Curtis Dyna-Fog 2742, Руководство пользователя

Страница: 39 / 84

ELECTRICAL CONTROL
NOTE: The electrical controls do not require periodic maintenance but should be checked when
the machine does not function properly. The electric controls consist of the switches, solenoid,
read-out system, optical tachometer, valve and gear pump. Normal operation of the basic
components is described below:
1. FORMULATION ON/OFF VALVE: The electronically operated ON/OFF valve is controlled
by the switch on the remote control panel labeled OUTPUT-ON and an interlock circuit
located on the RATE CONTROL printed circuit board. The solenoid valve should be open
any time the OUTPUT-ON switch is in the ON position unless the pump is in a loss of
control, over speed, or open loop condition. In the latter condition, the indicator light on the
control panel marked FAULT will be illuminated.
2. ROTARY GEAR PUMP: The rate of flow of formulation is dictated by the rate of rotation of
the gear pump. For each revolution of the gear pump a fixed amount of fluid is metered into
the nozzle system. The fluid variation at a given speed is essentially independent of the
viscosity or temperature of the fluid. Gear pump is magnetically coupled to the drive motor
such that there is no rotary seal within the pump. The Formulation Control System consist of
an electrically operated spray-flush valve, and electrically operated ON/OFF valve, a positive
displacement rotary gear pump, and an electrical rate control and read-out system.
FMI PUMPING SYSTEM: Pumping the liquid is accomplished by the piston rotating and
moving in and out of the piston cylinder, all at the same time. The pump is driven by a 12
VDC electric motor. For each revolution of the pump a fixed amount of liquid is accurately
metered into the nozzle system. The pump is virtually unaffected by liquid viscosity and
temperature. The piston is made of ceramic and the cylinder is stainless steel with a
chemically inert carbon liner. Clearance between the cylinder and piston are in the
millionths of an inch range. Viton wiper seals prevent any liquid from leaving the cylinder.
The FMI pumping system can be supplied with the optional Synchroflow automatic-flow-
control system.
DIAPHRAGM PUMPING SYSTEM: Pumping the liquid is accomplished by an electric motor
driving an eccentric cam. The cam actuates a diaphragm that moves liquid as the motor
rotates. The motor operates at a fixed speed. Liquid flow is varied by using a needle type
metering valve on the pump discharge side. Liquid that is not fed to the nozzle system is
by-passed back to the inlet side of the pump.
3. SPRAY-FLUSH VALVE: The Spray-Flush is a 3-way solenoid valve capable of connecting
the input to the pump from the formulation tank or alternately from the flush solution tank.
4. RATE CONTROL SYSTEM: The electrical rate control system consist of a command
potentiometer, a pulse width modulated motor driver, the motor portion of the motor gear-
pump, an optical tachometer generator, and an optical tachometer decode circuit.
5. OPTICAL TACHOMETER:
The optical tachometer is used on the Gear and FMI
Pumping systems. It operates on the principle of interruption of the transmission of
infrared light from a light emitting diode to a photo transistor. A 40 tooth narrow
faced spur tooth gear is used as the interrupting device. As the gear turns through
the sensor the transmission is interrupted 40 times per complete revolution of the
rate 40 pulses per second. At 25 revolutions per second the pulse rate is 1000
pulses per seconds. These pulses are fed into a frequency to voltage converter
which generates a DC voltage analogous to flow rate. This voltage is attenuated and
scaled to give a read-out in ounces/minute or milliliters/minute.
39