Adjustable high-pressure/low-pressure EGR system for two-stage supercharged internal combustion engine and control method

Abstract

The invention relates to an adjustable high-pressure / low-pressure EGR system for a two-stage supercharged internal combustion engine and a control method For solving the problems that an existing supercharged engine cannot achieve EGR under full working conditions easily and cannot meet the requirement for a large EGR rate, an electric integrated EGR valve is designed to achieve high-pressure / low-pressure EGR system switching; EGR waste gas is guided in from a front gas inlet A of a high-pressure-stage turbine; under a small load working condition, the EGR waste gas communicates with a high-pressure EGR pipeline and is prevented from passing through a high-pressure-stage / low-pressure-stage gas compressor, the response speed is high, and a Venturi pipe is mounted on the high-pressure EGR pipeline, so that the EGR tolerance is further improved, and a relatively large EGR rate is achieved; and under medium and large load working conditions, the EGR waste gas communicates with a low-pressure EGR pipeline, so that a large pressure difference is obtained, and a large EGR rate is achieved. A crank-link mechanism is driven by a motor rotating valve rod to change the horizontal movement position of a valve block in the EGR valve, so that the circulation areas of the waste gas in the pipelines are adjusted, and continuous adjustment of the EGR rate is achieved. According to the adjustable high-pressure / low-pressure EGR system for the two-stage supercharged internal combustion engine, NOx emission can be reduced, the two pipelines share the EGR valve and an inlet air cooler, the structure is simple, and manufacturing and repairing cost is low.

Description

technical field [0001] The invention belongs to the technical field of internal combustion engines, and in particular relates to an adjustable high / low pressure EGR system and control method for a two-stage supercharged internal combustion engine. Background technique [0002] The increasingly stringent emission regulations have put forward higher requirements for reducing engine NOx and particulate (PM) emissions. It has become an important problem and challenge to achieve efficient and clean engine combustion to meet emission regulations. Exhaust gas recirculation (EGR) technology is considered to be one of the most effective means for modern engines to reduce NOx emissions. [0003] Compared with the single-stage supercharging diesel engine, the two-stage supercharging diesel engine has the advantages of achieving a higher supercharging ratio, increasing the amount of air inhaled into the cylinder per cycle, and increasing the circulating oil supply to improve the engine ...

AI Technical Summary

Problems solved by technology

[0003] Compared with the single-stage supercharging diesel engine, the two-stage supercharging diesel engine has the advantages of achieving a higher supercharging ratio, increasing the amount of air inhaled into the cylinder per cycle, and increasing the circulating oil supply to improve the engine power density, etc., but it is easy to cause cylinder Internal high-temperature oxygen-enriched combustion increases NOx emissions

The existing high / low pressure EGR can meet the demand of the traditional combustion method for a large EGR rate and can take into account the fuel economy under different working conditions, but the traditional high / low pressure EGR requires two sets of EGR systems, and the corresponding valves and coolers increase. Complicated piping, difficult assembly, high manufacturing and maintenance costs

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