US2459057A

US2459057A - Vapor electric device with cooling coil serving as heating resistor

Info

Publication number: US2459057A
Application number: US6716A
Authority: US
Inventors: Winograd Harold
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1948-02-06
Filing date: 1948-02-06
Publication date: 1949-01-11
Anticipated expiration: 1966-01-11

Description

Jan. 1l, 1949. H. wlNoGRAD VAPOR ELECTRIC DEVICE WITH COOLING COIL SERVING AS yHEATING RESISTOR 2 Sheets-Sheet l Filed Feb. 6., 1948 :l s s s s E u xm.

SERVING AS HT WING RESISTOR 2 Sheets-Sheet 2 Filed Feb. 6, 1948 l eef 35 the vacuimi vessel of Patented Jan. 11k, 1949 UNITED STATESA PATENT? ,oFFlcE VAPOR ELECTRIC DEVICE WITH COOLING COIL SERVING AS HEATING RESISTOR Harold Winograd, Milwaukee, `Wis.,assignorvto Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application February 6, 1948, Serial. No. 6,716

. 1 VThis invention relates generally to the manufacture of electric valves and relates particularly to improvements in means for expelling occluded gases therefrom.

' An object of the invention is the provision for the expulsion of occluded gases from the elements of an electric valve, a process known as degassing or forming, at temperatures at which the atmospheric pressure normally exerted on the valve may exceed the elastic limit ofthe valve casing.

Another object of the invention is to expel occluded gases from substantially all surfaces of l `the casing of an electric valve at temperatures `at which the atmospheric pressure normally exerted on the valve casing may exceed the elastic limit thereof.

Another object of the invention is to expel occluded gases from an electric valve by providing for the application of heat internally of the valveg.,

casing, utilizing for this purpose an integral element of the valve in a capacity other than its primary function.

Another object of the invention is to expel occluded gases from an electric valve by providing for the application of heat internally of the valve casing without introducing auxiliary 'for preventing oxidation of exposed elements of an electric valve during the degassing thereof at elevated temperatures. f The novel features of this invention and ho the objects are obtained will appear from lthis specification and the accompanying drawings showing several embodiments of the invention and forming part of this specification and allthe novel features are intended to be pointed out in the claims.

Fig. 1 is a vertical section of an electric valve and vacuum vessel illustrating apparatus embodying the invention.

. i Fig. 2 is an enlarged vertical section ofthe fluid tight seal between the electric valve and the apparatus shown in Fig. 1;

claims. (c1. 25o-27.5.)l

v v Fig. 3 isa bottom view of the helical pipe baffle Showninria1.. y f

Fig., iis an` enlarged vertical section of one offthev fluid cooledelectrical terminal connectors and insulated riser of the pipe baie shown in Fig. 1.

Fig. 5 vshows another embodiment, partly in section andpartlygin elevation, of the apparatus shown in Fig. 1. c

Referring to Fig. 1, the apparatus here shown comprises a vacuum tank or vessel I I, into which an electric valve generally designated I2 has been placed for ,degassing or forming. By the 4terms degassing or forming is meant the expulsion of occluded gases from the elements of vthe,electric `4valve at elevated temperatures. By

vacuum formedtherein.'

The Avacuum vessel II is substantially cupshaped, comprising a vertically disposed cylindrical wall I3 partially closed at an upper end thereof bya top disk I4 having an axially disposed circular aperture. The cylindrical wall I3 has the,l lower 1 end thereof closed by a `bottom disk I6. Both thetop disk I 4 and bottom disk I5 are adjoined to the wall I3 in fluid-tight relation thereto in any suitable manner, as by welding. Since the vessel I I isrequired to withstand an koverall applied external pressure not exceeding atmospheric pressureatnormal operating temperatures,the walls I 3 of the cylinder, the top disk I4 and the bottom disk I6 must be constructed ofmater'ial of appropriate strength, such as steel, and of theproper thickness.

The electric valve I2 shown at least partly inserted within the vacuum vessel II is a vapor electric device of the single anode type, and comprises va substantially vcylindrical vcup-shaped casing Il which is preferably made of conducting material, such as steel, but which may be made of an insulating material,- such as glass. The casing I'I must have a wallthickness sufficient to withstand atmospheric pressure at service temperatures. The casing Il. is closed by a diskshaped anode plate or cover I8, the casingvI'I being dished outward at the rim to form a flange I9 following the peripheral contour of the cover I8. The cover I8 is preferably made of a material such as steel and is sealed in fluid tight relation to the ycasing Il by any suitable'means,

as by welding flange I9 to the cover I8 at the periphery thereof.

As will be apparent inFig, 1, the cover` I8 of ltop of the casing I1.

casacca'- preferably made of a conductive material, such as stainless steelwhich is not attacked by water or by mercury, and serves to cool thevalve I2 .during service operation thereof.

4f- The pipe baffle 52 is preferably of circular cross section forming a passage for the iiow of water or other cooling fluid. The balile 52 is preferably assembled as a unit comprising two helixes v"of pipe joined at one end, as shown in Fig. 3,`by 4`an interconnecting tube 53, and having the turns of the respective helixes interleaved in spaced relation.y By constructing the pipe baiille 52 in this 1fashion, a noninductive winding is created. How- Yever, the pipe baille 52 maybe wound from a 'Isingle helix to form an inductive winding if so desired. The turns of the pipe baille 52 are insulated one from the other by a plurality of circumferentially spaced spool-shaped insulators 50 which preserve the rigidity of the pipe baille 52k and prevent the sagging of individual turns thereof upon the application of heat thereto.

"The free ends of the helixes of the pipe baille 52 terminate in upward extending risers 54 for leading the pipe baille through the cover I8. Risers `54 penetrate the cover I8 diametrically and are respectively sealed thereagainst by means of a flexible composite vitreous and metal seal assembly 55, as shown in Fig. 4. In addition to sealing the risers 54 in iiuid tight relation against theV cover I8, the seal assemblies 55 electrically insulate the pipe baille 52 from the cover I8 and `casing I1. To protect the seal assemblies 55 against breakage, each seal assembly f55 is surrounded by an upward extending sleeve 56 mounted in any suitable manner on the cover I8. An

annular insulator 51 closes the sleeve 56 and electrically insulates the riser 54 therefrom. An annular gland 58 cooperates with the insulator `51 `to seal the insulator 51 against the riser 54.

Referring to Fig. lit will be observed that at the lower end of the pipe baille 52, the interconnecting tube-53 joining the helixes provides a support for the disk-shaped baille 5I. In turn, the baille 5I supports a graphite ignition-excitationanode 59 insulated therefrom. A suitable potential maybe impressed on the anode through an insulated lead-in connection 6 I. Below the cathode 44 a device 62 of any suitable type, such as of the electro-magnetic type, electrically and mechanically momentarily connects the cathode pool 44 with the ignition anode 59 when it is desired to ignite an arc at the cathode during normal operation. A funnel-shaped shield or gutter 63 supports the pipe baile 52,\.the gutter 63 being suspended by means of a plurality of axially depending rods 64, only one of which is here shown, from an inverted pan shaped shield 85 located near the The shield 85, which ex-` tends over and around the upper portion of the grid 48, and is penetrated by the risers 54 in in# Asulated relation thereto, is itself suspended from the cover I8 and insulated from the grid 48 and `cover I8 by means of the segmental insulators 49. The electric valve I2, subsequent to assembly and prior to normal service operation, mustbe Aconditioned for the passage of current between the anode 38 and cathode 44, the conditioning process comprising degassing or forming, as well as evacuating. In other words, it is necessary to expel occluded gases from the elements of the valve I2, as well as expel free gases from the interior of the casing I1 before the valve I2 can normally function. The term gases includes :actual gases, as well asmoisture, greasep'and "gases from 'the elements of the valve I2 is to heat the relements at an .elevated temperature in a vacuum; 'Although the pipe baille 52 has the primary. function of providing a means for circulating' cooling'iluid for the removal of heat radiated `bythe arc and' elements of the valve I2 when the 'valve I2 is normally'operated inservice, the pipe baffle 52 lmay be utilized in a secondary capacity to heatthe elementsoi the valve during degassing. This-may be done effectively by employing the pipe baille 52 as a resistance heater. Accordingly, means for supplying a heating current to the pipe baiile 52, the means being here shown schematically vas an alternating current generlator 6B and' associated power transformer 81 having a tapped secondary winding, is connected to the risers 54 kthrough terminal connectors 68. Although a low or intermediate frequency generator and transformer is here shown, the means for supplying a heating current to the pipe baffle 52 may otherwise comprise either a high frequency generator and transformer or a direct current generator.

Referringto Fig. 4, the terminal connector 68 here shown comprises a straight cylindrical tube, having anz axially extending bore therein. The connector is made of conductive material and has a flared extension 1I closing the bore at one end. The connector58 together with a contact ring 12 having a plurality of segments is coaxially inserted into the passage of the riser 54. The ring 'I2 engages a threaded portion 13 of the connector 68 lying directly above the flared extension 1I and extends coaxially below the threaded portion 13 to embrace a. substantial portion of the extension 1 I. It will be apparent that the segments of the ring 12 are shaped at their outer peripheryto follow the contourof the inner wall of the riser 54,- and at their inner periphery to follow the contour of the `connector 58. By turning the connector 68 in a predetermined direction about the linearaxis thereof, the segments of the ring 12 are forced to move radially outward against the wall `of the riser 54. The resulting wedging action of the ring 12 against the inner wall of the riser 54 establishes'a positive electrical connection between the connector 68 and the pipe baille 52. By wedging the connector 68 against the ,riser 54 at a point a material distance below the lcomposite seal assembly 55, the seal assembly 55 is afforded relative protection from the heat generated inthe pipe baille 52 upon the passage of ycurrent therethrough. The segments of ring 12 arespaced from each other to define a passage for the-removal of air and other gases from' the interior of the pipe baille 52.

vn uid; A'second tube 16 penetrates the cap 14 at right angle to the first tube 15 to connect with an annular space in thebore surrounding the first tube 15. The tubes 15, 16 are sealed to the cap 14by any suitable means, as by welding the tubes 15, 16 tothe cap 14, and provide respectively an :entrance and an exit for circulation of cooling fluid.' Ihe fluid'enters the connector 69 preferin'ably'through the axially disposed lfirst tubeg15,

2 flows through .the annular; space surrounding the tube k'15, and .leavesthrough thesec'ondtube 16. Directly beloivthefcap 14' is a lug Vl4 to which the transformer .67 is connected. .Below the lug 'l1 and embracing the connector 68 isa collar 18 `with the vcollar 4'I8 and .the connector .68 Yandthe collari'lii and the riserll, andretained in place by means oi` respective glands 82, 83 bolted tothe collar i8. The collar i8 of 'one of the connectors 68 has a radially extending boreintercepting the axial boreimmediately above the end of the riser 54. A tube 84, `only a portion of which ls shown in Fig. 4, is inserted into a portion of the radial bore of the collar 73 and retained therein by means of an annular gasket. 85 and associated cooperating gland 86. As shown in Fig. l, the tube 8 leads to evacuating means, here shown as a rotary vacuum pump 81 driven by a suitable electric motor 88. By means of the pump 81 a vacuum can be established in thei-nterior of the pipe baille 52 to prevent oxidation thereof during the employment of the pipe baffle-52 as a resistance heatentheggases being withdrawn through the annular space surrounding the connector 68 and through the passage defined by the segments of ringy T2. The gases flow through the tube 84. The other connector 68 isslmllar except/that there is no opening in the collar 18 for connection to an evacuating means. i i

Evacuating means is also provided forl evacuating the casing of the electric valve and may compriseas here showrraI molecularpump 89 using a suitable vaporizable material,- and a rotary vacuum pump .Si jdriven bya suitable electric motor S2. y .l t t Having described and illustrated apparatus suitable for degassing an electric valve, it is now meet that the assembly and operation thereof he described, particularly with reference to the type of valve here shown.

Let us assume for the purposes of illustration,

that the valve i2 shown in Fig. 1 has just been assembled and suspended in the vacuum vessel il for degassing. Digressing for the moment, it should be noted that a portion of the electromagnetic device 62; namely, a coil, not shown, has been disconnected and removed from the valve casing il so as not to expose that portion of the device 62 to the heat applied during degassing. The clamping ring is fastened downto securely seal the cover I8 ofthe valve l2 tothe vesseljl l, thereby making the vessel''ll fluid tight. The valve i2 is now ready for connection to the power transformer 6l. The conn'ectingnterminals Scare inserted into the risers Eiland respectively wedged therein as hereinbefore described.A The collar18, which Ais already inA engagement with the exposed upward portion of the connector 68 is madevfast lto both the riser ft and the connector 68- by `adjusting the glands 82, 83 to insures. uidwti'ght seal betweenthe' riser 5t and the collar 18 and between the collar i8 and the connector 58.

Finally, with the connection of the power transformer 61 to the lugs Tl ofthe connectors 68, the electrical heating circuit isi/complete. The ilow of currentxupon subsequent energization of the circuit kis from Athe transformer B1 through the pipe .baffle 52..v and back .tothetransformer 6 1.. Since: the seal-i assemblies `55,-may beyinjured' ,by

the :application 'of .high temperatures-necessary for degssin'g .the valve, cooling means, such as a cooling fluid from a suitable source, not shown, is circulated through the connectors 68 at all such timesthat' a current is circulated through the pipe baille 52. vBy providing cooling means for the connectors 68, the heat generated by the pipebaiile52 and connectors 68 during the operationofthe pipe barde 52 as a resistance heater isprevented from reaching and damaging the seal assemblies 55.

A rxal step in the assembly is to connect the vacuum pumps? to the pipe baille 52 through the tube 84 and one of terminals 68, and to connest the'remaining vacuum pumps 89, 9| to the casing of.' the'valve 12,. Y I v'Having' completed the assembly of the apparatus, the degassing process or operation may beginne' Y The vacuum pumps 33, 39, 9i, 81 are started and after the desired vacuum is reached in each of the components of the apparatus; namely, .the casing I 'L'pipe bafile'Z and vacuumvessel Il, current is gradually or abruptly applied to the pipe baiile 52. The degree of vacuum in each component may be measured by any suitable known measuring. means such as a hot wire or McLeod gage, not shown, the vacuum measuring means being'here omitted because it forms no part of the invention.

.The temperature generatedin lthe pipe baille 52 maybe controlled by changing the taps of the power transformer 67 to vary the voltage'and givetlie desired value of heating current. The transformer El serves as-a current source to supply current to the coils vof the pipe -baie 52 and causes the coils to reach a temperature at which 4occluded gases are given up, not only by the pipe baie 52 but also by the other elements contained in the casing of the valve l2. The evacuatlng ymeans vfor the casing, here shown as pumps 89, 9|, cooperate with the current source 6'! in removing the occludedv gases from the valve elements, which include the pipe baille 52 and the casing I'I.

It has been found that the apparatus performs most effectively to expel occluded gasesfrom the elements .of the-valve at a mean pipe bailie temperature range of irom .800 to 900 C. At this temperature range the elements of the valve are found to give up a large portion of the gases occluded therein. I After the required degree of degassing has been obtained, the electrical heating circuit is opened andthe valvev l2 allowed to cool off gradually while the pumps 89, 9| continue to operate. At a predetermined intermediate valve temperature the `cathode vaporizable material is introduced into the casing il by any suitable means, not showin When the temperature of thevalve I2 has reached a sufficientlyvv low predetermined .value the evacuation connection to the pumps 88', .'91 is sealed-on". The valve i2 isnow hermetlcally sealed and the connection to the vacuum pumps 85, Si may be removed. If thereafter, the valve iswoperated; in service at a temperature substantiallylower than the degassing temperature, the original vacuum can be maintainedwithout 'having to further evacuate the casing of theivalve at periodic intervals. x

The degassing at high temperatures of elements of the valvel which in service operate :at relatively low temperatures, eg.; the casing il and-the Apipe baiilez52, leads to aimo'st important resultvvhen the valve is placed in service. For

thenthese sameelements, the Vcasing I 1 and pipe baille 52 being here representative of such elements, will act as' highly effective absorbers of gases given oi by the other elements of the valve which in service operate at high temperatures, e. g., the anode 38, grid 43, baffle I and excitation anode 59. Therefore, by degassing the valve as hereinbefore described at elevated temperatures, a good vacuum can be maintained over an extended period in the valve after the sealing thereof, even though some gases are given 01T by these elements, namely, grid, anode, etc. which operate at high temperatures during service operation.

When the pipe baiile 52 and elements of the electric valve I2 are heated to a temperature of from 800 to 900 C., the casing I1 of the Valve I2 reaches a dull red heat. It is well known that regardless of the type of steel which may be used in the casing I2, the yield point and tensile strength thereof are greatly reduced at such temperatures as compared with the yield point and tensile strength of the same steel at 20 C. Reference is made to the U. S. Bureau of Standards, circular C447, Mechanical Properties of Metal Alloys, wherein values of yield point and tensile strength for steels of various compositions are given as a function of the temperature. For example, a steel containing 0.15 carbon has a yield point of 42,000 lbs. per square inch at 27 C. (80 F.) as compared with only 3,800 lbs. per square inch at 760.'C. 1400 F.). It follows that a casing, as here shown, made of steel having a, 0.15 carbon content, if constructed with a wall thickness having a reasonable factor of safety under atmospheric pressure at 20 C., would collapse under the same pressure at 800 C. For this reason the valve I2 is contained, as here shown, in the evacuated vessel II, before being subjected to high temperatures. If no vacuum vessel surrounded the valve during degassing thereof, it would be necessary to thicken the casing walls substantially beyond their present thickness to withstand the atmospheric pressure at elevated temperatures. From a commercial and engineering point of view, such a thickening of the casing walls would be costly and impractical. Therefore, the vacuum vessel I I is utilized to protect the casing of the valve I2 from destructive external pressures during degassing.

The walls I3 of the vacuum vessel I I mustvalso be protected, during the forming of the valve, from heat radiated by the casing I1, since the heat radiated may raise the temperature of the Walls I3 of the Vessel II with a subsequent reduction in the yield point thereof below a safe value. Such protection from heat radiated by the valve I2 is adequately aiorded through the nest of

heat bailles

25, 26, 21 and insulation 3| hereinbefore described, the

bafes

25,26, 21 returning a large proportion of the radiated heat to the casing I1 of the valve I2. In this way not only is the vacuum vessel I I protected but the heat loss is reduced. Since a lesser amount of heat isv required, the current in the pipe baiil 52 may be reduced to a smaller value.

'Although the elements of the valve I2 may be safely raised to a temperature of 800 to 900 C. to expel the occluded gases therefrom, the composite metal and vitreous seals 42, 55 in the cover I8 of the valve lz'would be damaged at such temperatures. Accordingly, the valve I2 is in* serted in the vacuum vessel I I in such a manner, as here shown in Fig. 1to leavethe cover I 8 and the seals 42, 55 exposed to the cooling inuence ofthe ambient air.

If more positive cooling protection is desired, or, if it is desired to protect the exterior of the cover I 8 and the metal of the seals 42,755 from the undesirable effects of oxidation at elevated temperatures, vor both, the valve I2 may be further enclosed by means of an auxiliary cupshaped vacuum tank 93, as shown in Fig. 5, which is kplaced in an inverted position over the cover I8 of the valve and sealed thereto in fluid tight relation by means of a suitable annular gasket 94 interposed between the rim of the tank 93 and the cover I9. A radially extending flange 95 forming part of the tank 93 and having a plu,- rality of circumferentially spaced holes to receive the studs 23 of the vacuum vessel II cooperates lwith nuts 24 to retain the tank 93 in position atop the cover I8. The tank 93 is penetrated by the connectors 68 and the conduit leading to the vacuum pumps, not shown. Appropriate annular gaskets 96 are provided at all such points of pene tration 'of the tank, the gaskets 95 being retained in fluid tight relation thereto by means of annular glands 91 cooperating therewith and secured to the tank 93 in any suitable manner, as by bolts, not shown.

A reservoir 98 containing nitrogen or other suitable inert gas under `pressure is connected through a stopcock 99 to the tank 93 at one side thereof, and a suitable evacuating means, here shown as a rotary vacuum pump |00 driven by an electric motor I 0I, is connected through a conduit to the other side of the tank 93. -The riser 54 communicates directly with the interior of` the tank 93.

As constructed and arranged the tank 93 .oiers means for protecting the seals 42, 55 and other exposed elements from oxidation, the protection being aiforded by either of one of two methods. In the rst method the tank 93 is evacuated, the petcock 99 being in the shut-off position. Since the pipe baille 52 opens into the tank 93, the pipe baille 52 is likewise evacuated by the pump I00. Any gasesy which might contribute to oxidation of the exposed elements as well as to oxidation of the interior of the pipe baflie 52 are thus removed. In the second method the gases in the tank 93 and pipe baiile 52 are withdrawn therefrom by means of the-pump |00 and inert gas which is contained in the reservoir 98 is introduced therein. In the second method the stopcock 99 is in the open position. The introduction of an inert gas in contact with the pipe baiile 52 and other exposed elements of the valve I2, which elements are at an elevated temperature, prevents the oxidation thereof during the degassing of the valve I2. If cooling of the seals 42, 55 mounted on the cover I8 ofthe valve I2 is desired, over and above the cooling already provided by the cooling fluid flowing in the connectors 68, the inert gas may be introduced continually into the tank 93 and exhausted through the petcock I02 during the forming of the valve I2. Thus a constant stream of cool inert gasy is vcirculated in proximity to the seals 42, 55, conductor 39 and radiator 43. i The tank 93 and the Vessel, II thus comprise first and ysecond vacuum vessels into which one and another portion of the valve I2 is inserted, the vessels II, 93'being sealed to the valve l2 and evacuated as hereinbefore described.

Although but two embodiments of the present invention have been herein illustrated and described, it will be apparent to one skilled in the art that various changes or modications, singly or collectively, may be made therein without del1 parting' from the s' int of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1-. In combination, an electric valve comprising ari evacuated casing and conductive elements disposed Within said casing, conducting means for cooling saidy valve disposed vvithin said casing adjacent to said elements, and means' including a source of current connected to said conducting means for the heating thereof to heat said elements of said electric valve to expel occluded 'gases therefrom.

2. Iny combination, an electric valve comprising an evacuated casing' and conductive elements disposed Within said casing, conducting means forming a passage for the ilow of fluid for cooling said valve disposed within said casing adjacent to said elements, and means including a source' of currentconnected to s aid conducting means for the heating thereof to heat said elements of said electric valve toy expel occluded gases therefrom.

3. In combination, an electric valve comprising an evacuated casing', conducting means forming a passage for the flow of fluid for cooling said valve disposed Within said casing, and means including a source of current connected to said conducting means for the heating thereof to expel occluded gases from said conducting means,

4.- Iil combination, an electric valve comprising an 'evac'ua'te'd casing, conducting means having a Wall portion deining a passageway for the now of iluid therethrough for cooling said valve, said conducting means being disposed within said casing, and means including a source of current connected to said conducting means for the heating thereof to expel oc'clnded gases from said passage- Way.

5. In combination, an electric valve comprising a sealed casing and conductive elements disposed Within said casing, evacuating means connected to said casing for fluid evacuation thereof, con'- dlicting means forming a passage for the iiow of uid for cooling said valve disposed Within' said casing adjacent to said elements, and a source of heating current connected to said conn ducting means for heating said conducting means to heat said elements of said valve, said current source cooperating with said evacuating means to remove occluded gases from said elements.A

6. 'n combination, a vessel, an electric valve comprising a sealed casing and elements disposed Within said casing, at least a portion of said casing being inserted in said vessel, means for sealing said vessel against said casing to prevent the ingress of Huidv to said vessel, evacuating means connected With said vessel and said casing for huid evacuation thereof, a conductor disposed Within said casing, and a source of current connected to said conductor for supplying heatf ing current thereto to heat said elements of Said lect-ric valve, said current Source cooperating vv-ith said evacuating -nans Yto remove occluded gases from said elements, said conductor, and` said casing.

ni combination, a vessel comprising a wall portion, insulatir'igineans including heat reflecting 'means disposed Within said vessel in spaced relation with said Wall portion, an electric valve comprising' a s'ealed`cas`iiig, and elements dis'- posed Within said casing, at least a portion of said easing' being inserted in said vessel, ineens foia sealing said vessel against the'ing'ress of fluid, evcl'latiig means corihectedfw'ith said vessel and said casing for fluid eva'oda-tion4 thereof, a oon-'- ductoi disposed Within said casing, a source of current connected to said conductor for supplying heating current thereto to heat said elements of said valve, said reflecting means shielding said vessel against heat radiated from said casing, and said current source cooperating With said evacuatiiig hieahsto Vle'irlov'e occluded gases from said elements and said casing.

8. In combination, an electric valve comprising a casing and elements disposed within said casing, conducting means having a wall delining a passage for the flow of fluid for cooling said casing and said elements, said conducting means disposed Within said casing adjacent to said elements', means for leading said conducting means through said casing including means for establishig a' fluid tight 'seal therebetween, a source of heating current, means for connecting said conducting means to said current source to heat said conducting means 'to heat said elements and said casing' to expel occluded gases therefrom, said connecting means including a connector coafx'ially introduced into said passage of said conducting means and connected to said wall thereof within said casing at a material distance from said salig e'ls to pv'eht 'the transmission of deleterious heat from said conducting means to said sealing means, said connector comprising a portion having a passageway for the flow of cooling huid therethrough, and another portion engaging said wall of said conducting means to dehe` a passage, and evacuatn'g means connected 'with said passage and said casing, said evacuating means cooperating with said source to remove oc- 'eluded gases from said Wall of said conducting' means and from said casing and said elements of said valve.

9. In combination, an electric valve comprising an evacuated casing and elements disposed within said casing, conducting means having a Wall defining a passage for the flow of fluid for cooling said valve, said conducting means disposed within said casing adjacent to said elements, means for leading said conducting means through said casingyiiiclldiflg h'leans for establishing a fluid tight seal therebetween, a source of heating current, means for connecting said conducting means to said current source for heating said conducting means to heat said elements of said valve to expel occluded gases therefrom, said connecting means ihcllding a connector 'coaxi'ally introduced into said passage of said conducting means and connected to said Wall thereof within said casing at a material distance from said sealing means to prevent the transmission of deleterious heat from said conducting means to said Vsealing means.

l0; Ih combination, an electric valve compris ingan 'evacuated casing and elements disposed With-in said casing, conducting means having a Wall defining apassa'ge for the iloW of iluid for cooling said valve, 'said conducting means dis posed within said casing adjacent to said elements, means fol" leading said conducting means through said casing including means for establishing a lid tight seal therebetween, a source of heating current, means lfor connecting said conducting means to said current source for heating sai'd conducting -means to heat said elements of said valve to expel 'occl'uded gases therefrom, said connecting means including a connector coaii'iall-'y introduced into said passage of said conducting means and connected to said wall thereof Within said envelope 'at a material distance from said scali-ng means to'pre'vent the transmission of deleterious heat from said conducting means' to said sealing means, said connector comprising relatively movable members so constructed and arranged as to wedge one of said members against said wall of said conducting means upon a predetermined relative movement of another of said members to effect a positive electrical connection between said current source'and said conducting means.

11. In combination, an electric valve comprising an evacuated casing and` elements disposed Within said casing, conducting means having a wall defining a passage for the' flow of iluid for cooling said valve, said conducting means disposed within said casing adjacent to said elements, means for leading said conducting means through said casing including means for establishing a uid tight seal therebetween, a source of heating current, means for connecting said conducting means to said current source for heating said conducting means to heat said elements of said valve to expel occluded `gases therefrom, said connecting means including a connector coaxially introduced into said passage of said conducting means and connected to said Wall thereof within said envelope at a material distance from said sealing'means to prevent the transmission of'deleterious heat from said conducting means to said sealing means, said connector having a passageway for the flow of cooling uid therethrough, and evacuating means connected with said conducting means and cooperating with said current source to remove occluded gases from said wall of said conducting means.

12. In combination, an electric valve comprising an evacuated casing and elements disposed within said casing, conducting means having a wall defining a passage for the flow of uid for cooling said valve, said conducting means disposed Within said casing adjacent to said elements, means for leading said conducting means through said casing including means for establishing a fluid tight seal therebetween, a source of heating current, means for connecting said conducting means to said current source for heating said conducting means to heat said elements of said valve to expel occluded gases therefrom, said connecting means including a connector coaxially introduced into said passage of said conducting means and connected to said wall thereof Within said envelope at a material distance from said sealing means to prevent the transmission of deleterious heat from said conducting means to said sealing means, said connector comprising a portion having a passageway for the flow of cooling uid therethrough, and another portion engaging said Wall of said conducting means to define a passage, and evacuating means connected to said passage and cooperating with said current source to remove occluded gases from said wall of said conducting means.

13. In combination, a vessel comprising a wall portion, an electric valve comprising a sealed casing and elements disposed within said casing, at least a portion of said casing being inserted in said vessel, heat reecting means disposed Within said vessel intermediate said wall portion and said casing, means for sealing said vessel against the ingress of fluid, evacuating means connected with said vessel and said casing for fluid evacuation thereof, a conductor disposed within said casing, a source of current connected to said conductor for supplying heating current thereto to heat said elements of said valve, said reflecting means shielding said vessel against heat radiated from said casing, and said current source cooperating r14 with said evacuating means to remove occluded gases from said elements, said conductor, and said casing. a

14. In. combination, a vessel comprising a Wall portion, anelectric valve comprising a sealed casing and-elementsdisposed within said casing, at

least a portion of said casing being inserted within said Vvessel,insulating means disposed in vsaid vessel adjacent said wall portion, reflecting means disposedvwithinsaid vessel intermediate said wall portion and said' casing, means `for sealingsaid vessel against the ingress of iiuid, evacuating means connected to said vessell and said casing for duid evacuation thereof, a conductor disposed within said casing, a source of current connected to said conductor for supplying heating current thereto to heat said lelements and said casing, said reflectingf'means cooperating with said insulating means to shield said'wallportion of said vesseljfrom heat radiated'frcm said casing, and said currentH source' cooperating with said evacuating meansto remove occluded gases from said elements and said casingr-l 15. In combination, ya vessel comprising a wall portion, an electric valve comprising a sealed casing and elements disposed within said casing, at least a portionof said casing being inserted in said vessel, `insulating means disposed Within said vessel intermediate said wall portion and said casing, means for sealing said vessel against the ingress of fluid, evacuating means connected with said vessel and said `casing for fluid evacuation thereof, a conductor disposed within said casing, a source of current connected to said conductor for supplying heating current thereto to heat said elements of said valve, said insulating means shielding said wall portion of said vessel against heat radiated from said casing, and said current source cooperating with said evacuating means to remove occluded gases from said elements, said conductor, and said casing.

16. In combination, a vessel comprising a wall portion, insulating means-including heat reflecting means disposed within said vessel in spaced relation with said wall portion, an electric valve comprising a casing and elements disposed within said casing, at least a portion of said casing being inserted in said vessel, means for sealing said vessel against the ingress of fluid, evacuating means connected with said vessel and said-icasing for uid evacuation thereof, a conductor disposed within said casing, anda source of current connected to said conductor for supplying heating current thereto to heat elements of said valve, said reflecting means shielding vsaid vessel against heat radiated from said casing and said current source cooperating with said evacuating means to remove occluded gases from said elements, said conductor, and said casing.

17. In combination, a vessel, an electric valve comprising a sealed casing, and elements disposed vvithin said casing, at least a portion of said casing being inserted in said vessel, means for sealing said vessel against the ingress of fluid, evacuating means connected with said vessel and said casing fornuid evacuation thereof, a conductor disposed within said casing, and a source of current connected to said conductor for supplying heating current thereto to heat elements of said electric valve, said current source cooperating with said evacuating means to remove occluded gases from said elements, said conductor, and said casing.

18. In combination, an electric valve comprising an evacuated casing and conductive elements -15 f disposed within said casing; conducting means forming a passage for Vthe flow of fluid :for cooling said valve disposed within said casing adja cent to said elements, means for leading said conducting means through said easing including sealing means cooperating with saidcondueting means and said easing, a source of heating ourn rent, and fluid .cooled means connecting .said c urrent source with said conducting means for supplying heating `current thereto to heat said elements .oi said valve to expel oecluded gases therefrom, said fluid cooled means connecting -said source to said conducting `:means within said casing at a point materially distant from said seal-ing means to prevent the transmission of 20. In combination, a rst vessel, a second vessel, an electric valve comprising a sealed :oasingand elements disposed Within said easing, at least a portion of said valve being insert-ed in said nrs-t vessel, andat least another portion of sa-idvalve being inserted in said second vessel, means for sealing said vessels to said easing to prevent the ingress of fluid to said vessels, evacuating means connected With each of said vessels and said cas-ing for fluid evacuation thereof, a conductor disposedwithin said easing, and a source of current connected to said conductor for supplying heating current thereto to heat said elements of said electric valve, said cur-rent source cooperating with said evacuating means to remove occluded gases from said elements, said conductor, and said casing.

HAROLD WINOGRAD.

Y it-iiirlsaliisioEs CITED The following references are of record in the le of this patent:

o UNITED STATES PATENTs Number Name Date 2,170,695 Pike Aug. 22, 1939 2,428,000 v rWinograd 'Sept. 23, 1947