Device for venting gas from pressurized gas containers

Abstract

Device for venting gas stored under high pressure in a pressurized gas container (6), which flows out of the container via a safety valve (11) or a discharge valve through a discharge opening, comprising a vent line (12) connecting the discharge opening to an area in the vicinity of the pressurized gas container (6), wherein the vent line (12) has an opening (16) on its side facing away from the discharge opening that can be closed with a check valve (15), wherein the check valve (15) has a valve body (17) pressed against a valve seat (18) by a spring (20), which is lifted from the valve seat (18) by the gas pressure against the force of the spring when gas is vented, and wherein the valve body (17) is guided in the vent line (12) by longitudinal ribs (25) arranged on its inner wall.

Description

[0001] The invention relates to a device for venting gas of the type defined in more detail in the preamble of claim 1. The invention also relates to the use of such a device.

[0002] Devices for venting gas from pressurized gas containers are known from the general state of the art. Typically, pressurized gas containers, for example, those for storing hydrogen at a nominal pressure of 700 bar, particularly in a fuel cell vehicle, have safety devices to vent the pressurized gas in the event of overpressure. These safety devices can be, for example, fusible links or safety devices that open upon an increase in temperature, such as bursting glass ampoules. A manual vent valve may also be present. Typically, all these methods for venting gas from the pressurized gas container terminate in the area of ​​a discharge opening, for example, in a valve housing.From the vent opening, a vent line, also frequently referred to as a venting tube, typically leads to an area where the gas can be safely released. In the example above, where gas is released from a pressurized hydrogen storage tank in a fuel cell vehicle, the vent line might lead to the underbody of the vehicle. The gas, in this case hydrogen, can then be released into this area with relatively little risk.

[0003] The problem arises, particularly when used in vehicles, if splash water or especially water that enters the blow-off line during vehicle cleaning in a car wash with high-pressure underbody cleaning or manually with a pressure washer. This can lead to corrosion and potentially impair the safety devices in the area of ​​the pressurized gas cylinder or its valve.

[0004] Solutions are known from the prior art, particularly for upward-facing exhaust ducts. Such solutions are described, for example, in US 5,267,894 A and similarly in DE 102 00 281 A1. As mentioned in the German patent application, the closures serve primarily to prevent the ingress of rain. The US patent describes a highly complex design for this purpose, which uses counterweights to ensure that a flap is normally closed by gravity, only being forced open by the outflowing gas. This design is exceptionally complex, elaborate, and expensive, and can only be used in the described manner with an upward-facing exhaust duct.However, blow-off lines, especially when used in vehicles, often lead underneath the vehicle, so their use here is not an option.

[0005] Furthermore, the prior art for liquids includes a check valve as described in DE 29 41 244 A1. The check valve for liquids described therein consists of a ball as the valve body, which is pressed against a valve seat by a coil spring. The ball is guided by longitudinal ribs arranged on the inner wall of the housing.

[0006] Furthermore, DE 10 2013 226 913 A1 describes a device for draining at least one flammable fluid from a container. Fluid outlet openings are provided along fluid paths, which are preferably spaced apart from each other and point in different directions.

[0007] The object of the present invention is to provide a device for venting gas according to the preamble of claim 1, which is improved compared to the prior art and which in particular avoids the aforementioned disadvantages.

[0008] According to the invention, this problem is solved by a device having the features in the characterizing part of claim 1. Advantageous embodiments and further developments of the idea are described in the dependent claims. Claim 10 also specifies a preferred use of the device according to the invention.

[0009] In the device according to the invention, the side of the blow-off line facing away from the discharge opening has a check valve that opens when gas flows. In the check valve, a valve body is pressed against a valve seat by a spring, and when gas is discharged, the gas pressure lifts the valve body from the valve seat against the force of the spring, thus releasing the opening. The valve body is guided in the blow-off line by longitudinal ribs arranged on its inner wall. Such guidance by longitudinal ribs ideally stabilizes the valve body in its movement, preventing it from tilting. At the same time, the contact area is very small, particularly if, according to an advantageous embodiment, the longitudinal ribs are tapered towards the valve body.This significantly reduces the risk of the valve body freezing to the blow-off line, thus ensuring safe and reliable functionality in all operating situations.

[0010] In the device according to the invention, the check valve with its valve body securely and reliably seals the vent line against the ingress of moisture and dirt. When preferably used with a pressurized gas container in which hydrogen is stored at a nominal pressure of 700 bar, an overpressure of approximately 15 bar is present in any case, even when the container is empty, as the gas flows out through the vent line. The spring that presses the valve body against the valve seat can therefore be made comparatively strong. If the check valve is then exposed to moisture from the outside, for example, it is securely closed, so that no moisture can enter the system.Even the use of a high-pressure cleaner or high-pressure underbody cleaning on a vehicle is insufficient to open the check valve, thus ensuring the vent line remains reliably free of dirt and water. Water and dirt can only penetrate the area between the actual opening and the check valve. However, this is a relatively short distance, and with the preferred design where the opening is positioned downwards due to gravity, the water can easily drain away. Any dirt is reliably expelled by the gas pressure when the gas is vented through the vent line.

[0011] As already mentioned, the device according to the invention can be used particularly in the area of ​​pressurized gas containers, which are used in vehicles for storing hydrogen or compressed natural gas. The corresponding advantages can be achieved specifically for this application, as large production volumes are expected. The very simple and cost-effective design, as well as the correspondingly simple assembly, are therefore a decisive advantage. Furthermore, such an application places special demands on safety, which can be easily met by the device according to the invention. Here, too, it has decisive advantages over designs according to the prior art, especially since it is particularly resistant, for example, to water ingress from car washes and high-pressure cleaners, which are very frequently used as cleaning equipment in the vehicle sector.

[0012] Further advantageous embodiments of the device according to the invention also result from the further dependent subclaims and become clear with reference to the exemplary embodiment, which is described in more detail below with reference to the figures.

[0013] This shows: Fig. 1 an exemplary fuel cell vehicle with a pressurized gas container for hydrogen; Fig. 2 a cross-sectional view through one end of the blow-off pipe in the vehicle; Fig. 3 the end of the blow-off line with the valve body in longitudinal section according to line III - III in Fig. 5; Fig. 4 a top view of the end of the blow-off pipe according to IV in Fig. 3; and Fig. 5 the end of the blow-off line with the valve body in cross-section according to the line V - V in Fig. 3.

[0014] The device according to the invention is explained and described in more detail below using an embodiment and application example in a fuel cell vehicle with a hydrogen tank equipped with the device according to the invention. The device according to the invention can also be used for vehicles powered, for example, by hydrogen or compressed natural gas via an internal combustion engine. The device according to the invention can also be used outside of a vehicle, but due to its compact design, simple assembly, and very safe embodiment, it is preferably used in vehicles.

[0015] In the presentation of the Fig. Figure 1 is a highly schematic representation of a vehicle 1, which is powered by an electric drive system via a fuel cell 2. The fuel cell 2 comprises a cathode section 3, to which air is supplied as an oxygen source, and an anode section 4, to which hydrogen is supplied from a storage device 5 for storing hydrogen under high pressure. The entire storage device 5, which typically consists of various pipes, valve assemblies, a tank connection, and one or more pressure gas containers 6, is shown in the illustration as an example. Fig. Figure 1 only indicates one of the pressurized gas containers 6. This is connected via a hydrogen line 7 to the anode area 4 of the fuel cell 2, which typically contains pressure regulating and metering units and the like. The fuel cell 2 supplies electrical power, which is processed accordingly by power electronics 8 and passed on to a drive motor 9 (shown in principle), which then serves to propel the vehicle 1.

[0016] It is now the case that, particularly when storing hydrogen in the storage device 5 or its at least one pressure vessel 6, nominal pressures on the order of 700 bar are generally known and common, and even higher pressure levels are already being considered. In the event of an accident involving vehicle 1, such a storage device 5 or its pressure vessels 6 poses a considerable hazard, for example, if the storage device 5 is heated to a very high temperature by a fire. In the worst case, an explosion could occur.

[0017] To counteract this inherent danger, it is generally known and customary to install safety valves in the storage device 5 or in the area of ​​the pressurized gas containers 6. Generally, each pressurized gas container 6 has a connection fitting at one end with a valve assembly, for example, a so-called on-tank valve (OTV), which is connected to the hydrogen line 7. The aforementioned safety valve is arranged in the area of ​​this valve assembly in a manner known per se. This safety valve is connected via a discharge port to a vent line 12, which ensures that, in the event of the safety valve being activated, the hydrogen is vented in a controlled manner to escape as quickly as possible from the area where the passengers are located, thereby reducing the risk of fire or explosion should flammable mixtures form.The blow-off line 12 can be connected to one or, if present, to several pressurized gas containers 6 of the storage device 5.

[0018] In the presentation of the Fig. Figure 2 shows the end of the blow-off line 12 facing away from the discharge opening and the pressure gas container 6. In the illustration, this end of the blow-off line 12 is bent backwards in the direction of travel (F) and terminates above an opening 13 in an underbody panel 14 of the vehicle 1. The axis of the blow-off line 12, labeled A, therefore runs at an angle of 45° to gravity in its end region in the embodiment shown here, during normal operation. The end of the blow-off line 12 is cut off at another angle of 45° to this axis A and is fitted with a check valve 15, indicated in the figure, which will be discussed in more detail later. The blow-off line 12 may also be provided with thermal insulation, which is not shown here.

[0019] In the presentation of the Fig. Figure 3 shows the aforementioned check valve 15. Unlike in the illustration of the Fig. In this case, the open end of the blow-off line 12 is cut off perpendicular to the axis A of the blow-off line 12. This configuration is also conceivable in principle, as long as any water that may have entered can drain away again through a lower opening 16 due to its orientation downwards in the direction of gravity g during intended use. The check valve 15 has a ball as its valve body 17, which rests on a corresponding valve seat 18, i.e., an annular edge or spherical cap. In the area of ​​this valve seat 18, a sealing element 19, particularly in an O-ring configuration, as shown in the illustration of the Fig. 3 indicated, arranged. This further improves the seal between the valve seat 18 and the ball as valve body 17.

[0020] The ball, as valve body 17, is, as already shown in the illustration of the Fig. 2 indicated, is pressed against the valve seat 18 and / or the sealing element 19 by a spring 20. The spring 20 is supported by an end cap 21 which closes the open end of the blow-off line 12. The end cap 21, which is shown in the illustrations of the Fig. 3 on average and in the representation of the Fig. As can be seen in a top view (Figure 4), the end cap 21 includes a central spring pin 22 for guiding the spring 20, preventing the spring 20 from shifting uncontrollably. Another crucial component of the end cap 21 is the numerous openings 23, only some of which are marked with a reference symbol. These openings 23 allow gas to escape when the valve body 17 is lifted from the valve seat 18. At the same time, the openings 23 are designed so that, particularly when exposed to a high-pressure jet, water cannot penetrate completely unhindered. Otherwise, it could twist or cause the ball used as the valve body 17 to rotate, allowing moisture to enter the interior of the blow-off line 12 between the valve body 17 and the valve seat 18 or the sealing element 19.To counteract the rotation of the valve body 17 even more effectively when exposed to the jet of a high-pressure cleaner, an additional insert 24 is provided between the end cap 21 and the valve body 17. This insert reduces the inner diameter of the blow-off line 12, thereby preventing the valve body 17 from being blasted in its edge region by the jet of a high-pressure cleaner. Preferably, the insert 24 is designed transversely or perpendicular to the axis A of the blow-off line 12 on its side facing the end of the blow-off line 12 in this region, while the opposite side is inclined to offer the least possible resistance to the escaping gas, unlike the jet of a high-pressure cleaner.

[0021] To ensure the secure guidance of the spherical valve body 17 on the one hand, and to prevent freezing as much as possible on the other, longitudinal ribs 25 are provided inside the blow-off line 12 between the valve seat 18 and the end of the blow-off line 12, which guide the valve body 17 accordingly. To minimize the contact area, which offers corresponding advantages with regard to the risk of freezing, as can be seen in the sectional view of the Fig. As can be seen in Figure 5, at least three – preferably six – such longitudinal ribs 25 are provided, evenly distributed around the circumference. This ensures secure and reliable guidance, preventing the valve body 17 from tilting. Simultaneously, the minimized contact area reduces the risk of freezing to an absolute minimum. This design results in a very safe and reliable construction, which, even under adverse conditions and moisture in the area of ​​the end of the vent line 12, ensures that gas can be safely and reliably vented when required. As shown in the illustration of the Fig. As can be seen in Figure 5, the longitudinal ribs 25 are tapered to a point in order to further minimize the contact area with the valve body 17.

[0022] The non-return valve 15 according to the invention can be designed and mounted particularly simply and efficiently by constructing an end section 26 with the components necessary for the non-return valve 15. This end section 26 can then simply be slid over the end of the blow-off line 12 and mounted accordingly, as shown in the illustration. Fig. 3 can be seen in principle. This end section 26 includes both the spring 20 and the mounting part 24. Furthermore, the inwardly tapered longitudinal ribs 25 are integrated into this end section. The inner edge of the original end of the blow-off pipe 12 then serves as the valve seat 18. The assembly, together with the end cap 21, can then be easily slid over the existing pipe end and secured accordingly, for example by crimping, gluing, soldering, or the like.

[0023] At the nominal pressure of 700 bar in the pressure gas containers 6 of the storage device 5, minimum pressures on the order of 15 bar occur even in the case of an "empty" storage device 5. If a safety-relevant release of gas occurs via the vent line 12, then a pressure of at least 5 bar or more prevails inside it, which is easily sufficient to open the valve body 17, even if it is pressed relatively firmly against the valve seat 18 by the spring 20 in order to reliably and securely seal the vent line 12 against high-pressure cleaners and other external influences on the check valve 15.

Claims

[1] Device for venting gas stored under high pressure in a pressurized gas container (6), which flows out of the container via a safety valve (11) or a discharge valve through a discharge opening, comprising a vent line (12) connecting the discharge opening to an area in the vicinity of the pressurized gas container (6), wherein the vent line (12) has an opening (16) on its side facing away from the discharge opening that can be closed with a check valve (15), wherein the check valve (15) has a valve body (17) pressed against a valve seat (18) by a spring (20), which is lifted from the valve seat (18) by the gas pressure against the force of the spring when gas is vented, and wherein the valve body (17) is guided in the vent line (12) by longitudinal ribs (25) arranged on its inner wall [2] Device according to claim 1, characterized by, that each of the longitudinal ribs (25) ends in a pointed shape towards the center of the blow-off pipe (12). [3] Device according to claim 1 or 2, characterized by , that the valve body (17) is designed as a sphere. [4] Device according to any one of claims 1 to 3, characterized by , that the spring (20) and the valve body (17) are arranged between the valve seat (18) and the end of the blow-off line (12) and are supported in particular on an end cap (21) provided with openings (23). [5] Device according to any one of claims 1 to 4, characterized by , that an end section (26) with the longitudinal ribs (25) of the spring (20) and the valve body (17) is mounted on the end of the blow-off line (12), the edge of the end of the original blow-off line (12) serving as the valve seat (18). [6] Device according to any one of claims 1 to 5, characterized by that the valve seat (18) has a sealing element (19), in particular an O-ring. [7] Device according to any one of claims 1 to 6, characterized by , that the opening (16) points downwards in the direction of gravity (g) when used as intended, wherein in particular the end of the blow-off line (12) provided with the opening (16) runs at an angle oblique to gravity (g) when used as intended. [8] Device according to any one of claims 1 to 7, characterized by , that an installation part (24) reducing the cross-section of the blow-off line (12) is arranged between the valve body (17) and the end of the blow-off line (12). [9] Device according to claim 8, characterized by , that the installation part (24) runs transversely to the longitudinal axis (A) of the blow-off line (12) on its side facing the end of the blow-off line (12) and obliquely to the longitudinal axis (A) of the blow-off line (12) on its side facing the valve body (17). [10] Use of the device according to any one of claims 1 to 9, for venting hydrogen or compressed natural gas into a storage device (5) in a vehicle (1).

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