IT202100013586A1 - Deployable ultra-thin spacecraft propellant tanks - Google Patents

Description

Description of the patent application for an industrial invention entitled: ?Ultra-thin deployable spacecraft propellant tanks"

Technical field of the invention

The present invention relates to a tank for a space vehicle. The tank ? capable of containing propellant. The present invention also relates to a space vehicle comprising one or more tanks.

Known art

Spacecraft are known to perform space flights. Space vehicles are very expensive to produce; therefore, in the space industry there? a need to reduce costs and production times of space vehicles, clearly without affecting efficiency and reliability? of the spacecraft being produced.

As known, the pi? spaceflight big problem? the weight of the vehicles; such a problem? also also one of the pi? great obstacles for the exploration of deep space, l? where the speed? necessary require quantity? of even greater propellants for each unit? of payload mass. Space vehicles are equipped with tanks designed to contain the propellant used to propel the vehicles; just the tanks are the major obstacle to? lightening the spacecraft when large quantities are needed? of propellants.

A solution to the spacecraft weight problem? represented by the use of balloon-type tanks, which use the internal pressure of the tank to guarantee its stability? structural. However, while these tanks are more? or less effective for traditional vehicles, they are not for a low-cost and/or rapidly re-usable commercial vehicle due to the following problems.

The main problems are related to their extreme delicacy (balloon tanks, if not pressurized, are in fact incredibly sensitive to accidental punctures, loads of all kinds, even minimal deformations) and they are also decidedly difficult to produce given their small thickness (especially on large vehicles). Being composed of a simple extremely thin layer of metal, the known balloon tanks are also devoid of any thermal insulation, both for the launch conditions and possibly for the flight through deep space; this problem also afflicts their reuse, making it difficult, if not impossible under certain conditions, for the survival of the tanks in a possible atmospheric re-entry.

The Applicant has therefore conceived a new tank structure, which allows to improve and lighten the known tanks for space vehicles.

Purposes of the invention

The main purpose of the present invention ? therefore that of providing a tank for a space vehicle capable of overcoming the drawbacks previously described in relation to the prior art.

Purpose of the present invention? therefore that of providing a fuel tank for a spacecraft that is remarkably light, strong, and easy and cheap to produce.

Additional purpose of the invention? the production of a tank which has much better thermo-mechanical characteristics than the current state of the art.

It is a further object of the present invention to provide a spacecraft fuel tank which can be used multiple times. times.

It also represents an object of the invention that of realizing a tank and a space vehicle which can optimize and improve its logistics.

These and other objects are achieved by a tank, a use of a tank, a spacecraft, a tank assembly, a method of manufacturing a tank, a method of operation of a tank, and a method of operation of a space vehicle according to the following description, the appended claims and the following aspects.

Summary of the invention

Aspects of the invention are described herein. If an aspect and / or a claim recalls, through specific dependence on one or more? other aspects or claims and/or by wordings such as the/the/the/the/said/a/i/e and similar, one or more? elements or steps introduced by another aspect or claim, such aspect(s) and/or such claim(s) may be taken in combination with each other.

The invention provides a collapsible fuel tank that can assume at least one reduced volume condition and one expanded volume condition thanks to the provision of a particular layered structure of the shell. The layered structure of the mantle that allows the deformability? of the cloak? partially in fabric and partially in plastic and/or polymeric and plastically deformable material.

Numbered aspects of the invention follow.

1. A tank for a space vehicle, the tank having a containing body adapted to contain propellant, the containing body defining an internal volume and having a layered structure, the layered structure providing at least:

- a main layer,

- a waterproofing layer arranged internally with respect to the main layer,

the containing body being configured to assume at least one first condition having a first internal volume and a second condition having a second internal volume different from the first internal volume.

2. Appearance according to aspect 1, where the main layer is? in fabric.

3. Appearance according to aspect 1 or 2, the internal volume being variable.

4. Appearance according to aspect 1 or 2 or 3, wherein the main layer being fabric.

5. Aspect according to one of the preceding aspects, the tank developing along a prevailing direction of development.

6. Appearance according to one of the preceding aspects, wherein the tank comprises a shell having said stratified structure.

7. Aspect according to one of the preceding aspects, wherein the main layer comprises a plurality of of fabric bands.

8. Tank for a space vehicle, the tank developing along a prevalent direction of development and having a containing body adapted to contain propellant, the containing body defining an internal volume and including a shell having a layered structure, the layered structure providing at least :

- a main layer, the main layer being made of fabric,

- a waterproofing layer arranged internally with respect to the main layer,

in which the internal volume ? variable and the containment body ? configured to assume at least a first condition having a first internal volume and a second condition having a second internal volume different from the first internal volume,

and wherein the main layer comprises a plurality of fabric bands.

9. Appearance according to one of the previous aspects, in which the waterproofing layer is? facing the internal volume.

10. Appearance according to one of the preceding aspects, wherein the shell defines a lateral surface of the containing body.

11. Appearance according to one of the previous aspects, in which the containment body is? configured to pass from the first to the second condition, or vice versa, by deformation of the stratified structure.

12. Appearance according to one of the preceding aspects, wherein the bands are fabric elements separated from each other, which are engaged in defining the skirt of the containment body.

13. Aspect according to one of the preceding aspects, wherein each band defines a longitudinal portion of the skirt.

14. Appearance according to one of the preceding aspects, in which the containment body has a solid of revolution conformation.

15. Appearance according to one of the previous aspects, in which the containment body is? substantially cylindrical or truncated cone.

16. Appearance according to one of the foregoing aspects, the layered structure having a single fabric layer.

17. Appearance according to one of the preceding aspects, wherein the single fabric layer has at least partially overlapping fabric bands.

18. Appearance according to one of the previous aspects, in which the waterproofing layer is? in direct contact with the main layer.

19. Appearance according to one of the previous aspects, in which the stratified structure is? at least partially deformable, in particular plastically deformable.

Appearance according to one of the foregoing aspects, the containing body being configured to switch between the first condition and the second condition by at least partial deformation, in particular plastic deformation, of the shell. 21. Appearance according to one of the previous aspects, in which the waterproofing layer is? deformable, in particular plastically deformable.

22. Appearance according to one of the previous aspects, in which the waterproofing layer is? in plastic and/or polymeric material.

23. Aspect according to one of the preceding aspects, wherein the waterproofing layer allows plastic deformation of the layered structure. 24. Aspect according to one of the preceding aspects, wherein adjacent bands are at least partially overlapped with each other.

25. Appearance according to one of the preceding aspects, in which the bands of the coat are superimposed on each other according to a given overlapping scheme, optionally to a given overlapping scheme recurring along the circumferential development of the jacket.

26. Appearance according to one of the previous aspects, in which the overlay pattern can? be continuous or alternating.

27. Appearance according to one of the preceding aspects, wherein the overlap scheme provides that a band has both longitudinal portions arranged internally with respect to the adjacent bands.

28. Appearance according to one of the preceding aspects, wherein the overlapping scheme provides that a band has a longitudinal portion disposed internally with respect to a first adjacent band and a longitudinal portion disposed externally with respect to a second adjacent band opposite with respect to the first adjacent band.

29. Appearance according to one of the preceding aspects, wherein the bands have longitudinal portions, the longitudinal portions of adjacent bands being at least partially overlapping each other.

30. Aspect according to one of the previous aspects, in which the bands develop parallel to each other.

31. An aspect according to one of the preceding aspects, wherein the bands are longitudinal bands.

32. Aspect according to one of the preceding aspects, wherein the bands develop longitudinally along, preferably parallel to, said main direction of development.

33. Appearance according to one of the preceding aspects, in which the fibers are arranged, in particular intertwined, according to a given texture or pattern.

34. Appearance according to one of the preceding aspects, wherein each fabric band comprises fibers intertwined along two or more? directions.

35. Appearance according to one of the preceding aspects, wherein the fibers constitute reinforcing material configured to give the stratified structure characteristics of structural resistance.

36. Appearance according to one of the previous aspects, in which the tank is? foldable type.

37. Aspect according to one of the previous aspects, in which the first condition is? a condition at reduced volume, the second condition ? an expanded volume condition.

38. Aspect according to one of the foregoing aspects, the second volume being at least three times, preferably at least five times, greater than the first internal volume.

39. Appearance according to one of the previous aspects, in which the stratified structure is? configured to withstand an internal pressure which ? function of the type of propellant intended to be contained in the tank.

40. Appearance according to one of the preceding aspects, wherein the layered structure comprises a thermal insulation layer configured to thermally insulate the tank under conditions of use, the thermal insulation layer being external to the main layer.

41. Appearance according to one of the previous aspects, in which the waterproofing layer is? able to make the stratified structure impermeable to propellant.

42. Appearance according to one of the previous aspects, in which the waterproofing layer is? made of waterproof propellant material.

The aspect according to one of the preceding aspects, wherein the thermal insulation layer and the main layer have a respective thickness, the thickness of the thermal insulation layer being smaller than the thickness of the main layer. 44. Appearance according to one of the previous aspects, in which the main layer is? in direct contact with the thermal insulation layer.

45. Appearance according to one of the previous aspects, in which the stratified structure is? configured to allow the passage of the containment body from the first condition to the second condition, and vice versa, a plurality? of times.

46. Appearance according to one of the preceding aspects, wherein the tank comprises a joining system configured to bond adjacent fabric bands together. 47. Appearance according to one of the preceding aspects, in which the joining system does not provide for the use of seams.

48. Appearance according to one of the previous aspects, in which the joining system ? free from welds and threads.

49. Aspect according to one of the preceding aspects, wherein the joining system comprises a plurality? of junction devices, preferably of the mechanical type, distributed at a plurality? of junction points of the containment body.

50. Appearance according to aspect 49, wherein each joining device being configured to constrain portions, in particular longitudinal portions, of adjacent bands together, said portions being located at the point where the joining device is? dislocated.

51. Appearance according to aspect 49 or 50, wherein each joining device comprises at least one constraint element suitable for constraining overlapping portions of adjacent bands together.

52. Appearance according to aspect 51, wherein the constraint element has a length at least equal to twice the thickness of a fabric band.

53. Aspect according to aspect 51 or 52, in which the element of constraint ? transversal, in particular orthogonal, to the portions of the adjacent bands which links and crosses both bands.

54. Appearance according to aspect 51 or 52 or 53, wherein said constraint element comprises a rivet.

55. The aspect according to one of the preceding aspects, wherein the waterproofing layer comprises waterproofing material.

56. Appearance according to one of the preceding aspects, in which the tissue presents a continuous development.

57. Appearance according to one of the previous aspects, the main layer defining the internal volume.

58. Appearance according to one of the previous aspects, in which the stratified structure is? a deformable layered structure.

59. Appearance according to one of the previous aspects, in which the stratified structure is? a plastically deformable layered structure.

60. Appearance according to one of the previous aspects, in which the deformability? of the deformable layered structure? due at least to the main layer of plastically deformable material.

61. Aspect according to one of the previous aspects, in which the first condition is? a reduced volume condition, the volume reduction being defined relative to the second condition.

62. Aspect according to one of the previous aspects, in which the second condition is? a larger volume condition, the volume being larger relative to the first condition.

63. Aspect according to one of the previous aspects, in which the main layer is ? at least partially made of material impermeable to spacecraft propellant, in particular to the propellant intended to be contained in the tank.

64. Appearance according to one of the previous aspects, in which the thermal insulation layer ? configured to withstand high temperatures, i.e. temperatures above 500 K.

65. Appearance according to one of the preceding aspects, wherein the thermal insulation layer comprises spherical elements.

66. The aspect according to aspect 65, wherein the spherical elements have a characteristic dimension at least one order of magnitude smaller than the layer thickness of the thermal insulation layer.

67. Aspect according to aspect 65 or 66, in which the spherical elements have a characteristic dimension in the order of magnitude of micrometres or nanometres. 68. Aspect according to aspect 65 or 66 or 67, wherein the spherical elements are silicon dioxide (silica) or aluminum trioxide (alumina).

69. Aspect according to one of aspects 65 to 68, wherein the spherical elements are spherules.

70. Appearance according to one of the preceding aspects, wherein the thermal insulation layer comprises a paint.

71. Appearance according to one of the previous aspects, in which the paint is? at least partially ceramic.

72. Appearance according to one of the previous aspects, in which the paint is? ceramic based.

73. Appearance according to one of the preceding aspects, wherein the layered structure has a thickness of between 10 and 7,500 micrometres, in particular between 20 and 5,000 micrometres.

74. Appearance according to one of the preceding aspects, wherein the main layer has a thickness of between 5 and 4500 micrometers.

75. Appearance according to one of the preceding aspects, wherein the stratified structure further comprises an external coating layer configured to act as a thermal interface between an external environment arranged outside the tank and the tank itself.

76. Appearance according to aspect 75, wherein the thermal insulation layer is? arranged between the main layer and the outer cladding layer.

77. Appearance according to aspect 75 or 76, wherein the outer coating layer is? material at least partially reflective to radiation which the tank? subjected under operating conditions, in particular at least partially reflecting infrared radiation and wavelength radiation in the visible range.

78. Aspect according to aspect 75 or 76 or 77, wherein in order to act as a thermal interface it is intended to manage, under operating conditions, a heat exchange between an external environment arranged outside the tank and the tank itself.

79. The aspect according to one of aspects 75 to 78, wherein the outer coating layer is? in reflective paint.

80. The aspect according to one of aspects 75 to 79, wherein the outer coating layer is? organic in nature.

81. The aspect according to one of aspects 75 to 80, wherein the outer coating layer is? inorganic in nature.

82. The aspect according to one of aspects 75 to 81, wherein the outer coating layer is the layer more exterior of the layered structure.

83. The aspect according to one of aspects 75 to 82, wherein the outer skin layer defines an outer surface of the tank.

84. Appearance according to one of the aspects from 75 to 83, wherein the external covering layer has a thickness in the order of magnitude of one or more? tens of micrometers.

85. The aspect according to one of aspects 75 to 84, wherein the thickness of the outer coating layer is? between 10 and 30 micrometres.

86. The aspect according to one of aspects 75 to 85, wherein the thickness of the outer coating layer is? about 20 micrometers.

87. Appearance according to one of the preceding aspects, wherein the stratified structure further comprises an internal lining layer facing the internal volume and configured to come into contact, under operating conditions, with the propellant housed in the tank.

88. Appearance according to aspect 87, the inner coating layer being a compatibility layer?, the compatibility layer? being compatible, from the point of view of chemical and/or physical interactions, with the propellant with which it is used? intended to make contact.

89. Appearance According to aspect 87 or 88, the internal coating layer has a thickness in the order of magnitude of one or more tens of micrometers.

90. Appearance according to aspect 87 or 88 or 89, wherein the thickness of the inner coating layer is? between 10 and 30 micrometres.

91. The aspect according to one of aspects 87 to 90, wherein the thickness of the inner coating layer is? about 20 micrometers.

92. The aspect according to one of aspects 87 to 91 , wherein the inner lining layer and the thermal insulation layer are engaged with respective facing surfaces of the main layer.

93. The aspect according to one of aspects 87 to 92, wherein the inner lining layer and the thermal insulation layer are in direct contact with respective facing surfaces of the main layer.

94. Appearance according to any of the preceding aspects, wherein the layered structure presents, proceeding from the internal volume to an external environment arranged outside the tank: an internal lining layer, the main layer, a thermal insulation layer and a layer of external cladding.

95. The aspect according to any of the foregoing aspects, wherein the tank comprises at least one interface device configured to interface the tank to another tank and/or to further components of the spacecraft wherein said tank is intended to be installed.

96. Appearance according to any one of the preceding aspects, wherein the fabric has a continuous development between interface devices, in particular between adjacent or consecutive interface devices arranged along a prevailing and/or axial direction of development of the cladding.

97. Aspect the aspect 95 or 96, in which the mantle develops along said prevailing direction of development between a first and a second extremity? opposing, at least one of these ends? being open, said at least one interface device being arranged at said at least one end? open and closing said extremity? open,

optionally both the first and the second end? of the shell are open, the reservoir comprising first and second interface devices configured to cover the first and second ends, respectively.

98. Appearance 95 or 96 or 97, wherein each interface device includes a socket configured to accommodate a? of the mantle of the containment body.

99. Aspect according to any of the previous aspects, in which each extremity? of the cloak? housed in a seat of a respective interface device.

100. The aspect according to any of the foregoing aspects, wherein each interface device comprises a first flange and a second flange disposed inwardly of the first flange at a given distance from the first flange, the distance defining a gap, the seat being defined in correspondence of the gap between the first and second flange.

101. Appearance according to any of the preceding aspects, wherein the first and second flanges develop circumferentially.

102. Aspect according to any of the previous aspects, in which the seat is? a circumferential location.

103. Appearance according to any of the preceding aspects, wherein the flanges of an interface device and the respective end? of the skirt are engaged with each other, preferably by means of engagement elements.

104. Appearance according to any of the preceding aspects, wherein the engaging members are threaded members.

105. Appearance according to any of the preceding aspects, wherein the flanges of each interface device and the respective end? of the shell are provided with holes, preferably threaded holes, in correspondence with which the threaded elements are engaged.

106. An aspect according to any one of the preceding aspects, wherein each interface device provides a sealing material configured to prevent propellant leakage.

107. Aspect according to any one of the preceding aspects, wherein the sealing material comprises a gasket, preferably chemically compatible with the propellant intended to be housed in the tank.

108. The aspect according to any of the preceding aspects, wherein the tank comprises a propellant distribution line or a portion of a propellant distribution line traversing at least partially said internal volume, the propellant distribution line defining a conduit in which can ? flowing propellant.

109. Aspect according to any of the preceding aspects, wherein the propellant distribution line is? at least partially in the same material as the matrix.

110. The aspect according to any one of the preceding aspects, wherein the propellant distribution line has a layer of the same material as the matrix.

111. An aspect according to any of the preceding aspects, wherein the propellant distribution line has a layered structure having:

- said layer in the same material as the matrix,

- an internal lining layer adapted to come into contact with the propellant, the internal lining layer being arranged internally with respect to said layer and facing the duct,

- an outer coating layer adapted to come into contact with the propellant, the outer coating layer being disposed outside said layer.

112. The aspect according to any of the foregoing aspects, wherein the inner cladding layer and the outer cladding layer being compatibility layers, each compatibility layer? being compatible, from the point of view of chemical and/or physical interactions, with the propellant with which it is used? intended to make contact.

113. The aspect according to any of the preceding aspects, wherein the tank comprises a pressurization system configured to cause passage of the containing body from the first condition to the second condition, optionally the pressurization system being configured to cause passage of the containing body from the first condition to the second condition by introducing fuel into said internal volume.

114. Aspect according to any of the preceding aspects, in which the containing body is? configured to switch from the second condition to the first condition upon release of the tank's internal pressure.

115. Appearance according to any of the preceding aspects, in which the layered structure develops continuously along the development of the coat.

116. Appearance according to any of the previous aspects, in which the tank is? pressure-reinforced type.

117. An aspect according to any of the foregoing aspects, wherein the container has a structure whose resistance to loads is derived primarily or entirely from shell tension.

118. Use of the tank according to any of the foregoing aspects and/or the appended tank claims for containing propellant.

119. Tank assembly comprising:

- a first tank,

- a second tank,

each tank being in accordance with any of the foregoing aspects and/or the appended tank claims,

the first and second tanks being coupled.

120. Aspect according to aspect 119, each reservoir comprising an interface portion configured to couple the first and second reservoirs together. 121. A space vehicle including at least one tank for containing propellant according to any of the foregoing aspects and/or the appended tank claims.

122. Spacecraft comprising:

- an elongated box-shaped body developing along a prevailing direction of development,

- at least one tank according to any of the preceding aspects and/or of the appended tank claims, the tank being configured to contain propellant.

123. Appearance according to aspect 122, said at least one reservoir at least partially defining the box-like body.

124. Appearance according to aspect 122 or 123, wherein the vehicle comprises first and second tanks, each tank according to any one of the preceding aspects and/or the appended tank claims and defining a respective box-like body portion .

125. Appearance according to aspect 124, wherein the first and second reservoirs are arranged consecutively along the prevailing direction of development.

126. The aspect according to one of aspects 122 to 125 , wherein the vehicle further comprises a drive section.

127. Appearance according to? Appearance 126, in which the tank ? in fluid communication with the drive section so as to supply, under operating conditions of the spacecraft, the drive section with propellant contained in said at least one tank.

128. The aspect according to one of aspects 122 to 127 , wherein the skirt of the containment body forms an outer wall of the box-like body.

129. The aspect according to one of aspects 122 to 128, wherein the vehicle comprises at least one propellant distribution line traversing at least partially the internal volume of the tank.

130. The aspect according to one of aspects 122 to 129, wherein the vehicle further comprises:

- a further tank adapted to house propellant, in particular a further tank in accordance with any of the preceding aspects and/or of the attached tank claims, and

- at least one component which ? intended for the propellant housed in said additional tank,

the tank being interposed between the further tank and said component, the propellant distribution line placing said further tank in fluid communication with said component.

131. Appearance according to aspect 130, in which said at least one component ? or comprises a motor, preferably a rocket motor.

132. Aspect according to one of aspects 122 to 131, in which the vehicle is? a single stage vehicle.

133. Method of manufacturing a tank according to any of the preceding aspects and/or the appended tank claims, the method comprising at least the steps of:

- arranging fabric bands to form a fabric layer, the fabric layer forming a shell of a tank containment body,

- engaging a waterproofing layer to the fabric layer in such a way that the waterproofing layer is internal to the fabric layer.

134. Appearance according to aspect 133, wherein the step of arranging fabric bands to form a fabric layer comprises engaging fabric bands together, preferably by means of a mechanical joining system.

135. The aspect according to aspect 134, wherein the step of engaging fabric bands together comprises overlapping longitudinal portions of adjacent fabric bands.

136. The aspect according to aspect 134 or 135, wherein the step of engaging fabric bands together comprises engaging adjacent fabric bands together, preferably by one or more bands of fabric. joining devices.

137. The aspect according to aspect 134 or 135 or 136, wherein the step of engaging fabric bands together does not provide for sewing the fabric bands together.

138. The aspect according to one of aspects 133 to 137, wherein the method of manufacturing a tank does not provide for using or making seams for making the skirt of the tank.

139. The aspect according to one of aspects 133 to 138, wherein the method comprises the step of engaging an interface device at each end? opening of the cloak.

140. Method of operation of a tank comprising at least the following steps:

- providing at least one tank according to any of the preceding aspects and/or the attached tank claims, the tank being in the first condition or in the second condition,

- determining the transition of said tank from the first condition to the second condition or vice versa.

141. Method of operation of a spacecraft comprising at least the following steps:

- providing at least one spacecraft according to any of the preceding aspects and/or of the appended spacecraft claims, the spacecraft being in a first reduced-volume condition or in a second expanded-volume condition,

- determining the transition of said spacecraft from the first condition to the second condition or vice versa.

142. The aspect according to aspect 141, wherein the step of determining the transition of said spacecraft from the first condition to the second condition or vice versa comprises determining the transition of each tank of the spacecraft from the first condition to the second condition or vice versa.

143. The aspect according to aspect 140 or 141 or 142, wherein the step of bringing about the transition of said or each tank from the first condition to the second condition or vice versa comprises plastically deforming the layered structure.

144. The aspect according to aspect 143, wherein the step of plastically deforming the layered structure provides plastically deforming the main layer of the layered structure.

145. Aspect according to any of the previous aspects, in which the tank is? ultra-thin type.

146. Appearance according to any of the foregoing, in which the mantle of the containment body is seamless.

Conventions and definitions

It should be noted that in the following detailed description corresponding parts are indicated with the same reference numerals. The figures could illustrate the object of the invention through non-scale representations; therefore, parts and components illustrated in the attached figures and relating to the object of the invention could relate exclusively to schematic representations. In the context of this discussion, the use of terms such as ?above?, ?superior?, ?superiorly?, ?below?, ?inferior?, ?inferiorly?, ?side?, ?lateral?, ?laterally?, ? inside?, ?inside?, ?outside?, ?outside?, ?horizontally?, ?horizontally?, ?vertically?, ?vertically?, ?front?, ?front?, ?rear?, ?rear?, ?right? , ?sinister?, similar terms and relative variants refer, unless otherwise specified, to at least one spatial orientation that the object of the invention can? assume in conditions of use. Unless otherwise specified, the terms ?condition? or ?configuration? may be used interchangeably in the context of this discussion

In the context of this treatment are applicable, if necessary and unless otherwise indicated, one or more? of the following definitions and conventions:

- for ?tank? does it mean any container configured and/or designed to contain one or more? propellants, preferably a specific propellant;

- for ?external environment? it means the environment outside the tank;

- for ?internal volume? we mean the volume defined by the tank, in which pu? be housed propellant;

- where applicable, for expressions such as ?internal?, ?internally?, ?external?, ?externally? and similar means the relative provision of one or more? elements or layers with respect to another element or layer along a defined direction between the internal volume and the external environment of the tank; with reference to the tank, overall, the inside corresponds to the internal volume defined by the containment body and the outside corresponds to the external environment defined outside the tank. The internal volume? therefore defined inside the stratified structure of the tank and the external environment? defined outside the layered structure;

- for ?waterproofing layer or material? means a layer or material impermeable to the propellant intended to be contained in the tank;

- for ?main layer? means the layer of the layered structure configured to provide structural strength to the containing body. In conditions of use of the tank, the main layer provides support and allows the distribution of the loads acting on the containment body.

Brief description of the drawings

To better understand the invention and appreciate its advantages, some of its embodiments are described below, by way of non-limiting example, with reference to the accompanying figures, in which:

Figure 1 illustrates a tank according to an embodiment of the invention;

Figure 2 illustrates a tank assembly equipped with a first tank and a second tank according to an embodiment of the invention; the tank assembly has a propellant distribution line configured to distribute propellant through the first tank;

figure 3 illustrates a top view, in section, of the shell of the tank according to the present invention, where is it? shown the stratified structure in which a first and a second band of fabric of the main layer are mutually engaged by means of a joining device;

Figure 4A illustrates a tank according to the present invention in a first reduced volume condition;

FIG. 4B illustrates the reservoir of FIG. 4A after passing, upon deployment by pressurization, into a second expanded volume condition;

Figure 5A illustrates a space vehicle comprising two tanks according to the invention; both tanks are in the first reduced volume condition;

FIG. 5B illustrates the vehicle of FIG. 5A in which, upon deployment by pressurization, the tanks are transitioned into the second expanded volume condition.

Detailed description of embodiments of the invention Tank

A tank according to the invention? indicated as a whole in the figures with the reference number 1. The tank 1 ? conceived for a spacecraft 100 and ? preferably intended to house, in its internal volume, propellant.

The tank has a containment body 2 which develops along a prevalent development direction D?. The containment body 2 defines the internal volume of the tank 1 and ? the component of the tank 1 adapted to contain propellant. The containment body 2 ? configured to assume at least a first condition having a first internal volume (reduced volume) and a second condition having a second internal volume (expanded volume) greater than the first internal volume. Tanks 1 in the first condition are illustrated in figures 4A and 5A , while tanks 1 in the second condition are illustrated in figures 4B and 5B. The second condition at expanded volume ? preferably the operating condition of the tanks 1. The sequence of figures 4A and 4B shows the passage of the tank 1 from the reduced volume condition to the expanded volume condition; this passage and the reverse passage occur substantially respectively by unfolding and folding of the containment body 2. In the first condition, the containment body 2 has a reduced internal volume; in a compacted condition and pu? be stored, for example after its use, occupying a small volume. There? makes possible the storage in a reduced volume of the vehicle 100 in which the tank 1 ? integrated; in this regard, see figure 5A, illustrating a vehicle 1 equipped with two tanks in accordance with the invention. To make the volume variation of the tank 1 possible, the containment body 2 ? at least partially deformable; this deformation occurs both during folding and unfolding of the containment body 2. The containment body 2? structured to pass from the first condition to the second condition, and vice versa, a plurality? of times; There? makes it possible to reuse the tank 1. The tank 1 also has a passage section 3, which ? suitable under operating conditions to allow the outflow of propellant from the tank 1. The passage section can? be defined on the containment body 2; as shown in figures 1 and 2, the passage section 3 can? have a passage hole having a diameter D1 smaller than the diameter D2 of the containment body 2.

The containment body 2 preferably has a solid of revolution conformation, the axis of revolution of which is ? consisting of the prevailing direction of development D?. In the attached figures, the containment body 2 has a substantially cylindrical shape having a diameter D2.

The containment body 2 comprises a shell 4. As shown in the accompanying figures, the shell 4 defines the side wall of the tank 1. In the embodiments in which the containment body 2? cylindrical, skirt 4 defines the side wall of the cylinder. Cloak 4? deformable; the deformability? of the shell 4 allows the containment body 2, and therefore the tank 1, to vary its internal volume as described above. Tank 1? type press-reinforced, ie has a structure, which will? described below, whose resistance to loads derives mainly or entirely from the tension of the components, in this case from the lateral wall of the containment body 2, constituted by the shell 4. The tension of the shell 4 ? generated starting from the pressure difference between the volume inside the shell 4 itself and the surrounding environment; one or more special pressurization systems 12 maintain this difference during the drainage of the propellants.

Coat 4 develops along the prevailing direction of development D? between a first end? 4th and a second end? 4b longitudinally opposite. In the accompanying figures, in which the main direction is development D? ? vertical, the first and the second extremity? 4a, 4b are shown respectively as the ends? lower and upper mantle 4. One or both ends? 4a, 4b can be opened; in figure 1 ? shown an embodiment in which both ends? 4a, 4b are open. At each end? 4a, 4b open the tank 1 pu? provide an interface device 5, which ? action to close the? extremity? open 4a, 4b to which ? engaged. In the embodiments in which the containment body 2 is cylindrical, can be expected one or more? interface devices 5, each of which therefore represents the component defining the base wall (bottom) or the upper wall (cover) of the cylinder, which ? engaged to the side wall of the cylinder defined by the skirt 4. Further details of the interface device 5 are detailed below.

The structure of the cladding 4, which allows the deformability? of the shell 4 itself and therefore of the containment body 2. The shell 4 has a stratified structure. The layered structure? deformable to allow the volume variation of the tank 1. In particular, the stratified structure? at least partially plastically deformable, so that the containing body 2 can assume the first condition with reduced volume and the second condition with expanded volume; the transition between these conditions ? allowed by a plastic deformation of the stratified structure. The at least partial plastic deformation of the stratified structure allows the cladding 4 to assume a given condition, such as the reduced volume condition or the expanded volume condition, and to maintain this condition following the release of the force which caused it to assume such condition. For at least partial plastic deformation of the layered structure you can? to understand that at least one layer of the stratified structure is plastically deformed in the transition from the first condition to the second condition and vice versa.

The plastic deformation of the shell 4 in the transition from the first condition to the second condition can? be determined by a pressurization system; conversely, the plastic deformation of the shell 4 in the transition from the second condition to the first condition can? take place following the exhaustion of the propellant in the tank 1 and the release of the internal pressure of the tank 1 (ie the pressure defined in the internal volume); substantially, under its own weight, the tank 1 autonomously returns to its original condition with reduced volume.

The layered structure allows you to repeat a plurality? of times the passage from the first to the second condition and vice versa, in such a way as to make the tank 1 reusable a plurality? of times. This deformation of the stratified structure? possible by means of the examples of stratifications which are described below, which provide possible embodiments of the tank 1 according to the invention.

The layered structure can have a thickness of between 10 and 7,500 micrometres (?m), in particular between 20 and 5,000 micrometres. This thickness of the stratified structure of the shell 4, in relation to the diameter of the tank 1, makes the tank 1 itself ultra-thin.

The layered structure comprises at least two layers, in particular at least one main layer 6 and a waterproofing layer 7. The main layer 6? the layer responsible for the structural strength of the shell 4 and, consequently, of the containment body 2 of the tank 1. Internally with respect to the main layer 6, is it? a waterproofing layer 7 is provided. As illustrated in figure 3, the waterproofing layer 7 is provided. engaged at the internal surface of the main layer 6, in particular in direct contact therewith. The waterproofing layer 7 is described below, and then the main layer 6 is detailed.

The waterproofing layer 7 ? made of material impermeable to the propellant intended to be contained in the tank 1 and, by preventing the passage of the propellant, it allows the tank 1 to be watertight. The waterproofing layer 7 ? appropriately chosen on the basis of the propellant to be introduced into tank 1. The waterproofing layer 7 ? made of plastically deformable material, which allows the previously described repeatable deformation of the layered structure of the shell 4. The waterproofing layer 7 is made of plastically deformable material. preferably the only plastically deformable layer of the layered structure which is plastically deformed in the transition between conditions of the tank 1; thus, the waterproofing layer 7 ? configured to manage the deformation load of the tank 1 (bending load in the passage from the second to the first condition and unfolding load in the passage from the first to the second condition), while the main layer 6 ? the structural resistance, under conditions of use and therefore in the second condition, of the tank 1 is required. The waterproofing layer 7 ? preferably in polymeric material, which gives both characteristics of impermeability? that of deformability? plastic. For example, in a preferred embodiment the waterproofing layer 7 can be in a heat sealable polymer. The heat-sealable polymer can? be selected based on the properties? mechanical deformability?/flexibility? and resistance necessary for the application; the realization of this layer in heat-sealable polymer pu? provide for the thermal welding of two or more? end? of a heat-sealable polymer sheet or film. The compatibility? chemistry of the polymer used for the waterproofing layer 7 with the propellant ? preferable to avoid the addition of a further layer to be applied on the internal surface of the waterproofing layer 7. It is useful to indicate that polymers such as PTFE and polyfluorinated products in general tend to have the most? wide range of compatibility? and can therefore be used. In the event that tank 1 is intended to contain cryogenic propellant, ? appropriate to provide that the waterproof material in which the waterproofing layer 7 ? made has a glass transition temperature pi? low cryogenic propellant temperature; There? ? necessary to avoid the phenomenon of cryogenic weakening of the tank 1. As regards the thickness T7 of the waterproofing layer 7, it can? be extremely small, for example between 10 micrometres and 1000 micrometres; it can be suitably selected in relation to the loads and the operating range and according to the dimensions of the tank 1 and the envisaged operating environment.

We now proceed to describe the main layer 6 in detail. The main layer 6 can? have a T6 thickness between 15 and 4500 micrometres. The main layer 6 provides for a plurality of bands 6a, which are mutually engaged to form the cladding 4. In particular, adjacent bands 6a are mutually engaged; in this regard, see figure 3 and figure 4B. Each 6a band can? present a thickness between 7.5 and 2250 micrometres. Do the 6a bands develop longitudinally parallel to the prevailing direction of development D? and parallel to each other. As shown for example in figure 4A, the bands 6a are substantially strips of material. The bands 6a can have the same dimensions, for example the same width and the same length. Alternatively, one or more bands 6a can have at least one dimension, for example at least the width, which is different from each other. Each band 6a has an elongated shape which develops along its own prevailing direction of development and has longitudinal portions defined along this direction and transversal portions defined transversally with respect to this direction. Schematizing each band 6a as a parallelepiped with a rectangular base, the longitudinal portions develop along the long sides of the basic rectangle, while the transversal portions develop along the short sides of the basic rectangle.

The main layer 6 preferably comprises a single fabric layer. The bands 6a of the main fabric layer 6 can be arranged in partial overlap. As shown in figure 3 which illustrates an overlapping area between bands 6a, in correspondence with the overlapping areas between the bands 6a there are not two different and overlapping layers of material but there are two bands of fabric 6a of the same material partially overlapping. Essentially, the main fabric layer 6 presents, proceeding circumferentially along the cladding 4, an alternation between overlapping zones in which portions of adjacent bands 6a are overlapped and non-overlapping zones in which there is simply a 6a band. In correspondence with the overlapping areas, the main layer 6 can present a thickness T6 that ? twice as thick as it has in correspondence with the areas in which the bands 6a are not superimposed; in this regard, see figure 3 in which the thickness T6 of the main layer 6 ? indicated with reference to an overlapping area. In other words, the bands 6a are at least partially superimposed on each other, so that the cladding 4 is formed by a circumferential succession of bands 6a partially superimposed on each other (see figure 4B). In order to obtain the overall cylindrical shape of the shell 4 and therefore of the containment body 2, each band 6a is at least partially curved. Basically, schematizing the cylindrical shell 4 in a flat section (section parallel to the base of the cylinder) as a circumference, each band 6a ? curved in such a way as to define an arc of circumference of the skirt 4. As shown in the accompanying figures, pairs of adjacent bands 6a are engaged with each other; in particular, pairs of adjacent bands 6a are partially superimposed at the respective longitudinal portions. Figure 3 shows a top view, in section, of a portion of the shell 4 in which ? its stratified structure is visible; the main layer 6 of the shell 4 has a first and a second band 6a adjacent to each other, the longitudinal portions of which partially overlap each other. To simplify the graphical representation, the curved trend of the bands 6a is not? illustrated in figure 3.

Adjacent 6a bands may be superimposed according to a given overlapping pattern. The overlay pattern can be recurrent, in particular recurring along the circumferential development of the cladding 4. Possible overlapping patterns between adjacent bands 6a are briefly described below. An example of overlapping scheme provides that a band 6a has both longitudinal portions arranged internally with respect to the adjacent bands (ie both longitudinal portions of a band are arranged ?below? the adjacent bands); this pattern of overlap can? be defined as a continuous overlapping pattern. Another example of overlapping scheme provides that a band 6a has a longitudinal portion arranged internally with respect to a first adjacent band and the opposite longitudinal portion arranged externally with respect to a second adjacent band opposite with respect to the first adjacent band (i.e. a longitudinal portion of a band is arranged "below" a longitudinal portion of the first adjacent band and the other longitudinal portion of the same band is arranged "above" a longitudinal portion of the second adjacent band); this pattern of overlap can? be defined as an alternating overlapping pattern. Clearly, further overlapping patterns between adjacent bands 6a may be envisaged. The overlapping of the bands 6a allows a uniform distribution of the pressure loads over the entire surface of the shell 4 of the tank 1, as well as of other mechanical stresses.

In order to be able to engage adjacent overlapping bands 6a with each other, the tank 1 comprises a joining system. The joining system described here advantageously makes it possible to eliminate the use of seams in the main layer 6 (as will be seen below, the main layer 6 is made of fabric) and other techniques lacking in reliability and repeatability? necessary, as well as decrease the mass to parity? of mechanical resistance. In essence, the joining system ? seamless; There? allows the shell 4 and the containment body 2 to be made without resorting to the use of stitching. Making a shell 4 and a containment body 2 without seams, and in particular with a robust jointing system such as the one described here, increases the sturdiness, reliability and and improves the performance of the containment body 2 and therefore of the tank 1.

In more detail, the joining system can? understand a plurality of junction devices 8 of the mechanical type distributed in correspondence with a plurality? of junction points of the containment body 2. Provide for a plurality? of junction devices 8 suitably distributed, for example as described below, allows the distribution of voltages acting under operating conditions on the shell 4 to be managed in an optimal way. As shown in the attached figures, the junction points are located in the shell 4 and , being configured to join the bands 6a of the cladding 4 together, they are substantially junction points of the cladding 4. Basically, each junction device 8 can? be located at a respective junction point to locally engage the overlapping portions of adjacent bands 6a with each other. Each junction device 8 engages bands 6a with each other by crossing the bands 6a themselves. In accordance with the embodiments illustrated in the attached figures, mechanical type junction devices 8 have been provided. Figures 4A to 5B illustrate a possible distribution of the junction devices 8 which, in the condition of the tanks 1 with expanded volume illustrated in figures 4B and 5B, show that the junction devices 8 can be aligned with each other; in greater detail, figures 4B and 5B show two groups of junction devices 8 in which the junction devices 8 of each group are vertically aligned with each other. In particular, in order to optimize and stabilize the engagement between bands 6a pu? a group of jointing devices 8 aligned with each other for each pair of superimposed fabric bands 6a (see Figure 4B) is provided; the alignment? defined along the overlap direction between bands 6a. Clearly, can be expected a plurality? of groups of junction devices 8 in a number of groups greater than two and/or a different alignment or, more? in general, a different arrangement of the junction devices 8 of the same group. The number of junction devices 8 ? variable, passing from one to innumerable; the number of junction devices 8 ? preferably in the greatest possible number, while reducing its diameter within the limits of availability? and workability? of the elements. The junction devices 8 act as elements for distributing the lateral tension acting on the shell 4; consequently, the more the splicing devices 8 are small in size and distributed over the length of the cladding 4, the lower are the loads acting on the individual bands 6a and on the individual fibres.

As illustrated in the attached figures, the junction devices 8 can protrude externally with respect to the shell 4. In the light of this? and the fact that each junction device 8 can? be in a material different from the materials of the cladding 4 and in particular of the bands 6a (possible materials of the bands are detailed below), and can? then present a conductivity? thermal different from the mantle 4, the tank 1 can? predict a plurality? of roofing elements each of which ? a respective joining device 8 is arranged; are the covering elements configured to act as thermal insulation of the respective junction devices 8, so to optimize the thermal insulation of the shell 4 and therefore of the tank 1.

Each joining device 8 comprises a constraining element 8a capable of constraining overlapping portions of adjacent bands 6a to one another. In order to engage the overlapping portions of adjacent bands 6a, the constraint element 8a can transversely cross the bands 6a that engages and pu? protrude externally with respect to the shell 4. According to a possible embodiment, each constraint and junction element can? consist of a rivet 8, 8a. As illustrated in figures 1, 2 and 3, each rivet 8a crosses the longitudinal portions of adjacent bands in order to be able to engage adjacent bands together. Each rivet 8a has a first and a second end? opposing and a stem arranged between the ends?; at each end? ? defined a rivet head 8a. Stem and heads of each rivet 8a preferably have a circular shape. The stem? at least as long as the sum of the thicknesses of the superimposed portions of the bands 6a so that it can pass through both the superimposed bands 6a in order to be able to engage them together; the first and second heads of each rivet 8a are arranged in abutment with a respective inner and outer surface of the main layer 6a (see figure 3). In embodiments in which the adjacent bands 6a have the same thickness, the shaft of each rivet 8a can be at least twice as long as the thickness of a band 6a. Is the thickness of each constraint element 8a, in particular of each rivet, ? then selected on the basis of the thickness T6 of the main layer 6, while its diameter on the basis of the pressure and mechanical loads acting on the tank 1 and the total number of constraint elements 8. It should be noted that thicknesses of at least 20 micrometres, up to to a maximum of 5000 micrometres, from 1 mm in diameter up to several cm, with preferably circular section. In terms of materials, each constraint element, in particular each rivet 8, 8a, can be in metal material or alloy, from aluminum (7075, 6061, 2024 T6, etc.) to steel (2800 Maraging, 316 stainless, etc.) up to titanium, etc. The very high tensile modulus of these materials or other it still proves necessary given the focus of the load.

It is understood that in alternative embodiments, alternative joining devices 8 of the mechanical type can be provided.

The bands 6a cover the entire lateral surface of the tank 1. The bands 6a can be of any number; more there are numerous bands 6a, many more? junction devices 8 sar? necessary to predict, the greater sar? the weight of the tank 1. However, a symmetrical distribution with pi? of two bands, preferably three or four, proves to be favorable for counteracting mass distribution asymmetries.

According to the invention, the main layer 6 is in fabric. In greater detail, each band 6a which forms the main layer 6? in fabric. Each fabric band 6a comprises fibres, in particular continuous fibres; There? allows for optimal load distribution. The fibers can be engaged with each other in various ways; preferably, the fibers are intertwined. The fibers can be intertwined along at least two transverse or perpendicular directions. The fibers are intertwined in such a way as to optimize the characteristics of structural resistance and distribution of the tensions acting, under operating conditions, on the containment body 2 of the tank 1.

The Applicant has noted that the use of commercial fabrics or fibers currently makes it possible to greatly reduce production times and costs. The continuous nature of the fibers is important, using production methods which allow to maintain a continuous fiber from one interface device 5 to the next.

Expect continuous fibers between interface devices 5, 5? allows you to distribute the load homogeneously longitudinally. This ? due to the very high tensile modulus of the fibers (typically between 1000 and 5000 MPa), much higher than the 30-40 MPa of the polymers making up the waterproofing layer.

Examples of fibers that can be used for this purpose are Zylon, carbon, aramid, glassy, basaltic, etc. fibers. The choice of the best fiber to use depends on the flight conditions to which they are subjected during the flight of the vehicle 100 in which the tank 1 ? integrated. The use of materials resistant to high operating temperatures and insulators such as fiberglass can offer relevant thermal protection in case of need. According to possible embodiments, the fabric can be a mesh in steel, aluminum or other metal alloys, provided? the arrangement allows to maintain the same properties? of deformability? necessary.

The main layer 6 has an internal surface and an external surface, which are defined in correspondence with the fabric bands 6a. As mentioned, in direct contact with the internal surface ? the waterproofing layer 7 is engaged. The waterproofing layer 7 in turn has an internal surface and an external surface; the latter ? engaged in direct contact with the internal surface of the main layer 6. Further layers are described below which can be provided and which can be in contact with the external surface of the main layer 6 or with the internal surface of the waterproofing layer 7.

The layered structure can then understand one or more? further layers.

The layered structure can optionally comprising a thermal insulation layer configured to thermally insulate, under conditions of use, the propellant contained in tank 1. The thermal insulation layer ? an additional layer used to reduce convective and/or conductive heat transfer phenomena. The thermal insulation layer? disposed externally with respect to the main layer 6; in particular, the layer of thermal insulation ? engaged in direct contact with the outer surface of the main layer 6. The thermal insulation layer is not? strictly necessary; the need? to predict it? function of the mission requirements of the vehicle 100 on which ? mounted the tank. An example of an excellent thermal insulation layer for the purpose? represented by ceramic-based paint, comprising micrometric/nanometric spherules of silicon dioxide (silica) or aluminum trioxide (alumina). The paint ? capable of withstanding very high temperatures, in particular higher than 500 K and the spherules are at least one order of magnitude higher? smaller than the thickness of the thermal insulation layer. The latter thickness depends on the propellant used and on the environment of use; for example, cryogenic propellants require higher insulation thicknesses, while for tanks used in a launch vehicle the maximum operating temperature of the paint must be higher. An? alternative can? be the use of expanded polymers such as expanded polyurethane or expanded polypropylene, however their compatibility? in space conditions? yet to be verified. In another embodiment, the thermal insulation function can be be carried out by the fabric bands and the thermal insulation layer can? therefore be represented by, and coincide with, fiber bands of the main layer 6.

The layered structure can also optionally comprising an external coating layer configured to act as a thermal interface between an external environment arranged outside the tank 1 and the tank 1 itself. If foreseen, the external covering layer? the layer more exterior of the layered structure. The outer coating layer can be extremely thin; for example, it can have a thickness of about 20 micrometres. This very thin outer coating layer preferably comprises a reflective paint with a variable emission/absorption ratio. The function of this outer coating layer? that of mediating the radiative exchange of energy with the outside, a function which appears to be of primary importance in space flight. The paint can be organic or inorganic in nature; preferably, given the operating temperatures which can be greater than 500 K, is the paint? inorganic in nature. The emission/absorption ratio? characteristic of each paint and pu? be suitably chosen in order to maintain the system at a given equilibrium temperature once in space. If the thermal insulation layer is also provided, the external coating layer can be engaged in direct contact externally to the thermal insulation layer; in this embodiment, the thermal insulation layer ? disposed between the main layer 6 and the outer coating layer. In the absence of a thermal insulation layer, the outer cladding layer can be in direct contact with the outer surface of the main layer 6.

The layered structure can optionally also include an internal lining layer. The inner lining layer? facing the internal volume of tank 1 and ? configured to come into contact, under operating conditions, with the propellant housed in the tank. The inner lining layer? a compatibility layer?, i.e. a compatible layer, from the point of view of chemical and/or physical interactions, with the propellant with which it is? intended to make contact. The inner lining layer? preferably engaged in direct contact with the internal surface of the waterproofing layer 7. The internal coating layer ? substantially a protective layer provided, if necessary, to protect the waterproofing layer against the potentially active chemical species of the propellants. An example of an internal lining layer involves the use of PTFE to protect the waterproofing layer against hydrogen peroxide or nitric acid/nitrogen tetroxide. The thickness of the inner lining layer? meager; it can be about 20 micrometers. If the waterproofing material or materials of the waterproofing layer 7 are chemically compatible with the propellant, it is not necessary to provide an internal coating layer.

Basically, in its embodiment with a smaller number of layers illustrated in figure 3, the layered structure exclusively comprises the main layer 6 and the waterproofing layer 7; in this embodiment, the main layer 6 is the layer more exterior of the stratified structure and therefore of the shell 4 and the waterproofing layer 7 ? the layer more inside of the stratified structure and therefore of the mantle 4 and ? intended to come into contact with the propellant. As regards the embodiment with a greater number of layers envisaged herein, the layered structure comprises, in the following sequence in a direction which goes from the internal volume of the tank to the environment external to the tank 1: the internal lining layer, the waterproofing 7, the main layer 6, the thermal insulation layer and the outer cladding layer. In this latter embodiment, the outer coating layer is the layer more exterior of the layered structure of the mantle 4 and the inner lining layer ? the layer more interior of the layered structure of the shell 4, intended to come into contact with the propellant. Clearly, further embodiments may be envisaged which provide one or more? further intermediate, inner or outer layers and/or a number of layers different from the number of layers described herein.

As previously anticipated, tank 1 can? further comprise at least one interface device 5 configured to interface the tank 1 to another tank and/or to further components of the spacecraft 100 in which said tank 1 ? intended to be installed. In the embodiment illustrated for example in figure 1, the tank 1 has two interface devices 5, 5?, each of which ? arranged at a respective end? 4a, 4b open of cloak 4 and ? action to close the? extremity? 4a, 4b open to which ? engaged; such interface devices 5, 5? are part of the containment body and contribute to delimiting the internal volume of the tank 1. In other words, the tank 1 can? include an interface device 5 able to close the end? 4a open at the bottom of the shell and to act as a bottom or lower cover of the containment body 2 and a further interface device 5? action to close the? extremity? 4b opposite all? Extremity? bottom 4a and to act as a cover for the containment body 2. The interface device 5 which acts as a bottom can? provide step section 3. In essence, each interface device 5, 5? ? substantially a diaphragm able to close a? extremity? 4a, 4b open of the shell 4, helping to delimit the internal volume of the containment body 2. Figure 1 shows that further interface devices can be engaged to the tank 1, which can allow the engagement of the tank 1 to one or more? further tanks or components of a spacecraft 100 in which the tank 1 is integrated; end? of these further interface devices are shown in dotted line below and above with respect to the tank 1.

In terms of materials, the interface devices 5, 5? can they be made of metal, for example in aluminum (such as aluminum 6061 or 7075 T6) or in alloys with more? high tensile modulus of steel, titanium, etc. or composite material. Interface devices 5, 5? they consist of extremely thin plates (diaphragms), indicatively having a thickness of hundreds of micrometres; such thickness? variable depending on the maximum operating pressure and the chosen material.

Each interface device 5, 5? includes a seat configured to house a respective end? 4a, 4b of the shell 4 of the containment body; as illustrated in figure 1, each extremity? 4a, 4b of cloak 4 ? housed in a seat of a respective interface device 5, 5?. In particular, each interface device comprises a first flange 9 and a second flange 10 (double flange) arranged internally with respect to the first flange 9 at a determined distance from it. The first and second flanges 9, 10 have a circumferential development and are concentric with each other. The distance between them defines a? interspace in correspondence of which? defined the seat for the? extremity? 4a, 4b of the shell 4. Interspace and seat can have an annular development. The headquarters, in section, pu? have a substantially "U" shape, in which the short side of the U defines the bottom of the seat, in correspondence with which the? 4a, 4b of the mantle 4 pu? be placed in abutment, and the long sides of the U define the sides of the seat with which lateral portions of the extremity? 4a, 4b of the shell 4 can come into contact (see figures 1 and 2). From a geometric point of view, both flanges 9, 10 of the double concentric flange can be raised by about 1 cm from the bottom of the seat.

In order to engage the interface devices 5, 5? with the shell 4, the tank comprises engagement elements 11. The engagement elements 11 allow coupling between flanges 9, 10 of the interface devices 5, 5? and end? 4a, 4b of the shell 4. Preferably, are the engagement elements 11 movable or removable and can they be removed, for example to allow the interface devices 5, 5 to be uncoupled? from the shell 4. The enclosed figures show that the engagement between interface devices 5, 5? and mantle 4 pu? be made by means of threaded elements 11; in greater detail, the threaded elements 11 can be of the through captive screw type. Interface devices 5, 5? of the attached figures also show that the flanges 9, 10 of each interface device 5, 5? and the respective extremity? 4a, 4b of the skirt 4 can be provided with mutually aligned holes, preferably threaded holes, in correspondence with which the threaded elements 11 are engaged. Each flange 9,1 10 ? preferably drilled at regular intervals; the holes can therefore be equidistant from each other. Clearly, can engagement elements 11 be provided between the flanges and the respective end? 4a, 4b of the cloak 5, 5? alternative to threaded elements.

To ensure the?impermeability? of the containment body 2, pu? be expected sealing material between the ends? 4a, 4b of the shell 4 and respective interface device 5, 5?. In greater detail, each interface device 5, 5? can? provide a sealing material configured to prevent propellant leakage. The sealing material can comprise at least one gasket, for example a solidifiable gasket, preferably chemically compatible with the propellant intended to be housed in the tank 1. Preferably, each interface device 5, 5? can? provide two plastic gaskets, which are preferably made of the same material as the internal coating layer. In the embodiments illustrated in the attached figures, the watertightness of the tank 1 between the shell 4 and each interface device 5, 5? ? guaranteed by the compression exerted by the stud bolts 11.

The tank 1 can? moreover, a pressurization system 12 configured to determine the passage of the containment body from the first condition to the second condition, i.e. to expand the volume of the tank 1. The pressurization system 12 can be provided. be configured to cause the containment body 2 to pass from the first condition to the second condition by introducing fuel into the internal volume. The introduction of fuel into the containment body 2 increases the internal pressure of the tank 1 and therefore allows the stratified structure of the shell 4 to deform plastically to pass from the reduced volume condition (figure 4A) to the expanded volume configuration (figure 4B) in agreement with what has been previously described; the same transition between such conditions at different volume ? shown, with reference to two tanks 1 installed in a space vehicle 100, by the succession of figures 5A and 5B. The reverse transition from the expanded volume condition to the reduced volume condition? possible, when the propellant inside the tank 1 ? exhausted, by releasing the internal pressure of tank 1; under its weight, the tank 1 autonomously returns to its reduced volume condition. The pressurization system 12 pu? use a technology by itself? Note; for example, the pressurization system 12 pu? be autogenous or induced autogenous or pressurizing gas, etc.

The tank 1 can? further comprising a propellant distribution line 13 or a portion of a propellant distribution line 13 crossing at least partially the internal volume (see figure 2). The propellant distribution line 13 defines a conduit in which it can flowing propellant. Provide a propellant distribution line 13 crossing the tank 1? advantageous for giving the tank 1 a compact structure when between said tank 1? interposed between a further tank 1 and the driving section of the space vehicle 100 in which the tank 1 ? intended to be integrated; in this way, the propellant distribution line 13 extending through the tank 1 allows fluid communication between the further tank 1 and the driving section. The propellant distribution line 13 passing through the tank 1 has the function of keeping the propellant flowing through it separate from the propellant contained in the tank 1. simple is l?use of the same material of which ? waterproofing layer 7 formed; it can be coated on both sides, internal and external, by a coating for compatibility? chemistry analogous to the previously described inner coating layer. Should the coating layer for the internal face and external face of the propellant distribution line 13 be chosen in such a way as to ensure compatibility? with the propellants with which these faces are intended to come into contact with each other.

The tank 1 can? also include additional components per s? known, such as propellant outflow and loading valves, control sensors suitable for controlling pressure, temperature, propellant level, etc.

Use of the tank

The invention also relates to a use of the previously described tank 1. The use of tank 1 ? designed to contain propellant.

Tank assembly

The invention also relates to a tank assembly 50 comprising two tanks 1 of the type previously described. Figure 2 illustrates a tank assembly 50 comprising first and second tanks 1; the latter ? engaged above the first tank and ? separated from the first tank by a first interface device 5?, to which ? engaged a propellant distribution line 13. In figure 2, the second tank? illustrated only by the? extremity? lower 4a of the mantle 4, which ? committed to the first interface device 5?. Basically, the first interface device 5? it acts as a cover device for the first tank and as a bottom device for the second tank. In addition to the first interface device 5?, ? a second interface device 5 is provided, arranged at the end? bottom 4a of the skirt 4 of the first tank 1, also crossed by the propellant distribution line 13. As illustrated in figure 2, the propellant distribution line 13 can? be committed to each interface device 5, 5? by means of engagement elements 11, such as threaded elements, of the type previously described. The first interface device 5? has a suitable predisposition, for example a portion equipped with an opening (see figure 2), to be able to be crossed by the propellant distribution line 13. By providing the propellant distribution line 13 in the same material as the waterproofing layer 7, the propellant distribution line 13 pu? be in turn plastically deformable so as to be able to deform when the tank 1 assumes the first condition and the second condition. Considering that the tanks 1 of the tank assembly 50 are mutually isobaric, it should be noted that it is not high mechanical strength is required for the propellant distribution line 13.

Both tanks 1 have the same prevailing direction of development D?. As illustrated in figure 2, to allow the outlet of the propellant distribution line 13 from the first tank, the passage section 3 of the first tank 1 can be dislocated laterally with respect to the prevailing direction of development D?; in this regard, compare the arrangement of the passage section of the tank 1 of figure 1 with the arrangement of the passage section 3 of the tank 1 of figure 2.

Spacecraft

The invention also relates to a space vehicle 100 comprising at least one tank of the type previously described. Examples of spacecraft 100 are launchers and interplanetary vehicles.

In more detail, spacecraft 100 can? comprising two tanks 1 according to the invention, i.e. a tank assembly 50 as previously described. In case two or more are foreseen? tanks 1, each tank 1 ? intended to contain a respective propellant.

In greater detail, the space vehicle 100 comprises an elongated box-shaped body extending along a prevalent development direction D?. The box body? defined at least partially by the tank 1 or by the tanks 1. As illustrated in figures 5A and 5B, in the embodiment in which the spacecraft 100 comprises two tanks 1, each tank 1 defines a respective portion of the box-like body. Can the tanks 1 share the same prevailing development direction D?, which preferably coincides with the prevailing development direction of the spacecraft D? (see figure 5B).

The spacecraft 100 further comprises a drive section 101, which is equipped with one or more engines. Preferably, the engines are rocket engines. In order to power the driving section 101 to allow the propulsion of the space vehicle 100, the one or more? tanks 1 are in fluid communication with the driving section 101.

In embodiments in which at least a first and a second tank 1 are provided, in which the first tank ? interposed between the driving section 101 and the second tank, a propellant distribution line 13 can pass through the first tank in order to allow the driving section to be fed with the propellant contained in the second tank in accordance with what has been previously described.

The spacecraft 100, similarly to the tank 1, can? assume a reduced-volume condition (first condition) and an expanded-volume condition (second condition), which represents the operating condition of the spacecraft 100. Do you expect the spacecraft 100 to assume the reduced-volume condition? particularly advantageous in that it allows the vehicle 100 to assume a compacted configuration in which it can? be stored occupying a small volume. When the spacecraft 100 ? in the reduced volume condition each tank 1 of the spacecraft 100 ? in turn in the reduced volume condition (see figure 5A), while when the spacecraft 100 is in the expanded volume condition each tank 1 of the spacecraft 100 ? in turn in the expanded volume condition (see Figure 5B).

The transition between the first and second condition of the 100 spacecraft? carried out by the previously described deformation of each tank 1 of the space vehicle 100. Figures 5A and 5B illustrate a space vehicle, equipped with two tanks according to the invention, respectively in the first condition and in the second condition.

Method of manufacturing a tank

The present invention also relates to a method of manufacturing a tank 1 of the type previously described. The method comprises the steps of arranging fabric bands 6a to form a fabric layer 6 (the main layer) of a shell 4 of a containment body 2 of a tank 1. This step involves engaging adjacent fabric bands 6a together , preferably by means of the joining devices 8 of the joining system described above. In greater detail, the engagement of bands 6a in adjacent tissue ? carried out by overlapping longitudinal portions of bands 6a in adjacent fabric.

The method further provides for providing a waterproofing layer 7 of the type previously described and for engaging the waterproofing layer 7 to the fabric layer 6 so that the waterproofing layer 7 is internal with respect to the main fabric layer 6; in this way the stratified structure of the shell 4 is formed. The preparation or the engagement of the waterproofing layer 7 can? provide for the thermal welding of two or more? end? of a heat-sealable polymer sheet or film.

In accordance with what has been previously described, the method can furthermore provide for the engagement, to the main layer 6 or to the waterproofing layer 7 of the stratified structure of the shell 4, of one or more? between: an inner lining layer, an outer lining layer and a thermal insulation layer. These layers make it possible to complete the layered structure if necessary. The number of layers? chosen and modulated on the basis of various factors, such as the environment or field of use in which it is? destined to operate the space vehicle 100 in which the tank 1 will come? integrated.

The method also provides for engaging an interface device 5, 5? at each end? 4a, 4b open of the shell 4 in accordance with what has been previously described. This phase allows to form the containment body 2 and can envisage, in particular, to engage respective interface devices 5, 5? at the ends? 4a, 4b opposite each other of the skirt 4 (see figures 1 and 2).

Method of operation of a tank

The present invention also relates to a method of operating a tank 1 of the type previously described. The method provides for setting the tank 1 in the first condition or in the second condition and for determining the transition of the tank 1 from the first condition to the second condition or vice versa.

The transition of tank 1 from the first to the second condition, and vice versa, is possible thanks to the deformation of the layered structure of the mantle 4. The deformation of the layered structure ? preferably an at least partial plastic deformation of the layered structure. In accordance with what has been previously described, the at least partial plastic deformation of the stratified structure provides for the plastic deformation of the waterproofing layer 7 of the stratified structure.

The transition of the tank 1 from the first condition with reduced volume to the second condition with expanded volume ? preferably carried out by means of the pressurization system 12 in accordance with what has been previously described.

The transition of tank 1 from the first condition with reduced volume to the second condition with expanded volume allows tank 1 to be prepared for use, while the reverse transition allows tank 1 to be stored in a reduced volume.

Method of operation of a spacecraft

The present invention further relates to a method of operation of a spacecraft 100 of the type described above. The method provides for setting a spacecraft 100 in the first condition or in the second condition and determining the transition of the spacecraft 100 from the first condition to the second condition or vice versa.

The transition of spacecraft 100 from the first to the second condition, or vice versa, ? possible thanks to the transition of each tank 1 of the vehicle 100 from the first to the second condition, or vice versa.

The transition of the spacecraft 100 from the first reduced-volume condition to the second expanded-volume condition allows the spacecraft 100 to be prepared for use, while the reverse transition allows the spacecraft 100 to be stored in a reduced volume.

Further advantages of the invention

The tanks 1 according to the invention are distinguished from the traditional tanks in composite material by the absence of a rigid metal container; in fact, the invention makes use of a deformable containment body 2, having the stratified structure previously described. The absence of a rigid metal container, the layered structure of the shell 4 previously described with the relative materials and layers of reduced thickness and the possibility to use an extremely thin ceramic coating reduces the weight of the tank by about 100 times.

Comparing this approach to traditional balloon tanks, the substantial difference is not only ? relating to the weight of the final tank, but also relating to the further thermo-mechanical characteristics. In fact, the technical solution proposed for the tank, in addition to the much greater resistance to punctures and deformations,? much more stable at high temperatures due to the materials used, while maintaining the same structural strength. With regard to the weight, it should be noted that the tank 1 according to the invention can be 12 to 15 times less than the weight of a traditional balloon tank.

The invention makes possible the realization of a tank 1 capable of being folded on itself; There? allows you to make more efficient logistics.

The invention makes it possible to produce a tank 1, the shell 4 of which has a main layer 6 of fabric, without seams in the vicinity of the tank. of the junctions between bands 6a of fabric; There? allows you to avoid strong critical points? given the unreliability? and repeatability? of the sewing process.

The tank 1 according to the invention, providing a weighted combination of metal junction devices 8 and bands of fibers 6a, allows to distribute the loads evenly with a single layer of fibers (the main layer 6 of the layered structure), achieving clear improvements on the final weight of the tank and therefore of the space vehicle 100. With regard to the homogeneous distribution of the load, it is necessary to indicate that in the tank 1 the load ? distributed longitudinally by the fibers themselves of the main layer 6, connected via removable engagement elements 11 to the interface devices 5, 5? rigid connected to the spacecraft 100. The latitudinal, or circumferential, load? instead transmitted uniformly to the fibers of the main layer 6 through the junction devices 8 preferably made of alloys with a very high tensile modulus.

Furthermore, the tanks 1 according to the invention provide a containment body 2 equipped with an excellent meeting point between deformability? and resistance of the tank 1 thanks to the provision of a stratified structure in which the deformability? plastic ? entrusted to the waterproofing layer 7, while the other layers, in particular the main layer 6 in fabric but also the other optional layers, can follow the deformation, flexing, thanks to their very reduced thickness.

Additional layers such as the thermal insulation layer which includes micrometric / nanometric ceramic particles also offer a conductivity? thermal comparable to other insulators but maximum operating temperatures 10-15 times higher. The present invention ? in fact, it has been optimized with respect to all existing technologies for the least possible mass expenditure for applications with large delta-v requirements (i.e. of impulsive speed variation), such as launchers or interplanetary vehicles 100.

The tanks 1 according to the invention can be adapted, by suitably preparing the layers of the stratified structure, and therefore used to contain any type of propellant, from cryogenic propellants (oxygen, hydrogen, methane, etc.), to storable propellants (peroxide of hydrogen, kerosene, alcohol, hydrazine, nitrogen tetroxide, etc.) up to pressurizing gases (helium, nitrogen).

The construction of the tanks 1 based on the use of flexible polymers, alloys and/or ultra-resistant fibers not only allows for much greater ease of construction and a drastically lower cost than the tanks of the prior art, but also numerous further advantages.

The tanks 1 according to the invention are in fact foldable, allowing the space vehicle 100 which integrates them to occupy a negligible volume when empty (volume of the vehicle 100 when the tanks 1 are without propellant; see figure 5A) with respect to the final volume (volume of the vehicle 100 under conditions of use; see figure 5B), even a thousand times smaller than the final volume.

The tanks 1 and the vehicles 100 according to the invention are also much more? resistant to shocks that can occur during handling, making it much more? easy transport and logistics of the same. The ratio between the dry mass (ie in the condition in which the vehicle 100 houses neither propellant nor payload) and fully loaded (condition in which the propellants are housed in the tanks 1) ? the most higher than any other solution currently available, making the technology potentially gravimetrically and volumetrically more efficient for carrying propellant in spaceflight.

Finally, the space vehicles 100 according to the invention are also capable of withstanding the thermal regimes of re-entry, thus allowing reusability within the spacecraft. of the spacecraft, in particular also of 100 miniaturized launchers.

Claims (20)

Claims 1. Tank (1) for a space vehicle (100), the tank (1) developing along a prevailing direction of development (D?) and presenting a containment body (2) adapted to contain propellant, the containment body (2 ) defining an internal volume and comprising a shell (4) having a layered structure, the layered structure (4) providing at least: - a main layer (6), the main layer (6) being made of fabric, - a waterproofing layer (7) arranged internally with respect to the main layer (6), characterized by the fact that the internal volume? variable and the containment body (2) ? configured to assume at least a first condition having a first internal volume and a second condition having a second internal volume different from the first internal volume, by the fact that the main layer (6) comprises a plurality? of fabric bands (6a), and by the fact that the tank (1) further comprises a joining system configured to bind fabric bands (6a) together. The tank according to claim 1, the layered structure having a single fabric layer and the waterproofing layer (7) being in direct contact with the main layer (6). 3. Tank according to claim 1 or 2, the layered structure being at least partially plastically deformable, the containing body (2) being configured to pass between the first condition and the second condition by at least partial plastic deformation of the shell (4). 4. Tank according to claim 1 or 2 or 3, wherein the waterproofing layer (7) is plastically deformable, preferably the waterproofing layer (7) being made of plastic and/or polymeric material. 5. Tank according to any one of the preceding claims, wherein adjacent bands (6a) are at least partially superimposed on each other according to a given recurring pattern along the circumferential development of the shell (4). 6. Tank according to any one of the preceding claims, wherein the bands (6a) develop longitudinally along, preferably parallel to, said main direction of development (D?). 7. Tank according to any one of the preceding claims, wherein each fabric band (6a) comprises fibers intertwined along two or more? directions. 8. A tank according to any one of the preceding claims, wherein the layered structure is configured to allow the passage of the containment body (2) from the first condition to the second condition, and vice versa, a plurality? of times. 9. Tank according to any one of the preceding claims, wherein the joining system is configured to bind together bands (6a) in adjacent fabric, the joining system comprising a plurality of of junction devices (8) of the mechanical type distributed at a plurality? of junction points of the containment body (2), 10. Tank according to claim 9, each junction device (8) being configured to constrain portions of adjacent bands (6a) to each other, said portions being located at the point where the junction device (8) is located. dislocated. 11. Tank according to any one of the preceding claims, wherein the joining system is seamless. 12. Tank according to any one of the preceding claims, wherein the stratified structure has a thickness of between 10 and 7,500 micrometres, in particular between 20 and 5,000 micrometres. The tank according to any one of the preceding claims, wherein the layered structure comprises a thermal insulation layer configured to thermally insulate the tank under conditions of use, the thermal insulation layer being external to the main layer (6). 14. Tank according to any one of the preceding claims, wherein the stratified structure further comprises an internal lining layer facing the internal volume (1) and configured to come into contact, under operating conditions, with the propellant housed in the tank (1). The tank according to any one of the preceding claims, further comprising at least one interface device (5, 5?) configured to interface the tank (1) to another tank (1) and/or to further components of the spacecraft (100) in which said tank (1) ? intended to be installed. 16. Tank according to claim 15, wherein the shell (4) develops along said prevailing direction of development (D?) between a first and a second end? opposing (4a, 4b), at least one of these ends? (4a, 4b) being open, said at least one interface device (5, 5?) being arranged at said at least one end? open and closing said extremity? open (4a, 4b), optionally both the first and the second end? (4a, 4b) of the shell (4) are open, the tank (1) comprising a first and a second interface device (5, 5?) configured to cover the first and second ends respectively? (4a, 4b). 17. Tank according to any one of the preceding claims, further comprising a propellant distribution line (13) or a portion of a propellant distribution line (13) crossing at least partially said internal volume, the propellant distribution line (13) defining a duct in which pu? flowing propellant. 18. Tank according to any one of the preceding claims, further comprising a pressurization system (12) configured to determine the passage of the containment body (2) from the first condition to the second condition, optionally the pressurization system (12) being configured to determine the passage of the containing body from the first condition to the second condition by introducing fuel into said internal volume. 19. Space vehicle (100) comprising: - an elongated box-shaped body developing along a prevailing direction of development (D?), - at least one tank (1) according to any one of claims 1 to 18, the tank (1) being configured to contain propellant, said at least one tank (1) at least partially defining the box-like body, optionally the vehicle comprising a first and a second tank (1), each tank (1) being in accordance with any one of claims 1 to 18 and defining a respective portion box-shaped. 20. Method of operation of a tank (1) comprising at least the following steps: - providing at least one tank (1) according to any one of claims 1 to 18, the tank (1) being in the first condition or in the second condition, - determining the transition of said at least one tank (1) from the first condition to the second condition or vice versa.