Patent Publication Number: US-10323630-B2

Title: Linear compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims the benefits of priority to Korean Patent Application No. 10-2016-0054878, filed in Korea on May 3, 2016, which is herein incorporated by reference in its entirety. 
     BACKGROUND 
     1. Field 
     A linear compressor is disclosed herein. 
     2. Background 
     Cooling systems are systems in which a refrigerant circulates to generate cool air. In such a cooling system, processes of compressing, condensing, expanding, and evaporating the refrigerant are repeatedly performed. The cooling system includes a compressor, a condenser, an expansion device, and an evaporator. Also, the cooling system may be installed or provided in a home appliance including a refrigerator or an air conditioner. 
     In general, compressors are machines that receive power from a power generation device, such as an electric motor or a turbine, to compress air, a refrigerant, or various gaseous working fluids, thereby increasing a pressure and a temperature. The compressors are being widely used in home appliances or industrial fields. 
     Such a compressor is largely classified into a reciprocating compressor, a scroll compressor, and a rotary compressor. In recent years, development of a linear compressor belonging to one kind of reciprocating compressor has been actively carried out. The linear compressor may be directly connected to a drive motor, in which a piston is linearly reciprocated, to improve compression efficiency without mechanical loss due to movement conversion and have a simple structure. 
     In general, the linear compressor suctions a gaseous refrigerant while a piston is moved to linearly reciprocate within a cylinder by a linear motor and then compresses the suctioned refrigerant at a high-temperature and a high-pressure to discharge the compressed refrigerant. 
     A linear compressor is disclosed in Korean Patent Publication No. 10-2016-0005516 (hereinafter referred to as “prior art document”), published Jan. 1, 2016, which is hereby incorporated by reference. The linear compressor includes a shell, a linear motor provided in the shell to generate drive power, a piston driven by the linear motor, a cylinder in which the piston is accommodated, and a discharge cover that defines a discharge space for a refrigerant compressed while the piston reciprocates. The linear compressor may further include a discharge part provided in the shell and a loop pipe connecting the discharge part to the discharge cover. 
     According to the prior art document, as coupling between the loop pipe and the discharge cover or between the loop pipe and the discharge part is not firm, movement of the loop pipe may occur due to a pressure of the discharged refrigerant. In addition, the coupling between the loop pipe and the discharge cover or between the loop pipe and the discharge part may be released to cause leakage of the refrigerant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein: 
         FIG. 1  is a perspective view illustrating an outer appearance of a linear compressor according to an embodiment; 
         FIG. 2  is an exploded perspective view illustrating a shell and a shell cover of the linear compressor according to an embodiment; 
         FIG. 3  is an exploded perspective view illustrating internal parts or components of the linear compressor according to an embodiment; 
         FIG. 4  is a cross-sectional view, taken along line I-I′ of  FIG. 1 ; 
         FIG. 5  is a perspective view illustrating a state in which a loop pipe is coupled to a cover pipe; 
         FIG. 6  is a cross-sectional view, taken along line II-III′ of  FIG. 5 ; 
         FIG. 7  is a view illustrating a state just before a first coupling part or portion of the loop pipe is coupled to the cover pipe; and 
         FIG. 8  is a cross-sectional view, taken along line III-III′ of  FIG. 5  in a state in which a second coupling part or portion of the loop pipe is coupled to a discharge pipe. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Where possible, like reference numerals have been used to indicate like elements, and repetitive disclosure has been omitted. 
       FIG. 1  is a perspective view illustrating an outer appearance of a linear compressor according to an embodiment.  FIG. 2  is an exploded perspective view illustrating a shell and a shell cover of the linear compressor according to an embodiment. 
     Referring to  FIGS. 1 and 2 , a linear compressor  10  according to an embodiment may include a shell  101  and shell covers  102  and  103  coupled to the shell  101 . Each of the first and second shell covers  102  and  103  may be understood as one component of the shell  101 . 
     A leg  50  may be coupled to a lower portion of the shell  101 . The leg  50  may be coupled to a base of a product in which the linear compressor  10  is installed or provided. For example, the product may include a refrigerator, and the base may include a machine room base of the refrigerator. For another example, the product may include an outdoor unit of an air conditioner, and the base may include a base of the outdoor unit. 
     The shell  101  may have an approximately cylindrical shape and be disposed to lie in a horizontal direction or an axial direction. In  FIG. 1 , the shell  101  may extend in the horizontal direction and have a relatively low height in a radial direction. That is, as the linear compressor  10  has a low height, when the linear compressor  10  is installed or provided in the machine room base of the refrigerator, a machine room may be reduced in height. 
     A terminal  108  may be installed or provided on an outer surface of the shell  101 . The terminal  108  may transmit external power to a motor (see reference numeral  140  of  FIG. 3 ) of the linear compressor  10 . The terminal  108  may be connected to a lead line of a coil (see reference numeral  141   c  of  FIG. 3 ). 
     A bracket  109  may be installed or provided outside of the terminal  108 . The bracket  109  may include a plurality of brackets that surrounds the terminal  108 . The bracket  109  may protect the terminal  108  against an external impact. 
     Both sides of the shell  101  may be open. The shell covers  102  and  103  may be coupled to both open sides of the shell  101 . The shell covers  102  and  103  may include a first shell cover  102  coupled to one open side of the shell  101  and a second shell cover  103  coupled to the other open side of the shell  101 . An inner space of the shell  101  may be sealed by the shell covers  102  and  103 . 
     In  FIG. 1 , the first shell cover  102  may be disposed at a first or right portion of the linear compressor  10 , and the second shell cover  103  may be disposed at a second or left portion of the linear compressor  10 . That is, the first and second shell covers  102  and  103  may be disposed to face each other. 
     The linear compressor  10  further includes a plurality of pipes  104 ,  105 , and  106  provided in the shell  101  or the shell covers  102  and  103  to suction, discharge, or inject the refrigerant. The plurality of pipes  104 ,  105 , and  106  may include a suction pipe  104  through which the refrigerant may be suctioned into the linear compressor  10 , a discharge pipe  105  through which the compressed refrigerant may be discharged from the linear compressor  10 , and a process pipe through which the refrigerant may be supplemented to the linear compressor  10 . 
     For example, the suction pipe  104  may be coupled to the first shell cover  102 . The refrigerant may be suctioned into the linear compressor  10  through the suction pipe  104  in the axial direction. 
     The discharge pipe  105  may be connected to the shell  101 . The refrigerant suctioned through the suction pipe  104  may be compressed in a compression space, which will be described hereinafter, while flowing in the axial direction. Also, the compressed refrigerant may be discharged through the discharge pipe  105  to the outside of the compressor  10 . The discharge pipe  105  may be disposed at a position which is adjacent to the second shell cover  103  rather than the first shell cover  102 . 
     The process pipe  106  may be coupled to the outer circumferential surface of the shell  101 . A worker may inject the refrigerant into the linear compressor  10  through the process pipe  106 . 
     The process pipe  106  may be coupled to the shell  101  at a height different from a height of the discharge pipe  105  to avoid interference with the discharge pipe  105 . The height may be understood as a distance from the leg  50  in the vertical direction (or the radial direction). As the discharge pipe  105  and the process pipe  106  are coupled to the outer circumferential surface of the shell  101  at the heights different from each other, a worker&#39;s work convenience may be improved. 
     A first stopper  102   b  may be disposed or provided on the inner surface of the first shell cover  102 . The first stopper  102   b  may prevent the compressor body  100 , particularly, the motor  140  from being damaged by vibration or an impact, which occurs when the linear compressor  10  is carried. 
     The first stopper  102   b  may be disposed adjacent to a back cover  170 , which will be described hereinafter. When the linear compressor  10  is shaken, the back cover  170  may come into contact with the first stopper  102   b  to prevent the motor  140  from directly colliding with the shell  101 . 
       FIG. 3  is an exploded perspective view illustrating internal parts or components of the linear compressor according to an embodiment.  FIG. 4  is a cross-sectional view, taken along line I-I′ of  FIG. 1 . 
     Referring to  FIGS. 3 and 4 , the linear compressor  10  according to an embodiment may include the shell  101 , a compressor body  100  accommodated in the shell  101 , and a plurality of support devices or supports  200  and  300  that supports the compressor body  100 . One of the plurality of support devices  200  and  300  may be fixed to the shell  101 , and the other one may be fixed to a pair of covers  102  and  103 . As a result, the compressor body  100  may be supported to be spaced apart from the inner circumferential surface of the shell  101 . 
     The compressor body  100  may include a cylinder  120  provided in the shell  101 , a piston  130  that linearly reciprocates within the cylinder  120 , and a motor  140  that applies a drive force to the piston  130 . When the motor  140  is driven, the piston  130  may reciprocate in the axial direction. 
     The compressor body  100  may further include a suction muffler  150  coupled to the piston  130  to reduce noise generated from the refrigerant suctioned through the suction pipe  104 . The refrigerant suctioned through the suction pipe  104  may flow into the piston  130  via the suction muffler  150 . For example, while the refrigerant passes through the suction muffler  150 , a flow noise of the refrigerant may be reduced. 
     The suction muffler  150  may include a plurality of mufflers  151 ,  152 , and  153 . The plurality of mufflers  151 ,  152 , and  153  may include a first muffler  151 , a second muffler  152 , and a third muffler  153 , which may be coupled to each other. 
     The first muffler  151  may be disposed or provided within the piston  130 , and the second muffler  152  may be coupled to a rear portion of the first muffler  151 . Also, the third muffler  153  may accommodate the second muffler  152  therein and extend to a rear side of the first muffler  151 . In view of a flow direction of the refrigerant, the refrigerant suctioned through the suction pipe  104  may successively pass through the third muffler  153 , the second muffler  152 , and the first muffler  151 . In this process, the flow noise of the refrigerant may be reduced. 
     The suction muffler  150  may further include a muffler filter  155 . The muffler filter  155  may be disposed on or at an interface on or at which the first muffler  151  and the second muffler  152  are coupled to each other. For example, the muffler filter  155  may have a circular shape, and an outer circumferential portion of the muffler filter  155  may be supported between the first and second mufflers  151  and  152 . 
     The “axial direction” may be understood as a direction in which the piston  130  reciprocates, that is, a horizontal direction in  FIG. 4 . Also, “in the axial direction”, a direction from the suction pipe  104  toward a compression space P, that is, a direction in which the refrigerant flows may be defined as a “frontward direction”, and a direction opposite to the frontward direction may be defined as a “rearward direction”. When the piston  130  moves forward, the compression space P may be compressed. On the other hand, the “radial direction” may be understood as a direction which is perpendicular to the direction in which the piston  130  reciprocates, that is, a vertical direction in  FIG. 4 . The “axis of the compressor body” may represent a central line or central longitudinal axis in the axial direction of the piston  130 . 
     The piston  130  may include a piston body  131  having an approximately cylindrical shape and a piston flange part or flange  132  that extends from the piston body  131  in the radial direction. The piston body  131  may reciprocate inside of the cylinder  120 , and the piston flange part  132  may reciprocate outside of the cylinder  120 . 
     The cylinder  120  may be configured to accommodate at least a portion of the first muffler  151  and at least a portion of the piston body  131 . The cylinder  120  may have the compression space P in which the refrigerant may be compressed by the piston  130 . Also, a suction hole  133 , through which the refrigerant may be introduced into the compression space P, may be defined in a front portion of the piston body  131 , and a suction valve  135  that selectively opens the suction hole  133  may be disposed or provided on a front side of the suction hole  133 . A coupling hole, to which a predetermined coupling member  135   a  may be coupled, may be defined in an approximately central portion of the suction valve  135 . 
     A discharge cover  160  that defines a plurality of discharge spaces for the refrigerant discharged from the compression space P and a discharge valve assembly  161  and  163  coupled to the discharge cover assembly  160  to selectively discharge the refrigerant compressed in the compression space P may be provided at a front side of the compression space P. The discharge cover assembly  160  may include a discharge cover  165  coupled to a front surface of the cylinder  120  to accommodate the discharge valve assembly  161  and  163  therein and a plurality of discharge mufflers coupled to a front surface of the discharge cover  165 . The plurality of discharge mufflers may include a first discharge muffler  168   a  coupled to the front surface of the discharge cover  165  and a second discharge muffler  168   b  coupled to a front surface of the first discharge muffler  168   a ; however, the number of discharge mufflers are not limited thereto. 
     The plurality of discharge spaces may include a first discharge space  160   a  defined inside of the discharge cover  165 , a second discharge space  160   b  defined between the discharge cover  165  and the first discharge muffler  168   a , and a third discharge space  160   c  defined between the first discharge muffler  168   a  and the second discharge muffler  168   b . The discharge valve assembly  161  and  163  may be accommodated in the first discharge space  160   a.    
     One or a plurality of discharge holes  165   a  may be defined in the discharge cover  165 , and the refrigerant discharged into the first discharge space  160   a  may be discharged into the second discharge space  160   b  through the discharge hole  165   a  and thus is reduced in discharge noise. 
     The discharge valve assembly  161  and  163  may include a discharge valve  161 , which may be opened when a pressure of the compression space P is above a discharge pressure to introduce the refrigerant into the discharge space of the discharge cover assembly  160  and a spring assembly  163  fixed to the inside of the discharge cover  165  to provide elastic force in the axial direction to the discharge valve  161 . The spring assembly  163  may include a valve spring  163   a  that applies elastic force to the discharge valve  161  and a spring support part or support  163   b  that supports the valve spring  163   a  to the discharge cover  165 . 
     For example, the valve spring  163   a  may include a plate spring. Also, the spring support part  163   b  may be integrally injection-molded to the valve spring  163   a  through an insertion-molding process. 
     The discharge valve  161  may be coupled to the valve spring  163   a , and a rear portion or a rear surface of the discharge valve  161  may be disposed to be supported on the front surface of the cylinder  120 . When the discharge valve  161  is closely attached to the front surface of the cylinder  120 , the compression space P may be maintained in a sealed state. When the discharge valve  161  is spaced apart from the front surface of the cylinder  120 , the compression space P may be opened to discharge the refrigerant compressed in the compression space P to the first discharge space  160   a.    
     The compression space P may be a space defined between the suction valve  135  and the discharge valve  161 . Also, the suction valve  135  may be disposed on or at one side of the compression space P, and the discharge valve  161  may be disposed on or at the other side of the compression space P, that is, an opposite side of the suction valve  135 . 
     While the piston  130  linearly reciprocates within the cylinder  120 , when a pressure of the compression space P is less than a pressure inside of the suction muffler  150 , the suction valve  135  may be opened, and the refrigerant introduced into the suction muffler  150  suctioned into the compression space P. Also, when the refrigerant increases in flow rate, and thus, the pressure of the compression space P is greater than the pressure inside of the suction muffler  150 , the suction valve  135  may be closed to become a state in which the refrigerant is compressible. 
     When the pressure of the compression space P is greater than the pressure of the first discharge space  106   a , the valve spring  163   a  may be elastically deformed forward to allow the discharge valve  161  to be spaced apart from the front surface of the cylinder  120 . Also, when the discharge valve  161  is opened, the refrigerant may be discharged from the compression space P to the first discharge space  160   a . When the pressure of the compression space P is less than the pressure of the first discharge space  160   a  by the discharge of the refrigerant, the valve spring  163   a  may provide a restoring force to the discharge valve  161  to allow the discharge valve  161  to be closed. 
     The compressor body  100  may further include a connection pipe  162   c  that connects the second discharge space  160   b  to the third discharge space  160   c , a cover pipe  162   a  connected to the second discharge muffler  168   b , and a loop pipe  500  that connects the cover pipe  162   a  to the discharge pipe  105 . The connection pipe  162   c  may have one or a first end that passes through the first discharge muffler  168   a  and inserted into the second discharge space  160   b  and the other or a second end connected to the second discharge muffler  158   b  to communicate with the third discharge space  160   c . Thus, the refrigerant discharged to the second discharge space  160   b  may be further reduced in noise while moving to the third discharge space  160   c  along the connection pipe  162   c . Each of the pipes  162   a ,  500 , and  162   c  may be made of a metal material. 
     The loop pipe  500  may have one or a first side or end coupled to the cover pipe  162   a  and the other or a second side or end coupled to the discharge pipe  105 . The loop pipe  500  may be made of a flexible material. Also, the loop pipe  500  may roundly extend from the cover pipe  162   a  along the inner circumferential surface of the shell  101  and be coupled to the discharge pipe  105 . For example, the loop pipe  500  may be provided in a wound shape. While the refrigerant flows along the loop pipe  500 , noise may be further reduced. 
     When the loop pipe  500  is disposed in the wound shape, a phenomenon in which force applied in a direction in which the loop pipe  500  is separated from the cover pipe  162   a  is transmitted to the loop pipe  500  may be prevented or minimized. 
     A coupling structure between the loop pipe  500  and the cover pipe  162   a  and a coupling structure between the loop pipe  500  and the discharge pipe  105  will be described hereinafter with reference to the accompanying drawings. 
     The compressor body  100  may further include a frame  110 . The frame  110  may be a part that fixes the cylinder  120 . For example, the cylinder  120  may be press-fitted into the frame  110 . 
     The frame  110  may be disposed or provided to surround the cylinder  120 . That is, the cylinder  120  may be inserted into an accommodation groove defined in the frame  110 . Also, the discharge cover assembly  160  may be coupled to a front surface of the frame  110  by using a coupling member. 
     The compressor body  100  may further include the motor  140 . The motor  140  may include an outer stator  141  fixed to the frame  110  to surround the cylinder  120 , an inner stator  148  disposed or provided to be spaced inward from the outer stator  141 , and a permanent magnet  146  disposed or provided in a space between the outer stator  141  and the inner stator  148 . 
     The permanent magnet  146  may be linearly reciprocated by mutual electromagnetic force between the outer stator  141  and the inner stator  148 . Also, the permanent magnet  146  may be provided as a single magnet having one polarity or by coupling a plurality of magnets having three polarities to each other. 
     The permanent magnet  146  may be disposed or provided on the magnet frame  138 . The magnet frame  138  may have an approximately cylindrical shape and be disposed or provided to be inserted into the space between the outer stator  141  and the inner stator  148 . 
     Referring to the cross-sectional view of  FIG. 4 , the magnet frame  138  may be bent forward after extending from the outer circumferential surface of the piston flange part or flange  132  in the radial direction. The permanent magnet  146  may be fixed to a front end of the magnet frame  138 . Thus, when the permanent magnet  146  reciprocates, the piston  130  may reciprocate together with the permanent magnet  146  in the axial direction. 
     The outer stator  141  may include coil winding bodies  141   b ,  141   c , and  141   d , and a stator core  141   a . The coil winding bodies  141   b ,  141   c , and  141   d  may include a bobbin  141   b  and a coil  141   c  wound in a circumferential direction of the bobbin  141   b . The coil winding bodies  141   b ,  141   c , and  141   d  may further include a terminal part or portion  141   d  that guides a power line connected to the coil  141   c  so that the power line is led out or exposed to the outside of the outer stator  141 . 
     The stator core  141   a  may include a plurality of core blocks in which a plurality of laminations are laminated in a circumferential direction. The plurality of core blocks may be disposed or provided to surround at least a portion of the coil winding bodies  141   b  and  141   c.    
     A stator cover  149  may be disposed on one or a first side of the outer stator  141 . That is, the outer stator  141  may have one or a first side supported by the frame  110  and the other or a second side supported by the stator cover  149 . 
     The linear compressor  10  may further include a cover coupling member  149   a  that couples the stator cover  149  to the frame  110 . The cover coupling member  149   a  may pass through the stator cover  149  to extend forward to the frame  110  and then be coupled to the frame  110 . 
     The inner stator  148  may be fixed to an outer circumference of the frame  110 . Also, in the inner stator  148 , the plurality of laminations may be laminated outside of the frame  110  in the circumferential direction. 
     The compressor body  100  may further include a support  137  that supports the piston  130 . The support  137  may be coupled to a rear portion of the piston  130 , and the muffler  150  may be disposed or provided to pass through the inside of the support  137 . The piston flange part  132 , the magnet frame  138 , and the support  137  may be coupled to each other using a coupling member. 
     A balance weight  179  may be coupled to the support  137 . A weight of the balance weight  179  may be determined based on a drive frequency range of the compressor body  100 . 
     The compressor body  100  may further include a back cover  170  coupled to the stator cover  149  to extend backward. The back cover  170  may include three support legs, however, embodiments are not limited thereto, and the three support legs may be coupled to a rear surface of the stator cover  149 . A spacer  181  may be disposed or provided between the three support legs and the rear surface of the stator cover  149 . A distance from the stator cover  149  to a rear end of the back cover  170  may be determined by adjusting a thickness of the spacer  181 . The back cover  170  may be spring-supported by the support  137 . 
     The compressor body  100  may further include an inflow guide part or guide  156  coupled to the back cover  170  to guide an inflow of the refrigerant into the muffler  150 . At least a portion of the inflow guide part  156  may be inserted into the suction muffler  150 . 
     The compressor body  100  may further include a plurality of resonant springs  176   a  and  176   b  which may be adjusted in natural frequency to allow the piston  130  to perform a resonant motion. The plurality of resonant springs  176   a  and  176   b  may include a first resonant spring  176   a  supported between the support  137  and the stator cover  149  and a second resonant spring  176   b  supported between the support  137  and the back cover  170 . The piston  130  that reciprocates within the linear compressor  10  may be stably moved by the action of the plurality of resonant springs  176   a  and  176   b  to reduce vibration or noise due to the movement of the piston  130 . 
     The compressor body  100  may further include a plurality of sealing members or seals  127  and  128  that increases a coupling force between the frame  110  and the peripheral parts or portions around the frame  110 . The plurality of sealing members  127  and  128  may include a first sealing member or seal  127  disposed or provided at a portion at which the frame  110  and the discharge cover  165  are coupled to each other. The plurality of sealing members  127  and  128  may further include a second sealing member or seal  128  disposed or provided at a portion at which the frame  110  and the cylinder  120  are coupled to each other. Each of the first and second sealing members  127  and  128  may have a ring shape. 
     The plurality of support devices  200  and  300  may include a first support device or support  200  coupled to one or a first side of the compressor body  100  and a second support device or support  300  coupled to the other or a second side of the compressor body  100 . The first support device  200  may be fixed to the first shell cover  102 , and the second support device  300  may be fixed to the shell  101 . 
       FIG. 5  is a perspective view illustrating a state in which the loop pipe is coupled to the cover pipe.  FIG. 6  is a cross-sectional view, taken along line II-II′ of  FIG. 5 .  FIG. 7  is a view illustrating a state just before a first coupling part or portion of the loop pipe is coupled to the cover pipe.  FIG. 8  is a cross-sectional view, taken along line III-III′ of  FIG. 5  in a state in which a second coupling part or portion of the loop pipe is coupled to the discharge pipe. 
     Referring to  FIGS. 5 to 8 , the cover pipe  162   a  may extend from a front surface of the second discharge muffler  168   b  disposed or provided at the frontmost position of the discharge cover assembly  160  to allow the refrigerant discharged to the second discharge space  160   b  to be discharged to the outside of the second discharge space  160   b.    
     The loop pipe  500  may be connected to the cover pipe  162   a  and the discharge pipe  105  to allow the refrigerant to be discharged to the outside of the compressor  10 . 
     The connection structure of the loop pipe  500  may include a first coupling part or portion  510  that couples one or a first end of the loop pipe  500  to the cover pipe  162   a  and a second coupling part or portion or portion  550  that couples the other or a second end of the loop pipe  500  to the discharge pipe  105 . The first coupling part  510  and the second coupling part  550  may be defined as a coupling member. 
     The second coupling part  550  may have the same structure as the first coupling part  510 . Thus, hereinafter, only the structure and coupling method of the first coupling part  510  will be described as an example. 
     The first coupling part  510  may include a connection member  520  having one or a first end inserted into the loop pipe  500  and the other or a second end inserted into the cover pipe  162   a . The connection member  520  may include an insertion part or portion  521  inserted into the loop pipe  500 . A stopper  522  may protrude from an outer circumferential surface of the insertion part  521 , and the stopper  522  may be disposed or provided at a point which is spaced a predetermined distance from an end of the insertion part  521 . The stopper  522  may restrict insertion of the insertion part  521  in a state in which the insertion part  521  is inserted by a predetermined length when the insertion part  521  is inserted into the loop pipe  500 . 
     The stopper  522  may protrude from the outer circumferential surface of the insertion part  521 . The stopper  522  may be continuously disposed or provided in a circumferential direction of the insertion part  521 , or a plurality of stoppers  522  may be disposed or provided to be spaced apart from each other in a circumferential direction of the connection member  520 . 
     A separation prevention protrusion  523  may protrude from the outer circumferential surface of the insertion part  521  to prevent the insertion part  521  from being separated from the loop pipe  500  in the state in which the insertion part  521  is inserted into the loop pipe  500 . A protrusion accommodation groove  504  that accommodates the separation prevention protrusion  523  may be defined in an inner circumferential surface of the loop pipe  500 . Each of the separation prevention protrusion  523  and the protrusion accommodation groove  504  may be formed in a continuous band shape, like the stopper  522 , or a plurality of protrusions and a plurality of accommodation grooves may be disposed or provided to be spaced apart from each other in the circumferential direction. A plurality of the separation prevention protrusion  523  may be provided in a longitudinal direction of the insertion part  521  to effectively prevent the insertion part  521  from being separated from the loop pipe  500 . 
     The first coupling part  510  may further include a pipe cover  540  that surrounds a portion of an outer circumferential surface of the loop pipe  500 , in which the connection member  520  is inserted, and a portion of an outer circumferential surface of the connection member  520 . The pipe cover  540  may be integrated with the loop pipe  500  by insert injection-molding, for example, in a state in which the insertion part  521  is inserted into the loop pipe  500 . Although not limited thereto, each of the loop pipe  500  and the pipe cover  540  may be made of a nylon material. 
     The pipe cover  540  integrated with the loop pipe  500  by the insert injection-molding may support a portion of the loop pipe  500  as well as a portion of the connection member  520 . That is, the pipe cover  540  may include a first cover  542  that covers the loop pipe  500  and a second cover  544  that extends from the first cover  542  to cover the connection member  520 . 
     The first cover  542  may have an outer diameter greater than an outer diameter of the second cover  544 . That is, the pipe cover  540  may be stepped. A stepped surface provided on the pipe cover  540  may be configured so that the connection member  520  may be inserted into the cover pipe  162   a  until an end of the cover pipe  162   a  is closely attached to the stepped surface. That is, the stepped surface may limit a length by which the connection member  520  may be inserted into the cover pipe  162   a.    
     A hole  502 , into which a portion of the pipe cover  540  may be accommodated, may be defined in the loop pipe  500  to prevent the insert-injection-molded pipe cover  540  from being separated from the loop pipe  500 . The hole  502  may be defined in or at a point which is spaced apart from an end of the loop pipe  500 . That is, a molding solution for molding the pipe cover  540  may be filled into the hole  502  during the insert injection-molding, and then, the pipe cover  540  may not be separated from the loop pipe  500  after the injection molding. Also, a plurality of the hole  502  may be provided, which may be spaced apart from each other in the circumferential direction of the loop pipe  500 . In addition, the plurality of holes  502  may be provided in a longitudinal direction of the loop pipe  500 . 
     If the plurality of the hole  502  is provided in the circumferential direction of the loop pipe  500 , when a rotational force is applied to the pipe cover  540 , a portion corresponding to the molding solution filled into the hole  502  may act as rotational resistance to prevent the pipe cover  540  from rotating with respect to the loop pipe  500 . 
     The cover pipe  162   a  may include a connection member coupling part or portion  162   b  into which the connection member  520  may be inserted. The connection member  520  may further include a coupling part or portion  526  to be coupled to the connection member coupling part  162   b.    
     The coupling part  526  may further extend from the end of the insertion part  521  and have an outer diameter greater than an outer diameter of the insertion part  521 . The stopper  522  may be disposed or provided at a point which is spaced apart from the coupling part  526 . The second cover  544  constituting or forming the pipe cover  540  may have a thickness corresponding to a distance from the outer circumferential surface of the insertion part  521  to an inner circumferential surface of the connection member coupling part  162   b  and surround the connection member  522  between the stopper  522  and the coupling part  526 . Also, the first cover  542  of the pipe cover  540  may surround the stopper  522 . 
     As the second cover  544  is disposed or provided between the stopper  522  and the coupling part  526 , a phenomenon in which the connection member  520  is separated from the pipe cover  540  may be prevented. The outer circumferential surface of the connection member  520 , on which the second cover  544  may be disposed or provided, that is, the outer circumferential surface of the connection member  520 , which corresponds between the stopper  522  and the coupling part  526 , may be defined as a cover seating part or seat  524 . The cover seating part  524  may have an outer diameter equal to or less than the outer diameter of the insertion part  521 . As the cover seating part  524  has the outer diameter less than the outer diameter of the insertion part  521 , a contact area between the stopper  522  and the second cover  544  in the radial direction and the circumferential direction may increase, and thus, the connection member  520  may be stably fixed to the pipe cover  540 . 
     An accommodation groove  528  that accommodates an end  545  of the pipe cover  540  may be defined in the coupling part  526 . The accommodation groove  528  may be recessed by a predetermined depth from a rear surface of the coupling part  526  toward the front surface of the coupling part  526 . As the end  545  of the pipe cover  540  is accommodated into the accommodation groove  528  of the coupling part  526 , a phenomenon in which an end of the second cover  544  is spread in the radial direction may be prevented. 
     A sealing member seating groove  527  having a ring shape and recessed by a predetermined depth in the circumferential direction may be defined in the coupling part  526 . A sealing member  530  may be fitted into the sealing member seating groove  527 . The sealing member  530  may be, for example, an O-ring. 
     As illustrated in  FIG. 7 , in the state in which the coupling part  526  is accommodated in the connection member coupling part  162   b , the connection member coupling part  162  may be reduced in diameter by a caulking process, for example. That is, as the connection member coupling part  162   b  is reduced in diameter by the caulking process, the inner circumferential surface of the connection member coupling part  162   b  may press the sealing member  530 . As described above, the inner circumferential surface of the connection member coupling part  162   b  may press the outer circumferential surface of the coupling part  526  in the state of coming into contact with the outer circumferential surface of the coupling part  526  and thus be closely attached and coupled to the outer circumferential surface of the coupling part  526 . 
     The coupling part  526  may have an outer diameter less than an outer diameter of the connection member coupling part  162   b  before the caulking process so that the coupling part  526  may be easily inserted into the connection member coupling part  162   b . Also, the second cover  544  may have an outer diameter less than the outer diameter of the coupling part  526  to prevent the second cover  544  from interfering with the connection member coupling part  162   b  while the coupling part  526  is inserted into the connection member coupling part  162   b . Thus, the second cover  544  may be prevented from being damaged while the coupling part  526  and the connection member coupling part  162   b  are coupled to each other. 
     The connection member  520  may be made of a steel material so that the coupling part  526  and the connection member coupling part  162   b  may be firmly coupled to each other, and the coupling part  526  prevented from being damaged during the caulking process. As each of the connection member  520  and the cover pipe  162   a  may be made of the steel material, a contact surface between the connection member  520  and the cover pipe  162   a  may increase in frictional force after the caulking process is completed, and thus, the connection member  520  may be stably coupled to the cover pipe  162   a  without being easily separated from the cover pipe  162   a . Further, a phenomenon in which the refrigerant leaks between the connection member  520  and the cover pipe  162   a  may be prevented. 
     Also, according to an embodiment, as the contact surface between the connection member  520  and the cover pipe  162   a  increase in frictional force, it is sufficient to provide only a single sealing member  530  on the outer circumferential surface of the coupling part  526 . Thus, as each of the coupling part  526  and the connection member coupling part  162   b  is capable of being designed to have a short length, a space within the shell  101 , which is occupied by the first coupling part  510 , may be reduced. Also, as the space within the shell  101 , which is occupied by the first coupling part  510 , is reduced, an increase in volume of the shell  101  may be minimized. 
     Hereinafter, a process of coupling the loop pipe  500  to the cover pipe  162   a  by the first coupling part  510  will be described hereinafter. 
     First, the insertion part  521  constituting or forming a portion of the connection member  520  may be inserted into the loop pipe  500 . The insertion part  521  may be inserted into the loop pipe  500  until the stopper  522  comes into contact with an end of the loop pipe  500 . 
     The pipe cover  540  may be molded to surround a portion of the loop pipe  500  and a portion of the connection member  520  through the insert injection molding in the state in which the insertion part  521  is inserted into the loop pipe  500 . Then, the sealing member  530  may be coupled to the sealing member seating groove  527  defined in the outer circumferential surface of the coupling part  526 . 
     Next, the coupling part  526  may be inserted into the connection member coupling part  162   b . The coupling part  526  may be inserted into the connection member coupling part  162   b  until an end of the connection member coupling part  162   b  comes into contact with the stepped surface of the pipe cover  540 . Finally, the caulking process through which the connection member coupling part  162   b  may be reduced in diameter may be performed so that the coupling part  526  and the connection member coupling part  162   b  may be firmly attached to each other. 
     According to the above-described process, the loop pipe  500  may have one end stably coupled to the cover pipe  162   a  and the other end stably coupled to the discharge pipe  105 . 
     According to embodiments disclosed herein, the coupling part that couples the guide pipe to the cover discharge part or the discharge pipe may include the connection member made of the steel material, and the cover discharge part or the discharge pipe may be made of the steel material to prevent the connection member from being damaged while the connection member is coupled to the discharge pipe. When the damage to the connection member is prevented, it may prevent the refrigerant from leaking through the connection portion between the connection member and the cover discharge part or between the connection member and the discharge pipe. 
     Also, according to embodiments disclosed herein, as the connection member may be made of the steel material, and the cover discharge part or the discharge pipe is made of the steel material, the contact surface between the connection member and the cover discharge part or between the connection member and the discharge pipe may increase in frictional force during the caulking process to effectively prevent the refrigerant from leaking. After the caulking process is completed, as the contact surface between the connection member and the cover discharge part increases in frictional force, one sealing member may be disposed on the circumference of the connection member. Thus, as the connection member is reduced in length, and the cover discharge part is reduced in length, it may prevent the space, in which the connection member and the cover discharge part are disposed, from increasing within the shell, and thus, to prevent the shell from increasing in size. 
     Also, according to embodiments disclosed herein, as the coupling part may include the connection member connected to the guide pipe and the cover discharge part surrounding the guide pipe and the connection member, and a portion of the cover discharge part may be inserted into the guide pipe, the cover discharge part may be prevented from being separated from the guide pipe and from rotating with respect to the guide pipe. Also, as the connection member may include the stopper that limits a depth by which the connection member may be inserted into the guide pipe and the coupling part to be coupled to the cover discharge part, and a portion of the pipe cover may be disposed or provided between the stopper and the coupling part, the connection member may be prevented from being separated from the pipe cover. 
     Embodiments disclosed herein provide a linear compressor in which damage to a guide pipe through which a compressed refrigerant flows may be prevented while the guide pipe is connected to a discharge cover and a discharge pipe. Embodiments disclosed herein further provide a linear compressor in which a refrigerant may be prevented from leaking through connection portions between a guide pipe and a discharge cover and between the guide pipe and a discharge pipe. 
     Embodiments disclosed herein also provide a linear compressor in which a guide pipe may be prevented from being separated from a discharge cover and a discharge pipe after the guide pipe is connected to the discharge cover and the discharge pipe. Embodiments disclosed herein additionally provide a linear compressor in which a number of sealing member or seal used for connection portions between a guide pipe and a discharge cover and between the guide pipe and a discharge pipe may be reduced. Embodiments disclosed herein provide a linear compressor a total length of which may be prevented from increasing due to an increase in length of a cover discharge part connected to a guide pipe. 
     Embodiments disclosed herein provide a linear compressor that may include a shell; a compressor body accommodated in the shell to compress a refrigerant; a discharge cover assembly through which the refrigerant compressed in the compressor body may be discharged; a cover pipe that extends from the discharge cover assembly to discharge the refrigerant discharged into the discharge cover assembly to an outside of the discharge cover assembly; a discharge pipe coupled to the shell to discharge the refrigerant flowing along the cover pipe to an outside of the shell; a loop pipe having one or a first end connected to the cover pipe and the other or a second end connected to the discharge pipe; and a coupling member that respectively couples both ends of the loop pipe to the cover pipe and the discharge pipe. The coupling member may include a connection member, one or a first portion of which may be inserted into the loop pipe and the other or a second portion of which may be inserted into the discharge pipe or the cover pipe, the connection member being formed of a steel material. At least one of the discharge pipe or the cover pipe may be formed of a steel material. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description. Other features will be apparent from the description and drawings, and from the claims. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.