US2273921A - Interrupter - Google Patents

Description

G. BAIN INTERRUPTER Filed Nov. 4, 1946 Srwentor 65e/qa @ma Gttornegs Feb. 24, 1942.

Patented Feb. 24, 1942 IN TERRUPTER George Bain, Owensboro, Ky., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Anuman Novemberl; 1940, serial No. 364,161

4 Claims.

This invention relates te circuit interrupters and more specifically to mercury interrupters which operate automatically when connected to a source of power to make and break a circuit to provide pulsating current therein. This general type of mercury interrupter is one ln which there is provided a small contact area of carbon or some similar material having a higher resistance to the flow of electrical current than mercury. This surface is.in contact with a small body of mercury, the two bodies being connected in series in an electrical circuit with a current flowing therethrough such as the type of interrupter disclosed in U. S. Patents No. 2,107,742, issued to Samuel Ruben.

In the operation of this type of interrupter the flow of current in the material having the higher resistance to the mercury causes an intense heating of the mercury in contact with the surface and the mercury in this region vaporizes causing the current to cease flowing and therefore a cessation of the generation of any further mercury vapor. The vapor that has been formed recondenses allowing the mercury to again contact the surface and the same cycle is reproduced. This causes a series of makes and breaks in the electrical circuit and the result obtainable is a pulsating direct current. In most of the devices of this type the enclosure within which the liquid mercury is contained has a space above the mercury into which the same may expand and when the devices are used as a source of supply for the various accessories, say, for example, on an automobile wherelthere is a certain vibration attendant the operation thereof, there are times at which the mercury bounces or is jarred away from the carbon or similar surface to cause a mechanical break in addition to the normal thermal breaks as caused by the operation of the device. This, therefore, interferes with the normal regular operation of the device and causes the current to be suspended for an undue length of time and to contain irregularities which are not satisfactory from a viewpoint of current supply.

It is therefore an object of my invention to provide means to prevent such jarring away from the normal contact surfaces and to provide an interrupter which will give an even flow of pulsating current regardless of the mechanical vibrations to which the device is subjected.

With this and other objects in view, the embodiment of my invention will be best understood by reference to the following specification 66 and claims and illustrations in drawing, in which:

Figure 1 shows a vertical section through an interrupter incorporating my invention;

Figure 2 shows a partial vertical section through the actual interrupting surfaces of the device; and

Figure 3 is a sectional view taken on line 3 3 of Figure 1.

Referring now more specifically to the drawing, there is shown in Figure l a long cylindrical envelope 2 which is made of glass or some other suitable insulator. Sealed in the upper end thereof is an electrode 4 which extends down into the central cavity for a substantial distance. Mounted in the lower end of the cavity and rigidly secured therein is a circular ceramic disc 6 having'a central opening B therein in which is supported a small block I0 of carbon or other suitable resistance material. Into the small block of carbon there is secured a second electrode I2 which is sealed into the end of the glass container and connected into an input cable I4. A body of mercury i6 is housed within the hollow container and is of sufficient quantity to extend from the ceramic disc 6 up to a substantial disthe accompanying tance on the upper electrode 4, thus completing the circuit between the electrode 4 and the carbon block I0.

In the normal operation of the device which would be operated in its vertically shown position or a position relatively close thereto, the two electrodes are connected to a source of power and current flows from electrode l2 to the car- ;y bon button I0 through the mercury to the electrode 4. This flow of current causes a very high current density in the carbon block i0 and considerable heating of the mercury on the upper surface. This is of a sufficient amount to vaporize the mercury at this point and mercury vapor expands and pushes away the adjacent mercury to form a small bubble such as shown at I8 in Figure 2. This breaks the electricalcircuit but the mercury vapor may recondense to again touch the upper surface of the block Il), reforming the circuit. The cycle is immediately repeated and a pulsating current is obtained therefrom.

One of the uses of this type of interrupter would be to supply a high voltage from an ordinary six volt storage battery to supply various accessories used on cars and in mounting such a device for operation upon a car the same would be subject to road shock and vibration and in many instances this vibration would be suillcient to cause the body of mercury Il to jar up away from the carbon block Il and the circuit would then be mechanically broken and not thermally.

This interferes with the ordinary operation of the device and I therefore provide a long metal sleeve 20 having a central bore 22 larger than the outer diameter of the electrode 4 so that this metal sleeve may slide up and down freely on the center electrode. The lower surface 24 of this sleeve sits upon the upper surface of the mercury I8 and thus tends to hold it down upon the carbon block and in essence provides a mechanical damper to prevent road shock or other vibrations from interfering with the normal operation of the interrupter thermally. It has been found that the addition of this mechanical damper assists greatly in preventing the mercury from jumping from the surface of the lower electrode and maintains it in contact at substantially all times.

I claim:

1. In an interrupter, an insulating casing, a block of material of higher resistance than mercury supported in one end thereof, an electrode connected thereto, a body of mercury' within the casing and resting upon one face of the block, a second electrode supported by the casing extending into the mercury and means on the upper surface of the mercury to maintain the latter in contact with the resistance material.

2. In an interrupier. a cylindrical casing of insulatingmateriaLacarbonmasssupportedin one end thereof, an electrode connected thereto. abodyofmercuryinthecasingadapiedwrest upon the mass, a second electrode supported by the casing extending into the mercury, and a member floating upon the upper surface of the mercury to maintain the same in contact with the carbon man.

3.Inaninterrupter,aninsulatingcasing,a block of carbon mmmted in one end thereof, an electrode connected thereto, a body of mercury within the casing and resting upon the carbon, a second electrode supported by the casing extending into the mercury and a member of appreciable weight floating on the upper surface of the mercury within the casing to maintain the mercury in contact with the carbon.

4. In an interrupter, a cylindrical glass casing, a block of carbon supported in one end of the casing, an electrode connected thereto, a second electrode supported in the oppomte end oi the casing and extending through the center thereof to a position above the carbon, a body of mercury within the casing and resting upon the carbon and extending up so that the second electrode is immersed therein and a weight slidably mounted on the second electrode and seated upon the upper surface of the mercury to maintain it in contact with the carbon surface.

GEORGE BAIN.

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