Research And Analysis On The Characteristic Of Water Hydraulic Axial Piston Pump

Water hydraulic drive technology developing in recent years treats water as the working media to transmit power. Water hydraulic drive system has some advantages of oil hydraulic transmission such as large power, high efficiency and compact structure as well as the unique advantage of environment-protection. In water hydraulic transmission, what needs to be solved vitally is to develop its components. The low viscosity of water makes water hydraulic pumps, which are the vital components of the water hydraulic transmission system, have the big leakage and the short lifespan. Consequently, it is extremely vital developing the medium-high-pressure water hydraulic pump represented by the water hydraulic axial piston one and also further difficult.The work condition of friction pair is a key problem in designing the water hydraulic pump, which has important influence on its performance and lifespan. Because of low viscosity, the lubrication of water is poor, which makes the friction pair of the water hydraulic pump wear badly. The hydrostatic bearing technology is an efficient way to solve the wear if the material is fixed. In this thesis, after the principle, structure and design method of the port pair hydrostatic bearing of the current oil hydraulic pump are analyzed in combination with characteristics of water hydraulic axial piston pump, it is presented that the continuously supplying water hydrostatic bearing is more suitable for the water hydraulic axial end face porting piston pump; the dynamic mathematical models for the continuously supplying water porting pair are built and the optimized design method for it is presented based on the flow continuous equation between the damping groove and the pressure cavity, and the equation of motion.Based on the presented hydrostatic bearing model, the structure parameters of a water hydraulic pump porting pair are designed and calculated, the difference between the static model and the dynamicone is analyzed and it is pointed out that the effect of the damping decompression groove on it must be considered when the porting pair hydrostatic bearing is designed. The calculation indicates that the static model can meet the demand of designing the porting pair hydrostatic bearing structure. In addition, because the viscosity of water is low, the power loss of water film between the porting pair mainly depends on the leakage power loss while the friction power loss caused by the viscosity of water is small so that it can be ignored compared with the leakage one.According to simulation on the performance of the porting pair hydrostatic bearing, the power loss and water film thickness of it are discussed on the aspects of working pressure, water temperature and parameters of the hydrostatic bearing structure of pump. The calculation indicates that the porting pair hydrostatic bearing designed in the light of the rated work condition can meet with the demand of load fluctuation whereas the demand of the maximum water film on the processing of couple-pair surface has to be considered on the condition of maximum load for the water hydraulic pump with the large-scale variation in load. Because the variation of water temperature has minor effect on the water film thickness of porting pair, it can be neglected when calculating the water film thickness however the water temperature building-up will increase the power loss of porting pair. In the case of the certain processing condition, the hydrostatic bearing parameters must be confirmed in combination of the bearing structure comprehensively because the dimensions of the outer seal groove of the pressure balance cavity can affect the maximum water film thickness of porting pair.For the water hydraulic axial piston pump, its fluid noise mainly depends on the variation of flow rate and pressure during porting. In this thesis, simulation on the flow rate of pump and the pressure in the piston cavity is carried out applying the second-order models of flow rate and pressure. In terms of analysis of reducing the fluid noise of pis...