Abstrict
Disclosed is a far-infrared electric heater mainly including an
electric heating coil, an inner element set in the heating coil,
and an outer tubular member enclosing and insulating the heating
coil and the inner element. The inner element is made by mixing
and sintering quartz and far-infrared optical material. Continuous
teeth are provided on outer surface of the inner element and/or
inner surface of the outer tubular member to increase surface area
for enhancing the reflection of the radiant far-infrared rays, so
that an object can be heated by the electric heater in a highly
efficient manner.
Claims
What is claimed is:
1. A far-infrared electric heater comprising an inner element,
an electric heating coil, and an outer tubular member for supporting
and insulating said electric heating coil; said inner element being
formed by mixing and sintering quartz and far-infrared optical material,
said inner element being contained within said electric heating
coil; said electric heating coil radiating far-infrared rays when
it is supplied with a current and heated; and an outer circumferential
surface of said inner element and an inner circumferential surface
of said outer tubular member being provided with a plurality of
continuous teeth, whereby said far-infrared electric heater has
increased surface area to reflect far-infrared rays radiated by
said electric heating coil to an object to be heated and thereby
provides enhanced working efficiency.
2. The far-infrared electric heater as claimed in claim 1, wherein
said inner element is a tubular member.
3. The far-infrared electric heater as claimed in claim 1, wherein
said inner element is a bar-like member.
Description BACKGROUND OF THE INVENTION
The present invention relates to an improved far-infrared electric
heater, and more particularly to a far-infrared electric heater
including an electric heating coil wound about an inner element
formed from sintered quartz and far-infrared optical material and
then covered with an outer tube. An inner surface of the outer tube
and/or an outer surface of the inner element can be provided with
continuous teeth to achieve optimal heating effect.
It has been known that far-infrared heaters are widely employed
in general domestic appliances, such as electric ovens, radiant
heaters, microwave ovens, etc. The employment of far-infrared heaters
can generally have the advantages of fast and even heating, lower
consumption of energy, and superior heating effect. FIGS. 1 and
2 illustrate a conventional far-infrared heater that has been currently
widely used in an electric oven. As shown, the far-infrared heater
includes an electric heating coil 1 set in an outer tube 2 which
serves as a supporter and insulator for the heating coil 1. Generally,
the outer tube 2 is made of high-temperature resistant and insulating
materials, such as quartz, ceramic enamel, or other ceramic materials.
Moreover, far-infrared optical paint 3 is sprayed over circumferential
surface of the outer tube 2. The electric heating coil 1 spirally
extends with two ends thereof connected to a power source. When
the heating coil 1 is supplied with a current and heated, it produces
radiant energy which passes the far-infrared optical paint 3 over
the circumferential surface of the outer tube 2 and is refracted
to produce far-infrared sources. The produced far-infrared rays
are further reflected by an aluminum-plated inner case of the electric
oven in which the far-infrared heater is installed, so that food
in the electric oven is subjected to the far-infrared rays from
different directions in the oven and can be evenly heated and cooked
within a shortened time.
Generally, there are three ways to combine the far-infrared optical
paint 3 with the outer tube 2: 1) the far-infrared optical paint
is sprayed over the circumferential surface of a quartz tube, 2)
the far-infrared optical paint is sprayed over the circumferential
surface of a ceramic enamel tube, and 3) the far-infrared optical
paint is mixed with ceramic powder and the mixture is sintered to
form the outer tube 2. However, following problems with the outer
tube 2 formed from these three ways can be found from long-term
observation over the use of such outer tube 2 in the conventional
far-infrared heater:
A. For a quartz tube sprayed with far-infrared optical paint:
a. The sprayed far-infrared optical paint tends to be scraped off
during transportation or assembling and makes the quartz tube looking
ugly;
b. The sprayed far-infrared optical paint tends to peel off when
the quartz tube is heated at high temperature and therefore contaminates
food being cooked;
c. The far-infrared optical paint is not well pervious to light
that results in slow raising of temperature and prolonged time of
baking or roasting, as well as low working efficiency and higher
consumption of energy;
d. The far-infrared optical paint forms uneven surface on the outer
tube. Grease from the cooked food tends to attach to and cumulate
on the uneven surface and is not easily removed therefrom after
the far-infrared heater has been used for a long time. The grease-attached
far-infrared heater looks ugly and dirty, and will adversely affect
the radiation of the far-infrared rays; and
e. When the outer tube 2 is broken, the spirally extended heating
coil 1 is not supported and is easily exposed to the open air to
dangerously shock a user.
B. For a ceramic enamel tube sprayed with far-infrared optical
paint:
a. The sprayed far-infrared optical paint tends to be scraped off
during transportation or assembling and makes the ceramic enamel
tube looking ugly;
b. The sprayed far-infrared optical paint tends to peel off when
the ceramic enamel tube is heated at high temperature and therefore
contaminates food being cooked;
c. The ceramic enamel tube sprayed with the far-infrared optical
paint is even inferior in its perviousness to light than the quartz
tube and therefore has even slower raising of temperature and needs
longer time of baking or roasting. The efficiency of energy conversion
is even lower and the consumption of energy is even higher than
the quartz tube;
d. The far-infrared optical paint forms uneven surface. Grease
from the cooked food tends to attach to and cumulate on the uneven
surface and is not easily removed therefrom after the far-infrared
heater has been used for a long time. The grease-attached far-infrared
heater looks ugly and dirty, and will adversely affect the radiation
of the far-infrared rays; and
e. When the outer tube 2 is broken, the spirally extended heating
coil 1 is not supported and is easily exposed to the open air to
dangerously shock a user.
C. For a ceramic outer tube containing far-infrared optical material
through sintering:
a. Like the ceramic enamel tube, this type of ceramic tube is even
inferior in its perviousness to light than the quartz tube and therefore
has even slower raising of temperature and needs longer time of
baking or roasting. The efficiency of energy conversion is even
lower and the consumption of energy is even higher than the other
two types of outer tubes;
b. The far-infrared optical paint forms uneven surface. Grease
from the cooked food tends to attach to and cumulate on the uneven
surface and is not easily removed therefrom after the far-infrared
heater has been used for a long time. The grease-attached far-infrared
heater looks ugly and dirty, and will adversely affect the radiation
of the far-infrared rays; and
c. When the outer tube 2 is broken, the spirally extended heating
coil 1 is not supported and is easily exposed to the open air to
dangerously shock a user.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide
a far-infrared electric heater which eliminates the drawbacks existing
in the conventional far-infrared electric heaters to best extend
the function of far-infrared rays.
To achieve the above and other objects, the far-infrared electric
heater according to the present invention mainly includes a spirally
wound electric heating coil set in an outer tubular member, and
an inner element formed by sintering a mixture of quartz and far-infrared
optical material. The inner element is set in the spiral electric
heating coil and can be optionally provided at an outer surface
with continuous teeth. The outer tubular member can also be provided
at an inner surface with continuous teeth. These teeth provide increased
surface areas of the inner element and the outer tubular member
to enhance reflection of the far-infrared rays produced by the heated
electric heating coil, inner element, and the outer tubular member,
so that the far-infrared electric heater of the present invention
has largely improved working efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of these and other features and advantages
of the present invention will become apparent from a careful consideration
of the following detailed description of certain embodiments illustrated
in the accompanying drawings, wherein:
FIG. 1 is a perspective of a conventional far-infrared electric
heater;
FIG. 2 is a cross section taken on line A-A' of FIG. 1;
FIG. 3 is an exploded perspective of a far-infrared electric heater
according to the present invention;
FIG. 4 is an assembled perspective of the far-infrared electric
heater of FIG. 3;
FIG. 5 is a cross section taken on line B-B' of FIG. 4; and
FIG. 6 is a cross section similar to FIG. 5 but shows another embodiment
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Please refer to FIGS. 3 and 4 that are exploded and assembled perspectives,
respectively, of a far-infrared electric heater of the present invention.
As shown, the heater mainly includes an inner element 4, a spirally
extended electric heating coil 5, and an outer tubular member 6.
The inner element 4 can be formed from, for example, a tubular
member coated with far-infrared optical material or containing far-infrared
optical material through sintering and is set in the heating coil
5 so that the coil 5 spirally winds about and extends along the
inner element 4. The outer tubular member 6 is formed from any tube
made of high-temperature resistant and insulating material, such
as quartz tube, ceramic tube, or ceramic enamel tube. The heating
coil 5 with the inner element 4 set therein is then set in the outer
tubular member 6, so that the outer tubular member 6 serves as a
insulator for the heating coil 5. The outer tubular member 6 also
serves as a support means for the heating coil 5 in the event the
individual coils of the heating coil 5 soften and droop when they
are heated.
FIG. 5 shows a cross section taken on line A-A' of FIG. 4. When
the electric heater is supplied with a current, the heating coil
5 is heated to radiate far-infrared rays, and an electromagnetic
reaction is produced on the far-infrared material contained in the
inner element 4. The radiated far-infrared rays are reflected to
pass through the outer tubular member 6 and are refracted to an
object to be heated. In the course of heating the coil 5 and the
inner element 4, other visible lights, near-infrared rays, and middle-infrared
rays produced at the same time all are not blocked and can be simultaneously
radiated on the object to be heated. That is, the electric heater
according to the present invention may have upgraded working efficiency.
FIG. 6 shows another cross sectional view of a far-infrared electric
heater according to another embodiment of the present invention.
As shown, the inner element 4 and the outer tubular member 6 are
provided at outer wall and inner wall, respectively, with a plurality
of continuous teeth, so that a toothed outer surface 41 and a toothed
inner surface 61 are formed on the inner element and the outer tubular
member 4 and 6, respectively. The toothed outer surface 41 and the
toothed inner surface 61 provide largely increased surface areas
with high refraction ratio and accordingly enable the electric heater
of the present invention to have even more excellent function of
providing far-infrared rays.
The inner element 4 coated with far-infrared optical material or
containing far-infrared optical material through sintering is not
necessarily a tubular member. The inner element 4 can be a solid
bar or of any other shape that is suitable for set in the spirally
extended coil 5.
In accordance with one aspect of the present invention, the outer
tubular member 6 is formed from a tube containing far-infrared optical
material and quartz through sintering to posses the function of
producing far-infrared rays. Advantages of such outer tubular member
6 include low manufacturing cost, high energy conversion efficiency,
easy to clean, etc. No grease will cumulate on outer surface of
the outer tubular member 6 made of sintered quartz-infrared material
to adversely affect the radiation of far-infrared rays from the
heater of the present invention.
In accordance with another aspect of the present invention, the
outer tubular member 6 is made of quartz tube and is provided with
continuous toothed inner surface 61, creating an inner wall area
that is much larger than that of a conventional tube with smooth
and round inner surface. Such toothed inner wall surface provides
increased reflective surface area and allows enhanced far-infrared
radiation.
In accordance with another aspect of the present invention, the
outer tubular member 6 is made by sintering quartz and far-infrared
optical material and is provided with continuous toothed inner surface
61. Such outer tubular member 6 not only radiates far-infrared rays,
but also provides increased reflective surface area that enables
faster raising of temperature.
In accordance with another aspect of the present invention, the
inner element 4 is in the form of a tubular member made of high-temperature
resistant and highly reflective material and serves as a supporter
of the heating coil 5 in the event the individual coils of the heating
coil 5 soften and droop when they are heated.
In accordance with another aspect of the present invention, the
inner element 4 is in the form of a solid bar made of high-temperature
resistant and highly reflective material and serves as a supporter
of the heating coil 5 in the event the individual coils of the heating
coil 5 soften and droop when they are heated.
In accordance with another aspect of the present invention, the
inner element 4, either in the form of a tubular member or a solid
bar, is coated with far-infrared optical paint to enhance the reflection
of the produced far-infrared rays.
In accordance with another aspect of the present invention, the
inner element 4, either in the form of a tubular member or a solid
bar, is made of high-temperature resistant material and far-infrared
optical material through sintering at high temperature, so that
the inner element 4 is excellent in reflecting far-infrared rays.
In accordance with another aspect of the present invention, the
inner element 4 is provided with toothed outer surface to increase
total reflective surface areas and provide enhanced reflection of
far-infrared rays.
The above-described outer tubular members and inner elements can
be freely combined to work with the heating coil.
What is to be noted is the form of the present invention shown
and disclosed is to be taken as a preferred embodiment of the invention
and that various changes in the shape, size, and arrangements of
parts may be resorted to without departing from the spirit of the
invention or the scope of the subjoined claims. |