Abstract:
An aspect of the present invention provides an electric magnet device, in which a smooth movement of an armature is ensured and, even if a vibration or an impact is applied, an attraction state between a yoke and the armature is maintained to prevent a malfunction, and a switch provided therewith, where the electric magnet device includes: a coil adapted to insert through an armature and a yoke so as to attract surfaces of the yoke and the armature, which are opposed to each other, to receive a voltage, to excite for separating the surfaces of the yoke and the armature; the armature disposed on one end side of the coil; and the yoke disposed on the other end side of the coil and adapted to oscillate, such that an oscillation angle of the yoke is greater than that of the armature.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims benefit of priority to Japanese Patent Application No. 2012-199680, filed on Sep. 11, 2012 of which the full contents are herein incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an electric magnet device. 
         [0003]    A conventional electric magnet device, for example, Japanese Unexamined Patent Publication No. 2001-135521 discloses an electric magnet device in which a distance between centers of a pair of leg parts formed in an armature is made less than a distance between centers of bobbin holes. The electric magnet device has a structure in which the leg parts abut on an inside surface of the bobbin holes, such that an external force is applied from a predetermined direction to move the armature in the predetermined direction. The armature turns about an end portion of the inside surface with a small turning angle. Therefore, the armature hardly drops off from the yoke to improve an impact resistance. 
         [0004]    However, in the electric magnet device, there has been a problem that when the distance between the centers of the leg parts is excessively less than the distance between the centers of the bobbin holes due to a variation of working accuracy of a component, the leg part has a difficulty in moving in the bobbin hole. 
         [0005]    The invention provides smooth movement of the armature inside the bobbin and, maintains an attraction state between the yoke and the armature within the electric magnet device. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with one aspect of an electric magnet device, the electric magnet device includes: a coil adapted to insert through at least one armature and a yoke so as to attract surfaces of the yoke and the armature which are opposed to each other, to receive a voltage, to excite for separating the surfaces of the yoke and the armature; the armature disposed on one end side of the coil and adapted to oscillate; and the yoke disposed on the other end side of the coil and to oscillate, wherein an oscillation angle of the yoke is greater than an oscillation angle of the armature. 
         [0007]    According to an embodiment of the present invention, a ratio of the oscillation angle of the yoke to the oscillation angle of the armature may be greater than 1:1 and less than or equal to 3:1. 
         [0008]    According to another embodiment of the present invention, attraction surfaces of the armature and the yoke are having a square shape. 
         [0009]    According to a different embodiment of the present invention, attraction surfaces of the armature and the yoke may are having a circular shape. 
         [0010]    According to still another embodiment of the electric magnet, the yoke includes an assembly notch in each of both lateral edge portions of the yoke. 
         [0011]    The invention further provides a switch including the electric magnet device described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view illustrating a switch incorporating an electric magnet device according to a first embodiment of the present invention; 
           [0013]      FIG. 2  is an exploded perspective view of the switch in  FIG. 1 ; 
           [0014]      FIG. 3  is an exploded perspective view of the switch in  FIG. 1  when viewed from a direction different from that in  FIG. 2 ; 
           [0015]      FIG. 4  is a perspective view illustrating an electric magnet device of an embodiment of the present invention; 
           [0016]      FIG. 5  is an exploded perspective view of the electric magnet device in  FIG. 4 ; 
           [0017]      FIG. 6A  is a front sectional view illustrating the switch before an operation; 
           [0018]      FIG. 6B  is a side sectional view illustrating the switch in  FIG. 6A ; 
           [0019]      FIG. 7A  is a front sectional view illustrating the switch after the operation; 
           [0020]      FIG. 7B  is a side sectional view illustrating the switch in  FIG. 7A ; 
           [0021]      FIG. 8  is a side sectional view illustrating the switch in a state in which an armature is inclined during the operation; 
           [0022]      FIG. 9  is a schematic diagram illustrating an electric magnet device according to a second embodiment of the present invention; and 
           [0023]      FIG. 10  is a schematic diagram illustrating an electric magnet device according to a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    A reset-function-equipped switch  1  incorporating an electric magnet device according to a first embodiment of the present invention is described with reference to the accompanying drawings of  FIGS. 1 to 8 . 
         [0025]    As illustrated in  FIGS. 1 to 3 , the switch  1  includes a housing  10 , an operation piece  13 , a power switch mechanism  20 , and a drive mechanism  40 . 
         [0026]    The housing  10  has a box shape with an upper portion being opened, and the housing  10  is configured such that the power switch mechanism  20  is disposed on one side of its inner space while the drive mechanism  40  is disposed on the other side of the inner space. 
         [0027]    The operation piece  13  has a substantially rectangular box shape with a lower surface being opened, and the operation piece  13  includes an operation surface  14 , a support shaft  15 , a retention part  16  (see  FIG. 6A ), and an abutment plate  17  (see  FIG. 6A ). The operation surface  14  is formed as a curved surface on the upper surface of the operation piece  13 . The support shaft  15  protrudes outward from center of both side surfaces, opposite to each other, of the operation piece  13 . The retention part  16  protrudes downward from center of a backside of the operation surface  14 , and a coupling body  21  is fitted in and retained by the retention part  16 . The abutment plate  17  protrudes downward from an end portion of the backside of the operation surface  14 , and abuts on an upper end of an armature  71 . The support shaft  15  is fitted in a circular hole  11  of the housing  10 , whereby the operation piece  13  is mounted to the housing  10  so as to be turnable about the support shaft  15 . 
         [0028]    The power switch mechanism  20  includes a first power switch mechanism  20   a  and a second power switch mechanism  20   b,  which are disposed in parallel in the housing  10 . The first and the second power switch mechanism  20   a,    20   b  includes the coupling body  21 , a movable contact piece  23 , a first fixed contact piece  31 , and a second fixed contact piece  34 . 
         [0029]    The coupling body  21  is composed of a coil spring bent into a chevron shape. As illustrated in  FIG. 6A , with the switch  1  being assembled, an upper end portion of the coupling body  21  is fitted in and retained by the retention part  16  of the operation piece  13 , and a lower end portion of the coupling body  21  is inserted in and supported by a protrusion  25  of a movable contact piece  23 . 
         [0030]    As illustrated in  FIG. 3 , the movable contact piece  23  includes a support part  24  bent into a substantial L-shape and a tongue piece  27  that extends obliquely upward from the end portion of the support part  24 . The chevron-shape protrusion  25  that protrudes upward is formed in a horizontal surface of the support part  24 . A movable contact  28  is provided at a leading end of the tongue piece  27 . 
         [0031]    A first fixed contact piece  31  has a vertically reverse L-shape, and a first fixed contact  32  is formed in the upper surface of the first fixed contact piece  31  by cutting and raising the first fixed contact piece  31 . Similarly, a second fixed contact piece  34  has a vertically reverse L-shape, and a second fixed contact  35  is attached to the upper surface of the second fixed contact piece  34 . Because the second power switch mechanism  20   b  is composed of the same components as the first power switch mechanism  20   a,  the same component is designated by the same numeral, and the description thereof is omitted. 
         [0032]    As illustrated in  FIGS. 4 and 5 , the drive mechanism  40  includes an electric magnet device  41 , a case  60 , a return spring  75 , and a cover  77 . 
         [0033]    The electric magnet device  41  includes a bobbin  43  that includes a vertically piercing through-hole  42 , a coil  48  that is wound around the bobbin  43 , a yoke  50  that is inserted through the through-hole  42  of the bobbin  43  from below, and the armature  71  that is inserted through the through-hole  42  of the bobbin  43  from above. 
         [0034]    The bobbin  43  includes two coil-winding parts  44  provided in parallel, an upper end edge part  45 , and a lower end edge part  46 . The coil winding part  44  is cylindrical having a rectangular shape in section, and the coil  48  is wound around an outer periphery of the coil winding part  44 . The upper end edge part  45  is formed at the upper end of the coil winding part  44 , and the upper end edge part  45  integrally connects the two coil winding parts  44 . The lower end edge part  46  is composed of a rectangular frame body formed at the lower end of each coil winding part  44 , a reset signal input terminal  55  to which a bound leads of the coil  48  is connected is press-fitted in and fixed to the lower end edge part  46 . 
         [0035]    The yoke  50  is made of a plate-like magnetic material that enhances magnetic efficiency of a permanent magnet  56  (to be described). The yoke  50  also includes a pair of upwardly extending arm parts  51 , a pair of notches  52  that are formed on the lower side of the lateral surface and curved inward into a U-shape, and a linear attaching hole  53  that is formed in the center so as to extend vertically. The rectangular-solid-shape permanent magnet  56  is fitted in and fixed to the he attaching hole  53 . 
         [0036]    The case  60  includes a storage part  61  in which the electric magnet device  41  is stored, a pair of guide plates  62  formed above the storage part  61 , and a socket  63  formed below the storage part  61 . An upper-side latching protrusion  65  and a lower-side latching protrusion  66 , which protrude outward, are formed in both side surfaces of the case  60 . An insertion hole  67  (see  FIG. 6A ) is made in a ceiling surface of the storage part  61 , through which the armature  71  is inserted the storage part  61  between the guide plates  62 . A pair of linear protrusions  68  extending vertically from the upper side, a plate-like protrusion  69  extending horizontally in the center, and a curved protrusion  70  including a curved surface protruding inward on the lower side are formed on an inward surface on deep side of the storage part  61 . The socket  63  detachably retains a reset signal input plug (not illustrated) connected to the reset signal input terminal  55 . 
         [0037]    As illustrated in  FIG. 5 , the armature  71  is formed into a gate-type plate shape, and includes step parts  72  that are formed at an upper edge of the armature  71  to protrude toward both the sides and a pair of downwardly extending leg parts  73 . With the drive mechanism  40  being assembled, the return spring  75  is retained in a compressed state between the step part  72  of the armature  71  and the upper surface of the storage part  61 . Therefore, the return spring  75  pushes up the armature  71  to maintain the operation piece  13  at an off state in which the operation piece  13  is turned in an off direction. 
         [0038]    The cover  77  has a lateral shape that can laterally be fitted in the case  60 , and includes a pair of upper-side elastic arm parts  78  extending in parallel from both side edge portions on the upper side and a pair of lower-side elastic arm parts  79  extending in parallel from both side edge portions on the lower side. A horizontally extending upper-side latching hole  81  is made in the upper-side elastic arm part  78 . A horizontally extending lower-side latching hole  82  is made in the lower-side elastic arm part  79 . 
         [0039]    A method for assembling the drive mechanism  40  will be described as a preceding process of assembling the switch  1 . The lead of the coil  48  wound around the outer peripheral surface of the coil winding part  44  of the bobbin  43  is bound and soldered to the reset signal input terminal  55  fixed to the lower end edge part  46 . The permanent magnet  56  is fitted in the attaching hole  53  of the yoke  50 , and the arm part  51  is inserted through the through-hole  42  of the bobbin  43  from below, thereby forming the electric magnet device  41  except the armature  71 . Because the notch  52  is provided in the yoke  50 , the yoke  50  can easily be gripped with a tool through the notch, thereby improving workability. 
         [0040]    Then the electric magnet device  41  is stored in the storage part  61  of the case  60 . At this point, the upper end edge part  45  of the bobbin  43  abuts on the linear protrusion  68 , and abuts on the ceiling surface of the storage part  61 . Additionally, the lower end edge part  46  abuts on the upper side surface of the plate-like protrusion  69 , whereby the electric magnet device  41  is positioned in the storage part  61  (case  60 ). At this point, the yoke  50  is retained and fitted in the storage part  61  with a play, so that the yoke  50  can oscillate with the arm part  51  being inserted through the through-hole  42 . Accordingly, surface contact between the arm part  51  and the leg part  73  of the armature  71  is facilitated. As illustrated in  FIG. 6A , because the yoke  50  is sucked to the reset signal input terminal  55  by a magnetic force of the permanent magnet  56 , the yoke  50  floats from a bottom portion of the case  60  with a predetermined gap. 
         [0041]    Then the cover  77  is mounted to the case  60  so as to cover the opening lower side of the case  60  and the socket  63 . At this point, the upper-side latching hole  81  of the cover  77  is latched in the upper-side latching protrusion  65  of the case  60 , and the lower-side latching hole  82  is latched in the lower-side latching protrusion  66 , thereby retaining the electric magnet device  41 . Finally the armature  71  is inserted through the through-hole  42  of the bobbin  43  through the insertion hole  67  of the case  60  while the return spring  75  disposed above the storage part  61  is interposed between the armature  71  and the through-hole  42 , thereby completing the drive mechanism  40 . 
         [0042]    Then, as illustrated in  FIG. 3 , the first fixed contact pieces  31  and the second fixed contact pieces  34  are inserted in and attached to terminal holes (not illustrated) made in the bottom surface of the housing  10 . The bottom surface of the support part  24  of the movable contact piece  23  is turnably placed on the first fixed contact  32  of the first fixed contact piece  31 . The lower end of the coupling body  21  is inserted in the protrusion  25  of the movable contact piece  23 , and the retention part  16  of the operation piece  13  is fitted in the upper end of the coupling body  21 . The support shaft  15  of the operation piece  13  is fitted in the circular hole  11  of the housing  10 , and the support shaft  15  of the operation piece  13  is turnably attached to the housing  10 . Therefore, the power switch mechanism  20  is completed. Finally, as illustrated in  FIGS. 6 , the drive mechanism  40  is incorporated from below on the other side of the housing  10  in which the power switch mechanism  20  is incorporated, and the switch  1  is completed. 
         [0043]    An operation of the switch  1  will be described below. 
         [0044]    As illustrated in  FIGS. 6A and 6B , when the power switch mechanism  20  is in the off state, the return spring  75  extends to bias the armature  71  upward. Therefore, the upper end surface of the armature  71  pushes up the abutment plate  17 , and the operation piece  13  is in the off state. In the off state, the coupling body  21  of the power switch mechanism  20  is bent into the chevron shape toward the side of the drive mechanism  40 . The movable contact  28  of the movable contact piece  23 , which turns with the upper end of the first fixed contact  32  as a support point, separates from the second fixed contact  35 , and is in the off state. 
         [0045]    As illustrated in  FIGS. 7A and 7B , when the side of the abutment plate  17  of the operation surface  14  is pressed downward to turn on the switch  1 , the abutment plate  17  pushes down the armature  71  against a biasing force of the return spring  75 . Therefore, the armature  71  moves downward, the leg part  73  is attracted to the arm part  51  of the yoke  50  due to the magnetic force of the permanent magnet  56  interposed between opposite surfaces of the arm part  51 , and the switch  1  becomes the on state. 
         [0046]    When the switch  1  is turned on, the coupling body  21  of the power switch mechanism  20  is bent into the chevron shape toward the opposite side to the drive mechanism  40 . Therefore, the protrusion  25  is pressed onto the right side in  FIG. 7 , and the movable contact piece  23  turns clockwise in  FIG. 7  about the upper end of the first fixed contact  32 . The movable contact  28  abuts on the second fixed contact  35  to turn on the power. 
         [0047]    As illustrated in  FIG. 8 , in the present invention, the yoke  50  is attached to and fitted in the bobbin  43  with the play, so that the yoke  50  can be inclined according to an inclination of the armature  71 . Accordingly, the leg part  73  and the arm part  51  come into surface contact with each other to decrease a magnetic resistance, and the leg part  73  and the arm part  51  can be attracted to each other with the large attractive force. Therefore, even if a vibration or an impact is applied, the attraction state between the leg part  73  and the arm part  51  can be maintained to prevent the malfunction. 
         [0048]    In the embodiment of the present invention, a ratio of an oscillation angle of the yoke  50  to an oscillation angle of the armature  71  is preferably greater than 1:1 and less than or equal to 3:1. When the ratio of the oscillation angles of the yoke  50  to the armature  71  is less than or equal to 1:1, that is for example, 1:0.5, the leg part  73  and the arm part  51  can not be come into surface contact with each other, and the desired effect cannot be obtained. When the ratio of the oscillation angles of the yoke  50  to the armature  71  is greater than 3:1, that is for example, 4:1, in attracting the armature  71  and the yoke  50  to each other, the lower end portion of the leg part  73  comes into contact with an upper-end corner portion of the arm part  51 , and an attraction surface on the side of the armature  71  is abraded to degrade the attractive force. Accordingly, when the ratio of the oscillation angle of the yoke  50  to the oscillation angle of the armature  71  is greater than 1:1 and less than or equal to 3:1, the leg part  73  and the arm part  51  come surely into surface contact with each other, and the abrasions of the attraction surfaces of the leg part  73  and the arm part  51  can be controlled to prevent the degradation of the attractive force. In the present embodiment, the attraction surfaces of the leg part  73  and the arm part  51  are formed into the square shape, but are not limited thereto. The same effect is obtained even if the attraction surfaces of the leg part  73  and the arm part  51  are formed into a circular shape. The square shape or the circular shape of the attraction surfaces enhances a degree of design freedom. 
         [0049]    When a voltage that generates the reverse magnetic force is applied to the coil  48  through the reset signal input terminal  55  in order to turn off the switch  1  in the on state, a magnetic flux of the permanent magnet  56  is canceled to relatively lower the magnetic force between the armature  71  and the yoke  50 . Therefore, the armature  71  is pushed upward by the elastic force of the return spring  75 , and the upper end surface of the armature  71  pushes up the abutment plate  17 . As a result, the operation piece  13  turns about the support shaft  15 , and the power switch mechanism  20  returns to the off state illustrated in  FIG. 6A . 
         [0050]    The present invention is not limited to the above embodiment, but various modifications can be made. In the above embodiment, as to the yoke  50  and the armature  71 , the arm part  51  and the leg part  73  are inserted through the through-hole  42  of the bobbin  43 , but not limited thereto. Alternatively, for example, in an electric magnet device according to a second embodiment illustrated in  FIG. 9 , a plate-like yoke  85  is disposed on the lower end part of the coil  48 , an armature  87  including a pair of downwardly extending leg parts  86  is disposed on the upper end part of the coil  48 . For the sake of convenience, the bobbin  43  is omitted in this electric magnet device. The armature  87  is moved downward so that the lower end surfaces of the leg parts  86  are inserted through inside the coil  48  to be attracted to the upper surface of the yoke  85 . At this point, because the yoke  85  is attached to and fitted in the case  60  with the play, the yoke  85  can be inclined according to the inclination of the armature  87 , and the leg part  86  can come into surface contact with the yoke  85 . 
         [0051]    As another example, in an electric magnet device according to a third embodiment illustrated in  FIG. 10 , a yoke  91  including a pair of upwardly extending arm parts  90  inserted through inside the coil  48  is disposed on the lower end part of the coil  48 , and a plate-like armature  92  is disposed on the upper end part of the coil  48 . For the sake of convenience, the bobbin  43  is omitted in this electric magnet device. The lower surface of the armature  92  is attracted to the upper end surface of the arm part  90  by moving the armature  92  downward. At this point, because the yoke  91  is attached to and fitted in the case  60  with the play, the yoke  91  can be inclined according to the inclination of the armature  92 , and the armature  92  can come into surface contact with the arm part  90 . 
         [0052]    The electric magnet device  41  of the first embodiment includes the pair of coils  48 , the yoke  50  including the pair of arm parts  51 , and the armature  71  including the pair of leg parts  73 , but not limited thereto. Alternatively, for example, a configuration in which the electric magnet device includes the one coil, the yoke includes the one arm part, and the armature includes the one leg part may be employed. The electric magnet device of the present invention can of course be applied not only to the switch but also to other electric instruments. 
         [0053]    There has thus been shown and described an electromagnetic device and switch using the same which fulfills all the advantages sought therefore. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is to be limited only by the claims which follow. 
         [0054]    Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.