Abstract:
A collapsible liquid storage tank for use in a freight container for selectively carrying solid freight and bulk liquid freight includes a substantially rigid gantry having a plurality of support posts, a first frame, a second frame suspended from the gantry, a substantially inelastic flexible fabric container having sidewalls connected between the first frame and the second frame, a water impermeable elastic bladder disposed within the fabric container, and a hoist coupled between the gantry and the second frame for lifting the second frame towards the first frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    None 
       REFERENCE TO A “SEQUENCE LISTING” 
       [0003]    None 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Technical Field 
         [0005]    This invention relates generally to collapsible tanks for freight containers that allow the freight container to be converted to selectively carry solid freight or bulk liquid freight, and more particularly to a collapsible tank that is both stronger and easier to clean than heretofore known tanks. 
         [0006]    2. Description of Related Art 
         [0007]    Collapsible tanks of the general type with which this invention is concerned are shown in U.S. Pat. No. 6,015,055; 6,065,265; 6,131,756; 6,216,900; and 6,299,437. 
       SUMMARY OF THE INVENTION 
       [0008]    While the collapsible containers described in the patents mentioned above have been very successful and have provided significant advantages over liquid transfer vessels used in the past, there is a need for such containers that are especially adapted for use in transporting liquid food products, and particularly for containers for storing and transporting food products which containers are inexpensive, light, and easy to clean. It is to these characteristics of containers for transporting liquids that the present invention is addressed. 
         [0009]    Heretofore, such tanks have employed a flexible inner liner and a flexible outer shell attached to top and bottom frame portions of the tank. 
         [0010]    A disadvantage of constructions of the type heretofore used is that it is desirable, for reducing the load on the outer shell and the structure supporting the tank, that the sides and perhaps the bottom of the tank be permitted to swell to a slightly rounded shape when filled with liquid, to reduce stresses on the tank material. For cleaning purposes, it is preferable that the sides and bottom of the tank be relatively flat so that they may be effectively cleaned between uses 
         [0011]    Briefly stated and in accordance with one aspect of this invention a collapsible liquid storage tank for use in a freight container for selectively carrying solid freight and bulk liquid freight includes a substantially rigid gantry having a plurality of support posts, a first frame, a second frame suspended from the gantry, a substantially inelastic flexible fabric container having sidewalls connected between the first frame and the second frame, a water impermeable elastic bladder disposed within the fabric container, and a hoist coupled between the gantry and the second frame for lifting the second frame towards the first frame. 
         [0012]    In accordance with another aspect of the invention the collapsible liquid storage tank includes an impermeable elastic bladder that is smaller than a substantially inelastic flexible fabric container when the water impermeable elastic bladder is relaxed and larger than the substantially elastic fabric container when the water impermeable elastic bladder is expanded so that the expanded size of the bladder is limited by the substantially in the last flexible fabric container. 
         [0013]    In accordance with another aspect of the invention the water impermeable elastic bladder has a substantially smooth inner surface when not expanded to facilitate cleaning. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0014]      FIG. 1  is a rear elevation of a collapsible storage tank in accordance with this invention shown positioned within the body of a trailer. 
           [0015]      FIG. 2  is a top rear perspective view of the upper portion of the gantry and upper frame of a collapsible storage tank in accordance with this invention. 
           [0016]      FIG. 3  is an enlarged perspective view of a cleaning portal of a collapsible storage tank in accordance with this invention. 
           [0017]      FIG. 4  is a rear elevation of an empty tank in accordance with this invention. 
           [0018]      FIG. 5  is a rear elevation of a collapsible storage tank shown filled with liquid in accordance with this invention. 
           [0019]      FIG. 6  is a detailed view of the upper attachment portion of the tank in accordance with this invention. 
           [0020]      FIGS. 7A and 7B  are side elevations partly in section of the collapsible storage tank of this invention, shown empty and full, respectively. 
           [0021]      FIG. 8  is an exploded fragmentary view showing the manner in which the fabric container and inner bladder are attached to the frame of the invention showing the substantially inelastic flexible fabric container and the elastic bladder in section. 
           [0022]      FIG. 9A  is a side elevation showing the lifting mechanism for the collapsible storage tank of this invention. 
           [0023]      FIG. 9B  is a side elevation showing the collapsible storage tank of this invention in transition from its deployed configuration to a stowed configuration. 
           [0024]      FIG. 10  is a rear elevation showing the collapsible storage tank of this invention in transition between the deployed position and the collapsed position. 
           [0025]      FIG. 11  is a rear elevation showing the collapsible storage tank of this invention shown in the fully collapsed storage configuration. 
           [0026]      FIG. 12  is a rear view, in perspective, showing the storage tank in the stowed position with cargo positioned beneath the tank. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]      FIG. 1  is a rear elevation of a collapsible liquid tank  10  in accordance with this invention shown positioned within the body of a trailer used to transport the tank and other cargo. The tank  10  is attached between and supported by upper  12  and lower  14  frame members that are suspended from a gantry  16  that includes a plurality of short vertical supports  17  along each side and an upper gantry platform comprising a plurality of cross beams  18  attached to the upper frame  12 . The lower frame  14  is connected to the upper portion of the gantry by cables  34  (see  FIG. 2 ) that permit the frame members to be selectively lowered into a liquid receiving configuration as shown in  FIG. 1  or raised to the upper portion of the gantry for storage as shown in  FIGS. 10-12 . As can also be seen more clearly in  FIGS. 2 ,  9 A and B,  11  and  12 , the gantry includes intermediate left and right horizontally arranged support rails  19 ,  21 , on which the ends of the plurality of transverse support beams  1   8  rest when the tank is in the deployed configuration. The liquid storage tank has an outlet port  20  that may be connected to a hose  22  for emptying the tank while it remains situated within the trailer. Optionally, a plurality of straps (not shown) can be attached between fittings on the floor of the trailer and the upper frame of the tank to retain the tank in position during transport. 
         [0028]      FIG. 2  shows the upper portion of the gantry  16  and the upper platform in more detail. The upper frame  12  includes a rectangular outer portion to which the tank material  26  is attached as shown in more detail below and a plurality of transverse members  18  forming the platform  18  secured to the rectangular frame  12 . The transverse members  18  are spaced closely enough to permit support plates  30  to be attached thereto for permitting service persons to walk along the upper surface of the platform to access the cleaning portal  32  opening into the tank and of sufficient size to receive a cleaning person, or automatic or manual cleaning apparatus. As can be seen in  FIG. 2  and also in  FIGS. 9A and 9B , the ends of the transverse members  18  rest on the upper surface of the horizontal supports  19  and  21 . The upper frame  12  is attached to the transverse members and is supported thereby when the tank is in the deployed position as shown in  FIG. 2 . The lower frame member  14  is supported by the tank material, and preferably rests on or near the floor of the trailer as shown in  FIG. 1 . 
         [0029]    The gantry includes a plurality of short vertical support members  17 , a long double support member  37 ,  43  at each corner, and a single support member  15  along each side disposed between the double support members. The double support members  37  support the pulleys  42  around which the lifting cables  34 ,  36  are entrained. The single support members support the horizontal support rails  19  and  21 , and also act as guides for the transverse members  18 , which, as can be seen in  FIGS. 2 and 9 , engage the vertical support members  37 ,  43 ,  15  on different sides to prevent the upper frame member  12  from swinging to and fro. 
         [0030]    Cables  34 ,  36  are attached to a motorized winch  40  and entrained over pulleys  42  mounted to the upper platform of the gantry and then downwards to the lower support frame  14  for the tank. 
         [0031]      FIG. 3  is an enlarged view of the cleaning portal  32  showing a cover  56  mounted to a pivot arm  58  swung out of position to permit a cleaning hose to be inserted into the portal  32 . A latch  60  or a plurality of latches positioned around the periphery of the cleaning portal secure the cover in a closed position for transport. Preferably, the portal  32  is sufficiently large to allow a person to enter, or to allow a cleaning apparatus to be inserted into the tank. 
         [0032]      FIG. 4  shows the tank of this invention in an empty state in which the outer container is not expanded. Note that although the outer container is not expanded, the liquid impermeable elastic bladder  64 , not visible in this view, but visible in  FIG. 7A , is relatively smooth on the inside surface, thus facilitating cleaning of the tank. 
         [0033]      FIG. 5  is a side elevation similar to  FIG. 1  showing the tank in the full condition. The tank  10  includes a substantially inelastic flexible fabric outer container  26  and a liquid impermeable elastic bladder  64  not visible in  FIG. 4  or  FIG. 5 . By providing an outer container  26  that is shaped to allow a slight bulging when filled, the stresses on the outer container are substantially reduced from the stresses that would be present in a rigid container or a container not allowing a slight bulge. 
         [0034]      FIG. 6  shows a corner of the upper frame  12  illustrating the manner in which the inner and outer tank materials  64 ,  26  are connected to the frame. The fabric container  26  and the elastic bladder  64  obscure the upper frame  12  in  FIG. 6 . The fabric container  26  is preferably provided with a folded over sealed edge  70  forming a compartment through which a rope  72  in the nature of a drawstring or cord or the like is passed to make the upper edge of the fabric container slightly thicker than the fabric itself to prevent it from slipping. The container  26  and the inner bladder  64  are secured to the upper frame  12  by elongated U-shaped battens  74  preferably metal, or a similar structure through which bolts  76  or other fasteners are passed as more clearly shown in the detailed view of  FIG. 8 . 
         [0035]      FIGS. 7A and 7B  are partially exploded partially sectioned end views of a collapsible liquid storage tank  10  in accordance with this invention.  FIG. 7A  shows battens  74  attached to the upper tank support frame  12  and the lower frame  14 , and a sectioned view of the inelastic flexible fabric container  26  and the liquid impermeable elastic bladder  64 . 
         [0036]    As can be seen from  FIG. 7A , the substantially inelastic flexible fabric container  26 , which is preferably made from Kevlar or a similar inelastic material, has a longer peripheral section than the unexpanded water impermeable elastic bladder  64 . In this way, the elastic bladder  64  can be readily cleaned when the tank is empty as shown in  FIG. 7B . Preferably, but not necessarily, the elastic bladder  64  is at least slightly stretched when the tank is empty so that it presents a smooth surface for cleaning. When the tank is filled, the elastic bladder  64  (but not the substantially inelastic flexible fabric container  26 ) stretches. The extent of stretching of the elastic bladder  64  is limited by the inelastic flexible fabric container  26 . It is not necessary to provide reinforcing materials in the elastic bladder. The inelastic fabric container limits the amount of expansion. This allows a relatively less expensive unreinforced bladder to be employed than has been possible heretofore. Allowing the bladder to stretch to the bowed shape of the inelastic fabric container shown in  FIG. 13  reduces the stresses on the fabric container and the bladder, thereby allowing the support frame to be made lighter so as to increase the useful load that can be carried by the tank. 
         [0037]    Preferably, the inelastic fabric container  26  and the elastic bladder  64  are secured to the upper and lower frames by a securing rail or batten  74  attached to the frame by a bolt or similar fastener as shown in  FIG. 8 . The upper attachment is shown exploded for clarity. 
         [0038]      FIG. 8  is an exploded view of the upper attachment portion showing the portion of the frame, the U-shaped attachment plate or batten, the bolt  76  and nut  78  in more detail. The inelastic flexible fabric container upper edge portion is preferably provided with an enlarged bead  70  to prevent the fabric layer from slipping out of the clamp. The elastic bladder  64  is preferably provided with a similar bead  86 . As shown in  FIG. 8 , the bolt extends through the batten  74 , the fabric container  26 , the bladder  64 , and the upper frame. As can be seen, both the fabric container and the elastic bladder are held in position by the pressure between the frame element and the batten, as well as by the enlarged edges  70 ,  86  that prevent the fabric and the bladder from slipping through the space between the frame and the batten. The elastic bladder  64  also preferably has a top portion welded to the side portion to provide substantially complete containment of the fluid contents. 
         [0039]    As shown in  FIGS. 9-11 , the cables  34 ,  36  extend from winch  40  around the pulleys  42  attached to top caps  35  bridging the dual gantry end supports  43  to attachment points  44  on the lower frame  14 . When the cables  34 ,  36  are retracted to put the tank in the storage position, the lower frame  14  is raised from a position on the floor of the trailer to a position adjacent the top of the gantry  16 . The upper frame  12  and transverse members  18 , which are preferably not attached to the cables, are raised with the lower frame  14  when the lower frame is lifted. 
         [0040]    The ends of transverse members  18  engage the vertical support portions  37 ,  43 ,  15  of the gantry  16  to keep the upper frame  12  at least loosely aligned with the gantry. Left and right horizontal support rails  19 ,  21  support the transverse cross members  18  from which the upper frame  12  is suspended at a position intermediate the top of the gantry  16  and the bottom of the trailer. The rails are attached to the approximate midpoint of the vertical support members of the gantry  16  or alternatively, cables may be attached to the upper frame  12  that permit the upper frame  12  to be lowered into a position only part-way down the gantry structure. 
         [0041]      FIGS. 9A and 9B  are side elevations of the storage tank of this invention shown in its lowered position, but not filled with liquid. The gantry, vertical supports, and lifting arrangement can be seen in this figure. The cables are entrained around pulleys and attached to an upper portion of the lower frame member  14  for raising the frame member to move the tank from the deployed condition to the stowed condition as shown and described below in connection with  FIGS. 10 and 11 . 
         [0042]      FIG. 9A  shows the liquid storage tank of this invention and a deployed configuration. The cables  34  extending over pulleys  42  from winch  40  are fully extended so that the lower frame member  14  essentially rests on the floor of the trailer or at least proximate thereto. The upper frame member  12  is supported by cross members  18 , the ends of which rest on side rails  19  and  21 . The walkway  30  is supported on the upper surfaces of the cross members  18 . The gantry structure can be easily visualized from this view. The dual vertical supports  37  and  43  extend from the floor of the trailer to top caps  35 . Supports  37  and  43 , as well as the supports on the other side of the structure, not visible in  FIGS. 9A and 9B , are preferably strong enough to support the full weight of the empty tank when it is raised from the deployed configuration to the stored configuration. Aluminum or steel tubes, round or other configuration, may be used. 
         [0043]    A plurality of shorter vertical supports  17  extend from a bottom rail  90  mounted or resting on the floor of the trailer to intermediate horizontal support rails  19  and  21 . Note that the intermediate rails  19  and  21  may be formed in one or more pieces that are attached to the tops of the vertical supports and/or interrupted and welded thereto. 
         [0044]    As can be seen from  FIGS. 9A and 9B , the transverse members  18  are spaced such that different members are disposed on different sides of the vertical gantry members  37 ,  15 ,  43 . This arrangement substantially prevents the tank frame from swinging longitudinally, that is in the left-right direction as seen in  FIGS. 9A and 9B , as the tank is raised and lowered. Side to side movement, as shown for example in  FIGS. 4 and 5 , is largely restricted by the side frames. 
         [0045]    As can be seen in  FIG. 9B , when the tank is lifted, the cables raise bottom frame member  14 , and at the same time collapse the tank  10  from the bottom up until the top frame member  12 , cross members  18 , and walkway  30  are all lifted as a unit to the top of the gantry. 
         [0046]    This lifting can also be seen in  FIGS. 10 and 11  where the cables cannot be seen. 
         [0047]    FIGS.  10  and  1 I 1  show a storage tank  10  in accordance with this invention being raised from a configuration in which liquids are stored in the tank (see  FIG. 9A ) to a stored configuration in which cargo can be placed in the trailer beneath the collapsed tank. The tank in the liquid receiving configuration is shown in  FIGS. 4 ,  5 , and  9 , for example.  FIG. 10  shows an intermediate position in which the lower frame  14  has been raised by cables  34 ,  36  to a position where the liquid containing portion has been collapsed and the bottom frame  14  engages the upper gantry platform beams  18  from below. As the lower frame  14  continues to be lifted upward by the cables, it carries the upper frame  12  and upper platform beams  18  with it until it reaches the storage position shown in  FIG. 11 . 
         [0048]      FIG. 12  shows the tank structure raised into a storage position with the dry cargo  80  loaded onto the trailer beneath the collapsed tank. As can be seen, the upper  12  and lower tank  14  frames are drawn into position closely adjacent to each other and adjacent the upper platform beams  18  of the support gantry.