485柴油机的配气机构的设计

485柴油机设计（配气机构）

摘要

本设计介绍了485柴油机配气机构的设计，主要是其各零部件的设计。本次设计的485柴油机主要用于轻型载货车。

配气机构的功用就是实现换气过程，即根据发动机气缸的工作顺序，定时的开启和关闭进排气门，以保证气缸排出废气和吸进新鲜空气。配气机构设计的好坏直接影响发动机整体的经济性和动力性，因此配气机构的设计在发动机整体设计上占有相当重要的作用。在气门选择上，采用每缸两个气门的方案，其优点是比较简单、可靠，对于自然吸气式柴油机可以提高新鲜空气的进气量，降低气缸的热负荷，增加气缸的耐久性和使用寿命。气门的驱动采用凸轮轴—挺柱—推杆—摇臂—气门机构。凸轮轴布置形式是下置式，采用的是整体式凸轮轴，这样的凸轮轴结构简单，加工精度高，能有良好的互换性。

本次配气机构的设计，主要包括进、排气门的设计，气门弹簧的设计，以及凸轮轴的设计。编写Matlab程序，计算得到挺柱升程表，绘出挺柱升程、速度、加速度曲线。

关键词：柴油机，配气机构，凸轮轴，气门

THE DESIGN OF VALVE TIMING MECHANISM

OF 485 DIESEL ENGINES

ABSTRACT

This thesis introduces the design of valve timing mechanism of 485 diesel engines, mainly the design of its various components. The 485 diesel engine in this design is mostly used in light truck.

The function of valve timing mechanism is to realize the exchange process, namely according to engine cylinder working order, ensure that the intake and exhaust valves open and close at the proper time. The valve gear play a direct impact on the economy and power parameters of the engine, therefore, the design of gas distribution agency in the overall design of the engine play a rather important role. Arranging two-valve per cylinder, the advantages are that it is relatively simple, reliable, for the naturally aspirated diesel engines can improve the fresh air into the cylinder, reduce the heat load of the cylinder to increase the durability of the cylinder and use life. The driving mechanism of valves is camshaft, tappet, pushrod, rocker, valve train. Camshaft arrangement is under the form of home-style, using the integral camshaft, such camshafts have simple structure, high precision machining, and good interchangeability.

This design, including exhaust valve, intake valve, valve spring, and camshaft. Write Matlab program, calculate tappet lift table, map the curves of tappet lift, speed and acceleration.

KEY WORDS: Diesel engine, Valve timing mechanism, Camshaft, Valve

目录

前言 (1)

第一章485柴油机的设计要求 (3)

第二章485柴油机工作过程热计算 (6)

§2.1485柴油机工作过程热计算已知参数 (6)

§2.2485柴油机工作过程热计算 (6)

§2.2.1 一般参数的计算 (6)

§2.2.2 进排气过程计算 (7)

§2.2.3 压缩终点参数计算 (8)

§2.2.4 燃烧过程的计算 (8)

§2.2.5 膨胀终点参数的计算 (8)

§2.2.6 指示参数的计算 (9)

§2.2.7 有效参数的计算 (9)

第三章485柴油机主要性能参数的选择 (10)

§3.1平均有效压力

P (10)

me

§3.2活塞平均速度

C (10)

m

§3.3行程缸径比D

S/ (11)

§3.4曲柄连杆比L

R/ (12)

§3.5气缸中心距 (13)

第四章配气机构总体布置 (14)

§4.1气门数目、布置和驱动 (14)

§4.2凸轮轴的布置和传动 (14)

第五章气门组的设计 (15)

§5.1气门的设计 (15)

§5.1.1 气门的工作条件与设计要求 (15)

§5.1.2 气门的结构和设计 (16)