Abstract:
The present invention provides a turbine with dual sets of fins and a stator assembly for directing water onto both sets of fins. The water flow directed to the first set of fins generates slightly more force than the water flow directed to the second set of fins. In this manner, the opposing forces generated by the water flow maintain a more uniform and constant speed of the turbine.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to sprinklers and more specifically pertains to an improved turbine design for regulating the rotation speed of the sprinkler. 
   Sprinkler systems for turf irrigation are well known. Typical systems include a plurality of valves and sprinkler heads in fluid communication with a water source, and a centralized controller connected to the water valves. At appropriate times the controller opens the normally closed valves to allow water to flow from the water source to the sprinkler heads. Water then issues from the sprinkler heads in a predetermined fashion. 
   There are many different types of sprinkler heads, including above-the-ground heads and “pop-up” heads. Pop-up sprinklers, though generally more complicated and expensive than other types of sprinklers, are typically thought to be superior. There are several reasons for this. For example, a pop-up sprinkler&#39;s nozzle opening is typically covered when the sprinkler is not in use and is therefore less likely to be partially or completely plugged by debris or insects. Also, when not being used, a pop-up sprinkler is entirely below the surface and thus generally less obtrusive to the landscape. 
   The typical pop-up sprinkler head includes a stationary body and a “riser” which extends vertically upward, or “pops up” when water is allowed to flow to the sprinkler. Typically, the riser is a hollow tube which supports a nozzle at its upper end. When the normally-closed valve associated with a sprinkler opens to allow water to flow to the sprinkler, two things happen: (i) water pressure pushes against the riser to move it from its retracted to its fully extended position, and (ii) water flows axially upward through the riser, and the nozzle receives the axial flow from the riser and turns it radially to create a radial stream. A spring or other type of resilient element is interposed between the body and the riser to continuously urge the riser toward its retracted, subsurface, position, so that when water pressure is removed, the riser will immediately proceed from its extended to its retracted position. 
   The riser of a pop-up or above-the-ground sprinkler head can remain rotationally stationary or can include a portion that rotates in continuous or oscillatory fashion to water a circular or partly circular area, respectively. More specifically, the riser of the typical rotary sprinkler includes a first portion, which does not rotate, and a second portion, which rotates relative to the first (non-rotating) portion. 
   The rotating portion of a rotary sprinkler riser typically carries a nozzle at its uppermost end. The nozzle throws at least one water stream outwardly to one side of the nozzle assembly. As the nozzle assembly rotates, the water stream travels or sweeps over the ground. 
   The non-rotating portion of a rotary sprinkler riser typically includes a drive mechanism for rotating the nozzle. The drive mechanism generally includes a turbine and a transmission. The turbine is usually made with a series of angular vanes on a central rotating shaft that is actuated by a flow of fluid subject to pressure. The transmission consists of a reduction gear train that converts rotation of the turbine to rotation of the nozzle assembly at a speed slower than the speed of rotation of the turbine. 
   During use, as the initial inrush and pressurization of water enters the riser, it strikes against the vanes of the turbine causing rotation of the turbine and, in particular, the turbine shaft. Rotation of the turbine shaft, which extends into the drive housing, drives the reduction gear train that causes rotation of an output shaft located at the other end of the drive housing. Because the output shaft is attached to the nozzle assembly, the nozzle assembly is thereby rotated, but at a reduced speed that is determined by the amount of the reduction provided by the reduction gear train. An example of a nozzle assembly having this design can be seen in U.S. Pat. No. 4,681,260, which is herein incorporated by reference in its entirety. 
   With such sprinkler systems, a wide variation in fluid flow out of the nozzle can be obtained. If the system is subject to an increase in fluid flow rate through the riser, the speed of nozzle rotation increases proportionally due to the increased water velocity directed at the vanes of the turbine. In general, increases or decreases in nozzle speed then, of course, affect the desired water distribution. 
   Prior art sprinklers attempt to regulate the turbine speed by providing two water paths, one path leading to the turbine and another path bypassing the turbine. In typical designs of this type, pressure actuated valves divert a portion of the water around the turbine in an attempt to reduce the flow hitting the turbine, as seen in example U.S. Pat. Nos. 5,375,768 and 4,681,260, the contents of which are hereby incorporated by reference. 
   While the use of pressure actuated diversion valves within a sprinkler help regulate the water flow to the turbine, they become less than effective in extreme conditions, such as low flow or very high flow. For example, since such pressure valves only open at a certain pressure threshold such valves will not compensate for any fluctuations under that pressure threshold. In a similar manner, once the valve is completely open due to a relatively large water flow, such valves will not compensate for further fluctuations above a maximum pressure threshold. 
   Further, pressure activated valves can become maladjusted over time due to fatigue, wear, or even breakage. Replacement or repair of the valves can be difficult and costly. 
   As a result, there is a long felt need of a turbine rotation regulation device that is sensitive to changes in water flow pressure at any level, yet has an improved lifespan over prior designs. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an improved turbine-stator assembly which is better able to regulate the rotational speed of the turbine over a larger range of fluid flow. 
   It is a further object of the present invention to provide an improved turbine-stator assembly which has a longer lifespan and requires less frequent repair than prior art designs. 
   The present invention is believed to achieve these objects (and other objects not specifically enumerated herein) by providing a turbine with dual sets of fins and a stator assembly for directing water onto both sets of the fins. The water flow directed to the first set of fins generates slightly more force than the water flow directed to the second set of fins. In this manner, the opposing forces generated by the water flow maintain a more uniform and constant speed of the turbine. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a top view of a regulating turbine according to the present invention; 
       FIG. 2  illustrates a perspective view of the regulating turbine of  FIG. 1 ; 
       FIG. 3A-3C  illustrates various views of a stator assembly according to the present invention; 
       FIG. 4  illustrates a top view of a regulating turbine according to the present invention; and 
       FIG. 5  illustrates a side view of a sprinkler with a regulating turbine according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Generally, a turbine of a sprinkler is positioned over a stator while being coupled to a rotational transmission responsible for causing the sprinkler head to rotate. As water enters the sprinkler, the stator directs the water to the turbine, causing the turbine to rotate. Thus, the turning turbine drives the sprinkler transmission and the rotating sprinkler head. An example of such an arrangement is shown and discussed in U.S. Pat. Nos. 5,720,435 and 5,375,768, which are incorporated herein by reference. Since turf irrigation highly prefers constant rotational velocity of the sprinkler head, it remains important to regulate the rotational speed of the turbine. 
   Prior art sprinklers have relied on various stator designs in an attempt to regulate turbine speed. However, such prior art designs typically did not hold the rotation speed of the turbine to remain substantially constant during wide variations in fluid flow. 
   Looking to  FIGS. 1-3C  and  5 , a regulating turbine  100  and stator  110  of a sprinkler  101  are illustrated according to the present invention. The regulating turbine  100  includes drive fins  102  to drive rotation of the regulating turbine  100  and brake fins  104  mounted on the external circumference of the turbine  100  to provide opposing forces to drive fins  102 . As water flow increases or decreases, the fins  102  and  104  provide the same overall ratio of rotational force on the regulating turbine  100 , thus resulting in a generally constant rotational speed of the regulating turbine  100 . 
   The regulating turbine  100  preferably has a plurality of drive fins  102  disposed around an inner diameter of the regulating turbine  100 . Each of these drive fins  102  are angled to provide rotational force derived from a stream of water directed towards it. Around the outer diameter of the regulating turbine  100  are braking fins  104 , aligned longitudinally along the axis of the regulating turbine  100 . As a result, when rotating, these braking fins  104  create a smaller but oppositely directed force to that produced by the drive fins  102 . 
   As seen best in  FIG. 5 , the regulating turbine  100  is positioned above a stator  110  which directs oncoming water to the turbine  100 . Both the turbine  100  and the stator  110  are preferably located in a lower region of the sprinkler  101 , below the sprinkler head  103  and transmission  105 . A shaft mount  108  is positioned in the center of regulating turbine  100  by struts  106 , mounting to sprinkler transmission shaft  112 . The sprinkler transmission shaft  112  in turn couples to the sprinkler transmission  105  which ultimately drives the sprinkler head  103 . 
   As seen in  FIGS. 3A-3C , the stator  110  is composed of a stator base  119 , having an overall disk-shape with a center aperture. Two protrusions  113  extend from the surface of the stator base  119 , enclosing a channel  113   a  with a water port  114  at the end. A bypass valve member  111  is positioned within the aperture of the stator base  119  and is further connected to valve stem  117 , creating a bypass valve  121 . A spring  115  is positioned to press against a lower area of the stator base  119  and valve stem  117  so as to bias the bypass valve member  111  to a sealed or closed position. 
   Water flows against the stator  110 , moving up channels  113   a  and out water ports  114 . While the relationship of the turbine fins  102  and  104  are constant, the flow path from the water ports  114  and the bypass valve  121  are variable, depending on the water flow. At low flow rates, most of the water flows through the water ports  114  and contacts the drive fins  102 , while very little water escapes from the bypass valve  121  to contact the braking fins  104 . At higher flow rates, the water not only flows through the water ports  114  at a greater rate, but also forces the bypass valve member  111  upward, opening up the bypass valve  121 . The angled design of the bypass valve member  111  directs water radially outwards from the center, towards the brake fins  104 . Thus, the bypass valve member  111  changes the proportion of water directed at the turbine from mostly aimed at the drive fins  102  at lower flow, to mostly aimed at the braking fins  104  at a higher flow. Since the water is less efficiently directed at the braking fins, since there are fewer braking fins  104  than drive fins  102 , and since the braking fins  104  include less of an angle than the drive fins  102 , the rotation of the regulating turbine  100  remains substantially constant. 
   For example, the water ports  114  preferably have a diameter of 0.109 inches, which allows the bypass valve  121  to open when the water flow reaches about 10 GPM. At 10 GPM, little if any water passes through the aperture bypass valve  121  since it is still substantially blocked by bypass valve member  111 . Thus the breaking fins  104  have a minimal breaking effect on the regulating turbine  100  since they contact a small amount of water. 
   When the initial water flow reaches about 12 GPM, the flow from the water ports  114  remains at about 10 GPM while the bypass valve  121  allows about 2 GPM or about 20% of the total water flow through. As the total initial water flow increases above about 12 GPM, the amount of water that passes through the bypass valve  121  also increases, and is thus directed towards the braking fins  104 . In this respect, the force applied to the breaking fins  104  is proportional to the ratio between the flow of the bypassed water to the flow of the drive water from water ports  114 . 
   The rotational speed of the regulating turbine may be adjusted or varied according to the user&#39;s preference by, for example, varying the size and angle of drive fin  102 , varying the size and angle of brake fin  104 , and varying the size of water port  114 . In a preferred embodiment, the angle of the drive fins  102  are 45 degrees and the angle of the braking fins  104  are 5 degrees. 
     FIG. 4  illustrates an alternative preferred embodiment of a regulating turbine  150  according to the present invention. As with the previously described embodiment, the regulating turbine  150  includes drive fins  154  with a center shaft mount  158  held in place by struts  156 . However, the regulating turbine  150  includes multiple angled brake fins  152  disposed around an outer diameter of the regulating turbine  150 . By increasing the number of brake fins  152  and fixing them at an angle at least somewhat opposite to the drive fins  154 , additional braking force may be created. For example, in this embodiment the angle of each drive fin  154  may be 45 degrees and the angle of each brake fin  152  may be 5 degrees. 
   Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.