Thermodynamic Research On The Oil-water Separation Axial Piston Pump With Port Valves

Water hydraulics use water as the hydraulic medium, which have the advantages of environmental protection, economy and security. However, due to the low viscosity of water, worse lubricating condition will occur in hydraulic components. In the oil-water separation piston pump, mineral oil serves as lubricant and water as hydraulic medium, which combines the advantages of water hydraulics and oil hydraulics very well. As mineral oil is enclosed in chamber, there is a risk of too high oil temperature. So, how to predict the change of oil temperature is essential. Moreover, the research will contribute to the design and optimization of piston water pump.In this paper, with the aid of kinetic theory and knowledge of heat transfer, the mechanism of heat production and transfer are analyzed, and the map of heat flow is built. It is difficult to deal with irregular components by using traditional theories. By means of finite element analysis tools, the viscous friction in oil chamber and the heat conduction of cylinder are studied, and relevant results are obtained. Besides, the detail thermodynamic model of pump is established. And based on the mathematic model, the influence of pressure, speed and the friction coefficient effecting on oil temperature are discussed, the distribution of heat production and dissipation is also analyzed. At last, several experiments are conducted on an oil-water separation axial piston pump to test and verify the thermodynamic model, and the change of oil temperature in different operating conditions are measured.The main conclusions are: piston/ cylinder pair is the main source of heat production, and heat conduction of cylinder contributes the largest part of heat dissipation; piston/ glyd ring is the major part of heat production in piston pairs when the port pressure is low, and piston/ cylinder is the main form of heat production in piston pairs when the port pressure is high; the built mathematic model is proved to be effective in predicting the change of oil temperature.