Device for protecting rims in glass or ceramic bodies

The invention provides a device for clasp the rims of openings in shaped bodies made of glass ceramic, glass or ceramic, especially openings for the passage of atmospheric gas burners on cooking hobs or stovetops, from mechanical damage and for preventing soiling and damage to arrangements situated underneath the shaped body owing to the ingress of liquids through the openings in the shaped body. The clasp reaches over the rim of the respective opening and extends onto both the top and bottom sides of the shaped body. A sealing and/or heat-insulating material is advantageously inserted between the shaped body and the clasp.

SUMMARY OF THE INVENTION 
The invention relates to a device for protecting the rims of openings in 
shaped bodies made of glass ceramic, glass or ceramic, especially from 
mechanical damage, and for preventing soiling and damage to arrangements 
situated underneath the shaped body owing to the ingress of liquids 
through the openings in the shaped body. In particular, the invention 
relates to a device for protecting openings in cooking hobs or stove tops 
for the passage of atmospheric gas burners. 
On known gas stovetops, gas ranges or cooking hobs with burner arrangements 
of this kind, the gas burners are mounted in a fixed manner in the 
supporting frame or housing. A glass plate, in particular a prestressed 
glass plate, covering the area surrounding the gas burners is provided 
with an opening which is considerably larger than is actually necessary 
for the respective gas burner. The wide annular gap thereby formed between 
the gas burner and the rim of the opening is covered with a simple annular 
collar made of sheet metal. Although this ensures mechanical separation of 
the gas burner from the glass plate, this way of installing the gas burner 
in the glass plate has disadvantageous effects in practical use, 
particularly with respect to cleaning characteristics. It is, for 
instance, possible with these devices for material that has boiled over to 
enter the joint between the prestressed glass plate and the sheet-metal 
collar. Cleaning these devices is difficult and may even require in many 
cases at least partial disassembly. 
Furthermore, such connections have a large number of individual parts and, 
as a result, are expensive and their assembly is very involved. 
DE 41 33 409 C2 (see also U.S. Pat. No. 5,313,929) discloses a burner 
arrangement, intended, for example, for cooking hobs, in which at least 
one gas burner is mounted in a supporting frame and the area surrounding 
the gas burner is covered by means of a shaped body made of glass, glass 
ceramic or ceramic. Each gas burner projects above the top side of the 
shaped body through an opening in the latter. A permanently elastic 
connecting and sealing device with a connecting and sealing element, which 
engages firmly and in a liquid-tight manner on the rim area of the opening 
and on at least one connecting surface formed by the gas burner, is fitted 
between the shaped body and each gas burner. The gas burner is thus 
supported by the shaped body. Also, securing and holding devices are 
fitted between the gas burner and the supporting frame. These devices help 
to retain and secure each gas burner against rotation--while at the same 
time permit limited movement--if the shaped body breaks and thus loses its 
load-bearing ability. 
The assembly of this burner arrangement is a complex operation. Moreover, 
although adhesive bonding solves the problem of providing mechanically 
rigid joints, it is a disadvantage when it comes to recycling, assembly 
(due, for example, to the drying time required by the silicone adhesive) 
and servicing. 
U.S. Pat. No. 5,046,477 discloses the possibility of improving the sealing 
of a burner relative to a glass or glass-ceramic shaped body. In this 
case, the opening in the shaped body is made only as large as it needs to 
be to accept the gas burner. For the purpose of sealing, the gas burner is 
firmly connected to the glass or glass-ceramic shaped body at the rim of 
the opening. The gas burner is furthermore attached to a bracket connected 
to the supporting frame. 
When the cooking surfaces are subjected to mechanical or thermal loading, 
however, a mechanically rigid connection of this kind between a brittle 
shaped body, a supporting frame and the gas burners gives rise to stresses 
in the shaped body. In the case of a cooking hob, gas stovetop or gas 
range, the risk that the shaped body will break is considerably increased 
in all such cases. 
Therefore, an object of the invention, in regard to a burner arrangement of 
the type described above, is to provide a sealing and/or heat-insulating 
protection device between a gas burner and the shaped body made of glass 
ceramic, glass or ceramic, which device is fully effective for practical 
use and is also easy to clean. 
A further object is to provide such a protective device which ameliorates 
or eliminates the risk of breakage due to stresses. 
At the same time, another object is to provide such a protective device the 
assembly of which can be performed in a simple manner, without adhesive 
bonding work and with little expenditure of time, material and money. 
A further object underlying the invention is to pass atmospheric gas 
burners through the shaped body and position them safely and in a suitable 
manner and to provide edge protection for the rim of the hole. 
Upon further study of the specification and appended claims, further 
objects and advantages of this invention will become apparent to those 
skilled in the art. 
To achieve these objects, the invention proposes using a clasp which 
reaches over the rim of the respective opening and onto the shaped body 
onto both the top and bottom sides thereof. In a particularly preferred 
embodiment, a sealing and/or heat-resistant material is inserted between 
the shaped body and the clasp. 
According to the invention, the clasp has a body, which has a smaller 
diameter than the opening in the shaped body, and a collar which is 
connected to one end of the clasp body. The collar bends through at an 
angle of at least 90.degree. away from the axis of the body and its outer 
edge ends, preferably, level with the shaped body, i.e., the outer edge of 
the collar preferably rests on the top surface of the shaped body. At the 
other end of the clasp body there are provided at least three, especially 
eight or more, bendable tabs which can be bent away from the axis of the 
body in the direction of the plane of the shaped body. The clasp thereby 
formed is fixed in a stable manner onto the shaped body. The clasp is 
clamped to the shaped body, on the one hand, by means of its tabs--which 
can be bent through at least 90.degree. away from the axis of the 
body--which reach over one side of the shaped body and, on the other hand, 
by means of the collar, which rests on the other side of the shaped body. 
The clasp body is preferably cylindrical in shape although it is also 
possible to use other circular shapes, e.g., frustoconical, for protecting 
circular openings in the, for example, glass-ceramic stove top. If the 
openings in the shaped body are noncircular, the shape of the clasp body 
can be appropriately modified to conform thereto. The collar can rest 
level on the top surface of the shaped body or, for example, the collar 
can be sloped downward so that its outer edge rests on the top surface of 
the shaped body. 
In a preferred embodiment, in addition to the bending tabs which extend out 
over the rim area of the opening in the shaped body on one side thereof, 
the clasp has further tabs, which project into the area of the opening and 
thus can serve as means for supporting a surface formed by the gas burner. 
Alternatively, a portion of the collar, as well as tabs, can project into 
the area of the opening and form two, e.g., parallel, planes between which 
a surface formed by the gas burner can be held. This embodiment 
considerably simplifies the positioning and centering of the gas burner. 
The clasp can be of one-piece design and the tabs can be designed as 
bending tabs. However, it is also sometimes advantageous for the clasp to 
be of multi-part design wherein the parts which form the clasp can be 
connected together by press fitting, soldering, adhesive bonding, 
screw-fastening or by means of a bayonet joint. In this multi-piece 
variant, the tabs are also preferably designed as bending tabs. 
Since the openings in the shaped bodies made of glass ceramic, glass or 
ceramic are generally round, the clasp is consequently preferably designed 
as a clasp ring with a cylindrical body. In a further preferred 
embodiment, the clasp ring is designed as an open prestressed spring 
element which presses itself against the rim of the opening in the shaped 
body. 
The clasp can be made from a variety of suitable materials including, for 
example, aluminum and deep drawn, cold rolled (stainless) steel. 
In a further advantageous variant of the invention, the clasp has a collar 
at one end of the cylindrical body, and a simple clamping element, in 
particular a metallic clamping ring, which surrounds the body is 
positioned at the other end of the cylindrical clasp body. The clamping 
element is fixed in a defined manner on the clasp body, in particular by 
notches and/or by bends in the clasp body. 
All embodiments of the protective device according to the invention have in 
common that a sealing and/or heat-insulating material, especially a 
temperature-stable, graphite-containing material and/or a ceramic 
composite fiber material is expediently inserted between the shaped body 
and the clasp. 
On the top side, the seal performs the task of forming a liquid-tight 
barrier between the clasp and the glass ceramic, glass or ceramic against, 
for example, material that has boiled over and/or cleaning agents. On the 
underside, the seal protects the shaped body from mechanical scratching 
and damage by the metal. 
It may be advantageous for the collar of the clasp to have openings for the 
air supply to the gas burner, in particular in the area surrounding the 
body. The openings for the air supply are positioned or covered in such a 
way as to repel moisture. 
In a particularly preferred embodiment of the protective device, the rims 
of the collar or tabs, in particular, the rim of the collar of the clasp, 
are bent toward the shaped body in such a way that the sealing and/or 
heat-insulating material is held under compressive stress.

DETAILED DESCRIPTION 
FIGS. 1a and 1b show a one-piece clasp ring (1) with a collar (2) which 
runs around the opening (5) and overlaps onto to the top surface of the 
glass-ceramic plate (3). The clasp ring (1) also overlaps the rim (7) of 
opening (5) with a body (4) which has a smaller diameter than opening (5). 
Formed on the end of the body (4) are tabs (6) (at least 3 and preferably 
8), which are simply bent outward from the interior of opening (5) through 
90.degree. and over the glass-ceramic plate (3), thus clamping the ring 
(1) firmly on the rim (7) of the opening (5) in the glass-ceramic plate 
(3). 
Variants of a one-piece clasp ring (1) are shown in FIGS. 2a and 2b. In 
these variants, the overlapping collar (2)/(2') runs around the opening 
(5) and overlaps the top side of glass-ceramic plate (3). Simultaneously, 
the collar (2)/(2') passes inward over the rim of opening (5) at the top 
side of the glass-ceramic plate (3) and there serves as a support for the 
burner (not shown). 
FIG. 2c shows a preform of particularly simple configuration for a clasp 
having a collar (2) which overlaps onto the top side of the glass-ceramic 
plate (3), a body (4) with bending tabs (6) and also, in addition, a 
further part of the collar (2') which extends into the area of the opening 
(5) in the shaped body (3). 
FIG. 3 shows a one-piece clasp ring (1) in which the overlapping collar 
(2)/(2') simultaneously passes into the area of the hole (5) at the top 
side of the shaped body (3) and there serves as a support for the burner 
(8). The tabs (6)/(6') at the other end of the body (4) are bent 
alternately outward over the bottom of the glass ceramic plate (3) and in 
the other direction over part of the burner (8). 
FIG. 4 illustrates a two-piece clasp ring (1). Two rings, one for the top 
side (1') and one for the under side (1"), with encircling overlaps, i.e., 
collar (2) and tabs (6) and matching body diameters (4)/(4') are inserted 
one into the other from above and below and in this way protect the rim 
(7) of the hold. The matching of the body diameters must be such that the 
pair of rings (1')/(1") cannot come apart by itself. This can be achieved, 
for example, by a press fit between the two parts. In such a case, the 
edge of top ring (1') can overlap that of bottom ring (1") (as shown) or 
vice versa. Another possibility is to join the two rings (1')/(1") 
together by, for example, soldering or adhesive bonding. 
FIGS. 5a, 5b and 5c show three possible variants of a two-piece embodiment 
of the protective device according to the invention. In these variants, 
the overlapping collar (2)/(2') simultaneously passes into the area of the 
opening (5) at the top side of the shaped body (3) and there serves as 
support for the burner (not shown). 
FIG. 5d illustrates a partial section of a two-piece embodiment in which 
the overlapping collar, as well as tabs, project inward into the area of 
the opening to form two parallel planes (2') and (6') for the purpose of 
fastening and positioning the gas burner (8). If desired, the rings 
(1')/(1") can be joined together by soldering, adhesive bonding or by 
clips. 
FIGS. 6a and 6b illustrate a variant of the invention in which a clasp ring 
(1), split in the direction of the cylinder axis, is inserted as a spring 
element into the opening (5) in the shaped body (3). 
In the opening (5), the spring prestress presses the ring (1) against the 
rim (7) of the opening, thus providing a protective device which extends 
over the rim (7) of the opening (5) at its top by plane (2) and at its 
bottom by plane (6). 
According to FIGS. 6c, 6d and 6e, it is also possible in the case of a 
clasp ring (1) split in accordance with FIGS. 6a/6b, for overlapping 
collar (2) to extend inward into the area of the opening (5) in the shaped 
body (3). 
In all the embodiments of the protective device according to the invention 
which have been considered, it is desirable, as shown in FIG. 7, to have 
seals (10)/(10') fitted between the shaped body (3), e.g., a glass ceramic 
plate, and overlapping collar (2) and/or tabs (6) of the clasp (1). Thus, 
seals can be provided on the top surface of the shaped body (3) and, where 
possible, also on the bottom surface. 
On the top surface, the seal (10) performs the task, in particular, of 
forming a liquid-tight barrier against the ingress of material that has 
boiled over and/or cleaning agents, for example, between the clasp (1) and 
the glass ceramic, glass or ceramic shaped body. On the underside, the 
seal (10') protects the shaped body (3) from mechanical scratching and 
damage by the metal tabs (6). 
FIG. 7 furthermore shows a special variant of the clasp (1). In this 
variant, the outer edge of overlapping collar (2) is bent toward the 
surface of the shaped body (3) and, by virtue of its design, holds the 
seal (10) under pressure. 
In the variant shown in FIGS. 8 and 9, air inlets (11), through which the 
gas burner (8) can draw in its primary air, are provided in a uniformly 
distributing manner on the circumference of the collar (2). This clasp 
ring (1) is fixed in the drill hole or opening (5) in the same way as the 
other rings were, namely by bending over the tabs (6). 
At the same time, the other end of collar (2) can serve as a support for 
the gas burner (8). To ensure that no material that has boiled over or 
water used for rinsing can get through the air slots into the interior of 
the hob during cleaning or during cooking, the clasp ring (1) is covered 
with a decorative ring (12), which is simply placed over ring (1). The 
decorative ring (12) merely rests loosely upon the shaped body (3) and is 
fixed on the burner housing. To allow the primary air required to enter 
nevertheless, small feet are formed all the way round the bottom edge of 
decorative ring (12), leaving defined gaps (13) between the decorative 
ring (12) and the glass ceramic (3). 
FIGS. 10 and 11 illustrate yet another embodiment of the invention, in 
which the clasp ring (1') is inserted as a spring element. The ring (1') 
has a collar (2) at one end of the body (4) and a simple metallic clamping 
element (15), forming a second ring (1"), is positioned at the other end 
of the body (4) and surrounds the body (4). The clamping element (15) is 
here fixed in a defined way, e.g., by a nose-shaped bent portion or ledge 
(14) of the ring (1'). The clamping element (15) slips over the clasp body 
(4) so that it is inserted between the shaped body (3) and the peripheral 
ledge (14). The ends of clamping element (15) have ring-shaped openings to 
facilitate assembly using tongs adapted therefor. 
The present invention discloses a simple and inexpensive means of allowing 
gas burners to be passed through a glass or glass-ceramic plate and of 
protecting the rims of the openings during assembly and against ingress of 
liquids during use. These means have advantages during assembly and in the 
case of servicing, allow the maximum possible freedom of design. At the 
same time, these means are elegant, easy to clean and economical to 
manufacture. 
Advantages of the invention include the following: 
there is no mechanically rigid connection between the glass ceramic, glass 
or ceramic body and the gas burner. This is necessary to allow the energy 
which arises during mechanical loading of the shaped body to be absorbed 
without the shaped body being broken, 
in the event of breakage, something which can never be ruled out with 
glass/glass ceramic/ceramic bodies, there is the assurance that the gas 
supply conduit to the gas burner will remain intact and leak-tight, 
the rim of the burner opening is protected from impermissibly high 
mechanical loads, 
there is the assurance that no material that has boiled over or other 
liquids can run into the interior of the stove or cooker, 
there is little assembly work involved, and this means also that 
the servicing work involved in the replacement of defective components or 
the replacement of jets, e.g., for different types of gas, is easy and 
inexpensive. 
Without further elaboration, it is believed that one skilled in the art 
can, using the preceding description, utilize the present invention to its 
fullest extent. The preferred specific embodiments are, therefore, to be 
construed as merely illustrative, and not limitative of the remainder of 
the disclosure in any way whatsoever. 
The entire disclosure of all applications, patents and publications, cited 
above, and of corresponding German application P 44 42 572, filed Nov. 30, 
1994, are hereby incorporated by reference. 
The preceding can be repeated with similar success by substituting the 
generically or specifically described reactants and/or operating 
conditions of this invention for those used herein. 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of this invention, and without departing 
from the spirit and scope thereof, can make various changes and 
modifications of the invention to adapt it to various usages and 
conditions.