A heat transport system for spacecraft integration

Abstract: An apparatus for transferring heat in a spacecraft comprises a flexible heat pipe (35) having a first section (36), a second section (40), and a flexible section (38). A first member (32) of the spacecraft is coupled to the first section (36) of a the flexible heat pipe (35). A second member (23) of the spacecraft is coupled to the second section (40) of the heat pipe (35). The first member (32) of the spacecraft is in rigidly fixed relationship to the second member (23) of the spacecraft.

Description: BACKGROUND OF THE INVENTION The present invention relates to an apparatus for transferring heat in a spacecraft, comprising a heat pipe (flexible heat pipe) having a first section and a second section, a first member of the spacecraft coupled to the first section of the heat pipe, a second member of the spacecraft coupled to the second section of the heat pipe, wherein the first member of the spacecraft being in a rigidly fixed relationship to the second member of the spacecraft. The present invention also relates to a method of using a flexible heat pipe for transferring heat in a spacecraft and a satellite comprising a radiator, at least one electronic device and an apparatus for transferring heat according to the invention. Such an apparatus is for example known from US 4,880,050. Man has entered a period where spacecraft communication has become an important part of today's society, and there has been a growing demand to increase the capabilities of spacecraft that orbit the earth. As a result, more equipment, such as electronic devices, are carried on-board the spacecraft. Because of the increase in the amount of equipment used in the spacecraft, dissipating the heat generated from the equipment has become an increasing concern. Traditional spacecraft are generally designed with a majority of the equipment mounted directly on the surfaces of the radiator panels that form the side of the outer structure of the spacecraft. This particular arrangement allows the equipment to cool via direct radiation to space. Because the equipment is usually located on the radiator of the spacecraft, signals from the equipment may be reduced or degraded as they travel to other components in other portions of the spacecraft. For example, RF signals that are received by the antenna feeds, located near the center of the satellite, may be reduced when transferred to the communication modules located on the exterior of the radiator panels. Further, the amount of equipment that can be mounted to the radiators is limited by the size and number of radiators. Because the radiators can only be as large as the dimensions of the side of the spacecraft or launcher, the area that is available for mounting the equipment on the radiators usually cannot accommodate the amount of equipment needed for modern spacecraft. US-A-4,880,050 discloses a thermal management system for a spacecraft, which includes a plurality of T-shaped pallets each having a radiator panel and a mounting panel. The mounting panels have electronic equipment mounted thereon. In order to transfer heat from the electronic equipment to the radiator panel, L-shaped external heat pipes contacting both the mounting panel and radiator panel are provided. The heat pipes have flanged portions and are attached to mounting plates by bonding materials or mechanical fasteners. The disadvantage of using a bonding material is that loosening the heat pipes is not easily possible. The problem of using mechanical fasteners is that the alignment of holes provided both in the heat pipe and the radiator panel is difficult and requires high accuracy in fabricating the parts. US-A-5,036,905 discloses a high efficiency deployable heat radiator system for radiating heat generated at a source of heat aboard an orbiting spacecraft or like vehicle. The system comprises radiator panels and a plurality of separate independent heat pipes extending through each panel. Radiator panels comprise separate modular units which may be selectively folded. Each heat pipe therefore has a flexible joint portion to accommodate folding of the radiator panels. The heat pipes are attached to the radiator panels by sandwiching them between upper and lower surfaces of the panels. US-A-4,324,375 discloses a spacecraft modular system with two components of a cooling system. It comprises a loop arrangement through which coolant fluid flows to satellite radiators. The heat pipes are formed by two semi-circular grooves formed in a relatively thin cover plate and base plate. That is, the heat pipes are incorporated into a radiator plate (formed by base plate and cover plate). US-A-5,027,892 discloses an arrangement for mounting a panel on a spacecraft, wherein this panel is pivotably provided to the spacecraft. The radiator panel is provided with heat pipes having flexible sections which permit the panels to pivot for movement between a stowed position and a deployed position. US-A-3,931,532 discloses a thermoelectric power system having a first heat pipe which is employed to couple heat between the hot fluid and hot junction of the thermoelectric element. The surface of the heat pipe serves as a radiator for dissipating heat into space. The radiators are formed from two thin elongated sheets as elongated flexible units adapted to be folded upon launch of the system of a space vehicle and thereafter extended in space to provide a substantial area of radiation of heat to be discharged. Spacecraft have also been developed where the equipment is mounted to shelves within the spacecraft. The heat from the equipment is usually transferred through conventional heat pipes to the radiator for dissipation to space. However, it may be difficult and time consuming to install the heat pipes in the spacecraft. In securing the heat pipes to the radiator and shelves, a fastener is positioned through holes of the heat pipe and into the corresponding holes of the radiator and shelves. Because the holes of the heat pipe have to be properly aligned with the holes of the shelf and radiator, many misalignments may occur during the assembly of the spacecraft. As a result, the holes of the heat pipe may have to be enlarged in order to secure the heat pipe to the shelves and radiator which may compromise its thermal interface and reduce the amount of heat transferred. These problems are magnified when one considers that typical spacecraft have numerous heat pipes. Furthermore, conventional heat pipes that have high tolerance requirements are expensive to manufacture and time consuming to install. There is therefore a need for a heat transport system that allows for easier integration of the heat pipes in spacecraft. The object of the present invention is to provide a device that would simplify manufacturing, reduce labour costs and manufacturing time, facilitate rapid production, minimize the need for custom design, and improve the variability of the thermal joints between the heat pipes. This object is solved by an apparatus which is characterized in that said flexible heat pipe has a flexible section. The present invention achieves the above benefits by providing an improved heat transport system. The present invention allows equipment in a spacecraft to be remotely positioned from the radiator and allows for the transfer of heat from the equipment to the radiator. The present invention also facilitates manufacturing of the spacecraft by alleviating assembly misalignments when securing heat pipes to the shelf and radiator. The present invention preferably reduces design time, decreases production time, and allows for greater use of pre-built production components for spacecraft assembly. According to the invention, the apparatus includes a flexible heat pipe having a first section, a second section, and a flexible section. A first member of a spacecraft is coupled to the first section of the flexible heat pipe, and a second member of a spacecraft is coupled to the second section of the flexible heat pipe. The first member of the spacecraft is in a rigidly fixed relationship to the second member of the spacecraft. According to the invention, a method of using a heat transport system for transferring heat is provided. The method includes the steps of providing a flexible heat pipe having a first section, a second section, and a flexible section, coupling the first section of the flexible heat pipe to a first member of the spacecraft, coupling the second section of the flexible heat pipe to a second member of the spacecraft rigidly fixed with respect to the first member. The invention also relates to a satellite having a radiator, at least one electronic device, and a heat transfer device. The heat transfer device includes a flexible heat pipe having a first section, a second section, and a flexible section. The heat transfer device is coupled to a first member and a second member of the satellite that are rigidly fixed with respect to each other. These and other features and advantages of the invention will become apparent upon a review of the following detailed description of the presently preferred embodiments of the invention, taken in conjunction with the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a module holding compartment, with parts removed for ease of illustration, capable of utilizing the apparatus for transferring heat in a spacecraft of the present invention. FIG. 2 is a perspective view of a preferred embodiment of a flexible heat pipe of the apparatus according to the present invention. FIG. 3 is a perspective view of a preferred embodiment of the first section of the flexible heat pipe of the apparatus according to the present invention. FIG. 4 is a perspective view of a preferred embodiment of the second section of the flexible heat pipe of the apparatus according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, and more particularly to FIG. 1, a preferred embodiment of the invention is illustrated with parts removed. A module holding compartment 10 of a spacecraft is shown. The compartment 10 includes a back wall 16, a base 18, a pair of radiators 20, 22 (shown in phantom), and a plug-in module 32. The radiators 20, 22 are spaced apart and substantially parallel to each other. The back wall 16 of the compartment 10 extends between the radiators 20, 22. The plug-in module 32, such as a shelf, is disposed within the compartment 10. The module 32 preferably has a plurality of electrical devices 34 disposed thereon. Referring to FIG. 2, a preferred embodiment of a flexible heat pipe 35 is shown. The flexible heat pipe 35 is commonly available from many sources such as Swales, Inc. and has a capillary structure (not shown) disposed therein. The flexible heat pipe 35 also contains a heat transfer fluid (not shown), such as ammonia. The flexible heat pipe 35 includes a first section 36, a second section 40, and a flexible section 38. The first section 36 of the flexible heat pipe 35 is mounted to a first member of the spacecraft as shown in FIG. 1. Preferably, the first member is the plug-in module 32. The flexible heat pipe 35 has a plurality of flanges 50 extending from the first section 36. The flanges 50 preferably have a plurality of holes 52. In order to attach the first section 36 to the plug-in module 32, the holes of first section 36 are aligned with corresponding holes in the plug-in module 32. A fastener 54 is disposed through the holes of the plug-in module 32 and the flanges 50 to secure the first section 36 to the plug-in module 32. As those skilled in the art will recognize, the first section 36 of the flexible heat pipe 35 may be embedded into the plug-in module 32 without departing from the spirit and scope of the present invention. The first section 36 of the flexible heat pipe 35 is also in thermal communication with a first component 34, such as an electrical device, heat pipe, or other equipment. A piece of conductive material 56 is preferably disposed between the flanges 50 and the first member 34 to improve the thermal contact between them. (See Fig. 3) Preferably, the material comprises grafoil®. As shown in FIG. 2, the flexible heat pipe 35 has flanges 60 extending from the second section 40. The second section 40 of the flexible heat pipe 35 is mounted to a second member of the spacecraft. Preferably, the second member comprises a heat pipe 23 attached to a radiator 22 as shown in FIGS. 1 and 4. It is contemplated that the second member may comprise a shelf, a radiator, or the like. The second member has a platform 64 attached thereto, and the platform 64 has a plurality of holes 68 therethrough. The flanges 60 of the second section 40 also preferably include a plurality of holes 62 that align with the corresponding holes 68 in the platform 64 in order for the second section 40 to be secured thereto. A fastener 70 is disposed through the holes of the flanges 60 and the platform 64 to secure the second section 40 to the second member. The second section 40 of the heat pipe 35 is also preferably in thermal communication with the platform 64. A piece of material 66 is preferably disposed between the flanges 60 of the second section 40 and the platform 64 to improve thermal contact. Preferably, the material comprises grafoil. As seen in FIG. 2, the flexible section 38 of the flexible heat pipe 35, such as a bellows, is preferably bendable in order to accommodate for manufacture variations when securing or mounting the flexible heat pipe 35 to the first and second members. The flexible section 38 is preferably manufactured from a corrugated metal product, such as stainless steel or aluminum. As those skilled in the art will recognize, the heat transport system may be used in many other applications without departing from the spirit and scope of the present invention. For example, the heat transport system may be used in conjunction with capillary-pumped loops (CPL) or loop heat pipes (LHP). According to the invention, the apparatus for transferring heat in a spacecraft allows heat from internal equipment to be transported to the radiator of the spacecraft. The system provides a cost effective system that allows for greater use of pre-built production hardware. The system also facilitates manufacturing of the spacecraft by alleviating assembly misalignments when securing heat pipes to the shelf and radiator.

Claims: An apparatus for transferring heat in a spacecraft, comprising: a flexible heat pipe (35) having a first section (36), and a second section (40); a first member (32) of the spacecraft coupled to the first section (36) of the heat pipe (35); a second member (23) of the spacecraft coupled to the second section (40) of the heat pipe (35), wherein the first member (32) of the spacecraft being in a rigidly fixed relationship to the second member (23) of the spacecraft; characterized in that said heat pipe (35) has a flexible section (38). The apparatus of claim 1, characterized in that the first member (32) comprises a plug-in module. The apparatus of claim 1 or 2, characterized in that the first member (32) comprises a shelf. The apparatus of any of claims 1 - 3, characterized in that the first member (32) comprises a heat pipe. The apparatus of any of claims 1 - 4, characterized in that it further comprises electronic component (34) in thermal communication with the first section (36) of the flexible heat pipe (35). The apparatus of any of claims 1 - 5, characterized in that the second member (23) comprises a heat pipe. The apparatus of any of claims 1 - 6, characterized in that the second member (23) comprises a radiator (20). The apparatus of any of claims 1 - 7, characterized in that the second member (23) is in thermal communication with a radiator (22). The apparatus of any of claims 1 - 8, characterized in that the flexible section (38) comprises a corrugated metal. The apparatus of any of claims 1 - 9, characterized in that the flexible heat pipe (35) has a heat transfer medium disposed therein. A method of using a flexible heat pipe (35) for transferring heat in a spacecraft, comprising the steps of: providing a flexible heat pipe (35) having a first section (36), a second section (40), and a flexible section (38); coupling the first section (36) of the flexible heat pipe (35) to a first member (32) of the spacecraft; coupling the second section (40) of the flexible heat pipe (35) to a second member (23) of the spacecraft rigidly fixed with respect to the first member (32). The method of claim 11, characterized in that it further comprises the step of coupling the first section (36) of the flexible heat pipe (35) to an electrical component (34). The method of claim 11 or 12, characterized in that it further comprises the step of communicating heat from the second member (23) to a radiator (20). A satellite, comprising: a radiator (20, 22); and at least one electronic device (34); characterized by a heat transfer device including said apparatus of any of claims 1 - 10.

Inventors: DROLEN BRUCE L, ESPOSTO DAVID B, FLEISCHMAN GEORGE L, ITO CALVIN H, DROLEN, BRUCE L., ESPOSTO, DAVID B., FLEISCHMAN, GEORGE L., ITO, CALVIN H.
Applicants: HUGHES ELECTRONICS CORP, HUGHES ELECTRONICS CORPORATION
Application year: 1996
Main classification: B64G1
IPC codes: B64G1