| In recent years,the development of the water hydraulic drive technology is far from the oil hydraulic drive technology because of the physical and chemical characteristics of water,and it have a lot of problem in the material,structure and design,so that there is less mature hydraulic pump on the market,also it's cost much.At present,the design concept of the water hydraulic pump is similar to the oil hydraulic piston variable pump,which use the plunger to reciprocate in the cylinder body in the angle of the inclined plate.It has little control method,the structure of the pump is more complex,the flow fluctuation is larger and the dependability is lower than the oil hydraulic pump.Therefore,this paper designed a new water hydraulics variable piston pump which is integrated with the oil hydraulic components,the simple water hydraulic components and the mechanical mechanism.The driving and control part of the pump adopts mature,reliable and high performance oil hydraulic components,the water transmission and energy output part of the pump adopts some simple hydraulic components,such as hydraulic cylinder,check valve and accumulator etc.Compared with the traditional hydraulic pump,the structure is simple and the control performance is not reduced.This paper mainly completes the following research:(1)According to the requirements of the special parameters of the new water hydraulic pump,put forward two design schemes,analysis the force and the movement rules respectively,and compare two schemes from the aspects of structural variability,structural compactness,processing difficulty and economy.Finally select the optimal solution.(2)Based on the scheme of water hydraulic pump,the size of several key components is calculated,the basic size of water hydraulic cylinder is determined.According to the special environment of water hydraulic cylinder,select material and seal element.Based on the size of water hydraulic cylinder,design the valve block.Finally the 3D model of the water hydraulic pump is built.(3)Based on the water hydraulic pump structure,the static and dynamic analysis was carried out by using ANSYS Workbench.The static analysis results shows that the maximum stress is 114.79MPa,which is lower than the allowable stress of the material 154.1 MPa and the maximum deformation is 0.078mm,which is less than the maximum allowable deflection.Hydraulic cylinder can meet the requirements of mechanical properties,but there is an optimization space.The modal analysis results show that the dynamic characteristics are good,and it will not resonate with the external excitation source.The optimal design of hydraulic cylinder is carried out with the aim of maximum stress,maximum deformation and mass.The results show that the maximum stress of the model is reduced by 17.19MPa,which accounts for 14.98%of the former model,and is less than allowable stress of the material.The maximum deformation is reduced by 0.013mm,accounting for 16.46%of the former model,and the total mass of the model is reduced by 1.46kg,which is about 8.07%of the total mass.Therefore,the static performance of the optimized model meets the requirements.Finally the modal analysis is carried out.The results show that the structure has good dynamic characteristics.(4)Based on the optimized model of the water hydraulic pump,the output characteristics of the flow are analyzed and calculated.In order to solve the problem of flow fluctuation,the accumulator is set at the outlet of the water hydraulic pump to absorb the flow fluctuation.Using AMESim software to bulid the mathematical modeling of the water hydraulic pump system,and discuss the influencing factors of the accumulator to absorb fluctuation.Results show that the accumulator can absorb fluctuation effectively,the larger the pressure and volume of accumulator,the smaller the flow fluctuation. |
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