All-working-condition EGR rate adjustable two-stage booster system of internal combustion engine and control method thereof

Abstract

The invention relates to a two-stage booster system capable of realizing all-working-condition EGR rate adjustability of an internal combustion engine. A gas loop, connected with an exhaust main pipe and an intake main pipe in parallel, of a traditional EGR two-stage booster system is connected with two bypass pipelines in parallel, wherein the first bypass pipeline is provided with a high-pressure-stage EGR pump in coaxial driving connection with a high-pressure-stage turbine and a high-pressure-stage air compressor and a low-pressure-stage EGR pump in coaxial driving connection with a low-pressure-stage turbine and a low-pressure-stage air compressor, and the second bypass pipeline is provided with a high-pressure-stage EGR pump bypass valve and a low-pressure-stage EGR pump bypass valve. The matching mode between the air pump bypass valves and EGR is adjusted according to the intake pressure difference change, so that a two-stage booster engine can satisfy the EGR rate requirements in the wider working condition range. The closing sequence of the high / low-pressure-stage bypass valves is set, and the valves are closed in proportion, so that the energy loss of coaxial pumps to the two-stage booster system and the influence of EGR pressure jump on combustion are reduced.

Description

technical field [0001] The invention belongs to a two-stage supercharging system of an internal combustion engine, in particular to a two-stage supercharging system capable of realizing the adjustable EGR rate of the internal combustion engine under all working conditions and a control method thereof. Background technique [0002] With the goal of energy saving and emission reduction, supercharging technology is widely used in heavy-duty diesel engines. Compared with the single-stage supercharging, the intake air volume of the two-stage supercharging diesel engine is significantly increased, which promotes the mixed combustion of oil and gas, and can increase the engine power and torque, but it is easy to cause oxygen-enriched combustion in the cylinder, and the NOx emission is larger than that of the single-stage supercharging , which in turn requires a large EGR rate, which helps to meet the requirements of engine emission regulations. At present, the traditional single-s...

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Problems solved by technology

[0004] In order to solve the problem that it is difficult to achieve better exhaust gas recirculation within the full load range of the two-stage supercharged engine with only a single EGR pump, the present invention proposes a two-stage supercharger with adjustable EGR rate under all working conditions of the internal combustion engine. System and its control method

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