EXHAUST GAS RECIRCULATION SYSTEM [SKYACTIV-G 2.5T]
id0116q4159300
Purpose, Outline
• The system recirculates the high-temperature exhaust gas to the combustion chamber and lowers the temperature in the combustion chamber. The following is achieved by recirculating the exhaust gas.
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― Knocking occurring from pre-ignition, in which the compression ratio increases excessively due to excessively-charged intake air, is prevented.
― Fuel economy has been improved by reducing*1 pumping loss, reducing cooling loss, and suppressing temperature increases in the combustion chamber.
― NOx generated when the combustion temperature is high has been reduced by lowering the temperature in the combustion chamber, improving environmental performance.
*1 :Due to the decrease in the oxygen level when the exhaust gas is recirculated to the intake side, the further induction of intake air results in reduced pumping loss.
• To perform optimum control according to the engine operation conditions, the EGR valve is opened and the exhaust gas is recirculated based on the information such as the exhaust gas pressure just after it passes through the EGR cooler.
Structure
System diagram
• The exhaust gas recirculation system consists of the following parts:
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Part name
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Reference
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EGR cooler
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EGR valve
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Exhaust gas pressure sensor
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Operation
• The operation of the exhaust gas recirculation system is as follows.
1. The exhaust gas just after combustion is cooled by the EGR cooler.
2. The EGR valve is operated and the cooled exhaust gas to be recirculated is adjusted based on the information such as the exhaust gas pressure from the exhaust gas pressure sensor.
3. The exhaust gas passing through the EGR valve is recirculated upstream (intake manifold) of the combustion chamber.
