US3543842A - Device for elastic and heat conducting connection of thermo-couples - Google Patents

Description

United States Patent [72] Inventor Veit Merges 3,127,157 3/1964 Webb 267/1 Munich, Germany 3,129,116 4/1964 Corry 136/204X [21] Appl. No. 673,517 3,129,531 4/1964 Connor 52/167X [22] Filed ct.6, 1967 3,197,343 7/1965 Palmatier.. 136/212 Patented Dec. 1, 1970 3,208,877 9/1965 Merry 136/212X [73] Assignee Bolkow Gesellschaft mit beschrankter 3,234,048 6 Nelson 1 6/23 X Haftung 3,266,944 8/1966 Spira et a1... 136/230X Ottobrunn near Munich, Germany 3,269,875 8/1966 White 136/212 [32] Priority Oct. 13,1966 3,325,312 6/1967 Sonntag,Jr 136/230X [33] Germany 3,326,727 6/1967 Fritts 136/221X [31] B89339 Primary Examiner-Winston A. Douglas Assistant ExaminerA. Bekelman s41 DEVICE FOR ELASTIC AND HEAT CONDUCTING 616w and CONNECTION 0F THERMO-COUPLES 4Cla'mS2Drawmg ABSTRACT: A device for the elastic and heat conducting [52] U.S.C1 165/82, nn c i n of he c ld ends of th rmo uples of a ther- 165/185, 136/205, 267/1, 248/24 mogenerator with a radiator includes a supporting plate facing [51] 1nt.Cl F28f 7/00, the radiator and a pressure plate facing the cold ends of the Hol 1/30 thermocouples. A plurality of flaccid bodies such as loosely Field ofSearch 136/202 supported mul i raid cable sections of twisted silver fila- 204, 205 208-212, 221, 229, 230; 62/3; ments are connected between the pressure plate and the sup- 165/81, 185, 82; 52/573, 167; 267/70, porting plate along with an energy accumulator arranged and 162(1nquired); 188/(1nquired); 248/18, 24 upported so that the supporting plates and the pressure plate are biased away from each other toward Contact with the respective radiator and thermocouple but are movable about [56] References Cited at least two mutually perpendicular axes without disrupting UNITED STATES PATENTS conductive contact. The supporting plate is securely con- 1,633,697 6/1927 Davis et a1. 267/ nected to the radiator and is provided with an opening 1,744,551 l/1930 Karcher..... 267/70 therethrough for receiving an adjustable bearing body which 1,834,001 12/1931 Modine 165/82 encompasses the energy accumulator which comprises a plu- 2,859,948 11/1958 Callard 165/82 rality of plate springs. The plate springs are disposed around 3,082,276 3/1963 Corry et a1 136/205 a centrally arranged pressure body which rests on the pres- 3,110,628 1 H1963 Ramey. rcl 1 /2 sure plate facing the cold side ofthe thermocouple.

I f 15 ll 23 12 e 8 7 p '1 1. oy i a f x ex V I I V I v V r/ I I I. l pq i: l j; 2 1 i' y X 1 k :v x a S Pitented Dec. 1, 1970 Shut L 0:2-

INVENTOF? Ve it Merges BY M r H ATTORNEYS Paten t ed Dec. 1, M70

Shoat of 2 mvsmoa eit Mergg ATTQRNEY-S DEVICE FOR ELASTIC AND HEAT CONDUCTING CONNECTION F THERMO-COUPLES SUMMARY OF THE INVENTION This invention relates, in general, to thermocouples and heat-conducting connections therefor and, in particular, to a new and useful device for the elastic and heat conduction connection of the cold ends of a thermocouple of a thermogenera-- tor with a radiator.

A thermogenerator of a type, for example, which is heated radioactively, may be arranged against the hot sides of a thermocouple and the opposite or cold side of the thermocouple is adapted to be connected to a radiator. The efficiency of energy conversion in such a thermogenerator depends not only on the efficiency of the individual thermocouple but is also determined substantially by the obtainable temperature difference between the hot and cold sides of the thermocouple. The efficiency of the thermocouple may be increased by the proper selection of suitable semiconductor connections, and the capacity of such thermogenerator can be increased by improving the heat transfer between the heat yielding core and the individual thermocouples and between the thermocouples and the radiator giving off heat to the outside. It is difficult to provide for the proper interconnection of the thermocouple with the heat yielding core and the radiator because of the high temperature gradient between the surface of the core yielding the heat and the radiator connected with the cold end of the thermocouple. This temperature difference produces considerable heat expansion in all of the structural parts which participate in the heat conduction. Because such parts will consist necessarily of different materials, 'there will be different expansions and contractions of each part because of the different coefficients of expansion of the materials employed.

The shaped parts carrying the thermocouples as well as the structural parts associated with the thermocouples must be able to follow the thermal expansions without interference with the heat contact between the parts. The maintenance of good heat contact determines the output of the thermogenerator between the hot side of each thermocouple and the heatyielding core as well as between the cold side of the thermocouple and the radiator. When thermogenerators of this type are used for energy sources for satellites, additional loads occur during orbiting, for example, around the earth, because upon entrance into the earth's shadow, the temperature difference between the hot and cold sides change. When such thermogenerators are used in satellites which are brought into their orbit by. carrier rockets, all the structural parts must be mechanically secured with sufficient firmness so that they can withstand the change of position due to acceleration, vibration, etc. that may occur when a rocket, for example, is set off. In view of the fact that such devices are used for extraterrestial use, an optimum dimensioning of the structural parts is desirable, because any saving in weight of the thermogenerator increases the proportional payload.

Prior to the present invention, devices have been known for biasing the thermocouple hot side against the heat yielding core. The known arrangements, however, provide for only poor heat conduction and they do not permit the pressing of the thermocouples onto the heat yielding core in a satisfactory manner. With the known arrangement, the large area contact necessary for satisfactory heat contact between the individual structural elements cannot be obtained because of the different thermal expansion of the materials with which the structural elements are made. To avoid jamming between the pressure bodies and the bearing bodies of such devices, either sufficiently great bearing clearances are required for the maintenance of very special production tolerances are necessary. At great bearing clearances, the desired heat transfer between the bearing body and the pressure body is doubtful.

It has been found further that the use of biasing devices such as helical springs are not suitable as mechanical pressure accumulators for furnishing uniform contact pressures over the occurring temperature ranges. in addition, the shaped parts carrying the thermocouples are usually welded to the radiators so that the relatively great form variations due to thermal expansions are inevitable and this again causes an efficiency reduction on the overall operational characteristics of the thermogenerator.

In accordance with the invention, there is provided a simple and reliable means for effecting the elastic and heat-conducting connection of the cold ends of thermocouples of a thermogenerator with the radiator. The arrangement comprises the use of flaccid bodies, for example, twisted silver filaments loosely arranged between a supporting plate adapted to be connected to the radiator and a pressure plate adapted to overlie the coldend of the thermocouple. in addition, an accumulator is disposed between these two parts to provide for a uniform pressure under all operating conditions without hindering the structure holding the thermocouple from changing position as a result of any temperature fluctuations. The arrangement also permits the transmission of the heat under all operating conditions through the thermocouple from the cold side as completely as possibleto a heat radiating surface or to a heat exchanger such as a radiator. The individual thermocouple is always held in optimum heat contact with the heat yielding core, and the individual heat flow from the cold side of each thermocouple to the radiator is insured. The flaccid bodies are arranged so that the supporting and pressure plates are movably mounted for movement along at least two mutually perpendicular axes. These flaccid bodies comprise several multibraided cable sections of twisted silver filaments. Such cables are known in connection with thermogenerators, but they have only been used for current conduction. The inventive construction is such that the supporting plates supply full face against the thermocouple as well as against the radiator in all operative states of the thermogenerator because the bodies connecting them can adapt themselves to movements in all degrees of freedom without unduly stressing the structural elements associated therewith because of the use of the inherently elastic flaccid constitution.

A device of the invention is extremely easy to produce, particularly because no fitting pieces with mutually sliding surfaces need be provided. The supporting plate is preferably rigidly connected with the radiator and receives an adjustable ring body providing a guide for an energy accumulator which is retained therein. The energy accumulator concentrically encloses a cylindrical pressure body which rests on the pressure plate facing the cold side of the thermocouple and which is freely movable over the surface thereof. In such a construction, the mechanical energy accumulator naturally participates'in the heat production between the thermocouple and the radiator, but the heat finds its way mainly through the flaccid body cable connections. The pressure plate rests against the cold terminal of the thermocouple under the holding force of theenergy accumulator and through the flaccid body conductors. Therefore, all of the parts will be maintained in contact pressure, even though they must follow changes in the condition of structural elements clue to heat changes. The arrangement is such that the full face application of the pressure plate on the cold side of the thermocouple is always maintained.

In one embodiment of the invention, the mechanical accumulator comprises stacked plate springs. in another embodiment, the mechanical accumulator comprises a bellows which is filled with a gas such as a rare gas.

Accordingly, it is an object of the invention to provide an improved connection between the radiator for the cold side of a thermocouple and the heat yielding core wherein the parts are held in good thermocontact relationship despite changes of position of the parts due to temperature changes.

A further object of the invention is to provide a device for the elastic and heat conducting connection of the cold end of a thermocouple of a thermogenerator with a radiator using a supporting plate which is disposed in secure contacting en gagement with the radiator and a pressure plate in close proximity to the cold side of the thermocouple and using a plurality of flaccid conductor bodies connected between the supporting plate and the pressure plate in a manner permitting relative movement of these plates in two perpendicular planes and also including a mechanical accumulator disposed between the plates to provide a resilient holding force. 7

' A further object of the invention is to provide a device for connecting cold ends of a thermocouple of thermogenerators with a radiator which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a partial transverse sectional view of a thermogenerator constructed in accordance with the invention; and

FIG. 2 is a view similar to FIG. 1 of another embodiment of the invention. 12

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS outwardly from the insulating layer 6 and carries electricaljunctions or terminals 8. A pressure plate is disposed adjacent the cold side 7 and is insulated electrically therefrom by an electrical insulation layer 9. A radiator 14 is spaced away from the pressure plate 10 and a supporting plate 12 is secured to the radiator in good heat contact therewith.

' In accordance with the invention, a plurality of flaccid conductor bodies 11 are secured at their respective ends to supporting plate 12 and pressure plate 10, respectively. The flaccid bodies 11 are designed as multibraid cable sections of twisted silver filaments andthey are connected to the respective plates 12 and 10 by solder connections 15, 15. The solder connection provides for good heat conduction and permits radiation of the heat given off by the thermocouples through the flaccid bodies and to the radiator where it is radiated to the outside.

In accordance with a further feature of the invention, the supporting plate 12 is provided with a threaded bore 16 into which is threaded a bearing body 17. The bearing body 17 in.- cludes a large diameter bore or cutout portion 18 and a smaller diameter portion 19 defining a ledge or end face 24 therebetween. The bearing body 17 is long enough so that it extends into a recess or slot 20 defined in the radiator 14. A cylindrical pressure body 21 having a widened external flange or collar portion 22 is positioned over the pressure plate 10 with its collar portion 22 in tight engagement therewith. Plate springs 23 are stacked around the pressure body 21 and located within the cutout 18 in a manner such that one end bears against the end face 24 and the other end bears against the flange or collar 22. The plate springs 23 areclamped between the bearing body 17 carried by the supporting plate which bears against the radiator and the pressure body 21 which bears against the pressure plate 10 which is arranged adjacent the cold side 7 of the thermocouple 3. The plate springs 23 insure a continuous and uniform contact pressure on the pressure plate 10 in accordance with the initial setting of the stresses of these springs. Due to this arrangement, the pressure plate 10 is freely movable within certain limits relative to the supporting plate 12 in an axial, radial and in-plane parallel direction so that regardless'of changes of position between the core 5 and the radiator 14 caused by thermal expansions there will still be a reliable full-face and hence good heat-conducting connection between the heat yielding core 5 and the hot side 4 of the thermocouple 3, the cold side 7 of the thermocouple, and the pressure and supporting plates 10 and 12 and the radiator 14.

The middle flaccid bodies 11 provide for heat conduction and they are such that they can follow any change in position between pressure plate 10 and supporting plate 12 and permit the expansion and contraction or even movement of the springs 23. Even a sliding movement between the pressure plate 10 and the pressure body 21 in a radial direction is possible without producing any effect on the contact between the core, the thermocouple and the radiator.

In the embodiment indicated in FIG. 2, the radiator 14' includes a relatively small diameter bore 20' which receives a pin projection 27 of a cover member or supporting plate 26. The thermocouple 3' is' connected with the radiator 14' through an elastic housing 25 which includes the supporting plate 26. In addition, there are provided bellows 29 and a central bottom 28 which bears against the cold side 7' over an electrical insulating sheet 9'. The bottom 28, together with the part 15, define a supporting plate similar to the other embodiment. The housing of the bellows 29 is advantageously made of a special steel, and to obtain a desired good heat conductivity, the housing is traversed between the cover 26 and the bottom 28 by a plurality of circularly arranged flaccid body conductors 11. In the same manner as in the embodiment of FIG. 1, the flaccid bodies 11' are connected at their respective ends with the cover 26 and the bottom 28, respectively, such as by welding to provide for good heat conduction. The energy accumulator comprises a rare gas which is contained in the housing 25. For example, a rare gas such as helium whose pressure rises in accordance with the temperature rise of the gas in operation is employed. This permits the extraterrestial of the device where the atmospheric pressure will disappear.

In each of the embodiments, the supporting plate and the pressure plate and their connections therebetween permit good thermal conduction regardless of the expansions or contractions of the various parts. In the embodiment of FIG. 2, the container 25 is advantageously made pressure proof along with the solder connection for the flaccid bodies 11' and the cover 26 and the bottom 28.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

I claim:

1. A device for the elastic and heat conducting connection of the cold'ends of thermocouples of thermogenerators with a radiator, comprising a supporting plate adapted to face against said radiator, a pressure plate adapted to face against the cold end of the thermocouple, a plurality of substantially circularly arranged flaccid body conductor elements connected between said pressure plate and said supporting plate, said supporting plate being adapted to be securely connected to the radiator and havingan opening therethrough, a bearing body secured in the opening ofsaid supporting plate and defining an internal ledge with a bore opening to an end adjacent said pressure plate, a cylindrical pressure body arranged within the bore of said bearing body, said cylindrical pressure body having an external flange disposed in contact with said pressure plate and spring means disposed around said cylindrical pressure body and tensioned between said bearing body'internal ledge and said cylindrical pressure body external flange.

2. A device, according to claim 1, wherein said flaccid body I r is multibraided cable sections of twisted silver filaments.

3. A device, according to claim 1, wherein said spring means comprises a plurality of stacked plate springs.

4. A device, according to claim 1, wherein said flaccid body comprises a plurality of twisted cable sections limseh splfail) wound and widened between said supporting plate and \llld pressure plate.

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