Abstract:
A top for a pop-up type irrigation sprinkler that utilizes a riser that pops up from a stationary sprinkler body in accordance with an embodiment to the present invention includes a cap which is threadedly attached to the sprinkler body; a co-molded seal positioned in a center of the cap with a riser opening in the center thereof, wherein the seal prevents water from leaking out of the sprinkler between the cap and the sprinkler body and between the seal and the riser.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of the priority of Provisional Application No. 60/682,996 filed May 20, 2005, the contents of which are specifically incorporated by reference herein. 
     
    
     BACKGROUND  
       [0002]     Sprinklers with co-molded (two shot) rubber seals that provide a seal between the riser and body of a sprinkler are known. However, these sprinklers do not have a design that allow for a co-molding manufacturing process that provides the rubber material for the riser seal as well as the seal between the top and sprinkler body.  
         [0003]     U.S. Pat. No. 4,316,579 illustrates one example of a riser seal and discusses desirable features of the sprinkler riser seal. However, the riser seal of this patent does not provide a seal between the top and the sprinkler body.  
         [0004]     Accordingly it is desirable to provide a sprinkler that avoids the problems noted above.  
       SUMMARY OF INVENTION  
       [0005]     A top for a pop-up type irrigation sprinkler that utilizes a riser that is movable up and down in a stationary sprinkler body in accordance with an embodiment to the present invention includes a cap which is threadedly attached to the sprinkler body and a co-molded seal positioned in a center of the cap with a riser opening in the center thereof, wherein the seal prevents water from leaking out of the sprinkler between the cap and the sprinkler body and between the seal and the riser.  
         [0006]     A co-molded seal for use in a riser type irrigation sprinkler that utilizes a cap connected to a stationary sprinkler body in accordance with an embodiment of the present invention includes at least one hard plastic portion formed in a first step of a two shot molding process and an elastic portion made of an elastic material that is formed to surround the hard plastic portion in a second step of the two step molding process, wherein the elastic portion provides a seal to prevent water from leaking out of the sprinkler between the cap and the sprinkler body and between the seal and the riser.  
         [0007]     A method of making a co-molded seal for use in a riser type irrigation sprinkler that utilizes a cap connected to a stationary sprinkler body in accordance with an embodiment of the present application includes steps of forming a hard plastic portion of the co-molded seal in a mold in a first molding step, retaining the hard plastic portion of the co-molded seal in the mold, switching molding cores for use with the mold and forming an elastic portion of the co-molded seal in the mold in a second molding step, wherein elastic material surrounds the hard plastic material. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]      FIG. 1  shows a cross section of a sprinkler with the riser in the retracted position utilizing a top in accordance with an embodiment of the present application and showing the sealing interfaces.  
         [0009]      FIG. 2  is a cross section of the sprinkler top of  FIG. 1  identifying section lines for subsequent figures and showing the co-molded rubber and plastic material portions of the seal.  
         [0010]      FIG. 3  is a cross section of the top of  FIG. 1  identifying the plastic portion of the seal.  
         [0011]      FIG. 4  is a sectional view on cut line E-E of  FIG. 2  identifying the plastic and rubber portions of the co-molded seal.  
         [0012]      FIG. 5  is a sectional view on cut line F-F of  FIG. 2  identifying the plastic and rubber portion of the co-molded seal.  
         [0013]      FIG. 6  is the cross section view on cut line G-G of  FIG. 2  identifying the plastic and rubber portion of the co-molded seal.  
         [0014]      FIG. 7  shows a cross sectional view a sprinkler including another embodiment of the top of the present application with an upper grit wiper seal added and purge flow opening provided by raising location of low pressure internal seal.  
         [0015]      FIG. 8  shows a top in accordance with another embodiment of the present application including a cartridge co-molded unitary seal. 
     
    
     DETAILED DESCRIPTION  
       [0016]     A sprinkler top configuration in accordance with the present invention utilizes a top that is manufactured such that the plastic material that is first shot in a portion of a mold is retained. Thereafter, the cores on both sides of the retained hard plastic portion are changed for use with the desired second shot of elastic material that is used as the sealing material to seal both the sprinkler riser and the sprinkler body. This co-molded seal configuration allows for manufacture of the sprinkler cover using a unitary seal that can be manufactured in a single tool with a two shot type molding machine that is well known in art. Further, using the two shot molding process, the amount of high cost thermoplastic rubber required is reduced and the rigid plastic provides support for the rubber portion to prevent the rubber portion from shrinking with age and interfering with proper function of the riser retraction into the sprinkler body.  
         [0017]      FIG. 1  illustrates a sprinkler utilizing a top  1  including a co-molded seal  1   a  of the present application. The riser  30  is positioned in the stationary body  20  of the sprinkler. The spring  50  is utilized to bias the riser  20  into a retracted position, as illustrated in  FIG. 1 . In this position, the riser  30  is pushed down by spring  50  which is positioned between the ring  51  around the bottom of the riser  30  the under side of the top  1  of the sprinkler.  
         [0018]     The under surface  49  of the nozzle top  40  contacts raised rib edge  9  of the rubber portion of the seal  1   a  of the top  1  to provide a seal to stop the further flow of water once the sprinkler riser  30  is retracted by spring  50  back into the body  20 .  
         [0019]     Lower internal seal lip  8  of the seal  1   a  provides low pressure sealing between the top  1  and the riser  30  during the period that pressure is rising in the sprinkler housing  20  and pushing the riser  30  upward out of the sprinkler body  20  to prevent any substantial water flow blow-by.  
         [0020]     When the sprinkler riser  30  is fully up, high pressure sealing will be provided by the riser shoulder  31  being sealed against surface  7  around the bottom circumference of the seal  1   a  of the sprinkler top  1 . This is a preferred configuration since the flat surface  31  is pressed by the high sprinkler operating pressure against the flat surface  7  around the bottom circumference of the rubber seal to provide a high pressure, leak tight seal. In contrast, conventional sprinklers typically utilize two conical shaped elements and typically stick one cone into the other taking advantage of the angular tolerance between the two cone shaped element to simplify production. That is, they do not utilize the riser shoulder  31  to form a tight seal with the top  1 . As a result, in conventional sprinklers of this type, the riser tends to stick-up even after the pressure is turned off on the sprinkler.  
         [0021]      FIG. 2  illustrates a cross section of the sprinkler top  1  of  FIG. 1 . As illustrated, the sprinkler top  1  preferably includes the cap  2  which is attached to the body  20  of the sprinkler, preferably utilizing the threads  2   a . The seal  1   a  of the top  1  may be molded to the cap  2  if desired. The lip  4  of the seal ensures that water will not leak out between the top surface of the stationary body  20  of the sprinkler and the cap  2  when the cap is secured to the body  20 . The flange  5  and lower lip  6  ensure that water will not leak between the sidewall of the body  20  and the cap  2  when the cap is secured to the body  20 . Further, as noted above, the lower internal seal lip  8  ensures that water does not flow out of the sprinkler between the seal  1   a  and the riser  30 . In the top  1  of  FIG. 2 , the riser  30  ( FIG. 1 ) moves up and down through the seal  1   a  and is guided by the sidewalls  13  thereof. The outer surface of the sidewalls  13  are preferably made of an elastic flexible material. The seal  1   a  preferably includes a hard plastic ring  3  that is surrounded by the elastic material. The hard plastic ring  3  helps to add structural support to the elastic material, particularly in the area of the internal seal  8  as illustrated. The lines E-E, F-F, and G-G illustrated in  FIG. 2  show the locations of the cross sections illustrated in  FIGS. 4-6  which are described in further detain below.  
         [0022]      FIG. 3  illustrates a cross section of the top  1  in accordance with an embodiment of the present application, in which the reference numerals  11  and  12  are used to refer to the hard plastic portions of the seal  1   a  and reference numeral  10  refers to the elastic (or rubber) material surrounding the hard plastic portions. As can be seen in  FIG. 3 , the plastic ring  11  extends around the periphery of the seal  1   a  to provide structural support. The rib  12  is also mad of hard plastic and supplies structural support in the vertical direction. The rib  12  may extend upward from the ring  3  of  FIG. 2 , for example if desired. The ring  11  will provide structural support for the elastic material near the top of the seal where the lip  4 , flange  5 , and lower flange  6  provide a seal between the top  1  and the body  20 . The rib  12  (and ring  3 ) provide support for the elastic material in the area of the lower internal seal  8 , for example.  
         [0023]      FIG. 4  is an illustration of a cross section of the top  1  of  FIG. 2  as viewed from line E-E. As illustrated, the plastic ribs  12  may be spaced apart and preferably positioned longitudinally in the sidewall  13  of the seal  1   a  and surrounded by elastic material. The lips  6  and  8 , as noted above, are also preferably made of the elastic material so as to ensure a tight seal between the seal  1   a  and the sidewall of the body  20 , and the riser  30 , respectively.  
         [0024]      FIG. 5  is an illustration of a cross section of the top  1  of  FIG. 2  as viewed from line F-F. As can be seen in  FIG. 5 , the flange  5  may include protrusions that extend upward periodically as does the elastic material  10 .  
         [0025]      FIG. 6  is an illustration of a cross section of the top of  FIG. 2  as viewed from line G-G. Lip  4  is preferably made of the elastic material to ensure a good sea between the top  1  and the top surface of the sidewall of the body  20 . As illustrated, the material that is used to form the lip  4  may be provided via the elastic material of flange  5 .  
         [0026]      FIG. 7  shows a cross section view of a sprinkler utilizing a top  1  with a shortened seal  1   a  in accordance with another embodiment of the present application. As illustrated, the lower internal seal lip  8  of the seal  1   a  in  FIG. 7  which provides low pressure sealing between the top  1  and the riser  30  and provides minimum resistance when the spring  50  retracts the riser  30  when sprinkler pressure is turned off, is positioned above a joint  60  where the spray nozzle  40  is attached to the riser  30 .  
         [0027]     During manufacture of the riser  30  and/or the nozzle housing  62 , a bevel and/or slots  63  may be provided either on the riser or nozzle housing to provide a momentary purge flow around the water activated low pressure internal riser seal  8  during the up stroke of the riser to allow flushing any grit or foreign material out of the upper portion of the seal. During the upward movement of the riser  30 , while the sprinkler is pressurizing, the under surface  49  is now lifted off the rib edge  9  (see  FIG. 1 ) or the grit wiper lip seal  70  at the upper end of the seal  1   a  as shown in  FIG. 7 . Thus, the purge flow can pass around the nozzle housing  62  due to slot  64  around the outside of the nozzle housing  62  and through the opening between the nozzle top piece  65  and the housing  62  as shown in  FIG. 7 .  
         [0028]     The upper end grit wiper seal lip  70  is upwardly directed and surrounds the riser  30  and nozzle housing  62  and scrapes the stem of the riser clean during pop-down of the riser when the water pressure is turned off.  
         [0029]     This tends to minimize the dirt being pulled back into the seal during retraction and that which can be easily purged out again upon re-pressurizing as described.  
         [0030]     As shown in  FIG. 8 , in accordance with an embodiment of the present application, the top  81  (similar to top  1  of  FIG. 1 ) may be separated from the co-molded (two-shot) unitary seal  1   a  which is embodied in cartridge  100 . The top  81  simply includes a hole  101  in which the co-molded seal cartridge  100  is inserted into.  
         [0031]     The co-molded seal cartridge  100  includes a supporting hard plastic ring  91  around the outside which can be retained in a portion of the mold during the two shot molding process along with plastic support core  83 . After the ring is molded, core changes are performed on both sides of the hard plastic support core  83  and the ring  91  which are to be covered with the elastic seal material during the second shot of the two-shot plastic molding machine process.  
         [0032]     This seal cartridge  100  then is able to be manufactured in a single two shot molding machine process to include both the desired riser low pressure lip seal  88 , high pressure static circumferential to riser seal surface  87  of the elastic seal material and the sprinkler housing lip seal  86  on the single unitary seal cartridge for sealing between the riser and the housing.  
         [0033]     This seal cartridge is also shown with lip  89  angled inward to provide a riser down stroke wiper seal.