Vacuum tube shield and heat radiator

May 15, 1956

E. J. L1DEEN 2,745,895

VACUUM TUBE SHIELD AND HEAT RADIATOR

Filed June 9, 1951

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United States Patent Office 2,745395

-____________ _________________ Patented May 15, 1956

Fig. 4 is a view similar to Fig. 2, showing shield of this invention installed on a “peanut tube ” form’o? Σ' V^^{iIar t0 Fig}· ⁴’ ^{showing a} modified ^h‘^v,ns * ““ “oFig. 6 is a plan view of a portion of a strip of metal which has been severed longitudinally prior to corrugaof F^' ^{&amp; Plan Vi}®^W °^{f a poriion of haIf} ώε strip or rig. 6 after corrugation, and * '^{S a} Perspective view showing a corrugated ’ ^c*^a“^{al !h}·”·-«·“ ^{COnCept Of the Vacuum} tube cooler and roeated^fnw ^ln_f^{Veatl0n ls to} P^rovide a longitudinally cor™^gat5^{d piec}® ^{of she}et metal, which is bent to a cylindrical shape about a longitudinal axis and slipped over a vacuum tube. The bottom edge of the corrugated cylinaffiuralffAif “ ^{irregular contol,r} so to to provide Lt enni^{y P}°^{rtS at the bot£om of} ‘he shield so that cool air may enter near the base of the tube and Sow upwardly through the space defined by the :/-.:XiTsLS -= ·« “» «X cal corrugated strip, regardless of whether its primary purpose is to prevent electrical interference or simpJ m 30 ^fa“^lltat.® the transfer of the dissipation of heat.

the shSld tn°^f ‘A ^drawin“ ^a Preferred embodiment of mbe ii Th _t^sh°^wa “Stalled on a glass-walled vacuum gm, r^{h l}-^{Ube 11 1S of the ty}P^e having generally upwardly diverging side walls, and the upner portion of ^{35 Ub}%^1S ϊΐ^{δβΓ ftan the base}· Accordingly the shield ,θ I ^pre.^ferably supported on a grounding ring (shown in broken lines) which is fixed to the metal chassis 13.

, he shield 10 is formed of a substantially rectangular piece of sheet metal, preferably thin aluminum, which 40 ¹⁸ corrugated and bent to a cylindrical shape. The ends of the sheet indicated at 14 and 15 are slipped over one another so that the corrugations interlock as shown Jf toTtSr bnAh^{S be riVet6d} °^{r otherwise} fastened cSes* The hA^{1S 1S π}°^{£ nec}®ssary or desirable in most 45 “ses. ^The bottom of the sheet which forms the shield 10, is cut to have a scalloped edge in order to provide a plurality of air inlet openings 15, thus each of the flutes onenTtt T A® ^{10 by the c}&lt;“rugations is open to the atmosphere outside of the grounding ring 12 ⁵⁰ λΑκ^Αια® °^f ΐ® ^tUbe‘ ^{This allows air i0 flow} into the shield 10, up the flutes 17, over the tube 11 and out of the top end of the shield as indicated by the arrows and both the tube and the shield are continually cooled by a rising column of air.

⁵⁵ λ ^Tbc, ^ms!^{de of th}e shield 10 contacts the glass wall of the tube 11 near the top of the tube and, accordingly ^h®.^at. ,^ls frensferred by conduction from the tube to the shield. Similarly heat is transferred directly by radia“°ⁿ ίθ?, ΐη ^various P^arts of the tube to the shield.

₆₀ The shield 10, of course, is also cooled on the outside by convection and radiation in addition to the coolin'· effect to tne air flowing upwardly through the flutes 17° In some cases it has proved desirable to employ a cylin_. . . “ , . drical sleeve around the outer surface of the shield 10 in rig. 1 is a perspective view of a glass walled vacuum 65 ^{order t0} provide exterior ducts to promote air circulation -...- --------- -..... over the outside of the shield 10. In most instances however, the construction shown is adequate.

The natural resiliency of the corrugated shield 10 causes it to engage the sidewall of the tube 11 and the &gt; locking ring securely and also makes some variation in size possible, since the shield may be stretched to slin over tubes or rings which are somewhat larger than the normal diameter of the shield. Similarly the engaging

2,745,895

VACUUM TUBE SHIELD AND HEAT RADIATOR Ernest J. Lideen, Cicero, III.

Application June 9, 1951, Serial No. 230,770 7 Claims. (Cl. 174—35)

This invention relates generally to vacuum tubes and more particularly to a combination radiation shield and heat radiator for use with such tubes.

In radio and television receivers and transmitters it is frequently advantageous to provide grounded shields to prevent interference between certain vacuum tubes and other components of the circuits. This is particularly true when glass walled tubes are employed in the radio frequency portions of the circuits.

Most vacuum tubes will operate more efficiently over long periods of time if they are cooled so that they cannot become overheated, as is likely to occur when the heat developed by the tube filaments is not dissipated to the atmosphere at a high enough rate.

When conventional tube shields are employed to protect against radiation and stray fields the shields tend to decrease the rate of heat transfer from the tube to the atmosphere, with a result that the tubes are even more likely to become overheated so that their effective life is shortened.

Accordingly, one important object of this invention is to provide a tube shield which increases rather than decreases in the rate at which heat transferred from the tube yet which completely encloses the tube to prevent electrical interference.

Another object is to provide a cylindrical element which may be slipped over a metal walled vacuum tube, where shielding is of little importance, and which will increase the rate of heat transfer from the tube so that the tube will operate at a lower temperature.

A further object is to provide the tube shield which forms a finned radiator around the tube, having vertically disposed air ducts along the sides of the tube so that the tube may be cooled by conduction, radiation and convection.

A further ooject is a tube shield which also may be used as a shielding element or heat radiator or both for condensers, whether dry or electrolytic, and other circuit elements, the shield also being adapted to enclose either circular or non-circular elements.

Another object is to provide a cylindrical shield which may be easily fabricated from sheet material and whose diameter may be adjusted to suit various sized tubes.

Other objects and advantages of the combination tube shield and radiator of this invention will present themselves to those familiar with the art on reading the following specification in conjunction with the drawings and appended claims.

In the drawing:

^^e. tube is larger than the base.

tube provided with the shield of this invention.

Fig. 2 is an elevation showing the manner in which the shield of this invention is used with a glass walled tube having straight sides, the shield being shown in section.

Fig. 3 is a view similar to Fig. 2, showing another ⁷θ form of the shield installed on metal tube as a heat radiator.

Λ edges 14 and 15 may be disengaged and made to overlap one or more additional corrugations to increase, or decrease diameter of the shield 10, thus a given shield may be used with tubes of many different sizes, making it unnecessary to· manufacture and stock large numbers of shields. The resiliency of the sidewall also makes it possible to use the, shield. 10 on non-circular cylindrical or prismatic objects since the shield tends to. follow the. shortest periphery when stretched over an object. This makes it possible to use the shield .IQ. on most types of circuit components including condensers.

In Fig. 2, a shield 10 is shown installed, on a. tube Ha having cylindrical sidewalls. In this, installation, no grounding ring is used, the, fluted, ends of the shield merely resting on. the chassis 13. to ground the shield. In this installation the fluted sides of the shield 10 engage substantial portions of the tube wall to effect heat transfer by conduction from the tube to the shield. The lower end of the shield 1© is scalloped to provide air inlet ports 18 and engages the tube socket 20.

The manner in which the shield of this invention, may be used as a cooler for a metal tube 116 is shown in Fig. 3. In this case the function of the shield 10 is primarily to cool the tube lib, and, accordingly, the shield is slipped directly over the metal shell of. the tube and. is not separately grounded. The shield 1.06 contacts the walls of the tube lib along its entire length to effect, very good conductive heat transfer from the metal of the tube to the shield. The internal flutes 176 form a plurality of chimneys or ducts about the side of the. tube through which cool air flows by convection,, the chimney effect substantially increasing the rate of heat transfer, over that which would occur if the tube were merely exposed to static air. The shield 106 differs from the preferred embodiment in that both its upper and lower ends are scalloped. Otherwise it is identical, the scalloping of the upper end serving no function when the top of the tube is not covered. The scalloped upper end results when a number of narrow strips are.cut from, a wide

This will be clarified in the description of Figs. 6-8 which follows: .,

In Fig. 4 a smaller sized shield 10c is shown installed on “peanut” or baseless type tube lie. This embodi10 strin to form the blanks from which the shields are formed. 40 selves to those familiar to the art may be made without ^H ____ . . . , T?:— c. q j____tXX invAitfinn +hp ςρηηρ. of

2,746,895 modified form of corrugation wherein the wave form is square or rectangular instead of sinusoidal. This produces somewhat better conductive heat transfer because of the larger area of contact. . .

A preferred method of making the corrugated shields of this invention is shown in Fig. 6-8. The first step in this method is to sever an elongated strip of sheet metal into two halves along a sinusoidal line as indicated, at 24. This cut 24 serves to form the scalloped edge which forms the inlet ports 16 after the strips have been corrugated. The next step of the process is to take either half of the. longitudinally severed strip and pass it. through corrugating rolls to give it the shape shown in Fig. 7. It is preferred that the scallops formed by the cut 24.be in register with the corrugations so that when the shield is formed each of the internal flutes 17 is provided with a port 18 at its lower end. However, registration between the scallops and the flutes is not necessary, and, if the period of the sinusoidal variation of the scalloped edge is different from the period of the sinusoidal corrugation, random spacing will result with the further result that the bottoms of the flutes 17 will be sufficiently open to permit free air flow.

In Fig. 8, a corrugated strip is shown after having been 25 cut to length and bent to form a cylinder. The step of cutting the strips to length may be performed, before the corrugation step, if desired, and when this is done the corrugated rollers can be so arranged to bend the strip into a cylinder during corrugation.

From the foregoing, it will be apparent that a superior shield has been provided, which not only encloses the circuit element to be shielded but also promotes the cooling thereof and is useful as a cooling element even when shielding is not required, moreover, the device of this invention is universal in size so as to accommodate tubes or elements of different diameters and shapes and is inexpensively and easily fabricated.

Various other changes or modifications in addition to those set forth herein and such as will present them·' t departing from the spirit of this invention the scope of which is commensurate with the following claims.