Abstract:
A reciprocating motor includes a pair of stators and a cylindrical magnet formed as a single body and disposed between the stators, for linearly reciprocating. Accordingly, it allows facilitating a job of manufacturing and installing the magnet, so that productivity can be improved.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a reciprocating motor, and more particularly, to a reciprocating motor which enables to improve productivity and assembling of a magnet. 
   2. Description of the Background Art 
   In general, a reciprocating motor has a magnetic flux in a plane form, and a movable unit disposed between an outer stator and an inner stator linearly reciprocates according to variation of the magnetic flux. 
   As shown in  FIGS. 1 and 2 , the conventional reciprocating motor includes an outer stator  11  having a cylindrical shape by radially stacking a plurality of lamination sheets  14  to an outer side of a winding coil  15 , an inner stator  12  disposed in an inner circumference of the outer stator  11  at a certain air gap from an inner circumferential surface of the outer stator  11  and having a cylindrical shape by radially stacking a plurality of lamination sheets  13 , and a movable unit  20  disposed between the outer stator  11  and the inner stator  12  and linearly reciprocating. 
   The movable unit  20  includes a magnet frame  21  disposed between the outer stator  11  and the inner stator  12 , a plurality of magnets  22  installed along the circumference of the magnet frame  21 , and a retainer ring  23  for fixing the magnets  22  on the magnet frame  21 . 
   As shown in  FIG. 3 , the magnet frame  21  is formed as a cylindrical shape and made of stainless steel (SUS)-based materials. A plurality of grooves  21   a  having a predetermined depth are respectively recessed along an outer circumference of the magnet frame  21  so as to mount the magnets  21   a  therein. 
   The retainer ring  23  is made of thin metallic materials, and compresses each of outer circumferences of a plurality of magnets  22  to thereby fix a plurality of magnets  22  on an outer circumferential surface of the magnet frame  21 . In addition, a plurality of slits  23   a  for interrupting an eddy current are formed at the outer circumferential surface of the retainer ring  23 . 
   The movable unit  20  is assembled as follows. While a plurality of magnets  22  are being adhered to the grooves  21   a  recessed in the outer circumferential surface of the magnet frame  21  by an adhesive, each of them is insertedly fixed to the grooves  21   a . Then, the retainer ring  23  is inserted to encompass the outer circumference of the magnets  22 , and both ends of the retainer ring  23  are bent to fix the magnets  22 . 
   In the conventional reciprocating motor, when an external power is applied to the winding coil  15 , magnetic flux is formed around the winding coil  15 . The flux forms a kind of closed loop by flowing to the inner stator  12  along one path of the outer stator  11  and flowing to another path of the outer stator  11 . And, as the magnets  22  are pushed and pulled according to a direction of the flux, the magnet frame  21  linearly reciprocates. 
   However, in the conventional reciprocating motor, because a plurality of the magnets  22  should be separately installed at the magnet frame  21  after they are individually fabricated, the assembly process of the magnets  22  is complicated, thereby lowering productivity of products. 
   In addition, in order to maintain regular intervals between a plurality of magnets  22  attached to the magnet frame  21 , the magnets  22  are fixed via the retainer ring  23 . Therefore, the number of parts is increased because of the use of the retainer ring  23  to thereby increase a manufacturing cost and complicate the assembly process. 
   SUMMARY OF THE INVENTION 
   Therefore, an object of the present invention is to provide a reciprocating motor capable of improving productivity of a product and reducing the cost by integrally manufacturing a magnet in a cylindrical shape and simplifying the manufacturing process of the magnet and the assembly process of the magnet. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a reciprocating motor, comprising a pair of stators, and a cylindrical magnet formed as a single body and disposed between the stators, for linearly reciprocating, wherein the magnet is integrally formed in a cylindrical shape. 
   In addition, at least one slit for interrupting an eddy current is formed at an outer circumference of the magnet in a direction that the magnet linearly reciprocates. 
   The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
       FIG. 1  is a sectional view showing the conventional reciprocating motor; 
       FIG. 2  is an enlarged sectional view showing a movable unit of the reciprocating motor of  FIG. 1 ; 
       FIG. 3  is an exploded perspective view showing the movable unit of the reciprocating motor of  FIG. 1 ; 
       FIG. 4  is a sectional view showing a reciprocating motor in accordance with one embodiment of the present invention; 
       FIG. 5  is an enlarged sectional view showing a movable unit of the reciprocating motor of  FIG. 4 ; 
       FIG. 6  is an exploded perspective view showing the movable unit of the reciprocating motor of  FIG. 4 ; and 
       FIG. 7  is an exploded perspective view showing a movable unit of a reciprocating motor in accordance with another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter, reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
   As shown in  FIGS. 4 and 5 , a reciprocating motor in accordance with the present invention includes an outer stator  111  having a cylindrical shape by radially stacking a plurality of lamination sheets  114  on an outer side of a winding coil  115 , an inner stator  112  disposed in an inner circumference of the outer stator  111  at a certain air gap from an inner circumferential surface of the outer stator  111  and having a cylindrical shape by radially stacking a plurality of lamination sheets  113 , and a movable unit  120  disposed between the outer stator  111  and the inner stator  112  and linearly reciprocating. 
   As shown in  FIG. 6 , the movable unit  120  includes a magnet frame  121  disposed between the outer stator  111  and the inner stator  112 , and a cylindrical magnet  122  formed as a single body and installed on an outer circumferential surface of the magnet frame  121 . 
   The magnet frame  121  is formed in a cylindrical shape, and a cylindrical groove  121   a  having a predetermined depth are recessed along an outer circumference of the magnet frame  121  so as to mount the magnet  122  therein. In addition, a plurality of through holes  121   b  are preferably formed around the magnet frame  121  to reduce resistance generated during the movement of the magnet frame  121 . 
   The magnet  122  is insertedly fixed in the groove  121   a , and the magnet  122  can be more stably fixed to the groove  121   a  by interposing an adhesive between the magnet  122  and the groove  121   a.    
   An inner diameter of the magnet  122  is formed to be substantially identical to an outer diameter of the groove  121   a , which is advantageous in stably insertedly fixing the magnet  122  in the groove  121   a . In this case, the magnet  122  is preferably formed with an elastic material. 
   Meanwhile, at least one slit  122   a  is formed in the outer circumference of the magnet  122  in an axial direction of the magnet  122 , i.e. in a direction that the assembly of the magnet frame  121  and the magnet  122  linearly reciprocate, in order to interrupt an eddy current. A length of the slit  122   a  is shorter than a width of the magnet  122  in the direction that the magnet  122  linearly reciprocates, and a plurality of slits are preferably formed in a circumferential direction of the magnet  122  at the same intervals. 
   The slits  122   a  are opened toward one side facing the magnet frame  121  and toward another side opposite to one side facing the magnet frame  121 , respectively. Here, the slits opened to one side of the magnet  122  and the slits opened to another side of the magnet  122  are alternately formed, which is an effective way to maintain the intensity of the magnet  122 . 
   However, not limited to such construction, as shown in  FIG. 7 , all of the slits  122   a  can be opened toward one side facing the magnet frame  121  or toward another side opposite to one side facing the magnet frame  121 . In this case, in order to insertedly fix the magnet  122  to the magnet frame  121   a  easily, the slits  122   a  are preferably opened toward the direction facing the magnet frame  121 . 
   In the reciprocating motor having such construction in accordance with the present invention, the assembly of the movable unit  120  is completed by simply insertedly fixing the cylindrical magnet  122  to the magnet frame  121 . 
   At this time, since the magnet frame  121  is provided with the groove  121   a , the cylindrical magnet  122  is inserted upon the groove  121   a  to be firmly fixed to the groove. 
   In addition, since the slits  122   a  are formed on the outer circumference of the magnet  122 , when the magnet  122  is installed at the magnet frame  121 , the slits  122   a  are spread to a certain degree. Therefore, the magnet  122  can be easily mounted at the magnet frame  121 . 
   In the reciprocating motor in accordance with the present invention, when an external power is applied to the winding coil  115 , magnetic flux is formed around the winding coil  115 . The flux flows forms a kind of closed loop by flowing to the inner stator  112  along one path of the outer stator  111  and flowing to another path of the outer stator  111 . And, as the magnet  122  of the movable unit  120  is pushed and pulled according to a direction of the flux, the magnet  122  linearly reciprocates. At this time, the eddy current is generated in the magnet  122 , but such eddy current is interrupted by the silts  122   a  formed at the magnet  122 . Therefore, a loss caused by the eddy current is prevented. 
   In the reciprocating motor in accordance with the present invention, because a cylindrical magnet formed as a single body is inserted upon a cylindrical magnet frame, in comparison to the conventional reciprocating motor in which a plurality of magnets are individually fabricated and separately fixed into an outer circumference of a magnet frame, the manufacturing process of the magnet and the assembly process of the magnet are simple, thereby improving productivity. 
   In addition, the reciprocating motor in accordance with the present invention is provided with the cylindrical magnet formed in a single body. Accordingly, a separate part for fixing magnets to a magnet frame such as a retainer ring of the conventional art is unnecessary, so that the production cost can be reduced. 
   As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.