Air assisted atomizing spray nozzle

Abstract: An air assisted atomizing spray nozzle including an atomizing member (33) having: (a) a mixing chamber (42), (b) a liquid inlet opening (39) for injecting a liquid stream axially into the mixing chamber, (c) a pair of air inlet openings (41a, 41b) for injecting a pair of air streams radially into the mixing chamber in directions substantially opposed to one another and substantially perpendicular to the liquid stream for atomizing the liquid stream, and (d) an exit orifice (44) in axial communication with the mixing chamber for discharging atomized liquid therefrom. The atomized liquid is sprayed into atmosphere by a spray tip (34). The atomizing member (33) and the spray tip (34) are held in assembled relation with a housing (32) by a quick connect/quick release cap (35).

Description: Technical Field This invention is related generally to nozzles for spraying liquids, and more particularly, to improved air assisted atomizing spray nozzles. Background of the Invention There are many different types of nozzles for spraying liquids. One type is a so-called air assisted atomizing spray nozzle. Such nozzles are capable of delivering a liquid in a finely divided, or atomized state. Atomization of a liquid in this type of nozzle is assisted by introducing air into the nozzle. More specifically, a liquid stream and an air stream are injected into a mixing chamber. The interaction of the air and liquid stream, among other factors, atomizes the liquid stream for discharge through an exit orifice of the nozzle. Air assisted atomizing spray nozzles are used to apply agricultural chemicals and in other applications, such as pest control, where it is important to achieve a uniform distribution of relatively small amounts of chemicals. They also are used in humidifying systems to assure rapid evaporation of water into the atmosphere. Another use is in scrubbing systems for coal furnaces where rapid and complete chemical absorption of sulfurous gases must be optimized. In general, this type of nozzle is used in a wide variety of applications where it is important to deliver liquid in a finely atomized state. One design for air assisted atomizing spray nozzles is shown in United States Patent 5,082,185 to W. Evans. The nozzle shown therein is used with a hand-held spray gun which is particularly useful for applying pesticides. The air source for the gun can be either a high pressure tank or a tank which is pressurized by a hand pump. The design of the spray gun offers significant advantages, especially in that it reduces liquid leakage during shut-off. Nevertheless, the nozzle assembly shown in the above-mentioned Evans patent has room for improvement in several respects. First, certain components of the nozzle are relatively fragile, in particular, the parts that define the mixing chamber 15 shown in FIG. 2 of the Evans patent. The spraying equipment with which the nozzle is used typically is carried from location to location. It also is carried by hand as pesticide is applied at a particular location. Under such circumstances, and even during assembly and repair of the nozzle, the perforated annular disk-shaped structure at the downstream end of the mixing chamber 15, may be bent or broken. Such damage, of course, can interrupt or diminish the performance of the spray nozzle. Although durability may be less important if the nozzle is a component of a system which is more or less permanently installed, there are other problems with the design of the nozzle shown in the Evans patent. Nozzle parts very commonly are manufactured from cast or machined metal plugs, such as brass or stainless steel, which then are drilled or milled to provide the various openings and cavities. There are, however, a number of close-tolerance drillings which must be performed in order to form the mixing chamber 15 illustrated in the Evans patent. Consequently, manufacturing parts is relatively difficult and costly, and there are relatively high rejection rates during the manufacturing process. In certain applications, a spray nozzle will be used to spray highly abrasive liquids, such as limestone slurries in a smoke stack scrubbing system. Under such conditions, the mixing chamber parts are subject to considerable wear. It is possible to increase the wear resistance of nozzle parts by using more wear resistant compositions, such as ceramics, but such materials must be cast or molded and cannot be readily machined. The mixing chamber part of the Evans patent, as a practical matter, cannot be adapted for use in high wear applications because the relatively complex design does not lend itself easily to casting or molding processes. Moreover, it generally is desirable to minimize the quantity of air used to achieve a given degree of atomization of a given quantity of liquid. Improved air efficiency can permit the use of less expensive, lower capacity equipment and can lower operating costs in many systems. Air efficiency is especially important in equipment, such as that shown in the Evans patent, which relies on a portable air source. For example, the life span of high pressure tanks decreases as air consumption increases, and tanks have to be changed more frequently. If a hand pumped tank is used, work must be interrupted more frequently so that the tank can be pumped up. The atomization process in this type of spray nozzle also is relatively inefficient because it relies on what may be called "parallel flow" of liquid and air. As can be seen best in the front elevational view of part 15 of the Evans patent, which view is shown in FIG. 2 and labeled 15a, the air streams and liquid streams are introduced into the mixing chamber parallel to each other. In other words, the liquid stream is introduced through the center aperture in part 15, and air is introduced through the four apertures radially disposed from the center hole but opening parallel to it. One general approach to increasing the efficiency of the atomization process in mixing chambers has been to provide so-called impingement surfaces. Air assisted atomizing spray nozzles comprising impingement surfaces are shown, eg., in United States Patent 4, 899, 937 to J. Haruch, United States Patent 4, 815, 665 to J. Haruch, and United States Patent 4, 349, 156 to J. Haruch. In general, these types of designs inject a liquid stream and an air stream into a mixing chamber perpendicular to each other with an impingement surface being situated at or near the point where the streams intersect. While this can create considerable turbulence, thereby improving the atomization process, the nozzle is more complex because it incorporates impingement surfaces. Generally, additional parts must be fabricated in order to provide an impingement surface. The relative alignment of the air inlet, liquid inlet, and impingement surface also must be relatively precisely controlled. As a consequence, it is more difficult and costly to manufacture nozzles of this type. We are aware of WO-A-93/20948 which forms the precharacterising portion of claim 1. In WO-A-93/20948 an externally threaded lock screw is adapted to secure the atomizing member upstream of the spray tip. According to our invention an air assisted atomizing nozzle assembly comprises a housing having a pressurized liquid inlet and a pressurised air inlet, an atomizing member defining (i) a mixing chamber having a longitudinal axis, (ii) a liquid injection port in axial communication with said mixing chamber for injecting a liquid stream axially into said mixing chamber, and (iii) a plurality of air injection ports in radial communication with said mixing chamber for injecting a plurality of air streams radially into said mixing chamber thereby to atomize said liquid stream, a spray tip located downstream of said mixing chamber for spraying the atomized liquid into the atmosphere, and means for holding said spray tip and said atomizing member in assembled relation with said housing with said spray tip in communication with said mixing chamber and with said liquid injection port and said air injection ports in communication with said air inlet and said liquid inlet respectively, said means comprising a cap engageable with at least one of said spray tip and said atomizing member, characterized by co-acting means on said cap and said housing permitting a portion of said cap to be inserted linearly into said housing without turning said cap relative to said housing, and said co-acting means being operable after insertion of said cap portion into said housing and after said cap has been rotated through less than one full turn relative to said housing to lock said cap to said housing and to cause said cap to hold said spray tip and said atomizing member in fixed relation with said housing. We are therefore able to provide as air assisted atomizing spray nozzle which is more durable in use and is less susceptible to bending or breaking, and is more easily and reliably manufactured. Conveniently most of the components of the nozzle may be made by an injection molding process. The air assisted atomizing spray nozzle atomizes liquid more efficiently, thereby reducing the amount of air consumed. The air assisted atomizing nozzle assembly may be quickly and easily assembled and disassembled and may be converted for use with different types of spray tips and/or atomizers. The foregoing objects and advantages of the invention will be apparent to those skilled in the art upon reading the following detailed description and upon reference to the drawings. Brief Description of the Drawings Fig. 1 is a side view, partially in section, of a preferred embodiment of the novel air assisted atomizing spray nozzle; Fig. 2 is an exploded perspective view of the nozzle shown in Fig. 1; Fig. 3 is a fragmentary cross-section taken substantially along the line 3-3 of Fig. 1; Fig. 4 is a view similar to Fig. 3 but shows certain components in moved positions; and Fig. 5 is a fragmentary cross-section taken substantially along the line 5-5 of Fig. 4. While the invention is susceptible of various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention. Description of the Preferred Embodiments Referring now to the accompanying drawings there is shown a nozzle assembly in accordance with the present invention, for a hand-held spray gun. This spray gun is constructed, except for incorporating the novel nozzle, substantially as described in the Evans patent discussed above. Accordingly, the text of that patent is incorporated in its entirety by this reference thereto. The gun basically comprises three subassemblies: a handle assembly, a wand assembly, and a nozzle assembly 85. The handle assembly is provided with a pressurized liquid inlet adapted to connect, through a hose (not shown) with an external pressurized liquid reservoir (not shown). Liquid flows through a passageway in the handle assembly and is controlled by valve means which is actuated by a handle. When the valve means is open, liquid is transported through the passageway in the handle assembly and passes through an outlet into the wand assembly. The nozzle 85 is characterized by its low cost construction and by the ability of its atomizing member and spray tip to be easily removed for repair or replacement purposes. Specifically, the nozzle 85 comprises a body or housing 86 preferably injection molded of plastic and having a pressurized air inlet 87 and a pressurized liquid inlet 88. A plastic atomizing member 89 is formed with an upstream end portion 90 which is telescoped in a bore 91 in the housing in communication with the liquid inlet, there being an enlarged seat or collar 92 formed around the atomizing member for seating and sealing against an O-ring 93 in the housing. Liquid from the inlet 88 flows axially through a generally cylindrical passageway 94 in the atomizing member and then is accelerated by a reduced diameter liquid injection port 95 prior to being discharged into a mixing chamber 96. The diameter of the passageway 94 is approximately 2 to 3 times the diameter of the injection port 95. The mixing chamber 96 is defined by a generally cylindrical bore in the downstream end portion of the atomizing member 89, the bore tapering outwardly from the downstream end of the injection port 95. The diameter of the mixing chamber is 3 to 4 times that of the injection port. Pressurized air from the air inlet 87 flows through a circulating chamber 97 and then passes into the mixing chamber 96 through four angularly spaced and radially extending air injection ports 98. The liquid stream is subjected to opposing cross air flows in order to finely atomize the liquid. The atomized liquid is discharged to atmosphere through a spray tip 100 which also is preferably molded of plastic. Herein, the upstream end portion of the spray tip is telescoped into the downstream end portion of the atomizing member 89 and includes a radially outwardly extending flange 101 which seats against the extreme downstream end of the atomizing member. For locking the spray tip 100 to the atomizing member 89 and for preventing relative rotational movement therebetween, the spray tip 100 is formed with an pair of outwardly extending, diametrically opposed keys or lugs 103, which are received in respective keyways in the atomizing member 89. Liquid is sprayed from the tip by way of a discharge orifice 102, which in this case is in the form of an elongated slit for producing a flat spray discharge. In carrying out the invention, the nozzle 85 is provided with a cap 105, preferably molded of plastic, which locks the atomizing member 89 and the spray tip 100 in assembled relation with the housing 86 while allowing quick and easy removal of the atomizing member and the tip for purposes of cleaning, repairing or replacing those components. The cap includes an exposed portion 106 located outside of the housing 86 and formed with a radially inwardly extending flange 107 adapted to abut the downstream face of the flange 101 of the tip. The cap is hollow in order to receive the atomizing member 89 and the tip 100 and co-acts with the flange 101 and the outer periphery of the downstream end portion of the atomizing member to define a groove for receiving an O-ring 108 which establishes an air-tight seal between the atomizing member and the cap. For facilitating predetermined orientation of the spray tip 100 discharge orifice 102 with respect to the cap 105 and for preventing relative rotational movement between the adaptor 89 and spray tip 100 and the cap 102, the spray tip 100 has a hex shaped outer end portion 109 which is received within a central hex shaped aperture of the cap 102. It will be appreciated that such mounting of the spray tip 100 allows the elongated discharge orifice 102 thereof to be indexed at 45 degree intervals with respect to the cap by selective mounting of the spray tip in the hex opening of the cap. The cap 105 further includes a reduced diameter portion 110 disposed in the housing 86 and located in radially outwardly spaced relation with the atomizing member 89 so as to coact with the latter to define the air circulating chamber 97. Pursuant to a further feature of the invention, the housing 86 and the reduced diameter portion 110 of the cap 105 are formed with co-acting means which enable the reduced diameter portion to be inserted linearly into the housing without rotating the cap relative to the housing and, after such insertion, to enable the cap to be locked to the housing by rotating the cap through substantially less than one full turn with respect to the housing. In this instance, these means comprise two diametrically spaced and radially outwardly extending ears 111 formed integrally with the reduced diameter portion 110 of the cap 105. In addition, such means comprise a generally similar pair of diametrically spaced and radially inwardly extending ears 112 molded integrally with the housing 86. The ears 112 are spaced angularly from one another by a sufficient distance to enable the ear 111 to pass between and beyond the ears 112 when the reduced diameter portion 110 of the cap 105 is inserted linearly into the housing 86. With the foregoing arrangement, it will be seen that with the atomizing member 89 and spray tip 100 subassembly locked together they may be assembled in the cap 105 with the discharge orifice 102 of the tip appropriately orientated. For assembling the cap, tip and atomizing member in the housing, the cap is orientated such that the ears, 111 are aligned angularly with the spaces between the ears 112 (see FIGS. 4 and 5). Accordingly, the ears 111 pass between and beyond the ears 112 during insertion of the reduced diameter portion into the housing. As soon as the ears 111 have passed beyond the ears 112, the cap is rotated clockwise (FIG. 2) through approximately one-quarter of a turn by manually gripping and turning the exposed portion 106 of the cap. As a result of such rotation, the ears 111 move into face-to-face relation with the ears 112 (see FIG. 3). Opposing faces of the ears 111 and 112 are formed with appropriately shaped cam surfaces which, during clockwise rotation of the cap, force the cap axially in a direction moving the reduced diameter portion 110 further into the housing 86. As a result, the cap compresses the O-ring 113 and, at the same time, the flange 107 acts against the flange 101 to force the spray tip 100 axially against the atomizing member 89. The axial force is transmitted through the atomizing member to cause the collar 92 thereof to compress the O-ring 93. Accordingly, the atomizing member, the spray tip and the cap are all securely locked to the housing 86 simply by turning the cap through approximately one-quarter of a turn. Lugs 115 on the cap portion 110 in axially spaced relation with the ears 111 engage the ears 112 to limit axial movement of the cap portion into the housing 86. Pursuant to a further feature of the invention, to facilitate orientation of the elongated discharge orifice 102 of the spray tip 100 for the desired direction of the flat spray discharge, the exposed portion 106 of the cap and the housing 86 are formed with respective identifying lugs 114, 118. It will be understood by one skilled in the art that the spray tip 100 may be positioned within the hex opening of the cap 105 during assembly depending upon the desired orientation of the discharging flat spray pattern, such that when the cap 105 is in its fully engaged operative position, the lugs 114, 118 will be alignment. When the cap 105 is removed and replaced, the side-by-side orientation of the identifying lugs 114, 118, provides automatic assurance that the spray tip 100 is properly orientated. The compressed O-rings 93 and 113 urge the cam faces of the ears 111 and 112 into frictional engagement and resist turning of the cap 105 in a counterclockwise direction. By forcibly rotating the cap in that direction, however, the ears 111 may be aligned with the spaces between the ears 112 and the cap then may be pulled away from the housing 86. Thus, the atomizing member 89 and the spray tip 100 may be cleaned or, if desired, replaced with a different type of atomizing member and/or spray tip.

Claims: An air assisted atomizing nozzle assembly (85) comprising a housing (86) having a pressurized liquid inlet (88) and a pressurised air inlet (87), an atomizing member (89) defining (i) a mixing chamber (96) having a longitudinal axis, (ii) a liquid injection port (95) in axial communication with said mixing chamber (96) for injecting a liquid stream axially into said mixing chamber (96), and (iii) a plurality of air injection ports (98) in radial communication with said mixing chamber (96) for injecting a plurality of air streams radially into said mixing chamber (96) thereby to atomize said liquid stream, a spray tip (100) located downstream of said mixing chamber (96) for spraying the atomized liquid into the atmosphere, and means (105) for holding said spray tip (100) and said atomizing member (89) in assembled relation with said housing (86) with said spray tip (100) in communication with said mixing chamber (96) and with said liquid injection port (95) and said air injection ports (96) in communication with said air inlet (87) and said liquid inlet (88), respectively, said means comprising a cap (105) engageable with at least one of said spray tip (100) and said atomizing member (89), characterized by co-acting means (111, 112) on said cap (105) and said housing (86) permitting a portion (110) of said cap (105) to be inserted linearly into said housing (86) without turning said cap (105) relative to said housing (86), and said co-acting means (111, 112) being operable after insertion of said cap portion (110) into said housing (86) and after said cap (105) has been rotated through less than one full turn relative to said housing (86) to lock said cap (105) to said housing (86) and to cause said cap (105) to hold said spray tip (100) and said atomizing member (89) in fixed relation with said housing (86). A nozzle assembly as defined in claim 1 in which said atomizing member (89) includes a seat (92), said co-acting means (111, 112) causing said atomizing member seat (92) to be forced axially into sealed relation with said housing (86) after said cap portion (110) has been inserted linearly into said housing (86) and after said cap (105) has been rotated relative to said housing (86) through less than one full turn to lock said cap (105) to said housing (86). A nozzle assembly as defined in claim 1 or claim 2 in which said spray tip (100) and said atomizing member (89) are separately formed components (103) which are telescoped with one another and have co-acting seats, and means (107) on said cap (105) for forcing said co-acting seats into axial engagement after said cap portion (110) has been inserted linearly into said housing (86) and after said cap (105) has been rotated relative to said housing (86) through less than one full turn to lock said cap (105) to said housing (86). A nozzle assembly as defined in any preceding claim in which said co-acting means (111), (112) comprise a first plurality of angularly spaced ears (111) on said cap portion (110) and further comprise a second plurality of angularly spaced ears (112) in said housing (86), said ears (111) on said cap portion (110) passing between said ears (112) in said housing (86) during linear insertion of said cap portion (110) into said housing (86) and interlocking with the ears (112) in said housing (86) when said cap (105) is rotated relative to said housing (86) in one direction and through less than one full turn. A nozzle assembly as defined in claim 4 in which said co-acting ears (111), (112) are formed with co-acting cam surfaces which draw said cap portion (110) further into said housing (86) when said cap (105) is rotated relative to said housing (86) in said one direction and through less than one full turn. A nozzle assembly as defined in any preceding claim in which said spray tip (100) is formed with an elongated discharge orifice (102) for producing a flat spray discharge, said spray tip (100) having an outer end portion (109) formed with locating plates, and said cap (105) being formed with a central opening with flats for receiving said spray tip (100) in predetermined angular relation and for preventing relative rotation therebetween. A nozzle assembly as defined in claim 6 in which said spray tip (100) has a hex configured outer end portion (109) and said cap opening is hex-shaped. A nozzle assembly as defined in any preceding claim in which said cap (105) and housing (86) each are formed with identifying lugs (114, 118) which are positionable into side-by-side relation when said tip (100) is in a fully and properly mounted position.

Inventors: HARUCH JAMES, OBERG TIM, HARUCH, JAMES, OBERG, TIM
Applicants: SPRAYING SYSTEMS CO, SPRAYING SYSTEMS CO.
Application year: 1995
Main classification: B05B7
IPC codes: B05B1, B05B7, A01M7