US2233926A - Electric switch - Google Patents

Description

March 4, 1941. A. G. srmis. l-1v .ELECTRIC SWITCH Original Filed Dec.

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Patented Mar. 4, 1941 UNITED STATES ELECTRIC SWITCH Allen G. Stimson, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Griginal application December 1, 1938, Serial No. 243,376. Divided and this application April 25,

1940, Serial No. 331,662

6 Claims.

My invention relates to electric switches, more particularly to relays and the like, and has for its object the provision of an improved device of this character which is simple and reliable and has a long operating life.

This application is a division of my ,copending application, Serial Number 243,376, iiled December 1, 1938, for a magnetically operated des vice.

In carrying out my invention, I provide a resiliently mounted movable contact carriage operable between upper and lower xed contacts and adapted to provide a wiping engagement of the movable contacts with either of the fixed contacts. l

For a more complete understanding of all the features of my invention, reference should he had to the accompanying drawing in which Fig. l is a plan view oi a magnetically operated relay embodying my invention; Fig. 2 is a left side elevational view of Fig. l; Fig. 3 is a sectional view taken along the line fil- 3 of Fig. l looking in the direction of the arrows; Fig. 4 is an inverted sectional view taken along the line fi-i 'c of Fig. l looking in the direction of the arrows;

Fig. 5 is an inverted sectional view taken along the line 5--5 of Fig. l looking in the direction of the arrows; Fig' is an exploded view of some or the parts of the relay shown in perspective.

Referring to the drawing, i have shown my invention in one form as applied to a magneti`= cally operated relay. rlhe relay includes a base oi suitable insulating material upon which the 'various Aparts are mounted and secured. The bottom tace il of the base Il), best shown as the upper edge of the inverted sectional view ol the relay in Fig. 4, is provided with a groove l2 extending longitudinally therei into which one leg of an L-shaped magnetizable frame I3 is secured by means of the hollow rivets or eyeletsl The. holiow rivets i4 and I5 themselves constitute suit-1 able bolt holes inthe base I0 into which bolts may. be inserted for fastening the relay to a panel or the like. The other leg of the L-shaped magnetizable frame I3 extends upwardly along one side of the base I0, as seen in Fig. 3 projecting a short distance above the portion of the base.A A portion of the b ase I0 is moulded with an opening across which extends the frame I3, as shown in Fig. 5, whereby a well or recess is formed into which a core member I6 and its energizing winding I1 are disposed. IThe core member I6 consists essentially of a series of l'aminations of magnetizable material fastened together (Cl. ZOU- 164) by means of the rivets I6a to form an elongated pole piece or core member of substantially rectangular cross-section. The vertically disposed core member I6, whtich extends upwardly from the bottom of the base I0 in the Well provided therefor, is surrounded by a number of turns of fine wire constituting an energizing coil I1 provided at its sides with the terminals I8, the core member I6 forming a support for the winding I1 and separated therefrom by a sleeve of insulating material I9 which surrounds the core member.

As shown in Fig. 6, the core I6 has its lower end positioned in a recess struck into an auxilary frame plate 2| which is fastened to the core member I6 by a screw 22 threaded longitudinally into the bottom of the core member. A pair of extensions or ears 23 are provided on the auxiliary frame plate 2l having the holes 2t therein adapted to receive the screws 25 which are threaded into the frame iii to secure the auxiliary frame plate 2l thereto. As shown, 'i have provided a sheet of insulating material 2E,

such as paper, between the auxiliary frame plate il andthe main trame i3 toy increase the reluctance ot the magnetic cir-cuit including these` two members. On the auxiliary frame plate 2l opposite the extension 23, I have 'provided a iur'- ther extension or nib 21 which registers with a recess or slot in the hase lll and engages a wall thereof for holding the auxiliary plate 2l in posi1 tion on the-base.

With the auxiliary frame plate 2l and fastening means I have provided, the core member It, the energizing winding i1, and the auxiliary frame plate 2i maybe easily assembled and disassembled irom the base I0 and main frame i3 as a unitary structure when the relay is mounted on a panel. Thus, one is enabled to make Yreplacements in the field, particularly of the r ing by means of a screw driver, are also disposed in the holes 2l in the auxiliary frame plate 2l in a manner so that they willnot fall out while these parts are being assembled or disassembled. At their lower ends the screws 25 are provided with a. threaded portion 23 and at their upper ends nearest the head of the screw with an under cut portion 23 of reduced diameter. By providing internal threads in the holes 24, the lower threaded portion 23 of the screws 25 must be first threaded through .the holes 24. After that, the under cut portion 23 of the screws 25 is loose- 1y disposed in the holes 24 so that the screws 25 may be threaded into screw holes in the frame i3 to fasten the auxiliary frame plate 2l to ,the frame. Because of the internal threads in the holes 24, the screws 25 are noteasily removable froxn the plate 2i without first aligning the threads for screw engagement and, therefore, are not likely to fall out of the auxiliary frame plate during assembly or coil replacement.

To provide a more uniform pull and increased quiet torque characteristics in the alternatingcurrent' magnet, I have provided a pole shading construction comprising a pair of parallel slots 30 and 3| in the upper end of the core member I8 whichdivide the cross-sectional area of the upper end of the core member into three distinct areas, which taken together comprise a single pole face 32 on the core. One of the three extending `portions of the core member I6 comprising the pole face 32 is encircled by a shunted pole shader winding 33 which may be formed of two short-circuited turns of copper wire or punched copper plates to provide a low resistance shader. The middle extension on the core member is encircled by a larger shunted pole shader winding 34 which also surrounds the shaded extension encircled by the pole shader 33 and may comprise a single short-circuited turn of copper wire of substantially greater resistance value than the winding 33. The third extension on the core member i6 having no pole shader thereabout constitutes the un-f shaded portion of the pole face 32. The pole shaders 33 and 34 are secured in the grooves 30 and 3| respectively by swaging the copper in these grooves. As shown in Fig. 3, it will be noted that the upper surfaces of the pole shaders 33 and 34 are on substantially the same plane, the slot 3| being only made deep enough -for this purpose, and no deeper, to avoid undue weakening of the core member I 6 at this point.

The cooperating individual shader windings 33 and 34, when properly proportioned, are well adapted to change the flux characteristics of the core member I6 to provide a more uniform pull and greater quiet torque than can be obtained with a single shader winding. The three phase flux components provided thereby, when acting together, have a greater minimum intensity than the usual two phase ilux. The intensity of this minimum value of flux is a determinant of quiet torque characteristics; the higher the minimum iiux value during each cycle, the less is the likelihood of the attracted armature to overcome the attracting forces and chatter. A more uniform pull on the armature ispbtained since Ithe difference between the maximum and minimum values of flux during each cycle is lessened. -By encircling the lshader winding 34 about both of the shaded portions of the pole face 32, the

middle portion of the pole face 4is shaded, and at the' same time, the other shaded portion oi' the pole face which is surrounded by its own shader winding 33 is, in effect, doubly shaded. A three phase flux is provided which has a. component at the unshaded portion of the pole face which follows closely the variations in energization current in the coil I1. The middle portion of the pole face 32 has a flux component which lags the energization current by an electrical angle of less than and the iiux at the doubly shaded portion lags the energization current to a greater extent than the middle portion, but less than 90 electrical degrees. Relative lag is determined by relative amount of shading provided by the shading windings 33 and 34.

Referring now to Fig. 3, the top of the upwardly extending leg of the frame i3 .is provided with a fulcrum edge 36 on which an armature 35 is mounted for pivotal movement. .At either side of the fulcrum vedge 35 on the frame i3 is a projection 31 cooperating with a short projecting portion 38 of the armature 35 which extends across the fulcrum edge 35 and rests thereon. The projecting portion 38 of the armature 35 is disposed between the projections 31 on the frame which prevent any substantial lateral displace- .ment of the armature 35 on the fulcrum edge 36. The upper ends of the extensions 31 on the frame I3 extend laterally inwardly over the projecting portion 38 of the armature 35 in an overhanging relation thereto for preventing any substantial upward movement of the armature 35 off of the fulcrum 36. The projecting portion 33 of the armature 35 is notched at either side to form the shoulders 39 which cooperate with the extensions 31 on the frame i 3 to prevent any substantial longitudinal movement of the armature 35 on the fulcrum 36 in one direction. Secured to the upper surface of the armature 35 is a spring strip 40 extending longitudinally thereof having a bent end portion 4| adiacent the fulcrum edge 36 which cooperates with the frame i3 to prevent any substantial longitudinal movement of the armature 35 on the fulcrum 3B in the other direction. In other words, thearmature 35 is positioned on the fulcrum edge 36 and is prevented from moving more than a very limited amount longitudinally and laterally thereon by reason of the cooperating spring 4i), the extensions 31 on the frame, and the shoulders 39 on the armature. By raising the end 4i, the spring 4I] is deflected upward and removal of the armature 35 from the frame is permitted.

The main body of the armature 35 extends laterally above the core member i8 and is pivotally movable about the iulcrum 3E adjacent the pole face 32 upon energization of the coil i1. The opposite end of the spring strip 43 from that nearest the fulcrum 35 extends beyond the end of the amature 35 and is resiliently supported by spring means whichnormally bias the armature to its unattracted position as weil as provide a connection with contact operating means operable by the movement of the armature between its attracted and unattracted positions. The support and contact operating means includes a guide member or post 42 which may be formed by a metal 'strip staked at its lower end into the frame I3. The upper end of the guide post 42 contains a slot 43 running longitudinally thereof into which one prong of a trifurcated end portion 40a of the spring strip 40 is disposed for movement up and down ln the slot 43. On the metal guide post 42, I have slidably mounted a contact carriage 44 of insulating material, the carriage 44 having a central aper- -ilp all

spring 45 serving to support the carriage 44 and resting on the insulating liner 26 of the frame I3. The spring 46 is interposed between the upper side of the carriage 44 and the end 40a of the spring 46 to provide a resilient connection for transmitting .the downward movement of the armature to the carriage.

For adjusting the disposition of the armature 35 with respect to the free position of the spring 46, I have provided the spacing washers 41 between spring strip and the upper end of the helical spring 46. The spacing washers 41 are provided with an aperture 46 for receiving the guide post 42 and have a pair of diametrically opposed inwardly extending portions 49 projecting into the groove 43 on the guide post 42. The ends of the projections 49 are'spaced apart slightly less than the thickness of the end of the guide post 42 which' forms the top wall of the slot 43.4 These washers may be made of any resilient material, preferably in the form of thin metal punchings which may be pushed overthe end of the guide post 42 in the number desired and which will be retained in place thereon by the projections'45 disposing themselves in the slot 43. Because of the projections 49, the spacing Washers are unable to fall off of the guide post 42 but may be easily assembled on and removed from the post, the projections 49 being forced apart slightly `for this purpose in the course of assembly or removal.

Secured to the base I0 are the terminals 50a, Sla, 52a, and 53a each connected to one of the fixed contacts 5U, 5i, 52, and 53. The fixed contacts 50, 5I and 52, 53 comprise spaced apartpairs of contacts which cooperate with the movable contacts 54 and 55 respectively disposed therebetween for engagement with the upper set 5l and 453, when the armature 35 is in the unattracted position, and for engagement with the lower set of contacts 56 and 52 when the armature is in the attracted position. Extending at opposite sides of the contact carriage 44 are a pair of arms 55 and 5'1 on which the movable contacts are mounted, the arms being displaced off the center line of guide post 42 or offset for providing a leverage means on said contact carriage 44 whereby the carriage is given a tilting or pivotal movement as the contacts are engaged and disengaged. The contact carriage 44 is slidable on the guide post 42, as hereinbefore mentioned, and-it is also arranged for limited pivotal movement about the guide post 52 so that the movable contacts 54 and 55 are given a wiping or rolling action upon engage ment and disengagement with the respective fixed contacts.

The effectiveness and uniformity of this wiping action is enhanced by providing the pairs of pivot points 58 and 59 on the contact carriage 44 upon which the springs 45 and 46, respectively, are seated. The center lines of the pivot points are on the same vertical plane and are disposed adjacent the narrow edges of the guide post 42. The fixed contacts are also disposed on a common vertical plane which is parallel to the plane of the pivot points. In this manner, as the carriage 44 is slidably moved up and down along the guide post 42, a definite moment arm is provided for tilting the carriage 44 as the contacts engage and dlsengage. This definite moment arm for the tilting of the contact car-` riage 44 provides a substantially uniform wiping and rolling engagement of the contacts desirable for avoiding and breaking pin point welds back to its unattracted position.

on the contact surfaces, scrubbing dustv and foreign matter therefrom and providing good engagement of the contacts.

Connecting the movable contacts 54 and 55 in -circuit'with a pair of terminals 60 provided therefor secured to the base l0 are the resilient conductors 6I which are adapted to iiex in accordance with the movement of the contact carriage. 'I'he conductors 6l are of substantially U-shaped configuration having outwardly bent ends at the point of connection with the terminals 60 and movable contacts I54 and 55. To minimize the life shortening effects of fatigue to which the conductors 6| are subjected during frequent operation of the relay over long periods by reducing the deiiectionand hence the stress at the points of support, I have provided the strengthening members 62 and 63 at these outwardly bent end portions of the conductors 6I. The strengtheners 62 and 63 comprise strips of metal or other flexible material tted along the inner curvature of the bends of the conductors 6| which assist in distributing the bending stress at these points over a wide area and greatly assist in prolonging the life of the conductors 6|.

In operation of the relay, the armature 35 is normally supported freely by the springs and 46 in the unattracted position above the pole face 32 of the core member I6. The movable contacts 54 and 55 are maintained in engagement with the upper fixed contacts 5i and 53 for making the circuit including the terminals 5la, the contacts 5i and 54, a conductor 6I and a terminal 60, and the circuit including the terminal 53a, the contacts 53 and 55, a con= ductor 6I, and a terminal 60. When the winding il is energized, the armature 35 is attracted downwardly to the core i6 and the force of its movement is transmitted to the contact carriage i4 by the helical spring t5. The downward movement of the contact carriage d4 disengages the lpreviously engaged contacts 5i and 54 also 53 and 55. Upon suilicient downward travel, the contacts and 54 and also 52 and 55 start to engage, the contact carriage 44 being in substanu tially upright or vertical alignment with the vertical axis of the guide post t2 on which it slides. As the' contacts engage, further downward movement of the contact carriage 44 brings into play the leverage action of the arms and 51 thereon which cause the carriage torock or tilt on the conveniently placed pivot points 53 and 55 of the carriage upon which the springs 45 and 46 are bearing. This rocking action wipes the movable contacts 54 and 55 across the liixedA contacts 5i) and 52 in a desirable manner and good engagement of these contacts is provided. Two further circuits are then completed and each includes one of the lower fixed contacts 50 and 52 instead of the upper fixed contacts 5l and 53 as before. The wiping engagement of the contacts 5l and 54 also 53 and 55 occurs in an identical manner when the armature 35 moves Moreover, in each instance as the contacts disengage, some wiping action is effected between those contacts.

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 therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

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

1. In a switching devicehaving a movable 01)- erating member, the combination of a guide post having a slot therein which is closed at one end of said post, said member movable in said slot during movement of said member, a contact carn riage movably mounted on said guide post, a spring providing a resilient connection between said contact carriage and said member, and a spacing washer on said guide post interposedl between said spring 'and said member, said washer having a pair of inwardly extending portions projecting into said slot whose ends are spaced apart slightly less than the thickness o! said guide post to secure said washer on said guide post. said closed end of said guide post serving to limit the movement of said member.

2. In a switching device having a movable operating member, the combination comprising switching means operable by said member including a guide post having a slot therein which is closed at the top, an extension on said member slidable in said slot during movement of said member, a contact carriage slidably movable on said guide post, a spring encircling said guide post providing a resilient connection between said contact carriage and said member, and a spacing washer interposed between the end of said spring and said extension on said member, said washer having a portion encircling said guide post and a pair of diametrically opposed inwardly extending portions projecting into said slot on said guide post whose endsare spaced apart slightly less than the thickness of the top of said guide post to prevent said washer from falling off of said guide post when the switching device is assembled, said Vclosed top of said guide post further serving to limit the movement in said slot of said extension on said member.

3. In a switching device having a movable operating member, the combination of switching means including a guide post, a contact carriage slidable on said guide post, a spring encircling said guide post interposed between said operating member and said carriage for transmitting the movement of said operating member thereto, pivot means on said carriage including a plurality of projections on which said spring is seated enabling limited pivotal movement of said carriage thereon, a fixed contact, and a cooperating movable contact secured to said carriage and oirset from said projections to afford a leverage means for providing a wiping and rolling en gagement of said contacts by the pivotal movement of said carriage upon engagement of said contacts. e

4. In a switching device having a movable operating member, the combination of switching means including a guide post immovably ypositioned, a contact carriage slidable on said guide post, a spring encircling said guide post below saidV carriage providing a resilient support there for, a second spring encircling said guide post above said carriage interposed between said operating member and said carriage for transmitting the movement oi' said operating member thereto, pivot means on said carriage including a plurality o! projections on which said springs are seated enabling limited pivotal movement of said carriage thereon, a fixed contact, and a cooperating movable contact secured to said carriage and oiset from said projections to afford a leverage means having a definite moment arm from the center line of said projections for providing ay wiping and rolling engagement of said contacts by the pivotal movement oi' said caririage from said position oi axial alignment about said pivot projections upon engagement of said contacts.

5. In a switching device having a :movable operating member mounted on a base, the combination comprising switching means operable by said memberincluding a guide post secured to said base, a contact carriage slidable on said guide post, a helical spring encircling said guide post below said carriage fior resiliently supporting said carriage, a second helical spring encircling said guide post above said carriage interposed between said carriage and said member for resiliently connecting said elements, said carriage having depressions for receiving and seating said springs, a pair of pivot projections on 5 from said position o! axial alignment upon engagement of said movable contact with either of said xed contacts for providing a wiping action between said contacts.

6. In a switching device having a movable operating member, the combination comprising switching means operable by said member including a guide post having a slot therein `which is closed at the top, an extension on said member slidable in said slot during movement of said member. a contact carriage slidable on said guide post and arranged for pivotal movement to a limited extent, spring means encircling said guide post above and below said contact carriage tor resiliently supporting said carriage thereon, a fixed contact, a cooperating movable contact secured on said contact carriage and offset i'rom the center line of said guide post to afford a leverage means on said contact carriage Ifor tilt- :ing said carriage upon engagement of said contacts and provide s, wiping engagement thereof, and a spacing washer interposed between the upper end of said spring means and said extension on said member, said washer having a portion encirciing said guide post, a pair of diametrically opposed inwardlyY extending portions on said washer projecting into said slot in said guide post, the ends of said 'portions being spaced apart slightly less than the thickness oi' the top oi"y said guide post to prevent said washer from :.ialling ofi the said guide post when switching device is assembled.

ALLEN G.

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