Abstract:
An apparatus for sealing a vacuum tank door. The apparatus comprises a circular flange attached to a door panel of a vacuum tank, a horizontal crossbar connected to the center of the door panel and a lifting assembly. The lifting assembly comprises an upper linkage arm, a lower linkage arm, and a hydraulic cylinder. Activation of the hydraulic cylinder causes the linkage assembly to move downwards pulling on the horizontal crossbar and pulling the vacuum tank door towards the tank. Activation of the hydraulic cylinder also causes a connection point of the lower linkage arm and the upper linkage arm to move over-center of the connection between the lower linkage arm to the to the tank creating a tight seal between the vacuum tank door and the tank.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of provisional patent application Ser. No. 61/481,600 filed on May 2, 2011, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the field of vacuum tanks, and in particular to a method or apparatus for sealing a vacuum tank in a vacuum system. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a sealing mechanism for sealing a vacuum tank. The vacuum tank comprises a door panel having a center point and a tank. The sealing mechanism comprises a circular flange attached to the door panel, a horizontal crossbar connected to and disposed proximate the center point of the door panel, and a lifting assembly attached to the horizontal crossbar. The lifting assembly comprises an upper linkage arm connected to the horizontal crossbar, a lower linkage arm connected to the tank, and a hydraulic cylinder connected to an end of the lower linkage arm. Activation of the hydraulic cylinder causes a connection point of the lower linkage arm and the upper linkage arm to move over-center of the connection between the lower linkage arm to the tank. 
     In another embodiment of the invention, the sealing mechanism for sealing a vacuum tank door comprises a circular flange attached to a door panel, wherein the circular flange comprises a lip, a horizontal crossbar connected to the lip of the circular flange, and a lifting assembly attached to the horizontal crossbar. The lifting assembly comprises an upper linkage arm connected to the horizontal crossbar, a lower linkage arm connected to the tank, and a hydraulic cylinder connected to an end of the lower linkage arm. Activation of the hydraulic cylinder causes a connection point of the lower linkage arm and the upper linkage arm to move over-center of the connection between the lower linkage arm to the tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the vacuum tank and the closed vacuum tank door. A tank door sealing mechanism is shown attached to the tank door along with a door lifting assembly attached on one side of the tank (an identical attachment exists on the opposite side) to open and close the door. 
         FIG. 2  is a side view of the vacuum tank and tank door of  FIG. 1 . The tank door is shown completely open. The door lifting assembly is shown completely extended and functioning to hold the door in an open position. 
         FIG. 3  is a front view of vacuum tank and door of  FIG. 1 . The door sealing mechanism is shown attached to the tank door. A sediment collector tank is also shown attached to the side of the vacuum tank. 
         FIG. 4  is a side view of the vacuum tank with the tank door closed. The vacuum tank is shown resting on a mounting bracket and the door lifting assembly is shown in its compacted position to cause the door to close the tank. 
         FIG. 5  is a side view of the opposite side of the vacuum tank shown in  FIG. 4 . The vacuum tank is shown resting on a mounting bracket and the door lifting assembly is shown in its compacted position holding the door against the tank. A hydraulic lifting assembly is also shown attached to the mounting bracket. 
         FIG. 6  is a perspective view of the vacuum tank and the closed vacuum tank door with an alternative embodiment of the door sealing mechanism shown in  FIG. 1 . 
         FIG. 7  is a front view of the embodiment of the vacuum tank door shown in  FIG. 6 . 
         FIG. 8  is a front view of an alternative embodiment of the vacuum tank door shown in  FIG. 1 . 
         FIG. 9  is a perspective view of the vacuum tank and the sealed closed vacuum tank door of  FIG. 8 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the figures and first to  FIG. 1 , a vacuum tank  1  is shown that is typically used in combination with other apparatuses to form a vacuum system.  FIG. 1  shows the vacuum tank  1  and the systems and methods for sealing the tank door  2  to the tank. The vacuum tank  1  is generally cylindrical, having a first end  38  and a second end  39 . The first end  38  of the vacuum tank  1  is generally open-ended and comprises a sealing flange  24  adapted to mate with the tank door  2  when the tank door is engaged with the vacuum tank  1 . The second end  39  of the vacuum tank  1  is generally closed at all times. It will, however, be appreciated that the second end  39  of the vacuum tank  1  may support a second tank door (not shown) thus allowing for easy access to the inside of the second end  39  of the vacuum tank  1 . 
     Referring still to  FIG. 1 , the vacuum tank  1  is shown resting on a mounting bracket  10  which is used in part to keep the tank  1  stable. The vacuum tank  1  may sit on the mounting bracket  10  on a trailer (not shown) in order to transport the vacuum tank  1  to various locations. The mounting bracket  10  is adapted to pivotally connect the tank  1  to a trailer (not shown) so that the tank  1  may be pivoted upward to allow for dumping of the contents contained therein. A hydraulic lifting assembly  50  ( FIG. 5 ) may be disposed under the vacuum, tank  1  and adapted to tilt the second end  39  of the vacuum tank  1  upward to facilitate dumping of the contents. 
       FIG. 1  shows the vacuum tank door  2  in a closed and sealed position. A sealing mechanism  23 , used to seal the door shut, is shown on the face of the tank door  2 . The sealing mechanism  23  works to evenly distribute the force placed on the door  2  when the door is in the closed position. Even distribution of the force upon the door ensures an even seal around the periphery of the door  2  and prevents any dimpling or deforming of the door that would compromise the seal. The sealing mechanism  23  comprises a circular flange  5 , a vertical bar  7 , a horizontal bar  14 , and a horizontal crossbar  6 . The circular flange  5  may be attached to the face of the door panel  3  such that the ring is evenly spaced from the outer edge of the door panel. The vertical bar  7  and the horizontal bar  14  span the inner diameters of the circular flange  5 . The vertical bar  7  and the horizontal bar  14  rigidly attach to the interior of the circular flange  5  to provide structural support to the flange. 
     The horizontal crossbar  6  spans the diameter of the circular flange  5  and the tank door  2  as shown in  FIGS. 1 and 3 . A horizontal crossbar brace  54  covers the crossbar  6  to provide further support. The horizontal crossbar  6  rests directly over the horizontal bar  14  but, as shown in  FIG. 1 , it may be positioned so it does not touch the horizontal cross bar. The horizontal crossbar  6  connects to the circular flange  5  via brackets  11 A,  11 B,  32 A, and  32 B. The brackets  11 A and  11 B are welded to the horizontal crossbar  6 . Brackets  32 A and  32 B are welded to the interior edges of the circular flange  5  just above the horizontal bar  14 . The horizontal crossbar  6  attaches to the circular flange  5  via bolting brackets  11 A and  32 A together and bolting brackets  11 B and  32 B together.  FIG. 3  shows bolts  12 A and  12 B connecting the top halves of brackets  11 A,  11 B,  32 A, and  32 B together as well as showing bolts  13 A and  13 B connect the bottom halves of brackets  11 A,  11 B,  32 A, and  32 B together. Brackets  32 A and  32 B are only visible in  FIG. 1 . 
     As shown in  FIG. 6 , a center circular flange lip  52  may be attached to the circular flange  5  in place of the vertical bar  7  and horizontal bar  14  of  FIG. 1 . The lip  52  is welded to the top of the circular flange  5  matching the flange&#39;s circumference and projects inward. The horizontal crossbar  6  connects to the surface of the circular flange lip  52  on opposite sides via brackets  11 A and  11 B. Brackets  11 A and  11 B connect to the outer surface of the lip  52  via bolts  12 A and  12 B. The brackets are also connected underneath the horizontal crossbar  6  to the lip  52  via bolts  13 A and  13 B as shown in  FIG. 7 . The space in the center of the circular flange  5  and the underneath the lip of the flange  52  is completely open exposing the surface of the door panel  3  as seen in  FIG. 6 . 
     Turning to  FIGS. 8 and 9 , an alternative embodiment of the tank door sealing mechanism is shown. The embodiment of  FIGS. 8 and 9  utilizes two vertical bars  55  and  56  and two horizontal bars  57  and  58 . Horizontal bars  57  and  58  are made of three pieces each and extend across the door within the circular flange  5 . The horizontal cross bars  57  and  58  are welded to the inside of the circular flange  5 . Brackets  11 A and  11 B are welded to the horizontal bars  57  and  58  and provide attachment points for the cross bar  6 . Vertical bars  55  and  56  extend inside the diameter of the circular flange  5  across the horizontal bars  57  and  58 . 
     Connecting the horizontal crossbar  6  to the tank door  2  in two places, as shown in  FIGS. 1 ,  6 , and  8 , works to ensure an even seal around the periphery of the door. When the tank door  2  is in the closed position, the horizontal crossbar  6  exerts pressure on the tank door. By connecting the horizontal crossbar  6  to the tank door  2  in two different places on the circular flange  5 , the pressure exerted on the tank door  2  remains balanced around the door ensuring the integrity of the tank door  2  and seal when the tank door  2  is closed. 
     Pressure is exerted on the horizontal crossbar  6  by the lifting assembly  22 A seen in  FIG. 1 , which connects to both ends of the horizontal crossbar  6  next to the outer edges of the tank door  2 . The lifting assembly  22 A, as shown in.  FIG. 2 , facilitates hydraulic raising and lowering of the tank door  2 . The lifting assembly  22 A comprises a cylinder  16 A, a piston  17 A, an upper linkage arm  18 A, a lower linkage arm  19 A, a crossbar linkage arm  21 A, pivot pins or connection points  20 A,  25 A, and  29 A, and rotating pin  31 A. The lifting assembly  22 A is shown in the closed locked position functioning to seal the tank door  2  shut in  FIG. 1 . An identical lifting assembly  22 B may be positioned on the opposite side of vacuum tank  1  as shown in  FIG. 5 . One skilled in the art will recognize that the lifting assembly  22 B ( FIG. 5 ) functions identical to the lifting assembly  22 A as described in  FIGS. 1 and 2 . Lifting assembly  22 A and  22 B work simultaneously to open and close the tank door  2 . The tank door also has a discharge door sealing flange  4  that meets the vacuum tank sealing flange  24  when the door is in the closed and sealed position to help ensure a tight seal. The vacuum tank sealing flange  24  is attached to the vacuum tank  1 . A gasket or rubber seal (not shown) may be attached to either flange to make the seal air tight. 
     In reference to  FIG. 2 , cylinder  16 A, within the lifting assembly  22 A, is rigidly mounted to the vacuum tank  1  via a cylinder mounting hole  26 A. The cylinder  16 A houses a piston  17 A, shown in  FIG. 1 , which is attached via pivot pin  25 A to the lower linkage arm  19 A. The lower linkage arm  19 A attaches to the upper linkage arm  18 A via pivot pin  20 A. The upper linkage arm  18 A is then attached to the crossbar linkage arm  21 A via pivot pin  29 A. The upper, lower, and crossbar linkage arms  18 A,  19 A, and  21 A and piston  17 A contain holes  40 A,  41 A, and  42 A for accepting these pivot pins. The crossbar linkage arm  21 A is rigidly attached to the horizontal crossbar  6 . The lower linkage arm  19 A is also attached to the vacuum tank  1  via a rotating pin  31 A which is welded to the side of the vacuum tank  1 . 
     In operation, the hydraulic cylinder  16 A is at a starting position when the piston  17 A is extended out of the cylinder  16 A, as shown in  FIG. 1 , and the tank door  2  is closed. When the hydraulic cylinder  16 A has been pressurized using hydraulic fluid to retract the piston  17 A into the cylinder  16 A, as shown in  FIG. 2 , the lower linkage arm  19 A extends upwards in direction of the arrow  27 . When the piston  17 A forces the lower linkage arm  19 A to extend upwards, the upper linkage arm  18 A extends upwards as well forcing the tank door  2  open. The tank door  2  is connected to the top of the vacuum tank  1  via a hinge  15 . The tank door  2  extends out from the top of the vacuum tank  1  at the hinge  15  when the tank door  2  is fully opened. Full extension of the linkage arms exposes the interior of the vacuum tank. 
     To close the tank door  2 , the hydraulic cylinder  16 A is pressurized so that the piston  17 A extends from the cylinder  16 A causing the lower linkage arm  19 A to fold backwards about pivot pin  31 A in the direction of arrow  28 A in  FIG. 1 . As the lower linkage arm  19 A begins to fold backwards, the upper linkage arm  18 A collapses forward at pivot pin  20 A, in the direction of arrow  27  in  FIG. 2 . Upper linkage arm  18 A collapses forward until it comes to rest directly on top of the lower linkage arm  19 A as shown in  FIG. 1 . This forward movement also causes the upper linkage arm  18 A to rotate around pivot pin  29 A as it pulls the tank door  2  back to a closed position. When the upper and lower linkage arms  18 A and  19 A are completely folded, the tank door is sealed and the upper linkage arm  18 A sits substantially parallel to the crossbar linkage arm  21 A. The lower linkage arm  19 A extends and retracts to initiate the opening and closing of the tank door  2  all while rotating around the rotating pin  31 A. 
       FIG. 1  also demonstrates how the lower linkage arm  19 A and upper linkage arm  18 A fold at pivot pin  20 A to rest “over-center” in regards to horizontal line  30 A (also shown in  FIG. 4 ) when the tank door  2  is closed. In this position, the linkage biases the tank door  2  in the closed position should the cylinders  16 A and  16 B fail. Because pivot points  20 A and  20 B are folded and rotated beyond over-center, lower linkage arms  19 A and  19 B cannot rotate or extend in a direction opposite arrows  28 A ( FIGS. 1 &amp; 4 ) and  28 B ( FIG. 5 ) unless they are actively biased in those directions to a point above horizontal line  30 A ( FIG. 4) and 30B  ( FIG. 5 ). As a result, in this position, the door is considered sealed since an active force is required to force the linkage arms back over-center and into the open position. 
     The lifting assemblies  22 A and  22 B respond identically at substantially the same time to fold and rotate the linkage arms over-center to close the door  2 . Together, the assemblies force the tank door  2  against the vacuum tank  1  by applying a load upon the tank door  2  that is opposed only by forcing the linkage arms back over-center. The cylinder is shown in  FIGS. 1 ,  2 ,  4 , and  5  as being mounted horizontally to the side of the vacuum tank  1 ; however, one skilled in the art would appreciate that this cylinder may also be mounted in a more vertical position closer to the tank door  2  because this position still allows the lifting assembly  22 A and  22 B to rotate to over-center. 
     Turning now to  FIG. 3 , a front view of the sealed tank is shown.  FIG. 3  illustrates the position of the brackets  11 A and  11 B with regard to the horizontal crossbar  6 .  FIG. 3  also shows a collection tank inlet  8  positioned just above the vertical bar  7  outside of the center circular flange  5 . When a vacuum is produced in vacuum tank  1 , a vacuum air stream may be pulled through the vacuum tank inlet  8 . When inlet  8  is not closed off by a plug  33 , the inlet may be connected to a hose (not shown) leading to digging tools (not shown). One skilled in the art will also recognize that the vacuum tank inlet  8  may also be placed on either side of the vacuum tank  1 . Placing the vacuum tank inlet  8  on the face of the tank door  2  may provide for less expensive repair of the inlet  8  by only having to fix the tank door  2  rather than the entire vacuum tank  1 .  FIG. 3  also shows two sight eyes  60  on the tank door which allow the operator to view the level of fluid within the tank. A safety strobe light  61  is also shown at the top of the tank. 
       FIG. 3 , as well as  FIGS. 1 ,  2 ,  4 , and  5 , show a flange  36  on the face of the tank door  2 . The flange  36  supports a gate valve  9  to allow draining of the liquid portion of the slurry in the vacuum tank  1  without requiring the door to be opened. Gate valve  9  may also be used to introduce air into the vacuum tank  1  to reduce the vacuum in the tank so that the door may be opened. A sediment collector  35  is also shown in  FIG. 3  attached to the side of the vacuum tank  1 . The sediment collector  35  collects any debris or rocks that are pulled into the vacuum tank  1  via the vacuum tank inlet  8 . 
       FIG. 4  represents another side diagrammatical view of the vacuum tank  1  with the vacuum tank door  2  sealed closed. This view shows the same side shown in  FIGS. 1 and 2 . However, in  FIG. 4  a guard bracket  37 A is shown. The cylinder  16 A and piston  17 A are not shown in  FIG. 4  because they are positioned behind the guard bracket  37 A. The guard bracket  37 A is used to support and protect various components of the lifting assembly. An identical guard bracket  37 B is shown on the opposite side of the vacuum tank in  FIG. 5 .  FIG. 4  also shows the shut off lid  62  utilized to stop suction within the tank with the tank is full. A cylinder plate  63  is also shown at the top of the tank. 
     Turning to  FIG. 5 , the opposite side of the tank shown in  FIGS. 1 ,  2  and  4  is shown. The lifting assembly  22 B shown is identical to the lifting assembly  22 A shown in  FIGS. 1 ,  2 , and  4 . Cylinder  16 B and piston  16 B are not shown; rather, the guard bracket  37 B they are disposed behind is shown. As in  FIG. 4 , pivot pin  20 B is shown over-center below the horizontal line  30 B. 
     The above described embodiments of the lifting assemblies  22 A and  22 B and the sealing mechanism  23  provide several advantages. First, rotating the lower linkage arm  19 A and  19 B over-center maximizes the amount of sealing force exerted by the horizontal crossbar  6  upon the tank door  2 . Second, placing the lower linkage arms in the over-center position biases the door in the closed position. Third, the ability of the linkage arms  18 A,  18 B,  19 A, and  19 B to fully extend allows the tank door  2  to open widely making the interior of the vacuum tank  1  easily accessible. 
     Finally, connecting the horizontal crossbar  6  in two different places to the circular flange  5  by brackets  11 A,  11 B,  32 A, and  32 B, ensures that the horizontal crossbar  6  exerts a balanced force on the tank door  2 . This reduces the likelihood of dimpling or deforming of the tank door  2  that would compromise the door&#39;s seal. Further, connecting the horizontal crossbar  6  in two places to the tank door  2  provides for an even seal around the circumference of the tank door  2 . 
     It should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention. It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.