Patent Publication Number: US-2006017342-A1

Title: Rotor and compressor having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims the benefit of Korean Patent Application No. 2004-56455, filed on Jul. 20, 2004 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 compressor, and, more particularly, to a compressor having a rotor which electromagnetically interacts with a stator, that produces a magnetic field, and implements rotating motion.  
      2. Description of the Related Art  
      In general, a compressor is a device to suction a refrigerant into a hermetic space to compress it and discharge the compressed refrigerant to the outside. Such a compressor comprises a compressing unit to compress the refrigerant and a driving unit to drive the compressing unit.  
      The compressing unit is disposed inside a hermetic casing defining the hermetic space, and includes a cylinder block defining a compression chamber and a piston reciprocating inside the compression chamber. A cylinder head is coupled at one side of the cylinder block and is formed with a suction chamber and a discharge chamber, which communicate with the outside.  
      The driving unit includes a stator producing a magnetic field, a rotor adapted to implement rotating motion by electromagnetically interacting with the stator, a motor having a rotating shaft press-fitted in a hollow portion of the rotor so as to rotate simultaneously with the rotor, and a connecting rod connected to the rotating shaft and adapted to convert rotating motion into rectilinear reciprocating motion so as to move the piston forward or backward.  
      The rotor, in turn, includes a plurality of laminates stacked around the rotating shaft to form a core, a pair of end plates to support upper and lower ends of the core of the laminates, and magnets arranged around the core of the laminates. In order to secure the end plates to the core of the laminates, fastening members penetrate through the end plates and the core of the laminates. A cylindrical member is provided to surround the magnets in order to fixedly maintain the magnets relative to the core of the laminates.  
      However, the conventional compressor configured as stated above has a problem in that the cylindrical member must be present in the rotor, resulting in a complicated manufacturing process and high manufacturing cost.  
      The cylindrical member used to fixedly maintain the magnets, further, causes the stator, that produces magnetic flux, to be more distant from the core, resulting in deterioration in the output efficiency of the motor.  
     SUMMARY OF THE INVENTION  
      The present invention has been made in view of the above mentioned problems, and an aspect of the invention is to provide a compressor which can permit magnets to be easily and securely affixed to a rotor and can minimize a distance between a rotor core and a stator, thereby achieving an improved output efficiency of the compressor.  
      In accordance with an aspect, the present invention provides a compressor comprising a rotating shaft and a rotor adapted to rotate simultaneously rotate with the rotating shaft and electromagnetically interact with a stator producing a magnetic field, wherein the rotor includes: a core formed as a stack of a plurality of laminates; a plurality of magnets arranged on an outer circumference of the core to be circumferentially spaced apart from one another; and hooks provided on the core between the respective magnets so as to prevent radial separation of the magnets.  
      The hooks may be integrally formed with the core.  
      A respective one of the hooks may include: a protruding portion extending outward from the core in a radial direction; and a support portion extending from a distal end of the protruding portion in a circumferential direction and serving to support the magnets relative to the core.  
      A respective one of the magnets may be formed at opposite ends thereof with coupling recesses to correspond to the support portions of the hooks so that the magnets are coupled with the hooks to define a cylindrical form.  
      The rotor may further include end plates provided at opposite ends of the core in order to axially support the core and the magnets.  
      The core and the end plates may be fixed to one another via rivets penetrating therethrough.  
      Additional aspects and/or 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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the invention will become apparent and more easily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
       FIG. 1  is a sectional view illustrating the overall structure of a compressor in accordance with the present invention;  
       FIG. 2  is an exploded perspective view illustrating a rotor provided in the compressor in accordance with the present invention;  
       FIG. 3  is a sectional view taken along line A-A shown in  FIG. 2 ;  
       FIG. 4  is a plan view of a core shown in  FIG. 2 ; and  
       FIG. 5  is a plan view of magnets shown in  FIG. 2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.  
       FIG. 1  is a sectional view illustrating the overall structure of a hermetic compressor in accordance with the present invention.  
      Referring to  FIG. 1 , the hermetic compressor of the present invention comprises a compressing unit  20  disposed inside a hermetic casing  10  defining a hermetic space to compress a refrigerant, and a driving unit  30  to drive the compressing unit  20 .  
      The compressing unit  20  includes a cylinder block  21  internally defining a compression chamber  21   a,  and a piston  22  reciprocating inside the compression chamber  21   a  so as to compress the refrigerant. A cylinder head  23  is coupled to one side of the cylinder block  21 . The cylinder head  23  internally defines a suction chamber  23   a  and a discharge chamber  23   b.  A valve unit  24  is interposed between the cylinder block  21  and the cylinder head  23  so as to control introduction and discharge of the refrigerant.  
      The driving unit  30  operates to reciprocate the piston  22 , thereby permitting the refrigerant to be compressed inside the compressing unit  20 . The driving unit  30  includes a stator  31  producing a magnetic field, a rotor  40  inwardly spaced apart from the stator  31  to electromagnetically interact with the stator  31 , a rotating shaft  32  press-fitted in the center of the rotor  40  to rotate simultaneously with the rotor  40 , and a connecting rod  33  connected to the rotating shaft  32  and adapted to convert rotating motion into rectilinear reciprocating motion so as to move the piston  22  forward or backward.  
      Now, the rotor  40  according to the present invention will be explained in more detail with reference to  FIGS. 2 and 3 .  FIG. 2  is an exploded perspective view of the rotor  40  and  FIG. 3  is a sectional view taken along line A-A shown in  FIG. 2 .  
      Referring to  FIGS. 2 and 3 , the rotor  40  according to the present invention includes a core  41  formed as a plurality of laminates  41 ′ are vertically stacked one above another, and magnets  43  arranged on the outer circumference of the core  41 .  
      A plurality of the magnets  43  are arranged in alternating polarity, and are spaced apart from one another in a circumferential direction in order to avoid magnetic interference therebetween.  
      An upper end plate  44  and a lower end plate  45  are provided at upper and lower sides of the core  41  and are adapted to axially support the core  41  and the magnets  43 . The respective laminates  41 ′ and the end plates  44  and  45  are fixedly maintained relative to one another via rivets  46  penetrating therethrough.  
      The core  41  is integrally provided at the outer circumference thereof with hooks  42 . The respective hooks  42  are interposed between the respective magnets  43  in order to prevent separation of the magnets  43  in an outward direction.  
      Referring to  FIG. 4 , a respective one of the hooks  42  has a protruding portion  42   a  extending outward from the core  41  in a radial direction, and a support portion  42   b  extending from a distal end of the protruding portion  42   a  in a circumferential direction. The protruding portion  42   a  serves to keep the magnets  43  spaced apart from one another, and the support portion  42   b  serves to prevent the magnets  43  from being separated in a radial direction.  
      Referring to  FIG. 5  illustrating the magnets  43 , a respective one of the magnets  43  has coupling recesses  43   a  defined at opposite ends thereof, respectively, to correspond to the support portions  42   b  of the adjacent hooks  42 . The coupling recesses  43   a  permit the magnets  43  to be spaced apart from one another while defining spaces S each having the same shape as that of the respective hooks  42 . In this way, the magnets  43  and the hooks  42  are alternately coupled to one another to thereby define a cylindrical form.  
      Now, the assembly process and operational effects of the rotor  40  provided in the hermetic compressor according to the present invention will be explained.  
      First, the rivets  46  are successively screwed through the upper end plate  44  and the plurality of laminates  41 ′. Then, the magnets  43  are affixed to the outer circumference of the core  41  formed as the laminates  41 ′ are vertically stacked one above another. In this case, the magnets  43  are inserted in respective spaced defined between the hooks  42  and the outer circumference of the core  41  so that they are circumferentially arranged in alternating polarity.  
      Successively, the lower end plate  45  is fastened to the rivets  46 , and then lower ends of the rivets  46  are caulked, permitting the magnets  43  to be securely affixed around the core  41 .  
      In this way, since the magnets  43  are able to be securely affixed around the core  41  via the end plates  44  and  45  and the hooks  42 , the rotor  40  of the compressor according to the present invention has no need for a separate cylindrical member used in a conventional compressor in order to fixedly surround the outer circumference of the magnets  43 .  
      As a result, a distance between the core  41  of the rotor  40  and the stator  31  producing magnetic flux can be minimized, resulting in an improved driving efficiency of the compressor.  
      As is apparent from the above description, the present invention provides a compressor having a rotor in which a plurality of magnets can be securely affixed around a rotor core via hooks formed at the outer circumference of the core.  
      Such fixation of the magnets eliminates the need for a separate cylindrical member conventionally used to surround the outer circumference of the magnets, resulting in a reduction in the number of parts and improving productivity of the compressor.  
      Further, the elimination of the conventional cylindrical member has the effect of minimizing a distance between a stator and the rotor core, resulting in an improved driving efficiency of the compressor.  
      Although an embodiment of the present invention has been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.