US3346721A - Radiant heater with improved seal assembly - Google Patents

Description

Oct. 10, 1967 A. T. BASSETT, JR

RADIANT HEATER WITHIMPROVED SEAL ASSEMBLY 2 SheetsSheet 1 Filed Feb. 1, 1965 p \N \k Q? mm vv a mm mm mm I v "w w H T 0 m INVENTOR. Alf/Jar 7.' Basseff, JI: BY

His Afforney Oct. 10, 1967 BASSETT, JR 3,346,721

RADIANT HEATER WITH IMPROVED SEAL ASSEMBLY Filed Feb. 1, 1965 2 Sheets-Sheet 2 INVENTOR. Ar/hur 7. Basset! Jr.

His Attorney 3,346,721 RADIANT HEATER WITH IMPROVED SEAL ASSEMBLY Arthur T. Bassett, Jr., Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich,, a corporation of Delaware Filed Feb. 1, 1965, Ser. No. 429,304 1 Claim. (Cl. 219465) ABSTRACT OF THE DISCLOSURE In preferred form a surface heating unit including a solid cover plate and a lower support plate defining a low profile envelope about an infrared heating source including a seal across a peripheral separation between the cover plate and support plate comprising an annular resilient sealing element defining a primary barrier across the peripheral separation and a rigid sealing ring including a continuously formed rim thereon located interiorly of the envelope radially inwardly of the resilient seal to form a dammed space between the resilient seal and the interior of the envelope.

This invention relates to surface heating units and more particularly to surface heating units of the infrared type.

Present-day surface heating units are characterized, in the case of electrical units, by direct conductive heating of associated utensils. Such units typically include a utensil-supporting, spirally-wound sheathed tubular electrical resistance heating element or the like that has a substantial thermal lag before utensil heating occurs. Moreover, uneven contact between such surface heating units and utensils supported thereon can materially reduce the conductive heat transfer to the utensil. In order to reduce such thermal lag and to improve heat transfer to utensils, infrared surface heating units have been developed wherein a tungsten resistance element is utilized in association with a parabolic reflector to produce a unit having low thermal lag and good utensil heating characteristics. A representative unit of this type is disclosed in Patent No. 2,859,368, issued Nov. 4, 1958. While these units are suitable for their intended purpose, they must be evacuated to protect the tungsten filament. Furthermore, the whole unit has to be replaced when the filament burns out. Moreover, such units are relatively expensive as compared to presently used sheathed electrical resistance heating elements.

An object of the present invention is to improve infrared surface heating units by the provision of a low-profile unevacuated envelope including an upper plate of infrared transmissive material for supporting a utensil, a lower plate of low-thermal mass and a replaceable infrared emissive resistance element supportingly received within the envelope by removable support means for locating the element out of direct conductive heat transfer relationship with the surrounding envelope and wherein the interior of the envelope is sealed by improved means including an annular resilient member supported between the upper and lower plates at a peripheral separation therebetween and a rigid sealing ring located between the plates at their peripheral separation and including a rim portion thereon located radially inwardly of the periphery of the plates and extending upwardly to define a dammed space within the envelope for collecting leakage across the resilient sealing member.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

United States Patent I tively associated 3,346,721 Patented Oct. 10, 1967 ice.

In the drawings:

FIGURE 1 is a perspective view of a domestic electric range including surface heating units of the present invention;

FIGURE 2 is an enlarged view in vertical section taken along the line 22 of FIGURE 1;

FIGURE 3 is a view in horizontal section taken along the line 33 of FIGURE 2;

FIGURE 4 is a fragmentary elevational view of a portion of a resistance element support member of the present invention; and

FIGURE 5 is an enlarged fragmentary sectional view of area 5 in FIGURE 2.

Referring now to the drawings, in FIGURE 1 a domestic electric range 10 is illustrated having a plurality of surface heating units 12 in the top surface thereof operawith control means shown including selector knob portions 14 located on a rearward control panel 16 on the range 10.

Each of the surface heating units 12 are more particularly shown in FIGURES 2 through 4 as being located in an opening 18 formed in the upper surface 20 of the range 10 by a support ring 22 having its outer edge engaging the top surface 20 and a radially inwardly directed inner edge 24 forming a supporting seat for the outer peripheral edge of the unit 12. Each unit 12 has an outer envelope formed by a lower plate 26 located beneath an upper infrared transmissive utensil supporting plate 28 to form a space 29 therebetween. The upper plate 28 includes a peripheral edge 30 thereon joined to a peripheral edge 32 of the lower plate 26 by a clamping ring 34 directed continuously around the outer periphery of the unit 12 to be supportingly received by the edge 24 of ring 22. Joined to the upper surface of the edge 32 of lower plate 26 is a rigid continuous annular sealing member 36- having a radially inwardlylocated rim 38 thereof directed upwardly to form a space 40 continuously around the inner surface of the upper plate 28 adjacent the interface between the upper plate 28 and an annular sealing gasket 42 of a suitable resilient material on the outer edge of member 36. The gasket 42 is held in sealing engagement with plate 28 and member 36 by clamping ring 34 to thereby seal against leakage of utensil spillage or the like interiorly of the space 29. Any minor leakage across gasket 42 builds up in space 40 to create a back pressure that further improves the effectiveness of the sealed joint.

In accordance with certain principles of the present invention, a ribbon-shaped continuously spiraled infrared emissive electrical resistance coil 44 is disposed beneath the upper plate 28 out of direct heat transfer contact therewith throughout substantially all of the planar extent of the unit by a removable support structure 46 supportingly received by the lower support plate 26 which has a low-thermal mass.

The support structure 46 has a spider configuration including a centrally located hub portion 48 and a plurality of radially outwardly directed spokes 50 of a suitable electrically insulating material such as Vycor or other high temperature resistant ceramic material. Each of the spokes 50 extends radially outwardly from the central hub 48 to a point immediately adjacent the sealing member 36 and are supported above the lower plate 26 by a plurality of upwardly directed convolutions 52, 54 therein as best seen in FIGURE 2. In each of the spokes 50 is located a plurality of inclined grooves 56 that supportingly receive a portion of the continuous ribbon-like resistance element 44. Because of the inclination of the grooves 56, the resistance element 44 is located in planes inclined from the vertical whereby infrared energy emitted therefrom is directed upwardly through the upwardly utensil whereby substantially all of the emitted infrared energy is utilized for radiantly heating a supported utensil.

By virtue of the low thermal mass of the lower plate 26, and the isolation of the resistance element 44 from the lower plate 26 and the upper plate 28, the surface unit 12 has a relatively low thermal lag before effectively raising the temperature of an associated utensil. Moreover, because of the illustrated open configuration of the resistance element 44 with respect to the upper and lower plates 26, 28, efiectively all of the energy input to the resistance element 44 is used to raise the temperature of an associated utensil by radiant heating rather than direct conductive heat, as is presently the case in sheathed electrical resistance surface units By virtue of the support unit 46, a defective resistance element 44v can be easily replaced by merely removing the outer clamping ring 34 and disconnecting the ends of the resistance element from associated terminals and then removing the support unit 46 with the ribbon resistance 'element 44 thereon and replacing it with a new unit.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

In an infrared electrical surface heating unit, the combination of, an outer envelope having an upper infrared transmissive plate and a lower support plate, and means on said plates forming an open region therebetween, infrared heating means located Within said region, each of said upper and lower plates having a peripheral edge portion, a rigid sealing ring disposed between said edge portions continuously therearound including an inner rim spaced radially inwardly of said peripheral edge portions of said plates continuously around the periphery thereof forming a dammed spaced to contain foreign matter entering said region between said plates across said peripheral edge portions thereof, and a resilient annular sealing member disposed between said rigid ring and said upper plate, said resilient ring being held in sealing engagement between said upper plate and rigid seal ring by clamp means formed continuously around the outer surface of the upper and lower plates, said resilient annular sealing member forming a primary seal at the separation between the peripheral edges of said plates upstream of said dammed space defined by said rim on said rigid sealing ring.

References Cited UNITED STATES PATENTS 1,102,249 7/1914 Denhard 219-520 1,905,770 4/1933 Walker et a1 219467 2,179,934 11/1939 Jones 219-538 2,770,704 11/1956 Razlag 219345 2,799,765 7/1957 Jenkins et al. 219-464 X 2,870,316 1/1959 Ferguson 219464 X L. H. BENDER, Assistant Examiner.

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