US2596684A - Steam electric iron - Google Patents

Description

May 13, 1952 R. HEDENKAMP 2,596,684

' STEAM ELECTRIC IRON Filed Dec. 3, 1945 2 SHEETS-SHEET 1 i; HEI;

` 5kb/11,', I

ao 82 66 yg: 2

alf 6s g l as 62 ,2 E

/lf 5'/ 5l /o k l w INVENTOR May 13, 1952 R. l.. HEDENKAMP STEAM ELECTRICl IRON 2 SHEETS-SHEET 2 Filed DeC. 5, 1945 WKN Patented May 13, 1952 UNITED ENT 7Gil? FICE .2,596,684 i sTEMELEcT-RICYIRON Richard- L. HedenkampfKirkwood, M0.

:Application December s, 1945, s-eriarNogcszAss 11 This invention relates in;generalrtosamrons of the electrical resistance-heated'typefandhas particular reference-to improvements insadirons of this character, `including `improvecli-'facilities adapting the same forso=calld^steam-pressing An object of the invention^fis*torprovidaa greatly simplified and. fullyeftective' *steam-electric iron for. domesticuse" or use'inj' commercial pressing establishments 'and the likeff which"A is fully capable of employmenteitheras'zian-independent steam-'electric '.iron," as'ahot"iron"without the steaming provision,"or as a:"steam=electric iron in connection'with a. constant"s upply of water to permit continuous useof"thefiron'for any extended period' as may be desired.

Another object is to provide S an W'improved steam-electric iron ofanovel and relativelyfsimpliled construction,v in which are embodied `effective steam generating and steam `deliverypro vision and automaticmeans "inic'ontrolofsaid provisions,V the' vlatter inc11`1'ding'n1`eans` aorcling facultative regulation l'of 'steam-delivery in pressing.

A further object is to, provide vin ariin'iproved ironfof 'the character indicated; ast'eam generating provision which is effective for 'steamj generation onlyw when the iron islin al. pressing position, and excessive" pressure r'elieving l' provisions' including a thermostatically "controlled [pressure relief valve in operative associationwith". the steam generator.

OtherA objectsV andv advantages of the-'present improvements will appear readily from the'A following description of a presently preferredembodiment of the invention asmexemplifiedrby the accompanying drawings, wherein:

Figure 1 is a sectionalelevation ofl the-lm proved iron, as taken longitudinally therethrough;

Figure 2 is an enlargedsectional view-"ofthe steam valve assemblyllofthe'- steaml generating means;

Figure 3 is a fragmentary` plan view-off'the sole plate of the iron;

Figure 4 is a longitudinal vsection through-fthe 45 sole plate, as viewed from lined-4in Figure-- 3;

Figure 5 is a fragmentary plan view ofthe-sole backing plate;

Figure 6 is a longitudinalsection throughz.,.the backing plate, as viewed fromzlinefS--B-in Figure 5;

Figure 7 is a fragmentary'planviewof azgasket plate utilized with thefsole andfbackingvplates, and

lFigure 8 isa longitudinal section-throughwthe ..2 gasket/plate; as viewed lfrom .line-f 8-"8 in` Figlure?.

Referring to the -drawingand rst to Figure 1,fthe vpresently-'improved iron includes-a pressingor sole-'plate 510, a backing plate IIS-of ribbed construction (Fig. 5), superimposed onthesole plate; an electrical heating resistance unit I2' of plate-like form, interposedbetween the sole and -ba'cking plates, ancla gasket plate I4 between the l0-unit I2 and the inner surface of the sole-plate.

Thesepartsare secured in assembly by any suit- 1 able Ymeans, such-as the vstudv bolt I5, andby present preference, additionally by the Valve casing YI of the main steam control valve' pres- .il ently to be described. Overlying theV plate assemblyabovedescribed, is a casing or hood mem- ;ber; 4S which may besuitably removably vsecured to the platestructure in any well known man- "ner, or by`-means preferred andv presently tobe 20 "described, and vexternally on the hood in'av hol- )lowhandle' I9. 'An'ielectric cable 20 for supplying'the resistance unit I2 `with heating' current, is.A extended through a handle. opening 22V preferably at the rearfend'of" the handle, and thence 25` through the handlev tov .a` connection of one -lead l,23. tdtheheatinglunit I2, and the opposite vlead V2li to onejterminal 28 of a suitable thermostatic heat regulatoindevicel 2],Uthe construction and i. operation of which is we1lknown. The device 21 -j-30flocatedfin -the forwardend of the hood I8;-and f suitably Inounted'upon the-backing plate II,1has itsfopposite terminal 2,8connectedto the heating tunit-'IZwby alead-BU. Regulationof the thermoo fzsstatic .controlfdevice .to determine the degreeof "UDf-ironfheatingisf presently effected by a rotary finger-tip awheelfgelement 3 I secured; uponl the :thermostat: control-shaft 32 and exposed through the? forwardfside ofilthefhandlef I9. -By present xpr'eference,thewheel 3 I Lhas'an' ofPf position in lwhichsfthef conductor' circuitto 'the hea-ter unit I2 "is open-'circuitedithroughthe device 21.

' The hood I Y -which Visf-formed `from' a lsuitable r rust-resistantmetallic sheet material, i supports i i interiorly thereof a wall'memberlloflike rust- 'resistantA material, thewall preferablybeing suitab1y"secured 'alongf'its margins to'. the hood and lformingiwith the-latter, `a v'chamber' or water 2'reservoir'35. Aninternallythreaded port 36 nor- `r50.mallyclosed by ia' threaded plugV '38, is provided in "the top of! thelhood,^forfthe..admission ordischarge of water relative to the .reservoir ."35. Longitudinally spacedbaiile plates 43 9 having. ports l 40 therethrough Y. extend .transversely fof fthe 55.-. chamber andserve to dampen reciprocatory motion of the body of water in the reservoir dur communicating juncture 48 inwardly of the forward tip end 50 of the sole plate, and extending centrally -longitudinally of the plate from the juncture 48, is a supply channel5l. The channel 5I from its end somewhat centrally of the sole plate surface 42, is continued through opposite preferably curved branch supply channels 52, into communication with the side channels 43 Yas illustrated in Figure 3. Steam delivery to the pressing face or surface 54 of the sole plate is afforded from each of the side channels 43 through-a series of passages 55 through the plate, each passage terminating in an outwardly flaring or conical port 56 opening to the plate surface 54. From the passage 55 at the juncture 48, the passages in each channel 43 are increasingly relatively spaced along the channel as shown in Fig. 3, in order to provide efficient distribution of steam to the fabric under press beneath the sole plate. Moreover, the arrangement of the supply and delivery channels and passages in the sole plate is such as will least affect uniform heat distribution throughout the sole plate.

Steam generation in the channels 43, 5I and 52 is facilitated by the close adjacence thereof to the resistance heat unit I2 overlying the same. However, in order to prevent direct contact of steam and water vapor with the unit I2, a relatively thin plate gasket I4 (Figs. 7 and 8) heretofore referred to, formed of a non-corrosive metallic material, is interposed between the heating unit I2 and the sole plate and forms the top closure for the several channels. The gasket platefurther is characterized by'high heat conductivity, and Vhence serves to conduct heat to the channels for steam generation therein.

Water supply to the steam generator channels is effected from the reservoir 35 through the valve casing I6 (heretofore mentioned) of a control valve device 58 (Figs. 1 and 2). Valve casing I6 is externally threaded at 59 over its lower section,

- for threaded reception in a threaded opening 60 ceive both the valve casing and the flange 64 of the gasket opening 62. An assembly nut 66 on the threaded valve casing, serves to lock the valve casing to the sole plate by clamping engagement with the backing plate I I, and additionally aids the stud bolt I5 in holding the sole plate, backing plate, gasket and heater unit in clamped assembly. The upper portion of valve casing I6 is formed to provide an annular flange seat 61v and a central upstanding, neck 68, the latter projecting inwardly of the reservoir 35 (Fig. l) through an opening 10 in the reservoir wall 34. The wall marginal portion 1I vdefining the opening 18. is seated on the casing seat 61 and is 4 firmly clamped thereon by a nut 12 threaded onto the neck 68. It is to be noted here that the nut 12 in clamping the wall margin 1I to the casing seat 61, affords a ready means for removably mounting the hood IB and the reservoir to the pressing plate assembly.

The casing neck 68 is axially bored to provide a frusto-conical valve seat 14 therein, for cooperation with a control valve 15. Extending radially through the neck 68 and opening in the valve seat 14, are water delivery passages 16, these communicating through radial passages 18 in the nut 12, with the reservoir chamber 35. Opening to the valve seat 14 axially thereof, is a neck passage 19 which is outwardly enlarged or iiared at its lower end to provide a valve seat for a ball check valve 82 of a predetermined weight, arranged in the longitudinal chamber 83 of the valve casing. A pin or stop element 84 projected transverselyV of the chamber 83 below the ball 82,r retains the ball valve in -operative relation to its seat and limits opening displacement of the ball valve. Nearv the lower end of casing chamber 83 are diametrically opposite passages 86 through the casing I6, these passages being provided to communicate chamber 33 with the central channel 5I in the sole plate I0.

Control valve 'I5 is carried by or formed on the lower end of a valve stem 81 which extends upwardly through reservoir 35 and terminates in a threaded head 88 vthreadedly received through a nut 90 secured to the hood I8 as shown in Fig. l. The upper exposed end of the head 88 has suitably attached thereto, a control handle or finger-tip control knob 9|V through which the valve stem 81 may be rotated for adjustably relating the valve 15 to its seat 14. Since the nut 90 is fixed, rotation of the threaded head 88 therein serves to displace vthe valve stem and valve upwardly or downwardly according to the direction of head rotation, so as to determine correspondingly, a lesser or greater restriction by the valve 15 to iiow communication between the valve seat passages 'I6 and 19.

Near the upper end of the forward wall portion 92 of the chamber 35 and above the normal level of water in the reservoir when the latter is filled, is a vent port 94 which is controlled by a valve element 95 externally of the chamber on the end of a thermostatic member 96 fixed at its lower end to the wall portion 92 (Fig. 1). The purpose and function of this valve controlled vent 94 will appear presently.

In normal operation with a suitable .volume of water in the reservoir 35 and the iron electrically heated to the desired temperature as controlled by the device 21 regulated through the wheel 3l, adjustment of the valve 15 to an open position as effected through the fingertip control 9I,permits a correspondingly regulated iiow of water from the reservoir 35 through valve passages 18, 16 and 19, past the ball check valve 82 and into the valve casing chamber 83. The interior of chamber 83 is heatedv from the heater unit I2 by heat conduction through` the gasket plate flange 64 in close surface contact with the valve casing I6, and thence through the valve casing I6, so that the water admitted'to the chamber 83 becomes heated and tends quickly tor vaporize therein. The water vapor'V thus formed then passes through chamber passages 86 into and along the sole plate channels 5I and 52 to the side channels 43. In these channelsD the water vapor is transformed by high heat conduction from the heater unit I2 Ythrough the gasket plate .la-intesteamr and -asthefsteamas .so generated, it issues* throught 3the -s'ole 'plate ports" .56 tothe pressingsurface:- ofthe Jiron jfor steaming and moistening the'fabrieunder press.

" -Normally the.; ball check valve* '8 2' will remain open; but in theteve'nt' of=an'undesirableior-"inordinate risel in steam or'vapor1` pressure `in. the casingfchamber 83;' the-'ball valve Will-respond by upward displacement toclose 'the-passageL 19 for preventing ysteam -or vapor flow into Y'the reservoir 35. NWhen' such pressure-isrelieved'through'the sole plate ports 56, the ball check willreturn vto lits openv position for continued. steaming'foperation of the iron.

' While 4the wvater supplyv'alve "l 15 normally regulatesl the rate `fof water *delivery-from the reservoir :1:0- the steamgenerator; it also vserves as a safety'release device-in"the-eventl the valve and there'is avolumefofrvvater'fin'the-reservoir.

-If under these conditionsf-the-iron ish-employed for any appreciable period; the 'indirect heating 'of the vreservoir water; as'throughiheatconduc- Vtion thereto through` the valvecasing- I6 andiwall 3ft-will produce eventually a considerable vapor pressure in the reservoir, tending-'if'prolonged, vto'reach a dangerously-high valueif not relieved.

Accordingly, the present'improvements affording the support of the valve 15Y`directly'onthe yhood 18 (Fig. l), thusenables relief of excessive vapor pressure in the reservoir, since the vapor pressure passages.

-will afford suicientpressure fordeliveryofwater through the controlvalve to the steam'generator However/in the event of; inordinate heating of the water flow vvalve' Ain* the region of the valve seat -1 Il, such Vas to lproduce vaporization of the water in such zone, Whichif permitted to continue would prevent-'water lldelivery *to the steam generatorpassages, vthe resulting vtemperature of the water-in the reservoir 'andconsequent heating of the wall portion 92 `to-vvhich the thermostat 96 -is` securedywill-cause`fthe thermostat to move valve195;into'vaposition-of vent closure at the vent -port#94. Consequently, the vapor pressure will-'rise'1inf-thereservoirl-35 to a 'point which will"assure'positive'bpressure flow ofwater and vapor past'the 'ow controlr valve to the steam generator passages. f Moreover, should `the pressurelbuild-iup" in `thereservoir proceed more rapidlyth'an it cani be `rel-ieved'l through the open ow control valve,"the"ver`1t valve 95'wi11 respond to pressure approaching vdangerous limits, by opening -thevent SlltoI allovrescape of vapor beneath thefvhodl I8 and eventually to be appreciated ythat by` reason:tl-iereof,` waterl atmosphere, thus-relieving the'pressure in the reservoir.

v-By locating the "loW' controlvalve 1d-"I5 near the forward end'ofthe reservoir 35;-and`by forming the -reservoir such* @that fits* length --is many -times the maximum depth;v thereof .f aslbyA a ratio of the order of 3 or 4 to 1 forexample,fit"will delivery-to the steamfgeneratormay occurfonly when the iron is in a substantiallyfhorizontalior pressingw position. 'Tilting theiron" rearwardly 'so that it restsupontheA rearl ends of --the hood -l 8 and soleplate l0, or upon' the'rear ends of the "hood I8 and-handle 19, will bring'the-waterfllevel *in the -reservoir)-bel0w the seat lll-of the control Thus-by tilting the iron between-pressing operations,y 'the period' of pressing service with 'f each -fllling of' the reservoir.' may* lee-materially increased.

'1 When it isldesiredto operate the iron merely as a' --hotiron,- without 'the steaming' provision,

the `reservoir-'may -be lemptied'-oflwaterthrough the filling' -opening 36. -Moreover, 'the-l present i assembly-iis such as'to facilitate complete Edrain- -age of vthe reservoir, valve passages and steaming Ypassages in fthesole plate `IIL-"when the ironis to be stored for any extended'perid'this being accomplished byremoving the hood lthrouglr removal v of theassembly'V nut 12. Then the reservoir VWater may' be `dischargedithrough either or both the opening 10 and the'lling opening .36,

ywhile the valvepassages and steampassages may vbe equallyreadily emptied` of all. moisture. The

nut'12 can be vremoved by rst rotating the valve stem 81 out 'ofengagementwith nut 90,-- then rotating nutemlfout of engagement with` hood I8, and finally inserting a tool through the-opening normally occupied by nut 90 andturning nut 12.

A further feature of the presentrimprovements Y.concerns the ready adaptation of the iron for continuous steaming :operation in .instances where pressingis to be conducted'orlong periods at a time, as f occurs in commercial pressing establishments for' example. The threaded filling opening- 36` isselected such thateit is suitable to receive one end ofl a' flexible; pipe or -hose '(not shown) leading from a constant source of water, as'the house water systermso as .to provide a constant supply. of` water in the reservoir 35. The same result may be obtained in domestic use where it isdesired, through alike hose connection as to awater tapor-'thelike 'From the foregoing, it lvvill4 now appear that there is aiforded by the present improvements,l an electric-steam Airon having al1 ofthe advantages hereinbefore--enumerated and' others now apparentfandwhich is of greatly-simplified and economical construction and fullyautomatic in its operation. While buta single preferred embodiment ofthe iron isvv herein-shown` andA described, nevertheless, it is to be `understood that alterations and modifications of the parts and their arrangement, may bemade Without departing `from the spirit and full intended scope of the inventionf as defined by the appended claims.

What I claim is:

l. In a sadiron, a pressing plate, saidpressing plate having openings therein for-outlet of iluid, a heatingA element in heat-transferring relation with said pressing platef afluid reservoir spaced from said pressing plate, a valve seat at the bottom of said fluid reservoir, a passage from said valve seat to the openings in saidpressing plate, and a valve stern that is adjustably supported by the top of said uid 'reservoir andv is in register with said valve seat, said valve stem rbeing supporated by a portion ofsaid reservo-ir and being movable relative to said Vportion of said reservoir to move'toward and away from'said valveseat, said'fluidv reservoir being deformable by excessive V'pressure to move saidrp'ortion' thereof AandJ-said valvestem away fromrsaidrvalveseat 'tovent-said pressing plate.

2. In a sadiron, a pressing plate, said pressing plate having openings therein for outlet of fluid, a heating element in heat-transferring relation to said pressing plate, a fluid reservoir spaced above said pressing plate, a valve that controls flow of fluid from said fluid reservoir to said openings in said pressing plate, a vent in a wall of said fluid reservoir and a thermally responsive element that is normally spaced from said Vent but is a-ctuable by heat to close said-vent, said vent normally being open to permit gravityinduced flow of fluid from said fluid reservoir t said openings in said pressing plate, said vent being closable by said thermally responsive element to permit the generation of a pressure in said fluid reservoir that will induce flow of fluid from said fluid reservoir to said openings in said pressing plate, said thermally responsive element being of resilient material, said thermally responsive element being deformable in response to excessive pressure in said fluid reservoir to open said vent even when said element is heated.

3. A sadiron that comprises a pressing plate, said pressing plate having openings therein for outlet of steam, a fluid reservoir, an outlet for said fluid reservoir, a'passage between said outlet for said fluid reservoir and said openings in said pressing plate to conduct fluid from said uid reservoir to said openings, a manually-operated valve that regulates the flow of fluid through said passage from said fluid reservoir to said openings in said pressing plate, a pressure-responsive valve element that is positioned between the outlet of said fluid reservoir and said openings in said pressing plate, and a valveseat that is intermediate said outlet of said fluid reservoir and said openings in said pressing plate, said valve element being movable by the pressure of steam adjacent said openings toward said valve seat to prevent flow of steam from said pressing plate into said fluid reservoir. l

4. A sadiron `that comprises a pressing plate,

said pressing plate having openings therein for outlet of steam, a fluid reservoir, an outlet for said fluid reservoir, a passage between said outlet for said fluid reservoir and said openings in said pressing plate to conduct fluid from said fluid reservoir to said openings, a manually-operated valve that regulates the flow of fluid from said uid reservoir to said openings in said pressing plate, a pressure-responsive valve element that is positioned between the outlet of said fluid reservoir and said openings in said pressing plate, and a valve seat that is intermediate said outlet of said fluid reservoir and said openings in said pressing plate, said valve element being movable by the pressure of steam adjacent said openings toward said valve seat to prevent flow of steam from said pressing plate into said fluid reservoir, said pressure-responsive valve being positioned between said manually operated valve and said openings in said pressing plate and being normally open.

5. A sadiron comprising a pressing plate, said pressing plate having openings therein for outlet of steam, a fluid reservoir, an outlet for said fluid reservoir, a passage between said outlet for said fluid reservoir and said openings in said pressing plate to conduct fluid from said fluid reservoir to said openings, a manually-operated valve that regulates flow of fluid through said passage from said fluid reservoir to the openings in said pressing plate, and a pressure responsive valve element and seat between said manually-operated valve and said openings in said pressing plate, said pressure-responsive valve normally in open position to permit flow of fluid from said fluid reservoir to said openings in the pressing plate but being closable against said seat in response to the pressure of the steam in said openings in said pressing plate to prevent flow of fluid from said fluid reservoir to said openings on said pressing plate and toprevent flow of steam from said openings in said pressing plate into said fluid reservoir.

6. A sadiron that comprises a pressing plate. said pressing plate having openings therein for outlet of steam, a heating element in heat-transferring relation with said pressing plate, a fluid reservoir, an.outlet from said fluid reservoir, a passage between said outlet for said fluid reservoir and said openings in said pressing plate to conduct fluid from said fluid reservoir to said openings, and a pressure-responsive valve that is positioned between the outlet of said fluid reservoir and the openings in said pressing plate and is openable to permit passage of fluid to the pressing plate and is closable to isolate said fluid from the fluid reservoir so it can generate considerable pressure, said valve being normally open but being closable by the pressure of steam in said openings in said pressing plate.

7. A sadiron that comprises a pressing plate, said pressing plate having openings therein for outlet of fluid, a heating element in heat-transferring relation to said pressing plate, a fluid reservoir, a vent in a Wall of said reservoir, a resilient closure for said vent, a valve seat at the bottom of said fluid reservoir, and a valve stem that is adjustably supported by another Wall of said fluid reservoir and is in register with said valve seat, and said valve stem being adjustable relative to said other Wall of said reservoir to move toward or away from said valve seat and thereby stopor pass liquid to said openings in said pressing plate, said resilient closure being deformable to permit opening of said vent when the pressure in said fluid reservoir becomes excessive, said reservoir being deformable to move said other wall of said reservoir and the valve stem supported thereby away from said valve seat when the pressure in said fluid reservoir becomes excessive.

8. A sadiron that comprises a pressing plate, said pressing plate having openings therein for outlet of fluid, a heating element in heat-transferring relation to said pressing plate, a fluid reservoir, a vent in-a wall of said reservoir, a

resilient closure for said vent, a valve seat at the move toward or away from said valve seat and thereby stop or pass liquid to said openings in said pressing plate, said resilient closure being deformable to permit opening of said vent when the pressure in said fluid reservoir becomes excessive, said reservoir being deformable -to move saidother wall of said reservoir and the valve stem supported thereby away from said valve seat when the pressure in said fluid reservoir becomes excessive, saidA resilient closure being thermally responsive to the temperature of said fluid reservoir to opensaid vent when the fluid in said fluid reservoiris cool. ,j v v-9,. Ina sadiron of; the character described, a

pressing plate assembly including an electric heater element, said assembly providing steaming passages therein opening to the pressing surface of the assembly, a hood arranged over` said assembly and formed to provide a deformable uid reservoir therein, a member :arranged between said assembly and reservoir and formed to provide passage means communicating the reservoir with said steaming passages, a valveseat past which fluid flowing through said passage means must flow, and a valve element, said valve element being movable against said valve seat to prevent iiow of iiuid through said passage means and being movable away from said valve seat to permit flow of uid through said passage means, said valve element being supported by a wall of said fluid reservoir and being adjustable relative to said wall to move against and away from said valve seat, said wall of said uid reservoir being movable upon deformation of said iiuid reservoir to carry said valve element away from said valve seat, said uid reservoir deforming upon the generation of excessive pressures therein, thereby moving said valve element away from said valve seat and permitting :duid to ow through said passage means and vent said pressure.

10. In a sadiron of the character described, a pressing plate assembly including an electric heater element, said assembly providing steaming passages therein opening to the pressing surface of the assembly, a hood arranged over said assembly and formed to provide a deformable fluid reservoir therein, a member arranged between said assembly and reservoir and formed to provide passage means communicating the reservoir with said steaming passages, said member being secured :to one wall of said reservoir, a valve seat on said member that communicates with said passage means, and a valve element that is movable toward and away from said valve seat to prevent or permit flow of uid through said passage means, said valve element being supported by that wall of said fluid reservoir which is opposite to said one wall and being movable relative to said second Wall to move toward and away from said valve seat, said second wall being adapted to move said valve element away from said valve seat Iwhenever pressures Within said fluid reservoir deform said fluid reservoir, said fluid reservoir being stiff and normally being capable of maintaining any predetermined setting of said valve element relative to said valve seat.

11. In a sadiron of the character described, a pressing plate assembly including a heater element, said assembly providing steam passages therein opening to the pressing surface of the assembly, a uid reservoir arranged over said assembly, a valve seat and a valve element that are separable to permit flow of fluid from said fluid reservoir to said steam passages and are engagable to prevent flow of uid from said fluid reservoir to said steam passages, a vent in one wall of said uid reservo-ir to vent pressures created within said iiuid reservoir, and a thermally-responsive element positioned adjacent said vent, said thermally-responsive element normally being spaced from said vent to permit ready venting of pressures within said fluid reservoir but responding to heat to move toward and close said vent, said thermally-responsive element being of resilient material, said thermally responsive element responding to excessive pressures within said fluid reservoir to move away from and open said vent but being again movable toward said vent whenever said pressures have been vented.

RICHARD L. HEDENKAMP.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,548,957 ,Slobotkin Aug. 11, 1925 1,681,911 Spencer Aug. 21, 1928 2,178,512 Schreyer Oct. 31, 1939 2,188,011 Miller Jan. 23, 1940 2,309,427 Wolcott Jan. 26, 1943 2,313,382 Kistner Mar. 9, 1943 2,316,907 Wallace Apr. 20, 1943 2,322,593 Riddington et al. June 22, 1943 2,337,078 Morto-n Dec. 21, 1943 FOREIGN PATENTS Number Country Date 330,870 Great Britain June 19, 1930

Images