Abstract:
An irrigation ditch liner system comprises a plurality of liner sections including at least one straight conduit section and one corrugated conduit section, each conduit having a semi-cylindrical body portion defining a conduit interior diameter, vertical walls extending from the semi-cylindrical body portion, and end sections having extending end flanges with an interior diameter greater than said conduit interior diameter. A connecting joint is provided with an outer wall and an inner wall, the inner wall having a interior diameter the same as the conduit interior diameter, where the outer wall of the connecting joint further defines a depending lip that captures the end flanges between the inner wall and the outer wall of the connecting joint.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to irrigation systems and, more particularly, to liners for irrigation ditches. 
     In many parts of the world, irrigation of farmland is done by diverting water from rivers and streams, and the like, through ditches to the land to be watered. These ditches may be many miles in length and substantial maintenance is required on natural ditches, i.e., ditches with earth walls. Where the sources of the irrigation water are mountain streams, the ditches may meander in rugged country to reach the many fields that are irrigated by a single ditch. 
     It will be appreciated that natural ditches deteriorate throughout the year. Ditch walls collapse; debris fills the ditch when water is not flowing. In addition, substantial water is lost by absorption through the dirt walls. Also, animals burrow through earthen ditch banks, with a resulting loss of water. 
     Where the irrigation ditch is in flat, accessible ground, it is possible to line the ditch with a permanent material, such as concrete. This requires, however, substantial equipment for delivering and forming the concrete to the ditch. Concrete lined ditches are also very expensive to construct. It is desirable to provide a ditch liner that can be installed relatively inexpensively and in remote locations. 
     Accordingly, it is an object of the present invention to provide a transportable ditch liner that can be readily installed with simple tools. 
     It is another object of the present invention to provide a transportable, lightweight ditch liner that can be readily conformed to the path of existing natural irrigation ditches. 
     Many objects, advantages and novel features of the irrigation ditch liner will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     SUMMARY OF THE INVENTION 
     To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the apparatus of this invention may comprise an irrigation ditch liner system. The irrigation ditch liner system comprises a plurality of connectable liner sections including at least one straight conduit section and one corrugated conduit section, each conduit having a semi-cylindrical body portion defining a conduit interior diameter, integral vertical walls extending from the semi-cylinrical body portion, and end sections having extending end flanges with an interior diameter greater than said conduit interior diameter. 
     In a preferred embodiment, a connecting joint is provided with an outer wall and an inner wall, the inner wall and the outer wall having converging end portions to engage extending end flanges of adjacent liner sections, where the inner wall has a diameter substantially the same as the conduit diameter to form a smooth connection region. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 is an isometric illustration of a rigid, straight ditch liner conduit according to the present invention. 
     FIG. 2 is an isometric illustration of a corrugated flexible irrigation ditch liner conduit according to the present invention. 
     FIG. 3A is an isometric illustration of joint for connecting adjacent conduit sections. 
     FIG. 3B is a cross-section view of an assembled liner joint. 
     FIG. 3C is a pictorial illustration of a rivet for securing the joint of FIG. 3A to conduit sections shown in FIGS. 1 and 2. 
     FIG. 4 is an isometric view of assembled liner conduits. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with the present invention, an irrigation ditch liner system is provided for installation into existing natural irrigation ditches, i.e., ditches with earth walls, or as a freestanding conduit structure. Individual liner sections provide for in-situ assembly and tie-down of individual conduit sections and for the delivery of irrigation water to selected plots of land. It is expected that the liner system will greatly facilitate cleaning of irrigation ditches and greatly reduce the loss of water through the ditch walls. 
     FIG. 1 is an isometric illustration of rigid, straight conduit  10  of the irrigation liner system according to the present invention. Conduit  10  includes a semi-cylindrical portion  12  for placing within existing irrigation ditch paths, where available, and integral vertical sides  14  extending from semi-cylindrical portion  12  to provide additional volume for water flow without increasing the radius of semicylindrical portions  12 . 
     Conduit  10  includes connector flanges  18 ,  22  for use in joining adjacent conduit sections, as further discussed below. Conduit  10  may need to be secured to the ground to maintain the conduit in place when subjected to dimensional variations from thermal expansion and contraction, from forces exerted by flowing water, and from inadvertent contact from humans and animals. Brackets  24 A- 24 D are formed on vertical sides  14  of conduit  10  to provide an attachment capability to secure the conduit and to serve as handles in carrying the liner. Securing devices, such as long rods, tie ropes, and the like, may be inserted through holes in the brackets to secure the conduit to the ground. Brackets  24 A- 24 D are preferably formed integral with upstanding wall portion  14 , but may be formed as individual pieces that are attached to conduit  10  as needed. 
     FIG. 1 also shows longitudinal flanges  26 ,  28  that are formed along vertical sides  14 , generally between tie-down brackets  24 A,  24 B and  24 C,  24 D, respectively. Flanges  26 ,  28  are preferably formed integral with vertical sides  14 , but may be separate longitudinal pieces that are attached to vertical sides  14 . It will be appreciated that variety of bracket and flange configurations may be designed that are within the scope of the present invention and any number of securing devices are within the skill of a mechanical designer so that the exact configuration shown in FIG. 1, and expressly described herein, is not intended to be limiting. 
     FIG. 2 is an isometric illustration of a second conduit  36  for use in the irrigation system of this invention. Conduit  36  is formed of semi-cylindrical corrugated portion  38  having integral vertical corrugated sides  40  integral therewith. In a preferred design, the maximum diameter of the corrugations is less than the outer diameter of straight conduits  10 . Straight conduit portions  48 A,  48 B are provided at end portions of conduit  36  for securing and joining conduit  36  with abutting conduits. As shown and described above for straight conduit  10  in FIG. 1, connector flanges  42 ,  44  extend from straight portions  48 A,  48 B, respectively, for mating with an abutting conduit. Likewise, tie-down brackets  46 A- 46 D are connected to vertical portion  42  along straight portions  48 A,  48 B, either integrally or separately, for use in securing conduit  36  in a selected location. 
     Corrugated conduit  36  sections are required in order to accommodate thermal expansion and contraction throughout the length of an assembled system. For example, if the conduits are formed of conventional plastics, such as high density polyethylene and polyvinyl chloride, with sections having 5 foot, 6 inch lengths, it is estimated that one corrugated conduit  36  will be required for every three straight conduits  10  (FIG.  1 ). The corrugations also provide an inherent flexibility to conduit  36  so that the assembled ditch liner system can follow a meandering irrigation ditch, such as acequias found in many parts of the southwest. 
     Referring now to FIGS. 3A,  3 B and  3 C, there are shown isometric and cross-section views of a connector for connecting abutting conduits and a cross-section of connected conduits, and a rivet for attaching the connector to adjoining conduits, respectively. In a preferred embodiment of the present invention, abutting conduits are connected with minimum flow restrictions or projections that may catch debris in the irrigation flow stream. FIG. 3A depicts connecting joint  50  that is formed by inner wall  52  and outer wall  54  connected by spacer  56 . In accordance with one embodiment of the present invention, inner wall  52  has a diameter generally the same diameter as the inner diameter of adjacent conduits to form a smooth flow surface as shown in FIG.  4 . Rivet holes  58  are provided for rivets  63  (FIG. 3C) to attach connection joint  50  to adjoining conduits. It will be appreciated that holes are formed in conduit sections after the sections are joined with connector  50  in a field installation and rivets  63  are simply snapped into place. 
     FIG. 3B is a cross-section of connector  50  where inner wall  52  and outer wall  54  define middle portions joined by spacer  56 . Inner wall  52  and outer wall  54  then converge to end portions  60 A,  60 B to form resilient surfaces that engage connector flanges (see, e.g., flanges  18 ,  22 , in FIG. 1; flanges  42 ,  44  in FIG. 2) of the conduits. The resilient surfaces act to seal against the connector flanges to minimize water leakage without gaskets, which are hard to align and seal. 
     FIG. 3C is a pictorial illustration of rivet  63  for securing connector  50  (FIGS. 3A,  3 B) to connector flanges formed on conduits  10  (FIG. 1) and  36  (FIG.  2 ). Rivet  63  is designed to merely be pressed into place in the field. 
     FIG. 4 depicts an isometric view of an exploded joint with first conduit connecting flange  18  and second connecting flange  44  to be captured within connecting joint  50  by converging inner wall  52  and outer wall  54 . The converging walls capture offset flanges  18  and  44  so that inner wall  52  is generally flush with the inner walls of the abutting conduits. Spacer  56  forms the seal between flanges  18  and  44 . 
     It will be appreciated that adjacent conduits sections may be connected by additional sections that are not part of the present invention to provide for outputting water onto areas that are to be irrigated. Such sections may take many convenient forms. In the simplest form, connecting joint  50  (FIG. 4) is simply split along connecting ridge  56  and a box is inserted with a gated outlet connection. 
     A wide variety of dimensions and materials may be selected for the irrigation ditch liner system described above. Typical section lengths may be about five feet, six inches, which can be handled by a single person. The section configurations preferably are formed by standard rotational molding techniques so that conventional plastic materials may be used. Rotational processes are well known and are not described herein. 
     The foregoing description of the preferred embodiments of my irrigation ditch liner has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.