US2440578A

US2440578A - Rotary switch contact assembly

Info

Publication number: US2440578A
Application number: US672394A
Authority: US
Inventors: Walter L Dietrich
Original assignee: Arrow Hart and Hegeman Electric Co
Current assignee: Arrow Hart and Hegeman Electric Co
Priority date: 1946-05-27
Filing date: 1946-05-27
Publication date: 1948-04-27
Anticipated expiration: 1965-04-27

Description

April 27, 1948. w, D mCH 2,440,578

ROTARY SWITCH CONTACT ASSEIBLY V Filed lay 27, 1946 2 Sheets-Sheet 1 Aprii 2-7, 1948 w. L. DIETRICH 2,440,578 ROTARY SWITCH GONTA C'l ASSEMBLY Filed Kay 27, 1946 2 Shoots-Sheet 2 IIIHHI r .Zhvenior 14 WALTER L. DIETRICH Patented Apr. 27, 1948 I 2.440.573 no'rsmr swrrcn CONTACT sssrmnu Walter L. Dietrich, Hartfo The Arrow-Bart Hartford, Conn,

rd, Conn, assignor to 8: Hegeman Electric Company, a corporation of Connecticut Application May 27, 1946, Serial No. 672,394 14 Claims. (01. 200-155) This invention relates to rotary electric switches and more particularly to switches wherein the switch blades and stationary contacts are required to carry and to break high amperage electric currents.

It is an object of the invention to provide rotary blades or plates with adequate cross-sectional area to carry several hundred amperes and also with flexibility for the purpose of providing adequate pressure, yet permitting contact separation without the exercise of excessive rotary force.

Another object of the invention is to provide improved means associated with the rotary switch blades and the stationary contacts for minimizing cooling and snufling out the arc incident to contact separation.

Another object is to element which will also thus to keep at a mini of switch parts.

Other objects and advantages of the invention will appear as the invention is described in the accompanying drawings.

In the drawings- Fig. 1 is a plan view partly broken away, of a switch blade assembly embodying the invention;

Fig. 2 is a transversesection view taken along line 2-2 of Fig. 1;

Fig. 3 is a section view taken along line 3-3 oiFig. 2; and

Fig. 4 is a detailed perspective view of one of provide an arc snumng function as a guide and um the required number the stationarycontacts.

the invention is 1 Referring to the drawings, shown as made for embodiment in a rotary electric switch having two stationary contacts which are bridged by a two blade rotary bridging contact. It will become obvious to those skilled in the art, as the invention is described, that the invention is equally applicable to switches having a greater number of fixed contacts and blades.

The fixed contact members Ill and i2 comprise flat blocks or bars of copper or other highly conductive material. These fixed contacts are alike and therefore only one will be described in detail. The inner or contacting ends are enlarged in arcuate form to provide a contact head l3; whose top and bottom surfaces I31: and l3b are flat and in the plane of the main body of the contact. The inner portion of the contact head is cut away from both the top and bottom surfaces to provide inner contact surfaces I la and I lb a step below and above the surfaces Ba and l3b. Preferably the.end portions of the inner step it oi the contact head are convergently inclined as at long, for the maximum period,

I to and beveled. The stationary contacts are or may be spaced apart around the axis of a rotary switch blade assembly.

The rotary switch blade assembly is built up of a number of elements. Top and bottom switch plates 22 and 24 he against the top and bottom surfaces respectively, of circular discs 26 and 28 made of insulating material. For convenience in description the plates 22 and 24 will be termed primary bridging members. Between the discs 26 and 28 are

switch plates

34 and 36 which are spaced from the discs by conductive washers 82 and 33. For convenient reference the

plates

34 and 36 will. be termed secondary bridging members. They are spaced apart by three conductive washers 38 to provide room :lor a middle insulating disc 40 between the

secondary bridging members

34 and 36. All 01 the switch plates, washers and both discs 26 and 28 are preferably provided with a square central aperture for the reception of a switch operating shaft (not shown) by means of which the rotary switch blade assembly may be turned. The plates, washers and discs 28 and 28 are firmly secured together as by rivets; but the middle disc is free within the assembly, being retained between the

plates

34 and 38 so that the assembly may rotate while the middle disc remains stationary as will hereinafter be more fully described.

Referring now in detail to the several elements which make assembly, the primary bridging members 22 and 24 are illustrated as plates stamped in L-shape from sheet metal. Since they are identical in form, only one need be described. The bridging plate member 22 has a central portion 23 from which arms 25, 21 extend radially. The arms are slotted to provide parallel blades 25:; and 25b and 21a and 21b. By reason of the slotting of the radially extending arms the alignment of the movable contacts with the fixed contacts and a maximum number of points of contact between the switch plates and fixed contacts are provided. Preferably the side edges at the ends of the blades are outwardly flared, as for example, at 25! to facilitate contact engagement and disengagement and to bring about a quicker complete engagement of the individual blade of the movable contact arms as the movable switch member is moved into contacting position and also to prothe complete engagement of the individual arms when the movable contact ls moved for contact separation.

In order to provide an adequate amount of contact surface in engagement between the fixed up the rotary switch blade scribed.

. contact members.

and movable contact member so as to prevent overheating or the individualcontact members, the secondary bridging members 84, 36 are provided. Since these members are alike only one will be de- They are-stamped from sheet metal as L-shaped plates. The member 34 comprises a central portion 39 from. which extends radial arms 35 and 31 which are radially slotted to form parallel blades 35a, 85b and 31d and kill). The secondary bridging contacts 35 and db may be flat throughout and are designed and proportioned to have the ends of their blades engage the upper and lower contact suri'aces ids and Nb respectively, of the fixed contact members.

The blades 35a, 35b andlla, 37b are located directly below and parallel to the blades ado, 25b and t'la, 2%, respectively.

The primary bridging contact members 22 and 2d lie upon and are secured against the outer surfaces, 1. e. the top and bottom surfaces, respectively, of the insulating disc members it and 28, respectively. These disc members are alike and the cooperation of the primary bridging members with them is similar. Therefore, reference will be made to only one (26) in describing them in detail. The disc 26 is preferably made from sheet insulation such as fiber glass. Cut into the periphery at points spaced 90 apart are recesses 26a, 25b for the reception of the ends of the blades 25a, 25b and Zla, 2%, respectively, said ends being bent or inwardly oiiset out of the plane of the central portion 23 so as to be in a position for their inner surfaces to engage the top contact surfaces ltd oi the fixed contact members. Preferably, the recesses Eta and 2b!) are of approximately the size and shape or very slightly larger than the portions of the blades which lie .in them.

Of like form and in like manner the ends of similar blades of the plate member 22 engage the bottom contact surfaces 1153b.

Loosely mountedin the center of the movable switch plate assembly, the disc shaped insulating plate (it has a circular central aperture 62 within which are located the spacing washers 38, In the periphery of the disc Gil are cut notches cc and G6 at points preferably 90 apart for the reception of the contact heads 98 of the fixed contact members. These notches G6 and it are of the same size and contour as said contact head so as to form a close fit with the contact heads when the device is assembled. Preferably the thickness of the plate 13d will be slightly less than the thickness of the inner step it of the fixed Since the plate 36. is located between the bridging contact members 80, and 3b it is necessary for the disc St to be or less thiclz ness than the step i l to enable the blades oi the secondary bridging members 35 and 86 tosort pressure upon the surfaces of the steps 85 as the fixed and movable contact parts come into engagement.

To hold the middle disc lit stationary and to enable it to guide the whole switch blade assem bly as the assembly rotates, lugs it extend radially from the disc Gil at diametrically opposite points and are held by the switch casing or base at or other stationary part of the switch mounting.

From the foregoing the operation of the parts may be understood. Assuming thtfbrldgihg contacts tobe engaged with the fixed contacts. The

ends of the blades of the primary-bridging mem- I bers 2'2 and M will press upon the upp r and and without increasing the width,

members i" and it while the ends or the blades ot the secondary bridging contact members 34' 7, gagement of the two all ' forms a guide and 93a; in like manner the blades and 38 press upon the upper and lower contact surfaces, respectively, of the steps id of the fixed contact members.

Upon turning the switch blade assembly the trailing blades of the secondary bridging members will separate from the step it of the fixed contacts-slightly before the trailing blades of the primary bridging members separate from the fixed contacts. Contact engagement will, of course, be in the opposite sequence. However, the blades (for example 250., 2M) of the primary bridging members will separate substantially simultaneously from the fixed contacts surfaces (for example 35a, dlc) oi the secondary bridging members will separate substantially simultaneously from the fixed contact steps i l. Conversely, contact engagement of the fixed contacts with the two blades of the pry bridging members will, of course, occur simultaneously; and also the enblades of the secondary bridging members with the fixed contact steps ill be simultaneous.

From the foregoing it may now be understood that the provision or four separate arms on the bridging contacts on different levels (two primary and two secondary arms) provides the necessary cross-sectional area to carry currents in the neighborhood of 500 amperes. The provision of the four arms also provides the necessary ilexi= bility for short arms, thearms necessarily being short (as illustrated) because, in cer ain cases of space limitations.

The slotting of each arm (thereby providing two blades in each) points of contact and better self-alignments when the blades engage the fixed contacts.

The inside or middle stationary insulating disc also an arc barrier to limit the play of the arc incident to switch operation. At the same time the rotating outside insulating .discs or barriers act as are quenching or arc snumng means.

Modifications within the scope of my invention will occur to those skilled in the art. Therefore I do not limit it to the specific embodiment illustrated in the drawings.

What 1 claim is:

1. In a rotary switch, fixed contact members each having contact surfaces on two levels and facing in the same direction, a rotary bridging contact assembly comprising a bridging memher having arms to slidingly engage with the contact surface on one level, a second bridging memher having arms, an insulating disc between said bridging members in a, plane above both levels of contact surface, means to secure said disc and bridging memberstogether, said disc having recesses in its periphery, the ends of the arms oi said second bridging member being ofiset into said recesses and engageable with the fixed contact surfaces on a second level.

2. In a rotary switch, fixed contact members each having contact surfaces on two levels and facing in the same direction, a, rotary bridging contact assembly comprising a bridging member having arms to slidingly engage with the contact suriace on one level, a second bridging member having arms, an insulating discbetween said bridging members, means to secure said disc and bridging members together, said disc having recesses in: its periphery, the ends of the arms of provides a large number ofsaid second bridging member being offset into said recesses and tact surfaces on a second level, and an insulating disc which is coaxial with said first disc and is fixedly secured in relation to said fixed contact members and has recesses receiving the portions of said fixed contacts on which are located said first-level contact surfaces.

3. In a rotary switch, fixed contact members each having a pair of contact surfaces on one side thereof and on different levels and a similar pair on the opposite side, also on different levels.

a rotary bridging contact assembly comprising a pair of movable insulating discs, 3, pair of bridging members one overlying the outside surface of one disc and the other overlying the outside surface of the other disc, a second pair of bridging members located between said discs. means securing all of said discs and bridging members together for rotation as a unit, a stationary insulating disc located between said second pair of bridging members and guiding the rotary movement of said movable discs and bridging members.

4. A switch as claimed in claim 3 wherein each bridging member has radially extending arms and is slotted to provide additional points of contact engagement and better alignment with the fixed contact surface that they engage.

5. In a rotary switch, fixed contact members each having a pair of contact surfaces on one side thereof and on diiferent levels and a similar pair on the opposite side also on different levels, a. rotary bridging contact assembly comprising a pair of movable insulating discs, a pair of bridging members one overlying the outside sllr face of one disc and the other overlying the outside surface of the other disc, a second pair of bridging members located between said discs, means securing all of said discs and bridging members together for rotation as a unit, a stationary insulating disc located between said second pair of bridging members and guiding the rotary movement of said movable discs and bridging members, said stationary disc having recesses in its periphery receiving the contact surfaces of said fixed contacts, said stationary and movable discs cooperating with said contact members to quench arcs occurring upon contact separation.

6. A switch as claimed in claim 5 wherein each bridging member has radially extending arms and is slotted to provide additional points of contact engagement and better alignment with the fixed contact surface that they engage.

7. In a rotary switch, fixed contact members each having a pair of contact surfaces on one side thereof and on different levels and a similar pair on the opposite side also on different levels, a. rotary bridging contact assembly comprising a pair of movable insulating discs, a pair of bridging members one overlying the outside surface of one disc and the other overlying the outside surface of the other disc, a, second pair.

of bridging members located between said discs. means'securingall of said discs and bridging members together for rotation as a unit, a stationary insulating disc located between said second pair of bridging members and guiding the rotary movement of said movable discs and bridging members, said movable discs having recesses in their periphery into which the end portions of the outside bridging members are offset, to permit sliding. engagement of said offset ends with one level of said fixed contact surengageable with the fixed con faces, said stationary and movable discs coop- .and is slotted to side surface of'the other disc, a second I rotational axis of crating with said contact members to quench arcs occurring upon contact separation.

8. A switch as claimed in claim 7 wherein each bridging member has radially extending arms provide additional points of contact engagement and better alignment.

9. In a rotary switch, fixed contact members eachhaving a pair of contact surfaces on one side thereof and on different levels and a similar pair on the opposite side also on different levels, a rotary bridging contact assembly comprising a pair of movable insulating discs, a pair of bridging members one overlying the outside surface of one disc and the other overlying the outpair of bridging members located between said discs. means securing all of said discs and bridging members together for rotation as a unit, a stationary insulating disc located between said second pair of bridging members and guiding the rotary movement of said movable discs and bridging members, said stationary disc having recesses in its periphery receiving the contact surfaces of said fixed contacts, said movable discs having recesses in their periphery into which the end portions or the outside bridging members are offset, to permit sliding engagement of said ofiset ends with one level of said fixed contact surfaces, said stationary and movable discs cooperating with said contact members to quench arcs occurring upon contact separation,

10. A switch as claimed in claim 9 wherein each bridging member has radially extending arms and is slotted to provide additional points or contact engagement and better alignment.

11. In a rotary switch, fixed contact members each having a head portion with outer contact surfaces and inner contact surfaces, the inner surfaces of each head portion being closer to the the switch and in difi'erent more closely spaced planes than the outer surfaces, a rotary bridging contact assembly comprising a pair of movable insulating discs, a pair of bridging contact plates overlying the outside surfaces of said discs, 2. second pair of bridging contact plates between said discs and a stationary insulating disc between said second pair of contact plates, means securing together said movable discs and all said bridging contact members for rotation as a unit, said stationary disc acting to guide said rotary unit.

12. A switch as claimed in claim 11 wherein the periphery of the movable discs are recessed and the ends of the outer bridging members are offset into said recesses to slidingly engage the outer surfaces of said fixed contacts.

13. A switch as claimed in claim 11 wherein said stationary disc has recesses in its periphery receiving the head portions of the stationary contacts, and said discs cooperate with the contacts to quench arcs incipient upon contact separation.

14. A switch as claimed in claim 11 wherein the periphery of the movable discs are recessed and the ends of the outer bridging members are offset into said recesses to slidingly engage the outer surfaces of said fixed contacts, and said stationary disc has recesses in its periphery receiving the head tacts, and said discs cooperate with the contacts to quench arcs incipient upon contact separation.

WALTER L. DIE'I'RICH.

(Merenceson following page) portions of the stationary con- 1 1 v REFEBENCESCITED" Name Number Date Perm Aug. 2 new 8 Heme mm I Hansen may 2, 1916 Carlson Aug. 26, 1924. Lflebemm New 1926 Emil July g7, wee