US2216449A - Mercury switch and support therefor - Google Patents

Description

Get. 1. 9- c. B. MOORE ET AL MERCURY SWITCH AND SUPPORT THEREFOR Filed April 9, 1958 26 FIG.

INVEN TOR. COLEMAN B. MOORE EDWIN C. BURDICK MEWM Patented Oct. 1, 1940 UNITED STATES PATENT OFFICE LIERCURY SWITCH AND SUPPORT .THEREFOR Application April 9, 1938, Serial No. 201,104 2 Claims. (Cl. 200-32) This invention relates to electrical switches, and more particularly those known in the art as mercury switches and operating means therefor. r

Switches of this type comprise an hermetically sealed envelope of glass, contacts sealed therein, and a body of mercury movable in the envelope -so that upon movement thereof, the mercury will bridge the contacts and complete an electric circuit. In the usual form of switch of this type, it has not been possible to obtain any large number of sets of contacts so that by tilting the switch into various positions, only a few circuits could be closed or opened. In some uses of a 5 mercury switch, it is desirable to have a large number of pairs of contacts and to be able to continuously bridge them by the mercury in sequence.

It is therefore an object'of our invention to go provide the combination of a mercury switch with any number of contacts in it corresponding with the number of circuits to be closed with a movable support for the switch which will permit it to be tilted into a number of nonparallel planes to successively close the contacts.

Our switch consists of a glass envelope of toroidal form having pairs of contacts inserted therein at suitable intervals around its circum ference. A body of mercury is placed in the 0 envelope, and as it is tilted on its special support to difierent positions, the electrodes will be successively bridged by the mercury.

The various features of novelty which characterize our invention are pointed out with partic- 5 ularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects obtained with its use, reference should be had to the accompanying 4o drawing and descriptive matter in which we have illustrated and described a preferred embodiment of the invention.

In the drawing:

Fig. 1 is a front view of one embodiment of the invention showing the switch and its supporting mechanism;

Fig. 2 is a view from the right of Fig. 1 with vals pairs of contacts a,b, c and d. These contacts are sealed within the wall of the tube 4 in any suitablepmanner, and the inner ends thereof extend nearly to the opposite wall of the tube. The outer end of the pairs of contacts 5 are to be attached to conductors and may be joined in a single cable or not as desired. Within the tube 4 is a globule of mercury 5, which, as more clearly shown in Fig. 2, is adapted to bridge the contacts of each pair to close a circuit f 10- which they are apart. As the tube 4 is progressively tilted, the mercury 5 will successively bridge the pairs of contacts to close the circuits of which they form a part. Although, for purposes of description, we have shown only four 1 pairs of contacts, it will be obvious that any desired numben of pairs of contacts may be inserted within the tube 4, so that any desired number of circuits may be successively closed. The only limitation to the number of pairs of go contacts is that they should be far enough apart so that the mercury 5 will not bridge more than one pair at a time, unless it is' desired to have more than one circuit closed at once. By varying the size of the tube 4, a larger or smaller 95 number of contacts may be accommodated.

If the switch is rotated in order to close the contacts, the wires leading therefrom will soon become so twisted that the device would be rendered useless. In order to obviate this difiiculty, so the switch should be progressively tilted about its center while restraining it from rotation.

A support for the switch and a means for tilting it will now be described. 7

The supporting and tilting mechanism may be 35 mounted upon some stationary object such as the part 6 which has mounted on it, as by a screw, two angle members I and 8, the former of which has attached to it a journal 9 through which a driving shaft is adapted to extend. Extending through the journal 9' is a shaft I0 which has integral therewith on its lower end a gear,

' II that is driven, preferably at a constant speed,

from a gear I 2 rotating with a power shaft l3. The upper part of the shaft III has a collar l4 5 attached to it, and the collar supports for rotation therewith an angularly shaped arm I5 whose upper end is bent over as shown at I6 and is provided with a pair of spaced rollers H.

A support for the switch proper is mounted on 59 the upper end of shaft ID for universal movement therearound. To this end, the tip of shaft III is spherical as shown at l8. A switch supporting member I!) is provided with a groove or depression 20 near its periphery in which the tube 4 is adapted to be placed and is provided at its center with a conical opening 2| that will permit it to be drawn up against, but not over the sphere I8. Cooperating with the support I! is a member 22 having a cup-shaped depression 23 to be placed over the sphere l8 and fastened, as by screws, tothe support IS. A bearing that is capable of universal movement about the sphere I0 is thus provided by the opening 2| in support l9, and the depression 23 of member 22 and the switch tube 4, which is clamped in place on the support l9 by a curved finger 24, may be moved around the shaft I0 into practically any plane. The member 22 is cut away as indicated at 22a so that it may be placed in position without interfering with the contacts 0.

In order to tilt the switch, the support is is provided at its periphery with a lip 25 that is received between the rollers I! on the arm l5. Rotation of the switch during its tilting movement is prevented by an extension 26 of the member 22 bearing against the side of an elongated opening 2'! in angle member 8.

In its operation, the saft l3 will rotate shaft I0 and arm l5 carrying the rollers l'l. As the rollers I] move through their path, they will progressively tilt the support l9 and switch 4 around sphere l8 as a center, the extension 28 bearing against one edge of slot 21 to prevent rotation thereof. 'I'heposition assumed by the switch and its supporting parts after arm I5 has rotated through 180 is shown by the dot'and dash lines in Fig. 2. It will be seen that at this time contacts c at the lowest portion of the tube 4 will be bridged by the glob-ule of mercury 5. Inasmuch as the switch is tilted, rather than rotated, the leads to the pairs of contacts therein will merely flex to follow the movements of the contacts, rather than be twisted.

Another embodiment of the invention is disclosed in Fig. 3 wherein there is shown another manner of inserting the contacts in the envelope and another type of holder for tilting the switch. In this embodiment, an envelope 28, also of toroidal shape, has a series of contacts e, ,"f inserted in the tube around its circumference. In

.this form, however, instead of having pairs of contacts, there is a single contact individual to each circuit which the switch is adapted to control and a contact g common to all of the circuits. In this manner, as the switch is tilted, the globule of mercury 5 will successively bridge the contacts e and f with contact g. By the use of a single contact for each circuit and a common contact. for all of the circuits, the number of leads that it is necessary to take from the switch is considerably reduced, particularly if the switch is used for a large number of circuits.

As is shown in Fig. 3, a spring clip 29 having ends 30 is used to hold, in this case, two of the switches in place for simultaneous actuation. The clip 29 is attached at one side to a stud shaft 3| which is mounted for rotation in a bushing 32, and has attached to its other side a flexible shaft 33, which is in turn fastened against rotation on a bracket 34 that is mounted on the able.

switches may conveniently be tied in about they flexible shaft 33 so that they merely flex as the switches are tilted.

Inthe operation of this switch, rotation of shaft 35 will rotate the shaft 38 and its arm 39 to move bushin 32 around shaft 38 as a center. Because of the fact that the axes of the switches 28 are perpendicular to the bushing 32, they will at all times be tilted as shown as the bushing is rotated, but they will be restrained from rotation about their own axis by the flexible shaft 33. Therefore, as the arm 39 and bracket 32 are rotated, the switches will be progressively tilted, and the mercury 5, remaining at the bottom of the envelopes 28 will successively bridge the contacts e and f with the common contact g. It will be obvious in this embodiment of the invention, as it was in that of Figs. 1 and 2, that any desired number of contacts may be inserted in the switch is subjected to particular rough usage,

it may be desirable to have the envelope made of a more rugged material. For such usage, a switch of the type shown in Fig. 4, in which the envelope 42 is made of metal tubing in toroidal form, may be more suitable. A plurality of contacts 43 is then inserted within the envelope and insulated therefrom by glass or other non-conducting material in the form of beads 44. With aswitch of this type, the envelope 42 acts as one of the contacts and, for this purpose, has a conductor 45 attached thereto. As the switch is tilted, the body of mercury 5 within the envelope successively'bridges it and the various contacts 43 to complete the circuits of which they are a part.

The present novel switch and its support satisfy a long-felt need in the art and as is readily seen, they may be used in almost any application in. which a multipleswitch of this type is desir- One of the many uses to which a switch of this type may be applied is as a selector switch in multiple potentiometric instruments, wherein it is used to successively connect the instrument with a plurality of thermoelectric elements.

It is noted that in the embodiment of Fig. 1 the switch is tilted about a point that is on the axis of generation of the envelope and at a point substantially midway between planes extending adjacent the upper and lower surfaces of the envelope. tilted about a point that is on their axis of generation and substantially on a. plane extending between the envelopes or midway between the upper and lower extremities thereof. Since the tilting of more than one envelope merely permits more contacts to be simultaneously closed; a plurality of envelopes forming a switch may be moved in unison by a single support and for the purposes of this invention may be considered a single switch. Mounting the switch for movement around this point permits the switch to tilt in the smallest possible space, which is of great importance when it is being used in an instrument casing.

While in accordance with the provisions of the statutes, we have illustrated and described the In Fig. 3 the two envelopes shown are amaaae best form of our invention now known to us, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of our invention as set forth in the appended claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features.

Having now described our inventionQwhat we claim as new and desire to secure by Letters Patent is:

1. In combination, a rotating shaft having a spherical end, a support mounted for universal movement on said sphere, means to prevent said support from rotating, an ,arm attached to said shaft for rotation therewith and having means engaging said support whereby as said arm rotates said support will be progressively tilted in a plurality of planes, and a switch mounted on said support.

2. In combination, a mercury switch in the form of an endless tube, a plurality of contacts extending from said tube, a support for said tube, a flexible shaft attached at one end to said support and at its other end to a stationary object, an angular arm upon which said support is retatably mounted, and' means to move said arm through a circular path, said shaft preventing rotation of said support as said arm is moved.

7 COLEMAN B. MOORE. EDWIN c. BURDICK.

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