US2681409A - Condensate removing apparatus - Google Patents

Description

June 13,1954 J. P. DOBBINS CONDENSATE REMOVING APPARATUS 5 Sheets-Sheet 1 Filed Nov. 19, 1949 INVENTOR. JOHN P. DOES/N5 BY %%114 Afik ATTORNEY June 15, 1954 J. P. DOBBINS 2,681,409

CONDENSATE REMOVING APPARATUS Filed Nov. 19, 1949 5 Sheets-Sheet 2 IN V EN TOR. JOHN P. DOBB/NS ATTORNEY June 15, 1954 J. P. DOBBINS 2,681,409

CONDENSATE REMOVING APPARATUS Filed Nov. 19, 1949 3 Sheets-Sheet 3 F/G INVENTOR.

JOHN P. DOBB/NS ATTORNEY Patented June 15, 1954 CONDENSATE REMOVING APPARATUS John P. Dobbins, Los Angeles, Calif., assignor to North American Aviation, Inc.

Application November 19, 1949, Serial No. 128,383

1 Claim. 1

This invention pertain to an arrangement for removing ice or other aqueous condensates from various parts of vehicles such as aircraft, and for preventing their collection or formation on such parts.

In the past attempts have been made to use radiant heat sources for these purposes, but it has been found that the forms of apparatus previously used are incapable of supplying energy that will accomplish the purpose. More particularly it has been found that the spectral distribution of the radiation emitted by the systems used in the past corresponds with temperatures which are too low for adequate radiant transmission through filters used for obstructing visible light. Also, the output intensities of such systems are insumcient to meet the heat delivery requirements for ice removal in severe weather conditions.

Efforts have been made to deice Windshields by the use of radiant-heater apparatus constituting virtually a heater rather than apparatus that effectively applies radiation in the infrared and near-visible range according to the present invention. Emitters such a Calrod heating elements, manufactured by the General Electric Company, or Chromalox rods, manufactured by the Montgomery Bros. Manufacturing Company, have been proposed for such use but have been found to be unsatisfactory for the reason that an open face heater of a size which can be used with aircraft Windshields cannot deliver sufiicient heat at the front surface of the receiving panel under known flight conditions to provide from 1,000 to 2,000 B. t. u. per square foot per hour, without giving off radiation in the visible range. Any attempt to filter out visible light in an arrangement such as this by means of ruby glass resulted in either a heating source which was too large and cumbersome to be included in aircraft cockpits, or did not have suificient energy output to obtain the intended purpose. A compact source that will accomplish the intended purpose is referred to herein as a high-intensity source.

It has also been proposed, prior to this invention, to provide a surface with an electrically conductive coating for delivery of deicing heat. This arrangement has not proved satisfactory for several reasons, and particularly because of difficulties encountered in supplying heat uniformly to curved or non-rectangular shaped areas such as are commonly encountered in aircraft windshields.

Applicant has solved the problem of obtaining sumcient radiation tomeet the deicing requirements by the use of an incandescent lamp of special construction which emits a preponderance of radiation in the near visible range to thereby provide a compact unit such as can be included in an aircraft cockpit, but at the same time one which will satisfactorily obtain the desired deicing results. Such a lamp is particularly usable with a novel filter arrangement which readily transmits long-wave and near-visible radiation but which filters out visible radiation. This filter may also be used with bare wire or rod-type heating elements in small compact sizes to accomplish the purpose of the invention.

Accordingly, it is an object of this invention to provide an arrangement which can be located in the interior of an insulating structure but which will satisfactorily deice the exterior of such structure.

t is a further object of this invention to provide a windshield deicing arrangement which utilizes short, high-intensity waves, but which is not accompanied by visible light such as would be objectionable in an aircraft cockpit.

It is yet another object of this invention to provide a method of heating transparent and diathermanous panels on aircraft to prevent collection of ice thereon and to remove ice or fog formations therefrom.

It is still another object of this invention to provide an arrangement which will satisfactorily deice radomes of radar units without interfering with the operation of the radar.

It is still another object of this invention to provide a new and novel arrangement for emitting radiant energy that will satisfactorily deice windshields and yet not provide visible light.

Other objects of invention will become apparent from the following description taken in connection with the accompanying drawings, in which -Fig. 1 is a perspective View of an airplane involving the invention;

Fig. 2 is a sectional View, through the windshield, of the invention;

Fig. 3 is a cross-sectional view through a lamp arrangement forming part of the invention;

Fig. 4 is a sectional view of the lamp, reflector, and filter assembly, illustrated in Fig. 3;

Fig. 5 is a cross-sectional view of a modified form of radiant heat source;

Fig. 6 is a sectional view through a radome unit in which the invention is incorporated;

Figs. 7, 8, and 9 are sectional views of modified lamp arrangements;

Fig. 10 is a sectional view along lines l0--i0 of Figs. 7, 8, and 9; and

Fig. 11 is a cross-sectional view through a lamp having a modified reflector arrangement.

Referring to the drawings, Fig. 1 represents an airplane, such as a night fighter, equipped with a windshield 2, and a radome unit 3 for enclosing radar equipment, to which the invention may be applied.

Referring generally to Fig. 2 there is illustrated a windshield element suitably carried by frame and with which is associated heat source 6. Each of these heat sources is formed of a reflector T in which is mounted a lamp 8 of incandescent types comprising a transparent quartz envelope filled with inert gas and in which is located a suitable filament 9. Associated with the reflector 1 is a filter member it of ruby glass or the like for filtering out any visible light transmitted through the quartz glass 8. The ruby glass is used in sections of approximately 3 5 thick and in one form is known as the No. 2540 Corning infrared filter. The beam spread of the lamp is illustrated by dotted lines.

This combination provides a satisfactory deicing arrangement wherein the high temperature of the lamp results in the production of long and short wave-lengths, most of which pass through the ruby glass. However, since ruby glass transmits radiation in the near-visible range, it is particularly adaptable for use with a lamp source. It does not, however, transmit radiation in the visible range or in the infrared range beyond about five microns. The quartz glass of the lamp is highly desirable because, compared with other glass compositions, it is more transmissive of long-wave radiation. Further, the quartz glass withstands higher temperatures than other forms of vitreous material used for this purpose. Since visible light is of shorter wave-length than one micron, and varies from approximately 0.4 to 0.8 of a micron, short-wave radiation, in the sense used in this disclosure, refers to that which has a wave-length of less than approximately one micron, whereas long-wave radiation is that which has a wave-length greater than approxh mately one micron.

In a modified form of the invention, as shown in Fig. 5,. a filament H is associated with a refiector l2 and a filter l3 of crystalline silver chloride. The filter is formed by cooling down slowly a mass of molten silver chloride to produce a single crystal. This results in a relatively large crystal from which sheets may be out which are passed through metal rolls. The resulting sheets of material may be dipped in an alkaline-sulfide bath, thereupon producing a shiny black surface of silver sulfide (AgzS) in accordance with the technique disclosed in the Journal of the Optical Company of America, volume 37, No. 5, page 340, May, 1 -17, by Dr. H. C. Kremers, in which the sheet is coated for the purpose of protecting the sheet from damage which may be occasioned by the passage therelnto of ultra-violet and short-wave visible light. This particular subject matter is also disclosed in U. S. Patents No. 2,l20,955 and No. 2,420,956, issued May 20, 1947 to Harry C. Kremers. The sheet material may be dipped and rerolled until it is opacified to a satisfactory degree or to a degree wherein visible light will be filtered out to where less than one percent passes there through. The transmitted infrared rays, however, are not appreciably diminished in. intensity by the coating. This arrangement is highly chicient for the reason that the visible portion of the spectrum is selectively reflected and absorbed by the coating on the sheet, whereas wave-lengths in the infrared and near-visible range are transmitted. Light does not photochemically affect the silver chloride when the latter is coated with silver sulfide and, accordingly, the material will not darken when used or exposed to light for long periods of time. Multiple-crystal silver chloride may be used instead of the single-crystal form, although it is not quite so efficient in the transmission of the long-wave radiation.

Other materials than silver chloride will function satisfactorily for the intended purpose, these including other halides of silver as well as those of lead, gold, or other suitable heavy-metal salts capable of transmitting long-wave radiation. Desirable characteristics of such materials are that they have good forming, weathering, temperature, and stability characteristics. The material also must be capable of being coated readily so as to prevent transmission of visible radiation. In addition to the sulfides coated on the halide bases, selenides and tellurides may be used on such bases, or metallic selenium may be deposited as a thin film on the surfaces of the sheets for preventing transmission of visible radiation. Gilsonite coatings, or even elementary sulfur or tellurium may also be used in lieu of selenium.

Referring now to the arrangement in Fig. 6, a high-intensity radiant source 21 of either the external reflector type units illustrated in Figs. 3-5, or the internal reflector type units illustrated in Figs. 7-11, but circular in shape, is placed at the circumference of a radar scanning unit l5. This arrangement avoids any interference with the operation of the radar scanning unit while at the same time effectively deices the radome structure i6. If desired, the radar scanning unit itself may be the emitter of thermal radiation to the radome unit. Heat supplied to the scanning unit may be in the form of electrical energy dissipated through resistance units.

Referring to Figs. '7, 8, 9, l0, and 11, there are illustrated lamps of the incandescent type having glass portion ll, filament iii, reflector l9, end supports 2%), and supporting disks 2|. Rod members 22 and 22a are slidably supported in disk members 2! and adapted to be connected to supports 20 by Wire elements 23 or the like. Filament It may be supported by wire 28 and projection 29 as typically illustrated in Figs. '7 and 10. Conductor elements 24 are adapted to be connected to a suitable source of power. In the arrangement illustrated in Fig. 7 the conductor elements 24 are on opposite sides and ends of the tube, whereas in Fig. 8 conductor elements 24 are on the same end. In Fig. 9 the conductor elements 24 are on opposite sides of the tube but the filament i8 is supported at one end by a conducting member 14 carried by two of bars 22 but out of contact, and at the other end by spring member 25. An additional reflector 25 may be used as illustrated in Fig. 11 if desired to limit the angular divergence of the beam.

In one form of construction, to solve the requirements of a particular airplane, it has been discovered that the envelope of the lamp is formed of glass tubing fabricated from Corning No. 2560 series material, using particularly No. 2562 glass which has an annealing point of 565 C. and a strain point of 531 C. A wall thickness of about a -inch has been found to be satisfactory. The inside surface of the envelope is coated over an angle of approximately 210? of are along a length of about 25 inches with metallie silver or gold. This construction obtains an operating temperature of the front glass surface of 500 C. and a temperature on the rear surface of approximately 450 C. The envelope contains a gas composed of approximately 95% argon or krypton-the balance, nitrogen. During full-power operation an internal gas pressure of approximately 450 mm. of mercury is obtained. A filament of drawn tungsten wire is used and is located approximately 0.17 inch from the reflec tor surface, and symmetrically disposed thereto. The heating element comprises a single 25-inch coil filament wound at A;-inch average diameter to give 220 total turns. The diameter of the filament is approximately 1.35 mm. and 220 cm. in length. The over-all length of this lamp will be approximately 30 inches, With a diameter of about one inch, and will operate at 28 volts with an input of about 1,000 watts. This will satisfactorily deice an area of windshield approximately 8 in. x 30 in.

A lamp source of radiant energy for purposes of the invention is more effective, when used for heating plastic Windshields or enclosures, than the low-temperature open wire type source, for the reason that the shorter wavelengths emitted by the lamp are better transmitted through the plastic material to heat it throughout, together with any condensate which may appear on the exterior thereof; whereas the low-temperature type, emitting long-wave radiation, must necessarily heat the near surface of the material, which material is then heated throughout its thickness by conduction. This would require a greater amount of energy to accomplish the desired objective with thick sheets, and is accompanied by a greater danger of cracking the glass when used to deice that type of windshield.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and. scope of this invention being limited only by the terms of the ap pended claim.

I claim:

A device for de-icing the remote side of a nonmetallic panel comprising an elongated hightemperature short wave infrared radiation-pro ducing filament; an elongated sealed quartz glass tubular envelope having a non-oxidizing interior atmosphere disposed in surrounding relationship with said filament for transmitting the radiation produced thereby; means disposed between said envelope and a non-metallic panel for filtering the visible spectral components from said radiation; and means closely associated with said envelope for reflecting said radiation through said filter means and against said panel, whereby said radiation passes through said panel for re moving ice and condensate on the surface thereof remote from said device.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,032,267 Bastian July 9, 1912 1,852,599 Zaiger et a1. Apr. 5, 1932 1,917,141 Middleton July 4, 1933 2,317,019 Altemus Apr. 20, 1943 2,319,912 Anderson et a1 May 25, 1943 2,375,369 Knight et al May 8, 1945 2,408,867 McCollum Oct. 8, 1946 2,414,520 Greenwald nnnnnn Jan. 21, 1947 2,424,454 Gordon July 22, 1947 2,438,972 Hoffman Apr. 6, 1948

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