Abstract:
An object is to provide a mover that holds magnets and that achieves weight reduction and has reliability of strength. The present invention relates to the mover of a linear motor. The mover includes a plurality of the magnets, the magnets being arrayed along a first direction, and metal covers, the metal covers being provided on both sides of the magnets so as the magnets are interposed therebetween and thus held in place. A plurality of protrusions, the protrusions extending in a second direction that is perpendicular to the first direction and formed in the metal covers on a surface at a side of the magnets. The magnets are provided between the protrusions.

Description:
FIELD 
       [0001]    The present invention relates to a mover and a linear motor equipped with the mover. 
       BACKGROUND 
       [0002]    A motor called a moving-magnet linear motor, in which a plurality of magnets are held in a mover without a back yoke being provided to the mover, is in conventional use. For example, Patent Literature 1 discloses a mover that holds magnets that are fitted in holes formed in an aluminum block. 
       CITATION LIST 
     Patent Literature 
       [0003]    Patent Literature 1: Japanese Patent Application Laid-open No. 2007-312501 
       SUMMARY 
     Technical Problem 
       [0004]    However, according to the conventional technique described above, the weight of the mover tends to increase because of the use of the aluminum block. If the weight of the mover increases, there is a problem in that it is difficult to sufficiently take advantage of the mover&#39;s acceleration performance. Furthermore, in order to prevent deformation of the mover due to the attractive magnetic forces of the magnets, the mover is required to be of sufficient strength. 
         [0005]    The present invention has been achieved in view of the above problems and an objective of the present invention is to provide a mover that holds magnets and that is designed to ensure weight reduction and to ensure it has a certain strength. 
       Solution to Problem 
       [0006]    In order to solve the problems mentioned above and achieve the objective, the present invention relates to a mover of a linear motor. The mover includes: a plurality of magnets, the magnets being provided along a first direction; and metal covers, provided on both sides of the magnets, between which the magnets are interposed and by which the magnets are held. A plurality of protrusions are provided, and the protrusions extend in a second direction that is perpendicular to the first direction and formed in the metal covers and on a surface regarded as a side of the magnets, and the magnets are provided between the protrusions. 
       Advantageous Effects of Invention 
       [0007]    The mover according to the present invention can hold magnets in place whilst achieving the effect of ensuring weight reduction and strength. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]      FIG. 1  is a perspective view illustrating a schematic configuration of a linear motor according to a first embodiment of the present invention. 
           [0009]      FIG. 2  is an exploded perspective view of the linear motor. 
           [0010]      FIG. 3  is an exploded perspective view of a mover. 
           [0011]      FIG. 4  is a perspective view of metal covers. 
           [0012]      FIG. 5  is a plan view of the metal covers. 
           [0013]      FIG. 6  is a sectional view taken along a line A-A illustrated in  FIG. 5 . 
           [0014]      FIG. 7  is an exploded perspective view of a mover according to a first modification. 
           [0015]      FIG. 8  is an exploded perspective view of a mover according to a second modification. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0016]    Exemplary embodiments of a mover and a linear motor equipped with the mover according to the present invention will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments. 
       First embodiment 
       [0017]      FIG. 1  is a perspective view illustrating a schematic configuration of a linear motor according to a first embodiment of the present invention.  FIG. 2  is an exploded perspective view of the linear motor. A linear motor  50  includes stationary parts  10  and a mover  30 . In the linear motor  50 , the mover  30  provided between the stationary parts  10  is movable along a direction (first direction) indicated by an arrow X. 
         [0018]    Each of the stationary parts  10  is configured by attaching a magnetic-field generating unit  12  and guide rails  13  to a stationary base  11 . A pair of stationary bases  11  is provided between which the mover  30  interposes; and the magnetic-field generating unit  12  is attached to each of the stationary bases  11 . Magnetic-field generating units  12  are provided such that they extend in the direction indicated by the arrow X. The magnetic-field generating units  12  are provided such that they face each other. The magnetic-field generating units  12  are, for example, armatures or back yokes, and they generate a magnetic field for moving the mover  30 . Combinations are possible, for example, in which one of the magnetic-field generating units  12  is an armature and the other magnetic-field generating unit  12  is a back yoke or in which both of the magnetic-field generating units  12  are armatures. The guide rails  13  are provided on both sides of each of the magnetic-field generating units  12  and extend in the direction indicated by the arrow X. 
         [0019]      FIG. 3  is an exploded perspective view of the mover  30 . The mover  30  includes metal covers  31 , magnets  32 , and reinforcing parts  33 . The metal covers  31  are formed by folding thin metallic plates such as thin stainless-steel plates. In the mover  30 , two metal covers  31  are provided and the magnets  32  and the reinforcing parts  33  are interposed and held therebetween. 
         [0020]      FIG. 4  is a perspective view of the metal covers  31 .  FIG. 5  is a plan view of the metal covers  31 .  FIG. 6  is a sectional view taken along a line A-A illustrated in  FIG. 5 . In each of the metal covers  31 , one or more protrusions  34  are formed. The protrusions  34  extend in a direction (second direction) indicated by an arrow Y perpendicular to the direction indicated by the arrow X and are formed by means of folding the metallic thin plate. 
         [0021]    A plurality of magnets  32  are fitted between the protrusions  34  that are adjacent to each other, respectively, so that the magnets  32  are arrayed along the direction indicated by the arrow X. The width between the protrusions  34  that are adjacent to each other and the width of each of the magnets  32  in the direction indicated by the arrow X are substantially equal and the magnets  32  are fitted between the protrusions  34  that are adjacent to each other, respectively, thereby preventing the displacements of the magnets  32  in the direction indicated by the arrow X. 
         [0022]    The reinforcing parts  33  are formed of, for example, a resin material and are provided on both sides of each of the magnets  32 . Through hole  33   a  and through hole  31   a  are formed in the reinforcing part  33  and the metal covers  31 , respectively. The reinforcing parts  33  are provided at positions where the through holes  33   a  and the through holes  31   a  overlap with each other. By using the through holes  33   a  and  31   a,  mounting seats can be provided on the mover  30  for mounting the linear guides  35  onto the mover  30 , or the linear guides  35  can be directly attached to the mover  30 . 
         [0023]    The linear guides  35  attached with the use of the through holes  33   a  and  31   a  and the guide rails  13  provided on the stationary parts  10  engage with each other so that the mover  30  is guided along the guide rails  13  so as to be movable in the direction indicated by the arrow X. 
         [0024]    The reinforcing parts  33  are formed to have substantially the same height as that of the magnets  32  and function as reinforcing members that prevent the metal covers  31  from being crushed at portions where the magnets  32  are not present. In the present embodiment, the reinforcing parts  33  are provided between the adjacent protrusions  34  of the metal covers  31  and at both ends thereof in the direction indicated by the arrow Y. Gaps are provided between the magnets  32  and the reinforcing parts  33 . In a case where the reinforcing parts  33  are provided near the through holes  31   a  so that a certain space is formed between the magnets  32  and the reinforcing parts  33 , as illustrated in  FIG. 4 , the weight can be further reduced as compared to a mover configured by fitting magnets in an aluminum block even when a material having a larger specific gravity than that of aluminum is used as the reinforcing parts  33 . Instead of using the reinforcing parts  33  made of resin, nuts or washers made of, for example, metal (such as iron) can be used. The magnets  32  and the reinforcing parts  33  are fixed to the metal covers  31 , thereby suppressing displacement in the direction indicated by the arrow Y. The magnets  32  and the reinforcing parts  33  are adhered to the metal covers  31 , for example, with an adhesive. 
         [0025]    In accordance with the mover  30  described above, the magnets  32  are interposed between and held by the metal covers  31 , which are formed from a thin plate. Therefore, the weight of the mover  30  can be reduced when compared to a case where the magnets  32  are fitted and held in a metallic block. 
         [0026]    Reduction in the weight of the mover  30  enables easier enhancement of the acceleration rate of the mover  30 . Because gaps are formed between the magnets  32  and the reinforcing parts  33 , the weight can be reduced by as much as the gaps. Furthermore, by forming the reinforcing parts  33  of a resin material, further reduction in the weight can be brought. 
         [0027]    Because the width of the magnets  32  in the direction indicated by the arrow X and the width between the protrusions  34  that are adjacent are substantially equal and the magnets  32  are fitted into between the protrusions  34  that are adjacent, displacement of the magnets  32 , due to acceleration or deceleration during movement of the mover  30 , can be reduced in the direction indicated by the arrow X. 
         [0028]    Because the metal covers  31  are formed by folding a metallic thin plate, the working thereof is easy and the manufacturing cost can be reduced. Furthermore, when compared to the case where the magnets  32  are held using a metallic block, the amount of material used can be reduced and the manufacturing cost can be further reduced. 
         [0029]    When the linear guides  35  are attached directly to the mover  30  by using the through holes  31   a  and  33   a , mounting seats for mounting the linear guides  35  thereon are not required and thus the structure of the mover  30  can simplified and its weight can be reduced. 
         [0030]    Folding to form the protrusions  34  can increase the strength of the metal covers  31 . Accordingly, even when the metal covers  31  are formed from a thin plate, sufficient strength can be easily ensured. In the linear motor  50 , a force to deform the mover  30  may be applied thereto because the magnets  32  are pulled due to magnetic forces. Therefore, by increasing the strength of the metal covers  31 , deformation of the mover  30  can be ensured. 
         [0031]    It becomes difficult for the mover  30  to deform such that it becomes uneven when viewed from the direction indicated by the arrow Y because the mover  30  is held and restricted by the guide rails  13  that extend in the direction indicated by the arrow X and that hold the mover  30 . Furthermore, deformation of the mover such that it becomes uneven when viewed from the direction indicated by the arrow X tends to occur. In the present embodiment, the protrusions  34  are thus provided to extend in the direction indicated by the arrow Y, thereby making the occurrence of uneven deformation when viewed from the direction indicated by the arrow X more difficult. 
         [0032]    The protrusions  34  formed on the metal covers  31  are not limited to those formed by folding a thin plate. For example, it is also possible to project projection formed on the thin plate. The width of the magnets  32  in the direction indicated by the arrow X can be formed to be smaller than the width between the protrusions  34  that are adjacent to each other. Although the magnets  32  are not tightly fitted between the protrusions  34  that are adjacent to each other, the effect of reducing the displacement of the magnets  32  is still expected in the direction indicated by the arrow X by fixing the magnets  32  to the metal covers  31  with an adhesive or the like. 
         [0033]      FIG. 7  is an exploded perspective view of the mover  30  according to a first modification. In the first modification, the reinforcing parts  33  are provided only on one side of the magnets  32 . Accordingly, reduction in the weight of the mover  30  can be achieved by a smaller number of the reinforcing parts  33  than in a case where the reinforcing parts  33  are provided on both sides of the magnets  32 . 
         [0034]    The magnets  32  and the reinforcing parts  33  are provided to be in contact with each other. The total length of the magnet  32  and the reinforcing part  33  is substantially equal to the width of the metal covers  31  in the direction indicated by the arrow Y. This facilitates positioning when the magnets  32  and the reinforcing parts  33  are provided on the metal covers  31 . Even in a case where most of the area except for the magnets is occupied by the reinforcing parts  33  as illustrated in  FIG. 7 , further reduction in the weight when compared to the mover configured by fitting the magnets in an aluminum block can be achieved by the use of a material having a lower specific gravity than that of aluminum as the reinforcing parts  33 . 
         [0035]    For example, by providing the reinforcing parts  33  so as to align one end thereof with one end of the metal covers  31  and then providing the magnets  32  so as to be in contact with the reinforcing parts  33 , the magnets  32  and the reinforcing parts  33  can be positioned. Accordingly, it is unnecessary to make marks or uneven portions for positioning on the metal covers  31 , the magnets  32 , nor the reinforcing parts  33 . The same holds true for a case where the reinforcing parts  33  are provided on both sides of the magnets  32 , as illustrated in  FIG. 3 , and by providing the magnets  32  so as to be in contact with the reinforcing parts  33 , the magnets  32  and the reinforcing parts  33  can be easily positioned. 
         [0036]      FIG. 8  is an exploded perspective view of the mover  30  according to a second modification. In the second modification, the reinforcing parts  33  are provided only on one side of the respective magnets  32 , which is similar to the first modification. Accordingly, reduction in the weight of the mover  30  can be achieved by having a smaller number of the reinforcing parts  33  than in a case where the reinforcing parts  33  are provided on both sides of the magnets  32 . Furthermore, by providing gaps between the magnets  32  and the reinforcing parts  33 , the weight can be reduced by the part that would be occupied by the gaps. 
       INDUSTRIAL APPLICABILITY 
       [0037]    As described above, the mover according to the present invention is useful in a mover that includes magnets. 
       REFERENCE SIGNS LIST 
       [0038]      10  stationary part,  11  stationary base,  12  magnetic-field generating unit,  13  guide rail,  30  mover, metal cover,  31   a  through hole,  32  magnet,  33  reinforcing part,  33   a  through hole,  34  protrusion,  35  linear guide,  50  linear motor.