Abstract:
A swivelling fan-jet sprinkler which is convertible from a coarse sprinkling mode in which it covers a relatively large irrigation area to a gentler spraying mode in which it covers a smaller area, the conversion being achieved by means of a removable spinner cage which surrounds the nozzle cylinder of the sprinkler. The spinner cage has a captive snap ring cooperating with a groove in the nozzle cylinder to produce a detent action for attachment and removal of the spinner cage. The latter is driven by the water jets which are disturbed in the process.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to irrigation sprinklers and, more particularly, to a swivelling fan-jet sprinkler of the type which has a slowly swivelling horizontal nozzle cylinder with a row of jet nozzles arranged in a fantail pattern, including means for adjusting the action of the sprinkler for the coarse sprinkling of a large area or the gentler spraying of a smaller area. 
     2. Description of the Prior Art 
     Swivelling sprinklers of the above-mentioned type are known from the prior art. They are being used for the watering of lawns as well as the irrigation of vegetable and flower beds, having the advantageous capability of covering an area of square or rectangular outline. However, the size of the drops and the intensity of the water jets which are optimal for one application are generally not optimal for the other. Lawns, for example, are much less sensitive to the size of the water drops than most vegetables and flowers, and they will tolerate relatively large drops without damage. The intensity and size of the water jets, on the other hand, determine the length of the trajectory of the water drops and, consequently, the size of the area covered. At the same water pressure, large drops have a longer trajectory than small drops. 
     It has therefore already been suggested to provide such a swivelling fan-jet sprinkler with a means for adjusting the water jets at the nozzle cylinder. Such a device is disclosed in the German Pat. No. 19 26 735 which describes a sprinkler with an angularly adjustable control sleeve arranged on the inside of its nozzle cylinder and held in place by friction. The angular position of the control sleeve determines the degree to which the openings of the nozzle bores are obstructed and the intensity of the water jets is reduced. The result is a corresponding reduction in the size of the area covered. It includes the possibility of atomizing the water jets, in which case the droplet trajectory is very much shortened. It has been found, however, that atomization of the water is not necessary, even for the most delicate of cultivated plants. 
     SUMMARY OF THE INVENTION 
     Underlying the present invention is the objective of developing an improved sprinkler of the type which is selectively adjustable to a sprinkling mode with high jet intensity and maximum area coverage which is optimal for lawn watering, and to a spraying mode with reduced drop size which is optimal for the irrigation of delicate cultured plants. 
     The present invention is attaining this objective by suggesting a novel sprinkler which includes a removable spinner cage on the nozzle cylinder and which performs in a high-powered lawn sprinkling mode without the spinner cage and in a comparatively gentle plant spraying mode with the spinner cage in place. 
     In a preferred embodiment of the invention, the spinner cage has a bore engaging the outer diameter of the nozzle cylinder with rotational clearance and a snap ring engaging a groove of the nozzle cylinder. The snap ring and the groove are so arranged that the spinner cage can be attached and removed with a simple snap action. The snap ring is preferably captive on the spinner cage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further special features and advantages of the invention will become apparent from the description following below, when taken together with the accompanying drawings which illustrate, by way of example, an embodiment of the invention which is represented in the various figures as follows: 
     FIG. 1 shows a swivelling sprinkler in accordance with the invention in an elevational side view, the major portion of the fan-jet nozzle cylinder being shown in cross section and the spinner cage having been removed for operation in a high-powered lawn sprinkling mode; 
     FIG. 2 shows a spinner cage, designed for attachment to the nozzle cylinder of FIG. 1; 
     FIG. 3 is a transverse cross section through the spinner cage of FIG. 2, taken along line III--III thereof; 
     FIG. 4 shows a flexible snap ring for the axial positioning of the spinner cage on the nozzle cylinder; 
     FIG. 5 shows the swivelling sprinkler of FIG. 1 with the spinner cage of FIG. 2 in place, for operation in a gentle plant spraying mode; 
     FIG. 6 is an enlarged transverse cross section through the assembly of FIG. 5, taken along line VI--VI thereof; and 
     FIG. 7 is a similarly enlarged transverse cross section through the assembly of FIG. 5, taken along line VII--VII thereof. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As can be seen in FIG. 1, the swivelling sprinkler of the invention comprises a sprinkler stand 10, a sprinkler housing 11 carried by the stand 10, and a nozzle cylinder 13 extending horizontally from the housing 11. A garden hose (not shown) supplies water to the sprinkler housing 11 through a hose connector 12 on the lower rear side of the housing 11. 
     Inside the sprinkler housing 11 is arranged a known sprinkler drive which includes a turbine wheel, a high-ratio gear transmission, and a forwardly protruding crankshaft 17. The flowing water, by rotating the turbine wheel, slowly rotates the crankshaft 17, thereby driving a crank 18 whose distal extremity is connected in a known way to a radially extending drive arm 13a of the nozzle cylinder 13. 
     The nozzle cylinder 13 has its rear extremity rotatably supported by the sprinkler housing 11, so that the cylinder extends forwardly in a cantilever fashion, while executing a slow swivelling movement about its horizontal axis of rotation b--b. The nozzle cylinder 13 has arranged on its upper side a row of nozzle bores 15 which are oriented in a diverging pattern, successive bores being progressively more inclined in relation to a central radial line. The result is a fantail-shaped curtain of water jets 16 which slowly swivel back and forth, covering a rectangular area. 
     The nozzle cylinder 13 has its forward extremity closed off by means of a rounded cylinder cap 14. The diameter of the cap 14 matches the diameter of the cylinder 13. Rearwardly of its row of nozzle bores 15, the nozzle cylinder 13 continues in a cylinder portion of the same diameter which has arranged in it an annular groove 19. The sprinkler of FIG. 1, is set for operation in the lawn sprinkling mode, i.e. a high-power mode in which the water jets 16 exit from the nozzle cylinder 13 without obstruction, thus covering a large area. 
     In FIG. 5, the sprinkler of FIG. 1 is shown to carry on its nozzle cylinder 13 a spinner cage 20, held in place by a snap ring 21 which engages the annular groove 19 of the cylinder 13. The spinner cage 20 is shown in FIGS. 2 and 3 and the snap ring 21 is shown in FIG. 4. 
     As can be seen in the enlarged cross section of FIG. 6, the spinner cage 20 surrounds the nozzle cylinder 13 with a rotational gap 23a, the inner diameter 20c of the cage 20 being slightly larger than the outer diameter of the cylinder 13. 
     The spinner cage 20 has a through-bore 20c and, on its rear extremity, a shoulder extension 20a of reduced diameter (FIG. 2). At the base of the shoulder extension 20a are two diametrally opposite chord grooves 23 intersecting the bore 20c, as shown in FIG. 3. Into the chord grooves 23 fit the parallel chord edges 22 of the snap ring 21. This ring is sufficiently flexible to be inserted over the shoulder extension 20a by forcing its chord edges 22 apart. After insertion, the snap ring 21 remains captive on the spinner cage 20. 
     As can be seen in FIG. 7, the distance between the chord edges 22 of the snap ring 21 is less than the diameter of the nozzle cylinder 13. This means that, when the spinner cage 20 is inserted over the cylinder 13, the chord edges 22 are forcibly held apart, as they slide along the surface of the cylinder 13, until they snap into its annular groove 19. The diameter of the base 19a of the groove 19 is preferably smaller than the distance between the chord edges 22 of the snap ring 21, and the width of the latter allows for a lateral clearance in the groove 19, so that the spinner cage 20 rotates freely on the nozzle cylinder 13, while being held in place in the axial sense. 
     FIG. 1 shows that the flank of the groove 19 on the side of the nozzle bores 15 is slightly rounded so that, by pulling the spinner cage 20 forwardly, the chord edges 22 of the snap ring 21 are again forced apart, onto the outer surface of the nozzle cylinder 13. The spinner cage 20 can thus be removed with a simple pulling action. The hemispherical shape of the cylinder cap 14 produces a similar opening effect on the snap ring 21, when the spinner cage 20 is inserted over the nozzle cylinder 13. Accordingly, both the attachment and the removal of the spinner cage involve extremely simple snap action operations. 
     Of course, it is also possible to insert the spinner cage 20 in such a way that its snap ring 21 is on the forward side of the nozzle cylinder 13. In this case the annular groove can be conveniently arranged between opposing flanks of the nozzle cylinder 13 and the cylinder cap 14. 
     Referring to FIGS. 2 and 6, it can be seen that the spinner cage 20 has on its circumference a series of longitudinal slots 24 which form webs 20b between them. The webs 20b are wedge-shaped, having pointed edges facing inwardly against the nozzle cylinder 13, thereby presenting only a negligible obstruction to the water jets, as they exit from the nozzle bores 15. The slots 24 extend over almost the entire length of the spinner cage 20, leaving short slot-free bore portions on both extremeties for rotational support on the nozzle cylinder 13. These short bore portions may have a lesser clearance to the nozzle cylinder than the rotational gap 23a of FIG. 6. 
     As is shown in FIG. 6, the slots 24 are inclined in relation to a radial plane, so that the water jets which exit radially from the nozzle bores 15 impinge on the inwardly exposed flank of each slot 24, thereby driving the spinner cage 20 in the manner of a turbine wheel. As an alternative to the inclined slots 24, it is also possible to incline the nozzle bores 15, in order to obtain a similar turbine effect. 
     As the exiting water jets impinge on the flanks of the slots 24 of the spinner cage 20, they are slightly deflected and thereby disturbed just enough to reduce the drop size as desired. The geometric shape of the area covered remains unchanged, being somewhat smaller in size, however, due to a small loss in kinetic energy of the water jets and a higher relative air resistance acting on the smaller drops. By thus adding the spinner cage 20 to the sprinkler of FIG. 1, the latter operates in a plant watering mode, i.e. a gentler spraying mode. 
     It should be understood, of course, that the foregoing disclosure describes only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of this example of the invention which fall within the scope of the appended claims.