Cryogenic fluid storage unit and vehicle comprising such a unit

Abstract

Cryogenic fluid storage unit and vehicle comprising such a unit The storage unit (1) comprises: - an internal tank (3); - an external tank (7), the internal tank (3) and the external tank (7) being separated from each other by an intermediate space (9); - a cryogenic fluid transfer element (19) housed in the intermediate space (9), the transfer element (19) comprising a body (23) delimiting a chamber (25), a suction (27) connecting the chamber (25) with the cryogenic fluid storage volume (5) delimited in the internal tank (3), a discharge (29), a movable element (31) configured to move relative to the body (23) by varying the volume of the chamber (25), a motor (33), and a mechanical transmission (35) transmitting motion from an output shaft (37) of the motor (33) to the movable element (31);the moving part (31) being connected to the body (23) by a bellows (47) isolating the motor (33) and the mechanical transmission (35) from the cryogenic fluid. Figure for the abbreviation: 4;

Description

Title of the invention: Cryogenic fluid storage unit and vehicle comprising such a unit

[0001] The present invention relates generally to the storage of a cryogenic fluid.

[0002] A storage unit intended to receive cryogenic hydrogen is These storage tanks are typically designed to withstand internal pressures between 1 and 27 bar. Beyond this pressure, the internal tank walls of the storage unit must be significantly thicker, and the unit's mass becomes very substantial. This is particularly problematic for storage units intended for installation in vehicles.

[0003] For applications where hydrogen is used in an internal combustion engine, the hydrogen injection pressure is in the range of 40 to 200 bar. This is because it is necessary to inject the hydrogen directly into the engine cylinders when the intake valves are closed, i.e., when the piston is on its upward stroke. It is therefore essential to supply the hydrogen at a pressure higher than the normal cylinder pressure. Furthermore, high-pressure injection results in a more homogeneous mixture and improves combustion quality.

[0004] The internal combustion engine must therefore be supplied with a transfer device that increases the pressure of the cryogenic fluid.

[0005] Piston pumps can be used for this purpose.

[0006] The reliability of such pumps is very low. The motor bearings have a short service life.

[0007] In this context, the invention aims to provide a cryogenic fluid storage unit equipped with a cryogenic fluid transfer device that offers improved reliability.

[0008] To this end, the invention relates to a cryogenic fluid storage unit, the storage unit comprising:

[0009] - an internal reservoir, internally delimiting a fluid storage volume cryogenic; - an external tank, in which the internal tank is housed, the internal tank and the external tank being separated from each other by an intermediate low-pressure space; - a cryogenic fluid transfer unit housed in the intermediate space, the transfer unit comprising a body delimiting a chamber, a suction connection between the chamber and the cryogenic fluid storage volume, and a discharge connection between the chamber and an outlet cryogenic fluid out of the storage unit, a moving part configured to move relative to the body by varying the volume of the chamber, a motor, and a mechanical transmission transmitting motion from an output shaft of the motor to the moving part;

[0010] the moving part being linked to the body by a bellows isolating the motor and the mechanical transmission of the cryogenic fluid.

[0011] Because the moving part is connected to the body by a bellows that isolates the motor and the mechanical transmission from the cryogenic fluid, the motor and the mechanical transmission are not exposed to this cryogenic fluid. They are in contact with the vacuum prevailing in the intervening space. The bearings or bushings guiding the motor's output shaft, which are typically made of ceramic, do not seize when operating under vacuum. These bearings or bushings tend to seize in the presence of hydrogen, particularly when it is in gaseous form.

[0012] The storage unit may also have one or more of the following characteristics, considered individually or in all technically possible combinations:

[0013] - the body is directly attached to a flange fixed to the internal reservoir;

[0014] - the flange is fixed around an internal outlet orifice of the internal reservoir, provided at a low point in the internal reservoir;

[0015] - the body comprises a cylinder with a longitudinal central axis and a breech head closing a longitudinal end of the cylinder, the moving part being a piston moving in the chamber along the longitudinal direction without friction against the cylinder;

[0016] - the cryogenic fluid transfer organ comprises a rigidly fixed ring on an internal surface of the cylinder, the moving part having a head arranged longitudinally between the ring and the cylinder head, the bellows being compressible along the longitudinal direction and connecting the head of the moving part to the ring in a watertight manner;

[0017] - the movable organ comprises a longitudinal rod attached to the head, the organ of transfer comprising a guide ring for the rod in longitudinal translation, housed radially inside the bellows and rigidly fixed to the ring;

[0018] - the mechanical transmission includes an eccentric mounted on the output shaft of the engine and a connecting rod linking the eccentric to the rod;

[0019] - the suction includes at least one intake valve mounted on the cylinder head, and the the discharge system includes at least one exhaust valve mounted on the cylinder head;

[0020] - the discharge system includes at least one exhaust conduit provided in the body, at least one exhaust valve being interposed along at least one exhaust duct;

[0021] - the suction includes at least one intake passage provided through the cylinder head and opening directly into the internal outlet port, with at least one intake valve interposed along at least one intake passage.

[0022] According to a second aspect, the invention relates to a vehicle comprising an internal combustion engine having combustion chambers and a storage unit having the above characteristics, the transfer element pushing the cryogenic fluid into the combustion chambers of the thermal engine.

[0023] 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.1] The [Fig.1] is a sectional view of a cryogenic fluid storage unit according to the invention, taken in a vertical plane containing the central axis of the internal reservoir; - [Fig.2] The [Fig.2] is a front view of the storage unit of the [Fig.1], the bottom of the external tank being partially torn away to reveal the cryogenic fluid transfer organ; - [Fig.3] The [Fig.3] is a sectional view of part of the storage unit of figures 1 and 2, taken along the incidence of arrows III of the [Fig.2]. - [Fig.4] The [Fig.4] is a perspective view of the transfer organ of figures 1 to 3, part of the body and part of the bellows being torn away to reveal the moving part and the mechanical transmission; - [Fig.5] The [Fig.5] is a sectional view of the transfer element of the [Fig.4], taken in a plane containing the output shaft of the motor and the longitudinal direction of movement of the moving element; - [Fig. 6] Fig. 6 is a perspective view of the cylinder head of the transfer unit, with a cutout revealing an exhaust valve and an intake valve; and - [Fig.7] The [Fig.7] is a simplified schematic representation of a vehicle equipped with an internal combustion engine powered by the storage unit of figures 1 to 6.

[0024] The cryogenic fluid storage unit 1 shown in Figures 1 to 3 is intended to store a cryogenic fluid.

[0025] 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 1.

[0026] This fluid is typically hydrogen. Alternatively, the fluid is a natural gas such as methane (CH4), ammonia, or any other fluid suitable for an internal combustion engine. In another embodiment, the fluid is a cryogenic fluid such as helium, nitrogen, oxygen, or any other fluid suitable for industrial applications.

[0027] The storage unit 1 is typically intended to be carried on board a vehicle, for example a motor vehicle, a train, a boat or any other vehicle.

[0028] The motor vehicle is for example a car, a utility vehicle, a truck, etc.

[0029] The storage unit 1 is typically intended to power an internal combustion engine equipping a motor vehicle.

[0030] Alternatively, the storage unit 1 is intended to power a fuel cell. For example, the fuel cell is configured to produce electricity and electrically power an electric propulsion motor of the vehicle.

[0031] The cryogenic fluid storage unit 1 comprises an internal tank 3 internally delimiting a cryogenic fluid storage volume 5, an external tank 7 inside which the internal tank 3 is housed, the internal tank 3 and the external tank 7 being separated from each other by an intermediate space 9 maintained at low pressure.

[0032] A suspension 10 fixes the internal reservoir 3 to the external reservoir 7.

[0033] In the example shown, the internal reservoir 3 has a horizontal central axis C.

[0034] The internal reservoir 3 comprises a ferrule 11, closed at its two opposite axial ends by bottoms 13.

[0035] The ferrule 11 is cylindrical, centered on the central axis C.

[0036] The external reservoir 7 is also horizontally oriented.

[0037] It comprises a ferrule 15, closed at its two opposite axial ends by bottoms 17.

[0038] The ferrule 15 is cylindrical, centered on the central axis C.

[0039] Typically, the intermediate space 9 is maintained under a high vacuum.

[0040] This vacuum is typically on the order of 105 millibars, so as to strongly limit the heat transfer by convection from the external reservoir 7 to the internal reservoir 3.

[0041] Not shown, thermal insulation is interposed between the inner tank 3 and the outer tank 7. The thermal insulation is typically placed on the outer surface of the inner tank 3. The thermal insulation comprises, for example, a plurality of metal sheets superimposed on one another, with interposed layers of fibers.

[0042] The storage unit 1 further includes a transfer organ 19 for the cryogenic fluid, housed in the intermediate space 9.

[0043] The transfer unit 19 is configured to transfer the cryogenic fluid from the storage volume 5 to another piece of equipment, located outside the storage unit 1.

[0044] To this end, the storage unit 1 has a cryogenic fluid outlet 21. The cryogenic fluid outlet 21 is carried by the outer casing 7. It is fluidly connected to the equipment supplied by the transfer member 19.

[0045] This equipment is, for example, a heat exchanger intended to heat the cryogenic fluid, or is a valve, or is the vehicle's propulsion thermal engine, or is a fuel cell.

[0046] As can be seen more clearly in Figures 4 to 6, the cryogenic fluid transfer element 19 comprises a body 23 delimiting a chamber 25, a suction 27 connecting the chamber 25 with the cryogenic fluid storage volume 5, a discharge 29 connecting the chamber 25 with the cryogenic fluid outlet 21, a movable element 31 configured to move relative to the body 23 by varying the volume of the chamber 25, a motor 33, and a mechanical transmission 35 transmitting a movement from an output shaft 37 of the motor 33 to the movable element 31.

[0047] The transfer organ 19 is housed entirely in the intermediate space 9, no element of this transfer organ 19 penetrating the cryogenic fluid storage volume 5.

[0048] The body 23 is directly attached to a flange 39 fixed to the internal reservoir 3.

[0049] The flange 39 is fixed around an internal outlet 41 of the internal reservoir 3, located at a low point of the internal reservoir 3.

[0050] The internal outlet 41 is provided in one of the bottoms 13.

[0051] It is provided at a low point of the internal reservoir in the sense in which it is located, following the vertical direction, immediately above the lowest point of the cryogenic fluid storage volume 5.

[0052] In the example shown, the lowest point corresponds to the downward-facing generatrix of the ferrule 11. The internal outlet 41 is located immediately above said generatrix. The apex of the internal outlet 41 is situated, relative to said generatrix, at a height less than half the radius of the ferrule 11.

[0053] The external reservoir 7 has an access hatch 42 opposite the transfer element 19 ([Fig.3]).

[0054] This access hatch 42 is provided in one of the bottoms 17 of the external tank 7. It allows access to the transfer device 19, to carry out any maintenance operations.

[0055] The body 23 comprises a cylinder 43 with longitudinal central axis X, and a cylinder head 45 closing a longitudinal end of the cylinder 43.

[0056] The cylinder 43 is open at its longitudinal end opposite the cylinder head 45.

[0057] The cylinder 43 has, perpendicular to the longitudinal axis X, a circular internal section.

[0058] The moving part 31 is a piston moving in the chamber 25 along the longitudinal direction X, without friction against the cylinder 43.

[0059] In other words, the transfer unit 19 is of the piston pump type, which makes it possible to obtain high discharge pressures.

[0060] The moving part 31 is linked to the body 23 by a bellows 47 isolating the motor 33 and the mechanical transmission 35 from the cryogenic fluid.

[0061] In other words, the bellows 47 creates a watertight barrier between the chamber 25 on one side, and the motor 33 and the mechanical transmission 35 on the other side.

[0062] The bellows 47 is hermetically connected to the moving part 31. It is also hermetically connected to the body 23, and more specifically to the internal surface of the cylinder 43.

[0063] The bellows 47 allows the movable part 31 to move and vary the volume of the chamber 25, without compromising the sealing of the chamber 25.

[0064] The transfer member 19 comprises a ring 49 rigidly fixed on an internal surface 51 of the cylinder 43.

[0065] The moving part 31 has a head 53 arranged longitudinally between the ring 49 and the breech 45.

[0066] The head 53 has the shape of a plate having, perpendicular to the longitudinal axis X, an external section slightly smaller than the internal section of the cylinder 43.

[0067] The head 53 has a flat surface 55 facing the breech 45.

[0068] The bellows 47 is compressible along the longitudinal direction X.

[0069] The bellows 47 provides a sealed connection between the head 53 of the moving part 31 and ring 49.

[0070] As can be seen in figures 4 and 5, the bellows 47 has a general cylindrical shape and is coaxial with the longitudinal axis X. It is made of a metal sheet, stainless steel, typically 316L type stainless steel.

[0071] The bellows 47 has a general shape of corrugated tube, i.e. corrugated.

[0072] It includes internal corrugations 57 projecting inwards towards the bellows 47, and external corrugations 59 projecting outwards from the bellows 47. Each internal corrugation 57 is connected to two external corrugations 59, and conversely each external corrugation 59 is connected to two internal corrugations 57.

[0073] The internal corrugations 57 and the external corrugations 59 each extend along a closed contour around the longitudinal axis X.

[0074] Considered in section in a plane containing the longitudinal axis X, the wall of the bellows 47 has a sinuous shape.

[0075] A first longitudinal end 61 of the bellows 47 is rigidly fixed to the head 53 of the movable member 31. The first longitudinal end 61 is fixed in a sealed manner on the edge of the head 53, that is to say on the surface delimiting the head 53 in directions radially external with respect to the longitudinal axis X.

[0076] A second longitudinal end 63 of the bellows 47, opposite the first end 61, is rigidly fixed to the ring 49 in a watertight manner. The ring 49 is itself fixed in a watertight manner to the inner surface of the cylinder 43.

[0077] A seal is thus created between the second end 63 of the bellows 47 and the body 23.

[0078] Alternatively, the second end 63 of the bellows 47 is fixed in a sealed manner directly onto the internal surface of the cylinder 43.

[0079] The chamber 25 is thus delimited by the cylinder head 45, by the internal surface 51 of the cylinder 43, by the bellows 47 and by the head 53 of the moving part 31.

[0080] Its volume varies with the displacement of the mobile organ 31 along the longitudinal axis X.

[0081] The stroke of the moving part 31 defines the compressibility of the bellows 47.

[0082] To guarantee a very long service life for the bellows 47, it is sized for one billion compression / extension cycles.

[0083] According to one embodiment, this result is achieved by providing a 3 mm stroke for the compression of the bellows. 47 This requires a diameter of 100 mm, for example, taking into account the desired flow rate for the transfer element 19 and the rotational speed of the motor 33.

[0084] The height of the bellows 47 is for example 60 mm longitudinally, and the thickness of the metal sheet constituting the bellows 47 is 1.5 mm, the bellows 47 in this case being made up for example of 5 plies of 0.3 mm each.

[0085] The mobile organ 31 further comprises a longitudinal rod 65 attached to the head 53.

[0086] The rod 65 protrudes from the head 53 along the longitudinal axis X, in a direction opposite to the breech 45.

[0087] It extends along the central axis of the bellows 47 corresponding to the longitudinal axis X, and terminates with an end 67 located axially outside the bellows 47, but inside the cylinder 43.

[0088] Alternatively, the end 67 is located inside the bellows 47.

[0089] The transfer member 19 further includes a guide ring 69 for the rod 65 in longitudinal translation.

[0090] The ring 69 is housed inside the bellows 47.

[0091] The ring 69 is cylindrical and has a slightly larger internal cross-section that the external section of the rod 65.

[0092] The rod 65 is engaged in the ring 69 and is free to slide inside the ring 69.

[0093] The ring 69 is rigidly fixed to the ring 49.

[0094] To do this, legs 71 distributed around the longitudinal axis X rigidly connect the ring 69 to the ring 49.

[0095] The mechanical transmission 35 includes an eccentric 73 mounted on the output shaft 37 of the motor 33 and a connecting rod 75 connecting the eccentric 73 to the rod 65.

[0096] As can be seen in figures 4 and 5, the body 23 comprises a cylindrical housing 77, integral with the cylinder 43. The motor 33 is housed in the cylindrical housing 77.

[0097] The motor 33 is an electric motor, with a stator 79 and a rotor 81. The output shaft 37 of the motor 33 is fixed to the rotor 81. Alternatively, it is driven in rotation by the rotor 81 via a reduction gear not shown.

[0098] The output shaft 37 extends along a transverse axis Y, perpendicular to the longitudinal axis X.

[0099] The transverse axis Y intersects the longitudinal axis X.

[0100] The output shaft 37 is guided in rotation by two bearings 82.

[0101] The bearings 82 are preferably made of ceramic, which allows for a long service life.

[0102] The transfer member 19 comprises, as seen in [Fig.4], a support 83 rigidly fixed to the body 23, defining two flanges 85 parallel to each other.

[0103] The bearings 82 are housed in orifices provided in the flanges 85.

[0104] The support 83 is fixed to the end of the cylinder 43 opposite the cylinder head 45.

[0105] The eccentric 73 and the connecting rod 75 are arranged between the flanges 85.

[0106] The eccentric 73 is rigidly fixed to the output shaft 37.

[0107] The connecting rod 75 has a first end 86 having a circular slot 87 in which the eccentric 73 is housed. The opposite end 89 of the connecting rod 75 is rotationally connected to the end 67 of the rod 65. It is coupled to the end 67 by a rotating axis 91, extending parallel to the transverse axis Y.

[0108] The body 23 is rigidly fixed to the flange 39 via the cylinder head 45.

[0109] For this purpose, the cylinder head 45 has, opposite the chamber 25, a flat external face 93. The external face 93 is pressed against the flange 39.

[0110] The cylinder head 45 has orifices 95 provided to receive attachment elements to the flange 39, not shown in figures 4 and 5.

[0111] These orifices 95 are provided in ears of the cylinder head 45.

[0112] The outer face 93 also has a recessed groove 97, designed to receive A sealing gasket is not shown. The sealing gasket is pinched against the flange 39 when the body 23 is fixed to the flange 39.

[0113] The suction 27 includes at least one intake valve 99 mounted on the cylinder head 45.

[0114] The suction 27 includes at least one intake passage 101 provided through the cylinder head 45 and opening directly into the internal outlet orifice 41.

[0115] At least one inlet passage 101 leads directly into chamber 25.

[0116] At least one inlet valve 99 is interposed along at least one passage Admission 101.

[0117] In the example shown, the suction 27 has two inlet passages 101, with an inlet valve 99 interposed along each inlet passage 101.

[0118] Alternatively, the suction 27 includes a single inlet passage 101 and a single inlet valve 99, or three inlet passages 101 and three inlet valves 99, or even more than three inlet passages 101 and more than three inlet valves 99.

[0119] In any case, it is preferable to have the largest possible total passage area for the cryogenic fluid through the inlet passage(s) 101. Therefore, it is advantageous to have several inlet passages 101.

[0120] The number of intake passages 101 and the cross-section of each intake passage 101 depend on the internal diameter of the cylinder 43.

[0121] Each intake passage 101 has an upstream orifice 103 opening at the external face 93 of the cylinder head 45, and a downstream orifice 105 opening at the internal face 107 of the cylinder head 45.

[0122] The inner face 107 is flat. It is turned towards the chamber 25. It is opposite the outer face 93. It delimits the chamber 25.

[0123] Each intake passage 101 therefore passes through the cylinder head 45 in its entire thickness.

[0124] The passage or passages 101 are straight. This means that the inlet passage 101 has a straight central line C'. This central line C' is perpendicular to the outer face 93 and perpendicular to the inner face 107. It is parallel to the longitudinal axis X.

[0125] The intake valve or each intake valve 99 comprises a frame 108 rigidly fixed to the cylinder head 45. The frame 108 is arranged in the corresponding intake passage 101.

[0126] The inlet valve or each inlet valve 99 further includes a movable plate 109 that can be moved between a position of closing the inlet passage 101 and a position of clearing the inlet passage 101.

[0127] In the closed position, the movable plate 109 rests on a seat 111 formed in the cylinder head 45, at the level of the downstream orifice 105 of the intake passage 101. In the open position, the movable plate 109 is lifted away from the seat 111, towards the interior of the chamber 25.

[0128] The movable plate 109 carries a longitudinal axis 113, cooperating with a guide sleeve 115 formed in the frame 108. The longitudinal axis 113 and the sleeve of guide 115 guides the movement of the movable plate 109 longitudinally between its clearance position and its closing position.

[0129] At its end opposite the movable plate 109, the longitudinal axis 113 carries a foot 117. An elastic element 119 is interposed between the foot 117 and the chassis 108. The elastic element 119 is, for example, a helical compression spring.

[0130] The elastic organ 119 returns the movable plate 109 to the obturator position.

[0131] The discharge 29 includes at least one exhaust valve 121.

[0132] The discharge 29 also includes at least one exhaust conduit 123 provided in the body 23, at least one exhaust valve 121 being interposed along at least one exhaust conduit 123.

[0133] In the example shown, the discharge 29 has two exhaust conduits 123, an exhaust valve 121 being interposed along each exhaust conduit 123.

[0134] Alternatively, the discharge 29 comprises a single exhaust conduit 123 and a single exhaust valve 121, or three exhaust conduits 123 and three exhaust valves 121, or more than three exhaust conduits 123 and more than three exhaust valves 121.

[0135] The exhaust duct or duct 123 is provided in the body 23 in the sense that the exhaust duct 123 is provided in the material constituting the body 23.

[0136] Typically, the body 23 is made of cast iron, for example of type 316L stainless steel cast iron or aluminum cast iron.

[0137] The exhaust duct or ducts 123 are produced by the casting process. In other words, the exhaust duct or ducts 123 are cast. They are formed from a solid piece. They are not attached to the body 23.

[0138] Alternatively, the exhaust duct or ducts 123 are machined into the body 23.

[0139] The exhaust duct(s) 123 are fluidically connected to the cryogenic fluid outlet 21.

[0140] The exhaust valve or each exhaust valve 121 is housed in a housing 125 formed in the cylinder head 45. This housing 125 constitutes the upstream end of the corresponding exhaust duct 123.

[0141] This housing 125 is open at the level of the internal face 107 of the cylinder head 45 and closed at the level of the external face 93.

[0142] The exhaust valve 121 is designed in the same way as the intake valve 99. It has a frame 127, integral with the cylinder head 45. This frame 127 is housed in the housing 125.

[0143] The exhaust valve 121 further includes a movable plate 129 that can be moved between a position where the exhaust duct 123 is clear and a position where the exhaust duct 123 is closed. In the closed position, the plate mobile 129 is supported on a seat 131 formed in the chassis 127. The seat 131 is formed in a crown-shaped portion of the chassis 127, itself fixed in a sealed manner to the internal surface of the housing 125.

[0144] In the disengagement position, the movable plate 129 is raised away from the seat 131, longitudinally towards the external face 93 of the breech 45.

[0145] In other words, the movable plate 129 moves from the closing position to the clearing position along a longitudinal movement which moves it away from the inner face 107 of the breech 45 and towards the outer face 93 of the breech 45.

[0146] The movable plate 129 is integral with an axis 133 which projects longitudinally from the movable plate 129 towards the chamber 25.

[0147] The chassis 127 includes a ring 135 guiding the shaft 133 in longitudinal translation.

[0148] At its end opposite the movable plate 129, the axis 133 carries a foot 137. An elastic element 139 is interposed between the foot 137 and the frame 127. The elastic element 139 forces the movable plate 129 towards its closing position.

[0149] The elastic element 139 is typically a helical compression spring.

[0150] The operation of the transfer unit 19 will now be detailed.

[0151] The motor 33 drives the output shaft 37 in rotation.

[0152] The eccentric 73 rotates with the output shaft 37, inside the circular opening 87 provided in the head of the connecting rod 75. The connecting rod 75 converts the rotational movement of the output shaft 37 into a translational movement of the moving member 31. The latter moves longitudinally in an alternating motion, first away from the cylinder head 45 and then in the opposite direction, moving towards the cylinder head 45.

[0153] Under the effect of this alternating back and forth movement, the bellows 47 is alternately compressed and then stretched longitudinally.

[0154] When the movable member 31 descends, i.e. moves away from the cylinder head 45, the intake valve or valves 99 open under the effect of the pressure difference between the cryogenic fluid storage volume 5 and the chamber 25. This pressure difference is sufficient to overcome the restoring force of the elastic member 119. Conversely, the exhaust valve or valves 121 remain closed, the movable plate 129 being returned to its closed position by the elastic member 139 and by the pressure in the exhaust duct 123.

[0155] The cryogenic fluid can thus flow from the cryogenic fluid storage volume 5 into the chamber 25, through the inlet passage or each inlet passage 101.

[0156] When the moving part 31 moves upwards, i.e., approaches the cylinder head 45, the pressure inside the chamber 25 increases. This leads to the closure of the intake valve(s) 99. The moving plate 109 is displaced into its closed position by the pressure difference between the chamber 25 and the volume cryogenic fluid storage 5, and under the effect of the restoring force of the elastic element 119. Conversely, the exhaust valve or each one 121 opens, the movable plate 129 being moved into its clearance position under the effect of the pressure prevailing in the chamber 25. This pressure is sufficient to overcome the restoring force of the elastic element 139.

[0157] The cryogenic fluid is then expelled through the exhaust duct(s) 123.

[0158] Figure 7 illustrates a motor vehicle comprising an internal combustion engine internal 141 and a storage unit 1 as described above.

[0159] The internal combustion engine 141 is of the type adapted to operate using cryogenic fluid as fuel.

[0160] It includes combustion chambers 143. The transfer member 19 of the storage unit 1 pumps the cryogenic fluid into the combustion chambers 143 of the internal combustion engine 141.

[0161] To do this, the cryogenic fluid outlet 21 is fluidly connected to the combustion chambers 143 by a conduit 145.

[0162] The transfer member 19 is configured to discharge the cryogenic fluid at a pressure between 25 and 200 bars, preferably 40 and 120 bars, even more preferably 50 and 100 bars.

[0163] In the cryogenic fluid storage volume 5, the cryogenic fluid is stored at a pressure between 1 and 20 bars.

[0164] The transfer element 19 is therefore a high-pressure transfer element, allowing the pressure of the cryogenic fluid to be raised significantly, from the storage pressure in the cryogenic fluid storage volume 5 to the injection pressure in the combustion chambers 143.

[0165] The storage unit 1 described above has multiple advantages.

[0166] When the body of the transfer element is directly attached to a flange fixed to the internal tank, the storage unit is particularly compact.

[0167] When the flange is fixed around an internal outlet port of the inner tank, located at a low point in the inner tank, priming the transfer element is easy. Furthermore, it is possible to withdraw the cryogenic fluid even when the level of cryogenic fluid in the storage volume is low.

[0168] When the body comprises a cylinder with a central longitudinal axis and a cylinder head closing the longitudinal end of the cylinder, the moving part being a piston moving in the chamber along the longitudinal direction without friction against the cylinder, it is possible to obtain high discharge pressures. This is achieved without wear on the piston. The absence of leakage is guaranteed by the bellows.

[0169] When the transfer member comprises a ring rigidly fixed to the inner surface of the cylinder, the moving member having a longitudinally arranged head between the ring and the cylinder head, the bellows being compressible in the longitudinal direction and connecting the head of the moving part to the ring in a watertight manner, the arrangement of the bellows inside the cylinder is particularly compact and convenient.

[0170] When the moving member comprises a longitudinal rod fixed to the head, and the transfer member comprises a guide ring for the rod's longitudinal translation housed radially inside the bellows and rigidly fixed to the ring, the guidance of the moving member is achieved in a particularly simple and convenient manner. The transfer member is extremely compact because the guide is housed inside the bellows and the cylinder.

[0171] A mechanical transmission comprising an eccentric mounted on the output shaft of the motor and a connecting rod connecting the eccentric to the rod is well suited for moving the moving part.

[0172] When the intake has at least one inlet valve mounted on the cylinder head, and the discharge has at least one exhaust valve mounted on the cylinder head, the inlet and exhaust valves are arranged in a particularly simple and convenient manner in the transfer element. This contributes to the compactness of the transfer element.

[0173] When the discharge has at least one exhaust conduit provided in the body, with at least one exhaust valve interposed along at least one exhaust conduit, the size of the transfer element is reduced.

[0174] When the suction includes at least one intake passage provided through the cylinder head and opening directly into the internal outlet orifice, with at least one intake valve interposed along at least one intake passage, the pressure losses at the suction of the transfer element are minimized.

[0175] The storage unit may have multiple variants.

[0176] The internal reservoir and the external reservoir can be arranged in different orientations. They do not necessarily have horizontal axes, but can, for example, have vertical axes.

[0177] The mechanical transmission is not necessarily of the connecting rod and eccentric type. The mechanical transmission may be of the connecting rod and crank type, a linkage transmission, or any other suitable type of transmission.

[0178] The motor is not necessarily arranged as shown in the figures, with an output shaft at a right angle to the direction of movement of the moving part. The motor can be of any type suitable for moving the moving part.

Claims

Demands

1. Storage unit (1) for a cryogenic fluid, the storage unit (1) comprising: - an internal reservoir (3), internally delimiting a volume (5) for storing the cryogenic fluid; - an external reservoir (7), in which the internal reservoir (3) is housed, the internal reservoir (3) and the external reservoir (7) being separated from each other by an intermediate space (9) at low pressure;- a cryogenic fluid transfer element (19) housed in the intermediate space (9), the transfer element (19) comprising a body (23) delimiting a chamber (25), a suction (27) connecting the chamber (25) with the cryogenic fluid storage volume (5), a discharge (29) connecting the chamber (25) with a cryogenic fluid outlet (21) outside the storage unit (1), a movable element (31) configured to move relative to the body (23) by varying the volume of the chamber (25), a motor (33), and a mechanical transmission (35) transmitting motion from an output shaft (37) of the motor (33) to the movable element (31); the movable element (31) being connected to the body (23) by a bellows (47) isolating the motor (33) and the mechanical transmission (35) from the cryogenic fluid.

2. Storage unit (1) according to claim 1, wherein the body (23) is directly attached to a flange (39) fixed to the internal tank (3).

3. Storage unit (1) according to claim 2, wherein the flange (39) is fixed around an internal outlet orifice (41) of the internal tank (3), provided at a low point of the internal tank (3).

4. Storage unit (1) according to any one of claims 1 to 3, wherein the body (23) comprises a cylinder (43) with longitudinal central axis (X) and a cylinder head (45) closing a longitudinal end of the cylinder (43), the moving member (31) being a piston moving in the chamber (25) along the longitudinal direction (X) without friction against the cylinder (43).

5. A storage unit (1) according to claim 4, wherein the cryogenic fluid transfer element (19) comprises a ring (49) rigidly fixed to an internal surface (51) of the cylinder (43), the element mobile (31) having a head (53) arranged longitudinally between the ring (49) and the breech (45), the bellows (47) being compressible along the longitudinal direction and connecting the head (53) of the mobile member (31) to the ring (49) in a sealed manner.

6. Storage unit (1) according to claim 5, wherein the moving member (31) comprises a longitudinal rod (65) integral with the head (53), the transfer member (19) comprising a guide ring (69) for the rod (65) in longitudinal translation, housed radially inside the bellows (47) and rigidly fixed to the ring (49).

7. Storage unit (1) according to claim 6, wherein the mechanical transmission (35) comprises an eccentric (73) mounted on the output shaft (37) of the motor (33) and a connecting rod (75) connecting the eccentric (73) to the rod (65).

8. Storage unit (1) according to any one of claims 4 to 7, wherein the suction (27) comprises at least one inlet valve (99) mounted on the cylinder head (45), and the discharge (29) comprises at least one exhaust valve (121) mounted on the cylinder head (45).

9. Storage unit (1) according to claim 8, wherein the discharge (29) comprises at least one exhaust conduit (123) provided in the body (23), at least one exhaust valve (121) being interposed along at least one exhaust conduit (123).

10. Storage unit (1) according to claim 8 or 9 in combination with claim 3, wherein the suction (27) comprises at least one intake passage (101) provided through the cylinder head (45) and opening directly into the internal outlet port (41), at least one intake valve (99) being interposed along at least one intake passage (101).

11. Vehicle comprising an internal combustion engine (141) having combustion chambers (143) and a storage unit (1) according to any one of the preceding claims, the transfer member (19) expelling the cryogenic fluid into the combustion chambers (143) of the internal combustion engine (141).

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