Abstract:
A pulsating irrigation device is provided that transforms a fluid flow entering the device to an intermittent pulsating fluid flow that is ejected from the device. The device has a chamber and at least one compressible member in pressure contact with the chamber. The compressible member compresses to assist the formation of the pulses ejected from the device and the fluid within the chamber is substantially sealed from contact with the interior of the compressible member.

Description:
RELATED APPLICATIONS 
       [0001]    This is a Continuation of PCT/IL2011/000201, which was filed 1 Mar. 2011 and published as WO 2011/1110371A1 on 15 Sep. 2011, and which claims priority to U.S. Provisional Patent Application No. 61/311,334, filed 7 Mar. 2010. The contents of the above-identified applications are incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments of the present invention relate to pulsating irrigation devices and in particular to pulsating devices that transform an incoming fluid flow to an intermittent pulsating ejected fluid flow. 
       BACKGROUND 
       [0003]    In such devices, the incoming fluid flow may be of relatively low flow and the ejected pulses may be transformed to be of a relatively high flow. 
         [0004]    U.S. Pat. No. 5,727,733 describes a pulsating device with an elastic tube that can expand and contract on a barbed insert. Fluid entering the device fills a space between the elastic tube and the insert thereby increasing its volume until forming an opening between the tube and a barb of the insert that allows fluid to flow out from the space and onwards until it is finally ejected from the device as a fluid pulse. 
       SUMMARY 
       [0005]    The following embodiment and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. 
         [0006]    In an embodiment of the present invention there is provided a pulsating device for transforming a fluid flow entering the device from a fluid source upstream to an intermittent pulsating fluid flow ejected from the device downstream, the device comprising a chamber for receiving the fluid flow entering the device from the fluid source and at least one compressible member in pressure contact with the chamber for assisting the formation of the pulsating fluid flow ejected from the device, wherein the fluid flow received within the chamber is substantially sealed from communication with an interior of the compressible member. 
         [0007]    Optionally, the fluid entering the chamber increases the pressure within the chamber and the device further comprises a valve that is adapted to open above a first threshold pressure Po within the chamber to allow a fluid pulse to exit the chamber and after being opened to close below a second threshold pressure Pc within the chamber to terminate the fluid pulse exiting the chamber. 
         [0008]    If desired, the compressible member is located within the chamber. 
         [0009]    Optionally, the interior of the compressible member comprises a compressible material. 
         [0010]    If desired, the compressible material is fluid. 
         [0011]    Optionally, the fluid is gas or air. 
         [0012]    Typically, the interior of the compressible fluid has a pressure Pg when no external pressure is applied thereupon, and wherein Pg&lt;Po and optionally Pg&lt;Pc. 
         [0013]    Further typically, the first threshold pressure Po is larger than the second threshold pressure Pc. 
         [0014]    Optionally, the fluid has a pressure Ps at the fluid source and the device comprises a flow control means via which the fluid entering the chamber from the fluid source passes, the flow control means forming a pressure drop Pd to the fluid entering the chamber, wherein Ps−Po≧Pd. 
         [0015]    If desired, the fluid entering the chamber has a flow rate Fin and the flow rate of fluid exiting the chamber just before the second threshold pressure Pc in the chamber is reached and the valve closes is Ft, wherein Fin&lt;Ft. 
         [0016]    In addition to the exemplary aspects and embodiment described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0017]    Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative, rather than restrictive. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying figures, in which: 
           [0018]      FIG. 1  schematically shows a side view of a pulsating device in accordance with an embodiment of the present invention; and 
           [0019]      FIGS. 2 to 5  schematically show partial cross sectional views of the pulsating device of  FIG. 1  at various stages of its pulsating operation. 
       
    
    
       [0020]    It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated within the figures to indicate like elements. 
       DETAILED DESCRIPTION 
       [0021]    Attention is first drawn to  FIG. 1 . A pulsating device  10  in accordance with embodiments of the present invention is adapted to transform an incoming fluid flow from a fluid source  12  upstream to an outgoing fluid pulse that is ejected downstream. The fluid may be a liquid such as water that may contain substances used in agricultural applications in which the device may be utilized such as plant nutrients, pesticides and/or medications; and the fluid source upstream may optionally be a pipe such as an irrigation pipe and the ejected fluid pulse flowing downstream may optionally be emitted to the outside environment by an emitter  14 . 
         [0022]    It is noted that the ejected fluid flow exiting the device may in some embodiments be of a non-regulated nature, and in other embodiments may be of a regulated nature that exhibits a substantially constant emitted fluid flow or pulse for a given pressure range for which it is designed to operate. This non-regulated or regulated nature may be defined for example by the emitter  14  being used if it is respectively of the non-regulated type or of the regulated type. In addition, the device  10  in accordance with various embodiments may be used in agricultural and non-agricultural applications such as irrigation, frost protection, cooling in dwellings such as greenhouses (etc.). It should be noted that directional terms appearing throughout the specification and claims, e.g. “upstream”, “downstream” etc., (and derivatives thereof) are for illustrative purposes only, and are not intended to limit the scope of the appended claims. 
         [0023]    Attention is additionally drawn to  FIG. 2 . In an embodiment, the pulsating device  10  has a chamber  16 , at least one compressible member  18  located optionally in the chamber  16 , a flow control means  20  located upstream of the chamber, and a valve  22  located downstream of the chamber  16 . The compressible member  18  has an optional outer boundary  24  that optionally encapsulates an interior  26  thereof which in an initial non-compressed state of the compressible member  18  has an initial volume  261 . Upon commencement and then rise of external pressure within the chamber  16  that is applied thereupon, the compressible member  18  is adapted to be squeezed to have a reduced interior volume that is smaller than the initial volume  261  and upon the reduction of such external pressure the compressible member  18  is adapted to expand back towards its initial volume  261 . 
         [0024]    The valve  22  may be adapted to open and allow fluid to flow downstream out of the chamber  16  above a first threshold pressure Po in the chamber  16  and after being opened may shut off to close the path out of the chamber  16  as the pressure within the chamber  16  drops to a level below a second threshold fluid pressure Pc which is smaller than the first threshold pressure Po. 
         [0025]    Attention is additionally drawn to  FIG. 3 . In an embodiment, fluid having a pressure Ps at the fluid source  12  that enters the device  10  flows through the flow control means  20  where it is urged to pass via a limited passage that reduces the flow rate of fluid entering the chamber  16  to a relatively low incoming fluid rate Fin. The chamber  16  receiving the fluid from the fluid source  12  may in some cases include air such as when first starting to use the device  10  or may be substantially full of fluid such as fluid that it optionally already received from the fluid source  12 . Such air that may be present in the chamber  16  may exit the chamber  16  for example via the emitter  14  during use of the device  10  or may remain at least partially trapped within the chamber  16 . The fluid being received in the chamber  16  increases the pressure in the chamber  16  and occupies at least a part of the volume initially occupied by the compressible member  18  by squeezing the compressible member  18  away from its initial volume  261  which is outlined in  FIG. 3  by a dashed line towards a squeezed terminal state where it has a reduced terminal volume  262 . The reduced terminal volume  262  is outlined in  FIG. 3  by a continuous line and is associated with a rise of pressure within the chamber  16  to the first threshold pressure Po. 
         [0026]    The fluid passing through the limited passage in the flow control means  20  exhibits a pressure drop Pd; and Ps, Pd and Po should satisfy a relationship of Ps−Po≧Pd for the valve  22  to be able to open and allow fluid out of the chamber  16 . Optionally, the flow control means  20  is of a regulating type such as a regulating drip emitter that is adapted to regulate the flow rate of fluid entering the chamber  16  to a nominal substantially constant incoming fluid rate Fin that is substantially independent of inlet pressure Ps at the fluid source  12  for a given pressure range for which it is designed to operate. The pressure range Pmin to Pmax defines the given range for which the regulating flow control means  20  is designed to regulate; and Pmin, Pmax and Pd should satisfy the relation of Pmax≧Pd≧Pmin for the incoming fluid rate Fin to be regulated. 
         [0027]    Attention is additionally drawn to  FIG. 4 . As the pressure within the chamber  16  rises and reaches the first threshold pressure Po, the valve  22  opens and a path is formed via which a given fluid pulse indicated in  FIG. 4  by arrows  28  may start to form. The pulse flows downstream out of the chamber  16  optionally to the emitter  14  where it may be ejected out to the external environment. As the pulse exits the chamber  16 , the pressure within the chamber  16  drops and the compressible member  18  expands back towards its initial volume  261  to assist the formation of the pulse being ejected out of the device  10  by recapturing a partial-volume in the chamber  16  that was previously occupied by fluid thereby urging an amount of fluid in the chamber  16  substantially equal to said partial-volume out of the chamber  16 . Both the initial and terminal volumes  261 ,  262  of the compressible member  18  are outlined in  FIG. 4  by dashed lines while the compressible member  18  on its expansion from the terminal volume  262  towards the initial volume  261  is outlined in  FIG. 4  by a continuous line. 
         [0028]    Attention is additionally drawn to  FIG. 5 . As the level of pressure within the chamber  16  decreases towards the second threshold pressure Pc, the flow rate of fluid exiting the chamber  16  may decrease too if being of the non-regulated nature towards a terminal fluid rate Ft that is present just before the pressure in the chamber  16  reaches the second threshold pressure Pc and the valve  22  closes to terminate the given fluid pulse being ejected out of the device  10 . The flow rate of fluid exiting the chamber  16  if being of the regulated nature may be substantially equal to Ft for a given pressure range for which it is designed to be regulated. The closing valve  22  stops the expansion of the compressible member  18  at an inflated volume that optionally may be similar to or smaller than the initial volume  261 . The ongoing incoming fluid rate Fin entering the chamber  16  at the flow control means  20  resumes to increase the pressure in the chamber  16  which leads to the formation of a consecutive fluid pulse that is ejected from the device  10 . The initial and terminal volumes  261 ,  262  of the compressible member  18  are outlined in  FIG. 5  by dashed lines and the inflated volume of the compressible member  18  is outlined in  FIG. 5  by a continuous line. In an embodiment, the terminal fluid rate Ft and the incoming fluid rate Fin satisfy a relationship of Fin&lt;Ft for the valve  22  to be able to close the exit of fluid out of the chamber  16  as the pressure in the chamber  16  drops to the second threshold pressure Pc. 
         [0029]    In an embodiment, the interior  26  of the compressible member  18  may consist of various types of compressible materials such as gas or air and the outer boundary  24  of the compressible member  18  may be substantially impervious so as to substantially seal the interior  26  of the compressible member  18  from contact with fluid in the chamber  16 . In the optional case where the compressible material is any fluid such as gas or air, such fluid has a pressure Pg that is measured when no external pressure is applied thereupon. In embodiments of the present invention, Pg satisfies a relationship of Pg&lt;Po so that the compressible member  18  may exhibit compression during use of the device  10 , and preferably Pg satisfies a relationship of 0≦Pg≦Pc so that the compressible member  18  may immediately start to compress as pressure in the chamber rises to above the second threshold pressure Pc. 
         [0030]    The outer boundary  24  of the compressible member  18  may optionally be formed from materials that increase the barrier properties of the outer boundary  24  such as polymers like Polyvinylidene Chloride or copolymers like EVOH or metalized laminate films like the Metalized laminate polyester film manufactured by Shanghai Radix Vacuum Metallising Co. Ltd. or the VIP laminate film manufactured by Hanita Coatings RCA Ltd. 
         [0031]    By way of a non binding example, a pulsating device  10  in accordance with an embodiment of the present invention may communicate with a fluid source upstream having a pressure Ps of 2.5 to 5 bars, the valve  22  may have a first threshold pressures Po of 2 bars and a second threshold pressure Pc of 1 bar, the flow control means  20  when being of the regulated type may create a pressure drop of between 0.5 to 4 bars at the fluid passing therethrough and the incoming fluid rate Fin formed by such a regulated flow control means  20  may be 12 L/h and the fluid rate exiting the chamber  16  just before the valve  22  closes may have terminal fluid rate Ft of 20 L/h. 
         [0032]    In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. 
         [0033]    Although the present embodiment has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the scope of the invention as hereinafter claimed.