US2502438A - Selector switch - Google Patents

Description

G. DEAKIN SELECTOR SWITCH April 4,' 1950 4 Sheets-Sheet 1 Filed Feb. a, 1945 IN VEN TOR. GER/1 4 0 DEA KIN A TTOR/X)? a 7 8 kW 1 April 4, 1950 G. DEAKIN SELECTOR swI ca 4 Shets-Shet 2 Filed Feb. 8, 1945 April 1950 G. DEAKIN 2,502,438

SELECTOR swnca Filed Feb. 8, 1945 4 Sheets-Sheet 3 III-IIIIIII LJ LT P INVLNTOR.

@ERA L0 DEA K/N A TTORNE X G. DEAKIN SELECTOR SWITCH April 4, 1950 4 Sheets-Sheet 4 Filed Feb. 8, 1945 I N VEN TOR. GERAL 0 DEA K//\/ A r Tom/5r x k k \\\E Patented Apr. 4, 1950 UNITED STATES PATENT OFFICE SELECTOR SWITCH Application February 8, 1945, Serial No. 576,797

9 Claims.

The present invention relates to selector switches of the'type as used in telecommunications systems as for example, automatic and semi-automatic telephone exchange systems and the like. The switching structure of the invention is designed to produce a switch of durable construction adapted to economical manufacture incident to the requirement of a reduced number of parts and wherein the parts are of simplified form. It is further of a design and arrangement facilitating the assembling and removal of the parts for inspection and repair and which, moreover, will operate more satisfactorily over long periods of service with a minimum of maintenance requirement.

A further object of the invention is to provide a design and structural arrangement of the brush unit of a selector switch capable of being moved at high speeds over a line of terminal pins with a minimum of vibration. It is, moreover, designed to make effective contact between the brushes and the terminal pins so as to establish good electrical connection for a maximum period and with reduced danger of short-circuiting adjacent pins or of damage either to the pins or to the brushes incident to conditions of permissible tolerances caused by Wear after long periods of use. The features thereof are further desirably embodied in a switch structure designed for spreading the contact brushes to convert from rubbing or circuit closing to a non-rubbing or open circuit position at the end of each travel movement of the carriage thereby to be applicable to a flat type of switch having two sets of brushes which are traversed over a terminal bank with a linear reciprocal movement and wherein one and a different set of brushes make rubbing contact With bank terminals in each direction of movement.

A further object is to provide a brush contact switch structure incorporating a simplified and.

advantageous arrangement to effect spreading of the contact brushes wherein shifting or spreading bars are employed and movably supported to have direct shifting engagement with the brush springs responsive to movement of the carriage and with pressure application co-linear or parallel to the carriage movement thereby to.

To contribute to springs is provided for in a manner whereby they will permit of the spreading action in non-interfering relation to the springs of an adjacent brush. This latter feature is further employed in conjunction with a brush guide member associated with the brush contacts and extended for multiple terminal pin engagement. To further maintain the alignment, reduce vibration and effect more uniform wear distribution in a multiple brush contact structure, it is provided that the brushes shall be operated in sets of alternatelyarranged brushes extending to each side of the central vertical axis of the brush carriage. This balances the resultant pressures of brush engagement thus to balance or reduce side pressures on the carriage support.

The foregoing and other advantages of the present improvements will be more fully understood by reference to the accompanying drawing wherein like reference characters are applied to the corresponding parts in the several views.

In the drawings,

Fig. l is a view in front elevation of a brush carriage constructed to embody the features of the invention;

Fig. 2 is an enlarged partial vertical crosssectional view taken at right angles to Fig. 1 and on line 2-2 of Fig. 1;

Fig. 3 is an enlarged sectional view taken in a horizontal plane on line 3-3 of Fig. 1;

Fig. 4 is a similar view taken on line 4-4 of i 1;

Fig. 5 is a development illustrating the respective brush positions and showing the brush ends in horizontal section and wherein the positions are respectively those of brush engagement and intermediate and spread positions of non-engagement; Q

Fig. 6 is a bottomplan'view of the brush guide.

In the preferred embodiment of the invention as disclosed, the features thereof are incorporated in a flat type selector switch of the kind in which the brush carriage is driven to have a reciprocal, rectilinear movement by a rotary drive member provided'with a continuous thread or worm groove drive. In this disclosure there is shown a brush carriage assembly of a multiple brush type comprising eight brushes.

In the switch structure resilient brush springs I having contact portions or brushes 2 at their lowermost free ends are formed as an integral part of a brush unit including an attaching portion 3 secured by rivets 4 to an insulating fiber supporting strip 5 supported by a driving carriage, and horizontally disposed contacts or spring portions 6 are formed on the upper end of the brush unit and positioned in engagement with a conductor feed bar I. The latter is positioned above and in parallel relation to a. row of bank contacts with which the brushes engage. The lower ends or brush contacts of the springs I, as best shown in Fig. 5, have inwardly deformed contact end portions having flared entry formation and are positioned to wipe over the contact pins 8 of a contact bank. The pins 8 are made of a hard metal, such as Phosphor bronze and are positioned in suitably spaced relation parallel to the paths of movement of the brushes as determined by the operation of the supporting carriage. Each brush unit as shown comprises a pair of opposed spring'e lements to engage opposite sides of the contact'pins.

The carriage or travelling support for the brush units, as illustrated best in Figs. 1 and 2, is composed of the opposite end frame plates 9 extending transversely of the ban and formed at their forward and rearward ends with sun gularly disposed and upwardly extending supporting flanges. These flanges are rigidly secured to slide bearing member In having slide bearing engagement; on the parallel and fixed guide rods 1 I supported parallel to the terminal rows for the guiding of the carriage movement in parallel relation thereto-. Toj impart the reciprocal travel motion to the carriage, the latter has supported thereon, upon centrally positioned bearing portion. l2, aswiveled, elongated and tapered end shoe l3 which fits into the reversing spiral; feed groove I d, formed in suitably driven roller Ii; The roller is journalled to extend parallel to the path or movement of the carriage. The operation thereof, on uni-direc# ti'onal rotation of the feed roller is to impart to the carriage a reciprocating motion for traversing the spring brushes over the respective rows of contactsin the manner well Understood. The oppositely positioned frame plates 9 as best shown. in Fig. 2 are slotted to; receive reduced and shouldered end portions of the brush sup porting strips 5 and are clamped by means of; upper and lower longitudinally extending bolts H and i8 haying the securing nuts l9 threaded thereon. assembling of the brush units within the carriage by simply inserting off the end portipns r within t e slots and securing the assembly by means of the clamping bolts referred to.

As disclosed, the brush. carriage is constructed toaccommodate eightbrush' unitseach of which cooperates with a row of terminal pins. These brush, units are arranged to be operable in two sets of four units, each arranged to be similarlyv but reversely operated in the desirable arrangement as, herein provided in. alternating relation and whereby. in their order of operation, they will be successively in open and closed orre versed position-from front to rear of the carriage. Thus, by their order of. operation, there is obtained. a balanced or uniform, distribution of the pressures on the carriage incident to the successive engagementwith the pins, thereby to avoid unbalanced. pressures such asmight cause vibrations under conditions of wear.

The arrangement provided is such that the respective sets of the brushes shall be alternately controlled or operated in a manner whereby when the carriage is traversed in. one direction, one set of brushes will make circuit closing. or rubbing contact with the terminal pins while the other set is retained. in non-engaging or open This provision permits; of convenient circuit position and provision is made for automatically reversing the operating relation at the end of each traverse of the carriage. This is accomplished by the spreading of the brush contact end portions of one set of brushes throughout one direction of the travelling movement with a similar spreading of the brushes of the other set in the opposite direction of the travel movement. The structural provision therefor includes an arrangement of spreader bars 20 associated with each of the brush units with the spreader bars interposed between the brush springs and slidable in bearing apertures 21 in the frame plates 9. These bars are positioned parallel to the path of movement and have reduced opposite end extensions projecting beyond the frame plates for engagement at the end of each travel. movement with stationary abutments 2 mounted on the selector frame and thereby eifective to shift the bar to first in one direction and then in the other.

In accordance with a feature of the present invention the spreading of the brush contacts is effected by a direct camming engagement between a portion of the spreader bars 20 and the brush springs I.. To be so effective the brush springs are formed with inclined surface or camming shoulders 23 formed by inwardly deforming or pressing the spring metal into channel formation and of a configuration to provide, theinward shoulders with opposite inclination as, best shown in Fig. 4 whereby upon being engaged by a portion of the spreader bars the camming. action will; effect the required spreading of the brushes for open circuit or non-rubbing position. In the structure as shown the engagement is effected by meansoof depending lugs 24 of the spreader bars 20 positioned in horizontal alignment with the camming shoulders 23 on the springs I. These lugs are of a length and are positioned to determine bymeans of the stop engagement at the extremity of the carriage travel that they shall assume positions of non-engagement or spaced relation to the camming surfaces in one position and in the other position shall: be retained. in the interposed spreading position under resilient pressure of the springs I thereby to retain. the brushes in their spread relation throughout one direction of travel.

As best shown in Figs. 1 and 2, the camming shoulders 23 are vertically elongated for a sub" stantial distance and are engaged by a vertical shoulder or edge surface of the lug 24. from which the advantage is obtained that, incident to the vertical line of engagement under the relative rectilinear movementof the parts, a tendency to the setting up of a vertical deflecting force is to a substantial degree counteracted. As a result there is a reduced tendency to vibration of the carriage in consequence of vertical pressure components upon the successive engagement of the multiple spring contacts. Also, as will be noted in Fig. 1, the spring elements I are r-einforced in the lateral direction by a progressive increase in their width from apoint approximately. in the plane of the lower end of the camming shoulders 23 thereby to add rigidity thereto.

Associated with each of the brush units there is provided a brush guide member 25 supported by the lower end portions of the frame members 9 by means of reduced end portions of, the guides fitting slots in the frame member and clamped.

in position by means of the bolts I1, IS. The central portion of the guide member is formed with a downwardly extended guide portion. 216

. 5 formed with a longitudinally extending guide slot 27 extending the full length of the guide portion and formed outwardly flared at its lower edges and also with the ends of the slot 21 flared in order to guide the pins 8 into the slot as the uide moves over the terminal bank thereby at all times accurately positioning the brush contacts engaging therewith with relation to the pins. The guide members are interposed between the coacting brushes to be engaged thereby within slots 28 formed in the guide 25 to determine a thickness proportioned to limit the inward movement of the brush contacts so that their contact portions 2 are in slightly spaced relation when in a position between a pair of the pins 8 as indicated in connection with the centre brush of Fig. 5. The employment of the guides accordingly establishes a slight separation of the brushes between pins contributing to more accurate entry of the terminal pins therebetween particularly in the instance of a pin which may have become deflected in its position. In addition to maintaining the proper alignment of the brush ends with relation to the pins the use of the guides reduces vibration during the travel movement of the carriage and permits a maximum period of rubbing contact which in practice may be approximately 85% of the distance between the pin centers. The employed arrangement of brush guide is of particular advantage in the maintaining of the proper alignment in the case of unequal tension of the brush springs in that the brush having the greater tension might otherwise force its way through the space between the pins and short circuit adjacent pins.

Further in accordance with the present improvements and as best shown in Figs. 1 and 4, the alternated brushes are positioned at opposite sides of the central vertical axis of the carriage and toward the forward portion of the carriage considered with relation to the circuit closing direction of travel. This offset arrangement of the alternate brushes permits of a more compact assembled structure in that closer spacing is permitted without interference of the brushes in their spread positions. It further follows that the engagement of the brush springs with the sides of the guide member in positions between terminal pins will exert a resilient force upon the guide members in a manner operating to suppress tendency to vibration in a horizontal plane.

.The structural arrangement as described provides for alternating of the circuit closing contact engagements in an improved and balanced manner with an arrangement for brush separation which maintains effective and accurate alignment throughout long periods of use. It further and to a substantial degree eliminates vibration incident to the improved manner of brush operation, the rectilinear and direct engagement between the spreader bars and brush springs, the provision of elongated vertical camming surfaces and the ofiset relation of the brush springs relative to the central vertical axis of the carriage.

In the assembling of the structure as will be appreciated a particular advantage as related to maintenance is present by reason of the described structure permitting separate and unit assembly of the frame plates, brush supports. spreader bars and guides retained as a unit by the clamping bolts. The assembled unit is then attached by means of the securing screws to the carriage support in which operation the oppositely extended contact springs 6 are slipped over the feeder bars 1 into their operating position.

While I have described my invention as applied 1 to a flat type selector switch, it will be understood that it is equally applicable to many other types of switches. Moreover, many modifications as will be apparent may be made therein without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

l. A selector switch comprising a terminal bank, a row of contact terminals thereon, a brush carriage, means for moving the carriage back and forth over the bank, a brush spreader bar shiftable with respect to the path of carriage travel, a brush unit mounted on the carriage formed for camming engagement with the spreader bar and responsive to movement of the bar to effect shifting of thebrush responsive to movement of the bar into engaging and non-engaging position relative to the contact terminals and actuating means operative to effect the movement of the spreader bar at the end of each traverse of the carriage.

2. A selector switch comprising a terminal bank, a row of contact terminals projecting from said bank, a brush carriage, means for moving said brush carriage over said bank, a brush having a contacting surface for making engagement with the terminals, and a shiftable brush deflecting member supported by the carriage to be shiftable relative thereto, said deflecting member being positioned for direct engagement with the brush to effect deflection thereof into nonrubbing circuit position with respect to said terminals.

3. A selector switch. comprising a terminal bank, rows of contact terminals thereon, a brush carriage, means for moving the carriage back and forth over the bank, brush deflecting members and brush springs mounted on the carriage for relative rectilinear movement with respect to the path of carriage movement and formed for camming engagement to effect shifting of the brush springs responsive to said movement into engaging and nonengaging posit on relative to the contact terminals, and actuating means operative to eiiect the relative movement of the brush springs and deflecting members in reverse operation at the end of each traverse of the carriage and in sets of alternately positioned brush springs.

4. A brush unit for a selector switch comprising a brush carriage member, a pair of end plates secured to said brush carriage member, a plurality of brush supports of insulating material, brush springs mounted on the supports, spreader bars fitted to bearing openings in the end plates and formed for limited sliding movement therein and positioned for spreading engagement with the springs and means for clamping said brush sup ports between said end plates and retaining said spreader bars in the operating assembly.

5. A brush unit for a selector switch comprising a brush carriage member, a pair of end plates secured to said brush carriage member, a plurality of brush supports of insulating material, brush springs mounted on the supports, spreader bars fitted to bearing openings in the end plates and formed to limitsliding movement therein and. having spreading engagement with the springs, guide members engaged by the brush springs, said brush supports and guide members having interlocking engagement with openings in the end plates and means for clamping said brush supports and guide members between said end plates and securing the spreader bars in operating position.

6. A selector switch comprising a terminal bank, arow ,oicontact terminals thereon, a brush engageable with said terminals, means ior guidingsaid brush back and forth over the bank, and means including a brush spreader bar to effect shifting of the brush from engaging .to nonengaging position in relation to said contact terminals.

7. A switch as defined in claim 6, wherein the brush guiding means includes a brush carriage, and the brush shifting means includes a member mounted on said carriage in osition for camming engagement with said spreader bar, whereby the relative motion therebetween produces the described brush shifting action.

'8. In combination with a plurality of rows of terminal contacts, abrush carriage movable back and forth "in a straight line whose length corresponds to the length of said contact rows, said carriage including a plurality of brushes, means for causing one of said brushes to engage the contacts of one of said rows in one direction only, and means for causing another of said brushes to engage the contacts of another of said .rows in the opposite direction only.

9. A switch unit for a-t'erminal bank comprising a plurality of brushes moveablealongsaid'tere REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date Number Name 1,126,727 Dietl -1. Feb. 2, 1915 2,225,646 Lewis Dec. 24, .1940

FOREIGN PATENTS Number Country Date 111,492 Australia Sept. 6, 1939

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