Symmetrical intake and exhaust cam of three-cylinder gasoline engine

Abstract

The symmetrical admission and exhaust cam for three cylinder gasoline engine has profile line with the work section equation of h=(hmax-hr)(1+c2A2+c4A4+cpAp+cqAq+crAr+csAs), where, h is the lift of the cam work section, hmax is the maximum lift and equals to 7.3-7.5 mm, hr is the lift of cam buffer section and equals to 0.3-0.35 mm, A is cam angle, p, q, r and s are indexes, c4=0.1, p=14, q=28, r=42, and s=56. The cam has base circle diameter of 33 mm, contact width to the jib of 10 mm, total contact angle of 167-172 deg, work section angle of 121 deg, and buffer section angle of 46-52 deg. The symmetrical admission and exhaust cam has the advantages of capacity of reaching excellent dynamic characteristic of gasoline engine and smooth running of the valve mechanism, and small thickness.

Description

technical field [0001] The invention belongs to the valve mechanism components of automobile engines, in particular to a symmetrical type of three-cylinder gasoline engine whose cam profile designed with a group of optimized parameters can not only meet the requirements of engine charging performance, but also ensure the stability of the valve mechanism. Intake and exhaust cams. Background technique [0002] The cam profile is a parameter that has an important influence on the performance of the engine. At present, the design methods that are widely used in the field of gasoline engines have the following forms: [0003] 1. Sinusoidal parabolic type: Its advantage is that the shortening of the positive acceleration section can make the lift curve plump, but the disadvantage is that the maximum positive acceleration increases sharply, which causes the vibration and noise of the valve mechanism to increase. [0004] 2. Combined polynomial type: It is characterized by the adva...

AI Technical Summary

Problems solved by technology

The disadvantage is that it is not easy to maintain the continuity of the derivative above the third order at the connection of each section, which affects the stability of the valve train.

[0005] 3. High-degree polynomial (high-square equation): Its advantage is that the acceleration curve is smooth, and the stability of the valve train is easy to ensure. The disadvantage is that the lift curve fullness coefficient is relatively low

Material consumption is high

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