Effects of shifting time on pressure impact in hydraulic systems

Abstract

The limitations in existing measures for absorbing pressure impact in hydraulic systems were summarized in this paper. Based on the forming principle of the oil in a hydrostatic closed pressure chamber, the underlying reasons of the pressure impact were analyzed theoretically, the intrinsic laws that the extent of the pressure impact in hydraulic oil lines are affected by some factors, such as oil elastic modulus, oil line’s geometrical volume, and changing rate of oil volume versus time etc, were discussed. Experimental investigations into pressure impact in all pressure chambers because of shifting were conducted under different working conditions by employing a special experimental system. The effects of shifting time on pressure impact were studied. A new concept with universal meaning, i. e. optimal shifting time, and its characterizing parameter and the methods of shifting at optimal shifting time were also proposed. The results show that shifting time lag Δt is of rationality and maneuverability. The higher the working pressure, the shorter the shifting time.

Keywords

hydraulic system / shifting time / pressure impact / experiment / law

References

[1] WaltersJ R BHydraulic and Electric-hydraulic Control Systems [M], 2000, London, Kluwer academic publishers

[2] LuYong-xiangHandbook of Hydraulic and Pneumatic Technology [M], 2002, Beijing, China Machine Press(in Chinese)

[3] LeiTian-jueNew Hydraulic Engineering Handbook [M], 1998, Beijing, Beijing University of Technology Press(in Chinese)

[4] BlankaD, PavelN. Measurement and simulation of hydraulic pressure impact [A]. Management and Control of Production and Logistics (MCPL 2000) Proceedings Volume from the 2nd IFAC/IFIP/IEEE Conference[C], 2001, Kidlington, Elsevier Sci: 571-574

[5] YangGuo-ping, LongGuo-jian, YangXiang-bi, et al.. The research of precursor control valve of a new hydraulic impact hammer [J]. China Mechanical Engineering, 2002, 13(10): 891-893(in Chinese)

[6] YangXiang-bi, YangGuo-ping, LongGuo-jian, et al.. Research of a pressure feedback full hydraulic pressure hydraulic impacter with strike energy and frequency adjusted independently [J]. China Mechanical Engineering, 2002, 13(23): 2044-2047(in Chinese)

[7] YuanGuang-jie, ChenPing, HuangWan-zhi. Experimental research on back-pressured hydraulic impactor [J]. Natural Gas Industry, 2002, 22(4): 50-52(in Chinese)

[8] YangGuo-ping, LiuZhong, DingWen-si, et al.. Research on the precursor control valve of a new hydraulic impact hammer [J]. Mechanical Science and Technology, 2001, 20(6): 836-838(in Chinese)

[9] Mikheev, Yu S. Calculation of hydraulic impact in the line ended with damper [J]. Izvestiya VUZ: Aviatsionnaya Tekhnika, 1991(4): 18–21.

[10] TownsendD, ParkN, DevallP M. Failure of fluid filled structures due to high velocity fragment impact [J]. International Journal of Impact Engineering, 2003, 29(1–10): 723-733

[11] SoyamaH, LichtarowiczA, MommaT, et al.. A new calibration method for dynamically loaded transducers and its application to cavitation impact measurement [J]. Transactions of the ASME, Journal of Fluids Engineering, 1998, 120(4): 712-718

[12] CaoBin-xiang, ChenGuo-an, FanTian-jin, et al.LuYong-xiang, et al.. Experimental and control research on pressure impact during spool shifting of directional-control valves [A]. Proceedings of the sixth international conference on fluid power transmission and control[C], 2005, Beijing, International Academic Publisher: 873-876(in Chinese)