Abstract:
A sprinkler head includes a first housing carrying a center stem having an inlet at an upstream end and an outlet at a downstream end. A second housing is supported within the first housing and encloses a nozzle and a pressure regulator in axially-aligned relationship, defining a flowpath between the inlet and an orifice of the nozzle. The second housing is normally biased to a retracted position but is moveable to an extended position relative to the first housing and to the center stem. A surface of the pressure regulator cooperates with the outlet of the center stem as the second housing moves relative to the first housing to regulate pressure to the nozzle orifice.

Description:
This invention relates to sprinkler heads, and more specifically, to an extendable, retractable sprinkler head incorporating pressure regulation, self-clean and drain check functions. 
     BACKGROUND OF THE INVENTION 
     Sprinkler heads adapted for mounting to fixed risers are well known in the art. Such sprinkler heads, however, are prone to clogging due to debris that may collect in or around the nozzle, particularly during extended periods of nonuse. Above-ground sprinklers are also susceptible to damage from any number of sources due to close proximity to, for example, human traffic, agricultural machines and the like. In addition, typical sprinkler heads do not accommodate changes in line pressure, thereby producing uneven sprinkling patterns. 
     There remains a need for an above-ground sprinkler head that is substantially sheltered during periods of nonuse, that is easy to clean (particularly in the nozzle area), and that automatically accommodates line pressure changes. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In the exemplary but nonlimiting implementations of the invention disclosed herein, an extendable, retractable sprinkler head is provided that is especially useful when mounted above ground on fixed risers (typically, a few inches to about 15 feet above the ground, depending on application). The sprinkler head incorporates an extendable nozzle and water-distribution (or rotor) plate assembly that is normally biased to a retracted position where the nozzle and rotor plate are substantially enclosed. Upon the introduction of water under pressure to the sprinkler head, the line pressure overcomes the normal bias, moving the nozzle and water-distribution plate assembly upward to an extended position. In this way, the critical components of the sprinkler head are enclosed and thus sheltered during periods of nonuse. 
     A built-in pressure regulator device compensates for line pressure changes, and a built-in drain check prevents any back flow when the nozzle and water-distribution plate assembly moves to the retracted position. 
     Another feature relates to a controlled rotational speed of the nozzle and water-distribution plate by means of a viscous damping arrangement. 
     Still another feature relates to the use of a fixed nozzle cleaning pin shaped and arranged to automatically clear the nozzle upon retraction of the nozzle and water-distribution plate. 
     Accordingly, in one aspect, the invention relates to a sprinkler head comprising: a first housing carrying a center stem having an inlet at an upstream end and an outlet at a downstream end; a second housing supported within said first housing and enclosing a nozzle and a pressure regulator in axially-aligned relationship defining a flowpath between said inlet and an orifice of said nozzle, said second housing normally biased to a retracted position but moveable to an extended position relative to said first housing and to said center stem, wherein a surface of said pressure regulator cooperates with said outlet of said center stem as said second housing moves relative to said first housing to regulate pressure to said nozzle orifice. 
     In another aspect, the invention relates to a sprinkler head comprising: a first outer housing adapted to attachment to a riser; a second inner housing normally enclosed in a retracted position within the first outer housing and moveable to an extended operative position; the second housing supporting a nozzle and a rotatable water-distribution plate downstream of the nozzle; the second housing further including first means for continuously regulating pressure of water delivered to the nozzle, second means for controlling speed of rotation of the water-distribution plate, and third means for automatically cleaning the nozzle upon movement of the second housing to the retracted position. 
     In still another aspect, the invention relates to a sprinkler head comprising: a first housing carrying a center stem having an inlet at an upstream end and an outlet at a downstream end; 
     a second housing supported within said first housing and enclosing a nozzle having a nozzle orifice; 
     said second housing normally biased to a retracted position but moveable to an extended position relative to said first housing and to said center stem; 
     a pin fixed to said center stem and extending upwardly through said nozzle orifice in said retracted position but spaced from said nozzle orifice when said second housing is in said extended position, such that said nozzle orifice is automatically cleaned upon movement of said second housing from said extended position to said retracted position. 
     The invention will now be described in detail in connection with the drawings identified below: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross section through a sprinkler head in accordance with a first exemplary but nonlimiting embodiment of the invention; 
         FIG. 2  is a perspective view of a center stem component removed from the sprinkler head shown in  FIG. 1 ; 
         FIG. 3  is another perspective view of the center stem component shown in  FIG. 2 ; 
         FIG. 4  is a perspective view of a nozzle insert removed from the sprinkler head of  FIG. 1 ; 
         FIG. 5  is a perspective view of a water-distribution plate removed from the sprinkler head of  FIG. 1 ; 
         FIG. 6  is a cross section similar to  FIG. 1  but with the sprinkler nozzle and water-distribution plate shown in an extended position; and 
         FIG. 7  is a cross section similar to  FIG. 1  but showing an optional cap applied to the sprinkler head. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to  FIG. 1 , the pop-up sprinkler head  10  is comprised of a housing  12  which includes an upper cylindrical housing portion  14  and a lower cylindrical housing portion  16 , assembled at a threaded joint  18 . A fixed stem  20  (also referred to herein as a “center stem”) is attached to the lower housing portion  16  at a second threaded joint  22 , the stem extending upwardly into the housing  12  along a vertical center axis of the sprinkler head. 
     More specifically, and with further reference to  FIGS. 2 and 3 , the center stem  20  is formed with a lower, relatively larger diameter skirt  24  provided with external threads  26  that engage internal threads  28  on the lower housing portion  16 . The skirt  24  is connected to a relatively smaller diameter adapter  30  by an annular ring-shaped wall  32 . The adapter  30  is formed with internal threads  34  by which the sprinkler head  10  may be attached to an above-ground supply conduit or riser (not shown). In that regard, it will be appreciated that other connection mechanisms may be employed, such as quick connect/disconnect couplers. A center stem portion  36  extends upwardly from the wall  32 , terminating at a closed upper end defined by a top wall  38  formed with an upwardly open, outer blind bore  40  and concentrically-arranged inner blind bore  42  supporting a nozzle-cleaning pin  43  described further below. 
     Adjacent and below the top wall  38 , the center stem portion  36  is provided with one or more circumferentially-spaced, teardrop-shaped apertures  44 . As will be explained in greater detail below, water under pressure will flow into the center stem  20  via an inlet  46  and exit the apertures  44 . 
     Returning to  FIG. 1 , the upper and lower housing portions  14 ,  16  are configured to form two chambers, a lower chamber  48  and an upper chamber  50 . The lower chamber  48  has a relatively larger diameter than the upper chamber  50 , as determined by the annular shoulder  52  at the lower end of the upper housing portion  14  that joins the upper and lower housing portions  14 ,  16 . The chambers  48 ,  50  are sealed from each other as described further herein. 
     Surrounding the center stem  20 , and extending axially within both chambers  48  and  50 , is an extendable and retractable nozzle and pressure regulator (NPR) assembly  54  supported in a manner that enables the pop-up feature of the sprinkler head. 
     The NPR assembly  54  includes a generally cylindrical, preferably metal (e.g., stainless steel) nozzle housing  56  having a relatively larger-diameter lower portion  58  and a relatively smaller-diameter upper portion  60 , joined by an annular shoulder  62 . A nozzle (or nozzle insert)  64  formed with mated upper and lower sections  66 ,  68 , respectively, joined at an annular shoulder  70 , thus permitting the nozzle  64  to be mated to the housing  56 . The nozzle  64  may be made of an elastomeric, tear-resistant material (e.g., polyurethane) or other suitable material. Upstream of the nozzle  64  is a pressure regulator  72  having a uniform outer diameter (or OD) engaged with the inner surface of the lower nozzle housing portion  58 , and engaged at its upper end with the lower edge of the nozzle  64 . 
     The nozzle  64  has a generally dome-shaped inner chamber  74  in the lower nozzle section  68 , formed with a series of inner ribs  76 , best seen in  FIG. 4 , that, along with annular surface  77 , engage and seal against the upper edge of stem  36  as shown in  FIG. 1  when the NPR assembly  54  is retracted to the position shown in  FIG. 1 . A smaller-diameter inner bore  78  extends upwardly from the chamber  74  to a nozzle orifice  80 . 
     The pressure regulator  72  has a nonuniform inner diameter (or ID), including a first upstream (lower) end  82  adapted to engage and seal against the OD of the center stem portion  36 , and an upper end  84  designed to have a clearance or gap  86  between the upper end  84  and the center stem portion  36 . Between the upper and lower ends  84 ,  82  there is an annular recess  88 . 
     The pressure regulator  72  is also formed with a plurality (at least two) of axially extending bores  90 ,  92  communicating between the nozzle inner chamber  74  and an annular space  94  below the pressure regulator  72 . 
     An annular lower spring plate  96  with a center opening  98  is attached to the bottom of the nozzle housing  56  via a series of recesses  100  in the pressure regulator  72  that receive a like plurality of radially extending pins  102  in the plate  96  (see  FIG. 6 ). The OD of the lower spring plate  96  is formed with a plurality of ribs or flutes  97  that mesh with vertical ribs  99  formed on the inner wall of the lower housing portion  16 . This interengagement prevents the plate  96  from rotating during extension and retraction of the NPR assembly  54  as described below. 
     Separating the upper and lower chambers  50 ,  48  is an upper spring plate  104  formed with a downwardly concave, annular groove  106 . A double-lip seal  110  is interposed between the upper spring plate  104  and the underside of the annular shoulder  52  of the upper housing portion  14 . A coil spring  112  is interposed between the upper and lower spring plates  104 ,  96  with the upper end of the spring  112  engaged within the groove  106 . The double-lip seal  110  engages the nozzle housing  56  so as to seal the chamber  48  from the chamber  50 , and thus also prevent debris from entering the lower chamber  48 . 
     Supported on the upper end of the nozzle housing  56  (and thus also a part of the NPR assembly  54 ) is the water-distribution plate assembly  114  which includes a brake housing assembly  116  that controls the rotational speed of a replaceable rotor or water-distribution plate  118 . The water-distribution plate  118 , best seen in  FIG. 5 , is of conventional design, having a series of grooves  120  that are curved in a circumferential direction to impart rotation to the plate when impinged upon by a stream of water emitted from the nozzle orifice  80 . 
     The brake housing assembly  116  includes a brake housing  122  telescoped over the upper end of the nozzle housing  56  and rotatable relative to the nozzle housing. Within the brake housing, there is an offset viscous brake “motor” including a rotatable shaft  124  (extending parallel to the center axis of the sprinkler head) having a lower end received in a bearing recess  126  formed in the lower end of the brake housing, and an upper end which mounts a first gear  128  engaged with a second gear  130  fixed to the nozzle housing. The shaft  124  also mounts a rotor  132  (plastic or metal) adjacent the lower end of the shaft, the rotor located within a chamber  134  closed at its upper end by a shaft bearing  136  and sealed by a double-lip seal  138 , the latter held in place by a retainer  140 . The chamber  134  is filled or partially filled with a viscous fluid such as silicone or the like. The rotational speed of the water-distribution plate  118  will thus be controlled by the geared arrangement between the water-distribution assembly  114  and the rotationally fixed nozzle housing  56 , and specifically by the viscous shear effect between the rotor  132  and the viscous fluid in the chamber  134 . The viscous brake effectively slows the rotation of the water-distribution plate  118  so that the integrity of the streams thrown off the rotor plate is enhanced, thereby increasing the radius of throw of those streams. It will be appreciated that different gear configurations may be utilized to produce non-circular patterns or random hesitation, the latter providing a more uniform sprinkling pattern. 
     A cap or cover  142  is snapped into place over the top of the brake housing  122 , and two or more (preferably three) struts  144  extend upwardly from the cap  142  to support the water-distribution plate  118  in axially aligned relationship with the nozzle orifice. 
     A pair of grease seals  145  is employed in the brake housing assembly  116  and cap  142  to facilitate rotation of the brake housing  122  relative to the nozzle housing  56  and to prevent water (or other debris, such as sand particles) from passing between the brake housing assembly  116  and the nozzle housing  56 . 
     In the retracted position shown in  FIG. 1 , the NPR assembly  54 , including the rotor or water-distribution plate  118  is enclosed within the upper housing  14 , with a radial flange  146  on the water-distribution plate engaged with the upper edge  148  of the upper housing portion. This is the default or normal bias position of the water-distribution plate  118 , as determined by the downward bias of the coil spring  112  on the lower spring plate  96 . 
     When water under pressure is supplied to the sprinkler head  10 , the water will flow through the center stem portion  36  via inlet  46  and into the nozzle housing  56  via the teardrop-shaped apertures  44 , and then to the water-distribution plate  118 . Some water will also flow through the bores  90 ,  92  and exert an upward force on the pressure regulator  72 . As the upward pressure generated by the water line pressure overcomes the downward bias of the spring  112 , the NPR assembly  54  will begin to rise to the extended position shown in  FIG. 6 . 
     With further reference to  FIG. 6 , note that the upper, radially inwardly facing, and convexly curved annular end portion  84  of the pressure regulator  72  will move along the teardrop-shaped apertures  44  and thus restrict flow through those apertures, seeking an equilibrium position where the upward force created by the line pressure of the water and the downward force exerted by the coil spring  112 , are equal. As line pressure increases, the NPR assembly  54  moves upwardly, but the amount of restriction increases (due to the teardrop shape of apertures  44 , noting that the aperture area decreases in an upward direction), and thus the upward force decreases, allowing the spring pressure to push downwardly, again seeking equilibrium. Similarly, if the line pressure decreases, the spring  112  will push the NPR assembly  54  downwardly, thus lessening the flow restriction and increasing flow to counter the spring action. It will be understood that the spring constant of the spring  112  is calibrated or matched to the nominal line pressure so that the continuously sought equilibrium position produces the desired output. 
     When the water or line pressure is cut off, the spring  112  will return the NPR assembly  54  to the retracted position shown in  FIG. 1 . During retraction, the nozzle cleaning pin  43  pushes through the nozzle orifice  80 , thereby clearing the nozzle of any debris. Note that the choice of an elastomeric material for the nozzle is significant in that debris being cleared by the pin  43  will not damage the nozzle. When in the extended or operable position ( FIG. 6 ), the NPR assembly  54  is moved upwardly away from the fixed cleaning pin  43 , thus permitting unobstructed flow through the nozzle orifice  80 . It will also be appreciated that in the extended position, the NPR assembly  54  may be pushed downwardly manually, and then released, resulting in a quick but effective flush of the nozzle without having to shut the system down. 
     When the NPR assembly  54  is returned to the retracted position, the ribs  76  and annular surface  77  of the nozzle will seal against the upper edge of the center stem  36 , thereby providing the drain check function, in that water is prevented from flowing in either direction, i.e., to or from the nozzle chamber  74 . 
     Nozzle orifice sizes may vary depending on requirements, and the pin  43  may or may not need replacement with a nozzle change. For example, if the nozzle orifice were made smaller than the pin OD, then the pin would also need to be changed. If, however, the nozzle orifice were made larger, the pin may not need replacement since it would still be effective to clear the nozzle orifice of debris. 
       FIG. 7  illustrates an optional feature relating to the use of a cap  150  that may be affixed to the top of the sprinkler head  10 . The snap-over (or other substantial equivalent such as bayonet fit or screw thread) fastening arrangement  152  is sufficiently strong to keep the NPR assembly  54  in the retracted position even under line pressure. Thus, any one or more sprinkler heads  10  in an array of heads may be kept closed even when subjected to line pressure, depending on desired watering sequence, patterns and other factors. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.