Device for rotating a fluid inside a spray nozzle, assembly comprising such a device and coating device

A spray gun for a liquid coating product, comprising:

• a spray nozzle disposed around a spray axis of the spray gun, the spray nozzle defining a liquid passage conduit for the liquid coating product to be discharged, the liquid coating product circulating through the liquid passage conduit;
• a needle valve, translatable inside the spray nozzle for selectively closing off the liquid passage conduit of the spray nozzle;
• a device for rotating the liquid coating product inside the spray nozzle, as the liquid coating product circulates through the liquid passage conduit, this device:
• being a separate part from the needle valve,
• being received inside the liquid passage conduit,
• being secured to the spray nozzle so as to be entirely immobile in the liquid passage conduit,
• defining a central through bore for the passage of the needle valve, and
• comprising a body, immobile in the liquid passage conduit, defining at least one helical slot for the passage of all or part of the liquid coating product, the spray gun being configured so that the liquid coating product circulates in said at least one helical slot, so that said at least one helical slot causes the liquid coating product to circulate in a helical direction around the spray axis of the spray gun;
• and
• a spray head defining two compressed air discharge orifices extending at least partially through the spray head and configured to guide air jets towards the spray axis so that said air jets strike a jet of liquid coating product discharged through the spray nozzle to form a spray;
• wherein the spray nozzle is arranged coaxially with the spray head and at least partially inside the spray head.