Abstract:
Structures for securing a fluid containment cylinder at the neck portion of the cylinder include a mounting frame having a bore disposed therein and a slot disposed orthogonally to the central axis of the bore. The neck of the cylinder passes through the bore and a u-bolt passes through the slot, registering against a shoulder on the neck of the cylinder, thereby securing the cylinder within the block. In other embodiments, the securing structure includes a collar for preventing rotation of the cylinder or for accommodating a certain degree of misalignment of the cylinder with respect to the securement structure.

Description:
[0001]    This application claims priority to U.S. Provisional Patent Application Serial No. 60/388,911, filed Jun. 14, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to fluid storage, and specifically to a method and apparatus for mounting a fluid containment vessel.  
           [0003]    In many applications, the qualities of lightweight construction and high resistance to fragmentation and corrosion damage are highly desirable characteristics for a pressure vessel. These design criteria have been met for many years by the development of high pressure composite (fiber reinforced resin matrix) containers; for instance, containers fabricated of laminated layers of wound fiberglass filaments or various types of other synthetic filaments which are bonded together by a thermal-setting or thermoplastic resin. An elastomeric or other non-metal resilient liner or bladder often is disposed within the composite shell to seal the vessel and prevent internal fluids from contacting the composite material.  
           [0004]    Such composite vessels have become commonly used for containing a variety of fluids under pressure, such as storing oxygen, natural gas, nitrogen, rocket or other fuel, propane, etc. The composite construction of the vessels provides numerous advantages such as lightness in weight and resistance to corrosion, fatigue and catastrophic failure. These attributes are due to the high specific strengths of the reinforcing fibers or filaments that typically are oriented in the direction of the principal forces in the construction of the pressure vessels.  
           [0005]    Composite pressure vessels of the character described above originally were developed for aircraft and aerospace applications primarily because of the critical weight restrictions in such vehicles. As compressed natural gas (CNG) has become more widely used in ground-based vehicles such as buses and cars, however, the composite pressure vessel has become more widely used in such vehicles as well.  
           [0006]    The structural requirements of a pressure vessel are such that a generally-cylindrical shape having rounded ends is a highly-desirable form factor from a standpoint of both strength and packing efficiency. Unfortunately, the rounded shape can make securing such a pressure vessel to the vehicle difficult.  
           [0007]    The neck of the compressed gas cylinder provides a structural protrusion suitable for attachment by a collar or similar device. Certain known designs make use of this feature to secure a gas cylinder. Unfortunately, such designs suffer from a number of drawbacks. Certain designs handle misalignment poorly, and can place substantial stresses on the neck structure in the event of misalignment. Certain designs inadequately secure the neck, so that there is an unacceptable risk that the cylinder might work itself free under the right conditions. Finally, certain designs are such that the cylinder can rotate about the principal axis of the cylinder, thereby placing stress on the connection lines or other attached hardware.  
         SUMMARY OF THE INVENTION  
         [0008]    The vessel securement method and apparatus disclosed herein provides a unique combination of structures suitable for safely securing a pressure vessel under a variety of conditions. Using the teachings of the present invention, one of skill in the art will be able to readily construct a pressure vessel mounting scheme suitable for securely fastening a pressure vessel against axial and rotational movement. Further, the teachings of the present invention are suitable for construction of pressure vessel mounting structures able to accommodate a substantial degree of misalignment without unduly stressing the neck of the pressure vessel.  
           [0009]    In one embodiment, the present invention includes a compressed gas cylinder mount incorporating a frame having a top surface, a front surface, a back surface, a neck receiving bore passing through the frame from the front surface to the back surface, and a fastener bore passing through the frame from the top surface to the neck receiving bore. A fastener is disposed within the fastener bore, having a neck receiving end and a threaded end. The neck receiving end has an inner profile suitable for capturing the neck of a compressed gas cylinder. A nut, threadably engaged to the threaded end of the fastener, is used to tighten and secure the assembly.  
           [0010]    In a second embodiment, the invention includes a frame having a neck receiving bore passing through the frame from its front surface to its back surface. The frame has a pair of fastener bores passing through the frame on either side of the neck receiving bore from the bottom surface to the top surface. The neck of the cylinder is secured by a u-bolt, having a neck receiving end and first and second threaded uprights, with each threaded upright disposed within one of the first and second fastener bores. A pair of nuts secure the assembly.  
           [0011]    In a third embodiment, the invention includes a frame having a neck receiving bore passing through the frame from its front surface to its back surface and a fastener bore passing through the frame from its top surface to the neck receiving bore. A fastener is disposed within the fastener bore, having a neck receiving end and a threaded end. The neck receiving end has an inner profile suitable for capturing the neck of a compressed gas cylinder. A nut, threadably engaged to the threaded end of the fastener, secures the assembly.  
           [0012]    In this embodiment, the rotational orientation of the cylinder is fixed using a locating collar disposed on the front surface of the frame around the neck receiving bore. The collar has a first locator receiving feature and a second locator receiving feature. A first locator, disposed in the front surface of the frame, is mated to the first locator receiving feature. A second locator is disposed within the second locator receiving feature and a neck locating feature.  
           [0013]    In a fourth embodiment, the present invention includes a frame having a neck receiving bore passing through the frame from the front surface to the back surface and a spherical inner surface disposed around the neck receiving bore. A spherical bearing, having a spherical outer surface and a cylindrical inner surface, is disposed at least partly within the spherical inner surface of the frame. A retainer, having a spherical inner surface, is disposed against the spherical bearing opposite the mount and secured to the mount, thereby capturing the spherical bearing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    For more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures, in which:  
         [0015]    [0015]FIG. 1 depicts an isometric view of a compressed gas cylinder and mount assembly according to one embodiment of the present invention;  
         [0016]    [0016]FIG. 2 depicts an exploded isometric view of the compressed gas cylinder and mount assembly of FIG. 1;  
         [0017]    [0017]FIG. 3 depicts a front section view of the compressed gas cylinder and mount assembly of FIGS. 1 and 2 taken along line  3 - 3  of FIG. 2;  
         [0018]    [0018]FIG. 4 depicts a bottom section view of a cylinder frame according to certain embodiments of the present invention;  
         [0019]    [0019]FIG. 5 depicts an isometric view of a compressed gas cylinder and mount assembly according to a second embodiment of the present invention;  
         [0020]    [0020]FIG. 6 depicts an exploded isometric view of the compressed gas cylinder of FIG. 5;  
         [0021]    [0021]FIG. 7 depicts an isometric view of a compressed gas cylinder and mount assembly according to a third embodiment of the present invention;  
         [0022]    [0022]FIG. 8 depicts an exploded isometric view of the assembly of FIG. 7;  
         [0023]    [0023]FIG. 9 depicts a side section view of the assembly of FIGS. 7 and 8 taken along line  9 - 9  of FIG. 7;  
         [0024]    [0024]FIG. 10 depicts a section isometric view of a compressed gas cylinder and mount assembly according to a fourth embodiment of the present invention; and  
         [0025]    [0025]FIG. 11 depicts a section isometric view of a compressed gas cylinder and mount assembly according to a fifth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that may be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.  
         [0027]    As seen in FIGS.  1 - 4 , cylinder and mount assembly  100  includes a frame  102  designed to receive a cylinder  104  by the neck  106  of cylinder  104 . In this embodiment, the frame  102  captures neck  106  and fixes it in its axial position by registering against an annular groove  108  in the neck  106 . The securement is accomplished by a fastener  110 , which may be a u-bolt, as shown in FIGS.  1 - 4 . Those of skill in the art will have knowledge of other suitable fasteners. As examples, a j-bolt, an eye-bolt, or a square bend u-bolt could be used in place of the u-bolt shown in FIGS.  1 - 4  without departing from the spirit and scope of the present invention. The fastener  110  could be a plate or subframe, or even a band or strap. As noted, these fastening solutions, and many others, will be known to those of skill in the art.  
         [0028]    In the embodiment shown in FIGS.  1 - 4 , the fastener  110  is held in place by one or more nuts  114  threadably engaged to one or more threaded portions of fastener  110 . As with the type of fastener  110  employed, although a threaded fastener may be preferred for certain embodiments, there is nothing within the spirit and scope of the present invention limiting the fastener  110  to threaded fasteners. Locking pins, elastomeric materials, or friction-based securement mechanisms could be employed. The securement mechanism could make use of plastic deformation of the fastener, or even welding or adhesive bonding of the fastener  110  to the frame  102 , particularly in applications wherein the cylinder  102  is installed permanently. Each of these mechanisms, and many others, are within the spirit and scope of the present invention, as will be appreciated by those of skill in the art. In many applications, it will be necessary that the fastener  110  incorporate some form of tensioning mechanism similar to the operation of the nuts  114  on the threads of the u-bolt in order to solidly secure the neck  106  of the tank  104 .  
         [0029]    The design of frame  102  may vary from one application to another. In the embodiment shown in FIGS.  1 - 4 , the frame  102  has a generally box-like shape, having front, back, top, bottom, and side surfaces. Other shapes will be suitable, depending on application. Frame  102  of FIGS.  1 - 4  receives neck  106  of cylinder  104  through neck receiving bore  118 .  
         [0030]    The fastener  110  passes through fastener bores  112  to the top surface  116  of the frame  102 . As the fastener  110  is tightened against the neck  106  using nuts  114 , the upper surface of the neck  106  is forced against the upper surface of neck receiving bore  118 , thereby securing cylinder  104 .  
         [0031]    [0031]FIG. 5 depicts an isometric view of a compressed gas cylinder and mount assembly according to a second embodiment of the present invention. FIG. 6 depicts an exploded isometric view of the assembly of FIG. 5. As seen in FIGS. 5 and 6, cylinder and mount assembly  200  includes a frame  202  designed to receive a cylinder  204  by the neck  206  of cylinder  204 . In this embodiment, the frame  202  captures neck  206  and fixes it in its axial position by registering against an annular groove  208  in the neck  206 . The securement is accomplished by a fastener  210 , which may be a u-bolt, as shown in FIG. 5. Those of skill in the art will have knowledge of other suitable fasteners, including but not limited to the fasteners specifically described above in connection with fastener  110 . In this embodiment, the fastener  210  is held in place by one or more nuts  214  threadably engaged to one or more threaded portions of fastener  210 . As with fastener  110 , there is nothing within the spirit and scope of the present invention requiring that fastener  210  be a threaded fastener.  
         [0032]    The design of frame  202  may vary from one application to another. In the embodiment shown in FIGS. 5 and 6, the frame  202  has a generally box-like shape, having front, back, top, bottom, and side surfaces. Other shapes will be suitable, depending on application. Frame  202  of FIG. 5 receives neck  206  of cylinder  204  through neck receiving bore  218 .  
         [0033]    The fastener  210  passes through fastener bores  212  to the top surface  216  of the frame  202 . As the fastener  210  is tightened against the neck  206  using nuts  214 , the upper surface of the neck  206  is forced against the upper surface of neck receiving bore  218 , thereby securing cylinder  204 .  
         [0034]    In addition to the mounting structures described above in connection with FIGS. 5 and 6, which are largely identical to the structures described above in connection with FIGS.  1 - 4 , assembly  200  incorporates additional structures for securing cylinder  204  in its rotational orientation. Specifically, assembly  200  incorporates a location collar  220  designed to fix the rotational orientation of the neck  206  to that of the frame  202 .  
         [0035]    In operation, the location collar  220  is disposed about the neck  206  and fixed in its rotational orientation by first locator  222  registering against one of the location grooves  224  in the location collar  220  as well as a locating feature in the frame  202 . In the embodiment depicted in FIG. 5, the first locator  222  is a pin disposed within a pin bore  223  in the frame  202 , but those of skill in the art will appreciate that a wide variety of structures and mechanisms may be suitable for this purpose.  
         [0036]    With the rotational orientation of the location collar  220  fixed by the first locator  222 , the rotational orientation of the neck  206 , and therefore the tank  204 , can be fixed by locating the neck  206  to the location collar  220 . This task is accomplished by second locator  226 , which locates the neck  206  using one of collar-to-neck location grooves  228  and neck axial groove  230  in the neck  206  of the tank  204 .  
         [0037]    In the embodiment shown in FIGS. 5 and 6, the second locator  226  is a pin, but those of skill in the art will recognize that a number of structures are suitable for use in this application. Further, although the locating features shown in FIGS. 5 and 6 are grooves  224 ,  228  and  230 , those of skill in the art will appreciate that locating holes would work in a similar manner, particularly with respect to collar locating grooves  224 .  
         [0038]    In certain embodiments, the spacing of the locating grooves  224  and  228  are such that the orientation of the cylinder  204  can be adjusted with a relatively high degree of precision even with a relatively small number of locating grooves. In one embodiment, the pattern of inner and outer grooves  224  and  228  is such that the cylinder  204  can be fixed in place at any point around a 360-degree angle to a precision of one degree.  
         [0039]    Cylinder and frame assembly  300 , shown in FIGS.  7 - 9 , differs from the embodiments shown in FIGS.  1 - 4  in the use of a spherical bearing  310  in place of the fastener  110  shown and described in those figures. Spherical bearing  310  is disposed around the outer surface of neck  306 . The inner surface  322  of spherical bearing is shaped to mate with the outer surface of the neck  306 . In the embodiment shown in FIGS. 7, 8 and  9 , the inner surface  322  is cylindrical, in order to conform to the cylindrical shape of the neck  306 . Depending on application, spherical bearing  310  may be either fixed or slidable on neck  306 . A slidable design would have the advantage of providing the highest degree of compliance to misalignment, while a fixed design would have the advantage of holding the cylinder more securely. As assembled, spherical bearing  310  seats against a spherical inner surface  316  in the frame  302 . The spherical bearing  310  is captured within frame  302  by securing collar  320 . Securing collar  320  may have a spherical inner surface  324  shaped to seat with the outer surface of spherical bearing  310 . Securing collar  320  may be retained within frame  302  by a number of methods. In the embodiment shown in FIGS.  7 - 9 , securing collar is retained by snap ring  330 , but other methods of securement, including but not limited to a threaded engagement, may be employed.  
         [0040]    Using this arrangement, a certain degree of axial misalignment can be tolerated by the assembly without placing potentially harmful stresses on the neck  306  of the cylinder  304 . In certain embodiments, assembly  300  may incorporate one or more features similar to locating collar  220 , described above, to fix the rotational location of the cylinder  304  while still allowing for a certain degree of misalignment.  
         [0041]    [0041]FIG. 10 depicts an isometric sectional view of a compressed gas cylinder and mount assembly  400  according to a fourth embodiment of the present invention. Cylinder and frame assembly  400  makes use of a cylindrical bearing  410 . Cylindrical bearing  410  is disposed around the outer surface of neck  406 . The inner surface  422  of cylindrical bearing  410  is shaped and sized to mate with the outer surface of the neck  406 .  
         [0042]    In the embodiment shown in FIG. 10, the inner surface  422  is cylindrical, in order to conform to the cylindrical shape of the neck  406 . Cylindrical bearing  410  is slidable on neck  406 . As assembled, cylindrical bearing  410  seats against a cylindrical inner surface  416  in the frame  402 . Similarly, neck  422  has a certain degree of freedom of movement in axial displacement within cylindrical bearing  410 , with such axial displacement being bounded on the one end by the shoulder on  422  and at the other end by securement plug  420 . With this arrangement, the cylindrical bearing  410  is captured within frame  402  by securement plug  420 , but is otherwise free to slide axially within frame  402 . Similarly, neck  422  has a certain degree of freedom of movement in axial displacement within cylindrical bearing  410 , with such axial displacement being bounded on the one end by the shoulder on  422  and at the other end by securement plug  420 . Depending on the specific application, securement plug  420  may be secured to neck  406  by a variety of structures, including a threaded connection, a snap fit, a press fit or any other method known to those of skill in the art. In the embodiment shown in FIG. 10, securement plug  420  incorporates a fill port  424  for filling and evacuation of gas cylinder  404 .  
         [0043]    Those of skill in the art will appreciate that, although this design allows for a substantial degree of axial translation, it allows for only a very limited degree of axial misalignment. Where axial alignment is a concern, the incorporation of a spherical bearing may be advisable. In certain embodiments, assembly  400  may also incorporate one or more features similar to locating collar  220 , described above, to fix the rotational location of the cylinder  404  while still allowing for a certain degree of misalignment.  
         [0044]    Cylinder and frame assembly  500 , depicted in FIG. 11, makes use of a combination spherical/cylindrical bearing  510 . Spherical/cylindrical bearing  510  is disposed around the outer surface of neck  506 . The inner surface  522  of spherical/cylindrical bearing  510  is shaped and sized to mate with the outer surface of the neck  506 . In the embodiment shown in FIG. 11, the inner surface  522  is cylindrical, in order to conform to the cylindrical shape of the neck  506 .  
         [0045]    Spherical/cylindrical bearing  510  is slidable on neck  506 . As assembled, spherical/cylindrical bearing  510  seats against a spherical inner surface  516  in the frame  502 . With this arrangement, the spherical/cylindrical bearing  510  is captured within frame  502  by retainer  520 , but has a certain freedom of orientation within frame  502 . Similarly, neck  506  has a certain degree of freedom of movement in axial displacement within spherical/cylindrical bearing  510 , with such axial displacement being bounded on the one end by shoulder  526  and at the other end by retaining plate  528 .  
         [0046]    Depending on the specific application, retaining plate  528  may be secured to neck  506  by a variety of structures, including a threaded connection, a snap fit, a press fit or any other method known to those of skill in the art. In the embodiment shown in FIG. 11, retaining plate  528  is secured to neck  506  by a set of threaded fasteners  530 .  
         [0047]    Those of skill in the art will appreciate that, this design allows for a substantial degree of axial translation, as well as a substantial degree of axial misalignment. In certain embodiments, assembly  500  may also incorporate one or more features similar to locating collar  220 , described above, to fix the rotational location of the cylinder  504  while still allowing for a certain degree of misalignment.  
         [0048]    While this invention has been described in reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.