Patent Publication Number: US-2021172658-A1

Title: Refrigeration appliance and method for operating the refrigeration appliance

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority, under 35 U.S.C. § 119, of Chinese patent application CN 201911232023.4, filed Dec. 5, 2019; the prior application is herewith incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     Embodiments of the present invention relate to a refrigeration appliance and a method for operating the refrigeration appliance. 
     A compressor of the refrigeration appliance is generally started when a startup condition is reached and stops working when a stop condition is reached. For example, when at least one storage room has a cooling request, the compressor is started to refrigerate the storage room, and when cooling requests of all storage rooms are satisfied, the compressor is turned off. For a refrigeration system including at least two refrigeration cycles, opening and closing of each refrigeration cycle is generally controlled by using a fluid control unit such as a reversing valve, a stop valve, or a rotary valve, to selectively run a corresponding refrigeration cycle to cool a corresponding storage room. 
     BRIEF SUMMARY OF THE INVENTION 
     An objective of embodiments of the present invention is to provide a method for a refrigeration appliance and a refrigeration appliance. 
     Therefore, an aspect of the embodiments of the present invention relates to a method for a refrigeration appliance, including: running a compressor to supply at least one of a plurality of branches connected in parallel at inlets thereof with a refrigerant, where each branch has a corresponding evaporator; and determining, based on an ambient temperature, whether at least one branch is open after the compressor is turned off. 
     Optionally, the branch may include a first branch for cooling a first storage room that is a freezer, and whether the first branch is open after the compressor is turned off is determined based on the ambient temperature. 
     Optionally, the branch may include a second branch for cooling a second storage room that includes a non-freezing temperature zone, and whether the second branch is open after the compressor is turned off is determined based on the ambient temperature. 
     Optionally, a first ambient temperature range in which the first branch is closed after the compressor is turned off is wider than a second ambient temperature range in which the second branch is closed after the compressor is turned off, or a first ambient temperature range in which the first branch is closed after the compressor is turned off is the same as a second ambient temperature range in which the second branch is closed after the compressor is turned off. 
     Optionally, when the ambient temperature is less than 20 degrees centigrade, if the ambient temperature is less than a lower limit of the first ambient temperature range, the first branch is open after the compressor is turned off, and if the ambient temperature is less than a lower limit of the second ambient temperature range, the second branch is open after the compressor is turned off, where the lower limit of the first ambient temperature range is less than or equal to the lower limit of the second ambient temperature range. When the ambient temperature is greater than 20 degrees centigrade, if the ambient temperature is greater than an upper limit of the first ambient temperature range, the first branch is open after the compressor is turned off, and if the ambient temperature is greater than an upper limit of the second ambient temperature range, the second branch is open after the compressor is turned off, where the upper limit of the first ambient temperature range is greater than or equal to the upper limit of the second ambient temperature range. 
     Another aspect of the embodiments of the present invention relates to a method for a refrigeration appliance, including: running a compressor; opening at least one of a first branch and a second branch, where the first branch has a first evaporator, the second branch has a second evaporator, and the first branch and the second branch are connected in parallel at inlets thereof; determining, based on an ambient temperature, whether the first branch is open after the compressor is turned off; and/or determining, based on the ambient temperature, whether the second branch is open after the compressor is turned off. 
     Optionally, when the ambient temperature is within the first ambient temperature range, the first branch is closed after the compressor is turned off. When the ambient temperature is outside of the first ambient temperature range, the first branch is open after the compressor is turned off. 
     It should be understood that the first ambient temperature range and the second ambient temperature range may be continuous respectively or include at least two separate subranges. 
     Optionally, the first ambient temperature range includes a lower limit that is less than 20 degrees centigrade and/or an upper limit that is greater than 20 degrees centigrade. 
     Optionally, when the ambient temperature is within the second ambient temperature range, the second branch is closed after the compressor is turned off, and when the ambient temperature is outside of the second ambient temperature range, the second branch is open after the compressor is turned off. 
     Optionally, the second ambient temperature range includes a lower limit that is less than 20 degrees centigrade and/or an upper limit that is greater than 20 degrees centigrade. 
     Still another aspect of the embodiments of the present invention relates to a refrigeration appliance. The refrigeration appliance includes a compressor, a plurality of branches connected in parallel at inlets thereof, where each branch has a corresponding evaporator, and a fluid control unit, configured to selectively open at least one of the branches, so that when the compressor is running, a corresponding evaporator in the opened branch is supplied with a refrigerant output from the compressor. The refrigeration appliance further has a control unit, where the control unit is configured to determine, based on an ambient temperature, whether at least one of the branches is open after the compressor is turned off. 
     Optionally, the branch includes a first branch, and whether the first branch is open after the compressor is turned off is determined based on the ambient temperature. 
     Optionally, the branch includes a second branch, and whether the second branch is open after the compressor is turned off is determined based on the ambient temperature. 
     Optionally, the control unit is configured to determine, based on the ambient temperature, whether all the branches are open after the compressor is turned off. 
     Optionally, the control unit is configured to determine, based on the ambient temperature, whether all the branches are open after the compressor is turned off. 
     Still another aspect of the embodiments of the present invention relates to a refrigeration appliance, including a compressor, a first branch, which has a first evaporator, and a second branch, which has a second evaporator. Wherein an inlet of the first branch and an inlet of the second branch are connected in parallel. When the compressor is running and the first branch is open, the first evaporator is supplied with a refrigerant output from the compressor, and when the compressor is running and the second branch is open, the second evaporator is supplied with a refrigerant output from the compressor. A control unit is provided, where the control unit is coupled to the compressor. The control unit is configured to determine, based on an ambient temperature, whether the first branch is open after the compressor is turned off, and/or the control unit is configured to determine, based on the ambient temperature, whether the second branch is open after the compressor is turned off. 
     Optionally, when the ambient temperature is within the first ambient temperature range, the first branch is closed after the compressor is turned off. When the ambient temperature is outside of the first ambient temperature range, the first branch is open after the compressor is turned off. 
     Optionally, the first ambient temperature range includes a lower limit that is less than 20 degrees centigrade and/or an upper limit that is greater than 20 degrees centigrade. 
     Optionally, when the ambient temperature is within the second ambient temperature range, the second branch is closed after the compressor is turned off, and when the ambient temperature is outside of the second ambient temperature range, the second branch is open after the compressor is turned off. 
     Optionally, the second ambient temperature range includes a lower limit that is less than 20 degrees centigrade and/or an upper limit that is greater than 20 degrees centigrade. 
     Optionally, the first evaporator is configured to cool a first storage room that is a freezer, the second evaporator is configured to cool a second storage room that includes a non-freezing temperature zone, and the first ambient temperature range in which the first branch is closed after the compressor is turned off is wider than or equal to the second ambient temperature range in which the second branch is closed after the compressor is turned off. 
     Optionally, the second ambient temperature range is within the first ambient temperature range. 
     Optionally, when the ambient temperature is less than 20 degrees centigrade, if the ambient temperature is less than a lower limit of the first ambient temperature range, the first branch is open after the compressor is turned off, and if the ambient temperature is less than a lower limit of the second ambient temperature range, the second branch is open after the compressor is turned off, where the lower limit of the first ambient temperature range is less than or equal to the lower limit of the second ambient temperature range. When the ambient temperature is greater than 20 degrees centigrade, if the ambient temperature is greater than an upper limit of the first ambient temperature range, the first branch is open after the compressor is turned off, and if the ambient temperature is greater than an upper limit of the second ambient temperature range, the second branch is open after the compressor is turned off, where the upper limit of the first ambient temperature range is greater than or equal to the upper limit of the second ambient temperature range. 
     Optionally, the fluid control unit includes a first valve located between the inlet of the first branch and the first evaporator and a second valve located between the inlet of the second branch and the second evaporator. 
     Optionally, the fluid control unit includes a rotary valve, where the rotary valve includes a first outlet coupled to the first branch and a second outlet coupled to the second branch. 
     According to the embodiments of the present invention, whether at least one branch is closed may be determined based on the ambient temperature, thereby helping to obtain a better balance between reliability and energy efficiency of a refrigeration system. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a refrigeration appliance and a method for a refrigeration appliance, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a schematic diagram of a refrigeration appliance according to an embodiment of the present invention; 
         FIG. 2  is a schematic diagram of a refrigeration system of the refrigeration appliance according to another embodiment of the present invention; 
         FIG. 3  is a schematic diagram of the refrigeration system of the refrigeration appliance according to still another embodiment of the present invention; 
         FIG. 4  is a block system diagram of the refrigeration appliance according to an embodiment of the present invention; 
         FIG. 5  is a flow chart describing a method for operating a refrigeration appliance according to an embodiment of the present invention; 
         FIG. 6-1  is a schematic diagram of temperature division of an ambient temperature according to an embodiment of the present invention; 
         FIG. 6-2  is a schematic diagram of temperature division of an ambient temperature according to another embodiment of the present invention; 
         FIG. 6-3  is a schematic diagram of temperature division of an ambient temperature according to still another embodiment of the present invention; 
         FIG. 6-4  is a schematic diagram of temperature division of an ambient temperature according to still another embodiment of the present invention; 
         FIG. 7-1  is a schematic diagram of statuses of a compressor, a first branch, and a second branch when an ambient temperature is within a first ambient temperature range and a second ambient temperature range according to an embodiment of the present invention; and 
         FIG. 7-2  is a schematic diagram of statuses of the compressor, the first branch, and the second branch when an ambient temperature is outside of a first ambient temperature range and a second ambient temperature range according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An aspect of embodiments of the present invention relates to a method for operating a refrigeration appliance, which includes: running a compressor to supply at least one of a plurality of branches connected in parallel at inlets thereof with a refrigerant, where each branch has a corresponding evaporator; and determining, based on an ambient temperature, whether at least one branch is open after the compressor is turned off. 
     Another aspect of embodiments of the present invention relates to a refrigeration appliance. The refrigeration appliance includes a compressor, a plurality of branches connected in parallel at inlets thereof, where each branch has a corresponding evaporator and a fluid control unit, configured to selectively open at least one of the branches, so that when the compressor is running, a corresponding evaporator in the opened branch is supplied with a refrigerant output from the compressor. A control unit is provided where the control unit is configured to determine, based on an ambient temperature, whether at least one of the branches is open after the compressor is turned off. 
     The branches may include at least two branches including corresponding evaporators. 
     In some embodiments, the branch may include a first branch for cooling a freezer, and the method for a refrigeration appliance may include determining, based on an ambient temperature, whether the first branch is open after the compressor is turned off. 
     In some embodiments, the branch may include a second branch for cooling a second storage room that includes a non-freezing temperature zone, and whether the second branch is open after the compressor is turned off is determined based on the ambient temperature. 
     Embodiments of the present invention are described below in detail with reference to the accompanying drawings. 
     Referring now to the figures of the drawings in detail and first, particularly to  FIG. 1  thereof, there is shown a schematic diagram of a refrigeration appliance  100  according to an embodiment of the present invention. As shown in  FIG. 1 , the refrigeration appliance  100  includes a first storage room  1  and a second storage room  2 . 
     The first storage room  1  and the second storage room  2  are thermally isolated. The first storage room  1  and the second storage room  2  may be disposed adjacent to each other or separated by another storage room. 
     The refrigeration appliance  100  includes a refrigeration system  3  for cooling the first storage room  1  and the second storage room  2 . In an exemplary embodiment, the refrigeration system  3  includes a compressor  4 , a condenser  5 , an expansion device (not shown in  FIG. 1 ), a fluid control unit  7 , a first evaporator  81 , and a second evaporator  82  that are connected through a pipeline transporting a refrigerant. The first evaporator  81  is configured to cool the first storage room  1 , and the second evaporator  82  is configured to cool the second storage room  2 . 
     A flow direction of the refrigerant is exemplarily shown by arrows on the pipeline connecting the components in  FIG. 1 . The refrigerant may flow to a first branch  31  and a second branch  32  connected in parallel at inlets thereof through the condenser  5  after output from the compressor  4 . The first branch  31  includes the first evaporator  81 , and the second branch  32  includes the second evaporator  82 . In this way, a parallel double-cycle refrigeration system is formed. 
     In an exemplary embodiment, a set temperature of the second storage room  2  is higher than that of the first storage room  1 . Evaporating pressure of the second storage room  2  is higher than evaporating pressure of the first storage room  1 . 
     For example, the first storage room  1  is a freezer, and the second storage room  2  is a storage room including a non-freezing temperature zone. For example, a set temperature range of the second storage room  2  may be any range selected from −4 degrees to 12 degrees, such as 2 degrees centigrade to 8 degrees centigrade, 2 degrees centigrade to 12 degrees centigrade, −2 degrees centigrade to 2 degrees centigrade, −4 degrees centigrade to 4 degrees centigrade, or 0 degrees centigrade to 2 degrees centigrade. 
     The fluid control unit  7  is configured to selectively supply the refrigerant output from the condenser  5  to the first branch  31  and/or the second branch  32 . The fluid control unit  7  is located at the downstream of the condenser  5 . 
     A dryer  63  may be disposed between the fluid control unit  7  and the condenser  5 . In this embodiment, the first branch  31  and the second branch  32  are connected in parallel at the dryer  63 . 
     Such setting of the fluid control unit  7  enables the first branch  31  and the second branch  32  be open or closed independently. For example, the first branch  31  may be open or closed regardless of whether the second branch  32  is open, and vice versa. 
     The fluid control unit  7  may include a first stop valve  71  located at the first branch  31  for controlling opening and closing of the first branch  31 . When the first stop valve  71  opens the first branch  31 , the refrigerant output from the compressor  4  may be supplied to the first evaporator  81  of the first branch  31 , to cool the first storage room  1  corresponding to the first evaporator  81 . The first stop valve  71  is located between the dryer  63  and the first evaporator  81 . 
     The fluid control unit  7  may include a second stop valve  72  located at the second branch  32  for controlling the second branch  32 . When the second stop valve  72  opens the second branch  32 , the refrigerant output from the compressor  4  may be supplied to the second evaporator  82  located at the second branch  32 , to cool the second storage room  2  corresponding to the second evaporator  82 . The second stop valve  72  is located between the dryer  63  and the second evaporator  82 . 
     The refrigeration appliance  100  may include a first fan  121  for the first storage room  1  and a second fan  122  for the second storage room  2 . When the first storage room  1  is cooled, the first fan  121  works. When the second storage room  2  is cooled, the second fan  122  works. 
     The refrigeration appliance  100  may include a third fan  51  disposed adjacent to the condenser  5  for improving heat dissipation efficiency of the condenser  5 . 
       FIG. 2  is a refrigeration system  3   a  for the refrigeration appliance  100  according to another embodiment of the present invention. A main difference between the refrigeration system  3   a  and the refrigeration system  3  shown in  FIG. 1  lies in the fluid control unit. 
     As shown in  FIG. 2 , the refrigeration system  3   a  includes a compressor  4   a , a condenser  5   a , a dryer  63   a , a fluid control unit  7   a , and a first evaporator  81   a  and a second evaporator  82   a  located at the downstream of the fluid control unit  7   a . A first expansion device  61   a  may be disposed between the first evaporator  81   a  and the fluid control unit  7   a , and a second expansion device  62   a  is disposed between the second evaporator  82   a  and the fluid control unit  7   a.    
     The refrigeration system  3   a  may include a first fan  121   a  for the first storage room  1  and a second fan  122   a  for the second storage room  2 . The refrigeration system  3   a  may include a third fan  51   a  disposed adjacent to the condenser  5   a  for improving heat dissipation efficiency of the condenser  5   a.    
     The fluid control unit  7   a  includes a rotary valve  71   a . The rotary valve  71   a  includes a first outlet in communication with the first branch  31   a  and a second outlet in communication with the second branch  32   a . The first branch  31   a  and the second branch  32   a  are connected in parallel through the rotary valve  71   a.    
     The rotary valve  71   a  may include a stepmotor, to determine the opening and closing of the first outlet and the second outlet according to a position of the stepmotor. Four cases that only the first outlet is open, only the second outlet is open, both the first outlet and the second outlet are open, and both the first outlet and the second outlet are closed may be implemented by controlling the stepmotor of the rotary valve  71   a.    
     When only the first outlet is open, a refrigerant output from the compressor  4   a  may flow to the first branch  31   a  after passing through the condenser  5   a  and be supplied to the first evaporator  81   a . The refrigerant is evaporated in the first evaporator  81   a , and the first storage room  1  is cooled. 
     When only the second outlet is open, the refrigerant output from the compressor  4   a  may flow to the second branch  32   a  and be supplied to the second evaporator  82   a . The refrigerant is evaporated in the second evaporator  82   a , and the second storage room  2  is cooled. 
     When both the first outlet and the second outlet are open, the refrigerant output from the compressor  4   a  may concurrently flow to the first branch  31   a  to be supplied to the first evaporator  81   a  and flow to the second branch  32   a  to be supplied to the second evaporator  82   a . The refrigerant is evaporated in the first evaporator  81   a  and the second evaporator  82   a  respectively, and the first storage room  1  and the second storage room  2  may be cooled at the same time. 
       FIG. 3  is a refrigeration system  3   b  for the refrigeration appliance  100  according to another embodiment of the present invention. As shown in  FIG. 3 , the refrigeration system  3   b  includes a compressor  4   b , a condenser  5   b , a dryer  63   b , a fluid control unit  7   b , and a first evaporator  81   b  and a second evaporator  82   b  located at the downstream of the fluid control unit  7   b . The first evaporator  81   b  is configured to cool the first storage room  1 , and the second evaporator  82   b  is configured to cool the second storage room  2 . 
     A first expansion device  61   b  may be disposed between an entrance end of the first evaporator  81   b  and an exit end of the fluid control unit  7   b , and a second expansion device  62   b  is disposed between an entrance end of the second evaporator  82   b  and the exit end of the fluid control unit  7   b.    
     The fluid control unit  7   b  may have a same structure as the fluid control unit  7   a , and details are not described herein again. 
     The refrigeration system  3   b  may include a first fan  121   b  for the first storage room  1  and a second fan  122   b  for the second storage room  2 . The refrigeration system  3   b  may further include a third fan  51   b  disposed adjacent to the condenser  5   b  for improving heat dissipation efficiency of the condenser  5   b.    
     Different from the embodiment in  FIG. 2 , in the embodiment shown in  FIG. 3 , a refrigerant output from the second evaporator  82   b  returns to the compressor  4   b  through the first evaporator  81   b , which is beneficial to improving refrigeration efficiency of the refrigeration system. This advantage becomes especially obvious when the first evaporator  81   b  cools a freezer and the second evaporator  82   b  cools a refrigeration temperature zone. 
     When the refrigerant is only supplied to the first branch  31   b  of the first branch  31   b  and the second branch  32   b  by controlling the fluid control unit  7   b , the refrigerant is evaporated in the first evaporator  81   b  to cool the first storage room  1 . 
     When the refrigerant is only supplied to the second branch  32   b  of the first branch  31   b  and the second branch  32   b , the second storage room  2  is cooled. Sometimes, the refrigerant that is not completely evaporated and output from the second evaporator  32   b  may be evaporated in the first evaporator  81   b  to improve the efficiency of the refrigeration system  3   b.    
     When the rotary valve  71   b  opens the first branch  31   b  and the second branch  32   b  at the same time to supply the refrigerant to both of the first branch  31   b  and the second branch  32   b  at the same time, the first storage room  1  and the second storage room  2  are cooled at the same time. 
     Referring to  FIG. 4  in combination with  FIG. 1  to  FIG. 3 , the refrigeration appliance  100  may include a first temperature detection unit  91  for detecting a temperature of the first storage room  1  and a second temperature detection unit  92  for detecting a temperature of the second storage room  2 . The first temperature detection unit  91  and the second temperature detection unit  92  may respectively include at least one temperature sensor. 
     In an exemplary embodiment, the first temperature detection unit  91  and the second temperature detection unit  92  respectively include at least two temperature sensors. The temperatures of the first storage room  1  and the second storage room  2  may be respectively obtained through calculation by using the at least two temperature sensors. 
     The refrigeration appliance  100  may include an input unit  10  for receiving user input. The input unit  10  may receive a set temperature Tset 1  of a user for the first storage room  1  and a set temperature Tset 1  of the user for the second storage room  2 . Generally, a set temperature Tset 1  of a storage room is an expected temperature of the user for the storage room. 
     In an exemplary embodiment, at least a part of the input unit  10  and/or a control unit  11  may be disposed on a main body  101  of the refrigeration appliance  100  and/or a door (not shown in the figure) for closing the storage room. 
     In another embodiment, at least a part of the input unit  10  and/or the control unit  11  of the refrigeration appliance  100  is disposed in a remote device independent of and outside of the main body  101 /the door of the refrigeration appliance. For example, the user may set the set temperatures of the first storage room  1  and the second storage room  2  through a remote terminal. In another example, temperature information obtained by the temperature detection unit disposed on the main body  101  is transmitted to the control unit  11  located at a remote server, and the refrigeration system  3 ,  3   a ,  3   b  is controlled based on instructions of the remote control unit  11 . 
     An environment parameter such as an ambient temperature and/or an ambient humidity may also be used as an input parameter of the control unit  11  for controlling the refrigeration system  3 . The refrigeration appliance  100  may include an ambient temperature sensor  93  for detecting a temperature of an environment in which the refrigeration appliance  100  is located. The refrigeration appliance  100  may include an ambient humidity sensor (not shown in the figure) for detecting a humidity of an environment in which the refrigeration appliance  100  is located. 
     The refrigeration appliance  100  includes a control unit  11 . The control unit  11  is coupled to the first temperature detection unit  91 , the second temperature detection unit  92 , the ambient temperature sensor  93 , the input unit  10 , and the refrigeration system  3 ,  3   a ,  3   b . According to feedback of the first temperature detection unit  91 , the second temperature detection unit  92 , and the ambient temperature sensor  93 , the control unit  11  controls the compressor  4 ,  4   a ,  4   b , the fluid control unit  7 ,  7   a ,  7   b , the first fan  121 ,  121   a ,  121   b , the second fan  122 ,  122   a ,  122   b , and the third fan  51 ,  51   a ,  51   b  of the refrigeration system  3 ,  3   a ,  3   b  to work. 
     The control unit  11  may be configured to respectively determine, according to information of the first temperature detection unit  91  and the second temperature detection unit  92 , whether the first storage room  1  and the second storage room  2  have a cooling request. An existing method may be used to determine whether a storage room has a cooling request. For example, in an embodiment, when a temperature of the first storage room  1  is greater than a startup temperature of the first storage room  1 , it is determined that the first storage room  1  has a cooling request. When the temperature of the first storage room  1  reaches a stop temperature of the first storage room  1 , the cooling request of the first storage room  1  is satisfied, and the refrigeration system  3 ,  3   a ,  3   b  may stop cooling the first storage room  1 . similar method may also be used for the second storage room  2 . A startup temperature and a stop temperature of a storage room may be determined according to a set temperature thereof in combination with other parameters such as an ambient temperature. 
     According to an embodiment of the present invention, a method S 50  for the refrigeration appliance  100  includes: S 51 , when at least one of the first storage room  1  and the second storage room  2  has a cooling request, starting the compressor  4 ,  4   a ,  4   b  to supply at least one of a first branch  31 ,  31   a ,  31   b  and a second branch  32 ,  32   a ,  32   b  connected in parallel at inlets thereof with a refrigerant; and S 52 , determining, based on an ambient temperature, whether the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off, and/or determining, based on the ambient temperature, whether the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     The control unit  11  may be configured to determine, according to ambient temperature information measured by the ambient temperature sensor  93 , whether the first branch  31 ,  31   a ,  31   b  and/or the second branch  32 ,  32   a ,  32   b  are open after the compressor is turned off. 
     Opening or closing of the first branch  31 ,  31   a ,  31   b  and/or the second branch  32 ,  32   a ,  32   b  may be implemented by the fluid control unit  7 ,  7   a ,  7   b.    
     In some embodiments, statuses of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  after the compressor  4 ,  4   a ,  4   b  is turned off are related to the ambient temperature. Therefore, the step of whether to open at least one of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  after the compressor  4 ,  4   a ,  4   b  is turned off is determined based on the ambient temperature may include: determining, based on the ambient temperature, whether to open the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  after the compressor  4 ,  4   a ,  4   b  is turned off. 
     For example, in some embodiments, when the ambient temperature is within a first ambient temperature range, the first branch  31 ,  31   a ,  31   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off. When the ambient temperature is outside of the first ambient temperature range, the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. In another example, when the ambient temperature is within a second ambient temperature range, the second branch  32 ,  32   a ,  32   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off. When the ambient temperature is outside of the second ambient temperature range, the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     When the ambient temperature is within the first ambient temperature range and the second ambient temperature range, as shown in  FIG. 7-1 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed after the compressor  4 ,  4   a ,  4   b  is turned off. 
     When the ambient temperature is outside of the first ambient temperature range and the second ambient temperature range, as shown in  FIG. 7-2 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     The first ambient temperature range for determining whether the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off may be equal to the second ambient temperature range for determining whether the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     In some embodiments, as shown in  FIG. 6-1 , if the ambient temperature is greater than a first threshold T 11 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed after the compressor  4 ,  4   a ,  4   b  is turned off. 
     If the ambient temperature is less than the first threshold T 11 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     In some embodiments, the first threshold T 11  may be less than 20 degrees centigrade. That is, the first ambient temperature range and the second ambient temperature range have a lower limit less than 20 degrees centigrade. 
     The first threshold T 11  may be any value selected from 8 degrees centigrade to 15 degrees centigrade. Preferably, the first threshold T 11  may be located between 10 degrees centigrade and 12 degrees centigrade. 
     For a frequency variable compressor  4 ,  4   a ,  4   b , even the compressor is started at a low speed at a relatively low ambient temperature, since at least one cooling branch is open when the compressor is started, pressure difference in the refrigeration system  3 ,  3   a ,  3   b  is small, which is beneficial to safe start of the compressor. 
     In some embodiments, as shown in  FIG. 6-2 , if the ambient temperature is less than a second threshold T 21 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed after the compressor  4 ,  4   a ,  4   b  is turned off. If the ambient temperature is greater than the second threshold T 21 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     In some embodiments, the second threshold T 21  may be greater than 20 degrees centigrade. That is, the first ambient temperature range and the second ambient temperature range may have upper limits greater than 20 degrees centigrade. 
     The second threshold T 21  may be any value selected from 28 degrees centigrade to 37 degrees centigrade. Preferably, the second threshold T 21  may be located between 30 degrees centigrade and 36 degrees centigrade. 
     Therefore, when the ambient temperature is high, after the compressor  4 ,  4   a ,  4   b  is turned off, at least one branch is open, thereby helping to balance the pressure difference between a high pressure side and a low pressure side in the refrigeration system  3 ,  3   a ,  3   b . When the compressor  4 ,  4   a ,  4   b  is started again, a start resistance for the compressor can be reduced, which facilitates safe starting of the compressor. 
     In still some embodiments, as shown in  FIG. 6-3 , if the ambient temperature is between the first threshold T 11  and the second threshold T 21 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed after the compressor  4 ,  4   a ,  4   b  is turned off. If the ambient temperature is greater than the second threshold T 21  or the ambient temperature is less than the first threshold T 11 , the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     The first threshold T 11  may be less than 20 degrees centigrade. The second threshold T 21  may be greater than 20 degrees centigrade. Therefore, the first ambient temperature range and the second ambient temperature range respectively have a lower limit less than 20 degrees centigrade and an upper limit greater than 20 degrees centigrade. 
     The first threshold T 11  may be any value selected from 8 degrees centigrade to 15 degrees centigrade. Preferably, the first threshold T 11  may be located between 10 degrees centigrade and 12 degrees centigrade. 
     The second threshold T 21  may be any value selected from 28 degrees centigrade to 37 degrees centigrade. Preferably, the second threshold T 21  may be located between 30 degrees centigrade and 36 degrees centigrade. 
     Based on this, the ambient temperature is divided into three ranges: a low temperature range, an intermediate temperature range, and a high temperature range. When the measured ambient temperature is within the intermediate temperature range, after the compressor is turned off, the first branch and the second branch are closed. Because the intermediate temperature is a temperature section within which a majority of using conditions of a user fall, after the compressor is turned off, the pressure difference between the high pressure side and the low pressure side in the refrigeration system may be maintained by closing the first branch and the second branch, so that when the compressor is started again, no additional energy needs to be consumed to establish pressure difference, thereby helping to save energy. When the measured ambient temperature is within the low temperature range and the high temperature range, the reliability of the starting of the compressor may be improved by opening at least one branch. 
     In the embodiments described above, the first ambient temperature range for determining whether the first branch is open after the compressor  4 ,  4   a ,  4   b  is turned off is equal to the second ambient temperature range for determining whether the second branch is open after the compressor  4 ,  4   a ,  4   b  is turned off. In another embodiment, the first ambient temperature range for determining whether the first branch is open after the compressor  4 ,  4   a ,  4   b  is turned off may be different from the second ambient temperature range for determining whether the second branch is open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     In some embodiments, the first ambient temperature range in which the first branch  31 ,  31   a ,  31   b  is open after the compressor is turned off may be defined based on any one of  FIG. 6-1  to  FIG. 6-3 , and the second ambient temperature range in which the second branch  32 ,  32   a ,  32   b  is open after the compressor is turned off may be defined based on another of  FIG. 6-1  to  FIG. 6-3 . For example, if the ambient temperature is less than the first threshold T 11 , one of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  is open after the compressor is turned off, and if the ambient temperature is greater than the first threshold T 11 , the one of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  is closed after the compressor is turned off. If the ambient temperature is greater than the second threshold T 21 , another of the first branch 
       31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  is open after the compressor is turned off, and if the ambient temperature is less than the second threshold T 21 , the another of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  is closed after the compressor is turned off. 
     In another example, if the ambient temperature is less than the first threshold T 11  or the ambient temperature is greater than the second threshold T 21 , the first branch  31 ,  31   a ,  31   b  is open after the compressor is turned off. If the ambient temperature is between the first threshold T 11  and the second threshold T 21 , the first branch  31 ,  31   a ,  31   b  is closed after the compressor is turned off. If the ambient temperature is greater than the second threshold T 21 , the second branch  32 ,  32   a ,  32   b  is open after the compressor is turned off, and if the ambient temperature is less than the second threshold T 21 , the second branch  32 ,  32   a ,  32   b  is closed after the compressor is turned off. 
     In some other embodiments, opening and closing of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  may be both based on any temperature range in  FIG. 6-1  to  FIG. 6-3 , but the two branches may have different thresholds. 
     Therefore, for example, when the ambient temperature is less than 20 degrees centigrade, if the ambient temperature is less than the first threshold, the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off, and if the ambient temperature is less than the second threshold, the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off, where the first threshold is less than the second threshold. 
     In another example, when the ambient temperature is greater than 20 degrees centigrade, if the ambient temperature is greater than a third threshold, the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off, and if the ambient temperature is greater than a fourth threshold, the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off, where the third threshold is greater than the fourth threshold. 
     As shown in  FIG. 6-4 , when the ambient temperature is between a first threshold T 41  and a third threshold T 42 , the first branch  31 ,  31   a ,  31   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off. When the ambient temperature is outside of the first threshold T 41  to the third threshold T 42 , the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. If the ambient temperature is between a second threshold T 51  and a fourth threshold T 52 , the second branch  32 ,  32   a ,  32   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off. If the ambient temperature is outside of the second threshold T 51  to the fourth threshold T 52 , the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. The first threshold T 41  is less than the second threshold T 51 , or the third threshold T 42  is greater than the fourth threshold T 52 . 
     Evaporation pressure of running of the second branch  32 ,  32   a ,  32   b  for cooling the second storage room  2  is higher than that of the first branch  31 ,  31   a ,  31   b  for cooling the first storage room  1 , so that a starting load of the compressor  4 ,  4   a ,  4   b  is greater. If a greater temperature range for opening the second branch  32 ,  32   a ,  32   b  after the compressor is turned off is provided, it is beneficial to further improving the energy efficiency and reliability of the refrigeration system. 
     When the ambient temperature is between the first threshold T 41  and the second threshold T 51 , the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off, and the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     When the ambient temperature is between the fourth threshold T 52  and the third threshold T 42 , the first branch  31 ,  31   a ,  31   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off, and the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. 
     Although in  FIG. 6-4 , the first threshold T 41  used as the lower limit of the first ambient temperature range is less than the second threshold T 51  used as the lower limit of the second ambient temperature range, and the third threshold T 42  that is the upper limit of the first ambient temperature range is greater than the fourth threshold T 52  that is the upper limit of the second ambient temperature range. In another embodiment, it is possible that the first threshold T 41  is equal to the second threshold T 51 , or the third threshold T 42  is equal to the fourth threshold T 52 . 
     In the foregoing embodiments, statuses of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  after the compressor  4 ,  4   a ,  4   b  is turned off are both related to the ambient temperature. In another embodiment, there may be a case that a status of only one of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  after the compressor  4 ,  4   a ,  4   b  is turned off is related to the ambient temperature. 
     For example, in an embodiment, determining whether to open the first branch  31 ,  31   a ,  31   b  after the compressor  4 ,  4   a ,  4   b  is turned off based on the ambient temperature. When the ambient temperature is within a preset temperature range, the first branch  31 ,  31   a ,  31   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off. When the ambient temperature is outside of the temperature range, the first branch  31 ,  31   a ,  31   b  is open after the compressor  4 ,  4   a ,  4   b  is turned off. A temperature range for determining whether the first branch  31 ,  31   a ,  31   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off may use any one in  FIG. 6-1  to  FIG. 6-3 . 
     In another implementation, determining whether to open the second branch  32 ,  32   a ,  32   b  after the compressor  4 ,  4   a ,  4   b  is turned off based on the ambient temperature. When the ambient temperature is within the preset temperature range, the second branch  32 ,  32   a ,  32   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off. When the ambient temperature is outside of the preset temperature range, the second branch  32 ,  32   a ,  32   b  is open after the compressor  4 ,  4   a ,  4   b . A temperature range for determining whether the second branch  32 ,  32   a ,  32   b  is closed after the compressor  4 ,  4   a ,  4   b  is turned off may use any one in  FIG. 6-1  to  FIG. 6-3 . 
     According to different statuses of the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b , that the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed after the compressor  4 ,  4   a ,  4   b  is turned off may include: switching from an open state before the compressor is turned off to a closed state or maintaining an existing closed state before the compressor is turned off to maintain pressure difference between a high pressure side and a low pressure side in the refrigeration system. 
     According to different statuses of the first branch  31 ,  31   a ,  31   b  and second branch  32 ,  32   a ,  32   b , that the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open after the compressor  4 ,  4   a ,  4   b  is turned off may include: switching from a closed state before the compressor is turned off to an open state or maintaining an existing open state before the compressor is turned off to reduce pressure difference between the high pressure side and the low pressure side in the refrigeration system. 
     That the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed after the compressor  4 ,  4   a ,  4   b  is turned off to maintain pressure difference between the high pressure side and the low pressure side in the refrigeration system may include that: the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are continuously open in a period in which the compressor  4 ,  4   a ,  4   b  is turned off or are in a closed state in most time of this period to implement the objective of maintaining pressure difference between the high pressure side and the low pressure side in the refrigeration system. 
     That the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are continuously closed in the period in which the compressor  4 ,  4   a ,  4   b  is turned off may be that since the compressor is turned off, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are closed immediately to maintain pressure difference between the high pressure side and the low pressure side in the refrigeration system. As a variant, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are in a closed state in most time of the period in which the compressor  4 ,  4   a ,  4   b  is turned off to maintain pressure difference between the high pressure side and the low pressure side in the refrigeration system, and in the period in which the compressor  4 ,  4   a ,  4   b  is turned off, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are transiently (for example, not longer than 2 minutes) in an open state so as not to obviously reduce pressure difference between the high pressure side and the low pressure side in the refrigeration system. 
     That the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open after the compressor  4 ,  4   a ,  4   b  is turned off may include that: in the period in which the compressor  4 ,  4   a ,  4   b  is turned off, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are continuously in an open state or in an open state in most time of the period to reduce pressure difference between the high pressure side and the low pressure side in the refrigeration system. 
     That the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are continuously open in the period in which the compressor  4 ,  4   a ,  4   b  is turned off may be that since the compressor is turned off, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are open immediately to reduce pressure difference between the high pressure side and the low pressure side in the refrigeration system. As a variant, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are in an open state in most time of the period in which the compressor  4 ,  4   a ,  4   b  is turned off to reduce pressure difference between the high pressure side and the low pressure side in the refrigeration system. For example, in the period in which the compressor  4 ,  4   a ,  4   b  is turned off, the first branch  31 ,  31   a ,  31   b  and the second branch  32 ,  32   a ,  32   b  are transiently (for example, not longer than 10 minutes) in a closed state so as not to obviously affect a balance process of pressure difference between the high pressure side and the low pressure side in the refrigeration system. 
     In the foregoing embodiments, the principle of the present invention is described by using a refrigeration system including two refrigeration cycles as an example. It should be understood that, the principle of the present invention may alternatively be applicable to a refrigeration system including more refrigeration cycles/branches. For example, the principle of the present invention may alternatively be applicable to a three-cycle refrigeration system including three branches connected in parallel at inlets thereof. 
     In addition, in the foregoing embodiments, when the compressor is running, both the first branch and the second branch may be open to enable both the first evaporator and the second evaporator to be supplied with a refrigerant. However, the principle of the present invention may similarly be applicable to a refrigeration system in which a refrigerant is supplied to the first branch and the second branch in a switching manner. 
     Although the refrigeration appliance and the method for a refrigeration appliance are described above based on a specific shape and direction with reference to the accompanying drawings, a person skilled in the art may be aware that, variations may be made without departing from the principle and spirit of the present disclosure. In other words, although exemplary implementations are shown and described, a person skilled in the art may be aware that, variations may be made to these implementations without departing from the principle and spirit of the present disclosure, and the scope of the present disclosure is as defined by the appended claims and their equivalents.