LCS Air/Fuel Ratio Control for Emissions

Installation and Operation Manual
LCS Air/Fuel Ratio Control for EmissionsControlled Stationary Gas Engines
Manual 26151 (Revision C)
WARNING—DANGER OF DEATH OR PERSONAL INJURY
WARNING—FOLLOW INSTRUCTIONS
Read this entire manual and all other publications pertaining to the work to be performed
before installing, operating, or servicing this equipment. Practice all plant and safety
instructions and precautions. Failure to follow instructions can cause personal injury and/or
property damage.
WARNING—OUT-OF-DATE PUBLICATION
This publication may have been revised or updated since this copy was produced. To verify
that you have the latest revision, be sure to check the Woodward website:
www.woodward.com/pubs/current.pdf
The revision level is shown at the bottom of the front cover after the publication number. The
latest version of most publications is available at:
www.woodward.com/publications
If your publication is not there, please contact your customer service representative to get
the latest copy.
WARNING—OVERSPEED PROTECTION
The engine, turbine, or other type of prime mover should be equipped with an overspeed
shutdown device to protect against runaway or damage to the prime mover with possible
personal injury, loss of life, or property damage.
The overspeed shutdown device must be totally independent of the prime mover control
system. An overtemperature or overpressure shutdown device may also be needed for
safety, as appropriate.
WARNING—PROPER USE
Any unauthorized modifications to or use of this equipment outside its specified
mechanical, electrical, or other operating limits may cause personal injury and/or property
damage, including damage to the equipment. Any such unauthorized modifications: (i)
constitute "misuse" and/or "negligence" within the meaning of the product warranty
thereby excluding warranty coverage for any resulting damage, and (ii) invalidate product
certifications or listings.
CAUTION—POSSIBLE DAMAGE TO EQUIPMENT OR PROPERTY
CAUTION—BATTERY CHARGING
To prevent damage to a control system that uses an alternator or battery-charging device, make
sure the charging device is turned off before disconnecting the battery from the system.
CAUTION—ELECTROSTATIC DISCHARGE
Electronic controls contain static-sensitive parts. Observe the following precautions to
prevent damage to these parts.
•
Discharge body static before handling the control (with power to the control turned off,
contact a grounded surface and maintain contact while handling the control).
•
Avoid all plastic, vinyl, and Styrofoam (except antistatic versions) around printed circuit
boards.
•
Do not touch the components or conductors on a printed circuit board with your hands
or with conductive devices.
•
IMPORTANT DEFINITIONS
A WARNING indicates a potentially hazardous situation which, if not avoided, could result in
•
A CAUTION indicates a potentially hazardous situation which, if not avoided, could result in
•
A NOTE provides other helpful information that does not fall under the warning or caution
death or serious injury.
damage to equipment or property.
categories.
Revisions—Text changes are indicated by a black line alongside the text.
Woodward Governor Company reserves the right to update any portion of this publication at any time. Information
provided by Woodward Governor Company is believed to be correct and reliable. However, no responsibility is
assumed by Woodward Governor Company unless otherwise expressly undertaken.
© Woodward 2001
All Rights Reserved
Manual 26151
LCS A/F Ratio Control
Contents
DEFINITIONS OF TERMS AND ABBREVIATIONS .............................................. II
ELECTROSTATIC DISCHARGE AWARENESS ..................................................III
CHAPTER 1. GENERAL INFORMATION ........................................................... 1
Introduction.............................................................................................................1
LCS A/F Ratio System Features ............................................................................1
Specifications .........................................................................................................1
LCS A/F Ratio Control Parts List............................................................................1
CHAPTER 2. SYSTEM DESCRIPTION ............................................................. 2
Air/ Fuel Ratio Control Basics ................................................................................2
LCS A/F Overview of Operation .............................................................................3
CHAPTER 3. INSTALLATION.......................................................................... 6
Installation Tasks....................................................................................................7
Unpacking...............................................................................................................8
Mechanical Installation ...........................................................................................8
Electrical Installation—Power Requirements .......................................................13
CHAPTER 4. CALIBRATION AND EMISSIONS TUNING ................................... 14
CHAPTER 5. MAINTENANCE, FAULT INDICATIONS, AND OPERATION ............ 16
Introduction...........................................................................................................16
Maintenance .........................................................................................................16
Replacement Information .....................................................................................16
Operation..............................................................................................................17
CHAPTER 6. TROUBLESHOOTING ............................................................... 20
Suggested Troubleshooting Procedures..............................................................20
CHAPTER 7. SERVICE OPTIONS ................................................................. 21
Product Service Options.......................................................................................21
Returning Equipment for Repair...........................................................................22
Replacement Parts ...............................................................................................23
How to Contact Woodward...................................................................................23
Engineering Services ...........................................................................................24
Technical Assistance............................................................................................25
Woodward
i
LCS A/F Ratio Control
Manual 26151
Illustrations and Tables
Figure 2-1. Pre-Catalyst Emissions........................................................................2
Figure 2-2. Post-Catalyst Emissions ......................................................................2
Figure 2-3. LCS A/F Expected HEGO Sensor Response ......................................3
Figure 3-1. System Diagram...................................................................................6
Figure 3-2. Control Box Outline Drawing................................................................9
Figure 3-3. Mounting Hole Dimensions ................................................................10
Figure 3-4. Cover Removed for Mounting Hole Access.......................................10
Figure 3-5. Fuel Trim Valve Outline Dimensions .................................................11
Figure 3-6. LCS A/F Ratio Control Wiring ............................................................13
WARNING—FIX EXISTING PROBLEMS
The LCS Air/fuel Ratio Control is designed to supplement existing fuel
controls in order to automatically provide the optimum fuel mixture for
emissions compliance. As described in this manual, the system can be
helpful for engine tuning and diagnosis; however, the LCS control is not a
fix for an existing malfunction. The original engine, including the mechanical
components, air throttle(s), carburetor(s), governor, ignition system, and
safety shutdowns must be in proper working order before the LCS control is
put into operation.
Definitions of Terms and Abbreviations
A/F
catalyst
closed loop
CO
duty cycle
ECU
HC
HEGO
LED
NOx
open loop
PC
rpm
stoichiometric
ii
air fuel ratio control
also known as catalytic converter, a flow-through chemical
reactor mounted in the exhaust stream to decrease harmful
emissions; three-way refers to the simultaneous oxidation of
carbon monoxide (CO) and hydrocarbon (HC) along with
reduction of oxides of nitrogen (NOx) at fuel mixtures close to
stoichiometry.
control using feedback signals from the controlled parameter
carbon monoxide (emissions)
percent of on time per total on/off cycle time
electronic control unit
hydrocarbons (emissions)
heated exhaust gas oxygen sensor
light emitting diode
oxides of nitrogen (emissions)
control without feedback from any controlled parameters
personal computer
revolutions per minute
chemically balanced mixtures (all reactants mutually
consumed)—in the case of engine air/fuel mixtures, just
enough air to theoretically burn all the fuel
Woodward
Manual 26151
LCS A/F Ratio Control
Electrostatic Discharge Awareness
All electronic equipment is static-sensitive, some components more than others.
To protect these components from static damage, you must take special
precautions to minimize or eliminate electrostatic discharges.
Follow these precautions when working with or near the control.
1.
Before doing maintenance on the electronic control, discharge the static
electricity on your body to ground by touching and holding a grounded metal
object (pipes, cabinets, equipment, etc.).
2.
Avoid the build-up of static electricity on your body by not wearing clothing
made of synthetic materials. Wear cotton or cotton-blend materials as much
as possible because these do not store static electric charges as much as
synthetics.
3.
Keep plastic, vinyl, and Styrofoam materials (such as plastic or Styrofoam
cups, cup holders, cigarette packages, cellophane wrappers, vinyl books or
folders, plastic bottles, and plastic ash trays) away from the control, the
modules, and the work area as much as possible.
4.
Do not remove the printed circuit board (PCB) from the control cabinet
unless absolutely necessary. If you must remove the PCB from the control
cabinet, follow these precautions:
•
Do not touch any part of the PCB except the edges.
•
Do not touch the electrical conductors, the connectors, or the
components with conductive devices or with your hands.
•
When replacing a PCB, keep the new PCB in the plastic antistatic
protective bag it comes in until you are ready to install it. Immediately
after removing the old PCB from the control cabinet, place it in the
antistatic protective bag.
CAUTION—ELECTROSTATIC DISCHARGE
To prevent damage to electronic components caused by improper handling,
read and observe the precautions in Woodward manual 82715, Guide for
Handling and Protection of Electronic Controls, Printed Circuit Boards, and
Modules.
Woodward
iii
LCS A/F Ratio Control
iv
Manual 26151
Woodward
Manual 26151
LCS A/F Ratio Control
Chapter 1.
General Information
Introduction
This manual describes the LCS Air/Fuel (A/F) Ratio Control system for use with
carbureted, gaseous-fueled engines. This control kit can be applied on engines
between 100 and 250 kW (134 and 340 hp). The LCS A/F Ratio Control provides
precise air/fuel ratio control for engines using three-way catalytic converters to
reduce exhaust emissions (stoichiometric or rich-burn engines).
LCS A/F Ratio System Features
•
•
Microprocessor-based
9–16 Vdc supply operation voltage (must be fed from a Class 2 power
source)
Pre-catalyst, closed loop, exhaust oxygen feedback control
LED graphic display of oxygen sensor response
Manual switch for open-loop operation
Adjustable default valve position and control response (gain)
Diagnostics for min and max valve positions and oxygen sensor failure
LED diagnostic indicators
UL/cUL listed (requires a Class 2 power source or isolated source)
•
•
•
•
•
•
•
Specifications
Power Supply:
Power Consumption:
Ambient Operating Temperature:
Storage Temperature:
Shock/Vibration:
EMC Standards
12 volt system, 9 to 16 Vdc (must be fed
from a Class 2 power source)
100 W max, 25 W nominal,
15 A fuse recommended
–20 to +70 °C (–4 to +158 °F)
–40 to +125 °C (–40 to +257 °F)
US MIL-STD 810E
EN61000-6-2 and EN50081-2
LCS A/F Ratio Control Parts List
•
•
•
•
•
•
•
•
Woodward
Part Number 8301-629 (kit)
LCS A/F Control Box
LCS A/F Control Valve
Cable—LCS (1.5 m/5 ft length standard, 4.6 m/15 ft shielded optional—part
number 5417-699)
Cable—HEGO (1.5 m/5 ft length standard, 4.6 m/15 ft shielded optional—
part number 5417-701)
HEGO Sensor—Bosch 0 258 005 703 009 (or 15703)
Weld Fitting for HEGO sensor—18 mm
Operation and Installation Manual
1
LCS A/F Ratio Control
Manual 26151
Chapter 2.
System Description
Air/ Fuel Ratio Control Basics
The LCS A/F control is a microprocessor-based air/fuel ratio controller for fourstroke, gaseous-fueled engines operating with a near-stoichiometric air/fuel ratio.
It is designed to work in conjunction with a three-way catalytic converter to
efficiently reduce exhaust emissions. By automatically maintaining an optimum
air/fuel mixture, emissions compliance is achieved and catalyst life is maximized
without operator supervision.
A catalyst that simultaneously eliminates hydrocarbons (HC), carbon monoxide
(CO), and oxides of nitrogen (NOx) is referred to as a “three-way” catalyst. The
use of a three-way catalyst will reduce the emissions of a stoichiometric engine.
However, a very precisely controlled air/fuel ratio is required.
Typical curves are shown Figure 2-1 for pre-catalyst exhaust emissions. Within a
narrow window around stoichiometry, the emissions exiting the catalyst will be
reduced dramatically, as shown in Figure 2-2.
The heated exhaust gas oxygen sensor (HEGO sensor) will generate a voltage
signal that is characteristic of this ideal stoichiometric window. The HEGO sensor
operates as a reference-gas sensor, and compares the residual oxygen in the
exhaust gas with the oxygen in the reference atmosphere (air circulating inside
the sensor). The active sensor ceramic is heated by an internal heating element.
Sensor heating reduces the influence of the exhaust gas temperature on the
sensor-ceramic temperature and therefore the temperature-dependent sensor
functions. The LCS A/F control system monitors the system HEGO output and
adjusts the trim valve fuel flow for optimum emissions.
Figure 2-1. Pre-Catalyst Emissions
2
Figure 2-2. Post-Catalyst Emissions
Woodward
Manual 26151
LCS A/F Ratio Control
LCS A/F Overview of Operation
When power is first applied to the LCS A/F Ratio Control unit, the control is open
loop until the HEGO sensor warms up. When the sensor is up to temperature
and operating normally, the signal will fall to a typical 0–1V operating range. As
the sensor ages or is damaged (or if the sensor becomes disconnected), the
signal will be pulled up over this nominal range, which causes open-loop
operation. An adjustable default trim valve position is selected whenever the
control is in open-loop mode.
HEG O v olts
The HEGO sensor signal response to air/fuel ratio is highly non-linear, and this is
accounted for in the control response. The LCS A/F has a control curve that
compensates for the response of a particular HEGO sensor (Bosch 0 258 005
703 009 or 15703). The response of this sensor is depicted in Figure 2-3. The
accuracy of the HEGO voltage reading is critical for consistent emissions. If
another sensor is used with a different voltage response, the emissions output
may be erratic.
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30
Normalize d F/A ratio, phi
Figure 2-3. LCS A/F Expected HEGO Sensor Response
Stoichiometric operation is indicated by a normalized F/A ratio (phi) of 1. For
typical catalysts, especially when operating on natural gas, the control must be
set slightly rich. This corresponds to a HEGO sensor voltage output of about 0.7
to 0.8 V.
Woodward
3
LCS A/F Ratio Control
Manual 26151
Open Loop Control
There are three different conditions that will allow the control to operate openloop:
•
•
•
During initial start-up, the control is open-loop until the HEGO sensor warms
up.
Any time the HEGO sensor is disconnected or only provides a weak signal
from aging, the control is open-loop.
Open-loop operation can also be manually selected with the CONTROL
MODE (OPEN/CLOSE) switch on the control keypad.
Whenever the control is open-loop, the fuel trim valve will go to the default
position, which is programmable by the user.
Closed Loop Control
Once power is applied to the unit, the control will remain open-loop for 30
seconds or until the sensor is warmed up, whichever is longer. Once the O2
sensor warms up and is reading from 0 to 1 V, the LCS enters closed loop
control. In this mode, the control attempts to keep the O2 voltage at the setpoint
by moving the LCS valve. The user can program both the setpoint and the valve
response gain.
Customer Configurable Features
The operator may change the default position, the HEGO voltage set point, or
the control gain (response) using the RAISE and LOWER keypad switches:
1) Changing the default valve position/open loop operation:
When the LCS A/F control is operating open loop, the raise and lower switches
on the keypad change the default valve position, regardless of the state of the
ADJUST SELECT switch. The default position will move at a one-minute slew
rate (holding the RAISE or LOWER switch for at least one minute ensures the
valve is completely open or closed). Each time a raise/lower switch is pressed,
the default position changes by 0.23°. By watching the HEGO sensor voltage
LED display at a typical operating condition, the proper default position can be
chosen to keep the open-loop HEGO response near the closed-loop voltage
target. When the RAISE and LOWER switches are released (and after a delay of
approximately 30 seconds), the final value for the default position is saved as a
‘permanent’ tuning value. The default position value can also be immediately
saved by pressing the RAISE and LOWER switches at the same time.
4
Woodward
Manual 26151
LCS A/F Ratio Control
2) Changing the HEGO voltage set point/closed loop operation:
With the LCS operating closed-loop and the ADJUST SELECT switch on SETPT,
the RAISE and LOWER switches will change the HEGO voltage set point. The
HEGO voltage set point will move at a two-minute slew rate (holding the keypad
switch for two minutes will travel the entire range from 0.2 to 0.8 V, but the range
of realistic set points is between 0.65 to 0.85 V, which only takes 24 seconds).
Each time a raise/lower switch is pressed, the O2 voltage setpoint changes by
0.005 V. When the RAISE and LOWER switches are released (and after a delay
of approximately 30 seconds), the final value for the set point is saved as a
‘permanent’ tuning value. The set point value can also be immediately saved by
pressing the RAISE and LOWER switches at the same time.
3) Changing the control gain/closed loop operation:
With the LCS operating closed-loop and the ADJUST SELECT switch on GAIN,
the RAISE and LOWER switches will change the gain, or control response. The
gain will move at a one-minute slew rate (holding the keypad switch for one
minute will travel the entire range from 0.4% to 100% gain). Each time a
raise/lower switch is pressed, the gain changes by 0.4%. When the raise and
lower switches are released (and after a delay of approximately 30 seconds), the
final value for the CL gain is saved as a ‘permanent’ tuning value. The gain value
can also be immediately saved by pressing the RAISE and LOWER switches at
the same time.
4) Resetting setpoint, gain, and default position:
The LCS is built with factory settings for setpoint, gain, and default position. The
LCS can be reset to run with these values at any time during the life of the
product as described in the operation section of Chapter 5. These factory
settings are available in case the settings accidentally get changed, the unit is
moved to another engine, or any other time that the user wishes to “start over”
with tuning.
Diagnostics
The FAULT/OPEN warning light will come on anytime the control is open-loop
(caused by operator selection with the CONTROL MODE switch, the HEGO
signal being weak or disconnected, or during initial sensor warm-up).
The lights will flash from FAULT/OPEN to CLOSE when the control is closedloop but “pegged” with the valve fully open or closed.
The carburetor settings must be carefully chosen to allow the LCS A/F control to
cover the normal range of engine speed and load, along with variations in the
fuel quality, variation in the mechanical carburetor components, temperature
differences between the fuel and air, etc.
Woodward
5
LCS A/F Ratio Control
Manual 26151
Chapter 3.
Installation
Figure 3-1. System Diagram
6
Woodward
Manual 26151
LCS A/F Ratio Control
Installation Tasks
The LCS A/F Ratio Control system installer should be able to perform the
following tasks with a high level of quality and workmanship, with consideration
given to any applicable laws and regulations for the specific location.
•
•
•
•
•
•
•
Provide a suitable controller mounting location.
Drill and tap (or weld) the oxygen sensor port into the engine exhaust
system.
Provide low-pressure fuel pipe or hose fittings and valves for the fuel trim
valve. If necessary, fabricate strong, stiff mounting brackets with
consideration for vibration and fatigue.
Provide a switched ‘run’ signal for the controller (typically 9–16 Vdc from
start/ignition switch).
Provide a 15 A fuse installed in line with the main 9–16 Vdc power supply
(typically connected to battery) (must be fed from a Class 2 power source).
Provide a fuel source for the trim valve (usually teed from of the stock
carburetor fuel supply), 0.5 to 2.0 kPa (2 to 8 inches) water pressure.
Analyze exhaust emissions for calibration.
NOTE
If the installer is unfamiliar or unable to complete any of the installation
requirements listed above, contact your LCS A/F Ratio Control distributor
for information on qualified installers.
Included LCS A/F Ratio Control System Components (P/N 8301-629)
• LCS A/F Ratio control box with integral operator keypad and HEGO voltage
indicator
• LCS fuel trim valve
• HEGO sensor
• HEGO sensor port weld fitting
• LCS and HEGO cable assemblies, 1.5 m (5 ft) length
• LCS A/F Ratio Control manual
Optional LCS A/F Ratio Control System Components
• LCS shielded cable assembly, 4.6 m (15 ft) length (P/N 5417-699)
• HEGO shielded cable assembly, 4.6 m (15 ft) length (P/N 5417-701)
Required Installer-Provided Components
• 9–16 Vdc fused power supply and a switched ‘run’ signal (typically a fused
battery connection and a signal from the start/ignition switch), 100 W max, 25
W nominal, 15 A fuse recommended (must be fed from a Class 2 power
source).
• Oxygen sensor port (M18 x 1.5 internally threaded, gasket spot face or weld
fitting provided).
• Manual shut-off valve for the trim valve plumbing (1/2 inch [13 mm] NPT 1/4turn valve).
• Appropriate fuel plumbing from stock carburetor fuel source (0.5 to 2.0 kPa/2
to 8 inches water pressure) to the shut-off valve and trim valve and from the
valve to the injection point.
• Fittings for fuel source, fuel trim valve and injection point.
• Mounting brackets, if necessary, for the fuel metering valve and plumbing.
Woodward
7
LCS A/F Ratio Control
Manual 26151
Unpacking
Before handling the control, read Electrostatic Discharge Awareness on page iii.
Be careful when unpacking the electronic control. Check the control for signs of
damage such as bent panels, scratches, and loose or broken parts. If any
damage is found, immediately notify the shipper.
Mechanical Installation
Control Box/Operator Keypad
The control box can be attached to a panel with 4 screw-mounting holes, shown
in Figure 3-2 below, accessible under the front cover/keypad. Be careful when
removing the cover, as the keypad cable can be damaged if the cover is dropped
or suddenly pulled from the box. However, the cover can be completely removed
by gently unplugging the cable connector from the board. Follow the ESD
precautions on page iii.
Controller Location Considerations
• Access to and clearance for front cover/keypad
• Access for cables on bottom of unit
• Ventilation
• Space for adjustment and repair
• Protection from direct exposure to water or engine fluids
• Protection from high-voltage or high-current devices, or devices which
produce electromagnetic interference
• Avoidance of vibration; if the controller will experience direct engine vibration,
shock isolators are required
• Selection of a location that will provide an operating temperature range of
–40 to +70 °C (–40 to +158 °F)
8
Woodward
Manual 26151
LCS A/F Ratio Control
Figure 3-2. Control Box Outline Drawing
Woodward
9
LCS A/F Ratio Control
Manual 26151
Figure 3-3. Mounting Hole Dimensions
Figure 3-4. Cover Removed for Mounting Hole Access
10
Woodward
Manual 26151
LCS A/F Ratio Control
Fuel Trim Valve
Figure 3-5. Fuel Trim Valve Outline Dimensions
The trim valve assembly can be mounted in any orientation using four 5.40 mm
diameter through-holes in a 29 mm square pattern. M5 or #10 socket head
screws must be used. The back of the mounting flange is designed for use with
socket head cap screws only. These screw sizes will provide sufficient screw
head/casting clearance (standard hex head screws or hex head nuts should not
be used if seating against the mounting flange). The trim valve plumbing
connections are ½ inch – 14 NPT ports.
The diagram in Figure 3-1 shows the typical configuration for the LCS A/F Ratio
control system.
Plumbing Considerations
• The trim valve ports are sized for ½ inch (13 mm) NPT plumbing. Smaller
plumbing or restrictive fittings will reduce the control range of the system. A
nominal ½ to 9/16 inch (13 to 14 mm) ID throughout the plumbing is ideal.
• Low-pressure natural gas pipe or gas fuel hose is recommended.
• A manual shut-off valve must be installed between the fuel supply tee and
the valve for servicing and troubleshooting (1/4-turn ball valve).
• The plumbing should facilitate installation and servicing of the valve.
• The valve should be mounted as close to the injection point as possible; any
lengthy plumbing runs are more acceptable on the higher pressure, inlet side
of the valve.
• An automatic fuel shut-off valve for engine shutdown is required upstream of
the trim valve tee (a typical engine fuel supply will already have a fuel shutoff solenoid valve upstream from the final pressure regulator for the
carburetor).
• The injection point should be chosen to provide as much mixing as possible
before the intake splits to individual cylinders; just upstream from the existing
carburetor is ideal, but downstream may be acceptable if long intake
plumbing and/or elbows are present before the throttle. The injection point
cannot be after the throttle.
Woodward
11
LCS A/F Ratio Control
•
•
Manual 26151
Injection points where oil or fuel liquids pool up should be avoided, especially
if liquids drain to the metering valve.
All threads or hose fittings must be inspected for leaks with bubble-indicating
liquids or electronic flammable-gas detection equipment.
HEGO Sensor
Location of upstream HEGO sensor should be:
• In the combined exhaust stream from all the cylinders or after the
turbocharger if applicable.
• Within 60 cm (24 inches) of the exhaust manifold outlet or turbo outlet.
• On the top 180° of the exhaust pipe (to avoid corrosion and thermal shock
from condensation).
• Drill and spot face 15.5 mm hole in suitable location.
• Tap or weld internally threaded (M18 x 1.5) port around the hole (Woodward
#1138-581 included with kit).
• Install sensor with anti-seize thread lubricant and torque to 40 Nxm (30 lb-ft).
Oxygen Sensor Poisoning
Lubricants and sealants of any kind must be checked for oxygen sensor
compatibility—even for use on the intake or crankcase ventilation system.
Contaminants drawn into the engine can propagate through the combustion
process, and even small amounts can poison the activity of oxygen sensors.
Common sensor poisons include silicon, lead, and excessive oil contamination.
Gasket sealers (RTV silicone), pipe thread sealers (pipe dope), and solder or
brazing materials will typically contain these materials. Most products intended
for modern automotive use are sensor-safe, but many products common in
industrial environments are not. Double check products during repair or
maintenance, and when in doubt, use automotive products and procedures.
Excessive oil consumption by the engine will also affect oxygen sensor life—
regular maintenance of piston rings (and valve seals, where applicable) is very
important. Although the sensors are inexpensive, they are damaged by the same
contaminants that will eventually poison the exhaust catalyst. In other words, a
sensor failure may give warning that maintenance is needed before the catalyst
is also damaged.
12
Woodward
Manual 26151
LCS A/F Ratio Control
Electrical Installation—Power Requirements
The LCS A/F Ratio control system includes the electrical harnesses for the fuel
trim valve and the HEGO sensor. The only other electrical connections required
are a main battery connection to a voltage source of 9 to 16 Vdc (on the red
wire), a switched 9 to 16 Vdc ‘run’ signal (on the black wire), and power supply
ground (on the green wire). The controller draws a maximum of 100 W for the
controller, trim valve, and HEGO sensor heater. A 15 A fuse should be provided
in-line with the main controller battery connection. The switched ‘run’ signal will
only draw 40 mA maximum to energize the main power relay. All saved tuning
values will stay in memory on power supply failure. This must be fed from a
Class 2 power source.
+12V
GND
1
2
3
GRY
4
5
6
RAISE SWITCH
OXYGEN SENSOR GND
GAIN / SETPOINT MODIFICATION SELECT
4
5
6
7
8
LCS A/F RATIO
CONTROL BOX
3
9
10
7
OXYGEN SENSOR SIGNAL
OPEN / CLOSED LOOP LIGHT
LOWER SWITCH
8
9
10
11
11
12
12
1
Red Wire: Constant +12Vdc
Green Wire: System Ground
+
2
BLK
5
6
7
O2 Heater
A
B
C
D
-
O2 Sensor Gnd
O2 Sensor Signal
O2 Heater Gnd
4
O2
SENSOR
3
8
9
Black Wire: Switched +12Vdc
10
11
12
Figure 3-6. LCS A/F Ratio Control Wiring
Figure 3-6 shows the wiring for each connector in case any troubleshooting is
required.
CAUTION—INPUT VOLTAGE
To prevent damage to the control, do not exceed the input voltage range.
Make sure that the alternator or other battery-charging device is turned off
or disconnected before disconnecting the battery.
NOTE
If a battery is used for operating power, an alternator or other batterycharging device is necessary to maintain a stable supply voltage.
Woodward
13
BAT
2
LCS A/F RATIO
CONTROL VALVE
1
LCS A/F Ratio Control
Manual 26151
Chapter 4.
Calibration and Emissions Tuning
These instructions assume that the engine is in good operating condition and
that the mechanical carburetor has been properly installed and calibrated.
1. Close the manual shut-off valve on the fuel supply to the LCS A/F Ratio trim
valve.
2. Start the engine normally.
3. Verify that the indicator lights on the LCS A/F Ratio keypad are illuminated.
After about 30 seconds, the HEGO sensor should be warmed up and one of
the HEGO voltage lights should be on (somewhere on the ‘S’-shaped curve).
4. If the control is not already open-loop, manually select open-loop with the
CONTROL MODE switch on the keypad. The initial trim valve default setting
is about 10% open from the factory.
5. With the engine at about ½ load and rated speed, reduce the final pressure
regulator pressure until the HEGO voltage lights indicate a lean air/fuel ratio
(at the bottom of the curve).
6. With the engine still at about ½ load, slowly open the manual shut-off valve
on the fuel supply to the LCS A/F Ratio trim valve. Stop opening if the engine
stumbles or misfires. Continue reducing the final pressure regulator pressure
(and opening the manual valve to wide open) until the green HEGO voltage
lights in the center of the curve are on, if possible. It is ok if the regulator
pressure is as low as it will go without getting the HEGO voltage to the center
of the curve, just leave the regulator at its lowest setting and move on to the
next step.
7. Put 75% to 100% load on the engine at rated speed. Use the carburetor
main adjustment valve (power valve) to get the HEGO voltage in the center
of the curve. If the main adjustment valve on the carburetor is all the way
open or closed without getting the HEGO voltage to the center of the curve,
continue adjustments with the final pressure regulator as in the previous step
(but with high load still applied to the engine).
8. Run the engine at rated speed and no load. It may be necessary to close the
manual shut-off valve to keep the engine running stable. If the carburetor has
an idle adjustment screw, use it to move the HEGO voltage closer to the
center of the curve (while opening the manual shut off valve). If the idle
adjustment reaches a limit before the HEGO voltage is centered, continue
adjustments with the final pressure regulator as in the previous step (but with
no load applied to the engine). It may be necessary to find a compromise
setting with the final pressure regulator, but generally emissions are much
higher (and are only tested) under load, so the air/fuel ratio control at ½ load
and full load is a higher priority.
9. Manually select closed-loop operation with the CONTROL MODE switch on
the keypad. The LCS A/F Ratio fuel trim valve will now move to keep the
HEGO voltage in the center of the curve (on the green indicator lights).
14
Woodward
Manual 26151
LCS A/F Ratio Control
10. Verify that the LCS A/F Ratio control will keep the HEGO voltage in the
green range over all loads. If the FAULT/OPEN and CLOSE lights are
flashing and the HEGO voltage is low (lean), this indicates that the valve has
moved wide open without being able to reach the target voltage. Likewise, if
the FAULT/OPEN and CLOSE lights are flashing and the HEGO voltage is
high (rich), this indicates that the valve has completely closed without being
able to reach the target voltage. In either case, further adjustment with the
carburetor settings should be able to bring back closed-loop control and get
the fuel trim valve off of its’ limit. In general, the carburetor idle adjustment is
used at low loads (along with the final pressure regulator, if necessary), and
the carburetor main adjustment valve is used at high loads (along with the
final pressure regulator, if necessary).
11. If the HEGO voltage seems to be very unstable, swinging over the entire
range of green indicator lights (or more), the control gain should be
decreased by selecting GAIN with the ADJUST SELECT switch and pushing
the LOWER switch. A steady HEGO voltage indicator light or occasional
blinking between one light and the next one above or below is normal.
12. If the HEGO voltage is steady, but the voltage takes longer than 5 or 10
seconds to return to the green range after changing loads, the control gain
should be increased by selecting GAIN with the ADJUST SELECT switch
and pushing the RAISE switch. However, for low emissions, stable operation
at steady engine load is a higher priority than transient load response.
13. From the factory, the LCS A/F Ratio HEGO voltage set point (0.782 V)
should be close to the optimum target for good catalyst activity and low
emissions, but the final voltage target should be set with emissions analysis
equipment. While operating closed-loop, select SETPT with the ADJUST
SELECT switch and use the RAISE and LOWER switches to tune the
emissions. The best HEGO voltage set point for each application will depend
on the local emissions regulations. Most emissions equipment measures a
volume fraction of the emissions in the exhaust as ‘parts per million’, ppm.
However, most emissions regulations are based on mass units, such as
‘grams per horsepower-hour’, g/hphr. Finding the best set point is simple,
though, because air/fuel ratio tuning is primarily a trade-off between carbon
monoxide (CO) when operating rich, and oxides of nitrogen (NOx) when
operating lean. Since the molecular weights (or densities) of CO and NOx are
similar, tuning for the same proportion of CO and NOx in ppm units as the
proportion of CO and NOx in the g/hphr regulations will give good results. For
example, if the regulations call for 36g/hphr CO and 3g/hphr NOx, the best
tuning will give the same proportion in ppm, such as 3600 ppm CO and 300
ppm NOx or 1200 ppm CO and 100 ppm NOx. Since lowering CO causes
NOx to rise, and vice versa, it is best to tune for the proper proportion rather
than a specific value or the lowest possible value.
14. The final step is to set the default position for the valve in case the HEGO
sensor fails or is disconnected. At the most typical operating condition of the
engine, manually select open-loop operation with the CONTROL MODE
switch on the keypad. The default position can then be adjusted by pushing
the RAISE and LOWER switches until the HEGO voltage indication is similar
to the final set point from the previous step.
15. Verify that the engine will still start properly with this default position. Some
carburetors are very rich during engine starting, and any additional fuel from
the LCS A/F Ratio trim valve may cause difficult starting or rough idling until
the HEGO sensor warms up and the control goes closed-loop. In this case,
the best default position may be a compromise between open-loop operation
under load versus reliable starting.
Woodward
15
LCS A/F Ratio Control
Manual 26151
Chapter 5.
Maintenance, Fault Indications, and
Operation
Introduction
This chapter provides information for keeping the LCS A/F Ratio Control in
proper working order. Contact your Woodward distributor for service options.
WARNING—FIX EXISTING PROBLEMS
The LCS A/F Ratio Control is designed to supplement existing fuel controls
in order to automatically provide the optimum fuel mixture for emissions
compliance. As described in this manual, the system can be helpful for
engine tuning and diagnosis; however, the LCS A/F Ratio Control is not a fix
for an existing malfunction. The original engine, including the mechanical
components, air throttle, carburetor, governor, ignition system, and safety
shutdowns must be in proper working order before the LCS A/F Ratio
Control is put into operation.
Maintenance
The LCS A/F Ratio controller and system components were designed to be very
reliable in operation. No components require any maintenance, however the
heated exhaust gas oxygen sensor (HEGO sensor) has a limited life and will
require regular replacement.
A regular program for engine maintenance should continue after the LCS A/F
Ratio Control system is installed. To provide emissions compliance, the original
engine systems need to be in proper working order. Please review the warning
statement above, and any warnings associated with the HEGO sensor. The use
of certain gasket and thread sealers or high-temperature thread lubricants can
cause poisoning of the oxygen sensor. Excessive engine oil consumption can
also cause these effects over longer periods of time. The LCS A/F Ratio Control
system will relieve the operator of constant carburetor tuning for emissions
compliance, but consistent engine maintenance is still required.
Replacement Information
The highest maintenance requirement is for the automotive oxygen sensor
(HEGO sensor). The typical life expectancy for this component is on the order of
2000 to 4000 hours, or about three to six months of continuous service.
16
Woodward
Manual 26151
LCS A/F Ratio Control
Operation
FAULT/OPEN
LIGHT ILLUMINATED
If the FAULT/OPEN light is illuminated steadily, one of the following conditions is
true:
•
The user has manually selected open loop with the CONTROL MODE
button.
•
The O2 sensor is aged or damaged so that it is out of range.
•
The O2 sensor is warming up.
Wait one minute to ensure that the sensor is warm. If the OPEN/FAULT light
does not go off after this time, press CONTROL MODE to try to force the system
closed loop. If the CLOSE light still does not illuminate, replace the O2 sensor.
With this light illuminated, you can change the default position of the valve with
the raise / lower buttons. The default position should be adjusted so that optimal
emissions are maintained when the system is open loop (see Chapter 2, Closed
Loop Control).
Woodward
17
LCS A/F Ratio Control
Manual 26151
FAULT/OPEN & CLOSE LIGHTS FLASHING
If the unit is flashing from FAULT/OPEN to CLOSE, the valve is at one limit of its
travel, but it is still trying to go closed loop.
1. If the lights are flashing and lean lights are illuminated on the O2 trace, the
valve is fully open. The carburetor is adjusted too lean. Add more fuel with
the carburetor power screw adjustment.
2. If the lights are flashing and rich lights are showing on the O2 trace, the valve
is fully closed. If no light is illuminated on the O2 trace, the system is so rich
that it is off scale. Lean the carburetor.
If adjusting the carburetor does not help, the setpoint could have accidentally
been changed. Reset the unit to the factory defaults as outlined below and follow
the emissions tuning guidelines in chapter 4.
CLOSED LIGHT
ILLUMINATED
If the CLOSE light is illuminated steadily, the unit is in closed loop air fuel ratio
control. In this mode, the user can change the setpoint or gain as described in
Chapter 4.
18
Woodward
Manual 26151
LCS A/F Ratio Control
RESETTING FACTORY
DEFAULT SETTINGS
To reset the system to factory default settings:
•
Remove power to the unit.
•
Press and hold both RAISE and LOWER.
•
Apply power to the unit while holding down both switches.
•
The factory defaults are:
Setpoint: 0.782 V
Default Position: 9.9°
Gain: 25%
•
The unit will enter normal operation when the RAISE and LOWER buttons
are released.
Woodward
19
LCS A/F Ratio Control
Manual 26151
Chapter 6.
Troubleshooting
Suggested Troubleshooting Procedures
When a diagnostic fault is indicated, the following guidelines will help to quickly
find and solve the cause. The causes should be investigated in order; the
possible causes are listed in order from most likely to least likely. The table
below also lists trouble symptoms that may not set an indicated fault. Please
contact the nearest Woodward LCS A/F Ratio Control distributor or service
facility for further technical support.
Condition
FAULT/OPEN warning light on, no
HEGO voltage indication.
FAULT/OPEN & CLOSE lights
flashing, low HEGO voltage indication
(lean)—LCS A/F Ratio valve at wide
open limit without bringing HEGO
voltage back to set point.
FAULT/OPEN & CLOSE lights
flashing, high HEGO voltage indication
(rich) or no HEGO voltage indication—
LCS A/F Ratio valve at closed-off limit
without bringing HEGO voltage back
to set point.
Unstable HEGO voltage.
Slow HEGO voltage recovery after a
speed or load change.
High NOx emissions.
High CO (or HC) emissions.
No controller lights—no power supply.
20
Possible Causes
♦Initial start-up—HEGO sensor takes ~30 seconds to
warm up.
♦Open-loop operation manually selected with the
CONTROL MODE switch on the keypad.
♦HEGO sensor disconnected.
♦HEGO sensor failed—replace with new sensor.
♦Lean base fuel setting on carburetor—readjust according
to Calibration and Emissions Tuning procedure.
♦Air leak into the exhaust system upstream of the HEGO
sensor.
♦Rich base fuel setting on carburetor—readjust according
to Calibration and Emissions Tuning procedure.
♦Weak HEGO sensor signal from aging (prior to failure).
♦Excessive engine oil consumption or crankcase
ventilation (blow-by).
♦High control gain—lower according to Calibration and
Emissions Tuning procedure.
♦Low control gain—raise according to Calibration and
Emissions Tuning procedure.
♦HEGO voltage set point too low (lean).
♦Weak HEGO sensor signal from aging (prior to failure).
♦HEGO voltage set point too high (rich).
♦No switched 12V ‘run’ signal on black wire.
♦No connection to 12V main power supply (battery
connection) on red wire.
♦No connection to power supply ground on green wire.
♦Blown fuse (user installed) on main power supply.
♦Blown fuse on the control board in the LCS A/F Ratio
control box/keypad.
Woodward
Manual 26151
LCS A/F Ratio Control
Chapter 7.
Service Options
Product Service Options
The following factory options are available for servicing Woodward equipment,
based on the standard Woodward Product and Service Warranty (5-01-1205)
that is in effect at the time the product is purchased from Woodward or the
service is performed:
•
Replacement/Exchange (24-hour service)
•
Flat Rate Repair
•
Flat Rate Remanufacture
If you are experiencing problems with installation or unsatisfactory performance
of an installed system, the following options are available:
•
Consult the troubleshooting guide in the manual.
•
Contact Woodward technical assistance (see “How to Contact Woodward”
later in this chapter) and discuss your problem. In most cases, your problem
can be resolved over the phone. If not, you can select which course of
action you wish to pursue based on the available services listed in this
section.
Replacement/Exchange
Replacement/Exchange is a premium program designed for the user who is in
need of immediate service. It allows you to request and receive a like-new
replacement unit in minimum time (usually within 24 hours of the request),
providing a suitable unit is available at the time of the request, thereby
minimizing costly downtime. This is also a flat rate structured program and
includes the full standard Woodward product warranty (Woodward Product and
Service Warranty 5-01-1205).
This option allows you to call in the event of an unexpected outage, or in
advance of a scheduled outage, to request a replacement control unit. If the unit
is available at the time of the call, it can usually be shipped out within 24 hours.
You replace your field control unit with the like-new replacement and return the
field unit to the Woodward facility as explained below (see “Returning Equipment
for Repair” later in this chapter).
Charges for the Replacement/Exchange service are based on a flat rate plus
shipping expenses. You are invoiced the flat rate replacement/exchange charge
plus a core charge at the time the replacement unit is shipped. If the core (field
unit) is returned to Woodward within 60 days, Woodward will issue a credit for
the core charge. [The core charge is the average difference between the flat rate
replacement/exchange charge and the current list price of a new unit.]
Return Shipment Authorization Label. To ensure prompt receipt of the core,
and avoid additional charges, the package must be properly marked. A return
authorization label is included with every Replacement/Exchange unit that leaves
Woodward. The core should be repackaged and the return authorization label
affixed to the outside of the package. Without the authorization label, receipt of
the returned core could be delayed and cause additional charges to be applied.
Woodward
21
LCS A/F Ratio Control
Manual 26151
Flat Rate Repair
Flat Rate Repair is available for the majority of standard products in the field.
This program offers you repair service for your products with the advantage of
knowing in advance what the cost will be. All repair work carries the standard
Woodward service warranty (Woodward Product and Service Warranty
5-01-1205) on replaced parts and labor.
Flat Rate Remanufacture
Flat Rate Remanufacture is very similar to the Flat Rate Repair option with the
exception that the unit will be returned to you in “like-new” condition and carry
with it the full standard Woodward product warranty (Woodward Product and
Service Warranty 5-01-1205). This option is applicable to mechanical products
only.
Returning Equipment for Repair
If a control (or any part of an electronic control) is to be returned to Woodward for
repair, please contact Woodward in advance to obtain a Return Authorization
Number. When shipping the item(s), attach a tag with the following information:
•
name and location where the control is installed;
•
name and phone number of contact person;
•
complete Woodward part number(s) and serial number(s);
•
description of the problem;
•
instructions describing the desired type of repair.
CAUTION—ELECTROSTATIC DISCHARGE
To prevent damage to electronic components caused by improper handling,
read and observe the precautions in Woodward manual 82715, Guide for
Handling and Protection of Electronic Controls, Printed Circuit Boards, and
Modules.
Packing a Control
Use the following materials when returning a complete control:
•
protective caps on any connectors;
•
antistatic protective bags on all electronic modules;
•
packing materials that will not damage the surface of the unit;
•
at least 100 mm (4 inches) of tightly packed, industry-approved packing
material;
•
a packing carton with double walls;
•
a strong tape around the outside of the carton for increased strength.
22
Woodward
Manual 26151
LCS A/F Ratio Control
Return Authorization Number
When returning equipment to Woodward, please telephone and ask for the
Customer Service Department [1 (800) 523-2831 in North America or
+1 (970) 482-5811]. They will help expedite the processing of your order through
our distributors or local service facility. To expedite the repair process, contact
Woodward in advance to obtain a Return Authorization Number, and arrange for
issue of a purchase order for the item(s) to be repaired. No work can be started
until a purchase order is received.
NOTE
We highly recommend that you make arrangement in advance for return
shipments. Contact a Woodward customer service representative at
1 (800) 523-2831 in North America or +1 (970) 482-5811 for instructions and
for a Return Authorization Number.
Replacement Parts
When ordering replacement parts for controls, include the following information:
•
the part number(s) (XXXX-XXXX) that is on the enclosure nameplate;
•
the unit serial number, which is also on the nameplate.
How to Contact Woodward
In North America use the following address when shipping or corresponding:
Woodward Governor Company
PO Box 1519
1000 East Drake Rd
Fort Collins CO 80522-1519, USA
Telephone—+1 (970) 482-5811 (24 hours a day)
Toll-free Phone (in North America)—1 (800) 523-2831
Fax—+1 (970) 498-3058
For assistance outside North America, call one of the following international
Woodward facilities to obtain the address and phone number of the facility
nearest your location where you will be able to get information and service.
Facility
Brazil
India
Japan
The Netherlands
Phone Number
+55 (19) 3708 4800
+91 (129) 230 7111
+81 (476) 93-4661
+31 (23) 5661111
You can also contact the Woodward Customer Service Department or consult
our worldwide directory on Woodward’s website (www.woodward.com) for the
name of your nearest Woodward distributor or service facility.
Woodward
23
LCS A/F Ratio Control
Manual 26151
Engineering Services
Woodward Industrial Controls Engineering Services offers the following aftersales support for Woodward products. For these services, you can contact us by
telephone, by email, or through the Woodward website.
•
•
•
Technical Support
Product Training
Field Service
Contact information:
Telephone—+1 (970) 482-5811
Toll-free Phone (in North America)—1 (800) 523-2831
Email—[email protected]
Website—www.woodward.com
Technical Support is available through our many worldwide locations or our
authorized distributors, depending upon the product. This service can assist you
with technical questions or problem solving during normal business hours.
Emergency assistance is also available during non-business hours by phoning
our toll-free number and stating the urgency of your problem. For technical
support, please contact us via telephone, email us, or use our website and
reference Customer Services and then Technical Support.
Product Training is available at many of our worldwide locations (standard
classes). We also offer customized classes, which can be tailored to your needs
and can be held at one of our locations or at your site. This training, conducted
by experienced personnel, will assure that you will be able to maintain system
reliability and availability. For information concerning training, please contact us
via telephone, email us, or use our website and reference Customer Services
and then Product Training.
Field Service engineering on-site support is available, depending on the product
and location, from one of our many worldwide locations or from one of our
authorized distributors. The field engineers are experienced both on Woodward
products as well as on much of the non-Woodward equipment with which our
products interface. For field service engineering assistance, please contact us
via telephone, email us, or use our website and reference Customer Services
and then Technical Support.
24
Woodward
Manual 26151
LCS A/F Ratio Control
Technical Assistance
If you need to telephone for technical assistance, you will need to provide the following information.
Please write it down here before phoning:
General
Your Name
Site Location
Phone Number
Fax Number
Prime Mover Information
Engine/Turbine Model Number
Manufacturer
Number of Cylinders (if applicable)
Type of Fuel (gas, gaseous, steam, etc)
Rating
Application
Control/Governor Information
Please list all Woodward governors, actuators, and electronic controls in your system:
Woodward Part Number and Revision Letter
Control Description or Governor Type
Serial Number
Woodward Part Number and Revision Letter
Control Description or Governor Type
Serial Number
Woodward Part Number and Revision Letter
Control Description or Governor Type
Serial Number
If you have an electronic or programmable control, please have the adjustment setting positions or
the menu settings written down and with you at the time of the call.
Woodward
25
We appreciate your comments about the content of our publications.
Send comments to: [email protected]
Please include the manual number from the front cover of this publication.
PO Box 1519, Fort Collins CO 80522-1519, USA
1000 East Drake Road, Fort Collins CO 80525, USA
Phone +1 (970) 482-5811 • Fax +1 (970) 498-3058
Email and Website—www.woodward.com
Woodward has company-owned plants, subsidiaries, and branches,
as well as authorized distributors and other authorized service and sales facilities throughout the world.
Complete address / phone / fax / email information for all locations is available on our website.
06/5/F