A hand-manipulable electrostatic spray gun is disclosed which is one requiring no electric cable attached to it. Within the hand-manipulable spray gun an air turbine is driven at high speed in the order of 60,000 rpm and drives directly an alternator to generate an alternating voltage in the order of 50 volts at about 1000 Hz. The output of this alternator is supplied to a step-up transformer to achieve a secondary voltage in the order of 2500 volts. From here, it is supplied to a long chain series voltage multiplier to increase the voltage thereof to one in the order of 55-80 kilovolts. The combination of a relatively small transformer and small capacitance establishes a direct voltage output from the voltage multiplier which has an alternating voltage ripple in excess of fifteen percent. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.
An electrostatic air atomization spray coating system having a hand held spray gun, wherein a flow of air to the gun is sensed to control energization of a high voltage power supply for electrostatically charging spray particles, is characterized by a bypass valve on the spray gun which selectively permits air atomization spraying with or without electrostatics.
A pneumatic system is disclosed for regulating the acceleration and running speed of an air turbine and alternator used in electrostatic spray apparatus having a self-contained electrical power supply. The air turbine includes a rotor which is arranged to be biased in a first direction of rotation by a flow of impinging drive air and in a second opposite direction by a flow of impinging brake air. The flows of air cooperatively result in rotation of the turbine in a desired direction of operation and enable a minimized period of acceleration for a predetermined running speed.
An electrostatic spray gun having a rotatable voltage generator for providing electrical energy at low voltage for conversion within the spray gun into electrostatic high voltage energy, wherein a rotating voltage generator is driven by an air turbine under the influence of a pressurized input air supply, the pressurized air passing through conduits in the handle of the spray gun, an air valve actuated by a trigger, an air flow regulator, and into impinging contact against rotatable turbine blades. The air supply is exhausted from the spray gun through internal passages which provide cooling air to the electrical components within the spray gun, and through further passages opening from the bottom of the spray gun handle which minimize the audible noise caused by such air flow.
An electrostatic spray gun for the application of paints and other coatings has a high voltage power supply having a contact at the front end thereof. A flange on the end of the power supply surrounds the contact and a rubber boot seal snaps over the flange. Located within the rubber boot is a conductive rubber pin which contacts with a conductor located in the barrel of the gun. Utilization of this design minimizes capacitance in the front end of the gun and also virtually eliminates air volume in the area which in turn limits the production of harmful ozone.
A method of selecting the optimum value for a series limiting resistor in conjunction with a high-voltage power supply of the Cockcroft-Walton type, wherein the high-voltage circuit is used to deliver an electrostatic field in a volatile atmosphere of the type associated with paint spraying systems.
