Part-circle sprinkler with reversible stator
FIELD OF THE INVENTION 
     The present invention relates to part-circle sprinklers having nozzles which are automatically rotated between preselected first and second positions. 
     BACKGROUND OF THE INVENTION 
     Automatic part-circle sprinklers are known in the art. Many are designed to attach to underground water pipes and incorporate pop-up heads which rise above the ground when water is supplied to the sprinkler and which lie flush with the ground when not in use. 
     The limitations of the part-circle sprinklers found in the prior art are numerous. First, most utilize complicated control mechanisms which are susceptible to being jammed by the various debris flowing through the water pipes of most sprinkler systems. As a result, expensive screens are required to protect the control mechanisms. 
     Second, in many of the part-circle sprinklers found in the prior art, the limits of coverage of the sprinkler are set internally within the sprinkler and thus partial disassembly of the sprinkler is usually required when these limits are to be changed. 
     Third, in those sprinklers which provide a precise adjustment of the area of coverage, the sprinkler rotates only to the preset limit of rotation. As a result, the presence of any wind or a slight misadjustment of the area of coverage often results in the outer limits of the area not being sprayed with water. 
     Finally, most of the devices found in the prior art have no means for maintaining a constant speed of rotation when sudden changes occur in the volume of water supplied to the device. As a result, these volume changes cause erratic operation of these part-circle sprinklers. 
     Accordingly, it is a principal object of this invention to reduce the complexity of the control mechanism required in a part-circle sprinkler. 
     It is another object of this invention to simplify the adjustment of the limits of rotation of a part-circle sprinkler. 
     It is still another object of this invention to insure that the outer limits of the predetermined area of coverage of a part-circle sprinkler receive adequate water. 
     It is a final object of this invention to prevent volumetric changes in the water supplied to a part-circle sprinkler from disturbing its speed of rotation. 
     SUMMARY OF THE INVENTION 
     The present invention, in a broad aspect, involves the use of a reversing stator and accompanying actuator to control the rotation of a part-circle sprinkler. The part-circle sprinkler includes a housing adapted for connecting to a supply of water under pressure, an impeller for rotating in response to the water flowing axially through the housing and incident on the blades of the impeller, transmission means driven by the impeller, and a sprinkler head, incorporating a nozzle, adapted for rotation by the transmission. 
     The reversing stator is located directly below the impeller and provides one or more channelized streams of water against either side of the blades of the impeller and thereby causes the impeller, sprinkler head, and nozzle to either rotate in a clockwise or counterclockwise direction. The position of the reversing stator, and thus the angular orientation of the channelized streams, is controlled by an actuator which incorporates means for predefining the area of coverage of the part-circle sprinkler and which provides a direction-reversing stimulus to the reversing stator. 
     In accordance with one feature of the invention, the upwardly-directed, channelized streams are smoothly deflected against the impeller one or more vanes in the reversing stator. Each of the vanes may be symmetric and have opposing surfaces convergently curving toward an apex disposed in the path of the incoming water. By the action of the actuator in shifting these vanes on either side of the streams, the impeller is driven in a clockwise or counterclockwise direction. The shifting of the vanes can cause an angular change in the direction of the deflected water of up to 120° degrees. Contact of the reversing stator with the actuator is made in a V-shaped guide projecting from the circular wall to provide for easy assembly of the stator into the housing. 
     In accordance with another feature of the invention, the actuator comprises a pair of adjustable fingers or stops, which provide the initial limits of rotation of the sprinkler head, and a resilient shaft or drive arm which applies a direction-reversing stimulus to the reversing stator. The fingers or stops may be on the interior or the exterior of the sprinkler head and may be movable or fixed. In the preferred embodiment, the fingers are located on the exterior of the sprinkler head and are movable. The resilient shaft or drive arm is attached to the housing. At one end of the shaft is a crank arm which makes contact with the fingers. At the other end is a blade which rides in a slot at the bottom of the V-shaped guide in the reversing stator. 
     As the sprinkler head rotates, one of the fingers approaches the crank arm. When the initial limit of rotation, defined by the position of the finger, has been reached, the finger turns the crank arm and exerts a torque on the shaft. The shaft then starts to twist as the force of the water on the curved vanes prevents the reversible stator from rotating as the head moves past the limit of rotation defined by the finger. The blade prevents the shaft from turning and thus causes the torque in the shaft to rapidly accumulate. When the torque in the shaft is greater than the force of the water on the curved vanes in the reversing stator, the shaft snaps the reversing stator to an orientation, with respect to the upwardly-directed streams, that is opposite to its previous orientation. As a result, the streams are directed to the opposite side of the impeller blades and the sprinkler head reverses its direction. The process then repeats for the other finger. In this manner, the sprinkler is caused to continually oscillate between and slightly past the limits of rotation established by the fingers. The ability to rotate slightly past the limits of rotation established by the fingers provides a unique &#34;overcenter&#34; action which assures a positive reversing action. 
     In accordance with still another feature of the invention, the reversing stator mounts to the housing by means of two other stators whose primary function is to create the upwardly-directed streams which are deflected by the reversing stator against the impeller. The first or bottom stator is fixedly mounted to the bottom of the housing in the path of the incoming supply of water. This stator has vertical vanes directs the incoming supply to the second stator. The second or middle stator divides the stream of water coming from the first stator into a plurality of high velocity, upwardly-directed streams. The second stator also has vertical vanes and is movably positioned above the first stator. 
     The second stator includes downwardly-depending stops for preventing it from rotating and an upwardly-depending stop for limiting the rotation of the reversing stator. The rotation of the reversing stator is limited such that the V-shaped vanes may only move across the path of the upwardly-directed streams of water. 
     In accordance with still another aspect of the invention, all three stators are interconnected by a shaft which freely passes through the reversing stator and the bottom stator, and which is rigidly attached to the middle stator. The shaft is of such a length and interconnects the stators in such a manner that the middle stator and the reversing stator may move upwardly away from the bottom stator in response to increases in the volumetric flow of the water supply. This separation diverts some of the water away from the middle stator and allows the operation of the part-circle sprinkler to continue without a change in the speed of rotation of the nozzle. A spring is positioned between the bottom of the shaft and the bottom stator. The spring biases the middle stator and the reversing stator against the bottom stator. The strength of the spring provides a control over the speed of the transmission as water having a volumetric flow rate producing a force on the middle stator greater than that provided by the spring is diverted. This feature allows the sprinkler to operate with different size nozzles without a significant change in the nozzle rotation speed or in the pressure of the water leaving the nozzle. 
     In accordance with the final feature of the invention, the sprinkler may be adapted to be mounted underground and thus be of the &#34;pop-up&#34; head variety. In this regard, the housing may be fitted with a sleeve which would allow it to move upwardly when water is supplied to the sprinkler, the upward movement lifting the nozzle above the surface of the ground. The sleeve would incorporate a stop for limiting the upward travel of the housing and a seal for preventing water from leaking from the sleeve. Additionally, a spring would be positioned on the exterior of the housing between the bottom of the housing and the top of the sleeve. The spring would bias the housing underground when the supply of water to the sprinkler was discontinued. 
     Other features and advantages of the present invention will become apparent from a consideration of the following detailed description and from the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a part-circle sprinkler constructed according to the present invention and containing a pop-up head; 
     FIG. 2 is a plan view of the invention, taken along plane II--II of FIG. 1, showing the relationship of the resilient switching arm and the adjustable fingers which define the limits of rotation of the sprinkler head; 
     FIG. 3 is a plan view of the invention, taken along plane III--III of FIG. 1, showing the positioning of the reversing stator relative to the second directing stator and the resilient drive arm prior to any water entering the sprinkler; 
     FIG. 4 is a detail view of FIG. 1, taken along plane IV--IV, showing the positioning of the vanes of the reversing stator relative to the vanes of the second directing stator; 
     FIG. 5 is a plan view of the invention, taken along plane V--V of FIG. 1; 
     FIG. 6 is a detail view of the invention, partially in cross-section taken along line VI--VI of FIG. 1, showing the orientation of the switching arm to the reversing and directing stators; 
     FIG. 7 is a plan view of the invention, taken along plane VII--VII of FIG. 1, showing the orientation of the vanes of the second directing stator relative to the vanes of the first directing stator; 
     FIG. 8 is a plan view of the invention showing the operation of the reversing stator in changing the direction of the water incident on the impeller as the drive arm makes contact with one of the adjustable fingers; 
     FIG. 9 is a detail view of FIG. 8, taken along plane IX--IX, showing the movement of the reversing stator relative to the second directing stator; 
     FIG. 10 shows the operation of the reversing stator in changing the direction of the water incident on the impeller when the drive arm makes contact with the other adjustable finger; 
     FIG. 11 is a detail view of FIG. 10, taken along plane XI--XI, showing the movement of the reversing stator relative to the second directing stator; 
     FIG. 12 and FIG. 13 are detail views of the drive arm and the reversing stator prior to the drive arm changing the orientation of the stator. 
     FIG. 14 shows the separation of the reversing and second directing stators away from the first directing stator as the volume of the water entering the sprinkler increases; and 
    
    
     DETAILED DESCRIPTION 
     Referring more particularly to the drawings, FIG. 1 shows a part-circle sprinkler 20. All the components of the sprinkler 20 are located in a housing 22. At the top of the housing 22 is mounted a rotating sprinkler head 32 containing a nozzle 38 by which water is discharged. The sprinkler head 32 attaches to the housing 22 by means of a plurality of supporting arms 48 attached to a transmission means 50 mounted within the housing 22. Movement of the sprinkler head 32 relative to the housing 22 is aided by a thrust bearing race 40. The bearing race 40 is sealed from the housing by an O-ring 42. 
     The sprinkler head 32 is rotated by a transmission means 50 which attaches to the housing 22 by means of a plurality of supporting braces 51. The transmission means 50 is driven by an impeller 52. The direction of the water incident upon the blade of the impeller 52 determines the direction of rotation of the impeller 52, and of the sprinkler head 32 and its accompanying nozzle 38. As discussed below, the direction of water incident on the impeller 52 is determined by a reversing stator 54 which is controlled by actuator. The actuator has three components: a switching arm 66 and two adjustable fingers 44 and 46. Also, and is seen from FIG. 1, the direction of the flow of the water through the housing is entirely axial. 
     In the preferred embodiment, the part-circle sprinkler 20 is of the pop-up head variety. In this regard, the housing 22 has attached to it an outer sleeve 24 which is held in position by a threaded retaining cap 30. The sleeve 24 connects to an underground conduit by means of a fitting 28. When no water is supplied to the sprinkler 20, a spring 26 biases the housing 22 into the sleeve 24 until a cover plate 34, attached to the sprinkler head 32 by screw 36, contacts the surface of the ground. When water is supplied to the sprinkler 20 through the fitting 28, the force of the water lifts the housing 22 in the sleeve 24 such that the sprinkler head 32 is positioned above the surface of the ground. 
     The water entering the sprinkler 20 first passes through a directing stator 58 (hereinafter referred to as the first directing stator). The flanges of the first directing stator 58 are positioned against a step 21 in the bottom of the housing 22. The stator 58 is oriented by means of a key in the housing 22 riding in a slot in the stator 58. 
     As can be seen from FIG. 5, the first directing stator 58 contains a flat, horizontally-oriented circular surface 61 which has a hole in its center. Structural support for the stator 58 is provided by a plurality of vanes 86. The stator 58 performs two functions. First, it directs the flow of water from the inlet to the straightening vanes 86 of a second stator 56 mounted directly above it. Second, it functions as the lower half of a bypass valve used to maintain a constant speed of nozzle rotation. As will be explained, the operation of the valve involves the lifting of the second stator 58 off of the first stator 58. Accordingly, until such lifting as occurred, the first stator 58 provides a supporting surface or seat for the second stator 56. 
     The second directing stator 56 is fixedly attached to a shaft 60 which passes freely through the first directing stator 58. As can be seen from FIG. 6, a pair of stops 88 and 90, depend downwardly from one of the vanes in the second directing stator 56 to straddle one of the straightening vanes 86 in the first directing stator 58. These stops 88 and 90 prevent the second directing stator 56 from rotating relative to the first directing stator 58. 
     The second directing stator 56 has a plurality of vertical &#34;straightening&#34; vanes 76, each which appear, in cross section, as an inverted, open, rectangular channel. As shown in FIG. 7, the orientation of the second directing stator 56 relative to the first directing stator 58 positions these vanes 76 above the water passing through the first directing stator 58. The vanes 76 in the second directing stator 56 modify the stream of water passing from the first directing stator 58 into a plurality of narrow, high velocity, streams of water. These streams are directed to a reversing stator 54 which deflects the streams against one or the other side of the blades of the impeller 52, thereby causing the impeller 52 to turn the transmission means 50 (and therefore the sprinkler head 32 and nozzle 38) in either a clockwise or a counterclockwise direction. Accordingly, it is seen that the two primary functions of the second directing stator 56 are to create a plurality of channelized or &#34;straightened,&#34; high velocity streams of water from the water flowing from the first stator 58, and also to direct these streams against the reversing stator 54. In addition to these functions, the second stator 56 acts as a part of the bypass valve and provides support for the reversing stator 54. 
     As shown in FIGS. 1 and 6, the reversing stator 54 is rotatably attached to the shaft 60 which passes through all three stators 54, 56, and 58. As can be seen from FIG. 4, the reversing stator contains a one or more vanes 74. As shown in FIGS. 3 and 4, the cross section of each vane 74, relative to an axis parallel to the axis of rotation of the reversing stator 54, is symmetric. The opposing sides of each vane are curved surfaces which converge toward an apex disposed in the path of the channelized streams of water from the second directing stator. Such a shape provides for a smooth flow of water from the second stator 56 through the reversing stator 54, and onto the blades of the impeller 52. Although this vane shape is considered optimal, other shapes could also be used--such as a &#34;V&#34; shape. 
     The position of the vanes 74 relative to the streams of water passing from the second directing stator 56 determines the orientation of the water incident upon the blades of the impeller 52. As can be seen from FIG. 3, the second directing stator 56 has a stop 84 upwardly-depending from one of its vanes 76. This stop 84 limits the rotation of the reversing stator 54 such that its curved vanes 74 may only move across the path of the upwardly-directed streams of water from the second directing stator 56. As shown in FIG. 1, the reversing stator 54 is located directly below the impeller 52. The reversing stator 54 includes a circular wall which surrounds the impeller 52 to shield the impeller from all water other than that deflected by the vanes 74 in the reversing stator 54. 
     The position of the reversing stator 54, and thus the angular orientation of the deflected channelized streams from the second directing stator 56 is controlled by an actuator. The two primary elements of the actuator are a pair of adjustable fingers 44 and 46 and a resilient switching arm 66. The fingers 44 and 46 provide the initial limits of rotation of the sprinkler head 32. As shown in FIGS. 1 and 2, these fingers 44 and 46 frictionally attach to the exterior of the sprinkler head 32. In this manner, they may be moved to change the area of coverage of the sprinkler. Alternatively, the fingers may be rigidly attached to the interior of the sprinkler head 32 and thereby predefine a certain area of coverage. 
     The other part of the actuator is a resilient switching arm 66. This switching arm 66 makes contact with the fingers 44 and 46 and applies a direction-reversing stimulus to the reversing stator 54. The resilient switching arm 66 passes from the interior to the exterior of the housing 22 through a small passage. As shown in FIGS. 12 and 13, the portion of the passage communicating with the interior of the sprinkler flares outwardly at surface 33 to allow movement of the switching arm 66. An O-ring seal 31 prevents water from entering the passage. 
     The upper end 68 of the resilient switching arm 66 is L-shaped to form a crank arm and is positioned to contact each of the fingers 44 and 46 as the sprinkler head 32 alternately rotates them toward the upper end 68 of the resilient switching arm 66. The lower end 70 of the resilient switching arm 66 is shaped as a narrow blade and makes contact with the reversing stator 54 in a V-shaped guide projecting from the circular wall of the reversing stator 54. As can be seen from FIG. 6, the V-shaped guide from the reversing stator 54 comprises a pair of members 72 and 73 projecting outwardly from and diagonally down one section of the circular wall. The V-shaped guide formed by these members 72 and 73 is open at the bottom, so as to allow the lower end 70 of the resilient switching arm 66 to be irrotatably positioned in the opening. 
     FIG. 3 shows the orientation of the reversing stator 54 to the second directing stator 56 and to the resilient switching arm 66 prior to any water entering the sprinkler 20. When no water is incident upon the reversing stator 54, and when the upper end 68 of the switching arm 66 is not in contact with one of the fingers 44 and 46, the switching arm 66 positions the reversing stator 54 such that the curved vanes 74 of the reversing stator 54 are approximately between the vertical vanes 76 of the second directing stator 56. As soon as water enters the sprinkler 20, the first and second directing stators produce the previously-described plurality of high velocity, channelized streams and cause the reversing stator to rotate in one direction. The upwardly-depending stop 84 from the second directing stator 56 limits this rotation such that the bottom of each curved vane 74 in the reversing stator 54 will move only to the outer edge of the channelized stream of water incident upon the vane 74. That is, the bottom of each vane 74 will become aligned with one edge of a vane 76 in the second directing stator 56, as shown in FIG. 4. In this manner, all the vanes 76 will deflect the channelized streams of water from the second directing stator 56 to the same orientation, thereby causing the impeller 52 to rotate. 
     The rapid rotation of the impeller 52 is geared down by the transmission means 50 to cause the sprinkler head 32 to slowly rotate. After striking the impeller, the water flows through the housing 22 to the sprinkler head 32 and passes through the nozzle 38 into the preselected area of coverage. As shown in FIG. 4, the vertical vanes 76 in the second directing stator 56 are slightly rounded at the bottom to reduce the turbulence produced as the streams pass from the first directing stator 58 to the second directing stator 56. This reduction in turbulence helps the second directing stator 56 to produce a plurality of highly-channelized streams of water to be deflected by the reversing stator 54 onto the blades of the impeller 52. 
     As shown in FIGS. 8, 9 and 12, as the sprinkler head 32 rotates, one of the fingers 46 approaches the upper or crank arm end 68 of the resilient switching arm 66. When the initial limit of rotation, defined by the position of the finger 46 has been reached, that finger 46 makes contact with and turns the upper end 68 of the switching arm 66 and causes a torque to be exerted on the shaft of the switching arm 66. As a result, the switching arm 66 then starts to twist at the flared opening 33 of the housing passage. As shown in FIG. 12, the force of the water on the vanes 74 in the reversing stator 54 prevents the reversing stator 54 from rotating as the sprinkler head 32 moves past the limit of rotation defined by the finger 46. The irrotatable positioning of lower or blade end 70 of the switching arm 66 in the V-shaped guide in the reversing stator 54 prevents the arm 66 from rotating and thus causes the torque in the arm to rapidly accumulate. When the torque in the arm 66 is greater than the force of the water on the curved vanes 74, the switching arm 66 releases the accumulated torque by snapping the reversing stator 54 to an orientation, with respect to the upwardly-directed streams from the second directing stator 56, that is opposite to its previous orientation. As a result, these streams are deflected to the opposite side of the impeller blades and the sprinkler head 32 thus reverses its direction as the impeller is driven in the opposite direction. The process then repeats as the sprinkler head 32 approaches the other finger 44. The &#34;overcenter&#34; rotation of the sprinkler head 32, which results from the resiliency of the switching arm 66, thus insures a positive reversal of direction of the reversing stator 54, which results from the resiliancy of the switching arm 66. 
     FIGS. 10, 11, and 13, show the process by which the direction-reversing stimulus is applied to the reversing stator 54 by the switching arm 66 as the limit of rotation defined by the other the finger 44 is reached. As before, the contacting of the finger 44 with the upper end 68 of the switching arm 66 causes a torque to be produced in the shaft 66. The torque in the arm 66 accumulates as the lower end 70 of the arm 66 is prevented from turning by the V-shaped guide projecting from the reversing stator 54. The torque in the arm 66 builds up until it is greater than the force of the water on the curved vane 74 in the reversing stator. At that time, the switching arm 66 straightens, thereby snapping the reversing stator 54 to an orientation opposite to what it had previously. The changing of the orientation of the reversing stator 56 causes the water to be deflected against the other side of the blades of the impeller 52. Consequently, the sprinkler head 32 is caused to rotate in the opposite direction and the entire cycle of oscillating between and slightly past the limits of rotation established by the fingers 44 and 46 repeats. 
     Referring to FIG. 11, it is seen that each of the curved vanes 74 in the reversing stator 54 deflects the water by an angle of approximately 60 degrees. Accordingly, the reversal of the reversing stator 54 by the switching arm 66 causes a net change in the direction of the water incident upon the impeller blades of approximately 120 degrees. Such a substantial change in direction aids in the positive reversing of the streams of water against the blades of the impeller. 
     As shown in FIGS. 6, 8 and 10, the projections 72 and 73 from the reversing stator 54, which comprise the V-shaped guide for the resilient switching arm 56, prevent the switching arm 66 from losing contact with the reversing stator 54 when the switching arm 66 is under the high torque created by the force of the water on the curved vanes 74 and the force of the finger 44 and 46 on the upper end 68 of the arm 66. That is, the high torque produces a twisting in the arm 66 which causes the bottom end 70 of the arm 66 to translate upwardly in the V-shaped guide formed by the projections 72 and 73. However, the length of the lower or blade end 70 of the switching arm 66 is such that it does not lose contact with the slot at the bottom of the V-shaped guide. The arm 66 causes the stator to quickly switch its orientation with respect to the channelized stream produced by the second directing stator 56. As can be seen from FIGS. 8 and 10, therefore, the rotational movement of the reversing stator 54 is always opposite to that of the sprinkler head 32. 
     As is shown in detail in FIGS. 6, 14, all three stators 54, 56, 58 are interconnected by a shaft 60 which freely passes through both the reversing stator 54 and the first directing stator 58 and which is rigidly attached to the second directing stator 56. The shaft 60 is of such a length that the reversing stator 54 and the second directing stator 56 may move upwardly away from the bottom stator in response to increases in the volumetric flow of the water supply. As shown in FIG. 14, as the second directing stator 56 and the reversing stator 54 move away from the first directing stator 56, a gap is created between the first and second directing stators. This separation diverts some of the water away from the second directing stator 56 and allows the operation of the part-circle sprinkler 20 to continue with a constant speed of rotation in spite of the increased volume of water. A spring 62, positioned between the bottom end 64 of the shaft 60 and the first directing stator 58, biases the second directing stator 56 and reversing stator 54 against the first directing stator 58. The strength of the spring 62 thereby provides a control over the amount of upward movement of the second directing stator 56 and the reversing stator 54 away from the bottom stator 58, and thus provides a control over the speed of the transmission means 50. That is, the primary purpose of the valve is to maintain a constant speed of rotation even though the volume of water passing through the sprinkler has increased. This allows the same stator to be used for a wide range of flow rates. The only change necessary to accomodate the different rates is thus made in the nozzle size. 
     The reversing stator 54, and the first and second directing stators 56 and 58 may be molded in a one-piece structure of plastic, or other easily-formable material such as nylon or delrin. In the preferred embodiment, each stator consists of a lightweight, one-piece molded plastic body. 
     The foregoing description of the present invention, a preferred embodiment of the invention has been disclosed. It is to be understood that other mechanical and design variations are within the scope of the present invention. Thus, by way of example and not of limitation, the three stators could be of a material other than plastic; the sprinkler could be designed without a pop-up head for above-ground use; the adjustable fingers and resilient drive arm could be mounted completely within the housing; and, the channelized streams of water deflected by the reversing stator could be produced by means other than two separate directing stators. Accordingly, the invention is not limited to the particular arrangement which has been illustrated and described in detail.