A generator is provided inside equipment, such as a sprayer, having a high voltage cascade including a voltage-gain transformer and a voltage multiplier arranged at the output of the transformer. The transformer is a double or multiple transformer, including at least two elementary transformers, whereof respective primary windings are mounted electrically in parallel, and whereof respective secondary windings are mounted electrically in series, the arrangement reducing a diameter of the cascade to facilitate incorporation in the sprayer or other equipment. The invention is applicable to painting robots for the automotive industry.

Electrostatic spray appliance for coating material for the spray-coating of articles comprises a single carrier (4) which carries a plurality of gun barrels (6, 8), so that the carrier (4), together with the gun barrels, forms spray guns. The gun barrels (6, 8) are releasably fastened to the carrier (4). The supply lines (54, 56, 58, 60, 62, 64, 78) are combined to form a line bundle and are led through a movable robot arm (68) in the longitudinal direction of the arm on the side of the carrier (4) facing away from the gun barrels (6, 8). The spray nozzles (12) are preferably slit nozzles having slits arranged obliquely relative to their theoretical connecting line.

A corona charge spray gun for dispensing powders for powder coatings. The spray gun includes a housing defining a chamber terminating in an outlet passageway. A high voltage electrode is mounted in the chamber spaced upstream of the outlet passageway and a ground electrode is mounted in the chamber spaced upstream from the high voltage electrode. The ground electrode is selected to have a surface area sufficiently larger than the surface area of the high voltage electrode in order to allow high voltages to be applied to the high voltage electrode without arch discharging occurring in the chamber. An inlet opens into the chamber for conducting a powder-gas mixture into the chamber and the electrodes receive cleaning gases for avoiding powder deposits on the electrodes.

An electrostatic spray gun apparatus includes a spray gun housing and a nozzle attached to a spray end of the housing, and a powder path that extends in a substantially straight line along an axis of the housing from the powder inlet to the powder outlet. The powder path is in the form of an enclosed smooth powder passage that is substantially continuous and uninterrupted from the powder inlet to the powder outlet to eliminate substantially all recesses or gaps that could capture or trap powder. The powder passage is formed by a plurality of tubular segments that are aligned along the housing axis and abut end to end. that when assembled in the housing axially compress the segments together to substantially eliminate dead spots or recesses to form the continuous smooth powder path. A gun purge function is provided that allows a purge line to be installed on the gun assembly. A cartridge valve and conductor assembly is provided between the gun electrode in the nozzle and the output of the voltage multiplier. The cartridge includes a conductive path to provide electrical continuity from the multiplier to the gun electrode, and also includes valve, preferably in the form of a stem check valve, that closes when the gun electrode is removed or at least unseated from the nozzle. The gun also includes a tube mount arrangement wherein the tube mount is rigidly held together with the gun housing in axial compression by a tie bar.

A high-voltage powder spray gun includes a rear terminal segment (60) of a powder tube (38) and the front terminal segment (58) of a hookup tube (56) which are inserted far enough in axial and sealing manner to subtend, between their overlap ends (69, 78), a powder-tight, electrically insulating expanse (76) to preclude electrical leakage currents. An electrically conducting bush (42) runs over the outer overlap end (78) of the hookup-tube/powder-tube connection to shunt any electric charges that might issue at the outer overlap end (78) between the hookup tube (56) and the powder tube (38). An electrically grounded shielding sheath (90), such as a helical compression spring, is configured radially away above the outer overlap end (88) between the rear terminal segment of the hookup tube (56) and the front end of powder hose (84) slipped over the rear terminal segment. This configuration prevents arcing on the hand of an operator in the event electric charges were to issue between the powder hose (84) and the hookup tube (56).