Patent Publication Number: US-2021175031-A1

Title: Direct current relay

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2019/010278, filed on Aug. 13, 2019, which claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0103724 filed on Aug. 31, 2018, the contents of which are all hereby incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a direct current relay and, more particularly, to a direct current relay including a mover assembly having improved contact pressure. 
     BACKGROUND 
     In general, a direct current relay or a magnetic switch is a kind of electrical circuit switching device that allows mechanical operation and transmits current signal using principles of electromagnet, and is installed in various industrial facilities, machines, and vehicles. 
     In particular, electric vehicles such as hybrid vehicles, fuel cell vehicles, golf carts, and electric forklifts are equipped with an electric vehicle relay to supply and cut off power of a battery to a power generating device and an electrical equipment. And, such an electric vehicle relay is one of very important core components in electric vehicles. 
       FIG. 1  illustrates an internal structure of a direct current relay according to the related art. 
     The direct current relay includes a case  1 ,  2  including an upper frame  1  and a lower frame  2 , a middle plate  9  provided inside the case, a contact portion  3 ,  4  and an arc-extinguishing portion  8  both installed above the middle plate  9 , and an actuator  7  installed under the middle plate  9 . Here, the actuator  7  may be a device that operates by the principles of electromagnet. 
     At an upper surface of the upper frame  1 , a fixed contact  3  of the contact portion  3 ,  4  is exposed so as to be connected to a load or power source. 
     The contact portion  3 ,  4  and the arc-extinguishing portion  8  are provided inside the upper frame  1 . The contact portion  3 ,  4  includes the fixed contact  3  fixedly installed in the upper frame  1 , and a movable contact  4  actuated by the actuator  7  so as to be brought into contact with or separated from the fixed contact  3 . The arc-extinguishing portion  8  is usually made of a ceramic material. The arc-extinguishing portion  8  is also referred to as an arc chamber. Inside the arc-extinguishing portion  8 , there may be filled with extinguishing gas for arc extinguishing. 
     To effectively control an arc generated when the contact portion  3 ,  4  is cutoff (or separated), a permanent magnet (not illustrated) may be provided. The permanent magnet is installed around the contact portion to generate a magnetic field to control the arc, which is a rapid flow of electricity, and a permanent magnet holder  6  is provided to fix the permanent magnet. 
     The actuator is operated using the principles of electromagnet and includes a fixed core  7   a , a movable core  7   b , a movable shaft  7   c , and a return spring  7   d . A cylinder  7   e  surrounds the fixed core  7   a  and the movable core  7   b . The cylinder  7   e  and the arc-extinguishing portion  8  form a closed space. 
     A coil  7   f  is provided around the cylinder  7   e , and when a control power is applied, an electromagnetic force is generated around the cylinder  7   e . The fixed core  7   a  is magnetized by the electromagnetic force generated by the coil  7   f , and the movable core  7   b  is attracted by a magnetic force of the fixed core  7   a . Accordingly, the movable shaft  7   c  coupled to the movable core  7   b  and the movable contact  4  coupled to an upper portion of the movable shaft  7   c  move together to be brought into contact with the fixed contact  3  so that the circuit is energized. The return spring  7   d  provides an elastic force to the movable core  7   b  to allow the movable core  7   b  to return to its initial position when the control power of the coil is cut off. 
     However, in the direct current relay according to the related art, an electromagnetic repulsive force is generated between the fixed contact and the movable contact, and thus the fixed contact and the movable contact tend to be separated from each other. In order to prevent unintentional separation due to such an electromagnetic repulsive force, the movable contact  4  receives a contact pressure from a contact pressure spring  5 . In other words, a distance between the fixed core  7   a  and the movable core  7   b  is set longer than a distance between the fixed contact  3  and the movable contact  4 , so that the movable contact receives a contact pressure due to an over travel of the movable core. However, when the electromagnetic repulsive force is stronger than the contact pressure, there is still a risk of separation of the contact portion. 
     SUMMARY 
     The present disclosure is to solve those problems, and an aspect of the present disclosure is to provide a magnetic contactor provided with a mover assembly that improves a contact pressure. 
     A direct current relay according to an aspect of the present disclosure including a pair of fixed contacts and a movable contact moved vertically by an actuator to be brought into contact with or be separated from the pair of fixed contacts, includes a mover support disposed below the movable contact and connected to the actuator by a shaft, a mover holder disposed above the movable contact and fixed to the mover support, an upper yoke and a lower yoke respectively disposed above and below the movable contact to generate an electromagnetic force, and a contact pressure spring disposed between the lower yoke and the mover support, wherein the upper yoke and the lower yoke form a magnetic circuit to offset an electromagnetic repulsive force generated between the fixed contacts and the movable contact. 
     Here, an upper end of the shaft is provided with a coupling portion inserted into the mover support. 
     In addition, the mover support includes a first flat plate portion, and arm portions protruding upwardly from opposite side ends of the first flat plate portion to which the mover holder is fixed. 
     In addition, an upper portion of the first flat plate portion is provided with a spring support portion protruding therefrom to support a lower end of the contact pressure spring. 
     In addition, the mover holder includes a second flat plate portion, and side surface portions bent downwardly at opposite side ends of the second flat plate portion. 
     In addition, a lower surface of the second flat plate portion is provided with a support portion protruding therefrom, and the support portion is inserted in a support groove formed at an upper surface of the movable contact. 
     In addition, a length (or a depth) of each of the support portion and the support groove is greater than an over travel length of the movable contact. 
     In addition, the side surface portions include first side surface portions extending downwardly from opposite ends of the second flat plate portion, and second side surface portions each extending downwardly from the first side surface portion, wherein a width of the second side surface portion is greater than a width of the first side surface portion. 
     In addition, a thickness of the mover holder is smaller than a thickness of the mover support. 
     In addition, a lower surface of the lower yoke is provided with an insertion groove into which an upper end portion of the contact pressure spring is inserted. 
     In addition, the upper yoke includes a third flat plate portion, and wing portions extending downwardly from opposite ends of the third flat plate portion so as to be fitted into the mover holder. 
     In addition, a lower surface of the movable contact is provided with a yoke insertion groove into which the lower yoke is partially inserted. 
     In addition, the upper yoke is disposed on an upper portion or a lower portion of the mover holder. 
     A direct current relay according to another aspect of the present disclosure includes a pair of fixed contacts, and a mover assembly moved vertically by an actuator to be brought into contact with or separated from the pair of fixed contacts so as to energize or cut off a circuit, wherein the mover assembly includes a mover support connected to the actuator by a shaft, a mover holder fixed to an upper portion of the mover support, a movable contact installed between the mover holder and the mover support, and an upper yoke and a lower yoke respectively provided on an upper portion and a lower portion of the movable contact to generate an electromagnetic force, and wherein the mover assembly is arranged such that the upper yoke, the mover holder, the movable contact, the lower yoke, and the mover support are sequentially arranged from top to bottom, or the mover holder, the upper yoke, the movable contact, the lower yoke, and the mover support are sequentially arranged from top to bottom. 
     According to a direct current relay according to an embodiment of the present disclosure, since a movable contact is provided with an upper yoke and a lower yoke to offset an electromagnetic repulsive force, a contact portion is not unintendedly separated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of an internal structure of a direct current relay according to the related art. 
         FIG. 2  is a view of an internal structure of a direct current relay according to an embodiment of the present disclosure. 
         FIG. 3  is a side view of a mover assembly in  FIG. 2 . 
         FIG. 4  is an exploded perspective view of the mover assembly of  FIG. 3 . 
         FIG. 5  is a front sectional view of a mover assembly applied to a direct current relay according to another embodiment of the present disclosure. 
         FIG. 6  is a side view of a mover assembly applied to a direct current relay according to still another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings, but this is to explain in detail enough for those skilled in the art to easily implement the disclosure, and it does not mean that the technical idea and scope of the disclosure are limited thereto. 
       FIG. 2  is a view of an internal structure of a direct current relay according to an embodiment of the present disclosure,  FIG. 3  is a side view of a mover assembly in  FIG. 2 , and  FIG. 4  is an exploded perspective view of the mover assembly of  FIG. 3 . Hereinafter, a direct current relay according to each embodiment of the present disclosure will be described in detail with reference to the drawings. 
     A direct current relay according to an aspect of the present disclosure including a pair of fixed contacts  14  and a movable contact  50  moved vertically by an actuator  60  to be brought into contact with or be separated from the pair of fixed contacts  14 , includes a mover support  40  disposed below the movable contact  50  and connected to the actuator  60  by a shaft  57 , a mover holder  44  disposed above the movable contact  50  and fixed to the mover support  40 , an upper yoke  31  and a lower yoke  35  respectively disposed above and below the movable contact  50  to generate an electromagnetic force, and a contact pressure spring  55  disposed between the lower yoke  35  and the mover support  40 , wherein the upper yoke  31  and the lower yoke  35  form a magnetic circuit to offset an electromagnetic repulsive force generated between the fixed contacts  14  and the movable contact  40 . 
     A frame  11 ,  12  is defined as a box-shaped case to contain, protect, and support components therein. The frame  11 ,  12  may include an upper frame  11  and a lower frame  12 . 
     An arc chamber  13  is defined in a box shape with an open lower surface, and is installed inside the upper frame  11 . The arc chamber  13  is made of a material having excellent insulating property, pressure resistance, and heat resistance so as to extinguish an arc generated at the contact portion  14 ,  50  upon cutoffs. For example, the arc chamber  13  may be made of a ceramic material. The arc chamber  13  is fixedly installed above a middle plate  70 . 
     The fixed contacts  14  are provided in a pair and fixedly installed on the arc chamber  13 . The pair of fixed contacts  14  is exposed at the upper frame  11 . One of the fixed contacts  14  may be connected to a power side, and another one of the fixed contacts  14  may be connected to a load side. 
     The movable contact  50  is defined as a plate-shaped body having a predetermined length, and is installed under the pair of fixed contacts  14 . The movable contact  50  is installed in a mover assembly  30  to be moved integrally. Accordingly, the movable contact  50  moves linearly up and down by the actuator  60  installed inside the lower frame  12  to connect or disconnect a circuit by being brought into contact with or separated from the fixed contacts  14 . 
     To effectively control the arc generated when the contact portion  14 ,  50  is cutoff (or separated), a permanent magnet (not illustrated) is provided. The permanent magnet is installed around the contact portion  14 ,  50  to generate a magnetic field to control the arc, which is a rapid flow of electricity. And, to fix the permanent magnet, a permanent magnet holder  15  is provided. 
     The actuator  60  is provided to move the mover assembly  30 , that is, the movable contact  50 . The actuator  60  may include a yoke  61  defined in a ‘U’ shape and forming a magnetic circuit, a coil  63  wound around a bobbin  62  installed inside the yoke  61  to generate a magnetic field by receiving an external power source, a fixed core  65  fixedly installed inside the coil  63  to generate a magnetic attraction force by being magnetized due to a magnetic field generated by the coil  63 , a movable core  67  installed to be linearly movable under the fixed core  65  so as to be brought into contact with or separated from the fixed core  65  by the magnetic attraction force of the fixed core  65 , a shaft  57  in which a lower end thereof is coupled to the movable core  67  and an upper end thereof is slidably inserted through the movable contact  50 , a return spring  69  installed between the fixed core  65  and the movable core  67  so as to move the movable core  67  downwardly back to its original position, and a cylinder  68  to accommodate the fixed core  65 , the movable core  67 , and the return spring  69 . 
     Between the actuator  60  and the arc chamber  13 , there is provided the middle plate  70 . The middle plate  70  is installed at an upper portion of the yoke  61  and made of a magnetic material to form a magnetic circuit together with the yoke  61 . The middle plate  70  also serves as a support plate on which the arc chamber  13  at the upper portion and the actuator  60  at the lower portion may be installed, respectively. The cylinder  68  may be hermetically coupled to a bottom portion of the middle plate  70 . 
     Between the middle plate  70  and the arc chamber  13 , there may be provided a sealing member  72 . The sealing member  72  is provided along a lower circumference of the arc chamber  13  to seal a space formed by the arc chamber  13 , the middle plate  70  (a hole in a central portion of the middle plate), and the cylinder  68 . 
     The mover assembly  30  includes the shaft  57 , the mover support  40 , the mover holder  44 , the movable contact  50 , the contact pressure spring  55 , the upper yoke  31 , and the lower yoke  35 . 
     The shaft  57  is implemented as a straight rod. A lower end of the shaft  57  is fixedly installed in the movable core  67 . Accordingly, the shaft  57  moves up and down together with the movable core  67  according to a movement of the movable core  67  to thereby allow the movable contact  50  to be brought into contact with or separated from the fixed contact  14 . 
     At an upper end portion of the shaft  57 , a coupling portion  58  is formed. The coupling portion  58  may be defined in a plate shape, for example, a disk shape. The coupling portion  58  of the shaft  57  is fixedly coupled inside the mover support  40 . The coupling portion  58  of the shaft  57  may be manufactured in, for example, an insert-molding manner in which the coupling portion  58  is coupled into the mover support  40 . 
     The mover support  40  with the shaft  57  fixedly installed thereon is provided to support the movable contact  50  and the likes. The mover support  40  includes a first flat plate portion  41 , and arm portions  42  protruding upwardly from opposite side ends of the first flat plate portion  41 . 
     An upper surface of the first flat plate portion  41  of the mover support  40  is provided with a spring support portion  43  protruding therefrom. 
     At the arm portion  42  of the mover support  40 , the mover holder  44  fixedly installed. 
     When viewed from front (see  FIGS. 2 and 4 ), a length (in a left-right direction) of the first flat plate portion  41  is shorter than a length (in the left-right direction) of the movable contact  50 . Accordingly, contact tips of the movable contact  50  are exposed to opposite sides of the mover support  40 , respectively. 
     A width (in a front-rear direction) of an inner surface (or the upper surface) of the first flat plate portion  41  may be smaller than a width (in the front-rear direction) of the movable contact  50 . Accordingly, the mover holder  44  may be stably inserted into the arm portion  42  of the mover support  40  (see  FIG. 3 ). 
     The mover holder  44  is provided to support the movable contact  50 , the upper yoke  31 , and the lower yoke  35 . 
     The mover holder  44  is fixedly installed on the mover support  40 . The mover holder  44  is defined in a ‘⊏’ shape. That is, the mover holder  44  includes a second flat plate portion  45  and opposite side surface portions  46 . The opposite side surface portions  46  are bent downwardly at opposite side ends of the second flat plate portion  45 . 
     A width (or a length in the left-right direction) of the second flat plate portion  45  may be smaller than the length of the movable contact  50 . Accordingly, contact tips of the movable contact  50  are exposed to opposite sides of the mover holder  44 , respectively. 
     A lower surface of the second flat plate portion  45  is provided with a support portion  48  protruding therefrom. The support portion  48  may be defined in a cylindrical shape. The support portion  48  is inserted in a support groove  51  of the movable contact  50 . A height (or a length) of the support portion  48  and a depth of the support groove  51  are greater than an over travel distance, that is, a distance determined by subtracting a distance between the contact portions  14  and  50  from a distance in which the movable core  67  is moved. Accordingly, even if the movable contact  50  is separated from the mover holder  44 , the movable contact  50  does not escape from the mover holder  44 . 
     The side surface portion  46  may include a first side surface portion  46   a  extending downwardly from the second flat plate portion  45 , and a second side surface portion  46   b  extending downwardly from the first side surface portion  46   a.    
     A width (or a length in the left-right direction) of the first side surface portion  46   a  may be equal to the width of the second flat plate portion  45 . 
     A width of the second side surface portion  46   b  is greater than the width of the first side surface portion  46   a . In other words, the widths of the second flat plate portion  45  and the first side surface portion  46   a  are smaller than the width of the second side surface portion  46   b . In addition, a thickness of the mover holder  44  is smaller than a thickness of the mover support  40 . Accordingly, a coupling force in which the mover holder  44  is fixed to the mover support  40  may be maintained while reducing its weight. 
     The second side surface portion  46   b  is provided with a plurality of holes  47 . Accordingly, a bonding force may increase in an insert-molding structure. 
     A lower end portion of the second side surface portion  46   b  is bent inwardly. Accordingly, a bonding force may increase when the mover holder  44  is coupled to the mover support  40  in an insert-molding manner. 
     The movable contact  50  is installed to be brought into contact with a lower surface of the second flat plate portion  45 . The movable contact  50  may not be fixed to the mover holder  44  and may be separable from the mover holder  45 . Accordingly, when the mover assembly  30  moves upward, the movable contact  50  is separated from the second flat plate portion  45  so as to be brought into close contact with the fixed contact  14  by receiving a contact pressure from the contact pressure spring  55 . 
     An upper surface of the movable contact  50  is provided with the support groove  51 . The support portion  48  of the mover holder  44  is inserted in the support groove  51 . The depth of the support groove  51  is preferably formed deeper (or longer) than a length of the support portion  48 . 
     The lower yoke  35  is installed under the movable contact  50 . The lower yoke  35  may be defined in a plate shape. The contact pressure spring  55  applies a contact pressure to the movable contact  50  through the lower yoke  35 . Accordingly, the contact pressure spring  55  may apply a contact pressure without damaging the movable contact  50 , thereby improving safety. 
     The lower yoke  35  is provided with an insertion groove  36  into which the contact pressure spring  55  may be mounted. Since an upper end of the contact pressure spring  55  is fitted into the insertion groove  36  of the lower yoke  35 , the contact pressure spring  55  does not escape from the lower yoke  35  and an operation stability is improved. 
     The upper yoke  31  is installed at an upper portion of the mover holder  44 . The lower yoke  31  may include a third flat plate portion  32 , and wing portions  33  extending downwardly from opposite side ends of the third flat plate portion  32 . 
     The upper yoke  31  is coupled to the mover holder  44 . For example, the upper yoke  31  may be fitted onto the mover holder  44 . The upper yoke  31  may be fitted onto the second flat plate portion  45  and the first side surface portion  46   a  of the mover holder  44 . 
     Between the upper yoke  31  and the mover holder  44  may be caulked to reinforce their coupling force. For example, a caulking protrusion  34  may be formed on an inner side surface of the wing portion  33  of the upper yoke  31 . 
     When the circuit is energized, the upper yoke  31  and the lower yoke  35  respectively provided above and below the movable contact  50  are magnetized, and the lower yoke  35  receives a force drawn by the upper yoke  31 . Accordingly, the movable contact  50  receives a force upwardly to offset an electromagnetic repulsive force. 
     The contact pressure spring  55  is provided between the lower yoke  35  and the mover support  40 . The contact pressure spring  55  is provided to support the movable contact  50  and provide a contact pressure to the movable contact  50  when energized. The contact pressure spring  55  may be implemented as a compression coil spring. 
     Since the contact pressure spring  55  is brought into direct contact with the lower yoke  35 , it does not damage the movable contact  50 . And, this increases durability. 
     Hereinafter, a direct current relay according to another embodiment of the present disclosure will be described with reference to  FIG. 5 . 
     Components other than a mover holder  44  and a movable contact  50  in a mover assembly  30 A of this embodiment may be same as or similar to those in the previous embodiment. 
     Unlike the previous embodiment, the mover holder  44  is not provided with the support portion  48 , and the movable contact  50  is not provided with the support groove  51 . 
     Instead, a lower surface of the movable contact  50  is provided with a yoke insertion groove  52 . The lower yoke  35  is fitted into the yoke insertion groove  52 . As the movable contact  50  is inserted into the yoke insertion groove  52  and moves together with the lower yoke  35 , the movable contact  50  does not escape from the lower yoke  35 . 
     Hereinafter, a direct current relay according to still another embodiment of the present disclosure will be described with reference to  FIG. 6 . 
     Components other than a mover holder  44  and an upper yoke  31  in a mover assembly  30 B of this embodiment may be same as or similar to those in the previous embodiment. 
     In this embodiment, the upper yoke  31  is disposed below the mover holder  44 . In other words, the upper yoke  31  is disposed between the mover holder  44  and the movable contact  50 . Respective size of the mover holder  44  and the upper yoke  31  is changed appropriately. A central portion of the upper yoke  31  is provided with a through hole  32   a , and a support portion  48  of the upper yoke  44  is inserted therethrough. As the upper yoke  31  and the lower yoke  35  surround the movable contact  50  and are disposed more closely, an electromagnetic force may be increased. 
     A main difference between this embodiment and a first embodiment is an arrangement order. In the first embodiment, the upper yoke  31 , the mover holder  44 , the movable contact  50 , the lower yoke  35 , and the mover support  40  are sequentially arranged from top to bottom. However, in this embodiment, the mover holder  44 , the upper yoke  31 , the movable contact  50 , the lower yoke  35 , and the mover support  40  are sequentially arranged from top to bottom. 
     According to the direct current relay according to each of the embodiments of the present disclosure, since the movable contact is provided with the upper yoke and the lower yoke to offset an electromagnetic repulsive force, the contact portion is not unintendedly separated. 
     The foregoing embodiments are to implement embodiments of the present disclosure. Therefore, those skilled in the art to which the present disclosure pertains various modifications and variations will be possible without departing from the essential characteristics of the present disclosure. Therefore, the embodiments disclosed in the present disclosure are not intended to limit the to technical idea of the present disclosure but to describe the present disclosure, and the scope of the technical idea of the present disclosure is not limited by these embodiments. The true scope of the present disclosure should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present disclosure.