U.S. patent application number 11/682451 was filed with the patent office on 2007-09-27 for interchangeable glass ceramic tops for a cooking stove.
Invention is credited to Sascha Backes, Torsten Gabelmann, Ioannis Kosmas, Wolfgang Schmidbauer, Martin Taplan.
Application Number | 20070221654 11/682451 |
Document ID | / |
Family ID | 38006419 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070221654 |
Kind Code |
A1 |
Taplan; Martin ; et
al. |
September 27, 2007 |
INTERCHANGEABLE GLASS CERAMIC TOPS FOR A COOKING STOVE
Abstract
The cooking stove top can be equipped with two different glass
ceramic tops with different IR transmission spectra, which each
have at least one cooking area, which is heated by a radiant
heating body cooperating with a temperature-limiting adjusting
device, which limits a surface temperature of the glass ceramic top
installed in the cooking stove and/or the surroundings. To
economically, variably, and individually adjust the IR transmission
of one glass ceramic top with a higher IR transmittance to that of
a lower IR transmittance of another glass ceramic top so that they
are interchangeable, the glass ceramic top with the higher IR
transmittance is provided with an absorbing and/or reflecting
coating. When the glass ceramic tops are interchangeable, either
can be used in a given cooking stove without changing an expensive
temperature-limiting device that is designed for the cooking
stove.
Inventors: |
Taplan; Martin;
(Rheinboellen, DE) ; Kosmas; Ioannis;
(Stadecken-Elsheim, DE) ; Schmidbauer; Wolfgang;
(Mainz, DE) ; Gabelmann; Torsten; (Weisbaden,
DE) ; Backes; Sascha; (Ruedesheim, DE) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
38006419 |
Appl. No.: |
11/682451 |
Filed: |
March 6, 2007 |
Current U.S.
Class: |
219/452.11 |
Current CPC
Class: |
H05B 3/74 20130101; H05B
2213/07 20130101; H05B 3/746 20130101; Y10T 428/24926 20150115 |
Class at
Publication: |
219/452.11 |
International
Class: |
H05B 3/68 20060101
H05B003/68 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2006 |
DE |
10 2006 011 315.2 |
Claims
1. A stove top for a cooking stove, wherein said cooking stove
comprises either a first glass ceramic top with a higher IR
spectral transmittance or a second glass ceramic top with a lower
IR spectral transmittance, which each have at least one cooking
area thereon; a respective radiant heating body arranged below said
at least one cooking area; and a temperature-limiting adjusting
device cooperating with said respective radiant heating body, which
limits a surface temperature of the glass ceramic top installed in
the cooking stove to a maximum value; wherein said first glass
ceramic top with said higher IR spectral transmittance is provided
with means for absorbing or reflecting infrared radiation in order
to change said higher IR spectral transmittance so as to be the
same or substantially the same as that of said second glass ceramic
top with said lower IR spectral transmittance, so that the
temperature-limiting adjusting device for the radiant heating body
may be retained in the cooking stove without any changes if said
first glass ceramic top replaces said second glass ceramic top or
is installed in said cooking stove instead of said second glass
ceramic top.
2. The cooking stove top as defined in claim 1, wherein said means
of absorbing or reflecting infrared radiation is an IR-absorbing
coating or an IR-reflecting coating provided on said first glass
ceramic top.
3. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating extends over an entire
surface of said first glass ceramic top.
4. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating has a structured pattern or
is in the form of a structured grid.
5. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating is provided on a topside side
and/or a bottom side of said first glass ceramic top.
6. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating is applied to the first glass
ceramic part by screen-printing.
7. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating comprises enamel.
8. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating comprises a lustrous paint
and said lustrous paint has gold, and/or platinum, and/or palladium
components.
9. The stove top as defined in claim 2, wherein said IR-absorbing
coating or said IR-reflecting coating comprises a SnO.sub.2 coating
and is provided on a bottom side of the first glass ceramic
part.
10. The stove top as defined in claim 9, wherein said SnO.sub.2
coating has a predetermined thickness that causes an adjustment of
said IR transmittance of said first glass ceramic top to that of
said second glass ceramic top having said lower IR spectral
transmission.
11. The stove top as defined in claim 9, wherein said first glass
ceramic top has at least one IR-reflecting roughened surface region
on an underside thereof.
Description
CROSS-REFERENCE
[0001] The invention described and claimed hereinbelow is also
described in German Patent Application DE 10 2006 011 315.2-54,
filed Mar. 11, 2006, in Germany. The subject matter of the
aforementioned German Patent Application is explicitly incorporated
herein by reference and this German Patent Application provides the
basis for a claim of priority for the invention described and
claimed hereinbelow under 35 U.S.C. 119.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] The present invention relates to a cooking stove top, which
can be equipped with at least two different glass ceramic tops with
different IR spectral transmittance (type A, type B), which each
have at least one cooking area, which is heated from below by means
of a radiant heating body cooperating with a temperature-limiting
adjusting device, which limits the surface temperature of the stove
top installed in the cooking stove to a maximum value.
[0004] 2. Related Art
[0005] Cooking stoves with a glass ceramic plate providing a
cooking surface, a so-called stove top, have been on the market for
many years in different forms. These systems are embodied as
built-in cooking units, as table-top-cooking units, or as free
standing cooking ranges. They typically have several cooking areas,
also several cooking locations.
[0006] The radiant heating bodies used as heaters for these stove
tops are predominantly electrical devices. The energy transfer from
the source of the heat through the glass ceramic top to the cooking
vessel bottom occurs by heat radiation. The resistor wire of the
radiant heating bodies is heated up to a temperature of about 1300
K. One part of the emitted heat radiation from the heating coil
goes directly through the glass ceramic top into the cooking vessel
bottom or the surroundings in the vicinity of a cooking area when
there is no cooking vessel on the cooking area. The remaining part
of the emitted heat radiation is absorbed in the glass ceramic and
heats the glass ceramic in the vicinity of the cooking area.
[0007] Halogen heating bodies are also used in a small percentage
of the cooking stove tops. Halogen heating bodies operate according
to the same principle as conventional radiant heating bodies.
Generally in this case the heating coil is arranged in a quartz
tube surrounded by a protective gas. The protective gas prevents
contact of the heating coil with oxygen so that it is possible for
the heating coil to operate at temperatures up to about 2400 K.
[0008] Different types of heating coils produce different radiation
spectra, since they operate at different temperatures. The portion
of the heat radiation that goes directly though the glass ceramic
top and the portion that heats the cooking area are also different
for the different types of heating bodies. Also different fractions
of the input energy are delivered as primary heat radiation that
passes directly through the glass ceramic and/or is absorbed by the
glass ceramic and as secondary radiation to the surroundings at the
same nominal power.
[0009] Further development of cooking apparatus has resulted in the
use of the currently different glass ceramic types with different
transmission properties. Because of required product
differentiation current cooking apparatus manufacturers use
different types of glass ceramic material in one and the same base
structure or top structure using the "Panel Forming Engineering"
techniques known from the automobile industry. The different
radiant heading bodies must be individually adjusted to the
different glass ceramics in order to maintain the existing safety
standards and the desired minimum cooking times because of the
different transmission properties of the different glass ceramic
materials and the different emissivities of the different radiant
heating bodies. The adjustment of the heating body output occurs by
means of a temperature-limiting device, which limits the surface
temperature of the cooking surface to a maximum value. This
limiting device is required in order to protect the glass ceramic
cooking surface and the cooking surface surroundings from
overheating by limiting them to a maximum allowable temperature. It
is especially important in the case of a built-in kitchen to limit
the rear wall and side walls of the kitchen fittings along one wall
of a kitchen to a maximum allowable temperature. The specifications
for the surrounding temperatures at the rear wall and side walls of
the kitchen fittings along one wall of a kitchen are given by
safety standard described in EN 60335. The EN 60335, part 1,
section 19, describes a test for determining the rear wall and side
wall temperatures of the kitchen fittings arranged along one
kitchen wall. A maximum temperature increase of 150 K is permitted
during this test. The limiting temperature values of the individual
heating bodies are determined by the ability of the glass ceramic
used in the cooking unit to withstand high temperatures, but of
course can also be determined by the temperature limits for the
rear wall or side walls of the kitchen fittings.
[0010] These problems encountered when different glass ceramics are
used currently may be practically solved only by separately storing
the heating bodies for the different types of glass ceramics, which
is contrary to the use of "Top or Plate Forming Engineering"
methods and means high storage and logistics expenses.
[0011] To maintain and/or reduce the surrounding temperature of the
rear wall and side walls of the cooking stove top DE 10 2004 023
847 A1 teaches formation of the underside of the glass ceramic cook
top with lenses or prisms so that the primary heat radiation from
the heating coil passing through the cooking area remains more
focused in the vicinity of the cooking area and thus the
temperature increase of the walls is reduced. The focusing of the
primary heat radiation should occur by complex structuring of the
glass ceramic underside. For example, structuring the glass ceramic
top underside in the form of a Fresnel lens in the vicinity of the
cooking area is proposed. Furthermore a sort of parallel prism
structure is described, which of course can only act in one
direction, either away from the rear wall or away from the side
walls, but not away from both. However current cooking stove tops
are currently made in a number of different outer geometries and
equipped with different heating bodies. The selection of the
heating body size and arrangement is currently almost completely
arbitrary. The proposed formation of the cooking surface underside
is not possible according to the current state of the art, since
respective individual shaping rollers would be required for shaping
the hot glass sheet of green glass to be ceramicized for each
heating body and the product could not be further modified in
subsequent processing steps. An additional disadvantage of a
full-surface structuring of the underside of a glass ceramic cook
top, for example with prisms or Fresnel lenses, is that a desired
transparency of part of the cooking surface for display devices or
the like is not possible.
SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide cooking
stove tops of the above-described type, which can be equipped with
different glass ceramic tops having different IR transmittances but
which have their different IR transmittances individually adjusted
with economic and variable means, such as coatings, so that the
resulting stove tops have substantially the same IR
transmittance.
[0013] It is another object of the present invention to provide a
cooking stove top comprising a glass ceramic top of type A with
means for modifying its IR spectral transmission properties so that
they are the same or very similar to the IR spectral transmission
properties of a cooking stove top comprising another glass ceramic
top of type B so that these two stove tops are interchangeable,
i.e. so that the modified stove top made comprising a glass ceramic
top of type A can be used in a cooking stove that is designed to
employ the stove top made with the glass ceramic top of type B but
without modifying any other parts of the cooking stove, such as the
temperature-limiting device.
[0014] This object and others, which will be made more apparent
hereinafter, are attained in a cooking stove top, which can be
equipped with at least two different glass ceramic tops with
different IR spectral transmittance (type A, type B), which each
have at least one cooking area, which is heated from below by means
of a radiant heating body cooperating with a temperature-limiting
adjusting device, which limits the surface temperature of the stove
top installed in the cooking stove to a maximum value.
[0015] According to the present invention the stove top comprises
one of the glass ceramic tops has a higher IR spectral
transmittance (Type A) and another of the glass ceramic tops has a
lower IR spectral transmittance (Type B), but the one of the glass
ceramic tops that has the higher IR spectral transmittance is
provided with means for absorbing or reflecting infrared radiation
in order to adjust the spectral IR transmittance so as to be the
same or substantially the same as that of the other glass ceramic
top with the lower IR spectral transmittance which is not provided
with the aforesaid means for absorbing or reflecting infrared
radiation, while retaining the temperature-limiting adjusting
device of the radiant heating body in the cooking stove without any
changes.
[0016] The invention makes it possible to adjust the different IR
transmission properties of different glass ceramic tops used in a
cooking stove in a simple manner so that the different glass
ceramic tops can be used interchangeably in the cooking stove,
while retaining the same expensive temperature-limiting adjusting
device that controls the radiant heating body in the cooking stove
in order to keep the surround temperatures below a predetermined
maximum value.
[0017] In one embodiment of the invention the adjustment is
possible in a surprisingly simple manner by providing an
IR-absorbing or IR-reflecting coating on an upper surface and/or on
a bottom surface of the glass ceramic top. The IR-absorbing or
IR-reflecting coating can extend over the entire upper and/or
bottom surface or it can be applied in a structured pattern or
grid. In this embodiment the manufacture of the raw glass panel is
not influenced and it is still not "individualized" in regard to
the adjustment of its transmission. The coating of the topside or
bottom side of the glass ceramic can occur by known coating
techniques according to the cooking surface size and heating body
configuration designed for the cooking apparatus. Screen-printing
methods have been accepted as standard for the upper surface
coating of the cook top. Screen-printed coatings are also possible
on the underside of the glass ceramic top. However spraying
processes, sputtering techniques or the like can also be used in
principle. Simple application of special decorative patterns, of
cooking area markings, or simple fixing of the degree of coverage
in order to achieve certain transmission values is a significant
advantage to the screen-printing techniques.
[0018] A further possibility for adjusting the IR transmission
and/or reducing the side wall temperatures of kitchen fittings
arranged in a row comprises roughening the underside of the glass
ceramic top. The roughening increases the surface area and produces
a diffuse reflection. The roughening could be produced with a
suitably formed lower side roller for the glass sheet during the
raw glass manufacture or after that by sand blasting. In the latter
case portions of the original surface on the bottom side of the
glass ceramic could be kept smooth during the sand blasting by
means of suitable masks or screens. These smooth portions could be
used for signaling devices and displays, or for printed
information.
[0019] Additional embodiments are claimed in the dependent claims
appended hereinbelow.
BRIEF DESCRIPTION OF THE DRAWING
[0020] The objects, features and advantages of the invention will
now be illustrated in more detail with the aid of the following
description of the preferred embodiments, with reference to the
accompanying figures in which:
[0021] FIG. 1 is a graphical illustration of the dependencies of
the transmissions of two known types of glass ceramics on
wavelength, which also shows the emission spectrum of a known
heating strip with a radiation temperature of 1,300 K;
[0022] FIG. 2 is a graphical illustration of the same dependencies
of the transmissions of two known types of ceramics on wavelength
as in FIG. 1, but shows the emission spectrum of a known heated
halogen body with a radiation temperature of 2,400 K; and
[0023] FIG. 3 is a graphical illustration of the same dependency of
the transmission of a type 1 glass ceramic on wavelength as in FIG.
1, but with different full-surface enamel coatings a, b, and c of
the present invention provided on the glass ceramic.
DETAILED DESCRIPTION OF THE INVENTION
[0024] The emission spectrum of a heated strip with a radiation
temperature of 1300 K is shown in FIG. 1. The transmission in % of
two exemplary glass ceramics of type 1 and type 2 are also
illustrated in FIG. 1. The heating strip has a radiation intensity
maximum at 2200 nm. The type 1 glass ceramic has a transmission of
about 83% at this point and the type 2 glass ceramic has a
transmission of about 78%.
[0025] The basic concept of the present invention is to reduce the
transmission of a glass ceramic top made with the type 1 glass
ceramic by providing a suitable coating or by roughening the
surface in the vicinity of the cooking area sufficiently so that it
corresponds to the transmission of a glass ceramic top made with
the type 2 glass ceramic. Thus the glass ceramic top made with type
1 glass ceramic but provided with the coating or roughening of the
surface is interchangeable with the glass ceramic top made with the
type 2 glass ceramic. As a result it can replace the glass ceramic
top made of the type 2 glass ceramic in a cooking stove without
changing the expensive temperature-limiting adjusting device or
without changing the surrounding temperatures around the stove top.
Enamel paints in different shapes, i.e. with different absorption
and different surface coverage, are used according to the form of
the surface and characteristics of the cooking areas. Laboratory
experiments have shown that a full-surface coating of these enamel
paints can produce a reduction of the IR transmission of up to
about 50% depending on the type of paint that is employed. The
total IR transmission of the stove top comprising the type 1 glass
ceramic top can be adjusted to the IR transmission of the type 2
glass ceramic top by selection of an appropriate color of the paint
and printed pattern.
[0026] The same effect may be obtained by a partially transparent
or reflective coating on the underside of the glass ceramic top.
Noble metal coatings (lustrous paints) comprising gold, platinum,
and palladium components can reduce the heating body radiation by
almost 100%. In this case an embossing or patterning of the coating
and a predetermined coating coverage in the vicinity of the cooking
area is required to adjust the IR transmission of the cook top.
[0027] Experiments have also shown that a SnO.sub.2 coating on the
underside can obtain the same effect. The IR transmission can also
be adjusted when this coating is patterned in the form of a grid or
a screen. Experiments have also shown that it is possible to adjust
the transmission of the glass ceramic by adjusting the coating
thickness.
[0028] Understandably one can also use this principle in order to
handle the problem of a rear wall or side wall temperature that is
too high. In a given cooking system the rear wall temperature can
already be at or above its limiting value depending on the heating
body that it is equipped with or on the heating body power. In this
case also a reduction in the wall temperatures is possible by means
of a specially designed patterned coating provided on the glass
ceramic top according to the above-described embodiments without
making any other changes in the cooking stove.
[0029] FIG. 2 is a graphical illustration similar to FIG. 1, but
includes an illustration of the emission curve of a halogen heating
body with a radiation temperature of 2400 K, in which the radiation
intensity maximum is at about 1200 nm, instead of the emission
curve of the heating body shown in FIG. 1. Since the areas of the
transmission curves of the type 1 and type 2 glass ceramic
overlapping with the area of the emission curve of the halogen
heating body are different from the areas overlapping the area of
the emission curve of the heating strip of FIG. 1, the fraction of
primary radiation in the embodiment corresponding to FIG. 2 is
different from that of the embodiment corresponding to FIG. 1. A
slightly modified patterned coating or coating thickness would be
used in the case of the heating body of FIG. 2 so that the glass
ceramic of type 1 is completely replaceable by the glass ceramic of
type 2.
[0030] FIG. 3 is a graphical illustration showing the reduction of
transmission of glass ceramic top made with a type 1 glass ceramic
by different full-surface enamel coatings (curves a, b, c)
according to the invention. The reduction of the transmission,
especially in the case of the curves c and b, shows that there is
great flexibility availability regarding the choice of patterned
decoration and/or surface coating for adjustments of one type of
glass ceramic to another.
[0031] The possible variations are even greater when a metallic
coating with a reflectivity of almost 100% is used on the underside
of the glass ceramic. Furthermore a combination of a coating on the
underside and the topside in different patterns is conceivable.
[0032] While the invention has been illustrated and described as
embodied in interchangeable glass ceramic tops for a cooking stove,
it is not intended to be limited to the details shown, since
various modifications and changes may be made without departing in
any way from the spirit of the present invention.
[0033] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic or
specific aspects of this invention.
[0034] What is claimed is new and is set forth in the following
appended claims.
* * * * *