490QB柴油机设计(配气机构)概论

490QB柴油机设计（配气机构）

摘要

本设计的发动机机型为490QB柴油机，介绍了490QB柴油机的配气机构设计，配气机构各零件的详细设计。依照本柴油发动机的设计技术要求，可以确定本柴油机的结构以及相关尺寸。本机采用 形燃烧室，凸轮轴中置，龙门式机体方案。为了使本次设计满足设计要求，所以根据内燃机工程师手册，对本机进行工作过程热计算，结果表明此次设计满足其经济性和动力性要求。

发动机通过配气机构实现换气，即排出本循环已燃混合气和下一个循环吸入新鲜充量的进气排气过程，对于四冲程发动机来说，从排气门打开到进气门关闭的整个过程为换气过程。而发动机动力性和经济性的好坏，在很大程度取决于换气过程的完善程度，因此配气机构的设计在本发动机设计中占有相当重的位置。而配气机构设计的核心为提高充气效率，降低换气损失，进而改善了发动机的经济性和动力性。设计气门采用双气门方案，即一进一出两气门，双气门方案结构简单，工作可靠，完全满足进排气要求，降低制造成本。气门的驱动采用凸轮轴—挺住—推杆—摇臂—气门的驱动方案。凸轮轴采用中置方案，形式为整体式凸轮轴，全支撑，满足强度要求，结构简单，加工精度高，具有很好的互换性。

本次设计主要包括气门弹簧，进排气门，进排气道和凸轮轴设计，而凸轮形状采用函数凸轮设计，由Mat lab程序计算得到挺柱的升程，速度，加速度，绘制曲线。

关键词：柴油机，凸轮，气门

THE 490QB DIESEL ENGINE DESIGN（PISTON AND

CONNECTING ROD）

ABSTRACT

The design of the diesel engine models for the 490QB introduced 490QB diesel engine valve train design, detailed design of each valve train parts. In accordance with the technical requirements for diesel engines, you can determine the structure and size of the diesel engine. The machine adopts the shape of the combustion chamber, the camshaft position, gantry body program. In order to meet the design requirements of this design, it is based on the internal combustion engine engineer manual process to work on the machine thermal calculations, the results show that the design meets its economy and power requirements.

Engine for ventilation through valve body, the discharge of the circulating air and fuel mixture is next cycle inhale fresh charge intake and exhaust, for four-stroke engines, the exhaust valve to open the intake valve closing the whole process of the ventilation process. The engine power and economy is good or bad, to a large extent depend on the degree of perfection of ventilation process, so Valve design occupies very heavy position in this engine design. The core Valve designed to improve volumetric efficiency, reduce ventilation losses, thereby improving the economy of the engine and power. Valve double valve design scheme, namely one into a two-valve, dual valve scheme is simple, reliable, fully meet the requirements of the intake and exhaust, reduce manufacturing costs .Valves driven by the camshaft - tappet - putt - rocker - valve drive solutions. Camshaft scheme used in the home, in the form of the monolithic camshafts, fully supported to meet the strength requirements, simple structure, high precision, with good interchangeability.

The design includes valve springs, intake and exhaust valves, and intake and exhaust camshafts road design, and the use of a cam-shaped cam design function, calculated by the Mat lab program tappet lift, velocity, acceleration, plotted.

Key words: diesel engine, cam, valve