A fluid stud and resistor design for electrostatic spray guns has a fluid passage which is shaped like a cloverleaf in cross section. By providing this cross-sectional shape, the resistor is allowed to reside in one wall of the fluid stud and run, nearly, the complete length of the stud, thereby providing an increased effective resistor length, thus reducing flash-over and providing a smaller contact wire, thereby reducing capacitance. The design of the fluid needle and electrode is provided so as to reduce the length of the electrode wire, thereby reducing capacitance and allowing an increased diameter wire for increased durability.
A continuous electrical connection between a high voltage power source and a paint charging electrode in an electrostatic spray gun. The electrode is mounted on a valve needle which is reciprocated by a trigger mechanism as the spray gun is operated. A novel spring establishes and maintains the electrical connection from a stationary contact on the gun barrel to the moving valve needle. The spring may be mounted on a spacer tube mounted coaxially about the valve needle. The spacer tube can move in an axial direction to exert a force on a seal between the barrel and the valve needle without affecting the electrical connection.
An expansion device for refrigeration system having a piston which reciprocates to either open or close ports to increase or decrease the volume of atomized refrigerant liquid received from the condenser. Atomization may be enhanced by use of auxiliary ultrasonic or electrostatic atomization devices.
A spray gun is provided with an angled spray head for use on painting robots. The spray head is designed for attachment to a conventional spray gun and utilizes an angled retaining ring in conjunction with a conventional retaining ring, a conventional spray cap, and angled fluid nozzle. This arrangement allows rotation and orientation of the pattern at various angles relative to the body of the robot as desired by the operator. The electrode needle is formed of flexible material so as to enable it to flex through the angled fluid passage.
The rotary atomizer coater is particularly adaptable to a high voltage rotary atomizer coater which can be robot mounted. A rotatable bell cup, which is mounted on a turbine driven shaft is positioned within a housing. A fluid tube within the housing includes a fluid discharge tip which extends through an inlet opening in the bell cup for supplying charged coating fluid directly to the inner surface of the bell cup interior which is open to atmosphere. An electrical resistor is mounted between the fluid discharge tip and a power supply within the housing. When a grounded object approaches the bell cup, the current between the bell cup and the grounded object will increase and voltage drop across the resistor results, thereby reducing the voltage at the bell cup and diminishing the potential for a high energy spark.
Induction charging apparatus for HVLP spray guns includes an air cap having a central fluid exit orifice for receiving the spray gun nozzle. The cap includes one or more charging electrodes surrounding the orifice and carrying a voltage sufficiently large to induce on the spray droplets charges of a polarity opposite to that on the electrodes. The cap includes a rotatable electrical connector to enable the cap to rotate 360.degree., while maintaining electrical connections between the electrodes and a power supply.
