US2709734A - Electric contact arc-suppressing rotary snap switches - Google Patents

Description

J. T. COLIZ May 31; 1955 ELECTRIC CONTACT ARC-SUPPRESSING ROTARY SNAP SWITCHES Filed Aug. 9, 1951 6 Sheets-Sheet l May 31, 1955 Y J, 1', com: 2,709,734

I ELECTRIC CONTACT ARC-SUPPRESSING ROTARY SNAP SWITCHES Filed Aug. 9, 1951 6 Sheets-$heet 2 17 f If f fazed c7m w225@,

J. .T. COLIZ May 31, 1955 ELECTRIC CONTACT ARC-SUPPRESSING ROTARY SNAP SWITCHES Filed Aug. 9, 1951 6- Sheets-Sheet 3 J. T. COLIZ May 31, 1955 ELECTRIC CONTACT ARC-SUPPRESSING ROTARY SNAP SWITCHES Filed Aug. 9. 1951 6 Sheets-Sheet4 May 31, 1955 J. T. couz 2,709,734

ELECTRIC CONTACT ARC-SUPPRESSING ROTARY SNAP SWITCHES Filed Aug. 9, 1951 6 Sheets-Sheet 5 J. T. couz 2,709,734

SNAP SWITCHES May 31, 1955 ELECTRIC CONTACT mc-suwmsssmc ROTARY Filed Aug. 9. 1951 6 Sheets-Sheet 6 i d & w 9 6 M Q0 9 NM 9 Tw I W a )QO/ 2 4 I W ELECTRKC CONTA C'l ARtC-SUPPRESSING RDTARY SNAP SWETCHES \l'ames T. Colic, New Frovidence, N. 3., assignor to United States instrument Corporation, Summit, N. 1., a cor- (,laiins. (Cl. 260- 144) This invention relates in general to rotary electric switches of the type including stationary or stator contacts and rotary or rotor contacts for sole-c .ng power sources or for switching in circuits that carry heavy electrical loads. it is well known that in switches of this type when the current-carrying rotor contacts move away from the stator contacts, the electrical resistance at the contacts rises with a consequent rise in ternoerature, and when the rotor contacts are relatively close to the stator contacts, that is, separated by only a few millionths of an inch, an extremely high strength electric field, of the order of millions of volts per inch, is created by the rise in voltage between the separating contacts. An arc is thus established which, it not broken when the contacts have reached r ii'num separation, causes current to continue to flow through the so that the intense heat will fuse the contacts until they are destroyed and will destroy the ins: sting material supporting the contacts. Should the sepa "on of the contacts be great enough to extinguish the arc, the destructive effects will be less acute progressive but will seriously shorten the life of the switch. Moreover. in a switch for selecting power sources, the contacts coin "ted to the different sources are in the same chamber in which the arc is formed; and consequently an arc may cause a short circuit between the adjacent contacts of the different sources, and the arc may be so intense as to destroy the switch immediately upon formation of the arc.

Therefore, a prime object of the invention is to provide a switch of the general nature described which shall include novel and improved means for suppressing or preventing are between the stationary and movable contacts and between contacts connected to dilierent sources.

Another object is to provide in such a switch novel and improved contact elements which shall posess maximum heat-conductivity from the point of separation of the stationary and movable contact elements.

A further object is to provide in a rotary electric switch a novel and improved construction and combination of spring pressed rotor contact elements, stator contact elements and arc-suppressor plates whereby the ionized gases formed by an are between the movable and the stationary contacts are caused to spread and come into contact with large areas of the suppressor plates, and said suppressor plates partially enclose the rotor contact elements and conduct heat therefrom and also serve as guides to ensure proper alignment and engagement of the rotor contacts and stationary contacts so as to prevent jamming of the rotor contacts.

The invention is directed especially to switches having a plurality of decks or switch assemblies, each comprising a stator, rotor, and side and end plates or walls, the several decks being secured together in superposed relation and the rotors of all the decks being operated by the same shaft and indexing mechanism; and another object of the invention is to provide such a switch deck the parts of which shall be few, simple construction and easy to assemble, to repair and to replace.

Patented May Other objects, advantages and results of the inv" will be brought out by the following description in corn junction with the accompanying drawings, in which Figure l is a side elevational view with portions h" away and shown in section, illustrating a multiple-roar switch embodying the invention;

Figures 2, 3 and 4 are transverse sectional views, proximately on the planes of the lines and 2-4, respectively, of Figure 1;

Figure 5 is a transverse sectional view on a redo ed scale, taken approximately on the plane of the line of Figure 7;

Figure 6 is a similar view, taken approximately on the plane of the line 6-6 of Figure 7;

Figure 7 is a entral vertical lon itudinal sectional view through one of the decks of the switch;

igure 8 is a transverse sectional view, approximately on the plane of the line 88 of Figure l;

Figure 9 is an end elevational view of the switch from the plane of the line 9-) of Figure 1;

Figure 10 is an exploded perspective view of one of the decks with some of the stator contacts and some of the deck-spacer or end plates omitted;

Figure 11 is an end elevational view of one of the deck housing rings;

Figure 12 is a detached plan view of one of the rotor contact assemblies, viewing the same from the side opposite that shown in Figure 5;

Figure 13 is a View similar to Figure l, showing a modification of the invention;

Figure 14 is a transverse sectional view, approximately on the plane of the line 14-44 of Figure 13;

Figure 15 is a transverse vertical sectional view through one of the deck assemblies, approximately on the plane of the line 1515 of Figure 14;

Figures l6, l7 and 18 are transverse sectional views, approximately on the planes of the l nes 16-16, l'L-l) and ill-ill, respectively, of Figure 15;

Figure 19 is a plan view of one of the stationary sup pressor plates;

Figure 20 is a similar view of one of the rotary arc suppressor plates;

Figure 2i is a schematic side elevational view of one of the deck assemblies with portions bro n away for clearness in illustration, showing the relationship of the contact elements, the arc suppressor plates and the deck spacer or end plates;

Figure 22 is a similar view with the rotor rotated through an angle of ninety degrees (90);

Figure 23 is an enlarged schematic plan view of the rotary contact assembly shown in Figures 1 to 12, inclusive, and one of the stator contacts;

Figure 24 is a view approximately on the plane of the line 24-24 of Figure 23;

Figure 25 is an enlarged fragmentary schematic view, approximately on the plane of the line 25-45 of Figure 23, and with the arc suppressor plates added;

Figure 26 is a View similar to Figure 3, showing the rotor contact assembly illustrated in Figures 13 to 20, inclusive, and

Figure 27 is a view approximately on the plane of the line 2727 of Figure 26.

Specifically describing the embodiment of the invention illustrated in Figures l to l2, inclusive, the switch comprises a base plate A, a plurality of switch decks or assemblies B, a common tubular shaft C of polygonal cross section with which is telescopically associated a shaft D which is connected to the operating shaft E of a known type of indexing mechanism F that has an operating knob G. The shaft 5 is journaled in the casing of the indexing mechanism and is separably con nected to the shaft D in known manner so that the length of the shafts C and D may be of a length to accommodate the number of switch decks desired to be included in the switch and the shaft E may be of the same length for all switches of the same type, regardless of the number of decks embodied in the switch. The opposite end of the shaft D has a suitable bearing H in an end plate 1 of the deck adjacent the base plate A. The decks, base plate and indexing mechanism are clamped together in known manner by bolts 2 that extend through continuous electrical insulating tubes 3 which in turn pass through openings in the deck end or spacer plates 4, the heads of the bolts being seated in recesses in the base plate A and nuts 6 being clamped against the casing of the indexing mechanism.

The indexing mechanism is of the standard snap action type, for example, such as described in Patent No. 2,411,013, and need not he described in detail. The mechanism includes a star wheel formed with a tooth and a corresponding depression for each stationary or stator contact of the switch decks with which it is assembled, and spring-pressed cam followers cooperating with the teeth and depressions of the star wheel to index the rotor contacts with respect to the stator contacts in the usual way.

The structure so far described is broadly old and the present invention resides in the construction of the switch decks, particularly the rotor contact assembly and arc-suppressor plates. As shown, each switch deck B comprises a rotor assembly that includes a rotor contact element I (Figs. 5, 12, 23 and 24) formed to two resilient electrical conducting sections 7 each of which has a central ring-like portion and diametrically opposide radially projecting contact portions 8. The contact portions 8 are cup-shaped and the sections 7 are mechanically and electrically connected with the concave surtace of each portion 8 of each section facing the concave surface of one portion of the other section and with the contact portions of the two sections normally held in spaced relation by the inherent resiliency of the sections 7 preferably supplemented by coil springs 9 interposed between said contact portion 8. The sections '7 may be connected together in any suitable way, but as shown, a fastener element has a circular portion 10 abutting the outer side of one of the sections 7 and segmental flanges 11 projecting from the portion 10 through arcuate slots 12 in the sections 7 and bent or clinched over the outer side of the other section 7. The fastener element is formed with a polygonal opening 13 to nicely fit the shaft C so that the rotor contact element 1 will rotate with the shaft.

Each rotor contact element 1 is enclosed within a housing which includes a hollow cylindrical housing section or ring 14 encircling the rotor contact element, opposite ends of which have notches 15 in which are seated the arms and contact portions 16 of U-shaped stator contact elements 17 between and into and out of engagement with which are movable the contact units comprising the pairs of contact portions 8. An arc'suppres sor ring 18 is disposed at each end of the housing ring 14 and has notches 19 and openings 20 to receive portions of the stator contact elements and the insulating tubes 3, respectively. Within each of the suppressor rings 18 is nicely fitted a fixed suppressor plate 21 to close the corresponding end of the opening through the housing section, said plate having notches 22 the sides of which nicely engage the edges of the contact portions 16 of the stator contact elements. The plates 21 have central openings 23 providing clearance for the shaft C, and each suppressor plate is overlaid by an end or deck spacer plate 4 which is fixedly arranged as by screws 25 passing through the plate and into the stator contact elements 17 (Figs. 7 and 8). The end plates 4 also have central openings 25 for the shaft C, as well as openings 27 for the tubes 3 of the tie-bolts 2.

Cooperating with the suppressor plates 21 and suppressor rings 18 are rotary suppressor plates 23 and 29 at each of opposite sides of the rotor contact element 1 (Figs. 4 to 7 and 10), which have their edge portions underlying the corresponding arms 16 of the stator contact elements 17 and have diametrically opposite notches 30 and 31, respectively, embracing the contact portions 3 of the rotor contact element in such a way as to permit said contact portions to move through the notches under the influence of the springs 9 and at the same time prevent twisting of said contact portions or misalignment thereof with the contact portions 16 of the stator contact elements as the rotor contacts 8 move into engagement with the stator contacts 16. Desirably, the contact portions 8 are provided with lateral lugs 8a to engage the adjacent suppressor plate 28 so as to limit the movement of the contact portions 8 under the influence of the springs 9.

It will be understood by those skilled in the art that the housing ring 14, the tie-bolt tubes 3, the suppressor rings 18, end plates 4, and suppressor plates 21, 28 and 29, will be formed of electrically non-conductive material preferably a plastic insulating material such as a phenolic resin like Bakelite or polytetrafluoroethylene like Teflon. It is especially preferable that the suppressor plates 21 and 29 be formed of Teflon because of its superior arc-suppressing qualities.

With this construction, it will be observed that the decks can be easily and quickly disassembled by the removal of the screws 25 and all parts may be cleaned or replaced easily, quickly and individually except the rotary contact element I which must be replaced as a unit; and the arc-suppressing plates, both rotary and stationary, may be reversed, thus doubling the life of these parts.

The decks may be connected in electric circuit in any suitable way, but as shown, terminal screws 32 are threaded into the respective stator contact elements 17, and depending upon the purpose for which the switch is intended, a plurality of the stator contact elements may be electrically connected together by a bar or jumper 33. Each deck is basically a two-position single pole switch, but with the external jumper 33 the deck becomes a single pole double throw switch. Byremoving the jumper and any two opposite stator contact elements, the deck is transformed into a single pole single throw on-ofl. switch. With minor modifications of the rotor parts and by changing the number of stator contacts and the number of rotor contacts, many other types of action may be obtained. The complete switch with three decks as described is capable of breaking and switching three-phase power circuits.

In operation of the switch, any arcs that may be formed as the rotor contacts leave the stator contacts will be spread and dissipated in the space 34 between the relatively cool suppressor plates 21 and 29 (Figs. 7 and 22), and to prevent the formation of a continuous conductive path by accumulation of particles caused by erosion under overload, the fixed suppressor plates 21 may be formed with perforations 35. At the same time, said suppressor plates conduct heat from the rotor contact portions 8. The heat from the arc is also quickly condiicted away from the point of engagement of the contact members, as indicated by the arrows 36 in Figures 23, 24 and 25, and is distributed over a wide area of the ring-like central portions of the sections 7 of the rotor contact element I. Furthermore, the electric current is divided so that half of it passes through each of the sections of the rotor contact element I and each of the arms of the stator contact elements 17, as shown by the arrows in Figure 21, as a consequence of which the heat generated by the current is divided. It will thus be clear that the electron emission from the arc is suppressed through the cooling of the contacts and of the gases, by conduction through the suppressor plates and through the rotor contact element to the atmosphere.

The heat generated is maintained at a minimum by the division of the current, and the contact surfaces at which the arc is generated are quickly isolated from each other upon their separation. The main portions of the stator contacts are exposed to the atmosphere for rapid heat dissipation. It will also be observed that there will be a minimum of possibility of a short circuit between the adjacent contacts of ditferent power sources, particularly because the travel of an are between adjacent contacts would be prevented by the constricted space 34 between the suppressor plates.

Figures 13 to illustrate another type of switch embodying the same general idea and construction, the switch comprising a base plate K, a plurality of switch decks L and an indexing mechanism M which may be identical with the indexing mechanism F hereinbefore described, the base plates, deck and indexing mechanism being clamped together by tie-bolts 37 like the tie-bolts 2. The switch has a common shaft N of insulating material for all of the decks which is journaled at one end 38 in an end plate 39 of one of the decks, said shaft having fitted therein, preferably by molding, a shaft 0 which is separably connected to the shaft 1 of the indexing mechanism.

The decks are identical in construction and each includes a rotor contact element Q that comprises two ring-like sections 4t (Figs. 17, 26, and 27) that are mechanically and electrically connected as by lugs 41 spot welded together as indicated at 42 at diametrically opposite points. Disposed at an angle of ninety degrees (90) to the lugs 41 are diametrically opposite contact portions 43 on each ring section, said contact portions being cup-shaped with their concave surfaces facing each other with springs 44 between them which tend to spring the contact portions apart and into engagement with the stator contacts to be described. The rotor contact element Q is secured between two disks 45 of electrical insulating material each of which has a circular rabbet 4d surrounding the hub portion 37 and complementary to the rabbet of the other disk to receive the contact element Q between them, each disk having a notch 48 to loosely receive and guide the corresponding contact portion 43 and also having recesses 49 for the lugs 41. The disks have central openings 59 to nicely fit the shaft N so that the rotor will turn with the shaft. The disks are secured together in any suitable manner but preferably they are formed of a synthetic resinous material and are adhesivcly secured together. The disks may be molded or machined as desired.

The housing for the rotor is shown as a molded block 51 formed with a central opening 52 in which the rotor is mounted. U-shaped stationary contact elements 53 generally similar to the elements 17 are secured on the block with their arms or contact portions 54 extending into the opening 52 at opposite sides of the plane of the rotor contacts 43. As shown, the arms 54 are crimped or bent inwardly and the end surfaces of the housing block have notches 55 for rigidly securing the contact elements on the housing, and each contact element has a terminal screw 56.

Each end face of the housing block has a rectangular rabbet or recess 57 in which is firmly seated an arc-suppressor plate 58 similar to the suppressor plate 21. These arc-suppressor plates 58 are in contact with or closely spaced from the rotor disks 45 and have notches 59 the edges of which nicely engage the edges of the contact portions 54 of the respective stator contact elements 53, as best shown in Figure 14.

One end of each of the housings 51 has an end plate or deck spacer 6t rigidiy connected thereto as by rivets 61, and each deck spacer serves as a common end plate for two juxtaposed deck assembiies, except that the end plate 35? on one of the deck assemblies will be in contact with the base plate K instead of being connected to another deck assembly. The end plate 60 and the housing 6 51 have aligned openings 62 for the insulating tubes 63 of the tie-bolts 37.

The operation of this form of switch is in general similar to that above described, the are being suppressed between the suppressor plate 555 and the rotor disk 45' and the current being divided through the stator contacts and the two sections 40 of the rotor contact element Q.

Each deck assembly constitutes a separate and independent unit that can be combined with any desired number of similar units and each unit comprises a small number of simple parts that can be easily and quickly assembled and disassembled, both during original manufacture and for repair or repiacemcnt of parts. At the same time, the assembly possesses extraordinary arc-suppressing properties which makes it possible to provide a switch of minimum size capable of handling relatively extraordinary heavy electrical loads.

While two preferred forms of the invention have been illustrated and described, it should be understood that this is primarily for the purpose of illustrating the principles of the invention and that the construction of the switch may be widely modified and changed within the spirit and scope of the invention.

Having thus described the invention, what I claim is:

l. A rotary switch comprising a stator housing section of non-conductive material having opposite ends and having an opening therethrough extending from end to end of said housing section, a stationary contact mounted on said housing section and having two flat arms in spaced opposed relation and each extending into said opening at one end thereof, a rotor contact element including an approximately fiat central portion rotatably mounted within said housing section and having a radially disposed contact unit comprising a pair of spaced opposed contact portions connected to said central portion and movable between said spaced arms of the stationary contact and each into and out of engagement with one of said spaced arms of the stationary contact upon rotation of said central portion in opposite directions, respectively, an approximately flat layer of non-conductive material disposed within said housing section at each end thereof and in spaced relation to one side of said central portion of said rotor contact element and having a notch in which the corresponding arm of the stationary contact nicely fits so that each of said layers of nonconductive material and said arms of the stationary contact close said opening in the stator housing section at one end thereof, and at least one plate of non-conductive material loosely filling the space between each of opposite sides of said central portion of said rotor contact element and the corresponding said layer of non-conductive material with the edge portion of said non-conductive plate closeiy underlying one of said arms of the stationary contact in spaced relation to said fiat layer of non-conductive material and having a notch through which the adjacent one of said contact portions projects, so that the gases that may be formed by any are produced between said stationary contact arms and said rotor contact portions will enter between said layers of non-conductive material and said plates of non-conductive material and hereby will be cooled to suppress the arc.

2. A rotary switch as defined in claim 1, with the addition of an end plate of non-conductive material overlying each said layer of non-conductive material and the corresponding arm of said stationary contact.

3. A rotary switch as defined in claim #l, wherein there are a phiraiity of said stationary contacts and said rotor contact element comprises two coaxial opposed ringlike sections electrically connected together, each having two or" said contact portions spaced circumferentially and each in spaced opposed relation to one contact portion of said other section, whereby to divide the electric current through said stationary contacts and said sections of the rotor contact element, and said plates of non-conductive material substantially fill the spaces between said 7 ring-like sections and said end layers of non-conductive material.

4. A rotary switch as defined in claim #1, wherein said stator housing section is a ring having notches in its edges in which said arms of said stationary contacts are seated, and each said layers of non-conductive material comprises a fiat ring having a notch partially embracing the edges of one of said arms of the stationary contact, and a closure plate of non-conductive material fitted in and closing the central opening in said flat ring and having a notch embracing the other edge portions of said arm of the stationary contact.

5. A rotary switch as defined in claim #1, wherein said stator housing section is a ring having notches in its edges in which said arms of said stationary contacts are seated, and each said layers of non-conductive material comprises a fiat ring having a notch partially embracing the edges of one of said arms of the stationary contact, and a closure plate of non-conductive material fitted in and closing the central opening in said fiat ring and having a notch embracing the other edge portions of said arm of the stationary contact, and with the addition of an end plate of non-conductive material overlying each said fiat ring and said closure plate and the corresponding arm of the stationary contact and secured to said arm,

6. A rotary switch as defined in claim #1, wherein there are a plurality of said stationary contacts and said rotor contact element comprises two coaxial opposed ring-like sections electrically connected together, each having two of said contact portions spaced circumferentially and each in spaced opposed relation to one contact portion of the other section, whereby to divide the electric current through said stationary contacts and said sections of the rotor contact element, and said plates of non-conductive material are secured together with said ring-like sections of the rotor contact element fastened between them.

7. A rotary switch as defined in claim #1, wherein there are a plurality of said stationary contacts and said motor contact element comprises two coaxial opposed ring-like sections electrically connected together, each having two of said contact portions spaced circum- [3 ferentially and each in spaced opposed relation to one contact portion of the other section, whereby to divide the electric current through said stationary contacts and said sections of the rotor contact element, said stator housing section is a ring having notches in its edges in which said arms of said stationary contacts are seated, and each said layer of non-conductive material comprises a fiat ring having a notch partially embracing the edges of one of said arms of the stationary contact, and a closure plate of non-conductive material fitted in and closing the central opening in said flat ring and having a notch embracing the other edge portions of said arm of the stationary contact.

8. A rotary switch as defined in claim #1, wherein there are a plurality of said stationary contacts and said rotor contact element comprises two coaxial opposed ring-like sections electrically connected together, each having two of said contact portions spaced circumferentially and each in spaced opposed relation to one contact portion of the other section, whereby to divide the electric current through said stationary contacts and said sections of the rotor contact element, said stator housing section is a ring having notches in its edges in which said arms of said stationary contacts are seated, and each said layer of non-conductive material comprises flat ring having a notch partially embracing the edges of one of said arms of the stationary contact, and a closure plate of non-conductive material fitted in and closing the central opening in said flat ring and having a notch embracing the other edge portions of said arm of the stationary contact, and said plates of nonconductive material loosely fill the space between said ring-like sections and said closure plates.

References (Iited in the file of this patent UNITED STATES PATENTS 1,895,330 Kempton Jan. 24, 1933 2,038,405 Beach et al. Apr. 21, 1936 2,440,578 Dietrich Apr. 27, 1948 2,577,225 Barry Dec. 4, 1951

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