| Active vibration damping hydraulic suspension system has a broad application prospect in suspension system because of its advantages of improving ride comfort,handling stability and energy recovery.As its core component,gerotor pump should have the characteristics of wide speed(0-6000 r/min)and low pulsation.When the traditional gerotor pump is used in the wide speed operation of active vibration damping hydraulic suspension system,there are some outstanding problems,such as large pressure pulsation,low volumetric efficiency and wear of key pairs.Based on the dynamic operation condition of the gerotor pump in the active vibration damping hydraulic suspension system,the structure parameter design and kinematic characteristic analysis of the gerotor pump are carried out around the characteristics of wide speed and low pulsation,and the low pulsation design method of the gerotor pump is studied from the aspects of the rotor tooth profile of the gerotor pump,the characteristic parameters of the valve and the built-in buffer of the gerotor pump.Based on the wide-speed operation condition,the influence of the material and structure of the key pair of gerotor pump on its friction and wear characteristics is studied.The performance test of a prototype gerotor pump with wide speed and low pulsation is explained in order to effectively solve the gerotor pump wide-speed operating conditions of pressure pulsation,low volumetric efficiency,key pair wear problems.The design method of wide speed and low pulsation gerotor pump can provide theoretical basis for the design and manufacture of high performance active vibration damping hydraulic suspension system.The main work of this dissertation is as follows:(1)Dynamic characteristics analysis of gerotor pump in active damping system based on working conditions.The power unit transfer function of gerotor pump control cylinder of active vibration damping hydraulic suspension system is established,and the key factors affecting the hydraulic natural frequency and damping ratio of the system are analyzed.The system simulation model composed of DC servo motor,gerotor pump and hydraulic cylinder is built.Based on the suspension load of mediumsized car and typical road excitation,the closed-loop position control performance of active damping hydraulic system is studied,and the dynamic operating conditions of gerotor pump of active vibration damping hydraulic suspension system are quantitatively analyzed.The dynamic operating conditions characteristics of gerotor pump of active vibration damping hydraulic suspension system with wide speed range and obvious speed fluctuation are obtained.(2)Structural design and kinematic analysis of wide speed and low pulsation gerotor pump.For active vibration damping hydraulic suspension system,a compact gerotor pump with wide speed and low pulsation is designed.The influence of inner and outer rotor tooth profiles on the output pressure pulsation of gerotor pump is analyzed.Based on the forming mechanism of short-amplitude epicycloid,the mathematical model of tooth profile curve of inner and outer rotors is constructed,the meshing motion characteristics of inner and outer rotors of wide-speed gerotor pump are studied,and the variation law of relative slip velocity of meshing points of inner and outer rotors with rotational speed is revealed.(3)Research on low pulsation design of wide speed gerotor pump based on characteristic parameters of valve distribution.The mathematical model for calculating the displacement of gerotor pump in active vibration damping hydraulic suspension system is established by "sweeping area method",and its instantaneous flow rate and theoretical flow rate pulsation are accurately solved.The influence of distribution replica characteristic parameters on pressure pulsation and volumetric efficiency of wide-speed gerotor pump is studied.The results show that with the increase of rotating speed,the pressure pulsation of gerotor pump gradually increases.The toothed circular unloading groove of the valve pair has a significant influence on the pressure pulsation of the gerotor pump.When the rotating speed is 4000 r/min,the toothed circular unloading groove reduces the pressure pulsation by 7.57%.Under the condition of high rotational speed,the full tooth-shaped circular unloading groove has high volumetric efficiency.(4)Research on pressure pulsation suppression method of gerotor pump with builtin buffer.According to the characteristics of active vibration damping hydraulic suspension system,a diaphragm pulsation buffer built in gerotor pump of active damping system is proposed.The effect of diaphragm pulsation buffer on the output pressure pulsation of wide speed gerotor pump in active vibration damping hydraulic suspension system is quantitatively analyzed.The results show that the pulsation buffer has a remarkable effect on restraining the output pressure pulsation of gerotor pump under the conditions of variable speed and load.When the rotating speed is 1500 r/min,the pressure pulsation decreases by 44.61%.When the rotating speed is 5500 r/min,the pressure pulsation decreases by 38.66%.Under different load conditions,the pressure pulsation of gerotor pump decreases by about 40%.(5)Experimental study on friction and wear characteristics of key pairs of wide speed gerotor pump.Based on the surface texture technology,the influence of hemispherical surface texture on the bearing capacity of the gap oil film of the key pair of wide speed gerotor pump was studied by using new carbon fiber reinforced PEEK,9Cr18 and lead bronze materials.The experimental results show that the hemispherical surface texture has a significant effect on the friction coefficient and wear rate of PEEK and lead bronze.In addition,based on the theory of hydrodynamic bearing,the influence of the inclination of hydrodynamic guide rail on the characteristics of oil film flow field in the clearance of friction pairs is studied.It is found that the inclination angle of hydrodynamic guide rail is positively correlated with the axial average pressure of hydrodynamic guide rail,but the anti-wear advantage of hemispherical surface texture is weakened.(6)Prototype development and performance test of gerotor pump with wide speed and low pulsation.A prototype of a wide speed and low pulsation gerotor pump is developed,and the test system of the active vibration damping hydraulic suspension system is built.The pressure pulsation characteristics and flow characteristics of the wide speed gerotor pump are tested.The test results show that the volumetric efficiency of gerotor pump is 95.14% at 1500 r/min,and the pressure pulsation is reduced by 37.78%by pulsating buffer.With the increase of rotating speed,the volumetric efficiency decreases slightly,and the effect of pulsating buffer on suppressing pressure pulsation is weakened;Carbon fiber reinforced PEEK inner rotor and 9Cr18 outer rotor paired with lead bronze port plate can meet the needs of wide speed and low pulsation gerotor pump. |
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