Abstract:
A shut-off valve to fill a tank with a gaseous medium. The shut-off valve includes a valve housing, a piston arranged in the valve housing for displacement in an axial direction and having an axially continuous bore, a first end piece having an outlet opening which is fluidically-connected to the axially continuous bore of the piston; and a second end piece having an inlet opening which is fluidically-connected to the axially continuous bore of the piston. A first end side of the piston and a first end side of the second end piece of the valve housing form a sealing seat upon contact therebetween.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority 35 U.S.C. §119 to European Patent Publication No. EP 14160244.1 (filed on Mar. 17, 2014), which may be hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    Embodiments relate to a shut-off valve to fill a tank with a gaseous medium. The shut-off valve includes a valve housing, a piston arranged in the valve housing for displacement in an axial direction and having an axially continuous bore, a first end piece having an outlet opening which is fluidically-connected to the axially continuous bore of the piston; and a second end piece having an inlet opening which is fluidically-connected to the axially continuous bore of the piston. A first end side of the piston and a first end side of the second end piece of the valve housing form a sealing seat upon contact therebetween. 
       BACKGROUND 
       [0003]    During filling of tanks with gaseous media, the filling is to be ended after a defined filling degree has been reached. In filling systems which communicate via infrared interfaces, for example, with a motor vehicle, there is the problem that filling is not possible in the case of fouling, damage or an unsuitable spacing of the infrared interfaces. 
         [0004]    A solution is therefore sought which automatically ends a filling operation when the tank is full. One possibility is electromagnetically actuated valves which open and close on the basis of signals. There is the risk here, however, that the explosive gaseous medium may ignite as a result of spark formation. A solution is therefore sought, in which a valve is used which is of purely mechanical configuration and ends the filling operation when the defined filling degree has been reached. 
         [0005]    Mechanically actuated valves are configured in such a way that, after a defined pressure has been reached, the valve closes automatically and further filling is thus prevented. 
         [0006]    European Patent Publication No. EP 0837280B1 discloses a one-way valve, comprising the valve cone, the valve cone guide, the valve seat and the spring, which is designed to permit the fluid flow in the downstream direction from the inlet opening to the outlet opening and to restrict the fluid flow in the upstream direction from the outlet opening to the inlet opening. 
       SUMMARY 
       [0007]    Embodiments relate to an enhanced shut-off valve which permits filling of a tank, the shut-off valve, actuated purely mechanically, to prevent further feeding of a gaseous medium after a defined pressure has been reached, independently of whether pressure increases, pressure decreases or pressure fluctuations occur on the feed side. 
         [0008]    Embodiments relate to an enhanced flow behaviour of a gaseous medium from an inlet opening in the direction of an outlet opening of the shut-off valve in accordance with embodiments, in order to achieve more rapid filling and an optimum filling degree of the tank. 
         [0009]    In accordance with embodiments, a shut-off valve for filling a tank with a gaseous medium, the shut-off valve including at least one of: a valve housing having a first end piece with an outlet opening, and a second end piece having an inlet opening; a piston which is axially displaceable in the valve housing, and which has an axially continuous piston bore which is fluidically-connected to the outlet opening and the inlet opening, and a first end side to form, upon contact with the second end piece, a sealing seat; a flow guiding device downstream of the inlet opening and which has at least one bore of the second end piece and a chamber, which bore leads radially to the outside and is fluidically-connected to the inlet opening of the second end piece, the chamber being configured between the piston and the second end piece, with the result that the gaseous medium is to flow from the inlet opening via the at least one radially outwardly arranged bore of the second end piece into the chamber and the gaseous medium in the chamber is directed from the outside to the inside in the direction of the first end side of the second end piece and a deflection of the gaseous medium is brought about in the direction of the axially continuous bore of the piston. 
         [0010]    In accordance with embodiments, a shut-off valve may include at least one of: a valve housing having a first end piece with an outlet opening, and a second end piece having an inlet opening and a first end side; a piston axially diaplceable in the valve housing and having an axially continuous piston bore which is fluidically-connected to the outlet opening and the inlet opening, and a first end side which, upon contact, forms a seal with the first end side; a flow guiding device downstream of the inlet opening and defining with the second end piece at least one radially-outwardly bore which is fluidically-connected to the inlet opening; and a chamber between the piston and the second end piece, wherein the gaseous medium is to flow from the inlet opening via the at least one bore into the chamber, where it is then directed towards the first end side of the second end piece where the gaseous medium deflected towards piston bore. 
         [0011]    In accordance with embodiments, a shut-off valve may include at least one of: a valve housing; a first end piece connected at one end of the valve housing, and having an outlet opening axially extending therethrough; a second end piece connected at another end of the valve housing, and having an inlet opening axially extending therethrough; a piston axially displaceable in the valve housing between the first and second end pieces, and which upon contact, forms a seal with the first end piece, and further which has a piston bore axially extending therethrough which is fluidically-connected to the outlet opening and the inlet opening; a flow guiding device downstream of the inlet opening and defining with the second end piece at least one radially-outwardly bore which is fluidically-connected to the inlet opening; and a chamber between the piston and the second end piece, wherein the gaseous medium is to flow from the inlet opening via the at least one bore into the chamber, and then directed towards the second end piece where the gaseous medium is deflected towards the piston bore. 
         [0012]    In accordance with embodiments, the valve housing may comprise a substantially hollow cylinder, in each case one internal thread is attached at both ends in the valve housing. A piston is arranged for axial displacement in the valve housing. The piston has an axially continuous bore which is fluidically-connected on one side to an inlet opening of the second end piece and on the other side to the outlet opening of the first end piece. Upon contact with a first end side of the second end piece, a first end side of the piston forms a sealing seat which seals in accordance with a set or predetermined shut-off pressure, and ignores (and remains closed) a further pressure increase, pressure decrease or any pressure fluctuations on the inlet side of the second end piece, for example, pressure fluctuations caused by the filling system. 
         [0013]    Opening of the shut-off valve is not possible without a pressure decrease on the outlet side of the first end piece or upon removal of medium from the tank or the tank system, which removal is caused by usual operation. The end side of the piston and end side of the second end piece are also understood to mean any end-side structural formation which is provided for configuring the sealing seat. For example, as will be described in greater detail later, the first end side of the second end piece may have a contour, in particular a concave contour. The piston is spaced apart from the first end side of the second end piece in the pressureless state. 
         [0014]    In accordance with embodiments, a flow guiding device is arranged downstream of the inlet opening. The flow guiding device serves to enhance flow of the gaseous medium from the inlet opening in the direction of the outlet opening by way of targeted deflection of the flow of the gaseous medium. The flow guiding device comprises substantially bores of the second end piece, and a chamber, which bores lead radially to the outside and are fluidically-connected to the inlet opening of the second end piece, and by way of which chamber the gaseous medium is directed from the outside to the inside in the direction of the first end side of the second end piece and a deflection of the gaseous medium is brought about in the direction of the axially continuous bore of the piston. The chamber is arranged substantially between the piston and the second end piece and is delimited by an inner wall of the valve housing. 
         [0015]    This solution in accordance with embodiments is advantageous, above all, since the gap between the piston and the second end piece becomes smaller and smaller during filling as the pressure in the tank increases, as a result of which the flow channel is narrowed. Embodiments achieve an enhanced filling degree, since the flow channel makes optimum throughflow of the gaseous medium possible until the valve closes. 
         [0016]    The shut-off valve is suitable, in particular, for media such as hydrogen, methane, natural gas or a mixture of hydrogen and natural gas. The use of other types of liquid media, such as, for example, liquid petroleum gas (LPG), is also suitable as a result of a modification of the shut-off valve in accordance with embodiments. 
         [0017]    The result is a purely mechanical shut-off valve which closes the passage opening sealingly above a defined pressure on account of a set/predetermined spring force and opens neither in the case of a further pressure increase nor a pressure decrease down to a vacuum in the feed opening and therefore always remains closed. The removal of medium takes place at one or more different locations in the pressure accumulator system. 
         [0018]    In accordance with embodiments, a bulge is arranged on the first end side of the second end piece. The bulge is to cause a rapid deflection of the gaseous medium in the direction of the axially continuous bore of the piston. 
         [0019]    In accordance with embodiments, the first end piece and/or the second end piece are/is separate components. The first end piece and/or the second end piece are/is fastened to the valve housing. The fastening to the valve housing may take place by way of a suitable known method such as, for example adhesive bonding, brazing, welding, pressing or screwing. 
         [0020]    In accordance with embodiments, the first end piece is arranged so as to lie opposite the second end piece. As a result of this arrangement, the valve housing may be of particularly compact and simple configuration. 
         [0021]    In accordance with embodiments, the bulge of the second end piece is configured so as to be substantially coaxial with the centre axis of the axially continuous bore of the piston. This ensures that the flow of the gaseous medium takes place in an optimum manner, in particular if the individual components of the shut-off valve are configured as rotational parts. It is also prevented in this way that, in the closed state of the shut-off valve, the bulge of the second end piece may come into contact with the piston, since the bulge protrudes into the axially continuous bore of the piston. 
         [0022]    The bulge of the second end piece may be configured as a point having substantially the shape or cross-section of a cylindrical cone or truncated cone. The maximum diameter, or at least the mean diameter of the bulge of the second end piece may be less than the diameter of the axially continuous bore of the piston. This ensures that the gaseous medium may flow with a low or otherwise reduced flow resistance into the axially continuous bore of the piston. 
         [0023]    In accordance with embodiments, the first end side of the second end piece has a radially circumferential, approximately concave formation. The radially circumferential, approximately concave formation is to form a running transition with the point. As a result of this geometric refinement, the gaseous medium is directed particularly rapidly and efficiently into the axially continuous bore of the piston. 
         [0024]    In accordance with embodiments, the radially outwardly leading bores of the second end piece together have a cross-section which corresponds at least to the cross-section of the inlet opening of the second end piece. This ensures that no throttling or back pressure of the flow of the gaseous medium may occur on account of an excessively small cross-section. 
         [0025]    In a further inventive embodiment, the valve housing has a first end side in the cavity, which first end side has a radially circumferential, approximately concave formation, the radially circumferential, concave formation extending between the inner wall of the valve housing and the cavity. As a result, the gaseous medium is deflected more rapidly in the direction of the bulge of the second end piece. 
         [0026]    In accordance with embodiments, the radially outwardly leading bores of the second end piece are arranged offset tangentially with respect to the centre axis of the inlet opening of the second end piece. By way of the tangential offset, the outflowing gaseous medium is intended to have a swirl imparted to it, as a result of which the flow stream may be aided further. This is advantageous, above all, since the gap between the piston and the second end piece becomes smaller and smaller and therefore the flow channel is narrowed as the pressure rises. 
         [0027]    In accordance with embodiments, an elastic element is arranged between a second end side of the piston and a second end side of the housing valve. The second end side of the piston may be configured as an end side of a collar of the piston. The collar is arranged between the first sliding face of the piston and the second sliding face of the piston. The second end face of the piston, or of the collar of the piston, faces the second sliding face of the piston. The second end side of the valve housing faces away from the first end side of the valve housing and faces the second end side of the piston. 
         [0028]    In accordance with embodiments, at least one disc spring may be used as elastic element. Disc springs afford the advantage that relatively high forces may be transmitted in a relatively small installation space. The elastic element is configured in such a way that it prestresses the piston against an end side of the first end piece in the pressureless state. The elastic element may comprise a disc spring assembly which applies a spring force, in order to press the piston against the first end wall of the first end piece. This ensures that the gap or the chamber between the first end side of the piston and the first end side of the second end piece and therefore the flow channel are as large as possible and the gaseous medium may flow into the tank in an unimpeded manner until filling is ended. As a result, vibrations are also avoided in the valve housing. 
         [0029]    In accordance with embodiments, at least one first seal element is arranged between a first sliding face of the piston and the valve housing. The at least one first seal element may be arranged in the region between the first end side and the second end side of the valve housing. The at least one first seal element is configured in such a way so as to withstand the high pressure which occurs at the inlet opening of the second end piece during filling. Furthermore, the at least one first seal element is configured in such a way that the piston may slide axially on the at least one seal element. At the same time, the at least one first seal element serves as a mounting of the piston. The at least one first seal element is arranged in a groove in the valve housing. The groove is arranged in a region between the first end side and the second end side of the valve housing. 
         [0030]    In accordance with embodiments, at least one second seal element is arranged between a second sliding face of the piston and the first end piece. The at least one second seal element is arranged in the region between the end side of the first end piece and the collar of the piston. The at least one second seal element is likewise configured in such a way that the piston may firstly slide axially and is secondly mounted by the at least one seal element. Since a similarly high pressure occurs at the outlet opening of the first end piece in the case of a fully filled tank as at the inlet opening of the second end piece during filling, the at least one second seal element likewise has to be configured in such a way that it may withstand the high pressure. The at least one second seal element is arranged in a groove in the first end piece. 
         [0031]    In accordance with embodiments, at least one third seal element is arranged between the second end piece and the valve housing. The at least one third seal element seals radially against a second end side of the second end piece on a third end side in the region of the internal thread of the valve housing. A radially circumferential groove is configured in the second end side of the second end piece, in which groove the at least one third seal element is arranged. 
         [0032]    In accordance with embodiments, the first end piece and the second end piece are fastened to the valve housing by way of screwing. The first end piece and the second end piece are preferably screwed at the ends of the valve housing in each case to the internal threads which are provided for this purpose. The screwing connection affords the advantage that the shut-off valve is connected releasably. For example, the components which are arranged in the shut-off valve may therefore be exchanged, such as springs, seal elements and pistons. In addition, it is possible in a simple way to preset the prestressing force of the spring element, by way of the screwing-in depth of the first end piece into the valve housing, to a desired force which is intended to permit the piston to lift up from the end side of the first end piece only when a defined pressure is reached in the outlet opening during filling. As a result, the tank which is fluidically connected to the shut-off valve, may be filled only as far as a pressure which is defined by the previously set spring force and the shut-off valve may always be held closed reliably even without electric devices, such as, for example, actuators. 
         [0033]    In accordance with embodiments, in order that the gaseous medium may be guided into the tank as quickly as possible, the centre axis of the outlet opening of the first end piece is configured so as to be coaxial with the centre axis of the axially continuous bore of the piston. 
         [0034]    In accordance with embodiments, the axially continuous bore of the piston has a diameter which is less than the diameter of the outlet opening of the first end piece. 
         [0035]    In accordance with embodiments, an annular face is formed on a third end side of the piston, the third end side of the piston facing the first end side of the first end piece. The annular face is defined by the diameter of the axially continuous bore of the piston and the diameter of the outlet opening of the first end piece and is designed depending on the spring force of the elastic element in such a way that, when a predetermined pressure of from 90 to 95% of the shut-off pressure of the tank is reached at the outlet opening of the first end piece, the piston lifts off from the end side of the first end piece, as a result of which the entire surface area of the third end side of the piston becomes active, and the piston is rapidly displaced axially in the direction of the first end side of the second end piece. 
         [0036]    The shut-off pressure is defined by the maximum permissible operating pressure of the tank. The shut-off pressure is necessary, in order to prevent damage of the tank or the tank system. 
         [0037]    The difference in surface area of the first end side of the piston with respect to the third end side of the piston, the surface area of the third end side of the piston being greater than the surface area of the first end side of the piston, ensures that the shut-off valve remains closed even when the pressure at the inlet opening rises above the shut-off pressure. The shut-off valve remains closed even when the pressure at the inlet opening drops below the shut-off pressure, since the closing force is determined substantially only by the pressure in the tank on the third end face of the piston, minus the force of the disc spring assembly. 
         [0038]    In accordance with embodiments, the piston has a first end side, the end side preferably forming a sealing edge. The sealing edge is one which is at least approximately the external diameter of the first end side of the piston. It is particularly advantageous if the sealing edge lies completely on the outer radius of the first end side of the piston, since in this case no additional forces which are induced by the valve inlet pressure may act on the piston in the closed state of the shut-off valve. This ensures that the gaseous medium, on account of the swirl which is imparted by the formation of the flow guiding device, still achieves a sufficient flow even in the case of a very small gap between the sealing edge of the piston and the end side of the second end piece. The sealing edge may be produced from a different material to the piston. 
     
    
     
       DRAWINGS 
         [0039]    Embodiments will be illustrated by way of example in the drawings and explained in the description below. 
           [0040]      FIG. 1  illustrates a sectional view of a shut-off valve, in accordance with embodiments. 
           [0041]      FIG. 2  illustrates a sectional view along A 1 -A 1  of radially outwardly arranged bores of the shut-off valve, in accordance with embodiments. 
           [0042]      FIG. 3  illustrates a sectional view along A 2 -A 2  of the radially outwardly arranged bores of the shut-off valve, in accordance with embodiments. 
       
    
    
     DESCRIPTION 
       [0043]      FIG. 1  illustrates a sectional view through a shut-off valve  1  in accordance with the invention. The shut-off valve  1  comprises substantially a valve housing  11 , an axially displaceable piston  12 , a first end piece  13  and a second end piece  14 . The first end piece  13  and the second end piece  14  are mechanically connected to the valve housing  11 , such as, for example, being screwed into the valve housing  11 . The first end piece  13  has an external thread which may be screwed to the internal thread of the valve housing  11 . Furthermore, the first end piece  13  has an internal thread, by way of which the said first end piece  13  may be connected to a tank (not illustrated). The internal thread is fluidically-connected to the outlet opening  13 . 1  of the first end piece  13 . The first end piece has a groove  13 . 2 , in which at least one first seal element  15  is arranged. 
         [0044]    The piston  12  is arranged in the valve housing  11  and is mounted by the at least one first seal element  15  on a first sliding face  12 . 1  which is configured as a sealing face. The second end piece  14  likewise has an external thread, by way of which it may be screwed to the valve housing  11 . An external thread is provided for connection to the filling system or to corresponding pipelines (not illustrated). At least one second seal element  16  is arranged in a second end side  14 . 8  of the second end piece  14  in a first radially circumferential groove  14 . 1 . A second radially circumferential groove  14 . 2  which is likewise configured on a third end side  14 . 9  of the second end piece  14  serves to receive a further seal element (not illustrated). The second end piece  14  has an inlet opening  14 . 3 , through which a gaseous medium may flow from the tank system in the direction of the tank during filling. 
         [0045]    The inflowing gas enters into a chamber K through a flow guiding device S having radially outwardly arranged bores  14 . 4 . The radially outwardly arranged bores  14 . 4  of the second end piece  14 , the chamber K, and a bulge  14 . 5  arranged on the first end side  14 . 7  of the second end piece  14 , the bulge  14 . 5  of the second end piece  14  defining the shape of a point. Furthermore, the flow guiding device S comprises a first end side  11 . 4  in the valve housing  11 , the first end side  11 . 4  in the valve housing  11  having a radially circumferential, concave formation  11 . 1  which extends from the inner wall of the valve housing  11  in the direction of the cavity of the valve housing  11 , and a radially circumferential, concave formation  14 . 6  on the first end side  14 . 7  of the second end piece  14 , the radially circumferential, concave formation  14 . 6  forming a running transition with the bulge  14 . 5  of the second end piece  14 . 
         [0046]    As a result of the above-described flow guiding device S, the gaseous medium flows particularly advantageously in the direction of the axially continuous bore  12 . 2  of the piston  12 . This is advantageous when the gap, and therefore, the chamber K are reduced in size when the piston  12  is displaced in the direction of the first end side  14 . 7  of the second end piece  14 , since the gaseous medium may flow almost without flow losses into the axially continuous bore  12 . 2  of the piston  12  as a result of the deflections of the radial circumferential, concave formations  11 . 1 ,  14 . 6 . 
         [0047]    An at least third seal element  17  serves to seal between the valve housing  11  and a second sliding face  12 . 3  of the piston  12 . The at least third seal element  17  is arranged in a groove  11 . 3 , the groove  11 . 3  being arranged in the region between the first end side  11 . 4  and second end side  11 . 5  of the valve housing  11  formed in the cavity. Furthermore, the second at least one seal element  17  serves to mount the piston  12  in the valve housing  11 . 
         [0048]    The piston  12  has a collar  12 . 4 , the collar being arranged between the first sliding face  12 . 1  and the second sliding face  12 . 3  of the piston. The collar  12 . 4  has a second end side  12 . 6  of the piston, which second end side  12 . 6  faces the second end side  11 . 5  of the valve housing  11 . 
         [0049]    An elastic element  18  is arranged in the cavity of the valve housing  11 , the elastic element  18 , may comprise a disc spring assembly. Ideally, the overlap of the surface areas of the first end side  13 . 4  of the first end piece  13  and the third end face of the piston  12 . 7  in accordance with the diameter of the axially continuous bore  12 . 2  and the diameter of the outlet opening  13 . 1  and the spring force which is set is such that the piston lifts upwardly when the pressure at the outlet opening  13 . 1  of the first end piece  13  has reached from 90 to 95% of the pressure at the inlet opening  14 . 3  of the second end piece  14 . 
         [0050]    Since the annular face  13 . 3  is increased to the diameter of the first sliding face  12 . 1  of the piston  12  after the piston  12  has lifted off from the first end side  13 . 4  of the first end piece  13 , the piston  12  is displaced relatively rapidly in the direction of the first end side  14 . 7  of the second end piece  14  until the piston  12  seals against the first end side  14 . 7  of the second end piece  14  and interrupts the flow of the gaseous medium. The sealing takes place via the first end side  12 . 5  of the piston  12 , which first end side  12 . 5  forms a sealing edge. The sealing edge is a substantially outwardly radially circumferential edge of the first end side  12 . 5  of the piston  12 . The radially circumferential edge of the piston  12  may have a bevelled or rounded portion, for example, in the region of the first end side  12 . 5  of the piston  12 . 
         [0051]    A ventilation bore  11 . 2  is provided in the valve housing  11  in the region of the elastic element  18 , which ventilation bore  11 . 2  permits pressure equalization of the air in the valve housing  11  between the two at least one first and third seal elements  15  and  17  when the piston  12  is displaced axially. 
         [0052]      FIGS. 2 and 3  are a section A 1 -A 1  and A 2 -A 2 , respectively, through the radially outwardly arranged bores  14 . 4  of the second end piece. 
         [0053]    In  FIG. 2 , the radially outwardly arranged bores  14 . 4  are arranged centrally with respect to the centre axis of the inlet opening  14 . 3  of the second end piece  14 . In  FIG. 3 , the radially outwardly arranged bores  14 . 4  of the second end piece  14  are arranged tangentially with respect to the centre axis of the inlet opening  14 . 3  of the second end piece  14 . As a result, the gaseous medium has swirl imparted to it, as a result of which the gaseous medium is directed more rapidly in the direction of the axially continuous bore  12 . 2  of the piston  12 , whereby an enhanced flow behaviour is achieved. 
         [0054]    The term “coupled” or “connected” may be used herein to refer to any type of relationship, direct or indirect, between the components in question, and may apply to electrical, mechanical, fluid, optical, electromagnetic, electromechanical or other connections. In addition, the terms “first,” “second,” etc. are used herein only to facilitate discussion, and carry no particular temporal or chronological significance unless otherwise indicated. 
         [0055]    Those skilled in the art will appreciate from the foregoing description that the broad techniques of the embodiments may be implemented in a variety of forms. Therefore, while the embodiments have been described in connection with particular examples thereof, the true scope of the embodiments should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims. 
       LIST OF REFERENCE SIGNS 
       [0000]    
       
         
           
               1  Shut-off valve 
               11  Valve housing 
               11 . 1  Radially circumferential, concave formation 
               11 . 2  Ventilation bore 
               11 . 3  Groove 
               11 . 4  First end side 
               11 . 5  Second end side 
               11 . 6  Third end side 
               12  Piston 
               12 . 1  First sliding face 
               12 . 2  Axially continuous bore 
               12 . 3  Second sliding face 
               12 . 4  Collar 
               12 . 5  First end side 
               12 . 6  Second end side 
               12 . 7  Third end side 
               13  First end piece 
               13 . 1  Outlet opening 
               13 . 2  Groove 
               13 . 3  Annular face 
               13 . 4  First end side 
               14  Second end piece 
               14 . 1  Groove 
               14 . 2  Groove 
               14 . 3  Inlet opening 
               14 . 4  Radially arranged bores 
               14 . 5  Bulge 
               14 . 6  Radially circumferential, concave formation 
               14 . 7  First end side 
               14 . 8  Second end side 
               14 . 9  Third end side 
               15  First seal element 
               16  Second seal element 
               17  Third seal element 
               18  Elastic element 
             K Chamber 
             S Flow guiding device