Abstrict
A radiant electric heater comprises a dish-like component (1) of
thermal insulation material having a base (2) and an upstanding
peripheral wall (3). At least one heating element (4) is supported
inside the dish-like component, and reinforcing means (5) is secured
to the outside of the dish-like component at the outside thereof.
The reinforcing means (5) comprises at least one strip (6, 7; 6A,
7A) extending across the base (2) and at least partly up the peripheral
wall (3) of the dish-like component (1).
Claims
What is claimed is:
1. A radiant electric heater comprising a dish-like component of
thermal insulation material having a base and an upstanding peripheral
wall, at least one heating element supported inside the dish-like
component, and reinforcing means secured to the dish-like component
outside thereof, wherein the reinforcing means comprises at least
one strip extending across the base and at least partly up the peripheral
wall of the dish-like component, the reinforcing means being substantially
continuously in contact with the dish-like component across the
base thereof.
2. A radiant electric heater according to claim 1, wherein the
at least one strip has opposite ends thereof extending at least
partly up the peripheral wall.
3. A radiant electric heater according to claim 1, wherein the
reinforcing means comprises at least two strips extending at an
angle to one another across the base and at least partly up the
peripheral wall of the dish-like component.
4. A radiant electric heater according to claim 3, wherein two
strips are arranged substantially orthogonal to one another.
5. A radiant electric heater according to claim 3, wherein the
at least two strips are provided as separate components crossing
one another.
6. A radiant electric heater according to claim 3, wherein the
at least two strips are secured to one another.
7. A radiant electric heater according to claim 3, wherein the
at least two strips are provided as limbs of a single integral component.
8. A radiant electric heater according to claim 1, wherein a terminal
block is secured to the reinforcing means.
9. A radiant electric heater according to claim 8, wherein the
terminal block is secured to at least one portion of the at least
one strip of the reinforcing means which extends at least partly
up the peripheral wall.
10. A radiant electric heater according to claim 1, wherein a temperature
limiting device is secured to the reinforcing means.
11. A radiant electric heater according to claim 10, wherein the
temperature limiting device is secured to at least one portion of
the at least one strip of the reinforcing means which extends at
least partly up the peripheral wall.
12. A radiant electric heater according to claim 1, wherein the
at least one strip of the reinforcing means is secured to the dish-like
component at the peripheral wall thereof.
13. A radiant electric heater according to claim 12, wherein the
reinforcing means is secured to the dish-like component by means
of a deformed portion of the at least one strip extending towards
the peripheral wall.
14. A radiant electric heater according to claim 13, wherein the
deformed portion comprises a cut out deformed portion of the at
least one strip extending towards the peripheral wall.
15. A radiant electric heater according to claim 1, wherein the
at least one strip of the reinforcing means incorporates at least
one stiffening rib.
16. A radiant electric heater according to claim 15, wherein the
at least one stiffening rib runs longitudinally along the at least
one strip.
17. A radiant electric heater according to claim 1, wherein the
reinforcing means comprises metal.
18. A radiant electric heater according to claim 1, wherein the
thermal insulation material of the dish-like component comprises
compacted microporous thermal insulation material.
Description FIELD OF THE INVENTION
This invention relates to radiant electric heaters which find particular
application in cooking appliances such as glass-ceramic cooking
appliances.
DESCRIPTION OF PRIOR ART
It has been well known for many years to produce radiant electric
heaters for glass-ceramic cooking appliances in which a layer of
insulation material, particularly microporous insulation material,
is provided in a reinforcing means in the form of a metal dish.
A heating element is supported on or adjacent to the insulation
layer and a peripheral wall of insulation material is provided against
the inside of the side edge of the dish. A terminal block, for connecting
the heating element to a voltage supply, is usually provided secured
to a side edge of the dish.
A temperature limiting device is also usually provided, secured
to the dish and having a rod-like portion extending at least partly
across the heater, over the heating element.
In order to save costs, it has previously been proposed to dispense
with the metal dish and provide a dish-like component of thermal
insulation material inside which at least one heating element is
supported. For maximum thermal efficiency it is preferred that the
dish-like component should comprise compacted microporous insulation
material. However, such material is relatively soft and the dish-like
component may be relatively fragile. Furthermore it is difficult
to secure a terminal block and a temperature limiting device thereto.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome or minimise
these problems.
SUMMARY OF THE INVENTION
According to the present invention there is provided a radiant
electric heater comprising a dish-like component of thermal insulation
material having a base and an upstanding peripheral wall, at least
one heating element supported inside the dish-like component, and
reinforcing means secured to the dish-like component at the outside
thereof, wherein the reinforcing means comprises at least one strip
extending across the base and at least partly up the peripheral
wall of the dish-like component.
The at least one strip may have opposite ends thereof extending
at least partly up the peripheral wall.
The reinforcing means may comprise at least two strips extending
at an angle to one another across the base and at least partly up
the peripheral wall of the dish-like component. The at least two
strips may be arranged substantially orthogonal to one another.
The at least two strips may be provided as separate components crossing
one another and/or secured to one another, or may be provided as
limbs of a single integral component.
A terminal block and/or a temperature limiting device may be secured
to the reinforcing means and suitably to one or more portions of
the at least one strip thereof which extend at least partly up the
peripheral wall.
The at least one strip of the reinforcing means may be secured
to the dish-like component at the peripheral wall thereof. Such
securing may be by means of a deformed portion, for example a cut
out deformed portion, of the at least one strip extending towards
(into or over) the peripheral wall.
The at least one strip of the reinforcing means may incorporate
at least one stiffening rib, which may run longitudinally along
the at least one strip.
The reinforcing means may comprise metal.
The thermal insulation material of the dish-like component may
comprise compacted microporous thermal insulation material.
For a better understanding of the present invention and to show
more clearly how it may be carried into effect reference will now
be made, by way of example, to the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a dish-like component of thermal
insulation material having at least one heating element supported
therein for use in a radiant electric heater according to the present
invention;
FIG. 2 is a perspective view of one embodiment of reinforcing means
for application to the dish-like component of FIG. 1;
FIG. 3 is a perspective view of a radiant electric heater according
to the present invention and incorporating the component and reinforcing
means of FIGS. 1 and 2; and
FIG. 4 is a perspective view of an alternative embodiment of reinforcing
means for application to the dish-like component of FIG. 1.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, a radiant electric heater is provided
which finds particular application mounted beneath a glass-ceramic
surface in a cooking appliance (not shown).
The heater comprises a dish-like component 1 of thermal insulation
material, the dish-like component having a base 2 and an upstanding
peripheral wall 3. The dish-like component is suitably of moulded
form produced by compacting particulate microporous thermal insulation
material in an appropriately-shaped press tool. Microporous insulation
material compositions and moulding techniques suitable for this
purpose are well known to the skilled person.
By way of example, the microporous insulation material may comprise:
Pyrogenic silica 49-97% by weight Glass or ceramic fibre reinforcement
0.5-20% by weight Opacifier (e.g. titanium dioxide) 2-50% by weight
Alumina 0.5-12% by weight
At least one heating element 4 is provided, supported inside the
dish-like component 1. The heating element or elements 4 may comprise
any of the well known forms, such as coiled wire, metal ribbon,
or lamp forms, or combinations thereof. In the illustrated embodiment,
the heating element 4 is a corrugated ribbon partially embedded
edgewise in the upper surface of the base 2 of the dish-like component
1.
The dish-like component is relatively fragile. Reinforcing means
5 is therefore provided, secured at the outside of the dish-like
component 1.
The reinforcing means 5 comprises at least one metal strip, such
as of steel, having a portion 6 extending across and in contact
with the outside of the base 2 of the dish-like component 1, and
one or more portions 7 extending at least partly, and preferably
completely, up the outside of the peripheral wall 3.
A further such metal strip may be provided at an angle to the first-mentioned
strip and comprising portions 6A and 7A similar to the portions
6, 7 of the first strip.
The two metal strips 6, 7; 6A, 7A are suitably arranged substantially
orthogonally to one another. They may be secured together, such
as by welds 8, at a region where they cross one another.
Instead of the two strips 6, 7; 6A, 7A being provided as separate
components crossing one another, they may be provided as limbs of
a single integral cross-shaped component as shown in FIG. 4.
Portions 9, 9A are cut out of the ends 7, 7A of the strips and
deformed so as to extend into or over the peripheral wall 3 of the
dish-like component 1. The reinforcing means 5 comprising the strips
6, 7; 6A, 7A is thereby secured to the dish-like component 1.
In order to stiffen the strips 6, 7; 6A, 7A, they may be provided
with one or more ribs 10, 10A, preferably running longitudinally
along the strips.
A terminal block 11 is secured to one of the end portions 7, of
the strip 6, 7 and is connected through an aperture 12 and a corresponding
aperture in the peripheral wall 3 of the dish-like member 1 to the
at least one heating element 4.
A temperature limiting device 13 is secured either at the opposite
end of the same strip 6, 7 as the terminal block 11 or, as shown
in FIG. 3, at one of the ends 7A of the other strip 6A, 7A. The
temperature limiting device 13, which is of well-known form, has
a rod-like portion 13A extending partly across the dish-like member
1, over the at least one heating element 4, through an aperture
14 in the end portion 7A of the strip of the reinforcing means and
through a corresponding aperture in the peripheral wall 3 of the
dish-like component 1.
As a result of the invention, the reinforcing means 5 provides
inexpensive structural support for the dish-like component 1 of
thermal insulation material as well as providing secure mountings
for the terminal block 11 and temperature limiting device 13.
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