Research On The Hydraulic Transformer

Compared with mechanical transmission and electric transmission, the hydraulic power transmission is in inferior, so many new kinds of components must be developed for improving hydraulic system efficiency. The Common Pressure Rail (CPR) is a new kind of hydraulic system and higher in efficiency, simpler in structure. But the CPR has not been widely applied because of having no higher efficiency components. The Hydraulic Transformer (HT) based on CPR is a new component, combining pump with motor, and adjusting load pressure. The HT is characteristics of higher in efficiency, simpler in structure and control of many actuators respectively, so the HT is increasing popular in engineering construction and mining machinery and has become main interests in hydraulic industry at home and abroad.Construction design, theoretical analysis, CFD, kinematics simulation and experimental research are used to study the HT. A new structure of the HT is proposed to expand the output pressure range. The pressure fields between the cylinder block and the valve plate and between the valve plate and the end housing have been set up, and the HT is designed and checked. The CFD is used to simulate the fluid fields of three kinds of distribution pairs. The simulation results show the real flow state well, therefore a new method is found out to optimize the HT. The simulations of instantaneous flow rate show that the high noise level is caused by the high flow ripple. The simulations of instantaneous driving torque show that the instantaneous driving torque is changed between the positive and the negative and fluctuated highly at the angle of the valve plate (θ≤15°), which result in the dead movement zone and the worse low-speed stability. Experimental results show the pressure regulation is realized using the HT and the ratio of p_A to p_B is from 0 to 1.2. The displacement of the HT depends on the angle of the valve plate, is not influenced by rotation speed and loads, further the displacement simulation results coincides with experimental results better. The output pressure depends on the angle of the valve plate and is influenced by loads. The research achievements provide the referenced basics in the future. The work is following as:In chapter 1, the history and current research status of the HT are introduced based on a lot of the publications and conference papers. The key technologies and applications are described. Also the research aim and significance are described.In chapter 2, the shortcomings of Innas HT are analyzed. A new structure of the HT is proposed to expand the output pressure scope. The pressure fields between the cylinder block and the valve plate and between the valve plate and the end housing have been set up, and the HT is designed...