A Design Method of Gas Distribution Cam Profile

Abstract

The invention provides a valve cam profile design method. The valve cam profile design method comprises the steps that a symmetrical and continuous cam acceleration curve is determined firstly, the parameters of a valve cam are determined according to the cam acceleration curve, then a corresponding mathematical model expression is obtained according to the acceleration curve and the parameters of the valve cam, and finally a cam profile is obtained according to the solution of the mathematical model expression and the parameters of the valve cam. According to the valve cam profile design method, by inputting a small number of design parameters, the cam profile with the maximum fullness coefficient can be obtained, the profile has the continuous non-step characteristic, and the performance of the valve mechanism can be improved.

Description

technical field [0001] The invention relates to the field of internal combustion engine design, in particular to a method for designing a gas distribution cam profile of an internal combustion engine. Background technique [0002] The gas distribution mechanism is an important component of the internal combustion engine. Its function is to realize the replacement of the cylinder working fluid between cycles, and to accurately open and close the intake and exhaust valves according to the ignition sequence of the internal combustion engine to ensure that the cylinder can discharge exhaust gas and Inhale a fresh charge. The design of the valve train directly affects the power, economy, emission performance, vibration and noise of the internal combustion engine. The common gas distribution mechanism is basically driven by the gas distribution cam, so the performance of the gas distribution device mainly depends on the design of the cam profile. [0003] At present, according t...

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Problems solved by technology

[0004] Although the above-mentioned gas distribution cams have their own advantages, such as good inflation performance and stable operation, they all have an obvious shortcoming: the function curve is discontinuous, resulting in a large impact, which accelerates the wear and tear of the cam.

[0005] In response to the above problems, Beijing Institute of Technology provides an optimal design method of the valve cam profile (patent number: CN200910237445.0), in the area where the acceleration step occurs, the method of connecting the curve with the acceleration slope of the highest point to 0 is used to solve the problem The above problem, but it only considers the acceleration step in the middle section, and the acceleration slope at the beginning and end is not considered; in addition, it contains as many as 7 optimized design parameters, which is too complicated and difficult to optimize the design

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