Patent Publication Number: US-2023155443-A1

Title: Permanent magnet electric motor

Description:
TECHNICAL FIELD 
     The present invention relates to an inner-rotor permanent magnet electric motor including a rotor disposed coaxially with a cylindrical stator on the inner diameter side of the stator. 
     BACKGROUND ART 
     As an electric motor, an inner-rotor permanent magnet electric motor has been conventionally known, in which a columnar rotor including a permanent magnet portion is disposed coaxially with a cylindrical stator, which generates a rotating magnetic field, on the inner diameter side of the cylindrical stator. 
     This type of permanent magnet electric motor includes a permanent magnet electric motor including: a rotor including an annular permanent magnet portion facing a stator in a radial direction; and a coupling portion (yoke) that couples the permanent magnet portion to a shaft. In the permanent magnet electric motor of Patent Literature 1, a bearing house portion (bearing bracket) that holds a bearing is disposed close to the rotor in the axis direction of the stator, so that the electric motor is downsized in the axis direction. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-open No. 2011-109861 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     However, there has been a problem that, if the bearing house portion (bearing bracket) formed of a magnetic substance is disposed close to the permanent magnet portion of the rotor, the magnetic flux flowing from the permanent magnet portion of the rotor to the yoke (coupling portion) side of the stator also flows to the bearing house portion side, and a leakage flux increases, so that the output of the permanent magnet electric motor is lowered. 
     Advantageous Effects of Invention 
     In this regard, it is an object of the present invention to provide a permanent magnet electric motor that can be downsized in an axis direction and can suppress a leakage flux. 
     Solution to Problem 
     According to an aspect of the present invention, there is provided a permanent magnet electric motor including: a columnar rotor including a permanent magnet portion annularly disposed; a shaft disposed along a rotation axis of the rotor; a cylindrical stator core disposed on an outer circumferential side of the rotor; a main body including a shell integrally formed with the stator core; a bracket attached to one end side of the main body; and a bearing that rotatably supports the shaft. 
     The bracket includes a bearing house portion that stores the bearing, and a non-magnetic portion that is connected to the bearing house portion. 
     The bearing house portion is disposed on an inner diameter side relative to the permanent magnet portion as viewed from an axis direction of the rotation axis. 
     An edge portion of the bearing house portion on an outer diameter side is covered with the non-magnetic portion. 
     According to the present invention, it is possible to downsize an electric motor in an axis direction of a rotation axis and to suppress a leakage flux flowing from a permanent magnet portion of a rotor to a bearing house portion side. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an overall perspective view of a permanent magnet electric motor according to the present invention. 
         FIG.  2    is a transverse cross-sectional view of the permanent magnet electric motor according to the present invention. 
         FIG.  3    is a perspective view of a bracket of the permanent magnet electric motor according to the present invention. 
         FIG.  4    is an overall perspective view of the permanent magnet electric motor according to the present invention, showing a state in which the bracket of  FIG.  3    is removed. 
         FIG.  5    is a cross-sectional view of a cross-section taken along a slitted groove shown in  FIG.  1   . 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     Next, an embodiment of the present invention will be described with reference to the drawings. In the following description about the drawings, the same or similar portions will be denoted by the same or similar reference symbols. It should be noted that the drawings are schematic and may differ from reality. Therefore, specific constituent parts should be determined by referring to the following description. 
     Further, the embodiment to be described below exemplifies apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the shape, structure, arrangement, and the like of the constituent parts to those described below. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims. 
     Hereinafter, an electric motor according to an embodiment of the present invention will be described. 
     &lt;Overall Configuration of Electric Motor&gt; 
       FIGS.  1  to  5    are views for describing a configuration of a permanent magnet electric motor  1  of this embodiment. As shown in those figures, the permanent magnet electric motor  1  is a brushless DC motor, for example. The permanent magnet electric motor  1  is, for example, used to rotationally drive a blower fan mounted in an outdoor unit of an air conditioner, though not shown in the figures. 
     As shown in  FIGS.  1  and  2   , the permanent magnet electric motor  1  of this embodiment includes a stator  2 , a rotor  3 , a motor shell (casing, main body)  10 , and a bracket  41 . 
     Hereinafter, an inner-rotor permanent magnet electric motor  1  will be described as an example, in which a columnar rotor  3  including a permanent magnet portion  31  is rotatably disposed inward in the radial direction of a cylindrical stator  2  that generates a rotating magnetic field. 
     &lt;Rotor, Stator, and Motor Shell&gt; 
     As shown in  FIG.  2   , the rotor  3  includes an annular permanent magnet portion  31  and a coupling portion  35 , which is disposed on the inner diameter side relative to the permanent magnet portion  31  and couples the permanent magnet portion  31  and a shaft  32  to each other. The shaft  32  is fixed to the columnar rotor  3  along the center axis of the rotor  3 . In this embodiment, the permanent magnet portion  31  and the coupling portion  35  of the rotor  3  are formed by integral molding of a resin material in which a ferrite magnetic substance is mixed. After the molding, only the permanent magnet portion  31  is magnetized to cause the permanent magnet portion  31  to function as a ferrite bonded magnet. Further, the permanent magnet portion  31  is magnetized to be a polar anisotropic magnet in which a south pole and a north pole alternately appear in the circumferential direction thereof. Thus, a part of a yoke for concentrating the flow of the magnetic flux of the permanent magnet portion  31  becomes unnecessary, and the leakage flux can be suppressed. 
     Note that the permanent magnet portion  31  and the coupling portion  35  may be formed separately. For example, the rotor  3  may be a so-called surface magnet (SPM) rotor, in which a plurality of ferrite sintered magnets (corresponding to the permanent magnet portion  31 ), which are obtained by sintering a powder-like ferrite magnetic substance in a mold, are annularly attached to the outer circumferential surface of a rotor core (corresponding to the coupling portion  35 ). 
     The stator  2  includes a stator core  21  including a cylindrical yoke portion (not shown) and a plurality of teeth portions (not shown) extending from the yoke portion to the inner diameter side, and winding (not shown) wound around the teeth portion via an insulator. The stator  2  is covered with the motor shell  10  (main body) formed of resin by resin integral molding, except for the inner circumferential surface of the stator core  21  (see  FIGS.  2  and  4   ). Specifically, the motor shell  10  covers the stator  2  including the stator core  21  and the winding. As shown in  FIGS.  1  and  2   , the stator  2  is disposed on the outer circumferential side of the rotor  3  (outward in the radial direction of the permanent magnet electric motor  1 ). Further, the stator core  21  of the stator  2  is disposed such that the teeth portion of the stator core  21  faces the permanent magnet portion  31  of the rotor  3  in the radial direction. In other words, the stator  2  is disposed such that the annular permanent magnet portion  31  of the rotor  3  faces the stator core  21  of the stator  2  in the radial direction. 
     The motor shell  10  may have any shape. For example, the motor shell  10  may be formed into a hollow cylindrical shape having an open end surface on one side (in the embodiment, the opposite output side of the shaft  32 ) in the axis direction of the center axis of the permanent magnet electric motor  1 , that is, the rotation axis of the rotor  3  (hereinafter, rotation axis C). In this embodiment, the motor shell  10  includes an annular portion  12  and an end surface portion  13  formed at the end portion of the annular portion  12  on the opposite side of the opening. 
     The rotor  3  is rotatably disposed on the inner circumferential side of the stator core  21  of the stator  2  with a predetermined clearance (gap) from the stator core  21 . As shown in  FIGS.  2 ,  4 , and  5   , the permanent magnet portion  31  formed in an annular shape is disposed on the outer side (outer circumference side) in the radial direction of the rotor  3  so as to face the stator core  21 . 
     The rotor  3  is fixed to the circumference of the shaft  32 . The shaft  32  is rotatably supported (held) by a first bearing  33  and a second bearing  34  fixed to the outer circumferential surface of the shaft  32 . Further, the first bearing  33  is stored (held) in a first bearing storing portion  42  (bearing house portion) to be described later, and the second bearing  34  is stored (held) in a second bearing storing portion  43  to be described later, so that the rotor  3  is rotatably supported. The first bearing storing portion  42  and the second bearing storing portion  43  are formed of, for example, a magnetic substance of chromium-nickel-based stainless steel. 
     &lt;Bearing, Bracket, and Bearing House Portion&gt; 
     As shown in  FIGS.  2 ,  3 , and  5   , the first bearing  33  is fixed to one end side (opposite output side) of the shaft  32  at the inner race side of the first bearing  33 . The second bearing  34  is fixed to the other end side (output side) of the shaft  32  at the inner race side of the second bearing  34 . The first bearing  33  and the second bearing  34  (a pair of bearings) cooperate to rotatably support the shaft  32  and the rotor  3  fixed to the shaft  32 . For example, a ball bearing is used for each of the first bearing  33  and the second bearing  34 . 
     The bracket  41  includes the first bearing storing portion  42  that is formed of a magnetic substance and stores the first bearing  32 , and a non-magnetic portion  44  (end surface portion) formed of a non-magnetic substance (e.g., resin). In the motor shell  10  (main body) of the permanent magnet electric motor  1 , the bracket  41  is disposed at an end in the center axis C direction, that is, disposed on the opposite output side of the shaft  32 . The non-magnetic portion  44  of the bracket  41  includes a connection portion  45  connected to the first bearing storing portion  42  (see  FIGS.  2 ,  3 , and  5   ). The non-magnetic portion  44  of the bracket  41  is integrally formed with the first bearing storing portion  42 , which is a magnetic portion, by insert molding. The non-magnetic portion  44  is connected to the first bearing storing portion  42  (bearing house portion) at the connection portion  45 . The bracket  41  is attached to the end portion of the motor shell  10  (main body) on the opposite output side by using screws to serve as a lid for covering the opening of the motor shell  10  (main body). Note that the opening of the motor shell  10  may be provided toward the output side. In this case, the bracket  41  is disposed not on the opposite output side of the shaft  32  but on the output side of the shaft  32 . 
     The non-magnetic portion  44  (end surface portion) of the bracket  41  is formed into a substantially circular plate shape having the outer shape in the radial direction, which expands to the outer circumferential surface of the motor shell  10  in the radial direction. The non-magnetic portion  44  of the bracket  41  forms a resin shell of the permanent magnet electric motor  1  together with the motor shell  10 . Additionally, the non-magnetic portion  44  includes protrusions  410 , which protrude outward in the radial direction relative to the outer circumferential surface of the motor shell  10 , as viewed from the rotation axis C direction. The protrusions  410  each abut on the basal end portion of a guard portion  102  of the motor shell  10 . The guard portion  102  will be described later. 
     The protrusions  410  of the bracket  41  are formed as many as the guard portions  102  provided to the motor shell  10  (three positions). For example, the protrusions  410  are each formed into a trapezoid as viewed from the rotation axis C direction and each include, at the center portion thereof, a screw through hole  413  penetrating in the rotation axis C direction. 
     Note that the bracket  41  includes a slitted groove  416  for providing an electrically conductive member  5  for measures against electrolytic corrosion, which will be described later, in the outer surface exposed to the outside in the permanent magnet electric motor  1  after assembling (see  FIGS.  1  and  3   ). 
     The slitted groove  416  extends outward in the radial direction from the center portion of the bracket  41  (tubular connection portion  45  of the non-magnetic portion  44  to be described later) to the outer circumferential surface of the bracket  41 , and further extends in the axis direction from there to the position abutting on the motor shell  10 . 
     The bracket  41  is fitted into the motor shell  10  (main body) and then screwed at screw holes  103  (to be described later) of the guard portions  102  of the motor shell  10  via the screw through holes  413  (see  FIG.  1   ). 
     Further, the first bearing storing portion (bearing house portion)  42  for storing the first bearing  33  on the inner side (output side) of the permanent magnet electric motor  1  is disposed at the center portion of the circular plate shape bracket  41 . The first bearing storing portion  42  is formed into, for example, a substantially bottomed cylindrical shape by press working. 
     The second bearing storing portion (bearing house portion)  43  for storing the second bearing  34  on the inner side (opposite output side) of the permanent magnet electric motor  1  is disposed at the center portion of the output side end portion of the motor shell  10 . The second bearing storing portion  43  is formed into, for example, a substantially bottomed cylindrical shape similarly to the first bearing storing portion  42 . The second bearing storing portion  43  is disposed inward (inner diameter side) relative to the annular permanent magnet portion  31  in the radial direction of the rotor  3 . The end surface portion  13  of the motor shell  10  includes a connection portion  14  that is connected to a flange portion  432  (to be described later) of the second bearing storing portion  43 . 
     As shown in  FIGS.  2  and  5   , the first bearing storing portion (bearing house portion)  42  includes a tubular portion  421  that holds the outer race side of the first bearing  33  from the radial direction, an annular flange portion  422  that extends outward in the radial direction of the rotor  3  from one end portion of the tubular portion  421  in the rotation axis C direction, and a coronal portion  423  that extends inward in the radial direction from the other end portion of the tubular portion  421  in the rotation axis C direction. The coronal portion  423  covers the other end side of the first bearing  33  in the rotation axis C direction. The outer circumferential edge of the annular flange portion  422  is located inward (inner circumferential side) in the radial direction of the rotor  3  relative to the permanent magnet portion  31 . In other words, the first bearing storing portion  42  is formed so as not to overlap with the permanent magnet portion  31  as viewed from the rotation axis C direction of the rotor  3 . 
     Specifically, the first bearing storing portion  42  (bearing house portion of the bracket  41 ) is disposed inward (inner diameter side) in the radial direction of the rotor  3  relative to the permanent magnet portion  31 , as viewed from the rotation axis C direction. Further, the outer circumferential edge portion (edge portion on the outer diameter side) of the flange portion  422  of the first bearing storing portion  42  (bearing house portion) is covered with resin that is a non-magnetic substance. Specifically, in the bracket  41 , the outer circumferential edge portion of the flange portion  422  of the first bearing storing portion  42  is covered with the non-magnetic portion  44  made of resin. 
     As described above, the bracket  41  is formed by the first bearing storing portion (magnetic portion)  42 , which is one of the pair of bearing storing portions (bearing house portions), and the non-magnetic portion  44  (end surface portion). The first bearing storing portion (magnetic portion)  42  is disposed on the inner diameter side relative to the permanent magnet portion  31  in the radial direction of the rotor  3 , and thus can prevent the flange portion  422  of the first bearing storing portion  42  serving as a magnetic portion from facing the permanent magnet portion  31  in the rotation axis C direction. This makes it possible to suppress a leakage flux flowing from the permanent magnet portion  31  to the first bearing storing portion (magnetic portion)  42 . Furthermore, in the first bearing storing portion (magnetic portion)  42 , the outer circumferential edge portion of the flange portion  422 , which is disposed close to the permanent magnet portion  31  of the rotor  3 , is covered with the non-magnetic portion  44 . This makes it possible to block the path of the leakage flux flowing from the permanent magnet portion  31  to the first bearing storing portion (bearing house portion)  42  formed of a magnetic substance by the non-magnetic portion  44  formed of a non-magnetic substance, and thus further possible to suppress the leakage flux flowing from the permanent magnet portion  31  to the first bearing storing portion  42 . 
     Note that such a structure for suppressing the leakage flux can be applied to not only the first bearing storing portion  42  side but also the second bearing storing portion  43  side. At that time, the second bearing storing portion  43  is formed into the shape similar to that of the first bearing storing portion  42  and includes a tubular portion  431  that holds the outer race side of the second bearing  34  from the radial direction, an annular flange portion  432  that extends outward in the radial direction of the rotor  3  from one end portion of the tubular portion  431  in the rotation axis C direction, and a coronal portion  433  that extends inward in the radial direction from the other end portion of the tubular portion  431  in the rotation axis C direction. Additionally, the second bearing storing portion  43  is disposed on the inner diameter side relative to the permanent magnet portion  31  in the radial direction of the rotor  3 . Further, the outer circumferential edge portion of the flange portion  422  of the second bearing storing portion  43  is covered with the end surface portion  13  (connection portion  14 ) of the resin motor shell  10  that is a non-magnetic substance. This makes it possible to suppress the leakage flux flowing from the permanent magnet portion  31  to the second bearing storing portion  43 . 
     The non-magnetic portion (end surface portion)  44  of the bracket  41  includes the connection portion  45  connected to the first bearing storing portion (bearing house portion)  42 . The connection portion  45  is formed into a substantially tubular shape, and the flange portion  422  of the first bearing storing portion (bearing house portion)  42  is inserted into and fixed to the side surface of the tubular connection portion  45  on the inner diameter side. Here, the tubular portion  421  of the first bearing storing portion  42  is not in contact with the non-magnetic portion  44  of the bracket  41  (is not covered with the non-magnetic portion  44 ), and only the outer circumferential edge portion of the flange portion  422  is joined (connected) to the connection portion  45  of the non-magnetic portion  44  so as to be covered therewith. Further, a clearance portion (air gap) AG 1  is formed between the tubular portion  421  of the first bearing storing portion  42  and the tubular connection portion  45  of the non-magnetic portion  44 . With this configuration, the deformation of the motor shell  10  due to heat, shock, or the like hardly affects the first bearing  33 . Furthermore, the contact area between the connection portion  45  of the bracket  41  and the flange portion  422  of the first bearing storing portion  42  can be reduced, and thus the heat generated at the winding wound in the stator core  21  can be prevented from being transmitted to the first bearing  33  via the bracket  41 . This makes it possible to suppress an increase in temperature of the first bearing  33  and prevent the first bearing  33  from deteriorating. 
     In this embodiment, the second bearing storing portion  43 , which is the other one of the pair of bearing storing portions, also has the structure similar to that of the first bearing storing portion  42 . Specifically, the motor shell  10  is formed into a bottomed cylindrical shape and includes the annular portion  12  of the motor shell  10 , which is integrally formed with the stator  2 , and the end surface portion  13  of the motor shell  10 , which is connected to the end portion of the annular portion  12  and expands inward (inner circumferential side) in the radial direction. Additionally, the end surface portion  13  of the motor shell  10  includes the cylindrical connection portion  14  connected to the second bearing storing portion  43 . Further, similarly to the first bearing storing portion  42 , the second bearing storing portion  43 , which is the other one of the pair of bearing storing portions, includes the tubular portion  431  and the flange portion  432  extending outward in the radial direction from the tubular portion  431 , and only the outer circumferential edge portion of the flange portion  432  is inserted into and fixed to the side surface of the connection portion  14  of the resin shell (motor shell  10 ) on the inner diameter side. Further, a clearance portion (air gap) AG 2  is formed between the tubular portion  431  of the second bearing storing portion  43  and the connection portion  14  of the resin shell (motor shell  10 ). 
     With this configuration, the deformation of the motor shell  10  due to heat, shock, or the like hardly affects the second bearing  34 . Furthermore, the contact area between the connection portion  14  of the motor shell  10  and the flange portion  432  of the second bearing storing portion  43  can be reduced, and thus the heat generated at the winding wound in the stator core  21  can be prevented from being transmitted to the second bearing  34  via the resin shell  10 . This makes it possible to suppress an increase in temperature of the second bearing  34  and prevent the second bearing  34  from deteriorating. 
     Further, as described above, the rotor  3  includes the coupling portion  35 , to which the shaft  32  is fixed and which couples the permanent magnet portion  31  and the shaft  32  to each other. The permanent magnet portion  31  is disposed so as to face the cylindrical stator core  21  in the radial direction. The coupling portion  35  is disposed on the inner diameter side of the permanent magnet portion  31  annularly disposed. As shown in  FIGS.  2  and  4   , the coupling portion  35  includes a recess  36  that is recessed toward the center of the coupling portion  35  in the axis direction of the rotation axis C (rotation axis C direction). The recess  36  is formed such that the thickness of the coupling portion  35  in the rotation axis C direction at the position at which the recess  36  is formed is smaller than the thickness of the permanent magnet portion  31  in the rotation axis C direction. Additionally, the flange portion  422  of the first bearing storing portion  42  is disposed so as to overlap with the recess  36  in the rotation axis C direction. This makes it possible to form the annular recess  36  recessed toward the rotation axis C direction in the rotor  3 , so that the flange portion  422  of the first bearing storing portion  42  can be disposed within the recess  36 . 
     In such a manner, a part of the first bearing storing portion  42  (flange portion  422 ) enters the annular recess  36  recessed in the axis direction of the rotation axis C, thus reducing the thickness of the permanent magnet electric motor  1  in the rotation axis C direction and downsizing the permanent magnet electric motor  1  in the rotation axis C direction. 
     As shown in  FIG.  4   , terminal pins  26  electrically connected to the winding (not shown) of the stator core  21 , and bosses  27  each serving as a guide used when a substrate (not shown) is attached are provided at the end portion (upper end portion in  FIG.  4   ) of the stator  2  on the opposite output side in the rotation axis C direction. 
     The bracket  41  functions as an insulation cover for preventing the terminal pins  26  from being exposed to the outside of the permanent magnet electric motor  1 . In this embodiment, the terminal pins  26  are provided at three positions, and the bracket  41  is attached to the motor shell  10  so as to cover up those three positions. 
     The bracket  41  includes a cover main body  414  to be attached along the upper end surface of the stator  2  and a fitting portion  415  integrally formed with the cover main body  414 . The cover main body  414  and the fitting portion  415  correspond to the non-magnetic portion  44  (end surface portion). 
     The cover main body  414  is formed into a circular plate shape as a whole. As shown in  FIG.  3   , the fitting portion  415  is formed as an annular projection disposed at the outer circumferential edge portion of the cover main body  414 . The fitting portion  415  is fitted into the end portion of the motor shell  10  on the opposite output side (upper end surface of the motor shell  10  in  FIG.  4   ) from the rotation axis C direction, so that the motor shell  10  (main body) and the bracket  41  are aligned with each other, and the first bearing  33  is stored in the first bearing storing portion  42  of the bracket  41  as shown in  FIG.  2   . 
     The motor shell  10  includes the three guard portions  102  arranged at regular intervals in the circumferential direction at the end portion of the rotation axis C on the opposite output side. Note that any number of guard portions  102 , such as two or six guard portions  102 , may be provided, and the plurality of guard portions  102  need not be arranged at regular intervals. Those three guard portions  102  each protrude into a trapezoidal shape in the radial direction of the stator  2  (permanent magnet electric motor  1 ) and each have a predetermined thickness in the rotation axis C direction. 
     As shown in  FIGS.  1  and  4   , each guard portion  102  includes a cutout portion  104  for fitting a vibrationproof rubber bush  6  thereinto, the cutout portion  104  being formed from the outside in the radial direction of the stator  2  (permanent magnet electric motor  1 ) to the inner radial direction. This cutout portion  104  is formed so as to connect a hole formed in each guard portion  102  to penetrate in the rotation axis C direction and the outer circumferential edge of the guard portion  102  to each other. Furthermore, each guard portion  102  includes the screw hole  103 , through which the above-mentioned bracket  41  is screwed. 
     The lower surface (surface on the output side) of each guard portion  102  includes a circular recess portion  106  formed to easily hold the vibrationproof rubber bush  6  (see  FIGS.  1  and  4   ). 
     As shown in  FIG.  5   , any one of the three guard portions  102  includes a slitted groove  105  for arranging the electrically conductive member  5  for measures against electrolytic corrosion (see  FIG.  5   ) along the rotation axis C direction, the slitted groove  105  being formed from the position on the most inner diameter side of the cutout portion  104  in the radial direction of the stator  2  (permanent magnet electric motor  1 ) toward the center axis  32 . Along this slitted groove  105 , a slitted groove for the electrically conductive member  5  is also formed on the side surface and the end surface portion  13  (surface on the output side) of the motor shell  10  so as to extend in the axis direction of the center axis  32  and the radial direction (not shown). 
     The electrically conductive member  5  is a strip-shaped member for electrical conduction between the first bearing  33  and the second bearing  34 . The electrically conductive member  5  is formed by, for example, punching a steel plate into a strip shape and bending the obtained steel plate into a squared U shape along the outer surfaces of the motor shell  10  and the bracket  41  (see  FIG.  5   ). The electrically conductive member  5  allows the potentials of the first bearing  33  and the second bearing  34  on the outer race side to be the same, and thus the generation of electrolytic corrosion can be suppressed. 
     Here, when the bracket  41  is fitted into the motor shell  10 , the slitted groove  416  of the bracket  41  and the slitted groove  105  formed in the outer surface of the motor shell  10  become continuous, and both the slitted grooves become a guide into which the strip-shaped electrically conductive member  5  is to be embedded. This makes it possible to prevent the strip-shaped electrically conductive member  5  from protruding from the surface of the shell of the permanent magnet electric motor  1  and from dropping. As shown in  FIG.  5   , the electrically conductive member  5  is disposed to extend from the position of the flange portion  422  of the first bearing storing portion  42  to the position of the flange portion  432  of the second bearing storing portion  43  through the slitted groove  416  of the bracket  41 , the slitted groove  105  of the guard portion  102 , and the slitted groove of the outer circumferential surface of the motor shell  10 . 
     Further, before the vibrationproof rubber bush  6  is fitted into the guard portion  102 , the electrically conductive member  5  is inserted into the slitted groove  105  in advance, so that the vibrationproof rubber bush  6  can press the electrically conductive member  5  from the outside, and the electrically conductive member  5  can be prevented from dropping. 
     As described above, in this embodiment, the bearing house portions (first bearing storing portion  42 , second bearing storing portion  43 ) each formed of a magnetic substance are disposed so as not to face the annular permanent magnet portion  31  in the rotation axis C direction. Additionally, the outer circumferential edge portion of the flange portion  422  of the bearing house portion  42  is covered with the non-magnetic portion  44  formed of a non-magnetic substance so as not to generate the path of the magnetic flux, which short-circuits between the bearing house portions  42  and  43  and the rotor  3  (permanent magnet portion  31 ) in the radial direction of the stator  2  (permanent magnet electric motor  1 ). 
     This makes it possible to suppress the generation of a leakage flux by blocking the path of the leakage flux flowing from the permanent magnet portion  31  to the bearing house portions  42  and  43  even if the bearing house portion  42  is disposed close to the permanent magnet portion  31  in the axis direction of the rotation axis C (rotation axis C direction). Further, since the bearing house portion  42  can be disposed close to the permanent magnet portion  31  in the axis direction of the rotation axis C (rotation axis C direction), so that the permanent magnet electric motor  1  can be downsized in the axis direction of the rotation axis C. 
     REFERENCE SIGNS LIST 
     
         
           1  permanent magnet electric motor 
           10  motor shell (main body) 
           12  annular portion 
           13  end surface portion 
           2  stator 
           21  stator core 
           3  rotor 
           31  permanent magnet portion (magnetized portion) 
           32  shaft 
           33  first bearing 
           34  second bearing 
           35  coupling portion 
           36  recess 
           41  bracket 
           42  first bearing storing portion (bearing house portion) 
           421  tubular portion 
           422  flange portion 
           423  coronal portion 
           43  second bearing storing portion (bearing house portion) 
           44  non-magnetic portion (end surface portion) 
           45  connection portion 
         AG 1 , AG 2  clearance portion (air gap) 
         C rotation axis