Patent Publication Number: US-9431200-B2

Title: Electromagnetic relay

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2014-0009919, filed on Jan. 27, 2014, the contents of which are all hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electromagnetic relay, more particularly to an electromagnetic relay which is capable of facilitating an assembling process and reducing a production cost. 
     2. Description of the Conventional Art 
     As is well known in the art, an electromagnetic relay is a device to open and close a main power supply side circuit and a load side circuit. 
       FIG. 1  is a sectional view illustrating an electromagnetic relay in accordance with a conventional art, and  FIG. 2  is an exploded view illustrating a main part of  FIG. 1 . 
     As shown in  FIGS. 1 and 2 , the conventional electromagnetic relay includes a contact part  10 , and a driving part  30  configured to open and close the contact part  10 . 
     The contact part  10  includes a housing  11 , a fixed contact  15  fixedly disposed at the housing  11 , and a movable contact  21  configured to be in contact with or separated from the fixed contact  15 . 
     The driving part  30  includes a coil  41 , a yoke  51  disposed around the coil  41  to form a magnetic path, a fixed core  61  disposed within the coil  41 , a movable core  71  disposed to be close to or be separated from the fixed core  61 , a shaft  81  having one end connected to the movable core  71  and another end connected to the movable contact  21 , and a restoration spring  91  configured to restore the movable core  71  to an initial position. 
     The coil  41  includes a bobbin  45 . 
     The fixed core  61  is inserted into the bobbin  45 . 
     The fixed core  61  is connected to the yoke  51  to form a magnetic path. 
     The shaft  81  is inserted into the fixed core  61  so as to be relatively movable with respect to the fixed core  61 . 
     The movable contact  21  is connected to one end of the shaft  81  so as to be relatively movable with respect to the shaft  81 . 
     A compression spring  25 , configured to apply pressure against the movable contact  21  to elastically contact with the fixed contact  15 , is provided at an end of the shaft  81 . An insertion portion  73  is provided in the movable core  71  so that an end of the shaft  81  may be inserted therein. 
     The shaft  81  is made of metal. 
     The movable core  71  and the shaft  81  are integrally coupled to each other by welding. 
     However, in such a conventional electromagnetic relay, when the movable core  71  and the shaft  81  are coupled to each other by welding, a lot of time and effort are required. 
     Further, it is difficult to identify whether the welding part has any defect or not by the naked eye, after the shaft  81  and the movable core  71  have been welded to each other. 
     Further, an additional device (for example, a jig for adjusting a stroke) is required to maintain a stroke between the fixed core  61  and the movable core  71  as a predetermined gap, thereby increasing a working time and requiring additional facilities. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an electromagnetic relay which is capable of facilitating an assembling process and reducing a production cost. 
     Another object of the present invention is to provide an electromagnetic relay which is capable of facilitating an assembling process by eliminating a welding process when coupling the shaft and the movable core. 
     A further object of the present invention is to provide an electromagnetic relay which is capable of reducing additional facilities and production cost when coupling the shaft and the movable core. 
     To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided an electromagnetic relay, including a housing; a fixed contact provided within the housing; a movable contact movable to contact or be separated from the fixed contact; and a driving unit configured to drive the movable contact to be in contact with or separated from the fixed contact, wherein the driving unit comprises a coil; a yoke disposed within the coil and having an inner section for forming a magnetic path inside and outside of the coil; a movable core disposed within the coil to be attractable by the inner section; and a shaft having one end connected to the movable core and another end connected to the movable contact. 
     The shaft may include a shaft body and a coupling portion provided at an end of the shaft body and coupled with the movable core. 
     The electromagnetic relay may further include a fixing member coupled to an end of the coupling portion which is exposed to outside of the movable core and configured to restrict separation of the coupling portion from the movable core. 
     The electromagnetic relay may further include a hook provided at an end of the coupling portion and a hook locking jaw engaged with the hook in an axial direction provided at the fixing member. 
     The coupling portion may include a first diameter section extended from an end of the shaft body, a second diameter section formed at one side of the first diameter section and having a smaller diameter than the first diameter section, and a hook locking jaw accommodating portion formed at one side of the second diameter section, and configured to accommodate therein the hook locking jaw. 
     The hook locking jaw may be configured to be elastically transformed when the hook is coupled thereto. 
     The fixing member may include a cylindrical fixing member body, and wherein the hook locking jaw may be provided in plurality in number and disposed within the fixing member body in a circumferential direction. 
     Each of the shaft and the movable core may include an engaging portion to restrict an exposed range of the hook. 
     The engaging portion may include a hooking portion provided at the shaft, and a hooking jaw provided at the movable core and configured to be engaged with the hooking part in an axial direction. 
     The hook locking jaw may include a hook accommodating portion to accommodate therein the hook. 
     The fixing member body may include a through hole for communicating with the hook accommodating portion. 
     The movable core may include a fixing member insertion portion configured to insert the fixing member therein. 
     The fixing member body may include a flange extended outward in a radius direction. 
     The shaft may be made of a synthetic resin material. 
     The movable contact and the shaft may be connected to each other so as to be relatively movable with each other, and the shaft may include a compression spring applying an elastic force to the movable contact for elastic contact with the fixed contact, and the shaft may include a compression spring support portion for supporting the compression spring. 
     The shaft may include a space portion formed by cutting out or removing part of the shaft. 
     The yoke may include a first yoke disposed outside the coil to form a magnetic path and a second yoke including a connection section configured to connect the inner section to the first yoke. 
     A restoration spring may be provided between the inner section of the second core and the movable core so as to return the movable core to its initial position, and the inner section may include a restoration spring support portion for supporting an end of the restoration spring. 
     The inner section may include a cylindrical portion having a receiving space therein and a shielding portion for shielding an end of the cylindrical portion, and the restoration spring support portion may be formed on the shielding portion in a concaved manner. 
     The first yoke may be formed in a U-shape, and may include a shielding portion disposed on an end of the coil in an axial direction, and side wall portions bent from two ends of the shielding portion and disposed at an outer circumferential surface of the coil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments and together with the description serve to explain the principles of the invention. 
       In the drawings: 
         FIG. 1  is a sectional view illustrating an electromagnetic relay in accordance with the conventional art; 
         FIG. 2  is an enlarged view of a main part of the electromagnetic relay in accordance with the conventional art; 
         FIG. 3  is a sectional view illustrating an electromagnetic relay in accordance with an embodiment of the present invention; 
         FIG. 4  is an enlarged view illustrating a yoke of  FIG. 3 ; 
         FIG. 5  is a perspective view illustrating a shaft, a second yoke, a movable core, and a fixing member of  FIG. 3  in an unassembled state; 
         FIG. 6  is an enlarged view illustrating the movable contact and the shaft of  FIG. 3 ; 
         FIG. 7  is an enlarged view illustrating the movable core of  FIG. 3 ; 
         FIG. 8  is an enlarged view illustrating the movable core and the fixing member of  FIG. 3  in an assembled state; and 
         FIG. 9  is an enlarged view illustrating the fixing member of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, a preferred embodiment of an electromagnetic relay according to the present invention will now be described in detail with reference to the accompanying drawings. 
     As shown in  FIG. 3 , an electromagnetic relay according to an embodiment of the present invention comprises a fixed contact  111 , a movable contact  121  disposed to be contactable to the fixed contact  111 , and a driving unit  130  configured to drive the movable contact  121  to contact or be separated from the fixed contact  111 . 
     The driving unit  130  includes a coil  141 , a yoke  150  disposed within the coil  141  and having an inner section  162  to form a magnetic path therein, the yoke  150  forming a magnetic path inside and outside of the coil  141 , a movable core  180  disposed within the coil  141  to be attractable through the inner section  162 , and a shaft  190  having one end connected to the movable core  180  and another end coupled to the movable contact  121 . 
     The electromagnetic relay may include a housing  110  having an accommodating space therein. 
     The fixed contact  111  may be fixed to the housing  110 . 
     The movable contact  121 , which is movable to contact or be separated from the fixed contact  111 , may be provided within the housing  110 . 
     The movable contact  121  may be configured as a pair of movable contacts which are spaced apart from each other. 
     The movable contact  121  may include a connection portion  123  made of an electrically conductive material. 
     The connection portion  123  may include a through hole  125  through by which the shaft  190  is coupled in a relative movable manner. 
     The driving unit  130 , configured to drive the movable contact  121  to contact or be separated from the fixed contact  111 , may be provided at one side of the movable contact  121 . 
     The driving unit  130  may be provided at a lower side of the housing  110 . 
     The driving unit  130  may include a coil  141  to form a magnetic path when a power is applied thereto. 
     The coil  141  may be provided in a cylindrical shape. 
     The coil  141  may include a bobbin  145 . 
     The bobbin  145  may be provided in a cylindrical shape. 
     The yoke  150  may be provided around the coil  141  to form a magnetic path. 
     The yoke  150  may include a first yoke  151  disposed outside the coil  141  to form a magnetic path, and a second yoke  161  having an inner section  162  disposed within the coil  141  to form a magnetic path and a connection section  170  connecting the inner section  162  to the first yoke  151 . 
     As shown in  FIG. 4 , the first yoke  151  may have a U-shaped section. 
     The first yoke  151  may include a shielding portion  153  disposed at an end of the coil  141 , and a side wall portion  155  bent from two ends of the shielding portion  153  and disposed at an outer circumferential surface of the coil  141 . 
     A movable core guiding portion  154 , configured to guide the movable core  180  disposed in the shielding portion  153 , may be provided in the shielding portion  153 . 
     The movable core guiding portion  154  may be formed to have a shape corresponding to an external shape of the movable core  180 , and may guide the movable core  180  and form a magnetic path together with the movable core  180 . 
     The movable core guiding portion  154  may be provided in a cylindrical shape. 
     The inner section  162  may be provided in a hollow cylindrical shape. 
     The inner section  162  may include a cylindrical portion  164 , and a shielding portion  166  to shield one end of the cylindrical portion  164 . 
     A through hole  167  may be provided at the inner section  162  such that the shaft  190  is relative-movably inserted into the inner section  162  there through. 
     The through hole  167  may be provided to penetrate the shielding portion  166 . 
     The connection section  170  may be provided at an end portion of the cylindrical portion  164  to extend in a radius direction. 
     The connection section  170  may be provided in a rectangular plate shape. 
     The connection section  170  may include an opening portion at a central part thereof. 
     The inner section  162  may be provided at one side of the opening portion of the connection section  170 . 
     The opening portion of the connection section  170  may be formed to communicate with the inner section  162 . Thus, the shaft  190  may be inserted into the inner section  162  through the opening portion. 
     Meanwhile, the housing  110  may be configured to have an open side. 
     More specifically, the housing  110  may be configured to be open toward the driving unit  130 . 
     The second yoke  161  may be disposed at the opening portion of the housing  110 . 
     The connection section  170  may be disposed at the opening portion of the housing  110 . 
     The opening portion of the housing  110  may be closed by the second yoke  161 , and thus discharge of an arc generated between the fixed contact  111  and the movable contact  121  can be prevented. 
     The side wall portion  155  of the first yoke  151  may be connected to the connection section  170  of the second yoke  161 . Thus, the second yoke  161  and the first yoke  151  may be magnetically connected to each other. Under such a configuration, a magnetic line is generated by the coil  141  when a power is applied to the coil  141 , and may flow through the first yoke  151 , the second yoke  161 , and the movable core  180 , sequentially. In such a state, the movable core  180  may be moved toward the second yoke  161  by a magnetic attractive force of the inner section  162  of the second yoke  161 . 
     The movable core  180  may be made of a magnetic material. 
     The movable core  180  may be formed in a circular bar shape. 
     The shaft  190  may be connected to the movable core  180 . 
     The shaft  190  and the movable core  180  may be coupled to each other by an assembling method, to thereby omit a welding process so that a prompt and easy coupling work can be performed. 
     As shown in  FIGS. 5 and 6 , for example, one end of the shaft  190  may be coupled to the movable core  180  and the other end of the shaft  190  may be coupled to the movable contact  121 . 
     The shaft  190  may be made of, for example, a synthetic material. Thus, the weight of the shaft  190  can be remarkably reduced, when compared to the conventional shaft which is made of metal for welding. Further, a moving speed of the movable contact  121  can be relatively increased, when compared to the conventional one in a case where the same magnetic force is formed. 
     The shaft  190  may include a shaft body  191 , a movable contact coupling portion  201  formed at one end of the shaft body  191  and to which the movable contact  121  is coupled, and a coupling portion  211  formed at another end of the shaft body  191  and to which the movable core  180  is coupled. 
     The shaft body  191  may be configured to have a relatively large diameter. 
     The shaft body  191  may be configured in a circular rod shape so as to be movable with respect to the inner surface of the inner section  162 . 
     A space portion  193  may be formed at the shaft body  191  by cutting-out or removing part of the shaft body  191  so that a weight of the shaft body  191  can be reduced. In this embodiment of the present invention, although the space portion  193  is formed to penetrate through the shaft body  191 , the space portion  193  may be configured on an outer surface of the shaft body  191  in the form of a recess concaved by a predetermined depth. 
     The movable contact coupling portion  201  may be configured to have a smaller outer diameter than the shaft body  191 . 
     The movable contact coupling portion  201  may be coupled to the connection portion  123  of the movable contact  121  to be relatively movable with respect thereto. 
     As shown in  FIG. 7 , the movable contact coupling portion  201  may be disposed to be in contact with an outer surface of the movable contact  121  and include a movable contact support portion  202 . 
     A compression spring  205  may be provided around the movable contact coupling portion  201 . 
     One end of the compression spring  205  may be in contact with the movable contact  121  and the other end thereof may be in contact with the shaft body  191 . Under such a configuration, when the shaft body  191  is moved toward a contact position, the compression spring  205  pressed by the shaft body  191  is compressed and, thereby the movable contact  121  may be elastically compressed. Thus, the movable contact  121  may be maintained in a contact state with a predetermined compression force. 
     A compression spring support portion  195  may be provided at the shaft  190  to support the compression spring  205 . 
     The compression spring support portion  195  may have a larger outer diameter than the compression spring  205 . 
     The compression spring support portion  195  may be formed at an end of the shaft body  191 . The compression spring support portion  195  is formed to have a planar surface in this embodiment. However, the compression spring support portion  195  may be configured as a recess in which an end of the compression spring  205  is inserted or a protrusion which is inserted into the compression spring  205 . Between the compression spring  205  and the compression spring support portion  195 , a washer (not shown) may be provided. 
     In this embodiment of the present invention, the compression spring support portion  195  has an outer diameter larger than that of the shaft body  191  to extend outward in a radius direction of the shaft body  191 . However, the compression spring support portion  195  may be formed to have the same diameter as that of the shaft body  191 . 
     The coupling portion  211  may have a smaller outer diameter than the shaft body  191 . 
     The coupling portion  211  may be formed to penetrate through the movable core  180 . 
     One end of the coupling portion  211  may be exposed outward through the movable core  180 . 
     A fixing member  230  may be provided at the exposed end of the coupling portion  211  in order to prevent the coupling portion  211  from being separated from the movable core  180 . 
     As shown in  FIG. 7 , an insertion portion  183  may be provided at an end of the movable core  180 , so that the coupling portion  211  may be inserted there through. 
     A fixing member insertion portion  185  may be provided at an end of the movable core  180 , so that the fixing member  230  may be inserted and coupled there through. Under such a configuration, an axial length of the shaft  190  can be reduced and thus, the size of the electromagnetic relay can be minimized. Further, since the axial length of the movable core  180  may be increased, the shaft  190  and the movable core  180  coupled to each other can be stably operated. 
     The fixing member insertion portion  185  may be formed at an end (a lower end in the drawing) of the movable core  180 . The fixing member insertion portion  185  may be formed to have a depth large enough for a lower end of the movable core  180  and a lower end of the fixing member  230  to be on the same plane when the fixing member  230  is inserted therein. 
     A yoke contact portion  186  may be provided on an external surface of the movable core  180 . 
     The movable core  180  may be provided with an extension portion  187  in a radius direction to extend its surface area in correspondence to the inner section  162 . 
     Between the movable core  180  and the inner section  162 , a restoration spring  225  may be provided to return the movable core  180  to its initial position. 
     The initial position means a position where the movable contact  121  is separated from the fixed contact  111  for insulation. 
     The restoration spring  225  may be coupled around the coupling portion  211 . 
     A restoration spring accommodating portion  181  may be provided at the movable core  180  to accommodate one end (a lower end in the drawing) of the restoration spring  225  therein. 
     A restoration spring support portion  168  may be provided at an end of the inner section  162  of the second yoke  161  to support the other end (an upper end in the drawing) of the restoration spring  225 . 
     The restoration spring support portion  168  may be formed in a concave manner at the shielding portion  166  of the inner section  162 . 
     A hook  215  may be provided at an end of the coupling portion  211 . 
     The hook  215  may be formed to be exposed outwardly through a lower end of the movable core  180 . 
     An engaging portion  220  may be provided at a predetermined portion of the shaft  190  and the movable core  180  to restrict an insertion depth of the coupling portion  211  of the shaft  190 . 
     The engaging portion  220  may restrict an exposed range of the hook  215  by being engaged with each other in an axial direction of the shaft  190 . 
     The engaging portion  220  may include a hooking portion  222  formed in a stepped manner in a radius direction of the coupling portion  211 , and a hooking jaw  224  which contacts the movable core  180  in an axial direction of the hooking portion  222  to restrict insertion of the hooking portion  222 . 
     More specifically, the coupling portion  211  of the shaft  190  may include a first diameter section  212 , a second diameter section  213  having a smaller diameter than the first diameter section  212 , and a hooking portion  222  formed at an interface between the first diameter section  212  and the second diameter section  213 . 
     The insertion portion  183  may have a smaller diameter than the restoration spring accommodating portion  181 . 
     The insertion portion  183  of the movable core  180  may have an inner diameter corresponding to the second diameter section  213  of the coupling portion  211  of the shaft  190 . 
     A hooking jaw  224  may be formed at an interface between the restoration spring accommodating portion  181  and the insertion portion  183 . 
     The fixing member  230  may include a hook locking jaw  235  engaged with the hook  215 . 
     As shown in  FIGS. 8 and 9 , the fixing member  230  may include a cylindrical fixing member body  231 , and a plurality of hook locking jaws  235  disposed within the fixing member body  231  in a circumferential direction. 
     The fixing member body  231  may have a through hole  240  at a center thereof. 
     The fixing member body  231  may include a flange  233  extended in a radius direction. 
     The hook locking jaw  235  may be provided in plurality in number. 
     The hook locking jaw  235  may be provided, for example, in four. 
     The hook locking jaw  235  may be formed to protrude inward along a radius direction to be engaged with the hook  215  in an axial direction. 
     The hook locking jaw  235  may be elastically transformed when engaged with the hook  215 . 
     As shown in  FIG. 9 , the hook locking jaw  235  may have a predetermined gap ‘D’ from the fixing member body  231  to avoid any interference with an inner surface of the fixing member body  231 , in a case where the hook locking jaw  235  is elastically transformed outward when engaged with the hook  215 . 
     More specifically, the hook locking jaw  235  may include a hook locking jaw body  236  which is formed at an inner side of the fixing member body  231  in an axial direction, and a hooking jaw portion  237  formed at an end portion of the hook locking jaw body  236  to protrude inward in a radius direction. 
     Each of the hook locking jaws  235  may include an inclined surface  238 . 
     The inclined surface  238  may be formed to be inclined outward with respect to the hooking jaw portion  237 . 
     Thus, the hook locking jaw  235  may smoothly contact the inclined surface  238  when coupled with the hook  215 . 
     The hooking jaw portion  237  may be in surface-contact with the end of the hook  215  in an axial direction to restrict a relative movement, thereby preventing the hook  215  from being separated from the hook locking jaws  235 . 
     A hook accommodating portion  239  may be provided at an inner side of the hook locking jaws  235  to accommodate therein the hook  215 . 
     The hook accommodating portion  239  may be configured to communicate with outside through the through hole  240 . 
     A hook locking jaw accommodating portion  214 , configured to accommodate part of the hook locking jaw  235  therein, may be provided at one side of the second diameter section  213 . 
     More specifically, the hook locking jaw accommodating portion  214  may be configured to accommodate therein an end portion of the hooking jaw portion  237  of the hook locking jaw  235 , as shown in  FIGS. 7 and 8 . 
     The hook locking jaw accommodating portion  214  may be provided between the hook  215  and the second diameter section  213 . 
     Under such a configuration, the shaft  190  may be inserted into the inner section  162  of the second yoke  161  through the opening portion. 
     The restoration spring  225  may be provided around the inner section  162  of the second yoke  161 . 
     When the shaft body  191  is inserted into the inner section  162  of the second yoke  161 , the coupling portion  211  of the shaft body  191  may protrude to outside of the inner section  162  by passing through the through hole  167 . 
     The end of the coupling portion  211  of the shaft body  191 , which has passed through the inner section  162 , may be inserted into the restoration spring  225 . 
     Upon continuous insertion of the shaft  190 , the coupling portion  211  of the shaft  190  may be inserted into the insertion portion  183  of the movable core  180 . 
     Once the shaft  190  is continuously inserted into the inner section  162 , the hooking portion  222  contacts the hooking jaw  224 , and thus the movement of the shaft  190  may be restricted. 
     At this moment, the hook  215  may protrude toward the fixing member insertion portion  185  after having passed through the insertion portion  183 . 
     The fixing member  230  may be fixed to the hook  215 . 
     More specifically, when inserting the fixing member  230  into the fixing member insertion portion  185  of the movable core  180 , each hook locking jaw  235  of the fixing member  230  is compressed by the inclined surface  217  of the hook  215  and then elastically transformed to be outward widened in a radius direction. 
     In this embodiment, the fixing member  230  is inserted into the movable core  180  after the shaft  190  has been inserted into the movable core  180 , as an example. However, the fixing member  230  may be firstly inserted into the movable core  180 , and then the shaft  190  may be inserted into the movable core  180 . 
     Upon completion of the insertion of the fixing member  230 , each hook locking jaw  235  of the fixing member  230  returns to its initial position by its elasticity so that an end of the hook  215  and the hooking jaw portion  237  of the hook locking jaw  235  become surface-contact with each other, thereby restricting separation of the shaft  190  from the movable core  180 . 
     The restoration spring  225  may apply an elastic force to the movable core  180  to separate the movable core  180  from the inner section  162  of the second yoke  161 , by the elastic force accumulated while the restoration spring  225  is compressed when the shaft  190  is coupled with the movable core  180 . 
     As described above, according to an embodiment of the present invention, as the shaft and the movable core may be coupled to each other in a simple assembling manner, an assembling process can be facilitated and the production cost can be reduced. 
     Further, the shaft and the movable core can be rapidly and easily coupled to each other by eliminating a welding process. 
     Further, the shaft and the movable core can be rapidly and easily coupled to each other by providing the hook at an end of the shaft and the fixing member at an end of the moving core for engagement with each other. 
     Further, since the engaging portions are provided at the shaft and the movable core, additional equipment for maintaining a stroke between the fixed core and the movable core when coupling the shaft to the movable core is not required so that the production cost can be reduced. 
     Further, the weight of the electromagnetic relay can be reduced by eliminating the use of a circular rod shaped fixed core and by providing the shaft formed of a synthetic resin material. 
     As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.