Abstract:
A electromagnetic relay including a plate-shaped pivoting piece ( 32 ), one end of which is supported in cantilever state, pivoted by a movable block ( 40 ), which reciprocates in the up-down direction on the basis of excitation and demagnetization of an electromagnet block ( 20 ) housed within a housing ( 10, 50 ), and causes a movable contact ( 34 ) formed on the other end of the plate-shaped pivoting piece ( 32 ) to make/break contact with an anchored contact ( 36 ) formed on the tip section of an anchored contact terminal ( 35 ). In particular, the one-end section of the plate-shaped pivoting piece ( 32 ) is supported pivotably in cantilever state by the upper end section of a movable contact terminal ( 31 ), with a support spring ( 33 ) comprising a conductive sheet spring material interposed therebetween.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims benefit of priority to Japanese Patent Application No. 2010-271826, filed on Dec. 6, 2010 of which full contents are added by herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an electromagnetic relay, and particularly to an electromagnetic relay capable of passing a large capacity of current. 
         [0003]    Conventionally, as an electromagnetic relay capable of passing a large capacity of current, for example, as shown in FIG. 8 of U.S. Pat. No. 7,710,224 A, there has been an electromagnetic relay provided with a contact button at a tip portion of a triumvirate spring assembly constructed by superimposing three sheet springs in order to reduce electric resistance. The contact button is caused to make and break contact with a contact button to perform electrification. 
         [0004]    However, in the foregoing electromagnetic relay, since the triumvirate spring assembly is constructed by superimposing the three conductive sheet springs, not only a number of parts and a number of assembly processes are large but also variation in operating characteristics is easily caused by accumulation of assembling errors. 
         [0005]    Moreover, the triumvirate spring assembly needs to fulfill two functions of elastic supporting and electrification. Therefore, for example, if a cross-sectional area of each of the conductive sheet springs is increased to enhance the electrification characteristics, spring loading becomes larger, which requires larger driving energy for driving, so that the enhancement of the electrification performance is disadvantageously limited. 
         [0006]    Hence, an object of the present invention is to provide an electromagnetic relay having excellent electrification characteristics, wherein a number of parts and a number of assembling processes are smaller, and variation in operating characteristics does not tend to be caused. 
       SUMMARY OF THE INVENTION 
       [0007]    According to the present invention, an electromagnetic relay in which a plate-shaped pivoting piece supported in a cantilever state at one end portion and pivoted by a movable block, the plate-shaped pivoting piece is adapted to reciprocate in an up-down direction on the basis of excitation and demagnetization of an electromagnet block housed within a housing, and to thereby cause a movable contact provided at another end portion of the plate-shaped pivoting piece to make and break contact with an anchored contact provided at a tip portion of an anchored contact terminal. At an upper end portion of a movable contact terminal, the one end portion of the plate-shaped pivoting piece is pivotably supported in the cantilever state with a support spring interposed therebetween, the support spring being made of a conductive sheet spring material. 
         [0008]    According to the present invention, since a circuit can be opened and closed by means of the one plate-shaped pivoting piece, there can be obtained an electromagnetic relay in which the number of parts and the number of assembly processes are smaller and variation in operating characteristics is smaller than those of the conventional example. 
         [0009]    Moreover, since the function of the plate-shaped pivoting piece is only electrification, a cross-sectional area can be made larger without considering spring loading, so that the electromagnetic relay having excellent electrification characteristics can be obtained. 
         [0010]    In an embodiment of the electromagnetic relay, another end portion of the support spring may be extended up to the other end portion of the plate-shaped pivoting piece, and the movable contact may be caulking-fixed to the other end portion of the plate-shaped pivoting piece and the other end portion of the support spring to be integrated. 
         [0011]    According to the present embodiment, since the movable contact is caulking-fixed to the other end portion of the plate-shaped pivoting piece and the other end portion of the support spring to be integrated, electric resistance becomes smaller, so that the electromagnetic relay having high energy efficiency can be obtained. 
         [0012]    In another embodiment of the present invention, an elastic tongue piece cut and raised from the support spring is sandwiched by a cut-out portion for engagement of the movable block to operably sustain the plate-shaped pivoting piece by the movable block. 
         [0013]    According to the present embodiment, since the plate-shaped pivoting piece is sustained by the movable block by means of the elastic tongue piece of the support spring, the electromagnetic relay having favorable operating characteristics without rattle can be obtained. 
         [0014]    In yet another embodiment of the present invention, a bent narrow portion of the support spring is engaged with an engagement receiving portion provided at the one end portion of the plate-shaped pivoting piece. 
         [0015]    According to the present embodiment, engaging the engagement receiving portion of the plate-shaped pivoting piece with the bent narrow portion of the support spring prevents the plate-shaped pivoting piece from being displaced horizontally, so that the electromagnetic relay having stable operating characteristics can be obtained. 
         [0016]    In a different embodiment of the present invention, one end portion of the support spring is extended up to a lower end portion of the movable contact terminal projected from the housing. 
         [0017]    According to the present embodiment, the electromagnetic relay having not only smaller electric resistance but also favorable heat dissipation through the support spring can be obtained. 
         [0018]    In another embodiment of the present invention, the upper end portion of the movable contact terminal is folded on a side of the anchored contact terminal, by which the one end portion of the plate-shaped pivoting piece is brought into linear contact with the upper end portion of the movable contact terminal. 
         [0019]    According to the present embodiment, since the one end portion of the plate-shaped pivoting piece makes linear contact with an edge portion of the upper end portion of the movable contact terminal, the smooth operating characteristics can be obtained. Particularly, even if the edge portion of the upper end portion of the movable contact terminal is worn away, the upper end portion is inclined, thus bringing about a so-called shaving effect. Thus, a pivoting fulcrum of the plate-shaped pivoting piece does not tend to be displaced, so that stable operating characteristics can be assured over a long period. 
         [0020]    In yet another embodiment of the present invention, insulating walls that partition the electromagnet block and the plate-shaped pivoting piece are projected laterally in both side surfaces of the movable block, respectively. 
         [0021]    According to the present embodiment, projecting the insulation walls in the movable block makes an insulation distance longer, thereby bringing about an effect that the electromagnetic relay having favorable insulation characteristics can be obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIGS. 1A and 1B  are perspective views showing one embodiment of an electromagnetic relay according to the present invention. 
           [0023]      FIG. 2  is an exploded perspective view of the electromagnetic relay shown in  FIGS. 1A and 1B . 
           [0024]      FIG. 3  is a substantial-part enlarged perspective view of the exploded perspective view shown in  FIG. 2 . 
           [0025]      FIG. 4  is an exploded perspective view of the electromagnetic relay shown in  FIGS. 1A and 1B  seen from a different angle. 
           [0026]      FIG. 5  is a substantial-part enlarged perspective view of the exploded perspective view shown in  FIG. 4 . 
           [0027]      FIGS. 6A and 6B  are perspective views showing a contact mechanism shown in  FIGS. 1A and 1B . 
           [0028]      FIGS. 7A ,  7 B,  7 C, and  7 D are a front view, a right side view, a cross-sectional view along C-C of  FIG. 7A , and a cross-sectional view along D-D in  FIG. 7B , respectively. 
           [0029]      FIGS. 8A ,  8 B are front cross-sectional views showing states before and after operation of the electromagnetic relay shown in  FIGS. 1A and 1B . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    An embodiment of an electromagnetic relay according to the present invention will be described in accordance with the accompanying drawings of  FIGS. 1A to 8B , wherein references will be made to the figures interchangeably while discussing the electromagnetic relay. 
         [0031]    As shown in  FIG. 2 , the present embodiment is applied to a self-sustaining electromagnetic relay, which is made up of a substantially box-shaped base  10 , an electromagnet block  20  incorporated in the base  10 , a contact mechanism portion  30 , a movable block  40 , and a substantially box-shaped cover  50  fitting on the base  10  to form an enclosed space. 
         [0032]    As shown in  FIG. 2 , in the base  10 , a slit for guide  12  is formed between paired partition walls  11   a ,  11   b , which are projected on the same horizontal plane so as to vertically partition inner surfaces thereof. Moreover, in the base  10 , a vertical guide groove  13  communicating with the slit for guide  12  is formed in the inner side surface, and a vertical guide recessed portion  14  is provided immediately under the slit for guide  12 . Further, in the base  10 , first and second projected portions for positioning  15 ,  16  are projected in portions located above the partition walls  11   a ,  11   b  in the inner surface, respectively. Furthermore, in the base  10 , slits for press-fitting  17   a,    17   b  are provided at lower corner portions, respectively, and locking protrusions  18  are provided in an outer circumferential surface thereof. 
         [0033]    In the electromagnet block  20 , a coil  23  is wound around a spool  22  having flange portions  21   a,    21   b  on both sides, and three coil terminals  24   a,    24   b,    24   c  are insert-molded in the flange portion  21   b  of the spool  22 . Substantially J-shaped first, second iron cores  25 ,  26 , and a third iron core  27  are inserted from both sides into a through-hole  21   c  ( FIG. 5 ) provided in the spool  22 , respectively ( FIG. 3 ) to thereby sandwich an iron core portion  27   a  ( FIG. 3 ) of the third iron core  27  between iron core portions  25   a,    26   a  ( FIG. 3 ) of the first and second iron cores  25 ,  26 . 
         [0034]    As shown in  FIG. 3 , the contact mechanism portion  30  is made up of a movable contact terminal  31  with an upper end portion  31  a thereof folded inward, a plate-shaped pivoting piece  32  with one end portion thereof placed on the upper end portion  31   a  of the movable contact terminal  31 , a support spring  33  made of a conductive sheet spring material and fixed to outer circumferential surfaces of the movable contact terminal  31  and the plate-shaped pivoting piece  32  to pivotably support the plate-shaped pivoting piece  32 , a movable contact  34  caulking-fixed to a free end portion of the plate-shaped pivoting piece  32  and a free end portion of the support spring  33 , and an anchored contact terminal  35  with an anchored contact  36  caulking-fixed to a bent horizontal portion  35   a.  The movable contact  34  is arranged so as to be able to make/break contact with the anchored contact  36 . 
         [0035]    Particularly, the support spring  33  is caulking-fixed along the outer circumferential surfaces of the movable contact terminal  31  and the plate-shaped pivoting piece  32 , and the movable contact  34  is caulking-fixed to the free end portion of the plate-shaped pivoting piece  32 , thereby being integrated with the plate-shaped pivoting piece  32 . Moreover, in the support spring  33 , in the vicinity of the movable contact  34 , three elastic tongue pieces  33   a,    33   b,    33   c  cut and raised in a zigzag shape, and a bent narrow portion  33   d  are provided. Thus, there is an advantage that horizontal displacement of the plate-shaped pivoting piece  32  can be prevented by engaging the narrow portion  33   d  of the support spring  33  with an engagement receiving portion  32   a  provided at the one end portion of the plate-shaped pivoting piece  32 . 
         [0036]    As shown in  FIG. 7 , in the movable block  40 , paired first and second movable iron pieces  43 ,  44  sandwiching a permanent magnet  42  vertically are insert-molded in a block body  41 , by which both end portions of the first and second movable iron pieces  43 ,  44  are projected laterally. Moreover, in the block body  41 , a cut-out portion  45  to be engaged with the plate-shaped pivoting piece  32  ( FIG. 3 .) is provided. Furthermore, protrusions for guide  46  are provided in end surfaces on both sides of the block body  41 , respectively, and insulating walls  47  are projected laterally in side surfaces on both sides on the same horizontal plane, respectively. 
         [0037]    As shown in  FIG. 4 , the cover  50  has a front shape finable in the base  10 , and is provided with a vertical guide groove  51  at a position corresponding to the vertical guide groove  13  ( FIG. 2 .) of the base  10  and with locking holes  52  in outer circumferential surfaces. 
         [0038]    When the foregoing components are assembled, the iron core portions  25   a ,  26   a  of the first and second iron cores  25 ,  26  and the iron core portion  27   a  of the third iron core  27  are inserted from both the sides of the through-hole  21   c  of the spool  22  with the coil  23  wound, respectively. The iron core portion  27   a  of the third iron core  27  is sandwiched between the iron core portions  25   a,    26   a  of the first and second iron cores  25 ,  26  to construct the electromagnet block  20 . Subsequently, assembling the electromagnet block  20  into the base  10  allows the first projected portion for positioning  15  of the base  10  to position magnetic pole portions  25   b,    26   b  of the first and second iron cores  25 ,  26 , and the second projected portion for positioning  16  to position a magnetic pole portion  27   b  of the third iron core  27 . 
         [0039]    Moreover, the anchored contact terminal  35  is press-fitted in the slit for press-fitting  17   b  of the base  10 , and the movable contact terminal  31 , which pivotably supports the plate-shaped pivoting piece  32  with the support spring  33  interposed, is press-fitted in the slit for press-fitting  17   a  of the base  10 , by which the movable contact  34  is opposed to the anchored contact  36  so as to be able to make/break contact with each other. 
         [0040]    The block body  41  of the movable block  40  is fitted in the slit for guide  12  ( FIG. 2 ) of the base  10 , which allows the first and second movable iron pieces  43 ,  44  to be arranged between the first and second magnetic pole portions  25   b,    26   b , and the third magnetic pole portion  27   b  to be arranged between the first and second movable iron pieces  43 ,  44 . Furthermore, the cut-out portion  45  of the block body  41  is fitted to the elastic tongue pieces  33   a,    33   b,    33   c  ( FIG. 3 .) cut and raised, which enables the plate-shape pivoting piece  32  to be sustained without rattle in the movable block  40 . At this time, the insulating walls  47  are located immediately under the slit for guide  12  ( FIG. 12 .), which makes an insulation distance longer; so that the electromagnetic relay having high insulation characteristics can be obtained. 
         [0041]    Finally, the cover  50  is positioned to the base  10 , and the locking protrusions  18  of the base  10  are locked in the locking holes  52  of the cover  50 , when the assembling work is completed. 
         [0042]    Next, operation of the electromagnetic relay having the above configuration will be described. 
         [0043]    As shown in  FIG. 8A , before a voltage is applied to the coil  23  of the electromagnet block  20 , the first movable iron piece  43  is attached to the first magnetic pole portion  25   b  by a magnetic force of the permanent magnet  42 , and the second movable iron piece  44  is attached to the third magnetic pole portion  27   b  to close a magnetic circuit. Thus, the movable block  40  lifts a tip portion of the plate-shaped pivoting piece  32  upward against a spring force of the support spring  33 , so that the movable contact  34  is in a state breaking contact with the anchored contact  36 . 
         [0044]    When the voltage is applied to the coil  23  in a direction where a magnetic flux of the permanent magnet  42  is cancelled, the first and second movable iron pieces  43 ,  44  are attracted by the third and second magnetic pole portions  27   b ,  26   b,  respectively. Thus, the plate-shaped pivoting piece  32  is pivoted downward against the spring force of the support spring  33 , so that the movable contact  34  abuts on the anchored contact  36 , and then, the first and second movable iron pieces  43 ,  44  are attached to the third, and second magnetic pole portions  27   b ,  26   b,  respectively, to close the magnetic circuit. Even when the application of the voltage to the coil  23  is released, the magnetic force of the permanent magnet  42  allows the movable block  40  to continue sustaining the operating state, thus continuing electrification. 
         [0045]    Subsequently, when the voltage is applied in a reverse direction of the foregoing direction, a magnetic force generated inside the electromagnet block  20  and the spring force of the support spring  33  slide and move the movable block  40  upward against the magnetic force of the permanent magnet  42 . Thus, the movable contact  34  breaks contact with the anchored contact  36 , and then, the first and second movable iron pieces  43 ,  44  are attached to the first and third magnetic pole portions  25   b,    27   b,  respectively, and return to the original state. 
         [0046]    According to the present embodiment, since the one end portion of the plate-shaped pivoting piece  32  makes linear contact with an edge portion of the upper end portion  31   a  of the movable contact terminal  31 , smooth operating characteristics can be obtained. 
         [0047]    Moreover, even if the edge portion of the upper end portion  31   a  of the movable contact terminal  31  is worn away, since the upper end portion  31   a  is inclined, a so-called shaving effect can be obtained. This advantageously makes it difficult to displace a pivoting fulcrum of the plate-shaped pivoting piece  32 , and assures stable operating characteristics over a long period. 
         [0048]    The electromagnetic relay according to the present invention is not limited to the application to the foregoing self-sustaining electromagnetic relay, but obviously, it may be applied to a self-reset electromagnetic relay. 
         [0049]    There has thus been shown and described an attachment structure of an electromagnetic relay which fulfills all the objects and 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. 
         [0050]    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.