US 3830078 A
Apparatus for preventing frost from forming on cold components in a moist atmosphere. The apparatus includes: a housing to enclose the cold components on which frost is to be prevented from forming, with the housing having an inlet and an outlet; a honeycomb mesh fixedly positioned across the entire outlet; a source of cold dry nitrogen connected to the housing inlet; and valving means, between the source of nitrogen and the housing inlet, to control the flow of the cold dry nitrogen from the nitrogen source to the housing.
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Description (OCR text may contain errors)
United States Patent 1 Read  Aug. 20, 1974 ANTI-FROST APPARATUS Hottenroth 62/388 3,163,022 l2/l964 1 Inventor Wendell Read, Redondo Beach, 33353222 3513?. lliff';iiijijjiiiiiiiiij 62,388
 Assignee: The United States of America as Primar y ExammerW|ll1am J. Wye represented by the Secretary of the United States Air Force Attorney, Agent, or Firm Harry A. Herbert, Jr. Washington, DC.  Filed: July 13, 1973 57 ABSTRACT 21 A l. N 7 2 1 pp 3 9,0 8 Apparatus for preventing frost from forming on cold Related Application Data. components in a moist atmosphere. The apparatus in-  Continuation-in-part of Ser. No. 24,893, March 24, cludes: a housing to enclose the cold components on 1970. which frost is to be prevented from forming, with the housing having an inlet and an outlet; a honeycomb  US. Cl 62/282, 34/5, 34/36, mesh fixedly positioned across the entire outlet; a 62/82, 62/80, 62/78, 62/272, 62/388 source of cold dry nitrogen connected to the housing  Int. Cl. Fd 21/10 inlet; and valving means, between the source of nitro-  el O Search: 62/ gen and the housing inlet, to control the flow of the 62/78, 388; 34/5, 36 cold dry nitrogen from the nitrogen source to the p housing. 7  References Cited UNITED-STATES PATENTS 1 Claim, 1 Drawing Figure 2,343,246 3/1944 Schechter 62/80 AT WsP/VHPF 71 l3 E :5 K 44 1 ANTI-FROST APPARATUS This application is a continuation-in-part of US. Pat. application Ser. No. 24,893, filed Mar. 24, 1970.
BACKGROUND OF THE INVENTION This invention pertains to an apparatus for prevent ing frost from forming on cold components in a moist atmosphere.
In the interest of clarity and simplicity this invention will be described as adapted for use in connection with an optical sensor head operated It is to be understood that this adaptation is by way of illustration only, and not by way of any limitation.
It is well known that if the components, such as mirrors and like, of an optical sensor head are cold, and if the sensor head is used in an environment where the atmosphere is moist, then frost will form on the cold components. The result is the degrading of the performance of the entire system of which the sensor head is but a part.
My invention is a significant advance in the state-ofthe-art, since it permits the frost-free operation of cold components in a moist atmosphere.
SUMMARY OF THE INVENTION This invention pertains to and apparatus for preventing frost from forming on cold components which are in a moist atmosphere.
Therefore, the principal object of this invention is to provide an apparatus for preventing frost from forming on cold components in such an environment.
This object, and other and related ones, of this invention will become readily apparent after a consideration of the description of the invention and reference to the drawing.
DESCRIPTION OF THE DRAWING The drawing is a side elevation view, in cross-section and in schematic form, of a preferred embodiment of the invention, as adapted for a particular use.
DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawing, therein are shown: an optical sensor head having primary mirror 11, secondary mirror 12 and, disposed therebetween, detector 13; housing 20 with inlet 21 and outlet 22, enclosing sensor head components ll, 12 and I3; honeycomb mesh 30 with core cells or openings, such as 31, fixedly positioned across the entirety of outlet 22; nitrogen source 40, containing only cold dry nitrogen gas 44, and having outlet 41; and conduit-like member 42, with one end connected to housing inlet 21 and the other end connected to cold dry nitrogen source outlet 41, with valve 43 positioned to control the flow of the cold dry nitrogen gas 44 through conduit-like member 42 into housing 20.
It is to be noted that, in the embodiment shown in the drawing, honeycomb mesh 30 is of the conventional type, i.e., an array of a plurality of hexagonally shaped adjacent apertures. Additionally, it is to be remembered that nitrogen gas 44 is cold and dry and components ll, 12 and 13 are cold. Further, the atmosphere within housing 20 and external of housing 20 is moist in a moist atmosphere. I
and the flow of the cold dry nitrogen gas 44 is as indicated, when valve 43 is in an open mode.
MODE OF OPERATION OF THE PREFERRED EMBODIMENT In essence, and succinctly, the preferred embodiment is as follows: the cold dry nitrogen gas 44 in source 40 is valved and is introduced into conduit-like member 42 by positioning valve 43 in the open mode. The cold dry nitrogen gas 44 flows through conduit-like member 42, and enters housing 20 through housing inlet 21. Nitrogen gas 44, which is cold and dry, permeates and is diffused throughout the interior of housing 20, which encloses components 11, 12 and 13 which said components are to be kept frostfree, despite the presence of a moist atmosphere. Cold dry nitrogen gas 44 exits or vents from housing 20 by leading through core cells or openings, such as 31, of honeycomb mesh 30 which is fixedly positioned across housing outlet 22, and by flowing into the moist atmosphere external of housing 20. In summary, the flow of the mode of operation of the cold dry nitrogen 44 into housing 20 and out of the 30, and prevents moist air external of housing 20 from I entering the housing.
It is reiterated, and emphasized, that the flow of cold dry nitrogen gas 44 into housing 20 is continuous.
The net result of the continuous flow of cold dry nitrogen 44, and the constant exposure of cold components ll, 12 and 13 to said cold dry nitrogen gas 44, is the maintenance, frost-free, of said cold components and their permissive efficient use in the moist atmospheric environment, without degrading the performance either of any of these components or of the optical sensor head, and system, of which these components are but a part.
It is again stated that, although reference has been made to the use of this invention in connection with an optical sensor head, this is but one specific application and adaptation of the invention. The invention may be used in any situation or art where it is desired to keep cold components, particularly optical components, frost-free in a moist atmospheric environment. In connection with the adaptation of this invention in other situations and arts, as well as in the present application with the components of an optical sensor head, if there is a problem of reverse flow of the cold dry nitrogen gas due to pressure variations, however unlikely, a thin sheet of material (transparent in the case of the optical sensor head) can be placed directly in back (i.e. on the internal side) of the honeycomb mesh 30 and small holes made in the sheet of material in registration with the plurality of core cells or openings, such as 31, of the honeycomb mesh 30, to meter the flow of the cold dry nitrogen gas 44 to each core cell or opening, such as 31, in the honeycomb mesh 30. The small holes in the material allow a pressure differential to be established across the sheet of material which will prevent the reverse flow of the cold dry nitrogen gas 44.
While there has been shown and described the fundamental features of the invention, as applied to a preferred embodiment, it is to be understood that various b. a honeycomb mesh fixedly positioned across the entire outlet of said housing;
c. a source of only cold dry nitrogen gas connected to the inlet of said housing;
d. and, valving means, between said source of'only cold dry nitrogen gas and the inlet of said housing, to control the flow of the cold dry nitrogen gas from said source of only cold dry nitrogen gas to said housing. v