US2259111A - Double bimetallic gaseous relay - Google Patents

Description

A. H. LAIDIG Oct. 14, 941.

DOUBLE BIMETALLIC GASEOUS RELAY Filed Aug. 14, 1940 y l gaaaunuannnvb INVENTOR M f/p/a.

mLswrrwL TTORNEY Patented Oct. 14, 1941 2,259,111 DOUBLE BIMETALLIC GASEOUS RELAY Alfred B. Laidig, Bloomeld, N. J., assignor to Westinghouse Electric &

Pittsburgh,

pany, East Pennsylvania Manufacturing Com- Pa., a corporation of Application August 14, 1940, Serial No. 352,500

(Cl. Z50-27.5)

Claims.

My invention relates to gaseous discharge devices and especially to gaseous discharge thermal relays.

An object of my invention `is to provide a gaseous discharge thermal relay in which the ambient temperature does not affect the normal spacing between the electrodes.

Another object of the invention is to prevent distortion of the electrodes during heat treatment and exhaust of the device.

Another object of the invention is to provide a gaseous discharge thermal relay that may be utilized near places of high temperature or in large size refrigerators.

Other objects and advantages of the invention will be apparent from the following description and drawing in which:

Fig. 1 is a view in perspective, with parts broken away, of a preferred embodiment of the invention.

Fig. 2 is an elevational view of the device in Fig. 1 during heat treatment.

' provide bimetallic means Fig. 3 is an elevational view of the device in I Fig. 1 during operation.

Figs. 4, 5, 6, and 7 are elevational views illustrating various modifications of the electrode structure of Fig. 1.

Fig. 7 is a cross-sectional view on line VII-VII of Fis. 6.

'I'he purpose of my invention is to provide a gaseous discharge thermal relay that will not be deformed during heat treatment and exhaust common with such devices.

An additional object is to prevent the eil'ect of ambient temperatures on the spacing between the electrodes of such a relay. form, my invention is an improvement on the gaseous discharge thermal relay, such as disclosed in Patent 2,200,443 to E. C. Dench, issued May v14, 1940. Such gaseous discharge thermal relays include electrodes inside of a casing, such as the glass tube I0 disclosed in Fig. l. This tube contains a gaseous atmosphere, such as neon. argon, or a similar ionizable medium or combination of gases.

In order to make certain that the gaseous medium is pure, the various metal parts of the device'are heat treated, preferably by ahigh frequency induction coil II disclosed in Fig. 2. This coil is energized during the time that atmosphere and occluded gases in the metal parts are being exhausted through the tubulation I2. Since the device in the Dench patent is to gradually close the contacts under the heat of discharge, such contacts will close under the eIIect In its specific of the heat treatment, and frequently the effect of this heat treatment is to distort the electrodes both in shape and desired spacing from one another.

After the device has been formed for operation in the usual room temperature, an installaage warehouses. The eil'ect of such an installation with its low ambient temperature is to considerably slow up the action of the discharge relay. Furthermore, the device may be installed in a climate where the ambient temperature is always warm, with the result that the action of the relay may be accelerated toc much by the ambient temperature.

It is specifically an object of my invention to that will automatically compensate for the elIect of the ambient temperature on the bimetal or bimetals affected by the discharge. This .bimetallic means is connected to one or both of the electrodes and is designed to prevent ambient temperature closing the contacts. With such means, the closing of the contacts will be the sole result of a discharge between the two electrodes.

In Fig. l, I have disclosed a preferred embodiment in which a press I3 supports two electrodes. One of these electrodes such as I4 is preferably composed of a bimetallic strip having the metal layer of lower expansion on the side facing the other electrode I5. This other electrode I5 may I I. These electrodes are preferably coated with zinc to provide a low work function, and at a suitable distance from the upper ends each electrode preferably has a contact area I6 to take the wear from the shock of contact. Normally these bimetallic electrodes would be supported on standards I1 passing through the press I3.

In its preferred embodiment, I insert a bimetallic element I8 between the standards I1 and a connection I9 to the bimetallic element I l. As disclosed in Fig. 1, I prefer to install a second bimetallic element 20 between the standards I'I and the connection I9 to the bimetallic electrode I5. The bimetallic elements I8 and 20 are arranged so that the metallic layers of lower expansion are on the outside and the metals of higher expansion face one another. The surface of these bimetallic elements, or at least the surfaces facing one another, may be coated with a material of very high work function such as aluminum oxide. The elect of heat on the two pairs of bimetals, namely, I4 and I5, and I8 and 28, is the reverse. In other words, the top ends of tht` bimetals I4 and I5 will tend to contact one another, but the top portions of IB and 20.

vbut at the same time the top portions of the bimetals I8 and 20 will spread further apart with the result that contact and consequent distortion of the electrodes will not result from the high heat treatment necessary to remove the gases. After desired vacuum is obtained inside the casing I0, the induction coil II is removed and the desired gaseous atmosphere inserted within the tube and the tubulation sealed oi.

'I'he device is now ready for installation in an arrangement such as illustrated in Fig. 1 of Dench Patent No. 2,200,443. This iig-ure illustrates one of the most common applications of my invention which is for the purpose of starting a fluorescent lamp.

When the electrodes of my relay are connected to the lamp electrodes and a suitable source of power, a discharge will be initiated from one bimetal i4 to the other I5. This discharge will heat up the two bimetals I4 and I5 taking part in the discharge. The bimetals IS and 20 will not be aiected to any extent.

The result will be that the contact points I6 will close as illustrated in Fig. 3 because of the heat of discharge applied tothe two binzetals. As

y the contacts I6 close, the discharge between the two electrodes will be short-circuited by the contact, and the discharge in-my relay will stop. 'Ihe bimetals I4 and I5 will then cool and separate. As these two bimetals separate the discharge will be initiated in the gaseous atmosphere ofthe lamp.

If desired, shields 30 may be placed around the connecting portions I9 between the two b1- metals to prevent the possibility of the discharge between the two sets of bimetals such as from electrode I to the lower bimetal I8.

In Fig. 5, I have illustrated an embodiment in which the electrodes have only one bimetal of each set. The standard 3| has an electrode extension consisting of a small diameter wire 32 with a contact area 33 thereon, and the other electrode comprises a standard 34 'connected to a broad strip bimetal 35 similar to the bimetal I8 in Fig. 1 which is connected in turn by a connection 36 to a bimetal 31 sir'nilar to the bimetal I4 of Fig. 1 and having upon its upper end a con-l tact area 38. The action of the bimetal 35 in this modiiication is to counteract the eect of ambient temperature on the bimetal 3l', as previously explained. The construction of the broad on the inner side of the U. The other standard 42 has an extension 43 entering the mouth of the U so that the application of heat to the bimetal will Amove its contact end 44 to make contazt with the extension .43, as illustrated in dotted lines.

Intermediate the standard 42 and the contact portion 43 of this electrode, I preferably insert a U-shaped bimetal 45 with the metal of lower expansion on the outer side of the bimetal. The action of the bimetal 45 will be the reverse of the bimetal 44, namely, heat will move the extension 43 away from the bimetal 44 as shown in dotted lines, whereas heat will move the bimetal 4I closer to the extension 43.

Accordingly, under the heat treatment of the induction coil illustrated in Fig. 2, the contact portion of 43 will move away from the path of movement of the end of the bimetal 4I and there will be no distortion. However, when the discharge. is started, the bimetal 45 will not be affected thereby to any appreciable extent, and contact will be made between the two electrodes bythe movement of the bimetal 4I.

In Fig. 8, I have disclosed a still further modification oi electrode structure in which the standard 50 has a contact-making portion .5I adjacent the contact end 52 of an inverted and crimped bimetal 53. This bimetal 53 has two lateral indentations 54 near the at bottom por-- tion of the U in order that a tab of magnesium 55 may be inserted at the base of the U and bent down at either s ide of the U to be held loosely therein. This tab oi magnesium provides the lowered work function desired in starting the discharge.

The inverted U-shaped bimetal has a connection 56 to a U-shaped bimetal 5l having the position of its metallic layers reversed from that oi the bimetal 53. The bimetal 53 has its metal of lower expansion on the inner side and the bimetal 57 has its metal of lower expansion on the outer side. A shield 58 preferably of insulating material, intercepts any direct discharge lines between the two bimetals so that the discharge will beconflned to the bimetal 53 and the extension 5I of the other electrode. 'Ihe shield 58 in this figure as well as the shield 30 in Fig. 4 acts also as a heat shield between the discharge and the lower bimetal or bimetals.

Under the iniiuence of heat treatment as illustrated in Fig. 2, the bimetal 51 will bend the bimetal 53 to the position disclosed in dotted lines 53. In this position, contact will not be between the bimetal and the other electrode at 5I, and

hence there will be no distortion of the electrode structure.

It is apparent that I have disclosed an arrangement whereby the eiect of ambient temperature will be automatically compensated for in the gaseous discharge thermal relays illustrated. It

trode whereby the heat of discharge will bend said electrode into contact with the other electrode to short-circuit said electrodes and extinguish said discharge, and a second bimetal connected to one of said electrodes at a place removed from the-shortest discharge path between said electrodes, said second bimetal 'having its metal of lower expansion faced in the opposite direction to that of the lower expansion metal of said first .bimetal whereby said second bimetal will tend to compensate for the effect of ambient temperature on the first bimetal.

2. A gaseous discharge device comprising a container provided with an ionizable medium therein, two closely spaced electrodes therein, said electrodes having contact areas, one of said electrodes having a bimetal adjacent said contact area with the metal of lower expansion facing the contact area of the other electrode whereby the heat of discharge will make said contact areas join and short-circuit said electrodes, and a second bimetal connected to one of said electrodes at a place remote from said rst bimetal and having its metal of lower expansion faced in an opposite direction from that of the lower expansion metal of saidiirst bimetal whereby the effect of a change in ambient temperature on one bimetal to vary the electrode spacing is compensated by the effect on the other bimetal.

3. A gaseous discharge device comprising a container provided with an ionizable medium therein, a curved bimetal having its metal of lower expansion on the inner side, an electrode within the curved bimetal cooperating to form a discharge path therewith, a second bimetal connected to said bimetal ata place removed from said discharge path and adapted to move said electrode out of the'curved bimetal upon the application of high ambient temperature.

4: A gaseous discharge device comprising a container provided with an ionizable medium therein, two electrodes forming a discharge path, one of said electrodes having a bimetal as a terminal for the discharge path with its metal of lower expansion facing the other electrode whereby the heat of discharge will move the electrode into contact with the other electrode, said other electrode having a bimetal connected to it remote from the discharge path between the electrodes,

metallic element in said container adapted to be heated by. the ensuing discharge and operable to short-circuit said electrodes and extinguish said discharge, bimetallic means compensating forthe effect of ambient temperature upon said bimetallic element, and a shield interposed between said bimetallic element and said last mentioned b1- metallic means.

7. A gaseous discharge device comprising a container provided with an ionizable medium therein, two closely spaced electrodes therein, one of said electrodes includinga bimetal with its metal of .lower expansion facing the other electrode whereby the heat of discharge will bend said electrode into contact with the other electrode to shortcircuit said electrodes and extinguish said discharge, and a second bimetal connected to one of said electrodes at a place removed from the shortest discharge path between said electrodes, said second bimetal having its metal of lower expansion faced in the opposite direction to that of the lower expansion metal of said rst bimetal whereby said second bimetal will tend to compensate for the effect of ambient temperature on the first bimetal, and a shield interposed between said rst and second bimetals.

8. A gaseous discharge device comprising a containerprovided with an ionizable medium therein, two closely spaced electrodes therein. said electrodes having contact areas, one of said electrodes having a bimetal adjacent said contact area with the metal of lower expansion facing the contact area of the other electrode whereby the heat of discharge will make said contact areas join and short-circuit said electrodes, and a second bimetal connected to one of said electrodes at a place remote from said irst bimetal and having its metal of-lower expansion faced in an opposite direction from that of the lower expansion metal of said first bimetal whereby the e'ect of a changeV in ambient temperature on one bimetal to vary said last mentioned bimetalcompensating for the effects of variations in ambient temperature von said first mentioned bimetal.

5. A gaseous discharge device comprising a container provided with an ionizable medium therein, electrodes disposed within said container and between which a glow discharge occurs upon the application of a potential thereto, one .of said electrodes being adapted to emit electrons, a bimetallic element in said, container adapted to be heated by the ensuing discharge -and operable to short-circuit said electrodes and extinguish said discharge, means compensating for the effect of ambient temperature upon said bimetallic element, and a shield interposed between said last mentioned means and said bimetallic element.

` 6. A gaseous discharge device comprising a container provided with an ionizable medium therein, electrodes disposed within said container and between which a glow discharge occurs upon the application of a potential thereto, one of said electrodes being adapted to emit electrons. a bithe electrode spacing is compensated by the effect on the other bimetal, and a shield interposed between said first and second bimetals.

.9. A gaseous discharge device comprising a container provided with an ionizable medium therein, a. curved bimetal, having its metal of lower expansion on the inner side, an electrode within the curved bimetal cooperating to form a discharge path therewith, a second bimetal connected to said bimetal at a place removed from said discharge path and adapted tolmove said electrode out of the curvedbimetal upon the application of high ambient temperature, and a shield 55, interposed between said first and second bimetals.

10. A gaseous discharge device comprising a container provided with an ionizable medium therein, two electrodes forming a` discharge path,

one of said electrodes having abimetal as a terminal for the discharge path with its metal of lower expansion facing the other electrode whereby the heat of discharge will move the electrode into contact with the other electrode, said other electrode having a bimetal connected toit remote from the discharge path between the electrodes, said last mentioned bimetal compensating for 'the eiiects of variations in ambient temperature on said iirst mentioned bimetal, and a shield interposed between said bimetals.

NFRED H. LAIDIG.

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