Drainage element and method and machine for making same

Abstract

The drainage element is made with a tubular membrane that encasing a mass of discrete aggregate. The membrane being gathered together at each end thereof, is water-permeable and has a plurality of interstices characterized in being of a size for the passage of water therethrough and the filtering of fine particles of solid material from the water passing through the membrane. A short length of pipe may be fabricated into one end only of the drainage element to provide for a hook-up to a sewage system or other system.

1 . A drainage element comprising
 a mass of discrete aggregate defining passageways for a flow of fluid therethrough;   a tubular membrane encasing said mass of discrete aggregate, said membrane being gathered together at each end thereof and being water-permeable and having a plurality of interstices characterized in being of a size for the passage of water therethrough and the filtering of fine particles of solid material from the water passing through said membrane; and   tie means closing around each gathered end of said membrane to retain said aggregate therein.   
   
   
       2 . A drainage element as set forth in  claim 1  wherein said membrane has a grab tensile strength of 61/61 lbf as measured under ASTM D-5034 and a grab elongation to break in % of 45/50 as measured under ASTM D-5034. 
   
   
       3 . A drainage element as set forth in  claim 1  where said membrane is made of spun bonded non-woven polyester. 
   
   
       4 . A drainage element as set forth in  claim 1  wherein said membrane has at least a pair of overlapped longitudinal edges adhesively secured to each other. 
   
   
       5 . A drainage element as set forth in  claim 1  wherein said membrane has at least a pair of sewn together longitudinal edges. 
   
   
       6 . A drainage element as set forth in  claim 1  further comprising a pipe extending from within said mass of aggregate and beyond one end of said tubular membrane, said pipe being of a length less than the length of said tubular membrane. 
   
   
       7 . A drainage element as set forth in  claim 5  further comprising a screen disposed over an end of said pipe within said mass of aggregate for blocking entry of said aggregate into said pipe. 
   
   
       8 . A drainage element as set forth in  claim 5  wherein said tie means at said one end of said tubular membrane is secured about said pipe. 
   
   
       9 . A drainage element as set forth in  claim 1  further comprising a pipe extending from within said mass of aggregate and beyond each end of said tubular membrane. 
   
   
       10 . A drainage element as set forth in  claim 1  wherein said membrane is embossed to increase the surface area thereof. 
   
   
       11 . A drainage element comprising
 a mass of discrete aggregate defining passageways for a flow of fluid therethrough;   a tubular membrane encasing said mass of discrete aggregate;   a pipe extending from within said mass of aggregate and beyond one end of said tubular membrane, said pipe being of a length less than the length of said tubular membrane.   tie means closing around each end of said membrane to retain said aggregate therein.   
   
   
       12 . A drainage element as set forth in  claim 10  further comprising a screen disposed over an end of said pipe within said mass of aggregate for blocking entry of said aggregate into said pipe. 
   
   
       13 . A drainage element as set forth in  claim 10  wherein said tie means at said one end of said tubular membrane is secured about said pipe. 
   
   
       14 . A drainage element as set forth in  claim 10  wherein said membrane is embossed to increase the surface area thereof. 
   
   
       15 . A method of making a drainage element comprising the steps of forming a longitudinal strip of a membrane into a tubular cross-section about a longitudinal axis thereof with a pair of longitudinal edges disposed in overlapping relation to each other, said membrane characterized in being of a size for the passage of water therethrough and the filtering of fine particles of solid material from the water passing through said membrane;
 securing said longitudinal edges together to define a tubular sleeve;   closing one end of the sleeve;   moving said sleeve along a linear path while filling said sleeve with aggregate; moving a pipe coaxially into a rear of said sleeve while continuing to fill said sleeve with aggregate; and   closing the opposite end of said sleeve about the pipe to form a drainage element.   
   
   
       16 . A method as set forth in  claim 15  further comprising the step of placing a longitudinal bead of adhesive between said longitudinal edges of said membrane and pressing said edges together to bond said edges to each other. 
   
   
       17 . A method as set forth in  claim 15  further comprising the step of placing a screen over an open end of said pipe prior to said step of closing one end of said sleeve. 
   
   
       18 . An apparatus for making a drainage element comprising
 a tube for passing a flow of aggregate therethrough;   a forming collar for shaping a continuously supplied membrane strip having a pair of longitudinal edges into a sleeve about said tube with the longitudinal edges thereof in overlapping relation to receive a flow of aggregate therein;   first means for securing the overlapped edges of the strip together;   second means spaced from said tube for intermittently applying tie means about the sleeve;   third means for moving a flow of aggregate through said tube for filling the sleeve with aggregate;   fourth means for moving the sleeve from said tube during filling of the sleeve with aggregate; and   drive means for intermittently moving a pipe coaxially through said tube into a rear of the sleeve while filling the sleeve with aggregate.   
   
   
       19 . An apparatus as set forth in  claim 18  wherein said first means adhesively secures the overlapped edges of the strip together. 
   
   
       20 . An apparatus as set forth in  claim 19  wherein said first means includes at least one roller for pressing the overlapped edges of the strip together. 
   
   
       21 . An apparatus as set forth in  claim 18  further comprising a cutting means for cutting through the strip and pipe.