The Characteristic Analyses Of Bivariate Symmetric-type Structure Hydraulic Transformer

As the key component for the secondary regulation technology of the constant-pressure hydraulic rail system,hydraulic transformer is significant for flexible-control and energy-efficiency of the hydraulic system.It's brought into focus by researchers at home and abroad because of its constant power regulation characteristics,but there are still some disadvantages in this field.In the current technology,the maldistribution of the axial forces and the radial forces breaks the balance of the valve plate,which leads to the plate-burning phenomenon.And it also causes noise problems and reduce the service life of the hydraulic transformer.In thesis,a new type of bivariate symmetric-type hydraulic transformer is designed in order to solve these problems,and its mathematical model is established,and the correctness of the model is verified by CFD simulation.The system components of the bivariate symmetric-type hydraulic transformer are clearly introduced.According to the structure characteristics,such as the dip angle conditions of two side swash-plates,the symmetry and deflection angle circumstances of two side cylinders and the intersection angle conditions of the plates and the cylinders,the performance characteristics of the hydaulic transformer which includes its average flow,instantaneous flow,flow pulsation,average torque,instantaneous torque and transformer ratio are analyzed by modeling and simulation.The relationship between those characteristics and their impact factors are also concluded through the analyses.The impact factors of instantaneous flow consist of the intersection angles of the plates,the deflection angles of the cylinders and the dip angles of two side swash-plates.Specifically,the intersection angles of the plates impact its saltus,the deflection angles of the cylinders determine the occurring time of the saltus,and the dip angles of two side swash-plates influence the amplitude of the saltus.Without the consideration of the deflection angles of the cylinders,the flow pulsation rate is only related with the intersection angles of the plates and the number of the plungers;with the consideration of the deflection angles of the cylinders,the flow pulsation rate will also be impacted by the dip angles of the swash-plates.Theflow characteristics can be controlled by adjusting related variables.The transformer ratio is related with the intersection angles of the plates,the oil pressure of the T port and the friction torque.Specifically,the transformer ratio rises with the increase of the intersection angles of the plates while the ratio decreases with the increase of the friction torque.And there is a positive correlation between the ratio and the oil pressure of the T port when the ratio is bigger than 1 while the correlation changes into negative one when the ratio is smaller than 1.All these conclusions of the former simulations and analyses will be reasonable bases for further study.In the latter analysis of the inner flow field,it's concluded that the intersection angles of the plates only impact the amplitude of the flow and will never influence the variation trend while the dip angles of two side swash-plates can change the variation stage in a period of the instantaneous flow,on the basis of the numerical simulation test.The flow pulsation can be reduced by selecting reasonable angles motioned above.The results of the numerical simulation test conform completely with the mathematical model built in the study so that the model is proved correct.