Cryogenic fluid storage unit

Abstract

The invention provides a storage unit (1) comprising an inner reservoir (3) delimiting inwardly a cryogenic fluid storage volume (5), an outer reservoir (7) containing the inner reservoir (3), and a suspension (9) attaching the inner reservoir (3) to the outer reservoir (7), the suspension (9) comprising a connection (23, 25) comprising: an outer tube (27) comprising an inner tube (27) and an outer tube (27); an outer tube having an outer proximal end (29) attached to the inner reservoir (3) and an outer distal end (31) located inside the storage volume (5); -a base plate (33) closing the outer distal end (31); -an inner tube (41) arranged inside the outer tube (27), the inner tube having an inner proximal end (43) connected to the outer reservoir (7) and an inner distal end (45) attached to the inner reservoir (3); -a movement limiter (81) limiting the deflection of the inner tube (41) relative to the inner reservoir (3) in a plane perpendicular to the central axis (C) of the inner tube (41).

Description

Technical Field

[0001] The present invention generally relates to a cryogenic fluid storage unit. Background Art

[0002] Such a storage unit may include an inner reservoir internally defining a cryogenic fluid storage volume, an outer reservoir housing the inner reservoir, and a suspension attaching the inner reservoir to the outer reservoir.

[0003] In order to limit convective heat transfer from the outer reservoir to the inner reservoir, the space between the inner reservoir and the outer reservoir is typically maintained under a high vacuum.

[0004] Radiation transfer is limited by placing a layer of insulating material over the inner reservoir.

[0005] Heat conduction from the outer reservoir to the inner reservoir occurs primarily via the suspension.

[0006] It can be relatively high.

[0007] In this context, the present invention aims to propose a storage unit whose suspension is designed to minimize the heat flow circulating by conduction from the external reservoir to the internal reservoir. Summary of the invention

[0008] To this end, a first embodiment of the present invention is directed to a cryogenic fluid storage unit comprising an inner reservoir inwardly defining a cryogenic fluid storage volume, an outer reservoir accommodating the inner reservoir, and a suspension attaching the inner reservoir to the outer reservoir, the suspension comprising a connection member comprising:

[0009] - an outer tube having an outer proximal end attached to the inner reservoir and an outer distal end located inside the storage volume;

[0010] - a bottom plate closing the distal outer end;

[0011] - an inner tube arranged inside the outer tube, the inner tube having an inner proximal end directly attached to the rigid member and having an inner distal end attached to the internal reservoir, the rigid member being connected to the external reservoir;

[0012] - a motion limiter that limits deflection of the inner tube relative to the internal reservoir in a plane perpendicular to the central axis of the inner tube, the motion limiter:

[0013] attached to the rigid member and / or the inner proximal end;

[0014] Or attached to the internal reservoir and engaged with the rigid member and / or the inner proximal end.

[0015] The inner tube is designed to withstand only the usual mechanical stresses associated with normal storage use. When the storage unit is mounted on a motor vehicle, these stresses are generated by vibrations generated, for example, during emergency braking, sharp turns or when the vehicle is driven on rough roads.

[0016] Conversely, if the storage unit is subjected to abnormal stresses, such as an unexpected impact, the motion limiter limits the deflection of the inner tube in a plane perpendicular to the central axis of the inner tube.

[0017] This limits the deformation of the inner tube, preventing it from entering the plastic range and thus undergoing irreversible deformation.

[0018] Without a motion restrictor, the potential for damage to the inner tube under abnormal stress conditions would be significant.

[0019] The motion limiter is attached or joined to an element having greater rigidity than the central portion of the inner tube, so that the mechanical resistance is lower. The element is a rigid member by which the inner tube is attached to the external reservoir and / or the inner proximal end. The inner proximal end has better mechanical resistance than the central portion of the inner tube due to the fact that it is directly attached to the rigid member.

[0020] The movement limiter thus makes it possible to choose a reduced wall thickness for the inner tube, just enough to withstand the usual mechanical stresses. This helps to limit the conduction of heat from the outer reservoir to the inner reservoir.

[0021] The fluid storage unit may also include one or more of the following features, considered alone or in any technically possible combination:

[0022] - the inner reservoir has an aperture through which the inner tube is connected to the outer reservoir, the motion limiter engaging the aperture to limit deflection of the inner tube;

[0023] -The storage unit comprises:

[0024] - a valve block having at least one internal passage for a cryogenic fluid;

[0025] * at least one circulation pipe extending inside the inner pipe and fluidly connecting the at least one internal channel to the storage volume;

[0026] The rigid component is the valve block;

[0027] - the motion limiter has a specific axial length and is engaged in the orifice over a length less than 50% of said specific length;

[0028] - the movement limiter is a sleeve arranged around the valve block and / or the inner proximal end;

[0029] - the connector comprises a first cup having a first central portion rigidly attached directly to the valve group and / or the inner proximal end, and a first edge rigidly attached to the external reservoir, the movement limiter comprising a cylindrical portion arranged around the valve group and / or the inner proximal end and rigidly attached thereto, the movement limiter further comprising a protruding flange rigidly attached to the first cup;

[0030] -The motion restrictor is a ring attached to the internal reservoir;

[0031] According to another embodiment constituting a variation of the first embodiment, the invention relates to a cryogenic fluid storage unit comprising an inner reservoir delimiting inwardly a cryogenic fluid storage volume, an outer reservoir accommodating the inner reservoir, and a suspension attaching the inner reservoir to the outer reservoir, the suspension comprising a connection comprising:

[0032] - an outer tube having an outer proximal end attached to the inner reservoir and an outer distal end located inside the storage volume;

[0033] - a bottom plate closing the outer distal end;

[0034] - an inner tube arranged inside the outer tube, the inner tube having an inner proximal end connected to the outer reservoir and an inner distal end attached to the inner reservoir;

[0035] - a second cup having a second central portion and a second edge rigidly attached to the outer reservoir;

[0036] - a sliding tube passing through the second aperture in the second central part and rigidly attached to the second central part, the inner proximal end being slidably engaged in the sliding tube;

[0037] - a motion limiter that limits deflection of the inner tube relative to the internal reservoir in a plane perpendicular to the central axis of the inner tube, the motion limiter:

[0038] attached to a slide tube;

[0039] Or attached to the internal reservoir and engaged with the sliding tube.

[0040] Furthermore, the storage unit may be such that the sliding tube extends perpendicularly to the central axis relative to the motion limiter.

[0041] According to both embodiments, the connection may advantageously comprise a plurality of tubes coaxial to one another and arranged inside one another, the inner tube belonging to the plurality of tubes and being the innermost tube of the plurality of tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Other characteristics and advantages of the invention will become apparent from the following detailed description given by way of non-limiting illustration with reference to the accompanying drawings, in which:

[0043] -[ Figure 1 ] Figure 1 is an axial cross-sectional view of a cryogenic fluid storage unit;

[0044] -[ Figure 2 ] Figure 2 According to the first embodiment Figure 1 an enlarged axial cross-sectional view of a portion of a storage unit suspension;

[0045] -[ Figure 3 ] Figure 3 is similar to Figure 2 , showing a variation of the first embodiment,

[0046] -[ Figure 4 ] Figure 4 is similar to Figure 2 , showing a second embodiment that does not provide for connection of cryogenic fluid conduit passages; and

[0047] -[ Figure 5 ] Figure 5 yes Figure 4 Detail of V. DETAILED DESCRIPTION

[0048] exist Figures 2 to 5 In the drawings, some of the welds connecting the parts to each other are not shown.

[0049] Figure 1 The storage unit 1 shown is used for storing a cryogenic fluid.

[0050] A cryogenic fluid is understood to mean a fluid at a very low temperature which can be at least partially in liquid form within the storage unit.

[0051] This fluid is typically hydrogen. Alternatively, the fluid is helium, nitrogen, a natural gas such as methane CH4, air or any other suitable fluid.

[0052] The storage unit is typically arranged to be mounted on a vehicle having an electric propulsion motor, such as a motor vehicle, a train, a boat or any other vehicle.

[0053] Motor vehicles are, for example, cars, utility vehicles, trucks, and the like.

[0054] The storage unit 1 is designed to power a fuel cell. The fuel cell is configured to generate electricity and to power an electric propulsion motor of the vehicle.

[0055] The cryogenic fluid storage unit 1 comprises an inner reservoir 3 inwardly delimiting a cryogenic fluid storage volume 5 , an outer reservoir 7 accommodating the inner reservoir 3 , and a suspension 9 attaching the inner reservoir 3 to the outer reservoir 7 .

[0056] In the example shown, the internal reservoir 3 has a horizontal centre axis C.

[0057] The internal reservoir 3 comprises an outer casing 11 which is closed at both axial ends by a bottom 13 .

[0058] The housing 11 is cylindrical with the central axis C as its center.

[0059] The external reservoir 7 also generally has a horizontal axis.

[0060] It comprises a housing 15 which is closed at both axial ends by a bottom 17 .

[0061] The housing 15 is cylindrical with the central axis C as its center.

[0062] The inner reservoir 3 and the outer reservoir 7 define between them an intermediate space 19 which is kept under a high vacuum.

[0063] This vacuum is typically of the order of 10 −5 mbar in order to strongly restrict the convective heat transfer from the outer reservoir 7 to the inner reservoir 3 .

[0064] The thermal insulator 21 is interposed between the inner reservoir 3 and the outer reservoir 7. The thermal insulator 21 is generally placed on the outer surface of the inner reservoir 3. The thermal insulator 21 includes, for example, a plurality of metal plates stacked on each other with fiber layers interposed therebetween.

[0065] The suspension 9 is arranged such that the entire weight of the inner reservoir 3 is borne by the outer reservoir 7 via the suspension 9 .

[0066] The weight of the internal reservoir 3 is understood here to include the weight of the cryogenic fluid stored in the internal reservoir 3 .

[0067] The accelerations to which the internal reservoir 3 and the cryogenic fluid contained therein are subjected are also transmitted to the external reservoir 7 via the suspension 9 .

[0068] When the storage unit 1 is installed in a vehicle, these accelerations are caused by changes in the direction of the vehicle, braking or acceleration of the vehicle, unevenness or irregularities of the road, or impacts to the vehicle.

[0069] In the example shown, the suspension 9 comprises two connecting elements 23 , 25 .

[0070] The connecting pieces 23 , 25 each suspend one of the two opposite axial ends of the inner reservoir 3 from the outer reservoir 7 .

[0071] The connecting members 23 and 25 are different from each other.

[0072] The connection 23 is designed to allow the cryogenic fluid to flow into the storage volume 5 , or to flow out of the storage volume 5 .

[0073] In contrast, the connection 25 is not designed for the passage of cryogenic fluids.

[0074] like Figure 2 As shown in , the connecting member 23 includes:

[0075] an outer tube 27 having an outer proximal end 29 attached to the internal reservoir 3 and an outer distal end 31 located inside the storage volume 5;

[0076] - a bottom plate 33 which closes the outer distal end 31;

[0077] An inner tube 41 arranged inside the outer tube 31 , having an inner proximal end 43 directly attached to a rigid member connected to the external reservoir 7 , and an inner distal end 45 attached to the internal reservoir 3 .

[0078] The connecting member 23 also includes:

[0079] an intermediate tube 35 arranged inside the outer tube 27 , having an intermediate proximal end 37 and an intermediate distal end 39 attached to the internal reservoir 3 ; and

[0080] An annular ring 47 connecting the intermediate distal end 39 to the inner distal end 45 .

[0081] Thus, the inner distal end 45 is attached to the inner reservoir 3 via the annular ring 47 and the intermediate tube 35 .

[0082] The outer tube 27 is substantially cylindrical and coaxial with the central axis C.

[0083] It is located within the storage volume 5 , typically completely within the storage volume 5 .

[0084] An opening 49 is provided in the bottom 13 of the inner reservoir 3. An inner ring 51 engages in the opening 49 and is rigidly attached to the bottom 13. The outer peripheral edge of the inner ring 51 is tightly welded to the edge of the opening 49.

[0085] On the side facing the storage volume 5 , the inner ring 51 has substantially cylindrical outer ribs 53 .

[0086] The outer rib 53 is coaxial with the central axis C and has substantially the same diameter as the outer proximal end 29 .

[0087] The outer proximal end 29 is tightly welded to the outer rib 53 .

[0088] Similarly, the inner ring 51 has a second substantially cylindrical rib 55 on its side facing the storage volume 5 .

[0089] This second rib 55 is coaxial with the central axis C and has the same diameter as the intermediate proximal end 37 .

[0090] The intermediate proximal end 37 is tightly welded to the second rib 55 .

[0091] The bottom plate 33 seals the outer distal end 31. It has a bottom 57 which is extended by an upright edge 59 tightly welded to the outer distal end 31.

[0092] The bottom 57 is curved towards the interior of the storage volume 5 .

[0093] The annular ring 47 is coaxial with the central axis C.

[0094] It has a U-shaped cross section in a radial plane containing the central axis C. The annular ring 47 thus has an outer cylindrical wall 61 and an inner cylindrical wall 63 which are connected to each other by a base 65 .

[0095] The outer wall 61 has substantially the same diameter as the intermediate distal end 39 and is welded thereto.

[0096] The inner wall 63 has substantially the same diameter as the inner proximal end 45 and is welded to the inner proximal end thereof.

[0097] The intermediate tube 35 has a wall thickness of between 0.5 mm and 2.5 mm, preferably between 0.5 mm and 1.5 mm, for example 1 mm.

[0098] It is made of austenitic stainless steel, for example, at Rp 0.2 of 270 MPa. Typically, it is made of 1.4310 grade or 304 type stainless steel.

[0099] The intermediate proximal end 37 and the intermediate distal end 39 are, for example, surrounded by a sleeve 67 in order to increase the rigidity of the connection with the rib 55 and with the outer wall 61 , respectively.

[0100] Similarly, the inner tube 41 has a wall thickness between 0.5 mm and 2.5 mm, preferably between 0.5 mm and 1.5 mm, for example 1 mm.

[0101] It is made of austenitic stainless steel, for example, at Rp 0.2 of 270 MPa. Typically, it is made of 1.4310 grade or 304 type stainless steel.

[0102] The inner proximal end 43 and the inner distal end 45 are surrounded, for example, by a sleeve 71 in order to increase the rigidity of the connection with the inner wall 63 and with the rigid member, respectively.

[0103] The storage unit comprises a valve block 73 having at least one internal passage 74 for a cryogenic fluid.

[0104] The storage unit 1 further comprises at least one circulation pipe 75 which extends inside the inner pipe 41 and fluidically connects the at least one internal channel 74 to the storage volume 5 .

[0105] Typically, the valve block 73 includes four internal passages 74 connected to four circulation pipes 75 .

[0106] In this case, one of the channels 74 and the corresponding tube 75 are provided for filling the storage volume 5. The other channel 74 and the corresponding tube 75 are provided for emptying the storage volume 5.

[0107] Two further channels 74 and two further corresponding tubes 75 are designed to circulate the cryogenic fluid in a circuit to the heat exchanger.

[0108] The rigid component is advantageously the valve block 73 .

[0109] The valve block is directly attached to the inner proximal end 43 of the inner tube 71 .

[0110] The valve assembly 73 is axially aligned with the inner tube 41 .

[0111] Towards the inner tube 41 , it has a substantially cylindrical end section 76 .

[0112] The end portion 76 is coaxial with the central axis C. It is delimited radially to the outside by an outer surface 77 and axially towards the inner tube 41 by a connecting surface 78 .

[0113] The outer surface 77 is substantially cylindrical, and its cross section perpendicular to the central axis C is substantially the same as the cross section of the inner proximal end 43 .

[0114] The inner proximal end 43 is connected to the outer peripheral edge of the connecting surface 78 .

[0115] The internal reservoir 3 also comprises an orifice 79 through which the internal tube 41 is connected to the external reservoir 7 .

[0116] An orifice 79 is provided in the inner ring 51. The subassembly consisting of the valve block 73 and the inner tube 41 passes through the orifice 79.

[0117] The space defined inside the outer tube 27 is therefore isolated from the storage volume 5 , but communicates with the intermediate space 19 via the orifice 79 .

[0118] Advantageously, the connection 23 comprises a movement limiter 81 which limits the deflection of the inner tube 41 relative to the internal reservoir 3 in a plane perpendicular to the central axis of the inner tube 41 .

[0119] The movement limiter 81 limits the deflection of the inner tube 41 relative to the inner reservoir 3 to a maximum of less than 3 mm.

[0120] In the example shown, the central axis of the inner tube 41 corresponds to the central axis C. The deflection of the inner tube 41 takes place at the inner proximal end 43. It corresponds to a radial displacement of the inner proximal end 43 from its rest position.

[0121] As mentioned above, the maximum value is set at a value less than 3 mm, typically between 1.5 mm and 2.5 mm, for example 2 mm.

[0122] A motion limiter 81 engages the aperture 79 to limit deflection of the inner tube 41 .

[0123] The motion limiter 81 is rigidly attached to the rigid member, ie to the valve block 73 .

[0124] Instead, it is attached at the inner proximal end 43 .

[0125] According to another variant, it is attached both to the rigid member and to the inner tube 41 .

[0126] The movement limiter 81 is a sleeve arranged around the inner proximal end 43. The radial distance between the movement limiter 81 and the inner surface of the aperture 79 thus corresponds to the maximum deflection of the inner tube 41.

[0127] Advantageously, the connecting piece 23 comprises a first cup 83, whose first central portion 84 faces the bottom 13 of the internal reservoir 3 and whose first edge 85 is rigidly attached to the internal surface of the external reservoir 7. It is of the type disclosed, for example, in patent application number FR2211366.

[0128] The first central portion 84 of the cup 83 is oriented substantially perpendicularly to the central axis C. It has a first central orifice 86 through which the valve block 73 passes.

[0129] The motion limiter 81 is advantageously a stepped washer.

[0130] It has a cylindrical portion 87 which is arranged around the valve block 73 and / or the inner proximal end 43. The cylindrical portion 87 is rigidly attached to the valve block 73 and / or the inner proximal end 43. The motion limiter 81 also includes a protruding flange 88 rigidly attached to the first cup 83.

[0131] A protruding flange 88 is arranged around the first central aperture 86 .

[0132] A protruding flange 88 is formed at one end of the cylindrical portion 87 .

[0133] Only the end 89 of the cylindrical portion 87 opposite the protruding flange 88 engages in the orifice 79 of the internal reservoir 3 .

[0134] Thus, if the motion limiter 81 has a given overall axial length, the motion limiter 81 is engaged in the aperture 79 only over a length that is less than 50% of the given overall length.

[0135] This prevents excessive radiative heat transfer between the motion restrictor 81 and the edge of the aperture 79 .

[0136] Each internal channel 74 has at one end a counterbore 93 formed in the connection surface 78. A connection sleeve 95 is rigidly attached in this counterbore 93. One end of the corresponding circulation pipe 75 is rigidly attached to the connection sleeve 95.

[0137] Furthermore, each circulation pipe 75 is connected to the bottom plate 33 and communicates with the storage volume 5 through the bottom plate 33 .

[0138] For this purpose, the bottom plate 33 has an orifice 97 in which other connecting sleeves 99 engage. Each circulation pipe 75 is rigidly and tightly attached to one of the other connecting sleeves 99 .

[0139] Each circulation tube 75 has a wall thickness between 0.1 mm and 0.6 mm, preferably between 0.2 mm and 0.4 mm, for example 0.3 mm. These circulation tubes 75 are usually made of 316L stainless steel.

[0140] In order to compensate for the different expansions between the or each circulation pipe 75 and the outer pipe 27 , the or each circulation pipe 75 comprises at least one thermal expansion compensator 101 .

[0141] In fact, the or each circulation tube 75 may have a much lower temperature than the outer tube 27, especially when the storage volume 5 is first filled. During this first filling operation, the storage volume 5 is at ambient temperature, as is the outer tube 27. In contrast, the circulation tube 75 is at substantially the same temperature as the cryogenic fluid. For a 420 mm circulation tube 75, when the cryogenic fluid is liquid hydrogen at 20 K, the length contraction of the circulation tube 75 may be up to 1.6 mm.

[0142] In the example shown, each circulation pipe 75 has a plurality of thermal expansion compensators 101 distributed along its length.

[0143] For example, it has three thermal expansion compensators 101 evenly spaced along the circulation pipe 75 .

[0144] The or each thermal expansion compensator 101 is advantageously a corrugated section of the circulation pipe 75 .

[0145] Each annular segment includes a plurality of annular areas 103 protruding outward from the circulation pipe 75, each of which defines an inner groove opening toward the inside of the circulation pipe 75. These protruding annular areas 103 are interconnected by recessed annular areas 105 outside the circulation pipe 75. The recessed annular areas 105 protrude toward the inside of the circulation pipe 75, and define grooves opening toward the outside of the circulation pipe 75 between the protruding annular areas 103. From a cross section in a plane containing the axis of the circulation pipe 75, the corrugated segment has a serpentine shape.

[0146] The circulation pipe 75 is straight and parallel to the central axis C.

[0147] The connection piece 23 also comprises an external thermal insulation 107 arranged between the intermediate pipe 35 and the outer pipe 27 .

[0148] The outer insulation 107 extends from the distal intermediate end 39 over a length that is less than 75% of the total length of the intermediate tube 35 .

[0149] The external insulation 107 is usually of the same type as the insulation 21. It comprises a plurality of aluminized metal sheets or plastic sheets (such as PET or polyethylene terephthalate, PA or polyamide, PEEK or polyetheretherketone) superimposed on each other with fiber layers interposed therebetween.

[0150] The outer insulation 107 is preferably pressed against the intermediate tube 35. It covers the weld connecting the intermediate distal end 39 to the annular ring 47. It also covers the radially outer surface of this annular ring 47. The outer insulation 107 extends over about 50% of the total length of the intermediate tube 35.

[0151] The connection piece 23 also includes an internal thermal insulation 109 arranged between the intermediate tube 35 and the inner tube 41 .

[0152] The inner insulation 109 extends from the inner proximal end 43 over a length that is less than 75% of the total length of the inner tube 41 .

[0153] The inner insulation 109 is of the same type as the insulation 21. It comprises a plurality of aluminized metal sheets or plastic sheets (e.g. PET, PA, PEEK) superimposed on each other with fiber layers interposed therebetween. It is pressed against the inner tube 41.

[0154] The inner insulation 109 does not cover the weld that connects the inner proximal end 43 to the valve block 73 or the motion limiter 81. It starts a short distance from the adhesive weld. It usually extends over about two-thirds of the total length of the inner tube 41.

[0155] Note that Figure 2 As shown in FIG, there is an axial overlap between the outer insulation 107 and the inner insulation 109.

[0156] As described above, common mechanical stresses such as emergency braking, sharp vehicle turns, vibrations and impacts caused by poor road conditions generate no more than 1 mm displacement of the inner proximal end 43. Therefore, these stresses do not cause contact between the motion limiter 81 and the edge of the aperture 79.

[0157] In contrast, if the storage unit 1 is subjected to abnormal stresses, such as in the case of an accidental vehicle impact, the inner proximal end 43 may be subjected to accelerations of up to 10G. In this case, the motion limiter 81 contacts the edge of the aperture 79. This will limit the deformation of the inner tube 41 and the intermediate tube 35. These tubes 41, 35 will not undergo irreversible plastic deformation. The motion limiter 81 is sufficiently rigid not to be deformed by such an impact.

[0158] Note that the outer insulation 107 covers only the area of ​​the intermediate tube 35 where the temperature difference between the intermediate tube 35 and the outer tube 27 is greatest. The outer tube 27 is at the temperature of the cryogenic fluid, i.e., approximately 20K in the case of liquid hydrogen. The temperature of the intermediate tube 35 varies between 50K at the intermediate proximal end 37 and 130K at the intermediate distal end 39. Therefore, the temperature difference near the intermediate distal end 39 is greater. Therefore, the radiation from the intermediate tube 35 to the outer tube 27 is greater at this point. Therefore, installing insulation on this portion of the intermediate tube 35 is a very effective way to limit radiative heat transfer without unduly increasing cost.

[0159] The internal insulation 109 is also positioned in the area where the temperature difference between the inner tube 41 and the intermediate tube 35 is greatest.

[0160] It should be noted that the conversion from a single tube to a suspension of two tubes (intermediate and inner tube) with low wall thickness, as disclosed in application number FR 2207054, enables, for a typical example (hydrogen storage of a capacity suitable for motor vehicles), the heat input to be reduced from 6.9 W to 4 W. By using particularly thin-walled tubes for the circulation of the cryogenic fluid, the heat transfer can be reduced from 5 W to 3.5 W for the same example.

[0161] According to an alternative not shown in the first embodiment, the inner proximal end 43 of the inner tube 41 extends and passes through the first central aperture 86. The first cup 83 is welded directly to the inner tube 41. The motion limiter 81 is arranged around the inner proximal end 43 and is rigidly attached thereto.

[0162] Reference now Figure 3An alternative to the first embodiment is disclosed. Only the alternative will be described in detail below. Figure 2 In both embodiments, elements that are identical or provide the same function will be indicated by the same reference numerals.

[0163] In an alternative embodiment, the movement restrictor 81 is a ring attached to the internal reservoir 3.

[0164] It engages with the inner proximal end 43 of the inner tube 41 .

[0165] Alternatively, it engages with a rigid member, namely the valve block 73, or it engages with both the inner proximal end 43 and the rigid member.

[0166] The motion restrictor 81 has an annular shape centered on the central axis C.

[0167] Advantageously, it is continuous.

[0168] Alternatively, it may consist of several individual segments arranged in a loop.

[0169] The movement restrictor 81 is attached to the inner ring 51 , typically on a face 111 of the inner ring 51 facing the exterior of the inner reservoir 3 .

[0170] A motion limiter 81 surrounds the aperture 79 and projects radially inwardly from the aperture 79 .

[0171] The inner proximal end 43 covers the outer surface 77 of the valve block 73. More specifically, it covers the portion of the outer surface 77 facing the inner reservoir 3.

[0172] Inner proximal end 43 is rigidly attached to valve block 73 by any suitable means, such as welding.

[0173] The end portion 76 of the valve block 73 engages in the inner proximal end 43. It has an outer cross section that is substantially the same as the inner cross section of the inner proximal end 43.

[0174] The first central portion 84 of the first cup 83 is rigidly attached directly to the inner proximal end 43 .

[0175] The inner proximal end 43 is engaged by the first central aperture 86 of the first cup 83 and is welded to the edge of said aperture 86 .

[0176] The motion limiter 81 has an inner diameter equal to the outer diameter of the inner proximal end 43 plus typically 4 mm.

[0177] After the intermediate tube 35 , the inner tube 41 , and the bottom 65 have been welded to the inner ring 51 , the motion limiter 81 is welded to the inner ring 51 .

[0178] The advantage of this solution is that once the suspension is assembled, the 2 mm gap between the motion limiter 81 and the inner tube 41 is adjusted. In other words, the position of the motion limiter 81 is adjusted by knowing the position of the inner proximal end 43 of the inner tube 41 relative to the inner ring 51.

[0179] Furthermore, the inner proximal end 43 of the inner tube 41 is elongated so that the inner tube 41 is welded directly to the first cup 83. This eliminates the need for the intermediate welds required in the first embodiment (welding the tube 41 to the valve block 73 and then welding the first cup 83 to the valve block 73). This also eliminates a connection on a critical path for heat load transfer.

[0180] Now refer to Figure 4 and Figure 5 The second embodiment of the present invention is disclosed. Figure 3 In both embodiments, elements that are the same or provide the same function will be represented by the same reference numerals.

[0181] This method is particularly applicable to a connection 25 which is not designed for the passage of cryogenic fluids.The connection 25 is designed to suspend the end of the first reservoir opposite to the fluid inlet and outlet orifices of the storage unit 1 .

[0182] Therefore, no valve block or cryogenic fluid circulation pipe is integrated into the connection piece 25 .

[0183] Instead, the connecting member 25 comprises a second cup 113 having a second central portion 115 and a second edge 117 rigidly attached to the external reservoir 7 ( Figure 1 ).

[0184] The second central portion 115 faces the bottom 13 of the internal reservoir 3. The second edge 117 is rigidly attached to the inner surface of the external reservoir 7. This second cup 113 is for example of the type disclosed in application number FR2211366.

[0185] The connector 25 includes a sliding tube 119 that passes through a second hole 120 in the second central portion 115 .

[0186] The slide tube 119 is coaxial with the central axis C.

[0187] It is rigidly attached to the second central part 115 , for example by welding.

[0188] The slide tube 119 extends opposite to the motion limiter 81 perpendicularly to the central axis C. In other words, the motion limiter 81 is arranged around the slide tube 119 .

[0189] The inner proximal end 43 of the inner tube 41 is slidably engaged in the sliding tube 119 .

[0190] The inner proximal end 43 is thus connected to the sliding tube 119 with one degree of freedom in axial translation.

[0191] like Figure 5 As shown in FIG. 1 , the inner surface of the sliding tube 119 has a coating 121 to facilitate the inner proximal end 43 to contact and slide with the sliding tube 119 .

[0192] For example, a radial gap of 2 mm is provided between the motion restrictor 81 and the slide tube 119 .

[0193] In this embodiment, the motion limiter 81 engages the inner tube 41 to limit the deflection of the inner tube indirectly through the sliding tube 119.

[0194] This sliding capability makes it possible to manage variations in the axial length of the internal reservoir 3 relative to the external reservoir 7. When the internal reservoir 3 is filled with a cryogenic fluid, this container 3 contracts under the effect of cooling. Its axial length decreases.

[0195] In the second embodiment, the connection piece 25 comprises a single layer of insulation 123 instead of the inner insulation 107 and the outer insulation 109. It is usually arranged against the inner tube 41 between the inner tube 41 and the intermediate tube 35.

[0196] It covers the inner cylindrical wall 63 and the majority of the inner tube 41. It stops at a short distance from the sliding tube 119.

[0197] According to an alternative that is not shown, the movement limiter 81 is attached to the sliding tube 119 .

[0198] It engages with an orifice 79 through which the inner tube 41 passes.

[0199] It has the form of a sleeve.

[0200] The memory cell disclosed above has several advantages.

[0201] Provided that the motion limiter engages with the aperture of the inner reservoir to limit the deflection of the inner tube, a particularly simple motion limiter may be used. The deflection is controlled by selecting an appropriate gap between the inner surface of the aperture and the motion limiter.

[0202] The fact that the motion restrictor is rigidly attached to the inner tube and / or the rigid member means that the motion restrictor can be conveniently positioned in the aperture.

[0203] The fact that the motion restrictor is engaged in the aperture over only less than 50% of its total length limits the transfer of radiation between the motion restrictor and the internal reservoir.

[0204] It also makes possible the use of a particularly simple motion limiter, provided that the motion limiter is attached to the internal reservoir and engages with the inner proximal end and / or the rigid member. The adjustment of the gap between the motion limiter and the inner tube is facilitated by the fact that once the suspension is assembled, the position of the motion limiter is adjusted knowing the position of the inner proximal end.

[0205] As described above, when the connection comprises a first cup having a first central portion rigidly attached directly to the inner proximal end and a first rim rigidly attached to the outer container, connection assembly is facilitated. The number of welds on the thermal load path is reduced.

[0206] When the connector includes a second cup having a second central portion and a second edge rigidly attached to the external reservoir, the connector includes a tube passing through an aperture in the second central portion and rigidly attached to the second central portion, the inner proximal end being slidably engaged in the tube, the tube extending perpendicular to the central axis relative to the motion restrictor, and the connector allows axial thermal expansion or contraction of the internal reservoir relative to the external reservoir.

[0207] Assuming that the connection comprises an intermediate tube arranged between the outer tube and the inner tube and an annular ring connecting the intermediate distal end to the inner distal end, this means that the heat path leading from the outer reservoir to the inner reservoir by conduction first passes through the inner tube, then through the annular ring, and then through the intermediate tube. The heat flow thus circulates through two tubes arranged one inside the other, and the heat flow path is therefore particularly long.

[0208] Furthermore, the presence of the movement restrictor means that an intermediate tube and an inner tube can be used, both tubes having a particularly low wall thickness of between 0.5 mm and 2.5 mm, which helps to reduce heat flow by conduction.

[0209] Assuming that the suspension includes an external insulation disposed between the intermediate tube and the outer tube and extending from the intermediate distal end over a length less than 75% of the total length of the intermediate tube, this is a very effective way of limiting the radiation transfer between the outer tube and the intermediate tube. The external insulation is placed in the area where the temperature difference between the two tubes is the greatest.

[0210] It is also possible to reduce the radiation transfer between the intermediate tube and the inner tube by providing that the suspension comprises an internal insulation which is arranged between the intermediate tube and the outer tube and which extends from the inner proximal end over a length which is less than 75% of the total length of the inner tube. Such an internal insulation is placed in the area where the temperature difference between the intermediate tube and the inner tube is the greatest.

[0211] When each circulation tube has a wall thickness between 0.1 mm and 0.6 mm, heat conduction from the outer reservoir to the inner reservoir can be greatly reduced.

[0212] In this case, it is advantageous to provide the circulation pipe with at least one thermal expansion compensator to allow for different expansions between the circulation pipe and the outer pipe.

[0213] It is particularly convenient and economical to produce the thermal expansion compensator in the form of a bellows segment.

[0214] The storage unit can be of many variants.

[0215] The connector may have neither an intermediate tube nor an annular ring. The inner tube is then attached directly to the base plate. For example, the connector is of the type disclosed in patent application number FR2207054.

[0216] The motion restrictor may not be in the form of a stepped washer. For example, the motion restrictor may be a simple cylindrical sleeve attached to a valve block or inner tube or the like.

[0217] The rigid member need not be a valve block. The rigid member may be, for example, a short tube, in particular a rigid short tube, attached to the inner proximal end and the first cup.

[0218] According to another alternative, a projection protruding outward from the inner reservoir may be formed around the aperture 79. The motion limiter may then be a cup attached to the valve block 73 having a raised edge toward the inner reservoir surface. The raised edge surrounds these projections and by engaging with the projections limits the deflection of the inner tube and valve block assembly.

[0219] The storage unit may have two connections with a circulation pipe 77 and a distributor module 73 , or may have two connections without a circulation pipe 77 or a distributor module 73 .

[0220] The connection without the circulation tube 77 or the valve group 73 may not include a sliding tube. In this case, the inner tube 41 is directly attached to the second cup 113. The motion limiter 81 is a sleeve mounted directly on the inner proximal end 43 of the inner tube, or attached to the internal reservoir 3 as described above.

Claims

1. A cryogenic fluid storage unit (1), comprising an inner reservoir (3) defining inwardly a cryogenic fluid storage volume (5), an outer reservoir (7) accommodating the inner reservoir (3), and a suspension (9) attaching the inner reservoir (3) to the outer reservoir (7), the suspension (9) comprising a connection (23), the connection comprising: - an outer tube (27) having an outer proximal end (29) attached to the inner reservoir (3) and an outer distal end (31) located inside the storage volume (5); - a bottom plate (33) closing the outer distal end (31); - an inner tube (41) arranged inside the outer tube (27), the inner tube having an inner proximal end (43) directly attached to a rigid member connected to the external reservoir (7) and having an inner distal end (45) attached to the internal reservoir (3); - a movement limiter (81) which limits the deflection of the inner tube (41) relative to the internal reservoir (3) in a plane perpendicular to the central axis (C) of the inner tube (41), the movement limiter (81): attached to the rigid member and / or the inner proximal end (43); Alternatively attached to the internal reservoir (3) and engaged with the rigid member and / or the inner proximal end (43).

2. A storage unit according to claim 1, wherein the internal reservoir (3) has an orifice (79), the inner tube (41) is connected to the external reservoir (7) through the orifice, and the movement limiter (81) engages with the orifice (79) to limit the deflection of the inner tube (41).

3. The storage unit according to claim 2, wherein the storage unit (1) comprises: - a valve block (73) having at least one internal passage (74) for a cryogenic fluid; - at least one circulation pipe (75) extending inside the inner pipe (41) and fluidically connecting the at least one internal channel (74) to the storage volume (5); The rigid component is the valve block (73).

4. A storage unit according to claim 2 or 3, wherein the movement limiter (81) has a specific axial length and is engaged in the aperture (79) over a length less than 50% of the specific length.

5. Storage unit according to any one of claims 2 to 4, wherein the movement limiter (81) is a sleeve arranged around the valve block (73) and / or the inner proximal end (43).

6. A storage unit according to claim 5, wherein the connecting member (23) includes a first cup body (83), the first cup body having a first central portion (84) directly and rigidly attached to the valve group (73) and / or the inner proximal end (43) and a first edge (85) rigidly attached to the external reservoir (7), the movement limiter (81) includes a cylindrical portion (87), which is arranged around the valve group (73) and / or the inner proximal end (43) and rigidly attached to the valve group (73) and / or the inner proximal end (43), and the movement limiter (81) also includes a protruding flange (88) rigidly attached to the first cup body (83).

7. The storage unit according to claim 1, wherein the movement restrictor (81) is a ring attached to the internal reservoir (3).

8. A cryogenic fluid storage unit (1), comprising an inner reservoir (3) defining inwardly a cryogenic fluid storage volume (5), an outer reservoir (7) accommodating the inner reservoir (3), and a suspension (9) attaching the inner reservoir (3) to the outer reservoir (7), the suspension (9) comprising a connection (23, 25), the connection comprising: - an outer tube (27) having an outer proximal end (29) attached to the inner reservoir (3) and an outer distal end (31) located inside the storage volume (5); - a bottom plate (33) closing the outer distal end (31); - an inner tube (41) arranged inside the outer tube (27), the inner tube having an inner proximal end (43) connected to the outer reservoir (7) and an inner distal end (45) attached to the inner reservoir (3); - a second cup (113) having a second central portion (115) and a second edge (117) rigidly attached to the external reservoir (7); a sliding tube (119) passing through a second orifice (121) in the second central part (115) and rigidly attached to the second central part (115), the inner proximal end (43) being slidably engaged in the sliding tube (119); - a movement limiter (81) which limits the deflection of the inner tube (41) relative to the internal reservoir (3) in a plane perpendicular to the central axis (C) of the inner tube (41), the movement limiter (81): attached to the sliding tube (119); Or attached to the internal reservoir (3) and engaged with the sliding tube (119).

9. A storage unit according to claim 8, wherein the sliding tube (119) extends perpendicularly to the central axis (C) opposite to the movement limiter (81).

10. Storage unit according to any of the preceding claims, wherein the connection (23, 25) comprises a plurality of tubes coaxial to each other and arranged inside each other, the inner tube belonging to the plurality of tubes and being the innermost tube of the plurality of tubes.

Images