WO2007048161A1

WO2007048161A1 - Blind for a spacecraft

Info

Publication number: WO2007048161A1
Application number: PCT/AT2006/000439
Authority: WO
Inventors: Jovan Matovic; Berndt Ebner
Original assignee: Magna Steyr Fahrzeugtechnik Ag & Co Kg; Technische Universität Wien
Priority date: 2005-10-25
Filing date: 2006-10-25
Publication date: 2007-05-03

Abstract

Disclosed is a blind for a spacecraft. Said blind closes automatically in case of solar radiation in order to cover a heat exchanging surface of the spacecraft. The blind is formed by a number of lamellae (4), a longitudinal side (9) of which is pivotally fastened to base parts (5) that are fixed to the spacecraft. In order to improve the operational behavior while rendering the blind light, compact, insensitive to oscillations, and inexpensive, the lamellae are fastened to the base parts (5) by means of planar elements (14) made of a shape memory alloy. Said elements (14) change the curvature thereof when going through a transition range of the temperature, thus swiveling the lamellae. A first temperature range lies below the transition range while a second temperature range lies above the transition range. The lamellae (4) protrude substantially at a right angle from the heat transfer surface in the first temperature range while covering the heat transfer surface in the second temperature range.

Description

JALOUSIE FOR A ROOM VEHICLE

The invention relates to a Venetian blind for a spacecraft, which automatically opens or closes depending on temperature, to cover or cover a heat exchange surface of the spacecraft. It is formed by a number of slats, which are pivotally mounted with one longitudinal side attached to the spacecraft foot parts, being provided as a pivot drive with temperature change their shape changing parts.

The term spacecraft covers not only powered spacecraft, but also space stations and satellites that are subject to the same forces and vibrations when transported into space. In particular, in space stations and satellites is to ensure a regulated heat balance for on-board systems and crew. For this purpose, heat exchange surfaces are mounted on the outside of the spacecraft, which can absorb heat (in the form of radiation) from the surrounding space or release it into space. In the first case, cover the heat exchange surfaces of the spacecraft if no heat radiation In the second case, they can be covered when heat radiation occurs.

In known blinds, the individual slats of the blind are pivotally mounted about axes at the ends of bimetallic spirals are provided as a pivot drive, as described in a prospectus of the company "Orbital Technical Services Division", Beltsville (MD 20705) from 1997. This proven construction is relatively heavy, cumbersome, easy to assemble and susceptible to vibration, and its performance also leaves much to be desired.This fact that the bimetal is heated by thermal conduction and the relationship between its temperature and the angle of rotation of the lamellae is approximately linear is only an indication Due to the space required by the axes and bimetallic spirals, part of the heat exchange surface remains covered even when the blind is fully open, and therefore unused, and storage of the axes is problematic under ambient conditions.

It is therefore an object of the invention to overcome all these disadvantages and to provide a blind with improved performance, which is lightweight, space-saving, insensitive to vibration and cheap to manufacture.

According to the invention, the lamellae are fastened by means of planar elements made of a memory alloy (in the following short: memory elements) to the foot parts, which elements change their curvature when passing through a transitional region of the temperature and thus pivot the lamellae. Thus, initially the axes with their bearings and the bimetallic spirals fall away at their ends, which significantly reduces weight, space requirements and the susceptibility to vibrations. Because the lamellae can be pivoted by means of the memory elements distributed along their entire length, they can be pivoted. be considerably lighter. Thanks to their low mass and thanks to the thermal conduction of their feet, the memory elements rapidly change their temperature, allowing them to quickly cross the transitional temperature range. As a result, they quickly move from the fully open to the fully closed position. So their time behavior is much better than the systems known to date.

In a preferred embodiment, the memory elements in the first and second temperature ranges separated by the transition region assume different shapes on their own account, namely forming a flat surface in the first and an approximately right-angled knee in the second (claim 2). They deform in their own right in both directions. Therefore, two-way shape memory elements are also used, so that they do not require a spring to return to one or the other position

US 4,435,229 and 4,707,196, the contents of which are hereby incorporated by reference, together with a method for their initialization described in detail.

Preferably, they are fastened in their foot parts such that the first temperature region is below the transition region and the second above the transition region, wherein they protrude in the first temperature range substantially at right angles from the heat transfer surface and in the second cover the heat exchange surface (claim 3). Then they can radiate heat into space. Because they are stretched in the first (cold) temperature range, they practically do not obscure the heat exchange surface in the opened state. If, however, they were curved in this temperature range, they would shade a small portion of the heat exchange surface. In the cold State stretched memory elements make better use of the heat exchange surface.

For further improved utilization of the heat exchange surface overlap the lamellae in the heat exchange surface covering position with their free longitudinal sides (which are facing away from the foot parts) associated with the footboards long sides of the lamella located in front of it (claim 4). Thus, the memory elements are protected from the infrared radiation prevailing in space. This eliminates a protective coating of the memory elements, which would be problematic because of their strong Biegewechselbeanspruch-.

In preferred embodiments, the flat elements with their curvature inside abut against clamped in the foot parts spring elements and are provided on its curvature outside of the foot parts projecting stop which define the open position of the slats (claim 5). Due to the interaction of the actually redundant acting in the sense of opening spring elements with the attacks the open position of the slats is precisely defined. Although redundant, the spring elements counteract the fatigue of the memory elements (which can occur in very long missions). In addition, the spring elements also act as heat conductors to the memory elements, which further improves their timing behavior.

When the spring elements along the longitudinal side of the lamellae are arranged at certain intervals strips extending in the transverse direction to the free longitudinal sides of the slats (claim 6) and further formed from the foot parts facing the longitudinal side to the free longitudinal side as the slats supporting ribs are (claim 7), an auction is Fulfillment of the slats achieved, or the slats can be made much thinner. In any case, a significant simplification and reduction of manufacturing costs is achieved.

Alternatively, the spring elements may be arranged at certain intervals strips, which are united on the foot parts facing the longitudinal side of the slats to form a plate, which itself forms the blade (claim 8). Also, a significant simplification and reduction of manufacturing costs is achieved. The lamellae then need only be provided with a reflective coating, or they themselves consist of a material with a reflective surface.

A very advantageous refinement consists in that the width of the strip-shaped spring elements decreases from the foot parts to the longitudinal side of the slats facing the foot parts (claim 9). As a result, they adopt a circular bending line and thus attach themselves to the memory elements over a large area. This counteracts vibrations and improves the heat input into the memory elements.

Another conceivable variant is that the memory elements have a first and a second zone, wherein they can take different shapes in the first zone by the memory effect as a function of the temperature and are in the superelastic state in the second zone in which they even the slats form (claim 10). To achieve this, not the entire memory element but only a part of it is pretreated (initiated) as a memory element part.

A practical execution is that the foot parts for each slat or a series of slats (namely, if the slats in Longitudinal are interrupted) consists of a support rail and arranged at certain intervals feet, wherein the memory elements, the spring elements and the stops are clamped in the support rail and the feet are fixed to the spacecraft (claim 11). Thus, the slats can be prefabricated with their feet and the other components and easily attached to the outer wall of the spacecraft. For this purpose, then satisfy a few attachment points, where appropriate, the connection can be made by gluing. In addition, little heat is introduced from the heat transfer surface into the foot parts by the spaced feet. To compensate for different thermal expansions, the retaining rails can be displaceably guided in at least one foot in their longitudinal direction (claim 12).

For this purpose, the foot consists of a base part attached to the spacecraft, a torbogenförmigen head part and optionally a central part, wherein the sole part is fixed to the spacecraft, over its entire length has a slot for the passage of the retaining rail, and wherein the head part of the sole part clutching (claim 13). Thus, the holding rail is easy to install and it can be pre-assembled with a lamella with their foot parts and completely attached to the spacecraft, such as by gluing. The slot forms a firm clamping, which increases the flexural rigidity of the retaining rail.

An advantageous development of the foot is that the holding rail is traversed in the transverse direction by a bolt, and that the sole portion forms a bed in which the bolt is limited longitudinally guided (claim 14). Thus, the leadership of the retaining rail without affecting the displaceability is further improved and the occurrence of vibrations further difficult. In a more refined embodiment, the sole portion consists of two end walls and an intermediate block of smaller cross-section, which together with the central part forms the guide for the bolt and the block and the middle part of pawls forming legs of the head part are held together (claim 15). Thus, the head part can be easily clipped onto the sole part and the head part is also secured in the longitudinal direction.

In the following the invention will be described and explained with reference to figures. 1 is a view of a blind according to the invention, opened,

2: plan view in Fig. 1, in the closed position,

- Fig. 3: Section III-III in Fig. 2, enlarged,

FIG. 4 shows detail IV in FIG. 3 in a first embodiment, enlarged,

5 shows an exploded axonometric view of FIG. 4, FIG. 6 shows detail IV in FIG. 3 in a second embodiment, enlarged, FIG.

FIG. 7: Axonometric exploded view of FIG. 6, FIG.

FIG. 8 shows detail IV in FIG. 3 in a third embodiment, enlarged,

FIG. 9: detail IX in FIG. 5, FIG.

- Fig.10: a diagram of the effect of the memory element.

In Fig. 1, the surface 1 of a spacecraft is only indicated. A part of the surface is formed as a heat exchange surface 2 and over the entire surface covered by a total of 3 blinds when emitted from a celestial body 7 heat radiation is incident on them. The blind 3 consists of a number of mutually parallel slats 4, which are connected by means of a foot part 5 with the surface 1 or with the heat exchange surface 2 pivotally. The individual lamellae 4 can in their length _

8 ge be divided. The foot parts are fixed by means of feet 6 on the surface 1.

For the release of heat into space, the blind is in the open position shown in Fig. 1. As soon as it is illuminated by a celestial body 7, the parts of the blind 3 and possibly also the foot parts heat up, whereby the individual lamellae 4 are caused to pivot into the closed position shown in FIGS. 2 and 3.

In Fig. 2, the individual slats 4 in plan view are shortened (therefore the parallel dotted lines) shown. The lamellae 4, 4 'etc are rectangular, they have a free longitudinal side 9 and the feet 5 facing longitudinal side 10. In Fig. 3 is enlarged to recognize that the lamella 4, as well as all other parallel lamellae, the foot part 5 back a bending zone 8, which forms an approximately right-angled knee in the illustrated closed position. The free end 9 of the lamella 4 covers the bending zone 8 'and the foot part 5' of the subsequent further lamella 4 '. In the following, only a single lamella 4 or row of lamellae will be described in each case.

The bending zone 8 is formed by one or more flat elements of a memory alloy (hereinafter called memory elements). Memory alloys are known per se, for example from US Pat. Nos. 4,435,229 and 4,707,196, to which reference is expressly made. In these not only the composition of such alloys is given, but also various methods for initializing memory elements. Initialization describes procedures for their treatment that give them the desired behavior in the event of temperature changes. They consist of repeated changes in tempera- temperature and mechanical stress. In order to solve the problem underlying the invention, it has proved to be particularly advantageous to use so-called double-effect memory alloys Such double-acting memory alloys can, depending on their temperature, change their shape between two different forms on their own This will be discussed at the end of the description The memory elements are best treated to be flat in a low temperature range and to curl when heated, thus forming the approximately right-angled knee in the bending zone 8.

In Fig. 4 and 5, a plurality of strip-shaped memory elements 14 between the foot parts 5 and the actual lamella 4 are provided. At the curvature inner side of the memory elements 14, a spring element 15 is arranged, which forms a fold 16 forming the corresponding part of the memory element 14 in the foot part 5. At the top, the spring element 15 merges into a rib 17, on which the lamella 4 is fastened. The spring element 15, in cooperation with a stop 18, ensures that the opened lamella assumes a defined position. The spring element consists of a copper-beryllium alloy, or another elastic material.

The individual memory elements 14, spring elements 15 and stops 18 are united at their foot-side ends of a respective connecting strip 24, 25, 26 to a part. The connecting strips 24, 25, 26 together form a retaining rail 27, which are then connected by means of the feet 20,30 with the surface 1 of the spacecraft. By the connecting strips 24, 25, 26, the memory elements 14, spring elements 15 and stops 18 are easily produced by punching. It should be noted that the width of the slats 4 between their longitudinal sides 9, 10 is only in the order of a few centimeters. In Fig. 4 is still indicated by an arrow 28 zoomed 5 tet, which position the lamella 4 * occupies in the cold temperature range. The

Memory element 14 * is aligned in a plane, and abuts against the stop 18 *.

In Fig. 5 it is shown exploded. One sees that the width 15 "of the

10 spring elements 15 starting from the support rail 27, starting to the rib 17 decreases and that the rib has at its edges bent portions 29. The decreasing width causes a circular arc-shaped bending line of the spring element, which therefore lies flat against the memory element 14 in the bending zone 8.

15

The variant of FIGS. 6 and 7 (corresponding reference numerals are increased by 100) differs from the preceding embodiment primarily in that the spring elements 115 unite on the inner longitudinal side 110 of the lamella 104 in order to form the lamella 104 itself. For stiffening

20, the fin 104 is provided with criss-cross beads 117. It then only needs to be provided with a reflective coating on its surfaces. One speaks of a "first surface mirror" and a "second sur- face mirror". On the foot side, the spring element 115 again forms a U-shaped fold 116, which together with further reinforcing strips 124,

25 125, 126 forms a retaining rail 127, which is clamped in feet 120,130, to which the bolts 119 are provided.

The embodiment of FIG. 8 (the reference numbers are increased by 200) differs in that not the spring element 215 but the memory element 214 itself forms the lamella 204. For this purpose, it is necessary to treat the memory element 214 only in the bending zone 205 as a double-acting memory element and left untreated in the zone 206 so that it is in a superelastic state in this zone which shows no shape memory effect. The dividing line 209 corresponds to the longitudinal part of the lamella 204 facing the foot part.

FIG. 9 shows the clamping foot 130 of FIG. 7 in detail. It is designed so that it allows 27 thermal expansions in the longitudinal direction despite precise and vibration-damping guidance of the support rail. The base consists of a sole portion 31, a central portion 32 and a head portion 33. The sole portion is composed of two normal to the support rail 27 aligned end walls 35, 36 and in between a block 37 together, whose (invisible here) underside with the surface 1 of Spacecraft connected, for example glued, is. The block 37 forms approximately at half the height of the end walls 35, 36 a mating surface 39, from which an elongated bed 38 is worked out in which a fortified in the support rail 27 bolt 30 in the longitudinal direction of freedom of movement. The entire base portion 31 has a continuous slot 40 for receiving derjϊalteschiene 27. The middle part 32 sits with its nichtvisba- ren base on the mating surface 36 of the sole member and fits exactly between the two end walls 35, 36 of the sole member 31. He is of the head portion 33 pressed onto the sole portion 31. For this purpose, the arched head part consists of a bridge 43 and two elastic legs 44. The bridge 43 acts on the central part 32, the elastic leg 44 each end in an inwardly directed pawl 45, which surrounds the block 37 of the sole member 31.

Fig. 10 shows the behavior of the double-acting memory alloy. On the abscissa, the temperature in degrees Celsius and on the ordinate of the central angle of the bending zone 8 of a memory element is plotted. One recognizes a first low temperature region 60 which extends to approximately 50 degrees Celsius and a higher temperature region 61 which begins approximately at 75 degrees Celsius. In the transition region 62 in between The change in shape is between an angle of zero degrees (the memory element is straight) and an angle of 90 degrees (the memory element forms a right-angled knee). Due to the hysteresis, the curve 63, 64 has two branches 63, 64 in the transition region.

Claims

A spacecraft louver, which automatically opens or closes depending on the temperature, to expose or cover a heat exchange surface (2) of the spacecraft, formed by a number of louvers (4) which are attached to a longitudinal side (10) on foot members ( 5), whereby their shape-changing parts are provided as a function of temperature, characterized in that the lamellae (4; 104) are fastened by means of flat elements made of a memory alloy (= memory elements) (14; 114) to the foot parts (5; ), which elements (14; 114) change their curvature as they pass through a transition region of the temperature and thus pivot the lamellae (4; 104).

2. Venetian blind for a spacecraft according to claim I _5, characterized in that the memory elements (14, 114) in the through the transition region (62) separated first and second temperature ranges (60,61) take on their own power different shapes, in the first (60) forming a flat surface and in the second (61) forming an approximately right-angled knee (8).

Blind for a spacecraft according to claim 2, characterized in that the first temperature range (60) under the transition region (62) and the second (61) over the transition region (62), wherein in the first temperature range (60) substantially protrude perpendicularly from the heat transfer surface (2) and cover the heat transfer surface (2) in the second (61).

4. Venetian blind for a spacecraft according to claim 1, characterized in that the lamellae (4; 104) in the position covering the heat transfer surface (2) with their free longitudinal sides (9) connected to the foot parts (5; 105) longitudinal side (10 ) overlap a lamella (4 ') located in front of it.

5. Venetian blind for a spacecraft according to claim 3, characterized in that the memory elements (14; 114) abut with their curvature inside on in the foot parts (5; 105) clamped spring elements (15; 115) and on its outside curvature of the foot parts (5 105) projecting stops (18; 118) are provided which define the right-angled position of the lamellae (4; 104).

6. Venetian blind for a spacecraft according to claim 5, characterized in that the spring elements (15) along the foot portions (5) facing the longitudinal side (10) of the slats at intervals are arranged strips which extend in the transverse direction to the free longitudinal sides ( 9) of the slats (4) extend. (Fig. 4,5)

7. Venetian blind for a spacecraft according to claim 6, characterized marked, that the spring elements (15) of the foot parts (5) facing

Longitudinal side (10) to the free longitudinal side (9) of the slats (4) as the slats supporting ribs (17) are formed.

8. Venetian blind for a spacecraft according to claim 5, characterized in that the spring elements (115) are strips arranged at certain intervals, which are joined to a plate (104) on the longitudinal side (110) facing the foot parts (105), which forms the lamella itself. (Fig. 6,7)

9. Venetian blind for a spacecraft according to claim 6, characterized in that the width (15 ") of the spring elements (15) of the foot parts (5) to the foot parts facing longitudinal side (10) of the slats (4) decreases.

Venetian blind for a spacecraft according to claim 1, characterized in that the memory elements (214) have a first (205) and a second zone

(206), taking on a different shape in the first zone (205) by the memory effect and being in the superelastic state in the second zone (206) in which they themselves form the lamellae (204). (Fig. 8)

Blind for a spacecraft according to claim 5, characterized in that the foot parts (5) each lamella (4; 104) or row of lamellae consists of a retaining rail (27) and arranged at certain intervals feet (20; 30), wherein the memory elements (14; 114), the spring elements (15; 115) and the stops (18; 118) form a retaining rail (27) and the feet (20; 120,130) are fastened to the spacecraft.

12. Venetian blind for a spacecraft according to claim 10, characterized in that the retaining rails (27) are held displaceably in at least one foot (130) in its longitudinal direction.

13. Venetian blind for a spacecraft according to claim 12, characterized in that the foot (130) comprises a base part (31) attached to the spacecraft, an arched head part (33) and possibly a middle part (32), the sole part ( 31) on the spacecraft, a slot (40) for the passage of the retaining rail (27), and wherein the head part (33) clasps the sole part.

14. Venetian blind for a spacecraft according to claim 13, characterized in that the holding rail in the transverse direction of a bolt (30) is traversed, and that the sole portion (31) forms a bed in which the bolt (30) is guided limited longitudinally displaceable.

Venetian blind for a spacecraft according to claim 14, characterized in that the sole portion (31) consists of two end walls (35, 36) and an intermediate block (37) of smaller cross-section, which together with the (a) middle part (32) Guide for the bolt (30) forms and that the block (37) and the central part (32) of a pawl (45) forming thighs (44) of the head part (33) are held together.