Electromagnetic relay

Abstract

Electromagnetic relay, characterized in that it comprises: a first movable contact (86a, 87b) and a second movable contact (86b, 87a) arranged on a movable contact piece (80, 81), a first fixed contact (21a, 24a) and a second fixed contact (22a, 23a) arranged to be contactable and separable from the first movable contact (86a, 87b) and the second movable contact (86b, 87a), respectively; and a magnetic field generating unit (35) arranged to attract an arc generated between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) and an arc generated between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a) in a predetermined direction, in which, when a predetermined period of time has elapsed after the generation of an arc at least either between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) or between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a), an arc generated between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) is elongated by the magnetic field generating unit (35) so that it is longer than an arc generated between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a).

Description

TECHNICAL AREA

[0001] The present invention relates to an electromagnetic relay, particularly to an electromagnetic relay that can efficiently extinguish a generated arc. TECHNICAL BACKGROUND

[0002] As a conventional electromagnetic relay, for example, an electromagnetic relay is known that includes: an armature that pivots upon energization and de-energization of an electromagnetic block; a movable contact portion having a movable contact, mounted on the armature, and pivoting along with the pivoting of the armature; and a fixed contact portion having a fixed contact, with which the movable contact comes into and out of contact. In the electromagnetic relay, an arc expansion space is formed for expanding an arc generated when the movable contact comes into or out of contact with the fixed contact, and a magnetic field generation unit is provided for guiding an arc generated when the movable contact comes into or out of contact with the fixed contact to the arc expansion space (refer to PTL 1).

[0003] In the above electromagnetic relay, as shown in the Fig. 7A and Fig. 7B, a fixed contact 22a is disposed on an upper edge of a base 30, and a movable contact 21a is disposed inside the fixed contact 22a. The electromagnetic relay is configured so that an arc generated between the movable contact 21a and the fixed contact 22a is attracted upward and elongated by the magnetic force of a permanent magnet 50 to thereby be eliminated.

[0004] Further prior art is provided by the documents EP 2 672 497 B1, DE 10 2012 021 397 A1 and CN 1 02 129 935 A.

[0005] EP 2 672 497 B1 describes an electromagnetic relay comprising an armature that oscillates according to the energization and de-energization of an electromagnetic block, movable contact elements provided with movable contact points and attached to the armature to move in conjunction with the moving armature, and fixed contact elements provided with fixed contact points with and from which the movable contact points come into contact and separate. The electromagnetic relay is provided with arc expansion spaces for expanding an arc generated at the contact point and the separation between the movable contact points and the fixed contact points, and a magnetic field generating device is provided for introducing the arc generated at the contact point and the separation between the movable contact points and the fixed contact points into the arc expansion spaces.

[0006] DE 10 2012 021 397 A1 describes an electromagnetic contactor with a contact device comprising: a pair of fixed contact pieces arranged with a predetermined gap therebetween; a movable contact piece arranged such that it can be freely brought into contact with and separated from the pair of fixed contact pieces; and a contact housing made of an insulating material for accommodating the movable and fixed contact pieces. The contact device further comprises a pair of inner arc-extinguishing permanent magnets and a pair of outer arc-extinguishing permanent magnets. The inner arc-extinguishing permanent magnets are arranged on the inside of the contact housing, parallel to the longitudinal direction of the movable contact piece, close to the movable contact piece. The inner arc-extinguishing permanent magnets are magnetized such that their opposing magnetic pole faces are of the same magnetic pole type.The outer arc-extinguishing permanent magnets are arranged on the outer sides of the contact housing at a location opposite the inner arc-extinguishing permanent magnets. The outer arc-extinguishing permanent magnets are magnetized so that their magnetization direction is the same as that of the nearby inner arc-extinguishing permanent magnet, and the coercive force of the outer arc-extinguishing permanent magnets is greater than that of the inner arc-extinguishing permanent magnets.

[0007] CN 1 02 129 935 A describes an arc extinguishing system for a non-polar DC contactor. LIST OF CITED DOCUMENTS PATENT LITERATURE

[0008] PTL 1: Unexamined Japanese patent application JP 2013 -080692 A SUMMARY OF THE INVENTION TECHNICAL PROBLEM

[0009] However, in the above electromagnetic relay, the permanent magnet is arranged between adjacent fixed contacts to extend the arc upward. Since the electromagnetic relay requires an arc-extinguishing space of an equivalent size for each pair of movable contact 21a and fixed contact 22a, the device can hardly be reduced in size and has limited design flexibility, which has proven problematic.

[0010] In view of the above problem, it is an object of the present invention to provide an electromagnetic relay whose size can be easily reduced and which offers great design flexibility. This object is achieved by the subject matter of the independent claims. Further advantageous developments and embodiments of the invention emerge from the dependent claims. SOLUTION TO THE PROBLEM

[0011] An electromagnetic relay according to the present invention comprises: a first movable contact and a second movable contact arranged on a movable contact piece, a first fixed contact and a second fixed contact arranged to be contactable and separable from the first movable contact and the second movable contact, respectively; and a magnetic field generating unit arranged to attract an arc generated between the first movable contact and the first fixed contact and an arc generated between the second movable contact and the second fixed contact in a predetermined direction, in which, when a predetermined period of time after the generation of an arc at least between the first movable contact and the first fixed contact or between the second movable contact and the second fixed contact, an arc generated between the first movable contact and the first fixed contact is elongated by the magnetic field generating unit so that it is longer than an arc generated between the second movable contact and the second fixed contact. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0012] According to the present invention, when a predetermined period of time has elapsed after an arc is generated at least between either the first movable contact and the first fixed contact or between the second movable contact and the second fixed contact, the arc generated between the first movable contact and the first fixed contact is cut off by being elongated by the magnetic field generating unit to be longer than the arc generated between the second movable contact and the second fixed contact. Therefore, there is no need to provide an arc extinguishing space of an equivalent size for each pair of movable contact and fixed contact.

[0013] For example, the arc generated between the first movable contact and the first fixed contact can be cut off by being elongated by the magnetic field generation unit and attracted to the arc-extinguishing space, which is a dead space within the electromagnetic relay. Therefore, the arc-extinguishing space for extinguishing the arc generated between the second movable contact and the second fixed contact does not need to have a size equivalent to that of the dead space. As a result, it is possible to obtain an electromagnetic relay whose size can not only be easily reduced but also offers great design flexibility.

[0014] Another electromagnetic relay according to the present invention may comprise: a first movable contact and a second movable contact arranged on a movable contact piece, a first fixed contact and a second fixed contact arranged to be contactable and separable from the first movable contact and the second movable contact, respectively; and a magnetic field generating unit arranged to attract an arc generated between the first movable contact and the first fixed contact and an arc generated between the second movable contact and the second fixed contact in a predetermined direction, wherein the magnetic flux density of the magnetic field generating unit is adjusted such that the magnetic flux density between the first movable contact and the first fixed contact is greater than the magnetic flux density between the second movable contact and the second fixed contact.

[0015] According to the present invention, when a predetermined period of time has elapsed after the generation of an arc between the first movable contact and the first fixed contact, the arc generated between the first movable contact and the first fixed contact is cut off by being elongated by the magnetic field generating unit to be longer than the arc generated between the second movable contact and the second fixed contact. Therefore, the arc extinguishing space for extinguishing the arc generated between the second movable contact and the second fixed contact can be small. Therefore, even if a plastic mold is arranged near the second movable contact and the second fixed contact, the arc hardly comes into contact with the mold, and it is reliably possible to prevent the generation of dust and organic gas.

[0016] Another electromagnetic relay according to the present invention may comprise: a first movable contact and a second movable contact arranged on a movable contact piece, a first fixed contact and a second fixed contact arranged to be contactable and separable from the first movable contact and the second movable contact, respectively; and a magnetic field generating unit arranged to attract an arc generated between the first movable contact and the first fixed contact and an arc generated between the second movable contact and the second fixed contact in a predetermined direction, wherein the contact-to-contact distance between the first movable contact and the first fixed contact at the time of contact separation is made larger than the contact-to-contact distance between the second movable contact and the second fixed contact at the time of contact separation.

[0017] According to the present invention, the first movable contact and the first fixed contact are separated from each other earlier than the second movable contact and the second fixed contact.

[0018] That is, the arc between the first movable contact and the first fixed contact is generated earlier than the arc between the second movable contact and the second fixed contact. For this reason, by adjusting the distance between the contacts at the time of their separation, the arc generated between the first movable contact and the first fixed contact is elongated and interrupted earlier than the arc generated between the second movable contact and the second fixed contact. As a result, the arc extinguishing space for extinguishing the arc generated between the second movable contact and the second fixed contact can be small. Accordingly, even if a plastic mold is arranged near the second movable contact and the second fixed contact, the arc hardly comes into contact with the mold, and it is reliably possible to prevent the generation of dust and organic gas.

[0019] As an embodiment of the present invention, the shape of the movable contact piece may be selected such that the distance from the movable contact piece to the first fixed contact is greater than the distance from the movable contact piece to the second fixed contact.

[0020] According to the present embodiment, the distance between the contacts is adjusted by the shape of the movable contact piece to enable adjustment of the time of arc generation.

[0021] As another embodiment of the present invention, the height dimension of the first fixed contact may be made smaller than the height dimension of the second fixed contact.

[0022] According to the present embodiment, the distance between the contacts is adjusted by using fixed contacts with different height dimensions to enable adjustment of the time of generation of the arc.

[0023] As a novel embodiment of the present invention, the height dimension of the first movable contact can be made smaller than the height dimension of the second movable contact.

[0024] According to the present embodiment, the distance between the contacts is adjusted by using movable contacts with different height dimensions to enable adjustment of the time of generation of the arc.

[0025] As another embodiment of the present invention, the arc generated between the first movable contact and the first fixed contact may be attracted and extended toward an arc extinguishing space arranged in a direction opposite to the opposing first fixed contact or the opposing first movable contact, respectively, as viewed from the first movable contact or the first fixed contact.

[0026] According to the present embodiment, the arc can be extended to a sufficient length by attracting the arc toward the arc extinguishing space, thereby achieving the effect of reliably cutting off or interrupting the arc. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A and Fig. 1B are overall perspective views of an electromagnetic relay according to the present invention, viewed obliquely from above and obliquely from below, respectively. Fig. 2A and Fig. 2B are overall perspective views of the electromagnetic relay according to the present invention with a cover removed therefrom, viewed obliquely from above and obliquely from below, respectively. Fig. 3 is an exploded perspective view of the Fig. 1A and Fig. 1B shown electromagnetic relay, seen diagonally from above. Fig. 4 is an exploded perspective view of the Fig. 1A and Fig. 1B shown electromagnetic relay, seen diagonally from below. Fig. 5A and Fig. 5B are lateral sectional views obtained by cutting the electromagnetic relay at different positions. Fig. 6A and Fig. 6B are horizontal sectional views obtained by cutting the electromagnetic relay at different positions. Fig. 7A and Fig. 7B are longitudinal sectional views obtained by cutting the electromagnetic relay at different positions. Fig. 8A and Fig. 8B are a longitudinal sectional view and a partially enlarged longitudinal sectional view of the electromagnetic relay, respectively. Fig. 9A and Fig. 9B are longitudinal sectional views obtained by cutting the electromagnetic relay after actuation at different positions. Fig. 10A and Fig. 10B are a top view and a bottom view of a base. Fig. 11A and Fig. 11B are a perspective view and a right view showing a modified example of an auxiliary yoke, and Fig. 11C and Fig. 11D are a perspective view and a right view, respectively, showing another modified example of the auxiliary yoke. Fig. 12A and Fig. 12B are a perspective view and a longitudinal sectional view showing a sheet cutting member, respectively, and Fig. 12C and Fig. 12D are a perspective view and a longitudinal sectional view showing another modified example of the sheet cutting member, respectively. Fig. 13A and Fig. 13B are a schematic plan view and a schematic front view showing a contact mechanism, respectively. Fig. 14A and Fig. 14B are a plan view and a front view showing, with vector lines, magnetic force lines of permanent magnets of an electromagnetic relay according to a working example 1. Fig. 15A and Fig. 15B are a plan view and a front view showing, with intensity representation, magnetic flux densities of the permanent magnets of the electromagnetic relay according to Working Example 1. Fig. 16A and Fig. 16B are a plan view and a front view showing, with vector lines, magnetic force lines of permanent magnets of an electromagnetic relay according to a working example 2. Fig. 17A and Fig. 17B are a plan view and a front view showing, with intensity representation, magnetic flux densities of the permanent magnets of the electromagnetic relay according to Working Example 2. Fig. 18 is a front sectional view of an electromagnetic relay according to a second embodiment. Fig. 19 is a sectional view of the Fig. 18 electromagnetic relays shown from above. Fig. 20 is a sectional view of the Fig. 18 electromagnetic relays shown from the left. Fig. 21 is a top sectional view according to a third embodiment. Fig. 22 is a partially enlarged view of the Fig. 21 shown sectional view from above. Fig. 23 is a top sectional view according to a fourth embodiment. Fig. 24 is a partially enlarged view of the Fig. 23 shown sectional view from above. Fig. 25 is a top sectional view according to a fifth embodiment. Fig. 26 is a partially enlarged view of the Fig. 25 shown sectional view from above. Fig. 27 is a graph according to a working example 3 of the present invention. Fig. 28 is a graph according to a working example 4 of the present invention. Fig. 29 is a graph according to Comparative Example 1. Fig. 30 is a left sectional view of the electromagnetic relay according to the second embodiment. Fig. 31 is a graph according to a working example 5. DESCRIPTION OF EMBODIMENTS

[0027] An electromagnetic relay according to the present invention will be described with reference to the accompanying drawings of Fig. 1A to 31.

[0028] An electromagnetic relay according to the first embodiment ( Fig. 1A to 2B) is roughly constructed from a base 10, fixed contact terminals 21 to 24, a magnetic field generating unit 35, an electromagnetic block 40, a movable iron piece 60, movable contact pieces 80, 81 and a cover 90, as shown in the Fig. 3 and Fig. 4 shown.

[0029] As in Fig. 10A, a pair of partition walls 12, 12 having an L-shaped cross section are provided in the base 10 so as to protrude on the left and right sides, respectively, of a recessed portion 11 provided in the center of the upper surface. Further, in the base 10, one edge of the edges vertically opposite to each other with the recessed portion 11 therebetween is provided with a step portion 13, and the other edge is provided with a press-fit hole 14. The step portion 13 serves to hold a coil bobbin 41, described later, of the electromagnetic block 40. The press-fit hole 14 is for press-fitting the lower end 57a of a yoke 55 of the electromagnetic block 40. In the base 10, terminal holes 15a to 15d are provided on the same straight line along one edge of the opposite edges on the upper surface, and terminal holes 16, 16 are provided along the other edge.In addition, arc extinguishing spaces 19, 19 are formed in the base 10, respectively, between the partition walls 12, 12 and the terminal holes 15a, 15d. Furthermore, a pair of engaging claw portions 10a are formed in the base 10 on each of the outer side surfaces, which are opposed to each other, with the partition walls 12, 12 interposed therebetween.

[0030] According to the present embodiment, there is an advantage that an increase in the size of the electromagnetic relay can be effectively avoided by using the dead space of the base 10 as the arc extinguishing space 19.

[0031] In the lower surface of the base 10, as shown in Fig. 10B, substantially L-shaped notched grooves 17, 17, which are recessed portions, are provided behind the terminal holes 15a, 15d, respectively, where the fixed contact terminals 21, 24 are to be inserted (in the direction opposite to a direction in which the later-described movable contacts 86a, 87b are installed, as viewed from the terminal holes 15a, 15d). A part of the notched groove 17 communicates with the outside outside the side surface of the base 10 and can accommodate a first permanent magnet 30 and an auxiliary yoke 31, which will be described later. Furthermore, a recessed portion 18 for accommodating a later-described second permanent magnet 32 ​​is provided in the base 10 between the terminal holes 15b, 15c.In addition, a pair of ribs 10b, 10b are provided in the base 10 so as to protrude from the lower surface so as to prevent the electromagnetic relay according to the present invention from being tilted when it is mounted on a substrate.

[0032] As in the Fig. 13A and Fig. 13B, the fixed contact terminals 21 to 24 ( Fig. 3 and Fig. 4) have the fixed contacts 21a to 24a fixed at their upper ends, and terminal portions 21b to 24b at their lower ends. The terminal portions 21b to 24b are then inserted into the terminal holes 15a to 15d ( Fig. 10A and Fig. 10B) of the base 10, and the fixed contacts 21a to 24a are thereby aligned on the same line. The four fixed contacts 21a to 24a are arranged in this manner for the purpose of reducing a load voltage to be applied to each of the four fixed contacts 21a to 24a. Therefore, it is possible to prevent the generation of an arc at the time of opening or closing a DC power supply circuit.

[0033] As in the Fig. 3 and Fig. 4, each coil terminal 25 has a bent connecting portion 25a at its upper end portion and a connecting portion 25b at its lower end portion. The connecting portions 25b are then inserted into the respective connecting holes 16 ( Fig. 10A and Fig. 10B) of the base 10, and the connecting sections 25, 25 are thereby aligned on the same straight line.

[0034] As in the Fig. 3, Fig. 4, Fig. 13A and Fig. 13B, the magnetic field generating unit 35 is constructed of the first permanent magnet 30, the auxiliary yoke 31, and the second permanent magnet 32. In addition, the first permanent magnet 30 is arranged in a direction in which the fixed contacts 21a, 24a and the movable contacts 86a, 87b come into and out of contact with each other, namely, in the direction opposite to the movable contacts 86a, 87b from the fixed contacts 21a, 24a ( Fig. 6B). In addition, the auxiliary yoke 31 is arranged so that it is adjacent to the first permanent magnet 30. The second permanent magnet 32 ​​( Fig. 7B) is also connected between the fixed contact 22a and the fixed contact 23a as shown in Fig. 6B.

[0035] The directions of the magnetic poles of the first permanent magnet 30 and the second permanent magnet 32 ​​are set according to a direction of a current flowing between the fixed contacts 21a to 24a and the movable contacts 86a, 86b, 87a, and 87b when the fixed contact terminals 22, 23 are electrically connected. Therefore, the first permanent magnet 30, the auxiliary yoke 31, and the second permanent magnet 32 ​​can respectively attract arcs generated between the fixed contacts 21a, 22a, 23a, and 24a and the movable contacts 86a, 86b, 87a, and 87b in predetermined directions to extend and extinguish the arcs.

[0036] Specifically, by adjusting the shape or position of the auxiliary yoke 31, the magnetic lines of force of the first permanent magnet 30 can be changed in desired directions. Therefore, it is possible to prevent the leakage of a magnetic flux of the first permanent magnet 30 in the first permanent magnet 30 while adjusting the arc attraction direction, thereby improving the magnetic efficiency.

[0037] That is, as in Fig. 6A and Fig. 6B, the first permanent magnet 30 and the auxiliary yoke 31 are arranged to generate lines of magnetic force capable of attracting the arc generated between the fixed contact 21a and the movable contact 86a in the direction away from the movable contact 86a as viewed from the fixed contact 21a.

[0038] In addition, the first permanent magnet 30 and the auxiliary yoke 31 are arranged to generate lines of magnetic force capable of attracting the arc generated between the fixed contact 24a and the movable contact 87b in the direction away from the movable contact 87b as viewed from the fixed contact 24a.

[0039] The second permanent magnet 32 ​​is arranged to generate lines of magnetic force capable of attracting the arc generated between the fixed contact 22a and the movable contact 86b to move toward the top of the base 10.

[0040] In addition, the second permanent magnet 32 ​​is arranged to generate lines of magnetic force capable of attracting the arc generated between the fixed contact 23a and the movable contact 87a in the direction opposite to the top of the base 10.

[0041] It should be noted that the electromagnetic relay according to the present embodiment has four poles. However, in the present embodiment, the arc generated between the fixed contact 22a and the opposing movable contact 86b and the arc generated between the fixed contact 23a and the opposing movable contact 87a can be attracted by three permanent magnets in predetermined directions. Thus, there is an advantage in that the number of components is smaller than in the conventional case.

[0042] In the present embodiment, the description has been given of the configuration in which, as shown in Fig. 6B, the generated arc is attracted to move obliquely upward in the direction away from the movable contact 86a and the movable contact 87b, as viewed from the fixed contacts 21a and 24a, respectively. However, this is not limitative, and the positions of the fixed contact 21a and the movable contact 86a or the positions of the fixed contact 24a and the movable contact 87b may be interchanged. By interchanging the positions in this way, the directions of the magnetic poles of the first permanent magnet 30 and the second permanent magnet 32 ​​can be appropriately adjusted according to the direction of a current flowing between the fixed contacts 21a, 22a, 23a, and 24a and the movable contacts 86a, 86b, 87a, and 87b, respectively, when the fixed contact terminals 22, 23 are electrically connected.Therefore, it is possible to attract the generated arc to move obliquely upward in the direction away from the fixed contacts 22a, 23a, as seen from the movable contact 86a and the movable contact 87b.

[0043] The first permanent magnet 30 and the additional yoke 31 are inserted into the notched groove 17 ( Fig. 10A and Fig. 10B). The auxiliary yoke 31 is thereby positioned so that it is adjacent to the first permanent magnet 30. The second permanent magnet 32 ​​is received in the recessed portion 18 provided in the base 10.

[0044] According to the present embodiment, the first and second permanent magnets 30, 32 and the auxiliary yoke 31 are mounted from the bottom of the base 10. Therefore, it is possible to prevent damage to the first and second permanent magnets 30, 32 and the auxiliary yoke 31 caused by the generated arc. In addition, since the thickness of the base 10 can be efficiently utilized, it is possible to obtain a space-saving electromagnetic relay.

[0045] It should be noted that each of the first permanent magnet 30 and the auxiliary yoke 31 and the second permanent magnet 32 ​​need not necessarily be mounted from the bottom side of the base 10, but they can also be mounted from the top side of the base 10 as required.

[0046] In addition, the permanent magnet, or the permanent magnet and the additional yoke, can each be arranged behind the fixed contacts 21a to 24a.

[0047] The protruding auxiliary yoke 31 is not limited to the rectangular-shaped flat magnetic element, but may, for example, have a substantially L-shape ( Fig. 11A and Fig. 11B). According to this modified example, the directions of the lines of magnetic force of the first permanent magnet 30 can be changed to directions different from those in the case of using the rectangular flat magnetic member. Therefore, the arc attraction direction can be changed to a desired direction by appropriately adjusting the shape and position of the auxiliary yoke 31.

[0048] In addition, the protruding auxiliary yoke 31 may be a rectangular flat magnetic element with beveled corners ( Fig. 11C and Fig. 11D). With the chamfered corners, this modified example has the advantage of being easier to insert into the notched groove 17 and can improve the ease of assembly.

[0049] In the arc extinguishing chamber 19, for example, a Fig. 12A and Fig. 12B. This serves to quickly cool the generated arc and efficiently extinguish or extinguish the arc.

[0050] The sheet cutting member 100 is formed by bending a metal plate strip into a substantially J-shape in cross section. A plurality of protrusions 101, which are substantially triangular in cross section, are provided to protrude from the front of the sheet cutting member 100. The protrusions 101 serve to increase the contact area with the sheet to improve the rapid cooling efficiency. On both side edges of the front of the sheet cutting member 100, ribs 102 are bent and raised to face each other. Furthermore, on both side edges of the bottom of the sheet cutting member 100, ribs 103 are bent and raised to face each other. The ribs 102, 103 serve to prevent the generated sheet from leaking from the arc extinguishing space 19.

[0051] As a further sheet cutting element 100, for example as shown in Fig. 12C and Fig. 12D, a plurality of tongue members 104 may be cut out and raised from the front side. Since the other components are the same as those of the above-mentioned sheet cutting member 100, the same portions are designated by the same reference numerals, and their descriptions will be omitted. Note that the sheet cutting member can be easily made of metal and is not limited to the metal plate.

[0052] As in the Fig. 3 and Fig. 4, the electromagnetic block 40 is formed of a coil body 41, a coil 51, an iron core 52 and a yoke 55.

[0053] In the coil body 41, a through hole 45 of rectangular cross section is provided in a body portion 44 having flange portions 42, 43 at both ends, and an insulating rib 46 is provided so as to protrude laterally from the outer surface of one flange portion 42. Furthermore, removal of the coil body 41 is prevented by engaging relay claws 50 with engaging holes 47 provided on both side edges of the other flange portion 43 ( Fig. 7B).

[0054] As in Fig. 3, the coil 51 is wound around the body portion 44, and a lead wire of the coil 51 is connected to a connecting portion 50a ( Fig. 6A) extending from the relay claw 50.

[0055] As in Fig. As shown in Figure 3, the iron core 52 is formed by stacking a plurality of flat magnetic elements having a substantially T-shape in plan view. The iron core 52 is then passed through the through-hole 45 of the coil bobbin 41. One protruding end of the iron core 52 is used as a magnetic pole portion 53, and the other protruding end 54 is crimped and fixed to a vertical portion 57 of the yoke 55 having a substantially L-shape in cross section, which will be described later.

[0056] The yoke 55 is made of a magnetic plate bent to have a substantially L-shape in cross section. In the yoke 55, an engaging protrusion 56a is bent and raised at the center of a horizontal portion 56, and retaining protrusions 56b are cut and raised at both side edges of the tip of the horizontal portion 56. Furthermore, the yoke 55 is designed in such a shape that the lower end 57a of the vertical portion 57 can be press-fitted into the press-fit hole 14 of the base 10.

[0057] The movable iron piece 60 is made of a flat magnetic element. As shown in Fig. 3 and Fig. 4, an engaging projection 61 is provided in the movable iron piece 60 so as to extend from the upper edge, and notch portions 62, 62 are provided on both side edges.

[0058] In the movable iron piece 60, the notched portion 62 is engaged with the holding projections 56b of the yoke 55. In addition, the movable iron piece 60 is rotatably supported by coupling the engaging projection 61 with the engaging projection 56a of the yoke 55 via a return spring 63.

[0059] The movable contact pieces 80, 81 each have a substantially T-shape in front view, and the movable contacts 86a, 86b, 87a, 87b are connected at both ends of large-width portions 82, 83 of the movable contact pieces 80, 81 via conductive coating members 84, 85. The coating members 84, 85 substantially increase the cross-sectional areas of the large-width portions 82, 83 to reduce electrical resistance and suppress heat generation. Furthermore, as described above, the arc is attracted to move obliquely upward in the direction away from the movable contact 86a and the movable contact 87b, as viewed from the fixed contacts 21a, 24a. As a result, the generated arc hardly comes into contact with the movable contact pieces 80, 81 themselves, and it is therefore possible to prevent damage to the movable contact pieces 80, 81 caused by the arc.

[0060] The movable contact pieces 80, 81 are formed integrally with a movable platform 74 by injection molding their upper ends. In addition, as shown in Fig. 7B, the movable stage 74 is fixedly connected to a spacer 70 and the movable iron piece 60 via a rivet 64. As shown in Fig. 4, the spacer 70 improves the insulation properties of the movable iron piece 60 by pressing the movable iron piece 60 into a recessed portion 71 provided on the inside of the spacer 70. An insulation rib 72 ( Fig. 3 and Fig. 7B) is provided at the lower side edge of the inner surface, and an insulating rib 73 ( Fig. 3 and Fig. 7B) for separating the movable contact pieces 80, 81 is provided so as to extend laterally from the lower side edge of the outer surface.

[0061] In addition, the electromagnetic block 40 with the mounted movable contact pieces 80, 81 is accommodated in the base 10, and a flange portion 42 of the coil body 41 is mounted on the step portion 13 ( Fig. 7B) of the base 10. Then, the lower end 57a of the yoke 55 is pressed into the press-in hole 14 of the base 10 and positioned. Accordingly, the relay claws 50 of the electromagnetic block 40 engage a terminal portion 25a of the coil terminal 25 ( Fig. 7A). In addition, the movable contacts 86a, 86b, 87a, 87b are contactable and separable from the fixed contacts 21a, 22a, 23a, and 24a, respectively. As in Fig. 8B, the insulating rib 72 of the spacer 70 is arranged at the top near the insulating rib 46 of the coil body 41.

[0062] More specifically, at least one of the insulating ribs 46 and 72 is arranged to interrupt the shortest line between the individual fixed contacts 22a, 23a (or the fixed contact terminals 22, 23) and the magnetic pole portion 53. This results in an increase in the spatial distance from the magnetic pole portion 53 of the iron core 52 to the individual fixed contacts 22a, 23a, and therefore, good insulation properties can be achieved.

[0063] Furthermore, the insulating rib 72 may be arranged to interrupt the shortest line between the edge at the tip of the insulating rib 46 and the magnetic pole portion 53. This may result in an increase in the spatial distance from the magnetic pole portion 53 of the iron core 52 to the individual fixed contacts 22a, 23a, and therefore, better insulation properties can be achieved.

[0064] It should be noted that a length dimension of the insulating rib 46 protruding from the outer surface of the flange portion 42 is preferably a length dimension smaller than the distance from the outer surface of the flange portion 42 to the tip of each of the fixed contacts 22a, 23a. This is because if the length dimension of the insulating rib 46 is a length dimension greater than the distance from the outer surface of the flange portion 42 to the tip of each of the fixed contacts 22a, 23a, operation of the movable contact pieces 80, 81 may be hindered. Another reason is that arcs generated between each of the fixed contacts 22a, 23a and the movable contacts 86b, 87a are more likely to strike the insulating rib 72, resulting in the insulating rib 72 being easily damaged.Accordingly, a further preferred length dimension of the insulating rib 46 is a length dimension from the outer surface of the flange portion 42 to the outer surface of the individual fixed contact terminals 22, 23.

[0065] As in the Fig. 3 and Fig. As shown in Figure 4, the lid 90 has a box shape that can be placed on the base 10 with the electromagnetic block 40 mounted therein. A pair of gas outlet holes 91, 91 are provided on the ceiling surface of the lid 90. Furthermore, engagement receiving holes 92 for engagement with the engagement claw portions 10a of the base 10 are provided on the opposite inner side of the lid 90, and position adjusting ribs 93 ( Fig. 5B) are designed to protrude from the interior surface of the ceiling.

[0066] Therefore, when the cover 90 is placed on the base 10 with the electromagnetic block 40 installed therein, the engagement receiving hole 92 of the cover 90 is engaged with and connected to the engagement claw portion 10a of the base 10. The position adjusting ribs 93 then come into contact with the horizontal portion 56 of the yoke 55 to adjust the lifting of the electromagnetic block 40 ( Fig. 5B). Next, the assembly process is completed by hermetically sealing the base 10 and the lid 90 by injecting and curing a sealing material (not shown in the drawing) onto a lower surface of the base 10.

[0067] In the present embodiment, the sealing material is injected to allow the first and second permanent magnets 30, 32 and the auxiliary yoke 31 to be fixed to the base 10 while sealing a gap between the base 10 and the cover 90. Therefore, according to the present embodiment, it is possible to obtain an electromagnetic relay with high productivity while performing a small number of steps.

[0068] Next, the operation of the above embodiment will be described.

[0069] When the electromagnetic block 40 is not energized, as in the Fig. 7A and Fig. As shown in Fig. 7B, the movable iron piece 60 is urged clockwise by the spring force of the return spring 63. Therefore, the movable contacts 86a, 86b, 87a, 87b are separated from the fixed contacts 21a, 22a, 23a, and 24a, respectively.

[0070] When a voltage is applied to the coil 51 for excitation, the movable iron piece 60 is attracted to the magnetic pole portion 53 of the iron core 52, and the movable iron piece 60 rotates clockwise against the spring force of the return spring 63. For this reason, the movable contact pieces 80, 81 rotate together with the movable iron piece 60, and the movable contacts 86a, 86b, 87a, 87b come into contact with the fixed contacts 21a, 22a, 23a, and 24a, respectively. Thereafter, the movable iron piece 60 is attracted to the magnetic pole portion 53 of the iron core 52 ( Fig. 9A and Fig. 9B).

[0071] Thereafter, when the application of voltage to the coil 51 is stopped, the movable iron piece 60 moves clockwise by the spring force of the return spring 63, and the movable iron piece 60 is separated from the magnetic pole portion 53 of the iron core 52. Thereafter, the movable contacts 86a, 86b, 87a, 87b are separated from the fixed contacts 21a, 22a, 23a, and 24a, respectively, to return to the initial state.

[0072] According to the present embodiment, as shown in the Fig. 6A to 7B, even if an arc 110 is generated at the time of separation of the movable contacts 86a, 87b from the fixed contacts 21a, 24a, the magnetic lines of force of the first permanent magnet 30 act on the arc 110 via the auxiliary yoke 31. Therefore, according to Fleming's left-hand rule, the generated arc 110 is attracted by the Lorentz force toward the arc extinguishing space 19 of the base 10 to be expanded and extinguished.

[0073] According to the present embodiment, the arc 110 can be attracted obliquely to the back of the fixed contacts 21a, 24a and extinguished only by the first permanent magnet 30. Obliquely to the back of the fixed contacts 21a, 24a here means a direction that, as viewed from the fixed contacts 21a, 24a, is opposite to the opposing movable contacts 86a, 87b and in the direction away from the base.

[0074] Furthermore, by disposing the auxiliary yoke 31, the arc 110 can be attracted in a right and left direction to adjust the direction of attraction. The right and left direction of the arc 110 means a direction orthogonal to a direction in which the fixed contacts 21a, 24a and the movable contacts 86a, 87b face each other, and a direction parallel to the upper surface of the base.

[0075] Therefore, according to the present embodiment, the generated arc 110 does not come into contact with the inner surface of the lid 90 and the electromagnetic block 40, and is thereby extended obliquely toward the back in a suitable direction. This makes it possible to extinguish the arc 110 more efficiently. According to the present embodiment, there is an advantage in that an increase in the size of the device can be avoided because the dead space located behind each of the fixed contacts 21a, 24a is efficiently utilized as the arc extinguishing space 19.

[0076] Needless to say, the shapes, sizes, materials, arrangement and the like of the first and second permanent magnets 30, 32 and the auxiliary yoke 31 are not limited to those described above, but can be changed as required. Working example 1

[0077] A working example 1 is an analysis of the directions and strength of the magnetic force lines in the case of combining the first and second permanent magnets 30, 32 with the auxiliary yoke 31.

[0078] As a result of the analysis, the directions of the magnetic lines of force are shown by vector lines ( Fig. 14A and Fig. 14B), and the strength of the magnetic lines of force is shown by the intensity ( Fig. 15A and Fig. 15B). Working example 2

[0079] A working example 2 is an analysis of the directions and strengths of the lines of magnetic force in the case of arranging the components in the same manner as in the above-described working example 1 except that the auxiliary yoke 31 is not provided.

[0080] As a result of the analysis, the directions of the magnetic lines of force are shown by vector lines ( Fig. 16A and Fig. 16B), and the strength of the magnetic lines of force is shown by the intensity ( Fig. 17A and Fig. 17B).

[0081] It could be seen from the Fig. 14A to 15B, how and to what extent the magnetic lines of force of the first and second permanent magnets 30, 32 act on the fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b.

[0082] In addition, by comparing the Fig. 14A to 15B with the results described in the Fig. 16A to 17B, it can be confirmed that the provision of the auxiliary yoke 31 leads to changes in the directions of the magnetic lines of force of the permanent magnets and the distribution of the strength of the magnetic lines of force.

[0083] As in the Fig. 18 to 20, a second embodiment is almost the same as the first embodiment, and differs from it in that the auxiliary yoke is not provided in the magnetic field generating unit 35. It also differs in that the magnetic flux density of the first permanent magnet 30 is made larger than the magnetic flux density of the second permanent magnet 32.

[0084] The same sections are provided with the same reference numbers and their description is omitted.

[0085] In the present embodiment, for example, as shown in the Fig. 18 and Fig. 19, the magnetic flux density of the first permanent magnet 30 is made larger than the magnetic flux density of the second permanent magnet 32. For this reason, a larger magnetic force acts on an arc 111 generated between the fixed contact 24a and the movable contact 87b than on an arc 112 generated between the fixed contact 23a and the movable contact 87a. As a result, when a movable contact piece 81 rotates and returns, the time required for the first permanent magnet 30 to extend the arc 111 generated between the fixed contact 24a and the movable contact 87b to a predetermined length becomes shorter than the time required for the second permanent magnet 32 ​​to extend the arc 112 generated between the fixed contact 23a and the movable contact 87a to a predetermined length.

[0086] In short, the time required for the arc 111 to extend to a predetermined length is shorter than that for the arc 112.

[0087] Accordingly, in the same period of time, the arc 111 generated between the fixed contact 24a and the movable contact 87b can be extended longer than the arc 112 generated between the fixed contact 23a and the movable contact 87. When the arc 111 is attracted to the arc extinguishing space 19 by the first permanent magnet 30 and cut off, the arc 112 is cut off simultaneously because the movable contact 87a and the movable contact 87b are electrically connected to each other. Therefore, the arc 112 can be cut off before it has been extended for a long time.

[0088] If the arc 111 is extended to a sufficient length and can be interrupted early, it is possible to reduce the damage to the insulation in the spaces between the fixed contacts 24a, 23a and the movable contacts 87b, 87a due to the heat generation of the arcs 111, 112. This makes it possible to prevent the arcs 111, 112 from recovering.

[0089] According to the present embodiment, the arc 111 can be extended longer than the arc 112 within the same period of time. For this reason, when the generated arc 111 is extended to a sufficient thickness and can be interrupted before the arc 112 expands, the arc 112 is interrupted at the same time and therefore does not need to be extended for a long time. As a result, a large space is not required for extinguishing the arc 112. In addition, the arc 112 does not come into contact with a plastic mold, thus causing no problem of insulation damage due to the generation of dust and organic gas.

[0090] Therefore, in the present embodiment, it is possible to obtain a small-sized electromagnetic relay in which the problem of insulation damage caused by an arc does not occur even when a large current is allowed to flow.

[0091] As in the Fig. 21 and Fig. As shown in FIG. 22, a third embodiment relates to a case where a stepped portion is provided in the thickness dimensions of the movable contact pieces 80, 81, and the movable contacts 86a, 86b and the movable contacts 87a, 87b, which have the same height dimension, are each fixed. For this reason, a contact-to-contact distance between the fixed contact 21a and the movable contact 86a is larger than a contact-to-contact distance between the fixed contact 22a and the movable contact 86b. Similarly, a contact-to-contact distance between the fixed contact 24a and the movable contact 87b is larger than a contact-to-contact distance between the fixed contact 23a and the movable contact 87a.

[0092] Therefore, as for example in Fig. 22, at the time of rotating and returning the movable contact piece 81 to an operating state, before the separation of the movable contact 87a from the fixed contact 23a, namely, before the generation of the arc 112, the movable contact 87b is separated from the fixed contact 24a and the arc 111 is generated.

[0093] That is, before the arc 112 is generated or at the time of the arc 112 generation, the arc 111 is in the state of having been elongated by the first permanent magnet 30. When the arc 111 is extended to a sufficient length and interrupted by using the arc extinguishing space 19, the arc 112 is interrupted simultaneously because the movable contact 87a and the movable contact 87b are electrically connected to each other. Therefore, the arc 112 can be interrupted before it is elongated.

[0094] When the arc 111 has been extended to a sufficient length and interrupted, it is possible to reduce insulation deterioration in the spaces between the fixed contacts 24a, 23a and the movable contacts 87b, 87a due to heat generation of the arcs 111, 112. This makes it possible to prevent recovery of the arcs 111, 112.

[0095] According to the present embodiment, the distance between contacts can be adjusted by providing only the movable contacts 86a, 86b, 87a, 87b on the movable contact pieces 80, 81 with a stepped portion therebetween. This allows easy adjustment of the timing for generating arc 111 and arc 112.

[0096] That is, if the distance between contacts is set to an appropriate size, the arc 111 can be extended to an appropriate length by the second permanent magnet 32 ​​before the arc 112 is generated. Therefore, when the arc 111 is extended to the appropriate length by the first permanent magnet 30 and interrupted, the arc 112 is interrupted simultaneously because the movable contact 87a and the movable contact 87b are electrically connected to each other. Accordingly, the arc 112 can be interrupted before it is extended. As a result, not much space is required for the arc 112 to be extinguished. In addition, the arc 112 does not come into contact with the plastic mold and does not cause a problem of insulation deterioration due to the generation of dust and organic gas.

[0097] Therefore, according to the present embodiment, it is possible to obtain a small-sized electromagnetic relay in which the problem of insulation deterioration caused by an arc is prevented from occurring by only forming a simple structure of adjusting the distance between the contacts even when a large current is allowed to flow.

[0098] As in the Fig. 23 and Fig. 24, a fourth embodiment relates to a case where a height dimension of the fixed contact 21a is made smaller than a height dimension of the fixed contact 22a and a height dimension of the fixed contact 24a is made smaller than a height dimension of the fixed contact 23a to thereby adjust the distances between the contacts.

[0099] Therefore, the contact-to-contact distance between the fixed contact 21a and the movable contact 86a is greater than the contact-to-contact distance between the fixed contact 22a and the movable contact 86b. Similarly, the contact-to-contact distance between the fixed contact 24a and the movable contact 87b is greater than the contact-to-contact distance between the fixed contact 23a and the movable contact 87a.

[0100] In the present embodiment, as for example in Fig. 24, at the time of rotating and returning the movable contact piece 81 to the operating state, before the separation of the movable contact 87a from the fixed contact 23a, namely, before the generation of the arc 112, the movable contact 87b is separated from the fixed contact 24a, and the arc 111 is generated. Thus, before the generation of the arc 112, or at the time of generation of the arc 112, the arc 111 is in the state of having already been elongated by the first permanent magnet 30. Consequently, when the arc 111 is extended to a sufficient length and interrupted by using the arc extinguishing space 19, the arc 112 is interrupted simultaneously because the movable contact 87a and the movable contact 87b are electrically connected to each other. Therefore, the arc 112 can be interrupted before it is elongated.

[0101] When the arc 111 has been extended to a sufficient length and interrupted, it is possible to reduce insulation deterioration in the spaces between the fixed contacts 24a, 23a and the movable contacts 87b, 87a due to heat generation of the arcs 111, 112. This makes it possible to prevent recovery of the arcs 111, 112.

[0102] According to the present embodiment, it is possible to adjust the distance between contacts by only reducing the height dimensions of the fixed contacts 21a, 24a. This allows for easy adjustment of the timing for generating arc 111 and arc 112.

[0103] That is, if the distance between contacts is set to an appropriate size, the arc 111 can be extended to an appropriate length by the second permanent magnet 32 ​​before the arc 112 is generated. Therefore, when the arc 111 has been extended to the appropriate length and interrupted by the first permanent magnet 30, the arc 112 is interrupted simultaneously because the movable contact 87a and the movable contact 87b are electrically connected to each other. Accordingly, the arc 112 can be interrupted before it is elongated.

[0104] Needless to say, the distance between the contacts can be adjusted by making the height dimensions different between the pair of adjacent movable contacts 86a, 86b or the pair of adjacent movable contacts 87a, 87b.

[0105] In a fifth embodiment, as shown in the Fig. 25 and Fig. 26, by tilting the movable contact piece 80, the contact-to-contact distance between the fixed contact 21a and the movable contact 86a is made larger than the contact-to-contact distance between the fixed contact 22a and the fixed contact 86b. Similarly, by tilting the movable contact piece 81, the contact-to-contact distance between the fixed contact 24a and the movable contact 87b is made larger than the contact-to-contact distance between the fixed contact 23a and the fixed contact 87a. However, the contact-to-contact distance between the fixed contact 21a and the movable contact 86a is the same as that between the fixed contact 24a and the movable contact 87b.

[0106] In the present embodiment, as for example in Fig. As shown in Fig. 26, at the time of rotating and returning the movable contact piece 81 to the operating state, before the separation of the movable contact 87a from the fixed contact 23a, namely, before the generation of the arc 112, the movable contact 87b is separated from the fixed contact 24a, and the arc 111 is generated. Thus, before the generation of the arc 112, or at the time of generation of the arc 112, the arc 111 is in the state of having already been elongated by the first permanent magnet 30. Consequently, when the arc 111 is extended to a sufficient length and interrupted by using the arc extinguishing space 19, the arc 112 is interrupted simultaneously because the movable contact 87a and the movable contact 87b are electrically connected to each other. Therefore, the arc 112 can be interrupted before it is elongated.

[0107] When the arc 111 has been extended to a sufficient length and interrupted, it is possible to reduce insulation deterioration in the spaces between the fixed contacts 24a, 23a and the movable contacts 87b, 87a due to heat generation of the arcs 111, 112. This makes it possible to prevent recovery of the arcs 111, 112.

[0108] According to the present embodiment, it is possible to tilt the movable contact pieces 80, 81 by only performing torsion machining on the movable contact pieces 80, 81, which are already existing components. Thus, there is an advantage in reducing the construction of new manufacturing facilities, thereby avoiding cost increases.

[0109] The status of arc generation in case of applying a high load to the electromagnetic relay according to the above embodiment was measured as follows: Working example 3

[0110] In a working example 3, a measurement was made on the electromagnetic relay according to the second embodiment ( Fig. 18 of 20), in which the additional yoke is not provided and all distances between the contacts are the same.

[0111] The magnetic flux density near the contacts at the time of contact between the fixed contacts 21a, 24a and the movable contacts 86a, 87b by the first permanent magnet 30 was set to 46 mT. The magnetic flux density near the contacts at the time of contact between the fixed contacts 22a, 23a and the movable contacts 86b, 87a by the second permanent magnet 32 ​​was set to 24 mT.

[0112] The fixed contact terminal 22 and the fixed contact terminal 23 were connected to each other via a resistor (not shown), and the arc generation status was measured when a voltage of 1000 V was applied between the fixed contact terminal 21 and the fixed contact terminal 24. Note that the value of the resistor was selected so that a current of 15 A flows in a state where the respective fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b come into contact with each other. The graph of Fig. 27 shows the measurement results.

[0113] In Fig. In Figure 27, "V1" shows a voltage between the fixed contact 21a and the movable contact 86a. "V2" shows a voltage between the fixed contact 22a and the movable contact 86b. "V3" shows a voltage between the fixed contact 23a and the movable contact 87a. "V4" shows a voltage between the fixed contact 24a and the movable contact 87b. In addition, "t1" shows the time from the generation of the arc to the moment of separation between the fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b until the start of the arc extension. "t2" shows the time from the start of the arc extension to the completion of the arc interruption. "t1 + t2" shows the arc life. With regard to “V1”, “V2”, “V3”, “V”, “t1” and “t2”, the following applies to the Fig. 28 and Fig. 29 the same.

[0114] In the graph of Fig. 27, the magnetic flux density of the first permanent magnet 30 was made larger than the magnetic flux density of the second permanent magnet 32, as compared with a later-described Comparative Example 1 ( Fig. 29). It was confirmed that the time "t1" from the generation of the arc to the moment of separation between the fixed contacts 21a, 24a and the movable contacts 86a, 87b until the start of the arc expansion was short.

[0115] In addition, it was confirmed that the arc lifetime "t1 + t2" for each of the arcs between the fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b was short. In addition, according to the graph of Fig. 27, it can also be confirmed that the number of oscillations in the voltage waveform showing the generation, extension, and interruption of the arc during the time “t2” at the time of termination of the oscillations was smaller than the number of oscillations in the voltage waveform in Comparative Example 1.

[0116] Specifically, the number of oscillations in the contact-to-contact voltages "V2" and "V3" between the fixed contacts 22a, 23a and the movable contacts 86b, 87a arranged near the plastic mold were small. Thus, it was found that it is possible to reliably extinguish the arc and reduce the generation of dust and organic gas caused by the arc generation, thereby reliably preventing insulation deterioration. Working example 4

[0117] In a working example 4, a measurement was made on the electromagnetic relay according to the fifth embodiment ( Fig. 25 and Fig. 26) in which the additional yoke is not provided and not all distances between the contacts are the same.

[0118] The magnetic flux density near the contacts at the time of contact between the fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b by the first and second permanent magnets 30, 32 was set to 24 mT. The fixed contact terminal 22 and the fixed contact terminal 23 were connected via a resistor (not shown), and a voltage of 1000 V was applied between the fixed contact terminal 21 and the fixed contact terminal 24 to measure the arc generation status. The graph of Fig. 28 shows the measurement results.

[0119] According to the graph of Fig. 28 were compared with Comparative Example 1 described later ( Fig. 29), the contact-to-contact distances between the fixed contacts 21a, 24a and the movable contacts 86a, 87b were made larger than the contact-to-contact distances between the fixed contacts 22a, 23a and the movable contacts 86b, 87a. Thus, it was confirmed that the arc lifetime "t1 + t2" for each of the arcs between the fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b was short.

[0120] Furthermore, according to the graph of Fig. 28, it can also be confirmed that the number of oscillations in the voltage waveform showing the generation, extension, and interruption of the arc during the time “t2” at the time of termination of the oscillations was smaller than the number of oscillations in the voltage waveform in Comparative Example 1.

[0121] Specifically, the number of oscillations in the contact-to-contact voltages "V2" and "V3" between the fixed contacts 22a, 23a and the movable contacts 86b, 87a arranged near the plastic mold were small. Thus, it was found that it is possible to reliably extinguish the arc and reduce the generation of dust and organic gas caused by the arc generation, thereby reliably preventing insulation deterioration. Comparison example 1

[0122] In Comparative Example 1, the arc generation status was measured under conditions similar to those described above with respect to Working Example 3, except that the magnetic flux density in the vicinity of the contacts at the time of contacting between the fixed contacts 21a, 22a, 23a, 24a and the movable contacts 86a, 86b, 87a, 87b by the first and second permanent magnets 30, 32 was set to 24 mT. The graph of Fig. 29 shows the measurement results.

[0123] According to the graph of Fig. 29, it was confirmed that the arc lifetime “t1 + t2” for each of the arcs generated between the movable contacts 86a, 86b, 87a, 87b and the opposing fixed contacts 21a, 22a, 23a, 24a was longer than the arc lifetime “t1 + t2” in Working Examples 3, 4. Accordingly, it was found that the arc lifetime can be reduced by appropriately varying the magnetic flux density or the spacing of the contacts.

[0124] In addition, the number of oscillations in the voltage waveform showing the generation, extension, and interruption of the arc during the time “t2” was larger than the number of oscillations in Working Examples 3, 4. More specifically, the numbers of oscillations of the contact-to-contact voltages “V2”, “V3” between the fixed contact 22a and the fixed contact 23a located near the plastic mold were significantly larger than the number of oscillations in Working Examples 3, 4. It was deduced from this fact that the arc was repeatedly generated, extended, and interrupted a number of times. Working example 5

[0125] The fixed contact terminal 22 and the fixed contact terminal 23 of the electromagnetic relay according to the second embodiment ( Fig. 30) were connected together through a resistor not shown, and a voltage of 1000 V was applied between the fixed contact terminal 21 and the fixed contact terminal 24 to perform an opening and closing test to measure the arc generation status.

[0126] Specifically, a voltage between the contacts was measured by an oscilloscope to obtain a waveform showing voltage changes between the contacts. Furthermore, the generated arc was photographed by a high-speed camera, and the photographed image of the arc was subjected to image processing to measure the length of the arc. The arc length was then plotted on a waveform of the voltage between the contacts to obtain a graph ( Fig. 31) which shows the relationship between the arc lifetime, the voltage between the contacts and the arc length.

[0127] Out of Fig. 31 it was confirmed that the following cycle is repeated: The Fig. The movable contact piece 80 shown in Fig. 30 is rotated in the direction from the operating position to the return position, and when the movable contact 86a is separated from the fixed contact 21a, an arc 111A is generated, and an arc 111B extended by the permanent magnet 30 is interrupted. It was also confirmed that there is a correlation between the voltage between the contacts and the arc length.

[0128] More specifically, when a high voltage is applied, at the time of separation of the movable contact 86a from the fixed contact 21a, the arc 111A is generated between the fixed contact 21a and the movable contact 86a. At an initial stage of the separation process, as the distance between the contacts increases, the arc 111A lengthens in proportion to this increase, and the arc 111A reaches an arc length nearly equivalent to the distance between the contacts (about 3 mm).

[0129] Thereafter, the arc 111A is elongated by the magnetic force of the first permanent magnet 30 and expanded to a length greater than the contact-to-contact distance between the fixed contact 21a and the opposing movable contact 86a to become the arc 111B. When the insulation resistance in the space where the arc 111B exists becomes greater than the insulation resistance in the space between the fixed contact 21a and the opposing movable contact 86a, the new arc 111A is generated between the first contact 21a and the movable contact 86a. Simultaneously, the elongated arc 111B is cut off. The generated new arc 111A is then expanded by the magnetic force of the first permanent magnet 30 in the same manner as described above. Thereafter, the phenomenon of generation of the arc 111A and cutting off or cutting off is eliminated.interrupting the extended arc 111B in a similar cycle as that described above.

[0130] Normally, an electromagnetic relay ( Fig. 19) having a double breaker contact structure as in the second embodiment, when the movable contact piece 80 is rotated, the arcs 111, 112 are generated simultaneously between the movable contacts 86a (87b) and the fixed contacts 21a (24a) and between the movable contacts 86b (87a) and the fixed contacts 22a (23a) and expanded in the same manner.

[0131] However, in the electromagnetic relay according to the second embodiment, the arc 112 easily comes into contact with the resin mold disposed near the fixed contacts 22a (23a), and therefore, dust or an organic gas is easily generated. When the dust or organic gas is generated by the arc 112 coming into contact with the resin mold, insulation deterioration occurs in the internal space and causes a drop in insulation resistance. Accordingly, the arc 112 is more easily generated between, for example, the movable contacts 86b (87a) and the fixed contacts 22a (23a). As a result, even after a complete return of the movable contacts 86a, 86b, the arcs 111, 112 are repeatedly generated, extended, and interrupted, and the time required for the arcs 111, 112 to be completely interrupted becomes long.This causes a vicious cycle of the generated arc being repeatedly brought into contact with the plastic mold, generating dust or an organic gas and shortening the life of the contact.

[0132] Accordingly, based on the above knowledge, the present inventors preferentially attracted and expanded the arc 111 generated between the movable contacts 86a (87b) and the fixed contacts 21a (24a) near which the plastic mold is not disposed by the magnetic force of the first permanent magnet 30, and interrupted the arc early. Therefore, even if the arc 112 is generated between the movable contacts 86b (87a) and the fixed contacts 22a (23a) near which the plastic mold is disposed, the arc 112 can be interrupted simultaneously with the arc 111 before the arc 112 expands. Therefore, the present inventors were able to prove that the problem caused by the generation of the arc 112 can be solved and realized the present invention. INDUSTRIAL APPLICABILITY

[0133] The present invention is not limited to a DC electromagnetic relay, but can also be applied to an AC electromagnetic relay.

[0134] Although the cases of application of the present invention to the electromagnetic relay having four poles have been described in the above embodiments, this is not limitative, and it can be applied to an electromagnetic relay having at least one pole.

[0135] Needless to say, the present invention is applicable to an electromagnetic relay having two or more poles where two or more movable contacts are provided on one movable contact piece.

[0136] Furthermore, the present invention is not limited to the electromagnetic relay, but can also be applied to a switch. REFERENCE NUMBER LIST 10 Base 10a engagement claw section 11 Recess section 12 Partition wall 13 step section 14 Press-in hole 15a,15b,15c,15d connection hole 16a,16b connection hole 17 notched groove 18 Recess section 19 Bow extinguishing room 21-24 fixed contact connection 21a-24a fixed contact 25 Coil connection 25a connecting section 25b connecting section 30 first permanent magnet 31 Additional yoke 32 second permanent magnet 35 Magnetic field generation unit 40 electromagnetic block 41 coil bodies 42,43 Flange section 44 fuselage section 45 through hole 46 Insulation rib 47 access hole 50 relay claw 51 coil 52 iron core 53 Magnetic pole section 55 yoke 60 movable iron piece 70 spacers 71 Recess section 72 Insulation rib 73 Insulation rib 74 movable stage 80 movable contact piece 81 movable contact piece 82 large section 83 Large Width Section 84 covering element 85 covering element 86a,86b movable contact 87a,87b movable contact 90 lids 91 Gas outlet hole 92 Intervention receiving section 93 Position adjustment rib 100 sheet cutting element 101 Lead 102 Rib 103 Rib 104 Tongue element 110 sheets 111 sheets 111A Bow 111B Bow 112 sheets

Claims

[1] Electromagnetic relay, characterized by that it includes: a first movable contact (86a, 87b) and a second movable contact (86b, 87a) arranged on a movable contact piece (80, 81), a first fixed contact (21a, 24a) and a second fixed contact (22a, 23a) arranged to be contactable and separable from the first movable contact (86a, 87b) and the second movable contact (86b, 87a), respectively; and a magnetic field generating unit (35) arranged to attract an arc generated between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) and an arc generated between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a) in a predetermined direction, in which, when a predetermined period of time has elapsed after the generation of an arc at least either between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) or between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a), an arc generated between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) is elongated by the magnetic field generating unit (35) so that it is longer than an arc generated between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a). [2] Electromagnetic relay, characterized by that it includes: a first movable contact (86a, 87b) and a second movable contact (86b, 87a) arranged on a movable contact piece (80, 81), a first fixed contact (21a, 24a) and a second fixed contact (22a, 23a) arranged to be contactable and separable from the first movable contact (86a, 87b) and the second movable contact (86b, 87a), respectively; and a magnetic field generating unit (35) arranged to attract an arc generated between the first movable contact (86a, 87a) and the first fixed contact (21a, 23a) and an arc generated between the second movable contact (86b, 87b) and the second fixed contact (22a, 24a) in a predetermined direction, wherein the magnetic flux density of the magnetic field generating unit (35) is adjusted such that the magnetic flux density between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) is greater than the magnetic flux density between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a). [3] Electromagnetic relay, characterized by that it includes: a first movable contact (86a, 87b) and a second movable contact (86b, 87a) arranged on a movable contact piece (80, 81), a first fixed contact (21a, 24a) and a second fixed contact (22a, 23a) arranged to be contactable and separable from the first movable contact (86a, 87b) and the second movable contact (86b, 87a), respectively; and a magnetic field generating unit (35) arranged to attract an arc generated between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) and an arc generated between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a) in a predetermined direction, wherein the contact-to-contact distance between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) at the time of contact separation is made larger than the contact-to-contact distance between the second movable contact (86b, 87a) and the second fixed contact (22a, 23a) at the time of contact separation. [4] Electromagnetic relay according to claim 3, characterized by that the shape of the movable contact piece (80, 81) is selected such that the distance from the movable contact piece (80, 81) to the first fixed contact (21a, 24a) is greater than the distance from the movable contact piece (80, 81) to the second fixed contact (22a, 23a). [5] Electromagnetic relay according to claim 3, characterized by that the height dimension of the first fixed contact (21a, 24a) is made smaller than the height dimension of the second fixed contact (22a, 23a). [6] Electromagnetic relay according to claim 3, characterized bythat the height dimension of the first movable contact (86a, 87b) is made smaller than the height dimension of the second movable contact (86b, 87a). [7] Electromagnetic relay according to one of claims 1 to 6, characterized by that the arc generated between the first movable contact (86a, 87b) and the first fixed contact (21a, 24a) is attracted and extended towards an arc extinguishing space (19) arranged in a direction which, as seen from the first movable contact (86a, 87b) or the first fixed contact (21a, 24a), is opposite to the opposite first fixed contact (21a, 24a) or the opposite first movable contact (86a, 87b).

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