US2466072A - Electric switch - Google Patents

Description

April 5, 1949.v H. w. BA'rcHl-:LLER

ELEc'rnIc swl'rcn Filed oct. 17. 1945 I msuLATroN 7i v I/ INSULATION Patented Apr. 5, 1949 ELECTRIC SWITCH I'Hugh W. Batcheller, Newton, Mass., assgnor, by

mesne assignments, to Ark-Les Switch Corporation, Watertown, Mass., a corporation of Massachusetts Application October 17, 1945, Serial No. 622,760

This invention relates to electric switches of the rotary snap variety and is especially designed for heavy currents of the order of fifty to one hundred amperes or more.

With the development of Diesel and turbine engines as economical prime movers, electrical transmission of power in maritime vessels, locomotives and the like has developed extensively, This calls for control switches which can give reliable and continuous service with currents of considerable amperage. For reasons of personnel safety, it is desirable that such switches be enclosed in a protective casing. For economy and eliciency it is desirable that the switches conduct heavy currents for long periods without excessive heating and they be capable of large numbers of operations without excessive wear or other deterioration.

According to the present invention a heavyduty switch is provided that answers the foregoing requirements and also minimizes the spark when the switch is opened to break a circuit. These and other advantages will be apparent from the following description of a switch embodying the invention, and from the drawing, of which:

Figure 1 is a front elevation of a switch ernbodying the invention;

Figure 2 is a side elevation of the same;

Figure 3 is a section on the line 3--3 of Figure 2;

Figure 4 is a fragmentary section on the line 4-4 of Figure 3; f

Figure 5 is a fragmentary section on the line 5-5 of Figure 3;

Figure 6 is a fragmentary section on the line 6-6 of Figure 3.

Figures 1 and 2 show external aspectsl of a multiple switch having three units simultane ously operable by a single handle to open or close three different circuits. The switch elements are enclosed in a housing comprising a series of four assembled discs I0 having thick rims I2 which bear against one another to form the cylindrical wall of the housing, a front plate I4, and a back plate I6. Each disc is of suitable insulating material, preferably a molded plastic. The thick rim I2 surrounds a thinner portion 20 from both faces of which project annular ribs 22 and 24. A central opening 26 provides room for the operating shaft 30 which, as indicated in Figure 3, is preferably of square cross-section. An operating handle 32 is secured on the forward end' of the shaft 30.

As shown in Figure 1, the front plate I4 is 8 Claims. (Cl. 200-155) square, its side edges being tangent to the cylinder formed by the disc rims I2 The corners of the front plate thus project beyond the cylinder and support tubular insulating members 33 which protect fastening bolts (not shown) by which the switch can be secured to a panel or other supporting wall.

The housing is held together by four bolts I4 which extend through alined holes 3B in the disc rims I2, the front plate I4 and the back plate I6. The bolts 34 also hold a front casing 40 assembled to the housing, the casing 40 having therein a -snap-action device (not shown) which is not a part of the present invention, it being a Well known device for causing the shaft to snap through successive angles of 90 when the handle 32 is turned.

Each disc rim I2 also has six other holes 42 arranged in diametrically opposed sets of three. The holes in each set are spaced 45 apart and contain conductor rods or bolts 50 which extend from fixed switch elements 52 to the rear of the housing where they serve as terminals to be electrically connected to bus-bars, conducting cables or the like (not shown). Each switch element 52 is T-shaped, the shank of the T fitting into a notch 56 in the rim l2 of a disc I0. Each disc I0 has one pair of diametrically opposed notches 56. As shown in Figure 3, the elements 52 dc not project-outward beyond the rims of the discs I0, but if desired they can be made to extend outward to serve as terminals to be connected to circuits. Each element 52 has a hole therethrough registering with a hole 42. As shown in Figure 6, each bolt 50 passes through one of the elements 52 and has a head Sil which bears on the front surface of that element. The bolts 50 are in pairs of three different lengths in accordance with the distances of the elements 52 from the rear end of the switch housing, as indicated in Figure 2, the bolts of each pair being diametrically opposed. The heads of one such pair are shown in Figure 3. Each hole 42 in each disc rim I2 is countersunk as at 60 to receive a bolt head 58.

In the space between each pair of successive discs I0 is a movable switch element or bridging conductor 62 which, as shown, consists of two sheet metal strips 64 riveted or otherwise secured to opposite sides of a radial flange 66 of insulating material which is a part of a hub member on the shaft 30.

' The hub has a bore with a cross-section shape in the form of an eight-pointed star so that it can be mounted on the square shaft 30 in any one of a series of angular positions 45 apart. In

the plane of each hub flange 66 is mounted a fixed barrier plate 68,` this plate being interposed between the portions of the conductor elements 64 which project beyond the hub 66 to which they are secured. Each plate 68 is preferably of insulating material impervious to heat up to fairly high temperatures. For this purpose a pressed fabric of woven glass strands is satisfactory. The plate has a central circular opening large enough to accommodate the hub 66. Each plate 68 is provided with a number of semicircular projections or lugs 12 on its circumference which fit into complementary recesses in the rim I2, the plate being supported by these lugs. Each plate 68 is also provided with two opposed notches 14 shaped to receive the transverse portions of the two T-shaped switch elements 52 which cooperate with a corresponding switch element 62.

In the switch structure illustrated in the drawing there are three bridging conductors 62, each comprising a pair of strips 64 secured to a hub, the end portions of the strips being separated by a fixed barrier plate 68 and being arranged to move into and out of simultaneous contact with a corresponding pair of fixed switch elements 52. The strips 64 are of springy metal, preferably phosphor bronze, and the end portions which project beyond the hub flanges 66 are slotted to form fingers 16, as shown in Figure 3, terminating in end portions 18 which are slightly offset from the rest of the strip of which they are a part so that when they are in contact with an element 52 the fingers 16 are sprung slightly outward causing the end portions 18 to bear firmly against the element 52 and to make a good electrical contact therewith. As indicated in Figure 5, the cross portion 53 of each element 52 is thicker than the barrier 68 and the end edges are rounded or chamfered as at 80 so that ,Y the finger ends 'i8 press less firmly on the barrier 68 and are wedged apart by the rounded end edges 80 when they reach a cross portion 53 of a fixed element 52. The elements 52 are preferably of Phosphor bronze for long wear. The strips 64 are carefully shaped so that when the sets of fingers above and below the barrier are sprung apart as the ends i8 ride upon the faces of the switch elements 52, the end portions 18 will be accurately parallel and will` thus have maximum interfacial'contact with the element 52. the switch is used in circuits carrying heavy currents for which it is intended.

The use of Phosphor bronze or its equivalent in the fixed and movable switch elements is irnportant not only because of superior wearing qualities but also because arcs such as occur when the switch is opened to break a circuit tend to produce pits in bronze but tend to build up lumps on copper elements.` The pits in the bronze elements reduce but slightly the interfacial surface areas of the contacting parts, but

a small projecting lump will separate the surfaces, causing bad heating effects which have ing qualities of the switch.

The barriers 68 are preferably made with a series of small holes 82 near the periphery thereof and in the path of the end portions 18 of the casing acts to snap the shaft 30 and the switch elements 62 which are mounted thereon through an angle of 90. The snap-action mechanism maybe any one of a number of such mechanisms commonly used in rotary snap-action switches. The switch elements are so arranged that each operation of the snap-action device moves each movable element 62 into or out of contact with its pair of fixed elements 52. If all three movable elements 62 are to operate simultaneously in the same manner, that is, to open or close their circuits together, they must be angularly spaced by as is evident from the arrangement of the terminals and the holes 42 which receive them. The hubs which carry the bridging conductors 62 are each made with an axial aperture in the shape of an eight-pointed star so that these conductors can be mounted on the square shaft 30 in any one of eight positions differing by angles of 45. The elements 62 are thus interchangeable.

When the four fingers at an end of a conductor 64 move from contact with a fixed element 52, they leave successively. When three have left, the fourth for a brief instant constitutes a conducting path of substantial length and only about a quarter of the cross-section of the four fingers combined. This has the effect of introducing into the circuit a momentary resistance before the final break which checks the current flowing through the element 62 and thus reduces sparking at the break. This also prolongs the useful life of the fixed elements 52 and the movable elements 62.

I claim:

1. An electric switch comprising a barrier disc of insulating material, a pair of diametrically opposed fiat switch elements located in the margin of said disc and slightly thicker than the disc, the marginal portions of the disc between said pair of elements being continuous, a pair of metal strips extending across said disc on opposite sides thereof and rotatable together as a unit from simultaneous contact with said switch This is of great practical importance when elements into contact with the disc only, means securing said strips together, and means for rotating said strips about the disc axis.

2. An electric switch comprising a barrier disc of insulating material having a pair of spaced notches in the margin thereof, flat bronze switch elements located in said notches substantially flush with the disc, said elements being slightly thicker than the disc, a movable switch element `comprising two bronze strips on opposite sides switch elements slightlyy thicker than said disc an unfavorable effect-on the operation and wearl'ocated in said notches substantially flush with said disc, means supporting said switch elements independently of said barrier disc, a movable switch element comprising a hub member coaxial with the disc and a pair of strips of bronze secured to said hub and extending diametrically on opposite sides of said disc for simultaneous contact with said fixed elements, and means for rotating said movable member to move said strips into and out of contact with the fixed elements.

4. An electric switch comprising a barrier disc of insulating material, fixed fiat bronze switch elements slightly thicker than said disc located in the margin thereof at diametrically opposite points, a movable switch element comprising a hub member and two flat strips of bronze secured in opposed parallel relation to the hub member on opposite sides of the disc, said strips having end portions offset toward each other for simultaneous contact with said disc or said fixed elements, said end portions being slightly bent so that the opposed faces are parallel when in contact with the fixed elements. v

5. An electric switch comprising a barrier disc of insulating material having a central aperture, a pair of diametrically opposed notches in the margin and a series of small holes in the marginal portions between the notches, xed switch elements in said notches substantially flush with the faces of said disc, lubricating material in said small holes, a movable switch element comprising a hub member extending through said central aperture and two conducting strips secured to said hub member on opposite sides of said disc and extending diametrically for simultaneous contact with said fixed elements, and means for rotating said movable element.

6. An electric switch comprising a plurality of insulating discs with thick rims and central apertures, said rims being assembled to form a cylindrical housing wall, each said rim having a plurality of recesses on the inside thereof, a barrier plate of insulating material between each pair of said discs fitting within the rims thereof and having lugs projecting from its periphery to fit into said recesses and hold the plate in place, each said plate having a central aperture and a pair of diametrically opposed marginal notches, a. pair of flat switch elements supported by said discs in the notches of each said barrier plate and substantially flush with the plate, each said switch element being slightly thicker than the barrier plate, a movable switch element assembled with each barrier plate and comprising a hub member extending through the aperture in the plate and a pair of conducting strips secured to said hub on opposite sides of the plate, said strips extending diametrically for simultaneous contact with said xed elements, and a-lshaft extending through all said hub members and operable to rotate all the movable switch elements together.

7. In an electric switch a barrier disc of insulating material having a central aperture and a pair of diametrically opposedgarcuate notches in the margin thereof, at breit,v ejarcuate switch elements fitted into said notches substantially flush with said disc, a movable switch element comprising a hub member extending through said aperture and a flat diametrical conducting strip of bronze secured to said hub member and rotatable therewith into and out of contact with said arcuate elements, said conducting strip having longitudinal slots in both its end portions dividing said portions into parallel fingers adapted to act in succession in making or breaking Contact with said.arcuate elements when the movable element is rotated, and means for rotating said movable element.

8. In an electric switch, a barrier plate having a notch in the marginal edge thereof and a lubricant-holding recess in a face of said plate adjacent to said notch, a fixed switch element located in said notch with a contact surface substantially flush with said face of the plate, and a switch elem'ent movable on said face across said recess to receive lubricant and into contact with said fixed element.

HUGH W. BATCHELLER.

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

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