US3297850A

US3297850A - Electrical contact assembly

Info

Publication number: US3297850A
Application number: US448984A
Authority: US
Inventors: Jr Robert L Peek; Theodore S Sipos
Original assignee: Northern Electric Co Ltd
Current assignee: Nortel Networks Ltd
Priority date: 1965-04-19
Filing date: 1965-04-19
Publication date: 1967-01-10
Anticipated expiration: 1984-01-10

Description

^ Jan 10, 1967 R. L. PEEK, JR., ETAL 3,297,850

ELECTRICAL CNTACT ASSEMBLY Filed April 19,V 1965l NVENTORS ROBERT L. PEEK JR. THEODORE S. SIPOS AGEA/Ts ,61490627 Qu/19W Jan. 10, 1967 y R. L. PEEK, JR.. ETAL 3,297,850

ELECTRICAL CONTACT ASSEMBLY vFiled April 19, 1965 2 Sheets-Sheet 2 NVENTORS ROBERT l PEEK JR. THEODORE S. SIPOS AGENTS United States Patent O M 3,297,850 ELECTRICAL CONTACT ASSEMBLY Robert L. Peek, Jr., Smithtown, N.Y., and Theodore S. Sipos, Ottawa, Ontario, Canada, assignors to Northern Electric Company Limited, Montreal, Quebec, Canada Filed Apr. 19, 1965, Ser. No. 448,984 Claims. (Cl. 2Mb-166) This invention relates to an electrical contact assembly and is particularly adaptable for use in a sub-assembly of a communications crossbar switch. In the design of present day crossbar switches for communications switching systems, it is important that the switches be as compact and as light as possible. This reduces floor space requirements for mounting the switches and lessens the floor load per unit area.

However, attempts to make such switches more compact have introduced further problems. For example, electrical contacts in the form of thin resilient spring members must be extended to the rear of a crossbar switch to serve as -terminals for connection of wires. These vconnections are conventionally made by soldering techniques. With more compact switches, the terminals of necessity become more fragile and more closely spaced making it diiiicult to solder wires to them. This can be a serious problem when it is recognized that the total cost of a switch is largely dependent on the cost of making the electrical connections.

This problem has led switch designers to look for alternative ways of connecting wires to terminals. One known way that is gaining wide acceptance is the technique of solderless wire wrapping. This is accomplished by wrapping wire around substantially rigid terminals having sharp corners as found in a rectangular cross-sec tion. The spacing of such terminals can be minimized by making the cross-section substantially square. Solderless wire wrapping techniques are known to be less expensive than lsoldering techniques and also to require less working space while making the connections. However, previous attempts to connect rigid terminals to resilient spring members while at the same time accomplishing the ,desired compactness of a switch have not been entirely successful.

We have invented an electrical contact assembly that permits the construction of compact switch assemblies; that permits use of solderless wire wrapping; and that uses a minimum number of parts.

According to our invention, iirst and second elongated electrically conductive contact support members are arranged to be supported at a region intermediate their ends. On end of each member is of relatively thin crosssection for resilience and is arranged to carry an electrical contact. The other end of each member is of relatively thick cross-section for rigiditythe thick cross-section extending from its other end -into the intermediate regi-on. Means are provided for supporting an insulator between the two contact support members in the intermediate region whereby the members are insulated and separated from each other and whereby the one end of the first member is substantially coextensive with the `one end of the second member.

The advantages `of our invention will be more readily apparent by considering its application to a crossbar switch. In .a typical 200 crosspoint six wire crossbar 4 3,297,850 Patented Jan. 10, 1967 ICC switch, there are 20 vertical units, each requiring 60 terminals for the contact carrying resilient spring members. Each of these contact carrying members is adapted to mate with an associated fixed contact carrying member. The fixed members are usually multiplied together and brought out to a common terminal at the back of the switch. It is usual to stack a number of the resilient members and support them in what is cornmonly known as a pile-up. In the past, these members have been separated and insulated from each other by metallic spacers and/or insulators. The sub-assemblies of resilient members were attached to and clamped to the switch frame by insulated screws. Because the contact support member according to our invention, is supported at a region including its thick crosssection, this region serves as the separator and only a thin insulator is required to insulate two members from each other. The extremity of the end of the member that is of relatively thick cross-section can be made rectangular and preferably square or making connections by solderless wire wrapping.

In one embodiment of our invention as applied to a crossbar switch, we employ a sheet carrying a plurality of fixed contacts, one associated with each of the contact support members. This multiple board can be advantageously made of insulating material to serve both as a pile-up insulator and as the xed contact support member, thereby contributing to the compactness `of the final switch assembly and to the reduction of parts.

It has also been common in the past to support and assemble the fixed contact support members independently of the resilient movable contact support members with the fixed contacts being interspersed between the movable contacts. Presumably, this was done to economize on metallic material .and to reduce weight because the fixed Contact support member would otherwise have had to be extended toward the back end of the movable -contact support members to permit a common support. Again, the fixed contacts were supported, separated and insulated from each other by metallic spacers, insulators and insulated screws. The fixed contact support members were supported in the pile-up between adjacent columns of contact pairs thereby using up space between these columns to locate the supporting structure. In contrast, our insulated sheet for carrying the iixed contacts can serve as an insulator between the iixed contacts and the movable contacts, with the complete assembly of fixed and movable contacts being supported in the thick cross-section region of each contact support member. The insulated sheet therefore eliminates all of the support structure for the iixed contacts. ln addition, with the assembly being supported in the thick cross-section region of the support member, the spacing between adjacent contact support members can be reduced to permit construction of a more compact switch.

The iixed contact carrying insulated `sheet can be made lighter than the previously used metal supports there'by realizing a weight saving for the switch.

We have succeeded in making a 200 crosspo-int six wire crossbar switch in accordance with our invention that occupies a volume of only 460 cubic inches compared with 1925 cubic inches of a typical prior art switch with similar capacities. The weight of our switch has been reduced to 15 lbs. compared with 58 lbs. of the typical prior art switch. The back of our switch contains 1520 terminals suitable for wire wrapping in a space measuring 2l inches X 4.4 inches.

While the advantages of our invention 'have been described in connection with a communications crossbar switch, it will be understood by those skilled in the art that the invention is applicable to ot-her mechanisms employing an electrical contact assembly. For example, our invention can be used in the contact assembly of an elec'- romechanical relay.

Preferred embodiments of our invention will now be described, by way of example, with reference to the accompanying drawings in which: v

FIG. 1 is an elevation view of a contact support member representative of the prior art;

FtIG. 2 is an elevation view of a contact support member according to our invention;

FIG. 3 shows an electrical contact assembly according to our invention sui-table for use in ya relay;

IFIG. 4 (shown on the sheet of drawings containing FIG. 6) is an embodiment of our invention as applied -to a vertical sub-assembly of Va crossbar switch;

FIG. (shown on the sheet of drawings containing FIGS. l to 3) is an electrical contact assembly wherein an insulated sheet is used `to support the fixed contacts; and FIG. 6 is an application of the assembly of FIG. 5 to a vertical sub-assembly of a crossbar switch. FIG. 1 shows a typical contact support member of the prior art. Two elongated, electrically conducting resilient contact support members 11, 111a carry

electrical contacts

12, 12a at one end, and are extended at the other end to form terminals |13, 13a for connection of wires byl soldering. The support members 11, 11a are supported, spaced and insulated from each other by means of a metal spacer 14 a :pair of insulators -15 and insulated screws |16. .In some cases, `a single thicker insulator could be used in lieu of the metal spacer. A pair of xed contacts 17, -17a are held in mating position with the

contacts

12, 12a respectively by means not shown. A card .1'8 retains the support members 11, 11a in a position to keep the contacts =12, 12a and ,17, -17a apart and is adapted to move -to `allow the contacts to mate under the influence of spring tension on the support members 11, 11a. If the terminals 13, 13a are closely spaced, soldering becomes difiicult.

FIG. 2 shows the arrangement of FIG. 1 modified according to our invention. Elongated, electrically conductive contact support members 2-1, 21a have one of their ends 22, 22a made of relatively thin cross-section for resilience and are yarranged to carry electrical contacts 23, 23a. The other ends 24, 24a of the members 21, 21a are of relatively thick cross-section for rigidity. The extremity of the ends 24, 24a kare of rectangular and preferably of substantially square cross-section to serve as terminals 25, 25a for connecting wires by solderless wire wrapping. The support members 21, 21a are arranged to be supported in la region intermediate its ends -in the thick cross-section by support means such as insulated screws 2'6. The ythick cross-section region provides rigidity to the assembly and serves to separate the support member 21 from support member 21a. These members are ins-ulated from each other by a single thin insulator 27. The ends 24, 24a are of thicker crosssection where they are supported than at their extremities. The mating of the movable contacts 23, 23a with fixed contacts 28, 28a by means of the card 29 is accomplished in the same manner as in FIG. 1.

The ends 22, 22a can be conveniently formed of pieces of resilient material and the thick cross-section ends 24, 24a can be formed of pieces of rigid material, the pieces thereafter being joined together in overlapping relationpreferably by conventional welding techniques. The support members 21, 21a are adapted to be supported in the overlapped region.

as a make contact assembly for an electro-mechanical relay. Two contact support members 31, 31a of the type shown in FIG. 2 are assembled and supported in their thick cross-section region and insulated by a single insulator 32 such that contacts 33, 33a are normally in separa-ted, mutual face-to-face relation. Contact 33a can be moved to mate with contact 33 by .the action of the card 34 in the well lknown manner. In this case, the support member 31 of the lixed contact 33 may lbe rigid rather than resilient, or be supported at its forward end by a iixed card or -other means not shown.

FIG. 4 shows an embodiment of our invention that is useful in a crossbar switch vertical sub-assembly. A number of contact support members 41 of Ilhe type shown in FIG. 2 are mounted in a row. A number of rows of support members 41` are clamped in a stack or pile-up between metal bars 43 by means of insulated screws 44. Each row of support members 41 is separated from its yadjacent -row of support members in the stack by 'its thick cross-section and an insulator 45. A number of fixed contacts `46 are interposed between the support members 41 and are carried by metal plates l47 which are supported and assembled by insulated screws and spacers 48. The support members `41 can be tensioned so that their contacts 42 will mate with associated fixed contacts V46 upon movement of the cards 49 in the well Iknown manner.

FIG. 5 shows an embodiment of our invention which uses an insulated sheet or multiple board `51 to carry the fixed contacts 52. A pair of contact support members 53 of the type shown in FSIG. y2 are mounted on the board 51 so lthat their contacts 54 are disposed in spaced, face- -to-face relationship with the fixed contacts '52. The extremities of the thick cross-section end of the support members 53 extend beyond the edge of the board 51 to serve as tenminals 55 for connecting wires by wire wrapping.

The fixed contacts 52 are multipled together on the board 51 by a thin metal pattern 56. The pattern 56 is extended toward the edge of the board 51 and is connected to a terminal 57which extends beyond the edge of the board for connecting wires by wire wrapping. The support members 5'3 'and the terminal 517 are supported and assembled to the board 51 by screws 58. :Upon movement of the cards 59 the movable contacts 54 will mate with the Ifixed contacts S2 in the well known manner.

It should ibe noted that the support members 53 are separated from the lixed contacts 52 by their thick cross'- section. The board 51 serves not only as a support member for the fixed contacts 52 but also to insulate them from the support members 53.

FIG. 6 shows a modification of the vertical subassembly of a crossbar switch illustrated in FIG. 4 to incorporate the embodiment of FIG. 5. The arrangement is similar to the one shown in FIG. 4 except that the xed contacts are carried by insulated sheet or multiple board 51 of the type shown in FIG. 5. Now, the pile-up of movable contact support members 41 and the insulated boards 51 can be supported inthe thick cross-section of the members 41. With the elimination of the separate support structure for the fixed contacts (see elements 47 and 48 of FIG. 4), the adjacent support members 41 can be more closely spaced to permit construction of a more compact switch. The boards 51 not only insulate the iixed contacts 52 from the contact support members 41 but also insulate contact support members 41 from each other in the pile-up.

The sub-assemblies of contact support members as illustrated in FIGS. 4 and 6 can be conveniently fabricated by well known techniques. A row of the thin, resilient ends of the contact support members can be punched from a single sheet of metal with thin end connections retained so that the layer of spring contacts can be handled and assembled as a unit. The row of rigid, thick crosssection ends can be punched from a single sheet of metal with end connections retained in a similar Way. The row of resilient and rigid ends can be assembled by welding them together. The end connections can then be sheared off to separate the assembled members electrically and mechanically from each other.

Before shearing off the terminal end members, the spring and terminal sub-assembly can be mounted on the multiple board and secured to it by bonding or other means. After the terminal end connections are sheared off, the resulting sub-assembly comprises one complete set of fixed and moving contacts for a vertical unit. For a six-Wire switch, six of these sub-assemblies are stacked and bolted together to provide the complete contact assembly of a vertical unit.

We have shown that we have invented an electrical contact assembly that is useful for compact switch assemblies; that permits advantageous use of solderless wire wrapping; and that uses a minimum number of parts.

What is claimed is:

1. An electrical contact assembly comprising:

(a) first and second elongated, electrically conductive contact support members, one end of each said member carrying an electrical contact `and being of relatively thin cross-section for resilience, the other end of each said member being of relatively thick crosssection for rigidity, the thick cross-section of each said member extending from its other end into a region intermediate its ends;

(b) and insulator;

(c) and support means supporting the insulator between the two said members in said intermediate region, whereby said members are insulated and separated from each other, and whereby the one end of said first member is substantially coextensive with the one end of said second member.

2. An electrical contact assembly as defined in claim 1 wherein the extremity of the other end of each said member is of substantially square cross section, and the other end of each said member is of greater cross section in said intermediate region than at its extremity.

3. An electrical contact assembly as defined in claim 2 wherein the one end of each said member is formed of a piece of resilient material and the other end of each said member is formed of a piece of rigid material, the two pieces of each said member joined in overlapping relationship, and wherein the support means is applied across the overlap of the two pieces of each said member, and wherein the insulator is disposed between the piece of resilient material of said first member and the piece of rigid material of said second member.

4. An electrical contact assembly comprising:

(a) a plurality of elongated, electrically conductive contact support members, one end of each said member carrying an electrical contact and being of relatively thin cross-section for resilience, the other end of each said member being of relatively thick crosssection for rigidity, the thick cross-section of each said member extending from its other end into a region intermediate its ends;

(b) a plurality of insulators;

(c) support means supporting all said members in said intermediate region of each said member into a stack with an insulator interposed between each adjacent said member, whereby said members are insulated and separated from each other, and whereby the one end of all said members are substantially coextensive, with all contacts facing in the same direction;

(d) and a plurality of electrically conductive fixedcontact carrying members one associated with each said support member, said fixed members supported independently of said support members `and disposed in a stack whereby their individual contacts are each in a separated, face-to-face relationship with an individual contact of an associated said support member.

5. An electrical contact assembly as defined in claim 4 wherein the extremity of the other end of each said support member is of substantially square cross section, and the other end of each said support member is of greater cross section in said intermediate region than at its extremity.

6. An electrical contact assembly as defined in claim 5 wherein the one end of each said support member is formed of a piece of resilient material and the other end of each said support member is formed of a piece of rigid material, the two pieces of each member joined in overlapping relation, wherein the support means is applied across the overlap of the two pieces of each member and wherein each insulator is disposed between the piece of resilient material of one said support member and the piece of rigid material of an adjacent said support member.

7. An electrical contact assembly comprising:

(a) a plurality of electrical contact assemblies as defined in claim 6;

(b) and support means supporting said assemblies in a spaced-apart row whereby the individual said support members at each level of their stacks are disposed in the same plane with their one ends being substantially coextensive, and whereby the individual said fixed members at each level of their stacks are disposed in the same plane.

8. An electrical contact assembly as defined in claim 7 wherein said assembly is part of the vertical assembly of a crossbar switch.

9. An electrical contact assembly comprising:

(b) a sheet carrying a row of electrical contacts on one side thereof, one contact associated with each said member;

(c) and support means supporting each said member in said intermediate region against the sheet whereby each contact of the sheet is insulated from said members and is disposed in face-to-face relationship with the contact of its associated said member.

10. An electrical contact `assembly as defined in claim 9 wherein the sheet is an insulated sheet and serves to insulate each contact of the sheet from said members.

11. An electrical contact assembly as defined in claim 10 including a thin metal pattern attached to the sheet, the row of electrical contacts carried by said pattern.

12. An electrical contact rassembly as detined in claim 11 wherein the extremity of the other end of each said member is of substantially square cross-section, and the other end of each said member is of greater cross-section in said intermediate region than at its extremity.

13. An electrical contact assembly as defined in claim 12 wherein one end of each said member is formed of a piece of resilient material `and the other end of each said member is formed of a piece of rigid material, the two pieces of each said member joined in overlapping relation, and wherein the support means is applied across the overlap of the two pieces of each said member.

14. An electrical contact assembly comprising:

(a) a plurality of electrical contact assemblies as defined in claim 13;

(b) and support means supporting said assemblies in said intermediate region of each said member into a stack of assemblies with the other side of the sheet of one said assembly mounted against the individual said members of an adjacent said assembly, whereby said members on-the one said assembly are insulated and separated from said members on the adjacent said assembly. v 15. An electrical contact assembly as dened in claim 14 wherein said assembly is part of the vertical assembly of a cross'bar switch, and each of the contacts carried by the pattern are multiplied together and connected to 10 a terminal.

- References Cited by the Examiner UNITED STATES PATENTS Mason 339-267 X Buhrendorf 174-94 Ayer 174-88 Derkas 174-94 X Ruckriegel et al. 200-166 X

Claims

1. AN ELECTRICAL CONTACT ASSEMBLY COMPRISING: (A) FIRST AND SECOND ELONGATED, ELECTRICALLY CONDUCTIVE CONTACT SUPPORT MEMBERS, ONE END OF EACH SAID MEMBER CARRYING AN ELECTRICAL CONTACT AND BEING OF RELATIVELY THIN CROSS-SECTION FOR RESILIENCE, THE OTHER END OF EACH SAID MEMBER BEING OF RELATIVELY THICK CROSSSECTION FOR RIGIDITY, THE THICK CROSS-SECTION OF EACH SAID MEMBER EXTENDING FROM ITS OTHER END INTO A REGION INTERMEDIATE ITS ENDS; (B) AND INSULATOR; (C) AND SUPPORT MEANS SUPPORTING THE INSULATOR BETWEEN THE TWO SAID MEMBERS IN SAID INTERMEDIATE REGION, WHEREBY SAID MEMBERS ARE INSULATED AND SEPARATED FROM EACH OTHER, AND WHEREBY THE ONE END OF SAID FIRST MEMBER IS SUBSTANTIALLY COEXTENSIVE WITH THE ONE END OF SAID SECOND MEMBER.