Research Of Pressure Pulsation Suppression Methods On Pump-Motor Closed Hydraulic System

After decades of development and research, pump—motor closed hydraulic drive technology can meet the demands in various conditions, and it has been used more and more widely. However, with the development of hydraulic technology, people pay more and more attention to the quality of the hydraulic system, the life of units and noise etc. Pressure pulsation, which has become a research focus on the current, is the main cause of reducing the life of units and bringing noise and vibration to the hydraulic system. In this paper, according to the analysis of the possible pressure pulsation mechanism while working in pump—motor closed-type hydraulic system, some effective methods, which are verified by simulation and test, to limit pressure pulsation are put forward. Main contents include:1. The characteristics, application and research status of the pump—motor closed hydraulic transmission are summarized. The reason, harness, and classification of the pressure pulsation of hydraulic system are analyzed. Combined with the present research situation of pressure pulsation and its restrain methods, the significance of research on the pressure pulsation of hydraulic system is clear.2. Based on the pump controlled motor closed hydraulic system, several main factors to cause the pressure pulsation are analyzed. According to the characteristics of the frequency of the pressure pulsation, a filter way is put forward and its feasibility is analyzed.3. The actual flow pulsation of piston pumps and piston motors is analyzed in theory. It is concluded that the actual output flow pulsation of piston unit is mainly affected by plate structure and the leakage. The flow pulsation of piston pumps is simulated. The simulation results show that the actual value of flow pulsation is much more than the theoretical value, and the actual value is twice of the theoretical value in frequency. The influence on the system pressure pulsation by the actual flow pulsation of the piston pumps and piston motors is studied by simulation. And the simulation results verify the feasibility by using the piston pumps and piston motors to realize mutual filtering.4. The simulation model of variable displacement pump—motor with fixed displacement is established in SIMULINK. The changes of system pressure with the changing of load are proved by the simulation. The results show that the output flow of the pump changes linearly with the change of the control current, the pressure stability of low pressure circuit has certain influence on the pressure of high pressure circuit. The load change can cause the pressure pulsation of the system and changing some parameters of the system appropriately or using the accumulator can reduce the pressure pulsation.5. Pump—motor closed hydraulic experimental platform is built. The experiment proves the feasibility of mutual filtering through the actual flow pulsation. The influence on the pressure of high pressure circuit by the pressure stability of low pressure circuit is proved by an engineering example. The results show that ensuring the pressure stability of low pressure circuit can reduce the pressure pulsation on the high pressure circuit effectively.