Hyundai Yanmar TNV Series Manual page 60

EGR control
The Eco-governor uses an electronic-controlled EGR valve to reduce the emission of NOx from 37 kW or
more engines.
The EGR valve is driven by a stepping motor. The opening (0 - 54 steps) of the EGR valve is adjusted
depending on the engine speed and load factor so as to control recirculation of exhaust gas. Figure 2-31
outlines the relationship between the number of steps and the flow rate.
The EGR valve does not open when the coolant temperature is lower than 60°C. This is because low
temperature corrosion due to condensation of exhaust gas components must be prevented.
CSD control
The fuel injection pump (MP pump) has a CSD valve mechanism that allows the fuel injection timing to
advance and the injection quantity to increase, thereby improving the cold start performance of the engine.
The Eco-governor has a solenoid valve CSD where the CSD can be opened or closed with a valve solenoid.
The E-ECU opens the CSD valve when the coolant temperature sensor detects that the coolant temperature
is 5°C or lower at cold start. The CSD valve closes when the coolant temperature rises to 5°C or five minutes
have elapsed after engine started.
TNV Application Manual
max
Valve opening point
0
0 6±1
Figure 2-31 EGR valve characteristics
Step
CONTROL SYSTEM
54
2-41