Note: Descriptions are shown in the official language in which they were submitted.
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TITIE
Cooking Apparatus
FIELD OF T!~ INVFNTION
The invention relates to a cooking apparatus
with a cooking surface formed by flattened tubular
heating bodies, on which cooking vessels can stand
and in which the tubular heating bodies rest on a
support and are arranged above a closed surface.
BACKGI~OUND O~ TI~E INVENTION
Cooker plates of this type, for example as
described in German Patent No. 1,189,217, have a
relatively small thermal capacity and are therefore
quite suitable for rapid initial cooking procedures
when small amounts of product are to be cooked.
They do however have the substantial drawback
that they do not form a cloæd cooking surface so that
if material which is being cooked overflows, it can run
past them into the interior of the cooker whence it
can be removed later on only with difficulty. The
~o entire cooker surface is therefore made to be pivotal
so that the interior of the cooker can be cleaned.
The cooker unit has a dish which collects the material
which has overflowed. This dish lies at a substantial
distance below the spirally wound twbular heating bodies.
~oreover, these known tubular cooker plates have the
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disadvalltage that -their temperaturc can be controlled
ollly poorly.
A cooker unit is also known from U S. Patent
No. 1,979,471, in which the cooking surLace is formed
by a ceramic plate with deep spiral grooves which
are open at the top and in which lie heating coils~
A radiant heating means is thus formed since the
ceramic plate transfers the heat only poorly. In
this case, cooking material wllich has overflowed
is particularly unpleasant because it runs directly
on to the open heating elemen-ts and sticks to them
or shor-t-circuits them under certain circumstances.
Moreoever, heating elements of this type in the form
of open resistance wires are objectionable for
safe-ty reasons.
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BRIEF SUMMW~Y OF TIE INVENrrION
An object of the present invention is to
provide a cooker unit with a cooking surface formed by
tubular heating bodies, which is superior to known
cooker units, in particular with respect to the
ability to keep it clean
According to the invention there is provided
a cooking apparatus comprising a substantially flat,
thin-walled pla$e provided with grooves, and forming a
closed surface, and flattened tubular heatin6 bodies
arranged in the grooves and forming a cooking surface
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for receiving cooking vessels.
In accordance with a particular embodiment of the
invention, a cooking apparatus comprises a plate extending in a
generally flat plane, provided with grooves, and forming a
closed surface a plurality of longitudinally spaced support
projections disposed in the grooves' and electrically heated
tubular heating bodies with flat upper surfaces, the heating
bodies being arranged on the support projections in the grooves
and forming a cooking surface for receiving cooking vessels,
substantially point contacts being made between the plate and
the heating bodies.
The apparatus according to the invention has the
advantage over conventional tubular cooker plates that it has
a substantially closed cooking surface beyond which the tubular
heating bodies need project only slightly.
The tubular heating bodies can penetrate the thin-
walled plate in a sealed manner so that there is no fear of
cooking material running through in a downward direction. Al-
though the tubular heating bodies lie partially in the grooves,
sufficient lies beyond them for them to form the coo~ing surface.
The plate reaches high temperatures very rapidly owing to its
thinness, forms an additional reflecting and radiating surface,
and allows food which overflows and which collects in the
grooves to be baked into fine ash which can be removed, for
example, by being blown or brushed out. The cooker plate is
thus preferably self-cleaning.
In order to keep the transfer of heat by
contact between the flat thin-walled plate and the tubular
heating bodies rélatively low, the tubular heating bodies can
be supported by support projections lying at a distance from
each other and arranged in the grooves. The projections are
preferably formed by stampings on the base of the grooves.
The generally flat, thin-walled plate, which is
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preLcrably produced from stainless steel, can withstand
the considerable thermal and mcchanical stresses
caused by thermal expansion particularly well if
the grooves are arranged spirally to correspond to
the tubular heating bodies containe~ in them and impart
to the plate a radial elasticity for taking up the
thermal stresses. In this arrangement, the plate works
as a diaphragm with corrugated profiling.
The thin diaphragm-like plate is prelerably
borne by an internal support which can lie, for example,
in a substantially closed -trough of the cooker plate.
The cooker plate thus needs to have only relatively
small openings and this increases its stability. Good
insulating material can also be inserted there, and
this increases ef~iciency and keeps small the thermal
load on the cooker or on items of kitchen furniture lying
beneath a fitted cooker trough, even in the case of a
very small structural height. As the diaphragm-like
plate with the tubular heating body arranged on it
- 20 forms a thermally substantially coherent but tight uni-t,
it is also possible to arrange temperature monitoring
instruments9 for example temperature limiters, beneath
the plate without their temperature sensors being exposed
to dirt or damage. 'rhe above-mentioned small structural
height should ba mentioned because there is no need for a
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collectillg di6h Lor iood whicll hus ovcrLlowcd,
with a throw-away i`oil which can be optionally
insel ted.
An embodiment of the invention is
5ShO~l in the acco~npanying drawings.
BRIEr'' I)ESCT~Il'TION ol? TEIE DI~AWINGS
Figure 1 shows a cross-section throu~h a
cooker unit according to the invention;
Figure 2 shows a plan view o~ the cooker unit
l0according to Figure l;
Figure 3 shows a view along the line III-lII
in Figure 1 (view from below a unit);
Figure 4 shows an enlarged cross-section of
the detail lying in the dash-dotted circle IV in Figure l;
Figure 5 shows a longitudinal section thereof;
and
Figure 6 shows a schematic circuit diagram
of the cooker unit.
DETAILED l)ESCllIP'rION OF PI~EEE~ ED EMBODIMENT
The cooker unit 11 illustrated in the draw~ings
has tubular heating bodies 12 which have a substantiall~
triangular cross-section which is flattened on their
upper side. The upper fla-ttened side forms the cooking
surface 13 on which cooking ~essels 14 can s-tand. The
25tubular heating bodies 12 form two heating resistances
which are wound spirally. An internal heating resistance 15
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is surroullded by an external heating resistance 16,
the internal elld oi` the heating resistance 16
being connected directly to the external end of the
heating resistance 15. The heating rcsistance 15 thus
5 forms a central heating zone while the heatin6 resistance
16 forms an external heating ring.
The tubular heating bodies have relatively
small cross-sectional dime~sions, the largest dimension
of which (a triangular side) amounts to about 5 mm,
lO and are therefore ~ite flexible and are well adapted to
the heated surface of the cooking vessel 14. They
can be made of a rust-resistant metallic casing and
substantially coil-shaped hea-ting conductors in an
insulating embedding composition embedded therein.
15 Owing to the triangular shaping, the cross-section
of the coil is also approximately triangular.
The tubular heating bodies lie on a thin
plate 17 which is made of very thin stainless steel
p~te with thicknesses of the order of 0.2 to 0.4 mm.
20 Spiral grooves 18 having a substantially triangular
cross-sectional shape (with rounded corners) are shaped
- into the circular pla-te 17 to correspond to the spiral
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shape of th0 heating resistances ~ land ~. Support
projections 19 are arranged on th0 bottom of these grooves
~5 at intervals of a few centimetres. In the illustrated
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embodimcllt, eight support pr~jections 19 are pro~ided
round the circumference d`the grooves, with the exception
of the internal spiral windings.
The support projections 19 are formed by the
fact that in each case the bot-tom of each groove is not
5shaped to the full depth over a distance o~ a few
millimetres.
As shown, in particular, in Figure 4, the
lower triangular edge of the tubular heating bodies
lies virtually in point contact on the support
projection 19 which is also rounded in side view
(Figure 5).
The groove 18 is sufficiently large for -the
tubular hea-ting body to lie in it at a distance of
from 1 to a few millimetres and with the cooking surface
1513 projects somewhat beyond the flat surface of the plate
17.
~ he two ends ol` each heating resistance 15,16
are passed in a sealed manner through openings 20.
In the embodiment illustrated, they are soldered
20into these openings. A completely sealed cooker unit is
thus produced so that overflowing ioods cannot run inside
the cooker or cooker trough. Although some overflowing
food will stick in the grooves and under the tubular
heating bodies, this space in the grooves is designed
25to be such that, havïng regard to the thinness of the wall
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of the plate 17 it cleans itself as a result oL the
carbonisation of the food which has overflowed. A line
ash which can be blown or brushed out is thus Iormed.
The extremely high temperatures which produce this
self-cleanin~ effect are produced only when there is
5 dirt in these positions. If the blank metal surLace
is exposed, the groove acts as a reflector which irradiates
the heat radiation ori~inating fro~ the underside of the
tubular heating body upward toward the bottom of the cooking
vessel. The groove can al~ be designed in other ways
10 so as to obtain specific coefficients of reflection and
so as not to fall below desired minimum distances between
tubular heating bodies and plate. Thus, for e~ample,
it could also be of substaltially semi-circular cross-
section in the case of a tubular heating body designed
15 semi-circularly on its underside. The support projections
could also have another sequence or design. However,
it is preferable to stamp them directly from the material
of the plate.
The plate 17 has a relatively wide unheated
20 edge region 21 between the outermost spiral winding of
the heating resistance 16 and its external edge, which
ensures that only a very little heat can be conducted
toward the edge, owing to the relatively poor heat
conducting properties of stainless steel. On the outer
~5 circumference, the plate 17 is beaded downward round the
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cxt,~rllal ~ge 21 of a dish-like disc 22 and thus joined
to it. The disc 2'' Lorl~s a sup~)ortillg s-truc-ture for the
plate 17. It has a projection 24 directed wpwar~s in
its centre so that its recess 23 surrounclsthe projection
24 in the manner of a groove. The recess 23 in the disc 22
5 is relatively flat. Support projections 25 are shaped
Lrom the disc, which project upwards into its reces~ 23
and are dimensioned in such a way that the underside of
the grooves 18 rest on them. As shown in Figure 3,
the support projections are formed by cutting into the
material of the disc and formed upwardly directed flanges
which run radially. The pla-te 17 is borne by the support
projections, as well as by tlle central projectionformed
by deep stamping of the material of the disc so that
even heavy cooking vessels do not produce unacceptable
deformation of the plate 17. It should be noted that
the plate 17 acquires the properties of a corrugated
diaphragm owing to the spiral grooves 18 so that it can
compensate even extreme temperature differences without
unacceptable deformations. The pxojection 21~ can he
welded to the plate 17.
The disc 22 is produced from thicker and
more rigid material than thc plate 17 and can have a
reflecting surface in its interior. It is also possible
to insert an insulating material 26 in it (shown in part
in Figure 1~.
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A tempera-ture limiter 27 can be arrange~ in
the cavity 23 between plate 17 and disc 22, preferably
in the edge region, and serves to switch off the cooker
unit when an excessive temperature occurs (Lor example
5 in no-load operation).
A fixing bolt 28 with which the unit 11 can
be fixed on a cooker or a cooker trough, is arranged-
in the region of the central projection 24.
As shown in Figure 1, the plate 29 in which
the unit is fitted can have a relatively flat trough
30 which need be, for example, only 20 to 30 mm deep.
This trough 30 can -be substantially uninterrupted up
to the openings for the ends of the tubular heating
body and the central bolt so that the plate 29 has a
15high inherent stability~ Insulating material 31 can
be inserted between the trough and the unit 11 lying
in it at a small distance (indicated in part in Figure 1).
On its encircling edge, the trough has an
encircling shoulder 32 lying somewhat deepended, on which
20the edge 21 of the unit 11 is supported with interpesition
of a sealing ring 33. The unit 11, which is~ furthermore,
only kept down by the fixing bolt 28 is there~ore tightly
inserted into the plate 29. The surface of the plate 17
can therefore lie flush with the surface of the plate 29
25to form a surface on which saucepans can be slid to and
fro without encounte~ing ledges. The small distance
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tWCell the plate 17 and tlle heatin~ surrace 13 on
the tubular hea-ting bodies 1'' is thus easily overcome.
It should also par-ticularly be no-ted that -the
unit 11 forms a separate unit which can be mounted
in advance and produced separately from the re6t oL
the cooker and which can easily be placed on the cooker
and exchanged if in need of repair. The total height
oI the cooker trough can be kept very small owing to
the good and multiple means of insulation wi-thout
the temperature exceeding an allowable value on its underside.
Flat incorporation in kitchen furniture is thus possible.
As shown in Figure 6, the two hea-ting resist-
ances 15,16 can be switched on separately. The temper-
ature limiter 27 and a power control instrument 36 which
usually operates by quantization, lies in a common
supply line 35. A bimetallic member 38 heated by a
control heating resistance 37 which is connected in
parallel with thel-eating resistances activates a switch
39 of the power control instrument. The power control
instrument can be set by means of an actuating button 40.
A manually activatable mechanical switch 41 which lies
in the supply line to the external heating resistance
16 is also provided. If~ for example, the external
diameters of the internal heating resistance 15 and
the external heating resistance 16 are 140 and 180 mm,
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houscwivcs call choosc whc1llcl they wisll to use only a
slllall or a large hcated diamcter, de~erlding upon the
si~e of the saucepan use~ A very adal)tablc cooking
unit with which energy can bc saved iS thus provided.
It would also be possible to have the.switch
5 41 switched automatically by activating the activating
button 40 in such a way that the heating resistance 16
is only connected in the uppcr power range, i.e. when
the power control instrument 36 has controlled the
internal heating resistance to lrom 15 to 100% power.
10 Control is continued as a result of a l~ink in the
corresponding control curve of the power control
instrument 36 once the heating resistance 16 has been
connected in the case of the corresponding power value.
It is however also possible -to design the circuit in
such a way that the heating ~ody 15 remains entirely
connected in the higher power range and the energy
controller merely controls t~le heating resistance 16. :
IIowever, in each case, the advantage is achieved that
only the internal heating resistance is effective at
20 low power This promotes saving in energy, i.n particular
~-~ because, at the very moment when only small power is
necessary, i.e. small amounts of food are to be heated,
coo~ing vessels which are small and which do not cover
the entire cooker unit are frequently selected. Moreover,
25 particularly in the lower power range which is difficult
~ to start up, the power control instrument controls only
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-tlle power of the heating resistance 15 and thus receives
higher relative switc~hing times than would correspond to
the respective portion oL thc total power of the cooker
plate.
The use of two heating resistances 15, 16
in the case of a normal or large plate diameter also
has the advantage that only the central heating resistance
15 need be provided ior s~all plate diameters. A
reduction in the number of types of heating resistances
with corresponding advantages for production and storage
can be achieved in this way.
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