US2622222A - Infrared heating and cooking lamp - Google Patents

Description

Dec. 16, 1952 A. M. HAGEMAN ETAL 2,622,222

INFRARED HEATING AND cooxmc LAMP Filed April 27, 1951 Patented Dec. 16, 1952 UNITED STATES PATENT OFFICE INFRARED HEATING AND COOKING LAMP vania Application April 27, 1951, Serial No. 223,232

6 Claims. 1

This invention relates to lamps and, more particularly, to infra-red heating and cooking lamps.

A possibility in the present design of electric cooking ranges is the substitution of infra-red heating and cooking lamps for the conventional resistance-type heating plates. The advantages of the cooking lamp are more rapid heating, as as well as visual indication to the user of the stove that the source of heat is alive. Another advantage of the cooking lamp is the ease of replacement by the user of the stove.

Disadvantages in the use of the cooking lamp, as a replacement for a resistance-type heating plate, lie in the high cost of manufacture of such a lamp due to the large and expensive graded seals used to join the Vycor or quartz bulb to a conventional relatively softer glass, such as Nonex, stem, and the increased length of said lamp over that of the fiat heater plate. Further, due to the excessive amounts of heat conducted along the filament leads and through the relatively soft glass stem, the oxide bond between the lead and the glass press deteriorates and leaker failures result. The extremely high temperatures throughout the lamp, resultant of normal operation, cause internal strains in the graded seal and occasional leaker failures due to graded seal cracks.

Hence, it has been found advantageous, according to our invention, to provide a cooking lamp of all Vycor or all quartz construction, insofar as bulb and attendant stem and tubulation are concerned.

Vycor is the trade name for a good grade of Corning high silica glass, comprising approximately 96% silica, 3% boron oxide and the balance aluminum oxide, with impurities including traces of sodium oxide and arsenic oxide.

A filament mount comprising a Vycor stem and tubulation is sealed to the neck of the Vycor bulb. This stem has a fiared dish hermetically sealed about a partitioned tubin shrunken down onto the thin molybdenum-ribbon sections of the three-piece filament leading-in conductors, and a Vycor exhaust tubulation suitably affixed through the bottom side wall of the dish to allow evacuation of the lamp interior. During the sealing of this mount into the bulb neck, the application of less heat than in the conventional graded seal eliminates the vaporization of silica as smoke from the neck and dish and the condensation of said smoke on the nearest adjacent cooler portion of the interior wall of the bulb.

Due to increased heat carrying capacity of the ribbon type lead-in conductor, and to the lack of the conventional oxide bond between the conductors and conventional press, said bulb to dish seal may be made closer to the filament heat source and a shorter lamp results.

In its general aspect, the present invention has the object of overcoming the aforementioned disadvantages of the prior art graded seal cooking and heating lamps.

Specifically, an object of the present invention is the elimination of the large and expensive graded seal between the Vycor bulb and the relatively softer glass stem.

Another and specific object is the elimination of the relatively soft glass stem.

An additional object is the elimination of leakage paths through the stem due to overheating.

Another object is elimination of the strain and resultant cracks in the graded seal between the bulb neck and stem.

A further object is a cooking lamp of all Vycor construction which is suitable for sustained high temperature operation.

An additional object is an all Vycor cooking and heating of short overall length and reduced cost.

A still further object is the elimination of silica smoke condensation on the bulb interior.

Other objects and advantages of the invention will appear to those skilled in the art to which it appertains as the description proceeds, both by direct recitation thereof and by implication from the context.

Referring to the accompanying drawing, in which like numerals of reference indicate similar parts throughout the several views:

Fig. 1 is an elevational view of an all Vycor cooking lamp;

Fig. 2 is a sectional view of such a lamp;

Fig. 3 is a plan view of the lamp with the bulb broken away to show the filament;

Fig. 4 is a horizontal sectional view of the shrunken-down partitioned tubing on the line IV--IV of Fig. 2;

Fig. 5 is a horizontal sectional view of the partitioned tubing on the line IV-IV of Fig. 2, before leading-in conductors are sealed therem;

Fig. 6 is a side elevation of the all Vycor stem of the cooking lamp;

Fig. 7 is an elevational view of the filament leading-in conductor;

Fig. 8 is a view similar to Fig. 5, showing a partitioned tubing for use with three filament leading-in conductors;

Fig. 9 is a view similar to Fig. 5, showing a partitioned tubing for use with four filament leading-in conductors.

In the specific embodiment of the invention illustrated in the drawing, the reference numeral Iii designates a Vycor envelope or bulb in general of a cooking lamp. While Vycor has been selected for illustrative purposes, the invention is not to be understood as restricted to employment with Vycor, but may be used with other high melting point vitreous material such as quartz. The bulb comprises a domelike end portion H which curves outwardly for greater strength, a reflector portion l2 of general parabolic configuration, and a cylindrical neck portion l3 which extends downwardly below the reflector portion l2.

The inner surface of the portion I 2 iscoated with a reflector film I4 of an evaporated metal such as gold, silver or aluminum. The metal to be deposited on the reflector surface is juxtaposed within a suitable tungsten filament within the bulb and after .being vaporized in a protective-atmosphere by the filament heat, condenses on the surface. Gold, because of its relatively higher coeflicient of reflection of light energy of the infra-red wavelengths, is usually employed. During the metal evaporation process, the bulb H1 is in an inverted position. The end portion I l is masked by a lawyer of finely divided glass beads of desired depth and neck 13 is masked by a suitable closed end cylindrical shield.

For sealing within the bulb I 0, there is provided, as shown in Fig. 2, element mount 15. This mount [5 comprises a Vycor stem 16 on which are mounted and secured the filament support assembly l8 and filament l9.

Vycor stem I6, as shown in Fig. 6, consists of a flared dish 20, hermetically sealed to a coaxial partitioned tubing 2! and an appropriate exhaust tubulation 22. Within partitioned tubing 2| are, suitably in this showing, two three-piece leadin -in and supporting conductors 23. Each of these conductors 23, as shown in Fig. 7, consists of an inner refractory lead wire 24 suitably molybdenum, for joining to filament I 9, a thin non-oxidized moylbdenum ribbon 2,5 of rectangular cross section, approximately .0006" thick and A" wide, for sealing .into the partitioned tubing 2| and an outer molybdenum lead ribbon 25. approximately .005" thick and l/ wide, for positioning the conductors during sealing to tubing 21. At one end of ribbon 25, lead wire .24 is attached, as by spot welding thereto, while at the other end, ribbon .26 is formed into a loop and secured as by welding with the extremity of ribbon 25 therebetween.

To fabricate stem it, as shown particularly in Fig. 6, the loop formed by outer ribbon 26 of each conductor 23 is cut suitably in half to form a V diverging away from the axis of conductor 23. These conductors are inserted into the partitioned tubing 2| and held in the desired position in the tubing by the V shaped ribbons 2,6 which press against the partition and inner wall of the tubing. The end of tubing 2| nearest the extremity of inner wires 24 is closed off and the opposite end of tubing 2| evacuated by suitable means such as a pump (not shown) and tipped on as at 21. Heating tubing 2| to approximately its melting point along its length juxtaposed with respect to the moylbdenum ribbons 25, causes atmospheric pressure to collapse the .outer wall of the tubing onto the partition and hermetically seal and embed the ribbon therebetween. The uncollapsed ends of tubing 21 are cut off to the desired length exposing lead wires 24 and outer ribbons 26. To prevent arcing between the conductors 23, the partition is allowed to extend a suitable distance beyond the cut-oil outer wall on each end of tubing 2|, as shown in Fig. 2.

To complete Vycor stem I5, flared dish 20 having tubulation 22 affixed near the periphery of its bottom side wall, is sealed coaxially to the tubing 2! a suitable distance from the lower endof the shrunken portion of said tubing.

To form filament or element mount l5, inner lead wires 24 are first bent outward from axis of the stem 16, and then vertically upward parallel to the axis to receive filament support assembly I8. This assembly consists of reflector disc I! of slightly less diameter than the neck 13 of bulb Ill, and a plurality of refractory filament support wires 29 each having one end embedded in the arbor extension '30 on the underside of disc IT.

The supoprt Wires 29 extend radially outward along the undersuriace of disc I! and upward parallel to the stem axis through suitable slots arranged in equispaced circular sequence in the periphery of the disc.

Reflector disc I1 and arbor extension 30 are desirably made of Corning Multiform glass. Multiform is the trade name for powdered hard glass in a paraflin binder, molded by pressure to the desired form, and heated to remove the binder and to frit together the glass particles. The upper surface of disc I! is coated with an evaporated reflector film 3i, suitably the same as reflector film M of bulb It, to increase its reflection properties and reduce the heating of the stem [6.

Disc I! has twosuitable holes near its periphery through which inner lead wires 24 of conductors 23 pass. It is desirably aflixed to said lead wires by two pairs of flat-flanged refractorymetal eyelets 32 which are'attached, asby spot welding, to said wires and have their flanges respectively in flatwise engagement with the top and bottom surfaces of said disc.

It will be understood that at the points on the upper surface of reflector disc H where the filament support wires 29 project through the slots in the disc, and Where the flanges of the eyelets 32 grip the disc surface, the metallic reflector film 3| is removed, as by scraping, from a suitable area surrounding said points of contact to prevent electrical contact between supports 29 and eyelets 32 and resulting filament shorting.

In the usual manner, filament mount [5 is completed by mounting filament I!) on the extremities of inner lead wires 24 and support wires 29, as shown in Figs. 2 and 3. Filament l9, suitably a refractory metal such as tungsten, is a coiled sectional filament in a saw-tooth-like circular arrangement and having its two symmetrical sections in electrical parallel.

Filament mount I5 is sealed to the neck l3 of Vycor bulb Ill in the protective atmosphere of argon, flowing through tubulation 22 andinto the bulb interior, to protect the molybdenum parts "from oxidation. Less heat is applied for this seal as by welding, between the V-shaped sides of outer ribbons .28 of conductors 23.. One outer lead wire is connected, as by arc welding, to the shell of a suitable base 34 and the other lead wireis similarly connected to the center contact cf said base.

In some cooking, lamps a wider heating temperature ran e is desirable and an additional leading-in conductor 23 to the two section filament l 9 is provided so that the two'filament sections may be operated individually, or together in series, or in parallel at either 110 or 220 volts alternating current. When such a filament l9 requiring three leading-in conductors is em ployed, the tri-partitioned tubing 2W, as shown in Fig. 8, is employed in fabricating stem l6.

To. give still wider heating temperature range an auxiliary smaller concentric filament I9 (not shown) may be employed, thereby requiring a fourth leading-in conductor 23. In this case par-- titioned tubing 2|, as shown in Fig. 9, may be used for conducting the four conductors 23 through the envelope to the bulb interior.

Thus it will be seen from the foregoing description that our invention has overcome the disadvantages of the prior art graded seal cooking and heating lamps. Specifically, our invention has eliminated the large and expensive graded seal and the relatively softer glass stem. The attendant cracks in the graded seal and the creation of leakage paths through the stem due to overheating an oxide bond have been removed.

An all Vycor cooking lamp has been provided which is practical for sustained high temperature operation. The formation of silica smoke condensation on the bulb interior during the sealing of said lamps has been eliminated.

Although a preferred embodiment of our in vention has been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

We claim:

1. A high melting point vitreous cooking and heating lamp comprising: a high melting point vitreous envelope and an element mount; said envelope having a dome-like end portion, a reflector portion of general parabolic configuration having on its inner surface a, metal reflector film, and a cylindrical neck portion depending below said reflector portion; said element mount having a filament support assembly, a filament, and a high melting point vitreous stem; said stem comprising a flared high melting point vitreous dish of outside diameter to fit said neck, a coaxial high melting point vitreous partitioned tubing extending hermetically through said dish a suitable distance on the vacuum side of said stem, and a plurality of leading-in and supporting conduc tors for said filament, said conductors having non-oxidized metallic strips hermetically sealed and embedded in said tubing.

2. An all Vycor cooking and heating lamp comprising: a Vycor envelope and an element mount; said envelope having a dome-like end portion, a reflector portion of general parabolic configuration having on its inner surface a metal reflector film, and a cylindrical neck portion depending below said reflector portion; said element mount having a filament support assembly, a filament, and a Vycor stem; said stem comprising a flared Vycor dish of outside diameter to fit said neck, a coaxial Vycor partitioned tubing extending hermetically through said dish a suitable distance on the vacuum side of said stem, and a plurality of leading-in and supporting conductors for said filament, said conductors having non-oxidized metallic strips hermetically pending below said reflector portion; said element mount having a filament support assembly, a filament, and a quartz stem; said stem comprising a flared quartz dish of outside diameter to fit said neck and a coaxial quartz partitioned tubing extending hermetically through said dish a suitable distance on the vacuum side of said stem, and a plurality of leading-in and supporting conductors for said filament, said conductors having non-oxidized metallic strips hermetically sealed and embedded in said tubing.

4. A high melting point vitreous cooking and heating lamp comprising: a high melting point vitreous envelope and an element mount; said envelope having a dome-like end portion, a reflector portion of general parabolic configuration having on its inner surface a metal reflector film, and a cylindrical neck portion depending below said reflector portion; said elementmount having a filament support assembly, a filament, and a high melting point vitreous stem; said stem comprising a high melting point vitreous flared dish of outside diameter to fit said neck and a coaxial high melting point vitreous partitioned tubing extending hermetically through said dish a suitable distance on the vacuum side of said stem, and leading-in supporting conductors for said filament, said conductors having non-oxidized metallic strips hermetically sealed and embedded in said tubing; said filament support assembly comprising a Multiform reflector disc of slightly less diameter than said neck coaxially on said conductors and having on its upper surface a metal reflector film and on its lower surface an arbor extension, and a plurality of refractory metal filament supports; said supports each having one end embedded in said extension and the other end for supporting said filament.

5. An all Vycor cooking and heating lamp comprising: a Vycor envelope and an element mount; said envelope having a dome-like end portion, a reflector portion of general parabolic configuration having on its inner surface a metal reflector film, and a cylindrical neck portion depending below said reflector portion, said element mount having a filament support assembly, a filament, and a Vycor stem; said stem comprising a flared Vycor dish of outside diameter to fit said neck and a coaxial Vycor partitioned tube extending hermetically through said dish a suitable distance on the vacuum side of said stem, and a leading-in supporting conductor for said filament, said conductors having non-oxidized metallic strips hermetically sealed and embedded in said tube; said filament support assembly comprising a Multiform reflector disc of slightly less diameter than said neck coaxially on said conductors and having on its upper surface a metal reflector film and on its lower surface an arbor extension, and a plurality of refractory metal filament supports, said supports having one end embedded in said extension and the other end for supporting said filament.

6. An all quartz cooking and heating lamp comprising: a quartz envelope and an element mount; said envelope having a dome-like end portion, a reflector portion of general parabolic vcon'flgurati'on having on its inner surface a'rmetal reflector film, and a cylindrical neck portion depending'below said reflector portion; said'element sembly comprising a Multiform reflector disc of slightly less diameter than said neck coaxially on said conductors and having on its upper surface a metal reflector film and on its lower-Surface an arbor extension, and a plurality of refrac- 8 'tory metal filament supports, said supports having one end embedded in said extension andthe other end for supporting said filament.

AARON M. HAGEMAN. EDWARD A. JENKINS. HUGH D. FRASER.

REFERENCES CITED The following references are of record in the 10 file of this patent:

UNITED STATES PATENTS Number Name Date 2,088,544 Baselton July 27, 1937 15 2,115,839 Briefer May 3, 1938 2,144,521 Bergmans Jan. 17, 1939 2,363,531 Johnson Nov. 28, 1944

Images