Patent Publication Number: US-2022223362-A1

Title: Direct current relay

Description:
FIELD 
     The present disclosure relates to a direct current (DC) relay, and more specifically, a DC relay having a structure capable of setting a direction of electromagnetic force for extinguishing arc regardless of polarity of a fixed contact, and increasing driving force for moving a movable contact to be brought into contact with the fixed contact. 
     BACKGROUND ART 
     A direct current (DC) relay is a device that transmits a mechanical driving signal or a current signal using the principle of an electromagnet. The DC relay is also called a magnetic switch, and is generally classified as an electrical circuit switching device. 
     Referring to  FIGS. 1 to 3 , a DC relay  1000  according to the related art includes a contact part  1100 , permanent magnets  1200 , and a core part  1300 . 
     The contact part  1100  includes a fixed contact  1110  and a movable contact  1120 . When control power is applied, the movable contact  1120  is moved toward the fixed contact  1110  to be brought into contact with the fixed contact  1110 . Accordingly, the DC relay  1000  can be electrically connected to external power supply and load. 
     Driving force for moving the movable contact  1120  is generated by the core part  1300 . When control power is applied, coils  1350  wound around a bobbin  1340  generates an electromagnetic field. At this time, a fixed core  1310  is magnetized and attractive force is generated between the fixed core  1310  and a movable core  1320 . 
     Since the fixed core  1310  is fixed, the movable core  1320  is moved toward the fixed core  1310 . At this time, the movable core  1320  is moved upward together with a shaft  1330  connected to the movable core  1320 . Accordingly, the fixed contact  1110  and the movable contact  1120  can be brought into contact with each other. 
     When the control power is not applied any more, the attractive force between the fixed core  1310  and the movable core  1320  is eliminated. As the movable core  1320  is moved upward, a spring  1321  is compressed and stores restoring force. When the attractive force disappears, the spring  1321  is tensioned. Accordingly, the fixed contact  1110  and the movable contact  1120  are spaced apart from each other, thereby generating arc. 
     The generated arc is extinguished through a preset path and must be discharged to the outside of the DC relay  1000 . To this end, the DC relay  1000  includes the permanent magnets  1200  for generating an electromagnetic field. 
     Referring to (a) of  FIG. 1 , a plurality of fixed contacts  1110  are provided. Current is introduced into an inside of the DC relay  1000  through a fixed contact  1110   a  on the right, flows through the movable contact  1120 , and then is discharged to an outside of the DC relay  1000  through a fixed contact  1110   b  on the left. 
     At this time, the permanent magnets  1200  are disposed at the outside of the fixed contacts  1110   a  and  1110   b , respectively, to generate magnetic fields. 
     Referring to  FIG. 2 , directions of flows of current and force generated by the magnetic fields are shown. That is, the current is applied to the right fixed contact  1110   a  as illustrated in (a) of  FIG. 1 . 
     In addition, a right permanent magnet  1200   a  is arranged so that an S pole is located inward, and a left permanent magnet  1200   b  is arranged so that an N pole is located inward. Accordingly, the magnetic field is generated in a direction from the left to the right. 
     According to the Fleming&#39;s left-hand rule, electromagnetic force, magnetic field, and current are generated at right angles. Accordingly, the electromagnetic force is generated in a direction A by the current application and the arrangement of the permanent magnets  1200 . As a result, arc is extinguished while moving in the direction A. Conversely, when current is applied to the left fixed contact  1110   b , the electromagnetic force is generated in a direction B. 
     At this time, the electromagnetic forces generated by the permanent magnets  1200  are inversely proportional to the square of a distance between the permanent magnets  1200 . Accordingly, when the distance between the permanent magnets  1200  increases, the electromagnetic forces that are insufficient to form an arc extinguishing path may be generated. 
     In addition, strength of the magnetic fields generated by the permanent magnets  1200  is affected by size and thickness of the permanent magnets  1200 . However, considering a limited space inside the DC relay  1000 , it is difficult to increase the size and thickness of the permanent magnet  1200  indefinitely. 
     Therefore, such space limitation causes lots of limits in designing the size and thickness of the permanent magnets  1200  and the distance between the permanent magnets  1200 . Therefore, a method for ensuring magnetic force between the permanent magnets  1200  is required. 
     Also, referring to  FIG. 3 , a direction of driving force for moving the movable core  1320  in response to application of control power is illustrated. At this time, attractive force generated between the fixed core  1310  and the movable core  1320  should be greater than elastic force generated due to compression of a return spring  1130  and the spring  1321 . 
     However, there may be a case in which sufficient attractive force is not generated between the fixed core  1310  and the movable core  1320  due to factors such as a use environment and the like. This results from that moving force of the movable core  1320  depends solely on electromagnetic attractive force between the fixed core  1310  and the movable core  1320 . 
     Therefore, a method for sufficiently securing electromagnetic attractive force generated between the fixed core  1310  and the movable core  1320  is required. 
     Korean Patent Registration No. 10-1216824 discloses a DC relay including a damping magnet. Specifically, the document discloses a DC relay having a damping magnet that is provided below a movable contact to cancel a magnetic flux induced around the movable contact in order to prevent the movable contact from being arbitrarily separated from a fixed contact when the DC relay is in an ON state. 
     However, this type of DC relay has a limitation in that there is no consideration on formation of a magnetic flux for extinguishing arc. That is, the arbitrary separation between the contacts can be prevented, but a method for extinguishing arc generated and a method for securing an extinguishing path are not disclosed. In addition, the document does not suggest a method for securing magnetic force between permanent magnets. 
     Korean Patent Registration No. 10-1661396 discloses a DC relay having a structure capable of maintaining permanent magnets at desired positions. Specifically, the document discloses an electromagnetic relay having a structure capable of maintaining positions of permanent magnets by arranging a first plate member and a second plate member around the permanent magnets to support the permanent magnets. 
     However, this type of electromagnetic relay can maintain the positions of the permanent magnets, but there is a limitation in that any method for changing a direction of a magnetic flux formed by the permanent magnets. 
     Those types of relays also fail to suggest a method for enhancing driving force for moving the movable contact. In addition, polarities of permanent magnets cause inconvenience in that power source and load applied to fixed contacts are limited in specific directions. 
     Korean Patent Registration No. 10-1216824 (Dec. 28, 2012) 
     Korean Patent Registration No. 10-1661396 (Sep. 29, 2016) 
     DISCLOSURE 
     Technical Problem 
     The present disclosure is directed to providing a DC relay having a structure capable of solving those problems and other drawbacks. 
     First, one aspect of the present disclosure is to provide a DC relay having a structure capable of sufficiently reinforcing (enhancing) strength of magnetic fields generated in an inner space. 
     Another aspect of the present disclosure is to provide a DC relay having a structure capable of enhancing strength of magnetic fields without excessively changing arrangement of components. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of generating sufficient magnetic fields without changing positions of permanent magnets provided in an inner space or increasing a size or thickness of the permanent magnets. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of configuring various moving directions of arc extinguished inside the DC relay. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure in which a direction of current applied to a fixed contact is not limited according to polarity of a permanent magnet. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of enhancing driving force for moving a movable contact. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of reducing magnitude of control power applied to move a movable contact. 
     Technical Solution 
     In order to achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided a Direct Current (DC) relay that may include a fixed contactor, a movable contact extending in a longitudinal direction and having one side located adjacent to the fixed contactor to be brought into contact with or separated from the fixed contactor, a plurality of magnet members located adjacent to both end portions of the fixed contactor in the longitudinal direction, respectively, to generate magnetic fields, and a magnetic force reinforcing member located between the plurality of magnet members to form magnetic fields together with the plurality of magnet members. 
     The magnetic force reinforcing member of the DC relay may be located on another side of the fixed contactor opposite to the one side of the fixed contactor. 
     The fixed contactor of the DC relay may include a first fixed contactor biased toward one side from a center of the fixed contactor in the longitudinal direction, and a second fixed contactor biased toward another side opposite to the one side from the center of the fixed contactor in the longitudinal direction. 
     The magnetic force reinforcing member of the DC relay may be located between the first fixed contactor and the second fixed contactor in the longitudinal direction of the fixed contactor. 
     One of the first fixed contactor or the second fixed contactor may be electrically connected to an external power supply, and another one of the first fixed contactor and the second fixed contactor may be electrically connected to an external load. 
     The plurality of magnet members of the DC relay may include a first magnet member located adjacent to one end portion of the fixed contactor in the longitudinal direction, and a second magnet member located adjacent to another end portion of the fixed contactor opposite to the one end portion of the fixed contactor in the longitudinal direction. 
     One side of the first magnet member and one side of the second magnet member facing each other may have the same polarity. 
     One side of the magnetic force reinforcing member of the DC relay facing the fixed contactor may have polarity different from that of each one side of the first magnet member and the second magnet member. 
     Directions of the magnetic fields generated by the first magnet member, the second magnet member, and the magnetic force reinforcing member of the DC relay may be one of a first direction from the first magnet member and the second magnet member toward the magnetic force reinforcing member, and a second direction from the magnetic force reinforcing member toward the first magnet member and the second magnet member. 
     According to another implementation of the present disclosure, there is provided a Direct Current (DC) relay that may include a fixed contactor, a fixed contactor having one side to be brought into contact with or separated from the fixed contactor, a fixed core located at another side opposite to the one side of the fixed contactor to be magnetized when control power is applied, a movable core located at another side of the fixed core opposite to the one side of the fixed core adjacent to the fixed contactor, so as to be moved toward the fixed core when the control power is applied, and a magnetic force reinforcing member located between the fixed contactor and the fixed core to apply attractive force to the movable core in a direction toward the fixed core. 
     The direct current relay may further include coils disposed to surround the fixed core and the movable core to generate an electromagnetic field when the control power is applied, and the fixed core may be magnetized by the electromagnetic field generated by the coils. 
     The fixed core may apply attractive force to the movable core in a direction toward the fixed core when the fixed core is magnetized, and the magnetic force reinforcing member may apply attractive force to the movable core in a direction toward the magnetic force reinforcing member. 
     According to still another implementation of the present disclosure, there is provided a Direct Current (DC) relay that may include a fixed contactor, a fixed contactor having one side located adjacent to the fixed contactor to be brought into contact with or separated from the fixed contactor so as to be electrically connected to or disconnected from the fixed contactor, a shaft extending in a longitudinal direction, and connected to the fixed contactor so as to be movable toward or away from the fixed contactor together with the fixed contactor, a fixed core located adjacent to another side of the fixed contactor opposite to the one side of the fixed contactor, having the shaft inserted therethrough, and magnetized when control power is applied, a movable core located at another side of the fixed core opposite to the one side of the fixed core adjacent to the fixed contactor to be moved toward the fixed core when the control power is applied, and connected with the shaft, and a magnetic force reinforcing member located between the fixed core and the fixed contactor, having the shaft movably coupled therethrough, and configured to apply attractive force to the movable core. 
     The direct current relay may further include a plurality of magnet members located adjacent to both end portions of the fixed contactor in the longitudinal direction, respectively, to generate magnetic fields therebetween, and the magnetic force reinforcing member may generate magnetic fields together with the plurality of magnet members. 
     One side of each of the plurality of magnet members facing each other may have the same polarity, and one side of the magnetic force reinforcing member facing the fixed contactor may have a different polarity from that of the one side of each of the plurality of magnet members. 
     The magnetic force reinforcing member may have a cylindrical shape extending in the longitudinal direction. A hollow portion may be formed through a center of the magnetic force reinforcing member in the longitudinal direction, and the shaft may be coupled through the hollow portion. 
     Advantageous Effects 
     According to the present disclosure, the following effects can be achieved. 
     First, a magnetic force reinforcing member provided between permanent magnets may reinforce magnetic fields generated by the permanent magnets. 
     Accordingly, the magnetic fields generated inside the DC relay can be sufficiently reinforced. 
     The magnetic force reinforcing member may be fitted through a shaft. The magnetic force reinforcing member fitted through the shaft may be located above a fixed core. 
     This may allow the magnetic force reinforcing member to be simply coupled. In addition, the magnetic force reinforcing member for intensifying strength of the magnetic fields can be provided without excessively changing an internal structure of the DC relay. 
     The magnetic force reinforcing member can reinforce the magnetic fields generated by the permanent magnets. That is, the magnetic force reinforcing member may be located to generate a magnetic field in the same direction as the magnetic fields generated by the permanent magnets. 
     Therefore, the magnetic fields can be sufficiently generated without changing positions of the permanent magnets or increasing a size or thickness of the permanent magnets to increase the magnetic forces of the permanent magnets. 
     In addition, the magnetic fields may be generated inside the DC relay in a direction toward or away from the magnetic force reinforcing member, other than a direction from one of the permanent magnets to the other. That is, directions of magnetic fields generated around fixed contacts, respectively, may be different from each other. 
     Accordingly, the magnetic fields can be generated in various directions inside the DC relay, and thus arc extinguishing directions can also be diversified. 
     In addition, the magnetic fields may be generated inside the DC relay in a direction to converge on the magnetic force reinforcing member or a direction to be discharged from the magnetic force reinforcing member. Therefore, based on each fixed contact, arc can receive electromagnetic forces in the same direction. 
     Even if a direction of current applied to the fixed contact is changed, arc can be induced to be extinguished in the same direction. Thus, since the user does not need to connect the DC relay according to polarities, user convenience can be improved. 
     The magnetic force reinforcing member may be located adjacent to the fixed core. When the fixed core is magnetized by an electromagnetic field generated as current flows on coils, the magnetic force reinforcing member can also apply attractive force to the movable core. 
     Therefore, compared to the case where the movable core receives attractive force only by the fixed core, the attractive force applied to the movable core can be increased. As a result, the movable core and the fixed contactor connected to the movable core can be moved smoothly when control power is applied. 
     In addition, even when control power of the same magnitude is applied, the attractive force applied to the movable core by the magnetic force reinforcing member can be increased. 
     Therefore, even if the magnitude of the control power for moving the movable core is decreased, the movable core can be moved smoothly, and thus a quantity of power required for driving the DC relay can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a planar view (a) and a cutout view (b) illustrating a structure of a DC relay according to the related art. 
         FIG. 2  is a planar view (a) and a cross-sectional view (b) illustrating a formation direction of magnetic field and a movement direction of arc when current is applied to the DC relay according to the related art. 
         FIG. 3  is a cross-sectional view illustrating a magnetic path (circuit) formed in the DC relay according to the related art. 
         FIG. 4  is a perspective view of a DC relay in accordance with an implementation of the present disclosure. 
         FIG. 5  is a cross-sectional view of the DC relay of  FIG. 4 . 
         FIG. 6  is a perspective view illustrating a magnetic field reinforcing member provided in the DC relay of  FIG. 4 . 
         FIG. 7  is a perspective view illustrating a state in which the magnetic force reinforcing member provided in the DC relay of  FIG. 4  is coupled to a shaft. 
         FIG. 8  is a planar view in an open state of an upper frame of the DC relay of  FIG. 4 , which illustrates (a) a case where an S pole is formed at an upper side of the magnetic force reinforcing member and (b) a case where an N pole is formed at a lower side of the magnetic force reinforcing member. 
         FIG. 9  is a cutout view illustrating a state in which current flows in the DC relay of  FIG. 4 . 
         FIG. 10  is a planar view (a) and a cross-sectional view (b) illustrating a direction of a magnetic path formed, in response to the flow of current as illustrated in (a) of  FIG. 9 , when the S pole is formed at the upper side of the magnetic force reinforcing member. 
         FIG. 11  is a planar view (a) and a cross-sectional view (b) illustrating a direction of a magnetic path formed, in response to the flow of current as illustrated in (b) of  FIG. 9 , when the S pole is formed at the upper side of the magnetic force reinforcing member. 
         FIG. 12  is a planar view (a) and a cross-sectional view (b) illustrating a direction of a magnetic path formed, in response to the flow of current as illustrated in (a) of  FIG. 9 , when the N pole is formed at the upper side of the magnetic force reinforcing member. 
         FIG. 13  is a planar view (a) and a cross-sectional view (b) illustrating a direction of a magnetic path formed, in response to the flow of current as illustrated in (b) of  FIG. 9 , when the N pole is formed at the upper side of the magnetic force reinforcing member. 
         FIG. 14  is a planar view illustrating a magnetic path formed by the magnetic force reinforcing member in a core part located in a lower side of the DC relay of  FIG. 4 . 
     
    
    
     BEST MODE FOR CARRYING OUT PREFERRED IMPLEMENTATIONS 
     Hereinafter, a DC relay  10  according to an implementation of the present disclosure will be described in detail with reference to the accompanying drawings. 
     In the following description, descriptions of some components may be omitted to help understanding of the present disclosure. 
     1. Definition of Terms 
     It will be understood that when an element is referred to as being “connected with” another element, the element can be connected with the another element or intervening elements may also be present. 
     In contrast, when an element is referred to as being “directly connected with” another element, there are no intervening elements present. 
     A singular representation used herein may include a plural representation unless it represents a definitely different meaning from the context. 
     The term “magnetize” used in the following description refers to a phenomenon in which an object exhibits magnetism in a magnetic field. 
     The term “polarities” used in the following description refers to different properties belonging to an anode and a cathode of an electrode. In one implementation, the polarities may be classified into an N pole or an S pole. 
     The terms “left”, “right”, “top”, “bottom”, “front” and “rear” used in the following description will be understood based on a coordinate system illustrated in  FIGS. 4 and 5 . 
     2. Description of Configuration of DC Relay  10  According to Implementation 
     Referring to  FIGS. 4 and 5 , a DC relay  10  according to an implementation of the present disclosure may include a frame part (or frame unit)  100 , an opening/closing part  300 , a core part  400 , and a movable contactor part  400 . 
     In addition, the DC relay  10  according to the implementation of the present disclosure may include a magnetic force generating part (or magnetism forming unit)  500  for forming a path for extinguishing generated arc and increasing driving force for the movable core  320 . 
     Hereinafter, the DC relay  10  according to the implementation of the present disclosure will be described with reference to  FIGS. 4 and 5 , and the magnetic force generating part  500  will be described as a separate clause. 
     (1) Description of Frame Part  100   
     The frame part (or frame unit)  100  may define appearance of the DC relay  10 . A predetermined space may be defined inside the frame part  100 . Various devices for the DC relay  10  to perform functions for applying or cutting off current may be accommodated in the space. That is, the frame part  100  may function as a kind of housing. 
     The frame part  100  may be formed of an insulating material such as synthetic resin. This may prevent inside and outside of the frame part  100  from being arbitrarily electrically connected to each other. 
     The frame part  100  may include an upper frame  110 , a lower frame  120 , an insulating plate  130 , and a supporting plate  140 . 
     The upper frame  110  may define an upper side of the frame part  100 . The opening/closing part  200  and the movable contactor part  400  may be accommodated in an inner space of the upper frame  110 . 
     The upper frame  110  may be coupled to the lower frame  120 . The insulating plate  130  and the supporting plate  140  may be interposed between the upper frame  110  and the lower frame  120 . The insulating plate  130  and the supporting plate  140  may electrically and physically isolate the inner space of the upper frame  110  and an inner space of the lower frame  120  from each other. 
     A fixed contactor  220  of the opening/closing part  200  may be provided on one side of the upper frame  110 , for example, on an upper side of the upper frame  110  in the illustrated implementation. The fixed contactor  220  may be partially exposed to the upper side of the upper frame  110 , to be electrically connected to an external power supply or a load. 
     The lower frame  120  may define a lower side of the frame part  100 . The core part  300  may be accommodated in the inner space of the lower frame  120 . 
     The lower frame  120  may be coupled to the upper frame  110 . The insulating plate  130  and the supporting plate  140  may be interposed between the lower frame  120  and the upper frame  110 . The insulating plate  130  and the supporting plate  140  may electrically and physically isolate the inner space of the lower frame  120  and the inner space of the upper frame  110  from each other. 
     The insulating plate  130  may be located between the upper frame  110  and the lower frame  120 . The insulating plate  130  may allow the magnetizes upper frame  110  and the lower frame  120  to be electrically spaced apart from each other. 
     This may result in preventing arbitrary electric connection between the opening/closing part  200  and the movable contactor part  400  accommodated in the upper frame  110  and the core part  300  accommodated in the lower frame  120 . 
     A through hole (not shown) may be formed through a central portion of the insulating plate  130 . A shaft  440  of the movable contactor part  400  may be coupled through the through hole (not shown) to be movable up and down. 
     The insulating plate  130  may be supported by the supporting plate  140 . 
     The supporting plate  140  may be located between the upper frame  110  and the lower frame  120 . The supporting plate  140  may allow the magnetizes upper frame  110  and the lower frame  120  to be electrically spaced apart from each other. 
     In addition, the support plate  140  may be located on a lower side of the insulating plate  130  to support the insulating plate  130 . 
     For example, the supporting plate  140  may be formed of a magnetic material. In addition, the supporting plate  140  can configure a magnetic circuit together with a yoke  330  of the core part  300 . The magnetic circuit may apply driving force to the movable core  320  of the core part  300  so as to move toward the fixed core  310 . 
     A through hole (not shown) may be formed through a central portion of the supporting plate  140 . The shaft  440  may be coupled through the through hole (not shown) to be movable up and down. 
     Therefore, when the movable core  320  is moved toward or away from the fixed core  310 , the shaft  440  and the movable contactor  430  connected to the shaft  440  may also be moved in the same direction. 
     (2) Description of Opening/Closing Part  200   
     The opening/closing unit  200  may make current applied or cut off to the DC relay  10  according to an operation of the core part  300 . Specifically, the opening/closing part  200  may allow or block an application of current as the fixed contactor  220  and the movable contactor  430  are brought into contact with or separated from each other. 
     The opening/closing part  200  may be accommodated in the upper frame  110 . The opening/closing part  200  may be electrically and physically spaced apart from the core part  300  by the insulating plate  130  and the supporting plate  140 . 
     The opening/closing part  200  may include an arc chamber  210 , a fixed contactor  220 , and a sealing member  230 . Also, as will be described later, a first magnet member  510  and a second magnet member  520  of the magnetic force generating part  500  may be accommodated in the opening/closing part  200 . 
     The plurality of magnets  510  and  520  may generate a magnetic field inside the arc chamber  210  to control shape and discharge path of arc generated. A detailed description thereof will be given later. 
     The arc chamber  210  may be configured to extinguish arc generated as the fixed contactor  220  and the movable contactor  430  are separated from each other. Therefore, the arc chamber  210  may also be referred to as an “extinguishing portion”. 
     The arc chamber  210  may hermetically accommodate the fixed contactor  220  and the movable contactor  430 . That is, the fixed contactor  220  and the movable contactor  430  may be completely accommodated in the arc chamber  210 . Accordingly, the arc generated when the fixed contactor  220  and the movable contactor  430  are separated from each other may not arbitrarily leak to the outside of the arc chamber  210 . 
     The arc chamber  210  may be filled with extinguishing gas. The extinguishing gas may extinguish the arc and may be discharged to the outside of the DC relay  10  through a preset path. 
     The arc chamber  210  may be formed of an insulating material. In addition, the arc chamber  210  may be formed of a material having high pressure resistance and high heat resistance. This is because the generated arc is a flow of electrons of high-temperature and high-pressure. In one implementation, the arc chamber  210  may be formed of a ceramic material. 
     A plurality of through holes (not shown) may be formed through an upper side of the arc chamber  210 . The fixed contactor  220  may be coupled through each of the through holes (not shown). In the illustrated implementation, the fixed contactor  220  may be provided by two, namely, a first fixed contactor  220   a  and a second fixed contactor  220   b . Accordingly, the through holes (not shown) formed through the upper side of the arc chamber  210  may also be provided by two. 
     When the fixed contactor  220  is coupled through the through hole (not shown), the through hole (not shown) may be sealed. That is, the fixed contactor  220  may be hermetically coupled to the through hole (not shown). Accordingly, generated arc may not be externally discharged through the through hole (not shown). 
     A lower side of the arc chamber  210  may be open. The insulating plate  130  may come in contact with the lower side of the arc chamber  210 . In addition, the sealing member  230  may come in contact with the lower side of the arc chamber  210 . That is, the lower side of the arc chamber  210  may be sealed by the insulating plate  130  and the sealing member  230 . Accordingly, the arc chamber  210  may be electrically and physically isolated from an outer space of the upper frame  110 . 
     In other words, the arc chamber  210  may be sealed by the insulating plate  130 , the supporting plate  140 , the fixed contactor  220 , the sealing member  230 , and a housing  410  of the movable contactor part  400 . 
     The arc extinguished in the arc chamber  210  may be discharged to the outside of the DC relay  10  through a preset path. 
     The fixed contactor  220  may be brought into contact with or separated from the movable contactor  430 , so as to electrically connect or disconnect the inside and the outside of the DC relay  10 . 
     Specifically, when the fixed contactor  220  is brought into contact with the movable contactor  430 , the inside and the outside of the DC relay  10  may be electrically connected. On the other hand, when the fixed contactor  220  is separated from the movable contactor  430 , the electric connection between the inside and the outside of the DC relay  10  may be released. 
     As the name implies, the fixed contactor  220  does not move. That is, the fixed contactor  220  may be fixedly coupled to the upper frame  110  and the arc chamber  210 . Accordingly, the contact and separation between the fixed contactor  220  and the movable contactor  430  can be implemented by the movement of the movable contactor  430 . 
     One end portion of the fixed contactor  220 , for example, an upper end portion in the illustrated implementation, may be exposed to the outside of the upper frame  110 . A power supply or a load may be electrically connected to the one end portion. 
     The fixed contactor  220  may be provided in plurality. In the illustrated implementation, the fixed contactor  220  may be provided by two including a first fixed contactor  220   a  on a left side and a second fixed contactor  220   b  on a right side. 
     The first fixed contactor  220   a  may be located to be biased to one side from a center of the movable contactor  430  in the longitudinal direction, namely, to the left in the illustrated implementation. Also, the second fixed contactor  220   b  may be located to be biased to another side from the center of the movable contactor  430  in the longitudinal direction, namely, to the right in the illustrated implementation. 
     A power supply may be electrically connected to any one of the first fixed contactor  220   a  and the second fixed contactor  220   b . Also, a load may be electrically connected to another one of the first fixed contactor  220   a  and the second fixed contactor  220   b.    
     The DC relay  10  according to the implementation of the present disclosure may be operated regardless of the polarity of the fixed contactor  220 . That is, a power supply or a load may be electrically connected to any one of the first fixed contactor  220   a  and the second fixed contactor  220   b . This may result from a direction a magnetic field generated inside the arc chamber  210 , and a detailed description thereof will be described later. 
     Another end portion of the fixed contactor  220 , for example, a lower end portion in the illustrated implementation may extend toward the movable contactor  430 . When the movable contactor  430  is moved toward the fixed contactor  220 , namely, upward in the illustrated implementation, the lower end portion of the fixed contactor  220  may be brought into contact with the movable contactor  430 . Accordingly, the outside and the inside of the DC relay  10  can be electrically connected. 
     The lower end portion of the fixed contactor  220  may be located inside the arc chamber  210 . That is, the another end portion of the fixed contactor  220  may also be sealed by the arc chamber  210 . 
     When control power is cut off, the movable contactor  430  may be separated from the fixed contactor  220  by elastic force of a return spring  360 . At this time, as the fixed contactor  220  and the movable contactor  430  are separated from each other, arc may be generated between the fixed contactor  220  and the movable contactor  430 . The generated arc may be extinguished by extinguishing gas inside the arc chamber  210  and discharged to the outside. 
     In this case, a path through which the arc is discharged may be changed according to a direction of a magnetic field generated inside the arc chamber  210  and a direction of current applied through the fixed contactor  220 . A detailed description thereof will be given later. 
     The sealing member  230  may block communication between the arc chamber  210  and an inner space of the upper frame  110 . The sealing member  230  may seal the lower side of the arc chamber  210  together with the insulating plate  130  and the supporting plate  140 . 
     In detail, an upper side of the sealing member  230  may be coupled to the lower side of the arc chamber  210 . A radially inner side of the sealing member  230  may be coupled to an outer circumference of the insulating plate  130 , and a lower side of the sealing member  230  may be coupled to the supporting plate  140 . 
     Accordingly, arc generated in the arc chamber  210  and arc extinguished by the extinguishing gas may not flow into the inner space of the upper frame  110 . 
     In addition, the sealing member  230  may prevent an inner space of a cylinder  370  from communicating with the inner space of the frame part  100 . 
     (3) Description of Core Part  300   
     The core part  300  may allow the movable contactor part  400  to move upward as control power is applied. In addition, when the control power is not applied any more, the core part  300  may allow the movable contactor part  400  to move downward again. 
     The core part  300  may be electrically connected to the outside of the DC relay  10 . The core part  300  may receive control power from the outside through the connection. 
     The movable core  300  may be located below the opening/closing part  200 . The core part  300  may be accommodated in the lower frame  120 . The core part  300  and the opening/closing part  200  may be electrically and physically spaced apart from each other by the insulating plate  130  and the supporting plate  140 . 
     The movable contactor part  400  may be located between the core part  300  and the opening/closing part  200 . The movable contactor part  400  may be moved by driving force applied by the core part  300 . Accordingly, the movable contactor  430  and the fixed contactor  220  may be brought into contact with each other so that the DC relay  10  can be electrically connected. 
     The core part  300  may include a fixed core  310 , a movable core  320 , a yoke  330 , a bobbin  340 , a coil  350 , a return spring  360 , and a cylinder  370 . 
     The fixed core  310  may be magnetized by electromagnetic force generated in the coils  350  so as to generate electromagnetic attractive force. The movable core  320  may be moved toward the fixed core  310  (upward in the illustrated implementation) by the attractive force generated by the fixed core  310 . 
     The fixed core  310  may not move. That is, the fixed core  310  may be fixedly coupled to the supporting plate  140  and the cylinder  370 . 
     The fixed core  310  may be implemented as any member that can be magnetized by electromagnetic force. In one implementation, the fixed core  310  may be implemented as a permanent magnet or an electromagnet. 
     The fixed core  310  may be partially accommodated in an upper space inside the cylinder  370 . Further, an outer circumference of the fixed core  310  may come in contact with an inner circumference of the cylinder  370 . 
     The fixed core  310  may be located between the supporting plate  140  and the movable core  320 . 
     A through hole (not shown) may be formed through a central portion of the fixed core  310 . The shaft  440  may be coupled through the through hole (not shown) to be movable up and down. 
     The fixed core  310  may be spaced apart from the movable core  320  by a predetermined distance. Accordingly, a distance by which the movable core  320  can move toward the fixed core  310  may be limited to the distance between the fixed core  310  and the movable core  320 . Accordingly, the predetermined distance may be defined as a “moving distance of the movable core  320 ”. 
     A recessed portion  311  may be formed in a central portion of the fixed core  310  by a predetermined distance. Specifically, the recessed portion  311  may be recessed by the predetermined distance into one surface of the fixed core  310  facing the supporting plate  140 . 
     A magnetic force reinforcing member (or magnetism strengthening member)  530  of the magnetic force generating part  500  may be accommodated in the recessed portion  311 . Accordingly, recessed distance and shape of the recessed portion  311  may preferably be determined according to height and shape of the magnetic force reinforcing member  530 . 
     The recessed portion  311  may extend radially outward from the through hole (not shown) formed through the central portion of the fixed core  310 . The recessed portion  311  may be formed to have the same central axis as the through hole (not shown). 
     One end portion of the return spring  360 , namely, a lower end portion in the implementation may be brought into contact with the lower side of the fixed core  310 . When the movable core  320  is moved upward as the fixed core  310  is magnetized, the return spring  360  may be compressed and store restoring force. 
     Accordingly, when the magnetization of the fixed core  310  is finished, the movable core  320  may be moved downward again. 
     When control power is applied, the movable core  320  may be moved toward the fixed core  310  by electromagnetic attractive force generated by the fixed core  310 . 
     As the movable core  320  is moved, the shaft  440  coupled to the movable core  320  may be moved toward the fixed core  310 , namely, upward in the illustrated implementation. In addition, as the shaft  440  is moved, the movable contactor part  400  coupled to the shaft  440  may be moved upward. 
     Accordingly, the fixed contactor  220  and the movable contactor  430  may be brought into contact with each other so that the DC relay  10  can be electrically connected to external power supply and load. 
     The movable core  320  may have any shape capable of receiving attractive force by electromagnetic force. In one implementation, the movable core  320  may be formed of a magnetic material or implemented as a permanent magnet or an electromagnet. 
     The movable core  320  may be accommodated inside the cylinder  370 . Also, the movable core  320  may be moved in the longitudinal direction of the cylinder  370  inside the cylinder  370 . 
     Specifically, the movable core  320  may be moved toward the fixed core  310  (upward in the illustrated implementation) and away from the fixed core  310  (downward in the illustrated implementation). 
     The movable core  320  may be coupled to the shaft  440 . The movable core  320  may move integrally with the shaft  440 . When the movable core  320  moves upward or downward, the shaft  440  may also move upward or downward. 
     The movable core  320  may be located below the fixed core  310 . The movable core  320  may be spaced apart from the fixed core  310  by a predetermined distance. The predetermined distance may be defined as the moving distance of the movable core  320 , as aforementioned. 
     A predetermined space may be defined inside the movable core  320 . Specifically, the movable core  320  may extend in a longitudinal (lengthwise) direction, and a hollow portion may be recessed into the movable core  320  in the longitudinal direction by a predetermined distance (depth). 
     The return spring  360  and the shaft  440  coupled through the return spring  360  may be partially accommodated in the hollow portion. 
     Specifically, the hollow portion may accommodate a portion, adjacent to the movable core  320 , of a shaft body portion  441  of the shaft  440 , and a shaft tail portion  443  of the shaft  440 . 
     The yoke  330  may form a magnetic circuit as control power is applied. The magnetic circuit formed by the yoke  330  may control a direction of the electromagnetic field generated by the coils  350 . 
     Accordingly, when control power is applied, the coils  350  may generate an electromagnetic field in a direction in which the movable core  320  moves toward the fixed core  310 . The yoke  330  may be formed of a conductive material capable of allowing electrical connection. 
     The yoke  330  may be accommodated inside the lower frame  120 . The yoke  330  may surround the coils  350 . The coils  350  may be accommodated in the yoke  330  with being spaced apart from an inner circumferential surface of the yoke  330  by a predetermined distance. 
     Also, the bobbin  340  may be accommodated in the yoke  330 . That is, the yoke  330 , the coils  350 , and the bobbin  340  on which the coils  350  are wound may be sequentially located radially inward from an outer circumference of the lower frame  120 . 
     An upper side of the yoke  330  may come in contact with the supporting plate  140 . In addition, the outer circumference of the yoke  330  may come in contact with an inner circumference of the lower frame  120  or may be located to be spaced apart from the inner circumference of the lower frame  120  by a predetermined distance. 
     As will be described later, the DC relay  10  according to the implementation of the present disclosure may include a magnetic force reinforcing member  530 . The magnetic force reinforcing member  530  may strengthen (reinforce, enhance) a magnetic circuit formed by the yoke  330 . A detailed description thereof will be given later. 
     The coils  350  may be wound around the bobbin  340 . The bobbin  340  may be accommodated inside the yoke  330 . 
     The bobbin  340  may include upper and lower portions formed in a flat shape, and a cylindrical pole portion extending in the longitudinal direction to connect the upper and lower portions. That is, the bobbin  34  may have a bobbin shape. 
     An upper portion of the bobbin  340  may come in contact with the lower side of the supporting plate  140 . In addition, a lower portion of the bobbin  340  may be supported by a protrusion protruding from the lower side to the upper side of the lower frame  120 . 
     The coils  350  may be wound around the pole portion of the bobbin  340 . A wound thickness of the coils  350  may be the same as a diameter of the upper and lower portions of the bobbin  340 . 
     A hollow portion may be formed through the pole portion of the bobbin  340  extending in the longitudinal direction. The cylinder  370  may be accommodated in the hollow portion. 
     The pole portion of the bobbin  340  may be disposed to have the same central axis as the fixed core  310 , the movable core  320 , and the shaft  440 . 
     The coils  350  may generate an electromagnetic field as control power is applied. The fixed core  310  may be magnetized by the electromagnetic field generated by the coils  350  and thus apply attractive force to the movable core  320 . 
     The coils  350  may be wound around the bobbin  340 . Specifically, the coils  350  may be wound around the pole portion part of the bobbin  340  and stacked on a radial outside of the pole portion. The coils  350  may be accommodated inside the yoke  330 . 
     When control power is applied, the coils  350  may generate an electromagnetic field. In this case, strength and direction of the electromagnetic field generated by the coils  350  may be controlled by the yoke  330 . The fixed core  310  may be magnetized by the electromagnetic field generated by the coils  350 . 
     When the fixed core  310  is magnetized, the movable core  320  may receive electromagnetic force, namely, attractive force in a direction toward the fixed core  310 . Accordingly, the movable core  320  may be moved toward the fixed core  310 , namely, upward in the illustrated implementation. 
     The return spring  360  may apply driving force for the movable core  320  to be moved away from the fixed core  310  when control power is not applied any more after the movable core  320  is moved to the fixed core  310 . 
     The return spring  360  may be compressed and store restoring force as the movable core  320  is moved toward the fixed core  310 . 
     At this time, the restoring force stored by the return spring  360  may preferably be smaller than the attractive force exerted by the magnetized fixed core  310  to the movable core  320 . Accordingly, while control power is applied, the movable core  320  may not be returned to its original position by the return spring  360 . 
     As will be described later, the DC relay  10  according to the implementation of the present disclosure may include the magnetic force reinforcing member  530 . The magnetic force reinforcing member  530  may apply electromagnetic force to the movable core  320  together with the fixed core  310 . 
     Therefore, in the implementation, the restoring force stored by the return spring  360  may preferably be greater than the attractive force exerted by the magnetic force reinforcing member  530  to the movable core  320 , but smaller than the sum of the attractive force exerted by the magnetized fixed core  310  to the movable core  320  and the attractive force exerted by the magnetic force reinforcing member  530  to the movable core  320 . 
     When control power is not applied any more, only the restoring force by the return spring  360  may be applied to the movable core  320 . Accordingly, the movable core  320  can be moved away from the fixed core  310  to be returned to the original position. 
     The return spring  360  may be provided in any form capable of storing restoring force by being compressed in response to the movement of the movable core  320 . In one implementation, the return spring  360  may be configured as a coil spring. 
     A shaft  440  may be coupled through the return spring  360 . The shaft  440  may move up and down regardless of the return spring  360  in a coupled state to the return spring  360 . That is, the shaft  440  may serve to support the return spring  360 . 
     The return spring  360  may be accommodated in the hollow portion formed through the inside of the movable core  320 . In addition, one end portion of the return spring  360  facing the fixed core  310 , namely, an upper end portion in the illustrated implementation may be supported with coming in contact with a lower surface of the fixed core  310 . 
     In addition, one end portion of the return spring  360  facing the fixed core  31 , namely, an upper end portion in the illustrated implementation may be supported with coming in contact with a lower surface of the magnetic force reinforcing member  530 . 
     The cylinder  370  may accommodate the fixed core  310 , the movable core  320 , and the return spring  360 . Inside the cylinder  370 , the movable core  320  may be moved upward and downward. 
     The cylinder  370  may be located in the hollow portion formed through the pole portion of the bobbin  340 . An upper end portion of the cylinder  370  may come in contact with a lower surface of the supporting plate  140 . In addition, a side surface of the cylinder  370  may come in contact with an inner circumferential surface of the pole portion of the bobbin  340 , and an upper opening of the cylinder  370  may be sealed by the fixed core  310 . A lower surface of the cylinder  370  may come in contact with an inner circumferential surface of the lower frame  120 . 
     The cylinder  370  may accommodate the shaft  440 . Inside the cylinder  370 , the shaft  440  may be moved upward or downward together with the movable core  320 . 
     (4) Description of Movable Contactor Part  400   
     The movable contactor part  400  may include the movable contactor  430  and components for moving the movable contactor  430 . The movable contactor part  400  may allow the DC relay  10  to be electrically connected to external power supply and load. 
     The movable contactor part  400  may be accommodated in the frame part  100 , specifically, in the inner space of the upper frame  110 . In detail, the movable contactor part  400  may be accommodated in the arc chamber  210  within the upper frame  110 . 
     The fixed contactor  220  may be located above the movable contactor part  400 . The movable contactor part  400  may be accommodated in the arc chamber  210  to be movable toward and away from the fixed contactor  220  (i.e., movable up and down in the illustrated implementation). 
     The core part  300  may be located below the movable contactor part  400 . The movable contactor part  400  may be accommodated to be movable toward and away from the fixed contactor  220  (i.e., movable up and down in the illustrated implementation), in response to the movement of the movable core  320 . 
     The movable contactor part  400  may include the movable contactor  430 . The movable contactor  430  may be brought into contact with or separated from the fixed contactor  220  in response to the movement of the movable core  320  of the core part  300 . 
     In the illustrated implementation, the movable contactor part  400  may include a housing  410 , a cover  420 , a movable contactor  430 , a shaft  440 , and an elastic portion  450 . 
     Also, although not illustrated, the movable contactor part  400  may include a yoke (not illustrated) for preventing the movable contactor  430  from being arbitrarily separated from the fixed contactor  220 . The yoke (not illustrated) may cancel the electromagnetic repulsive force generated between the fixed contactor  220  and the movable contactor  430 . 
     The housing  410  may accommodate the movable contactor  430  and the elastic portion  450  elastically supporting the movable contactor  430 . 
     In the illustrated implementation, the housing  410  may be formed such that one side and another side opposite to the one side are open. The movable contactor  430  may be inserted through the openings. 
     In the illustrated implementation, the housing  410  may include a base defining a lower surface, and side surfaces protruding from both ends of the base toward the fixing contacts  220 , respectively. When the movable contactor  430  is inserted, the side surfaces of the housing  410  may surround the movable contactor  430 . 
     The cover  420  may be provided on a top of the housing  410 . The cover  420  may cover an upper surface of the movable contactor  430  accommodated in the housing  410 . 
     The housing  410  and the cover  420  may preferably be formed of an insulating material to prevent unexpected electrical connection. In one implementation, the housing  410  and the cover  420  may be formed of synthetic resin or the like. 
     A bottom of the housing  410  may be connected to the shaft  440 . When the movable core  320  connected to the shaft  440  is moved upward or downward, the housing  410  may also be moved upward or downward. 
     The housing  410  and the cover  420  may be coupled by arbitrary members. In one implementation, the housing  410  and the cover  420  may be coupled by a coupling member (not illustrated) such as a bolt and a nut. 
     In this case, the cover  420  may be fitted to the housing  410 . To this end, grooves (not illustrated) may be recessed in upper end portions of the both side surfaces of the housing  410 , and protrusions (not illustrated) to be inserted into the grooves may be formed on the cover  420 . 
     The movable contactor  430  may come in contact with the fixed contactor  220  when control power is applied, so that the DC relay  10  can be electrically connected to external power supply and load. When control power is not applied, the movable contactor  430  may be separated from the fixed contactor  220  such that the DC relay  10  can be electrically disconnected from the external power supply and load. 
     The movable contactor  430  may be located adjacent to the fixed contactor  220 . 
     An upper side of the movable contactor  430  may be covered by the cover  420 . In one implementation, the upper side of the movable contactor  430  may come in contact with one surface of the cover  420  facing the movable contactor  430 , namely, a lower surface in the illustrated implementation. 
     A lower side of the movable contactor  430  may be elastically supported by the elastic portion  450 . In order to prevent the movable contactor  430  from being arbitrarily moved downward, the elastic portion  450  may elastically support the movable contactor  430  in a restored state to some extent after being compressed. 
     Accordingly, when the elastic portion  450  applies elastic force to the movable contactor  430  in a direction toward the cover  420 , the movable contactor  430  may be stably maintained in a contact state with the fixed contactor  220 . 
     The movable contactor  430  may extend in the longitudinal direction, namely, in left and right directions in the illustrated implementation. That is, a length of the movable contactor  430  may be longer than its width. 
     Accordingly, when the movable contactor  430  is accommodated in an inner space of the housing  410 , both end portions of the movable contactor  430  in the longitudinal direction may be exposed to the outside of the housing  410 . Contact protrusions  431  may protrude from the both end portions. 
     The contact protrusions  431  of the movable contactor  430  may be portions brought into contact with the fixed contactor  220 . The contact protrusions  431  may protrude by a predetermined distance from one surface of the movable contactor  430  facing the fixed contactor  220 , namely, from an upper surface in the illustrated implementation. 
     In the illustrated implementation, the fixed contactor  220  may include a first fixed contactor  220   a  on a left side and a second fixed contactor  220   b  on a right side. Accordingly, the contact protrusions  431  may be formed on end portions of the movable contactor  430  corresponding to positions of the respect fixed contacts  220 . 
     The contact protrusions  431  can reduce a distance by which the movable contactor  430  has to be moved to come into contact with the fixed contactor  220 . 
     Other portions of the movable contactor  430 , except for the contact protrusions  431 , may not come into contact with the fixed contactor  220 . Since the contact protrusions  431  protrude from the movable contactor  430 , the contact protrusions  431  of the movable contactor  430  may be portions closest to the fixed contactor  220 . 
     A width of the movable contactor  430  may be the same as a spaced distance between the side surfaces of the housing  410 . That is, when the movable contactor  430  is accommodated in the housing  410 , both side surfaces of the movable contactor  430  in a width direction may be brought into contact with inner sides of the side surfaces of the housing  410 . 
     Accordingly, the state where the movable contactor  430  is accommodated in the housing  410  can be stably maintained. 
     The shaft  440  may transmit driving force, which is generated in response to the operation of the core part  300 , to the movable contactor part  400 . Specifically, the shaft  440  may be connected to the movable core  320  and the movable contactor  430 . When the movable core  320  is moved upward or downward, the movable contactor  430  may be moved upward or downward. 
     The shaft  440  may extend in the longitudinal direction, namely, in the up and down (vertical) direction in the illustrated implementation. 
     The shaft  440  may be coupled to the movable core  320 . When the movable core  320  is moved up and down, the shaft  440  may also be moved up and down together with the movable core  320 . 
     The shaft  440  may be coupled to the housing  410 . When the shaft  440  is moved up and down, the housing  410  may also be moved up and down together with the shaft  440 . 
     The shaft  440  may be coupled through the fixed core  310  and the magnetic force reinforcing member  530  to be movable up and down. The shaft  440  may be inserted into the movable core  320 . In addition, the return spring  360  may be fitted through the shaft  440 . 
     The shaft  440  may include a shaft body portion  441 , a shaft head portion  442 , and a shaft tail portion  443 . 
     The shaft body portion  441  may define the body of the shaft  440 . In the illustrated implementation, the support body portion  441  may be formed in a cylindrical shape having a circular cross section and extending in the longitudinal direction. 
     The shaft head portion  442  may be located on one end portion of the shaft body portion  441  coupled to the housing  410 , namely, on an upper end portion in the illustrated implementation. The shaft head portion  442  may be coupled to the housing  410 . The shaft head portion  442  may be formed to have a larger diameter than the shaft body portion  441 . 
     The shaft head portion  442  and the housing  410  may be integrally formed with each other. In one implementation, the shaft head portion  442  and the housing  410  may be formed through insert-injection molding. 
     The shaft tail portion  443  may be located on one end portion of the shaft body portion  441  inserted into the movable core  320 , namely, on a lower end portion in the illustrated implementation. The shaft tail portion  443  may be coupled to the movable core  320 . The shaft tail portion  443  may be formed to have a larger diameter than the shaft body portion  441 . 
     The coupled states between the shaft  440  and the housing  410  and between the shaft  440  and the movable core  320  can be stably maintained by the shaft head portion  442  and the shaft tail portion  443 . 
     The elastic portion  450  may elastically support the movable contactor  430 . When the movable contactor  430  comes into contact with the fixed contactor  220 , the movable contactor  430  may tend to be separated from the fixed contactor  220  by electromagnetic repulsive force. 
     At this time, the elastic portion  450  may elastically support the movable contactor  430  to prevent the movable contactor  430  from being arbitrarily separated from the fixed contactor  220 . 
     The elastic portion  450  may be formed in any shape capable of being compressed or stretched to store restoring force and transmitting the stored restoring force to another member. In one implementation, the elastic portion  450  may be configured as a coil spring. 
     One end portion of the elastic portion  450  facing the movable contactor  430 , namely, an upper end portion in the illustrated implementation, may come in contact with the lower side of the movable contactor  430 . In addition, another end portion of the elastic portion  450  opposite to the one end portion, namely, an upper side of the housing  410  may come in contact with the upper side of the housing  410 . 
     The elastic portion  450  may elastically support the movable contactor  430  in a state of storing the restoring force by being compressed by a predetermined length. Accordingly, even if electromagnetic repulsive force is generated between the movable contactor  430  and the fixed contactor  220 , the movable contactor  430  and the fixed contact  430  may not be separated from each other by the elastic portion  450 . 
     A protrusion (not illustrated) to which the elastic portion  450  can be fitted may protrude from the lower side of the movable contactor  430  to enable stable coupling of the elastic portion  450 . Similarly, a protrusion (not illustrated) to which the elastic portion  450  can be fitted may protrude from the top of the housing  410 . 
     3. Description of Magnetic Force Generating Part  500  Provided in DC Relay  10  According to Implementation 
     Referring back to  FIG. 5 , the DC relay  10  according to the implementation may include a magnetic force generating part (or magnetism forming unit)  500 . 
     The magnetic force generating part  500  may generate a magnetic field for forming a movement path of arc generated inside the arc chamber  210 . In addition, the magnetic force generating part  500  may increase driving force for moving the movable core  320  toward the fixed core  310  as control power is applied. 
     Hereinafter, the magnetic force generating part  500  provided in the DC relay  10  according to the implementation will be described with reference to  FIGS. 5 to 9 . 
     In the illustrated implementation, the magnetic force generating part  500  may include a first magnet member  510 , a second magnet member  520 , and a magnetic force reinforcing member  530 . 
     The first magnet member  510  may generate a magnetic field that forms a path for extinguishing arc generated inside the arc chamber  210 . 
     Specifically, arc may be generated when the fixed contactor  220  and the movable contactor  430  are separated from each other after current can flow in response to the movable contactor  430  being in contact with the fixed contactor  220 . 
     In this case, the first magnet member  510  may generate a magnetic field in the arc chamber  210 . The magnetic field generated by the first magnet member  510  and the current may generate electromagnetic force for guiding the arc. A direction of the electromagnetic force may be defined by the Fleming&#39;s left-hand rule. 
     In the illustrated implementation, the first magnet member  510  may be accommodated in the upper frame  110 . In addition, the first magnet member  510  may be located at the left side outside the arc chamber  210 . This may prevent the first magnet member  510  from being damaged due to the arc generated inside the arc chamber  210 . 
     Also, the first magnet member  510  may come in contact with a left inner surface of the upper frame  110 . The first magnet member  510  may be fixed to the inner surface of the upper frame  110 . To this end, a fixing member (not illustrated) for fixing the first magnet member  510  may be provided. 
     In other words, the first magnet member  510  may be located adjacent to one end portion of the movable contactor  430  in the longitudinal direction, namely, a left end portion in the illustrated implementation. 
     The first magnet member  510  may be formed in any shape capable of generating a magnetic field. In one implementation, the first magnet member  510  may be implemented as a permanent magnet. 
     The magnetic field generated by the first magnet member  510  may be reinforced by the second magnet member  520  and the magnetic force reinforcing member  530 . 
     Further referring to  FIG. 10 , the first magnet member  510  may include a first inner portion  511  and a first outer portion  512 . 
     The first inner portion  511  may be defined as one side of the first magnet member  510  facing the fixed contactor  220 . That is, if it is defined that the fixed contactor  220  is located at an inner side and the upper frame  110  is located at an outer side, the first inner portion  511  may be a portion of the first magnet member  510  facing the inner side. 
     One surface of the first inner portion  511  that is the closest to the fixed contactor  220  may be defined as a first inner surface  511   a.    
     The first outer portion  512  may be defined as one side of the first magnet member  510  facing the inner surface of the upper frame  110 . In other words, the first outer portion  512  may be defined as a portion of the first magnet member  510  opposite to the first inner portion  511 . 
     One surface of the first outer portion  512  that is the closest to the inner surface of the upper frame  110  may be defined as a first outer surface  512   a.    
     The first inner portion  511  and the first outer portion  512  may have different polarities. That is, when the first inner portion  511  has an N pole, the first outer portion  512  may have an S pole. On the other hand, when the first inner portion  511  has an S pole, the first outer portion  512  may have an N pole. 
     The second magnet member  520  may generate a magnetic field that forms a path for extinguishing arc generated inside the arc chamber  210 . 
     Specifically, arc may be generated when the fixed contactor  220  and the movable contactor  430  are separated from each other after current flows in response to the movable contactor  430  being in contact with the fixed contactor  220 . 
     In this case, the second magnet member  520  may generate a magnetic field in the arc chamber  210 . The magnetic field generated by the second magnet member  520  and the current may generate electromagnetic force for guiding the arc. A direction of the electromagnetic force may be defined by the Fleming&#39;s left-hand rule. 
     In the illustrated implementation, the second magnet member  520  may be accommodated in the upper frame  110 . In addition, the second magnet member  520  may be located at the right side outside the arc chamber  210 . This may prevent the second magnet member  520  from being damaged due to the arc generated inside the arc chamber  210 . 
     Also, the second magnet member  520  may come in contact with a right inner surface of the upper frame  110 . The second magnet member  520  may be fixed to the inner surface of the upper frame  110 . To this end, a fixing member (not illustrated) for fixing the second magnet member  520  may be provided. 
     In other words, the second magnet member  520  may be located adjacent to one end portion of the movable contactor  430  in the longitudinal direction, namely, a right end portion in the illustrated implementation. 
     The second magnet member  520  may be formed in any shape capable of generating a magnetic field. In one implementation, the second magnet member  520  may be implemented as a permanent magnet. 
     The magnetic field generated by the second magnet member  520  may be reinforced by the first magnet member  510  and the magnetic force reinforcing member  530 . 
     Further referring to  FIG. 10 , the second magnet member  520  may include a second inner portion  521  and a second outer portion  522 . 
     The second inner portion  521  may be defined as one side of the second magnet member  520  facing the fixed contactor  220 . That is, if it is defined that the fixed contactor  220  is located at an inner side and the upper frame  110  is located at an outer side, the second inner portion  521  may be a portion of the second magnet member  520  facing the inner side. 
     One surface of the second inner portion  521  that is the closest to the fixed contactor  220  may be defined as a second inner surface  521   a.    
     The second outer portion  522  may be defined as one side of the second magnet member  520  facing the inner surface of the upper frame  110 . In other words, the second outer portion  522  may be defined as a portion of the second magnet member  520  opposite to the second inner portion  521 . 
     One surface of the second outer portion  522  that is the closest to the inner surface of the upper frame  110  may be defined as a second outer surface  522   a.    
     The second inner portion  521  and the second outer portion  522  may have different polarities. That is, when the second inner portion  521  has an N pole, the second outer portion  522  may have an S pole. On the other hand, when the second inner portion  521  has an S pole, the second outer portion  522  may have an N pole. 
     The first magnet member  510  and the second magnet member  520  may be spaced apart from each other with the arc chamber  210  interposed therebetween. The first inner portion  511  of the first magnet member  510  and the second inner portion  521  of the second magnet member  520  may be disposed to face each other. 
     The first inner portion  511  of the first magnet member  510  and the second inner portion  521  of the second magnet member  520  may have the same polarity. Likewise, the first outer portion  512  of the first magnet member  510  and the second outer portion  522  of the second magnet member  520  may have the same polarity. 
     In addition, the first inner portion  511  of the first magnet member  510  and the second inner portion  521  of the second magnet member  520  may have a different polarity from polarity of a first portion  531  of the magnetic force reinforcing member  530 . 
     With the configuration, magnetic fields emitted from the first magnet member  510  and the second magnet member  520  may converge on the magnetic force reinforcing member  530 . On the other hand, a magnetic field emitted from the magnetic force reinforcing member  530  may converge on the first magnet member  510  and the second magnet member  520 . A detailed description thereof will be given later. 
     In the illustrated implementation, the first magnet member  510  and the second magnet member  520  may have a rectangular shape that has a rectangular cross section and extends in the longitudinal direction, namely, in the back and forth direction in the illustrated implementation. The first magnet member  510  and the second magnet member  520  may be formed in any shape capable of generating magnetic fields. 
     In addition, although not illustrated, additional magnet members for generating magnetic fields in the arc chamber  210  may be provided. The additional magnet members (not illustrated) may be provided at the front and the rear outside the arc chamber  210  to generate the magnetic fields. 
     The magnetic force reinforcing member  530  may reinforce the magnetic fields generated by the first magnet member  510  and the second magnet member  520 . Accordingly, the electromagnetic forces generated by the current, which can flow in response to the electric connection between the fixed contactor  220  and the movable contactor  430 , and the magnetic fields can be reinforced, thereby effectively forming an arc extinguishing path. 
     In addition, the magnetic force reinforcing member  530  may control a direction of the magnetic fields generated by the first magnet member  510  and the second magnet member  520 . Accordingly, an external power supply and an external load can be arbitrarily electrically connected to the fixed contactor  220  without the need to maintain directionality. 
     That is, the power supply may be electrically connected to one of the first fixed contactor  220   a  and the second fixed contactor  220   b  and the load may be electrically connected to the other. 
     Furthermore, the magnetic force reinforcing member  530  may reinforce driving force for moving the movable core  320 , which is generated as control power is applied to the core part  300 . Accordingly, even when control power of a smaller magnitude is applied, a driving force sufficient to move the movable core  320  can be secured. 
     The magnetic force reinforcing member  530  may generate a magnetic field in the arc chamber  210 . In addition, the magnetic force reinforcing member  530  may apply electromagnetic attractive force to the movable core  320 . 
     The magnetic force reinforcing member  530  may be located below the lower side of the movable contactor part  400 . Specifically, the magnetic force reinforcing member  530  may be located at the lower side of the housing  410  with being spaced apart from the housing  410  by a predetermined distance. 
     In other words, the magnetic force reinforcing member  530  may be located at another side opposite to one side of the movable contactor  430  adjacent to the fixed contactor  220 . 
     Also, the magnetic force reinforcing member  530  may be located at the center of the movable contactor  430  in the longitudinal direction. As described above, the first fixed contactor  220   a  and the second fixed contactor  220   b  may be located to be biased from the center of the movable contactor  430  in the longitudinal direction of the movable contactor  430 . Therefore, it may be said that the magnetic force reinforcing member  530  is located between the first fixed contactor  220   a  and the second fixed contactor  220   b.    
     The magnetic force reinforcing member  530  may be inserted into the fixed core  310 . Specifically, the magnetic force reinforcing member  530  may be inserted and seated in the recessed portion  311  of the fixed core  310 . 
     The shaft  440  may be coupled through the magnetic force reinforcing member  530 . The shaft  440  may be moved up and down while being coupled through the magnetic force reinforcing member  530 . In this case, the magnetic force reinforcing member  530  may be maintained in an inserted state in the fixed core  310 , irrespective of the movement of the shaft  440 . 
     In the illustrated implementation, the magnetic force reinforcing member  530  may have a cylindrical shape with a hollow portion  535  formed therethrough in a height direction. The magnetic force reinforcing member  530  may be formed in any shape that is coupled to the fixed core  310  so as to reinforce magnetic fields and reinforce driving forces, as described above. 
     The magnetic force reinforcing member  530  may be formed in any shape capable of generating magnetic field and magnetic force. In one implementation, the magnetic force reinforcing member  530  may be implemented as a permanent magnet. 
     The magnetic force reinforcing member  530  may include a first portion  531 , a second portion  532 , an outer circumferential surface  533 , an inner circumferential surface  534 , and a hollow portion  535 . 
     The first portion  531  may define an upper side of the magnetic force reinforcing member  530 . The first portion  531  may be defined as one side of the magnetic force reinforcing member  530  facing the movable contactor  430 . 
     The first portion  531  may have a predetermined polarity. In one implementation, the first portion  531  may have any one of N pole and S pole. 
     The second portion  532  may be located beneath the first portion  531 . The second portion  532  may define a lower side of the magnetic force reinforcing member  530 . The second portion  532  may be defined as one side of the magnetic force reinforcing member  530  facing the fixed core  310  or the movable core  320 . 
     The second portion  532  may have a predetermined polarity. In one implementation, the second portion  532  may have any one of N pole and S pole. 
     The first portion  531  and the second portion  532  may be configured to have opposite polarities. That is, when the first portion  531  has an N pole, the second portion  532  may have an S pole. Conversely, when the first portion  531  has an S pole, the second portion  532  may have an N pole. 
     The first portion  531  may have a polarity opposite to that of the first inner portion  511  of the first magnet member  510  and the second inner portion  521  of the second magnet member  520 . In other words, the second portion  532  may have the same polarity as the first inner portion  511  and the second inner portion  521 . 
     The outer circumferential surface  533  may define a side surface of the magnetic force reinforcing member  530 . In the illustrated implementation, the magnetic force reinforcing member  530  may have a cylindrical shape, and thus the outer circumferential surface  533  may be referred to as a side surface. 
     When the magnetic force reinforcing member  530  is inserted into the recessed portion  311  of the fixed core  310 , the outer circumferential surface  533  may be brought into contact with the inner circumferential surface of the fixed core  310  surrounding the recessed portion  311 . In addition, the outer circumferential surface  533  may be brought into contact with an inner circumferential surface of the supporting plate  140 . 
     Accordingly, the magnetic force reinforcing member  530  can be stably seated on the fixed core  310 . 
     The inner circumferential surface  534  may define an inner surface of the magnetic force reinforcing member  530 . A space surrounded by the inner circumferential surface  534  may be defined as the hollow portion  535 . 
     The hollow portion  535  may be a space formed through the inside of the magnetic force reinforcing member  530  in the height direction. The shaft  440  may be coupled through the hollow portion  535  to be movable up and down. 
     The hollow portion  535  may be defined as a space surrounded by the inner circumferential surface  534 . A diameter of the hollow portion  535  may be slightly larger than a diameter of the shaft body portion  441 . 
     Accordingly, the magnetic force reinforcing member  530  can be maintained in a fixed state regardless of the vertical movement of the shaft  440 . 
     4. Description of Process of Forming Arc Discharge Path in DC Relay  10  According to Implementation 
     The DC relay  10  according to the implementation may generate electromagnetic force for forming an arc discharge path by using flows of magnetic fields and current. 
     The current may be applied in response to the movable contactor  430  being brought into contact with the fixed contactor  220 . In addition, the magnetic fields may be generated by the magnetic force generating part  500 . 
     Hereinafter, a process of forming an arc discharge path in the DC relay  10  according to the implementation will be described in detail with reference to  FIGS. 8 to 13 . 
     In the following description, the first inner portion  511  of the first magnet member  510 , the second inner portion  521  of the second magnet member  520 , and the second portion  532  of the magnetic force reinforcing member  530  may have the same magnetism. 
     In addition, the first outer portion  512 , the second outer portion  522 , and the first portion  531  may have the same magnetism opposite to the above magnetism. 
     As described above, the first magnet member  510  and the second magnet member  520  may be located adjacent to the left inner surface and the right inner surface of the upper frame  110 . In addition, the magnetic force reinforcing member  530  may be located between the first magnet member  510  and the second magnet member  520 . 
     The first fixed contactor  220   a  and the second fixed contactor  220   b  may be located between the first magnet member  510  and the second magnet member  520 . The magnetic force reinforcing member  530  may be located between the first fixed contactor  220   a  and the second fixed contactor  220   b  with the same distance from each fixed contactor  220   a  and  220   b.    
     Similarly, the magnetic force reinforcing member  530  may be located with being spaced apart by the same distance from the first magnet member  510  and the second magnet member  520 . 
     In addition, current carrying (electric connection) conditions may be classified into two types. 
     That is, as illustrated in (a) of  FIG. 9 , a condition may be considered in which current is introduced through the second fixed contactor  220   b  located at the right side, flows through the movable contactor  430 , and is discharged through the first fixed contactor  220   a  located at the left side. Hereinafter, the above condition may be referred to as a “first electric connection (current-carrying) condition”. 
     That is, as illustrated in (b) of  FIG. 9 , a condition may be considered in which current is introduced through the first fixed contactor  220   a  located at the left side, flows through the movable contactor  430 , and is discharged through the second fixed contactor  220   b  located at the right side. Hereinafter, the above condition may be referred to as a “second electric connection condition”. 
     (1) Description of a Process of Forming an Arc Discharge Path when the First Portion  531  of the Magnetic Force Reinforcing Member  530  has an S Pole 
     Hereinafter, a process of forming an arc discharge path when the first portion  531  of the magnetic force reinforcing member  530  has an S pole will be described with reference to (a) of  FIG. 8 , and  FIGS. 9 to 11 . 
     Referring to (a) of  FIG. 8 , an implementation in which an S pole is formed in the first portion  531  of the magnetic force reinforcing member  530  is illustrated. Although not illustrated, an N pole may be formed in the second portion  532  as aforementioned. 
       FIG. 10  illustrates flows (paths) (M.P) of magnetic fields generated in the first electric connection condition and a direction (F 1 ) of electromagnetic forces generated accordingly. 
     In the illustrated implementation, since the first portion  531  has the S pole, the first inner portion  511  and the second inner portion  521  may have the N pole. Considering that the direction of the magnetic field is from the N pole to the S pole, the flows (paths) M.P of the magnetic fields emitted from the first magnet member  510  and the second magnet member  520  may converge to the magnetic force reinforcing member  530  (refer to a first direction A in  FIG. 10 ). 
     In the first electric connection condition, current C.P may be introduced through the second fixed contactor  220   b . When applying the Fleming&#39;s left-hand rule in the vicinity of the second fixed contactor  220   b , the electromagnetic forces may be generated in the direction F 1  (upward in the illustrated implementation). 
     Also, the current C.P may flow out through the first fixed contactor  220   a . When applying the Fleming&#39;s left-hand rule in the vicinity of the first fixed contactor  220   a , the electromagnetic forces may be generated in the direction F 1  (upward in the illustrated implementation). 
       FIG. 11  illustrates flows (paths) (M.P) of magnetic fields generated in the second electric connection condition and a direction F 1  of electromagnetic forces generated accordingly. 
     In the illustrated implementation, since the first portion  531  has the S pole, the first inner portion  511  and the second inner portion  521  may have the N pole. Considering that the direction of the magnetic field is from the N pole to the S pole, the flows (paths) M.P of the magnetic fields emitted from the first magnet member  510  and the second magnet member  520  may converge to the magnetic force reinforcing member  530  (refer to a first direction A in  FIG. 11 ). 
     In the first electric connection condition, the current C.P may be introduced through the first fixed contactor  220   a . When applying the Fleming&#39;s left-hand rule in the vicinity of the first fixed contactor  220   a , the electromagnetic forces may be generated in the direction F 1  (downward in the illustrated implementation). 
     Also, the current C.P may flow out through the second fixed contactor  220   b . When applying the Fleming&#39;s left-hand rule in the vicinity of the second fixed contactor  220   b , the electromagnetic forces may be generated in the direction F 1  (downward in the illustrated implementation). 
     That is, the electromagnetic forces generated in the first fixed contactor  220   a  and the second fixed contactor  220   b  may be applied in the same direction F 1 . Accordingly, compared to the case where the directions of the electromagnetic forces generated in the respective fixed contacts  220   a  and  220   b  are different from each other, arc extinguishing and discharge paths can be effectively formed. 
     This may result from that the paths M.P of the magnetic fields emitted from the first magnet member  510  and the second magnet member  520  proceed toward the magnetic force reinforcing member  530  located therebetween. 
     That is, the paths M.P of the magnetic fields emitted from the first magnet member  510  and the second magnet member  520  may not be biased to any one side. Accordingly, even if the direction of the current in the first fixed contactor  220   a  and the second fixed contactor  220   b  is changed, the electromagnetic forces may be applied in the same direction. 
     (1) Description of a Process of Forming an Arc Discharge Path when the First Portion  531  of the Magnetic Force Reinforcing Member  530  has an N Pole 
     Hereinafter, a process of forming an arc discharge path when the first portion  531  of the magnetic force reinforcing member  530  has an N pole will be described with reference to (b) of  FIG. 8 , and  FIGS. 9, 12, and 13 . 
     Referring to (b) of  FIG. 8 , an implementation in which an N pole is formed in the first portion  531  of the magnetic force reinforcing member  530  is illustrated. Although not illustrated, an S pole may be formed in the second portion  532  as aforementioned. 
       FIG. 12  illustrates flows (paths) (M.P) of magnetic fields generated in the first electric connection condition and a direction F 2  of electromagnetic forces generated accordingly. 
     In the illustrated implementation, since the first portion  531  has the N pole, the first inner portion  511  and the second inner portion  521  may have the S pole. Considering that the direction of the magnetic field is from the N pole to the S pole, the flows (paths) M.P of the magnetic fields emitted from the magnetic force reinforcing member  530  may converge respectively to the first magnet member  510  and the second magnet member  520  (refer to a second direction B in  FIG. 12 ). 
     In the first electric connection condition, current C.P may be introduced through the second fixed contactor  220   b . When applying the Fleming&#39;s left-hand rule in the vicinity of the second fixed contactor  220   b , the electromagnetic forces may be generated in the direction F 2  (downward in the illustrated implementation). 
     Also, the current C.P may flow out through the first fixed contactor  220   a.  When applying the Fleming&#39;s left-hand rule in the vicinity of the first fixed contactor  220   a , the electromagnetic forces may be generated in the direction F 2  (downward in the illustrated implementation). 
       FIG. 13  illustrates flows (paths) (M.P) of magnetic fields generated in the second electric connection condition and a direction F 2  of electromagnetic forces generated accordingly. 
     In the illustrated implementation, since the first portion  531  has the N pole, the first inner portion  511  and the second inner portion  521  may have the S pole. Considering that the direction of the magnetic field is from the N pole to the S pole, the flows (paths) M.P of the magnetic fields emitted from the magnetic force reinforcing member  530  may converge respectively to the first magnet member  510  and the second magnet member  520  (refer to a second direction B in  FIG. 13 ). 
     In the second electric connection condition, the current C.P may be introduced through the first fixed contactor  220   a . When applying the Fleming&#39;s left-hand rule in the vicinity of the first fixed contactor  220   a , the electromagnetic forces may be generated in the direction F 2  (upward in the illustrated implementation). 
     Also, the current C.P may flow out through the second fixed contactor  220   b . When applying the Fleming&#39;s left-hand rule in the vicinity of the second fixed contactor  220   b , the electromagnetic forces may be generated in the direction F 2  (upward in the illustrated implementation). 
     That is, the electromagnetic forces generated in the first fixed contactor  220   a  and the second fixed contactor  220   b  may be applied in the same direction F 2 . Accordingly, compared to the case where the directions of the electromagnetic forces generated in the respective fixed contacts  220   a  and  220   b  are different from each other, arc extinguishing and discharge paths can be effectively formed. 
     This may result from that the paths M.P of the magnetic fields emitted from the magnetic force reinforcing member  530  may proceed toward the first magnet member  510  and the second magnet member  520 . 
     That is, the paths M.P of the magnetic fields emitted from the first magnet member  510  and the second magnet member  520  may not be biased to any one side. Accordingly, even if the direction of the current in the first fixed contactor  220   a  and the second fixed contactor  220   b  is changed, the electromagnetic forces may be applied in the same direction. 
     5. Description of Process of Strengthening Driving Force of Movable Core  320  in DC Relay  10  According to Implementation 
     The DC relay  10  according to the implementation of the present disclosure may generate driving force for moving the movable core  320  toward the fixed core  310 . The driving force may be generated when the fixed core  310  is magnetized by a magnetic field formed by the coils  350  as control power is applied. 
     The DC relay  10  according to the implementation of the present disclosure may include the magnetic force reinforcing member  530 . The magnetic force reinforcing member  530  may reinforce the driving force for moving the movable core  320  toward the fixed core  310 . 
     Hereinafter, a process of strengthening the driving force of the movable core  320  in the DC relay  10  according to the implementation of the present disclosure will be described in detail with reference to  FIG. 14 . 
     As described above, the core part  300  may be electrically connected to an external power supply (not illustrated) to receive control power. When control power is applied, the coils  350  may generate an electromagnetic field. 
     The fixed core  310  may be magnetized by the electromagnetic field generated by the coils  350 . The magnetized fixed core  310  may apply electromagnetic attractive force to the movable core  320  (see solid arrows in  FIG. 14 ). The movable core  320  may be accommodated inside the cylinder  370  to be movable up and down. 
     Accordingly, the movable core  320  may be moved up toward the fixed core  310 . At this time, the return spring  360  may store the restoring force by being compressed, as described above. 
     In this case, the magnetic force reinforcing member  530  may be located in the recessed portion  311  of the fixed core  310 . The magnetic force reinforcing member  530  may be implemented as a permanent magnet capable of generating a magnetic field by itself. That is, the magnetic force reinforcing member  530  may also apply electromagnetic attractive force to the movable core  320  (see dotted arrows in  FIG. 14 ). 
     Accordingly, the movable core  320  may receive the electromagnetic attractive force in a direction toward the fixed core  310  by the magnetized fixed core  310  and the magnetic force reinforcing member  530 . As a result, compared to the case where the movable core  320  is moved only by the electromagnetic attractive force generated by the fixed core  310 , stronger electromagnetic attractive force can be applied to the movable core  320 . 
     The electromagnetic attractive force applied by the magnetized fixed core  310  to the movable core  320  may be proportional to strength of the magnetic field generated by the coils  350 . In addition, the strength of the magnetic field generated by the coils  350  may be proportional to magnitude of control power applied from the outside, for example, magnitude of current or voltage. 
     Accordingly, the magnitude of control power to be applied to the coils  350  to apply the same electromagnetic attractive force to the movable core  320  can be reduced. 
     6. Description of Effects of DC Relay  10  According to Implementation 
     A magnetic force generating part  500  according to an implementation of the present disclosure may include a first magnet member  510  and a second magnet member  520 . In addition, a magnetic force reinforcing member  530  may be located between the first magnet member  510  and the second magnet member  520 . 
     A first inner portion  511  and a second inner portion  521  of the first magnet member  510  and the second magnet member  520  that face each other may have the same polarity. In addition, a first portion  531  of the magnetic force reinforcing member  530  may have different polarity from the first inner portion  511  and the second inner portion  521 . 
     Accordingly, a path M.P of magnetic fields generated by the magnetic force generating part  500  may proceed in a direction from the first magnet member  510  and the second magnet member  520  toward the magnetic force reinforcing member  530 , or vice versa. 
     That is, a distance by which the path M.P of the magnetic fields moves within the arc chamber  210  can be reduced by the magnetic force reinforcing member  530 . This may result in reinforcing the flow M.P of the magnetic fields generated inside the DC relay  10 . 
     In addition, the magnetic force reinforcing member  530  may be coupled through a shaft  440 . The magnetic force reinforcing member  530  may be inserted into a recessed portion  311  which is recessed in an upper side of a fixed core  310 . 
     Accordingly, the magnetic force reinforcing member  530  can be provided without excessively changing an internal structure of the DC relay  10 . 
     In addition, the magnetic force reinforcing member  530  can reinforce paths (flows) M.P of magnetic fields generated by the first magnet member  510  and the second magnet member  520 . 
     Accordingly, the paths M.P of the magnetic fields having sufficient strength can be formed without increasing volumes of the first magnet member  510  and the second magnet member  520 . 
     Also, the paths M.P of the magnetic fields generated in an arc chamber  210  can be formed to proceed from the first magnet member  510  and the second magnet member  520  toward the magnetic force reinforcing member  530 . Alternatively, the paths M.P of the magnetic fields can be formed to proceed from the magnetic force reinforcing member  530  toward the first magnet member  510  and the second magnet member  520 . 
     Accordingly, the flows M.P of the magnetic fields generated in the vicinity of fixed contacts  220   a  and  220   b , respectively, can proceed in different directions. This may facilitate the change in direction for extinguishing arc according to an environment in which the DC relay  10  is provided. This may result in improving user convenience. 
     In addition, the flows M.P of the magnetic fields generated by the first magnet member  510 , the second magnet member  520 , and the magnetic force reinforcing member  530  can generate electromagnetic forces in the same direction near the respective fixed contacts  220   a  and  220   b.    
     Therefore, even if a direction of current applied to each of the fixed contacts  220   a  and  220   b  is changed, arc generated in each of the fixed contacts  220   a  and  220   b  can receive electromagnetic forces all flowing toward any one of the front and the rear of the DC relay  10 . Accordingly, the user does not need to connect a power supply and a load to the DC relay  10  according to polarities, thereby increasing the user convenience. 
     In addition, when current flows on coils  350  and the fixed core  310  is magnetized, the fixed core  310  can apply electromagnetic attractive force to the movable core  320 . At this time, the magnetic force reinforcing member  530  can also apply electromagnetic attractive force to the movable core  320 . 
     Therefore, compared to a case where only electromagnetic attractive force by the fixed core  310  is applied to the movable core  320 , driving force applied to the movable core  320  can be increased. This may result in improving reliability of an operation of the DC relay  10 . 
     Even if magnitude of control power applied to the coils  350  is decreased, electromagnetic attractive force corresponding to the decrease can be compensated for by the magnetic force reinforcing member  530 . Accordingly, magnitude of control power for moving the movable core  320  can be decreased, resulting in improving power efficiency of the DC relay  10 . 
     Although it has been described above with reference to preferred implementations of the present disclosure, it will be understood that those skilled in the art are able to variously modify and change the present disclosure without departing from the spirit and scope of the invention described in the claims below. 
     REFERENCE NUMERALS 
     
         
         
           
               10 : DC relay 
               100 : Frame part 
               110 : Upper frame 
               120 : Lower frame 
               130 : Insulating plate 
               140 : Supporting plate 
               200 : Opening/closing part 
               210 : Arc chamber 
               220 : Fixed contactor 
               220   a : First fixed contactor 
               220   b : Second fixed contactor 
               230 : Sealing member 
               300 : Core part 
               310 ; Fixed core 
               311 : Recessed portion 
               320 : Movable core 
               330 : Yoke 
               340 : Bobbin 
               350 : Coil 
               360 : Return spring 
               370 : Cylinder 
               400 : Movable contactor part 
               410 : Housing 
               420 : Cover 
               430 : Movable contactor 
               431 : Contact protrusion 
               440 : Shaft 
               441 : Shaft body portion 
               442 : Shaft head portion 
               443 : Shaft tail portion 
               450 : Elastic portion 
               500 : Magnetic force generating part 
               510 : First magnet member 
               511 : First inner portion 
               511   a : First inner surface 
               512 : First outer portion 
               512   a : First inner surface 
               520 : Second magnet member 
               521 : Second inner portion 
               521   a : Second inner surface 
               522 : Second outer portion 
               522   a : Second outer surface 
               530 : Magnetic force reinforcing member 
               531 : First portion 
               532 : Second portion 
               533 : Outer circumferential surface 
               534 : Inner circumferential surface 
               535 : Hollow portion 
               1000 : DC relay according to the related art 
               1100 : Contact part according to the related art 
               1110 : Fixed contact according to the related art 
               1120 : Movable contact according to the related art 
               1130 : Return spring according to the related art 
               1200 : Permanent magnet according to the related art 
               1300 : Core part according to the related art 
               1310 : Fixed core according to the related art 
               1320 : Movable core according to the related art 
               1321 : Spring according to the related art 
               1330 : Shaft according to the related art 
               1340 : Bobbin according to the related art 
               1350 : Coil according to the related art 
               1360 : Yoke according to the related art 
             A: First direction 
             B: Second direction 
             F 1 : Direction of electromagnetic force in first electric connection condition 
             F 1 : Direction of electromagnetic force in second electric connection condition 
             M.P: Magnetic path 
             C.P: Current path