外文翻譯--挖掘機臂液壓系統(tǒng)的模型化參量估計-其他專業(yè)(參考版)
2025-01-23 10:10本頁面
【正文】 A)． w Flow of boom cylinder under electrohydeaulic proportional value controlled by step current 5 Conclusions （ 1） The mathematic model of electro— hydraulic system is developed according to the characteristics of excavator． It is assumed that the flow across the valve is directly proportional to the size of valve orifice， and the influence of intemal and extemal leakage of hydraulic system is ignored． The simplified model can be obtained： )](/[)]()([)( 212021 asasasssFbsXbsY cv ???? where represent the displacement of piston and the displacement of spool． （ 2） From the model of electro— hydraulic system， we can obtain the equivalent mass BOlJm 12/? ， bearing force )(31211 3121 ??? ??? GOGOGOl lmglmglmF , flow gain coefficient of value KqKl=104m3/(sand G3180。m. Comparing Eqn． (9)with Fc=mac， the equivalent mass at point B can be given： BOlJm 12/? (11) Estimation for load on hydraulic cylinder The equivalent moment equation of manipulator to O1 is ??? ??? 3121111 321s i n GOGOGOBOc glmglmglmlF ? (12) where ?? 2111 , GOGO lland ?31GOl are the length from pointO1 to point G1180。m, J2= BQl1 is the length from point O1 to point B． According to the rotating law： M=J? ,we get (8) w BOcBOc lJalF11 /s ins in ?? ? that is BOcc lJaF12/? （ 9） where J is the equivalent moment inertia of manipulator to point O1,kg ? ?2212122 AVAVa c ?? ? . 4 Parameters estimation From the process of modeling and Eqn． (7)， it is clear that all parameters in the simplified model are related to the structure。a0=V1V2m。 ? ?122211 / AAVAKb qc ??? ? 。 1p? and 2p? are the two orifices pressure， respectively, M Pa． When the flow of excavator is not saturated， p? is a nearly constant． In this work， the value was tested and gotten by experiment． In ， ps， p1s,and p? represent the system pressure， the load sense valve pressure and the diference of pressure, respectively. The pressure experiment curves of the system show the variation of three kinds of pressures． Although Ps and pls change with load， their difference does not change with load， the value approximates to ， the effect of on the flow across the valve can be neglected． It is assumed that the flow across the valve is proportional to the size of orifice valve， and the flow is not influenced by ? ? 0)(/2 1 ??? tIppwxc rvd ，? (2) 0)(2 ?? tIpwxc vd ，? ? ? 0)(/2 2 ??? tIppwxc rvd ，? 0)(2 ?? tIpwxc vd ，? (3) w load． Then， Eqn． (2) can be simplified as Q1=Kqxv(t),I(t)≥0 (4) where is the flow gain coefficient of valve, m2／ s, and ?/2 pwcK dq ?? Curves of pressure experiment under boom moving condition Continuity equation of hydraulic cylinder Generally speaking， construction machine does not permit external leakage． At present， the external leakage can be controlled by sealing technology． On the other hand，it has been proven that the internal leakage of excavator is quite little by experiments． So, the influence of internal and external leakage of hydraulic system can be ignored． When the oil flows into head side of cylinder and discharges from rod side， the continuity equation can be written as cpVyAQ ?/1111 ?? ?? cpVyAQ ?/2222 ?? ?? where V1 and V2 are the volumes of fluid flowing into and out the hydraulic cylinder, m3 ； c? is the effective bulk modulus(including liquid， air in oil and so on)， N/m2． Force equilibrium equation of hydraulic cylinder It is assumed that the mass of oil in hydraulic cylinder is negligible,and the load is rigid. Then the force equilibrium equation of hydraulic cylinder can be calculated
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