Patent Publication Number: US-2003226913-A1

Title: Emitter with pressure compensating fluid control valve

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to in-line fluid distribution emitters.  
       BACKGROUND OF THE INVENTION  
       [0002] Drip and flow-rate controlled leaching systems have various applications in the mining industry. Similarly, drip and flow-rate controlled irrigation systems have a variety of uses in the agriculture and landscape industries. For each situation, it is desirable to control the amount of fluid, such as leaching agents or water, that flows through such a system over a given period of time. Various flow-rate control systems will achieve this result to varying degrees of success, but many such systems do not produce a constant flow rate over a range of system pressures. One example of such a system is an in-line emitter. Furthermore, in-line emitters are sometimes prone to clogging due to contaminates carried by the fluid through the relatively small channels of the emitter.  
       [0003] As a mechanism for controlling flow, currently developed emitters diminish fluid flow rate and pressure by means of hydraulic friction. Fluid is moved through a labyrinth of channels molded into the emitter exterior surface. Hydraulic friction through these channels reduces fluid pressure and flow rate, thereby providing a modicum of control over the rate of fluid distribution. While this method reduces flow rate, it does not provide a stable rate over a wide range of input-flow pressures. Furthermore, these emitters often do not provide identical flow rates between emitters throughout the distribution system. Such systems typically provide an attenuated discharge of varying rate proportional to system pressure. Alternative in-line flow-rate control devices are needed to produce exit-flow pressures, and therefore exit-flow rates, of relatively constant value.  
       [0004] Historically, in-line flow-rate emitters have been susceptible to plugging due to many factors, such as the presence of a variety of particulates in the fluid being distributed. This can be caused by precipitation of leaching chemicals, scale build up due to water hardness and added chemical treatments, introduction of carbon used in treatment processes and the entry of dirt and other debris as a result of drip lines being dragged across a mining site. Particulates may also result from sediment in the irrigation water source or contamination of the irrigation water source. Typically, emitters designed to achieve lower flow-rates are more susceptible to such plugging. The lower the pressure, the lower the flow-rate will be, and the more susceptible the system will be to plugging because of reduced system energy. Plugging can also occur as a result of pressure fluctuations and changes in elevation. Alternative flow-rate control devices are needed to minimize the likelihood of emitter plugging.  
       [0005] An elastomeric valve has been developed to control flow rates in fluid distribution systems. This technology is demonstrated in U.S. Pat. Nos. 4,846,406, 4,869,432 and 4,909,441. A valve frequently made of an elastomeric material such as silicon rubber is designed to modulate fluid flow in response to variations in fluid pressure in the system pipeline. As system pressure increases, the elastomeric valve closes to reduce flow rate. Conversely, the valve opens in response to a reduction in system pressure. This latter tendency also makes these valves well suited for purging contaminates that might otherwise plug an exit orifice. While the elastomeric valve has been used in fluid distribution systems, such valves have not been integrated with the in-line type emitter. This is because in-line emitters and pressure compensating flow controls have conventionally been viewed as two very different systems. Flow controls with elastomeric pressure compensating valves typically incorporate the elastomeric valve in a position such that an entire in-line flow passes through the pressure compensating valve. Until now, no one has thought to combine the advantages of a pressure compensating valve with an in-line emitter in which the flow is a peripheral flow between the emitter and the tubing or pipe in which it is disposed.  
       SUMMARY OF THE INVENTION  
       [0006] The present invention provides an in-line fluid emitter facilitating a controlled flow of fluid from a pipe in which the emitter is disposed, comprising (1) a hollow generally cylindrical emitter body, with a plurality of openings defined in the emitter body to facilitate the flow of fluid therethrough; (2) a pressure compensating, resilient valve mounted in the emitter body; (3) a first passage defined in the emitter body directing the fluid from the openings to the valve; (4) an exit flow region defined in the emitter body, the exit flow region being in fluid connection with the output of the valve to receive fluid that has passed through the valve; and (5) a pair of annular sealing rings, one of which is disposed to a distal side of the openings, and the other of which is disposed to a distal side of the exit flow region, to seal the area between the pipe and the emitter.  
       [0007] Another aspect of the invention is a method for providing a flow of fluid from a pipe that compensates for variations in input pressure. The method includes the following steps: (1) providing a fluid emitter having a hollow, generally cylindrical emitter body, a plurality of openings defined in the emitter body to facilitate the flow of fluid therethrough, and an exit flow region; (2) positioning a pressure compensating, resilient valve in the emitter body, downstream of the openings and upstream of the exit flow region, and in fluid communication with both; and (3) creating an orifice in the pipe in fluid communication with the exit flow region to permit fluid to flow from the emitter out of the pipe.  
       [0008] Yet another aspect of the present invention is an in-line fluid emitter facilitating a controlled flow of fluid from a pipe in which the emitter is disposed. The emitter includes the following features: (1) a hollow generally cylindrical emitter body; (2) channels for directed fluid flow on the exterior surface of the body, hydraulically coupled with the hollow interior of the body; (3) a pressure compensating, resilient valve mounted to the emitter body such that fluid that passes through the channels flows through the valve; and (4) raised annular sealing rings positioned on the emitter disposed distally of the channels and valve such that they generally seal the area between the emitter and a pipe. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a schematic side elevation view of a pipe having a plurality of in-line emitters therein;  
     [0010]FIG. 2 is an isometric exploded view of one of the in-line emitters of FIG. 1;  
     [0011]FIG. 3 is another isometric view of one of the in-line emitters of FIG. 1;  
     [0012]FIG. 4 is yet another isometric view of one of the in-line emitters of FIG. 1;  
     [0013]FIG. 5 is a side elevation view of the embodiment of one of the in-line emitters of FIG. 1, showing the back side of the emitter;  
     [0014]FIG. 6 is an enlarged isometric view of the pressure compensating valve of one of the emitters of FIG. 1;  
     [0015]FIG. 7 is another enlarged isometric view of the pressure compensating valve of one of the emitters of FIG. 1;  
     [0016]FIG. 8 is an isometric view of one of the in-line emitters of FIG. 1, showing the pressure compensating valve and its housing in place in the emitter body; and  
     [0017]FIG. 9 is a side elevation sectional view of one of the emitter of FIG. 1, showing the flow of fluid through the valve. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0018] FIGS.  1 - 9  depict a preferred embodiment of the present invention. FIG. 1 is a schematic drawing illustrating a portion of a simplified fluid distribution system  10 . The system depicted includes plural in-line emitters  12  positioned within a pipe  14 , with orifices  16 . Pipe orifices  16  are disposed in axial alignment with exit flow regions  18  or  20  in emitters  12 . It can be seen that regions  18  and  20  are defined at their axially-outer or distal sides by annular sealing rings  22  and  24 , respectively. As will be explained more fully below, sealing rings  22  and  24  seal the area between emitter  12  and the inner surface of pipe  14 . Annular ridges  26  and  28  define the axially-inner sides of regions  18  and  20 , respectively. As will be explained in detail below and as depicted in FIGS.  2 - 5 , annular ridges  26  and  28  do not extend around the entire periphery of emitter  12  in order to facilitate flow of fluid into exit flow regions  18  and  20 . The gap(s) in annular ridges  26  and  28  have not been shown in FIG. 1 for simplification but will be shown and discussed below.  
     [0019] Emitter  12  is comprised of essentially three parts: an emitter body  30 ; a pressure compensating valve  32 ; and a valve housing  34 . As shown in the figures, valve  32  fits into housing  34 , which mounts to emitter body  30 . The construction of valve  32  and housing  34  and the relationship between these components will first be described before turning to the emitter body itself.  
     [0020] Pressure compensating valve  32  is best shown in FIGS. 6 and 7. The valve includes two components—a mounting shoulder  36  and a flapper valve  38 . Flapper valve  38  is comprised of two identical flap portions  38   a  and  38   b  formed to extend in a generally parallel fashion, close to each other. Flap portions  38   a  and  38   b  are formed of a resilient material, preferably silicon rubber. Each flap includes a semicylindrical groove  40   a  or  40   b , which combine to form a generally cylindrical channel  40  extending entirely through flapper valve  38 . As will be explained more fully below, the presence of channel  40  ensures a certain predetermined amount of flow through valve  32  even when flap portions  38   a  and  b  are closed tightly against one another.  
     [0021] Flap portions  38   a  and  b  of flapper valve  38  are mounted by adhesive or other permanent means to mounting shoulder  36 . Both mounting shoulder  36  and flapper valve  38  are designed to fit within a cylindrical space defined in valve housing  34 .  
     [0022] The cylindrical shape of mounting shoulder  36  has a diameter slightly greater than the side-to-side dimension of flapper valve  38 . Mounting shoulder  36  has an inner diameter  43  (see FIG. 6) that is somewhat larger than the diameter of flapper valve  38  when it is entirely open.  
     [0023]FIG. 9 shows valve  32  positioned within valve housing  34 . It can be seen that flapper valve  38  is positioned well inside of housing  34 . Precise positioning of valve  32  is possible because mounting shoulder  36  is fitted against a complementing wall  35  in housing  34 . Peripheral edge  44  includes a notch  46  at the upper or outer portion designed to complement a corresponding notch  48  in emitter body  30 , as shown best in FIG. 8. Complementing notches  46  and  48  are designed to facilitate flow of fluid into valve housing  34  and then through valve  32  as shown in FIG. 9 and as will be explained more fully as this discussion continues.  
     [0024] Valve housing  34  includes a pair of mounting wings  50   a  and  50   b  that fit into a corresponding pair of undercut portions  52   a  and  52   b  in emitter body  30 . The upper or exterior profile of wings  50   a  and  b  is rounded to conform to the inner diameter of pipe  14  within which emitter  12  is designed to fit. The remaining portion of valve housing  34  is also profiled to fit within the cylindrical inner diameter of pipe  14 .  
     [0025] The underside or inner side  54  of valve housing  34  is typically cylindrical, as is a complementing cylindrical space  42  of emitter body  30 . The end of valve housing  34  that is opposite from valve  32  is provided with a fluid exit notch  58  to permit fluid that has passed through valve  32  to exit the valve housing. Valve housing  34  with valve  32  mounted therein can typically merely be press-fit into the complementing cylindrical space  42  in emitter body  30 , although in certain applications it may be desirable to actually snap the housing in place, using one or more detent ridges (not shown). The remaining portion of emitter body  30  will now be described. The order that this description will follow will conform to the passage of fluid through the system  10 . As noted previously, in-line emitter  12  is positioned within pipe  14 . The fit is tight, so that annular sealing rings  22  and  24  fit tightly against the inner diameter of pipe  14 . As depicted, annular sealing ring  22  is disposed distally of exit flow region  18  while annular sealing ring  24  is disposed distally of openings  60  to be described below. Annular sealing rings  22  and  24  are actually made up of separate rings  22   a, b  and  c  and  24   a, b  and  c . This provides three separate seals that best insures that there will be minimal leakage across the seal.  
     [0026] The inner periphery of emitter body  30  is typically smooth, to minimize any disruption and flow of fluid through pipe  14 . That fluid which does pass through emitter  12  first passes through openings  60  in emitter body  30 . There are normally several hundred such openings, although the number and size of such openings may be varied depending on the particular application. A typical size would be approximately {fraction (1/64)} of an inch square. Another way to describe these openings is that collectively they define a screen. As shown in the figures, these openings  60  cover much of the surface of emitter body  30 , although in the preferred embodiment the openings are in two arrays, offset 180° from each other. One such array is shown in FIGS.  2 - 4  and the other is shown in FIG. 5. A plurality of circumferentially extending support ridges  62  extend between openings  60  to support pipe  14  and maintain the spacing between the inner diameter of pipe  14  and an outer surface area  64  of emitter body  30 . The fluid that has flowed through openings  60  is prevented from passing directly into exit flow region  20  by annular ridge  28 . Therefore, the only place for the fluid to go is to pass through pressure compensating valve  32 .  
     [0027] Depending upon the fluid pressure, flap portions  38   a  and  b  of flapper valve  38  will be in their closed position with the flap portions  38   a  and  b  tight against each other to minimize flow during periods of high inlet pressure, or in a full open position in which flap portions  38   a  and  b  yawn open to maximize flow during periods of low pressure, or any position therebetween. An intermediate position is shown in FIGS. 6 and 7. In their closed position, the only opening in valve  32  is defined by a central channel  40  extending through flapper  38 . This ensures that even when the valve is closed, there will be some flow of fluid through the valve. Because the opening in valve  32  is small when pressure is at its highest, this will even-out the ultimate flow from the emitter during periods of peak pressure. When lower pressure is present, there will be less pressure on flap portions  38   a  and  b , so the flaps will take a more open position. During these periods of low pressure, flow will be maximized to again even-out the flow regardless of the inlet pressure. Once fluid passes through flapper valve  38  and the interior of valve housing  34 , it passes out fluid exit notch  58  and through the rear of the housing to enter valve exit region  68  where the fluid is directed through gaps  70  and into exit flow region  18 . Fluid then can pass through orifice  16  for irrigation or leaching purposes.  
     [0028] Adjacent to pressure compensating valve  32  and valve housing  34  is a pipe-supporting surface  72  which, like supporting ridges  62 , supports pipe  14 . It has been determined that the presence of this supporting surface  72  in combination with annular sealing rings  22  and  24 , as well as support ridges  62 , provides sufficient support that pipe  14  is unlikely to collapse even when confronted with substantial exterior loads such as may be encountered when pipe  14  is buried under several feet of minerals being leached.  
     [0029] System  10  is used in many applications where clogging of orifices  16  may be possible. This problem is particularly acute in mining operations. In the event that any of orifices  16  become clogged, one advantage of the system is that a second orifice may be formed in pipe  14 , but instead of being positioned in exit flow region  18 , it may be bored into pipe  14  at exit flow region  20 . Thus, if orifice  16  and its adjacent flow region  18  is clogged with particulate, fluid may pass through the region indicated at  74  in FIGS. 3 and 8 and thus access exit flow region  20 . Given the configuration of region  74 , there will be little pressure drop as fluid passes the length of emitter  12  and then out the new orifice. A plurality of support ridges  76  are provided in region  74  to support pipe  14  away from emitter body surface area  64 . This ability of being able to bore or cut a second hole in emitter  12  means that this emitter can be kept functional without having to cut the pipe to remove a clogged emitter, and replace it with another.  
     [0030] Variation in the configuration of flapper valve  38  permits a 5-fold increase in the size of the emission path diameter. It has been found that a relatively constant discharge rate can be achieved through a range of input pressure between 10 and 60 psi. The depicted embodiment also facilitates a purging cycle which can be used to purge emitter  12  and its pressure compensating valve  32 . An additional advantage of system  10  is that different pressure compensating valves  32  may be substituted one for the other, to provide an emitter which will have a greater or lesser flow rate. Valves having flow rates of ½, ¾, 2 and 3 gph are typically provided. Alternative pressure compensating valves may be color coded to show differences in flow rate.  
     [0031] These and other variations and modifications to the preferred embodiment may be made without departing from the spirit and scope of the present invention. These and other modifications within the scope of this disclosure are intended to be covered by the claims which follow.