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); - a cryogenic fluid transfer element (19) housed in the intermediate space (9), between the internal tank (3) and the external tank (7), the transfer element (19) comprising a body (23) delimiting a chamber (25), a suction (27), a discharge (29) comprising at least one exhaust conduit (123) putting the chamber (25) into fluidic communication with an outlet (21) of cryogenic fluid 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 a motion from an output shaft (37) of the motor (33) to the movable element (31); at least one exhaust duct (123) being configured to cool the engine (33).Figure for the abridged version: 8.

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 allows the cryogenic fluid to be compressed.

[0005] For this purpose, it is possible to use piston pumps immersed in the hydrogen stored in the storage unit.

[0006] The heat released by the pump motor heats the cryogenic hydrogen, which reduces the possible storage time for the cryogenic hydrogen. This heat transfer reduces the dormancy time, that is, the storage time before the pressure in the storage unit reaches a maximum storage unit pressure and a release of gaseous hydrogen is necessary.

[0007] In this context, the invention aims to provide a cryogenic fluid storage unit that does not have the above defect.

[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 device housed in the intermediate space, the transfer device comprising a body delimiting a chamber, a suction connecting the chamber with the cryogenic fluid storage volume, a discharge including at least one exhaust conduit connecting the chamber with a cryogenic fluid outlet outside the storage unit, a movable part configured to move relative to the body by varying the volume of the chamber, a motor, and a mechanical transmission transmitting a movement from an output shaft of the motor to the movable part;

[0010] at least one exhaust duct being configured to cool the engine.

[0011] Because at least one exhaust duct is configured to cool the engine, the heat released by the engine does not contribute to heating the cryogenic fluid stored in the internal tank. This heat is transferred to the flow of cryogenic fluid expelled from the storage unit. It is removed with the cryogenic fluid.

[0012] This heat contributes to the warming of the outgoing cryogenic fluid stream, which is generally an advantage.

[0013] The storage unit may also have one or more of the following characteristics, considered individually or in all technically possible combinations:

[0014] - the motor is an electric motor comprising a rotor and a stator equipped of stator windings, at least one exhaust duct being configured to cool the stator windings;

[0015] - the transfer unit comprises a housing in which the motor is housed, at least an exhaust duct including a cooling section provided in the crankcase;

[0016] - the casing and the body came from matter;

[0017] - at least one exhaust duct comprises an intermediate section fluidly connecting the cooling section to the chamber, the intermediate section being provided in the body;

[0018] - the housing is tubular and has a central transverse axis, the section of cooling comprising a plurality of transverse portions parallel to the central axis, and a plurality of circumferential portions connecting the transverse portions together;

[0019] - the housing has a cylindrical part coaxial with the central axis and raised thicknesses protruding from an external surface of the cylindrical part, the cooling section being provided in the excess thickness;

[0020] - the casing is made of cast aluminum or cast steel;

[0021] - the body comprises flanges carrying bearings for guiding the rotation of the shaft engine output.

[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] The [Fig.6] is a perspective view of the cylinder head of the transfer unit, with a tear-out allowing an exhaust valve and an intake valve to be revealed; - [Fig.7] [Fig.8] Figures 7 and 8 are side views of the transfer unit, following the incidence of arrows VII and VIII respectively in [Fig.4], the exhaust ducts being shown as dashed lines; and - [Fig.9] The [Fig.9] is a simplified schematic representation of a vehicle equipped with an internal combustion engine powered by the storage unit of figures 1 to 8.

[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 ammonia, a natural gas such as methane (CH4), 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] Thermal insulation (not shown) 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 each other, 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 comprising at least one exhaust conduit 123 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 stroke of 3 mm for the compression of the bellows 47. This imposes 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 transfer unit 19 includes a housing 77, in which the motor 33 is housed.

[0097] The motor 33 is an electric motor, with a stator 79 and a rotor 81.

[0098] The output shaft 37 of the motor 33 is integral with the rotor 81. Alternatively, it is driven rotated by rotor 81 via a reduction gear not shown.

[0099] The output shaft 37 extends along a transverse axis Y perpendicular to the longitudinal axis X.

[0100] The transverse axis Y intersects the longitudinal axis X.

[0101] The output shaft 37 is guided in rotation by two bearings 82.

[0102] The bearings 82 are preferably made of ceramic, which allows for a long service life.

[0103] The body 23 comprises, as seen in [Fig.4], two flanges 85, carrying the bearings for the rotational guidance of the output shaft 37 of the motor 33.

[0104] The two flanges 85 are parallel to each other.

[0105] The bearings 82 are housed in orifices provided in the flanges 85.

[0106] The flanges 85 constitute a support 83 formed at the opposite end of the cylinder 43 to the cylinder head 45.

[0107] The eccentric 73 and the connecting rod 75 are arranged between the flanges 85.

[0108] The eccentric 73 is rigidly fixed to the output shaft 37.

[0109] 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.

[0110] The body 23 is rigidly fixed to the flange 39 via the cylinder head 45.

[0111] For this purpose, the breechblock 45 has, opposite the chamber 25, an external face 93 The outer face 93 is pressed against the flange 39.

[0112] The cylinder head 45 has orifices 95 provided to receive attachment elements to the flange 39, not shown in figures 4 and 5.

[0113] These orifices 95 are provided in ears of the cylinder head 45.

[0114] 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.

[0115] The suction 27 includes at least one intake valve 99 mounted on the cylinder head 45.

[0116] The suction 27 includes at least one intake passage 101 provided through the cylinder head 45 and opening directly into the internal 4L outlet

[0117] At least one inlet passage 101 leads directly into chamber 25.

[0118] At least one inlet valve 99 is interposed along at least one passage Admission 101.

[0119] In the example shown, the suction 27 has two inlet passages 101, with an inlet valve 99 interposed along each inlet passage 101.

[0120] Alternatively, the suction 27 comprises 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.

[0121] 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.

[0122] The number of intake passages 101 and the cross-section of each intake passage 101 depends on the internal diameter of the cylinder 43.

[0123] 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.

[0124] 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.

[0125] Each intake passage 101 therefore passes through the cylinder head 45 in its entire thickness.

[0126] 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.

[0127] The intake valve or valves 99 comprise a frame 108 rigidly fixed to the cylinder head 45. The frame 108 is arranged in the corresponding intake passage 101.

[0128] 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.

[0129] 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.

[0130] The movable plate 109 carries a longitudinal axis 113, cooperating with a guide sleeve 115 provided in the frame 108. The longitudinal axis 113 and the guide sleeve 115 guide the movement of the movable plate 109 longitudinally between its clearance position and its closing position.

[0131] 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.

[0132] The elastic element 119 recalls the movable plate 109 in the obturator position.

[0133] The discharge 29 includes at least one exhaust valve 121.

[0134] At least one exhaust valve 121 is interposed along at least one exhaust conduit 123.

[0135] In the example shown, the discharge 29 has two exhaust ducts 123. Alternatively, the discharge 29 has a single exhaust duct 123 or three exhaust ducts 123 or more than three exhaust ducts 123.

[0136] In any event, an exhaust valve 121 is interposed along each exhaust conduit 123.

[0137] The exhaust valve or valves 121 are housed in a housing 125 formed in the cylinder head 45. This housing 125 constitutes the upstream end of the corresponding exhaust duct 123.

[0138] 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.

[0139] 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.

[0140] The exhaust valve 121 further includes a movable plate 129 that can be moved between a position of clearance of the exhaust duct 123 and a position of closure of the exhaust duct 123. In the closure position, the movable plate 129 rests on a seat 131 formed in the frame 127. The seat 131 is formed in a ring-shaped portion of the frame 127, itself fixed in a sealed manner to the internal surface of the housing 125.

[0141] 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.

[0142] 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.

[0143] The movable plate 129 is integral with an axis 133 which projects longitudinally from the movable plate 129 towards the chamber 25.

[0144] The chassis 127 includes a ring 135 guiding the shaft 133 in longitudinal translation.

[0145] 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.

[0146] The elastic element 139 is typically a helical compression spring.

[0147] At least one exhaust duct 123 is configured to cool the engine 33.

[0148] More specifically, the stator 79 is equipped with stator windings 147, with at least one exhaust conduit 123 configured to cool the stator windings 147.

[0149] As can be seen in figures 4 and 5, the housing 77 is tubular and coaxial with the central transverse axis Y.

[0150] The stator 79 is annular, and coaxial with the central transverse axis Y.

[0151] The stator 79 has a sleeve 149 pressed against the internal surface 151 of the casing 77. The stator windings 147 are mounted on the sleeve 149, and are placed radially towards the inside of the sleeve 149.

[0152] The rotor 81 is cylindrical and extends along the central transverse axis Y. It is arranged inside the stator 79.

[0153] The housing 77 and the body 23 are made of material. They are typically cast.

[0154] The housing 77 and / or the body 23 is advantageously made of cast aluminum or cast steel, for example cast stainless steel type 316L.

[0155] At least one exhaust conduit 123 is configured so that the cryogenic fluid discharged by the transfer member 19 towards the cryogenic fluid outlet 21 flows in the or each exhaust conduit 123 in thermal contact with the stator windings 147.

[0156] At least one exhaust conduit 123 passes in the immediate vicinity of the stator 79.

[0157] More specifically, at least one exhaust conduit 123 includes a cooling section 153 provided in the casing 77.

[0158] The cooling section 153 is provided in the housing 77 in the sense that the cooling section 153 is provided in the material constituting the housing 77.

[0159] The cooling section 153 is produced by the casting process. In other words, the cooling section 153 is cast. It is formed from a solid piece. It is not attached to the housing 77.

[0160] Alternatively, the cooling section 153 is machined in the housing 77.

[0161] The at least one exhaust duct 123 includes an intermediate section 155 fluidly connecting the cooling section 153 to the chamber 25. The intermediate section 155 is provided in the body 23.

[0162] As described previously, the intermediate section 155 is formed in the material constituting the body 23. It typically comes from a foundry.

[0163] The at least one exhaust conduit 123 comprises at least one upstream section 157 fluidly connecting the intermediate section 155 to the chamber 25.

[0164] In the example shown, each exhaust duct 123 comprises its own upstream section 157. The intermediate section 155 and the cooling section 153 are common to the different exhaust ducts. The upstream sections 157 join and open into the intermediate section 155.

[0165] As can be seen in [Fig.8], the upstream sections 157 are provided in the cylinder head 45.

[0166] Each upstream section 157 comprises the housing 125 and a branch 159 opening into a lateral surface of the housing 125.

[0167] In the example shown, the branches 159 of the two upstream sections 157 form a Y-shaped fork, from which the intermediate section 155 originates.

[0168] The intermediate section 155 extends first into the cylinder head 45, then continues into the cylinder 43.

[0169] The cooling section 153, as seen in Figures 7 and 8, comprises a plurality of transverse portions 161 parallel to the central transverse axis Y, and a plurality of circumferential portions 163 connecting the transverse portions 161 together.

[0170] The transverse portions 161 are regularly spaced circumferentially around the central transverse axis Y. They each extend over most of the transverse length of the housing 77.

[0171] The circumferential portions 163 connect the end of a transverse portion 161 to the end of a neighboring transverse portion 161.

[0172] In the example shown, the cooling section 153 comprises three transverse portions 161 connected to each other by two circumferential portions 163. One of the transverse portions 161 is directly connected to the intermediate section 155. Another of the transverse portions 161 is connected to the cryogenic fluid outlet 21 by a conduit not shown.

[0173] As can be seen in figures 7 and 8, the housing 77 has a cylindrical part 165 coaxial with the central transverse axis Y and overthicknesses 167 projecting on an external surface 169 of the cylindrical part 165. The cooling section 153 is provided in the overthicknesses 167.

[0174] The overthicknesses 167 form ribs on the outer surface 169 of the cylindrical part 165. The ribs follow the shape of the cooling section 153.

[0175] Similarly, the body 23 also has a rib in which the intermediate section 155 is provided.

[0176] The operation of the transfer unit 19 will now be detailed.

[0177] The motor 33 drives the output shaft 37 in rotation.

[0178] 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.

[0179] Under the effect of this alternating back and forth movement, the bellows 47 is alternately compressed and then stretched longitudinally.

[0180] 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.

[0181] 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.

[0182] When the moving part 31 moves upward, 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 cryogenic fluid storage volume 5, and by the restoring force of the elastic part 119. Conversely, the exhaust valve(s) 121 opens, the moving plate 129 being displaced into its open position by the pressure in the chamber 25. This pressure is sufficient to overcome the restoring force of the elastic part 139.

[0183] The cryogenic fluid is then expelled through the exhaust duct(s) 123.

[0184] The cryogenic fluid circulates in the upstream sections 157, then in the section intermediate 155 up to the cooling section 153.

[0185] It travels through the cooling section 153 and cools the engine 33.

[0186] The cryogenic fluid passes through various transverse portions 161 distributed all around the engine 33, so that the latter is cooled over its entire periphery.

[0187] The cryogenic fluid circulates in the thickness of the wall of the casing 77 in such a way that the heat released by the stator windings 147 is transmitted by conduction to the cryogenic fluid.

[0188] After passing through the cooling section 153, the cryogenic fluid flows directly to the cryogenic fluid outlet 21, without passing back inside the cryogenic fluid storage volume 5.

[0189] Figure 7 illustrates a motor vehicle comprising an internal combustion engine 141 and a storage unit 1 as described above.

[0190] The internal combustion engine 141 is of the type adapted to operate using cryogenic fluid as fuel.

[0191] 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.

[0192] To do this, the cryogenic fluid outlet 21 is fluidly connected to the combustion chambers 143 by a conduit 145.

[0193] 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.

[0194] In the cryogenic fluid storage volume 5, the cryogenic fluid is stored at a pressure between 1 and 20 bars.

[0195] 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.

[0196] The storage unit 1 described above has multiple advantages.

[0197] When the motor is an electric motor comprising a rotor and a stator equipped with stator windings, with at least one exhaust duct configured to cool the stator windings, the motor is particularly well cooled. The stator windings do, in fact, give off a significant amount of heat.

[0198] When the transfer unit includes a housing in which the engine is housed, and at least one conduit comprising a cooling section provided in the housing, the cryogenic fluid circulates in the material constituting the housing. This contributes to the efficiency of engine cooling.

[0199] When the casing and the body are made of material, it is particularly easy to arrange the circulation of the cryogenic fluid.

[0200] The fact that at least one exhaust duct includes an intermediate section fluidly connecting the cooling section to the chamber, the intermediate section being provided in the body, contributes to facilitating the arrangement of the circulation of the cryogenic fluid.

[0201] The fact that the crankcase is tubular and has a transverse central axis, the cooling section comprising a plurality of transverse portions parallel to the central axis, and a plurality of circumferential portions connecting the transverse portions together, means that the crankcase is particularly well cooled. This contributes to the good cooling of the engine.

[0202] When the housing has a cylindrical part coaxial with the central axis and overthicknesses protruding on an external surface of the cylindrical part, the cooling section being provided in the overthicknesses, the arrangement of the cooling section in the material constituting the housing is facilitated.

[0203] When the casing is made of cast aluminum or cast steel, heat dissipation by diffusion is particularly good.

[0204] When the body includes flanges carrying bearings for rotating the motor output shaft, the heat released by the motor magnets can be dissipated by conduction along the motor output shaft, then through the bearings and flanges to the body of the transfer element. The latter is cooled by the circulation of the cryogenic fluid.

[0205] The storage unit may have multiple variants.

[0206] 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.

[0207] The mechanical transmission is not necessarily of the eccentric connecting rod type. The mechanical transmission may be of the crank-connecting rod type, a linkage transmission, or any other suitable type of transmission.

[0208] 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.

[0209] In a non-preferred embodiment, at least one exhaust duct is not formed in the material constituting the engine casing. It is attached to the casing and / or to the body of the transfer element.

[0210] The body and the casing can be two separate elements, fixed to each other, and not made of material from each other.

[0211] The cooling section can be designed differently from what has been described above. For example, it can wind helically around the central Y-axis, or adopt any other suitable shape. The cooling section can for example, comprising several branches arranged in parallel, served by a distribution manifold, and all opening into a discharge manifold connected to the cryogenic fluid outlet.

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) comprising at least one exhaust conduit (123) 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); at least one exhaust conduit (123) being configured to cool the motor (33).

2. Storage unit (1) according to claim 1, wherein the motor (33) is an electric motor comprising a rotor (81) and a stator (79) equipped with stator windings (147), at least one exhaust conduit (123) being configured to cool the stator windings (147).

3. Storage unit (1) according to claim 1 or 2, wherein the transfer member (19) comprises a casing (77) in which the motor (33) is housed, and at least one exhaust conduit (123) comprising a cooling section (153) provided in the casing (77).

4. Storage unit (1) according to claim 3, in which the casing (77) and the body (23) are made of material.

5. Storage unit (1) according to claim 4, wherein at least one exhaust conduit (123) comprises an intermediate section (155) fluidly connecting the section of cooling (153) in the chamber (25), the intermediate section (155) being provided in the body (23).

6. Storage unit (1) according to any one of claims 3 to 5, wherein the casing (77) is tubular and has a central transverse axis (Y), the cooling section (153) comprising a plurality of transverse portions (161) parallel to the central axis (Y), and a plurality of circumferential portions (163) connecting the transverse portions (161) to each other.

7. Storage unit (1) according to claim 6, in which the casing (77) has a cylindrical part (165) coaxial with the central axis (7) and overthicknesses (167) projecting on an outer surface (169) of the cylindrical part (165), the cooling section (153) being provided in the overthicknesses (167).

8. Storage unit (1) according to any one of claims 3 to 7, wherein the casing (77) is made of cast aluminum or cast steel.

9. Storage unit (1) according to any one of claims 3 to 8, wherein the body (23) comprises flanges (85) carrying bearings (82) for guiding the rotation of the output shaft (37) of the motor (33).

10. 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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