Spray nozzle body for use with on / off liquid supply control

Abstract

A spray nozzle assembly having a nozzle body, a spray tip at a downstream end of the nozzle body, and an on / off control for cyclically directing fluid from a fluid supply through an elongated discharge passage of the nozzle body for discharge from the spray tip. The nozzle body discharge passage is sized sufficiently small such that the fluid supply and on / off fluid control are operable for directing fluid through the discharge passage at a rate sufficient that entrained air in the fluid is transmitted with the fluid for discharge through the spray tip. In one embodiment, the nozzle body discharge passage is formed in the nozzle body, in another embodiment the discharge passage is formed in a removable insert of the nozzle body; and in a further embodiment the on / off control discharge passage is operable for supplying fluid to a plurality of turret mounted spray tips.

Description

SPRAY NOZZLE BODY FOR USE WITH ON / OFF LIQUID SUPPLY CONTROLCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 455446, filed March 29, 2023, which is incorporated by reference.BACKGROUND OF THE INVENTION

[0002] Spray nozzle assemblies have long been used in the agricultural industry for spraying various liquids, such as pesticides, herbicides and fungicides, onto agricultural products. These liquids are frequently discharged from moving vehicles such as trucks or tractors. In many locations, there are strict regulations concerning the application of chemicals in agricultural limitations. Moreover, the costs of the chemicals used in such applications are relatively high. Accordingly, targeted application of agricultural chemicals, where only the plant is sprayed and not the surrounding area, is becoming increasingly desirable.

[0003] For maximum flexibility, spray nozzle assemblies used in agricultural applications are often designed to provide maximum flow across a wide range of differently sized spray tips. To this end, these spray nozzle assemblies have nozzle bodies with large internal passages to minimize pressure losses at high flow rates.

[0004] These agricultural application spray nozzle assemblies are typically designed to perform well at all flow rates when spraying continuously. However, problems can arise when using pulse width modulation to control the flow rate of the spray nozzle or when delivering targeted sprays of short duration requiring high precision. Pulse width modulated spray nozzle assemblies use a rapidly cycling solenoid control valve to switch the flow of fluid through the spray nozzle assembly between the on and off states many times per second. The frequency and duty cycle of the valve are electronically controlled to give the required coverage and flow characteristics. The frequency is the number of on-off transitions per second, while duty cycle is the percentage of time the valve remains on over a single on-off period. In such a system the frequency and vehicle speed control the evenness of coverage, liquid supply pressure, and duty cycle to determine the average flow. In targeted spray applications, a metered dose of liquid isdelivered by closely controlling the operation of the nozzle control valve over a single cycle, taking into consideration the valve timing, nozzle capacity, and supply pressure.

[0005] While pulse width modulation can allow for very precise control of the flow rate of a spray nozzle assembly in many situations, as noted, it can lead to significant variability in the flow rate of these spray nozzle assemblies with large internal passages and seals. Targeted spray applications suffer from similar limitations. In particular, operation of the spray nozzle assembly can lead to some air becoming trapped in the nozzle body between the pulse width modulation valve and the spray tip. For example, air can get into the spray system when the nozzles are changed or when liquid otherwise drains out of the system when spraying is stopped. Air can also get into the system when liquid is first directed into the spray nozzle from a boom or the like. This air downstream of the nozzle control valve acts as an accumulator that helps maintain a flow of fluid out of the spray nozzle assembly even after the nozzle control valve is closed. When using pulse width modulation for flow control, this can result in higher than expected flows, and at relatively low duty cycles the flow rate may approach the full rated flow of the nozzle at the supply pressure. This higher than expected flow from the spray nozzle assembly can result in excess chemical being applied to the plants or chemical being applied in areas without plants. In targeted spray applications, the dosage may be different than expected and delayed, due to the continued flow downstream from the nozzle control valve as the trapped air expands after the valve closes.

[0006] In many cases, the air in the spray nozzle body can be purged by the natural vibrations resulting from the vehicle carrying the spray nozzle assembly travelling across a field. Alternatively, the air may be purged by operating the spray nozzle assembly at a 100% duty cycle for a period of time before the start of a spraying operation. Both of these methods are time consuming and potentially wasteful. Moreover, both methods require the trapped air to be broken up by vibration or turbulence, entrained in the fluid stream and carried out of the spray nozzle assembly. In some cases, the nozzle body is configured in a manner that favors air entrapment, such as when the nozzle body has large seals or includes large diameter internal passages, and the air can be difficult to purge. This situation can be exacerbated as the size of the spray tip decreases because the fluid velocity is too low to impart sufficient viscous drag force on the airto overcome its buoyancy. Furthermore, if the air becomes trapped in an eddy or dead area away from the flow path, there is little chance of ever purging it.OBJECTS OF THE INVENTION

[0007] In view of the foregoing, a general object of the present invention is to provide a spray nozzle assembly suitable for pulse width modulated and targeted spray applications that can be controlled to an accurate flow rate even with spray tips designed for low flow rates.

[0008] A further object of the present invention is to provide a pulse width modulated or targeted spray nozzle assembly that avoids air becoming trapped in the nozzle body.

[0009] Another object is to provide a pulse width modulated or targeted spray nozzle assembly that allows faster response to an on / off control while minimizing trapped air that causes inconsistencies in spray pattern and droplet size.

[0010] Still, another object of the present invention is to provide a provide a pulse width modulated or targeted spray nozzle assembly that does not require natural vibration from movement of the spray nozzle assembly or pre-spraying discharge of fluid to eliminate trapped air from the nozzle body.

[0011] A further object of the present invention is to provide a pulse width modulated or targeted spray nozzle assembly of the foregoing type having a nozzle body that is adapted for use with spray tips of different sizes.

[0012] Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0013] FIG. l is a side view of an exemplary pulse width modulated or targeted spray nozzle assembly in accordance with the present invention.

[0014] FIG. 2 is a fragmentary side sectional view of the pulse width modulated or targeted spray nozzle assembly shown in FIG. 1.

[0015] FIG. 3 is a depiction of a prior art fluid flow path that includes multiple dead spaces that can cause air to become trapped in the fluid resulting in inconsistencies in the spray pattern and droplet size.

[0016] FIG. 4 is a side elevational view of an alternative embodiment of pulse width modulated or targeted spray nozzle assembly according to the invention.

[0017] FIG. 5 is a fragmentary side sectional view of the pulse width modulated or targeted spray nozzle assembly shown in FIG. 4.

[0018] FIG. 6 is a side view of still another alternative embodiment of a pulse width modulated or targeted spray nozzle assembly incorporating the present invention that includes a rotating spray turret.

[0019] FIG. 7 is a side sectional view of the pulse width modulated or targeted spray nozzle assembly shown in FIG. 6.

[0020] 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.DETAILED DESCRIPTION OF THE INVENTION

[0021] Referring now more particularly to FIGS. 1-2 of the drawings, there is shown an illustrative pulse width modulated or targeted spray nozzle assembly 10 in accordance with the present invention. One example of an application in which the illustrated spray nozzle assembly 10 has particular utility is agricultural applications in which chemicals are being applied in a controlled or targeted manner to plants or other agricultural products without excess spray in surrounding areas. However, it should be understood that the present invention is not limited to any particular application and instead could be used in any spraying application in which pulse width modulated or other on / off control of the spray discharge rate is desired. Relatedly, it should be understood that the spray nozzle assembly 10 of the present invention is not limited to any particular spray fluid or spray target and instead may be used to discharge any suitable fluid onto any suitable target.

[0022] For producing a controlled on / off flow condition, a liquid controller is provided that is operable for producing a pulse width modulated flow or an on / off flow suitable for spotspraying. The illustrated spray nozzle assembly 10 is equipped with a pulse width modulation (PWM) valve assembly 12. The PWM valve assembly 12 is configured to allow the spray nozzle assembly 10 to achieve a pulsing flow that rapidly alternates between on and off flow conditions. To this end, the PWM valve assembly 12 may include an electrically actuated on / off solenoid that can oscillate rapidly between an open position in which fluid is allowed to pass into the spray nozzle assembly 10 and a closed position in which the flow of fluid into the spray nozzle assembly 10 is blocked. The use of the PWM valve assembly 12 can allow the flow rate produced by the spray nozzle assembly 10 to be adjusted in a very precise manner without changing the pressure of the fluid supply simply by adjusting the on / off duty cycle of the spray nozzle assembly 10 via the PWM valve assembly 12. The PWM valve assembly may be of a commercially known type such as offered by Spraying Systems Co., assignee of the present application, under the trademark DynaJet. Various components and their mode of operation of the illustrated spray nozzle assembly 10 and PWM valve assembly 12 may be similar to those described in U.S Patent No. 7,086,613, the disclosure of which is incorporated herein by reference.

[0023] While the present invention is particularly applicable to spray nozzle assemblies utilizing PWM flow control, it should be understood that the nozzle body configurations of the present invention are not limited to use with a PWM valve. For example, the teachings of the present invention could be utilized in any application requiring quick response from a low flow nozzle and nozzle body, such as targeted spraying.

[0024] In the illustrated embodiment, the spray nozzle assembly 10 further includes a nozzle body 16 with an attached spray tip 18 through which fluid is discharged. In the illustrated embodiment, the PWM valve assembly 12 is attached to an upstream end 20 of the nozzle body 16 with a portion of the PWM valve assembly 12 being received in a recess in the nozzle body 16. The PWM valve assembly 12 is secured to the nozzle body 16, in this case, by a valve lock ring 22. As shown in FIG. 2, the illustrated lock ring 22 is internally threaded and engages with external threads on the upstream end 20 of the nozzle body 16 while capturing an annular shoulder on the PWM valve assembly 12. Similarly, the spray tip 18 is attached to the downstream end of the nozzle body 16 by a retaining cap 24 that, in this case, engages with a rib 26 on the exterior of the nozzle body 16 and an exterior shoulder 28 on the spray tip 18. It shouldbe understood that the present invention is not limited to any particular method for connecting the spray tip 18 or the PWM valve assembly 12 to the nozzle body 16.

[0025] For connection to a supply of fluid, the nozzle body 16 includes a fluid inlet 30 in this case on a side of the nozzle body 16 as shown in FIG. 2. The fluid inlet 30 communicates with a nozzle fluid inlet passage 32 in the nozzle body 16 that carries fluid into the PWM valve assembly 12. To this end, the nozzle fluid inlet passage 32 communicates with a valve fluid inlet passage 34. The valve fluid inlet passage 34, in turn, carries fluid to a valve element 36 and associated valve seat 38. As discussed above, the valve element 36 oscillates rapidly between open and closed positions relative to the valve seat 38 so that when in the open position the valve element 36 permits fluid to flow in the downstream direction past the valve seat 38. Fluid that passes the valve seat 38 in the downstream direction when the valve element 36 is in the open position exits the PWM valve assembly 12 via a valve outlet passage 40 that extends in the downstream direction from the valve seat 38.

[0026] To achieve accurate and repeatable fluid delivery in PWM applications, it has been found that air trapped in the fluid path downstream from the PWM valve must be eliminated as much as possible. To that end, the nozzle body 16 has an internal geometry that facilitates removal of entrained air and minimizes dead spaces between the PWM valve and the nozzle. Dead space is any area outside the main fluid path between the PWM valve and the nozzle, For purposes herein, dead space, as depicted in FIG. 3, means gaps in joints between mating parts, areas of relatively large diameter resulting in reduced fluid velocity and / or eddies, and intersecting passages where one branch runs past another forming a blind end. The latter regions are not uncommon at the intersection of drilled holes or cores in injection molded parts where the fluid path changes direction.

[0027] Nozzle bodies are typically designed with intentionally large passages to minimize pressure losses and accommodate a wide range of fluid flows, with little regard to purging trapped air. When nozzle bodies of such type are used with small capacity spray nozzles (lower flow rates), the downward fluid velocity may not be enough to overcome the upward velocity of entrained air bubbles, preventing their escape.

[0028] For enabling the spray nozzle assembly 10 to be controlled to a precise flow rate even with spray tips designed for low flow rates, the nozzle body 16 has a discharge passage 42configured to minimize areas where air can be become trapped while helping to ensure that a sufficient fluid velocity is maintained to carry out any air that is introduced by operation of the PWM valve assembly 12. To this end, the downstream end of the valve assembly outlet passage 40 in this case transitions into an inlet section 44 at the upstream end of the nozzle body discharge passage 42. In the illustrated embodiment, the valve outlet passage 40 is substantially straight and would be arranged vertically if the spray nozzle assembly 10 is arranged to spray downward such as in an agricultural spraying operation. The inlet section 44 is tapered such that its diameter gradually reduces as the inlet section 44 extends in the downstream direction. More specifically, the upstream end of the inlet section 44 has a diameter that substantially matches the diameter of the valve outlet passage 40. Throughout this inlet section 44, the fluid passage tapers consistently inward such that the diameter is gradually decreased down to a reduced diameter of the nozzle body discharge passage 42 that then remains fixed throughout the remainder of the discharge passage 42.

[0029] In sharp contrast to a typical transition region between the PWM valve assembly and a nozzle body that has an increasing diameter, a continuous reduction in diameter through the inlet section 44 helps ensure that a sufficient fluid velocity is produced in the nozzle body discharge passage 42 to carry any trapped air out of the spray nozzle assembly 10. Moreover, the reduced and consistent diameter of the nozzle body discharge passage 42 downstream of the inlet section 44 is selected so as to maintain a fluid velocity high enough to overcome buoyancy of any trapped air. This is in contrast to typical nozzle bodies that generally have relatively larger diameter discharge passages in order to minimize fluid pressure loss. Suitable discharge passage diameters based upon fluid flow rates that ensure sufficient velocity to purge entrained air and negligible frictional pressure loss has been found to be:Flow - Liters Per Minute (LPM) Maximum discharge passage diameter (mm) .1 - .2 1.6.3 - .4 3.8 - 1 4

[0030] The illustrated nozzle body 16 further has a relatively short discharge passage 42. Similarly, the illustrated PWM valve assembly 12 also has a relatively short outlet passage 40,such that the length of the flow path downstream of the valve seat 38 is minimized. In some embodiments, it may be advantageous to further minimize the length of the nozzle body discharge passage 42 in order to minimize pressure losses as the fluid travels through the nozzle body 16 while also minimizing areas where air can become trapped.

[0031] In the illustrated embodiment, the nozzle body discharge passage 42 is substantially straight and in alignment with the valve outlet passage 40 such that fluid is able to travel a substantially straight path from the valve seat 38 to the spray tip 18. This substantially straight, unobstructed flow path again helps eliminate areas in which air can become trapped. To the extent some air becomes trapped, a configuration of the foregoing type helps minimize the volume of trapped air in the fluid flow stream. Additionally, the interface 46 between the PWM valve assembly 12 and the nozzle body 16 is configured so that no internal seals (i.e., seals within the fluid flow path) are necessary at the interface 46 therebetween. In the illustrated embodiment, the only seal between the portion of the PWM valve assembly 12 that includes the valve outlet passage 40 and the nozzle body 16 is an O-ring 48 that is arranged external to the valve outlet passage 40. To the extent a seal is provided in the fluid flow path in some embodiments, the size of the seal should be minimized and the seal should be located, when possible, where the fluid is travelling vertically. Such an arrangement will help reduce the possibility of air becoming trapped in the vicinity of the seal and minimize the volume of any air that does become trapped. The illustrated configuration of the valve outlet passage 40 and nozzle body discharge passage 60 helps eliminate or minimize areas of low fluid velocity outside of the main fluid flow / stream. If in some embodiments such areas are difficult to avoid, the fluid passages should be configured so that such areas are not located at a high point of the fluid stream.

[0032] Referring now to Figs. 4 and 5, there shown an alternative embodiment of a pulse width modulated or target spray nozzle assembly 70 according to the invention wherein items similar to those described above have been given similar reference numerals. The spray nozzle assembly 70 comprises a nozzle body 71, an on / off controller such as a pulse width modulation (PWM) valve assembly 12 secured to an upstream end of the nozzle body 71 by a lock ring 22 for controlling the supply of liquid from a liquid supply, and a spray tip 18 at a downstream end of said nozzle body.

[0033] For connection to a supply of fluid, the nozzle body 71 in this case includes a quick disconnect receptacle 72 that receives a strainer body 74. The strainer body 74 has a fluid inlet 75 that communicates with a strainer 76 housed within the strainer body 74 and in turn with a fluid inlet passage 32 in the nozzle body 71 that directs fluid to the PWM valve assembly 12. The fluid inlet passage 32 again communicates with a valve inlet passage 34 which, as described above, directs fluid to a PWM valve assembly 12 and associated valve seat 38. As discussed above, the PWM valve assembly 12 is operated to oscillate between open and closed positions relative to the valve seat 38 so that when in the open position the valve element 36 permits fluid to flow in the downstream direction from the valve seat 38 to a central valve outlet passage 40.

[0034] For controlling a precise fluid flow to a spray tip 18 at low flow rates, the nozzle body 71 in this case is fitted with an elongated nozzle insert 78 formed with a discharge passage 80 that again is configured to minimize areas where air can become trapped and for carrying out any air that may be introduced in operation of the PWM valve assembly 12. To that end, the downstream end of the PWM valve assembly 12 outlet passage 40 again communicates with an inlet section 81 of the nozzle body insert discharge passage 80. The inlet section 81 again tapers gradually to a reduced diameter of the discharge passage 80 which remains fixed throughout the length of the removable nozzle insert 78 so as to overcome the buoyance of any trapped air. The removable nozzle insert discharge passage 80 again is substantially straight and in alignment with the valve outlet passage 40 such that fluid is able to travel in a substantially straight path to the spray tip 18 for eliminating areas in which air can become trapped.

[0035] To allow the nozzle body 71 to be readily adapted for use with spray tips 18 of different sizes, the removable nozzle insert 78 is configured to mate with the internal geometry of differently sized spray tips 18. The removable insert discharge passage 80 extends to a downstream end of the removable nozzle insert 78 and communicates directly between the control valve outlet passage 40 and the spray tip 18. In particular, the removable nozzle insert 78 includes an upstream inlet section 81 and a downstream head portion 84 received in an internal recess 85 in the spray tip 18. The downstream head portion 84 of the removable nozzle insert 78 has an external geometry configured to mate with the internal geometry of the internal recess 85 in the spray tip 18. Thus, the same nozzle body 71 can be used with different types of spray tips 18 simply by changing the removable nozzle insert 78 to a nozzle insert having a downstreamhead portion 84 with a geometry that is complementary to the internal geometry of the spray tip 18 to be used. The internal geometry of spray tips 18 can vary in a variety of ways and thus the downstream head portion 84 of the insert 78 can have a variety of different configurations, for example the shape or size may vary in order to mate with the spray tip 18. The only seals associated with the removable insert 78 in this case is an upstream seal 64 between an upstream end of the removable insert 78 and the nozzle body 71 and a downstream seal between a downstream end of the removable insert and the inner surface of the spray tip 18. Again, there are no dead spaces in the fluid flow path. Hence, it can be seen that the removable nozzle insert 78 again can have a relatively small diameter discharge passage 80 size proportional to the particular spray tip 18 used such that the fluid velocity is high enough to overcome the buoyance of any entering air.

[0036] Still a further embodiment of a spray nozzle assembly 110 according to the present invention in which the internal fluid flow path has been configured to minimize trapped air is shown in FIGS. 6 and 7. The embodiment of FIGS. 6 and 7 includes a nozzle body 112 with a base member 114 that supports a rotating turret-type nozzle head 116 with, in this case, three spray positions (two of which can be seen in FIGS. 6 and 7) for easy change between different spray tips. In this case, the base member 114 of the nozzle body 112 includes a fluid inlet 118 that communicates with an inlet passage 120 that carries fluid to a PWM valve assembly 122. An outlet passage 126 is provided in the base memberl 14 downstream of the PWM valve assembly 122 or other on / off fluid supply control that carries the fluid to the rotating nozzle head 116. As noted above, the nozzle head 116 is rotatably supported in a downstream end portion of the nozzle base member 114.

[0037] The nozzle head 116, in this case, includes three legs 128 (two of which are visible in FIGS. 6 and 7) each of which is configured for connection to a spray tip at the respective leg’s downstream end. In the illustrated embodiment, the spray nozzle assembly 110 is configured to discharge out of one leg 128 at a time. It should be appreciated any suitable spray tip may be used on each of the legs, including, for example, the spray tip illustrated in the embodiment of FIGS. 1 and 2. However, using a different spray tip on each leg 128 is advantageous in that allows a user to quickly change between different spray characteristics. As shown in FIG. 6, each leg 128 of the rotating nozzle head 116 includes a discharge passage 130 that may be selectivelyplaced into communication with the outlet passage 126 of the base member 114 by rotating the nozzle head 116. To facilitate this connection, the upstream end of the discharge passage 130 has a relatively larger diameter inlet section 132 that can be brought into alignment with an exit interface portion 134 of the outlet passage 126 in the base member 114 of the nozzle body 112. In this case, the inlet section 132 of the discharge passage 130 has a significantly smaller diameter than the exit interface portion 134 of the outlet passage 126. Additionally, the remaining portion 135 of the discharge passage 130 downstream of the inlet section 132, in turn, has a relatively smaller diameter than the inlet section 132. Again, this reduction in diameter of the downstream section of the discharge passage 130 in relation to the fluid velocity produced in the discharge passage 130 carries any trapped air out of the spray nozzle assembly 110. As opposed to having a step down in the diameter of the passage at the upstream end of the discharge passage 130, a gradually tapered decrease in the diameter could be provided similar to the inlet section of the discharge passage in the embodiment of FIGS. 1 and 2. As noted above, typical spray nozzles have discharge passages with diameters that increase after the inlet section as opposed to decrease such as shown in FIG. 4. In the illustrated embodiment, the relatively smaller discharge passages in the legs 128 of the rotating head 116 allow for core outs 136 to be formed in the outer surfaces of the legs 128 such as shown in FIG. 6. In some embodiments, these core outs 128 can help with molding of the rotating head 116 of the nozzle body 112.

[0038] The embodiment illustrated in FIGS. 6 and 7 does not include a removable insert for facilitating attachment of the spray tips. Instead, the downstream ends of each of the legs 128 includes a respective recess for receiving a gasket that can be used to help seal the connection between the spray tips and the rotating head 116 when the spray tips are secured in place on the legs 128 using, for example, a nozzle retaining cap like that of the embodiment of FIGS. 1 and 2. However, a removable insert like that shown in FIG. 2 could also be used with the embodiment of FIGS. 6 and 7 instead of a gasket.

[0039] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0040] The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are tobe construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0041] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

What is claimed:

1. A spray nozzle assembly comprising; a nozzle body having a fluid inlet; an on / off fluid control for cyclically directing fluid from a fluid supply to an outlet passage of said on / off fluid control; said nozzle body having an elongated discharge passage smaller in diameter than said on / off fluid control outlet passage for receiving fluid from said on / off fluid control passage for direction through said nozzle body; a spray tip at a downstream end of said nozzle body for receiving and spraying fluid from said elongated discharge passage; and said nozzle body discharge passage being sized sufficiently small in relation to said on / off control fluid outlet passage such that the velocity of fluid directed through said nozzle body discharge passage overcomes the buoyance force of any air entrained in the fluid and carries the entrained air for discharge with sprayed fluid.

2. The spray nozzle assembly of claim 1 in which an upstream end of said removable body elongated discharge passage is formed with an inwardly converging entry passage section for directing fluid from said on / off control outlet passage into and through said nozzle body elongated discharge passage.

3. The spray nozzle assembly of claim 1 in which said flow of fluid through said on / off control outlet passage, said nozzle body discharge passage, and spray tip is free of contact with sealing elements.

4. The spray nozzle assembly of claim 1 in which said on / off fluid control is a pulse width modulating valve assembly.

5. The spray nozzle assembly of claim 1 in which said on / off fluid control is operative for directing fluid through said nozzle body discharge passage and said spray tip for spot spraying.

6. The spray nozzle assembly of claim 1 in which said on / off fluid control outlet passage is substantially straight and aligned with said removable insert discharge passage such that fluid travel is in a substantially straight path from said on / off control valve outlet passage to said spray tip.

7. The spray nozzle assembly of claim 6 in which the on / off control valve discharge passage and said nozzle body inlet passage meet with no seals at the interface there between the fluid flow path.

8. The spray nozzle assembly of claim 1 in which said nozzle body discharge passage is formed in a removable insert mounted in said nozzle body.

9. The spray nozzle assembly of claim 8 in which said removable insert includes a head portion sized for receiving said spray tip.

10. A spray nozzle assembly comprising; a nozzle body having a fluid inlet; an on / off fluid control for cyclically directing fluid from a fluid supply to an outlet passage of said on / off fluid control; said nozzle body having an elongated discharge passage for receiving fluid from said on / off fluid control passage for direction through said nozzle body; a spray tip at a downstream end of said nozzle body for receiving and spraying fluid from said nozzle body elongated discharge passage; said on / off fluid control outlet passage and said nozzle body discharge passage defining an internal geometry free of dead spaces; and(a) said nozzle body discharge passage being sufficiently small and (b) said fluid supply and on / off fluid control being operable for directing fluid through said discharge passage at a rate sufficient that entrained air in the fluid is transmitted with the fluid for discharge through the spray tip.

11. The spray nozzle assembly of claim 10 in which said fluid supply and said on / off fluid control are operable for directing fluid through said nozzle body discharge passage at a flow rate of 0.1-0.2 LPM, and said nozzle body discharge passage has a diameter no greater than 1.6 millimeter.

12. The spray nozzle assembly of claim 10 in which said fluid supply and said on / off fluid control are operable for directing fluid through said nozzle body discharge passage at a flow rate of 0.3-0.4 LPM, and said nozzle body discharge passage has a diameter no greater than3 millimeter.

13. The spray nozzle assembly of claim 10 in which said fluid supply and said on / off fluid control are operable for directing fluid through said nozzle body discharge passage at a flow rate of 0.8-1.0 LPM, and said nozzle body discharge passage has a diameter no greater than4 millimeter.

14. The spray nozzle assembly of claim 10 in which said on / off fluid control is a pulse width modulating valve assembly.

15. The spray nozzle assembly of claim 10 in which said on / off fluid control is operative for directing fluid through said nozzle body discharge passage and said spray tip for spot spraying.

16. The spray nozzle assembly of claim 10 in which said nozzle body discharge passage is formed in a removable insert mounted in said nozzle body.

17. The spray nozzle assembly of claim 16 in which said removable insert includes a head portion sized for receiving said spray tip.

18. A liquid spraying system comprising:a base member having a fluid passage for connection to a fluid supply; a turret head rotatable supported by said base member; an on / off fluid control for cyclically directing fluid from said fluid supply and base member fluid passage to an outlet passage of said on / off fluid control; said turret head having a plurality of legs each carrying a respective spray tip; said turret head legs each having a discharge passage communicating with the spray tip carried by the respective turret leg; said turret head being rotatable relative to the base member for selectively positioning the discharge passage of a respective turret leg in communication with the outlet passage of the on / off fluid control; and(a) said discharge passage of each turret leg being sized sufficiently small and (b) said fluid supply and on / off fluid control being operable for directing fluid through said discharge passage of each turret leg at a rate sufficient that entrained air in the fluid is transmitted with the fluid for discharge through the spray tip.

19. The spray nozzle assembly of claim 18 in which said flow rate of fluid through said on / off fluid control outlet passage, said turret leg discharge passage, and the spray tip supported thereon is free of contact with sealing elements.

20. The spray nozzle assembly of claim 18 in which said on / off fluid control is a pulse width modulating valve assembly.

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