US3723925A

US3723925A - Electromagnetic relay

Info

Publication number: US3723925A
Application number: US00257586A
Authority: US
Inventors: R Alten
Original assignee: Essex International Inc
Current assignee: Lear Corp EEDS and Interiors
Priority date: 1972-05-30
Filing date: 1972-05-30
Publication date: 1973-03-27
Anticipated expiration: 1990-03-27

Abstract

An electromagnetic relay comprises an energizable and deenergizable magnetically associated relay coil within which is mounted a pair of magnetic, electrically isolated, core parts connected in a relay controlled circuit, a terminal mounted on one core part and connected in the controlled circuit, and an armature mounted at one end on the other core part and carrying an electrical contact at its other end which is movable into engagement with the terminal to provide a current path between the armature and the terminal in response to the energization of the coil. The armature also is movable into and out of engagement with the one core part to provide between the armature and terminal a second current path parallel with the first current path to minimize heating.

Description

United States Patent 91 Alten [54] ELECTROMAGNETIC RELAY [75] Inventor: Ralph W. Alten, East Detroit, Mich.

[73] Assignee: Essex International Inc., Fort Wayne, Ind.

[22.] Filed: May 30, 1972 [21] Appl. No.: 257,586

[52] U.S. Cl. ..335/l87, 335/196, 335/203,

. 335/281 [51] Int. Cl. ..ll0lh 45/00 [58] Field ofSearch ..335/l87,l85,203,202,196, 335/128,281,276

[56] References Cited UNITED STATES PATENTS 1 Mar. 27, 1973 Primary Examinerl-larold Broome Attorney-John F. Learman et al.

[57] ABSTRACT An electromagnetic relay comprises an energizable and deenergizable magnetically associated relay coil within which is mounted a pair of magnetic, electrically isolated, core parts connected in a relay controlled circuit, a terminal mounted on one core part and connected in the controlled circuit, and an armature mounted at one end on the other core part and carrying an electrical contact at its other end which is movable into engagement with the terminal to provide a current path between the armature and the terminal in response to the energization of the coil. The armature also is movable into and out of engagement with the one core part to provide between the armature and terminal a second current path parallel with the first current path to minimize heating.

12 Claims, 6 Drawing Figures nlllll 2e 5 [f If FI'GI I FIG.2

PATENTEDHARZY 1915 FIG.6

FIGS

ELECTROMAGNETIC RELAY- This invention relates to'an electromagnetic relay and more particularly to an electromagnetic relay having high current carrying capacity and low heat loss characteristics.

The prior art contains many examples of low cost relays consisting primarily of stampings riveted to each other and to phenolic or other resinous bases. Such relays have objectionable characteristics especially when subjected to high ambient temperatures and to heat generated by high current values. It is not uncommon, for example, for temperatures under the hood of an automobile to reach 300 F. Some resinous materials will undergo a curing reaction at such temperature, thereby frequently rendering the relay mounted thereon inoperative. Due to the different expansion rates of metal stampings, rivets, and phenolic resin terminal blocks, the dimensional changes of the various parts differ and the parts frequently become loose causing alignment problems. In addition, when the parts are loosened portions of the relay controlled circuit, which normally are in electrical contact, spread to increase the electrical resistance of the circuit and correspondingly reduce the maximum current carrying capacity of the relay. The increased resistance causes increased heat which further decreases the current carrying capacity of the relay. The confronting surfaces of relay contacts conventionally are covered with a noble metal such as silver to improve their make and break characteristics. In relays having a high current carrying capacity the contacts must be relatively large. If the relatively expensive noble metal covers the entire surfaces of the contacts, the cost of the relay becomes excessive. It has been found that a relay can perform adequately if the noble metal is provided only on those portions of the contacts between which arcing occurs, provided that another circuit is provided in parallel with the contacts to share the current load after the contacts have closed.

An object of this invention is to provide a low cost electromagnetic relay which has the capability of carrying high currents at high temperatures.

Another object of the invention is to provide a low cost electromagnetic relay which is relatively free from misalignment and dimensional change problems associated with temperature variations.

A further object of the invention is to provide a low cost electromagnetic relay which utilizes a portion of a movable armature and a core to provide a current path in parallel circuit relation with relay contacts that are moved into and out of engagement in response to changes in a magnetic field.

The relay disclosed herein includes terminals which are connected in a relay controlled circuit, mount the relay to a terminal block, and are fixed to a pair of elec trically insulated magnetic core members which, in addition to conducting the magnetic flux field, comprise part of the relay controlled circuit. The magnetic core members are disposed in part within a coil-supporting bobbin having an integral divider strip for electrically isolating the core members from each other. This construction minimizes the core material used within the coil bobbin.

Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a front elevational, partly sectional view of an electromagnetic relay constructed according to the present invention and supported on a mounting block;

FIG. 2 is a top plan view;

FIG. 3 is a bottom plan view;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1 and illustrating the relation between the coil supporting bobbin and the magnetic core parts disposed therein;

FIG. 5 is an enlarged, sectional view taken along the line 55 of FIG. 4; and

FIG. 6 is a sectional view taken along the line 66 of FIG. 1.

A relay constructed according to the invention is designated generally by the reference character 10 and is adapted to be mounted on a terminal block 12 which may comprise phenolic resin or other suitable electrically insulating material. The relay 10 includes a pair of spaced apart, confronting

terminals

14 and 16 having end portions 14a and 160 which pass through apertures 18 in the terminal block 12. The terminal ends 14a and 16a are adapted to be connected in a circuit (not shown) to be controlled. The

terminals

14 and 16 are identical except that the terminal 14 is slightly longer and includes a laterally bent contact supporting arm or flange 19 for a purpose later to be described. As is best illustrated in FIG. 6, each of the

terminals

14 and 16 includes shoulders 21 and locking tabs 23 abutting the top and bottom, respectively, of the block 12 to secure the terminals to the block. A third terminal 20 is carried by the block 12 and is similar in construction to the

terminals

14 and 16.

Between the

terminals

14 and 16 is a bobbin 24 formed of insulating material and having a central passage 25 extending therethrough. Received in the passage 25, in side-by-side relation, is a pair of

magnetic core members

26 and 27 having

upstanding legs

28 and 29, respectively, spot welded or otherwise suitably secured to the

terminals

14 and 16. The

core members

26 and 27 are isolated from one another by a partition 25a of insulating material and forming an integral part of the bobbin.

The upstanding leg 28 of the core part 26 includes a flange 30 which overlies the bobbin to serve as a pole piece for a purpose to be described hereinafter. The upstanding leg 29 of the core part 27 includes a flange 31 parallel to the flange 30 to serve as a pole piece for a purpose presently to be described.

Riveted as at 32 to the core flange 31 is an armature assembly 33 comprising an electrically conductive metal leaf spring 34 to which is riveted as at 35 an L- shaped magnetic armature member 36 terminating at one end in a shorter limb 37 generally parallel to the upstanding core leg 29, but spaced therefrom by an air gap g. The longer limb of the armature 36 overlies the pole piece 30 and normally is spaced therefrom by a gap 0. The leaf spring 34 extends beyond the opposite end of the armature member 36 and mounts a contact 38 thereon for movement toward and away from a fixed contact 39 supported on the flange 19 of the terminal 14. The

contacts

38 and 39 normally are disengaged and portions of their confronting surfaces preferably are'coated with a noble metal such as silver to enhance their conductivity and to minimize the deleterious effects of arcing. The leaf spring 34 hingedly mounts the armature 36 on the core part 31 for swinging movement of its longer limb into engagement with the pole piece 30. As the armature member 36 swings toward the core part 30, the gap 3 decreases to reduce the reluctance of the magnetic circuit and thus provide an improved pull in characteristic.

Wound around the bobbin 24 so as to encircle the

core parts

26 and 27 is a coil 40 of magnet wire. One

end 41 of the coil is connected to the terminal 20 and the other end 42 of the coil is connected to a terminal 43 mounted on the block 12. The terminal 20 is the input terminal and is adapted for connection to one pole of a battery or other source of electrical potential. The terminal 43 carries a spring metal arm 44 adapted to engage a metal cover (not shown) by means of which the terminal 43 is grounded. The terminal 43 could be connected to theother pole of the battery.

To condition the relay for operation the

terminals

14 and 16 are connected in a circuit to be controlled by the relay and the

terminals

20 and 43 are connected to a source of electrical potential to energize the coil 40, whereupon a magnetic flux path is established through the core part 27, the leg 29, the pole piece 31, the air gap g, the armature leg 37, the armature 36, the air gap a, the pole piece 30, the leg 28, and the core part 26. The magnetic armature 36 thus is magnetically attracted'to the pole piece 30 and will swing downwardly as permitted by the hinge spring 34 toward a position in which the armature 36 engages the pole piece 30. When the armature 36 engages the pole piece 30, the

gap a is eliminated and the gap g is reduced to minimize the reluctance of the circuit and enhance the pull-in characteristics of the relay.

As the armature member 36 moves toward, but before it engages, the pole piece 30, the

contacts

38 and 39 will engage to establish a current path from the input terminal 16 through the core leg 29, the spring 34, the

contacts

38, 39, and the output terminal 14 to complete the relay controlled circuit and provide the operating or control function. Shortly after the contacts 38 and 39-close, the magnetic armature 36 will engage the pole piece 30 to provide a current path in parallel with the current path through the

contacts

38 and 39 to reduce the resistance of the circuit and thereby minimize the heating effects which would otherwise occur. Since the current path initially is established only through the

contacts

38 and 39, however, any arcing which may occur upon completion of the circuit is confined to those contacts.

When the current to the control coil 40 is interrupted, the armature 36 is released from the pole piece 30 and is separated therefrom by the return force of the spring 34. The

contacts

38 and 39 remain in engagement until after the armature 36 has'separated from the pole piece 30 so that whatever arcing occurs upon breaking of the circuit again is confined to the contacts 38and 39. Since the make and break arcing is confined to the

contacts

38 and 39, the pole piece 30 and the armature 36 remain substantially clean and unaffected by arcing. v

The disclosed relay construction substantially eliminates alignment problems in assembling the parts of the relay inasmuch as the

legs

26 and 27 of the magnetic core first are'inserted into the bobbin 24 and the entire relay is assembled prior to the

terminals

14 and 16 being inserted through the apertures 18 in the mounting block 12. The function of the mounting block 12 thus is to support and maintain the parts of the relay l0 assembled.

The disclosed embodiment is representative of a presently preferred embodiment of the invention,b ut is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.

I claim:

1. An electromagnetic relay comprising magnetic core means terminating at opposite ends in pole pieces; an electrically energizable and deenergizable coil encircling said core means between said pole pieces; means for connecting and disconnecting said coil to and from a source of electrical potential; first and second terminals adapted for connection in a relay controlled circuit; magnetic armature means; means mounting said armature means on one of said pole pieces and for movements into and out of engagement with the other pole piece in response to energization and deenergization of said coil; contact means connected to one of said terminals and carried by said armature means for engagement with the other of said terminals in response to movement of said armature means toward said other pole piece to provide a first current path between said first and second terminals; and means connecting said other pole piece to said other terminal to. provide a second current path between said first and second terminals when said armature means engages said other pole piece.

2. A relay according to claim 1 wherein movement of said armature means toward engagement with said other pole piece effects engagement of said contact means with said other terminal prior to engagement of said armature means with said other pole piece.

3. A relay according to claim 1 wherein said first terminal is connected to said one of said pole pieces.

4. A relay according to claim 1 wherein said core means comprises a pair of magnetic members in sideby-side relation within said coil.

5. A relay according to claim 4 including insulating means interposed between said pair of members.

6. An electromagnetic relay comprising a bobbin formed of insulating material and having a passage therethrough; an energizable and deenergizable coil of magnet wire wound on said bobbin; means for connecting and disconnecting said coil to and from a source of electrical potential; a pair of magnetic core members toward and away from theother of said legs in response to electrical energization and deenergization of said coil; contact means movable into and out of engage ment in response to movement of said armature toward and away from said other of said legs; first and second terminal means adapted for connection in a circuit c'ontrolled by the engagement and disengagement of said contact means; means connecting said terminal means to said legs; and means supporting said terminal means,

whereby said coremembers are maintained in said passage and said bobbin is maintained between said legs. I

7. A relay according to claim 6 wherein said armature comprises an L-shaped member having its shorter limb adjacent but spaced from said one of said legs, and having its longer limb overlying and spaced from the other of said legs when said coil is deenergized.

8; A relay according to claim 7 wherein said armature is mounted by saidhinge means in such position that said longer limb engages said other of said legs and the space between said shorter limb and said one of said legs is reduced when said coil is energized.

9. A relay according to claim 8 wherein said armature is mounted by said hinge means in such position that said longer limb engages said other of said legs following engagement of said contact means.

10. A relay according to claim 6 wherein said hinge means comprises a spring strip of electrically conductive material, one end of said strip extending beyond one end of said armature and being secured to said one of said legs and the other end of said strip extending beyond the other end of said armature and overlying one of said terminal means.

11. A relay according to claim 10 wherein said contact means comprises a first electrically conductive member secured to said other end of said strip and a second electrically conductive member secured to said one of said terminal means.

12. A relay according to claim 6 including insulating means interposed between said core members.

Claims

1. An electromagnetic relay comprising magnetic core means terminating at opposite ends in pole pieces; an electrically energizable and deenergizable coil encircling said core means between said pole pieces; means for connecting and disconnecting said coil to and from a source of electrical potential; first and second terminals adapted for connection in a relay controlled circuit; magnetic armature means; means mounting said armature means on one of said pole pieces and for movements into and out of engagement with the other pole piece in response to energization and deenergization of said coil; contact means connected to one of said terminals and carried by said armature means for engagement with the other of said terminals in response to movement of said armature means toward said other pole piece to provide a first current path between said first and second terminals; and means connecting said other pole piece to said other terminal to provide a second current path between said first and second terminals when said armature means engages said other pole piece.

4. A relay according to claim 1 wherein said core means comprises a pair of magnetic members in side-by-side relation within said coil.

6. An electromagnetic relay comprising a bobbin formed of insulating material and having a passage therethrough; an energizable and deenergizable coil of magnet wire wound on said bobbin; means for connecting and disconnecting said coil to and from a source of electrical potential; a pair of magnetic core members occupying said passage in side-by-side relation, each of said members having an upstanding leg one of which is located at one end of said bobbin and the other of which is located at the other end of said bobbin; a magnetic armature; hinge means mounting said armature on one of said legs for movement of said armature toward and away from the other of said legs in response to electrical energization and deenergization of said coil; contact means movable into and out of engagement in response to movement of said armature toward and away from said other of said legs; first and second terminal means adapted for connection in a circuit controlled by the engagement and disengagement of said contact means; means connecting said terminal means to said legs; and means supporting said terminal means, whereby said core members are maintained in said passage and said bobbin is maintained between said legs.

8. A relay according to claim 7 wherein said armature is mounted by said hinge means in such position that said longer limb engages said other of said legs and the space between said shorter limb and said one of said legs is reduced when said coil is energized.