Abstract

The presented paper deals with the multidisciplinary analysis of pump shaft dynamical behavior in a variable displacement oil pump for truck applications. Goal of the paper is the calculation of transmitted torque on pump shaft in order to prevent unfitting of pressfitted parts under crankshaft torsional vibrations and specific pressure time-history calculated by CFD analysis. A simulation model was developed using a multi-body code. Main components of the pump that influence the dynamics of system have been modeled including crankshaft gear. Crankshaft torsional vibrations have been experimentally measured by the customer and have been implemented as input data in the model.
The other important input data are CFD-simulated pressure loads inside the pump. The pressure loads in the pump have been extracted from a CFD simulation with Pumplinx simulating pump assembly in high speed engine test conditions with a low aeration level. From CFD results, pressure values inside pump chambers have been available for a complete pump revolution using a monitor point placed inside pumping chambers. The obtained pressure profile over 360 degree rotation of pump rotor has been then used to obtain resulting force on each vane (separating two pump chambers). This load has been inserted in multi-body model.
Typically in transient analysis the response of system is highly influenced by contact stiffness/dumping. In this analysis, contact parameters in gear transmission has been tuned according to a dedicated static structural simulation (FEA). At least, experimental campaign was conducted to measure the unfitting torque and simulation results has been compared to experimental data. Two different loading conditions have been considered, corresponding on two different duration tests.