Analysis And Design Of Intelligent Automobile Fan Clutch

Magnetorheological (MR) fluids and Shape memory alloys (SMAs) are new type of intelligent materials. MR fluids are suspensions of micron-sized, magnetizable particles in a carrier fluid such as synthetic oil and silicone oil, which are regarded as the intelligent materials that respond to an applied magnetic field with a change in their rheological properties. With application of a magnetic field, its structure and properties changing rapidly within a few milliseconds, the apparent viscosity coefficient increased more than two orders of magnitude, will become similar to "solid" state. Once removing the magnetic field, MR fluids exhibit Newtonian-fluid-like behavior. SMAs have properties of shape memory effect and super-elastic. On role of external force, the residual deformation occurred in SMAs. Role in the temperature, the reverse deformation will happen, so that the material forms of restitution. In the process of restitution, great recovery force will occur if SMAs be bound, and can use its acting to make the intelligent drive. Based on the rheological behavior of MR fluids and the shape memory effect of SMAs, combined with the methods of mechanical design, the design and calculation model of intelligent fan clutch is build. The relationship of SMA Drive's driving force and output displacement with temperature are analyzed. The design formula of geometry is carried out, and its structure is designed. The main work in this dissertation is as follows:1) The composition of MR fluids, MR effect, and the main performance of MR fluids are presented. The research status of SMAs, shape memory effect,and the mechanical properties of SMAs are Introduced.2) Based on the Navier-Stokes equation and the Bingham model, combined with the working principle of intelligent fan clutch, MRF's flow in the fan clutch is analyzed,and the flow equation is derived. The relationship between torque and yield stress, the disc radius, working gap is carried out. The expression of the output speed is obtained.3) The principle and design method of SMA drive is analyzed. The Expression of SMA Drive's driving force and output displacement with temperature is established.4) According to the requirements of clutch's torque, parameters of the basic structure of the clutch is confirmed, and base on it, magnetic back track is designed, the working disc radius size is carried out. Meanwhile, the relation of torque, output speed and temperature are analyzed. 5) Utilize ANSYS software to carry out the imitation analysis of magnetic back track, and use the results to guidance the analysis of clutch performance.6) The experiment scheme of intelligent fan clutch is established.In this dissertation the innovations are summarized as follows:1) The equation of transmission torque is established. The expressions for the active thickness and volume of the MR fluids in clutch are proposed to provide the theoretical foundation for the design of the clutch.2) The SMA spring is designed. The Expression of SMA spring's driving force and output displacement with temperature is established. The torque control method on temperature is provided. A temperature-controlled intelligent automobile fan clutch design theory and methods is developed.