Changeover valve, low temperature EGR cooler: Notes

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The changeover valve is integrated into the coolant hose towards the low temperature EGR cooler.

The high-pressure exhaust gas recirculation is a measure to reduce the formation of nitrogen oxide (NO_x ). Nitrogen oxides are created in great quantities when combustion runs with an excess air and at very high temperature. Here, the oxygen combines with the nitrogen of the combustion air to form nitrogen monoxide (NO) and nitrogen dioxide (NO₂ ). On the diesel engine, exhaust-gas recirculation is sometime required at idle speed and always in the partial load range, because a particularly high excess air is used there.

For the cooling of the exhaust gas for the high-pressure exhaust gas recirculation, a low temperature EGR cooler is used. The EGR cooler is integrated on the cold side after the radiator. As a result, the routed back exhaust gas can be further cooled down.