Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF, AND APPARATUS
FOR, DE-ICING AN AIRCRAFT
BY INFRARED RADIATION
Technical Field
This invention relates generally to the field of methods of, and apparatae for,
de-icing portions of an aircraft on the ground, and, more particularly, to an improved method
and apparatus for de-icing an aircraft by means of a focusable, variable-wavelength infrared
energy source.
Back~round Art
It is sometimes necessary to de-ice then anti-ice certain portions of an aircraft prior
to take-off.
Fxi.~ting technology in common use today involves the spraying of large quantities
of chemicals onto the working surfaces (e.g., wings, rudder, ailerons, flaps, stabilizers, etc.)
of the aircraft. These chemicals are normally applied just prior to the aircraft's departure from
the boarding gate. Federal re~luirclllelll~ dictate a m~ximllm time interval between application
of the anti-icing spray and take-off. This time interval is usually on the order of from about
fifteen to about thirty minutes. Ullrollullately, with the traffic jams common at some major
airports, the departure interval is often exten~ed beyond that recomm~n-1ed. If this occurs, the
plane must sometimf ~ be de-iced and anti-iced a second time before take-off. The desire to
m~int~in established schedules and to ",il~i",i~e costs makes this second step undesirable, even
if needed. The presence of ice and snow on airfoil surfaces during take-off has been indicated
as the probable cause of many crashes.
The foregoing, when considered along with soon-to-be-enforced stricter
envilol~ l regulations concerning the h~n-lling, storage, use and collection of over-sprayed
de-icing and anti-icing chemicals, establishes a present need to find a better way to remove
~cl-ml-l~tions of ice and snow in preparation for take-off.
Two types of de-icing and anti-icing chemicals are
in use today. The United States typically uses Type I, which
is a mixture of ethylene glycol or propylene glycol and water.
This mixture is heated to about 140-180~F, and then sprayed on
the aircraft. European countries commonly use Type II. This
is a blend of glycol and a thickening agent, which creates a
thicker jelly-like substance. The Type II mixture does hold
longer, but can effect take-off of small aircraft. Hence, it
is not recommended for use on aircraft having rotation speeds
of less than about 85 knots.
It has been proposed that all U.S. airport de-icing
and anti-icing equipment be modified to use European Type II
chemicals. However this has shortcomings. Upon information
and belief, propylene glycol is considered safe to humans by
the Food and Drug Administration, but is harmful to the
environment. While not currently regulated by OSHA, it has
been reported to cause skin irritation, and is listed as a
hazardous air pollutant in the Clean Air Act Amendments of
1990. Ethylene glycol is poisonous to humans, and is
regulated by OSHA because of a risk of throat and respiratory
tract irritation. The Water Quality Act of 1987 prohibits the
discharge of polluted water into navigable waters and
regulations have been promulgated to prevent airports from
dumping or discharging glycol-contaminated storm water run-off
into rivers and sewer systems.
Accordingly, there is believed to be a clear and
present need for an improved method of, and apparatus for, de-
icing portions of an aircraft without the need of such de-
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icing chemicals.
Disclosure of the Invention
According to one aspect, the present invention
provides a method of de-icing a portion of an object,
comprising: (a) providing a structure having a source of
infrared radiation, said source including a first means for
emitting infrared radiation of a first wavelength and a second
means spaced from said first means and heated by the infrared
radiation emitted by said first means for emitting infrared
radiation of a second, predetermined wavelength; (b) moving an
object relative to said structure to a position adjacent to
said source of infrared radiation; (c) operating said source
of infrared radiation so as to emit infrared radiation of said
second wavelength toward the portion of said object to be de-
iced; and (d) adjusting the spacing between the first means
and the second means, thus controlling the distribution of
infrared radiation emitted at the second wavelength so as to
concentrate such radiation on any snow and ice to be melted
from said object portion; (e) thereby to provide radiant
infrared energy at a high concentration and at a desired
wavelength to melt the snow and ice from said object portion.
According to another aspect, the present invention
provides a method of heating a portion of an object,
comprising: (a) providing a structure having an infrared
heater, a first means for emitting infrared radiation of a
first wavelength, and a second means spaced from said first
means and heated by the infrared radiation emitted by said
first means for emitting infrared radiation of a second
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wavelength; (b) moving an object relative to said structure to
a position adjacent to said heater; (c) operating said heater
so as to emit infrared radiation of said second wavelength
toward the position of said object to be heated; and
(d) adjusting the spacing between the first means and the
second means, thus controlling the distribution of infrared
radiation emitted at the second wavelength so as to maximize
the absorption of such radiation by said object portion;
thereby to heat said object portion.
According to yet another aspect, the present
invention provides apparatus for emitting infrared radiation
of a desired wavelength toward an object, comprising: (a) a
primary surface; (b) a heater for raising the temperature of
said primary surface so as to cause said primary surface to
emit infrared radiation of a first wavelength; (c) a secondary
surface surrounding said primary surface in spaced relation
thereto and arranged to be heated by infrared radiation
emitted by said primary surface and for emitting infrared
radiation of a second wavelength toward said object; and (d)
an actuator for selectively varying the spacing between said
primary and secondary surfaces so that infrared radiation
emitted by said secondary surface at the second wavelength
will be focused; (e) whereby said apparatus will emit infrared
radiation of a desired wavelength toward said object.
According to still another, the present invention
provides apparatus for emitting infrared radiation of a
desired wavelength toward an object, comprising: (a) a heat
source; (b) a first heat exchanger substantially surrounding
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the heat source, shaped and positioned relative to the heat
source so as to radiate heat at a first wavelength when the
heat source operates at a predefined temperature; and (c) a
second heat exchanger substantially surrounding the first heat
exchanger, shaped to radiate heat at a second wavelength when
the heat source operates at a predefined temperature.
According to a further aspect, the present invention
provides a method of de-icing an object comprising: (a)
providing a structure having a heat source, a first heat
exchanger spaced from the heat source, and a second heat
exchanger spaced from the first surface; (b) positioning an
object relative to said structure; and (c) operating the heat
source at a temperature that heats the first heat exchanger
and causes the first heat exchanger to radiate infrared
radiation at a first wavelength in the direction of the second
heat exchanger, thereby causing the second heat exchanger to
radiate infrared radiation at a second, desired wavelength
toward the object.
Accordingly, the general object of the invention is
to provide an improved method of de-icing portions of an
aircraft prior to take-off.
Another object is to provide improved two stage heat
exchanger for de-icing portions of an aircraft prior to take-
off.
Another object is to provide an improved method of,
and apparatus for, de-icing portions of an aircraft by a
radiant infrared technique, and by avoiding the use of
potentially hazardous de-icing chemical in common use today.
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Still another object is to provide an improved
method of, and apparatus for, heating a distant object by
means of emitted infrared radiation.
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21360S6
These and other objects will become apl)alenl from the foregoing and ongoing
written specification, the drawings, and the appended claims.
Brief Description of the Drawin~s
Fig. 1 is a flow chart of a preferred sequence of manipulative steps involved in
S practicing the improved method to de-ice an aircraft.
Fig. 2 is a top plan view of a drive-through structure containing a plurality of
infrared heaters, with the roof of the structure removed, and showing the array of heaters
relative to two aircraft positions.
Fig. 3 is the front elevational view of the drive-through structure shown in Fig. 2.
Fig. 4 is a fr~gm~nt~ry vertical sectional view of one of the heaters, showing the
surrounding skirt as being in one position relative to the burner.
Fig. 5 is a fragmentary vertical sectional view of one of the heaters, showing the
surrounding skirt in another position relative to the burner.
Description of the Preferred Embodiment(s)
At the outset, it should be clearly understood that like reference numerals are
intended to identify the same structural elements, portions or surfaces consistently throughout
the several drawing figures, as such elements, portions or surfaces may be further described or
explained by the entire written specification of which this detailed description is an integral part.
Unless otherwise indicated, the drawings are intended to be read (e.g., arrangement of parts,
20 mounting, etc.) together with the specification, and are to be considered a portion of the entire
written description of this invention. As used in the following description, the terms
"horizontal," "vertical," "left," "right," "up" and "down," as well as adjectival and adverbial
derivatives thereof (e.g., "horizontally," "rightwardly," "uL ~dldly," etc.) simply refer to the
orientation of the illustrated structure as the particular drawing figure faces the reader. Unless
otherwise indicated, the terms "inwardly" and "outwardly"
refer to the orientation of a surface relative to its axis of
elongation, or axis or rotation, as appropriate.
Turning now to the drawings, the present invention
provides an improved method of, and apparatus for, heating a
substance by means of emitted infrared radiation. In one
application, the method and apparatus are used to de-ice an
aircraft.
Referring now to Figs. 1-3, an aircraft to be de-
iced is driven through an open-minded structure, generally
indicated at 10, having a plurality of overhead infrared
heaters, severally indicated at 11 arranged in a rectangular
array. In Fig. 2, two aircraft positions are indicated within
the structure. The first is indicated at 12, and the second
is indicated at 13. These two positions have been omitted
from Fig. 3 in the interest of clarity.
As best shown in Fig. 1, the aircraft first enters
the drive-through de-icing structure 10, as indicated at block
14 in Fig. 1. Upon entry to that structure and/or when in the
position of aircraft 12, as much ice, snow and/or water as can
be removed are physically removed. This is indicated in block
15 in Fig. 1. The means for physical removal may include an
air curtain, or the like. After as much of the adherent
substance as can be physically removed has been removed, the
aircraft then advanced forwardly toward the second station,
indicated by aircraft position 13. This step is indicated in
block 16 of Fig. 1. Assuming that the type of aircraft is
known, selected heaters are then operated to emit radiation.
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The particular heaters which may be operated may be determined
either from the known type of the aircraft (i.e. having a
known shape), or by proximity sensors (not shown) acting
downwardly and operatively arranged to sense portions of the
aircraft therebeneath. This latter step is indicated by block
18 in Fig. 1. In any event, only those heaters which are
aimed downwardly at portions of the aircraft are operated.
Those heaters which are operated are selectively focused to
emit radiation to maximize energy on the surface of the
aircraft as needed to melt ice or snow. This is indicated by
blocks 19 and 20 in Fig. 1. The various heaters emit
radiation toward the aircraft at a wavelength which coincides
with the wavelength of the maximum absorptivity of the
substance to be removed. In any event, after the adherent
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substances have been melted, the aircraft is then dried, as indicated in block 21 of Fig. 1. The
aircraft may be dried under the influence of heat with or without an acco~ allying air curtain.
Thereafter, anti-icing chemicals are applied to the now-dry aircraft (as indicated at 22 in
Fig. 1), and the aircraft then exits the de-icing structure (as indicated at 23 of Fig. 1), taxis to
5 the runway, and is ready for take-off.
Fig. 4 is a fr~gmf nt~ry vertical sectional view of one of the heaters shown in
Figs. 2 and 3. This heater al,pàl~lus, generally indicated at 11, broadly includes a burner 24
operatively arranged to heat a frusto-conical primary surface 25, a secondary surface 26
surrounding the primary surface in spaced relation thereto, and an actuator 28 operatively
10 arranged to selectively vary the spacing between the primary and secondary surfaces. The
heater or burner 24 is shown is including a control housing 29 having a downwardly-directed
burner head 30 arranged concentrically within an elongated vertical tube 31. Thus, a flame
emitted by burner 24 will travel down the tube and be discharged through the lower open
end 32 thereof toward a dish-like layer of in.sul~ti~n 33 arranged on the upper side of a wall 34.
15 The heat of combustion will then heat primary surface 25, and will flow upwardly through the
annular space between inner tube 31 and outer tube 35, and be vented through a lateral
opening 36. The secondary surface 26 is shown as being frusto-conical in shape, and has a
downwardly-facing annular horizontal portion 38 at its upper end. The entire secondary
surface 26, 38 is insulated, as indicated at 39. Actuator 28 has a body or housing 40 mounted
20 on the control housing, and has a rod portion 41 connected to the insulated secondary surface.
Actuator 28 may be selectively operated to move rod 41 either upwardly or downwardly, as
desired. Such operation of the actuator effectively varies the spacing between the primary and
secondary surfaces, and changes the output concentration and focal distance.
In operation, a conventional gaseous fuel is supplied to the burner, and is ignited.
25 The burner then issues a downwardly-directed flame against insulation 33. The flame then rolls
reversely and rises upwardly to heat primary surface 25. The heat of combustion travels
upwardly through the annular chamber between the inner and outer tubes 31, 35, and is then
vented via lateral opening 36. Thus, the heater raises the
temperature of the primary surface 25, and causes it to emit
infrared radiation. The temperature of the primary surface
may be on the order of 2000~F. The infrared radiation emitted
by the primary surface is directed toward the secondary
surface and raises its temperature. The temperature of the
secondary surface 26 is, therefore, less than that of the
primary surface, and may typically be in the range of about
900-1000~F. The secondary surface then emits infrared
radiation of a desired wavelength downwardly toward the
aircraft therebeneath. Thus, the primary surface radiates
infrared energy to heat the secondary surface, which in turn
emits radiation toward the object.
One unique feature of the invention is that the
actuator 28 is selectively operated so as to vary the spacing
between the primary and secondary surfaces so that the
secondary surface will emit infrared radiation of a desired
energy pattern.
In the preferred embodiment, the desired wavelength
is the wavelength of the maximum absorptivity of the material-
to-be-removed (e.g., ice, snow or water). Thus, the apparatus
may be tuned to emit radiation at the desired wavelength by
selectively varying the design between the primary and
secondary surfaces.
Fig. 4 depicts the depending cup-shaped skirt having
the secondary surface as being in one position relative to the
burner, and Fig. 5 simply depicts such skirt as being in a
lowered position relative to the body. This is simply to
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illustrate the difference in spacing between the primary and
secondary surfaces.
Modifications
The present invention contemplates that many changes
and modifications may be made. While it is presently
preferred to use the apparatus to selective de-ice aircraft,
the person skilled in this art will readily appreciate that
the improved method and apparatus could, alternatively, be
used to simply heat an object. Accordingly, this alternative
use should not be excluded from the scope of the claims unless
an express limitation to the effect appears therein.
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The improved method may include a greater or lesser number of steps than those
shown in Fig. 1. Similarly, the structure of the apparatus may differ from that shown in
Figs. 4 and 5. For example, the primary surface 25 need not be frusto-conical, but could be
convex or arcuate, as desired. Similarly, the outer tube 35 could be tapered upwardly so as to
5 provide a progressive flow restriction, all with the concomitant advantage of also heating outer
tube 35. Similarly, the inverted cup-shaped skirt which forms the body of the secondary
surface need not be of the particular form and shape shown. In other words, the secondary
surface could be arcuate, parabolic, or some other concave surface, as desired.
Therefore, while preferred forms of the improved method and apparatus have been
10 shown and described, and several modifications thereof discussed, persons skilled in this art will
readily appreciate that various additional changes and modifications may be made without
departing from the spirit of the invention, as defined and ~lirrelellliated by the following claims.
