US2802912A - Hermetically sealed switch - Google Patents

Description

Aug- 1957- J. F. EDWARDS, JR.. :rm. 2,302,912

HERIETICALLY sumo svmca Filed Jan. 11, 1956 INVENTORS Johrc R Ed wards,Jr.

Lirzdsaq C.Frierzd. BY Kelmebh D. Shaub.

ATTORNEY 2,802,912 HERMETICALLY SEALED swrrcn John F. Edwards, Jr., and Lindsay C. Friend, Baltimore, and Kenneth D. Shaub, 'Iimonium, Md., assigno'rs to Bendix Aviation Corporation, Baltimore, Md., a corporation of Delaware Application January 11, 1956, Serial No. 558,554 6 claims. (Cl; 200- 14 This invention relates to switches of that type having electrical contacts located in a sealed enclosure. Such switches are used extensively in areas where explosive gases are or may be present, where it is desired to provide high resistance to arcing by evacuation of the switch chamber or by loading the latter with an inert gas, and in numerous other installations. Prior known switches of this general type are either more or less complicated and hence relatively expensive to manufacture, require a relatively high actuating force, or are sensitive to vibration and mechanical shock; and the primary object of the present invention is to provide a switch which will avoid these objectionable features.

Another object is to provide a switch of the hermetically sealed type which will accommodate practically any desired number of contacts and which at the same time may be set with remarkable ease and reliability.

The foregoing and other objects and advantages will become apparent in view of the following description taken in conjunction with the drawing, wherein:

Fig. 1 is a view in transverse vertical section of a switch in accordance with the invention;

Fig. illustrates the switch of Fig. 1 incorporated in a so-called wafer-type switch assembly; and

Fig. 3 is a plan view of the inner or contact side of the wobble end plate of the switch, illustrating a variation in the contact arrangement with respect to that shown in Figs. 1 and 2.

Referring to Fig. 1 of the drawing, a capsule is generally indicated at it is made up of a base or end plate 11, which may be made of substantially rigid material such as non-corrosive metal, insulation or the like, and has fixed therein a plurality of upstanding contacts 12, 13, etc., which are imbedded in suitable insulating material 14 and provided with leads as indicated at 15. The opposite end plate, indicated at 16, functions as a wobble switch c-ontactor; in the example illustrated in Figs. 1 and 2, it is made of conducting material such as copper and has substantially centrally thereof a cam depression 17, the said plate 16 being connected to the base plate 11 by a bellows portion 18, made of spring material embodying sufiicient spring force to draw the plates 11 and 16toward one another to a position where the lowermost portion of the cam depression 17 bottoms on the plate 11. The spring strength of the bellows portion 18 may vary, depending upon the installation to which the switch is adapted. For example, if the switch is used for high altitude service, the spring force of the bellows 18 should be sufiicien-t to maintain the base in contact with the inner end of the cam portion 17 at the lowest external pressure to which the switch may be subjected. Obviously, the biasing effect of the spring force is substantially uniform on all sides of the bellows.

An actuator or set-ting cam is indicated at 19; it has an eccentric contour and is provided with .a control shaft 20. When this cam is inserted in the cam depression 17 and rotated, the wobble plate 16 may be selectively rocked 2 into contact with any one or more of the contacts 12 and 13.

In the wafer switch assembly of Fig. 2, parts which correspond to those of Fig. l are given like reference numerals. In this instance the base is indicated at 11; it is slightly modified in that it is extended at diametrically opposite points and connected by insulated posts 21 to an index plate 22. Obviously, if the outer anchor portion ofthe base 11' is made of insulation material,

the posts need not be insulated. The cam 19 and shaft 20 in this instance are conductors, the shaft being extended upwardly and connected through a key section 23 to a coupling member 24, which in turn projects through a bushing 24 and has fixed to the end thereof an adjusting knob 25. The section 23 is keyed to a rotatable switch plate 26, carrying wiper blades 27, adapted to wipe a series of spring contacts '28, secured to an intermediate plate 29. The index plate 22 is provided with a series of detent depressions 30 on its under surface, which are adapted to be engaged by one or more detent members 31, mounted on spring strips or arms 32, which are fixed to the coupling member 24 and hence rotate with the latter.

The construction and operation of wafer switches are well known, the novel feature of the assembly shown in Figure 2 being the switch of Fig. 1. To set the switch, the selector knob 25 is rotated to index any one or more of the circuits (not shown) which may be interconnected through the said switch. As the knob is rotated, it also imparts rotation to the cam 19, which rocks the wobble plate or cap 16 into engagement with certain of the contacts 12, 13, etc.

In cases where the switch is to be mounted in an area of explosive gases, the capsule or switch proper of Fig. 1 may be located directly in such area and the actuating cam rendered accessible for remote control, or as in the installation of Fig. 2, the high voltage circuit may be interconnected through the switch proper and the low voltage or relay circuitry by way of the contacts 27 and 28. The switch capsule may be readily evacuated or loaded with an inert gas; it can easily be designed to resist vibration, acceleration and gravity forces, and its very simplicity is one of its most important advantages.

In Fig. 3 the wobble plate or cap, here indicated at 16, is made of insulated material and is provided with a series of contact strips 33, adapted to engage any selected number of the contacts 12, 13, etc. of the plate 11 of Fig. 1, which in this instance would be arranged in arcuate groups. This serves to illustrate how the switch of Fig. 1 may be conveniently adapted to different switch circuitry.

In other installations, the wobble cap could be provided with circuit connections direct to selected groups of contacts. These and other adaptations will be obvious to those working in the electrical arts once the basic concept of the invention becomes known.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a switch of the type specified, a capsule made up of opposite end plates connected by a bellows portion comprised of spring material tending to urge the said plates toward one another, one of said end plates serving as a movable contact plate and carrying a member which projects through the chamber defined by the capsule and engages the opposite end plate to provide a fulcrum or pivot point about which said movable contact plate is rockable, the other of said end plates having a plurality of contacts projecting therefrom into said chamber, and means for actuating said movable contact plate about its fulcrum or pivot point to make and break one or more electrical circuits which may be interconnected by way of said contact plate and contacts.

2. In a switch of the type specified, a capsule made up of opposite end plates joined by a bellows portion of spring material tending to move said plates toward one another, one of said plates being provided with a plurality of contacts projecting therefrom into the chamber defined by the capsule and the opposite end plate serving as a movable contact member, said movable end plate being provided with a projection which extends through the chamber and engages the opposite end plate to provide a rocking or fulcrum point, and cam means rotatable to rock said conductive end plate about its fulcrum or pivot to make and break one or more electrical circuits which may be interconnected by way of said contact plate and contacts.

3. An hermetically sealed switch comprising a capsule made up of opposite end plates joined by a bellows portion Ofspring material tending to move said plates toward one another, one of said plates being fixed in a definite switch position and provided with a plurality of contacts projecting therefrom into the chamber defined by the capsule and the opposite end plate serving as a movable contact member, said movable end plate being formed with a substantially central depression the innermost point of which engages the relatively fixed end plate to provide a pivot point, and rotatable cam means adapted to rock the movable plate about its pivot to make and break one or more electrical circuits which may be interconnected by way of said contact plate and contacts, said bellows portion having sufficient spring force to maintain contact between the relatively-fixed end plate and the innermost point of said cam depression. 4. An hermetically sealed switch comprising a capsule made up of opposite .end plates joined by a bellows por: tion of spring material tending to move said plates toward one another, one of said end plates being substantially rigid and fixed in a definite switch position and having a plurality of contacts projecting therefrom into the chamber defined by the capsule and the opposite end plate being movable and carrying conductive material for engagement with said contacts, said movable end plate being formed with a substantially central depression which extends through the chamber and has its innermost point engaging the rigid end plate to provide a rocking or fulcrum point, and a rotatable eccentric cam adapted to engage in said depression.

' 5. An hermetically sealed switch comprising a capsule made up of opposite end plates connected by a bellows portion of spring material tending to move said plates toward one another, means supporting one of said end plates in a definite fixed switch position, a plurality of contacts projecting upwardly from the fixed end plate into the chamber defined by the capsule, the end plate opposite said fixed plate being free to wobble and carrying conductive material for engagement with said con-v tacts, said wobble end plate being provided with a substantially central pivot member which extends through the chamber and has its innermost point engaging the rigid end plate, a rotatable eccentric cam engaging'in said depression, a-shaft projecting from said cam,-and switch-indexing means associated with said shaft for rotating the latter.

6. An hermetically sealed switch comprising a capsule made up of opposite end plates, side walls connecting said plates and formed-at least in part of collapsible material, one of said plates being fixed in a definite switch position and the other of said plates serving as a movable wobble plate, contacts projecting from one of said plates and adapted to coact with contact elements carried by the other of said plates, means resiliently biasing the said plates towards one another, said biasing means exerting a substantially uniform biasing force on all sides of the capsule, a member projecting from the movable contact plate axially through the chamber defined by the capsule and engaging the opposite end plate to provide a fulcrum or pivot point about which said movable contact plate has universal wobble movement, and means for. actuating said movable contact plate about the fulcrum or pivot point provided by said member to make and break one or more electrical circuits which may be interconnectedby said contacts.

References Cited in the file of this patent I UNITED STATES PATENTS

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