Patent Publication Number: US-2007114864-A1

Title: Motor with position-adjustable rotor

Description:
FIELD OF THE INVENTION  
      The present invention relates to a motor with a position-adjustable rotor, and more particularly, to a motor with a position-adjustable rotor capable of adjusting a gap between the rotor and a holder assembly, making ease of the gap adjustment, and thus implementing the same rotor to various motors with different specifications and structures.  
     BACKGROUND OF THE INVENTION  
      In general, a motor is a device that converts electrical energy into mechanical energy to provide a rotational force. Motors are being widely applied to various industrial fields including electric home appliances and industrial machines. For instance, motors can be applied to compressors, which are installed inside cooling appliances such as air conditioners and refrigerators to restore a refrigerant to a liquid, washing machines, vacuum cleaners, optical disk players, and hard disk drivers of computers.  
      A conventional motor will be described with reference to  FIG. 1  hereinafter.  
       FIG. 1  illustrates a sectional view of main parts of a conventional motor  10 . The conventional motor  10  is an oilless type motor. In the conventional motor  10 , holder assemblies  11  are attached individually to a casing (not shown) on both upper and lower sides. Although not illustrated, a stator is affixed to the inside of the casing. A rotor  12  is inserted into the stator (not shown) to be rotatable by having a gap inside the stator (not shown). A rotational shaft  13  passes through a central region of the rotor  12  and is affixed thereto. The rotational shaft  13  is inserted into the holder assemblies  11  to be rotatable by means of the oilless bearings  11   e.    
      The holder assemblies  11  include bearing installation units  11   a  in a central region of the holder assemblies  11 , and the oilless bearings  11   e  elastically supported by respective plate springs  11   b  are installed on the respective bearing installation units  11   a . Each of the bearing covers  11   c  is attached to an exterior portion of each of the bearing installation units  11   a  and shields an inflow of foreign materials. The plate springs  11   b  are firmly fixed by the respective bearing covers  11   c . Spaces that permawicks  11   d  having oil fill individually are formed around the oilless bearings  11   e.    
      In the conventional motor  10 , the rotor  12  and each of the holder assemblies  11  are spaced apart from each other by having a gap therebetween to optimize an electron induction event between the rotor  12  and the stator (not shown) and make the rotor  12  rotate smoothly.  
      However, when the specification or structure of the conventional motor  10  is changed, it may be difficult to maintain an intended gap between the rotor  12  and each of the holder assemblies  11 , and the gap therebetween may not be changed. Therefore, when the specification or structure of the conventional motor  10 , or the gap between the rotor  12  and each of the holder assemblies  11  is changed, another rotor with the different height often needs to be manufactured, and simultaneously, manufacturing costs may increase.  
     SUMMARY OF THE INVENTION  
      It is, therefore, an object of the present invention to provide a motor with a position-adjustable rotor capable of adjusting a gap between the rotor and a holder assembly, making ease of the gap adjustment, and thus implementing substantially the same rotor to various motors having different specifications or structures so as to reduce manufacturing costs.  
      In accordance with a preferred embodiment of the present invention, there is provided a motor with a position-adjustable rotor, wherein a rotational shaft is supported to be rotatable by holder assemblies, the motor including rotor to which the rotational shaft is affixed in a central region, including position adjusting indentations around the rotational shaft, and formed by pressing soft magnetic powder, and position adjusting bushings each inserted into the rotational shaft to be positioned between the rotor and the corresponding holder assembly and including an insertion unit inserted into the corresponding position adjusting indentation and a locking unit supported at the exterior side of the corresponding position adjusting indentation by having different diameters or widths on both sides of the position adjusting bushing, wherein gaps between the rotor and each of the holder assemblies can be adjusted by changing a direction that the position adjusting bushings are inserted into the rotational shaft.  
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:  
       FIG. 1  illustrates a sectional view of main parts of a conventional motor;  
       FIGS. 2A and 2B  illustrate a sectional view of main parts of a motor with a position-adjustable rotor in accordance with an embodiment of the present invention; and  
       FIG. 3  is a sectional view of the motor with a position-adjusted rotor illustrated in  FIGS. 2A and 2B ; and  
       FIG. 4  is a diagram for illustrating the working of the motor with the position-adjustable rotor in accordance with the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that they can be readily implemented by those skilled in the art.  
       FIGS. 2A and 2B  illustrate a sectional view of main parts of a motor  100  with a position-adjustable rotor in accordance with an embodiment of the present invention. The motor  100  with the position-adjustable rotor includes holder assemblies  110 , a rotational shaft  120 , a rotor  130 , position adjusting indentations  131 , and position adjusting bushings  140 . The rotational shaft  120  is supported to be rotatable by the holder assemblies  110 . The rotational shaft  120  is affixed to a central region of the rotor  130 , and is formed by pressing soft magnetic powder to form the position adjusting indentations  131 . Each of the position adjusting bushings  140  changes a direction of an insertion into the rotational shaft  120  so as to be supported at the interior or exterior side of each of the position adjusting indentations  131 . Through this support, the position adjusting bushings  140  can adjust gaps between the rotor  130  and each of the holder assemblies  110 .  
      The holder assemblies  110  include respective bearing installation units  112  in a central region to install oilless bearings  111 , which supply lubricating oil to the rotational shaft  120 , on the respective bearing installation units  112 . Plate springs  113  are installed individually on one portion of each of the oilless bearings  111  exposed by the respective bearing installation units  112 . As a result, the plate springs  113  electrically support the respective oilless bearings  111 . Bearing covers  114  attached individually to an exterior portion of each of the bearing installation units  112  firmly fix the respective plate springs  113 .  
      Each of the holder assemblies  110  includes a space that a permawick  115  containing oil fills around each of the oilless bearings  111  so as to provide the oil to those regions where friction occurs, e.g., a contact region between the rotational shaft  120  and the corresponding oil bearing  111 .  
      The rotational shaft  120  is affixed to the central region of the rotor  130 , and thus rotates with the rotor  130 .  
      The rotor  130  is placed inside a stator (not shown), which is affixed to the inner surface of the casing (not shown), by having a gap inside the stator (not shown), and rotates due to an electron induction event generated by the stator (not shown). The position adjusting indentations  131  are formed around the rotational shaft  120 .  
      The rotor  130  is molded by pressing soft magnetic powder. The soft magnetic powder includes iron-based particles, each coated with a certain material to be electrically insulated from each other.  
      In detail of the formation of the position adjusting indentations  131 , a press molding apparatus includes a molding space formed in a shape substantially the same as the rotor  130 , and the soft magnetic powder is filled into the molding space. A pressing member such as a punch presses the soft magnetic powder to form the position adjusting indentations  131  in the rotor  130 . A lubricant and/or a binder may be added to the soft magnetic powder and pressed together.  
      The rotor  130  includes a three-dimensional soft magnetic composite (SMC) by pressing the soft magnetic powder, and usually has a higher degree of freedom as compared with the conventional rotor  12  (see  FIG. 1 ) obtained by stacking identically shaped silicon steel sheets over each other. As a result of this high degree of structural freedom, different from the conventional stack structure of the rotor  12 , the position adjusting indentations  131  can be formed in the rotor  130 .  
      The position adjusting bushings  140  are inserted into the rotational shaft  120  to be positioned between the rotor  130  and each of the holder assemblies  110 . Each of the position adjusting bushings  140  is formed to have different diameters and widths on both sides, so that gaps between the rotor  130  and each of the holder assemblies  110  can be adjusted by changing the direction that the position adjusting bushings  140  are inserted into the rotational shaft  120 . That is, one portion of each of the position adjusting bushings  140  is formed to have a smaller diameter or width than each of the position adjusting indentations  131 , and as a result, insertion units  141  that can be supported by being inserted into each of the position adjusting indentations  131  are formed. Also, another portion of each of the position adjusting bushings  140  is formed to have a larger diameter or width than each of the position adjusting indentations  131 , and as a result, locking units  142  that can be supported at the exterior side of each of the position adjusting indentations  131  are formed. Therefore, the position adjusting bushings  140  adjust gaps between the rotor  130  and each of the holder assemblies.  
      At the entrance side of each of the position adjusting indentations  131 , the rotor  130  includes locking unit installation openings  132  into which the respective locking units  142  of the position adjusting bushings  140  are inserted and locked.  
      The locking unit installation openings  132  allow the respective locking units  142  to be inserted into the inside of the respective position adjusting indentations  131 , so that the locking unit installation openings  132  can be installed on and locked into the given positions of the rotor  130 . As a result, reliability in the rotation of the rotor  130  can be improved. Also, since the locking units  142  need to be locked into the outside of the respective position adjusting indentations  131 , each of the locking units  142  has a larger diameter and width than each of the position adjusting indentations  131 , and is shallower than each of the position adjusting indentations  131 .  
      The above described motor with the position-adjustable rotor operates as follows.  
      Referring to  FIGS. 2A and 2B , the position adjusting bushings  140  are inserted into the rotational shaft  120 , but the insertion units  141  are made to be inserted into the respective position adjusting indentations  131  of the rotor  130  so as to minimize gaps between the rotor  130  and each of the holder assemblies, i.e., the bearing covers  114 .  
      Referring to  FIG. 3 , when the position of the rotor  130  is changed such that the gaps between the rotor  130  and each of the bearing covers  114  are maximized by changing the specification or structure of the motor  100 , the direction that the position adjusting bushings  140  are inserted into the rotational shaft  120  is reversed, so that the locking units  142  are supported individually at the exterior side of each of the position adjusting indentations  131 .  
      Therefore, as illustrated in  FIG. 4 , there arises a distance difference “d” between edge portions of the position adjusting bushings  140  that protrude and adjust gaps between the rotor  130  and each of the holder assemblies  110  by changing the direction that the position adjusting bushings  140  are inserted into the rotational shaft  120 . As a result, the position of the rotor  130 , more particularly, gaps between the rotor  130  and each of the holder assemblies  110  can be adjusted.  
      It is exemplified in the present embodiment that the position adjusting bushings  140  adjust gaps between the rotor  130  and each of the bearing covers  114  of the holder assemblies  110 . However, in consideration of the holder assemblies  110  that can be formed in various structures, a gap between the rotor  130  and any member of the holder assemblies  110  facing the rotor  130  can be adjusted.  
      Meanwhile, when the locking units  142  of the position adjusting bushings  140  are supported by the rotor  130 , the locking units  142  are installed on and locked into the respective locking unit installation openings  132  formed at the entrance side of the respective position adjusting indentations  131  so as to guide the firm fixation of the corresponding position adjusting bushings  140  to a target.  
      According to the motor  100  with the position-adjustable rotor  130  as described above, different from the conventional rotor  130  formed by stacking the identically shaped silicon steel sheets over each other, since the rotor  130  is formed by molding through pressing the soft magnetic powder, the position adjusting indentations  131  and the locking unit installation openings  132  can be formed. Also, gaps between the rotor  130  and each of the holder assemblies  110  can be adjusted by changing the direction that the position adjusting bushings  140  are inserted into the rotational shaft  120 , and the gap adjustment can be performed easily. Hence, substantially the same rotor can be implemented to those motors having different specifications or structures, and this wide implementation allows reduction in manufacturing costs.  
      On the basis of various embodiments of the present invention, the motor with the position-adjustable rotor can adjust gaps between the rotor and each of the holder assemblies. The gap adjustment can be done easily, and thus, even though motors have different specifications or structures, substantially the same motor can be implemented thereto. As a result, the motors can be manufactured at low cost.  
      While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.