US 2544183 A
Description (OCR text may contain errors)
March 6, 1951 P. s. ROGERS ET AL l 2,544,183
AIRCRAFT RADIO COOLING Filed Aug. 7, 1948 Patented Mar. 6, 1951 AIRCRAFT- RADIO COOLING Philip S'." Rogers, Willard O. Emmons, John W. Godfrey, and James Milton Kelso, Lockport, N. Y., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 7, 194.8, Serial No. 43,054
For' aircraft installation of radio, radar and other electronicY tube equipment it becomes important to use airtight enclosures to seal against moisture and change of barometricl pressure.
`This introduces the problem of dissipating heat produced upon operation of the equipment in Vbox may be caused to circulate over the tube equipment and through a cooler for transferring neat from the interior of the sealed enclosure to outside atmosphere. Suitable motor driven fans blow both inside'and outside air through the cooler and may be controlled either manually or by a thermostatic switch in response automatically to temperature requirements.
A convenient, simple and inexpensive cooler arrangement can be built into and constitute a part of the sealed enclosure and according to a preferred embodiment of the present invention the cooler will involve passages for air circulation with a multitude of ne gauge wires or pins bridging the passage space. The pins assist in increasing the rate of heat transfer through the passage wall between the hot and cold fluids and the smaller the bulk or diameter of individual pins in relation to the exposed surface area the more ellective will be the working of the pin material and the greater the number of wire pins within the limit of permissible fluid ow resistance the greater will be the rate of transfer.
To eliminate difliculties of fitting individually formed pins Within the flowipassages it is here proposed greatly to simplify the manufacture of a pin type heat exchanger by the preformation from a single piece of wire of a group of joined together pins arranged so that the connecting portions between the successive pins also provide` seating abutments and joining parts with the passage walls. To that end a small diameter Wire is helically wound about a mandrel or otherwise formed into a continuous succession of narrow elongated or flattened coils in which the pins are aorded by the straight wire lengths between return bends or end loops and a series of the pins and a number of rows of coiled pins may be handled as a unit and in the assembling operation they are placed between adjacent wall surfaces of a stack of fiat plates with the spaced apart wall surfaces of each passage abutting opposite end loops of the wire coil and with the wire lengths between the end loops extending straight across the passage space. The parts 4 Claims. (Cl. 257-244) while so located temporarily in a holding fixture may be brazed or otherwise secured together at the several abutment points and the result is a rugged cooler assembly with the pins tying together and spacing apart the flat wall plat/es.
To suit installation requirements a number of plates and the grouping and character of the pins may be embodied in various arrangements within the scope of this invention to be further described in connection with the accompanying drawing wherein Figure l is a side elevation of a heat exchanger in operative relation with electronic tube equipment; Figure 2 is a section taken on line 2-2 of Figure 1; Figure 3 is a fragmentary elevation as viewed on line 3 3 of Figure 2 and Figure 4 is a detail perspective View of the coil wire pin detail. v
Referring to the drawing the electronictube equipment is illustrated generally at 5 within a sealed contained 6 having a wall carried cooler Aunit to which heat transfer uids are delivered by suitable motor driven fan devices 'I and 8. While air will be a convenient medium for absorbing and conveying heat from the tube to the outside it will be understood that other fluids may be used and thus the sealed interior of the container may be considered as being lled with a moisture free nonoxidizing gas.
The cooler unit shown includes three spaced apart and parallel flat plates or walls 9, l0 and II with wire pins in annular array extending across the space between and joining the two end walls 9 and I I with the central division Wall I0. It is of a circular type in that incoming air enters at the centerandflows radially outwardly over and around the annular bank ofspaced pins within the wall passages and discharges at the circumference or periphery of the end walls 9 and Ii. The intermediate division wall Ell is imperforate and forms a part of the sealed compartment vvall. Conveniently it fits over and closes an opening in one of the compartment walls and its marginal edge extends beyond the opening to provide a mounting flange secured by clamp bolts I2 and sealed by a gasket I3. Additional spaced walls arranged side by side may be used to provide more passages if a relatively heavy heat load needs attention, but in the present embodiment the end walls 9V and Il are in the nature of annular rings or flanges on the adjacent ends of a pair of tubular conduits I4 and I5 which project in opposite directions away from the central division wall Ill and are coupled respectively with the delivery outlets of the blowers l and 8.
The wire pins referred to are the straight portions extending between the end loops of a flat coil I6 of helically wound wire. In each air space several rows of pins vmay be all o one continuous piece of wire, which after being wound into narrow elongated coil form, as seen in Figure 4, may fbe placed upon a spindle whose ldiameter substantially corresponds to the tubular members I4 and l5 and wrapped around the spindle and upon itself several times to build up the desired number of substantially concentric rings or convolutions. `Seven of such convolutions are shown in Figure 2 with the end loops between succeeding pins abutting the passage walls. Optionally eachri'ng or convolution of the coil wire may be separate from the others, in which case each ring would be a length of wire coil joined end to end in annular form to be nested successively within or upon one another with succeeding rings having progressively more 'coils as the ring diameter increases.
For good heat transfer it is proposed that the wire pins, and at least the imperforate separator wall i0, be formed of aluminum and that the several pieces be preformed and then bought together and held in a xture to be brazed by dipping in a molten salt bath.
There is thus provided in an economical manner a strong structure usable in a small space and employing wire pins having a high ccedicient of heat transfer and which eliminates the fabrication and handling troubles and expense which would be encountered with an assembly of individually placed pins between flat wall surfaces.
1. For the dissipation of heat from electronic equip-ment enclosed within an airtight container for installation on aircraft, a heat exchanger including a central plate 4for closing and sealing attachment over lan opening in the container wall, a pair of end plates on opposite sides of and spaced from the central plate with oppositely projected tubular formations constituting incoming conduits for connection with air blowers placed inside and outside the container vand vfor directing blower air for outward flow through the respective spaces between 'opposite faces of the central plate and said end plates and a succes sion of circular runs of helically coiled Wire within each of said spaces, each run being closely tted to its neighbor run and having narrow elongated coils, whose opposite end loops are fixedly joined to the space defining plates and whose iiat sides extend as nely separated straight pins across the spaces.
2. For use with a sealed container enclosing apparatus which generates heat upon operation, means to transfer such heat to the outside atmosphere including a container wall, sets of wire pins on both faces of said Wall, each set comprising in radial succession a series of circular rows of helically wound wire having flat sides and opposite end loops with the loops at one end xed to said wall, a pair of tubular members on opposite sides of said wall terminating in radial flanges xed yto the other end loops andspaced from the wall to afford therebetween air flow passages bridged by multitudinous pins provided by the flat sides of the helically wound wire, said tubular members constituting conduits for air flow through said means.
'3. In a heat exchanger of the character described, afseparator wall common to two air ow passages on opposite faces thereof, inner and outer ring-like plates on opposite sides of said wall and cooperating therewith to form said air ilow passages, said ring-like plates having tubular projections extending centrally thereof in opposite directions to one another, and a series of space bridging pins in the passages on both sides of said wall, said pins being the straight portions of flat narrow coils o1' helically wound wire, whose end loops are xedly secured to the wall and the plates and which are arranged in circular formation peripherally beyond said tubularproj ections and in radially successive rows.
4. In a heat exchanger of the character described, a pair of tubular conduits arranged substantially end to end and terminated at adjacent ends in radially outward flanges spaced from each other, an imperi'orate wall intermediate and spaced between both flanges, and a series of substantially concentric rings of helical wire coils f spanning each of the spaces between opposite faces `of said wall and said anges, each coil being rlxedly secured to the wall and an adjacent flange.
PHILIP S. ROGERS. WILLARD O. EMMONS. J OHN W. GODF'REY. JAMES MILTON KELSO.
REFERENCES CITED The following references are of record in the file vof this patent:
UNITED STATES PATENTS Number