Woodward GECO, Техническое руководство, Страница: 15 / 90

Manual 03554 GECO

Stoichiometric
Woodward 7
+
Post-Cat
Exhaust
Oxygen
(EGO3)
EGO1
Base
+
-
+
+
+
-
Fuel
Trim
Valve
Pre-Cat
Exhaust
Oxygen
(EGO1)
Filter
Filter
EGO3
Target
EGO1 Target
+
EGO3
Base
+
Figure 2-5. Basic Control Logic for Post-catalyst EGO Control
EGO3 Offset
This EGO3 Base value may vary several millivolts from engine to engine, catalyst
to catalyst, and load to load. Some engines operate with varying loads. In order
to keep such an engine and catalyst at optimum performance, the EGO3 Base
value may need to be adjusted. The required adjustment can be entered into the
EGO3 Offset table in the GECO control so that it can adjust the EGO3 Base
value by adding the offset to the base value at different loads. The GECO control
keeps track of engine load by monitoring the intake manifold pressure (MAP) and
engine speed (MPU). The intake manifold pressure and engine speed are used
to calculate an approximate engine fuel flow is then used as a load indicator. The
load range of the engine is divided into eight segments. An EGO3 Offset value
can be manually entered for each of these load levels with this feature. The
EGO3 Base value can be offset to provide the optimum EGO3 Target value over
the entire operating range of the engine.
+
Post-Cat
Exhaust
Oxygen
(EGO3)
EGO1
Base
+
-
+
+
+
-
Fuel
Trim
Valve
Pre-Cat
Exhaust
Oxygen
(EGO1)
Filter
Filter
EGO3
T
a
rget
EGO1 Target
+
EGO3
Base
+
EGO3 Offset Table
Fuel Flow EGO3
0.00 -0.010
2.00 -0.005
4.00 -0.000
6.00 +0.005
8.00 +0.010
10.00 +0.008
12.00 +0.007
14.00 +0.005
Intake
Manifold
Pressure
(MAP)
Fuel Flow
Estimation
Speed
Figure 2-6. Control Logic with EGO3 Offset