Abstract:
An electromagnetic relay assembly includes a switching unit to push a sliding member and to place a locking portion of a locking member to lock the sliding member at a first position where the switching unit switches a first conductive plate and a second conductive plate to an electrically disconnected state. When a coil is energized, the sliding member is moved to a second position, and the locking portion of the locking member is placed to lock the sliding member in the second position where the switching unit is actuated by the sliding member to switch the first and second conductive plates to an electrically connected state.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Application No. 103111790, filed on Mar. 28, 2014. 
     FIELD OF THE INVENTION 
     The invention relates to an electromagnetic relay assembly, and more particularly to an electromagnetic relay assembly operable to be mechanically positioned between a circuit making position and a circuit breaking position. 
     BACKGROUND OF THE INVENTION 
     A relay in general is an electrically operated switch capable of using a relatively small amount of electrical current to control an electronic device operated under a relatively large electrical current. As shown in  FIGS. 1 and 2 , a conventional magnetic relay includes an iron core  61 , a coil  62  wound around the iron core  61 , and an armature  63  detachably connected to the iron core  61 . When the coil  62  is energized by a small electrical current that passes therethrough, a magnetic field is generated by the iron core  61  due to electromagnetic induction. The armature  63  is magnetically attracted by the iron core  61  to be positioned at a closed position (as shown in  FIG. 1 ), thereby forming a circuit with a relatively large electrical current flowing therethrough. When the coil is de-energized, the electromagnetic induction disappears and the armature  63  is separated from the iron core  61  to reach an open position (as shown in  FIG. 2 ) to break the circuit. However, in order to maintain the circuit at the closed position, the coil  62  has to be continuously energized by continuous application of the electrical current. As a result, a hazard to use of the conventional magnetic relay may arise due to massive production of waste heat and accelerated aging of peripheral elements caused by the waste heat. 
     In order to alleviate the aforesaid drawback, a conventional magnetic latching relay is proposed in Chinese Patent No. CN203038857U. The conventional magnetic latching relay includes a permanent magnet to attract and position an armature at a circuit making position. However, since the armature is positioned only by magnetic attraction of the permanent magnet, the armature may be displaced, arising in safety concerns due to undesired or unavoidable vibration of the relay. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide an electromagnetic relay assembly that may alleviate at least one of the aforesaid drawbacks of the prior art. 
     According to the present invention, an electromagnetic relay assembly includes a housing, an electromagnetic unit, a switch assembly and a switch control unit. 
     The electromagnetic unit is disposed in the housing, and includes a magnetic spool, a coil wound on the magnetic spool, and an armature pivotally disposed on the magnetic spool. 
     The switch assembly includes first and second conductive plates mounted to the housing, and a switching unit disposed in the housing to switch the first and second conductive plates between electrically connected and disconnected states. 
     The switch control unit is disposed between the switching unit and the armature, and includes a sliding member that is slidably disposed in the housing to move between first and second positions, and a locking member. The sliding member is connected to the switching unit and has a guide groove formed with a first locking site and a second locking site. The locking member is movably mounted to the housing and has a locking portion that is inserted into the guide groove to move between the first and second locking sites. 
     The switching unit provides a resilient force to push the sliding member to the first position and to place the locking portion in the first locking site such that the sliding member is locked in the first position where the switching unit switches the first and second conductive plates to the electrically disconnected state. 
     When the coil is energized, the sliding member is moved by the armature to the second position, and the locking portion is placed in the second locking site such that the sliding member is locked in the second position where the switching unit is actuated by the sliding member to switch the first and second conductive plates to the electrically connected state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which: 
         FIG. 1  is a side view of a conventional relay assembly in an energized state; 
         FIG. 2  is a side view of the conventional relay assembly in a de-energized state; 
         FIG. 3  is an exploded perspective view of the first embodiment of an electromagnetic relay assembly according to the present invention; 
         FIG. 4  is a schematic view of the first embodiment illustrating a sliding member of the electromagnetic relay assembly; 
         FIG. 5  is a sectional view of the first embodiment illustrating a connection relationship between a locking member and the sliding member of the electromagnetic relay assembly; 
         FIG. 6  is a rear view of the first embodiment; 
         FIG. 7  is a partly sectional front view of the first embodiment illustrating the sliding member in a first position, the locking member in a first locking site, and a passive plate spaced apart from a second conductive plate of a switch assembly of the electromagnetic relay assembly; 
         FIG. 8  is a partly sectional front view similar to  FIG. 7 , illustrating the sliding member moving to a second position and the locking member moving to a second locking site; 
         FIG. 9  is a partly sectional front view similar to  FIG. 7 , illustrating the sliding member continuing to move to the second position, and the locking member continuing to move to the second locking site such that the passive plate is connected to the second conductive plate; 
         FIG. 10  is a partly sectional front view similar to  FIG. 7 , illustrating the sliding member being locked in the second position, and the locking member being positioned in the second locking site, such that the passive plate is still connected to the second conductive plate; 
         FIG. 11  is a sectional view illustrating the sliding member connected to the switch assembly when the passive plate is still connected to the second conductive plate; 
         FIG. 12  is a perspective view illustrating the second embodiment of an electromagnetic relay assembly according to the present invention; and 
         FIG. 13  is a perspective view illustrating the third embodiment of an electromagnetic relay assembly according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIGS. 3 to 5 , the first embodiment of an electromagnetic relay assembly according to the present invention is illustrated. The electromagnetic relay assembly includes a housing, an electromagnetic unit  3 , a switch control unit  4  and a switch assembly  5 . 
     The housing has a housing base  1  and a housing cover  2  detachably covering the housing base  1 . 
     The electromagnetic unit  3  is disposed in the housing and includes a magnetic spool  31 , a coil  32  wound on the magnetic spool  31 , and an armature  34  pivotally disposed on the magnetic spool  31 . In the first embodiment, the electromagnetic unit  3  further includes two terminals  33  electrically coupled to the coil  32  for receiving an external current signal. In this embodiment, the electromagnetic unit  3  is mounted on the housing base  1 . When the coil  32  is electrified or energized, the magnetic spool  31  is excited to generate a magnetic field such that the armature  34  is magnetically attracted by the magnetic spool  31 . 
     In the first embodiment, the switch control unit  4  is disposed between the switching unit  5  and the armature  34 , and includes a sliding groove  41 , a sliding member  42  slidably disposed in the housing, a locking member  43  and a retaining plate  44 . 
     The sliding groove  41  is formed in the housing base  1 . In this embodiment, the sliding groove  41  is disposed parallel to an axial direction of the magnetic spool  31 . 
     Referring to  FIGS. 4 to 6 , the sliding member  42  is slidably disposed in the sliding groove  41  to be movable between first and second positions and is connectable to the armature  34 . The sliding member  42  includes a guide groove  422  that is formed with a first locking site  426  and a second locking site  427 . In this embodiment, the sliding member  42  is formed with an elongate opening  421  that is spaced apart from the guide groove  422 . The sliding member  42  may be made of an insulating plastic material to avoid a short circuit or an electrical discharge caused by friction during transport. 
     The guide groove  422  is annular and has a groove wall  4221  opposite to an opening of the guide groove  422 . The groove wall  4221  is formed with a plurality of inclined tooth-like portions  423  that are arranged annularly. In this embodiment, the guide groove  422  has an outer profile substantially conforming to a heart shape. Alternatively, the guide groove  422  may be configured to have other shapes, such as a lightning shape or a triangle shape. 
     In the first embodiment, each of the inclined tooth-like portions  423  has a slanting surface  424  and a shoulder surface  425  adjoining the slanting surface  424  of an adjacent one of the inclined tooth-like portions  423 . The first and second locking sites  426 , 427  are aligned with each other along an axis (L) of symmetry of the guide groove  422 . Each of the first and second locking sites  426 ,  427  is situated on the shoulder surface  425  of one of the inclined tooth-like portions  423 . 
     The locking member  43  is movably mounted to the housing, and has a locking portion  432  that is inserted into the guide groove  422  to move between the first and second locking sites  426 ,  427 . When the locking portion  432  slides along the groove wall  4221  to one of the first and second locking sites  426 ,  427 , the shoulder surface  425  prevents a backward movement of the locking portion  432 , so that the locking portion  432  moves only forward to slide along the inclined tooth-like portions  423  one after the other. 
     In the first embodiment, the locking member  43  further has a pivot portion  431  inserted movably into the elongate opening  421 . The pivot portion  431  may pivotally extend through the housing base  1  to the elongate opening  421 . In such an arrangement, the pivot portion  431  not only guides the sliding movement of the sliding member  42 , but also prevents separation of the locking member  43  from the housing base  1 . 
     In the first embodiment, the retaining plate  44  urges the locking portion  432  to contact against the groove wall  4221  so as to prevent the locking portion  432  of the locking member  43  from being separated from the annular groove  422 . 
     When the sliding member  42  is in the first position, the locking portion  432  of the locking member  43  is positioned to the first locking site  426  (as shown in  FIG. 7 ). When the coil  32  is electrified or energized and the magnetic spool  31  is excited to magnetically attract the armature  34 , the sliding member  42  is driven by the armature  34  to slide downward along the sliding groove  41  (as shown in  FIGS. 8 and 9 ) and moves to the second position. When the coil  32  is not electrified, the locking portion  432  of the locking member  43  is positioned in the second locking site  427  and the sliding member  42  is locked in the second position (as shown in  FIG. 10 ). 
     Referring to  FIGS. 3, 7 and 11 , the switch assembly  5  includes first and second conductive plates  51 ,  52  mounted to the housing, and a switching unit  56  disposed in the housing to switch the first and second conductive plates  51 ,  52  between electrically connected and disconnected states. In the first embodiment, the sliding member  42  is connected to the switching unit  56 . In addition, the switch assembly  5  further includes a first contact member  54  disposed in the housing, and a second contact member  55  mounted on the second conductive plate  52 . In this embodiment, the switch assembly  5  and the electromagnetic unit  3  are electrically isolated from each other. The first and second conductive plates  51 ,  52  are mounted to the housing base  1  and are spaced apart from each other. 
     In the first embodiment, the first contact member  54  is mounted to the housing base  1  and is aligned in a spaced-apart manner with the second contact member  55 . 
     The switching unit  56  is connected to the first conductive plate  51 , and has a conductive substrate  561 , an active plate  562  and a passive plate  565 . The conductive substrate  561 , the active plate  562  and the passive plate  565  may be made of a metal material so as to enable flow of the electrical current therethrough. 
     In the first embodiment, the conductive substrate  561  is mounted on the housing base  1  and is connected to the first conductive plate  51 . 
     The active plate  562  is connected between the conductive substrate  561  and the sliding member  42 . The active plate  562  has a connection portion  563  pivotally connected to the conductive substrate  561 , and a force-transmitting portion  564  in contact with the sliding member  42 . 
     The passive plate  565  is connected to the conductive substrate  561 . Preferably, the passive plate  565  is connected to the active plate  562  to make electrical contact with the second conductive plate  52 . When the sliding member  42  slides between the first position and the second position, the passive plate  565  is movable relative to the conductive substrate  561 . In the first embodiment, the passive plate  565  has a contact portion  566  to connect to the second conductive plate  52 , and a force-receiving portion  567  distal from the contact portion  566 . The contact portion  566  of the passive plate  565  is connectable to one of the first contact member  54  and the second contact member  55 . The force-receiving portion  567  of the passive plate  565  and the force-transmitting portion  564  of the active plate  562  are connected to each other. When the sliding member  42  is in the first position, the contact portion  566  of the passive plate  565  is connected to the first contact member  54 . In such a condition, the passive plate  565  is disconnected from the second conductive plate  52 , and thus the first conductive plate  51  is not electrically coupled to the second conductive plate  52 . When the sliding member  42  is in the second position, the contact portion  566  of the passive plate  565  is connected to the second contact member  54 . As a result, the passive plate  565  is connected to the second conductive plate  52 , and thus the first conductive plate  51  is electrically coupled to the second conductive plate  52 . 
     In the first embodiment, the switching unit  56  further has a resilient plate  45  connected between the conductive substrate  561  and the passive plate  565 . In this embodiment, the resilient plate  45  is a curved plate spring made of a metal material, and is compressed when the resilient plate  45  is assembled between the conductive substrate  561  and the contact portion  566  of the passive plate  565 . As a result, when the sliding member  42  is in the first position, the resilient plate  45  pushes upward the passive plate  565  to contact against the first contact member  54 . When the sliding member  42  is in the second position, the resilient plate  45  pushes downward the passive plate  565  to contact against the second contact member  55 . 
       FIG. 12  illustrates the second embodiment of an electromagnetic relay assembly according to the present invention, which has a configuration similar to that of the first embodiment. However, in the second embodiment, the first and second conductive plates  51 ,  52  are aligned with and spaced apart from each other relative to the housing base  1 . 
       FIG. 13  illustrates the third embodiment of an electromagnetic relay assembly according to the present invention, which has a configuration similar to that of the second embodiment. However, in the third embodiment, the switch assembly  5  further includes a third conductive plate  53  disposed at the housing base  1  in the housing. The first contact member  54  is mounted on the third conductive plate  53 . When the sliding member  42  is in the first position, the switching unit  56  contacts the first contact member  54 , such that the first conductive plate  51  is electrically coupled to the third conductive plate  53 . When the sliding member  42  is in the second position, the switching unit  56  contacts the second contact member  55 , such that the first conductive plate  51  is electrically coupled to the second conductive plate  52 . In the third embodiment, the first conductive plate  51  can serve as a relay common output (COM). The second conductive plate  52  can serve as a relay normally open output (NO). The third conductive plate  53  can serve as a relay normally closed output (NC). 
     To sum up, the electromagnetic relay assembly according to the present invention provides the following advantages and effects: 
     1. By virtue of sliding of the locking portion  432  of the locking member  43  in the guide groove  422 , the sliding member  42  can be assuredly locked in the first position or in the second position, and the switch assembly  5  can therefore be constantly switched to the electrically connected or disconnected state. 
     Accordingly, even in a severe vibration environment, the electromagnetic relay according to the present invention is safe to use. 
     2. By virtue of the resilient member  45 , the contact portion  566  of the passive plate  565  can be biased to move between the first contact member  54  and the second contact member  55  and to contact tightly against the first contact member  54  or the second contact member  55  without requiring additional positioning elements, thereby reducing the spatial volume to accommodate assembly components. 
     3. By virtue of the third conductive plate  53  in the third embodiment, the electromagnetic relay assembly may have two operating circuits, thereby increasing flexibility during use. 
     While the present invention has been described in connection with what are considered the most practical embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.