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이종훈(Jong-Hoon Lee),이연원(Yeon-Won Lee),김재환(Jae-Hwan Kim) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
As environmental problems are important, automotive industries are developing various techniques to prevent air pollution. One of these is Positive Crankcase Ventilation (PCV) system. It removes blowby gas which includes about 30% hydrocarbon of total generated quantity. In this system, a PCV valve is attached in a manifold suction tube to control the flow rate of blowby gas which generates differently according to various operating conditions of an automotive engine. As this valve is very important, designers are feeling to design it because of both small size and high velocity. For this reason, we numerically investigated to understand both spool dynamic motion and internal fluid flow characteristics. As the results, spool dynamic characteristics, i.e. displacement, velocity, acting force, increase in direct proportion to the magnitude of differential pressure and indicate periodic oscillating motions. And, the velocity at the orifice region decreases according to the increase of differential pressure because of energy loss which is caused by the sudden decrease of flow area at the orifice region and the increase of flow volume in the front of spool head. Finally, the mass flow rate at the outlet decreases with the increase of spool displacement. We expect that PCV valve designers can easily understand fluid flow inside a PCV valve with our visual information for their help.
Moving Mesh를 이용한 PCV 밸브의 내부유동 수치해석
이종훈(J. H. Lee),이연원(Y. W. Lee),김재환(J. H. Kim) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
A great deal of exhaust gas inside a combustion room goes out through exhaust pipe but residual gas, is called "Blowby gas", enters the crankcase through a small gap between the piston and the cylinder wall. Here, if the crankcase isn't vented, this causes many bad effects such as lubricant oil contamination, corrosion by that and crankcase explosion by rising pressure. So, most automobiles are constituted with a PCV (Positive Crankcase Ventilation) system to prevent previous problems. PCV valve is the most important part in this ventilation system. When companies are manufacturing new engines, engineers are designing it depending on their experiments than theoretical knowledge. Much effort and many times are needed for new development. This study will show quantitative results to increase the possibilities of reduction of developing time.
이종훈(J. H. Lee),이연원(Y. W. Lee),김재환(J. H. Kim) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In the technical development of automobiles, environmental effort is risen with air pollution problem. Hydrocarbon (HC), one of dangerous pollutants in automobiles, is generated about 20~35% in total amount by crankcase blowby gas. A PCV valve eliminates this gas using recirculation loop to control it automatically using return spring. The PCV valve is very small component in an automotive engine but it is very important. Although it has very simple operating principle such as the spool is moved by force balance between fluid force and elastic force, designing a PCV valve is difficult for interaction between fluid and solid. In this study, our purpose is to develop a design program for PCV valve and we verify its efficiency. We used both Euler's equation and 4th order Runge-Kutta method to predict spool displacements and flow areas. Comparing with real products, we found that both spool diameter and displacement were predicted well. But, in comparison with flow rate we could found its difference because of the assumption of non viscous flow, that is Euler's equation.