Abstract:
An integral in-line dripper to be used bonded to the internal surface of an irrigation pipe. The dripper has an inlet facing the inside of the pipe and an outlet connected to an exit opening in the pipe wall. The dripper has a flattened shape defined between a first surface with an open meandering channel formed therein, the channel&#39;s inlet being connected to the dripper&#39;s inlet, and a second surface opposite the first surface. The topography of the first surface is so designed that the dripper can be bonded to the internal surface of the pipe in any orientation about a radius of the pipe passing through the first and the second surface, so as to form a flow-restriction labyrinth connected to the outlet of the dripper.

Description:
FIELD OF THE INVENTION 
   This invention relates to irrigation drippers, and more particularly to drippers fitted integrally in irrigation pipes and to methods for production of such pipes. 
   BACKGROUND OF THE INVENTION 
   U.S. Pat. No. 6,039,270 describes an irrigation pipe with internally attached emitters. The emitters are placed in the interior of the pipe at its production phase and are sunken almost totally in the wall of the pipe which is swollen at the location of the emitters. The swellings allow to preserve the internal cross-sectional area of the pipe and thus to avoid excessive hydraulic losses and to reduce the required working pressure for irrigation per unit length of the pipe. The emitters disclosed in U.S. Pat. No. 6,039,270 are round in their plan view or are elongated along the pipe axis. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, there is provided an integral in-line dripper for use bonded to the internal surface of an irrigation pipe. The dripper has an inlet facing the inside of the pipe and an outlet in fluid communication with an exit opening in the pipe wall. The dripper has a flattened shape defined between a first surface with an open meandering channel formed therein, the channel&#39;s inlet being in fluid communication with the dripper&#39;s inlet, and a second surface opposite the first surface. The topography of the first surface of the dripper is so designed that the dripper can be bonded to the internal surface of the pipe in any orientation about a radius of the pipe passing through the first and the second surface. At that, the topography allows the internal surface of the pipe to be bonded tightly to the first surface of the dripper especially in the areas adjacent the meandering channel so as to form a flow-restriction labyrinth with an outlet constituting or being in fluid communication with the outlet of the dripper. 
   According to one aspect of the present invention, the dripper has a means for aligning thereof before the bonding so that its first surface faces the internal surface of the pipe. Preferably, the first and the second surface have different shapes, such that the difference may be used as a means for alignment. 
   In one embodiment of the dripper, the means for alignment is formed as a step, e.g. circular, protruding from the second surface. The circular step may be an annular wall or a cylinder pin, preferably coaxial with an axis of symmetry of the second surface. A cylinder pin protruding from the first surface may be used as well. 
   In another embodiment, the second surface is more convex than the first surface, e.g. dome-shaped, while the first surface is only slightly convex or substantially flat and this difference is used for alignment. 
   Preferably, the dripper&#39;s inlet is a filtering inlet comprising multiple openings in fluid communication with the inlet of the meandering channel. The openings may be disposed on the second surface or on a peripheral surface connecting the first and second surfaces. For example, the filtering inlet may be formed as multiple radial passages on the first surface, starting with the multiple openings and complemented by the internal surface of the pipe. 
   The first surface of the dripper may be, for example, flat, dome-shaped, or part of a cylindrical surface. Preferably, the first surface is substantially isometric in plan view, for example it may have a generally circular symmetry, or be just circular in shape. However, the dripper may be also elongated if its size and the topography of the first surface allow bonding in arbitrary orientation about the local pipe&#39;s radius. 
   In accordance with a second aspect of the present invention, the topography of the second surface is similar to the topography of the first surface, including a second open meandering channel, such that the dripper can be bonded to the pipe with either of the first and second surfaces, in any orientation with respect to a radius of the pipe passing through the first and the second surface. 
   Preferably, the dripper has a filtering inlet comprising multiple openings as described above, formed as multiple radial passages on both the first and the second surface so as to be complemented by the internal surface of the pipe after bonding. 
   The dripper may be formed with the second surface as a mirror image of the first surface. Alternatively, the second surface may be identical to the first surface and disposed so that recesses on the second surface are matching protrusions on the first surface and vice-versa. 
   In accordance with a third aspect of the present invention, there is provided an irrigation pipe with integral in-line drippers of flattened shape bonded to the internal surface of the pipe with a first surface of the drippers. The first surface has an open meandering channel formed therein and closed tightly by the internal surface. The flattened shape is substantially isometric in plan view, or is elongated but at least some of the drippers are bonded with their longer dimension non-parallel to the axis of the pipe. 
   The drippers of the present invention allow mass production in simple molds or dies. Even more important, as the specially designed form allows bonding in arbitrary orientation, the drippers may be fed to the bonding position with little or no alignment and thus achieve high rate of pipe production. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to understand the invention and to see how it may be carried out in practice, some embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective sectional view of a dripper bonded into an irrigation pipe in accordance with the present invention 
       FIGS. 2A and 2B  are perspective top and bottom views of a dripper with an aligning ring; 
       FIG. 3  shows the process of dripper alignment in the feeder of an extrusion installation, using an aligning ring; 
       FIG. 4  is a top perspective view of a dripper with dripper outlet formed as an aligning pin; 
       FIG. 5A  is a bottom view of a dripper with an aligning step; 
       FIG. 5B  is a top perspective view of the dripper in  FIG. 5A ; 
       FIG. 6A  is a top view of a dripper with aligning asymmetry; 
       FIG. 6B  is a side view of the dripper in  FIG. 6A ; 
       FIG. 7  shows the process of dripper alignment in the feeder of an extrusion installation using aligning asymmetry; 
       FIG. 8  is a perspective view of a dripper with mirror symmetry allowing arbitrary bonding in the irrigation pipe of either labyrinthed face; 
       FIG. 9A  is a top view of another dripper, with circular symmetry, allowing arbitrary bonding in the irrigation pipe; and 
       FIG. 9B  is a cross-sectional view of the dripper in  FIG. 9A . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1 , there is shown an integral in-line dripper  10  according to the invention, bonded during the extrusion process to an extruded irrigation pipe  12 , at the internal surface  14  of the pipe. 
   With further reference to  FIGS. 2A and 2B , the dripper  10  has a top surface  16  designed for bonding to the internal surface  14  of the pipe  12 , and a bottom surface  18  facing the inside of the pipe. The top surface  16  and the bottom surface  18  are connected by a peripheral surface  20 . It will be appreciated that the terms “top” and “bottom” are purely conventional and pertain only to the orientation shown in  FIG. 1 . 
   The dripper  10  further has a meandering channel  22  carved in the top surface  16  of the dripper. The channel  22  has an inlet  24  and an outlet  26 . When the dripper is bonded in the pipe, the meandering channel  22  is covered by the internal surface  14  of the pipe to form a labyrinth, and an outlet  27  is formed in the pipe wall, aligned with the outlet  26  of the labyrinth. It will be appreciated that the top surface  16  must allow tight bonding of the pipe wall adjacent the meandering channel  22 , so as to ensure that the labyrinth has closed cross-section. 
   The dripper  10  further has a plurality of openings  28  in the peripheral surface  20 , formed as radial passages between ribs  30 , in fluid communication with the inlet  24  of the channel  22 . When the dripper  10  is bonded to the pipe wall and the passages are covered by the internal surface of the pipe, these openings constitute a distributed filtering inlet. 
   The dripper  10  has an annular wall (ring)  32  protruding from the bottom surface  18 , which is used as a means for alignment. With reference to  FIG. 3 , the drippers  10  come to a feeder  50  in arbitrary orientation. A rotary ring  52  drags the drippers, by frictional force, along a qualifying ring  54  towards a rejection cam  56 . Between the qualifying ring  54  and the rotary ring  52  there is a gap  57  adapted to accommodate the thickness of the dripper but not the ring  32 . As a result, drippers oriented with the ring  32  upwards pass under the rejection cam  56  and proceed past a guiding rail  58  towards the extruder. Drippers with different orientation, as denoted by  10 ′, are rejected back into the feeder. Alternatively, in a vibratory bowl system, the vibratory force will move the drippers along the ring  52  and against the ring  54  which will be stationary relative to each other. The rejection cam  56  will operate in the same manner as above. 
   The dripper  10 , as well as all other drippers described below have more or less flattened shape such that their smallest dimension “d” is perpendicular to the pipe internal surface when bonded thereto. Their plan form, i.e. the projection along that smallest dimension, or the contour when viewed from the bottom or the top surface, is circular, with diameter not exceeding the diameter of the pipe, assuming a circular pipe cross-section. However, the plan form may be just with approximately equal dimensions in all directions (isometric) or with circular symmetry. Even an elongated plan form may be used, if its longer dimension is about the pipe diameter or less. The dripper plan form and the top surface topography are designed to allow bonding of the dripper to the pipe wall in any orientation about a pipe radius R passing through the center of the top surface. 
   The dripper  10  and some other drippers described below have a means for alignment of the dripper during pipe manufacture to ensure that its top surface faces the internal surface of the pipe before bonding. If the dripper has an axis of symmetry, the alignment means is preferably coaxial with that axis. 
     FIG. 4  shows a dripper  35 , similar to the dripper  10  except that its alignment means is in the form of cylindrical pin  29  at the top surface  16 . The pin is combined with the dripper outlet  26  on the top surface  16 . 
     FIGS. 5A and 5B  show a dripper  40  where the filtering inlet is disposed on the bottom surface  18 . A plurality of openings  42  are formed at crossings of parallel channels  44  made on the bottom surface  18 , with an annular channel  46  made on the top surface beside the meandering channel. In this case, a circular step  48  at the bottom surface  18  is used as a means for alignment. 
     FIGS. 6A and 6B  show a dripper  60 , similar to the dripper  40 , with the filtering inlet disposed on the bottom surface  68 . Similar elements of the dripper  60  have the same numbers as the elements of the dripper  40 . In this case, the bottom surface  68  is dome-shaped, which though having no step can still be used as a means for alignment. 
   The process of alignment of the dripper  60  is shown in  FIG. 7 . The feeder  50  is essentially the same as that shown in  FIG. 3 , with a rotary ring  52 , a qualifying ring  54 , and a rejection cam  56 . Between the qualifying ring  54  and the rotary ring  52  there is a gap  57  adapted to accommodate the thin edge of the dripper  60 . The drippers oriented with the dome-shaped surface  68  upwards pass under the rejection cam  56 , while drippers with opposite orientation, as denoted by  60 ′, are rejected back into the feeder. 
   It will be appreciated that any difference of shape between the top and the bottom surface of the dripper may be used for selection of properly aligned drippers in the feeder. 
   Drippers according to the present invention may have no means and no need to be aligned before bonding to ensure that their top surface faces the pipe wall. With reference to  FIG. 8 , there is shown an integral in-line “double-faced” dripper  70  for irrigation pipe, where each of the top surface  16  and the bottom surface  18  is adapted for bonding to the internal surface of the pipe. The dripper  70  has two meandering channels  22  and  72 , at the top and at the bottom surfaces, and two filtering inlets with openings  28  and  78  respectively. Owing to the flattened shape of the dripper, during the pipe manufacturing process, the dripper will always assume a position where one of its top and bottom surfaces faces the pipe wall, without special aligning means. Such dripper can be bonded to the pipe surface with either of the top and the bottom surfaces. In the example shown in  FIG. 8 , the dripper is made with the bottom surface as mirror image of the top surface. 
   In  FIGS. 9A and 9B , there is shown another integral in-line double-faced dripper  80  where both the top surface  16  and the bottom surface  18  are adapted for bonding to the internal surface  14  of the pipe. Here the whole top surface  16  including the meandering channel  22  and the outlet  26  is identical to the bottom surface but is so designed and disposed that recesses on the bottom surface match protrusions on the top surface and vice-versa. In fact, the topography of the bottom surface may be obtained by rotation of the top surface about the axis X. 
   The topography of the top surface (the surface which must be bonded to the pipe) may be flat, convex (dome-shaped), etc. Indeed there is no need that the top surface exactly matches the inner cylindrical surface of an extruded pipe. But the design has to be such that, in the moment of bonding, when the extruded pipe is soft and flexible, it can accommodate the top surface at any orientation thereof. 
   In all the above embodiments, the plan form of the dripper is circular but it may have any shape with circular symmetry or with approximately equal length and width (isometric). As mentioned above, however, the largest dimension of the plan form is critical, so even an elongated shape may be used if it can be accommodated transversely to the pipe axis. The circular shape has the advantage to roll smoothly in the feeder and to allow faster alignment along the path to the extruder. The topography of the top surface, the plan form of the dripper and the layout of the filtering inlet, the meandering channel and the outlet should allow the dripper to be tightly bonded to the pipe wall in any orientation with respect to the pipe axis. 
   Though all the explanations have been presented with respect to dippers designed for bonding in an extruded pipe, such drippers may be used with pipes manufactured by any known technology. 
   Although a description of specific embodiments has been presented, it is contemplated that various changes could be made without deviating from the scope of the present invention. For example, means for alignment of the dripper before feeding to the extruded pipe may be such difference of shape as different roughness of the top and the bottom surface.