Abstract:
A turbine for a sprinkler is disclosed for self-governing its rotational velocity. As a rate of fluid through the sprinkler increases, particularly when air is used to flush the sprinkler system, a portion of the turbine shifts outwardly so as to decrease alignment of vanes located thereon with directed water streams for controlling the rotation of the turbine.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of pending U.S. patent application Ser. No. 11/182,379, filed Jul. 15, 2005, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a water-driven rotary sprinkler and, in particular, to a rotary sprinkler having a speed-control apparatus. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many current irrigation systems utilize a combination of water emission devices or sprinklers coupled together by a system of irrigation pipes for delivering water to the sprinklers. In some environments, such as large scale irrigation of agricultural lands, the sprinkler system is principally above ground and is designed to be moved from one location to another. In other environments, the sprinkler system is principally installed under a ground surface, with an emission portion either co-located with the ground or designed to extend from a retracted position when the system is turned-on or activated. 
         [0004]    As the systems installed within the ground are designed to be generally permanently installed, problems arise due to weather conditions. As is known, the water typically delivered by the sprinkler system expands when it freezes. The presence of fertilizer or other chemicals in the water is usually not sufficient to reduce the freezing point sufficiently, and most parts of the United States, for instance, experience winter air temperatures sufficient to freeze the water. 
         [0005]    The entirety of the sprinkler system is not necessarily susceptible to the freezing. For instance, the irrigation pipes running generally parallel to the ground surface may be buried to a depth sufficient to be below a frost line, and vertical pipes, risers, and stems may be used with the emission device so that most water will drain downward when the system is de-activated. Such a design, however, may still fail to clear all of the water out, while requiring significantly more materials and labor to construct or repair. 
         [0006]    The most common approach to preparing the irrigation system and sprinklers for impending cold weather is a winterization procedure in which high-pressured or compressed air is blown into the system. The air passes through the entire system and simultaneously dries the system and drives water from the pipes, sprinklers, and other controls. 
         [0007]    Problems may arise from the winterization of sprinklers utilizing water-driven components. One type of sprinkler utilizes the flow of water therethrough to power the sprinkler, and many of these sprinklers are rotary sprinklers where the flow of water drives a motor or other mechanism for rotating a sprinkler head. Such sprinklers tend to present a great problem with winterization. 
         [0008]    More particularly, these rotary sprinklers include a sprinkler head rotatably supported by a generally non-rotating housing. The non-rotating housing is often a riser which moves between a retracted position generally within a stationary housing buried in the ground surface and an extended position generally extended from the stationary housing to a position above the ground. Water flowing through the sprinkler typically contacts a water-driven structure such as a turbine having vanes so that a portion of the kinetic energy of the water is imparted to and rotates the turbine. A speed-reducing drive mechanism is operably coupled to the turbine and to the sprinkler head so that the high-speed rotation of the turbine (in the order of 1000-2000 revolutions per minute, though some operate as low as 500 revolutions per minute) is reduced so that the sprinkler head rotates at approximately ⅓ revolution per minute. 
         [0009]    In the absence of any control and for a constant nozzle size, the rate of rotation for the turbine is generally dependent only on the pressure of the water flowing therethrough and on the size of a nozzle or orifice directing the water into the turbine. Under normal operating conditions, pressurized water flows through the sprinkler and causes the high rate of rotation for the turbine, which, as mentioned above, can be on the order of 1000-2000 revolutions per minute. Accordingly, when high-pressured air is injected through the system for winterization, an even higher resultant velocity is experienced by the turbine. Such higher velocity can be on the order of 40,000 revolutions per minute, and it is communicated through the sprinkler via the drive mechanism to the sprinkler head and to any other internal components. 
         [0010]    Winterization using air creating this higher velocity can lead to damage in a rotary sprinkler. The principal concern comes from devices operating at speeds that are orders greater than for what the components were designed. This can result in unpredictable behavior, particular due to an eccentricity in a spinning component. Moreover, the friction and heat generated by the high-speed rotation has a negative effect on the components and can rapidly progress to failure by the components. 
         [0011]    Currently, there are a number of mechanisms in existence for reducing the speed of a turbine or drive mechanism of a rotating sprinkler due to excessive flow. Bypass valves allow a portion of the water to pass directly through a stator structure instead of being focused at the turbine vanes. The velocity of the air against the turbine is generally dependent on the size of the orifice directing the air against the turbine and on a pressure drop across the stator. The reduction in pressure above the orifice due to the opening of a bypass valve may hold the pressure across the stator constant, but is simply not sufficient to lower the velocity of the air being directed at the turbine. 
         [0012]    Another method for controlling rotation due to high flow utilizes centripetal force to shift two portions into frictional contact. Regardless of the efficiency or long-life of such a design, were this method relied upon during winterization, the amount of friction would be far in excess of expected levels for water operation. Accordingly, such friction devices serve to accelerate the failure of sprinklers that are winterized with pressurized air. 
         [0013]    Accordingly, there is a need for a rotary sprinkler with a design improved for winterization. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0014]      FIG. 1  is a cross-sectional view of a pop-up rotary sprinkler including a turbine for rotating a sprinkler head; 
           [0015]      FIG. 2  is a perspective view of the turbine, the deflector plate, and the stator assembly of the rotary sprinkler of  FIG. 1 ; 
           [0016]      FIG. 3  is a top plan view of the turbine of  FIG. 2  in a normal operating condition; and 
           [0017]      FIG. 4  is a top plan view of the turbine of  FIG. 2  shifted from the normal operation condition to a deflected condition. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    Referring initially to  FIG. 1 , there is illustrated a rotary sprinkler  10  for distributing water radially therefrom. The sprinkler  10  includes a water-driven mechanism which includes a turbine  50 . The sprinkler  10  has a stationary housing  12  having a lower end  14  for threaded connection with a source pipe (not shown). Under normal operating conditions, the sprinkler  10  receives pressurized water from the source pipe, and under winterization conditions, compressed air is forced through the source pipe and through the sprinkler  10 . 
         [0019]    The sprinkler  10  includes a movable housing or riser  16  for rotatably supporting a sprinkler head  18 . In  FIG. 1 , the riser  16  is shown retracted as it would be when not activated by pressurized fluid. When activated by the flow of fluid through the sprinkler  10 , the riser  16  telescopically extends from the stationary housing  12  so that the sprinkler head  18  is above and clear of the stationary housing  12 . More specifically, the extended position allows a nozzle (not shown) in the sprinkler head  18  to be positioned above the stationary housing  12 . As will be discussed below, the flow of fluid through the sprinkler  10  powers the sprinkler head  18  in a rotational manner to distribute water in a radial pattern from the nozzle. 
         [0020]    The sprinkler  10  distributes water in an arcuate extent preselected by a user or installer. To enable this feature, a reversing mechanism  20  is located in the sprinkler head  18  which cooperates with a deflector plate  22  located in a lower portion of the riser  16 . In operation, the extent of the arcuate pattern is selected by a user, which can be up to 360°. For a full rotary sweep of 360°, the sprinkler head  18  simply continues rotating in a circle. For any sweep short of 360°, the sprinkler head  18  reaches one limit of the rotation, and then reverses direction. 
         [0021]    More specifically, when the sprinkler head  18  reaches one limit, a portion rotating therewith engages an upper portion  24  of a rod, referred to herein as a trip rod  26 , causing the same to rotate a short amount. A lower portion  28  of the trip rod  26  is secured to the deflector plate  22  so that the short rotation made by the trip rod  26  when engaged by the sprinkler head  18  rotates the deflector plate  22  a small amount, in the order of 19°. As can be seen in  FIG. 2 , the deflector plate  22  has deflector openings  32  for directing water flow in a direction, either clockwise or counter-clockwise, within the riser  16 . In one position, flow is received by one or a set  34  of deflector openings  32  oriented in one direction, and the small rotation of the deflector plate  22  allows fluid flow to pass through one or a set  36  of oppositely oriented deflector openings  32 . Each set  34 ,  36  preferably includes three deflector openings  32 . The deflector plate  22  is provided with one or more torsion springs (not shown) so that the deflector plate  22  is generally held in the selected position. 
         [0022]    More specifically and with reference to  FIG. 1 , water flows through ports  38  defined by short tubular towers  39 , which extend upward from the top of a stator plate  40 . Water flowing upwardly through a lower portion  17  of the riser  16  contacts a bottom side  42  of the stator  40  and is forced into the ports  38 . For one direction of flow, the deflector plate  22  is positioned with the deflector opening set  34  aligned with a top opening  44  of the port  38  and for the other direction, the deflector plate  22  is shifted so that the other deflector opening set  36  is aligned with the top opening  44  in the port  38 . 
         [0023]    The direction of water flow from the deflector plate  22 , which is dictated by the alignment of the deflector opening sets  34 ,  36  with the port opening  44 , determines the direction of rotation for the sprinkler head  18 . An apparatus utilizing such a reversing feature is described in commonly-assigned U.S. Pat. No. 6,732,950, incorporated herein by reference in its entirety. The water discharged from the deflector opening sets  34 ,  36  drives the turbine  50  in a rotary fashion. 
         [0024]    As illustrated in  FIG. 2 , the turbine  50  is secured with a hollow turbine drive shaft  52  positioned around the trip rod  26 . In this manner, the turbine  50  and turbine drive shaft  52  are free to rotate relative to the trip rod  26 . When water strikes the turbine  50  in a particular direction, the turbine  50  is driven in the same clockwise or counter-clockwise direction of the water. Towards this end, the turbine  50  includes generally vertically aligned vanes  56  extending from a turbine ring  58 . The vanes  56  have a pair of opposed lateral sides  56   a  that are slightly arcuate from the vertical plane. The turbine  50  further includes a generally central hub  60  secured with a lower portion  62  ( FIG. 1 ) of the turbine drive shaft  52 . The turbine ring  58  and hub  60  are connected by spokes  64 , an arrangement which will be described in greater detail below. 
         [0025]    The turbine drive shaft  52  operably couples turbine  50  to a drive mechanism  70 . The turbine  50  under normal operating conditions, being driven by water, rotates at a rate typically ranging between 1000-2000 revolutions per minute. Were the sprinkler head  18  to rotate at such a rate, the water emitted therefrom would tail, that is, achieve only a short throw distance and be deposited a short distance from the sprinkler head  18 . Accordingly, the drive mechanism  70  provides appropriate speed reduction. 
         [0026]    Towards this end, the drive mechanism  70  includes a series of gear modules  72 , each providing a gear ratio. In this manner, the gear modules  72  reduce the high-speed rotation of the turbine  50  to a low-speed rotation for the sprinkler head  18  in the order of ⅓ revolution per minute. The turbine drive shaft  52  is secured with a drive gear  74  of the drive mechanism  70  such that the drive gear  74  co-rotates with the turbine  50  and the turbine drive shaft  52 . The drive mechanism  70  further includes an output hub  76  for receiving a drive shaft  78  connected to the sprinkler head  18 . Accordingly, rotation of the turbine  50  is communicated to the drive mechanism  70 , which reduces the speed and increases the torque for the rotation, and the drive mechanism  70  communicates the reduced speed to the sprinkler head  18  for rotation thereof. 
         [0027]    During winterization, high-pressured air is forced through the sprinkler  10 . The air flow increases the rate of rotation of the turbine  50  several fold. At a high rotation rate, a high friction is experienced between the turbine drive shaft  52  and the trip rod  26 , which extends through the drive mechanism  70 , and in other components of the sprinkler  10 . The turbine  50  is thus constructed to reduce the rotation rate, particularly during this winterization process. In a preferred form, the turbine  50  is made from material, such as nylon with carbon fiber filler, having a high thermal conductivity to enable the turbine  50  to dissipate heat for the friction. 
         [0028]    As noted above, the turbine  50  includes the hub  60  connected to the turbine ring  58  by spokes  64  and vanes  56  extending from the ring  58 . With reference to  FIGS. 3 and 4 , the spokes  64  can be seen as a pair of spokes  64   a ,  64   b  positioned relatively close to one another in one quadrant of the ring  58 . The ring  58  is in the form of a split ring. More specifically, it is generally 360° with a split  80 . The split  80  is defined by a first end  82  positioned generally adjacent to the spoke  64   a  and a second end  84  facing the first end  82  arcuately across the split  80 . Viewed another way, the ring  58  forms an arcuate arm  90  extending from the second end  84  to the spoke  64   b . The arm  90  preferably spans a majority of the ring  58 , such as spanning through 270° or more of the arcuate extent of the ring  58 . 
         [0029]    During non-operation, the first and second ends  82  and  84  may contact each other or may be separated by a relatively small distance at the split  80 , in the order of 0.030 inches, as depicted in  FIG. 3 . During normal water operating conditions, the first and second ends  82 ,  84  separate or widen a relatively small amount. For example, they may separate on the order of 0.010 inches, in addition to the small distance noted above, for a ring  58  having an inner diameter of approximately 0.750 inches, while the radial extent of the vanes  56  forms a circle having an outer diameter of approximately 1.000 inches. 
         [0030]    As the rotational velocity of the turbine  50  increases, such as due to high-pressure air through the sprinkler  10 , the split  80  increasingly widens. More specifically, the ring arm  90  deflects outwardly due to centripetal force. Normal operation conditions are typically sufficient to deflect the arm  90  only a slight amount, such as that noted above as an example. However, under high rotational velocity due to air flow, the arm  90  deflects such that the split  80  widens to a relatively significant amount. For example, it may widen to approximately 0.150 inches. It should be noted that design parameters of the turbine  50  may be altered such that the split  80  may similarly widen for excessive flow rates of water. It should also be noted that these design parameters may include varying the mass and the stiffness of the arm  90  so that the deflection is activated at a desired speed. 
         [0031]    The turbine  50  having the arm  90  deflected outward experiences less of a drive force from the fluid flow through the sprinkler  10 . Particularly, it is noted that the deflector openings  32  direct fluid streams directly into the vanes  56  at the proper angle for driving the turbine  50 . When the arm  90  deflects outward, a significant number of the vanes  56  shift at least partially out of alignment with the deflector openings  32 . Therefore, a portion of the air through the deflector openings  32  passes by the turbine  50  without contacting the vanes  56  or contacting the vanes  56  in an inefficient manner. Thus, the contribution of any energy to the rotation of the turbine  50  is significantly reduced. 
         [0032]    It should be noted that the turbine  50  includes dead spokes  64   c . These spokes  64   c  assist in balancing the turbine  50  which, as noted herein, may rotate at high speeds. Furthermore, the dead spokes  64   c  increase the amount of heat, such as that generated by friction between the turbine drive shaft  52  and the trip rod  26 , that may be dissipated from the turbine  50 . The flow of fluid across and through the turbine  50  also assists in dissipating heat. The dead spokes  64   c  are separated from the ring  58  by a short distance  67 , such as in the order of 0.050 inches. 
         [0033]    The design of the turbine  50  reduces the rotation rate during winterization to an acceptable rate. To compare, a turbine (not shown) of the prior art is similarly constructed to the turbine  50 , though without the split  80  and with the ring  58  not forming the arm  90 . Accordingly, a prior art turbine has a generally static shape and does not deflect outwardly under high rotation. During winterization, an expected rotation rate for the prior art turbine under common and particular air pressure conditions may be as high as approximately 48,000 revolutions per minute. In contrast, the present turbine  50  under generally identical air pressure conditions has a rate of rotation of approximately 16,000 revolutions per minute. In this manner, the friction between the turbine drive shaft  52  and trip rod  26  is drastically reduced, and the above-described issues with high-speed rotation are alleviated or reduced. 
         [0034]    The amount of friction at this reduced speed is within an acceptable amount for relative long-term life of the sprinkler  10 . During winterization testing, the sprinkler  10  including the split-ring turbine  50  did not show significant amounts of wear after 75 minutes of high-pressure air flow. 
         [0035]    It should be noted that the flow of high-pressure air through the sprinkler  10  provides a retarding force or drag on the outwardly deflected turbine arm  90 . As stated above, water flowing upwardly through riser lower portion  17  contacts the stator bottom side  42  and feeds through the ports  38 . In the event pressure below the bottom side  42  exceeds a predetermined level, a bypass valve  100  opens. 
         [0036]    As can be seen in  FIG. 1 , the bypass valve  100  includes a moving member  102  biased downward by a spring  104 . In this manner, the moving member  102  is received against a valve seat, presently represented in the form of a shoulder  106  surrounding a bypass opening  108  formed in the stator  40 . When a pressure differential between the top and bottom of the stator  40  exceeds the predetermined level, the bias of the spring  104  is overcome, and the moving member  102  is forced upward and away from the shoulder  106 . As such, the bypass opening  108  is opened such that fluid may pass through the stator  40  without passing through the ports  38 , as described above. 
         [0037]    When the bypass valve  100  is at least partially opened, a bypass portion of the air flows around the moving member  102  and flows upward and radially outward. As can be seen, the bypass portion of the air thus flows around or radially outboard of the deflector plate  22 , without passing through the deflector openings  32 . This bypass air flow is disruptive to the air flow directed through the ports  38  to the deflector openings  32 . More importantly, once passing through the sprinkler  10  to the turbine  50 , this bypass portion of the air flow, generally vertically flowing, retards the rotational motion of the turbine  50 . In this manner, the reduced rotation rate of the turbine  50  is, in part, influenced by the bypass valve  100 . 
         [0038]    While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described apparatuses and methods that fall within the spirit and scope of the invention as set forth in the appended claims.