Patent Publication Number: US-2013228636-A1

Title: Pressure compensating nozzle improvements

Description:
This invention relates to a means of compensating for pressure variations in water supply to irrigation devices, such as sprinklers. 
     PRIORITY 
     This patent application claims priority from: 
     Australian Provisional Patent Application 2010902433, titled “PRESSURE COMPENSATING NOZZLE IMPROVEMENTS”, and filed on 3 Jun. 2010. 
     The entire contents of this application are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     Pressure compensators in irrigation equipment ensure that each sprinkler discharges at substantially the same volume flow rate. Supply pressure along a distribution line can vary considerably due to friction losses, resulting in a significantly lower pressure at the end of a long run. In addition, irrigation lines installed on a slope with a significant height variation from one end to the other will also suffer considerable pressure variations along the line. This would result in some areas of a crop receiving more water than others unless some form of pressure compensation is used. 
     The applicant previously devised a pressure compensator for an irrigation sprinkler that addressed at least some of the above stated problems. This pressure compensator is as disclosed in U.S. Pat. No. 6,145,760, the entire contents of which should be considered incorporated herein by way of reference. 
     The use of elastomeric discs in such pressure compensators is disclosed in U.S. Pat. No. 6,145,760. These elastomeric discs are positioned over apertures and the flow rate of water past the disc is regulated by the flexing of the disc over a flow path. Generally, the disc is positioned over a recess and has a water passageway which is progressively reduced in area as the disc flexes further into the recess. 
     A problem with existing pressure compensators is blockage and the difficulty in removing blockages. When the water supply is turned off, the elastomeric disc flattens so that the initial water flow, when next turned on, will flush away any blockages. However, the channels are often very small and therefore do not flush adequately. 
     Also, the use of such small channels requires a great degree of accuracy in manufacture to ensure consistent flow control. 
     It is an object of the present invention therefore to provide a pressure compensator of improved performance in one or more of the above described respects, or which at the least provides a useful alternative to known pressure compensators for irrigation sprinklers. 
     Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. 
     SUMMARY OF THE INVENTION 
     In one aspect of this invention there is proposed a pressure compensator for use with an irrigation device, the pressure compensator comprising:
         a body defining a fluid passageway for fluid flow;   an elastomeric membrane;   a substantially concave seating surface substantially covered by the membrane, said seating surface having a peripheral edge against which said membrane locates,   wherein the seating surface and the elastomeric membrane seated thereby are positioned in the path of fluid flow so as to be either parallel with or inclined at an angle relative to the fluid flow.       

     In one form, the body comprises a nozzle, and the seating surface and the elastomeric membrane seated thereby are upstream of, and either parallel with or inclined at an angle relative to a direction of elongation of the nozzle. 
     In one form, the fluid passageway and the direction of elongation of the nozzle are substantially aligned, and the seating surface and the elastomeric membrane seated thereby are inclined at an angle relative to the direction of elongation of the nozzle. 
     In one form, the membrane is a disc. 
     In one form, by virtue of being parallel to or inclined at an angle relative to the fluid flow direction, the seating surface has an upstream peripheral edge, and a downstream peripheral edge. 
     In one form, there is at least one recess portion on the upstream peripheral edge of said seating surface that defines an aperture between the disc and the seating surface when no force is applied to the disc, and which provides flow control as the contacting face of the disc flexes into the recess when force is applied to the disc. 
     In one form, the or each recess partly extends into the seating surface so that the flow past the or each recess is prevented by sufficient flexing of the disc into the seating surface. 
     In one form, one or more channels extend from the upstream peripheral edge to or near an aperture in the seating surface, each channel defining an aperture between the disc and the seating surface when no force is applied to the disc. 
     Rather than using one or more very fine or small width channels, it has been found that the use of a wider and deeper channel of greater length need not impair flow control. The advantages of a larger channel include: 1. a larger channel is less likely to block; 2. any blockage will clear more readily; and 3. a larger channel is easier to make due to being less sensitive to dimensional variation. 
     In one form, the body comprises a nozzle extending in the direction of fluid flow, so that the seating surface and the elastomeric disc seated thereby are either parallel with or inclined at an angle relative to a direction of elongation of the nozzle. 
     In one form, the aperture in the seating surface is an inlet to the nozzle. 
     In one form, the body comprises a fluid inlet within which the pressure compensator locates. In an alternative, the pressure compensator is located between a fluid inlet and fluid outlet for the body. 
     In one form, the body comprises one or more notches that partly extend into said seating surface, each notch defines an aperture between the disc and the seating surface when no force is applied to the disc. 
     These notches provide a further degree of flow control as the elastomeric disc flexes into the recesses. More particularly, these notches provide further flow control during initial stages of flexing of the disc. Further flexure will then cause the notches to be closed off which will then prevent flow past this portion of the elastomeric disc. Once this occurs, then other flow control arrangements such as the channels are relied upon. 
     In one form, the disc is circular and the seating surface is circular. 
     The elastomeric disc may be used in any number of different shapes. In one form, the disc is circular, but a square or elliptical shape may also be used and should be considered included within the meaning of the term “disc”. 
     In a further aspect, the invention may be said to reside in a pressure compensator for use with an irrigation device comprising: 
     a body defining a fluid passageway, fluid flow direction, and a nozzle extending in the direction of fluid flow;
         an elastomeric membrane;   a substantially concave seating surface which is covered by said membrane, said seating surface having a peripheral edge against which said membrane locates,   wherein the seating surface and the elastomeric membrane seated thereby are positioned in the fluid flow and either parallel with or inclined at an angle relative to a direction of elongation of the nozzle.       

     In a further aspect, the invention may be said to reside in an irrigation device incorporating the above described pressure compensator. 
     In a further aspect, the invention may be said to reside in a means of compensating for pressure variations in water supply to irrigation sprinklers, the means comprising 
     a body defining a fluid passageway and fluid flow direction,
         an elastomeric membrane,   a substantially concave seating surface which is covered by said membrane, said seating surface having a peripheral edge against which said membrane locates,   wherein the seating surface and the elastomeric membrane seated thereby are positioned in the fluid flow and either parallel with or inclined at an angle relative to the fluid flow direction.       

    
    
     
       DESCRIPTION OF THE DRAWINGS 
       For a better understanding of this invention it will now be described with respect to an exemplary embodiment which shall be described herein with the assistance of drawings wherein: 
         FIGS. 1 and 2  are perspective views of a sprinkler incorporating a pressure compensator according to an exemplary embodiment; 
         FIG. 3  is a perspective view of the pressure compensator in isolation, where the elastomeric disc has been removed to permit visibility of body details; 
         FIG. 4  is a view of the pressure compensator body in  FIG. 3 , viewed from the end that seats the elastomeric disc; 
         FIG. 5  is front view of the pressure compensator inclusive of the elastomeric disc; 
         FIG. 6  is a cross-section view through the body taken along line A-A of  FIG. 5 ; and 
         FIG. 7  is front view of the pressure compensator that is similar to  FIG. 5 , but including detail of hidden features. 
     
    
    
     In the following description, like reference characters designate like or corresponding parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 and 2  illustrate perspective views of an irrigation device comprising a pressure compensating means, the irrigation device being a sprinkler  8 . The sprinkler  8  is typical of miniature sprinklers which distribute water via a rotor  9 . The sprinkler has a fluid inlet  10  in an underside thereof within which a pressure compensator  11  locates, although the pressure compensator  11  is not limited to use in sprinklers of this type. 
     With reference to  FIGS. 5 through 7 , it can be seen that the pressure compensator  11  comprises two components. The first is a moulded body  12  defining a fluid passageway and fluid flow direction, and which includes a seating surface  13  that is inclined at an angle relative to the fluid flow direction through the fluid passageway. An elastomeric disc  15  is positioned over the seating surface  13 , and is held in place by protrusions  16  on posts  17 . 
     The seating surface  13  and the elastomeric membrane (a disc in this case)  15  seated thereby are inclined at an angle between 0 degrees, or parallel to the direction of fluid flow, and less than 90 degrees, or less than normal to the direction of fluid flow. In the illustrated embodiment this angle is approximately 30 degrees to the fluid flow direction, although this angle may be varied depending on the fluid flow conditions required. 
     As can be seen in  FIGS. 3 and 4 , an aperture  19  is formed near the centre of the seating surface  13  and allows water flow through to a convergent nozzle  20  downstream of the seating surface  13  that produces a jet of water that impacts against rotor  9  so as to be redirected radially. 
     The elastomeric disc  15  locates over seating surface  13 , the seating surface  13  comprising a concave recess formed by a conical wall  21  and a peripheral edge  22 . 
     Because the seating surface  13  is inclined at an angle relative to the fluid flow direction, this has an upstream peripheral edge  22   a,  and a downstream peripheral edge  22   b.  Similarly, the elastomeric disc  15  has an upstream peripheral edge  15   a,  and a downstream peripheral edge  15   b.    
     As can be seen in  FIG. 6 , the downstream peripheral edge  15   b  of the elastomeric disc  15  is located in a slot located between the downstream peripheral edge  22   b  of edge  22  and the outer wall  12   a  of the body  12 , and the upstream peripheral edge  15   a  of the elastomeric disc  15  is retained by the protrusions  16  on posts  17 . In this way, the elastomeric disc  15  is securely seated on seating surface  13 . 
     Two channels  25  (although in some cases only one may suffice, or three or more may be required) extend from the upstream peripheral edge  22   a  to the aperture  19 . It is primarily through these channels which the metered water supply flows to the nozzle  20 , where aperture  19  is, is in the illustrated embodiment, the inlet to the nozzle  20 , and the channels  25  also break through a wall of the nozzle  20 . 
     As the supply pressure of the fluid increases, the disc  15  flexes into the conical recess of the seating surface  13 . As the disc  15  seals against the conical wall  21 , ingress for water is limited so as to be mainly via the channels  25 . Accordingly, the degree of flexion of the disc  15  determines the extent of contact of the disc  15  along the channels  25  and therefore the effective area and length through which fluid can flow. Obviously, maximum deflection of the disc  15  will result in minimum aperture and channel size and flow along the channels  25 , and therefore the greatest restriction to flow. 
     As can be seen in at least  FIGS. 3 and 4 , there is, in the illustrated embodiment, a notch  28  that extends a short distance into the seating surface  13  located on either side of the two channels  25 . Notches  28  may be omitted or vary in number depending upon the desired flow characteristics. When the disc  15  is deformed so that it is in contact with the edge  22   b  flow will still occur via the notches  28 . Further flexing of the disc  15  into the seating surface  13  will eventually cause the notches  28  to be closed so that the only means of flow control reverts to the channels  25 . At this stage, the pressure will obviously be sufficient to force the concave deformation of the disc  15  so that flow control will only be by the channels  25 . 
     The elastomeric disc  15  operates in the above described manner only once the fluid supply pressure reaches a certain pressure. Below this pressure, there is very little flexion of the disc  15 , which in turn results in no pressure compensation below this given pressure. 
     As is discussed in U.S. Pat. No. 6,145,760, the upstream peripheral edge  22   a  and a portion of the conical wall  21  may, in conjunction with of channels  25  and/or notches  28 , be provided with a recess (see item  26  of U.S. Pat. No. 6,145,760) which creates an aperture in the side of the seating surface  13  when no force is applied to the, disc  15 . Instead of the disc  15  having to deform into the concave seating surface  13  to commence flow control, the edge of the disc  15  can deform into the recess  26 . This deformation requires much less force, and therefore will provide a degree of flow control at lower pressures. 
     Any blockage pressure compensator  11  caused by build-up of debris will be flushed when fluid next flows through the sprinkler  8 . If the pressure compensator  11  blocks through debris lodging in channels  25  or notches  28 , the initial flow of water will have such energy as to stand a good chance of clearing the blocking material. The large area between the disc  15  and the edge  22   b  allows a forceful initial flow of water through the channel  25 , and thereby aids in the clearance of any blockage. This flushing flow will continue until the disc  15  starts to deform. 
     The use of a large channel  25  also means that manufacturing tolerances do not need to be so fine. 
     Where fluid flow incident to the pressure compensator of U.S. Pat. No. 6,145,760 strikes the elastomeric disc of this at an angle normal to the disc resulting in break up of the stream and loss of stream energy, the fluid flow incident to the pressure compensator according to the present invention strikes an upstream edge  22   a  of the elastomeric disc  22 . 
     As will be seen from the above description, the invention provides reduced disturbance to fluid flow through the pressure compensator  11 , which results in less break up of the stream, meaning a more cohesive stream possessing greater energy and, as a result, increased sprinkler  8  throw (radius) and therefore wetted area for a given fluid supply rate. Moreover, because fluid flow is more directly directed to the aperture  19  and in turn the nozzle  20 , nozzle  20  can be narrower at its inlet (aperture  19 ) and therefore of a design (such as a more slender design) that will release fluid with a greater outlet velocity, where this too will contribute to the improved throw and wetted area. 
     It is further anticipated that the design also provides improved flushing to clear blockages, as again, the stream has increased energy for clearing blockages. 
     The pressure compensating device  11  as described above will be capable of being used in a number of irrigation devices such as drip emitters or rotating nozzle-style sprinklers. The basic operating principle will remain the same regardless of the irrigation device used. Moreover, the number and configuration of any of the channels  25 , recesses  26  and notches  28  may be varied along with characteristics of the elastomeric disc  15  so that there is a pressure compensator for almost every application. 
     It will be understood that the term “comprise” and any of its derivatives (e.g. comprises, comprising) as used in this specification is to be taken to be inclusive of features to which it refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied. 
     Any and all publications mentioned in this specification are herein incorporated by reference. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of each claim of this application. 
     Although the disclosure has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised that departures can be made within the scope of the invention, which is not to be limited to the details described herein but is to be accorded the full scope of the appended claims so as to embrace any and all equivalent devices and apparatus.