Abstract:
An actuator assembly for a rotatable sprinkler head includes a base supported for rotation on a stationary platform assembly, the actuator assembly comprising a hub mounted for rotation on a shaft supported in the base; a lever arm pivotally mounted at one end to the hub and extending downwardly toward a stop plate assembly on the platform assembly, the lever arm having a free end extending toward the stop plate assembly; the stop plate assembly configured to define two or more arcuate paths of travel for the lever arm, the paths being radially offset relative to the hub; and wherein the lever arm is adjustable to locate the free end in any of the two or more arcuate paths of travel.

Description:
[0001]    This is a continuation-in-part of provisional application Serial No. 60/280,742 filed Apr. 3, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to agricultural irrigation sprinklers and more specifically to large volume sprinkler heads of the rotary step-by-step type that are capable of being operated in a reversing part circle mode. Sprinkler heads of this type are disclosed in U.S. Pat. Nos. 3,559,887; 3,744,720; 4,153,202; 4,193,548; 4,342,424; and 4,720,045. The invention described herein is applicable to sprinkler heads where the part circle mode of operation includes a cycle having an operative or forward step-by-step rotary movement through a part circle arc of travel and a similar speed step-by-step reverse movement through the same arc of travel.  
           [0003]    Large volume, part circle sprinklers are often used on traveling irrigation systems (travelers), or as the last (i.e., radially outermost) sprinkler (also known as an end gun) on pivot irrigation systems. In either case, there is a need to change the arc of travel at various points during a typical operation. For example, when a large volume sprinkler is used on a traveler, there is typically a sprinkler cart on which the sprinkler is mounted, with a large hose that feeds the sprinkler strung out through the field in the direction of travel that the sprinkler will irrigate, to another cart supporting a hose reel. In operation, the hose reel rotates, pulling the hose in, along with the sprinkler cart. For a typical rectangular field, the farmer would like to start the sprinkler running against the far end or starting point of the field with the sprinkler irrigating a half circle pattern, looking towards the hose reel. After the sprinkler cart is beyond one radius of throw of the far end of the field, the farmer would then like to irrigate an arc of approximately 270° with the un-irrigated piece being directly between the sprinkler cart and the hose reel. This is usually the best traveling distribution curve for the sprinkler cart since the path where the sprinkler cart travels remains as dry as possible, and thus helps prevent the sprinkler cart from becoming stuck. As the sprinkler cart approaches the hose reel at the near end of the lot, the farmer would like to again change the sprinkler to a half circle arc such that the sprinkler irrigates into the field and not onto the hose reel, i.e., the half circle arc would extend away from the hose reel and near end of the lot. These arc changes may also involve matters of safety since the ends of the field are often roads or buildings or some other area that it is desired to keep dry.  
           [0004]    When the large volume sprinkler is used on the end of pivots, it is often used to increase the acreage of ground covered, particularly in the corners of a rectangular field. By intermittently turning the sprinkler on and off, it can be used to irrigate the corners of a square or rectangular field as the pivot is swung in a circle. This is done by turning the sprinkler on as the pivot enters the corner and turning it off as it leaves. By being able to also vary the arc of travel of the sprinkler as the pivot comes into and out of the corner, and as it travels through the corner, a higher degree of accuracy could be obtained while irrigating more of the ground in the corner area of the field.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0005]    The present invention incorporates an arc changer mechanism that allows a large volume sprinkler to operate using different preset arcs of travel in a manner that is simple, reliable, and easy to adjust. The arc changer mechanism is also designed so that it can be easily retrofitted to an existing large volume sprinkler in the field. On present large volume, part circle sprinklers, there is a fixed “trip lever” or lever arm that operates between two stops that determines the arc of travel through which the sprinkler will rotate. In the exemplary embodiment of the invention, the lever arm is adjustable, and by selectively positioning the lever arm such that it works on different stops, the arc of travel of the sprinkler can be changed. The arc changer in accordance with the exemplary embodiment utilizes two hydraulic cylinders (an upper cylinder and a lower cylinder) to move the trip lever between three positions of operation.  
           [0006]    More specifically, the trip lever is pivotally mounted to a hub, with a pair of links pivotally mounted at one end on the lever, on opposite sides of the trip lever pivot. Each of the pair of links is attached at opposite ends to pistons slidably supported in the hub for axial movement within hydraulic chambers or cylinders. Depending on which of the pistons is actuated, the trip lever is caused to swing inwardly or outwardly on its own pivot. Thus, the remote end of the lever is moved radially outwardly to a first position when hydraulic fluid is supplied to the lower chamber. The lever is moved radially inwardly to a third position when hydraulic fluid is supplied to the upper chamber. When neither chamber is pressurized, the lever is balanced by springs in an intermediate or second position, radially between the first and third positions.  
           [0007]    The stops are designed such that their outside radii are shaped like arcuate cams that correspond to the first, second and third positions of the lever arm. In this regard, the remote end of the lever arm is fitted with a cam roller. During normal rotation through an arc of travel, the cam roller moves through its arc without engaging the adjacent cam surface. However, when the arc changer is actuated to move the lever arm to another position when the sprinkler is in a position that is not already in the range of the new stop set, the roller on the end of the trip lever arm will be forced onto the cam surface of the stop. The sprinkler will continue to operate with the trip lever roller, rolling along the cam surface until it falls within the operating zone, i.e., within the circumferential arc, of the new particular set of stops. If the sprinkler is transitioned into the next set of stops when the lever arm is circumferentially within the arc of the next set of stops, it will change arcs without the roller contacting any of the arc shaped cam surfaces.  
           [0008]    As described herein, the sprinkler uses hydraulic cylinders or chambers using water as the working fluid. These cylinders could also be pneumatic, oil hydraulic, or electromechanical. The input for changing the arc may be conventional timers, remote control or hardwired signals operating solenoids or other forms of control valves. The adjustable stops may be made by providing the cams on plates arranged to slide under and/or over each other, thus allowing greater range of arc variation. This allows the end user to easily adjust the sprinkler to their specific application.  
           [0009]    According to one aspect, the present invention relates to an actuator assembly for a rotatable sprinkler head having a base supported for rotation on a stationary platform assembly, the actuator assembly comprising a hub mounted for rotation on a shaft supported in said base; a lever arm pivotally mounted at one end to said hub and having a free end extending downwardly toward a stop plate assembly supported on said platform assembly; said stop plate assembly configured to define two or more arcuate paths of travel for said lever arm, said paths being radially offset relative to said hub; and wherein said lever arm is adjustable to selectively locate said free end in any of said two or more arcuate paths of travel.  
           [0010]    In another aspect, the invention relates to an actuator assembly for a large volume sprinkler head mounted for rotation relative to a stop plate assembly, the actuator assembly comprising a lever arm on the sprinkler head adapted to cooperate with the stop plate assembly to define different paths of travel for the sprinkler head; the lever arm movable radially between the different paths of travel.  
           [0011]    The invention will now be described in greater detail in connection with the various drawing figures identified below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a side elevation of a large volume part circle sprinkler head and arc changer mechanism in accordance with an exemplary embodiment of the invention;  
         [0013]    [0013]FIG. 2 is a plan view of the sprinkler head shown in FIG. 1, with the barrel of the sprinkler head rotated to a horizontal plane;  
         [0014]    [0014]FIG. 3 is a plan view of the arc changer mechanism, with the sprinkler barrel removed;  
         [0015]    [0015]FIG. 4 is a side elevation, partly in section, showing the lever arm in a first outer operative position;  
         [0016]    [0016]FIG. 5 is a side elevation, partly in section, showing the lever arm in a second intermediate operating position;  
         [0017]    [0017]FIG. 6 is a side elevation, partly in section, showing the lever arm in a third inner operating position;  
         [0018]    [0018]FIG. 7 is a plan view of a stop ring and stop plates taken from FIGS.  1 - 3 ;  
         [0019]    [0019]FIG. 8 is a detail taken from FIG. 7;  
         [0020]    [0020]FIG. 9 is a plan view of a modified stop arrangement;  
         [0021]    [0021]FIG. 10 is a diagram of a field showing different arcs of travel based on the stops arranged as shown in FIG. 7 in the context of a traveler-type sprinkler; and  
         [0022]    [0022]FIG. 11 is a diagram of a field showing different arcs of travel based on the stops arranged as shown in FIG. 9. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    With reference to FIG. 1, there is shown a sprinkler head  10  that includes a stationary annular platform assembly  12  adapted to be fixedly mounted at its lower portion on a source pipe or the like (shown in dotted line configuration at  15 ) for supplying water to the sprinkler head under pressure. Mounted on the platform assembly for rotational movement about a fixed vertical axis A, coincident with the vertical axis of the platform assembly, is a rotating sprinkler body assembly generally indicated at  14 . The platform assembly  12  incorporates a brake and bearing arrangement (not shown) that serves to mount the sprinkler body assembly on the annular platform assembly  12  for controlled rotational movement in clockwise or counterclockwise directions. That portion of the platform assembly that receives the sprinkler body assembly  14 , as well as the sprinkler body assembly itself, is preferably constructed in accordance with commonly owned U.S. Pat. No. 4,720,045, incorporated herein by reference.  
         [0024]    The sprinkler body assembly  14  includes an elbow or base  16  having an elongated barrel  18  fixed thereto. At the outlet end of the barrel  18 , there is secured a nozzle  20  serving to direct a stream of water in an upwardly and outwardly direction. Mounted on the barrel  18  for pivotal movement about an axis substantially perpendicular to the longitudinal axis B of the barrel  18  is a yoke  22  that moves between first and second operating positions. The yoke  22  serves to mount an impulse arm assembly  24  for movement with the yoke into two corresponding operating positions and for oscillating movements about a transversely extending oscillatory axis D. Note that axis D is disposed above the longitudinal axis B of the barrel  18  and in a position outwardly of the pivot axis C of the yoke and impulse arm assembly in the downstream direction.  
         [0025]    The impulse arm assembly  24  has mounted on its outward end a drive spoon generally indicated at  26 . The drive spoon is operable in either of the two operating positions of the yoke or impulse arm assembly and functions to effect continuous oscillatory cycles of the impulse arm assembly  24 , during each one of which, the drive spoon  26  is moved into a position of engagement with the stream issuing from the nozzle. The detailed construction and operation of the sprinkler head per se, including the yoke, impulse arm assembly and spoon assembly are well known as described in the above-identified commonly owned patents. The sprinkler head may also be one that is currently available from the assignee, Nelson Irrigation Corp., under the name “SR 150 Big Gun.” In addition, the manner in which the sprinkler head rotates in step-wise fashion and reverses direction is also well known as described in the above-identified patents, and need not be described in detail here. This invention relates specifically to an arc changer mechanism for use with the sprinkler head.  
         [0026]    The actuator assembly includes a hub  34  mounted for rotation in the elbow  16  via a shaft  30 . The actuator assembly also includes a bifurcated lever arm  29  that cooperates with a tube  31  that form part of an overcenter resilient toggle mechanism that facilitates the oscillating motion of the sprinkler. This action is fully described in the &#39;045 patent.  
         [0027]    With reference particularly to FIGS. 1, 2 and  4 , the lever arm  32  in the exemplary embodiment is pivotally mounted at one end to the housing  36  and hub  34  by means of a fixed link  38  and pivot pin  40 . The lever arm  32  is provided at its opposite end with a cam roller  42 . Movement about the pivot pin  40  is controlled by a pair of links  44 ,  46  that are pivotally mounted to the lever arm, on either side of link  38 , by respective pivot pins  48  and  50 . The upper link  44  is, in turn, pivotally connected to a rod  52  fixed for sliding movement inside the housing  36 . Rod  52  is attached to one end of a piston rod  54 , an associated piston head  56  slidable within cylinder or chamber  58 . Chamber  58  is supplied with working fluid (water, in the exemplary embodiment) via passage  60  in the hub  34 .  
         [0028]    The lower link  46  is similarly pivotally connected to a second rod  62  via pivot pin  64 . Rod  62  is also confined to sliding movement in the housing  36  and is attached to a second piston rod  66 . Piston head  68  is slidable within a second cylinder chamber  70  that is supplied with working fluid via passage  72 .  
         [0029]    The cam roller  42  at the remote end of the lever arm  32  is shown in its upper or radially outermost position in FIG. 4, as a result of water under pressure being supplied to the second chamber  70 . This causes piston  66  and rod  62  to push lower link  46  to the left, at the same time pushing the lever arm  32  in a clockwise direction about the pivot pin  40 . Note that the absence of water pressure in the first chamber  58  permits the rod  52  and link  44  to move to the right to accommodate the clockwise movement of the lever arm  32 .  
         [0030]    [0030]FIG. 5 illustrates the lever arm  32  in an intermediate position, as a result of balanced return springs  74 ,  76 , acting on the respective pistons with no water pressure in either of chambers  58  or  70 .  
         [0031]    [0031]FIG. 6 illustrates the lever arm  32  in a radially inner and lower position, caused by the supply of water under pressure to the first chamber  58 . This pushes piston  54 , rod  52  and link  44  to the left, resulting in counterclockwise rotation of the lever arm  32  about the pivot pin  40 . The lack of any water pressure in the second chamber  70  permits the link  46  to push the rod  62  and piston  66  to the right. as viewed in the Figure.  
         [0032]    With reference now to FIGS. 3 and 7, the platform assembly also includes an outer stop ring  78  that is supported by three circumferentially spaced, generally U-shaped struts  80 ,  82  and  84  that extend substantially radially between the outer stop ring  78  and a stop plate  86  concentrically located relative to a pipe inlet flange of elbow  16 . Stop plate  86  is located below, but parallel to the outer stop ring  78 . Edges  88  and  90  of the outer stop ring  78  define the limits of a first path of approximately 180° for the lever arm  32 , the lever path indicated by LP 1  in FIG. 7. This path will be followed by the lever arm when it is in its extended position, shown in FIG. 4. This path provides the sprinkling pattern designated SP 1  in FIG. 10.  
         [0033]    A second path LP 2  extends between intermediate edges  92 ,  94  of the stop plate  86  and corresponds to the sprinkling pattern SP 2  in FIG. 10.  
         [0034]    A third path LP 3  extends between inner edges  96 ,  98  of the stop plate  86  and corresponds to the sprinkling pattern SP 3  in FIG. 10.  
         [0035]    During a normal sequence of reversing action with the lever arm  32  in the extended position (FIG. 4) in path LP 1 , the cam roller will not engage the camming surface  92  on the stop plate  86 , but will remain radially spaced therefrom as indicated in phantom in FIG. 7, to produce the pattern SP 1  in FIG. 10 Note in FIG. 10 that the sprinkler cart is shown at  87 , the hose at  89  and the hose reel at  91 .  
         [0036]    When the arc changing mechanism actuator is actuated to move the lever arm  32  to its intermediate position shown in FIG. 5, so as to begin following path LP 2 , the cam roller  32  may be within the arcuate range of LP 2  or outside the range of LP 2 . Note that the part of LP 1  that is outside the range of LP 2  corresponds to the arcuate extent of camming surface  100  on the plate  86 . If the lever arm  32  is within the arcuate extent of camming surface  100  when the arc changer is actuated to move it from LP 1  to LP 2 , the roller will be drawn into engagement with surface  100  (see FIG. 8) as the lever arm  32  pivots inwardly about pivot  40 . When the roller reaches edge  94 , it will fall into the second path LP 2  (but it will not engage the inner camming surface  102 ). If, on the other hand, the lever arm  32  is within the range of LP 2 , i.e., beyond camming surface  100 , it will simply fall into LP 2 . Note this description assumes clockwise movement of the lever arm  32 . The same action will occur in the opposite direction as well.  
         [0037]    As the lever arm oscillates between stops or edges  92 ,  94  in LP 2 , creating the pattern SP 2  in FIG. 10, the roller  42  will not engage camming surface  102  nor the opposite camming surface  104  at the other end of the arc of travel in LP 2 .  
         [0038]    When the arc changer is actuated to move the lever arm  32  into LP 3 , the lever arm may again be inside or outside the range of LP 3 . If outside the range, the roller  42  will be caused to engage camming surface  102  (or  104 ) until it reaches edge  98  (or  96 ) where it will fall into the path LP 3  in the same manner as described above in connection with the transition from LP 1  to LP 2 . In LP 3 , the lever arm will oscillate between stop edges  96 ,  98  to create the pattern SP 3  in FIG. 10.  
         [0039]    While the outer ring  78  and stop plate  86  have been described as fixed in a rigid configuration, other arrangements are contemplated. The outer ring  78  and stop plate  86  may be made rotationally adjustable, and one or more stops may be added. In FIG. 9, for example, two additional stops  106 ,  108  have been added. Stop  106  will reduce LP 1  to a 90° arc of travel, corresponding to SP 4  in FIG. 11. Stop  108  will reduce LP 2  to a 135° arc of travel corresponding to SP 5  in FIG. 11, and stop  108  will also reduce LP 3  to a 90° arc of travel corresponding to SP 6  in FIG. 11. This arrangement is particularly useful when irrigating next to a fence, building or the like located along the side of the field or lot.  
         [0040]    A similar stop plate assembly with different stop sets can be used when the sprinkler is employed as an end gun in a pivot system. The end gun can be turned on and off, with different arcs of travel, as the pivot boom moves into, through and out of the corner area, causing more of the field to be irrigated.  
         [0041]    It will also be appreciated that the stop plate  86  may be constructed in two or more sections (indicated by the dotted lines  110 ,  112  in FIG. 7), with one plate section sliding above or below the other to provide greater flexibility in setting up different arcuate paths for the sprinkler head.  
         [0042]    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.