Cryogenic fluid storage unit
The suspension design for cryogenic fluid storage units addresses heat transfer and mechanical stress challenges by using a connection system with limited displacement and thermal insulation, ensuring efficient and durable cryogenic fluid storage.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- FAURECIA HYDROGEN SOLUTIONS FRANCE
- Filing Date
- 2023-09-19
- Publication Date
- 2026-06-19
AI Technical Summary
Existing cryogenic fluid storage units face significant heat transfer issues through conduction due to the suspension connecting the internal and external reservoirs, which are exacerbated by mechanical stresses, leading to potential deformation and irreversible damage.
A suspension design with a connection system comprising an external and internal tube, a movement limiter, and thermal insulation to minimize heat transfer by conduction and deformation, using thin-walled tubes and limited displacement to manage mechanical stresses.
The solution effectively reduces heat transfer by conduction and deformation, maintaining the integrity of the storage unit under normal and exceptional mechanical stresses, while optimizing thermal insulation and tube thickness for efficient cryogenic fluid storage.
Smart Images
Figure 00000019_0000 
Figure 00000020_0000 
Figure 00000021_0000
Abstract
Description
Title of the invention: Cryogenic fluid storage unit
[0001] The present invention relates generally to a cryogenic fluid storage unit.
[0002] Such a storage unit may include an internal tank internally delimiting a cryogenic fluid storage volume, an external tank in which the internal tank is housed, and a suspension fixing the internal tank to the external tank.
[0003] In order to limit heat transfer by convection from the external reservoir to the internal reservoir, the space delimited between the internal reservoir and the external reservoir is typically maintained under a high vacuum.
[0004] Radiation transfers are limited by arranging a layer of insulating material on the inner reservoir.
[0005] Heat transfer by conduction from the external reservoir to the internal reservoir occurs mainly through the suspension.
[0006] They can be relatively high.
[0007] In this context, the invention aims to provide a storage unit whose suspension is designed to minimize the heat flow circulating by conduction from the external reservoir to the internal reservoir.
[0008] To this end, the invention relates to a cryogenic fluid storage unit, comprising an internal reservoir internally delimiting a cryogenic fluid storage volume, an external reservoir in which the internal reservoir is housed, and a suspension fixing the internal reservoir to the external reservoir, the suspension comprising a connection including:
[0009] - an external tube having an external proximal end fixed to the reservoir internal and an external distal end located inside the storage volume;
[0010] - a base plate closing the external distal end;
[0011] - an inner tube arranged inside the outer tube, having an end an internal proximal end connected to the external reservoir and an internal distal end fixed to the internal reservoir;
[0012] - a movement limiter, limiting the displacement of the inner tube relative to the internal reservoir in a plane perpendicular to a central axis of the internal tube.
[0013] The inner tube is designed only to withstand the usual mechanical stresses corresponding to normal use of the storage unit. When the storage unit is installed in a motor vehicle, these stresses result, for example, from emergency braking, a hairpin turn, or vibrations generated by the vehicle rolling on a poor road surface.
[0014] On the other hand, in the case where the storage unit is subjected to an exceptional stress such as an accidental shock, the movement limiter makes it possible to limit the movement of the inner tube in a plane perpendicular to the central axis of the inner tube.
[0015] This makes it possible to limit the deformation of the inner tube, preventing it from entering the plastic domain and thus from undergoing irreversible deformation.
[0016] In the absence of a motion limiter, the probability that the inner tube would be damaged in the event of exceptional stress would be significant.
[0017] The motion limiter thus makes it possible to choose a reduced wall thickness for the inner tube, just sufficient to withstand normal mechanical stresses. This helps to limit heat transfer by conduction from the external reservoir to the internal reservoir.
[0018] The fluid storage unit may further represent one or more of the following characteristics, considered individually or according to all technically possible combinations:
[0019] - the internal reservoir has an orifice through which the internal tube is connected to the external reservoir, the movement limiter cooperating with the orifice to limit the movement of the internal tube;
[0020] - the movement limiter being rigidly fixed to the inner tube;
[0021] - the storage unit comprises: - * a distribution block fixed to the proximal internal end of the internal tube and featuring at least one internal passage for the cryogenic fluid; * at least one circulation tube extending inside the inner tube and fluidly connecting at least one internal passage to the storage volume; the movement limiter being rigidly fixed to the distributor block;
[0022] - the motion limiter has a determined axial length and is engaged in the orifice to a length less than 50% of said determined length
[0023] - the motion limiter is fixed to the internal tank and cooperates with the end proximal internal;
[0024] - the connection comprises a first cup having a first central part rigidly fixed directly to the inner proximal end and a first edge rigidly fixed to the outer reservoir;
[0025] - the connection comprises a second cup having a second central part and a second edge rigidly fixed to the external reservoir, the connection comprising a sliding tube passing through a second orifice of the second central part and rigidly fixed to the second central part, the inner proximal end being engaged of sliding in the sliding tube, the sliding tube extending opposite the movement limiter perpendicular to the central axis.
[0026] Other features and advantages of the invention will become apparent from the detailed description given below, by way of example and not limitation, with reference to the accompanying figures, among which: - [Fig.l] The [Fig.l] is an axial section view of the cryogenic fluid storage unit; - [Fig.2] The [Fig.2] is an enlarged axial section view of part of the suspension of the storage unit of the [Fig.1]; - [Fig.3] Fig.3 is a view similar to that of Fig.2, illustrating a second embodiment, - [Fig. 4] [Fig. 4] is a view similar to that of [Fig. 2], illustrating a third embodiment for a connection that does not involve the passage of cryogenic fluid conduits; and - [Fig.5] The [Fig.5] is an enlarged view of a detail V of the [Fig.4].
[0027] In figures 2 to 5, some welds joining the parts to each other are not shown.
[0028] The storage unit 1 shown in [Fig.1] is intended to store a cryogenic fluid.
[0029] Cryogenic fluid is understood to mean a fluid at a very low temperature, which may be at least partially in a liquid state inside the storage unit.
[0030] This fluid is typically hydrogen. Alternatively, the fluid is helium, nitrogen, a natural gas such as methane CH4, air, or any other suitable fluid.
[0031] This storage unit is typically intended to be carried on board a vehicle having an electric propulsion engine, for example a motor vehicle, a train, a boat or any other vehicle.
[0032] The motor vehicle is for example a car, a utility vehicle, a truck, etc.
[0033] The storage unit 1 is intended to power a fuel cell. The fuel cell is configured to produce electricity and electrically power the electric propulsion motor of the vehicle.
[0034] The cryogenic fluid storage unit 1 comprises an internal reservoir 3 internally delimiting a cryogenic fluid storage volume 5, an external reservoir 7 inside which the internal reservoir 3 is housed, and a suspension 9 fixing the internal reservoir 3 to the external reservoir 7.
[0035] In the example shown, the internal reservoir 3 has a horizontal central axis C.
[0036] The internal reservoir 3 comprises a ferrule 11, closed at its two axial ends by bottoms 13.
[0037] The ferrule 11 is cylindrical, centered on the central axis C.
[0038] The external reservoir 7 is also horizontally oriented.
[0039] It comprises a ferrule 15, closed at its two axial ends by bottoms 17.
[0040] The ferrule 15 is cylindrical, centered on the central axis C.
[0041] The internal reservoir 3 and the external reservoir 7 delimit between them a space intermediate 19, maintained under a high vacuum.
[0042] This vacuum is typically on the order of 105 mbar, so as to strongly limit the heat transfer by convection from the external reservoir 7 to the internal reservoir 3.
[0043] A thermal insulation 21 is interposed between the inner tank 3 and the outer tank 7. The thermal insulation 21 is typically placed on the outer surface of the inner tank 3. The thermal insulation 21 comprises, for example, a plurality of metal sheets superimposed one on top of the other, with interposed layers of fibers.
[0044] The suspension 9 is arranged so that the entire weight of the internal reservoir 3 is taken up by the external reservoir 7 via the suspension 9.
[0045] The weight of the internal reservoir 3 is understood here to include the weight of the cryogenic fluid stored in the internal reservoir 3.
[0046] The accelerations experienced by the internal reservoir 3 and the cryogenic fluid contained in the internal reservoir 3 are also transmitted to the external reservoir 7 via the suspension 9.
[0047] When the storage unit 1 is mounted in a vehicle, these accelerations result from changes in the direction of the vehicle, braking applied to the vehicle or acceleration of the vehicle, roughness or irregularities of the road, or shocks applied to the vehicle.
[0048] In the example shown, the suspension 9 comprises two links 23, 25.
[0049] The links 23, 25 each suspend one of the two opposite axial ends of the internal reservoir 3 from the external reservoir 7.
[0050] Links 23 and 25 are different from each other.
[0051] The link 23 is intended to allow the passage of cryogenic fluid to, or from, the storage volume 5.
[0052] On the contrary, link 25 is not intended for the passage of cryogenic fluid.
[0053] As illustrated in [Fig.2], link 23 comprises:
[0054] - an external tube 27 having an external proximal end 29 fixed to the reservoir internal 3 and an external distal end 31 located inside the storage volume 5;
[0055] - a base plate 33 closing the external distal end 31;
[0056] - an inner tube 41 arranged inside the outer tube 31, having an end proximal internal 43 linked to external reservoir 7 and a distal internal end 45 fixed to internal reservoir 3.
[0057] Link 23 also includes: .
[0058] - an intermediate tube 35 arranged inside the outer tube 27, having a intermediate proximal end 37 fixed to the internal reservoir 3 and an intermediate distal end 39; and
[0059] - an annular ring 47 connecting the intermediate distal end 39 to the end distal internal 45.
[0060] Thus, the internal distal end 45 is fixed to the internal reservoir 3 via the annular ring 47 and the intermediate tube 35.
[0061] The external tube 27 is substantially cylindrical, and is coaxial with the central axis C.
[0062] It is located inside storage volume 5, typically entirely inside storage volume 5.
[0063] An opening 49 is provided in the bottom 13 of the internal reservoir 3. An internal ring 51 is engaged in the opening 49 and rigidly fixed to the bottom 13. The external peripheral edge of the internal ring 51 is welded in a hermetic manner to the edge of the opening 49.
[0064] On a face turned towards the storage volume 5, the inner ring 51 has an external rib 53 of substantially cylindrical shape.
[0065] The external rib 53 is coaxial with the central axis C, and has substantially the same diameter as the external proximal end 29.
[0066] The external proximal end 29 is welded tightly to the external rib 53.
[0067] Similarly, the inner ring 51 has on its face facing the storage volume 5 a second rib 55, of substantially cylindrical shape.
[0068] This second rib 55 is coaxial with the central axis C, and has the same diameter as the intermediate proximal end 37.
[0069] The intermediate proximal end 37 is welded tightly to the second rib 55.
[0070] The base plate 33 seals the external distal end 31. It has a base 57 extended by a raised edge 59 welded securely to the external distal end 31.
[0071] The bottom 57 is convex towards the inside of the storage volume 5.
[0072] The annular ring 47 is coaxial with the central axis C.
[0073] It has U-shaped sections in radial planes containing the central axis C. The annular ring 47 thus has an external cylindrical wall 61 and an internal cylindrical wall 63, connected to each other by a bottom 65.
[0074] The outer wall 61 has substantially the same diameter as the intermediate distal end 39, and is welded to this intermediate distal end 39.
[0075] The internal wall 63 has substantially the same diameter as the internal proximal end 45, and is welded to it.
[0076] The intermediate tube 35 has a wall thickness of between 0.5 mm and 2.5 mm, preferably between 0.5 and 1.5 mm, and for example 1 mm.
[0077] It is made of an austenitic stainless steel having, for example, an Rp 0.2 of 270 MPa. Typically, it is made of stainless steel of grade 1.4310 or type 304.
[0078] The intermediate proximal end 37 and the intermediate distal end 39 are for example encircled by sleeves 67, so as to increase the rigidity respectively of the connection with the rib 55 and of the connection with the outer wall 61.
[0079] Similarly, the inner tube 41 has a wall thickness of between 0.5 mm and 2.5 mm, preferably between 0.5 and 1.5 mm, and for example 1 mm.
[0080] It is made of an austenitic stainless steel having, for example, an Rp 0.2 of 270 MPa. Typically, it is made of stainless steel of grade 1.4310 or type 304.
[0081] The internal proximal end 43 and the internal distal end 45 are for example encircled by sleeves 71, so as to increase the rigidity respectively of the connection with the internal wall 63 and of the connection with a distributing block 73.
[0082] The distribution block 73 is fixed to the internal proximal end 43 of the internal tube 4L
[0083] The distributor block 73 has at least one internal passage 74 for the fluid cryogenic.
[0084] The storage unit 1 further comprises at least one circulation tube 75 extending inside the inner tube 41 and fluidly connecting at least one internal passage 74 to the storage volume 5.
[0085] Typically, the distributor block 73 has four internal passages 74, connected to four circulation tubes 75.
[0086] In this case, one of the passages 74, and the corresponding tube 75, are provided for filling the storage volume 5. Another passage 74, and the corresponding tube 75, are provided for emptying the storage volume 5.
[0087] The two other passages 74, and the two other corresponding tubes 75, are intended to circulate the cryogenic fluid to a heat exchanger, in a loop.
[0088] The distributor block 73 is placed axially in the extension of the inner tube 4L
[0089] It has, towards the inner tube 41, a substantially cylindrical end part 76.
[0090] The end part 76 is coaxial with the central axis C. It is delimited radially outwards by an external surface 77, and axially towards the internal tube 41 by a connecting surface 78.
[0091] The external surface 77 is substantially cylindrical. It has a cross-section perpendicular to the central axis C substantially identical to that of the internal proximal end 43.
[0092] The internal proximal end 43 is connected to the peripheral edge of the connecting surface 78.
[0093] The internal reservoir 3 further includes an orifice 79 through which the internal tube 41 is connected to the external reservoir 7.
[0094] The orifice 79 is provided in the inner ring 51. The sub-assembly consisting of the distributor block 73 and the inner tube 41 passes through the orifice 79.
[0095] Thus, the space delimited inside the external tube 27 is isolated from the storage volume 5 but communicates with the intermediate space 19 through the orifice 79.
[0096] Advantageously, the link 23 includes a movement limiter 81, limiting a displacement of the inner tube 41 relative to the inner reservoir 3, in a plane perpendicular to the central axis of the inner tube 41, to a maximum of less than 3 mm.
[0097] In the example shown, the central axis of the internal tube 41 corresponds to the central axis C. The travel of the internal tube 41 is taken at the level of the internal proximal end 43. It corresponds to the radial displacement of the internal proximal end 43 relative to its rest position.
[0098] The maximum is fixed, as indicated above, at a value less than 3 mm, typically between 1.5 and 2.5 mm, and worth for example 2 mm.
[0099] The motion limiter 81 cooperates with the orifice 79 to limit the movement of the inner tube 4L
[0100] The motion limiter 81 is rigidly fixed to the distributor block 73.
[0101] Alternatively, it is fixed to the internal tube 41, typically at the internal proximal end 43.
[0102] According to another embodiment, it is fixed both to the distributor block 73 and to the internal tube 4L
[0103] The movement limiter 81 is a sleeve arranged around the internal proximal end 43. The radial distance between the movement limiter 81 and the internal surface of the orifice 79 thus corresponds to the maximum travel of the internal tube 4L
[0104] Advantageously, the link 23 comprises a first cup 83 of which a first central part 84 is placed opposite the bottom 13 of the internal reservoir 3 and of which the first edge 85 is rigidly fixed to the internal surface of the external reservoir 7. This cup is, for example, of the type described in the application filed under number FR2211366.
[0105] The first central part 84 of the cup 83 is oriented substantially perpendicular to the central axis C. It has a first central orifice 86, through which the distribution block 73 passes.
[0106] The motion limiter 81 is advantageously a shouldered washer.
[0107] It has a cylindrical part 87, arranged around the distributor block 73 and rigidly fixed to it. An outward-extending collar 88 is formed at one end of the cylindrical part 87. The outward-extending collar 88 is rigidly fixed to the first cup 83, around the first central orifice 86.
[0108] Only the end 89 of the cylindrical part 87, opposite the protruding collar 88, is engaged in the orifice 79 of the internal reservoir 3.
[0109] Thus, if the movement limiter 81 has a determined total axial length, this movement limiter 81 is engaged in the orifice 79 only over a length less than 50% of said determined total length.
[0110] This helps to avoid excessive heat transfer by radiation between the motion limiter 81 and the edge of the orifice 79.
[0111] Each internal passage 74 has, at one end, a counterbore 93 formed in the connecting surface 78. A connecting sleeve 95 is rigidly fixed in this counterbore 93. The corresponding circulation tube 75 is rigidly fixed by one of its ends, in a watertight manner, to the connecting sleeve 95.
[0112] Furthermore, each circulation tube 75 is connected to the bottom plate 33 and communicates with the storage volume 5 through the bottom plate 33.
[0113] To do this, the base plate 33 has orifices 97, in which other connecting sleeves 99 are engaged. Each circulation tube 75 is rigidly fixed, in a watertight manner, to one of the other connecting sleeves 99.
[0114] Each circulation tube 75 has a wall thickness of between 0.1 and 0.6 mm, preferably between 0.2 and 0.4 mm, and for example 0.3 mm. These circulation tubes 75 are typically made of 316L type stainless steel.
[0115] In order to compensate for the differential expansion between the or each circulation tube 75 and the external tube 27, the or each circulation tube 75 includes at least one thermal expansion compensator 101.
[0116] Indeed, the circulation tube(s) 75 may have a temperature significantly lower than that of the external tube 27, particularly during the initial filling of the storage volume 5. During this initial filling, the storage volume 5 is at ambient temperature, as is the external tube 27. In contrast, the circulation tubes 75 are at approximately the same temperature as the cryogenic fluid. For a circulation tube 75 of 420 mm, the contraction in length of the tube circulation 75 can then reach 1.6 mm when the cryogenic fluid is liquid hydrogen at 20 K.
[0117] In the example shown, each circulation tube 75 has several thermal expansion compensators 101, distributed along its length.
[0118] For example, it includes three thermal expansion compensators 101, regularly spaced along the circulation tube 75.
[0119] The thermal expansion compensator or each 101 is advantageously a corrugated section of the circulation tube 75.
[0120] Each corrugated section comprises a plurality of annular zones 103 projecting outwards from the circulation tube 75, each defining an internal groove open towards the inside of the circulation tube 75. These projecting annular zones 103 are connected to each other by annular zones 105 recessed outwards from the circulation tube 75. The recessed annular zones 105 are convex towards the inside of the circulation tube 75, and define between the projecting annular zones 103 a groove open towards the outside of the circulation tube 75. Considered in section in a plane containing the axis of the circulation tube 75, the corrugated section has a sinuous shape.
[0121] The circulation tubes 75 are straight and parallel to the central axis C.
[0122] The connection 23 further includes an external thermal insulation 107, arranged between the intermediate tube 35 and the external tube 27.
[0123] This external thermal insulation 107 extends from the intermediate distal end 39 over a length less than 75% of the total length of the intermediate tube 35.
[0124] The external thermal insulation 107 is typically of the same type as the thermal insulation 21. It comprises a plurality of metallic or plastic sheets (for example of PET or polyethylene terephthalate, PA or polyamide, PEEK or aluminized polyetheretherketone) superimposed one on the other, with interposed layers of fibers.
[0125] The external thermal insulation 107 is preferably pressed against the intermediate tube 35. It covers the weld joining the intermediate distal end 39 to the annular ring 47. It also covers the radially external surface of this annular ring 47. The external thermal insulation 107 extends over approximately 50% of the total length of the intermediate tube 35.
[0126] The connection 23 further includes internal thermal insulation 109, arranged between the intermediate tube 35 and the inner tube 4L
[0127] This internal thermal insulation 109 extends from the internal proximal end 43 over a length less than 75% of the total length of the internal tube 4L
[0128] The internal thermal insulation 109 is of the same type as the thermal insulation 21. It comprises a plurality of metal or plastic sheets (e.g., PET, PA, PEEK) aluminized, superimposed one on the other, with interposed layers of fibers. It is pressed against the internal tube 41.
[0129] The internal thermal insulation 109 does not cover the weld connecting the inner proximal end 43 to the distribution block 73 or the movement limiter 81. It begins a short distance from the connecting weld. It typically extends over approximately two-thirds of the total length of the inner tube 4L
[0130] It will be noted that there is an axial overlap between the external thermal insulation 107 and the internal thermal insulation 109, as illustrated in [Fig.2].
[0131] As explained above, typical mechanical stresses such as emergency braking, sharp turns, vibrations, and shocks resulting from poor road surface conditions cause displacements of the inner proximal end 43 that do not exceed 1 mm. These stresses therefore do not result in contact between the movement limiter 81 and the edge of the orifice 79.
[0132] Conversely, if the storage unit 1 is subjected to exceptional stress, such as in the event of an accidental vehicle impact, the inner proximal end 43 may be subjected to an acceleration of up to 10 G. In this case, the motion limiter 81 comes into contact with the edge of the orifice 79. This will limit the deformation of the inner tube 41 and the intermediate tube 35. These tubes 41 and 35 will not undergo irreversible plastic deformation. The motion limiter 81 is sufficiently rigid not to be deformed during such an impact.
[0133] It should be noted that the external thermal insulation 107 only covers the area of the intermediate tube 35 where the temperature difference between the intermediate tube 35 and the external tube 27 is greatest. Indeed, the external tube 27 is at the temperature of the cryogenic fluid, i.e., approximately 20 K in the case where this fluid is liquid hydrogen. The temperature of the intermediate tube 35 varies between 50 K at the proximal intermediate end 37 and 130 K at the distal intermediate end 39. The temperature difference is therefore greater near the distal intermediate end 39. Consequently, the radiation from the intermediate tube 35 to the external tube 27 is greater at this point. Therefore, implementing thermal insulation on this portion of the intermediate tube 35 makes it very effective to limit heat transfer by radiation, without excessively increasing the cost.
[0134] The internal thermal insulation 109 is also placed in the area where the temperature difference between the inner tube 41 and the intermediate tube 35 is greatest.
[0135] It should be noted that the transition from a suspension with two tubes (intermediate tube and inner tube) with thin wall thickness to a single tube, as described The application filed under number FR2207054 allows for a reduction in thermal inputs from 6.9 W to 4 W for a typical embodiment (hydrogen storage with a capacity suitable for a motor vehicle). The use of particularly thin-walled cryogenic fluid circulation tubes reduces heat transfer from 5 W to 3.5 W for the same embodiment.
[0136] According to an unrepresented variant of the first embodiment, the internal proximal end 43 of the internal tube 41 is extended and passes through the first central orifice 86. The first cup 83 is welded directly onto the internal tube 4L. The movement limiter 81 is arranged around the internal proximal end 43 and rigidly fixed thereto.
[0137] A second embodiment will now be described, with reference to [Fig. 3]. Only the points by which the second embodiment differs from the first embodiment will be detailed below. Identical elements or elements performing the same function will be designated by the same reference numerals in both embodiments.
[0138] In the second embodiment, the motion limiter 81 is fixed to the internal reservoir 3.
[0139] It cooperates with the internal proximal end 43 of the internal tube 4L
[0140] Alternatively, it cooperates with the distributing block 73, or it cooperates with both the internal proximal end 43 and the distributing block 73.
[0141] The motion limiter 81 has an annular shape, centered on the central axis C.
[0142] Advantageously, it is continuous.
[0143] Alternatively, it is formed of several distinct segments, separated from each other, arranged in a ring.
[0144] The motion limiter 81 is fixed to the inner ring 51, typically on a face 111 of the inner ring 51 facing outwards from the inner reservoir 3.
[0145] The motion limiter 81 surrounds the orifice 79 and protrudes radially into the orifice 79.
[0146] The internal proximal end 43 covers the external surface 77 of the distributing block 73. More precisely, it covers the part of the external surface 77 located towards the internal reservoir 3.
[0147] The internal proximal end 43 is rigidly fixed to the distributor block 73, by any suitable means, for example by welding.
[0148] The end portion 76 of the distributing block 73 is engaged in the internal proximal end 43. It has an external section substantially identical to the internal section of the internal proximal end 43.
[0149] The first central part 84 of the first cup 83 is rigidly fixed directly to the internal proximal end 43.
[0150] The internal proximal end 43 is engaged through the first central orifice 86 of the first cup 83 and is welded to the edge of said orifice 86.
[0151] The motion limiter 81 has an inner diameter equal to the outer diameter of the inner proximal end 43, typically increased by 4 mm.
[0152] The motion limiter 81 is welded onto the inner ring 51 once the intermediate tube 35, the inner tube 41 and the bottom 65 are already welded to the inner ring 51.
[0153] The advantage of this solution lies in the fact that the 2 mm clearance between the movement limiter 81 and the inner tube 41 is adjusted once the suspension is assembled. In other words, the position of the movement 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.
[0154] Furthermore, the proximal inner end 43 of the inner tube 41 is extended so that the inner tube 41 is welded directly to the first cup 83. This avoids an intermediate weld that the first embodiment required (welding the tube 41 to the distributor block 73 and then welding the first cup 83 to the distributor block 73). This also eliminates a connection on the critical path of the heat transfer.
[0155] A third embodiment will now be described, with reference to Figures 4 and 5. Only the points in which the third embodiment differs from the second will be detailed below. Identical elements or elements performing the same function will be designated by the same reference numerals in both embodiments.
[0156] This embodiment is particularly well suited to the connection 25, which is not intended for the passage of the cryogenic fluid. The connection 25 is intended for the suspension of the end of the first tank located opposite the fluid inlet and outlet ports of the storage unit 1.
[0157] Consequently, no distributor block and no cryogenic fluid circulation tube are integrated into the link 25.
[0158] The link 25 includes, on the other hand, a second cup 113 having a second central part 115 and a second edge 117 rigidly fixed to the external reservoir 7 ([Fig.1]).
[0159] The second central part 115 is placed opposite the bottom 13 of the inner reservoir 3. The second edge 117 is rigidly fixed to the inner surface of the outer reservoir 7. This second cup 113 is, for example, of the type described in the application filed under number FR2211366.
[0160] The link 25 includes a sliding tube 119 passing through a second orifice 120 of the second central part 115.
[0161] The sliding tube 119 is coaxial with the central axis C.
[0162] It is rigidly fixed to the second central part 115, for example by welding.
[0163] The sliding tube 119 extends opposite the motion limiter 81 perpendicularly to the central axis C. In other words, the motion limiter 81 is arranged around the sliding tube 119.
[0164] The internal proximal end 43 of the internal tube 41 is slidably engaged in the sliding tube 119.
[0165] The internal proximal end 43 is therefore linked to the sliding tube 119 with one degree of freedom, in axial translation.
[0166] As seen in [Fig.5], an internal surface of the sliding tube 119 has a coating 121 facilitating the sliding of the internal proximal end 43 in contact with the sliding tube 119.
[0167] For example, a radial clearance of 2 mm is provided between the movement limiter 81 and the sliding tube 119.
[0168] In this embodiment, the motion limiter 81 cooperates with the inner tube 41 to limit the movement of this inner tube, indirectly through the sliding tube 119.
[0169] This sliding mechanism allows for managing the variation in axial length of the internal reservoir 3 relative to the external reservoir 7. During the filling of the internal reservoir 3 with cryogenic fluid, this reservoir 3 will contract under the effect of cooling. Its axial length decreases.
[0170] In the third embodiment, the connection 25 comprises a single layer of thermal insulation 123, replacing the internal thermal insulation 107 and external thermal insulation 109. It is arranged between the inner tube 41 and the intermediate tube 35, typically against the inner tube 4L
[0171] It covers the internal cylindrical wall 63, and most of the internal tube 4L. It stops a short distance from the sliding tube 119.
[0172] According to an unrepresented variant, the movement limiter 81 is a sleeve fixed to the sliding tube 119.
[0173] It cooperates with the orifice 79 through which the internal tube 4L passes
[0174] The storage unit described above has multiple advantages.
[0175] Providing that the motion limiter cooperates with the orifice of the internal reservoir to limit the movement of the internal tube allows the use of a particularly simple motion limiter. The movement is controlled by appropriately choosing the gap between the internal surface of the orifice and the motion limiter.
[0176] Providing that the motion limiter is rigidly fixed to the inner tube and / or the distributor block allows the motion limiter to be arranged very conveniently in the orifice.
[0177] Providing that the motion limiter is engaged in the orifice only for a length less than 50% of its total length, makes it possible to limit the transfers by radiation between the motion limiter and the internal reservoir.
[0178] Providing that the movement limiter is fixed to the inner reservoir and cooperates with the inner proximal end also allows for the use of a particularly simple movement limiter. Adjusting the clearance between the movement limiter and the inner tube is facilitated, since the position of the movement limiter is adjusted after the suspension is assembled, knowing the position of the inner proximal end.
[0179] When the connection comprises a first cup having a first central portion rigidly fixed directly to the inner proximal end and a first edge rigidly fixed to the outer reservoir, the assembly of the connection is facilitated, as explained above. The number of welds in the path of the thermal loads is reduced.
[0180] When the link comprises a second cup having a second central part and a second edge rigidly fixed to the external reservoir, the link comprising a tube passing through an orifice of the second central part and rigidly fixed to the second central part, the inner proximal end being slidably engaged in the tube, the tube extending opposite the movement limiter perpendicular to the central axis, the link allows thermal expansion or retraction of the internal reservoir, axially, relative to the external reservoir.
[0181] By providing that the connection includes 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, the thermal path leading from the outer reservoir to the inner reservoir by conduction passes first through the inner tube, then through the annular ring, and finally through the intermediate tube. The heat flow thus circulates in two tubes arranged one inside the other, such that the heat flow path is particularly long.
[0182] Furthermore, the presence of the motion limiter makes it possible to use an intermediate tube and an inner tube both having a particularly low wall thickness, between 0.5 mm and 2.5 mm, which helps to reduce the heat flow by conduction.
[0183] Providing that the suspension includes external thermal insulation, arranged between the intermediate tube and the outer tube, and extending from the distal end of the intermediate tube over a length less than 75% of the total length of the intermediate tube, makes it possible to very effectively limit radiation transfer between the outer tube and the intermediate tube. The external thermal insulation is placed in the area where the temperature difference is greatest between the two tubes.
[0184] Providing that the suspension includes internal thermal insulation, arranged between the intermediate tube and the outer tube, and extending from the inner proximal end for a length less than 75% of the total length of the inner tube, also helps to reduce radiation transfer between the intermediate tube and the inner tube. This internal thermal insulation is placed in the area where the temperature difference is greatest between the intermediate tube and the inner tube.
[0185] When each circulation tube has a wall thickness between 0.1 and 0.6 mm, it is possible to drastically reduce heat transfer by conduction from the external reservoir to the internal reservoir.
[0186] In this case, it is advantageous to provide that the circulation tube includes at least one thermal expansion compensator, to allow differential expansion between the circulation tube and the external tube.
[0187] Making the thermal expansion compensator in the form of a section of corrugated tube is particularly convenient and economical.
[0188] The storage unit may have multiple variants.
[0189] The connection may not include an intermediate tube and an annular ring. The inner tube is then directly attached to the base plate. The connection is, for example, of the type described in application number FR2207054.
[0190] The motion limiter may not be in the form of a shouldered washer. For example, the motion limiter may be a simple cylindrical sleeve, fixed to the distributor block or to the inner tube.
[0191] According to another embodiment, ridges could be formed around the orifice 79, projecting outwards from the inner reservoir. The movement limiter can then be a cup fixed to the distributor block 73, with an edge raised towards the surface of the inner reservoir. The raised edge surrounds the ridges and limits the movement of the assembly consisting of the inner tube and the distributor block by cooperating with the ridges.
[0192] The storage unit may have two connections with the circulation tubes 77 and the distribution block 73, or two connections without circulation tubes 77 or distribution block 73.
[0193] The connection without circulation tubes 77 or distributor block 73 may not include a sliding tube. In this case, the inner tube 41 is directly attached to the second cup 113. The movement limiter 81 is a sleeve mounted directly on the inner proximal end 43 of the inner tube, or is attached to the inner reservoir 3 as described above.
Claims
Demands
1. Cryogenic fluid storage unit (1), comprising an internal reservoir (3) internally delimiting a cryogenic fluid storage volume (5), an external reservoir (7) in which the internal reservoir (3) is housed, and a suspension (9) attaching the internal reservoir (3) to the external reservoir (7), the suspension (9) comprising a link (23) having: - an external tube (27) having an external proximal end (29) attached to the internal reservoir (3) and an external distal end (31) located inside the storage volume (5); - a bottom plate (33) closing the external distal end (31); - an internal tube (41) arranged inside the external tube (27), having an internal proximal end (43) connected to the external reservoir (7) and an internal distal end (45) attached to the internal reservoir (3);the storage unit (1) comprising: - a distribution block (73) fixed to the inner proximal end (43) of the inner tube (41) and having at least one internal passage (74) for the cryogenic fluid; - at least one circulation tube (75) extending inside the inner tube (41) and fluidly connecting the at least one internal passage (74) to the storage volume (5); the connection (23) comprising a movement limiter (81), limiting a displacement of the inner tube (41) relative to the inner reservoir (3) in a plane perpendicular to a central axis (C) of the inner tube (41); the movement limiter (81) being rigidly fixed to the distribution block (73) and / or to the inner proximal end (43).
2. Storage unit according to claim 1, wherein the internal tank (3) has an orifice (79) through which the internal tube (41) is connected to the external tank (7), the movement limiter (81) cooperating with the orifice (79) to limit the movement of the internal tube (41).
3. Storage unit according to any one of claims 1 to 2, wherein the motion limiter (81) has an axially determined length and is engaged in the orifice (79) for a length less than 50% of said determined length.
4. Cryogenic fluid storage unit (1), comprising an internal reservoir (3) internally delimiting a cryogenic fluid storage volume (5), an external reservoir (7) in which the internal reservoir (3) is housed, and a suspension (9) attaching the internal reservoir (3) to the external reservoir (7), the suspension (9) comprising a link (23) having: - an external tube (27) having an external proximal end (29) attached to the internal reservoir (3) and an external distal end (31) located inside the storage volume (5); - a bottom plate (33) closing the external distal end (31); - an internal tube (41) arranged inside the external tube (27), having an internal proximal end (43) connected to the external reservoir (7) and an internal distal end (45) attached to the internal reservoir (3);the storage unit (1) comprising: - a distribution block (73) fixed to the inner proximal end (43) of the inner tube (41) and having at least one internal passage (74) for the cryogenic fluid; - at least one circulation tube (75) extending inside the inner tube (41) and fluidly connecting the at least one internal passage (74) to the storage volume (5); the connection (23) comprising a motion limiter (81), limiting a movement of the inner tube (41) relative to the inner reservoir (3) in a plane perpendicular to a central axis (C) of the inner tube (41); wherein the motion limiter (81) is fixed to the inner reservoir (3) and cooperates with the distribution block (73) and / or the inner proximal end (43).
5. Storage unit according to claim 4, wherein the linkage (23) comprising a first cup (83) having a first central part (84) rigidly fixed directly to the inner proximal end (43) and a first edge (85) rigidly fixed to the external reservoir (7).
6. A cryogenic fluid storage unit (1) comprising an internal reservoir (3) internally delimiting a cryogenic fluid storage volume (5), an external reservoir (7) in which the internal reservoir (3) is housed, and a suspension (9) securing the internal reservoir (3) to the external reservoir (7), the suspension (9) comprising a link (25) including: - an external tube (27) having an external proximal end (29) fixed to the internal reservoir (3) and an external distal end (31) located inside the storage volume (5); - a base plate (33) closing the external distal end (31); - an internal tube (41) arranged inside the external tube (27), having an internal proximal end (43) connected to the external reservoir (7) and an internal distal end (45) fixed to the internal reservoir (3); - a second cup (113) having a second central part (115) and a second edge (117) rigidly fixed to the external reservoir (7); - a sliding tube (119) passing through a second orifice (121) of the second central part (115) and rigidly fixed to the second central part (115), the internal proximal end (43) being slidably engaged in the sliding tube (119), - a movement limiter (81), limiting a movement of the internal tube (41) relative to the internal reservoir (3) in a plane perpendicular to a central axis (C) of the internal tube (41); in which the motion limiter (81) is fixed to the inner reservoir (3), the sliding tube (119) extending opposite the motion limiter (81) perpendicular to the central axis (C) such that the motion limiter (81) cooperates with the inner tube (41) to limit the movement of the inner tube (41) indirectly through the sliding tube (119); or in which the inner reservoir (3) has an orifice (79) through which the inner tube (41) is connected to the outer reservoir (7), the motion limiter (81) being fixed to the sliding tube (119) and cooperating with the orifice (79) to limit the movement of the inner tube (41).