| Pump controlled cylinder technology includes pump controlled symmetrical cylinder and differential cylinder.After more than 20 years of efforts,pump controlled symmetrical cylinder technology has been very mature.However,the widely used differential cylinder in hydraulic control system,due to the different effective area of the two cavities,leads to the unequal flow in and out of the two cavities,which limits the performance of pump controlled differential cylinder control system,and has become the key technology restricting the popularization and application of this technology Difficulties in operation.Asymmetric pump is the core component of the differential cylinder,which has one suction port and two discharge ports,which can make the flow ratio of suction and discharge port match the area ratio of two cavities of the differential cylinder well.As one of the three power sources of hydraulic system,gear pump plays an important role in the hydraulic system.Compared with plunger pump and vane pump,gear pump has many advantages,such as compact structure,strong anti pollution ability,good self-priming ability,stable and reliable operation,large speed range,low production cost and so on.Therefore,asymmetric gear pump is chosen as the research object to match the flow of differential cylinder.However,it is difficult to achieve accurate matching.Therefore,through the research of variable gear pump,the asymmetric gear pump is upgraded to the asymmetric variable gear pump to achieve small range change of flow and solve the above problems.In this paper,the problem of non variable gear pump is studied.Taking the single cavity trapped oil gear pump as the research object,a variable way is proposed to change the area of the trapped oil area by changing the position of variable slider,so as to change the effective volume of oil discharged from each cavity,so as to complete the small range variables of gear pump.In this paper,firstly,the structure and working principle of the variable gear pump are analyzed,and the internal structure of the gear pump is divided into regions and blocks,and the output flow pulsation,pressure pulsation,volume efficiency and other characteristics of the gear pump are analyzed through the theoretical calculation of the variable gear pump.The two-dimensional and three-dimensional models of the variable gear pump are established by using Auto CAD and Solid Works software,and the relevant structural parameters of the variable gear pump are measured.By using the method of centralized parameters,the hydraulic model of variable gear pump is built in simulation x,which is a multi-disciplinary modeling software.In the model,the modeling principle and characteristics of the variable gear pump hydraulic model are analyzed in detail,and the output results such as the output flow of the whole pump,the internal pressure of the tooth cavity and the variable characteristics of the single tooth cavity are analyzed under various working conditions of the variable gear pump.The conclusion that the variable effect of the variable gear pump is between 89% and 100% is obtained.The flow field simulation micro model of variable gear pump is established by the dynamic software pumplinx.The output characteristics of the whole pump,the internal pressure of the gear cavity and the vector of the oil flow velocity of the gear pump are analyzed to prove the variable effect of the gear pump and determine the displacement direction of the slider.The conclusion shows that the overall variable effect of the variable gear pump is between 90% and 100%,and the optimal displacement direction of the variable slider of the gear pump is "right"(oil inlet direction).Finally,the output of the asymmetric gear pump is used to simulate the regulating condition of the pump controlled differential cylinder.The results show that the asymmetric variable gear pump can solve the flow mismatch problem of pump controlled differential cylinder by fine tuning.In this paper,two kinds of simulation methods complement each other to prove the correctness of the variable mode and the accuracy of the simulation model.At the same time,two kinds of simulation software have their own emphases.The feasibility of variable mode is verified by different modeling methods and principles,which can provide a new way for the simulation research of hydraulic pump. |
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