Abstrict
An electric heater (2) is arranged for location in an oven (4)
intermediate a cavity (6) of the oven and a flue arrangement (8)
for venting the cavity (6). The heater (2) comprises a dish-like
support (14) containing at least one electric heating element (22)
and having a first face (24) open to the cavity (6) and a second
face (16; 18) having an aperture (26) adapted to interface with
the flue arrangement (8). Catalyst means (28) is provided incorporated
in the heater (2).
Claims
I claim:
1. An electric heater for location in an oven intermediate a cavity
of the oven and a flue arrangement for venting the cavity, the heater
comprising a dish-like support containing at least one electric
heating element and having a first face open to the cavity and a
second face having an aperture adapted to interface with the flue
arrangement, catalyst means being provided incorporated in the heater.
2. The heater of claim 1, wherein the aperture adapted to interface
with the flue arrangement is provided in the second face of the
dish-like support selected from a base and a peripheral wall of
the dish-like support.
3. The heater of claim 2, wherein the aperture includes a rimmed
portion projecting outwardly from the dish-like support.
4. The heater of claim 2, wherein the catalyst means is located
at or in the aperture in the base or the peripheral wall of the
dish-like support.
5. The heater of claim 4, wherein the aperture is at least partly
bordered by thermal insulation material.
6. The heater of claim 5, wherein the thermal insulation material
comprises microporous thermal insulation material.
7. The heater of claim 2, wherein a base layer of thermal insulation
material is provided in the dish-like support and having an opening
coinciding with the aperture in the base or the peripheral wall
of the dish-like support.
8. The heater of claim 7, wherein the at least one electric heating
element is supported on or adjacent to the base layer of thermal
insulation material.
9. The heater of claim 8, wherein the at least one electric heating
element is arranged with at least one part thereof traversing the
opening in the base layer coinciding with the aperture when provided
in the base of the dish-like support.
10. The heater of claim 9, wherein a supporting member is arranged
in the opening in the base layer for supporting the at least one
part of the at least one electric heating element where traversing
the opening in the base layer.
11. The heater of claim 10, wherein the supporting member comprises
ceramic material.
12. The heater of claim 11, wherein the supporting member is moulded
into, or pressed into, the base layer of thermal insulation material.
13. The heater of claim 2, wherein the catalyst means provided
at or in the aperture in the base or the peripheral wall of the
dish-like support comprises catalyst material on a support means.
14. The heater of claim 13, wherein the support means is selected
from a ceramic member of honeycomb form, a helically coiled metal
foil member, a wire mesh member, and ceramic mesh member.
15. The heater of claim 14, wherein the metal foil member is of
crinkled form.
16. The heater of claim 1, wherein there is provided at least one
apertured member overlying the first face thereof and spaced from
the at least one electric heating element.
17. The heater of claim 16, wherein the apertured member(s) overlie(s)
a peripheral wall of the dish-like support.
18. The heater of claim 17, wherein the at least one apertured
member is selected from woven glass filament material, woven ceramic
filament material and wire mesh material, and combinations thereof.
19. The heater of claim 1, wherein the catalyst means is arranged
at the first face of the heater.
20. The heater of claim 19, wherein the catalyst means overlies
the first face of the heater.
21. The heater of claim 20, wherein the catalyst means is in the
form of a mesh comprising or supporting catalyst material.
22. The heater of claim 20, wherein the catalyst means overlies
a peripheral wall of the dish-like support.
23. The heater of claim 19, wherein at least one apertured member
is additionally provided overlying the catalyst means at the first
face of the heater.
24. The heater of claim 23, wherein the at least one apertured
member is selected from woven glass filament material, woven ceramic
filament material and wire mesh material, and combinations thereof.
25. The heater of claim 1, wherein the catalyst means comprises
a coating on at least part of the at least one electric heating
element.
26. The heater of claim 1, wherein the catalyst means comprises
one or more catalyst materials selected from platinum, palladium,
osmium, iridium, ruthenium, rhodium and mixtures thereof.
27. The heater of claim 1, wherein the at least one electric heating
element is selected from ribbon, wire, foil, lamp and metal-sheathed
form.
28. The heater of claim 1, wherein the dish-like support comprises
metal.
29. The heater of claim 1, wherein a fan means is provided associated
with the flue means.
Description BACKGROUND TO THE INVENTION
[0001] More particularly, the invention relates to an electric
heater for an oven in which smoke or fumes are generated in a cavity
of the oven and are treated by a catalyst assembly during exit from
the oven cavity through a flue arrangement which is provided to
vent the oven cavity.
DESCRIPTION OF PRIOR ART
[0002] It is well known to provide a catalyst assembly in the flue
of an oven to reduce or eliminate smoke or fumes generated either
during a normal cooking operation, or during a high temperature
self-cleaning cycle effected in the oven. Such a catalyst assembly
requires to be heated before it can operate effectively. This is
usually achieved by locating the catalyst assembly in the flue sufficiently
close to the outlet from the oven such that hot air from the oven
heats the catalyst assembly, but such an arrangement is not altogether
satisfactory. In another arrangement, a separate heating element,
such as of metal-sheathed form, is known to be provided up-stream
of the catalyst assembly to more rapidly heat the air approaching
the catalyst assembly. However, such an arrangement is expensive
to implement.
[0003] It is also known to locate a heating element near the top
wall of an oven cavity, with part of the element overlying a flue
opening provided in the top wall of the oven cavity. A catalyst
assembly is again provided in the flue. This can improve the heat-up
rate of air entering the flue and thus accelerate heating of the
catalyst assembly. However, the heating element and the catalyst
assembly are provided as separate components and subsequently mounted
relative to the flue. Such an arrangement is inconvenient to implement.
OBJECT OF THE INVENTION
[0004] It is an object of the present invention to overcome or
minimise the aforementioned disadvantages.
SUMMARY OF THE INVENTION
[0005] According to the present invention there is provided an
electric heater for location in an oven intermediate a cavity of
the oven and a flue arrangement for venting the cavity, the heater
comprising a dish-like support containing at least one electric
heating element and having a first face open to the cavity and a
second face having an aperture adapted to interface with the flue
arrangement, catalyst means being provided incorporated in the heater.
[0006] The electric heater may be arranged for location at a wall
of the oven cavity, such as a wall at the top of the oven cavity
and may be adapted for a cooking purpose, such as grilling.
[0007] The catalyst means may be adapted to reduce or eliminate
passage into the flue arrangement of smoke or fumes generated in
the oven cavity.
[0008] The aperture adapted to interface with the flue arrangement
may be provided in the second face of the dish-like support comprising
a base or a peripheral wall of the dish-like support and may include
a rimmed portion projecting outwardly from the dish-like support.
[0009] The catalyst means may be located at or in the aperture
in the base or the peripheral wall of the dish-like support and
may be at least partly bordered by thermal insulation material,
such as microporous thermal insulation material.
[0010] A base layer of thermal insulation material may be provided
in the dish-like support and having an opening coinciding with the
aperture in the base or the peripheral wall of the dish-like support.
[0011] The at least one electric heating element may be supported
on or adjacent to the base layer of thermal insulation material
and may be arranged with at least one part thereof traversing the
opening in the base layer coinciding with the aperture when provided
in the base of the dish-like support.
[0012] A supporting member, such as of ceramic material, may be
arranged in the opening in the base layer for supporting the at
least one part of the at least one electric heating element where
traversing the opening in the base layer. Such supporting member
may be moulded into, or pressed into, the base layer of thermal
insulation material.
[0013] The catalyst means provided at or in the aperture in the
base or the peripheral wall of the dish-like support may comprise
catalyst material on a support means. Such support means may comprise
a ceramic member of honeycomb form, a helically coiled metal foil
member which may be of crinkled form, or a wire or ceramic mesh
member.
[0014] The electric heater may be provided with at least one apertured
member overlying the first face thereof and spaced from the at least
one electric heating element. Such apertured member(s) may overlie
a peripheral wall of the dish-like support and may comprise woven
glass or ceramic fibre or filament material, and/or wire mesh material.
[0015] The catalyst means may alternatively be arranged at the
first face of the heater, for example overlying the first face of
the heater, such as in the form of a mesh comprising or supporting
catalyst material, and which may be arranged to overlie a peripheral
wall of the dish-like support. At least one apertured member, such
as of woven glass or ceramic fibre or filament material, and/or
wire mesh material, may be additionally provided overlying the catalyst
means at the first face of the heater.
[0016] In a further alternative embodiment, the catalyst means
may comprise a coating on at least part of the at least one electric
heating element.
[0017] The catalyst means may comprise one or more catalyst materials
selected from platinum, palladium, osmium, iridium, ruthenium and
rhodium and mixtures thereof.
[0018] The at least one electric heating element may be of ribbon,
wire, foil, lamp or metal-sheathed form.
[0019] The dish-like support of the heater may comprise metal.
[0020] A fan means may be provided associated with the flue arrangement
in the oven.
[0021] 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
[0022] FIG. 1 is a cross-sectional view of an oven provided with
an embodiment of an electric heater according to the present invention
located outside an oven cavity;
[0023] FIG. 2 is a cross-sectional view of an oven provided with
an embodiment of an electric heater according to the present invention
located inside an oven cavity;
[0024] FIG. 3 is a plan view of the electric heater provided in
the ovens of FIGS. 1 and 2;
[0025] FIGS. 4A, 4B and 4C are perspective views of alternative
catalyst means for use in the heater of FIG. 3;
[0026] FIG. 5 is a plan view of an alternative arrangement of a
heating element in the heater of FIG. 3;
[0027] FIGS. 6A and 6B are perspective views of embodiments of
supporting members for use in the arrangement of FIG. 5;
[0028] FIGS. 7A and 7B are cross-sectional views of alternative
aperture arrangements in a dish-like support of a heater of the
present invention;
[0029] FIG. 8 is a cross-sectional view of an alternative embodiment
of an electric heater according to the present invention, having
an aperture provided in a peripheral wall thereof;
[0030] FIG. 9 is a cross-sectional view of a further embodiment
of an electric heater according to the present invention;
[0031] FIG. 10 is a cross-sectional view of an alternative arrangement
of catalyst means in the heater of FIG. 9; and
[0032] FIG. 11 is a cross-sectional view of a still further embodiment
of an electric heater according to the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] Referring to FIGS. 1 to 3, a radiant electric heater 2 is
located in an oven 4, for example for performing a grilling or other
cooking function. The heater 2 is located in the oven 4 intermediate
a cavity 6 of the oven and a flue arrangement 8 for venting the
cavity 6. Such venting of the cavity 6 is required as a result of
smoke or fumes being generated in the cavity 6 during a cooking
operation or during a high temperature self-cleaning cycle effected
in the cavity 6. A fan 10 may be provided in the flue arrangement
8 to promote exit of air through the flue arrangement 8.
[0034] The oven 4 of FIG. 1 has the heater 2 located at the top
of the oven cavity 6 in a recess in a top wall 12 of the cavity
6, whereas the oven 4 of FIG. 2 has the heater 2 located at the
top of the oven cavity 6, inside the oven cavity 6 and against the
top wall 12 thereof.
[0035] The heater 2 is arranged in the oven 4 between the cavity
6 of the oven and the flue arrangement 8 and comprises a dish-like
support 14, such as of metal, having a base 16 and a peripheral
wall 18. A base layer 20 of thermal insulation material, such as
microporous thermal insulation material, is provided inside the
dish-like support 14.
[0036] At least one electric heating element 22 is supported on
or adjacent to the base layer 20. Such heating element or elements
22 can comprise any of the well-known forms, such as ribbon, wire,
foil, lamp or metal-sheathed forms, or combinations thereof. As
illustrated, the heating element 22 is provided of corrugated metal
ribbon form.
[0037] The heater 2 has a front face 24 open to the oven cavity
6 and has an aperture 26 extending through the base 16 of the dish-like
support 14 and the base layer 20 and interfacing with the flue arrangement
8.
[0038] A catalyst means 28 is incorporated in the heater 2 and
is arranged in the aperture 26 and bordered by the base layer 20
of thermal insulation material. Such catalyst means 28 is heated
by air drawn through the heater 2 from the oven cavity 6 into the
flue arrangement 8. The catalyst means 28 comprises a catalytically
active material which, when heated and contacted by smoke or fumes
from the oven cavity 6, operates to reduce or eliminate the smoke
or fumes which are generated in the cavity 6 during a cooking operation
or during a high temperature self-cleaning cycle effected in the
oven cavity 6.
[0039] The catalyst means 28 suitably comprises a catalyst material
on a support. Such catalyst material may, for example, comprise
one or more of platinum, palladium, osmium, iridium, ruthenium and
rhodium, preferably platinum.
[0040] Examples of catalyst means 28 are illustrated in FIGS. 4A,
4B and 4C. In FIG. 4A, the catalyst means 28 comprises a ceramic
member of honeycomb form coated with catalyst material. In FIG.
4B, the catalyst means 28 comprises a helically coiled metal foil
member, such as of crinkled or corrugated form, coated with catalyst
material. In FIG. 4C, the catalyst means 28 comprises a wire or
ceramic mesh member coated with catalyst material.
[0041] For effective operation, the catalyst means 28 must be heated
to and maintained at as high a temperature as possible. This is
assisted by the thermally insulating base layer 20 which surrounds
the catalyst means in the heater 2.
[0042] The electric heater 2 can be provided with at least one
apertured member 30 overlying the front face 24 of the heater 2
and spaced from the heating element or elements 22. Such one or
more apertured members 30 is or are arranged to be permeable to
smoke and/or fumes generated in the oven cavity 6 and suitably overlie(s)
the peripheral wall 18 of the dish-like support 14 of the heater
2. The one or more apertured members 30 suitably comprise(s) woven
glass or ceramic fibre or filament material and/or wire mesh material.
[0043] Referring now to FIG. 5, in order to ensure that air passing
through the catalyst means 28 is heated to as high a temperature
as possible, at least part of the heating element or elements 22
is arranged to traverse the aperture 26 in which the catalyst means
28 is provided. To prevent sagging of the at least part of the heating
element 22 where crossing the aperture 26, a support member 32,
such as of ceramic material, can be provided, as shown in FIGS.
6A and 6B. In FIG. 6A, the support member 32 is in the form of a
frame arranged in the aperture 26 in the heater 2 and provided with
recesses 34 for receiving and supporting the heating element 22.
In FIG. 6B, the support member 32 is in the form of a beam across
the aperture 26 in the heater 2 and provided with recesses 34 for
receiving and supporting the heating element 22. The support member
32 in FIGS. 6A and 6B may be moulded into, or pressed into, the
base layer 20 of thermal insulation material.
[0044] Referring now to FIGS. 7A and 7B, the aperture 26 in the
base 16 of the dish-like support 14 may include a rimmed portion
36 projecting outwardly from the dish-like support 14 and supporting
the catalyst means 28. As shown in FIG. 7B, the catalyst means 28
is bordered by thermal insulation material 38, for example microporous
thermal insulation material, in the rimmed portion 36 of the aperture
26 in the dish-like support 14. Such thermal insulation material
38 assists in maintaining the catalyst means 28 at as high a temperature
as possible.
[0045] Referring now to FIG. 8, instead of the aperture 26 and
the catalyst means 28 being provided in the base 16 of the dish-like
support 14 of the heater 2, the aperture 26 and the catalyst means
28 are provided in the peripheral wall 18 of the dish-like support
14 and interfacing with the flue arrangement 8. The flue arrangement
8 is arranged for sideways connection to the heater 2. The catalyst
means 28 is bordered by thermal insulation material of the base
layer 20.
[0046] An alternative embodiment of the heater 2 of the present
invention is shown in FIG. 9. This is substantially the same as
the heater shown in FIG. 3 with the important difference that, instead
of the catalyst means 28 being provided in the aperture 26 through
the base 16 of the dish-like support 14, the catalyst means 28 is
arranged to overlie the front face of the heater 2, suitably in
the form of a mesh permeable to smoke and/or fumes and comprising
or supporting catalyst material. Such catalyst means 28 suitably
overlies the peripheral wall 18 of the dish-like support 14 and
is heated to an effectively high temperature by direct radiation
from the heating element or elements 22.
[0047] In a modification of the heater 2 of FIG. 9, as shown in
FIG. 10, at least one apertured member 40, such as of woven glass
or ceramic fibre or filament material and/or wire mesh material,
is additionally provided overlying the catalyst means 28 at the
front face of the heater. Such apertured member(s) 40 must of course
be permeable to smoke and/or fumes from the oven cavity.
[0048] A further embodiment of the heater 2 is illustrated in FIG.
11. The heater 2 of FIG. 11 is similar to that of FIG. 3 or FIG.
5, with the significant difference that, instead of the catalyst
means 28 being provided in the aperture through the base 16 of the
dish-like support 14 (or indeed through the peripheral wall 18 of
the dish-like support 14 as shown in FIG. 8), the catalyst means
is arranged as a coating of catalyst material on the surface of
at least part of the heating element or elements 22. In particular,
where part of the heating element or elements 22 traverses the aperture
26 through the base 16 of the dish-like support 14, as shown in
FIG. 5, the catalyst means 28 may be substantially confined to the
surface of that part of the heating element or elements 22 overlying
the aperture 26. |