extraction valve

Abstract

Withdrawal valve (4) for a pressurized gas from a pressure gas storage tank (2), with 1.1 a pressure sleeve closed on one side (9); 1.2 a movable extraction piston (17) which, by its movement, opens or closes an extraction cross-section and which projects at least partially into the open side of the pressure sleeve (9); 1.3 an electromagnetic coil (12) which at least partially surrounds the pressure sleeve (9); 1.4 a movable armature (16) made of magnetizable material in the pressure sleeve (9); 1.5 a pilot bore (23) in the extraction piston (17) which connects the interior of the pressure sleeve (9) with an outflow opening (8) for the extracted gas; 1.6 a sealing element (24) which is pressed against the pilot bore (23) by a spring element (26) to seal; 1.7 a functional connection between the sealing element (24) and the anchor (16), such that when the anchor (16) moves, the sealing element releases the pilot bore; 1.8 The extraction piston (17) is at least partially made of magnetizable or permanent magnetic material (22) on its side facing the armature (16); characterized in that 1.9 the extraction piston (17) is sealed against the pressure sleeve (9) by means of a seal (36); and that 1.10 a bypass bore (35) is arranged in the extraction piston (17), which runs between the side of the extraction piston (17) facing the area connected to the pressure gas storage tank (2) and the side of the extraction piston (17) facing the interior of the pressure sleeve (9); and wherein a throttling point (38) is arranged in the bypass bore (35); and a needle (41) projecting towards the extraction piston (17) is arranged in a base body (34), which interacts with the throttling point (38) in such a way that a different diameter is released in the area of ​​the throttling point (38) depending on the position of the extraction piston (17).

Description

[0001] The invention relates to a withdrawal valve for pressurized gas from a pressurized gas storage tank according to the preamble of claim 1. The invention also relates to the use of such a withdrawal valve.

[0002] Withdrawal valves for pressurized gases from a compressed gas storage tank, particularly for compressed natural gas or compressed hydrogen, which are typically stored at nominal pressures of 260 bar or 700 bar, are known per se from the prior art. A withdrawal valve according to the invention allows not only the withdrawal of gas but also its addition to the compressed gas storage tank. Typically, the design is a so-called pilot valve, in which the pressure of the gas in a pressure sleeve, which has further actuating elements of the withdrawal valve, is used to assist in opening or closing the withdrawal valve or a withdrawal piston of the valve that controls the withdrawal cross-section, via a set ratio of pilot / bypass or control bores. Reference is made in particular to JP S60-21070U; CN 202215826U; DE 32 44 840 A1 and EP 1 694 994 B1 are referenced.

[0003] An exemplary extraction valve is described in particular in EP 1 682 801 B1. The problem with the design described therein lies primarily in the fact that the extraction piston is supposed to be held in its open position by a pressure differential. This differential is created when the gas intended for extraction spreads from one side of the extraction piston to the other via seals, labyrinths, and gaps. A sufficient pressure differential must be generated to ensure functionality. This pressure differential then holds the extraction piston in the open position. In practice, however, it has been found that the gaps, labyrinths, and seals do not provide a sufficient pressure differential to guarantee the desired functionality.While this is theoretically possible, it requires a very detailed design of the seals based on numerous experimental investigations to provide the necessary pressure differential. Therefore, exceptionally high manufacturing tolerances must be maintained in the area of ​​the seals. However, the actuation process then leads to wear, so that after a short service life the desired conditions can no longer be maintained, and the problem arises again that the extraction piston closes unintentionally in certain situations. Although it can then be reopened by electromagnetic forces, this results in a "fluttering" of the extraction piston, which leads to a highly intermittent extraction flow and increased noise emissions.Furthermore, the fluttering causes enormous wear and tear within the electromagnetic extraction valve, thus adversely affecting its service life.

[0004] The object of the present invention is to improve the described extraction valve.

[0005] According to the invention, this problem is solved by the features in the characterizing part of claim 1. Advantageous embodiments and further developments are described in the dependent claims. Claim 11 also specifies a particularly preferred use of the dispensing valve.

[0006] The extraction valve according to the invention provides a movable extraction piston which, by its movement, opens or closes an extraction cross-section. It is formed on the open side of a pressure sleeve, projecting at least partially into it. Furthermore, an electromagnetic coil is arranged around the pressure sleeve. A movable armature, made of a magnetizable material, is positioned within the pressure sleeve and can be moved accordingly when the coil is energized. Analogous to the prior art, the extraction piston has a pilot bore that connects the interior of the pressure sleeve to an outlet for the extracted gas. A sealing element is pressed against the pilot bore by a spring element, and, via an operative connection between the sealing element and the armature, can open the pilot bore when the armature moves.According to the invention, the extraction piston is designed such that, on its side facing the armature, it is at least partially made of magnetizable or permanent magnetic material. This design of the extraction piston, at least on its side facing the armature, ensures that when the armature is open and penetrated by magnetic field lines, a portion of these field lines passes through the magnetizable material or interacts with the permanent magnetic material. As a result, when the coil is energized and the armature is in the open position, the extraction piston is drawn towards the armature by magnetic forces and held in this position. This reliably prevents the pilot bore from being unintentionally closed by the sealing element interacting with the armature as long as the coil is energized.This results in very simple and safe functionality.

[0007] In the embodiment of the withdrawal valve according to the invention, a seal is further provided between the withdrawal piston and the pressure sleeve. This seal allows movement of the withdrawal piston as described while still ensuring a reliable seal between the pressure sleeve and the withdrawal piston. Since the propagation of pressure within the pressure sleeve is important for functionality, the inventive design also incorporates a bypass bore in the withdrawal piston. This bypass bore connects the area of ​​the withdrawal piston connected to the pressure reservoir with the area of ​​the withdrawal piston facing the interior of the pressure sleeve. This bypass bore allows for pressure equalization, ensuring that, when the withdrawal piston is in the closed position, the pressure sleeve is pressurized by the pressure in the pressurized gas reservoir, at least after a certain period of time.Depending on the desired functionality, it makes sense to throttle or influence the gas flow through the bypass bore accordingly.

[0008] According to an advantageous embodiment of the invention, a throttling point can therefore be arranged in the bypass bore. Such a throttling point can be realized by a corresponding bore diameter of the bypass bore. In a particularly favorable and advantageous embodiment of this idea, the throttling point can also be realized in the form of a throttling bushing inserted, in particular pressed into, the bypass bore. The bypass bore can then be realized relatively easily with a larger diameter, for example, a diameter in the range of one millimeter or a few millimeters. Subsequently, a bushing corresponding to this diameter is pressed in, which in turn has the diameter intended for throttling, for example, a bore on the order of 50–150 µm.

[0009] According to an advantageous further development of the idea, the throttling point has a smaller diameter than the pilot bore. This design ensures that the withdrawal valve always opens reliably. When the pilot bore opens, the pressure inside the pressure sleeve flows towards the outlet for the withdrawn gas. Since the diameter of the pilot bore is larger than the diameter of the throttling point, the gas flows from the pressure accumulator area through the throttling point more slowly than it flows out through the pilot bore. This design facilitates the movement of the withdrawal piston into the open position.

[0010] Ideally, the size difference between the bores would be as large as possible. However, this would be disadvantageous when closing the extraction valve, i.e., when the extraction piston moves in the opposite direction. Therefore, in practice, a compromise is chosen in which the throttling point has a diameter on the order of one-third to one-half the diameter of the pilot bore.

[0011] According to the invention, a needle projecting towards the dispensing piston is arranged in a base body fixedly mounted below the dispensing piston opposite the pressure sleeve. This needle interacts with the throttling point in such a way that a different diameter of the throttling point is exposed depending on the position of the dispensing piston. Ideally, such a needle interacts with the corresponding opening of the throttling point such that, for example, in the lower position of the dispensing piston (i.e., in the closed position), a very small cross-section is exposed between the needle and the throttling point. This produces the aforementioned effect, which advantageously facilitates the opening of the dispensing valve.

[0012] The upward movement of the extraction piston then opens a larger cross-section, ideally one that is even larger than the diameter of the pilot bore. In this case, closing is also ideally supported, as the larger diameter allows gas to flow into the pressure sleeve faster than it can flow out through the pilot bore. With the magnetic force deactivated, the movement of the extraction piston thus achieves a very fast and reliable closure of the extraction valve.

[0013] The needle can advantageously be designed such that it is pre-tensioned against the extraction piston by a spring element and its travel towards the piston is limited by a stop. Such a design enables safe and reliable functionality with minimal manufacturing tolerances. The needle can, in particular, be designed with a conical end facing the extraction piston. It can then engage a corresponding metallic counterpart in the throttle. In the lower, i.e., closed, position of the extraction piston, the force of the spring can then press the needle against this surface, so that only a relatively small flow cross-section remains open, or, by pressing the elements together, no or almost no cross-section remains open. This ideally assists the opening of the extraction piston.When the extraction piston moves to its upper position, the needle continues to move a short distance before reaching its stop. This allows for a comparatively large flow cross-section between the needle and the restrictor point when the extraction piston stroke exceeds the needle's maximum permissible stroke. This creates a cross-section larger than that of the pilot bore, thus optimally supporting the closing process.

[0014] In a further, highly advantageous embodiment of this idea, a sealing surface, particularly a metallic one, can be formed between the needle and the extraction piston. This sealing surface engages when the extraction piston is in its closed position, facing away from the interior of the pressure sleeve. Ideally, the sealing surface is designed as a radial sealing surface, as this allows for simple manufacturing with acceptable tolerances.

[0015] Particularly in the latter case, but in principle always, it can be designed so that the needle does not taper to a conical point at its tip, but rather narrows accordingly due to at least two, and especially three, attached surfaces. This allows a large cross-section to be exposed relatively quickly with a short stroke, and the needle is mechanically more robust compared to a needle that tapers conically over a comparatively long distance and is very pointed.

[0016] In a further highly advantageous embodiment of the extraction valve according to the invention, a guide pin can also be arranged in the base body, which interacts with a guide bore in the extraction piston in such a way that the extraction piston cannot rotate about its longitudinal axis. This is particularly advantageous when using a needle, but can also be used in a design without a needle. The anti-rotation device provided by the guide pin ensures, on the one hand, that the needle is not damaged, as it can precisely target the area into which it is intended to penetrate. In both cases, and when a needle is not desired, it is also ensured that the sealing surfaces between the pressurized gas reservoir and the discharge opening, which are located in the base body on the one hand and in the extraction piston on the other, do not rotate relative to each other during operation.Over time, the surfaces between the seal and the sealing surface, which adapt to each other, always remain in the same facing position. This achieves a significant improvement in the sealing of the extraction valve, particularly in the area of ​​its main seal between the pressurized gas reservoir and the extraction port, using simple means.

[0017] As already mentioned, the extraction valve can be used particularly at high pressures, for example, for compressed natural gas, which is typically stored at nominal pressures on the order of 260 bar, or for hydrogen, which is currently stored particularly at nominal pressures of 700 bar. Especially at such high pressures, the extraction valve provides very safe and reliable functionality with a very simple design. The preferred use of the extraction valve according to the invention is therefore for extracting gas as fuel for a vehicle from a pressurized gas storage tank in which the gas is stored at a nominal pressure of more than 250 bar, particularly more than 650 bar. The vehicle can then be powered by the extracted gas, for example, via an internal combustion engine.Particularly when storing hydrogen, as an alternative to such propulsion by burning the hydrogen, the use of hydrogen in a fuel cell or fuel cell system can be provided, which then supplies electrical drive power for the vehicle.

[0018] Further favorable embodiments and advantageous developments of the extraction valve according to the invention result from the exemplary embodiments which are described in more detail below with reference to the figures.

[0019] This shows: Fig. 1 a vehicle indicated in principle; Fig. 2 a basic sectional view through the structure of a withdrawal valve; Fig. 3 a section showing the extraction piston analogous to the illustration in Fig. 2 in a first possible embodiment according to the invention; Fig. 4 a section showing the extraction piston analogous to the illustration in Fig. 2 in a second possible embodiment according to the invention; Fig. 5 a section showing the extraction piston analogous to the illustration in Fig. 2 in a third possible embodiment according to the invention; Fig. 6 a section showing the extraction piston analogous to the illustration in Fig. 2 in a fourth possible embodiment according to the invention in a first position of the extraction piston; Fig. 7 a representation analogous to Fig. 6 in a second position of the extraction piston; and Fig. 8 a section showing the extraction piston analogous to the illustration in Fig. 2 in a fifth possible embodiment according to the invention.

[0020] In the presentation of the Fig. Figure 1 shows a vehicle 1 in principle. A compressed gas storage tank 2 is depicted within the vehicle 1, which can be part of a storage system for, for example, compressed natural gas or hydrogen. The compressed gas storage tank, or, if there are several, each of the compressed gas storage tanks, has a valve 3, typically an on-tank valve (OTV). Part of this valve 3 is a withdrawal valve 4 for the gas stored under pressure in the compressed gas storage tank 2. This is shown in the illustration of the Fig. 1 is not explicitly recognizable, but this will be discussed in more detail later. The extracted gas flows to an energy converter 5, which can be designed, for example, as an internal combustion engine or a fuel cell. It uses the energy stored in the gas to provide mechanical energy, for example, via combustion in a reciprocating engine, or to generate electrical energy from the gas and oxygen from the ambient air, for example, in a fuel cell. This energy flow to one of the wheels 7 is illustrated by a dashed arrow labeled 6, purely as an example. Ultimately, the gas stored in the compressed gas storage tank 2 serves to provide drive energy for the vehicle 1.

[0021] The extraction valve 4 itself, which, for example, can be arranged in the valve 3 analogously to the aforementioned prior art, is shown in the illustration of the Fig. 2 in a first possible embodiment is shown in a schematic sectional view. The withdrawal valve 4 comprises a pressure sleeve 9, which can be made of a non-magnetizable material, for example 1.4435 or SUSF316L. This so-called pressure sleeve is closed at one end and, at its other end, is sealed by a gasket in the embodiment shown here, is connected to an annular space 10, which is connected to the interior of the pressurized gas reservoir 2 via a line 11 (indicated by dashed lines). Through gaps between the inner wall of the pressure sleeve 9 and the components installed therein, the pressure will have spread throughout the entire pressure sleeve 9, at least after some time. The pressure sleeve 9 is then surrounded by a coil 12, indicated on one side of the pressure sleeve 9.The coil 12 also has a magnetizable coil yoke 13, which has a break 14 in a central region with respect to the axial length of the pressure sleeve 9. The coil 12 and the coil yoke 13 with the break 14 are preferably rotationally or mirror-symmetrically designed and arranged around the rotationally symmetrically designed pressure sleeve 9.

[0022] In the pressure sleeve 9, the illustration shows the Fig. 2. From top to bottom, i.e., from the closed end of the pressure sleeve 9 to the open end of the pressure sleeve 9, a core 15, made of magnetizable material, for example 1.4016IM, is arranged first. Adjoining this core 15, which is pressed into the pressure sleeve 9, is an armature 16, which may, for example, be made of the same material. Following the armature 16 is a withdrawal piston 17, which in the embodiment shown here is made of several parts. In this embodiment, it includes a sealing device 18, which, together with a counter element 19, in this case a flat surface on a base body 34, seals the annular space 10, which is connected to the interior of the pressurized gas storage tank 2, against a central withdrawal opening 20, which is indirectly connected to the energy converter unit.The extraction piston 17 also comprises a screwed-in central element 21 and, on its side facing the armature 16, a ring 22, which is designed, for example, as a permanent magnet, but in particular made of a magnetizable material, for example, the same material as the armature 16 and the core 15. In this embodiment, the remainder of the extraction piston 17, with the exception of the seals 18, can then be made, for example, of a non-magnetizable material, for example, the material of the pressure sleeve 9. In the area of ​​the extraction piston 17 facing the closed end of the pressure sleeve 9, a pilot bore 23 is also visible, which is typically designed as a bore with a very small diameter, for example, a diameter of a few tens to a few hundred micrometers. It is connected to an outflow opening 8 in the central element 21. This pilot bore 23 is located in the area shown in the diagram. Fig. 2 shown closed state of the withdrawal valve 4 via a sealing element 24 which is supported by a rod 25 which extends through the armature 16 and the core 15, and a spring element 26 at the closed end of the pressure sleeve 9.

[0023] In the presentation of the Fig. Figure 2 shows the closed state of the dispensing valve 4, in which the dispensing piston 17 is positioned to seal the annular space 10 against the dispensing opening 20. When the coil 11 is energized, a magnetic flux is generated, particularly in the yoke 13. However, due to the gap 14 in the yoke 13, the magnetic field lines cannot form a closed magnetic circuit. They therefore travel through the non-magnetizable material of the pressure sleeve 9 into the material of the core 15. This is illustrated by several dotted lines. They then attempt to overcome an air gap 27 between the core 15 and the armature 16 in order to return to the yoke via the armature 16. Since the air gap 27 is smaller than the gap 14, the path shown for the magnetic field lines is the preferred one.To ensure maximum magnetic flux, it is advantageous to close the air gap 27. The magnetic forces therefore move the armature 16, supported by the sealing element 24 and the rod 25, against the force of the spring element 26 towards the core 15, thereby closing the air gap 27. The air gap 27, which typically has a width of less than 0.7 mm in the open state, is closed to zero, so that the armature 16 rests directly against the core 15. This promotes the preferred maximum possible magnetic flux.

[0024] The arrangement via the sealing element 24, which interacts with the armature 16, ensures that, on the one hand, the force of the spring element 26 must be overcome when the armature moves. On the other hand, the movement of the armature 16 causes the pilot bore 23 to open, as the sealing element 24 lifts away from it. As already mentioned, the pressure inside the pressure sleeve 9 is typically the same as in the pressurized gas storage tank, for example, approximately 700 bar nominal pressure when storing hydrogen. Since there is no pressure or a much lower pressure in the extraction port 20, which leads to the energy converter 5, the gas contained in the pressure sleeve 9 flows out after the pilot bore 23 opens, via a central exhaust port 27 in the armature 16 and the corresponding extraction port 20.The pressure in the region of the annular space 10 can be the same as, or much higher than, that in the region of the pressure sleeve 9 above the extraction piston 17. If a pressure difference exists, this can, in addition to the magnetic force, cause the extraction piston 17 to move out of the space. Fig. The upward position shown in Figure 2 is favored. At equal pressures, i.e., a differential pressure of zero, the extraction piston is opened or held open solely by magnetic force. Switching at maximum differential pressure is prevented, in particular, by the fact that pressure equalization occurs exclusively through the actively switched pilot bore 23.

[0025] To ensure that the extraction piston 17 remains securely and reliably in its open position, the aforementioned ring 22, made of magnetizable material, is arranged on the side of the extraction piston 17 facing the armature 16. This design ensures that, at least when the extraction piston 17 has moved towards the closed end of the pressure sleeve 9 until its shoulder 28 abuts the counter stop 29, a portion of the magnetic field lines also passes through the ring 22, thus securely holding the extraction piston 17 in the vicinity of the armature 16 as long as the coil 12 is energized.The design of the extraction piston 17 and in particular the distance between the side of the ring 22 facing the anchor 16 and the shoulder 28 is designed such that an air gap 30 between the ring 22 and the anchor 16 does not close down to zero, but always leaves a minimal air gap in order to release a defined cross-section between the extraction opening 20 and the annular space 10 via the stop of the shoulder 28 on the counter stop 29.

[0026] To actuate the valve, i.e., to open it, the coil 12 is energized accordingly. Typically, a slightly higher current is required until the armature 16 breaks free. To hold it in place, the current can then be reduced. The state just described then occurs. If the extraction valve 4 is to be closed again, the coil 12 is de-energized. The armature 16 and the extraction piston 17 then fall apart via its ring 22 made of magnetic material, whereby the force of the spring element 26 closes the pilot bore 23 via the sealing element 24. This results in the same pressure being established in the area of ​​the pressure sleeve 9 as in the area of ​​the extraction opening 20, so that, due to the force of the spring element 26, the closed valve 4 is once again closed. Fig. 2 sets the depicted state.

[0027] In the presentation of the Fig. In the edge region of the air gap 27 between the anchor 16 and the core 15, a projection 31 of the core 15 and a corresponding recessed area 32 of the anchor 16 are now visible. This is collectively referred to as a cone and is designated with the reference numeral 33. Such a cone 33 enables a maximization of the attractive force between the anchor 16 and the core 15 at a defined distance.

[0028] As mentioned, in this design, it is necessary that the pressure spreads accordingly within the pressure sleeve 9 through the gap space between the extraction piston 17 and the pressure sleeve 9, which is always required due to the movable extraction piston 17. This can lead to a somewhat inaccurate operating principle, as the gap dimensions, especially in relation to the pilot bore 23, are not always exactly as desired.

[0029] To remedy this, further education, which is part of the Fig. 3 ff. is schematically represented in section 3; it is now provided that the extraction piston 17, as shown for example in the illustration of the Fig. As indicated in Figure 3, a bypass bore 35 is provided between the annular space 10 and the opposite side of the extraction piston 17. Simultaneously, a seal 36 is provided between the extraction piston 17 and the pressure sleeve 9, parallel to the bypass bore 35, which prevents gas from passing through the gap between the pressure sleeve 9 and the extraction piston 17. Thus, the bypass bore 35 allows controlled gas flow from the annular space 10 into the interior of the pressure sleeve 9.

[0030] Preferably, the bypass bore 35 has a smaller diameter than the pilot bore 23 to facilitate the opening of the extraction valve 4. Ideally, the design is such that the pilot bore 23 has a diameter at least twice that of the bypass bore 35. With a pilot bore diameter of 150–250 µm, this would correspond to a bore diameter for the bypass bore 35 in the range of 75–125 µm. Achieving this over the entire length of the bypass bore 35 is very difficult, so according to an advantageous design... Fig. As shown in Figure 4, a further development may be provided for in which a throttle bushing 37 is inserted into the bypass bore 35, which, in one of the illustrated embodiments, widens accordingly at its lower end. This throttle bushing 37 can, for example, be screwed in, glued in, or otherwise inserted. Ideally, it is connected to the material of the extraction piston 17 by pressing it into the bypass bore 35. A throttle point, designated in the illustration as a small bore with reference numeral 38, can then be very easily realized in the throttle bushing 37 itself. The diameter of this throttle point 38 can be manufactured very precisely independently of the extraction piston and then integrated into the extraction piston 17 via an interference fit.

[0031] In the presentation of the Fig. 5 is an alternative embodiment analogous to the representation in Fig. 3 to recognize. Of course, it can also be used with the in Fig. The structure shown in section 4 can be combined accordingly. The structure in the illustration of the Fig. Figure 5 shows a guide pin 39, which is rigidly connected to the base body 34. In the lower, closed position of the extraction piston 17 shown here, it engages in a guide bore 40 arranged in the extraction piston 17, thus ensuring that the extraction piston 17 is guided in a rotationally secure manner. This is particularly advantageous in the area of ​​the seals 18 and their contact surface 19, as these two elements adjust to each other over time, so that any inaccuracies and depressions in the surface are reflected in the seal 18, and vice versa. If this position of the parts relative to each other is then no longer changed, an improved seal is achieved.

[0032] As already mentioned, the diameter of the bypass bore 35, or of a throttle point 38 within it, should ideally be smaller or much smaller than the opening diameter of the pilot bore 23 to ensure optimal opening of the extraction valve 4. This allows the gas inside the pressure sleeve 9 to flow through the pilot bore, out through the discharge opening 8 in the extraction piston 17, and through the central extraction opening 20, for example, into the area of ​​an internal combustion engine or a fuel cell. If rapid outflow is possible with low back pressure in the extraction opening 20, gas from the annular space 10 flows slowly through the bypass bore 35, or its throttle point 38 if present. The pressure in the annular space 10 then moves the extraction piston 17 upwards, where it is held magnetically.Conversely, it would be desirable for the bypass bore 35 to have a larger diameter than the pilot bore 23, as only then can an exchange in the opposite direction be achieved—that is, a faster flow of gas into the interior of the pressure sleeve 9 than flows out through the pilot bore 23. This would facilitate the rapid and reliable closing of the extraction piston 17 when the electromagnetic field is switched off. To achieve precisely this configuration, as shown in the illustration of the... Fig. As can be seen in Figure 6, according to an advantageous embodiment of the inventive idea, a needle 41 is arranged in the base body 34, which interacts accordingly with the throttle bushing 37 or a throttle point 38 of the bypass bore 35. The throttle bushing 37 represents a favorable variant of the design; in principle, however, the design without the throttle bushing 37 would also be conceivable.

[0033] The needle 41 is firmly connected to the base body 34. In the Fig. In the lower position of the extraction piston 17 shown in Figure 6, i.e., when the extraction valve 4 is closed, a cylindrical section of the needle 41 lies at least partially inside the bushing 37. This ensures that only a small cross-sectional area is open for flow, which corresponds approximately to a bypass bore 35 with a very tight restrictor 38, for example, with a restriction to a few µm. Depending on the manufacturing precision, a metallic seal can also be achieved between the cylindrical part of the needle 41 and the corresponding part of the restrictor 38 in the restrictor bushing 37. The needle 41 tapers to a point at the front, which can be achieved, for example, by three surfaces attached to it in a relatively robust design. When the extraction piston 17 now moves to its upper open position, which is shown in Figure 6, the needle 41 is opened. Fig. As can be seen in Figure 7, the needle 41, which is firmly connected to the base body 34, and the throttle bushing 37 around the needle 41 lift away from each other to such an extent that a comparatively large flowable cross-section is opened. This relatively large flowable cross-section is ideally larger than the diameter of the pilot bore 23, for example, it is on the order of approximately 300–500 µm. With the extraction valve 4 open, this creates a situation that causes the extraction valve 4 to close very quickly when the coil 12 is switched off, because gas can flow into the interior of the pressure sleeve 9 through the bypass bore 35 faster than it flows out through the pilot bore 23. This generates an additional pressure force, which assists in moving the extraction piston 17 downwards and achieves the desired seal in the area of ​​the seals 18 and their mating surfaces 19.

[0034] In the presentation of the Fig. Figure 8 shows an alternative embodiment of the needle 41. The needle 41 is conical in its upper region and, in the embodiment shown here, interacts with a conically shaped throttle point 38 in the throttle bushing 37. The needle 41 itself is mounted in the base body 34 such that it is biased towards the extraction piston 17 by a spring element 42. At the same time, the material of the base body 34 and a widening 43 on the needle 41 form a stop, so that the travel of the needle 41 towards the extraction piston 17, as shown in the illustration, is limited. Fig. 8 is also limited upwards accordingly. In the embodiment shown here, with the extraction piston 17 in its closed position, the spring 42 is slightly compressed, ensuring a secure and reliable contact of the needle 41 in the area of ​​the throttle point 38. Ideally, the surfaces are adapted to each other, at least after some operating time, to such an extent that a reliable metallic seal is achieved. The flowable cross-section in this situation is therefore zero to a few µm and is thus much smaller than the flowable cross-section of the pilot bore 23. By using the spring 42 and the conically shaped needle 41 on the one hand, and the throttle bushing 37 on the other, a secure and reliable seal is achieved in this situation with comparatively low requirements for manufacturing tolerances.

[0035] When the extraction piston 17 moves upwards again to its open position, the needle 41 lifts off its mating surface in the throttle bushing 37. This is because the stop formed by the widening 43 and the material of the base body 34 limits the travel of the needle 41, and this travel is smaller than the possible travel of the extraction piston 17. This allows a gap to form between the needle 41 and its mating surface in the throttle bushing 37, which provides a larger flow cross-section than in the other position of the extraction piston 17, ideally a cross-section larger than the flow cross-section of the pilot bore 23. The design is different from that described in the Fig. 6 and Fig. The structure described in section 7 is comparable, but the use of the spring element 42 makes it somewhat cheaper to manufacture, as lower manufacturing tolerances must be observed.

[0036] Regarding further possible embodiments of the extraction valve 4, in particular with regard to the armature 10, the core 15, the rod 25 and the springs interacting with it, reference is made to the aforementioned earlier EP 1 682 801 B1. The embodiments described therein can be combined arbitrarily with the bypass bore 35 in the embodiments described here.

Claims

[1] Withdrawal valve (4) for a gas under overpressure from a pressure gas storage device (2), with 1.1 a pressure sleeve (9) closed on one side; 1.2 a movable removal piston (17) which, through its movement, opens or closes a removal cross-section and which projects at least partially into the pressure sleeve (9) on the open side thereof; 1.3 an electromagnetic coil (12) which at least partially surrounds the pressure sleeve (9); 1.4 an armature (16) made of magnetizable material, movable in the pressure sleeve (9); 1.5 a pilot bore (23) in the extraction piston (17) which connects the interior of the pressure sleeve (9) with an outflow opening (8) for the extracted gas; 1.6 a sealing element (24) which is pressed sealingly against the pilot bore (23) by a spring element (26); 1.7 an operative connection between the sealing element (24) and the armature (16) such that when the armature (16) moves, the sealing element releases the pilot bore; 1.8 the extraction piston (17) is formed on its side facing the armature (16) at least partially from magnetizable or permanently magnetic material (22); characterized by , that 1.9 the extraction piston (17) is sealed off from the pressure sleeve (9) by means of a seal (36); and that 1.10 a bypass bore (35) is arranged in the extraction piston (17), which extends between the side of the extraction piston (17) facing the area connected to the compressed gas reservoir (2) and the side of the extraction piston (17) facing the interior of the pressure sleeve (9); and wherein a throttle point (38) is arranged in the bypass bore (35); and a needle (41) projecting in the direction of the extraction piston (17) is arranged in a base body (34), which needle interacts with the throttle point (38) in such a way that, depending on the position of the extraction piston (17), a different diameter is released in the area of ​​the throttle point (38). [2] Extraction valve (4) according to claim 1, characterized by that the base body (34) which is firmly connected to the pressure sleeve (9) is arranged on the side of the removal piston (17) facing away from the interior of the pressure sleeve (9). [3] Removal valve (4) according to one of the preceding claims, characterized bythat the throttle point (38) has a smaller diameter than the pilot bore (23). [4] Removal valve (4) according to one of the preceding claims, characterized by that the throttle point (38) is arranged in a throttle bushing (37) which is introduced, in particular pressed, into the bypass bore (35). [5] Removal valve (4) according to one of the preceding claims, characterized by that the needle (41) in the end position of the extraction piston (17) facing away from the interior of the pressure sleeve (9) interacts with the throttle point (38) in such a way that no flow cross-section or a much smaller flow cross-section is released than in the other end position of the extraction piston (17). [6] Extraction valve (4) according to claim 5, characterized bythat the needle (41) in the end position of the extraction piston (17) facing away from the interior of the pressure sleeve (9) interacts with the throttle point (38) in such a way that a smaller or much smaller flow cross-section is released than in the other end position of the extraction piston (17). [7] Extraction valve (4) according to claim 6, characterized by that the smaller flow cross-section is smaller or much smaller than the pilot bore (23) and a larger flow cross-section released by the movement of the extraction piston is larger than the pilot bore (23). [8] Removal valve (4) according to one of the preceding claims characterized by that a sealing surface, in particular a metallic one, is formed between the needle (41) and the removal piston (17) when the removal piston (17) is in its end position facing away from the interior of the pressure sleeve (9). [9] Removal valve (4) according to one of the preceding claims, characterized bythat the tip of the needle (41) tapers through at least two attached surfaces. [10] Extraction valve (4) according to one of claims 2 to 9, characterized by that a guide pin (39) is arranged in the base body (34), which guide pin interacts with a guide bore (40) in the extraction piston (17) in such a way that the extraction piston (17) cannot rotate about its longitudinal axis. [11] Use of the extraction valve (4) according to one of the preceding claims for extracting gas as fuel for a vehicle (1) from a compressed gas storage device (2) in which the gas is stored at a nominal pressure of more than 250 bar, in particular more than 650 bar.

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