Patent Publication Number: US-2020286702-A1

Title: Contact module, contact device, electromagnetic relay module, and electrical device

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to a contact module, a contact device, an electromagnetic relay module, and an electrical device, and more particularly relates to a contact module, a contact device, an electromagnetic relay module, and an electrical device, all of which are configured to selectively bring a moving contact into contact, or out of contact, with a fixed contact. 
     BACKGROUND ART 
     Patent Literature 1 discloses a contact device for selectively passing, or cutting off, an electric current through/at a contact. 
     Specifically, the contact device disclosed in Patent Literature 1 causes a moving contactor, included in the contact device, to be moved by electromagnetic force generated by energizing an excitation coil (excitation winding) of an electromagnet device, thereby bringing the moving contact of the moving contactor into contact with a fixed contact of a fixed terminal included in the contact device. This allows the moving contactor to be connected to the fixed terminal. 
     In the contact device described above, when an abnormal electric current such as a short-circuit current flows, for example, Lorenz force (i.e., electromagnetic repulsion) is applied to the moving contactor in such a direction as to bring the moving contact out of contact with the fixed contact, thus possibly decreasing the stability of connection between the moving contact and the fixed contact. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2014-232668 A 
     SUMMARY OF INVENTION 
     In view of the foregoing background, it is therefore an object of the present disclosure to provide a contact module, a contact device, an electromagnetic relay module, and an electrical device, all of which are configured to increase the stability of connection between the moving contact and the fixed contact. 
     A contact module according to an aspect of the present disclosure includes a pair of contact devices, which consists of one contact device and the other contact device. The one contact device includes one fixed terminal and one moving contactor. The one fixed terminal holds one fixed contact thereon. The one moving contactor holds one moving contact thereon and moves from a closed position where the one moving contact is in contact with the one fixed contact to an open position where the one moving contact is out of contact with the one fixed contact, and vice versa. The other contact device includes the other fixed terminal and the other moving contactor. The other fixed terminal holds the other fixed contact thereon. The other moving contactor holds the other moving contact thereon and moves from a closed position where the other moving contact is in contact with the other fixed contact to an open position where the other moving contact is out of contact with the other fixed contact, and vice versa. The pair of contact devices is arranged such that a direction in which the one moving contactor of the one contact device moves from the open position toward the closed position and a direction in which the other moving contactor of the other contact device moves from the open position toward the closed position are opposite from each other. The one moving contactor generates, when energized, a magnetic field that applies force, in a direction from the open position of the other moving contactor toward the closed position of the other moving contactor, to the other moving contactor, through which an electric current is flowing. The other moving contactor generates, when energized, a magnetic field that applies force, in a direction from the open position of the one moving contactor toward the closed position of the one moving contactor, to the one moving contactor, through which an electric current is flowing. 
     A contact module according to another aspect of the present disclosure includes: a pair of contact devices consisting of one contact device and the other contact device; and a magnetic shield member having magnetic properties. The one contact device includes one fixed terminal and one moving contactor. The one fixed terminal holds one fixed contact thereon. The one moving contactor holds one moving contact thereon and moves from a closed position where the one moving contact is in contact with the one fixed contact to an open position where the one moving contact is out of contact with the one fixed contact, and vice versa. The other contact device includes the other fixed terminal and the other moving contactor. The other fixed terminal holds the other fixed contact thereon. The other moving contactor holds the other moving contact thereon and moves from a closed position where the other moving contact is in contact with the other fixed contact to an open position where the other moving contact is out of contact with the other fixed contact, and vice versa. The pair of contact devices are arranged such that a direction in which the one moving contactor of the one contact device moves from the open position toward the closed position and a direction in which the other moving contactor of the other contact device moves from the open position toward the closed position are opposite from each other. The one moving contactor generates, when energized, a magnetic field that applies force, in a direction from the closed position of the other moving contactor toward the open position of the other moving contactor, to the other moving contactor, through which an electric current is flowing. The other moving contactor generates, when energized, a magnetic field that applies force, in a direction from the closed position of the one moving contactor toward the open position of the one moving contactor, to the one moving contactor, through which an electric current is flowing. The magnetic shield member is arranged between the one moving contactor and the other moving contactor. 
     A contact device according to still another aspect of the present disclosure is included in the contact module described above. 
     An electromagnetic relay module according to yet another aspect of the present disclosure includes: the contact module described above; and a pair of electromagnet devices consisting of one electromagnet device and the other electromagnet device. The one electromagnet device moves the one moving contactor, while the other electromagnet device moves the other moving contactor. 
     An electrical device according to yet another aspect of the present disclosure includes: the electromagnetic relay module described above; and a holding member. The holding member holds the electromagnetic relay module such that a direction in which the one moving contactor moves from the open position toward the closed position and a direction in which the other moving contactor moves from the open position toward the closed position are opposite from each other. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective view of an electromagnetic relay including a contact device according to a first embodiment; 
         FIG. 1B  is a cross-sectional view of the electromagnetic relay taken along the plane X 1 -X 1 ; 
         FIG. 2  is a cross-sectional view of the electromagnetic relay taken along the plane X 2 -X 2 ; 
         FIG. 3  illustrates how a first yoke and a second yoke of the contact device attract each other; 
         FIG. 4  illustrates a relative position of the first yoke with respect to a moving contactor; 
         FIG. 5  illustrates how to stretch an arc generated in the contact device; 
         FIG. 6  is a circuit diagram illustrating how a contact module according to a first embodiment, a battery, and a load may be connected together; 
         FIG. 7  is a perspective view of an electrical device according to the first embodiment; 
         FIG. 8  illustrates relative positions of a moving contactor of one contact device and a moving contactor of the other contact device according to the first embodiment and repulsive forces produced between the moving contactor of the one contact device and the moving contactor of the other contact device; 
         FIG. 9  illustrates relative positions of one contact device and the other contact device according to a variation of the first embodiment; 
         FIG. 10  illustrates relative positions of the moving contactor of the one contact device and the moving contactor of the other contact device and attractive forces produced between the moving contactor of the one contact device and the moving contactor of the other contact device; 
         FIG. 11  illustrates relative positions of a moving contactor of one contact device and a moving contactor of the other contact device according to a second embodiment and attractive forces produced between the moving contactor of the one contact device and the moving contactor of the other contact device; and 
         FIG. 12  illustrates relative positions of a moving contactor of one contact device and a moving contactor of the other contact device according to a variation of the second embodiment and repulsive forces produced between the moving contactor of the one contact device and the moving contactor of the other contact device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Note that embodiments and their variations to be described below are only examples of the present disclosure and should not be construed as limiting. Rather, those embodiments and variations may be readily modified in various manners depending on a design choice or any other factor without departing from a true spirit and scope of the present disclosure. It should also be noted that the drawings to be referred to in the following description of embodiments and their variations are all schematic representations. That is to say, the ratio of the dimensions (including thicknesses) of respective constituent elements illustrated on the drawings does not always reflect their actual dimensional ratio. 
     First Embodiment 
     A contact module  91  according to a first embodiment and an electrical device  900  will be described with reference to  FIGS. 1A-8 . 
     (1) Configuration 
     (1.1) Overall Configuration 
     An electrical device  900  according to this embodiment includes: an electromagnetic relay module  910 ; and a holding member  920  for holding the electromagnetic relay module  910 . The electromagnetic relay module  910  includes: a contact module  91  including a pair of contact devices  1 ; and a pair of electromagnet devices  10 . Each of these contact devices  1  forms, along with an associated electromagnet device  10 , an electromagnetic relay  100 . In other words, each electromagnetic relay  100  includes an associated contact device  1  and an associated electromagnet device  10 . In the following description, when the pair of contact devices  1  need to be distinguished from each other, one contact device  1  will be hereinafter referred to as a “contact device  1 A” and the other contact device  1  will be hereinafter referred to as a “contact device  1 B.” Likewise, when the pair of electromagnet devices  10  need to be distinguished from each other, one electromagnet device  10  will be hereinafter referred to as an “electromagnet device  10 A” and the other electromagnet device  10  will be hereinafter referred to as an “electromagnet device  10 B.” Furthermore, when the pair of electromagnetic relays  100  need to be distinguished from each other, one electromagnetic relay  100  will be hereinafter referred to as an “electromagnetic relay  100 A” and the other electromagnetic relay  100  will be hereinafter referred to as an “electromagnetic relay  100 B.” 
     Each contact device  1  includes a pair of fixed terminals  31 ,  32  and a moving contactor  8  (see  FIG. 1B ). Each of the fixed terminals  31 ,  32  holds a fixed contact  311 ,  321  thereon. The moving contactor  8  holds a pair of moving contacts  81 ,  82  thereon. 
     Each electromagnet device  10  includes a mover  13  and an excitation coil  14  (see  FIG. 1B ). The electromagnet device  10  is configured to have the mover  13  attracted by a magnetic field generated by the excitation coil  14  when the excitation coil  14  is energized. Attracting the mover  13  causes the moving contactor  8  to move from an open position to a closed position. As used herein, the “open position” refers to the position of the moving contactor  8  when the moving contacts  81 ,  82  go out of contact with the fixed contacts  311 ,  312 , respectively. Also, as used herein, the “closed position” refers to the position of the moving contactor  8  when the moving contacts  81 ,  82  come into contact with the fixed contacts  311 ,  312 , respectively. 
     Also, in this embodiment, the mover  13  is arranged along a line L and configured to reciprocate straight along the line L. The excitation coil  14  is configured as a conductive wire (electric wire) wound around the line L. That is to say, the line L corresponds to the center axis of the excitation coil  14 . 
     In the embodiment to be described below, each contact device  1  is supposed to form, along with its associated electromagnet device  10 , the electromagnetic relay  100  as shown in  FIG. 1A . However, this is only an example and should not be construed as limiting. The contact device  1  does not have to be applied to the electromagnetic relay  100  but may also be used in a breaker (circuit breaker), a switch, or any other type of electrical equipment. Also, in the embodiment to be described below, the electromagnetic relay  100  is supposed to be used as a part of onboard equipment for an electric vehicle (EV). In that case, the fixed terminals  31 ,  32  and moving contactor  8  of the contact device  1 A are electrically connected on a high-potential side of the path along which DC power is supplied from a traveling battery E 1  to a load R 1  (such as an inverter), and the fixed terminals  31 ,  32  and moving contactor  8  of the contact device  1 B are electrically connected on a low-potential side of the path, as shown in  FIG. 6 . 
     (1.2) Contact Device 
     Next, a configuration for the contact devices  1  will be described. 
     As shown in  FIGS. 1A and 1B , each contact device  1  includes the pair of fixed terminals  31 ,  32 , the moving contactor  8 , a housing  4 , a flange  5 , and two bus bars  21 ,  22 . The contact device  1  further includes a first yoke  6 , a second yoke  7 , two capsule yokes  23 ,  24 , two arc extinction magnets (permanent magnets)  25 ,  26 , an insulation plate  41 , and a spacer  45 . The fixed terminal  31  holds the fixed contact  311  thereon, and the fixed terminal  32  holds the fixed contact  321  thereon. The moving contactor  8  is a plate member made of a metallic material with electrical conductivity. The moving contactor  8  holds a pair of moving contacts  81 ,  82 , which are arranged to face the pair of fixed contacts  311 ,  321 , respectively. 
     In the following description, in the contact device  1 A, the direction in which the fixed contacts  311 ,  321  and the moving contacts  81 ,  82  face each other is defined herein to be an upward/downward direction, and the fixed contacts  311 ,  321  are located on an upper side when viewed from the moving contacts  81 ,  82 , just for the sake of convenience. In addition, in the contact device  1 A, the direction in which the pair of fixed terminals  31 ,  32  (i.e., the pair of fixed contact  311 ,  321 ) are arranged side by side is defined herein to be a rightward/leftward direction, and the fixed terminal  32  is supposed to be located on the right when viewed from the fixed terminal  31 . That is to say, in the following description, the upward, downward, rightward, and leftward directions are supposed to be defined on the basis of the directions shown in  FIG. 1B . Furthermore, in the following description, the direction perpendicular to both the upward/downward direction and the rightward/leftward direction (i.e., the direction coming out of the paper on which  FIG. 1B  is depicted) is defined herein to be a forward/backward direction. Note that these directions should not be construed as limiting a mode of using the contact module  91 , the contact devices  1 , the electromagnetic relay module  910 , or the electrical device  900 . 
     The contact device  1 A and the contact device  1 B have the same configuration but the contact device  1 B is arranged with respect to the contact device  1 A such that the respective members of the contact device  1 B are inverted both in the upward/downward direction and the rightward/leftward direction with respect to their counterparts of the contact device  1 A. In the following description, only the constituent elements of the contact device  1 A will be described. Description of the corresponding constituent elements of the contact device  1 B will be omitted herein, because those constituent elements of the contact device  1 B are just arranged upside down with respect to their counterparts of the contact device  1 A. 
     One (first) fixed contact  311  is held at the lower end (one end) of one (first) fixed terminal  31 . The other (second) fixed contact  321  is held at the lower end (one end) of the other (second) fixed terminal  32 . 
     The pair of fixed terminals  31 ,  32  are arranged side by side in the rightward/leftward direction (see  FIG. 1B ). Each of the pair of fixed terminals  31 ,  32  is made of an electrically conductive metallic material. The pair of fixed terminals  31 ,  32  serve as terminals for connecting an external circuit (including a battery and a load) to the pair of fixed contacts  311 ,  321 . In this embodiment, the fixed terminals  31 ,  32  are supposed to be made of copper (Cu), for example. However, this is only an example and should not be construed as limiting. Alternatively, the fixed terminals  31 ,  32  may also be made of any electrically conductive material other than copper. 
     Each of the pair of fixed terminals  31 ,  32  is formed in the shape of a cylinder, of which a cross section, taken along a plane intersecting with the upward/downward direction at right angles, is circular. In this embodiment, each of the pair of fixed terminals  31 ,  32  is formed in a T-shape in a front view such that its diameter at the upper end (at the other end) is larger than its diameter at the lower end (at the one end). The pair of fixed terminals  31 ,  32  are each held by the housing  4  such that part of the fixed terminal  31 ,  32  protrudes (at the other end) from the upper surface of the housing  4 . Specifically, each of the pair of fixed terminals  31 ,  32  is fixed onto the housing  4  so as to run through an opening cut through the upper wall of the housing  4 . 
     The moving contactor  8  is formed in the shape of a plate having thickness in the upward/downward direction and having a greater dimension in the rightward/leftward direction than in the forward/backward direction. The moving contactor  8  is arranged under the pair of fixed terminals  31 ,  32  such that both longitudinal ends thereof (i.e., both ends thereof in the rightward/leftward direction) face the pair of fixed contacts  311 ,  321  (see  FIG. 1B ). Portions, respectively facing the pair of fixed contacts  311 ,  321 , of the moving contactor  8  are provided with the pair of moving contacts  81 ,  82 , respectively (see  FIG. 1B ). 
     The moving contactor  8  is housed in the housing  4 . The moving contactor  8  is moved up and down (i.e., in the upward/downward direction) by the electromagnet device  10  arranged under the housing  4 , thus allowing the moving contactor  8  to move from the closed position to the open position, and vice versa.  FIG. 1B  illustrates a state where the moving contactor  8  is currently located at the closed position. In this state, the pair of moving contacts  81 ,  82  held by the moving contactor  8  are in contact with their associated fixed contacts  311 ,  321 , respectively. On the other hand, in a state where the moving contactor  8  is currently located at the open position, the pair of moving contacts  81 ,  82  held by the moving contactor  8  are out of contact with their associated fixed contacts  311 ,  321 , respectively. 
     Therefore, when the moving contactor  8  is currently located at the closed position, the pair of fixed terminals  31 ,  32  are short-circuited together via the moving contactor  8 . That is to say, when the moving contactor  8  is currently located at the closed position, the moving contacts  81 ,  82  come into contact with the fixed contacts  311 ,  321 , respectively, and therefore, the fixed terminal  31  is electrically connected to the fixed terminal  32  via the fixed contact  311 , the moving contact  81 , the moving contactor  8 , the moving contact  82 , and the fixed contact  321 . In this embodiment, a positive electrode of the battery E 1  is electrically connected to the fixed terminal  31  of the contact device  1 A and the load R 1  is electrically connected to the fixed terminal  32  of the contact device  1 A as shown in  FIG. 6 . In addition, a negative electrode of the battery E 1  is electrically connected to the fixed terminal  32  of the contact device  1 B and the load R 1  is electrically connected to the fixed terminal  31  of the contact device  1 B. Thus, while the moving contactor  8  is currently located at the closed position in each of the contact devices  1 A,  1 B, the contact device  1 A,  1 B forms a path through which DC power is supplied from the battery E 1  to the load R 1 . 
     In this embodiment, the moving contacts  81 ,  82  only need to be held by the moving contactor  8 . Therefore, the moving contacts  81 ,  82  may be formed by hammering out portions of the moving contactor  8 , for example, so as to form integral parts of the moving contactor  8 . Alternatively, the moving contacts  81 ,  82  may be members provided separately from the moving contactor  8  and may be secured, by welding, for example, onto the moving contactor  8 . Likewise, the fixed contacts  311 ,  321  only need to be held by the fixed terminals  31 ,  32 , respectively. Therefore, the fixed contacts  311 ,  321  may form integral parts of the fixed terminals  31 ,  32 , respectively. Alternatively, the fixed contacts  311 ,  321  may be members provided separately from the fixed terminals  31 ,  32  and may be secured, by welding, for example, onto the fixed terminals  31 ,  32 , respectively. 
     The moving contactor  8  has a through hole  83  at a middle portion thereof. In this embodiment, the through hole  83  is provided at a halfway point between the pair of moving contacts  81 ,  82  of the moving contactor  8 . The through hole  83  runs through the moving contactor  8  along the thickness thereof (i.e., in the upward/downward direction). The through hole  83  is provided to pass a shaft  15  (to be described later) therethrough. 
     The first yoke  6  is configured as a ferromagnetic body and may be made of a metallic material such as iron. The first yoke  6  is secured to the tip (upper end) of the shaft  15 . The shaft  15  runs through the moving contactor  8  through the through hole  83  thereof and the tip (upper end) of the shaft  15  protrudes upward from the upper surface of the moving contactor  8 . Thus, the first yoke  6  is located over the moving contactor  8  (see  FIG. 1B ). Specifically, in the direction in which the moving contactor  8  moves, the first yoke  6  is located on the same side as the fixed contacts  311 ,  321  with respect to the moving contactor  8 . 
     When the moving contactor  8  is currently located at the closed position, a predetermined gap L 1  is left between the moving contactor  8  and the first yoke  6  (see  FIG. 4 ). That is to say, when the moving contactor  8  is located at the closed position, the first yoke  6  is spaced from the moving contactor  8  by the gap L 1  in the upward/downward direction. For example, if the moving contactor  8 , the shaft  15 , and the first yoke  6  are electrically insulated from each other at least partially, then electrical insulation is ensured between the moving contactor  8  and the first yoke  6 . 
     The second yoke  7  is a ferromagnetic body and may be made of a metallic material such as iron. The second yoke  7  is fixed on the lower surface of the moving contactor  8  (see  FIG. 1B ). Thus, as the moving contactor  8  moves up and down (in the upward/downward direction), the second yoke  7  also moves up and down (in the upward/downward direction). Optionally, an insulating layer  90  with electrical insulation properties may be provided on the upper surface (particularly, a portion to come in contact with the moving contactor  8 ) of the second yoke  7  (see  FIG. 4 ). This ensures electrical insulation between the moving contactor  8  and the second yoke  7 . Note that in  FIGS. 1B, 2, 8, 10, 11, 12 , and other drawings, illustration of the insulating layer  90  is omitted as appropriate. 
     The second yoke  7  also has a through hole  71  at a middle portion thereof. In this embodiment, the through hole  71  is aligned with the through hole  83  of the moving contactor  8 . The through hole  71  runs through the second yoke  7  along the thickness thereof (i.e., in the upward/downward direction). The through hole  71  is provided to pass the shaft  15  and a contact pressure spring  17  (to be described later) therethrough. 
     The second yoke  7  has, at both ends in the forward/backward direction, a pair of protrusions  72 ,  73  protruding upward (see  FIG. 2 ). In other words, at both ends in the forward/backward direction of the upper surface of the second yoke  7 , provided are protrusions  72 ,  73  protruding in the direction in which the moving contactor  8  moves from the open position toward the closed position (i.e., upward in this embodiment). That is to say, at least part of the second yoke  7  is located opposite from the fixed contacts  311 ,  321  with respect to the moving contactor  8  in the direction in which the moving contactor  8  moves. 
     When the second yoke  7  has such a shape, the tip surface (i.e., upper end face) of the front protrusion  72 , out of the pair of protrusions  72 ,  73 , is abutted on a frontend portion  61  of the first yoke  6 , while the tip surface (i.e., upper end face) of the rear protrusion  73 , out of the pair of protrusions  72 ,  73 , is abutted on a rear end portion  62  of the first yoke  6  as shown in  FIG. 3 . Thus, when an electric current I flows through the moving contactor  8  in the direction shown as an example in  FIG. 3 , a magnetic flux φ 1  is generated to pass through a magnetic path formed by the first yoke  6  and the second yoke  7 . At this time, the frontend portion  61  of the first yoke  6  and the tip surface of the protrusion  73  turn into N pole and the rear end portion  62  of the first yoke  6  and the tip surface of the protrusion  72  turn into S pole, thus producing attractive force between the first yoke  6  and the second yoke  7 . 
     The capsule yokes  23 ,  24  are configured as ferromagnetic bodies and may be made of a metallic material such as iron. The capsule yokes  23 ,  24  each hold an arc extinction magnet  25 ,  26 . The capsule yokes  23 ,  24  are arranged on both sides in the forward/backward direction (i.e., in front of and behind) with respect to the housing  4  so as to surround the housing  4  on both sides in the forward/backward direction (see  FIG. 5 ). In  FIG. 5 , illustration of the bus bars  21 ,  22  is omitted. 
     The arc extinction magnets  25 ,  26  are arranged such that their poles facing each other in the rightward/leftward direction have mutually opposite polarities. In other words, the arc extinction magnets  25 ,  26  are arranged as extensions in the direction in which an electric current I flows through the moving contactor  8 . The arc extinction magnets  25 ,  26  are arranged at right and left ends of the housing  4 . The arc extinction magnets  25 ,  26  stretch the arc generated between the moving contacts  81 ,  82  and the fixed contacts  311 ,  321  while the moving contactor  8  moves from the closed position toward the open position. The capsule yokes  23 ,  24  encapsulate the housing  4  as well as the arc extinction magnets  25 ,  26  in their entirety. In other words, the arc extinction magnets  25 ,  26  are interposed between the right and left end faces of the housing  4  and the capsule yokes  23 ,  24 . Specifically, one surface in the rightward/leftward direction (i.e., left end face) of one (left) arc extinction magnet  25  is coupled to one end of the capsule yokes  23 ,  24  and the other surface in the rightward/leftward direction (i.e., right end face) of the arc extinction magnet  25  is coupled to the housing  4 . One surface in the rightward/leftward direction (i.e., right end face) of the other (right) arc extinction magnet  26  is coupled to the other end of the capsule yokes  23 ,  24  and the other surface in the rightward/leftward direction (i.e., left end face) of the arc extinction magnet  26  is coupled to the housing  4 . In this embodiment, the arc extinction magnets  25 ,  26  are arranged such that their poles facing each other in the rightward/leftward direction have mutually opposite polarities. However, this is only an example and should not be construed as limiting. Alternatively, the arc extinction magnet  25 ,  26  may also be arranged such that their poles facing each other in the rightward/leftward direction have the same polarity. 
     In this embodiment, while the moving contactor  8  is currently located at the closed position, the respective points of contact between the pair of fixed contacts  311 ,  321  and the pair of moving contacts  81 ,  82  are located between the arc extinction magnets  25 ,  26  (see  FIG. 1B ). That is to say, the respective points of contact between the pair of fixed contacts  311 ,  321  and the pair of moving contacts  81 ,  82  fall within a magnetic field generated between the arc extinction magnets  25 ,  26 . 
     According to this configuration, the capsule yoke  23  forms part of a magnetic circuit, through which a magnetic flux φ 2  generated by the pair of arc extinction magnets  25 ,  26  passes, as shown in  FIG. 5 . Likewise, the capsule yoke  24  also forms part of a magnetic circuit, through which a magnetic flux φ 2  generated by the pair of arc extinction magnets  25 ,  26  passes, as shown in  FIG. 5 . These magnetic fluxes φ 2  have magnetic effect on the points of contact between the pair of fixed contacts  311 ,  321  and the pair of moving contacts  81 ,  82  in a state where the moving contactor  8  is currently located at the closed position. 
     In the example illustrated in  FIG. 5 , in the internal space of the housing  4 , leftward magnetic fluxes φ 2  are supposed to have been generated, a downward electric current I is supposed to flow through the fixed terminal  31 , and an upward electric current I is supposed to flow through the fixed terminal  32 . When the moving contactor  8  moves from the closed position toward the open position in such a state, an electric discharge current (arc) is generated downward from the fixed contact  311  toward the moving contact  81  between the fixed contact  311  and the moving contact  81 . Thus, the magnetic flux φ 2  applies backward Lorenz force F 2  to the arc (see  FIG. 5 ). As a result, the arc generated between the fixed contact  311  and the moving contact  81  is stretched backward to be extinct. On the other hand, an electric discharge current (arc) is generated upward from the moving contact  82  toward the fixed contact  321  between the fixed contact  321  and the moving contact  82 . Thus, the magnetic flux φ 2  applies forward Lorenz force F 3  to the arc (see  FIG. 5 ). As a result, the arc generated between the fixed contact  321  and the moving contact  82  is stretched forward to be extinct. 
     The housing  4  may be made of a ceramic material such as aluminum oxide (alumina). The housing  4  is formed in the shape of a hollow rectangular parallelepiped, of which the dimension is greater in the rightward/leftward direction than in the forward/backward direction (see  FIG. 1B ). The lower surface of the housing  4  is open. The housing  4  houses the pair of fixed contacts  311 ,  321 , the moving contactor  8 , the first yoke  6 , and the second yoke  7 . The upper surface of the housing  4  has a pair of openings to pass the pair of fixed terminals  31 ,  32  therethrough. The pair of openings may be formed in a circular shape, for example, and runs through the upper wall of the housing  4  along the thickness thereof (i.e., in the upward/downward direction). The fixed terminal  31  is passed through one opening and the fixed terminal  32  is passed through the other opening. The pair of fixed terminals  31 ,  32  and the housing  4  are coupled together by brazing, for example. 
     The housing  4  only needs to be formed in the shape of a box that houses the pair of fixed contacts  311 ,  321  and the moving contactor  8 . Thus, the housing  4  does not have to be formed in the shape of a hollow rectangular parallelepiped as in this embodiment but may also be formed in the shape of a hollow elliptic cylinder or a hollow polygonal column, for example. That is to say, as used herein, the “box shape” refers to any shape in general which has a space to house the pair of fixed contacts  311 ,  321  and the moving contactor  8  inside, and therefore, does not have to be a rectangular parallelepiped shape. Furthermore, the housing  4  does not have to be made of a ceramic material but may also be made of an electrical insulating material such as glass or resin or may even be made of a metallic material. In any case, the housing  4  is suitably made of a non-magnetic material so as not to be magnetized with magnetism and turn into a magnetic body. 
     The flange  5  is made of a non-magnetic metallic material, which may be an austenitic stainless steel such as SUS304. The flange  5  may be formed in the shape of a hollow rectangular parallelepiped elongated in the rightward/leftward direction. The upper and lower surfaces of the flange  5  are open. The flange  5  is arranged between the housing  4  and the electromagnet device  10  (see  FIGS. 1B and 2 ). The flange  5  is hermetically coupled to the housing  4  and a yoke upper plate  111  of the electromagnet device  10  as will be described later. This turns the internal space, surrounded with the housing  4 , the flange  5 , and the yoke upper plate  111 , of the contact device  1  into a hermetically sealed space. The flange  5  does not have to be made of a non-magnetic material but may also be made of an alloy, such as 42 alloy, including iron as a main component. 
     The insulation plate  41  is made of a synthetic resin and has electrical insulation properties. The insulation plate  41  is formed in the shape of a rectangular plate. The insulation plate  41  is located under the moving contactor  8  to electrically insulate the moving contactor  8  from the electromagnet device  10 . The insulation plate  41  has a through hole  42  at a middle portion thereof. In this embodiment, the through hole  42  is aligned with the through hole  83  of the moving contactor  8 . The through hole  42  runs through the insulation plate  41  along the thickness thereof (i.e., in the upward/downward direction). The through hole  42  is provided to pass the shaft  15  therethrough. 
     The spacer  45  is formed in the shape of a cylinder. The spacer  45  may be made of a synthetic resin, for example. The spacer  45  is arranged between the electromagnet device  10  and the insulation plate  41 . The upper end of the spacer  45  is coupled to the lower surface of the insulation plate  41  and the lower end of the spacer  45  is coupled to the electromagnet device  10 . The insulation plate  41  is supported by the spacer  45 . The spacer  45  has a hole to pass the shaft  15  therethrough. 
     The bus bars  21 ,  22  are made of a metallic material with electrical conductivity. The bus bars  21 ,  22  may be made of copper or a copper alloy, for example. The bus bars  21 ,  22  are each formed in the shape of a band. In this embodiment, the bus bars  21 ,  22  are formed by subjecting a metal plate to folding. One end of the bus bar  21  may be electrically connected to the fixed terminal  31  of the contact device  1 , for example. One end of the bus bar  22  may be electrically connected to the fixed terminal  32  of the contact device  1 , for example. 
     The bus bar  21  includes an electrical path piece  211 , which is mechanically connected to the fixed terminal  31 . Specifically, the electrical path piece  211  has a generally square shape in a plan view and is caulked to the fixed terminal  31  at a caulking portion  35  of the fixed terminal  31 . 
     The bus bar  22  includes an electrical path piece  221 , which is mechanically connected to the fixed terminal  32 . Specifically, the electrical path piece  221  has a generally square shape in a plan view and is caulked to the fixed terminal  32  at a caulking portion  36  of the fixed terminal  32 . 
     (1.3) Electromagnet Device 
     Next, a configuration for the electromagnet device  10  will be described. 
     Electromagnet devices  10  are respectively arranged under the contact device  1 A and over the contact device  1 B (see  FIG. 7 ). Specifically, an electromagnet device  10 A is provided under the contact device  1 A and an electromagnet device  10 B is provided over the contact device  1 B. The electromagnetic relay  100 A includes the contact device  1 A and the electromagnet device  10 A. The electromagnetic relay  100 B includes the contact device  1 B and the electromagnet device  10 B. The electromagnet devices  10 A and  10 B have the same configuration and are just inverted in the upward/downward direction and the rightward/leftward direction. Thus, in the following description, only the configuration of the electromagnet device  10 A will be described and description of the electromagnet device  10 B will be omitted herein. 
     As shown in  FIGS. 1A and 1B , the electromagnet device  10 A includes a stator  12 , the mover  13 , and the excitation coil  14 . When the excitation coil  14  is energized, the electromagnet device  10 A has the mover  13  attracted toward the stator  12  by a magnetic field generated by the excitation coil  14 , thereby moving the mover  13  upward. 
     In this embodiment, the electromagnet device  10 A includes not only the stator  12 , the mover  13 , and the excitation coil  14  but also a yoke  11  including the yoke upper plate  111 , the shaft  15 , a cylindrical body  16 , a contact pressure spring  17 , a return spring  18 , and a coil bobbin  19  as well. 
     The stator  12  is a fixed iron core formed in the shape of a cylinder protruding downward from a central region of the lower surface of the yoke upper plate  111 . The upper end of the stator  12  is secured to the yoke upper plate  111 . 
     The mover  13  is a moving iron core also formed in the shape of a cylinder. The mover  13  is arranged under the stator  12  such that the upper end face of the mover  13  faces the lower end face of the stator  12 . The mover  13  is configured to be movable in the upward/downward direction. Specifically, the mover  13  moves from an excitation position where the upper end face thereof is in contact with the lower end face of the stator  12  (see  FIGS. 1B and 2 ) to a non-excitation position where the upper end face thereof is out of contact with the lower end face of the stator  12 , and vice versa. 
     The excitation coil  14  is arranged under the housing  4  such that its center axis is aligned with the upward/downward direction. The stator  12  and the mover  13  are arranged inside the excitation coil  14 . 
     The yoke  11  is arranged to surround the excitation coil  14 . The yoke  11  forms, along with the stator  12  and the mover  13 , a magnetic circuit through which magnetic fluxes pass when the excitation coil  14  is energized. Thus, the yoke  11 , the stator  12 , and the mover  13  are all made of a magnetic material (such as a ferromagnetic body). The yoke upper plate  111  forms part of the yoke  11 . In other words, at least part of the yoke  11  (i.e., the yoke upper plate  111 ) is located between the excitation coil  14  and the moving contactor  8 . 
     The contact pressure spring  17  is arranged between the lower surface of the moving contactor  8  and the upper surface of the insulation plate  41 . The contact pressure spring  17  is a coil spring that biases the moving contactor  8  upward (see  FIG. 1B ). 
     At least part of the return spring  18  is arranged inside the stator  12 . The return spring  18  is a coil spring that biases the mover  13  downward (toward the non-excitation position). One end of the return spring  18  is connected to the upper end face of the mover  13  and the other end of the return spring  18  is connected to the yoke upper plate  111  (see  FIG. 1B ). 
     The shaft  15  is made of a non-magnetic material. The shaft  15  is formed in the shape of a round rod extending in the upward/downward direction. The shaft  15  transmits the driving force, generated by the electromagnet device  10 A, to the contact device  1 A provided over the electromagnet device  10 A. The shaft  15  passes through the through hole  83 , the through hole  71 , the inside of the contact pressure spring  17 , the through hole  42 , the through hole cut through a central region of the yoke upper plate  111 , the inside of the stator  12 , and the inside of the return spring  18  to have the lower end thereof fixed onto the mover  13 . The first yoke  6  is fixed onto the upper end of the shaft  15 . 
     The coil bobbin  19  is made of a synthetic resin. The excitation coil  14  is wound around the coil bobbin  19 . 
     The cylindrical body  16  is formed in the shape of a bottomed cylinder with an open upper surface. The upper end (peripheral portion around the opening) of the cylindrical body  16  is bonded onto the lower surface of the yoke upper plate  111 . This allows the cylindrical body  16  to restrict the direction of movement of the mover  13  to the upward/downward direction and also define the non-excitation position of the mover  13 . The cylindrical body  16  is hermetically bonded onto the lower surface of the yoke upper plate  111 . This allows, even when a through hole is cut through the yoke upper plate  111 , the internal space, surrounded with the housing  4 , the flange  5 , and the yoke upper plate  111 , of the contact device  1 A to be kept sealed hermetically. 
     This configuration allows the moving contactor  8  of the contact device  1 A to move up and down in the upward/downward direction as the mover  13  moves up and down in the upward/downward direction under the driving force generated by the electromagnet device  10 A. 
     (1.4) Electrical Device 
     Next, a configuration for the electrical device  900  will be described. 
     The electrical device  900  includes the two electromagnetic relays  100 A,  100 B and a holding member  920  for holding the electromagnetic relays  100 A,  100 B (see  FIG. 7 ). The holding member  920  may be made of a synthetic resin and formed in the shape of a box, for example. The holding member  920  houses the two electromagnetic relays  100  such that the electromagnetic relays  100  are inverted to each other in the upward/downward direction and the rightward/leftward direction. That is to say, the holding member  920  houses the electromagnetic relays  100 A,  100 B such that the contact device  1 A is located over the electromagnet device  10 A and that the contact device  1 B is located under the electromagnet device  10 B. The holding member  920  further houses the electromagnetic relays  100 A,  100 B such that the electromagnetic relays  100 A,  100 B are arranged side by side in the forward/backward direction. The holding member  920  further holds the electromagnetic relays  100 A,  100 B such that the respective positions of the moving contactor  8  of the contact device  1 A at the closed position and moving contactor  8  of the contact device  1 B at the closed position shift from each other in the direction of movement of the movable contactor  8  (i.e., in the upward/downward direction) (see  FIG. 8 ). Specifically, in the direction of movement (upward/downward direction) of the movable contactor  8 , the movable contactor  8  of the contact device  1 A at the closed position is arranged between the yoke upper plate  111  of the electromagnet device  10 B and the movable contactor  8  of the contact device  1 B at the closed position. Furthermore, in the direction of movement of the movable contactor  8  (in the upward/downward direction), the movable contactor  8  of the contact device  1 B at the closed position is arranged between the yoke upper plate  111  of the electromagnet device  10 A and the movable contactor  8  of the contact device  1 A at the closed position. 
     Alternatively, in the direction of movement of the movable contactor  8  (in the upward/downward direction), the movable contactor  8  of the contact device  1 A at the closed position may be arranged under the yoke upper plate  111  of the electromagnet device  10 B. Also, in the direction of movement of the movable contactor  8  (in the upward/downward direction), the movable contactor  8  of the contact device  1 B at the closed position may be arranged over the yoke upper plate  111  of the electromagnet device  10 A. 
     In this embodiment, in the contact device  1 A, the electric current I 1  is supposed to be input to the fixed terminal  31  and the input electric current I 1  is supposed to be output from the fixed terminal  32  via the movable contactor  8  as shown in  FIG. 6 . On the other hand, in the contact device  1 B, the electric current I 2  is supposed to be input to the fixed terminal  32  and the input electric current I 2  is supposed to be output from the fixed terminal  31  via the movable contactor  8 . That is to say, the contact devices  1 A and  1 B are arranged so as to be inverted in the rightward/leftward direction. Thus, the direction of the electric current I 1  flowing through the movable contactor  8  of the contact device  1 A (i.e., the rightward direction) and the direction of the electric current I 2  flowing through the movable contactor  8  of the contact device  1 B (i.e., the leftward direction) become opposite from each other. 
     As described above, the contact device  1 A and the contact device  1 B are connected to the common path along which DC power is supplied from the battery E 1  to the load R 1 . The electromagnet devices  10 A,  10 B are configured such that the respective movable contactors  8  of the contact devices  1 A,  1 B move in sync with each other. That is to say, when the movable contactor  8  of the contact device  1 A is currently located at the closed position, the movable contactor  8  of the contact device  1 B is also located at the closed position. When the movable contactor  8  of the contact device  1 A is currently located at the open position, the movable contactor  8  of the contact device  1 B is also located at the open position. Thus, the amount of electric current I flowing through the movable contactor  8  of the contact device  1 A becomes equal to the amount of electric current I 2  flowing through the movable contactor  8  of the contact device  1 B. 
     (2) Operation 
     Next, it will be described briefly how the electromagnetic relay  100 A, including the contact device  1 A and electromagnet device  10 A with such configurations, operates. The electromagnetic relay  100 B operates in the same way as the electromagnetic relay  100 A, and therefore, description thereof will be omitted herein. 
     While the excitation coil  14  is supplied with no electric current (i.e., not energized), no magnetic attractive force is generated between the mover  13  and the stator  12 . Thus, in such a situation, the mover  13  is located at the non-excitation position under the spring force applied by the return spring  18 . At this time, the shaft  15  has been pulled down to restrict the upward movement of the moving contactor  8 . This causes the moving contactor  8  to be located at the open position, which is lower end position of its movable range. This brings the pair of moving contacts  81 ,  82  out of contact with the pair of fixed contacts  311 ,  321 , thus turning the contact device  1  open. In this state, the pair of fixed terminals  31 ,  32  are not electrically conductive with each other. 
     On the other hand, when the excitation coil  14  is energized (i.e., supplied with an electric current), magnetic attractive force is generated between the mover  13  and the stator  12 , thus causing the mover  13  to be pulled upward by overcoming the spring force applied by the return spring  18  to reach the excitation position. At this time, the shaft  15  is pushed upward, thus canceling the shaft&#39;s  15  restriction on the upward movement of the moving contactor  8 . Then, the contact pressure spring  17  biases the moving contactor  8  upward, thus causing the moving contactor  8  to move toward the closed position at the upper end of its movable range. This brings the pair of moving contacts  81 ,  82  into contact with the pair of fixed contacts  311 ,  321 , thus turning the contact device  1  closed. In this state, the contact device  1  is closed, and therefore, the pair of fixed terminals  31 ,  32  are electrically conductive with each other. 
     This allows the electromagnet device  10  to control the attractive force to be applied onto the mover  13  by selectively energizing the excitation coil  14  and to generate driving force for changing the state of the contact device  1  from the open state to the closed state, and vice versa, by moving the mover  13  up and down in the upward/downward direction. 
     (3) Advantages 
     When the excitation coil  14  is energized (or supplied with an electric current), the mover  13  moves from the non-excitation position to the excitation position in the electromagnet device  10  as described above. At this time, the driving force generated by the electromagnet device  10  causes the moving contactor  8  to move from the open position toward the closed position. This brings the moving contacts  81 ,  82  into contact with the fixed contacts  311 ,  321 , thus turning the contact device  1  closed. When the contact device  1  is closed, the contact pressure spring  17  presses the moving contacts  81 ,  82  against the fixed contacts  311 ,  321 , respectively. 
     In some cases, when the contact device  1  is closed, electromagnetic repulsion that brings the moving contacts  81 ,  82  out of contact with the fixed contacts  311 ,  321  may be caused by an electric current flowing through the contact device  1  (between the fixed terminals  31 ,  32 ) That is to say, when an electric current flows through the contact device  1 , the Lorenz force sometimes causes the electromagnetic repulsion to the moving contactor  8  in such a direction as to move the moving contactor  8  from the closed position toward the open position (i.e., downward). The electromagnetic repulsion is ordinarily less than the spring force applied by the contact pressure spring  17 , thus allowing the moving contactor  8  to keep the moving contacts  81 ,  82  in contact with the fixed contacts  311 ,  321 . Nevertheless, when a significant amount of electric current (of about 6 kA, for example) such as a short-circuit current flows (as an abnormal electric current) through the contact device  1 , the electromagnetic repulsion applied to the moving contactor  8  could be greater than the spring force applied by the contact pressure spring  17 . In this embodiment, an electric current flowing through the respective moving contactors  8  of the contact devices  1 A,  1 B is used as a countermeasure against such electromagnetic repulsion. 
     In the contact module  91  according to this embodiment, the direction in which the electric current I 1  flows through the moving contactor  8  of the contact device  1 A and the direction in which the electric current I 2  flows through the moving contactor  8  of the contact device  1 B become opposite from each other. Thus, when an abnormal electric current such as a short-circuit current flows through the contact devices  1 A,  1 B, repulsive forces F 11 , F 12  are produced between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B (see  FIG. 8 ). As used herein, the “repulsive forces F 11 , F 12 ” refer to forces applied in mutually opposite directions, among the forces interacting between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. Such repulsive forces F 11 , F 12  are forces that the electric current I 1  flowing through the moving contactor  8  of the contact device  1 A and the electric current I 2  flowing through the moving contactor  8  of the contact device  1 B receive under the Lorenz force. 
     When the respective moving contactors  8  of the contact devices  1 A and  1 B are each located at the closed position, the moving contactor  8  of the contact device  1 A is located, in the direction of movement of the moving contactors  8 , between the fixed terminals  31 ,  32  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. On the other hand, when the respective moving contactors  8  of the contact devices  1 A and  1 B are each located at the closed position, the moving contactor  8  of the contact device  1 B is located, in the direction of movement of the moving contactors  8 , between the fixed terminals  31 ,  32  of the contact device  1 B and the moving contactor  8  of the contact device  1 A. The respective moving contactors  8  of the contact devices  1 A,  1 B are movable in the upward/downward direction. The repulsive forces produced between the respective moving contactors  8  of the contact devices  1 A,  1 B cause the forces F 11 , F 12  to be applied to the respective moving contactors  8  of the contact devices  1 A,  1 B (see  FIG. 8 ). Out of force components F 11   x  and F 11   y , respectively produced in the upward/downward direction and the forward/backward direction, of the force F 11 , the force component F 11   x  is applied to the moving contactor  8  of the contact device  1 A. On the other hand, out of force components F 12   x  and F 12   y , respectively produced in the upward/downward direction and the forward/backward direction, of the force F 12 , the force component F 12   x  is applied to the moving contactor  8  of the contact device  1 B. 
     Thus, force in the direction from the open position toward the closed position (i.e., upward force) is applied to the moving contactor  8  of the contact device  1 A by the magnetic field generated by the moving contactor  8  of the contact device  1 B. On the other hand, force in the direction from the open position toward the closed position (i.e., downward force) is applied to the moving contactor  8  of the contact device  1 B by the magnetic field generated by the moving contactor  8  of the contact device  1 A. This increases the force with which the moving contactor  8  is pressed against the fixed contacts  311 ,  312  in each of the contact devices  1 A,  1 B. 
     This increases, even when an abnormal electric current such as a short-circuit current flows through each of the contact devices  1 A,  1 B, the stability of connection between the moving contacts  81 ,  82  and fixed contacts  311 ,  321  in each of the contact devices  1 A,  1 B. 
     (4) Variations 
     In a contact module  91   a  according to a variation, the relative positions of the contact devices  1 A and  1 B are different from those of the contact module  91  described above. 
     Specifically, according to this variation, the contact devices  1 A,  1 B are laid one on of the other in the upward/downward direction (see  FIG. 9 ). The contact device  1 B is arranged over the contact device  1 A so as to be inverted both in the upward/downward direction and the rightward/leftward direction with respect to the contact device  1 A. Therefore, the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B face each other in the upward/downward direction. 
     In this variation, in the contact device  1 A, the electric current I 1  is supposed to be input to the fixed terminal  31  and the input electric current I 1  is supposed to be output through the fixed terminal  32  via the moving contactor  8 . On the other hand, in the contact device  1 B, the electric current I 2  is supposed to be input to the fixed terminal  32  and the input electric current I 2  is supposed to be output through the fixed terminal  31  via the moving contactor  8 . That is to say, the direction of the electric current I 1  flowing through the moving contactor  8  of the contact device  1 A (i.e., the rightward direction) and the direction of the electric current I 2  flowing through the moving contactor  8  of the contact device  1 B (i.e., the rightward direction) are the same (see  FIG. 10 ). 
     Thus, the Lorenz force produces attractive force between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. Specifically, the moving contactor  8  of the contact device  1 A is subjected to force F 21  applied in the direction from the open position toward the closed position (i.e., the upward direction) by the magnetic field generated by the moving contactor  8  of the contact device  1 B. On the other hand, the moving contactor  8  of the contact device  1 B is subjected to force F 22  applied in the direction from the open position toward the closed position (i.e., the downward direction) by the magnetic field generated by the moving contactor  8  of the contact device  1 A. As a result, in each of the contact devices  1 A,  1 B, the force with which the moving contactor  8  is pressed against the fixed contact  311 ,  321  increases. This reduces, even when a large amount of current flows between the fixed terminals  31 ,  32  in each of the contact devices  1 A,  1 B, the chances of the electromagnetic repulsion bringing the pair of fixed contacts  311 ,  321  out of contact with the pair of moving contacts  81 ,  82 . 
     Second Embodiment 
     A contact module  91   b  according to a second embodiment includes the contact devices  1 A,  1 B, and a magnetic shield member  9  (see  FIG. 11 ). 
     As in the contact module  91  according to the first embodiment, the contact devices  1 A and  1 B are arranged side by side in the forward/backward direction, and the contact device  1 B is arranged so as to be inverted both in the upward/downward direction and the rightward/leftward direction with respect to the contact device  1 A. 
     The magnetic shield member  9  is made of a magnetic material (such as magnetic steel) and formed in the shape of a rectangular plate. The magnetic shield member  9  is arranged to have its thickness aligned with the forward/backward direction to separate the contact device  1 A from the contact device  1 B. 
     The magnetic shield member  9  reduces the force applied in the direction from the closed position toward the open position to the respective moving contactors  8  of the contact devices  1 A and  1 B. In this embodiment, in the contact device  1 A, the electric current I 1  is supposed to be input to the fixed terminal  31  and the input electric current I 1  is supposed to be output through the fixed terminal  32  via the moving contactor  8 . On the other hand, in the contact device  1 B, the electric current I 2  is supposed to be input to the fixed terminal  32  and the input electric current I 2  is supposed to be output through the fixed terminal  31  via the moving contactor  8 . That is to say, the direction of the electric current I 1  flowing through the moving contactor  8  of the contact device  1 A (i.e., the rightward direction) and the direction of the electric current I 2  flowing through the moving contactor  8  of the contact device  1 B (i.e., the rightward direction) are the same (see  FIG. 11 ). 
     Thus, the Lorenz force produces attractive forces between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. These attractive forces cause forces F 31 , F 32  to be applied to the respective moving contactors  8  of the contact devices  1 A,  1 B. The respective moving contactors  8  of the contact devices  1 A,  1 B are movable in the upward/downward direction. Thus, out of a force component F 31   x  in the upward/downward direction and a force component F 31   y  in the forward/backward direction of the force F 31 , the force component F 31   x  is applied to the moving contactor  8  of the contact device  1 A. On the other hand, out of a force component F 32   x  in the upward/downward direction and a force component F 32   y  in the forward/backward direction of the force F 32 , the force component F 32   x  is applied to the moving contactor  8  of the contact device  1 B. That is to say, the moving contactor  8  of the contact device  1 A is subjected to the force applied in the direction from the closed position toward the open position (i.e., in the downward direction) by the magnetic field generated by the moving contactor  8  of the contact device  1 B. Meanwhile, the moving contactor  8  of the contact device  1 B is subjected to the force applied in the direction from the closed position toward the open position (i.e., in the upward direction) by the magnetic field generated by the moving contactor  8  of the contact device  1 A. 
     The magnetic shield member  9  is arranged such that its thickness is perpendicular to the direction of movement of the moving contactors  8  (i.e., the upward/downward direction) (such that its thickness is defined in the forward/backward direction) and that its position in the forward/backward direction is between the contact devices  1 A and  1 B. Specifically, the magnetic shield member  9  is arranged at a position between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. As used herein, the position between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B includes at least a position between the upper end of the moving contactor  8  of the contact device  1 A at the closed position and the lower end of the moving contactor  8  of the contact device  1 B at the closed position in the direction of movement of the moving contactors  8  (i.e., the upward/downward direction). In this embodiment, the magnetic shield member  9  is arranged so as to overlap with (i.e., hide) the electromagnetic relays  100 A,  100 B in their entirety when viewed in the forward/backward direction. The magnetic shield member  9  may have its position fixed by being fitted into a groove cut on the holding member  920  (see  FIG. 7 ), for example. 
     The magnetic shield member  9  reduces the magnetic field applied from the moving contactor  8  of the contact device  1 A to the moving contactor  8  of the contact device  1 B and also reduces the magnetic field applied from the moving contactor  8  of the contact device  1 B to the moving contactor  8  of the contact device  1 A. This reduces the magnetic flux passing through the respective moving contactors  8  of the contact devices  1 A,  1 B. Consequently, this reduces the force applied in the direction from the closed position toward the open position to the moving contactor  8  of the contact device  1 B by the magnetic field generated by the moving contactor  8  of the contact device  1 A. This also reduces the force applied in the direction from the closed position toward the open position to the moving contactor  8  of the contact device  1 A by the magnetic field generated by the moving contactor  8  of the contact device  1 B. This increases, when the respective moving contactors  8  of the contact devices  1 A,  1 B are located at the closed position, the stability of connection between the pair of moving contacts  81 ,  82  and the pair of fixed contacts  311 ,  321 . 
     Note that the magnetic shield member  9  only needs to have magnetic properties, and therefore, does not have to be configured as a ferromagnetic body alone but may include an additional member as well. For example, the magnetic shield member  9  may also be formed by coating a ferromagnetic body with a synthetic resin or any other suitable material. In addition, the magnetic shield member  9  does not have to be configured as a flat plate but may also be formed in the shape of a net, for example. 
     (Variations) 
     In a contact module  91   c  according to a variation, the relative positions of the contact devices  1 A and  1 B are different from those of the contact module  91   b  described above (see  FIG. 12 ). 
     Specifically, in this variation, the contact devices  1 A,  1 B are arranged to be laid one on top of the other in the upward/downward direction as in the contact module  91   a  according to the variation of the first embodiment. The contact device  1 B is arranged over the contact device  1 A so as to be inverted both in the upward/downward direction and the rightward/leftward direction with respect to the contact device  1 A. Therefore, the respective moving contactors  8  of the contact devices  1 A,  1 B face each other in the upward/downward direction. 
     The magnetic shield member  9  is arranged between the respective moving contactors  8  of the contact devices  1 A,  1 B so as to have its thickness aligned with the upward/downward direction and to separate the contact devices  1 A,  1 B from each other. In this variation, the magnetic shield member  9  is formed to overlap with (i.e., hide) the electromagnetic relays  100 A,  100 B in their entirety when viewed in the upward/downward direction. 
     In this variation, in the contact device  1 A, the electric current I 1  is supposed to be input to the fixed terminal  31  and the input electric current I 1  is supposed to be output through the fixed terminal  32  via the moving contactor  8 . On the other hand, in the contact device  1 B, the electric current I 2  is supposed to be input to the fixed terminal  31  and the input electric current I 2  is supposed to be output through the fixed terminal  32  via the moving contactor  8 . That is to say, the direction of the electric current I 1  flowing through the moving contactor  8  of the contact device  1 A (i.e., the rightward direction) and the direction of the electric current I 2  flowing through the moving contactor  8  of the contact device  1 B (i.e., the leftward direction) are opposite from each other. 
     Thus, repulsive forces F 41 , F 42  are produced between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. Specifically, the moving contactor  8  of the contact device  1 A is subjected to the force F 41  applied in the direction from the closed position toward the open position (i.e., the downward direction) by the magnetic field generated by the moving contactor  8  of the contact device  1 B. On the other hand, the moving contactor  8  of the contact device  1 B is subjected to the force F 42  applied in the direction from the closed position toward the open position (i.e., the upward direction) by the magnetic field generated by the moving contactor  8  of the contact device  1 A. 
     A magnetic shield member  9  is arranged between the respective moving contactors  8  of the contact devices  1 A,  1 B. The magnetic shield member  9  reduces the magnetic field applied from the moving contactor  8  of the contact device  1 A to the moving contactor  8  of the contact device  1 B and also reduces the magnetic field applied from the moving contactor  8  of the contact device  1 B to the moving contactor  8  of the contact device  1 A. This reduces the force applied in the direction from the closed position toward the open position to the moving contactor  8  of the contact device  1 B by the magnetic field generated by the moving contactor  8  of the contact device  1 A. This also reduces the force applied in the direction from the closed position toward the open position to the moving contactor  8  of the contact device  1 A by the magnetic field generated by the moving contactor  8  of the contact device  1 B. This increases, when the respective moving contactors  8  of the contact devices  1 A,  1 B are located at the closed position, the stability of connection between the pair of moving contacts  81 ,  82  and the pair of fixed contacts  311 ,  321 . 
     (Other Variations) 
     Other variations will be enumerated one after another. Any of the variations to be described below may be combined as appropriate with the embodiments described above (including the variations thereof). 
     In the exemplary embodiments described above and variations thereof, the contact devices  1 A,  1 B have the same configuration. However, this is only an example and should not be construed as limiting. Alternatively, the contact devices  1 A,  1 B may have mutually different configurations. 
     In the exemplary embodiments described above, the housing  4  is configured to partially expose the fixed terminals  31 ,  32 . However, this is only an example and should not be construed as limiting. Alternatively, the housing  4  may house the fixed terminals  31 ,  32  entirely inside itself. That is to say, the housing  4  only needs to be configured to house the fixed contacts  311 ,  321  and the moving contactor  8  to say the least. 
     Also, in the exemplary embodiments described above, the contact device may include no capsule yokes. When provided, the capsule yokes could weaken the repulsive or attractive forces between the moving contactor  8  of the contact device  1 A and the moving contactor  8  of the contact device  1 B. Thus, removing the capsule yokes curbs such a decrease in repulsive or attractive forces due to the presence of capsule yokes, thus eventually increasing the force with which the moving contactor  8  is pressed against the fixed contacts  311 ,  321 . 
     Furthermore, in the exemplary embodiment described above, each electromagnetic relay is supposed to be a so-called “normally OFF” electromagnetic relay, of which the moving contactor  8  is located at the open position while the excitation coil  14  is not energized. However, this is only an example and should not be construed as limiting. Alternatively, each electromagnetic relay may also be a normally ON electromagnetic relay. 
     Furthermore, in the exemplary embodiments described above, the number of moving contacts held by the moving contactor  8  is two. However, this is only an example and should not be construed as limiting. The number of the moving contacts held by the moving contactor  8  may also be one or even three or more. Likewise, the number of the fixed terminals (and fixed contacts) does not have to be two but may also be one or even three or more. 
     The electromagnetic relay according to the exemplary embodiments is implemented as an electromagnetic relay with no holders. However, this is only an example and should not be construed as limiting. Alternatively, the electromagnetic relay may also be implemented as an electromagnetic relay with a holder. In that case, the holder may have the shape of a rectangular cylinder with the right and left end faces open and may be combined with the moving contactor  8  such that the moving contactor  8  runs through the holder in the rightward/leftward direction. The contact pressure spring  17  is arranged between the lower wall of the holder and the moving contactor  8 . That is to say, the moving contactor  8  is held by the holder at a central region thereof in the rightward/leftward direction. The upper end of the shaft  15  is secured to the holder. When the excitation coil  14  is energized, the shaft  15  is pushed upward, and therefore, the holder moves upward. This movement causes the moving contactor  8  to move upward, thereby bringing the pair of moving contacts  81 ,  82  to the closed position where the pair of moving contacts  81 ,  82  are in contact with the pair of fixed contacts  311 ,  321 . 
     Furthermore, in the exemplary embodiments described above, the contact device is implemented as a plunger type contact device. Alternatively, the contact device may also be implemented as a hinged contact device. 
     Furthermore, in the exemplary embodiments described above, the bus bar  21 ,  22  is caulked to, and thereby mechanically connected to, the fixed terminals  31 ,  32 . However, this is only an example and should not be construed as limiting. Alternatively, the bus bar  21 ,  22  may also be mechanically connected with screws onto the fixed terminals  31 ,  32 . Still alternatively, the bus bar may also be coupled to the fixed terminals  31 ,  32  by welding, brazing, or any other suitable method. 
     Furthermore, in the exemplary embodiments described above, the arc extinction magnets are arranged outside the housing  4  (i.e., between the capsule yokes and the housing  4 ). 
     However, this is only an example and should not be construed as limiting. Alternatively, the arc extinction magnets may also be arranged inside the housing  4 . 
     Furthermore, none of the yokes, arc extinction magnets, and capsule yokes is an essential constituent element for the contact device according to any of the exemplary embodiments. 
     (Resume) 
     A contact module ( 91 ,  91   a ) according to a first aspect includes a pair of contact devices ( 1 ,  1 A,  1 B), which consists of one contact device ( 1 A) and the other contact device ( 1 B). The one contact device ( 1 A) includes one fixed terminal ( 31 ,  32 ) and one moving contactor ( 8 ). The one fixed terminal ( 31 ,  32 ) has one fixed contact ( 311 ,  321 ). The one moving contactor ( 8 ) has one moving contact ( 81 ,  82 ) and moves from a closed position where the one moving contact ( 81 ,  82 ) is in contact with the one fixed contact ( 311 ,  321 ) to an open position where the one moving contact ( 81 ,  82 ) is out of contact with the one fixed contact ( 311 ,  321 ), and vice versa. The other contact device ( 1 B) includes the other fixed terminal ( 31 ,  32 ) and the other moving contactor ( 8 ). The other fixed terminal ( 31 ,  32 ) has the other fixed contact ( 311 ,  321 ). The other moving contactor ( 8 ) has the other moving contact ( 81 ,  82 ) and moves from a closed position where the other moving contact ( 81 ,  82 ) is in contact with the other fixed contact ( 311 ,  321 ) to an open position where the other moving contact ( 81 ,  82 ) is out of contact with the other fixed contact ( 311 ,  321 ), and vice versa. The pair of contact devices ( 1 ,  1 A,  1 B) is arranged such that a direction in which the one moving contactor ( 8 ) of the one contact device ( 1 A) moves from the open position toward the closed position and a direction in which the other moving contactor ( 8 ) of the other contact device ( 1 B) moves from the open position toward the closed position are opposite from each other. The one moving contactor ( 8 ) generates, when energized, a magnetic field that applies force, in a direction from the open position of the other moving contactor ( 8 ) toward the closed position of the other moving contactor ( 8 ), to the other moving contactor ( 8 ), through which an electric current is flowing. The other moving contactor ( 8 ) generates, when energized, a magnetic field that applies force, in a direction from the open position of the one moving contactor ( 8 ) toward the closed position of the one moving contactor ( 8 ), to the one moving contactor ( 8 ), through which an electric current is flowing. 
     This aspect allows the magnetic field generated by the one moving contactor ( 8 ) to increase the force with which the other moving contactor ( 8 ) presses the other fixed contact ( 311 ,  312 ) and also allows the magnetic field generated by the other moving contactor ( 8 ) to increase the force with which the one moving contactor ( 8 ) presses the one fixed contact ( 311 ,  312 ). This increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     In a contact module ( 91 ) according to a second aspect, which may be implemented in conjunction with the first aspect, the one moving contactor ( 8 ) and the other moving contactor ( 8 ) are located, in their direction of movement, between the one fixed contact ( 311 ,  321 ) of the one contact device ( 1 A) and the other fixed contact ( 311 ,  321 ) of the other contact device ( 1 B), and have respectively different closed positions. A direction in which the electric current flows through the one moving contactor ( 8 ) and a direction in which the electric current flows through the other moving contactor ( 8 ) are opposite from each other. 
     This aspect allows repulsive forces produced between the one moving contactor ( 8 ) and the other moving contactor ( 8 ) to increase the force with which the one moving contactor ( 8 ) presses the one fixed contact ( 311 ,  321 ) and also increase the force with which the other moving contactor ( 8 ) presses the other fixed contact ( 311 ,  321 ). This increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     In a contact module ( 91   a ) according to a third aspect, which may be implemented in conjunction with the first aspect, the one moving contactor ( 8 ) and the other moving contactor ( 8 ) have, in their direction of movement, respectively different closed positions. The one fixed contact ( 311 ,  321 ) of the one contact device ( 1 A) and the other fixed contact ( 311 ,  321 ) of the other contact device ( 1 B) are located, in respective directions of movement of the one moving contactor ( 8 ) and the other moving contactor ( 8 ), between the one moving contactor ( 8 ) and the other moving contactor ( 8 ). A direction in which the electric current flows through the one moving contactor ( 8 ) and a direction in which the electric current flows through the other moving contactor ( 8 ) are the same. 
     This aspect allows the attractive force produced between the one moving contactor ( 8 ) and the other moving contactor ( 8 ) to increase the force with which the one moving contactor ( 8 ) presses the one fixed contact ( 311 ,  321 ) and also increase the force with which the other moving contactor ( 8 ) presses the other fixed contact ( 311 ,  321 ). This increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     A contact module ( 91   b ,  91   c ) according to a fourth aspect includes: a pair of contact devices ( 1 ,  1 A,  1 B) consisting of one contact device ( 1 A) and the other contact device ( 1 B); and a magnetic shield member ( 9 ) having magnetic properties. The one contact device ( 1 A) includes one fixed terminal ( 31 ,  32 ) and one moving contactor ( 8 ). The one fixed terminal ( 31 ,  32 ) has one fixed contact ( 311 ,  321 ). The one moving contactor ( 8 ) has one moving contact ( 81 ,  82 ) and moves from a closed position where the one moving contact ( 81 ,  82 ) is in contact with the one fixed contact ( 311 ,  321 ) to an open position where the one moving contact ( 81 ,  82 ) is out of contact with the one fixed contact ( 311 ,  321 ), and vice versa. The other contact device ( 1 B) includes the other fixed terminal ( 31 ,  32 ) and the other moving contactor ( 8 ). The other fixed terminal ( 31 ,  32 ) has the other fixed contact ( 311 ,  321 ). The other moving contactor ( 8 ) has the other moving contact ( 81 ,  82 ) and moves from a closed position where the other moving contact ( 81 ,  82 ) is in contact with the other fixed contact ( 311 ,  321 ) to an open position where the other moving contact ( 81 ,  82 ) is out of contact with the other fixed contact ( 311 ,  321 ), and vice versa. The pair of contact devices ( 1 ,  1 A,  1 B) are arranged such that a direction in which the one moving contactor ( 8 ) of the one contact device ( 1 A) moves from the open position toward the closed position and a direction in which the other moving contactor ( 8 ) of the other contact device ( 1 B) moves from the open position toward the closed position are opposite from each other. The one moving contactor ( 8 ) generates, when energized, a magnetic field that applies force, in a direction from the closed position of the other moving contactor ( 8 ) toward the open position of the other moving contactor ( 8 ), to the other moving contactor ( 8 ), through which an electric current is flowing. The other moving contactor ( 8 ) generates, when energized, a magnetic field that applies force, in a direction from the closed position of the one moving contactor ( 8 ) toward the open position of the one moving contactor ( 8 ), to the one moving contactor ( 8 ), through which an electric current is flowing. The magnetic shield member ( 9 ) is arranged between the one moving contactor ( 8 ) and the other moving contactor ( 8 ). 
     This aspect allows the magnetic shield member ( 9 ) to weaken the magnetic field applied from the one moving contactor ( 8 ) to the other moving contactor ( 8 ) and also weaken the magnetic field applied from the other moving contactor ( 8 ) to the one moving contactor ( 8 ), thus reducing the force applied to the one moving contactor ( 8 ) and the other moving contactor ( 8 ) in a direction from the closed position toward the open position. This increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     In a contact module ( 91 ,  91   a ,  91   b ,  91   c ) according to a fifth aspect, which may be implemented in conjunction with any one of the first to fourth aspects, in each of the one contact device ( 1 A) and the other contact device ( 1 B), each of the one and the other fixed terminals ( 31 ,  32 ) includes a first fixed terminal ( 31 ) and a second fixed terminal ( 32 ). Each of the one and the other fixed contacts ( 311 ,  321 ) includes: a first fixed contact ( 311 ) provided for the first fixed terminal ( 31 ); and a second fixed contact ( 321 ) provided for the second fixed terminal ( 32 ). Each of the one and the other moving contacts ( 81 ,  82 ) includes a first moving contact ( 81 ) and a second moving contact ( 82 ) to come into contact with the first fixed contact ( 311 ) and the second fixed contact ( 321 ), respectively, when the one or the other moving contactor ( 8 ) is located at the closed position. 
     This aspect increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     A contact device ( 1 ,  1 A,  1 B) according to a sixth aspect is included in the contact module ( 91 ,  91   a ,  91   b ,  91   c ) according to any one of the first to fifth aspects. 
     This aspect increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the contact devices ( 1 ,  1 A,  1 B). 
     An electromagnetic relay module ( 910 ) according to a seventh aspect includes: the contact module ( 91 ,  91   a ,  91   b ,  91   c ) according to any one of the first to fifth aspects; and a pair of electromagnet devices ( 10 ,  10 A,  10 B) consisting of one electromagnet device ( 10 A) and the other electromagnet device ( 10 B). The one electromagnet device ( 10 A) moves the one moving contactor ( 8 ), while the other electromagnet device ( 10 B) moves the other moving contactor ( 8 ). 
     This aspect increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     An electrical device ( 900 ) according to an eighth aspect includes: the electromagnetic relay module ( 910 ) according to the seventh aspect; and a holding member ( 920 ). The holding member ( 920 ) holds the electromagnetic relay module ( 910 ) such that a direction in which the one moving contactor ( 8 ) moves from the open position toward the closed position and a direction in which the other moving contactor ( 8 ) moves from the open position toward the closed position are opposite from each other. 
     This aspect increases the stability of connection between the moving contact ( 81 ,  82 ) and the fixed contact ( 311 ,  321 ) in each of the one contact device ( 1 A) and the other contact device ( 1 B). 
     Note that the constituent elements according to the second, third, and fifth aspects are not essential constituent elements for the contact module ( 91 ,  91   a ,  91   b ,  91   c ) but may be omitted as appropriate. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Contact Device 
               1 A (One) Contact Device 
               1 B (the Other) Contact Device 
               31  Fixed Terminal (First Fixed Terminal) 
               311  Fixed Contact (First Fixed Contact) 
               32  Fixed Terminal (Second Fixed Terminal) 
               321  Fixed Contact (Second Fixed Contact) 
               8  Moving Contactor 
               81  Moving Contact (First Moving Contact) 
               82  Moving Contact (Second Moving Contact) 
               9  Magnetic Shield Member 
               91 ,  91   a ,  91   b ,  91   c  Contact Module 
               910  Electromagnetic Relay Module 
               10 ,  10 A,  10 B Electromagnet Device 
               900  Electrical Device 
               920  Holding Member