Abstract:
An electromagnet device has a movable iron piece having an end that is operable to contact and separate to and from a magnetic pole portion of an iron core. The movable iron piece rotates based on magnetization and demagnetization of a coil wound around the iron core. A tapered surface is formed on at least one end of an attraction surface of the movable iron piece, which attracts to and separates from the magnetic pole portion of the iron core. At least one contacting portion that is in flush with and continuous to the attraction surface and in contact with the magnetic pole portion of the iron core is arranged in a projecting manner on the tapered surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to an electromagnet device, in particular, to a shape of a movable iron piece of the electromagnet device used in an electromagnetic relay 
         [0003]    2. Related Art 
         [0004]    Conventionally, for a movable iron core of an electromagnet device, the electromagnet device in which an end of the movable iron piece, which rotates based on magnetization and demagnetization of a coil wound around an iron core, is arranged to contact with or separate from a magnetic pole portion of the iron core, and a movable contact spring piece integral with the movable iron piece is driven to open/close a contacting point is known (refer to, for example, Japanese Patent Publication No. 3413847). 
         [0005]    However, the movable iron piece of the electromagnet device has both ends contacting a magnetic pole portion of the iron core formed to a flat surface, where an attraction surface of the movable iron piece contacts the magnetic pole portion of the iron core in area or in line. When the movable iron piece and the magnetic pole portion of the iron core are in contact in area or in line, an attractive force the movable iron piece receives from the electromagnet is greatly influenced by a contacting state such as a contacting angle of the movable iron piece and the magnetic pole portion of the iron core. Thus, a holding force of the movable iron piece varies if the contacting state varies, and thus an opening force required when the movable iron piece opens from the iron core varies, and a stable operation property becomes difficult to obtain. Furthermore, an operation failure, and inoperability tend to easily occur due to an abrasive powder generated when both ends of the movable iron piece attract to or separate from the magnetic pole portion of the iron core, and other foreign substances. 
         [0006]    In order to solve such problems, a projection  2  is arranged in a projecting manner at an end of a movable iron piece  1  to be attracted to the magnetic pole portion of the iron core, as shown in  FIGS. 6A and 6B . When forming the projection  2 , the end of the movable iron piece  1  is normally positioned in a die formed with a mortar-shaped recess, and the projection  2  is formed through extrusion processing. 
         [0007]    However, since oil, dust, and the like easily attach to an inside of the recess of the die, a height dimension M of the projection  2  tends to vary. In particular, variations in the height dimension M become relatively large if the height dimension M of the projection  2  is very small. Thus, an adjustment task in an assembly step requires great trouble as variations in an operation property due to the variations in the height dimension M is to be resolved, and a production cost tends to increase. 
         [0008]    As shown in  FIGS. 6C and 6D , a proposal has been made to arrange the projection  2  in a projecting manner at a step  3  one step lower than an attraction surface of a movable iron piece  1 . However, in order to form the step  3  of one step lower, a large piece of equipment is required according to an area and a crushing amount of the step  3 , and furthermore, a processing man-hour increases and the production cost increases. 
       SUMMARY 
       [0009]    In view of the above problems, it is an object of the present invention to provide an electromagnet device in which the height dimension of a contacting portion of the movable iron piece does not have variations, an adjustment of an operation property is unnecessary, and a production cost is low. 
         [0010]    To solve the above problem, an electromagnet device according to the present invention relates to an electromagnet device for contacting and separating an end of a movable iron piece, which rotates based on magnetization and demagnetization of a coil wound around an iron core, to and from a magnetic pole portion of the iron core; wherein a tapered surface is formed on at least one end of an attraction surface of the movable iron piece, which attracts to and separates from the magnetic pole portion of the iron core, and at least one contacting portion being in flush with and continuous to the attraction surface and in contact with the magnetic pole portion of the iron core is arranged in a projecting manner on the tapered surface. 
         [0011]    According to the present invention, a discontinuous recess does not need to be formed in the die as in the related art since the contacting portion of the movable iron piece is formed in flush with and continuous to the attraction surface. Therefore, the device is less susceptible to an influence of oil, dust, or the like, and the variations in the height dimension is less likely to occur, and thus the operation property of the movable iron piece can be improved, the adjustment task in the assembly step is unnecessary, and the production cost can be reduced. 
         [0012]    Another electromagnet device according to the present invention may relate to an electromagnet device for contacting and separating an end of a movable iron piece, which rotates based on magnetization and demagnetization of a coil wound around an iron core, to and from a magnetic pole portion of the iron core; wherein a tapered surface is formed on at least one end of an attraction surface of the movable iron piece, which attracts to and separates from the magnetic pole portion of the iron core, and at least one recess is formed at the tapered surface to arrange at least one contacting portion being in flush with and continuous to the attraction surface and in contact with the magnetic pole portion of the iron core. 
         [0013]    According to the present invention, effects similar to the above-described aspects of the invention are obtained, and a movable iron piece having a contacting portion of various shapes can be obtained, whereby an application can be extended. 
         [0014]    As an embodiment according to the present invention, the tapered surface may be an are-surface. 
         [0015]    According to this embodiment, a degree of freedom in designing the die can be increased, and manufacturing of the die is facilitated. 
         [0016]    As another embodiment according to the present invention, a contacting portion being in flush with and continuous to the attraction surface may be arranged in a projecting manner at the tapered surface formed at both ends of the attraction surface of the movable iron piece. 
         [0017]    According to this embodiment, an electromagnet device having a seesaw type movable iron piece is obtained, and the application can be extended. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a cross-sectional view showing a case where an electromagnet device of the present invention is applied to an electromagnetic relay; 
           [0019]      FIGS. 2A to 2D  show a perspective view, a plan view, a front view, and a partially enlarged view, each showing a movable iron piece incorporated in the electromagnetic relay shown in  FIG. 1 ; 
           [0020]      FIG. 3A  shows a schematic view for describing a shape of a contacting portion of the movable iron piece, and  FIG. 3B  shows a partially enlarged cross-sectional view showing a state in which a contacting portion of the movable iron piece is brought into contact with a magnetic pole portion of an iron core; 
           [0021]      FIGS. 4A to 4E  show a perspective view, a plan view, a front view, a bottom view, and a right side view, each showing a state in which a pushing spring is assembled to the movable iron piece shown in  FIG. 2 ; 
           [0022]      FIGS. 5A to 5D  are partial perspective views each showing a movable iron piece according to a second, third, fourth, and fifth embodiments; and 
           [0023]      FIGS. 6A and 6B  show a perspective view and a partially enlarged cross-sectional view each showing a movable iron piece according to a related art, and  FIGS. 6C and 6D  show a perspective view and a partially enlarged cross-sectional view each showing a movable iron piece according to another related art. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    An embodiment of the present invention will be described according to the accompanied drawings of  FIGS. 1 to 5 . 
         [0025]    As shown in  FIGS. 1 to 4 , an electromagnet device  50  according to a first embodiment is a case applied to a self-returning type electromagnetic relay used to open/close a high frequency circuit. 
         [0026]    In other words, the electromagnetic relay according to the present embodiment has the electromagnet device  50 , in which a movable iron piece  70  is assembled to an electromagnet block  60 , incorporated in a space formed by fitting and integrating a case  90  to a base block  10 . 
         [0027]    The base block  10  is obtained by sandwiching a base  11 , which incorporates a pair of movable contacting point blocks  30 ,  35 , from above and below by a lower shield plate  20  and an upper shield plate  40 . 
         [0028]    The base  11  is arranged with a common fixed contacting point portion  12   a,  a constantly opened fixed contacting point portion  13   a,  and a constantly closed fixed contacting point portion  14   a  by insert molding a common fixed contacting point terminal  12 , a constantly opened fixed contacting point terminal (not shown), and a constantly closed fixed contacting point terminal (not shown) cut out from a lead frame (not shown). 
         [0029]    The lower shield plate  20  forms an upstanding wall (not shown) by punching out a conductive plate-shaped body through press working, and bending and raising a peripheral edge portion so as to be connectable to an upper shield plate  40 , to be hereinafter described. Furthermore, the lower shield plate  20  has a return spring  21  welded and integrated at a central part of a bottom surface. Ends  22 ,  23  of the return spring  21  are respectively pressure contacted to lower end faces of the movable contacting point blocks  30 ,  35 , to be hereinafter described, and biased to an upper side. 
         [0030]    The movable contacting point blocks  30 ,  35  are obtained by insert molding each movable contacting pieces  31 ,  36  made from conductive plate spring. The ends of the movable contacting piece  31  can be brought into contact with and separated from the common fixed contacting point portion  12   a  and the constantly opened fixed contacting point portion  13   a.  The ends of the movable contacting piece  36  can be brought into contact with and separated from the common fixed contacting point portion  12   a  and the constantly closed fixed contacting point portion  14   a.    
         [0031]    The upper shield plate  40  is made of a conductive material of a rectangular plate shape, where the upper ends of the movable contacting point blocks  30 ,  35  project out in a freely upward and downward moving manner from insertion holes  41 ,  43  formed at two locations in a longitudinal direction. The upper shield plate  40  is arranged in a projecting manner with earth contacting point portions  42 ,  42  at positions facing each other with the insertion hole  41  in between, and is arranged in a projecting manner with earth contacting point portions  44 ,  44  at positions facing each other with the insertion hole  43  in between. A plurality of earth terminals  45  are extended downward from the peripheral edge portion at the upper shield plate  40 . 
         [0032]    The electromagnetic block  60  is formed by winding a coil  63  to a spool  62  assembled with an iron core  61  and a coil terminal (not shown), and then assembling a permanent magnet  64 . The iron core  61  has a cross-section of a substantially hat shape, where the lower surface of both ends serve as magnetic pole portions  65 ,  66 . 
         [0033]    As shown in  FIGS. 2 to 4 , the movable iron piece  70  is made of a plate-shaped magnetic material, where the central part is subjected to extrusion processing so that a protrusion  71 , which acts as a rotation supporting point, is arranged in a projecting manner on an attraction surface  70   a  side. At tapered surfaces  72 ,  74  formed by press working both ends of the attraction surface  70   a,  the movable iron piece  70  is arranged in a projecting manner with contacting portions  73 ,  75  of a semicircular shape in plane view. 
         [0034]    In particular, as shown in  FIG. 3A , the tapered surface  72  is formed at an inclination angle θ, and the contacting portion  73  is continuous to and in flush with the attraction surface  70   a  of the movable iron piece  70 . As shown in  FIG. 3B , an opposing distance D between the magnetic pole portion  65  of the iron core  61  and the tapered surface  72  of the movable iron piece  70  is determined by the inclination angle θ (=B/A) of the tapered surface  72  and a length dimension C of the contacting portion  73 . That is, 
         [0000]      Height dimension  D  of contacting portion= C ×sin θ 
         [0000]      θ=tan −1 ( B/A ) 
         [0035]    Thus, a press surface for forming the tapered surface  72  merely needs to be formed in a die, and a recess does not need to be formed in the press die as in the related art. As a result, a structure of the die is simplified, variations in the height dimension D of the contacting portions  73 ,  75  are eliminated, and an electromagnetic relay without variations in an operation property is obtained. 
         [0036]    Furthermore, as shown in  FIG. 4 , the movable iron piece  70  is welded and integrated with a pushing spring  80  at the central part of the lower surface. The pushing spring  80  has a substantially cross-shape in plane view, where the opposing ends are bent and raised at a substantially right angle to form supporting projections  81 ,  81 . The supporting projection  81  has a substantially triangular shape in front view so as to be automatically aligned, and a vertex thereof is arranged on the same line as the vertex of the protrusion  71  of the movable iron piece  70 . Thus, an advantage in that a rotation of the movable iron piece  70  becomes a smooth rotation is obtained. Press working is performed on the remaining opposing ends of the pushing spring  80  to form elastic arms  82 ,  83 . 
         [0037]    An operation of the electromagnetic relay configured as above will be described. 
         [0038]    First, if voltage is not applied to the coil  63 , the contacting portion  73  positioned at one end of the movable iron piece  70  is brought into contact with the magnetic pole portion  65  of the iron core  61  by a magnetic force of the permanent magnet  64 . Thus, the elastic arm  83  of the pushing spring  80  pushes down the movable contacting point block  35 . As a result, both ends of the movable contacting piece  36  are brought into contact with the common fixed contacting point portion  12   a  and the constantly opened fixed contacting point portion  14   a  against the spring force of the other end  23  of the return spring  21 . The movable contacting point block  30  is biased to the upper side by one end  22  of the return spring  21 , and both ends of the movable contacting piece  31  are respectively brought into contact with the earth contacting point portions  42 ,  42  of the upper shield plate  40 . 
         [0039]    If a voltage is applied to the coil  63  in a direction of canceling out a magnetic flux of the permanent magnet  64 , the magnetic pole portion  66  of the iron core  61  attracts the other end of the movable iron piece  70 , and the movable iron piece  70  rotates with the vertex of the protrusion  71  as the rotation supporting point. The elastic arm  82  of the pushing spring  80  thus pushes down the movable contacting point block  30  against the spring force of one end  22  of the return spring  21 . As a result, the movable contacting point block  30  lowers, and both ends of the movable contacting piece  31  respectively come into contact with the common fixed contacting point portion  12   a  and the constantly opened fixed contacting point portion  13   a.  The movable contacting point block  35  is pushed up by the spring force of the other end  23  of the return spring  21 , and both ends of the movable contacting piece  36  respectively open from the common fixed contacting point portion  12   a  and the constantly closed fixed contacting pint portion  14   a,  and then come into contact with the earth contacting point portions  44 ,  44  of the upper shield plate  40 . Thereafter, the contacting portion  75  of the movable iron piece  70  is attracted to the magnetic pole portion  66  of the iron core  61 . 
         [0040]    When application of the voltage to the coil  63  is stopped, a magnetic balance of the electromagnet device  50  is imbalanced, where the attractive force by the magnetic pole portion  65  of the iron core  61  is stronger than the attractive force by the magnetic pole portion  66 . Thus, the movable iron piece  70  rotates in the direction opposite to the above and the elastic arm  83  of the pushing spring  80  pushes down the movable contacting point block  35 , where one end  22  of the return spring  21  pushes up the movable contacting point block  30 . As a result, both ends of the movable contacting piece  36  are brought into contact with the common fixed contacting point portion  12   a  and the constantly closed fixed contacting point portion  14   a,  whereas both ends of the movable contacting piece  31  are brought into contact with the earth contacting point portions  42 ,  42  of the upper shield plate  40  and return to the original state. 
         [0041]    As another embodiment of the movable iron piece  70 , a pair of contacting portions  73 ,  73  of a semicircular shape in plane view may be arranged side by side at the tapered surface  72  (a second embodiment), as shown in  FIG. 5A ; the contacting portion  73  of a triangular shape in plan view may be formed at the tapered surface  72  (a third embodiment), as shown in  FIG. 5B ; or the contacting portion  73  of a square shape in plan view may be formed at the tapered surface  72  (a fourth embodiment), as shown in  FIG. 5C . Furthermore, a recess  76  may be formed at the central part of the tapered surface  72 , as shown in  FIG. 5D  to form a pair of contacting portions  73 ,  73  at both side edge portions of the tapered surface  72  (a fifth embodiment). 
         [0042]    The electromagnet device is not limited to a device including a seesaw type movable iron piece, and may be a pulsating-type movable iron piece. The contacting portion is not limited to being arranged at both ends of the movable iron piece, and may be arranged at only one end, or may be respectively arranged at the ends on the front and back surfaces of the movable iron piece. 
         [0043]    It should be apparent that the electromagnet device according to the present invention is not limited to being applied to the electromagnetic relay, and may also be applied to other electric equipment.