Research on modeling and simulation of a hydraulic cylinder with special buffer structure

Buffer structures inside hydraulic cylinder can greatly reduce hazards of hydraulic shock, such as vibration, noise and temperature rise of oil. And they are widely used in various industries, especially when the hydraulic system has high pressure and high speed. General buffer structure is column-shape, taper-shape, inclined-shape, parabola-shape or sidestep-shape plunger piston, the shape of which is relatively regular. This paper studies on the cushioning process of a hydraulic cylinder with a kind of Special buffer structure inside it, the irregular shape of which will make flowing state complicated when it works. It will become difficult to establish the flow equation of the three cushion stages, namely across sectional area shrinking, sharp edge throttling and aperture throttling. They are divided according to the cause of pressure loss. Compared to the fix size of aperture of general buffer structure, The irregular shape can be regarded as one with variable length and height of aperture. This paper takes the irregular shape plunger piston analogy to a large number of taper-shape element and column-shape element, then uses the approximate integral method to calculate the quantity of flow according the formula of taper-shape and column-shape plunger piston. Then the complete mathematical models are established and corresponding simulations are made, based upon which the influence of the structural parameters on the cushion velocity and the pressure of cushion chamber is analyzed.