Liquid distribution system with pressurized air-operated liquid control piston

Abstract

A modular liquid dispensing system, wherein each module has a module body, a spray nozzle, and a piston for controlling the dispensing of liquid from the nozzle. Each module has a pneumatic actuation system that moves the piston to the open position and facilitates quicker return movement to the closed position, allowing for the dispensing of precisely controlled droplet-sized amounts of highly viscous liquids.

Description

[Background Art]

[0001] [Cross-Reference to Related Applications]

[0002]

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 076,001 filed on September 9, 2020, which is incorporated herein by reference.

[0003] [Field of the Invention]

[0004]

[0002] The present invention relates to a liquid dispensing system, and more particularly, to a liquid dispensing system having a nozzle for dispensing controlled small amounts of high-viscosity liquid.

[0005] [Background of the Invention]

[0006]

[0003] Many industries require the dispensing of small, controlled amounts of high-viscosity liquid. For example, in the food industry, in the commercial production of pizza, it is necessary to dispense droplet-sized amounts of sauce onto pizza dough. Due to the thick nature of the sauce, it is difficult to rapidly dispense tightly controlled small droplets as desired. Moreover, when the sauce contains solids that may clog the nozzle passage, the size of the fluid path must be increased, which makes it more difficult to control droplet dispensing, often resulting in undesirable splattering of the discharged sauce. Furthermore, when the dispensing device uses an air-operated liquid control piston, rapid actuation of the piston is limited by the compressibility of the control air. In addition, when an air-operated device is spring-returned, the spring return force can be limited to about half of the air pressure used to open the device, which resists rapid piston closure.

[0007] Object and Summary of the Invention

[0008]

[0004] An object of the present invention is to provide a liquid dispensing system having a spray nozzle effective for accurately controlling and dispensing droplet-sized amounts of high-viscosity liquid.

[0009]

[0005] Another objective is to provide a liquid distribution system characterized as described above that is effective in rapidly depositing precisely controlled, pixel-sized droplets without causing undesirable splashing of the liquid.

[0010]

[0006] A further objective is to provide the above-described liquid distribution system in which the spray nozzle can operate in a larger inlet passage that is less susceptible to clogging due to the solid content in the liquid.

[0011]

[0007] Another objective is to provide such a liquid distribution system that can operate selectively to distribute precisely controlled droplets of different sizes.

[0012]

[0008] Another objective is to provide such a liquid distribution system that can operate more quickly.

[0013]

[0009] Another objective is to provide such a liquid distribution system having an air-operated piston with a return spring whose function is not very resistant to the air pressure used to operate the system.

[0014]

[0010] Another objective is to provide the aforementioned type of liquid distribution system that is relatively simple in design and suitable for economical manufacturing and efficient use.

[0015]

[0011] Other objects and advantages of the present invention will become apparent by reading the following detailed description and referring to the drawings. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a fragmentary perspective view of an exemplary modular liquid distribution system according to the present invention. [Figure 2] Figure 2 is a perspective view of a fully assembled liquid distribution system. [Figure 3] Figure 3 shows a vertical cross-section of one of the liquid distribution modules of the illustrated liquid distribution system. [Figure 4] Figure 4 is an enlarged vertical cross-section of the central liquid control piston assembly of the liquid distribution module shown in Figure 3. [Figure 5] Figure 5 is an enlarged perspective view in vertical cross-section of one of the spray nozzle assemblies in the liquid distribution module of the illustrated system. [Figure 6] Figure 6 is a vertical cross-section of the spray nozzle assembly shown in Figure 5. [Figure 7] Figure 7 is an exploded perspective view of the spray nozzle assembly shown in Figures 5 and 6. [Figure 8] Figure 8 is a schematic diagram of the solenoid control valve associated with each liquid distribution module.

[0020] The present invention is susceptible to various modifications and alternative configurations, but certain exemplary embodiments thereof are shown in the drawings and described in detail below. However, it should be understood that the present invention is not intended to be limited to the specific forms disclosed, but rather intended to cover all modifications, alternative configurations, and equivalents that fall within the spirit and scope of the invention. Detailed description of preferred embodiments

[0017]

[0021] Next, referring more specifically to Figures 1-3 of the drawings, an exemplary liquid distribution system 10 according to the present invention is shown. The exemplary liquid distribution system 10 is in the form of a modular valve manifold 11 including a plurality of individual liquid distribution modules 12, which are supported and held in a sealed, side-by-side stacked relationship between end blocks 13 and 14 at both ends, which are fixed to each other by tie rods 15 and nuts 16. Each module 12 includes a module nozzle support body 20, which is formed by a liquid supply port 21 provided in a relationship aligned with the liquid supply port 21 of an adjacent module 12 in order to define a common liquid supply passage 22 communicating between a liquid inlet port 23 at the upstream end block 13 and a liquid outlet port 24 at the downstream end block 14. Thus, liquid directed to the inlet 23 communicates through each of the stacked modules 12.

[0018]

[0022] Each illustrated module 12 has its own spray nozzle 30, which is mounted on the underside of a module nozzle support body 20 having an upstream liquid inlet 31 on its upper side that communicates with a liquid supply passage 22. To control the liquid from the common liquid supply passage 22 to the spray nozzle inlet 31 of each module 12, a piston 32 is supported within each module body 20 above the spray nozzle inlet 31 and reciprocates between a raised inlet open position and a lowered inlet closed position.

[0019]

[0023] In this case, each piston 32 is supported to move selectively relative to another within a carrier 33 fitted in a sealed relationship within a vertical opening 34 of the respective module body 20, and the downstream end of the piston 32 extends through a liquid supply passage 22 to engage with a spray nozzle inlet 31. A return spring 35 is provided inside a spring chamber 36 of the module body 20 in an insertion relationship between the head 32a of the piston 32 and a retaining sleeve 37 fixed inside the upper end of the body opening 34 and held by a retaining cap 38 screwed inside the upper end of the body opening 34. In this case, the retaining sleeve 37 extends downward around the return spring 35 and the piston head 32a, as best shown in Figures 3 and 4. In this case, the spring retaining sleeve 37 and the opening 34 of the module body 20 define an annular air passage 40 (Figure 3) around the retaining sleeve 37, which communicates with and penetrates the spring chamber 36 through a circumferentially offset hole 41 within the spring retaining sleeve 37. A sealed piston chamber 42 is formed between the opposing axial ends of the piston head 32a and the carrier 42 (Figure 4).

[0020]

[0024] In accordance with a key feature of this embodiment, each module body has a pressurized air passage system controlled by its respective valve, such that the pressurized air that moves the piston to the open position also increases the rapid movement of the piston to the closed position. In the illustrated embodiment, the movement of the piston 32 of each module 12 between the open and closed positions is controlled by its respective solenoid valve 43, as best shown in Figures 3 and 8. The solenoid valve 43 of each module is mounted to the respective module body 20 in such a manner that the solenoid mounting block 44 is sealed to the respective module body 20 by screws 45. Each module body 20 has an air supply port 50 aligned with the air supply port 50 of each adjacent module body and defines a common air inlet passage that communicates with a system air inlet port 51 in the end block 14. Furthermore, each module body 20 has an air outlet port 52 aligned to define a common outlet air passage that communicates with a system exhaust outlet port 53 in the end block 14. The air supply port 50 of the module body 20 communicates with the air inlet port 55a of the solenoid valve 43 via the inlet air passages 63, 63a and the solenoid mounting block 44 within the module body 20. The air outlet port 52 of the module body 20 communicates with the return spring chamber 36 via the outlet passage 60, through the hole 41 of the retaining sleeve 37 and the annular passage 40 around the sleeve 37, and the outlet passages 61, 61a and the solenoid mounting block 44 of the module body 20 communicate with the exhaust port 55b of the solenoid valve 43. The piston chamber 42 communicates with the work port 55c of the solenoid control valve 43 via the work passages 62, 62a and the solenoid mounting block 44 within the module body 20.

[0021]

[0025] In this case, when the solenoid valve 43 is in its natural state or de-energized state, the inlet pressure at the solenoid valve port air inlet 55a is blocked by the mechanism 43a (in the form of a stem in this case) of the solenoid valve 43 (Fig. 8), preventing the pressurized air at the air supply port 50 of the module body 20 from communicating with the piston chamber 42 via the solenoid mounting block 44 and the passages 62a, 62 in the module body 20. When the solenoid valve 43 is in its natural state or de-energized state, an additional passage connects the ports 55c and 55b of the solenoid valve 43, enabling air communication between the piston chamber 42 and the outlet port 52 in the module body 20 via the passages 62, 62a in the module body 20 and the solenoid mounting block 44, the outlet passages 61a, 61 in the solenoid mounting block 44 and the module body 20, the annular passage 40 passing through the spring 35 via the hole 41, and the outlet passage 60.

[0022]

[0026] When the solenoid valve 43 is energized, the solenoid shifts the actuating mechanism 43a to close the exhaust port 55b, disconnect the connection of the port 55c to the atmosphere, and connect the solenoid valve ports 55a and 55c. Next, the air pressurized at the air supply port 50 of the module body 20 communicates with the pressure chamber 42 via the passages 63, 63a in the module body 20 and the solenoid mounting block 44, the solenoid valve ports 55a, 55c and the passages 62a, 62, causing the piston 32 to stroke upward, open the nozzle inlet 31, and compress the return spring 35. The upward stroke of the piston head 32a provides a positive air displacement inside the spring chamber 36, resulting in a slight pressure increase. The pressure increase in the spring cavity 36 is discharged to atmospheric pressure through the hole 41 in the spring holding sleeve 37, the annular passage 40, the outlet passage 60, and the air outlet port 52 (Figs. 3 and 4). The nozzle inlet 31 remains open, allowing liquid to flow from the common liquid supply passage 22 through the spray nozzle 30 to the atmosphere while the solenoid is energized.

[0023]

[0027] When not energized, the solenoid valve 43 returns to its natural state. Inlet air pressure at the solenoid port 55a is cut off again, preventing pressurized air from entering the device. The rapid depressurization of the pressurized air in the piston chamber 42 causes migration of increased pressure into passages 62, 62a in the module body 20 and the solenoid mounting block 44, ports 55c and 55b of the solenoid valve 43, outlet passages 61a and 61 in the solenoid mounting block 44 and the module body 20, the spring chamber 36, an outlet passage 60, and an outlet port 52 as the system pressure in the piston chamber 42 is released and equalizes with atmospheric pressure. The migrating pressure in the annular passage 40 communicates through a hole 41 in the spring retaining sleeve 37, generating increased pressure in the spring chamber 36 and acting on the surface area of the piston head 32a in the spring chamber 36. As a result, an instantaneous downward force is generated to supplement the constant downward force from the return spring 35 opposing the reduced pressure in the piston chamber 42, returning the piston 32 to its natural state, closing the passage 31, and stopping the inflow of liquid from the common liquid supply passage 22 through the spray nozzle 30. The significant reduction in the time required to return the piston 32 to its natural state is attributed to the instantaneous increase in pressure inside the spring chamber 36. All passages and cavities downstream of the solenoid valve 43, including the spring chamber 36, essentially return to atmospheric pressure via the outlet port 52, effectively removing the transient pressure applied to the piston head 32a.

[0024]

[0028] Further operation of the liquid distribution module 12 by re-energizing the solenoid 43 is unaffected by the previous cycle of increased pressure in the spring chamber 36, since the increased pressure is temporary and quickly returns to atmospheric pressure, which allows the desired effect to be imparted to the opening stroke of the piston 32 without affecting the closing stroke of the piston 32. As will be apparent, the solenoid valve 43 can be cycled at a predetermined rate for specific dispensing operations with variable opening times of the piston 32 to provide variable pixel volumes.

[0025]

[0029] In a further aspect of this embodiment, each spray nozzle module 12 is operable to distribute controlled, small, circular, pixel-sized droplets of a highly viscous liquid in conjunction with the circulation of the piston 32, even when the liquid has a considerable solid content. Referring particularly to Figures 5, 6, and 7, each spray nozzle 30 in this case comprises a nozzle body 70, a nozzle seat 71, and an internal nozzle core 72. In this case, the nozzle seat 71 has an externally threaded cylindrical downstream end 73 that screws into an upstream cylindrical end 74 of the nozzle body 70 to secure the nozzle core 92 inside the nozzle body 70. The upstream end 75 of the nozzle seat 71 defines a liquid inlet 31 of a predetermined size located at the upstream end of the assembly. In this case, the nozzle core 72 has an upstream cylindrical mounting flange 78, which is located on an annular ledge 79 inside the nozzle body 70 and held in place by the nozzle seat 71, although it will be understood that other methods may be used to secure the nozzle core 72 inside the nozzle body 70.

[0026]

[0030] The cylindrical mounting flange 78 of the core 72 has a downstream end wall 80 that is concave (with respect to the direction of fluid inflow) and is formed of a plurality of liquid orifices 81 that are spaced circumferentially and axially oriented. These liquid orifices communicate with the expansion cavity 82 of the nozzle seat 71 and the annularly configured liquid discharge passage defined between the nozzle core 72 and the nozzle body 70, guiding the liquid in a controlled manner to be optimally distributed in the form of small droplets, as will be revealed later. The illustrated nozzle 30 comprises a multi-part assembly, but it will be understood that, alternatively, it may have a one-part structure or fewer or more assembly parts.

[0027]

[0031] In carrying out this aspect of this embodiment, the nozzle core 72 has a teardrop-shaped pintle 83, which, together with the inner surface of the surrounding nozzle body 70, defines an expanding discharge passage 85 that reduces the outlet velocity of the distributed liquid, thereby maintaining a desired flow rate and a constant droplet size of the high-viscosity discharge liquid. For this purpose, the illustrated pintle 83 (see Figures 5, 6, and 7) has a relatively small-diameter upstream end section 86 extending centrally from the mounting flange 78, a curved section 87 extending radially outward adjacent to the upstream end, and a relatively long, tapered conical end section 90. As described above, the nozzle body 70 has a substantially hollow cylindrical configuration, and the inner surface of the nozzle body 70 defines the outer wall of the annular discharge passage 85 around the core section 72. The inner wall of the discharge passage 85 is defined by the outer surface of the pintle 83. In this case, the inner surface of the nozzle body 70 includes a section 91 that extends radially outward, surrounding the outwardly curved section 87 of the nozzle core 72, and a uniform diameter section 84 that extends downstream for approximately the remaining length of the pintle 83. This design is unique in that the inflow through the annular discharge passage causes the viscous liquid to expand inward as it moves through the nozzle body. The geometric shape of the pintle defines the inner diameter wall of the annular flow path and provides a structure that can form a vacuum due to the inflow expansion. The deceleration of the liquid in the expanding annular discharge path is a function of capillary forces and surface tension that pull the vacuum and resist the inflow.

[0028]

[0032] During operation, continuing to refer to Figure 3, when the piston 32 is in the raised inlet-open position, the liquid is allowed to pass through the nozzle inlet 31 in a controlled manner and enter the expansion cavity 82 defined inside the cylindrical downstream end of the nozzle seat 71. The liquid passing through the nozzle inlet 31 is directed towards the impact surface defined by the concave downstream end wall 80 of the expansion cavity 82. This fills the expansion cavity 82, and the liquid is then pushed out of the expansion cavity into the discharge passage 85 through a series of circumferentially spaced orifices 81. Furthermore, the size of the orifices 81 is at least the same as the size of the nozzle inlet 31, allowing solid particles in the liquid to flow from the expansion cavity 82 into the fluid discharge passage 85 without clogging. The aggregate region of the circumferentially spaced orifices 81 is larger than the region of the nozzle inlet 31, such that the velocity of the liquid passing through the orifices 81 is inversely proportional to the ratio of the size of the orifices 81 to the size of the nozzle inlet 31.

[0029]

[0033] More specifically, the circumferential orifice 81 at the downstream end of the expansion cavity 82 communicates with the inlet section 92 of the discharge passage 85, which is defined between the wall section 91 facing outward from the nozzle body 70 and the pintle 83 of the nozzle core 72. The cross-sectional area of ​​the annular inlet section 92 may increase as the section extends downstream, and as a result, the velocity of the fluid in this area continues to decrease as the cross-sectional area of ​​the discharge passage expands. A slight decrease in the cross-sectional area of ​​the discharge passage 85 in the subsequent stabilization section 93 of the discharge passage 85 immediately downstream of the inlet section 92 (also defined by the outer surface of the pintle 83 and the inner circumferential surface of the nozzle body 70) can provide a slight increase in pressure. This increase in pressure stabilizes and balances the inflow, removing individual jets caused by the fluid entering the inlet section 92 of the discharge passage 85 through a series of orifices 81, and allows for a uniform flow along the inner wall surface of the nozzle body 70. The cross-sectional region of the stabilization section 93 remains constant throughout this region when the fluid achieves stability.

[0030]

[0034] Downstream of the stabilization section 93, the liquid enters the final expansion section 95, defined by a tapered terminal section 90 inside the nozzle core 72, which extends downstream to a nozzle opening 94 formed at the downstream end of the nozzle body 70. The progressively increasing cross-sectional area of ​​the final expansion section 95 is achieved by decreasing the conical diameter of the pintle 83 of the terminal section 90, while the inner circumferential surface of the nozzle body 70 is maintained at a constant diameter. The pintle 83 helps to stabilize the fluid and allows for greater liquid expansion than could be achieved with a nozzle core having a simple uniform diameter. The sustained contact between the liquid and the inner and outer walls of the discharge passage is a function of the liquid's surface tension.

[0031]

[0035] The cross-sectional region of the final expansion section 95 at the nozzle opening 94 defines the exit velocity of the liquid, which is inversely proportional to the cross-sectional region at the nozzle opening 94 with respect to the region at the nozzle inlet 31. The terminal section 90 of the nozzle core 72 preferably extends slightly beyond the nozzle opening 94 to help break the surface tension of the liquid on the inner surface of the nozzle body 70 without affecting the outer diameter of the discharged liquid stream. Making the inner surface of the nozzle body 70 a constant diameter helps establish a constant diameter of the liquid boundary layer as the liquid exits the nozzle, which helps maintain the desired droplet diameter regardless of the distance of the nozzle from the target.

[0032]

[0036] A dramatic reduction in the velocity of the liquid can be achieved by progressively increasing the cross-sectional area of ​​the discharge passage 85. The inward expansion of the discharge passage 85 is achieved by gradually decreasing the diameter of the pintle 83 while maintaining the inner circumferential surface of the nozzle body 70. This helps to produce discharge liquid with a constant stream diameter. The reduction in the velocity of the liquid allows for distribution without splashing. This further allows for the distribution of liquid with a larger solid content by utilizing a larger nozzle inlet orifice 31. Once the discharge passage of the nozzle is initially filled with a viscous fluid, the surface tension of the liquid keeps the nozzle 30 filled with liquid ready to be discharged when the nozzle inlet 31 is opened. The liquid may be substantially incompressible so that a precise relationship can be maintained between the volume of liquid entering the nozzle 30 through the inlet 31 and the liquid exiting the nozzle opening 94. It has been found that circulating the piston 32 to open and close the inlet orifice 31 at a fast rate such as 50 milliseconds produces small, constant droplets of liquid, which are discharged at a reduced outlet velocity. This allows the released droplets to adhere to targets, such as those approximately 2 inches away from the nozzle, without scattering.

[0033]

[0037] From the above, it can be seen that a liquid distribution system is provided that can be selectively operated to distribute precisely controlled droplets without causing undesirable splashing of the distributed liquid. This system further includes a spray nozzle that is less susceptible to clogging due to the solid content of the liquid. However, the liquid distribution system and its liquid spray nozzle are relatively simple in design and suitable for economical manufacture and efficient use. Although the spray nozzle has been shown and described in relation to the exemplary liquid distribution system, it will be understood that the spray nozzle may be used in other applications for distributing controlled amounts of relatively small amounts of liquid.

Claims

1. In a spray nozzle assembly, A nozzle support body (20) having a liquid supply port (22) for coupling with a liquid supply, and further having an air supply port (50) for coupling with a pressurized air supply and air outlet port (52), A spray nozzle (30) is supported by the nozzle support body (20), The piston head (32a) is supported for movement within the opening (34) of the nozzle support body (20), and the downstream end of the piston (32) is selectively engageable with a spray nozzle liquid supply inlet (31) for controlling the inflow of liquid into the spray nozzle (30) and the discharge of liquid from the spray nozzle (30). A return spring (35) is supported inside a spring chamber (36) in the opening (34) of the nozzle support body upstream of the piston head (32a), and biases the piston (32) to the closed position of the liquid supply inlet of the spray nozzle. Equipped with, The opening (34) of the nozzle support body (20) defines a piston chamber (42) on the downstream side of the piston head (32a) opposite to the spring chamber (36), and the nozzle support body (20) has an air passage system that communicates with a control valve (43), and the control valve (43) is (1) In order to connect pressurized air from the air supply port (50) of the nozzle support body to the piston chamber (42), and to move the piston (32) against the biasing force of the return spring (35) to the spray nozzle liquid supply inlet opening position, thereby enabling the inflow of liquid into the spray nozzle (30) and the discharge of liquid from the spray nozzle (30), (2) A spray nozzle assembly that is selectively operable in order to prevent pressurized air from flowing from the nozzle support body air supply port (50) through the air passage system to the piston chamber (42), and to allow pressurized air from the piston chamber (42) to communicate with the nozzle support body air outlet port (52) via the spring chamber (36), thereby facilitating the return spring (35) to return the piston (32) to the spray nozzle liquid supply inlet closed position.

2. The spray nozzle assembly according to claim 1, wherein the control valve (43) has an air inlet port (55a), a work port (55c), and an exhaust port (55b), and is movable between (1) a first position in which the air inlet port (55a) is opened and pressurized air from the nozzle support body air supply port (50) is connected to the piston chamber (42) via the air inlet port (55a) and the work port (55c) to move the piston (32) to an open position, and (2) a second position in which the air inlet port (55a) is closed and pressurized air from the nozzle support body air supply port (50) is blocked via the air inlet port (55a) and pressurized air from the piston chamber (42) is connected to the nozzle support body air outlet port (52) via the spring chamber (36) via the work port (55c) and the exhaust port (55b).

3. The air passage system of the nozzle support body is A first air passage (63) connects pressurized air from the nozzle support body air supply port (50) to the control valve (43), A working passage (62) that connects pressurized air from the control valve (43) to the piston chamber (42), An outlet air passage (61) that connects pressurized air from the control valve (43) to the nozzle support body air outlet port (52) via the spring chamber (36), The spray nozzle assembly according to claim 1, comprising:

4. The control valve (43) has a valve mechanism (43a), and the control valve (43) is operable to move the valve mechanism (43a) between a first position and a second position, (1) the first position allows pressurized air from the air supply port (50) to communicate with the piston chamber (42) via the nozzle support body first air passage (63) and work passage (62), moving the piston (32) to the open position against the force of the return spring (35), and the outlet air passage (2) The second position is a position that blocks the communication of pressurized air to the passage (61), the spring chamber (36), and the air outlet port (52), and (3) the second position is a position that blocks the communication of pressurized air from the first air passage (63) to the work passage (62), and allows pressurized air from the piston chamber (42) to communicate with the spring chamber (36) and the air outlet port (52) via the work passage (62) and the outlet air passage (61), as described in claim 3.

5. The spray nozzle assembly according to claim 1, wherein the control valve is a solenoid valve.

6. The spray nozzle assembly according to claim 1, wherein the piston (32) is supported inside a piston carrier (33) which is sealed inside the nozzle support body opening (34), and the piston carrier (33) and piston head (32a) define the limits of the piston chamber (42) inside the opening (34) of the nozzle support body.

7. The spray nozzle assembly according to claim 4, wherein the return spring (35) is provided inside the retaining sleeve (37), and when the valve mechanism (43a) is in the second position, pressurized air communicating with the spring chamber (36) proceeds through the retaining sleeve (37) to the air outlet port (52).

8. The spray nozzle assembly according to claim 1, wherein the spray nozzle liquid supply inlet is the inlet (31) at the upstream end of the spray nozzle (30).

9. The spray nozzle assembly according to claim 1, comprising a plurality of nozzle support bodies, each having a control valve (43) and a spray nozzle (30).

10. The spray nozzle assembly according to claim 9, wherein the plurality of nozzle support bodies (20) are arranged side by side, with the liquid supply port (22), air supply port (50), and air outlet port (52) of each nozzle support body (20) being in fluid communication with the other respective liquid supply ports (22), air supply ports (50), and air discharge ports (52) of the other plurality of nozzle support bodies.

11. The spray nozzle includes a nozzle body having a substantially hollow cylindrical structure that defines an inner circumferential surface, and an internal nozzle core disposed inside the nozzle body. The spray nozzle assembly according to claim 1, wherein the internal nozzle core includes a teardrop-shaped pintle and an annular discharge passage, the teardrop-shaped pintle having an upstream end section adjacent to the upstream end wall of an expansion cavity, a radially outward curved section adjacent to the upstream end section, and a radially inward tapered conical end section, the annular discharge passage defined between the outer surface of the pintle and the inner circumferential surface of the nozzle body and in fluid communication with the expansion cavity of the nozzle seat.

12. The spray nozzle assembly according to claim 11, wherein the spray nozzle includes a nozzle seat having the liquid supply inlet and a downstream expansion cavity fluidly communicating with the liquid supply inlet, the expansion cavity terminates at a downstream end wall, and the annular discharge passage fluidly communicates with the expansion cavity.

13. In a liquid distribution system, The modular manifold comprises multiple individual liquid distribution modules (12) that are stacked and supported side by side in a sealed state, Each of the modules (12) is provided on an adjacent module (12) in a relationship aligned with a liquid supply port (21), and has a nozzle support body (20) in which a liquid supply port (21) is formed that defines a common liquid passage (22) communicating between the modules. The nozzle support body (20) of each module includes an air supply port (50) and an air outlet port (52) that communicate with the respective air supply ports (50) and air outlet ports (52) of adjacent modules. Each of the aforementioned modules (12) is, A spray nozzle (30) is supported by the nozzle support body (20), The piston head (32a) is supported for movement within the opening (34) of the nozzle support body (20), and the downstream end of the piston (32) is selectively engageable with a spray nozzle liquid supply inlet (31) for controlling the inflow of liquid into the spray nozzle (30) and the discharge of liquid from the spray nozzle (30). A return spring (35) is supported inside the spring chamber (36) in the nozzle support body opening (34) upstream of the piston head (32a) and biases the piston (32) to the spray nozzle liquid supply inlet closed position, Includes, The opening (34) of the nozzle support body (20) defines a piston chamber (42) on the downstream side of the piston head (32a) opposite to the spring chamber (36), The nozzle support body (20) has an air passage system that communicates with the control valve (43), A liquid distribution system that is selectively operable in order to (1) connect pressurized air from the air supply port (50) of the nozzle support body to the piston chamber (42), and move the piston (32) to the spray nozzle liquid supply inlet opening position against the biasing force of the return spring (35) to enable the inflow of liquid into the spray nozzle (30) and the discharge of liquid from the spray nozzle (30), and (2) prevent the inflow of pressurized air from the nozzle support body air supply port (50) to the piston chamber (42) through the air passage system, and connect pressurized air from the piston chamber (42) to the nozzle support body air outlet port (52) via the spring chamber (36) to facilitate the return of the piston (32) to the spray nozzle liquid supply inlet closed position by the biasing force of the return spring (35).

14. The liquid distribution system according to claim 13, wherein the air passage system of the nozzle support body (20) includes a first air passage (63) that connects pressurized air from the nozzle support body air supply port (50) to the control valve (43), a work passage (62) that connects pressurized air from the control valve (43) to the piston chamber (42), and an outlet air passage (61) that connects pressurized air from the spring chamber (36) to the nozzle support body air outlet port (52) via the piston chamber (42).

15. The control valve (43) has a valve mechanism (43a), and the control valve (43) is operable to move the valve mechanism (43a) between a first position and a second position, (1) the first position is to communicate pressurized air from the air supply port (50) to the piston chamber (42) via the nozzle support body first air passage (63) and work passage (62), to move the piston (32) to the open position against the force of the return spring (35), and the outlet air passage (61), (2) The second position is a position that blocks the communication of pressurized air to the spring chamber (36) and the air outlet port (52) of the nozzle support body, and (3) the second position is a position that blocks the communication of pressurized air from the first air passage (63) to the work passage (62), and allows pressurized air from the piston chamber (42) to communicate with the spring chamber (36) and the air outlet port (52) of the nozzle support body via the work passage (62) and the outlet air passage (61), as described in claim 14.

16. The liquid distribution system according to claim 13, wherein the spray nozzle includes a nozzle body having a substantially hollow cylindrical structure defining an inner circumferential surface, and an internal nozzle core disposed inside the nozzle body, the internal nozzle core includes a teardrop-shaped pintle and an annular discharge passage, the teardrop-shaped pintle having an upstream end section adjacent to the upstream end wall of an expansion cavity, a radially outward curved section adjacent to the upstream end section, and a radially inward tapered conical end section, the annular discharge passage is defined between the outer surface of the pintle and the inner circumferential surface of the nozzle body and is in fluid communication with the expansion cavity of the nozzle seat.

17. In a liquid distribution system, A modular manifold comprising a plurality of individual liquid distribution modules (12) stacked and supported side by side in a sealed state, a spray nozzle (30), and a return spring (35), Each module (12) is provided in a relationship aligned with the liquid supply port (21) of an adjacent module (12), and includes a nozzle support body (20) in which the liquid supply port (21) is formed, defining a common liquid passage (22) that communicates between the modules. The spray nozzle (30) is supported by the nozzle support body (20), The nozzle support body (20) of each module includes an air supply port (50) and an air outlet port (52) that communicate with the respective air supply ports (50) and air outlet ports (52) of the adjacent module (12). The spray nozzle (30) has a piston (32) having a piston head (32a), the piston head (32a) being supported for selected movement within the opening (34) of the nozzle support body (20), and controlling the flow of liquid for discharge from the spray nozzle (30). The opening (34) of the nozzle support body (20) defines a piston chamber (42) downstream of the piston head (32a), The return spring (35) is supported inside the spring chamber (36) within the opening (34) of the nozzle support body, and biases the piston (32) to the closed position of the spray nozzle liquid supply inlet. Each of the aforementioned modules (12) is, A nozzle body passage system including a control valve (43), a first air passage (63) that connects pressurized air from the air supply port (50) of the nozzle support body (20) to the control valve (43), a work passage (62) that connects pressurized air from the control valve (43) to the piston chamber (42), and an outlet air passage (61) that connects pressurized air from the control valve (43) to the air outlet port (52) of the nozzle support body (20) via the spring chamber (36), Includes, The control valve (43) has a valve mechanism (43a), and the control valve (43) is operable to move the valve mechanism (43a) between a first position and a second position, (1) the first position is such that pressurized air from the air supply port (50) is connected to the piston chamber (42) via the first air passage (63) and the work passage (62), and the piston (32) is moved to the open position against the force of the return spring (35), and in front of the nozzle support body (20) (1) The second position is a position that blocks communication of pressurized air to the outlet air passage (61), the spring chamber (36), and the outlet air passage (61), and (2) the second position is a position that blocks communication of pressurized air from the first air passage (63) to the work passage (62), and allows pressurized air from the piston chamber (42) to communicate with the spring chamber (36) and the air outlet port (52) of the nozzle support body via the work passage (62) and the outlet air passage (61), in a liquid distribution system.

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