Research On The Oil Flow,Heat Transfer And Torque Property Of A Engine Silicone-oil Fan Clutch

As one of the representative products of hydroviscous drive technology,silicone-oil fan clutch uses viscous shearing force of silicone oil to transfer torque and plays an important role in different engine cooling systems.Compared with the traditional direct-connected cooling fan,silicon-oil fan clutch can automatically regulate fan speed according to the air temperature of engine chamber,which can make the engine work steadily.Therefore,the silicone-oil fan clutch can not only reduce the fuel consumption of the engine,but also reduce the fan noise when the engine starts,and ultimately achieve the goal of energy saving and emission reduction.The internal fluid of the shearing chamber is the basis of the torque transmission,of which the silicon-oil fan clutch can realize.So the research on the oil flow,heat transfer and torque property of an engine silicone-oil fan clutch has great meaning to the development of silicone-oil fan clutch products.The shearing chamber of double oil grooves bimetal silicone-oil fan clutch has been studied,combining the method of numerical simulation and theoretical study,the flow,heat transfer and torque performance of the oil film in the shearing chamber were analyzed,and the torque transfer characteristics of the oil film in the shearing chamber were studied with the affect factor including oil supply,input speed and oil film thickness.The main contents are as follows:In chapter 1,the hydroviscous drive technology,the working medium used by silicone-oil fan clutch and the structure characteristics and working principle of silicone-oil fan clutch are introduced,a review of silicone-oil fan clutch from the aspects of theoretical analysis,influencing factors and control system is summarized,the significance of silicone-oil fan clutch research is described and the main research contents of this paper are put forward.In chapter 2,the oil flow in the shearing chamber of the silicone-oil fan clutch is studied.The calculation model of oil film in the shearing chamber is established and the characteristics of oil flow is solved by means of computational fluid dynamics(CFD).The cloud diagram of velocity,vector diagram and pressure distribution of fluid in shearing chamber are obtained by simulation,focusing on the intersection area between torus and cylinder,the average speed in this region is obtained by setting different speed and oil supply,which makes a foundation for the calculation of transfer torque in the intersection area.In chapter 3,the heat transfer phenomenon of silicon-oil fan clutch is studied.A heat transfer model of silicone-oil fan clutch is established,the calculation program of clutch surface and silicone-oil temperature are developed.Based on the calculation model in chapter 2,the cloud diagram of temperature distribution and temperature rise of the oil film in the shearing chamber under adiabatic and isothermal conditions are obtained with considering of the effects of viscosity-temperature characteristics.In chapter 4,the mechanical properties of silicone-oil fan clutch are studied.A mathematical model of centrifugal force in oil storage chamber,a simplified mathematical model of shearing chamber and a mathematical model of oil return pressure of the oil return mechanism of silicone-oil fan clutch are established,meanwhile,the approximate solutions to these models are obtained.The influence of different factors on the rate of flow and the output torque is analyzed,the influence of the intersection area on the output torque is calculated,and the influence factors of oil return sensitivity are analyzed.