Patent Publication Number: US-2022230827-A1

Title: Direct current relay

Description:
FIELD 
     The present disclosure relates to a direct current (DC) relay, and more particularly, to a DC relay having a structure capable of stably maintaining a coupled state of a movable contactor, a housing and an upper yoke for canceling electromagnetic repulsive force between a fixed contactor and the movable contactor. 
     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 generally classified as an electrical circuit switching device. 
     The DC relay may be operated by receiving external control power. The DC relay includes a fixed core and a movable core that can be magnetized by the control power. The fixed core and the movable core are located adjacent to a bobbin on which a plurality of coils are wound. 
     When control power is applied, the plurality of coils generate an electromagnetic field. The fixed core and the movable core are magnetized by the electromagnetic field, and electromagnetic attractive force attractive force is generated between the fixed core and the movable core. 
     Since the fixed core is stationary, the movable core is moved toward the fixed core. One side of a shaft member is connected to the movable core. Further, another side of the shaft member is connected to a movable contactor. 
     When the movable core is moved toward the fixed core, the shaft member and the movable contactor connected to the shaft member are also moved. Responsive to the movement, the movable contactor is moved toward a fixed contactor. When the movable contactor and the fixed contactor are brought into contact with each other, the DC relay is electrically connected to an external power supply and a load. 
     Referring to  FIGS. 1 and 2 , a DC relay  1000  according to the related art includes a frame part  1100 , a contact part  1200 , an actuator  1300 , and a movable contact moving part  1400 . 
     The frame part  1100  may define appearance of the DC relay  1000 . A predetermined space is defined inside the frame part  1100  to accommodate the contact part  1200 , the actuator  1300 , and the movable contact moving part  1400 . 
     When control power is applied from outside, coils  1310  wound around a bobbin  1320  of the actuator  1300  generate an electromagnetic field. A fixed core  1330  and a movable core  1340  are magnetized by the electromagnetic field. Since the fixed core  1330  is stationary, the movable core  1340  and a movable shaft  1350  connected to the movable core  1340  are moved toward the fixed core  1330 . 
     At this time, the movable shaft  1350  is also connected to a movable contact  1220  of the contact part  1200 . Accordingly, by the movement of the movable core  1340 , the movable contact  1220  and a fixed contact  1210  are brought into contact to be electrically connected to each other. 
     When the application of the control power is released, the coils  1310  no longer form the electromagnetic field. Accordingly, electromagnetic attractive force attractive force between the movable core  1340  and the fixed core  1330  disappears. A spring  1360  compressed due to the movement of the movable core  1340  is tensioned, and the movable core  1340 , the movable shaft  1350  connected to the movable core  1340 , and the movable contact  1220  are all moved downward. 
     The movable contact  1220  is coupled to the movable contact moving part  1400 . The movable contact moving part  1400  is moved up and down in response to the movement of the movable core  1340 . 
     The movable contact moving part  1400  includes a movable contact supporting portion  1410  for supporting the movable contact  1220 , and an elastic portion  1430  for elastically supporting the movable contact  1220 . In addition, a movable contact cover portion  1420  is provided on an upper side of the movable contact  1220  to protect the movable contact  1220 . 
     However, in the movable contact moving part  1400  according to the related art, the movable contact  1220  is only elastically supported by the elastic portion  1430 . That is, a separate member for preventing the movable contact  1220  from being separated from the movable contact moving part  1400  is not provided. 
     When the fixed contact  1210  and the movable contact  1220  are in contact with each other, electromagnetic repulsive force is generated as current flows. The repulsive force may be applied to the movable contact  1220  to be separated from the fixed contact  1210 . 
     In this case, even when control power is applied, the DC relay  1000  is not electrically connected, which may cause malfunction or failure. 
     Korean Patent Registration Application No. 10-1216824 discloses a DC relay having a structure that can prevent separation between a movable contact and a fixed contact. Specifically, the patent document discloses a DC relay having a structure in which a separate damping magnet for canceling electromagnetic repulsive force generated between a movable contact and a fixed contact is provided adjacent to a fixed contact. 
     However, this type of DC relay has a limitation in that it includes only a configuration for canceling electromagnetic force. In other words, it is difficult to find a study on countermeasures to prevent the movable contact from being arbitrarily separated from the fixed contact due to incomplete cancellation of the electromagnetic force. 
     Korean Registration Utility Model No. 20-0456811 discloses a DC relay having a structure capable of coupling a permanent magnet located adjacent to a fixed contact in a desired direction. Specifically, the patent document discloses a DC relay having a structure in which a groove is formed in a permanent magnet and a protrusion is formed in a case in which the permanent magnet is accommodated so that the permanent magnet is accommodated only in a direction in which the groove and the protrusion are engaged with each other. 
     However, this type of DC relay also has a limitation in that it includes only a configuration for canceling electromagnetic force. 
     In addition, these types of DC relays have a limitation in that there is no consideration for measures to prevent arbitrary separation of the movable contact while the movable contact moves up and down. 
     Furthermore, these types of DC relays do not suggest a method for simply realizing coupling between the movable contact and members disposed adjacent to the movable contact. 
     Korea Patent Registration No. 10-1216824 (Dec. 28, 2012) 
     Korean Registration Utility Model No. 20-0456811 (Nov. 21, 2011) 
     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 preventing arbitrary separation of a movable contactor even though the movable contactor is moved up and down. 
     Another aspect of the present disclosure is to provide a DC relay having to a structure capable of effectively canceling electromagnetic repulsive force generated between a movable contactor and a fixed contact. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of stably coupling a housing for accommodating a movable contactor with a member for canceling electromagnetic repulsive force generated between the movable contactor and a fixed contactor. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure in which a member for offsetting electromagnetic repulsive force, a member for coupling a housing, and a member for preventing arbitrary separation of a movable contactor can be coupled without a separate coupling member. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of stably maintaining a coupled state of a movable contactor without a separate coupling member. 
     Still another aspect of the present disclosure is to provide a DC relay having a structure capable of coupling a member for preventing arbitrary separation between a movable contactor and a fixed contactor with the movable contactor even without a separate coupling member. 
     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 contactor brought into contact with or separated from the fixed contactor to be electrically connected to or disconnected from the fixed contactor, a housing located on one side of the movable contactor such that one side thereof surrounds the movable contactor, an upper yoke located on another side of the housing opposite to the one side of the housing to surround the housing, and a pin member extending in a longitudinal direction and coupled through the upper yoke and the housing. 
     The pin member of the DC relay may include an outer circumferential portion defining an outer side of the pin member in the longitudinal direction, and a hollow portion formed through an inside of the pin member in the longitudinal direction. The outer circumferential portion of the pin member may include a first end portion constituting one end portion of the outer circumferential portion in a circumferential direction, and a second end portion opposite to the first end portion, spaced apart from the first end portion by a predetermined distance, and constituting another end portion of the outer circumferential portion in the circumferential direction. 
     The distance between the first end portion and the second end portion may be reduced and an outer diameter of the pin member may be reduced accordingly when radially inward pressure is applied to the pin member. 
     An upper yoke through hole may be formed through the upper yoke, and a housing through hole may be formed through the housing. The pin member may be coupled through the upper yoke through hole and the housing through hole, and the upper yoke through hole, the housing through hole, and the pin member may be coaxially disposed. 
     The direct current relay may further include a support member coupled to the movable contactor, the housing, and the upper yoke, and supporting the pin member coupled therethrough. The support member may include a base portion located adjacent to the movable contactor and the housing, and a boss portion protruding from the base portion in a longitudinal direction and located adjacent to the housing and the upper yoke. 
     The boss portion of the DC relay may include therein in a radial direction, a first hollow portion penetratingly formed in a protruding direction of the boss portion, and a second hollow portion communicating with the first hollow portion and surrounded by an inner circumferential surface of the boss portion. An outer circumferential surface of the pin member may be brought into contact with an inner circumferential surface of the boss portion when the pin member is coupled through the second hollow portion. 
     The DC relay may further include a lower yoke located on another side opposite to the one side of the movable contactor to surround the movable contactor. The movable contactor may include a protrusion formed in an annular shape with respect to a central axis of the movable contactor and protruding toward the lower yoke. The lower yoke may include a coupling inner circumferential surface located at a radially outer side of a central axis of the lower yoke to be brought into contact with an outer circumferential surface of the protrusion. 
     In accordance with another implementation, there is provided a Direct Current (DC) relay that may include a fixed contactor, a movable contactor brought into contact with or separated from the fixed contactor to be electrically connected to or disconnected from the fixed contactor, an upper yoke located on one side of the movable contactor such that one side thereof surrounds the movable contactor, a housing located on another side of the upper yoke opposite to the one side of the upper yoke to surround the upper yoke, and a pin member extending in a longitudinal direction and coupled through the housing and the upper yoke. 
     The pin member of the DC relay may include an outer circumferential portion defining an outer side of the pin member in the longitudinal direction, and a hollow portion formed through an inside of the pin member in the longitudinal direction. The outer circumferential portion of the pin member may include a first end portion constituting one end portion of the outer circumferential portion in a circumferential direction, and a second end portion opposite to the first end portion, spaced apart from the first end portion by a predetermined distance, and constituting another end portion of the outer circumferential portion in the circumferential direction. 
     The distance between the first end portion and the second end portion may be reduced and an outer diameter of the pin member may be reduced accordingly when radially inward pressure is applied to the pin member. 
     An upper yoke through hole may be formed through the upper yoke, and a housing through hole may be formed through the housing. The pin member may be coupled through the upper yoke through hole and the housing through hole, and the upper yoke through hole, the housing through hole, and the pin member may be coaxially disposed. 
     The direct current relay may further include a support member coupled to the movable contactor, the housing, and the upper yoke, and supporting the pin member coupled therethrough. The support member may include a base portion located adjacent to the movable contactor and the housing, and a boss portion protruding from the base portion in a longitudinal direction and located adjacent to the housing and the upper yoke. 
     The boss portion of the DC relay may include therein in a radial direction, a first hollow portion penetratingly formed in a protruding direction of the boss portion, and a second hollow portion communicating with the first hollow portion and surrounded by an inner circumferential surface of the boss portion. An outer circumferential surface of the pin member may be brought into contact with an inner circumferential surface\ of the boss portion when the pin member is coupled through the second hollow portion. 
     The DC relay may further include a lower yoke located on another side opposite to the one side of the movable contactor to surround the movable contactor. The movable contactor may include a protrusion formed in an annular shape with respect to a central axis of the movable contactor and protruding toward the lower yoke. The lower yoke may include a coupling inner circumferential surface located at radially outer side of a central axis of the lower yoke to be brought into contact with an outer circumferential surface of the protrusion. 
     Advantageous Effects 
     According to the present disclosure, the following effects can be achieved. 
     First, a pin member may be coupled through a movable contactor. The pin member may be spaced apart from the movable contactor by a predetermined distance. 
     Accordingly, the movable contactor can be moved toward or away from a fixed contactor in a state in which the pin member is coupled through the movable contactor. Also, since the pin member is coupled through the movable contactor to support the movable contactor, arbitrary separation of the movable contactor can be prevented. 
     An upper yoke may be provided on an upper side of the movable contactor. A lower yoke may be provided on a lower side of the movable contactor. When the movable contactor is electrically connected to the fixed contactor, the upper yoke and the lower yoke may be magnetized to generate electromagnetic attractive force therebetween. 
     Accordingly, even if electromagnetic repulsive force is generated between the movable contactor and the fixed contactor, the force may be canceled by the electromagnetic attractive force between the upper yoke and the lower yoke. Therefore, the contact state between the movable contactor and the fixed contactor can be stably maintained. 
     A coupling protrusion may protrude from the lower side of the movable contactor. The coupling protrusion may be inserted into a movable contactor coupling portion recessed in the lower yoke. After the coupling protrusion is inserted into the movable contactor coupling portion, the coupling protrusion may receive radially outward pressure. 
     Accordingly, the coupling protrusion may be expanded and its outer diameter may be increased, so as to be fitted to the movable contactor coupling portion. Therefore, the movable contactor and the lower yoke can be stably coupled to each other. Furthermore, the movable contactor and the lower yoke can be coupled to each other without a separate coupling member. 
     The upper yoke and a housing may be coupled to each other by a support member. The support member may be coupled through the upper yoke and the housing. A base portion formed on a lower side of the support member may be seated on the upper side of the movable contactor. 
     Accordingly, the upper yoke and the housing can be stably coupled to each other. 
     After the support member is coupled through the upper yoke and the housing, the support member may receive radially outward pressure. The support member may be expanded radially outward by the pressure. As the support member is expanded radially outward, an outer circumferential surface of the support member may be fitted to inner circumferential surfaces of the upper yoke and the housing. 
     Accordingly, a separate member for coupling the support member to the upper yoke and the housing may not be required. 
     In addition, before the pin member is coupled through the support member, the pin member may receive radially inward pressure. A cutout portion may be formed in an outer circumferential portion of the pin member, and thus an outer diameter of the pin member may be reduced by the pressure. When the pin member is coupled through the support member, the pressure may be released. 
     Accordingly, the pin member may be expanded radially outward while being restored to its original shape. Thus, the pin member can be fitted to the support member. This may allow the coupling between the pin member and the support member even without a separate coupling member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a DC relay according to the related art. 
         FIG. 2  is a perspective view of a mover assembly provided in the DC relay of  FIG. 1 . 
         FIG. 3  is a perspective view of a DC relay in accordance with one implementation of the present disclosure. 
         FIG. 4  is a cross-sectional view illustrating an inner configuration of the DC relay of  FIG. 3 . 
         FIG. 5  is a perspective view illustrating a movable contactor part provided in a DC relay in accordance with one implementation of the present disclosure. 
         FIG. 6  is an exploded perspective view of the movable contactor part of  FIG. 5 . 
         FIG. 7  is a cross-sectional view illustrating a state (a) before coupling an upper yoke and a housing provided in the movable contactor part of  FIG. 5  and a state (b) after coupling. 
         FIG. 8  is a perspective view illustrating a state in which the upper yoke and the housing provided in the movable contactor part of  FIG. 5  are coupled to each other. 
         FIG. 9  is a cross-sectional view illustrating a state (a) before coupling the upper yoke, the housing, and a shaft body provided in the movable contactor part of  FIG. 5 , and a state (b) after coupling. 
         FIG. 10  is a perspective view illustrating the state (a) before coupling the upper yoke, the housing, and the shaft body provided in the movable contactor part of  FIG. 5 , and the state (b) after coupling. 
         FIG. 11  is a cross-sectional view illustrating a state (a) before coupling a movable contactor and a lower yoke provided in the movable contactor part of  FIG. 5  and a state (b) after coupling. 
         FIG. 12  is a lateral view illustrating a state (a) before coupling the movable contactor, the lower yoke, the upper yoke, the housing, and a shaft provided in the movable contactor part of  FIG. 5 , and a state (b) after coupling. 
         FIG. 13  is a perspective view illustrating states before (a) and after (b) a pin member provided in the movable contactor part of  FIG. 5  is changed in shape due to external pressure. 
         FIG. 14  is a planar view illustrating the states before (a) and after (b) the pin member provided in the movable contactor part of  FIG. 5  is changed in shape due to the external pressure. 
         FIG. 15  is a front cross-sectional view illustrating a state (a) before coupling the movable contactor, the lower yoke, the upper yoke, the housing, the shaft, and the pin member provided in the movable contactor part of  FIG. 5 , and a state (b) after coupling. 
         FIG. 16  is a lateral cross-sectional view illustrating the state (a) before coupling the movable contactor, the lower yoke, the upper yoke, the housing, the shaft, and the pin member provided in the movable contactor part of  FIG. 5 , and the state (b) after coupling. 
         FIG. 17  is a perspective view illustrating the state (a) before coupling the movable contactor, the lower yoke, the upper yoke, the housing, the shaft, and the pin member provided in the movable contactor part of  FIG. 5 , and the state (b) after coupling. 
         FIG. 18  is a flowchart illustrating a method for coupling a movable contactor part in accordance with one implementation of the present disclosure. 
         FIG. 19  is a flowchart illustrating detailed steps of step S 100  of  FIG. 18 . 
         FIG. 20  is a flowchart illustrating detailed steps of step S 200  of  FIG. 18 . 
         FIG. 21  is a flowchart illustrating detailed steps of step S 300  of  FIG. 18 . 
         FIG. 22  is a flowchart illustrating detailed steps of step S 400  of  FIG. 18 . 
         FIG. 23  is a perspective view illustrating a movable contactor part provided in a DC relay in accordance with another implementation of the present disclosure. 
         FIG. 24  is an exploded perspective view of the movable contactor part according to the implementation of  FIG. 23 . 
     
    
    
     BEST MODE FOR CARRYING OUT PREFERRED IMPLEMENTATIONS 
     Hereinafter, a DC relay 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. 
     2. Description of Configuration of DC Relay According to Implementation 
     Referring to  FIGS. 3 and 4 , a DC relay  1  according to an implementation of the present disclosure may include a frame part  10 , an opening/closing part  20 , and a core part  30 . 
     In addition, the DC relay  1  according to the implementation of the present disclosure may further include a movable contactor part  40  having a structure for improving reliability of application and blocking of current. 
     Hereinafter, the DC relay  1  according to the implementation of the present disclosure will be described with reference to  FIGS. 3 and 4  but the movable contactor part  40  will be described as a separate clause. 
     (1) Description of Frame Part  10   
     The frame part  10  may define appearance of the DC relay  1 . A predetermined space may be defined inside the frame part  10 . Various devices for the DC relay  1  to perform functions for applying or cutting off current may be accommodated in the space. That is, the frame part  10  may function as a kind of housing. 
     The frame part  10  may be formed of an insulating material such as synthetic resin. This may prevent inside and outside of the frame part  10  from being arbitrarily electrically connected to each other. 
     The frame part  10  may include an upper frame  11 , a lower frame  12 , an insulating plate  13 , and a supporting plate  14 . 
     The upper frame  11  may define an upper side of the frame part  10 . The opening/closing part  20  and the movable contactor part  40  may be accommodated in an inner space of the upper frame  11 . 
     The upper frame  11  may be coupled to the lower frame  12 . The insulating plate  13  and the supporting plate  14  may be interposed between the upper frame  11  and the lower frame  12 . The insulating plate  13  and the supporting plate  14  may electrically and physically isolate the inner space of the upper frame  11  and an inner space of the lower frame  12  from each other. 
     A fixed contactor  22  of the opening/closing part  20  may be provided on one side of the upper frame  11 , for example, on an upper side of the upper frame  11  in the illustrated implementation. The fixed contactor  22  may be partially exposed to the upper side of the upper frame  11 , to be electrically connected to an external power supply or a load. 
     The lower frame  12  may define a lower side of the frame part  10 . The core part  30  may be accommodated in the inner space of the lower frame  12 . 
     The lower frame  12  may be coupled to the upper frame  11 . The insulating plate  13  and the supporting plate  14  may be interposed between the lower frame  12  and the upper frame  11 . The insulating plate  13  and the supporting plate  14  may electrically and physically isolate the inner space of the lower frame  12  and the inner space of the upper frame  11  from each other. 
     The insulating plate  13  may be located between the upper frame  11  and the lower frame  12 . The insulating plate  13  may allow the upper frame  11  and the lower frame  12  to be electrically spaced apart from each other. 
     This may result in preventing arbitrary electric connection between the opening/closing part  20  and the movable contactor part  40  accommodated in the upper frame  11  and the core part  30  accommodated in the lower frame  12 . 
     A through hole (not shown) may be formed through a central portion of the insulating plate  13 . A shaft  320  of a lower assembly  300  may be coupled through the through hole (not shown) to be movable up and down. 
     The insulating plate  13  may be supported by the supporting plate  14 . 
     The supporting plate  14  may be located between the upper frame  11  and the lower frame  12 . The supporting plate  14  may allow the upper frame  11  and the lower frame  12  to be electrically spaced apart from each other. 
     In addition, the supporting plate  14  may be formed of a magnetic material so as to configure a magnetic circuit together with a yoke  33  of the core part  30 . 
     A through hole (not shown) may be formed through a central portion of the supporting plate  14 . The shaft  320  may be coupled through the through hole (not shown) to be movable up and down. 
     (2) Description of Opening/Closing Part  20   
     The opening/closing unit  20  may make current applied to or cut off from the DC relay  1  according to an operation of the core part  30 . Specifically, the opening/closing part  20  may allow or block an application of current as the fixed contactor  22  and the movable contactor  210  are brought into contact with or separated from each other. 
     The opening/closing part  20  may be accommodated in the upper frame  11 . The opening/closing part  20  may be electrically and physically isolated from the core part  30  by the insulating plate  13  and the supporting plate  14 . 
     The opening/closing part  20  may include an arc chamber  21 , a fixed contactor  22 , and a sealing member  23 . Also, although not shown, the opening/closing part  20  may include a plurality of magnets. The plurality of magnets (not shown) may generate a magnetic field inside the arc chamber  21  to control shape and discharge path of arc generated. 
     The arc chamber  21  may be configured to extinguish arc generated as the fixed contactor  22  and the movable contactor  210  are separated from each other. Therefore, the arc chamber  21  may also be referred to as an “extinguishing portion”. 
     The arc chamber  21  may hermetically accommodate the fixed contactor  22  and the movable contactor  210 . That is, the fixed contactor  22  and the movable contactor  210  may be completely accommodated in the arc chamber  21 . Accordingly, the arc generated when the fixed contactor  22  and the movable contactor  210  are separated from each other may not arbitrarily leak to the outside of the arc chamber  21 . 
     The arc chamber  21  may be filled with extinguishing gas. The extinguishing gas may extinguish the arc and may be discharged to the outside of the DC relay  1  through a preset path. 
     The arc chamber  21  may be formed of an insulating material. In addition, the arc chamber  21  may be formed of a material having high pressure resistance and high heat resistance. In one implementation, the arc chamber  21  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  21 . The fixed contactor  22  may be coupled through each of the through holes (not shown). The fixed contactor  22  may be hermetically coupled to the through hole (not shown). Accordingly, the generated arc cannot be externally discharged through the through hole (not shown). 
     A lower side of the arc chamber  21  may be open. The insulating plate  13  may come in contact with the lower side of the arc chamber  21 . In addition, a sealing member  23  may come in contact with the lower side of the arc chamber  21 . Accordingly, the arc chamber  21  can be electrically and physically isolated from an outer space of the upper frame  11 . 
     As a result, an inside of the arc chamber  21  may be sealed by the insulating plate  13 , the supporting plate  14 , the fixed contactor  22 , the sealing member  23 , and a shaft support member  310  of the movable contactor part  40 . 
     The arc extinguished in the arc chamber  21  may be discharged to the outside of the DC relay  1  through a preset path. 
     The fixed contactor  22  may be brought into contact with or separated from the movable contactor  210 , so as to electrically connect or disconnect the inside and the outside of the DC relay  1 . 
     Specifically, when the fixed contactor  22  is brought into contact with the movable contactor  210 , the inside and the outside of the DC relay  1  may be electrically connected. On the other hand, when the fixed contactor  22  is separated from the movable contactor  210 , the electric connection between the inside and the outside of the DC relay  1  may be released. 
     As the name implies, the fixed contactor  22  does not move. That is, the fixed contactor  22  may be fixedly coupled to the upper frame  11  and the arc chamber  21 . Accordingly, the contact and separation between the fixed contactor  22  and the movable contactor  210  may be implemented by the movement of the movable contactor  210 . 
     One end portion of the fixed contactor  22 , for example, an upper end portion in the illustrated implementation, may be exposed to the outside of the upper frame  11 . A power supply or a load may be electrically connected to the one end portion. 
     The fixed contactor  22  may be provided in plurality. In the illustrated implementation, the fixed contactor  22  may be provided as a pair, i.e., by two. A power supply may be electrically connected to one of the fixed contacts  22 , and a load may be electrically connected to the other fixed contactor  22 . 
     Another end portion of each fixed contactor  22 , for example, a lower end portion in the illustrated implementation may extend toward the movable contactor  210 . When the movable contactor  210  moves upward, the lower end portion of the fixed contactor  22  may be brought into contact with the movable contactor  210 . Accordingly, the outside and the inside of the DC relay  1  can be electrically connected. 
     The another end portion of the fixed contactor  22  may be located inside the arc chamber  21 . That is, the another end portion of the fixed contactor  22  may be sealed by the arc chamber  21 . 
     When control power is cut off, the movable contactor  210  may be separated from the fixed contactor  22  by elastic force of a return spring  36 . At this time, as the fixed contactor  22  and the movable contactor  210  are separated from each other, the arc may be generated between the fixed contactor  22  and the movable contactor  210 . The generated arc may be extinguished by the extinguishing gas inside the arc chamber  21  and discharged to the outside. 
     The sealing member  23  may block communication between the arc chamber  21  and the inside of the upper frame  11 . The sealing member  23  may seal the lower side of the arc chamber  21  together with the supporting plate  14 . 
     Specifically, a lower side of the sealing member  23  may be coupled to the supporting plate  14 . In addition, an upper side of the sealing member  23  may be coupled to the lower side of the arc chamber  21 . 
     Accordingly, arc generated in the arc chamber  21  and arc extinguished by the extinguishing gas may not flow into the inner space of the upper frame  11 . 
     In addition, the sealing member  23  may prevent an inner space of a cylinder  37  from communicating with the inner space of the frame part  10 . 
     (3) Description of Core Part  30   
     The core part  30  may allow the movable contactor part  40  to move upward as control power is applied. In addition, when the control power is not applied any more, the core part  30  may allow the movable contactor part  40  to move downward again. 
     The core part  30  may be electrically connected to the outside of the DC relay  1 . The core part  30  may receive control power from the outside through the connection. 
     The core part  30  may be accommodated in the lower frame  12 . The core part  30  and the opening/closing part  20  may be electrically and physically spaced apart from each other by the insulating plate  13  and the supporting plate  14 . 
     The movable contactor part  40  may be located between the core part  30  and the opening/closing part  20 . The movable contactor part  40  may be moved by moving force applied by the core part  30 . Accordingly, the movable contactor  210  and the fixed contactor  22  may be brought into contact with each other so that the DC relay  1  can be electrically connected. 
     The core part  30  may include a fixed core  31 , a movable core  32 , a yoke  33 , a bobbin  34 , coils  35 , a return spring  36 , and a cylinder  37 . 
     The fixed core  31  may be magnetized by electromagnetic force generated in the coil  35  so as to generate an electromagnetic field. The movable core  32  may receive attractive force by the electromagnetic field generated in the fixed core  31 , and thus move toward the fixed core  31  (toward an upper side in the illustrated implementation). 
     The fixed core  31  may not move. That is, the fixed core  31  may be fixedly coupled to the supporting plate  14  and the cylinder  37 . 
     The fixed core  31  may be implemented as any member that can be magnetized by electromagnetic force. In one implementation, the fixed core  31  may be implemented as a permanent magnet or an electromagnet. 
     The fixed core  31  may be partially accommodated in an upper space inside the cylinder  37 . Further, an outer circumference of the fixed core  31  may come in contact with an inner circumference of the cylinder  37 . 
     The fixed core  31  may be located between the supporting plate  14  and the movable core  32 . 
     A through hole (not shown) may be formed through a central portion of the fixed core  31 . The shaft  320  may be coupled through the through hole (not shown) to be movable up and down. 
     The fixed core  31  may be spaced apart from the movable core  32  by a predetermined distance. The predetermined distance may be a distance at which the movable core  32  can be moved toward the fixed core  31 . Accordingly, the predetermined distance may be defined as a “moving distance of the movable core  32 ”. 
     One end of the return spring  36  may come in contact with a lower side of the fixed core  31 . When the movable core  32  is moved upward as the fixed core  31  is magnetized, the return spring  36  may be compressed. Accordingly, when the magnetization of the fixed core  31  is finished, the movable core  32  may be moved backward again. 
     When control power is applied, the movable core  32  may be moved toward the fixed core  31  by receiving electromagnetic force by the electromagnetic field generated in the fixed core  31 . 
     As the movable core  32  is moved, the shaft  320  coupled to the movable core  32  may be moved upward. In addition, as the shaft  320  is moved, the movable contactor part  40  coupled to the shaft  320  may be moved upward. Accordingly, the fixed contactor  22  and the movable contactor  210  may be brought into contact with each other so that the DC relay  1  can be electrically connected. 
     The movable core  32  may have any shape capable of receiving attractive force by electromagnetic force. In one implementation, the movable core  32  may be implemented as a permanent magnet or an electromagnet. 
     The movable core  32  may be accommodated inside the cylinder  37 . In addition, the movable core  32  may be movable toward the fixed core  31  and away from the fixed core  31 , namely, in the up and down (vertical) direction in the illustrated implementation, within the cylinder  37 . 
     The movable core  32  may be coupled to the shaft  320 . The movable core  32  may move integrally with the shaft  320 . When the movable core  32  moves upward or downward, the shaft  320  may also move upward or downward. 
     The movable core  32  may be located below the fixed core  31 . The movable core  32  may be spaced apart from the fixed core  31  by a predetermined distance. As described above, the predetermined distance may be defined as the moving distance of the movable core  32 . 
     A predetermined space may be defined inside the movable core  32 . Specifically, the movable core  32  may extend in a longitudinal (lengthwise) direction, and include a hollow portion extending in the longitudinal direction inside the movable core  32 . 
     The return spring  36  and the shaft  320  coupled through the return spring  36  may be partially accommodated in the hollow portion. 
     Protrusions  32   a  may protrude radially inward from one side of the hollow portion opposite to the fixed core  31 , namely, from a lower side of the hollow portion in the implementation. One end of the return spring  36 , namely, a lower end in the implementation may be brought into contact with the protrusions  32   a.    
     In addition, a movable core supporting portion  323  formed on a lower side of a shaft body portion  322  of the shaft  320  may come in contact with the protrusions  32   a . Accordingly, when the movable core  32  is moved upward, the shaft  320  may also be moved upward. 
     The yoke  33  may form a magnetic circuit as control power is applied. The magnetic circuit formed by the yoke  33  may control a direction of the electromagnetic field generated by the coils  35 . Accordingly, when control power is applied, the coils  35  may generate an electromagnetic field in a direction in which the movable core  32  moves toward the fixed core  31 . 
     The yoke  33  may be accommodated inside the lower frame  12 . The yoke  33  may surround the coils  35 . The coils  35  may be accommodated in the yoke  33  with being spaced apart from an inner circumferential surface of the yoke  33  by a predetermined distance. 
     Also, the bobbin  44  may be accommodated in the yoke  33 . That is, the yoke  33 , the coils  35 , and the bobbin  34  on which the coils  35  are wound may be sequentially located radially inward from an outer circumference of the lower frame  12 . 
     An upper side of the yoke  33  may come in contact with the supporting plate  14 . In addition, an outer circumference of the yoke  33  may come in contact with an inner circumference of the lower frame  12 . 
     The coils  35  may be wound around the bobbin  34 . The bobbin  34  may be accommodated inside the yoke  33 . 
     The bobbin  34  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  34  may come in contact with the lower side of the supporting plate  14 . In addition, a lower portion of the bobbin  34  may come in contact with an inner circumferential surface of the lower side of the lower frame  12 . 
     The coils  35  may be wound around the pole portion of the bobbin  34 . A wound thickness of the coils  35  may be the same as a diameter of the upper and lower portions of the bobbin  34 . 
     A hollow portion may be formed through the pole portion of the bobbin  34  in the longitudinal direction. The cylinder  37  may be accommodated in the hollow portion. 
     The coils  35  may generate an electromagnetic field as control power is applied. The fixed core  31  may be magnetized by the electromagnetic field generated by the coils  35  and thus apply attractive force to the movable core  32 . 
     The coils  35  may be wound around the bobbin  34 . Specifically, the coils  35  may be wound on the pole portion of the bobbin  34 . The coils  35  may be accommodated inside the yoke  33 . 
     When control power is applied, the coils  35  may generate an electromagnetic field. In this case, a direction of the electromagnetic field generated by the coils  35  may be controlled by the yoke  33 . The fixed core  31  may be magnetized by the electromagnetic field generated by the coils  35 . 
     When the fixed core  31  is magnetized, the movable core  32  may receive electromagnetic force, namely, attractive force in a direction toward the fixed core  31 . Accordingly, the movable core  32  may be moved toward the fixed core  31 , namely, upward in the illustrated implementation. 
     The return spring  36  may provide driving force for the movable core  32  to be moved away from the fixed core  31  when control power is not applied any more after the movable core  32  is moved to the fixed core  31 . 
     The return spring  36  may and store restoring force while being compressed as the movable core  32  is moved toward the fixed core  31 . 
     At this time, the restoring force stored by the return spring  36  may preferably be smaller than the attractive force exerted by the fixed core  31  to the movable core  32 . Accordingly, while control power is applied, the movable core  32  may not be returned to its original position by the return spring  36 . 
     When control power is not applied any more, only the restoring force by the return spring  36  may be exerted to the movable core  32 . Accordingly, the movable core  32  may be moved away from the fixed core  31  to be returned to the original position. 
     The return spring  36  may be provided in any form capable of storing restoring force by being compressed in response to the movement of the movable core  32 . In one implementation, the return spring  36  may be configured as a coil spring. 
     A shaft  320  may be coupled through the return spring  36 . The shaft  320  may move up and down regardless of the return spring  36  in a coupled state to the return spring  36 . 
     The return spring  36  may be accommodated in the hollow portion formed through the inside of the movable core  32 . In addition, one end portion of the return spring  36  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 fixed core  31 . 
     Another end portion of the return spring  36  opposite to the one end portion, namely, a lower end portion in the illustrated implementation may be supported with coming in contact with the protrusions  32   a  formed in the lower side of the hollow portion of the movable core  32 . 
     The cylinder  37  may accommodate the fixed core  31 , the movable core  32 , the coils  35 , and the return spring  36 . The movable core  32  may be moved upward and downward in the cylinder  37 . 
     The cylinder  37  may be located in the hollow portion formed through the pole portion of the bobbin  34 . An upper end portion of the cylinder  37  may come in contact with a lower surface of the supporting plate  14 . A side surface of the cylinder  37  may come in contact with an inner circumferential surface of the pole portion of the bobbin  34 . An upper opening of the cylinder  37  may be closed by the fixed core  31 . 
     The cylinder  37  may accommodate the shaft  320 . Inside the cylinder  37 , the shaft  320  may be moved upward or downward together with the movable core  32 . 
     3. Description of Movable Core Contact Part According to One Implementation 
     The DC relay  1  according to the implementation of the present disclosure may include a movable contactor part  40 . The movable contactor part  40  may be accommodated in the frame part  10 , specifically, in the inner space of the upper frame  11 . In detail, the movable contactor part  40  may be accommodated in the arc chamber  21  that is accommodated in the upper frame  11 . 
     The fixed contactor  22  may be located above the movable contactor part  40 . The movable contactor part  40  may be accommodated in the arc chamber  21  to be movable toward and away from the fixed contactor  22  (i.e., movable up and down in the illustrated implementation). 
     The core part  30  may be located below the movable contactor part  40 . The movable contactor part  40  may be accommodated to be movable toward and away from the fixed contactor  22  (i.e., movable up and down in the illustrated implementation), in response to the movement of the movable core  32 . 
     The movable contactor part  40  may include the movable contactor  210 . The movable contactor  210  may be brought into contact with or separated from the fixed contactor  22 , in response to the movement of the movable core  32  of the core part  30 . 
     In addition, the movable contactor part  40  may also include a coupling part  400  for stably maintaining a coupled state of each component of the movable contactor part  40 , in addition to the configuration for the contact between the fixed contactor  22  and the movable contactor  210 . 
     Hereinafter, a detailed description will be given of the movable contactor part  40  according to one implementation of the present disclosure, with reference to  FIGS. 5 to 17 . 
     In the illustrated implementation, the movable contactor part  40  may include an upper assembly  100 , a movable contactor assembly  200 , a lower assembly  300 , and a coupling part  400 . 
     (1) Description of Upper Assembly  100   
     The upper assembly  100  may be located on an upper side of the movable contactor part  40 . The upper assembly  100  may define an upper portion of the movable contactor part  40 . 
     The upper assembly  100  may surround the movable contactor assembly  200 . A lower portion of the upper assembly  100  may be coupled to the lower assembly  300 . 
     The coupling part  400  may be provided on an upper side of the upper assembly  100 . Each component of the upper assembly  100  can be stably coupled by the coupling part  400 . 
     The upper assembly  100  may include a housing  110  and an upper yoke  120 . 
     The housing  110  may be coupled to the lower assembly  300  to accommodate the movable contactor assembly  200 . 
     The housing  110  may have a rectangular parallelepiped shape with chambered edges. 
     Opposite sides of the housing  110 , namely, left and right sides in the illustrated implementation may be open. In addition, a lower side of the housing  110  may be open. That is, the housing  110  may have a cross section in a rectangular shape with a lower side open. The movable contactor assembly  200  may be inserted into the open space. 
     The housing  110  may include a first surface  111 , a second surface  112 , a housing plane  113 , a housing through hole  114 , and a housing space  115 . 
     The first surface  111  may define one side surface extending toward the lower assembly  300  among surfaces of the housing  110 . In the illustrated implementation, the first surface  111  may define a front surface. The first surface  111  may face the second surface  112 . 
     The first surface  111  may cover one side of the movable contactor  210  accommodated in the housing space  115 . The first surface  111  may cover one side of a lower yoke  220  accommodated in the housing space  115 . 
     A first bent portion  111   a  may be formed at one end portion of the first surface  111  facing the lower assembly  300 , namely, a lower end portion of the first surface  111  in the illustrated implementation. 
     The first bent portion  111   a  may be a portion at which the first surface  111  is coupled to the lower assembly  300 . In detail, the first bent portion  111   a  may be inserted into a bent portion  312   b  that forms a coupling slit  312  of a shaft support member  310 . 
     The first bent portion  111   a  may extend at a predetermined angle with respect to the first surface  111 . In the illustrated implementation, the first bent portion  111   a  may form a predetermined angle with the first surface  111  and extend outward, namely, toward the front in the illustrated implementation. 
     A plurality of first coupling holes  111   b  may be formed in a penetrating manner at one side of the first bent portion  111   a , namely, at an upper side of the first bent portion  111   a  in the illustrated implementation. After the first surface  111  is inserted into the coupling slit  312 , coupling members (not shown) may be coupled through the first coupling holes  111   b . Accordingly, the coupled state between the upper assembly  100  and the lower assembly  300  can be firmly maintained. 
     The second surface  112  may define one surface extending toward the lower assembly  300  among surfaces of the housing  110 . In the illustrated implementation, the second surface  112  may define a rear surface. The second surface  112  may face the first surface  111 . 
     The second surface  112  may cover another side of the movable contactor  210  accommodated in the housing space  115  that is opposite to the one side of the movable contactor  210 . The second surface  112  may cover another side of the lower yoke  220  accommodated in the housing space  115  that is opposite to the one side of the lower yoke  210 . 
     A second bent portion  112   a  may be formed at one end portion of the second surface  112  facing the lower assembly  300 , namely, a lower end portion of the second surface  111  in the illustrated implementation. 
     The second bent portion  112   a  may be a portion at which the second surface  112  is coupled to the lower assembly  300 . In detail, the second bent portion  112   a  may be inserted into a bent portion  312   b  that forms the coupling slit  312  of the shaft support member  310 . 
     The second bent portion  112   a  may extend at a predetermined angle with respect to the second surface  112 . In the illustrated implementation, the second bent portion  112   a  may form a predetermined angle with the second surface  112  and extend outward, namely, toward the rear in the illustrated implementation. 
     A plurality of second coupling holes  112   b  may be formed in a penetrating manner at one side of the second bent portion  112   a , namely, at an upper side of the second bent portion  112   a  in the illustrated implementation. After the second surface  112  is inserted into the coupling slit  312 , coupling members (not shown) may be coupled through the second coupling holes  112   b . Accordingly, the coupled state between the upper assembly  100  and the lower assembly  300  can be firmly maintained. 
     The first surface  111  and the second surface  112  may be formed overall in a rectangular shape. However, a width of the first surface  111  and the second surface  112  at portions adjacent to the housing plane  113  may be smaller than a width at portions adjacent to the lower assembly  300 . 
     The first surface  111  and the second surface  112  may be spaced apart from each other by a predetermined distance. The spaced distance between the first surface  111  and the second surface  112  may be equal to or larger than widths (lengths in a back and forth direction in the illustrated implementation) of the movable contactor  210  and the lower yoke  220 . 
     The housing plane  113  may define one surface of the housing  110 , namely, an upper surface in the illustrated implementation. The housing plane  113  may cover an upper side of the movable contactor  210  accommodated in the housing space  115 . 
     The first surface  111  and the second surface  112  may form predetermined angles with the housing plane  113  and extend toward the lower assembly  300 , namely, downward in the illustrated implementation. In one implementation, the angles formed between the first and second surfaces  111  and  112  and the housing plane  113  may be a right angle. 
     A lower side of the upper yoke  120  may come in contact with an upper side of the housing plane  113 . An upper side of the movable contactor  210  may come in contact with a lower side of the housing plane  113 . That is, the housing plane  113  may be located between the upper yoke  120  and the movable contactor  210 . 
     A pin member  410  and a support member  420  of the coupling part  400  may be inserted through the housing through hole  114 . 
     The housing through hole  114  may be formed through the housing plane  113 . In detail, the housing through hole  114  may formed through the housing plane  113  in the vertical direction. 
     In the illustrated implementation, the housing through hole  114  may be formed in a cylindrical shape with a central portion of the housing plane  113  as an axis. The shape of the housing through hole  114  may vary depending on a shape of the coupling part  400 . 
     The housing through hole  114  may preferably be formed coaxially with an upper yoke through hole  124  that is formed through the upper yoke  120 . In addition, the housing through hole  114  may have a larger diameter than the upper yoke through hole  124 . 
     The movable contactor assembly  200  may be inserted into the housing space  115 . The housing space  115  may be a space defined by the first surface  111 , the second surface  112 , the housing plane  113 , and the shaft support member  310  of the lower assembly  300 . 
     Specifically, the housing  110  may be formed so that both sides without the first surface  111  and the second surface  112 , namely, left and right sides in the illustrated implementation are open. 
     The movable contactor assembly  200  may be accommodated in the housing space  115  through the left or right open portions. In one implementation, the movable contactor assembly  200  may be accommodated in the housing space  115  in a sliding manner. 
     The upper yoke  120  may cancel electromagnetic repulsive force that may be generated between the fixed contactor  22  and the movable contactor  210 . The electromagnetic repulsive force may be mainly generated when the fixed contactor  22  and the movable contactor  210  are brought into contact with each other. 
     In detail, the upper yoke  120  may be magnetized when the fixed contactor  22  and the movable contactor  210  are electrically connected by being brought into contact with each other. In addition, as will be described later, the lower yoke  220  provided in the movable contactor assembly  200  may also be magnetized as the fixed contactor  22  and the movable contactor  210  are electrically connected by being brought into contact with each other. 
     Electromagnetic attractive force attractive force may be generated between the upper yoke  120  and the lower yoke  220 . At this time, since the upper yoke  120  is fixedly coupled to the housing  110 , the lower yoke  220  may have a tendency to move toward the upper yoke  120 . 
     As will be described later, the lower yoke  220  may support the lower side of the movable contactor  210 . Accordingly, as the lower yoke  220  receives electromagnetic attractive force attractive force in a direction toward the upper yoke  120 , the movable contactor  210  may receive force in a direction toward the fixed contactor  22 . 
     Therefore, even when the electromagnetic repulsive force is generated between the fixed contactor  22  and the movable contactor  210 , the contact between the fixed contactor  22  and the movable contactor  210  can be stably maintained by the electromagnetic attractive force attractive force between the upper yoke  120  and the lower yoke  220 . 
     The upper yoke  120  may have any shape capable of being magnetized by electromagnetic force generated by electric connection. In one implementation, the upper yoke  120  may be made of magnetizable iron, electromagnet, or the like. 
     In the illustrated implementation, the upper yoke  120  may be provided on an outer side of the housing  110 . The upper yoke  120  may surround upper portions of the first surface  111  and the second surface  112  of the housing  110 . Also, the upper yoke  120  may cover the housing plane  113  of the housing  110 . 
     As will be described later, a movable contactor part  40  according to another implementation of the present disclosure may include an upper yoke  130  provided on an inner side of the housing  110 . A detailed description thereof will be given later. 
     The upper yoke  120  may have a rectangular parallelepiped shape with chambered edges. 
     Opposite sides of the upper yoke  120 , namely, left and right sides in the illustrated implementation may be open. In addition, a lower side of the upper yoke  120  may be open. That is, the upper yoke  120  may have a cross section in a rectangular shape with a lower side open. The housing  110  may be coupled to the open space. 
     The upper yoke  120  may include a first upper yoke surface  121 , a second upper yoke surface  122 , an upper yoke plane  123 , and an upper yoke through hole  124 . 
     The first upper yoke surface  121  may define one surface extending toward the lower assembly  300  or the housing  110  among surfaces of the upper yoke  120 . In the illustrated implementation, the first upper yoke surface  121  may define a front surface. The first upper yoke surface  121  may face the second upper yoke surface  122 . 
     The first upper yoke surface  121  may partially cover the first surface  111 . Specifically, the first upper yoke surface  121  may cover a portion of the first surface  111  adjacent the housing plane  113 . 
     The second upper yoke surface  122  may define one surface extending toward the lower assembly  300  or the housing  110  among surfaces of the upper yoke  120 . In the illustrated implementation, the second upper yoke surface  122  may define a rear surface. The second upper yoke surface  122  may face the first upper yoke surface  121 . 
     The second upper yoke surface  122  may partially cover the second surface  112 . Specifically, the second upper yoke surface  122  may cover a portion of the second surface  112  adjacent to the housing plane  113 . 
     The first upper yoke surface  121  and the second upper yoke surface  122  may generally be formed in a rectangular shape and also be formed in a plate shape having a predetermined thickness. 
     The first upper yoke surface  121  and the second upper yoke surface  122  may be spaced apart from each other by a predetermined distance. The spaced distance between the first upper yoke surface  121  and the second upper yoke surface  122  may be equal to or larger than a length of the housing plane  113  (a length in the vertical direction in the illustrated implementation). 
     The upper yoke plane  123  may define one surface of the upper yoke  120 , namely, an upper surface in the illustrated implementation. The upper yoke plane  123  may cover an upper side of the housing plane  113  of the housing  110 . A lower side of the upper yoke plane  123  may come in contact with an upper side of the housing plane  113 . 
     The first upper yoke surface  121  and the second upper yoke surface  122  may form predetermined angles with the upper yoke plane  123  and extend toward the lower assembly  300 , namely, downward in the illustrated implementation. In one implementation, the angles formed between the first and second upper yoke surfaces  121  and  122  and the upper yoke plane  123  may be a right angle. 
     An upper side of the upper yoke plane  123  may be spaced apart from an inner surface of the arc chamber  21  by a predetermined distance. Even if the movable contactor part  40  is moved upward and the fixed contactor  22  and the movable contactor  210  come into contact with each other, the upper side of the upper yoke plane  123  and the inner surface of the arc chamber  21  may not come in contact with each other. This may result from the shape of the movable contactor  210  that extends back and forth, which will be described in detail later. 
     The pin member  410  and the support member  420  of the coupling part  400  may be inserted through the upper yoke through hole  124 . 
     The upper yoke through hole  124  may be formed through the upper yoke plane  123 . In detail, the upper yoke through hole  124  may be formed through the upper yoke plane  123  in the vertical (up and down) direction. 
     In the illustrated implementation, the upper yoke through hole  124  may be formed in a cylindrical shape with a central portion of the upper yoke plane  123  as an axis. The shape of the upper yoke through hole  124  may vary depending on the shape of the coupling part  400 . 
     The upper yoke through hole  124  may preferably be formed coaxially with the housing through hole  114 . In addition, the upper yoke through hole  124  may have a smaller diameter than the housing through hole  114 . 
     With this configuration, the pin member  410  and the support member  420  that are coupled through the housing through hole  114  and the upper yoke through hole  124  can be stably maintained in the coupled state. 
     (2) Description of Movable Contactor Assembly  200   
     The movable contactor assembly  200  may include the movable contactor  210  that is brought into contact with or separated from the fixed contactor  22  as the shaft  320  of the lower assembly  300  is moved up and down. The movable contactor assembly  200  may be accommodated in the housing space  115  of the housing  110  to be movable up and down. 
     The upper assembly  100  may be located on an upper side of the movable contactor assembly  200 . Specifically, the upper side of the movable contactor assembly  200  may come in contact with an inner surface of the housing  110 . 
     The lower assembly  300  may be located on a lower side of the movable contactor assembly  200 . Specifically, the movable contactor assembly  200  may be elastically supported by an elastic member  330  of the lower assembly  300 . 
     The movable contactor assembly  200  may include the movable contactor  210  and the lower yoke  220 . 
     The movable contactor  210  may come in contact with the fixed contactor  22  when control power is applied, so that the DC relay  1  can be electrically connected to an external power supply and a load. The movable contactor  210  may be separated from the fixed contactor  22  when control power is not applied, so that the DC relay  1  can be electrically disconnected from the external power supply and the load. 
     The upper side of the movable contact  110  may come in contact with the housing  110 . Specifically, the upper side of the movable contactor  210  may come in contact with an inner circumferential surface of the housing plane  113 . 
     The lower side of the movable contactor  210  may come in contact with the lower yoke  220 . In detail, the lower side of the movable contactor  210  may come in contact with an upper surface of the lower yoke  220 . 
     The movable contactor  210  may extend in the longitudinal direction, namely, in left and right directions in the illustrated implementation. That is, a length of the movable contactor  210  may be longer than its width. 
     Accordingly, when the movable contactor  210  is accommodated in the housing space  115 , both end portions of the movable contactor  210  in the longitudinal direction may be exposed to the outside of the housing space  115 . The both end portions may be brought into contact with the fixed contactor  22  when the movable contactor part  40  is moved upward. 
     With this configuration, even if the movable contactor part  40  is moved upward, the other parts except for the movable contactor  210  may not come into contact with the arc chamber  21  or the fixed contactor  22 . 
     The width of the movable contactor  210  may be the same as a width of the housing space  115 . In other words, the width of the movable contactor  210  may be the same as the predetermined distance by which the first surface  111  and the second surface  112  of the housing  110  are spaced apart from each other. 
     Accordingly, when the movable contactor  210  is accommodated in the housing space  115 , both opposite surfaces of the movable contactor  210  in a widthwise direction may come in contact with inner surfaces of the first surface  111  and the second surface  112 , respectively. 
     A thickness of the movable contactor  210  may be smaller than an extension length of the first upper yoke surface  121  and the second upper yoke surface  122  of the upper yoke  120 . In other words, when viewed in cross section, the thickness of the movable contactor  210  may be set such that the movable contactor  210  can be completely covered by the first upper yoke surface  121  and the second upper yoke surface  122  (see  FIG. 14 ). 
     With the configuration, the upper yoke  120  can effectively cancel electromagnetic repulsive force generated between the fixed contactor  22  and the movable contactor  210 . 
     In one implementation, the movable contactor  210  may be moved up and down by a predetermined distance together with the lower yoke  220  within the housing space  115 . The predetermined distance may be decided by the upper yoke  120 , the lower yoke  220 , and the elastic member  330 . 
     The movable contactor  210  may include a body portion  211 , protruding portions  212 , a support member accommodating portion  213 , a pin member coupling hole  214 , and a coupling protrusion  215 . 
     The body portion  211  may define a body of the movable contactor  210 . As described above, the body portion  211  may extend in the longitudinal direction, namely, in the left and right directions in the illustrated implementation. 
     The protruding portions  212  may protrude from a central portion of the body portion  211  in directions forming a predetermined angle with the longitudinal direction, namely, in the back and forth directions in the illustrated implementation. 
     The protruding portions  212  may be portions where the movable contactor  210  accommodated in the housing space  115  comes in contact with the inner surfaces of the first surface  111  and the second surface  112 . That is, the protruding portions  212  may be portions fitted to the housing  110  when the movable contactor  210  is accommodated in the housing space  115 . 
     Protrusion lengths of the protruding portions  212  may preferably be determined according to the spaced distance between the first surface  111  and the second surface  112 . Specifically, the sum of the protrusion lengths of the protruding portions  212  and a width of the body portion  211  may preferably be the same as the spaced distance between the first surface  111  and the second surface  112 . 
     With the configuration, the movable contactor  210  can be stably fitted when the movable contactor  210  is accommodated in the housing space  115 . 
     The support member  420  of the coupling part  400  may be inserted into the support member accommodating portion  213 . As described above, the support member  420  may be coupled through the housing through hole  114  and the upper yoke through hole  124 . 
     When the coupling of the support member  420  is completed, a base portion  421  formed on a lower side of the support member  420  may protrude from the inner surface of the housing plane  113 . 
     The support member accommodating portion  213  may be recessed by a predetermined distance into an upper surface of the body portion  211 , and thus the base portion  421  of the coupled support member  420  may be inserted into the support member accommodating portion  213 . 
     In the illustrated implementation, the support member accommodating portion  213  may be formed in a cylindrical shape having a circular cross section. The shape of the support member accommodating portion  213  may vary depending on a shape of the support member  420 . 
     In the illustrated implementation, the support member accommodating portion  213  may be formed with a center of the body portion  211  as a central axis. The support member accommodating portion  213  may change in position, but may preferably be formed to have the same central axis as the housing through hole  114  and the upper yoke through hole  124 . 
     A size of a cross section of the support member accommodating portion  213 , that is, a diameter of the support member accommodating portion  213  may vary. That is, as will be described later, when the lower yoke  220  is coupled to the lower side of the movable contactor  210 , the support member accommodating portion  213  and the pin member coupling hole  214  may be widened (expanded) by an arbitrary tool. 
     Accordingly, the diameter of the support member accommodating portion  213  may be increased, and thus the size of the cross section of the support member accommodating portion  213  may be increased. 
     The support member accommodating portion  213  may preferably be formed so that the increased size of the cross section is the same as a size of the base portion  421  of the support member  420 . 
     The pin member  410  of the coupling part  400  may be inserted through the pin member coupling hole  214 . The pin member coupling hole  214  may be formed through the body portion  211  in the longitudinal direction. 
     The pin member coupling hole  214  may be formed coaxially with the support member accommodating portion  213 . Accordingly, the pin member  410  and the support member  420  can be coaxially coupled, so as to be stably maintained in the coupled state. 
     In the illustrated implementation, the pin member coupling hole  214  may be formed in a cylindrical shape having a circular cross section. The shape of the pin member coupling hole  214  may vary depending on a shape of the pin member  410 . 
     A size of a cross section of the pin member coupling hole  214 , that is, a diameter of the pin member coupling hole  214  may vary. That is, as will be described later, when the lower yoke  220  is coupled to the lower side of the movable contactor  210 , the pin member coupling hole  214  as well as the support member accommodating portion  213  may be widened by an arbitrary tool. 
     Accordingly, the diameter of the pin member coupling hole  214  may be increased, and thus the size of the cross section of the pin member coupling hole  214  may be increased. 
     The pin member coupling hole  214  may preferably be formed so that the increased size of the cross section is larger than the diameter of the pin member  410 . This may result in preventing an electrical connection due to the contact between the pin member  410  and the movable contactor  210 . This may also allow the movable contactor  210  and the lower yoke  220  to be moved up and down by a predetermined distance, so as to prevent damage due to fixed coupling. 
     The coupling protrusion  215  may be a portion at which the lower yoke  220  is coupled to the movable contactor  210 . The coupling protrusion  215  may protrude by a predetermined distance from the lower surface of the movable contactor  210 . 
     A protrusion distance of the coupling protrusion  215  may be larger than a height of a yoke inner circumferential surface  222  of the lower yoke  220 . That is, a lower end portion of the coupling protrusion  215  may be located to be lower than the yoke inner circumferential surface  222 . 
     The coupling protrusion  215  may be formed coaxially with the central portion of the body portion  211 . That is, a central axis of the coupling protrusion  215  may be disposed coaxially with a central axis of the body portion  211 . Accordingly, the coupling protrusion  215  may also be disposed coaxially with the housing through hole  114 , the upper yoke through hole  124 , the support member accommodating portion  213 , and the pin member coupling hole  214 . 
     A hollow portion may be formed through the inside of the coupling protrusion  215  in a height direction. The hollow portion may communicate with the support member accommodating portion  213 . That is, it can be said that the hollow portion constitutes a part of the support member accommodating portion  213 . 
     The pin member  410  may be coupled through the movable contactor  210  such that one end portion thereof protrudes below the movable contactor  210  through the hollow portion. 
     The coupling protrusion  215  may have a circular cross section. That is, the coupling protrusion  215  may protrude from a lower surface of the body portion  211  toward the lower assembly  300 , namely, downward in the illustrated implementation. 
     The coupling protrusion  215  may include a coupling outer circumferential surface  215   a . The coupling outer circumferential surface  215   a  may define an outer surface of the coupling protrusion  215 . In the illustrated implementation, the coupling protrusion  215  may have a cylindrical shape, and the coupling outer circumferential surface  215   a  may be defined as a side surface of the coupling protrusion  215 . 
     The yoke inner circumferential surface  222  of the lower yoke  220  may come in contact with the coupling outer circumferential surface  215   a.    
     When the upper surface of the lower yoke  220  comes in contact with the lower surface of the movable contactor  210 , the coupling outer circumferential surface  215   a  and the yoke inner circumferential surface  222  may be spaced apart by a predetermined distance. At this time, as described above, the support member accommodating portion  213  and the pin member coupling hole  214  of the movable contactor  210  may be expanded by an arbitrary tool. 
     By the expansion, the coupling outer circumferential surface  215   a  may be moved toward the yoke inner circumferential surface  222 . As the expansion proceeds, the coupling outer circumferential surface  215   a  may come in contact with the yoke inner circumferential surface  222 . Accordingly, the movable contactor  210  and the lower yoke  220  can be fitted to each other without a separate member. 
     The lower yoke  220  may cancel electromagnetic repulsive force that may be generated between the fixed contactor  22  and the movable contactor  210 . The electromagnetic repulsive force may be mainly generated when the fixed contactor  22  and the movable contactor  210  are brought into contact with each other. 
     In detail, the lower yoke  220  may be magnetized when the fixed contactor  22  and the movable contactor  210  are electrically connected by being brought into contact each other. As described above, the electrical connection between the fixed contactor  22  and the movable contactor  210  may also magnetize the upper yoke  120 . 
     Electromagnetic attractive force attractive force may thusly be generated between the lower yoke  220  and the upper yoke  120 . At this time, since the upper yoke  120  is fixedly coupled to the housing  110 , the lower yoke  220  may have a tendency to move toward the upper yoke  120 . 
     As this time, the lower yoke  220  may support the lower side of the movable contactor  210 . Specifically, the upper surface of the lower yoke  220  may be brought into contact the lower surface of the movable contactor  210 . Accordingly, when the lower yoke  220  receives the electromagnetic attractive force attractive force in a direction toward the upper yoke  120 , the lower yoke  220  may apply force to the movable contactor  210  to be moved toward the upper yoke  120 . 
     Therefore, even when the electromagnetic repulsive force is generated due to the contact between the fixed contactor  22  and the movable contactor  210 , the contact between the fixed contactor  22  and the movable contactor  210  can be stably maintained by the electromagnetic attractive force attractive force between the upper yoke  120  and the lower yoke  220 . 
     The lower yoke  220  may have any shape capable of being magnetized by electromagnetic force generated by electric connection. In one implementation, the lower yoke  220  may be made of magnetizable iron, electromagnet, or the like. 
     The lower yoke  220  may have a rectangular parallelepiped shape in the longitudinal direction, namely, in the left and right directions in the illustrated implementation. That is, a length of the lower yoke  220  may be longer than its width. 
     Accordingly, when the lower yoke  220  is accommodated in the housing space  115 , both end portions of the lower yoke  220  in the longitudinal direction may be exposed to the outside of the housing space  115 . The both end portions may generate electromagnetic attractive force attractive force with the upper yoke  120 . 
     With this configuration, even when the electromagnetic repulsive force is generated between the fixed contactor  22  and the movable contactor  210 , the lower yoke  220  can cover most of the movable contactor  210  in the longitudinal direction. Accordingly, the contact state between the fixed contactor  22  and the movable contactor  210  can be stably maintained. 
     An extension length of the lower yoke  220  may be shorter than an extension length of the movable contactor  210 . 
     The lower yoke  212  may be provided with protruding portions protruding in directions forming a predetermined angle with the longitudinal direction, namely, in the back and forth directions in the illustrated implementation. A width of the lower yoke  220  provided with the protruding portions may be the same as a width of the housing space  115 . 
     In other words, the width of the lower yoke  220  provided with the protruding portions may be the same as the predetermined distance by which the first surface  111  and the second surface  112  of the housing  110  are spaced apart from each other. 
     Accordingly, when the lower yoke  220  is accommodated in the housing space  115 , both opposite surfaces of the lower yoke  220  in a widthwise direction may come in contact with the inner surfaces of the first surface  111  and the second surface  112 , respectively. With the configuration, the lower yoke  220  can be stably accommodated in the housing space  115 . 
     In one implementation, the lower yoke  220  may be moved up and down by a predetermined distance together with the movable contactor  210  within the housing space  115 . The predetermined distance may be decided by the upper yoke  120 , the lower yoke  220 , and the elastic member  330 . 
     A lower side of the lower yoke  220  may come in contact with an upper side of the elastic member  330 . That is, the elastic member  330  may not directly come in contact with the movable contactor  210 . Accordingly, even if the elastic member  330  is compressed and stretched repeatedly, the movable contactor  210  may not be damaged. 
     The lower yoke  220  may include a movable contactor coupling portion  221 , a yoke inner circumferential surface  222 , an elastic member support portion  223 , and a main inner surface  224 . 
     The movable contactor coupling portion  221  may be a portion at which the lower yoke  220  is coupled to the movable contactor  210 . In addition, the pin member  410  may be coupled through the movable contactor coupling portion  221 . 
     The movable contactor coupling portion  221  may be recessed by a predetermined distance into one surface of the lower yoke  220  facing the movable contactor  210 , namely, an upper surface of the lower yoke  220  in the illustrated implementation. 
     The movable contactor coupling portion  221  may communicate with the pin member coupling hole  214  of the movable contactor  210 . The pin member  410  coupled through the pin member coupling hole  214  may be inserted through the movable contactor coupling portion  221 . A diameter of the movable contactor coupling portion  221  may be larger than a diameter of the pin member coupling hole  214 . 
     One end portion of the pin member  410  coupled through the movable contactor coupling portion  221 , namely, a lower end portion of the pin member  410  in the illustrated implementation may be located to be lower than a lower surface of the lower yoke  220 . 
     The movable contactor coupling portion  221  may have the same central axis as the pin member coupling hole  214 . Accordingly, the movable contactor coupling portion  221  may also be disposed coaxially with the housing through hole  114 , the upper yoke through hole  124 , the support member accommodating portion  213 , and the pin member coupling hole  214 . 
     The diameter of the movable contactor coupling portion  221  may preferably be determined according to an expanded diameter of the coupling protrusion  215  of the movable contactor  210 . 
     That is, as described above, the diameter of the coupling protrusion  215  may be increased as the support member accommodating portion  213  and the pin member coupling hole  214  are expanded. In this case, the diameter of the movable contactor coupling portion  221  may be equal to or smaller than the diameter of the coupling protrusion  215 . 
     With this configuration, the lower yoke  220  can be coupled to the movable contactor  210  without a separate member. A detailed description thereof will be described later. 
     The yoke inner circumferential surface  222  may be a portion brought into contact with the coupling outer circumferential surface  215   a . The yoke inner circumferential surface  222  may be defined as an upper inner circumferential surface of the lower yoke  220 . 
     As described above, before the support member accommodating portion  213  and the pin member coupling hole  214  are expanded, the diameter of the coupling protrusion  215  may be smaller than the diameter of the movable contactor coupling portion  221 . Accordingly, the yoke inner circumferential surface  222  and the coupling outer circumferential surface  215   a  may be spaced apart from each other by a predetermined distance. 
     When the support member accommodating portion  213  and the pin member coupling hole  214  are expanded, the diameter of the coupling protrusion  215  may be increased. Accordingly, the coupling outer circumferential surface  215   a  can be moved toward the yoke inner circumferential surface  222  to be in contact with the yoke inner circumferential surface  222 . 
     This may allow the lower yoke  220  to be coupled to the movable contactor  210  without a separate member. 
     The elastic member support portion  223  may be a space in which an upper side of the elastic member  330  of the lower assembly  300  is accommodated. The elastic member support portion  223  may be recessed by a predetermined distance into the lower surface of the lower yoke  220 . 
     The elastic member support portion  223  may communicate with the movable contactor coupling portion  221 . In addition, the elastic member support portion  223  may communicate with the support member accommodating portion  213  of the movable contactor  210  and the pin member coupling hole  214 . 
     Accordingly, the pin member  410  inserted through the movable contactor  210  can pass through the lower yoke  220 . 
     The elastic member support portion  223  may be formed in a cylindrical shape having a predetermined diameter. In the illustrated implementation, the elastic member support portion  223  may have a diameter larger than the movable contactor coupling portion  221 . 
     When the expansion of the support member accommodating portion  213  and the pin member coupling hole  214  is completed, the coupling outer circumferential surface  215   a  and the yoke inner circumferential surface  222  may come in contact with each other. At this time, the protrusion length of the coupling protrusion  215  may be larger than a height of the yoke inner circumferential surface  222 . 
     Accordingly, a part of the lower side of the coupling outer circumferential surface  215   a  may protrude toward the elastic member support portion  223  without coming in contact with the yoke inner circumferential surface  222 . In this case, the part of the lower side of the coupling outer circumferential surface  215   a  and the main inner surface  224  of the lower yoke  220  defining the elastic member support portion  223  may be spaced apart from each other by a predetermined distance. 
     As will be described later, the elastic member  330  may be provided with an elastic hollow portion  331  defined therein. When the elastic member  330  is accommodated in the elastic member support portion  223 , the part of the lower side of the coupling protrusion  215  may be inserted into the elastic hollow portion  331 . In addition, a body of the elastic member  330  may be accommodated in the elastic member support portion  223  that is formed at a radially outside of the coupling protrusion  215 . 
     Accordingly, the elastic member  330  can be stably accommodated in the elastic member support portion  223 . 
     The main inner surface  224  may be an inner surface defining the elastic member support portion  223 . The main inner surface  224  may be defined as a lower inner circumferential surface of the inner circumferential surface of the lower yoke  220 . The outer circumferential surface of the elastic member  330  may come in contact with the main inner surface  224 . 
     (3) Description of Lower Assembly  300   
     The lower assembly  300  may define the lower side of the movable contactor part  40 . In addition, the lower assembly  300  may be connected to the core part  30  to transmit driving force generated by the movable core  32  or the return spring  36  to the movable contactor part  40 . The driving force transmitted by the lower assembly  300  may allow the movable contactor part  40  to be moved upward or downward. Accordingly, the fixed contactor  22  and the movable contactor  210  can be brought into contact with or separated from each other. 
     The lower assembly  300  may be coupled to the upper assembly  100  with a predetermined space formed therebetween. The predetermined space may be defined as the housing space  115 . The movable contactor assembly  200  may be accommodated in the housing space  115 . 
     The upper assembly  100  and the movable contactor assembly  200  are located above the lower assembly  300 . The core part  30  may be located below the lower assembly  300 . Movement of the core part  30 , that is, movement of the movable core  32  or movement by restoration of the return spring  36  may be transmitted to the lower assembly  300 . 
     The lower assembly  300  may include the shaft support member  310 , the shaft  320 , and the elastic member  330 . 
     The shaft support member  310  may define a body of the lower assembly  300 . The housing  110  of the upper assembly  100  may be coupled to the shaft support member  310 . 
     In addition, the shaft support member  310  may support a lower side of the elastic member  330 . Furthermore, the shaft  320  may be coupled to the shaft support member  310  so that the lower assembly  300  can be moved by the movable core  32  and the return spring  36 . 
     The shaft support member  310  may be coupled to the housing  110  with a predetermined space defined therebetween. 
     The shaft support member  310  may have a rectangular parallelepiped shape extending in the longitudinal direction, namely, in the back and forth direction in the illustrated implementation. 
     The shaft support member  310  may include housing coupling portions  311 , coupling slits  312 , an elastic member accommodating portion  313 , an elastic member coupling portion  314 , and a shaft coupling portion  315 . 
     The housing coupling portions  311  may be portions at which the housing  110  is coupled to the shaft support member  310 . Specifically, the lower end portion of the first surface  111  and the lower end portion of the second surface  112  may be coupled to the housing coupling portions  311 . 
     The housing coupling portions  311  may protrude from both end portions of the shaft support member  310  in the longitudinal direction, namely, from front and rear end portions in the illustrated implementation. The housing coupling portions  311  may protrude toward the housing  110 , namely, upward in the illustrated implementation. 
     Accordingly, a space between the housing coupling portions  311  located at the front side and the rear side may have a shape which is recessed compared to the housing coupling portions  311 . The space may be defined as the elastic member accommodating portion  313 . 
     A spaced distance between the housing coupling portions  311  may be longer than a length of the housing space  115  in the back and forth direction. That is, a spaced distance between outer surfaces of the housing coupling portions  311  may be longer than the spaced distance between the first surface  111  and the second surface  112 . 
     As the housing coupling portions  311  protrude, a sufficient depth can be secured for coupling the lower end portion of the first surface  111  and the lower end portion of the second surface  112 . 
     The lower end portion of the first surface  111  and the lower end portion of the second surface  112  may be coupled to the coupling slits  312 , respectively. The coupling slits  312  may be respectively recessed into the housing coupling portions  311  by predetermined distances. 
     A distance by which the coupling slits  312  are spaced apart from each other may be equal to a length of the housing space  115  in the back and forth direction. That is, the spaced distance between the coupling slits  312  may be the same as the spaced distance between the first surface  111  and the second surface  112 . 
     The shape of the coupling slits  312  may be determined to correspond to the shape of the first surface  111  and the second surface  112 . 
     Each of the coupling slits  312  may include a vertical portion  312   a  and a bent portion  312   b . The vertical portion  312   a  may be recessed into one surface of the housing coupling portion  311 , namely, an upper surface in the illustrated implementation, by a predetermined distance. 
     The vertical portion  312   a  may be vertically recessed with respect to the upper surface of the housing coupling portion  311 . The vertical portion  312   a  may communicate with the bent portion  312   b.    
     The bent portion  312   b  may be recessed by a predetermined distance at a predetermined angle with respect to the vertical portion  312   a . The predetermined angle formed between the bent portion  312   b  and the vertical portion  312   a  may be the same as a predetermined angle formed between the first surface  111  and the first bent portion  111   a . The predetermined angle formed between the bent portion  312   b  and the vertical portion  312   a  may be the same as a predetermined angle formed between the second surface  112  and the second bent portion  112   a.    
     The bent portion  312   b  may communicate with the vertical portion  312   a . Accordingly, the first surface  111  and the second surface  112  may be inserted into the bent portions  312   b  via the vertical portions  312   a , respectively. 
     As the bent portions  312   b  are formed, the coupled state between the housing  110  and the shaft support member  310  can be stably maintained compared to the case where only the vertical portions  312   a  are formed. 
     The elastic member accommodating portion  313  may be a space in which the elastic member  330  is accommodated. The elastic member accommodating portion  313  may be defined between the housing coupling portions  311 . 
     An upper boundary of the elastic member accommodating portion  313  may be defined by the movable contactor  210  and the lower yoke  220 . In addition, a boundary of the elastic member accommodating portion  313  in the back and forth direction may be defined by the first surface  111  and the second surface  112 . 
     That is, the elastic member accommodating portion  313  may be defined as a space surrounded by the housing  110 , the movable contactor  210 , the lower yoke  220 , and the shaft support member  310 . 
     The elastic member coupling portion  314  may support the lower side of the elastic member  330  accommodated in the elastic member accommodating portion  313 . Specifically, the elastic member coupling portion  314  may be inserted into the elastic hollow portion  331  of the elastic member  330 . This may prevent the elastic member  330  from being arbitrarily separated from the elastic member accommodating portion  313 . 
     The elastic member coupling portion  314  may protrude upward from one surface of the shaft support member  310 , namely, from an upper surface of the shaft support member  310  in the illustrated implementation. In the illustrated implementation, the elastic member coupling portion  314  may have a cylindrical shape with a circular cross section. A diameter of the elastic member coupling portion  314  may preferably be equal to or smaller than a diameter of the elastic hollow portion  331 . 
     The shaft coupling portion  315  may be a space into which a head portion  321  and a part of the shaft body portion  322  of the shaft  320  are coupled. The shaft coupling portion  315  may be formed inside the shaft support member  310 . 
     In one implementation, the shaft coupling portion  315  and the shaft  320  may be integrally formed with each other. In the implementation, the shaft coupling portion  315  and the shaft  320  may be formed by insert injection molding. 
     The shaft  320  coupled to the shaft coupling portion  315  may be moved integrally with the shaft support member  310 . Accordingly, when the shaft  320  is moved upward or downward, the shaft support member  310  may also be moved upward or downward. 
     The shaft  320  may transmit driving force, which is generated in response to the operation of the core part  30 , to the movable contactor part  40 . The shaft  320  may extend in the longitudinal direction, namely, in the up and down (vertical) direction in the illustrated implementation. 
     The shaft  320  may be coupled to the shaft support member  310 . Specifically, an upper side of the shaft  320  may be coupled to the shaft coupling portion  315 . 
     The shaft  320  may be coupled to the core part  30 . Specifically, a lower side of the shaft  320  may be brought into contact with the protrusions  32   a  of the movable core  32 , so that the shaft  320  can be moved together with the movable core  32 . 
     The shaft  320  may be coupled to the fixed core  31  to be movable up and down. In addition, the return spring  36  may be coupled through the shaft  320 . 
     The shaft  320  may include a head portion  321 , a shaft body portion  322 , and a movable core support portion  323 . 
     The head portion  321  may define an upper side of the shaft  320 . The head portion  321  may be formed in a circular plate shape. A diameter of the head portion  321  may be larger than a diameter of the shaft body portion  322 . 
     The head portion  321  may be inserted into the shaft coupling portion  315 . Due to the shape of the head portion  321 , the shaft  320  may not be arbitrarily separated from the shaft coupling portion  315 . 
     The shaft body portion  322  may extend downward from the head portion  321 . The shaft body portion  322  may define the body of the shaft  320 . The shaft body portion  322  may extend in the longitudinal direction. 
     The shaft body portion  322  may be coupled through the fixed core  31  to be movable up and down. The shaft  320  may extend in the longitudinal direction. 
     The movable core support portion  323  may be provided on a lower end portion of the shaft body portion  322 . The movable core support portion  323  may have a diameter smaller than the shaft body portion  322 . The movable core support portion  323  may be inserted into a space defined as the protrusions  32   a  of the movable core  32  are spaced apart from each other. 
     That is, one end portion of the shaft body portion  322  adjacent to the movable core support portion  323  may be supported by the protrusions  32   a  of the movable core  32 . Accordingly, when the movable core  32  is moved upward, the shaft  320  pushed by the protrusions  32   a  may be moved upward together with the movable core  32 . 
     The return spring  36  may be coupled through the shaft body portion  322 . A lower end portion of the return spring  36  may be supported by the protrusions  32   a  of the movable core  32 . Accordingly, when the movable core  32  is moved upward, the return spring  36  may be compressed and store restoring force. 
     When control power is not applied, the movable core  32  may not receive electromagnetic attractive force from the fixed core  31 . At this time, the movable core  32  may be moved downward by the restoring force stored in the return spring  36 . Accordingly, the shaft  320  may also be moved downward together with the movable core  32 . 
     The elastic member  330  may prevent the fixed contactor  22  and the movable contactor  210  from being arbitrarily separated from each other by electrostatic repulsive force. To this end, the elastic member  330  may elastically support the movable contactor assembly  200  at the lower side of the lower yoke  220 . 
     The elastic member  330  may be accommodated in the elastic member accommodating portion  313 . The lower side of the elastic member  330  accommodated in the elastic member accommodating portion  313  may be supported by the upper surface of the shaft support member  310 . In addition, the upper side of the elastic member  330  may come in contact with the elastic member support portion  223  so as to elastically support the lower yoke  220  and the movable contactor  210 . 
     The elastic member  330  may be formed in any shape capable of being compressed or stretched to store restoring force and transmitting the stored restoring force to the outside. In one implementation, the elastic member  330  may be configured as a coil spring. 
     The elastic member  330  may include an elastic hollow portion  331 . The elastic hollow portion  331  may be a space formed through the inside of the elastic member  330 . 
     The coupling protrusion  215  may be inserted into an upper side of the elastic hollow portion  331 . In addition, the elastic member coupling portion  314  may be inserted into a lower side of the elastic hollow portion  331 . Accordingly, the elastic member  330  can be stably accommodated in the elastic member accommodating portion  313  without being arbitrarily separated from the elastic member accommodating portion  313 . 
     (4) Description of Coupling Part  400   
     The coupling part  400  may be configured to firmly couple each component of the upper assembly  100 . In addition, the coupling part  400  may prevent the movable contactor  210  from being arbitrarily separated from the movable contactor part  40 . 
     The coupling part  400  may be fitted to the movable contactor part  40 . That is, the coupling part  400  may be coupled to the movable contactor part  40  by its own shape deformation without a separate coupling member. 
     The coupling part  400  may include a pin member  410  and a support member  420 . 
     The pin member  410  may prevent the movable contactor  210  from being arbitrarily separated from the movable contactor part  40 . To this end, the pin member  410  may be coupled sequentially through the upper yoke  120 , the housing  110 , the movable contactor  210 , and the lower yoke  220 . 
     Specifically, the pin member  410  may be inserted sequentially through the upper yoke through hole  124 , the housing through hole  114 , the pin member coupling hole  214 , and the movable contactor coupling portion  221 . The pin member  410  may be inserted until its one end portion, namely, a lower end portion in the illustrated implementation, is accommodated in the elastic hollow portion  331 . 
     Accordingly, the pin member  410  can prevent the movable contactor  210  from being arbitrarily separated from the housing space  115 . 
     The support member  420  may be provided on a radially outside of the pin member  410 . The pin member  410  may be fitted to the support member  420 . 
     That is, the support member  420  may be inserted through the upper yoke  120 , the housing  110 , and the movable contactor  210 . The pin member  410  may be coupled through a first hollow portion  423  and a second hollow portion  424  formed in the support member  420 . That is, coupling of the pin member  410  with the upper yoke  120  and the housing  110  may be achieved by the support member  420 . 
     The pin member  410  may extend in the longitudinal direction. In the illustrated implementation, the pin member  410  may be formed in a cylindrical shape having a circular cross section, but the shape may vary. 
     As will be described later, the pin member  410  may be deformed by pressure. In addition, when the application of the pressure is released, the pin member  410  may be restored in a radially outward direction (see  FIGS. 13 and 14 ). 
     To this end, the pin member  410  may be formed of a material having a predetermined elasticity. In one implementation, the pin member  410  may be formed of iron or stainless steel. 
     In a state where radially inward pressure is not applied, a diameter of the pin member  410  may preferably be larger than a diameter of the second hollow portion  424  of the support member  420 . 
     Also, in a state where radially inward pressure is applied, the diameter of the pin member  410  may preferably be equal to or smaller than the diameter of the second hollow portion  424  of the support member  420 . 
     The pin member  410  may include a cutout portion  411 , a hollow portion  412 , and an outer circumferential portion  413 . 
     The cutout portion  411  may be a space in which the outer circumferential portion  413  of the pin member  410  can be compressed radially inward when the pin member  410  receives radially inward pressure. The cutout portion  411  may be open along the longitudinal direction of the pin member  410 . 
     As the name implies, the cutout portion  411  may be formed by removing a part of the outer circumferential portion  413  of the pin member  410 . In one implementation, the cutout portion  411  may be formed by cutting out of the part of the outer circumferential portion  413 . 
     The cutout portion  411  may be defined by a first end portion  411   a  and a second end portion  411   b . The first end portion  411   a  may be one end portion of the outer circumferential portion  413  in a circumferential direction. The second end portion  411   b  may be another end portion of the outer circumferential portion  413  in the circumferential direction. 
     The first end portion  411   a  and the second end portion  411   b  may face each other. In addition, the first end portion  411   a  and the second end portion  411   b  may be spaced apart from each other by a predetermined distance. The cutout portion  411  may be a space which is defined as the first end portion  411   a  and the second end portion  411   b  are spaced apart from each other. 
     When radially inward pressure is applied to the pin member  410 , the outer circumferential portion  413  may be compressed radially inward and deformed. At this time, a displacement occurred due to the compression of the outer circumferential portion  413  may be compensated for by the cutout portion  411 . 
     In addition, a length of the cutout portion  411  in the circumferential direction, that is, the spaced distance between the first end portion  411   a  and the second end portion  411   b  may be determined according to the diameter of the second hollow portion  424  of the support member  420 . 
     That is, when the pin member  410  is compressed, the first end portion  411   a  and the second end portion  411   b  may be moved to be adjacent to each other, and the diameter of the pin member  410  may be reduced accordingly. In this instance, a maximum distance that the pin member  410  can be compressed may be determined to be the spaced distance between the first end portion  411   a  and the second end portion  411   b , that is, a circumferential length of the cutout portion  411 . 
     Therefore, the circumferential length of the cutout portion  411  may preferably be determined such that the diameter of the pin member  410  whose shape is deformed by receiving the radially inward pressure is equal to or smaller than the diameter of the second hollow portion  424 . 
     At the same time, the circumferential length of the cutout portion  411  may preferably be determined such that the diameter of the pin member  410  in the state in which the radially inward pressure is not applied is larger than the diameter of the second hollow portion  424 . 
     Accordingly, the pin member  410  can be coupled through the second hollow portion  424  by being changed in shape due to reception of the radially inward pressure. When the radially inward pressure is released after the coupling of the pin member  410  is completed, the pin member  410  may be deformed radially outward. Accordingly, the pin member  410  and the support member  420  can be firmly press-fitted to each other. 
     The hollow portion  412  may be a space defined inside the pin member  410 . The hollow portion  412  may be formed through the pin member  410  in the longitudinal direction of the pin member  410 . As the hollow portion  412  is formed, rigidity of the pin member  410  in the longitudinal direction can be increased. 
     In addition, as the hollow portion  412  is formed, the outer circumferential portion  413  can be changed in shape when the radially inward pressure is applied to the pin member  410 . 
     The outer circumferential portion  413  may define an outer circumference, namely, an outer boundary of the pin member  410 . In the illustrated implementation, since the pin member  410  has a cylindrical shape, the outer circumferential portion  413  may be defined as a side surface of the pin member  410 . 
     The outer circumferential portion  413  may be formed discontinuously. That is, a part of the outer circumferential portion  413  may be removed. The removed portion may be defined as the cutout portion  411 . The cutout portion  411  may be defined as a space between the first end portion  413   a  and the second end portion  413   b  of the outer circumferential portion  413 . 
     An outer surface of the outer circumferential portion  413  may be defined as an outer circumferential surface  413   a . The outer circumferential surface  413   a  may define an outer surface of the pin member  410 . When the pin member  410  is coupled to the support member  420 , the outer circumferential surface  413   a  may come in contact with a pin member contact surface  425  defining the second hollow portion  424 . 
     At this time, as described above, the pin member  410  may be coupled to the support member  420  in the state in which the diameter of the pin member  410  is reduced by receiving the radially inward pressure. Accordingly, the outer circumferential surface  413   a  can be brought into contact with the pin member contact surface  425  while applying radially outward pressure. 
     Accordingly, the pin member  410  and the support member  420  can be press-fitted to each other, so as to be stably maintained in the coupled state. 
     The support member  420  may allow stable coupling between the housing  110  and the upper yoke  120 . In addition, the pin member  410  may be coupled through the support member  420 . Since the support member  420  and the pin member  410  are press-fitted to each other, the pin member  410  coupled through the support member  420  cannot be arbitrarily separated. 
     The support member  420  may be located on an upper side of the upper assembly  100 . Specifically, the support member  420  may be coupled through the housing  110  and the upper yoke  120 . In addition, the support member  420  may be inserted into the movable contactor  210 . 
     At this time, the support member  420  may be deformed to be press-fitted to the housing  110 , the upper yoke  120 , and the movable contactor  210 . 
     In the illustrated implementation, the support member  420  may have a circular cross section and extend in the vertical direction. The shape of the support member  420  may vary to correspond to the shapes of the housing through hole  114 , the upper yoke through hole  124 , and the support member accommodating portion  213  to which the support member  420  is coupled. 
     The support member  420  may include a base portion  421 , a boss portion  422 , a first hollow portion  423 , a second hollow portion  424 , and a pin member contact surface  425 . 
     The base portion  421  may define one side of the support member  420 , namely, a lower side of the support member  420  in the illustrated implementation. The base portion  421  may be formed in a disk shape having a predetermined thickness. The shape of the base portion  421  may change to correspond to the shape of the support member accommodating portion  213 . 
     The base portion  421  may be inserted into the support member accommodating portion  213 . One surface of the base portion  421  facing the movable contactor  210 , namely, a lower surface in the illustrated implementation, may come in contact with the movable contactor  210 . 
     Another surface of the base portion  421  opposite to the one surface, namely, an upper surface in the illustrated implementation, may come in contact with the housing plane  113  of the housing  110 . That is, the base portion  421  may be located between the housing plane  113  and the movable contactor  210 . 
     The boss portion  422  may protrude by a predetermined distance from the one surface of the base portion  421  opposite to the movable contactor  210 , namely, from the upper surface in the illustrated implementation. 
     The boss portion  422  may be a portion of the support member  420  that is coupled through the housing  110  and the upper yoke  120 . Specifically, the boss portion  422  may be coupled through the housing through hole  114  and the upper yoke through hole  124 . 
     A protrusion distance of the boss portion  422  may preferably be determined to be larger than a sum of thicknesses of the housing plane  113  and the upper yoke plane  123 . That is, a part of the boss portion  422  may protrude to the outside of the upper yoke plane  123 . 
     The boss portion  422  may have a cylindrical shape extending in the vertical direction. The shape of the boss portion  422  may change to correspond to the shapes of the housing through hole  114  and the upper yoke through hole  124 . 
     The first hollow portion  423  and the second hollow portion  424  may be defined through the boss portion  422  in a height direction of the boss portion  422 . The first hollow portion  423  may be defined by a boss portion inner circumferential surface  422   a  forming an inner circumferential surface of the boss portion  422 . 
     The first hollow portion  423  may be a space defined inside the boss portion  422 . The first hollow portion  423  may be defined by the boss portion inner circumferential surface  422   a . That is, the first hollow portion  423  may be a space surrounded by the boss portion inner circumferential surface  422   a.    
     A pin member  410  may be coupled through the first hollow portion  423 . The first hollow portion  423  may communicate with the second hollow portion  424 . The first hollow portion  423  may be a space defined above the second hollow portion  424 . 
     The first hollow portion  423  may have a larger diameter than the second hollow portion  424 . This may allow smooth insertion of an arbitrary tool for expanding the first hollow portion  423  and the second hollow portion  424  radially outward, as will be described later. 
     The second hollow portion  424  may be a space located below the first hollow portion  423 . The second hollow portion  424  may communicate with the first hollow portion  423 . 
     The second hollow portion  424  may be a space defined inside the base portion  421  and the boss portion  422 . The second hollow portion  424  may be defined by the pin member contact surface  425 . That is, the second hollow portion  424  may be a space surrounded by the pin member contact surface  425 . 
     The pin member  410  may be coupled through the second hollow portion  424 . When the pin member  410  is coupled through the second hollow portion  424 , the outer circumferential surface  413   a  of the pin member  410  may be brought into contact with the pin member contact surface  425 . As described above, the outer circumferential surface  413   a  may be brought into contact with the pin member contact surface  425  while applying radially outward pressure to the pin member contact surface  425 . 
     An arbitrary tool may be inserted into the first hollow portion  423 . In one implementation, the arbitrary tool may be configured as a circular ring punch. 
     After the arbitrary tool is inserted into the first hollow portion  423 , it may further be inserted into the second hollow portion  424 . The arbitrary tool may apply radially outward pressure to the first hollow portion  423  and the second hollow portion  424 . 
     Accordingly, the first hollow portion  423  and the second hollow portion  424  may be expanded radially outward. At the same time, outer circumferences of the base portion  421  and the boss portion  422  may also be expanded radially outward. 
     At this time, the base portion  421  may be expanded until the upper surface of the base portion  421  is brought into contact with the lower surface of the housing plane  113 . At the same time, the boss portion  422  may be expanded until the outer circumferential surface of the boss portion  422  is brought into contact with the inner circumferential surface of the upper yoke plane  123  defining the upper yoke through hole  124 . 
     Accordingly, the housing  110 , the upper yoke  120 , and the support member  420  can be stably coupled by shape deformation of the support member  420  without a separate coupling member. 
     The pin member contact surface  425  may be defined as an inner circumferential surface of the support member  420  surrounding the second hollow portion  424 . The pin member contact surface  425  may have a height higher than the base portion  421 . 
     The pin member contact surface  425  may be located radially inward with respect to the boss portion inner circumferential surface  422   a . That is, the second hollow portion  424  defined by the pin member contact surface  425  may have a smaller diameter than the first hollow portion  423  defined by the boss portion inner circumferential surface  422   a.    
     4. Description of Method for Manufacturing Movable Contactor Part  40  According to Implementation 
     The movable contactor part  40  according to the implementation of the present disclosure may include the upper assembly  100 , the movable contactor assembly  200 , the lower assembly  300 , and the coupling part  400 . In this instance, the upper assembly  100 , the movable contactor assembly  200 , the lower assembly  300 , and the coupling part  400  may be stably coupled together by shape deformation of provided components without a separate member for coupling. 
     Hereinafter, a detailed description will be given of a method for manufacturing the movable contactor part  40  according to an implementation of the present disclosure, with reference to  FIGS. 7 to 22 . 
     (1) Description of Manufacturing Method (S 100 ) of Upper Assembly  100   
     A method for manufacturing the upper assembly  100  will be described with reference to  FIGS. 7, 8, 18, and 19 . 
     First, the housing  110  and the upper yoke  120  may be coupled to each other (S 110 ). Specifically, the housing  110  may be inserted into the space defined by the first upper yoke surface  121 , the second upper yoke surface  122 , and the upper yoke plane  123  of the upper yoke  120 . 
     At this time, the first upper yoke surface  121  and the second upper yoke surface  122  may cover the upper sides of the first surface  111  and the second surface  112  of the housing  110 , respectively. Inner surfaces of the first upper yoke surface  121  and the second upper yoke surface  122  may be brought into contact with outer surfaces of the first surface  111  and the second surface  112 , respectively. 
     Also, the upper yoke plane  123  may cover the housing plane  113 . To this end, the upper yoke plane  123  may extend longer than the housing plane  113 . 
     The housing through hole  114  may be formed through the housing plane  113 . In addition, the upper yoke through hole  124  may be formed through the upper yoke plane  123 . The housing through hole  114  and the upper yoke through hole  124  may be formed to have the same central axis. 
     When the coupling of the housing  110  and the upper yoke  120  is completed, the support member  420  may be coupled through the housing  110  and the upper yoke  120  (S 120 ). 
     The base portion  421  of the support member  420  may be a portion having the largest diameter. As described above, before the shape is changed by an arbitrary tool such as a circular ring punch, the diameter of the base portion  421  may be smaller than the diameter of the upper yoke through hole  124 . 
     Accordingly, the support member  420  may be smoothly coupled through the housing through hole  114  and the upper yoke through hole  124 . 
     The support member  420  may be inserted up to a height at which one surface of the base portion  421  that is expanded radially outward can come in contact with an inner surface of the housing plane  113 . 
     When the insertion of the support member  420  is completed, the arbitrary tool may be inserted into the first hollow portion  423  and the second hollow portion  424 . The arbitrary tool may be used to apply radially outward pressure to the support member  420 . The arbitrary tool may apply the pressure until the outer circumferential surface of the boss portion  422  is brought into contact with the inner circumferential surface of the upper yoke plane  123  surrounding the upper yoke through hole  124 . Accordingly, the support member  420  may be expanded radially outward (S 130 ). 
     Responsive to this, the first hollow portion  423  and the second hollow portion  424  may also be expanded radially outward. At the same time, the outer circumferential surfaces of the base portion  421  and the boss portion  422  may also be expanded radially outward. 
     When the expansion is completed, the outer circumferential surface of the boss portion  422  may be brought into contact with the inner circumferential surface of the upper yoke plane  123  surrounding the upper yoke through hole  124 . At this time, the support member  420  may be brought into contact with the upper yoke plane  123  while applying the radially outward pressure to the inner circumferential surface of the upper yoke plane  123  by the arbitrary tool. 
     Accordingly, the support member  420  and the upper assembly  100  may be coupled to each other without a separate coupling member. 
     At this time, the housing through hole  114  may be formed to have a larger diameter than the upper yoke through hole  124 . Accordingly, when the support member  420  is expanded radially outward, the outer circumferential surface of the support member  420  may first be brought into contact with the inner circumferential surface of the upper yoke plane  123  surrounding the upper yoke through hole  124 . 
     Accordingly, even if the shape of the support member  420  is changed, the housing  110  may not be damaged. 
     (2) Description of Coupling Process (S 200 ) Between Upper Assembly  100  and Lower Assembly  300   
     Hereinafter, a coupling process between the upper assembly  100  and the lower assembly  300  will be described in detail with reference to  FIGS. 9, 10, 18 , and  20 . 
     As described above, the shaft support member  310  and the shaft  320  constituting the lower assembly  300  may be integrally formed by insert injection or the like (S 210 ). 
     In addition, the elastic member  330  not illustrated in  FIGS. 9 and 10  may be coupled together with the movable contactor assembly  200 . 
     The first surface  111  and the second surface  112  of the housing  110  may be coupled to the housing coupling portions  311  of the shaft support member  310  (S 220 ). Specifically, one end portion of the first surface  111  and one end portion of the second surface  112  that face the lower assembly  300  may be inserted into the coupling slits  312 , respectively. 
     As aforementioned, the positions and shapes of the coupling slits  312  may be determined according to the positions and shapes of the first surface  111  and the second surface  112 . 
     At this time, the first bent portion  111   a  and the second bent portion  112   a  may be formed respectively on the first surface  111  and the second surface  112 . The first bent portion  111   a  and the second bent portion  112   a  may be inserted into the bent portions  312   b  through the vertical portions  312   a , respectively. 
     As the first bent portion  111   a  and the second bent portion  112   a  are inserted into the bent portions  312   b  of the coupling slits  312 , respectively, stable coupling may be achieved compared to a case where the housing  110  and the shaft support member  310  are coupled in the vertical direction. 
     Also, although not illustrated, through holes (not shown) may be formed through each housing coupling portion  311  in the back and forth direction. The through holes (not shown) may be aligned with the first coupling hole  111   b  and the second coupling hole  112   b  after the first surface  111  and the second surface  112  are inserted. 
     In addition, separate coupling members may be coupled through the through holes (not shown) and the coupling holes  111   b  and  112   b , respectively (S 230 ). In the implementation, the coupling between the housing  110  and the shaft support member  310  can be more firmly achieved. 
     (3) Description of Coupling Process (S 300 ) of Movable Contactor Assembly  200   
     Hereinafter, a process of coupling the movable contactor assembly  200  and a process of coupling the movable contactor assembly  200  with the upper assembly  100  and the lower assembly  300  will be described in detail with reference to  FIGS. 11, 12, 18, and 21 . 
     The lower yoke  220  may be provided on the lower side of the movable contactor  210 . The lower surface of the movable contactor  210  may come in contact with the upper surface of the lower yoke  220  (S 310 ). 
     The support member accommodating portion  213  may be recessed in the upper surface of the movable contactor  210 . In addition, the pin member coupling hole  214  may be formed through the movable contactor  210  in the height direction. The support member accommodating portion  213  and the pin member coupling hole  214  may communicate with each other. 
     The movable contactor coupling portion  221  may be formed through the radially inner side of the lower yoke  220  in the height direction. The coupling protrusion  215  of the movable contactor  210  may be inserted into the movable contactor coupling portion  221  (S 320 ). 
     In this case, the diameter of the coupling protrusion  215  may be smaller than the diameter of the movable contactor coupling portion  221 . Accordingly, the movable contactor  210  and the lower yoke  220  can be smoothly coupled to each other. 
     When the contact between the movable contactor  210  and the lower yoke  220  is completed, an arbitrary tool may be inserted into the support member accommodating portion  213  and the pin member coupling hole  214 . The arbitrary tool may be used to apply radially outward pressure to the movable contactor  210 . The arbitrary tool may apply pressure until the coupling outer circumferential surface  215   a  of the coupling protrusion  215  is brought into contact with the yoke inner circumferential surface  222 . Accordingly, the coupling protrusion  215  of the movable contactor  210  may be expanded radially outward (S 330 ). 
     Accordingly, the support member accommodating portion  213  and the pin member coupling hole  214  may also be expanded radially outward. At the same time, the coupling outer circumferential surface  215   a  may also be moved radially outward to be brought into contact with the yoke inner circumferential surface  222 . At this time, the movable contactor  210  may be brought into contact with the coupling outer circumferential surface  215   a  while applying radially outward pressure to the coupling outer circumferential surface  215   a  by the arbitrary tool. 
     Accordingly, the movable contactor  210  and the lower yoke  220  may be coupled to each other without a separate coupling member. 
     The completely-coupled movable contactor assembly  200  may then be coupled to the upper assembly  100  and the lower assembly  300  that are coupled to each other through those processes. At this time, although not shown, the elastic member  330  may also be coupled. 
     As aforementioned, one side of the elastic member  330  facing the movable contactor assembly  200  may be inserted into the elastic member support portion  223  and another side of the elastic member  330  opposite to the one side may be supported by the elastic member coupling portion  314 . 
     As described above, left and right sides of the housing  110  and the upper yoke  120  may be open. The movable contactor assembly  200  may be inserted through the left or right opening of the upper assembly  100  by the structure. 
     The movable contactor  210  and the lower yoke  220  may extend in the longitudinal direction. In addition, the extension lengths of the movable contactor  210  and the lower yoke  220  may be longer than the lengths of the housing  110  and the upper yoke  120  in the width direction (i.e., in the left and right direction in the illustrated implementation). Accordingly, both end portions of the movable contactor  210  and the lower yoke  220  in the longitudinal direction may be exposed to the outside. 
     When the coupling of the movable contactor assembly  200  is completed, the elastic member  330  may be located on the lower side of the movable contactor assembly  200 . The elastic member  330  may elastically support the movable contactor assembly  200 . Accordingly, even if electromagnetic repulsive force is generated between the fixed contactor  22  and the movable contactor  210 , the fixed contactor  22  and the movable contactor  210  may not be arbitrarily separated from each other. 
     (4) Description of Coupling Process (S 400 ) of Coupling Part  400   
     Hereinafter, a process in which coupling of the movable contactor part  40  is completed by coupling the coupling part  400  will be described in detail with reference to  FIGS. 13 to 18 and 22 . 
     Through those processes, the coupling of the upper assembly  100 , the movable contactor assembly  200 , and the lower assembly  300  may be completed. Since the movable contactor assembly  200  is elastically supported by the elastic member  330 , arbitrary separation of the movable contactor  210  can be prevented to some extent. 
     In the movable contactor part  40  according to the implementation of the present disclosure, the movable contactor  210  can be more stably maintained in the coupled state through the coupling part  400 . 
     In addition, the coupling part  400  may stably maintain the coupled state between the housing  110  of the upper assembly  100  and the upper yoke  120 . 
     Since the coupling process of the support member  420  of the coupling part  400  has been described above, the coupling process of the pin member  410  will be mainly described below. 
     Radially inward pressure may be applied to the pin member  410 . Accordingly, the distance between the first end portion  411   a  and the second end portion  411   b  of the pin member  410  may be reduced. As a result, the diameter of the pin member  410  may be reduced (S 410 ). 
     The pin member  410  may be inserted through the upper assembly  100  and the movable contactor assembly  200 . Specifically, the pin member  410  may be inserted through the first hollow portion  423  and the second hollow portion  424  of the support member  420  and the pin member coupling hole  214  of the movable contactor  210 . 
     Meanwhile, the support member  420  may be coupled through the housing  110  and the upper yoke  120 . Accordingly, the pin member  410  may be inserted through the upper yoke through hole  124  and the housing through hole  114  with intervening the support member  420  therebetween. 
     At this time, the pin member  410  may be inserted into the support member  420  and the movable contactor  210  while receiving radially inward pressure (S 420 ). The pressure may be applied by the aforementioned circular ring punch. 
     The cutout portion  411  may be formed in the pin member  410 . Accordingly, the pin member  410  which receives the radially inward pressure may be deformed to be reduced in diameter. That is, the cross section of the pin member  410  may be reduced. As described above, the reduction may be compensated for by the cutout portion  411 . 
     The reduction process may be performed until the diameter, namely, an outer diameter of the pin member  410  is equal to or smaller than the diameter of the second hollow portion  424 . Preferably, the reduction process may be performed until the diameter of the pin member  410  becomes smaller than the diameter of the second hollow portion  424 . Accordingly, the pin member  410  can be smoothly inserted into the support member  420 . 
     The insertion of the pin member  410  may be continued until one end portion of the pin member  410 , i.e., the lower end portion in the illustrated implementation is located in the elastic hollow portion  331  of the elastic member  330 . 
     When the pin member  410  is inserted up to a desired depth, the pressure applied to the pin member  410  may be released. Accordingly, the pin member  410  may be expanded radially outward. That is, the pin member  410  may restored to its original shape (S 430 ). 
     In this case, the diameter of the second hollow portion  424  may be smaller than the diameter of the pin member  410  before the shape of the pin member  410  changes. Accordingly, the expansion of the pin member  410  may be limited by the second hollow portion  424 . As a result, the outer circumferential surface  413   a  of the pin member  410  may be brought into contact with the pin member contact surface  425  of the second hollow portion  424  while applying the radially outward pressure. That is, the pin member  410  may be press-fitted to the support member  420 . 
     Accordingly, the pin member  410  and the support member  420  can be firmly coupled without a separate coupling member. 
     Also, there may be a case in which the pin member  410  is to be separated for maintenance or the like. In this case, the pin member  410  can be easily separated by simply applying radially inward pressure to the pin member  410 . 
     The pin member  410  may be inserted through the movable contactor  210  and the lower yoke  220  so that the lower end portion thereof is located closer to the lower assembly  300  than the lower surface of the lower yoke  220 . Accordingly, the movable contactor  210  can be more stably supported as compared to a case where only elastic support is provided by the elastic member  330 . 
     5. Description of Movable Contactor Part  40  According to Another Implementation 
     Hereinafter, a detailed description will be given of a movable contactor part  40  according to another implementation of the present disclosure, with reference to  FIGS. 23 and 24 . 
     This implementation has a difference in coupling relationship between the housing  110  and the upper yoke  130  provided in the upper assembly  100  as compared with the foregoing implementation. 
     That is, the foregoing implementation illustrates that the upper yoke  120  is disposed on the outer side of the housing  110 , whereas this implementation illustrates that the upper yoke  130  is disposed on an inner side of the housing  110 . 
     Except for the difference, the structures of the movable contactor assembly  200 , the lower assembly  300 , and the coupling part  400  are the same as those in the foregoing implementation. 
     Accordingly, hereinafter, the upper yoke  130  and the coupling relationship between the upper yoke  130  and other components will be mainly described. 
     The upper yoke  130  may be located inside the housing  110 . That is, the upper yoke  130  may be accommodated in the housing space  115 . The shape of the upper yoke  130  may be similar to the shape of the upper yoke  120  according to the foregoing implementation. 
     However, an extension length of an upper yoke plane  133  of the upper yoke  130  may be shorter than the extension length of the housing plane  113 . Specifically, the extension length of the upper yoke plane  133  may be equal to or shorter than the spaced distance between the first surface  111  and the second surface  112 . 
     A first upper yoke surface  131  and a second upper yoke surface  132  may extend respectively from both end portions of the upper yoke plane  133  in the longitudinal direction, namely, from a front end portion and a rear end portion in the illustrated implementation. 
     The first upper yoke surface  131  and the second upper yoke surface  132  may extend at a predetermined angle with the upper yoke plane  133 , respectively. In one implementation, the predetermined angle may be a right angle. 
     An outer surface of the first upper yoke surface  131  may come in contact with the inner surface of the first surface  111 . An outer surface of the second upper yoke surface  132  may come in contact with the inner surface of the second surface  112 . In addition, an upper surface of the upper yoke plane  133  may come in contact with the inner surface of the housing plane  113 . 
     An upper yoke space  135  may be defined by the first upper yoke surface  131 , the second upper yoke surface  132 , and the upper yoke plane  133 . The movable contactor assembly  200  may be accommodated in the upper yoke space  135 . 
     That is, the upper yoke space  135  may be configured to function as the housing space  115  in the foregoing implementation. 
     An upper yoke through hole  134  may be formed through the upper yoke plane  133 . The upper yoke through hole  134  may be formed through the upper yoke plane  133  in a height direction. Also, the upper yoke through hole  134  may be formed through a central portion of the upper yoke plane  133 . The upper yoke through hole  134  may be disposed to have the same central axis as the housing through hole  114 . 
     A diameter of the upper yoke through hole  134  may be larger than that of the housing through hole  114 . In this case, the support member  420  may be press-fitted to the housing  110 . 
     Alternatively, the diameter of the upper yoke through hole  134  may be smaller than the housing through hole  114 . In this case, the support member  420  may be press-fitted to the upper yoke  130 . 
     The support member  420  may be coupled sequentially through the housing through hole  114  and the upper yoke through hole  134 . The process in which the support member  420  is expanded by an arbitrary tool to be coupled to the housing  110  or the upper yoke  130  may be the same as that described above. 
     Although it has been described above with reference to preferred embodiments 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 
     
         
         
           
               1 : DC relay 
               10 : Frame part 
               11 : Upper frame 
               12 : Lower frame 
               13 : Insulating plate 
               14 : Supporting plate 
               20 : Opening/closing part 
               21 : Arc chamber 
               22 : Fixed contactor 
               23 : Sealing member 
               30 : Core part 
               31 ; Fixed core 
               32 : Movable core 
               32   a : Protrusion 
               33 : Yoke 
               34 : Bobbin 
               35 : Coil 
               36 : Return spring 
               37 : Cylinder 
               40 : Movable contactor part 
               100 : Upper assembly 
               110 : Housing 
               111 : First surface 
               111   a : First bent portion 
               111   b : First coupling hole 
               112 : Second surface 
               112   a : Second bent portion 
               112   b : Second coupling hole 
               113 : Housing plane 
               114 : Housing through hole 
               115 : Housing space 
               120 : Upper yoke 
               121 : First upper yoke surface 
               122 : Second upper yoke surface 
               123 : Upper yoke plane 
               124 : Upper yoke through hole 
               130 : Upper yoke 
               131 : First upper yoke surface 
               132 : Second upper yoke surface 
               133 : Upper yoke plane 
               134 : Upper yoke through hole 
               135 : Upper yoke space 
               200 : Movable contactor assembly 
               210 : Movable contactor 
               211 : Body portion 
               212 : Protruding portion 
               213 : Support member accommodating portion 
               214 : Pin member coupling hole 
               215 : Coupling protrusion 
               215   a : Coupling outer circumferential surface 
               220 : Lower yoke 
               221 : Movable contactor coupling portion 
               222 : Yoke inner circumferential surface 
               223 : Elastic member support portion 
               224 : Main inner surface 
               300 : Lower assembly 
               310 : Shaft support member 
               311 : Housing coupling portion 
               312 : Coupling slit 
               312   a : Vertical portion 
               312   b : Bent portion 
               313 : Elastic member accommodating portion 
               314 : Elastic member coupling portion 
               315 : Shaft coupling portion 
               320 : Shaft 
               321 : Head portion 
               322 : Shaft body portion 
               323 : Movable core support portion 
               330 : Elastic member 
               331 : Elastic hollow portion 
               400 : Coupling part 
               410 : Pin member 
               411 : Cutout portion 
               411   a : First end portion 
               411   b : Second end portion 
               412 : Hollow portion 
               413 : Outer circumferential portion 
               413   a : Outer circumferential surface 
               420 : Support member 
               421 : Base portion 
               422 : Boss portion 
               422   a : Boss portion inner circumferential surface 
               423 : First hollow portion 
               424 : Second hollow portion 
               425 : Pin member contact surface 
               1000 : DC relay according to the related art 
               1100 : Frame part according to the related art 
               1110 : Upper frame according to the related art 
               1120 ; Lower frame according to the related art 
               1200 : Contact part according to the related art 
               1210 : Fixed contact according to the related art 
               1220 : Movable contact according to the related art 
               1300 : Actuator according to the related art 
               1310 : Coil according to the related art 
               1320 : Bobbin according to the related art 
               1330 : Fixed core according to the related art 
               1340 : Movable core according to the related art 
               1350 : Movable shaft according to the related art 
               1360 : Spring according to the related art 
               1400 : Movable contact moving part according to the related art 
               1410 : Movable contact supporting portion according to the related art 
               1420 : Movable contact Cover portion according to the related art 
               1430 : Elastic portion according to the related art