US2601652A - Air-conditioned open top display cabinet - Google Patents

Description

Patented June 24,1952

. AIR-CONDITIONEDOPENTOPQDISPLAY CABINET David Franklin Williams "and JameslDonald T Williams,

Greenville, S.

20., i-assignors to williamsl Retrizei-ation lncq Greenville, 8.10., .a corporation of South Carolina The present invention 2 provides an improved air conditioned "display case or stand for dis- "playing 'and preserving perishable articles of food,

suchas fresh fruits andgreen'yegetables, where- 'inthe case' has iisdisplay or supporting face -directly open to the outside air 'and'is *free of enclosing "side walls or "front walls or top walls; and

WhereinYmeans are provided for maintaining the commodities being displayed on the table :in a

cool and htdnidifiedcoridition.

'Thedisplay stands'oi the general type to which this invention relates are-provided customarily with a cooling coil" around which the air" to be rem'ployed" for conditioning and preserving==the commodities is" circulated by forced circulation through the'provisionoi' a fan or blower which forces air from'th'e outside around the refrigerating coil over the commodities being "displayed. -Suc'h arrangements as are-employed customarily have certainob'iections. Among such objections, :theremay bei mentioned specifically highoperating" costsi'due to' the power consumption required for the 'operation of the refrigerating coils and *blowing means, lowered humidif ying 'efilciencies through desiccation of the air by extraction of moisture by the refrigerating coils; and .bywarm- 1 ing: eifectson the. circulatingair due toatmosp'lreric' "air being asperatedinto the circulating air due 'toz'the velocity of the forced circulation.

Thepresent invention has for one of its objects theprovision of an air-conditioning andhumidiiying display case for perishable food commodities l which eliminates the above-mentionemand other obj ectionsfi'inherent in -the customary constructions, by eliminatinga system of forced circulation and'provldinga system of circulation which maintains the moisture" content ofthe circulating air continuously substantially constant, "and which. causes the circnlationoi aii in the cabinet and over' the commoditie without admixture;

therewith of any substantial amounts of outside atmospheric air;

A further -obj'ect-of the invention is totprovide animproved "construction of the above-indicated character wherein the commodities displayed are cooled below a spoilagetemperature and are'kept A stillfurtherobject of the' invention is to' pro- 1 wide an improved-means for efiecting' condensation ormoisture contained in the air "circulating within; the. .case andzinrandi around: the display wcommodities; without the :iormation or ice; and idol: efiectln: utilization 'oi the condensed moisture 65. net; A is formed interior-1y. with a topwcooling for maintaining an effective hydrationiof the i commodities.

A still further object of thecinvention is to :provide an air-conditionedequipment of the. ,in-

i dicated character wherein circulation of air :is effected throughthe utilization of diiferent' specific gravities between relatively cooler and warmer 'air.

.A stilliurtherc obiectoiythis invention ispto 10 provides. display cabinet of. the above-indicated type ln iwhi'ch there is provided means for directwing: therein descending relatively. heavy cool air "currents laden with condensed moisture .iromthe cooling coil the; cooling compartment, in i and around thecommoditieg being. displayed and preserved, to the warm air compartment and aback to the coollngscompartment.and witha minimum of temperature change.

. .A still iurther object off-the inventionis toiprovide: an open displayycase of the above-indicated :character or typeqwherein the cool air circulating from theycoolingcoilover the commodities being displayed passes into the interior. of. the

wease by specific-gravity alone: and without the pheric air.

l A i still further object :of the invention is 1 to pro- ,vide an open displaycase havingauxiliary display. meansradaptedwto enhance the displays and .appearance. of the commodities.

A still further obj ectuof the invention is toprowide a display case of the described type wherein maximum storage space is provided through. the

elimination of forcedcirculationinstrumentalities comprising :unitsorrother mechanical parts.

Further objects of the invention will become apparent as the w description .proceeds, and the 1 .featuresxot :novelty will be pointed out .in. par- .ticularity in the appended claims.

The invention will he understood more readily :by reference toJthe1accompanying drawings, which rillustrate. one form of. the invention embodying the-improvements of the invention. In the drawings:

1 .isa transverse vertical sectional elevaation of thedevicerthe direction of-air circulathe improvedconstruction of thiszinvention comaprisesxa cabinet A, the .sides of which :are; provided with suitable heatsinsulation B. The-cabisection I and a bottom warm air and storage compartment or section 2. The top cooling section contains an oversized cooling coil 3 which occupies the major portion of the space of the compartment, mounted intermediate the coil 3 and rear wall 4 of the cabinet and spaced from both is a substantially vertically disposed partition insulated wall 5 which extends longitudinally from end to end of the cabinet A but terminates short of the top 'I to form avspace 6 and for enclosing the coil 3. The wall 5 defines a return air passage 8 between itself and the back wall 4 of the cabinet A, for directing the warm air from the warm air compartment through space 8 to coil 3, as will be pointed out further hereinafter.

The vertically disposed wall or splash plate 5 projects somewhat below the restricted throat 5' of the cooling section or compartment I and joins with the angularly disposed baflie plate section 9 which forms a continuation thereof and pro- J'ects forwardly and downwardly therefrom. This 'baffle plate extends longitudinally through the cabinet A, and is secured to the end wall portions III. The bafile plate 9 is provided with a plurality of longitudinally extending rifiies I I and terminates short of the bottom front portion I2 of the cabinet A. Mounted above the rifiles II and slightly spaced therefrom is a reticulated open commodity holding and display screen I3, which is secured to the end walls and the front wall I2 of the cabinet A and extends upwardly and rearwardly to a point adjacent to the juncture of the members 5 and 9. The front of the display screen I3 abuts the front wall I2 in which is mounted the double wall transparent glass panes I4 which permits ready viewing of the fruits and vegetables displayed on the screen I3, which latter with said pane structure. forms a display section I4. Said section may be divided section has a vertically depending top portion I5 and an inwardly inclined portion I6, which supports a reflecting mirror I'I that extends the length of the display cabinet A, the angularity of .the mirror I! being such as to reflect visibly to an observer facing the front of the cabinet the articles displayed on the screen I3. The end walls III are shaped somewhat symmetrically to the front vertical top wall portion I5 and the inwardly inclined wall portion I5 but project outwardly therefrom sufliciently to accommodate a mounting I8 for incandescent or fluorescent lights I9 which are disposed to illuminate the mirror I! and the articles on the screen [3. As illustrating a suitable construction, the mirror Il may be inclined at an angle from about 67 deg. to '75 deg. to the top'inclin'ed end portions 20 of the display section end walls I9, and the inwardly sloping portion 2I of 'the upper end walls I0 may form an angle of approximately 62 deg. thereto.

It has been stated that the cooling coil 3 which is located in the top of the cabinet A is an oversize coil, and occupies the major portion ofithe top compartment or cooling section I, and in practice the-cooling coil 3 has a B. .t. u; capacity 4 operates the coil, the coil and the compressor being so proportioned that the coil condenses moisture from the surrounding air but without frosting. The resulting cooled air for example at a temperature of 34 deg. to 44 deg. being relatively heavy gravitatesvdownwardly through the cooling section I, and passes through the restricted throat of the cooling compartment I and is divided by the screen I3, a portion of the cool air passing beneath the screen I3 and over the riifled bafile plate'9 and the greater portion of this cool air passes over the screen I3 and I throughout the commodities placed thereon. The

of substantially 50 percent abovethe Bat. 11.

capacity of the compressor (not shown) which baffle plate 9 is a continuous plate but terminates short of the front wall of thebottom section or compartment 2 to leave an opening 22 through which the air passes by gravity into the bottom compartment 2. This air has given up a portion of it's cold and moisture to the fruit and vegetables on the screen I3, but has absorbed further moisture from the riffie held pools in passage 24 to maintain its moisture content and passes through opening 22 into the bottom warm air compartment from which it rises through passage 8 and passes into the cooling compartment and through the cooling coil 3. The air in the display cabinet A therefore is circulated continuously by convection currents and difference in densities between the cooled and warmer air. In practice, the air descendingfrom the cooling coil 3 is approximately 15 degrees cooler than the ascending air currents Thi circulation is effected by convection currents set up by the difference in the specific gravities of the cooler air passing from the coil 3 and the relatively warmer air which ascends as the cooler air descends, and by the arrangement of the baiile plates. The screen I3 forms an opening 23 between its inner end and the vertical wall 5, the cool air from the. coil 3 dividing so that a portion thereof passes over the screen I3 and a portion thereof passes through space 24 between the bottom of screen I3 and the top of the riilled bafile plate 9. The screen I3 and the bafiie plate 9 are disposed close and substantially parallel to eachother, and are inclined downwardly at an angle in excess of the normal angle of repose of the fruit and vegetables displayed on the screen I3, so that as such commodities are removed by the purchases of customers,

the remaining commodities gravitationally move downwardly against the end glass abutment I4. This angle of inclination of the screen I3 and the baffle plate 9 also permits the heavier cool air to pass therealong as a slow but steady current above and around and in intimate contact with the commodities on screen I3.- As these air currents reach the opening 22 between the outer end of the baflie plate 9 and front wall I2, the air current above the screen descending through and between the commodities to mix'with the current in'the space 24 between the screen I3 and the baffle, plate 9, and thismixed air passes into the bottom compartment 2-, it being now somewhat warmer so that it ascends through the rear passage or duct 8 that opens into the compartment 2. It will be understood that the passage 8 is of a size relative to the throat 5' to accommodate the ascending warm air from compartment 2. It is found in practice that virtually no outside atmospheric air mixes with the current of cool air passing downwardly over the screen I3, so that in practice a temperature differential-of about 15 degrees is maintained between the descending cooler air and the ascending warmer air a continuous, closed circulation cycle being thus maintained without forced draft circulating instrumentalities, as long as the coil 3 is operating.

It has been found in practice that a temperature of 44 deg. F., is the optimum temperature forthe air passing from the coil 3, and the coil 3 is operated from such temperature to 34 deg. accordingly. This temperature effects condensation of moisture from the air circulating within the cabinet, and; in accordance with this invention, this condensation is utilized for maintain- 'ing the displayed fruits and vegetables in a proper and attractive hydrated condition during thedisplay thereof.- The condensate on the coil 3 doesnot freeze owing to the temperature of the cell being above the freezing point of water, but it builds up until it drips continuously fromthe coil 3 against the inclined inner surface of the front wall portion it adjacent itslovver end from which it is directed against the wall 5 by which it-issplashed or diffused a it is directed through throat 5 and carried by the air currents over and through the commodities supported on screen l3 and displayed in section l4. Furthermore, a portion of this condensate from the coil 3 drops on the splash plate or wall 5' and flows therealong onto the bafil'e plate 9 and-collects in pools behind the rifiies II. The air currents passing through the screen l3 and over the plate 9 reabsorb this condensateso that the moisture content of; the air circulating in the cabinet A will bemaintained substantially constant, and the commodities onthescreen i3 will be maintained satisfactorily hydrated, without the necessity of recourse to water sprays or other extraneous source of water supply. If the humidity of the circulatingair-is very high, some condensate may collect in the bottomof the lower compartment 2, and consequently a trap may be provided for withdrawing any such collected condensate.

The bottom compartment 2 is free from forced air-circulating instrumentalities or any other extraneous equipment andconsequently'may be utilized for storage purposes. A heat insulated door-26 may be. provided for enabling access to be: had to the interior of the compartment.

It will be seen from the foregoing description thattheiinvention provides animproved opendisplay cabinet which effectively displays and preserves foodi commodities which are maintained ina-uniformlyfresh and hydrated condition and readily. accessible for self-service to customers, there; being maintained. a continuous circulation of; humidified; ain over and around the commodities, the: cabinet being free from moving partsor mechanism, or extraneou equipment. The. illustrated embodiment of'the construction whichincludesthe-features of the invention is a. preferrediorm which has" been accepted very popularly on the commercial market. However, it-will be apparent that the improvements of the invention: are. not limited necessarily to the specifically-illustrated and described embodiment, but structuraldetails can be varied without departing from the spirit of the invention, and, accordingly, it will be understoodand desired to embrace within the scope of the invention such modifications and changes as maybenecessary to adapt-it to varying conditions and uses, as defined in theappended claims.-

Having thus described-my invention, what I desireprotected by Letters Patentis as set forth in the following claims:

1. Anopentop cabinet for displaying perishablewfood commodities, comprising atop compartment and a bottom compartment, air cooling means in the top compartment operated ate. temperature belowthe dew point of air in the cabinet but above the freezing temperature of water, the cooling means producing active circulation of cooled and moisture-bearing air through the cabinet by convection currents maintained by diiferences in density between relatively cool and relatively warm air, an open display member for the commodities, means for directing convection currents of cool moisturebearing air from the cooling means over and around the commodities on thedi'splay member, means for directing the currents of cool and partially do -humidified air-downwardly by gravity into the bottom compartment after circulation around the commodities, and means communicating with the bottom. compartment for leading convection currents of relatively warm. air up- Wardly from the bottom: compartment to the cooling means.

2. An open top cabinet for displaying perishable food commodities, which comprises in combination, a. cabinet. defining av top air-cooling compartment and a bottom compartment. communicating with the topcompartment, air cooling means in the topxcompartment operated: at a temperature below the dew point of air in the cabinet but above the freezing temperature of water, the. cooling means producing active circulation of cooled and moisture-bearing air through the cabinet by convection: currents maintained by differences in densitybetween relatively cool and relatively warm air, an open display member for the commodities communicating with the top compartment forreceiving cooled air from the compartment, the said member sloping downwardly from thecompartment at an angle enabling moisture-bearing cooled air to ilow along the member by gravity and in intimatecontact with commodities on the member for cooling and moisteningthe commodities, an air passageway communicating between the member and the bottom compartment for receiving gravitationally descending air currents from the commodities and for raising the temperature of the air slightly abovethe temperature of the descending air currents, thereby creating convection air currents in the cabinet, and means for leading convection currents of ascending warmer air currents into the cooling compartment, thereby continuously circulating cooled and moisture-bearing air over thecommoditiesand through the cabinet while avoiding mechanical circulating instrumentalities.

3. A self service cabinet for displaying and humidifying' perishable food commodities, comprising a cabinet defining a top air-cooling compartment and a bottom compartment, air-cooling means in the top compartment operated at a temperaturebelow thedew pointof air in=the cabinet but abovethe freezing temperature of water for collecting'liquid water condensate on the coolingmeans, an open, reticulated conimodity-displaying member communicating with thetop compartment for receiving gravitationally descendingcooled air therefrom and. liquid condensate dropping-from the cooling-means, the said reticulated member sloping downwardly from the compartment at an angle enabling cooled air to flow gravitationally along thememher and in intimate contact with commodities displayed thereon and to render sucli' commodities fully visible to a purchaser; abattle-plate mounted adjacentto and'beneath thereticulatcd member and defining an air passage therebetween communicating with the top compartment, means in the top compartment adapted to direct cooled air and condensate from the cooling means onto the reticulated member and the baffle plate, a plurality of rifiles on the baffle plate adapted to collect pools of condensate from the cooling means, the resulting pools of condensate being in contact with descending cooled and partially dehydrated air from the cooling means for humidifying the commodities and for re-humidifying the cooled air, the reticulated member and baflle plate terminating in a port communicating with the said air passageway and with the bottom cabinet compartment for gravitationally leading cooled and re-humidified air from the commodities into the bottom compartment for slightly raising the temperature of the air in the bottom compartment, and air duct means leading from the bottom compartment for enabling warmer air therein to rise by convection into the top compartment for re-cooling and gravitationally recycling the said air.

4. An open, self-service cabinet for displaying and humidifying perishable food commodities, which comprises, in combination, a cabinet having a closed top and a closed bottom, air-cooling means in the top of the cabinet operated at a temperature below the dew point of air in the cabinet but above the freezing temperature of water for condensing and collecting moisture from the air as liquid condensate, the cooling means producing active circulation of cooled and moisture-bearing air through the cabinet solely by convection currents maintained by differences in density between relatively cool and relatively warm air, a substantially vertically disposed splash plate mounted intermediate the cooling means and back of the cabinet and spaced from both, an open, reticulated commodity-displaying member angularly disposed downwardly from beneath the cooling means to a lower front wall of the cabinet, the said member having a slope enablingfull viewing of the commodities thereon by a purchaser and enabling cooled air from the cooling means and liquid condensate directed against said splash plate to circulate by gravity over and around the commodities supported on the reticulated member to flow by gravity downwardly therethrough, a baffle plate disposed beneath the reticulated member and spaced therefrom in substantially parallelism therewith, the baflle plate being in engagement with the splash plate for also receiving a portion of the liquid condensate from the splash plate, means on the bafile plate for collecting liquid condensate in the space between the baffle plate and reticulated member, the said space defining a passage for convection currents of the cooled air descending from the cooling means in contact With the commodities, means enabling cooled air from the reticulated member and air passage therebeneath to pass by gravity to the bottom portion of the cabinet where the said air becomes somewhat warmer than the descending cooled air, and means for leading the resulting warmer air solely by convection upwardly from the bottom portion of the cabinet into engagement with the cooling means in the top portion thereof.

5. An open, self-service cabinet for displaying and humidifying perishable food commodities, which comprises, in combination, a cabinet having closed top and closed bottom portions, air cooling means in the top portion operated at a temperature below the dew point of air in the cabinet but above the freezing temperature of water for' condensing and collecting moisture from the air as liquid condensate, the cooling means producing active circulation of cooled and moisture-bearing air through the cabinet solely by convection currents maintained by differences in density between relatively cool and relatively warm air, a substantially vertically disposed splash plate mounted intermediate the cooling means and back of the cabinet and spaced from both, the said plate terminating short of both top and bottom of the cabinet, an angularly disposed surface forming with said splash plate a restricted passage below said cooling means, an open, reticulated commodity-displaying member angularly mounted on the cabinet and sloping downwardly and outwardly from beneath said restricted passage at an angle enabling full viewing of the commodities displayed thereon by a purchaser, said angularly disposed surface being adapted to direct the liquid condensate drippings from the cooling means against the splash plate from which a portion is directed into the path of the descending cool air and through said restricted passage and over and around said commodities humidifying the same, a baiiie plate connected to said splash plate extending beneath said reticulated member and forming therewith a passageway through which is directed a portion of the condensate and air from the cooling means, means on the baiile plate for collecting pools of the liquid condensate, the resulting pools being engaged by air currents gravitationally passing through the reticulated member and the air passageway for re-humidifying the said air. the baffie plate defining a top closure for the bottom portion of the cabinet, and means enabling cooled and re-humidified air to pass by gravity-from the reticulated member and passageway into the bottom portion of the cabinet where the air is warmed slightly to a temperature somewhat above the descending colder air, the said splash plate defining with the back of the cabinet an air duct for enabling the warmer air from the bottom portion of the cabinet to rise by convection into contact with the cooling means for recycling over the commodities.

6. A display cabinet, including an open top display compartment adapted to contain-fresh food commodities, a cooling chamber above and in communication at its lower end with the display compartment, and a warm air chamber below the display compartment, an air return passage intercommunicating the warm air and cooling chambers, and a cooling means in the upper portion of said cooling chamber, the said cooling means producing active circulation of cooled and moisture-bearing air through the cabinet 'solely by convection currents maintained by differences in density between relatively cool and relatively warm air, whereby the air will be caused to circulate by convection from the warm air chamber to the cooling chamber, through the cooling means and pass over and through the contents of the display compartment, and into the warm air chamber, the cooling means being arranged so that condensate therefrom will be directed into the display compartment. 1

7. A display cabinet, including an open top display compartment adapted to contain fresh food commodities, a cooling chamber above and in communication at its lower end with thedisplay compartment, and a warm air chamber below the display compartment, an air return passage intercommunicating the warm air and cooling chambers, and a cooling means 1 =the, upper portion, Qf, said cooling chamber, the said cooling means-producing active circulation of cooled and moisture-bearing air through the cabinet ,solely .by convection currents initiated and maintained ,by difiierences in density between, relatively cool and relatively warm air, whereby the air will be caused to, circulate by convectionfrom thewarm air chamber to the cooling chamber, throughthe cooling means and pass over and through the contents of the display compartment and into the warm air chamber, said cooling chamber having a restricted passage at its lower end, the ararrangement of said passage and the cooling means being such thatthe condensate from said cooling means is diifusingly intermingled with the air particles and as they are directed into the display compartment.

8. An open, self-service cabinet for displaying and humidifying perishable food commodities, which comprises, in combinatioma cabinet having closed top and closed bottom portions, air cooling means in the top portion of the cabinet and closely adjacent to the closed top thereof, the said air cooling means being operated at a temperature below the dew point of air in the cabinet but above the freezing temperature of water for condensing and collecting moisture from the air as liquid condensate, the cooling means producing gravitational circulation of air through the cabinet from top to bottom thereof by difference in density between relatively cool and relatively warm air, a substantially vertically disposed splash plate mounted in the cabinet intermediate the cooling means and back of the cabinet and spaced from both, the said plate terminating short of both top and bottom of the cabinet, an angularly disposed bafile plate forming with the splash plate a restricted passage below the cooling means, an open, reticulated commodity-displaying member angularly mounted on the cabinet vertically spaced above the baffle plate and defining a restricted space between itself and the baffie plate, the said reticulated member sloping downwardly and outwardly from beneath the restricted passage at an angle enabling full viewing of the commodities displayed thereon by a purchaser, the said angularly disposed bafile plate being adapted to direct liquid condensate dripping from the cooling means against the reticulated member from which a portion is directed over and around the commodities humidifying the same, means enabling cooled and re-humidified air to pass by gravity from the reticulated member into the bottom portion of the cabinet where the air is warmed slightly to a temperature somewhat above that of the descending colder air, the said splash plate defining with the back of the cabinet and air duct for enabling the warmer air from the bottom portion of the cabinet to rise by convection into contact with the cooling means for recycling over the commodities, continuous circulation of air being efiected by convection only produced and continuously sustained by differences in specific gravity between the warmer ascending air and the cooler recooled and humidified air descending from the air cooling means in the top portion of the cabinet, the said recooled and humidified air passing solely by gravity downwardly from the cooling means and over and through the commodities being displayed, and reflecting means mounted longitudinally of the cabinet adjacent to the top thereof and in advance of the cooling means, the reflecting means being above the reticulated member and sloping at a complementary angle theretofor reflecting an extended image of the commodities viewed; by a purchaser, the reflect ing means defining an outer front side of the cabinet.

9. An open top cabinet for displaying perishable food commodities, comprising a cabinet defining a top air-cooling compartment and a bottom compartment, air cooling means inthe top compartment, the compartments being freely intercommunicating, an open reticulated commodity-displaying member communicating with the top compartment for gravitationally receiving cooled, moisture-bearing air therefrom, the said cooling means producing active circulation of cooled and moisture-bearing air through the cabinet by convection currents maintained by differences in density between relatively cool and relatively warm air, the said reticulated member sloping downwardly from the top compartment at an angle enabling cooled air to flow by gravity along the member and in intimate contact with the commodities displayed on the reticulated member, and to render such commodities fully visible to a purchaser, a baiile plate mounted to and beneath the reticulated member and defining an air passage therebetween communicating with the top compartment, the reticulated member and baflle plate terminating in a port communicating with the said air passageway and with the bottom cabinet for slightly raising the temperature of air therein, and air duct means leading from the bottom compartment to the top compartment for enabling warmer air in the bottom compartment to rise into the top compartment through less specific gravity than the cooled descending air for recooling and gravitationally recycling the said air.

10. An open, self-service cabinet for displaying and humidifying food commodities, which comprises, in combination, a cabinet having closed top and closed bottom portions, air cooling means in the top portion of the cabinet and closely adjacent to the closed top thereof, the said air cooling means being operated at a temperature below the dew point of air in the cabinet but above the freezing temperature of water for condensing and collecting moisture from the air as liquid condensate, the cooling means producing gravitational circulation of air through the cabinet from top to bottom thereof by difference in density between relatively cool and relatively warm air, a substantially vertically disposed splash plate mounted in the cabinet closely adjacent to the cooling means but intermediate the cooling means and back of the cabinet and spaced from both the said plate terminating short of both top and bottom of the cabinet, an open perforate commodity-displaying counter member angularly mounted on the cabinet and sloping downwardly and outwardly at an angle permitting full viewing of the commodities displayed thereon, means directing condensate from the cooling means onto the commodities as cooled and dehumidified air from the cooling means descends gravitationally from the cooling means onto the commodities and flows over and through the commodities into the bottom portion of the cabinet, the commodity-displaying counter member communicating with the said bottom portion of the cabinet where the air is warmed slightly to a temperature somewhat above that of the descending cooler air, the said splash plate defining with the back of the cabinet an air duct for enabling the warmer air from the bottom portion of the cabinet to rise by convection into contact with the cooling means DAVID FRANKLIN WILLIAMS. JAMES DONALD WILLIAMS. 7

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

Number 12 UNITED STATES PATENTS Name Date Monette Feb. 28, 1911 McCord Nov. 15, 1932 Gardner June 8, 1937 Caulk Aug. 14, 1945 Tully June 21, 1949 Henderson Dec. 27, 1949 MacMaster Jan. 10, 1950

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