Radiator system and cooling system for a satellite, as well as satellite

Abstract

A radiator system for a satellite is described. The radiator system comprises a planar radiator panel with an upper and a lower support layer, as well as a heat-conducting layer that extends at least partially between the upper and lower support layers. The at least one radiator panel includes at least one connecting element that is arranged between the upper and lower support layers and is connected to both, such that the upper and lower support layers are fastened to each other at least via this at least one connecting element. A cooling system and a satellite are also described.

Description

Satellites generally comprise electrical loads, such as processors, cameras, measuring devices, etc. Electrical loads convert a greater or lesser amount of electrical energy into heat during operation. While this heat can usually be dissipated without problems to the surrounding gas atmosphere in the case of electrical consumers on the earth, this is not possible in the case of satellites, since these are in vacuum during operation. Instead, satellites must radiate heat to the environment in order to maintain their operating temperature. Various active and passive cooling systems have been developed over time for this purpose.Up to now, more complex cooling systems have been used on comparatively large satellites with volumes of up to several cubic meters or also on manned space stations. Such cooling systems may include mechanically deployable surfaces to increase the radiating surface area and thus increase the maximum possible radiation of heat from the satellite. However, the technology required for this is generally complex, heavy and not easy to miniaturize.In recent years, small and very small satellites such as, for example, so-called cubeAts with sizes in the range of a few cubic decimeters are increasingly being used. The outer dimension of CubeAts is also given in the unit U, where 1U=10 cm x10 cm x10 cm. Initially, these compact satellites were only provided with basic functions that could be provided by low power electrical loads. Cooling using a dedicated cooling system was therefore not necessary.Recently, however, small and very small satellites are also equipped with comparatively powerful electrical loads in order to expand their functions. Thus, for example, a 12U CubeAt can be designed to consume up to 100 W during operation. In such cases, it may be helpful or necessary to provide the satellite with a radiator and / or cooling system. However, since the traditional cooling systems are comparatively large, they cannot be used simply for small and small satellites.US 2019 / 0 315 501 A1 discloses a device having a structure configured to absorb thermal energy and to release this thermal energy to an external environment. The structure includes a lid and a body. The structure also includes (i) a plurality of thermomechanical regions connected in series and interconnected, and (ii) one or more oscillating heat pipes embedded in at least some of the thermomechanical regions. Different portions of at least one of the cover and body elements form the thermomechanical regions. The one or more oscillating heat pipes are configured to transfer the thermal energy between different ones of the thermomechanical regions. At least one of the thermomechanical regions comprises one or more shape memory materials configured to effect a change in the shape of the structure. Each of the one or more oscillating heat pipes includes at least one channel in the structure.US 2019 / 0 329 912 A1 describes a first deployment mechanism that deploys a first radiator plate from a state where the first radiator plate is located opposite a north or south side of the body structure of a satellite. A second radiating plate is stacked with the first radiating plate so as to be opposed to the north or south side of the body structure of the satellite. A second deployment mechanism connects the second radiator plate to the north or south side of the body structure of the satellite and deploys the second radiator panel in a direction opposite the deployment direction of the first radiator panel.From CN 1 17 644 996 A an optical satellite is known, which comprises a satellite body, an infrared thermal imaging load and a multi-spectral band load for weak light conditions, wherein the infrared thermal imaging load is arranged on one side of the satellite body in the positive x-direction and is provided with a first heat dissipation surface, and wherein the first heat dissipation surface in the assembled state is located on one side of the optical satellite in the positive y-direction. The low-light multi-spectral band load is disposed on a side of the infrared thermal imaging load along the positive direction of the x direction and provided with a second heat dissipation surface, the second heat dissipation surface being located on a side of the optical satellite in the positive y direction in the mounted state.US 4 832 113 A discloses a heat radiating system for use in a spacecraft which can survive a long time without use and then radiate large amounts of heat for a limited period of time. The radiator includes groups of radiator plates pivotally connected in series so that they can be placed in an extended configuration in which the plates are substantially coplanar and a stowed configuration in which the plates are stacked to resist damage from micrometéories. The panels are mounted on a cantilever beam which separates a hot energy source from a payload. Coolant flows through internal channels of the panels.Against this background, it can be regarded as an object of the present invention to provide a solution which, in particular, enables small and very small satellites having high power densities to emit sufficient heat so that their operating temperature can be maintained. An object can also be seen in providing a particularly compact and light radiator and / or cooling system for a satellite. It may also be seen an object to provide an effective passive radiator system for a satellite.According to a first aspect of the invention, there is provided a radiator system for a satellite.The radiator system comprises at least one planar radiator panel having an upper carrier layer and a lower carrier layer arranged substantially parallel to the upper carrier layer, wherein the radiator system further comprises a heat-conducting layer which extends at least in sections between the upper carrier layer and the lower carrier layer of the at least one radiator panel, and wherein the at least one radiator panel comprises at least one connecting element which is arranged between the upper carrier layer and the lower carrier layer and are connected both to the upper carrier layer and to the lower carrier layer, such that the upper carrier layer and the lower carrier layer are fastened to one another at least via the at least one connecting element.The at least one radiator panel may be substantially planar. For example, the at least one radiator panel has a substantially rectangular outline (e.g. in plan view). The at least one radiator panel is in particular of rigid design, that is to say in such a way that it retains a predetermined, substantially planar shape at least under space conditions, but preferably also on the earth and under gravity, and / or that it has a flexural rigidity of at least 10 kN / mm 2 for example a flexural rigidity of ≥20, ≥25, ≥50, ≥100, ≥200 or ≥300 kN / mm 2. The radiator panel can be designed as a self-supporting component.The upper carrier layer may have the same outline (e.g. in plan view) as the lower carrier layer. The upper and the lower carrier layer can lie congruently one above the other (e.g. in plan view). The upper carrier layer is spaced apart from the lower carrier layer in one example only by the heat conducting layer. The upper support layer may be substantially planar. For example, the upper carrier layer has a substantially rectangular contour (e.g. in plan view). The upper carrier layer is in particular of rigid design. The lower support layer may be substantially planar. For example, the lower carrier layer has a substantially rectangular contour (e.g. in plan view). The lower carrier layer is in particular of rigid design. The upper carrier layer can be free of projections and / or smooth at least on its side facing the heat-conducting layer. The lower carrier layer can be free of projections and / or smooth at least on its side facing the heat-conducting layer. The upper carrier layer and / or the lower carrier layer can comprise or consist of a fiber-reinforced, in particular fabric-reinforced plastic (e.g. polymer). The same applies to the lower carrier layer.In one example, the heat-conducting layer comprises or consists at least partially of a material which is not part of the upper and / or the lower carrier layer. The heat-conducting layer on the one hand, and the upper carrier layer and / or the lower carrier layer on the other hand, can be manufactured from different materials.The heat-conducting layer extends, in particular, at least in sections into the at least one radiator panel. The heat conducting layer may form a core and / or an innermost layer of the at least one radiator panel. The heat-conducting layer extends, for example, at least in sections next to the at least one radiator panel, in particular next to an intermediate space which lies between the upper carrier layer and the lower carrier layer. The heat-conducting layer may have an outline which encloses the outline of the upper carrier layer and / or the outline of the lower carrier layer (e.g. in plan view). The heat-conducting layer can be flexible or flexible, i.e. have a flexural rigidity of less than 10 kN / mm 2 for example, in particular a flexural rigidity of ≤5,000, ≤2.500, ≤1.000, ≤900, ≤750), ≤500, ≤250, ≤100 or ≤50 N / mm 2.The at least one connecting element is arranged in particular completely between the upper carrier layer and the lower carrier layer. The at least one connecting element can be connected to the upper and / or the lower carrier layer in a materially continuous manner. The at least one connecting element can be manufactured in one piece, in particular in one piece with the upper carrier layer and / or the lower carrier layer. The at least one connecting element can be rigid.The at least one radiator panel may comprise a plurality of the connection elements. In this case, the connecting elements of the at least one radiator panel can be arranged at regular intervals, for example in a square or triangular grid (for example in plan view).The radiator system is designed in particular for the equipment of a small or smallest satellite. The at least one radiator panel may have a maximum thickness of one or a few millimeters, or even less than one millimeter. The outline of the radiator panel (e.g. in plan view) may be equal to or less than 10×10 cm.In an exemplary embodiment, the at least one connecting element is pillar-shaped and / or cylindrical (e.g. circular cylindrical). The at least one connecting element extends, for example, perpendicularly with respect to the upper carrier layer and / or the lower carrier layer.It can be provided that the at least one connecting element extends through the heat-conducting layer of the radiator system. The heat conducting layer may comprise a through hole through which the connecting element extends. The heat-conducting layer can comprise a separate through-hole for each connecting element, through which the respective connecting element extends.For example, the at least one connecting element is designed such that it (for example at least under space conditions, in particular under vacuum in zero gravity) {i} brings about a compression pressure on a section of the heat-conducting layer which lies between the upper carrier layer and the lower carrier layer of the at least one radiator panel or / and {ii} pushes the upper carrier layer and the lower carrier layer towards one another. The at least one connecting element may cause a compression of a portion of the heat conducting layer that lies between the upper carrier layer and the lower carrier layer of the at least one radiator panel, for example by applying a tensile force to the upper carrier layer and the lower carrier layer, which urges the upper carrier layer and the lower carrier layer towards each other. The at least one connecting element can bias the upper carrier layer in the direction of the lower carrier layer and vice versa. The at least one connecting element can be under tensile stress, in particular in its longitudinal direction (e.g. which runs, for example, normally to the upper carrier layer and / or the lower carrier layer). The at least one connecting element is in particular of rigid design.In one example, the at least one connecting element consists at least partially of a first (e.g. rigid) polymer. In particular, the first polymer can be produced by polymerization of a (e.g. gel-like or viscous) monomer or / and oligomer mixture. The polymerization can take place, for example, after the upper carrier layer has been applied to the heat-conducting layer and the heat-conducting layer has been applied to the lower carrier layer, or / and while the upper carrier layer and the lower carrier layer are pressed towards one another (for example with the section of the heat-conducting layer lying therebetween). It can then be said that the at least one connecting element consists at least partially of a first polymer which has been polymerized and / or cured "in situ". The first polymer can be an epoxy resin, wherein other types of polymers such as polyester, polyurethane or the like are also conceivable.The upper carrier layer may be made of the same material as the lower carrier layer. However, it is also conceivable to use a different material for the upper carrier layer than for the lower carrier layer.For example, the upper carrier layer of the at least one radiator panel comprises a fabric. This fabric may be penetrated by a polymer. This polymer can be produced by polymerization of a (e.g. gel-like or viscous) monomer and / or oligomer mixture. The polymerization can only take place, for example, when the upper carrier layer has been applied to the heat-conducting layer. It can then be said that the fabric of the upper carrier layer is penetrated by a polymer which has been polymerized and / or cured "in situ". In particular, the fabric of the upper carrier layer can be penetrated by the first polymer. The fabric may comprise or be a glass fibre or carbon fibre fabric.Alternatively or additionally, the lower carrier layer of the at least one radiator panel can comprise a fabric. This fabric may be penetrated by a polymer. This polymer can be produced by polymerization of a (e.g. gel-like or viscous) monomer and / or oligomer mixture. The polymerization can take place, for example, only when the heat-conducting layer has been applied to the lower carrier layer. It can then be said that the fabric of the lower carrier layer is penetrated by a polymer which has been polymerized and / or cured "in situ". In particular, the fabric of the lower carrier layer can be penetrated by the first polymer. The fabric may comprise or be a glass fibre or carbon fibre fabric.The heat conducting layer can comprise or consist of graphite material, for example layer-shaped or block-shaped graphite material. The heat-conducting layer comprises or consists in particular of one or more graphite layers. The heat-conducting layer can comprise or consist of a multiplicity of graphite layers which are stacked one above the other. Each graphite layer may be a pyrolytic graphite film (PGS), also referred to as a pyrolytic graphite sheet (PGS). The heat conducting layer may comprise or consist of an unannealed stack of graphite layers. Thus, for the production of the heat conducting layer, for example, a plurality of graphite layers can be placed one above the other without these being chemically bonded to one another by a subsequent high-temperature treatment.For example, the radiator system comprises an upper flexible cover layer which extends at least in sections between the upper carrier layer and the heat-conducting layer of the at least one radiator panel. The upper flexible covering layer is accordingly not rigid but rather flexible, in particular elastically reversibly bendable. The upper flexible cover layer is in particular impermeable to dust. The upper flexible covering layer can be glued to the heat conducting layer (e.g. covering the surface or at points) or can rest on the heat conducting layer. It is conceivable that the upper flexible covering layer substantially completely covers an upper side of the heat-conducting layer. The upper flexible cover layer may be made at least partially of plastic, for example polyimide, polyester, polyethylene naphthalate, polytetrafluoroethylene or polyamide (e.g., aramid). The upper flexible cover layer can be formed as a plastic film and / or adhesive film. It is thus conceivable to use a Kapton® film as the upper flexible cover layer. It is also conceivable that the upper flexible cover layer forms at least a part of a substrate of a flexible printed circuit board.Alternatively or additionally, the radiator system can comprise a lower flexible cover layer, which extends at least in sections between the lower carrier layer and the heat-conducting layer of the at least one radiator panel. The lower flexible cover layer is accordingly not rigid but flexible, in particular elastically reversibly bendable. The lower flexible cover layer is in particular impermeable to dust. The lower flexible covering layer can be glued to the heat conducting layer (e.g. covering the surface or at points) or the heat conducting layer can rest on the lower covering layer. It is conceivable that the lower flexible cover layer substantially completely covers an underside of the heat-conducting layer. The lower flexible cover layer can consist at least partially of plastic, for example of polyimide, polyester, polyethylene naphthalate, polytetrafluoroethylene or polyamide (e.g. aramid). The lower flexible cover layer can be formed as a plastic film and / or adhesive film. It is thus conceivable to use a Kapton® film as the lower flexible cover layer. It is also conceivable that the lower flexible cover layer forms at least a part of a substrate of a flexible printed circuit board.For example, the at least one connecting element extends through the upper flexible cover layer. The upper flexible cover layer may include a separate through hole for each connector, through which the respective connector extends.Alternatively or additionally, the at least one connecting element may extend through the lower flexible cover layer. The lower flexible cover layer may include a separate through hole for each connector, through which the respective connector extends.The expression "at least one" radiator panel can stand for exactly one radiator panel, but also for two, three or more radiator panels. The radiator system may comprise two or more of the planar radiator panels. In this case, the radiator system can be designed such that the radiator panels in a transport state {i} lie one above the other in a stack-like manner and / or {ii} lie in different, in particular substantially parallel, planes and / or {iii} are arranged such that the upper carrier layers (for example adjacent) radiator panels are aligned in substantially opposite directions (for example with a deviation of less than 10°). The radiator system may be configured such that in a working state {i} the radiator panels are not stacked one above the other or / and {ii} are arranged substantially in a plane (e.g. aligned) or / and {iii} are arranged such that the upper carrier layers of the radiator panels are aligned substantially in the same direction (e.g. with a deviation of less than 10°). In this case, the radiator system is then in particular designed such that the radiator panels fold out when the radiator system is moved from the transport state into the working state. The radiator system can also be referred to as a fold-out multi-radiator panel arrangement.In an exemplary embodiment, adjacent radiator panels of the radiator system are each connected to one another in a foldable manner via at least one flexible connecting section. The flexible connecting portion can be configured hinge-free. The adjacent radiator panels can be unfolded when being shifted from the transport state into the working state, wherein the at least one flexible connecting section connects the radiator panels to one another both in the transport state and in the working state. When the radiator panels are hinged open, the at least one flexible connecting section must bend in particular. Therefore, it is not rigid, but is flexible.The heat conducting layer may be designed and arranged to allow heat transport from a radiator panel through the at least one connecting portion to an adjacent radiator panel. For example, the heat-conducting layer extends through the at least one connecting section. The heat conducting layer may extend from a radiator panel to a radiator panel adjacent thereto through the at least one connecting portion. The heat-conducting layer can be formed as a continuous layer which extends in sections between the upper carrier layer and the lower carrier layer of different radiator panels, and also by the at least one connecting section which connects these radiator panels to one another. It can be said that the radiator panels can be connected at least partially via the heat conducting layer.The at least one connecting portion may be configured to provide a first bias urging the radiator panels connected via the at least one connecting portion into their operative state. At least a part of the first prestress can be provided by the heat-conducting layer and / or the upper covering layer and / or the lower covering layer. For example, at least in the region of the at least one connecting section, the heat-conducting layer and / or the upper cover layer and / or the lower cover layer are under a bending stress opposite the first prestress. The at least one connecting section can be designed as a ribbon spring.The radiator system may comprise an adjustment unit which is designed such that it fixes the relative positions of two adjacent radiator panels of the radiator system at least in their working state. The adjustment unit may comprise a hinge having two hinge wings, each of which is attached to a different one of the two adjacent radiator panels. The hinge can be designed such that it latches into its working state after the adjacent radiator panels have been moved or folded out, so that it fixes the position of these radiator panels in their working state (for example irreversibly or reversibly only by use of tools). The hinge may be configured to provide a second bias urging the radiator panels connected via the hinge into their operative state. For this purpose, the hinge can comprise a spring, in particular be designed as a spring hinge. The adjustment unit and / or the hinge can be designed as a thermal insulator and / or consist of a material which differs from the material of the heat-conducting layer. In particular, the hinge is free of the heat-conducting layer.It is conceivable that the upper flexible cover layer extends through the at least one connecting portion. The upper flexible cover layer may extend from a radiator panel to a radiator panel adjacent thereto through the at least one connection portion. The upper flexible cover layer may be formed as a continuous layer extending in sections between the upper support layer and a section of the heat conducting layer of different radiator panels, and also through the at least one connecting section connecting these radiator panels to each other. It can be said that the radiator panels can be at least partially connected via the upper flexible cover layer.Alternatively or additionally, the lower flexible cover layer may extend through the at least one connecting portion. The lower flexible cover layer may extend from a radiator panel to a radiator panel adjacent thereto through the at least one connection portion. The lower flexible cover layer can be formed as a continuous layer, which extends in sections between the lower carrier layer and a section of the heat-conducting layer of different radiator panels, and also by the at least one connecting section, which connects these radiator panels to one another. It can be said that the radiator panels can be at least partially connected via the lower flexible cover layer.In a first variant, the at least one connecting section can be formed (e.g. exclusively) by the heat-conducting layer and {i} the upper flexible cover layer and / or {ii} the lower flexible cover layer. It is conceivable that in the region of the at least one connecting section the upper flexible cover layer is the uppermost layer of the radiator system or / and the lower flexible cover layer is the lowermost layer of the radiator system. The radiator system may be configured such that the upper cover layer forms an outer (e.g. uncovered) surface of the radiator system at least in the region of the at least one connection section. The radiator system may be configured such that the lower cover layer forms an outer (e.g. uncovered) surface of the radiator system at least in the region of the at least one connection section. The at least one connecting section can be exposed, i.e. in particular configured without additional (fabric) connecting sections.In a second variant, the radiator system can comprise: {i} an upper fabric layer which extends at least in sections through the at least one connecting section, and / or {ii} a lower fabric layer which extends at least in sections through the at least one connecting section. In the second variant, the at least one connecting portion can be formed (e.g. exclusively) by the heat-conducting layer and {i} a portion of the upper fabric layer and / or {ii} a portion of the lower fabric layer, optionally also by {a} the upper flexible cover layer and / or {b} the lower flexible cover layer. For example, the (e.g. continuous) upper fabric layer forms the fabric of the upper carrier layers of the two or more radiator panels of the radiator system. For example, the (e.g. continuous) lower fabric layer forms the fabric of the lower carrier layers of the two or more radiator panels of the radiator system. At least a part of the first prestress can be provided by the upper fabric layer and / or the lower fabric layer.The upper fabric layer can be penetrated by a second polymer, which is different from the first polymer, at least in the region of the at least one connecting section. For example, the lower fabric layer is penetrated by the second polymer, which is different from the first polymer, or by a third polymer, which is different from the first and from the second polymer, at least in the region of the at least one connecting section. The second polymer and / or the third polymer is in particular flexible, i.e. not rigid. The second polymer can be, for example, a silicone polymer, wherein other, in particular rubber-like, polymer types are also conceivable. At least a part of the first prestress can be provided by the second polymer or the polymer-permeated upper fabric layer and / or the polymer-permeated lower fabric layer. The upper fabric layer may be a fiberglass or carbon fiber fabric layer. The same applies to the lower fabric layer.The second polymer can be produced by polymerization of a (e.g. gel-like or viscous) monomer or / and oligomer mixture which has been applied in particular in a location-selective manner (e.g. exclusively in the region of the at least one connecting section) to the upper fabric layer or / and the lower fabric layer. The polymerization can take place, for example, before the fabric of the upper carrier layer is applied to the heat-conducting layer (e.g. with an upper covering layer located therebetween) or / and before the heat-conducting layer is applied to the fabric of the lower carrier layer (e.g. with a lower covering layer located therebetween). Alternatively, it is conceivable that the polymerization for forming the second polymer only takes place when the fabric of the upper carrier layer has been applied to the heat-conducting layer (e.g. with an intermediate upper cover layer) or / and when the heat-conducting layer has been applied to the fabric of the lower carrier layer (e.g. with an intermediate lower cover layer). It can be said in the latter case that the second polymer has been polymerized "in situ". The first polymer may be polymerized after the second polymer, or vice versa.In a special modification of the second variant, the upper fabric layer is separate from the fabric of one or more of the upper carrier layers and / or the lower fabric layer is separate from the fabric of one or more of the lower carrier layers. In this case, the upper fabric layer can be penetrated by the first polymer at least in a respective connection region to the separate fabric of the upper carrier layer(s), such that the position of the upper fabric layer is fixed with respect to the upper carrier layers. The lower fabric layer can be penetrated by the first polymer at least in a respective connection region to the separate fabric of the lower carrier layer(s), so that the position of the lower fabric layer is fixed with respect to the lower carrier layers.It is conceivable that the upper cover layer, the lower cover layer, the upper fabric layer in the region of the at least one connecting section and / or the lower fabric layer in the region of the at least one connecting section comprises a (e.g. thermo-optical) coating which is designed in particular such that it determines thermal radiation properties. This coating may be either a paint, paint or adhesive film applied to an underlying surface. The coating is applied on the outside, for example, it being possible to say that it is arranged facing the world.The radiator system may comprise at least one attachment portion configured for attachment to a module panel or / and a satellite. A respective portion of the heat conducting layer may extend through the at least one fastening portion. A respective portion of the upper cover layer and / or a respective portion of the lower cover layer may extend through the at least one attachment portion. A respective portion of the upper fabric layer and / or a respective portion of the lower fabric layer may extend through the at least one attachment portion. The at least one fastening portion can be configured in the same way as the at least one radiator panel, but preferably does not have a connecting element. The at least one fastening section is connected in particular via at least one flexible connecting section to an adjacent radiator panel of the radiator system. This at least one flexible connecting portion can be designed as the above-described at least one connecting portion connecting two adjacent radiator panels.It is conceivable, although not necessarily advantageous, that not every radiator panel of the radiator system comprises the at least one connecting element. In a particular variant not presently claimed but to be regarded as part of the present disclosure, the at least one radiator panel does not comprise the radiator system the at least one connecting element.According to a second aspect of the invention, there is provided a cooling system for a satellite.The cooling system includes a module plate configured for attachment to a satellite. The module plate can be manufactured in one piece. The module plate can be manufactured from metal or a metal alloy, for example from aluminum or from an aluminum alloy. The module plate can comprise at least one recess (e.g. one facing the satellite) for a respective heat pipe, which is in particular designed as a so-called heat pipe or two-phase thermosiphon. The heat pipe can be part of the cooling system or part of the satellite. The module plate may further comprise through holes for fastening means serving for fastening the module plate to the satellite.The cooling system comprises at least one radiator system according to the first aspect, but in particular at least two radiator systems according to the first aspect. The radiator system(s) is or are each fixed to the module plate. In particular, each radiator system is fixed to the module plate by the at least one fixing portion. Each fastening section can be pressed onto the module plate by a respective fastening unit of the cooling system. For example, the fastening sections rest on the module plate in a region under which the at least one recess of the module plate is arranged.In an exemplary embodiment, the radiator panels of the at least two radiator systems of the cooling system form a single stack in their respective transport state. In particular, all radiator panels of all radiator systems of the cooling panel can form a single stack in the transport state. For example, the radiator panels of different radiator systems of the cooling system lie in different planes in the operating state. It is thus conceivable that the radiator panels of a first radiator system of the cooling system in the working state lie in a plane which is tilted by 45° with respect to its position in the transport state, while the radiator panels of a second radiator system of the cooling system in the working state lie in a plane which is tilted by 135° with respect to its position in the transport state.The cooling system may further comprise an actuator unit configured to, in a blocking state, block movement (e.g. rotation or unfolding) of the radiator panels of the cooling system from their transport state to their working state, and, in a release state, allow movement of the radiator panels of the cooling system from their transport state to their working state. The actuator unit can be designed such that it can be brought from the blocking state into the release state by electrical actuation. The actuator unit can be designed as a so-called "release groove". The actuator unit can be, for example, the actuator module described in the patent application DE 10 2020 000 688 of 31 January 2020 or the actuator module described in the patent application DE 10 2022 129 934 of 11 November 2022, wherein other types of release groove or pin pullers can also be used.According to a third aspect of the invention, a satellite is provided.The satellite is, for example, a small satellite or a smallest satellite, in particular a so-called CubeAt. The satellite may have a size of a few U, for example 1U, 2U, 6U, 12U, 16U or 24U. The satellite can have a mass of less than 40 kg, in particular less than 20 kg or less than 10 kg.The satellite comprises at least one radiator system according to the first aspect and / or at least one cooling system according to the second aspect. The satellite may include a thermal interface configured to couple to the module plate and / or the at least one heat pipe. The module plate can be fastened to the satellite in such a way that heat can be transferred via the heat interface into the module plate, where it can then flow through the fastening sections into the individual radiator systems and be radiated from there into the world.The satellite comprises in particular a control unit which is electrically connected to the actuator unit of the cooling system and is designed such that it can electrically actuate the actuator unit in order to bring it from the blocking state into the release state. The control unit can accordingly bring about, at the desired point in time, for example after a stable orbit has been reached, by appropriate control of the actuator unit, a folding open of the radiator panels from their transport state into their working state.The invention is explained in more detail below with reference to the attached drawings. They represent: FIG. 1 illustrates a first example radiator system; FIG. 2 illustrates a second example radiator system; FIG. 3 is an exploded view of an exemplary cooling system; FIG. 4 shows a perspective view of the cooling system from FIG. 3 in its transport state; FIG. 5 shows a view of the underside of the cooling system from FIG. 3 in its transport state; FIG. 6 is a sectional view taken along line A-A of FIG. 5 in the transport state of the cooling system; FIG. 7 is a sectional view taken along line B-B of FIG. 5 in the transport state of the cooling system; FIG. 8 is a perspective view of the cooling system from FIG. 3 in its operating state; FIG. 9 is a sectional view taken along line A-A in the operating state of the cooling system; and FIG. 10 is a sectional view taken along line B-B in the operating state of the cooling system.In the following, unless otherwise explained, the same reference numerals designate the same structural and functional features. If a feature X is present multiple times, it can be numbered X-1, X-2, etc.Referring to FIG. 1, a first example radiator system 100 is shown. The radiator system 100 is designed for the equipment of a satellite (e.g. CubeAt), that is to say is correspondingly compact and light-weight. The radiator system 100 comprises two planar radiator panels 2- 1, 2- 2 which each have an upper carrier layer 4- 1, 4- 2 and a lower carrier layer 6- 1, 6- 2.The two radiator panels 2- 1, 2- 2 each of which is rigidly formed are connected to one another via a flexible connecting section 8, such that the radiator panels 2- 1, 2- 2 can be opened from a transport state, in which they are stacked one above the other, into a working state, in which they are situated in the same plane. Referring to FIG. 1, the radiator system 100 is shown during deployment.The radiator system 100 comprises an upper fabric layer 10 of carbon fiber fabric and a lower fabric layer 12 of carbon fiber fabric. These two fabric layers 10, 12 extend continuously through the two radiator panels 2- 1, 2- 2 and also the connecting section 8. The respective upper carrier layer 4- 1, 4- 2 comprises a fabric which is part of the upper fabric layer 10. The respective lower carrier layer 6- 1, 6- 2 comprises a fabric which is part of the lower fabric layer 12. The fabric of the upper carrier layer 4- 1, 4- 2 and the fabric of the lower carrier layer 6- 1, 6- 2 are each penetrated by a first polymer such as epoxy resin, which ensures that the respective fabric forms a rigid plate. In the region of the connecting section 8, on the other hand, the upper fabric layer 10 and the lower fabric layer 12 are not penetrated by the first polymer, but by a second, more flexible polymer such as silicone. The upper and lower fabric layers 10, 12 thus each have a flexible section 14, 16 in the region of the connecting section 8. It can be said that the respective radiator panels 2- 1, 2- 2 are rigid, whereas the connecting portion 8 is reversibly elastically deformable, in particular bendable by 180°.The radiator system 100 also comprises a heat conducting layer 18 which extends continuously through the two radiator panels 2- 1, 2- 2 and also through the connecting section 8. The heat conducting layer 18 is formed from a stack of pyrolytic graphite films 20-1 to 20-4 of equal dimensions. The flexible portions 14, 16 wrap the graphite films 20-1 to 20-4 in the joint portion 8, and serve particularly to retain fragments and dust of the graphite films 20-1 to 20-4 inside the radiator system.Such a heat conducting layer 18 has high thermal conductivity particularly when the individual graphite films 20- 1 to 20- 4 are in pressure contact with each other. Therefore, connecting members 22-1 to 22-3 are provided which extend through through-holes 23-1 to 23-3 in the graphite films 20-1 to 20-4 from the respective upper support layer 4-1, 4-2 to the respective lower support layer 6-1, 6-2. These connecting elements 22 serve to fasten the upper carrier layer 4 and the lower carrier layer 6 to one another. In this case, the connecting elements 22 are each under tensile stress. In other words, the radiator system 100 is designed such that the connecting elements 22 exert a compression pressure on the heat-conducting layer 18 by means of the upper carrier layer 4 and the lower carrier layer 6. The connecting elements 22 are preferably made of the first polymer.In particular, the upper fabric layer 10, the lower fabric layer 12 and the through-holes 23 in the graphite films 20- 1 to 20- 4 may be filled with a monomer and / or oligomer mixture, then a compression pressure (e.g. 1000 hPa) may be applied from the outside to the superimposed layers 10, 18, 12 and then the monomer and / or oligomer mixture may be polymerized. After polymerization, the external compression pressure can be removed. Thus, the connecting elements 22, which are manufactured "in situ", remain under tensile stress and the graphite films 20 are still compressed, even without exposure to external pressure.FIG. 2 shows a second example radiator system 200. To avoid repetitions, the differences from the radiator system 100 will be discussed predominantly.The radiator system 200 comprises an upper cover layer 24 which is arranged on the upper side of the heat conducting layer 18 and extends both between the heat conducting layer 18 and the upper carrier layers 4- 1, 4- 2 and through the flexible connecting portion 8, Furthermore, the radiator system 200 comprises, on the other side of the heat conducting layer 18, a lower cover layer 26 which also extends through the flexible connecting portion 8 and is arranged in the radiator panels 2- 1, 2- 2 between the respective lower carrier layers 6- 1, 6- 2 and the heat conducting layer 18. In the region of the flexible connecting portion, the two cover layers 24, 26 form the outermost and outer layers of the radiator system 200, respectively. At least in this area, the cover layers 24, 26 serve to retain debris and dust of the pyrolytic graphite layers 20 within the radiator system 200.In the example shown, in contrast to the radiator system 100, no continuous upper fabric layer 10 and also no continuous lower fabric layer 12 are provided. Instead, the upper carrier layers 4- 1, 4- 2 and also the lower carrier layers 6- 1, 6- 2 are each formed by separate fabric layer sections, which are each penetrated by the first polymer. As in the radiator system 100, connecting elements 22 manufactured "in situ" are also provided here, so that a compression of the stack of graphite layers 20 is ensured at least in the region of the radiator panels 2- 1, 2- 2.It is understood that the radiator system 100, 200 may comprise more than only the two radiator panels 2- 1, 2- 2 shown. Three or more panels 2 can be provided, of which adjacent panels are each connected via a connecting section 8. In addition, the number of connecting elements 22, the number of graphite layers 20 and / or the dimensioning of the individual components can deviate from FIGS. 1 and 2. Further modifications are conceivable, as explained above with reference to the first aspect, for example.An exploded view of an exemplary cooling system 300 for a satellite 47 is shown in FIG. 3. The cooling system 300 comprises two radiator systems 100 and 200, respectively. The radiator panels 2 are shown in FIG. 3 in their working state, in which they enable a radiation of heat into the world.In the example shown, the radiator systems 100, 200 each have a plurality of fastening sections 28, which can be formed in the same way as the radiator panels 2- 1, 2- 2, but without a connecting element 22 or / and without carrier layer(s) 4, 6. The connecting portions 41 can be formed in the same way as the connecting portions 8, and each fastening portion 28 is covered by a fastening plate 29. The fastening plate 29 is fastened to a module plate 38 by fastening means 37 and in the process clamps the fastening section 28. The resulting contact pressure of the fastening section 28 on the module plate 38 enables effective heat transport from the module plate 38 into the respective radiator system 100, 200.The module plate 38 is milled in particular from one piece of aluminum and has, on its side 40 facing away from the radiator systems 100, 200 and thus facing the satellite 47, a plurality of elongate recesses 42, in which heat pipes 44 are arranged. The heat pipes 44 are arranged in such a way that they extend beyond the fastening sections 28 in plan view. Thus, uniform heat distribution over all the fixing portions 28 can be ensured. The module plate 38 is designed for attachment to the satellite 47. Heat to be dissipated from the satellite 47 can be transferred through the module plate 38 and via the fastening sections 28 into the respective radiator system 100, 200 and from there be radiated into the space.In the example shown, each radiator system 100, 200 also has a plurality of hinges 30- 1, 30- 2, which respectively connect two adjacent radiator panels 2- 1, 2- 2. One or more of these hinges 30-1, 30-2 is provided with a spring 39 which biases the adjacent radiator panels 2-1, 2-2 in the direction of their working state. In addition, the hinges 30 each have a latching mechanism, so that the radiator panels 2- 1, 2- 2 remain in this position after the movement into their working state, i.e. lie in particular in the same plane. In the example shown, the hinges 30 each extend in a free space 31- 1, 31- 2 between the adjacent radiator panels 2- 1, 2- 2. Further free spaces 33- 1, 33- 2 are also provided between the adjacent radiator panels 2- 1, 2- 2. Through these free spaces 33, fastening means 35 (e.g. screws) can be introduced in the direction of the satellite 47 when the radiator panels 2 are in their transport state. Washers 49 and / or 51 made of a thermally insulating material, for example, of polyetheretherketone (PEEK), can be provided for fastening means 35.In addition, a through hole 32 is provided in a panel 2- 2 which faces the satellite 47 in the transport state. A holding element 34 is fastened to a radiator panel 2- 1 of a first of the radiator systems 100, 200, which radiator panel is situated away from the satellite 47 in the transport state and in particular forms an uppermost stack layer of the stack of radiator panels 2 in the transport state. This holding element 34 can extend through the through-holes 32 of all further radiator panels 2 in the transport state of all radiator panels 2 and is designed in particular for coupling to an actuator unit 36 of the cooling system 300, which is preferably designed as a so-called "release groove". The holding element can be the "groove" or nut to be released.The actuator unit 36 can be fixed to the module plate 40, and is arranged in particular on a side 40 of the module plate 38 facing the satellite. The actuator unit 36 is designed such that, in a blocking state, it prevents a movement of the retaining element 34 away from the module plate 38 and permits such a movement of the retaining element 34 in a release state. The actuator unit 36 can be shifted from the blocking state into the release state by corresponding electrical actuation via an electrical interface 46.After releasing the holding element 34, the radiator panels 2 move from their transport state into their working state. Here, no motor is required for driving the radiator panels 2. The radiator panels 2 may be biased towards their working state, in particular by the elastic energy stored in the springs 39 and in the connecting portions 8. It can thus be said that the radiator panels 2 automatically fold out from the transport state into the working state after the activation of the actuator unit 36.FIG. 4 shows a perspective view of the cooling system 300 in its transport state, and FIG. 5 shows a view of the underside 40 of the cooling system 300 in the transport state.It can be seen that the radiator panels 2 of the two radiator systems 100, 200 form a single stack in the transport state. It is thus ensured that the cooling system 300 occupies a small installation space at least in the transport state of the radiator panels 2.It can also be seen that the fastening means 35 can be passed through the free spaces 33 in this state in order to fasten the module plate 38 to the satellite 47. This enables a particularly simple mounting of the cooling system 300 on the satellite 47.It can also be seen that the radiator systems 100, 200 are not only fastened to the module plate 38 via their fastening section 28, but that for this purpose further hinges 42 are provided, which are again equipped with corresponding springs 39, for example, and which are fixed on the one hand to the module plate 38 and on the other hand to a radiator panel 2 of the respective radiator system 100, 200. The hinges 30, 42 may be glued to a surface of the upper support layer 4 or / and a surface of the lower support layer 6 of the respective radiator panel 2 for attachment to the respective radiator panels 2.FIG. 6 is a sectional view taken along line A-A, and FIG. 7 is a sectional view taken along line B-B of FIG. 5.As can be seen, the radiator panels 2 are parallel to one another and form a uniform stack. In the example shown, both radiator panels 2- 1, 2- 2 of a first radiator system 100, 200 are situated in the lower stack half, and both radiator panels of a second radiator system 100, 200 are situated in the upper stack half. The small thickness of the individual radiator panels 2, which can be in the range of a few millimeters or even below 1 mm, enables a particularly compact construction.FIG. 8 shows a perspective view of the cooling system 300 with the radiator panels 2 in their working state. FIG. 9 is a sectional view taken along line A-A, FIG. 10 is a sectional view taken along line B-B in this state.It can be seen that the radiator panels 2 of each radiator system 100, 200 lie in the same plane. This plane can be tilted differently from radiator system to radiator system with respect to the module plate 38. In the example shown, the planes of the different radiator systems 100, 200 lie tilted by an angle α 1= 135 ° or α 2= 45 ° with respect to the module plate 38 or its surface 40. This allows a particularly efficient heat radiation. In order that the radiator panels 2 maintain their position in their operating state shown, the hinges 30 and optionally also the hinges 42 have a corresponding latching mechanism.In addition, the satellite 47 is indicated in FIGS. 4, 5, 6, 7, 8, 9 to 10. It can be seen here that the module plate 38 extends over an entire side surface of this satellite 47, wherein other configurations are also conceivable. For example, the satellite 47 is a so-called "cube seat" having a size of 2×3 U. In this case, the module plate may extend over a side surface having a size of 1×3 U, another side surface having a size of 2×3 U, or another side surface having a size of 2×3 U.The satellite 47 has a control unit, not shown in detail, which is designed for the electrical control of the actuator unit 36 via the electrical interface 46. This allows the satellite 47, after a stable orbit has been reached, to put the radiator panels 2 from their transport state into their working state, so that the cooling system 300 can radiate heat from the satellite 47 into the world space.It is understood that the features described with reference to FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9-10 are not all essential, may be modified, or / and combined with each other. In particular, the examples described with reference to the figures can be embodied as described above with reference to the first, second and third aspects and vice versa. Further modifications are likewise conceivable and will become apparent to the person skilled in the art from the present disclosure.

Claims

Radiator system (100; 200) for a satellite (47), wherein the radiator system (100; 200) comprises at least one planar radiator panel (2) with an upper carrier layer (4) and a lower carrier layer (6) arranged substantially parallel to the upper carrier layer (4), wherein the radiator system (100; 200) further comprises a heat conducting layer (18) which extends at least in sections between the upper carrier layer (4) and the lower carrier layer (6) of the at least one radiator panel (2), and wherein the at least one radiator panel (2) comprises at least one connecting element (22) which is arranged between the upper carrier layer (4) and the lower carrier layer (6) and are connected both to the upper carrier layer (4) and to the lower carrier layer (6), such that the upper carrier layer (4) and the lower carrier layer (6) are fastened to one another at least via the at least one connecting element (22).Radiator system (100; 200) according to claim 1, wherein the at least one connecting element (22) is formed in a column shape and extends through the heat conducting layer (18) of the radiator system (100; 200).The radiator system (100; 200) according to any one of claims 1 to 2, wherein the at least one connecting element (22) consists of a first polymer.Radiator system (100; 200) according to claim 3, wherein the upper support layer (4) and the lower support layer (6) of the at least one radiator panel (2) each comprise a fabric penetrated by the first polymer.Radiator system (100; 200) according to one of Claims 1 to 4, wherein the heat-conducting layer (18) comprises a multiplicity of graphite layers (20) which are stacked one above the other.Radiator system (100; 200) according to one of claims 1 to 5, further comprising an upper flexible cover layer (24), which extends at least in sections between the upper carrier layer (4) and the heat conducting layer (18) of the at least one radiator panel (2), and a lower flexible cover layer (26), which extends at least in sections between the lower carrier layer (6) and the heat conducting layer (18) of the at least one radiator panel (2), wherein the at least one connecting element (22) extends both through the upper flexible cover layer (4) and through the lower flexible cover layer (6).Radiator system (100; 200) according to one of Claims 1 to 6, having two or more of the planar radiator panels (2-1, 2-2), wherein the radiator system (100; 200) is designed such that the radiator panels (2-1, 2-2) are stacked one above the other in a transport state and are arranged substantially in a plane in a working state, wherein adjacent radiator panels (2-1, 2-2) are each connected to one another in a foldable manner via at least one flexible connecting section (8), wherein the heat-conducting layer (18) extends through the at least one connecting section (8).Radiator system (100; 200) according to claim 7 and at least claim 4, comprising an upper fabric layer (10) which forms the fabric of the upper carrier layers (4) of the two or more radiator panels (2) and which extends through the at least one connecting portion (8), and a lower fabric layer (12) which forms the fabric of the lower carrier layers (6) of the two or more radiator panels (2) and which extends through the at least one connecting portion (8).Radiator system (100; 200) according to claim 8, wherein the upper fabric layer (10) and the lower fabric layer (12) are each penetrated by a second polymer different from the first polymer in the region of the at least one connecting portion (8).The radiator system (100; 200) according to any one of claims 7 to 9 and at least claim 6, wherein the upper flexible cover layer (24) and the lower flexible cover layer (26) each extend through the at least one connection portion (8).Radiator system (100; 200) according to claim 10, wherein in the area of the at least one connection section (8), the upper flexible cover layer (24) is the uppermost layer of the radiator system (100; 200) and the lower flexible cover layer (26) is the lowermost layer of the radiator system (100; 200).Cooling system (300) for a satellite (47) comprising a module plate (38) designed to be mounted on a satellite (47) and at least two radiator systems (100; 200) according to any one of claims 1 to 11 fixed to the module plate, wherein the radiator panels (2) of the at least two radiator systems (100; 200) form a single stack in their transport state.Satellite (47) comprising at least one radiator system (100; 200) according to any one of claims 1 to 11 or / and at least one cooling system (300) according to claim 12.

Images