US2577225A - Rotary switch - Google Patents

Description

Dec. 4, 1951 L. G. BARRY 2,577,225

ROTARY SWITCH Filed Sept. 22, 1949 2 Sl-IEETS-SI'iEET l .lllllll Z9 INVENTOR Mywf @fd 2km ATTORNEY Dec. 4, 1951 1 @.BARRY 2,577,225

ROTARY SWITCH Filed sept. 22, 1949 2 SHEETS-SHEET 2 Uli!i ZZ ATTORNEY Patented 4, 1951 UNITED STATES PATENT OFFICE ROTABY SWITCH Leon G. Barry, Whippany, N. J., assigner to United States Instrument Corporation, Summit, N. J., l. corporation of New Jersey Application September 22, 1949, Serial No. 117,226

(Cl. o-11) 7 Claims.

This invention relates to rotary electric switches and more particularly to multiple throw switches, or those adapted to control a plurality of circuits, especially circuits carrying substantial loads. Accordingly, it is a general object of the present invention to provide a .multiple-throw rotary switch having cooperating contacts which are designed to carry substantial electrical loads with a minimum of contact resistance.

A further object is the provision of a switch comprising a plurality of decks or switch assemblies operated by a common shaft and associated with a single indexing mechanism. Another object is the provision of a switch of the character described, each switch assembly or deck comprising a stator, rotor, and backing plate, the several parts being so designed and constructed that the stator, fixed contacts, and rotor are interlocked when assembled, and are positively prevented from disengagement when the backing plate is secured to the stator.

A further object is the provision of a switch of the character described. in which the stator, having provision for eight or more fixed contacts and associated terminals, is provided with peripheral projections between adjacent contacts to increase the length of the leakage paths therebetween.

A further object is the provision of such a switch in which the fixed contacts are generally of U-shape, their legs extending radially inward on opposite faces of the stator and embracing a portion of the annularstator therebetween, the,

inner end portions of the said legs extending inwardly of the inner periphery of the stator and being deformed toward each other so as to t over the stator with a snap action. Preferably, the said contact legs t in shallow grooves formed in the respective faces of the stator to prevent their displacement circumferentialiy thereof. their displacement radially of the stator being prevented by the aforesaid snapaction.

e A further object is the provision of a switch of the character described. in which the multiple contacts carried by the rotor comprise one or more blades on one face of the rotor and a corresponding number of blades carried on the opposite face of the rotorcorresponding blades being secured together by rivets passing through the rotor and forming a good electrical contact between the said blades. Still another object is the provision. between corresponding blades on opposite faces of the rotor, of a small 'spring acting between the wiping portions of said corresponding blades and tending to force them apart, insuring good electrical contact between the respective blades of each pair and the fixed contacts of the stator.

Another object is the provision of a switch of the type in question, comprising multiple units or assemblies the rotors of which are centrally apertured to receive a common operating shaft, each rotor being provided with a projection or lug on one face and a corresponding recess on the opposite face. so that when the plurality of rotors are assembled on the common shaft, they will be `in correct alignment as respects corresponding contacts of the several switch assemblies.

Other and further objects, features and advantages will be apparent from the description which follows, read in connection with the accompanying drawings in which:

Figure 1 is a side view partly in section and partly in elevation, illustrating a multiple-throw rotary switch, according to the present invention;

Figure 2 is a vertical transverse section on line 2-2 of Figure 1;

Figure 3 is an end elevation of the aligned switch decks or assemblies;

Figure 4 is a partial section on line l--l of Fig ure 3 illustrating one switch assembly and a portion of the adjacent switch assembly;

Figure 5 is an exploded view of a switch assembly (without contacts) Figure 6 is an exploded view of a stator contact and associated terminal; and

Figure 7 is a view of a contact blade.

In order to facilitate an understanding of the invention, reference is made to the embodiment thereof shown in the accompanying drawings and detailed descriptive language is employed. It will nevertheless be understood that no limita tion of the invention is thereby intended and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.

Referring to Figure l the switch in general comprises a base plate I0, face plate il, operating handle l2, a plurality of switch decks or assemblies I3 assembled on a common shaft Il (Figure 4), and an indexing mechanism I5, the shaft I6 of which is operatively connected with the shaft I4 of the switch. A feature of the invention is that the shafts I4 and I6 are separate, and detachably connected, so that-the shaft I4 may be .of a length suitable to accommodate the number of switch decks desired, the

shaft I i being uniform for switches of the samev 3 type, regardless of the number of decks em.` ployed. The nature of the connection between the shafts I4 and I6 is immaterial, and may employ a key, pin, or other suitable conventional means. In any applications. the indexing mechanism I3 and switch decks I3 will be assembled between panels I1 and I8, the face plate 'II and handle I2 being mounted on the opposite or exposed face of panel I1. The face plate II may. of course, vbear indicia of the positions to which the switch may be oriented with the assistance of the indexing mechanism.

The indexing mechanism is illustrated in Figure 2 and is of the starwheel type described and claimed in Patent No. 2,411,013, and need not be described in detail. Suillce it to say that the starwheel I9 of the indexing mechanism has a tooth, and corresponding depression, for each fixed contact of the switch decks with which it is assembled, the cam followers being urged into the depressions in the starwheel I8 -by means of springs 2l.

The present invention relates particularly to the switch decks I3 each of which comprises generally a backing plate 22, stator 23 and rotor 24, all formed of non-conductive material and preferably of a plastic insulating material. Thestator 23 is annular in form, as better illustrated in Figure 5, having a circular central opening 25 to accommodate the rotor 24. Each face of the stator 23 is provided with a shallow groove 21 for each fixed contact and, intermediate the contact locations, it is provided with a peripheral projection 28 in order to lengthen the electrical leakage path between adjacent contacts and their associated `terminals. The stator is provided also with a plurality of through apertures 29 to accommodate tie rods 30 (Figure y1) for holding the plurality of switch decks together. and with tapped holes 3I to receive screws 32 for assembling the backing plate 22 to the stator, the apertures 29 having stepped walls, theaperture being of lesser diameter in the central portion 23' of its length, and of larger diameter at its respective ends, to increase the leakage paths from the adjacent contact to each tie rod 30.

The particular form of the xed contacts and their associated terminals is best illustrated in Figure 6. Each contact 33 is generally of U- shape, the ends 34 of the respective legs extending radially inwardly beyond the inner periphery of the stator and beingbent toward each other so that the contact, when forced onto the stator in one of the grooves 21, will be retained thereon by a snap action. Associated with each ilxed contact is a terminal 35, secured to the contact by means of screw 36 and lock washer 31, the screw 36 having engagementwith the internally tapped boss 38 formed on the central 60 portion of the contact.

The rotor 24 is formed with projecting central bosses 33 and 40 (Figure 4), which are centrally apertured to receive an operating shaft (not shown), a projection 4I being formed on the boss 38 and a corresponding recess on the boss 40 of each rotor so that. when a plurality of switch decks are assembled together, the projection 4I on one rotor will enter the corresponding recess 42 of the next rotor, bringing about correct electrical alignment of the several frotors.- 'Io the same effect as regards the stators.A each of the latter is formed with a boss 43 surrounding one of the apertures 29 the boss 43 being adapted to enter a corresponding aperture in the backing plate of thenext adjacent switch deck.

The rotors 24 are provided on either face with a series of circumferentially spaced lugs or projections 44 of the same height as the movable contact blades. to be described, for the purpose of engaging the legs 34 of the fixed contacts during rotation of the rotor in order to prevent cooking thereof or. in other words, to maintain substantially continuous engagement between the rotor and the fixed contacts during rotation of the rotor. Intermediate the lugs 44 the rotor is provided with contact blades 45 on each of its faces, corresponding blades on the opposite faces of the rotor being riveted together through the rotor to secure them thereto and to provide good electrical connection between the respective blades on opposite faces of the rotor. In the illustrated embodiment, the switch is adapted for establishing two circuits, by connecting two pairs of adjacent contacts. Therefore, in this embodiment the rotor is provided with two pairs of blades 45, each blade having two branches of which thecontact portions 48 are separated by the distance between adjacent fixed contacts. The two branches of each blade .45 are integral with a base portion 41 by which it is secured to the rotor as aforesaid. The portions 46 of the contact blades extend radially to a distance corresponding to the distance of the contact portions 34 of the fixed contacts from the axis of the switch and are adapted to engage the latter when in operative position. Each portion 46 of a contact blade is separated from its opposite corresponding member by a small helical spring 48 (Figure 4), which urges the portions 46 of each opposite pair outwardly into firm engagement with the portions 34 of the xed contacts, reducing contact resistance therebetween and increasing the load capacity of the switch.

In order to further increase the load capacity and lower the resistance of the switch, the engaging surfaces of the contacts are preferably coated with silver. The backing plate 22 is preferably provided with slots 49 at locations intermediate the locations of the fixed contacts 33 to interrupt the tracking paths which may be formed by the movable contacts during the life of the switch. That is to say, as thevmovable contacts arev rotated in the operation of the switch, small particles of silver are deposited on the backing plate and, in the course of time, the paths of the movable contacts become leakage paths. The slots 43 interrupt these leakage paths and increase their electrical resistance.

The switch assemblies or decks comprising stator, rotor, backing plate, and associated contacts. constitute. in effect, separate units which may be handled, packaged and sold as such if desired, and may be readily assembled in any desired number on a common shaft in order to multiply the number ,of circuits controlled by the switch. As stated before, when the several parts have been assembled and the stator riveted to the backing plate, all of the 'parts are interlocked in such a manner that no pa gnay be inadvertently detached. By virtue of the features described above in connection with the design of the stator, the movable. contact blades. the fixed contacts, etc., the switch isgiven a high load capacity in comparison toits size, and a very low contact resistance.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A rotary switch comprising an annular stator of non-conductive material, a rotor of nonconductive material mounted within the central opening of said stator, a plurality of contacts mounted on said stator, each said contact having two branches embracing therebetween a portion of said stator and extending inwardly into alignment with a portion of said rotor at opposite points axially thereof, and a plurality of contact units on said rotor, each said contact unit comprising a pair of blades axially spaced and embracing therebetween a portion of said rotor. each said blade comprising two branches adapted to engage respective stator contacts simultaneously, said pair of blades being in electrical contact with each other and having tip portions on said branches adapted to engage the inner, opposing faces of said stator contact branches and to form parallel connections between the engaged stator contacts, and a spring under compression between each opposed pair of tip portions.

2. A switch according to claim l, said stator contacts being generally U-shaped with the branches extending radially inward and the portion connecting said branches lying against the outer periphery of said stator.

3. A switch according to claim 2, the respective branches of each said stator contact lying in radial notches formed in the respective faces of said stator, and the inner ends of said branches being deformed toward each other, said contacts being of resilient material whereby they are retained in place on said stator by spring action, and serve to retain said rotor in place.

4. A switch according to claim 3, comprising a non-conducting disc secured to a face of said stator and serving to secure said contacts and rotor in place.

5. A switch according to claim l, the blades of each rotor contact unit pair being riveted together through the rotor adjacent their inner ends.

6. A switch according to claim 1, including plates of non-conductive material secured to the respective faces of said stator, said plates being formed with radial slots between stator contacts to interrupt the tracking paths therebetween.

7. A rotary switch comprising an annular stator of non-conductive material, a rotor of nonconductive material mounted within the central opening of said stator, a plurality of contacts mounted on said stator, each said contact having two branches embracing therebetween a portion of said stator and extending inwardly into alignment with a portion of said rotor at opposite points axially thereof, and a plurality of contact units on said rotor, said contact units being adapted to engage respective stator contacts simultaneously, each said contact unit engaging both branches of one of said stator contacts, the respective faces of said rotor being provided with spaced projections between contact units for engaging the stator contacts to prevent cooking of said rotor during rotation thereof.

LEON G. BARRY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,319,503 Glogau May 18, 1943 2,436,750 Gray Feb. 24, 1948 2,465,933 Rowe Mar. 29, 1949 2,466,072 Batcheller Apr. 5, 1949

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