Abstract:
A pressure regulator is provided that can produce a relatively constant outlet pressure over a range of flow rates. A spring backed diaphragm reacts against the inlet pressure to produce this desired outlet pressure. To provide a range of outlet pressures with a variety of inlet pressures, a spring may be selected from a set of springs having different strength characteristics. The regulator includes a housing with the liquid inlet being located at 90° with respect to the liquid outlet and with a dry chamber on the back side of the diaphragm in which the spring is positioned. Thus, it is easy to remove a cap enclosing the dry chamber and position the desired spring within that chamber. For handling even higher output pressures, a pair of springs may be concentrically positioned in the dry chamber of the housing to react against the inlet pressure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to pressure regulators particularly for use with water distribution systems. 
     2. Description of the Related Art 
     In irrigation systems, sprinkler heads, drip irrigation outlets, or other elements affect the outlet waterflow. Water sources are provided at a variety of pressures and the pressure in a given system may vary as consumption varies. There are limits on pressure that sprinkler heads, drip irrigation elements and electrical flow control valves can withstand, and these limits vary widely. These elements function best when subjected to a preset water pressure. Thus, it is common to provide pressure regulators in water lines to provide a relatively constant pressure over a range of input pressure. The volume flowing through a regulator is also variable depending on the number and type of downstream outlets. Thus, it is desirable that the pressure regulator provide a relatively constant outlet pressure under a variety of input pressures and a range of flow through the regulator. 
     One type of pressure regulator currently being utilized to satisfy the foregoing needs is the so-called “inline” regulator. Such pressure regulators have two main disadvantages. First, the mechanism such as a spring used to regulate the flow is in the flow path. Consequently, the spring is subject to wear, thus diminishing performance and useful life. If the spring must be changed, the regulator must be disconnected from the water line. More importantly, if a different outlet pressure is desired, the entire regulator must be removed from the water line and replaced by one providing the desired outlet pressure. 
     This approach is inconvenient and expensive to the user because of the time required to replace the pressure regulator as well as the expense of purchasing many different pressure regulators. Correspondingly, dealers that sell regulators to end users are forced to keep many different pressure regulators in inventory, and endure the undesirable inventory expense and space. Likewise, manufacturers must produce and inventory this wide range of regulators. 
     Thus, a need exist for a pressure regulator system that eliminates or minimizes these shortcomings. 
     SUMMARY OF THE INVENTION 
     The present invention provides a pressure regulator that overcomes the disadvantages of the prior art. The regulator includes a housing having a water inlet oriented about 90° with respect to a water outlet. A regulator valve positioned in the outlet is connected to a diaphragm extending across a third opening in the housing. A spring reacting against the diaphragm is captured in the third opening by a removable cap. The spring is selected to provide a substantially constant outlet pressure when the diaphragm is subjected to a range of input pressures. A set of springs to provide a variety of preset outlet pressures is provided with the regulator. The user of the regulator can select the spring that corresponds with the desired outlet pressure, remove the cap from the regulator, and position the desired spring in place. Thus, the invention encompasses both the structure of the system as well as the method. 
     The present invention has the advantage that only springs need to be replaced rather than the entire pressure regulator in order to obtain a desired outlet flow pressure. The invention has a further advantage that the springs are kept in a separate dry chamber. Only the cap needs to be removed to replace a spring rather than disconnecting an entire line. An operator need only purchase one regulator and a set of springs rather than many different regulators. This of course also reduces cost for dealers and for manufacturers. Also right angle valves allow for higher flows with less pressure drop, in contrast to inline valves. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a cross-sectional view of one form of the regulator of the invention. 
     FIG. 1B is an enlarged portion indicated by the broken line  1 B in FIG.  1 A. 
     FIG. 2A is an exploded perspective view of the regulator of FIG.  1 A. 
     FIG. 2B is an exploded perspective view of another form of the invention. 
     FIG. 3A illustrates a set of springs to be used with the regulators illustrated in FIGS. 2A and 2B. 
     FIG. 3B is an illustration of the springs to be used in connection with the embodiment of FIG.  2 B. 
     FIG. 4A is a cross-sectional view of the embodiment of FIG.  2 B. 
     FIG. 4B is an enlargement of the portion of the regulator of FIG. 4A as illustrated by the broken line  4 B. 
     FIGS. 5A-5F illustrate performance data of the regulator of FIG.  1 A. 
     FIGS. 5G-5J illustrated performance data of the regulator of FIG.  4 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The pressure regulator of FIG. 1A comprises a one-piece housing  10  having a tubular inlet section  10   a,  a tubular outlet section  10   b,  and a tubular pressure regulation section  10   c.  The outlet section is oriented approximately 90° with respect to the inlet section and is axially aligned with the pressure regulation section. The outer ends of both the inlet section  10   a  and the outlet section  10   b  are provided with internal threads to convert with threaded conduits. The pressure regulation section  10   c,  however, is provided with external threads. 
     The inner end of the pressure regulation section  10   c  is marked by an inwardly extending annular flange  12 . The outer end of the pressure regulation section includes a cap  14  which threads onto the outer end of the housing pressure regulation section. Referring to FIG. 1B, the open end of the cap  14  has an internal cylindrical wall  16  spaced inwardly from the threaded portion  14   a  to define an annular space between it and the threads. This space is slightly larger than the thickness of the cylindrical housing wall outlet  18  so that the housing wall fits into the space when the cap is threaded into place. 
     The inside cylindrical wall of the closed end of the cap  14  flares outwardly to a larger diameter inner surface of the cylindrical wall  16  on the open end of the cap. An adjacent, axially and radially inner cylindrical housing wall  20  is slightly smaller than the diameter of the outlet end  18 . This creates a flat annular flange or seat  22  between those two housing diameters. 
     A diaphragm end  24   a  of a valve stem  24 , is positioned in the pressure regulation section  10   c,  with a valve end  24   b  of the stem being in the housing inlet section. A cylindrical socket  24   c,  seen in FIG. 2A is in the diaphragm end of the valve stem, with the socket open end facing the cap  14 . The outer diameter of the socket closed end  24   d  is slightly smaller than the inner diameter of the housing annular flange  12  so that the valve stem can move axially within the flange. The outside diameter of the open end of the socket is considerably larger than that of the closed end and forms a boss  24   e  having an upper cylindrical portion  24   f  and a lower cylindrical portion  24   g.  These portions are separated by an annular slit open on its radially outer end. 
     An annular flexible diaphragm  26  surrounds the boss  24   e  with an inner annular edge  26   a  of the diaphragm snugly fitting in the slot of boss  24   e.  The inner edge  26   a  of the diaphragm is preferably sonically welded to the boss. The outer periphery of the diaphragm forms an annular lip  26   c  that rests on the housing shoulder  22 . As seen from FIG. 1B, the diaphragm includes a cylindrical portion  26   g  engaging the outer surface of the boss upper cylindrical portion  24   f,  and extending into an annular portion  26   b  having an arch shaped cross-section that enables the diaphragm to flex with pressure changes to which it is exposed. 
     A plastic ring or washer  30  rests on of the diaphragm lip  26   c,  and the internal cylindrical wall  16  of the cap  14  presses against the washer and clamps the lip against the adjacent shoulder  22 . This seals the interior of the housing from the dry chamber within the cap. The cap cylindrical wall rotates on the washer rather than the diaphragm and therefore protects the diaphragm from damage. As seen from FIG. 1B, the washer  30  has an outer annular recess that mates with an upwardly extending annular rib  26   d  to further secure the diaphragm periphery. 
     A coil spring  32  is positioned within the cap  14  with one end engaging the inner end of the cap, and its other end engaging the end  24   d  of the socket. The diaphragm is thus urged inwardly by the spring against the urging of liquid pressure within the housing that reacts against the diaphragm. 
     A valve element or member  34  is attached to the lower end of the valve stem by a fastener  35  or other suitable means, and cooperates with a surrounding annular valve seat  36  within the housing. The valve seat forms the boundary between the housing inlet section  10   a  and the outlet section  10   b.  In the arrangement illustrated, the valve member  34  is positioned on the downstream side of the seat  36 , and the spring  32  is urging the valve element away from the valve seat, or in other words, urging the valve member  34  into the valve open position. The diameter of the valve seat  36  is close to the outside diameter of the valve element  34  such that flow would be substantially shut off if the valve member is moved to a position to engage the valve seat. A plurality of axially extending, circumferentially spaced fins  38  on the inlet side of the valve member  34 , and a plurality of axially extending, circumferentially spaced fins on the outlet side help straighten the flow passed the valve. 
     The housing is preferably made of plastic and is designed to be molded. To enable a mold plug to be withdrawn from the housing, the valve seat  36  and the inside wall of the outlet section extending from the valve seat to the outer end of the outlet section is made as a separate piece. This enables the remainder of the housing to be molded as one piece. The valve seat piece, which can also be molded, is then positioned as shown and permanently attached in that position by suitable means, such as sonic welding. 
     An alternative embodiment of the invention shown in FIGS. 2B,  4 A and  4 B is identical to that of the first embodiment, except that it has a different cap  40  and can accommodate two springs. The cap  40  of the second embodiment threads onto the housing in the same fashion, but the inner and outer diameters of the outer portion of the cap are larger than that of the second. This enables an outer coil spring  42  to be positioned within the cap concentrically surrounding the inner spring  32 . One end of the outer spring is engaged by the cap  46  and the other end engages the end surface of the annular boss  24   e  formed on the valve stem  24 . As seen, the spring  42  has a larger diameter than the spring  24  and is slightly shorter. 
     In operation, water entering the inlet portion  10   a  of the housing flows between the valve element  34  and the seat  36 , and exists through the housing outlet section  10   b.  The water pressure in the inlet section is also applied to the diaphragm and the adjacent portion  5  of the valve stem, urging the valve stem in the valve closing direction against the urging of the spring or springs on the valve stem. If the inlet pressure increases, the valve stem will move in the valve closing direction. If the inlet pressure decreases, the valve will move in the valve opening direction. The force provided by the spring or springs will cause a relatively constant outlet pressure, with a variety of input pressures. The desired flow will typically be determined by an upstream valve or restriction in combination with the flow being permitted by downstream components. With the regulator of the invention, the output pressure remains relatively constant over a wide variety of flow rate. 
     The actual outlet pressure is determined by the strength of the spring, or in the case of the dual spring arrangement, is determined by the combination of the strength of the two springs. Thus, the user may select the desired outlet pressures and simply position that spring in the chamber beneath the regulator cap. For example, a set of six springs such as that shown in each of FIGS. 3A and 3B may be provided to enable the user to elect the spring that will provide outlet pressures of 10, 20, 30, 40, or 50 psi. 
     Preferably, the springs are colored differently to indicate the outlet pressure obtained from it to assist in making the desired choice. The dual spring arrangement is particularly useful when high outlet pressures are desired. With that arrangement, the strengths of the springs are simply added to provide the desired output. Thus, an inner spring calibrated to provide a 10 psi output and an outer spring calibrated to provide a 50 psi output can be utilized when an outlet pressure of 60 psi is desired. Thus, with two sets of springs provided, the full range of outlet pressures may be obtained. Of course, any number of springs may be utilized in whatever outlet pressures are desired. Note that the embodiment of the regulator employing the large cap can be used with only one spring, if desired, and it can be the inner spring or the outer spring. Thus, in that sense, the cap on the first embodiment of the regulator is not necessarily required, although in a single spring arrangement, the small diameter cap is capable of preventing any unlikely buckling of the smaller diameter spring. 
     The regulators of the invention have provided remarkably consistent results. These are shown in FIGS. 5A through 5F for the single spring version for lower outlet pressures and in FIGS. 5G through 5J for the double spring version for higher outlet pressures. As can be seen from the performance data, the selected springs will provide substantially constant outlet pressure with a variety of input pressures and with a wide range of flow rate. This is highly desirable to provide accurate metering of output flow from the devices at the end of the line. Also, accuracy is highly desirable to prevent damage of any downstream electric control valves. The option of changing springs is a particularly desirable feature of the invention in that an end user, say the operator of a golf course, may encounter a wide range of inlet pressures at different facilities. Regulators of the invention enable an operator to simply select the proper spring to provide the desired outlet pressure. This can be done without disconnecting the regulator from the water line. Instead, it is only necessary to unscrew the cap and replace the spring with the desired one. 
     The versatility of providing the desired outlet pressure over a wide range of flows is very advantageous. For example, it may be desirable to have a line leaving the outlet section that is connected to two different lines, each having its own on/off valve. One line may, for example, be connected to a series of sprinkler heads that require high flow, and the other line may lead to drip irrigation outlets that require very low flow. Both control valves may function adequately with the same output pressure. Thus, if the sprinklers are to be operated in the morning and require high flow, the regulator of the invention will provide such, while maintaining a constant outlet pressure. In the afternoon, if it is desired to provide water to the drip irrigation outlets, the regulator will still provide the desired outlet pressure to the control valve with the greatly reduced flow rate.