US1608900A - Electric switch - Google Patents

Description

Nov. 30,1926. 1,608,900

F; H. MAYER ELEcTRm SWITCH Filed Jan. 5, 19 5 attouwq 5 break an electric circuit, generate,

Patented Nov. 30, 1926.

SETA 'FIES 1 tetanu FRED n. MAYER, or SALEM, OREGON.

ELEGTRIG SWITCH.

Application filed January. 3, 1925:, SerialNo. 337;

My invention relatesto electric switches or devices for the making andbreaking of an electric circuit through separable contact terminals, for ensealing such contact terminals in a dc oxygenized atmosphere, that is to say. in a vacuum or in a properly confined volume of gas that is substantially free of oxygen.

Contact terminals. which, in air, make and by the arc produced in the make-and; break operation, nitric acid from themoi'stureof the air and itsconstit-uent elements, to wit, hydrogen, nitrogen, and oxygen. Nitric acid is, as is well known, a powerful oxidizer of all metals except gold and platinum, its presence, considering the prohibitive cost of said metals, makes the commercial production of ordinary electric thermostatic switches, for example, practically impossible. This is due on the one hand to the prohibitive cost on the other to other metals.

By my invention it is made entirely practicable tonseordinary make and break cop per contacts in electric switches for indefinitely long periods of time without necessity for renewal of the contacts or for attention to them of any sort. This application is a continuation in partof my copending application, Serial No. 595,288, filed @ctoher 18, 1922', the character herein claimed embodied in. an electric iron, and arranged so that the heat radiated by the resistance elements may be conducted through or penetrate the casing of the switch, and thereby aiiect the thermostatic element.

lVhat constitute my invention will be hereinafter specified in detail and succinctly defined in the appended claims.

In the accompanying drawing:

the short life in service of Figure I is a longitudinal section partly.

elevation of one form of embodiment K invention.

n'nre II is a view similar to Eigure l', the same subject-matter, but taken a angles to the view in Figure I.

.-.gure III is a view corresponding, in t, to Figure II. but showing a modified form of embodiment of my invention.

Referring first to the numerals on Figures I and II of the drawing, 1 and 2 indicate, respectively, the two leads of an electric circuit which communi ate with each other and consists in providing means I siliency and of acid res1sting metals, and 1 which shows a switch of through a source of electric energy,.not illustrated, They are assembled by air tight joints with an insulating head 3, upon opposite sides of which they are respectively united to'conductive arms 4: and 5, which are provided, respectively, with contact terminals T and18, Said terminals normallymalre contactin consequence ofthe cooperative-reot the arms 4; and 5. i

One or both of the said arms is a thermostat whose action is controlled by a variable degreeof thetemperature to which they are exposed. At a predetermined critical degree-of temperature, therefore, one or both of the arms automatically bends so as to break the-contact which normally exists between theterminals 7 and 8, thereby breaking circuitthrough the leads 1 and 2.

My invention consists inproviding, in respect to suchacombination in any variation of form which may be imparted toit, means for-protecting the terminals 7 and 8 from the; effects upon them of oxidation, to which they are exposed when surrounded by air. To that end provide an air-tight case 9 of heat penetratable or conducting material, of any suitable character into. which the arms 4: and 5 are introduced, and to which the head 3 is hermeticallysealed.

The interior, of the case 9 is provided with a deoxygenized atmosphere which the case confines to the exclusion of -air. By the term deoxygenized I designate any gaseous atmosphere or a vacuum (so far as it is attainable) which is either substantially or entirely tree of oxygen. The atmosphere within the case 9 may be deoxygenized either by exhausting the oxygen of the air within it, or by entirely displacing the air with a gasthat is tree of oxygen. Any known or preferred; method "for removing, in effect, the oxygen maybe employed at will.

The terminals 7 and 8 may be made to operate within an atmosphere: such as has beenspecified so, as to make or break circuit through their agency, The absence fa-rs n. nsaid. atmospher y" p e n s; he f rmation: Qtit c ac d upo t e terminals, prolongs,- as; has; been already specified, the life of them indefinitely,and makes it practicable to make them of a cheap metal, such, for example, as copper.

In Figure III, I show a modification of the form of embodiment of my invention in which one of the elements shown in the preceding figures is eliminated, though in etfeet retained. In that figure, the leads 1 and 2 are connected, respectively, with the conductive head 10 of a thermostatic longitudinally curved or bent metal case 11, and with a cooperative, preferably curved arm 12 carried by the head 10 within said case. The case 11 is flexible and is thermostatic in so far as it tends to straighten under heat in consequence of the expansion of the gas confined within it. The heat necessary to effect that result may be developed from a source outside the case which, for this purpose, is of heat conducting or penetratable material as disclosed in my copending application above referred to, or in any other suitable manner. The arm 12 is joined to the lead 2 through the head 10 "from which said members are insulated as by the aid of an insulating stufiing box 14.

The free end of arm 12 within the case 11 is provided with a contact terminal 15, which makes normal contact, substantially as illustrated, with a contact terminal 16 on the inside concave bend of the case. Means of adjustment of the relationship of the arm 12 to the case 11 so as to elfect such degree of nicety of contact between the terminals 15 and 16 as may be desirable, is rep resented by a screw 18 threaded in a block 19 provided on the outside of the case 11, and through an insulating block 20 within said case, interposed between the case and the arm 12.

In the modified form of embodiment of my invention last referred to'as shown in Figure III, a sufficient tendency to straighten the bend of the case 11, induced by heatas above indicated, for example, will have the efiect of breaking contact between the terminals 15 and 16.

The case 11, like the case 9, and with like effect, confines within it a deoxygenized atmosphere.

Furthermore, by actuation of the screw 18, variation of pressure may be communicated through fiexure or". the case 11 to the arm 12 with the effect of adjusting the contact terminals, for example 15 and 16, towards each other. Such adjustment may be employed not only it the arm 12 or the case 11 is, in effect, a thermostat, but it also instances means for positively actuating the terminals to make and break contact between them in the absence of any provision for their automatic or thermostatic control.

The operation of my invention in any of its various forms of embodiment may be briefly described as follows.

Breaking of contact between any two contact terminals such, for example, as the terminals 7 and 8 or the terminals 15 and 16, is etlected through a thermostat by elevation, to any predetermined critical degree, of the temperature to which theinstrument is exposed. Such raising of the temperature would, of course, result from heat generated by the electric circuit made by con tact between the terminals included in it, and communicated, in any way as by induction or radiation, to thermostatically responsive element of the instrument, towit (in either of the two instances specilied), to one or both of the arms 4 and 5 or to the atmosphere within the curved case 11.

Through adequate movement of the responsive element, induced either by varia tion of temperature or by manual actuation, contact between the terminals will be either made or broken, as the case may be. At some point in the making and in the breaking of contact an electric arc will be formed between the terminals. It the terminals are at such time exposed to air, the arc will generate nitric acid upon terminals of base metal, with injurious effect upon them, as already specified; but by aid of my invention, through exclusion of oxygen from the terminals, the generation of nitric acid will be eliminated. Consequently the injurious effects upon the terminals will not follow, and the life of the terminals will be greatly and indefinitely prolonged.

lVhat I claim is:

1. An electric switch comprising the combination with separable electric contact terminals, of a flexible, longitudinally bentconductive case ensealing said terminals therein, one of said terminals being operatively fixed to said case, and the case being adapted to straighten by expansion under heat of the atmosphere confined within it.

2. An electric switch comprising the com bination with separable electric contact terniinals of a flexible longitudinally bent conductive case ensealing said terminals within a deoxygenized atmosphere, one of said ter- -minals being operatively fixed to said case and the other being flexibly mounted tor ad justment relative thereto, said case being adapted to straighten by expansion under heat of the atmosphere confined within it.

In testimony whereof, I have hereunto set my hand.

FRED H. MAYER.

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