Liquid dispensing system with liquid control piston operated by compressed air

Abstract

A modular liquid dispensing system in which each module has a module body, a spray nozzle (30) and a piston (32) for controlling dispensing of liquid from the nozzle (30). Each module has a pneumatic operating system for moving the piston (32) to an open position while facilitating a faster return motion to a closed position, thereby enabling dispensing of precisely controlled small droplet size quantities of highly viscous liquids.

Description

[0001] Cross-references to related applications

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 076,001, filed September 9, 2020, which is incorporated herein by reference. Technical Field

[0003] The present invention relates to liquid dispensing systems, and more particularly to liquid dispensing systems having nozzles for dispensing small controlled amounts of highly viscous liquids. Background Technology

[0004] In many industries, there is a need to dispense small, controlled amounts of highly viscous liquids. In the food industry, for example, in the commercial production of pizza, small droplets of sauce need to be dispensed onto the pizza dough. Due to the viscous nature of the sauce, it is difficult to dispense precisely controlled droplets as quickly as desired. Furthermore, if the sauce contains solids that can clog the nozzle channels, the flow channels must be made larger, making it even more difficult to control the distribution of small droplets and often resulting in undesirable splattering of the dispensed sauce. Additionally, when the dispensing device uses an air-operated liquid control piston, the rapid operation of the piston is limited by the compressibility of the control air. Moreover, when the air-operated device is spring-returned, the spring return force can be limited to approximately half the air pressure used to open the device, which hinders the rapid closing of the piston. Summary of the Invention

[0005] Purpose and Overview of the Invention

[0006] One object of the present invention is to provide a liquid dispensing system having a spray nozzle that effectively dispenses highly viscous liquid in precisely controlled amounts of small droplet sizes.

[0007] Another objective is to provide a liquid dispensing system as described above, which efficiently and rapidly deposits precisely controlled pixel-sized droplets without undesirable liquid splashing.

[0008] Another objective is to provide a liquid dispensing system of the type described above, wherein the spray nozzle can be operated through a larger inlet channel that is less likely to be blocked by solid inclusions in the liquid.

[0009] Another objective is to provide a liquid dispensing system that can selectively operate to dispense precisely controlled droplets of different sizes.

[0010] Another objective is to provide a liquid dispensing system that operates more quickly.

[0011] Another objective is to provide a liquid dispensing system having an air-actuated piston with a return spring, the function of which is to provide less resistance to the air pressure used in the operating system.

[0012] Another objective is to provide a liquid distribution system of the aforementioned type that is relatively simple in design and facilitates economical manufacturing and efficient use.

[0013] Other objects and advantages of the invention will become apparent from reading the following detailed description and referring to the accompanying drawings. Attached Figure Description

[0014] Figure 1 This is a partial perspective view of a liquid distribution system with an illustrative modular construction according to the present invention;

[0015] Figure 2 This is a perspective view of the fully assembled liquid distribution system;

[0016] Figure 3 This is a vertical cross-section of a liquid distribution module of the liquid distribution system shown.

[0017] Figure 4 yes Figure 3 An enlarged vertical cross-section of the central liquid control piston assembly of the liquid distribution module shown.

[0018] Figure 5 This is an enlarged perspective view of the vertical cross-section of the spray nozzle assembly of a liquid distribution module in the system shown.

[0019] Figure 6 yes Figure 5 The vertical cross-section of the spray nozzle assembly shown;

[0020] Figure 7 yes Figure 5 and 6 An exploded perspective view of the spray nozzle assembly shown; and

[0021] Figure 8 This is a schematic depiction of the solenoid control valve associated with each corresponding liquid distribution module.

[0022] While the invention may have various modifications and alternative constructions, specific illustrative embodiments thereof have been shown in the accompanying drawings and will be described in detail below. However, it should be understood that the invention is not intended to be limited to the specific forms disclosed, but rather, it is intended to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention. Detailed Implementation

[0023] Now, please refer more specifically to the attached diagram. Figure 1-3An illustrative liquid dispensing system 10 according to the present invention is shown. The illustrated liquid dispensing system 10 is in the form of a modular valve manifold 11, comprising a plurality of individual liquid dispensing modules 12 supported and held between end blocks 13 and 14 in a sealed side-by-side stacked relationship, the end blocks 13 and 14 being secured together at opposite ends by a pull rod 15 and a nut 16. Each module 12 includes a module nozzle support body 20 forming a liquid supply port 21 aligned with the liquid supply ports 21 of adjacent modules 12, defining a common liquid supply channel 22 communicating between a liquid inlet port 23 in the upstream end block 13 and a liquid outlet port 24 in the downstream end block 14. Thus, liquid guided to the inlet 23 communicates through each stacked module 12.

[0024] Each illustrated module 12 has a corresponding spray nozzle 30, which is mounted in a suspended manner to the underside of a module nozzle support body 20, the module nozzle support body 20 having an upstream liquid inlet 31 communicating with a liquid supply channel 22 on its upper side. To control the liquid flow from the common liquid supply channel 22 to the spray nozzle inlet 31 of the module 12, a piston 32 is supported above the spray nozzle inlet 31 in each module body 20 for reciprocating movement between an elevated inlet open position and a lowered inlet closed position.

[0025] In this configuration, each piston 32 is supported for selective relative movement within a bracket 33, which is fitted in a sealing relationship within a vertical opening 34 of the corresponding module body 20. The downstream end of the piston 32 extends through a liquid supply passage 22 to engage with a spray nozzle inlet 31. To bias the piston 32 into a lowered position with the spray nozzle inlet 31 closed, a return spring 35 is disposed within a spring chamber 36 of the module body 20, inserted between the head 32a of the piston 32 and a retaining sleeve 37, which is fixed within the upper end of the body opening 34 and held by a retaining cap 38 threadedly engaged within the upper end of the body opening 34. In this configuration, the retaining sleeve 37 extends downward around the return spring 35 and the piston head 32a, as... Figure 3 and 4 Best depicted. In this case, the opening 34 of the spring retaining sleeve 37 and the module body 20 defines an annular airflow channel 40 surrounding the retaining sleeve 37. Figure 3 The channel communicates with and passes through the spring chamber 36 via a circumferentially biased hole 41 in the spring retaining sleeve 37. A sealed piston chamber 42 is defined between the piston head 32a and the opposing axial ends of the bracket 42. Figure 4 ).

[0026] According to a key feature of this embodiment, each module body has a pressurized air passage system controlled by a corresponding valve, such that the pressurized air moving the piston to the open position further enhances the piston's rapid movement to the closed position. In the illustrated embodiment, the operation of the piston 32 of each module 12 between the open and closed positions is controlled by a corresponding solenoid valve 43, such as... Figure 3 and 8 The best depiction is as follows. Each module solenoid valve 43 is attached to its corresponding module body 20, and the solenoid mounting block 44 is mounted to its corresponding module body 20 in a sealing relationship 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 to define a common gas inlet passage communicating with the system air inlet port 51 in the end block 14. Each module body 20 also has an air outlet port 52 aligned to define a common air outlet passage communicating with the 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 through the inlet air passages 63, 63a in the module body 20 and the solenoid mounting block 44. The air outlet port 52 of the module body 20 communicates with the return spring chamber 36 via the outlet channel 60 through the hole 41 in the retaining sleeve 37 and the annular channel 40 around the sleeve 37. The outlet channels 61 and 61a in the module body 20 and the solenoid mounting block 44 communicate with the exhaust port 55b of the solenoid valve 43. The piston chamber 42 communicates with the working port 55c of the solenoid control valve 43 via the working channels 62 and 62a in the module body 20 and the solenoid mounting block 44.

[0027] When the solenoid valve 43 is in its natural or unexcited state under these conditions, the inlet pressure at the air inlet 55a of the solenoid valve port is controlled by the solenoid valve 43 ( Figure 8 The mechanism 43a (in the form of a rod in this case) blocks the pressurized air at the air supply port 50 of the module body 20, thereby preventing communication between the pressurized air at the air supply port 50 of the module body 20 and the piston chamber 42 via the solenoid mounting block 44 and the channels 62a, 62 in the module body 20. When the solenoid valve 43 is in its natural or unexcited state, an additional channel route connects the ports 55c, 55b of the solenoid valve 43, thereby allowing air between the piston chamber 42 and the outlet port 52 in the module body 20 to communicate via the channels 62, 62a in the module body 20 and the solenoid mounting block 44 and the outlet channels 61a, 61 in the solenoid mounting block 44 and the module body 20, via the hole 41 through the annular channel 40 around the spring 35 and the outlet channel 60.

[0028] When the solenoid valve 43 is actuated, the solenoid movement actuator 43a closes the exhaust port 55b, thereby removing the connection of port 55c to the atmosphere and connecting the solenoid valve ports 55a and 55c. Pressurized air at the air supply port 50 of the module body 20 then communicates with the pressure chamber 42 via channels 63 and 63a, solenoid valve ports 55a and 55c, and channels 62a and 62 in the module body 20 and the solenoid mounting block 44, causing the piston 32 to stroke upward, thereby opening the nozzle inlet 31 and compressing the return spring 35. The upward stroke of the piston head 32a imparts a positive air displacement within the spring chamber 36, resulting in a slight increase in pressure. The increased pressure in the spring chamber 36 is discharged to atmospheric pressure through the orifice 41 in the spring retaining sleeve 37, the annular channel 40, the outlet channel 60, and the air outlet port 52. Figure 3 and 4 When the solenoid is energized, the nozzle inlet 31 remains open, thereby allowing liquid to flow from the common liquid supply channel 22 through the spray nozzle 30 into the atmosphere.

[0029] When de-energized, solenoid valve 43 moves back to its natural state. The inlet air pressure at solenoid port 55a is blocked again, preventing pressurized air from entering the device. When the system pressure in piston chamber 42 is released and equalized with atmospheric pressure, the rapid decompression of the pressurized air in piston chamber 42 causes high pressure migration in channels 62, 62a in module body 20 and solenoid mounting block 44, ports 55c and 55b of solenoid valve 43, outlet channels 61a and 61 in solenoid mounting block 44 and module body 20, spring chamber 36, outlet channel 60, and outlet port 52. The migrating pressure in the annular channel 40 communicates through the hole 41 in the spring retaining sleeve 37, causing a pressure increase within the spring chamber 36. This pressure acts on the surface area of ​​the piston head 32a within the spring chamber 36, generating a momentary downward force that complements the constant downward force from the return spring 35. This force resists the decompression pressure in the piston chamber 42, returning the piston 32 to its natural state, closing the channel 31, and stopping the flow of liquid from the common liquid supply channel 22 through the spray nozzle 30. The significant reduction in the time required for the piston 32 to return to its natural state is attributed to the momentary increase in pressure within the spring chamber 36. All channels and chambers downstream of the solenoid valve 43, including the spring chamber 36, essentially return to atmospheric pressure through the outlet port 52, effectively removing the supplementary force of the momentary pressure applied to the piston head 32a.

[0030] By re-energizing the solenoid 43, further operation of the liquid dispensing module 12 is unaffected by the increased pressure from the previous cycle in the spring chamber 36, because the increased pressure is instantaneous and quickly returns to atmospheric pressure. This allows the increased pressure to have the desired effect on the opening stroke of the piston 32 without affecting its closing stroke. As will be apparent, for a given dispensing operation, the solenoid valve 43 can cycle at a predetermined rate, and the variable opening time of the piston 32 provides varying pixel volume.

[0031] According to another aspect of this embodiment, even when the liquid has a considerable amount of solid inclusions, each spray nozzle module 12 can be operated to dispense controlled, small, circular pixel-sized, highly viscous liquid droplets in conjunction with the piston 32. See in particular... Figure 5 , 6 In configuration 7, each spray nozzle 30 includes a nozzle body 70, a nozzle seat 71, and an internal nozzle core 72. In this configuration, the nozzle seat 71 has an externally threaded cylindrical downstream end 73 that threadedly engages within the upstream cylindrical end 74 of the nozzle body 70 to secure the nozzle core 92 within the nozzle body 70. The upstream end 75 of the nozzle seat 71 defines a predetermined liquid inlet 31 located at the upstream end of the assembly. In this configuration, the nozzle core 72 has an upstream cylindrical mounting flange 78 positioned on an annular crossbar 79 within the nozzle body 70 and held in place by the nozzle seat 71; however, it will be understood that other methods can be used to secure the nozzle core 72 within the nozzle body 70.

[0032] The cylindrical mounting flange 78 of the core 72 has a concave downstream end wall 80 (relative to the fluid flow direction) forming a plurality of circumferentially spaced, axially oriented liquid orifices 81. These liquid orifices communicate between the enlarged cavity 82 of the nozzle seat 71 and a liquid discharge channel defined by an annular structure between the nozzle core 72 and the nozzle body 70, for the purpose of guiding the liquid in a controlled manner for optimal distribution in the form of small droplets, as will become apparent. It should be understood that although the illustrated nozzle 30 comprises multiple components, alternatively, it may have a single-piece structure or fewer or more assembled parts.

[0033] In implementing this aspect of the embodiment, the nozzle core 72 has a teardrop-shaped pivot 83 that, together with the inner circumferential surface of the surrounding nozzle body 70, defines an enlarged discharge channel 85. This discharge channel 85 reduces the discharge velocity of the dispensed liquid to maintain the desired flow rate and consistent droplet size of the high-viscosity discharged liquid. For this purpose, the illustrated pivot 83 (see...) Figure 5 , 67) has an upstream end section 86 of relatively small diameter extending from the center of the mounting flange 78, a radially outwardly extending curved section 87 adjacent to the upstream end, and a relatively long conical end section 90 that tapers inwardly. As described above, the nozzle body 70 has a generally hollow cylindrical construction, wherein the inner circumferential surface of the nozzle body 70 defines the outer wall of an annular discharge channel 85 surrounding the core section 72. The inner wall of the discharge channel 85 is defined by the outer surface of the pivot 83. In this case, the inner circumferential surface of the nozzle body 70 includes a radially outwardly pointing section 91 and a uniform diameter section 84, which extends around the outwardly curved section 87 of the nozzle core 72, and the uniform diameter section 84 then extends substantially downstream for the remaining length of the pivot 83. The unique feature of this design is that the flow through the annular discharge channel enables the inward expansion of the viscous liquid as it travels through the nozzle body. The geometry of the pivot defines the inner diameter wall of the annular flow path, while also providing a structure against which a vacuum can be formed due to flow expansion. The deceleration of the liquid within the expanded annular discharge channel is a function of surface tension and capillary forces, enhancing the ability to create a vacuum and impede flow.

[0034] Continue to refer to Figure 3 In operation, when piston 32 is in the raised inlet-open position, liquid is allowed to enter in a controlled manner through nozzle inlet 31 into an expansion chamber 82 defined within the cylindrical downstream end of nozzle seat 71. Liquid passing through nozzle inlet 31 is directed to an impact surface defined by the concave downstream end wall 80 of expansion chamber 82. This causes liquid to fill expansion chamber 82 and then be forced from expansion chamber into discharge channel 85 through a series of circumferentially spaced orifices 81. Furthermore, each orifice 81 is at least as large as nozzle inlet 31 to allow solid particles in the liquid to flow from expansion chamber 82 to fluid discharge channel 85 without clogging. The total area of ​​the circumferentially spaced orifices 81 is greater than the area of ​​nozzle inlet 31, such that the velocity of liquid through orifices 81 is inversely proportional to the ratio of the size of orifice 81 to the size of nozzle inlet 31.

[0035] More specifically, the circumferential orifice 81 at the downstream end of the enlarged cavity 82 communicates with the inlet section 92 of the discharge channel 85, which is defined between the outwardly pointing wall section 91 of the nozzle body 70 and the pivot 83 of the nozzle core 72. The cross-sectional area of ​​the annular inlet section 92 can increase as the section extends downstream, such that the fluid velocity in this region continues to decrease as the cross-sectional area of ​​the discharge channel expands. In the subsequent stabilizing section 93 of the discharge channel 85 immediately downstream of the inlet section 92 (also defined by the outer surface of the pivot 83 and the inner circumferential surface of the nozzle body 70), the slight decrease in the cross-sectional area of ​​the discharge channel 85 can provide a slight increase in pressure. This increase in pressure stabilizes and balances the flow of individual jets caused by the fluid entering the inlet section 92 of the discharge channel 85 through a series of orifices 81, and allows for uniform flow along the inner wall surface of the nozzle body 70. As the fluid gains stability, the cross-sectional area of ​​the stabilizing section 93 remains constant throughout the region.

[0036] Downstream of the stabilizing section 93, the liquid enters the final expanding section 95, defined by the inwardly tapering terminal section 90 of the nozzle core 72, which extends downstream to the nozzle orifice 94 defined at the downstream end of the nozzle body 70. The gradually increasing cross-sectional area of ​​the final expanding section 95 is achieved by reducing the conical diameter of the pivot 83 in the terminal section 90, while the inner circumferential surface of the nozzle body 70 remains at a uniform diameter. The pivot 83 helps stabilize the fluid and enables greater liquid expansion compared to that achievable with a nozzle core having a simple, uniform diameter. The continuous contact between the liquid and the inner and outer surfaces of the discharge channel is a function of the liquid surface tension.

[0037] The cross-sectional area of ​​the final enlarged section 95 at the nozzle orifice 94 defines the liquid discharge velocity, which is inversely proportional to the cross-sectional area of ​​the nozzle orifice 94 relative to the area of ​​the nozzle inlet 31. The terminal section 90 of the nozzle core 72 preferably extends slightly beyond the nozzle orifice 94 to help break the surface tension between the liquid and the inner circumferential surface of the nozzle body 70 without affecting the outer diameter of the discharged liquid flow. Maintaining a constant diameter on the inner circumferential surface of the nozzle body 70 helps establish a consistent liquid boundary layer diameter as the liquid exits the nozzle, which helps maintain the desired droplet diameter, regardless of the distance of the nozzle from the target.

[0038] It has been found that a significant reduction in liquid velocity can be achieved by gradually increasing the cross-sectional area of ​​the discharge channel 85. The inward expansion of the discharge channel 85 is achieved by gradually decreasing the diameter of the pivot 83 while maintaining the inner circumferential surface of the nozzle body 70. This contributes to producing a discharge liquid with a consistent flow diameter. The reduction in liquid velocity allows it to be dispensed without splashing. This further allows for the use of a larger nozzle inlet orifice 31 to enable the dispensing of liquids with larger solid contents. Once the nozzle's discharge channel is initially filled with a viscous fluid, the surface tension of the liquid keeps the nozzle 30 filled with liquid, ready for dispensing when the nozzle inlet 31 opens. Because the liquid can be substantially incompressible, a precise relationship can be maintained between the volume of liquid entering the nozzle 30 through inlet 31 and the volume of liquid exiting the nozzle orifice 94. It has been found that rapidly opening and closing the inlet orifice 31 by circulating the piston 32 (e.g., 50 milliseconds) produces small, consistent droplets discharged at a reduced exit velocity. This allows the discharged droplets to deposit on targets, such as those approximately 2 inches from the nozzle, without splashing.

[0039] As can be seen from the above, a liquid dispensing system is provided that can be selectively operated to dispense precisely controlled droplets without causing undesirable splashing of the dispensed liquid. The system also includes a spray nozzle that is not easily clogged by solid inclusions in the liquid. However, the liquid dispensing system and its liquid spray nozzle are relatively simple in design and contribute to economical manufacturing and efficient use. While the spray nozzle has been shown and described in conjunction with the illustrative liquid dispensing system, it will be understood that the spray nozzle can be used in other applications to dispense controlled, relatively small amounts of liquid.

Claims

1. A spray nozzle assembly, comprising: The nozzle support body (20) has a liquid supply port (22) for connection to a liquid supply, and the nozzle support body (20) also has an air supply port (50) for connection to a pressurized air supply and an air outlet port (52). A spray nozzle (30) supported by the nozzle support body (20); A piston (32) having a piston head (32a) supported to move in an opening (34) of the nozzle support body (20), the downstream end of the piston (32) selectively engaging with a liquid supply inlet (31) of the spray nozzle to control the flow of liquid to and from the spray nozzle (30). A return spring (35), which is supported on the upstream side of the piston head (32a) in a spring chamber (36) in the opening (34) of the nozzle support body, is used to bias the piston (32) to the closed position of the liquid supply inlet of the spray nozzle. The opening (34) of the nozzle support body 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 connected to the control valve (43). The control valve (43) operates selectively to connect pressurized air from the air supply port (50) of the nozzle support body to the piston chamber (42), to move the piston (32) to the open position of the liquid supply inlet of the spray nozzle against the bias force of the return spring (35), and to allow liquid to flow to and from the spray nozzle (30). Alternatively, it can be used to prevent pressurized air from flowing through the air channel system from the air supply port (50) of the nozzle support body to the piston chamber (42), while allowing the pressurized air that is last guided to the piston chamber to communicate with the spring chamber (36) before being guided to the air outlet port (52) of the nozzle support body, so as to cause an increased pressure acting on the piston head (32a) in the spring chamber (36), thereby generating an instantaneous force that supplements the bias force of the return spring (35) when moving the piston toward the closed position of the liquid supply inlet of the spray nozzle.

2. The spray nozzle assembly according to claim 1, wherein, The control valve (43) has an inlet port (55a), a working port (55c), an exhaust port (55b), and a valve actuation mechanism (43a) that moves between a first position with the inlet port (55a) open and a second position with the inlet port (55a) closed. The first position allows pressurized air to flow from the air supply port (50) of the nozzle support body through the inlet port (55a) and the working port (55c) to the piston chamber (42) to move the piston (32) to the open position. The second position prevents pressurized air from flowing from the air supply port (50) of the nozzle support body through the inlet port (55a) while opening the exhaust port (55b) to allow pressurized air to flow from the piston chamber (42) through the working port (55c) and the exhaust port (55b) to the spring chamber (36) and through the spring chamber (36) to the air outlet port (52) of the nozzle support body.

3. The spray nozzle assembly according to claim 1, wherein, The air passage system of the nozzle support body includes: a first air passage (63) for connecting pressurized air from the air supply port (50) of the nozzle support body to the control valve (43); a working passage (62) for connecting pressurized air from the control valve (43) to the piston chamber (42); and an outlet air passage (61) for connecting pressurized air from the control valve (43) to the piston chamber (42) and through the piston chamber (42) to the air outlet port (52) of the nozzle support body.

4. The spray nozzle assembly according to claim 3, wherein, The control valve (43) has a valve actuation mechanism (43a); and the control valve (43) is operated to move the valve actuation mechanism (43a) between a first position and a second position, the first position allowing pressurized air to communicate from the air supply port (50) through the first air passage (63) and the working passage (62) of the nozzle support body to the piston chamber (42) to move the piston (32) against the force of the return spring (35) to the open position, while preventing pressurized air from communicating with the outlet air passage (61), the spring chamber (36) and the air outlet port (52) of the nozzle support body, the second position preventing pressurized air from communicating from the first air passage (63) to the working passage (62), while allowing pressurized air to communicate from the piston chamber (42) through the working passage (62) and the outlet air passage (61) to the spring chamber (36) and through the spring chamber (36) to the air outlet port (52) of the nozzle support body.

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 in a piston bracket (33), which is installed in a sealed relationship in the opening (34) of the nozzle support body; and the piston bracket (33) and the piston head (32a) define the limit of the piston chamber (42) in the opening (34) of the nozzle support body.

7. The spray nozzle assembly according to claim 4, wherein, The reset spring (35) is disposed in the retaining sleeve (37), and when the valve actuation mechanism (43a) is in the second position, pressurized air surrounds the piston chamber (42) and passes through the retaining sleeve (37) to communicate with the air outlet port (52) of the nozzle support body.

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

9. The spray nozzle assembly according to claim 1, comprising a plurality of the nozzle support bodies, each of the nozzle support bodies having a corresponding one of the control valve (43) and the 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 relative to each other, and the liquid supply port (22), air supply port (50) and air outlet port (52) of each nozzle support body (20) are in fluid communication with the corresponding liquid supply port (22), air supply port (50) and air outlet port (52) of another of the plurality of nozzle support bodies.

11. The spray nozzle assembly according to claim 1, wherein, The spray nozzle includes a nozzle body having a generally hollow cylindrical structure defining an inner circumferential surface; and an internal nozzle core disposed within the nozzle body and including a teardrop-shaped pivot having an upstream end section adjacent to an upstream end wall of an expansion cavity, a radially outwardly curved section adjacent to the upstream end section, and a radially inwardly tapering conical end section. An annular discharge channel is defined between the outer surface of the pivot and the inner circumferential surface of the nozzle body, the annular discharge channel being in fluid communication with the expansion cavity.

12. The spray nozzle assembly of claim 11, wherein, The spray nozzle includes a nozzle seat having a liquid supply inlet for the spray nozzle and an enlarged cavity in fluid communication with the liquid supply inlet for the spray nozzle, the enlarged cavity terminating at a downstream end wall.

13. A liquid dispensing system, comprising: Modular manifold, which has multiple individual liquid dispensing modules (12) supported by a sealed, side-by-side stacked relationship. Each of the modules (12) includes a nozzle support body (20), which has a liquid supply port (22) aligned with the liquid supply port (22) on the adjacent module (12) to define a common liquid channel connecting the modules. The nozzle support body (20) of each module includes an air supply port (50) and an air outlet port (52), which are connected to the corresponding air supply port (50) and air outlet port (52) of the adjacent module. Each of the modules (12) includes: A spray nozzle (30) supported by the nozzle support body (20); A piston (32) having a piston head (32a) supported to move in an opening (34) of the nozzle support body (20), the downstream end of the piston (32) selectively engaging with a liquid supply inlet (31) of a spray nozzle to control the flow of liquid to and from the spray nozzle (30). A return spring (35), which is supported on the upstream side of the piston head (32a) in a spring chamber (36) in the opening (34) of the nozzle support body, is used to bias the piston (32) to the closed position of the liquid supply inlet of the spray nozzle. The opening (34) of the nozzle support body 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 connected to the control valve (43). The control valve (43) operates selectively: to allow pressurized air to flow from the air supply port (50) of the nozzle support body to the piston chamber (42), to move the piston (32) to the open position of the liquid supply inlet of the spray nozzle against the biasing force of the return spring (35), to allow liquid to flow to and from the spray nozzle (30); or to prevent pressurized air from flowing from the air supply port (50) of the nozzle support body to the piston chamber (42) through the air passage system, while allowing the pressurized air last guided to the piston chamber to flow from the piston chamber (42) to the spring chamber (36) and through the spring chamber (36) before being guided to the air outlet port (52) of the nozzle support body, so as to cause an increased pressure acting on the piston head (32a) in the spring chamber (36), thereby generating an instantaneous force that supplements the biasing force of the return spring (35) when moving the piston (32) toward the closed position of the spray nozzle inlet.

14. The liquid dispensing system according to claim 13, wherein, The air passage system of the nozzle support body includes a first air passage (63) for connecting pressurized air from the air supply port (50) of the nozzle support body to the control valve (43), a working passage (62) for connecting pressurized air from the control valve (43) to the piston chamber (42), and an outlet air passage (61) for connecting pressurized air from the control valve (43) to the piston chamber (42) and through the piston chamber (42) to the air outlet port (52) of the nozzle support body.

15. The liquid dispensing system according to claim 14, wherein, The control valve (43) has a valve actuation mechanism (43a); and the control valve (43) is operated to move the valve actuation mechanism (43a) between a first position and a second position, wherein the first position allows pressurized air to communicate from the air supply port (50) through the first air passage (63) and the working passage (62) of the nozzle support body to the piston chamber (42), for moving the piston (32) against the force of the return spring (35) to the open position, while preventing pressurized air from communicating with the outlet air passage (61) of the nozzle support body, the spring chamber (36) and the air outlet port (52) of the nozzle support body, and the second position prevents pressurized air from communicating from the first air passage (63) to the working passage (62), while allowing pressurized air to communicate from the piston chamber (42) through the working passage (62) and the outlet air passage (61) to the spring chamber (36) and through the spring chamber (36) to the air outlet port (52) of the nozzle support body.

16. The liquid dispensing system according to claim 15, wherein, The reset spring (35) is disposed in the retaining sleeve (37), and when the valve actuation mechanism (43a) is in the second position, pressurized air flows from the piston chamber (42) around and through the retaining sleeve (37) to the air outlet port (52) of the nozzle support body.

17. The liquid dispensing system according to claim 13, wherein, The spray nozzle includes a nozzle body having a generally hollow cylindrical structure defining an inner circumferential surface; and an internal nozzle core disposed within the nozzle body and including a teardrop-shaped pivot having an upstream end section adjacent to an upstream end wall of an enlarged cavity of a nozzle seat, a radially outwardly curved section adjacent to the upstream end section, and a radially inwardly tapering conical terminal section. An annular discharge channel is defined between an outer surface of the pivot and an inner circumferential surface of the nozzle body, the annular discharge channel being in fluid communication with the enlarged cavity of the nozzle seat.

18. A liquid dispensing system, comprising: Modular manifold with multiple individual liquid dispensing modules (12) supported by a sealed side-by-side stacked relationship. Each of the modules (12) includes a nozzle support body (20) having a liquid supply port (22) aligned with a liquid supply port (22) on an adjacent module (12) for defining a common liquid channel connecting the modules. The nozzle support body (20) of each module includes an air supply port (50) and an air outlet port (52), which are connected to the corresponding air supply port (50) and air outlet port (52) of the adjacent module. Each of the modules includes: The control valve (43) and nozzle body channel system include a first air channel (63) for connecting pressurized air from the air supply port (50) of the nozzle support body to the control valve (43), a working channel (62) for connecting pressurized air from the control valve (43) to the piston chamber (42), and an outlet air channel (61) for connecting pressurized air from the control valve (43) to the spring chamber (36) and through the spring chamber (36) to the air outlet port (52) of the nozzle support body. The control valve (43) has a valve actuation mechanism (43a), and the control valve (43) is operated to move the valve actuation mechanism (43a) between a first position and a second position. The first position allows pressurized air to communicate from the air supply port (50) through a first air passage (63) and a working passage (62) of the nozzle support body to the piston chamber (42) to move the piston (32) to the open position against the force of the return spring (35), while preventing pressurized air from communicating with the outlet air passage (61), spring chamber (36), and air outlet port (52) of the nozzle support body. The second position prevents pressurized air from communicating with the nozzle support body. Air is connected from the first air passage (63) to the working passage (62) and then to the piston chamber. At the same time, the pressurized air that has been guided into the piston chamber is connected from the piston chamber (42) through the working passage (62) and the outlet air passage (61) to the spring chamber (36) and through the spring chamber (36) before leaving the air outlet port (52) of the nozzle support body. This causes an increased pressure acting on the piston head (32a) in the spring chamber (36), thereby generating an instantaneous force that supplements the force of the return spring (35) when moving the piston (32) toward the closed position of the liquid supply inlet of the spray nozzle.

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