Abstract:
A system for controlling slurry flow through a flexible-walled transport tube. An example system includes a frame, a pivot pin, a rotatable radial arm having an attached pressure pad, a spring tension adjustment rod extending between the radial arm and the frame, and a coil spring concentric with the spring tension adjustment rod and configured to oppose rotation of the radial arm away from a flexible-walled transport tube contacting the pressure pad. In one operating condition, a decrease in the pressure of the slurry within the transport tube reduces the force applied by the slurry outward on the tube wall, leading the spring to rotate the radial arm toward the tube, causing the contact pad to deflect the wall of the flexible-walled transport tube and impeding the flow of slurry through the tube.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority from provisional U.S. Patent Application No. 61/186,750, filed Jun. 12, 2009, the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    In the delivery of concrete slurries though a pipe or tube, there is typically a requirement to control the flow. In cases where flow is driven by applied pressure at the source, for example by pumping, slurry may continue to flow out of the pipe or tube even after pressure is removed, due to gravity, inertia, or sustained pressure in the hose. In the case where pressure was removed in order to halt the flow, this creates the undesirable condition where slurry flow continues for a short time even after the flow is desired to be stopped. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention includes a system for controlling slurry flow through a transport tube. An example system includes a frame, a pivot pin, and at least a pair of opposing radial arms. The arms rotate about the pivot pins and each has a pressure pad attached at an end opposite the pivot pin. A spring tension adjustment rod extends between the radial arm and the frame. A coil spring is mounted on the adjustment rod for applying pressure to a flexible-walled transport tube that is in contact with the pressure pad. 
         [0004]    When pressure is applied to a slurry in the transport tube, pressure from the slurry is exerted outward on walls of the transport tube. The outwardly exerted pressure forces the arms into an open position, thus allowing the slurry to flow through the tube. When the pressure is removed from the slurry, the arms are forced by the springs to a closed position, thus stopping the flow of slurry through the tube. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Preferred and alternative examples of the present invention are described in detail below with reference to the following drawings: 
           [0006]      FIGS. 1 and 2  illustrate front plan views of an example system formed in accordance with an embodiment of the present invention;  FIG. 3  illustrates a side plan view of the example system shown in  FIGS. 1 and 2 ; and 
           [0007]      FIGS. 4A and 4B  illustrate top plan views of an example system formed in accordance with a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0008]      FIGS. 1-3  illustrate an embodiment of an example slurry flow control device  10  designed to control flow of an applied slurry (such as concrete) through a flexible-walled transport tube  12 . The slurry control device  10  includes a frame  14 , a first flow restrictor  18  and a second flow restrictor  22 . Each flow restrictor includes first and second swing arm components  26 ,  30 , respectively. 
         [0009]    In one embodiment, the frame  14  is an elongated box-like structure that includes top segments  14 - 1 , bottom segments  14 - 2  and four vertical segments  14 - 3 . The four vertical segments  14 - 3  connect the top segments  14 - 1  to the bottom segments  14 - 2 . The first flow restrictor  18  is located in an upper half of the frame  14  and the second flow restrictor  22  is located in a lower half of the frame  14 . The flexible-walled transport tube  12  passes through each of the first and second flow restrictors  18 ,  22 , and through the top and bottom frame segments  14 - 1 ,  14 - 2 . 
         [0010]    The swing arm component  26  includes a pressure pad  38 , a radial arm  42 , a radial arm bracket  44 , a pair of pivot pins  46 , and a tension application component  34 . The swing arm component  30  includes a pressure pad  60 , a radial arm  62 , a radial arm bracket  64 , a pair of pivot pins  66 , and a tension application component  70 . As shown in  FIG. 3 , the radial arms  42  and  62  are substantially rigid U-shaped structures, where each end of the arms rotates about a respective pair of pivot pins  46 ,  66 . The pair of pivot pins  46 ,  66  is affixed to the top frame segment  14 - 1  and both pins of a pair lie along a common longitudinal axis. The bottoms of the radial arms  42 ,  62  (opposite end from the pivot pins  46 ,  66 ) provide a mounting position for the respective pressure pads  38 ,  60 . The radial arm bracket  44  spans from one branch of the radial arm  42  to the other and provides a mounting point for the tension application component  34 . The radial arm bracket  64  spans from one branch of the radial arm  62  to the other and provides a mounting point for the corresponding tension application component  70 . 
         [0011]    The pressure pads  38 ,  60  are barrel-shaped structures, substantially rigid, that are attached to a base section of the respective arms  42 ,  52 . The pressure pads  38 ,  60  are oriented so that a portion of the rounded surface of the pressure pads  38 ,  60  face and come in contact with the flexible-walled transport tube  12 . 
         [0012]    As shown in  FIG. 1 , each of the tension application components  34 ,  70  includes a spring  48 ,  72 , a spring tension adjustment rod  50 ,  76 , and a spring tension adjustment nut  54 ,  74 . The spring tension adjustment rods  50 ,  76  are rigid, at least partially threaded rods fixed at one end to the radial arm brackets  44 ,  64  and adjustably secured at the other end to vertical adjustment rails  58 . The vertical adjustment rails  58  extend between the top and bottom segments  14 - 1 ,  14 - 2  of the frame  14 . As shown in  FIG. 3 , the spring tension adjustment rods  50 ,  76  are held in tension by the compression of the springs  48 ,  72 , which pull the spring tension adjustment nuts  54 ,  74  against the outside of the vertical adjustment rails  58 . 
         [0013]    Both the position and the resistance to movement of the radial arms  42 ,  62  are regulated by the springs  48 ,  72 . Longer springs position the radial arms  42 ,  62 , closer to one another, thus making the flow control device  10  more suitable for a narrower transport tube  12 . Shorter springs make the flow control device  10  more suitable for a wider transport tube  12 . A stiffer spring  48 ,  72  makes the radial arm  42 ,  62  more resistant to movement, thereby making the device  10  suitable for more viscous slurries. A softer spring  48 ,  72  makes the radial arm  42 ,  62  less resistant to movement, thereby making the device  10  suitable for less viscous slurries. The tension of a given spring  48 ,  72  can be adjusted by tightening or loosening the spring tension adjustment nut  54 ,  74 , making the spring  48 ,  72  softer or stiffer. 
         [0014]    The first and second swing arm components  26 ,  30  are positioned on opposing sides of an axis bisecting the frame  14  from top to bottom. The radial arms  42 ,  62  are positioned within the frame  14  to swing substantially parallel to one another in intersecting arcs. As shown in  FIG. 1 , in one embodiment the radial arms  42 ,  62  differ in length, leading the flexible-walled transport tube  12  to be bent over between the pressure pads  38 ,  60 . 
         [0015]    The slurry flow control device  10  operates to regulate slurry flow through the accompanying flexible-walled transport tube  12 . As shown in  FIG. 1 , the flexible-walled transport tube  12  passes through the top segment  14 - 1  and the bottom segment  14 - 2  of the frame  14 . As the flexible-walled transport tube  12  passes through the frame  14 , the tube  12  passes between the pressure pads  38 ,  60  of the first and second flow restrictors  18 ,  22 . The length of each spring  48 ,  72  is selected so that each pressure pad  38 ,  60  is positioned a distance apart from one another such that each pressure pad  38 ,  60  contacts the outside wall of the flexible-walled transport tube  12 . When pressure within the tube  12  is high (above a threshold), as under a pumping condition, the swing arm components  26 ,  30  retract under the force of the slurry pressure exerted outward on the wall of the tube  12 , allowing slurry to exit the tube  12 . When pressure within the tube  12  is low (below a threshold), as under a non-pumping condition, the swing arm components  26 ,  30  rotate back toward the tube  12 , closing off the interior of the tube  12  and preventing slurry from exiting the tube  12 . 
         [0016]    As shown in  FIG. 3 , the vertical adjustment rail  58  includes a pair of rigid vertical supports extending from the top segment  14 - 1  to the bottom segment  14 - 2 . The supports form a slot to accept the spring tension adjustment rod  50 . The extent to which the swing arm components  26 ,  30  can rotate back toward the tube  12  is limited by the spring tension adjustment nuts  54 ,  74 , which become pulled against the outside of the vertical adjustment rails  58 . The slot allows the spring tension adjustment rod  50 ,  76  to be moved up or down relative to the radial arm  42 ,  62 . This adjustment is useful for keeping the spring  48  approximately tangent with the arc traced by the radial arm  42 ,  62 . The spring tension adjustment nut  54  is threaded onto the adjustment rod  50 . Tightening of the spring tension adjustment nut  54 ,  74  draws the adjustment rod  50  through the slot, shortening the length of the adjustment rod  50 ,  76  between the radial arm  42 ,  62  and the vertical adjustment rail  58 . 
         [0017]    As illustrated in  FIGS. 1-3 , the example slurry flow control device  10  includes a first and second flow restrictor  18 ,  22 . In this embodiment, the second flow restrictor  22  is constructed and operates substantially the same as the first flow restrictor  18 . The two flow restrictors  18 ,  22  work cooperatively, in series along the transport tube  12 , to control the flow of slurry through the transport tube  12 . 
         [0018]      FIGS. 4A and 4B  show an alternative embodiment of the fluid flow control device  80 . The device  80  includes a frame  84 , a left-hand frame  84 - 1  and a right-hand frame  84 - 2 . The frames  84 - 1 ,  84 - 2  are essentially two halves of the frame  84  split in half between the swing arm components  26 ,  30 . The frames  84 - 1 ,  84 - 2  are mechanically connected to one another by at least one hinge  86  and at least one clasp device  90 . A loop feature  94  is attached to the left-hand frame  84 - 1 . A hook feature  98  is attached to the right-hand frame  84 - 2 . The clasp device  90  is adjustable in length. The clasp device  90  includes a loop on one end and a hook on the other end. When the device  80  is in closed position, the loop of the clasp device  90  is received by the hook feature  98  and the hook of the clasp device  90  is received by the loop feature  94 , thus clamping the two frames  84 - 1 ,  84 - 2  together.  FIG. 4B  shows the device  80  in an open position. In the open position the clasp device  90  is removed, thus allowing the two frames  84 - 1 ,  84 - 2  to rotate about the hinge  86 . When the device  80  is in the open position, the transport tube  12  is easily loaded into the fluid flow control device  80  without requiring a free end of the transport tube  12  to be fed through the frame. 
         [0019]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. For example, the device may include radial arms that are L-shaped or some other shape provided a pad can apply the proper pressure to the received tube. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.