Patent Publication Number: US-6661321-B1

Title: Electromagnetic switch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an electromagnetic switch, more particularly to an electromagnetic switch with a socket, an electromagnetic module, and a contact module that is to be plugged into the socket and the electromagnetic module. 
     2. Description of the Related Art 
     FIGS. 1 and 2 illustrate a conventional electromagnetic switch that includes a housing  3 , first and second electromagnetic members  5 ,  6  mounted in the housing  3 , a fixed contact member mounted in the housing  3  above the first and second electromagnetic members  5 ,  6 , and a movable contact member  8  mounted in the housing  3  above the fixed contact member. Each of the first and second electromagnetic members  5 ,  6  includes a coil  51 , a yoke  41  disposed below the coil  51 , and an armature  61  disposed above the coil  51 . The armature  61  of each of the first and second electromagnetic members  5 ,  6  has a pair of pushing arms  71  extending upwardly therefrom toward and pivoted to the movable contact member  8  via pivot studs  83  which are formed on two opposite ends of the movable contact member  8 . First and second urging members  84 ,  85  are mounted in the housing  3  for respectively urging the opposite ends of the movable contact member  8  in an upward direction. The movable contact member  8  includes first and second movable contacts  821 ,  822 , and is rotatable between a first angular position, in which, the first movable contact  821  is turned downwardly to electrically contact a first fixed contact  311  of the fixed contact member, which results from downward movement of the armature  61  of the first electromagnetic member  5  against an urging action of the first urging member  84  via the yoke  41  of the first electromagnetic member  5  upon actuation of the coil  51  of the first electromagnetic member  5 , and a second angular position, in which, the second movable contact  822  is turned downwardly to electrically contact a second fixed contact  312  of the fixed contact member, which results from downward movement of the armature  61  of the second electromagnetic member  6  against an urging action of the second urging member  85  via the yoke  41  of the second electromagnetic member  6  upon actuation of the coil  51  of the second electromagnetic member  6 . 
     The conventional electromagnetic switch is disadvantageous in that since all of the components thereof are mounted in the housing  3 , the assembly operation is relatively inconvenient and time-consuming. As a consequence, the manufacturing cost of the conventional electromagnetic switch is significantly increased. Moreover, the repair and the mounting and dismounting of a plurality of conductive wires thereon are laborious, and the urging members  84 ,  85  tend to fail after a period of use. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide an electromagnetic switch that dispenses with the use of the aforesaid urging members and that is capable of overcoming the aforesaid drawbacks of the prior art. 
     According to the present invention, there is provided an electromagnetic switch that comprises: an electromagnetic module including a first housing half and first and second electromagnetic members mounted in the first housing half, each of the first and second electromagnetic members including a coil, a yoke, and an armature movable when actuated by the yoke upon application of an electric current to the coil; a contact module including a second housing half connected to the second housing half and having a top wall, the contact module further including a fixed contact member and a movable contact member associated with the electromagnetic module, the fixed contact member being mounted in the second housing half and including conductive first and second fixed contacts and a conductive third fixed contact spaced apart from the first and second fixed contacts, the movable contact member being mounted in the second housing half and including conductive first and second movable contacts which are vertically and respectively aligned with the first and second fixed contacts, and a conductive third movable contact which is electrically connected to the first and second movable contacts and the third fixed contact, the movable contact member being rotatable relative to the fixed contact member among a first angular position, in which the first movable contact is in electrical contact with the first fixed contact, whereas the second movable contact is spaced apart from the second fixed contact when the coil of the first electromagnetic member is actuated, thereby establishing a first circuit passing through the first fixed contact, the first movable contact, the third movable contact, and the third fixed contact, a second angular position, in which the second movable contact is in electrical contact with the second fixed contact, whereas the first movable contact is spaced apart from the first fixed contact when the coil of the second electromagnetic member is actuated, thereby establishing a second circuit passing through the second fixed contact, the second movable contact, the third movable contact, and the third fixed contact, and a normal angular position, in which the first and second movable contacts are spaced apart from the first and second fixed contacts, respectively, when the coils of the first and second electromagnetic members are disabled, each of the first and third fixed contacts having a blade portion extending outwardly through the top wall of the second housing half; and a socket including a socket seat and conductive first and second socket contacts mounted on the socket seat, the socket seat being formed with first and second blade slots for insertion of the blade portions of the first and third fixed contacts and for electrical contact between each of the blade portions and a respective one of the first and second socket contacts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate an embodiment of the invention, 
     FIG. 1 is an exploded perspective view of a conventional electromagnetic switch; 
     FIG. 2 is a schematic view to illustrate how the electromagnetic switch of FIG. 1 works; 
     FIG. 3 is a partly exploded perspective view of a preferred embodiment of an electromagnetic switch according to this invention; 
     FIG. 4 is a bottom perspective view of a socket of the electromagnetic switch of FIG. 3; 
     FIG. 5 is a partly exploded perspective view illustrating an electromagnetic module and a contact module of the electromagnetic switch of FIG. 3; 
     FIG. 6 is an exploded perspective view of the contact module shown in FIG. 5; 
     FIG. 7 is exploded perspective view of the electromagnetic module shown in FIG. 5; 
     FIG. 8 is a partly sectional view to illustrate a movable contact member of the contact module shown in FIG. 5 when disposed at a normal angular position relative to a fixed contact member of the contact module; 
     FIG. 9 is a partly sectional view of the movable contact member of the contact module shown in FIG. 5 when disposed at a first angular position relative to the fixed contact member of the contact module; 
     FIG. 10 is a partly sectional view of the movable contact member of the contact module shown in FIG. 5 when is disposed at a second angular position relative to the fixed contact member of the contact module; 
     FIG. 11 is a fragmentary sectional view of the movable contact member of the contact module shown in FIG. 5, which is disposed at an upper position relative to the fixed contact member of the contact module; 
     FIG. 12 is a fragmentary partly sectional view to illustrate how the contact module is secured to the electromagnetic module shown in FIG. 5; and 
     FIG. 13 is a fragmentary schematic view to illustrate how a socket is plugged into the contact module shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 3 to  8  illustrate a preferred embodiment of an electromagnetic switch according to this invention. The electromagnetic switch includes a socket  100 , an electromagnetic module  300 , and a contact module  200  that is to be plugged into the socket  100  at one side and into the electromagnetic module  300  at an opposite side. 
     The electromagnetic module  300  includes first and second electromagnetic members  22 ,  23  (see FIG.  7 ), each of which includes a coil  222  ( 232 ), a yoke  221  ( 231 ) disposed above the coil  222  ( 232 ), and an armature  223  ( 233 ) disposed below the coil  222  ( 232 ) and movable upwardly when actuated by the yoke  221  ( 231 ) upon application of an electric current to the coil  222  ( 232 ). The electromagnetic module  300  further includes first and second pushing units  224 ,  234  connected to and projecting upwardly and respectively from the armatures  223 ,  233  of the first and second electromagnetic members  22 ,  23 , and co-movable with the armatures  223 ,  233 , respectively. 
     The contact module  200  includes a fixed contact member  12  disposed above the first and second electromagnetic members  22 ,  23  and including pairs of conductive first and second fixed contacts  120 ,  121  (only one pair of the first and second fixed contacts  120 ,  121  will be described in the following paragraphs), and a movable contact member  13  disposed between the electromagnetic module  300  and the fixed contact member  12  and including a movable seat  132  with two opposite sides, and pairs of conductive first and second movable contacts  130 ,  131  (only one pair of the first and second movable contacts  130 ,  131  will be described in the following paragraphs) which are respectively disposed at the opposite sides of the movable seat  132  and which are vertically and respectively aligned with the respective pair of the first and second fixed contacts  120 ,  121 . The movable seat  132  is pivoted to the fixed contact member  12  so as to permit the movable contact member  13  to be rotatable relative to the fixed contact member  12  among a first angular position (see FIG.  9 ), in which the first movable contact  130  is in electrical contact with the first fixed contact  120 , whereas the second movable contact  131  is spaced apart from the second fixed contact  121  when the coil  222  of the first electromagnetic member  22  is actuated, a second angular position (see FIG.  10 ), in which the second movable contact  131  is in electrical contact with the second fixed contact  121 , whereas the first movable contact  130  is spaced apart from the first fixed contact  120  when the coil  232  of the second electromagnetic member  23  is actuated, and a normal angular position (see FIG.  8 ), in which the first and second movable contacts  130 ,  131  are spaced apart from the first and second fixed contacts  120 ,  121 , respectively, when the coils  222 ,  232  of the first and second electromagnetic members  22 ,  23  are disabled. 
     The first and second pushing units  224 ,  234  respectively extend toward the opposite sides of the movable seat  132  in such a manner that the first pushing unit  224  is moved upwardly upon actuation of the armature  223  of the first electromagnetic member  22  so as to move the movable contact member  13  to the first angular position, and that the second pushing unit  234  is moved upwardly upon actuation of the armature  233  of the second electromagnetic member  23  so as to move the movable contact member  13  to the second angular position. 
     The electromagnetic module  300  further includes a first housing half  21  formed with a pair of opposing latch-engaging bars  217 . The contact module  200  further includes a second housing half  11  which is formed with a pair of opposing latches  113  and which is detachably coupled to the first housing half  21  via engagement between each of the latches  113  and a respective one of the latch-engaging bars  217 . An abutting member  1132  is disposed between and abuts against each of the latches  113  and the respective one of the latch-engaging bars  217  so as to tightly secure the first housing half  21  to the second housing half  11  (see FIG.  12 ). The first and second electromagnetic members  22 ,  23  are mounted in the first housing half  21 . The fixed contact member  12  and the movable contact member  13  are mounted in the second housing half  11 . 
     Each of the first and second pushing units  224 ,  234  includes an armature casing  2241  ( 2341 ) with two opposite ends, and a pair of pushing arms  2243  ( 2343 ) extending upwardly and respectively from the opposite ends of the armature casing  2241  ( 2341 ) for moving the movable contact member  13  to a respective one of the first and second angular positions. The first housing half  21  has a top open end  210  defining a top opening  212 . The electromagnetic module  300  further includes a guiding plate  215  mounted on the top open end  210  of the first housing half  21  and covering the top opening  212 , and formed with a plurality of first through-holes  2152  for extension of the pushing arms  2243  ( 2343 ) of the first and second pushing units  224 ,  234  therethrough, respectively, so as to guide upward and downward movements of the first and second pushing units  224 ,  234 . Each of the armatures  223 ,  233  is secured in the respective one of the armature casings  2241 ,  2341  via a latch plate  2245  extending through the armature  223  ( 233 ) and the respective armature casing  2241  ( 2341 ). 
     The coil  222  ( 232 ) of each of the first and second electromagnetic members  22 ,  23  includes a top flange  2220  ( 2320 ) formed with a pair of conductive clamping members  2221  ( 2321 ). The guiding plate  215  is further formed with a plurality of second through-holes  2153  for extension of the clamping members  2221 ,  2321  of the top flanges  2220 ,  2320  of the coils  222 ,  232  of the first and second electromagnetic members  22 ,  23  therethrough, respectively. The fixed contact member  12  further includes a plurality of conductive terminal legs  1211  which are releasably and respectively gripped by the clamping members  2221 ,  2321  so as to permit the contact module  200  to be plugged into the electromagnetic module  300  and so as to permit electrical connection between each of the coils  222 ,  232  of the first and second electromagnetic members  22 ,  23  and electrical wires (not shown) via a respective one of the terminal legs  1211 . 
     The fixed contact member  12  further includes a stationary seat  122  with two opposite sides. The first and second fixed contacts  120 ,  121  are disposed at the opposite sides of the stationary seat  122  of the fixed contact member  12 , respectively. A pair of pivotal lugs  123  extend downwardly from two opposite ends of the stationary seat  122  of the fixed contact member  12  between the first and second fixed contacts  120 ,  121 , and are formed with elongated slots  124 , respectively. The movable seat  132  of the movable contact member  13  further includes a pair of pivot studs  133  that respectively extend into and that are movable within the elongated slots  124  so as to permit pivotal action of the movable contact member  13  relative to the fixed contact member  12  between the first and second angular positions. 
     Referring to FIG. 11, in combination with FIGS. 6 and 8, each of the first and second movable contacts  130 ,  131  of the movable contact member  13  is spaced apart from a respective one of the first and second fixed contacts  120 ,  121  by a vertical length (L) when the movable contact member  13  is disposed at the normal angular position. Each of the elongated slots  124  has a vertical height (H) that is less than the vertical length (L) so as to prevent simultaneous electrical contact between the first movable contact  130  and the first fixed contact  120  and between the second movable contact  131  and the second fixed contact  121  when the coils  222 ,  232  of the first and second electromagnetic members  22 ,  23  are simultaneously actuated. As shown in FIG. 11, the movable contact member  13  is moved upwardly to an upper position, in which, each of the pivot studs  133  abuts against a top end of a slot-confining wall of a respective one of the elongated slots  124 , when the coils  222 ,  232  of the first and second electromagnetic members  22 ,  23  are simultaneously actuated. 
     Referring to FIGS. 3,  6  and  8 , the second housing half  11  has a top wall  111  formed with a plurality of first and second openings  112 . The movable contact member  13  further includes a plurality of conductive bridges  135  (only one of the bridges  135  will be described in the following paragraphs), each of which is mounted on the movable seat  132  and interconnects two of the first and second movable contacts  130 ,  131 , and a plurality of conductive third movable contacts  136  (only one of the third contacts  136  will be described in the following paragraphs), each of which is electrically connected to the respective bridge  135  at a position between the first and second movable contacts  130 ,  131  in such a manner that the first and third movable contacts  130 ,  136  form a first circuit when the movable contact member  13  is disposed at the first angular position, and that the second and third movable contacts  131 ,  136  form a second circuit when the movable contact member  13  is disposed at the second angular position. The fixed contact member  12  further includes a plurality of conductive third fixed contacts  126  (only one of the third fixed contacts  126  will be described in the following paragraphs), each of which is in constant electrical contact with the respective third movable contact  136  via a conductive spring piece  127  so that the first circuit passes through the first fixed contact  120 , the first movable contact  130 , the third movable contact  136 , and the third fixed contact  126 , and that the second circuit passes through the second fixed contact  121 , the second movable contact  131 , the third movable contact  136 , and the third fixed contact  126 . Each of the first and third fixed contacts  120 ,  126  has a blade portion  1201  ( 1261 ) projecting upwardly and outwardly of the second housing half  11  from the stationary seat  122  through a respective one of the first and second openings  112 . 
     The socket  100  includes a socket seat  14  and a plurality of conductive first and second socket contacts  141 ,  142  (only one of the first and second socket contacts  141 ,  142  will be described in the following paragraphs), each of which is mounted on the socket seat  14  for connection to electrical wires (not shown) and each of which has a spring arm portion  1411  (see FIG.  13 ). The socket seat  14  has a bottom formed with first and second blade slots  143  for insertion of the blade portions  1201 ,  1261  of the first and third fixed contacts  120 ,  126  and for electrical contact between each of the blade portions  1201 ,  1261  and the spring arm portion  1411  of a respective one of the first and second socket contacts  141 ,  142 . 
     Since the contact module  200  can be plugged into the socket  100  and the electromagnetic module  300 , the aforesaid drawbacks as encountered in the prior art can be eliminated. Moreover, the electromagnetic switch of this invention dispenses with the use of the aforesaid urging members employed in the conventional electromagnetic switch. 
     With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.