Abstract:
A core for an electromagnetic device includes a yoke and at least two legs extending from the yoke. The yoke and at least two legs are formed of steel plates laminated together. Each of the legs has a free end face forming a magnetic pole face, a first groove extending from the magnetic pole face and a second magnetic groove on a side face thereof. Also, the core includes a shading coil having a metal ring shape, and including a first linear section and a second linear section extending in parallel with each other. A part of the first linear section is accommodated in the first groove, and a part of the second linear section is accommodated in the second groove and locked therein. A bottom face of the second groove forms an angle with respect to a bottom face of the first groove.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
       [0001]    The present invention relates to an electromagnet device mounted on a unit such as an electromagnetic contactor and an electromagnetic contactor provided with an electromagnet device and particularly to a device such as an electromagnet device having a core provided with a shading coil. 
         [0002]    First, an example of an electromagnet device will be explained which has a core provided with a shading coil. A shading coil is a coil provided in a single-phase AC electromagnet for suppressing variations in an electromagnetic attractive force due to variations in alternating magnetic flux together with noises and vibrations. 
         [0003]      FIGS. 5A and 5B  are views schematically showing an example of an electromagnet device.  FIG. 5A  is a front view in which the electromagnet device is viewed from the direction orthogonal to both of the direction of driving a movable core and the direction of arranging legs forming each of the movable and a stationary core, and  FIG. 5B  is a view showing the section  5 B in  FIG. 5A  with the section  5 B being enlarged. 
         [0004]    As shown in  FIG. 5A , the electromagnet device  101  includes constituents such as a stationary core  110 , a movable core  120 , an operating coil  130  and a shading coil  140 . Each of the stationary core  110  and the movable core  120  is an E-shaped core formed with approximately E-shaped flat rolled silicon steel sheets laminated and secured by rivets  119 . The E-shaped stationary core  110  has a central leg  111  and a pair of outside legs  112  so that the central leg  111  is located between the pair of outside legs  112 , thereby forming the E-shape. The E-shaped movable core  120  has a central leg  121  and a pair of outside legs  122  so that the central leg  121  is located between the pair of outside legs  122 , thereby forming the E-shape. The stationary core  110  and the movable core  120  are arranged so that a magnetic pole face  112   a  of the outside leg  112  at each end of the stationary core  110  and a magnetic pole face  122   a  of the outside leg  122  at each end of the movable core  120  face each other and are supported so that the magnetic pole faces  112   a  and  122   a  are made butted against each other and made separated from each other. When the magnetic pole faces  112   a  of the outside leg  112  and the magnetic pole faces  122   a  of the outside leg  122  are made butted against each other, a gap is formed between an end face  111   a  of the central leg  111  and an end face  121   a  of the central leg  121 . The reason for this configuration is to prevent the movable core  120  from returning to its original position while being kept attracted to the stationary core  110  by residual magnetic flux when a current supplied to the operating coil  130  is cut off. The operating coil  130  is wound around the central leg  111  of the stationary core  110 . By turning on and off energization of the operating coil  130 , the movable core  120  is butted against and separated from the stationary core  110 . 
         [0005]    The shading coil  140  is provided around the magnetic pole face  112   a  of each outside leg  112  of the stationary core  110 . The shading coil  140  is integrally formed by stamping out an approximately square frame from a metal plate of aluminum alloy, for example. 
         [0006]    As is shown in  FIG. 5B , each of the outside legs  112  of the stationary core  110  has parallel cut grooves  115 ,  117  on the magnetic pole face  112   a  and a face  112   b  of a protrusion  113  on the outside of the outside leg  112 , respectively. The cut grooves extend in the direction of the thickness of the stationary core  110  (in the direction orthogonal to the paper in  FIG. 5B ). The shading coil  140  is inserted into the cut grooves  115 ,  117  to be fastened to the outside leg  112  by press fitting or upsetting (squeezing). 
         [0007]    Incidentally, in an electromagnet, the relation in an electromagnetic attractive force (F) and a magnetic pole area (S) is expressed by the following equation Eq. 1: 
         [0000]      F= B   2 S  (Eq. 1) 
         [0000]    where B represents a magnetic flux density. 
         [0008]    For securing a necessary electromagnetic attractive force with the magnetic flux density made constant, a magnetic pole area is required to have a sum of an area S 1  of a magnetic pole face  112   a - 1  and an area S 2  of a magnetic pole face  112   a - 2  of the outside leg  112 . The magnetic pole face  112   a - 1  is a magnetic pole face between the central leg  111  side surface of the outside leg  112  and the central leg  111  side surface of the cut groove  115  on the inside. The magnetic pole face  112   a - 2  is a magnetic pole face between the cut grooves  115  and  117 . Namely, a face  112   b  on the protrusion  113  on the outside of the outer cut groove  117  does not function as a magnetic pole face necessary for producing an electromagnetic attractive force, but is provided only for arranging and securing the shading coil  140 . For providing such a structure, the protrusion  113  is formed on the outside surface of each of the outside legs  112  to protrude outward. By providing such protrusion  113 , the stationary core  110  is upsized. 
         [0009]    For obtaining a necessary electromagnetic attractive force in such an electromagnet device  101 , the magnetic pole area of S 1 +S 2  must be secured. Furthermore, from the view point of minimizing an iron loss, the cross-sectional areas in a magnetic path must be made uniform so that magnetic flux densities become equal at any cross sections in a magnetic circuit. Besides this, when there is a limitation on the outer dimensions of the electromagnet device  101  as in the case where there is a limitation on the dimension of the width of the core, for example, it becomes necessary to increase the number of laminated steel plates forming the core. In this case, the electromagnet is upsized in the direction of the thickness of the core. This increases the amount of material to be used. 
         [0010]    Incidentally, an electromagnet provided with no face  112   b  on the outside of the outer cut groove  117  is also disclosed (see Japanese Unexamined Patent Application Publication No. JP-A-57-199208, for example). The electromagnet is provided with a cut groove in a line on a magnetic pole face of each outside leg and, along with this, provided with a step on the outside edge. A shading coil is inserted into the cut groove and the step to be welded to be secured to the outside leg. In this example, however, a bar-like material is wound in the cut groove and the step in a ring to form the shading coil. The electromagnet has no protrusion on the outside leg, thereby enabling to form without upsizing its core. Nevertheless, there is a problem of taking time in attaching and welding for securing the shading coil that results in poor productivity. Moreover, there is an increase in electric resistance at the section where both ends of the bar-like material for the shading coil are connected, which sometimes degrades the function as the shading coil. 
         [0011]    Moreover, in some cases, in an electromagnet of a type provided with a cut groove and a step on a magnetic pole face like in the electromagnet disclosed in JP-A-57-199208, a shading coil stamped out in an approximately oval shape frame is inserted into the cut groove and the step, and only the coil inserted into the cut groove on the magnetic pole face is squeezed to be secured. In this case, there is a possibility of the shading coil missing by repetitive vibration caused by the driving of the electromagnet device, thereby causing a problem of making desired durability unattainable. 
         [0012]    The invention was made in view of the foregoing problems with an object of providing an electromagnet device being excellent in productivity, capable of downsizing a core and further having well durability, and an electromagnetic contactor provided with such an electromagnet device. 
         [0013]    Further objects and advantages of the invention will be apparent from the following description of the invention. 
       SUMMARY OF THE INVENTION 
       [0014]    The electromagnet device according to the invention includes a core formed approximately in an E-shape by laminating steel plates with a magnetic pole face formed at the top end of each of a plurality of legs of those forming the E-shape, and a shading coil integrally formed by stamping out an approximately ellipsoidal frame having a first linear section and a second linear section almost in parallel with each other from a metal plate. 
         [0015]    Each of the legs of the core with magnetic pole faces formed at their respective top ends has a first groove formed by making the magnetic pole face dented and a second groove formed by making a side face of the leg dented and extending almost in parallel with the first groove. 
         [0016]    Moreover, at least a part of the first linear section and at least a part of the second linear section of the shading coil are contained in the first groove and the second groove, respectively, of the core and are secured to the first groove and the second groove, respectively, by squeezing. 
         [0017]    In the invention, one of the linear sections is inserted into the groove formed on the side face of the core, by which there is no need to provide a protrusion for supporting the shading coil which protrusion is unnecessary for providing a magnetic attractive force. Thus, with the same outer dimension of the core, the area of a magnetic pole and the cross-sectional area of a magnetic circuit can be increased, thereby contributing to generation of a magnetic attractive force. Therefore, without exerting influence on a magnetic attractive force and magnetic loss, the outer dimension of a core can be downsized. If the outer dimension of the core is the same, a magnetic attractive force can be increased. Furthermore, the coil inserted into both of the grooves is secured to the core by squeezing. This enhances the strength for securing the shading coil to the core to prevent the coil from coming off due to vibrations or impacts. Therefore, the durability of the electromagnet device can be enhanced. Furthermore, the shading coil formed by stamping is secured to the core by squeezing, thereby making it unnecessary to bond a coil to the core by winding a bar-like material in the groove of the core around the core and welding, or by winding a wire around the core many times and welding. Therefore, the shading coil can be attached to the core by a relatively simple mechanical procedure, thereby enhancing the productivity. 
         [0018]    The squeezing is a method of bonding two objects in which a mechanical pressure is applied to one (or both) of the two objects to cause plastic deformation for contact bonding. 
         [0019]    An electromagnetic contactor according to the invention includes the above described electromagnet device and at least one pair of contacts driven to be opened and closed by the electromagnet device. 
         [0020]    With the electromagnetic contactor according to the invention, the core of an electromagnet device can be downsized, so that the electromagnetic contactor can be made compact and its durability can be made enhanced. 
         [0021]    As is apparent from the foregoing explanations, according to the invention, there can be provided an electromagnet device being excellent in productivity, being capable of downsizing a core and further having well durability, and an electromagnetic contactor provided with such an electromagnet device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1A  is a front view schematically showing a structure of an electromagnet device according to a first embodiment of the invention with the electromagnet device viewed from the direction orthogonal to both of the direction of driving a movable core and the direction of arranging legs forming each of the movable and a stationary core. 
           [0023]      FIG. 1B  is a cross sectional view showing the section  1 B in  FIG. 1A  with the section  1 B being enlarged. 
           [0024]      FIG. 2  is a perspective view showing the stationary core in the electromagnet device shown in  FIGS. 1A and 1B . 
           [0025]      FIG. 3A  is a cross sectional view showing a dimensional relation between a shading coil and first and second grooves formed in an outside leg of a stationary core for attaching the shading coil thereto. 
           [0026]      FIG. 3B  is a cross sectional view showing the step of pressing each of the first linear section of the shading coil inserted in the first grooves and the second linear section positioned on the side of the second groove by a squeezing tool. 
           [0027]      FIG. 3C  is a cross sectional view showing a state in which the shading coil is attached to the outside leg of the stationary core. 
           [0028]      FIG. 4  is a front view illustrating a structure of an electromagnetic contactor according to a second embodiment of the invention. 
           [0029]      FIG. 5  A is a front view schematically showing an example of a related electromagnet device with the electromagnet device viewed from the direction orthogonal to both of the direction of driving a movable core and the direction of arranging legs forming each of the movable and a stationary core. 
           [0030]      FIG. 5B  is a view showing the section  5 B in  FIG. 5A  with the section  5 B being enlarged. 
           [0031]      FIG. 6  is a cross sectional view showing the section  1 B in  FIG. 1A  according to a further embodiment. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0032]    In the following, explanation will be made in detail about embodiments of the invention with reference to the attached drawings. 
         [0033]      FIGS. 1A and 1B  are views schematically showing a structure of an electromagnet device according to a first embodiment of the invention.  FIG. 1A  is a front view in which the electromagnet device is viewed from the direction orthogonal to both of the direction of driving a movable core and the direction of arranging legs forming each of the movable and a stationary core.  FIG. 1B  is a view showing the section  1 B in  FIG. 1A  with the section  1 B being enlarged. 
         [0034]      FIG. 2  is a perspective view showing the stationary core in the electromagnet device shown in  FIGS. 1A and 1B . 
         [0035]    The electromagnet device  1  shown in  FIGS. 1A and 1B  is, like the electromagnet device shown in  FIGS. 5A and 5B , formed of a stationary core  10 , a movable core  20 , an operating coil  30  and a shading coil  40 . Each of the stationary core  10  and the movable core  20  is an E-shaped core formed with approximately E-shaped flat rolled silicon steel sheets laminated and secured by rivets  19 . The E-shaped stationary core  10  has a central leg  11  and a pair of outside legs  12  arranged so that the central leg  11  is located between the pair of outside legs  12 , thereby forming the E-shape. The E-shaped movable core  20  has a central leg  21  and a pair of outside legs  22  arranged so that the central leg  21  is located between the pair of outside legs  22 , thereby forming the E-shape. The stationary core  10  and the movable core  20  are arranged so that a magnetic pole face  12   a  of the outside leg  12  at each end of the stationary core  10  and a magnetic pole face  22   a  of the outside leg  22  at each end of the movable core  20  face each other and are supported with relative movement between them. Therefore, it is possible that the magnetic pole faces  12   a  and  22   a  are made butted against each other and made separated from each other. The operating coil  30  is wound around the central leg  11  of the stationary core  10 . By turning on and off energization of the operating coil  30 , the movable core  20  is made butted against and separated from the stationary core  10 . 
         [0036]    As shown in  FIG. 1B , each of the outside legs  12  has a first groove  15  on its magnetic pole face  12   a  at a position on the side slightly near the central leg  11 . The first groove  15  is formed with the magnetic pole face  12   a  made dented almost perpendicularly thereto. The first groove  15  linearly extends in the direction of the thickness of the stationary core  10  (in the direction orthogonal to the paper in  FIG. 1B ). The cross-sectional shape of the first groove  15  viewed from its longitudinal direction is formed in approximately rectangular. Around the middle of each of the sidewalls of the first groove  15  in the direction of its depth, a groove  15   a  is formed into which a part of a first linear section  40   a  of the shading coil  40  is pressed. The shading coil  40  is subjected to plastic deformation by squeezing explained later. The groove  15   a  also extends in the direction of the thickness of the stationary core  10  in parallel with the first groove  15 . 
         [0037]    Each of the outside legs  12  has a second groove  17  formed on an outside face  12   b  at a position slightly below its upper end with the outside face  12   b  dented almost horizontally. Like in the first groove  1 , a part of a second linear section  40   b  forming the shading coil  40  is pressed into the second groove  17 . Here, likewise, the shading coil  40  is subjected to plastic deformation. The second groove  17  extends linearly in the direction of the thickness of the stationary core  10 . The first groove  15  and the second groove  17  are almost in parallel with each other. Moreover, the height of the bottom of the first groove  15  and the height of the lower face of the second groove  17  are almost equal. 
         [0038]    The stationary core  10  of the invention has no protrusion on the outside face  12   b  of each outside leg  12 , unlike the protrusion  113  provided on the stationary core  110  of the electromagnet device  101  in  FIGS. 5A and 5B . In the embodiment, the outside face  12   b  of each of the outside legs  12  is formed substantially flat except the second groove  17 . 
         [0039]    Furthermore, as shown in  FIG. 2 , the stationary core  10  has a through hole  10   a  formed so as to penetrate the stationary core  10  in its thickness direction. The through hole  10   a  is disposed at the end of the central leg  11  on the side opposite to the movable core  20 . Into the through hole  10   a , a supporting plate  91  is inserted. an elastic body  92  of an elastic material such as rubber is attached to the top end of the supporting plate  91  protruding from the through hole  10   a . Moreover, on the bottom surface of a frame (not shown) in which the stationary core  10  is contained, a cushion sheet  95  is laid. By the elastic body  92  and the cushion sheet  95 , the stationary core  10  is elastically supported on the frame in a so-called floating state. 
         [0040]    The shading coil  40  is integrally formed by stamping out an approximately ellipsoidal frame from a metal plate of aluminum base alloy, for example. The shading coil  40  has, as shown in  FIG. 2 , the first linear section  40   a  and the second linear section  40   b  almost in parallel with each other and semicircular sections  40   c  and  40   d  facing each other. 
         [0041]    According to a further embodiment shown in  FIG. 6 , a protrusion  17   b  is formed on a bottom  12   c  of the second groove  17 . In this embodiment, the shading coil  40  is more securely form-locked in the second groove  17  due to the protrusion  17   b.    
         [0042]    Next, an explanation will be made about an example of a method of attaching the shading coil  40  to each of the outside legs  12  of the stationary core  10 . 
         [0043]      FIGS. 3A to 3C  are views illustrating a method of attaching a shading coil to a magnetic pole. 
         [0044]    Here,  FIG. 3A  is a cross sectional view showing a dimensional relation between a shading coil and first and second grooves formed in an outside leg of a stationary core for attaching the shading coil thereto.  FIG. 3B  is a cross sectional view showing the step of pressing each of the first linear section of the shading coil inserted in the first grooves and the second linear section positioned on the side of the second groove by a squeezing tool.  FIG. 3C  is a cross sectional view showing a state in which the shading coil has been attached to the outside leg of the stationary core. 
         [0045]    As shown in  FIG. 3A , the first groove  15  is formed so that its width W 1  becomes substantially equal to the width W of each of the first linear section  40   a  and the second linear section  40   b  of the shading coil  40  except for a clearance provided for allowing the shading coil  40  to be inserted into the first groove  15 . Moreover, the first groove  15  is formed so that its depth D 1  becomes larger than the thickness T of each of the first linear section  40   a  and the second linear section  40   b . In addition, the second groove  17  is formed so that its width W 2  on the outside face  12   b  of the outside leg  12  is approximately equal to the thickness T of each of the first linear section  40   a  and the second linear section  40   b  but its width inside the outside leg  12  increases toward its bottom. Furthermore, the second groove  17  is formed so that its depth D 2  is made smaller than the width W of each of the linear section  40   a  and the second linear section  40   b.    
         [0046]    First, as shown in  FIG. 3B , the first linear section  40   a  of the shading coil  40  is inserted into the first groove  15  to make the second linear section  40   b  position on the side of the second groove  17 . Next to this, the first linear section  40   a  is pressed from above by a squeezing tool T 1  and the second linear section  40   b  is pressed from the side toward the second groove  17  by another squeezing tool T 2 . 
         [0047]    Then, as shown in  FIG. 3C , the first linear section  40   a  is made dented on its upper face by the squeezing tool T 1 , thereby being subjected to plastic deformation on its side faces so as to be pressed into the groove  15   a  on each of the sidewalls of the first groove  15 . This can prevent the shading coil  40  from coming off. Moreover, the second linear section  40   b  is pressed into the second groove  17 . Thus, its side face is made dented by the squeezing tool T 2 , and its end section inside the second groove  17  is subjected to plastic deformation upward and downward (upward and downward in the Figure) to be pressed into the inside of the second groove  17  in which the width of the second groove  17  is made widened toward the bottom. Each of the semicircular sections  40   c ,  40   d  of the shading coil  40  is deformed so as to extend outward (in the direction of the thickness of the core) from the outside leg  12  to the extent that the second linear section  40   b  is pressed into sideward. 
         [0048]    As explained in the foregoing, it is unnecessary for the stationary core  10  of the electromagnet device  1  according to the invention to provide a part irrelevant to a magnetic attractive force (the face  112   b  in  FIG. 5B ) on the outside leg  12 . Therefore, when the necessary magnetic attractive force of the stationary core  10  is equal to that of the related stationary core  110 , the stationary core  10  can be downsized as compared to the related stationary core  110  in which the protrusion  113  is provided for securing the shading coil  140 . Moreover, since the shading coil  40  inserted in both of the first groove  15  and second groove  17  is secured by squeezing, the shading coil  40  can be firmly attached to the stationary core  10  by relatively simple way. This makes the stationary core  10  excellent in productivity and durability. 
         [0049]    Following this, an electromagnetic contactor provided with such an electromagnet will be explained. 
         [0050]      FIG. 4  is a front view illustrating the structure of an electromagnetic contactor according to a second embodiment of the invention. 
         [0051]    The electromagnetic contactor  50 , as shown in  FIG. 4 , has a lower frame  60  and an upper frame  70  as a lower part and an upper part, respectively, of a case that is divided into two. Inside them, components such as the electromagnet device  1  and a contactor device  80  are provided. 
         [0052]    The electromagnet device  1  is what is explained with reference to  FIGS. 1A and 1B  and other drawings, and is formed of the stationary core  10 , the movable core  20 , the operating coil  30  and the shading coil  40 . The stationary core  10  is contained in the lower frame in a floating state. The stationary core  10  has a through hole formed so as to penetrate the stationary core  10  in its thickness direction. Into the through hole, the supporting plate  91  is inserted. The elastic body  92  of an elastic material such as rubber is attached to each end of the supporting plate  91  protruding from the through hole. The supporting plate  91  is secured to the lower frame  60  by the elastic body  92  and the stationary core  10  is elastically supported on the lower frame  50  in the floating state. 
         [0053]    The movable core  20  is contained in the upper frame  70  while facing the stationary core  10  so as to be made butted against and separated from the stationary core  10 . Between the movable core  20  and the operating coil  30 , a return spring  93  is provided. 
         [0054]    The contactor device  80  has a movable contactor  81  and a stationary contactor  82  which are butted against and separated from each other, thereby switching a circuit between connection and shutoff. The movable contactor  81  is held by a movable contact holder  83 . The movable contact holder  83  is supported by a connecting plate (not shown) on the back (upper face) of the movable core  20  so as to be slidable in the upper frame  70 . The movable contact holder  83  is held by a contact spring (not shown). The stationary contactor  82  is secured to the upper frame  70  at a part facing the movable contactor  81 . 
         [0055]    When the operating coil  30  is energized, the stationary core  10  and the movable core  20  attract each other, thereby moving the movable core  20  to contact the stationary core  10 . This makes the movable contact holder  83  supported by the movable core  20  move relative to the upper frame  70 . Therefore, the movable contactor  81  is made in contact with the stationary contactor  82 . With the operating coil  30  is de-energized, the movable core  20  is energized by the return spring  93  to be separated from the stationary core  10 . This makes the movable contactor  81  separated from the stationary core  82 . 
         [0056]    According to the electromagnetic contactor of the second embodiment explained in the foregoing, it becomes possible to downsize its core, and enhance its productivity and its durability as explained above. Thus, the electromagnetic contactor can be downsized and productivity and durability are enhanced. 
         [0057]    The disclosure of Japanese Patent Application No. 2008-158772 filed on Jun. 18, 2008 is incorporated as a reference. 
         [0058]    While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.