Pressure activated conical spray nozzle
BACKGROUND OF THE INVENTION 
     This invention relates to liquid spray nozzles and, in particular, to nozzles of the type used for generating fine droplet, conical sprays such as utilized in fire control spray systems as used on flight decks of naval aircraft carriers. 
     More particularly, nozzles of the type embodying this invention are pressure activated so that when liquid under pressure is supplied to the inlet opening, a spray generating helical component within the nozzle is automatically extended to its operating position. 
     Pressure responsive fluid nozzles have been heretofore disclosed in the prior art for various purposes, including fuel injection nozzles for internal combustion engines and atomizing nozzles. U.S. Patents disclosing such nozzles includes Nos. 1,833,748; 1,879,012; 2,338,744; 3,801,021 and 4,394,972. While these patents relate to pressure activated spray nozzles, they do not disclose any nozzle which includes a helical vane adapted by axial movement thereof to be extended from the nozzle body to generate a fine droplet, conical spray uniquely adapted for fire fighting purposes. 
     In a prior U.S. Pat. No. 4,456,181 assigned to the same assignee of the instant application, a gas and liquid mixing nozzle is disclosed for an abrasive type slurry which includes a stationary helical insert constructed to form a conical spray adapted for use in stack gas scrubber applications. 
     It is the principal object of this invention to provide an improved conical spray nozzle which includes a reciprocably movable spray generating element which is extendable to its spray generating position in response to the fluid input pressure of the liquid to be sprayed. 
     It is another object of this invention to provide an improved conical spray nozzle uniquely adapted to be used in fire fighting applications on the flight deck of aircraft carriers and similar installations. 
     It is a further object of this invention to provide a conical spray nozzle in which a liquid carrying conduit is axially movable within the nozzle. 
    
    
     The above and other objects and advantages of this invention will be more fully appreciated by a reading of the following description in conjunction with the accompanying drawing in which: 
     FIG. 1 is an elevational view, partly in cross-section, of a spray nozzle of the type embodying this invention, and 
     FIG. 2 is an end view showing the inlet end of the nozzle as shown in FIG. 1. 
    
    
     Referring in detail to the drawing, in FIG. 1 is shown a spray nozzle indicated generally at 4. The nozzle includes an inlet opening or port 6 for liquid at one end and a liquid discharge opening 8 at the opposite end of the nozzle. 
     An internally threaded coupling or end plate fitting 10 is screw-fitted into one end of an outer sleeve or tubular barrel 12 of the nozzle. A sealing ring 14 is provided to ensure a fluid tight seal between the end plate 10 and the nozzle barrel 12. 
     The barrel 12 of the nozzle is of generally cylindrical construction and has a radially stepped tubular construction with its largest diameter disposed toward the inlet port 6 and its smallest diameter disposed toward the outlet end of the nozzle. The barrel 12 terminates at end wall 16 in spaced relation to a bulkhead represented at 18. By simply rotating the nozzle axis and bulkhead 90 degrees, the nozzle would be adapted for installations in the deck 18 of a vessel, such as a naval aircraft carrier. The nozzle includes tubular sheath 20 which extends through an opening 22 provided through bulkhead or deck 18. The nozzle may be affixed to the deck, such as by welding as shown at 23. 
     The sheath 20 has its inner end screw-fitted, as at 24, into the inner end of the barrel 12 and in effect, the sheath and barrel provide the fixed outer barrel structure of the nozzle. Radially extending set-screws 27 securely fasten the sheath 20 and barrel 12 in end-to-end relationship. This separable outer barrel nozzle construction greatly facilitates initial installation and disassembly of such nozzle for repair or replacement. The outer end of the sheath includes an enlarged bead or rim 26 of flared configuration. 
     Coaxially disposed within the outer barrel portions of the nozzle is a tubular conduit 30 and a tubular spray element 32 fastened together in end-to-end relationship as by a threaded connection illustrated at 34, thereby providing a continuous passage or conduit for liquid from the inlet opening 6 to the discharge opening 8 of the nozzle. 
     An annular flange 36 is carried on one end of the tubular conduit 30 and an O-ring 38 provides a fluid tight seal between the inner wall of the barrel 12 and the peripheral edge of the flange 36. The flange 36 serves as a piston for causing axial movement of the tubular conduit members 30 and 32 in response to the fluid pressure of liquid entering the inlet opening 6. The inner diameter of conduit 30 is relatively larger, on the order of 5/8&#34; so that high volume liquid flow will be supplied to the helical spray member. The bore of conduit 32 is tapered inwardly to a substantially smaller inner diameter. 
     A coil spring 40 is fitted about the conduit 30 and has one end disposed against the inner surface of flange 36 and its opposite end engaged with radial shoulder 42 within the barrel 12. The spring releasably urges the piston toward the inlet opening of the nozzle. The upstream surface area of the piston 36 and the compression strength of spring 40 are selected so that a fluid inlet pressure of about 8-12 pounds per square inch will cause the piston to compress the spring fully to its dotted line position of FIG. 1 when the piston contacts shoulder 41 within the barrel 12. 
     The inner annular chamber 43 of the barrel portion of the nozzle surrounding the conduit formed by tubular elements 30 and 32 is separated longitudinally into liquid and air filled chambers of varying volume defined by the longitudinal position of piston element 36. It should be realized that the air chamber containing the spring 40 must not be made airtight so that as the piston 36 is moved by fluid pressure compressing spring 40, air will be allowed to bleed from the barrel so that the air in chamber 43 will not be compressed. 
     Adjacent the discharge end of the nozzle, the liquid conduit formed by the tubular members 30 and 32 includes a helically extending opening 46 formed in the outer end portion of the spray member 32. As shown, the helical opening 46 extends into the bore 44 of the conduit for approximately one complete turn of 360 degrees from its inner to outer end. The pitch of the helix may vary but a pitch from one to four turns per inch axially of the nozzle has resulted in suitable spray generation for purposes of this invention. The inner bore 44 of the spray member has a gradually tapered diameter from its inner to its outer end whereby, at the helical cutout section of the spray, the wall thickness is of gradually increasing thickness. The taper of bore 44 restricts the flow of liquid from larger inner bore 30 and thus helps in maintaining sufficient fluid pressure on piston 36 to hold the nozzle &#34;open.&#34; The upstream surface defined by helical cutout 46, in effect, provides a helical vane having generally planar surfaces facing the upstream end of the nozzle so that liquid striking the helical vane surface will be deflected outwardly into a fine droplet, generally conical spray which is approximately symmetrical about the axis of the nozzle. 
     The outer end of spray forming element 32 includes a transverse flange 48 generally perpendicular to the nozzle axis. The flange 48 serves as an end cap, cover or closure member for the nozzle which is dimensioned so that its peripheral edge will fit within annular recess 50 provided at the corner edge portion of the enlarged bead 26 of sheath 20. When the nozzle is not in operation, spring 40 will force the flange 36 to its retracted position and flange 48 will fit snugly within recess 50 in generally coplanar relationship with the outer surface of the deck or bulkhead 18 so as not to interfere with the normal flight deck traffic. 
     When water, under sufficient fluid pressure, is introduced into the nozzle at inlet port 6, the pressure on the upstream face of piston 36 will cause the piston 36 to move, compressing spring 40 to the dotted line showing of FIG. 1. The longitudinal stroke of the piston 36 is of sufficient length so that the helical vane portion of the conduit will be disposed outwardly of the outer surface of deck 18, as illustrated in the dotted line showing at FIG. 1. The water flowing through conduit 30 and tapered bore 44 will flare outwardly at the helical opening 46 striking the upstream surfaces of the helical vane to form a fine droplet but high volume of conical spray.