Low-pressure EGR introduction device capable of realizing high EGR rate and low-pressure EGR introduction method

Abstract

The invention discloses a low-pressure EGR introduction device capable of realizing high EGR rate and a low-pressure EGR introduction method. Recycled exhaust gas is led out through the upper side and lower side of a turbine, passes through only one EGR valve and an EGR cooler, and then enters the upper side of an air compressor. According to the scheme, two paths of EGR exhaust gas are introduced into the upper side of the air compressor through one electric control valve, so that a low-pressure EGR scheme is obtained. Under the high-rotating speed condition, exhaust gas can be introduced from the upper side of the turbine. Under the low-rotating speed condition, exhaust gas can be introduced from the lower side of the turbine. Compared with a high-and-low-pressure double-circuit EGR system, the device and method have the advantages that high EGR rate can be realized, requirements for EGR under high-and-low rotating speed and load conditions can be met, and emission of NOx of an engine can be effectively reduced; meanwhile, two paths of EGR exhaust gas share one EGR valve and one EGR cooler, structure is simple, weight is reduced, packaging complexity is reduced, and manufacturing cost is low.

Description

technical field [0001] The invention belongs to the technical field of EGR devices, and in particular relates to a low-pressure EGR introduction device and a low-pressure EGR introduction method for realizing a large EGR rate. Background technique [0002] With the increasingly stringent emission regulations, the control of engine emission pollutants focuses on the control of NOx and PM emissions. For NOx emissions, the most mainstream technology is to use EGR and delayed injection, but because delayed injection will increase the fuel consumption rate and have a negative impact on fuel economy, in order to reduce NOx, most of them use EGR schemes . [0003] The introduction of EGR is not a problem on naturally aspirated engines. Generally speaking, the exhaust pressure is higher than the intake pressure, and the exhaust gas can easily enter the cylinder to achieve circulation. However, since naturally aspirated engines are generally used on non-roads, the emission standard ...

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Problems solved by technology

However, it should also be noted that the use of high-low pressure dual-circuit EGR technology requires additional devices such as exhaust back pressure valves and air intake throttle valves to increase the EGR rate. However, the design of the two EGR systems will cause complex piping and system Difficult layout and other issues, and both the high and low pressure EGR systems require EGR valves and corresponding coolers, resulting in high manufacturing and maintenance costs

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