Multi-Field Coupling Simulation And Oil Way Dynamic Optimization Of Wet Multi-Plate Friction Clutch

Wet multi-plate friction clutches are widely used in marine transmission system, it is the important part to implement cut off and transfer power between prime mover and transmission system. With the development of clutch, the power and speed are higher, and the weight is lighter, the heating phenomenon of clutch is more serious. The research shows that the drastic oil-shear heating is a main reason to result in the excessive heating of clutch. Therefore, it necessary to conduct the multi-field coupling simulation and oil way dynamic optimization of wet multi-plate friction clutch, and it has important theory significance and great engineering value to solve the problem of excessive heating and improve the efficiency.Focusing on wet multi-plate friction clutch at the state of disengaged, the flow field dynamic simulation, thermal-fluid-solid coupling simulation and oil way dynamic optimization are conducted. The main work in this thesis can be summarized as follows:(1) According to the structure of clutch and the force condition of clutch plates, the clutch plates transient equations of motion are derived. The parameterized finite element model of oil flow field is built in ANSYS/CFX, combining with the transient equations of motion, the flow field dynamic simulation of the clutch is conducted by dynamic mesh technology. Then the separating process dynamic characteristics of flow field and the oil layer thickness distributing are explored.(2) Based on the Newton's law of inner friction and oil-shear mechanism, the towing torque mathematical model of clutch which contain the friction plates with radial and circumferential grooves is built, and calculates the analytical solutions of towing torque. Then the parametric discrete model of oil film is established, the numerical solutions of towing torque are achieved by using the finite element method, and make a comparison with the analytical solutions. In addition, the research on the influence law of towing torque affected by the groove forms, the speeds of drive shaft and oil temperatures is conducted.(3) Taking the oil way model at stable state gained from the fluid simulation as the research object, the thermal-fluid coupling dynamic simulation of flow field is conducted, and the distribution of oil pressure and oil temperature are analyzed. Focusing on clutch plates and oil layer between the clutch plates, the multi-field coupling analysis model is built on the basis of the thermal-fluid coupling simulation results, and the flow field, the oil temperature field, the displacement field and the stress field of clutch are achieved. In addition, the influencing laws of oil pressure, oil temperature, equivalent stress and synthetic displacement of clutch plates by oil film thickness and rotational speed are explored.(4) Taking the diameter of oil holes as the design variables, the oil pressure range of the clutch as constraint conditions, the RMS value of variance of each oil layer thickness as the objective function, the parametric dynamic optimization of oil way is created. To get the optimal structure of oil way, the dynamic optimization is conducted by the corresponding surface method. And then to get the optimization effect, the results before and after the optimization are analyzed. The result shows that the optimization effect is great.