Linear compressor

Abstract

A linear compressor is provided. The linear compressor may include a cylinder that forms a compression space for a refrigerant, a piston that reciprocates in an axial direction inside of the cylinder, and a linear motor that supplies power to the piston. The linear motor may include an outer stator including a first stator magnetic pole, a second stator magnetic pole, and an opening defined between the first stator magnetic pole and the second stator magnetic pole; an inner stator disposed apart from the outer stator to form an air gap therebetween; and a permanent magnet movably disposed in the air gap between the outer stator and the inner stator and having three poles. The three poles may include two end magnetic poles, and a central magnetic pole disposed between the two end magnetic poles. The piston may be moveable by a stroke between a top dead center position and a bottom dead center position, and a length of the first stator magnetic pole or the second stator magnetic pole may be greater than a length of the stroke.

What is claimed is: 
     
         1 . A linear compressor, comprising:
 a cylinder that forms a compression space for a refrigerant;   a piston that reciprocates in an axial direction inside of the cylinder; and   a linear motor that supplies power to the piston, wherein the linear motor comprises:
 an outer stator comprising a first stator magnetic pole, a second stator magnetic pole, and an opening defined between the first stator magnetic pole and the second stator magnetic pole; 
 an inner stator disposed apart from the outer stator to form an air gap therebetween; and 
 a permanent magnet movably disposed in the air gap between the outer stator and the inner stator and having three poles, wherein the three poles include:
 two end magnetic poles; and 
 a central magnetic pole disposed between the two end magnetic poles, wherein the piston is moveable by a stroke between a top dead center position and a bottom dead center position, and wherein a length of the first stator magnetic pole or the second stator magnetic pole is greater than a length of the stroke. 
 
   
     
     
         2 . The linear compressor according to  claim 1 , wherein the central magnetic pole has a length greater than a length of any one of the two end magnetic poles. 
     
     
         3 . The linear compressor according to  claim 2 , wherein the length of the central magnetic pole is twice or less than the length of the any one of the two end magnetic poles. 
     
     
         4 . The linear compressor according to  claim 1 , wherein a length of the central magnetic pole is equal to or less than a sum of lengths of the two end magnetic poles. 
     
     
         5 . The linear compressor according to  claim 1 , wherein an axial direction length of the opening is equal to or greater than a radial direction height of the air gap. 
     
     
         6 . The linear compressor according to  claim 1 , wherein a length of any one of the two end magnetic poles is approximately 90% or more of a length of the first stator magnetic pole or the second stator magnetic pole. 
     
     
         7 . The linear compressor according to  claim 1 , wherein the two end magnetic poles comprise:
 a first pole coupled to the central magnetic pole at a first interface; and   a second pole coupled to the central magnetic pole at a second interface.   
     
     
         8 . The linear compressor according to  claim 7 , wherein the first interface reciprocates in an axial direction between both ends of the first stator magnetic pole, based on a center of the first stator magnetic pole, and the second interface reciprocates in an axial direction between both ends of the second stator magnetic pole, based on a center of the second stator magnetic pole. 
     
     
         9 . The linear compressor according to  claim 7 , wherein the first pole comprises an end at a position that faces the first interface, and wherein the end of the first pole is positioned outside of the outer stator when the piston is positioned at the bottom dead center position. 
     
     
         10 . The linear compressor according to  claim 9 , wherein the end of the first pole is positioned at an end of or outside of the first stator magnetic pole when the piston is positioned at the top dead center position. 
     
     
         11 . The linear compressor according to  claim 1 , wherein the two end magnetic poles comprise a first pole coupled to a first side of the central magnetic pole, and wherein at least a portion of the first pole is positioned in the air gap between the first stator magnetic pole and the inner stator. 
     
     
         12 . The linear compressor according to  claim 11 , wherein the two end magnetic poles comprise a second pole coupled to a second side of the central magnetic pole, and wherein at least a portion of the second pole is positioned in the air gap between the second stator magnetic pole and the inner stator. 
     
     
         13 . The linear compressor according to  claim 1 , wherein the opening is defined between a tip of the first stator magnetic pole and a tip of the second stator magnetic pole, at a side of an accommodation space that accommodates a coil. 
     
     
         14 . The linear compressor according to  claim 1 , wherein the piston and the cylinder are made of aluminum or aluminum alloy. 
     
     
         15 . A linear compressor, comprising:
 a cylinder that forms a compression space for a refrigerant;   a piston that reciprocates in an axial direction inside of the cylinder; and   a linear motor that supplies power to the piston, wherein the linear motor comprises:
 an outer stator comprising a first stator magnetic pole, a second stator magnetic pole, and an opening defined between the first stator magnetic pole and the second stator magnetic pole; 
 an inner stator disposed apart from the outer stator to form an air gap therebetween; and 
 a permanent magnet movably disposed in the air gap between the outer stator and the inner stator and having three poles, wherein the three poles include:
 two end magnetic poles; and 
 a central magnetic pole disposed between the two end magnetic poles, wherein the piston is moveable by a stroke between a top dead center position and a bottom dead center position, wherein a length of the first stator magnetic pole or the second stator magnetic pole is greater than a length of the stroke, and wherein the permanent magnet is made of a ferrite material. 
 
   
     
     
         16 . The linear compressor according to  claim 15 , wherein the central magnetic pole has a length greater than a length of any one of the two end magnetic poles. 
     
     
         17 . The linear compressor according to  claim 15 , wherein a length of the central magnetic pole is equal to or less than a sum of lengths of the two end magnetic poles. 
     
     
         18 . The linear compressor according to  claim 15 , wherein an axial direction length of the opening is equal to or greater than a radial direction height of the air gap. 
     
     
         19 . The linear compressor according to  claim 15 , wherein a length of any one of the two end magnetic poles is approximately 90% or more of a length of the first stator magnetic pole or the second stator magnetic pole. 
     
     
         20 . The linear compressor according to  claim 15 , wherein the two end magnetic poles comprise:
 a first pole coupled to the central magnetic pole at a first interface; and   a second pole coupled to the central magnetic pole at a second interface.   
     
     
         21 . The linear compressor according to  claim 20 , wherein the first interface reciprocates in an axial direction between both ends of the first stator magnetic pole, based on a center of the first stator magnetic pole, and the second interface reciprocates in an axial direction between both ends of the second stator magnetic pole, based on a center of the second stator magnetic pole. 
     
     
         22 . The linear compressor according to  claim 20 , wherein the first pole comprises an end at a position that faces the first interface, and wherein the end of the first pole is positioned outside of the outer stator when the piston is positioned at the bottom dead center position. 
     
     
         23 . The linear compressor according to  claim 22 , wherein the end of the first pole is positioned at an end of or outside of the first stator magnetic pole when the piston is positioned at the top dead center position. 
     
     
         24 . The linear compressor according to  claim 15 , wherein the two end magnetic poles comprise a first pole coupled to a first side of the central magnetic pole, wherein at least a portion of the first pole is positioned in the air gap between the first stator magnetic pole and the inner stator, and wherein the two end magnetic poles comprise a second pole coupled to a second side of the central magnetic pole, and wherein at least a portion of the second pole is positioned in the air gap between the second stator magnetic pole and the inner stator. 
     
     
         25 . The linear compressor according to  claim 24 , wherein the piston and the cylinder are made of aluminum or aluminum alloy.