CAE DRIVELINE OPTIMIZATION

摘要

While the drivetrain’s main task is simply to transfer engine torque to the road, its design process is complicated by a number of issues like durability, packaging, NVH, driveability and costs. These issues often lead to conflicting requirements and thus the need for reasonable trade-offs. This paper deals with two case studies where trade-offs are unavoidable and offers solutions for finding the best compromise. One case study addresses the issue of driveline booming noise, taking into account NVH as well as driveability aspects. It also shows how the influence of NVH phenomena on interior noise can be estimated already in the early stages of the design process. The second case study deals with the static engagement clunk in vehicles with automatic transmission, where shifting the gears from “D to R” or “P to R” can lead to disturbing clunk noise and/or vibration. Optimizations are performed by tools such as Multi-Body Simulation (MBS) in combination with Vehicle Interior Noise Simulation VINS) and Computer Aided Testing (CAT). For the MBS approach, a full vehicle model is used consisting of vehicle body, chassis and driveline, I.e. powertrain, shafts, differential and wheels. The elastic suspensions of all major components, e.g. powertrain, differential, subframe, are considered as well. By means of sensitivity analysis, the influence of key parameters can be investigated, thus allowing the best design compromise to be found. For the investigation of booming noise, the influence of clutch characteristics and driveshaft stiffness are analyzed among others. Concerning static engagement clunk phenomena, the cause of the problem and possible solutions, such as clearance in the joints, are discussed in detail.