Patent Publication Number: US-11031203-B2

Title: Contact point device and electromagnetic relay

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2017/039651 filed on Nov. 2, 2017. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2017-006932 filed on Jan. 18, 2017. The entire disclosures of all of the above applications are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a contact point device and an electromagnetic relay. 
     BACKGROUND ART 
     A contact point device described in Patent Document 1 includes two fixed contact points, and a movable contactor having two movable contact points. A slit is formed in one of the movable contact points. The fixed contact point corresponding to the one of the movable contact points comes into contact with the one of the movable contact points at both sides of the slit. As a result, the contact state between the movable contactor and the fixed contact point is stabilized. 
     PRIOR ART DOCUMENTS 
     Patent Document 
     
         
         Patent Document 1: JP 2012-199117 A 
       
    
     SUMMARY 
     This type of device is used, for example, in an electric vehicle such as a hybrid vehicle, for switching on or off an electric circuit between a motor drive circuit and a battery. In recent electric vehicles, the current between the motor drive circuit and the battery tends to increase as the running performance improves. Therefore, in this type of device, it is required to further reduce the contact resistance between the contact points. The present disclosure has been made in view of the circumstances exemplified above, and it is an object thereof to provide a contact point device and an electromagnetic relay. 
     In one aspect of the present disclosure, the contact point device is configured to switch an electric current to flow or not by relative movement between a movable portion and a fixed portion. 
     The contact point device includes: 
     a first contactor provided on one of the movable portion and the fixed portion as a conductive contact member having an outer side surface shaped in a column that surrounds a central axis along a relative movement direction of the movable portion and the fixed portion; 
     an oscillation supporting portion that supports the first contactor at the one of the movable portion and the fixed portion to allow the central axis to oscillate; and 
     a second contactor provided on the other of the movable portion and the fixed portion as a conductive contact member disposed opposite to the first contactor in the relative movement direction so as to be electrically connected to the first contactor by abutting against the first contactor. 
     One of the first contactor and the second contactor includes a plurality of first contact portions. The plurality of first contact portions are provided to surround the central axis on a plane orthogonal to the central axis. 
     The other of the first contactor and the second contactor, which is different from the one of the first contactor and the second contactor, includes a second contact portion. The second contact portion protrudes in the relative movement direction toward a space surrounded by the plurality of first contact portions. 
     The second contact portion has a contact surface which is a curved surface exposed toward the space to surround the central axis. 
     In another aspect of the present disclosure, an electromagnetic relay is configured to switch an electric current to flow or not by a movement of a movable portion relative to a fixed portion in a coil axis direction based on an energization state of a coil. 
     The electromagnetic relay includes: 
     a first contactor provided on one of the movable portion and the fixed portion as a conductive contact member having an outer side surface shaped in a column that surrounds a central axis along the coil axis direction; 
     an oscillation supporting portion that supports the first contactor at the one of the movable portion and the fixed portion to allow the central axis to oscillate; and 
     a second contactor provided on the other of the movable portion and the fixed portion as a conductive contact member disposed opposite to the first contactor in the coil axis direction so as to be electrically connected to the first contactor by abutting against the first contactor. 
     One of the first contactor and the second contactor includes a plurality of first contact portions. The plurality of first contact portions are provided to surround the central axis on a plane perpendicular to the central axis. 
     The other of the first contactor and the second contactor, which is different from the one of the first contactor and the second contactor, includes a second contact portion. The second contact portion protrudes in the coil axis direction toward a space surrounded by the plurality of first contact portions. 
     The second contact portion has a contact surface which is a curved surface exposed toward the space to surround the central axis. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view illustrating a schematic configuration of an electromagnetic relay and a contact point device according to an embodiment. 
         FIG. 2  is an enlarged perspective view illustrating a part of the contact point device shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the contact point device shown in  FIG. 2 . 
         FIG. 4  is an enlarged bottom view illustrating a periphery of the first contact portion shown in  FIG. 2 . 
         FIG. 5  is a perspective view illustrating a schematic configuration of a contact point device according to a modification of the embodiment. 
         FIG. 6  is a bottom view or a plan view illustrating a second contactor shown in  FIG. 5 . 
         FIG. 7  is a perspective view illustrating a schematic configuration of a contact point device of another modification of the embodiment. 
         FIG. 8  is a side view illustrating a first contactor and an oscillation supporting portion shown in  FIG. 7 ; 
         FIG. 9  is a plan view or a bottom view of the first contactor and the oscillation supporting portion shown in  FIG. 8 . 
         FIG. 10  is a cross-sectional view illustrating a schematic configuration of an electromagnetic relay and a contact point device according to another modification of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present disclosure is described with reference to the drawings. Various modifications applicable to the embodiment will be collectively described as modifications after the description of the embodiment. 
     (Schematic Configuration of Electromagnetic Relay) 
     The schematic configuration of the electromagnetic relay  1  according to the embodiment will be described with reference to  FIG. 1 . The electromagnetic relay  1  includes a housing  2 , a frame  3 , a coil  4 , a fixed portion  5 , and a movable portion  6 .  FIG. 1  shows a state in which the coil  4  is not energized. 
     The electromagnetic relay  1  has a so-called plunger structure suitably applied to a power transmission path between a battery and a drive circuit for an electric motor in an electric vehicle. That is, in the electromagnetic relay  1 , the movable portion  6  linearly moves relative to the fixed portion  5  along the coil axis direction in accordance with the energization state of the coil  4 , thereby switching the electric current to allow the electric current to flow or not. The coil axial direction is a direction parallel to the coil axis LA which is the central axis of the coil  4 . 
     In  FIG. 1 , the Y-axis direction is taken as the coil axis direction in the XYZ three-dimensional coordinate system of the right hand base. Also, a direction parallel to the X-axis is referred to as a “width direction”, and a direction parallel to the Z-axis is referred to as a “height direction”. A positive direction in the Y-axis will be referred to as “return direction” and a negative direction in the Y-axis will be referred to as “suction direction”. That is, the “coil axis direction” refers to a direction parallel to the Y-axis, and is used not to specify the return direction or the suction direction. 
     The housing  2  is a bathtub-shaped member having an opening at one side in the height direction, and is integrally formed of an insulating material such as a synthetic resin. The frame  3  has a plate-like portion (not shown) formed to close the opening of the housing  2 , and a protruding portion that protrudes in the height direction from the plate-like portion. In  FIG. 1 , a part of the protruding portion of the frame  3  is shown. A shaft insertion hole  31  which is a through hole is formed in the illustrated protruding portion along the coil axis direction. 
     The coil  4 , the fixed portion  5 , and the movable portion  6  are supported by the frame  3 . That is, the coil  4 , the fixed portion  5 , and the movable portion  6  are housed inside the housing space HS. The housing space HS is a space surrounded by the housing  2  and the plate-like portion of the frame  3 . 
     The coil  4  is disposed at one end portion (that is, an end portion in the suction direction) of the housing space HS. The coil  4  is configured to relatively move the movable portion  6  in the suction direction with respect to the fixed portion  5  by generating a magnetic field by energization. 
     The fixed portion  5  is fixed to the frame  3 . A fixed core  51  of the fixed portion  5  is a cylindrical fixed magnetic path forming member made of a ferromagnetic metal material, and is housed inside the coil  4 . That is, the fixed core  51  is arranged coaxially with the coil  4 . A guide hole  52  is formed in the fixed core  51 . The guide hole  52  penetrates the fixed core  51  in the coil axis direction and is provided on the coil axis LA overlapping with the axial center of the fixed core  51 . 
     The movable portion  6  is configured to move in the suction direction by the magnetic field when the coil  4  is energized and to move in the return direction when the coil  4  is de-energized. That is, the movable portion  6  is supported by the frame  3  and the fixed portion  5  so as to reciprocate along the coil axis direction. 
     A movable core  61  of the movable portion  6  is a substantially disk-shaped member made of a ferromagnetic metal material, and is disposed opposite to the fixed core  51  in the return direction with respect to the fixed core  51 . That is, the movable core  61  is provided to move in the suction direction by being attracted to the fixed core  51  by the magnetic field when the coil  4  is energized. The movable core  61  is fixed at an intermediate portion of the movable shaft  62  in the longitudinal direction. 
     The movable shaft  62  is a bar-like member having a longitudinal direction parallel to the coil axis LA and is housed in the guide hole  52  of the fixed core  51  so as to be reciprocally movable along the coil axis direction. An end portion of the movable shaft  62  in the return direction is covered with a movable insulator  63  made of an insulating material such as a synthetic resin. The movable insulator  63  and an end portion of the movable shaft  62  covered with the movable insulator  63  are capable of reciprocating along the coil axis direction within the shaft insertion hole  31 . 
     A return spring  64  is disposed to surround the fixed core  51  in the suction direction of the movable core  61 . The return spring  64 , which is a compression coil spring, is provided so as to bias the movable core  61  in the return direction away from the fixed core  51 . 
     (Configuration of Contact Point Device) 
     The electromagnetic relay  1  includes a contact point device  70 . As is apparent from the description below, the contact point device  70  is provided across the fixed portion  5  and the movable portion  6 . Hereinafter, with reference to  FIGS. 1 to 4 , the configuration of the contact point device  70  of the present embodiment will be described in detail. 
     The contact point device  70  includes a first contactor  71 , a second contactor  72 , an oscillation supporting portion  73 , a contact pressure spring  74 , and a contact cover  75 . In the present embodiment, the contact point device  70  is configured to switch the electric current to flow or not between the first contactor  71  and the second contactor  72  by a relative movement between the first contactor  71  provided at the fixed portion  5  and the second contactor  72  provided at the movable portion  6 . 
     The first contactor  71  is a conductive contact member formed of a conductive metal, and has an outer side surface  711  shaped in a column surrounding a central axis RA along the coil axis direction. In the present embodiment, the first contactor  71  is formed in a cylindrical shape having an axial direction substantially parallel to the coil axis LA. A distal end portion  712  of the first contactor  71  in the return direction is arranged to face the second contactor  72  in the coil axis direction. 
     A flange portion  714  is formed in the intermediate portion  713  of the first contactor  71  in the longitudinal direction. The flange portion  714  protrudes outward from the outer side surface  711  (that is, in a direction away from the central axis RA). The flange portion  714  is covered with the oscillation supporting portion  73 . The oscillation supporting portion  73  includes an insulating elastic member provided in close contact with the outer side surface  711  of the first contactor  71 , and is integrally formed of synthetic rubber or the like. The oscillation supporting portion  73  is fixed to the first contactor  71  such that the flange portion  714  restrains the relative movement of the oscillation supporting portion  73  along the central axis RA with respect to the first contactor  71 . 
     The first contactor  71  is attached to the protruding portion of the frame  3  through the oscillation supporting portion  73 . That is, the first contactor  71  is supported by the oscillation supporting portion  73  to allow the central axis RA to oscillate. 
     Further, in the present embodiment, the pair of first contactors  71  are arranged in the width direction. One and the other of the pair of first contactors  71  are arranged substantially symmetrically with respect to the coil axis LA. The first contactors  71  are electrically insulated from each other by the frame  3  and the oscillation supporting portion  73  in a state of being separated from the second contactor  72  in the coil axis direction. In the case where the electromagnetic relay  1  is mounted on an electric vehicle in the above application, one of the first contactors  71  is electrically connected to a drive circuit for an electric motor and the other is electrically connected to the battery. 
     The second contactor  72  is a conductive contact member made of conductive metal and is formed in a substantially flat plate shape having a thickness direction parallel to the coil axis direction. The second contactor  72  is opposed to the first contactor  71  in the coil axis direction so as to be in electrical contact with the first contactor  71  by being in contact with the first contactor  71 . Further, the second contactor  72  is provided to be reciprocally movable along the coil axis direction while being guided by the frame  3 . In the present embodiment, the second contactor  72  is arranged across the pair of first contactors  71  in the width direction to be in contact with the pair of first contactors  71  to electrically connect the pair of first contactors  71  with each other. 
     An opposing surface  721 , which is one of a pair of main surfaces of the second contactor  72 , is provided to face the pair of first contactors  71 . A back surface  722 , which is the other main surface of the second contactor  72 , is provided to be in contact with the contact pressure spring  74 . 
     The contact pressure spring  74  is a compression coil spring and is disposed between the second contactor  72  and the contact cover  75  so as to bias the second contactor  72  toward the pair of first contactors  71  in the suction direction. The contact cover  75  is made of an insulating material such as a synthetic resin and is formed in a substantially U-shape so as to cover the pair of first contactors  71  and the second contactor  72 . Both ends of the substantially U-shaped contact cover  75  are fixed to the frame  3 . 
     The contact point device  70  has a first contact portion  761  and a second contact portion  762 . In the present embodiment, the first contact portion  761  is provided on the second contactor  72 , and the second contact portion  762  is provided on the first contactor  71 . 
     The first contact portion  761  is formed in a protruding shape protruding from the opposing surface  721  of the plate-shaped second contactor  72  toward the first contactor  71 . Specifically, in the present embodiment, the outer surface of the first contact portion  761  facing the second contact portion  762  has a cylindrical side surface, a top surface shaped in substantially circular, and a curved surface provided between the side surface and the top surface, such as partial spherical surface shape or conical surface shape. 
     In the present embodiment, plural first contact portions  761  are provided so as to face the respective first contactors  71 . That is, a first group of the first contact portions  761  corresponding to one of the pair of first contactors  71  is arranged on one end in the width direction of the second contactor  72 . A second group of the first contact portions  761  corresponding to the other of the pair of first contactors  71  is arranged on the other end in the width direction of the second contactor  72 . 
       FIG. 4  is an enlarged view showing a group of first contact portions  761  provided corresponding to one of the pair of first contactors  71 . As shown in  FIG. 4 , the group of first contact portions  761  are arranged at equal intervals on the circumference CF surrounding the central axis RA. More specifically, the group of first contact portions  761  are arranged such that, in the plan view, the center points are located at equal intervals in the circumferential direction on the circumference CF. Further, in the present embodiment, three first contact portions  761  are provided on one circumference CF. The circumference CF is a curve on the opposing surface  721  substantially perpendicular to the central axis RA, and corresponds to a circle formed around the intersection of the central axis RA and the opposing surface  721 . 
     The second contact portion  762  is provided at the distal end portion  712  of each of the pair of first contactors  71 . As shown in  FIGS. 2 to 4 , the second contact portion  762  protrudes in the coil axis direction toward the virtual space VS surrounded by the plural first contact portions  761 . 
     The second contact portion  762  has a contact surface  763 . The contact surface  763  is a convex curved surface that is exposed toward the virtual space VS and is formed to surround the central axis RA. Specifically, in the present embodiment, the entire contact surface  763  is formed in a partially spherical shape. 
     (Operation and Effect of Embodiment) 
     Hereinafter, the operation and effect achieved by the present embodiment will be described with reference to  FIGS. 1 to 4 . 
     When the energization of the coil  4  is interrupted, the movable core  61  is separated from the fixed core  51  by the urging force of the return spring  64  in the return direction. As a result, the movable shaft  62  integrated with the movable core  61  moves in the return direction. 
     When the movable shaft  62  moves in the return direction, the movable insulator  63  fixed to the tip end of the movable shaft  62  abuts against the second contactor  72  at a position between the first contact portions  761 . Then, when the movable shaft  62  further moves in the return direction, the second contactor  72  moves in the return direction against the biasing force of the contact pressure spring  74 . As a result, as shown in  FIG. 1 , the first contact portion  761  and the second contact portion  762  are separated from each other, and the energization therebetween is interrupted. 
     When the energization of the coil  4  is started, the movable core  61  is attracted to the fixed core  51  by the magnetic field generated by the coil  4 . Then, the movable core  61  moves in the suction direction to a position close to the fixed core  51  against the urging force of the return spring  64 . 
     When the movable core  61  moves in the suction direction, the movable shaft  62  and the movable insulator  63  also move in the suction direction. Then, the second contactor  72  moves in the suction direction to approach the first contactor  71  by the urging force of the contact pressure spring  74  in the suction direction. 
     The second contact portion  762  provided at the distal end portion  712  of the first contactor  71  and the first contact portion  761  provided at the opposing surface  721  of the second contactor  72  abut each other, whereby the first contactor  71  and the second contactor  72  are electrically connected. That is, a current flow path is formed from one of the pair of first contactors  71  via the second contactor  72  to the other of the pair of first contactors  71 . 
     In the present embodiment, the second contact portion  762  provided at the distal end portion  712  of the first contactor  71  advances into the virtual space VS. As a result, the contact surface  763 , which is a curved surface provided on the second contact portion  762  to surround the central axis RA of the first contactor  71 , is in contact with the outer surfaces of the first contact portions  761  facing the virtual space VS. 
     At this time, the first contactor  71  is supported by the oscillation supporting portion  73  to be able to oscillate. Therefore, the contact surface  763 , which is a curved surface exposed toward the virtual space VS on the second contact portion  762  provided at the distal end portion  712  of the first contactor  71 , suitably abuts all of the contact portions  761  facing the virtual space VS. 
     Due to manufacturing errors or the like, there is a possibility that the central axis RA of the first contactor  71  does not pass through the center of the circumference CF on which the group of the first contact portions  761  is disposed when the coil  4  is de-energized. Alternatively, for example, due to manufacturing errors or the like, one of the first contact portions  761  may have the protrusion amount in the coil axis direction or the outer diameter, which is smaller than the others. 
     In this respect, according to the present embodiment, the central axis RA of the first contactor  71  moderately oscillates due to the force applied to the first contactor  71  when the first contact portion  761  and the second contact portion  762  are brought into contact. This oscillation can be a three-dimensional oscillation such as a precession movement, in particular, a conical precession movement. Therefore, even in the above-described case, the second contact portion  762  provided at the distal end portion  712  of the first contactor  71  can abut all of the corresponding group of the first contact portions  761  satisfactorily. 
     As described above, according to the present embodiment, the second contact portion  762  and the plural first contact portions  761  are in contact in a stable manner in the region where the first contactor  71  and the second contactor  72  come close to and oppose each other. Therefore, the contact resistance between the first contactor  71  and the second contactor  72  is satisfactorily reduced. That is, according to the present embodiment, it is possible to satisfactorily reduce the contact resistance during energization without lowering in the reliability which may be caused by change in the material of the contact member or without increase in the size of the device which may be caused by rise in the contact pressure. 
     In addition, since the first contactor  71  is supported to oscillate, a strict parallelism is not required between the normal line of the opposing surface  721  and the central axis RA. The strictness is also not required in the positional relationship relative to the center of the circumference CF. Therefore, according to the present embodiment, the designing can be made flexible for the electromagnetic relay  1  and the contact point device  70 . 
     (Modifications) 
     The present disclosure is not limited to the specific examples described in the above-described embodiment. That is, it is possible to appropriately change the above-described embodiment. Representative modifications will be described below. In the following description of variation examples, only the features different from those of the embodiments described above will be explained. In addition, in the above-described embodiment and the modifications, the same reference numerals are given to the same or equivalent parts. Therefore, in the description of the following modifications, regarding components having the same reference numerals as the components of the above-described embodiment, the description in the above-described embodiment can be appropriately cited unless there is a technical inconsistency or a specific additional explanation. 
     As described above, the electromagnetic relay  1  and the contact point device  70  according to the present disclosure have the plunger structure, and can satisfactorily cope with an increase in system output in the electric vehicle. However, the electromagnetic relay  1  and the contact point device  70  according to the present disclosure are not limited to be applied to the power transmission path between the motor drive circuit and the battery in the electric vehicle. That is, the electromagnetic relay  1  and the contact point device  70  are not limited to being mounted on a vehicle. Further, the electromagnetic relay  1  is not limited to the plunger type. 
     The present disclosure is not limited to the specific examples described in the above-described embodiment. For example, the configurations of the fixed portion  5  and the movable portion  6  are not limited to the above specific examples. 
     For example, the shapes of the fixed core  51 , the movable core  61 , and the like can be appropriately changed from the shapes shown in  FIG. 1 . Specifically, for example, the movable core  61  can be fixed to an end portion of the movable shaft  62  in the suction direction. In this case, the fixed core  51  has no function of guiding the reciprocating movement of the movable shaft  62 . That is, in this case, the guide hole  52  is not formed in the fixed core  51 . 
     The shape of the first contactor  71  is not limited to the above specific example. That is, for example, the first contactor  71  may be formed in a tubular shape having a through hole along the central axis RA. Further, instead of the flange portion  714 , a groove portion can be formed. Alternatively, for example, a portion of the first contactor  71  other than the distal end portion  712  may be formed into a polygonal prism shape. In this case, the flange portion  714  or the groove portion to replace the flange portion  714  can be omitted by providing the oscillation supporting portion  73  to straddle the polygonal prism portion and the columnar portion. 
     The oscillation manner of the oscillation supporting portion  73  supporting the first contactor  71  is not limited to the above specific example. That is, for example, the oscillation supporting portion  73  may be provided to expose the intermediate portion  713  while the end portion of the first contactor  71  opposite to the distal end portion  712  is covered. Alternatively, the oscillation supporting portion  73  may be provided to cover substantially the entirety (that is, a portion other than the distal end portion  712 ) of the outer side surface  711  of the first contactor  71 . 
     There is also no particular limitation on the shape and structure of the oscillation supporting portion  73 . That is, for example, the outer shape of the oscillation supporting portion  73  may be a substantially cylindrical shape as shown in  FIG. 2 , or may be a polygonal prism shape. Further, the oscillation supporting portion  73  may include a member other than the elastic member. That is, for example, the oscillation supporting portion  73  may include an elastic member covering the outer side surface  711  of the first contactor  71  and a tubular rigid member covering the outer peripheral surface of the elastic member. 
     The entirety of the outer surface of the first contact portion  761  facing the second contact portion  762  may be formed in a partially spherical shape. Alternatively, a portion of the first contact portion  761  which does not contact the second contact portion  762  can be omitted as appropriate. That is, for example, the first contact portion  761  can be formed in a partial columnar shape such as a semicircular column shape. The contact surface  763  of the second contact portion  762  may include a cylindrical side surface that surrounds the central axis RA, a top surface shaped in substantially circular, and a ring-shaped partial spherical surface or a conical curved surface provided to surround the central axis RA, between the cylindrical side surface and the top surface. 
     The first contact portion  761  is not limited to the protrusion protruding from the opposing surface  721  of the second contactor  72  along the coil axis direction. Hereinafter, such modifications will be described. 
     As shown in  FIGS. 5 and 6 , the first contact portion  761  may be a protrusion protruding toward the center of a contact forming hole  771  penetrating the second contactor  72  in the thickness direction. Such protrusions may be formed in a partial columnar shape (for example, a semicircular column shape) having an axial direction parallel to the thickness direction of the second contactor  72 . 
     The first contact portions  761  are arranged at equal intervals on the circumference CF. In this case, the circumference CF corresponds to a circumference forming an inner circumference of a circular hole, assuming that the contact forming hole  771  is shaped such that the first contact portions  761  protrude from the inner peripheral surface of the circular hole. Also in this modification, three first contact portions  761  are provided on one circumference CF. The three first contact portions  761  are formed to surround the central axis RA on the opposing surface  721  or the back surface  722  of the second contactor  72 . 
     In such a configuration, the second contact portion  762  provided at the distal end portion  712  of the first contactor  71  enters the opening formed by the contact forming hole  771 . Then, the contact surface  763 , which is a curved surface exposed toward the contact forming hole  771  at the distal end portion  712  of the first contact piece  71 , contacts all of the plural first contact portions  761  facing the contact forming hole  771 . The same effects as those of the embodiment described above can be achieved with this structure. 
     As described above, the above-mentioned protrusion forming the first contact portion  761  may have a semi-cylindrical shape or may not have a semi-cylindrical shape. In the former case, the central axis of the cylindrical surface of the protrusion is located on the circumference CF. In the latter case, the central axis of the cylindrical surface of the protrusion is not located on the circumference CF. 
     In  FIGS. 5 and 6 , the contact forming hole  771  may not be a through hole. That is, the contact forming hole  771  may be a recessed portion closed on the back surface  722 . Further, the inner side of the circumference CF on the opposing surface  721  may be formed in a concave shape. 
     As shown in  FIGS. 7 to 9 , plural first contact portions  761  may be provided at the distal end portion  712  of the first contactor  71 , while the second contact portion  762  may be provided on the second contactor  72 . The same effects as those of the embodiment described above can be achieved with this structure. 
     In this case, the first contact portion  761  protrudes from the end face  781  of the first contactor  71  adjacent to the distal end portion  712  along the central axis RA. That is, the plural first contact portions  761  are provided to surround the central axis RA on the end face  781  which is a plane perpendicular to the central axis RA. 
     The first contact portion  761  is provided as a columnar protrusion formed by connecting two partial cylindrical surfaces whose respective generatrices are parallel to the central axis RA and protrude in opposite directions. One of the two partial cylindrical surfaces forming the outer side surface of the first contact portion  761  is formed to be continuous with the outer side surface  711  of the intermediate portion  713 . That is, the partial cylindrical surface is provided so as to constitute a part of the cylindrical outer side surface  711  of the first contactor  71 . 
     Also in this modification, three first contact portions  761  are provided at equal intervals on one circumference CF. In this case, as shown in  FIG. 9 , the circumference CF corresponds to the outer shape of the first contactor  71  in a plan view. Further, the second contact portion  762  protrudes in the coil axis direction from the opposing surface  721  of the second contactor  72  toward the virtual space VS surrounded by one pair (ie, three) of the first contact portions  761 . 
     As shown in  FIG. 10 , the first contactor  71  may be provided on the movable portion  6 , whereas the second contactor  72  may be provided on the fixed portion  5 . The same effects as those of the embodiment described above can be achieved with this structure. 
     Specifically, in this modification, the first contactor  71  is attached to a movable plate  791  via the oscillation supporting portion  73 . Like the second contactor  72  in the above embodiment, the movable plate  791  is a conductive contact member made of conductive metal and is formed in a substantially flat plate shape having a thickness direction parallel to the coil axis direction. 
     Also in this modification, one and the other of the pair of first contactors  71  arranged in the width direction are arranged substantially symmetrically with respect to the coil axis LA. Each of the first contactors  71  is electrically connected to the movable plate  791  via a wiring portion (not shown). 
     The second contactor  72  is fixed to the protrusion of the frame  3 . In this modification, a pair of second contactors  72  are provided respectively to the pair of first contactors  71 . When the coil  4  is not energized, the pair of second contactors  72  are electrically insulated from each other by the frame  3 , in a state where the first contactor  71  is separated from the second contactor  72 . 
       FIG. 10  shows an example in which plural first contact portions  761  are provided on the second contactor  72  and a second contact portion  762  is provided on the first contactor  71 , similarly to the above embodiment. That is, in  FIG. 10 , each of the second contactors  72  has plural first contact portions  761 . The detailed structure of the contact point device  70  in  FIG. 10  is the same as that shown in  FIGS. 2 to 4  except that the second contactor  72  is divided into two. 
     In  FIG. 10 , the oscillation supporting portion  73  may be formed of a conductive material. That is, the pair of first contactors  71  may be electrically connected to each other via the oscillation supporting portion  73  and the movable plate  791 . Further, modifications corresponding to  FIGS. 5 and 6  or modifications corresponding to  FIGS. 7 to 9  can be applied to the modification shown in  FIG. 10 . 
     Two first contact portions  761  may be provided on one circumference CF. Alternatively, four or more first contact portions  761  may be provided on one circumference CF. In case where three or more first contact portions  761  are provided on one circumference CF, the first contact portions  761  may be arranged at equal or non-equal intervals on the circumference CF. 
     In the above description, the seamlessly integrally formed member may be configured to have a seam due to adhesion among plural members or the like. Likewise, the plural members separately provided may be joined integrally and seamlessly to each other. There is no particular limitation on the material forming each member. 
     The modifications are not limited to the above description. Plural modifications may be combined with each other. Furthermore, some of the configurations in the above embodiment and some configurations in each of the above modifications can be combined with each other.