Abstract:
A method of operating an irrigation system includes providing a flow of irrigation water, forming a flow of filtered water by removing particulate matter from the flow of irrigation water by using a filter, and directing a first portion of the flow of filtered water to a control valve. The method also includes directing a second portion of the flow of filtered water to a pressure regulator, delivering a flow of water from the pressure regulator to one or more irrigation devices, and automatically cleaning the surface of a filter upon activation or deactivation of the irrigation system.

Description:
CROSS-REFERENCE To RELATED APPLICATION 
       [0001]    This application is a divisional of prior application Ser. No. 11/205,524, filed Aug. 17, 2005, co-pending, which is a continuation-in-part of prior application Ser. No. 11/088,486, filed Mar. 24, 2005, abandoned, which claims benefit of U.S. Provisional Application Number 60/557,444, filed Mar. 29, 2004, which are hereby incorporated herein by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present invention generally relates to control devices for use with irrigation systems and, more particularly, to a pressure regulator and filter for an irrigation system. 
       BACKGROUND 
       [0003]    Irrigation systems are used to provide water to a wide variety of devices, including, for example, spray nozzles, sprinkler heads, and drip hoses. Such systems generally make use of control valves to command the flow of water through the system, pressure regulators to even out variations in source water pressure, and filters to remove debris and particulate matter from the water flow. 
         [0004]    Solenoid controlled on/off valves for use in irrigation systems are well known. For example, a solenoid-actuated valve uses a solenoid to command a small flow of control water, which, in turn, controls a larger flow of water to attached irrigation devices. Such solenoid-actuated valves often include relatively small passageways for the flow of control water and require the filtering of the control water to insure the removal of particulate matter which could block flow through the relatively small passageways. A filter may be placed upstream to filter the control water stream. 
         [0005]    Water filters are also used in a wide range of applications to remove particulate matter from an irrigation water flow stream. Irrigation water supplies may contain fine particulate matter and debris capable of obstructing flow through sprinkler heads or low-flow emitter devices such as drip hoses. Thus, it is necessary to filter the irrigation water supply upstream of attached irrigation devices. 
         [0006]    The aggregation of material on the upstream side of a filter can lead to a pressure drop across the filter medium and can significantly reduce water flow through the filter and adversely impact the performance of the irrigation system. Thus, it is also beneficial to be able to clean the filter medium. One known device uses scraper blades to clean the upstream surface of a filter each time the solenoid-actuated valve is opened or closed. Another known device is a self-cleaning filter device which is placed downstream from a control valve. This device filters the irrigation water stream and automatically cleans and back washes a filter on each on and off cycle of an upstream control valve. 
         [0007]    Prior irrigation devices provide filters for the irrigation water or for the control water, but not both. Irrigation control devices and filters are generally located in the field, and it can be inconvenient and costly to manually clean the filters and purge them of debris and other particulate matter. Thus, there is a need for an improved self-cleaning filter assembly which cleans a filter on each on and off cycle of a control valve and which filters both the control water for use by a control valve and the irrigation water for use by the irrigation system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional view of a self-cleaning filter, a pressure regulator, and a solenoid-actuated valve embodying features of the present inventions; 
           [0009]      FIG. 2  is a cross-sectional view of the self-cleaning filter assembly of  FIG. 1  in the flow on condition; and 
           [0010]      FIG. 3  is a cross-sectional view of the pressure regulator assembly of  FIG. 1  in the flow on condition. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    With reference to  FIG. 1 , there is illustrated a solenoid-actuated valve  2 , a pressure regulating valve  4 , and a self-cleaning filter assembly  6 , as an exemplary embodiment employing features in accordance with the present invention. These components are used to control fluid flow, such as water to an irrigation system. The solenoid-actuated valve  2  turns the flow in the irrigation system on or off by controlling a flow valve  8  in the pressure regulating valve  4 . The pressure regulating valve  4  maintains water pressure stability between an inlet  10  and an outlet  12  of the valve  4 . A self-cleaning filter assembly  6  is located upstream of both the solenoid-actuated valve  2  and the pressure regulating valve  4 . Thus, water flow to both the solenoid-actuated valve  2  and the pressure regulating valve  4  is filtered to remove foreign matter that may otherwise interfere with the operation of the solenoid-actuated valve  2 , the pressure regulating valve  4  or the irrigation system downstream. Although  FIG. 1  illustrates the combination of the self-cleaning filter assembly  6  and the pressure regulating valve  4 , other exemplary embodiments may use these components independently and still employ aspects in accordance with the present invention. In one form, the pressure regulator  4 , the filter assembly  6 , and the valve or control device  2  are incorporated into a single housing  7 . 
         [0012]    The solenoid-actuated valve  2  is used to control the flow between its on and off state of the irrigation system. The solenoid-actuated valve  2  is located downstream of the filter assembly  6 . A portion of the flow of filtered water from the filter assembly outlet  14  is directed to a flow restrictor  16 . The flow restrictor  16  limits the flow of filtered water to a very low rate, for example, less than ten gallons/hour. The output of the flow restrictor is directed to a T-connection  18  from which it can flow through passage  20  to the solenoid-actuated valve inlet  2   a  or through passage  22  to a two-way port  162  of a lockout chamber  26  of the pressure regulating valve  4 . 
         [0013]    The solenoid-actuated valve  2  includes a plunger valve  170  and a valve seat  172 . In the flow “off” condition, the solenoid  30  is de-energized, and a spring  174  biases the plunger valve  170  into engagement with the valve seat  172  to shut off flow through the solenoid-actuated valve  2  between the inlet  2   a  and the outlet  24 . This causes all of the water flowing from the restrictor  16  to flow into the lockout chamber  26 . The flow into the lockout chamber  26  causes it to become pressurized, which forces a lockout piston shaft  28  in the chamber  26  to move downward to close the flow valve  8 . 
         [0014]    In the flow “on” condition, the solenoid  30  is energized to retract the plunger valve  170  and remove it from the valve seat  172  to open the solenoid-actuated valve  2 . This allows flow through the solenoid-actuated valve  2  to the outlet  24 . A portion of the flow from the solenoid-actuated valve outlet  24  is directed to a two-way port  32  of a control chamber  34  of the self-cleaning filter assembly  6 . That flow pressurizes the control chamber  34  and causes the wiper assembly  36  to move to its downward position as described below. The remainder of the flow from the solenoid-actuated valve outlet  24  is directed to the irrigation system via passage  38 . 
         [0015]    During the normal course of operation, the irrigation system will cycle between flow “off” and flow “on” conditions. The control chamber  34  in the self-cleaning filter assembly  6  acts to operate the wiper assembly  36  to scrape the surface of a filter screen  40 , in a manner described below, when the system transitions between the flow “off” and flow “on” conditions. When the irrigation system is switched on, a small flow of control water enters the control chamber  34  through the port  32 , pressurizing the chamber  34  and urging a shaft  42  and wiper assembly  36  to a downward position. This movement causes the wiper  44  to scrape accumulated particulate matter from the upstream surface of the filter screen  40 . When flow in the system is switched off, control water ceases to flow into the control chamber  34 , and so, the control chamber  34  becomes depressurized. This depressurization allows a spring  46  to urge the shaft  42  and wiper assembly  36  into an upward position. This movement causes the wiper  44  to scrape the upstream surface of the filter screen  40  in the opposite direction. 
         [0016]    With reference to  FIG. 2 , the filter assembly  6  has a drive cylinder  47 , a body  48  defining an inlet  50 , an outlet  14  and a fluid flow passage  52  extending between the inlet  50  and the outlet  14 , and an end cap  49 . An o-ring  79  provides a water-tight seal between the body  48  and the end cap  49 . The inlet  50  and outlet  14  are designed for connection to piping or other conduit, such as by threads  54  and  56 , respectively, or by friction engagements. The fluid flow passage  52  allows water to flow through the filter assembly  6 . The filter screen  40  is located in the passage  52  to filter water that flows through the passage  52 . The drive cylinder  47  also defines the cylindrical control chamber  34  having the two-way port  32 . The port  32  is adapted for connection to a source of control water using threads  58 , as shown, or a friction connection. An exit port  60  in the filter assembly end cap  49  allows filtered particulate matter to be discharged from the filter assembly  6  as described below. 
         [0017]    The filter screen  40  preferably is comprised of a plastic or metallic material that defines a mesh of openings  62 . Although the filter screen  40  may take on many different configurations and shapes, the preferred filter screen has a hollow, generally cylindrical shape. The filter screen  40  includes a lower end support  64  and an upper end support  66  to aid in maintaining the shape of the filter screen  40  and to aid in mounting the filter screen  40  in the filter assembly body  48 . The lower end support  64  and the upper end support  66  are preferably comprised of plastic or metallic material. 
         [0018]    End cap  49  is suitably attached and sealed to the filter assembly body  48  and locates lower end support  64  and valve plate  70 . Valve plate  70  is sealed to the end cap  49  by o-ring  72 . A bore  178  in valve plate  70  provides a slideable fit for the shaft  42 . O-ring  78  provides a seal between the shaft  42  and the valve plate  70 . The washer  68  retains the o-ring  78 . 
         [0019]    The round shaft  42 , capable of reciprocating motion, extends from the control chamber  34  through a hole  180  defined by a spacer  74  in the control chamber  34 . The shaft  42  then extends through a hole  182  defined by a top guide plate  76 , along a central axis of the filter screen  40 , through the hole  176  in the washer  68 , and through the hole  178  in the valve plate  70 . The lower end of the shaft  42  exits the filter assembly  6  through the valve plate  70  and then the exit port  60  defined by the end cap  49 . O-ring  80  provides a water tight seal above the top guide plate  76 . 
         [0020]    The wiper  44  is fixed on the shaft  42  and reciprocates within the filter screen  40 . The wiper  44  preferably has a frusto-conical shape with an annular knife edge formed by its downward-facing, larger diameter edge  45 . The outside diameter of the wiper  44  is selected so that the wiper  44  will maintain contact with the filter screen  40  along the entire outside edge  45  of the wiper  44 . The wiper  44  preferably is made from a flexible or resilient material. The wiper assembly  36  is fixed to the shaft  42  by means of a stop  82  and a locking nut  84 . 
         [0021]    The control chamber  34  is used to control the position of the wiper assembly  36  through the development of forces which reciprocate the shaft  42  along its longitudinal axis. The control chamber  34  is preferably in the shape of a cylinder. The central axis of the control chamber  34  is aligned with the central axis of the filter screen  40 . A passage  184 , sized to receive the shaft  42 , connects the control chamber  34  to the fluid flow passage  52 . The spring  46  is situated about the spacer  74  and between an upper annular flange  90  of the spacer  74  and a bottom  186  of the control chamber  34 . The spring  46  provides an upward biasing force on a piston seal  86  to move the shaft  42  and the wiper  44  upward. The piston seal  86  also transmits hydraulic forces to the shaft  42  when the control chamber  34  is pressurized by a flow of control water to move the wiper  44  in the other direction. The drive cylinder  47  defines a vent hole  88  extending from the control chamber  34  below the piston seal  86  to outside of the filter assembly  6  to atmosphere. The vent hole  88  insures that the pressure beneath the piston seal  86  will remain atmospheric and allows the piston seal  86  to reciprocate in the control chamber  34 . 
         [0022]    More specifically, the spring  46  has a diameter sized to fit inside the control chamber  34  cylinder and has one end resting on the bottom surface  186  of the control chamber  34 . The spacer  74  preferably has a cylindrical shape. The upper annular flange  90  of the spacer  74  rests on the top end of the spring  46 . The spring  46  is preferably a helical spring, and the diameter of the cylindrical portion of the spacer  74  is such that it fits inside the spring  46  and provides lateral support for the spring  46  while not impeding axial motion of the spring  46 . The diameter of the circular flange  90  is selected so that it is small enough to fit inside the control chamber  34  without causing excessive friction with the sides of the control chamber  34  while being large enough to retain the spring  46 . The bias of the spring  46  is chosen so that in the absence of a predetermined hydraulic pressure from above, such as when the system is in a flow off condition, the spring  46  will urge the spacer  74 , and thus, the piston seal  86  and shaft  42 , to an upward position. 
         [0023]    The piston seal  86  is fixed to the shaft  42  above the spacer  74  and is held in place by a mounting washer  92  and a locking nut  94 , which may be attached to the shaft  42  by threads  95  along the upper end of the shaft  42 . The piston seal  86  provides an essentially watertight seal with the control chamber  34 . Hydraulic forces generated by control water flowing into the control chamber  34  through the port  32  when the irrigation system is in a flow “on” condition will urge the piston seal  86  downward against the bias of the spring  46 , thereby compressing the spring  46  and causing the shaft  42  to move downward. 
         [0024]    Filtered particulate matter is discarded from the filter assembly  6  via one or more grooves  96  defined by the lower region of the shaft  42 . The grooves  96  are positioned axially along the shaft  42  so that when the shaft  42  is in its extreme upward position, the grooves  96  reside entirely above the valve plate  70 , and the o-ring  98  seals against the shaft  42 . When the shaft  42  is in its extreme downward position, the grooves  96  reside entirely below the valve plate  70 , and the o-ring  98  again seals against the shaft  42 . However, when the shaft  42  is in an intermediate position, such as during the upward or downward stroke of the shaft  42 , the grooves  96  bridge the washer  68  and the valve plate  70  and create a passage for the flow of particulate matter and unfiltered water out of the filter assembly  6 . 
         [0025]    With reference to  FIG. 3 , the pressure regulating valve  4  has a main body  98  defining an inlet  10  and an outlet  12 . The main body  98  is preferably constructed in four segments  100 ,  102 ,  103  and  104 , which may be joined by a number of screws,  106 ,  107  and  108 , and sealed together by o-rings  110  and  112 . The inlet  10  and the outlet  12  are designed for connection to piping or other conduit, such as by threads  114  and  116 , respectively, or by friction engagements. The pressure regulating valve  4  comprises three main chambers defined by the body  98 : a system pressure chamber  118 ; an outlet chamber  120 ; and the lockout chamber  26 . 
         [0026]    The system pressure chamber  118  is separated from the outlet chamber  120  by a valve seat  122  which defines an aperture  124 . An o-ring  126  provides a water tight seal between the valve seat  122  and the main body  98 . At the opposite end of the system pressure chamber  118  from the valve seat  122 , there is a rolling diaphragm  128 . The rolling diaphragm  128  is supported in an axially displaceable manner by a spacer  130  which can reciprocate in a spring chamber  132 . A flange  134  on the spacer  130 , and a bottom plate  136  of the system pressure chamber  118  prevent the upward motion of the spacer  130  into the system pressure chamber  118 . The spacer  130  is supported by a spring  138 . The spring  138  biases the spacer  130  and rolling diaphragm  128  upward toward the system pressure chamber  118 . The amount of spring bias is preselected by the position of an adjustment bolt  140 , which can be turned to move the position of the bottom end of the spring  138 . The further the adjustment bolt  140  is turned into the main body  48 , the greater the spring  138  is pre-loaded and, thus, the greater the spring bias. The adjustment bolt  140  includes a larger diameter threaded portion  142  for engagement with threads  144  on the spring chamber  132  and a smaller diameter portion  146  which fits inside the spring  138 . The spring is preferably a helical spring. 
         [0027]    A pressure regulator shaft  148  is mounted to the rolling diaphragm  128 . A screw  129  fixes the spacer  130  to the pressure regulator shaft  148 . The pressure regulator shaft  148  extends through the aperture  124  in the valve seat  122  and into the outlet chamber  120 . The flow valve  8  is fixed to the pressure regulator shaft  148  and held in place by a locking nut  149  and includes a valve head  123  sized to seat on the valve seat  122  to seal the aperture  124  when the diaphragm  128  and shaft are in their downward positions designed to prohibit flow through the valve  4 . The flow valve head  123  and the rolling diaphragm  128  are sized such that the hydraulic force on the diaphragm  128  generated by the pressure of water in the system pressure chamber  118  will be equal to the opposing upward force on the flow valve head  123 . 
         [0028]    The function of the pressure regulating valve  4  is to supply, within practical limits, a flow of water at a predetermined constant pressure regardless of the flow rate. The system water supplied to the inlet  10  may be at varying pressures but must be maintained at a higher pressure than the desired pressure at the output  12 . Since the water pressure supplied to the system pressure chamber  118  creates equal and opposite forces on the rolling diaphragm  128  and the flow valve head  123 , the location of the pressure regulator shaft  148  is determined by the upward force of the spring  138  opposed by the downward hydraulic force of the pressure in the outlet chamber  120  acting on the flow valve head  123 . Thus, if the pressure in the outlet chamber  120  decreases for any reason, the downward hydraulic force on the flow valve head  123  decreases and spring  138  will move the pressure regulator shaft  148  upward, causing the flow valve head  123  to open to increase the flow rate sufficiently and restore the pressure in the outlet chamber  120  to the desired value. Conversely, a pressure increase in outlet chamber  120  will cause the downward hydraulic force on the flow valve head  123  to increase and movement of the regulator shaft  148  downward will decrease the flow rate and maintain the desired output pressure. 
         [0029]    The flow valve  8  also functions as an on/off valve. A lockout piston shaft  28  extends from the lockout chamber  26  into the outlet chamber  120  and is capable of reciprocating motion. The lockout piston shaft  28  includes an upper annular flange  150  and a piston seal  152 . The piston seal  152  may be mounted to the shaft  28  using a washer  154  and a locking nut  156 . The piston seal  152  provides an essentially water tight fit with the lockout chamber  26 , dividing the chamber  26  into an upper portion  26   a  above the seal and a lower portion  26   b  below the seal  152 . A vent port  158  provides fluid communication between the lower portion  26   b  of the lockout chamber  26  and the outlet chamber  120 , enabling pressure equalization between the lower portion  26   b  of the lockout chamber  26  and the outlet chamber  120 . 
         [0030]    The pressure of the control water in the upper portion  26   a  of the lockout chamber  26  determines the position of the lockout piston shaft  28 . The lockout piston shaft  28  is biased towards an upward position by a lockout spring  160 . The preferred lockout spring  160  is a helical spring that surrounds a portion the lockout piston shaft  28 . One end of the lockout spring  160  rests against the bottom surface  27  of the lockout chamber  28  and the other end presses against the upper annular flange  150  of the lockout piston shaft  28 . 
         [0031]    When the solenoid-actuated valve  2  is open, control water can flow freely through the solenoid-actuated valve  2  to join the flow from the outlet chamber  120  via the passage  38 , and to the port  162  of the lockout chamber  26  via the passage  22 . Thus, the control water supplied to the port  162  of the lockout chamber will essentially be at the same pressure as the outlet water pressure. In this situation, the net hydraulic force on the lockout piston seal  152  will be zero, and the bias of the spring  160  will hold the lockout piston shaft  28  in an upward position. 
         [0032]    When the solenoid-actuated valve  2  is closed, the entire flow of control water from the restrictor  16  is directed into the lockout chamber  26  via the port  162 . This flow pressurizes the upper portion  26   a  of the lockout chamber  26 , forcing the lockout piston shaft  28  downward. 
         [0033]    The lockout piston shaft  28  is linked to the pressure regulator shaft  148  by a slideable pin  164 . The bottom portion of the lockout piston  28  and the top portion of the pressure regulator shaft  148  have central axial bores  166  and  168  aligned with each other and sized to receive the slideable pin  164 . The depth of the bores  166  and  168  and the length of the slideable pin  164  are determined so as to allow vertical play when the lockout piston shaft  28  is in its extreme upward position, so that the regulator  4  can control the pressure in the outlet chamber  120  by varying the spacing between the valve head  123  and the valve seat  122 . More specifically, when the solenoid-actuated valve  2  is open and the system is in a flow “on” condition, the lockout piston shaft  28  is in an upward position, and the vertical play in the slideable pin  164  allows the pressure regulator shaft  148  to move freely in conjunction with the rolling diaphragm  128 . This allows the flow valve  8  to function as a pressure regulating valve. The pin  164  also allows the lockout piston shaft  28  to move downward and engage the pressure regulator shaft  148  until the flow valve  8  closes off when then lockout piston shaft  28  moves to an extreme downward position. The slideable pin  164  is sufficiently long so as to remain engaged in the bores  166  and  168  of both the lockout piston shaft  28  and the pressure regulator shaft  148  at all times during operation of the pressure regulator  4 . 
         [0034]    When the solenoid-actuated valve  2  is closed, the system is in a flow “off” condition and the upper portion  26   a  of the lockout chamber  26  will be pressurized, forcing the lockout piston shaft  28  to a downward position. In this condition, the slideable pin  164  is forced against the pressure regulating shaft  148 , causing the flow valve  8  to close and shut off flow to the irrigation system. 
         [0035]    The foregoing relates to a preferred exemplary embodiment of the invention. It is understood that other embodiments and variants are possible which lie within the spirit and scope of the invention as set forth in the following claims.