Abstract:
An automatic screening apparatus for removing debris from a liquid stream includes a drive mechanism mounted to a support frame. A screen connects to the support frame and collects debris while allowing the liquid to flow through. The drive mechanism positions and interchangeably couples to a first carriage assembly and a second carriage assembly. The first carriage assembly includes a rake that removes the collected debris from the screen. The second carriage assembly includes a bucket that removes the debris collected from the rake. A plunger directs the debris from the rake into the bucket. At selected intervals, the drive mechanism decouples from the first carriage assembly and couples to the second carriage assembly, whereupon the second carriage assembly is positioned to dump the bucket. After dumping the bucket, the drive shaft is decoupled from the second carriage assembly and coupled to the first carriage assembly, whereupon the cycle is repeated.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a Non-Provisional Application claiming the benefit of U.S. Provisional Application No. 60/414,112 filed on Sep. 28, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to an apparatus for intercepting and removing debris and trash moved within a liquid stream. In particular, the present invention relates to a self-relieving screening apparatus for intercepting debris and trash flowing through a conduit, pipe, channel, tank or well, and automatically elevating the intercepted trash and debris to a receptacle or conveying system. 
     There exists in the art many examples of self-relieving screening apparatuses for liquids, particularly for waste streams. Such apparatuses typically include complex mechanical drive systems such as cable and pulley systems, chain and sprocket systems, rack and pinion systems, or manual systems of similar design. The complexity of these mechanical drive systems typically involve many moving parts subject to wear and tear, which can lead to high maintenance costs. Also, because self-relieving screening apparatuses are generally located in an unmanned environment, reliability is essential. Reliability is questionable in apparatuses that include drive parts located near or within the waste stream because they tend to malfunction by becoming contaminated, corroded or jammed. 
     SUMMARY OF THE INVENTION 
     An automatic, self-relieving apparatus filters trash and debris from incoming liquid, typically sewage or storm water, flowing in a conduit, pipe or channel. The apparatus utilizes a bar screen and automatic rake in conjunction with a traveling dump bucket to remove the collected trash or debris. The bar screen is positioned within the flow of the liquid such that the debris collects upon the bar screen. At selected intervals, the rake engages the screen to lift and remove the debris. The rake is positionable via a ball screw drive mechanism. Upon the rake collecting and lifting the debris from the bar screen, a plunger directs and compresses the lifted debris into the dump bucket, which is parked at a level above the inflowing stream of liquid. Upon obtaining a selected amount of debris, a transfer mechanism disengages from the rake and engages the dump bucket, whereupon the dump bucket is lifted via the same ball screw drive mechanism to a predetermined dump height. At the predetermined height, the dump bucket is rotated up to 160 degrees to dump the debris. Upon dumping the debris, the ball screw drive is reversed and the dump bucket is returned whereupon the transfer mechanism disengages from the bucket and once again engages to the rake. The operation may then be repeated. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a debris removal system of the present invention. 
         FIG. 2  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
         FIG. 3  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
         FIG. 4  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
         FIG. 5  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
         FIG. 6  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
         FIG. 7  is a partial perspective view of a transfer mechanism engaged to a dump carriage of the present invention. 
         FIG. 8  is a partial perspective view of the transfer mechanism engaged to a rake carriage of the present invention. 
         FIG. 9  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
         FIG. 10  is a cross-sectional view of the debris removal system of the present invention taken along lines A—A in FIG.  1 . 
     
    
    
     DETAILED DESCRIPTION 
     A debris removal system of the present invention is generally indicated at  10  in FIG.  1 . The debris removal system  10  generally comprises a support frame structure  12 , a bar screen  14  for the containment of debris  16 , a reciprocating rake  18  to clean the bar screen  14 , a bucket  20  for transporting the debris  16  to a separate system  100 , and a plunging apparatus  22  to direct the debris from the rake  18  into the dump bucket  20 . The bar screen  14  and the rake  18  are similar to those fully described in U.S. Pat. No. 4,792,394 entitled “Bar Screen Apparatus,” U.S. Pat. No. 4,917,796 entitled “Lift with Automated Dump” and U.S. Pat. No. 5,032,263 entitled “Bar Screen and Rake Apparatus,” all issued to Rudzinski and commonly assigned to Applicant, all of which are hereby incorporated herein by reference. 
     The frame structure  12  includes an upper portion  24  and a lower portion  26 . The upper portion  24  includes first and second channel members  28 , spaced apart and connected by an upper cross member  30 . Disposed upon and between each channel member  28  is the plunging apparatus  22 , a rake carriage  42  for positioning the rake  18  and a dump carriage  32  for transporting the dump bucket  20 . The lower portion  26  of the frame  12  includes first and second support members  34 , spaced apart and connected at terminal ends by a lower cross member  36 . Opposing ends of the first and second support members  34  attach to the channel members  28 . The lower portion  26  of the frame structure  12  is generally submerged within the flowing stream when positioned within the conduit, pipe or channel. Preferably, and for the most part, the upper portion  24  is not submerged, nor is the upper portion  24  in constant direct contact with the stream to be cleaned. In so doing, all moving parts, with the exception of the rake  18 , are located above water level which reduces corrosion. 
     Disposed between the first and second support members  34  is the bar screen  14 . The bar screen  14  consists of a plurality of flat bars  38  disposed in closely-spaced parallel relation for defining a plurality of narrow, elongated flow openings  40  therebetween. The bars  38  may be positioned between zero to forty-five degrees relative to the direction of the flow stream. A dead plate  41  is mounted between the channel members  28  immediately above the screen  14  for the purpose of preventing solids from dropping on the downstream side of the screen  14  during the raking and removal process. 
     The rake  18  attaches to the support frame  12  by means of the rake carriage  42  which slidably engages the channel members  28 . The rake carriage  42  is positionable between a home position  44 , as illustrated in  FIG. 2 , and a raised position  46 , as illustrated in FIG.  3 . The rake carriage  42  includes a cross-member  48  having downwardly extending legs  50  positioned at terminal ends. Opposing ends of each leg  50  attach to opposing terminal ends of the rake  18 . Preferably, the legs  50  are pivotable such that the rake  18  can be brought out of contact with the bar screen  14  as illustrates in  FIG. 4. A  hydraulic cylinder  52  attaches to either leg  50  to position the rake  18  into or out of contact with the bar screen  14  by urging the leg  50  to pivot in a selected direction. On an upward raking stroke wherein the rake carriage  42  travels from the home position  44  to the raised position  46 , the rake  18  is positioned to be in contact with the bar screen  14  so that it may remove the debris  16  collected thereon. At the end of the raking stroke wherein the rake carriage  42  is positioned at the raised position  46 , the hydraulic cylinder  52  is activated, positioning the rake  18  out of engagement with the bar screen  14  and the carriage  42  is lowered back to a home position  44 . This is done so that debris  16  accumulated on the bar screen  14  during the upward raking stroke after the rake  18  has passed is not pressed by an underside of the rake  18  on the downward return stroke. Upon reaching the home position  44 , the hydraulic cylinder  52  is once again activated thereby positioning the rake  18  into engagement with the bar screen  14  and preparing the rake  18  for another upward raking stroke. 
     To remove debris  16  and screenings carried upwardly by the rake  18  during a raking stroke, the plunging apparatus  22  is provided. The plunging apparatus  22  includes a push blade  54  supported by arms  56  attached to and extending away from the channel members  28 . The push blade  54  is driven by a hydraulic cylinder  58  which positions the push blade  54  between a home position ( FIG. 3 ) and a fully extended position as illustrated in FIG.  5 . The push blade  54  pushes and compresses the debris  16  into the dump bucket  20 . A sensor  60  connected to the cylinder  58  monitors the force needed to push and compress the debris  16  into the bucket. The sensor is also connected to a Program Logic Controller (PLC)  62  which monitors the force exerted by the push blade  54 . 
     As the rake  18  approaches the discharge location during its upward raking stroke, the hydraulic cylinder  58  is activated to extend the push blade  54  toward the rake  18 . At the top of the upward stroke of the rake  18 , the push blade  54  pushes the debris  16  from the dead plate  41  resulting in the debris  16  being deposited into the dump bucket  20 . The dump bucket  20  is preferably perforated to allow excess water to sieve through, as the push blade  54  continues to travel partially within the bucket  20  to compress the debris  16  therein. Upon reaching the fully extended position, the hydraulic cylinder  58  is reversed and the push blade  54  is brought back to the home position, as illustrated in FIG.  6 . Nozzles (not shown) may be attached to the push blade  54  which when activated are capable of washing either the rake  18 , the dump bucket  20 , the screenings  16  or any combination thereof. The raking cycle then repeats by returning the rake carriage  42  to the home position ( FIG. 4 ) and positioning the rake  18  into contact with the bar screen  14  ( FIG. 2 ) in preparedness for upward travel to remove debris  16  retained upon the bar screen  14 . 
     Upon the dump bucket  20  being sufficiently filled with debris  16 , typically after several raking cycles, the force needed to extend the push blade  54  into the bucket  20  becomes too great and the PLC  62  attached to the pressure sensor  60  activates a transfer mechanism  64 . The transfer mechanism  64 , as illustrated in  FIGS. 7 and 8 , allows for interchangeable connection of a drive mechanism  66  between the rake carriage  42  and the dump carriage  32 . The drive mechanism  66  includes a ball screw drive  68  rotatably supported at an upper end by a bearing  70  mounted on a bracket  72  attached to the cross brace  30  of the upper portion  24  of the support frame  12 . For driving the ball screw drive  68 , the upper end thereof is connected by a coupler  74  to a hydraulic motor  76  mounted upon the bracket  72 . The ball screw drive  68  operatively engages a ball nut  80 . The ball nut  80  is adapted for slidable engagement with the transfer mechanism  64  to interchangeably couple the drive mechanism  66  to either the rake carriage  42  or the dump carriage  32 . 
     The transfer mechanism  64  includes a hydraulic cylinder  82  operably connected to a transfer slide  84  by means of an attaching rod  86 . The attaching rod  86  disposes within an aperture  88  located within the transfer slide  84  to operably connect the hydraulic cylinder  82  to the transfer slide  84 . The transfer slide  84  encases the ball nut  80  within a slotted cavity  90  which permits translational movement of the transfer slide  84  about the ball nut  80 . The transfer slide  84  thus continually engages the ball screw drive  68 , and can be alternately coupled to either the rake carriage  42  or the dump carriage  32 . To alternately couple the transfer slide  84  to either the rake carriage  42  or dump carriage  32 , the transfer mechanism  64  further includes mateable pins  92  and receiving members  94 . 
     The mateable pins  92  extend from the transfer slide  84  while the receiving members  94  attach to the rake carriage  42  and the dump carriage  32 . Preferably, each receiving member  94  is substantially C-shaped to receive the respective pins  92  extending from the transfer slide  84 . When the pins  92  adjacent the rake carriage  42  are disposed within and engage to the receiving members  94  of the rake carriage  42 , the transfer slide  84 , and thus the ball screw drive  68 , is coupled to the rake carriage  42 . Upon urging the transfer slide  84  toward the dump carriage  32 , pins  92  of the transfer slide  84  adjacent the rake carriage  42  disengage from the receiving members  94  attached to the rake carriage  42  and the pins  92  of the transfer slide  84  adjacent the dump carriage  32  dispose within and engage the receiving members  94  of the dump carriage  32 , thereby coupling the transfer slide  84 , and thus the ball screw drive  68 , to the dump carriage  32 . It should be noted, however, that it is well within the scope of the present invention to interchange the positions of the receiving members  94  and pins  92  to accomplish engagement and coupling of the transfer slide  84  to either carriage  32  or  42 . Coupling and decoupling of the transfer mechanism  64  can be accomplished only when both the rake carriage  42  and the dump carriage  32  are positioned at their respective home positions. The home position of the dump carriage  32  includes the bucket  20  positioned for receiving debris  16  from the rake  18 . 
     During the raking cycle, the transfer mechanism  64  engages the rake carriage  42  to couple the rake carriage  42  to the drive mechanism  66  whereby the rake  18  may be raised and lowered relative to the screen  14  with reciprocal movement. Operation of the hydraulic motor  76 , and hence raising and lowering of the rake carriage  42 , may be controlled by respective upper and lower movement limit switches  95 , which are engageable with the transfer slide. Also, regardless whether the transfer mechanism  64  is engaged to the rake carriage  42  or the dump carriage  32 , raising of the transfer mechanism  64  disengages the attaching rod  86  from the transfer plate  84 . The attaching rod  86  is only capable of horizontal movement, and not vertical movement, and thus can only be positioned when disposed within the aperture  88  of the transfer plate  84 . 
     As described, upon the dump bucket  20  being sufficiently filled with debris  16 , the force needed to extend the push blade  54  into the bucket  20  becomes too great and the PLC  62  attached to the pressure sensor  60  activates the transfer mechanism  64  upon the rake carriage  42  returning to the home position  44 . The PLC  62  activates the hydraulic cylinder  82  operably connected to the transfer slide  84  whereby the transfer slide  84  disengages from the rake carriage  42  and engages to the dump carriage  32  as illustrated in FIG.  9 . Upon completion of the coupling, the ball screw drive  68  may then be activated to initiate the dump cycle to position the dump carriage  32  to empty the bucket  20 . 
     Attachment of the bucket  20  to the dump carriage  32 , along with the dumping cycle of the bucket  20 , is essentially similar to that fully described in U.S. application Ser. No. 10/271,354, Publication No. 2003/0089088, which is hereby incorporated herein by reference. The dump carriage  32  includes an upper member  96  and a lower member  98  joined at terminal ends by first and second vertical members  99 . The dump bucket  20  pivotally attaches to the lower member  98  and is disposed between the first and second vertical members  99 . Upon raising the dump carriage  32  to a selected height, the dump bucket  20  is permitted to rotate from a resting position to a fully dumped position as illustrated in FIG.  10 . 
     Initiation of the entire cleaning cycle begins with the rake carriage  42 , the dump carriage  32  and the plunger  54  at their respective home positions. When the dump carriage  32  is at the home position, the dump bucket  20  rests upon the lower member  98 , and is in position for receiving debris from the rake  18  during the raking cycle. Operation of the plunger  54  coincides with the raking cycle to push the debris  16  from the raised rake  18  into the dump bucket  20 . As mentioned, the dump bucket  20  is preferably perforated such that the plunger  54  can compress the debris  16 , and excess water is permitted to sieve through the dump bucket  20 . During the raking cycle, the drive mechanism  66  is coupled to the rake carriage  42  ( FIG. 7 ) to raise and lower the rake  18 . 
     Upon the dump bucket  20  being filled to capacity, which is monitored by the PLC  62 , the transfer slide  84  disengages from the rake carriage  42  while at its home position and couples to the dump carriage  32  to begin the dump cycle (FIG.  8 ). The dump cycle begins with the PLC  62  activating the ball drive mechanism  66  to raise the dump carriage  32 . At the raised discharge station, the bucket  20  is dumped as described in U.S. application Ser. No. 10/271,354, and the debris is deposited on a conveyor  100  or within another bin for further removal. 
     Upon dumping, the drive mechanism  66  is reversed and the dump carriage  32  travels downward to the home position to complete the dump cycle. When the dump carriage  32  travels back to the home position, the hydraulic cylinder  82  urges the transfer slide  84  to disengage from the dump carriage  32  and couple to the rake carriage  42 . The raking cycle may then be repeated, whereby debris  16  is collected from the bar screen  14  by the rake  18  and deposited within the dump bucket  20  by way of the hydraulically controlled plunger  54 . 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.