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近年来.一些船用低速柴油机开始采用液压配气机构。本文研究了液压配气机构的工作机理,对其建立了由一维瞬变流和质量—弹簧系统相结合的动力学模型。该模型对应于偏微分方程和常微分方程相结合的方程组,可以用有限差分法或特征线方法求解。文章对机构的复杂边界条件作了简化并用数学方法进行处理,给出了一个算例,得到了气门升程及液压管油压随凸轮转角变化的曲线,计算结果与实测曲线吻合较好。本文还讨论了下列问题:差分格式的步长对计算误差的影响;阻尼对机构稳定性的作用以及机构泄漏对气门运动的影响,并将这些关系用图形显示出来。
In recent years, some marine low-speed diesel engines have begun to adopt hydraulic distribution mechanisms. In this paper, the working mechanism of hydraulic valve train is studied, and a dynamic model combining one-dimensional transient flow with mass-spring system is established. The model corresponds to the system of equations combining partial differential equations and ordinary differential equations, and can be solved by the finite difference method or the characteristic line method. In this paper, the complex boundary conditions of the mechanism are simplified and dealt with mathematically. An example is given, and the curves of the valve lift and hydraulic pressure with the change of the cam angle are obtained. The calculated results are in good agreement with the measured curves. The paper also discusses the following issues: the effect of the step size of the difference scheme on the calculation error; the effect of damping on the stability of the mechanism and the effect of the mechanism leakage on the valve movement, and graphically displays these relationships.