C. Total Operation USA Model Year 1980
OPERATION EXHAUST GAS RECIRCULATIONC. Total operation USA model year 1980
EGR begins:
Above approx. 40°C/104°F coolant temperature: After the free travel of the free travel rod has been eliminated.
In partial load range up to final EGR shutoff shortly before full throttle stop.
Below approx. 40°C/104°F coolant temperature the thermovalve (36) is closed. The vacuum cannot move to EGR valve. There will be no EGR.
Starting at a coolant temperature of approx. 40°C/104°F the thermovalve (36) opens. The vacuum, at idle 350-500 mbar, moves to the switchover valve (64a).
If the control linkage is at the idle speed stop, the EGR valve (60) is vented externally. There will be no EGR.
If the throttle linkage is opened so that the free travel in the free travel rod is eliminated, the switchover valve (64a) is operated by the cam of the guide lever (68). The vacuum now moves via the two switchover valves (64a and 64b) to the EGR valve and opens the valve completely, This results in max. possible EGR.
At increasing load the vacuum is gradually decreased via vacuum control valve (65). This also reduces the amount of recirculated exhaust gas. Shortly before reaching full throttle position, the switchover valve (64b) is vented to atmosphere via cam of guide lever (68). The vacuum is completely removed, there is no EGR.