchanger, (iii) an indoor heat exchanger and an electronic expansion valve, (iv) a bypass passage connecting a middle compression chamber and a low pressure space, the middle compression chamber accommodating a refrigerant undergoing compression by the compressor, the low pressure space accommodating the refrigerant having a pressure lower than a pressure of the refrigerant in the middle compression chamber, (v) a bypass valve to open or close the bypass passage, and (vi) a controller to set a degree of opening of the electronic expansion valve based on a degree of superheat of a refrigerant. Based on a change from a closed state of the bypass valve to an open state, the controller corrects the degree of opening of the electronic expansion valve to a value that is less than a value set by the degree-of-superheat control.

1 . An air-conditioning device including a refrigerant circuit in which a compressor, an outdoor heat exchanger, an indoor heat exchanger and an electronic expansion valve are connected to one another via refrigerant piping, the air-conditioning device comprising:
 a bypass passage communicatively connecting a middle compression chamber and a low pressure space, the middle compression chamber being a chamber to accommodate a refrigerant undergoing compression by the compressor, the low pressure space being a space to accommodate the refrigerant having a pressure lower than a pressure of the refrigerant in the middle compression chamber;   a bypass valve to open or close the bypass passage; and   a controller to execute degree-of-superheat control in which a degree of opening of the electronic expansion valve is set based on a degree of superheat of the refrigerant,   wherein based on a change from a closed state of the bypass valve to an open state of the bypass valve, the controller starts restriction processing in which the degree of opening of the electronic expansion valve is corrected to a value that is less than the value set by the degree-of-superheat control.   
     
     
         2 . The air-conditioning device according to  claim 1 , wherein
 the controller comprises a pressure detector for detecting a pressure of a refrigerant that flows into the compressor, and   a condition for a start of the restriction processing is that the pressure as a result of the detection by the pressure detector is equal to or higher than a first given pressure.   
     
     
         3 . An air-conditioning device including a refrigerant circuit in which a compressor, an outdoor heat exchanger, an indoor heat exchanger and an electronic expansion valve are connected to one another via refrigerant piping, the air-conditioning device comprising:
 a bypass passage communicatively connecting a middle compression chamber and a low pressure space, the middle compression chamber being a chamber to accommodate a refrigerant undergoing compression by the compressor, the low pressure space being a space to accommodate the refrigerant having a pressure lower than a pressure of the refrigerant in the middle compression chamber;   a bypass valve to open or close the bypass passage; and   a controller to execute degree-of-superheat control in which a degree of opening of the electronic expansion valve is set based on a degree of superheat of the refrigerant,   wherein   upon detecting a change request to change a state of the bypass valve from an open state to a closed state, the controller starts facilitation processing in which the degree of opening of the electronic expansion valve is corrected to a value that is greater than the value set by the degree-of-superheat control, and the controller subsequently changes the state of the bypass valve from the open state to the closed state.   
     
     
         4 . The air-conditioning device according to  claim 1 , wherein
 upon start-up of the compressor, the degree of opening of the electronic expansion valve is set to a start-up degree of opening, and the bypass valve is set to the open state.   
     
     
         5 . An air-conditioning apparatus for a railroad vehicle comprising the air-conditioning device according to  claim 1 , wherein
 the compressor is arranged such that the compressor is inclined relative to a horizontal plane.   
     
     
         6 . A method of controlling an air-conditioning device including (i) a refrigerant circuit in which a compressor, an outdoor heat exchanger, an indoor heat exchanger and an electronic expansion valve are connected to one another via refrigerant piping, (ii) a bypass passage communicatively connecting a middle compression chamber and a low pressure space, the middle compression chamber being a chamber to accommodate a refrigerant undergoing compression by the compressor, the low pressure space being a space to accommodate the refrigerant having a pressure lower than a pressure of the refrigerant in the middle compression chamber, and (iii) a bypass valve to open or close the bypass passage, the method comprising:
 a degree-of-superheat control step of setting a degree of opening of the electronic expansion valve based on a degree of superheat of the refrigerant; and 
 a restriction step of correcting, based on a change from a closed state of the bypass valve to an open state of the bypass valve, the degree of opening of the electronic expansion valve to a value less than the value set in the degree-of-superheat control step. 
 
     
     
         7 . The method according to  claim 6 , further comprising:
 facilitation step of correcting, when a change request to change a state of the bypass valve from an open state to a closed state is detected, the degree of opening of the electronic expansion valve to a value that is greater than the value set in the degree-of-superheat control step.