US2060813A - Mercury tube switch - Google Patents

Description

Nov. 17, 1936. c. H. LARsoN MERCURY TUBE SWITCH Filed April 24, 1935 (bm-@WW M3071/ I,

Patented Nov. 17, 1936 PATENT oFFlcE MERCURY TUBE SWITCH` Carl H. Larson, Elkhart, Ind., assigner to The Adlake Company, a corporation of Illinois Application. April 24, 1935, Serial No. 17,9%

'l Claims. (Cl. flitumilil This invention relates to mercury tube switches in which the level of the mercury is determined by the position of a displacer and that is dependent upon a magnetic core in the tube sub= ject to a magnet and the principal object is to make it easy to inspect the electrodes and their relation to the mercury while assembling the switch, and when it is in service. This is achieved by using a very buoyant and transparent displacer of glass, for example assembling, carrying a magnetic core above the parts to be seen. Incidentally, this keeps the metal of the 'core from affecting the mercury and contributes .to other advantages which will appear as the description is read in connection with the accom" panying drawing, in which Fig. l is a vertical section through one :form oi power'transier switch embodying the invention, with the parts shown in the position they assume when the magnet is def-energized and the displacer is iioating in the mercury;

Fig. 2 is a section of the same switch with the parts in the position they assume when the 4magnet is energized and the displacer is lifted;

Fig. 3 is a perspective view oi the displacer and the magnetic core;

i Figs. 4, 5 and 6 are views similar to Figs. 1, 2 and 3, but disclosing a diferent form of power transier switch embodying the invention.

l3nt this drawing and the description are used for the purpose of disclosure only, and others will be able to make different forms and apply various features of the invention to use in other switches.

Thev mercury switch includes a glass tube or envelope Ill, pinch sealed at the bottom Il and sealed ofi at the top I2, after being given a charge of mercury I3 and a suitable gas iill, such as helium, 'helium hydride, hydrogen, etc.

Three conductors, I4, I5 and I6, are sealed through the bottom, and the last two are insulated from the mercury by sleeves IIl and I8, diierent heights beyond which they are exposed.

The displacer is a transparent tube I9 which,

in this power transfer switch, takes the form of an inverted test tube, or thimble, having a closedupper end and a wide open lower end 2|, the latter receiving the conductor I5 and sleeve II in the position shown in Fig. 1.

The magnetic core, or armature 22, of some ferrous material is a hollow cylinder having rounded hardened steel guides 23 pressed into- The core is preferably made of exceptionally pure iron, such as, for example, Svea metal, sold in the United States by the Swedish iron and Steel Company, of New York, but oi course other ferrous material will-be selected to suit conditions of service.

A spring til of piano wire, coated with imagu netic oxide of iron, or degassed pure iron, is screwed into the bore 25 of the core and has several turns 26 close together to bind it securely in the core. The upper portion of the core is counter-bored at 2l, and the spring 24 projects bey-ond the upper end to prevent the core from striking the top portion It? ci the glass envelope while the switch is being shipped or handled.

another coil springA 2li extends across the bottom oi the tube ill about the sleeve il, and acts as a cushion for the lower end 2l of the displacer tube is.

The lower end of the core 2i has a reduced hollow nipple into which the upper closed end 20 of the displacer is inserted. Ordinarily the friction of a slight taper will be suicient to maintain the assembly, but the tube may be cemented in place with silica, if desired.

In order to permit mercury to escape from the bore of the armature after the switch has been on its side, diagonal cuts 30 are made in the armature with a milling cutter, beginning at about the juncture of the nipple 29 with the main body of the armature.

l Should the armature be made split, as is sometimes done for use with alternating current, the cuts may be omitted.

The electromagnet associated with the Switch includes a coil 3l, a laminated yoke 32, preferably of Allegheny transformer steel, and pole sleeves 33 of pure soft iron, such as Svea metal, held in place by iron clamps 34.

The mercury tube switch is adjustably held within the core by a split ring 35 of. spring brass located between the adjacent ends of the pole sleeves 33, and frictionally holding the glass tube Ill.

VThe displacer I9, being transparent from the lower end of the nipple 29 to the bottom 2|, the height of the charge of mercury in relation to the electrodes formed by the exposed end of the conductors I-I and I5, can be adjusted by sight during the assembly operation, and afterwards in use the electrodes and the height of the mercury can be inspected at any time by direct vision.

The displacer should be made of heat resisting glass of which there are a numberon the market known as boro-silicate glass, Pyrex, etc., or where the cost will permit, it may be made of. quartz.

In Fig. 1 thev displacer, trapping gas within it, forces the mercury away from the exposed end of the conductors I5 and raises the level above the sleeve I9 and closes the circuit between the conductor Il and the exposed end of the conductor I6.

Upon the magnet being energized, the armature lifts the displacer to about the position shown in Fig. 2, the mercury rises about the exposed end of the conductor I5 and falls below the exposed end of the conductor I6, thereby opening the circuit from the conductor or to the conductor I6, and closing the circuit from the conductor I5 to the conductor I4. i

Such switches are used to transfer from one source of power to another and, of course, the one circuit must be broken before the other circuit is closed. That is easily accomplished with the switches here disclosed and at the same time the volumes are reduced to such a small extent that very little power is used to operate the switch.

As an example of dimensions, one form of switch that has been found satisfactory has a tube I0, 138 mm. long, 151/2 to 16 mm. inside diameter. The conductor I5 extends 27 mm. above the bottom of the tube at the inside and is exposed for a length oi 5 mm. and the conductor I6 extends 34 mm. above the bottom of the tube and is also exposed for 5 mm.

'I'he armature is 1H inches long, f1; inches inside diameter, and the counter bore is 1/2 inch in diameter for a depth of. H inches. Other dimensions are in proportion.

In the form shown in Figs. 4, 5 and 6, a glass tube, or envelope 36, is similar to the glass tube III, except that it has a lateral enlargement 31 at the bottom to provide space for the conductor I5 by which means a relatively small tube serves for a three-electrode switch, and provides ample clearance for all parts. I

'I'he displacer tube, or thimble, 38, is longe than the tube I9, and the core, or armature 39, is a split sleeve telescoped over the displacer and provided with fingers 40 at its ends, making contact with the outer surface of the tube, or being spaced from it very slightly.

A spring 4I of degassed pure iron rits tightly over the upper end ot the thimble 38, and the tips of the fingers 4I) are wedged between the adjacent convolutions Vof the coil.

In assembly the armature and the spring are gotten into the position shown in the drawing by a threading movement, the displacer tube is inserted from below and pressed upwardly while being turned, which has the effect of threading the coil onto it, where it remains securely by the y clamping friction.

When the magnet is de-energized the parts assume the position shown in Fig. 4, the displacer forcing the mercury away from the exposed end of the conductor I5 before it rises to cover the exposed end of the conductor IB.

When the magnet is energized, the parts assume the position shown in Fig. 5, the circuit from the conductor I4 to the conductor I6 being rst broken and then the circuit from conductor I 4 to conductor I5 closed.

It will be obvious to those skilled in the art that the construction here illustrated provides the necessary clearances with a minimum volurne of mercury and a very small power consumption.

For alternating current service, the armature 39 is cold rolled steel, case hardened Vand ground or some similar material whereby the armature requires no guide and can be gotten very close to the magnet. For direct current service, soft iron should be used and guides provided, as explained in the co-pending application of Gehrand and Larson, led April 18, 1935, Serial Number 17,053.

I claim as my invention:-

1. In a. mercury tube switch, a tube, a conductor sealed through the bottom of the tube and provided with an electrode within the tube, mercury in the tube to co-operate with the electrode, a hollow transparent displacer cooperating with the mercury and adapted to cover the electrode and a hollow magnetic core carried by the displacer and arranged so that a side view of the electrode is possible through the transparent displacer.

2. Ina mercury tube switch, a tube, a conductor sealed through the bottom of the tube and provided with an electrode within the tube, mercury in the tube to co-operate with the electrode, a tubular displacer substantially closed at its upper end adapted to telescope over the electrodeA ing one of the conductors for a space above the bottom of the tube, a tubular displacer closed at its upper end and aligned with the last mentioned conductor whereby in one position it will displace mercury from that conductor, and a magnetic core borne by the displacer at all times above the mercury level.

4. In a mercury tube switch, a tube, conductors sealed through the bottom of the tube, mercury in the tube, an insulating sleeve surrounding each of the two conductors for a distance above the bottom of the tube, a transparent tubular displacer having a pocket open at its bottom and adapted in one position to displace mercury from one of the conductors and a. magnetic core carried by the displacer above the mercury level.

5. In a mercury tube switch, a tube, mercury therein, conductors sealed through the tube for co-operation with the mercury, a tubular displacer open at its bottom to the mercury and closed above, and a magnetic core carried by the displacer above the mercury.

6. In a mercury tube switch, a tube, mercury therein, conductors sealed through the tube for co-operation with the mercury, a displacer cornprising a glass tube closed at the top and open at the bottom to trap gas above the mercury, and a magnetic core fixed to the displacer above the mercury.

'7. In a mercury tube switch, a tube. conductors sealed through the bottom oi' the tube, mercury in the tube, an insulating sleeve surrounding one of the conductors for a distance above the bottom of the tube, a transparent tubular displacer open at its bottom and adapted to telescope over said one conductor, and a magnetic core carried by the displacer above the mercury level.

CARL H. LARSON.

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