| Servo-motor-pump(SMP)is not only the power source of Electro-hydrostatic actuators(EHA),but also the vibration of EHA.The combination of the flow ripple of the servo-motor-pump and the system impedance will produce pressure ripple,causing system structural vibration and radiation noise,which greatly restricts the application of Electro-hydrostatic actuators in the field of ships.From the perspective of structural design,this topic focus on the suppression of flow ripple by the staggered phase parallel connection of double-gear-pump.Investigated the research status of EHA,it is concluded that EHA has less engineering applications in the field of ships.Compared the advantages and disadvantages of different types of hydraulic pumps of EHA,and concluded that internal gear pumps are the ideal power source for EHA.Summarized the research methods of suppress the flow ripple of hydraulic pumps,and decided to adopt the scheme of double-gear-pumps in staggered phase parallel to reduce the flow ripple of SMP.Established a double-pumps EHA model,and concluded that SMP is the main source of system vibration and noise.The scheme of using one motor to drive two hydraulic pumps coaxially,connecting two identical linear conjugate internal gear pumps through splines.Established the SMP model of parallel gear pumps,and proposed the adjustment of the spline staggered tooth installation strategy.The tooth profile equations of the internal and external gears are deduced by the tooth profile normal method,and Creo is used to model the structure of the gear pump.The swept area method is used to establish the flow ripple calculation method of a single linear conjugate internal gear pump and the parallel gear pumps,and the instantaneous flow curve of a single gear pump and the parallel gear pumps is drawn using Matlab.The analysis shows that the number of cycles of flow ripple during one revolution of the gear pump is equal to the number of teeth of the driving gear.The two gear pumps are installed staggered by 1/4 and 1/2 cycles respectively,and the flow ripple can be reduced by 38.73% and 75.56%.Pumplinx was used to analyze the influencing factors of the flow ripple of a single gear pump and the parallel gear pumps.Simulation results shows that the two gear pumps are staggered by 1/4 and 1/2 cycles respectively,the flow ripple can be reduced by 31.26% and65.89% respectively.As the speed increases,the instantaneous flow maximum value and flow ripple amplitude continue to increase,but the flow ripple pulsation rate continues to decrease.As the working pressure of the gear pump increases,the instantaneous flow maximum value of a single gear pump and a parallel gear pump continues to decrease,but the flow ripple value and flow ripple rate continue to increase.According to the《ISO 10767-2 Hydraulic fluid power-Determination of pressure ripple levels generated in systems and components》,test tooling for different working conditions were designed,and the pressure ripple test platform was built to conduct the test.The experiment shows: it is concluded that the two gear pumps are staggered by 1/4 and installed in 1/2 cycle,the pressure ripple is reduced by 34.50% and 67.96% respectively,and the flow ripple is reduced by 36.39% and 68.92% respectively.As the working pressure of the gear pump increases,the instantaneous flow maximum value of a single gear pump and a parallel gear pump continues to decrease,but the flow ripple value and flow ripple rate continue to increase. |
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