Finite Element Analysis of Crankshaft Deformation after Shrinkage Fit of Rotor Wan Kok How / Chong San Haw Panasonic Refrigeration Devices Singapore Pte. Ltd. Abstract As a Reciprocating Compressor manufacturer, improving the reliability of our products has always been one of our goals. Our R&D Centre constantly studies ways in reducing the market reject rate of household refrigerator compressors. This project aims to eliminate the chances of the compressors running into failure by improving the existing design and considering the effect of the Rotor shrinkage when fitted to Crankshaft. In this finite element analysis, the 3D model is built using Pro/Engineer WildFire3.0 3D CAD. ANSYS WORKBENCH is then activated to import the 3D model and simulate the deformation of Crankshaft Main Journal after shrink-fitting the Rotor. Finally actual measurement is conducted to compare and verify the FEA results. The experimental results agreed well with the pattern of the Deformation vs. Interference obtained using CAE simulation. Introduction A compressor is an essential component in a refrigeration system that uses the vapor compression system. The function of the compressor is to compress the refrigerant from low pressure to high pressure. Basic types of compressors being used in refrigerator are reciprocating compressors and rotary compressors; our company in Singapore only produces reciprocating compressors. The cut away view of a conventional reciprocating compressor used for household refrigerator is shown in Figure 1 . The crankshaft rotates with a load and hence friction will occur at the bearing surface. Therefore the crankshaft to bearing surface should be reduced to minimize the friction loss. However reducing the frictional area increases the rate of wearing off of the frictional face. The frictional area is indicated by red arrow in Figure 1 . Our product is based on calculating the expected wear magnitude after 10-years of service based on the Sommerfeld number and past data to confirm the necessary reliability. The mechanisms of a reciprocating compressor mainly consist of Piston, Con-rod & Crankshaft. The Crankshaft is rotating at about 3000rpm in the bearings and it consists of the main shaft portion and the eccentric shaft portion. The motor driving torque is transferred to the eccentric shaft portion from the main shaft portion, where work is done to rotate the eccentric shaft portion. During compression, the forces acting on Piston and Crankshaft are shown in Figure 2 . This design is widely used in smaller capacity compressors due to its cost effectiveness. The mechanism should be able to withstand up to a certain degree of compression force from the piston during operation. Too much force may result in deformation of mechanical parts and this will create undesirable wear and tear. In worse cases, the compressor may cease to operate.
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Finite Element Analysis of Crankshaft Deformation after Shrinkage Fit of Rotor Wan Kok How / Chong San Haw