| 摘要 |
A spray gun for electrostatic powder coating, for example having electrodes connected to a high voltage source, and having a combination, constructed as a jet pump (a so-called injector) of a blowing nozzle and a Venturi nozzle. Viewed in the direction of flow of the powder/gas mixture flowing through the gun, the Venturi nozzle is downstream of the blowing nozzle and upstream of the exit orifice, the distance between the orifice of the blowing nozzle and the narrowest part of the Venturi nozzle being between 2 and 20 mm, whilst the distance between the Venturi nozzle and the exit orifice is 30-300 mm. In order that the powder which leaves the Venturi nozzle and flows in a finely divided form in the gas stream shall not be braked (slowed down) excessively by contact with the wall, the Venturi nozzle can be followed, at a distance of 10-100 mm, by an annular nozzle for introducing a further stream of gas, which surrounds the powder/gas stream. To achieve certain shapes of exit jet, the exit orifice can be continuously flared up to its end; further, its end can be provided with a further annular nozzle, a corresponding ring of individual nozzles or the like, from which a further additional gas stream exits in the pattern of a cone or fan.
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