Swift Valve

The Swift valve is a sonic flow-metering valve. The valve has a

converging/diverging nozzle and a moving needle to adjust the valve flow area.

An open loop step motor through a rack and pinion drive positions the needle. A

return spring is included to remove the effects of gear backlash and to minimize

closed-valve leakage. A mechanical stop allows the valve to re-zero the valve

position during start-up. After the re-zero, the driver counts the step motor steps

and monitors the step motor position.

Swift Driver

The driver is effectively a positioner that will accept a desired position signal from

another device in the system, such as a speed control, and drive the valve to that

position. The position controller software is executed on dual Texas Instruments

16-bit DSPs, operating at 40 MHz, onboard the Swift Driver. The driver can be

commanded to a position via 4–20 mA, PWM, or CAN/DeviceNet interfaces. The

driver monitors all available signals, internal and external, and annunciates any

detected shutdown conditions through the discrete output. A discrete input is

available to remotely shut down the actuator and to reset shutdown conditions.

Features of the driver include dual (2) model-based position control loops, on-line

diagnostics, CAN communications, and service port communications (described

in detail in Chapter 5). A Windows-based Service Tool software program is

available for monitoring, troubleshooting, and parameter adjustments. The

Service Tool software is loaded on a PC and communicates serially to the driver

via RS-232. Refer to Chapter 7 (Service Tool) for installation instructions.