Design Of Positive Crankcase Ventilation System For DA465QA Engine

For the development of mini gasoline engine DA465QA, through enginebench test and vehicle road test, for the positive crankcase ventilation systemwith single line structure of the DA465QA, the engine crankcase pressure instandard conditions is positive, there is oil stain on air filter element. At thesame time with the vehicle engine in EFI matching, it is found that the threeway catalytic converter is with excessive oil combustion products, the intakemanifold pressure chamber has accumulated oil signs, resulting in emissiondeterioration test failure. After verification, the above are all caused bypositive crankcase ventilation system design, the gasoline engine crankcaseventilation system is developed.Based on the study of development performance need for exteriorconnection piece and air filter assembly of positive crankcase ventilationsystem, by using computer software simulation, combined with enginebench test and data analysis, the air filter assembly pressure, ventilation hosedesign, PCV valve flow characteristics and the system of overall arrangement,and the crankcase ventilation system specific relations are all introduced, butalso the relationship and influence for the components and parts areexplored.According to the engine development project needs of Dongan, in apositive crankcase ventilation system development, taking DA465QA engineas the research object, at all engine operating conditions, the positivecrankcase ventilation system needs to keep the negative pressure in thecrankcase, while avoiding excessive interference of intake system. And to ensure the normal work of the system, engine performance is not abnormal,various parts design of the system are reasonable, complete function isneeded. Through the air filter assembly optimization design, ventilation tubelayout design and PCV valve flow design, explore positive crankcaseventilation system development process, simplify the design process, improveefficiency, avoid the fault. DA465QA engine related test shows that, thedesign experience was very effective, parts development are reasonable,achieve the initial design target, to ensure that the engine relatedrequirements, it has certain value.