WO2004088150A2

WO2004088150A2 - Launcher assembly comprising a fixing device capable of isolating an equipment from a dynamic or pyrotechnic environment

Info

Publication number: WO2004088150A2
Application number: PCT/FR2004/050124
Authority: WO
Inventors: Eric Le Nechet; Fabien Frossard; Patrick Pass-Lanneau
Original assignee: Eads Space Transportation Sa
Priority date: 2003-03-26
Filing date: 2004-03-24
Publication date: 2004-10-14
Also published as: FR2853024B1; WO2004088150A3; FR2853024A1

Abstract

The invention concerns an assembly (100) comprising a main launcher structure (4) liable to be subjected to a dynamic and/or pyrotechnic environment as well as a payload and/or an equipment (2) mounted on said structure via a fixing device (1) capable of isolating at least partly the payload and/or the equipment from the dynamic and/or pyrotechnic structure. The invention is characterized in that the device (1) comprises reversible self-adhering means (20) including a first part and a second part capable of being engaged with the first part and of being released therefrom, the first and second parts being each provided with a plurality of teeth.

Description

ASSEMBLY FOR A LAUNCHER COMPRISING A FIXING DEVICE CAPABLE OF ISOLATING AN EQUIPMENT FROM A

DYNAMIC AND / OR PYROTECHNICAL ENVIRONMENT

DESCRIPTION

TECHNICAL AREA

The present invention relates generally to the field of assemblies comprising a main launcher structure capable of being subjected to a dynamic and / or pyrotechnic environment as well as a payload and / or equipment mounted on this same structure by the intermediate a fixing device capable of at least partially isolating the payload and / or the equipment from the dynamic and / or pyrotechnic environment.

The invention also relates to a launcher comprising such an assembly.

STATE OF THE PRIOR ART Several conventional embodiments are known of the prior art making it possible to fix fluidic, electrical equipment or mechanical parts on a main structure of a launcher capable of being subjected to a vibratory environment, or even allowing a payload to be fixed on this same structure.

Thus, these conventional embodiments can for example take the form of screws or rivets, providing a secure fixing of the various elements on the structure.

However, there are various pieces of equipment for which it is preferable, even essential, to carry out the fixing relatively late in the production cycle. This consequently leads to the need to carry out preliminary operations intended to authorize the carrying out of the attachment operations of the equipment, and therefore causes significant additional production costs. Furthermore, it is indicated that the equipment and / or the payloads mounted on the structure also undergo the dynamic and / or pyrotechnic environment in which this same main launcher structure is located, this particular environment resulting respectively in the presence of vibrations and significant shocks, which can in particular cause partial or total deterioration of these mounted elements.

As an indication, the dynamic environment encountered in flight by the main launcher structure generates vibrations of this structure at a frequency between about 5 and 2000 H _z . On the other hand, pyrotechnic shocks also generate vibrations of the main structure, at a frequency between around 2000 and 45000 Hz. Thus, the conventional embodiments of the prior art described above not being able, on their own, to isolate the elements from this environment, it is therefore necessary to provide additional protections or even to design equipment capable to withstand relatively severe operating conditions, in terms of vibrations at high frequencies.

In this way, in each of the proposed solutions capable of facing the particular environment encountered during the launcher flight situations and / or during pyrotechnic shocks, additional costs are also generated.

PRESENTATION OF THE INVENTION The aim of the invention is therefore to propose an assembly comprising a main launcher structure capable of being subjected to a dynamic and / or pyrotechnic environment as well as a payload and / or equipment mounted on this structure. by means of a fixing device, the assembly at least partially remedying the drawbacks mentioned above relating to the embodiments of the prior art.

More specifically, the object of the invention is to provide an assembly having a main launcher structure capable of being subjected to a vibratory environment, as well as a device for fixing a payload and / or a equipment capable of at least partially isolating the latter from a dynamic and / or pyrotechnic environment, and not requiring any prior operations to be carried out when wishes to assemble these elements late in the production cycle.

Finally, the invention also aims to propose a launcher comprising at least one such assembly.

To do this, the invention relates to an assembly comprising a main launcher structure capable of being subjected to a dynamic and / or pyrotechnic environment as well as a payload and / or equipment mounted on this structure via a fixing device capable of at least partially isolating the payload and / or the equipment from the dynamic and / or pyrotechnic environment. According to the invention, the fixing device comprises reversible hook-and-loop means comprising a first part as well as a second part capable of engaging with this first part and of disengaging from it, the first and second parts having each of a plurality of pins.

Advantageously, it has been noted that this type of reversible hook-and-loop means, having the aforementioned technical characteristics, was capable of damping vibrations whatever the vibration frequency. More particularly, it has been surprisingly observed that these hook-and-loop means make it possible to absorb vibrations at high frequencies such as those encountered by a main structure of a launcher subjected to a dynamic environment (in flight situation) and / or pyrotechnic (during pyrotechnic shocks occurring within the launcher).

In addition, during the tests carried out, it was also noticed that an attenuation factor of the order of -30 dB at 35 kHz, while the devices of the prior art guaranteed at best only a factor of -18 dB, in the same frequency magnitude.

Thus, the fixing device used in the assembly according to the invention is therefore entirely suitable for limiting the transmission of high frequency vibrations to sensitive elements, and is therefore largely suitable for at least partially isolating equipment and / or a payload of a main launcher structure subjected to a dynamic and / or pyrotechnic environment, such as that encountered respectively in flight and during pyrotechnic shocks.

The tests carried out firstly made it possible to observe that such reversible self-gripping means with spikes, therefore opening and reclosable, were capable of generating a dissipation of vibrations by friction.

Indeed, during the transmission of dynamic stresses to the equipment and / or the payload, the vibration energy is dissipated by friction between the pins of the first and second parts of the hook-and-loop means, these pins being naturally adapted for resist traction when nested together. In addition, a second important vibration attenuation factor has been detected. It is the diffraction of the shock wave, transmitted from the structure towards the equipment and / or the payload.

In fact, it has been observed that a plane shock wave propagating in the structure is diffracted by the pins of the hook-and-loop means, which then transmit only part of the energy towards the equipment and / or payload.

In addition, the reversible hook-and-loop means offered in the fixing device allow simple and rapid assembly of the equipment and / or the payload on the main structure of the launcher, this assembly being able, for example, to be achieved by manual pressure on the equipment, simultaneously generating the fitting of the pins and the engagement of the first and second parts. On the other hand, the equipment and / or the payload can be easily removed from the structure, by a disengagement of the first and second parts, this disengagement taking for example the form of a simple peeling. Finally, it is noted that with such damping provided by this device for fixing the assembly according to the invention, the equipment and payloads no longer necessarily need to be designed to withstand extremely severe operating conditions. In other words, more generally, it can be noted that the principle of the invention is based on the use of pins belonging to reversible hook-and-loop means for at least partially isolating a payload and / or equipment a dynamic and / or pyrotechnic environment applied to a structure on which is mounted this payload and / or this equipment by means of reversible hook-and-loop means. According to a preferred embodiment of the present invention, the first and second parts of the reversible hook-and-loop means are each secured to a layer of adhesive acrylic foam.

Advantageously, this layer of adhesive acrylic foam not only ensures the fixing of the first and second parts of the hook-and-loop means respectively on the structure and the equipment and / or the payload, but also generates a reduction in the transmission of vibrations, in addition to that coming from the factors already described above.

In this regard, it is noted that the acrylic foam alone makes it possible to constitute a conventional damper. Nevertheless, it is indicated that the damping phenomenon emanating directly from this layer of acrylic foam is substantially negligible compared to the damping provided by the friction between the pins and the diffraction generated by the latter. In addition, an additional damping factor comes from the fact that a shock wave transmitted by the structure first spreads in the layer of adhesive acrylic foam, then reaches the reversible hook-and-loop means and its plurality of pins, made for example of polyolefin.

Thus, the shock wave is partly reflected at each interface, and the multi-reflection between materials with different shock impedances generates significant attenuation of pyrotechnic shocks. In addition, it has also been observed that the energy of the shock wave is stored in the fixing device comprising the first and second parts as well as the layers of adhesive acrylic foam, then gradually re-diffused towards the equipment and / or the payload.

Furthermore, the invention also relates to a launcher comprising at least one such assembly. Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS

This description will be made with reference to the accompanying drawings, among which; FIG. 1 represents a schematic sectional view of a launcher assembly according to a preferred embodiment of the present invention, a device for fixing this assembly being interposed between a main launcher structure and an equipment, - FIG. 2 represents a sectional view taken along line II-II of FIG. 3, schematically enlarging the hook-and-loop means of the fixing device shown in FIG. 1,

FIG. 3 represents a sectional view taken along line III-III of FIG. 2, and

- Figure 4 shows a view similar to that of Figure 3, when the fastening device is subjected to dynamic stresses.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figure 1, there is partially shown an assembly 100 for launcher

(not shown) comprising a fixing device

1, the assembly being in accordance with a preferred embodiment of the present invention. Of course, without departing from the scope of the invention, the launcher which is also the subject of the present invention could comprise a plurality of assemblies such as that which will be described below. The assembly 100 therefore comprises a fixing device 1 which is intended to ensure the mounting of equipment 2 and / or of a payload on a main structure of the launcher 4, the elements 2 and 4 also belonging to the assembly 100. In addition, the device 1 is also able to at least partially isolate the equipment 2 and / or the payload from a dynamic and / or pyrotechnic environment to which this structure 4 is subjected during the flight phases of the launcher. , and during pyrotechnic shocks occurring at the same launcher. It is noted that in the following description, the element to be fixed on the main structure 4 will be called equipment 2, but it can of course be the payload, without departing from the scope of the invention. Furthermore, it is also specified that the equipment capable of being assembled on the main structure 4 can be of the fluidic, mechanical or electrical equipment type, such as fluid lines, reservoirs, valves, cabling, or even mechanical boxes.

Still with reference to FIG. 1, it can be seen that the fixing device 1 comprises a first part 6 comprising a support 8 as well as a plurality of pins 10 integral with the support 8, the support 8 and the pins 10 being preferably made in polyolefin. By way of indicative examples, the support 8 can be in the form of a plurality of strips or a single panel, and is of course capable of adapting to the geometry of the equipment 2 to be fixed.

In addition, on a surface of the support 8 opposite the surface carrying the pins 10, the device 1 is integral with a layer of adhesive acrylic foam 11, making it possible to establish the fixing between the support 8 of the first part 6 and the main structure 4.

Similarly, the fixing device 1 has a second part 12 comprising a support 14 as well as a plurality of pins 16 integral with the support 14 and substantially identical to the pins 10, the support 14 and the pins 16 being preferably made of polyolefin. It should be noted that in general, to obtain optimal cooperation between the first and second parts 6 and 12, the shape of the support 14 is substantially similar to that of the support 8.

In addition, on a surface of the support 14 opposite the surface carrying the pins 16, the device 1 is integral with a layer of adhesive acrylic foam 18, making it possible to establish the fixing between the support 14 of the second part 12 and 1 equipment 2.

Thus, the first and second parts 6 and 12 of the fixing device 1 form reversible hook-and-loop fastening means 20, insofar as these first and second parts 6 and 12 are capable of engaging one with the other by fitting their respective pins 10 and 16, and capable of disengaging by disengaging these same pins. As such, it is noted that the number, the arrangement and the shape of the pins 10 and 16 determine the force necessary for the disengagement of the first and second parts 6 and 12, this value corresponding in particular to a value for which the number of pins provided 10 and 16 is sufficiently important to cause, significantly, the phenomena of dissipation of vibrations by friction and by diffraction. In addition, this disengagement force value corresponds to a value making it possible to ensure a secure attachment of conventional equipment 2 to the main structure 4. In the preferred embodiment shown in Figures _^ , the pins 10 of the first part 6 are arranged in the form of rows, each row consisting of two lines of pins 10 located opposite two by two.

In the same way, the pins 16 of the second part 12 are arranged in the form of rows, each row being made up of two lines of pins 16 located opposite two by two. As can be seen jointly in FIGS. 2 and 3, the rows 22 of pins 10 and the rows 24 of pins 16 cooperate in pairs, so that each pin 16 of a first line of a row 24 is retained simultaneously by two pins 10 of each of the two lines of a row 22, and so that each pin 10 of a first line of a row 22 is held simultaneously by two pins 16 of each of the two lines of a row 24. In this case, it is specified that each pin 16 of the second line of row 24 concerned is only retained by two pins 10 of the first line of row 22, while each pin 10 of the second line of row 22 concerned is only retained by two pins 16 of the first line of row 24.

As can be seen clearly in Figure 3, the pins 10 and 16 each have a mushroom shape. In other words, each of these pins 10 and 16 comprises a rod 26, one end of which is integral with the support 8 or the support 14, and the other end of which carries a cap 28. Thus, when the pins 10 and 16 are fitted together and the first and second parts 6 and 12 are consequently engaged, the cap 28 of each pin 10 of a first line of a row 22 is simultaneously in contact with the cap 28 and one end of the rod 26 of each of the four pins 16 of the associated row 24. In the same way, the cap 28 of each spike 16 of a first line of a row 24 is simultaneously in contact with the cap 28 and one end of the rod 26 of each of the four pins 10 of the associated row 22. Note as can be seen in Figure 3 that when the first and second parts 6 and 12 are engaged, the contacts between the caps 28 of the pins 10 and 16 are located at a lower surface of these caps, in order to ensure retaining and maintaining the supports 8 and 14 relative to each other.

Still with reference to FIG. 3, it can be seen that the lower surface of the caps 28 is substantially planar, and that the upper surface preferably takes the form of a spherical cap.

However, it should be noted that the cooperation between the pins 10 and 16 as well as the shape of the latter which have just been described by way of illustrative examples could of course be different, without departing from the scope of the invention .

Figure 4 shows the first and second parts 6 and 12 when the stresses are transmitted to them. We can see in this figure that the supports 8 and 14 approach each other, as symbolically indicate the two arrows represented.

In this regard, it can be seen that each pin 10 initially in contact with several pins 16 rubs against the rod 26 of these pins 16 concerned, during the relative movement between the two supports 8 and 14. Likewise, during this movement relative between the two supports 8 and 14, each pin 16 initially in contact with several pins 10 rubs against the rod 26 of these pins 10 concerned. Naturally, the friction encountered during the longitudinal displacement of a given pin 10 or 16 takes place between the upper surface in the form of a spherical cap of the cap 28 of this same pin, and the rods 26 of the adjacent pins.

Consequently, part of the vibration energy transmitted from the main structure 4 of the launcher can be dissipated by friction.

On the other hand, the friction between the pins 10 and 16 causes a displacement of the latter, so that the energy coming from a shock wave propagating through the hook-and-loop means 20 is partially dissipated, after this shock wave was diffracted during its passage from the support 8 to the pins 10 of the first part 6.

Of course, various modifications can be made by a person skilled in the art to the launcher and to the assembly 100 which have just been described, only by way of nonlimiting examples.

Claims

1. Assembly (100) comprising a main launcher structure (4) capable of being subjected to a dynamic and / or pyrotechnic environment as well as a payload and / or equipment (2) mounted on said structure (4) by by means of a fixing device (1) able to at least partially isolate the payload and / or the equipment (2) from said dynamic and / or pyrotechnic environment, characterized in that the fixing device (1) comprises reversible hook-and-loop means (20) comprising a first part (6) as well as a second part (12) capable of engaging with and disengaging from said first part (6), the first and second parts (6,12) each having a plurality of pins (10,16).

2. Assembly (100) according to claim 1, characterized in that the pins (10,16) of said first and second parts (6,12) reversible hook-and-loop means (20) each have a mushroom shape.

3. Assembly (100) according to claim 1 or claim 2, characterized in that said first and second parts (6,12) reversible hook-and-loop means (20) are made of polyolefin.

4. Assembly (100) according to any one of the preceding claims, characterized in that said first and second parts (6,12) means Reversible hook-and-loop fasteners (20) are each secured to a layer (11,18) of adhesive acrylic foam.

5. Assembly (100) according to any one of the preceding claims, characterized in that it is capable of fixing fluidic, mechanical or electrical equipment on the structure capable of being subjected to a vibratory environment.

6. Launcher characterized in that it comprises at least one assembly according to any one of the preceding claims.