US2870829A - Radiant heat fuel burner - Google Patents

Description

Jan. 27, 1959 J. R. WILLIAMS 2,870,829

RADIANT HEAT FUEL BURNER Filed March 26, 1954 3 Sheets-Sheet 2 mmvroze: Job/2 Raga MZ/z'ams,

BY I PMJ' ATTORNEYS.

Jan. 1959 I J. R. WILLIAMS 2,870,829

RADIANT HEAT FUEL BURNER File d March 26, 195 3 Sheets-Sheet :5

VA PIA 8L 5 P/PfSSZ/REGAS PIQESSUREJ'MTCH FOP ISM/4067' FAN H614. I 91 6 102 101 100 \\\Q$ g 6/ A 205 2] g 93 INVEIYTOR.

7 9 70 Y wfizzfiagenWzlZzams,

A TTORNEYS.

United States Patent a RADIANT HEAT FUEL BURNER John Roger Williams, Ambler, 1 s., assignor to Selas Corporation of America, Philadelphia, Pa., a corporation of Pennsylvania Application March 26, 1954,Serial No. 418,858 12 Claims. cI.1ss- 11s This invention relates to a radiant heat fuel burner,

and more specifically concerns a domestic type gas burner. The invention is descfibed herein as being used with a gas stove or range by way of exampleonly since that is one of its principal uses.

i It is an object of this invention to provide a fuel burner which utilizes the radiant heat principle to furnish intense heat to cooking utensils and other articles. Another object is to provide a kitchen stove or range of the gas burning type, wherein means are provided for processing or disposing of the products of combustion in any desired mannerbefore they enter the room where the stove is located. a

Still another object of this invention is to provide a radiant heat gas burner which withdraws the air from the vicinity of a kitchen range and utilizes that air for burning the gas, thereby reducing or Completely eliminating cooking odors inthe mom, t i

It is a still further object of this invention tb provide a radiant heat gas burner for a kitchen stove or range having aeovered construction protecting the gas burner parts from spilled foods, etc. Still another object of this invention is to provide a gas burning range having a substantially smooth, fiat topwh'ich' is easily cleaned.

Another object of this invention are pfovide a gas burner of improved etficiency and which is strong, co'mpact and economical to manufacture. d

Other objects and advantages of this invention will appear in further detail hereinafter, and in the drawings whereof: U i

Fig. 1 represents a central vertical sectional viewer one specific gas burner construction whichenibodiesifeawas of this invention;

Fig. 2 rp't'esents a View in side elevation of the pper portion of the radiant heat gas burner of Fig. 1,;i11ustrating the means whereby the gas burner is installed in a kitchen stove or'r'ang'e; i f

Fig. 3 represents a fragmentary enlarged sectional view of an upper edge portion of the radiant heatgas'burner illustrated in Fig. 1; w A

Fig. 4 represents a'view similar to Fig. 3 showing a modified cohstriictioh; i Fig. 5 represents a burner inusaatedin Fig. J1, withpar'ts broken awa order more particularly to illustrate important details;

Fig. 6 represents a sectional view taken as indicated by the lines and arrows VI-VI which appearisuigqr;

Fig. 7 represents an exploded view-in perspective bfthe means for feeding gas and air to the radiant heat gas burner illustrated in 1; and d Fig. 8 represents a diagrammatic view"illii'stratingthe preferred ai 'rangerneht and operation of the i'adianttheat gas burner for service in a kitcheii stove or range. I

Turning now to the specific enibodiinentsof.the'invdiition selected for illustiation the drawings, the arrangement of the component parts of'theai paratus willffit'st be discussed. The-number "20 in Fig. 1 designates comprehensively a radiant heatgas burner including a rfi'actoiy discorbed 21. 3 Spaced aboveth'ebed ll is (a substantiallyparallel "cdver 22 fa nted or raaiantheattraasmitting material, preferably glass. Bed 21 and cover22 plan view of the radiant heat .gas.

engage one another around their peripheral edge, forming an intervening combustion space 23. Feed means comprehensively designated 24 are provided for feeding gas and air into substantially the center of combustion space 23, and an exhaust pipe 26 is connected to an exhaust fan or blower 25 (Fig. 8) to create a pressure diiferential across the burner. The gas flame heats the surface of refractory bed 21 to incandescence, and the resulting intense radiant heat is directed upwardly through the cover 22. Cover 22 is also heated by conduction, and the resulting radiant heat and conductive heat coact to heat rapidly any kitchen utensil or other article that is located on top of the cover 22.

Fig. 8 of the drawings illustrates diagrammatically a preferred arrangement of the gas burner components in a kitchen stove or range. The radiant heat gas burner 20 is connected toa gas manifold 30 through a main control valve 31 which serves to turn the gas burner on and off. Gas from manifold 30 flows through a variable pressure gas line 38 to an inspirator 32 which forms a partial premix of gas and air, and the partial premix flows through a venturi 33 into the burner, where it is mixed with fan-induced secondary air and burned.

Control valve 31, when opened either partially or completely, always admits gas under full line pressure to a pressure tube 34. Valves of such construction are conventional, do not of themselves constitute any part of this invention, and are not further illustrated in the drawings. The full line pressure in tube 34 operates a pressure switch 35 which is electrically connected to start the exhaust fan 25. The full line pressure in tube 34 also operates another pressure switch 36 which is electrically connected to energize an ignition wire 37 to light a pilot 6h. Flame from the pilot 60 flashes across a "flash tube ,61 and travels upan inclined ladder 62 to light the burner 20. A thermal switch 43' then opens .the circuit through ignition wire 37. When the main control valve 31 is closed, the flame in gas burner 20 is extinguished and the exhaust fan continues to operate for a few seconds until the gas at switch 35 drops to a predetermined pressure whereupon the switch 35 opens, shutting down the exhaust fan 25. The foregoing ar- Jrange, wherein the gas from pressure switch 35 passes out through small'openings in the pilot and ladder, contributes a time delay which is advantageous in that the blower purges the combustion space 23 by operating for a brief period of time after the gas flame is turned off.

The construction and arrangement of the radiant heat gas burner 20.will now be described in detail. Referring first to Fig. l of the drawings, the radiant heat gas burner 20 is, supported on a plate 40, comprising a part of the kitchen stove. or range structure, on a standard 41 having legs 42. Secured tothe tops of legs 42 is a manifold 43 having achamber 44 containing a partial premix consisting of gas and air. The partial premix, which is too rich to burn or explode, is fed to the annular chamber 44 through the inspirator 32 and venturi 33 from the variable pressure gas line 38.

Supported on an internally formed shoulder 45 at the top of manifold 43 is a vertically arranged sleeve l6 (see also ,Fig. 7), the top of which is provided with a plurality ofradially extending grooves 47. Spaced be low the grooves 47 on sleeve 46 are four smalhradial bores 50. Below the bores 50 the outside of sleeve 46 has a .pair of shoulders 51, 52. Shoulder 51 supports a'ringj53 which islspaced outwardly away from the upper portion of sleeve 46 through which the bores 50 extend. An intervening pilot chamber 54 is thereby formed. Partialpremix, flowing out through bores 59, enters the combustion space 23 from chamber 54, piloting the gas flame in combu's'tion space 23.

A central tube 55 is suspended by a flange 56 at its 9 upper end from the top of sleeve 46. It is concentric with sleeve 46 and with the manifold 43, and its lower end extends through a central opening formed in manifold 43. The outside surface of tube 55 comprises the inner surface of an annular passage 57 up Which'the partial premix flows. Secondary air flows upwardly in side the tube 55, this movement being inducedby exhaust fan 25, as will further appear.

Flange 56 extends over the tops of grooves 47, forming a plurality of radial passages through which the partial premix of gas and air passes into the combustion space 23. The fan-induced secondary air passes over the top of flange 56 and mixes with the partial premix at and beyond the outer edge of flange 56, producing'a combustible mixture.

Means are provided for igniting the combustible mixture. This means includes the pilot 60, flash tube 61 and ladder 62, previously referred to. From Figs. 1 and 8 it will be apparent that the ladder 62 comprises an inspirator'and an inclined tube having a longitudinally arranged slot 64. The refractory bed 21 is provided with an opening 65 through which the flame from ladder 62 extends. The flame from ladder 62 is located near enough to the edge of flange 56 to ignite the mixture of fan-induced air and partial premix, creating the main burner flame.

Means are provided for inducing the flow of secondary air and for withdrawing the products of combustion from the combustion space 23. The refractory bed 21 and cover 22 are both supported on a generally ring shaped exhaustcollector 70. Collector 70 is supported on arms 71 seated on a shoulder 72 on the manifold 43. The upper portion of exhaust collector 70 includes a floor 73 and a side wall 74 forming a tray for the refractory bed 21. The bed 21 is provided, at equally spaced points all around its periphery, with a plurality of vertically extend- ,munication between combustion space 23 and exhaust collector 70. The exhaust pipe 26 is connected into the bottom 77 of exhaust collector 70, and extends concentrically into or adjacent the end of a sleeve 80 of larger diameter. Sleeve 80, as appears in Fig. 8, is slidably car 'ried by a duct 81 which is connected to the intake of exhaust fan 25. Because of the space between pipe 26 and sleeve 80, the fan 25 draws air between them. The air mixes with the hot combustion pro-ducts, reducing the temperature of the mixture to be handled by the fan 25. This feature eliminates the need for a specially constructed, high-temperature fan.

The adjustable character of sleeve 80 also provides a means of controlling the proportion of secondary air in the combustible mixture. When sleeve 80 is withdrawn from the end of exhaust pipe 26 its suction effect is slight. inducing only a slight flow of secondary air. On'the other hand, when sleeve 80 is moved closer to the end of pipe 26, its suction effect increases, thereby increasing the proportion of secondary air.

It will accordingly be appreciated that the gas flame and combustion products flow substantially radially outwardly from the center to the periphery of bed 21. A baflie plate 82 is provided in manifold 70 above the exhaust pipe 26 to distribute the flow, preventing excessive flow above the exhaust pipe 26. Baffle plate 82, as shown, extends half way around the manifold 70 and is centered above exhaust pipe 26.

Means are provided on the refractory bed 21 for distributing the flame and the flow of combustion products. Figs. 1 and disclose a plurality of radially-extending upstanding ribs 83 which are preferably refractory material formed integrally with the bed. Ribs 83 are much thinner than the bed, and are quickly brought to incandescence by the flame and hot combustion products. Ribs outer edge.

83 are arranged in a plurality of circles concentric with the central opening in bed 21, and are circumferentially staggered relative to one another, causing the combustion mixture to follow tortuous paths in the combustion space 23. The tops of all the ribs 83 are preferably substantial 1y equally spaced below the bottom surface of cover 22. As shown, the ribs in each circular arrangement are equal 1y spaced from one another, but the rib spacing varies from circle to circle.

The shape of the upper surface of refractory bed 21, as shown in Fig. 1, is an advantageous feature of this invention. It will be noted that the surface curves up-- wardly at 84 from the inner edge, that a central portion 85 is substantially level, and that an outer portion 86 curves downwardly from the centralportion 85 to the Expressedin broader terms, the surface of the refractory bed is preferably crowned, by which is meant curved upwardly and then downwardly in such a manner that the flow of combustion products is concert trated in the area adjacent to the upper surface of the refractory bed 21.. In this connection, it is important to observe that the grooves 47 through which the partial pro mix is fed are all located at about the level of the inner edge of refractory bed 21, preferably slightly above it. With this arrangement the outside of the flame, which is the hottest part of it, sweeps the refractory surface. Moreover, the combustion products are withdrawn through passages 75 at the level of the outer periphery of the refractory bed 21. And the fan-in-duced secondary air from tube 55 is admitted to the combustion space above the level of introduction of the partial premix; the secondary air tends to urge the flame down against the upper surface of the refractory bed. All these features coact with one another to concentrate the hottest part of the flame where it is most effective, namely, adjacent to the surface .of the refractory bed.

Means are provided for enclosing the combustion space 23 between the cover 22 and the refractory bed 21. The peripheral edge of the refractory bed comprises a rim 90 on which is seated an internal shoulder 91 formed on the bottom surface of the cover 22. The cover 22 has a peripheral flange 92 which seats on the top plate 93 of manifold 70. The side wall 94 of exhaust collector 70 carries tongues 95 which extend into slots 96 formed in a side wall 97 of a sealing ring 100. The top 101 of ring is substantially horizontal. It is supported on a shoulder 102 on cover 22, and held down by tongues 95 which extend into slots 96. Because of the substantially sealed construction of the burner, foods or liquids spilled on cover'22, sealing ring 100, or the top of the range are prevented from contaminating the operating parts of the gas burner. Such foods or liquids are easily removed from the upper surfaces of the kitchen stove or range.

Figs. 2 and 3 of the drawings illustrate clips 104 which are secured to wall 94 and extend into recesses 105 formed in cover 22. Clips 104 are desirable' in that they secure the cover 22 to the rim 90 of the refractory bed, and to the top 93 of manifold 70.

Fig. 4 shows a modified form wherein the top of exhaust collector 70 includes an inner upstanding rim 106 which excludes spilled liquids from the refractory bed 21. In the embodiment of the invention illustrated in Fig. 4, the cover 22 rests by gravity on the top of exhaust collector 70, and the sealing ring 100 rests by gravity on the cover 22. It will be appreciated that slight air leakage into the periphery of combustion space 23 is not detrimental, since theair is immediately drawn out through the vertical passages 75 and does not appreciably cool the incandescent surface of refractory bed 21.

Fig.6 discloses further details of inspirator 32, indicating the arrangement wherein the incoming gas is projected through a nozzle or gas spud 110 through a chamher 111 and into the venturi 33. Air is drawn inthrough the opening 112 at the top of the inspirator body, the

r b size of the opening 1I2 being adjusted by a valve plate 113 which is pivoted to the inspirator at 114. Fig. '6 also shows that the inside wall of exhaust collector 70 includes anoutwardly extended portion 115 located diametrically opposite to the exhaust pipe 26, thereby providing clearance space for the inclinedladder 62.

In the operation of the radiant heat gas burner disclosed herein, the exhaust fan and pilot are automatically actuated in response to the opening movement of the burner gas valve, and the main burner flame 'is automatically lighted and drawn radially across the refractory bed. The heat of combustion quickly brings the refractory ribs 83 to incandescence, and the ribs pr'oject intense radiant heat, as well as heat of conduction, upwardly through the transparent cover 22. After further operation of the burner, theentire surface of the refractory bed is uniformly heated to incandescence. The combined radiant and conductive heat thereby developed penetrates the cover with greater intensity and at a more rapid rate than the heat produced by conventional gas burners. And, particularly when heating a utensil having a large, flat bottom surface, a burner in accordance with this invention provides more usable heat per B. t. u. consumed.

The products of combustion may be disposed of in i any desired manner. They are preferably carried through a duct extending outside the building in which the fuel burner is located. However, in connection with kitchen stoves or ranges the combustion products may be discharged from the burner into the kitchen, or piped to any other desired location. The combustion products may be propelled through a heat exchanger to convert some of the heat of combustion to useful work. Other advantageous arrangements will readily becomeapparent.

Although the cover piece 22 may consist of one of many various materials which have capacity to transmit radiant heat, it is preferred to utilize special, transparcut or translucent glasses which are highly resistant to thermal shock. One such glass, which is commercially known as Vycor, is resistant to the shock of immersion in ice water at 1800 F., and is a desirable material in view of its capacity to transmit radiant heat. Another material that may be used is quartz.

lt will be apparent that kitchen stoves using the covered burners of this invention have flush tops, which have a trim and pleasing appearance and are easy to clean. Covered radiant heat gas burners in accordance with this invention are not only much easier to keep clean than conventional gas burners, but they also permit the use of a simplified stove construction. ventional stoves require drip pans to take careof materials spilled into the burners, these are not required with covered radiant heat burners in accordance with this invention.

Covered radiant heat gas burners have the further advantage that they may be located near or under windows, where breezes or drafts tend to extinguish the gas flames in ordinary burners.

It will be appreciated that the glass cover and the refractory bed may be shaped in a variety of ways. For example, the glass cover may be shaped like a .dish,having a vertical or inclined sidewall; The refractory bed may also be dish shaped, uniformly spaced from the glass, the combustion products withdrawn from the upper periphery of the intervening combustion space. Other such arrangements will readily occur to persons skilled in the radiant heat art.

While it is preferred to utilize a cover consisting entirely of heat-resistant glass, the cover may be only partly glass set into a metal plate or the like.

Radiant heat gas burners in accordance with this invention may be used as oven burners, either upright, inverted, or mountedin a side wall of the oven. Kitchen ranges may, of course, be designed with radiant heat stove bilrners and a conventional oven nurses, or all the burn- While coners maybe constructed and operated in accordance with this invention.

Although thisinvention has been" described by reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes other that those referred to above may be made in the form of the device, that equivalent elements may be substituted for those illustrated in the drawings, and that certain features of the inventionr'nay be used to advantage independently ofthe use of other features, all within the spirit of the invention as defined inthe appended claims.

Having thus described my invention, I claim:

1. A unit type radiant heat fuelburner for a range comprising a substantially horizontal refractory b ed having a central opening therein, a one piece, substantially flat heat transmitting cover spaced from said bed forming a substantially flat combustion space between said cover and bed, a hollow annular body to support said bed and cover, means forming a plurality of ports in said bed andbody, said ports extending between said tm l space and the interior of said body around and adjacent to the outer edge of said space, a sealing ring engaging said cover to fasten said cover to 'said body to enclose and substantially seal said combustion space, meansfo'r feeding gas and means for feeding air through said central opening, means for igniting and burning the gas and air in said enclosed combustion space, a suction fan, and means to connect saidfan to the interior of said body to withdraw the combustion products from all around the outer edge of said combustion space through said ports at a multiplicity of points} 2. A unit type radiant heat gas burner for a range comprising a refractory bed having 'a substantially circular upper surface, a substantially circular heat transmitting cover of one piece construction, supporting means having an annular surface and an annular shoulder surrounding said surface and spaced axially therefrom, said bed resting on said surface and said cover resting on said shoulder, means fastening said supporting means, bed and cover together to form an enclosed combustion space between said bed and cover, means forming an annular chamber on said supporting surface below said combustionsp'ace, means forming a multiplicity of ports extending between said chamber and said space around and adjacent to the periphery of the latter, said bed having a substantially central opening, means for feeding gas and air in concentric streams through said opening, means for burning the gas and air in said enclosed combustion space, a fan and means to connect said fan to said chamber for withdrawing the combustion products through said bed from said rnultiplicity of ports spaced all around the periphery of said bed whereby the gas and air burns as it moves radially over substantially the entire area of said bed, said bed having a plurality of ribs upstanding from said upper surface foiming in said combustion space a plurality of passages for the combustible mixture flowing radially from said central opening to the periphery of said refractory bed.

3. The radiant heat gas burner defined in claim 2, wherein said ribs extend substantially radially and are circumferentiaily staggered relative to one another, causing the combustion mixture to follow tortuous paths as it flows through said combustion space.

4. The radiant heat gas burner defined in claim 3, wherein the ribs are arranged as a series of circles concentric with said central opening, the ribs being uniformly spaced apart from one another in each circle.

5; The radiant heat gas burner defined in claim 4,

wherein the spacing between said ribs in one of said circles is difierent from the spacing between said ribs in another of said circles.

6. The radiant heat gas burner defined in claim 2, wherein the ribs arev radially arranged, circumferentially staggered, and consist of refractory material, the tops of said ribs all being substantially equally spaced from the bottom surface of said cover.

7. Arunit type radiant heat gas burner for a range comprising a refractory ring, a one piece heat transmitting cover spaced above said ring forming an intervening combustion space, said ring having an upper surface, supporting means having a pair of axially'displaced surfaces upon which said ring and cover are received, means to clamp said ring, cover and supporting means together to enclose and substantially seal said combustion space, means for separately feeding gas and air in concentric streams into said combustion space at the center of said ring and at substantially the level of the inner edge of said upper surface, means forming an annular collecting chamber below said ring, means forming a multiplicity of ports between said space and chamber and extending through said ring adjacent to and around the periphery thereof, suction means, and means to connect said suction means to said chamber for withdrawing the combustion products through said ring at said multiplicity of ports spaced all around the periphery of said ring and substantially at the level of the outer edge of said upper surface, whereby the flow of hot combustion products is radially outward across susbtantially the entire upper surface of said ring and is concentrated in the space adjacent to said surface of said refractory ring.

8. In a kitchen stove or range the combination comprising a unit type radiant heat gas burner including a refractory bed and a heat transmitting cover, means to space said cover from said bed to form an intervening enclosed combustion space, means engaging said cover and bed substantially to seal said space, a source of gas under pressure, feed means connecting said source to said combustion space, electrically operated exhaust means connected to remove the combustion products from said enclosed combustion space, an adjustable valve connected into said feed means to control the pressure of said gas, pilot burner means for igniting the gas in said combustion space, a supply line connected from said adjustable valve to said pilot burner means, said valve being constructed to admit gas under pressure to said supply line whenever gas is being fed to said combustion space,'a pressure operated switch connected into said supply line and means to connect said switch to said exhaust means to actuate said exhaust means in response to the operation of said adjustable valve. 3

9. A unit type radiant heat gas burner for a range comprising a refractory ring having a plurality of openings spaced all around its periphery, a heat transmitting cover, hollow annular supporting means to space said cover from said ring to form an intervening combustion space, said means including a pair of axially displaced supporting surfaces upon which said ring and cover rest, the surface upon which said ring rests being provided with a plurality of openings communicating with the interior of said annular supporting means and substantially aligned with the openings in said ring, means surrounding said cover and engaging said cover and annular supporting means to enclose and substantially seal said combustion space, mixing means for forming a partial premix of gas and air, means for feeding said partial premix to said combustion space around the edge of the central opening of said ring, means for feeding air into said combustion space concentric with said partial premix,

said partial premix and air combining to form a combustible mixture in said combustion space, a suction fan and means to connect said fan to the interior of said annular supporting means for withdrawing the combustion productsthrough said openings from said space at a multiplicity of points spaced around and adjacent to the periphery of said ring.

10. A unit type radiant heat gas burner for a range comprising a refractory ring, a heat transmitting cover, a body having an annular chamber supporting said ring and cover and including a surface upon which each one rests to space said cover from said ring to form an intervening combustion space, a sealing ring engaging said cover and body to fasten, said cover to said body to enclose and substantially seal said combustion space, means forming a plurality of ports between said chamber and space, said ports extending through said ring adjacent to and around the periphery thereof a manifold including a gas passage for feeding gas to the center of said combustion space, means including an air passage adjacent to said gas passage for feeding aid concentrically to the gas at the center of said combustion space, means for igniting said gas and air in said combustion space, and moving means including a suction fan and means to connect said fan to said annular chamber for concurrently inducing the air feed into and withdrawing the combustion products from said combustion space through said plurality of ports spaced radially from the center thereof and all around the periphery of said space.

11. The radiant heat gas burner defined in claim 10 wherein means are provided for forming a partial premix of gas and air and for feeding said partial premix into said gas passage, and wherein the air in said air passage is secondary air required to support combustion of said partial premix.

12. In a unit type burner for a kitchen stove, the combination of an annular refractory plate, having a plurality of openings extending therethrough adjacent to and around its periphery, a one piece heat transmitting cover, supporting means having surfaces upon which said plate and cover rest to hold said cover over and spaced from said plate to form a thin intervening combustion space, ring shaped clamp means closely engaging said supporting means and cover to clamp them together and substantially to seal said combustion space, means to introduce a gaseous fuel into said combustion space around the center opening of said plate, means to introduce air to said combustion space through the center opening of said plate concentric with the fuel, the fuel and air burning in said combustion space, means forming an annular duct on said supporting means, said duct being in communication with said combustion space through the openings in said plate, suction fan, means to connect said suction fan with said duct whereby the flow of air will force the fuel against the surface of said plate while they are flowing radially through said combustion space during the process of combustion.

References Cited in the file of this patent UNITED STATES PATENTS 551,715 Brook Dec. 17, 1895 1,345,361 Good July 6, 1920 1,635,634 Pohl July 12, 1927 1,735,654 ODowd Nov. 12, 1929 1,736.24] Aird Nov. 19, 1929 2,215,079 Hess Sept. 17, 1940 2,241,661 Furlong May 13, 1941 2,287,246 Hess June 23, 1942 2,319,131 Harrington May 11, 1943 2,362,247 Converse Nov. 7, 1944 2,491,000 Cone Dec.13, 1949 I 2,526,748 Hill Oct. 24, 1950 2,547,276 Marsh Apr. 3, 1951 2,570,554 Henwood Oct. 9, 1951 2,608,245 Clark Aug. 26, 1952 2,663,362 Ransome Dec. 22, 1953 2,735,483 Brodbeck et a1. Feb. 21, 1956 2,806,465 Hess Sept. 17, 1957 FOREIGN PATENTS 797,619 France Feb. 17, 1936 976,678 France Nov. 1, 1950 136,626 Great Britain Dec. 17, 1919 284,289 Great Britain Oct. 11, 1928 564,754 Germany Nov. 22, 1932 796,780 France Jan. 27, 1936

Images