US1743067A - Mercury switch - Google Patents

Description

Jan' 7, 1930 w. R. WALKER MERCURY SWITCH Fiied sepa-18, 1928 R v. m im fm f/ l@ A Patented Jan. 7, 1930 UNITED STATES PATENT OFFICE WARREN R. WALKER, F SHORT HILLS, NEW JERSEY, ASSIGNOR TO COOPER HEWITT ELECTRIC COMPANY, 0F HOBOKEN, 'NEW JERSEY, A CORPORATION OF NEW JERSEY MERCURY SWITCH Application filed September 18, 192,8.v Serial No. 300,626.

The present invention relates to switches, and particularly to that type of switch in which mercury is used to make and break the circuit between two terminals within a closed envelope.

creasing the cost of such switches in that cheaper glass, lead-in and electrode material can be used -in the production of my new switches, such material also being more easily worked. Other objects will be obvious from an inspection of the accompanying speciiication and drawings.

The invention consists in the novel arrangement and combination of parts, as hereinaftor set forth and claimed.

Heretofore it has been usual to provide envelopes of hard glass, which were necessary to withstand the heat produced by the arc which occurs when a circuit is opened while carrying a relatively large current such as or 25 amperes, at 110 volts. By the introduction of suitable shields and baiiles of hard glass, quartz, porcelain, or the like according to the present invention it is possible to use a soft glass envelope with safety, al-

3 though such an envelope without the bailie cannot safely rupture much over 5 amperes.

I have discovered that switches of the type disclosed herein and in my Patent 1,67 6.7 54 issued July 10, 1928 on an application filed June 17, 1925, the present application being for improvements thereon, possess the property of safely making and breaking when tilted or rotated circuits carrying 50 to 75 amperes, and when the improvements of my above referred to patent and of this application are embodied in a switch of the type disclosed in the Mailey Patent 1,537,921 is sued May 12, 1925 and of the type disclosed in British Patent 183,683 circuits of greater amperage-can be safely made and broken, and

the added cost of production of the switch will be offset by the greater current breaking property of the switch in continuous commerclal use as compared with the amperages which hard or soft glass devices described in the patents above referred to willsuccessfully make and break in commercial practice.

For the purpose of. illustration several switches embodying the invention are shown in' the accompanying drawings, in which Fig. 1 is a longitudinal cross section of a switch embodying the invention,

Fig. 2 is a plan view of the bale shown in Fig. 1, l Fig. 3 is a front view vof the same baiiie,

Fig. 4 is an end view thereof,

Fig. 5 is acentral vertical section, with the baiile shown in elevation, of a modification of Fig. 1 for larger current capacity,

Fig. 6 is a similar view to Fig. 5 of a switch of different design but embodying the invention, and v Fig. 7 is a longitudinal cross section with the interior shield in elevation of a modication of Fig. 6 for larger current capacity.

In all the figures the envelope is preferv ably formed of a soft glass, and may be either evacuated or filled with hydrogen, ammonia, nitrogen or other inert gas, in a manner well known to those skilled in the art. A filling of hydrogen or ammonia is, however, preferred. The inleads are preferably formed of dumet, which is a nickel steel wire coated with copper, and specially designed for sealing into soft glass but may be of any other material having a suitable coeiiicient of expansion. Sincethe copper would impair the action of the mercury, the portion of said inleads which `project within the envelope are preferably formed either of nickel previously welded to the dumet, or of nickel steel, exposed by removing the copper coating from the dumet inside the container wallu although other metals may be used without departing from this invention. The shields or barriers used in the various figures are either blown or l molded from hard glass, quartz, porcelain. or any suitable vrefractory material, and are inserted within the envelopes before the ends of said envelopes are closed.

With .particular reference to Fi s. 1, 2, 3, 4 and 5 envelope 1 is of tubular s ape with closed ends. An inlead 2 of dumet enters said envelopev 1 through a reentrant seal 3 in the top of said envelope and a little toward one end thereof. A similar inlead 5 enters said envelope 1 through a reentrant seal 6 in the top of said envelope and adjacent to *he end more distant from inlead 2. A re-l fractory shield or baille 8, which is boatlike in shape, is located within said envelope 1 at the bottom thereof, with one end adjacent to the end of said envelope l1 which isnearer inlead 2, and with the other end of said shield 8 terminating near said inlead 5. A central depression 9 in shield 8 into which inlead 2 projects has an annular projection 10 extending upward from the bottom thereof which engages with said inlead 2 whereby said shield 8 is fixed in its position within said envelope 1. A longitudinal channel 11 which is somewhat more shallow than depression 9 and which is centrally disposed in the upper surface of shield 8 extends from the depression 9 to the end of said shield 8 adjacent to inlead 5. Mercury is provided in said envelope to a level slightly below the bottom of said channel 11 when the switch is in the open position, as shown, and is thus divided into a pool 12 within the shield 8 in contact with inlead 2 and a pool 13 surrounding said shield and in contact with inlead 5. When the envelope is tipped slightly so as to tend to elevate pool 12 above pool 13 the mercury in pool 12 will run throu h channel 11 and unite the two pools, thus c osing the circuit from inlead 2 to inlead 5. When the envelope is restored to the level position illustrated, the mercury will run in the reverse direction through channel 11 until the bottom of channel 11 at the point where it opens into depresfsion 9 is at the same lever as the mercury,

when the mrecury will thereby again be separated into the two pools 12 and 13, and the arc will form betwen the two pools at that point. It will thus be seen that the arc is substantially conned to the depression 9 and the channel 11 where the arc resisting shield 8 is effective in protecting the soft glass envelope from the heat thereof.

The switch illustrated in Fig. 5 is designed for larger currents than that of Figs. 1, 2, 3 and 4, and in addition to being somewhat larger has an additional protection for the soft glass envelope. A tubular liner 15 of quartz, hard glass or other refractory material is provided for the envelope 1 and extoward the opposite end of said envelope 21.

A similar inlead 25 enters said envelope 21 at the bottom of the end opposite to seal 23 through the reentrant seal 26 and is curved so as to extend toward inlead 22. An arc shield 28 of hard glass, quartz orother refractory material is substantially tubular in shape,

with a bend toward one end thereof, said bent end opening upward to receive the inlead 22 and a portion of seal 23. At said bent end shield 28 is supported on the .bottom of envelope 21, while at the opposite end a curved bracket 29 of nickel or nickel steel welded to said inlead 25 holds that end of said shield' 28 firmly against the top of said envelope 21, the tubular shield 28 being of such diameter that it will rest within said envelope 21 at a considerable angle therewith. Mercur is provided within said envelope to a evel slightly below the opening in the straight end of said shield 28 when the envelope is in a level position, and is divided into a pool 30 inside of shield 28 in contact with inlead 22, and a pool 31+ outside said shield in contact with the inlead 25. The walls of said. shield 28 rise around seal 23 to a height somewhat above the lowermost part of the opening in the opposite end of said shield, so that the mercury pools 30 and 31 cannot mingle through that opening. When the envelope is tilted so as to tend to raise pool 30 above pool 31 the Vmercury passes through the open end of shield 28 and merges the two pools, thereby connecting inleads 22 and 25. When the envelope is restored to the level position illustrated the mercury flows in the reverse direction through said open end of shield 28 until the bottom thereof 1s at the same level as the mercury, when the mercur rated bythe end of said shie d 28 into the two pools 30 and-31, and an arc takes place between the two pools as the circuit is opened. As the pool 30 is receding rapidly at this time due to the sloping bottom of the shield 28 the are is drawn within said shieldr28 ,whereby said envelope 21 is shielded from the heat thereof.

Fig. 7 shows a modification of theswitch is again sepa.

of Fig. 6 which is designed to interrupt larger currents, and in addition to being somewhat larger has a slightly different support; ing means for the sh1eld, as made necessar by a change in-structurewhich even more e fectively shields said envelope from the arc.-

thereof is closed, and an opening 32 is `made in the bottom thereof near the end through which the mercury flows when the envelope is tipped. Inlead 25 engages with a projection 33 on the end of said shield 28 to rigidly hold that end of said shield against the top of envelope 21. Mercury is provided to a height just below the lowermost point of opening 82 when the envelope is level, forming the pools 3() and 31 as before. The operation is the same as that of the switch of Fig. 6, the break occurring between pools 30 and 31 over the lowermost point of opening 32, so that the are is almost entirely enclosed within said shield 28.

Greater sensitivity may be obtained in any of these switches by etching the portion of the barrier over which the mercury flows with hydrouoric acid previous to introduction within the envelope. The simplicity of this compared to etching the inside of the envelope as has been done heretofore is obvious.

It will be observed that by the structure illustrated in the various gures the inner` parts are fixed in position within the envelope without resort to packing.

When used on direct current the shielded inlead is connected to the negative side of the line so that the hottest part of the arc is well within the shield.

I claim:

l. In a mercury switch a tubular envelope,

Y a tubular lining within said envelope, leads sealed into said envelope, one of said leads forming an exterior support for said tubular lining, another of said leads terminating within said lining and mercury in said envelope in sufficient quantity to frm a conducting path between said leads when the switch is in a closed circuit position.

2. In a mercury switch a tubular envelope, a tubular lining within said envelope, .leads sealed into said envelope, one of said leads forming an exterior support for said tubular lining, another .of said leads terminating within said lining, and mercury in said envelope in sufficient quantity to form a conducting path between said leads when the switch is in a closed circuit position, said tubular lining being at such an angle with said envelope that the arc occurring upon opening of the circuit is drawn within said .tubular lining.

3. In a mercury switch a tubular envelope, a tubular lining within said envelope with one end closed and the other end upturned, leads sealed into said envelope, one of said leads extending into said upturned end of said tubular lining, and another of said leads forming an exterior support for said closed end of said tubular lining, an opening in the lower side of said tubular lining and Inercury within said envelope in a quantity sufficient to form a conducting path between said leads through said opening when the Signed at Hoboken in the count of I-Iudi son and State of New Jersey this l th day of September A. D. 1928.

WARREN R. WALKER.

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