Ejection unit

Description

[0001] The present invention relates to an ejection unit according to the preamble of claim 1 for at least one cuboid-shaped satellite, in particular for at least one picosatellite, comprising a housing closed by at least one door, in which a guide is provided for receiving a satellite. The guide has four parallel angle rails, the two legs of which are each arranged on two (adjacent) surfaces of an (imaginary) cuboid, wherein a clamping device is provided that releasably clamps a satellite in the guide.

[0002] Such an ejection unit is known from DE 10 2016 108 606 A1 or from KR 102 134 620 B1. In DE 10 2016 108 606 A1, the imaginary cuboid defined by the angled rails corresponds in its external dimensions to the external dimensions of the satellite, so that the satellite can be inserted between the angled rails. The satellites can be satellites according to the CubeSat standard. These are usually transported into orbit by a rocket and then ejected by the ejection unit. For ejection, the door of the ejection unit is opened and the satellite(s) are pushed out of the guide and thus released. However, the satellite and the ejection unit are exposed to great acceleration and loads during transport into orbit, particularly during rocket launch and when rocket components, such as a larger main satellite, are ejected.

[0003] CN 109 229 433 A discloses a fixation device for picosatellites, which are deployed using a robotic arm. The fixation device has two fixed and two pivoting holding elements, the latter of which are released by a spring when the satellite is deployed. Further ejection units for cuboid satellites are known from CN 106 081 170 A, US 943 448 6 B1, and US 2014 / 319283 A1.

[0004] It is therefore the object of the present invention to further develop an ejection unit according to the preamble of claim 1 in such a way that, with a simplified design, a secure and vibration-free fixation of a satellite in the ejection unit is ensured.

[0005] This object is achieved by the features of claim 1 and in particular by the fact that the clamping device has at least one tensioning mechanism which applies force to an angle rail exclusively in a direction which forms an angle bisector of this angle rail.

[0006] According to the invention, a satellite is clamped not at individual discrete points, but via an angled rail that is part of the guide, so that the clamping force applied to the satellite is evenly distributed across the satellite. Furthermore, the clamping force is applied diagonally rather than from two adjacent sides to the satellite, which allows for extremely high clamping and damping forces to be achieved with a single clamping mechanism, while taking the available installation space and component dimensions into account. This also significantly simplifies the design.

[0007] Advantageous embodiments of the invention are described in the description, the drawings and the subclaims.

[0008] According to a first advantageous embodiment, one of the angle rails can have a leg that is spaced outwards from the adjacent surface of the (imaginary) cuboid. In this embodiment, one of the angle rails rests against a satellite with only one leg, with the other leg of the angle rail being spaced from the adjacent side wall of the satellite. This ensures that the associated clamping device, which exerts a force in a diagonal direction, only transmits a clamping force perpendicular to one surface of the satellite. By using two clamping mechanisms of the type described above, i.e. with force applied diagonally on the one hand and perpendicular to the satellite on the other, even larger satellites (e.g. size 6U) can be reliably held and dampened without the forces of the clamping mechanisms working against each other.

[0009] If only one clamping mechanism is provided on an angle rail, it may be advantageous if the three remaining angle rails are fixedly attached to the housing. If two angle rails are equipped with clamping mechanisms, it may be advantageous if the other two angle rails are fixedly attached to the housing.

[0010] According to a further advantageous embodiment, the at least one clamping mechanism can comprise a carriage mounted on rollers, which supports a movable guide rail, which in turn is mounted on rollers of the carriage. Such a construction, which can advantageously comprise an inclined guide rail, allows the forces for clamping the satellite to be redirected and multiplied to achieve improved damping. The carriage has two roller systems: one roller system for low-friction movement of the carriage and a second roller system for moving the movable guide rail.

[0011] According to a further advantageous embodiment, a spring-loaded conical bolt can be provided, which secures an ejection carriage of the ejection unit in a locked position when the ejection carriage is in a pre-tensioned position. A spring-loaded bolt configured as a cone at its front end allows the bolt to slide automatically into a locked position when the ejection carriage is tensioned, as the cone of the bolt engages an opening in the ejection carriage. To prevent the conical bolt from being pushed out of its locked position by the pre-tensioned ejection carriage, a locking pin can be provided, according to a further advantageous embodiment, which holds the conical bolt in its locked position as long as the door is not almost fully opened.This ensures that the locking pin behind the conical bolt is only released when the door is fully or almost fully opened, so that the conical bolt moves out of its locked position and releases the ejection carriage so that it can be moved in the ejection direction by the force of a spring in order to eject a satellite.

[0012] According to a further advantageous embodiment, the at least one tensioning mechanism can comprise a push rod that engages the door and, in addition, a pull rod that can be actuated by the door and is actuated with force, for example, via a push rod that is pivotally connected to the door. In this way, the tensioning mechanism is tensioned by two independently operating mechanisms. When the door closes, it presses on the push rod to activate the tensioning mechanism. At the same time, the pull rod can apply a pulling force to the tensioning mechanism when the door is closed.

[0013] In the embodiment described above, it may be advantageous if the locking pin serves as a driver for the pull plunger at the end of the opening movement of the door, since this creates a redundant mechanism for moving the carriage in the opening direction.

[0014] According to a further advantageous embodiment, the ejection unit can have at least one rigid screw bolt that fixes an ejection carriage in a preloaded position on the housing. This simplifies loading the satellite and prevents unwanted forward movement of the tensioned ejection carriage. The screw bolt can be screwed into the ejection carriage from the outside through the housing, simultaneously ensuring that the carriage is at its rear stop, thus eliminating any play between the ejection carriage and the housing. Furthermore, such a screw bolt serves to prevent unwanted movement and unnecessary system loads before deployment in space.

[0015] According to a further advantageous embodiment, at least one fixing pin can be screwed into the door from the outside, which fixes a satellite arranged in the guide in the ejection direction without any play. Once a satellite has been inserted into the guide of the ejection unit and the door has been closed, the ejection carriage can be fixed to the housing in its pre-tensioned position as described above. If the fixing pin is then screwed in from the front of the door, any play between the satellite and the housing can be eliminated. According to a further advantageous embodiment, a plate-like anti-twist device can be provided for the fixing pin, through which the fixing pin is screwed on the one hand and which is secured to the outside of the door with a screw on the other. When the screw is loosened, the anti-twist device can still move slightly so that the fixing pin can be screwed into the door.However, when the screw is subsequently tightened, the anti-twist device tilts slightly, so that loosening the fixing pin is no longer possible due to frictional engagement in one of the fixing pin's threads.

[0016] According to a further advantageous embodiment, an emergency release can be provided on the outside of the door in order to open the door manually and / or without power during testing or servicing work.

[0017] According to a further advantageous embodiment, a tool-free door lock can be provided on the outside of the door to lock the door. It can be advantageous if the door lock can be operated with just one hand.

[0018] According to a further advantageous embodiment, the housing can be provided with service windows, each closed by a plate that is inserted into a retaining groove on one side and releasably secured on the other side by a clamping element that is captively attached to the housing. This allows for quick removal and re-attachment of the plate, as it merely needs to be inserted into its retaining groove and secured to the housing with the clamping element. The clamping element can, for example, be a nut that can be screwed onto a threaded pin, whereby the threaded pin can be provided with an end piece at its outer end that prevents the nut from becoming completely loose.

[0019] The present invention is described below purely by way of example using advantageous embodiments and with reference to the accompanying drawings. They show: Fig. 1a perspective view of an ejection unit; Fig. 2a longitudinal section along the line II-II of Fig. 1 with the doors open; Fig. 3 a longitudinal section corresponding Fig. 2 with the doors closed; Fig. 4 an enlarged view of the lower right area of Fig. 3 ; Fig. 5 a top view of the right lower ejection chute of Fig. 1 with the door open; Fig. 6 a plan view of an ejection unit according to a further embodiment with the doors open; and Fig. 7 an enlarged view of the lower right area of Fig. 6 .

[0020] Fig. 1 shows a perspective view of an exemplary embodiment of an ejection unit for a total of four cuboid-shaped satellites. The ejection unit comprises a likewise cuboid-shaped housing 10, in which a total of four ejection chutes, each for one satellite, are provided, which are labeled with the numbers 1 to 4. Each ejection chute is closed by a door 12, 14, 16, and 18, wherein the doors 12 and 14 are pivotable about an axis A and the doors 16 and 18 are pivotable about an axis B to enable ejection of a satellite. Each door is closed by a locking unit (not shown in detail), which can be unlocked by remote control.

[0021] How Fig. 1 As further illustrated, the housing is provided with a plurality of service windows 20, each closed with a plate 22. Each plate is inserted on one side into a retaining groove 24 formed on the housing and releasably fixed on its opposite side with a clamping element 26 which is captively fastened to the housing 10. In the illustrated embodiment, the clamping element is a nut screwed onto a threaded pin which is provided with a cap 28 on its upper side to prevent the nut from becoming loose. Each plate 22 is flexible and has a recess open to the outside on one side in the region of the clamping element, so that each plate 22 can be inserted under the nut 26 after being inserted into the retaining groove 24 and then screwed on.

[0022] In Fig. 1 It can also be seen that two fixing pins 30 are screwed into each door from the outside. These pins penetrate the door and serve to fix a satellite in the ejection direction without play. Each fixing pin 30 is screwed through an anti-twist device in the form of a plate 32, whereby the plate 32 can be screwed tight to the outside of the door with a screw 34. When the screw 34 is loosened, the fixing pin 30 can be screwed through the plate 32 into the door. When the screw 34 is then tightened, the plate 32 tilts within the thread of the fixing pin 30, thereby preventing the fixing pin from being unscrewed from the door.

[0023] Fig. 1 further shows that a door lock is provided on the outside of each door, formed by two pins 36 and 38 that can be pressed together without tools using the thumb and index finger to lock each individual door. Also provided on the outside of each door is an emergency release 40 that can be triggered using a tool.

[0024] A contact element 15 is provided on each door at the front of the housing 10. Its two contact pins are short-circuited when the door is fully opened. This allows for checking whether the door has fully opened during the satellite launch. Magnetic switches are also mounted on the housing 10, which can detect the complete closure of each door.

[0025] Fig. 5 shows a top view of part of the ejection unit of Fig. 1 , namely onto the ejection chute 4 with the door 18 open. As can be seen, a four-sided guide for the satellite is provided in the housing 10 to accommodate each satellite, which consists of a total of four angle rails 50, 52, 54 and 56, which are arranged parallel to each other, with two legs 50a, 50b, 52a, 52b, 54a, 54b and 56a, 56b being arranged on two adjacent surfaces of an (imaginary) cuboid Q, which in Fig. 5 is shown in dashed lines. This imaginary cuboid Q corresponds to the external dimensions of a satellite to be ejected and also extends the length of the satellite into the plane of the drawing. Thus, a satellite inserted into the guide formed by the angle rails 50 to 56 is guided and held on each outer side by two legs of the guide rails.

[0026] To releasably clamp the satellite in the guide, in the illustrated embodiment, the angle rail 54 is provided with a clamping device, which will be described in more detail below. This clamping device has a tensioning mechanism that applies force to the angle rail 54 exclusively in a direction W that forms an angle bisector of this angle rail. The force is therefore applied exclusively diagonally to the satellite. Since the three remaining angle rails 50, 52, and 56 are fixedly attached to the housing 10, the satellite can be securely clamped and held in the housing 10 by applying force to the angle rail 54 in the direction of the angle bisector.

[0027] Fig. 2 and Fig. 3 show a section along the line II-II of Fig. 1 each with open ( Fig. 2 ) and closed ( Fig. 3 ) Doors. How Fig. 2 As illustrated, the angle rail 54 is fastened to a movable link bar 60 which is mounted on rollers 62 of a carriage 64, which in turn is mounted on rollers 66 and can be moved in the ejection direction E. A pressure tappet 68 is used to move the carriage 64 against the ejection direction E. This tappet strikes the back of the door when the door 18 closes and moves the carriage 64 against the force of a spring 70 against the ejection direction E. By moving the carriage 64 against the ejection direction E, the rollers 62 move within their link guides 72, which extend obliquely with respect to the ejection direction E and, in the illustrated embodiment, have a gradient of six to one. If the carriage 64 is thus moved by six units, this causes the link bar 60 and thus also the angle profile 54 to move by one unit.Conversely, a force acting on the angle rail 54 (due to vibrations of the satellite) is reduced by a factor of six, which means that even severe vibrations can be well dampened.

[0028] Another component of the tensioning mechanism for the angle rail 54 is a pressure rod 74, which is connected at its front end to the door 18 via a joint 76, and which is connected at its rear end to a pull plunger 78, which pulls the slide 64 backward against the force of a spring 80, opposite to the ejection direction E. Connected to the pull plunger 78 is a locking pin 82, which can be pushed behind a spring-loaded conical bolt 84, which serves to secure an ejection slide 90, as described in more detail below.

[0029] How Fig. 5 shows, the ejection carriage 90 runs on all four angle rails 50 to 56, whereby an ejection spring 92 can cause the satellite to be ejected. To keep the ejection carriage 90 in its pre-tensioned rear position ( Figuren 2 bis 4 ), the conical bolt 84, which is provided with a cone on its front side, engages in a corresponding recess 85 in the ejection carriage 90. In Fig. 4 Here, a position of the ejection carriage 90 is shown in which the latter has not yet been fully moved into its rear end position (see also Fig. 2 ). However, if this is the case ( Fig. 3 ), the conical bolt 84 secures the ejection carriage 90 in the locked position of the conical bolt 84 by being pressed into the recess 85 of the ejection carriage 90 by its spring 87. Due to the conical shape of the conical bolt 84, the ejection carriage 90 can initially slide over the conical bolt 84 until it engages in the recess 85. In order to prevent the conical bolt 84 from becoming loose from its locked position, the conical bolt 84 is blocked at its rear end by the locking pin 82 as long as the door 18 is not completely or almost completely opened. Only when the door 18 has reached its open position has the pressure rod 74 moved far enough in the ejection direction E to release the conical bolt 84 at its rear. At this moment, the force of the ejection spring 92 causes the ejection carriage 90 to move in the ejection direction E, so that a satellite located on the angle rails can be ejected.During this movement, the locking pin 82 also serves as a driver for the pull plunger 78, ie the locking pin 82 presses from behind onto the pull plunger 78, so that the latter is moved in a forced manner in the ejection direction E if the force of a compression spring 94 (. Fig. 4 ) is not sufficient to move the carriage 64 in the ejection direction E.

[0030] To load a satellite into an ejection chute of the ejection unit described above, the ejection carriage 90 is first moved counter to the ejection direction E to the rear end of the ejection chute, compressing the ejection spring 92. In this position, the ejection carriage can then be secured to the housing 10 in the preloaded position using spring-loaded screw bolts. The ejection carriage 90 slides over the spring-loaded screw bolt until it engages a locking opening. This eliminates the need to manually hold the ejection carriage 90 in its preloaded position.

[0031] Subsequently, one or more screw bolts can be screwed through the housing into the ejection carriage 90 from the rear of the housing 10 in order to fix the ejection carriage 90 in its rearmost position, which simultaneously provides transport security. The satellite can then be inserted into the ejection chute, with its four outer edges being pushed into each angle rail 50 to 56. When the door 18 is subsequently closed, its inner side presses against the pressure tappet 68 and against the force of the spring 70, whereby the carriage 64 is moved backwards against the ejection direction E, which in turn moves the guide rail 60 due to the inclined guide rails in the direction W ( Fig. 5 ). At the same time, the pressure rod 74 is pushed rearward via the joint 76, whereby the carriage 64 is pressed rearward against the force of the spring 80 until the locking pin 82 engages behind the conical bolt 84. This locks the ejection carriage 90, allowing the satellite to be ejected after removing the rigid screw bolts and the spring-loaded screw bolts. In this state, the satellite is pressed by the force of the springs 70 and 80 from the angle rail 54 against the angle rails 50, 52, and 56. If the satellite exerts a force on the angle rail 54 and thus also on the guide bar 60 due to acceleration after the rocket launch, this force is redirected via the 6:1 gradient to the carriage 64, which travels six times as far as the guide bar 60. The movement of the carriage 64 is dampened by the two springs 70 and 80.For example, if they have a maximum force of 200 N, this means that the damping system dampens the satellite with 2400 N.

[0032] When the satellite is to be ejected in space, the door is unlocked by remote control, allowing it to open via springs (not shown in detail). This releases the push rod 68, and as the door opens, the push rod 74 begins to move forward in the ejection direction E, which also moves the pull rod 78 in the ejection direction E. As soon as the two springs 70 and 80 no longer exert force on the slide 64, the slide is pushed forward in the ejection direction E by the compression spring 94. This movement causes the slide bar 60 to retract via the inclined guide rails 72, whereby the satellite is no longer clamped in its guide.In the last degrees of opening angle of the door 18, the locking pin 82 is positively pulled out behind the conical bolt 84 by the pressure rod 74 so that it can be pushed away from the ejection carriage 90, whereby the ejection carriage 90 is moved in the ejection direction E by the ejection spring 92 so that the satellite is ejected.

[0033] Fig. 6 and Fig. 7 show a further embodiment of an ejection unit, wherein the same components are provided with the same reference numerals and only the differences are explained. Fig. 6 The ejection unit shown has a total of three ejection chutes, which can be closed by doors 12, 13 and 14, wherein the lower ejection chute, which can be closed by door 13, has twice the volume of an upper ejection chute. The two upper ejection chutes with doors 12 and 14 are designed as in the embodiment described above. The lower ejection chute with door 13 in turn has two stationary angle rails 50 and 52 as well as an angle rail 54, which is provided with a tensioning mechanism of the type described above. The fourth angle rail 55, which is located on the same lower side of the cuboid Q as the angle rail 54, is also provided with a tensioning mechanism of the type described above. However, the design of the angle rail 55 differs from that of the angle rail 54, which will be explained with reference to Fig. 7 is explained in more detail.

[0034] How Fig. 7shows, the angle rail 55 also has two legs 55a and 55b running at right angles to each other, wherein the leg 55b (horizontal in the figure) is in turn arranged on the lower surface of the cuboid Q. However, the other leg 55a (vertical in the figure) of the angle rail 55 is spaced outwards from its adjacent surface of the cuboid Q by a distance D. As a result, the angle rail 55 does not rest with its leg 55a on a satellite that fills the space of the cuboid Q. The tensioning mechanism of the angle rail 55 thus exerts a force F that runs parallel to the angle bisector of the angle rail 55. However, this force F only acts in the vertical direction on a satellite inserted into the ejection chute, since the leg 55a is spaced from the cuboid Q by the distance D and therefore does not touch the satellite.In this way, it is achieved that a satellite can be strongly dampened and well held in the ejection chute due to the two clamping mechanisms on the angle rails 54 and 55, but without the two clamping mechanisms working against each other.

Claims

1. An ejection unit for at least one cuboid satellite, said ejection unit comprising a housing (10) which is closed by at least one door (12-18) and in which a guide for receiving a satellite is provided, said guide comprising four parallel angled rails (50-56) whose two legs (52a-54b, 55b, 56a, 56b) are each arranged at two surfaces of a cuboid (Q), and a clamping apparatus which releasably clamps a satellite in the guide, wherein the clamping apparatus has at least one clamping mechanism which applies a force to one of the angled rails (54) exclusively in a direction (W) that forms a bisecting line of this angled rail (54).

2. An ejection unit according to claim 1, wherein one of the angled rails (55) has a leg (55a) which is outwardly spaced apart from the adjacent surface of the cuboid (Q) by a spacing (D).

3. An ejection unit according to claim 1 or 2, wherein two or three of the angled rails are fastened to the housing (10) in a stationary manner.

4. An ejection unit according to any one of the preceding claims, wherein the at least one clamping mechanism has a carriage (64) supported on rollers (62), said carriage (64) supporting a displaceable slot rail (60) which is supported on rollers (66) of the carriage (64).

5. An ejection unit according to any one of the preceding claims, wherein a spring-loaded conical bolt (84) is provided and secures an ejection carriage (90) in a blocking position when said ejection carriage (90) is in a preloaded position.

6. An ejection unit according to claim 5, wherein the conical bolt (84) is held in its blocking position by a locking pin (82) as long as the door (12-18) is not almost fully open.

7. An ejection unit according to any one of the preceding claims, wherein the at least one clamping mechanism has a push plunger (68) abutting the door (12-18) and a pull plunger (78) which can be actuated by the door (12-18) and which is acted on by force, for example, via a push rod (74) which is connected to the door (12-18) in an articulated manner.

8. An ejection unit according to claim 6 and 7, wherein, at the end of the opening movement of the door (12-18), the locking pin (82) serves as an entrainer for the pull plunger (78).

9. An ejection unit according to any one of the preceding claims, wherein at least one rigid screw bolt is provided that fixes an ejection carriage (90) in a preloaded position at the housing (10).

10. An ejection unit according to any one of the preceding claims, wherein at least one spring-loaded screw bolt is provided that fixes an ejection carriage (90) in a preloaded position at the housing (10).

11. An ejection unit according to any one of the preceding claims, wherein at least one fixing pin (30) is screwed into the door (12-18) from the outside and fixes a satellite without play in the ejection direction (E), said satellite being arranged in the guide.

12. An ejection unit according to claim 11, wherein the fixing pin (30) is screwed through a plate-like security against rotation (32) which is secured at the outer side of the door (12-18) with a screw (34).

13. An ejection unit according to any one of the preceding claims, wherein an emergency release device is provided at the outer side of the door (12-18).

14. An ejection unit according to any one of the preceding claims, wherein a door locking device (36, 38) which can be operated without tools is provided at the outer side of the door (12-18).

15. An ejection unit according to any one of the preceding claims, wherein the housing (10) is provided with service windows (20) which are closed with a plate (22) which is inserted at one side into a retaining groove (24) and which is releasably fixed at another side to a clamping element (26) which is captively fastened to the housing (10).