Check valve for high-pressure gas applications

Abstract

Check valve (9) for high-pressure gas applications, comprising a first and a second housing part (10.1, 10.2) which together form a valve housing (10), with a valve seat (16) in the valve housing (10) and a valve body (20) movable in the valve housing (10) against the force of a spring (23), wherein a metallic seal (28) is provided between the two housing parts (10.1, 10.2), characterized in that the metallic seal (28) consists of a circumferential conical groove (27) formed integrally with one of the housing parts (10.2) on the one hand and a spherically formed surface section (26) formed integrally with the other housing part (10.1) on the other hand.

Description

[0001] The invention relates to a check valve for high-pressure gas applications of the type defined in more detail in the preamble of claim 1. The invention also relates to the use of such a check valve.

[0002] Check valves are known from the general state of the art. They typically have a valve body which is pressed against a valve seat by the force of a spring element and which is lifted from the valve seat by the flow in one direction against the force of the spring, thereby opening a flow cross-section. Especially for high-pressure gas applications, such check valves must meet various requirements, which generally lead to very complex solutions and make the check valves correspondingly expensive, complicated, and heavy. Check valves are particularly complex and expensive for use with high-pressure hydrogen, i.e., hydrogen applications with a nominal pressure of more than 50 MPa, especially the currently common nominal pressure of 70 MPa.

[0003] For further examples of the state of the art, reference can be made to DE 10 2011 121 467 B4 for a different application. This check valve, also known as a pilot valve, serves, for example, as a withdrawal valve for high-pressure gases from a pressurized gas storage tank. It has a correspondingly complex design with several elastomeric seals. The resulting seal is generally insufficient, particularly for hydrogen applications.

[0004] Furthermore, reference can be made to JP 2009 - 145 120 A. This also features a comparable extraction valve, which includes a leakage bore that is particularly important for hydrogen applications. A suitable detector can be used in this bore to detect hydrogen leaks and / or collect escaping hydrogen. The valve described above also has similar bores.

[0005] Furthermore, a check valve with a correspondingly complex design is known from US 2011 / 0 266 472 A1. The design is specifically intended to ensure high functionality even with fluids containing contaminants and to minimize wear in the valve. For this reason, it uses a separate sealing ring made of a metallic material for connection to a flange.

[0006] From JP 2014 - 1 765 A, a check valve is known, comprising a body that includes a pipe connection part and a cylindrical space part, and a cap body that includes a pipe connection part and a valve seat sealing surface. These are threaded and connected to each other via a seal, and a poppet valve element is attached by means of a spring so that it rests with a flat section against the valve seat sealing surface.

[0007] US 2 653 792 A discloses a valve assembly comprising an elongated tubular metal body with complementary parts or sections that can be connected by threads to clamp a relatively soft metal seal between circular shoulders of the sections.

[0008] US 2,722,232 A discloses a valve comprising a nipple threaded to one end of a coupling. The nipple has an annular flange. A metal gasket is located between this flange and the adjacent end of the coupling to prevent leakage of high-pressure fluid from the connection between the nipple and the coupling.

[0009] The object of the present invention is to provide a check valve for high-pressure gas applications according to the preamble of claim 1, which can be constructed simply and efficiently, and which ensures a very good seal of the valve housing against the environment over a very large operating range - with regard to pressures and temperatures.

[0010] According to the invention, this problem is solved by a check valve having the features in the characterizing part of claim 1. Advantageous embodiments and further developments are described in the dependent claims. Claim 10 also specifies a particularly preferred use for the check valve.

[0011] The check valve according to the invention for high-pressure gas applications consists, similarly to comparable valves from the prior art, of two housing parts which together form the valve housing. Within this housing is a valve seat and a valve body movable within the valve housing against the force of a spring. The valve body is designed to interact with the valve seat in a sealing manner and can be lifted away from the valve seat against the force of the spring. According to the invention, a metallic seal is provided between the two housing parts. Such a metallic seal between the housing parts enables a very good and efficient seal with very few components and eliminates the risk of sealing elements being damaged by incorrect assembly, which is a considerable risk when using elastomeric sealing elements.Furthermore, a metallic seal can ensure a high level of tightness over very wide temperature ranges. Particularly in automotive applications of the check valve, temperature ranges between -50°C and +100°C must be covered. Typically used elastomeric seals, which, for example, exhibit a high level of tightness against hydrogen gas in high-pressure applications, typically have a relatively high glass transition temperature, meaning that such sealing elements become brittle and hard very quickly at low temperatures. They are then often no longer suitable for providing a sufficient seal. By using a metallic seal between the housing parts, these problems are avoided, and a design is provided that can be assembled with exceptional tightness even over a wide range of temperatures and pressures.

[0012] Furthermore, the metallic seal consists of a circumferential conical groove, formed integrally with the housing parts, and a spherical surface section. This one-piece integration of a groove into one housing part and a projecting, spherical section into the other allows for exceptionally simple assembly, as the necessary sealing elements are already integrated into the housing parts. The housing parts then only need to be joined together, typically by tightening them to the specified torque, usually by screws, to ensure a secure and reliable seal. No additional components, such as an inserted gasket, are required.

[0013] A particularly advantageous design involves forming the valve seat as a body pressed into one of the housing parts. Such a valve seat pressed into the valve housing enables a very good internal seal for the check valve, as the valve seat can be machined relatively easily and with comparatively high precision outside the housing part and then pressed into it. A seat machined as a single piece within the housing part would be significantly more complex to machine due to the limited space inside the housing part, especially if comparable machining quality is desired.

[0014] The pressed-in body with the valve seat can have a circumferential groove on the side of the body facing away from the flow direction. Such a circumferential groove enables pressure activation, resulting in an increased sealing effect of the valve body on the valve seat.

[0015] According to an advantageous embodiment, the valve body of the check valve according to the invention can be formed by a piston with a streamlined shape in the direction of the oncoming gas flow. Such a streamlined piston allows for low flow resistance through the check valve when it is opened and the high-pressure gas flows through it. Furthermore, the piston shape enables very good guidance within the check valve, effectively preventing tilting, while still achieving lower flow resistance than would be the case, for example, with a sphere. Ideally, the streamlined shape of the piston is designed in the form of a dolphin's nose, which represents a known streamlined cross-section exhibiting exceptionally favorable flow characteristics.

[0016] A further highly advantageous embodiment of the check valve according to the invention provides that the piston has flow-through openings between the streamlined section designed as the valve body and a section guiding the spring. The flow thus does not occur along the piston, but rather the piston has corresponding openings behind the valve body, so that the gas which has flowed around the streamlined section serving as the valve body flows into the interior of the piston and from there continues to flow. Conversely, according to a highly advantageous further development, this allows the piston to have a projection, e.g., on its end facing the streamlined section.The piston has a contact surface or edge that acts as a stop or end stop for the spring on the one hand and as a primary guide against the valve housing on the other, and that the piston is guided at its other end in the valve housing in the manner of a sliding seal. Particularly in combination with the flow through the piston's interior, this creates a structure that guides a spring, for example a coil spring, very effectively between the valve housing and the outside of the piston, thus ensuring good functionality without the risk of tilting.

[0017] A highly advantageous further development of the check valve according to the invention provides that the valve body has an external thread on its first side (in the flow direction) and an internal thread on its second side as a connection. This design with an internal thread on one side and an external thread on the other ensures that the check valve is always installed correctly, since incorrect installation due to the non-interacting threads to its connection is prevented. This design is also known as a "poka-yoke design".

[0018] A further exceptionally advantageous embodiment of the check valve according to the invention provides that a connecting bore to the environment is formed in one of the housing parts on the side of the metallic seal facing away from the gas. Such a leakage bore is particularly advantageous in hydrogen applications. Any gas leaks that may penetrate the metallic seal can be discharged to the outside via this bore. The targeted discharge into a specific area on the outside of the valve housing represents a safety advantage. Furthermore, the targeted discharge into a corresponding area also allows leaks in the area of ​​the metallic seal between the housing parts of the check valve to be located quickly and easily, for example, by means of a manually guided leakage probe.

[0019] According to a further development of this idea, the connecting bore is also designed to terminate in a groove circumferentially around the valve housing, in which a pre-tensioned sealing ring is inserted. Such a groove with a pre-tensioned sealing ring allows for a very simple and efficient seal of the connecting bore terminating in the groove against, for example, moisture, contamination, or the like, since the externally inserted sealing ring, which does not have to meet any sealing requirements against the gas, especially hydrogen, can provide a very simple and efficient seal. In particular, a sealing ring made of silicone rubber can be used here, which exhibits high elasticity even at very low temperatures and offers a good seal against moisture, splashing water, dirt, and the like across all temperatures.

[0020] As already mentioned, the check valve according to the invention can be used, in particular, in a high-pressure hydrogen system. According to an advantageous application of the check valve according to the invention, it is therefore intended that it be used in a high-pressure hydrogen system. This high-pressure hydrogen system can, in particular, be located in a vehicle where especially high demands are placed on leak tightness over a wide temperature range. The simple, lightweight, and therefore cost-effective check valve, which is easy to manufacture and install, is ideally suited for such applications.

[0021] Further advantageous embodiments of the check valve according to the invention and its use will become apparent from the exemplary embodiment, which is described in more detail below with reference to the figures.

[0022] This shows: Fig. 1. A vehicle, indicated in principle, with a fuel cell system which is supplied with fuel by a high-pressure hydrogen system; and Fig. 2 a representation of a possible embodiment of a check valve according to the invention in an open position above the center line and a closed position below the center line.

[0023] In the presentation of the Fig. Figure 1 is a highly schematic representation of a vehicle 1, which is to be driven by an electric drive motor 2. The power for the electric drive motor 2 is processed by power electronics 3 and supplied by a fuel cell 4. The fuel cell 4 is supplied with air as an oxygen source on its cathode side via an air supply system 5 in a manner known per se. Hydrogen from a pressurized gas storage tank 6 is supplied to the fuel cell 4 on the anode side. The hydrogen enters the fuel cell 4 via a tank valve 7 on the pressurized gas storage tank 6 and via a pressure control and metering unit 8 (indicated). In the embodiment shown here, exhaust gases from the fuel cell 4 are discharged directly into the environment. This setup is shown in an extremely simplified form.Fuel cell systems for vehicles 1 are familiar to those skilled in the art, and they are already acquainted with variants and alternatives, for example regarding gas flow, the use of fuel cell exhaust gases, and the like. Since this is of minor importance for the present invention, it need not be discussed further.

[0024] The hydrogen system in vehicle 1 is designed as a high-pressure system. The hydrogen in the pressurized gas storage tank 6 is stored at a nominal pressure of 70 MPa. This high-pressure hydrogen system typically contains several metering and control valves. Furthermore, it is characteristic of such high-pressure hydrogen systems that they have at least one check valve 9, even if this is not shown in the illustration. Fig. 1 is not explicitly shown and cannot be identified. High demands are now placed on such check valves 9 with regard to the pressure loss they generate on the one hand, and tightness and reliable functionality on the other. Typically, this is only achieved by one or more elaborate valve components, which are accordingly expensive, heavy, and complex. Their complexity also makes them very prone to failure.

[0025] In the presentation of the Fig. Figure 2 shows an improved check valve 9, which is exceptionally simple, safe, and reliable. Above the symmetry or center line of the check valve 9, which is shown in the illustration of the Fig. Figure 2, labeled A, shows the check valve 9 in an open position, in which the hydrogen H2 flows through the check valve 9 according to the flow direction shown. The flow path is represented by a dotted line inside the check valve 9. The area below the center line A of the check valve 9, on the other hand, shows the check valve 9 in a closed position, i.e., when the pressure exerted by the hydrogen is insufficient to open the check valve 9.

[0026] With reference to the illustration with these two operating states, the check valve 9 is described in more detail below.

[0027] The check valve 9 essentially consists of a valve housing 10, which here is formed from two housing parts 10.1 and 10.2. The incoming hydrogen enters, as can be seen from the illustration of the Fig. As can be seen in Figure 2, the hydrogen flows in from the left side. A corresponding line is connected to the valve housing 10 via an external thread 11. The outflowing hydrogen leaves the check valve 9 or its valve housing 10 in the illustration of the Fig. 2 on the right side. A connection with an internal thread 12 is provided for connecting a suitable pipe element or the like. This design with an internal thread 12 on one side and an external thread 11 on the other, whereby the sides could just as well be reversed, is particularly advantageous because it prevents the check valve 9 from being installed backwards, which would be highly detrimental to its function.

[0028] In the direction of hydrogen flow, the hydrogen first encounters a filter 13 within the valve housing 10, specifically within housing part 10.1 of the valve housing 10. This filter 13 consists of a support body 14 and a filter mat 15, which is arranged around the support body 14. The hydrogen flows through the filter mat 15 and enters the interior of the support body 14 via openings in the support body 14. The filter 13 can, for example, be pressed into housing part 10.1 of the valve housing 10. Following the filter 13, the hydrogen flows through a valve seat 16, which is formed in a body 17 containing the valve seat 16. This body 17 containing the valve seat 16 is ideally pressed into housing part 10.1 of the valve housing 10 and thus connected to it.On the rear side of the body 17 with the valve seat 16 (in the direction of hydrogen flow), a circumferential groove 18 is provided, which serves as a pressure activation mechanism. This increases the sealing effect between the valve seat 16 and a piston 19 pressed against the valve seat 16. The piston 19 has a streamlined body 20 on its front side (in the direction of flow), which forms the valve body 20 of the check valve 9. The valve body 20 is streamlined, specifically in the shape of a "dolphin nose," to minimize the pressure loss to the oncoming hydrogen when open. Following the valve body 20 in the direction of hydrogen flow, there is a section with flow-through openings 21, allowing the hydrogen, after flowing between the valve seat 16 and the valve body 20, to enter the interior of the piston 19 and from there flow out of the check valve 9.The piston 19 has a projection 22 on its outer surface in the section following the flow openings 21. This projection serves both as a stop for a spring 23 and as a guide for the piston 19 on a guide sleeve 24. At its other end, the end of the piston 19 is designed to form a sliding seal with the housing part 10.2 of the valve housing 10. This seal contributes to the precise guidance of the piston 19 and thus prevents it from tilting. The guide sleeve 24 has a circumferential groove on its outer surface, which surrounds the guide sleeve 24 in the form of a helix or thread, allowing any gas that may accumulate between the guide sleeve 24 and the housing part 10.1 of the valve housing 10 to escape. Furthermore, a stop 25 is formed in the area of ​​the guide sleeve 24. This stop may, for example, be a snap ring inserted into a groove in the guide sleeve 24.This stop 25 limits the force with which the spring 23 presses the valve body 20 against the valve seat 16.

[0029] In this assembly, it is crucial that the two screwed-together housing parts 10.1 and 10.2 of the valve housing 10 are securely and reliably sealed against each other, ensuring a high degree of tightness regardless of the temperatures to which the check valve 9 is exposed. At least within the typical temperature range for vehicles, from approximately -50°C to +100°C, tightness must be guaranteed under all circumstances. To achieve this, a metallic seal 28 is implemented between the housing parts 10.1 and 10.2 of the valve housing 10. For this purpose, the housing part 10.1 of the valve housing has a spherical or semicircular projection 26 on its end face facing away from the external thread 11. This projection interacts with a conical or trapezoidal groove 27 on the second housing part 10.2.These two parts together form the integrated metallic seal 28, which ensures a secure and reliable seal in all cases. The direct integration of the components required for the metallic seal 28 into the respective housing parts 10.1 and 10.2 of the valve housing 10 also guarantees simple and reliable assembly, as the two housing parts 10.1 and 10.2 of the valve housing 10 only need to be screwed together. For this purpose, wrench flats are indicated on the outer surface 6 and marked with the reference numeral 29. Typically, the tightening is carried out with a specified torque, ensuring a secure and reliable seal in all cases.

[0030] Especially in hydrogen or high-pressure hydrogen systems, leak tightness is of paramount importance. To facilitate easy verification of a reliable seal, the check valve 9 is designed with a connecting bore 32, which could also be referred to as a leak detection bore, located between the threaded connections 30 and 31 of the housing parts 10.1 and 10.2 (typically secured with thread-locking compound) and the metallic seal 28 of the housing parts 10.1 and 10.2. This connecting bore 32 connects the area between the threads 30 and 31 and the metallic seal 28 to the surrounding environment. A hydrogen leak could be easily detected in this connecting bore 32 using, for example, a manually operated leak detector with a hydrogen probe.To reliably prevent the ingress of dirt and moisture into the area of ​​the connecting bore 32, a groove 33 is provided in the second housing part 10.2 of the valve housing 10. A sealing ring 34 is placed in this groove under preload. The sealing ring 34 is thus inserted into the groove under preload and seals the connecting bore 32, which opens into the groove. In the event of a hydrogen leak, the hydrogen can escape due to a certain overpressure inside the area between the seal 28 and the threads 30, 31, slightly lifting the sealing ring 34 in the process. Furthermore, a suitable material, such as silicone rubber, can be used for the sealing ring 34. Such a material is highly elastic, even at very low ambient temperatures. It thus ensures a good seal of the connecting bore 32 against water and dirt.On the other hand, it is very permeable to hydrogen, at least at higher temperatures, so that any hydrogen leaks will in any case pass through the sealing ring 34 and thus become detectable in the area of ​​the connection opening 32. This further increases the safety of the check valve 9.

[0031] The design of the exemplary check valve 9 can, as already mentioned, be used at one or more points in the hydrogen system within the vehicle 1 and would replace a conventional or, according to the state of the art, much more complex and expensive check valve at this point.

Claims

[1] Check valve (9) for high-pressure gas applications, comprising a first and a second housing part (10.1, 10.2) which together form a valve housing (10), with a valve seat (16) in the valve housing (10) and a valve body (20) movable in the valve housing (10) against the force of a spring (23), wherein a metallic seal (28) is provided between the two housing parts (10.1, 10.2), characterized by , that the metallic seal (28) consists of a circumferential conical groove (27) formed in one part with one of the housing parts (10.2) on the one hand and a spherically formed surface section (26) formed in one part with the other housing part (10.1) on the other hand. [2] Check valve (9) according to claim 1, characterized by , that the valve seat (16) is formed on a body (17) pressed into one of the housing parts (10.1). [3] Check valve (9) according to claim 2, characterized by, that a circumferential groove (18) is provided on the side of the body (17) having the valve seat (16) that is facing away from the direction of gas flow. [4] Check valve (9) according to one of claims 1 to 3, characterized by , that the valve body (20) is designed as part of a piston (19), wherein the valve body (20) is streamlined in the direction of the oncoming gas. [5] Check valve (9) according to claim 4, characterized by , that the piston (19) has flow openings (21) between the valve body (20) and a section guiding the spring (23). [6] Check valve (9) according to claim 4 or 5, characterized by, that the piston (19) has a projection (22) in the direction of flow of the incoming gas after the valve body (20) and, if applicable, the flow openings (21) as a stop for the spring (23) and as a first guide for the piston (19), and that the piston (19) is guided at its other end in the valve housing (10) in the manner of a sliding seal. [7] Check valve (9) according to any one of claims 1 to 6, characterized by , that the valve body (10) has an external thread (11) on its first side and an internal thread (12) on its other side as a connection. [8] Check valve (9) according to any one of claims 1 to 7, characterized by , that in one of the housing parts (10.1, 10.2) on the side of the metallic seal (28) facing away from the gas a connecting bore (32) to the environment is formed. [9] Check valve (9) according to claim 8, characterized by, that the connecting bore (32) ends in a groove (33) circumferential around the valve housing (10), in which a sealing ring (34) is inserted under preload. [10] Use of the check valve (9) according to any one of claims 1 to 9, in a high-pressure hydrogen system in which the hydrogen is stored at a nominal pressure of more than 50 MPa. [11] Use of the check valve (9) according to claim 10 in a vehicle (1).

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