valve for cryotechnical fluid

Abstract

A valve for cryogenic fluid and a supply circuit for cryogenic fluid, the valve comprising a control chamber (11), a first circulation chamber (12) communicating with the control chamber (11) via a control port (14), a second circulation chamber (13) communicating with the first circulation chamber (12) via a circulation port (15), forming a valve seat, a linear stroke actuator (20) housed in the control chamber (11) and configured to actuate a control stem (24) passing through the control port (14) and extending axially into the first circulation chamber (12), a shutter (25) movable between a closed and an open position, and a bellows (30), sealed but axially extendable, surrounding the control stem (24). Fig. 2

Description

Title of the invention: valve for cryogenic fluid Technical field

[0001] The present disclosure relates to a valve for cryogenic fluid and a circulation circuit for cryogenic fluid. Such a valve may in particular be used in a circulation circuit for liquid propellant of an engine, for example a hydrogen aircraft engine. Prior art

[0002] In order to drastically reduce the carbon footprint of commercial aircraft, hydrogen aircraft engine projects are currently being developed. However, the use of hydrogen in such an aircraft engine raises numerous technical implementation difficulties. In particular, this hydrogen is generally stored and distributed in the liquid state, and therefore at cryogenic temperatures, before possibly being reheated before its admission into the combustion chamber of the engine. However, although cryogenic propellant technology is well mastered for the space sector, it cannot be directly transposed to the aeronautics sector due to the specificities specific to this sector.

[0003] One of the difficulties encountered concerns the fuel supply circuit and, in particular, the pump of this supply circuit. Indeed, the pumps currently existing in the space sector are designed to provide relatively constant supply flow rates: thus, these pumps have a reduced number of operating points, which simplifies their design and allows very advanced optimization of the pump to the operating conditions. Conversely, an aircraft engine must be capable of operating in very different situations, with very different thrust regimes depending on the flight phase: taxi, takeoff, cruise, landing, etc.

[0004] Due to the very low temperatures, of the order of 20 K, and the very high pressures, of the order of 10 bars and even up to 70 bars, of the liquid hydrogen supplied by the engine supply circuit, the pump may be required to operate in unstable operating ranges when the flow rate passing through the pump is too low.

[0005] Another difficulty concerns the design of valves capable of operating at very low temperatures while controlling low flow rates. Indeed, the valves known to date in the aeronautical field are not designed to withstand the passage of a cryogenic fluid while the valves known to date in the space field are for their part sized to be crossed by much higher flow rates. important.

[0006] Finally, for an aeronautical application, the valve must be capable of ensuring a very large number of missions without degrading. Most valves in the space sector are designed to ensure only a single mission, and therefore could not ensure a satisfactory operating time for the aeronautical sector.

[0007] There is therefore a real need for a valve for cryogenic fluid and a circulation circuit for cryogenic fluid which are free, at least in part, from the drawbacks inherent in the aforementioned known configurations. Statement of the invention

[0008] The present disclosure relates to a valve for cryogenic fluid, comprising a control room, a first circulation chamber, communicating with the control chamber via a control orifice, and configured to be connected to a first cryogenic fluid line, a second circulation chamber, communicating with the first circulation chamber via a circulation orifice, forming a valve seat, and configured to be connected to a second cryogenic fluid line, a linear stroke actuator, housed in the control chamber and configured to actuate a control rod passing through the control orifice and extending axially in the first circulation chamber, a shutter, movable between a closed position, in which it is pressed against the valve seat, and an open position, in which it is at least partially at a distance from the valve seat, the valve being configured so that the position of the shutter is at least partly controlled by the position of the control rod, and a bellows, sealed while being axially stretchable, surrounding the control rod, a first end of the bellows being secured to a wall of the first circulation chamber, and a second end of the bellows being secured to the control rod.

[0009] The use of a linear stroke actuator allows fine adjustment of the flow rate of cryogenic fluid passing through the circulation orifice by acting finely on the valve shutter and therefore on the fluid passage section thus determined.

[0010] The use of a sealed bellows makes it possible to completely isolate the control chamber, in which the actuator is housed, from the circulation of cryogenic fluid. This then makes it possible to protect the actuator from direct contact with cryogenic fluid which could damage it. In addition, this bellows makes it possible to thermally decorrelate, at least in part, the control chamber and the cryogenic fluid chambers. culation, while allowing the transmission of the actuator control to the shutter. Indeed, the bellows can stretch axially to follow the movement of the control rod without breaking and without breaking the seal. It is then possible to maintain a warmer environment in the control chamber compared to the circulation chambers in order to use an actuator that could not otherwise operate at the temperature of the cryogenic fluid.

[0011] In the present disclosure, cryogenic fluid is understood to mean a fluid, preferably a liquid, whose temperature is less than 120 K, preferably less than 80 K, more preferably less than 30 K. The pressure of the cryogenic fluid may exceed 2 bars, preferably 10 bars or even 50 bars.

[0012] In certain embodiments, the cryogenic fluid is a liquid propellant, for example liquid hydrogen H2, liquid oxygen O2, liquid nitrogen N2, liquid helium He or liquid methane CH4.

[0013] In certain embodiments, the maximum flow rate of the valve is less than 100 g / s, preferably less than 50 g / s, more preferably less than 10 g / s.

[0014] In certain embodiments, the maximum hydraulic passage section of the valve is less than 25 mm2, preferably less than 10 mm2, more preferably less than 5 mm2.

[0015] In some embodiments, the control chamber is maintained under vacuum or in a neutral atmosphere. This makes it possible to maintain the actuator in a controlled atmosphere, conducive to the proper operation of the actuator. In particular, this can contribute to thermally insulating the actuator from the circulation chambers. When the chamber is maintained under vacuum, it is understood that the residual pressure in the chamber can be less than 30 mbar. When the chamber is maintained under a neutral atmosphere, it can be filled using helium He or nitrogen N2.

[0016] In some embodiments, the temperature in the control chamber is greater than 50 K, preferably greater than 150 K.

[0017] In certain embodiments, the actuator comprises a piezoelectric actuator. Such an actuator, the stroke of which is very short, makes it possible to ensure particularly fine adjustment of the position of the control rod and therefore of the position of the shutter. Such an actuator is thus particularly suitable for forming a valve offering fine adjustment of the flow rate. In addition, such an actuator benefits from significant stiffness, the passage section of the valve thus depends practically exclusively on the control voltage of the actuator. Open-loop control of the actuator can then be envisaged without significant risk of drift.

[0018] In some embodiments, the piezoelectric actuator is equipped with an am stroke amplifier, preferably of the pantograph type. Since the native stroke of a piezoelectric actuator is very short, such an amplifier makes it possible to amplify the movement of the actuator and therefore increase the maximum stroke of the control rod.

[0019] In certain embodiments, the maximum stroke of the actuator is less than 5 mm, preferably less than 1 mm, more preferably less than 0.5 mm. This maximum stroke is preferably measured after amplification when an amplifier is provided. The actuator is thus very precise and particularly suitable for a valve controlling low flow rates.

[0020] In some embodiments, the height of the control chamber, in the axial direction, is less than 10 cm, preferably less than 6 cm. The valve is thus particularly compact.

[0021] In some embodiments, the second circulation chamber is configured to constitute the upstream chamber of the valve while the first circulation chamber is configured to constitute the downstream chamber of the valve. In such a case, it is understood that the pressure is higher in the second circulation chamber than in the first circulation chamber. However, the reverse configuration is possible. In some configurations, the position of the upstream and downstream could also vary over time depending on the operation of the circuit on which the valve is installed. In particular, in the configurations according to the disclosure, when the shutter is fixed to the end of the control rod, the intrinsic dimensioning of the valve makes it insensitive to the pressure effects on the shutter compared to those generated by the actuator. This makes it possible to easily envisage reversing the upstream and downstream connections.

[0022] In certain embodiments, the circulation orifice is circular, preferably substantially centered on the axis of the control rod. This facilitates the centering of the shutter on its seat and promotes good sealing of the shutter in the closed position. The diameter of this orifice may in particular be of the order of 6 mm.

[0023] In some embodiments, the shutter is installed in the first circulation chamber or in the second circulation chamber. When the shutter is installed in the upstream circulation chamber, the pressure of the cryogenic fluid exerts a force on the shutter tending to close the valve. This promotes the centering of the shutter, when the latter is free, and promotes good sealing of the shutter in the closed position.

[0024] In some embodiments, the shutter is attached to the distal end of the control rod. The position of the shutter, and therefore the passage section, is thus directly determined by the position of the control rod and therefore by the actuator.

[0025] In certain embodiments, the shutter is separate from the control rod. In such a configuration, the shutter is provided in the upstream circulation chamber so that the pressure of the cryogenic fluid tends to press the shutter against the control rod: in this way, the position of the shutter, and therefore the passage section, remains determined by the position of the control rod. However, the shutter remains free to reposition itself and, in particular, to recenter itself on its seat in the closed position, even if the control rod is slightly off-center: this promotes good sealing of the shutter in its closed position.

[0026] In certain embodiments, the shutter is retained in a cage provided in the first circulation chamber or the second circulation chamber. Such a cage, perforated to allow the cryogenic fluid to pass through, makes it possible to prevent the shutter from making excessive excursions, even in the event of instability in the circulation of cryogenic fluid.

[0027] In some embodiments, the shutter is axisymmetric. This promotes centering and good sealing of the shutter.

[0028] In certain embodiments, the shutter has a portion whose section decreases in the axial direction, this portion preferably being a truncated cone or a truncated sphere.

[0029] In certain embodiments, the shutter is a ball, preferably spherical. The diameter of the ball may in particular be of the order of 8 mm.

[0030] In some embodiments, the shutter is a cylindrical sleeve, closed at least at one of its axial ends and the peripheral surface of which comprises at least one light. Such a cylindrical sleeve allows better control of the passage section of the valve as a function of the position of the control rod. In particular, it is possible to configure the geometry of said light to adjust the relationship determining the passage section as a function of the position of the cylindrical sleeve linked to the control rod.

[0031] In some embodiments, at least one lumen of the cylindrical socket is rectangular or triangular. A rectangular lumen results in a linear control law of the passage section as a function of the position of the control rod while a triangular lumen results in a non-linear control law.

[0032] In some embodiments, the actuator is configured to continuously adjust the position of the control rod so as to control the position of the shutter continuously between the closed position and a maximum open position. The valve can thus continuously and precisely adjust to any operating point between its two extreme positions.

[0033] In some embodiments, the actuator is configured to be controlled in open loop. This makes it possible to do without a position sensor in the valve.

[0034] In certain embodiments, the valve comprises a sensor configured to determine the position of the control rod. This may in particular be a position sensor taking, for example, the form of a Hall effect probe used in proximity measurement.

[0035] In some embodiments, the actuator is configured to be controlled in a closed loop. This ensures better precision of the valve control.

[0036] In some embodiments, the wall of the bellows is corrugated, the corrugations following one another in the axial direction. These corrugations provide the bellows with a certain elasticity in the axial direction. Preferably, these corrugations are axisymmetric.

[0037] In certain embodiments, the bellows has, at rest, a length greater than 15 mm, preferably greater than 20 mm. Preferably this length at rest does not exceed 50 mm.

[0038] In certain embodiments, the bellows has, at rest, a maximum external diameter of between 6 and 10 mm.

[0039] In some embodiments, the depth of the bellows corrugations is between 1 and 2 mm. By "depth of the corrugations" is meant here the difference between the diameter measured at the crests and the diameter measured at the troughs. Preferably, all the corrugations are identical.

[0040] In some embodiments, the bellows is hydroformed.

[0041] In some embodiments, the bellows is metallic, preferably steel. Such a metallic material is able to withstand the cryogenic temperatures of the cryogenic fluid.

[0042] In certain embodiments, the stiffness of the bellows, when faced with an axial extension force, is less than 30 N / mm.

[0043] In some embodiments, the first end of the bellows is secured, preferably welded, to the wall of the first circulation chamber surrounding the control orifice.

[0044] In some embodiments, the second end of the bellows is secured, preferably welded, to a flange extending radially from the control rod.

[0045] In certain embodiments, the first circulation chamber and the second circulation chamber are devoid of elastomer seals. Indeed, an elastomer seal could not withstand the temperature of the cryogenic fluid. On the other hand, polymer or metal / metal contact seals can be used.

[0046] The present disclosure also relates to a circulation circuit for cryogenic fluid, comprising a pump, comprising an inlet connected to an upstream line and an outlet connected to a downstream line, a recirculation line, extending from the downstream line to the upstream line, and a valve according to any one of the preceding embodiments, installed on the recirculation line so as to control the flow rate of the recirculation line.

[0047] Thanks to such a recirculation line, it is possible to control the pump with a minimum flow rate high enough to ensure stable operation of the pump and to redirect, when this minimum flow rate is higher than the desired circulation flow rate, a part of this flow rate upstream of the pump in order to obtain the circulation flow rate actually desired downstream of the circulation circuit. Thus, if the desired flow rate is lower than the minimum stability flow rate, the pump is driven at the minimum stability flow rate and the valve of the recirculation line is controlled to return to the upstream line the difference in flow rate between the minimum stability flow rate and the desired circulation flow rate; if the desired flow rate is higher than the minimum stability flow rate, the pump is driven to ensure said desired circulation flow rate and the valve is controlled to close to completely close the recirculation line.

[0048] A valve according to the present disclosure then makes it possible to accomplish this function of fine regulation of the recirculation line in cryotechnical conditions.

[0049] In certain embodiments, the circulation circuit is a supply circuit provided for supplying an engine with said cryogenic fluid, possibly after reheating the latter.

[0050] In some embodiments, the pump is a centrifugal pump, preferably a turbopump or a pump driven by an electric motor.

[0051] In the present disclosure, the terms "front" and "distal" are understood, along the direction of the control rod, on the side of the obturator; the terms "rear" and "proximal" are then understood on the side opposite the obturator.

[0052] The above-mentioned features and advantages, as well as others, will become apparent from reading the following detailed description of exemplary embodiments of the proposed valve and circulation circuit. This detailed description refers to the attached drawings. Brief description of the drawings

[0053] The attached drawings are schematic and are intended primarily to illustrate the principles of the disclosure.

[0054] In these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs.

[0055] [Fig-1] [Fig.l] represents an example of a circulation circuit.

[0056] [Fig.2] [Fig.2] represents an example of a valve, in an open state.

[0057] [Fig.3] [Fig.3] represents the valve of [Fig.2], in a closed state. Description of the embodiments

[0058] In order to make the disclosure more concrete, examples of circulation circuits and valves are described in detail below, with reference to the attached drawings. It is recalled that the invention is not limited to these examples.

[0059] [Fig.l] represents an example of a circulation circuit 1 for cryogenic fluid; more precisely, it is a liquid propellant supply circuit for an aircraft engine. The supply circuit 1 then comprises a propellant tank 2, a supply pump 3, of the centrifugal type, and a supply outlet 4, connected to the engine. An upstream line 3m connects the propellant tank 2 to the inlet of the supply pump 3; a downstream line 3v connects the outlet of the pump 3 to the supply outlet 4. In the present example, the tank 2 is a tank of liquid di-hydrogen H2, stored at approximately 20 K; the pressure downstream of the pump 3 is of the order of 10 bar.

[0060] The supply circuit 1 further comprises a recirculation line 5 connecting the downstream line 3v to the upstream line 3m bypassing the supply pump 3. A controllable valve 10 is positioned on this recirculation line 5.

[0061] [Fig.2] illustrates an example of such a controllable valve 10. This valve 10 comprises a control chamber 11, a first circulation chamber 12 and a second circulation chamber 13.

[0062] The first circulation chamber 12 extends from the control chamber 11, axially along a main axis A of the valve 10; a control orifice 14 is made, at the level of the main axis A, in the wall separating the first circulation chamber 12 from the control chamber 11.

[0063] The second circulation chamber 13 is provided in the extension of the first circulation chamber 12, in the axial direction; a circulation orifice 15 is made, at the level of the main axis A, in the wall separating the second circulation chamber 13 from the first circulation chamber 12. In the present example, the second circulation chamber 13 is the upstream chamber, thus connected to the downstream line 3v of the pump 3, and the first circulation chamber 12 is the downstream chamber, thus connected to the upstream line 3m of the pump 3.

[0064] An actuator 20, comprising a piezoelectric component 21 and an amplifier 22, is mounted in the control chamber 11. The piezoelectric component 21 extends in a direction orthogonal to the main axis A. The amplifier 22 takes the form of two pantographs 23, each mounted on an opposite face of the piezoelectric component 21. Each pantograph 23 thus comprises two elastic branches 23a, each fixed to an opposite end of the piezoelectric component 21 and joining at a central base 23b extending axially.

[0065] The piezoelectric component 21 has, at rest, a predetermined rest length; consequently, the actuator 20 has as a whole, at rest, a predetermined rest height, measured between the ends of the bases 23b of the two pantographs 23 of the amplifier 22. However, when an electrical voltage is applied to the piezoelectric component 21, the piezoelectric component 21 deforms so that its length increases; consequently, the branches 23a of the pantographs are moved apart, which brings the bases 23b closer to each other and therefore decreases the height of the actuator 20.

[0066] One of the bases 23b of the amplifier 22 is fixed in the control chamber 11 while the second base 23b is free to move. A control rod 24 is fixed to this second base 23b so as to extend axially along the main axis A: the control rod 24 thus extends through the control orifice 14 and along the first circulation chamber 12, substantially up to the circulation orifice 15.

[0067] A shutter 25, here taking the form of a spherical ball, is arranged in the second circulation chamber 13, just opposite the circulation orifice 15 which forms a seat for said shutter 25.

[0068] In this example, the shutter 25 is free, that is to say it is not fixed to the end of the control rod 24. The position of the shutter 25 is nevertheless constrained by the position of the control rod 24, the latter being able, depending on its position, to prevent the shutter 25 from being pressed against the circulation orifice 15. Furthermore, a cage 26, installed in the second circulation chamber 13 and in which the shutter 25 is housed, makes it possible to retain the shutter 25 radially.

[0069] Thus, when the actuator 20 is at rest, as shown in [Fig. 2], the actuator 20 has a maximum height Hmax, corresponding to its rest height; the control rod 24 is then in an advanced position in which it engages in the circulation orifice 15, thus pushing the shutter 25 back so as to prevent it from pressing against the circulation orifice 15. The valve 10 is thus in an open state in which propellant can pass from upstream to downstream of the second circulation chamber 13 to the first circulation chamber 12.

[0070] Conversely, as shown in [Fig. 3], when an electrical voltage is applied to the piezoelectric component 21, the height of the actuator 20 decreases until it reaches a minimum height Hmin, which retracts the control rod 24 into a retracted position in which it no longer hinders the movement of the shutter 25; the shutter 25, under the effect of the pressure of the fluid, centers itself and then presses against the circulation orifice 15. The valve 10 is thus in a closed state in which the circulation of the propellant between the second circulation chamber 13 and the first circulation chamber 12 is cut off.

[0071] Of course, by adjusting the voltage supplied to the actuator 20, it is possible to finely control the latter so as to precisely adjust its height and therefore the position of the control rod 24 and hence the position of the shutter 25, the latter being in fact normally returned against the end of the control rod 24 under the effect of the pressure forces of the fluid. It is thus possible to precisely and continuously adjust the passage section of the valve 10 between the two extreme states, fully open and closed, shown in Figures 2 and 3.

[0072] In the present example, the maximum height Hmax of the actuator is equal to 55.0 mm while its minimum height Hmin is equal to 54.5 mm.

[0073] The valve 10 further comprises a metal bellows 30, made here of stainless steel. The bellows 30, generally axisymmetric, comprises undulations succeeding one another in the axial direction. The rear end 31 of the bellows 30 is fixed to the wall of the first circulation chamber 12 so as to surround the control orifice 14. The front end 32 of the bellows is fixed to a radial flange 33 secured to the control rod 24.

[0074] The bellows 30 thus seals the control chamber 11, and therefore the actuator 20, from the circulation of propellant present in the first circulation chamber 21. Nevertheless, thanks to its undulations, the bellows has an elasticity which allows it to follow the movement of the control rod 24 without breaking.

[0075] In the present example, the bellows 30 has a stiffness equal to 27 N / mm and a length at rest equal to 20 mm; its maximum diameter, measured at the level of the crests of the corrugations, is equal to 8.5 mm.

[0076] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0077] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. Valve for cryogenic fluid, comprising a control chamber (11), a first circulation chamber (12), communicating with the control chamber (11) via a control orifice (14), and configured to be connected to a first cryogenic fluid line (3m), a second circulation chamber (13), communicating with the first circulation chamber (12) via a circulation orifice (15), forming a valve seat, and configured to be connected to a second cryogenic fluid line (3v), a linear stroke actuator (20), housed in the control chamber (11) and configured to actuate a control rod (24) passing through the control orifice (14) and extending axially in the first circulation chamber (12), a shutter (25), movable between a closed position, in which it is pressed against the valve seat (15), and an open position,in which it is at least partially spaced from the valve seat (15), the valve (10) being configured so that the position of the shutter (25) is at least partly controlled by the position of the control rod (24), and a bellows (30), sealed while being axially stretchable, surrounding the control rod (24), a first end (31) of the bellows (30) being secured to a wall of the first circulation chamber (12), and a second end (32) of the bellows (30) being secured to the control rod (24).,

2. A valve according to claim 1, wherein the control chamber (11) is maintained under vacuum or in a neutral atmosphere.

3. A valve according to claim 1 or 2, wherein the actuator (20) comprises a piezoelectric actuator (21).

4. Valve according to claim 3, wherein the piezoelectric actuator (21) is equipped with a stroke amplifier (22), preferably of the pantograph type.

5. A valve according to any one of claims 1 to 4, wherein the shutter (25) is attached to the distal end of the control rod (24).

6. A valve according to any one of claims 1 to 4, wherein the shutter (25) is separate from the control rod (24), and in which the shutter (25) is retained in a cage (26) provided in the first circulation chamber (12) or the second circulation chamber (13).

7. A valve according to any one of claims 1 to 6, wherein the actuator (20) is configured to continuously adjust the position of the control rod (24) so as to control the position of the shutter (25) continuously between the closed position and a maximum open position.

8. A valve according to any one of claims 1 to 7, wherein the wall of the bellows (30) is corrugated, the corrugations following one another in the axial direction.

9. A valve according to any one of claims 1 to 8, wherein the bellows (30) is metallic, preferably steel.

10. Valve according to any one of claims 1 to 9, in which the stiffness of the bellows (30), faced with an axial extension force, is less than 30 N / mm.

11. A valve according to any one of claims 1 to 10, wherein the first end (31) of the bellows (30) is fixed, preferably welded, to the wall of the first circulation chamber (12) surrounding the control orifice (14), and wherein the second end (32) of the bellows (30) is fixed, preferably welded, to a flange (33) extending radially from the control rod (24).

12. Circulation circuit for cryogenic fluid, comprising a pump (3), having an inlet connected to an upstream line (3m) and an outlet connected to a downstream line (3v), a recirculation line (5), extending from the downstream line (3v) to the upstream line (3m), and a valve (10) according to any one of the preceding claims, installed on the recirculation line (5) so as to control the flow rate of the recirculation line (5).

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