US2359614A - Quick breaking means for electric switches - Google Patents

Description

oct. 3, 1944. w, R BRQQKS 2,359,614

QUICK BREAKING MEANS FOR ELECTRIC SWITCHES Filed March 9 ,E 1942 75m/enig? Mjbur Rif@ @ks @W9/'Mig Patented Oct. 3, 1944 QUICK BREAKING MEANS FOR ELECTRIC SWITCHES Wilbur R. Brooks, Hartford, Conn., assignor, by

mesne assignments, to Federal Electric Products Company, Inc., Newark, N. J., a corporation of New Jersey Application Marcli 9, 1942, Serial No. 433,895

6 Claims.

This invention relates to means for effecting the quick breaking of electric switches. One of the -objects of the invention is to provide means for particularly effecting the quick breaking of electric switches of the magnetic motor starter type.

Another object of the invention is to provide resilient means which may be included in not only newly manufactured switch structures but also existing switch structures to elfect the quick breaking of a switch of the type actuated by a solenoid whereby, upon release of the solenoid, the movable member of the switch is rapidly moved to open circuit position to effect a quick breaking of the switch.

A still further object of the invention is to provide a spring device which is readily adapted for connection with the interlock structure for a. plurality of switches of the magnetic motor starter type whereby a part of the interlockl structure is resiliently urged by said spring to effect rapid movement of the movable element of each switch upon release by its solenoid so that quick breaking of each switch is produced when desired.

Other objects as well as details of the invention will be apparent from a consideration of the following specication and the accompanying draw? The accompanying drawing shows the embodi ment of the invention which is deemed preferable, but it will be understood that the drawing is intended for illustrative purposes only and is not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

In the drawing:

Fig. 1 is a front elevation of a pair of switches and an interlock connected to the switches, the

interlock including springs comprising the presviews of the spring per se detached from the interlock.

In the operation of certain types of machines, it is necessary to use a plurality of electric motors. To properly control the functions of these motors, switches are provided, the switches frequently being of the magnetic motor starter type. Furthermore, it is frequently desirable to operate only one motor at a time and in order to insure that other motors will not be concurrently started, the switches controlling the motors are usually mounted adjacent each other and an interlock structure is connected to the switches to insure the closin-g of only one switch at a time. Where such motors, switches, and interlock arrangements are included in certain types of machines, it is sometimes found desirable to effect a quick breaking of the switches in order that the desired functions of the machine may take place and it is to this latter end that the instant invention relates.

The means comprising the present invention for effecting the quick breaking of electric switches primarily consists of a spring member which is mounted so that one free end is engageable with a pivoted interlock arm of an interlock structure, there being one spring provided for each interlock arm. One end of the interlock arm is connected to the movable armature of one of a plurality of switches and the spring member is so designed that it normally urges the interlock arm in a direction to move the movable armature of the switch connected thereto to open circuit position. A solenoid actuates the armature of each switch and, when energized, holds the armature in closed circuit position. Immediately upon the release of said armature by said solenoid however, the interlock arm connected to said armature, by reason of the spring element, quickly moves the armature to open circuit position and eiects a quick breaking of the switch.

It is to be understood of course that the invention is not to berestricted to use with interlock structures only or to use with the particular interlock structure described herewith since the invention obviously may be applied to a single switch and the actuating arm therefor. Other applications of use are also conceivable and the present illustration and description are primarily for purposes of showing only the preferred embodiment of the invention.

In order that the invention might be fully understood, not only is a description of the spring elements and the manner of their co-action with the moving parts of the interlock structure given but the operation of the interlock with respect to the plurality of switches engaged thereby is also set forth. No claim is made to the interlock'structure per se and its association with the switches in vthis application since the same forms the subject matter of a separate patent application, Serial No. 430,739, iiled Feb-- ruary 13, 1942.

Referring to the drawing, each individual magnetic motor starter switch I8 has a thermal re lay control unit I2, all of which are mounted on a suitable base plate I4. The respective motor starter switches are provided with a movable contact carrier I6 actuated by an armature I8 movably mounted in the lower portion of the electro-magnetic member 28 which electro-magnetic member serves to actuate the armature I8I to move the contact carrier I6 into engagement with the stationary contact blocks 2|.

Each armature is provided with a depending plate 22 which, preferably, is a lamina of the laminae which comprise the armature I8 in conformity with customary construction of such armatures. As clearly shown in Fig. l, the plate 22 projects below the lower ends of the associated laminae forming the armature I8 suiciently to afford ample space in which to place an elongated aperture or slot 24 for purposes to be eX- plained. It will be understood that the armature I8 and movable contact carrier I6 to which the armature is connected are mounted for vertical movement with reference to Fig. 1 and such movement is guided by suitable means incorporated in the magnetic motor starter switch structure. Said guiding means, however, does not form a part of the instant invention and therefore is not illustrated.

The mechanical interlock is generally designated 26. The details of the mechanical interlock comprise a supporting member in the form ofV a mounting bracket 28'which, as viewed in Fig. 4, has downward extending supporting legs 30A having outward extending plates 32 each provided withy an aperture 34 by which the mounting bracket may be suitably-'secured to the base plate I4' such as by a pair of 'screws36L A pair ofl switch engaging interlock arms 38- are pivotally mounted to the mounting bracket; 28Y by suitable pivot Studs 4I] each of which pivot studsV is accommodated in a suitabley bearing aperture disposed in each interlock arm 38inter mediate the ends thereof. A washer 39 may be placed on the pivot studs between each interlock arm and the mounting bracket tofacilitate` movement of the interlock arms.

The innermostend of eachinterlock arm 38 is shaped to `form a cam surface 42 angularly dis posed to the longitudinal axis of the interlock:

arm 38. Said end of the interlock arm is also formed with a slightly curved end surface 44 which is substantially a segment of a circle having a radius extending from the pivot stud 40. The curved end surface 44 may be considered a continuation of the cam surface 42 and both surfaces in eiTect form a composite or continuous cam surface, the curved end surface 44 being in the nature of a dwell on the composite cam surface.

The outer end of each interlock arm 38 is provided with an armature engaging member 46 which is offset upward. The armature engaging member 46 is accommodated in the slot 24 provided in the depending plate 22'on each arma ture. The dimensions of each slot 24 are such that they provide free movement therein of the respective armature engaging members 46 without binding in order that the armature may be raised and lowered during actuation thereof by the electro-magnet member 2-0, and during which raising and lowering the outer end of the interlock arm engaged in the slot 24 will be moved therewith.

An interlocking pin bracket or front guide plate 48 having oiset mounting ears 50 disposed at either side is secured to the front face of mountingA bracket 28, as viewed in Fig. 1, by screws 52 which extend through suitable apertures in the oiset mounting ears 58 and also elongated apertures or slots (not shown) in the mounting bracket 28 and are threaded into locking means hereinafter described. As clearly shown in Fig. 4, the offset between the front guide plate and the mounting ears 58 provides a space between the front guide plate and the mounting bracket 28 to accommodate the inner ends of the interlock arms 38.

The front guide plate 48 is provided medially thereof and adjacent the uppermost edge with a guide slot 56, which guide slot is best shown in Fig. 1 and is for a purpose to be described.

Mounted on the rear or underside of the mounting bracket 28 is an interlock pin guide plate 58 which may be termed the rear guide plate, the same being secured to the mounting bracket by the screws 52 which are threadably received in apertures 6D formed in said rear guide plate to not only secure the guide plate 58 but also lock the front guide plate 48 in operative position. Medially disposed in the rear guide plate adjacent its upper edge, as viewed in Figs. 1-3, is a guide slot 62' which is substantially identical to the slot 55, the slots 56 and 62 being so arranged in the respective guide plates that when said guide plates are assembled as shown in Figs. 1-4, said slots are substantially co-extensive, parallel, and superposed over each other. Said guide slots are held in alignment with each other as just described by the pair of screws 52 which are threaded into the apertures 60 in the rear guide plate 58. loosened, the front and rear guide plates may be moved within certain limits as a unit with respect to the mounting bracket 28 by reason of the slots 54 in said mounting bracket.

A locking means illustrated in the form of a cylindrical interlock or locking pin 6'4 is disposed in a generally rectangular aperture 61 in the mounting bracket 28. The locking pin is provided at opposite ends with cylindrical trunnions 66 which are disposed in the guide slots 56 and 62 of the front and rear guide plates to rotatably mount the locking pin 64 between said guide plates. Obviously the locking pin may not only rotate with respect to the guide plates but the same may also move longitudinally with respect to the same within the limits of theslots 56 and 62. The dimensions of aperture 61 are such that at no time during the movement of the locking pin in any direction will the periphery Vthereme engage the'periphery of the aperture 6'I.

The locking pin is primarily for the purpose of engaging the angularly disposed cam surface 42 provided on the end. of each interlock arm to prevent the inner end of said arm from moving downward' and correspondingly prevent the armature engaging member 46 on the outer end of the interlock arm from moving upward whereby the movable contact carrier is also prevented When said screws are suitablyv from moving into engagement with the stationary contact block on one of the magnetic motor starter switches. This function is clearly illustrated in Figs. 1 and 2. The locking pin 64 is held in engagement with the cam surface 42 of one interlock arm by the end surface 44 of the other interlock arm, as is also clearly illustrated in Figs. l and 2. The'last mentioned interlock arm is held with the end surface 44 against the locking pin by the depending plate 2 2 on the closed magnetic motor starter switch which holds the outer end of said interlock arm in uppermost position.

With one magnetic motor starter switch thus closed, the second one may not be closed. After said closed switch has been opened however, the armature will drop to its lower position, simultaneously moving the outer, raised'end of the engaged interlock arm downward. move the inner end of the engaged interlock arm upward and remove the end surface 44 from abutting engagement with the locking pin B4 as viewed in either Figs. l or 2, following which, the locking pin 64 may move from locking engagement with the cam surface 42 ofthe other interlock arm, particularly when the second switch is closed by energizing its electro-magnet to move the armature of said switch upward, which armature simultaneously carries therewith the outer end of the interlock arm 38 engaged therewith and moves the innerend of said arm downward during which movement the cam surface 42 on said arm will force the locking pin 64 toward the inner end of the other interlock arm and into engagement with the cam surface 42 of said other interlock arm to lock its inner end against movement downward and prevent the closing of the switch with which said second interlock arm is engaged.

Assuming both magnetic motor starter switches are open, the interlock arms will then'be substantially disposed in the position illustrated in Fig. 3. This position may be termed the neutral position. It will be readily seen that, from this neutral position, the outer end of either one of the interlock arms may be raised by the closing of the switch associated therewith, which action will lower the inner end of the actuated interlock arm and simultaneously force the locking pin away from the outer end of the interlock arm that is actuated and farther into engagement with the cam surface 42 on the inner end of the other interlock arm to hold or lock said inner end of said other interlock arm against downward movement. The end surface 44 of the first interlock arm will, as explained in the foregoing, hold the locking pin B4 in such locking engagement with the inner end of the second interlock arm. From the neutral position, both switches may not be simultaneously closed since the cam surface of both interlock arms would be caused to engage the locking pin.

The locking pin 64 is preferably rotatably mounted to provide anti-friction engagement between it and the cam and end surfaces 42 and 44 of each of the interlock arms 38.

It will be appreciated that in the mass production of mechanisms by methods used in modern industry, manufacturing variations will exist and items such as magnetic motor starter switches will not always be exact duplicates of each other in that the spacing of certain elements in said switches with respect to certain other elements is not always the same.

This WillY For example, it has been found in connection with the development of the present invention that when two magnetic motor starter switches are mounted ona common base plate I4 and both switches are either open or closed, the disposition of the de-` pending plates 22 and the slots 24 therein will not always be the same with respect to a com.- mon means on the base plate such as the bottom edge.

To compensate for the above mentioned differences in spacing of the various elements of said magnetic motor starter switches, certain members of the interlock structure comprising the present invention have been made adjustable to permit proper alignment ofthe armature engaging members 45 with the respective slots 24 through which said armature engaging members project. Such adjustment is afforded by the slots 54 in the mounting bracket 28, which slots permit the vertical movement of the front and rear guide plates 48 and 58. Movement of these guide plates is correspondingly imparted to the locking pin 84 which, in turn, will vary the, points of contact upon engagement of said locking pin with the inner ends of the interlock arms 38. After the position of the locking pin has been properly adjusted by so moving the guide plates 'and the proper position located, said proper position of said guide plates is maintained by tightening the screws 52 into the plate 58. The

'proper position is such, for example, that when both switches are open, the interlock arms 38 may assume a neutral position similar to that shown in Fig. 3. Similarly, the .proper position willalso permit one interlock arm to maintain the locking pin in proper locked lengagement with the other interlock arm or vice versa to absolutely' prevent the closing of one of said switches when the other of said switches is already closed.

The present construction also includes further means for maintaining the proper adjustment of the locking pin with respect to the inner ends of the interlock arms comprising a pair of selftapping screws 68 which pass through suitable openings in the offset mounting ears 50 on the front guide plate 48. Before inserting said selftapping screws 68, the mounting bracket 28 is drilled to provide holes therein, using said openings in the oiset mounting ears 50 as a templet, following whichthe self-tapping screws 68 may be threaded into said drilled holes to assist the screws 52 in securing the locking plates in proper position.

The switches illustrated in the foregoing are moved to open position by the force of gravity alone.v It is the purpose of the instant invention to provide means whereby said switches may be opened considerably more quickly than the opening by gravity affords whereby a quicker breaking of the switches is obtained.

The structure which comprises the essence of the present invention, namely, the resilient means which urges each of the pivoted interlock arms 38 in a direction to rapidly move the armature I8 connected therewith in a downward direction, is herein illustrated as a substantially U-shaped spring 10. In the preferred embodiment of the present invention, one spring is provided for each interlock arm 38. It is to be understood, of course, that the invention is not necessarily to be so restricted however in that it is conceivable a single spring may be anchored to the structure and ybe provided with a pair of free ends which are .respectively engageable with ,the interlock arms 38 to urge each of said arms in the desired direction.

As best shown in Figs. 1 through 3, and 6; each spring 1U is formed with` one free end l2'bent out- Ward' to be received in. the space between the guide' plates 48 and 58 which also accommodate the ends of the interlock arms having the cams: thereon. the spring .bearing against the uppen edge ofthe offset. portion of the front guide plate 48 to serve as a stop means for one endl'ol` the spring. Each spring 18 extends from the ofsetl portion in the front guide plate around the pivot stud 4U andy is then bent back upon itself to ex.- tend toward the cam end of the interlock arm it: is to engage. The other free end of the spring 101 terminates in a .substantially U-shaped` hooky 14;, the plane of the hook extending at right' angles to the plane in which the remaining porstion of the spring is disposed. The U-shaped hook 14 engages the under side of the interlock arm: 28 with which it coacts adjacent the innermost end whereby the spring normally urges the inner end of the interlock arm upward and thearrnature engaging member 46 on the outer end' f downward whereby the armature with which the member 46 is engaged is constantly urged in a. downward direction.

It will thus be' seen that immediately upon the release of an armature by the solenoid associatedA therewith, the spring 10 through the medium of.

the interlock arm 38 will rapidly move the armature to open` circuit position to effect a quick breakin-g of the switch.

Not only do the springs 'I0 eiect a quick breaking of the switches but, upon the solenoid of a closed switch becoming de-energized, the spring engaging the interlock arm associated withsaid switch quickly raises the inner end of said interlock arm from engagement with the interlock pin 64 whereby, should' it be desired to immediately close the second switch upon the opening of the rst, the interlock arm associated with the secondl switch can quickly cam the interlock pinlill from out of locking engagement with its inner end. without having to first wait for gravity acting on the armature on the rst switch to movethe first interlock arm from engagement with the interlock pin. In other words, the springs '10.` also serve to quickly clear one or the other inner ends of the interlock arms from locking engagement with the interlock pin and in this way a quicker closing of the second switch maybe eiected fnllowing the openingv of the rst switch.

Ample space is provided for the spring '10;r be-y tween each interlock arm 38 and the mounting' bracket 28 by reason of the washers 39 which are mounted on each pivot studv 40 between the in'- terlock arm and the mountingbracket. In its.` position of repose, the spring 10 has its outer free ends suniciently spaced from eachother that when said spring is inserted in operative position between the upper edge of the front guide platev 48 and the under side of the' interlock arm 3B, the tension produced in the springwillV be suf.- cient to rapidly urge the armature engaging member 46- of each interlock arm, to its lowermost position in' which the switch associated therewith will be in open circuit position. This tension is alsov suiicient to. retain the spring', 10: in operative; position; the outward bent end 12l engaging behind the: offset portion of the: front. guide plate 48 to retain the spring; against;Y move'- m'ent out-ward or endwise, awayy fromv the pivot studiv 4l) and the latter prevents; appreciable Verticalf movementy of: thefbight of the spring,

It. will be. apparent. that'the spring 104 may. be readily connected to,y the' interlock structure in a -number ofdifferent ways, one of whichV consists in4 temporarily dismounting the interlock assembl'y from` the: base plate Hl following which' the inner end. of each interlock arm may be elevated to permit the U-shapedr hook12 on one end ofsaid springlll` tobe engaged under the lower edge ofl the interlock arm. The bight of the U-shaped spring 18 is then, disposed about, the pivot stud 40'- and.` theoutwardr bent free endv 12 is snappedv into operativeposition in the space between the guide plates 48. and 58'. With the lowering,- of the innerend of the interlock arm intoneutral'position such as shown in Fig. 3, the springv 10 will ber placed undertensiomin which condition it will remain atv all times while the interlock is connected. to the switches and the base plate.

The rapidity with which the spring 'I0 moves the interlock arm38 is determined by the strength ofV the spring. If more rapid movement and consequent quicker opening of the switch is desired,

a, stronger spring will be used. Adequate space for varioussized springs is provided by the presentwashers 39 used to space the interlock arms with respect to the mounting bracket 28. If a t heavier spring is requiredr than can at present be accommodated, a thicker washer 39 may be used to provideadditional space.

It will thus be seen that the springs IIJ may be readily attached not only to newly manufactured interlocks. but, by the method of insertion de scribed above, the springs may also be expeditiously incorporated in previously manufactured interlock structures of the type described and i1- lustrated as well as any other structures wherein.z the spring is adaptable.

With the instant invention, thel applicant has provided. a simple but effective mechanism for electing aquick break in a switch, and particularly in one of the magnetic motor starter type. The spring means which comprise the essential feature ofthe instant invention are quickly attachable to interlock structures used in conjunctionwith a plurality of switches of the magnetic motor starter type and the inclusion of such springs in the interlock structure necessitates no modification er change ofthe structure of either the interlock or the switches in any way.

While the invention has. been illustrated anddescribedE in its preferred.Y embodiment and has included certain details, it should be understood that the invention is not to be limited to the precise details hereink illustrated and described since thes same may be carried out in other Ways, falling within thev scope of the invention as. claimed.

What I claim. is:

11. Thel combination of an, electric switch of the; magnetic motor starter type having a solenoid actuated movable electric contact carryingy member... abase, an arm pivoted to-said base and adjacent; one end being operatively connected to said movable electric contact carrying member, and a spring having one portion anchored with respect to said base and another portion coacting 5 wi-thlsaid: pivoted arm to normallyurge the same a; direction to move the movable electric contact carrying member to open circuit position whereby upon release by said solenoid said movable electric contact-carrying member is quickly rnc-ved by said spring-urged pivoted arm to effect aquick breaking of the switch.

2., The.4 combination of an electric switch of the magnetic motor starter type having a sole` noid actuated movable electric contact carrying member, a base, an arm pivoted to said base and adjacent one end being operatively connected to said movable electric contact carrying member, and a substantially U-shaped spring extending about the pivot of said arm, said spring having one end portion anchored with respect to said base and the other end portion coacting with said pivoted arm to normally urge the same in a direction to move the movable electric contact carrying member to open circuit position whereby upon release by said solenoid said movable electric contact carrying member is quickly moved by said spring-urged pivoted arm to effect a quick breaking of the switch.

3. The combination of a plurality of electric switches of the magnetic motor starter type each including a solenoid actuated movable electric contact carrying member, an interlock adapted to maintain one switch open while the other is closed, said interlock having a base mounted in xed relationship with respect to said switches and including a plurality of pivotally mounted arms each of which operatively engages one of said solenoid actuated movable electric contact carrying members, and spring means anchored with respect to said interlock base and having movable portions respectively engaging each pivotally mounted arm to normally bias each arm in a direction to urge each movable electric contact carrying member to open circuit position, whereby upon release by the solenoid said movable electric contact carrying member is quickly moved by its respective spring-urged pivotally mounted arm to open circuit position to effect a quick breaking ot the switch.

4. The combination of a plurality of electric switches of the magnetic motor starter type each including a solenoid actuated movable electric contact carrying member, an interlock adapted to maintain one switch open while the other is closed, said interlock having a base mounted in fixed relationship with respect to said switches and including a plurality of pivotally mounted arms each of which operatively engages one of said solenoid actuated movable electric contact carrying members, and a plurality of springs each having one portion anchored with respect to said interlock base and another portion engaging one of said pivotally mounted arms to normally urge the same in a direction to move the movable electric contact carrying member engaged therewith to open circuit position, whereby upon release by the solenoid said movable electric contact carrying member is quickly moved by the spring-urged pivotally mounted arm engaged therewith to open circuit position to effect a quick breaking of the switch.

5. The combination of a plurality of electric switches of the magnetic motor starter type each including a solenoid actuated movable electric contact carrying member, an interlock adapted to maintain one switch open while the other is closed, said interlock having a base mounted in iixed relationship with respect to said switches and including a plurality of pivotally mounted armseach of which operatively engages one of said solenoid actuated movable electric contact carrying members, and a plurality of substantially U-shaped springs each anchored at one end with respect to said interlock'l base and engaging one pivotally mounted arm with its other end, said springs each also extending about the pivot of the interlock arm engaged thereby and normally urging said pivotally mounted arm in a direction to move the movable electric contact carrying member engaged therewith to open circuit position, whereby upon release by the solenoid said movable electric contact carrying member is quickly moved by the spring-urged pivotally mounted arm engaged therewith to open circuit position to effect a quick breaking of the switch.

6. The combination of a plurality of electric switches of the magnetic motor starter type each including a solenoid actuated movable armature which carries electric contact members, an interlock adapted to maintain one switch open while the other is closed, said interlock having a base mounted in fixed relationship with respect to said switches and including a plurality of pivotally mounted arms each of Which operatively engages one of said armatures and also including locking means mounted for movement by one of said pivotally mounted arms to one of a plurality of positions wherein it is held by engagement with said one of said pivotally mounted arms to lock the other pivotally mounted arm and movable armature engaged thereby against movement in one direction when the other movable armature is in closed circuit position, and spring means anchored with respect to said interlock base and having movable portions respectively engaging each pivotally mounted arm to, normally bias each arm in a direction to urge each movable armature to open circuit position, whereby upon release of the armature by its solenoid said pivotally mounted arm holding said locking means in said one position is quickly moved from engagement with said locking means to permit said other pivotally mounted arm to move said locking means from locking engagement therewith when it is desired to close the switch to which said second arm is connected.

WILBUR R. BROOKS.

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