车用柴油机4气门结构设计研究

运用一维气体流动模拟软件BOOST，对某公司的一款2气门柴油机改成4气门后的流动过程建立计算模型，对改型后柴油机的主要结构参数，如气门直径、气道直径、歧管直径、配气相位进行换气过程模拟计算。当该机采用直径分别为39．0mm的进气门、37．5～30．0mm的渐缩进气道、53．0mm的进气歧管、32．5mm的排气门、23．0mm的等直径排气管、32．5mm的排气歧管时可以获得较好的换气性能。通过对配气相位进行改进和优化，可以在整个转速范围内得到较理想的换气性能。

Structure Design of 4-Valve Vehicle Diesel Engine

In this paper a model for calculating the flow process of a diesel engine, modified from 2-Valve to 4-Valve inlet system, was presented with one dimensional gas flow simulation software BOOST. The primary structural parameters of 4-Valve diesel engine, such as inner valve seat diameter, port diameter, manifold branch diameter and valve timing, were optimized through calculating the scavenging process. Better scavenging performance could be achieved for the intake inner valve seat of 39.0mm, a convergent intake port from 37.5mm to 30.0mm, a intake manifold branch of 53.0mm, an exhaust inner valve seat of 32.5mm, straight exhaust pipe of 23.0mm and a exhaust manifold branch of 32.5mm. The realistic scavenging performance over a wide range could be obtained through valve timing optimization.