US3684986A

US3684986A - Electromagnetic relay

Info

Publication number: US3684986A
Application number: US136508A
Authority: US
Inventors: Mitsuki Nagamoto; Yutaka Sato
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 1970-04-22
Filing date: 1971-04-22
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15
Also published as: DE2118633B2; DE2118633A1

Abstract

An improved electromagnetic relay including a movable contactor arm made of a conductive rigid plate material. The arm is bent upward adjacent the opposite end to the movable contactor end thereof and supported rockably on a bottom face having a tapered section at the contactor side of an insulative arm-supporting frame secured on the armature for integral actuation therewith. The frame includes a spring for biasing the arm downward at a position between the tapered corner of frame bottom and the bent corner of the arm, so that, in non-excited state of electromagnet, the movable contactor is urged against a normally closed contact by the downward biasing applied with the tapered corner as fulcrum and, in excited state, the contactor is urged reversely against a normally opened contact by the same biasing applied with the bent corner as fulcrum. The frame may include forcibly opening means for contacts adjacent both the tapered and bent corners.

Description

United States Patent Nagamoto et al.

ELECTROMAGNETIC RELAY Inventors: Mitsuki Nagamoto; Yutaka Sato,

both of Tsu-shi, Japan Assignee: Matsushita Electric Works, Ltd.,

Osaka, Japan Filed: April 22, 1971 Appl. No.: 136,508

Foreign Application Priority Data April 22, 1970 Japan ..45/34598 May 13, 1970 Japan ..45/46561 May 26, 1970 Japan ..45/52110 US. Cl ..335/200, 335/187 Int. Cl. ..Hlllh l/l2 Field of Search ..335/202, 203, 135, 128, 187,

335/196, 200; 200/166 J, 67 PK References Cited UNITED STATES PATENTS Aug. 15, 1972 2,870,282 1/1959 Brand 200/67 PK Primary Examiner-Harold Broome AttorneyWolfe, Hubbard, Leydig, Voit & Osann 5 7] ABSTRACT An improved electromagnetic relay including a movable contactor arm made of a conductive rigid plate material. The arm is bent upward adjacent the opposite end to the movable contactor end thereof and supported rockably on a bottom face having a tapered section at the contactor side of an insulative arm-supporting frame secured on the armature for integral actuation therewith. The frame includes a spring for biasing the arm downward at a position between the tapered corner of frame bottom and the bent corner of the am, so that, in non-excited state of electromagnet, the movable contactor is urged against a normally closed contact by the downward biasing applied with the tapered comer as fulcrum and, in excited state, the contactor is urged reversely against a normally opened contact by the same biasing applied with the bent corner as fulcrum. The frame may include forcibly opening means for contacts adjacent both the tapered and bent comers.

6 Claims, 6 Drawing Figures PAIENTEDAus 1 5 m2 SHEU 2 0F 3 mvswons Ml Tau/(1 nomoro BY VUTAKA Snro ATTORNEYS W05 5AM 04 ELECTROMAGNETIC RELAY This invention relates to an electromagnetic relay.

Conventional electromagnetic relays of this kind have been of such structure that the movable contact provided on the contact arm of elastic conductive material has been provided between fixed contacts. Since such movable contact arm has been made of an elastic material, the use of thick material might reduce elasticity of the material and, therefore, it has been impossible to increase current capacity of the movable contact arm.

Further, in the case when there occurs a fusing trouble between the movable contact and either one of the fixed contacts and thereby the both contact points are fused together, it is necessary to forcibly open such fused contact points by a proper means. However, since in the conventional relays the movable contact arm is elastic and, thus, even a forcibly opening mechanical means is provided for such fused contacts the intended opening operation of the means is caused to be not reliable or even not effective due to the elasticity of the contact arm which will absorb the force of such means.

The present invention is proposed to obviate the above mentioned drawbacks and solves the problems in that a rigid conductive member is used as the movable contact arm and the member is biased by a spring to apply proper contact pressure thereto against the fixed contact.

It is, therefore, a principal object of the present invention to provide an electromagnetic relay of small size and yet of a high capacity.

Another object of this invention is to provide an electromagnetic relay which is easy to assemble on account of simple structure adapted to support the movable contact arm.

It is a further object of the present invention to provide an electromagnetic relay which performs stable and reliable relaying operation even when movable and fixed contacts are fused together, which fused contacts will be positively opened with a forcible opening means for such fused contacts provided in addition to the above described combination of the rigid contact arm and the biasing spring.

Other objects and advantages will be made clear as the following detailed disclosures advance with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an embodiment of the electromagnetic relay according to the present invention;

' FIGS. 2A and 2B are sectional views of the electromagnetic relay in FIG. 1, and FIG. 2A shows nonexcited state of the electromagnet and FIG. 2B shows excited state of the same;

FIG. 3 is an exploded perspective view of the movable contact mechanism in the relay shown in FIG. 1; and

FIGS. 4A and 4B shown in fragmental sections another embodiment in which a fused contact forcibly opening means is provided, FIG. 4A showing an operating state of said means in which normally closed fixed contact and movable contact are fused together and do not open even the electromagnet is excited, and FIG. 48 showing another operating state of the means in which normally opened fixed contact and the movable contact are fused together and do not return to the normally open state even the excitation of the electromagnet is interrupted.

The present invention will now be disclosed with reference to preferred embodiments as illustrated, but it is not the intention to limit the invention to such particular embodiments. It should be appreciated that the intention is rather to include all alterations, modifications and equivalents within the scope of appended claims.

In the drawings, 1 designates a base plate made of insulating material, on one side of which are integrally provided a normally closed terminal 2, a normally opened terminal 3, a common terminal 4 and coil terminals 5, and said

terminals

2 and 3 extend through the base plate 1 to form normally closed fixed contact 6 and normally opened fixed contact 7 on the opposite side of the base plate 1. In the drawing, four pairs of fixed contacts are shown (FIG. 1). 8 is a partition provided between adjacent pairs of the contacts. 9 is a movable contact arm and 10 is a movable contact provided thereon.

11 indicates an electromagnet, whose yoke 12 formed substantially in a U-shape in section is secured to the base plate 1 at its one of its upright legs. 13 is an armature provided with a notch 14 at each corner of one side thereof, and a projection 15 provided at end portion of the other upright leg of the U-shaped yoke 12 engages in said notch 14 to rotatably support the armature 13 above the yoke. 16 is a projection formed at said side of the armature 13 adjacent each of the notches 14, at which an end of a tension spring 17 engages. The other end of the spring 17 is engaged in a hole 18 provided in the yoke 12.

19 is a lower frame made of an insulating material and secured at its bottom face to the upper face of the armature 13. 20 is an upper frame mating with the lower frame 19. Said lower and

upper frames

19 and 20 constitute a holding frame 39 as assembled together. The base portion of the movable contact arm 9 is inserted into and held between the upper frame 20 and the lower frame 19.

Next, the structure of the upper and the lower frames will be described in more details.

In FIG. 3, showing a movable contact assembly including two contact arms, the upper frame 20 is formed substantially in reverse U shape in section so as to be provided with a U-shaped groove 21. The frame 20 is further provided at the central portion of respective lateral downward wall portions with downwardly extending legs 22. Inside the tip of each leg 22, there is provided inward projection 23.

Walls

24, 25 and 26 are formed in parallel to each other on the both sides and central portion of the lower frame 19 and an upward projection is formed on each of said walls to allow them to engage in the U-shaped groove of the upper frame 20. A pair of engaging holes 27 are provided at both side ends of the central wall 25 for receiving therein the legs 22 and inward projections 23 of the upper frame 20, and

vertical grooves

28, 29, 30 and 31 are formed respectively at each inside surface of the

respective walls

24, 25 and 26. 32 is a straight bottom section provided on the bottom surface in each channel between said walls of the lower frame 19, and a tapered portion is formed on one side of the bottom portion 32 so as to be inclined toward the contacts.

9 is a movable contact arm made of conductive rigid material, which is provided at one end with the movable contact 10 and is bent at the other end so as to form a bent arm 34. Two movable contact arms 9 are mounted in the movable contact assembly shown, respectively between the

walls

24 and 25 and between the

walls

25 and 26 on the lower frame 19 engaging respective projections 35 formed on both lateral sides of the arm 9 in the

vertical grooves

28, 29, 30 and 31 provided on the lower frame 19. One end'of a compression coil spring 36 rests on the contact arm 9 and the upward projections of the

walls

24, 25 and 26 of the lower frame 19 are fitted in the groove 21 of the upper frame 20 resting on the other end of the coil spring 36. The legs 22 and inward projections 23 of the upper frame 20 are engaged in the respective engaging holes 27 of the lower frame 19, whereby the upper frame 20 is fixed to the lower frame 19 to provide a supporting frame 39 for the movable contacts. 37 are lead wires for the movable contact arms 9.

In the embodiment shown in FIGS. 4A and 4B, the supporting frame 39 is provided in the respective channels of the lower frame 19 with

lateral projections

40 and 41 projecting above the contact arms 9 from the walls, which act as a means for forcibly opening the movable and fixed contact specifically effective at the time when the contacts are accidentally fused together due to discharge sparks occuring between them. The projection 40 is positioned at the side of contact points with respect to the biasing point of the spring 36 and the other projection 41 is positioned at the other side of the spring 36 so as to be adjacent the bent part 34 of the movable contact arm 9.

Operation of the electromagnetic relay according to the present invention will be explained in the followings.

FIG. 2A shows the electromagnet 11 under nonexcited condition and, in this condition, the movable contact arms 9 are supported in their upward position by the boundary edge line, as a fulcrum a, between the bottom 32 and the tapered section 33 of the lower frame 19. Since the movable contact arm 9 is urged downward by the compression of the spring 36 at the right side of the arm in the drawing with respect to the fulcrum a, the side of the contact 10 of the contact arm 9 is urged upward and, thus, the contact 10 is brought into close contact with the normally closed contact 6.

FIG. 2B shows the state in which the electromagnet 11 is under excited condition. The armature 13 is attracted by the core 38 and the contact 10 in contact with the contact 6 is separated from the contact 6. In this state, the movable contact arm 9 is supported by the bent edge line as a fulcrum b of the bent arm 34 of the arm 9 and, since the left side of the movable contact plate 9 is urged downward by the compression of the spring 36, the contact 10 on the same side as the spring 36 on the arm 9 with respect to the fulcrum b turnes into contact with the normally opened contact 7.

Next, the operation of forcible opening of the contacts in the second embodiment having the forcible opening means for fused contacts with reference to FIGS. 4A and 4B.

As described in the foregoing, when the electromagnet 11 is under nonexcited condition, the movable contact 10 of the arm 9 is in contact with the normally closed contact 6 as raised with the point a as the fulcrum in consequent to downward biasing force of the spring 36, as in FIG. 2A. If these

contacts

6 and 10 are fused together due to skarking trouble therebetween, the both contact points will not open due to the fusing, even when the electromagnet 11 is excited and the armature 13 as well as the frame 39 is attracted downwardly as shown in FIG. 4A so that the contactor side of movable contact arm 9 is subjected to downward urge of the spring 36 with the point h as the fulcrum. During the downward movement of the armature and the frame, however, the projection 40 pro vided on the lower frame 19 so as to be above the contact arm 9 will simultaneously be lowered and will abut against the arm 9 so as to push the latter downward, thereby the fused contacts will be forcibly separated to open. Depending on subsequent downward movement of the armature and frame due to the electromagnetic attraction, the thus separated movable contact arm 9 will then be brought into contact with the normally opened contact 7 due to the biasing force of the spring 36 with the point I) as the fulcrum and, thus, the relay will reach the normal excited state as shown in FIG. 28. At the time when, on the other hand, the normally opened fixed contact 7 and thc movable contact 10 are fused together, these contacts will not open even if the electromagnet 11 returns to non-excited state and the armature and the frame are lifted upward due to the tension of the return spring 17. At the next moment, however, the other projection 41 of the frame 19 will abut against the contact arm 9 at the side of the bent section 34 which is lifted at this time with the point a as the fulcrum so as to push said side downward, thereby the

contacts

7 and 10 fused together will be forcibly separated from each other. Depending on subsequent upward movement of the armature and frame as pulled up by the spring 17, the thus opened contact arm 9 will be lifted up with the point a as the fulcrum until it reaches the normally closed fixed contact 6, whereby the relay will be returned to the normal non-excited state of FIG. 2A.

While in the above embodiment the

projections

40 and 41 are disclosed and illustrated in such form that they extend inwardly from the both opposing

walls

24, 25 and 25, 26 and horizontally above the contact arm 9, it will be readily appreciated that in lieu of the above form a pair of projections provided, for example, at lower edges of the respective downward walls of the reverse U-shaped upper frame 20 so as to extend downwardly into the channel in which the contact arm is placed, will perform exactly the same effect.

The present invention is featured in that since the movable contact arm 9 made of conductive rigid material is disposed in the space between the upper frame 20 and the lower frame 19 having the bottom 32 provided with the straight section and the tapered section 33, said contact arm 9 having the movable contact 10 at one end thereof and the bent portion 34 at the other end thereof, and the compression spring 36 urges the movable contact arm 9 downward so as to urge the contact 10 of the movable contact arm 9 into the contact with either one of the fixed contacts, the specific resistance of the contact arm 9 is effectively reduced due to the use of the rigid conductive material which is relatively large in section, as compared with conventional resilient contact arm. This results in that any heat apt to be generated at the arm is reduced and, there fore, comparatively large electric current can be utilized. This means that an electromagnetic relay of a higher capacity can be obtained. Since the contact pressure is determined by the force of the compression spring utilized in combination with the rigid contact arm, the spring constant of this spring can be freely determined and assembly work of the relay is easy.

Another feature resides in that, since the movable contact arm 9 made of rigid conductive material is disposed with the associated coil spring 36 between the upper frame and the lower frame 19 devided into two pieces so as to form the movable contact holding frame 39 it is easy to incorporate the movable contact arm into the frame and also it is possible to simplify the structure of the movable contact arm mechanism of the electromagnet relay.

Further according to the present invention, the relay can perform its relaying operation stably and reliably even when such trouble that the contacts are fused together due to sparkings therebetween is caused to occur, since the holding frame 39 is provided with the

projections

40 and 41 which extend above and in proximity to the movable contact arm 9 respectively at the side of the contact point and the opposite side thereto with respect to the compression spring 36, so that, even when the movable contact is fused to the normally closed contact point or the normally opened contact, the projection 40 at the contact point side of the arm will push down the arm in the instance of the armature attraction due to the excitation of the electromagnet, or the opposite side projection 41 will push down the arm in the event of the armature return due to non-excitation, and thereby the fused-together contacts are forcibly separated and opened from each other.

What is claimed is:

1. An electromagnetic relay comprising the combination of an insulating base, at least one pair of spaced apart fixed contacts mounted on said base, a movable contact member cooperating with said fixed contacts, an armature pivotally mounted for moving said movable contact member back and forth between said fixed contacts, an electromagnetic device for pivoting said armature to move said movable contact member, an insulating holding member carried on said armature for pivoting movement therewith and forming an opening for receiving a portion of said movable contact member, a single compression spring inserted in said holding member for urging said portion of said movable contact member against an opposed surface of said holding member, said opposed surface of said holding member having a first area which forms a first fulcrum for said movable contact member on one side of said spring when said armature is not attracted by said electromagnetic device so that said spring urges said movable contact member toward a first one of said fixed contacts, and a second area which forms a second fulcrum for said movable contact member on the opposite side of said spring when said armature is at tracted by said electromagnetic device so that said spring urges said movable contact member toward a second one of said fixed contacts, said spring being located about centrally between said first and second fulcrums.

2. The electromagnetic relay according to claim 1 which includes spring means for urging said armature away from said electromagnetic device so as to urge said movable contact member toward said first fixed contact when said armature is not attracted by said electromagnetic device.

3. The electromagnetic relay according to claim 1 wherein said movable contact member comprises a plate of rigid and conductive material.

4. The electromagnetic relay according to claim 1 wherein said holding member comprises an upper frame substantially in a U shape in section and a lower frame engaged with said upper frame, said lower frame having upright walls provided with vertical grooves receiving therein lateral projections provided at both sides of the movable contact member.

5. The electromagnetic relay according to claim 3 wherein said holding member comprises an upper frame substantially in a U-shape and a lower frame engaged with said upper frame, said lower frame having upright walls provided with vertical grooves receiving therein lateral projections provided at both sides of the movable contact member.

6. The electromagnetic relay according to claim 1 wherein said holding member is provided with a pair of projections for forcibly opening fused-together contacts said projections being positioned on opposite sides of said compression spring and in alignment with the movable contact member so that the movement of said holding member brings one of said projections into engagement with said contact member in the event of a fusing together of a pair of said contacts.

Claims

1. An electromagnetic relay comprising the combination of an insulating base, at least one pair of spaced apart fixed contacts mounted on said base, a movable contact member cooperating with said fixed contacts, an armature pivotally mounted for moving said movable contact member back and forth between said fixed contacts, an electromagnetic device for pivoting said armature to move said movable contact member, an insulating holding member carried on said armature for pivoting movement therewith and forming an opening for receiving a portion of said movable contact member, a single compression spring inserted in said holding member for urging said portion of said movable contact member against an opposed surface of said holding member, said opposed surface of said holding member having a first area which forms a first fulcrum for said movable contact member on one side of said spring when said armature is not attracted by said electromagnetic device so that said spring urges said movable contact member toward a first one of said fixed contacts, and a second area which forms a second fulcrum for said movable contact member on the opposite side of said spring when said armature is attracted by said electromagnetic device so that said spring urges said movable contact member toward a second one of said fixed contacts, said spring being located about centrally between said first and second fulcrums.