CA1162041A - Electrostatic spray coating apparatus - Google Patents
Electrostatic spray coating apparatusInfo
- Publication number
- CA1162041A CA1162041A CA000345425A CA345425A CA1162041A CA 1162041 A CA1162041 A CA 1162041A CA 000345425 A CA000345425 A CA 000345425A CA 345425 A CA345425 A CA 345425A CA 1162041 A CA1162041 A CA 1162041A
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- voltage
- converting
- air
- set forth
- electrostatic spray
- Prior art date
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Abstract
ELECTROSTATIC SPRAY COATING APPARATUS
ABSTRACT OF THE DISCLOSURE
An electrostatic spray gun apparatus having an entirely self-contained lighweight electrical power supply adapted to convert the kinetic energy available in a moving air stream into the required high DC potential and which dispenses with external electrical supply connections thereto.
ABSTRACT OF THE DISCLOSURE
An electrostatic spray gun apparatus having an entirely self-contained lighweight electrical power supply adapted to convert the kinetic energy available in a moving air stream into the required high DC potential and which dispenses with external electrical supply connections thereto.
Description
ELECTROSTATIC SPRAY COATING A _ARATUS
This invention relates to electrostratic spray coat-ing systems wherein the deposition of coating materials upon a workpiece is enhanced through the application of electro-static forces and, more particularly, to an improved spray gun apparatus incorporating an entirely self-contained elec-trical power supply.
Electrostatic spray coating systems of both the air-atomized and airless types are widely utilized in paint spraying and for deposition of other coating materials.
Spray gun apparatus conventionally employed therein is gener-ally constituted by an insulating barrel member having a grounded handle or mount disposed at one end thereof and a selectively sized and shaped high voltage electrode extending from the other end thereof disposed adjacent to the locus of atomization. Such electrode is usually charged to a poten-~;tial in the neighborhood of from 30 to 85 kilovolts, and incertain installations as high as 150 kilovolts, to create a corona discharge condition and a concomitant electric field of appreciable magnitude. Under such conditions, the corona dl~scharge current flowing from the high voltage eléctrode creates a region adjacent to the locus of atomization rich in unlpolar ions that attach themselves to and charge the paint or other coating material sp~ray droplets. Alternatively, for conductive coating materials ~ontact charging of the spray ~droplets will occur in the high field strength region around the fluid orifice. The charged droplets are then displaced, under the conjoint influence of their own inertial forces and the~ electrostatic field extant in the spray region, toward a grounded workpiece. In accord with conventional practice, maximum paint savings are g~nerally effected by maintaining :
~ 1~204 ~
the charging voltage as high as possible and of such magni-tude as to produce an average depositing field strength of at least 5,000 volts/inch, and preferably as high as 10,000 volts/inch, between the spray gun and the workpiece. As a concomitant thereto, the spray velocity in the vicinity of the workpiece should be of minimal magnitude consistent with the demands of adequate atomization and paint flow.
The requisite charging voltages are conventionally obtained either through the utilization of externally located standard electronic high voltage power supplies or by the incorporation of an electrogasdynamic high voltage generator within the spray gun body. The standard electronic high voltage power supplies are relatively large, heavy and expen-sive and are so constituted as to inherently function with essentially "constant voltage" type characteristics. In addition thereto and because of the magnitude of the poten-tials involved, the high voltage cable interconnecting such power supply with the spray gun is heavy, bulky and relative-ly inflexible, adding undesired weight to the gun assembly which, because of the concomitant high voltage insulation requirements is rendered unduly large, complex, and, in most instances, not field serviceable.
While the electrogasdynamic powered spray coating apparatus is possessed of several advantageous features as compared to the standard high voltage power supplies, such conventionally require external generation of the relatively low, but still multi-kilovolt, excitation potentials for the spray apparatus-contained electrogasdynamic generator and as such, require utilization of an external power supply con-nected to the spray head as well as requiring the use of pre-conditioned or ~Iseeded~l air for reliable operation thereof.
~, l 16~4 ~
The avoidance of dependence upon a "seededt' air sup-ply and the minimization, if not elimination, of all external power supplies and associated electrical connections to the electrostatic spray apparatus has been a long-sought ob~ec-tive in this field. However, the antithetical requirements of required high operating potentials with attendant current limiting or constant current characteristics, the required utilization of conventionally available compressed air sup-plies, and the avoidance of deleterious discharge potentials, all within the framework of lightweight, small size and ex-tended trouble-free operation over long periods of time, have effectively precluded, despite various suggested solutions, practical realization of this objective.
This invention may be briefly described as an im-proved construction for a lightweight electrostatic spray coating apparatus incorporating an entirely self-contained electrical power supply and which includes, in its broadest aspects, means for converting the energy of a fluid under pressure into electrical energy suitable for use as a power source for the spray apparatus and/or appropriate for appli-cation to the spray apparatus charging electrode. In its broadest aspects, the present invention also contemplates means for converting the kinetic energy of a moving air stream into kinetic energy of a rotating solid and means for converting the latter into electrical energy suitable for use as a power source for the spray apparatus and/or appropriate for application to the spray apparatus charging electrode.
Pursuant thereto, the invention broadly includes an air driven low voltage alternator, a rectifier and voltage regu lator for converting the alternator output into a substanti-~ally constant DC voltage input Eor a high frequency oscillat-or and a multi-stage voltage multiplier for further increas-ing the magni~ude of the transformed output voltage of the high frequency oscillator and converting the same to the , i 162~ l 30-100 kilovolt potential level conventionally required to effect the electrostatically enhanced deposition of coating materials. Further, in its broad aspects, the subject inven-tion also includes an energy conversion unit for electrostat-ic spray coating apparatus comprising a selectively sized and arranged lightweight high speed impulse type air motor di-rectly driving a compatible magnetic armature low voltage alternator adapted to provide an effectively instantaneous voltage output in response to demand for power.
In its narrower aspects, the subject invention in-cludes the provision of a spray head incorporating a light-weight~ self-contained power supply made up of a high speed, impulse-type low-inertia air motor directly driving a magnet-ic armature low voltage alternator, a solid state rectifier and voltage regulator for converting the alternator output into a substantially constant DC voltage input for a high frequency oscillator adapted to provide a stepped up or transformed essentially square or sine wave output of about
This invention relates to electrostratic spray coat-ing systems wherein the deposition of coating materials upon a workpiece is enhanced through the application of electro-static forces and, more particularly, to an improved spray gun apparatus incorporating an entirely self-contained elec-trical power supply.
Electrostatic spray coating systems of both the air-atomized and airless types are widely utilized in paint spraying and for deposition of other coating materials.
Spray gun apparatus conventionally employed therein is gener-ally constituted by an insulating barrel member having a grounded handle or mount disposed at one end thereof and a selectively sized and shaped high voltage electrode extending from the other end thereof disposed adjacent to the locus of atomization. Such electrode is usually charged to a poten-~;tial in the neighborhood of from 30 to 85 kilovolts, and incertain installations as high as 150 kilovolts, to create a corona discharge condition and a concomitant electric field of appreciable magnitude. Under such conditions, the corona dl~scharge current flowing from the high voltage eléctrode creates a region adjacent to the locus of atomization rich in unlpolar ions that attach themselves to and charge the paint or other coating material sp~ray droplets. Alternatively, for conductive coating materials ~ontact charging of the spray ~droplets will occur in the high field strength region around the fluid orifice. The charged droplets are then displaced, under the conjoint influence of their own inertial forces and the~ electrostatic field extant in the spray region, toward a grounded workpiece. In accord with conventional practice, maximum paint savings are g~nerally effected by maintaining :
~ 1~204 ~
the charging voltage as high as possible and of such magni-tude as to produce an average depositing field strength of at least 5,000 volts/inch, and preferably as high as 10,000 volts/inch, between the spray gun and the workpiece. As a concomitant thereto, the spray velocity in the vicinity of the workpiece should be of minimal magnitude consistent with the demands of adequate atomization and paint flow.
The requisite charging voltages are conventionally obtained either through the utilization of externally located standard electronic high voltage power supplies or by the incorporation of an electrogasdynamic high voltage generator within the spray gun body. The standard electronic high voltage power supplies are relatively large, heavy and expen-sive and are so constituted as to inherently function with essentially "constant voltage" type characteristics. In addition thereto and because of the magnitude of the poten-tials involved, the high voltage cable interconnecting such power supply with the spray gun is heavy, bulky and relative-ly inflexible, adding undesired weight to the gun assembly which, because of the concomitant high voltage insulation requirements is rendered unduly large, complex, and, in most instances, not field serviceable.
While the electrogasdynamic powered spray coating apparatus is possessed of several advantageous features as compared to the standard high voltage power supplies, such conventionally require external generation of the relatively low, but still multi-kilovolt, excitation potentials for the spray apparatus-contained electrogasdynamic generator and as such, require utilization of an external power supply con-nected to the spray head as well as requiring the use of pre-conditioned or ~Iseeded~l air for reliable operation thereof.
~, l 16~4 ~
The avoidance of dependence upon a "seededt' air sup-ply and the minimization, if not elimination, of all external power supplies and associated electrical connections to the electrostatic spray apparatus has been a long-sought ob~ec-tive in this field. However, the antithetical requirements of required high operating potentials with attendant current limiting or constant current characteristics, the required utilization of conventionally available compressed air sup-plies, and the avoidance of deleterious discharge potentials, all within the framework of lightweight, small size and ex-tended trouble-free operation over long periods of time, have effectively precluded, despite various suggested solutions, practical realization of this objective.
This invention may be briefly described as an im-proved construction for a lightweight electrostatic spray coating apparatus incorporating an entirely self-contained electrical power supply and which includes, in its broadest aspects, means for converting the energy of a fluid under pressure into electrical energy suitable for use as a power source for the spray apparatus and/or appropriate for appli-cation to the spray apparatus charging electrode. In its broadest aspects, the present invention also contemplates means for converting the kinetic energy of a moving air stream into kinetic energy of a rotating solid and means for converting the latter into electrical energy suitable for use as a power source for the spray apparatus and/or appropriate for application to the spray apparatus charging electrode.
Pursuant thereto, the invention broadly includes an air driven low voltage alternator, a rectifier and voltage regu lator for converting the alternator output into a substanti-~ally constant DC voltage input Eor a high frequency oscillat-or and a multi-stage voltage multiplier for further increas-ing the magni~ude of the transformed output voltage of the high frequency oscillator and converting the same to the , i 162~ l 30-100 kilovolt potential level conventionally required to effect the electrostatically enhanced deposition of coating materials. Further, in its broad aspects, the subject inven-tion also includes an energy conversion unit for electrostat-ic spray coating apparatus comprising a selectively sized and arranged lightweight high speed impulse type air motor di-rectly driving a compatible magnetic armature low voltage alternator adapted to provide an effectively instantaneous voltage output in response to demand for power.
In its narrower aspects, the subject invention in-cludes the provision of a spray head incorporating a light-weight~ self-contained power supply made up of a high speed, impulse-type low-inertia air motor directly driving a magnet-ic armature low voltage alternator, a solid state rectifier and voltage regulator for converting the alternator output into a substantially constant DC voltage input for a high frequency oscillator adapted to provide a stepped up or transformed essentially square or sine wave output of about
2.5 kilovolts peak and a solid state multi-stage voltage mul-tiplier employing standard 5 kilovolt components for increas-ing the magnitude of the transformed output voltage of the high frequency oscillator to the 30 to 100 kilovolt level required to effect the electrostatically enhanced deposition of coating materials.
In a still narrower aspect, the subject invention includes the selective combination of diminutive and light-weight components operative within a framework of mechanical and electrical opera-ting parameters that provide an operative lightweight electrostatic spray gun unit adapted to utilize conventional plant compressed air supply as the prime movant and to deliver conventionally required output voltages for paint spraying and the like at acceptably low current levels.
Among the advantages of the subject invention is the provision of a lightweight diminutively sized and readily 1 16~
manipulatable electrostatic spray gun that dispenses with all external electrical connections thereto and the provision of a self-contained electrical power generating system for elec-trostatic spray coating apparatus that derives its electric power solely throu~h direct conversion of the kinetic energy of a moving air stream. Other advantages of the subject in-vention include the provision of a self-contained high volt-age power supply for electrostatic paint spray guns that is drivable from conventionally available compressed air sources and employs readily available electrical components; the pro-vision of a diminutive high voltage power supply of enduring and reliable character adapted to produce output voltages of 30-100 kilovolts at a current level in the order of 50 micro-amperes; and the provision of a reliable high voltage power supply adapted to be contained within a hand-holdable spray coating apparatus without materially increasing the weight thereof. Still further advantages of the subject invention include the provision of electrostatic spray coating appa-ratus that is completely free of any external electrical power connections and requires only an available conventional source of compressed air for operability. Yet another advan-tage of the subject invention is the provision of a cartridge-type multi-element power supply made up of essenti-ally monolithic subassemblies that are assemblable and are individually replaceable for easy field servicing thereof.
In more particularity, the practice of the herein-disclosed invention provides an electrostatic spray gun assembly having an entirely self-contained electrical power supply that is devoid of e~ternal electrical connection thereto and which is characterized by conventional opera-tional parameters of a re~uired 30-100 kilovolt output at approximately 50 microamps; a power level of approximately 3 watts; a total weight of between about 1-1/2 to 3 pounds and the utilization of conventionally available compressed air supply of between about 20 to 80 psig at flow rates no great-er than 5 scfm.
The primary objective of this invention is the pro-vision of improved electrostatic spray coating apparatus in-corporating an entirely self-contained electrical power supply.
Among the further objects of the invention is the provision of an improved power supply construction for elec-trostatic spray coating operations of such diminutive size as to be disposed within the spray head apparatus and drivable by compressed air.
Still another object of this invention is the pro-vision of a self-contained and improved cartridge-type power supply for electrostatic spray coating devices that is readi-ly field replaceable.
Other objects and advantages of the subject inven-tion will be apparent from the following portions of this specification and claims and from the appended drawings which illustrate a presently preferred construction incorporating the principles of this invention.
Referring to the drawings:
FIG. 1 is a schematic side elevational view, partly in section, showing the disposition of the elements of the power supply disposed within a hand manipulatable spray gun of the air atomizing type;
FIG. lA is a schematic flow diagram indicative of the nature of flow of the gaseous prime movant in the dis-closed system;
FIG. 2 is a schematic vertical section of a suitable air motor configuration;
FIG. 3 is a schematic sectional view of a suitable air motor-alternator subassembly construction;
FIG. 4 is a schematic representation of the typical performance characteristics of the air motor;
~- 1 16~0~ ~
FIG. 5 is a schematic circuit diagram of a rectifier-voltage regulator ircuit;
FIG. 6 is a schematic circuit diagram of an oscillator-transformer circuit;
FIG. 7 is a schematic circuit diagram of a suitable long chain series voltage multiplier;
FIG. 8 is a schematic vertical section of an air pressure regulator device; and FIG~ 9 (on the s~eet of FI~. lA~ is a schematic vertical section of another embod~ment of a pressure regulator device.
Referring to FIG. 1, there are generally and sche-matically illustrated the components of a hand manipulatable type of electrostatic spray gun 10 for paint spraying and the like embodying the principles of this invention. The spray gun 10 includes a generally cylindrical and elongate barrel portion 12 formed of insulating material and a pistol grip type handle 14 formed of conducting material and whose upper portion encircles the rear end of the barrel portion 12. An air hose 16 connectable to a remote source of compressed air (not shown), suitably a conventional compressed plant air supply capable of supplying air at a pressure range of from 20 to 80 or more psig and at a flow rate of at least about 3 scfm, and more preferably at least 10 scfm, is connected to the base of the handle 1~ through a suitable fitting 18.
: As shown in FIG. 1, the spray gun 10 constructed in accordance with the principles of this invention differs from those conventionally employed in both air-atomized and air-less electrostatic spray coating systems in that it has con-nected thereto only a~paint supply line 38, an air supply line 16 and a ground connection and is totally devoid of :external electrical power supply connections theretor The subject construction thus completely dispenses with the here-tofore required large and heavy floor-supported electronic 0~
power supply units and the associated heavy and relatively inflexible insulated cables required to transmit the exter-nally generated charging potentials to the gun, as well as also dispensing with the seeded air supply and the insulated electrical cable conventionally required to transmit the excitation potentials to electrogasdynamically powered spray gun assemblies.
Disposed within the handle 14 is an air flow conduit 20 connected to a flow control valve 22 operable through dis-placement of a trigger 24 by the user of the gun. The output side of the flow control valve 22 is connected to a conduit 26 which fluidly connects with a control valve and regulator assembly 27 schematically shown in FIG. 1. Exiting from the assembly 27 is a primary air flow conduit 30 and an auxiliary air flow conduit 28. The primary air flow conduit 30 serves (in an air-atomized gun of the type described) to convey a flow of compressed air to an air cap assembly 32 wherein, as indicated by the further subdivided air flow conduits 34 and 36, such air may be used for conventional air-induced atomi-zation of the coating material introduced from a remote sup-ply through the hose 38 and fitting 40 and conveyed to the air cap assembly 32 via conduit 42 and/or may be employed as "fan" air for shaping the emitted spray of the atomized coat-ing material.
: : ~ The structure and configuration of the air cap assembly 32 and the internal design of the air and coating material conduits therewithin may be essentially conventional in nature and U.S. Patents 3,645,447: 3,693,877; and
In a still narrower aspect, the subject invention includes the selective combination of diminutive and light-weight components operative within a framework of mechanical and electrical opera-ting parameters that provide an operative lightweight electrostatic spray gun unit adapted to utilize conventional plant compressed air supply as the prime movant and to deliver conventionally required output voltages for paint spraying and the like at acceptably low current levels.
Among the advantages of the subject invention is the provision of a lightweight diminutively sized and readily 1 16~
manipulatable electrostatic spray gun that dispenses with all external electrical connections thereto and the provision of a self-contained electrical power generating system for elec-trostatic spray coating apparatus that derives its electric power solely throu~h direct conversion of the kinetic energy of a moving air stream. Other advantages of the subject in-vention include the provision of a self-contained high volt-age power supply for electrostatic paint spray guns that is drivable from conventionally available compressed air sources and employs readily available electrical components; the pro-vision of a diminutive high voltage power supply of enduring and reliable character adapted to produce output voltages of 30-100 kilovolts at a current level in the order of 50 micro-amperes; and the provision of a reliable high voltage power supply adapted to be contained within a hand-holdable spray coating apparatus without materially increasing the weight thereof. Still further advantages of the subject invention include the provision of electrostatic spray coating appa-ratus that is completely free of any external electrical power connections and requires only an available conventional source of compressed air for operability. Yet another advan-tage of the subject invention is the provision of a cartridge-type multi-element power supply made up of essenti-ally monolithic subassemblies that are assemblable and are individually replaceable for easy field servicing thereof.
In more particularity, the practice of the herein-disclosed invention provides an electrostatic spray gun assembly having an entirely self-contained electrical power supply that is devoid of e~ternal electrical connection thereto and which is characterized by conventional opera-tional parameters of a re~uired 30-100 kilovolt output at approximately 50 microamps; a power level of approximately 3 watts; a total weight of between about 1-1/2 to 3 pounds and the utilization of conventionally available compressed air supply of between about 20 to 80 psig at flow rates no great-er than 5 scfm.
The primary objective of this invention is the pro-vision of improved electrostatic spray coating apparatus in-corporating an entirely self-contained electrical power supply.
Among the further objects of the invention is the provision of an improved power supply construction for elec-trostatic spray coating operations of such diminutive size as to be disposed within the spray head apparatus and drivable by compressed air.
Still another object of this invention is the pro-vision of a self-contained and improved cartridge-type power supply for electrostatic spray coating devices that is readi-ly field replaceable.
Other objects and advantages of the subject inven-tion will be apparent from the following portions of this specification and claims and from the appended drawings which illustrate a presently preferred construction incorporating the principles of this invention.
Referring to the drawings:
FIG. 1 is a schematic side elevational view, partly in section, showing the disposition of the elements of the power supply disposed within a hand manipulatable spray gun of the air atomizing type;
FIG. lA is a schematic flow diagram indicative of the nature of flow of the gaseous prime movant in the dis-closed system;
FIG. 2 is a schematic vertical section of a suitable air motor configuration;
FIG. 3 is a schematic sectional view of a suitable air motor-alternator subassembly construction;
FIG. 4 is a schematic representation of the typical performance characteristics of the air motor;
~- 1 16~0~ ~
FIG. 5 is a schematic circuit diagram of a rectifier-voltage regulator ircuit;
FIG. 6 is a schematic circuit diagram of an oscillator-transformer circuit;
FIG. 7 is a schematic circuit diagram of a suitable long chain series voltage multiplier;
FIG. 8 is a schematic vertical section of an air pressure regulator device; and FIG~ 9 (on the s~eet of FI~. lA~ is a schematic vertical section of another embod~ment of a pressure regulator device.
Referring to FIG. 1, there are generally and sche-matically illustrated the components of a hand manipulatable type of electrostatic spray gun 10 for paint spraying and the like embodying the principles of this invention. The spray gun 10 includes a generally cylindrical and elongate barrel portion 12 formed of insulating material and a pistol grip type handle 14 formed of conducting material and whose upper portion encircles the rear end of the barrel portion 12. An air hose 16 connectable to a remote source of compressed air (not shown), suitably a conventional compressed plant air supply capable of supplying air at a pressure range of from 20 to 80 or more psig and at a flow rate of at least about 3 scfm, and more preferably at least 10 scfm, is connected to the base of the handle 1~ through a suitable fitting 18.
: As shown in FIG. 1, the spray gun 10 constructed in accordance with the principles of this invention differs from those conventionally employed in both air-atomized and air-less electrostatic spray coating systems in that it has con-nected thereto only a~paint supply line 38, an air supply line 16 and a ground connection and is totally devoid of :external electrical power supply connections theretor The subject construction thus completely dispenses with the here-tofore required large and heavy floor-supported electronic 0~
power supply units and the associated heavy and relatively inflexible insulated cables required to transmit the exter-nally generated charging potentials to the gun, as well as also dispensing with the seeded air supply and the insulated electrical cable conventionally required to transmit the excitation potentials to electrogasdynamically powered spray gun assemblies.
Disposed within the handle 14 is an air flow conduit 20 connected to a flow control valve 22 operable through dis-placement of a trigger 24 by the user of the gun. The output side of the flow control valve 22 is connected to a conduit 26 which fluidly connects with a control valve and regulator assembly 27 schematically shown in FIG. 1. Exiting from the assembly 27 is a primary air flow conduit 30 and an auxiliary air flow conduit 28. The primary air flow conduit 30 serves (in an air-atomized gun of the type described) to convey a flow of compressed air to an air cap assembly 32 wherein, as indicated by the further subdivided air flow conduits 34 and 36, such air may be used for conventional air-induced atomi-zation of the coating material introduced from a remote sup-ply through the hose 38 and fitting 40 and conveyed to the air cap assembly 32 via conduit 42 and/or may be employed as "fan" air for shaping the emitted spray of the atomized coat-ing material.
: : ~ The structure and configuration of the air cap assembly 32 and the internal design of the air and coating material conduits therewithin may be essentially conventional in nature and U.S. Patents 3,645,447: 3,693,877; and
3,843,052 are exemplary of suitable constructions therefor.
The electrode system incorporated in the air cap 32 may also be con~entional, as is the grounding of the conductive handle portion 14, by means of a conductive sheath 44 disposed around the air hose 16 or by means of a suitable ground lead associated there~ith.
, 1:l62043 Disposed within the barrel portion 12 and the upper section o~ the handle portion 14 of the gun 10 is an elongate removable power supply cartridge member ~5. The cartridge member 45 contains the hereinafter-described operative com-ponents of the power supply and is of generally cylindrical configuration having a rear section 46 of appreciably greater diameter than its forward section 48.
When the cartridge 45 is properly seated within its complementarily contoured receiving bore within the gun bar-rel 12, the auxiliary air flow conduit 28 is directly con-nected to an input nozzle 50 of a diminutive air motor assembly 52 to rotatably drive the rotor 56 thereof at high speed. The air flow through the air motor 52 may suitably be vented to the atmosphere through an exhaust channel 54 at the rear of the gun barrel 12. The rotor 56 of the air motor 52 is mounted on a common shaft 58 with the armature 60 of an adjacent alternator 62 to form an effectively integral low inertia assembly capable of rapid acceleration to high speeds with a concomitant long life. The armature 60 is disposed within a cylindrical epoxy-coated sleeve type stator 64, preferably of tape wound construction. The air motor 52 and the alternator 62 comprise an essentially integral sub-assembly that is both of small size, lightweight and low ~inertia. The described direct coupling of the air motor 52 with the alternator 62 operates to effect a direct conversion of kinetic energy available in the moving air stream in con-dui~t 28 into electrical energy in the nature of an alternat-ing voltage suitably of about 8-20 volts r.m.s. at a frequen-cy sf about 250 to 350 cycles/sec.
The alternating voltage output of the alternator 62 is introduced, through leads 68, into a rectifier 70 and voltage regulator 72 wherein it is converted into a substan-tially constant DC voltage, suitably of about 8 to 20 volts in magnitude. The regulated output voltage of rectifier 72 .:
' :
2~ ~
drives a high frequency oscillator 74 to produce a low volt-age sine or square wave output suitably at a frequency in the range of from 10 to 50 kilohertz. The high frequency but low voltage output of the oscillator 74 is then raised by a transformer 76 which comprises an integral part of the oscil-lator circuit, to provide a + 2,500 volt square or sine wave output at the specified frequency range.
The high frequency, high voltage output of the transformer 76 is introduced into a long chain multiplier 80, suitably a series multiplier of about 20 or more stages, to elevate the input voltage into a desired 30 to 100 kilovolt rectified output voltage which is fed to the electrode assembly in the air cap 32 via lead 84 and a limiting resist-ance 82. A major part of limiting resistance 82 may alter-natively be placed between the low voltage end of cartridge 45 and the grounded handle 14.
The critical size and weight limitations herein attendant for electrostatic spray coating apparatus, and par-ticularly for hand manipulatable spray guns, can be effec-tively satisfied by utilization of a prime movant air supply and flow system of the type schematically illustrated in FIG.
lA. As there shown, the prime movant source comprises a con-ventional plant compressed air supply 85 that normally sup-plies clean air at pressures greater than 70 ps.ig and at available flow rates in excess of 15 scfm. Such compressed air is initially introduced into an externally located, con-ventional and commercially available pressure regulator 86 adapted to provide a fixed and regulated supply of compressed air at 70 psig. A suitable regulator may, for exa~ple, be Binks No. 85-201 as manufactured and sold by Binks Manufac-turing Company of Franklin Park, Illinois. Such regulated air at 70 psig is introduced via the air hose 16 to the gun 10. Previous limitations on the effective length of air hose for electrostatic spray apparatus, which was about 25 feet, ~ ~2~ 1 are now effectively removed and any length of air hose can now be employed. Air flow within the gun is primarily con-trolled by actuation of the trigger 24 and shift of the flow control valve 22 disposed within conduit 20 in the handle 14 from fully closed to fully opened condition. Downstream of trigger 24 the primary air flow within conduit 26 is intro-duced into the control valve and regulator assembly 27. Such control valve and regulator assembly 27 is operative to selectively and independently regulate the flow of air via conduit 30 to the air cap for both atomization of the coating fluid and fan width control, while also effecting a selective control of the flow of air at substantially fixed pressure to conduit 28 to the energy conversion unit.
As mentioned earlier, spray guns of the type herein of concern employable in commercial electrostatic paint spraying or other coating operations must satisfy and fall within a practical and established framework of mechanical and electrical parameters. In general, hand-holdable electrostatic spray guns desirably should weigh less than three pounds, should provide an operating potential of from 30 to 100 kilovolts at a current level of about 50 micro-amperes, and should be operable with conventional plant supply of compressed air at pressures from about 20 to 80 psig. In addition, such guns must include means for limiting the current flow to prevent deleterious arc-type discharge when the high voltage electrode approaches a grounded object.
The following portions of this specification will describe, in more detail, a presently preferred embodiment of a self-contained electrical power supply for electrostatic spray guns that (a) weighs about 1/2 pound, (b) is operable from conventionally available compressed air supplies of from 20 to 80 psig at a flow rate no greater than 5 scfm, (c) pro-vides a 50 kilovolt minimum output at 50 microamperes with a maximum current flow of about 200 microamperes at short 1 1~20~ ~
circuit, and (d) is conveniently formed as a replaceable cartridge to facilitate field servicing of the spray equipment--all of which permit ready cartridge-type incorpo-ration within hand-holdable spray guns and concomi~ant satis-faction of the currently accepted and recognized mechanical and electrical parameters therefor.
Further, there is also described a presently pre-ferred embodiment of a lightweight energy conversion assembly for electrostatic spray guns that (a) is operable from con-ventionally available compressed air supplies of about 70 psig at flow rates of about 3 scfm, (b) provides an 8-20 volt alternating output at 5-10 watts/ (c) provides desired output voltage to satisfy electrostatically enhanced deposition of spray coating material, and (d) is conveniently formed as a separable component of a replaceable cartridge assembly to facilitate field servicing of the spray equipment.
The air motor 52, alternator 62, rectifier 70 and voltage regulator 72 subassembly preferably is desirably con-structed to provide exemplary operating characteristics such as (a) relatively constant output voltage of 5-10 volts DC at a power level of 5-10 watts from a 20-80 psig oil-free air supply utilizing less than 5 scfm of compressed air exhaust-ing at atmosphere pressure, (b) acceleration of the air motor rotor 56 and armature 60 to 80% of full speed within a maxi-mum of about 0.2 second from trigger actuation, and (c) a light weight, in the order of 3 ounces, with a concomitant structural durability to provide for long operating life.
As best shown in FIGS. 2 and 3, a presently pre-ferred construction for the air motor 52 comprises a simple impulse type air motor wherein the rotor 56, when exposed to an entering air stream through nozzle 50 moving at about 300 meters/sec., has a theoretical maximum speed of about 300,000 r.p.m. so as to conveniently and readily permit operation at speeds in the order of 10,000 to 30,000 r.p.m. while provid-ing the necessary torque to drive the alternator 62 in such ~ I~62~41 manner as to provide the desired power output from the avail-able kinetic energy in the moving air stream.
Compressed air flowing at about 4 scfm at a pressure of 40 psig has a theoretical power capability of about 200 watts, and at flow conditions of about 3 scfm at a pressure of 70 psig, it has a theoretical power capability of about 250 watts. Since the desired output of the alternator 62 and the rectifier 70 are in the order of about 10 watts or less, the described system renders the full pressure drop available to drive the air motor 52 and associated alternator 62.
~dditionally, the above described preferred impulse turbine type of air motor avoids the utilization of sliding seals and permits the use of ball bearings, oil-impregnated bushings or other suitable bearing elements, suitably of the type em-ployed in dentists' drills and the like for long-lived high speed operation.
In order to obtain the desired rapid acceleration of the~armature 60 of the alternator 62, the inertia of the air motor rotor 56 and armature 60 must be kept as small as pos-sible.
To the above ends, the rotor 56 of the air motor 52 is about 2~5 cm. in diameter, about 0.6 cm. thick and is con-veniently of lightweight, high strength resin such as "Delrin"
(a trademark), manufactured by E.~I. DuPont de Nemours & Co., Inc. The rotor 56 is mounted adjacent one end of shaft 58 which is terminally supported in sealed ball bearings 59.
The ball bearing-mounted rotor 56 is disposed in close peripheral clearance within a chamber 61 formed in a shell ~houslng 63. The prime movant air from conduit 28 is intro-duce~d through a selectively located and sized orifice 50 that is e~ssentially tangentially oriented relative to the rotor periphery and is about 0.15 cm. in diameter. The diameter of the aperture 50 is selected to provide air exiting into cham-ber 61 in the vicinity of sonic velocity and to limit flow to 0~1 approximately 3 scfm. After impingement on the blade sur-faces of rotor 56, such air is vented from chamber 61 through one or preferably a number of ports 54. Disposed downstream of the ports 54 is a muffler plate 67 disposed in peripheral engagement with an o-ring 69, for venting such exiting air to the atmosphere from the rear of the gun with minimal noise.
A suitable muffler 67 comprises a sintered ceramic or metal disc of about 0.3 cm. thickness.
As shown in FIG~ 4, the torque speed characteristic of the described impulse type turbine, shows that output torque is essentially inversely proportional to speed of rotation. As such, desirable torque levels are achieved at speeds of less than 30,000 r.p.m. as represented by the shaded portion under the curve. Such torque-speed limitation poses a further operating parameter upon the design of the alternator 62.
The alternator unit functions to convert the rota-tional kinetic energy of the air motor rotor 56 into electri-cal energy, which in turn serves as the electrical power source for the high voltage for the electrostatically en-hanced deposition o~ the spray coating material. As previ-ously described, such alternator unit should provide a power output of from 5 to 10 watts at an output voltage of at least 5, and preferably greater than 10 volts, and should do so with low losses and internal dissipation and in a highly reliable manner through avoidance of any brushes, wipers or other commutating means. The above ob]ectives must be satis-fied in an assembly that is both small in size and weight and is possessed of minimal inertia.
To the above ends, the alternator 62 is disposed immediately adjacent to the rotor 56 and within the common housing 63. The armature 60 is mounted on shaft 58 and is directly driven by rotor 56. Such armature 60 preferably comprises a high energy permanent magnet 100 about 5/8 inch 204 ~ `~
long and about 1/2 inch in diameter, magnetized across a diameter thereof. Present knowledge indicates that magnet diameters in excess of 1/2 inch are attended by unaccep~able inert~a charactexistics. Alinc~ 8 Ca tradem~xk~ is a preferred material for such magnet armature although ~t~er mater~als including Aln~co 5 (a trademark) can also be used.
As best shown in FIG. 3, the stator 64 of the alter-nator 62 consists of a hollow cylindrical tape wound core 71 of high permeability alloy steel to minimize hysteresis and eddy current losses. Toroidally wound about the core 71 are a pair of coils 73 serving as the stator winding. Such coils are selected to provide an output voltage as previously indi-cated and to match the impedance requirements of the down-stream electrical components such as the rectifier 70, volt-age regulator 72 and oscillator 74. The entire stator and winding assembly is encapsulated or potted to provide a mono-lithic type structure. The above described alternator 62 is of simple and rugged construction and is characterized by a low starting torque that permits the rapid attainment of an operating speed of about 15,000 r.p.m. in less than 1/4 second to effect delivery of 5 to 10 watts of power at a voltage level of about 12 volts.
The remaining components of the power supply are electrical in nature and are constituted of essentialIy con-ventional circuitry and circuit elements with the values of thé circuit eIements being selected to operate within the heretofore and hereinafter identified parameters. By way of illustrative example, FIG. 5 delineates a suitable circuit arrangement for the rectifier 70 and voltage regulator 72 that serves to convert the 8-16 volts r.m.s. alternating voltage output of alternator 62 into a constant DC voltage of about 8-12 volts in magnitude. As there shown, the alter-nator 62 is connected across a bridge rectifier 110 made up of solid state diodes 112. The bridge output is connected ,~
1 1620~ ~
across a zener diode 114 and a filtering capacitor 116 to provide a substantially constant DC output across terminals 118.
As described earler, the high frequency oscillator 74 is preferably designed to provide a square wave type out-put in the frequency range of from 10 to about 50 kilohertz at a voltage level commensurate with the previously indicated 8 to 12 volt DC input thereto. The high frequency alternat-ing output of the oscillator is then transformed up to a plus or minus 2,500 volt square wave for introduction into the first stage of the multiplier 80.
~ IG. 6 schematically illustrates a suitable circuit for such oscillator 74 and transformer 76. As shown, the output terminals 118 of the regulator 72 are connected across a resistor 120 and diode 122. The oscillator circuit in-cludes a pair of transistors 124, 126 having the output thereof connected across the primary winding 128 of trans-former 76. The stepped up voltage output of about + 2,500 volts at a frequency of from 10 to 50 kilohertz is delivered by the secondary winding 130 of the transformer.
Such preferred ~ 2,500 ~olt square wave output from the transformer 76 is applied to the input terminals of the long chain multiplier 80. Figure 7 schematically illustrates a suitable circuit for a multistage (suitably about 24 stages) series multiplier to provide a 60 kilovolt output.
Since the size and weight of any such unit is determined by the size and weight of the electrical elements, i.e~, capaci-tors and rectifiers, forming the multiplier chain, the plus or minus 2,500 volt input permits the utilization of standard 5 KV components which are diminutive in size and light in weight. As shownr such chain conventionally includes a plur-ality of stages each formed of series-connected capacitors 132 bridged by diodes 13~. Any type of series or parallel long chain multiplier may be employed although a series multiplier is presently preferred.
~ ;~
~ :l620~ ~
The air motor 52 and alternator 62 comprise a first subassembly of the cartridge 45 which is detachably electri-cally connected to a second subassembly comprising the recti-fier 70, voltage regulator 72, oscillator 74, and transformer 76. The long chain multiplier 80 (when potted) comprises a third subassembly which is detachably electrically connected to the transformer 76. The subassemblies may form separable monolithic-type structures that compositely form parts of the cartridge 45 and together are readily field-replaceable.
In order to limit the voltage output and to prevent over driving of the air motor 52l the air regulator assembly 27 is preferably included in line with the auxiliary air flow conduit 28 in handle 14. FIG. 8 schematically illustrates a simple air regulator assembly. As shown, a sleeve 150 defin-ing an elongate central bore 152 of markedly reduced air flow cross section is placed in the conduit 28. The bore 152 is capped by a displaceable valve member 154. The base portion 156 oE the valve member 154 is disposed in sliding inter-facial enga~ement with the walls of an enlarged portion of conduit 28 where suitable O-rings 158 are desirably inter-posed to prevent leakage of air therepast. The upper portion 160 of the valve member 154 is of reduced transverse extent to provide a chamber 162 thereabout. The chamber 162 is also bounded by a plug 164 having a central bore 166 of reduced air flow cross section. The plug 164 is located to limit upward displacement of the valve member 154 which is normally biased in closed inter~acial engagement therewith by the spring 168. Also included in the valve member 15~ are a ~plurality of angularly disposed conduits or channels 170 which permit air flow from the bore 152 to the chamber 162 when the dependent ends thereo~ are not closed by the end of the sleeve 150.
In operation of the subject unit, the valve member 154 is normally biased into sealing relation with the bore , .
1 ~620~ J
166 of the plug 16~. Air pressure extant within the chamber 162, howeverp will displace the valve member downwardly against the action of the biasing spring 168 serving to open the bore 166 and to partially or fully close the channels 170. The closure or partial closure of the channels 170 reverses the action and permits the spring 168 to control and move the plug upwardly. As will be apparent, proper dimen-sioning of the elements will serve to limit the effected pressure on the upstream side to a predetermined value inde-pendent of the pressure in the downstream line and thus regu-late the air input to the air motor.
Referring to FIG. 9, a modified air regulator assembly 27' is operative to selectively and independently regulate the flow of air via conduit 30 to the air cap Eor both atomization of the coating fluid and fan width control, while also effecting a selective control of the flow of air at substantially fixed pressure to conduit 28 to the energy conversion unit. The critical size and weight limitations attendant hand manipulable electrostatic spray guns narrowly confine permitted operating parameters necessary for high reliability and high efficiency operations. For example, the ability of the system to absorb and dissipate excess energy resulting from higher air supply pressure to the energy con-version unit is necessarily limited. Similarly a drop in supply air pressure results in less than desirable output voltages. Commensurately therewith, and because of the necessity of providing a constant pressure source of prime movant gas to the energy conversion unit, it is an equal necessity to provide a variable and controlled source of air ~or atomizing purposes. The control valve and regulator assembly 27' is adapted to be disposed within the gun for performing such necessary functions and it is readily con-trollable by the operator. Thus, the control valve and regu-lator assembly 27' serves the dual functions of regulating - \
1 ~B~
the flow of air fed, via conduit 30~ to the delivery end of the spray gun for use in atomization of the coating material and in fan spray pattern control and second of supplying air in controlled volumetric amounts and at substantially con-stant pressure to the air motor assembly.
As diagrammatically shown in FI5. 9, the control valve and regulator assembly 27' is adapted to be mounted within a bore 180 within the rear of the gun barrel, with such bore 180 being in fluid communication with air inlet conduit 26 and air conduits 28 and 30. Such assembly is formed of a selectively shaped cylindrical sleeve 182 thread-edly mounted in the bore 180, as at 184. The exposed end of the sleeve 182 terminates in a knob 186 for effecting longi-tudinal displacement of the sleeve 182 within bore 180 in response to rotation thereof. The forward end of sleeve 182 is tapered to provide a variable sized annular entry orifice 188 to the bore 180. The sleeve 182 includes a plurality of vent ports 190 near the forward end thereof.
Threadedly mounted, as at 192, within sleeve 182 is an elongate valve stem 1~4. The rear exposed end thereof terminates in a knob 196 for rotation relative to sleeve 182 and consequent longitudinal displacement of the pointed for-ward end 198 thereof relative to a restricted orifice 200 within the end of sleeve 182. Suitable O-rings 202 and 204 serve to selectively isolate air conduits 28 and 30 from each other.
In operation of the described assembly actuation of the trigger 24 results in air being supplied, from a remote source thereof and at a constant pressure, typically 70 psig, to air conduit 26. A portion of the air flows through the annuIar entry orifice 188, in an amount and at a pressure dependent upon the position of sleeve 182, and into conduit 30 for passage to the air cap for atomi~ation and fan control usage. The remainder of said air flows through the , . .
~16~
restricted orifice 200, when open, through ports 190 into the bore 180 and outwardly thereof through conduit 28. The flow through conduit 28 will be essentially at the pressure of the air source, typically 70 psig, and its volume rate of flow will be controlled by the size of the aperture 50 adjacent the air motor 52.
Rotation of knob 186 displaces the assembly forward or backward permitting a greater or lesser flow of air through the annular orifice 188 which exits through the port connecting with conduit 30 in the barrel of the spray gun and thereinafter to the air cap for atomization purposes. Inde-pendently of the operation of knob 186 just described rota-tion of knob 196 acts to move the inner concentric valve stem 194 back or forth opening or closing the second air passage 200. When knob 196 is rotated anticlockwise, the valve is in the open position and air at the full inlet pressure, typi-cally 70 psig/ is fed to the air motor via chamber 206. The screw threads and the fit of the O-rings 202 and 204 are preEerably designed so that rotation of knob 196 rotates only valve stem 194 and not the body 182, thus permitting control of power for electrostatic spraying without affecting the setting of air for atomization. Similar rotation of knob 186 to control atomization does not affect the relative setting of the valve stem 194 and valve seat 208 and so does not simultaneously actuate the air supply to the air motor via port 188.
A prototype system constructed in accord with the foregoing principles readily provides a 55 KV output at 3 watts DC from a 20 psig regulated compressed air input at 4.2 scfm. The following operational and physical parameters were attained:
Air Mot_r - Alternator Subassembly .
Air Input 20 psig; 4.2 scfm Output 8.6 watts at 12.1 volt rms and 250 hertz Dimensions (D x L) 1.375" x 1.355"
Weight 2.4 oz.
Rise Time less than 0.1 sec. to 90~ of rated power Rectifier-Regulator-Oscillator-Transformer Input as above Output 5.1 KV (peak) at 20 KHz and 5.4 watts Dimensions 1.375" x 1.0l' Weight 2.25 oz. (encapsulated) High Voltage Multiplier Input as above Output 55 KV at 3 watts DC
Dimensions (D x L) 0.875" x 4.75"
Weight 4.0 oz. (encapsulated~
,., :: ' ~
~ ' ` . ' ' . . ' ~ '
The electrode system incorporated in the air cap 32 may also be con~entional, as is the grounding of the conductive handle portion 14, by means of a conductive sheath 44 disposed around the air hose 16 or by means of a suitable ground lead associated there~ith.
, 1:l62043 Disposed within the barrel portion 12 and the upper section o~ the handle portion 14 of the gun 10 is an elongate removable power supply cartridge member ~5. The cartridge member 45 contains the hereinafter-described operative com-ponents of the power supply and is of generally cylindrical configuration having a rear section 46 of appreciably greater diameter than its forward section 48.
When the cartridge 45 is properly seated within its complementarily contoured receiving bore within the gun bar-rel 12, the auxiliary air flow conduit 28 is directly con-nected to an input nozzle 50 of a diminutive air motor assembly 52 to rotatably drive the rotor 56 thereof at high speed. The air flow through the air motor 52 may suitably be vented to the atmosphere through an exhaust channel 54 at the rear of the gun barrel 12. The rotor 56 of the air motor 52 is mounted on a common shaft 58 with the armature 60 of an adjacent alternator 62 to form an effectively integral low inertia assembly capable of rapid acceleration to high speeds with a concomitant long life. The armature 60 is disposed within a cylindrical epoxy-coated sleeve type stator 64, preferably of tape wound construction. The air motor 52 and the alternator 62 comprise an essentially integral sub-assembly that is both of small size, lightweight and low ~inertia. The described direct coupling of the air motor 52 with the alternator 62 operates to effect a direct conversion of kinetic energy available in the moving air stream in con-dui~t 28 into electrical energy in the nature of an alternat-ing voltage suitably of about 8-20 volts r.m.s. at a frequen-cy sf about 250 to 350 cycles/sec.
The alternating voltage output of the alternator 62 is introduced, through leads 68, into a rectifier 70 and voltage regulator 72 wherein it is converted into a substan-tially constant DC voltage, suitably of about 8 to 20 volts in magnitude. The regulated output voltage of rectifier 72 .:
' :
2~ ~
drives a high frequency oscillator 74 to produce a low volt-age sine or square wave output suitably at a frequency in the range of from 10 to 50 kilohertz. The high frequency but low voltage output of the oscillator 74 is then raised by a transformer 76 which comprises an integral part of the oscil-lator circuit, to provide a + 2,500 volt square or sine wave output at the specified frequency range.
The high frequency, high voltage output of the transformer 76 is introduced into a long chain multiplier 80, suitably a series multiplier of about 20 or more stages, to elevate the input voltage into a desired 30 to 100 kilovolt rectified output voltage which is fed to the electrode assembly in the air cap 32 via lead 84 and a limiting resist-ance 82. A major part of limiting resistance 82 may alter-natively be placed between the low voltage end of cartridge 45 and the grounded handle 14.
The critical size and weight limitations herein attendant for electrostatic spray coating apparatus, and par-ticularly for hand manipulatable spray guns, can be effec-tively satisfied by utilization of a prime movant air supply and flow system of the type schematically illustrated in FIG.
lA. As there shown, the prime movant source comprises a con-ventional plant compressed air supply 85 that normally sup-plies clean air at pressures greater than 70 ps.ig and at available flow rates in excess of 15 scfm. Such compressed air is initially introduced into an externally located, con-ventional and commercially available pressure regulator 86 adapted to provide a fixed and regulated supply of compressed air at 70 psig. A suitable regulator may, for exa~ple, be Binks No. 85-201 as manufactured and sold by Binks Manufac-turing Company of Franklin Park, Illinois. Such regulated air at 70 psig is introduced via the air hose 16 to the gun 10. Previous limitations on the effective length of air hose for electrostatic spray apparatus, which was about 25 feet, ~ ~2~ 1 are now effectively removed and any length of air hose can now be employed. Air flow within the gun is primarily con-trolled by actuation of the trigger 24 and shift of the flow control valve 22 disposed within conduit 20 in the handle 14 from fully closed to fully opened condition. Downstream of trigger 24 the primary air flow within conduit 26 is intro-duced into the control valve and regulator assembly 27. Such control valve and regulator assembly 27 is operative to selectively and independently regulate the flow of air via conduit 30 to the air cap for both atomization of the coating fluid and fan width control, while also effecting a selective control of the flow of air at substantially fixed pressure to conduit 28 to the energy conversion unit.
As mentioned earlier, spray guns of the type herein of concern employable in commercial electrostatic paint spraying or other coating operations must satisfy and fall within a practical and established framework of mechanical and electrical parameters. In general, hand-holdable electrostatic spray guns desirably should weigh less than three pounds, should provide an operating potential of from 30 to 100 kilovolts at a current level of about 50 micro-amperes, and should be operable with conventional plant supply of compressed air at pressures from about 20 to 80 psig. In addition, such guns must include means for limiting the current flow to prevent deleterious arc-type discharge when the high voltage electrode approaches a grounded object.
The following portions of this specification will describe, in more detail, a presently preferred embodiment of a self-contained electrical power supply for electrostatic spray guns that (a) weighs about 1/2 pound, (b) is operable from conventionally available compressed air supplies of from 20 to 80 psig at a flow rate no greater than 5 scfm, (c) pro-vides a 50 kilovolt minimum output at 50 microamperes with a maximum current flow of about 200 microamperes at short 1 1~20~ ~
circuit, and (d) is conveniently formed as a replaceable cartridge to facilitate field servicing of the spray equipment--all of which permit ready cartridge-type incorpo-ration within hand-holdable spray guns and concomi~ant satis-faction of the currently accepted and recognized mechanical and electrical parameters therefor.
Further, there is also described a presently pre-ferred embodiment of a lightweight energy conversion assembly for electrostatic spray guns that (a) is operable from con-ventionally available compressed air supplies of about 70 psig at flow rates of about 3 scfm, (b) provides an 8-20 volt alternating output at 5-10 watts/ (c) provides desired output voltage to satisfy electrostatically enhanced deposition of spray coating material, and (d) is conveniently formed as a separable component of a replaceable cartridge assembly to facilitate field servicing of the spray equipment.
The air motor 52, alternator 62, rectifier 70 and voltage regulator 72 subassembly preferably is desirably con-structed to provide exemplary operating characteristics such as (a) relatively constant output voltage of 5-10 volts DC at a power level of 5-10 watts from a 20-80 psig oil-free air supply utilizing less than 5 scfm of compressed air exhaust-ing at atmosphere pressure, (b) acceleration of the air motor rotor 56 and armature 60 to 80% of full speed within a maxi-mum of about 0.2 second from trigger actuation, and (c) a light weight, in the order of 3 ounces, with a concomitant structural durability to provide for long operating life.
As best shown in FIGS. 2 and 3, a presently pre-ferred construction for the air motor 52 comprises a simple impulse type air motor wherein the rotor 56, when exposed to an entering air stream through nozzle 50 moving at about 300 meters/sec., has a theoretical maximum speed of about 300,000 r.p.m. so as to conveniently and readily permit operation at speeds in the order of 10,000 to 30,000 r.p.m. while provid-ing the necessary torque to drive the alternator 62 in such ~ I~62~41 manner as to provide the desired power output from the avail-able kinetic energy in the moving air stream.
Compressed air flowing at about 4 scfm at a pressure of 40 psig has a theoretical power capability of about 200 watts, and at flow conditions of about 3 scfm at a pressure of 70 psig, it has a theoretical power capability of about 250 watts. Since the desired output of the alternator 62 and the rectifier 70 are in the order of about 10 watts or less, the described system renders the full pressure drop available to drive the air motor 52 and associated alternator 62.
~dditionally, the above described preferred impulse turbine type of air motor avoids the utilization of sliding seals and permits the use of ball bearings, oil-impregnated bushings or other suitable bearing elements, suitably of the type em-ployed in dentists' drills and the like for long-lived high speed operation.
In order to obtain the desired rapid acceleration of the~armature 60 of the alternator 62, the inertia of the air motor rotor 56 and armature 60 must be kept as small as pos-sible.
To the above ends, the rotor 56 of the air motor 52 is about 2~5 cm. in diameter, about 0.6 cm. thick and is con-veniently of lightweight, high strength resin such as "Delrin"
(a trademark), manufactured by E.~I. DuPont de Nemours & Co., Inc. The rotor 56 is mounted adjacent one end of shaft 58 which is terminally supported in sealed ball bearings 59.
The ball bearing-mounted rotor 56 is disposed in close peripheral clearance within a chamber 61 formed in a shell ~houslng 63. The prime movant air from conduit 28 is intro-duce~d through a selectively located and sized orifice 50 that is e~ssentially tangentially oriented relative to the rotor periphery and is about 0.15 cm. in diameter. The diameter of the aperture 50 is selected to provide air exiting into cham-ber 61 in the vicinity of sonic velocity and to limit flow to 0~1 approximately 3 scfm. After impingement on the blade sur-faces of rotor 56, such air is vented from chamber 61 through one or preferably a number of ports 54. Disposed downstream of the ports 54 is a muffler plate 67 disposed in peripheral engagement with an o-ring 69, for venting such exiting air to the atmosphere from the rear of the gun with minimal noise.
A suitable muffler 67 comprises a sintered ceramic or metal disc of about 0.3 cm. thickness.
As shown in FIG~ 4, the torque speed characteristic of the described impulse type turbine, shows that output torque is essentially inversely proportional to speed of rotation. As such, desirable torque levels are achieved at speeds of less than 30,000 r.p.m. as represented by the shaded portion under the curve. Such torque-speed limitation poses a further operating parameter upon the design of the alternator 62.
The alternator unit functions to convert the rota-tional kinetic energy of the air motor rotor 56 into electri-cal energy, which in turn serves as the electrical power source for the high voltage for the electrostatically en-hanced deposition o~ the spray coating material. As previ-ously described, such alternator unit should provide a power output of from 5 to 10 watts at an output voltage of at least 5, and preferably greater than 10 volts, and should do so with low losses and internal dissipation and in a highly reliable manner through avoidance of any brushes, wipers or other commutating means. The above ob]ectives must be satis-fied in an assembly that is both small in size and weight and is possessed of minimal inertia.
To the above ends, the alternator 62 is disposed immediately adjacent to the rotor 56 and within the common housing 63. The armature 60 is mounted on shaft 58 and is directly driven by rotor 56. Such armature 60 preferably comprises a high energy permanent magnet 100 about 5/8 inch 204 ~ `~
long and about 1/2 inch in diameter, magnetized across a diameter thereof. Present knowledge indicates that magnet diameters in excess of 1/2 inch are attended by unaccep~able inert~a charactexistics. Alinc~ 8 Ca tradem~xk~ is a preferred material for such magnet armature although ~t~er mater~als including Aln~co 5 (a trademark) can also be used.
As best shown in FIG. 3, the stator 64 of the alter-nator 62 consists of a hollow cylindrical tape wound core 71 of high permeability alloy steel to minimize hysteresis and eddy current losses. Toroidally wound about the core 71 are a pair of coils 73 serving as the stator winding. Such coils are selected to provide an output voltage as previously indi-cated and to match the impedance requirements of the down-stream electrical components such as the rectifier 70, volt-age regulator 72 and oscillator 74. The entire stator and winding assembly is encapsulated or potted to provide a mono-lithic type structure. The above described alternator 62 is of simple and rugged construction and is characterized by a low starting torque that permits the rapid attainment of an operating speed of about 15,000 r.p.m. in less than 1/4 second to effect delivery of 5 to 10 watts of power at a voltage level of about 12 volts.
The remaining components of the power supply are electrical in nature and are constituted of essentialIy con-ventional circuitry and circuit elements with the values of thé circuit eIements being selected to operate within the heretofore and hereinafter identified parameters. By way of illustrative example, FIG. 5 delineates a suitable circuit arrangement for the rectifier 70 and voltage regulator 72 that serves to convert the 8-16 volts r.m.s. alternating voltage output of alternator 62 into a constant DC voltage of about 8-12 volts in magnitude. As there shown, the alter-nator 62 is connected across a bridge rectifier 110 made up of solid state diodes 112. The bridge output is connected ,~
1 1620~ ~
across a zener diode 114 and a filtering capacitor 116 to provide a substantially constant DC output across terminals 118.
As described earler, the high frequency oscillator 74 is preferably designed to provide a square wave type out-put in the frequency range of from 10 to about 50 kilohertz at a voltage level commensurate with the previously indicated 8 to 12 volt DC input thereto. The high frequency alternat-ing output of the oscillator is then transformed up to a plus or minus 2,500 volt square wave for introduction into the first stage of the multiplier 80.
~ IG. 6 schematically illustrates a suitable circuit for such oscillator 74 and transformer 76. As shown, the output terminals 118 of the regulator 72 are connected across a resistor 120 and diode 122. The oscillator circuit in-cludes a pair of transistors 124, 126 having the output thereof connected across the primary winding 128 of trans-former 76. The stepped up voltage output of about + 2,500 volts at a frequency of from 10 to 50 kilohertz is delivered by the secondary winding 130 of the transformer.
Such preferred ~ 2,500 ~olt square wave output from the transformer 76 is applied to the input terminals of the long chain multiplier 80. Figure 7 schematically illustrates a suitable circuit for a multistage (suitably about 24 stages) series multiplier to provide a 60 kilovolt output.
Since the size and weight of any such unit is determined by the size and weight of the electrical elements, i.e~, capaci-tors and rectifiers, forming the multiplier chain, the plus or minus 2,500 volt input permits the utilization of standard 5 KV components which are diminutive in size and light in weight. As shownr such chain conventionally includes a plur-ality of stages each formed of series-connected capacitors 132 bridged by diodes 13~. Any type of series or parallel long chain multiplier may be employed although a series multiplier is presently preferred.
~ ;~
~ :l620~ ~
The air motor 52 and alternator 62 comprise a first subassembly of the cartridge 45 which is detachably electri-cally connected to a second subassembly comprising the recti-fier 70, voltage regulator 72, oscillator 74, and transformer 76. The long chain multiplier 80 (when potted) comprises a third subassembly which is detachably electrically connected to the transformer 76. The subassemblies may form separable monolithic-type structures that compositely form parts of the cartridge 45 and together are readily field-replaceable.
In order to limit the voltage output and to prevent over driving of the air motor 52l the air regulator assembly 27 is preferably included in line with the auxiliary air flow conduit 28 in handle 14. FIG. 8 schematically illustrates a simple air regulator assembly. As shown, a sleeve 150 defin-ing an elongate central bore 152 of markedly reduced air flow cross section is placed in the conduit 28. The bore 152 is capped by a displaceable valve member 154. The base portion 156 oE the valve member 154 is disposed in sliding inter-facial enga~ement with the walls of an enlarged portion of conduit 28 where suitable O-rings 158 are desirably inter-posed to prevent leakage of air therepast. The upper portion 160 of the valve member 154 is of reduced transverse extent to provide a chamber 162 thereabout. The chamber 162 is also bounded by a plug 164 having a central bore 166 of reduced air flow cross section. The plug 164 is located to limit upward displacement of the valve member 154 which is normally biased in closed inter~acial engagement therewith by the spring 168. Also included in the valve member 15~ are a ~plurality of angularly disposed conduits or channels 170 which permit air flow from the bore 152 to the chamber 162 when the dependent ends thereo~ are not closed by the end of the sleeve 150.
In operation of the subject unit, the valve member 154 is normally biased into sealing relation with the bore , .
1 ~620~ J
166 of the plug 16~. Air pressure extant within the chamber 162, howeverp will displace the valve member downwardly against the action of the biasing spring 168 serving to open the bore 166 and to partially or fully close the channels 170. The closure or partial closure of the channels 170 reverses the action and permits the spring 168 to control and move the plug upwardly. As will be apparent, proper dimen-sioning of the elements will serve to limit the effected pressure on the upstream side to a predetermined value inde-pendent of the pressure in the downstream line and thus regu-late the air input to the air motor.
Referring to FIG. 9, a modified air regulator assembly 27' is operative to selectively and independently regulate the flow of air via conduit 30 to the air cap Eor both atomization of the coating fluid and fan width control, while also effecting a selective control of the flow of air at substantially fixed pressure to conduit 28 to the energy conversion unit. The critical size and weight limitations attendant hand manipulable electrostatic spray guns narrowly confine permitted operating parameters necessary for high reliability and high efficiency operations. For example, the ability of the system to absorb and dissipate excess energy resulting from higher air supply pressure to the energy con-version unit is necessarily limited. Similarly a drop in supply air pressure results in less than desirable output voltages. Commensurately therewith, and because of the necessity of providing a constant pressure source of prime movant gas to the energy conversion unit, it is an equal necessity to provide a variable and controlled source of air ~or atomizing purposes. The control valve and regulator assembly 27' is adapted to be disposed within the gun for performing such necessary functions and it is readily con-trollable by the operator. Thus, the control valve and regu-lator assembly 27' serves the dual functions of regulating - \
1 ~B~
the flow of air fed, via conduit 30~ to the delivery end of the spray gun for use in atomization of the coating material and in fan spray pattern control and second of supplying air in controlled volumetric amounts and at substantially con-stant pressure to the air motor assembly.
As diagrammatically shown in FI5. 9, the control valve and regulator assembly 27' is adapted to be mounted within a bore 180 within the rear of the gun barrel, with such bore 180 being in fluid communication with air inlet conduit 26 and air conduits 28 and 30. Such assembly is formed of a selectively shaped cylindrical sleeve 182 thread-edly mounted in the bore 180, as at 184. The exposed end of the sleeve 182 terminates in a knob 186 for effecting longi-tudinal displacement of the sleeve 182 within bore 180 in response to rotation thereof. The forward end of sleeve 182 is tapered to provide a variable sized annular entry orifice 188 to the bore 180. The sleeve 182 includes a plurality of vent ports 190 near the forward end thereof.
Threadedly mounted, as at 192, within sleeve 182 is an elongate valve stem 1~4. The rear exposed end thereof terminates in a knob 196 for rotation relative to sleeve 182 and consequent longitudinal displacement of the pointed for-ward end 198 thereof relative to a restricted orifice 200 within the end of sleeve 182. Suitable O-rings 202 and 204 serve to selectively isolate air conduits 28 and 30 from each other.
In operation of the described assembly actuation of the trigger 24 results in air being supplied, from a remote source thereof and at a constant pressure, typically 70 psig, to air conduit 26. A portion of the air flows through the annuIar entry orifice 188, in an amount and at a pressure dependent upon the position of sleeve 182, and into conduit 30 for passage to the air cap for atomi~ation and fan control usage. The remainder of said air flows through the , . .
~16~
restricted orifice 200, when open, through ports 190 into the bore 180 and outwardly thereof through conduit 28. The flow through conduit 28 will be essentially at the pressure of the air source, typically 70 psig, and its volume rate of flow will be controlled by the size of the aperture 50 adjacent the air motor 52.
Rotation of knob 186 displaces the assembly forward or backward permitting a greater or lesser flow of air through the annular orifice 188 which exits through the port connecting with conduit 30 in the barrel of the spray gun and thereinafter to the air cap for atomization purposes. Inde-pendently of the operation of knob 186 just described rota-tion of knob 196 acts to move the inner concentric valve stem 194 back or forth opening or closing the second air passage 200. When knob 196 is rotated anticlockwise, the valve is in the open position and air at the full inlet pressure, typi-cally 70 psig/ is fed to the air motor via chamber 206. The screw threads and the fit of the O-rings 202 and 204 are preEerably designed so that rotation of knob 196 rotates only valve stem 194 and not the body 182, thus permitting control of power for electrostatic spraying without affecting the setting of air for atomization. Similar rotation of knob 186 to control atomization does not affect the relative setting of the valve stem 194 and valve seat 208 and so does not simultaneously actuate the air supply to the air motor via port 188.
A prototype system constructed in accord with the foregoing principles readily provides a 55 KV output at 3 watts DC from a 20 psig regulated compressed air input at 4.2 scfm. The following operational and physical parameters were attained:
Air Mot_r - Alternator Subassembly .
Air Input 20 psig; 4.2 scfm Output 8.6 watts at 12.1 volt rms and 250 hertz Dimensions (D x L) 1.375" x 1.355"
Weight 2.4 oz.
Rise Time less than 0.1 sec. to 90~ of rated power Rectifier-Regulator-Oscillator-Transformer Input as above Output 5.1 KV (peak) at 20 KHz and 5.4 watts Dimensions 1.375" x 1.0l' Weight 2.25 oz. (encapsulated) High Voltage Multiplier Input as above Output 55 KV at 3 watts DC
Dimensions (D x L) 0.875" x 4.75"
Weight 4.0 oz. (encapsulated~
,., :: ' ~
~ ' ` . ' ' . . ' ~ '
Claims (31)
1. An electrostatic spray coating device devoid of external electrical power connection thereto comprising:
means for emitting a spray of atomized coating material, electrode means disposed adjacent the locus of atomization of said coating material for applying an electric charge to said atomized coating material, and a self-contained electrical potential originat-ing power supply for providing the operating voltage for said electrode means, said self-contained electrical potential originating power supply including, means for converting the kinetic energy of a moving air stream derived from a remote source thereof into an alternating voltage, and long chain voltage multiplying means for con-verting said alternating voltage into a high DC potential voltage for application to said electrode means.
means for emitting a spray of atomized coating material, electrode means disposed adjacent the locus of atomization of said coating material for applying an electric charge to said atomized coating material, and a self-contained electrical potential originat-ing power supply for providing the operating voltage for said electrode means, said self-contained electrical potential originating power supply including, means for converting the kinetic energy of a moving air stream derived from a remote source thereof into an alternating voltage, and long chain voltage multiplying means for con-verting said alternating voltage into a high DC potential voltage for application to said electrode means.
2. A device as set forth in claim 1 wherein said kinetic energy converting means includes an air turbine driven alternator and a transformer for raising the magnitude of said alternating voltage before application thereof to said voltage multiplying means.
3. Electrostatic spray coating apparatus devoid of external electrical power connection thereto comprising:
means for emitting a spray of atomized coating material, electrode means disposed adjacent the locus of atomization of said coating material for applying an elec-trical charge to said atomized coating material, a self contained potential originating power supply for providing the operating voltage for said electrode means, said self-contained electrical potential originating power supply including, means for converting the kinetic energy of a moving stream of air derived from a remote source thereof into an alternating voltage of low magnitude, means for converting said low magnitude alter-nating voltage into a substantially constant magnitude DC
voltage, oscillator means responsive to said substanti-ally constant magnitude DC voltage for providing a high fre-quency, high magnitude, alternating voltage output, and long chain voltage multiplying means for con-verting the high frequency, high magnitude output of said oscillator means into a DC voltage of substantially higher magnitude for application to said electrode means.
means for emitting a spray of atomized coating material, electrode means disposed adjacent the locus of atomization of said coating material for applying an elec-trical charge to said atomized coating material, a self contained potential originating power supply for providing the operating voltage for said electrode means, said self-contained electrical potential originating power supply including, means for converting the kinetic energy of a moving stream of air derived from a remote source thereof into an alternating voltage of low magnitude, means for converting said low magnitude alter-nating voltage into a substantially constant magnitude DC
voltage, oscillator means responsive to said substanti-ally constant magnitude DC voltage for providing a high fre-quency, high magnitude, alternating voltage output, and long chain voltage multiplying means for con-verting the high frequency, high magnitude output of said oscillator means into a DC voltage of substantially higher magnitude for application to said electrode means.
4. Electrostatic spray apparatus as set forth in claim 3 wherein said kinetic energy converting means includes rotatable turbine means drivable by a stream of air from said compressed source thereof and an alternator driven by said turbine means.
5. Electrostatic spray apparatus as set forth in claim 3 wherein said means for converting said low magnitude alternating voltage into a substantially constant magnitude DC voltage includes a rectifier and a voltage regulator.
6. Electrostatic spray apparatus as set forth in claim 3, wherein said voltage multiplying means is a multi-stage series multiplier circuit.
7. Electrostratic spray apparatus as set forth in claim 4, wherein said turbine means further comprises an impulse-type air motor.
8. Electrostatic spray apparatus as set forth in claim 4, wherein said alternator driven by said turbine means includes a solid magnet armature directly connected to said turbine means.
9. Electrostatic spray coating apparatus devoid of external electrical power connection thereto comprising:
means for emitting a spray of atomized coating material, electrode means disposed adjacent the locus of atomization of said coating material for applying an electri-cal charge to said atomized coating material, a self-contained electrical potential originat-ing power supply for providing the operating voltage for said electrode means, said self-contained potential originating electrical power supply including, air driven low inertia turbine means for con-verting the kinetic energy of a moving stream of air into a low frequency, low magnitude alternating voltage, means for converting said low frequency, low magnitude alternating voltage into a substantially constant DC voltage of low magnitude, an oscillator responsive to said DC low magni-tude voltage for providing a high frequency alternating volt-age output, step-up transformer means associated with said oscillator for delivering a high magnitude alternating volt age at the output frequency of said oscillator, and long chain voltage multiplying means for con-verting the output of said transformer means into a DC volt-age of still higher magnitude for application to said elec-trode means.
means for emitting a spray of atomized coating material, electrode means disposed adjacent the locus of atomization of said coating material for applying an electri-cal charge to said atomized coating material, a self-contained electrical potential originat-ing power supply for providing the operating voltage for said electrode means, said self-contained potential originating electrical power supply including, air driven low inertia turbine means for con-verting the kinetic energy of a moving stream of air into a low frequency, low magnitude alternating voltage, means for converting said low frequency, low magnitude alternating voltage into a substantially constant DC voltage of low magnitude, an oscillator responsive to said DC low magni-tude voltage for providing a high frequency alternating volt-age output, step-up transformer means associated with said oscillator for delivering a high magnitude alternating volt age at the output frequency of said oscillator, and long chain voltage multiplying means for con-verting the output of said transformer means into a DC volt-age of still higher magnitude for application to said elec-trode means.
10. Electrostatic spray apparatus as set forth in claim 9, wherein said kinetic energy converting means in-cludes an impulse type, rotatable turbine drivable by a stream of air from a compressed source thereof, and an alter-nator driven by said turbine adapted to provide an output voltage of about 12 volts at a frequency of about 250 hertz.
11. Electrostatic spray apparatus as set forth in claim 9, wherein said means for converting said low frequen-cy, low magnitude alternating voltage includes a rectifier and a voltage regulator adapted to provide a DC output volt-age of about 10 volts.
12. Electrostatic spray apparatus as set forth in claim 9, wherein said oscillator is adapted to provide an alternating output voltage at a frequency in the range of from 10 to 50 kilohertz.
13. Electrostatic spray apparatus as set forth in claim 9, wherein said transformer means is adapted to provide an alternating output of about plus or minus 2,500 volts.
14. Electrostatic spray apparatus as set forth in claim 9, wherein said voltage multiplying means is a multi-stage series multiplier circuit adapted to provide an output voltage in the range of from 30 to 100 kilovolts.
15. Electrostatic spray apparatus as set forth in claim 10, wherein said alternator driven by said turbine means includes a solid magnet armature directly connected to said turbine means.
16. Electrostatic spray apparatus as set forth in claim 9, wherein said alternating voltage converting means and oscillator means are encapsulated to form a first mono-lithic cartridge subassembly.
17. Electrostatic spray apparatus as set forth in claim 9, wherein said voltage multiplying means is encapsu-lated to form a second monolithic cartridge subassembly.
18. Electrostatic spray apparatus as set forth in claim 9, wherein said kinetic energy converting means com-prises a first monolithic subassembly, said alternating volt-age converting means, oscillator means and transformer means comprises a second monolithic subassembly, said voltage mul-tiplying means comprises a third monolithic subassembly and said first, second and third subassemblies comprise a readily assemblable and disassemblable cartridge.
19. In an electrostatic spray coating apparatus in-corporating means for emitting a spray of coating material and electrode means for applying an electric charge to the emitted coating material, a self-contained electrical poten-tial originating power supply devoid of external electrical power connection thereto for providing the operating voltage for said electrode means comprising:
means for converting the kinetic energy of a moving gas stream derived from a remote source thereof into kinetic energy of a rotating solid, and means for converting the kinetic energy of said rotating solid into electrical energy for application to said electrode means.
means for converting the kinetic energy of a moving gas stream derived from a remote source thereof into kinetic energy of a rotating solid, and means for converting the kinetic energy of said rotating solid into electrical energy for application to said electrode means.
20. Electrostatic spray apparatus as set forth in claim 19, wherein said last mentioned means is an alternator providing a low frequency, low magnitude alternating voltage output, and said apparatus further comprises, means for converting said low frequency, low magni-tude alternating voltage into a substantially constant magni-tude DC voltage, oscillator means responsive to said DC voltage for providing a high frequency, high voltage alternating voltage output, and long chain voltage multiplying means for converting the output of said oscillator means into a DC potential of still higher magnitude for application to said electrode means.
21. In an electrostatic spray coating gun adapted to be connected to a source of fluid under pressure and to emit a spray of coating material including electrode means for applying an electric charge to the emitted coating mater-ial, a self-contained electrical power supply for provid-ing the sole source of electrical potential to said electrode means, said self-contained electrical power supply compris-ing means for converting a portion of the energy of a fluid under pressure to an alternating voltage, and long chain voltage multiplying means for converting said alternating voltage into a high direct current poten-tial, sufficient for use in electrostatic spraying, for application to said electrode means.
22. In an electrostatic spray coating gun as set forth in claim 21:
said self-contained electrical power supply comprising a first monolithic subassembly for converting a por-tion of the energy of a fluid under pressure to an alternat-ing voltage, a second monolithic subassembly for converting said alternating voltage into a higher magnitude and higher fre-quency alternating voltage output, and a third monolithic subassembly for converting said higher magnitude and higher frequency alternating voltage output into a high direct current potential, sufficient for use in electrostatic spraying, for application to said electrode means, said first, second and third subassemblies being interconnected to provide a cartridge which is removably insertable in said electrostatic spray coating gun.
said self-contained electrical power supply comprising a first monolithic subassembly for converting a por-tion of the energy of a fluid under pressure to an alternat-ing voltage, a second monolithic subassembly for converting said alternating voltage into a higher magnitude and higher fre-quency alternating voltage output, and a third monolithic subassembly for converting said higher magnitude and higher frequency alternating voltage output into a high direct current potential, sufficient for use in electrostatic spraying, for application to said electrode means, said first, second and third subassemblies being interconnected to provide a cartridge which is removably insertable in said electrostatic spray coating gun.
23. In electrostatic spray apparatus as set forth in claim 19 wherein said means for converting the kinetic energy of a moving gas stream comprises:
rotatable turbine means peripherally exposed to a stream of air moving at high speed for converting the kinetic energy of said stream of air into kinetic energy of a rotating solid, said means for converting the kinetic energy of said rotating solid including alternator means having a common axis of rotation with said turbine means and directly driven thereby to jointly constitute said rotating solid for converting the kinetic energy of said rotating solid into electrical energy.
rotatable turbine means peripherally exposed to a stream of air moving at high speed for converting the kinetic energy of said stream of air into kinetic energy of a rotating solid, said means for converting the kinetic energy of said rotating solid including alternator means having a common axis of rotation with said turbine means and directly driven thereby to jointly constitute said rotating solid for converting the kinetic energy of said rotating solid into electrical energy.
24. Apparatus as set forth in claim 21, wherein said turbine means comprises an impulse type air motor.
25. Apparatus as set forth in claim 21, wherein said alternator means includes a solid magnet armature magnetized across a diameter thereof.
26. Apparatus as set forth in claim 21, wherein said alternator means includes a stator comprising a tape wound core having at least a pair of coils toroidally wound thereabout.
27. Apparatus as set forth in claim 21, wherein said rotating mass is acceleratable from rest to an operating speed of over 10,000 r.p.m. in less than 1/4 second.
28. Apparatus as set forth in claim 21, wherein said alternator means is adapted to provide a power output of from 5 to 10 watts at an output voltage of at least 5 volts within 1/4 second after starting from rest.
29. In electrostatic spray coating apparatus having a self-contained electrical power supply devoid of external electrical connections thereto, means for converting the kinetic energy of a moving air stream into electrical energy comprising, an impulse type air motor having a low moment of inertia for converting the kinetic energy of a moving air stream from a remote source thereof into kinetic energy of a rotating mass and alternator means having a solid magnet armature of low moment of inertia and magnetized across a diameter thereof, disposed coaxially with said air motor and directly driven thereby, said air motor and alternator means jointly consti-tuting a low moment of inertia rotatable mass acceleratable from rest to an operating speed of over 10,000 r.p.m. in less than 1/4 second for rapidly converting the kinetic energy of said stream of air into alternating electrical energy suit-able for use as a primary electrical power source for said electrostatic spray coating apparatus.
30. Apparatus as set forth in claim 28, including control and regulating means disposed intermediate said air motor and said remote source of said stream of air for effecting a constant flow of said air to said turbine means at a fixed pressure and of a kinetic energy content to pro-vide an alternating electrical power output from said alter-nator of at least 5 watts.
31. Energy conversion apparatus for effecting the rapid conversion of the kinetic energy of a moving stream of air into electrical energy comprising, a perimetric housing defining a pair of coaxially aligned cylindrical chambers therewithin, rotatable turbine means having a low moment of inertia disposed in one of said chambers, alternator means having a rotor with a low moment of inertia on a common axis of rotation with said turbine means and adapted to be directly driven thereby disposed in said second chamber, said turbine means and alternator means jointly constituting a composite low moment of inertia rotatable mass acceleratable from rest to an operating speed of over 10,000 r.p.m. in less than 1/4 second, means for directing a stream of air moving at high speed into said first chamber into driving engagement with said turbine means to convert the kinetic energy of said air stream into kinetic energy of rotation of said turbine means and alternator rotor, and stator means included in said alternator means and forming at least a portion of the defining walls of said second chamber for converting the kinetic energy of said rotating rotor into electrical energy.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000345425A CA1162041A (en) | 1980-02-12 | 1980-02-12 | Electrostatic spray coating apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000345425A CA1162041A (en) | 1980-02-12 | 1980-02-12 | Electrostatic spray coating apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162041A true CA1162041A (en) | 1984-02-14 |
Family
ID=4116220
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000345425A Expired CA1162041A (en) | 1980-02-12 | 1980-02-12 | Electrostatic spray coating apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1162041A (en) |
-
1980
- 1980-02-12 CA CA000345425A patent/CA1162041A/en not_active Expired
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