Category: Woodward

We are a global leader in custom oil flow and temperature control devices

for direct drive and geared engine architectures. We provide aircraft turbine

system performance enhancements via custom flow modulation,

which includes flight critical applications in oil modulation, controlled bearing

cooling flow, thermal management, heat exchanger bypass and your specific valves.

Features & Benefits Highlights

• Leading fuel, oil, actuation, air, and combustion systems

• Innovative systems approach to integrate fight critical, customized functionality while minimizing piece

parts

• Highly reliable and cost-effective solutions delivered within severely condensed program schedules

• High reliability and lower risk with technology based on millions of flight hours

Hydraulic Filter Assembly

The valve is supplied with an integrated, high-capacity filter. The broad range filter protects the internal

hydraulic control components from large oil-borne contaminants that might cause the hydraulic

components to stick or operate erratically. The filter is supplied with a visual indicator which shows when

the recommended pressure differential has been exceeded and thus replacement of the element is

necessary.

LVDT Position Feedback Sensors

The SonicFlo control valves use a dual-coil, dual-rod LVDT for position feedback. The LVDT is factory set

to give 0.7 Vrms feedback at minimum position and 3.5 Vrms feedback at maximum position, when

supplied with 7 Vrms excitation at 3000 Hz.

Trip Relay Valve Assembly

The SonicFlo™ valve uses a solenoid-operated trip relay circuit to operate a high capacity, three-way,

two-position, hydraulically operated valve. This trip relay circuit consists of four functional elements: the

trip relay solenoid valve, the trip relay supply orifice, the hydraulically operated trip valve, and the trip

relay volume.

In the normal run mode, the trip relay solenoid valve is closed, which prevents the trip relay volume from

bleeding to the hydraulic return. As a result, high-pressure oil is fed into the trip relay circuit through the

supply orifice, which quickly pressurizes the trip circuit to supply pressure. When the trip circuit pressure

increases above 1100 kPa (160 psig), the three-way relay valve shifts position so that the common port

connects the control port of the servo-valve to the lower piston cavity of the actuator, allowing the servo

valve to position the throttle valve.

The solenoid valve opens when it is de-energized. Opening the solenoid valve causes the trip circuit to be

connected to drain. This in turn causes the three-way relay valve to shift position so that the common port

is connected to the hydraulic drain circuit, and isolated from the hydraulic supply. As the pressure falls

within the lower piston cavity, the return spring rapidly returns the valve plug to the downward position,

closing the control valve and shutting off fuel to the engine.

Triple Coil Electrohydraulic Servo Valve Assembly

The hydraulic actuator assembly uses a two-stage hydraulic servo valve to modulate the position of the

actuator output shaft and thereby control the gas fuel valves. The first stage torque motor utilizes a triple

wound coil, which controls the position of the first and second stage valves in proportion to the total

electric current applied to the three coils.

If the control system requires a rapid movement of the valve to send more fuel to the turbine, total

current is increased well above the null current. In such a condition, control port PC1 is connected to

supply pressure. The flow rate delivered to the piston cavity of the actuator is proportional to the total

current applied to the three coils. Thus, the opening velocity is also proportional to the current (above

null) supplied to the torque motor.

If the control system requires a rapid movement to close the gas fuel valve, the total current is reduced

well below the null current. In such a condition, port PC1 is connected to the hydraulic drain circuit. The

flow rate from the piston cavity to drain is proportional to the magnitude of the total current below the

null value. Thus, the closing velocity is also proportional to the current (below null) supplied to the torque

motor.

Introduction

The SonicFlo™ valve controls the flow of gas fuel to the combustion system of an industrial or utility gas

turbine. The unique design yields a linear flow characteristic unaffected by discharge pressure up to a

pressure ratio (P2/P1) of at least 0.8. The design also integrates the valve and actuator into a compact

assembly. The key characteristics of this valve are a highly linear critical gas flow versus stroke

relationship at constant upstream pressure. The integral actuator is a single-acting spring-loaded design

for failsafe operation. The actuator includes an onboard hydraulic filter for last chance filtration of the

fluid to ensure reliability of the servo valve and actuator. The servo valve is electrically redundant with

triple coil design. Feedback for the actuator is provided by a dual coil, dual rod LVDT (linear variable

differential transformer) directly coupled to the hydraulic piston.

Near the null current, the four-landed valve isolates the control port from the hydraulic supply and drain,

balancing the piston pressure against the spring to maintain a constant position. The control system,

which regulates the amount of current delivered to the coils, modulates the current supplied to the coil to

obtain proper closed loop position of the valve.

Applications

SonicFlo™ gas valves provide precise fuel control and shut-off capabilities for large

industrial gas turbines with single or multiple combustion manifold systems. 

The designs feature closely integrated linear valves and actuators which are

based on Woodward’s extensive experience with gas fuel controls.

Robust design and component redundancy result in exceptional service life and system

reliability. The assemblies may be used with electronic controllers

to achieve state-of-the-art control accuracy and response characteristics.

The integral actuator is a single-acting spring-loaded design for failsafe operation.

The actuator includes an on-board hydraulic filter for last-chance filtration of the fluid

to ensure reliability of the servovalve and actuator. The servovalve is electrically

redundant with triple coil design. Position feedback for the actuator is provided by

either a dual or triple coil LVDT (linear variable differential transformer) directly

coupled to the hydraulic piston. Rapid or emergency failsafe operation of the valve

may be initiated by use of the solenoid-operated trip system. The trip system

bypasses the servovalve-modulating control and directs the actuator to its failsafe

position.

The SonicFlo valve controls the flow of gas fuel to the combustion system of an

industrial or utility gas turbine. The unique design yields a flow characteristic

unaffected by discharge pressure up to a pressure ratio (P2/P1) of at least 0.80 for

Standard Recovery and at least 0.91 for High Recovery, reducing the requirement

for additional gas pressure boosting. The design integrates the valve and actuator

into a compact assembly. This close integration allows for lower costs, smaller

envelope and better accuracy.

The integral actuator is a single-acting spring-loaded design for failsafe operation.

The actuator includes an on-board hydraulic filter for last-chance filtration of the fluid

to ensure reliability of the servovalve and actuator. The servovalve is electrically

redundant with triple coil design. Position feedback for the actuator is provided by

either a dual or triple coil LVDT (linear variable differential transformer) directly

coupled to the hydraulic piston. Rapid or emergency failsafe operation of the valve

may be initiated by use of the solenoid-operated trip system. The trip system

bypasses the servovalve-modulating control and directs the actuator to its failsafe

position.

RS-232 Communications Port

An RS-232 communications service port is provided in the J1 harness plug for

connection to a PC service tool. This connection is a typical three-wire RS-232

communication (Tx = J1-A1. Rx = J1-A2. Gnd = J1-A3), which is limited to 15 m

(50 feet). The port supports OPC protocol and has fixed communications settings

of 38.42 K baud rate, 8 data bits, no parity, and 1 stop bit. Refer to Chapter 7 for

details on the Service Tool.

CAN Communications Port

The driver has CAN communications, version 2.0B, with 29-bit identifiers. The

CAN port supports independent positioning (position demand from CAN) and

shutdown of each driver channel. It also supports driver diagnostic monitoring

and position demand feedback. Reading of CAN parameters is available

regardless of the configured Demand Source. The address and data rate

parameters are set using the Service Tool. The data rate may be chosen from

125 kbps, 250 kbps, and 500 kbps.

Shutdown/Reset Discrete Input

When the shutdown contact is opened, the driver goes into a shutdown mode

and the valves are commanded to and held at minimum position. When the

shutdown contact is closed, the driver returns to ‘run’ mode and it resets all driver

faults.

Discrete Output for Driver Status Indication

The discrete output contact is normally on/closed (customer-supplied power

applied to load such as a trip-string relay) under normal driver operation, and

turns off/opens to indicate any detected shutdown condition within the driver.

Both alarm and shutdown indications are latching, which means a reset

command is required to clear the fault. The Service Tool program can be used to

interrogate the cause of the alarm or shutdown. The CAN communications can

also be used to determine alarm and shutdown causes.

The Swift Gas Metering System will continue to operate with an alarm condition

(for example, failure of the primary demand signal). However, the unit will cease

to operate on a shutdown condition (for example, failure of position demand input

signal).

Power Input

The input power has an operational range of 21.5—28 Vdc, nominal 24 Vdc.

Input power out-of-range diagnostics are provided.

Analog Input for Position Demand

The analog inputs are nominally 4–20 mA (25 mA range). Range and failure

diagnostics are provided based on software configuration and settings.

PWM Input for Position Demand

The PWM input accepts a 500 to 2000 Hz input signal of 5 to 26 volts peak-to

peak voltage (referenced to unit battery ground), and each channel is

independently jumper-configurable to accept push-pull or open-collector PWM

signals. The PWM input duty cycle minimum and maximum fields are adjustable

to match the controller sending the demand. Range and failure diagnostics are

provided based on software configuration and settings.