Patent Application
20240247877
This invention relates to mechanical construction of lightweight, heat spreading structures, and, more particularly, to novel systems and methods for lighter, rapid, reliable assembly of isothermal truss plates, and truss plate assemblies providing multi-functional structures to support components and carry mechanical loads while providing heat spreading for near isothermal conditions for devices, such as satellites, thermal radiators, and space payloads, and providing heat transfer (sinking) and mechanical support for devices, such as satellite instruments.
Heat transfer is the mechanism by which cooling systems maintain a cooler region within a hotter region. Heat transfer is also the mechanism by which energy is carried from points of generation such as electronics, environmental loads, or direct heating, or the like. Heat transfer is driven by a difference in temperature between a material at a comparatively higher temperature driving energy to a material (e.g., location or object) at a lower temperature to receive that energy. In all cases of heat transfer, the temperature difference between the high temperature region or object and the lower temperature region or object is a driving potential for the transfer of heat, whether linear or non-linear in effect.
Typically, heat transfer deals with the resistance to hear transfer, the ability to move energy, through various materials, spaces, and so forth. The study of radiation, conduction, and convection seeks to identify the controlling parameters that govern the relationship between the temperature differences, heat transferred, material properties, distances, areas, and the like. Thus, in general, it is desirable to minimize the thermal resistance in order to maximize heat transfer from a region of higher temperature to a region of lower temperature. Similarly thermal resistance is to be maximized in order to minimize heat transfer. To the extent that thermal resistance is reduced, more heat may be transferred with a comparatively lesser temperature difference.
Electrical equipment has always required consideration of heat transfer to remove the heat generated by electrical resistance losses. Likewise, in systems such as satellites, spacecraft, and the like, the importance of maintaining low temperatures in certain equipment, such as sensors creating or recording images, and the like may require unique combinations of temperatures and thermal resistance.
Meanwhile, mechanical connections and distances required to remove heat may be substantial. Moreover, structural requirements for mechanical support may be substantial, requiring support against the ‘g-forces’ or acceleration forces of launch, transportation, and other movements. In fact, heat transfer and mechanical support are often at odds, wherein what is good for one is poor for the other. The result is tradeoffs that poorly serve one or both. It is important to keep components (electrical, mechanical, etc.) within their operating temperature range to ensure high reliability.
Finally, space is not without traffic of particles and various objects, within a broad range of sizes, from dust to satellite to asteroid sizes. These may be either naturally occurring or man-made. Space junk, small meteoric objects, and other projectiles may penetrate a surface of a satellite, permanently disabling mechanical, fluid, electrical, and other systems contained therein.
Thus, it would be an advance in the art to develop a spacecraft structure with a more effective heat transfer system, particularly one that would be adaptable to satellites to enable a resilient space system. It would be an advance to provide reduced thermal resistance within panels and between assembled panels, permitting temperature differentials less than are presently known in the art of satellite, and even less than those of many earthbound systems.
It would be a further advance in the art to create a comparatively strong structural support system with integral heat spreading, compared to prior art systems of equivalent weight in satellites and earthbound systems. It would be a further advance if such a system would support robust heat transfer, having comparatively better heat flux per degree of temperature differential than prior art satellite systems of comparable weight. It would be a further advance if such a system would support robust heat transfer, having comparatively better heat flux per degree of temperature differential than prior art satellite systems of comparable weight. It would be a further advance if such a system would support robust heat transfer in multiple directions to provide a uniform satellite temperature and tying system thermal mass together.
It would be a yet further advance to provide redundancy against failure in cases of mechanical damage, such as penetration by space debris or other objects. This could be significantly more valuable than earthbound systems, where such protection is not required at comparable weights to those of satellites.
Measuring, marking, locating, drilling, potting, inserting anchoring mechanisms (e.g., nuts, threads, blind holes, and so forth) of various types are not only time consuming, but require precision. Failures, errors, variable tolerance stackups, and the like present substantial risks to partially assembled hardware. For example, fasteners may be secured in holes or apertures in close proximity to heat pipes, or heat pipe strips. With the standard approach to stacking tolerances, it is possible that such may cause sufficient misplacement, misalignment, or improper registration of any particular component to cause damage, or at a minimum require extensive measurement time and extra equipment.
This can be very damaging when holes are drilled where fasteners are to be attached, most dangerously near heat pipes in systems in accordance with isothermal, structural panels. If a heat pipe is punctured, it is ruined. Thus, rather than completing assembly, one must destroy or at least deconstruct and repair such a partially assembled unit. Also, such failures may not even be recognized until final testing.
Honeycomb panels as described herein may be used in various standard shapes. They may be used with comparatively short thicknesses and comparatively larger wall thicknesses of the honeycomb in order to carry more heat between components bonded to either end of each honeycomb filler material. Meanwhile, weight or mass is critical inasmuch as the many suitable applications for an apparatus in accordance with the invention are for satellites where minimum weight is at a premium, while ready heat transfer is essential.
By placing fasteners through holes in an outer skin, one may self-tap or thread in fasteners. Fasteners may be potted into place or a material may be potted into a drilled hole in order to anchor a fastener that may protrude outward to receive an attachment. For example, a threaded shaft may protrude through a skin in order to anchor a component with a nut on that shaft. However, time, precision, steps, tolerance stackups, and the like all cause a high risk of waste, particularly for errors late in the process of assembly.
It would be an advance in the art to avoid drilling altogether, especially late into any assembly process, or worse, during actual use as a mounting system.
A means is needed for rapidly aligning (registering) individual components with one another in order to assure proper clearances and tolerances exist to separate possible puncturable heat pipes from other fasteners for mechanical securement of components (such as electronic equipment and the like) that may be mounted on a truss plate in accordance with the invention.
Thus, it would also be an advance in the art to simplify assembly to require less measurement and more pre-set registration structures to hasten, simplify, and render more precise the fitting together of components.
It would be an advance in the art to combine the above panel assembly advances with improved methods for connecting panels within into a structure assembly. This advance makes a reliable thermal connection between bonded panels for reduced thermal resistance, reduces the number of parts, reduces bolted connections, and reduces overall mass of a typical isothermal structure assembly compared with prior methods.
In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including modular thermal truss plates that may be configured to carry heat in multiple directions. Meanwhile, a combination of framing around a central layup of such a plate or panel may provide mechanical or thermal connections to other plates, and to a structure, such as a satellite frame, needing to support thermally active equipment such as electrical equipment.
In certain embodiments, walls, formed of skins (either composite layers or metal) sandwiching a flat thermal heat pipe or several flat thermal heat pipes therein may be combined by bonding them to a honeycomb, metal core. The core provides structure and additional thermal paths between the skins, and can conduct heat between multiple walls. Each of the walls, being a sandwich of an external skin layer on each side of a bed or bank of flat heat pipes capable of passing heat excellently in one direction. In other embodiments, the core contains a grid of stacked, flat heat pipes to provide heat transfer in two directions. In some embodiments, there may be one layer of heat pipes going in a specific direction, and in other embodiments, there may be grids of heat pipes going in two directions.
Within the panel, heat may be transferred in three dimensions. By placing each of the walls in a bonded relationship sandwiching the thermal core, such that each of the walls has a preferential heat transfer direction orthogonal to the other, heat may be transferred in three dimensions. Heat may transfer in and out of a panel, or wall. Heat may pass along the heat pipes in one or two directions. Heat may pass through the conducting core to the opposite wall. Heat may be transferred to an adjacent panel through one of the adjacent edges (either bonded or bolted connections). Heat may then be conducted in a preferential direction orthogonal to that of the first wall.
By providing multiple flat heat pipes in a grid arrangement providing heat transfer directions orthogonal to one another, the apparatus or truss plate may be particularly robust and resistant to single point failures. This also enables good heat transfer between connected panels. It may function, although at a limited performance if one of the heat pipes fails or is damaged. In certain embodiments, the truss plate-heat pipes may be connectable to one another to create larger expanses. Thermally conductive framing materials and efficient bonded or bolted connections may provide excellent thermal conduction between adjacent truss plates.
Each truss plate-heat pipe may be formed of corrugated copper sheet spaced from an opposite piece of corrugated copper sheet by a mesh, such as an expanded metal or screen material that is stamped or otherwise formed into a corrugated screen. Thus, the corrugated screen or mesh spaces the corrugated metallic sheets (wick).
Meanwhile, appropriate joining methods (e.g., brazing, soldering, etc.) may bond corrugated mesh material to corrugated sheets in order to form a truss plate-heat pipe that has substantially increased stiffness and strength within the heat pipe. The mesh binds the two layers of metal sheet to one another to support higher internal pressures. Dimensional stability results, providing for pressure and temperature variations. Meanwhile discreet spaces exist for the traveling of a working fluid liquid phase, such as water or other liquid therealong. In a direction opposite travels a vapor phase of the working fluid through adjacent vapor spaces.
Typically, the vapor spaces are comparatively larger, and are located in the center between the trussed pair of adjacent copper or other metal sheets. Meanwhile, the mesh material also serves to support capillary action within the corrugations of the metal sheets. Also, larger spaces provided by the corrugated mesh provide vapor spaces between the metal sheets to pass vapor phase operating fluid in a direction opposite that of the motion of capillary action of the liquid phase of the operating fluid.
Some of the benefits of apparatus and methods in accordance with the invention include higher pressures for operation of the flat truss plate-heat pipe.
Because the individual walls or panels are compartmentalized within the honeycomb structure, they are less vulnerable to damage or individual failure and may be positioned with clearances therebetween to support hardware connections by fasteners penetrating through the layup of the panel. This fastener configuration provides the ability to mount components to either side, or both sides, of the panel.
Improved manufacturability results from the use of materials that can be readily manufactured for the sheets, the honeycomb, the fasteners, the panel-to-panel connections, the mesh, the closure portions forming the walls between the sheets, and so forth.
Testing by modeling has been done for heat transfer rates across a thermal control panel formed of multiple truss plate-heat pipes in a first thermal control panel, bonded to a honeycomb core, to another thermal control panel, in order to transfer heat across a sandwich thermal control panel. Heat transfer has been analyzed from one edge of a sandwich thermal control panel through to an opposite edge of the same panel and from within the panel to an adjacent edge. In both cases, temperature differences, and therefore effective thermal conductivity through the truss plates has shown to be very favorable.
By forming the truss plate heat pipe in grids, or banks, embedding each grid in a thermal control panel, and then bonding those panels together through a lightweight metal core, and assembly lattice with integral threaded fastener holes, results in improved pressure support, frequency response to vibration, temperature limits across the panels, tolerance to failure, static load support, proof pressure, burst pressure, and vacuum support against leakage, have all shown to be very favorable for extremely demanding applications.
It has been determined that outgassing from the truss plate may be minimized to meet very stringent requirements, in accordance with the invention by using space-grade materials. Cleaning, design life, mechanical and thermal interfaces, and mass totals appear to be within a reasonable range. The electrical connection and grounding requirements appear to be easily tractable.
Edge connection temperature differentials between sandwich thermal control panels adjacent to one another on or within a structure have shown to be well within operational values for many applications in terrestrial and space applications. Moreover, this advancement in light weight, bonded or bolted, the conducting frames in which the truss plates are mounted may also improve heat transfer to and from the panels.
Meanwhile, structural stiffness of the sandwich thermal control panel is substantial due to the stiff thermal control panels multi-functional panel construction and bonded panel-to-panel connections. Clearances at the intersections of the truss plate heat pipes provide locations for penetrations through each panel in order to mount hardware there against. These are integral to the assembly lattice. Thus, mechanical support as well as thermal support are provided in a single panel for mounted hardware.
Current thermal computer models, using the dimensions and properties of the materials of the panels, demonstrate that temperature differentials across one truss plate may be as little as 4.5 degrees kelvin, and less than 3.5 degrees on a mounting surface given a 56 W heat load. Similarly, the temperature drop between adjacent, interconnected panels has been demonstrated to be less than 2.5 degrees kelvin for the same heat loading.
In some embodiments, truss plate heat pipes in accordance with the invention may operate across a range from about −30 degrees Celsius to about 65 degrees Celsius and the panels are designed to survive −40 degrees Celsius to about 75 degrees Celsius and above with a single working fluid, and a single structural design. Accordingly, the specific thermal conductivity of a truss plate in accordance with the invention appears to be on the order of greater than 1 watt per meter degree kelvin per kilogram per cubic meter, with a specific stiffness on the order of greater than 13 mega Pascals per kilogram per cubic meter. This compares very favorably to other conventional materials, including aluminum, beryllium, copper, and the like. Thus, the specific thermal conductivity is better than that of pure metals, of comparable specific stiffness.
In certain presently contemplated embodiments, a composite, or metal material at the outermost surface of each panel, or wall, may be on the order of 30 thousandths of an inch, with copper corrugated to have a total thickness on the order of 66 thousandths. The vapor space typically takes about 100 thousandths. Thus, the total wall thickness is on the order of 232 thousandths. The core, honeycomb, lattice, heat pipe configuration makes up the center portion of the panel. A 0.5 inch thickness of honeycomb core is oriented to conduct heat along the lengths of the honeycomb cavities between a pair of walls. The core is bonded by a thin layer of epoxy positioned between the innermost surface of one wall and each of the core components. Likewise on the opposite side of the honeycomb core a thin layer, on the order of about 5 thousandths thickness, bonds the honeycomb core to the opposite wall.
As a means to maintain the structural and thermal performance of each thermal truss heat pipe, the corrugations on the outside thereof (e.g., the face thereof that contacts the composite skin on the respective wall) may be filled with a suitable polymer. It has been found that a polymeric material may be smeared in and screeded off to fill the furrows or grooves in the outside surface of the corrugated metal sheet.
In one embodiment, copper is used in 3.35 inch widths and corrugated to sandwich within two such sheets a quantity of copper mesh. The overall thickness of the thermal strip formed of the copper spaced apart by copper mesh is typically on the order of 0.170 inch total thickness. These chambers or thermal strips may be formed in lengths suitable for extending across a particular truss plate. In one configuration, 20.8 inch lengths are suitable for the longer modules. A 12.5 inch length is suitable for those near the edges, which must provide clearance for openings handling cables and other lines that must pass through the panel.
The sandwich thermal control panel has two outer skins. Between each pair of outer skins lie plate-like heat pipes, or several truss plate heat pipes laid out side by side. Each of those truss plate heat pipes, since it is corrugated, relies on an end wall or end rail fitted to the corrugated shape and brazed to seal the end of the truss plate heat pipe.
Likewise, side walls or side rails fit into the outermost or nearby corrugation of each metal sheet in order to be brazed or otherwise bonded to seal the side edges or lateral edges of each of the thermal strips. An aperture in the end wall or end rail receives a tube that may be brazed thereinto in order to act as a vacuum port for evacuating and filling each of the truss plate heat pipes after fabrication.
In order to provide improved dimensional stability, truss plate heat pipe modules are provided along with spacer material on the outer skin. This provides spacing in the region between adjacent truss plate heat pipes, and in regions of the panel extending outside of the truss plate heat pipes, such as at the corners of the layup that will form each wall of the thermal control panel.
The skins may be formed of a prepreg fabric, such as a 140 GSM plain weave carbon fabric. One suitable material is the M55J material from Toray. This has a strength over 580 KSI and a modulus of elasticity of about 78 MSI. The skins may also be metallic. Framing for the truss plate may be made using aluminum extrusions or castings such as may be fabricated from 6061 aluminum or other thermally conductive metallic material. These may be formed to mate with the layup of two walls bonded to a core. The intimate contact for thermal and mechanical purposes provides a structurally sound and thermally effective sandwich thermal control panel.
In certain embodiments, the truss plate may be provided with fasteners formed through the layup, thus penetrating both walls and the intermediate core. Typically, the spacing therebetween is on the order of 10 cm in order to accommodate the width of each thermal strip. Meanwhile, in the orthogonal direction, the spacing may be about 5 cm or other suitable dimension. Accordingly, fasteners, such as bonded rivets, bolts, screws, or the like may be used to connect devices to the thermal control panel.
In certain embodiments of a system and method in accordance with the invention, a lattice or jig is provided for assembly, and remains a part of the apparatus permanently. The jig is somewhat planar in shape, having two comparatively large orthogonal dimensions “in plane,” and a substantially “comparatively smaller” (compared to the planar dimensions) dimension “normal” (perpendicular, orthogonal) to the planar dimensions.
The jig or lattice looks something like a grid of thin walls or legs defining polygons. The polygons may be rectangular with the sides thereof (legs, walls) being what one may consider ribs in the lattice. Each polygon defines an opening configured to receive a fitted insert (fitted meaning shaped “in-plane,” but typically having a lightweight, honeycomb cross-section when viewed “normal” to plane, where normal means perpendicular). Additionally, the lattice registers the heat pipes in a straight or grid configuration.
Each insert and heat pipe may ultimately be bonded to a skin on one or more planar sides or faces of the lattice. Spacing the skins apart with the inserts in this way provides structural strength, stiffness, and thermal conductivity. The legs or walls meet at vertices, some sharp and others provided with a pillar or vertex pillar having a longitudinally threaded hole through its center (in plane). Each pillar extends perpendicular to the faces of the lattice. Each threaded hole, or aperture, in a pillar may later, after assembly of the apparatus, receive a fastener to secure a component to the panel, or outer skin, by simply bolting, screwing, threading, otherwise fastening, such component to a built-in threaded hole or vertex pillar. The outer skins are perforated in precise registration with the threaded apertures in the pillars of the lattice or jig. The fastener locations can either be a typical 5 cm×5 cm arrangement, or a custom, specific arrangement.
Meanwhile, during assembly, the apertures in the pillars may receive threaded pins to serve as registration positions for registering and assembling other components, none of which can thereby be interfered with or damaged by a later-inserted fastener or drilled hole straying from the center of the particular pillar.
Inserts of honeycomb material may be of multiple types, but may be reduced to two. The honeycomb inserts may be shaped to fill the entire distance (skin-to-skin) through the lattice, or may be shorter in order to merely fill the distance from a heat pipe strip to a non-contacting outer skin on a face opposite to that skin serviced by and in contact with that particular heat pipe strip.
Accordingly, to accommodate the pillars the inserts may have corner concavities shaped to fit around the pillars in order to glide into position. The inserts may have a slight interference fit in order to provide frictional retention, or may secured by other mechanisms, such as glues between walls of the lattice and the walls of the inserts, backing boards (in plane, or parallel to plane) that support or provide a supporting surface for the inserts to be aligned with the lattice, or the like.
The lattice or jig is not removed but remains as part of the mechanical structure in operation. In fact, the jig or lattice has certain walls or legs that have relief either on a top side or a bottom side thereof. These relief spaces receive the heat pipes, or heat pipe strips. Thus, a typical stack up from one face to the opposite face would be an outer skin followed by an adhesive layer against which are contacts by both honeycomb inserts and heat pipes. These heat pipes are all of one orientation in any array. An array corresponding to one skin or face is then orthogonal to those of an opposite skin or face.
In some arrangements, arrays of heat pipes, or heat pipe strips, will thus run orthogonally to, and in contact with, each other at each crossing point where one set of heat pipe strips crosses another. At that point intimate contact, typically aided by an adhesive layer by bonding, adhesive greases, or the like may maintain suitable thermal conductivity therebetween. Again, behind each heat pipe (opposite the contacted skin face) fits a “short” insert conducting heat and providing mechanical stability between that heat pipe strip and the opposite, non-contacted, outer skin.
Bonding layers may exist to aid structurally and thermally between inserts and outer skins in contact with one another, while other bonding may fill in and secure the heat pipe strips into the corresponding, fitted, relief regions into which each is received by the jig or lattice. Short, backing inserts are needed only between a heat pipe strip and its opposite, non-contacting, outer skin.
Through holes (extending full thickness, skin-through-skin) may act as “access apertures” for running wires, cables, tubes, and so forth from one face of an apparatus to the opposite face thereof, from inside to outside an apparatus and vice versa. These may be customized as required and may alter the heat pipe grid arrangement in some embodiments.
More rapid and precise assembly is effected by embedding a jig or lattice, as well as protecting against damage during assembly. Drilling after assembly is fraught with risk. An additive sum of tolerances in various components runs the risk of puncturing a flat heat pipe, destroying the operation of the entire apparatus. These apparatus and methods disclosed herein may register all components with respect to the jig (lattice, template) that permanently remains part of the structure. Thus, every component can be registered (aligned, positioned, oriented, etc.) precisely with respect to a single, solid, rigid lattice that serves as an assembly jig and later as part of the structure.
Registration means positioning at, against, or with respect to a predetermined “datum,” typically represented by a physical edge, wall, shelf, boss, or other rigid artifact that readily indicates a precise, repeatable location. A most effective datum receives a contact by a component to be registered and affirmatively stops it from moving further (past the artifact).
Registration may occur in one or more directions (dimensions). Here, registration of the heat pipe strips occurs in at least two dimensions as each one fits into a relief region extending normal to (perpendicular to the planar direction of) the lattice, bounded on each long edge by the lattice itself. In some instances, endwise registration can be done with or without an affirmative “stop” by aligning ends of those strips with or within corresponding planar edges of the lattice.
In one example, an apparatus operable as a lightweight, isothermal, structural mounting plate, may include a lattice, flat heat pipes in one direction or in a grid, and honeycomb spacers, all within outer skins serving as “outermost layers,” or “outermost fiber structures,” for strength and stiffness, mounting surfaces, and thermal heat sinks. The lattice, defines first and second faces each defining a plane constituted by two dimensions, formed of polygons, the polygons being defined by walls extending between vertices of the polygons and extending in a “through-plane” direction defining a lattice thickness between the first and second faces, the lattice containing pillars at selected ones of the vertices provided with pre-threaded holes extending thereinto in a through-plane direction.
A first plurality of flat heat pipes is recessed into the first face to extend in a first planar direction, and a second plurality of flat heat pipes recessed into the second face to extend in a second planar direction orthogonal to the first planar direction. Inserts, are thermally conductive in the through-plane direction, lightweight in cross-section in the planar direction, and fitted into the polygons.
Outer skins are registered to and bond to the lattice, inserts, and flat heat pipes, by aligning mounting holes therein with the pre-threaded holes in the pillars. Bonding material may be applied to increase thermal conductivity and mechanical strength between the first and second plurality of flat heat pipes and the outer skins. In some locations a thermally conductive grease may substitute for thermal transfer, but not for structural strength.
Bonding material may be applied between the first and second pluralities and the lattice, and between the first and second pluralities. It may be applied between the lattice and the outer skins, as well as between the inserts and flat heat pipes and between the inserts and the outer skins.
The inserts are contemplated to have a honeycomb cross section “in plane.” The lattice may be provided with relief channels sized to receive the flat heat pipes in the first and second faces, the relief channels constituted by selected ones of the walls that do not reach completely across the lattice thickness.
The lattice benefits structurally and in precision if fabricated as a single, continuous, monolithic piece, such as by one of machining or casting. In other instances, the lattice is constructed of large segments located within the panel by pins to enable matching or for some other purpose. Pins are capable of registering the outer skins with the lattice and the pre-threaded holes by being selectively securable and removable from the pre-threaded holes in the pillars. Thus, the outer skins and their mounting holes are all aligned in all dimensions, fully registered by location, at once.
A frame comprising rails surrounds the edges of the outer skins, which may also sandwich or contain peripheral inserts fitted between the outer skins, the lattice, and the frame. Bonding material rapidly secures the first and second pluralities of flat heat pipes, each one of the flat heat pipes having a length greater than a width thereof and a width greater than a thickness thereof, into a relief channel recessing into the corresponding first or second face of the lattice. Inserts fit into corresponding ones of the polygons to fill the entire thickness of the lattice with at least one of insert material, flat heat pipe material, bonding material, and a combination thereof. The outer skins are registered directly with the lattice by the pre-threaded holes in the pillars, and bonded to the first and second faces of the lattice.
In a method of fabricating the apparatus, one may begin by providing a lattice, generally planar in configuration defining first and second lattice faces and a lattice thickness therebetwen, the lattice comprising walls extending orthogonally to the planar direction (defined as the lattice thickness direction) as well as extending and connecting “in plane” at vertices defining spaces therebetween, the lattice being capable of operating as an embedded jig for assembling a thermomechanical panel providing structural support and heat distribution for devices secured thereto.
Then one can use first and second pluralities of heat pipes as strips, each individual heat pipe thereof having a strip length multiple times a strip width, and a strip width multiple times a strip thickness. Any polygons not crossed by a strip will receive an insert passing from one outer skin to the other. Any polygon crossed by a strip receives a “short inserts backing up the strip, which strip is in direct bonding contact with a corresponding outer skin. Each insert extends as a collection of interconnected solid walls in the lattice thickness direction and having a matrix of polygons as a cross-section “in plane.” Think honeycomb or the like in cross section.
One method places each heat pipe of the first plurality into a corresponding relief region (relief channel or recess extending across the lattice by shorter walls in the polygons). These will be on each opposite lattice face and within the lattice thickness, each heat pipe spanning multiple spaces and crossing multiple legs of polygons. Likewise, each heat pipe of the second plurality into a corresponding relief region proximate the second lattice face and within the lattice thickness, each flat heat pipe of the second plurality spans multiple spaces and crossing multiple legs as it extends orthogonally, in plane, with respect to the first plurality. Each insert fits into one of the spaces and may benefit from bonding to an outer skin on at least one of the lattice faces.
Bonding material may be applied between the walls and a corresponding outer skin, likewise between each heat pipe and the lattice, and even bonding the first plurality of heat pipes to the second plurality of heat pipes at intersections thereof. In some embodiments, the strip lengths are all equal.
Each of the inserts may be individually positionable in at least one of the faces of the lattice after securement of all the strips into the relief regions of the lattice. For example a first outer skin bonds to selected ones of the strips and of the inserts at one face of the lattice. Also a second outer skin, on an opposite face bonds to other ones of the strips and of the insert at a second face.
One method for assembling a lightweight, isothermal, structural mounting plate, the method includes fabricating a lattice, having first and second faces, of polygons, defining a planar, that is, “parallel to a plane,” direction in two dimensions, the polygons defined by walls extending between vertices of the polygons and extending in a “through-plane” direction a lattice thickness, at right angles to the planar direction, the lattice containing pillars at certain vertices provided with pre-threaded holes extending in the through-plane direction.
To it are provided inserts, thermally conductive in the through-plane direction and fitted to the polygons, flat heat pipes, and bonding material. Bonding a first plurality strips, each constituting one of the flat heat pipes having a length greater than a width thereof and a width greater than a thickness thereof, into the first face of the lattice occurs on a first face of the lattice, whereas bonding a second plurality of strips is done into the second face of the lattice, opposite the first face. They extend lengthwise orthogonal to the first plurality.
Positioning inserts into corresponding ones of the polygons to fill the entire thickness of the lattice can be done from either face. However, one may also bond in all the strips (flat heat pipes) into the lattice, followed by adding the insert material from either side as necessary.
Outer skins capable of covering the lattice are provided with through-holes corresponding to the pre-threaded holes in the pillars. Thus, following registration with each other by pins extending temporarily from those pre-threaded holes in the pillars is followed by bonding the outer skins to the first and second faces of the lattice as well as any inserts or flat heat pipe strips. One may then mount mechanical, electrical, optical, or electromechanical devices to be mechanically supported by and thermally conductive to at least one of the outer skins by fasteners threaded through the mounting holes of the outer skin and into the pre-threaded holes in the pillars.
Pre-machined bond frames can provide a rapid way to configure the panels into a structure to support mechanical components, transfer heat between isothermal panels, and provide a lighter, and resilient connection. This enhanced isothermal panel and structure hardware and method significantly improves assembly time, reduces risk, reduces mass, while creating resilient structures.
The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which:
It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.
The basis of the invention is the truss plate heat pipe, 10. This unit provides the primary means for spreading heat. The internal mesh truss structure rails, and end fittings, 9, 10, 11, 12 combine to make the structurally and thermally capable truss plate heat pipe. In one presently contemplated embodiment, an apparatus 10 may include rails 11 such as a top rail 12a, bottom rail 12b, a joining rail 14 and an opposite joining rail 16. In general, these may all be referred to as rails 11, or may be referred to individually in their specific roles as rails 12a, 12b, 14, 16.
Referring to
Typically, a layer of bonding material, such as a B-staged epoxy material, thermoplastic, thermoset plastic, spreadable glue, or the like may be spread on one side of a skin 46. The core 18 may then be bonded to the skin 46. Opposite the first thermal control panel 19, 20 a second wall may be bonded likewise to the core 18. Together, the two skins and their intervening small core 18 form a layup 22. The layup 22 is the internal portion 22 (between the outer skins 46) of the truss plate 10.
The external portion, or the edge portion, surrounding the sandwich of layup 22 and outer skins 46 of the thermal control panel 10 is a frame 24. The frame 24 is formed of the various rails 11, and specifically a top rail 12a, bottom rail 12b, edge rail 14, and another edge rail 16 opposite the first edge rail 14. These rails 11 are fastened together and to the layup 22 to form a frame 24 around the layup 22. The rails 11 may be attached by fasteners to one another to form the frame 24.
Thus, the frame 24 with its contained outer skins 46 and layup 22 provides thermal heat transfer properties and mechanical stiffness and strength properties suitable for the combined functions of thermal management and mechanical support. For example, strength, distortion, displacement, vibration frequency response, and the like may all be controlled by the combination of the truss plate heat pipe layup 22, outer skins 46, and frame 24 forming the sandwiched thermal control panel 10.
Each sandwich thermal control panel 10 may be provided with comparatively wide apertures 26 for passing wires, cables, material transport lines, tubes, and so forth through the truss plate 10. Thus, devices operating exterior or on either side face of the sandwich thermal control panel 10 may exchange data, electric power, fluids, or the like with other devices or components on the opposite side of the sandwich thermal control panel 10. The apertures 26 may be referred to as access apertures 26 for lines and other service members to pass through.
One of the functions of a sandwich thermal control pane 110 is to support devices structurally and provide an isothermal mounting and cooling surface. Accordingly, an array of holes 28 may penetrate through an individual wall 20, or even through the entire layup 22. Fasteners such as screws, bolts, rivets, bonded rivets, or the like may penetrate through the mounting apertures 28, or simple apertures 28, in order to fasten any device or component to the layup 22. Thus, the sandwich thermal control panel 10 performs as a structural mounting substrate for devices connected at the apertures 28.
The thermal control panels 20 contain other components performing two-phase fluid heat and mass transport processes. Accordingly, the interiors must be evacuated through tubes 30. Typically, the tubes 30 are metallic and brazed to metallic internal components of the layup 22, and specifically inside the walls 20. The tubes 30 may extend out through the frame 24 in order to provide access for evacuation. After evacuation, followed by refilling with a two-phase working fluid, the tubes 30 may be crimped and cut off in a single cold-welding, crimping process, or the like.
Meanwhile, each of the rails 11 may be provided with an outer flange 32 on each side thereof. The flanges 32 are positioned to capture the thermal control panels 20 therebetween. Likewise, a spacer 34, which may also operate as a flange 32, is sized to fit between adjacent thermal control panels 20 of a single sandwich thermal control panel 10. Thus, the distance between each flange 32 and adjacent spacer 24 is sized to receive and bond therein a thermal control panel 20 of the layup 22.
In certain embodiments, it may be structurally advantageous to form gussets 36 at certain locations on each rail 11. Gussets 26 provide structural strength and improved section modulus in order to support fastening of the frame 24 to an underlying structure, such as a satellite, a frame, an electrical box, or the like, as well as serving to connect various rails 11 to one another in adjacent sandwich thermal control panel 10. For example, in the illustrated embodiments, gussets 36 may be formed between orthogonal, plate-like ears 39 or attachment extensions 39 of each rail 11.
The apertures 38 formed in a particular rail 11, such as the rails 12, 14, 16 may receive fasteners to mount the sandwich thermal control panel to another device or to another sandwich thermal control panel 10. These apertures 38 may result in fasteners secured therein applying forces to the rails 11. Resisting those forces requires increased section modulus, depending on the values of those forces, and thus the gussets 36 may maintain the “ear portions” 39 in fixed and rigid relation with respect to one another.
Referring to
Referring to
In the instant embodiment, each truss plate heat pipe 40 may include a spacer core 42 assembled on or in each wall 20. The spacer 42 operates something as a template and spacer to space apart the outer skins 44.
The sheets 44 are corrugated, and may typically be formed of an excellent thermal conductor such as copper. Meanwhile, the outer skin 46 of the wall 20 is a composite material. Thus, between two outer skins 46, is a truss plate heat pipe 40. A skin 46 serves as a structural strength component on each side of the truss plate heat pipes 40 formed of copper sheets 44 or other sheets 44 of some other metal, polymer, or the like.
A skin 46 formed of suitable material may be laid down and a spacer 42 may be placed thereon. The spacer 42 has portions in which its own material, typically a polymer or honeycomb, is placed, and other places, locations, or regions where there is a partial or total evacuation or lack of material. In these evacuated or empty portions, are placed the strips 40 formed of pairs of sheets 44.
Between pairs of sheets 44, a vapor space 48 or simply a space 48 provides a region for passage of the vapor phase of a working fluid captured within the strip 40 formed by adjacent pairs of sheets 44.
One may note that the upper thermal control panel 20 contains a truss plate heat pipe 40. Likewise, below, the edges of the truss plate heat pipes 40 are not shown, but simple terminate schematically at the spacer 42. However, the edges of adjacent sheets 44 in a particular strip 40 are indeed bonded together as will be described hereinafter. However, the orientation of the bottom set or bank of strips 40 is orthogonal to the orientation of the bank of truss plate heat pipes 40 on the opposite side of the inner core 18. Thus, heat transfer may occur much more readily along the length of a truss plate heat pipe 40 than crossways across the width thereof. The spacers 42 create effective thermal resistances or thermal gaps between adjacent strips 40.
Referring to
Referring to
The mesh 50 at the locations where it contacts the sheets 44, at their internal extremities of their corrugations, also defines the liquid space 52 or the spaces 52 carrying liquid. Thus, the vapor spaces 48 carry vapor in one direction, from a comparatively hotter region where the vapor is formed, back to the opposite end or elsewhere of each strip 40, where the comparatively cooler temperatures condense the vapors in the vapor space 48 to liquid. The liquids, then move by capillary action through the spaces 52, returning to be vaporized again at the comparatively hotter end of the truss plate heat pipe 40.
As a practical matter, the sheets 44 may be brazed together by placing walls 54 or rails 54 captured within the last, or near the last corrugation within each sheet 44. The rails 54 or walls 54 are sized to fit within the corrugation dimensions where they may be bonded by brazing or the like. It has been found that a silver and copper eutectic operates as a suitable brazing material, drawing into the small spaced between the mesh 50 and sheets 44 when melted.
Likewise, the ends of the truss plate heat pipes 40 need to be sealed. Each truss plate heat pipe receives an end wall 56 or rail 56 fabricated to match the shape of the corrugated sheets 44. Thus, the end walls 56 are fitted in between the sheets 44, within the internal corrugations or cavities of each of the sheets 44, where these rails 56 also may be brazed.
Referring to
By grasping the handle portion 55, a technician may place each rail 54 within the corrugation where it must fit, and also rotate it or manipulate it in order to engage the rail 54 with the corrugation of the sheet 44 opposite. Thus, for example, one may place the rail 54 in the outermost corrugation of the bottom sheet 44b, and then manipulate the handle 55 fit the rail 54 into the outermost corrugation corresponding thereto in the upper sheet 44a.
Referring to
For example, each of the end rails 56 may be provided with lands 60 and grooves 62 matching the corresponding corrugation grooves 61 and lands 63 of the sheets 44. Thus, the corrugations of the sheets 44 fit within the grooves 62. Meanwhile, the lands 60 fit within corrugations in the sheets 44. A key 64 is a portion of the end rail 56 shaped to fit within a key way 66 in the side rails 54. Thus, the key 64 fits in the key way 56, fixing the end rail 56 with respect to the side rail 54.
Once the entire strip 40 has been assembled with both sheets 44a, 44b, the side rails 54 and the end rails 56, the constituents may all be bonded together with a suitable brazing material and technique. The aperture 58 is sized to receive a tube extending thereinto. The tube 30 may be brazed into the aperture 58 just as the mesh 50 to the sheets 44, or each corrugated sheet 44 is brazed to the rail 54 or sidewall 54, and the end rail 56 or end wall 56. Upon completion of brazing, and cooling of the strip 40, a vacuum may be drawn on a tube 30 in order to test the seal, and assure that the brazing has been complete and is leak tight.
Referring to
The truss plate heat pipe 40 is itself a truss. That is, the mesh 50 has been brazed to the sheets 44. The sheets 44 have a certain number of their corrugations spanned by the mesh 50. In one embodiment, the period of the corrugations in the sheets 44 is half that of the corrugations in the mesh 50. Thus, about half the corrugations internal to the truss plate heat pipe 40 are bridged by the mesh 50. Others may remain completely unobstructed and open. Since the mesh 50 is a mesh, the corrugations are not completely closed, but rather the liquid space 52 or the corrugation 52 is simply bridged periodically by the mesh 50.
The mesh 50 also extends between the sheets 44. Thus, in bending, the sheets 44 may be thought of as tensile or compression members at the outermost extremities of the strip 40, while the mesh 50 spaces these sheets 44 apart from one another, thus creating a truss. Moreover, the sheets 44, being brazed to the mesh 50 are typically connected at every periodicity of contact with the mesh 50.
Thus, the center portion of each strip 40 is not at liberty to separate between the sheets 44. Rather, the sheets are maintained together at their distance apart throughout the strip 40. Pressure tests show that the brazed mesh 50 bonded to the adjacent or facing sheets 44 provides a substantial strength against internal pressures. Pressures of 6.5 atmospheres and more have been tested, without failure of the truss plate heat pipe 40. The mesh 50 forms a lattice work or truss lattice between the sheets 44.
Referring to
Nevertheless, it has been found that weight-sensitive applications may suffer in meeting their maximum weight limitations if the array 70 includes two orthogonal batteries 74, 76 of thermal truss plate heat pipes 40. Thus, in one presently contemplated embodiment, the single battery 74 is mounted within a single thermal control panel 20. Meanwhile, an opposite wall 20 in the same layup 22 includes the second battery 76 as its array 70.
It has been determined that the thermal conductivity of an aluminum honeycomb core 18 has sufficiently distributed contact, and sufficient cross sectional area, that even a thickness of half an inch between thermal control panels 20 straddling a core 18 provides sufficient heat transfer rates to meet the functional benefits provided by a sandwich thermal control panel 10 in accordance with the invention.
For example, heat transferred into any edge of a truss plate 10 will be transferred into a rail 11. For example, heat may be transferred from one joining rail 14 into the layup 22. Of course, the layup 22 includes two walls 20, each having a preferential heat transfer direction orthogonal to the other. Most of the heat will transfer most rapidly into the end of the batteries 74, 76 or array 70 that is in contact with the rail 11 where heat is being transferred into the layup 22. Of course, a certain amount of heat will also transfer into the opposite battery 76,74 and be transferred along the extent of the rail 11 where the heat is being added.
Meanwhile, heat may also be transferred directly through the skin 46 on the overall surface of a sandwich thermal control panel 10. For example, the surface of a layup 22 may have a device, such as powered electrical equipment connected thereto. Accordingly, the skin 46 passes heat through its thickness and directly into the sheet 44 of a truss plate heat pipe 40.
However, in transferring heat between and about sandwich thermal control panels 10, heat transferred in at, for example, a rail 11, such as a joining rail 14, will transfer easily into the ends of the thermal modules 40 or thermal truss plate heat pipes 40 that abut the rail 14. They will thus be able to transfer heat along their entire length, passing heat throughout their thermal control panel 20 on that side of the entire sandwich thermal control panel 10. Throughout the layup 22, meanwhile, those portions of one wall 20 that are comparatively hotter then the portions of an adjacent thermal control panel 20 on the opposite side of the core 18 will then transfer heat therebetween. Accordingly, heat travels comparatively rapidly along each of the truss plate heat pipes 40, but still sufficiently, once distributed, through the core 18 and into the strips 40 of an opposite wall 20 within the same layup 22.
In the foregoing manner, thermal objectives may be met, in any dimension. Notwithstanding the increased distance through the core 18, the increased resistance of the skins 46, and so forth, the honeycomb 18 presents a substantial and distributed heat transfer area. The working fluid within each of the thermal truss plate heat pipes 40 can pass quickly through the liquid spaces 52 and vapor spaces 48 thereof. Thus, distribution throughout the full area of one wall of a particular layup 22. One wall 20 thereof may then provide substantially increased area for heat transfer through the core 18 to the opposite wall.
Thus, heat may be transferred from a rail 14 across the layup 22 to an adjacent or opposite rail 16. That is, heat may be transferred from a top rail 12a to a lower rail 12b, or vice versa. Moreover, heat may be transferred from a side rail 14, 16 to one of the top rail 12a or bottom rail 12b in similar manner Moreover, heat may be transferred from a rail 11 of one sandwich thermal control panel, through the frame 24 of that truss plate 10 to the connected frame 24 of an adjacent truss plate 10, and then transfer through the second sandwich thermal control panel 10.
Referring to
Referring to
In some embodiments, the rail 16 may be formed to have angles that are orthogonal or non-orthogonal between the adjacent faces thereof. For design reasons, that angle may be something other than 90 degrees or a right angle. Meanwhile, the rail 12 may serve as a mounting rail, having one portion extending parallel to the flange 32, and supporting apertures 38 for fastening that ear 39 to some structural substrate, such as a satellite frame, aircraft frame, electronic rack, electronic housing, or the like.
In the illustrated embodiment, the non-orthogonal position of the ear 39 of the rail 16 with respect to the flange 32 thereof may provide for turning corners. Similarly, corners may be turned abruptly, even orthogonally if the ear 39 is exactly parallel to the flange 32 of the rail 16. This may permit access to fasteners through the apertures 38 to fasten into a corresponding side rail 14 of an adjacent frame 24 in an adjacent sandwich thermal control panel 10.
Referring to
Referring to
The illustration of
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Referring to
The illustrated embodiment, shown in
In the illustrated embodiment, the apertures 28 or mounting holes 28 also continue effectively as apertures 98 to pass completely through the apparatus 10. Technically, holes 28 are cut through the skins 46 in a grid pattern. That grid pattern is precisely replicated in the jig 90, where the holes 98 in it are formed (preferably by casting or drilling) precisely in the same grid pattern and threaded interiorly.
Lying across each face (e.g., a top face, bottom face, here, for the sake of discussion) will be heat pipes 40 or heat pipe strips 40, sometimes simply referred to as strips 40 having all the characteristics of heat pipes 40 discussed hereinabove. These 40 underlie each outer skin 46. The outer skins 46 provide mechanical structure, stiffness, dimensional stability, and an “outermost fiber” as understood in the case of any bending of an apparatus 10. The heat pipe strips 40 are laid out in an array 70 in a bonding relationship with the outer skin 46 corresponding thereto.
In order to provide improved assembly (faster, more reliable), more precise registration (alignment, positioning, locating in space) of each component, a lattice 90 operates as a jig 90 or template 90 for assembling the apparatus 10. However, unlike conventional jigs that may be used on an assembly table to position components, this lattice 90 or jig 90 is ultimately incorporated into the assembled structure 10, thereby providing both heat transfer, structural stiffness, and registration of a host of components.
Referring to
The lattice 90 is made up of ribs 92 or legs 92 as walls 92 between corners 94 or vertices 94. However, these legs 92 have three dimensions, and in particular a depth rendering each leg 92 or rib 92 a wall 92. These walls 92 thus provide shear strength and stiffness in bending out of the plane of the apparatus, as well as dimensional stability of the plane within the “planar directions,” defining a two-dimensional space. Each leg 92 meets other legs 92 at a vertex 94.ss
Vertices 94 are typically of two types. Some in the illustrated embodiment are formed at basically sharp angles, right angles. Others meet at a shared cylindrical pillar 96 as a vertex 94. These pillars are an improvement over prior assembly components and methods in that each of the pillars 96 is a cylinder of known dimension, which can be precisely produced by casting, machining, or other fabrication process well ahead of any assembly process for the apparatus 10. They can also be threaded or finished as thru holes at formation or afterward.
By thus providing a threaded aperture 98 down the center of each pillar 96, the apertures 98 may be precisely formed and positioned. Later, fasteners, or possibly pins, will fit through the apertures 28 and thread into those apertures 98. Holes 28, 98 need not be measured, located, marked, drilled, or tapped during assembly of the apparatus 10. Components are precisely fabricated to need only alignment or, more precisely, “registration” with each other, leaving no opportunity for damaging the strips 40 by drilling during assembly. That is, the jig 90, itself, is fabricated with a specific dimensionality, sizes of ribs 92 or walls 92, precise location of vertices 94, precise size and shape of the pillars 96, and precise location and threading of the apertures 98 in the pillars 96.
Assembly of components to the lattice 90 may be done with the lattice 90 vertical or horizontal. Held vertically, the lattice 90 can accept all components shown in order from the lattice 90 outward to the skins 46 and frames 24. Horizontally oriented, the lattice is best filled from one side (face), then rotated 180 degrees to fill remaining open spaces 93 the opposite face.
For example, during assembly, the lattice 90 may be laid on a surface, or may be set on a movable backing temporarily fixed to the lattice, or even slightly (removably) adhesive. A releasable adhesive may hold received inserts 100 thereinto. Inserts 100 fit into the spaces 93 between the ribs 92 or walls 92. The inserts are honeycomb shaped in cross section, where the cross section is taken in plane with respect to the apparatus 10.
Inserts 100 may typically be of two types. The inserts 100a are tall (comparatively, meaning compared to the shorter inserts 100b). These honeycomb inserts 100 are fitted into the spaces 93, polygons defined by the legs 92 or walls 92 (ribs 92 of the lattice 90). Wherever no thermal heat pipe 40 or heat pipe strip 40 passes through the lattice 90 from outer skin above 46 to outer skin below 46, an insert 100a spans that entire space 93 in the thickness direction. It may be bonded by adhesive, held by dimpled or inclusion types of detents, or held temporarily by any other suitable mechanism. Later, it may be secured permanently by a bonding material to the outer skins 46.
However, anywhere that a heat pipe strip 40 would interfere with a clear passage through a space 93 between adjacent legs 92 or walls 92 of the lattice 90, accommodation must be made for the heat pipes 40. To this end, variations in shape of the spaces 93 exist. For example, the pillars 96 at vertices 94 impose the need on an insert 18a for a corner concavity 102. Any pillar 96 that impinges into the space 93 between walls 92 will need to receive an insert 100a having a corner concavity to accommodate that pillar 96.
Meanwhile, however, inserts 100b in the illustrated embodiment have sharp corners at all vertices 94, lacking any interior pillar 96. Moreover, the shorter inserts 100b pass only between an individual heat pipe strip 40 opposite an outer skin 46 associated with that heat pipe 40. Thus, a short insert 100b provides a mechanically stiffening, structural filler and thermal conductor. It mechanically stiffens against collapse or distortion of both the heat pipe strips 40 and the outer skins 46, while conducting heat through the thickness direction of the apparatus 10.
To accommodate the thickness and width of heat pipe strips 40, the lattice 90 provides relief 104 by way of shortened walls 92 or reduced thickness or height (in the apparatus' 10 thickness direction; “orthogonal to plane”) of walls 92 extending between the outer skins 46. For example, part of the space 93 between opposing outer skins 46 is occupied by a heat pipe strip 40. That heat pipe strip 40 is in intimate contact through an adhesive 79 or other bonding material 79 as a bonding layer 108 to the corresponding outer skin 46. Opposite that outer skin 46 is a short insert 100b extending the remainder of the distance from that corresponding, intimately bonded heat pipe strip 40 toward the outer skin 46 on the opposing face of the outer skin 46 away from that heat pipe strip 40.
These relief regions 104 correspond to an array 70 of strips 40. For example, in the illustrated embodiment, the array 70 of strips 40 near the lower outer skin 46 may be thought of as an array 70a. The array 70 of heat pipe strips 40 above the lattice 90 may be thought of as the upper array 70b. As illustrated, the inserts 18a fit between the bonding material 79 on a back face of a strip 40 and the opposite, outer skins 46 with which the strip 40 has no intimate thermal and mechanical contact.
Thus, “short” inserts 100b back up strips 40 by contacting the bonding layer 106 of the opposing outer skin 46 not corresponding to the specific heat pipe 40 in question. Thus, during assembly, one might access each face (e.g., top and bottom) by standing the lattice 90 on edge or on one face and applying bonding strips 108 in the relief regions 104 corresponding to each face. The heat pipe strips 40 corresponding to each bonding strip 108 and its relief region 104 will all adhere to the lattice 90 (and each other wherever they cross).
One may then similarly place the heat pipe strips 40 corresponding to the opposite outer skin 46 by placing bonding strips 108 in the corresponding relief regions 104 on that face of the lattice 90 corresponding to this second array 70b of heat pipe strips 40.
As a practical matter, at those locations where heat pipe strips 40 cross one another, no spacers are needed. The bonding strips 108 provide intimate contact between the contacting heat pipes 40 in both arrays 70a, 70b.
At this point, the lattice 90 may be placed on a surface, such as a clean board, table, sheet, non-adhesive layer or the like in order to place inserts 100 into each face of the lattice 90. Each space 93 will be available from one face or the other of the lattice 90 in order to put in or insert one of the honeycomb inserts 100a, 100b. Again, in a space 93 across which no heat pipe 40 passes, a taller insert 100a may be inserted. In any space 93 that is basically a blind hole 93 because a heat pipe 40 truncates one side, then a short insert 100b may be installed. Again, inserts 100 may be provided with adhesive tacky contact materials to contact the legs 92, detents to engage the legs, or simply a slight interference (e.g., friction) fit in order to remain in place during assembly.
Empty contact spaces 110 exist in order to provide contact and heat transfer between the opposing arrays 70a, 70b. At a “center plane” of the apparatus 10, each heat pipe strip 40 corresponding to one outer skin 46 will cross all heat pipes corresponding to the outer skin at the opposite face of the apparatus 10, but will cross none of those in its own array 70.
In one presently contemplated embodiment, pins 112 or alignment pins 112 may be set up as registers or registration points 112. That is, since all the apertures 98 are threaded, a pin 112 may be threaded into the aperture 98 on each of several pillars 96. Typically, three to four pins 112 extending from appropriate places, typically threaded apertures 98 of the lattice 90 may extend out each face (side) in order to assure precise placement of the outer skins 46. Again, the outer skins 46 may typically be aluminum, composite materials, or any particular material that serves as a mechanical outermost fiber, or layer, for the apparatus 10 as a structure. In some embodiments, aluminum may be preferred as an outer skin 46 as it tends to provide excellent thermal conductivity and emissivity and radiation shielding for satellite components. Nevertheless, other materials (i.e., dielectric materials) may also serve as outer coatings or the entire outer skin 46 itself on either or both sides.
Thus, for rapid assembly, the lattice 90 provides for registration of outer skins 46 with several matching holes selected from the layout of mounting holes 28 all aligned precisely in accordance with the threaded apertures 98 in the pillars 96 of the lattice 90.
Referring to
Referring to
Meanwhile, as illustrated in
Meanwhile, registration is provided in all dimensions, with the lattice for the panels and bond frames for the panel-to-panel connections. For example, the relief 104 provided for each heat pipe 40 aligns, registers, and protects each of the heat pipe strips 40. Meanwhile, the outer skin 46 protects all the honeycomb inserts 100 and the heat pipe strips 40 covered by them. Meanwhile, the bonding layers 106 and bonding strips 108 provide intimate thermal contact and mechanical stability throughout.
The present invention may be embodied in other specific forms without departing from its fundamental functions or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. All changes which come within the meaning and range of equivalency of the illustrative embodiments are to be embraced within their scope.
What is claimed and desired to be secured by United States Letters Patent is:
This application claims priority to U.S. Provisional Patent Application Serial No. 63/439,979 filed on Jan. 19, 2023, which is hereby incorporated herein by reference in its entirety. This application hereby incorporates herein by reference U.S. Pat. No. 9,149,896, issued Oct. 6, 2015 to Batty et al. and titled THERMAL-CONTROL, TRUSS-PLATE APPARATUS AND METHOD.
| Number | Date | Country | |
|---|---|---|---|
| 63439979 | Jan 2023 | US |
