US3892224A

US3892224A - Oven doors

Info

Publication number: US3892224A
Application number: US502366A
Authority: US
Inventors: Harold E Mckelvey
Original assignee: Shatterproof Glass Corp
Current assignee: Shatterproof Glass Corp
Priority date: 1974-09-03
Filing date: 1974-09-03
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01

Abstract

An oven door comprising front and back metal door panels having a central opening therein to provide a window for See-through into the oven compartment. A window unit is mounted in the window opening and comprises inner and outer transparent glass panels, with the inner panel being adjacent the oven and the outer panel exposed to the ambient atmosphere. The outer surface of the outer glass panel is provided with a siliceous or frit material in the form of a plurality of spaced, parallel stripes or bands, with open spaces therebetween forming unobstructed viewing areas through which the interior of the oven can be readily observed. The siliceous or frit material preferably comprises innumerable small glass particles adhered to the glass panel by layers of a ceramic paint and which present a myriad of exposed minute surfaces which radiate heat emanating from the oven to the surrounding atmosphere.

Description

O United States Patent 1 McKelvey 1 OVEN DOORS [75] Inventor: Harold E. McKelvey, Plymouth,

Mich.

[73} Assignee: Shatterproof Glass Corporation, Detroit, Mich.

[221 Filed: Sept. 3, 1974 [21] Appl. No.: 502,366

[52] US. Cl. 126/200; 52/306; 52/616; 165/133 [51 Int. Cl. F23m 7/00 [58] Field of Search 126/190, 200; 350/299, 350/288; 117/40, 43, 124 A, 94, 97, 129; 165/133; 52/306, 202, 616

[56] References Cited UNITED STATES PATENTS 2,531,945 11/1950 Moulton 117/124 A 2,810,660 10/1957 Carpenter 117/124 A 3,088,453 5/1963 Grahn et a1 126/200 3,192,575 6/1965 Rosenau, Jr. et al. 126/200 Primary Examiner-Carroll B. Dority, Jr. Assistant Examiner-Larry 1. Schwartz Attorney, Agent, or FirmWil1iarn E. Nobbe 5 7] ABSTRACT An oven door comprising front and back metal door panels having a central opening therein to provide a window for See-through into the oven compartment. A window unit is mounted in the window opening and comprises inner and outer transparent glass panels, with the inner panel being adjacent the oven and the outer panel exposed to the ambient atmosphere. The outer surface of the outer glass panel is provided with a siliceous or frit material in the form of a plurality of spaced, parallel stripes or bands, with open spaces therebetween forming unobstructed viewing areas through which the interior of the oven can be readily observed. The siliceous or frit material preferably comprises innumerable small glass particles adhered to the glass panel by layers of a ceramic paint and which present a myriad of exposed minute surfaces which radiate heat emanating from the oven to the surrounding atmosphere.

11 Claims, 9 Drawing Figures OVEN DOORS BACKGROUND OF THE INVENTION This invention relates to an oven door of the type incorporating a window means for viewing the oven interior when the door is closed to observe the advance of the cooking process.

In the past, it has been common practice to provide a unitary double-glazed glass panel for a windowed oven door with a substantially dead air space between the two panels. Although double-glazed oven doors of this character were designed to prevent transmission of oven heat, they did not function satisfactorily to maintain the outer exposed glass panel at the desired low temperature, particularly after the oven had been on for some period of time. To overcome this objection, a thin, transparent reflective metal coating has been applied to the inner surface of the outer glass panel to reduce the transmission of oven heat through the window. While these coatings have materially reduced the problem of excessive window temperature, they have not proven entirely successful in meeting the increasingly stringent standards required of the industry for lower window temperatures.

Significant improvement in this area has been attained by the present invention, which contemplates a novel and improved double-glazed window unit which effectively reduces the temperature of the outer glass panel, as well as the exterior surface of the metal door, by producing a more rapid and efficient radiation or dispersion of the oven heat to the surrounding atmosphere.

In carrying out the invention, there is adhered to the outer surface of the outer window glass panel a plurality of spaced, parallel stripes or hands of a siliceous or frit material, with the open spaces therebetween providing unobstructed viewingareas through which the interior of the oven can be readily observed. The siliceous or frit material preferably comprises innumerable small glass particles which present a myriad of exposed minute surfaces that collectively provide a large radiating surface from which a maximum amount of heat emanating from the oven will be dispersed to the surrounding atmosphere. The air currents within the room, flowing or wiping across the heat radiating stripes or bands will act to accelerate dissipation of the oven heat and thereby reduce the temperature of the outer glass panel to, and maintain it, within acceptable limits.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an oven employing a door constructed in accordance with the invention;

FIG. 2 is a vertical transverse section of the doubleglazed window unit of. the invention mounted in the oven door;

FIG. 3 is a plan view of the outer glass panel showing a plurality of spaced horizontal stripes or bands of a ceramic paint applied thereto;

FIG. 4 is a similar view showing the heat radiating particles applied to the ceramic paint;

FIG. 5 is an enlarged sectional view of the outer glass panel taken substantially on line 55 of FIG. 4;

FIGS. 6 and 7 are plan views of the outer glass panel showing alternate arrangements of the heat radiating stripes or bands, and

FIGS. 8 and 9 are perspective views of the oven door showing two ways in which the heat radiating particles of the invention may also be applied to the front metal door panel in combination with the window unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is illustrated a floor standing range 10 employing an oven door 11 constructed in accordance with the present invention. The oven door 11 includes front and back

metal door panels

12 and 13 which are provided with substantially rectangular aligned openings therein defined by inwardly turned flanges l4 and 15 respectively and adapted to receive therein the novel window unit 16 of this invention. The window unit 16 comprises inner and outer transparent,

tempered glass panels

17 and 18 mounted in spaced, parallel relation in a metal frame 19.

In order for an oven range to be acceptable for domestic use, it is required that the outer surface of the outer glass panel not exceed a specified temperature, the purpose being, of course, to prevent-persons and especially children, from being burned should they accidentally come in contact with the panel. The requirements as to maximum permissible temperature are becoming increasingly stringent, presenting a serious problem for the range manufacturer. The latest requirement of Underwriters Laboratories for maximum accaptable surface temperature of the outer glass panel is 172F based on an ambient temperature of 77F.

It is the primary purpose of this invention to effect reduction of the temperature of the outer glass panel to an acceptable degree during normal operation of the oven. This is achieved by the provision of means applied to the outer surface of the glass panel for causing the heat from the oven to be rapidly radiated or dispersed into the ambient atmosphere. This dissipation of heat will also be accelerated by the ambient air currents as they wipe or flow across the glass panel.

In practicing the invention, there is first applied to the outer surface of the glass panel 18 a plurality of narrow stripes or hands 20 (FIG. 3) of a ceramic paint. While the paint is still wet, innumerable small particles 21 of a glassy siliceous material are sprinkled, or otherwise deposited, on the painted stripes in sufficient quantity to form a layer of the desired density and thickness. The particles 21 preferably consist of irregular crushed glass chips or small glass beads. While some of the-glass particles will become embedded in the painted layers others will project thereabove to form protrusions which coalesce or blend together to provide a large number of minute exposed surfaces which combine to receiveoven heat and radiate it to the surrounding atmosphere. Significant improvement has been experienced with this arrangement in the transfer of oven heat to the ambient atmosphere, thereby maintaining the glass panel at a lower temperature than has heretofore been obtained.

It is preferred that the heat radiating stripes or bands be about one sixteenth inch wide and the open spaces between them from three thirty-seconds to one eighth inch wide, although these relative widths can, of

course, be varied as desired. However, it has been found that these relative widths of stripes and open spaces results in excellent heat transfer, while, at the same time, affording adequate viewing of the interior of the oven.

After the glass particles 21 have been applied to the layers of ceramic paint, the panel is placed in an oven or furnace and heated to a temperature in the neighborhood of 1250F. The panel is then removed and subjected to blasts of cold air to effect the tempering of the glass panel in a manner well known in the art. During heating of the panel, the layers of ceramic paint will be fused to the glass and the glass particles simultaneously bonded to the paint. After the panel has been tempered, the excess loose particles of glass can be readily removed by simply shaking the panel. The composition of the glass particles is matched with that of the glass panel so that the coefficient of expansion will be the same, or sufficiently close, to avoid the likelihood of breakage.

While different types of ceramic paint may be used, paint obtained from the Ferro Corporation, Pittsburgh, Pa. under N0. M-3ll5 Black and No. M-0133 White, both in 30K oil, has been found satisfactory. The ceramic paint is preferably applied to the glass panel by the silk screen technique, using a squeegee. Although the thickness of the painted layers may vary according to different requirements, a thickness in the range of 0.002 to 0.005 inch and preferably 0.003 inch has been found satisfactory. While black paint may be desired in certain cases, white paint is cooler and will, ordinarily, prove more effective.

As set forth above, the glass particles 21 preferably consist of small glass bends or finely crushed glass chips, sometimes referred to as fine ice. The glass beads may be obtained from the Fisher Scientific Co., Pittsburgh, Pa. They are preferably white and may vary in size, by way of example, from 0.006 to 0.010, and preferably 0.008 inch.

The crushed glass chips or fine ice are available from Hercules Incorporated, Washington, Pa. under the name Drakenfeld No. 2482. These small, irregular glass particles may be of substantially the same size as the glass beads.

The thickness of the combined layers of ceramic paint and glass particles may also be varied but a thickness of between 0.010 and 0.020 inch has proven satisfactory, with the optimum thickness being about 0.015 inch. The thicker the layer of glass particles, the greater the radiation of heat therefrom. However, the heavier the glass layer, the rougher the surface thereof which makes it somewhat harder to clean. In this connection, it has been found that the fine ice particles tend to fuse during heating of the glass panel to a greater degree than the glass beads which results in a smoother surface having a more pleasing appearance and texture.

While the use of glass particles is preferred, sand or metal filings may also be employed. It has been further found that upon firing of the ceramic paint before it dries, there is a tendency for the wet paint to bubble, with some of the bubbles breaking and others not, which results in a roughened heat radiating surface.

Although in FIG. 4, the heat radiating stripes 21 are horizontally disposed, they may be used in different arrangements. For example, they may be vertically disposed as in FIG. 6 or arranged in checker-board fashion as in FIG. 7. Other designs or patterns may also be employed.

It has also been found that, on occasion, the temperature of the front metal panel 12 of the oven door, usually along the upper portion thereof, may exceed the permissible maximum temperature for this part of the door. Therefore, the present invention also contemplates applying the heat radiating stripes described above to this area of the front panel, as indicated at 22 in FIG. 8. Or, if desired, the upper portion of the door panel, above the window, may be completely covered with the heat radiating particles as indicated by the numeral 23 in FIG. 9. In these embodiments, the ceramic paint is first applied to the outer surface of the front door panel 12 and the glass or other particles then sprinkled thereon, after which the panel is placed in a furnace and heated to the desired temperature to fuse the ceramic paint thereto and bond the heat radiating particles to the paint.

It is to be understood that the present disclosure has been only by way of example and that many additional modifications, changes, and various details may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

I claim:

1. An oven door comprising a main body portion having a substantially rectangular opening therein, a window unit mounted in said opening and comprising inner and outer transparent glass panels, with the inner panel being adjacent the oven and the outer panel exposed to the atmosphere, a plurality of spaced stripes formed of innumerable heat radiating particles adhered to the other surface of the outer glass panel, with the spaces therebetween forming unobstructed viewing areas through which the interior of the oven can be observed, said particles presenting a myriad of exposed minute surfaces which radiate heat emanating from the oven to the surrounding atmosphere to thereby reduce the temperature of the outer glass panel.

2. An oven door as claimed in claim 1, in which the heat radiating particles comprise a siliceous material.

3. An oven door as claimed in claim 1, in which the heat radiating particles comprise irregular glass chips.

4. An oven door as claimed in claim 1, in which the heat radiating particles comprise glass beads.

5. An oven door comprising a main body portion having a substantially rectangular opening therein, a window unit mounted in said opening and comprising inner and outer glass panels, with the inner panel being adjacent the oven and the outer panel exposed to the atmosphere, a plurality of spaced layers of a ceramic paint adhered to the outer surface of the outer glass panel, with the spaces therebetween forming unobstructed viewing areas through which the interior of the oven can be observed, heat radiating particles adhered to the layers of ceramic paint and presenting a myriad of exposed minute surfaces which radiate heat emanating from the oven to the surrounding atmosphere to thereby reduce the temperature of the outer glass panel.

6. An oven door as claimed in claim 5, in which the heat radiating particles comprise a siliceous material.

7. An oven door as claimed in claim 5, in which the heat radiating particles comprise irregular glass chips.

8. An oven door as claimed in claim 5, in which the heat radiating particles comprise glass beads.

9. An oven door as claimed in claim 1, in which the main body portion of the door includes front and back door panels in which the window unit is mounted, and in which a portion of the outer surface of the front door panel above the window unit is provided with heat radiating particles adhered thereto.

10. An oven door as claimed in claim 9, in which the heat radiating particles consist of a glassy siliceous material.

11. An oven door as claimed in claim 5, in which the main body portion of the door includes front and back 5 theretodoor panels in which the window unit is mounted, and

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENTNO. 3,892,221,, a a DATED .July 1, 1975 lNV ENTOR(S) Harold E. McKelvey' It is certified that error appears in the above-identified patent and that said Letters'Paterit are hereby corrected as shown below: ,t v

Column 3, 'lirie 29, cancel "bends" and insert -beadsv v Claim 1, line 8, cancel "other" and substitute -outer I I v Signed and Scalecl'this twenty-fifth of November 1975 I [SEAL] a a f Attest.

RUTH c. MASON Arresting Ofi'icer UNITED sT TEs PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,892,221,

DATED July 1, 1975 lN\/ ENTOR(S) Harold E. McKelvey' It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 29, cancel "bends" and insert -beads- Claim 1, line 8, cancel "other" and substitute -outer- Signed and Scaled this twenty-fifth Day Of November 1975 [SEALl A ttest:

RUTH c. MASON Arresting Officer C. MARSHALL DANN (ummissimn'r ufPalems and Trademarks

Claims

11. An oven door as claimed in claim 5, in which the main body portion of the door includes front and back door panels in which the window unit is mounted, and in which a portion of the outer surface of the front door panel above the window unit is provided with heat radiating particles of a glassy siliceous material adhered thereto.