US2844684A

US2844684A - Electrical- contactor

Info

Publication number: US2844684A
Authority: US
Priority date: 1955-01-07
Publication date: 1958-07-22
Anticipated expiration: 1975-07-22
Also published as: BE544224A; GB775269A; FR1145282A

Description

w. w. ANDERSON ET AL 2,844,684

July 22, 1958A ELECTRICALCONTACTOR 2 Sheets-Sheet l FIG.;

Filed Jan. 7, 1955 FIG.2

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July 22, 1958 w. w. ANDERSON ET AL 2,844,634

ELECTRICAL CONTACTOR 2 Sheets-Sheet 2 Filed Jan. 7, 1955 INVENTORS WARREN w. ANDERSON DONALD J. HAMMERAND E A QN l nite States Patent Oiiice y 2,844,684 yPatented July 22, 1958 ELECTRICAL CNTACTOR Application January 7, 1955, Serial No.v 480,504

' 6 cintas. (ci. zoo-a3) The present invention relates to circuit making and breaking apparatus and more particularly to a novel form of contactor assembly which will be found useful in connection with electrical circuits associated with a large variety of equipment, particularly electrical equipment involving a reversible motor circuit or a plurality of individual circuits.

rl'he invention has been illustrated herein in the form of an electromagnetically operated vcontactor assembly having dual pairs of contacts capable of being alternatively opened and closed to alternatively establish or energize a pair of work circuits each containing a suitable load, as for example the field windings of a reversible motor. The invention is however susceptible to modification and, if desired, the contactor may be designed for single or plural working circuit operations.

lt is among the principal objects ofthe present invention to provide a novel contactor assembly of the type briefly outlined above which is quick-releasing with respect to either pair of contacts so that the switching of circuits may take place rapidly, thus avoiding undue arcing at the contact points.

Another vand important object is to provide such a contactor assembly for dual circuit control which requires but a small amount of low voltage current consumption'for its operation. A similar and related object is to provide a dual circuit contactor which will operate to maintain one of the two circuits involved closed indefinitely with no current consumption whatsoever and to maintain the other circuit closed under the influence of a current of low voltage.

Yet another object of the invention is to provide a contactor assembly of this type in which a permanent magnet and an electromagnet may be employed without requiring a reversal of the current through the electromagnet, as is usual in the prior art, to make the permanent magnet effective.

T he provision of a contactor assembly vwhich is rugged and durable and which therefore is possessed of a comparatively long life; one which is comprised of a minimum number of movingparts and which therefore is unlikely to get out of order; one which is extremely compact so that it will occupy `but small space; one which may readily be assembled and disassembled for purposes of inspection, replacement or repair; one which is comprised largely of metal stampings and which may there fore be manufactured at a low cost, and one which otherwise is well adapted to perform the services required of it, are further desirable features that have been borne in mind in the production and development of the present invention.

lnfthe accompanying two sheets of drawings forming a part of this specification, a preferred embodiment of the invention has been shown.

ln these drawings:

Fig. l isa top plan View of a contactor assembly constructed inaccordance with the principles of the invention;

construction.

Fig. 2 is a sectional view taken substantially along the line 2 2 of Fig. 1;

Fig. 3 is a sectional View 'taken substantially along the yline 3`3 of Fig. l;

Fig. 4 is'a `side elevational View of the structure shown in Fig. vl; and

@Fig 5 is a circuit diagram showing the contactor assembly operatively disposed in an exemplary work circuit.

Referring now'to `the drawings in detail, the contactor yassembly involves in its general organization a base plate 410 of a suitable electrical linsulating material, the plate serving as a support forfall of the operative contactor elements. As shown in Fig. 3, "the base plate 10 has mounted thereon at its opposite ends first and

second contact groups

11 and 12 which are preferably of identical A magnetic yoke in the form of a at plate 13 of magnetizable material such as soft iron is positioned in face-to-face contact with the base plate 10 and a plurality of clamping-screws 14 pass through the yoke 13 and are threaded in a laterally turned ange 15 provided on an armature support 16. The armature supporting end of the support l16 is formed ywith a pair of spaced upstanding lugs 17. A -rnagnetizable metallic armature 18 in the 'form of a `rectangular plate is movably positioned to overlap both magnets so as to be within the magnetic intiuence thereof. rl"he said armature is preferably supported medially of its ends on the upper edge of the support 16. The edges yof the armature 18 are "slotted as at 20 (Fig. '3), with the slots registering with 'the lugs 1'7. Retaining pins 21 extend through the lugs 17 to retain the armature in position on the support 16 while permitting slight rocking 'movement of the armature thereon for purposes that will appear presently.

The opposite ends of the `armature have supported thereon rst and

second brushassemblies

22 and 23 respec-tively, including brush elements proper 50, 55 delsigned for cooperation with'the

respective contact groups

11 and 12.

A permanent magnet 25-is composed of extremely hard metal, for example Alnico. armature support 16 and contact group 11 and is secured in position on the lmagnetic yoke '13 by a screw 26 passingfthrough the latter land threaded into a plug or core 27 embedded in the body of the magnet 2S. The core 27 'is composed of softer metal to facilitate the use of the usual equipment for forming the internal threads. An

Iel'ectromagnet Sli/having -a core 31 and a winding 32 `isfcllisposedbetween the armature support 16 and theA contact group 12 and is secured in position on the yoke 16 by a screw 33 ipassing through 'the yoke and threaded into the .core 31. The upper faces of the permanent magnet y25 land core 3'1are substantially at and horizontal and, as a consequence, the armature 18 is of obtuse `Vshaped in'longitudinal cross section in order that, upon rocking movements thereof, the underneath face of the armature may move into face-to-face `magnetic engagementwith these two surfaces alternately `during operation of the contactor assembly.

The

contact groups

11 and 12 being of similar construction, it is thought that a description of one will suice for the other. The contact group 11 is best illustrated in Fig. 2 and comprises a pair of contact elements 34san'd 35, thel latter element being in the form of an L-shaped stamping, preferably of copper which is supported `on yan Lesha'ped bracket 36 kand held in position :bya clamping screw 37. A copper connector strap orbus bar 38 has one'end thereof clamped between the support 36 and contact 35 and Vextends longitudinally of the assembly to a corresponding arrangement of parts including a contact element `40 associated with the contact group v1'2.l A terminal screw and washer assembly It is disposed between the 3 39 are carried medially on the connector strap 38 for connection to a lead-in wire 42. The support 36 is secured on the base by a clamping screw 43.

The contact 34 is generally U-shape and has an inturned foot which is supported on a separator strip 45, a clamping screw 46 serving tohold the various parts in position. The contact 34 carries a terminal screw 47 to which a lead-outwire 48 may be attached.

The brush assembly 22 which is carried at one end of the armature 18 includes a brush proper 50 preferably formed of copper and operable in the manner of a bridging contact to bridge the two

contacts

34 and 35 and complete the otherwise open current path extending from the lead 42 to the lead 48. The brush 50 is slidably carrie-d on a post 51 which is secured by a screw 52 to an ear 53 formed on the end of the armature 18. A head 54 and seating washer 55 limit the downward movement of the brush 50. A spring 56 surrounds the post 51 and normally urges the brush to an advanced position on the post. A guide plate 51a is secured to the armature and slidably engages the brush bar to hold the same from rotational movement about said post 51. As will be explained later, the armature 1S is adapted to be attracted by the permanent magnet 25 so that it will assume the position shown in Fig. 3 wherein the brush 50 engages and bridges the

contacts

34 and 35 and, when in this position, the head and seating washer 54, 54a become extended so that the spring 56 may force the brush 5t) into positive engagement with the

contacts

34 and 35.

The contact group 12, in addition to the contact element 4t?, includes a second contact element 41, the two contacts being mounted in assemblies similar to those shown in connection with the

contacts

34 and 35 and similarly designated in the drawings. Likewise, the brush assembly 23 includes a brush element proper 55 mounted in the assembly 23 in the same manner that the brush 50 is mounted in the assembly 22. The spring 57 of the brush assembly has a slightly greater resistance to compressional forces than has the spring 56 for a purpose that will become clear presently.

As shown in Fig. l, a lead-in binding post 58 and a lead-out binding pest 59 are mounted on the base 1l? on opposite sides of the electromagnet 30 and are electrically connected to the magnet winding 32 by Wires 60 and 61 respectively. The post 58 is adapted to be connected through a preferably, but not necessarily manually operable switch Sw to the positive side of a suitable source of low voltage current as exemplified by the battery B (Figs. 1 and 5). The terminal 59 is adapted to be iconnected to the negative side of the battery B o1 ground.

The contactor assembly is shown in its normal position in Fig. 3 wherein the underneath face of the armature 1d is attracted to the north pole of the permanent magnet 25 and makes contact with the latter so that the spring 56 is under compression. With the parts in the position shown, the brush 50 bridges the

contacts

34 and 35 while the brush 55 is raised from the

contacts

40 and 41. In the exemplary circuit diagram shown in Fig. 5, a work circuit will thus exist from the source S, through lead 70, terminal 41, strap 38, contact 35, brush 50, contact 34, terminal 47, lead 48, load W1 which may be one of the eld coils of a reversible electric motor, diagrammatically shown as a rectangle M in dotted lines, and lead 71 to the negative line.

The other iield winding W2 of the motor M is disposed in a circuit parallel to the circuit just described and, when it is desired to close this latter circuit and open the former circuit, the switch Sw is closed manually to establish a circuit from the positive side of the battery B through lead 72, binding post 58 (Fig. 1), lead 60, winding 32 of the electromagnet 30, lead 61, binding post 59, and leads 73 and 74 to the negative side of the battery. Energization of the electromagnet 30 will attract the armature 18 to the south pole of the magnet core 30 to rock the armature 13 in a clockwise direction as shown in Fig. 3 and cause the brush 55 to bridge the contacts and 41 and establish a circuit through the winding W2 and lead 75 to the negative line. immediately prior to bridging of the contacts 4@ and 41 by the brush 55, the brush will be elevated from the

contacts

34 and 35 to open the circuit through the winding W1.

It is to be particularly noted that with the electromagnet 30 deenergized the attraction of the permanent magnet 25, which is preferably formed of a nickel-ironaluminum alloy known as Alnico #5 and which has a high degree of residual magnetism, is suilicient to maintain the armature 18 attracted against the yielding action of the spring 56 as shown in Fig. 3. Upon energization of the electromagnet 30, a magnetic teld is set up in and around the magnet structure resulting in a flow of magnetic flux which follows generally the path indicated by the full line arrows through the yoke 13, armature support 16, a portion of the armature 18 itself, and the core 31, as well as across the air gap 76 (Fig. 3) existing immediately prior to bridging of the

contacts

40 and 41. This iiow of ilux opposes the residual magnetism of the permanent magnet 25 and bucks the normal ilux ow set up by this latter magnet as shown by the dotted arrows on Fig. 3 so that the effective attractive force of the magnet 25 is materially weakened and the armature 18 is released thereby.

It is also to be noted from an inspection of Fig. 3 that with the magnet 30 deenergized and with the armature 18 elevated above the level of the upper surface of the magnet core 31, the magnet 3d has no effect upon the armature. Since the armature is in intimate contact with the north pole of the permanent magnet 25, a subl stantial portion, if not all, of the armature 18 is magnetized with the strength of the magnetic eld decreasing in proportion to the distance of each increment of the iron material from the pole of the magnet 25. Thus when the magnet 30 becomes energized in such a manner as to render the upper end of the core 31 opposite in polarity to the thus magnetized armature, a very strong magnetic attraction exists between the armature 1S which at the time of its attraction to the magnet 311 has a polarity opposed to the polarity of the adjacent end of the core 31. The phenomena just described is conducive toward a powerful pull on the armature by the magnet 3i) and a consequent rapid shitting of the Various contacts. The pull of the magnet 3) is also assisted by the recoil of spring 56 which is somewhat stronger than the spring 57 and gives an initial impetus to the armature tending to cause it to rock in a clockwise direction with suflicient momentum that the spring 57 will become compressed to a suflicient degree to permit the armature to come within the sphere of magnetic influence of the electromagnet 30. Consequently, the armature 1S may be moved out of the range of influence of the permanent magnet by a minimum exertion of the electromagnet.

When it is desired to restore the original circuit through

contacts

34, 35 to open the contacts 4t), 41, it is merely necessary to open the switch Sw to deenergize the electro magnet 30. The spring 57, having been under compression, will recoil to give an impetus to the armature 18 to rock it in a counter-clockwise direction suiciently to bring it into the range of the magnetic iniuence of the permanent magnet 25.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification except insofar as such limitations appear in the claims. It will be o-bvious that various changes in the details of construction may be resorted to without departing from the spirit of the invention. It will be also understood that the size of the unit and the character of the loads W1 and W2, which are not necessarily the eld windings of a reversible motor bination, a pair of spaced contacts, a permanent magnet having a relatively high degree of residual magnetism, an electromagnet having a iixed core separate from said permanent magnet and in opposite polarity thereto whose polarity is reversed with respect to the polarity of the permanent magnet; means defining a magnetic yoke common lto both magnets including a base plate engaging said permanent magnet and said core, a magnetizable armature positioned to overlap both magnets and having one end engageable with the permanent magnet and its other end engageable with the electromagnet; said armature when in one extreme position being disposed within the magnetic field of the permanent magnet and operative to establish an electrical circuit through said contacts, and an armature support connecting said base and the armature medially of the latter and serving as a common path for the magnetic flux of both magnets, whereby the energization of the electromagnet sets up magnetic flux in said common yoke in opposition to the residual magnetism of said permanent magnet and effects release of said armature for movement thereof out of the magnetic iield of said permanent magnet.

2. An electrical contactor assembly as dened in claim 1 characterized in that said armature support is iixed and is comprised of magnetic material and is in direct contact with said magnetic yoke at one end and is pivoted to said armature medially of the latter at its other end, whereby when the latter is attracted to the permanent magnet a closed flux path exists through the yoke, permanent magnet, armature and support, and whereby when the armature is attracted to the electromagnet a closed ilux path exists through the yoke, armature support, armature and electromagnet core.

3. An electrical contactor assembly comprising in combination, a magnetic yoke, an armature support formed of magnetic material extending medially from said yoke, a permanent magnet having its body extending from said yoke on one side of the support, an electromagnet having a core separate from said permanent magnet and in opposite polarity thereto extending from said yoke on the other side of said support, an armature common to said permanent magnet and electromagnet pivoted medially of its ends to said armature support for limited rocking movement between one extreme position wherein one end thereof is disposed within the magnetic eld of the permanent magnet and another extreme position wherein the other end thereof is disposed within the magnetic eld of the electromagnet when the latter is energized, electrical contact structure at one end of said armature and movable with the latter, said yoke, armature support, armature and core constituting a closed ux path for the electromagnet when the latter is energized, said yoke, armature support, armature and magnet body constituting a closed flux path for the permanent magnet when the armature is attracted thereto, and means for supplying a predetermined current flow to said electromagnet in a direction to set up a ow of ux in said closed path of the electromagnet in opposition to the flow of flux in said closed path of the permanent magnet.

4. An electrical contactor assembly comprising, in combination, a magnetic yoke, an armature support formed of magnetic material extending medially of said yoke, a permanent magnet having its body extending from said yoke on one side of said support, an electromagnet having a core extending from said yoke on the other side of said support, an armature common to said permanent magnet and electromagnet pivoted medially of its ends to said armature support for limited rocking movement between one extreme position wherein one end thereof is disposed within the magnetic field of the permanent mag- ,6 net and another extreme wherein the other end thereof is disposed within the magnetic iield of the electromagnet when the latter is energized, electrical contact structure at one end of said armature and movable with the latter, said yoke, armature support, armature and core constituting a closed iiux path for the electromagnet when the latter is energized, said yoke, armature support, armature and magnet body constituting a closed iux path for the permanent magnet when the armature is attracted thereto, means for applying a predetermined current flow to said electromagnet in a direction to set up a iiow of iiux in said closed path of the electromagnet in opposition to the flow of iiux in said closed path of the permanent magnet, spring means operable when said armature is in said one extreme position to bias the armature away from said extreme position, and spring means likewise operable when the armature is in its other extreme position to bias the armature away from said latter extreme position, said irst mentioned spring means normally exerting a biasing eiiect on said armature less than the attractive force of said permanent magnet and said second spring means normally exerting a biasing effect on said armature less than the attractive force of said electromagnet when said predetermined iiow of current is supplied thereto.

5. In a contactor assembly, a iirst pair of fixed spaced contacts, a second pair of iixed spaced contacts remote from said first pair of contacts, an armature support formed of magnetic material disposed between said pairs of contacts, an armature pivoted to said support medially of its ends `for limited rocking movement thereon, tirst and second brush members mounted on said armature at the opposite ends thereof respectively, said armature being movable between one extreme position wherein said iirst brush member electrically bridges said iirst pair oi contacts and another extreme position wherein said second brush member electrically bridges said second pair of contacts, a permanent magnet positioned between said support and the first pair of contacts and operable upon one end of the armature, an electromagnet positioned between the support and the second pair of contacts and likewise operable upon the other end of the armature, a magnetic yoke bridging the core of the electromagnet, the support, and the body of the permanent magnet and positioned so that when a predetermined ow of unidirectional current is passed through the electromagnet, flux is set up in said yoke in opposition to the residual magnetism of the permanent magnet, a connector strap connecting one contact of the tirst pair of contacts with one contact of the second pair of contacts, and plural spring means operable when said armature is in either of its extreme positions for biasing the same away from said position.

6. In a contactor assembly, the combination set forth in claim 5 wherein the spring means which is operable to bias the armature from the extreme position it assumes when attracted by said electromagnet is of greater force than the other spring means.l

References Cited in the tile of this patent UNITED STATES PATENTS UNITED STATES PATENT QEETCE CERTIFICATE 0F CORRECTUN Patent Noo 2,8..,68n July 22, 1958 Warren W., Anderson et el It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column

3, 2*, for "

leedein wire

4,2," read e@ leedein Wire 7G., me; line 14., for-Head J+2 read m. lead '70 me; column 55 line 9, after "magnet" strike out "and in opposite polarity thereto Signed end sealed this llth day of November 1958,

(SEEE) Attest:

KARL E@ v.M {LNE ROBERT C. WATSON Attesting Ocer Commissioner of Patents UNITED STATES PATENT oEETcE CETIFCATE @F CORREC'HGN Patent No., 2,8A..,68,L July 221 195g Warren W, Anderson et el It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read es corrected below.

Column 3, line 2, for "leed-11 wire 42" read me leedein Wire '70.. de; line 14, forlead' 42 read m, lead '70 ne; column 5,. line 9, after "magnet" strike out nand in opposite polarity thereto" 0 Signed end sealed this 11th dey of November 1958o (SEEE) Attest:

KARL EL, 'AXLINE ROBERT C. WATSON Attesting Ocer Commissioner of Patents