US2682584A - Relay - Google Patents

Description

June 29, 1954 H. M. KNAPP 2,682,534

RELAY Filed May 24, 1952 2 Sheets-Sheet :l

M/l ENTOR By H. M. K/VA PP fcQ A T TOR/V5 V June 29 1954 H. M. KNAPP 2,682,584

RELAY' Filed May 24, 1952 2 Sheets-Sheet 2 #vvavroe By H. M. KNAPP Patented June 29, 1954 UNITED STATES PATENT OFFICE RELAY Harry M. Knapp, Scotch Plains, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application May 24, 1952, Serial No. 289,842

11 Claims. 1

This invention relates to switching devices, and more particularly to switching devices for controlling a multiplicity of electrical circuits.

An object of this invention is to improve the efliciency, the compactness and the economy of manufacture and maintenance of switching devices.

A further object of this invention is to improve the facility of a switching device to transfer a first lead from a second to a third lead.

Another object of this invention is to increase the number of circuit-controlling elements of a switching device without increasing the overall dimensions of the device.

A further object of this invention is to increasethe number of circuit-controlling operations which a switching device can perform.

A feature of this invention is an insulating element which not only serves accurately to fix the position of a plurality of contact elements, but also. serves to guide the movement of certain other contact elements.

Another feature of this invention is the obtaining of transfer and continuity types of contact operation with but a single group of contact elements.

The principles of the invention have been exemplarily embodied in two types of electromagnetic switching devices or relays. The nature of the invention may most clearly be understood from the following detailed description of those two embodiments of the invention, when read with reference to the accompanying drawings in which:

Fig. 1 is a plan view of one preferred embodiment of the invention partially cut away to show certain details of the construction more clearly;

Fig. 2 is an elevational view of the relay shown in Fi 1;

Fig. 3 is a front-end view of the relay shown in Fig. 1;

Fig. 4 is an elevational view of a second pre ferred embodiment of the invention, partially cut away to show certain details of the construction more clearly;

Fig. 5 is an elevational view of the relay shown in Fig. 4; and

Fig. 6 is a front-end view of the relay shown in Fig. 4 partially cut away to show certain details more clearly.

- The relay disclosed in Figs. 1 to 3 of the drawings is also disclosed, and claimed, in the patent application of H. M. Knapp and C. F. Spahn, Jr., Serial No. 289,843, filed on even date herewith.

Referring first to the embodiment of the invention disclosed in Figs. 1 to 3 of the drawings, the relay there disclosed comprises an E-shaped core having three leg portions, I, 2 and 3 and a bridging portion 4 which serves to interconnect the leg portions I, 2 and 3. Removably placed upon the center one of these leg portions 2 is an electromagnetic coil 5 having a front spoolhead 6. The terminals of the coil 5 are connected to wires I which are mounted in the front spoolhead 6 and extend rearwardly of the relay through apertures in a molded element of insulating material 8 and appear at the rear of the relay as terminals to which external circuits may be connected. A plurality of these terminal wires 7 are provided so that coils having multiple windings may be employed if desired.

The molded block 8 is substantially L-shaped in cross-section (the L being inverted in the showing of Fig. 2) whereby a flat surface is provided against which the upper side of the bridging member 4 or" the core may rest. However, interposed between the upper surface of the bridging member A and this surface of the molded block 8 is a flat U-shaped spring member 9. By

' virtue of this construction, the bight of the U- shaped spring member 9 is clamped between the lower surface of the oi fset portion of the molded block 8 and the upper surface of the bridging element of the core.

The two leg portions of the spring member 9 extend forwardly in spaced proximity to the outer core legal and 3. The extreme forward ends of the legs of the spring member 9 are provided with extending flange portions which may be wrapped or clinched around the tip ends of the legs IQ of the armature I I whereby the spring member 9 serves as a means for hinging the armature and for biasing that armature to its unoperated position. The clinched ends of the legs of the spring member 9 may further be attached to the legs In of the armature II by welding, if

desired.

The armature I I is essentially U shaped in appearance, the bight of the U extending across the relay so as to be capable of bridging the three legs I, 2 and 3 of the core. The leg portions ID of the armature I I extend rearwardly of the relay and the tip ends of the legs Iii rest against the legs of the spring member 9, which in turn rest against the outer core legs I and 3. Therefore, the armature H is pivotally mounted, the fulcrum being approximately at the extreme ends of the legs It of the armature II. The legs Iii of the armature i I may be of any suitable length depending upon the operational requirements of 3 the relay. Thus, in the embodiment of the invention disclosed in Figs. 1, 2 and 3, the armature legs have been made substantially as short as possible and still provide a sufficient air-gap between the bight of the relay II and the central core leg 2.

It will be seen that the electromagnetic circuits of the relay include a first circuit comprising the center core leg 2, the core bridging member 4, the outer core leg I, leg If! and the bight of the armature II, and an air-gap between the armature and the core. A similar path exists including core leg 3 and the other leg IQ of the armature II. Therefore, upon energization of the coil 5, a force will be exerted tending to pivot the armature I I to a position in which it bridges the three core legs I, 2 and 3, i. e., the forwardmost edge of the armature II will tend to move downwardly to engage the core, in the showing of Fig. 2.

Three layers of contact-holding elements are provided, and in the preferred embodiments of the invention these contact-holding members are in the form of thin wires. The lowermost layer 50 and the uppermost layer 52 of wires are movable, under the control of the armature, relative to the centermost layer of wires I. As may best be seen in Fig. 2 of the drawings, the lowe1=- most set of these wires 5!! is molded or otherwise mounted in an insulating member I2 which engages the upper edge of the molded block 8. The centermost layer of wires 5I, which are preferably of heavier construction than the lower and upper layers of wires, are mounted in an intermediate block of insulating material I3 which rests on block I2. To provide the requisite rigidity, it is advantageous to provide a forward extension I4 for the block I3. The center-most layer of wires 5| are preferably mounted in the block I3 and in its forward extension I4 during the operation in which blocks I3 and I4 are molded. Similarly, the upper layer of springs 52 are molded or otherwise afiixed in an upper molded block of insulating material I5 which abuts the upper surface of block I3. Abutting the upper edge of molded block I5 is an essentially U-shaped balancing spring member It, the function of which will hereinafter be described.

In order accurately to position and retain the bridging portion 4 of the core, the molded blocks 8, I2, I3 and I5 and the balancing spring It in fixed position relative to one another, it is advantageous to provide corresponding projections and indentations in the several elements. For example, the balancing spring member I6 is apertured to engage projections ll on the upper block I5. This group of elements is firmly rendered integral by means of a clamp which has a top portion I8 and two leg portions I9. The top portion I8 firmly engages the upper surface of the balancing spring member It and the leg portions I9 are .provided with inwardly extending projections which engage the edges of the undersurface of the bridging portion 4 of the core. The upper surface I8 of the clamp may be suitably deformed to provide a spring action.

The centermost layer of spring members 5| are affixed, preferably during the molding op eration, in a front molded block member 23, and pass through that front molded block 23. Springs 5I are provided at their forwardmost ends with contact elements 24. As may best be seen in Fig. 3 of the drawings these contact members 24 are preferably square or rectangular blocks of metal with relatively thin layers of precious or legs I, 2 and 5 accurately in a plane.

semi-precious contact metal at their upper and/ or lower edges.

In order that the centermost layer of fixed springs 5|, which are integral with the front molded block 23, may be securely immobilized, a core plate 25 is provided. This core plate 25 performs a plurality of functions. It is affixed to the front ends of the core legs I, 2 and 3 by apertures in the plate 25 securely engaging these legs. This serves not only to retain the core plate in position, but also greatly improves the economy of manufacture of the relay. The three apertures in the core plate 25 which engage the core legs I, 2 and 3, may be accurately located at relatively small cost. When the core plate is assembled to the core, the core plate then serves accurately to position the three legs I, 2 and 3 of the core with relation one to the other. Therefore, there is no necessity for machining the core legs to close tolerances and no necessity for maintaining the upper surfaces of the core The core plate serves to force those upper surfaces to be coplanar when the relay is assembled.

A portion 26 of the core plate 25 is bent forwardly so as to rest in proximity to a central forward extension 21 of the armature II. This projection 26 serves as a back stop for the armature, i. e., it defines the unoperated position of the armature. By virtue of this construction the back stop is centrally located on the armature and is positioned in line with the member 30 upon which the armatures force is exerted. It has been found that if the line of the armatures output force passes through the back stop member, armature rebound is substantially obviated.

The core plate 25 is also provided with two projecting arms comprising horizontal portions and 46 and vertically extending portions 41 and 48. The front molded block 23 rests against the uppermost edges of the upstanding arm portions 47 and 48, being firmly held against those portions primarily by the downward force exerted by the pretensioned single fixed springs 5| and also by the downward force exerted by the pretensioned twin springs 52. The horizontal portions 45 and II; are apertured so that a tool may be inserted to bend the horizontal portions 45 or 46 up or down to adjust the position of the front molded block 23 and thus to adjust the position of the fixed contact elements 24 relative to the movable springs 50 and 52.

The upper and lower spring members 52 and 50, respectively, extend forwardly in approximate parallelism with one another and with the fixed springs 5|, are provided with downwardly and upwardly extending offset portions, respectively, at their forwardmost ends, and terminate in precious or semiprecious metal contact elements. As may best be seen in Fig. 3 of the drawings, two

. upper springs 52 and two lower springs 50 are provided for each contact element 24 of each fixed spring 5| so that upon any contact closure two independent contacts engage a single fixed contact. This construction reduces the possibility of malfunctioning of the relay due to dust or other impediments.

The upper springs 52 and the lower springs 50 are controlled by a moving card 30 of insulating material. The member 30 is generally rectangular in external configuration and is suitably apertured to perform its necessary functions. The upper layer of springs 52 rest against the uppermost edge 35 of the card 30; the lowermost layer of springs 50 are engageable by an edge 36 of the moving card 30. The card is moved downwardly upon the operation of the relay by virtue of an engagement of a portion 31 of the card 30 with forwardly extending projections 38 of the armature H.

The uppermost layer of springs 52 are bent so as to be pretensioned in a downward direction. Theupper springs 52 therefore continuously exert a force downwardly on the moving card 30 so that upon the downward movement of card 39 as a result of the operation of armature II, the upper layer of springs 52 are permitted to move downwardly to engage the fixed contact elements 24. Similarly, the lower layer of springs 50 are bent so as to be pretensioned upwardly into engagement with the fixed contact elements 24. Therefore, upon a downward movement of the moving card 30, the lower springs 50 are forcibly separated from the fixed contact elements 24.

Upon the release of the relay and the return of the armature I l and the moving card 30 to their normal positions as shown, the upper layer of springs 52 will be forced back to their normal positions, as shown, and the lower layer of springs 50 will be permitted to return to engagement with the fixed contact elements 24.

The movement of the springs 52 and 50 both upon the operation and the release of the relay is controlled not only by the moving card 3!) but also by the front molded block 23. Thus, a plurality of tooth-like projections 43 are provided on the upper surface of the front molded block and the upper movable springs 52 are accurately laterally positioned and guided thereby during their movement. Similarly, a plurality of projections 44 are provided on the lower surface of the molded block 23 to guide the lower springs 50 during their movement. By virtue of this arrangement, accurate lateral engagement of the moving springs within the fixed contact elements is assured.

In certain uses of the relay the moving springs may be subjected to high-frequency vibratory chatter upon the operation or release of the relay. To avoid this condition, a shock absorbing material 54 may be affixed to the portion 14 of the molded block 43 so as to press against the moving springs 50 and 52 to damp vibrations of those springs.

It will be noted that in the embodiment of the invention shown in Figs. 1 to 3 which represent a relay of conventional size, there are twelve groups of contact elements, each of which groups may comprise a fixed contact element, an upper twin contact element and a lower twin contact element. By virtue of the previously described operation, it will be perceived that the upper twin contact elements, mounted on the twin wires 52, are normally separated from the fixed contact elements 24 but that upon operation of the relay these upper contact elements will be brought into contact with the fixed contact elements 24, i. e., the fixed contact elements 24 and the upper contacting elements form so-called make combinations. If the edge of the moving card 30 be straight and parallel with the fixed elements 24, all of the upper moving springs 52 will simultaneously engage all of the fixed elements 24. However, in some uses of the relay it may be found to be desirable for selected ones of the uppermost springs 52 to engage the fixed contact elements 24 at earlier or later times than others of those upper springs 52 engage others of those fixed contact elements 24. If a slight depression such as 4| (Fig. 3) is made in the upper edge 35 of card 30, the springs 52A which engage that slight depression will obviously make contact with their associated fixed elements 24 at an earlier point in the course of the downward movement of armature II than will others of the moving springs 52. These contacts may be labeled early make contacts. Further, if an even deeper depression 42 be made in the edge 35 of the moving card 30, the springs 52B engaging that deeper depression will make contact not only prior to the time at which the normal springs 52 make contact with their associated fixed elements 24, but als prior to the time at which the early make contacts 52A engage their fixed elements 24. This latter group of springs 523 may be labeled preliminary make contacts.

It will also be perceived that by virtue of the above-described operation of the relay, the lower movable spring elements 50 are normally in contact with their associated fixed contacts 24 and that upon the operation of the relay and the consequent downward movement of armature I and moving card 30, this lower layer of springs 50 will break contact with their associated fixed elements 24. By providing similar discontinuities (not shown) in the surface 35 of the moving card 33, early break contacts and preliminary break contacts may also be provided. Conversely in both the case of make and break contacts, if the surface 35 or 36 of the card 30 be provided with areas which project upwardly or downwardly from the surfaces 35 or 35, respectively, late make contacts and late break contacts may also be provided. However, three stages of make-contact and three stages of breakcontact operation are sufiicient for substantially all circuit requirements.

Assuming that each upper set of twin springs 52 may be of the normal, early or preliminary type, and that each lower set of twin contact springs 53 may also be either normal, early or preliminary, it is possible to provide for any one of fifteen different possible contact arrangements for each set of contacts. Thus, by omitting the set of lower springs 50 there may be provided a normal make contact set, an early make contact set or a preliminary make contact set. Similarly, by omitting the upper pair of twin springs 52, a normal, an early, or a preliminary break contact set may be provided. By using both the upper set of twin springs 52 and the lower set of twin springs 5!! in conjunction with the fixed contact element 24, and by selecting whether each of the upper sets and lower sets be normal, early, or preliminary, the following combinations of contact operation may, in an obvious manner, be obtained: A breakmake combination in which both the upper and lower sets are either normal, ear1yorpreliminary; an early make-break, or a preliminary make-early break. or a preliminary makebreak combination, all normally called continuities, in which the upper set of twin wire contacts engages the fixed contact element 24 either somewhat before or substantially before the time that the lower set of contacts separates from the fixed contact elements 24; and an early makebreak, or a preliminary break-early make, or a preliminary break-make combination, all normally called transfers, in which the lower set of twin wire contacts 50 separates from the fixed contact 24 either somewhat before or substantially before the upper set of twin wire contacts 52 engages the fixed contact element 24. Similarly,

there may be early make-early break or preliminary make-preliminary break combinations.

These diverse combinations may be obtained primarily by the coding of the moving card 30, i. e., by the configuration of the surfaces 35 and 36 of that card. If only make contact com-- binations or only break contact combinations are required, obviously either the surfaces 35 and 35 of the card 30 must be so conformed that the springs never make contact or never break contact, or else, more economically, one or more sets of springs 52 or 50 may be omitted or the contact elements may be removed therefrom.

It will be seen that the possible combinations may be extended concatenatiously by strapping the terminals of adjacent groups of contacts in the well-known fashion, whereby a plurality of complex combinations such as make-before break-before-make may be obtained if circuit conditions require.

Referring again to Figs. 1 and 2 of the draw-- ings, it will be noted that the armature I I is subjected to a plurality of forces. The spring 9 exerts a force tending to maintain the armature in its unoperated position, as shown in the drawings. The electromagnetic flux tends to move the armature downwardly to bridge the core legs I, 2 and 3. The moving card 30 exerts a downward force on the armature due to the fact that the moving springs 52 are pretensioned downwardly and consequently exert a force on moving card 30 in a downward direction. Balancing spring I6, which is connected to moving card 30, serves to exert an upward force on card 35 and, therefore, an upward force on armature I I ward force exerted by spring I6 is selected substantially to counterbalance the force exerted by the moving springs 52 and consequently the force exerted by balancing spring It must be varied in accordance with the degree of pretensioning of the springs 52 and the number of springs 52 which are provided.

In special uses of the relay, it may be desirable to have an additional force exerted on the armature tending to restore that armature to normal. If such force be required however, it is normally disadvantageous to have that force continually exerted inasmuch as such force would. also oppose the movement of the armature during its operation. Buffer spring 55 is operative to exert a force to assist restoration of the armature to normal but does not impede the downward movement of the armature until after all contact operations have been completed. Buffer spring 55 is essentially U-shaped, having a crosspiece 56 and two legs 51. A projection 58 (Fig. 2) extends upwardly from the cross-piece 56 and engages the lower edge of the middle core leg 2. The extreme ends of the legs 51 of spring 55 press against the lower surfaces of the outer core legs I and 3, and at a point on the buffer spring 55 intermediate the projection 53 and the extreme ends of the spring legs 51, the spring legs 51 engage projections on the spoolhead 6. The projections on the spoolhead B are so located that the legs 51 of the buffer spring 55 are slightly deformed when the buffer spring is in position on the relay, and the resulting tension of the spring legs 51 serves to retain the buffer spring 55 in position. An additional upstanding per- The uption 59 is provided on cross-piece 56. This portion 59 is so located that the lower edge of the moving card 30 will contact it when the relay is operated. Consequently, just prior to the completion of the operation of armature I I, the moving card 30 will engage the buffer spring and bend it downwardly. When the coil 5 is deenergized the buffer spring 55 will be effective to exert an additional upward force to assist the return of the armature II to normal.

While the use of twin contact elements mating with. single contact elements substantially obviates the possibility of malfunctioning of the relay in the presence of dust or other impurities, a contact cover may be provided further to insure proper operation and also to prevent damage through mishandling. This cover is arranged to engage the front molded block 23 on all four sides to create a substantially dust-tight enclosure for the contacts. It will be noted that since the contact cover 50 engages the upper extremes of the projections 43 and the lower extremes of the projec tions it on the front molded block 23, the contact cover also serves to insure that the springs 52 and 56 will be trapped in their proper positions and yet that, upon removal of the contacts, the springs 52 and 50 may be readily displaced so that the moving card 35 may be removed and a card of different surface configuration inserted for coding purposes.

The embodiment of the invention disclosed in Figs. 4 to 6 is quite similar for the most part to the embodiment shown in Figs. 1 to 3. Consequently, except as to the differences in construction, the details of the embodiment shown in Figs. 4 and 6 will be described in a somewhat less detailed manner.

A plurality of molded insulating blocks I03 to IM are firmly interassociated by a clamping member I53. A core member having three legs I33, Ill} and III is clamped between insulating blocks its and E05, and an energizing coil H2 is mounted upon the center core leg H0. The terminals of the windings of coil II2 are connected to wires H3 which extend through apertures in insulating block I03. A lowermost set of twin wire movable contact springs H4 is molded in and extends through insulating block Hi5 and an upper set of twin wire contact springs H5 is molded in and extends through insulating block I01. A multifingered balancing spring I20 is clamped between the upper molded insulating block I0? and the upper portion of clamp I08. The several elements contained by clamp I08, including the balancing spring I20, the core and the molded insulating blocks I03 to I01, may have matching projections and indentations to assure permanency of registration.

A U-shaped armature I2! is mounted so that the rearwardmost tips of the legs of armature I2I engage the outer legs I09 and III about the core. A spring member I22 engages each of the legs of armature I2I and is clamped between the core and the fixed insulating block I05 in such a fashion that it hinges the armature I2I to the core.

The unoperated position of armature I2I is established by a back-stop element I23 on the core plate I24, a projection I25 at the front of the armature passing through an aperture in the core plate I24 so as to be engageable with the back-stop projection I23.

The fixed contact elements I30 comprise blocks of metal faced at their upper and lower surfaces with precious or semi-precious metal contacting surfaces. These fixed contact elements I 33 are welded or otherwise afiixed to vertically extending wires I3I. As may best be seen in Fig. 5, these wires I3I are molded or otherwise afiixed in a frame-like front molded member I32, extend downwardly, are molded or otherwise affixed in a front retaining element I33 of insulating material and then extend rearwardly and are molded or otherwise aflixed in insulating block I03. The front retaining element I33 is provided with projections I34-which engage extensions I 35 oncore plate I24. Since apertures in core plate I24 firmly engage and position the front ends of the core legs I09 130' III, the core plate is integral with the core. Therefore, since the front retaining element I33 is integral with the core plate I24, element I33 is also integral with the core. In this manner the wire springs I3I are firmly fixed in position.

As maybest be seen in Fig. 6 of the drawings, the front molded member I32 is frame-like in appearance being provided with two horizontal crosspieces I40 and MI joined by two vertical side pieces I42. The fixed, single wire springs I3I are molded in both the lower .and upper crosspieces I40 and I II and extend parallel to the side members I42. The moving twin wire springs I I4 and H extend through individual apertures defined by the lower horizontal member I or the upper horizontal member I40 respectively, of the front molded member I32, by the fixed contact elements I and by the vertical spring wires I3I. It is obviously imperative that the twin contact springs H4 and II5 not engage the wires I3I since such engagement would constitute an erroneous circuit closure. Therefore, horizontal portions I45! and MI are provided with projecting cylinders of insulating material I45 which surround the fixed wires I3I over that portion of their lengths between the fixed contact elements I30 and the upper or lower horizontal members I or I4I. Therefore, the vertical cylindrical projections I of the front molded member I32 serve to guide the twin wire springs H4 and II 5 during their movement. 7

The movement of the twin wire moving springs II 4 and H5 is further controlled by a moving card I 47 which engages projections I48 (Fig. 6) of armature I2I so as to be controlled by the movement of the armature. the extreme upper edge of the moving card I41 engage the outermost fingers I5I and I52 of the balancing spring 0 I20 whereby the card I4! is maintained in proper position and is biased upwardly to assist the armature I2I to restore to its normal position. The centermost fingers I53 and I54 of the balancing spring I20 are pretensioned oppositely to the outermost fingers I5I and I52, i. e., are pretensioned downwardly. The innermost fingers I53 and I54 engage projections I55 on the upper edge of the front molded member I32 so as to assist in fixing the position of member I32.

It will be seen from the above description that upon the energization of coil II2 armature I2I will be attracted downwardly into engagement with the core whereby moving card I41 will also be moved downwardly. Since the upper set of springs I I5 is pretensioned so as to tend to move downwardly, and since the lower set of twin springs H4 is pretensioned so as to tend to move upwardly into engagement with the fixed contact elements I30, upon the downward movement of card I41 the upper twin wire springs I I5 will be permitted to move into contact with the fixed elements I30 and the twin wire springs I I4 will be forced to disengage contact with the fixed contact elements I30. Conversely, upon the de- Projections I50 at I 10 energization of coil H2 and the resultant release of armature I2I, moving card I41 will return upwardly whereby the lower twin wire springs H4 will be permitted to reengage the fixed contact elements I 30 and the upper twin wire springs H5 will be forced to disengage the fixed contact elements I30.

Since the movement of the upper twin wire springs H5 is controlled by the surface I60 (Fig. 6) of the moving card I i? and since the movement of the lower twin wire springs H4 is controlled by the configuration of surface I 6| of moving card Ml, coding of the relay may be accomplished in a manner similar to that previously described with reference to the embodiment depicted in Figs. 1 to 3 of the drawings, that is, the surface IE5 or I5I contacting any given pair of twin wire springs may be elevated or depressed to control the time at which that pair of springs will make or break. contact with the fixed contact element I 30 relative to the time at which the other twin wire contact springs will make or break contact. Consequently, any one group of springs comprising one pair of upper springs H5, one pair of lower springs H4 and one contact element I30 may be arranged to provide any of the aforesaid fifteen or more types of contact combinations including normal, early and preliminary makes and breaks, and the plural variations of transfers and continuity con- It is to be understood that the above-described arrangements are but illustrative of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. In a switching device, a molded block of insulating material, means for fixing said block, a plurality of fixed wire springs molded in said block, contact elements mounted on said fixed wire springs, each of said elements having two faces, a first and a second plurality of movable wire springs, contact surfaces on said first plurali'ty of movable wire springs engageable with one face of said contact elements, contact surfaces on said second plurality of movable wire springs engageable with the other face of said contact elements, and means for controlling the movement of said movable contact springs.

2. In a switching device, a molded block of insulating material, means for fixing said block,

a plurality of fixed wire springs molded in said block, contact elements mounted on said fixed wire springs, each of said elements having two faces, a first and a second plurality of movable wire springs, a plurality of projections on said block engagingsaid movable wire springs, contact surfaces on said first plurality of movable wire springs engageable with one face of said contact elements, contact surfaces on said second plurality of movable wire springs engageable with the other face of said contact elements, and means for controlling the movement of said movable contact springs.

3. In a switching device, a molded block of insulating material, means for fixing said block, a plurality of fixed wire springs molded in said block, contact elements mounted on said fixed wire, springs, each of said elements having two faces, a first and a second plurality of movable wire springs, a plurality of projections on said block extending perpendicularly to said movable wire springs, each of said movable wire springs engaging adjacent ones of said projections, contact surfaces on said first plurality of movable wire springs engageable with one face of said contact elements, contact surfaces on said second plurality of movable wire springs engageable with the other face of said contact elements, and means for controlling the movement of said movable contact springs.

4. In a switching device, a molded block of insulating material, means for fixing said block, a plurality of fixed wire springs molded in said block, contact elements mounted on said fixed wire springs, each of said elements having two faces, a first and a second plurality of movable wire springs, contact surfaces on said first plurality of movable wire springs engageable with one face of said contact elements, contact surfaces on said second plurality of movable wire springs engageable with the other face of said contact elements, and an operating card for controlling the movement of said movable wire springs, said first plurality of movable wire springs being pretensioned against said operating card, and said second plurality of movable wire springs being pretensioned against said contact elements.

5. In a switching device, a molded block of insulating material, means for fixing said block, a plurality of fixed wire springs molded in said block, contact elements mounted on said fixed wire springs, each of said elements having two faces, a first and a second plurality of movable wire springs, contact surfaces on said first plurality of movable wire springs engageable with one face of said contact elements, contact surfaces on said second plurality of movable wire springs engageable with the other face of said contact elements, and a vertically movable operating card for controlling the movement of said movable wire springs, said card having an upper surface and a lower surface, said first plurality of movable wire springs being pretensioned downwardly against the upper surface of said card, and said. second plurality of movable wire springs being pretensioned upwardly against said contact elements and being engageable by the lower surface of said card.

6. In a switching device, a molded block of insulating material, means for fixing said block,

a plurality of fixed single wire springs molded in said block, contact elements mounted on said fixed wire springs, each of said elements having two faces, a first and a second plurality of movable twin wire springs, a plurality of projections on said block extending perpendicularly to said movable wire springs, each of said movable wire springsengaging adjacent ones of said projections, contact surfaces on said first plurality of movable wire springs engageable with one face of said contact elements, contact surfaces on said second plurality of movable wire springs engageable with the other face of said contact elements, and a vertically movable operating card for controlling the movement of said movable wire springs, said card having an upper surface and a lower surface, said first plurality of movable wire springs being pretensioned downwardly against the upper surface of said card, and said second plurality of movable wire springs being 1 2 pretensioned upwardly against said contact elements and being engageable by the lower surface of said card.

7. In a switch, a plurality of contact springs, means for controlling the movement of said contact springs, a plurality of contact members extending perpendicularly to said contact springs and engageable therewith, and an element of insulation material molded on said contact members, said element having a first portion lying in a plane above said plurality of contact, springs, a second portion lying in a plane below said plurality of contact springs, a third portion lying in a plane to one side of said plurality of contact springs, and a fourth portion lying in a plane to the other side of said plurality of contact springs.

8. In a switch, a plurality of contact springs, means for controlling the movement of said contact springs, a plurality of contact members extending perpendicularly to said contact springs and engageable therewith, and an apertured frame of insulating material molded on said contact members, said contact springs extending through the aperture in said frame.

9. In a switch, a plurality of contact springs, means for controlling the movement of said contact springs, a plurality of contact members extendin perpendicularly to said contact springs, 21. contact element on each of said contact members extending perpendicularly to both said contact springs and saidcontact members, and an apertured frame of insulating material molded on said contact members, said springs extending through the aperture in said frame and engage able with individual ones of said contact elements.

10. In a switch, a plurality of groups of contact springs, means for controlling the movement of said contact springs, a plurality of contact members extending perpendicularly to said contact springs and engageable therewith, and an apertured frame of insulating material molded on said contact members, individual ones of said groups of contact springs extending through an aperture defined by said frame and by adjacent ones of said contact members.

11. In a switch, a plurality of groups of contact springs, means for controlling the movement of said contact springs, a plurality of contact members extending perpendicularly to said contact springs, a contact element on each of said contact members extending perpendicularly to both said contact springs and said contact members, and an apertured frame of insulating material molded on said contact members, individual ones of said contact springs extending through individual apertures defined by said frame, by adjacent ones of said contact members, and by individual ones of said contact elements.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,647,792 Gent Nov. 1, 1927 2,282,687 Vigren et a1. May 12, 1942 2,312,493 Sengebusch Mar. 2, 1943 2,452,568 Harrison Nov. 2, 1948 2,566,840 Krumreich Sept. 4, 1951

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