Twostep throttle properties of hydraulic valve ports
YUAN Shi-Hao, YIN Chen-Bo, LIU Shi-Hao
(1.Institute of Automobile and Construction Machinery, Nanjing University of Technology, Nanjing, Jiangsu 210009, China; 2.Institute of Electrical and Mechanical Enginering, Hainan University, Haikou, Hainan 570228, China)
Abstract：The geometrical features of the U and V ports as well as their combinations (U-U, U-V and V-V) were analyzed, and then the throttle areas of those ports were calculated in a simplified manner so as to investigate two-step throttle properties of hydraulic valve ports. The ratio of throttling areas in terms of valve opening was obtained, and it was observed that the location of the minimum throttle area of U port varies; however, this is not true for V port. The cavitation functions of U and V ports against opening were obtained and the cavitation curves also were plotted by using cavitation number σ. According to the cavitation functions, it was observed that the severe cavitation zone in U port varies with opening, but that in V port is fixed. When the inlet and outlet of throttling port are reversed, there is an obvious change in cavitation number at the same opening. The stiffness analytical formulas for U and V orifices were derived and the stiffness curves were calculated under various pressure differentials across a port and openings. For a lower pressure differential and a smaller opening, a stiffer stiffness can be achieved.
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