Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Various heating devices are presently known and already in use which,
by means of an electric resistance that can be placed beneath a base plate,
provide for heating tablets containing materials, which are released by
evaporation, such as scented, deodorizing or insecticidal substances.
According to the prior art, such an electric resistance could be
wound on an insulating support of a substantially flat shape, and then coated
with an insulating enamel to produce a heating plate. However, it was
found in practice that such a heating plàte suffered from some disadvantages
during the processing step, due to the difficulty in providing a perfect
electrical insulation.
Another type of heating plate comprises a metal base plate,
provided with an electric resistance applied under said base by a metal collar
- or hooks. However7 this system has disadvantages consisting of conductivity
of the metal plate which, for safety purposes, should be connected to a
grounding jack.
The plate, which is the subject of the present invention, is
characterized by using two distinct elements, as inserted in one another, to
reali~e a throughly insulated structure of increased duration but nevertheless
more economical.
Thus, according to the invention, there is provided a heating device
for evapora~e substances, such as scents, deodorizers or insecticides,
comprising an envelope of insula~ing material, a resistance wound on a core,
such core being housed within the envelope, and two terminals of the
resistance exlting from the envelope. The envelope includes a heating
` support mounted on a body of insulating material, the two terminals of the
resistance being connected by relative plug means integral with the body for
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connection to a current tap.
Preferably, the heating support has a T-shaped cross-section and an
upper flat surface. A hole is provided at the center of the heating support,
and two extensions of the heating support each have a hole therethrough. The
inferior or stem portion of the T-shaped cross-section comprises a generally
circular shaped cross section and extends longitudinally of the support
structure to form a tubular hollow cylinder of insulating material with a flat
longitudinally extending base portion located generally tangentially to the
tubular shaped portion. A heating element comprising a small hollow cylinder
having electrical resistance wire wrapped thereabout is adapted to fit within
the tubular-shaped portion of the support member and electrical terminals
attached to the electrical resistance wires extend outwardly from the ends of -`
the tubular shaped portion. The generally flat portion of the support
member, that is the base of the T-shaped cross-section is heated by the
internal electrical resistance when current is applied to the resistance wire.
The heat causes the evaporation of a tablet which is placed thereon and
which is impregnated with an appropriate evaporative substance such as a
deodorant or insecticide.
In accordance with yet a further preferred embodiment of the
invention, the heating device as above described further includes a body for
enclosing the previously described support structure. The body is preferably
constructed of a plastic insulating material and includes a suitable means
for supporting said support structure therewithin. Further, the body lncludes
means such as a standard plug for supplying electrical current to the
resistance wires previously described which are connected thereto. The body
may then be connected to a source of electrical supply such as by inserting
the plugs into a standard wall socket or the like.
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The flat surface may be enameled with chosen colours, thereby serving
both for aesthetic and sanitary standpoints, slnce the enameled surface can be
easily and readily cleaned, without absorbing at all either the residues of
the evaporated substance or dirt.
The invention will now be described further by way of example only
and with reference to the accompanying drawings, wherein:
Fig. 1 is a perspective view showing a heating support;
Fig. 2 is a perspective view of the resistance wound up on the
cylinder of insulating material;
Fig. 3 shows the heating device ready for use;
Fig. 4 is a perspective view showing a T-shaped heating support,
having an elongated groove in the T leg, accommodating the electric resistance,
which is then cemented leaving the two terminals protruding perpendicularly
to a bigger surface of the support itself;
Fig. 5 is a cross-sectional view taken along plane V-V of Fig. 4;
Fig. 6 shows a planar heating plate of a substantial uniform
thickness, wherein the groove is formed for accommodating the electric
resistance and protecting cementing material as in Fig. 4;
Fig. 7 shows a heating plate similar to that of Fig. 6, but having
a through hole in its thickness so as to create a hole similar to that of
Fig. 1 but in which hole the electric resistance is cemented and shielded; and
Fig. 8 shows a heating plate similar to that of Fig. 7, having in
its thickness two parallel through holes with two series connected resis~ances,
the latter being also shielded, and insulated leads outwardly projecting.
As shown in Figs. 1-3, the heating support 10 comprises a T-shaped
body of insulating material having a suitable through hole 11 for accommodating
resistance 18~, composed by the small cylinder 18 on which the resistance wire
17 is wound up.
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In the cylindrical hole 11 of the heatlng support 10, there are two
diametral grooves 1~, to guide the introduction of the resistance 18' with the
associated terminals 19 and 19'. Grooves 12 are only necessary to accommodate
enlarged points of connection of terminals 19, 19' adjacent the resistance
wire 17 such as by solder beads or the like. When terminals 19, 19' extend
from the axial ends of resistance 18', no grooves are necessary. In the wall
13 which forms a tubular envelope there are moreover, two notches 14, 14' for
allowing the terminals 19, 19' of resistance wire 17 to exit from hole 11. At
the two sides of the tubular envelope 13-two extensions or enlargements 15, 15'
are provided with holes 15 " and 15 "' to prevent the heat produced by
resistance 18' to spread to the ends of the same support which is mounted in
a plastic body 40 of the electric anti-mosquito heating device. The heating
support 10 (Fig. 1) has a planar surface 16 on which the tablet containing
the evaporable substances can directly bear. This planar surface 16 is
preferably treated with a coating 16' of vitrified enamel of the desired
colour. This coating no longer performs as in the past the insulating function
for the resistance, since in this device, insulation is assured by the whole
assembly of heating support 10. The coating remàins sanitary since it cannot
become impregnated with dirt.
The heating support 10 is supported by two supporting rails 40'
` (only one shown) o~ the body 40. The rails 40' support the heating support
10 by the extensions 15 and 15'. The body 40 includes slots 41, 41' for
allowing heated air to flow through the holes 15", 15 "' so that the
substance to be evaporated is diffused by the air flow along the surface of
the heating support lO.
` Figo 2 shows a resistance wire 17 wound around a small insulating
hollow cylinder lB, having two terminals 19, 19~ to be successively connected
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directly to plugs 20 of the current tap, or through a suitable extension to the
electric current tap embedded in a wall. After winding up, said resistance
wire 17 i9 enameled with an insulating enamel 17'. The length of cylinder 18
is preferably shorter than the heating support 10. In this manner, contact
with the ends of cylinder 18 is avoided. The two terminals 19, 19' extendlng
from cylinder 18 project from the notches 14, 14' at a point displaced .
inwardly from the outward edges of the support member 10.
In Figs. 4 and 5 there is shown a heating plate 21, having a groove
22 for accommodating a resistance 23, the latter being then protected with
cement 24. In said groove 22, instead of laterally projecting, the two
terminals 25, 25' project at some distance (M) from the edge of heating
plate 21. The plate 21 has a coating 21' of vitrified enamel on one surface
thereof.
Fig. 6 shows the heating plate 21 of parallelepiped shape with
hole 22 provided therein for insertion of the resistance 23. The hole 22 is
filled with the insulating cement 24 after the resistance has been inserted.
The heating support 21 has a coating 21 " of vitrified enamel on one surface
thereof.
On the other hand, in Figs. 7 and 8 the heating plates 27 and 28
are of parallelepiped shape respectively, and therein one or two holes 27'
or 28', 28" are provided for the insertion of resistances 30 or 31 and 32,
the terminals 34, 35 and 36 of which exit through the sides of the plate.
Terminals 34, 35 and 36 are covered with thermal insulation 34', 35' and 36',
respectively. Heating plates 27 and 28 each have an enamel coating 21" ',
21 " ", respectively on their upper surface.
This approach is less complete and striking than that of Figs. 4,
5 and 6, but can be adopted should the plate be fitted on a plastic apparatus
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for protection of the two ends from which the wires exit. The top face of
each plate can be enameled to complete the features and advantages of the
device.
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