Narrow Point Electrostatic Spray Nozzle Assembly and Lubricant Distribution System

Abstract

A liquid dispensing system (10) for dispensing a highly viscous liquid such as a lubricating oil. The system (10) includes a nozzle body (20) and an elongated electrode (22) that define an annular liquid flow path (46) that communicates with a conically configured end (40) of the electrode that protrudes. The end cap of the nozzle body defines a plurality of discharge orifices (49a) circumferentially spaced around the electrode (22) and controls the discharge of the charged liquid to the end of the electrode for guiding in a thin line having a width of less than 0.1524 cm (0.06 inches) from the electrode.

Description

Technical Field

[0001] (Cross - Reference to Related Applications)

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 394,469, filed Aug. 2, 2022, and incorporates it by reference.

[0002] (Technical Field)

[0002] The present invention generally relates to an electrostatic spray nozzle assembly, and more particularly to a lubrication system for guiding a lubricant onto a metal part by use of such an electrostatic spray nozzle assembly.

Background Art

[0003] (Background Art)

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

[0004]

[0004] One of the most common methods of chain lubrication is the brush - type oiler. The brush is positioned close to the passing chain so that as the chain passes, the brush can sweep oil over all parts inside the chain. However, this method is very messy, and if the oil splashes inside the can, the oil interferes with proper painting, so the contaminated cans must be discarded.

[0005]

[0005] Electrostatic spray nozzles have been developed, but they have not been effective for spraying oils of higher viscosities. The current trend in the industry indicates that companies are increasingly relying on oils of higher viscosities for lubrication. Higher viscosity oils adhere to mechanical components and serve longer to extend the life of the equipment. This allows for further reduction of oil consumption to address rising production costs. Further, when electrostatic spray nozzles operate with reduced or minimal lubricant flow due to the emission of sharp, thin lines, there can be interruptions or breaks in the lubricant supply, causing harmful arc discharges between the electrodes and the metal parts being sprayed.

[0006]

[0006] To assist in the atomization of such high-viscosity liquids, electrostatic spray nozzle assemblies have utilized the atomization of liquids using compressed air. The problem with such compressed air spray designs is that they lack precision. The air atomization of lubricants combined with static electricity effectively transforms the nozzle system into a spray system closer to an electrostatic paint spray system. The problem with such systems is that the spray is inherently conical and it is difficult to lubricate a relatively small target area without saturating the areas outside the target. As a result, wasted overspray negatively impacts the work environment and makes cleaning difficult. A further drawback of such compressed air spray nozzle designs is that the compressed air and compressed air systems are a significant cost to the user.

Summary of the Invention

[0007] (Summary of the Invention)

[0007] An object of the present invention is to provide an electrostatic spray nozzle assembly and dispensing system that utilize such a spray nozzle assembly that is more effective at accurately and reliably spraying thin 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 characterized as described above that is operable without the need for compressed air assisted atomization when decomposing a liquid into fine line particles.

[0009] A further object is to provide an electrostatic spray system of the foregoing type that is operable to direct an accurate liquid spray pattern onto a small moving target without wasteful overspray that can be harmful to the environment and require costly cleaning.

[0010] Yet another object is to provide an electrostatic lubricant dispensing system of the above type in which the spray nozzle assembly accurately and reliably controls the release of a lubricant so as to direct a very fine line of string or a series of droplets without the possibility of an electrical arc occurring between the charged electrode and the metallic object being coated.

[0011] Still another object is to provide an electrostatic spray nozzle assembly and lubricant dispensing system of the foregoing type that have a relatively simple design and are suitable for economical and reliable use.

[0012] Other objects and advantages of the present invention will become apparent upon reading the following detailed description with reference to the drawings.

Brief Description of the Drawings

[0013] (Brief Description of the Drawings)

Figure 1

[0013] FIG. 1 is a perspective view of a liquid dispensing system having a hydraulic electrostatic spray nozzle assembly according to the present invention for directing a highly viscous liquid, such as oil or other lubricant, onto a sprocket-driven chain without liquid compressed air atomization.

Figure 2

[0014] FIG. 2 is a perspective view of the electrostatic spray nozzle assembly shown in FIG. 1, with the pointed end of the electrode enlarged.

Figure 3

[0015] FIG. 3 is an enlarged longitudinal cross-sectional view of the electrostatic spray nozzle assembly shown.

Figure 4

[0016] It is a side view of the electrostatic spray nozzle assembly shown in FIG. 3.

Figure 5

[0017] It is a downstream end view of the spray nozzle assembly shown in FIG. 4. [Embodiments for Carrying Out the Invention]

[0014]

[0018] Although the present invention is capable of various modifications and alternative configurations, specific exemplary embodiments thereof are shown in the drawings and will be described in detail below. However, it is not intended to limit the present invention to the specific forms disclosed, but rather, the intention is to cover all modifications, alternative structures, and equivalents within the spirit and scope of the present invention.

[0015] (Embodiments for Carrying Out the Invention)

[0019] Referring now more particularly to FIG. 1 of the drawings, there is shown an exemplary liquid distribution system 10 having a hydraulic electrostatic spray nozzle assembly 11 according to the present invention for spraying high-viscosity liquids such as oils and other lubricants for specific directions and applications. For the purposes of this specification, the term "hydraulic spray nozzle assembly" is intended to mean a spray nozzle assembly for spraying and directing a liquid without the accompaniment of compressed air-assisted atomization and liquid direction. The illustrated distribution system 10 is designed to direct a thin string or series of droplets of high-viscosity oil or other lubricant to the pins and roller joints of the sprocket-driven chain 12. Such a chain typically includes longitudinally spaced rollers 14 supported by respective pins 15 and then connected by links 16 on both sides of the rollers 14. In order to prevent wear and chain failure, it is essential to lubricate the joints between the pins 15 and the rollers 14 for proper operation in many applications.

[0016]

[0020] The illustrated hydraulic electrostatic spray nozzle assembly 11 basically comprises 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 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 a vertical leg 24a for fixing to a suitable mounting structure and a horizontal leg 24b having a central opening for supporting the nozzle body 20. The nozzle body 20 in this case includes an upstream portion 28 of relatively small diameter, an intermediate portion 29 of relatively large diameter, and a lower male-threaded cylindrical portion 30 having a diameter somewhat smaller than the intermediate portion 29 and the bracket opening, as shown in FIGS. 2 to 4. The intermediate portion 29 of the nozzle body 20 is supported by the horizontal bracket leg 24b with the lower threaded portion 30 hanging down from the bracket 24 and fixed thereto by a nut 31. A flat portion 34 is formed at the lower protruding end of the end cap 21 in this case to facilitate wrench tightening and removal of the end cap 21. The end cap 21 in this case has an externally threaded upstream hub 35 which is threadedly engaged and fixed to the threaded cavity at the downstream end of the nozzle body, as shown in FIG. 3. It will be understood that the illustrated nozzle body 20 and end cap 21 are separate components, but alternatively they may be integrally formed as a single component.

[0017]

[0021] The electrode 22 has a generally cylindrical configuration having an upstream threaded portion 38 (FIG. 3) fixed in a sealed engagement relationship within the nozzle body 20, a small-diameter downstream cylindrical portion 39 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 on its side a liquid inlet 42 coupled to a liquid supply line 44 communicating with a liquid source such as a source of high-viscosity oil or other lubricant. The liquid inlet 42 communicates with 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 portion 49 (FIGS. 2 and 3) of the end cap 21 around the protruding end 40 of the electrode.

[0018]

[0022] In this case, the electrode 22 has an upstream end that extends above the nozzle body 20 coupled by a right-angle joint 50 to a high-voltage cable 51 connected to a high-voltage source such as a positive power supply (FIG. 1). When the electrode 22 is charged by the high-voltage power supply, it can be seen that the liquid supplied to the inlet 42 becomes charged during its movement along the substantial length of the electrode 22 passing through the nozzle body 20 and the end cap 21. Further, the nozzle body 20 and the end cap 21 are made of an insulating material to enable the charge to be transferred only to the liquid when the liquid is directed through the spray nozzle assembly 20.

[0019]

[0023] In accordance with an important feature of this embodiment, the end cap metering portion 49 around the protruding end of the electrode is defined by a plurality of relatively small metering orifices 49a (FIG. 2) circumferentially spaced within the end cap 21 to accurately control the release of fluid along the protruding end 40 of the electrode 22. In the illustrated embodiment, three circumferentially spaced metering orifices 49a are disposed at the downstream end of the end cap 21 for optimal directioning of the liquid along the protruding end 40 of the electrode 22 without excessive wasteful release or interruption of the liquid flow that could cause a harmful electric arc. The illustrated metering orifices 49a have a semi - moon configuration with a curved side of the orifice 49a extending radially outward of the peripheral wall of the end cap 21 surrounding the electrode 22, as shown in FIG. 2. The metering orifices 49a are designed to allow sufficient liquid to circumscribe the end 40 of the electrode 22, but limit the flow for fine point dispensing and directioning to a specific target area without lack or inconsistency of release. Charging of the liquid has been found to draw the liquid out of the orifice 49a more rapidly than under normal pressure conditions which can cause periodic interruptions in the flow. To control the flow, the metering orifices of the semi - moon configuration are relatively small in size and the total opening area or flow area of the orifices is only about 0.0003 square inches. As shown in the illustrated embodiment, three such metering orifices 49a have been found to provide an optimal flow to completely surround the downstream end 40 of the electrode 22. Alternatively, to achieve good flow conditions, two to six appropriately sized discharge orifices having a total flow area of 0.0002 square inches to 0.0004 square inches can be utilized.

[0020]

[0024] Still further in accordance with this embodiment, the protruding end 40 of the electrode 22 is in the form of a sharp - angled conical tip designed to facilitate the transfer of liquid around the electrode end 40 from the circumferentially spaced metering orifices 49a for directioning in a sharp, thin line or string of droplets. The acute angle of the conical tip 40 (FIG. 2) may be in the range of 10 degrees to 30 degrees, but an angle of about 15 degrees has been found to achieve optimal directioning of the liquid into a thin line less than 0.06 inches wide, depending on the viscosity of the liquid.

[0021]

[0025] During operation, the liquid dispensing system has been found to be operable with respect to such a thin-line target direction of a high-viscosity liquid having a viscosity in the range of 150 cP to 525 cP, including lubricants and oils having a viscosity in the range of 75 cP to 535 cP. 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. The liquid then falls along the electrode 22 and picks up charge (free valence electrons) from the electrode 22. When the liquid picks up the charge, the repulsive force breaks the surface tension of the fluid and can thin the liquid. This also acts to accelerate the liquid as it descends along the surface of the electrode. The highest point of energy transfer occurs at the pointed tip 40 (minimum cross-sectional area) of the electrode 22. The metering orifice 49a of the nozzle cap 21 is sized to have just enough liquid on the pointed tip 40 of the electrode 22 due to the applied high voltage while maintaining a controlled flow onto the tip 40. This also gives additional time for the liquid to become charged. Without such end-cap control of the liquid, the charged liquid could exit the nozzle faster than the fluid entering the nozzle, potentially resulting in a condition where the electrode 22 causes an electrical arc that damages the lack of insulating fluid and between the electrode and the metal chain conveyor.

[0022]

[0026] From the above, it can be seen that a hydraulic electrostatic spray nozzle assembly and a liquid dispensing system are provided that utilize such a spray nozzle assembly that is operable without compressed air atomization to more reliably and effectively direct a pointed thin-line high-viscosity liquid, such as oil or other lubricants, onto a specific target area. This system is operable to direct an accurate liquid spray pattern onto a small moving target without wasteful overspray that can harm the environment and require costly cleaning, and also without the possibility of electrical arc discharge that can damage between the electrostatically charged electrode and the metal object being painted.

Claims

**Claim 1** A liquid dispensing system for dispensing a highly viscous liquid, comprising: a hydraulic electrostatic spray nozzle assembly having a nozzle body; an elongated electrode supported within the nozzle body for connection to a power source and having a distal end projecting downstream from the nozzle body; a source of highly viscous liquid having a viscosity of 75 cP to 535 cP; wherein the nozzle body and the elongated electrode define an annular liquid flow path around the electrode that communicates with the projecting distal end downstream of the electrode; the nozzle body has a liquid inlet coupled to the source of highly viscous liquid for guiding the highly viscous liquid through the annular liquid flow path between the electrode and the nozzle body to electrostatically charge the highly viscous liquid; the nozzle body has a downstream end defining a plurality of circumferentially spaced circumferential metering orifices around the electrode for controlling the discharge of the electrostatically charged liquid at the projecting distal end of the electrode for guiding in a thin line from the electrode; a liquid dispensing system. **Claim 2** The liquid dispensing system according to claim 1, wherein the circumferentially spaced metering orifices control the discharge of the highly viscous electrostatically charged liquid at the distal end of the electrode for discharge in a continuous thin line. **Claim 3** The liquid dispensing system according to claim 2, wherein the plurality of circumferentially spaced metering orifices control the discharge of the electrostatically charged liquid in a thin line having a width of 0.06 inches or less. **Claim 4** The liquid dispensing system according to claim 1, wherein the source of highly viscous liquid is a source of lubricant. **Claim 5** The liquid dispensing system according to claim 1, wherein the source of highly viscous liquid is a source of oil. **Claim 6** The liquid dispensing system according to claim 1, wherein the highly viscous liquid is guided through the annular liquid flow path and discharged from the spray nozzle assembly without compressed air atomization. **Claim 7** The liquid dispensing system according to claim 1, wherein the nozzle body includes a downstream end cap, and the circumferential metering orifices are formed in the end cap. **Claim 8** The liquid dispensing system according to claim 1, wherein the nozzle body and the downstream end cap are made of an electrically insulating material. **Claim 9** The liquid dispensing system according to claim 1, wherein the metering orifices extend outside the electrode in a semi-circular configuration. **Claim 10** The liquid distribution system according to claim 1, wherein the metering orifice defines a total liquid flow area of 0.0002 square inches to 0.0004 square inches on the protruding end of the electrode.

11. The liquid distribution system according to claim 1, wherein the protruding end of the electrode is in the form of a conical tip so as to transfer liquid inward along the end of the electrode from the circumferentially spaced metering orifices for the release of the highly viscous liquid in the thin line.

12. The liquid distribution system according to claim 1, wherein the conical tip of the electrode tapers inward in the downstream direction at an angle of 10 degrees to 30 degrees.

13. A lubricant distribution system for distribution, a hydraulic electrostatic spray nozzle assembly having a nozzle body, an elongated electrode supported within the nozzle body for coupling to a power source, protruding outward from the nozzle body, and having a downstream end configured in a conical shape that tapers inward in the downstream direction, and an oil supply source, wherein the nozzle body and the elongated electrode define an annular liquid flow path around the electrode that communicates with the downstream end of the electrode, the nozzle body having a liquid inlet coupled to the liquid supply source of the oil, for guiding the oil through the annular liquid flow path between the electrode and the nozzle body to electrostatically charge the oil, the nozzle body having a downstream end that defines a plurality of circumferentially spaced circumferential metering orifices around the electrode for controlling the release of the electrostatically charged oil to the protruding end at the electrode for guiding in a thin line from the electrode, a lubricant distribution system.

14. The lubricant distribution system according to claim 13, wherein the plurality of circumferentially spaced metering orifices control the release of the electrostatically charged oil in a thin line having a width of 0.06 inches or less.

15. The lubricant distribution system according to claim 13, wherein the oil supply source has a viscosity of 75 cP to 535 cP.

16. The lubricant distribution system according to claim 13, wherein the oil is guided through the annular liquid flow path and discharged from the spray nozzle assembly without compressed air atomization.

17. The lubricant distribution system according to claim 13, wherein the nozzle body includes a downstream end cap, and the circumferential metering orifices are formed in the end cap.

18. The lubricant distribution system according to claim 13, wherein the metering orifice defines a total oil flow area of from 0.0002 square inches to 0.0004 square inches on the protruding end of the electrode. **Claim 19** The lubricant distribution system according to claim 13, wherein the conical tip of the electrode tapers inwardly in the downstream direction at an angle of from 10 degrees to 30 degrees.

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