Abstract:
A lifting assembly for a polymeric liner disposed within a fluid material container. The assembly includes a pneumatic linear drive, and, an interface member that is supportively connecting to the polymeric liner. A tension line is coupled between the pneumatic linear drive and the interface member, and a line guide is positioned to route the tension line to a central location above the polymeric liner, and thereby correspondingly locates the interface member. A pneumatic controller actuates the pneumatic linear drive to move in a first direction, to move in a second direction, or to remain in a fixed position. Movement of the pneumatic linear drive in the first direction causes the tension line to lift the interface member in an upward direction, and, movement of the pneumatic linear drive in the second direction causes the tension line to lower the interface member in a downward direction.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to fluid material containers that are lined with a polymeric bag-type liner. More particularly, the present invention relates to an assembly for raising and lowering such a liner as it is filled or emptied, by using a pneumatic linear drive. 
         [0003]    2. Description of the Related Art 
         [0004]    Storage and processing containers are in widespread use in various industries and other endeavors. Many of these are used to contain liquids and other flowable bulk materials, such as powders and granular materials. While containing certain types of fluid materials, it is preferable to line the container with a polymeric membrane so that the bulk material is either impermeably contained in a suitable polymeric material, or to insure that the bulk materials does not contact the container itself. For example, in the case of pharmaceutical and food grade materials, a polymeric liner, such as PVC or polypropylene, may be used to maintain the purity and cleanliness of the bulk material. In other instances, the bulk material may react with a storage container itself, so a polymeric liner is used to prevent such reactions. 
         [0005]    Various fluid material containers can be employed, and one useful configuration is a rectangular stainless steel bin that has an open top. The liner is inserted from the top, and then plumbing connections are made to the bin and liner combination, as is known in the art. In other applications, the liner is inserted through a door of the host container. As the liquid, or fluid, is filled into the liner, it is necessary to control the position and movement of the liner to insure that it fits properly into the volume of the bin, and that the liner does not become improperly oriented or creased. If this occurs, then the liner may be damaged, or the maximum volumetric capacity of the bin and liner combination may not be realized. One approach to dealing with these potential problems has been to access the liner from the open top of the bin, and raise and lower it as the fluid material is added and removed from the bin. That way, improper fit can be adjusted before the liner becomes filled with the fluid material. Thus it can be appreciated that there is a need in the art for a system for mitigating the potential risk of filling and emptying bin liners in a manner that raises and lowers the liner during installation, filling, emptying and removal from a bin or other bulk material container. 
       SUMMARY OF THE INVENTION 
       [0006]    The need in the art is addressed by the teaching of the present invention. The present disclosure teaches a lifting assembly for a polymeric liner that disposed within a fluid material container. The assembly includes a pneumatic linear drive, and an interface member that is adapted for supportively connecting to the polymeric liner. A tension line is coupled between the pneumatic linear drive and the interface member, and a line guide is positioned to route the tension line to a central location above the polymeric liner, which thereby correspondingly locates the interface member. A pneumatic controller actuates the pneumatic linear drive to move in a first direction, to move in a second direction, or to remain in a fixed position. Movement of the pneumatic linear drive in the first direction causes the tension line to lift the interface member in an upward direction, and, movement of the pneumatic linear drive in the second direction causes the tension line to lower the interface member in a downward direction. 
         [0007]    In a specific embodiment of the foregoing assembly, where the polymeric liner is a bag structure that includes support fitments, the interface member includes at least a first connector adapted to engage the support fitments. In a refinement to this embodiment, where the support fitments are selected from a loop of polymeric material, an eyelet inserted through the polymeric material, and a reinforced portion, the first connector is selected from a hook, a ring, a karabiner, and a clamp. 
         [0008]    In a specific embodiment of the foregoing assembly, where the fluid material container is a rigid structure with an open top, the interface member is inserted through the open top. In another specific embodiment, the pneumatic linear drive is a rodless pneumatic cylinder. 
         [0009]    In a specific embodiment of the foregoing assembly, the interface member is a spider structure with a central joint that is connected to the line guide with spider arms extending outwardly, which are connected to the polymeric liner. In another specific embodiment, the tension line is a cable. In another specific embodiment, the line guide includes a pulley, around which the tension line is routed. 
         [0010]    In a specific embodiment, the foregoing assembly further includes a housing that contains the pneumatic linear drive, and which is configured for mounting to the fluid material container. In a refinement to this embodiment, the housing includes a line guide support member, which orients the line guide at the central location above the polymeric liner. In a further refinement, the line guide support member extends as a cantilever from the housing to the central location. 
         [0011]    In a specific embodiment of the foregoing assembly, the pneumatic controller is a three-position, four-port, pneumatic valve with a closed center position. In another specific embodiment, the pneumatic controller is coupled within a pneumatic circuit that has a regulated pressure, and the pneumatic circuit further include a relief valve set to a pressure less than twenty percent greater than the regulated pressure, thereby limiting the maximum force exerted by the pneumatic linear drive. In a refinement to this embodiment, the assembly further includes a flow control orifice coupled to an exhaust port of the pneumatic controller, thereby controlling the rate of movement of the pneumatic linear drive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view drawing of a bag-lined fluid material container according to an illustrative embodiment of the present invention 
           [0013]      FIG. 2  is a top view drawing of a bag-lined fluid material container according to an illustrative embodiment of the present invention. 
           [0014]      FIG. 3  is a side view drawing of a pneumatic bag lift assembly according to an illustrative embodiment of the present invention. 
           [0015]      FIG. 4  is a side view drawing of a pneumatic bag lift assembly according to an illustrative embodiment of the present invention. 
           [0016]      FIG. 5  is a functional diagram of a pneumatic bag lift assembly according to an illustrative embodiment of the present invention. 
           [0017]      FIG. 6  is a pneumatic schematic of a bag lift assembly according to an illustrative embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0018]    Illustrative embodiments and exemplary applications will now be described with reference to the accompanying drawings to disclose the advantageous teachings of the present invention. 
         [0019]    While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope hereof and additional fields in which the present invention would be of significant utility. 
         [0020]    In considering the detailed embodiments of the present invention, it will be observed that the present invention resides primarily in combinations of steps to accomplish various methods or components to form various apparatus and systems. Accordingly, the apparatus and system components and method steps have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the disclosures contained herein. 
         [0021]    In this disclosure, relational terms such as first and second, top and bottom, upper and lower, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
         [0022]    An illustrative embodiment of the present invention is applied to the pharmaceutical industry, and in particular, processing bins that employ polymeric liners to impermeably retain a fluid content, which is commonly a liquid. Such processing and storage bins are commonly fabricated from stainless steel, for the benefits of corrosion resistance, sanitation, and durability. The polymeric liners are generally flexible bag-like structures that can be replaced from time to time. Such replacement may occur through an open top of the container, or through door openings located through the container walls. For this and other reasons, the exterior walls of such containers may have doors installed for access to the interior. Such doors contain the polymeric liner in the same fashion as the walls. The liners are fabricated to the same dimensions and shape as the interior of the host container, which is commonly rectangular. As such, it is important to position and orient the liner in a manner that will allow the form-fitted liner to fill and fit the interior shape of the container. Lifting the top of the liner, so as to ‘stretch’ it out and enable the liner membrane to fit neatly into the container as it is filled, can facilitate this. A similar issue may present itself as the liner is emptied of fluid, as well as while the liner fluid volume fluctuates during production and operations. 
         [0023]    In general, the assembly of this disclosure comprises is a device to lift the top of a bag, or liner, inside a bin or bag holder, that holds the bag up while filling the bag with product and while discharging the product. The illustrative embodiment assembly consists of a pneumatic rodless cylinder contained within a vertical housing, so as to be completely concealed, with a cable that is routed up to the top of the vertical tube, through a horizontal tube, exiting in a vertical direction, and connected to a lifting frame, referred to as a ‘spider’, which reaches out to the four corners of the bag. A pneumatic hand valve controls flow of air to the pneumatic cylinder. When the carriage of the rodless cylinder travels up the spider travels down, and when the carriage of the rodless cylinder travels down, the spider travels up. Additionally, the pneumatic line coupled to drive the pneumatic cylinder that raises the spider includes a pressure relief valve, which is set to provide only slightly more pressure than is needed to lift and hold the bag up. If more pulling force is exerted on the bag lift, the pressure relief valve relieves, allowing the spider to lower, preventing too much force from being exerted on either the bag or the bag lift structure itself. 
         [0024]    Reference is directed to  FIG. 1 , which is a perspective view drawing of a bag-lined fluid material container according to an illustrative embodiment of the present invention. The bulk material container  2  is fabricated from stainless steel, and employs and exterior frame  4  made from structural shapes. Stainless steel sheet or plate  3  is applied to the frame and yields a generally smooth interior surface. The container has an open top  5 , and an access door  6  located on one of its exterior walls. Other process related fixtures are illustrated, but are not germane to the present disclosure. A stainless steel housing  8  is fixed to a corner of the container  2  using plural mounting clips  11  to removably engage the housing  8  to the container  2 . The housing  8  is elongated and oriented in a generally vertical orientation. Other orientations can be employed, including orientations where the housing  8  is not directly connected to the container  2 . A pneumatic linear drive (not shown) is disposed within the housing  8 , and includes certain pneumatic circuit components (not shown). Access to the interior of the housing  8  is provided by plural covered access openings  9 . In addition, a control housing  10  is fabricated as a portion of the housing  8  for containing control valves (not shown) and other pneumatic components (not shown). 
         [0025]    The housing  8  in  FIG. 1  serves as a mounting location for a line guide support member  12 , which has the form of a cantilevered structural arm in the illustrative embodiment. A tension line  13  is supported by the line guide support member  12  using one or more line guides (not shown), and with tension line routing also managed using the line guides (not shown). In the illustrative embodiment, the tension line  13  is a stainless steel cable, the line guides are pulleys, and the line guide support member  12  is a structural tube. The tension line  13  is positioned near the central area of the open top  5 , and is oriented in a vertical direction. The tension line  13  is coupled to a spider structure  14 , which as four arms that extend toward the four corners of the open top  5  of the container  2 . In the illustrative embodiment, the spider structure  14  is fabricated from stainless steel tubing with reinforcing gussets to strengthen connections. The end of each spider structure  14  arm is terminated with a connector  16 . The connectors  16  attached to support fitments (not shown), which are a component of the bag liner (shown in phantom)  18  in  FIG. 1 . 
         [0026]    Reference is directed to  FIG. 2 , which is a top view drawing of a bag-lined fluid material container  2  according to an illustrative embodiment of the present invention. The structural frame  4  of the container  2  is presented, with the stainless sidewalls  3  visible as well. The housing  8  of the bag lift assembly is connected to the exterior of the container  2 , and a cantilevered line guide support member  12  extends to the central areas of the open top of the container  2 . A control housing  10  extends from the side the housing  8 . The spider structure  14  extends to the four corners of the container  2 . There are connectors  16  at the end of each spider arm  14 , and in this embodiment the connectors  16  are rings, which engage support fitments (not shown) of the bag liner (also not shown). The spider assembly  14  travels up and down inside the container  2 , and serves to lift and extend the bag liner (not shown). The weight of the spider  14  and bag liner (not shown) are carried by the cantilevered line guide support member  12 , which is supported, in turn, by the housing  8 . 
         [0027]    Reference is directed to  FIG. 3  and  FIG. 4 , which are a side view drawing of a pneumatic bag lift assembly according to an illustrative embodiment of the present invention.  FIG. 3  illustrates the spider assembly  14  in the lowest position and  FIG. 4  illustrates the spider assembly  14  in the highest position. Both figures illustrate the entire bag lift assembly without showing the host bulk fluid material container or the bag liner. An elongated stainless steel housing  8 , which has a rectangular cross section, contains a pneumatic linear drive (not shown), and includes a control housing  10  for containing certain pneumatic controls, including an operator  19  for a pneumatic valve contained therein. The housing includes plural access openings  9  with removable covers for enabling access to internal components. A cantilevered line guide support member  12  extends laterally from the top of the housing  8 . In the illustrative embodiment, the line guide support member  12  is a rectangular stainless steel tube. The line guide support member  12  includes a pulley  20  at its distal end, which serves to route the tension line  13  to a vertical orientation. The tension member  13  in the illustrative embodiment is a stainless steel cable, although other manner of chain, cordage, and wire could be employed with suitable effectiveness. The tension line  13  is connected to a central point of bag interface member, or spider frame,  14 . The spider frame  14  is fabricated from stainless steel tubing with reinforcing gussets in the illustrative embodiment. The distal ends of the spider frame  14  arms have connectors  16  for connection to the bag liner (not shown). The connectors may be rings, hooks, clamps or karabiners, whichever is most suitable for particular support fitments present on the specific bad liner being supported. The bag liner support fitments may be a loop of polymeric material, a reinforced portion of polymeric material, eyelets, or other support fitments as are known to those skilled in the art. The key feature of the connectors  16  is that they are adapted to supportively engage these support fitments. 
         [0028]    Reference is directed to  FIG. 5 , which is a functional diagram of a pneumatic bag lift assembly according to an illustrative embodiment of the present invention. The bulk material container  2  is lined with a polymeric bag liner  18 , which is partially filled with a liquid  46  in this illustration. The bag interface member  14  supports the upper portion of the bag liner  18  using plural connectors  16 , which are connected to support fitments  24  that are included with the bag liner  18 . In this embodiment, the connectors  16  are stainless steel rings and the support fitments  24  are reinforced tabs having grommets inserted there through. The interface member  14  is a spider frame that is connected to a tension line  13 , which is a stainless steel cable in this embodiment. The tension line is routed over two pulleys  20 ,  22 . Pulley  20  is supported at the distal end of the line guide support member  13 , and pulley  22  is supported at the upper end of housing  8 . These pulleys  20 ,  22  serve to route the tension line  13  between vertical and horizontal orientation, as illustrated. The tension line  13  is terminated at a moving carriage  26  on a pneumatic linear drive  24 , which is a rodless pneumatic cylinder in the illustrative embodiment. In the illustrative embodiment, the rodless pneumatic cylinder is a Festo Corporation Series DGL linear drive having a 25 mm bore, and a length selected to match the corresponding container  2  height and bag  18  size. Festo Corporation has a US headquarters in Hauppauge, N.Y. and a web presence at www.festo.com. The pneumatic linear drive  24  is mounted within housing  8 , which is mounted to the bulk container  2  using plural mounting brackets  11 . 
         [0029]    The pneumatic linear drive  24  in  FIG. 5  is fixed within the housing  8 , and includes pneumatic line connections at interface ports  44 . A first pneumatic line  40  drives the carriage  26  up, and a second pneumatic line  42  drives the carriage  26  down. The pulleys  22 ,  20  route the tension line  13  to cause the spider  14  to move in the opposite direction of the carriage  26 . A control housing  10  is added as an appendage to the housing  8 , and provides a space for certain pneumatic elements. Among these is a 3-position, 4-port, center-closed, control valve  34 , which presents an operator handle  19  on the exterior of control housing  10 . Also included is a pressure relief valve  32  and a flow control orifice  36 . In addition, a pressure regulator  30  receives line pressure  28  from an external source, and delivers regulated air pressure to the control valve  34  through pneumatic line  38 . Further details of the pneumatic circuit will be discussed herein after. 
         [0030]    Reference is directed to  FIG. 6 , which is a pneumatic schematic of a bag lift assembly according to an illustrative embodiment of the present invention. An air supply line  28  delivers compressed air, typically in the 80-100 psi pressure range, which is regulated to approximately 50 psi by pressure regulator  30 . The regulated air is coupled via supply line  30  to an input port of control valve  34 , which is a 3-position, 4-port, valve  34 , and which has a closed center position. The control valve  34  is selectively operated by actuator  19 . The control valve  34  drives both input ports of the pneumatic linear actuator through air lines  40  and  42 . This is a conventional pneumatic cylinder drive arrangement, as is know to those skilled in the art. The line  40 , which drives the aforementioned interface member upwardly, is coupled to a pressure relief valve  32 , which is set to a nominal 55 psi. Note that this pressure is slightly higher than the supply line  38  pressure of 50 psi. This arrangement limits the force that can be imparted to the lifting operation of the assembly, and serves to prevent damage to the aforementioned line guide, tension line, interface member, and the bag liner itself. The range of up to twenty percent over pressure is suitable. The line  42 , which is used to lower the assembly generally does not require over-pressure protection. The exhaust line  39  out of the control valve  34  is routed through a flow limited orifice  36 . This serves to limit the rate at which the assembly moves during exhaust limited movement. 
         [0031]    Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications and embodiments within the scope thereof. 
         [0032]    It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention.