Narrow-pointed electrostatic spray nozzle assembly and lubricant dispensing system

Abstract

A liquid dispensing system (10) for dispensing a highly viscous liquid, such as lubricating oil. The system (10) includes a nozzle body (20) and an elongate electrode (22) that define an annular liquid flow passage (46) in communication with a protruding, tapered configuration terminal end (40) of the electrode. The end cap of the nozzle body defines a plurality of circumferentially spaced discharge orifices (49a) around the electrode (22) for controlling discharge of charged liquid onto the terminal end of the electrode for guiding from the terminal end in a fine wire having a width of less than 0.1524 cm (0.06 inch).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 394,469, filed on August 2, 2022, which is incorporated by reference. Technical Field

[0002] The present invention relates generally to electrostatic spray nozzle assemblies and, more particularly, to lubrication systems for directing lubricant onto metal parts using such electrostatic spray nozzle assemblies. Background Art

[0003] Equipment in many industries has various components that must be continuously lubricated at very specific locations for continued proper operation. One such application is the canning industry, where unpainted aluminum cans are placed on the drive pins of a sprocket-driven chain conveyor that guides the cans through a decorating oven where they are painted and cured for their intended use. The decorating oven can reach internal temperatures of up to 200°C, where the lubricating oil for the chain rollers can evaporate, increasing the wear of the bearing pins. Without proper lubrication on the chain, the life expectancy of the chain is measured in days. In contrast, a properly lubricated chain can have a life expectancy of between 18 and 24 months. There is a constant need for technology to increase the life of such chain conveyors.

[0004] One of the most common methods of chain lubrication is a brush oiler. A brush is placed close to the passing chain so that it can sweep oil onto each component of the interior of the chain as the chain passes. However, this method is very messy, and if oil is splashed onto the interior of the can, the contaminated can must be discarded because the oil prevents proper coating.

[0005] Although electrostatic spray nozzles have been developed, they are not effective for spraying higher viscosity oils. Current trends in the industry indicate that companies are relying more heavily on higher viscosity oils for lubrication. High viscosity oils adhere to machine components longer, which helps extend the life of the equipment. This further enables less oil consumption to cope with rising production costs. In addition, when the electrostatic spray nozzle is operated with a reduced or minimum lubricant flow rate for sharp fine line discharge, the resulting gap or interruption in the lubricant supply can cause destructive arcing between the electrode and the metal component being sprayed.

[0006] In order to facilitate the atomization of such high viscosity liquids, electrostatic spray nozzle assemblies have utilized pressurized air-assisted atomization of the liquid. The problem with such pressurized air atomization designs is that they lack precision. The air atomization of the lubricant combined with electrostatics effectively turns the nozzle system into a spray system more similar to an electrostatic paint spray system. The problem with such a system is that the spray is essentially conical, and it is difficult to lubricate a relatively small target area without saturating the area outside the target. This results in wasteful overspray, adversely affects the working environment and requires difficult cleanup. Another disadvantage of such pressurized air atomization spray nozzle designs is that compressed air and compressed air systems are considerable costs to the user. Summary of the invention

[0007] It is an object of the present invention to provide an electrostatic spray nozzle assembly and dispensing system utilizing such a spray nozzle assembly that is more effective in accurately and reliably spraying fine lines of high viscosity liquids, such as oils and other lubricants, onto moving metal parts.

[0008] Another object is to provide an electrostatic spray system as hereinbefore characterized which operates without the need for pressurized air to assist atomization when breaking up a liquid into a fine particle discharge.

[0009] It is a further object to provide an electrostatic spray system of the foregoing type which is operable to direct a precise liquid spray pattern onto small moving targets without wasteful overspray which could harm the environment and result in expensive clean-up.

[0010] Yet another object is to provide an electrostatic lubricant dispensing system of the above kind in which the spray nozzle assembly precisely and reliably controls the discharge of lubricant in a manner for directing a very fine string or series of droplets without the possibility of arcing between the charging electrode and the metal object being coated.

[0011] Still another object is to provide an electrostatic spray nozzle assembly and lubricant dispensing system of the foregoing type which is relatively simple in design and which is suitable for economical and reliable use. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other objects and advantages of the present invention will become apparent upon reading the following detailed description and referring to the accompanying drawings, in which:

[0013] Figure 1 is a perspective view of an illustrated liquid dispensing system having a hydraulic electrostatic spray nozzle assembly according to the present invention for directing a high viscosity liquid such as oil or other lubricant onto a sprocket drive chain without pressurized air atomization of the liquid;

[0014] Figure 2yes Figure 1 a perspective view of an electrostatic spray nozzle assembly as shown in , wherein the terminal tip portion of the electrode is shown in an enlarged manner;

[0015] Figure 3 is an enlarged longitudinal section of the electrostatic spray nozzle assembly shown;

[0016] Figure 4 yes Figure 3 A side elevation view of the electrostatic spray nozzle assembly shown in; and

[0017] Figure 5 yes Figure 4 A downstream end view of the spray nozzle assembly is shown in FIG.

[0018] Although the present invention allows various modifications and alternative configurations, a certain exemplary embodiment of the present invention has been shown in the drawings and will be described in detail below. However, it should be understood that it is not intended to limit the present invention to the specific form disclosed, on the contrary, it is intended to cover all modifications, alternative configurations and equivalents that fall within the spirit and scope of the present invention. DETAILED DESCRIPTION

[0019] Now with more particular reference to the accompanying drawings Figure 1 , there is shown an exemplary liquid distribution system 10 having a hydraulic electrostatic spray nozzle assembly 11 according to the present invention, which is used to spray high viscosity liquids such as oils and other lubricants for specific directions and applications. For purposes herein, the term "hydraulic spray nozzle assembly" is intended to mean a spray nozzle assembly for spraying and directing liquids without pressurized air-assisted atomization and directing of the liquid. The illustrated distribution system 10 is designed to direct a thin string or series of droplets of high viscosity oil or other lubricant onto the pin and roller connection of a sprocket drive chain 12. Such a chain typically includes longitudinally spaced rollers 14 supported by corresponding pins 15, which in turn are connected by chain plates 16 on opposite sides of the rollers 14. It is essential that the connection between the pins 15 and the rollers 14 be lubricated for proper operation in many applications to prevent wear and chain failure.

[0020] The illustrated hydraulic electrostatic spray nozzle assembly 11 basically includes a nozzle body 20 having a downstream end in the form of an end cap 21 and an electrode 22 supported within the nozzle body 20 and extending through the nozzle body 20 and the end cap 21. The illustrated spray nozzle assembly 11 is supported by an L-shaped bracket 24 having vertical legs 24 for securing to a suitable mounting structure. a and a horizontal leg 24 having a central opening for supporting the nozzle body 20 b In this case, if Figures 2 to 4 As depicted in FIG. 1 , the nozzle body 20 includes an upstream section 28 of relatively small diameter, a middle section 29 of relatively large diameter, and a lower cylindrical section 30 of slightly smaller diameter than the middle section 29 and the bracket opening, with external threads. The middle section 29 of the nozzle body 20 is supported on the horizontal bracket legs 24. b 2, wherein the lower threaded section 30 depends from the bracket 24 and is fixed to the bracket 24 by a nut 31. In this example, the lower protruding end of the end cap 21 is formed with a flat portion 34 to facilitate wrench tightening and removal of the end cap 21. In this case, the end cap 21 has an upstream hub 35 with external threads, which is threadedly fixed with a threaded cavity in the downstream end of the nozzle body, as shown in FIG. Figure 3 It will be appreciated that although the nozzle body 20 and end cap 21 are shown as separate components, alternatively they may be integrally formed as a single component.

[0021] The electrode 22 has a generally cylindrical configuration having an upstream threaded section 38 ( Figure 3 ), a downstream cylindrical section 39 of smaller diameter extending through the nozzle body 20 and the end cap 21, and a downstream end 40 protruding from the end cap 21. The nozzle body 20 has a liquid inlet 42 on its side, which is connected to a liquid supply line 44 for communicating with a liquid supply such as a supply of high viscosity oil or other lubricant. The liquid inlet 42 communicates with the following: an annular passage 46 between the internal cylindrical chamber of the nozzle body 20 and the electrode 22, a downstream passage 48 between the electrode 22 and the upstream cylindrical chamber of the end cap 21, and a metering section 49 of the end cap 21 surrounding the protruding end 40 of the electrode ( Figure 2 and Figure 3 ).

[0022] In this example, the electrode 22 has an upstream end extending above the nozzle body 20, which is connected by a right angle fitting 50 to a high voltage cable 51 which is connected to a high voltage source such as a positive power supply ( Figure 1 ). In the event that the electrode 22 is charged by a high voltage power source, it will be seen that the liquid fed to the inlet 42 will be charged during its travel along the significant length of the electrode 22 through the nozzle body 20 and the end cap 21. In addition, the nozzle body 20 and the end cap 21 are made of insulating materials to allow the charge to be transferred only to the liquid as it is directed through the spray nozzle assembly 20.

[0023] In keeping with the important features of this embodiment, the end cap metering section 49 surrounding the protruding end of the electrode is formed by a plurality of relatively small circumferentially spaced metering orifices 49 in the end cap 21. a ( Figure 2) is defined for precisely controlling the discharge of fluid along the protruding end 40 of the electrode 22. In the illustrated embodiment, three circumferentially spaced metering orifices 49 a Provided in the downstream end of the end cap 21 for optimal guidance of the liquid along the protruding end 40 of the electrode 22 without excessive wasteful discharge or interruption of the liquid flow which could produce a harmful arc. The metering orifice 49 is shown a It has a half-moon-shaped structure, wherein the orifice 49 a The curved side portion of the electrode 22 extends radially outward from the circumferential wall of the end cap 21 surrounding the electrode 22, as shown in FIG. Figure 2 As depicted in. Metering orifice 49 a Designed to allow sufficient liquid to surround the terminal end 40 of the electrode 22 while restricting the flow for fine spot distribution and directing to specific target areas without gaps or inconsistencies in the discharge. It has been found that the electrostatic charge on the liquid causes the liquid to be drawn out of the orifice 49 faster than under normal pressure conditions. a The metering orifice 49a is relatively small in size, with the total opening or flow area of ​​the orifice being only about 0.0003 square inches. As depicted in the illustrated embodiment, it has been found that three such metering orifices 49a provide the best flow for completely surrounding the downstream end 40 of the electrode 22. Alternatively, two to six appropriately sized discharge orifices may be used to achieve good flow conditions where the total flow area is between 0.0002 and 0.0004 square inches.

[0024] Further in keeping with this embodiment, the protruding terminal end 40 of the electrode 22 is in the form of an acutely tapered tip designed to facilitate the flow of liquid from the circumferentially spaced metering orifices 49. a And the transition around the electrode terminal end 40 is used to guide the droplet with a pointed fine line or string. Although the tapered end 40 ( Figure 2 ) can be in the range of 10 to 30 degrees, but it has been found that, depending on the viscosity of the liquid, an angle of about 15 degrees provides optimal liquid guidance into thin lines of 0.06 inches or less in width.

[0025] In operation, it has been found that the liquid dispensing system is operable for such fine line targeted guidance of high viscosity liquids having a viscosity in the range of 150cP to 525cP, including lubricants and oils having a viscosity in the range of 75cP to 535cP. In the operation of the illustrated embodiment, the liquid enters the nozzle through the inlet 42 on the side of the body 11 and drips onto the electrode 22. Then, the liquid pours down along the electrode 22, acquiring a charge (free valence electron) from the electrode 22. When the liquid acquires a charge, the repulsive force destroys the surface tension of the fluid and allows the liquid to thin. This also serves to accelerate the liquid downward along the surface of the electrode. The highest point of energy transfer occurs at the tip end 40 (minimum cross-sectional area) of the electrode 22. The metering orifice 49a of the nozzle cap 21 is sized to allow just enough liquid to reach the tip end 40 of the electrode 22 for the applied high voltage while maintaining a controlled flow to the end 40. This also gives the liquid extra time to charge. Without such end cap control of the liquid, it has been found that charged liquid may exit the nozzle faster than the fluid entering the nozzle, potentially resulting in the electrode 22 being starved of insulating fluid, a condition that could result in destructive arcing between the electrode and the metal chain conveyor.

[0026] From the foregoing, it can be seen that a hydraulic electrostatic spray nozzle assembly and liquid dispensing system utilizing such a spray nozzle assembly is provided that can operate without pressurized air atomization for more reliably and efficiently directing a sharp, fine line of high viscosity liquid, such as oil or other lubricant, onto a specific target area. The system is operable to direct a precise liquid spray pattern onto a small, moving target without wasteful overspray that can harm the environment and result in expensive cleanup, and without the possibility of destructive arcing between an electrostatically charged electrode and the metal object being coated.

Claims

1. A liquid dispensing system for dispensing a high-viscosity liquid, comprising: A hydraulic electrostatic spray nozzle assembly, the hydraulic electrostatic spray nozzle assembly having a nozzle body; an elongated electrode supported within the nozzle body for coupling to an electrical power supply and having a terminal end projecting from the nozzle body in a downstream direction; a supply of a high viscosity liquid having a viscosity between 75 cP and 535 cP; The nozzle body and the elongated electrode define an annular liquid flow passage surrounding the electrode, the annular liquid flow passage communicating with a downstream terminal end of the electrode; the nozzle body having a liquid inlet coupled to a supply of the high viscosity liquid for directing the high viscosity liquid through the annular liquid flow passage between the electrode and the nozzle body for electrostatically charging the high viscosity liquid; and The nozzle body has a downstream end defining a plurality of circumferentially spaced metering orifices about the electrode for controlling discharge of electrostatically charged liquid onto the protruding terminal end of the electrode for directing therefrom in a thin line.

2. The liquid dispensing system according to claim 1, wherein: The circumferentially spaced metering orifices control the discharge of the high viscosity electrostatically charged liquid onto the terminal end of the electrode for discharge in an uninterrupted thin line.

3. The liquid dispensing system according to claim 2, wherein: The plurality of circumferentially spaced metering orifices controls the discharge of the electrostatically charged liquid in a thin line having a width of 0.06 inches or less.

4. The liquid dispensing system according to claim 1, wherein: The supply of highly viscous liquid is a supply of lubricant.

5. The liquid dispensing system according to claim 1, wherein: The supply of highly viscous liquid is a supply of oil.

6. The liquid dispensing system according to claim 1, wherein: The high viscosity liquid is directed through the annular flow passage and discharged from the spray nozzle assembly without pressurized air atomization.

7. The liquid dispensing system according to claim 1, wherein: The nozzle body includes a downstream end cap, and the end cap is formed with the circumferential metering orifice.

8. The liquid dispensing system according to claim 1, wherein: The nozzle body and the end cap are made of electrically insulating material.

9. The liquid dispensing system according to claim 1, wherein: The metering orifice extends outwardly from the electrode in a half-moon configuration.

10. The liquid dispensing system of claim 1, wherein: The metering orifice defines a total liquid flow area of ​​between 0.0002 and 0.0004 square inches onto the protruding end of the electrode.

11. The liquid dispensing system of claim 1, wherein: The protruding terminal end of the electrode is in the form of a tapered tip for diverting liquid from the circumferentially spaced metering orifices inwardly along the terminal end of the electrode for discharge of the high viscosity liquid in the thin line.

12. The liquid dispensing system of claim 1, wherein: The tapered tip of the electrode tapers inwardly at an angle of between 10 and 30 degrees in a downstream direction.

13. A lubricant dispensing system for dispensing, comprising: A hydraulic electrostatic spray nozzle assembly, the hydraulic electrostatic spray nozzle assembly having a nozzle body; an elongated electrode supported within the nozzle body for coupling to an electrical power supply and having a downstream terminal end portion of a conical configuration that tapers inwardly in a downstream direction projecting outwardly from the nozzle body; Oil supply; The nozzle body and the elongated electrode define an annular liquid flow passage surrounding the electrode, the annular liquid flow passage communicating with a downstream terminal end of the electrode; the nozzle body having a liquid inlet coupled to a liquid supply of the oil for directing oil through the annular liquid flow passage between the electrode and the nozzle body for electrostatically charging the oil; and The nozzle body has a downstream end defining a plurality of circumferentially spaced metering orifices about the electrode for controlling discharge of electrostatically charged oil onto the protruding terminal end of the electrode for directing therefrom in a thin line.

14. The lubricant dispensing system of claim 13, wherein: The plurality of circumferentially spaced metering orifices controls the discharge of the electrostatically charged oil in a thin line having a width of 0.06 inches or less.

15. The lubricant dispensing system of claim 13, wherein: The supply of oil has a viscosity between 75 cP and 535 cP.

16. The lubricant dispensing system of claim 13, wherein: The oil is directed through the annular flow passage and discharged from the spray nozzle assembly without pressurized air atomization.

17. The lubricant dispensing system of claim 13, wherein: The nozzle body includes a downstream end cap, and the end cap is formed with the circumferential metering orifice.

18. The lubricant dispensing system of claim 13, wherein: The metering orifice defines a total oil flow area of ​​between 0.0002 and 0.0004 square inches onto the protruding end of the electrode.

19. The lubricant dispensing system of claim 13, wherein: The tapered tip of the electrode tapers inwardly at an angle of between 10 and 30 degrees in a downstream direction.

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