US3586100A

US3586100A - Heat dissipating devices for the collectors of electron-beam tube

Info

Publication number: US3586100A
Application number: US809258A
Authority: US
Inventors: Susumu Yasuda; Ryuzo Orui
Original assignee: Nippon Electric Co Ltd
Current assignee: NEC Corp
Priority date: 1968-09-28
Filing date: 1969-03-21
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22

Abstract

A heat-dissipating device for the collectors of electron-beam tubes such as a traveling wave tube. The collector slides loosely into a bore within a cylindrical heat-absorbing and conducting member. The heat-absorbing member is connected to a finned heatradiating structure to which heat is conducted for dissipation. A tight fitting between the collector and the heat-absorbing member is created by the presence of a restraining collar placed around the heat-absorbing member. The collar has a smaller coefficient of expansion than the heat-absorbing member, and the heatabsorbing member has longitudinal slots therein, the net effect of which is to cause the heat-absorbing member to constrict about the collector when the assembly heats to operating temperature.

Description

United States Patent [72] Inventors Summu Yuuda;

Ryuo Orul, both of Tokyo, Japan [21 Appl. No. 809,258 [22] Filed Mar. 21, 1969 [45] Patented June 22, 1971 [73] Assignee Nippon Electric Company, Limited Tokyo, Japan [32] Priority Sept. 28, 1968 [33] Japan 1 3/ 158 [54] HEAT DISSIPATING DEVICES FOR THE COLLECTORS 0F ELECTRON-BEAM TUBE 7 Claims, 6 Drawing Figs.

[52] US. CL 165/80, 165/81, 165/185,174/16, 313/40, 313/45, 3171234 A [51] Int. CL H0lj 7/24 [50] Field of Search 317/234 A; 174/16; 313/45,40; 165/80, 185, 81

[56] References Cited UNITED STATES PATENTS 1,715,824 6/1929 Duersten 17 4/15 X Primary Examiner-Albert W. Davis, Jr. Attorney-Sandoe, Hopgood and Calimafde ABSTRACT: A heat-dissipating device for the collectors of electron-beam tubes such as a traveling wave tube. The collector slides loosely into a bore within a cylindrical heat-absorbing and conducting member. The heat-absorbing member is connected to a finned heat-radiating structure to which heat is conducted for dissipation. A tight fitting between the collector and the heat-absorbing member is created by the presence of a restraining collar placed around the heat-absorbing member. The collar has a smaller coefficient of expansion than the heat-absorbing member, and the heat-absorbing member has longitudinal slots therein, the net eflect of which is to cause the heat-absorbing member to constrict about the collector when the assembly heats to operating temperature.

PATENTEDJUNZZIBH 3586,100

INVENT R5 SUML/ 451/04 A ORNEZ IIEAT DISSIPATING DEVICES FOR THE COLLECTORS OF ELECTRON-BEAM TUBE BACKGROUND OF THE INVENTION This invention relates to heat-dissipating devices for heat producing electronic elements and particularly for the collectors of electron-beam tubes such as the traveling-wave tube, backward-wave tube, and the like.

A heat-dissipating system for a traveling-wave tube has been widely used. According to this system, a tapered section of the collector fits into a conical bore of a heat-radiating member and the desired fit between the two concentric conical contacting surfaces is maintained by adjusting a clamping nut fitted on a threaded boltlike projection at the end of the collector.

The cooling efficiency of such a device for the collector has been found to be considerably higher when the two conical contacting surfaces of the collector and the heat radiating member are fitted tightly together. The need for manual control of the clamping nut, however, is inconvenient, in that it restricts the mounting position of thetraveling-wave tube in the microwave communication equipment to positions where the clamping nut is accessible.

The ever-increasing demand for greater miniaturization of present-day electronic equipment has necessitated the efficient utilization of available space and a higher concentration per unit volume of component parts, including traveling-wave tubes in microwave communication equipment. In extreme cases, the heat-radiating member of a traveling-wave tube must be positioned in a remote location in the equipment in order to provide ease of tube replacement from the opposite side, which positioning prohibits manual adjustments of the aforementioned variety.

Therefore, there has been an increasing demand among equipment designers and users for the advent of a new heatdissipating system for the collectors of electron-beam tubes which dispenses with the need for such clamping nut adjustment in tube insertion or removal.

It is consequently a general object of this invention to provide a new and improved heat-dissipating system for the collectors of electron-beam tubes which overcomes the aforementioned difiiculties of the prior art. Stated more particularly, it is an object of this invention to provide a new and improved heat-dissipating device for the collectors of electronbeam tubes which dispenses with manual control of the clamping nut as in the prior art, automatically provides a tight fit between the contacting surfaces of the collector and the heatconducting element after the tube has been operated for a predetermined time interval, and which further enables tube removal after the tube operation has been suspended for a predetermined time interval.

SUMMARY A heat-dissipating device according to this invention comprises a heat transfer or conducting member, generally but not exclusively, of cylindrical or tapered cylindrical form provided with a cylindrical or conical axial bore for insertion of the collector of an electron-beam tube, one or more slots in the sides of the heat transfer member extend generally from one end inwardly in the axial direction thereof for a distance corresponding at least to a fraction of the overall length thereof, and. in the transverse direction thereof by a width corresponding to the full wall thickness of the heat transfer member from the bore wall surface to the peripheral wall surface. A neck near the inner end of the heat transfer member generally facilitates the contraction of the slotted side's thereof about the collector. At least one annular retainer means made of a material having a smaller thermal expansion coefiicient than the material of the heat-conducting element fitted around the peripheral surface of the heat transfer member so as to surround at least a fraction of the length of the slotted sides thereof. A heat radiating member of any suitable geometrical shape adapted for heat dissipation is disposed adjacent the heat conducting axial length of the heat-conducting member, or a plurality of slots the opposite ends of each terminate inside of the heatconducting member are suitable alternatives to the abovedescribed slots. An outstanding advantage of this assembly is that a tight fit between the tube collector and the heat transfer element is automatically obtained soon after the tube is put into operation.

The principles of this invention may best be understood by reference to the following description of two preferred embodiments of this invention illustrated in the accompanying drawings. Throughout the specification and drawings, all like parts or members are given like designation numbers to facilitate a better understanding of the invention.

FIG. 1 is a longitudinal cross-sectional view of a heat-dissipating device according to a first preferred embodiment of this invention;

FIG. 2 is an end view of the device shown in FIG. 1;

FIG. 3 is a side viewof a heat-conducting member used in the first embodiment of this in invention shown in FIG. 1;

FIG. 4 is an end view of the heat-conducting element shown in FIG. 3;

FIG. 5 is a longitudinal cross-sectional view of a heat-dissipating device according to a second preferred embodiment of this invention;

FIG. 6 is an end view of the device shown in FIG. 5.

Now referring in more detail to FIGS. 1 and 2, there is shown a heat-dissipating device 1 for dissipating heat produced by the collector 4 of a traveling-wave tube 3 (only the collector and its vicinity thereof are illustrated). The device is composed of .a cylindricaL heat-radiating radiating member 9 provided with an axial bore 9a, and an axial counterbore 9b, and having a plurality of fins 8. A heat-conducting member 7 provided with a flangelike 7a at the inner end for maintaining a low-resistance thermal contact with the internal sidewall surface 10 of the heat-radiating member is attached to surface 10 by member 9 by means of solder or screws. Conducting member 7 has an axial bore 5 therethrough for the insertion of the collector 4, and a pair of symmetrical slots 6 extending inwardly from the outer end of conducting member 7 and disposed in a plane containing the axis of bore 5. An annular member 12 is fitted securely on the peripheral surface 7b of conducting member 7 to impose a restraint on the thermal expansion in the radial direction of the heat-conducting member 7 when the latter is heated.

The heat-conducting element 7 is made of a material possessing a high thermal conductivity and a high thermal expansion coefficient such as aluminum (thermal expansion coefficient is approximately 235x10 whereas the annular member 12 is made of a material possessing a low thermal expansion coefficient such as a nickel-iron alloy containing 36 percent nickel (thermal expansion coefficient is approximately 15x10").

The figures illustrate the structure of the device 1 before being heated to operating temperature.

The diameter of the bore 5 is designed to be larger than the diameter of the collector 4 by tens of microns under this condition. When the tube 3 is placed in operation, a power loss of the collector 4 causes its temperature to rise. Since the collector 4 and the heat-conducting member 7 are initially in partial contact with each other in spite of the presence of a clearance therebetween, the temperatures of

members

7 and 12 begin to rise gradually and simultaneously, and the heat-conducting member 7 beginsto thermally expand.

Since the annular member 12 is made of a material possessing the smaller thermal expansion coelficient of the two, and is initially tightly fitted on the external peripheral surface 7b of the element 7, the outward radial thermal expansion of conducting member 7 is restrained, resulting in the inward expansion of the outer end of the element 7 as indicated by the arrows l6 and I7 (FIG. 2), which inward expansion is substantially perpendicular to the plane containing the slots. Therefore this portion of conducting member 7 is compressed firmly dition of the traveling-wave tube against the collector 4. The constricted neck portion 18 in T,=temperature of heat-conducting member 7 and annular conducting member 7 some distance removed from the edge member 12 fitted thereon under steady operating condiof the annular member 12 to facilitates the inward expansion tions of the traveling-wave tube of the right-hand side of conducting member 7. 5 a, thermal expansion coefficient of the collector 4 The compressive force of conducting member 7 against the a, thermal expansion coefiicient of the heat-conducting collector 4 thus created is extremely large, resulting in a member 7 decrease in thermal resistance between the contacting a, thermal expansion coefficient of the annular member peripheral surface 42 of the collector 4 and surface of bore 5 l 12 in the heat-conducting conducting member 7; and promotes d, diameter of collector 4 under steady state operating efficient conduction of the heat generated by the collector 4 conditions of the traveling-wave tube to the heat-radiating member 9 for subsequent dissipation into 2' diameter of bore at that P of collector which is the air. compressed by

members

7 and 9 in a direction perpen- The region of the collector 4 compressed by the heat-condicular to the plane containing two slots 6 under steady d i member 7 i restricted to that portion which is sup state operating condition of the traveling-wave tube. rounded by the annular member 12. According to our experih and can be expressed as meat, however, excessive local temperature rises at that pordhdll l+a1(T1"T)] (1) tion of the collector 4 not directly compressed are avoided (2) and the temperature I -bution along the axial length of the ln order fobre co7llecltlo;e 4 to be compressed by the heat-concollector 4 made approximately uniform by selecting a collecs fsz tor made of material possessing a high thermal conductivity (such as pp and having a wall sufficiemly thick to m Numerical data for an experimental model which was heat to the region of contact between collector 4 and conductdeslgned and fabricated according to the Second embodlmem g element 7 on the basis of the foregoing equations is as follows:

A second embodiment of this invention is illustrated in Diameter 11 of collector of 3 FIGS. 5 and 6. This embodiment differs from the first in the traveling-wave tube 8.96 mm.

following respects: (a) element 7 is tapered toward the outer Matmal ofthe Copper} Heat dissipation at the collector. 90 watts. end, and annular member l21scorrespondrngly shaped so that Thermal rgsis ance of heat radiatt 1 0 6 0 ct together they form two concentric conical surfaces 13 that fl ff iifj -g "1"": e y can fit together; (b) the end outer portion of element 7 is Tfl-To Material of heat conductin member threaded as shown at 14 and annular member 12 rs mtemally g Aluminum.

threaded to thread thereon. The clearance between the collec- Annula memb 12 a g flfi contaimng tor 4 and the heat-conducting member 7 is initially set by 3 I T1 1 m t 16 4X10 a terrna GXDD-l'lSlOl'l C06 C1611 tlghtenmg annular member 12 on element and no further Estimated temperature difierence between 9 and 7 is approx. 15 C. ad ustment is needed. This adjustment is accomplished before installation of the device in communication equipment. Diameters at various parts of the heat-conducting member 7 The second embodiment functions upon the same principles and the annular member 12 are as indicated in Table 1.

TABLE 1 Thermal expansion Component Material eoefficient Dimensions When traveling-wave tube is left unoperated gore diamezsefi' d t=9.0(11mn. th (1 1 iameter 0 ea con uc ing member at e e go of annu ar Heat conducting member 7. Aluminum 23, 5X10- member=44 Diameter of constricted neck portion 18=26 mm. Annular member 12 N lckel-rron alloy contammg36% mcke1 1. 5X10- Maximum diameter of tapered section d =44 mm.

llginignsional range of the bore diameter in machining was designed 9.05-9.03 mm. and d =9.01 mm. was obtained by suitably turning annular mem er and in substantially the same manner a the embodi f Using the numerical data indicated in Table 1 and the tem- FlG. 1; therefore a detailed description is omitt d, A d. perature rises assumed above,the diameter d of the collector vantage of the second embodiment over the first is that dimen- 4 and the diameter z at the compressing P of the heat-cohi na] tolerances f th mating surfaces

f members

7 and 12 ducting member 7 under operating condition of the tube were l rigorous and machining becomes easier, because the derived by computation as 8.972 mm. and 8.957 mm., respeci hm f fit between

elements

7 and 12 and the clearance tively. Therefore the condition for compression (3) is well between element 7 and collector 4 can be suitably controlled estabhshed' by tightening threaded member 11 In the above experiment, the clearance between the collec- The relationship between the dimensions of various tor 4 and the heat-conducting member 7 was made to be 0.05 ponents and materials to be used therefor which have been f the assembly at so that the tube could easlly be taken into consideration in designing the heapdissipating inserted into and withdrawn from the bore therefrom. it was devices above described are asfoows observed that the compression occurred in about 7 minutes after the tube was put into operation. It was further confirmed SYMBOL DEFINITIONS that the temperatures of collector 4, heat-conducting member 7, and heat'radiating member 9 under steady state of tube temperature operation were 105 C., 93 C., and 80 C., respectively. In diameter the collector 4 of h'avehhg'wave tube view of the allowable maximum temperature of 180 C. for the when the tube is at mom temperature collector, it was confirmed that cooling of the collector was diameter of bore 5 of heat-conducting member when satisfactory. No excessive temperature rise of the collector 4 member 7 ism room l 7 was detected during the 7minute warrnup interval, and the s inside diameter of annular member 12 (maximum tube could be easily withdrawn after the operation of the tube side diameter of the tapered section in case of the second had been suspended for about 45 seconds. embodiment) when at temperature Among the outstanding merits of this invention as reduced T temperature of collector 4 under steady operating coninto practice will be recapitulated.

No manual control on the collector side of the device such as turning the clamping nut is required in tube replacement; he p emen u l santhas e inser d or r d ro the end opposite that of the collector, as the collector slides freely within the heat-dissipating device of the invention. Thus the device may be located at an inaccessible or innermost part in the equipment.

The cooling efiiciency of the devices compares favorably with those of conventional devices for the following. The outward radial thermal expansion of the heat-conducting member is restricted by the provision of at least one annular retaining member possessing a smaller thennal expansion coefficient. This causes inward radial thennal expansion of the heat-conducting member 7, which is further aided by the presence of the slot or slots. As a result, the collector is strongly compressed by the thermally expanded heat-conducting member along at least a fraction of the full length thereof, which reduces the thermal resistance between the contacting surfaces. Even if the temperature rise is not so large, the compression achieved is at least equal to that which could be obtained by tightening the nut according to the conventional design.

Utilization of the invention frees the designer of microwave communication equipment and the like incorporating electron-beam tubes from past restriction arising from the need for access to the heat-dissipating device therefore.

While the principles of the invention have been described in connection with the above specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.

What we claim is:

1. A heat-dissipating device for the collector of an electronbeam tube comprising a heat-radiating member, a heat-conducting member disposed adjacent said heat-radiating member in thermal contact therewith, said heat-conducting member having an axial bore having a normal diameter for relatively loosely receiving therein the collector of an electron-beam tube prior to the operation of the tube, said bore extending from one end of said heat-conducting member inwardly a distance corresponding to at least a fraction of the full length thereof, at least one slot extending in the axial direction of said bore a distance corresponding to at least a fraction of the full length of said heat-conducting member and in the transverse direction thereof the full width of said heatconducting member, and at least one annular member titted on the peripheral surface of said heat-conducting member coaxially therewith and surrounding at least a fraction of the full length thereof containing said at least one slot, said at least one annular member being made of a material possessing a smaller thermal expansion coefficient than that of the material of which said heat-conducting member is made, said annular member defining means when the tube is in operation and thus v heated for acting upon said conducting member to thereby restrain the outward radial expansion of said heat-conducting member. modify the d meter of saidb q. animus: the .91- lector to establish a relatively close fit between the collector and said heat-conducting member.

2. A heat-dissipating device for heat-generating electronic elements or the like comprising: a heat-dissipating structure having a recess therein, heat-conducting means positioned within the recess of and in heat-transferring relationship with said heat-dissipating structure so that heat will flow from said heat-conducting member to said heat-dissipating structure, said heat-conducting means having an aperture therein adapted to slidingly receive a heat-generating element, and at least one substantially longitudinal slot through the body thereof communicating around and against a portion of said heat-conducting means and within a plane substantially normal to the longitudinal axis there to retard outward radial expansion of said heat-conducting means, said band being constructed of a material having a coefficient of expansion substantially smaller than the coefficient of expansion of the material of which said heat-conducting means is constructed, so that when heated by the heat-generating element placed therein, said retaining band means acts on said heat-conducting means to cause the latter to expand radially inwardly and thereby modify the diameter of said aperture to thereby establish a relatively close fit between the heat-generating element and said heat-conducting means.

3. The device of claim 2 wherein said retaining band is disposed around the area of said heat-conducting means containing said slot, and wherein said heat-conducting means has a neck therein, said neck being between the portion of said heat-conducting means having the slot therein and the remainder thereof. 7

4. The device of claim 3 wherein said heat-dissipating structure and said heat-conducting means have a common bore therethrough sized to slidingly receive a collector of an electron-beam tube, and wherein the aperture in said heat-conducting means comprises a portion of the bore.

.5. The device of claim 4 wherein said heat-conductingdevice is substantially cylindrical and has opposing slots therein along a plane containing the longitudinal axis of said heat-conducting device, and extending from the end opposite the neck thereof through said neck.

6. The device of claim 5 wherein said retaining band comprises a ring frictionally fitted around a substantial portion of said cylindrical heat-conducting means containing the opposing slots.

7. The device of claim 6 wherein one end of said heat-conducting means abuts said heat-dissipating structure, and wherein a substantial portion of said heat-conducting means opposite said abutting end tapers outwardly, and wherein said retaining ring tapers correspondingly, and wherein said heatdissipating device is further comprised of means to thread said retaining ring into said heat-conducting means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 ,586 ,100 D t d June 22 1971 lnventor(s) Susumu Yasuda et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 14, after "communicating" insert with the aperture therein, retaining band means disposed Signed and sealed this 2nd day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

1. A heat-dissipating device for the collector of an electronbeam tube comprising a heat-radiating member, a heat-conducting member disposed adjacent said heat-radiating member in thermal contact therewith, said heat-conducting member having an axial bore having a normal diameter for relatively loosely receiving therein the collector of an electron-beam tube prior to the operation of the tube, said bore extending from one end of said heat-conducting member inwardly a distance corresponding to at least a fraction of the full length thereof, at least one slot extending in the axial direction of said bore a distance corresponding to at least a fraction of the full length of said heat-conducting member and in the transverse direction thereof the full width of said heat-conducting member, and at least one annular member fitted on the peripheral surface of said heatconducting member coaxially therewith and surrounding at least a fraction of the full length thereof containing said at least one slot, said at least one annular member being made of a material possessing a smaller thermal expansion coefficient than that of the material of which said heat-conducting member is made, said annular member defining means when the tube is in operation and thus heated for acting upon said conducting member to thereby restrain the outward radial expansion of said heat-conducting member, modify the diameter of said bore, and cause the collector to establish a relatively close fit between the collector and said heat-conducting member.

3. The device of claim 2 wherein said retaining band is disposed around the area of said heat-conducting means containing said slot, and wherein said heat-conducting means has a neck therein, said neck being between the portion of said heat-conducting means having the slot therein and the remainder thereof.

5. The device of claim 4 wherein said heat-conducting device is substantially cylindrical and has opposing slots therein along a plane containing the longitudinal axis of said heat-conducting device, and extending from the end opposite the neck thereof through said neck.

7. The device of claim 6 wherein one end of said heat-conducting means abuts said heat-dissipating structure, and wherein a substantial portion of said heat-conducting means opposite said abutting end tapers outwardly, and wherein said retaining ring tapers correspondingly, and wherein said heat-dissipating device is further comprised of means to thread said retaining ring into said heat-conducting means.