Structural Assessment of Torque Converter at Operating Conditions: A Numerical Study

Abstract

A single stage torque converter consists of three elements — pump, stator and turbine. Pump and turbine are coupled by transmission fluid. Unlike a fluid coupling, however, a torque converter is able to multiply torque when there is a substantial difference between input and output rotational speed, thus providing the equivalent of a reduction gear. During its operation all these elements are subjected to centrifugal load, fluid pressure load and heat generated in transmission fluid. Overloading a converter can result in several failure modes, some of them potentially dangerous in nature: ballooning, blade deformation and defragmentation, overheating. In the current work a single stage torque converter, was modelled and analysed numerically for evaluating stress distribution and deformation. The engine operating speed at 2000 rpm was considered for analysis. For static analysis of torque converter components centrifugal load and fluid pressure load were considered. Analysis was carried out for six different speed ratios varying from zero to one. Variation of principal stresses (hoop stress and radial stress) and von-Mises stress has been discussed. Maximum stresses are found to be in pump at speed ratio of one and in turbine at speed ratio of zero. Maximum stresses are at shell core that is near to hub. Blade deformation in pump is maximum at coupling phase and in turbine it is maximum at stall condition. From these results it helps to predict the failure of torque converter components under different operating conditions.