Abstract:
A linear compressor comprises an external casing forming a compressing chamber, an outer core disposed in the external casing, an inner core assembly disposed inside of the outer core interacting with the outer core, and wherein the inner core assembly comprises an inner core, an upper cover combined to an upper part of the inner core, and a bottom supporting part combined to a bottom part of the inner core. With this configuration, the linear compressor provides a capability of simplifying an inner core assembly, thereby reducing the manufacturing cost.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Patent Application No. 2003-39679, filed on Jun. 19, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a linear compressor and more particularly a linear compressor having an improved assembling structure of an inner core assembly. 
   2. Description of the Related Art 
   In general, a conventional linear compressor comprises a casing, a mover provided in the casing and reciprocating by an interaction of an inner core and an outer core, a compressing part compressing and discharging a refrigerant, and a linear motor generating a, driving force of the inner and outer cores. 
   The conventional linear compressor operates in the following sequence. 
   When power is supplied to the compressor while the compressor is in a stop state, current is applied to winding coils at an opening part of the outer core, thereby generating a rotational magnetic flux at the inner core and the outer core. The magnetic flux interacts with a magnetic field formed by a magnet to reciprocate a piston, and thereby suctioning and discharging the refrigerant after compressing. 
   Korean Patent No. 0374837 discloses a linear motor for such a conventional compressor comprising a stator having an outer core and a cylindrical inner core inserted into the outer core, winding coils combined into the inner core or the outer core, and a mover movably inserted between the outer core and the inner core having a permanent magnet provided therein. 
   The outer core includes a plurality of lamination sheets incorporated into a laminated unit, and is combined to an annular bobbin having coils wounded by an injection-molded insulator. 
   However, it is necessary that the inner core and the outer core provided as a laminated unit are firmly mounted with a simple structure and an easy installation, and thereby reducing the manufacturing costs of the conventional linear motor. 
   Also, it is necessary to prevent a decrease in the efficiency of the linear motor due to an eddy current loss generated when material having low electrical resistivity for the inner core of the conventional linear motor. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an aspect of the present invention to provide a linear compressor which is capable of simplifying an inner core assembly, thereby reducing the manufacturing cost. 
   Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part, will be obvious from the description, or may be learned by practice of the invention. 
   The foregoing and/or other aspects of the present invention are achieved by providing a linear compressor comprising an external casing forming a compressing chamber, an outer core disposed in the external casing, an inner core assembly disposed inside of the outer core interacting with the outer core, wherein the inner core assembly comprising an inner core, an upper cover combined to an upper part of the inner core, and a bottom supporting part combined to a bottom part of the inner core. 
   According to an aspect of the invention, the inner core comprising a plurality of core blocks provided by stacking a plurality of core steel plates made by punching thin steel plates, wherein the plurality of core blocks are circumferentially arranged around the inner core at regular intervals. 
   According to an aspect of the invention, each core steel plate comprising an upper hook in an upper part thereof, and a bottom hook in a bottom part, and the upper cover comprising an upper recess to engage with the upper hook and the bottom supporting part comprising a bottom recess to engage with the bottom hook. 
   According to an aspect of the invention, the upper cover and the bottom supporting part are connected to each other by a connection member, which stands erect toward the bottom supporting part. 
   According to an aspect of the invention, the connection member comprising a bolt or a rivet disposed between the plurality of core blocks. 
   According to an aspect of the invention, the upper cover and the bottom supporting part are provided as a single unit, and the plurality of core blocks have connection supporting parts standing erect toward the bottom supporting part between the core blocks, forming a single unit with the upper cover and the bottom supporting part. 
   According to an aspect of the invention, the inner core is made by stacking a plurality of core steel plates made by punching thin steel plates. 
   According to an aspect of the invention, the upper part of each of the core steel plates comprising an upper hook protruding upward, and the bottom supporting part of each of the core steel plates has a bottom hook protruding downward, and the upper cover comprising an upper recess to engage with the upper hook and the bottom supporting part has a bottom recess to engage with the bottom hook, wherein an area where the upper hook is engaged with the upper recess, and an area where the bottom hook is engaged with the bottom recess are welded to each other. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a sectional view of a linear compressor according to a first embodiment of the present invention; 
       FIG. 2  is a plan view of an inner core assembly of the linear compressor of  FIG. 1 ; 
       FIG. 3  a sectional view of the inner core assembly, taken along a line III-III of  FIG. 2 ; 
       FIG. 4  is a plan view of the inner core assembly shown in  FIG. 2 , without an upper cover; 
       FIG. 5  is a plan view of the inner core assembly according to a second embodiment of the present invention; 
       FIG. 6  is a sectional view of an inner core assembly, taken along a line VI-VI of  FIG. 5 ; 
       FIG. 7  is a plan view of an inner core assembly according to a third embodiment of the present invention; 
       FIG. 8  is a sectional view of the inner core assembly, taken along a line VIII-VIII of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
   In  FIG. 1 , a linear compressor according to a first embodiment of the present invention comprising an external casing  10 , a mover  20  provided in the external casing  10  and reciprocating by an interaction of an outer core  40  (to be described later) and an inner core  61  (to be described later), and a compressing part  30  suctioning and discharging the refrigerant after compressing. 
   The external casing  10  is closed to the outside with an upper casing  11  and a bottom casing  12  welded to each other at an end of the upper casing  11  and an end of the bottom casing  12 . In  FIG. 1 , the end of the bottom casing  12  is welded on the end of the upper casing  11 . 
   The mover  20  comprising a main frame  22 , an inner core assembly  60  disposed inside the main frame  22 , and a cylinder-shaped magnet  26  disposed in an opening of the inner core assembly  60 . An inner core  61  of the inner core assembly  60  is radially disposed to the inner circumference of the main frame  22 . 
   In  FIGS. 2-4 , the inner core assembly  60  has the cylinder-shaped inner core  61 , an upper cover  70  combined to an upper side of the inner core  61 , a bottom supporting part  80  combined to a bottom of the inner core  61 . The upper cover  70  is combined with the bottom supporting part  80  by at least one connection member  90 . The inner core  61  comprising a plurality of core blocks  62  radially arranged at regular intervals to form a cylinder shape. Each of the core blocks  62  is formed by stacking a plurality of core steel plates  63  made by punching a thin steel plate and welding the stack of core steel plates  63 . 
   In upper parts of the plurality of core steel plates  63  forming the core blocks  62 , upper hooks  64  are protruded upward to be combined to the upper cover  70 , and bottom hooks  65  are protruded downward to be combined to the bottom supporting part  80  in a bottom of the plurality of core steel plates  63 . 
   An upper recess  71  is formed in an upper part of the inner core  61  to engage with the upper hooks  64 , to combine the upper cover  70  to the upper part of the inner core  61 . Thus, the upper cover  70  can support the upper part of the inner core  61 . 
   In the upper cover  70 , a plurality of first connecting holes  72  are circumferentially arranged around the inner core  61 . 
   A bottom recess  81  is formed in a bottom of the inner core  61  engaged with the bottom hooks  65  and to combine the bottom supporting part  80  to the bottom of the inner core  61 . 
   In the bottom supporting part  80 , a plurality of second connecting holes  82  are circumferentially arranged around the inner core  61  wherein the connection member  90  connecting the upper cover  70  and the bottom supporting part  80  is engaged. 
   The connection member  90  comprising a bolt or a rivet, and passing through the first connecting hole  72  of the upper cover  70  and through a space formed between the plurality of core blocks  62 , and is then inserted into the second connecting hole  82  of the bottom supporting part  80 . Thus, the upper cover  70  and the bottom supporting part  80  are stably connected. Here, the connection member  90  is vertically positioned to the bottom supporting part  80 . 
   In  FIG. 1  the compressing part  30  comprising a cylinder block  34  forming a compressing chamber  32  while supporting a bottom of the outer core  40 , a piston  36  reciprocating in the compressing chamber  32 , and a cylinder head  38  provided in a bottom area of the cylinder block  34  and having valves for a refrigerant. 
   The cylinder-shaped outer core  40  is provided on an outside the mover  20 , with a predetermined gap relative to the magnet  26 . An opening of the outer core  40  comprising a plurality of core steel plates (not shown) stacked each having annular coils  42  therein. 
   The outer core  40  comprising a bottom part supported by the cylinder block  34  and an upper part supported by a supporting block  44 . On an upper part of the supporting block  44 , a resonant spring (not shown) accelerating the reciprocating movement of the piston  36  is combined by a plurality of shaft members  52 . 
   The linear compressor according to the present invention is operated as follows. 
   When power is supplied to the linear compressor in a stop state, current is applied to the coils  42  in the opening of the outer core  40 . Then, a rotational magnetic flux is generated in the outer core  40  and the inner core  61  to thereby generate magnetic flux to interact with a magnetic field of the magnet  26 . Thus, the piston reciprocates up and down so as to suction, compress and discharge the refrigerant of the compressing chamber  32 . 
   According to the first embodiment of the present invention, the upper cover  70  and the bottom supporting part  80  are individually provided and connected to each other by at least one connection member  90 . According to a second embodiment as shown in  FIGS. 5 and 6 , the upper cover  70  and the bottom supporting part  80  is provided as a single unit by injection molding of resin or die casting of aluminum. Accordingly, unlike the connection member  90  provided between the plurality of the core blocks  62  according to the first embodiment of the present invention, connection supporting parts  95  are provided between the plurality of the core blocks  62   a  in a vertical direction to a bottom supporting part  80   a  as shown in  FIG. 5 , forming a single unit with an upper cover  70   a  and the bottom supporting part  80   a.    
   The inner core  61   a  comprises the plurality of core blocks  62  and  62   a  according to the first and the second embodiments of the present invention. In  FIGS. 7 and 8 , an inner core  61   b  can be made by radially stacking core steel plates  63   a  made by punching thin steel plates with an upper cover  70   b  combined to an upper part of the inner core  61   b  and a bottom supporting part  80   b  combined to a bottom part thereof. That is, as parts of the inner core  61   b , an upper hook  64   b  formed in the plurality of core steel plates  63   a  and an upper recess  71   b  of the upper cover  70   b  are engaged to each other, and thus the upper cover  70   b  is connected to the upper part of the inner core  61   b , and a bottom hook  65   b  formed in a plurality of the core steel plates  63   a  and a bottom recess  81   b  are engaged to each other, so that the bottom supporting part  80   b  is connected to the bottom part of the inner core  61   b.    
   According to a third embodiment of the present invention, connecting areas of the upper hook  64   b  and the upper recess  71   b  and of the bottom hook  65   b  and the bottom recess  81   b  are respectively welded, unlike the first and second embodiments. 
   In the linear compressor according to the third embodiment of the present invention, the inner core assembly can be manufactured simply, thereby decreasing the manufacturing cost. 
   Also, the inner core assembly with such an assembling structure minimizes eddy current, thereby increasing the efficiency of the linear motor. 
   Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.