A method for reducing emission of exhaust gas retained in diesel engine Miller cycle

Abstract

The invention discloses an emission reduction method for retained waste gas in a diesel engine in a Miller cycle. As the phase position design is performed for an admission cam, an intake valve of the diesel engine is closed in the ascending process of a piston, and part gas entering a cylinder is pushed into an intake pipe to realize the delayed-closing type Miller cycle working process of the intake valve of the diesel engine; and as the phase position design is performed for an exhaust cam, an exhaust valve is closed beforehand, so that part burnt waste gas is retained in the cylinder, and is mixed with fresh mixed gas to participate in the next circulating combustion. The diesel engine solves the difficulty of excessive impulse temperature in the cylinder in a traditional IEGR technology; compared with an EEGR technology, the method can be applied to various complex working conditions, is wider in adaptability and lower in cost, and can achieve better emission reduction efficiency; and compared with a traditional IEGR technology under a diesel cycle, the method has the characteristics of reducing the temperature of the gas in the cylinder after the adiabatic compression, facilitates to improve the high-temperature environment in the cylinder, weakens the NOx generation, and achieves the NOx emission reduction effect which can not be achieved by the single IEGR technology.

Description

technical field [0001] The invention relates to the technical field of diesel engine emission reduction, in particular to a method for reducing emission of exhaust gas retained in the diesel engine Miller cycle. Background technique [0002] Theoretical and applied studies of many internal and external purification technologies of diesel engines have shown that exhaust gas recirculation technology (EGR) is one of the effective measures to reduce nitrogen oxide (NOx) emissions from diesel engines. [0003] The mechanism of EGR emission reduction is to reduce the oxygen concentration of the gas in the cylinder by mixing a certain proportion of burned exhaust gas into the cylinder; through the increase of the total heat capacity of the gas in the cylinder by the burned exhaust gas, the purpose of reducing the maximum combustion temperature is achieved. The reduction of oxygen content and temperature in the diesel engine cylinder suppresses the NOx that is easy to form under hig...

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Problems solved by technology

[0007] The invention discloses a method for reducing the emission of exhaust gas retained in the diesel engine Miller cycle, which is used to solve the problems of high temperature of the charge in the cylinder and poor control effect of NOx generation in the traditional IEGR technology, so that it can be compared with the existing one after use. Compared with EEGR technology, it not only has better emission reduction effect, but also has low cost and wide applicability, and can be used in various complex working conditions

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