Multiple hold-down and release device for spacecraft, and methods for releasing a spacecraft from a dispenser of a launcher and for installing a multiple hold-down and release device for spacecraft

Abstract

A multiple hold-down and release device for spacecraft includes a central structure including a central section with a cylindrical inner hole, an inner axial shaft insertable into the inner hole. A release bolt aligns with the inner axial shaft. A main bushing is partially arranged inside the inner hole and axially guided by guiding bushings on the main bushing and the inner hole. The main bushing includes a protrusion and internal retainer spring. Arms protruding from the central section are axially preloaded by a pusher opposite the central section. Connecting levers each connect to the end of the corresponding arm by the pusher. Hold-down assemblies on the periphery of the device each include a hold-down support and a fastener with conical contact surfaces, a torsion spring around a torsion spring shaft, and articulated with the corresponding hold-down support by the corresponding torsion spring shaft.

Claims

1. A multiple hold down and separation device for spacecraft, comprising: a central structure comprising: a central section with an inner hole with a cylindrical surface comprising an end stop, an inner axial shaft provided into the inner hole, the central section comprising a release bolt aligned with the inner axial shaft, a main bushing at least partly arranged inside the inner hole and axially guided by means of a guiding system comprising a guiding bushing on the main bushing and a guiding bushing on the surface of the inner hole, the main bushing comprising a protrusion on an outer surface, and a retainer spring provided inside the main bushing, and at least two arms protruding from the central section axially preloaded by a pusher at an end opposite the central section, a support connected to the central section of the central structure and comprising an attachment device, an actuator connected to the release bolt of the central section of the central structure, at least two connecting levers, each one of the connecting levers connected to an end of a corresponding arm of the central structure by the pusher, and at least two hold-down assemblies placed on a periphery of the multiple hold down and separation device, each of the at least two hold-down assemblies comprising a hold-down support and a hold-down both of the hold-down and the hold-down support comprising conical mating surfaces, each hold-down support comprising a torsion spring around a torsion spring axis, each corresponding lever articulated with a corresponding hold-down support through a corresponding torsion spring axis.

2. The multiple hold down and separation device for spacecraft, according to claim 1, further comprising an end stop on each hold-down support limiting an angle of rotation of the lever around the corresponding torsion spring axis.

3. The multiple hold down and separation device for spacecraft, according to claim 1, further comprising a latch on each hold-down support for retaining a corresponding lever.

4. The multiple hold down and separation device for spacecraft, according to claim 1, comprising two arms in the central structure and two hold-down assemblies.

5. The multiple hold down and separation device for spacecraft, according to claim 1, comprising four arms in the central structure and four hold-down assemblies.

6. The multiple hold down and separation device for spacecraft, according to claim 5, in which the hold-down assemblies are arranged in a rectangular configuration.

7. The multiple hold down and separation device for spacecraft, according to claim 5, in which the hold-down assemblies are arranged in a square configuration.

8. The multiple hold down and separation device for spacecraft, according to claim 1, comprising six arms in the central structure and six hold-down assemblies arranged in a hexagon configuration.

9. The multiple hold down and separation device for spacecraft, according to claim 1, wherein the actuator is a non-explosive actuator or a pyrotechnic actuator.

10. The multiple hold down and separation device for spacecraft, according to claim 1, wherein the arms protruding from the central section are integral parts of the central section or are separate parts joined to the central section.

11. A method to release a spacecraft from a dispenser of a launcher, the method using the multiple hold down and separation device for spacecraft of claim 1, wherein in a hold down position the spacecraft is attached to the dispenser at a plurality of discrete points by corresponding hold-downs, and the support comprising the attachment device and the hold-down supports are attached to the dispenser, the method comprising the following steps: electrically commanding from the launcher to activate the actuator by a line connecting the launcher and the actuator, releasing the release bolt and the central section of the central structure moves axially by elastic energy and the retainer spring until the protrusion of the main bushing contacts the end stop of the cylindrical surface of the inner hole, the arms of the central structure moving with the central section, releasing the connecting levers from the arms of the central structure and are rotated by elastic energy and the torsion springs, and releasing an end of each lever from the corresponding hold-down to unlock the corresponding hold-down, allowing separation of the spacecraft from the dispenser.

12. A method to install a multiple hold down and separation device for spacecraft, the method using the multiple hold down and separation device for spacecraft of claim 1, comprising the following steps: attaching the support and the hold-down supports to a dispenser of a launcher, attaching the hold-downs to the spacecraft, putting the central structure in a closed position with the release bolt attached to the actuator, and applying a torque to the pusher means placed at an end of each arm of the central structure.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a view of the multiple hold down and separation device of the invention attaching a spacecraft to the dispenser of a launcher (closed mode).

(2) FIG. 2 shows the elements of FIG. 1 once the spacecraft has been released from the dispenser (open mode).

(3) FIGS. 3 to 5 show several embodiments of the multiple hold down and separation device of the invention.

(4) FIGS. 6 to 8 show several embodiments of the central structure of the multiple hold down and separation device of the invention.

(5) FIG. 9 shows a detail of the multiple hold down and separation device of the invention in a closed mode.

(6) FIG. 10 shows a detail of the multiple hold down and separation device of the invention in an open mode.

(7) FIG. 11 shows a view of several elements of the multiple hold down and separation device of the invention in a closed mode.

(8) FIG. 12 shows a view of several elements of the multiple hold down and separation device of the invention in an open mode.

(9) FIG. 13 shows a detail of the connection between an arm of the central structure and a connecting lever.

(10) FIG. 14 shows a detail of the multiple hold down and separation device of the invention in a closed mode.

(11) FIG. 15 shows a detail of the multiple hold down and separation device of the invention in an open mode.

DETAILED DESCRIPTION OF THE INVENTION

(12) The invention discloses a device 1 used to hold down and release a spacecraft 27 at the desired number and location of discrete points by the opening of a single actuator 16 at the central point of the device 1.

(13) The multiple hold down and separation device 1 for spacecraft of the invention (illustrated, for instance, in FIGS. 3, 4 and 5) basically comprises several elements: a central structure 2, a support 14 connected to the central structure 2, an actuator 16 connected to the central structure 2, several connecting levers 17, and several hold-down assemblies 19 placed on the periphery of the device 1.

(14) FIG. 1 shows the multiple hold down and separation device 1 of the invention in a closed mode, attaching a spacecraft 27 to the dispenser 28 of a launcher. FIG. 2 shows the elements of FIG. 1 once the spacecraft 27 has been released from the dispenser 28 (i.e., when the multiple hold down and separation device 1 is in an open mode).

(15) The main elements of the central structure 2 can be seen in FIGS. 6, 7 and 8, corresponding to different embodiments. The central structure 2 comprises: A central section 3 with an inner hole 4 with a cylindrical surface comprising an end stop 5, an inner axial shaft 6 being provided into the inner hole 4. The central section 3 also comprises a release bolt 7 aligned with the inner axial shaft 6, a main bushing 8 at least partly arranged inside the inner hole 4 and axially guided by means of a guiding system comprising a guiding bushing 11 on the main bushing 8 and a guiding bushing 11 on the surface of the inner hole 4. The main bushing 8 comprises a protrusion 9 on its outer surface, and a retainer spring 10 is provided inside the main bushing 8. At least two arms 12 protruding from the central section 3. The arms 12 can be integral part of the central section 3 or can be joined to the central section 3 as separate parts (for instance, screwed to it). These arms 12 are axially preloaded by pusher means 13 at the end of the arm 12 opposite the central section 3. FIG. 13 shows an arm 12 and a connecting lever 17, with a tensioning pusher as pusher means 13.

(16) FIGS. 6 and 7 show a central section 3 with four arms 12, and FIG. 8 shows a central section 3 with six arms 12.

(17) The support 14 is connected to the central section 3 of the central structure 2 and comprises attaching means 15, suitable for attachment to the dispenser 28.

(18) The actuator 16 is connected to the release bolt 7 of the central section 3 of the central structure 2, when the device 1 is in the closed mode.

(19) Several types of actuator 16 are feasible to release the release bolt 7: Non explosive actuator named NEA (from EBAD company and others) that is a mechanism allowing to carry a very high tensile load by a release bolt 7 held in place by two separable spool halves which are in turn held together by tight winding of restraining wire. The restraint wire is held in place by redundant electrical fuse wires. When the nominal electrical current of 4 Amp during 25 ms is applied, the restraint wire unwinds allowing the spool halves to separate releasing the release rod and the associated preload. Separation nut or pyrotechnic actuator (from Pyroalliance, Chemring, EBAD and others) that maintains the preload of the release bolt 7 by threaded segments that are moved away by the pressure generated by pyrotechnic initiators upon an electric impulse of 5 Amp during at least 10 ms Other options to maintain and release the release bolt 7 as bolt cutters, frangible bolts and nuts are also feasible.

(20) The device 1 also comprises several connecting levers 17 (at least two ones). Each one of the connecting levers 17 is connected to the end of the corresponding arm 12 of the central structure 2 by means of the pusher means 13.

(21) The device 1 also comprises at least two hold-down assemblies 19 placed on the periphery of the device 1. Each hold-down assembly 19 comprises a hold-down support 20 and a hold-down 21, both of them with conical mating surfaces 22 (FIGS. 11 and 12). Each hold-down support 20 comprises a torsion spring 23 around a torsion spring axis 24. Each corresponding lever 17 is articulated with the corresponding hold-down support 20 through the corresponding torsion spring axis 24.

(22) In FIGS. 11 and 12 it can be seen that the hold-down support 20 additionally comprises an end stop 25 that limits the angle of rotation of the lever 17 around the corresponding torsion spring axis 24. It can also be seen that the hold-down support 20 additionally comprises a latch 26 suitable for retaining the corresponding lever 17, in order to prevent the lever 17 from retracting once it reaches its final position.

(23) The device 1 of the invention provides hold down and structural continuity between the spacecraft 27 and the launcher 28 at the desired number and location of discrete points (hold downs) and is released simultaneously by the activation of a unique actuator 16 at the central point.

(24) The device 1 comprises a central structure 2 with a number of arms 12 equal to the number of the desired hold down discrete points N axially preloaded with a force P.

(25) The number and the location of the discrete points can be selected for each mission by the only modification of the geometry of this central structure 12, being the rest of the pieces fully identical.

(26) This structure 12 is axially preloaded in a uniform way by applying torque sequentially to the tensioning bolts (pusher means 13) at the end of the arms 12. This preload is P/N.

(27) Each clamping system is composed by a connecting lever 17 in charge of the amplification and transmission of the preload from each arm 12 of the central structure 2 to the hold down 21. This amplification is achieved by the law of the lever pivoting along a bearing axis (the torsion spring axis 24). The mechanical advantage of the lever MA is therefore the ratio of distances from the bearing axis to where the input and output forces are applied to the lever 17. Then the preload introduced to the hold down 21 is MA?P/N. If the ratio of distances is selected in such a way that MA?N the resulting preload introduced to the hold down 21 is the same that the preload at the central point P. This allows to use the same actuator 16 for this device 1 as the one used for single hold downs, maintaining the commonality.

(28) Each hold down 21 comprises a classical cone to cone 22 preloaded to withstand both the lateral and axial external loads.

(29) In order to release a spacecraft 27 from a dispenser 28 of a launcher, a method can be used that uses a multiple hold down and separation device 1 for spacecraft of the invention, such that in a hold down position the spacecraft 27 is attached to the dispenser 28 at a number of discrete points by means of the corresponding hold-downs 21, and the support 14 that comprises the attaching means 15 and the hold-down supports 20 are attached to the dispenser 28. The method comprises the following steps: electrical command from the launcher to activate the actuator 16 by means of a line connecting the launcher and the actuator 16, the release bolt 7 is released and the central section 3 of the central structure 2 moves axially by means of its elastic energy and the retainer spring 10 until the protrusion 9 of the bushing 8 contacts the end stop 5 of the cylindrical surface of the inner hole 4, the arms 12 of the central structure 2 moving with the central section 3 (FIG. 2, FIG. 10), the connecting levers 17 are released from the arms 12 of the central structure 2 and rotate by means of its elastic energy and the torsional springs 23 (FIG. 12, FIG. 15), and the end of each lever 17 is released from the corresponding hold-down 21 to unlock the corresponding hold-down 21, allowing the separation of the spacecraft 27 from the dispenser 28 (FIG. 12, FIG. 15).

(30) In effect, the release of the device 1 starts with the activation of the actuator 16 (for instance, a separation nut). In an embodiment, this actuator 16 is activated in flight by an electrical signal coming from the launcher that is converted into a mechanical pressure inside the separation nut by standard pyrotechnic initiators. This pressure can be also introduced directly in the chamber of the separation nut with nitrogen gas for ground testing.

(31) The movement of the central structure 2 is axially guided by two low friction guiding bushings 11, 11 and pin/slots to prevent the rotation.

(32) At the end of the displacement the central structure 2 is mechanically stopped.

(33) An internal retainer spring 10 between the central structure 2 and the fixed point of the launcher keeps the central structure 2 at the open mode after the release.

(34) The opening of the central structure 2 relaxes the preload at the connecting levers 17 and therefore at the hold downs 21 and let the connecting levers 17 free to rotate along the bearing axis. The energy for this rotation movement comes mostly from their elastic energy. At the end of the rotation travel the connecting levers 17 are stopped by an end stop 25 (for instance, a teflon stopper) to reduce the shock of this impact. The connecting levers 17 are maintained at their open mode by two (left and right) torsional springs 23 at each bearing.

(35) The connecting lever 17 at the open mode provides enough clearance to allow the cones 22 attached to the spacecraft 27 to be safely released.

(36) This device 1 reduces the number of separation nuts, initiators, harness and separation management electronic controllers by a factor of N being N the desired number of discrete points, maintaining the preload P (if proper geometrical ratios are selected to have MA?N) and therefore the load capability of each hold down 21 and reducing the output shock to negligible levels: one single pyrotechnic device per spacecraft 27 located much far from the spacecraft interfaces.

(37) The actuator 16 can be activated on ground with cold gas hundreds of times without refurbishment. The pressure can be introduced directly in the chamber of separation nut with nitrogen gas for ground testing, so it is possible to perform a high number of low-cost tests with this device on ground to improve the final reliability of the design.

(38) In order to install a multiple hold down and separation device 1 for spacecraft, a method can be used that uses a multiple hold down and separation device 1 for spacecraft of the invention and comprises the following steps: attaching the support 14 and the hold-down supports 20 to the dispenser 28 of a launcher, attaching the hold-downs 21 to the spacecraft 27, putting the central structure 2 in the closed position with the released bolt 7 attached to the actuator 16, and applying a torque to the pusher means 13 placed at the end of each arm 12 of the central structure 2.

(39) Although the present invention has been fully described in connection with preferred embodiments, it is evident that modifications may be introduced within the scope thereof, not considering this as limited by these embodiments, but by the contents of the following claims.