Method for controlling linear compressor and refrigerator

Abstract

A method for controlling a linear compressor and a method for controlling a refrigerator are provided. The method for controlling a linear compressor may include measuring an ambient temperature, and when the measured ambient temperature is equal to or lower than a predetermined safety temperature, applying a safety current to a motor assembly for driving a piston. On the other hand, when the measured ambient temperature is higher than the predetermined safety temperature, a current lower than the safety current may be applied to the motor assembly.

What is claimed is: 
     
         1 . A method for controlling a linear compressor including a piston and a bearing flow path configured to supply bearing refrigerant to the piston, the method comprising:
 measuring an ambient temperature;   when the measured ambient temperature is equal to or lower than a predetermined safety temperature, applying a safety current to a motor assembly for driving the piston; and   when the measured ambient temperature is higher than the predetermined safety temperature, applying a current lower than the safety current to the motor assembly.   
     
     
         2 . The method of  claim 1 , further comprising:
 turning on the linear compressor; and   when the measured ambient temperature is higher than the predetermined safety temperature, applying a drive current greater than a minimum applied current and smaller than a maximum applied current to the motor assembly, wherein the maximum applied current is smaller than the safety current.   
     
     
         3 . The method of  claim 2 , further comprising:
 after applying the drive current to the motor assembly, again measuring the ambient temperature;   when the measured ambient temperature is equal to or lower than the predetermined safety temperature, applying the safety current to the motor assembly; and   when the measured ambient temperature is higher than the predetermined safety temperature, continuously applying the drive current to the motor assembly.   
     
     
         4 . The method of  claim 3 , further comprising:
 after applying the safety current to the motor assembly, again measuring the ambient temperature;   when the measured ambient temperature is equal to or lower than the predetermined safety temperature, continuously applying the safety current to the motor assembly; and   when the measured ambient temperature is higher than the predetermined safety temperature, applying the drive current to the motor assembly.   
     
     
         5 . The method of  claim 2 , wherein, when the maximum applied current is applied to the motor assembly, the piston is reciprocated between a maximum top dead center and a maximum bottom dead center, wherein, when the safety current is applied to the motor assembly, the piston is reciprocated between a safety top dead center and a safety bottom dead center, and wherein a safety stroke distance which is a distance between the safety top dead center and the safety bottom dead center is longer than a maximum stroke distance which is a distance between the maximum top dead center and the maximum bottom dead center. 
     
     
         6 . The method of  claim 5 , wherein the piston is reciprocated in an axial direction, wherein the safety top dead center is located in front of the maximum top dead center in the axial direction, and wherein the safety bottom dead center is located at a rear of the maximum bottom dead center in the axial direction. 
     
     
         7 . The method of  claim 1 , further comprising:
 turning off the linear compressor;   when the measured ambient temperature is equal to or lower than the predetermined the safety temperature, applying a safety current to the motor assembly;   after applying the safety current, measuring the ambient temperature;   when the measured ambient temperature is equal to or lower than the predetermined safety temperature, continuously applying the safety current to the motor assembly; and   when the measured ambient temperature is higher than the predetermined safety temperature, stopping applying the safety current to the motor assembly.   
     
     
         8 . The method of  claim 1 , wherein the bearing flow path includes a cylinder bearing flow path formed in a cylinder in which the piston is received and a frame bearing flow path formed in a frame in which the cylinder is received, wherein the piston is reciprocated by the motor assembly to compress refrigerant, and wherein at least a portion of compressed refrigerant flows into the cylinder bearing flow path and the frame bearing flow path and is supplied to the piston. 
     
     
         9 . The method of  claim 8 , wherein the cylinder bearing flow path includes:
 a gas inlet recessed inward from an outer circumferential surface of the cylinder in a radial direction; and   a cylinder nozzle extended from the gas inlet to an inner circumferential surface of the cylinder.   
     
     
         10 . The method of  claim 1 , wherein the motor assembly includes:
 an outer stator having a coil to which current is applied;   an inner stator disposed inside of the outer stator; and   a permanent magnet disposed movably inside of the outer stator and the inner stator, the permanent magnet being connected to the piston, wherein, when the safety current is applied to the coil, the bearing refrigerant is expanded by heat generated in the coil.   
     
     
         11 . The method of  claim 1 , wherein the ambient temperature corresponds to an outer temperature of a shell in which the piston is received and to which a suction pipe and a discharge pipe are coupled through which the refrigerant flows into the shell and is discharged from the shell, respectively. 
     
     
         12 . The method of  claim 1 , wherein the safety temperature is 10 degrees. 
     
     
         13 . A method for controlling a refrigerator equipped with a linear compressor, the method comprising:
 measuring an internal temperature and an external temperature of a storage chamber;   when the measured internal temperature is equal to or higher than a predetermined temperature in the refrigerator, applying a drive current which is higher than a minimum applied current and lower than a maximum applied current to the linear compressor; and   when the measured external temperature is equal to or lower than a predetermined safety temperature, applying a safety current to the linear compressor, wherein the maximum applied current corresponds to a current value smaller than the predetermined safety current.   
     
     
         14 . The method of  claim 13 , further comprising:
 when the measured external temperature is equal to or lower than the predetermined safety temperature and the measured internal temperature is equal to or higher than the temperature in the refrigerator, applying the safety current to the linear compressor.   
     
     
         15 . The method of  claim 13 , further comprising:
 when the measured external temperature is higher than the predetermined safety temperature and the measured internal temperature is equal to or higher than the predetermined temperature in the refrigerator, applying the drive current to the linear compressor, wherein the higher the external temperature, the greater the current value of the drive current.   
     
     
         16 . A method for controlling a linear compressor, the linear compressor including a shell having suction and discharge pipes through which a fluid flows into and out of the shell, a frame received by the shell, a cylinder received by the frame, a piston received by the cylinder, a motor assembly that drives the piston to reciprocate axially within the cylinder to compress the fluid, and a bearing flow path that extends through the frame and the cylinder and configured to supply bearing fluid to the piston, the method comprising:
 measuring an ambient temperature corresponding to an outer temperature of the shell;   when the measured ambient temperature is equal to or lower than a predetermined safety temperature, applying a safety current to the motor assembly; and   when the measured ambient temperature is higher than the predetermined safety temperature, applying a current lower than the safety current to the motor assembly.   
     
     
         17 . The method of  claim 16 , further comprising:
 turning on the linear compressor; and   when the measured ambient temperature is higher than the predetermined safety temperature, applying a drive current greater than a minimum applied current and smaller than a maximum applied current to the motor assembly, wherein the maximum applied current is smaller than the safety current.   
     
     
         18 . The method of  claim 17  further comprising:
 after applying the drive current to the motor assembly, again measuring the ambient temperature; 
 when the measured ambient temperature is equal to or lower than the predetermined safety temperature, applying the safety current to the motor assembly; and 
 when the measured ambient temperature is higher than the predetermined safety temperature, continuously applying the drive current to the motor assembly. 
 
     
     
         19 . The method of  claim 18 , further comprising:
 after applying the safety current to the motor assembly, again measuring the ambient temperature;   when the measured ambient temperature is equal to or lower than the predetermined safety temperature, continuously applying the safety current to the motor assembly; and   when the measured ambient temperature is higher than the predetermined safety temperature, applying the drive current to the motor assembly.   
     
     
         20 . The method of  claim 16 , wherein the safety temperature is 10 degrees.