ELECTROMAGNETIC RELAY

Abstract: An electromagnetic relay includes a coil assembly 2 with a coil 20 and an ion core 21 extending through the coil 20, an ar­ mature assembly with a pair of frame-shaped upper and lower armatures 3, 4 disposed parallel to each other and so as to sur­ round the coil 20, and a pair of contact units 6, 8 operated by the armature assembly. The coil 20 is covered with a molded portion 23 which has a pair of lateral studs 24 integrally formed with it, the studs 24 defining a horizontal axis about which the armature assembly is pivotal. High accuracy in the positional relation between the pole faces formed by extending ends of the iron core 21 and the respective ends of the armatures 3, 4 cooperating with the pole faces is achieved by the fact that both the pole faces provided on the iron core 21 and the studs 24 form part of the coil assembly which is formed as one com­ mon block. At the same time, a very thin relay is obtained since the overall vertical dimension of the relay may be restricted to the height of the coil.

Description: Electromagnetic Relay DESCRIPTION: This invention relates to an electromagnetic relay, particularly to a balanced armature type polarized relay having four air gaps. A conventional four-gap balanced armature type polarized relay includes a pair of armatures pivotally supported above or below a coil for rotation in a horizontal plane, which inevitably creates the problem that the overall vertical dimension of the relay becomes large. Further, the shafts for supporting the armatures are disposed on a member which is separate from the coil, so that the relative positional accuracy between the coil and the axis of the shafts, thus between the end portions of an iron core extending through the coil and the armatures cooperating with these end portions is limited, thus involving the problem that a desired relay characteristic is difficult to reproduce. Also, contact springs driven by the armatures are often restricted with respect to their disposition so that the design of multi-contacts has been difficult. It is an object of the present invention to provide a balanced armature type relay which is thin in its vertical dimension, which exhibits high accuracy in the positional relation between the armatures and the end portions of the iron core, thereby achieving stable relay characteristics, and which provides a high degree of freedom in the disposition of the movable contacts, thereby facilitating the provision of multi-contacts. Also, the relay is to be sealed in a casing with high sealing effect and should exhibit high withstand voltage between the coil and the contacts. In view of the above object, the present invention provides an electromagnetic relay comprising the features specified in claim 1. Accordingly, since the pair of rectangular frame-shaped armatures surround the coil and are supported for pivotal movement about a horizontal axis defined by the studs, the overall structure has a vertical dimension limited to the height of the coil assembly. Also, a multi-contact structure is easily obtained since the contact springs are positioned laterally of the coil assembly in parallel to any side of the rectangular armatures, either between them or on the outer surfaces thereof. In the development of claim 2, since the studs are integral with the coil assembly, the positional relation between the armatures and the end portions of the core extending through the coil is reproducible with close tolerances. Substantially the same accuracy can be achieved in the development of claim 3 where the studs supporting the armatures are formed in a housing frame of the relay which positions the coil assembly. A magnetic shielding between the coil and the contacts is achieved in the development of the invention as set forth in claim 8. A particularly effective sealing of the relay in an outer casing is obtained in the further development of the invention called for in claims 11 and 12, according to which the connecting surfaces between casing portions are large and a sealing agent accordingly spreads over a large area. In addition, if the individual casing portions should have different contraction rates, compression occurs between parts of the mutually engaging surfaces, thereby enhancing the sealing effect. In a further advantageous development of the invention according to claims 13 and 14, when the casing portions are sealed together, insulation at the connecting parts of coil terminals is improved by a capillary action of the sealant, thereby improving the insulation between the coil and the contacts to increase the breakdown voltage of the relay. Preferred embodiments will now be described with reference to the drawings in which Fig. 1 is a perspective exploded view of a polarized, balanced armature type relay, Fig. 2 is a plan view of the relay of Fig. 1 in its assembled condition with the upper cover and upper armature removed, Fig. 3 is a sectional view of the relay taken along the line A-A of Fig. 2 with the lower armature and lower cover also omitted, Fig. 4 shows a vertical section through the coil and armature assemblies and the movable contact springs to show the positional relation between these elements, Fig. 5 is a detailed view of a fixed contact of the relay, Fig. 6 is a cross-sectional view through the relay showing a part of the casing and coil assembly, Fig. 7 shows another cross-section through the casing of the relay, Fig. 8 is a perspective exploded view similar to Fig of a modified balanced armature type polarized relay, Fig. 9 is a perspective exploded view of the lower armature and one permanent magnet for explaining another mode of interconnecting these elements in the relays according to Figs. 1 and 8, Fig. 10 is a side view of the pair of armatures and the permanent magnets according to the embodiment of Fig. 9, shown during assembly, Fig. 11 is a perspective exploded view of the coil and armature assemblies according to another embodiment of the invention, and Fig. 12 is a side view of the coil and armature assemblies of Fig. 11, shown in the assembled condition. The relay shown in Figs. 1 to 7 comprises a casing 1 including a rectangular frame member 11 and upper and lower covers 9 and 10. As shown in detail in Fig. 7, the lower rim of the upper cover 9 and the upper rim of the lower cover 10 are each provided with a groove 19, and projecting ridges 13 fitting into the grooves 19 are provided on the top and bottom edges of the frame 11. The contact surfaces between the frame 11 and each of the covers 9 and 10 is thus rather large, thus providing a large area over which sealant 53 can spread. If there is a difference in the contraction rates between the frame 11 and the covers 9 and 10, either of the side surfaces of the ridge 13 will be inevitably subjected to compression by the corresponding surface of the groove 19, thereby enhancing the sealing effect. Rather than forming ridges 13 on the frame 11, as shown in Fig. 7, it is also possible to provide ridges on the covers 9 and 10 and corresponding grooves in the frame 11. As best seen in Figs. I to 3, the frame 11 carries a pair of movable contact springs 6 and fixed contacts 8, the free end of each spring 6 having a contact portion 7 for cooperation with the respective fixed contact 8. A plurality of terminals 14 is embedded in the frame 11, each terminal 14 having a connecting portion extending to the outside of the frame 11, and an inner connecting portion for engagement with a corresponding connecting portion of the coil and contacts. Two of these inner connecting portions 51 of two corresponding terminals 14 are shown in Fig. 1. A coil assembly generally referenced by numeral 2 includes a coil 20 wound on a bobbin 22 and an iron core 21 extending through the bobbin and coil. End portions of the core 21 extend to the outside at both ends of the bobbin 22 and are each provided with a recess 25. The coil 20 is covered by a molded portion 23, and in applying this molded portion, the core 21 is held at the upper and lower surfaces of the core end portions, the molded portion 23 being formed integrally with a pair of studs 24 projecting laterally from both sides of the coil 20. By this process, high positional accuracy between the end portions of the core 21 and the studs 24 is ensured inspite of the fact that the studs 24 are disposed on the outer periphery of the coil 20. The coil assembly 2 is inserted into the frame 11 in fitting projections 12 formed at the inner surfaces of the frame 11 into the grooves 25 at the end faces of the core end portions. This structure improves the mechanical strength of the frame 11 by using the iron core 21 as a central portion thereof. As further shown in Fig. 1, upper and lower armatures 3, 4 of flat, rectangular frame-shape are provided. A rectangular frame-like balancing spring 35 is mounted on the upper surface of the upper armature 3. A pair of permanent magnets 5 is disposed at opposite sides on the upper surface of the lower armature 4, each magnet 5 being located between a pair of connecting pins 41 extending from the lower armature 4. The lower surface of the upper armature 3 and the upper surface of the lower armature 4 are provided with integrally formed actuating noses 31 disposed opposite each other at an end of respective edges of the armatures. Bearing members 30 are provided at the centers of both sides of both armatures 3, 4 at the inner edges of their frame-shapes so as to project upwardly from the lower armature 4 and downwardly from the upper armature 3. In assembling, the armatures 3, 4 are disposed so as to surround the coil assembly 2, which itself has been mounted in the frame 11. The connecting pins 41 projecting upwardly from the lower armature 4 are fitted into bores 32 in the upper armature 3 thereby connecting the two armatures 3, 4 so that they are maintained parallel to each other. At the same time, the two pairs of upper and lower bearing members 30 provided at both armatures 3, 4 sandwich the pair of studs 24 extending from the molded portion 23 of the coil assembly 2, and the pair of permanent magnets 5 abut with their upper surfaces against the lower surface of the upper armature 3. The thus completed armature assembly is supported for pivotal movement about the horizontal axis defined by the pair of studs 24. The contact springs 6 are sandwiched between the opposing actuating noses 31 provided at the inner surfaces of the upper and lower armatures 3, 4. Also, the contact units formed by the contact springs 6 and the fixed contacts 8 are disposed within a shielded space S enclosed by the permanent magnets 5 and the upper and lower armatures 3, 4 as shown in Fig. 4. Thus, the coil 20 and the contact units are magnetically shielded from each other so that surges from the contact side (output side) are prevented from influencing the coil side (input side), in other words, the electronic circuit at the input side is protected against being damaged by surges occurring at the output side. In Fig. 4, the molded portion 23 of the coil assembly 2 is not shown. After the coil assembly 2 has been inserted in the frame 11 and the armature assembly has been completed around the coil assembly and the contact units, the casing is closed by placing the upper and lower covers 9, 10 on the respective edges of the frame 11 with sealant being disposed between the contacting surfaces of these casing portions as explained above. As shown in Fig. 1, the coil 20 has its wire ends connected to coil connecting portions 50 which project laterally from the ends of the core 21 extending from the coil. In the embodiment shown, a double-coil has been assumed, so that there are four coil connecting portions 50. When the coil assembly 2 is inserted into the frame 11, these coil connecting portions 50 come into engagement with portions 51 which are the inner ends of terminals 14. The engaging condition between these connecting portions 50 and 51 is shown in detail in Fig. 6. As is also indicated in Figs. 1 and 6, ribs 52 are formed integrally with said upper and lower covers 9, 10 so as to project inwardly with each rib 52 of the upper cover 9 facing a corresponding rib of the lower cover 10 at a position corresponding to the connecting portions 50 and 51. When the casing 1 is closed and the casing portions 9, 10 and 11 are bonded together by means of the sealant 53, the inner ends of the ribs 52 come in close proximity to the respective outer surfaces of the connecting portions 50, 51, and the gap therebetween is filled with the sealant due to capillary action. The insulation between the coil 20 and the contact terminals 14 is thus improved, and the breakdown voltage is increased without increasing the overall number of component parts of the relay or the number of steps in the process of manufacturing and assembling such relay. In operation of the relay, when voltage is applied to the coil 20 to magnetize the upper and lower surfaces (pole faces) at both projecting ends of the iron core 21, magnetic attractive and repulsive forces are created between the ends of the core and the corresponding ends of the armatures 3, 4 which are magnetized by the permanent magnets 5. The armature assembly is thereby caused to pivot about the axis defined by the studs 24, thereby driving the contact springs 6 sandwiched between the actuating noses 31 into or out of engagement with the corresponding fixed contacts 8, respectively. Adjustment of the switching characteristics of the relay by positioning the fixed contacts 8 will now be explained with reference to Figs. 2, 3 and 5. Each fixed contact 8 is mounted on a pole plate 15 which has a pair of lugs 16 projecting from both sides at the central portion of the plate 15, as specifically shown in Fig. 2. These lugs 16 are embedded in a portion of the frame 11 and connected to a respective one of the terminals 14. The fixed contact 8 is mounted at a front end of the plate 15 at a position in which it opposes the contact portion 7 provided on the contact spring 6, whereas the rear end of the plate 15 projects beyond the tip of the spring 6. As shown in Fig. 3, an adjusting tool 17 may be used to press on the rear end of the plate 15 from above or below to rotate the plate 15 about a horizontal axis defined by the lugs 16 thereby varying the vertical position of the fixed contact 8, as shown in Fig. 5. As will be appreciated from the above description, the studs 24 supporting the armature assembly are integral with the molded portion 23 covering the coil 20 so that the iron core 21 penetrating through the coil 20 and the studs 24 are in a fixed position relatively to each other and form a common block to be conveniently assembled and inserted into the relay frame 11. The relative position between the upper and lower surfaces provided at both ends of the iron core 21, which serve as the pole faces, and the end surfaces of the armatures 3 and 4 cooperating with these pole faces is thus reproduced with high accuracy, so that stable relay characteristics are obtained. Moreover, the pair of armatures 3, 4 and the contact units 6 are disposed at the lateral sides of the coil 20, so that the vertical dimension of the entire mechanism may be restricted to the height of the coil 20. Accordingly, a relay of thin structure is devised, without imposing restrictions on the coil design which may thus be wound with maximum efficiency. In addition, since the coil is covered by the molded portion 23, the contacts 7, 8, are not affected by gases or moisture from the coil winding. The modified embodiment of the invention shown in Fig. 8 differs from that described above in that the bearing members 30 are formed near the outer edges of only the lower armature 4 outside the permanent magnets 5. The bearing members 30, the connecting pins 41 and the actuating noses 31 are integrally molded with the armatures 3, 4. Bearing studs 241 of semi-circular cross-section extend between opposite inner surfaces of the frame member 11 and webs 46 integrally disposed within the frame member 11. Thus, the studs 24' are supported at both of their ends so that they have high strength and dimensional stability. At the same time, the existence of the webs 46 and their connection to the respective inner surfaces of the frame member 11 through the studs 241 increase the strength and dimensional stability of the frame member 11. The upper and lower armatures 3, 4 are pivotally supported by placing the frame-like balancing spring 35 at two sides thereof on the projections 12 molded to opposite inner sides of the frame member 11, and bringing the semi-circular cut-outs in the pair of bearing members 30 on the lower armature 4 in contact with the semicircular lower bearing surfaces of the studs 24'. Figs. 9 and 10 show another way of connecting the permanent magnets 5 between the upper and lower armatures 3, 4, which structure may be employed in either of the relays according to Figs. 1 to 8. The permanent magnets 5 serve as spacers defining the interval between the upper and lower armatures 3, 4 and employ iron alloy magnets of the alnico series (Fe-Ni-Co) or the Fe-Cr-Co series. The mutually facing inner surfaces of the armatures 3, 4 are provided with sockets 36 of thermoplastic synthetic resin providing a wall for surrounding the mounting faces of the permanent magnets 5. When the magnets 5 are welded to the armatures 3, 4 by means of welding electrodes shown in Fig. 10, blast debris at high temperature which are ejected from the welding location strike against the inner socket walls and are thus prevented from scattering to the outside. Projections 37 are provided on the magnet mounting faces of the armatures, which projections serve to stabilize the welding process. Compared to the connecting pins 41 shown in the embodiments of Figs. 1 and 8, the welded connection explained with reference to Figs. 9 and 10 provides improved dimensional stability and strength and increased working efficiency of the armature assembly. The further embodiment shown in Figs. 71 and 12 differs from those described above in that the flat, rectangular frame-shaped upper and lower armatures 3, 4 are interconnected at two opposite ends by brackets 18 each of which has an integrally molded stud 24". The studs 24" define a pivot axis for the armature assembly which extends along the axis of the coil 20. The studs 24" are supported by bearing members (not shown) which may be provided at opposite inner walls of the frame member 11. As in the previous embodiments, two permanent magnets 5 are disposed between the upper and lower armatures 3, 4 to magnetize them with opposite polarities. Both end portions of the iron core 21' extending from the coil 20 are bent perpendicularly to the coil axis to opposite sides. Contact springs (not shown) driven by the armature assembly are disposed parallel to any side of the armatures outside the same. If the armatures are dimensioned so as to extend beyond the permanent magnets 5, as shown in phantom lines in Fig 12, the contact springs may be disposed between the armatures in a manner similar to that shown in Fig. 4.

Claims: CLAIMS: 1. An electromagnetic relay comprising a coil assembly (2) including a coil (20) and a core (21) penetrating through the coil and having end portions extending from the coil, an armature assembly including a pair of upper and lower armatures (3, 4) of rectangular frame-shape surrounding said coil (20) and having end portions disposed opposite said core end portions, the armature assembly being pivotal about an axis defined by a pair of studs (24), and at least one contact unit (6, 8) positioned laterally of said coil assembly (2) and including a fixed contact (8) and a movable contact (6) operated by said armature assembly for cooperation with the fixed contact. 2. The relay of claim 1, wherein said coil assembly (2) is covered by a molded portion (23), said pair of studs (24) being integrally formed at opposite sides of the molded portion so that said pivot axis of the armature assembly extends transversely of the coil axis. 3. -The relay of claim 1, wherein said pair of studs (24') are formed inside a housing frame member (11) of the relay positioning the coil assembly (2) so that the pivot axis of said armature assembly extends transversely of the coil axis. 4. The relay of claim 3, wherein each stud (24') extends between an inner wall of said frame member (11) and a web (46) provided integrally with the frame member. 5. The relay of claim 1, wherein said studs (24") are provided on brackets (18) interconnecting said upper and lower frames (3, 4) so that the pivot axis of said armature assembly extends along the coil axis, said core end portions being bent so as to extend transversely of the coil axis. 6. The relay of any of claims 1 to 5, wherein said armature assembly includes at least one permanent magnet (5) disposed between said upper and lower armatures. 7. The relay of claim 1, wherein said at least one permanent magnet (5) is welded to the inner surface of at least one of said upper and lower armatures (3, 4) inside a socket wall (36) of synthetic resin surrounding the surface portion of the armature to which said magnet is welded. 8. The relay of claim 6 or 7, wherein said movable contact includes a contact spring (6) disposed within a space (S) defined by said upper and lower armatures (3, 4) and said permanent magnet (5) and located on that side of the permanent magnet which faces away from said coil assembly (2). 9. The relay of claim 8, wherein said upper and lower armatures (3, 4) have nose portions (31) formed on the surfaces facing each other for actuating said contact spring (6). 10. The relay of any of claims 1 to 4, wherein each of said upper and lower armatures (3, 4) has means (30) which together form a pair of bearings for receiving said pair of studs (24). 11. The relay of any of claims 1 to 10, further comprising a casing (1) including a frame member (11) mounting said coil assembly (2) and contact unit (6, 8) and having terminals (14) connected to said coil and said contact unit and extending to the outside of the frame member, and upper and lower covers (9, 10) having peripheral portions engaging opposite edges of the frame member for sealingly enclosing said coil and armature assemblies and contact unit. 12. The relay of claim 11, wherein in either pair of mutually engaging cover peripheral portion and frame edge one has a projection (13) and the other has a groove (19) receiving the projection, with a sealant (53) being inserted between said groove and projection. 13. The relay of claim 11, 12, wherein said coil (20) has at least two end portions (50) and at least two of said terminals (14) have inner end portions (51) connected to said coil end portions, and wherein ribs (52) are formed integrally with said upper and lower covers (9, 10) adjacent said frame member (11) so as to project inwardly of said casing (1) and approach outer surfaces of said interconnected coil and terminal end portions (50, 51). 14. The relay of any of claims 11 to 13, wherein said core end portions have recesses (25) and said frame member (11) has integrally formed inner projections (12) engaging said recesses.

Inventors: MOTOYAMA, MASANORI, NISHIKAWA, TOYOTAKA
Applicants: MATSUSHITA ELECTRIC WORKS, LTD., SAUER, HANS
Application year: 1984
Main classification: H01H51
IPC codes: H01H50, H01H51