Pressure performance improvement by dual-mode control in digital pump/motor

Due to the advantages of low cost, fast response and pollution resistance, digital hydraulic pump/motor can replace conventional variable hydraulic pump/motor in many application fields. However, digital hydraulic components produce large hydraulic impact at variable moments, which will shorten the service life of mechanical components. Through the simulation analysis of the variable process of digital pump/motor, it is found that the discontinuous flow caused by displacement step changes is the fundamental cause of hydraulic impact. The data analysis results of experimental tests are in good agreement with the simulation analysis results. In view of hydraulic secondary components, a variable control method based on dual-mode operating characteristics is proposed. The TOPSIS algorithm is used to give comprehensive evaluation of the displacement control results after this method. The results show that the control quality of digital pump/motor after adopting the control method has been effectively improved, with an average improvement of about 40%.