Asymmetric vibration characteristics of two-cylinder four-stroke single-piston hydraulic free piston engine
来源期刊：中南大学学报(英文版)2014年第10期
论文作者：REN Hao-ling(任好玲) XIE Hai-bo(谢海波) YANG Hua-yong(杨华勇) GUO Jian-fei(郭剑飞)
文章页码：3762 - 3768
Key words：hydraulic free piston engine; free piston assembly; vibration system; nonlinear conservative autonomous system; asymmetry
Abstract: The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine (HFPE) were introduced. The basic vibration equation of free piston assembly (FPA) was established based upon the energy conversion between the injected fuel and the friction together with the load. Both the theoretical and numerical results show that the vibration system of FPA is a nonlinear conservative autonomous system in one cycle. The FPA vibration is symmetric with constant amplitude when FPA is only driven by the compression pressure in the compression accumulator and that in the combustion chamber. When considering the friction and load, FPA could still achieve a stable vibration after a few cycles’ adjustment whether the input energy is equal to the consumed energy or not. The vibration characteristics are different when FPA vibrates in the compression stroke and the expansion stroke, which is the unique feature of the single-piston HFPE.
REN Hao-ling(任好玲), XIE Hai-bo(谢海波), YANG Hua-yong(杨华勇), GUO Jian-fei(郭剑飞)
(State Key Laboratory of Fluid Power Transmission and Control (Zhejiang University), Hangzhou 310027, China)
Abstract:The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine (HFPE) were introduced. The basic vibration equation of free piston assembly (FPA) was established based upon the energy conversion between the injected fuel and the friction together with the load. Both the theoretical and numerical results show that the vibration system of FPA is a nonlinear conservative autonomous system in one cycle. The FPA vibration is symmetric with constant amplitude when FPA is only driven by the compression pressure in the compression accumulator and that in the combustion chamber. When considering the friction and load, FPA could still achieve a stable vibration after a few cycles’ adjustment whether the input energy is equal to the consumed energy or not. The vibration characteristics are different when FPA vibrates in the compression stroke and the expansion stroke, which is the unique feature of the single-piston HFPE.
Key words:hydraulic free piston engine; free piston assembly; vibration system; nonlinear conservative autonomous system; asymmetry
