Mode Switcher, Heat Recovery Multi-Split Air Conditioning System and Control Method

Abstract

A mode switcher includes at least one mode conversion branch. The mode conversion branch includes: a liquid pipe section, a high-pressure gas pipe section and a low-pressure gas pipe section. The mode switcher further includes a high-pressure electronic expansion valve and a low-pressure electronic expansion valve, the high-pressure electronic expansion valve and the low-pressure electronic expansion valve are respectively arranged in series in the high-pressure gas pipe section and the low-pressure gas pipe section, so as to gradually be opened and closed during air conditioning mode switching to reduce a differential pressure between before and after a mode conversion operation. A heat recovery multi-split air conditioning system and control method are further provided.

1 . A mode switcher, comprising at least one mode conversion branch, wherein the at least one mode conversion branch comprises: a liquid pipe section, a high-pressure gas pipe section and a low-pressure gas pipe section, both ends of the liquid pipe section are respectively configured to connect a main liquid pipe and a branch liquid pipe, one end of the high-pressure gas pipe section and one end of the low-pressure gas pipe section are respectively configured to connect a main high-pressure gas pipe and a main low-pressure gas pipe, another end of the high-pressure gas pipe section and another end of the low-pressure gas pipe section are configured to both connect with a branch gas pipe, the mode switcher further comprises a high-pressure electronic expansion valve and a low-pressure electronic expansion valve, the high-pressure electronic expansion valve and the low-pressure electronic expansion valve are respectively arranged in series in the high-pressure gas pipe section and the low-pressure gas pipe section, so as to gradually be opened and closed during air conditioning mode switching to reduce a differential pressure between before and after a mode conversion operation. 
     
     
         2 . The mode switcher according to  claim 1 , wherein the at least one mode conversion branch further comprises a high-pressure solenoid valve and a low-pressure solenoid valve, and the high-pressure solenoid valve and the low-pressure solenoid valve are respectively connected in parallel with the high-pressure electronic expansion valve and the low-pressure electronic expansion valve through bypass pipelines. 
     
     
         3 . The mode switcher according to  claim 1 , wherein the liquid pipe section is further connected with a supercooling pipe in series so as to perform heat exchange on a refrigerant of the liquid pipe section and a refrigerant led from the main liquid pipe to the main low-pressure gas pipe. 
     
     
         4 . The heat recovery multi-split air conditioning system according to  claim 1 , wherein all mode conversion branches are connected in parallel, in series, or in series-parallel form through the main liquid pipe, the main high-pressure gas pipe and the main low-pressure gas pipe. 
     
     
         5 . A heat recovery multi-split air conditioning system, comprising an outdoor unit, an indoor unit and the mode switcher of  claim 1 , wherein the outdoor unit is connected with various mode conversion branches in the mode switcher through a main liquid pipe, a main high-pressure gas pipe and a main low-pressure gas pipe, and the mode conversion branches are connected with a corresponding indoor unit through a branch liquid pipe and a branch gas pipe. 
     
     
         6 . The heat recovery multi-split air conditioning system according to  claim 5 , wherein a muffler is arranged on at least one of the main high-pressure gas pipe and the main low-pressure gas pipe connecting the mode switcher. 
     
     
         7 . The heat recovery multi-split air conditioning system according to  claim 5 , wherein the liquid pipe section is further connected with a supercooling pipe in series, the heat recovery multi-split air conditioning system further comprises a first bypass pipeline led from the main liquid pipe to the main low-pressure gas pipe, the first bypass pipeline is connected with the supercooling pipe and performs heat exchange, and a filter and a supercooling throttling unit are arranged in series in the first bypass pipeline. 
     
     
         8 . The heat recovery multi-split air conditioning system according to  claim 5 , further comprising a second bypass pipeline arranged between the main high-pressure gas pipe and the main low-pressure gas pipe, and wherein a gas bypass solenoid valve and a throttling unit are arranged in series in the second bypass pipeline. 
     
     
         9 . A control method of the mode switcher of  claim 1 , comprising at least one of the following steps:
 upon receiving a switching instruction of switching from a cooling mode to a heating mode, controlling the low-pressure electronic expansion valve to gradually decrease an opening degree at a preset step size, until the low-pressure electronic expansion valve is closed; and then controlling the high-pressure electronic expansion valve to be opened, adjusting the high-pressure electronic expansion valve to a preset initial opening degree, and after maintaining the preset initial opening degree for a preset time length, causing the high-pressure electronic expansion valve to gradually increase the opening degree at the preset step size, until the high-pressure electronic expansion valve is opened to a maximum opening degree;   upon receiving a switching instruction of switching from the heating mode to the cooling mode, causing the high-pressure electronic expansion valve to gradually decrease the opening degree at a preset step size, until the high-pressure electronic expansion valve is closed; and then causing the low-pressure electronic expansion valve to be opened, adjusting the low-pressure electronic expansion valve to a preset initial opening degree, and after maintaining the preset initial opening degree for a preset time length, causing the low-pressure electronic expansion valve to gradually increase the opening degree at the preset step size, until the low-pressure electronic expansion valve is opened to a maximum opening degree.   
     
     
         10 . The control method according to  claim 9 , wherein the at least one mode conversion branch further comprises a high-pressure solenoid valve and a low-pressure solenoid valve, and the high-pressure solenoid valve and the low-pressure solenoid valve are respectively connected in parallel with the high-pressure electronic expansion valve and the low-pressure electronic expansion valve through bypass pipelines; and the control method further comprises:
 upon receiving the switching instruction of switching from the cooling mode to the heating mode, causing the low-pressure solenoid valve to be closed, and opening the high-pressure solenoid valve when causing the high-pressure electronic expansion valve to be opened to the maximum opening degree; or   upon receiving the switching instruction of switching from the heating mode to the cooling mode, causing the high-pressure solenoid valve to be closed, and opening the low-pressure solenoid valve when causing the low-pressure electronic expansion valve to be opened to the maximum opening degree.