Abstrict
An electric heater is described. The heater is composed of a plastic
or a rubber strip conductor with a heat resistant and electric conductive
chemical dispersed therethrough and electric conductors disposed
on either side of the strip conductor so that when the electric
conductors are coupled to a source of electrical energy current
will flow through the strip and generate heat. The strip conductor
then is covered with a polyethylene layer which is adhered thereto,
and the polyethylene layer in turn is covered by a PVC layer.
Claims
We claim:
1. An electric heater comprising:
a bendable, strip conductor of a material selected from the group
consisting of plastic or rubber and having an electric conductive
and heat resistant chemical additive dispersed therethrough;
first and second electrical conductive means attached, respectively,
to opposite sides of said strip conductor and adapter to be coupled
to a source of electrical energy so that current will flow through
said first means and through said strip to said second means to
complete a circuit and thereby cause said strips to be heated;
a polyethylene layer adhering to and covering said strip; and
a PVC layer covering said polyethylene layer whereby heat generated
in said strip will be emitted through said layers.
Description BACKGROUND OF THE INVENTION
This invention relates to structure of electric heater. Conventionally,
an electric heater completed with a temperature controller is built
in an electric blanket, electric pad, or the like. The temperature
controller is preset at a certain level to maintain temperature
of the electric heater. Generally, there are two types of electric
heater: Nickel-chrome wire, which can generate high heat during
passing of electric current therethrough; and carbon fiber. Defects
exist on both types. The first type has the following defects: (1)
It is hard, it could be broken easily during assembly or moving;
(2) It is not flexible and it should not be kept in touch with human
body directly; (3) Its external layer would break and cause electric
leakage or scalding; (4) It is not elastic and bending is difficult;
(5) Heating is not even, even heating would cause overheat or burning
of the heater itself; (6) Possibility of breakdown is high, and
(7) It does not have nice appearance.
The second type involves complicated production process and high
production cost.
In view of the above defects, the inventor created a new structure
for electric heater characterized by:
(1) Its length can be increased to meet different requirements.
(2) It has good heat conductivity, even heat conductivity and permits
adequate bending;
(3) it has good insulation property which eliminates the possiblity
of electric leakage:
(4) It does not oxidize easily;
(5) It will not be affected by small vibration;
(6) It will not burn or breakdown during operation;
(7) It is flexible and provides sense of comfort while it is kept
in touch with human body; and
(8) It has a nice appearance.
SUMMARY OF THE INVENTION
The present invention provide a new structure of electric heater
composed of a plastic/rubber conductor made of plastics/rubber with
heat resistant and electric conductive chemical additive, two conductors
at ends of the conductor, a polyethylene cover adhered by means
of thermal welding process, and an uppermost PVC layer. It is heat
conductive, electric insulated, soft and flexible PVC outermost
layer. The present invention is completed with a temperature controller
and a power switch for safe and reliable operation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a preferred embodiment according
to the present invention.
FIG. 2 is a perspective view illustrating an application of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a sectional view of a preferred embodiment according
to the present invention. As shown in the drawing, it is a strip
or sheet composed of plastics or rubber and heat resistant/electric
conductive chemical formed by extrusion. Extruded strip or sheet
is cut to appropriate size to form plastic conductor (1). Each end
of a plastic conductor (1) is adhered with a conductor (2 or 2')
by means of conductive gel so that power can be conducted from the
conductor (2) through the plastic conductor (1) to another conductor
(2'). Because the plastic conductor (1) has a certain internal resistance,
flowing of current through it will generate a certain heat energy.
In order to emit heat energy from the plastic conductor safely and
to provide an appropriate flexibility, the plastic conductor (1)
is covered with polyethylene (3) by means of thermal welding. It
will also protect the conductors (2 and 2') from loosening. Since
polyethylene (3) has good heat conductivity and electric insulation,
covering of polyethylene (3) on the plastic conductor (1) will prevent
from breaking due to bending and maintain good theremal conductivity.
Heat resistant and soft PVC is further covering the polyethylene
(3) on the plastic conductor (1). PVC is soft, and of good heat
conductive, it gives no harm to humam body and it has a nice appearance,
it is used as the outermost layer of the plastic conductor (1).
The plastic conductor (1) is covered with polyethylene (3) first
and then with with PVC (4) by means of thermal welding process.
PVC is not used to cover the plastic conductor (1) directly because
the plastic conductor (1) will be at high temperature and melting
point of PVC is lower than polyethylene. Of course, if temperature
required is not so high, PVC can be used to cover the plastic conductor
directly.
The plastic conductor (1) can be formed by compound with different
electric conductive chemical contents or different electric conductive
chemical materials to meet different temperature requirements.
FIG. 2 illustrates an application of the present invention to a
electric blanket/heater pad. It is made of a piece of plastic conductor
according to the present invention with a fabric cover to provide
warmness and comfort.
The present invention can be made in different size for different
temperature to meet different requirements by varying concentration
of electric conductive chemical. |