US2375216A - Electric switch - Google Patents

Description

J. EATON ELECTRIC SWITCH May 8, 1945.

Filed June 5, 1943 Inventor: John Eaton,

Patented MayS, 1945 ELECTRIC SWITCH` y I John Eaton, Schenectady, N. Y., assigner to General Electric Company, a corporation of `New York Application .Tune 5, 1943, Serial No. 489,730

8 Claims.

My invention relates to electric switches, more particularly to electromagnetically operated switches or contactors, and has for its object a 4contacter provided with simple and eecti-ve means for producing a wiping action between the contacts, so as to increase the current carrying capacity of the device.

In `carrying out my invention in onev form, l `.provide two springs for holding the movable contact in position on a support moved by an operating coi1, Vthese two springs applying their forces at diii'erent points on the movable contact. The movable and stationary contact surfaces are arranged angularly so that the movable contact rst touches the stationary contact at one edge thereby to elect yielding oi one of the springs and a normal rolling and wiping action on the stationary contact, after which theiinal movement oi the armature to its attracted position eiects further yieldingof the first spring and also yielding of the second spring to obtain an increased contact pressure.

f Preferably, the spring first to yield is relatively woah as odmpared with a second spring, the Y magnetic pull applied to the armature at that time'of initial contact not being strong enough to :nove the annature against the torce applied hy the second spring. Moreover the second spring applies to its forceA at an edge ci the movable contact .opposite the point oi initial contact engagement so as to-provide the manirnum leverage -to-loreak any weld between the two contacts at the initial point of engagement.

More 'specifically I provide a relatively weak helical spring which applies a force at substantially the center of the movable Contact,

which spring yields iirst, and a relatively strong flat spring which engages an outer edge of the movable contact remote from the initial point oiengagelnnt between' the two contacts.

For a more complete understanding oi my invention, reference should be had to the accompanying drawing, Fig. -1 of which-is a plan view partly in `section of an electric switch embody- -ing my invention; Fig. Eis a view mainly in section taken alongthe line 2--2 of Fig. l lool:- ing in the direction of'y the arrows; Fig. Bris a `sectional View taken along the line '3-3 of Fig. i

looking in the direction of the arrows; Fig 4 is a plan view of the armature and movable contact mechanism; Fig. 5 is asectional view or" Fig. 4 looking in the direction of the arrowsi while Fig'. 6 ls afrontelevation view ol Figa showing one o! the springs. Referring to the drawing, I have shown. my'

' magnet thearm|8.\ Y 1 It. will be noted that the springstrlp 2|' is prol invention in one form as comprising an operating coil I0 'provided with a central magnet iron core member Il, end core pieces I2 and I3, anda iron armature I4 having one end pivoted at I5 on the end core member I3. The armature I4 is biased to its unattracted position by means of a. helical tension spring I1. l

Secured to the armature I4 is a rigid switch arm I6'. Ihis switch arm has one end secured to the armature by means of rivets I9, the switch larm and the rivet being electrically insulated from the armature by layers of insulation i8 and' I8a and a cylindrical insulator 20 surrounding the rivet. The switch arm extends at right angles to the direction of movement of the armature, as shown, at right angles to the pivot axis of the armature.'

Also secured to the armature is a relatively strong spring strip 2l which has one end extending between the arm i6 and the layer of insulation It and secured to the armature by the rivets i9. This spring extends along the switch arm but is bent away from the switch arm at an angle,`andits end has a' portion 22 bent at right angles toward the switch' arm toa position in closely spaced relation with the side of the switch.

arm at its end.

The switch arm carries a bridging contact member 23 made of electrically conducting niaterial provided with contacts 24 and til at its ends for; engagementwith stationary contacts it and il. At its outer edge, i. e. the edge opposite the pivot of the armature, the bridging contact 'has' an extension 2B provided with a V shaped groove 2&3 which forms an elongated bearing seat for portions 3B and 3l on the e'nd of the vspring strip 2l. It will be observed that portions 39 and 3i are spaced apart to form in elect an elongated hearing in the end of the spring 2l. i G the bridging contact is provided with two projections' 32 andv 33. These protections are spaced along thelength of the contact arm in tween which and the adjacent side of the bridging` contact is a vrelatively weak helical com-4 .pression spring Bl. The pin 35 extends through an aperture Aprovided .for it' in the arm I6 and vis held in place by a pin 38`extending through .its end and lying in a groove provided I orv it in Also, on its side adjacent the arm vided with an enlarged opening through which extends the spring i1 and the pin 36, this opening defining two bent arms 39 and 40 which are connected togetherat their outer ends by the cross bar 4l.

The bridging contact member is put in place, the pin 33 being removed, by forcing its outer edge portion between the arm I6 and the spring 2|, the outer end of the spring 2| yielding somewhat thereby to seat the portions 30 and 3| on the end of the springlin the bearing groove 29. It will be observed that the spring 2| also by its engagement with the bearing 28 holds the bridging contact member 23 in transverse relation with the switch arm. The projections 32 and p 33 hold the bridging contact in spaced relation with the arm. At this time the force applied by the spring 2| to th bearing seatr 29 is sufiicient to. tilt the opposite side of the bridging contact away from the arm i6 about the pro.- jection 33`as a pivot. Next the pin 3G and' spring 31 are put in place and the pressure of the spring 31 forces the inner edge of the bridging member oracle t tact, i. e., to the bearing seat 2Q, provides the greatest possible leverage for the force of this spring in breaking a weld between the two contacts at their inner edges where engagement is iirst made, in the eventthat a weld is formed.

about the projection 33 as a pivot toward vthe arm i6 until the projection 32 4rests onthe arm.

As seen in Figs. 2 and 3, the stationary contacts 26 and 21have their contact surfaces disposed at a predetermined acute angle with the contact faces on the bridging member. Consequently, when the coil isenergized and the armature moves the contact arm toward closed circuit position, the inner edges of the movable contacts, i. e., the edges adjacent the pivot of the armature, engage the stationary contacts rst. Thereupomas the armature moves toward its attracted position, the spring 31 yields to allow the bridging contact to pivot at its outer edge on the contact arm about the projection 33 in a clockwise direction as seen in Fig. 2. Also the movable contacts at the same time pivot clockwise on the stationary contacts, producing a rolling and wiping action until the contact faces are in parallel contact made engaging relation. The armature still is not quite in its fully attracted position and, in continuing its movement to the final attracted position, it moves the arm i5 away :from the bridging member, which is now in. engagement with the stationary contacts, thereby further compressing the spring 31 and bending the Stringer spring 2| In other words, the arm I6 moves away from the outer end of the spring 2| which yields. Thus the bridging contact member ismaintained in engagement with the stationary contacts by the combined forces applied by the springs 2| and 31.

It will be observed that the bearing portions and 3| on the spring 2| are on opposite sidesof the end of the switch arm and are spaced a substantial distance apart thereby to apply positive pressures to each of the bridging contacts 2l the'helical spring 31.

lIt will be observed that the helical spring 31 applies its force at substantially the center of the bridging contact and, therefore, has only half the leverage with respect to the inner edge of the bridging contact, as compared with the iiat spring 2|. Moreover, of course,"the force applied by the helical spring ls preferably much less than that applied by the hat spring 2i. Thus, in the event of a weld at the initial point of engagement, the breaking of a weld and roll of the bridging contacts over the stationary contacts is assured by the stronger spring 2 The various parts of the switch are supported on two parallel rectangular plates 42 and d3 made of electrically insulating material, such as a phenolic condensation product, each plate consisting of two layers, the inner layer being somewhat smaller than" the outer layer and forming a Asupport for a iiexible strip covering member M,

preferably made of a brous insulating material. which with the two -side plates encloses the operating parts of the device.`

These -two side plates are -held in fixed relation v 'with projections 53 and 54 which extend through slots in the side plates. vSimilar projections and 56 areA provided on the core member I3, which projections extend through apertures in the side members. Also, the apertures for the projections 55 and 56 are enlarged to receive the projections 51 and 58 on-the armature thereby to hold the armature in place with its lower edge, as seen in Fig. 2', pivoted on the left-hand end of the core One advantage of the arrangement of the two springs so that the force of one only is applied when the contacts first engage is that the force applied to the armature follows roughly the maximum pull applied' to the armature during its movement. It will be understood that, as the armvdzure moves toward its attracted position. the

In other words, the armature would not be actuated if it member I3.

i A stop cross bar 59 extending between the plates and secured to the plates by smaller end portions extending through openings in the plates is vprovided for the armature Il when in its unattracd position, as shown in Fig.' 2. A short bolt I0 extends toward the left, as seen in Fig. 2, from the center of vthis bar 53 and extends loosely through holes provided for it in the overlapping vends of the strip M and an outer cross bar 6|.

Thev outer cross bar E I is provided to secure the outer overlapping end of the flexible ilbre strip 44, the end of the strip being secured to the cross-barby means of rivets 6|a, only one of which is shown. A nut 62 on the bolt 60 holds across bar 5|- in place. Another cross bar 32o is' secured to the inner overlapping end of the strip 44 by means of rivets. 'This cross bar 32a is similar in construction to the cross bar 6|, and likewise has small ends mounted in slots in the outer edges of the side members 42 and I3.

Terminals 33 and 64 secured tothe side plates are provided for the ends I0. Also, similar of the operating coil While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I there- v terminals 65 and 66 are prof kvided for the stationary contacts. As shown in Fig. 3, the two stationary contacts are mountedfore contemplate by the appended claims to cover any such modiiications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

v1r. A switch comprising a switch member, means for moving said switch member between open and closed circuit positions, a movable contact movably mounted on said switch member,

a rst spring 'applying a force to said movable Contact therebyto bias said movable contact against said switch member, a stationary contactarranged to be engaged by said movablecontact when said switch member is moved toward said closed circuit position, said stationary contact having its contact surface at anangle with the contact surface of said movable contact so that edges of said contacts iirst engage each other and said spring yields to provide a prev; liminary rolling action of said movable contact on said stationary contact, and a second spring applying a force to the opposite edge of said movable contact to hold said, opposite edge againstsaid switch member during said rolling action and yielding to apply an increased contact, maintaining force during a predetermined i'lnalA movement of said switch member to its closed circuit position.

2. A switch comprising a pivoted switch arm, a movable contact movably mounted on the mov- .able other end of said switch arm. a rst spring applying' a force to said movable contact at sub'- stantially its center thereby to bias said movable contact against said switch arm,v a stationary contact arranged to be engaged by said movable contact when said switch arm is moved in one direction, said stationary contact having its contact surface at an angle with the contact surface of said, movable contact so that inner edges of said contacts adjacent the pivot` of said switch arm rst engage each other and said spring yields to provide a preliminary rolling action of said movable contact about its inner edge on said stationary contact and about its outer edge on said -contact arm to a :final contact made position,

and a second spring on said switch arm applying a force to said outer edge of said movable contact to hold said outer edge against said arm during said 'rolling action and yielding to apply an increased contact maintaining force duringa predetermined final movement of said switch arm. if

3. A' switchcomprising a'switch arm, a movable contact mountedon the movable other end of said switch arm, a rst spring biasing said movable contact against said switch arm. a bearingseat on an outer edge of said movable contact, a second spring secured to said arm at one i end and having its other end seated in said bearing seat, and a stationary contactJ arranged to be engaged b'y said movable contact having its contact surface atan angle with the contact surface of saidmovable contactso that any edge oi' the said movable contact surface opposite said helical spring,

`.switch arm, an elongated bearing seat on one edge of said bridgingcontact, a second spring secured to said switch arm at one end and having its other end transversely elongated and seated in said bearing seat to hold said bridging contact in transverse relation withv said switch arm and apply a force to said one edge of said bridging contact -in the same direction as the force applied by said first spring but greater than the force applied by said rst spring, and stationary contacts arranged to be engagedby said bridging contact, said stationary contacts having their contact surfaces at an angle with the contact surfaces on said bridging contact so that upon movement of said switch arm in one direction edges ci the latter contact surfaces opposite said one edge engage said stationary contacts first thereby to provide a rolling action and compression of said iirst spring and then compression oi said second spring upon continued movement oi said switch arm.

5. a switch comprising a rigid switch arm, a pin secured to the movable end oi said switch arm extending at right angles with said switch arm and in the direction of movement of said movable end. a movable contact on said movable end provided with a central aperture through which said pin extends, a helical compression spring on said pin biasing said movable contact against said 4switch arm, a bearing seat on one edge of said movable contact, a second spring having one other end seated in said bearing seat to apply a force to said movable contact in the same direction as said helical spring, said second spring applying c. greater forcethan said and a stationary contact arranged to be engaged byy said movable Contact when said coil is energized, said stationary contact having its contact surface at an angle with the contact surface on ,said movable contact so thatupon movement of said. switch arm in one direction an edge of the latter opposite said one edge ,en-

gages said stationary contact drst to provide a rolling action and compression oi said helical spring and then yielding of said second spring upon continued movement of said'switch ami.

6. A switch comprising a' switch a dat rst spring having one end secured tosaid switch' arm audits other end extending laterally atsubtion with said movable end, a contact membermounted on the movable end of said arm, a bearing seat for the end'of said giirst spring on the outer edge of said contact member whereby said first ,spring biases said outer ejdge toward said arm, a second spring bearing on. said contact member thereby to force said contact member about said rst spacing member to a predetermined spaced relation with said arm, a third spring for biasing said' switch arm to a predetermined circuit position, a stationary contact having a. contact surface at an angle witha' contact surface on said contact member so that upon movement of said switch arm in one direction the i ner edges of said surfaces engage each other rst thereby causing pivotal movement of said contact member on said arm against the force applied by said second spring into parallel engaging relation with said stationary contact, and said 'contact arm being arranged to move away from said contact member during the final movement of said switch arm in said direction so that said movable contact member is held against said stationary contact member by the forces applied of said switch arm to a position in closely spaced relation with said movable end, a Contact member mounted on the movable end of said arm,

a pair of spacing members between said Contact member and said arm spaced apart along the length of said arm, a bearing seat for the end' of said first spring on the outer edge of said contact member whereby said first spring biases said outer edge toward said arm with the outermost of said spacing members in engagement with said arm, a second spring bearing on said contact member thereby to force said Contact member about said rst spacing member to a predetermined spaced relation with said arm determined by said second spacing member; a third spring for biasing said switch arm to a predetermined circuit position, a stationary Contact having a contact surface. at a predetermined angle with a contact surface on saidcontact member so that upon movement of said switch arm to another position the inner vedges of said surfaces engage each other iirst thereby causing pivotal movement of said contact member on said iirst spacing projection against the force applied by said second spring into parallel engaging relation with said stationary Contact, and said switch arm being arranged to move away from said contact member during the iinal movement of said switch arm to said other position so that said movable contact member is held against said stationary contact member by the forces applied by said iirst and second springs.

8. A switch comprising a switch arm, a first spring having one end secured to said switch arm and extending along said switch arm with its other end extending laterally at substantially right angles with the end of said switch arm to a position in closely spaced relation with the end of said switch arm, a bridging contact member mounted on said end of said arm extending crosswise thereof, a pair of projections on said bridging member at substantially its'v middle spaced apart along the length of said arm, a bearing seat for the end of said iirst spring on the outer edge of said bridging contact whereby said first spring biases said outer edge toward said arm with the outermost oi said projections in engageinent with said arm, a second spring bearing on said bridging member thereby to force the other of said projections into engagement with said switch arm against the force applied by said first spring, a third spring for biasing said armature to its unattracted position and said switch arm to its open circuit position, spaced stationary contacts in position 'to be engaged by opposite ends of said bridging member when said switch arm' is moved in one direction toward a closed circuit position, said stationary contact surfaces being positioned at an angle with the contact surfaces on said bridging member so that the inner edges oi said surfaces engage each other .first thereby causing pivotal movement of said bridging member on said outer projection against the force applied by said sec-y ond spring for at engagement of said contact surfaces, and said stationary contacts being positioned to provide for movement of said switch arm away from said bridging member against the forces applied by said first and second springs when said switch arm moves -to its final closed circuit position. JOHN EATON.

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