Abstract:
A pressurized storage tank arrangement having at least two pressurized storage tanks, the at least two pressurized storage tanks being configured for connection to one another in a fluid-conducting manner via a connecting device. The at least two pressurized storage tanks are configured for connection to the connecting device in a fluid-conducting manner at a first and a second connecting section.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. §119 to European Patent Application No. EP 12163772.2 (filed on Apr. 11, 2012), which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     Embodiments are directed to a pressurized storage tank arrangement having at least two pressurized storage tanks, the at least two pressurized storage tanks configured for connection to one another in a fluid-conducting manner via a connecting device. 
     BACKGROUND 
     Pressurized storage tanks are used to hold pressurized fluids. In particular, pressurized storage tanks are used as fuel tanks for vehicles and then contain gases, e.g. CNG, mixed gases or hydrogen, or liquids such as LPG or LNG at high pressures. The pressurized storage tanks are usually produced as cylinders. Another known practice is to combine a plurality of pressurized storage tanks in a module. It is thereby possible to provide joint access to a plurality of pressurized storage tanks. 
     A fuel tank arrangement for storing pressurized gases for a motor vehicle having a plurality of individual fuel tanks, each with an end opening for the filling and emptying of the tank, which furthermore has a header and a holding part. The fuel tanks are configured for connection, on the one hand, to the header by way of their openings and, on the other hand, mechanically to the holding part. Hence, the individual fuel tanks bound together into a unit by the header and the holding part, is known from DE 20 2006 004 434 U1. 
     DE 102 06 502 C1 has furthermore disclosed a pressurized gas tank system having at least two gas containers of substantially the same kind, wherein the gas containers have a bottom part and a removal part and openings are associated with the removal parts. The removal parts are associated with a shutoff valve, and the removal parts protrude by way of the openings thereof into a connecting rail which connects the removal parts to one another. The openings are connected to a gas duct extending in the connecting rail, with the connecting rail being associated with a shutoff valve at a gas duct outlet and said valve forming the shutoff valve common to all the gas containers. 
     DE 198 12 904 A1 has disclosed a device for storing compressed gas, having a multiplicity of storage tanks, wherein each storage tank has a header and the respective headers are connected or may be connected to one another in a modular manner. The compressed gas is carried out of the storage tanks via a flow duct, which is provided in the headers and which communicates via a bore with the cavity of the respective storage tanks. The individual headers are connected by way of connecting elements, which are inserted into corresponding openings in the headers. 
     SUMMARY 
     Embodiments are directed to an enhanced pressurized storage tank arrangements of the type stated and, in particular, to provide a pressurized storage tank arrangement that has a very flexible structure and provides advantageous conditions for movement of fluid within the arrangement. 
     In accordance with embodiments, a pressurized storage tank arrangement having at least two pressurized storage tanks is provided, the at least two pressurized storage tanks configured for connection to one another in a fluid-conducting manner via a connecting device. The at least two pressurized storage tanks are configured for connection to the connecting device in a fluid-conducting manner at a first and a second connecting section. 
     In accordance with embodiments, the pressurized storage tanks are thus configured for connection to one another at at least two connection points, e.g., at opposite ends of cylindrical pressurized storage tanks via the connecting device. This advantageously allows a very wide variety of fluid flow configurations within the arrangement, in particular also circular flows, since it is possible for an inflow of fluid into a pressurized storage tank and an outflow within the pressurized storage tank arrangement to take place simultaneously. The pressurized storage tanks communicate via a separate second duct, e.g., during the filling thereof and during the removal of the fluid. Among other things, this advantageously also allows a simplified purging operation. 
     A purging operation is necessary, for example, if a test fluid which does not correspond to the medium stored during the actual use of the pressurized storage tanks is used during a final test on the leaktightness of the overall system, or if filling with, for example, hydrogen, for the transportation of the pressurized tank arrangement is dispensed with for reasons of safety. For hydrogen storage systems, helium or nitrogen are usually used as test fluids, but these may cause damage to the drive unit in use in the vehicle. 
     By virtue of the connecting arrangement in accordance with embodiments, the free communication between all the components and the possibility of elements that influence flow, such as reductions in cross section, it is advantageously possible to implement a purging operation which saves time, energy and resources during commissioning in the vehicle. This is achieved, for example, by introducing the fluid that is ultimately to be stored via a filling valve unit while the test fluid is being discharged or extracted by suction in a controlled manner at a removal valve unit. If purging has been carried out with a quantity corresponding to the total volume of the system, a high level of cleanliness in the system is achieved through the controlled flow through all the components. One major advantage is that this is achieved even with a very low pressure. Advantageously, no filling with test fluid under a high pressure, with time-consuming discharge and periodic repetition of the operation is thus required. 
     In accordance with embodiments, the first connecting sections of the pressurized storage tanks are configured for connection to a first connecting element of the connecting device and the second connecting sections of the pressurized storage tanks are configured for connection to a second connecting element of the connecting device. The first connecting element and the second connecting element being configured for connection to one another in a fluid-conducting manner exclusively via the pressurized storage tanks. 
     In accordance with embodiments, the connecting device is formed by two separate connecting elements, with one connecting element connecting the two first sections or ends of the pressurized storage tanks to one another, and the second connecting element connecting the two second sections or ends of the pressurized storage tanks to one another. 
     In accordance with embodiments, the connecting device is of mechanically stable design. If the connecting device is made up of connecting elements, as described hereinabove, the individual connecting elements are preferably embodied in a mechanically stable way. The connecting device or the connecting elements thus form a stable frame, which is used to accommodate pressurized storage tanks. 
     In accordance with embodiments, the connecting elements may form a mechanically stable frame together with pressurized storage tanks of elongate shape, e.g., cylindrical pressurized storage tanks, the two mutually opposite ends of the pressurized storage tanks being configured for connection in a fluid-conducting manner to the respective connecting elements. 
     In accordance with embodiments, fastening points for the fastening of the pressurized storage tank arrangement, in particular in a motor vehicle, are formed exclusively on the connecting device. The overall pressurized storage tank arrangement is accordingly installed by way of the connecting device. Flexible elements, such as rubber mounts, may be integrated at the fastening points, e.g., the suspension or mounting receptacles of the connecting device. By way of said elements, it is possible to accommodate changes in length and changes in the position of the pressurized storage tanks. In this arrangement, changes in the length of the pressurized storage tanks generally occur in a uniform manner owing to the simultaneous pressure build-up or reduction via the connecting sections and the connecting device, through the communicating ducts, thus reducing the flexibility required for this purpose. 
     In accordance with embodiments, valves and/or valve blocks and/or filters and/or shutoff elements and/or pressure reducers and/or reductions in cross section, in particular, a filling valve unit and/or a removal valve unit, are arranged in or on the connecting device. Components which serve to influence the fluid flow are thus advantageously arranged in the connecting device and may be distributed in a flexible manner throughout the connecting device. 
     In accordance with embodiments, the pressurized storage tanks are configured for connection inseparably to the connecting device. This results in making it only possible to separate a pressurized storage tank from the connecting device by destroying a seal and/or by way of a special tool. This makes it possible to check, even retrospectively, whether the end user has attempted to break the connection between a pressurized storage tank and the connecting device. This is intended to ensure that work on the connection is carried out only by trained personnel or specialist workshops. 
     In accordance with embodiments, the pressurized storage tanks are configured for connection to the connecting device mechanically by way of a fixed screwed joint, in particular, by way of a banjo bolt. 
     In accordance with embodiments, at least one pressurized storage tank and the connecting device may be configured for connection to one another in a fluid-conducting manner, the pressurized storage tank having a transverse bore on a first connecting section, the bore intersecting an axial bore of the pressurized storage tank, the transverse bore being configured for connection in a fluid-conducting manner to the connecting device. An axial bore is provided in a connecting section in the pressurized storage tank. The axial bore is intersected by a transverse bore. The transverse bore is preferably normal to the axial bore and is thus arranged parallel to the boundary wall of the pressurized storage tank in the connecting section. The transverse bore may therefore be configured for connection easily and reliably to bores of a connecting device that are likewise transverse to the pressurized storage tanks, in particular, may be configured for connection by way of a plug-in joint. 
     In accordance with embodiments, the term “bore” is intended to mean any elongate opening in a surrounding body. As a result, the production method for the opening is not defined. Apart from producing the opening by boring, other methods are therefore also included, e.g. the deformation of a profile. 
     Sealing rings for sealing between the pressurized storage tank and the connecting device are preferably installed on the first connecting section of the pressurized storage tank, on both sides of the transverse bore. 
     In accordance with embodiments, the first connecting section of the pressurized storage tank is configured for connection to the connecting device by way of a plug-in joint or clamp joint or snap joint. This advantageously makes possible rapid mounting and, depending on the embodiment, also rapid removal of the pressurized storage tank. One possibility for this purpose is, for example, to provide an accessible socket for a fitting and removal tool or a bore for removal. 
     The plug-in joint is preferably designed as a spring element, in particular, as a retaining ring, crescent-shaped retaining ring, bolt or screw, in the connecting section, said element coming to rest in a groove in the connecting device. 
     In accordance with embodiments, an axial clearance for movement for the plug-in joint, in particular, for the spring element, is formed, in particular a space for movement in a groove in the connecting device. A defined play in the groove is thereby allowed for the plug-in joint in the event of changes in the length of the pressurized storage tank. 
     The connecting device is preferably mounted in a vehicle and is used to support the pressurized storage tanks. The connecting device thus forms a stable frame, which is pre-installed in a vehicle. The individual pressurized storage tanks are inserted into this frame and may move in the frame in accordance with the predetermined range of movement. 
     In accordance with embodiments, the first connecting section of the pressurized storage tank is configured for connection to the connecting device by way of a screwed joint. For this purpose, use is made, in particular, of a screw, a screw nut and/or a cotter. 
     A pressurized storage tank component, in particular a valve, is preferably arranged in the axial bore of the pressurized storage tank. 
     In accordance with embodiments, the connecting device has an opening in the region of the axial bore of the pressurized storage tank. As a result, a pressurized storage tank component arranged in the axial bore, in particular, is easily accessible from the outside. 
     In accordance with embodiments, the opening may furthermore be covered by way of a cover, it being advantageously possible for the cover to be designed, in particular, as an indicator for the state of leaktightness of the pressurized storage tank. The cover prevents the ingress of dirt into the opening. Moreover, the cover may be embodied in such a way that non-destructive removal of the pressurized storage tank is not allowed and/or unauthorized access is evident. Moreover, the cover may be embodied in such a way that, if there is damage to the seal, the cover is arched outwards, for example, or tears, thus allowing the damage to the seal to be recognized in time. 
     In accordance with embodiments, the pressurized storage tank has a predetermined breaking point in the first connecting section, with a flow limiter also being arranged, in particular in the pressurized storage tank. The predetermined breaking point is arranged in such a way relative to the flow limiter that the flow limiter remains in the pressurized storage tank when there is a break at the predetermined breaking point. 
     In accordance with embodiments, the pressurized storage tank has a second connecting section, which is configured for connection in a fluid-conducting manner to the connecting device. The second connecting section is, in particular, of identical construction to the first connecting section. The pressurized storage tank may thus be configured for connection to the connecting device at two sections, in particular at both ends of a cylindrical pressurized storage tank, by way of a connection in accordance with embodiments. 
    
    
     
       DRAWINGS 
       Embodiments are described by way of example below with reference to the drawings. 
         FIG. 1   a  is a front view schematic illustration of a pressurized storage tank arrangement in accordance with embodiments. 
         FIG. 1   b  is a top view schematic illustration of a pressurized storage tank arrangement in accordance with embodiments. 
         FIG. 2   a  is a front view schematic illustration of a pressurized storage tank arrangement in accordance with embodiments. 
         FIG. 2   b  is a top view schematic illustration of a pressurized storage tank arrangement in accordance with embodiments. 
         FIG. 3  to  FIG. 7  are front view schematic illustrations of a connection between the pressurized storage tank and the connecting device in accordance with embodiments. 
         FIG. 8  is a top view schematic illustration of a connection between the pressurized storage tank and the connecting device in accordance with embodiments. 
         FIG. 9  is a top view schematic illustration of a connection between the pressurized storage tank and the connecting device in accordance with embodiments. 
     
    
    
     DESCRIPTION 
     In  FIGS. 1   a  to  2   b , schematic illustrations of various pressurized storage tank arrangements in accordance with embodiments are illustrated. 
     The pressurized storage tank arrangement  10  includes cylindrical pressurized storage tanks  11 , which are permanently connected at both ends thereof to connecting elements of a connecting device  31 . The pressurized fluid flows out of the pressurized storage tanks  11  through bores  32  in the connecting elements. The connecting device  31  is of mechanically stable design and is connected at fastening points  41 ,  42  in such a way as to be suspended or to stand, e.g., in a vehicle. The pressurized storage tanks  11  are configured for connection to the connecting device  31  by way of screwed joints  50 . A temperature-controlled pressure reducer  21 , an automatic cylinder valve  23  and a maintenance valve  24  are integrated into or onto the connecting device  31 , as are valve blocks  12 ,  22 . Valves, valve blocks and the like may be mounted at any point in or on the connecting device  31 . 
     Moreover, reductions in cross section  37  are arranged in the connecting device  31 . Selective routing of the flow circulation in the overall system is possible through the arrangement of the cited components as desired in the connecting device and through the free communication between the pressurized storage tanks  11  via the connecting device  31 . Through the arrangement as desired of the filling valve unit  33  and of the removal valve unit  34  in the pressurized storage tank arrangement  10 , in particular, simple purging of the overall system during commissioning is thus made possible. A mechanically strong connection between the pressurized storage tanks  11  and the connecting device  31  is accomplished by way of a screwed joint  50 , for example, and is illustrated in detail in  FIG. 3 . 
       FIG. 3  is a schematic illustration of a connection between pressurized storage tanks  11  and connecting device  31 . For connection, use is made of a banjo bolt  51 , which is secured on the pressurized storage tank  11  by way of an external thread  52 . The internal thread  53  of the banjo bolt  51  is used to accommodate valves and/or filters that are close to the cylinder. Other types of fastening are also possible, however. Thus, the valves and/or filters close to the cylinder may be fixed using grooves  54  in the banjo bolt  51  by way of a retaining ring, for example. 
       FIGS. 4 to 7  are schematic illustrations of further embodiments of the connection between the pressurized storage tank and the connecting device from the front. 
     In  FIG. 4 , the connection between the pressurized storage tank  11  or a connecting section of the pressurized storage tank  11  and the connecting device  31  or a connection block of the connecting device  31  is embodied as a clamp joint or plug-in joint. Clamping is accomplished by way of a clamp connecting element  122 , which is embodied as a crescent-shaped retaining ring and which is fixed in a groove in the connecting device  31 . In this case, the groove has a clearance  124  in the axial direction for movement of the retaining ring. 
     In the connecting section of the pressurized storage tank  11 , an axial bore  112  leads out of the interior of the pressurized storage tank  11  in the direction of an outer boundary of the connecting section of the pressurized storage tank  11 . This axial bore  112  is intersected by a transverse bore  111 , allowing a fluid flow to be carried onward from the axial bore  112  via the transverse bore  111 . The transverse bore  111  extends as far as the end of the connecting section of the pressurized storage tank  11 , and therefore, a connection between the interior of the pressurized storage tank  11  and the surroundings of the pressurized storage tank  11  is established via the transverse bore  111 . Thus, fluid may thus pass into the pressurized storage tank  11  and may emerge from the storage tank  11  via the transverse bore  111 . The transverse bore  111  is aligned in such a way that it opens into bore  32  in the connecting device. This alignment of the bores  111  and  32  relative to one another is facilitated particularly by the plug-in joint, in contrast especially to screwed joints. 
     Moreover, the radial alignment of the pressurized storage tank  11  may be secured by way of the centring feature  129 , e.g. a centring pin. Sealing rings  130  and  131  are arranged on both sides of the transverse bore  111 , between the connecting section of the pressurized storage tank  11  and the connection block of the connecting device  31 . 
     In the embodiment illustrated in  FIG. 5 , the connection between the pressurized storage tank  11  and the connecting device  31  is secured by way of a nut  118 . 
     In the embodiment illustrated in  FIG. 6 , the connection between the pressurized storage tank  11  and the connecting device  31  is established by way of a screwed connecting element  123 , but the connection could also be embodied as a plug-in joint. The connection likewise uses centring features  129 . In this embodiment, the axial bore  112  is continuous, being embodied as a through opening. 
     Moreover, the connecting device  31  also has an opening  125  in the region of the open end of the axial bore  112 , allowing components such as a manual valve, for example, to be screwed or plugged into the opening. In the opening of the axial bore  112  there is a screw  132 , which, when positioned in the same plane as the pressurized storage tank  11 , seals off the opening from the outside and exposes the bores  111 ,  112 , or, when fully screwed in, seals off the axial bore  112  from the transverse bore  111 . In a defined state of the screw  132 , it exposes an additional opening  133  to the outside. The additional opening  133  is designed in such a way that a service line, for example, may be screwed in. The opening  125  may be covered by way of a cover  140  made of plastic or sheet metal, said cover being embodied in such a way that it is arched outwards or tears if there is damage to the seal, in particular to the sealing ring  130 . The cover  140  is furthermore embodied in such a way that non-destructive removal is not possible and hence unauthorized access is prevented or is evident. 
     In the embodiment illustrated in  FIG. 7 , the connecting section of the pressurized storage tank  11  additionally has a predetermined breaking point  116  and a flow limiter  113 , which are arranged in such a way that the flow limiter  113  remains in the pressurized storage tank  11  when there is a break at the predetermined breaking point  116 . The axial bore  112  is embodied in such a way that a flow limiter  113  and/or a filter  114  and/or a sealing seat  115  may be screwed in or plugged in. 
       FIG. 8  illustrates a schematic illustration of a design of the connection between the pressurized storage tank and the connecting device from above. In this case, bolts are arranged as clamp connecting elements  122  in bores  126  which overlap with the groove in the pressurized storage tank  11 . This embodiment is configured in such a way that rapid mounting and rapid removal are made possible by way of the accessible socket  127  for the fixing and removal tool and the bore  128 . 
       FIG. 9  illustrates a schematic illustration of another embodiment of the connection between the pressurized storage tank  11  and the connecting device  31  from above. In this case, screws are used as screwed connecting elements  123 , the thread of said screws being formed along only part of the length of the screw. The front part of the connecting elements  123 , which ensures that the pressurized storage tank  11  is retained on the connecting device  31 , is embodied as an unthreaded stud. Given appropriate dimensioning of the groove, freedom of movement for the connecting element  123  is thereby ensured, and hence play is allowed for the pressurized storage tank  11  mounted in the connecting device  31 . Seals  141 ,  142  are visible on the screwed connecting elements  123 . These seals may be provided by way of paint or spot welds, for example. 
     Embodiments are directed to a pressurized storage tank arrangement that has a highly flexible structure and provides advantageous conditions for movement of fluid within the arrangement. 
     Although embodiments have been described herein, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art. 
     LIST OF REFERENCE SIGNS 
       10  pressurized storage tank arrangement 
       11  pressurized storage tank 
       12  valve block 
       21  pressure reducer 
       22  valve block 
       23  cylinder valve 
       24  maintenance valve 
       31  connecting device 
       32  bore 
       33  filling valve unit 
       34  removal valve unit 
       37  reductions in cross section 
       41  fastening point, suspended embodiment 
       42  fastening point, standing embodiment 
       43  rubber mount 
       50  screwed joint 
       51  banjo bolt 
       52  external thread 
       53  internal thread 
       54  internal groove 
       111  transverse bore 
       112  axial bore 
       113  flow limiter 
       114  filter 
       115  sealing seat 
       116  predetermined breaking point 
       118  nut 
       122  clamp connecting element 
       123  screwed connecting element 
       124  clearance for movement 
       125  opening 
       126  bore 
       127  accessible socket 
       128  bore 
       129  centring feature 
       130  sealing ring 
       131  sealing ring 
       132  screw 
       133  opening 
       140  cover 
       141  seal 
       142  seal