Vehicle powertrain models using multibody dynamics.

摘要

In previous vehicle dynamics studies, the powertrain models employed have normally been one-dimensional torque/angular velocity models. These powertrain models calculate the torque correctly, but do not include the non-rotational degrees-of-freedom of the powertrain components and the interaction of these degrees-of-freedom with the vehicle chassis and suspension. This research focuses on the application of multibody dynamic simulation for powertrain modeling. A three-dimensional rigid body system can approximate all the characteristics of the powertrain for the purpose of dynamic analysis. This research extends the one-dimensional torque/angular velocity powertrain models to multibody dynamics models based on a recursive formulation.; The engine, torque converter, transmission, and differential are modeled as torque elements within this formulation. The engine torque element is connected to the engine body with revolute joints. The engine torque is transmitted through the torque converter, transmission, and differential component models to the drive axles. A point contact tire model is then used for the calculation of traction forces.; The powertrain component models are connected with the vehicle body and suspension component models by force elements, such as translational spring-damper-actuator elements (TSDA's), and kinematic constraints (revolute joint). The dynamic interaction between the powertrain and the vehicle models is obtained from these force elements and kinematic constraints. In order to highlight the methods, an example vehicle model composed of 10 bodies, utilizing two powertrain models, either a front-wheel-drive or rear-wheel-drive powertrain, is presented.; In this work, two new joint types are formulated for use in the powertrain model: a constant-velocity joint type and a tripod joint type. These joint types have not previously been used in multibody dynamics models. The constant-velocity joint type derived in this paper is exact. However, the tripod joint derivation has been simplified, assuming an ideal, constant-velocity tripod joint. Since the tripod joint-axis offset is quite small and does not vary much with suspension movement, the model is reasonably accurate while remaining computationally efficient.; In this research, more detailed dynamic behavior is shown for the rigid body powertrain system model than the one-dimensional torque/angular velocity powertrain model can. Thus, it is a valuable tool for performing powertrain design.