US3275874A

US3275874A - Electrically energized heat radiator

Info

Publication number: US3275874A
Application number: US193940A
Authority: US
Inventors: Jennings Jo Emmett
Original assignee: Jennings Radio Manufacturing Corp
Current assignee: Jennings Radio Manufacturing Corp
Priority date: 1962-05-11
Filing date: 1962-05-11
Publication date: 1966-09-27
Anticipated expiration: 1983-09-27

Description

p 27, 1965 J. E. JENNINGS ELECTRICALLY ENERGIZED HEAT RADIATOR 2 Sheets-Sheet 1 Filed May 11, 1962 INVENTOR J0 EMME T JENNINGS ATTORNEY p 27, 1966 J. E. JENNINGS ELECTRICALLY ENERGIZED HEAT RADIATOR Filed May 11, 1962 2 Sheets-Sheet 2 m mm V I. mN m J n W E m ATTORNEY United States Patent,

ELECTRICALLY ENERGIZED HEAT RADIATOR .lo Emmett Jennings, San Jose, Calif., assignor to Jennings Radio Manufacturing Corporation, San Jose,

Calif., a corporation of Delaware Filed May 11, 1962, Ser. No. 193,940 7 Claims. '(Cl. 313-183) This invention relates to improvements in electrically energize-d heat radiators of the enclosed and sealed tube type.

Electrically energized heat radiators are made in various types .such as the open Nichrome resistance heaters which have the lowest efficiency. Other various types have improved efficiencies.

As the temperature of the heating element is increased, the efficiency is also increased. The maximum efiiciency of B.t.u.s output for a given wattage input takes place up to about 180*02000 F. for the heating element where the efiiciency levels off at a plateau. To make eflicient use of this heat it is necessary to provide a structural arrangement wherein there is a very high radiant energy dissipation factor and means are provided to maintain a heating element which will not oxidize or destroy itself.

An object of my invention is to provide a highly efficient electrically energized heat radiator for both enclosed or open areas which is at the same. time economical to produce and has a long operating life.

Another object of my invention is to provide an electrically energized heat radiator which has an enclosed housing of sheet metal with a heating element enclosed by reflector means within the housing to focus theheat given off to a radiating portion of the housing.

A further object of the invention is to provide an electrically energized heat radiator using a sheet metal housing thus eliminating-the need for filters to prevent the emanation of visual rays.

A still further object of the invention is to provide an electrically energized heat radiator that utilizes a housing within which is mounted the heater element and wherein the housing may be evacuated for use or wherein a suitable gas may be introduced to inhibit evaporationand increase the 'life of the structure, and at the same time, in case of use of a gas, the amount of gas used can be controlled so that the inside pressure will be about equal to .atmospheric pressure at operating temperature.

A yet further object of the invention is to provide such a heater that can be operated in all attitudes.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples are given by way of illustration only and, while indicating preferred embodiments of the invention, are not given by way of limitation, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

For a more complete understanding of the nature and scope of the invention reference may be had to the drawings, in which FIG. '1 is a partially sectioned elevational view of the heater according to my invention;

FIG. 2 is a sectional view along line 22 of FIG. 1;

FIG. 3 is a partially sectioned elevational view of a modified form of the heat radiator; and

FIG. 4 is an end view at the left of FIG. 3.

Throughout the description like reference. numbers refer to similar parts.

There is shown in FIGURES 1 and 2 a bulb type of form that the heat radiator may take. The heat radiator 3,275, 74 Patented Sept. 27, 1966 is generally indicated at .10. A piece of Nichrome sheet of relatively thin thickness is drawn into the shape of a bulb or housing portion 11 of generally conoid-al shape 1'1a at one end and having a cylindrical configuration of smaller diameter at the other or neck end 11b. The neck end lllb is thinned down at 11a to receive the seal and support generally indicated at I12 for the filaments and their support. This seal 12 is of dielectric material and shown in FIG. 1 as glass. A heat resistant and reflective inside coating .13 of chrome, for example, is provided on the conical portion 111; and the other end of 11a is open to receive a heat radiating end closure to be described. Other non-oxidizing metals may be used for the housing such as nickel or other non-oxidizing alloys.

A filament 14 is bent into a suitable shape such as the maximum heat radiating portion 14a of a z-ig-zag shape, for example, and provided with leads 1% and 14c which are bent in an angle to converge toward each other and then project in parallel spaced relationship about midway the length of the housing toward and through the neck illb where they pass through and are supported in part by the seal 12. The high temperature filament may be of a suitable metal such as molybdenum, tantalum, tungsten, rhenium and columbian and the like. Although tungsten is widely known, readily available, and very practical, it has one disadvantage for this type of application. The inrush currents are extremely high as compared with the current at operating temperature. This means that the inrush currents will start high and level off. The other materials indicated for the filament are not as radical in their changes from hot to cold as far as resistance is concerned. Therefore the inrush currents for these other materials would be far lower in comparison. In any case, any one of those metals referred to can be used and will perform excellently.

A ceramic insulator or support 15 is formed with spaced apart slots 15a therein to receive and support the zig-zag runs of the maximum heating portion 144: of the filament. Suitable further. interpositioned slots 15b of relatively larger size assist in ventilation and dissipation of the heat. A support for the insulator 15 is provided by a rod 16 which is embedded at 16a in the ceramic support 15 and then passes downwardly .as seen in FIG. 1 through a ceramic insulator and spacer -17 through which also pass the leads '14b and 140 of the filament in parallel spaced relation on opposite sides of the support rod v16.

A reflector 18 of dish-like shape of suitable metal such as the nichrome material making up the housing 11 is mounted at its apertured center 18a on an annular shoulder or ledge 17a of the insulator 17. The reflector may have a highly polished surface or be provided with a chrome face 18b so as to better reflect and focus the heat toward the heat radiating end of the radiator.

In assembly of this bulb shaped or conical shaped housing, the filament 14 and the support rod 1 6 and support 15 can be assembled and positioned through the large open end of the housing 11, with a portion of the seal 12 previously assembled to the rod 16 and leads 14b and 140 :and then the seal can :be joined at its annular periphery 12a to the thinned annular portion on the neck 11b.

Following this assembly of filament into housing and sealing at the neck end support, the filament can be readily production tested and then the heat radiating end 19 of convex shape is placed on the open end of the conical portion 11a of the housing 11 and joined thereto by an annular heliarc weld at 19a. This heat radiating end 19 is of like relatively thin cross section nichrome sheet material .as is the housing 11. This relatively thin membrane serves to readily conduct the heat therethrough and radiate it therefrom but serves as a barrier for possible harmful radiation from the maximum heat radiating portion 14a'of the filament. Thus, filterswhich would impede the heat radiation and decrease the overall efiiciency are unnecessary. The end closure or heat radiating surface 19- should be black if possible, and not shiny as the later would decrease the radiating efliciency.

The maximum heat radiating portion 14a of the elec trode should be reasonably close to the heat radiating end closure 19 f the housing 11 so that large amounts of radiant energy will be absorbed by this metal membrane. Due to the relatively thin cross section of this membrane 19, it will radiate the energy into the free space outside thereof. Much of the energy reflected back toward the filament portion 14a from the radiator end 19 will be reflected back toward the radiator end 19 by the reflector 18 and if there is a reflective coating or surface 13 on housing 11 it will function to reflect the heat and increase the efficiency. This action of reflecting the heat will stop the heatfrom being dissipated in the cool end. 7

The housing 11 after implacement of the heat radiating end 19 can be evacuated as through the tip-off portion 12b of the seal 12 if the heat radiator is to be used in an evacuated condition. i I

The housing 11 can equally as well be provided with an inert gas through the tip-off portion 12b or otherwise. The amount of the inert gas or the like may be that amount that will at operating temperature provide an atmosphere of pressure or that average atmospheric pressure at which the heater is to be operated. Small quantities of hydrogen or inert gas may be used. Helium or argon or nitrogen could not be used. By such use of an appropriate gas the evaporation of the elements within the heater is greatly reduced and the life of the heating element will be enhanced. The use of a gas also has the additional advantage that the bulb would be at a very good vacuum when cold, since the filament would be operating when hot at atmospheric pressure or that average pressure provided for. The gas also serves as a convection medium for transferring heat and further carries away the heat to the cold surface as another way of increasing the efliciency. Since the filament can be operated in a range of about 1800 to 2000 F., it will be operating at its most eflicient rating point.

, While a glass seal 12 has been indicated at the neck or stem 11b other suitable dielectric material may be used.

Nichrome has been indicated as a metal for the housing and radiating end, however, other metals could be sub-' stituted such as nickel or other non-oxidizing alloys.

This heat radiator can be used in any attitude and does not have to be operated froman overhead as do some other bulb type heat radiators of the electrically ener-. gized type.

While a tubulation is shown at the tip-off portion 1215, it is possible to produce this heat radiator simply by sealing in an atmosphere of a controlled gas pressure which would eliminate one or more operations andv thereby reduce total cost of manufacture.

The structure illustrated in FIG. 1 provides at the neck end 11b a mounting member generally indicated at 20 which may include an insulating cylindrical sleeve 21 which has a non'conductive base 22 molded around plug-in leads 23 protruding therethrou-gh and connected internally such as by screws 24 to the ends of filament leads 14b and 140 that protrude through the seal 12 and extend within the surrounding radially outwardly spaced sleeve 21. The upper end of sleeve 21 is attached to the internal neck portion 11b by-an annular sleeve 25. A fin type of suitable heat radiator or dissipating means 26 may be mounted about the neck portion 11b and attached to the upper end of the annular collar 21 as by a set screw 26a.

A modified form of the heat radiator 28 is shown in FIGURES 3 and 4. The heat radiator may be made in cylindrical shape and such a radiator would have similar rearranged and shaped parts. It has a cylindrically shaped housing 29 and a dielectric plug end 30 through which extends the ends of the filament 31. A suitable support strut or rod 32 is embedded in the plug end 30 and extends within the housing between the parallel spaced apart leads of the filament. The filament may be of U-shape in its projection within the housing or suitably shaped to provide suflicient heating length.

A ceramic high heat resistant support 33 extends transversely at the end of the support rod 32 to which it is affixed for support. The plug end 30 may have a protruding annular rim portion 30a, see FIG. 4, which is metalized and brazed to the surrounding annular end of housing 29 as at 34.

The'other end 35 may be of glass and bonded to the cylidrical housing 29 and provided-witha tip-off 35a. Other forms of the cylindrical type could be provided such as with the filament leads leaving from opposite ends. This type of cylindrical 'heat radiator as disclosed in FIGURES 3 and 4 may be used as a tubular radiator for industrial application. Y

I have herein provided electrically energized heat radiators that are economical to manufacture. At the same time a highly efficient radiator is provided which adapts itself to many. uses such as inenclosed and free spaces. Due to the flexibility of the designs, either plug-in or wired-in connections may be made giving the system a preponderance of diversified uses and applications either forheating'or industrial applications such as drying, dehydration, baking, cooking and many other uses.

I claim as my invention:

1. An electricallyv energized heat radiator comprising in combination, an" enclosed hermetically sealed housing of nonoxidizing relatively thin metallic material including a radiating end portion forming part of the hermetically sealed housing, a filament spaced within the housingin substantial parallelism with said radiating end portion, dielectric means connected with the wall of the housing on the end thereof opposite said radiating end portion to support said filament and lead-in connections to the filament from outside to within the housing, and a heat reflector apart from the interior surface'of said housing and disposed within said housing on the side of said maximum heat radiating portion of the filament opposite said heat concentrating end wall portion of the housing to focus the heat on said maximum heat radiating wall portion.

2. An electrically energized heat radiator comprising in combination, an enclosed housing bulb of nonoxidizing relatively thin metallic sheet material having a neck openig at one end and a curved heat radiating portion at the other end, a filament spaced within the housing with its maximum heat radiating portion in closely spaced parallel relation to said heat radiating end portion, dielectric support means supporting the filament and hermetically connected to the neck end of said housing where the ends of the filament pass to the outside of the housing, and a metallic heat reflector means disposed within said housing on the side of said maximum heat radiating portion of the filament opposite said heat radiating end portion of the housing to focus the heat on said heat radiating end portion of the housing.

.3. An electrically energized heat radiator comprising in combination, an enclosed housing bulb of nonoxidizing relatively thinmetalli'c sheet material having a neck opening at one end and a curved heat radiating portion at the other end, a filament spaced within the housing with its maximumhe'at radiating'portion in closely spaced parallel relation to said heat radiating end portion, dielectric sup port means supporting the filament and hermetically connected to th'e neck end of said housing where the ends of the filament pass to the outsideof the housing, a further support means extending within said housing' from the dielectric means at theneck end and further supporting said filament, said further support means including a dielectric member extending transversely across thehousing and having grooves therein to contain the maximum heat radiating portion of the filament, a heat reflector of disc-like shape mounted on said further support means within the housing in spaced relation from the maximum heat radiating portion of the filament to focus the heat on said heat radiating end portion of the housing, the inner surface of the wall of said housing adjacent said filament except for the heat radiating end thereof having a heat resistance and reflective coating thereon, and mounting means for the disc-like heat reflector at the neck end thereof.

4. An electrical energized heat radiator according to claim 3 wherein said housing is filled with a gas to inhibit evaporation of said electrode and conduct heat away therefrom to increase the efficiency, said gas being of a quanity that expands to about one atmosphere of pressure when said radiator is operating at maximum.

5. An electrically energized heat radiator according to claim 2 including a further support means extending within said housing from the dielectric means at the neck end and supporting the maximum heat radiating portion of the filament, and wherein said heat reflector means comprising a concave metallic member is supported by said further support means in spaced position adjacent said maximum heat radiating portion of the filament.

6. An electrically energized heat radiator according to claim 3 wherein said housing is evacuated.

7. An electrically energized heat radiator according to claim 3 wherein said housing bulb is of generally conical shape intermediate the neck end and the heat radiating end portion and said heat radiating end portion is a separate portion welded to the adjacent conical-like portion.

References Cited by the Examiner DAVID J. GALVIN, Primary Examiner.

GEORGE WESTBY, Examiner.

5 D. E. SRAGOW, C. R. CAMPBELL, Assistant Examiners.

Claims

1. AN ELECTRICALLY ENERGIZED HEAT RADIATOR COMPRISING IN COMBINATION, AN ENCLOSED HERMETICALLY SEALED HOUSING OF NONOXIDIZING RELATIVELY THIN METALLIC MATERIAL INCLUDING A RADIATING END PORTION FORMING PART OF THE HERMETICALLY SEALED HOUSING, A FILAMENT SPACED WITHIN THE HOUSING IN SUBSTANTIAL PARALLELISM WITH SAID RADIATING END PORTION, DIELECTRIC MEANS CONNECTED WITH THE WALL OF THE HOUSING ON THE END THEREOF OPPOSITE SAID RADIATING END PORTION TO SUPPORT SAID FILAMENT AND LEAD-IN CONNECTIONS TO THE FILAMENT FROM OUTSIDE TO WITHIN THE HOUSING, AND A HEAT REFLECTOR APART FROM THE INTERIOR SURFACE OF SAID HOUSING AND DISPOSED WITHIN SAID HOUSING ON THE SIDE OF SAID MAXIMUM HEAT RADIATING PORTION OF THE FILAMENT OPPOSITE SAID HEAT CONCENTRATING END WALL PORTION OF THE HOUSING TO FOCUS THE HEAT ON SAID MAXIMUM HEAT RADIATING WALL PORTION.