Linear compressor

Abstract

A linear compressor is provided that may include a shell including a refrigerant inlet, an outer stator provided in the shell and including a coil, an inner stator disposed to be spaced apart from the outer stator, a permanent magnet disposed to be movable between the outer stator and the inner stator, a cylinder including a compression space, in which a refrigerant sucked in through refrigerant inlet may be compressed, a piston coupled to the permanent magnet so as to be reciprocated in the cylinder, a first surface area provided on the piston and having a first hardness value, and a second surface area provided on the cylinder and having a second hardness value, such that a difference value between the first and second hardness values is more than a preset value.

What is claimed is: 
     
         1 . A linear compressor, comprising:
 a shell comprising a refrigerant inlet;   an outer stator provided in the shell and comprising a coil;   an inner stator disposed to be spaced apart from the outer stator;   a permanent magnet disposed movable between the outer stator and the inner stator;   a cylinder comprising a compression space in which a refrigerant sucked in through the refrigerant inlet is compressed;   a piston coupled to the permanent magnet to be reciprocated in the cylinder;   a first surface area provided on the piston, the first surface area having a first hardness value; and   a second surface area provided on the cylinder, the second surface area having a second hardness value, so that a difference in value between the first and second hardness values is more than a predetermined value.   
     
     
         2 . The linear compressor according to  claim 1 , wherein the predetermined value is at least approximately 150Hv or more based on Vickers hardness. 
     
     
         3 . The linear compressor according to  claim 1 , wherein the predetermined value is determined so that an abrasion amount generated at the piston or the cylinder, while the piston is repeatedly reciprocated for a predetermined period of time, is approximately 3 μm or less. 
     
     
         4 . The linear compressor according to  claim 2 , wherein the first surface area or the second surface area is made of one of polytetra fluoroethylene (PTFE), diamond like carbon (DLC), an Ni—P alloy, or an anodizing layer. 
     
     
         5 . The linear compressor according to  claim 4 , wherein the first surface area comprises one of PTFE, DLC, Ni—P alloy, or an anodizing layer, and wherein the second surface area comprises another one of PTFE, DLC, Ni—P alloy, or an anodizing layer, which is different from the first surface area. 
     
     
         6 . The linear compressor according to  claim 5 , wherein the first surface area is made of PTFE, and the second surface area is made of the anodizing layer. 
     
     
         7 . The linear compressor according to  claim 1 , wherein the piston and the cylinder are made of a non-magnetic material. 
     
     
         8 . The linear compressor according to  claim 7 , wherein the piston and the cylinder are made of aluminum or an aluminum alloy. 
     
     
         9 . The linear compressor according to  claim 8 , wherein the aluminum or the aluminum alloy of the piston and the cylinder are the same material. 
     
     
         10 . The linear compressor according to  claim 1 , wherein the first surface area is provided on an outer circumferential surface of the piston, and the second surface area is provided on an inner circumferential surface of the cylinder, which is disposed opposite to the outer circumferential surface of the piston. 
     
     
         11 . The linear compressor according to  claim 1 , wherein the piston comprises:
 a piston body received in the cylinder; and   a flange that extends in a radial direction of the piston body and coupled to the permanent magnet, and wherein the first surface area is provided on an outer circumferential surface of the piston body.   
     
     
         12 . A linear compressor comprising a piston reciprocated in a cylinder by a force generated by an interaction between a magnetic flux generated by a current applied to a coil and a magnetic flux of a permanent magnet, the linear compressor comprising:
 a first surface area provided on an outer circumferential surface of the piston; and   a second surface area provided on an inner circumferential surface of the cylinder, wherein a predetermined difference in hardness value is provided between a hardness value of the first surface area and a hardness value of the second surface area.   
     
     
         13 . The linear compressor according to  claim 12 , wherein the predetermined difference in hardness value is at least approximately 150Hv or more based on Vickers hardness. 
     
     
         14 . The linear compressor according to  claim 12 , wherein the first surface area comprises one of polytetra fluoroethylene (PTFE), diamond like carbon (DLC), an Ni—P alloy, or an anodizing layer, and the second surface area comprises another one of PTFE, DLC, Ni—P alloy, or an anodizing layer, which is different from the first surface area. 
     
     
         15 . A linear compressor, comprising:
 a shell comprising a refrigerant inlet;   an outer stator provided in the shell and comprising a coil;   an inner stator disposed to be spaced apart from the outer stator;   a permanent magnet disposed movable between the outer stator and the inner stator;   a cylinder comprising a compression space in which a refrigerant sucked in through the refrigerant inlet is compressed;   a piston coupled to the permanent magnet to be reciprocated in the cylinder;   a polytera fluroethylene (PTFE) layer provided on an outer circumferential surface of the piston; and   an anodizing layer provided on an inner circumferential surface of the cylinder.   
     
     
         16 . A linear compressor, comprising:
 a shell comprising a refrigerant inlet;   an outer stator provided in the shell and comprising a coil;   an inner stator disposed to be spaced apart from the outer stator;   a permanent magnet disposed movable between the outer stator and the inner stator;   a cylinder comprising a compression space in which a refrigerant sucked in through the refrigerant inlet is compressed and having a first surface area having a first hardness value; and   a piston coupled to the permanent magnet to be reciprocated in the cylinder and having a second surface area having a second hardness value, wherein a difference in value between the first hardness value and the second hardness value allows slippage between the cylinder and the piston.   
     
     
         17 . The linear compressor according to  claim 16 , wherein the predetermined value is at least approximately 150Hv or more based on Vickers hardness. 
     
     
         18 . The linear compressor according to  claim 16 , wherein the predetermined value is determined so that an abrasion amount generated at the piston or the cylinder, while the piston is repeatedly reciprocated for a predetermined period of time, is approximately 3 μm or less. 
     
     
         19 . The linear compressor according to  claim 16 , wherein the first surface area or the second surface area is made of one of polytetra fluoroethylene (PTFE), diamond like carbon (DLC), an Ni—P alloy, or an anodizing layer. 
     
     
         20 . The linear compressor according to  claim 19 , wherein the first surface area comprises one of PTFE, DLC, Ni—P alloy, or an anodizing layer, and wherein the second surface area comprises another one of PTFE, DLC, Ni—P alloy, or an anodizing layer, which is different from the first surface area. 
     
     
         21 . The linear compressor according to  claim 20 , wherein the first surface area is made of PTFE, and the second surface area is made of the anodizing layer. 
     
     
         22 . The linear compressor according to  claim 16 , wherein the piston and the cylinder are made of a non-magnetic material. 
     
     
         23 . The linear compressor according to  claim 22 , wherein the piston and the cylinder are made of aluminum or an aluminum alloy. 
     
     
         24 . The linear compressor according to  claim 23 , wherein the aluminum or the aluminum alloy of the piston and the cylinder are the same material.