US2946876A

US2946876A - Relay structure

Info

Publication number: US2946876A
Application number: US470369A
Authority: US
Inventors: Edwin H Lockwood; Rexford W Brenneman
Original assignee: Consolidated Electronics Industries Corp
Current assignee: Consolidated Electronics Industries Corp
Priority date: 1954-11-22
Filing date: 1954-11-22
Publication date: 1960-07-26
Anticipated expiration: 1977-07-26

Description

y 1960 E. H. LocKwooD EFAL RELAY STRUCTURE 2 Sheets-Sheet 2 Filed Nov. 22, 1954 United States Patent ice My RELAY STRUCTURE Edwin H. Lockwood, Frederick, and Rexford W. Brenneman, Woodsboro, Md., assignors to Consolidated Electronics Industries Corp., New York, N.Y., a corporation of Delaware Filed Nov. 22, 1954, Ser. No. 470,369

27 Claims. (Cl. 200-104) This invention relates to a relay structure for miniature relays. More particularly it deals with relays for use in electrical and electronic systems where weight and space must be conserved as much as possible without reducing the amount of electricity or the number of cir cuits to be controlled, such as for example in the electronic control circuits for aircraft or/and the like including guided missles and rockets. The specific features of the relay of this invention reside in the construction of the magnetic pole pieces, the contacts and the means for positively operating the contacts.

Usually in small relays the poles of the electromagne ts are so small and must be placed so close together that such relay cannot have much power and the contacts could easily be jarred together or apart, particularly if the contact pressure was low and/ or the relative distance and movement between the contacts was small. This small distance also produced arcing when high currents and voltages were employed.

It is an object of this invention to produce a simple, efficient, effective and economic miniature relay.

Another object is to produce such a relay having positively acting magnetic and electrical circuits.

Another object is to produce such a relay with a relatively small contact gap that does not are and cannot be closed by shock or vibration.

Another object is to produce such a relay having relatively large areas on the electro magnetic pole pieces that are separated from each other.

Another object is to produce a miniature relay which is balanced statically and dynamically which will Withstand considerable vibration and shock and does not de-' pend upon contact pressure to remain in a fixed position.

Another object is to produce such a miniature relay which is easy to assemble and adjust and is readily adaptable for different purposes, such as increasing or decreasing the number of contacts, changing the electrical contacts to ma'ke before break, or break before make as desired, and the like.

Generally speaking, the relay of this invention has a hollow center in its electromagnetic coil, through which center the armature of the relay is pivoted and around which coil is provided a magnetic housing for completing the magnetic circuit through the armature. The effectiveness of the magnetic circuit is increased by providing one or both of the pole pieces at opposite ends of the coil with an extension which extends part way into the hollow center of the coil to provide an increased surface area for cooperation with the pivoted armature. The pivoted armature is pivoted perpendicular to the axis of the coil of the relay either inside the coil of the relay or near its end. The deenergized position of the armature in the relay may be maintained by physical means, such as a tension or compression spring, directly operating on the pivoted armature whose force may be limited and adjusted by a set screw and/or an armature abutment stop.

The movement of the electrical contacts of the relay by the oscillating movement of the armature is effected by a reciprocating insulated interrupter leaf connected to an end of the armature, which leaf is provided with camming surfaces that engage abutments adjacent the leaf springs carrying the movable one of each pair of contaots, to first move the springs carrying the movable contacts to separate them from their cooperating stationary contacts, and immediately thereafter to insert a thin portion of the interrupter leaf in the space or gap just produced between the cooperating contacts to prevent later shock or vibration from closing these contacts and to break any arcs that may occur between them as they are separated. One or more cooperating pairs of contacts may be operated by the same reciprocating interrupter leaf connected to the armature, which leaf may be shaped or the location of the abutments on the leaf springs may be changed to cause one or more contacts to break before another one is made, or vice versa, as desired. The electrical contacts themselves may have dilferent shapes depending upon the amount of voltage and/0r currents the contacts are to carry so as to reduce the arcing as much as possible.

The whole relay assembly including the contacts may be placed in a can or container which may be hermetically sealed or not, and the contact interrupting leaf operated by the armature of the relay may be located at either or both ends of the relay, however, it is desirable to locaite it at the end away from the electric terminals to the relay so that the relay contacts will not be affected by any heat which may be used during its assembly or soldering to connecting circuits.

The above mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of embodiments of this invention taken in conjunction with.

the accompanying drawings, wherein:

Fig. 1 is an exterior assembled side elevational view of a relay according to this invention shown in the patent drawing at approximately its actual size;

Figure 2 is an enlarged sectional view taken along line 11-11 in the relay of Fig. 1 with the armature shown in its energized position;

Fig. 3 is a right hand end view of the relay shown in Fig. 2 taken along line III-III of Fig. 2;

Fig. 4 is a view of the lower left portion of Fig. 2 with parts broken away but with the armature shown in its deenergized position;

Fig. 5 is a full side elevation of a pair of the magnet pole pieces employed in the embodiment shown in Fig. 2;

Fig. 6 is a plan view of Fig. 5 showing how a pair of pole pieces may be produced from one piece of material;

Fig. 7 is a left end view of the armature shown in 'Fig. 2 with parts broken away showing the connection of the spring to the end of the armature;

(Fig. 8 is a vertical section of a modified form of magnetic housing for the electromagnetic coil and armature shown in Fig. 2;

Fig. 9 is a left end view of the modified magnetic housing shown in Fig. 8;

Fig. 10 is a side elevational view of another embodiment of an electromagnet coil and housing assembly with the armature pivoted at the end of the coil instead of in the center as shown in the previous embodiments;

Fig. 11 is an enlarged plan view of the contact carrying plate at the left hand end of the relay shown in Fig. 2 with part of the contacts and contact actuating leaf being broken away.

Fig. 12 is a vertical section taken along line XII-XII of Fig. 11 showing the connection between the end of the armature and the contact interrupting leaf through the contact carrying plate;

Fig. 13 is a section taken along line XIII-XIII of Fig. 11 showing the operation of one pair of contacts and the contact operating plate;

Fig. 14 is a separate plan view of the contact actuator or interrupter leaf shown in Fig. 11;

Fig. 15 is a right hand view of the interrupter leaf shown in Fig. 14;

Fig. 16 is a sectional view along line XVI-XVI of Fig. 14 through the center of the interrupter plate;

Figs. 17 and 18 are enlarged side elevational and plan views, respectively, of the type of electrical movable contact shown in Figs. 2, 4 and 13;

Figs. 19 and 20 are similar to Figs. 17 and 18, respectively, showing another type of electrical contact having concave faces; and

Figs. 21 and 22 are also similar to Figs. 17 and 18, respectively, showing still another type of electrical contact having convex faces.

Since a relay comprises both magnetic and electric circuits and the structure of the relay of this invention involves new features in both of these circuits in order to carry out the objects of this invention, the following description will be divided into the (I) magnetic structure specifically shown in 'Figs. 110 together with modifications thereof, and the (II) electrical structure specifically shown in Figs. 11-22 with modifications thereof.

I. The magnetic structure Referring specifically to Fig. l, a side elevation of a relay having a six poles or six separate input electrical circuits which may be connected or disconnected by the pairs of contacts of the present relay, is disclosed sealed within a can or container 25 which forms a protective shell over the relay. At one end and the open end of this can 25 may be located all of the electrical terminals 26 of which there are twenty in this specific embodiment. Surrounding the container 25 adjacent the terminals 26 may be provided a ring mounting plate member 27 which may have one or more ears 28 to which mounting means, such a bolts 29, may be fastened for anchoring the relay assembly.

Referring to Fig. 2, the terminals 26 may be mounted in an insulating plate or mounted in glass sleeves 30 fastened in a metal plate 31, which plate 31 may then be filleted or soldered at 32 around its edges to the open end of the container 25. If desired the relay may be hermetically sealed in the container with an inert gas or dry air so that its contacts will not be affected by the changes in moisture, temperature, pressure or other factors of the atmosphere surrounding the relay.

In the specific embodiment shown, the stationary path or magnet of the magnetic circuit may comprise a rigid cylindrical magnetic housing member 35 which may completely surround the cylindrical bobbin 36 having a hollow cylindrical core 37 upon which the coils of wires 33 of the electromagnet are wound. This magnetic cylindrical housing 35 is shown to extend beyond the end of the bobbin 36 to provide integral connection with diametrically opposite segmental shaped

magnetic end plates

40 and 41. Each of these

end plates

40 and 41 are herein shown to be provided with three radial tapped holes 42 into which three separate screws 43 and 44 may be screwed for anchoring the arcuate periphery of the pole pieces to the inside of an end of the cylindrical housing member 35 to form as effective a magnetic connection as possible with the cylindrical housing 35. The fiat chord edge 46 of the pole pieces of each of the

end plates

40 and 41 provides an effective surface for cooperation with the fiat ends of the pivoted armature mounted in the hollow center 37 of the bobbin 36. In order to increase the effective surface of contact between the cooperating surfaces of the armature and the pole pieces, there is provided according to this invention, integral cylindrical

segmental extensions

47 and 48 on each of the pole pieces of the

end plates

40 and 41, respectively, which extend less than halfway across and part way into the hollow center 37 of the coil from each end as shown in Figs. 2 and 4, so that in effect the surfaces 46 of contact of the poles are materially increased along the

cooperating surfaces

53 and 54 of the armature 50, thereby increasing the magnetic power of the electromagnet.

In the embodiment shown in Figs. 2-9, the oscillating armature 50 is pivoted substantially in the center of the bobbin 36 on a first pin 51 perpendicular to the axis of the bobbin. This pin 51 may be mounted and assembled inside of the bobbin 36 before the coil wires 38 are wrapped thereon. The bobbin 36 and pin 51 accordingly may be made of brass or other maleable metal, or the bobbin may be made of plastic, and may be provided with a central internally extending rib 52 to form a stronger anchor for the ends of the pin 51. This solid cylindrical armature 50 is preferably made of a magnetic ingot or powdered iron, similar to that of the housing 35 and pole pieces and

end plates

40 and 41, and has its outer edges stepped or flattened and narrowed forming the

surfaces

53 and 54. Thus the armature 50 has a portion away from the pole pieces thereof of greater cross-sectional area so as to provide less magnetic reluctance or better magnetic flux and cooperation with the surfaces 46 and

extensions

47 and 48 of the pole pieces on the

end plates

40 and 41, as well as to permit angular movement free from the inside edge of the hollow section 37 illustrated by the deenergized position of the armature 50 shown in Fig. 4. At one end of the armature, adjustably mounted in the edge of the magnetic housing 35, may be provided a set screw 60 for limiting the deenergized position of the armature 50 to that position shown in Fig. 4. Also at an end of the armature, herein the opposite end from that of the set screw 60, there may be provided a means such as tension spring 61 which normally maintains the armature in the position shown in Fig. 4 when the electromagnetic coil 38 is not energized. This spring 61 also may be adjustably mounted in the housing 35 by means of a set screw 62 connected to one end of the spring 61, while the other end of the spring may be fastened into a bail 63 (see Fig. 7) connected to opposite sides of the armature 50. Beyond this or the other or both ends of the electromagnet may be provided a portion 65, which may be integral with the armature and which extends outside of the electromagnetic assembly and pole pieces, which herein is shown to have a square cross section, to which the actuator of the contacts or interrupter leaf 136 of this relay may be connected, as will be described later in the electrical structure part of this description.

The electromagnetic assembly, including the coil 38, its housing 35,

end plates

40 and 41, their pole pieces and

extensions

47 and 48, and the armature 50, may be mounted onto the terminal plate 31 by means of a pair of non-magnetic (such as brass) legs or pegs 70 and 71 having offset portions engaging the end of the housing 35 and provided with holes for screw 43 to fasten to the housing and end plate 40 and for screw 72 for fastening the leg 70 to the other side of the housing. An aperture 73 may also be provided in leg 70 through which the set screw 60 may readily be adjusted after the support leg 70 is anchored with the terminal plate. The base ends of the supporting

legs

70 and 71 may be provided with tapped holes 74 for the insertion of screws 75 through the terminal plate member 31 for anchoring the electromagnet and its terminal plate together.

The container 25 for the whole relay assembly may be anchored to the electromagnet structure assembly by means of screws 75 on opposite sides of the electromagnet substantially in line with the axis of pin 51, which screws 75 fit into internally and externally threaded stud members 76 which are in turn screwed into threaded holes in the sides of the magnetic housing 35 as shown in Fig. 3.

Instead of employing

separate end plates

40 and 41 as shown in Figs. 2, 3 and 4, the structure of the housing member may be made integral with one of the end plates as shown in Figs. 8 and 9, namely, a cup-shaped magnetic housing member 80, corresponding to housing 35 and end plate 41, mm one endof the member 80 having a segmental portion 81 corresponding to the. pole piece of the end plate 41, but which need not also contain an internally projecting portion 48 for ease in manufactureand because the effective magnetic circuit between the cylindrical housing 80 and the end plate portion 81 is now increased by forming an integral one piece structure. Thesame end of the housing 80 may also be provided with extensions 82 (see Fig. 9') adjacent one pair of tapped holes 83 to provide reinforcement material around these two holes. The other portions ofjthe structure of this modified form are substantially the same as those previously and later described for the form shown in Figs. 2 and 3.

In Fig. there is shown a side elevation of still another electromagnetic assembly having an outer magnetic cylindrical housing 90 around an electromagnetic coil 91 having a hollow central section 93 through which a pivoted armature 94 is mounted to cooperate with an inwardly extending pole piece 95, similar to pole plate 40 and its pole piece extension 47 previously described. The pivot 96, however, for this armature 94 is shown at one end of the armature and electromagnetic coil 91, andv adjacent thereto a compression spring 97 may be provided for normally maintaining the armature 94 in the deenergized position shown in Fig. 10. The other end of the armature 94 is shown to have an integral extension portion 98 projecting beyond the face of the end Referring now specifically to the electrical structure of the miniature relay of this invention, reference will be had now to Figs. 11-22 as well as Figs. 1, Zand 4, which latter three figures show the electrical connections between the terminals 26 mounted in the terminal plate 31 via separate insulated conductor wires 100, which may be soldered to the inner ends of the terminals 26 and extend through the space 101 between the magnetic housing 35 and shell '25 to the contact carrier plate assembly 105 mounted by screws 106 in tapped holes 83 at the opposite end of the electromagnet from the

legs

70 and 71. This carrier plate is herein shown to comprise two parallel disks of non-electrical conducting material, such as for example nylon, silicon glass laminate, or other relatively rigid non-conductive material. A plan view of the outer carrier plate 107 is shown in Fig. 11 upon which may be printed or located the metallic or copper

pad conducting circuits

108, 109 and 110 which connect the three different sets of electrical terminals and contacts provided in the six pole relay structure disclosed herein, with the separate notches 111 with adjacent holes 112 around the periphery of the carrier plate 105. The wires 100 are fitted into these notches 111'and their conducting wire portions 114 are bent over the top of the conducting or printed

strips

108, 109 or 110 and then back into the holes 112 (see Figs. 11 and 13) to form a positive connection, which may be then also soldered at 115 to form a still more positive electrical connection.

The second or inner plate 116 of the contact carrier 105 may be provided with enlarged holes 117 beneath some of the pins and

contacts

118 and 119 mounted on the plate 107 to provide space for the peened over rivet type ends of these contacts and pins so as to present a non-conducting and smooth surface for anchoring the carrier plate 105 onto the end of the electromagnet. Thus, ea'chof the three rows of sixelectrical contacts and terminals mounted on the carrier plate 105 in Fig. 11

may separately be connected to 18 dilferent wires 100 which may be connected to separate terminals 26 mounted on the terminal plate 3-1. This terminal plate 31, however, is provided with twenty separate contacts, providing two terminals for the conductors to the electromagnetic coil 38. It is not necessary, however, that all of the contacts have separate connections, or that all six poles be employed in that other relays with'fewer number of contacts or poles may be operated and controlled similarly to the one herein described Without departing from the principle of this invention.

By arranging the circuits on the contact carrier plate in the manner shown in Fig. 11, spaces have been allowed for the attaching screws 106 at three different locations so that the contact carrier assembly 105 may be screwed on and remo'ved from the electromagnetic assembly without the removal or readjustment of any of the contacts on it as shown in Fig. 11. This particular structure also provides a positive location for the mounting of the contact carrier 105 and its alignment with the operating

portions

65 or 98 of the armatures.

The specific electrical contact assembly disclosed in this type of relay has six input conductors connected through the six printed circuits 109 to the central row of six separate terminal posts 120, which herein are shown riveted to both the

plates

107 and 116 for holding these plates together. Six electrically conductive leaf springs 121 are fastened at their centers to the po'sts 120 such as by means of screws 124, and at the outer ends of each of said springs are provided the movable electrical contacts 122, which alternately cooperate with the fiat tapped

electrical contacts

118 and 119. These

contacts

118 and 119 and/or 122 may be made of special metal, such as palladium. The springs 121 as shown in Fig. 13 are normally convex toward the left so that the contacts 122 are normally urged toward their corresponding stationary

flat contacts

118 and 119. These springs 121 may be made out of phosphorous bronze or beryllium copper alloys. Each of the contact springs 121 are also provided with cam abutment buttons or means 123 fastened inwardly from the ends of the springs and the contacts 122.

Between the springs 121 supporting the movable contacts 122 and the contact carrier plate is provided the non-electrically conductive contact actuator or inter rupter leaf which may be made of nylon, silicon resin, glass, polytetrafiuoroethylene polymer, polymonochlo'rotrifluoroethylene polymer, or other rigid non-conducting material. A separate view of this actuator leaf 130 alone is shown in Figs. 14, 15 and 16 and part thereof is shown in position in Figs. 11 and 13. This contact actuator 130 may be provided with a square central opening 131 which fits over the square outer

extended end

65 or 98 of the armatures '50 or 94, respectively, so as not to rotate thereon, and be reciprocated back and forth with the motion of the armature 65 in the direction of the arrows 132 shown in Fig. 11. For more positively guiding the movement of this actuator leaf 130 there may be provided supporting and guiding pins 133 mounted on the plate 107 as shown in Fig. 12, which pins may be provided with shoulder portions 134 for supporting the under side of the leaf 130 and narrower projecting pin portions 135 which extend through elongated slots 136 provided in the plate for guiding the plate in its movement in the direction of the arrows 132. In the leaf 130 are a plurality of apertures or

openings

137 and 138 through and in which the spring contacts supporting posts 1'20 may extend. These posts also may act as guides for the actuator leaf and prevent its rotation about the armature 65. Additional supporting pins 139 may be located under the center of each quadrant of the.

leaf 130 (see Figs. 11 and 13) upon which rests the lower surface of the sliding leaf 130 to insure that the leaf 130 remains spaced. (140) at all times above andout of contact with the flat

stationary contacts

118 and 119 and not cause any insulation material to be deposited or rubbed off on these electrical contacts. The upper surface of the interrupter leaf 130 which is adjacent the abutments 123 on each of the leaf springs 121 is provided with a cammed face or sloping step portion 141 (see Figs. l3, l4 and 15) which cooperates with the abutments 123 to raise or separate the movable contacts 122 as the abutments 123 slide up the step portions 141 into the position shown at the upper end of Fig. 13. This wedging movement of portions 141 under an abutment 123 separates its corresponding contact 122 from its normal position against the fiat top of the stationary contact 118 and simultaneously thereafter slides the thin narrow edge portion 142 o'f the interruptor leaf into the center of the gap or space 140 between the two contacts to prevent the contacts from being jarred together or made and also to break any are which may occur between the two contacts during their separation.

By this wedging action for operating the movable contacts 122 less force is required for separating the contacts 122 from their stationary contacts than by direct pull and therefore more force may be applied by the springs 121 to prevent separation of the contacts by vibration or shock. Furthermore, the fact that an additional insulation leaf 142 is inserted in the gap 140, a smaller gap may be tolerated for breaking circuits having given potentials. The continued pressure by spring 121 on abutment 123 against the interrupter leaf 130 also dampens the motion or vibration of the movable contact 122 while in its open position.

The thin portions 142 which are inserted in the space or gap 140 between the

open contacts

122 and 118 or 119 need not necessarily extend the full length of the leaf 130 so that the thicker portions of the leaf will form a reinforcement around these apertures 136 as shown in Figs. 11,14 and 16.

The location of the cammed edge 141 and/or of the abutment means 123 on the leaf springs 121 may be changed so that the

contacts

122 and 119 may be broken before the

contacts

122 and 118 are made, or so that they may be broken after the contacts are made. If desired, different cammed surfaces for different sets of contacts may be provided Within the same relay either by reshaping the steps 141 on interruptor plate 130 and/or relocating the abutment means 123 along the springs 121.

Enlarged views of a contact 122 are shown in Figs. 17 and 18 in which an elongated flat contacting surface 145 is flanked by fiat tapered sides 146 to restrict the gap 140 sharply to the area of the flat surface 145. If desired these tapered sides from the surface 145 may concave, as sides 147 shown in Figs. 19 and 20 to further increase the side gap for circuits in which more arcing or voltage may occur. However, if high current carrying contacts are required having greater contact surfaces, convex sides 148 as shown in Figs. 21 and 22 may be employed. fact different shaped contacts may be provided for different circuits in the same relay, without departing from the scope of this invention.

The shape of the abutment cam 123 may be similar to that of the contacts 122 shown in Figs. 17 and 18, so as to provide as much a camming surface along the step portion 141 as possible, however, other configurations of these abutments may be provided, such as forming the spring 121 to create a V shape similar in outline and location to abutment cam 123, without departing from the scope of this invention.

While there is described above the principles of this invention in connection with specific apparatus it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of this invention.

What is claimed is:

1. An electromagnet having a coil with a hollow center and a pivoted armature movable transversely of the axis of said coil in the hollow center of said coil, the improvement comprising: a pair of magnetic end plates for said coil, at least one of said end plates having an at' tached pole piece, magnetic means for magnetically con-. necting said end plates together outside ofsaid coil, said pole piece extending part way across the open end of said hollow center and having an integral extension extending part way into said coil, whereby said armature has a surface of magnetic attraction adjacent said pole piece and its said extension.

2. An electromagnet according to claim 1 wherein each of said end plates has an attached pole piece.

3. An electromagnet according to claim 2 wherein each of said pole pieces has an integral extension extending part way into the hollow center of said coil.

4. An electromagnet according to claim 1 wherein said armature is pivoted inside said coil on an axis perpendicular to the axis of said coil.

5. An electromagnet according to claim 1 wherein said armature is pivoted between its end and is provided with a surface magnetically co-operating with the surface of said pole piece and its integral extension.

6. An electromagnet according to claim 1 wherein said armature is provided with a greater cross-sectional area away from its portion which co-operates with said pole piece, whereby the magnetic reluctance in the electromagnet is reduced as much as possible through the armature between said end plates.

7. An electromagnet according to claim 1 wherein said magnetic means comprises a housing for said coil.

8. An electromagnet according to claim 1 wherein said pole piece extends less than half way across the open end of said hollow center.

9. An electromagnet according to claim 1 wherein said end plates are segment shaped and cover approximately half the end area of said coil with their chords parallel to the pivotal axis of said armature.

10. An electromagnet according to claim 1 wherein the portion of said armature that magnetically co-operates with said pole piece and its said extension are shaped to produce a uniform air gap between their adjacent magnetically co-operating surfaces in at least one position of said armature.

11. An electromagnet having a coil with a hollow center and an armature pivoted perpendicular to the axis of the coil in said hollow center of said coil, the improvement comprising: a pair of magnetic end plata for said coil, at least one of said end plates having a pole piece, said pole piece extending part way across the open end of said hollow center and having an integral extension extending part way into said hollow center of said coil, said armature having a cross-sectional shape in its portion away from said pole piece and its said extension similar to the cross-sectional shape of said hollow center with clearance space from the surface of said hollow center to permit free motion of said armature, the end portion of said armature adjacent said pole piece and said extension being shaped so as to co-operate magnetically with said pole piece and said extension, whereby magnetic reluctance of said electromagnet through said armature is made small, and magnetic means for magnetically connecting said end plates together outside said coil.

12. An electromagnet according to claim 11 wherein each of said end plates has a pole piece.

13. An electromagnet according to claim 12 wherein each of said pole pieces has an integral extension extending part way into the hollow center of said coil.

14. An electromagnet according to claim 11 wherein said pole piece has a segmental shape and covers approximately one half the end area of said coil, the chord of said segment being parallel to the pivotal axis of said armature.

15. An electromagnet according to claim 11 wherein said pole piece extends less than half way across the open end of said hollow center, whereby said pole piece with its said extension and said armature substantially fill the hollow center of said coil except for the space necessary for the movement of said armature.

16. A relay having a coil with a hollow center, a pivoted armature movable transversely of the axis of said coil in said hollow center of said coil, and electrical contacts operated by the movement of said armature, the improvement comprising: a pair of magnetic end plates for said coil, at least one of said end plates having a pole piece, magnetic means for magnetically connecting said end plates together outside of said coil, said pole piece extending part way across the open end of said hollow center and having an integral extension extending part way into the hollow center of said coil, whereby said armature has a surface of magnetic attraction adjacent to said pole piece and its said extension, and a non-electrically conductive means connected to said armature for operating said electrical contacts.

17. A relay according to claim 16 wherein said armature comprises an integral extension extending beyond at least one of saidend plates for operating said non-elec trically conductive means.

18. A relay according to claim 17 wherein said nonelectrically conductive means comprises a plate parallel to said end plate and movable in the plane of said non electrically conductive plate by said extension.

19. A relay according to claim 16 wherein said electrical contacts comprise at least one stationary contact and at least one movable contact, and said relay includes means for urging said movable contact into contact with said stationary contact.

20. A relay according to claim 19 wherein said nonelectrically conductive means co-operates with said means for urging said movable contact in contact with said stationary contact to move said movable contact away from said stationary contact.

21. A relay according to claim 20 wherein said means for urging said movable contact includes an abutment for cam operation with said non-electrically conductive means.

22. A relay according to claim 16 wherein said nonelectrically conductive means includes means for inserting an insulating leaf between the gap between said contacts.

23. A relay according to claim 22 wherein said insulating leaf is inserted after said contacts have been separated, and said insulating leaf is spaced from both of said contacts in said gap.

24. In a relay having an electromagnetic coil, a movable armature and a pair of contacts operated by said armature, the improvement comprising: an insulation contact interrupting leaf member movable by said armature, cam means on a movable one of said contacts for cooperating with said insulation leaf member to move the movable contact relative to the other contact, and an insulation partition extension on said insulation member adapted to freely pass within the space between and spaced from said contacts after they have been separated by. said cam means to increase the effective gap between said contacts and to prevent rubbing of said insulation member over the contacting faces of said contacts.

25. A relay according to claim 24 including an abutment on said movable member for cooperating with said cam means.

26. A relay according to claim 24 including means for normally maintaining said movable contact urged into contact with said non-movable contact and said cam means.

27. An electrical switch comprising: an insulating base member, a stationary contact, a movable contact operable in said stationary contact for making and breaking an electrical circuit, a leaf spring member carrying said movable contact, means for supporting said spring member above said base and remote from said contact, and said leaf spring normally urging said movable contact into contact with said stationary contact, an abutment means mounted on saidleaf spring member between said movable contactand its said supporting means and projecting outwardly from said spring member toward said base member, an operating member movable between said spring member and said base member parallel to said base member, said operating member having a stepped cam surface cooperable with said abutment to flex said spring member away from said stationary contact to separate said contacts by a space, and a separator portion thinner than said space and mounted on said operating member which moves into said space between said contacts but out of contact with said contacts after said operating member has separated said contacts.

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