Abstract:
The emitter attachable to a fluid conduit comprises a fluid inlet portion capable of taking in fluid from the fluid conduit. The fluid from the inlet portion moves to the pressure compensating or reducing portion which comprises a set of teeth which are arranged in a way so as to impede the flow of liquid thereby reducing the pressure. Downstream the pressure compensating portion is the output portion which communicates with an aperture in the fluid conduit to enable distributing the fluid to the environment. The base of the emitter is flexible allowing movement of the base by virtue of the pressure gradient. When the pressure of the fluid is reduced in the pressure compensating portion, a pressure gradient is created across the base and this result in the fluid in the fluid conduit moving the base towards the fluid conduit thereby reducing the volume of the cavity of the emitter.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to emitters for drip irrigation, and specifically to pressure compensating emitters. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conventionally, a drip tube product with a continuous flow path with inlets is separated into individual emitters by the design of the inserted ribbon using a crossover. The ribbon is bonded into the main tube via insertion through a crosshead die and then pressed against the tube to bond the ribbon to the tube. An outlet is then laser shot or slit at the appropriate point. This type of process has been used in the irrigation industry by several companies. The flow rates of the products made using this process are dependent on pressure in the desired range of operation. These products are energy efficient and run in a pressure range of 6 to 15 psi. Depending on the design the flow rate of the emitters can fall off as much as 50% or more. 
         [0003]    Hence, there is a need to compensate for pressure and allow for a uniform distribution of water greatly improving crop uniformity and energy usage. 
       OBJECTIVE OF THE INVENTION 
       [0004]    1. It is the primary objective of the present invention to compensate pressure variations of incoming water 
         [0005]    2. It is another objective of the present invention to allow uniform distribution and output of water 
       SUMMARY OF THE INVENTION 
       [0006]    According to an aspect of an invention there is disclosed an emitter for discharging liquid. The emitter comprises an elongated frame such that the periphery encloses a cavity therewith, the periphery enabling attachment of the elongated frame to an interior surface of a fluid conduit. The base is arranged to deflect in response to a pressure differential between a pressure in the cavity and a pressure in a fluid flow passage of the fluid conduit. The emitter further comprises a plurality of intervals disposed in the periphery at a first end of the elongated frame, the plurality of intervals enabling fluid communication between the cavity and the fluid flow passage and arranged to receive fluid from the fluid flow passage. The emitter further comprises a plurality of projections disposed approximately at a middle portion of the elongated frame and extending from the periphery on both sides of the elongated frame towards a center of the cavity. Each of the plurality of projections has a first surface that slopes downwards from the periphery towards the center of the cavity. The plurality of projections are arranged to reduce the pressure of fluid flowing through the cavity and wherein the plurality of projections are arranged to deflect with the deflection of the base. The cavity at a second end is arranged to receive pressure compensated fluid from the middle portion and wherein the cavity is arranged to communicate fluidly through an aperture on the fluid conduit, wherein the first end and the second end are linearly opposite end portions of the elongated frame. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]    Exemplary embodiments of the present invention are described hereinafter with reference to the following drawings, in which: 
           [0008]      FIG. 1  shows an isometric view of an emitter for discharging liquid 
           [0009]      FIG. 2  shows an enlarged view of a plurality of projections in the emitter 
           [0010]      FIG. 3  shows an aperture in a fluid conduit for discharge of fluid 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    Discrete emitters have been produced for a period of time using a silicone diaphragm that deflects under varying pressure onto a metering groove. This metering groove is sufficiently small to allow only a certain amount of water to pass regardless of the pressure. While this technique has been used, the nature of this design can cause plugging and the use of a thermoset silicone is expensive and limits the design of the product. These emitters are also individually molded units and do lend themselves to continuous production easily. A novel approach to solve this problem would be to use a continuously formed ribbon as the emitter and have that ribbon compensate for pressure. By using a special flexible olefin block copolymer; this ribbon can easily be bonded to the main body of the tube. The flexibility of the polymer is only one aspect of the compensation technique. The teeth of the flow path that would normally be bonded to the tube are not in this case bonded but instead a rail that rides slightly above the teeth is bonded to the tube. This allows for varying number of teeth to engage the body of the tube depending on pressure and consequently compensates for pressure. Conventional design techniques require a pressure reduction area or labyrinth prior to the metering groove. This area is also prone to plugging causing variations in the compensation capabilities as well as plugging of the metering groove. The advantage provided by the invention is that the compensation starts at the distal end of the flow path and progresses towards the proximal end as the pressure increases. If there are any debris in the emitter, the backpressure will increase causing the entire flow path to disengage from the main body of the tube causing the debris to pass. The advantage of this design is that when pressure is relieved the flow path again becomes a straight through path flowing over the teeth and allowing any built up debris to pass through. Also during operation if the path becomes clogged the pressure will open the flow path and allow the debris to pass. The unique nature of the polymer allows the bonding of the rails and the flexibility of the teeth of the flow path to both compensate and be clog resistant. 
         [0012]    The design of the flow path described above coupled with the unique characteristics of the olefin block copolymer allow the flowpath to be formed in a very precise manner and be bonded in a unique manner to the main body of the tube. Since both materials are of an olefinic base a strong bond is insured. The design of the teeth is precisely radiused to compensate for the structure of the tube. The teeth can also be tapered along the length of the flowpath to further aid in compensation. To achieve this type of performance requires a combination of precise rotary mold design, product design and polymer properties to work effectively. 
         [0013]    The number of intervals that interact with the fluid flow passage depends on the pressure differential starting at the outlet end and progressing towards inlet at increasing main body pressure channels. 
         [0014]      FIG. 1  shows an isometric view of an emitter  100  for discharging liquid. The liquid that the emitter is capable of emitting can be water or any solution. The emitter  100  can be used for purposes of irrigation and specifically drip irrigation where water or any water based solution has to be supplied to the irrigated area. The solution can be a solution of any water soluble compound in water that is to be supplied to the plants in the irrigated area. 
         [0015]    As illustrated in  FIG. 1 , the emitter  100  comprises an elongated frame  105  with a periphery  110 . The periphery can also be referred to as an edge running completely around the elongated frame  105 . The periphery  110  is higher than a base  115  of the elongated frame  105 . The base  115  runs throughout the entire length of the elongated frame  105 . The periphery  110  running around the elongated frame  105  encloses a cavity  120 . The periphery  110  enables attaching the emitter to an internal surface of a fluid conduit (not shown). The working of the emitter  100  in conjunction with the fluid conduit is described hereinafter. To elaborate, the emitter  100  is fitted or attached to the inside surface or internal surface of the fluid conduit and the fluid from the fluid conduit enters the cavity  120  of the emitter  100  and flows out through an aperture  190  on the fluid conduit, as illustrated in  FIG. 3 .  FIG. 3  shows the aperture  190  in the fluid conduit for discharge of fluid from the emitter.  FIG. 3  illustrates that any fluid conduit can accommodate a plurality of emitters with the plurality of emitters communicating to the environment through a plurality of apertures  190  arranged linearly. 
         [0016]    The emitter  100  comprises a plurality of intervals  125  disposed in the periphery  110  at a first end  130  of the elongated frame  105 . The plurality of intervals  125  enables fluid communication between the cavity  120  and a fluid flow passage (not shown) of the fluid conduit to receive fluid from the fluid flow passage. In other words, when in use, the fluid passes through the plurality of intervals  125  from the fluid flow passage to the cavity  120 . 
         [0017]    The emitter  100  further comprises a plurality of projections or teeth  140  disposed in a middle portion  145  of the elongated frame  105 . The middle portion  145  is disposed between the first end  130  and a second end  150 . The plurality of projections  140  extend from the periphery  110  on both sides of the elongated frame  105  towards the center of the cavity  120 . In other words, the plurality of projections  140  extends towards each other from the periphery  110  on both sides of the elongated frame  105 . The plurality of projections  140  from the opposite sides of the periphery  110  do not touch or contact each other, such that fluid from the first end  130  can flow through the plurality of projections  140  to the second end  150 . Each of the plurality of projections  140  has a first surface  155  that slopes downwards from the periphery towards the center of the cavity  120 . The surface of each of the plurality of projections  140  opposite the first surface  155  is a second surface  160  (as shown in  FIG. 2 ).  FIG. 2  shows an enlarged view of the plurality of projections  140  in the emitter  100 . The second surface  160  is mounted on the base  115  of the elongated frame  105 . 
         [0018]    To elaborate, if the first surface  155  is oriented towards the top, then the second surface  160  is oriented towards the bottom. Alternately, if the first surface  155  is oriented towards the bottom, then the second surface  160  is oriented towards the top. Since the plurality of projections  140  are mounted on the base  115 , a deflection of the base  115  deflects the plurality of projections  140  as well depending on the direction of deflection of the base  115 . The deflection of the base  115  is caused by a pressure gradient between the pressure in the cavity  120  and the pressure in the fluid conduit. To elaborate, if the pressure in the fluid conduit is higher than the pressure in the cavity  120 , then the base  115  is deflected in a direction towards the internal surface of the fluid conduit, such that the cross-sectional surface area and the volume of the cavity is reduced. The plurality of projections  140  in the cavity  120  enables obstruction of the flow of the fluid through the emitter so that the speed and pressure of the flowing fluid is reduced. The pressure of the fluid flowing through the teeth  140  gradually reduces from an initial portion  165  of the plurality of projections  140  to a terminating portion  170  of the plurality of projections  140 . Moreover, the arrangement of the plurality of projections  140  as illustrated in  FIG. 2  provides a flow path that is winding for the fluid which enables a reduction of the speed of flow of the fluid from the initial portion  165  of the teeth  140  to the terminating portion  170  of the teeth  140 . 
         [0019]    When in use, the fluid passing through the plurality of teeth  140  flows into the cavity  120  at the second end  150 . The fluid conduit in the proximity of the second end  150  comprises aperture  190  open to the atmosphere. The pressure compensated fluid flowing into the cavity  120  at the second end  150  egresses out of the aperture  190  in the fluid conduit to the outside atmosphere for irrigation or other suitable purposes. The first end  130  and the second end  150  are linearly opposite end portions of the elongated frame  105 . 
         [0020]    The plurality of intervals  125  are disposed on the periphery  110  on both sides of the elongated frame  105 . The advantage of this arrangement is that fluid can enter the cavity  120  of the elongated frame  105  from both sides of the cavity  120 . The fluid then flows from the first end  130  of the elongated frame  105  to the second end  150  of the elongated frame  105  and flows out of the elongated frame  105 . The plurality of intervals  125  extends from the first surface  155  of the periphery  110  to the base  115  of the elongated frame  105 . There are a set of hemispherical structures  175  mounted linearly on the base  115  of the elongated frame  105  in the first end  130  between the periphery  110 . 
         [0021]    The elongated frame  105  comprises an intermediate portion  180  between the first end  130  and the middle portion  145 . The periphery of the intermediate portion  180  has a width which is greater than a width of the periphery  110  in the first end  130 , the second end  150  and the middle portion  145 . The increased width of the periphery  110  in the intermediate portion  180  reduces width of the cavity  120  of the elongated frame  105  in the intermediate portion  180 . The width of the periphery  110  in the intermediate portion  180  on both sides can increase from an end proximal to the first end to an end proximal to the middle portion. In other words, the width of the cavity is greater at the end proximal to the first end than the width of the cavity at the end proximal to the middle portion. 
         [0022]    The plurality of projections or the teeth  140  are made of the same material as the base  115  and therefore imparts the same flexibility as the base  115 . The teeth  140  are disposed such that they make an angle with the periphery  110 . In other words, they are not arranged normal to the periphery  110 . The teeth  140  are arranged such that they project towards the second end  150 . The teeth from the opposite periphery do not touch each other, thus providing a winding pathway for the fluid to flow from the first end  130  to the second  150 . The fluid when flowing through the winding pathway is reduced in pressure from the inlet pressure existing at the first end  130  to the outlet pressure existing at the second end  150 . 
         [0023]    The pressure of the fluid flowing through the cavity  120  of the elongated frame  105  reduces gradually from the first end  130  to the second end  150 . However, the pressure of the fluid flowing through the fluid flow passage in the fluid conduit is constant. As the pressure reduces along the elongated frame  105  from the first end  130  to the second end  150 , a pressure gradient increases gradually from the first end  130  to the second end  150 . 
         [0024]    Higher the inlet pressure, higher the pressure gradient in the middle portion  100  proximal to the second end  150 . Higher the pressure gradient across the base  115  of the elongated frame  105  in the middle portion  100  proximal to the second end  150 , there will be a greater push by the fluid in the fluid flow passage of the fluid conduit on the base  115  to push the base  115  and the second end towards the interior surface of the fluid conduit. For example, if the inlet pressure is 6 psi, a few teeth in the middle portion  100  proximal to the second end  150  are pushed towards the interior surface of the fluid conduit. For example, if the inlet pressure is 10 psi, more teeth in the middle portion  100  proximal to the second end  150  are pushed towards the interior surface of the fluid conduit. For example, if the inlet pressure is 14 psi, even more teeth in the middle portion  100  proximal to the second end  150  are pushed towards the interior surface of the fluid conduit. This pressure gradient and the subsequent deflection of the base  115  towards the interior surface of the fluid conduit helps in pushing the fluid out of the aperture. 
         [0025]    The second portion  150  has a set of hemispherical balls  180  mounted on the base  115 . 
         [0026]    It is to be understood that the foregoing description is intended to be purely illustrative of the principles of the disclosed techniques, rather than exhaustive thereof, and that changes and variations will be apparent to those skilled in the art, and that the present invention is not intended to be limited other than as expressly set forth in the following claims.