Exhaust gas recirculation system and engine

Abstract

The invention discloses an exhaust gas recirculation system and an engine. The exhaust gas recirculation system comprises a first turbosuperchager and a second turbosuperchager which are in series connection. An outlet of a power turbine of the second turbosuperchager is connected with an exhaust pipe, an inlet of a gas compressor of the second turbosuperchager communicates with the exhaust pipe through an EGR gas getting pipe, an outlet of the gas compressor of the second turbosuperchager communicates with a gas inlet manifold through a low-pressure EGR waste gas pipe, the system repeatedly uses waste gas energy to push power turbines of the two stages of turbosuperchagers, the waste gas use rate is improved, energy losses brought by front getting of waste gas of the turbosuperchagers canbe reduced, the first turbosuperchager can be matched with the efficient gas compressor, the oil losses are reduced, the exhaust temperature is improved, the conversion efficiency of a post-treatmentsystem is improved, meanwhile, the EGR gas pressure and waste gas amount can be improved, a gas inlet throttling valve is not needed, the conditions of pump gas losses, engine oil consumption increasing, particle discharge increasing and the like are avoided, and engine economy is improved.

Description

technical field [0001] The invention relates to the technical field of engine EGR, in particular to an exhaust gas recirculation system and an engine. Background technique [0002] Exhaust gas recirculation (EGR) is a modern diesel engine to reduce NO x One of the most effective means of emission. EGR can reduce the oxygen concentration and maximum combustion temperature in the cylinder to reduce NO x Effect. EGR is considered to be one of the important technical means for diesel engines to meet China IV and later emission regulations. [0003] Existing EGR systems such as figure 1 As shown, the exhaust manifold 03 of the engine 01 is connected to the turbine 06 of the turbocharger, the exhaust pipe 07 is connected behind the turbine 06, one end of the EGR pipeline 010 takes air from the front of the turbine 06, and the other end is connected to the engine 01 The intake manifold 02 is provided with an EGR valve 04 on the EGR pipeline, the inlet of the compressor 05 of t...

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Problems solved by technology

[0003] Existing EGR systems such as figure 1 As shown, the exhaust manifold 03 of the engine 01 is connected to the turbine 06 of the turbocharger, the exhaust pipe 07 is connected behind the turbine 06, one end of the EGR pipeline 010 takes air from the front of the turbine 06, and the other end is connected to the engine 01 The intake manifold 02 is provided with an EGR valve 04 on the EGR pipeline, the inlet of the compressor 05 of the turbocharger is connected to the intake pipe 08, and the outlet of the compressor 05 communicates with the intake manifold 02. When the EGR valve is opened, part of The exhaust gas enters the turbine 05 to pressurize the intake air, and the remaining exhaust gas passes through the EGR valve 04 and the EGR cooler 011, mixes with the pressurized air, and then enters the intake manifold 02 of the engine 01. Due to the improvement of the efficiency of the turbocharger, the increase The intake pressure after compression will be higher than the exhaust pressure in front of the vortex in a relatively large speed range, and it is difficult to obtain a sufficient EGR rate simply by opening the EGR valve

In order to obtain a sufficiently large and adjustable EGR rate, reduce NO x , the commonly used method is the intake throttle valve 09 on the intake line, the EGR exhaust gas is mixed with the charge air downstream of the intake throttle valve 09, but the intake throttle valve 09 will significantly increase the pump while increasing the EGR rate Gas loss, resulting in increased engine fuel consumption, increased particulate matter emissions, resulting in economical deterioration

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